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111.
Patricia A. Lockridge 《Natural Hazards》1990,3(4):403-412
While earthquakes generate about 90% of all tsunamis, volcanic activity, landslides, explosions, and other nonseismic phenomena can also result in tsunamis. There have been 53 000 reported deaths as a result of tsunamis generated by landslides and volcanoes. No death tolls are available for many events, but reports indicate that villages, islands, and even entire civilizations have disappeared. Some of the highest tsunami wave heights ever observed were produced by landslides. In the National Geophysical Data Center world-wide tsunami database, there are nearly 200 tsunami events in which nonseismic phenomena played a major role. In this paper, we briefly discuss a variety of nonseismic phenomena that can result in tsunamis. We discuss the magnitude of the disasters that have resulted from such events, and we discuss the potential for reducing such disasters by education and warning systems. 相似文献
112.
局地强风暴云团与中尺度锋面波动 总被引:6,自引:0,他引:6
本文分析了1982—1988年2—5月份的41例与中尺度锋面波动相关联的局地强风暴云团的活动和演变特征,给出了其强盛期天气系统配置模式及其在天气尺度云系演变中的表现型式,最后对其移动做了一般性讨论。 相似文献
113.
The paper of Reid and Whitaker (1976) on the effects of a vegetation canopy on flow of water is re-examined. Their assumptions on the equality of various drag coefficients are replaced by more realistic calculations. A new method for calculating wind stress on water is presented for the case when the vegetation extends above the water surface.For the case of vanishingly small water depth, it is shown that the horizontal stress is approximately constant in the vertical. This results in a diagnostic relationship for the water current as a function of the wind stress and bottom roughness.A new expression for the vertically averaged frictional force per unit mass is derived on the assumption that the friction velocity varies linearly with height. The vertical rate of change of friction velocity depends on the mean water current, the wind stress, the bottom roughness, and the water depth. This work has a possible application in the mitigation of storm surges. 相似文献
114.
冬季西北太平洋海表温度异常对太平洋风暴轴影响的数值试验 总被引:6,自引:5,他引:6
采用T21L5大气环流模式,详细探讨了冬季西北太平洋海表温度异常对太平洋风暴轴的影响。结果表明:冬季西北太平洋暖海表温度异常能显著增强异常区北侧及下游地区的斜压性,天气尺度扰动方差、扰动动能以及涡动热量通量等也在此风暴轴入口区得到增强,由此揭示出外热源强迫对太平洋风暴轴的维持和发展起重要作用。 相似文献
115.
116.
台风影响期间珠江三角洲局地强风暴和大暴雨发生的环境条件 总被引:4,自引:0,他引:4
采用1976-1983年6-8月珠江三角洲地区受台风影响期间区内各站逐日的强风暴和降水资料以及广泛站的探空资料,用相关对比度分析方法,对台风环流中的珠江三角洲局地强风暴和大暴雨发生的环境条件进行统计诊断,得出台风影响珠江三角洲时这两种强天气发生的有利的环境条件,并发现二者在气压、风速、层结稳定度和中下层位势不稳定等方面显著不同。 相似文献
117.
118.
G. A. Mansilla 《Studia Geophysica et Geodaetica》2007,51(4):563-574
An investigation of the response of the mid-high, mid and low latitude critical frequency foF2 to the geomagnetic storm of
15 July 2000 is made. Ground-based hourly foF2 values (proportional to square root of peak electron density of F2-layer) from
four chains of ionospheric stations located in the geographic longitude ranges 10°W–35°E, 60°E–120°E, 130°E–170°E, 250°E–295°E
are used. Relative deviations of foF2 are considered. The main ionospheric effects for the considered storm are: long-duration
negative disturbances at mid-high latitudes in summer hemisphere in sectors where the storm onset occurred in the afternoon/night-time
hours; short-duration positive disturbances in the summer hemisphere at mid-high latitudes in the pre-sunset hours during
the end of main phase-first stage of the recovery; small and irregular negative disturbances in the low latitude winter hemisphere
which predominate during the main phase and first part of the recovery, and positive disturbances in both hemispheres at mid-high
and mid latitudes prior to the storm onset irrespective of the local time. In addition, the validity of some physical mechanisms
proposed to explain the F2 region behaviour during disturbed conditions is considered.
gus-mansilla@hotmail.com 相似文献
119.
The structure of the mid- and high-latitude ionosphere during the November 2004 storm event obtained from GPS observations 总被引:1,自引:1,他引:1
Andrzej Krankowski Irk I. Shagimuratov Lubomir W. Baran Galina Yakimova 《Acta Geophysica》2007,55(4):490-508
GPS data from the International GNSS Service (IGS) network were used to study the development of the severe geomagnetic storm
of November 7–12, 2004, in the total electron content (TEC) on a global scale. The TEC maps were produced for analyzing the
storm. For producing the maps over European and North American sectors, GPS measurements from more than 100 stations were
used. The dense network of GPS stations provided TEC measurements with a high temporal and spatial resolution. To present
the temporal and spatial variation of TEC during the storm, differential TEC maps relative to a quiet day (November 6, 2004)
were created.
The features of geomagnetic storm attributed to the complex development of ionospheric storm depend on latitude, longitude
and local time. The positive, as well as negative effects were detected in TEC variations as a consequence of the evolution
of the geomagnetic storm. The maximal effect was registered in the subauroral/auroral ionosphere during substorm activity
in the evening and night period. The latitudinal profiles obtained from TEC maps for Europe gave rise to the storm-time dynamic
of the ionospheric trough, which was detected on November 7 and 9 at latitudes below 50°N. In the report, features of the
response of TEC to the storm for European and North American sectors are analyzed. 相似文献
120.
海洋风暴形成的一种动力学机制 总被引:3,自引:0,他引:3
文中从观测统计学、瞬变涡动能量学和 MM5中尺度数值模拟角度 ,研究了海洋风暴 (爆发性气旋 )形成的气候特征及其可能的动力学机制 ,揭示了一幅爆发性发展的物理图像。结果表明 ,在冷季大气特别是日本以东洋面上大气特有的热力气候背景下 ,通过同海洋风暴过程相联系的涡动热通量 vθ的向极地输送 (- vθ· θm>0 ) ,将季节尺度的时间平均有效位能向瞬变涡旋时间尺度的涡动有效位能转换 ,是海洋风暴形成的主要动力机制。在该过程中转换来的具有最大贡献的涡动有效位能 ,连同具有次大贡献的积云加热制造的涡动有效位能(q3 )一起 ,通过暖异常区 (α >0 )暖湿空气上升运动 (-ω >0 )的斜压转换 (-ωα) ,促使涡动动能增长。同时 ,补充的涡动有效位能又加强了暖异常区的暖湿空气上升运动 ,进而产生积云对流活动及其潜热释放的正反馈过程 ,最终导致涡动动能急剧增长和海洋风暴的形成。海-气潜热输送的作用是在风暴形成初期提供后来积云尺度对流活动及潜热释放的水汽潜力。研究还表明 ,海洋风暴主要发生在冷季月份 1 3 0°E以东的中高纬洋面上 ,这种对特定季节和特定海域的依赖性是大气和海洋气候背景的动力 /热力共同作用的结果 相似文献