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Can Adaptive Observations Improve tropical cyclone Intensity Forecasts?

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Advances in Atmospheric Sciences 2014年第2期31卷 252-262页

作者： QIN Xiaohao MU Mu State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences

In order to investigate whether adaptive observations can improve tropical cyclone （TC） intensity forecasts,observing system simulation experiments （OSSEs） were conducted for 20 TC cases originating in the western North Pacific during the 2010 season according to the conditional nonlinear optimal perturbation （CNOP） sensitivity,using the fifth version of the PSU/NCAR mesoscale model （MM5） and its 3DVAR assimilation system.A new intensity index was defined as the sum of the number of grid points within an allocated square centered at the corresponding forecast TC central position,that satisfy constraints associated with the Sea Level Pressure （SLP）,near-surface horizontal wind speed,and accumulated convective *** higher the index value is,the more intense the TC *** impacts of the CNOP sensitivity on the intensity forecast were then *** OSSE results showed that for 15 of the 20 cases there were improvements,with reductions of forecast errors in the range of 0.12％-8.59％,which were much less than in track *** indication,therefore,is that the CNOP sensitivity has a generally positive effect on TC intensity forecasts,but only to a certain *** conclude that factors such as the use of a coupled model,or better initialization of the TC vortex,are more important for an accurate TC intensity forecast.

关键词： adaptive observation tropical cyclone intensity forecast conditional nonlinear optimal perturbation

Topographic effects on polar low and tropical cyclone development in simple theoretical model

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Applied Mathematics and Mechanics(English Edition) 2009年第10期30卷 1271-1282页

作者：李子良傅刚郭敬天端义宏张美根 Department of Marine Meteorology Ocean University of China Shanghai Typhoon Institute State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences North China Sea Marine Forecasting Center of State Oceanic Administration National Meteorological Center China Meteorological Administration

The polar low and tropical cyclone type vortices over topography are assumed to be the axisymmetrical and thermal-wind balanced systems, which are solved as an initial value problem of a linearized vortex equation set in cylindrical coordinates. The roles of the sensible and latent heating, friction, and topography in the structure and intensification of the polar low and tropical cyclone type vortices are analyzed. The radial velocity, vertical velocity, azimuthal velocity, and the unstable growth rate including the topography effects are obtained. It is shown that the interaction between the flow and the topography plays a significant role in the structure and intensification of the polar low and tropical cyclone system. The analysis of the topography term indicates that, in the up-slope side of the mountain, the radial inflow and the vertical ascent forced by the mountain can intensify the polar low and tropical cyclone type vortex and increase the unstable growth rate. However, in the lee side of the mountain, the radial inflow and the vertical descent forced by the mountain can weaken the polar low and tropical cyclone type vortex and decrease the unstable growth rate of the polar low and tropical cyclone system. In addition, the evolutionary process and the spatial structure of the polar low observed over the Japan Sea on 19 December 2003 are investigated with the observational data to verify this theoretical result.

关键词： topography analytical solutions polar low tropical cyclone

Derivation of Parametric tropical cyclone Models for Storm Surge Modeling

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China Ocean Engineering 2010年第2期24卷 245-254页

作者：王志力陆永军耿艳芬 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Transportation College Southeast University

In this paper, the parametric tropical cyclone models for storm surge modeling are further developed. Instead of tangential wind speed via cyclostrophic balance and radial wind speed using a simple formulation of defection angle, the analyrical expressions of tangential and radial wind speed distribution are derived from the governing momentum equations based on the general symmetric pressure distribution of Holland and Fujita. The radius of the maximum wind is estimated by tropical cyclone wind structure which is characterized by the radial extent of special wind speed. The shape parameter in the pressure model is estimated by the data of several tropical cyclones that occurred in the East China Sea. Finally, the Fred cyclone （typhoon 199417） is calculated, and comparisons of the measured and calculated air pressures and wind speed are presented.

关键词： tropical cyclone parametric tropical cyclone model storm surge radius of maxirmun wind shapeparameter

A simplified index to assess the combined impact of tropical cyclone precipitation and wind on China

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Frontiers of Earth Science 2019年第4期13卷 672-681页

作者： Peiyan CHEN Hui YU Ming XU Xiaotu LEI Feng ZENG Shanghai Typhoon Institute China Meteotological AdministrationShanghai 200030China The Joint Laboratory for Typhoon Forecasting Technique Applications between Shanghai Typhoon Institute and Wenzhou Meteorological Bureau Wenzhou 325000China Key Laboratory of Numerical Modeling for tropical cyclone China Meteotological AdministrationShanghai 200030China Shanghai Meteorological Service Shanghai 200030China Wenzhou Meteorological Bureau Wenzhou 325000China

