Wong, T., P. W. Stackhouse Jr., P. Sawaengphokhai, J. Garg, and N. G. LoebWong, T., P. W. Stackhouse Jr., P. Sawaengphokhai, J. Garg, and N. G. Loeb, 2022: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2021”]. Bull. Amer. Meteor. Soc., 103(S75-S77). doi: 10.1175/BAMS-D-22-0092.1.
Wong, T.; Stackhouse Jr, PW; Sawaengphokhai, P.; Garg, J.; Loeb, N. G.Wong, T., P. Stackhouse Jr, P. Sawaengphokhai, J. Garg, N. G. Loeb, 2022: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2021”]. Bull. Amer. Meteor. Soc., 103(8), S75-S77. doi: https://doi.org/10.1175/2022BAMSStateoftheClimate.1.
Stackhouse, P. W., T. Wong, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, D. P. Kratz, and N. G. LoebStackhouse, P. W., T. Wong, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, D. P. Kratz, and N. G. Loeb, 2021: Earth Radiation Budget at Top-of-atmosphere [in "State of the Climate in 2020"]. Bull. Amer. Meteor. Soc., 102(8). doi: 10.1175/2021BAMSStateoftheClimate.1.
Wong, T., P. W. Stackhouse, Jr., D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. LoebWong, T., P. W. Stackhouse, Jr., D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. Loeb, 2020: Earth Radiation Budget at Top-of-atmosphere [in "State of the Climate in 2019"]. Bull. Amer. Meteor. Soc., 101(8). doi: 10.1175/2020BAMSStateoftheClimate.1.
Wong, T.; Stackhouse, P. W.; Kratz, D. P.; Sawaengphokhai, Parnchai; Wilber, A. C.; Gupta, S. K.; Loeb, N. GWong, T., P. W. Stackhouse, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2020: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2019”].. Bull. Amer. Meteor. Soc, 101(8), S68-69. doi: 10.1175/BAMS-D-20-0104.1.
Shrestha, A. K.; Kato, S.; Wong, T.; Stackhouse, P.; Loughman, R. P.Shrestha, A. K., S. Kato, T. Wong, P. Stackhouse, R. P. Loughman, 2019: New Temporal and Spectral Unfiltering Technique for ERBE/ERBS WFOV Nonscanner Instrument Observations. IEEE Transactions on Geoscience and Remote Sensing, 1-12. doi: 10.1109/TGRS.2019.2891748. Earth Radiation Budget Experiment (ERBE) Wide-Field-of-View (WFOV) nonscanner instrument onboard Earth Radiation Budget Satellite (ERBS) provided critical 15-year outgoing broadband irradiances at the top of atmosphere (TOA) from 1985 to 1999 for studying Earth's climate. However, earlier studies show that the uncertainty in this radiation data set (Ed3) is significantly higher after the Mt. Pinatubo eruption in 1991 and satellite battery issue in 1993. Furthermore, Lee et al. showed that the transmission of ERBS WFOV shortwave dome degraded due to exposure to direct sunlight. To account for this degradation, a simple time-dependent but spectral-independent correction model was implemented in the past. This simple spectral-independent model did not completely remove the shortwave sensor artifact as seen in the temporal growth of the tropical mean day-minus-night longwave irradiance. A new temporal-spectral-dependent correction model of shortwave dome transmissivity loss similar to that used in the Clouds and the Earth's Radiant Energy System (CERES) project is developed and applied to the 15-year ERBS WFOV data. This model is constrained by the solar transmission obtained from ERBS WFOV shortwave nonscanner instrument observations of the Sun during biweekly in-flight solar calibration events. This new model is able to reduce the reported tropical day-minus-night longwave irradiance trend by ≈34%. In addition, the slope of this new trend is observed to be consistent over different regions. The remaining trend is accounted using a postprocess Ed3Rev1 correction. Furthermore, the time series analysis of these data over the Libya-4 desert site showed that the shortwave data are stable to within 0.7%. Earth; Instruments; Meteorology; Satellite broadcasting; Radiometry; Data models; Calibration; Data conversion; earth; energy measurements.
Stackhouse, P. W.; Wong, T.; Kratz, D. P.; Sawaengphokhai, Parnchai; Wilber, A. C.; Gupta, S. K.; Loeb, N. GStackhouse, P. W., T. Wong, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2019: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2018”].. Bull. Amer. Meteor. Soc, 100(9), S46-48. doi: 10.1175/2019BAMSStateoftheClimate.1.
Stackhouse, P. W.; Wong, T.; Kratz, D. P.; Sawaengphokhai, Parnchai; Wilber, A. C.; Gupta, S. K.; Loeb, N. GStackhouse, P. W., T. Wong, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2019: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2018”].. Bull. Amer. Meteor. Soc, 100(9), S46-48. doi: 10.1175/2019BAMSStateoftheClimate.1.
Xu, Kuan-Man; Hu, Yongxiang; Wong, TakmengXu, K., Y. Hu, T. Wong, 2019: Convective Aggregation and Indices Examined from CERES Cloud Object Data. Journal of Geophysical Research: Atmospheres, 124(24), 13604-13624. doi: 10.1029/2019JD030816. Convective aggregation is a self-aggregation phenomenon appearing in idealized radiative-convective equilibrium simulations under constant, uniform sea surface temperature (SST). To gain an understanding of observed convective aggregation or organization, three metrics, i.e., simple convective aggregation index (SCAI), modified SCAI (MCAI), and convective organization potential (COP), are evaluated with cloud object data from CERES. MCAI is related to object sizes through a modified inter-object distance (IOD). It is found that large-size object groups are less aggregated according to SCAI but more organized according to COP, compared to small-size object groups. The opposite sensitivities to object-group size can be explained by the dominant roles of the IOD in SCAI and the sum of object radii in COP as object-group sizes increase. However, large-size object groups are slightly more aggregated than small-size ones according to MCAI. Both SCAI and MCAI increase with the number of cloud objects (N) in an object group but COP has a weak dependency on N. Further sorting by object-group total area shows that sensitivity of MCAI to object-group area agrees with that of SCAI for small-area ranges but with that of COP for large-area ranges, which is related to the weak sensitivity of the modified IOD to object-group area, as compared to that of the original IOD. Finally, the three metrics show the similar contrasts between continental and oceanic convection and the same weak sensitivity to SST. The latter suggests that self-aggregation is weaker at higher SSTs than at lower SSTs, in contrast to the findings of many simulations. Cloud object; Convective aggregation; Convective aggregation index
Wong, T.; Kratz, D. P.; Stackhouse, P. W.; Sawaengphokhai, Parnchai; Wilber, A. C.; Gupta, S. K.; Loeb, N. GWong, T., D. P. Kratz, P. W. Stackhouse, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2018: Earth Radiation Budget at Top-Of-Atmosphere [in “State of the Climate in 2017”].. Bull. Amer. Meteor. Soc, 99(8), S45-46. doi: 10.1175/2018BAMSStateoftheClimate.1.
Wong, T.; Smith, G. L.; Kato, S.; Loeb, N. G.; Kopp, G.; Shrestha, A. K.Wong, T., G. L. Smith, S. Kato, N. G. Loeb, G. Kopp, A. K. Shrestha, 2018: On the Lessons Learned From the Operations of the ERBE Nonscanner Instrument in Space and the Production of the Nonscanner TOA Radiation Budget Data Set. IEEE Transactions on Geoscience and Remote Sensing, 56(10), 5936-5947. doi: 10.1109/TGRS.2018.2828783. Monitoring the flow of radiative energy at top of atmosphere (TOA) is essential for understanding Earth's climate and how it is changing with time. The determination of TOA global net radiation budget using broadband nonscanner instruments has received renewed interest recently due to advances in both instrument technology and the availability of small satellite platforms. The use of such instruments for monitoring Earth's radiation budget was attempted in the past from satellite missions such as the Nimbus-7 and the Earth Radiation Budget Experiment (ERBE). This paper discusses the important lessons learned from the operation of the ERBE nonscanner instrument and the production of the ERBE nonscanner TOA radiation budget data set that have direct relevance to current nonscanner instrument efforts. Earth; Extraterrestrial measurements; atmospheric radiation; atmospheric techniques; Instruments; Meteorology; atmospheric measuring apparatus; Atmospheric measurements; uncertainty; Sea measurements; Satellite broadcasting; Data conversion; broadband nonscanner instruments; current nonscanner instrument efforts; Earth Radiation Budget Experiment; Earth's climate; energy measurement; ERBE nonscanner instrument; ERBE nonscanner TOA radiation budget data; important lessons; instrument technology; monitoring Earth's radiation budget; Nimbus-7; nonscanner TOA Radiation Budget data set; radiative energy; small satellite platforms; TOA global net radiation budget
Kratz, D. P.; Stackhouse, P.W.; Wong, T; Sawaengphokhai, P.; Wilber, A. C.; Gupta, S. K.; Loeb, N. G.Kratz, D. P., P. Stackhouse, T. Wong, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2017: Earth radiation Budget at Top-of-Atmosphere [in “State of the Climate in 2016"]. Bull. Amer. Meteor. Soc., 97(8), S41-S42. doi: 10.1175/2017BAMSStateoftheClimate.1.
Shrestha, A. K., S. Kato, T. Wong, P. W. Stackhouse, F. Rose, W. F. Miller, K. Bush, D. A. Rutan, P. Minnis, D. DoellingShrestha, A. K., S. Kato, T. Wong, P. W. Stackhouse, F. Rose, W. F. Miller, K. Bush, D. A. Rutan, P. Minnis, D. Doelling, 2017: Spectral Unfiltering of ERBE WFOV Nonscanner Shortwave Observations and Revisiting its Radiation Dataset from 1985 to 1998. 2016 International Radiation Symposium – Radiation Processes in the Atmosphere and Ocean, 1810(90008). doi: 10.1063/1.4975548.
