Characteristics of air flow over Andaman islands including precipitation     

Sarat C. Kar  N. Ramanathan 《Journal of Earth System Science》1987,96(2):169-188

The characteristics of simulated air flow over Andaman Islands are studied with a two-dimensional version of the University of Virginia meso scale model (UVMM). Using the observed synoptic data as initial conditions, 24 hr simulations are obtained for a day each in April and November. These days are chosen to study the variations in the simulated flow pattern under different synoptic conditions including precipitation effects. A large scale condensation scheme is employed to consider the effect of latent heat release on the perturbations. The results show that the latent heat released by condensation strengthens the intensity of perturbations and the topography accelerates the arrival of sea breeze by about an hour. The model-simulated results, given in graphical form, are discussed and compared with available observations.  相似文献   

内蒙古中西部多岛海构造演化   总被引：10，自引：0，他引：10  

高计元  王一先  裘愉卓  张乾 《大地构造与成矿学》2001,25(4):397-404

内蒙古中西部大陆由一个微大陆、三条弧后盆地和三条火山岛弧,即华北微大陆、白云鄂 傅弧后盆地、白乃庙火山岛弧、温都尔庙弧后盆地、苏尼特左－锡林浩特火山岛弧、贺根山弧后盆 地和二连浩特－锡林郭勒火山岛弧组成。经过了长期而复杂的微大陆和火山弧的裂解、弧后盆地 的消减衰亡及弧－陆和弧－弧碰拉等构造演化,才最终形成今天所见到的这种构造样式。  相似文献   

东昆仑万保沟岩群洋岛地层序列特征和构造古地理的恢复     

蔡雄飞  魏启荣 《地层学杂志》2007,31(2):117-125

洋岛地层序列在造山带地区往往十分发育,它们在时间上、空间上具两大特点,时间上往往失序,空间上移位。东昆仑万保沟岩群也有洋岛地层序列通常具有洋岛型火山岩基底和碳酸盐岩盖层的双层式结构,具有低分异度、高丰度和地方性色彩的生物群面貌,因而温泉沟岩组和青办食宿站岩组在时间上具先后、空间上具紧密的关系。  相似文献   

ISLANDS AS NOVELTY SITES*     

GODFREY BALDACCHINO 《Geographical review》2007,97(2):165-174

ABSTRACT. Being on the edge, being out of sight and so out of mind, exposes the weakness of mainstream ideas, orthodoxies, and paradigms and foments alternatives to the status quo. Islands are thus propelled as sites of innovative conceptualizations, whether of nature or human enterprise, whether virtual or real. They stand out as sites of novelty; they tend toward clairvoyance; they are disposed to act as advance indicators or extreme reproductions of what is present or future elsewhere. This article, which is essentially bibliographical, celebrates islands as the quintessential sites for experimentation, with reference to the physical sciences, the social sciences, and literature.  相似文献   

Effect of agricultural land use on the chemistry of groundwater from basaltic aquifers, Jeju Island, South Korea   总被引：2，自引：0，他引：2  

Dong-Chan Koh  Kyung-Seok Ko  Yongje Kim  Seung-Gu Lee  Ho-Wan Chang 《Hydrogeology Journal》2007,15(4):727-743

Geochemical processes were identified as controlling factors of groundwater chemistry, including chemical weathering, salinization from seawater and dry sea-salt deposition, nitrate contamination, and rainfall recharge. These geochemical processes were identified using principal component analysis of major element chemistry of groundwater from basaltic aquifers in Jeju Island, South Korea, a volcanic island with intense agricultural activities. The contribution of the geochemical processes to groundwater chemistry was quantified by a simple mass-balance approach. The geochemical effects due to seawater were considered based on Cl contributions, whereas the effects due to natural chemical weathering were based on alkalinity. Nitrogenous fertilizers, and especially the associated nitrification processes, appear to significantly affect groundwater chemistry. A strong correlation was observed between Na, Mg, Ca, SO₄ and Cl, and nitrate concentrations in groundwater. Correspondingly, the total major cations, Cl, and SO₄ in groundwater were assessed to estimate relative effect of N-fertilizer use on groundwater chemistry. Cl originates more from nitrate sources than from seawater, whereas SO₄ originates mostly from rainwater. N-fertilizer use has shown the greatest effect on groundwater chemistry, particularly when nitrate concentrations exceed 6–7 mg/L NO₃–N. Nitrate contamination significantly affects groundwater quality and 18% of groundwater samples have contamination-dominated chemistry.  相似文献   

