Passive remote sensing of altitude and optical depth of dust plumes using the oxygen A and B bands: First results from EPIC/DSCOVR at Lagrange-1 point

We presented an algorithm for inferring aerosol layer height (ALH) and optical depth (AOD) over ocean surface from radiances in oxygen A and B bands measured by the Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) orbiting at Lagrangian-1 point. The algorithm was applied to EPIC imagery of a 2 day dust outbreak over the North Atlantic Ocean. Retrieved ALHs and AODs were evaluated against counterparts observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer, and Aerosol Robotic Network. The comparisons showed 71.5% of EPIC-retrieved ALHs were within ±0.5 km of those determined from CALIOP and 74.4% of EPIC AOD retrievals fell within a ± (0.1 + 10%) envelope of MODIS retrievals. This study demonstrates the potential of EPIC measurements for retrieving global aerosol height multiple times daily, which are essential for evaluating aerosol profile simulated in climate models and for better estimating aerosol radiative effects. Plain Language Summary DSCOVR is a satellite parked at Lagrange-1 point, ~1.5 million kilometers from Earth. It was launched in February 2015 and started the data collection in June 2015. It carries a sensor called EPIC that looks at the sunlit surface every 1 to 2 h. This paper presents a new technique to retrieve dust optical depth and dust altitude from EPIC’s measurements within and outside of oxygen A and B absorptionbands. The results are validatedwithMODIS andCALIOPdata. The technique represents, for thefirst time, that we can reliably retrieve dust plume height from passive remote sensing multiple times a day.