Thampi, Bijoy; Wong, Takmeng; Lukashin, Constantin; Loeb, Norman GThampi, B., T. Wong, C. Lukashin, N. G. Loeb, 2017: Determination of CERES TOA fluxes using Machine learning algorithms. Part I: Classification and retrieval of CERES cloudy and clear scenes. J. Atmos. Oceanic Technol., 34(10), 2329–2345. doi: 10.1175/JTECH-D-16-0183.1. Continuous monitoring of the Earth radiation budget (ERB) is critical to our understanding of the Earth’s climate and its variability with time. The Clouds and the Earth’s Radiant Energy System (CERES) instrument is able to provide a long record of ERB for such scientific studies. This manuscript, which is first of a two-part paper, describes the new CERES algorithm for improving the clear/cloudy scene classification without the use of coincident cloud imager data. This new CERES algorithm is based on a subset of modern artificial intelligence (AI) paradigm called Machine Learning (ML) algorithms. This paper describes development and application of the ML algorithm known as Random Forests (RF) which is used to classify CERES broadband footprint measurements into clear and cloudy scenes. Results from the RF analysis carried using the CERES Single Scanner Footprint (SSF) data for the months of January and July are presented in the manuscript. The daytime RF misclassification rate (MCR) shows relatively large values (>30%) for snow, sea ice and bright desert surface types while lower values of (
Xu, Kuan-Man; Wong, Takmeng; Dong, Shengtao; Chen, Feng; Kato, Seiji; Taylor, Patrick C.Xu, K., T. Wong, S. Dong, F. Chen, S. Kato, P. C. Taylor, 2017: Cloud object analysis of CERES Aqua observations of tropical and subtropical cloud regimes: Evolution of cloud object size distributions during the Madden–Julian Oscillation. Journal of Quantitative Spectroscopy and Radiative Transfer, 188, 148–158. doi: 10.1016/j.jqsrt.2016.06.008. In this study, we analyze cloud object data from the Aqua satellite between July 2006 and June 2010 that are matched with the real-time multivariate Madden–Julian Oscillation (MJO) index to examine the impact of MJO evolution on the evolutions of the size distributions of cloud object types. These types include deep convective (DC), cirrostratus, shallow cumulus, stratocumulus and overcast-stratus. A cloud object is a contiguous region of the earth with a single dominant cloud-system type. It is found that the cloud object size distributions of some phases depart greatly from the 8-phase combined distribution at large cloud-object diameters. The large-size group of cloud objects contributes to most of the temporal variations during the MJO evolution. For deep convective and cirrostratus cloud objects, there is a monotonic increase in both the number and footprint of large objects from the depressed to mature phases, which is attributed to the development and maturing of deep convection and anvils. The largest increase in the mean diameter during the mature phases that lasts to the early dissipating phase is related to growth of anvil clouds and is accompanied by moderate decreases in small-size objects. For shallow cumulus, the large objects decrease in number at the mature phases, but increase in number for both sizes before the mature phase. The opposite is true for the large overcast-stratus objects. The temporal evolution of large stratocumulus objects is similar to that of deep convective and cirrostratus object types except for peaking slightly earlier. CERES; Aqua observations; cloud regimes; Cloud size distribution; Madden-Julian Oscillation
Kato, Seiji; Xu, Kuan-Man; Wong, Takmeng; Loeb, Norman G.; Rose, Fred G.; Trenberth, Kevin E.; Thorsen, Tyler J.Kato, S., K. Xu, T. Wong, N. G. Loeb, F. G. Rose, K. E. Trenberth, T. J. Thorsen, 2016: Investigation of the residual in column integrated atmospheric energy balance using cloud objects. J. Climate, 29(20), 7435–7452. doi: 10.1175/JCLI-D-15-0782.1. Observationally-based atmospheric energy balance is analyzed using Clouds and the Earth’s Radiant Energy System (CERES)-derived TOA and surface irradiance, Global Precipitation Climatology Project (GPCP)-derived precipitation, dry static and kinetic energy tendency and divergence estimated from ERA-Interim, and surface sensible heat flux from SeaFlux. The residual tends to be negative over tropics and positive over mid-latitudes. A negative residual implies that precipitation rate is too small, divergence is too large, or radiative cooling is too large. The residual of atmospheric energy is spatially and temporally correlated with cloud objects to identify cloud types associated with the residual. Spatially, shallow cumulus, cirrostratus, and deep convective cloud object occurrence are positively correlated with the absolute value of the residual. The temporal correlation coefficient between the number of deep convective cloud objects and individual energy components, net atmospheric irradiance, precipitation rate, and the sum of dry static and kinetic energy divergence and their tendency over western Pacific are, respectively, 0.84, 0.95, and 0.93. However, when all energy components are added, the atmospheric energy residual over tropical Pacific is temporally correlated well with the number of shallow cumulus cloud objects over tropical Pacific. Because shallow cumulus alters not enough atmospheric energy compared to the residual, these suggest 1) if retrieval errors associated with deep convective clouds are causing the column integrated atmospheric energy residual, the errors vary among individual deep convective clouds, and 2) it is possible that the residual is associated with processes in which shallow cumulus clouds affect deep convective clouds and hence atmospheric energy budget over tropical western Pacific.
Loeb, N. G.; Su, W.; Doelling, D. R.; Wong, T.; Minnis, P.; Thomas, S.; Miller, W. F.Loeb, N. G., W. Su, D. R. Doelling, T. Wong, P. Minnis, S. Thomas, W. F. Miller, 2016: Earth's Top-of-Atmosphere Radiation Budget. Reference Module in Earth Systems and Environmental Sciences. The top-of-atmosphere (TOA) Earth radiation budget (ERB) is a key property of the climate system that describes the balance between how much solar energy the Earth absorbs and how much terrestrial thermal infrared radiation it emits. This article provides an overview of the instruments and algorithms used to observe the TOA ERB by the Clouds and the Earth's Radiant Energy System (CERES) project. We summarize the properties of the CERES instruments, their calibration, combined use of CERES and imager measurements for improved cloud-radiation properties, and the approaches used for time interpolation and space averaging of TOA radiative fluxes. calibration; clouds; longwave; shortwave; broadband; CERES; climate; radiation budget; top-of-atmosphere; flux; Time interpolation
Smith, G. L.; Wong, T.Smith, G. L., T. Wong, 2016: Time-Sampling Errors of Earth Radiation From Satellites: Theory for Monthly Mean Albedo. IEEE Transactions on Geoscience and Remote Sensing, 54(6), 3107-3115. doi: 10.1109/TGRS.2015.2503982. The Earth Radiation Budget Experiment wide-field-of-view (WFOV) radiometers aboard the Earth Radiation Budget Satellite (ERBS) provided a 15-year record of high-quality measurements for research into the radiant energy balance of the Earth. Monthly mean maps of RSR and outgoing longwave radiation (OLR) are primary data products from these measurements. The ERBS orbit had an inclination of 57° so as to precess through all local times every 72 days. Because of limited temporal sampling, some regions were not measured sufficiently often by the WFOV radiometers to produce accurate radiation flux values for these maps. The temporal sampling of any one region is very irregular; therefore, it is necessary to consider each region in detail for each month. An analysis of the errors, which result from computing the average value of the albedo of a region over a day or month based on limited sampling, is presented. It is necessary to take into account synoptic variations and their time correlations and differences of the regions' diurnal cycle from that assumed by the time-averaging algorithms. An expression is derived for the variance of the error of the computed daily and monthly mean albedo. Temporal correlation and variability of the albedo field are specified a priori. This analysis has been used for quality assurance to evaluate the temporal sampling errors of monthly mean RSR maps computed from the measurements by the WFOV radiometers aboard the ERBS and to delete those values for which the error variance is excessive. Earth; earth radiation budget; Extraterrestrial measurements; atmospheric techniques; radiometers; Time measurement; Sea measurements; diurnal cycle; Orbits; outgoing longwave radiation; correlation; Error analysis; time-sampling errors; Earth radiation budget experiment wide-field-of-view radiometers; ERBS orbit; high-quality measurements; limited temporal sampling; radiation flux; RSR maps; sampling errors; time-averaging algorithms; WFOV radiometers
Stackhouse, P., D. P. Kratz, T. Wong, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. LoebStackhouse, P., D. P. Kratz, T. Wong, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. Loeb, 2016: Earth radiation Budget at Top-of-Atmosphere [in “State of the Climate in 2015"]. Bull. Amer. Meteor. Soc., 97(S41-S43). doi: 10.1175/2016BAMSStateoftheClimate.1.
Stackhouse, P.; Kratz, D. P.; Wong, T.; Sawaengphokhai, P.; Wilber, A. C.; Gupta, SK; Loeb, N. G.Stackhouse, P., D. P. Kratz, T. Wong, P. Sawaengphokhai, A. C. Wilber, S. Gupta, N. G. Loeb, 2016: Earth radiation Budget at Top-of-Atmosphere [in “State of the Climate in 2015"]. Bull. Amer. Meteor. Soc., 97(8), S41-S43. doi: 10.1175/2016BAMSStateoftheClimate.1.
Xu, Kuan-Man; Wong, Takmeng; Dong, Shengtao; Chen, Feng; Kato, Seiji; Taylor, Patrick C.Xu, K., T. Wong, S. Dong, F. Chen, S. Kato, P. C. Taylor, 2016: Cloud Object Analysis of CERES Aqua Observations of Tropical and Subtropical Cloud Regimes: Four-Year Climatology. J. Climate, 29(5), 1617-1638. doi: 10.1175/JCLI-D-14-00836.1. Four distinct types of cloud objects—tropical deep convection, boundary layer cumulus, stratocumulus, and overcast stratus—were previously identified from CERES Tropical Rainfall Measuring Mission (TRMM) data. Six additional types of cloud objects—cirrus, cirrocumulus, cirrostratus, altocumulus, transitional altocumulus, and solid altocumulus—are identified from CERES Aqua satellite data in this study. The selection criteria for the 10 cloud object types are based on CERES footprint cloud fraction and cloud-top pressure, as well as cloud optical depth for the high-cloud types. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The data are analyzed according to cloud object types, sizes, regions, and associated environmental conditions. The frequency of occurrence and probability density functions (PDFs) of selected physical properties are produced for the July 2006–June 2010 period. It is found that deep convective and boundary layer types dominate the total population while the six new types other than cirrostratus do not contribute much in the tropics and subtropics. There are pronounced differences in the size spectrum between the types, with the largest ones being of deep convective type and with stratocumulus and overcast types over the ocean basins off west coasts. The summary PDFs of radiative and cloud physical properties differ greatly among the size categories. For boundary layer cloud types, the differences come primarily from the locations of cloud objects: for example, coasts versus open oceans. They can be explained by considerable variations in large-scale environmental conditions with cloud object size, which will be further qualified in future studies.
Smith, G.L.; Wong, Takmeng; Bush, K.A.Smith, G., T. Wong, K. Bush, 2015: Time-Sampling Errors of Earth Radiation From Satellites: Theory for Outgoing Longwave Radiation. IEEE Transactions on Geoscience and Remote Sensing, 53(3), 1656-1665. doi: 10.1109/TGRS.2014.2338793. The measurements of radiation budget by satellites in low Earth orbit provide limited sampling of the diurnal cycle. Thus, maps of monthly mean radiation fluxes contain errors due to this limitation. The Earth Radiation Budget Experiment reduced these errors in the data products by using a half-sine fit to account for regional diurnal cycles. An algorithm is presented to compute errors that are created when one computes the average value of outgoing longwave radiative flux (OLR) for a month based on the half-sine fit. Details of the temporal sampling are described by a sampling matrix that gives the number of OLR measurements in each local hour and each day of the month. The error analysis must take into account the correlation in time between irregularly spaced data due to synoptic variations, the weighting of measurements to accommodate the half-sine fit and deviations of the regional diurnal cycle from the half-sine. Using these ingredients, a closed-form expression is presented for the standard deviation of the temporal-sampling errors of the monthly mean OLR as computed from satellite measurements. The method is demonstrated for a well-sampled case and a poorly sampled case. This approach can be used to evaluate data products for existing measurements and for future mission design, or evaluating measurements of other atmospheric parameters. Earth; Extraterrestrial measurements; Remote sensing; atmospheric radiation; atmospheric techniques; Space vehicles; Time measurement; satellite measurements; Sea measurements; Orbits; earth radiation budget experiment; Error analysis; atmospheric parameters; Earth Radiation Budget Experiment (ERBE); half-sine fit; low Earth orbit; mission design; monthly mean radiation fluxes; OLR measurements; outgoing longwave radiative flux; radiation budget measurements; regional diurnal cycles; time-sampling error; time-sampling errors; Weight measurement
Wong, T; Kratz, D. P.; Stackhouse, P.W.; Sawaengphokhai, P.; Wilber, A. C.; Gupta, S. K.; Loeb, N. G.Wong, T., D. P. Kratz, P. Stackhouse, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2015: Earth radiation Budget at Top-of-Atmosphere [in “State of the Climate in 2014"]. Bull. Amer. Meteor. Soc., 96(7), S37-38. doi: 10.1175/2015BAMSStateoftheClimate.1.
Kratz, D. P.; Stackhouse Jr, PW; Wong, T; Wilber, A. C.; Sawaengphokhai, ParnchaiKratz, D. P., P. Stackhouse Jr, T. Wong, A. C. Wilber, P. Sawaengphokhai, 2014: Earth radiation Budget at Top-of-Atmosphere. Bull. Amer. Meteor. Soc., 95(7), S30-S32. doi: 10.1175/2014BAMSStateoftheClimate.1.
