登陆台风变性过程的物理机制分析   总被引：7，自引：5，他引：2  

张雪蓉  陈联寿  濮梅娟  徐海明  李英 《气象科学》2013,33(6):685-692

0509号台风“Matsa”和0712号台风“Wipha”,均在中国大陆发生变性成为温带气旋。但前者变性后再度加强,后者变性后减弱消亡。用日本JRA25再分析资料,对其变性过程对比分析。表明：“Matsa”和“Wipha”均是在登陆后北上与中高纬西风槽相互作用的过程中,受到冷空气入侵后变性,从垂直对称分布演变为倾斜的非对称分布,且在北上过程中与中纬度高空锋区作用,但“Matsa”中心嵌入中纬度高空锋区,有再加强过程;而“Wipha”仅外围环流与锋区接触,中心未进入锋区,无再加强过程。通过对大气稳定度和垂直螺旋度等进一步分析表明：“Matsa”变性过程是系统性冷空气的南侵,而Wipha的变性只有弱冷空气的入侵;台风中心所在的垂直涡度ζ_p的增长大值区是否落在△θ_e<0的大气对流性不稳定的区域内,对台风变性后是否再加强有一定影响。此外,垂直螺旋度的高低空配置及正涡度柱与上升运动的相互配合是使台风变性加强的重要因素。  相似文献   

硇洲岛底栖海藻的初步研究     

陈燕  杨秀坚  陈渊 《广东海洋大学学报》1995,(2)

调查了硇洲岛底栖海藻的种类组成、垂直分布特点和区系性质。硇洲岛的海藻计有４３属６７种，其中包括４０种经济海藻。马尾藻属等在潮下带构成环岛的海底林带。其区系性质属亚热带。并对合理开发利用和保护现有的海藻资源，开展经济海藻的人工养殖提出了建议。  相似文献   

Adaptation of the vertical resolution in the mixed layer for HYCOM   总被引：1，自引：0，他引：1  

Ccile Renaudie  Rmy Baraille  Yves Morel  Gwenaëlle Hello  Herv Giordani 《Ocean Modelling》2009,30(2-3):178-189

This paper focuses on the dynamics of the mixed layer. When the mixed layer depth increases, the vertical discretisation eventually becomes too sparse at the bottom of this layer to accurately resolve its evolution and strong numerical errors can appear. This is linked to the fact that the vertical resolution is concentrated in the upper part of the ocean and does not adapt to the deepening of the mixed layer.Knowing that the HYbrid Coordinate Ocean Model (HYCOM) is able to modify the distribution of the vertical levels, we suggest in this paper a method to adapt the resolution to the mixed layer extension. This method is tested in 1-D configurations for two academic atmospheric forcing conditions (strong convection and wind-mixing) and a realistic forcing extending over one year, with seasonal restratification following strong winter convection. The new method improves the results in all cases, and in particular when the mixed layer reaches deep layers.  相似文献   

Dynamics of seasonal recharge beneath a semiarid vegetation on the gnangara mound,Western Australia     

M. L. Sharma  M. Bari  J. Byrne 《水文研究》1991,5(4):383-398

To estimate seasonal changes in recharge to the underlying sandy aquifer, the soil water dynamics of the unsaturated zone was monitored down to a depth of 20 m over a period of three years (1985 to 1987). The measurements were made by a neutron probe at eight locations beneath a native vegetation in a semiarid region, Western Australia, receiving precipitation of 775 mm yr^?1. A relatively simple method, based on the analyses of sequentially measured soil water profiles involving utilization of zero flux plane in the unsaturated zone, is presented and used to compute seasonal recharge rates. Drainage fluxes (recharge rates) below two specified depths were estimated. These were: R₁ (water flux at a depth of 10 m, just below the maximum rooting depth) and R₂ (water flux at a depth of 18 m, just above the water table). These two estimates were significantly different both on a seasonal and annual basis, but their cumulative values for the three year period were very similar. While the annual precipitation varied from 525 to 850 mm yr^?1, the corresponding spatially averaged R₁ varied from 34 to 149 mm yr^?1, and R₂ varied from 65 to 80 mm yr^?1. A significant difference in recharge between the upslope and downslope positions on a hillslope was ascribed to differences in vegetation density of the understorey and differences in hydraulic properties of subsoils. For the three year period, the average R₁ and R₂ were 13 per cent and 10 per cent of the precipitation respectively. These values compare favourably with a long-term estimate based on an environmental tracer technique.  相似文献   

Discretization error for the superposition of Gaussian beams     

Lud&#;k Klime&#; 《Geophysical Journal International》1986,86(2):531-551

Summary. A high-frequency asymptotic integral expansion of a time-harmonic wavefield into Gaussian beams was derived in a previous paper by Klimeš. The discretization error caused by replacing this integral superposition by a discrete summation of Gaussian beams is estimated in this paper.  相似文献   

新疆精河莱历斯高尔铜钼矿床原生地球化学异常     

孙继东  王崇礼  于风池 《地球科学与环境学报》1992,(4)

矿区处于博罗霍洛山主脊,属斑岩型铜钼矿床。斑岩体本身为矿体,钼矿在岩体内,铜矿在外接触带。通过矿区北部勘查地球化学工作表明,Mo、Cu、Pb、Ag、As原生地球化学异常规模大、连续性好,形态规则,梯度大。As、Sb、Ag具前缘特征。除Mo、Cu外,Pb、Ag具主成矿元素特征。原生异常纵向分带具轴向分带特征,分带序列有一定的典型意义。从地质、地球化学异常特征、小岩体地球化学特征以及金属预测资源初步计算认为该矿床很有远景。  相似文献   

