Based on the conventional meteorological data and 4 times daily NCEP reanalysis data,the causes of rain changing snowstorm in Liaoning during February 12-13 of 2009 were discussed.The low-level jet conditions,temperat...Based on the conventional meteorological data and 4 times daily NCEP reanalysis data,the causes of rain changing snowstorm in Liaoning during February 12-13 of 2009 were discussed.The low-level jet conditions,temperature conditions and coupling mechanism of water vapor and dynamics of heavy snow were diagnosed and analyzed.The low-level jet provided abundant water vapor for this process.The convergence at low level,divergence in the upper troposphere and strong ascend movement provided dynamic conditions for the snowstorm.The wedging of cold air was the chief cause of rain changing snow.The strongprecipitation area corresponded to the moist potential vorticity well.展开更多
该文概述了卫星遥感积雪监测原理,介绍了积雪判识方法,对国家卫星气象中心已有的业务化极轨气象卫星冬季旬积雪监测算法和流程进行了改进。经过比对,设计了新的可见光太阳天顶角订正模式,针对NOAA-16／AVHRR3和FY-1D／MVISR重新确定了...该文概述了卫星遥感积雪监测原理,介绍了积雪判识方法,对国家卫星气象中心已有的业务化极轨气象卫星冬季旬积雪监测算法和流程进行了改进。经过比对,设计了新的可见光太阳天顶角订正模式,针对NOAA-16／AVHRR3和FY-1D／MVISR重新确定了积雪判识变量及相应的动态积雪检测阈值,提出了概率积雪判识方法,结合多光谱阈值法建立了概率结合阈值(Probability Combined with Threshold,PCT)的积雪判识方法,并以该算法为基础建立了新的业务化积雪动态遥感监测系统。同时,用新算法对部分历史产品重新做了处理,并简要分析了1996至2003年中国地区冬季积雪分布特征。展开更多
By using NCAR/NCEP daily reanalysis data and the precipitation data in Liaoning routine automatic station during July 14-16,2008,the regional rainstorm weather process in Liaoning was done the isentropic analysis. Acc...By using NCAR/NCEP daily reanalysis data and the precipitation data in Liaoning routine automatic station during July 14-16,2008,the regional rainstorm weather process in Liaoning was done the isentropic analysis. According to the variation characteristics of isobar,isocratic specific humidity line and wind field on the isentropic surface,the rainstorm landing zone was gained and compared with the analysis results of isobaric surface. The results showed that the warm wet transportation belt on 330 K isentropic surface provided the rich water vapor condition for the rainstorm generation,and the distribution of air-pressure and wind field on the isentropic surface favored to understand the movement of airflow. Compared with the analysis of isobaric surface,the analysis of isobaric surface could better directly judge the landing zone of precipitation,and the forecast effect was better than the analysis forecast results of isobaric surface.展开更多
In this paper,the analysis of two short periods of strong convection weather occurring in the northern part of Liaoning on August 8,2007 and July 16,2008 is made,which verifies that the two processes are typical sever...In this paper,the analysis of two short periods of strong convection weather occurring in the northern part of Liaoning on August 8,2007 and July 16,2008 is made,which verifies that the two processes are typical severe convective weather processes of cold vortex.They agree on location of occurrence,weather background and the characteristics of radar data.展开更多
文摘Based on the conventional meteorological data and 4 times daily NCEP reanalysis data,the causes of rain changing snowstorm in Liaoning during February 12-13 of 2009 were discussed.The low-level jet conditions,temperature conditions and coupling mechanism of water vapor and dynamics of heavy snow were diagnosed and analyzed.The low-level jet provided abundant water vapor for this process.The convergence at low level,divergence in the upper troposphere and strong ascend movement provided dynamic conditions for the snowstorm.The wedging of cold air was the chief cause of rain changing snow.The strongprecipitation area corresponded to the moist potential vorticity well.
文摘该文概述了卫星遥感积雪监测原理,介绍了积雪判识方法,对国家卫星气象中心已有的业务化极轨气象卫星冬季旬积雪监测算法和流程进行了改进。经过比对,设计了新的可见光太阳天顶角订正模式,针对NOAA-16／AVHRR3和FY-1D／MVISR重新确定了积雪判识变量及相应的动态积雪检测阈值,提出了概率积雪判识方法,结合多光谱阈值法建立了概率结合阈值(Probability Combined with Threshold,PCT)的积雪判识方法,并以该算法为基础建立了新的业务化积雪动态遥感监测系统。同时,用新算法对部分历史产品重新做了处理,并简要分析了1996至2003年中国地区冬季积雪分布特征。
文摘By using NCAR/NCEP daily reanalysis data and the precipitation data in Liaoning routine automatic station during July 14-16,2008,the regional rainstorm weather process in Liaoning was done the isentropic analysis. According to the variation characteristics of isobar,isocratic specific humidity line and wind field on the isentropic surface,the rainstorm landing zone was gained and compared with the analysis results of isobaric surface. The results showed that the warm wet transportation belt on 330 K isentropic surface provided the rich water vapor condition for the rainstorm generation,and the distribution of air-pressure and wind field on the isentropic surface favored to understand the movement of airflow. Compared with the analysis of isobaric surface,the analysis of isobaric surface could better directly judge the landing zone of precipitation,and the forecast effect was better than the analysis forecast results of isobaric surface.
基金Supported by Meteorological Observatory of Liaoning Province
文摘In this paper,the analysis of two short periods of strong convection weather occurring in the northern part of Liaoning on August 8,2007 and July 16,2008 is made,which verifies that the two processes are typical severe convective weather processes of cold vortex.They agree on location of occurrence,weather background and the characteristics of radar data.
