The Meteorological Institute of the Rheinische Friedrich-Wilhelms Universität Bonn (MIUB) covers a wide spectrum of research topics from boundary-layer meteorology, mesoscale modelling, polar research, analysis of measured and modelled climate data, to remote sensing from the surface (including radar meteorology) and satellites. The group headed by Clemens Simmer concentrates on remote sensing of meteorological parameters (temperature, humidity, cloud liquid water and precipitation) and their use for validation of and assimilation in mesoscale models (e.g. the Lokalmodell of the German Weather Service).. The group operates several ground-based remote sensing instruments (laser ceilometer, infrared radiometer, 4 channel passive microwave radiometer and X-Band radar) and develops retrieval methods using a synergetic sensor approach. A main focus is on passive microwave radiometry with research ranging from the theory of radiative transfer to experimental work with a "state-of-the-art" microwave spectrometer especially designed for the remote sensing of clouds. The group is involved in the COST action 712 for the application of satellite microwave radiometry in meteorology. The group is funded externally by the German Research Foundation (DFG) by individual projects and by participation in a Special Research Area (SFB350) and a Graduierten-Kolleg, by EU, EUMETSAT (SEVIRI, LandSAF), Deutsche Bundesstiftung Umwelt, the German Weather Service (DWD), and several minor contributions from work done for industrial partners.