Detecting layer height of smoke aerosols over vegetated land andwater surfaces via oxygen absorption bands: Hourly results fromEPIC/DSCOVR satellite in deep space

Abstract. We present an algorithm for retrieving aerosol layer height (ALH) and aerosol optical depth (AOD) for smoke over vegetated land and water surfaces from measurements of the Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR). The algorithm uses earth-reflected radiances in six EPIC bands in visible and near-infrared and incorporates flexible spectral fittings that account for specifics of land and water surface reflectivity. The fitting procedure first determines AOD using EPIC atmospheric window bands (443 nm, 551 nm, 680 nm, and 780 nm), then uses oxygen (O 2 ) A and B bands (688 nm and 764 nm) to derive the ALH that represents an optical centroid altitude. ALH retrieval over vegetated surface primarily takes advantage of the measurements in the O 2 B band. We applied the algorithm to EPIC observations of several biomass burning events over United State and Canada in August 2017. We found the algorithm can well capture AOD and ALH multiple times daily over water and vegetated land surface. Validations are performed against aerosol extinction profile detected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and AOD observed at nine Aerosol Robotic Network (AERONET) sites, showing, in average, an error of 0.58 km and a bias of −0.13 km in retrieved ALH and an error of 0.05 and a bias of 0.03 in retrieved AOD. Additionally, we show that the aerosol height information retrieved by the present algorithm can potentially benefit the retrieval of aerosol properties from the EPIC’s ultraviolet (UV) bands.