Rain retrieval from dual‐frequency radar Doppler spectra: validation and potential for a midlatitude precipitating case‐study

A recently developed technique retrieving the binned raindrop size distributions (DSDs) and air state parameters from ground-based Ka and W-band radars Doppler spectra profiles is improved and applied to a typical midlatitude rain event. The retrievals are thoroughly validated against DSD observations of a 2D video disdrometer and independent X-band observations. For this case-study, profiles of rain rate, R, mean volume diameter and concentration parameter are retrieved, with low bias and standard deviations. In light rain (0.1 < R < 1 mm h−1), the radar reflectivities must be calibrated with a collocated disdrometer which introduces random errors due to sampling mismatch between the two instruments. The best performances are obtained in moderate rain (1 < R < 20 mm h−1) where the retrieval is providing self-consistent estimates of the absolute calibration and of the attenuation caused by antenna or radome wetness for both radars.

[1]  C. Williams,et al.  Estimation of Rainfall Drop Size Distributions from Dual-Frequency Wind Profiler Spectra Using Deconvolution and a Nonlinear Least Squares Fitting Technique , 2002 .

[2]  E. Luke,et al.  Characterization of Vertical Velocity and Drop Size Distribution Parameters in Widespread Precipitation at ARM Facilities , 2012 .

[3]  Robert F. Cahalan,et al.  A Variational Method to Retrieve the Extinction Profile in Liquid Clouds Using Multiple-Field-of-View Lidar , 2012 .

[4]  G. Thompson,et al.  Sensitivity of a simulated midlatitude squall line to parameterization of raindrop breakup , 2012 .

[5]  Jimmy W. Voyles,et al.  The Arm Climate Research Facility: A Review of Structure and Capabilities , 2013 .

[6]  A. Illingworth,et al.  Differential Doppler Velocity: A Radar Parameter for Characterizing Hydrometeor Size Distributions , 1997 .

[7]  P. E. Johnston,et al.  Profiler Contributions to Tropical Rainfall Measuring Mission (TRMM) Ground Validation Field Campaigns , 2002 .

[8]  Christopher R. Williams,et al.  Reflectivity and Liquid Water Content Vertical Decomposition Diagrams to Diagnose Vertical Evolution of Raindrop Size Distributions , 2016 .

[9]  Sergey Y. Matrosov,et al.  Attenuation-Based Estimates of Rainfall Rates Aloft with Vertically Pointing Ka-Band Radars , 2005 .

[10]  S. Matrosov.  Characteristic Raindrop Size Retrievals from Measurements of Differences in Vertical Doppler Velocities at Ka- and W-Band Radar Frequencies , 2017 .

[11]  P. Rosenkranz.  Water vapor microwave continuum absorption: A comparison of measurements and models , 1998 .

[12]  Pavlos Kollias,et al.  Automated rain rate estimates using the Ka-band ARM zenith radar (KAZR) , 2014 .

[13]  Nicolas Gaussiat,et al.  Stratocumulus Liquid Water Content from Dual-Wavelength Radar , 1999 .

[14]  R. C. Srivastava,et al.  Doppler radar characteristics of precipitation at vertical incidence , 1973 .

[15]  Olivier P. Prat,et al.  The Impact of Raindrop Collisional Processes on the Polarimetric Radar Variables , 2014 .

[16]  Pavlos Kollias,et al.  G band atmospheric radars: new frontiers in cloud physics , 2014 .

[17]  Jason A. Milbrandt,et al.  Comparison of Two-Moment Bulk Microphysics Schemes in Idealized Supercell Thunderstorm Simulations , 2011 .

[18]  The effect of raindrop clustering on collision‐induced break‐up of raindrops , 2004 .

[19]  P. Joe,et al.  Snowfall Measurements by Proposed European GPM Mission , 2007 .

[20]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[21]  V. Chandrasekar,et al.  BAECC: a field campaign to elucidate the impact of Biogenic Aerosols on Clouds and Climate a field campaign to elucidate the impact of Biogenic Aerosols , 2018 .

