鲁西南霾天气个例分析   总被引：4，自引：2，他引：2  

魏秀兰  王玮  范文锋 《气象科技》2008,36(6):724-727

2007年6月11～13日鲁西南连续3天出现罕见的霾天气过程,为了弄清楚这次霾天气过程形成的天气学原因.利用常规气象资料、探空站资料及自动气象站资料和空气污染资料对这次过程进行综合分析.结果表明,霾的形成是多种气象因素共同作用的结果,大陆暖高压东移人海,其底部的偏东气流将海上的低温高湿空气向鲁西南输送,是霾形成的有利环流条件;中低层风速较小,且风向随高度逆转,是霾形成的有利风场;大气层结稳定,且低层存在逆温层是霾形成的重要条件;高污染浓度是形成霾的物质基础.  相似文献   

北京商务中心区大气环境的数值模拟   总被引：1，自引：0，他引：1  

王宝民  刘辉志  桑建国 《气候与环境研究》2007,12(5):604-617

北京商务中心区(Central Business District,CBD)位于北京市中心的东部,距离故宫博物院约4.5km,占地约4km2,最高建筑物超过300m,建成后会导致局地大气环境改变。采用基于k-ε湍流闭合的城市冠层模式对CBD建成后的大气环境进行模拟,结果表明:主导风向西北风时的大气通风能力稍优于次主导风向西南风,空气动力学粗糙度约5.3m,零平面位移约110.0m;浅色建筑外观、屋顶绿化及高叶面指数植被有助于气温的降低,可缓解夏季热岛效应;交通高峰时段,主要道路尤其是交叉路口的NOx浓度超过国家二级标准。上述研究结果对优化CBD规划设计有重要参考价值。  相似文献   

The preservation potential of ash layers in the deep‐sea: the example of the 1991‐Pinatubo ash in the South China Sea     

ANDREAS WETZEL 《Sedimentology》2009,56(7):1992-2009

Following the eruption of Mount Pinatubo on 15 June 1991, volcanic ash was transported westward to the South China Sea in an atmospheric plume, falling out and settling to the sea floor within days and forming an up to 10 cm thick layer on an area >400 000 km². Immediately after deposition, surviving deep‐burrowing animals re‐opened their connection to the sea floor to obtain water for respiration and/or food take‐up. Later, small‐sized meiofauna and then macrofauna re‐colonized the sea floor, mixing newly deposited organic fluff with the underlying ash. Consequently, ash deposits thinner than 1 mm have not often been observed as a continuous layer when cored six years after the eruption, while ash about 2 mm thick is now patchily bioturbated. In areas covered by ash thicker than 5 mm, mixing by benthic animals is controlled mainly by the adaptation of the burrowing fauna to variations in grain‐size, the rate of background sedimentation, the availability of benthic food on and within the sediment and pore water oxygen levels. With respect to these factors, four provinces can be distinguished: (i) Along the Philippines margin run‐off from land fuels primary production that, in turn, leads to a high benthic food content. The benthic fauna is adapted to a variable grain‐size and rapid sedimentation. Therefore, mixing is intense and the preservation potential of the ash layer is low. (ii) In areas affected by deposition of hyperpycnites and turbidites, i.e. in canyons in front of river mouths and in the Manila Trench, the ash layer is preserved due to rapid burial. (iii) The area to the west to about 116° E receives low amounts of benthic food, benthic mixing is less intense and the preservation potential of the ash is high. (iv) The central South China Sea, where the ash is thinner than 3 cm, is affected by intense wind mixing and upwelling and the benthic food content is high; thus, the chance that the ash will be preserved as a sharp‐based layer is low. Consequently, the style of ash preservation has palaeo‐environmental significance. Older buried and burrowed event layers provide further information to elucidate the fate of the 1991 Pinatubo ash layer; in general their appearance fits with observations in the Recent.  相似文献   

A shrinking particle—shrinking core model for leaching of a zinc ore containing silica     

Vida Safari  Gilnaz Arzpeyma  Fereshteh Rashchi  Navid Mostoufi   《International Journal of Mineral Processing》2009,93(1):79-83

