Kratz, David P.; Gupta, Shashi K.; Wilber, Anne C.; Sothcott, Victor E.Kratz, D. P., S. K. Gupta, A. C. Wilber, V. E. Sothcott, 2020: Validation of the CERES Edition-4A Surface-Only Flux Algorithms. J. Appl. Meteor. Climatol., 59(2), 281-295. doi: 10.1175/JAMC-D-19-0068.1. Surface radiative fluxes have been derived with the objective of supplementing top-of-atmosphere (TOA) radiative fluxes being measured under NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project. This has been accomplished by using combinations of CERES TOA measurements, parameterized radiative transfer algorithms, and high-quality meteorological datasets available from reanalysis projects. Current CERES footprint-level products include surface fluxes derived from two shortwave (SW) and three longwave (LW) algorithms designated as SW models A and B and LW models A, B, and C. The SW and LW models A work for clear conditions only; the other models work for both clear and cloudy conditions. The current CERES Edition-4A computed surface fluxes from all models are validated against ground-based flux measurements from high-quality surface networks like the Baseline Surface Radiation Network and NOAA’s Surface Radiation Budget Network (SURFRAD). Validation results as systematic and random errors are provided for all models, separately for five different surface types and combined for all surface types as tables and scatterplots. Validation of surface fluxes is now a part of CERES processing and is used to continually improve the above algorithms. Since both models B work for clear and cloudy conditions alike and meet the accuracy requirement, their results are considered to be the most reliable and most likely to be retained for future work. Both models A have limited use given that they work for clear skies only. Models B will continue to undergo further improvement as more validation results become available.
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.
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.
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.
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.
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.
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.
Kratz, David P.; Stackhouse, Paul W.; Gupta, Shashi K.; Wilber, Anne C.; Sawaengphokhai, Parnchai; McGarragh, Greg R.Kratz, D. P., P. W. Stackhouse, S. K. Gupta, A. C. Wilber, P. Sawaengphokhai, G. R. McGarragh, 2014: The Fast Longwave and Shortwave Flux (FLASHFlux) Data Product: Single-Scanner Footprint Fluxes. J. Appl. Meteor. Climatol., 53(4), 1059-1079. doi: 10.1175/JAMC-D-13-061.1. AbstractThe Clouds and the Earth’s Radiant Energy Systems (CERES) project utilizes radiometric measurements taken aboard the Terra and Aqua spacecrafts to derive the world-class data products needed for climate research. Achieving the exceptional fidelity of the CERES data products, however, requires a considerable amount of processing to assure quality and to verify accuracy and precision, which results in the CERES data being released more than 6 months after the satellite observations. For most climate studies such delays are of little consequence; however, there are a significant number of near–real time uses for CERES data products. The Fast Longwave and Shortwave Radiative Flux (FLASHFlux) data product was therefore developed to provide a rapid release version of the CERES results, which could be made available to the research and applications communities within 1 week of the satellite observations by exchanging some accuracy for speed. FLASHFlux has both achieved this 1-week processing objective and demonstrated the ability to provide remarkably good agreement when compared with the CERES data products for both the instantaneous single-scanner footprint (SSF) fluxes and the time- and space-averaged (TISA) fluxes. This paper describes the methods used to expedite the production of the FLASHFlux SSF fluxes by utilizing data from the CERES and Moderate Resolution Imaging Spectroradiometer instruments, as well as other meteorological sources. This paper also reports on the validation of the FLASHFlux SSF results against ground-truth measurements and the intercomparison of FLASHFlux and CERES SSF results. A complementary paper will discuss the production and validation of the FLASHFlux TISA fluxes. satellite observations; longwave radiation; Shortwave radiation; Surface observations; Surface fluxes
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.
Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J.; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C.O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jin, Z.; Jennings, D.; Johnson, D. G.; Jucks, K.; Kato, S.; Kirk-Davidoff, D. B.; Knuteson, R.; Kopp, G.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Pilewskie, P.; Ramaswamy, V.; Revercomb, H.; Rice, J.; Roberts, Y.; Roithmayr, C. M.; Rose, F.; Sandford, S.; Shirley, E. L.; Smith, W.L.; Soden, B.; Speth, P. W.; Sun, W.; Taylor, P.C.; Tobin, D.; Xiong, X.Wielicki, B. A., D. F. Young, M. G. Mlynczak, K. J. Thome, S. Leroy, J. Corliss, J. G. Anderson, C. Ao, R. Bantges, F. Best, K. Bowman, H. Brindley, J. J. Butler, W. Collins, J. A. Dykema, D. R. Doelling, D. R. Feldman, N. Fox, X. Huang, R. Holz, Y. Huang, Z. Jin, D. Jennings, D. G. Johnson, K. Jucks, S. Kato, D. B. Kirk-Davidoff, R. Knuteson, G. Kopp, D. P. Kratz, X. Liu, C. Lukashin, A. J. Mannucci, N. Phojanamongkolkij, P. Pilewskie, V. Ramaswamy, H. Revercomb, J. Rice, Y. Roberts, C. M. Roithmayr, F. Rose, S. Sandford, E. L. Shirley, W. Smith, B. Soden, P. W. Speth, W. Sun, P. Taylor, D. Tobin, X. Xiong, 2013: Achieving Climate Change Absolute Accuracy in Orbit. Bull. Amer. Meteor. Soc., 130308154356007. doi: 10.1175/BAMS-D-12-00149.1.
