K-MEANS CLUSTERING FOR CLASSIFICATION OF THE NORTHWESTERN PACIFIC TROPICAL CYCLONE TRACKS     

余锦华  郑颖青  吴启树  林金凎  龚振彬 《热带气象学报(英文版)》2016,22(2):127-135

Based on the Joint Typhoon Warning Center (JTWC) best-track dataset between 1965 and 2009 and the characteristic parameters including tropical cyclone (TC) position, intensity, path length and direction, a method for objective classification of the Northwestern Pacific tropical cyclone tracks is established by using K-means Clustering. The TC lifespan, energy, active season and landfall probability of seven clusters of tropical cyclone tracks are comparatively analyzed. The characteristics of these parameters are quite different among different tropical cyclone track clusters. From the trend of the past two decades, the frequency of the western recurving cluster (accounting for 21.3% of the total) increased, and the lifespan elongated slightly, which differs from the other clusters. The annual variation of the Power Dissipation Index (PDI) of most clusters mainly depended on the TC intensity and frequency. However, the annual variation of the PDI in the northwestern moving then recurving cluster and the pelagic west-northwest moving cluster mainly depended on the frequency.  相似文献   

近20 a影响我国台风活动变化趋势   总被引：13，自引：10，他引：3  

李真真  吴立广  刘青元 《气象科学》2016,36(6):752-759

利用最新定义的气旋活动指数CAI(Cyclone Activity Index)分析影响我国台风活动近20 a的变化趋势及其可能原因。分析发现,影响我国的台风频数自1996年以来显著减少,主要表现为南方沿海地区热带气旋影响减小,三亚和海口更呈显著下降的趋势(通过信度为0.05的统计检验),而东南方沿海地区热带气旋影响明显增加,厦门、福州、温州、杭州和上海夏季(6—10月)受到影响的程度显著上升(福州、温州和杭州通过信度为0.05的统计,上海和厦门通过信度为0.1的统计检验)。进一步分析表明,热带气旋活动的这些变化与台风盛行路径和强度的变化有密切关系。  相似文献   

地球爆抛月球的地质痕迹     

冯宜全 《地球科学与环境学报》1994,(1)

根据６０年代的月质资料和海洋地质资料，全面总结地月关系和地质史，可以发现地球爆抛月球的地质痕迹和月质痕迹．１９７８年版世界地形图清楚地表明，全部深海盆、海沟、洋隆裂谷及陆地山脉裂谷、江河渠道等沉陷构造均呈线性闭合态，从而全球洋隆（指全部洋底隆起构造）和陆地统呈完全吻合性裂迹，全球地壳统呈向太平洋中心汇聚漂移和拉裂形变运动的营力痕迹，北－东－南太平洋海盆纵贯南北，其边缘不相吻合，显呈地球抛月质点──月坑抿合后的地质痕迹．而月壳则显呈月坑地壳包合月体的吻合性裂迹．这种全息性痕迹，是地球抛月海陆起源及地亮相对固定演化历史的核心论据。  相似文献   

Mesozoic thermal history of the Prebetic continental margin (southern Spain): Constraints from apatite fission-track analysis     

