Atmospheric trace gases profile retrievals using the nonlinear regularized total least squares method |
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Authors: | Prabhat K Koner James R Drummond |
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Institution: | Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON, Canada M5S 1A7 |
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Abstract: | We discuss the regularized total least squares (RTLS) method for the nonlinear overdetermined ill-posed problem of atmospheric trace gas retrieval. The RTLS method is used for the automatic determination of the regularization strength of the ill-conditioned matrix in an iterative process, and a mixed quadratic and cubic line search method is used for the nonlinear retrievals. Additional retrieval metrics, such as the model resolution matrix and the degrees of freedom in the retrieval, which characterize the vertical resolution of the retrievals, are also derived. Simulated retrievals as well as the retrieval from the data of a balloon-based spectroscopic measurement will be discussed. Retrieval results obtained using O3 and CH4 as test cases will be presented. |
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Keywords: | Ill-posed inverse problems Regularization Degree of freedom of retrieval Total least squares Line search method Radiative transfer equation Atmospheric remote sounding |
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