30 May 2022
30 May 2022
Status: this preprint is currently under review for the journal AMT.

Algorithm Theoretical Basis for Ozone and Sulfur Dioxide Retrievals from DSCOVR EPIC

Xinzhou Huang and Kai Yang Xinzhou Huang and Kai Yang
  • Department of Atmospheric and Oceanic Sciences, University Maryland, College Park, MD 20742, USA

Abstract. Onboard the Deep Space Climate Observatory (DSCOVR), the first Earth-observing satellite at the L1 point (the first Lagrangian point in the Earth-Sun system), the Earth Polychromatic Imaging Camera (EPIC) observes the entire sunlit face of the Earth continuously. EPIC measures the solar backscattered and reflected radiances in ten discrete spectral channels, four of which are in the ultraviolet (UV) range. These UV bands are selected primarily for total ozone (O3) and aerosol retrievals based on heritage algorithms developed for the series of Total Ozone Mapping Spectrometer (TOMS). These UV measurements also provide sensitive detection of sulfur dioxide (SO2) and volcanic ash, both of which may be episodically injected into the atmosphere during explosive volcanic eruptions. This paper presents the theoretical basis and mathematical procedures for the direct vertical column fitting (DVCF) algorithm used for retrieving total vertical columns of O3 and SO2 from DSCOVR EPIC. This paper describes algorithm advances, including an improved O3 profile representation that enables profile adjustments from multiple spectral measurements and the spatial optimal estimation (SOE) scheme that reduces O3 artifacts resulted from EPIC's band-to-band misregistrations. Furthermore, this paper discusses detailed error analyses and presents inter-comparisons with correlative data to validate O3 and SO2 retrievals from EPIC.

Xinzhou Huang and Kai Yang

Status: open (until 07 Jul 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-156', Anonymous Referee #1, 29 Jun 2022 reply
  • RC2: 'Comment on amt-2022-156', Anonymous Referee #2, 30 Jun 2022 reply

Xinzhou Huang and Kai Yang

Xinzhou Huang and Kai Yang


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Short summary
This paper describes the algorithm for O3 and SO2 retrievals from DSCOVR EPIC. Algorithm advances, including the improved O3 profile representation and the regulated direct fitting inversion technique, improve the accuracy of O3 and SO2 from the multi-channel measurements of DSCOVR EPIC. A thorough error analysis is provided to quantify O3 and SO2 retrieval uncertainties due to various error sources and simplified algorithm physics treatments.