影响广西的东风波特点

对1980年9月至2003年9月共24a来影响广西的14次东风波天气过程，从其降雨强度、形成特征等作出了统计分析，并从中找出东风波影响广西的预报参考点。     

东风波对江西强对流天气环境条件的影响分析

基于1999—2011年7—9月影响江西的14次东风波过程,统计了东风波的类型及结构特征,利用探空和NCEP再分析资料分析了三种类型东风波对垂直运动、温湿场和稳定度的影响。结果表明:深厚东风波槽前带来弱的上升运动,高层东风波的上升运动位于500 h Pa以上,槽前强对流均在午后发展;大范围强对流对应200 h Pa上鞍型场中的辐散区。中低层东风波和深厚东风波的槽后带来大尺度上升运动,低层东南气流辐合触发对流;大范围强对流对应200 h Pa上南亚高压东侧的辐散区。东风波提供了对流发展的有利环境条件,盛夏大气低层常高温高湿,随着东风波的西移,带来中高层冷扰动以及中低层水汽含量增加,增强了对流不稳定。深厚东风波和高层东风波的槽前、中低层东风波的槽后中层冷扰动区对应低层暖湿区是有利雷暴与强对流发展的区域。高层东风波的冷扰动最明显,其850 h Pa与500 h Pa温度差多在26℃以上,出现8级以上雷雨大风的概率较高;中低层东风波的冷扰动一般较弱,强对流以短时强降雨为主。     

中国南部沿海暴雨东风波特征及SST影响机制研究

分析1999—2013年影响我国南部沿海的东风波,可分为3类:偏南东风波、西行东风波以及近海东风波。太平洋副热带高压是影响3类东风波特征的关键系统,其西伸与北进直接引导东风波路径及活动位置。东风波的分类合成结构特征显示:强涡度中心指示东风波槽中心,强涡度中心通常位于850 h Pa及以下。东风波低层为强辐合场,槽后有整层的垂直上升区。偏南东风波波槽轴线随高度向西倾斜,西行东风波和近海东风波波槽轴线近乎垂直。合成诊断还显示,东风波的海上移动有向SST(Sea Surface Temperature,海表温度)大值趋暖的趋势。数值模拟证实,增强东风波槽前SST暖中心的强度,将引起槽区低层和槽后中层出现负变高中心,同时SST的增温将通过感热与潜热促使东风波槽强度加强,将进一步地增强东风波暴雨强度和雨带的北移。并增强中低层流场的气旋式气流成分,增强低层辐合场,维持深厚垂直上升运动层。典型西行东风波个例分析显示,螺旋度与东风波强度成正比,东风波纬向位温偏差显示东风波在热力场上具有"上暖下冷"的不稳定垂直结构。东风波涡度增强时,扰动动能向分层扰动位能转化。东风波强度减弱时,分层扰动位能向扰动动能转化。     

影响浙闽沿海的两次东风波过程对比分析

利用常规气象观测资料和NCEP1°×1°再分析资料对2001年8月3～4日和2009年9月29日～10月1日发生在浙闽沿海的两次东风波过程进行对比分析.结果表明:前者属于深厚对流层东风波过程,后者则为低层东风波过程.通过对这两次过程的对比分析找出了它们之间的共同点和不同点,而对两次过程动力条件的进一步对比分析,探讨了涡...     

影响肇庆地区两次东风波结构与雨带变化的分析

利用常规观测资料对2010年8月5～6日与2011年7月11～13日盛夏发生在肇庆地区的2次东风波过程的天气形势、物理量特征进行分析,并对其结构与雨带变化进行了对比。结果表明:2次东风波过程是2种不同类型的东风波;地面图上的气流辐合区、物理量要素的变化、850～500 hPa东风波槽线位置及各层风速大小等,与东风波影响的降水区域有密切关系。     

浅析东风波对防城港市天气影响

分析多年影响防城港市东风波天气特征,得出东风波槽不同位置、季节、类型呈现三种不同类型天气特征结论,指出分析东风波类型、位置的方法.     