Garnier, Anne; Pelon, Jacques; Dubuisson, Philippe; Faivre, Michaël; Chomette, Olivier; Pascal, Nicolas; Kratz, David P.Garnier, A., J. Pelon, P. Dubuisson, M. Faivre, O. Chomette, N. Pascal, D. P. Kratz, 2012: Retrieval of Cloud Properties Using CALIPSO Imaging Infrared Radiometer. Part I: Effective Emissivity and Optical Depth. J. Appl. Meteor. Climatol., 51(7), 1407-1425. doi: 10.1175/JAMC-D-11-0220.1. AbstractThe paper describes the operational analysis of the Imaging Infrared Radiometer (IIR) data, which have been collected in the framework of the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission for the purpose of retrieving high-altitude (above 7 km) cloud effective emissivity and optical depth that can be used in synergy with the vertically resolved Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) collocated observations. After an IIR scene classification is built under the CALIOP track, the analysis is applied to features detected by CALIOP when found alone in the atmospheric column or when CALIOP identifies an opaque layer underneath. The fast-calculation radiative transfer (FASRAD) model fed by ancillary meteorological and surface data is used to compute the different components involved in the effective emissivity retrievals under the CALIOP track. The track analysis is extended to the IIR swath using homogeneity criteria that are based on radiative equivalence. The effective optical depth at 12.05 μm is shown to be a good proxy for about one-half of the cloud optical depth, allowing direct comparisons with other databases in the visible spectrum. A step-by-step quantitative sensitivity and performance analysis is provided. The method is validated through comparisons of collocated IIR and CALIOP optical depths for elevated single-layered semitransparent cirrus clouds, showing excellent agreement (within 20%) for values ranging from 1 down to 0.05. Uncertainties have been determined from the identified error sources. The optical depth distribution of semitransparent clouds is found to have a nearly exponential shape with a mean value of about 0.5–0.6. infrared radiation; cirrus clouds; satellite observations; Optical properties; Algorithms; Lidars/Lidar observations
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.
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.
Gupta, Shashi K.; Kratz, David P.; Stackhouse, Paul W.; Wilber, Anne C.; Zhang, Taiping; Sothcott, Victor E.Gupta, S. K., D. P. Kratz, P. W. Stackhouse, A. C. Wilber, T. Zhang, V. E. Sothcott, 2010: Improvement of Surface Longwave Flux Algorithms Used in CERES Processing. J. Appl. Meteor. Climatol., 49(7), 1579-1589. doi: 10.1175/2010JAMC2463.1. Abstract An improvement was developed and tested for surface longwave flux algorithms used in the Clouds and the Earth’s Radiant Energy System processing based on lessons learned during the validation of global results of those algorithms. The algorithms involved showed significant overestimation of downward longwave flux for certain regions, especially dry–arid regions during hot times of the day. The primary cause of this overestimation was identified and the algorithms were modified to (i) detect meteorological conditions that would produce an overestimation, and (ii) apply a correction when the overestimation occurred. The application of this correction largely eliminated the positive bias that was observed in earlier validation studies. Comparisons of validation results before and after the application of correction are presented. Fluxes; longwave radiation; Algorithms
Kratz, David P.; Gupta, Shashi K.; Wilber, Anne C.; Sothcott, Victor E.Kratz, D. P., S. K. Gupta, A. C. Wilber, V. E. Sothcott, 2010: Validation of the CERES Edition 2B Surface-Only Flux Algorithms. J. Appl. Meteor. Climatol., 49(1), 164-180. doi: 10.1175/2009JAMC2246.1. Abstract The Clouds and the Earth’s Radiant Energy System (CERES) project uses two shortwave (SW) and two longwave (LW) algorithms to derive surface radiative fluxes on an instantaneous footprint basis from a combination of top-of-atmosphere fluxes, ancillary meteorological data, and retrieved cloud properties. Since the CERES project examines the radiative forcings and feedbacks for Earth’s entire climate system, validation of these models for a wide variety of surface conditions is paramount. The present validation effort focuses upon the ability of these surface-only flux algorithms to produce accurate CERES Edition 2B single scanner footprint data from the Terra and Aqua spacecraft measurements. To facilitate the validation process, high-quality radiometric surface observations have been acquired that were coincident with the CERES-derived surface fluxes. For both SW models, systematic errors range from −20 to −12 W m−2 (from −2.8% to −1.6%) for global clear-sky cases, while for the all-sky SW model, the systematic errors range from 14 to 21 W m−2 (3.2%–4.8%) for global cloudy-sky cases. Larger systematic errors were seen for the individual surface types, and significant random errors where observed, especially for cloudy-sky cases. While the SW models nearly achieved the 20 W m−2 accuracy requirements established for climate research, further improvements are warranted. For the clear-sky LW model, systematic errors were observed to fall within ±5.4 W m−2 (±1.9%) except for the polar case in which systematic errors on the order from −15 to −11 W m−2 (from −13% to −7.2%) occurred. For the all-sky LW model, systematic errors were less than ±9.2 W m−2 (±7.6%) for both the clear-sky and cloudy-sky cases. The random errors were less than 17 W m−2 (6.2%) for clear-sky cases and 28 W m−2 (13%) for cloudy-sky cases, except for the desert cases in which very high surface skin temperatures caused an overestimation in the model-calculated surface fluxes. Overall, however, the LW models met the accuracy requirements for climate research. satellite observations; longwave radiation; Shortwave radiation; Surface fluxes
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.
