Retrieval of atmospheric temperature and water vapour from IASI measurements in partly cloudy situations Original Research Article

The Infrared Atmospheric Sounding Interferometer (IASI), that will be flown on Metop, is a nadir sounding instrument for the measurement of high-resolution atmospheric temperature and water-vapour profiles as well as other trace gases. Due to the opacity of clouds in the infrared domain the profile retrievals are likely perturbed by undetected clouds, partly filling the field of view of the instrument. The huge amount of spectral information contained in the IASI measurements is used to account for the effect of undetected clouds in the profile retrieval. Numerical simulations show that the water-vapour and temperature retrievals are not degraded if the cloud amount in single pixels is less than 5% and the occurrence of clouds is accounted for in the retrieval scheme.