东风波对成都市天气的影响

东风波是热带天气系统,当它西移时,四川盆地受影响的地区主要在30癗以南 ,30癗以北,若没有西风系统或高原系统配合,一般不受东风波系统的影响,本文讨论东风波对30癗以北成都市天气的影响.     

东风波对成都市天气的影响

东风波是热带天气系统,当它西移时,四川盆地受影响的地区主要在３０°Ｎ以南,３０°Ｎ以北,若没有西风系统或高原系统配合,一般不受东风波系统的影响,本文讨论东风波对３０°Ｎ以北成都市天气的影响     

影响桂东南东风波特征及其概念模型

利用NCEP 2.5°×2.5°风场每6h再分析资料和常规观测资料,分析了近40a(1970.7～2009.9)35次影响桂东南的东风波天气过程。通过降雨强度、雨区分布及系统结构的统计分析,对东风波进行了归类。基于典型东风波过程,运用合成分析方法建立了各类东风波天气概念模型,结合本地预报经验提出了桂东南东风波的预报着眼点。     

影响华南的一次东风波天气过程

通过分析一个影响华南地区的高层东风波个例,得出了这次高层东风波的系统特征:波动系统不够深厚,甚至在低层等压面上分析不出倒槽来;在东风波影响华南前期,高层200～300hPa倒槽气旋性弯曲比较明显,而低层却几乎反映不出;中高层槽线及槽前有正涡度平流,这与云系和雨区分布一致;并指出,分析200～500hPa高空形势、并结合卫星云图,是提前预报这种高层东风波的关键.     

广西县级气象影视服务发展对策研究

在广西气象影视中心2009年6-9月开展的公众气象服务调研评估工作所获得的相关科学数据的基础上,对广西县级气象影视发展状况和影响因素以及集约化效益进行科学分析,提出了进一步推动集约化发展、多级气象影视部门合作共赢的思路。     

广西雷电活动的方向性变化及其应用

通过对广西 90个气象台站 196 1- 1998年的雷电记录进行统计分析 ,得出 2～ 6月份广西大多数地方的雷电活动以 SW方向最为频繁 ,7～ 9月则以 SE方向最多 ;讨论应用雷电频率、土壤电阻率、相对高度 3个要素定性判断雷击危险性问题。     

全球500kPa角动量与EP通量的季节变化

利用ＥＣＭＷＦ提供的９ａ（１９８Ｏ－１９８８）资料，从定性和定量角度分析５００ｈＰａ全球东西风带的角动量和ＥＰ通量的季节过渡。结果发现：不仅角动量存在明显的季节性急变，而且反映波活动的ＥＰ通量也存在相应的季节性急变。另外，季节性急变的发生时间在东西风带亦有所不同。     

Case Study on the Impact of the Vortex in the Easterlies in the Tropical Upper Troposphere on the Western Pacific Subtropical Anticyclone

By employing the NCEP/NCAR reanalysis data （1000-10 hPa, 2.5°×2.5°）, the impact of the vortex in the easterlies （EV） over the tropical upper troposphere on the zonal movement of the western Pacific subtropical anticyclone （WPSA） during 19-25 June 2003 is analyzed in this paper. It is shown that the EV can extend from middle troposphere to the height of 50 hPa, reaching a maximum at 200 hPa. The vertical thermal distribution appears to be ＂warmer in the upper layer and colder in the lower layer＂. The WPSA retreats eastward abnormally when the EV and the vortex in the westerlies （WV） encounter around the same longitude while they move toward each other. It is also shown that the vorticity variation extends from the troposphere to the height of 50 hPa, with the most prominent change occurring at 200 hPa by the diagnostic analyses of the vertical vorticity equation. The WPSA appears to retreat abnormally eastward while the negative/positive vorticity change becomes stronger near the east/west side of the EV, and the areas with positive vorticity tendency both in the EV and WV join together into one belt along 130°E during the process of the EV and the WV moving toward each other. In the vorticity equation, the positive contribution caused by the horizontal advection term is the maximum, and the minimum is caused by theβ effect. It is also found that enhanced horizontal vorticity advection andβ effect, as well as the ＂barotropic development＂ resulted from the in-phase superposition of the southerly and the northerly winds in the easterlies and westerlies near 130~E, are in agreement with the WPSA eastward retreat.     