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.
Kratz, David P.Kratz, D. P., 2008: The sensitivity of radiative transfer calculations to the changes in the HITRAN database from 1982 to 2004. Journal of Quantitative Spectroscopy and Radiative Transfer, 109(6), 1060-1080. doi: 10.1016/j.jqsrt.2007.10.010. Over the last quarter century, improvements in the determination of the spectroscopic characteristics of the infrared-active trace species have enhanced our ability to retrieve quantitative distributions of temperatures, clouds, and abundances for various trace species within the Earth's atmosphere. These improvements have also allowed for refinements in the estimates of climatic effects attributed to changes in the Earth's atmospheric composition. Modeling efforts, however, have frequently experienced significant delays in assimilating improved spectroscopic information. Such is the case for highly parameterized models, where considerable effort is typically required to incorporate any revisions. Thus, a line-by-line radiative transfer model has been used to investigate the magnitude of the effects resulting from modifications to the spectroscopic information. Calculations from this line-by-line model have demonstrated that recent modifications to the HITRAN (High Resolution Transmission) line parameters, the continuum formulation, and the CO2 line-mixing formulation can significantly affect the interpretation of the high spectral resolution radiance and brightness temperature retrievals. For certain moderate-resolution satellite remote sensing channels, modifications to these spectroscopic parameters and formulations have shown the capacity to induce changes in the calculated radiances equivalent to brightness temperature differences of 1–2 K. Model calculations have further shown that modifications of the spectroscopic characteristics tend to have a modest effect on the determination of spectrally integrated radiances, fluxes, and radiative forcing estimates, with the largest differences being of order 1 W m−2 for the total thermal infrared fluxes, and of order 2–3% of the calculated radiative forcing at the tropopause attributed to the combined doubling of CO2, N2O, and CH4. The results from this investigation are intended to function as a guide to differentiate between cases where older parameterizations provide acceptable results, within specified accuracy bounds, and cases where upgrades to the latest spectroscopic database are necessary. Correlated k-distribution; Fluxes; HITRAN database; Infrared; Line parameters; Line-by-line calculation; Radiances; Radiative forcings
Zhou, Yaping; Kratz, David P.; Wilber, Anne C.; Gupta, Shashi K.; Cess, Robert D.Zhou, Y., D. P. Kratz, A. C. Wilber, S. K. Gupta, R. D. Cess, 2007: An improved algorithm for retrieving surface downwelling longwave radiation from satellite measurements. Journal of Geophysical Research: Atmospheres, 112(D15), D15102. doi: 10.1029/2006JD008159. Zhou and Cess (2001) developed an algorithm for retrieving surface downwelling longwave radiation (SDLW) based upon detailed studies using radiative transfer model calculations and surface radiometric measurements. The algorithm links clear sky SDLW with surface upwelling longwave (LW) flux and column precipitable water vapor. For cloudy sky cases, the cloud liquid water path is used as an additional parameter to account for the effects of clouds. Despite the simplicity of the algorithm, it performs very well for most geographical regions except for those regions where the atmospheric conditions near the surface tend to be extremely cold and dry. Systematic errors are also found for scenes that are covered with ice clouds. An improved version of the algorithm prevents the large errors in the SDLW at low water vapor amounts by taking into account that, under such conditions, the SDLW and water vapor amount are nearly linear in their relationship. The new algorithm also utilizes cloud fraction and cloud liquid and ice water paths available from the Cloud and the Earth's Radiant Energy System (CERES) single-scanner footprint (SSF) product to separately compute the clear and cloudy portions of the fluxes. The new algorithm has been validated against surface measurements at 29 stations around the globe for Terra and Aqua satellites. The results show significant improvement over the original version. Preliminary tests also suggest that the new algorithm works quite well for high elevation locations such as Tibet site where current satellite products exhibit large biases. The revised Zhou-Cess algorithm is also slightly better or comparable to more sophisticated algorithms currently implemented in the CERES processing and will be incorporated as one of the CERES empirical surface radiation algorithms. 0360 Radiation: transmission and scattering; 1640 Remote sensing; CERES; 3359 Radiative processes; 3337 Global climate models; 1622 Earth system modeling; empirical surface radiation algorithm; Radiative transfer in atmosphere
