Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China
Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China
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DOI：
10.3390/rs14133110
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Yiliang Pu;Sheng Hu;Yali Luo;Xiantong Liu;L. Hu;Langming Ye;Huiqi Li;Feng Xia;Lingyu Gao-Lin
中科院分区：
文献类型：
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作者：
Yiliang Pu;Sheng Hu;Yali Luo;Xiantong Liu;L. Hu;Langming Ye;Huiqi Li;Feng Xia;Lingyu Gao-Lin
2017年6月22日，华南西部沿海地区出现极端暖区降雨过程，最大小时和12小时累计降雨量分别为189. 4和464. 8毫米，打破当地历史纪录。多尺度观测被用来揭示多尺度过程的极端降水。结果表明，海洋边界层急流（BLJ）与内陆天气低空急流（LLJ）的耦合，对形成近地面低抬升凝结的极端湿润环境起了重要作用。在有利的对流前条件下，对流在中尺度辐合线上初始化，并在晚上得到地形抬升的帮助。在夜间，暴雨的发展和维持准静止的中尺度流出边界，不断提升暖湿空气由增强BLJ输送。在产生极端降水率时，风暴具有相对较弱的对流，40 dBZ回波顶很难达到6 km。极端降水主要是由暖雨微物理过程产生的，主要原因是潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞合并，减少了降水蒸发。随着风暴的发展，雨滴浓度从初始阶段开始迅速增加，并一直维持到减弱阶段，但平均雨滴尺寸变化不大。这场极端降雨的特点是在风暴的一生中雨滴的浓度最高，雨滴的平均大小略大于海洋政权。
On 22 June 2017, an extreme warm-sector rainfall event hit the western coastal area of South China, with maximum hourly and 12-h rainfall accumulations of 189.4 and 464.8 mm, respectively, which broke local historical records. Multisource observations were used to reveal multiscale processes contributing to the extreme rainfall. The results showed that a marine boundary layer jet (BLJ) coupled with a synoptic low-level jet (LLJ) inland played an important role in the formation of an extremely humid environment with a very low lifting condensation level of near-surface air. Under the favorable pre-convective conditions, convection was initialized at a mesoscale convergence line, aided by topographic lifting in the evening. During the nocturnal hours, the rainstorm developed and was maintained by a quasi-stationary mesoscale outflow boundary, which continuously lifted warm, moist air transported by the enhanced BLJ. When producing the extreme rainfall rates, the storm possessed relatively weak convection, with the 40 dBZ echo top hardly reaching 6 km. The extreme rainfall was produced mainly by the warm rain microphysical processes, mainly because the humid environment and the deep warm cloud layer facilitated the clouds’ condensational growth and collision–coalescence, and also reduced rain evaporation. As the storm evolved, the raindrop concentration increased rapidly from its initial stage and remained high until its weakening stage, but the mean raindrop size changed little. The extreme rain was characterized by the highest concentration of raindrops during the storm’s lifetime with a mean size of raindrops slightly larger than the maritime regime.