Raindrop size distributions and vertical air motions as inferred from zenith-pointing Doppler radar with the RONSARD system


  • D. Hauser,

  • P. Amayenc


This paper deals with results of raindrop size distributions and vertical air motions aloft within a cold front rainband, as inferred from vertical incidence Doppler spectra gathered with one radar of the RONSARD system. These results are obtained by using a new method recently proposed by the authors, assuming exponentially shaped raindrop size distributions. Comparison of the radar results with in situ measurements of raindrop size distributions aboard an aircraft indicates that the method provides satisfying estimates of the precipitating water content and of the median volume diameter of raindrops, though the values of the raindrop size distribution parameters N0 or Λ, deduced from the two techniques, are found to be significantly different. It is also found that the proposed method produces values of the deduced parameters with high time and space variability. Owing to this variability, the rainfall bulk parameters are found accurately connected only by means of three-parameter relationships. These characteristics are similar to those already depicted within another stratiform precipitation by using the same approach.