In this study,regional rainstorm events (RREs) in northeastern China associated with the activity of the Northeastern China Cold Vortex (NCCV) were investigated on a medium-range time scale.The RREs occurring in north...In this study,regional rainstorm events (RREs) in northeastern China associated with the activity of the Northeastern China Cold Vortex (NCCV) were investigated on a medium-range time scale.The RREs occurring in northeastern China could be categorized into three groups according to the distribution of heavy rainfall.The largest cluster is characterized by the rainstorm events that occur on the northwestern side of the Changbai Mountains along a southwest-northeast axis.These events occur most frequently during the post-meiyu period.The authors place particular emphasis on the RREs that belong to the largest cluster and are closely associated with the activity of the NCCV.These RREs were preconditioned by the transportation of substantial amounts of water vapor to which the anomalous western Pacific subtropical high (WPSH) contributed.The attendant anomalous WPSH was primarily driven by the anomalous transient eddy feedback forcing the nearby East Asian jet.The development of the NCCV circulation was concurrent with the RREs and acted as their primary causative factor.A perspective based on low-frequency dynamics indicates that Rossby wave packets emanated from the blocking-type circulation over northeastern Asia led to the development of the NCCV activity.展开更多
[Objective] The aim was to study the prediction of summer rainstorm induced by southwest vortex.[Method] Based on 2.5°×2.5° re-analysis data in four time points a day from June to August during 1971-200...[Objective] The aim was to study the prediction of summer rainstorm induced by southwest vortex.[Method] Based on 2.5°×2.5° re-analysis data in four time points a day from June to August during 1971-2008 at 700 hPa in northern hemisphere provided by NECP,rainstorm and southwest vortex from June to August in Guizhou Province were studied systematically,and the forecast data of rainstorm induced by southest vortex was obtained.[Result] Southwest vortex was one of major systems influencing rainstorm in flood season(from June to August),especially in June and July;the occurrence of this kind of rainstorm was closely related to the moving path of southwest vortex,activity of cold air,environmental flow field at 500 hPa,shear line at 850 hPa,southwest jet,position of subtropical high ridge,water vapour conditions,vorticity field,etc.On the basis of factual data,objective forecast system was established and verified by means of similar method and physical diagnosis.The results showed that it was rational to choose upper trough,southwest vortex,conditions of vertical movement,southwest jet,water vapour conditions,etc.as forecast factors;when the center of southwest vortex was located in major key area(100°-105° E,25°-35° N),and secondary key area(105°-108° E,25°-35° N),regional rainstorm occurred most easily,especially in major key area with high frequency of rainstorm.[Conclusion] The study could provide references for the improvement of prediction level of rainstorm induced by southwest vortex,disaster prevention and reduction.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant No.40975033)the National Key Technologies R&D Program of China(Grant No.2009BAC51B02)
文摘In this study,regional rainstorm events (RREs) in northeastern China associated with the activity of the Northeastern China Cold Vortex (NCCV) were investigated on a medium-range time scale.The RREs occurring in northeastern China could be categorized into three groups according to the distribution of heavy rainfall.The largest cluster is characterized by the rainstorm events that occur on the northwestern side of the Changbai Mountains along a southwest-northeast axis.These events occur most frequently during the post-meiyu period.The authors place particular emphasis on the RREs that belong to the largest cluster and are closely associated with the activity of the NCCV.These RREs were preconditioned by the transportation of substantial amounts of water vapor to which the anomalous western Pacific subtropical high (WPSH) contributed.The attendant anomalous WPSH was primarily driven by the anomalous transient eddy feedback forcing the nearby East Asian jet.The development of the NCCV circulation was concurrent with the RREs and acted as their primary causative factor.A perspective based on low-frequency dynamics indicates that Rossby wave packets emanated from the blocking-type circulation over northeastern Asia led to the development of the NCCV activity.
文摘[Objective] The aim was to study the prediction of summer rainstorm induced by southwest vortex.[Method] Based on 2.5°×2.5° re-analysis data in four time points a day from June to August during 1971-2008 at 700 hPa in northern hemisphere provided by NECP,rainstorm and southwest vortex from June to August in Guizhou Province were studied systematically,and the forecast data of rainstorm induced by southest vortex was obtained.[Result] Southwest vortex was one of major systems influencing rainstorm in flood season(from June to August),especially in June and July;the occurrence of this kind of rainstorm was closely related to the moving path of southwest vortex,activity of cold air,environmental flow field at 500 hPa,shear line at 850 hPa,southwest jet,position of subtropical high ridge,water vapour conditions,vorticity field,etc.On the basis of factual data,objective forecast system was established and verified by means of similar method and physical diagnosis.The results showed that it was rational to choose upper trough,southwest vortex,conditions of vertical movement,southwest jet,water vapour conditions,etc.as forecast factors;when the center of southwest vortex was located in major key area(100°-105° E,25°-35° N),and secondary key area(105°-108° E,25°-35° N),regional rainstorm occurred most easily,especially in major key area with high frequency of rainstorm.[Conclusion] The study could provide references for the improvement of prediction level of rainstorm induced by southwest vortex,disaster prevention and reduction.