一次温带气旋的同化试验

温带气旋在浙江海域入海发展形成的瞬时大风和大浪常常会造成船只倾覆、人员伤亡等灾情。本文采用WRF中尺度数值模式对一次入海温带气旋过程进行3个试验分析,包括试验一(不同化任何资料)、试验二(将未经质量控制的云迹风资料全部放入模式同化)和试验三(将经质量控制以后的云迹风资料放入模式同化)。通过对高度场和风场等的模拟,并与实况对比,表明将经质量控制的云迹风资料放入模式可以较大程度改进温带气旋的模拟结果,为提高影响浙江海域的温带气旋预报的准确率提供一定参考。     

影响浙江海域的温带气旋研究

统计了44年来影响浙江海域的温带气旋及特征,并采用WRF中尺度数值模式对一次影响浙江海域的温带气旋的发生发展过程进行云迹风同化试验。通过分析时空变化特征和一次温带气旋发展过程中高低空的物理场变化,寻找温带气旋预报的着眼点。     

A preliminary analysis of physical mechanism of transformation process from a landed typhoon into an extratropical cyclone

A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:The changes of kinetic energy are mainly attributed to the generation due to non-divergent wind. During the early stage of the typhoon landing, there exits only a small quantity of kinetic energy exchanging with the environment. And after it is transformed into an extratropical cyclone, a large amount of kinetic energy is exported from the system toward the environment.The horizontal and vertical flux-divergence terms of eddy available potenlial energy are the prominent sinks in the budgets of eddy kinetic energy. The generations of eddy kinetic energy due to both the barotropic and baroclinic processes are source terms. The former is remarkable during the initial stage. But after the depression is transformed into an extratropical cyclone, the roles of the generation by the barotropic and baroclinic proc     

2016年10月11—19日东南太平洋一次温带气旋过程分析

利用美国国家环境预报中心发布的FNL资料、红外卫星云图资料和船测资料,对2016年10月17—19日某船舶在东南太平洋遭遇的一次温带气旋过程进行研究,以此为大洋航线上温带气旋预报保障能力提高积累经验。结果表明:(1)温带气旋A由绕极槽北伸切断发展而来,自西向东移动过程中在南太平洋大洋中部与另一气旋B合并加强对船舶航行造成影响;(2)气旋A初生阶段,大气低层旋转程度较强;成熟发展阶段在近地面、大气上层旋转程度较强;当气旋B初生发展时,气旋A中心附近自500 hPa以下为绝对涡度小值区,其上为绝对涡度大值区,绝对涡度垂直轴线向近B一侧倾斜;(3)槽后及气旋中心附近正涡度平流与槽前随高度增强的暖平流共同促使气旋发展。     

一种普适性的加权热带气旋风场重构方法

台风浪模拟是海洋和海岸工程中开展重现期波浪推算的关键环节。本文在系统分析历史热带气旋近中心最大风速、大风风圈以及CCMP风场特征的基础上,提出了一种热带气旋影响范围计算方案,改进了加权热带气旋风场重构方法。以该方法重构的热带气旋风场为驱动,采用WAVEWATCH Ⅲ模型模拟了南海28次台风浪过程,并用南海北部88个站次的风、浪观测资料对重构后的风场及模拟浪高进行检验。检验结果显示:风速(台风浪高)的重构值(模拟值)与观测值吻合良好,改进后的加权热带气旋风场重构方法有较强的普适性。     

热带气旋过境期间黑潮流轴变化的初步分析

利用卫星高度计资料分析了热带气旋"艾碧"(Abe,9315)、"贝姬"(Becky,9316)、"莫拉克"(Morakot,0309)和"茉莉"(Melor,0319)对吕宋海峡及其附近海域黑潮流轴的影响。研究表明:1)吕宋海峡附近海域黑潮流轴容易受到热带气旋的影响而发生一定的变化。2)在热带气旋的作用下,黑潮流轴因中尺度涡的变异而变化;当吕宋海峡东侧的暖涡西移时,将使黑潮的流轴向西弯曲,有利于黑潮在该处的入侵。     

山东近海温带气旋强南向大风的特征分析

利用站点观测、历史天气图和NCEP/NCAR的再分析资料,对近40年(1971-2010年)山东近海强南向大风的气候特征和温带气旋造成强南向大风的因素进行了分析。通过统计山东沿海6个代表站点40年的7级以上南向大风,表明:近40年山东近海强南向大风年日数基本呈逐渐减少的趋势,1991年以后年大风日数明显减少,强南向大风主要出现在春季和夏初;统计2000-2010年山东近海强南向大风的个例,发现,温带气旋造成山东近海强南向大风可分为北方气旋(蒙古气旋、黄河气旋)和南方气旋(江淮气旋、黄淮气旋)。分析两类气旋造成强南向大风的因素表明:气压梯度、850 hPa及以下急流和850 hPa暖平流是造成强南向大风的重要因子,3小时变压、500 hPa高空急流和暖平流是次要因子,但气旋在地面气压场配置、3小时变压分布、低空暖平流强弱等方面存在差异。     