Rutan, David A.; Smith, G. Louis; Wong, TakmengRutan, D. A., G. L. Smith, T. Wong, 2014: Diurnal Variations of Albedo Retrieved from Earth Radiation Budget Experiment Measurements. J. Appl. Meteor. Climatol., 53(12), 2747-2760. doi: 10.1175/JAMC-D-13-0119.1. AbstractFive years of measurements from the Earth Radiation Budget Satellite (ERBS) have been analyzed to define the diurnal cycle of albedo from 55°N to 55°S. The ERBS precesses through all local times every 72 days so as to provide data regarding the diurnal cycles for Earth radiation. Albedo together with insolation at the top of the atmosphere is used to compute the heating of the Earth–atmosphere system; thus its diurnal cycle is important in the energetics of the climate system. A principal component (PC) analysis of the diurnal variation of top-of-atmosphere albedo using these data is presented. The analysis is done separately for ocean and land because of the marked differences of cloud behavior over ocean and over land. For ocean, 90%–92% of the variance in the diurnal cycle is described by a single component; for land, the first PC accounts for 83%–89% of the variance. Some of the variation is due to the increase of albedo with increasing solar zenith angle, which is taken into account in the ERBS data processing by a directional model, and some is due to the diurnal cycle of cloudiness. The second PC describes 2%–4% of the variance for ocean and 5% for land, and it is primarily due to variations of cloudiness throughout the day, which are asymmetric about noon. These terms show the response of the atmosphere to the cycle of solar heating. The third PC for ocean is a two-peaked curve, and the associated map shows high values in cloudy regions. Diurnal effects
Shrestha, Alok K.; Kato, Seiji; Wong, Takmeng; Rutan, David A.; Miller, Walter F.; Rose, Fred G.; Smith, G. Louis; Bedka, Kristopher M.; Minnis, Patrick; Fernandez, Jose R.Shrestha, A. K., S. Kato, T. Wong, D. A. Rutan, W. F. Miller, F. G. Rose, G. L. Smith, K. M. Bedka, P. Minnis, J. R. Fernandez, 2014: Unfiltering Earth Radiation Budget Experiment (ERBE) Scanner Radiances Using the CERES Algorithm and Its Evaluation with Nonscanner Observations. J. Atmos. Oceanic Technol., 31(4), 843-859. doi: 10.1175/JTECH-D-13-00072.1. AbstractThe NOAA-9 Earth Radiation Budget Experiment (ERBE) scanner measured broadband shortwave, longwave, and total radiances from February 1985 through January 1987. These scanner radiances are reprocessed using the more recent Clouds and the Earth’s Radiant Energy System (CERES) unfiltering algorithm. The scene information, including cloud properties, required for reprocessing is derived using Advanced Very High Resolution Radiometer (AVHRR) data on board NOAA-9, while no imager data were used in the original ERBE unfiltering. The reprocessing increases the NOAA-9 ERBE scanner unfiltered longwave radiances by 1.4%–2.0% during daytime and 0.2%–0.3% during nighttime relative to those derived from the ERBE unfiltering algorithm. Similarly, the scanner unfiltered shortwave radiances increase by ~1% for clear ocean and land and decrease for all-sky ocean, land, and snow/ice by ~1%. The resulting NOAA-9 ERBE scanner unfiltered radiances are then compared with NOAA-9 nonscanner irradiances by integrating the ERBE scanner radiance over the nonscanner field of view. The comparison indicates that the integrated scanner radiances are larger by 0.9% for shortwave and 0.7% smaller for longwave. A sensitivity study shows that the one-standard-deviation uncertainties in the agreement are ±2.5%, ±1.2%, and ±1.8% for the shortwave, nighttime longwave, and daytime longwave irradiances, respectively. The NOAA-9 and ERBS nonscanner irradiances are also compared using 2 years of data. The comparison indicates that the NOAA-9 nonscanner shortwave, nighttime longwave, and daytime longwave irradiances are 0.3% larger, 0.6% smaller, and 0.4% larger, respectively. The longer observational record provided by the ERBS nonscanner plays a critical role in tying the CERES-like NOAA-9 ERBE scanner dataset from the mid-1980s to the present-day CERES scanner data record. Remote sensing; satellite observations; Climate records; Filtering techniques
Shrestha, A. K., S. Kato, K. M. Bedka, W. F. Miller, T. Wong, D. A. Rutan, G. L. Smith, J. R. Fernandez, N. Loeb, P. Minnis, and D. R. DoellingShrestha, A. K., S. Kato, K. M. Bedka, W. F. Miller, T. Wong, D. A. Rutan, G. L. Smith, J. R. Fernandez, N. Loeb, P. Minnis, and D. R. Doelling, 2013: Earth Radiation Budget Experiment (ERBE) Reprocessing using Clouds and the Earth’s Radiant Energy System (CERES) Angular Distribution Models. 2012 International Radiation Symposium – Radiation Processes in the Atmosphere and Ocean, 1531(712). doi: 10.1063/1.4804869.
Stackhouse Jr., P. W., T. Wong, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. LoebStackhouse Jr., P. W., T. Wong, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, and N. G. Loeb, 2013: Earth Radiation Budget at Top-of-atmosphere [in "State of the Climate in 2012"]. Bull. Amer. Meteor. Soc., 94(8). doi: 10.1175/2013BAMSStateoftheClimate.1.
Stackhouse, P.W.; Wong, T; Kratz, D. P.; Sawaengphokhai, P.; Wilber, A. C.; Gupta, S. K.; Loeb, N. G.Stackhouse, P., T. Wong, D. P. Kratz, P. Sawaengphokhai, A. C. Wilber, S. K. Gupta, N. G. Loeb, 2013: Earth radiation Budget at Top-of-Atmosphere [in “State of the Climate in 2012"]. Bull. Amer. Meteor. Soc., 94(8), S41-S43. doi: 10.1175/2013BAMSStateoftheClimate.1.
Loeb, Norman G.; Kato, Seiji; Su, Wenying; Wong, Takmeng; Rose, Fred G.; Doelling, David R.; Norris, Joel R.; Huang, XiangleiLoeb, N. G., S. Kato, W. Su, T. Wong, F. G. Rose, D. R. Doelling, J. R. Norris, X. Huang, 2012: Advances in Understanding Top-of-Atmosphere Radiation Variability from Satellite Observations. Surveys in Geophysics, 33(3-4), 359-385. doi: 10.1007/s10712-012-9175-1. This paper highlights how the emerging record of satellite observations from the Earth Observation System (EOS) and A-Train constellation are advancing our ability to more completely document and understand the underlying processes associated with variations in the Earth’s top-of-atmosphere (TOA) radiation budget. Large-scale TOA radiation changes during the past decade are observed to be within 0.5 Wm−2 per decade based upon comparisons between Clouds and the Earth’s Radiant Energy System (CERES) instruments aboard Terra and Aqua and other instruments. Tropical variations in emitted outgoing longwave (LW) radiation are found to closely track changes in the El Niño-Southern Oscillation (ENSO). During positive ENSO phase (El Niño), outgoing LW radiation increases, and decreases during the negative ENSO phase (La Niña). The coldest year during the last decade occurred in 2008, during which strong La Nina conditions persisted throughout most of the year. Atmospheric Infrared Sounder (AIRS) observations show that the lower temperatures extended throughout much of the troposphere for several months, resulting in a reduction in outgoing LW radiation and an increase in net incoming radiation. At the global scale, outgoing LW flux anomalies are partially compensated for by decreases in midlatitude cloud fraction and cloud height, as observed by Moderate Resolution Imaging Spectrometer and Multi-angle Imaging SpectroRadiometer, respectively. CERES data show that clouds have a net radiative warming influence during La Niña conditions and a net cooling influence during El Niño, but the magnitude of the anomalies varies greatly from one ENSO event to another. Regional cloud-radiation variations among several Terra and A-Train instruments show consistent patterns and exhibit marked fluctuations at monthly timescales in response to tropical atmosphere-ocean dynamical processes associated with ENSO and Madden–Julian Oscillation. clouds; radiation budget; Geophysics/Geodesy; Astronomy, Observations and Techniques; Earth Sciences, general; Climate variability
Loeb, Norman G.; Lyman, John M.; Johnson, Gregory C.; Allan, Richard P.; Doelling, David R.; Wong, Takmeng; Soden, Brian J.; Stephens, Graeme L.Loeb, N. G., J. M. Lyman, G. C. Johnson, R. P. Allan, D. R. Doelling, T. Wong, B. J. Soden, G. L. Stephens, 2012: Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty. Nature Geoscience, 5(2), 110-113. doi: 10.1038/ngeo1375. Global climate change results from a small yet persistent imbalance between the amount of sunlight absorbed by Earth and the thermal radiation emitted back to space. An apparent inconsistency has been diagnosed between interannual variations in the net radiation imbalance inferred from satellite measurements and upper-ocean heating rate from in situ measurements, and this inconsistency has been interpreted as ‘missing energy’ in the system. Here we present a revised analysis of net radiation at the top of the atmosphere from satellite data, and we estimate ocean heat content, based on three independent sources. We find that the difference between the heat balance at the top of the atmosphere and upper-ocean heat content change is not statistically significant when accounting for observational uncertainties in ocean measurements, given transitions in instrumentation and sampling. Furthermore, variability in Earth’s energy imbalance relating to El Niño-Southern Oscillation is found to be consistent within observational uncertainties among the satellite measurements, a reanalysis model simulation and one of the ocean heat content records. We combine satellite data with ocean measurements to depths of 1,800 m, and show that between January 2001 and December 2010, Earth has been steadily accumulating energy at a rate of 0.50±0.43 Wm−2 (uncertainties at the 90% confidence level). We conclude that energy storage is continuing to increase in the sub-surface ocean. Oceanography; Atmospheric science; Climate science
Wong, T. M.; Stackhouse Jr, PW; Kratz, D. P.; Wilber, A. C.; Loeb, N. GWong, T. M., P. Stackhouse Jr, D. P. Kratz, A. C. Wilber, N. G. Loeb, 2012: Earth Radiation Budget at Top-of-atmosphere [in "State of the Climate in 2011"]. Bull. Amer. Meteor. Soc., 93(7), S38-S40. doi: 10.1175/2012BAMSStateoftheClimate.1.
Wong, T. M.; Stackhouse Jr, PW; Kratz, D. P.; Wilber, A. C.; Loeb, N. GWong, T. M., P. Stackhouse Jr, D. P. Kratz, A. C. Wilber, N. G. Loeb, 2012: Earth Radiation Budget at Top-of-atmosphere [in "State of the Climate in 2011"]. Bull. Amer. Meteor. Soc., 93(7), S38-S40. doi: 10.1175/2012BAMSStateoftheClimate.1.
Wong, T., W. B. Rossow, Y. C. Zhang, L. Hinkelman, E. Raschke, S. Kinne, J. Russell, R. Bantges, R. Roca, G. L. Smith, and N. LoebWong, T., W. B. Rossow, Y. C. Zhang, L. Hinkelman, E. Raschke, S. Kinne, J. Russell, R. Bantges, R. Roca, G. L. Smith, and N. Loeb, 2012: Chapter 3: Radiative Fluxes at the Top-of-the-Atmosphere (TOA) [in "GEWEX Radiative Flux Assessment (RFA), Volume 1: Assessment"]. Chapter 3: Radiative Fluxes at the Top-of-the-Atmosphere (TOA) [in "GEWEX Radiative Flux Assessment (RFA), Volume 1: Assessment"], 19/2012(23-90).