Kratz, D. P.; Mlynczak, M. G.; Mertens, C. J.; Brindley, H.; Gordley, L. L.; Martin-Torres, J.; Miskolczi, F. M.; Turner, D. D.Kratz, D. P., M. G. Mlynczak, C. J. Mertens, H. Brindley, L. L. Gordley, J. Martin-Torres, F. M. Miskolczi, D. D. Turner, 2005: An inter-comparison of far-infrared line-by-line radiative transfer models. Journal of Quantitative Spectroscopy & Radiative Transfer, 90(3-4), 323-341. doi: 10.1016/j.jqsrt.2004.04.006. A considerable fraction (>40%) of the outgoing longwave radiation escapes from the Earth's atmosphere-surface system within a region of the spectrum known as the far-infrared (wave-numbers less than 650 cm(-1)). Dominated by the line and continuum spectral features of the pure rotation band of water vapor, the far-infrared has a strong influence upon the radiative balance of the troposphere, and hence upon the climate of the Earth. Despite the importance of the far-infrared contribution, however, very few spectrally resolved observations have been made of the atmosphere for wave-numbers less than 650 cm(-1). The National Aeronautics and Space Administration (NASA), under its Instrument Incubator Program (IIP), is currently developing technology that will enable routine, space-based spectral measurements of the far-infrared. As part of NASA's IIP, the Far-Infrared Spectroscopy of the Troposphere (FIRST) project is developing an instrument that will have the capability of measuring the spectrum over the range from 100 to 1000 cm(-1) at a resolution of 0.6 cm(-1). To properly analyze the data from the FIRST instrument, accurate radiative transfer models will be required. Unlike the mid-infrared, however, no inter-comparison of codes has been performed for the far-infrared. Thus, in parallel with the development of the FIRST instrument, an investigation has been under-taken to inter-compare radiative transfer models for potential use in the analysis of far-infrared measurements. The initial phase of this investigation has focused upon the inter-comparison of six distinct line-by-line models. The results from this study have demonstrated remarkably good agreement among the models, with differences being of order 0.5%, thereby providing a high measure of confidence in our ability to accurately compute spectral radiances in the far-infrared. (C) 2004 Elsevier Ltd. All rights reserved.
Gupta, Shashi K.; Kratz, David P.; Wilber, Anne C.; Nguyen, L. CathyGupta, S. K., D. P. Kratz, A. C. Wilber, L. C. Nguyen, 2004: Validation of Parameterized Algorithms Used to Derive TRMM–CERES Surface Radiative Fluxes. J. Atmos. Oceanic Technol., 21(5), 742-752. doi: 10.1175/1520-0426(2004)021<0742:VOPAUT>2.0.CO;2. AbstractParameterized shortwave and longwave algorithms developed at the Langley Research Center have been used to derive surface radiative fluxes in the processing of the Clouds and the Earth's Radiant Energy System (CERES) data obtained from flight aboard the Tropical Rainfall Measuring Mission (TRMM) satellite. Retrieved fluxes were validated on an instantaneous–footprint basis using coincident surface measurements obtained from the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) central facility, the ARM/SGP network of extended facilities, and a number of surface sites of the Baseline Surface Radiation Network (BSRN) and the Climate Monitoring and Diagnostics Laboratory (CMDL). Validation was carried out separately for clear-sky and all-sky conditions. For the shortwave, systematic errors varied from −12 to 10 W m−2 for clear skies and from −5 to 35 W m−2 for all-sky conditions. Random errors varied from 20 to 40 W m−2 for clear skies but were much larger (45–85 W m−2) for all-sky conditions. For the longwave, systematic errors were comparatively small for both clear-sky and all-sky conditions (0 to −10 W m−2) and random errors were within about 20 W m−2. In general, comparisons with surface data from the ARM/SGP site (especially the central facility) showed the best agreement. Large systematic errors in shortwave comparisons for some sites were related to flaws in the surface measurements. Larger errors in longwave fluxes for some footprints were found to be related to the errors in cloud mask retrievals, mostly during the nighttime. Smaller longwave errors related to potential errors in the operational analysis products used in satellite retrievals were also found. Still, longwave fluxes obtained with the present algorithm nearly meet the accuracy requirements for climate research.