A WKB analysis of the surface signature and vertical structure of long extratropical baroclinic Rossby waves over topography

WKB theory has been used recently to construct global approximations of purely periodic long extratropical baroclinic Rossby waves in a continuously stratified ocean, with the goal of building a global theoretical framework that can serve to interpret observed features of the waves, such as sea surface height wave activity and anomalous propagation. This study adopts the same approach in the idealized context of an ocean with constant buoyancy frequency N and longitudinally varying Gaussian topography, to gain insight into issues that have received little or no attention so far, namely: (a) the nature of the links between the vertical structure of the wave field and its surface signature, and the extent to which constraints on the interior dynamics can be derived solely from observing the surface; (b) which of the phase/amplitude variations determine the visual impression of westward propagation, addressed by constructing longitude/time plots of the signal in the attempt to mimic more closely the way the satellite SSH data of TOPEX/Poseidon are analyzed; (c) the validity and accuracy of the classical leading order WKB theory, addressed by estimating the residual a posteriori by computing the next-order term of the formal WKB series expansion. To a lesser extent, this also serves to assess the validity of the planetary geostrophic equations used to describe the dynamics of long Rossby waves.The main results are that: (a) faster propagation is unambiguously related to the surface intensification of the waves, while slower propagation is associated with a vertical structure intermediate between that of the first and second standard baroclinic modes; (b) westward propagation is dominated by the phase variations; (c) the residual is inversely proportional to the frequency (or equivalently the wavelength by dividing by the phase speed), and is found to vary strongly with position. The hilltop is where the residual is the highest, and hence where WKB is the most likely to breakdown, in agreement with recent published predictions of mode conversion theory in a two-layer model setting.     

基于人工神经网络的台风浪高快速计算方法

采用2010—2017年南海5个浮标波高观测资料和中国气象局热带气旋最佳路径集中的热带气旋参数, 基于前馈型误差反向传播(Forward Feedback Back Propagation, FFBP)神经网络(Artificial Neural Network, ANN)方法, 分别建立了各浮标站的台风浪高快速计算模型。研究显示, 基于热带气旋中心坐标、中心最低气压、近中心最大风速、热带气旋中心与浮标之间的距离和方位4个参数建立的神经网络模型经反复训练后, 模型输出结果可以很好地拟合观测数据, 各浮标有效波高计算值与观测值的均方根误差小于0.3m, 平均相对误差为5.78%~7.23%, 相关系数大于0.9, 属高度相关。独立测试结果显示, “山竹”( 国际编号: 1822)影响期间有效波高最大值的神经网络模型预报结果与观测值基本吻合, 相对误差为-31.06%~0.98%, 但计算的最大值出现时间和观测情况不完全一致。该计算方法可应用于热带气旋影响期间的有效波高最大值计算, 因而在海洋工程领域和海洋预报领域具有应用前景。     

近五十年登陆海南省的热带气旋统计特征分析

利用《热带气旋年鉴》等资料,统计分析1964—2013年登陆海南省的热带气旋(TC)特征,着重分析TC的年、月、强度、路径、登陆点等特征,为做好海南省海洋预报提供更好的依据。分析结果表明:平均每年登陆海南省的TC有1.7个,登陆频数的年代际呈现增减阶段性转换的变化趋势,登陆频数偏多与偏少年代各约持续25—30 a;TC登陆海南省的频数有明显的季节性特征,夏季和秋季TC登陆频繁,主要集中在7、8、9月,占总登陆频数的62%,其次是10月份,占17.4%,春季TC登陆频数较少,冬季没有TC在海南省登陆;登陆海南省的TC包括热带低压(TD)、热带风暴(TS)、强热带风暴(STS)、台风(TY)、强台风(STY)及超强台风(Super TY),其中STS与TY登陆频数最多,分别占登陆总数的25.2%和32.1%,STS主要集中在7、8月份,占STS总数的77.2%,TY主要集中在9、10月份,占TY总数的46.4%;登陆海南省的TC主要路径是西行型及西北型,所占比率分别为33.3%和31%;在海南省登陆的TC概率最高登陆点是文昌,其次是万宁和三亚,概率最小的是陵水。     

