DSCOVR EPIC Level 2 Total Ozone, Version 3

DSCOVR_EPIC_L2_TO3_v03 is Level2 Total Ozone derived from the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) using Level 1b version 3 inputs and version 3 ozone retrieval algorithm. The measurements from four EPIC UV channels are used to derive the global distributions of total ozone over the entire sunlit portion of the Earth. A new soft calibration technique developed based on scene matching with OMPS gives calibrated EPIC radiances. The calibrated EPIC radiances are used to derive science-quality total ozone products from EPIC that are consistent with those from other UV instruments. The retrieval algorithm uses wavelength triplets and assumes that the scene reflectivity changes linearly with wavelength. Version 3 algorithm includes several key modifications aimed to improve total ozone retrievals: a) switch to Version 3 Level 1b product with improved geolocation registration, flat field and dark counts corrections; b) replace OMI based cloud height climatology with the simultaneous EPIC A-Band cloud height; c) update absolute calibrations using polar orbiting SNPP OMPS; d) add corrections for ozone profile shape and temperature; e) update algorithm and error flags to filter data; f) add column weighting functions for each observation to facilitate error analysis. EPIC ozone retrievals accurately capture short term synoptic changes in total column ozone. With EPIC measurements from DSCOVR's vantage point synoptic ozone maps can be derived every 1-2 hours. Scene Reflectivity (clouds, aerosols, and surface) is derived as part of the ozone retrieval. The scene reflectivity in conjunction with ozone has been used to derive the amount of UV solar radiation reaching the ground, and surface UV Erythemal is also reported in these files.