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Convective Asymmetries Associated with Tropical Cyclone landfall: β-Plane Simulations

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Advances in Atmospheric Sciences 2010年第4期27卷 795-806页

作者：黄伟梁旭东 Shanghai Typhoon Institute China Meteorological Administration

The physical processes associated with changes in the convective structure of an idealized tropical cyclone （TC） during landfall on a beta-plane were studied using the fifth-generation Pennsylvania State University- National Center for Atmospheric Research Mesoscale Model, version 3 （MM5）. The simulation results suggested that the suppression of moisture supply and increased friction acted to enhance the convection from the left and front quadrants of the TC to the front and right of the TC during different periods of landfall. When surface moisture flux was turned off, convection in other parts of the quadrant was clearly suppressed and the total rainfall was reduced. When surface friction was increased, precipitation showed a marked increase after the TC made landfall. Wetter air at low and intermediate levels, and drier air at high levels around the onshore side of the coastline led to a high value of convective available potential energy （CAPE）. Consequently, convection was enhanced immediately downstream of this area when the surface moisture flux was cut off. When surface friction was increased, the physical process was similar prior to landfall. After landfall, increased convergence at the onshore side of the land resulted in enhanced convection in front of the TC. Consistent with previous findings, our results suggest that during landfall the TC structure changes from one of thermodynamic symmetry to asymmetry due to differential moisture flux between the land and sea surface. The asymmetry of the thermodynamic structure, which can be explained by the distribution of CAPE, causes an asymmetric rainfall structure.

关键词： tropical cyclone landfall convective asymmetry

A Diagnostic Study of the Asymmetric Distribution of Rainfall during the landfall of Typhoon Haitang(2005)

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Advances in Atmospheric Sciences 2015年第10期32卷 1419-1430页

作者： YUE Caijun GAO Shouting LIU Lu LI Xiaofan Shanghai Typhoon Institute China Meteorological Administration Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Earth Sciences Zhejiang University

The precipitation during landfall of typhoon Haitang （2005） showed asymmetric structures （left side/right side of the track）. Analysis of Weather Research and Forecasting model simulation data showed that rainfall on the right side was more than 15 times stronger than on the left side. The causes were analyzed by focusing on comparing the water vapor flux, stability and upward motion between the two sides. The major results were as follows：（1） Relative humidity on both sides was over 80%, whereas the convergence of water vapor flux in the lower troposphere was about 10 times larger on the right side than on the left side. （2） Both sides featured conditional symmetric instability [MPV （moist potential vorticity）〈0], but the right side was more unstable than the left side. （3） Strong （weak） upward motion occurred throughout the troposphere on the right （left） side. The Q vector diagnosis suggested that large-scale and mesoscale forcing accounted for the difference in vertical velocity. Orographic lift and surface friction forced the development of the asymmetric precipitation pattern. On the right side, strong upward motion from the forcing of different scale weather systems and topography caused a substantial release of unstable energy and the transportation of water vapor from the lower to the upper troposphere, which produced torrential rainfall. However, the above conditions on the left side were all much weaker, which led to weaker rainfall. This may have been the cause of the asymmetric distribution of rainfall during the landfall of typhoon Haitang.

关键词： landfall typhoon rainfall asymmetric distribution water vapor atmospheric stability vertical motion

Impacts of Soil Moisture on the Numerical Simulation of a Post-landfall Storm

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Journal of Meteorological Research 2019年第2期33卷 206-218页

作者： Feimin ZHANG Zhaoxia PU Chenghai WANG College of Atmospheric Sciences Lanzhou University Department of Atmospheric Sciences University of Utah

Surface heat and moisture fluxes are important to the evolution of a tropical storm after its landfall. Soil moisture is one of the essential components that influence surface heating and moisture fluxes. In this study, the impact of soil moisture on a pre-landfall numerical simulation of Tropical Storm Bill(2015), which had a much longer lifespan over land, is investigated by using the research version of the NCEP Hurricane Weather Research and Forecasting(HWRF) model. It is found that increased soil moisture with SLAB scheme before storm's landfall tends to produce a weaker storm after landfall and has negative impacts on storm track simulation. Further diagnoses with different land surface schemes and sensitivity experiments indicate that the increase in soil moisture inside the storm corresponds to a strengthened vertical mixing within the storm boundary layer, which is conducive to the decay of storm and has negative impacts on storm evolution. In addition, surface diabatic heating effects over the storm environment are also found to be an important positive contribution to the storm evolution over land, but their impacts are not so substantial as boundary layer vertical mixing inside the storm. The overall results highlight the importance and uncertainty of soil moisture in numerical model simulations of landfalling hurricanes and their further evolution over land.

