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A Simulation Study of a heavy rainfall Process over the Yangtze River Valley Using the Two-Way Nesting Approach

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Advances in Atmospheric Sciences 2012年第4期29卷 731-743页

作者：王树舟于恩涛王会军 Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences Climate Change Research Center Chinese Academy of Sciences

In this study, the major features of a heavy rainfall event in the Yangtze River region on 3-7 June 2011 and its event-related large-scale circulation and predictability were studied. Both observational analysis and model simulation were used, the latter being based on the Weather Research and Forecasting （WRF） model forced by NCEP Global Forecast System （GFS） datasets. It was found that, during 3-5 June, the western Pacific subtropical high apparently extended to the west and was much stronger, and the Indian summer monsoon trough was slightly weaker than in normal years. The east-west oriented shear line over the middle and lower reaches of the Yangtze River was favorable for the transportation and convergence of water vapor, and the precipitation band was located slightly to the south of the shear line. During 6-7 June, the western Pacific subtropical high retreated eastward, while the trough over the Okhotsk Sea deepened. The low vortex in Northeast China intensified, bringing much more cold air to the middle and lower reaches of the Yangtze River, and the shear line over this area moved slightly southward. The convection band moved southward and became weaker, so the rainfall during 6-7 June weakened and was located slightly to the south of the previous precipitation band. Many of the observed features, including background circulation and the distribution and amount of precipitation, were reproduced reasonably by the WRF, suggesting a feasibility of this model for forecasting extreme weather events in the Yangtze River region.

关键词： WRF Yangtze River valley heavy rainfall shear line

CHARACTERISTICS OF GRAVITY WAVE PROPAGATION AND ENERGY CONVERSION IN A SUDDEN heavy rainfall EVENT

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Journal of Tropical Meteorology 2018年第3期24卷 369-384页

作者：赵桂香王一颉王晓丽 Shanxi Meteorological Observatory Taiyuan030006China

In this paper, a sudden heavy rainfall event is analyzed, which occurred over the Yellow River midstream during 5-6 August 2014. We used observational, NCEP/NCAR reanalysis, high-resolution satellite, and numerical simulation data. The main results are as follows. Under an unfavorable environmental circulation, inadequate water vapor and unfavorable dynamic conditions but sufficient energy, a local sudden heavy rainfall was caused by the release of strong unstable energy that was triggered by cold air transport into middle and lower layers and the propagation of gravity waves. The distributions of rain area, rain clusters, and 10-minute rainfall showed typical mesoscale and microscale fluctuation characteristics. In the mesoscale rain area or upstream, there was a quasi-stationary wave of mesoscale gravity waves with their propagation downstream. In the course of propagation from southwest to northeast,the wavelength became longer and the amplitude attenuated. In the various phases of gravity wave development, there were evident differences in the direction of the wave front. Wave energy was mainly in the lower layers. Unstable vertical wind shear at heights of 1-6 km provided fluctuation energy for the gravity waves. The mechanisms of heavy rainfall formation were different at Linyou and Hancheng stations. Diabatic heating was the main source of disturbed effective potential energy at Linyou. The explosive short-period strong precipitation was caused by the release of strong effective potential energy triggered by the gravity waves, and its development and propagation after that energy maximized. In contrast, the latent heat release of upstream precipitation was the main source of disturbed effective potential energy at Hancheng. This formed a positive feedback mechanism that produced continuous precipitation. In the studied event, the development of westerly belt systems had disturbed the wind field. The contribution of kinetic energy generated by this disturbance could not be ignored. The Froude number, mounta

关键词： heavy rainfall gravity wave energy conversion terrain fluctuation

Synoptic Characteristics of heavy rainfall Events in Pre-monsoon Season in South China

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Advances in Atmospheric Sciences 2010年第2期27卷 315-327页

作者：吴丽姬黄荣辉贺海晏邵亚平温之平 Center for Monsoon and Environment Research/Department of Atmospheric Sciences Sun Yat-sen University Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Institute for Geophysics and Meteorology University of Cologne

Persistent heavy rainfall events in South China can be divided into pre-and post-monsoon-onset events according to the onset of the South China Sea Summer Monsoon. In this study, daily rainfall data from 174 stations in South China and daily NCEP/NCAR reanalysis data are used to investigate pre-monsoon-onset events. The synoptic characteristics of pre-monsoon-onset heavy rainfall events are examined in detail. It is found that 21 heavy rainfall cases happened in the pre-monsoon period between 1961 and 2005. Among them, more than 60% of the events happened under a saddle pattern circulation. Using a case study, the role of the saddle field is investigated and slantwise vorticity development （SVD） theory is applied to diagnose the mechanisms for heavy rainfall development. It is found that a low-level saddle field and low-level jets result in the accumulation of warm moist air in the lower troposphere over South China and provide the necessary unstable conditions for heavy rainfall development. The existence of a saddle field plays an important role in maintaining these unstable conditions. The slantwise movement of the isentropic surface over South China can increase local vorticity and lead to strong vertical motion, which then triggers heavy rainfall.

