Precision Evaluation of Micro Rain Radar Observation in Two Precipitation Events
MRR is a vertically pointing Micro Rain Radar which can measure vertical profiles of radar reflectivity and drop size distribution (DSD). It plays an important role in understanding precipitation microphysical structure and improving quantitative precipitation estimation. In this study, the observations from an Sband Doppler radar, a 2DVideoDisdrometer and a rain gauge during two summer precipitation events in Nanjing are used to assess the performance of MRR. The intercomparison analyses of these four instruments in stratiform and convective precipitation are also performed. The results show that, the vertical profile of reflectivity measured by MRR and Sband radar has a good agreement below 4 km with the mean difference less than 1 dB. Above 4 km, however, MRR tends to underestimate the reflectivity due to the precipitation attenuation. The difference of reflectivity between MRR and Sband radar increases with the height. Furthermore, MRR can accurately estimate the rain rate with the reflectivity below 35 dBz, but underestimate the rain rate with the reflectivity above 35 dBz. The rainfall estimation for stratiform clouds is more accurate than that for convective clouds. Especially, MRR exhibits good performance for the weak rainfall below 0.1 mm·h-1, which cannot be measured by rain gauge. Due to the inherent limitation of MRR and the precipitation attenuation, MRR shows high consistency with 2DVD for raindrops with size from 1 mm to 5 mm, but underestimates the concentration of drops larger than 5 mm and overestimates the concentration of drops smaller than 1 mm. Overall, MRR is an effective instrument for the precipitation measurements, especially suitable for quantitative estimation of stratiform.