Vertical distribution of trace elements in the surface waters offshore Nova Scotia     

Marc Stoffyn 《Estuarine, Coastal and Shelf Science》1984,18(4):433-445

Concentrations of the trace elements Fe, Al, Mn, Cu, Cd, Zn and Ni were measured in shallow vertical profiles (maximum depth 500 m) off the Scotian Shelf in the western North Atlantic. The distributions of the trace elements show variations with depth, the most consistent of which are for Fe and Zn. A minimum concentration near the surface followed by an increase with depth is attributed to in situ mechanisms.  相似文献   

Electrical resistivity surveys to delineate groundwater potential aquifers in Peddavanka watershed,Anantapur District,Andhra Pradesh,India   总被引：1，自引：0，他引：1  

S.?Srinivasa GowdEmail author 《Environmental Geology》2004,46(1):118-131

Vertical electrical resistivity soundings were conducted in order to delineate groundwater potential aquifers in Peddavanka watershed, which is a catchment of about 398 km² in Anantapur District, Andhra Pradesh, India. The main lithologic units in the watershed are quartzite, limestone, shale, and alluvium. Ninety-nine vertical electrical soundings were conducted using the Schlumberger configuration, covering the entire watershed. The data were interpreted with the help of master curves and auxiliary point charts. Interpretations of VES were used to generate a top layer apparent resistivity contour map and longitudinal conductance map. Isoresistivity contour maps were prepared and interpreted in terms of resistivity and thickness of various sub-surface layers using computer software (SURFER), and isocontour diagrams depicting the depth to bedrock were prepared. Resistivity results were correlated with the existing lithology. Based on the depth to bedrock, the thickness of the saturated layer and the resistivity of the second layer, a groundwater potential map has been prepared, in which good, moderate, and poor zones are classified. The study reveals that the weathered and fractured portions in shale and limestone that occur in the southernmost and central portions of the watershed area constitute the productive water-bearing zones categorized as good groundwater potential aquifers.  相似文献   

利用断层自动剖分技术的2008年青海大柴旦Mw6．3级地震InSAR反演研究     

温扬茂  许才军  刘洋  何平 《武汉大学学报(信息科学版)》2012,37(4):458-462,507

2008-11-10青海大柴旦地区发生了Mw6．3级地震,其发震断层位于青藏高原东北缘的大柴旦一宗务隆山断裂带。利用欧空局Envisat／ASAR卫星雷达影像数据,采用二通差分干涉技术获得了地震的同震地表形变场,基于1D协方差函数估计InSAR同震形变场的中误差为0．52cm,方差一协方差衰减距离为5．9km。在此基础上,采用弹性半空间矩形位错模型进行断层几何参数反演,并利用断层自动剖分技术确定了地震的最佳同震滑动分布模型。结果表明,该地震的震源机制解为走向107．19°,倾角56．57°,以逆冲为主兼具少量右旋走滑分量;滑动分布主要发生在10-20km深度范围内,最大滑动量为0．51m,释放的能量为4．3×10^18Nm。  相似文献   

一次罕见飑前强降雹超级单体风暴特征分析   总被引：29，自引：14，他引：15  

戴建华  陶岚  丁杨  王元  陈雷 《气象学报》2012,70(4):609-627

2009年6月5日,受一个飑线前超级单体雷暴的影响,上海部分地区出现了直径25—30mm的冰雹,随后,飑线尾随该超级单体扫过上海,造成大风、雷电和强降水天气。基于常规天气观测、多普勒天气雷达、风廓线仪和自动气象站等资料分析发现,该超级单体发生在东北冷涡西南侧的高空强冷平流与低空暖平流形成的强不稳定层结背景下,超级单体风暴发生、发展在飑线前的暖区中,经过由"热岛效应"和海陆风锋共同形成的低空辐合线时明显加强发展;该风暴呈现出"指"状、"楔"状、弱回波区(WER)等超级单体雷达反射率特征,"指"状回波处出现了中气旋的径向速度特征,具有标志大冰雹的三体散射长钉(TBSS)特征回波,通过三体散射长钉多普勒速度发现了大冰雹的下降区和增长区。分析还表明:东北冷涡西南侧横槽南摆导致中空降温,0℃层和-20℃层高度明显下降,为冰雹的空中增长提供较好的温度环境条件,较低的0℃层也保证冰雹在空中下落中融化较少。双风廓线仪对比观测表明,超级单体发展的低空风场环境中具有较大的垂直风切变和风暴相对螺旋度,中尺度对流系统与环境场的相互作用形成了有利于风暴发展和维持的正反馈机制。飑线前超级单体雷暴与飑线主体关系密切,起到类似"箭"与"弓"的引导作用,飑线主体的一部分进入超级单体所遗留下的"冷"区后明显减弱,东侧入海后也逐渐减弱,其余部分仍在发展加强;最终,强风暴逐渐减弱,超级单体特征也开始消失,飑线与之合并形成新的"人"字型中尺度对流系统,新的"弓"形回波带与原回波带相比移动方向发生右偏,因此,飑前超级单体在飑线主体移动和演变的临近预报中有重要指示意义。  相似文献