This project is part of the DFG priority program “Quantitative Precipitation Forecast”. It is based on the following hypotheses about the influence of water vapour and wind on the development of convection and precipitation:

• The quantitative precipitation forecast can be improved by initialisation of the water vapour and wind fields within the models, especially before the beginning of convection.
• The necessary data can be obtained by remote sensing measurement systems.
• The inclusion of data about water vapour and wind within clouds and precipitation systems enables a better initialisation of cloud water within the models.

Thus the main goals of the project are:

• Improvement of the initialisation of water vapour, wind and clouds in numerical weather forecast models using data of innovative measuring systems (LIDAR, GPS)
• Development of a short range forecast system for research purposes and operational use, based on extended data and improved data assimilation techniques
• Preparation of a short range forecast system for the “Intensive Observations  Program” (IOP-COPS) and the “General Observations Program” (GOP)

The IMK provides meteorological data with high resolution in time and space. These data are extracted from impoved in-situ vertical soundings with a patented drop sonde system  and conduce to calibration of GPS and LIDAR remote sensing systems. They are utilised for assimilation of data from the model system and for the evaluation of observation simulation experiments.

The drop sondes are equipped with dew point mirror as well as a particle and droplet counter. Up to 30 probes can be used during one measuring phase. They can either be dropped from an airplane or started from the ground. In the latter case the probes  measure both while ascending and descending. The ceiling of the sondes can be adjusted individually for each probe.

Vertical soundings of a cluster of dropsondes, each lauched on the knot of a model grid can be accomplished with this probes (see Fig.), and the three-dimensional measurements of wind and water vapour by LIDAR-Systems can be verified.

The project is performed by the Universities of Hohenheim, Dresden and Karlsruhe as well as by the GeoForschungsZentrum Potsdam. The project is coordinated by Hans-Stefan Bauer and Volker Wulfmeyer, Franz H. Berger, Gerd Gendt and Christoph Kottmeier.  

Schematic description of a clusterflight of 4 drop-up-sondes started at the knots of a model grid. The probes ascends with a balloon (1), fly on constant level (2) and descende with a parachute (3).