Page 180 - 《高原气象》2022年第6期

6 期 沈程锋等：基于GPM资料的四川盆地及周边地区夏季地形降水垂直结构研究 1543

The Vertical Structure of Orographic Precipitation during Warm Season

in the Sichuan Basin and Its Surrounding Areas by Using GPM
Dual-frequency Spaceborne Precipitation Radar

1
SHEN Chengfeng ，LI Guoping 1，2
（1. School of Atmospheric Sciences，Chengdu University of Information Technology，Chengdu 610225，Sichuan，China；
2. Ministry of Education & Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters，
Nanjing University of Information Science & Technology，Nanjing 2 10044，Jiangsu，China）

Abstract：After dividing the Sichuan Basin and its surrounding areas into three types of terrain，including
plains，mountains（500~1500 m above sea level），and high mountains（1500~4000 m above sea level）using
ETOPO1 elevation data，this study statistics on convective and stratiform precipitation events over three types of
terrain using the Dual-frequency Precipitation Radar （DPR） onboard the Global Precipitation Measurement
（GPM）Core Observatory from May to September of 2014-2021 in order to analyze the vertical structure of
heavy convective and stratiform precipitation to contrast where the differences they are. The result shows that：
（1）The precipitation particles of the light convective precipitation over plains are most significantly affected by
evaporation in the near-surface layer that compared with other rain rate，which causes reflectivity factor fluctu‐
ates greatly and tends to weaken in surface layer. For heavy convective precipitation events，in addition，the
height of the high frequency center of the radar reflectivity factor increases with the increasing elevation.（2）For
heavy convective precipitation events，as the terrain rises，the strong updraft formed by the topography facili‐
tates raindrops to collide and aggregate into large raindrops，and it is also easier to break the precipitation parti‐
cles into small raindrops，which not only causes the occurrence probability of large raindrops（mass-weighted
mean diameter， D m ≥2. 6 mm）increases but also causes the distribution range of D m widening；For heavy strati‐

form precipitation events，the occurrence probability of medium-diameter precipitation particles（1. 4 mm≤D m ≤
1. 65 mm）below the freezing height over high mountains is greater than that over plains.（3）For heavy convec‐
tive precipitation events，the 10 log10 of the particle number concentration（dBN w ）high-frequency region over
plains is more concentrated than those over mountains and high mountains，while the situation of heavy strati‐
form precipitation events is just the opposite. In a few words，the precipitation particles at altitudes above 10 km
over high mountains have the characteristics as lower droplet number concentration and larger diameter compared
to plains.（4）The association among the radar reflectivity factor， D m and dBN w are very close. For heavy convec‐
tive precipitation events，the distribution range of the high-frequency area of D m is highly consistent with the dis‐
tribution range of the high-frequency area of radar reflectivity factor. D m of heavy convective precipitation near
the surface is larger than that of heavy stratiform precipitation，but dBN w of heavy convective precipitation is
smaller than that of heavy stratiform precipitation. This study contributes to an in-depth understanding of the in‐
fluence of topography on heavy precipitation by cloud microphysical process and vertical structure of precipita‐
tion.
Key words：Sichuan Basin and its surrounding areas；heavy precipitation；GPM；dual frequency spaceborne ra‐
dar；vertical structure of precipitation