Relationships between tropical cyclone(TC)precipitation,wind,and storm damage are analyzed for China based on TCs over the period from 1984 to *** analysis shows that the maximum daily areal precipitation from stations with daily precipitation of ≥50 mm and the sum of wind gusts of ≥13.9 m/s can be used to estimate the main damage caused by TCs,and an index combining the precipitation and wind gust of a TC(IPWT)is defined to assess the severity of the combined impact of precipitation and *** correlation coefficient between IPWT and the damage index for affecting TCs is 0.80,which is higher than that for only precipitation or *** TCs with precipitation and wind affecting China are divided intofive categories,Category 0 to Category 4,based on IPWT,where higher categories refer to higher combined impacts of precipitation and *** combined impact category is closely related to damage category and it can be used to estimate the potential damage category in operational *** are 87.7%,72.9%,69.8%,and 73.4%of cases that have the same or one category difference between damage category and combined impact category for Categories 1,2,3,and 4,*** and its classification can be used to assess the severity of the TC impact and of combined precipitation and wind conveniently and accurately,and the potential damage caused by *** result will be a good supplementary data for TC intensity,precipitation,wind,and *** addition,IPWT can be used as an index to judge the reliability of damage *** analysis of the annual frequency of combined precipitation-wind impact categories reveals no significant increasing or decreasing trend in impact over China over the past 30 years.

关键词： tropical cyclone impact precipitation wind

Effects of the East Asian Summer Monsoon on tropical cyclone Genesis over the South China Sea on an Interdecadal Time Scale

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Advances in Atmospheric Sciences 2012年第2期29卷 249-262页

作者：王鑫周文李崇银王东晓 Guy Carpenter Asia-Pacific Climate Impact Centre School of Energy and EnvironmentCity University of Hong Kong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Meteorological College PLA University of Science and Technology State Key Laboratory of tropical Oceanography South China Sea Institute of OceanologyChinese Academy of Sciences

tropical cyclone （TC） genesis over the South China Sea （SCS） during 1965–2004 was analyzed. The locations of TC genesis display evident seasonal changes, with the mean position of formation situated north of 15 °N in summer （June–July–August） and south of 15 °N in autumn （September–October–November）. The TC genesis in summer underwent dramatic interdecadal variations, with more and less TC frequency during 1965–1974/1995–2004 and 1979–1993, respectively. In contrast, a significant interannual variation of TC genesis with a period of ～4 years was observed in autumn. This study investigated the relationship of SCS TC genesis to the East Asian jet stream （EAJS） and the western North Pacific subtropical high （WNPSH） on an interdecadal time scale. Analysis and comparison of the impacts of the EAJS and the WNPSH on vertical wind shear changes indicate that changes in the WNPSH and EAJS intensity rather than EAJS meridional location are responsible for changes in TC genesis on an interdecadal time scale. Corresponding to a weaker EAJS, anomalous Rossby wave energy at upper levels displays equatorward propagation at midlatitudes and poleward propagation in the subtropics. This induces anomalous convergence and divergence of wave activity fluxes in East Asia around 30 °N and the SCS, respectively. The anomalous divergence of wave activity fluxes reduces easterlies at upper levels over the SCS, which is favorable to TC genesis.

关键词： tropical cyclone subtropical jet stream South China Sea

Identifying the Spatial Structure of Black Hole and tropical cyclone Based on a Theoretical Analysis of Orthogonal Interaction

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Journal of Modern Physics 2023年第6期14卷 933-952页

作者： Weihong Qian Guangzhou Institute of tropical and Marine Meteorology CMA Guangzhou China School of Physics Peking University Beijing China

Black holes are recognized by Newton’s gravitational theory and Einstein’s general relativity, but there is still a lack of understanding the spatial structure of events, especially the nature of event horizon. In this paper, a theoretical analysis is used to compare the structures of tropical cyclone in the atmosphere and black hole in the astronomy so that five results are: 1) Both of them share the similar spatial structure, with tropical cyclone and black hole having the outflow cloud shield and the horizon sphere in the central part, respectively, while four spiral material bands exist in the rotating plane around them;2) In theoretically, the energy density formed by the orthogonal interaction of the four spiral material bands is as times as the total kinetic energy of the head-on interaction;3) This region of high energy density can lead to the conversion from mass to energy and the creation of new physical states of matter, which is a black hole event;4) The outer horizon of a black hole is the outermost interface of events, or the orthogonal interaction interface of particles;5) High-speed plasma jets extended at the poles of the black hole are directly associated with the shear stress of orthogonal interaction.

