| AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR
OF SOUTH CHINA COASTAL AREAS |
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| 作者姓名： | 郑腾飞 于 鑫 黄 健 万齐林 刘显通 |
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| 摘 要： | On May 20 th 2007, a brief but severe downpour rainstorm occurred in the coastal areas of Maoming and Yangjiang with rainfall of 115 mm per hour. Data from NCEP/NCAR reanalysis with 1°×1° resolution, Doppler weather radar, conventional surface observations, high-altitude radiosonde and wind profiler radar were used to analyze characteristics and contributions of synoptic scale and mesoscale systems during this torrential rainstorm. The results showed that:(1) the storm was caused by a quasi-linear mesoscale convective system(MCS) and the slow-movement of this system was the primary trigger of the torrential downpour;(2) water vapor was abundant, nearly saturated and in steady state throughout the atmosphere before the storm; intrusion of the weak dry and cold air in the middle level and a striking "dry above and wet below " structure had increased the atmospheric instability;(3) low-level southwesterly airflow from a low pressure(trough) at the Beibu Gulf provided abundant water vapor at the onset of the rainstorm; a deep dry layer was formed by dry and cold air behind the high-level trough, which facilitated latent heat release;upper-level divergence and low-level convergence circulations also provided vertical uplift for warm and moist air at the lower level;(4) Topography only played a minor role as the MCS developed and strengthened over relatively flat coastal terrain. Low level density flow induced by convection triggered new convective cell generation at the leading edge of the convective system, thereby playing a key role in the change of temperature gradient at lower layers, and resulting in strengthening atmospheric instability.
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| 关 键 词： | south China coastal areas rainstorm in the warm sector synoptic scale systems mesoscale process |
| 修稿时间： | 2018/9/11 0:00:00 |
AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR
OF SOUTH CHINA COASTAL AREAS |
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| ZHENG Teng-fei,YU Xin,HUANG Jian,WAN Qi-lin and LIU Xian-tong.AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR
OF SOUTH CHINA COASTAL AREAS[J].Journal of Tropical Meteorology,2018,24(4):481-493. |
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| Authors: | ZHENG Teng-fei YU Xin HUANG Jian WAN Qi-lin and LIU Xian-tong |
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| Institution: | Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, CMA, Guangzhou 510080 China |
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| Abstract: | On May 20th 2007, a brief but severe downpour rainstorm occurred in the coastal areas of Maoming and Yangjiang with rainfall of 115mm per hour. Data from NCEP/NCAR reanalysis with 1°×1° resolution, Doppler weather radar, conventional surface observations, high-altitude radiosonde and wind profiler radar were used to analyze characteristics and contributions of synoptic scale and mesoscale systems during this torrential rainstorm. The results showed that: (1) the storm was caused by a quasi-linear mesoscale convective system (MCS) and the slow-movement of this system was the primary trigger of the torrential downpour; (2) water vapor was abundant, nearly saturated and in steady state throughout the atmosphere before the storm; intrusion of the weak dry and cold air in the middle level and a striking “dry above and wet below ” structure had increased the atmospheric instability; (3) low-level southwesterly airflow from a low pressure (trough) at the Beibu Gulf provided abundant water vapor at the onset of the rainstorm; a deep dry layer was formed by dry and cold air behind the high-level trough, which facilitated latent heat release; upper-level divergence and low-level convergence circulations also provided vertical uplift for warm and moist air at the lower level; (4) Topography only played a minor role as the MCS developed and strengthened over relatively flat coastal terrain. Low level density flow induced by convection triggered new convective cell generation at the leading edge of the convective system, thereby playing a key role in the change of temperature gradient at lower layers, and resulting in strengthening atmospheric instability. |
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| Keywords: | south China coastal areas rainstorm in the warm sector synoptic scale systems mesoscale process |
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