Alternate Transmission of +45° and −45° Slant Polarization and Simultaneous Reception of Vertical and Horizontal Polarization for Precipitation Measurement

Enrico Torlaschi Centre Coopératif pour la Recherche en Mésométéorologie, and Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, Montreal, Quebec, Canada

Search for other papers by Enrico Torlaschi in
Current site
Google Scholar
PubMed
Close
and
Yves Gingras Centre Coopératif pour la Recherche en Mésométéorologie, and Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, Montreal, Quebec, Canada

Search for other papers by Yves Gingras in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

A polarimetric weather radar with alternate transmission of slant linear +45° and −45° polarization and simultaneous reception of both linear vertical and linear horizontal polarization is considered. The equations of the radar observables for a model medium containing nonspherical hydrometeors are presented. Assuming the hydrometeors to be axially symmetric with a canting angle distribution symmetric about the mean canting angle, a set of equations for separation of propagation and backscattering effects is developed. The mean apparent canting angle, the degree of common orientation of the hydrometeors, and the differential phase shift are obtained. Using empirical relationships, the mean and differential attenuations are estimated by means of the differential phase shift. The intrinsic value of the reflectivity, the differential reflectivity, and the copolar correlation coefficient at zero lag time are then determined. Application of this to a model convective rain cell shows that the use of simultaneous transmission and reception of linear vertical and linear horizontal polarization at S, C, and X bands provides accurate estimates of the intrinsic scattering properties of precipitation. The analysis of the bias on the radar observables due to the assumption of a medium of equioriented hydrometeors shows that all the observables with the exception of reflectivity can be severely affected.

* Current affiliation: Environnement Canada, Centre Météorologique Canadien, Dorval, Quebec, Canada.

Corresponding author address: Enrico Torlaschi, Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, Case postale 8888, Succursale Centre-Ville, Montréal, PQ H3C 3P8, Canada.

Abstract

A polarimetric weather radar with alternate transmission of slant linear +45° and −45° polarization and simultaneous reception of both linear vertical and linear horizontal polarization is considered. The equations of the radar observables for a model medium containing nonspherical hydrometeors are presented. Assuming the hydrometeors to be axially symmetric with a canting angle distribution symmetric about the mean canting angle, a set of equations for separation of propagation and backscattering effects is developed. The mean apparent canting angle, the degree of common orientation of the hydrometeors, and the differential phase shift are obtained. Using empirical relationships, the mean and differential attenuations are estimated by means of the differential phase shift. The intrinsic value of the reflectivity, the differential reflectivity, and the copolar correlation coefficient at zero lag time are then determined. Application of this to a model convective rain cell shows that the use of simultaneous transmission and reception of linear vertical and linear horizontal polarization at S, C, and X bands provides accurate estimates of the intrinsic scattering properties of precipitation. The analysis of the bias on the radar observables due to the assumption of a medium of equioriented hydrometeors shows that all the observables with the exception of reflectivity can be severely affected.

* Current affiliation: Environnement Canada, Centre Météorologique Canadien, Dorval, Quebec, Canada.

Corresponding author address: Enrico Torlaschi, Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, Case postale 8888, Succursale Centre-Ville, Montréal, PQ H3C 3P8, Canada.

Save
  • Balakrishnan, N., and D. S. Zrnic, 1989: Correction of propagation effects at attenuating wavelengths in polarimetric radars. Preprints, 24th Conf. on Radar Meteorology, Tallahassee, FL, Amer. Meteor. Soc., 287–291.

  • ——, and ——, 1990: Use of polarization to characterize precipitation and discriminate large hail. J. Atmos. Sci.,47, 1525–1540.

    • Crossref
    • Export Citation
  • Bringi, V. N., and A. Hendry, 1990: Technology of polarization diversity radars for meteorology. Radar in Meteorology, D. Atlas, Ed., Amer. Meteor. Soc., 153–190.

    • Crossref
    • Export Citation
  • Chandrasekar, V., J. Hubbert, V. N. Bringi, and P. F. Meischener, 1994:Analysis and interpretation of dual polarized radar measurements at +45° and −45° linear polarization states. J. Atmos. Oceanic Technol.,11, 323–326.

    • Crossref
    • Export Citation
  • Doviak, J. R., and D. S. Zrnic, 1993: Doppler Radar and Weather Observations. Academic Press, 562 pp.

  • ——, ——, J. Carter, A. Ryzhkov, S. Torres, and A. Zahrai, 1998: NOAA/NSSL’s WSR-88D Radar for research and enhancement of operations: Polarimetric upgrades to improve rainfall measurements. National Severe Storms Laboratory Report, 110 pp. [Available from NOAA/National Severe Storms Laboratory, 1313 Halley Circle, Norman, OK 73069.].

  • English, M., B. Kochtubajda, F. D. Barlow, A. R. Holt, and R. McGuinness, 1991: Radar measurements of rainfall by differential propagation phase: A pilot experiment. Atmos.–Ocean,29, 357–380.

    • Crossref
    • Export Citation
  • Gingras, Y., 1997: Schèmes pour le radar météorologique à diversité de polarisation. M.S. thesis, Département des Sciences de la Terre, Université du Québec à Montréal, 137 pp.

  • ——, E. Torlaschi, and I. Zawadzki, 1997: A theoretical comparison between staggered and simultaneous H/V sampling in dual-polarization radar. Preprints, 28th Conf. on Radar Meteorology, Austin, TX, Amer. Meteor. Soc., 23–24.