L. Barbero  A.C. Lpez-Garrido 《Tectonophysics》2006,422(1-4):115-128

Apatite fission-track analysis was applied to Triassic and Cretaceous sediments from the South-Iberian Continental Margin to unravel its thermal history. Apatite fission-track age populations from Triassic samples indicate partial annealing and point to a maximum temperature of around 100–110 °C during their post-depositional evolution. In certain apatites from Cretaceous samples, two different fission-track age populations of 93–99 and around 180 Ma can be distinguished. Track lengths associated with these two populations enabled thermal modelling based on experimental annealing and mathematical algorithms. These thermal models indicate that the post-depositional thermal evolution attained temperatures ≤ 70 °C, which is consistent with available vitrinite-reflectance data. Thermal modelling for the Cretaceous samples makes it possible to decipher a succession of cooling and heating periods, consisting of (a) a late Carboniferous–Permian cooling followed by (b) a progressive heating episode that ended approximately 120 Ma at a maximum T of around 110 °C. The first cooling episode resulted from a combination of factors such as: the relaxation of the thermal anomaly related to the termination of the Hercynian cycle; the progressive exhumation of the Hercynian basement and the thermal subsidence related to the rifting of the Bay of Biscay, reactivated during the Late Permian. Jurassic thermal evolution deduced from the inherited thermal signal in the Cretaceous sediments is characterized by progressive heating that ended around 120 Ma. This heating episode is related to thermal subsidence during Jurassic rifting, in agreement with the presence of abundant mantle-derived tholeiitic magmas interbedded in the Jurassic rocks. The end of the Jurassic rifting is well marked by a cooling episode apparently starting during Neocomiam times and ending at surface conditions by Albian times.  相似文献   

磷灰石裂变径迹技术与地学应用综述   总被引：3，自引：0，他引：3  

常远  刘锐  杨嘉 《上海国土资源》2004,(1):47-53

天然裂变径迹的形成和演化是一个连续不可逆的过程，经历了漫长地质演化的矿物的所有裂变径迹综合起来就可以看作一个热时钟体系。它不仅反映了矿物冷却到封闭温度(退火温度)的时间，还记录了矿物所经历的低于封闭温度的整个热历史的信息。由此可以建立起用于恢复矿物热史信息的各种模型(包括时间——温度模型)。这些模型的建立对沉积盆地沉降／埋藏历史、造山带浅部壳层冷却／剥露历史的研究以及低温热历史重建等地学方面的应用意义重大。  相似文献   

贵州剑河寒武纪凯里组遗迹群落中的节肢动物遗迹          下载免费PDF全文

王约 《地质论评》2007,53(4):I0007-I0010

贵州剑河凯里组中产有丰富的遗迹化石,本文描述了其中的节肢动物遗迹9个属23个种（其中1个新属,9个新种）和3种类型的趾迹。发现并讨论了节肢动物（三叶虫）的捕食迹和求偶迹及其形成过程;研究了节肢动物生活行为所产生行迹之间的变化,认为节肢动物各行迹之间的过渡类型的变化具有停息→爬行→行走→游泳和游泳→行走→爬行→停息两向性变化的特点,并认为在运动弯道上形成的过渡行迹可能与造迹生物在转弯处的运动惯性或与水动力造成造迹生物身体的倾斜有关。含丰富节肢动物遗迹的凯里生物群的沉积环境为正常浪基面和风暴浪基面之间的浅海软质基底低能环境。  相似文献   

西北太平洋热带气旋移动路径的年际变化及其机理研究   总被引：19，自引：3，他引：19  

黄荣辉  陈光华 《气象学报》2007,65(5):683-694

利用JTWC的热带气旋资料、NCEP/NCAR再分析的风场资料以及Scripps海洋研究所的海温资料分析了西北太平洋热带气旋(TC)移动路径的年际变化及其机理。结果表明,西北太平洋TC移动路径有明显的年际变化并与西太平洋暖池热状态有很密切的关系。当西太平洋暖池处于暖状态,西北太平洋上空TC移动路径偏西,影响中国的台风个数偏多;相反,当西太平洋暖池处于冷状态,西北太平洋的TC移动路径偏东,影响日本的台风个数偏多,而影响中国的台风个数可能偏少。本研究以西太平洋暖池处于冷状态的2004年与西太平洋暖池处于暖状态的2006年的西北太平洋TC移动路径的差别进一步论证了这一分析结果并从动力理论方面分析了在西太平洋暖池不同热状态下,季风槽对赤道西传天气尺度的Rossby重力混合波转变成热带低压型波动(TD型波动)的影响,以此揭示西太平洋暖池的热状态对西北太平洋TC生成位置与移动路径年际变化的影响机理。分析结果表明,当西北太平洋暖池处于暖状态时,季风槽偏西,使得热带太平洋上空对流层低层Rossby重力混合波转变成TD型波动的位置也偏西,从而造成TC生成平均位置偏西,并易于出现西行路径;相反,当西太平洋暖池处于冷状态时,季风槽偏东,这造成了对流层低层Rossby重力混合波转变成TD型波动的区域,以及TC生成的平均位置都偏东,从而导致TC移动路径以东北转向为主。  相似文献   

