An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall proce...An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall process, based on observed rainfall data and NCEP–NCAR reanalysis data through composite and diagnostic methods. The results showed that a Rossby waveguide within the subtropical westerly jet caused the event. The Rossby wave originated from strong cold air intrusion into the subtropical westerly jet over the eastern Mediterranean. With the enhancement and northward shift of the Middle East westerly jet, the Rossby wave propagated slowly eastward and deepened the India–Burma trough, which transported a large amount of moisture from the Bay of Bengal and South China Sea to southern China. Strong divergence in the upper troposphere, caused by the enhancement of the East Asian westerly jet, also favored the heavy rainfall process over Southeast China. In addition, the Rossby wave was associated with a negative-to-positive phase shift and enhancement of the North Atlantic Oscillation, but convergence in the eastern Mediterranean played the key role in the eastward propagation of the Rossby wave within the subtropical westerly jet.展开更多
[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteoro...[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteorological Station, the diagnostic analysis of atmospheric thermodynamics and dynamics on a rainstorm weather process in north-central Henan Province on July 19, 2010 was carried out. The characteristics of physical quantity field and the evolution of weather situation in north-central Henan Province when the rainstorm happened were studied. [Result] Western Pacific subtropical high strengthened to extend westward. The dynamic uplifting of low vortex at the middle and low layers, the strong water vapor transportation of southwest low-level jet caused the regional rainstorm weather process in north-central Henan Province. The diagnostic results of physical quantity showed that the deep, thick wet layer and the sustained water vapor convergence provided the abundant water vapor for rainstorm generation. The positive vorticity advection center developed and spread from northwest to southeast, which was favorable for the development of vertical movement. The structure maintenance of positive vorticity at the middle and low layers, negative vorticity at the middle and high levels provided the power condition for the regional rainstorm generation. The pumping effect of convergence at the middle and low layers, divergence at the high layer was favorable for the strengthening of vertical ascending motion at the low layer. The uplifting effect of dew point front at the middle and low layers triggered the release of unstable energy. The confrontation of warm and cold air was one of the important reasons for the regional rainstorm. TBB characteristic analysis showed that TBB was from -60 to -50 ℃ in north-central Henan Province in the whole strong precipitation time, and the moving speed was equivalent to that of southwest vortex. The low-value belt of TBB corresponded with the rainstorm occurrence zone in Henan, and the minimum-value center of TBB was basically consistent with the strongest center of precipitation. [Conclusion] The research provided the scientific basis for the short-term forecast of rainstorm.展开更多
By using the NCEP/GFS analysis data, CIMISS data, JMA and China’s Typhoon Networks, heavy rainstorm occurred in east of North China associated with Typhoon Damrey from August 3rd to 4th, 2012 was analyzed. Results sh...By using the NCEP/GFS analysis data, CIMISS data, JMA and China’s Typhoon Networks, heavy rainstorm occurred in east of North China associated with Typhoon Damrey from August 3rd to 4th, 2012 was analyzed. Results show during Damrey was going nearby Tianjin City and Hebei province of China, heavy rainstorm was observed in the cities of Qinhuangdao and Tangshan. The southerly jet stream from the southern side of the subtropical high and the periphery of Typhoon Saola is the conveyor belt for water vapor and energy, which enables Damrey to maintain for a long time and provide water vapor and heat conditions for rainfall in east of North China. The structure of Damrey caused a strong updraft in east of North China with a K-index greater than 35°C, which provided a favorable condition for the heavy rainstorm. The typhoon rainstorms in North China are the result of the interaction of the westerly, subtropical and tropical systems. In this heavy rain period, there was an obvious interaction between subtropical and tropical systems. This study has investigated the interaction between the northwestern Pacific typhoon and the North China heavy rainstorm, including the circulation characteristics of the typhoon and North China before and after the regional heavy rainstorm. Additionally, the climate background provides a reliable basis for the heavy rain forecast.展开更多
基金supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 41276002 and 41130859)the National Basic Research Program of China (Grant Nos. 2012CB955603 and 2013CB956201)+1 种基金the NSFC–Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)the Fund for Open Research Programs of the Key Laboratory of Meteorological Disaster (Nanjing University of Information Science and Technology), Ministry of Education (KLME1301)
文摘An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall process, based on observed rainfall data and NCEP–NCAR reanalysis data through composite and diagnostic methods. The results showed that a Rossby waveguide within the subtropical westerly jet caused the event. The Rossby wave originated from strong cold air intrusion into the subtropical westerly jet over the eastern Mediterranean. With the enhancement and northward shift of the Middle East westerly jet, the Rossby wave propagated slowly eastward and deepened the India–Burma trough, which transported a large amount of moisture from the Bay of Bengal and South China Sea to southern China. Strong divergence in the upper troposphere, caused by the enhancement of the East Asian westerly jet, also favored the heavy rainfall process over Southeast China. In addition, the Rossby wave was associated with a negative-to-positive phase shift and enhancement of the North Atlantic Oscillation, but convergence in the eastern Mediterranean played the key role in the eastward propagation of the Rossby wave within the subtropical westerly jet.
