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Advances in Atmospheric Sciences 2007年第3期24卷 485-502页

作者：董海萍赵思雄曾庆存 Institute of Atmospheric Physics Chinese Academy of Sciences

Analysis of a heavy rainfall in a lower latitude plateau and characteristics of water vapor transportation have been conducted by using conventional data and denser surface data. The results show：（1） the heavy rainfall was caused by a series of mesoscale systems under favorable large-scale conditions when the warm moister air and cold air interacted with each other. At the same time, the coupling between the upper- and lower-level jets was revealed. It is also found that there exists some different characteristics among the main influencing systems of heavy rainfalls in Yunnan, such as the Indian-Myanmar trough and the path of the cold air, compared with those in East and South China. （2） The interaction between mesoscale convergence lines near the ground may be a possible triggering mechanism for the occurrence of mesoscale systems, and the dynamical and thermal dynamical structure of the mesoscale systems was very obvious. The convergence lines may relate closely to the terrain of Yunnan, China. （3） The computation of the water vapor budget reveals that the primary source of water vapor supply for heavy rainfall was in the Bay of Bengal. In this case, the water vapor could be transported into Yunnan even though the amount of water vapor was less than that in the lower troposphere in East and South China. In addition, the analysis for three-dimensional air parcel trajectories better revealed and described the source location and the transportation of water vapor to Yunnan.

关键词： heavy rainfall mesoscale systems moisture budget Yunnan-Guizhou Plateau

Loess erosion change modeling during heavy rainfall

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International Journal of Sediment Research 2023年第1期38卷 24-32页

作者： Hongwu Zhang Guangquan Liu Chensu Zhao Luohao Zhang Qiang Zhang Heng Fu Shuai Cao Department of Hydraulic Engineering Tsinghua University State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research School of Civil and Environment Engineering University of Science and Technology Beijing Ordos Municipal Water Resources Bureau Ordos Municipal Water Conservancy Development Center

A typical gully sub-basin with a complex geomorphological form is used to do a model test of gravity erosion of loess by considering the sequence of slopes in a prototype gully creating a sequence of underlying surface forms in the upper reaches. The results show that the runoff from heavy rainfall is the main external force for the erosion of loess, and also is an important influencing factor to stimulate and intensify the development of gravity erosion. The soil structure and the height of the critical surface have a direct impact on the possibility of gravity erosion. Spatially, the upper section of the drainage channel mainly experiences undercutting and headcut erosion, the middle section mainly experiences lateral erosion and gravity erosion, and the lower section alternately experiences sedimentation or alluvial erosion. rainfall splash erosion produces a large amount of sand to yield high concentration mud flows in the middle and lower sections of the channel. Because of the mud flows the flood flow is obviously larger than the runoff volume formed by rainfall in a small watershed. The flood formed by high-intensity rainfall brings a large amount of sediment into the downstream rivers along the channel, indicating that under the condition that high-intensity rainfall on the Loess Plateau, lots sediment will enter the Yellow River, and the erosion deformation occurs on all slopes. Further the steep slope drainage flow causes undercutting and lateral erosion, and the soil body moves down along the slope under the action of gravity. The gully in the middle section still experience sediment washing in both depth and width,and the downstream gully continues to experiences sedimentation due to the reduction of the gradient,reflecting the adaptive adjustment of water flow and the boundary. Headcut erosion occurred on almost all slopes during different periods of rainfall, while gravity erosion mostly occurred on steep slope sections during periods of high-intensity

关键词： Gravity erosion Slope erosion Erosion modeling heavy rainfall

On the Diurnal Cycle of heavy rainfall over the Sichuan Basin during 10–18 August 2020

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Advances in Atmospheric Sciences 2021年第12期38卷 2183-2200页

作者： Rudi XIA Yali LUO Da-Lin ZHANG Mingxin LI Xinghua BAO Jisong SUN State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Department of Atmospheric and Oceanic Science University of MarylandCollege ParkCollege ParkMaryland 20742USA

