Joint PACE HARP2 Aerosol and Ocean Color Retrievals with Uncertainty Assessment

The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission has been designed with the goal of studying the global ocean and atmosphere, with a focus on improving data records of ocean ecology, biogeochemistry, atmospheric aerosols, and clouds. The mission is equipped with state-of-the-art instruments, including the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two Multi-Angle Polarimeters (MAPs), namely the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and the SRON Spectro-Polarimeter for Planetary EXploration one (SPEXone). These MAP measurements hold a wealth of information that can be used to obtain aerosol and ocean color information simultaneously, and the PACE mission plans to produce a suite of advanced data products with high accuracy.

In this talk, we will discuss the HARP2 aerosol products, their data format, and expected uncertainties based on the FastMAPOL retrieval algorithm. The retrieval algorithm provides an efficient approach to simultaneously derive aerosol and ocean properties through Bayesian optimal estimation and deep learning based radiative transfer forward models. To understand the HARP2 retrievability, a full day of global synthetic HARP2 data were generated and used to test various retrieval parameters including aerosol complex refractive index, effective radius and variance, aerosol layer height, aerosol optical depth, and single scattering albedo. To assess the retrieval quality, pixel-wise retrieval uncertainties were derived based on error propagation and evaluated against the difference between the retrieval parameters and truth. Retrieval uncertainties for both fine and coarse mode aerosols, as well as ocean surface wind speed and ocean chlorophyll a, are examined with respect to location, geometries, and distribution of geophysical properties. Based on the retrieval results, advanced research products including multi-angle cloud masks and angular water leaving signals will be also investigated. This study will provide an overview on the retrieval algorithm, data products, and their associated uncertainties for HARP2 in preparation for the upcoming PACE mission.