1. 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
- Author
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Chengfeng SHEN and Guoping LI
- Subjects
sichuan basin and its surrounding areas ,heavy precipitation ,gpm ,dual frequency spaceborne radar ,vertical structure of precipitation ,Meteorology. Climatology ,QC851-999 - 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 fluctuates 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 facilitates raindrops to collide and aggregate into large raindrops, and it is also easier to break the precipitation particles into small raindrops, which not only causes the occurrence probability of large raindrops(mass-weighted mean diameter, Dm≥2.6 mm) increases but also causes the distribution range of Dm widening; For heavy stratiform precipitation events, the occurrence probability of medium-diameter precipitation particles(1.4 mm≤Dm≤1.65 mm) below the freezing height over high mountains is greater than that over plains.(3) For heavy convective precipitation events, the 10 log10 of the particle number concentration (dBNw) high-frequency region over plains is more concentrated than those over mountains and high mountains, while the situation of heavy stratiform 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, Dm and dBNw are very close.For heavy convective precipitation events, the distribution range of the high-frequency area of Dm is highly consistent with the distribution range of the high-frequency area of radar reflectivity factor.Dm of heavy convective precipitation near the surface is larger than that of heavy stratiform precipitation, but dBNw of heavy convective precipitation is smaller than that of heavy stratiform precipitation.This study contributes to an in-depth understanding of the influence of topography on heavy precipitation by cloud microphysical process and vertical structure of precipitation.
- Published
- 2022
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