Characterization of the microphysics of ice in tropical convection

Megha-Tropiques is a joint satellite between France and India to study the water and energy cycle in the Tropics. The satellite is part of GPM and provides an exceptional sampling of the 23° S-23° N region because of the low inclination of its orbit (20°) combined with the large swath (1700 km) of its main instrument MADRAS. The latter is a 9-channel passive microwave radiometer dedicated mainly to precipitation retrieval. Bauer et al (2005) showed that the most critical source of uncertainties in the precipitation retrieval over land comes from the ice microphysics characteristics. In the framework of the Megha-Tropiques mission we tried to improve the parameterization of precipitating ice in the radiative transfer model.

Datasets from two field experiments (Niamey 2010 and Gan 2011) will be used here. These campaigns were specifically designed to improve our knowledge of the ice categories found in the tropical convection. A combination of ground-based (X and S-band) and airborne (W-band) radars was used in conjunction with in-situ probes for microphysics. We will show some comparisons of Particles IDentification (PID) made from the various polarimetric radars in continental Africa and Indian Ocean with the images from these probes. The main idea here is to combine polarimetric radar data and microphysics in-situ measurements, both acquired during the two campaigns to demonstrate the coherence between PID (Particles IDentificator) classification and the microphysical characterization of the ice particles. This analysis will serve as a base to support the construction of a more “climatological” characterization of the ice depending on the convective features: life cycle, environment, season, etc… This climatology will then be compared with the brightness temperature at 89 GHz and 157 GHz of MADRAS.