Use of a Radar Simulator on the Output Fields from a Numerical Mesoscale Model to Analyze X-Band Rain Estimators

E-P. Zahiri Institut de Recherche pour le Développement, Laboratoire d’étude des Transferts en Hydrologie et Environnement, Grenoble, France

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M. Gosset Institut de Recherche pour le Développement, Laboratoire d’étude des Transferts en Hydrologie et Environnement, Grenoble, France

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J-P. Lafore Centre Nationale de Recherches Météorologiques, Toulouse, France

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V. Gouget Centre Nationale de Recherches Météorologiques, Toulouse, France

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Abstract

A full radar simulator, which works with the 3D output fields from a numerical mesoscale model, has been developed. This simulator uses a T-matrix code to calculate synthetic radar measurements, accounts for both backscattering and propagation effects, and includes polarimetric variables. The tool is modular to allow several options in the derivation of the synthetic radar variables. A measurement uncertainty can be taken into account on both the simulated reflectivities and the differential phase shift. A scheme can also be switched on to allow for the gate-to-gate variability of the rain drops size distribution or, also, their oblateness. This work was done in the framework of the installation in West Africa of a polarimetric X-band radar for the observation of tropical rain. Accordingly, the first objective pursued with this simulation setup is a detailed analysis of X-band polarimetric rain retrieval algorithms. Two retrieval schemes, a simple RKDP formula and a profiler that uses both reflectivity and ϕDP, are tested. For that purpose the simulator is run on a model case study of an African squall line, then the two schemes are used to retrieve the rain rates from the synthetic radar variables and compare them to the original. The scores of the schemes are discussed and compared. The authors analyze the sensitivity of the results to the measurement uncertainty and also to several aspects of drop size distribution and drop shape variability.

Corresponding author address: Marielle Gosset, I.R.D.–Cotonou, 08 B.P. 841, Aéroport, Bénin. Email: marielle.gosset@ird.fr

Abstract

A full radar simulator, which works with the 3D output fields from a numerical mesoscale model, has been developed. This simulator uses a T-matrix code to calculate synthetic radar measurements, accounts for both backscattering and propagation effects, and includes polarimetric variables. The tool is modular to allow several options in the derivation of the synthetic radar variables. A measurement uncertainty can be taken into account on both the simulated reflectivities and the differential phase shift. A scheme can also be switched on to allow for the gate-to-gate variability of the rain drops size distribution or, also, their oblateness. This work was done in the framework of the installation in West Africa of a polarimetric X-band radar for the observation of tropical rain. Accordingly, the first objective pursued with this simulation setup is a detailed analysis of X-band polarimetric rain retrieval algorithms. Two retrieval schemes, a simple RKDP formula and a profiler that uses both reflectivity and ϕDP, are tested. For that purpose the simulator is run on a model case study of an African squall line, then the two schemes are used to retrieve the rain rates from the synthetic radar variables and compare them to the original. The scores of the schemes are discussed and compared. The authors analyze the sensitivity of the results to the measurement uncertainty and also to several aspects of drop size distribution and drop shape variability.

Corresponding author address: Marielle Gosset, I.R.D.–Cotonou, 08 B.P. 841, Aéroport, Bénin. Email: marielle.gosset@ird.fr

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  • Anagnostou, E. N., Anagnostou M. N. , Krajewski W. F. , Kruger A. , and Miriovsky B. , 2004: High-resolution rainfall estimation from X-band polarimetric radar measurements. J. Hydrometeor., 5 , 110128.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Andsager, K., Beard K. V. , and Laird N. F. , 1999: Laboratory measurements of axis ratios for large raindrops. J. Atmos. Sci., 56 , 26732683.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berne, A., and Uijlenhoet R. , 2005: A stochastic model of range profiles of raindrop size distributions: Application to radar attenuation correction. Geophys. Res. Lett., 32 .L10803, doi:10.1029/2004GL021899.

    • Search Google Scholar
    • Export Citation
  • Brandes, E. A., Ryzhkov A. V. , and Zrnić D. S. , 2001: An evaluation of radar rainfall estimates from specific differential phase. J. Atmos. Oceanic Technol., 18 , 363375.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bringi, V. N., and Chandrasekar V. , 2001: Polarimetric Doppler Weather Radar: Principles and Applications. Cambridge University Press, 636 pp.

    • Search Google Scholar
    • Export Citation
  • Bringi, V. N., Chandrasekar V. , Balakrishnan N. , and Zrnić D. S. , 1990: An examination of propagation effects in rainfall on radar measurements at microwave frequencies. J. Atmos. Oceanic Technol., 7 , 829840.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Carey, L. D., Rutledge S. A. , Ahijevych D. A. , and Keenan T. D. , 2000: Correcting propagation effects in C-band polarimetric radar observations of tropical convection using differential propagation phase. J. Appl. Meteor., 39 , 14051433.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Caumont, O., and Coauthors, 2005: A radar observation operator for high-resolution nonhydrostatic numerical weather prediction. J. Atmos. Oceanic Technol., 22 , 14051433.

