Based on NCEP 1°×1°daily reanalysis data and conventional surface observation data,the potential vortex theory was used to analyze a strong cold air activity process of Karamay during May 15-16,2019.The...Based on NCEP 1°×1°daily reanalysis data and conventional surface observation data,the potential vortex theory was used to analyze a strong cold air activity process of Karamay during May 15-16,2019.The results showed that the weather had obviously baroclinic characteristic.A strong cold tongue extended straight to Central Asia from the high latitude area,and the cold air was strong and deep.The driving effect of cold trough could accelerate it to move southward.The Aral Sea low vortex obstructed the warm air in the north in high latitude area,and the southwest air flow in the front of the vortex conducted to the transportation of water vapor to Central Asia.Compared with the climate average field of 1981-2010,the northwest flow at 500 hPa in May of 2019 was aggressive,which had frequently influenced Xinjiang by cold air from the north high latitude regions.The east flow of the bottom layer not only input cold air to Karamay,but also formed the windward slope effect with the terrain.Moreover,it increased the vertical wind shear and induced the upward movement.The center of high potential vorticity with high latitude fell southward,and the center of low potential vorticity in Central Asia moved eastward rapidly.They combined and then moved toward Xinjiang,which made the strong cold air erupt rapidly.When the right side of the moved axis of the high potential vorticity center and the strong west flow superposed over the Karamay area,the center of the strong rainfall area appeared 6 h later.展开更多
Taking a typical strong storm in Guizhou on April 5, 2017 for example, the diagnosis analysis used the water vapor cloud and the initial field of EC thin grid, including physical quantity, surface and upper air meteor...Taking a typical strong storm in Guizhou on April 5, 2017 for example, the diagnosis analysis used the water vapor cloud and the initial field of EC thin grid, including physical quantity, surface and upper air meteorological observation, as well as radar observation data. For the environment parameter analysis, small CAPE value tended to underestimate storm intensity on potential forecast stage, strong vertical wind shear revealed the strong dry cold air was the important intensity factors of the storm. The water vapor cloud map can be used to monitor the most important features, the dry zone, the wet zone and the boundary between them. When dry intrusion is found, it can be used as one of the bases for the development of heavy rain. Dry cold air intrusion on high-level was traced by water vapor images. And in this process, the analyses revealed the role of dry cold air’s influence on intensity of the storm.展开更多
选用1961—2019年中国京津冀地区气象观测站点日最低气温、NOAA月海表温度和NCEP/NCAR月500 hPa高度场,统计分析该地区冬季强冷空气日数变化特征及其与海表温度的关系,及Ni o3.4区海温影响强冷空气的太平洋—北美型(Pacific North Ameri...选用1961—2019年中国京津冀地区气象观测站点日最低气温、NOAA月海表温度和NCEP/NCAR月500 hPa高度场,统计分析该地区冬季强冷空气日数变化特征及其与海表温度的关系,及Ni o3.4区海温影响强冷空气的太平洋—北美型(Pacific North American pattern,PNA)遥相关机制。结果表明:京津冀地区冬季单站强冷空气年均发生日数为0.0~8.7 d,空间分布为西北向东南递减。京津冀地区冬季强冷空气日数同前期夏季、秋季和同期冬季海温的显著正相关区主要位于赤道中东太平洋,而西风漂流区和北大西洋东北部显著负相关区出现在前期秋季和同期冬季,赤道印度洋显著正相关仅在同期出现。京津冀地区冬季强冷空气日数异常受乌拉尔山高压脊、贝加尔湖低压、东亚中低纬度异常高压和东亚大槽等500 hPa高度场变化影响。同时,Nino3.4区海温异常通过PNA遥相关模式影响高度场变化,间接影响该地区的强冷空气日数。展开更多
文摘Based on NCEP 1°×1°daily reanalysis data and conventional surface observation data,the potential vortex theory was used to analyze a strong cold air activity process of Karamay during May 15-16,2019.The results showed that the weather had obviously baroclinic characteristic.A strong cold tongue extended straight to Central Asia from the high latitude area,and the cold air was strong and deep.The driving effect of cold trough could accelerate it to move southward.The Aral Sea low vortex obstructed the warm air in the north in high latitude area,and the southwest air flow in the front of the vortex conducted to the transportation of water vapor to Central Asia.Compared with the climate average field of 1981-2010,the northwest flow at 500 hPa in May of 2019 was aggressive,which had frequently influenced Xinjiang by cold air from the north high latitude regions.The east flow of the bottom layer not only input cold air to Karamay,but also formed the windward slope effect with the terrain.Moreover,it increased the vertical wind shear and induced the upward movement.The center of high potential vorticity with high latitude fell southward,and the center of low potential vorticity in Central Asia moved eastward rapidly.They combined and then moved toward Xinjiang,which made the strong cold air erupt rapidly.When the right side of the moved axis of the high potential vorticity center and the strong west flow superposed over the Karamay area,the center of the strong rainfall area appeared 6 h later.
文摘Taking a typical strong storm in Guizhou on April 5, 2017 for example, the diagnosis analysis used the water vapor cloud and the initial field of EC thin grid, including physical quantity, surface and upper air meteorological observation, as well as radar observation data. For the environment parameter analysis, small CAPE value tended to underestimate storm intensity on potential forecast stage, strong vertical wind shear revealed the strong dry cold air was the important intensity factors of the storm. The water vapor cloud map can be used to monitor the most important features, the dry zone, the wet zone and the boundary between them. When dry intrusion is found, it can be used as one of the bases for the development of heavy rain. Dry cold air intrusion on high-level was traced by water vapor images. And in this process, the analyses revealed the role of dry cold air’s influence on intensity of the storm.
文摘选用1961—2019年中国京津冀地区气象观测站点日最低气温、NOAA月海表温度和NCEP/NCAR月500 hPa高度场,统计分析该地区冬季强冷空气日数变化特征及其与海表温度的关系,及Ni o3.4区海温影响强冷空气的太平洋—北美型(Pacific North American pattern,PNA)遥相关机制。结果表明:京津冀地区冬季单站强冷空气年均发生日数为0.0~8.7 d,空间分布为西北向东南递减。京津冀地区冬季强冷空气日数同前期夏季、秋季和同期冬季海温的显著正相关区主要位于赤道中东太平洋,而西风漂流区和北大西洋东北部显著负相关区出现在前期秋季和同期冬季,赤道印度洋显著正相关仅在同期出现。京津冀地区冬季强冷空气日数异常受乌拉尔山高压脊、贝加尔湖低压、东亚中低纬度异常高压和东亚大槽等500 hPa高度场变化影响。同时,Nino3.4区海温异常通过PNA遥相关模式影响高度场变化,间接影响该地区的强冷空气日数。
