ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 47 Issue 12 > 2021,47(12):1469-1483. DOI:10.7519/j.issn.1000-0526.2021.12.004 Prev Next
Spatio-Temporal Distribution and Environmental Parameters of Short-Time Severe Precipitation in the Chengde Mountains in Summer
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Abstract:
146 short-time severe precipitation cases in summer (JJA) were selected to analyze the distribution characteristics of short-time severe precipitation in Chengde from 2008 to 2017 based on the multiple data of automatic weather station, meteorological satellite, Doppler radar and NCEP reanalysis. The results show that the synoptic circulation patterns controlling severe precipitation in the Chengde Montains can be divided into the cold vortex type (45%), westerly trough type (34%) and edge of the western Pacific subtropical high (WPSH) type (21%). The short-time severe rainfall in June mostly occurs under the background of cold vortex circulations, with scattered rain falling areas. The dominant circulation pattern in the early-mid July is the westerly trough type but turns to be the edge of WPSH type after the late July. The severe precipitation under both the westerly trough type and the edge of WPSH type are generally distributed on the windward slope of Yanshan Mountain in the southern edge of Chengde. Differing from the traditional rainy season in North China, which is influenced by the position of subtropical high, the concentrated period of the short-term severe precipitation in Chengde is from late June to late July, and the peak appears when the cold vortex and the westerly trough circulations take action together. Mesoscale convective systems which are responsible for short-time severe precipitation move in Chengde mainly through southwest (northeastern Beijing) and northwest (Inner Mongolia) channels. In addition, a considerable number of convective storms are born locally in Chengde. The short-time severe precipitation in Chengde are often along with less water vapor and poor transportation compared with that in conventional rainy season. The water vapor content of cold vortex type is only 8 g·kg-1 at 850 hPa. The median of the area averaged atmospheric precipitable water (PW) is 33 mm in the Chengde Mountains and is only 29 mm under the cold vortex circulation. Even if the median of PW under the edge of WPSH type gets to 38 mm, it is still 15 mm lower than that in the south plain areas. The short-time severe precipitation often occurrs in extremely unstable stratification. The medians of temperature difference between 850 hPa and 500 hPa of cold vortex type and the westerly trough type are 28.6℃ and 27.9℃ respectively, while the others are below 25℃ in most of areas (including mountainous areas) of China.
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