A study of microphysical properties within a precipitation system using wind profiler spectra

This study investigates microphysical properties from wind profiler Doppler spectra observed within a precipitation system that produced high rainfall rates up to 40 mm hr −1 near the southern coast of the Korean Peninsula on 25∼26 June 2010. A 1290-MHz wind profiler located in the National Center for Intensive Observation of Severe Weather at Boseong, Korea, observed a widespread stratiform region and short-lived convective cells from 1850 UTC 25 to 0200 UTC 26 June 2010. By using a spectral model applied to observed profiler spectra, rainfall parameters and raindrop size distributions were retrieved below a melting layer during this period. Three representative periods during precipitation were selected based on intensities of bright band and characteristics in vertical profiles of radar reflectivity and Doppler velocity. During a brief convective period (∼30 min), radar reflectivity tended to be proportional to vertical air motion (positive upward), suggesting that updrafts up to ∼3 m s −1 over a large vertical extent through the melting layer probably contributed to increasing rainfall rates at the surface. In reflectivityrainfall rate distributions, large drop spectra (high reflectivity) were analyzed within downdrafts and small drop spectra (low reflectivity) within updrafts, similar to the large and small drop spectra but found in stratiform and convective regions, respectively, in previous studies. This indicates that the degree of spread between reflectivity and rainfall rate may be strongly dependent on positive and negative magnitudes of vertical air motion. For three categories of vertical air motion (i.e., updrafts, neutral, and downdrafts), physical relations between the retrieved rainfall parameters were examined.