Eitzen, Zachary A.; Xu, Kuan-Man; Wong, TakmengEitzen, Z. A., K. Xu, T. Wong, 2011: An Estimate of Low-Cloud Feedbacks from Variations of Cloud Radiative and Physical Properties with Sea Surface Temperature on Interannual Time Scales. J. Climate, 24(4), 1106-1121. doi: 10.1175/2010JCLI3670.1. Abstract Simulations of climate change have yet to reach a consensus on the sign and magnitude of the changes in physical properties of marine boundary layer clouds. In this study, the authors analyze how cloud and radiative properties vary with SST anomaly in low-cloud regions, based on five years (March 2000–February 2005) of Clouds and the Earth’s Radiant Energy System (CERES)–Terra monthly gridded data and matched European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological reanalaysis data. In particular, this study focuses on the changes in cloud radiative effect, cloud fraction, and cloud optical depth with SST anomaly. The major findings are as follows. First, the low-cloud amount (−1.9% to −3.4% K−1) and the logarithm of low-cloud optical depth (−0.085 to −0.100 K−1) tend to decrease while the net cloud radiative effect (3.86 W m−2 K−1) becomes less negative as SST anomalies increase. These results are broadly consistent with previous observational studies. Second, after the changes in cloud and radiative properties with SST anomaly are separated into dynamic, thermodynamic, and residual components, changes in the dynamic component (taken as the vertical velocity at 700 hPa) have relatively little effect on cloud and radiative properties. However, the estimated inversion strength decreases with increasing SST, accounting for a large portion of the measured decreases in cloud fraction and cloud optical depth. The residual positive change in net cloud radiative effect (1.48 W m−2 K−1) and small changes in low-cloud amount (−0.81% to 0.22% K−1) and decrease in the logarithm of optical depth (–0.035 to –0.046 K−1) with SST are interpreted as a positive cloud feedback, with cloud optical depth feedback being the dominant contributor. Last, the magnitudes of the residual changes differ greatly among the six low-cloud regions examined in this study, with the largest positive feedbacks (∼4 W m−2 K−1) in the southeast and northeast Atlantic regions and a slightly negative feedback (−0.2 W m−2 K−1) in the south-central Pacific region. Because the retrievals of cloud optical depth and/or cloud fraction are difficult in the presence of aerosols, the transport of heavy African continental aerosols may contribute to the large magnitudes of estimated cloud feedback in the two Atlantic regions. Feedback; sea surface temperature; Optical properties; Cloud radiative effects; Interannual variability
Kratz, D. P.; Stackhouse, P.W.; Wong, T; Sawaengphokhai, P.; Wilber, A. C.; Loeb, N. G.Kratz, D. P., P. Stackhouse, T. Wong, P. Sawaengphokhai, A. C. Wilber, N. G. Loeb, 2011: Earth Radiation Budget at top-of-atmosphere in 'State of the Climate 2010'. Bulletin of the American Meterological Society, 92(6). doi: 10.1175/1520-0477-92.6.S1.
Stackhouse Jr, PW; Wong, T.; Loeb, N. G; Kratz, D. P.; Wilber, A. C.; Doelling, D. R.; Nguyen, L. CathyStackhouse Jr, P., T. Wong, N. G. Loeb, D. P. Kratz, A. C. Wilber, D. R. Doelling, L. C. Nguyen, 2010: Earth Radiation Budget at top-of-atmosphere [in "State of the Climate in 2009”]. Bull. Amer. Meteor. Soc., 91(7), S41. doi: 10.1175/BAMS-91-7-StateoftheClimate.
Trenberth, Kevin E.; Fasullo, John T.; O'Dell, Chris; Wong, TakmengTrenberth, K. E., J. T. Fasullo, C. O'Dell, T. Wong, 2010: Relationships between tropical sea surface temperature and top-of-atmosphere radiation. Geophysical Research Letters, 37(3), L03702. doi: 10.1029/2009GL042314. To assess climate sensitivity from Earth radiation observations of limited duration and observed sea surface temperatures (SSTs) requires a closed and therefore global domain, equilibrium between the fields, and robust methods of dealing with noise. Noise arises from natural variability in the atmosphere and observational noise in precessing satellite observations. This paper explores the meaning of results that use only the tropical region. We compute correlations and regressions between tropical SSTs and top-of-atmosphere (TOA) longwave, shortwave and net radiation using a variety of methods to test robustness of results. The main changes in SSTs throughout the tropics are associated with El Niño Southern Oscillation (ENSO) events in which the dominant changes in energy into an atmospheric column come from ocean heat exchange through evaporation, latent heat release in precipitation, and redistribution of that heat through atmospheric winds. These changes can be an order of magnitude larger than the net TOA radiation changes, and their effects are teleconnected globally, and especially into the subtropics. Atmospheric model results are explored and found to be consistent with observations. From 1985 to 1999 the largest perturbation in TOA radiative fluxes was from the eruption of Mount Pinatubo and clearly models which do not include that forcing will not simulate the effects. Consequently, regressions of radiation with SSTs in the tropics may have nothing to say about climate sensitivity. 1610 Atmosphere; 1620 Climate dynamics; 0321 Cloud/radiation interaction; climate; radiation; 1626 Global climate models; temperatures
Andronova, Natalia; Penner, Joyce E.; Wong, TakmengAndronova, N., J. E. Penner, T. Wong, 2009: Observed and modeled evolution of the tropical mean radiation budget at the top of the atmosphere since 1985. Journal of Geophysical Research: Atmospheres, 114(D14), D14106. doi: 10.1029/2008JD011560. We have used satellite-based broadband radiation observations to construct a long-term continuous 1985–2005 record of the radiative budget components at the top of the atmosphere for the tropical region (20°S–20°N). On the basis of the constructed record we have derived the most conservative estimate of their trends. We compared the interannual variability of the net radiative fluxes at the top of the tropical atmosphere with model simulations from the Intergovernmental Panel on Climate Change fourth assessment report (AR4) archive available up to 2000 and showed that most of the models capture the 1991 Mount Pinatubo eruption signal in both its timing and amplitude; however, none of them simulate the observed trends. Further comparison showed that among the “best skilled” models, which are those that showed the highest value of the correlation in simulating one or all of the observed net, shortwave, and longwave radiative fluxes at the top of the atmosphere, the model with an equilibrium climate sensitivity ∼3.4°C for the doubling CO2 represents the observed amplifying total feedback effect in the tropical atmosphere better than the models with a climate sensitivity ∼2.7°C or 4.3°C. This total feedback effect was calculated on the basis of an assumed simplified system of interactions between the near-surface temperature and the net radiation at the top of the atmosphere. 3359 Radiative processes; 0325 Evolution of the atmosphere; 3305 Climate change and variability; 3337 Global climate models; 3374 Tropical meteorology; feedbacks; radiative forcing; tropical atmosphere
Eitzen, Zachary A.; Xu, Kuan-Man; Wong, TakmengEitzen, Z. A., K. Xu, T. Wong, 2009: Cloud and Radiative Characteristics of Tropical Deep Convective Systems in Extended Cloud Objects from CERES Observations. J. Climate, 22(22), 5983-6000. doi: 10.1175/2009JCLI3038.1. Abstract The physical and radiative properties of tropical deep convective systems for the period from January to August 1998 are examined with the use of Clouds and the Earth’s Radiant Energy System Single-Scanner Footprint (SSF) data from the Tropical Rainfall Measuring Mission satellite. Deep convective (DC) cloud objects are contiguous regions of satellite footprints that fulfill the DC criteria (i.e., overcast footprints with cloud optical depths >10 and cloud-top heights >10 km). Extended cloud objects (ECOs) start with the original cloud object but include all other cloudy footprints within a rectangular box that completely covers the original cloud object. Most of the non-DC footprints are overcast but have optical depths and/or cloud-top heights that are too low to fit the DC criteria. The histograms of cloud physical and radiative properties are analyzed according to the size of the ECO and the SST of the underlying ocean. Larger ECOs are associated with greater magnitudes of large-scale upward motion, which supports stronger convection for larger sizes of ECOs. This leads to shifts toward higher values in the DC distributions of cloud-top height, albedo, condensate water path, and cloud optical depth. However, non-DC footprints become less reflective with increasing ECO size, as the longer-lived large convective systems have more time to develop thin cirrus anvils. The proportion of DC footprints remains fairly constant with size. The proportion of DC footprints also remains nearly constant with SST within a given size class, although the number of footprints per object increases with SST for large objects. As SSTs increase, there is a decrease in the proportion of updraft water that goes into detrainment, causing the non-DC distributions of albedo, condensate water path, and cloud optical depth to shift toward lower values. The all-cloud distributions of cloud-top temperature and outgoing longwave radiation (OLR) shift toward lower values as SST increases owing to the increase in convective instability with SST. Both the DC and non-DC distributions of cloud-top temperature do not change much with satellite precession cycle, supporting the fixed anvil temperature hypothesis of Hartmann and Larson. When a joint histogram is formed from the cloud-top pressures and cloud optical depths of the ECOs, it is very similar to the corresponding histogram of the deep convective weather state obtained by cluster analysis of International Satellite Cloud Climatology Project data. convection; Cloud microphysics; Radiative fluxes; sea surface temperature; Updrafts
Loeb, Norman G.; Wielicki, Bruce A.; Doelling, David R.; Smith, G. Louis; Keyes, Dennis F.; Kato, Seiji; Manalo-Smith, Natividad; Wong, TakmengLoeb, N. G., B. A. Wielicki, D. R. Doelling, G. L. Smith, D. F. Keyes, S. Kato, N. Manalo-Smith, T. Wong, 2009: Toward Optimal Closure of the Earth's Top-of-Atmosphere Radiation Budget. J. Climate, 22(3), 748-766. doi: 10.1175/2008JCLI2637.1. Abstract Despite recent improvements in satellite instrument calibration and the algorithms used to determine reflected solar (SW) and emitted thermal (LW) top-of-atmosphere (TOA) radiative fluxes, a sizeable imbalance persists in the average global net radiation at the TOA from satellite observations. This imbalance is problematic in applications that use earth radiation budget (ERB) data for climate model evaluation, estimate the earth’s annual global mean energy budget, and in studies that infer meridional heat transports. This study provides a detailed error analysis of TOA fluxes based on the latest generation of Clouds and the Earth’s Radiant Energy System (CERES) gridded monthly mean data products [the monthly TOA/surface averages geostationary (SRBAVG-GEO)] and uses an objective constrainment algorithm to adjust SW and LW TOA fluxes within their range of uncertainty to remove the inconsistency between average global net TOA flux and heat storage in the earth–atmosphere system. The 5-yr global mean CERES net flux from the standard CERES product is 6.5 W m−2, much larger than the best estimate of 0.85 W m−2 based on observed ocean heat content data and model simulations. The major sources of uncertainty in the CERES estimate are from instrument calibration (4.2 W m−2) and the assumed value for total solar irradiance (1 W m−2). After adjustment, the global mean CERES SW TOA flux is 99.5 W m−2, corresponding to an albedo of 0.293, and the global mean LW TOA flux is 239.6 W m−2. These values differ markedly from previously published adjusted global means based on the ERB Experiment in which the global mean SW TOA flux is 107 W m−2 and the LW TOA flux is 234 W m−2. Radiation budgets; satellite observations; Fluxes
Loeb, Norman G.; Wielicki, Bruce A.; Wong, Takmeng; Parker, Peter A.Loeb, N. G., B. A. Wielicki, T. Wong, P. A. Parker, 2009: Impact of data gaps on satellite broadband radiation records. Journal of Geophysical Research: Atmospheres, 114(D11), D11109. doi: 10.1029/2008JD011183. A simulated 30-year climate data record of net cloud radiative effect (defined as the difference between clear- and all-sky net top-of-atmosphere radiative flux) based on the first 5 years of Clouds and the Earth's Radiant Energy System (CERES) Terra measurements is created in order to investigate how gaps in the record affect our ability to constrain cloud radiative feedback. To ensure a trend estimate with an uncertainty small enough to constrain cloud radiative feedback to 25% of anthropogenic forcing in the next few decades, the absolute calibration change across the gap must be 0321 Cloud/radiation interaction; 3305 Climate change and variability; 1616 Climate variability; radiation; overlap; gaps
Murphy, D. M.; Solomon, S.; Portmann, R. W.; Rosenlof, K. H.; Forster, P. M.; Wong, T.Murphy, D. M., S. Solomon, R. W. Portmann, K. H. Rosenlof, P. M. Forster, T. Wong, 2009: An observationally based energy balance for the Earth since 1950. Journal of Geophysical Research: Atmospheres, 114(D17), D17107. doi: 10.1029/2009JD012105. We examine the Earth's energy balance since 1950, identifying results that can be obtained without using global climate models. Important terms that can be constrained using only measurements and radiative transfer models are ocean heat content, radiative forcing by long-lived trace gases, and radiative forcing from volcanic eruptions. We explicitly consider the emission of energy by a warming Earth by using correlations between surface temperature and satellite radiant flux data and show that this term is already quite significant. About 20% of the integrated positive forcing by greenhouse gases and solar radiation since 1950 has been radiated to space. Only about 10% of the positive forcing (about 1/3 of the net forcing) has gone into heating the Earth, almost all into the oceans. About 20% of the positive forcing has been balanced by volcanic aerosols, and the remaining 50% is mainly attributable to tropospheric aerosols. After accounting for the measured terms, the residual forcing between 1970 and 2000 due to direct and indirect forcing by aerosols as well as semidirect forcing from greenhouse gases and any unknown mechanism can be estimated as −1.1 ± 0.4 W m−2 (1σ). This is consistent with the Intergovernmental Panel on Climate Change's best estimates but rules out very large negative forcings from aerosol indirect effects. Further, the data imply an increase from the 1950s to the 1980s followed by constant or slightly declining aerosol forcing into the 1990s, consistent with estimates of trends in global sulfate emissions. An apparent increase in residual forcing in the late 1990s is discussed. 0305 Aerosols and particles; climate change; radiative forcing; 1616 Climate variability; 1626 Global climate models; 1635 Oceans
Wong, T.; Stackhouse Jr, PW; Kratz, D. P.; Wilber, A. C.Wong, T., P. Stackhouse Jr, D. P. Kratz, A. C. Wilber, 2009: Earth Radiation Budget at top-of-atmosphere [in "State of the Climate in 2008"]. Bull. Amer. Meteor. Soc.. doi: 10.1175/BAMS-90-8-StateoftheClimate.
