[Objective]The research aimed to study influence of the 850 hPa WPSH abnormality on rainfall in Jianghuai basin in early summer.[Method]Based on NCEP/NCAR 2.5°×2.5° analysis data,by using composite anal...[Objective]The research aimed to study influence of the 850 hPa WPSH abnormality on rainfall in Jianghuai basin in early summer.[Method]Based on NCEP/NCAR 2.5°×2.5° analysis data,by using composite analysis,correlation analysis,etc.,circulation and rainfall abnormalities were analyzed.Subtropical index related to geopotential height field,zonal wind field,precipitation rate,vertical velocity field and so on.Influence of the 850 hPa WPSH abnormality in early summer on rainfall in Jianghuai basin was discussed.[Result]850 hPa WPSH abnormality in early summer had important influence on rainfall in Jianghuai basin.When WPSH area was small in early summer,and ridge point was by east and north,there was no blocking high in Sea of Okhotsk area at 500 hPa height field,and pathway of the cold air at high latitude was by north.Low-pressure disturbance in plum rain frontal zone weakened,and East Asian summer monsoon circulation strengthened.Cold air in Jianghuai basin was weak,which caused less precipitation in Jianghuai basin.When WPSH area was big in early summer,and ridge point was by west and south,it was controlled by blocking high in Sea of Okhotsk area at 500 hPa height field.Low-pressure disturbance in plum rain frontal zone strengthened,and East Asian summer monsoon circulation weakened.Cold air in Jianghuai basin was strong,which caused more precipitation in Jianghuai basin.[Conclusion]The research played indicative role in precipitation abnormality in Jianghuai basin.展开更多
[Objective] The aim was to comparatively analyze two local heavy rainstroms in northwestern Shandong Province, China. [Method] Based on the observation data from automatic weather station, sounding data and NCEP reana...[Objective] The aim was to comparatively analyze two local heavy rainstroms in northwestern Shandong Province, China. [Method] Based on the observation data from automatic weather station, sounding data and NCEP reanalysis data, two local heavy rainstorms at night on July 18 and August 9 in 2010 in northwestern Shandong was comparatively analyzed from the aspects of circulation situation, influence system and physical field, and the internal structure and possible formation mechanism of local heavy rain in Shandong were discussed further. [Result] The two rainstorms occurred in the forepart of southwest air in front of 500 hPa trough, and there was stronger atmospheric baroclinicity in the front zone near 850 hPa. The two rainstorms were affected by southwest warm and humid airflow at low level and shear line at 850 hPa; rainstorm often appeared in intensive area behind θse high-energy tongue, and rainstorm area corresponded with the area with high vertical speed well. From the differences, during the first rainstorm, there was obvious southwest low level jet and shear line at 700 hPa, and the area with high precipitation was located in the south of warm shear line at 700 hPa; during the latter rainstorm, there was no obvious southwest low level jet and shear line, and the area with high precipitation was located in the region between two high pressures. [Conclusion] The study could provide valuable thinking for the forecast of this kind of rainstorm in the future.展开更多
文摘[Objective]The research aimed to study influence of the 850 hPa WPSH abnormality on rainfall in Jianghuai basin in early summer.[Method]Based on NCEP/NCAR 2.5°×2.5° analysis data,by using composite analysis,correlation analysis,etc.,circulation and rainfall abnormalities were analyzed.Subtropical index related to geopotential height field,zonal wind field,precipitation rate,vertical velocity field and so on.Influence of the 850 hPa WPSH abnormality in early summer on rainfall in Jianghuai basin was discussed.[Result]850 hPa WPSH abnormality in early summer had important influence on rainfall in Jianghuai basin.When WPSH area was small in early summer,and ridge point was by east and north,there was no blocking high in Sea of Okhotsk area at 500 hPa height field,and pathway of the cold air at high latitude was by north.Low-pressure disturbance in plum rain frontal zone weakened,and East Asian summer monsoon circulation strengthened.Cold air in Jianghuai basin was weak,which caused less precipitation in Jianghuai basin.When WPSH area was big in early summer,and ridge point was by west and south,it was controlled by blocking high in Sea of Okhotsk area at 500 hPa height field.Low-pressure disturbance in plum rain frontal zone strengthened,and East Asian summer monsoon circulation weakened.Cold air in Jianghuai basin was strong,which caused more precipitation in Jianghuai basin.[Conclusion]The research played indicative role in precipitation abnormality in Jianghuai basin.
文摘[Objective] The aim was to comparatively analyze two local heavy rainstroms in northwestern Shandong Province, China. [Method] Based on the observation data from automatic weather station, sounding data and NCEP reanalysis data, two local heavy rainstorms at night on July 18 and August 9 in 2010 in northwestern Shandong was comparatively analyzed from the aspects of circulation situation, influence system and physical field, and the internal structure and possible formation mechanism of local heavy rain in Shandong were discussed further. [Result] The two rainstorms occurred in the forepart of southwest air in front of 500 hPa trough, and there was stronger atmospheric baroclinicity in the front zone near 850 hPa. The two rainstorms were affected by southwest warm and humid airflow at low level and shear line at 850 hPa; rainstorm often appeared in intensive area behind θse high-energy tongue, and rainstorm area corresponded with the area with high vertical speed well. From the differences, during the first rainstorm, there was obvious southwest low level jet and shear line at 700 hPa, and the area with high precipitation was located in the south of warm shear line at 700 hPa; during the latter rainstorm, there was no obvious southwest low level jet and shear line, and the area with high precipitation was located in the region between two high pressures. [Conclusion] The study could provide valuable thinking for the forecast of this kind of rainstorm in the future.