关键词： soil moisture tropical storm tropical cyclone landfall la nd surface numerical simulation

Lightning Activity and Precipitation Characteristics of Typhoon Molave(2009) Around Its landfall

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Acta meteorologica Sinica 2013年第5期27卷 742-757页

作者：张文娟张义军周秀骥 State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences University of Chinese Academy of Sciences

Cloud-to-ground （CG） lightning data,storm intensity and track data,and the data from a Doppler radar and the Tropical Rainfall Measuring Mission （TRMM） satellite,are used to analyze the temporal and spatial characteristics of lightning activity in Typhoon Molave （0906） during different periods of its landfall （pre-landfall,landfall,and post-landfall）.Parameters retrieved from the radar and the satellite are used to compare precipitation structures of the inner and outer rainbands of the typhoon,and to investigate possible causes of the different lightning *** results indicate that lightning activity was stronger in the outer rainbands than in the eyewall and inner *** mainly occurred to the left （rather than ＂right＂ as in previous studies of US cases） of the moving typhoon,indicating a significant spatial *** maximum lightning frequency in the tropical cyclone （TC） eyewall region was ahead of that in the whole TC region,and the outbreaks of eyewall lightning might indicate deepening of the *** lightning in the outer rainbands is found to be associated with stronger updraft,higher concentrations of rain droplets and large ice particles at elevated mixed-phase levels,and the higher and broader convective clouds in the outer *** to the contribution of large cloud nuclei,lightning intensity in the outer rainbands has a strong positive correlation with radar *** ratio of positive CG lightning in the outer rainbands reached its maximum 1 h prior to occurrence of the maximum typhoon intensity at 2000 Beijing Time （BT） 18 July *** the pre-landfall period （0300 BT 18 July-0050 BT 19 July）,the typhoon gradually weakened,but strong lightning still *** the typhoon made landfall at 0050 BT 19 July,CG lightning density rapidly decreased,but the ratio of positive lightning ***,after the landfall of the outer rainbands at 2325 BT 18 July （approximately 1.5 h prior to the l

关键词： Molave typhoon landfall lightning precipitation structure

Cluster Analysis of Tropical Cyclones Making landfall on the Korean Peninsula

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Advances in Atmospheric Sciences 2009年第2期26卷 202-210页

作者： Ki-Seon CHOI Baek-Jo KIM Chee-Young CHOI Jae-Cheol NAM National Institute of Meteorological Research Seoul Republic of Korea Korea Meteorological Administration Seoul Republic of Korea

Cluster analysis has been performed on the tracks of 51 Tropical Cyclones （TCs） that made landfall on the Korean Peninsula （KP） for the period of 1951-2004. The classification technique of the landfalling tracks used in this study was the fuzzy clustering method （FCM） and the resultant silhouette coefficient suggested four clusters as an optimal cluster number. Most TCs of Cluster 2 and Cluster 3 （C-23） tended to pass through China's Mainland before landfall, but those of Cluster 1 and Cluster 4 （C-14） tended to mostly land after moving northward from the East China Sea （ECS） without passing over China's Mainland. The TC landfalling frequency of C-14 has begun to clearly increase since the late 1980s, particularly the maximum landfalling frequency in the early 2000s set a record for the 54-year analysis period. The ridge axis of the western North Pacific high （WNPH） of C-23 bends more equatorward than that of C-14, so that the monsoon trough of C-23 is located more equatorward than that of C-14. As a consequence, most TCs of C-23 tend to recurve inland of China, but over the ECS for C-14.

关键词： Korean Peninsula tropical cyclone landfall fuzzy cluster Arctic Oscillation Nino-3.4

A COMPOSITE STUDY OF RAINFALL ASYMMETRY OF TROPICAL CYCLONES AFTER MAKING landfall IN GUANGDONG PROVINCE

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Journal of Tropical Meteorology 2017年第4期23卷 417-425页

作者：温冠环刘春霞毕雪岩黄辉军 Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510080 China

Based on observed rainfall data, this study makes a composite analysis of rainfall asymmetry in tropical cyclones(TCs) after making landfall in Guangdong province(GD) during 1998—2015. There are 3.0 TCs per year on average making landfall in GD and west of GD(WGD) has the most landfall TCs. Most of TCs make landfall in June,July, August, and September at the intensities of TY, STS, and TS. On average, there is more rainfall in the southwest quadrant of TC in CGD(center of GD), WGD, and GD as a whole, and the maximum rainfall is located in the southwest near the TC center. The mean TC rainfall in the east of GD(EGD) leans to the eastern side of TC. The TC rainfall distributions in June, July, August, and September all lean to the southwest quadrant and the maximum rainfall is located in the southwest near the TC center. The same features are found in the mean rainfall of TD, TS, STS, TY,and STY. The maximum rainfall is mainly in the downshear of vertical wind shear. Vertical wind shear is probably the dominate factor that determines asymmetric rainfall distribution of TCs in GD. Storm motion has little connection with TC rainfall asymmetry in GD.