  • Hendry, A., and Y. M. M. Antar, 1984: Precipitation particle identification with centimeter wavelength dual-polarization radars. Radio Sci.,19, 115–122.

    • Crossref
    • Export Citation
  • ——, ——, and G. C. McCormick, 1987: On the relationship between the degree of preferred orientation in precipitation and dual-polarization radar echo characteristics. Radio Sci.,22, 37–50.

    • Crossref
    • Export Citation
  • Holt, A. R., 1984: Some factors affecting the remote sensing of rain by polarization diversity radar in the 3- to 35-GHz frequency range. Radio Sci.,19, 1399–1412.

    • Crossref
    • Export Citation
  • ——, P. Joe, R. McGuinness, E. Torlaschi, T. Nichols, F. Bergwall, and D. A. Holland, 1994: Simultaneous polarization and Doppler observations of severe convective storms in central Alberta. Atmos. Res.,33, 37–56.

    • Crossref
    • Export Citation
  • Joe, P., and Coauthors, 1995: Recent progress in the operational forecasting of summer severe weather. Atmos.–Ocean,33, 249–302.

    • Crossref
    • Export Citation
  • Marshall, J. S., and W. M. Palmer, 1948: The distribution of raindrops with size. J. Meteor.,5, 165–166.

    • Crossref
    • Export Citation
  • McCormick, G. C., and A. Hendry, 1975: Principles for the radar determination of the polarization properties of precipitation. Radio Sci.,10, 421–434.

  • McGuinness, R., and A. R. Holt, 1989: The extraction of rain-rates from CDR data. Preprints, 24th Conf. on Radar Meteorology, Tallahassee, FL, Amer. Meteor. Soc., 338–341.

  • Oguchi, T., 1983: Electromagnetic wave propagation and scattering in rain and other hydrometeors. Proc. IEEE,71, 1029–1078.

    • Crossref
    • Export Citation
  • Pruppacher, H. R., and R. L. Pitter, 1971: A semi-empirical determination of the shape of cloud and rain drops. J. Atmos. Sci.,28, 86–94.

    • Crossref
    • Export Citation
  • Ryzhkov, A. V., and D. S. Zrnic, 1995: Comparison of dual-polarization radar estimators of rain. J. Atmos. Oceanic Technol.,12, 249–256.

    • Crossref
    • Export Citation
  • Sachidananda, M., and D. S. Zrnic, 1985: ZDR measurement considerations for a fast scan capability radar. Radio Sci.,20, 907–922.

    • Crossref
    • Export Citation
  • ——, and ——, 1989: Efficient processing of alternately polarized radar signals. J. Atmos. Oceanic Technol.,6, 173–181.

    • Crossref
    • Export Citation
  • Scarchilli, G., E. Gorgucci, V. Chandrasekar, and T. A. Seliga, 1993:Rainfall estimation using polarimetric techniques at C-band frequencies. J. Appl. Meteor.,32, 1150–1160.

    • Crossref
    • Export Citation
  • Schroth, A., M. Chandra, and P. Meischener, 1989: A C-band coherent polarimetric radar for propagation and cloud physics research. J. Atmos. Oceanic Technol.,6, 803–822.

    • Crossref
    • Export Citation
  • Seliga, T. A., and V. N. Bringi, 1976: Potential use of radar differential reflectivity measurements at orthogonal polarization for measuring precipitation. J. Appl. Meteor.,15, 69–76.

    • Crossref
    • Export Citation
  • Tan J., A. R. Holt, A. Hendry, and D. H. O. Bebbington, 1991: Extracting rainfall rates from X-band CDR radar data by using differential propagation phase shift. J. Atmos. Oceanic Technol.,8, 790–801.

  • Torlaschi, E., and B. Pettigrew, 1990: Propagation effects on reflectivity for circularly polarized S-band radars. J. Atmos. Oceanic Technol.,7, 114–117.

    • Crossref
    • Export Citation
  • ——, and A. R. Holt, 1993: Separation of propagation and backscattering effects in rain for circular polarization diversity S-band radars. J. Atmos. Oceanic Technol.,10, 465–477.

  • ——, and ——, 1998: A comparison of different polarization schemes for the radar sensing of precipitation. Radio Sci.,33, 1335–1352.

    • Crossref
    • Export Citation
  • ——, R. G. Humphries, and B. Barge, 1984: Circular polarization for precipitation measurement. Radio Sci.,19, 193–200.

    • Crossref
    • Export Citation
  • Watson, R. J., and E. Torlaschi, 1998: The effects of limited linear receiver dynamic range on the estimation of differential propagation phase. COST 75 Final Int. Seminar on Advanced Weather Radar Systems, Brussels, Belgium, Eur. Commiss., 12 pp.

  • Zahrai, A., and D. S. Zrnic, 1997: Implementation of polarimetric capability for the WSR-88D (NEXRAD) radar. Preprints, 28th Conf. on Radar Meteorology, Austin, TX, Amer. Meteor. Soc., 284–285.

  • Zrnic, D. S., 1996: Weather radar polarimetry—Trends toward operational applications. Bull Amer. Meteor. Soc.,77, 1529–1534.

    • Crossref
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 470 170 4
PDF Downloads 227 78 4