A multisensor approach toward a better understanding of snowfall microphysics the tosca project

An overview of the goals of the Towards an Optimal Estimation-based Snow Characterizing Algorithm (TOSCA) project, the applied instrumentation, and first results obtained from a measurement campaign in the winter of 2008/09, is provided. The project, funded by the German Science Foundation (DFG), focus is on the development of improved measurement techniques for snow and supercooled liquid water (SLW) at temperatures below freezing throughout the atmospheric column. Results show that ground-based MWR measurements at 90- and 150-GHz measurements are sensitive not only to liquid water but also to column snow water content. By simultaneously analyzing temperature and particle size measurements, the theory of the existence of a secondary aggregation growth region around -12° to -15°C is supported. Vertical profiling of snow-bearing clouds are found to remain one of the greatest and intriguing challenges of Earth science in the upcoming years, which propels our effort toward a ground-validation approach of snow microphysical processes.