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171.
一种运用云顶亮温确定热带气旋海面大风区的方法 总被引:7,自引:1,他引:7
运用1996—1997年间16个热带气旋的GMS红外云图云顶亮温(TBB)和国内外热带气旋大风报告,以及部分常规和船舶测风报告,通过统计分析,概括出可确定热带气旋7级和10级以上大风区的几种TBB场概略模型图,试图形成一种可供业务参考使用的大风区确定方法。 相似文献
172.
两类ENSO事件前期的热带太平洋海温距平场 总被引:7,自引:2,他引:7
分析了1956年以来两类ENSO事件热带太平洋海温距平场的特征。结果指出,东部型ElNino事件前期为LaNina事件年,热带中东太平洋为强的海温负距平,东部型LaNina事件前期为ElNino事件年,热带中不太平洋为强的海温正距平,中部型ElNino事件前期热带中西太平洋多为明显的海温正距平,中部型LaNina事件前期热带东太平洋多为明显的海渐负距平。两类ENSO事件前期海温距平场特殊基本相反。 相似文献
173.
Antoine Mocquet 《Journal of Seismology》2007,11(4):381-403
The October 21, 1766 earthquake is the most widely felt event in the seismic history of Trinidad and Venezuela. Previous works
diverged on the interpretation of the historical data available for this event. They associated the earthquake either with
the Lesser Antilles subduction zone, with strike-slip motion along El Pilar fault, or with intraplate deformation at the edge
of Guyana shield. Isoseismal areas are proposed after a new search and analysis of primary and secondary sources of historical
information. Two of the largest earthquakes of the twentieth century which occurred in the region, the 1968 (M
S 6.4, h = 103 km), and the 1997 (M
W 6.9, h = 25 km) events, for which both intensity data and instrumentally determined source parameters are available, are used to
calibrate the isoseismal areas and to interpret them in terms of source depth and magnitude. It is concluded that the large
extent of intensity values higher than V is diagnostic of the depth (85 ± 20 km) of the 1766 source, and of local amplifications
of ground motion due to soft soil conditions and to strong contrasts of impedance at the edge of Guyana shield. It is proposed
that the event occurred either in slab, or close to the bottom lithospheric interface between the Caribbean and South American
plates (∼11°N; ∼62.5°W). The value of the magnitude is estimated at 6.5 < M
S < 7.5 depending on the source depth and on the decay of ground motion as a function of distance. Deep and intermediate depth
earthquakes can induce important casualties in Trinidad, Venezuela, and Guyana, possibly more damaging than those induced
by shallower earthquakes along the strike of El Pilar Fault. 相似文献
174.
本文基于地震烈度数据点,用椭圆参数方程对烈度点空间分布进行最小二乘拟合,得到各烈度区椭圆烈度估计线,然后对烈度估计线进行统计回归,得到一组适用于青、甘、川、滇4省中强地震的椭圆烈度分布模型I=f(M,R).基于所建烈度分布模型,联立考虑中心点和方向性的椭圆数学方程,代入全部烈度数据点估算地震震级和宏观震中.本文的试算震例表明了此方法的可行性,并进行了不确定性分析.利用该方法对明清时期4次烈度点较少的中强历史地震参数进行了估算,所得结果表明了此方法对历史地震有效. 相似文献
175.
Assessment of the ecological quality status of soft-bottoms in Reunion Island (tropical Southwest Indian Ocean) using AZTI marine biotic indices 总被引:2,自引:1,他引:1
Bigot L Grémare A Amouroux JM Frouin P Maire O Gaertner JC 《Marine pollution bulletin》2008,56(4):704-722
The ability of the two synthetic marine biotic indices, AMBI and M-AMBI, to account for changes in the ecological quality of coastal soft bottoms of Reunion Island according to disturbances was assessed from macrobenthic samples collected in five sectors between 1994 and 2004. Samples were collected under non-perturbed conditions and at two sites subjected to heavy organic enrichment. Both indices are based on a classification of macrofauna into ecological groups (EG), and their transfer to tropical waters required some adaptations. These indices proved efficient in detecting a degradation of habitat quality. Their use resulted in the classification of all sites sampled between 1996 and 1998 as "good" or "high". M-AMBI nevertheless tended to result in the attribution of a slightly worse ecological quality status than AMBI. Together with an update of the EG species list for the Indian Ocean area, our results support the extension of both indices for the assessment of tropical soft bottoms. 相似文献
176.