关键词： rainfall asymmetry tropical cyclone landfall

AN ANALYSIS OF DISTRIBUTION AND MESOSCALE STRUCTURE OF PRECIPITATION ABOUT landfall TROPICAL CYCLONE KOPPU(0915)

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Journal of Tropical Meteorology 2016年第4期22卷 445-454页

作者：安成袁金南蒙伟光张艳霞蒋德海 Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction CMA Army Troops Unit 68028

Observation from automatic weather stations, radars and TRMM satellites are employed to investigate the precipitation distribution of tropical cyclone(TC) Koppu(0915) that made landfall on Guangdong province in *** results show that the precipitation of landfall TC Koppu is featured by significant asymmetry and mesoscale structure, and occurs mainly to the left of its moving path. By examining the sea surface temperature(SST), water vapor flux, Q vector, vertical wind shear of environment etc., it is found out that the distribution of SST, water vapor convergence, low-level convective ascending and vertical wind shear facilitates the TC precipitation to take place to the left of the TC moving path. The mesoscale structure separated by Barnes band-pass filter presents that the precipitation of landfall KOPPU has some organized mesoscale spiral structures, which is around the TC center and composed of the form of belts or blocks. The heavy local rainfall of landfall TC Koppu is primarily associated with the rainfall due to mesoscale spiral structure.

关键词： precipitation characteristics diagnostic analysis landfall TC KOPPU asymmetric distribution mesoscalestructure

ANALYSIS ON THE CHARACTERISTICS OF TROPICAL CYCLONES MAKING landfall ON DIFFERENT REGIONS OF CHINESE MAINLAND

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Journal of Tropical Meteorology 2013年第3期19卷 276-283页

作者：尹宜舟朱志存叶殿秀黄强 Center for Earth System Science Tsinghua University National Climate Center China Meteorological Administer Nanjing University of Information Science & Technology Pinghu Meteorological bureau Zhejiang Province Haining Meteorological bureau Zhejiang Province

The locations(longitudes and latitudes)of the tropical cyclones(TCs)making landfall on the Chinese mainland from 1949 to 2008 are investigated in detail by using ArcGis and FORTRAN *** southeast coastline[110 to 122°E)with most landfall TCs was selected as the key region,which was divided into 12 subsections with 1°intervals of *** study period was from July to September in each *** result showed that the average sustaining time of TCs making landfall on the subsections east of 118°E is longer than those west of 118°*** landfall,the averaged TC intensity in the subsections east of118°E is stronger than that west of *** landfall,however,the difference between the west and east is not *** index of destructive potential for the period before/after landfall was defined as TDP1/*** maximum of TDP1/TDP2 occurred in the subsection of[119,120°E)/[110,111°E).The ENSO impact on the frequency and average location of landfall TC over the whole region at 110 to 122°E is not obvious,but the effect varies with specific *** is little differences of averaged TDP1 in the subsections between different phases of ENSO events,but the averaged TDP2 is larger in the warm events than that in the cold *** rainstorm days of each station caused by TCs in different subsections were counted *** results suggested that the rainstorm days of the subsections east of 118°E are much more than those west of 118°*** larger values are primarily distributed at the subsections of[119,120°E)and[110,111°E).

关键词： Chinese mainland landfall tropical cyclone characteristics analysis destructive potential rainstorm frequency

VARIATION CHARACTERISTICS OF TROPICAL CYCLONES MAKING landfall IN CHINA AT DIFFERENT INTENSITIES

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Journal of Tropical Meteorology 2011年第3期17卷 268-275页

作者：许向春于玉斌赵大军 Department of Atmospheric Science Lanzhou University Hainan Institute of Meteorological Science China Meteorological Administration Training Center Nanjing University of Information Science and Technology

According to the national standard(2006)on tropical cyclone(TC)intensity,TCs are categorized into six intensity types,namely,tropical depression(TD),tropical storm(TS),severe tropical storm(STS), typhoon(TY),severe typhoon(STY),and super severe typhoon(SSTY).Fifty-eight years(1949–2006)of the datasets from the Yearbook of Typhoons and Yearbook of Tropical Cyclones were used to study the variation characteristics of TCs making landfalls in China's Mainland,Hainan and Taiwan *** main results are as ***,interannual or interdecadal variations in the number of landfalling TCs at different intensities *** far as long-term trends are concerned,the TD and TS frequencies show a significant linearly decreasing trend while those of STY show a significant linearly increasing ***, a significant period of 6–8 years exist in the variations of annual landfalling TD,TS,and STS frequencies while quasi-16-year periods are found in the annual TY ***,TD and TS are generated mostly over the South China Sea,while TY,STY,and SSTY mostly over the waters southeast of the Bashi Channel and the ocean to the east of the ***,as far as interdecadal trends are concerned,the frequencies of landfalling TD and TS generated over the South China Sea show significant linearly decreasing ***,TY and STY show significant linearly increasing trends.

关键词： statistical characteristics tropical cyclones landfall variation trends