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51.
西南低涡是对流层下层的中尺度扰动。本文在零级近似条件下,采用p坐标系的基本方程组,在边界层内设计两层模式。通过一定的简化方程组后,得到:当Z≤1/2[kL~2/(μ~2Knu~*)] 时,摩擦效应具有二重性,一方面使扰动减弱;另一方面使扰动增强,而前者的影响略大于后者,最终使扰动消失。频率随高度Z的降低而增加。当Z>1/2[kL~2/(μ~2Knμ~*)]时,摩擦作用甚微,几乎可以忽略不计。频率虽然有两个值,但随高度Z的增加,他们趋于一个常值。 相似文献
52.
Xie Rui-xiang Wang Min Shi Shuo-biao Xu Chun Li Wei-hua Yan Yi-hua 《Chinese Astronomy and Astrophysics》2003,27(4):426-434
Using the decimetric (700–1500 MHz) radio spectrometer and the synchronous observational system with high temporal resolution at four frequencies (1420, 2130, 2840 and 4260 MHz) of Yunnan Observatory, two rare events were observed on 2001 June 24 and 1990 July 30. The former was a small radio burst exhibiting pulsations with short periods (about 29, 40 and 100 ms) in the impulsive phase. The latter was a large radio burst, which at 2840 MHz produced radio pulsations with period of about 30 ms. This paper focuses on pulsations with very short periods in the range of 29–40 ms. The mechanism of generation of such pulsations may be modulation of radio radiation by the periodic trains of whistler packets originating in unstable regions of the corona. Alternatively, these pulsations can be attributed to wave-wave non-linear interactions of electrostatic upper hybrid waves driven by beams of precipitating electrons in flaring loops. 相似文献
53.
54.
Pollen-based reconstructions of Holocene vegetation and climatic change of Tibetan Plateau 总被引:2,自引:0,他引:2
A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that the vegetation shifted from subalpine/alpine conifer forest to subalpine/alpine evergreen sclerophyllous forest in the southeastern part of the plateau; from alpine steppe to alpine desert in the central, western and northern part; and from alpine meadow to alpine steppe in the eastern and southern plateau regions during the Holocene. These records show that increases in precipitation began about 9 ka from the southeast, and a wide ranging level of increased humidity developed over the entire of the plateau around 8-7 ka, followed by aridity from 6 ka and a continuous drying over the plateau after 4-3 ka. The changes in Holocene climates of the plateau can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Indian Monsoon which expanded northwards 相似文献
55.
恢复地层剥蚀厚度是研究盆地演化史和进行油气资源评价的重要基础工作。奈曼凹陷作为开鲁盆地中一个重要的沉积凹陷,整体勘探程度不高。本文运用地震地层厚度趋势法辅之以构造沉积综合法恢复了奈曼凹陷北部地区下白垩统九佛堂组上段和下段的古地层厚度及地层剥蚀量分布范围;同时结合奈曼地区构造演化特征和沉积相特征确定了奈曼凹陷北部地区的沉降中心位于奈10井区域,明确了九佛堂组时期原始沉积相展布特征。在物源供给方面,北部物源受搬运距离远及剥蚀难以存留的影响未能沉积,主要来自于西部陡坡带发育的扇三角洲相沉积及东部缓坡带发育的辫状河三角洲相沉积。此外,研究还发现奈曼凹陷北部地区下白垩统古地层厚度地质模型特征为北东向受抬升剥蚀最严重,剥蚀范围广,剥蚀厚度大。此次研究对于揭示该区域的构造演化历史及油气成藏过程有一定的参考价值。同时,本次研究方法的应用对于类似沉积盆地的剥蚀量恢复研究也具有借鉴意义。
相似文献56.
Cheng San Zhang Zhi-Yong Zhou Feng Li Man Chen Hui Shi Fu-Sheng Huang Lin-Pin Li Yong 《应用地球物理》2021,(3):375-385
A three-dimensional (3D) step-by-step inversion strategy for audio magnetotellurics(AMT) is investigated in this study.The objective function is minimized by it... 相似文献
57.
