Simultaneous retrieval of aerosol and coastal ocean properties by optimal estimation

Abstract

We analyze Sea Viewing Wide Field‐Of‐View Sensor (SeaWiFS) images over the Santa Barbara Channel. Pixel‐by‐pixel measurements of radiances at 8 SeaWiFS channels and analytic Jacobians are simulated using a coupled atmosphere‐ocean radiative transfer model. The retrival algorithm is based on optimal estimation with loosely constrained a priori data. The 5‐element state vector has two aerosol (optical depth at 865 nm, bimodal fraction of particles) and three marine parameters (chlorophyll concentration, detrital/dissolved‐matter absorption at 443 nm, and backscattering coefficient at 443 nm). The retrieval is stable and well posed; the results are smoother and show less spread than those derived from the standard SeaDAS v4.8 algorithm. Water‐leaving radiances agree well with field measurements. The average radiance residual is less than 1% for 7 SeaWiFS channels, and less than 2% for the 765 nm channel.