Medium-range oscillations in the summer tropical easterlies at 200 hPa

By the use of space-time spectral analysis and band-pass filter, some of the features of the medium-range Oscillations in the summer tropical easterlies (10oS-20o) at 200 hPa are investigated based on a two-year (1980 and 1982) wind (u, v) data set for the period from May to September. Space-time power spectral analysis shows that the total energy of the westward moving waves was the largest and that of the standing waves and eastward moving waves was relatively small in the 200 hPa easterlies; the total energy of the eastward moving waves was at minimum at 10oN. Three kind of the medium-range oscillations with about 50 day, 25 day and quasi-biweekly periods were found in the easterlies, which all show a remarkable interannual variation and latitudinal differences in these two years. The wave energy of zonal wind is mainly associated with the planetary waves (1-3), which all may make important contributions to the 50 day and 25 day oscillations in different years or different latitudes. The quasi-biweekly oscillation is mainly related to the synoptic waves (4-6). In equatorial region, the 50 day oscillation was dominant with a eastward phase propagation in 1982 while the dominant oscillation in 1980 was of 25day period with a westward phase propagations in 1980. Both of them are of the mode of zonal wavenumber 1. Strong westward 50 day oscillation was found in 10oN-20oN in these two years. Regular propagations of the meridional wind 50 day oscillation were also found in the easterlies.The 50 day and 25 day oscillation of zonal wind all demonstrate southward phase propagation over the region of the South Asia monsoon and northward phase propagation near interational date line, where are the climatic mean position of the tropical upper-tropospheric easterly jet and the tropical upper tropospheric trough (TUTT), respectively.     

决定大氣環流的基本因子

大氣環流一般理解為大氣准常定的平均狀態,也有理解為某一段時間內大氣中大型形勢的變化过程。其实,这兩种正是大氣環流一個問題的兩种表現,它們是密切的联系着,它們是一個整体。大氣環流顯然是一個錯綜複雜的問題。但自然界中現象的發生,必然存在一些客观的因子,探討其客观因子,对於大氣環流問題的認識与解决定有很大幫助的。本文所討論,就是对於决定大氣環流的因子提供一些具体意     

Equatorial Atlantic variability and its relation to mean state biases in CMIP5

Coupled general circulation model (GCM) simulations participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) are analyzed with respect to their performance in the equatorial Atlantic. In terms of the mean state, 29 out of 33 models examined continue to suffer from serious biases including an annual mean zonal equatorial SST gradient whose sign is opposite to observations. Westerly surface wind biases in boreal spring play an important role in the reversed SST gradient by deepening the thermocline in the eastern equatorial Atlantic and thus reducing upwelling efficiency and SST cooling in the following months. Both magnitude and seasonal evolution of the biases are very similar to what was found previously for CMIP3 models, indicating that improvements have only been modest. The weaker than observed equatorial easterlies are also simulated by atmospheric GCMs forced with observed SST. They are related to both continental convection and the latitudinal position of the intertropical convergence zone (ITCZ). Particularly the latter has a strong influence on equatorial zonal winds in both the seasonal cycle and interannual variability. The dependence of equatorial easterlies on ITCZ latitude shows a marked asymmetry. From the equator to 15°N, the equatorial easterlies intensify approximately linearly with ITCZ latitude. When the ITCZ is south of the equator, on the other hand, the equatorial easterlies are uniformly weak. Despite serious mean state biases, several models are able to capture some aspects of the equatorial mode of interannual SST variability, including amplitude, pattern, phase locking to boreal summer, and duration of events. The latitudinal position of the boreal spring ITCZ, through its influence on equatorial surface winds, appears to play an important role in initiating warm events.     