文摘[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteorological Station, the diagnostic analysis of atmospheric thermodynamics and dynamics on a rainstorm weather process in north-central Henan Province on July 19, 2010 was carried out. The characteristics of physical quantity field and the evolution of weather situation in north-central Henan Province when the rainstorm happened were studied. [Result] Western Pacific subtropical high strengthened to extend westward. The dynamic uplifting of low vortex at the middle and low layers, the strong water vapor transportation of southwest low-level jet caused the regional rainstorm weather process in north-central Henan Province. The diagnostic results of physical quantity showed that the deep, thick wet layer and the sustained water vapor convergence provided the abundant water vapor for rainstorm generation. The positive vorticity advection center developed and spread from northwest to southeast, which was favorable for the development of vertical movement. The structure maintenance of positive vorticity at the middle and low layers, negative vorticity at the middle and high levels provided the power condition for the regional rainstorm generation. The pumping effect of convergence at the middle and low layers, divergence at the high layer was favorable for the strengthening of vertical ascending motion at the low layer. The uplifting effect of dew point front at the middle and low layers triggered the release of unstable energy. The confrontation of warm and cold air was one of the important reasons for the regional rainstorm. TBB characteristic analysis showed that TBB was from -60 to -50 ℃ in north-central Henan Province in the whole strong precipitation time, and the moving speed was equivalent to that of southwest vortex. The low-value belt of TBB corresponded with the rainstorm occurrence zone in Henan, and the minimum-value center of TBB was basically consistent with the strongest center of precipitation. [Conclusion] The research provided the scientific basis for the short-term forecast of rainstorm.
文摘By using the NCEP/GFS analysis data, CIMISS data, JMA and China’s Typhoon Networks, heavy rainstorm occurred in east of North China associated with Typhoon Damrey from August 3rd to 4th, 2012 was analyzed. Results show during Damrey was going nearby Tianjin City and Hebei province of China, heavy rainstorm was observed in the cities of Qinhuangdao and Tangshan. The southerly jet stream from the southern side of the subtropical high and the periphery of Typhoon Saola is the conveyor belt for water vapor and energy, which enables Damrey to maintain for a long time and provide water vapor and heat conditions for rainfall in east of North China. The structure of Damrey caused a strong updraft in east of North China with a K-index greater than 35°C, which provided a favorable condition for the heavy rainstorm. The typhoon rainstorms in North China are the result of the interaction of the westerly, subtropical and tropical systems. In this heavy rain period, there was an obvious interaction between subtropical and tropical systems. This study has investigated the interaction between the northwestern Pacific typhoon and the North China heavy rainstorm, including the circulation characteristics of the typhoon and North China before and after the regional heavy rainstorm. Additionally, the climate background provides a reliable basis for the heavy rain forecast.