Smith, G. Louis; Wielicki, Bruce A.; Barkstrom, Bruce R.; Lee, Robert B.; Priestley, Kory J.; Charlock, Thomas P.; Minnis, Patrick; Kratz, David P.; Loeb, Norman; Young, David F.Smith, G. L., B. A. Wielicki, B. R. Barkstrom, R. B. Lee, K. J. Priestley, T. P. Charlock, P. Minnis, D. P. Kratz, N. Loeb, D. F. Young, 2004: Clouds and Earth radiant energy system: an overview. Advances in Space Research, 33(7), 1125-1131. doi: 10.1016/S0273-1177(03)00739-7. The Clouds and Earth radiant energy system (CERES) instrument was first flown aboard the TRMM spacecraft whose 35° inclination orbit allowed for the collection of radiation budget data over all local times, i.e. all solar zenith angles for the latitude range. Moreover, this instrument has gathered the only bidirectional radiance data covering all local times. An additional quartet of CERES instruments are now operating in pairs on both the TERRA and AQUA spacecrafts. Thus far, these instruments have collected several years of Earth radiation budget observations and continue to operate. For each of the TERRA and AQUA spacecrafts, one CERES instrument operates in a cross-track scan mode for the purpose of mapping the Earth’s outgoing longwave radiation and reflected solar radiation. The other operates in an azimuthal rotation while scanning also in zenith angle for the purpose of gathering measurements for the angular distribution of radiance from various scene types, to improve the computation of fluxes from radiance measurements. The CERES instruments carry in-flight calibration systems to maintain the measurement accuracy of 1% for measured radiances. In addition to retrieving fluxes at the top of the atmosphere, the CERES program uses data from other instruments aboard the spacecraft to compute the radiation balance at the surface and at levels through the atmosphere. CERES; radiation budget; Aqua; Earth observation system; Terra
Kratz, David P.; Priestley, Kory J.; Green, Richard N.Kratz, D. P., K. J. Priestley, R. N. Green, 2002: Establishing the relationship between the CERES window and total channel measured radiances for conditions involving deep convective clouds at night. Journal of Geophysical Research: Atmospheres, 107(D15), ACL 5-1. doi: 10.1029/2001JD001170. Characterizing the stability of the Clouds and the Earth's Radiant Energy System (CERES) instrument is critical to obtaining accurate measurements of the radiative energy budget of the Earth's atmosphere-surface system. Composed of three broadband radiometers, the CERES instrument measures radiances in the shortwave (>2000 cm−1), infrared window (835–1250 cm−1), and total regions of the spectrum. Such a choice of radiometers does not allow for a straightforward three channel intercomparison of the CERES measurements. We observed, however, the outgoing infrared spectra of high, cold, optically thick clouds were fairly representative of blackbody emission. This observation suggested a potential relationship between the infrared window radiometer and longwave portion of the total radiometer. Using nighttime measurements made by the CERES instrument aboard the Tropical Rainfall Measuring Mission (TRMM) spacecraft during the first eight months of 1998, we were able to determine a highly correlated relationship between the infrared window and total channel radiances for conditions corresponding to high, cold, optically thick clouds. Comparisons were then made between the measurements and reference line-by-line calculations. From these comparisons, a quantified relationship was derived between the total and window channel radiances which could accurately reproduce one set of results from the other. Such a relationship has allowed for the establishment of a three channel intercomparison for the CERES instrument with an accuracy of ∼1% for the case of high, cold, optically thick clouds. An independent relationship based upon the tropical mean is shown to produce results which support the three channel analysis for the deep convective cloud systems. 0360 Radiation: transmission and scattering; 1640 Remote sensing; 0394 Instruments and techniques; 1694 Instruments and techniques; CERES; TRMM; 0325 Evolution of the atmosphere; deep-convective-clouds; infrared-window; radiometer; three-channel-intercomparison
Minnis, Patrick; Nguyen, Louis; Doelling, David R.; Young, David F.; Miller, Walter F.; Kratz, David P.Minnis, P., L. Nguyen, D. R. Doelling, D. F. Young, W. F. Miller, D. P. Kratz, 2002: Rapid Calibration of Operational and Research Meteorological Satellite Imagers. Part I: Evaluation of Research Satellite Visible Channels as References. J. Atmos. Oceanic Technol., 19(9), 1233-1249. doi: 10.1175/1520-0426(2002)019<1233:RCOOAR>2.0.CO;2. Abstract Operational meteorological satellites generally lack reliable onboard calibration systems for solar-imaging channels. Current methods for calibrating these channels and for normalizing similar channels on contemporaneous satellite imagers typically rely on a poorly calibrated reference source. To establish a more reliable reference instrument for calibration normalization, this paper examines the use of research satellite imagers that maintain their solar-channel calibrations by using onboard diffuser systems that rely on the sun as an absolute reference. The Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission (TRMM) satellite and the second Along-Track Scanning Radiometer (ATSR-2) on the second European Remote Sensing Satellite (ERS-2) are correlated with matched data from the eighth Geostationary Operational Environmental Satellite (GOES-8), the fifth Geostationary Meteorological satellite (GMS-5), and with each other to examine trends in the solar channels. VIRS data are also correlated with the Terra satellite's Moderate Resolution Imaging Spectroradiometer (MODIS) provisional data as a preliminary assessment of their relative calibrations. As an additional check on their long-term stability, the VIRS