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CERES/GEO Flux Temporal Interpolation

GEO Temporal Interpolation Description

  • 3-hourly geostationary clouds and fluxes are used to estimate the flux in between CERES measurements to take into account changing meteorology
  • GEO clear-sky and snow region derived fluxes are excluded from interpolation
  • The CERES instrument onboard Terra (10:30LT) or Aqua (13:30LT) are in sun-synchronous orbits limiting diurnal sampling
  • Differences between CERES/GEO and CERES-only temporal interpolation are explained for SW and LW

GEO Clouds and Fluxes Procedure

  • 5-satellite GEO 3-hourly pixel 8-km pixel radiances between 60°N and 60°S are calibrated against Terra-MODIS, which is well calibrated
  • GEO cloud properties are retrieved using a subset of the MODIS cloud retrieval code using only the visible and 11µm channel providing consistency between MODIS and GEO clouds
  • The GEO broadband radiance are estimated from narrowband to broadband relationships using coincident MODIS/GEO measurements using the CERES ADM scene types
  • GEO broadband radiances are converted to flux using CERES ADM
  • GEO derived fluxes are regionally constrained to CERES flux observations, even if the GEO calibration is artificially adjusted by ±5% and the process is repeated, the global monthly flux bias is ~0.1W/m2 and the regional RMS error <1 W/m2
  • GEO fluxes maintain CERES calibration, free of GEO artifacts
  • More information can be found in the SYN Data Quality Summary (DQS) link to external site

CERES-only (ERBE) Temporal Flux Interpolation Description

  • CERES-only follows the ERBE temporal interpolation algorithm (Young et al. 1998)
  • For the SW the ~600 scene type CERES-TRMM directional models (SZA vs albedo) are used to fill in the unobserved hourly increments. For most non-polar regions this assumes constant meteorology throughout the day based on the Terra (10:30 AM sun-synch) or Aqua (1:30PM) measurement time, since only one daytime measurement is usually observed. The scene types are based on the geo-type and the MODIS cloud optical depth, amount and phase. There were only 12 ERBE scenes based on the SW and LW fluxes. (TRMM based ADMs) link to external site
  • CERES-only (ERBE) LW land temporal interpolation uses a half-sine and constant nighttime fit if the daytime LW flux is greater than the nighttime flux, to fill in 24 hourly time steps during the day
  • CERES-only (ERBE) LW ocean and snow temporal interpolation uses linear interpolation, to fill in 24 hourly time steps during the day. It is assumed that there are no LW diurnal cycles over clear-sky ocean and snow surfaces
  • Differences between CERES/GEO and CERES-only temporal interpolation are explained for SW and LW.

CERES Data Product Information

  Image: NASA Logo NASA Official: Dr. Norman Loeb
Page Curator: Edward Kizer
Page Last Modified: 05/10/2018 11:56:54 EST
Site Last Modified: 07/30/2018 14:57:50 EST