Based on the conventional meteorological data and the NCEP/NCAR 1° × 1° reanalysis data and those related to mid-scale automatic station, satellite cloud picture and radar return, with the dynamic...Based on the conventional meteorological data and the NCEP/NCAR 1° × 1° reanalysis data and those related to mid-scale automatic station, satellite cloud picture and radar return, with the dynamic diagnosis analysis method, an analysis is made on the process of the convective rainstorm of quasi-stationary front triggered by the weak cold air on June 4-7, 2014, showing: 1) the process occurred in the event of convection of a stationary front triggered by the eastward moving south trough and the southward moving weak cold air from west under the background of circulation of two ridges and one trough at the Asian-European mid-high latitude and weakening and southeastward moving subtropical high;2) a system configuration that contributes to convective rainstorms formed in the event of the convergence of low-level moisture, upper-level divergence and the continuous vertical ascending motion after the 200 hPa upper-level jet stream moved westwards from east and the 850 hPa southwest jet stream intensified;3) after the intrusion by weak cold air of the meso-scale katallobaric area formed by the accumulated warm moist air of Guangxi before the intrusion, the warm moist air rose to trigger convection;convection cells developed and spread nearby the boundary between anallobaric area and katallobaric area, during which total 5 MCSs developed and each formed a rainstorm center at the part where the MCSs coincide;a meso-scale katallobaric area forms and develops 2 - 5 hours earlier than convection, so that it is also a warning of heavy rains.展开更多
采用北京常规气象资料和边界层资料,包括大气风廓线仪、L波段秒级探空雷达、大气成分探测数据、道面监测数据、微波辐射计数据和地面自动站观测资料,对2014年2月19日至27日北京地区一次罕见的持续性严重雾霾天气进行综合分析。将此次低...采用北京常规气象资料和边界层资料,包括大气风廓线仪、L波段秒级探空雷达、大气成分探测数据、道面监测数据、微波辐射计数据和地面自动站观测资料,对2014年2月19日至27日北京地区一次罕见的持续性严重雾霾天气进行综合分析。将此次低能见度事件划分为两个阶段,以雾为主的阶段和以霾为主的雾霾转换阶段。对雾阶段的形成、雾阶段向雾霾转化阶段的边界层特征变化进行了分析。结果表明:(1)即便在整层相对湿度显著降低的情况下,如果PM2.5浓度显著上升,能见度依然会继续降低。(2)干暖空气混合于雾层是雾阶段向雾霾混合阶段转换的重要条件。(3)4次北风活动中,必须同时满足3个条件:(a)存在北风;(b)北风造成了低层大气气温降低(700 h Pa、850 h Pa、925 h Pa);(c)冷空气到达地面。缺少任何一个条件,所谓的弱冷空气多扩散条件的改善将不存在,能见度不会升高、污染物浓度不会降低。(4)逆温层的消失会在一定程度而非根本上改善能见度并降低污染物浓度。(5)高浓度PM2.5气团对北京的侵入自南向北发生,监测站PM2.5峰值浓度自北向南逐渐出现,PM2.5的侵入为雾阶段向雾霾转换阶段做必要准备。展开更多
[Objective] The research aimed to analyze a strong convective weather process in Beihai in summer. [Method] By using Micaps conventional data and the single station site information of Beihai, radar data, a strong con...[Objective] The research aimed to analyze a strong convective weather process in Beihai in summer. [Method] By using Micaps conventional data and the single station site information of Beihai, radar data, a strong convective weather process in Beihai City in August, 2010 was analyzed. [Result] 850 and 700 hPa cyclonic low-pressure circulation in the north of Vietnam and Beibu Gulf coast was favorable for the transportation of Bengal Bay southwest airflow, which provided the sufficient water vapor condition for the strong precipitation. The interaction of weak cold air and southeast warm wet airflow was the main cause of the strong rainfall process. The falling zone of strong precipitation related to the water vapor convergence. The maintenance of water vapor flux divergence field in southeast-northwest direction was favorable for the duration of strong precipitation in the south of Guangxi. Before the strong precipitation, the positive and negative vorticity in the high and low levels in Beihai station both abruptly strengthened, which was very favorable for generating the convection. The vertical velocity in the strong precipitation process turned from the positive value at the beginning into the negative value as the height variation. The turning had the indicated and early-warning roles on the generation of strong convective weather. [Conclusion] The research provided the theory basis for the strong convective weather forecast in Guangxi coast in summer.展开更多