Eitzen, ZA; Xu, KM; Wong, TEitzen, Z., K. Xu, T. Wong, 2008: Statistical Analyses of Satellite Cloud Object Data from CERES. Part V: Relationships between Physical Properties of Marine Boundary Layer Clouds. JOURNAL OF CLIMATE, 21(24), 6668-6688. doi: 10.1175/2008JCLI2307.1. Relationships between physical properties are studied for three types of marine boundary layer cloud objects identified with the Clouds and the Earth's Radiant Energy System (CERES) footprint data from the Tropical Rainfall Measuring Mission satellite between 30 degrees S and 30 degrees N. Each cloud object is a contiguous region of CERES footprints that have cloud-top heights below 3 km, and cloud fractions of 99%-100% (overcast type), 40%-99% (stratocumulus type), or 10%-40% (shallow cumulus type). These cloud fractions represent the fraction of similar to 2 km x 2 km Visible/Infrared Scanner pixels that are cloudy within each similar to 10 km x 10 km footprint. The cloud objects have effective diameters that are greater than 300 km for the overcast and stratocumulus types, and greater than 150 km for the shallow cumulus type. The Spearman rank correlation coefficient is calculated between many microphysical/optical [effective radius (r(e)), cloud optical depth (tau), albedo, liquid water path, and shortwave cloud radiative forcing (SW CRF)] and macrophysical [outgoing longwave radiation (OLR), cloud fraction, cloud-top temperature, longwave cloud radiative forcing (LW CRF), and sea surface temperature (SST)] properties for each of the three cloud object types. When both physical properties are of the same category (microphysical/optical or macrophysical), the magnitude of the correlation tends to be higher than when they are from different categories. The magnitudes of the correlations also change with cloud object type, with the correlations for overcast and stratocumulus cloud objects tending to be higher than those for shallow cumulus cloud objects. Three pairs of physical properties are studied in detail, using a k-means cluster analysis: r(e) and tau, OLR and SST, and LW CRF and SW CRF. The cluster analysis of r(e) and tau reveals that for each of the cloud types, there is a cluster of cloud objects with negative slopes, a cluster with slopes near zero, and two clusters with positive slopes. The joint OLR and SST probability plots show that the OLR tends to decrease with SST in regions with boundary layer clouds for SSTs above approximately 298 K. When the cloud objects are split into "dry" and "moist" clusters based on the amount of precipitable water above 700 hPa, the associated OLRs increase with SST throughout the SST range for the dry clusters, but the OLRs are roughly constant with SST for the moist cluster. An analysis of the joint PDFs of LW CRF and SW CRF reveals that while the magnitudes of both LW and SW CRFs generally increase with cloud fraction, there is a cluster of overcast cloud objects that has low values of LW and SW CRF. These objects are generally located near the Sahara Desert, and may be contaminated with dust. Many of these overcast objects also appear in the re and tau cluster with negative slopes.
Lee, R. B. III, G. L. Smith, T. Wong, K. A. BushLee, R. B. III, G. L. Smith, T. Wong, K. A. Bush, 2008: 1999-2003 shortwave characterizations of Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) broadband active cavity radiometer sensors. SPIE Proceedings, Earth Observing Systems XIII, 7081. doi: 10.1117/12.797109.
Smith, G. L., P. E. Mlynczak, D. A. Rutan, and T. WongSmith, G. L., P. E. Mlynczak, D. A. Rutan, and T. Wong, 2008: Comparison of the Diurnal Cycle of Outgoing Longwave Radiation from a Climate Model with Results from ERBE. J. Appl. Meteor. Climatol., 47(3188-3202). doi: 10.1175/2008JAMC1924.1.
Smith, G. L., R. B. Lee III, T. Wong, P. E. MlynczakSmith, G. L., R. B. Lee III, T. Wong, P. E. Mlynczak, 2008: Degradation pattern of the ERBE wide field-of-view radiometer aboard the NOAA 9 spacecraft. SPIE Proceedings, Sensors, Systems, and Next-Generation Satellites XII, 7106. doi: 10.1117/12.799637.
Wong, T., and B. A. WielickiWong, T., and B. A. Wielicki, 2008: Unscrambling the Cause of the Recent Ocean Cooling with Net Radiation Observations from the CERES Instrument on the Terra Satellite. The Earth Observer, 20, 1(16-19).
Xu, K. M.; Wong, T.; Wielicki, B. A.; Parker, L.Xu, K. M., T. Wong, B. A. Wielicki, L. Parker, 2008: Statistical analyses of satellite cloud object data from CERES. Part IV: Boundary layer cloud objects during 1998 El Nino. J. Climate, 21(7), 1500-1521. doi: 10.1175/2007jcli1710.1. Three boundary layer cloud object types-overcast, stratocumulus, and cumulus-that occurred over the Pacific Ocean during January-August 1998 are identified from the Clouds and the Earth's Radiant Energy System (CERES) single scanner footprint data. Characteristics of each cloud object type matched with atmospheric states are examined for large regions in the tropics and subtropics and for different size categories. Stratocumulus cloud objects dominate the entire boundary layer cloud population in all regions and size categories. Overcast cloud objects, which have the largest average size, are more prevalent in the subtropics and near the coastal regions, while cumulus cloud objects are prevalent over the open oceans and the equatorial regions, particularly within the small-size categories. Cloud objects with equivalent diameters less than 75 km are excluded in the analysis. The differences between the tropical and subtropical statistical distributions of cloud properties are small for liquid water path (LWP), cloud optical depth, and top-of-the-atmosphere (TOA) albedo, but large for cloud-top temperature and outgoing longwave radiation (OLR), for each of the three cloud object types. The larger cloud objects have higher LWPs, cloud optical depths, TOA albedos, and OLRs, but lower SSTs and cloud-top heights for the stratocumulus and overcast types. Lower-tropospheric stability seems to be the primary factor for the differences in the distributions of cloud physical properties between the regions or between the size categories. Atmospheric dynamics also play a role in determining the differences in the distributions of cloud physical properties between the size categories, but not a significant role for those between the types or between the regions. The latter may be due to uncertainties in the matched vertical velocity data. When the three cloud object types are combined in small regions, lower-tropospheric stability determines the transition of boundary layer cloud types along a Pacific transect. The proportion of each type is the most important factor for diagnosing the combined cloud properties along this transect, such as LWP, cloud optical depth, and TOA albedo. Atmospheric dynamics also play complicated roles in determining the combined cloud properties along this transect.
Loeb, N. G. and T. WongLoeb, N. G. and T. Wong, 2007: Clouds and the Earth's Radiation Budget. Our Changing Planet, The View from Space. M. D. King, C. L. Parkinson, K. C. Partington, and R. G. Williams (eds.), Cambridge University Press, 21-25.
Loeb, Norman G.; Wielicki, Bruce A.; Su, Wenying; Loukachine, Konstantin; Sun, Wenbo; Wong, Takmeng; Priestley, Kory J.; Matthews, Grant; Miller, Walter F.; Davies, R.Loeb, N. G., B. A. Wielicki, W. Su, K. Loukachine, W. Sun, T. Wong, K. J. Priestley, G. Matthews, W. F. Miller, R. Davies, 2007: Multi-Instrument Comparison of Top-of-Atmosphere Reflected Solar Radiation. J. Climate, 20(3), 575-591. doi: 10.1175/JCLI4018.1. Abstract Observations from the Clouds and the Earth’s Radiant Energy System (CERES), Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) between 2000 and 2005 are analyzed in order to determine if these data are meeting climate accuracy goals recently established by the climate community. The focus is primarily on top-of-atmosphere (TOA) reflected solar radiances and radiative fluxes. Direct comparisons of nadir radiances from CERES, MODIS, and MISR aboard the Terra satellite reveal that the measurements from these instruments exhibit a year-to-year relative stability of better than 1%, with no systematic change with time. By comparison, the climate requirement for the stability of visible radiometer measurements is 1% decade−1. When tropical ocean monthly anomalies in shortwave (SW) TOA radiative fluxes from CERES on Terra are compared with anomalies in Photosynthetically Active Radiation (PAR) from SeaWiFS—an instrument whose radiance stability is better than 0.07% during its first six years in orbit—the two are strongly anticorrelated. After scaling the SeaWiFS anomalies by a constant factor given by the slope of the regression line fit between CERES and SeaWiFS anomalies, the standard deviation in the difference between monthly anomalies from the two records is only 0.2 W m−2, and the difference in their trend lines is only 0.02 ± 0.3 W m−2 decade−1, approximately within the 0.3 W m−2 decade−1 stability requirement for climate accuracy. For both the Tropics and globe, CERES Terra SW TOA fluxes show no trend between March 2000 and June 2005. Significant differences are found between SW TOA flux trends from CERES Terra and CERES Aqua between August 2002 and March 2005. This discrepancy is due to uncertainties in the adjustment factors used to account for degradation of the CERES Aqua optics during hemispheric scan mode operations. Comparisons of SW TOA flux between CERES Terra and the International Satellite Cloud Climatology Project (ISCCP) radiative flux profile dataset (FD) RadFlux product show good agreement in monthly anomalies between January 2002 and December 2004, and poor agreement prior to this period. Commonly used statistical tools applied to the CERES Terra data reveal that in order to detect a statistically significant trend of magnitude 0.3 W m−2 decade−1 in global SW TOA flux, approximately 10 to 15 yr of data are needed. This assumes that CERES Terra instrument calibration remains highly stable, long-term climate variability remains constant, and the Terra spacecraft has enough fuel to last 15 yr. satellite observations; radiative forcing; Shortwave radiation
Luo, Yali; Xu, Kuan-Man; Wielicki, Bruce A.; Wong, Takmeng; Eitzen, Zachary A.Luo, Y., K. Xu, B. A. Wielicki, T. Wong, Z. A. Eitzen, 2007: Statistical Analyses of Satellite Cloud Object Data from CERES. Part III: Comparison with Cloud-Resolving Model Simulations of Tropical Convective Clouds. J. Atmos. Sci., 64(3), 762-785. doi: 10.1175/JAS3871.1. Abstract The present study evaluates the ability of a cloud-resolving model (CRM) to simulate the physical properties of tropical deep convective cloud objects identified from a Clouds and the Earth’s Radiant Energy System (CERES) data product. The emphasis of this study is the comparisons among the small-, medium-, and large-size categories of cloud objects observed during March 1998 and between the large-size categories of cloud objects observed during March 1998 (strong El Niño) and March 2000 (weak La Niña). Results from the CRM simulations are analyzed in a way that is consistent with the CERES retrieval algorithm and they are averaged to match the scale of the CERES satellite footprints. Cloud physical properties are analyzed in terms of their summary histograms for each category. It is found that there is a general agreement in the overall shapes of all cloud physical properties between the simulated and observed distributions. Each cloud physical property produced by the CRM also exhibits different degrees of disagreement with observations over different ranges of the property. The simulated cloud tops are generally too high and cloud-top temperatures are too low except for the large-size category of March 1998. The probability densities of the simulated top-of-the-atmosphere (TOA) albedos for all four categories are underestimated for high albedos, while those of cloud optical depth are overestimated at its lowest bin. These disagreements are mainly related to uncertainties in the cloud microphysics parameterization and inputs such as cloud ice effective size to the radiation calculation. Summary histograms of cloud optical depth and TOA albedo from the CRM simulations of the large-size category of cloud objects do not differ significantly between the March 1998 and 2000 periods, consistent with the CERES observations. However, the CRM is unable to reproduce the significant differences in the observed cloud-top height while it overestimates the differences in the observed outgoing longwave radiation and cloud-top temperature between the two periods. Comparisons between the CRM results and the observations for most parameters in March 1998 consistently show that both the simulations and observations have larger differences between the large- and small-size categories than between the large- and medium-size, or between the medium- and small-size categories. However, the simulated cloud properties do not change as much with size as observed. These disagreements are likely related to the spatial averaging of the forcing data and the mismatch in time and space between the numerical weather prediction model from which the forcing data are produced and the CERES observed cloud systems. cloud-resolving models; Cloud microphysics; satellite observations; convective clouds; statistics