A sustained heavy rainfall event occurred over the Sichuan basin in southwest China during 10–18 August 2020,showing pronounced diurnal rainfall variations with nighttime peak and afternoon minimum values,except on the first *** show that the westward extension of the anomalously strong western Pacific subtropical high was conducive to the maintenance of a southerly low-level jet(LLJ)in and to the southeast of the basin,which favored continuous water vapor transport and abnormally high precipitable water in the *** diurnal cycle of rainfall over the basin was closely related to the periodic oscillation of the LLJ in both wind speed and direction that was caused by the combination of inertial oscillation and terrain thermal *** nocturnally enhanced rainfall was produced by moist convection mostly initiated during the evening hours over the southwest part of the basin where high convective available potential energy with moister near-surface moist air was *** convective initiation took place as cold air from either previous precipitating clouds from the western Sichuan Plateau or a larger-scale northerly flow met a warm and humid current from the *** was the slantwise lifting of the warm,moist airflow above the cold air,often facilitated by southwest vortices and quasi-geostrophic ascent,that released the convective instability and produced heavy rainfall.

关键词： diurnal cycle heavy rainfall low-level jet inertial oscillation terrain Sichuan basin

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

Effect of Length Scale Tuning of Background Error in WRF-3DVAR System on Assimilation of High-Resolution Surface Data for heavy rainfall Simulation

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Advances in Atmospheric Sciences 2012年第6期29卷 1142-1158页

作者： Ji-Hyun HA Dong-Kyou LEE Atmospheric Sciences Program School of Earth and Environmental SciencesSeoul National UniversitySeoul 151-747Korea

We investigated the impact of tuning the length scale of the background error covariance in the Weather Research and Forecasting （WRF） three-dimensional variational assimilation （3DVAR） system. In particular, we studied the effect of this parameter on the assimilation of high-resolution surface data for heavy rainfall forecasts associated with mesoscale convective systems over the Korean Peninsula. In the assimilation of high-resolution surface data, the National Meteorological Center method tended to exaggerate the length scale that determined the shape and extent to which observed information spreads out. In this study, we used the difference between observation and background data to tune the length scale in the assimilation of high-resolution surface data. The resulting assimilation clearly showed that the analysis with the tuned length scale was able to reproduce the small-scale features of the ideal field effectively. We also investigated the effect of a double-iteration method with two different length scales, representing large and small-length scales in the WRF-3DVAR. This method reflected the large and small-scale features of observed information in the model fields. The quantitative accuracy of the precipitation forecast using this double iteration with two different length scales for heavy rainfall was high; results were in good agreement with observations in terms of the maximum rainfall amount and equitable threat scores. The improved forecast in the experiment resulted from the development of well-identified mesoscale convective systems by intensified low-level winds and their consequent convergence near the rainfall area.

关键词： WRF 3DVAR tuning surface data heavy rainfall

A Synoptic Overview and Moisture Tra jectory Analysis of the“7.21” heavy rainfall Event in Beijing

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Journal of Meteorological Research 2016年第1期30卷 103-116页

作者：李林涛 Albertus J.Dolman Earth and Climate Cluster Faculty of Earth and Life SciencesVU University Amsterdam

The heavy rainfall in Beijing on 21 July 2012 was a high impact event. First, a synoptic overview of this event is presented based on the ECMWF reanalysis and forecast data, together with observations of hourly precipitation. It is found that an east to northeastward moving ＂low-level northwest vortex＂ caused this event. The vortex was formed under favorable circulation patterns and intensified by low-level dry intrusions. The source regions of the large volume of moisture necessary to sustain the intense rainfall are diagnosed by back-trajectory analysis. Approximately 77% of the moisture was transported from the Bay of Bengal （BOB）. The transport processes, including vertical profiles, mean humidity variations, and relative importance of the rain-paths, are further quantified by the back-trajectory analysis and cluster analysis. The results highlight the importance of the southwestern path in transporting moisture to northern China, which accounts for 88.4% of the moisture from the BoB, and 68% of the total of the ＂7.21＂ heavy rainfall event.

