Intercomparison between 2DVD and MRR Datasets

Simultaneous measurements of the rain drop size distribution were made by a 2-dimensional video disdrometer (2DVD, Joanneum Research, Graz, Austria) and a MicroRain Radar-Pro (MRR-Pro, Metek, Elmshorn, Germany) deployed near Charleston, South Carolina, USA and horizontally separated by approximately 20 meters. The 2DVD data was post-processed to correct for spurious drop detection and incorrect assignment of effective sensor area, and the MRR-Pro spectral data was corrected to incorporate a height-dependent estimate of the ambient vertical wind. Surface 2DVD drop measurements were utilized to reconstruct an approximation of the drop size distribution aloft at different heights and times to compare to the inferred MRR-Pro drop spectrum and bulk rain parameters. Despite fundamentally different measurement principles and different sets of assumptions associated with the reconstruction of drop size distributions aloft, the agreement between the 2DVD and MRR-Pro data showed promise. The two data sets are further investigated in order to reveal possible features of boundary layer rain vertical variability, estimates of drop-drop collision rates, and near-surface rain microphysical phenomena.