登陆广东省热带气旋的奇异谱分析

利用奇异谱方法(SSA方法)分析登陆广东省的热带气旋的演变规律，发现年登陆的热带气旋数存在明显的8年、准3年的周期振荡；登陆珠江口以西的热带气旋数存在12年、准2年的周期振荡。把产生热带气旋的源地——西北太平洋划分为8个海区，对每个海区的海表温度进行奇异谱分析，结果显示NIN0西区和暖池海区分别存在8年和3年的准周期振荡及12年和2年的周期振荡，这很可能是登陆广东的热带气旋产生的物理原因。最后结合最大炳谱方法(SSA—MEM)做出登陆广东省的全年和登陆珠江口以西的热带气旋趋势预报，其效果较理想，在短期气候预测业务中有一定的参考价值。     

ANALYSIS OF CAUSATION OF ABNORMAL MOTION OF LANDING TROPICAL CYCLONES IN GUANGDONG

1 INTRODUCTION It is doubtless that TCs making landfalls on Guangdong are one of the important aspects of the research on and prediction of short-term climate changes for the province. With regard to the climate patterns of TCs motion and factors governin…     

我国近百年气温变化的奇异谱分析

用奇异谱方法分析我国近百年平均气温的准周期性,结果表明：我国平均气温的年际变化以２～３ａ周期振荡为主,同时１ａ左右的准同期振荡也较强,和同期北半球平均气温的准周期性有差异,不过它们的准１ａ周期振荡随时间的阶段性变化特征非常相似。将我国大致分成７个区域,对７个区域代表站气温进行奇异谱分析,结果表明：各区气温的准周期振荡及其随时间的变化互不相同。华北、东北、西北、和青藏高原４区气温以１ａ周期振荡最为显     

华东登陆热带气旋若干回波参数的分析应用

新一代天气雷达在台风监测及短期临近预警中的作用越来越大,但当前CINRAD雷达针对台风的监测产品仍不能满足需求。通过对近年来登陆浙江的热带气旋雷达回波参数的分析和计算发现,监测、诊断近海台风,除了考虑回波的强度、大小、高度及结构等传统因素外,以雷达资料计算台风的最大风圈半径、切向旋转环流速度等参数,可便捷快速地分析台风的强度及影响范围;台风环平均强度(或台风环平均降水率)在登陆前后变化明显,环状平均降水主峰值的半径均呈现增大态势,主峰极值与次峰极值在量级上的差距加大更为显著。研究表明,当台风临近时,利用雷达密切监测回波的演变、及时提取和分析有关参数,对台风研究及提升台风临近预警能力都具有重要意义。     

AN ANALYSIS ON INTERDECADAL VARIATIONS OF TROPICAL CYCLONE PRECIPITATION IN GUANGDONG PROVINCE OF CHINA

The interdecadal variations of tropical cyclones(TCs) and their precipitation over Guangdong Province are investigated using the observational data of TCs and precipitation from 26 observational stations in the province from 1951 to 2005.The results show that the TCs precipitation shows an oscillation with a peak value of about 25 years,with both the numbers of the Guangdong-influencing TCs and TCs formed in the western North Pacific oscillating with a peak value of about 23 years.The correlations are highly positive between the interdecadal variation of TC precipitation over the province and these numbers.The interdecadal variation of TC precipitation in the province shows significant negative correlations with the interdecadal variation of annual mean SST in some parts of the western North Pacific and the interdecadal variation of annual mean 500 hPa geopotential heights in some parts of the middle and high latitudes over the North Pacific.In general,there are high mean SSTs on the equator from central to eastern Pacific,low mean SSTs in the middle and high latitudes over the North Pacific and a main strong East Asian trough over the North Pacific in the period of less TC precipitation as compared with the period of more TC precipitation over the province.     

广东热带气旋降水年代际变化特征的分析

采用1951—2005年热带气旋和广东省26个测站降水的观测资料,分析了广东热带气旋及其降水的年代际变化特征。结果表明:广东热带气旋降水存在峰值为25年左右的振荡周期,影响广东的热带气旋个数和西北太平洋上热带气旋的形成个数都存在峰值为23年左右的振荡周期;广东热带气旋降水的年代际变化与影响广东的热带气旋个数和西北太平洋上热带气旋的形成个数存在高度正相关;广东热带气旋降水的年代际变化与西太平洋部分区域的年平均SST的年代际变化和北太平洋中高纬部分地区的年平均500 hPa位势高度的年代际变化存在显著的负相关;广东热带气旋降水偏少时期与降水偏多时期相比,一般赤道中、东太平洋的平均SST相对较高,而北太平洋中纬度地区的平均SST相对较低,北太平洋上的东亚大槽相对较强。     

