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Original Research Papers

Doppler radar radial winds in HIRLAM. Part II: optimizing the super-observation processing

Authors:

K. Salonen ,

Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, FI
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H. Järvinen,

Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, FI
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G. Haase,

Swedish Meteorological and Hydrological Institute, Norrköping, SE
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S. Niemelä,

Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, FI
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R. Eresmaa

Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, FI
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Abstract

Doppler radar radial wind observations are modelled in numerical weather prediction (NWP) within observation errors which consist of instrumental, modelling and representativeness errors. The systematic and random modelling errors can be reduced through a careful design of the observation operator (Part I). The impact of the random instrumental and representativeness errors can be decreased by optimizing the processing of the so-called super-observations (spatial averages of raw measurements; Part II).

The super-observation processing is experimentally optimized in this article by determining the optimal resolution for the super-observations for differentNWPmodel resolutions. A 1-month experiment with the HIRLAM data assimilation and forecasting system is used for radial wind data monitoring and for generating observation minus background (OmB) differences. The OmB statistics indicate that the super-observation processing reduces the standard deviation of the radial wind speedOmBdifference, while themean vectorwindOmBdifference tends to increase. The optimal parameter settings correspond at a measurement range of 50 km (100 km) to an averaging area of 1.7 km2 (7.3 km2).

In conclusion, an accurate and computationally feasible observation operator for the Doppler radar radial wind observations is developed (Part I) and a super-observation processing system is optimized (Part II).

How to Cite: Salonen, K., Järvinen, H., Haase, G., Niemelä, S. and Eresmaa, R., 2009. Doppler radar radial winds in HIRLAM. Part II: optimizing the super-observation processing. Tellus A: Dynamic Meteorology and Oceanography, 61(2), pp.288–295. DOI: http://doi.org/10.1111/j.1600-0870.2008.00381.x
  Published on 01 Jan 2009
 Accepted on 5 Nov 2007            Submitted on 5 Nov 2007

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