ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 43 Issue 12 > 2017,43(12):1507-1516. DOI:10.7519/j.issn.1000-0526.2017.12.006 Prev Next
Comparative Analysis on Mesoscale Characteristics of Two Local ShortTime Severe Rainstorm Processes in Chengde
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Abstract:
On 17 June and 15 July 2014, two continuous local shorttime severe rainstorms occurred in Chengde as a result of cold vortex. The hourly rainfalls were 39.6 and 66.1 mm·h-1 respectively and the maximum 10 min rainfalls were 15 and 18 mm correspondingly. Based on conventional observation data, 5-10 min automatic weather station data, Doppler radar data, satellite images and NCEP reanalysis data, the mesoscale characteristics of the two shorttime severe rainstorms are analyzed in this paper. The minute precipitation observation reveals that in the 17 June rainstorm process, 10 min rainfall showed a double peak type distribution as time going on, lasting about half an hour. In the 15 July rainstorm process, it showed a single peak type, which lasted less than 1 h. Both of the two local heavy rains were generated with the upper cold vortex circulation, and their triggering system is the ground mesoscale convergence center (convergence line). The precipitation peak was associated with southeast wind or the increased wind speed. The 6 m·s-1 southeast winds were favorable for the heavy rains. Satellite data show that the direct influence system of the rainstorm on 17 June 2014 was the mesoβ scale convective system. The heavy precipitation was corresponding to the low area of TBB. The severe convective system on 15 July 2014 performed as the mesoγ scale, corresponding to the large gradient area of TBB. The rainstorm on 17 June 2014 corresponded to the merge enhancement of convective cell echoes, which had a horizontal scale of near 20 km, lasting about half an hour with the echo intensity of 65 dBz. The rainstorm on 15 July 2014 was shown that a number of convective cell echoes passed through the urban area of Chengde in order, due to the “train effect”, and the convective cell echoes had a number of horizontal scales of less than 5 km, living less than 1 h with echo intensity 55 dBz. In two precipitation processes, the occurrence time of inverse wind area was corresponding to that of the shorttime strong rainfall, the duration of inverse wind area was longer, and the rainfall intensity is also stronger.
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P458
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