关键词： heavy rainfall South China pre-monsoon moist potential vorticity

Two Types of Diurnal Variations in heavy rainfall during July over Korea

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Advances in Atmospheric Sciences 2021年第12期38卷 2201-2211页

作者： Chang-Kyun PARK Minhee CHANG Chang-Hoi HO Kyung-Ja HA Jinwon KIM Byung-Ju SOHN School of Earth and Environmental Sciences Seoul National UniversitySeoul 08826Korea School of Earth and Environmental Systems Pusan National UniversityBusan 46241Korea Center for Climate Physics Institute for Basic ScienceBusan 46241Korea National Institute of Meteorological Sciences Korean Meteorological AdministrationJeju 63568Korea

This study examined the characteristics of the diurnal variations of heavy rainfall(≥110 mm in 12 hours)in Korea and the related atmospheric circulation for July from 1980−2020.During the analysis period,two dominant pattens of diurnal variation of the heavy rainfall emerged:all-day heavy rainfall(AD)and morning only heavy rainfall(MO)types.For the AD-type,the heavy rainfall is caused by abundant moisture content in conjunction with active convection in the morning(0000−1200,LST;LST=UTC+9)and the afternoon hours(1200−2400 LST).These systems are related to the enhanced moisture inflow and upward motion induced by the strengthening of the western North Pacific subtropical high and upper-tropospheric jet.For the MO-type,heavy rainfall occurs mostly in the morning hours;the associated atmospheric patterns are similar to the climatology.We find that the atmospheric pattern related to severe heavy rainfalls in 2020 corresponds to a typical AD-type and resembles the 1991 heavy-rainfall system in its overall synoptic/mesoscale circulations.The present results imply that extremely heavy rainfall episodes in Korea during the 2020 summer may occur again in the future associated with the recurring atmospheric phenomenon related to the heavy rainfall.

关键词： heavy rainfall diurnal cycle of rainfall 2020 summer summer rainy season Korea

A Study of heavy rainfall of 8-10 June, 1991 over Maharashtra, India

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Advances in Atmospheric Sciences 1994年第3期11卷 353-366页

作者： A.K.Kulkarni, B.N.Mandal and R.B.Sangam(Indian institute of Tropical Meteorology, Pune-411008, Indian Institute of Tropical Meteorology Pune India

A low pressure system from the southwest Bay of Bengal between 8-10 June, 1991 brought heavy and continuous rainfall over different parts of Maharashtra. This 3-day heavy rainspell over Maharashtra has been analysed toassess its magnitudes of point as well as areal rainfall. The analysis showed that there were 74 stations which received3-day total rainfall during 8-10 June exceeding their respective normal June rainfall. The areal raindepths obtainedfrom the rainstorm of June, 1991 have been compared with similar data of past severe rainstorms of the region whichshowed that June, 1991 rainstorm yielded higher magnitudes of raindepths upto certain size of areas. A relationshiphas also been developed between point to areal rainfall of this rainstorm for 1-3 day durations for obtaining arealraindepths.

关键词： heavy rainfall Raindepth Point rainfall Areal rainfall

SIMULATION OF BOUNDARY LAYER EFFECTS ON A heavy rainfall EVENT CAUSED BY A MESOSCALE CONVECTIVE SYSTEM OVER THE YELLOW RIVER MIDSTREAM AREA

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Journal of Tropical Meteorology 2020年第1期26卷 111-124页