data are compared to the relevant corresponding broadband shortwave radiances of the Clouds and the Earth's Radiant Energy System (CERES) scanners on TRMM. No statistically significant trend in the calibration of the VIRS 0.65- and 1.64-μm channels could be detected from the comparisons with CERES data taken during 1998 and 2000. The VIRS-to-GOES-8 correlations revealed an annual degradation rate for the GOES-8 visible (0.67 μm) channel of ∼7.5% and an initial drop of 16% in the gain from the prelaunch value. The slopes in the GOES-8 visible-channel gain trend lines derived from VIRS data taken after January 1998 and ATSR-2 data taken between October 1995 and December 1999 differed by only 1%–2% indicating that both reference instruments are highly stable. The mean difference of 3%–4.8% between the VIRS–GOES-8 and ATSR-2–GOES-8 gains is attributed to spectral differences between ATSR-2 and VIRS and to possible biases in the ATSR-2 channel-2 calibration. A degradation rate of 1.3% per year found for the GMS-5 visible channel was confirmed by comparisons with earlier calibrations. The MODIS and VIRS calibrations agreed to within −1% to 3%. Some of the differences between VIRS and the provisional MODIS radiances can be explained by spectral differences between the two instruments. The MODIS measures greater reflectance than VIRS for bright scenes. Although both VIRS and ATSR-2 provide temporally stable calibrations, it is recommended that, at least until MODIS calibrations are finalized, VIRS should be used as a reference source for normalizing operational meteorological satellite imagers because of its broader visible filter.
Minnis, Patrick; Nguyen, Louis; Doelling, David R.; Young, David F.; Miller, Walter F.; Kratz, David P.Minnis, P., L. Nguyen, D. R. Doelling, D. F. Young, W. F. Miller, D. P. Kratz, 2002: Rapid Calibration of Operational and Research Meteorological Satellite Imagers. Part II: Comparison of Infrared Channels. J. Atmos. Oceanic Technol., 19(9), 1250-1266. doi: 10.1175/1520-0426(2002)019<1250:RCOOAR>2.0.CO;2. Abstract To establish a more reliable reference instrument for calibration normalization, this paper examines the differences between the various thermal infrared imager channels on a set of research and operational satellites. Mean brightness temperatures from the Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission (TRMM) satellite and the second Along-Track Scanning Radiometer (ATSR-2) on the second European Remote Sensing Satellite (ERS-2) are correlated with matched data from the eighth Geostationary Operational Environmental Satellite (GOES-8), the fifth Geostationary Meteorological Satellite (GMS-5), and with each other. VIRS data are also correlated with the Terra satellite's Moderate Resolution Imaging Spectroradiometer (MODIS) provisional data as a preliminary assessment of their relative calibrations. As an additional check on their long-term stability, the VIRS data are compared to the broadband longwave radiances of the Clouds and the Earth's Radiant Energy System (CERES) scanners on TRMM. No statistically significant trend in the calibration of any of the three (3.7, 10.8, and 12.0 μm) VIRS thermal channels could be detected from the comparisons with CERES data taken during 1998 and 2000 indicating that the VIRS channels can serve as a reliable reference for intercalibrating satellite imagers. However, a small day–night difference in the VIRS thermal channels detected at very low temperatures should be taken into account. In general, most of the channels agreed to within less than ±0.7 K over a temperature range between 200 and 300 K. Some of the smaller differences can be explained by spectral differences in the channel response functions. A few larger differences were found at 200 K for some of the channels suggesting some basic calibration differences for lower temperatures. A nearly 3-K bias in the ATSR-2 11-μm channel relative to VIRS and GOES-8 was found at the cold end of the temperature range. The intercalibrations described here are being continued on a routine basis.
Nasiri, Shaima L.; Baum, Bryan A.; Heymsfield, Andrew J.; Yang, Ping; Poellot, Michael R.; Kratz, David P.; Hu, YongxiangNasiri, S. L., B. A. Baum, A. J. Heymsfield, P. Yang, M. R. Poellot, D. P. Kratz, Y. Hu, 2002: The Development of Midlatitude Cirrus Models for MODIS Using FIRE-I, FIRE-II, and ARM In Situ Data. Journal of Applied Meteorology, 41(3), 197-217. doi: 10.1175/1520-0450(2002)041<0197:TDOMCM>2.0.CO;2. Abstract Detailed in situ data from cirrus clouds have been collected during dedicated field campaigns, but the use of the size and habit distribution data has been lagging in the development of more realistic cirrus scattering models. In this study, the authors examine the use of in situ cirrus data collected during three field campaigns to develop more realistic midlatitude cirrus microphysical models. Data are used from the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE)-I (1986) and FIRE-II (1991) campaigns and from a recent Atmospheric Radiation Measurement (ARM) Program campaign held in March–April of 2000. The microphysical models are based on measured vertical distributions of both particle size and particle habit and are used to develop new scattering models for a suite of moderate-resolution imaging spectoradiometer (MODIS) bands spanning visible, near-infrared, and infrared wavelengths. The sensitivity of the resulting scattering properties to the underlying assumptions of the assumed particle size and habit distributions are examined. It is found that the near-infrared bands are sensitive not only to the discretization of the size distribution but also to the assumed habit distribution. In addition, the results indicate that the effective diameter calculated from a given size distribution tends to be sensitive to the number of size bins that are used to discretize the data and also to the ice-crystal habit distribution.
