Tropical precipitation margins
Several studies, including analyses of critical feedbacks over Northern Africa undertaken by CliSAP, demonstrated the weakness of climate system models with respect to the precipitation distribution in the tropics. Hence it is proposed to assess tropical precipitation and monsoon margins as a function of representation of convection and the surface-atmosphere interaction on a wide range of temporal and spatial scales. The main emphasis will be placed on variability and its physical controls at intra-seasonal (Madden-Julian Oscillation - MJO) and longer time scales with a special focus on the Indo-Pacific Warm Pool and the land surfaces of the Amazon Basin and Africa. For the latter, feedbacks with fire dynamics and dust transports will be considered. In addition, the effects of the dynamics of the ITCZ on tropical precipitation, especially with respect to the West African monsoon, will be investigated. As mentioned above, the double ITCZ is accompanied by hitherto unexplained poleward propagating precipitation anomalies which need to be assessed. Modeling studies on tropical precipitation and monsoon margins will be complemented by data analyses. Over the ocean, already existing data, e.g. HOAPS, will be utilized. Over land, novel satellite remote sensing techniques that combine high resolution satellite sounding (IASI, AIRS) data with new remote sensing observations on soil moisture dynamics and surface fluxes (SMOS, HOLAPS) will help to better understand relevant processes and to characterize surface-atmosphere interactions in the regions under consideration on shorter time scales.