Xu, K. M.; Wong, T.; Wielicki, B. A.; Parker, L.; Lin, B.; Eitzen, Z. A.; Branson, M.Xu, K. M., T. Wong, B. A. Wielicki, L. Parker, B. Lin, Z. A. Eitzen, M. Branson, 2007: Statistical analyses of satellite cloud object data from CERES. Part II: Tropical convective cloud objects during 1998 El Nino and evidence for supporting the fixed anvil temperature hypothesis. J. Climate, 20(5), 819-842. doi: 10.1175/jcli4069.1. Characteristics of tropical deep convective cloud objects observed over the tropical Pacific during January-August 1998 are examined using the Tropical Rainfall Measuring Mission/Clouds and the Earth's Radiant Energy System Single Scanner Footprint (SSF) data. These characteristics include the frequencies of occurrence and statistical distributions of cloud physical properties. Their variations with cloud object size, sea surface temperature (SST), and satellite precession cycle are analyzed in detail. A cloud object is defined as a contiguous patch of the earth composed of satellite footprints within a single dominant cloud-system type. It is found that statistical distributions of cloud physical properties are significantly different among three size categories of cloud objects with equivalent diameters of 100-150 (small), 150-300 (medium), and > 300 km (large), except for the distributions of ice particle size. The distributions for the larger-size category of cloud objects are more skewed toward high SSTs, high cloud tops, low cloud-top temperature, large ice water path, high cloud optical depth, low outgoing longwave (LW) radiation, and high albedo than the smaller-size category. As SST varied from one satellite precession cycle to another, the changes in macrophysical properties of cloud objects over the entire tropical Pacific were small for the large-size category of cloud objects, relative to those of the small- and medium-size categories. This evidence supports the fixed anvil temperature hypothesis of Hartmann and Larson for the large-size category. Combined with the result that a higher percentage of the large-size category of cloud objects occurs during higher SST subperiods, this implies that macro-physical properties of cloud objects would be less sensitive to further warming of the climate. On the other hand, when cloud objects are classified according to SST ranges, statistical characteristics of cloud microphysical properties, optical depth, and albedo are not sensitive to the SST, but those of cloud macrophysical properties are dependent upon the SST. This result is related to larger differences in large-scale dynamics among the SST ranges than among the satellite precession cycles. Frequency distributions of vertical velocity from the European Centre for Medium-Range Weather Forecasts model that is matched to each cloud object are used to further understand some of the findings in this study.
Wong, Takmeng; Wielicki, Bruce A.; Lee, Robert B.; Smith, G. Louis; Bush, Kathryn A.; Willis, Joshua K.Wong, T., B. A. Wielicki, R. B. Lee, G. L. Smith, K. A. Bush, J. K. Willis, 2006: Reexamination of the Observed Decadal Variability of the Earth Radiation Budget Using Altitude-Corrected ERBE/ERBS Nonscanner WFOV Data. J. Climate, 19(16), 4028-4040. doi: 10.1175/JCLI3838.1. Abstract This paper gives an update on the observed decadal variability of the earth radiation budget (ERB) using the latest altitude-corrected Earth Radiation Budget Experiment (ERBE)/Earth Radiation Budget Satellite (ERBS) Nonscanner Wide Field of View (WFOV) instrument Edition3 dataset. The effects of the altitude correction are to modify the original reported decadal changes in tropical mean (20°N to 20°S) longwave (LW), shortwave (SW), and net radiation between the 1980s and the 1990s from 3.1, −2.4, and −0.7 to 1.6, −3.0, and 1.4 W m−2, respectively. In addition, a small SW instrument drift over the 15-yr period was discovered during the validation of the WFOV Edition3 dataset. A correction was developed and applied to the Edition3 dataset at the data user level to produce the WFOV Edition3_Rev1 dataset. With this final correction, the ERBS Nonscanner-observed decadal changes in tropical mean LW, SW, and net radiation between the 1980s and the 1990s now stand at 0.7, −2.1, and 1.4 W m−2, respectively, which are similar to the observed decadal changes in the High-Resolution Infrared Radiometer Sounder (HIRS) Pathfinder OLR and the International Satellite Cloud Climatology Project (ISCCP) version FD record but disagree with the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder ERB record. Furthermore, the observed interannual variability of near-global ERBS WFOV Edition3_Rev1 net radiation is found to be remarkably consistent with the latest ocean heat storage record for the overlapping time period of 1993 to 1999. Both datasets show variations of roughly 1.5 W m−2 in planetary net heat balance during the 1990s.
Hansen, J., M. Sato, R. Ruedy, L. Nazarenko, A. Lacis, G.A. Schmidt, G. Russell, I. Aleinov, M. Bauer, S. Bauer, N. Bell, B. Cairns, V. Canuto, M. Chandler, Y. Cheng, A. Del Genio, G. Faluvegi, E. Fleming, A. Friend, T. Hall, C. Jackman, M. Kelley, N. Kiang, D. Koch, J. Lean, J. Lerner, K. Lo, S. Menon, R. Miller, P. Minnis, T. Novakov, V. Oinas, Ja. Perlwitz, Ju. Perlwitz, D. Rind, D. Romanou, D. Shindell, P. Stone, S. Sun, N. Tausnev, D. Thresher, B. Wielicki, T. Wong, M. Yao, and S. ZhangHansen, J., M. Sato, R. Ruedy, L. Nazarenko, A. Lacis, G.A. Schmidt, G. Russell, I. Aleinov, M. Bauer, S. Bauer, N. Bell, B. Cairns, V. Canuto, M. Chandler, Y. Cheng, A. Del Genio, G. Faluvegi, E. Fleming, A. Friend, T. Hall, C. Jackman, M. Kelley, N. Kiang, D. Koch, J. Lean, J. Lerner, K. Lo, S. Menon, R. Miller, P. Minnis, T. Novakov, V. Oinas, Ja. Perlwitz, Ju. Perlwitz, D. Rind, D. Romanou, D. Shindell, P. Stone, S. Sun, N. Tausnev, D. Thresher, B. Wielicki, T. Wong, M. Yao, and S. Zhang, 2005: Efficacy of Climate Forcings. Journal of Geophysical Research, 110, D18104. doi: 10.1029/2005JD005776.
Hansen, J.; Sato, M.; Ruedy, R.; Nazarenko, L.; Lacis, A.; Schmidt, G. A.; Russell, G.; Aleinov, I.; Bauer, M.; Bauer, S.; Bell, N.; Cairns, B.; Canuto, V.; Chandler, M.; Cheng, Y.; Del Genio, A.; Faluvegi, G.; Fleming, E.; Friend, A.; Hall, T.; Jackman, C.; Kelley, M.; Kiang, N.; Koch, D.; Lean, J.; Lerner, J.; Lo, K.; Menon, S.; Miller, R.; Minnis, P.; Novakov, T.; Oinas, V.; Perlwitz, Ja.; Perlwitz, Ju.; Rind, D.; Romanou, A.; Shindell, D.; Stone, P.; Sun, S.; Tausnev, N.; Thresher, D.; Wielicki, B.; Wong, T.; Yao, M.; Zhang, S.Hansen, J., M. Sato, R. Ruedy, L. Nazarenko, A. Lacis, G. A. Schmidt, G. Russell, I. Aleinov, M. Bauer, S. Bauer, N. Bell, B. Cairns, V. Canuto, M. Chandler, Y. Cheng, A. Del Genio, G. Faluvegi, E. Fleming, A. Friend, T. Hall, C. Jackman, M. Kelley, N. Kiang, D. Koch, J. Lean, J. Lerner, K. Lo, S. Menon, R. Miller, P. Minnis, T. Novakov, V. Oinas, J. Perlwitz, J. Perlwitz, D. Rind, A. Romanou, D. Shindell, P. Stone, S. Sun, N. Tausnev, D. Thresher, B. Wielicki, T. Wong, M. Yao, S. Zhang, 2005: Efficacy of climate forcings. Journal of Geophysical Research: Atmospheres, 110(D18), D18104. doi: 10.1029/2005JD005776. We use a global climate model to compare the effectiveness of many climate forcing agents for producing climate change. We find a substantial range in the “efficacy” of different forcings, where the efficacy is the global temperature response per unit forcing relative to the response to CO2 forcing. Anthropogenic CH4 has efficacy ∼110%, which increases to ∼145% when its indirect effects on stratospheric H2O and tropospheric O3 are included, yielding an effective climate forcing of ∼0.8 W/m2 for the period 1750–2000 and making CH4 the largest anthropogenic climate forcing other than CO2. Black carbon (BC) aerosols from biomass burning have a calculated efficacy ∼58%, while fossil fuel BC has an efficacy ∼78%. Accounting for forcing efficacies and for indirect effects via snow albedo and cloud changes, we find that fossil fuel soot, defined as BC + OC (organic carbon), has a net positive forcing while biomass burning BC + OC has a negative forcing. We show that replacement of the traditional instantaneous and adjusted forcings, Fi and Fa, with an easily computed alternative, Fs, yields a better predictor of climate change, i.e., its efficacies are closer to unity. Fs is inferred from flux and temperature changes in a fixed-ocean model run. There is remarkable congruence in the spatial distribution of climate change, normalized to the same forcing Fs, for most climate forcing agents, suggesting that the global forcing has more relevance to regional climate change than may have been anticipated. Increasing greenhouse gases intensify the Hadley circulation in our model, increasing rainfall in the Intertropical Convergence Zone (ITCZ), Eastern United States, and East Asia, while intensifying dry conditions in the subtropics including the Southwest United States, the Mediterranean region, the Middle East, and an expanding Sahel. These features survive in model simulations that use all estimated forcings for the period 1880–2000. Responses to localized forcings, such as land use change and heavy regional concentrations of BC aerosols, include more specific regional characteristics. We suggest that anthropogenic tropospheric O3 and the BC snow albedo effect contribute substantially to rapid warming and sea ice loss in the Arctic. As a complement to a priori forcings, such as Fi, Fa, and Fs, we tabulate the a posteriori effective forcing, Fe, which is the product of the forcing and its efficacy. Fe requires calculation of the climate response and introduces greater model dependence, but once it is calculated for a given amount of a forcing agent it provides a good prediction of the response to other forcing amounts. 1620 Climate dynamics; 1616 Climate variability; 1637 Regional climate change; climate models; 1622 Earth system modeling; climate forcings; greenhouse gases
Lin, Bing; Wong, Takmeng; Wielicki, Bruce A.; Hu, YongxiangLin, B., T. Wong, B. A. Wielicki, Y. Hu, 2005: Comments on "Examination of the decadal tropical mean ERBS nonscanner radiation data for the iris hypothesis" - Reply. J. Climate, 18(12), 2128-2131. doi: 10.1175/JCLI3393.1.