PRELIMINARY ANALYSIS OF EFFECTS OF OLR FIELDS ON ANNUAL FREQUENCY OF TROPICAL CYCLONE IN FUJIAN

Outgoing Longwave Radiation (OLR) has been shown to play an important role in climatic diagnosis and long-term prediction and research. With the OLR data 1974 ~ 1997 as observed by satellites, the characteristics are computed. The results are used to depict the location and intensity of the subtropical high in the study of the relationship between the annual frequency of tropical cyclones affecting the Fujian province and ITCZ / subtropical high. It is shown that in years of fewer (more) tropical cyclones, the ITCZ is southward (northward) located with weaker (stronger) intensity, and the subtropical high is southward (northward). As shown in the relationship between the anomalous years of tropical cyclones and characteristics of preceding OLR fields, the OLR anomalies are just oppositely distributed in the Pacific Ocean for years of more (fewer) tropical cyclones. In other words, the years of fewer (more) tropical cyclones are associated with positive anomalies of OLR in the tropical west Pacific but negative (positive) anomalies in the equatorial central and eastern Pacific. It is hoped that our study be setting foundation for short-term climatological prediction of tropical cyclones.     

大气季节内振荡对热带气旋活动影响的研究进展

近30年来，大气季节内振荡对热带气旋活动影响的研究已逐渐成为人们关注的焦点，并取得了显著的进展。就大气季节内振荡对热带气旋生成、路径及登陆的影响进行概述，并揭示了这种影响的主要机制。同时回顾了与季节内振荡密切相关的季风槽活动对热带气旋的影响。在此基础上简单讨论了该领域中存在的问题及未来研究前景，并提出当前该研究领域中一些亟需研究的科学问题。     

ANALYSIS OF INDICES FOR SEVERE CONVECTIVE WEATHER UNDER THE INFLUENCE OF TROPICAL CYCLONES IN JIANGSU

By statistical research on the occurrence pattern of severe convective weather in Jiangsu province under the influence of tropical cyclones within a 10-year period (from 2001 to 2010), this paper discovers that among different severe convective weather, the occurrence frequency of short-range heavy precipitation is the highest, thunderstorms and gales come in second, and general thunderstorms rarely happen, while hailstorms and tornadoes never occur. The statistical results also showed that within the research period there are 21 tropical cyclones (TCs) affecting the Jiangsu area and most of them are in the stage of weakening to tropical depressions. Moreover, through studying indices for relevant cases of severe convection, it is discovered that their thresholds are lower than that of previous research, which indicated that convective instability and energy accumulation can easily lead to severe convective weather eventually due to the influence of TCs.     

INTRASEASONAL OSCILLATIONS IN ASIA TO WESTERN PACIFIC REGION IN BOREAL SUMMER: CONTRASTIVE ANALYSIS FOR ACTIVE AND INACTIVE YEARS OF TROPICAL CYCLONES

Comparative analysis is carried out by using finite-domain power spectrum and lagged regression methods for the propagating characteristics and air-sea interaction processes of intraseasonal oscillations (ISOs) in the Asia to western Pacific (AWP) region during the boreal summer between the active and inactive tropical cyclone (TC) years from 1979 to 2004.The results show as follows.(1) There exist more significant eastward propagating characteristics of the ISO in the active TC years over the whole AWP region.The ISOs of convection propagate zonally with more eastward extension in the years with active tropical cyclone activities,during which the 20-60-day period is strengthened,western Pacific becomes an area with evident characteristics of the propagation that is closely related to TC activities.(2) The air-sea interaction processes are the same in both active and inactive TC years,and the energy exchanges between the air and the sea play a role in maintaining the northwestward propagation of ISOs.(3) The air-sea interaction is more intensive in the active TC years than in the inactive ones.It is particularly true for the latent heat release by condensation as the result of convection,which may be one of the reasons resulting in significant differences in characteristics of ISOs between the active and inactive TC years.     

THE OBJE CTIVE ANALOGUE PREDICTION MODEL FOR TROPICAL CYCLONE TRACK WITH COMPREHENSIVE ASSESSMENT OF THE ENVIRONMENT

An objective analogue prediction model for tropical cyclone (TC) track is put forward that comprehensively assesses the environmental field. With the parameters of the tropical cyclone and environmental field at initial and future time, objective analogue criteria are set up in the model. Analogous samples are recognized by comprehensive assessment to historical TC cases for similarity with multivariate criteria,using non-linear analogue indexes especially defined for the purpose. When the historical tracks are coordinateconverted and weighted with reference to analogue indexes,forecast tracks are determined. As shown in model verification and forecast experiments, the model has forecasting skill.     

