Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region
The Sichuan-Tibet Region is a key area for the development of western China, where severe convective weather such as thunderstorm gales occur frequently. However, due to the complex terrains, synoptic systems, and the lack of meteorological observations, it is especially challenging to make accurate...
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Editorial Office of Journal of Applied Meteorological Science
2021-09-01
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| Series: | 应用气象学报 |
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| Online Access: | http://qikan.camscma.cn/en/article/doi/10.11898/1001-7313.20210505 |
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| author | Wang Hong Li Ying Wen Yongren |
| author_facet | Wang Hong Li Ying Wen Yongren |
| author_sort | Wang Hong |
| collection | DOAJ |
| description | The Sichuan-Tibet Region is a key area for the development of western China, where severe convective weather such as thunderstorm gales occur frequently. However, due to the complex terrains, synoptic systems, and the lack of meteorological observations, it is especially challenging to make accurate prediction. To better understand the mechanism of severe convective weather over the plateau, a rare severe convective event in the Sichuan-Tibet Region on 8 Sep 2016 is analyzed with weather reports, hourly and minutely surface observations, sounding data and Doppler weather radar data from China Meteorological Administration and ERA-Interim 0.5°×0.5° reanalysis data from European Centre for Medium-Range Weather Forecasts (ECMWF). The result shows that hourly rainfall of over 10 mm and hails of over 18 mm are observed at several weather stations, indicating a hybrid moist convective event. The meso-scale convective system (MCS) occurs near a shear line at low level with weak cold advection at 500 hPa. Large environmental convective available potential energy (CAPE), vertical wind shear, and the thick moist atmospheric layer are conductive to the formation of supercell. The initial convection is generated along a surface convergence line, with multiple γ meso-scale cells embedded in stratiform cloud in the north and cluster cells in the south. They move to the southeast, enter the favorable environment and merge with each other, enabling the cell on the south side to quickly develop into a supercell. When the supercell grows matured, the characteristic of front inflow gap, hook echoes and mesoscale cyclone at low levels are clear. The strong echo region tilts forward with height. There is significant overshooting top with the echo top height up to 15 km above ground in the upper troposphere, and obvious echo overhang capping bounded weak-echo region (BWER) in the middle layer. Mid-altitude radial convergence, weakening of updrafts and rapid drop of the reflectivity core indicate the occurrence of downbursts inside the storm. The cooling effect due to the entrainment of midlevel dry air is favorable to the growing of big hails and raindrops, and the formation of downdrafts. Moreover, the drag effect related to the rapid drop of heavy raindrops and hails, and the narrow tube effect of the canyon terrain, contribute to the formation of thunderstorm gales near the ground. |
| format | Article |
| id | doaj-art-a2c4e21cd4d845d28d46ad1c8fc58b7e |
| institution | OA Journals |
| issn | 1001-7313 |
| language | English |
| publishDate | 2021-09-01 |
| publisher | Editorial Office of Journal of Applied Meteorological Science |
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| series | 应用气象学报 |
| spelling | doaj-art-a2c4e21cd4d845d28d46ad1c8fc58b7e2025-08-20T02:18:55ZengEditorial Office of Journal of Applied Meteorological Science应用气象学报1001-73132021-09-0132556757910.11898/1001-7313.20210505yyqxxb-32-5-567Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet RegionWang Hong0Li Ying1Wen Yongren2State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081Chinese Academy of Meteorological Sciences, Beijing 100081The Sichuan-Tibet Region is a key area for the development of western China, where severe convective weather such as thunderstorm gales occur frequently. However, due to the complex terrains, synoptic systems, and the lack of meteorological observations, it is especially challenging to make accurate prediction. To better understand the mechanism of severe convective weather over the plateau, a rare severe convective event in the Sichuan-Tibet Region on 8 Sep 2016 is analyzed with weather reports, hourly and minutely surface observations, sounding data and Doppler weather radar data from China Meteorological Administration and ERA-Interim 0.5°×0.5° reanalysis data from European Centre for Medium-Range Weather Forecasts (ECMWF). The result shows that hourly rainfall of over 10 mm and hails of over 18 mm are observed at several weather stations, indicating a hybrid moist convective event. The meso-scale convective system (MCS) occurs near a shear line at low level with weak cold advection at 500 hPa. Large environmental convective available potential energy (CAPE), vertical wind shear, and the thick moist atmospheric layer are conductive to the formation of supercell. The initial convection is generated along a surface convergence line, with multiple γ meso-scale cells embedded in stratiform cloud in the north and cluster cells in the south. They move to the southeast, enter the favorable environment and merge with each other, enabling the cell on the south side to quickly develop into a supercell. When the supercell grows matured, the characteristic of front inflow gap, hook echoes and mesoscale cyclone at low levels are clear. The strong echo region tilts forward with height. There is significant overshooting top with the echo top height up to 15 km above ground in the upper troposphere, and obvious echo overhang capping bounded weak-echo region (BWER) in the middle layer. Mid-altitude radial convergence, weakening of updrafts and rapid drop of the reflectivity core indicate the occurrence of downbursts inside the storm. The cooling effect due to the entrainment of midlevel dry air is favorable to the growing of big hails and raindrops, and the formation of downdrafts. Moreover, the drag effect related to the rapid drop of heavy raindrops and hails, and the narrow tube effect of the canyon terrain, contribute to the formation of thunderstorm gales near the ground.http://qikan.camscma.cn/en/article/doi/10.11898/1001-7313.20210505thunderstorm galessupercell |
| spellingShingle | Wang Hong Li Ying Wen Yongren Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region 应用气象学报 thunderstorm gales supercell |
| title | Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region |
| title_full | Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region |
| title_fullStr | Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region |
| title_full_unstemmed | Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region |
| title_short | Observational Characteristics of A Hybrid Severe Convective Event in the Sichuan-Tibet Region |
| title_sort | observational characteristics of a hybrid severe convective event in the sichuan tibet region |
| topic | thunderstorm gales supercell |
| url | http://qikan.camscma.cn/en/article/doi/10.11898/1001-7313.20210505 |
| work_keys_str_mv | AT wanghong observationalcharacteristicsofahybridsevereconvectiveeventinthesichuantibetregion AT liying observationalcharacteristicsofahybridsevereconvectiveeventinthesichuantibetregion AT wenyongren observationalcharacteristicsofahybridsevereconvectiveeventinthesichuantibetregion |