The Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) Mission and its Polarimeters: Mission Update and Instrument Synergies

As the mission name indicates, the PACE mission will make observations of the oceans, aerosols and clouds; and for that matter the land surface. In particular, PACE will make new global measurements of ocean color that are essential for understanding the global carbon cycle & ocean ecosystem responses to a changing climate, and collect global observations of aerosol & cloud properties, focusing on reducing the largest uncertainties in climate & radiative forcing models of the Earth system. To that end the PACE mission includes a UV-SWIR imaging spectrometer and 2 multi-angle UV-NIR polarimeters. The primary instrument is the UV-SWIR imaging spectrometer, the Ocean Color Instrument (OCI), with continuous spectral coverage at 5 nm resolution from 350-865 nm together with discrete spectral bands at 940, 1038, 1250, 1378, 1615, 2130 and 2260 nm; 1 km resolution at nadir and two-day global coverage. In addition, PACE will have a hyperspectral polarimeter, the Spectro-Polarimeter for Planetary Exploration (SPEXone) contributed by a consortium consisting of Airbus Defense Space Netherlands (ADSN) and SRON from the Netherlands and a hyperangular polarimeter, the Hyper Angular Rainbow Polarimeter (HARP2), contributed by the University of Maryland Baltimore County. SPEXone has continuous spectral coverage from 385-770 nm at 2-5nm resolution with expected polarimetric accuracy of 0.003, 2.5 km spatial sampling and five viewing angles over ±57° from nadir. HARP2 has expected polarimetric accuracy of better than 0.01, 3.0 km spatial sampling with 10 viewing angles over ±57° from nadir in bands at 443, 550 and 865 nm and 60 viewing angles in a band at 670 nm. With the PACE observatory having completed all its environmental testing and launch planned for January 2024, this talk will provide updates on the performance of the PACE instruments and how they will work together to provide the best possible atmospheric and oceanic retrieval products.