    • Search Google Scholar
    • Export Citation
  • Cazenave, F., Gosset M. , and Dossougoin J. , 2006: Xport, a compact radar for hydrological application. Proc. Fourth European Conf. on Radar in Meteorology and Hydrology (ERAD 2006), Barcelona, Spain, Copernicus Group, P2.4. [Available online at http://www.grahi.upc.es/ERAD2006/proceedingsMask/00027.pdf.].

  • Delrieu, G., Caoudal S. , and Creutin J. D. , 1997: Feasability of using mountain return for the correction of ground-based X-band weather radar data. J. Atmos. Oceanic Technol., 14 , 368385.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Diongue, A., Lafore J-P. , Redelsperger J-L. , and Roca R. , 2002: Numerical study of a Sahelian synoptic weather system: Initiation and mature stages of convection and its interactions with the large-scale dynamics. Quart. J. Roy. Meteor. Soc., 128 , 18991927.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fabry, F., Austin G. , and Tees D. , 1992: The accuracy of rainfall estimates by radar as a function of range. Quart. J. Roy. Meteor. Soc., 118 , 435453.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Goddard, J. W. F., Morgan K. L. , Illingworth A. J. , and Sauvageot H. , 1995: Dual wavelength polarization measurements in precipitation using the CAMRA and Rabelais radars. Preprints, 27th Conf. on Radar Meteorology, Vail, CO, Amer. Meteor. Soc., 196–198.

  • Gorgucci, E., Scarchilli G. , Chandrasekar V. , and Bringi V. N. , 2000: Measurement of mean raindrop shape from polarimetric radar observations. J. Atmos. Sci., 57 , 34063413.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gorgucci, E., Scarchilli G. , Chandrasekar V. , and Bringi V. N. , 2001: Rainfall estimation from polarimetric radar measurements: Composite algorithms immune to variability in raindrop shape–size relation. J. Atmos. Oceanic Technol., 18 , 17731786.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gosset, M., 2004: Effect of nonuniform beam filling on the propagation of radar signals at X-band frequencies. Part II: Examination of differential phase shift. J. Atmos. Oceanic Technol., 21 , 358367.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gosset, M., and Zawadzki I. , 2001: Effect of nonuniform beam filling on the propagation of the radar signal at X-band frequencies. Part I: Changes in the k(Z) relationship. J. Atmos. Oceanic Technol., 18 , 11131126.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Goutorbe, J-P., and Coauthors, 1994: HAPEX-Sahel: A large-scale study of land–atmosphere interactions in the semi-arid tropics. Ann. Geophys., 12 , 5364.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Haase, G., and Crewell S. , 2000: Simulation of radar reflectivities using a mesoscale weather forecast model. Water Resour. Res., 38 , 22212231.

    • Search Google Scholar
    • Export Citation
  • Hitschfeld, W., and Bordan J. , 1954: Errors inherent in the radar measurement of rainfall at attenuating wavelengths. J. Meteor., 11 , 5867.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Illingworth, A. J., and Blackman T. M. , 2002: The need to represent raindrop size spectra as normalized gamma distributions for interpretation of polarization radar observations. J. Appl. Meteor., 41 , 286297.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lafore, J. P., and Coauthors, 1998: The Meso-NH Atmospheric Simulation System. Part I: Adiabatic formulation and control simulations. Ann. Geophys., 16 , 90108.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marzoug, M., and Amayenc P. , 1991: Improved range-profiling algorithm of rainfall rate from a spaceborne radar with path-integrated attenuation constraint. IEEE Trans. Geosci. Remote Sens., 29 , 584592.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Matrosov, S. Y., Kropfli R. A. , Reinking R. F. , and Martner B. E. , 1999: Prospects for measuring rainfall using propagation differential phase in X- and Ka-radar bands. J. Appl. Meteor., 38 , 766776.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Matrosov, S. Y., Clark K. A. , Martner B. E. , and Tokay A. , 2002: X-band polarimetric radar measurements of rainfall. J. Appl. Meteor., 41 , 941952.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Matrosov, S. Y., Kingsmill D. E. , Martner B. E. , and Ralph F. M. , 2005: The utility of X-band polarimetric radar for quantitative estimates of rainfall parameters. J. Hydrometeor., 6 , 248262.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Miriovsky, B. J., and Coauthors, 2004: An experimental study of small-scale variability of radar reflectivity using disdrometer observations. J. Appl. Meteor., 43 , 106118.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mishchenko, M. I., and Travis L. D. , 1998: Capabilities and limitations of a current FORTRAN implementation of the T-matrix method for randomly oriented, rotationally symmetric scatterers. J. Quant. Spectrosc. Radiat. Transfer, 60 , 309324.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Park, S-G., Bringi V. N. , Chandrasekar V. , Maki M. , and Iwanami K. , 2005a: Correction of radar reflectivity and differential reflectivity for rain attenuation at X band. Part I: Theoretical and empirical basis. J. Atmos. Oceanic Technol., 22 , 16211632.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Park, S-G., Maki M. , Iwanami K. , Bringi V. N. , and Chandrasekar V. , 2005b: Correction of radar reflectivity and differential reflectivity for rain attenuation at X band. Part II: Evaluation and application. J. Atmos. Oceanic Technol., 22 , 16331655.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pellarin, T., Delrieu G. , Saulnier G-M. , Andrieu H. , Vignal B. , and Creutin J-D. , 2002: Hydrologic visibility of weather radar systems operating in mountainous regions: Case study for the Ardèche catchment (France). J. Hydrometeor., 3 , 539555.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rahimi, A. R., Holt A. R. , Upton G. J. G. , and Cummings R. J. , 2003: Use of dual-frequency microwave links for measuring path-averaged rainfall. J. Geophys. Res., 108 .4467, doi:10.1029/2002JD003202.