关键词： heavy rainfall moisture source trajectory analysis synoptic analysis low-level vortex

Application of the moist vorticity vector in the analysis of a heavy rainfall event in North China

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Progress in Natural Science:Materials International 2007年第12期17卷 1457-1465页

作者： Zhao Yu1,2,3, Wang Jianguo4 and Xue Deqiang2(1. Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2. Shandong Provincial Meteorological Observatory, Jinan 250031, China 3. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 4. Shandong Provincial Meteorological Bureau, Jinan 250031, China) Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Shandong Provincial Meteorological Observatory Jinan 250031 China Graduate University of Chinese Academy of Sciences Beijing 100039 China Shandong Provincial Meteorological Bureau Jinan 250031 China

The moist vorticity vector (MVV), defined as (ζa×▽qv)/ρ introduced by Gao et al. is used to study a heavy rainfall event in North China. The MVV has zonal, meridional and vertical components in a three-dimensional framework. Analysis of domain-mean and mass-integrated quantities shows that the variation of the vertical component of the MVV closely follows the variation of the cloud hydrometeors, with a linear correlation coefficient of 0.95, indicating that the vertical component of the MVV is strongly associated with midlatitude convection. Further analysis shows that the vertical component of the MVV reflects the interaction between the horizontal vorticity and the horizontal specific humidity gradient, which can associate dynamic and thermodynamic processes with cloud microphysical processes. Thus, this study can help to understand how the interaction between circulations and clouds aids the development of convection, and the MVV can be used to trace the development and evolution of heavy rainfall.

关键词： moist vorticity vector heavy rainfall modeling study.

Comparison of heavy rainfall Events Originated from Different Directions of Beijing City

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Journal of Meteorological Research 2020年第6期34卷 1299-1308页

作者： Weihua YUAN Xuelin HU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 University of Chinese Academy of Sciences Beijing 100049

Strong rainfall events originated from the northeast(NE)and southwest(SW)directions of the plain area of Beijing City(BJP)over 8 recent warm seasons(May–September of 2009–2016)were analyzed by using hourly merged rainfall,satellite brightness temperature,and the fifth-generation ECMWF reanalysis(ERA5)*** heavy regional rainfall events(RREs)with different origins present quite different features in both the precipitation itself and its corresponding *** heavy RREs originated from the SW occur more frequently in the flood season of North China(July and August),and the peak time of rainfall occurrences is in the early *** are linked with stronger large-scale circulation forcing,compared with the NE-originated ***,the ratio of heavy rainfall to the total rainfall in SW-originated events,the mean spatial coverage of rainfall,and associated convective index,are also larger,for the SW *** heavy RREs from the NE occur more frequently in June and July(before the traditional flood season),with a more apparent afternoon *** exhibit stronger convective features,with higher maximum convective index values,but the large-scale forcing is weaker at the hour of *** features of the RREs from different directions of Beijing City and associated precursor circulation signals help better forecast RREs over the BJP.

关键词： heavy rainfall hourly rainfall features rainfall with different origins

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： ZHAO Gui-xiang WANG Yi-jie WANG Xiao-li Shanxi Meteorological Observatory Taiyuan 030006 China

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

关键词： heavy rainfall gravity wave energy conversion terrain fluctuation

Effect of Different Microphysical Parameterizations on the Simulations of a South China heavy rainfall

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Journal of Tropical Meteorology 2023年第1期29卷 68-86页

作者：周志敏胡杨王斌尹金方郭英莲康兆萍孙玉婷 Hubei Key Laboratory for heavy Rain Monitoring and Warning Research Institute of Heavy RainChina Meteorological AdministrationWuhan 430205 China State Key Laboratory of Sever Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 China

A heavy rainfall event in south China was simulated by the Weather Research and Forecasting(WRF) model with three microphysics schemes, including the Morrison scheme, Thompson scheme, and Milbrandt and Yau scheme(MY), which aim to evaluate the capability to reproduce the precipitation and radar echo reflectivity features, and to evaluate evaluate their differences in microphysics and the associated thermodynamical and dynamical feedback. Results show that all simulations reproduce the main features crucial for rainfall formation. Compared with the observation, the MY scheme performed better than the other two schemes in terms of intensity and spatial distribution of rainfall. Due to abundant water vapor, the accretion of cloud droplets by raindrops was the dominant process in the growth of raindrops while the contribution of melting was a secondary effect. Riming processes, in which frozen hydrometeors collect cloud droplets mainly, contributed more to the growth of frozen hydrometeors than the Bergeron process. Extremely abundant snow and ice were produced in the Thompson and MY schemes respectively by a deposition process. The MY scheme has the highest condensation and evaporation, but the lowest deposition. As a result, in the MY scheme, the enhanced vertical gradient of condensation heating and evaporation cooling at low levels produces strong positive and weak negative potential vorticity in Guangdong, and may favor the formation of the enhanced rainfall center over there.

关键词： heavy rainfall microphysical parameterization hydrometeor budget diabatic heating