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CERES Temporal Interpolation



Temporal Interpolation Description

  • The CERES instrument onboard Terra (10:30LT) or Aqua (13:30LT) are in sun-synchronous orbits limiting diurnal sampling
  • There are no CERES products that combine the Terra and Aqua observations
  • Linearly interpolation of cloud properties between CERES measurements is not sufficient to estimate the diurnal flux signal in between CERES measurements (ERBE temporal interpolation method), there are many regions with strong diurnal cycles
    • Regions with strong diurnal cycles include, maritime stratus region where clouds burn off during the day, land afternoon convective regions, and land daytime heating
    • The SSF1deg product uses ERBE temporal interpolation
    • ERBE temporal interpolation methodology
  • 3-hourly geostationary clouds and fluxes are used to estimate the flux in between CERES measurements to take into account changing meteorology (CERES temporal interpolation method)
  • Examples of ERBE and CERES temporal interpolation flux differences

Examples of ERBE and CERES temporal interpolation flux differences

Image: Drawing of CERES Temporal Interpolation Comparison of the ERBE and CERES SW flux temporal interpolation over a Peruvian maritime stratus region over the course of one day.
Image: Comparison Temporal Interpolation Plots Comparison of Terra minus Aqua ERBE temporal interpolation vs Terra minus Aqua CERES temporal interpolation of monthly mean regional SW fluxes.
Image: Comparison Temporal Interpolation Plots Comparison of ERBE minus CERES temporal interpolation of SW monthly mean regional fluxes.
Image: Comparison Temporal Interpolation Plots Comparison of ERBE and CERES LW flux temporal interpolation over clear-sky desert.
Image: Comparison Temporal Interpolation Plots The CERES LW flux temporal interpolation is not symmetric about noon.
Image: Comparison Temporal Interpolation Plots Comparison of ERBE minus CERES temporal interpolation of LW monthly mean regional fluxes.

CERES Temporal Interpolation Procedure

  • 3-hourly geostationary clouds and fluxes are used to estimate the flux in between CERES measurements to take into account changing meteorology between 60° N and 60° S
    • The CERES instrument onboard Terra (10:30LT) or Aqua (13:30LT) are in sun-synchronous orbits limiting diurnal sampling
  • CERES SW temporal interpolation uses directional models based on scene type. Directional models relate solar zenith angle with albedo. There are ~600 CERES ADMs types based on imager cloud properties, geo surface types.
    • First the MODIS and GEO cloud properties are derived
    • Second fill in the hourly increments during the day with the observed CERES and GEO fluxes
    • Third, to estimate the flux between observations, use the 2 directional models based on the scene types of the preceding and following observations at a given unfilled hour increment and average them
    • For clear-sky SW use the ERBE interpolation fluxes, since it is assumed that the clear-sky albedo is symmetric about noon
    • Over snow regions it is assumed that geostationary cloud properties are not of quality and ERBE temporal interpolation is used, also over a bright surface there is little modulation of the SW by clouds
  • CERES LW temporal interpolation uses linear interpolation using both CERES and geostationary observed LW fluxes.
    • For clear-sky land the ERBE half sine fit is used due to scarcity of clear-sky measurements

CERES Data Product Information

 
  Image: NASA Logo NASA Official: Dr. Norman Loeb
Page Curator: Edward Kizer
Page Last Modified: 10/16/2017 11:04:36 EST
Site Last Modified: 11/07/2017 17:18:43 EST