HR: 17:15h
AN: OS24B-05    [Abstracts]
TI: Simultaneous Retrieval of Aerosols and Ocean Color Using the Linearized CAO-DISORT Model: Improved SEAWiFS and MODIS Retrievals and Comprehensive Error Budgets
AU: * Spurr, R J
EM: rtsolutions@verizon.net
AF: RT SOLUTIONS Inc., 9 Channing Street, Cambridge, MA 02138 United States
AU: Stamnes, K H
EM: kstamnes@stevens-tech.edu
AF: Stevens Institute of Technology, Castle Point on Hudson , Hoboken, NJ 03070 United States
AU: Li, W
EM: wli@stevens.edu
AF: Stevens Institute of Technology, Castle Point on Hudson , Hoboken, NJ 03070 United States
AU: Eide, H
EM: heide@stevens.edu
AF: Stevens Institute of Technology, Castle Point on Hudson , Hoboken, NJ 03070 United States
AU: Zhang, K
EM: kzhang@stevens.edu
AF: Stevens Institute of Technology, Castle Point on Hudson , Hoboken, NJ 03070 United States
AU: Stamnes, J J
EM: JakobJ.Stamnes@fi.uib.no
AF: University of Bergen, Allegaten 55, Bergen, N-5007 Norway
AB: The coupled atmosphere-ocean discrete ordinate radiative transfer model CAO-DISORT has been given a linearization capability; we show that the entire radiation field is analytically differentiable with respect to any atmospheric or marine constituent parameter. One call to the linearized CAO-DISORT model will simultaneously generate simulated upwelling and/or downwelling radiance fields and analytic Jacobians for any viewing geometry and for any optical depth in either medium. The model also has a new pseudo-spherical capability for dealing with atmospheric solar beam attenuation in a curved spherical-shell atmosphere. With the linearized CAO-DISORT code as the forward model, we use iterative classical least squares inversion methods to perform simultaneous retrieval of aerosol and marine parameters. The retrieval is based on minimization of chi-square merit functions appropriate to a direct comparison measured and simulated top-of-atmosphere SeaWiFS and MODIS radiances. The state vector comprises two boundary layer aerosol parameters (total number density and bimodal fractional weighting) and one or two marine parameters (chlorophyll concentration and additional CDOM absorption in coastal waters). Information from all instrument channels is used in the inversion. We present an analysis of radiance residuals for a wide variety of SEAWiFS and MODIS scenes; retrievals are considerably more accurate that those obtained using traditional atmospheric correction and water-leaving radiance modeling approaches. Error sources are four-fold: TOA radiance instrument errors, uncertainty about model parameters assumed known but not actually retrieved, modelization errors due to forward model assumptions, and smoothing errors arising from a priori regularization. For a representative set of scenarios, we use the CAO-DISORT linearization capability in conjunction with the inverse code to generate contribution functions, averaging kernels and model parameter Jacobians, as required for the computation of these error sources. We present a detailed error and sensitivity analysis for SEAWiFS and MODIS ocean color and atmospheric aerosol retrievals; this is the first time that comprehensive error budgets have been drawn up for this remote sensing application.
DE: 3359 Radiative processes
DE: 3360 Remote sensing
DE: 4262 Ocean observing systems
DE: 4264 Ocean optics (0649)
DE: 4275 Remote sensing and electromagnetic processes (0689, 2487, 3285, 4455, 6934)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005