Gupta, Shashi K.; Kratz, David P.; Stackhouse, Paul W.; Wilber, Anne C.Gupta, S. K., D. P. Kratz, P. W. Stackhouse, A. C. Wilber, 2001: The Langley Parameterized Shortwave Algorithm (LPSA) for Surface Radiation Budget Studies. 1.0. An efficient algorithm was developed during the late 1980's and early 1990's by W. F. Staylor at NASA/LaRC for the purpose of deriving shortwave surface radiation budget parameters on a global scale. While the algorithm produced results in good agreement with observations, the lack of proper documentation resulted in a weak acceptance by the science community. The primary purpose of this report is to develop detailed documentation of the algorithm. In the process, the algorithm was modified whenever discrepancies were found between the algorithm and its referenced literature sources. In some instances, assumptions made in the algorithm could not be justified and were replaced with those that were justifiable. The algorithm uses satellite and operational meteorological data for inputs. Most of the original data sources have been replaced by more recent, higher quality data sources, and fluxes are now computed on a higher spatial resolution. Many more changes to the basic radiation scheme and meteorological inputs have been proposed to improve the algorithm and make the product more useful for new research projects. Because of the many changes already in place and more planned for the future, the algorithm has been renamed the Langley Parameterized Shortwave Algorithm . energy budgets; atmospheric radiation; Algorithms; spatial resolution; meteorological parameters
Loeb, Norman G.; Priestley, Kory J.; Kratz, David P.; Geier, Erika B.; Green, Richard N.; Wielicki, Bruce A.; Hinton, Patricia O’Rawe; Nolan, Sandra K.Loeb, N. G., K. J. Priestley, D. P. Kratz, E. B. Geier, R. N. Green, B. A. Wielicki, P. O. Hinton, S. K. Nolan, 2001: Determination of Unfiltered Radiances from the Clouds and the Earth’s Radiant Energy System Instrument. Journal of Applied Meteorology, 40(4), 822-835. doi: 10.1175/1520-0450(2001)040<0822:DOURFT>2.0.CO;2. Abstract A new method for determining unfiltered shortwave (SW), longwave (LW), and window radiances from filtered radiances measured by the Clouds and the Earth’s Radiant Energy System (CERES) satellite instrument is presented. The method uses theoretically derived regression coefficients between filtered and unfiltered radiances that are a function of viewing geometry, geotype, and whether cloud is present. Relative errors in instantaneous unfiltered radiances from this method are generally well below 1% for SW radiances (std dev ≈0.4% or ≈1 W m−2 equivalent flux), less than 0.2% for LW radiances (std dev ≈0.1% or ≈0.3 W m−2 equivalent flux), and less than 0.2% (std dev ≈0.1%) for window channel radiances. When three months (June, July, and August of 1998) of CERES Earth Radiation Budget Experiment (ERBE)-like unfiltered radiances from the Tropical Rainfall Measuring Mission satellite between 20°S and 20°N are compared with archived Earth Radiation Budget Satellite (ERBS) scanner measurements for the same months over a 5-yr period (1985–89), significant scene-type dependent differences are observed in the SW channel. Full-resolution CERES SW unfiltered radiances are ≈7.5% (≈3 W m−2 equivalent diurnal average flux) lower than ERBS over clear ocean, as compared with ≈1.7% (≈4 W m−2 equivalent diurnal average flux) for deep convective clouds and ≈6% (≈4–6 W m−2 equivalent diurnal average flux) for clear land and desert. This dependence on scene type is shown to be partly caused by differences in spatial resolution between CERES and ERBS and by errors in the unfiltering method used in ERBS. When the CERES measurements are spatially averaged to match the ERBS spatial resolution and the unfiltering scheme proposed in this study is applied to both CERES and ERBS, the ERBS all-sky SW radiances increase by ≈1.7%, and the CERES radiances are now consistently ≈3.5%–5% lower than the modified ERBS values for all scene types. Further study is needed to determine the cause for this remaining difference, and even calibration errors cannot be ruled out. CERES LW radiances are closer to ERBS values for individual scene types—CERES radiances are within ≈0.1% (≈0.3 W m−2) of ERBS over clear ocean and ≈0.5% (≈1.5 W m−2) over clear land and desert.
