Observational Study Of Raindrop Size Distribution Characteristics In Shanxi

Raindrop size distribution is an important part of the physical process in cloud and precipitation.It is important to study the physical characteristics of precipitation,improve the technological of rainfall estimation by radar and the cloud physical parametric numerical model. Based on the raindrop spectrum observation data by the OTT Parsivel laser precipitation particle spectrometer at six observation point in Shanxi province from 2010 to 2012,the physical characteristics of convective and stratiform precipitation and the precipitation mechanism of different terrain and different areas are discussed.The primary conclusions are as follows:(1)The rainfall intensity,the generalized intercept parameter(Nw) and mass-weighted mean diameter(Dm) of raindrops are greater in mountain area than flat area.No matter in mountain area or in flat area,the mean raindrop size distribution of convective and stratiform precipitation shows unimodal distribution,whose peak diameter were 0.94mm and 0.56 mm,respectively.The Gamma distribution of average spectra is fitted better.The shape(μ)-slope(λ) relationship of the Gamma distribution of convective rain in flat and mountain area is X=0.0154μ2+0.682μ+1.962 and λ=0.0162μ2+0.710μ+1.840.(2)The radar reflectivity (Z)-rain rate (R), Nw-R and Dm-R relationship are different.The Nw-R and Dm-R and Z-R relationship of stratiform and convective in flat area are Nw=4273R0.25,Nw=4857R0.26,Dm=1.12R0.25,Dm=0.95R0.22,Z=240R1.33, Z=208R1.45.The Nw-R and Dm-R and Z-R relationship of stratiform and convective in mountain area are Nw=4266R0.24,Nw=4437R0.28,Dm=1.10R0.13,Dm=1.10R0.18, Z=215R131,Z=199R1.41.(3)Characteristics of convective and stratiform raindrop size distribution of Shanxi province are studied using the OTT Parsivel laser precipitation particle spectrometer. The results show that the microphysical characteristics of convective precipitation is greater than stratiform precipitation. In the convective precipitation, the correlation of number concentration, rainfall intensity and liquid water content is good. Particle diameter in 1-2mm has the largest contribution to the rain intensity.The raindrop size distribution of convective and stratiform precipitation shows unimodal distribution and the spectra of convective precipitation is wider than stratiform.The Gamma distribution of average spectra is fitted better.