Monitoring Of Extreme Precipitation Events In Eastern China And Analysis Of Low Frequency Characteristics

Using the daily precipitation grid data in China from 1979 to 2015,and comprehensively considering the objective method of precipitation time-influenced area-intensity,it can automatically identify regional extreme precipitation events in eastern China,and determine the frequency,duration,affected area,and relative strength,compared with the current monitoring results of the National Climate Center.Using the European Center's reanalysis data,through the methods of ensemble empirical mode decomposition,water vapor budget diagnosis,synthetic analysis,etc.the main physical processes affecting the occurrence of Short Regional Extreme Precipitation and Persistent Regional Extreme Precipitation events and their key low-frequency scale evolution characteristics are studied.Discuss the evolution and modulation of key scale tropospheric high,middle and low tropospheric system configuration.The main conclusions obtained are as follows:(1)Comprehensive consideration of regional-precipitation time-area-intensity(Regionoal-Time-Square-Intensity,RTSI)method is similar to the statistical and climatic characteristics of extreme precipitation events identified by the National Climate Center's operational monitoring method.The RTSI method can objectively recognize the extremely precipitation event with a small scale,slower movement,such as the extreme precipitation event of the persistent extraction event in South China and the Yangtze River Basin and the daily precipitation less than 50 mm.The operational method can identify extreme precipitation events that occur quickly in North China.(2)Diagnosis of extreme precipitation in the area,during the occurrence period,its precipitation intensity is mainly influenced by the radiopathic level of regional atmosphere,which is caused by the north and south to abnormal water vapor spoke,where the south side is the main water vapor input boundary.In the early stage of SREP,the atmosphere water vapor was abnormal,and the net inflow of water vapor with the south side of the region was related to net inflows in the north side.In the early stage of Prep,the north and south borders of the region had an unusual water vapor.The spatial distribution shows that,with the atmospheric column water vapor and moisture level convergence effects triggered and sustained extreme precipitation.(3)Scale analysis of the main physical process,found that SREP is mainly affected by the weather scale and 10-30 d of Quasi-biweekly Oscillation.At the weather scale,water vapor mainly comes from the Northwest Pacific.The water vapor in the 10-30 d scale region is obvious from the Indian Ocean.PREP is more affected by QBWO and 30-90 d of Madden-Julian Oscillation scale,the overlapping of two-scale water vapor-irradiated has formed a sustained strong precipitation.The QBWO water vapor mainly comes from the Northwest Pacific,and MJO water vapor is from the Northwest Pacific and Indian Ocean.(4)The water vapor budget of the entire atmospheric column is related to the synergistic effects of the stable high pressure in the upper troposphere,the lower cyclone and the different configurations of the Pacific anticyclone system.Before and after the SREP,the low-rise weather scale wind field quickly turned into cyclone,and the day and 10-30 d scales were combined,and the strong water vapor is strong,and the high-altitude high pressure is weak.There is a good correspondence between the middle layers of the flow layer,and the hypothetical position temperature high value region,which can be used as an indicator triggering of the precipitation,and may be affected by the mid-high latitude.The low-level system affecting the PREP is 10-30 d components of the Northwest Pacific Anti-cyclone with Southwest Moving.The cyclone of the MJO scale in the middle of the Yangtze River and the gas transfer of the northwest Pacific,strengthened the moisture of water.High-level high-voltage high pressure existence of 10-30 d component.There is a certain relationship between the stable maintenance and persistence of the position temperature high value center.