    • Search Google Scholar
    • Export Citation
  • Redelsperger, J-L., and Coauthors, 2006: AMMA, une étude multidisciplinaire de la Mousson Ouest-Africaine. Météorologie, 54 , 2232.

    • Search Google Scholar
    • Export Citation
  • Ryzhkov, A. V., and Zrnić D. , 1998: Beamwidth effects on the differential phase measurements of rain. J. Atmos. Oceanic Technol., 15 , 624634.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sachidananda, M., and Zrnić D. , 1987: Rain rate estimates from differential polarization measurements. J. Atmos. Oceanic Technol., 4 , 588598.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sánchez-Diezma, R., Zawadzki I. , and Sempere-Torres D. , 2000: Identification of the bright band through the analysis of volumetric radar data. J. Geophys. Res., 105D , 22252236.

    • Search Google Scholar
    • Export Citation
  • Sauvageot, H., 1996: Polarimetric radar at attenuated wavelengths as a hydrological sensor. J. Atmos. Oceanic Technol., 13 , 630637.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Smyth, T. J., and Illingworth A. J. , 1998: Correction for attenuation of radar reflectivity using polarization data. Quart. J. Roy. Meteor. Soc., 124 , 23932415.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Testud, J., Le Bouar E. , Obligis E. , and Ali-Mehenni M. , 2000: The rain profiling algorithm applied to polarimetric weather radar. J. Atmos. Oceanic Technol., 17 , 332356.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Testud, J., Oury S. , Black R. A. , Amayenc P. , and Dou X. , 2001: The concept of normalized distribution to describe raindrop spectra: A tool for cloud physics and cloud remote sensing. J. Appl. Meteor., 40 , 11181140.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Uijlenhoet, R., Steiner M. , and Smith J. A. , 2003: Variability of raindrop size distributions in a squall line and implications for radar rainfall estimation. J. Hydrometeor., 4 , 4361.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Waldvogel, A., 1974: The N0 jump of raindrop spectra. J. Atmos. Sci., 31 , 10671078.

  • Wu, B., Verlinde J. , and Sun J. , 2000: Dynamical and microphysical retrievals from Doppler radar observations of a deep convective cloud. J. Atmos. Sci., 57 , 262283.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Xiao, Q., Kuo Y-H. , Sun J. , Lee W-C. , Barker D. M. , and Lim E. , 2004: Assimilation of Doppler radar observations and its impacts on forecasting of the landfalling typhoon Rusa (2002). Proc. Third European Conf. on Radar in Meteorology and Hydrology (ERAD3), Visby, Sweden, European Geosciences Union, 178–182.

  • Zahiri, E-P., 2007: Cycle de l’eau des systemes convectifs ouest-africain: Preparation à l’exploitation des mesures radar Xport dans AMMA par simulations. Ph.D. dissertation, Université Paul Sabatier, 256 pp.

  • Zawadzki, I., 1984: Factors affecting the precision of radar measurements of rain. Preprints, 22nd Conf. on Radar Meteorology, Zurich, Switzerland, Amer. Meteor. Soc., 251–256.

  • Zrnić, D. S., Keenan T. D. , Carey L. D. , and May P. , 2000: Sensitivity analysis of polarimetric variables at a 5-cm wavelength in rain. J. Appl. Meteor., 39 , 15141526.

    • Crossref
    • Search Google Scholar
    • Export Citation
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