[ Objective] The research aimed to analyze a local snowstorm weather process which happened in Beijing, Tianjin and Hebei during I - 4 January, 2010. [ Method] Based on routine meteorological observation data and NCEP...[ Objective] The research aimed to analyze a local snowstorm weather process which happened in Beijing, Tianjin and Hebei during I - 4 January, 2010. [ Method] Based on routine meteorological observation data and NCEP/NCAR 2.5° ×2.5° grid data （four times every day）, a lo- cal snowstorm weather process which happened in Beijing, Tianjin and Hebei during 1 -4 January, 2010 was carried out diagnostic analysis by using composite analysis method. [Result] Circumfluence on the ground and strong cold advection in the rear of upper trough were the main weath- er system of the snowfall. The deep thick wet layer and strong water vapor convergence provided sufficient water vapor for snowfall. The divergence field of low-level convergence and high^level divergence, dynamic coupling effect of vorticity provided favorable dynamic condition upwardly for the occurrence of strong snowfall. The steep dense area of Oso, low temperature at the ground layer and inversion temperature at the high layer provided certain energy condition for the development of snowfall weather. [ Conclusion] The research provided theoretical basis for snowfall forecast in future.展开更多
[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP an...[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of continuous rainy process were revealed.On the base,the influences of configuration of circulation fields and difference of physical quantity fields at high and low layers on range and intensity of precipitation were analyzed.[Result] According to the circulation situation and influence system,the continuous rainy process could be divided into four stages:July 22-24,from July 27 to August 1,August 4-8 and August 9-14.Moreover,it was respectively affected by northeast low vortex,cold and warm air,high-level low trough,typhoon and periphery of subtropical high at four stages.The maintenance of big specific humidity zone provided sufficient water vapor condition for the continuous rainy weather.The rainstorm appeared in dense zone of specific humidity line,where the specific humidity >13 g/kg in the humidity front zone.A temperature trough maintained at 850 hPa.The cold air which continued to diffuse and go south was main reason of the abnormally low temperature during the continuous rainy period.Moreover,it provided ascending motion condition for precipitation maintenance.[Conclusion] The research provided references for actual forecast of continuous rainy weather.展开更多
In early 2022,two snowfalls of different magnitudes occurred in southern Jiangsu and Anhui,which had different impacts on the operation of Nanjing Airport.Based on NCEP reanalysis data and the WRF3.9 model,the weather...In early 2022,two snowfalls of different magnitudes occurred in southern Jiangsu and Anhui,which had different impacts on the operation of Nanjing Airport.Based on NCEP reanalysis data and the WRF3.9 model,the weather condition and the physical quantity fields of two different situations were mainly compared and analyzed.The results show that the snowstorm occurred in the left front of the low-level jet stream and in the wind speed convergence area of the 700 h Pa shear line.The reasonable configuration of the convergence area of the water vapor flux divergence and the rising motion field can be regarded as an important reason for the occurrence of the snowstorm.Through the comparative analysis of these two snowfalls of different magnitudes,the focus of the short-term forecast of heavy snowfall at Nanjing Airport was preliminarily drawn:the 0℃line at 700 h Pa basically pressed southward to the south of 31°N,and the 0℃line at 850 h Pa pressed southward to the south of 30°N.Surface temperature was≤0℃,and temperature at 925-800 h Pa was≤-3 or-4℃;temperature at 700 h Pa was<0℃,and there was temperature inversion in the middle and lower troposphere.In the model forecast output field,the proportion of the mixing ratio of frozen precipitation in the near-surface atmosphere to the mixing ratio of water vapor that can condense into precipitation is very important,and can be used to determine the evolution of rain and snow boundaries and sleet areas or the south of rain and snow transition zone and precipitation phase.展开更多
文摘[ Objective] The research aimed to analyze a local snowstorm weather process which happened in Beijing, Tianjin and Hebei during I - 4 January, 2010. [ Method] Based on routine meteorological observation data and NCEP/NCAR 2.5° ×2.5° grid data （four times every day）, a lo- cal snowstorm weather process which happened in Beijing, Tianjin and Hebei during 1 -4 January, 2010 was carried out diagnostic analysis by using composite analysis method. [Result] Circumfluence on the ground and strong cold advection in the rear of upper trough were the main weath- er system of the snowfall. The deep thick wet layer and strong water vapor convergence provided sufficient water vapor for snowfall. The divergence field of low-level convergence and high^level divergence, dynamic coupling effect of vorticity provided favorable dynamic condition upwardly for the occurrence of strong snowfall. The steep dense area of Oso, low temperature at the ground layer and inversion temperature at the high layer provided certain energy condition for the development of snowfall weather. [ Conclusion] The research provided theoretical basis for snowfall forecast in future.
文摘[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of continuous rainy process were revealed.On the base,the influences of configuration of circulation fields and difference of physical quantity fields at high and low layers on range and intensity of precipitation were analyzed.[Result] According to the circulation situation and influence system,the continuous rainy process could be divided into four stages:July 22-24,from July 27 to August 1,August 4-8 and August 9-14.Moreover,it was respectively affected by northeast low vortex,cold and warm air,high-level low trough,typhoon and periphery of subtropical high at four stages.The maintenance of big specific humidity zone provided sufficient water vapor condition for the continuous rainy weather.The rainstorm appeared in dense zone of specific humidity line,where the specific humidity >13 g/kg in the humidity front zone.A temperature trough maintained at 850 hPa.The cold air which continued to diffuse and go south was main reason of the abnormally low temperature during the continuous rainy period.Moreover,it provided ascending motion condition for precipitation maintenance.[Conclusion] The research provided references for actual forecast of continuous rainy weather.
文摘In early 2022,two snowfalls of different magnitudes occurred in southern Jiangsu and Anhui,which had different impacts on the operation of Nanjing Airport.Based on NCEP reanalysis data and the WRF3.9 model,the weather condition and the physical quantity fields of two different situations were mainly compared and analyzed.The results show that the snowstorm occurred in the left front of the low-level jet stream and in the wind speed convergence area of the 700 h Pa shear line.The reasonable configuration of the convergence area of the water vapor flux divergence and the rising motion field can be regarded as an important reason for the occurrence of the snowstorm.Through the comparative analysis of these two snowfalls of different magnitudes,the focus of the short-term forecast of heavy snowfall at Nanjing Airport was preliminarily drawn:the 0℃line at 700 h Pa basically pressed southward to the south of 31°N,and the 0℃line at 850 h Pa pressed southward to the south of 30°N.Surface temperature was≤0℃,and temperature at 925-800 h Pa was≤-3 or-4℃;temperature at 700 h Pa was<0℃,and there was temperature inversion in the middle and lower troposphere.In the model forecast output field,the proportion of the mixing ratio of frozen precipitation in the near-surface atmosphere to the mixing ratio of water vapor that can condense into precipitation is very important,and can be used to determine the evolution of rain and snow boundaries and sleet areas or the south of rain and snow transition zone and precipitation phase.
