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Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China
Remote Sensing ( IF 5 ) Pub Date : 2022-06-28 , DOI: 10.3390/rs14133110
Yiliang Pu, Sheng Hu, Yali Luo, Xiantong Liu, Lihua Hu, Langming Ye, Huiqi Li, Feng Xia, Lingyu Gao

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.

中文翻译:

华南沿海极端暖区降雨事件的多尺度视角

2017年6月22日,华南西部沿海地区发生极端暖区降雨事件,最大每小时和12小时累计降雨量分别为189.4和464.8毫米,打破当地历史记录。多源观测被用来揭示导致极端降雨的多尺度过程。结果表明,海洋边界层急流(BLJ)与内陆天气低空急流(LLJ)相结合,在近地表空气升空冷凝水平极低的极端潮湿环境的形成中发挥了重要作用。在有利的对流前条件下,对流在中尺度辐合线处开始,在晚上地形抬升的帮助下。在夜间,暴雨发展并由准静止的中尺度流出边界维持,不断提升由增强的 BLJ 输送的温暖潮湿的空气。在产生极端降雨率时,风暴对流相对较弱,40 dBZ 的回波顶部几乎达不到 6 公里。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。由增强的 BLJ 输送的潮湿空气。在产生极端降雨率时,风暴对流相对较弱,40 dBZ 的回波顶部几乎达不到 6 公里。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。由增强的 BLJ 输送的潮湿空气。在产生极端降雨率时,风暴对流相对较弱,40 dBZ 的回波顶部几乎达不到 6 公里。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。在产生极端降雨率时,风暴对流相对较弱,40 dBZ 的回波顶部几乎达不到 6 公里。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。在产生极端降雨率时,风暴对流相对较弱,40 dBZ 的回波顶部几乎达不到 6 公里。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。此次极端降雨主要是由暖雨微物理过程产生的,主要是由于潮湿的环境和深厚的暖云层促进了云的凝结生长和碰撞聚结,也减少了降雨蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。也减少了雨水蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。也减少了雨水蒸发。随着风暴的演变,雨滴浓度从初始阶段迅速增加,并一直保持在高位,直到减弱阶段,但平均雨滴大小变化不大。极端降雨的特点是风暴期间雨滴浓度最高,平均雨滴大小略大于海上状态。
更新日期:2022-06-29
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