| Summer rains and floors are major natural disasters and extreme weather events in China regional.Rainstorm in east China regional and closely linked to the Asian monsson.This article reveals in the context of climate change interannual variability of heavy rain in east China. Asia reflects the world within the scope of a typical monsoon climate change.This article focuses on the qinghai-tibet plateau big topographic influence and the water vapor transport structure impact on China’s eastern time and space distribution of rainstorm extreme events.Analysis of spatial distribution of summer rainstorm frequency from 1961 to 2010 indicates that it decreases from the southeast to the northwest at the east edge of the large-scale topography associated with the plateaus.Regional monsoon region often happen in China, a wide range of extreme storm events, but the cause of this unusual rainstorm event and its change law exists many uncertain factors.Under the background of global climate change rate and the change of summer precipitation in the east of China annual rainstorm extreme events frequency variation in spatial distribution in China "three steps" terrain significant regional differences. It is shown that moist characteristics of summer precipitation and extreme rainstorms during the monsoon season in East China, including moisture transport pathways, moist flow pattern, and spatial structure of the merging area of moist flows, differs significantly.Spatial distribution of rainstorms with daily rainfall greater than 50 mm is characterized by the “high in the southeast and low in the northwest” pattern, similar to the staircase distribution of the topography.The merging area for moist flow associated with rainstorms in high frequency region is located slightly to the south of the monsoonal precipitation or non-rainstorm precipitation, with significantly strong moisture convergence. It is shown that column-integrated moist transport vortex and structure of moist flux convergence has significant impact on the north-south oscillation of frequent rainstorm areas in East China, which is synchronization with the maximum vorticity of moisture transport and the minimum of convergence in the decadal time scale. Synthesis of moisture transport pathways and related circulation impact leads to a conceptual model of moisture flow associated with rainstorms.Asian summer monsoon(including both East Asian monsoon and South Asian monsoon) is the largest and most pronounced circulation system in the world, its change could controlled by mechanical and thermal forcing of the TP, because as a vast elevated landmass, the Tibetan Plateau forms a huge heat source protruding into the free atmosphere.A conceptual model to reveal the typical pattern of water vapor transport associated with the extreme heavy rainfall in North China during the summer has been proposed in this paper. The conceptual model depicts the interaction between the westerlies and water vapor transport along the north edge of the Tibetan Plateau(TP) as well as the southwesterly bypassing flow along the east edge of the TP. The westerly jets in the south and north of the TP and the bypassing flow along the south and north edges of the TP have major contributions to the water vapor and vorticity transport accounting for the heavy rainfall. During East Asian Mei-Yu season, the low trough over Baikal collocate with the cyclonic flow of water vapor transport separated from north edge of the TP, the northward water vapor transport(monsoon water vapor transport) ahead of the trough in the east of the TP is also one of the important water vapor sources for heavy rainfall in North China.The water vapor transport model clearly shows there are three water vapor transport channels. Two of them are associated with the bypassing flow along the north and east edge of the TP and the other one is related to the southerly flow in the west of the anti-cyclone over the Korean Peninsula. These three water vapor transport channels merge in the middle and lower reaches of the Yellow River(North China and Northeast China area).The two “belt” areas with strong correlation both merge with those three water vapor transport synchronously in the middle and lower reaches of the Yellow River.According to the analysis of correlation patterns of the stream function of water vapor flux, it can be found that the heavy rainfall regions in the northern China,especially in North China, are beneath the convergence zone of the Mongolian Plateau cyclonic circulation, the anti-cyclonic circulation over the Korean Peninsula and multiple monsoon circulations(entrance). The results from this study suggest that orographic bypassing mechanisms account for the heavy rainfall in North Chinaare beneficial to the transport of the middle-lower latitude eddy energy and water vapor to the middle and lower reaches of the Yellow River.This article also aimed at the middle and lower reaches of the Yangtze river on July 11, 2000-13, torrential rain process.Through the potential- stream function dynamic analytic upstream of the qinghai-tibet plateau characteristics of water vapor transportation power systems "strong signal", reveals a wide range of thunderstorms and heavy rain in Yangtze river basin upstream occurrence, development process of the qinghai-tibet plateau potential-stream function field power system three-dimensional structure characteristics of "strong signal".Potential- stream function field derived from the eastern qinghai-tibet plateau vortex structure and ascending motion area significantly shift process is also the Yangtze river basin upstream "strong signal" one heavy rain process.In this paper, through 3 d structure analysis related to the potential- stream function field can describe the early stage of the heavy rain process in the middle and lower reaches of the Yangtze river water vapor transportation power systems(flux, vorticity, divergence) effect mechanism,In this paper show that the three-dimensional structure related to the potential- stream function field track analysis method,can be more clear early heavy rain process in the middle and lower reaches of the Yangtze river water vapor transportation power systems to the east of the qinghai-tibet plateau affect physical picture. |
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