西北太平洋暖池热状态对热带气旋活动的影响

研究1959-2003年西北太平洋热带气旋与暖池热状况的联系。结果发现暖池次表层海温与生成的台风个数具有显著相关,当暖池处于热状态时,台风偏少,生成热带风暴的位置偏向于靠近大陆的西北侧,且以西行路径为主,因此对我国的影响较为频繁。而暖池处于冷状态时,生成于西北太平洋东南侧的台风较为频繁,西北向移动至日本东南侧易于发生东北的转向。另外,对暖池冷暖状态年的环流合成发现,海表温度不是影响热带气旋年际数量异常的主要因子,而是由大气环流所引发的动力因素起决定作用。当暖池暖状态时,季风槽东端位置偏西北,对应于低层涡度和高层散度为正距平。引发中层垂直上升运动异常。有利于热带气旋在西北侧海域生成。此时500hPa风场以东风距平为主,且西北太平洋南北侧分别为西风和东风垂直切变距平。而暖池处于冷状态时,东亚季风槽东扩,使得西北太平洋东南侧产生有利于气旋生成的环流背景,同时东亚大槽加强,中层西南风易引导热带气旋东北转向,西北太平洋南北侧分别为东风和西风垂直切变距平。     

THE STRUCTURE OF TROPICAL CYCLONE BY TOVS AND ITS APPLICATION IN NUMERICAL WEATHER PREDICTION

The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000. Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential height field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the geopotential height field between low values at low levels and high values at high levels. It is especially noted that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the tropical cyclone. The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS performs better in coordinating with the environment and predicting the track of the tropical cyclone. The demonstration is two-fold — the structure of the typhoon BOGUS is such that it means much in the track prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the foundation for modification and evolution of typhoon BOGUS.     

COMPARISON OF SOME TROPICAL CYCLONE DATASETS AND CORRECTION OF YEARBOOK DATA

This is a study to compare three selected tropical cyclone datasets separately compiled by CMA Shanghai Typhoon Institute (CMA_SHI), the Joint Typhoon Warning Center (JTWC), and the Japan Meteorological Agency (JMA). The annual frequencies, observation times and destructive power index as the characteristic quantities are investigated of the tropical cyclones over the western North Pacific. The comparative study has resulted in the following findings: 1) Statistical gaps between the datasets compared are narrowing down as the intensity of tropical cyclones increases. 2) In the context of interdecadal distribution, there is for the 1950s a relatively large gap between the datasets, as compared with a narrowed gap for the period from the mid 1970s to the 1980s, and a recurring widened gap for the mid and late 1990s. Additionally, an approach is proposed in the paper to correct the wind speed data in the TC Yearbook.     

DYNAMIC ANALYSIS OF INHERENT CAUSES FOR DEVIATION OF TROPICAL CYCLONE TRACKS

To have a clearer picture of mechanisms responsible for the deviation of tropical cyclone (to be simplified as TC hereafter) tracks, the current work assumes the TC as a circular vortex with a radius of R. A general motion equation of TC is then determined by averaging its horizontal motion equation over the sentire region of TC. In the meantime, with the moving track of TC assumed as a characteristic arc, the curvature equation is derived for the track of movement and patterns of its deviation due to TC structure and variation are discussed. The result shows that the scale, size, maximum wind speed and radius are factors causing the deviation of TC tracks. In addition, asymmetric structure of TC is also important for the deviation of tracks. The results, achieved with hypothesis, agree with facts in some cases but disagree with them in others, which are to be verified with more observations or numerical simulations.     

广东热带气旋年际变化的小波分析

利用《台风年鉴》资料，分析了1951－1999年登陆或严重影响广东的热带气旋的年频数和初旋登陆日期的气候规律。除了利用一般的统计方法以外，还利用近年来分析时间序列比较新的方法，即小波分析。通过对MHAT和MORLET两个小波函数进行分析，分析比较了两个不同小波在其他条件相同情况下的变换结果，分析指出MORLET小波的方差能够比较好的显示出主要的周期，周期－时间序列图可以体现出在各个时段的主要影响周期，MORLET的周期－时间序列图与原序列相比，有较小的飘移现象：MHAT小波虽然没有这种飘移现象，但是其方差的高频部分掩盖了主要周期，使得主要周期与MORLET小波相比方差没有那么明显。同时对放大因子a的两种不同取法做了比较，发现利用a取为2的指数的方法选取a比一般连续的选取a在方差上更能体现主要的周期。年频数的初旋日期的周期分析发现周期分析提取的主要周期与小波变换后得到的主要周期类似。     