Wielicki, Bruce A.; Wong, Takmeng; Loeb, Norman; Minnis, Patrick; Priestley, Kory; Kandel, RobertWielicki, B. A., T. Wong, N. Loeb, P. Minnis, K. Priestley, R. Kandel, 2005: Changes in Earth's Albedo Measured by Satellite. Science, 308(5723), 825-825. doi: 10.1126/science.1106484. NASA global satellite data provide observations of Earth's albedo, i.e., the fraction of incident solar radiation that is reflected back to space. The satellite data show that the last four years are within natural variability and fail to confirm the 6% relative increase in albedo inferred from observations of earthshine from the moon. Longer global satellite records will be required to discern climate trends in Earth's albedo.
Xu, Kuan-Man; Wong, Takmeng; Wielicki, Bruce A.; Parker, Lindsay; Eitzen, Zachary A.Xu, K., T. Wong, B. A. Wielicki, L. Parker, Z. A. Eitzen, 2005: Statistical Analyses of Satellite Cloud Object Data from CERES. Part I: Methodology and Preliminary Results of the 1998 El Niño/2000 La Niña. J. Climate, 18(13), 2497-2514. doi: 10.1175/JCLI3418.1. Abstract This study presents an objective classification methodology that uses Earth Observing System (EOS) satellite data to classify distinct “cloud objects” defined by cloud-system types, sizes, geographic locations, and matched large-scale environments. This analysis method identifies a cloud object as a contiguous region of the earth with a single dominant cloud-system type. It determines the shape and size of the cloud object from the satellite data and the cloud-system selection criteria. The statistical properties of the identified cloud objects are analyzed in terms of probability density functions (PDFs) based upon the Clouds and the Earth’s Radiant Energy System (CERES) Single Satellite Footprint (SSF) data. Four distinct types of oceanic cloud objects—tropical deep convection, boundary layer cumulus, transition stratocumulus, and solid stratus—are initially identified from the CERES data collected from the Tropical Rainfall Measuring Mission (TRMM) satellite for this study. Preliminary results are presented from the analysis of the grand-mean PDFs of these four distinct types of cloud objects associated with the strong 1997/98 El Niño in March 1998 and the very weak 2000 La Niña in March 2000. A majority of the CERES footprint statistical characteristics of observed tropical deep convection are similar between the two periods in spite of the climatological contrast. There are, however, statistically significant differences in some cloud macrophysical properties such as the cloud-top height and cloud-top pressure and moderately significant differences in outgoing longwave radiation (OLR), cloud-top temperature, and ice diameter. The footprint statistical characteristics of the three observed boundary layer cloud-system types are distinctly different from one another in all cloud microphysical, macrophysical, optical properties, and radiative fluxes. The differences between the two periods are not significant for most cloud microphysical and optical properties and the top-of-the-atmosphere albedo, but are statistically significant for some cloud macrophysical properties and OLR. These characteristics of the grand-mean PDFs of cloud microphysical, macrophysical, and optical properties and radiative fluxes can be usefully compared with cloud model simulations. Furthermore, the proportion of different boundary layer cloud types is changed between the two periods in spite of small differences in their grand-mean statistical properties. An increase of the stratus population and a decrease of the cumulus population are evident in the El Niño period compared to the very weak La Niña period. The number of the largest tropical convective cloud objects is larger during the El Niño period, but the total number of tropical convective cloud objects is approximately the same in the two periods.
Lin, Bing; Wong, Takmeng; Wielicki, Bruce A.; Hu, YongxiangLin, B., T. Wong, B. A. Wielicki, Y. Hu, 2004: Examination of the Decadal Tropical Mean ERBS Nonscanner Radiation Data for the Iris Hypothesis. J. Climate, 17(6), 1239-1246. doi: 10.1175/1520-0442(2004)017<1239:EOTDTM>2.0.CO;2. AbstractRecent studies of the Earth Radiation Budget Satellite (ERBS) nonscanner radiation data indicate decadal changes in tropical cloudiness and unexpected radiative anomalies between the 1980s and 1990s. In this study, the ERBS decadal observations are compared with the predictions of the Iris hypothesis using 3.5-box model. To further understand the predictions, the tropical radiative properties observed from recent Clouds and the Earth's Radiant Energy System (CERES) radiation budget experiment [the NASA Langley Research Center (LaRC) parameters] are used to replace the modeled values in the Iris hypothesis. The predicted variations of the radiation fields strongly depend on the relationship (−22% K−1) of tropical high cloud and sea surface temperature (SST) assumed by the Iris hypothesis.On the decadal time scale, the predicted tropical mean radiative flux anomalies are generally significantly different from those of the ERBS measurements, suggesting that the decadal ERBS nonscanner radiative energy budget measurements do not support the strong negative feedback of the Iris effect. Poor agreements between the satellite data and model predictions even when the tropical radiative properties from CERES observations (LaRC parameters) are used imply that besides the Iris-modeled tropical radiative properties, the unrealistic variations of tropical high cloud generated from the detrainment of deep convection with SST assumed by the Iris hypothesis are likely to be another major factor for causing the deviation between the predictions and observations.
Lin, B., T. Wong, B. A. Wielicki, Y. HuLin, B., T. Wong, B. A. Wielicki, Y. Hu, 2003: The decadal tropical mean radiation data and the Iris hypothesis. 2003 IEEE International Geoscience and Remote Sensing Symposium, 5(3211-3212). doi: 10.1109/IGARSS.2003.1294732.
Wang, Pi-Huan; Minnis, Patrick; Wielicki, Bruce A.; Wong, Takmeng; Cess, Robert D.; Zhang, Minghua; Vann, Lelia B.; Kent, Geoffrey S.Wang, P., P. Minnis, B. A. Wielicki, T. Wong, R. D. Cess, M. Zhang, L. B. Vann, G. S. Kent, 2003: Characteristics of the 1997/1998 El Niño cloud distributions from SAGE II observations. Journal of Geophysical Research: Atmospheres, 108(D1), 4009. doi: 10.1029/2002JD002501. The present study examines the characteristics of cloud distributions with emphasis on cloud longwave radiative forcing (CLRF) during the peak of the 1997/1998 El Niño in relation to climatological conditions, based on measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The observed distinct cloud occurrence and CLRF during this unusual 1997/1998 El Niño constitutes a unique data set for validating and improving cloud-radiation-climate interactions in general circulation and climate models. Using the solar occultation technique, the SAGE II satellite instrument is capable of providing measurements with a 1-km vertical resolution facilitating the analysis with sufficient vertical as well as near global scale (70°S–70°N) details. The present study indicates (1) above normal high-altitude opaque cloud occurrence over the eastern tropical Pacific and an opposite situation over the Pacific warm pool, leading to a distribution of the cumulative opaque cloud anomalies above 3 km generally consistent with the pattern of observed tropical sea surface temperature and precipitation anomalies; (2) a similar behavior in the subvisual cloud distributions near the tropical tropopause; (3) a zonally averaged cloud distribution that is characterized by reduced opaque clouds at low latitudes, except in the southern tropics below 10 km, and by enhanced opaque clouds at high latitudes, along with increased subvisual clouds in the southern tropics and decreased subvisual clouds in the northern subtropics in the upper troposphere; and (4) a geographic distribution of model-calculated CLRF anomalies that resembles closely that inferred from the Earth Radiation Budget Experiment and the Clouds and the Earth's Radiant Energy System. A discussion on the influence of the El Niño on large-scale mean tropospheric circulations is also provided. clouds; Remote sensing; 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 0320 Cloud physics and chemistry; 3319 Meteorology and Atmospheric Dynamics: General circulation; 3309 Meteorology and Atmospheric Dynamics: Climatology; climate; 1630 Impacts of global change; El Niño
Trenberth, K. E., B. A. Wielicki, A. D. Del Genio, T. Wong, J. Chen, B. E. Carlson, R. P. Allan, F. Robertson, H. Jacobowitz, A. Slingo, D. Randall, J. T. Kiehl, B. J. Soden, C. T. Gordon, A. J. Miller, S.-K. Yang, and J. SusskindTrenberth, K. E., B. A. Wielicki, A. D. Del Genio, T. Wong, J. Chen, B. E. Carlson, R. P. Allan, F. Robertson, H. Jacobowitz, A. Slingo, D. Randall, J. T. Kiehl, B. J. Soden, C. T. Gordon, A. J. Miller, S.-K. Yang, and J. Susskind, 2002: Technical Comments: Changes in Tropical Clouds and Radiation.. Science, 296, 2095a. doi: 10.1126/science.296.5576.2095a.
Wang, Pi-Huan; Minnis, Patrick; Wielicki, Bruce A.; Wong, Takmeng; Vann, Lelia B.Wang, P., P. Minnis, B. A. Wielicki, T. Wong, L. B. Vann, 2002: Satellite observations of long-term changes in tropical cloud and outgoing longwave radiation from 1985 to 1998. Geophysical Research Letters, 29(10), 37-1. doi: 10.1029/2001GL014264. Cloud vertical distributions and radiation data from satellites taken between 1985 and 1998 were analyzed to determine the impact of clouds on outgoing longwave radiation (OLR) in the Tropics. Clouds with a 1-μm optical depth greater than 0.025 above 12 km decreased, while those below 12 km increased. The OLR mean and decadal trend were 254 Wm−2 and 3.9 Wm−2/decade, respectively. The mean cloud and OLR results were used to derive a value of 0.36 for the tropical mean cloud longwave effective emissivity. Changes in cloud vertical distributions account for 40% of the OLR trend. A change in cloud effective emissivity of −0.026/decade could account for the remainder of the OLR changes. These changes suggest reduced mean cloud opacity, a drier troposphere, and a strengthened large-scale circulation in the Tropics during the period. 1640 Remote sensing; 0320 Cloud physics and chemistry; 3319 Meteorology and Atmospheric Dynamics: General circulation; 3374 Meteorology and Atmospheric Dynamics: Tropical meteorology
Wielicki, BA; Del Genio, AD; Wong, TM; Chen, JY; Carlson, BE; Allan, RP; Robertson, F; Jacobowitz, H; Slingo, A; Randall, DA; Kiehl, JT; Soden, BJ; Gordon, CT; Miller, AJ; Yang, SK; Susskind, JWielicki, B., A. Del Genio, T. Wong, J. Chen, B. Carlson, R. Allan, F. Robertson, H. Jacobowitz, A. Slingo, D. Randall, J. Kiehl, B. Soden, C. Gordon, A. Miller, S. Yang, J. Susskind, 2002: Changes in tropical clouds and radiation - Response. SCIENCE, 296(5576). doi: 10.1126/science.296.5576.2095a.
Wielicki, Bruce A.; Wong, Takmeng; Allan, Richard P.; Slingo, Anthony; Kiehl, Jeffrey T.; Soden, Brian J.; Gordon, C. T.; Miller, Alvin J.; Yang, Shi-Keng; Randall, David A.; Robertson, Franklin; Susskind, Joel; Jacobowitz, HerbertWielicki, B. A., T. Wong, R. P. Allan, A. Slingo, J. T. Kiehl, B. J. Soden, C. T. Gordon, A. J. Miller, S. Yang, D. A. Randall, F. Robertson, J. Susskind, H. Jacobowitz, 2002: Evidence for Large Decadal Variability in the Tropical Mean Radiative Energy Budget. Science, 295(5556), 841-844. doi: 10.1126/science.1065837. It is widely assumed that variations in Earth's radiative energy budget at large time and space scales are small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. Results indicate that the radiation budget changes are caused by changes in tropical mean cloudiness. The results of several current climate model simulations fail to predict this large observed variation in tropical energy budget. The missing variability in the models highlights the critical need to improve cloud modeling in the tropics so that prediction of tropical climate on interannual and decadal time scales can be improved.
Wang, P.-H., B. Wielicki, P. Minnis, T. WongWang, P.-H., B. Wielicki, P. Minnis, T. Wong, 2001: An Estimation of SAGE II Cloud Outgoing Longwave Radiative Forcing Between 1985 And 1998: Preliminary Results [in "IRS 2000: Current Problems in Atmospheric Radiation: Proceedings of the International Radiation Symposium, St. Petersberg, Russia, 24-29 July 2000, St. Petersburg, Russia"]. W. L. Smith and Y. M. Timofeyev eds., A. Deepak Publishing, 741-744.