关键词： Black Hole Event Horizon tropical cyclone Spatial Structure Orthographic Interaction

CLIMATE PREDICTION EXPERIMENT FOR tropical cyclone GENESIS FREQUENCY USING THE LARGE-SCALE CIRCULATION FORECAST BY A COUPLED GLOBAL CIRCULATION MODEL

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Journal of tropical Meteorology 2014年第2期20卷 103-111页

作者：贾小龙陈丽娟罗京佳 National Climate Center Laboratory for Climate Studies China Meteorological Administration Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Climate Variation Predictability and Applicability Research Program Research Institute for Global Change Japan Agency for Marine-Earth Science and TechnologyJapan

Based on an analysis of the relationship between the tropical cyclone genesis frequency and large-scale circulation anomaly in NCEP reanalysis, large-scale atmosphere circulation information forecast by the JAMSTEC SINTEX-F coupled model is used to build a statistical model to predict the cyclogenesis frequency over the South China Sea and the western North Pacific. The SINTEX-F coupled model has relatively good prediction skill for some circulation features associated with the cyclogenesis frequency including sea level pressure, wind vertical shear, Intertropical Convergence Zone and cross-equatorial air flows. Predictors derived from these large-scale circulations have good relationships with the cyclogenesis frequency over the South China Sea and the western North Pacific. A multivariate linear regression(MLR) model is further designed using these predictors. This model shows good prediction skill with the anomaly correlation coefficient reaching, based on the cross validation, 0.71 between the observed and predicted cyclogenesis frequency. However, it also shows relatively large prediction errors in extreme tropical cyclone years(1994 and 1998, for example).

关键词： CGCM large-scale circulation tropical cyclone climate prediction

Maintenance of tropical cyclone Bill (1988) after Landfall

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Acta meteorologica Sinica 2013年第4期27卷 486-501页

作者：徐亚梅 Department of Geosciences Zhejiang University

The mechanism for the maintenance of tropical cyclone Bill （1988） after landfall is investigated through a numerical simulation. The role of the large-scale environmental flow is examined using a scale separation technique, which isolates the tropical cyclone from the environmental flow. The results show that Bill was embedded in a deep easterly-southeasterly environmental flow to the north-northeast of a large-scale depression and to the southwest of the western Pacific subtropical high. The depression had a quasi-barotropic structure in the mid-lower troposphere and propagated northwestward with a speed similar to the northwestward movement of Bill. The moisture budgets associated with both the large-scale and the tropical cyclone scale motions indicate that persistent low-level easterly-southeasterly flow transported moisture into the inner core of the tropical cyclone. The low-level circulation of the tropical cyclone transported moisture into the eyewall to support eyewall convection, providing sufficient latent heating to counteract energy loss due to surface friction and causing the storm to weaken relatively slowly after landfall. Warming and a westward extension of the upper-level easterly flow led to westward propagation of the environmental flow in the mid-lower troposphere. As a result, Bill was persistently embedded in an environment of deep easterly flow with high humidity, weak vertical wind shear, convergence in the lower troposphere, and divergence in the upper troposphere. These conditions are favorable for both significant intensification prior to landfall and maintenance of the tropical cyclone after landfall.

关键词： tropical cyclone maintenance after landfall scale separation technique moisture budgets favorable environment

Relationship between the tropical cyclone genesis over the Northwest Pacific and the sea surface temperature anomalies

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Progress in Natural Science:Materials International 2007年第10期17卷 1208-1212页

作者： Wang Jinbo, Qian Weihong and Zhang Xin(Monsoon and Environment Research Group, School of Physics, Peking University, Beijing 100871, China) Monsoon and Environment Research Group School of Physics Peking University Beijing 100871 China

Using the tropical cyclone (TC) data derived from the Joint Typhoon Warning Center (JTWC) and the sea surface temperature data derived from the Joint Environmental Data Analysis Center (JEDAC) at the Scripps Institute of Oceanography from January 1955 to December 2000, we analyzed the relationship between the TC genesis over the Northwest Pacific (NWP) and the sea surface temperature anomalies (SSTA) over the Pacific basin. A long-term trend indicated that the highest frequency of monthly TC genesis appeared earlier and the annual genesis sum increased gradually during the last half century with some oscillations. No significant synchronous correlation was found between the NWP TC events and the SSTA over the Pacific basin, while the annual sum of TC genesis was closely related with the SSTA averaged from the first three months (January, February and March) of the year in the equatorial western and eastern Pacific and over mid-high latitudes of the North Pacific. The results implied that there are an interannual El Nio SSTA mode in the equatorial western and eastern Pacific and an interdecadal SSTA mode in the northern Pacific, which affected the TC genesis. A regression analysis between the first three-month SSTA and the annual TC sum based on two time scales was conducted. The correlation coefficient between simulated and observed TC sums reached a high value of 0.77.

关键词： tropical cyclone long-term trend sea surface temperature Pacific.