[22]  Kenneth S. Gage,et al.  Drop-Size Distribution Characteristics in Tropical Mesoscale Convective Systems , 2000 .

[23]  E. Luke,et al.  Automated Retrievals of Precipitation Parameters Using Non-Rayleigh Scattering at 95 GHz , 2010 .

[24]  Pavlos Kollias,et al.  Why Mie? Accurate observations of vertical air velocities and raindrops using a cloud radar , 2002 .

[25]  Arthur Y. Hou,et al.  Estimation of Rain Intensity Spectra over the Continental United States Using Ground Radar-Gauge Measurements , 2012 .

[26]  Christopher R. Williams,et al.  Examining the correlations between drop size distribution parameters using data from two side-by-side 2D-video disdrometers , 2014 .

[27]  A. Illingworth,et al.  Absolute Calibration of 94/95-GHz Radars Using Rain , 2003 .

[28]  P. Kollias,et al.  Disentangling Mie and attenuation effects in rain using a Ka‐W dual‐wavelength Doppler spectral ratio technique , 2013 .

[29]  C. Williams,et al.  A Field Study of Reflectivity and Z–R Relations Using Vertically Pointing Radars and Disdrometers , 2009 .

[30]  Robert A. Black,et al.  The Concept of “Normalized” Distribution to Describe Raindrop Spectra: A Tool for Cloud Physics and Cloud Remote Sensing , 2001 .

[31]  Gerhard Peters,et al.  Profiles of Raindrop Size Distributions as Retrieved by Microrain Radars , 2005 .

[32]  Pavlos Kollias,et al.  First observations of triple‐frequency radar Doppler spectra in snowfall: Interpretation and applications , 2016 .

[33]  Alessandro Battaglia,et al.  Dual‐frequency radar Doppler spectral retrieval of rain drop size distributions and entangled dynamics variables , 2015 .

[34]  Roger Lhermitte,et al.  Attenuation and Scattering of Millimeter Wavelength Radiation by Clouds and Precipitation , 1990 .

[35]  Peter T. May,et al.  Using Dual-Polarized Radar and Dual-Frequency Profiler for DSD Characterization: A Case Study from Darwin, Australia , 2009 .

[36]  A. Hou,et al.  The Global Precipitation Measurement Mission , 2014 .

[37]  Jussi Leinonen,et al.  A Climatology of Disdrometer Measurements of Rainfall in Finland over Five Years with Implications for Global Radar Observations , 2012 .

[38]  Jeffrey A. Jones,et al.  An Initial Assessment of the Surface Reference Technique Applied to Data from the Dual-Frequency Precipitation Radar (DPR) on the GPM Satellite , 2015 .

[39]  E. Luke,et al.  Signal Postprocessing and Reflectivity Calibration of the Atmospheric Radiation Measurement Program 915-MHz Wind Profilers , 2013 .

[40]  Witold F. Krajewski,et al.  Two-dimensional video disdrometer: A description , 2002 .

[41]  Patrick Gatlin,et al.  Comparison of Raindrop Size Distribution Measurements by Collocated Disdrometers , 2013 .

[42]  Christopher R. Williams,et al.  An Intercomparison of Model Simulations and VPR Estimates of the Vertical Structure of Warm Stratiform Rainfall during TWP-ICE , 2008 .

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

[44]  E. Luke,et al.  On the unified estimation of turbulence eddy dissipation rate using Doppler cloud radars and lidars , 2016 .

[45]  R. C. Srivastava,et al.  An Analytical Solution for Raindrop Evaporation and Its Application to Radar Rainfall Measurements , 2001 .

[46]  Alexander V. Ryzhkov,et al.  The Impact of Evaporation on Polarimetric Characteristics of Rain: Theoretical Model and Practical Implications , 2009 .

[47]  G. Peters,et al.  Rain Attenuation of Radar Echoes Considering Finite-Range Resolution and Using Drop Size Distributions , 2010 .

[48]  C. Williams,et al.  Monitoring the Reflectivity Calibration of a Scanning Radar Using a Profiling Radar and a Disdrometer , 2005 .