Gradual entrainment of a chemical layer at the base of the mantle by overlying convection     

Norman H. Sleep 《Geophysical Journal International》1988,95(3):437-447

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Numerical study of high Rayleigh number convection in a medium with depth-dependent viscosity   总被引：1，自引：0，他引：1  

Michael Gurnis  Geoffrey F. Davies 《Geophysical Journal International》1986,85(3):523-542

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Geostatistical analysis of field hydraulic conductivity in compacted clay     

A. S. Rogowski  D. E. Simmons 《Mathematical Geology》1988,20(4):423-446

Hydraulic conductivity(K) of fractured or porous materials is associated intimately with water flow and chemical transport. Basic concepts imply uniform flux through a homogeneous cross-sectional area. If flow were to occur only through part of the area, actual rates could be considerably different. Because laboratory values ofK in compacted clays seldom agree with field estimates, questions arise as to what the true values ofK are and how they should be estimated. Hydraulic conductivity values were measured on a 10×25 m elevated bridge-like platform. A constant water level was maintained for 1 yr over a 0.3-m thick layer of compacted clay, and inflow and outflow rates were monitored using 10×25 grids of 0.3-m diameter infiltration rings and outflow drains subtending approximately 1×1 m blocks of compacted clay. Variography of inflow and outflow data established relationships between cores and blocks of clay, respectively. Because distributions of outflow rates were much less and bore little resemblance to the distributions of break-through rates based on tracer studies, presence of macropores and preferential flow through the macropores was suspected. Subsequently, probability kriging was applied to reevaluate distribution of flux rates and possible location of macropores. Sites exceeding a threshold outflow of 100×10^–9 m/s were classified as outliers and were assumed to probably contain a significant population of macropores. Different sampling schemes were examined. Variogram analysis of outflows with and without outliers suggested adequacy of sampling the site at 50 randomly chosen locations. Because of the potential contribution of macropores to pollutant transport and the practical necessity of extrapolating small plot values to larger areas, conditional simulations with and without outliers were carried out. Simulated scenarios based on all available data compared well with conditional simulations based on randomly chosen locations.This paper was presented at MGUS 87 Conference, Redwood City, California, 14 April 1987.  相似文献   

动态矿区DEM生成方法及其在土地复垦中的应用研究   总被引：2，自引：1，他引：1  

韩奎峰  康建荣 《测绘科学》2009,34(3)

首先根据我国矿区土地复垦工作中存在的不足,通过研究提出"动态土地复垦"的概念,并确定了动态土地复垦方案制定的数据基础——动态矿区数字高程模型。动态矿区数字高程模型应该包含煤矿生产对地表的累积影响结果数据和地表的原始地形信息,开采沉陷预计结果可以提供前者,地面测量可以提供后者,经过数据处理可以按时间间隔生成描述塌陷区的一系列数字高程模型(DEM)(准动态),然后运用DEM的空间分析技术提取塌陷区在不同时间段的土地破坏类型、范围和位置数据,并根据这些数据进行动态土地复垦方案决策数据的提取,经实例验证该方法可行。  相似文献   

登陆孟加拉湾风暴结构个例分析与数值模拟   总被引：1，自引：0，他引：1  

王曼  李华宏  段旭  刘建宇 《气象科技》2009,37(1):12-18

采用NCEP-NCAR再分析资料,分析了2006年4月29日登陆缅甸并造成云南省强降水过程的孟加拉湾风暴结构。并且利用美周新一代中尺度WRF（weather Researchand Forecast）模式对2006年4月28～30日云南强降水过程进行了数值模拟研究。结果表明：孟加拉湾风暴登陆前后结构具有明显变化,从基本对称结构演变为非对称结构,WRF模式较好地模拟出盂加拉湾风暴登陆前后环流场特征和风暴移动路径以及造成云南强降水雨带的分布特征。  相似文献   

Numerical simulation on the evolution of cloud particles in 3-D convective cloud   总被引：2，自引：0，他引：2  

XiaoLi?LiuEmail author  ShengJie?Niu 《中国科学D辑(英文版)》2009,52(8):1195-1206

A 3-D convective cloud model with compressible non-hydrostatic dynamics and the spectral bin microphysics of a 2-D slab-symmetric model has been used to simulate an observed supercell storm occurring on 29 June, 2000 near Bird City, Kansas, USA. The main objective of this paper is to study the evolution of particles in this convective storm with bin spectral microphysics scheme. Graupels form and grow through two mechanisms, deposition and riming, with the riming process dominant on top of the inflow and in the upper portion of main updraft. Over the outflow and during the developing and mature stages of the storm, graupel particles mainly grow through deposition with dominant unimodal spectra. Most fall out after growing up. Reducing initial relative humidity disturbance (increasing initial potential temperature disturbance) has negative impact on the formation and growth of graupels over the inflow (outflow). This study shows that large graupel and hail could be suppressed by altering the deposition and coalescence process over the inflow and main updraft. At different locations of the convective cells and with different initial humidity and potential temperature disturbance, the graupel formation and growth mechanisms are different, so as to the feasible hail suppression locations and methods. Supported by National Natural Science Foundation of China (Grant Nos. 40537034, 40805057), and Foundation of Key Laboratory of Meteorological Disaster of Ministry of Education in Nanjing University of Information Science & Technology (Grant No. KLME060202)  相似文献   

Intraseasonal variability in the equatorial Atlantic-West Africa during March–June     