作者：赵桂香王一颉王晓丽 Shanxi Meteorological Observatory Taiyuan 030006 China

A heavy rainfall event caused by a mesoscale convective system(MCS),which occurred over the Yellow River midstream area during 7-9 July 2016,was analyzed using observational,high-resolution satellite,NCEP/NCAR reanalysis,and numerical simulation data.This heavy rainfall event was caused by one mesoscale convective complex(MCC)and five MCSs successively.The MCC rainstorm occurred when southwesterly winds strengthened into a jet.The MCS rainstorms occurred when low-level wind fields weakened,but their easterly components in the lower and boundary layers increased continuously.Numerical analysis revealed that there were obvious differences between the MCC and MCS rainstorms,including their three-dimensional airflow structure,disturbances in wind fields and vapor distributions,and characteristics of energy conversion and propagation.Formation of the MCC was related to southerly conveyed water vapor and energy to the north,with obvious water vapor exchange between the free atmosphere and the boundary layer.Continuous regeneration and development of the MCSs mainly relied on maintenance of an upward extension of a positive water vapor disturbance.The MCC rainstorm was triggered by large range of convergent ascending motion caused by a southerly jet,and easterly disturbance within the boundary layer.While a southerly fluctuation and easterly disturbance in the boundary layer were important triggers of the MCS rainstorms.Maintenance and development of the MCC and MCSs were linked to secondary circulation,resulting from convergence of Ekman non-equilibrium flow in the boundary layer.Both intensity and motion of the convergence centers in MCC and MCS cases were different.Clearly,sub-synoptic scale systems in the middle troposphere played a leading role in determining precipitation distribution during this event.Although mesoscale systems triggered by the sub-synoptic scale system induced the heavy rainfall,small-scale disturbances within the boundary layer determined its intensity and location.

关键词： heavy rainfall MCS boundary layer disturbance Ekman adaptation energy wave packet propagation numerical simulation

Numerical Simulations of Impacts of Urbanization on heavy rainfall in Beijing Using Different Land-Use Data

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Acta meteorologica Sinica 2007年第2期21卷 245-255页

作者：江晓燕刘伟东 Institute of Urban Meteorology CMA

A summer strong convective precipitation event on 10 July 2004 over Beijing is numerically simulated in this paper, and the impact of urban heat island （UHI） on summer convective rain is investigated. The analysis reveals that a mesoscaie convective cloud cluster system leads to this heavy rainfall event, suggesting the supply of moisture by the large scale circulation before the initiation of precipitation, a generally weaker UHI of 2-3℃ existed in the urban area. Much like a sea breeze, the anomalously warm urban air created relatively low pressure, inducing the inflow of cooler rural air towards the urban center, which is favorable to the ascending motion and the formation of convective precipitation over the urban area. In addition, the numerical simulation of the strong convective precipitation event suggests that the simulated result of precipitation using the 2002 LANDSAT-7 land-use data with 30-m resolution is much better than that using the 1992-1993 USGS land-use data with 1-km resolution, whether in the magnitude of rainfall or in the location of precipitation. The simulation confirms to some extent that the UHI has a significant role in causing extreme rainfall event.

关键词： urban heat island （UHI） heavy rainfall numerical simulation land-use data

TRAJECTORY DIAGNOSIS OF AIR PARCELS IN HIGH-AND LOW-LEVEL JETS FOR A heavy rainfall CASE DURING MEIYU SEASON OF 1991

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Acta meteorologica Sinica 1993年第4期7卷 486-494页

作者：陶祖钰黄伟 National Laboratory for Rainstorm Research Chinese Academy of Meteorological Sciences Department of Geophysics Peking University

Trajectory diagnostic methods were used to analyze air parcels of high- and low-level jets during the heavy rainfall of 4-6 July 1991.It is found that air parcels above rainfall area travelled from the entrance of the high-level jet,passing through the jet center and reached the exit region.Upper tropospheric divergence over rainfall area resulted from decelerative motion of the jet flow.Warm and moist southwest flow converged and ascended ahead of the low-level jet. The decreasing of low-level pressure as a result of high-level divergence that caused the low-level jet became unexpectedly strong.

关键词： heavy rainfall trajectory jet

SIMULATION OF heavy rainfall IN THE SUMMER OF 1998 OVER CHINA WITH REGIONAL CLIMATE MODEL

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Acta meteorologica Sinica 2002年第3期16卷 348-362页

作者：刘一鸣丁一汇 National Climate Center Beijing 100081

The heavy rainfall in the summer of 1998 over China has been simulated with the NCC Regional Climate Model(RegCM_NCC).It was successful for RegCM_NCC to reproduce the location and seasonal shift of the seasonal rain belt in the summer of 1998 over China.The rainy season in the summer of 1998 over China can be divided into 7 episodes,including the pre-summer rainy season in South China.the Meiyu onset over the Yangtze-Huaihe River Basin,short appearance of North China rain season and the retreat of seasonal rain belt,the second Meiyu season over the Yangtze River Valley,the rainy period over the Yellow and Huaihe River Valley and the seasonal retreat of rain belt over North China.The shortcoming of the RegCM_NCC is over-estimation of precipitation amounts.The regions with large latent heat flux,upper soil moisture and total runoff are located in the rainy area and move with the simulated rain belt during the different episodes.On the contrary,the regions with small sensible heat flux are located in the simulated rainy area and move with the simulated rain belt during the different episodes.

关键词： heavy rainfall regional climate model Meiyu