Expected improvements in the atmospheric humidity profile retrieval using the Megha-Tropiques microwave payload
Résumé
The microwave payload of the Megha-Tropiques mission is explored to quantify the expected improvements in the retrieval of relative humidity profiles. Estimations of the profiles are performed using a generalized additive model that uses cubic smoothing splines to address the nonlinear dependencies between the brightness temperatures (TB) in the 183.31 GHz band and the relative humidity of specified tropospheric layers. Under clear-sky and oceanic situations, the six-channel configuration of the SAPHIR radiometer clearly improves the retrieval and reduces by a factor of two the variance of the residuals with respect to the current space-borne humidity sounders that have three channels in this band (AMSU-B, MHS). Additional information from the MADRAS radiometer (at 23.8 and 157 GHz) further improves the restitution with correlation coefficient higher than 0.89 throughout the troposphere.