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301.
Idealized Numerical Simulations of Tropical Cyclone Formation Associated with Monsoon Gyres简 总被引:1,自引:0,他引:1
Monsoon gyres have been identified as one of the important large-scale circulation patterns associated with tropical cyclone (TC) formation in the western North Pacific.A recent observational analysis indicated that most TCs form near the center of monsoon gyres or at the northeast end of the enhanced low-level southwesterly flows on the southeast-east periphery of monsoon gyres.In the present reported study,idealized numerical experiments were conducted to examine the tropical cyclogenesis associated with Rossby wave energy dispersion with an initial idealized monsoon gyre.The numerical simulations showed that the development of the low-level enhanced southwesterly flows on the southeasteast periphery of monsoon gyres can be induced by Rossby wave energy dispersion.Mesoscale convective systems emerged from the northeast end of the enhanced southwesterly flows with mid-level maximum relative vorticity.The simulated TC formed in the northeast of the monsoon gyre and moved westward towards the center of the monsoon gyre.The numerical experiment with a relatively smaller sized initial monsoon gyre showed the TC forming near the center of the initial monsoon gyre.The results of the present study suggest that Rossby wave energy dispersion can play an important role in TC formation in the presence of monsoon gyres. 相似文献
302.
13个水稻新不育系育性指标生态特性研究 总被引:1,自引:0,他引:1
以1997~1998年度参试的13个新不育系为材料,依据在三亚市、武汉市和贵阳市三个地理生态区,进行分期播种试验所获得的套袋自交结实率和温度、日照长度资料,采用光温因子分极和育性量化模型等两种分析方法进行育性指标的生态特性研究,并初步分析了它们的生产实用价值。 相似文献
303.
济阳盆地中生代构造特征与油气 总被引:56,自引:6,他引:56
济阳盆地中生代构造主要包括:印支期NW向压性构造(褶皱及逆断层)、消亡的NW向负反转半地垒及半地堑、燕山期ENE向压性构造(褶皱或逆断层)、SN向地垒。印支期NW向压性构造是华北板块同扬子板块的聚敛运动的产物,而NW向负反转地垒和地堑、ENE向压性构造及SN向地垒导源于郯庐断裂的左旋剪切作用,新生代郯庐断裂右旋剪切运动导致上述构造消亡并成为隐伏构造。中生代隐伏构造为济阳盆地深层勘探提供了潜山圈闭( 相似文献
304.
2009年深秋河北省特大暴雪天气成因分析 总被引:12,自引:5,他引:12
利用多种资料对2009年11月10—11日河北省特大暴雪天气过程进行了分析。结果表明:冷锋系统长时间影响河北,并产生正、逆双向次级环流,其强上升运动与中层强辐合及正涡度柱耦合,为暴雪提供了很好的动力条件;由于锋面附近强温度梯度及风的垂直切变作用,在暴雪区形成条件性对称不稳定和对流不稳定;另外西南暖湿气流为暴雪提供了充沛的水汽条件,强上升运动可将水汽输送到高空冷区凝华、冻结为雪及冰晶;向东开口的喇叭口地形使得干冷空气在低层堆积,增强了回流降雪的低层冷垫作用;在低层由于地形作用产生的弱上升运动与锋面次级环流上升运动叠加,有利于强对流天气发展和增强。 相似文献
305.
Ian Shennan David B. Scott Mairead Rutherford Yongqiang Zong 《Quaternary International》1999,60(1):275
Diatom, pollen, foraminifera and thecamoebian assemblages from an outcrop of peat and silt at Girdwood Flats, in the upper Turnagain Arm of the Cook Inlet, Alaska, record four phases of relative land and sea-level changes. The first phase is the development of freshwater swamp above high marsh sediments during relative land uplift, caused by strain accumulation along the locked portion of the Alaska-Aleutian subduction zone. In second phase, the top 2 cm of the peat, all microfossil groups record pre-seismic relative sea-level rise (relative land subsidence). The third phase is rapid land subsidence, 1.7 m, during the earthquake of March 1964 that initiated intertidal silt accumulation above the peat. The final phase is the colonisation of mudflat by salt marsh communities during post-seismic land uplift. The microfossil data compare favourably with sequences from Washington, Oregon and British Columbia that record late Holocene submergence events caused by earthquakes. The comparable changes in microfossil assemblages record the different phases of relative land and sea-level changes and the magnitude of land subsidence caused by each earthquake (expressed relative to the tidal range at the site). These results raise the question whether preseismic sea-level rise represents any kind of warning of large earthquakes. 相似文献
306.
20个激变变星或相关天体的分光证认 总被引:1,自引:0,他引:1
在20个研究得很少的激变变星或者曾经被分类为激变变星的相关天体的光谱中,13个被证实为属于激变变星(65%),另外7个似乎应该被排除(表1第8列),不像其他研究者那样,仅给出非激变变星或热天体,还以更强的证据和更多的光谱特征征认出1个DA型白矮星,4个双星系统及其子星的光谱型。新的光谱资料不支持FY Per的Herbig Ae/Be分类,它是一个激变变星。对于PG1712+493,不仅给出星和云的 相似文献
307.
308.
根据声波反射法探测顶煤厚度中存在的问题,提出了将小波多尺度分析应用到实际煤厚探测信号分析中的信号处理方法。结果表明:小波多尺度分析大大改善了煤层顶板弱反射波的识别能力,提高了煤厚探测的精度。 相似文献
309.
Korean Sewol is successfully lifted up with the strand jack system based on twin barges. During the salvage operation, two barges and Sewol encounter offshore environmental conditions of wave, current and wind. It is inevitable that the relative motions among the three bodies are coupled with the sling tensions, which may cause big dynamic loads for the lifting system. During the project engineering phase and the site operation, it is necessary to build up a simulation model that can precisely generate the coupled responses in order to define a suitable weather window and monitor risks for the salvage operation. A special method for calculating multibody coupled responses is introduced into Sewol salvage project. Each body’s hydrodynamic force and moment in multibody configuration is calculated in the way that one body is treated as freely moving in space, while other bodies are set as fixed globally. The hydrodynamic force and moment are then applied into a numerical simulation model with some calibration coefficients being inserted. These coefficients are calibrated with the model test results. The simulation model built up this way can predict coupled responses with the similar accuracy as the model test and full scale measurement, and particularly generate multibody shielding effects. Site measured responses and the responses only resulted from from the simulation keep project management simultaneously to judge risks of each salvage stage, which are important for success of Sewol salvage. 相似文献
310.
气象服务需求是气象经济学中亟待深入研究的问题。从经济学的需求意义上,立足于气象服务实践,提出气象服务需求主体与需求客体,进而把需求主体划分为政府和企业,把需求客体划分为公共产品和服务商品。并在此基础上,重点剖析制约公共气象服务产品的需求因素和制约气象商品的需求因素 相似文献