Whitlock, C. H.; Brown, D. E.; Chandler, W. S.; DiPasquale, R. C.; Ritchey, Nancy A.; Gupta, Shashi K.; Wilber, Anne C.; Kratz, David P.; Stackhouse, Paul W.Whitlock, C. H., D. E. Brown, W. S. Chandler, R. C. DiPasquale, N. A. Ritchey, S. K. Gupta, A. C. Wilber, D. P. Kratz, P. W. Stackhouse, 2001: Global Surface Solar Energy Anomalies Including El Niño and La Niña Years*. Journal of Solar Energy Engineering, 123(3), 211-215. doi: 10.1115/1.1384570. Weather anomalies that increase clouds influence the reliability of both renewable energy and building environmental-control systems. Non-grid solar power systems may run out of capacity for such items as communications electronics, flood-warning stream gages, refrigerators, and small village power systems. This paper provides 1×1-degree resolution global maps that identify those regions which experienced large abnormal solar energy during a 10-year period. A source is identified where specific values for maximum year-to-year variability can be obtained in regions where ground-site measurements do not exist. The information may aid in the selection of safety factors for solar power systems.
KRATZ, DAVID P.; ROSE, FRED G.KRATZ, D. P., F. G. ROSE, 1999: ACCOUNTING FOR MOLECULAR ABSORPTION WITHIN THE SPECTRAL RANGE OF THE CERES WINDOW CHANNEL. Journal of Quantitative Spectroscopy and Radiative Transfer, 61(1), 83-95. doi: 10.1016/S0022-4073(97)00203-3. Infrared active molecular species residing within the atmosphere cause the emerging thermal infrared spectrum of the Earth to be characterized by both line and continuum absorption (emission). Accounting for the molecular absorption within the atmosphere is critical for the proper interpretation of the satellite measured radiances. Thus, correlated k-distribution procedures have been created to account for the molecular line absorption located within the spectral range of the Clouds and the Earth’s Radiant Energy System (CERES) infrared window channel (8–12 μm). The derivation of the correlated k-distributions is based upon an exponential sum fitting of transmissions (ESFT) procedure that has been applied to monochromatic calculations at predetermined reference pressure and temperature conditions. In addition, an empirically derived, yet highly accurate parameterization of the CKD-2.1 code has been developed to calculate the atmospheric absorption attributed to the water vapor continuum located within the spectral range of the CERES infrared window channel. The multiplication transmissivity approximation has been employed to account for the overlap of the spectral features of different molecular species. The accuracy of the radiative transfer procedures incorporating the correlated k-distribution routines and the parameterized CKD2.1 continuum routines has been established through comparisons with the reference monochromatic procedures. The correlated k-distribution yields an upwelling top of atmosphere (TOA) flux for the midlatitude summer (MLS) atmosphere that is within 0.1% of the monochromatic procedures for the CERES window channel. Neglecting the contributions from all the molecular species in the correlated k-distribution except H2O and O3 yields an upwelling TOA flux for the MLS atmosphere with a 1.5% overestimation. Under circumstances where rapid processing is extremely critical, an error of this magnitude may be deemed acceptable. Neglecting the contributions from all of the molecular species yields an upwelling TOA flux for the MLS atmosphere with a 17.7% overestimation. An error of this magnitude is certainly not acceptable but does emphasize the need to account for the molecular absorption within the spectral range of the CERES window channel instrument.
Wilber, Anne C.; Kratz, David P.; Gupta, Shashi K.Wilber, A. C., D. P. Kratz, S. K. Gupta, 1999: Surface Emissivity Maps for Use in Satellite Retrievals of Longwave Radiation. Accurate accounting of surface emissivity is essential for the retrievals of surface temperature from remote sensing measurements, and for the computations of longwave radiation budget of the Earth?s surface. Past studies of the above topics assumed that emissivity for all surface types, and across the entire LW spectrum is equal to unity. There is strong evidence, however, that emissivity of many surface materials is significantly lower than unity, and varies considerably across the LW spectrum. We have developed global maps of surface emissivity for the broadband LW region, the thermal infrared window region , and 12 narrow LW spectral bands. The 17 surface types defined by the International Geosphere Biosphere Programme were adopted as such, and an additional surface type was introduced to represent tundra-like surfaces. Laboratory measurements of spectral reflectances of 10 different surface materials were converted to corresponding emissivities. The 10 surface materials were then associated with 18 surface types. Emissivities for the 18 surface types were first computed for each of the 12 narrow spectral bands. Emissivities for the broadband and the window region were then constituted from the spectral band values by weighting them with Planck function energy distribution. energy budgets; atmospheric radiation; Biosphere; broadband; computation; emissivity; infrared windows; lithosphere; long wave radiation; spectral bands; spectral reflectance; surface properties; surface temperature; temperature sensors; tundra
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