Guojun Gu 《Climate Dynamics》2009,32(4):457-471

Intraseasonal (30–80 days) variability in the equatorial Atlantic-West African sector during March–June is investigated using various recently-archived satellite measurements and the NCEP/DOE AMIP-II reanalysis daily data. The global connections of regional intraseasonal signals are first examined for the period of 1979–2006 through lag-regression analyses of convection (OLR) and other dynamic components against a regional intraseasonal convective (OLR) index. The eastward-propagating features of convection can readily be seen, accompanied by coherent circulation anomalies, similar to those for the global tropical intraseasonal mode, i.e., the Madden–Julian oscillation (MJO). The regressed TRMM rainfall (3B42) anomalies during the TRMM period (1998–2006) manifest similar propagating features as for the regressed OLR anomalies during 1979–2006. These coherent features hence tend to suggest that the regional intraseasonal convective signals might be mostly a regional response to, or closely associated with the MJO, and probably contribute to the MJO’s global propagation. Atmospheric and surface intraseasonal variability during March–June of 1998–2006 are further examined using the high-quality TRMM Microwave Imager (TMI) sea surface temperature (SST), columnar water vapor, and cloud liquid water, and the QuikSCAT oceanic winds (2000–2006). Enhanced (suppressed) convection or positive (negative) rainfall anomalies approximately cover the entire basin (0°–10°N, 30°W–10°E) during the passage of intraseasonal convective signals, accompanied by anomalous surface westerly (easterly) flow. Furthermore, a unique propagating feature seems to exist within the tropical Atlantic basin. Rainfall anomalies always appear first in the northwestern basin right off the coast of South America, and gradually extend eastward to cover the entire basin. A dipolar structure of rainfall anomalies with cross-equatorial surface wind anomalies can thus be observed during this evolution, similar to the anomaly patterns on the interannual time scale discovered in past studies. Coherent intraseasonal variations and patterns can also be found in other physical components.

Guojun GuEmail:

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塔北地区构造和演化特征及其对油气成藏的控制   总被引：8，自引：0，他引：8  

安海亭  李海银  王建忠  都小芳 《大地构造与成矿学》2009,33(1)

塔北隆起为塔里木盆地最富有油气的构造单元之一,其纵向上可分为中新生界和古生界两大构造层,上下特征有较大的差异性:古生界受到六条基底逆断层及其伴生断裂控制,构造格局可以划分为"四隆两凹"的构造单元:英买力低凸起、轮台低凸起、哈拉哈塘凹陷、轮南低凸起、草湖凹陷以及库尔勒鼻隆,该格局长期继承性发育,并逐层遭受剥蚀形成整个塔北残余古隆起,其上构造圈闭十分发育,同时由于暴露时间长,碳酸盐岩储层非常发育;中新生界整体上表现为南高北低的北倾斜坡形态,受到下伏古生界断层的后期活化影响,发育局部圈闭。塔北当前的构造格局在演化过程中主要形成于海西期,后期变化较小。研究表明,塔北地区构造演化大致经历了三大阶段:晚加里东-早海西期的稳定抬升剥蚀期,塔北在南倾的大斜坡背景上形成了北东-南西走向的轮南大型背斜,英买力低凸起初具雏形;晚海西-印支期的挤压抬升期,塔北隆起在原背景之上继承发展;燕山-喜山期为调整定型期,形成现今塔北地区构造格局。整体古生界构造格局形成早,稳定时间长,是库车油气和满加尔油气的长期指向区,控制了塔北地区油气分布,而多期的构造演化则控制了塔北地区油气藏不同时期的破坏和形成,也造就了目前塔北地区同时存在沥青、稠油、轻质油和天然气。  相似文献   

北疆沙尔布尔提山地区早泥盆-早石炭世沉积相、物源演变及其意义   总被引：3，自引：1，他引：2  

卫巍  庞绪勇  王宇  徐备 《岩石学报》2009,25(3):689-698

准噶尔西北部沙尔布尔提山地区下泥盆统到下石炭统的沉积可划分为滨海相和海岸平原相。其中下泥盆统和布克赛尔组底部的乌图布拉克亚组为滨海碎屑岩相,曼格尔亚组为滨海碎屑岩和碳酸盐岩相,芒克鲁亚组为滨海碳酸盐岩相。中泥盆统呼吉尔斯特组为海岸平原相。上泥盆统洪古勒楞组底部为海岸平原相,向中部过渡为滨海碳酸盐岩相,顶部为滨海碎屑岩相。下石炭统黑山头组为滨海碎屑岩相。下泥盆统和下石炭统的古流向总体从北向南,显示研究区以北地区为物源区,即成吉斯-塔尔巴哈台褶皱带。结合沉积相的研究成果,本区可能属成吉斯-塔尔巴哈台褶皱带以南的晚古生代陆缘区。物源演变趋势分析揭示早泥盆世成吉斯-塔尔巴哈台带中的早古生代岛弧发生隆起,为乌图布拉克亚组提供成熟度很低的碎屑物质。随着岛弧被剥蚀殆尽,中、晚泥盆世呼吉尔斯特组和洪古勒楞组沉积时转而接受岩屑型再旋回造山带的物源供应,而早石炭世的物源则为过渡型再旋回造山带区。这种物源变化反映了成吉斯-塔尔巴哈台褶皱带的建造特征和隆起过程。  相似文献   

鄂尔多斯盆地东南缘延长组成岩作用及储层物性特征          下载免费PDF全文

田亚铭  施泽进  王长城  宋江海  王勇  汪见辉 《沉积与特提斯地质》2009,29(4):47-51

通过成岩作用及储层物性的综合分析,该区主要油层组长9、长8、长6及长2的岩石成分成熟度和结构成熟度均较差,均经历了晚成岩A期。压实作用降低了储层的孔隙度,致密的碳酸盐岩胶结降低了孔隙度并阻止了次生孔隙的产生。该区储层为低孔低渗储层,孔隙度在4％-8％之间,渗透率多小于0．1×10^-3μm2。  相似文献