The inverse module: δ-IASI

The module δ-IASI is the inverse module. This inversion module has been designed to retrieve: skin temperature, atmospheric profiles of temperature, water vapour and ozone by inverting highly resolved infrared radiance.

The algorithm we have implemented is mostly intended for the Infrared Atmospheric Sounding Interferometer (IASI), but the code is well suited for any nadir viewing satellite and airborne infrared sensor with a sampling rate in the range of 0.1-2 cm-1. The inversion scheme (described into details in Carissimo et al. 2005) is based on a Netwon-Raphson scheme in which the Radiative Transfer Equation is step-linearized by Taylor expansion.

Synthetic spectra and Jacobians are computed using σ-IASI which is a subroutine of δ-IASI. The software package for δ-IASI already includes its own version of the IASI forward module and therefore is completely independent of the σ-IASI software package.

Application of the whole package developed for IASI instrument can be found in Grieco et al. 2007, Masiello et al. 2009 and Grieco et al. 2010.

The functionality of δ-IASI software package is set up to be as independent as possible of the details of the computer environment in which it runs. The code has a size ofalmost 1 GB (including the storage amount of optical depth data-base) and the current version runs on linux and windows platform with the Intel Compiler.