Atmospheric Correction of DSCOVR EPIC: Version 2 MAIAC Algorithm

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https://www.frontiersin.org/articles/10.3389/frsen.2021.748362/full

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https://doi.org/10.3389/frsen.2021.748362
 http://hdl.handle.net/11603/28811

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UMBC Joint Center for Earth Systems Technology (JCET)
UMBC Faculty Collection
UMBC GESTAR II

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https://orcid.org/0000-0002-0223-309X
 https://orcid.org/0000-0002-2488-2840
 https://orcid.org/0000-0003-4690-3232

Date

2021-09-20

Type of Work

journal articles
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Citation of Original Publication

Lyapustin A, Wang Y, Go S, Choi M, Korkin S, Huang D, Knyazikhin Y, Blank K and Marshak A (2021) Atmospheric Correction of DSCOVR EPIC: Version 2 MAIAC Algorithm. Front. Remote Sens. 2:748362. doi: 10.3389/frsen.2021.748362

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

The Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) provides multispectral images of the sunlit disk of Earth since 2015 from the L1 orbit, approximately 1.5 million km from Earth toward the Sun. The NASA’s Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm has been adapted for DSCOVR/EPIC data providing operational processing since 2018. Here, we describe the latest version 2 (v2) MAIAC EPIC algorithm over land that features improved aerosol retrieval with updated regional aerosol models and new atmospheric correction scheme based on the ancillary bidirectional reflectance distribution function (BRDF) model of the Earth from MAIAC MODIS. The global validation of MAIAC EPIC aerosol optical depth (AOD) with AERONET measurements shows a significant improvement over v1 and the mean bias error MBE = 0.046, RMSE = 0.159, and R = 0.77. Over 66.7% of EPIC AOD retrievals agree with the AERONET AOD to within ± (0.1 + 0.1AOD). We also analyze the role of surface anisotropy, particularly important for the backscattering view geometry of EPIC, on the result of atmospheric correction. The retrieved BRDF-based bidirectional reflectance factors (BRF) are found higher than the Lambertian reflectance by 8–15% at 443 nm and 1–2% at 780 nm for EPIC observations near the local noon. Due to higher uncertainties, the atmospheric correction at UV wavelengths of 340, 388 nm is currently performed using a Lambertian approximation.