ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 42 Issue 2 > 2016,42(2):144-155. DOI:10.7519/j.issn.1000-0526.2016.02.002 Prev Next
Characteristics of ShortTime Severe Rainfall Events Based on Weather Flow and Key Environmental Parameters in Pearl River Delta
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Abstract:
In order to understand the environmental characteristics of shorttime severe rainfall event (hourly rainfall amount ≥50 mm) in Pearl River Delta, we researched the weather flow, Tlnp chart patterns and key physical parameters of 68 shorttime intense rain event for nearly 7 years (2007-2013) by using automatic weather station data, sounding data, satellite data in the Pearl River Delta region. The results showed that such severe rainfalls in Pearl River Delta are characterized by, first, the weather flow patterns, which include typhoon type, southwest monsoon type, Beibu Gulf low pressure type, cold shear line type and tropical cloud type. Different types have different frequencies in different seasons. Secondly, temperature profiles and wet adiabat are very close in Tlnp in most of the shorttime severe rain events, and the water vapor content are rich in the whole layer. Thirdly, the features of the key parameters of the severe rainfalls are that mainly the value of T850-T500 is small, usually 21-23℃ with a weak unstable stratification, higher ground dew point and PW. CAPE values are more moderate, mostly less than 1500 J·kg-1. CIN and vertical wind shear of 0-6 km are relatively weak, and lowlevel jets appear in most cases. The key conditions for most of the shorttime severe rainfall process are not the highaltitude cold air intrusion, but the warm air transport from low level. Although small CAPE value limits updraft, the cloud base of specific humidity is high. If combining the configuration method of flow pattern (type), the key environmental parameters, the range of parameters to set appropriate threshold according to the box whisker plots, we can provide valuable reference to rebuild the forecast method of shorttime severe rainfall in the Pearl River Delta region.
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