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Asymmetric rainband breaking in Typhoon Haitang (2005) before and after its landfall 总被引:1,自引:1,他引:0
Using the WRF (Weather Research Forecast) model, this work performed analysis and simulation on the rainband change during the landfall of Typhoon Haitang (2005) and found that breaking may occur over land and oceans leads to distinct asymmetric precipitation. The breaking is related to the topographic effect as well as interactions between the typhoon and midlatitude systems at upper levels. During the landfall, divergent flows at the 200-hPa level of the South-Asian high combined with divergent flows at the periphery of the typhoon to form a weak, inverted trough in the northwest part of the storm, with the mid- and low-level divergence fields on the west and northwest side of the typhoon center maintaining steadily. It intensifies the upper-level cyclonic flows, in association with positive vorticity rotating counterclockwise together with air currents that travel stepwise into a vorticity zone in the vicinity of the typhoon core, thereby forming a vorticity transfer belt in 22–25? N that extends to the eastern part of the storm. It is right here that the high-level vorticity band is subsiding so that rainfall is prevented from developing, resulting in the rainbelt breaking, which is the principal cause of asymmetric precipitation occurrence. Migrating into its outer region, the banded vorticity of Haitang at high levels causes further amplification of the cyclonic circulation in the western part and transfer of positive vorticity into the typhoon such that the rainband breaking is more distinct. 相似文献
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Characteristics of intensity change in tropical cyclones affecting the South China Sea from 1977 to 2007 总被引:1,自引:1,他引:0
The best track data of tropical cyclones (TCs) provided by Regional Specialized Meteorological Center (RSMC) Tokyo for the South China Sea (SCS) from 1977 to 2007 are employed to study the spatiotemporal variations (for a period of 12 hours) and the rapid (slow) intensification (RI/SI) of TCs with different intensity. The main results are as follows. (1) Over this period, the tropical storms (TSs) and severe tropical storms (STSs) mostly intensify or are steady while the typhoons (TYs) mostly weaken. The stronger a TC is initially, the more observation of its intensification and the less its variability will be; the more observation of its weakening is, the larger its variability will be. (2) The TC intensifies the fastest at 0000 UTC while weakening the fastest at 1200 UTC. (3) In the intensifying state, TSs, STSs, and TYs are mainly active in the northeastern, central-eastern, and central SCS respectively. The weakening cases mainly distribute over waters east off Hainan Island and Vietnam and west off the Philippines. Some cases of TSs and STSs weaken over the central SCS. (4) The RI cases form farther south in contrast to the SI cases. The RI cases are observed in regions where there are weaker vertical shear and easterly components at 200 hPa. The RI cases also have stronger mid-and lower-level warm-core structure and smaller radii of 15.4 m/s winds. The SI cases have slightly higher SST. 相似文献
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连日来,由市国土资源局开展的测绘地理信息行政执法检查正在全市进行。从2013年6月起,该局加强测绘地理信息行政执法,进一步加强测绘地理信息监管,推进《测绘法》的贯彻实施,维护测绘地理信息市场秩序。该局成立全市测绘地理信息行政执法检查领导小组,负责组织落实执法检查工作。 相似文献
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北大别穹隆是在早白垩世造山后伸展活动中形成的。其北界为北西西走向、倾向北北东、正左行平移的晓天-磨子潭韧性剪切带,南界为北西走向、倾向南东、右行“逆冲”的五河-水吼韧性剪切带。通过对这两条剪切带的构造观测、运动学分析、石英C轴组构测量、变形温度分析及变形模拟,表明剪切带原先为中地壳同一近水平的韧性拆离剪切带。该拆离剪切带在原始近水平状态时的活动为上盘向280°方位的伸展运动。随后在大规模岩浆活动与北大别穹隆的隆升中,这一剪切带被动地抬升与剥露,而出露于现今的穹隆边界上。变形模拟显示,北大别穹隆构造现今为近EW轴向的背形,其上隆幅度西强东弱。北大别穹隆的形成过程表明为典型的造山带变质核杂岩。 相似文献
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杭州地铁储气砂土的渗气性试验研究 总被引:3,自引:1,他引:2
浅层气地质灾害对工程的影响日益受到重视,认清储气土层的气渗透特性是采取积极有效工程措施防治灾害影响的基础。以杭州地铁所遇的储气砂为研究对象,利用自制的渗气性量测装置对其进行了系统的试验研究。结果表明:地铁工程所遇的浅层气储气砂层属渗透性极好储层,渗透率达2 960×10-3 ?m2;砂土中气渗透规律符合达西定律;饱和度较低时,含水率的增加对砂土的渗气性影响很小;随着饱和度的增加,气渗透性逐渐减弱,在饱和度大于80 %后,渗气系数急剧减小直至完全不透气;饱和度的变化相对于干密度对储气砂土的渗气性影响更为显著。 相似文献
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