177.
Brittany D. Brand Amanda B. Clarke 《Journal of Volcanology and Geothermal Research》2009,180(2-4):203
The Table Rock Complex (TRC; Pliocene–Pleistocene), first documented and described by Heiken [Heiken, G.H., 1971. Tuff rings; examples from the Fort Rock-Christmas Lake valley basin, south-central Oregon. J. Geophy. Res. 76, 5615-5626.], is a large and well-exposed mafic phreatomagmatic complex in the Fort Rock–Christmas Lake Valley Basin, south-central Oregon. It spans an area of approximately 40 km2, and consists of a large tuff cone in the south (TRC1), and a large tuff ring in the northeast (TRC2). At least seven additional, smaller explosion craters were formed along the flanks of the complex in the time between the two main eruptions. The first period of activity, TRC1, initiated with a Surtseyan-style eruption through a 60–70 m deep lake. The TRC1 deposits are dominated by multiple, 1-2 m thick, fining upward sequences of massive to diffusely-stratified lapilli tuff with intermittent zones of reverse grading, followed by a finely-laminated cap of fine-grained sediment. The massive deposits are interpreted as the result of eruption-fed, subaqueous turbidity current deposits; whereas, the finely laminated cap likely resulted from fallout of suspended fine-grained material through a water column. Other common features are erosive channel scour-and-fill deposits, massive tuff breccias, and abundant soft sediment deformation due to rapid sediment loading. Subaerial TRC1 deposits are exposed only proximal to the edifice, and consist of cross-stratified base-surge deposits. The eruption built a large tuff cone above the lake surface ending with an effusive stage, which produced a lava lake in the crater (365 m above the lake floor). A significant repose period occurred between the TRC1 and TRC2 eruptions, evidenced by up to 50 cm of diatomitic lake sediments at the contact between the two tuff sequences. The TRC2 eruption was the last and most energetic in the complex. General edifice morphology and a high percentage of accidental material suggest eruption through saturated TRC1 deposits and/or playa lake sediments. TRC2 deposits are dominated by three-dimensional dune features with wavelengths 200–500 m perpendicular to the flow, and 20–200 m parallel to the direction of flow depending on distance from source. Large U-shaped channels (10–32 m deep), run-up features over obstacles tens of meters high, and a large (13 m) chute-and-pool feature are also identified. The TRC2 deposits are interpreted as the products of multiple, erosive, highly-inflated pyroclastic surges resulting from collapse of an unusually high eruption column relative to previously documented mafic phreatomagmatic eruptions. 相似文献
178.
海南尖峰岭热带山地雨林作为典型的热带雨林生态系统之一,其长期的气候动态变化研究对全球变化研究有着重要的作用。采用1980—2005年海南尖峰岭森林生态系统国家野外科学观测研究站天池气象站地面常规气象观测资料,利用累积距平法和Mann-Kendall检验法分析了尖峰岭热带山地雨林区气候突变和气候异常,结果表明:该区26 a来,年平均气温、年平均地温、年平均最高最低气温、年积温和平均水汽压在1990年前后经历一次由低到高的突变,年平均风速在1993年经历由大到小的突变。在高强度ENSO事件发生的1998年,气温、地温均出现异常偏高,这些都表明该林区的森林气候变化正是对全球气候异常的明显响应过程。 相似文献
179.
介绍了在MM5模式基础上建立起来的辽宁省热带气旋模式预报业务系统及2005年的预报情况。系统以T213L31产品为背景场和侧边界,初始场中同化了常规探空报、地面报及一些卫星反演资料,模式的初值中还嵌入人造热带气旋进行模式运算。系统每日自动运行2次;模式输出结果经后处理后,编写到通用绘图软件GrADs中,以图形显示,并在沈阳区域气象中心局域网的中尺度数值预报网页上显示。2005年汛期热带气旋预报表明,系统对热带气旋的路径和暴雨的预报效果较好。 相似文献
180.
Intensity-based seismic risk assessment 总被引:1,自引:0,他引:1