Hu, Y., B. Wielicki, B. Lin, G. Gibson, S. Tsay, K. Stamnes, and T. WongHu, Y., B. Wielicki, B. Lin, G. Gibson, S. Tsay, K. Stamnes, and T. Wong, 2000: Delta-fit: A Fast and Accurate Treatment of Particle Scattering Phase Function with Weighted SVD Least Square Fitting. Journal of Quantitative Spectroscopy and Radiative Transfer, 65(681-690). doi: 10.1016/S0022-4073(99)00147-8.
Wong, Takmeng; Young, David F.; Haeffelin, Martial; Weckmann, StephanieWong, T., D. F. Young, M. Haeffelin, S. Weckmann, 2000: Validation of the CERES/TRMM ERBE-Like Monthly Mean Clear-Sky Longwave Dataset and the Effects of the 1998 ENSO Event. J. Climate, 13(24), 4256-4267. doi: 10.1175/1520-0442(2000)013<4256:VOTCTE>2.0.CO;2. Abstract The Clouds and the Earth’s Radiant Energy System (CERES) is a new National Aeronautics and Space Administration space-borne measurement project for monitoring the radiation environment of the earth–atmosphere system. The first CERES instrument was launched into space on board the Tropical Rainfall Measuring Mission (TRMM) satellite on 27 November 1997. The purpose of this paper is 1) to describe the initial validation of the new CERES/TRMM Earth Radiation Budget Experiment (ERBE)–like monthly mean clear-sky longwave (CLW) dataset and 2) to demonstrate the scientific benefit of this new dataset through a data application study on the 1998 El Niño–Southern Oscillation (ENSO) episode. The initial validation of the CERES CLW data is carried out based on comparisons with both historical ERBE observations and radiative transfer simulations. While the observed CERES CLWs are initially larger than the historical ERBE record during the first part of the 1998 ENSO event, these differences are diminished by the end of the ENSO event in July 1998. These unique ENSO-related CLW radiation signatures are captured well by the radiative transfer model simulations. These results demonstrate that the new CERES CLW fluxes are theoretically consistent with the underlying physics of the atmosphere. A CERES data application study is performed to examine the relationship between the CERES CLW anomaly and changes in sea surface temperature (SST) and atmospheric column precipitable water content (PWC) during the January 1998 ENSO event. While the changes in the SST pattern are basically uncorrelated with changes in the CLW field, a negative correlation is found between the PWC anomaly and the changes in the CLW radiation field. These observed features point to 1) the significant role of the water vapor field in modulating the tropical outgoing CLW radiation field during the 1998 ENSO event and 2) the important effects of water vapor absorption in decoupling the top of the atmosphere tropical outgoing CLW radiation from the surface upward CLW field.
Wielicki, B.A.; Barkstrom, B.R.; Baum, B.A.; Charlock, T.P.; Green, R.N.; Kratz, D.P.; Lee, R.B.; Minnis, P.; Smith, G.L.; Wong, Takmeng; Young, D.F.; Cess, R.D.; Coakley, J.A.; Crommelynck, D.A.H.; Donner, L.; Kandel, R.; King, M.D.; Miller, A.J.; Ramanathan, V.; Randall, D.A.; Stowe, L.L.; Welch, R.M.Wielicki, B., B. Barkstrom, B. Baum, T. Charlock, R. Green, D. Kratz, R. Lee, P. Minnis, G. Smith, T. Wong, D. Young, R. Cess, J. Coakley, D. Crommelynck, L. Donner, R. Kandel, M. King, A. Miller, V. Ramanathan, D. Randall, L. Stowe, R. Welch, 1998: Clouds and the Earth's Radiant Energy System (CERES): algorithm overview. IEEE Transactions on Geoscience and Remote Sensing, 36(4), 1127-1141. doi: 10.1109/36.701020. The Clouds and the Earth's Radiant Energy System (CERES) is part of NASA's Earth Observing System (EOS), CERES objectives include the following. (1) For climate change analysis, provide a continuation of the Earth Radiation Budget Experiment (ERBE) record of radiative fluxes at the top-of-the-atmosphere (TOA), analyzed using the same techniques as the existing ERBE data. (2) Double the accuracy of estimates of radiative fluxes at TOA and the Earth's surface. (3) Provide the first long-term global estimates of the radiative fluxes within the Earth's atmosphere. (4) Provide cloud property estimates collocated in space and time that are consistent with the radiative fluxes from surface to TOA. In order to accomplish these goals, CERES uses data from a combination of spaceborne instruments: CERES scanners, which are an improved version of the ERBE broadband radiometers, and collocated cloud spectral imager data on the same spacecraft. The CERES cloud and radiative flux data products should prove extremely useful in advancing the understanding of cloud-radiation interactions, particularly cloud feedback effects on the Earth's radiation balance. For this reason, the CERES data should be fundamental to the ability to understand, detect, and predict global climate change. CERES results should also be very useful for studying regional climate changes associated with deforestation, desertification, anthropogenic aerosols, and ENSO events. This overview summarizes the Release 3 version of the planned CERES data products and data analysis algorithms. These algorithms are a prototype for the system that will produce the scientific data required for studying the role of clouds and radiation in the Earth's climate system atmosphere; clouds; geophysical signal processing; Remote sensing; atmospheric radiation; aerosols; algorithm; atmospheric techniques; CERES; Change detection algorithms; cloud; Clouds and the Earth's Radiant Energy System; Data analysis; data processing; Earth Observing System; EOS; Feedback; infrared radiation; Instruments; measurement technique; Meteorology; radiative flux; radiometers; satellite remote sensing; Space vehicles; Terrestrial atmosphere; thermal radiation
Young, D. F.; Minnis, P.; Doelling, D. R.; Gibson, G. G.; Wong, T.Young, D. F., P. Minnis, D. R. Doelling, G. G. Gibson, T. Wong, 1998: Temporal Interpolation Methods for the Clouds and the Earth’s Radiant Energy System (CERES) Experiment. Journal of Applied Meteorology, 37(6), 572-590. doi: 10.1175/1520-0450(1998)037<0572:TIMFTC>2.0.CO;2. Abstract The Clouds and the Earth’s Radiant Energy System (CERES) is a NASA multisatellite measurement program for monitoring the radiation environment of the earth–atmosphere system. The CERES instrument was flown on the Tropical Rainfall Measuring Mission satellite in late 1997, and will be flown on the Earth Observing System morning satellite in 1998 and afternoon satellite in 2000. To minimize temporal sampling errors associated with satellite measurements, two methods have been developed for temporally interpolating the CERES earth radiation budget measurements to compute averages of top-of-the-atmosphere shortwave and longwave flux. The first method is based on techniques developed from the Earth Radiation Budget Experiment (ERBE) and provides radiation data that are consistent with the ERBE processing. The second method is a newly developed technique for use in the CERES data processing. This technique incorporates high temporal resolution data from geostationary satellites to improve modeling of diurnal variations of radiation due to changing cloud conditions during the day. The performance of these two temporal interpolation methods is evaluated using a simulated dataset. Simulation studies show that the introduction of geostationary data into the temporal interpolation process significantly improves the accuracy of hourly and daily radiative products. Interpolation errors for instantaneous flux estimates are reduced by up to 68% for longwave flux and 80% for shortwave flux.
Wong, T., P. Minnis, and C. H. WhitlockWong, T., P. Minnis, and C. H. Whitlock, 1997: Anisotropy of surface-emitted radiation [in "IRS '96: Current Problems in Atmospheric Radiation. Proceedings of the International Radiation Symposium 1996, Fairbanks, Alaska, 19-24 August 1996"]. W. L. Smith and K. Stamnes eds., A. Deepak Publishing, 457-460.
Wong, Takmeng; Harrison, Edwin F.; Gibson, Gary G.; Denn, Frederick M.Wong, T., E. F. Harrison, G. G. Gibson, F. M. Denn, 1997: On the Determination of the Optimal Scan Mode Sequence for the TRMM CERES Instrument. J. Atmos. Oceanic Technol., 14(5), 1230-1236. doi: 10.1175/1520-0426(1997)014<1230:OTDOTO>2.0.CO;2. Abstract Clouds and the Earth’s Radiant Energy System (CERES) is a NASA spaceborne measurement program for monitoring the radiation environment of the earth–atmosphere system. The first CERES instrument is scheduled to be launched on board the Tropical Rainfall Measuring Mission (TRMM) satellite in late 1997. In addition to gathering traditional cross-track fixed azimuth measurements for calculating monthly mean radiation fields, this single CERES scanner instrument will also be required to collect angular radiance data using a rotating azimuth configuration for developing new angular dependence models (ADMs). Since the TRMM single CERES instrument can only be run in either one of these two configurations at any one time, it will need to be operated in a cyclical pattern between these two scan modes to achieve the intended measurement goals. To minimize the errors in the derived monthly mean radiation field due to missing cross-track scanner measurements during this satellite mission, determination of the optimal scan mode sequence for the TRMM single CERES instrument is carried out. The Earth Radiation Budget Experiment S-4 daily mean cross-track scanner data product for April and July 1985 and January 1986 is used with a simple temporal sampling scheme to produce simulated daily mean cross-track scanner measurements under different TRMM CERES operational scan mode sequences. Error analysis is performed on the monthly mean radiation fields derived from these simulated datasets. It is found that the best monthly mean result occurred when the cross-track scanner is operated on a “2 days on and 1 day off” mode. This scan mode sequence will effectively allow for 2 consecutive days of cross-track scanner data and 1 day of angular radiance measurement for each 3-day period. The root-mean-square errors for the monthly mean all-sky (clear sky) longwave and shortwave radiation field, due to missing cross-track scanner measurements for this particular case, are expected to be less than 2.5 (0.5) and 5.0 (1.5) W m−2, respectively.
Evans, K. F., J. Turk, T. Wong, and G. L. StephensEvans, K. F., J. Turk, T. Wong, and G. L. Stephens, 1995: A Bayesian approach to microwave precipitation profile retrieval. Journal of Applied Meteorology, 34(260-279). doi: 10.1175/1520-0450-34.1.260.
Wong, T. and G. L. StephensWong, T. and G. L. Stephens, 1994: On the radiative processes associated with the tropical mesoscale convective systems. Atmospheric Science Paper, Colorado State University, Fort Collins, Colorado, 547(235pp).
Wong, T., G. L. Stephens, P. W. Stackhouse, and F. P. J. ValeroWong, T., G. L. Stephens, P. W. Stackhouse, and F. P. J. Valero, 1993: The radiative budgets of a tropical mesoscale convective system during the EMEX-STEP-AMEX experiment. 2. Model Results. Journal of Geophysical Research, 98, No. D5(8695-8711). doi: 10.1029/92JD02516.
Wong, T., G. L. Stephens, P. W. Stackhouse, and F. P. J. ValeroWong, T., G. L. Stephens, P. W. Stackhouse, and F. P. J. Valero, 1993: The radiative budgets of a tropical mesoscale convective system during the EMEX-STEP-AMEX experiment. 1. Observations. Journal of Geophysical Research, 98, No. D5(8683-8693). doi: 10.1029/92JD02515.
Stephens, G. L. and T. WongStephens, G. L. and T. Wong, 1987: The effects of cloud and climate as deduced from simple model [in "Atmospheric Radiation: Progress and Prospects, Proceedings of the Beijing International Radiation Symposium, Beijing, China, August 26–30, 1986"]. KN. Liou and Z. Xiuji eds., American Meteorological Society, Boston, MA, 418-425. doi: 10.1007/978-1-935704-18-8_62.
Wong, T. and G. L. StephensWong, T. and G. L. Stephens, 1987: Equilibrium climate modeling with an one dimensional coupled atmosphere-ocean model. Atmospheric Science Paper, Colorado State University, Fort Collins, Colorado, 424(123pp).