201323号台风"菲特"是建国以来登陆我国的最强秋季台风,给浙江省带来暴雨天气。利用NCEP再分析资料从天气形势、动力、热力等方面对此次暴雨的成因进行了分析,结果表明:1)此次强降水可以分为两个阶段:第一阶段主要由"菲...201323号台风"菲特"是建国以来登陆我国的最强秋季台风,给浙江省带来暴雨天气。利用NCEP再分析资料从天气形势、动力、热力等方面对此次暴雨的成因进行了分析,结果表明:1)此次强降水可以分为两个阶段:第一阶段主要由"菲特"本身的环流引起;第二阶段由"菲特"残留云系长时间维持及其与弱冷空气的相互作用引起,且弱冷空气对降水的增幅作用十分明显。2)第一阶段水汽主要由其本身的环流提供,由"菲特"南侧的偏南风低空急流和东侧的偏东风低空急流从南海和西太平洋输送水汽,第二阶段水汽主要由"丹娜丝"外围的偏东风急流从西太平洋输送水汽。3)弱冷空气的扩散使斜压性增强,并使斜压位能释放转化为动能,促使台风残留低压环流加剧,并在台风外围东偏南暖湿气流之间形成中尺度辐合带,为暴雨天气的产生提供了良好的动力条件。4)弱冷空气叠加在950 h Pa以下较强的暖平流之上,加剧了上冷下暖的不稳定层结,同时也使低层辐合加强,为暴雨区中尺度对流云团的发展提供了动力抬升机制。展开更多
文摘Based on the conventional meteorological data and the NCEP/NCAR 1° × 1° reanalysis data and those related to mid-scale automatic station, satellite cloud picture and radar return, with the dynamic diagnosis analysis method, an analysis is made on the process of the convective rainstorm of quasi-stationary front triggered by the weak cold air on June 4-7, 2014, showing: 1) the process occurred in the event of convection of a stationary front triggered by the eastward moving south trough and the southward moving weak cold air from west under the background of circulation of two ridges and one trough at the Asian-European mid-high latitude and weakening and southeastward moving subtropical high;2) a system configuration that contributes to convective rainstorms formed in the event of the convergence of low-level moisture, upper-level divergence and the continuous vertical ascending motion after the 200 hPa upper-level jet stream moved westwards from east and the 850 hPa southwest jet stream intensified;3) after the intrusion by weak cold air of the meso-scale katallobaric area formed by the accumulated warm moist air of Guangxi before the intrusion, the warm moist air rose to trigger convection;convection cells developed and spread nearby the boundary between anallobaric area and katallobaric area, during which total 5 MCSs developed and each formed a rainstorm center at the part where the MCSs coincide;a meso-scale katallobaric area forms and develops 2 - 5 hours earlier than convection, so that it is also a warning of heavy rains.
文摘采用北京常规气象资料和边界层资料,包括大气风廓线仪、L波段秒级探空雷达、大气成分探测数据、道面监测数据、微波辐射计数据和地面自动站观测资料,对2014年2月19日至27日北京地区一次罕见的持续性严重雾霾天气进行综合分析。将此次低能见度事件划分为两个阶段,以雾为主的阶段和以霾为主的雾霾转换阶段。对雾阶段的形成、雾阶段向雾霾转化阶段的边界层特征变化进行了分析。结果表明:(1)即便在整层相对湿度显著降低的情况下,如果PM2.5浓度显著上升,能见度依然会继续降低。(2)干暖空气混合于雾层是雾阶段向雾霾混合阶段转换的重要条件。(3)4次北风活动中,必须同时满足3个条件:(a)存在北风;(b)北风造成了低层大气气温降低(700 h Pa、850 h Pa、925 h Pa);(c)冷空气到达地面。缺少任何一个条件,所谓的弱冷空气多扩散条件的改善将不存在,能见度不会升高、污染物浓度不会降低。(4)逆温层的消失会在一定程度而非根本上改善能见度并降低污染物浓度。(5)高浓度PM2.5气团对北京的侵入自南向北发生,监测站PM2.5峰值浓度自北向南逐渐出现,PM2.5的侵入为雾阶段向雾霾转换阶段做必要准备。
文摘[Objective] The research aimed to analyze a strong convective weather process in Beihai in summer. [Method] By using Micaps conventional data and the single station site information of Beihai, radar data, a strong convective weather process in Beihai City in August, 2010 was analyzed. [Result] 850 and 700 hPa cyclonic low-pressure circulation in the north of Vietnam and Beibu Gulf coast was favorable for the transportation of Bengal Bay southwest airflow, which provided the sufficient water vapor condition for the strong precipitation. The interaction of weak cold air and southeast warm wet airflow was the main cause of the strong rainfall process. The falling zone of strong precipitation related to the water vapor convergence. The maintenance of water vapor flux divergence field in southeast-northwest direction was favorable for the duration of strong precipitation in the south of Guangxi. Before the strong precipitation, the positive and negative vorticity in the high and low levels in Beihai station both abruptly strengthened, which was very favorable for generating the convection. The vertical velocity in the strong precipitation process turned from the positive value at the beginning into the negative value as the height variation. The turning had the indicated and early-warning roles on the generation of strong convective weather. [Conclusion] The research provided the theory basis for the strong convective weather forecast in Guangxi coast in summer.
文摘201323号台风"菲特"是建国以来登陆我国的最强秋季台风,给浙江省带来暴雨天气。利用NCEP再分析资料从天气形势、动力、热力等方面对此次暴雨的成因进行了分析,结果表明:1)此次强降水可以分为两个阶段:第一阶段主要由"菲特"本身的环流引起;第二阶段由"菲特"残留云系长时间维持及其与弱冷空气的相互作用引起,且弱冷空气对降水的增幅作用十分明显。2)第一阶段水汽主要由其本身的环流提供,由"菲特"南侧的偏南风低空急流和东侧的偏东风低空急流从南海和西太平洋输送水汽,第二阶段水汽主要由"丹娜丝"外围的偏东风急流从西太平洋输送水汽。3)弱冷空气的扩散使斜压性增强,并使斜压位能释放转化为动能,促使台风残留低压环流加剧,并在台风外围东偏南暖湿气流之间形成中尺度辐合带,为暴雨天气的产生提供了良好的动力条件。4)弱冷空气叠加在950 h Pa以下较强的暖平流之上,加剧了上冷下暖的不稳定层结,同时也使低层辐合加强,为暴雨区中尺度对流云团的发展提供了动力抬升机制。
