Results of a comparison of radiative transfer models for simulating AIRS radiances

At the workshop for Soundings from High Spectral Resolution Observations in May 2003, an AIRS radiative transfer model comparison was proposed under the auspices of the ITWG. Results from 14 models have been submitted. The aim of the intercomparison was (i) to compare the forward model calculations for all AIRS channels from all models for 52 diverse profiles and one tropical Pacific profile coincident with AIRS data; (ii) to estimate forward model error covariances; (iii) to assess the jacobians from each model using a measure of fit for a limited selection of channels; and (iv) to document the time taken to run each model. Preliminary results of this inter-comparison are presented in this paper. For the forward model calculations most models agree to within 0.02K when compared to a reference model RFM. When compared with observations however the mean differences increase to 1K. For the jacobians all models have some profiles/channels that do not fit the RFM reference well.