09 Aug 2023
 | 09 Aug 2023

Shortwave reflected energy from NISTAR and the Earth Polychromatic Imaging Camera onboard the DSCOVR spacecraft

Clark Jay Weaver, Jay Herman, Alexander Marshak, Steven R. Lorentz, Yinan Yu, Allan W. Smith, and Adam Szabo

Abstract. We describe a new method for estimating the total reflected shortwave energy from the Earth Polychromatic Imaging Camera (EPIC) and compare it with direct measurements from the NIST Advanced Radiometer (NISTAR) instrument (Electrical substitution radiometer) – both are onboard the Lagrange-1 orbiting Deep Space Climate Observatory (DSCOVR). The 6 narrow-band wavelength channels (340 to 780 nm) available from EPIC provide a framework for estimating the integrated spectral energy for each EPIC pixel. The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the SCIAMACHY instrument provide spectral information away from the EPIC wavelengths, particularly for wavelengths longer than 780 nm. The total area-weighted reflected shortwave energy from an entire EPIC image is compared with co-temporal Band B Shortwave reflected energy observed by NISTAR. Our analysis from March to December 2017 shows the two are highly correlated with differences ranging from -10 to 10 Watts m-2. The offset bias over the entire period is less than 0.2 Watts m-2. We also compare our EPIC energy maps with the Clouds and the Earth’s Radiant Energy System (CERES) Single Scanner Footprint (SSF) Shortwave (SW) reflected energy observed within 3 hours of an EPIC image. Our EPIC-AVIRIS SW estimate is 5–20 % higher near the EPIC image center and 5–20 % lower near the image edges compared with the CERES SSF.

Clark Jay Weaver et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-638', François-Marie Bréon, 27 Aug 2023
  • RC2: 'Comment on egusphere-2023-638', Anonymous Referee #1, 29 Aug 2023
  • RC3: 'Comment on egusphere-2023-638', Anonymous Referee #3, 04 Sep 2023

Clark Jay Weaver et al.

Clark Jay Weaver et al.


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Short summary
We calculate the total amount of solar energy reflected by the earth from the EPIC camera onboard the DSCOVR satellite positioned 1.5 million km from earth. We compare it with another estimate of the reflected energy from the NISTAR instrument, that is also on the DSCOVR satellite. Both energy estimates agree within the uncertainties of each instrument. Finally, we compare with a third estimate of solar reflected energy from the CERES instruments that are on board low-earth orbit satellites.