Ways of Using, and Correcting for Errors in Conventional Radar Reflectivity Data

  • Jürg Joss


Over the years much research has been directed towards exploring the potential of radar as an instrument for estimating rain. It is shown that with the present reflectivity measuring radar, acceptable quantitative information is already obtained from radar networks in many places and in a wide range of applications. It is unlikely, however, that radar will ever replace the raingauge, since gauges are vital as ground truth for adjusting and/or checking the radar data. On the other hand, as pointed out by many workers, we would need an extremely dense and costly network of gauges to obtain a spatial resolution easily attainable with radar.

But radar will only estimate the precipitation it can “see”. Even the most ingenious procedure using sophisticated equipment will not allow us to make measurements in parts lost because of reduced visibility. Reduced visibility will occur behind mountains. But also at longer ranges, even in flat country, we will find increased errors due to losses caused by the earth curvature and the reduced resolution of the radar beam. Thanks to the availability of inexpensive, high-speed data processing equipment, it is possible today to determine the echo distribution in the whole radar coverage area in three dimensions. This knowledge, together with knowledge about the position of the radar and the orography around it, allows one to correct in real time for a large fraction of - or at least to estimate the magnitude of - the vertical profile problem. This correction allows us to extend the region in which an accuracy acceptable for many hydrological applications is obtained. This paper is in part based on the reviews by Joss and Waldvogel (1989) and Joss and Smith (1989), where the reader may find more details.


Rain Rate Radar Reflectivity Bright Band Short Term Forecast Weather Radar 
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  1. Austin, P.M. 1987: Relation between measured radar reflectivity and surface rainfall. Monthly Weather Review, pp 1053–1070.Google Scholar
  2. Browning, K.A., 1979: The FRONTIERS plan: a strategy for using radar and satellite imagery for very-short-range precipitation forecasting, Met. Mag, 108, pp 161–184.Google Scholar
  3. Cluckie, I.D., P.F. Ede, M.D. Owens, A.C. Bailey and C.G. Collier, 1987: Some hydrological aspects of weather radar research in the United Kingdom. Hydrological Sciences Journal, 32, 3, 9/1987.CrossRefGoogle Scholar
  4. Collier, C.G., 1985: Remote sensing for Hydrology. Facets of Hydrology, Volume II, Chapter 1, John Wiley Sons Ltd.Google Scholar
  5. Collier, C.G., 1986: Accuracy of rainfall estimates by radar, Part I: Calibration by telemetering raingauges. Journal of Hydrology, 83 (1986) 207–223.CrossRefGoogle Scholar
  6. Conway, J.B., 1987: FRONTIERS: An operational system for nowcasting precipitation. Proc. Symp. Mesoscale Analysis and Forecasting, Vancouver, ESA SP-282, pp 233–239.Google Scholar
  7. Golden, J., E.D. Sarreals and F. Toepfer, 1986: NEXRAD products and algorithms, Part II: Operational impact of NEXRAD technology on NWS operations. Preprints 23rd Conference on Radar Meteorology, Vol. 3, pp JP87–90, AMS, Boston.Google Scholar
  8. Joss, J. and A. Waldvogel, 1989: Precipitation measurements. To appear in the CIMO-Guide, Editor: Marc Gilet.Google Scholar
  9. Joss, J. and A. Waldvogel, 1989: Precipitation measurements and Hydrology, a Review. To appear in the Battan Memorial and 40th Anniversary Radar Meteorology Volume, Editor: David Atlas.Google Scholar
  10. Kappenberger, G. and J. Joss, 1986: Use of radar and automatic weather stations in avalanche forecasting. Proceedings of the International Conference on Formation, Mouvement and Avalanches, IAHS No. 162, Wallingford, GB, pp 305–310.Google Scholar
  11. King, P. and T.C. Yip, 1987: Evaluation of the rainsat precipitation analysis system in real-time use. Proc. Symp. Mesosocale Analysis and Forecasting, Vancouver, ESA SP-282, pp 263–268Google Scholar
  12. Koistinen, J., 1986: The Effect of some Measurement Errors on Radar-Derived Z-R Relationships. Preprints 23rd Conference on Radar Meteorology, Vol. 3, pp JP50–53, AMS, Boston.Google Scholar
  13. Rogers, R.R. and M. K. Yau, 1981: Summertime radar echo coverage at Montreal. Preprints 20th Conference on Radar Meteorology Boston, Mass. Published by the Am. Met. Soc., Boston, 469–475.Google Scholar
  14. Passarelli, R.E., P. Romanik, S.G. Geotis and A.D. Siggia, 1981: Ground clutter rejection in the frequency domain. Preprints 20th Conference on Radar Meteorology Boston, Mass. Published by the Am. Met. Soc., Boston, 295–300.Google Scholar
  15. Ulbrich, C.W. and D. Atlas, 1984: Assessment of the contribution of differential polarization to improve rainfall. Radio Science, Vol. 19, Nr. 1, Jan-Feb 1984, pp 49–57.CrossRefGoogle Scholar

Copyright information

© ECSC, EEC, EAEC, Brussels and Luxembourg 1990

Authors and Affiliations

  • Jürg Joss
    • 1
  1. 1.Swiss Meteorological Institute Osservatorio TicineseLocarno MontiSwitzerland

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