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Operational Radar Measurements of Rainfall: The Accuracy of Point Estimates of Rainfall Rate

  • Marjan Divjak

Summary

A C-band weather radar was used to measure rainfall rates over mountainous terrain in Slovenia. Radar reflectivities were converted to radar-estimated surface rainfall rate using the standard Z R relation and compared with the 10-minute mean rainfall rate measurements based on a surface raingauge network. The following was found.
  1. 1

    Radar-estimated and gauge-measured point rainfall rates are correlated. Regression lines are strongly influenced by the relatively few extreme points at high rainfall rates.

     
  2. 2

    Radar measurements lead to the systematic range dependent underestimation of the point rainfall rates: ratios between the mean radar and mean gauge estimates vary from 1.0 at close ranges to 0.2 at long ranges.

     
  3. 3

    Radar estimates exhibit large scattering: percentage of occurrences that the radar estimates lie between 3 and 1/3 times the regression value is approximately 70%.

    The main cause for the underestimation and scattering are physical in origin: the inability to perform radar measurements close to the ground due to the orography and radar beam geometry, and the high spatial and temporal variations of precipitation.

     

Keywords

Rainfall Rate Radar Measurement Radar Reflectivity Weather Radar Large Scattering 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. (1).
    Brownscombe, J.L. and B.D. Hems, 1989: Comparison of radar precipitation measurements with a dense network of daily raingauges — applications to radar networking. Weather radar networking, Seminar on COST project 73, 426–433. Commission of the European Communities, Brussels.Google Scholar
  2. (2).
    Harrold, T. W. et al., 1974: The accuracy of radar-derived rainfall measurements in hilly terrain. Quart. J. R. Met. Soc., 100, 331–350.ADSCrossRefGoogle Scholar
  3. (3).
    Joss, J. and G. Galli, 1981: Digital radar informations in the Swiss Meteorological Institute. Preprints 20th Conference on radar meteorology. Am. Met. Soc., Boston.Google Scholar
  4. (4).
    Joss, J. and A. Waldvogel, 1990: Precipitation measurement and hydrology. Radar in meteorology, 577–618. Am. Met. Soc., Boston.Google Scholar
  5. (5).
    Messaoud, M. and Y. B. Pointin, 1990: Small time and space measurements of the mean rainfall rate made by gage network and by a dual-polarisation radar. J. Appl. Meteor., 29, 830–841.ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1992

Authors and Affiliations

  • Marjan Divjak
    • 1
  1. 1.Hydrometeorological Institute of SloveniaLjubljana, SloveniaYugoslavia

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