Radon emanometry in soil gases and activity in ashes from El Chichon Volcano     

S. De la Cruz-Reyna  M. Mena  N. Segovia  J. F. Chalot  J. L. Seidel  M. Monnin 《Pure and Applied Geophysics》1985,123(3):407-421

Radon (²²²Em) emanation measurements in soil gases are reported in connection with the 1982 eruptions of El Chichón Volcano.²²²Em detection is performed with LR-115 cellulose nitrate track detectors. Results show a general decreasing pattern of²²²Em concentration in soil with time after the eruptions. Activity measurements of radon daughters in ashes show that a large amount of²²²Em and²²⁰Em was released from magma degassing during the eruptions, and that only a fraction of the degassed magma was erupted. An important fluid interaction between the magma chamber and the surrounding sedimentary rock is also suggested.  相似文献   

中国近海TOPEX／POSEIDON卫星测高数据处理的初步结果   总被引：8，自引：2，他引：8  

邓晓丽  晁定波  陈俊勇 《测绘学报》1996,25(3):226-232

本文分析处理了ＴＯＰＥＸ／ＰＯＳＥＩＤＯＮ卫星１～８２周期的测高数据。重新计算了逆气压改正数；利用共线法计算的ＴＯＰＥＸ和ＰＯＳＥＩＤＯＮ之间相对偏差估值为１９．９±１ｃｍ；将编辑后的海面高与Ｂａｓｉｃ和ＲａＰＰ计算的平均海面高进行比较，发现二者之间存在明显的系统偏差。  相似文献   

Thermochronology of allochthonous terranes in Ecuador: Unravelling the accretionary and post-accretionary history of the Northern Andes     

R.A. Spikings  W. Winkler  R.A. Hughes  R. Handler 《Tectonophysics》2005,399(1-4):195

The western cordilleras of the Northern Andes (north of 5°S) are constructed from allochthonous terranes floored by oceanic crust. We present ⁴⁰Ar/³⁹Ar and fission-track data from the Cordillera Occidental and Amotape Complex of Ecuador that probably constrain the time of terrane collision and post-accretionary tectonism in the western Andes. The data record cooling rates of 80–2 °C/my from temperatures of 540 °C, during 85 to 60 Ma, in a highly tectonised mélange (Pujilí unit) at the continent–ocean suture and in the northern Amotape Complex. The rates were highest during 85–80 Ma and decelerated towards 60 Ma. Cooling was a consequence of exhumation of the continental margin, which probably occurred in response to the accretion of the presently juxtaposing Pallatanga Terrane. The northern Amotape Complex and the Pujilí unit may have formed part of a single, regional scale, tectonic mélange that started to develop at ~85 Ma, part of which currently comprises the basement of the Interandean Depression. Cooling and rotation in the allochthonous, continental, Amotape Complex and along parts of the continent–ocean suture during 43–29 Ma, record the second accretionary phase, during which the Macuchi Island Arc system collided with the Pallatanga Terrane. Distinct periods of regional scale cooling in the Cordillera Occidental at 13 and 9 Ma were synchronous with exhumation in the Cordillera Real and were probably driven by the collision of the Carnegie Ridge with the Ecuador Trench. Finally, late Miocene–Pliocene reactivation of the Chimbo–Toachi Shear Zone was coincident with the formation of the oldest basins in the Interandean Depression and probably formed part of a transcurrent or thrust system that was responsible for the inception and subsequent growth of the valley since 6 Ma.  相似文献