Regularization methods for the inversion of infrared nadir sounding observations are currently investigated. An iterative Runge-Kutta type method for nonlinear ill-posed problems has been implemented and its performance has been studied using synthetic measurements.
Comparisons with Tikhonov type inversion with a priori regularization parameter selection indicate that both methods are of similar accuracy; however, the Runge-Kutta method is less sensitive to regularization parameter variations.
Furthermore, vertical column density retrieval from nadir
infrared sounders such as AIRS will be used for validation of column densities retrieved from near infrared SCIAMACHY observations. Two closely related retrieval codes are used for L2 processing of SCIAMACHY
near infrared and AIRS mid infrared spectra. First results
of this intercomparison are shown
