The calibration of the DSCOVR EPIC multiple visible channel instrument using MODIS and VIIRS as a reference

Conor Haney; David Doelling; Patrick Minnis; Rajendra Bhatt; Benjamin Scarino; Arun Gopalan

doi:10.1117/12.2238010

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19 September 2016 The calibration of the DSCOVR EPIC multiple visible channel instrument using MODIS and VIIRS as a reference

Conor Haney; David Doelling; Patrick Minnis; Rajendra Bhatt; Benjamin Scarino; Arun Gopalan

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Proceedings Volume 9972, Earth Observing Systems XXI; 99720P (2016) https://doi.org/10.1117/12.2238010
Event: SPIE Optical Engineering + Applications, 2016, San Diego, California, United States

Abstract

The Deep Space Climate Observatory (DSCOVR), launched on 11 February 2015, is a satellite positioned near the Lagrange-1 (L1) point, carrying several instruments that monitor space weather, and Earth-view sensors designed for climate studies. The Earth Polychromatic Imaging Camera (EPIC) onboard DSCOVR continuously views the sun illuminated portion of the Earth with spectral coverage in the UV, VIS, and NIR bands. Although the EPIC instrument does not have any onboard calibration abilities, its constant view of the sunlit Earth disk provides a unique opportunity for simultaneous viewing with several other satellite instruments. This arrangement allows the EPIC sensor to be intercalibrated using other well-characterized satellite instrument reference standards. Two such instruments with onboard calibration are MODIS, flown on Aqua and Terra, and VIIRS, onboard Suomi-NPP. The MODIS and VIIRS reference calibrations will be transferred to the EPIC instrument using both all-sky ocean and deep convective clouds (DCC) ray-matched EPIC and MODIS/VIIRS radiance pairs. An automated navigation correction routine was developed to more accurately align the EPIC and MODIS/VIIRS granules. The automated navigation correction routine dramatically reduced the uncertainty of the resulting calibration gain based on the EPIC and MODIS/VIIRS radiance pairs. The SCIAMACHY-based spectral band adjustment factors (SBAF) applied to the MODIS/ VIIRS radiances were found to successfully adjust the reference radiances to the spectral response of the specific EPIC channel for over-lapping spectral channels. The SBAF was also found to be effective for the non overlapping EPIC channel 10. Lastly, both ray-matching techniques found no discernable trends for EPIC channel 7 over the year of publically released EPIC data.

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Conor Haney, David Doelling, Patrick Minnis, Rajendra Bhatt, Benjamin Scarino, and Arun Gopalan "The calibration of the DSCOVR EPIC multiple visible channel instrument using MODIS and VIIRS as a reference", Proc. SPIE 9972, Earth Observing Systems XXI, 99720P (19 September 2016); https://doi.org/10.1117/12.2238010