热带东风急流的气候学和中期振荡

本文用13年夏半年(5—10月)月平均风场和两年逐日风场资料研究了200hPa南亚热带东风急流的气候学特征和中期振荡过程。研究表明,南亚夏季热带东风急流显著的非季节性变动和年际差异与低纬对流层高层大尺度环流变化和南亚夏季风活动密切相关,相对于多年平均而言,存在5类异常的东风急流。 各种分析表明,热带东风带存在三种主要的中期振荡。准50天周期振荡与夏季南亚对流层上部大尺度散度场的变化相关联,表现为十分显著的向南的位相传播。准50天和25天振荡均存在显著的年际变化。准50天周期振荡系统性不强的年份,准25天周期振荡是低纬行星波的主要振荡,在东风急流区除表现为系统性向西传播外也表现为向南的位相传播。准双周振荡在东风带一般向西传播。      

东西风廓线特征与大气运动平衡态定常波的相关关系及共振条件的研究

本文采用简化数学模型探讨了东、西风廓线特征与外源强迫下大气环流平衡态定常波结构的相关关系。文中采用实际观测资料研究了西风廓线特征与大气环流型季节特征之间的联系。研究表明,西风廓线冬、夏季节差异与中、高纬度西风槽“冬三夏四”波数差气候特征有关,且低纬强东风切变可作为赤道东风波周期振荡成因之一。冬夏西风廓线季节特征可导致大地形强迫效应、海陆加热因子影响作用的显著季节差异。研究还揭示了大气环流型优势波转换的基流特征影响效应,并导出了流场与纬向加热强迫源共振状态的西风廓线特征函数与临界曲线。     

Influence of the warm pool and cold tongue El Niños on the following Caribbean rainy season rainfall

Caribbean rainfall and associated regional-scale ocean–atmosphere anomalies are analyzed during and after warm pool (WP) and cold tongue (CT) El Niño (EN) events (i.e. from the usual peak of EN events in boreal winter to next summer from 1950 to 2011). During and after a CT event, a north–south dipolar pattern with positive (negative) rainfall anomalies over the northern (southern) Caribbean during the boreal winter tends to reverse in spring, and then to vanish in summer. On the contrary, during and after a WP event, weak rainfall anomalies during the boreal winter intensify themselves from spring, with anomalous wet conditions over most of the Caribbean basin observed during summer, except over the eastern coast of Nicaragua and Costa Rica. The Caribbean rainfall anomalies associated with WP and CT events are shaped by competition between at least four different, but interrelated, mechanisms; (1) the near-equatorial large-scale subsidence anomaly over the equatorial Atlantic linked to the zonal adjustment of the Walker circulation; (2) the extra-tropical wave-like train combining positive phase of the Pacific/North American mode and negative phase of the North Atlantic Oscillation; (3) the wind-evaporation-sea surface temperature (SST) positive feedback coupling warmer-than-normal SST with weaker-than-normal low level easterlies over the tropical North Atlantic; and (4) the air-sea coupling between the speed of low level easterlies, including the Caribbean low level jet, and the SST anomaly (SSTA) gradient between the Caribbean basin and the eastern equatorial Pacific. It seems that Caribbean rainfall anomalies are shaped mostly by mechanisms (1–3) during CT events from the boreal winter to spring. These mechanisms seem less efficient during WP events when the atmospheric response seems driven mostly by mechanism (4), coupling positive west-east SSTA gradient with weaker-than-normal low level easterlies, and secondary by mechanism (3), from the boreal spring to summer.