CHEN Meixiang) ZUO Juncheng) LI Peiliang) DU Ling) and LI Lei)) Oceanography Department Ocean University of China Qingdao P. R. China ) Key Laboratory of Coastal Disaster Defence Ministry of Education Hohai University Nanjing P. R. China 《中国海洋大学学报(英文版)》2007,6(2):117-124
Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area. 相似文献
58.
A preliminary application GIS in glaciological research along the traverse route from Zhongshan Station to Dome A, Antarctica 总被引:1,自引:0,他引:1
1 IntroductionGeographicalinformationsystem (GIS)isanefficientwayandimportanttechniquetomanage,displayandanalyzeAntarcticspatialdata.GIScanbeusedtomakeandre newmapproductsquickly ,evaluateenvironment,supportlogisticmanagementandfieldoperation,providechancetoextractnewknowledge,andtopromoteinformationex changeamongnationsunderthedemandoftheMadridProtocol(AADC 2 0 0 1 ;MAGIC1 998;1 999) .WorkingGroupofGeodesyandGeographicInformation (WG GGI)ofScientificCommitteeonAntarcticResearch (… 相似文献
59.
黄河断流后三角洲(水上平原)的滑塌构造研究 总被引:8,自引:3,他引:8
黄河断流后三角洲 (水上平原 )上的滑塌构造非常发育,在分流河道中几乎随处可见,它们主要发育在边滩、心滩外缘、周缘或内部的水道中,还可以发育在河床上。滑塌作用形成了三种产物:滑塌壁或滑塌缝 滑塌体和滑塌碎块及滑塌变形基底。滑塌壁或滑塌缝按力学机制可能分为两种类型 一种是张性 另一种是剪性。滑塌壁或滑塌缝的规模不一,大者长度可超过十余米,甚至二十余米,小者长度只有 3~ 5cm 滑塌体规模差别也较大,大者高度可超过 1m,长度可达 3~ 4m 小者高度和长度仅数cm。通过观察发现,滑塌构造的产生与波浪的掏洗和流水冲蚀有关,与地震和斜坡滑动关系不大。黄河断流后在某些低洼河道积水成“湖”,“湖”水在风的作用下形成波浪。波浪不断拍击导致边滩、心滩产生滑塌,形成一系列相应的滑塌构造 再者,黄河断流后边滩、心滩广泛暴露,黄河三角洲地区降雨后使边滩、心滩和河床上汇集成径流,径流的冲蚀也可以形成一系列滑塌构造。有的滑塌构造被风成砂埋藏后很容易被何存下来,而充填滑塌缝之间的风成砂经成岩作用之后则有可能转变成砂岩岩墙。 相似文献
60.
Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China. However, the development of mega-urban agglomerations has triggered the interactive coercion between resources and the eco-environment. The interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations represent frontier and high-priority research topics in the field of Earth system science over the next decade. In this paper, we carried out systematic theoretical analysis of the interactive coupling mechanisms and coercing effects between urbanization and the eco-environment in mega-urban agglomerations. In detail, we analyzed the nonlinear-coupled relationships and the coupling characteristics between natural and human elements in mega-urban agglomerations. We also investigated the interactive coercion intensities between internal and external elements, and the mechanisms and patterns of local couplings and telecouplings in mega-urban agglomeration systems, which are affected by key internal and external control elements. In addition, we proposed the interactive coupling theory on urbanization and the eco-environment in mega-urban agglomerations. Furthermore, we established a spatiotemporal dynamic coupling model with multi-element, multi-scale, multi-scenario, multi-module and multi-agent integrations, which can be used to develop an intelligent decision support system for sustainable development of mega-urban agglomerations. In general, our research may provide theoretical guidance and method support to solve problems related to mega-urban agglomerations and maintain their sustainable development. 相似文献