SURFACE OBSERVATIONS IN THE TROPICAL CYCLONE ENVIRONMENT OVER THE SOUTH CHINA SEA

In this paper,the observational data from Marine and Meteorological Observation Platform(MMOP)at Bohe,Maoming and buoys located in Shanwei and Maoming are used to study the characteristics of air-sea temperature and specific humidity difference and the relationship between wind and wave with the tropical cyclones over the South China Sea(SCS).The heat and momentum fluxes from eddy covariance measurement(EC)are compared with these fluxes calculated by the COARE 3.0 algorithm for Typhoon Koppu.The results show that at the developing and weakening stages of Koppu,both these differences between the sea surface and the near-surface atmosphere from the MMOP are negative,and data from the buoys also indicate that the differences are negative between the sea surface and near-surface atmosphere on the right rear portion of tropical cyclones(TCs)Molave and Chanthu.However,the differences are positive on the left front portion of Molave and Chanthu.These positive differences suggest that the heat flux is transferred from the ocean to the atmosphere,thus intensifying and maintaining the two TCs.The negative differences indicate that the ocean removes heat fluxes from the atmosphere,thus weakening the TCs.The wind-wave curves of TCs Molave and Chanthu show that significant wave height increases linearly with 2-min wind speed at 10-m height when the wind speed is less than 25 m/s,but when the wind speed is greater than 25 m/s,the significant wave height increases slightly with the wind speed.By comparing the observed sensible heat,latent heat,and friction velocity from EC with these variables from COARE 3.0 algorithm,a great bias between the observed and calculated sensible heat and latent heat fluxes is revealed,and the observed friction velocity is found to be almost the same as the calculated friction velocity.     

ENSO事件影响下登陆中国热带气旋年际变化特征的分位数回归分析

热带气旋每年对我国东南沿海地区造成很大的经济损失和人员伤亡。为了解登陆中国热带气旋的强度、位置和生成频率等特征,基于1949—2018年西北太平洋热带气旋数据,采用分位数回归的方法分析了登陆中国热带气旋活动年际变化特征规律。结果发现:登陆中国热带气旋活动年际变化特征受ENSO事件的影响,El Ni?o年、La Ni?a年和正常年登陆中国热带气旋的最大风速、最长生命期和生成位置的年际变化规律存在较大差异,且这种差异程度和热带气旋强度有关;此外,在不同的分位数下登陆中国热带气旋活动特征的年际变化趋势系数并不相同。研究结果可以为我国的东南沿海热带气旋数据分析和趋势预测提供有效的参考。      

ANALYSIS OF TROPICAL CYCLONE PRECIPITATION FOR DIFFERENT INTENSITY CLASS IN NORTHWEST PACIFIC WITH TRMM DATA

Combined with TRMM products and Tropical Cyclone (TC) best track data in Northwest Pacific from 1 January 2003 to 31 December 2009, a total of 118 TCs, including 336 instantaneous TC precipitation observations are established as the TRMM TC database, and the database is stratified into four intensity classes according to the standard of TC intensity adopted by China Meteorological Administration (CMA): Severe Tropical Storm (STS), Typhoon (TY), Severe Typhoon (STY) and Super Typhoon (SuperTY). For each TC snapshot, the mean rainfall distribution is computed using 10-km annuli from the TC center to a 300-km radius, then the axisymmetric component of TC rainfall is represented by the radial distribution of the azimuthal mean rain rate; the mean rain rates, rain types occurrence and contribution proportion are computed for each TC intensity class; and the mean quadrantal distribution of rain rates along TCs motion is analyzed. The result shows that: (1) TCs mean rain rates increase with their intensity classes, and their radial distributions show single-peak characteristic gradually, and furthermore, the characteristics of rain rates occurrence and contribution proportion change from dual-peak to single-peak distribution, with the peak rain rate at about 5.0 mm/h; (2) Stratiform rain dominate the rain type in the analysis zone, while convective rain mainly occurred in the eye-wall region; (3) The values of mean rain rate in each quadrant along TCs motion are close to each other, relatively, the value in the right-rear quadrant is the smallest one.     

ANALYSIS OF THE CLIMATIC CHARACTERISTICS OF LANDING TROPICAL CYCLONES IN EAST CHINA

The intensity, landing time, track trend and intensity variation of tropical cyclones (TCs) after landfall are analyzed using the TCs data (of best track from the China Meteorological Administration) between 1949 and 2006 for the western North Pacific and South China Sea. The trend differences of track and intensity between the TCs that directly land in East China and those making the second landfall in East China after landing in Taiwan Island are categorically discussed. The results show that the first kind of landing TCs are more likely to go northward or turn while the second kind of TCs have a larger tendency to keep going northwest. The intensity of the first kind of TCs is more persistent than the second one. There is a higher percentage for the intensity to be weakened significantly if the TCs keep going west to northwest or southwest after landing.