Experiments in Rainfall Estimation with a Polarimetric Radar in a Subtropical Environment

Abstract A unique dataset consisting of high-resolution polarimetric radar measurements and dense rain gauge and disdrometer observations collected in east-central Florida during the summer of 1998 was examined. Comparison of the radar measurements and radar parameters computed from the disdrometer observations supported previous studies, which indicate that oscillating drops in the free atmosphere have more spherical apparent shapes in the mean than equilibrium shapes. Radar–disdrometer comparisons improved markedly when using an empirical axis ratio relation developed from observational studies and representing more spherical drop shapes. Fixed-form power-law rainfall estimators for radar reflectivity (ZH), specific differential phase (KDP), specific differential phase–differential reflectivity (KDP, ZDR), and radar reflectivity–differential reflectivity (ZH, ZDR) were then determined using the disdrometer observations. Relations were produced for both equilibrium shapes and the empirical axis ratios. P...

[1]  Jothiram Vivekanandan,et al.  A Comparison of Radar Reflectivity Estimates of Rainfall from Collocated Radars , 1999 .

[2]  H. R. Pruppacher,et al.  A wind tunnel investigation of the internal circulation and shape of water drops falling at terminal velocity in air , 1970 .

[3]  A. R. Jameson,et al.  Collisional Forcing of Raindrop Oscillations , 1983 .

[4]  Alexander V. Ryzhkov,et al.  Comparison of Dual-Polarization Radar Estimators of Rain , 1995 .

[5]  Karen Andsager,et al.  Laboratory Measurements of Axis Ratios for Large Raindrops , 1999 .

[6]  A. W. Green,et al.  An Approximation for the Shapes of Large Raindrops , 1975 .

[7]  Alexander V. Ryzhkov,et al.  Assessment of Rainfall Measurement That Uses Specific Differential Phase , 1996 .

[8]  Guifu Zhang,et al.  A method for estimating rain rate and drop size distribution from polarimetric radar measurements , 2001, IEEE Trans. Geosci. Remote. Sens..

[9]  A. Illingworth,et al.  Observations of oblate hail using dual polarization radar and implications for hail‐detection schemes , 1999 .

[10]  V. Chandrasekar,et al.  Raindrop axis ratios and size distributions in Florida rainshafts: an assessment of multiparameter radar algorithms , 1998, IEEE Trans. Geosci. Remote. Sens..

[11]  M. Sachidananda,et al.  Rain Rate Estimates from Differential Polarization Measurements , 1987 .

[12]  Eugenio Gorgucci,et al.  Specific Differential Phase Estimation in the Presence of Nonuniform Rainfall Medium along the Path , 1999 .

[13]  Eugenio Gorgucci,et al.  Radar and Surface Measurement of Rainfall during CaPE: 26 July 1991 Case Study , 1995 .

[14]  Peter T. May,et al.  Sensitivity of 5-cm Wavelength Polarimetric Radar Variables to Raindrop Axial Ratio and Drop Size Distribution , 2001 .

[15]  Witold F. Krajewski,et al.  Wind-Induced Error of Raindrop Size Distribution Measurement Using a Two-Dimensional Video Disdrometer , 2000 .

[16]  A. Ishimaru.  Electromagnetic Wave Propagation, Radiation, and Scattering , 1990 .

[17]  V. N. Bringi,et al.  Potential Use of Radar Differential Reflectivity Measurements at Orthogonal Polarizations for Measuring Precipitation , 1976 .

[18]  Rodney J. Kubesh,et al.  Laboratory Measurements of Small Raindrop Distortion. Part 2: Oscillation Frequencies and Modes , 1991 .

[19]  Alexander V. Ryzhkov,et al.  An Evaluation of Radar Rainfall Estimates from Specific Differential Phase , 2001 .

[20]  Eugenio Gorgucci,et al.  Practical Aspects of Radar Rainfall Estimation Using Specific Differential Propagation Phase , 2000 .

[21]  N. Balakrishnan,et al.  Estimation of Rain and Hail Rates in Mixed-Phase Precipitation , 1990 .

[22]  Boris Sevruk,et al.  Adjustment of tipping-bucket precipitation gauge measurements , 1996 .

[23]  K. Beard.  Oscillation models for predicting raindrop axis and backscatter ratios , 1984 .

[24]  V. Chandrasekar,et al.  Error Structure of Multiparameter Radar and Surface Measurements of Rainfall. Part III : Specific Differential Phase , 1990 .

[25]  V. N. Bringi,et al.  Rain-Rate Estimation in the Presence of Hail Using S-Band Specific Differential Phase and Other Radar Parameters , 1995 .

[26]  A Preliminary Study of Comparative Measurements of Rainfall Rate Using the Differential Reflectivity Radar Technique and a Raingage Network , 1981 .

[27]  A. R. Jameson.  A comparison of microwave techniques for measuring rainfall , 1991 .

[28]  Carlton W. Ulbrich,et al.  Assessment of the contribution of differential polarization to improved rainfall measurements , 1984 .

[29]  V. Bringi,et al.  Comparison of Dual-Polarization Radar Measurements of Rain with Ground-Based Disdrometer Measurements , 1982 .

[30]  R. Gunn,et al.  THE TERMINAL VELOCITY OF FALL FOR WATER DROPLETS IN STAGNANT AIR , 1949 .

[31]  V. Chandrasekar,et al.  Axis ratios and oscillations of raindrops , 1988 .

[32]  A. Ryzhkov,et al.  Precipitation observed in Oklahoma mesoscale convective systems with a polarimetric radar , 1994 .

[33]  H. Pruppacher,et al.  A Semi-Empirical Determination of the Shape of Cloud and Rain Drops , 1971 .

[34]  Alexander V. Ryzhkov,et al.  Beamwidth Effects on the Differential Phase Measurements of Rain , 1998 .

[35]  Koray Aydin,et al.  C-Band Dual-Polarization Radar Observables in Rain , 1992 .

[36]  Eugenio Gorgucci,et al.  Self-consistency of polarization diversity measurement of rainfall , 1996, IEEE Trans. Geosci. Remote. Sens..

[37]  Guifu Zhang,et al.  Effects of random inhomogeneity on radar measurements and rain rate estimation , 2002, IEEE Trans. Geosci. Remote. Sens..

[38]  J. W. F. Goddard,et al.  The ability of dual‐polarization radar (copolar linear) to predict rainfall rate and microwave attenuation , 1984 .

[39]  Alexander V. Ryzhkov,et al.  Advantages of Rain Measurements Using Specific Differential Phase , 1996 .

[40]  D. Yates,et al.  The Influence of Terrain on Rainfall Estimates from Radar Reflectivity and Specific Propagation Phase Observations , 1999 .

[41]  Polarimetrically Tuned R(Z) Relations and Comparison of Radar Rainfall Methods , 1997 .

[42]  Paul H. Herzegh,et al.  Observing Precipitation through Dual-Polarization Radar Measurements , 1992 .

[43]  H. Direskeneli,et al.  Disdrometer Measurements during an Intense Rainfall Event in Central Illinois: Implications for Differential Reflectivity Radar Observations , 1986 .

[44]  Alexander V. Ryzhkov,et al.  Precipitation and Attenuation Measurements at a 10-cm Wavelength , 1995 .

[45]  J. W. F. Goddard,et al.  Technique for calibration of meteorological radars using differential phase , 1994 .

[46]  K. Beard,et al.  A New Model for the Equilibrium Shape of Raindrops , 1987 .