Simulating PACE Ocean Observing Capabilities

The PACE mission is intended to observe the global oceans at hyper-spectral resolution to help identify new biological components poorly resolved, if resolved at all, by modern moderate resolution ocean color sensors. Of particular emphasis is the detection of abundances and distributions of phytoplankton functional/taxonomic groups. To assist in pre-launch mission assessment capabilities, we have developed a PACE ocean simulation system, which produces global fields of optically important ocean constituents at 1-nm spectral resolution. The system produces normalized water-leaving radiance by summing the contributions by water, four different phytoplankton groups, organic detritus, chromophoric dissolved organic matter (CDOM), and particulate inorganic carbon (PIC), all of which are represented in the model as prognostic variables (i.e., active constituents with independent source and sink parameterizations). Additionally, total chlorophyll, CDOM, and PIC are simultaneously assimilated to improve the fidelity of the simulated radiance fields. A one-year simulation showed statistically significant comparisons of chlorophyll (r=0.904), aCDOM (r=0.909), and PIC (r=0.994) with satellite data, and diatoms (r=0.830), cyanobacteria (r=0.702), and coccolithophores (r=0.661) with in situ data. The high spectral resolution of the simulation supports investigations of band selection for the mission. The global nature of the radiance representations supports investigations of various satellite observing scenarios. The multi-component optical representation supports investigations of mission capability.