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Classification of cloud radar signals

By analysing advanced radar signal features, such as temporal and spatial textures, and spectral and polarimetric structures, the retrieval of basic cloud parameters, as used for weather forecasts and climate research, will be improved.

A millimeterwave radar for cloud detection was introduced by METEK (GERMANY) several years ago. It is based on a transmitter technology developed at the INSTITUTE OF RADIO ASTROMY (UKRAINE). The radar 'MIRA36' has become well-known for its high quality and very competitive price. Nevertheless the number of sold systems remained modest (4 since the introduction into the market in 2002). A fundamental and significant shortcoming of this measuring technique is that most important physical cloud parameters cannot be derived unambiguously from radar data alone. Therefore the radar is typically used as one component within complex and expensive integrated sounding systems consisting for example of microwave radiometers, lidars or even radio soundings. This application is limited to major research centres or observatories of national weather services where this infrastructure is available, and the results are primarily used for research purposes rather than for operational application. The main cloud parameters required for weather forecast and climate monitoring are: 1. Depths of the cloud, sometimes in several cloud layers. 2. Cloud coverage (per cloud layer). 3. Overlap-factor of cloud layers. 4. Characteristic droplet size. 5. Mass density of liquid water/ice water. 6. Optical depth. 7. Mass density of drizzle, rain water and snow. 8. In-cloud dynamics, particularly vertical air motion. Although there will be no single remote sensing system in the foreseeable future, which can provide all these parameters with adequate quality, we believe that the radar MIRA36 in its present or slightly modified configuration provides much more potential for cloud parameter retrievals than currently exploited. Preliminary case studies have been performed at the KONRAD-ZUSE-INSTITUT in Berlin, where advanced signal classification algorithms were applied to short data samples provided by Deutscher Wetterdienst. The promising results were the kick-off for this proposal. We plan to implement the project in close cooperation with the KONRAD-ZUSE-INSTITUTE, where the bulk of the mathematical algorithm development will take place. Further input is required from the INSTITUTE OF RADIO ASTRONOMY in Kharkov, UKRAINE, in order to expand the versatility of polarimetric data, which have proven to be extremely useful in the above mentioned pilot studies. While the development and principal proof of feasibility of the algorithms will be based on recorded raw data, the huge data rate (60 MegaHerz (MHz) sampling rate in two polarisation channels) request that the numerics have to be optimised with respect to computing time until they can be used in a real-time environment. Finally the algorithms must be tested in a longer (several months) field experiment together with reference data. Preferably this test will take place at a well equipped meteorological observatory. Keywords: meteorology, radar, clouds.
Acronym: 
KLARA
Project ID: 
4 016
Start date: 
01-01-2007
Project Duration: 
28months
Project costs: 
500 000.00€
Technological Area: 
High Frequency Technology, Microwaves
Market Area: 
Consulting services

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