广州市冬夏季热岛的空间格局及其差异分析     

王芳  卓莉  冯艳芬 《热带地理》2007,27(3):198-202

利用2003年夏季和冬季两景Landsat ETM图像的热红外波段反演了广州市地表温度(LST)的空间变化,并对冬季和夏季热岛空间分布特征的差异及成因进行了分析。结果表明,广州市冬季和夏季热岛的空间分布具有明显的规律性,并且空间分布、强度差异很大;夏季热岛集中区主要是建筑物和道路等非渗透表面组成地域以及人口最密集区域,冬季热岛的分布主要与工业区和运输业的分布相伴。引起这种差异的原因主要是城市能耗布局、下垫面性质、冬夏季生物学和热学特征综合作用的结果。  相似文献   

南沙群岛岛礁地形地貌TM影像特征分析   总被引：3，自引：2，他引：3  

潘春梅  丁谦  曹文玉 《国土资源遥感》2002,(2):34-37,60

根据南沙海区的地形地貌特征，利用TM图像，对不同的珊瑚礁、珊瑚沙发育状况和岛礁的地质特征与生态特征进行了分析，研究了水下礁、滩的物质组份、发育程度及TM影像特征，提出了30m以浅岛礁分类方法，查清了南沙海域岛、礁、滩、沙的形态和分布，细化并完善了南沙群岛岛礁分类。  相似文献   

从上海市热岛演变看城市绿化的重要意义   总被引：15，自引：6，他引：15  

丁金才  周红妹  叶其欣 《气象》2002,28(2):22-24

近40年来，上海城市热岛面积扩大了7－8倍，强度增强了一倍，导致了高温灾害的增加。上海热岛的迅速扩张和增强始于20世纪80年代，与上海城市的建设有明显的对应关系。如何合理规划城市建设，减缓热岛效应影响，以保证上海城市的健康和可持续发展，已成为一个迫切需要解决的问题。近几年来显示出的上海中心城区热岛强度减弱趋势表明，城市绿化建设对减缓城市热岛效应具有重要意义。  相似文献   

西藏冈底斯岛弧及其铜多金属矿带的基本特征与远景评估   总被引：64，自引：10，他引：64  

王全海  王保生等 《地质通报》2002,21(1):35-40

冈底斯岛弧带属冈底斯活动大陆边缘的组成部分。带内早自中侏罗世、晚至第三纪的中酸性火山岩以及与雅鲁藏布江结合带有成因联系的Ⅰ型中酸性岛弧陆缘碱性侵入体（40-100Ma)和陆内汇聚造山引起的S型花岗岩体（15-50Ma)广泛发育。研究证实，冈底斯岛弧带属有色金属、贵金属成矿带。主要矿种的矿床类型有：海底火山热液型或火山喷流沉积型（Cu多金属）、海底热水沉积型（Cu、Pb、Zn等）、斑岩型（Cu、Mo）以及接触交代岩浆期后地下水热液充填的复合型（Cu、Pb、Zn）等。这些多期、多阶段复合叠加成矿作用和多种矿床类型的“同带共存”格局，展示了冈底斯岛弧带的巨大找矿潜力。  相似文献   

A Simple Single-Layer Urban Canopy Model For Atmospheric Models: Comparison With Multi-Layer And Slab Models   总被引：26，自引：7，他引：26  

Hiroyuki Kusaka  Hiroaki Kondo  Yokihiro Kikegawa  Fujio Kimura 《Boundary-Layer Meteorology》2001,101(3):329-358

We developed a simple, single-layer urban canopy model, and comparedit to both multi-layer and slab models. Our single-layer model has thefollowing features: (a) It is a column model of energy and momentumexchange between an urban surface and the atmosphere, (b) it includesthe influence of street canyons, which are parameterized to representthe urban geometry, (c) it includes shadowing from buildings andreflection of radiation, and (d) it estimates both the surfacetemperatures of, and heat fluxes from, three surface types: roof, wall,and road. In the simulation of the single-layer model, the roof washottest during the daytime, but coolest from midnight to early morning.This is consistent with output from the multi-layer model and fieldobservations at a residential area on a clear, summer day. The diurnalvariation of the energy budget from the single-layer model agrees wellwith that from the multi-layer model. Our single-layer model'sperformance is nearly that of a multi-layer model for studyingmesoscale heat islands. Nevertheless, it is simply parameterized,and thus easily included in larger-scale atmospheric models. The slabmodel has the largest nighttime cooling rate of the three models. Toovercome this, it needs more adjustments than for the canopy models.  相似文献