All-sky radiative transfer calculations for IASI and IASI-NG: The σ-IASI-as code

In the context of the development by EUMETSAT of a new generation of meteorological satellites, we have built the new σ-IASI-as (where “as” stands for “all sky”) radiative transfer code. Unlike its predecessor σ-IASI, the code is able to calculate both clear and cloudy sky radiances, as well as their Jacobians with respect to any desired geophysical parameter. In addition, σ-IASI-as can perform calculations to simulate the extinction effect of the most common types of atmospheric aerosols and of clouds via ab-initio Mie calculations. We briefly describe the analytical scheme on which the model is based, and have a glance to its potentialities illustrating some sample calculations. Overall, the new model is a complete and fast radiative transfer tool for IASI, and already available for IASI-NG and MTG-IRS.