Representation of cloud and precipitation processes is one of the largest sources of uncertainty in climate and weather predictions. This project aims at exploring the potential of the novel HALO microwave package (HAMP) for airborne cloud and precipitation research by participating in all cloud related missions of the research aircraft HALO. HAMP is a unique combination of a 23 channel microwave radiometer and a cloud radar. To make HAMP a valuable research instrument, we will develop synergistic retrieval algorithms which convert the measured passive and active microwave signals into profiles of temperature, humidity and hydrometeor content with corresponding error estimates. A comprehensive evaluation of HAMP with existing observational systems, like e.g. satellites and ground based remote sensing super-sites will allow an assessment of its added value. In particular, we will analyze whether HAMP can resolve the fine-scale structure of cloud and precipitation fields and can thus relate point observations with area averaged data from satellites and models. Finally, observations from the NARVAL campaign will be used to demonstrate the benefit of HAMP for model development by revising the frequently used model assumption that shallow convective clouds do not precipitate.

• Validation of satellite estimates of cloud properties and precipitation by performing detailed in situ and remote sensing observations of cloud vertical structure
• Perform process studies on cloud and precipitation for evaluating and improving cloud parameterizations in weather forecast and climate models