资源环境科技发展态势分析平台

In this paper, the statistical properties of summer and winter precipitation over the northern China plain are investigated by using a two-dimensional video disdrometer (2DVD) and a micro-rain radar (MRR). The properties of summer precipitation presented herein are bulk properties (radar reflectivity, reflectivity-weighted fall velocity, liquid water content, and rainfall rate), raindrop fall velocity, axis ratio, and particle size distribution. Well correlations can be found among the diurnal cycles of radar reflectivity, liquid water content, and rainfall rate, whereas reflectivity-weighted fall velocity is poorly related to other bulk properties. The vertical profiles exhibit that radar reflectivity for stratiform rain is increasing with the altitude decreasing, in contrast, liquid water content and rainfall rate are reducing during the falling. These facts are useful for the radar-based rainfall rate retrieval algorithm. Axis ratio measurements are, for the first time, obtained and analyzed in northern China, which are particularly important for improving microphysical scheme in the climate models. In the constraint gamma model, the is mu - Lambda relation is adapted to the particle size distribution of stratiform rain, while the normalized gamma distributions for convective rain are separated to maritime-like and continental categories following the orientations and mechanisms of the storms. A new bulk-property-based algorithm is developed for the classification of convective and stratiform precipitation. For winter precipitation, radar reflectivity and snowfall rate for aggregates are calculated from the disdrometer data. The relationship of radar reflectivity and snowfall rate is obtained and validated with MRR data. The characteristics of summer and winter precipitation will be used to improve the microphysical scheme and evaluate the representation of precipitation in the climate models.