基于卫星云图的轮廓法自动识别热带气旋研究

以卫星云图的热带气旋云系为研究对象,基于Canny边缘检测、Contour轮廓提取等方法,研究了通过图像的形状特征和范围大小对热带气旋云系进行自动识别,得到了较好的效果。这种方法有助于提高热带气旋云系识别的自动化程度,实现热带气旋的自动跟踪,从而为热带气旋的预报提供了便利。     

Who's who in the Kenai River Fishery SES: A streamlined method for stakeholder identification and investment analysis

The Kenai River Fishery is a unique social–ecological system (SES) with nearly 50 federal, state, local, and nonprofit groups influencing its political, ecological, and social structure. While ecological data exists for this fishery, the complexity of its stakeholder relationships has not been investigated. Stakeholder interactions can directly influence how science is integrated into management decisions and therefore affect the adaptive capacity of SES, such as the Kenai River Fishery. Drawing from the existing stakeholder literature, this methods identifies and ranks the key SES stakeholders and describes their roles. This study approached the question of which stakeholders should be included in a future SES adaptive capacity study by (1) identifying the key stakeholders within the Kenai River Fishery, (2) ranking each stakeholder’s investment within the fishery using eleven categories of interaction, and (3) using these eleven categories to characterize each stakeholder's role within the SES. The largest number of stakeholders fall into the secondary investment category, showing that a relatively small number of resource managers are interacting with a large number of diverse nonprofit organizations. The top ranking stakeholders in this study will be invited to attend participatory scenarios workshops that will build the foundation for a deeper scenarios-based analysis of SES adaptive capacity.     

On the relation of the number of extratropical cyclones to their sizes

Extratropical cyclones were identified on the basis of sea level pressure NCEP/NCAR reanalysis data for the Northern Hemisphere from 1948 to 2004. Cyclone positions were determined with a time interval of 6 h. Cyclone sizes were obtained with the use of a numerical scheme based on a rotation of the spherical coordinate system such that the pole of the new coordinate system coincided with the cyclone center. Cyclone sizes were determined at each step of the trajectory. The last closed isobar was assumed to be the outer boundary of the cyclone. The pressure deficit in the cyclone center was regarded as a characteristic of the intensity of a synoptic formation. The interrelation between the number of cyclones and their sizes was estimated for all extratropical cyclones of the Northern Hemisphere regardless of the stage of their development. The number of cases being analyzed is 1.5 × 10⁶. Cyclone areas vary from 0.13 × 10⁶ to 6.4 × 10⁶ km², and 80% of extratropical cyclones have an intensity of 1–15 hPa. The distribution of the number of cyclones depending on their intensities is shown to be of an exponential character. The distributions of the number of cyclones were approximated with a very high accuracy, so that the regularities obtained are very stable during the past several decades.     

热带气旋在东海的活动及其灾害分析

本文根据1949～1989年热带气旋历史资料,对影响东海的热带气旋进行了统计分析,结果表明,热带气旋在东海的活动相当频繁,特别是7、8、9三个月;热带气旋逐年出现个数有明显的年际波动和季节性变化;进入东海的热带气旋大致分为七类路径,不同路径的热带气旋对东海沿岸地区造成不同程度的危害,其灾情以具体实例作了阐述。     

浙江沿海2010“10.25”温带风暴潮灾害特征及成因分析

2010年10月25—29日,浙江省沿岸遭受了本海区近10年来最强温带风暴潮袭击,浙江北部沿海部分岸段出现超过当地警戒潮位的高潮位,宁波镇海、舟山定海和沈家门部分沿岸地区出现漫滩和内涝等险情。本文根据实况天气图、实况观测资料和实况分析资料,分析了10.25温带风暴潮的成因、特点,为今后预报此类风暴潮提供一些可借鉴的预报经验。     

热带外太平洋通过海洋过程对热带太平洋的影响

利用MOM2海洋环流模式分别研究了年际和年代际尺度上热带外太平洋通过海洋过程对热带太平洋的影响.利用1945~1993年COADS资料的表面通量强迫海洋模式,积分46 a作为模式控制试验.取热带外太平洋海表面强迫为气候值做敏感性试验.将控制试验结果减去敏感性结果就可以得到热带外太平洋通过海洋过程对热带太平洋的影响.结果表明,年际尺度上,主要是海洋波动过程起作用,但总的海洋过程的影响较小.年代际尺度上,主要是副热带环流输送起作用,其中包括平均环流输送的温度异常以及异常环流输送的平均温度,并且后者贡献相对较大.年际和年代际尺度上,热带太平洋的温度异常主要发生在密度跃层附近.研究发现热带外南太平洋对热带和热带外太平洋之间的水量交换有影响,而热带外北太平洋的影响较弱.