A new mathematical model was developed for leaching of zinc ores containing silicates such as hemimorphite which produce a gel during leaching with sulfuric acid. This model is based on the shrinking core model in which the particle size and the reacting core shrink simultaneously. It was shown that the actual dissolution time of the ore particles is longer than the time corresponding to the dissolution of chemical zinc oxide itself. It was suggested that because of the existence of silicates in the ore, a gelatinous layer was formed around the reacting core. Since the gel product is soft, it breaks apart when the particles collide and as a result, the particles shrink. However, a thin gelatinous layer always covers the reacting core which increases the mass transfer resistance and increases the leaching time. This model was applied to leaching of a zinc-rich tailing containing hemimorphite and the thickness of the gelatinous layer as well as the diffusion coefficient in this layer was determined.  相似文献   

关中平原全新世土壤与环境研究     

赵景波  顾静 《地质论评》2009,55(5):753-760

根据蓝田田家村、长安四府村、西安吴家坟和岐山雍川村剖面样品的粒度分析、CaCO3含量测定和微结构的鉴定资料得知,关中平原全新世中期形成的土壤S0具有明显的淀积粘化特征和现代沉积间断条件下发育的土壤剖面特点,该层土壤的构成物质至少有一部分是由先前形成的黄土经成壤作用改造而成的。关中平原S0的粘化类型不仅可以指示当地温湿的气候环境和很少有沙尘暴活动,而且它与西北荒漠区全新世千年尺度上的环境变化存在遥相关关系。全新世晚期发育的黄土L0是在相对冷干条件下形成的狭义土壤,它具有明显的残积粘化和残积—淀积粘化特征,它发育在沙尘暴连续堆积的条件下,形成了厚度大发育弱的粘化层和厚度大而均匀分布的CaCO3淀积层。全新世黄土剖面特征显示,在风尘连续堆积条件下发育的土壤可以不具有明显的剖面分层,厚度可以大于2 m。关中平原全新世L0发育时的气候与西北荒漠区的气候也存在遥相关关系。  相似文献   

大庆长垣南部白垩纪断裂活动及对浅层气藏的控制   总被引：2，自引：0，他引：2       下载免费PDF全文

李建民  付晓飞  玄昌姬  陆延平  刘海涛 《地质科学》2009,44(2):513-524

大庆长垣南部包括葡北、敖包塔和葡两3个局部构造.黑帝庙油层的形成与3种不同演化历史断层有关：反转期断裂（Ⅲ犁）、断陷期形成坳陷期和反转期均活动的断裂（Ⅰ-Ⅱ-Ⅲ型）和坳陷期形成反转期活动的断裂（Ⅱ-Ⅲ型）;其中连通气源岩且活动期与大量生排气期相匹配的Ⅰ-Ⅱ-Ⅲ型和Ⅱ-Ⅲ型断裂是生物气垂向运移的主要通道,Ⅰ-Ⅱ-Ⅲ型断裂是深部CO₂向上运移的主要通道.这些断层均是“似花状”断层组合的边界断层,对倾边界断层控制背斜和鼻状构造形成.数值模拟表明：对倾的气源断层与地层产状的配置关系共同控制天然气运移方向和聚集的部位,由于葡萄花和敖包塔构造西缓东陡,因此天然气主要富集在背斜东翼和背斜之间的断块上.  相似文献   

松辽盆地三肇凹陷葡萄花油层油-水分布规律及控制因素          下载免费PDF全文

柳成志 《地质科学》2009,44(2):545-559

基于近4500口探井和开发井动态及静态资料,对三肇凹陷葡萄花油层平面和纵向油-水分布规律进行了研究,发现南、北区油-水分布存在差异.北区油主要分布在断裂密集带上,断裂带之间的构造低部位断层密度低,主要富集水,垂向上具有下水上油的分布特征;南区油大面积连片,垂向上具有全井纯油的特征.造成这种差异的原因是南、北区断层成因机制不同导致控藏机理的根本不同.北区断裂为构造成因,是在近东两向拉张应力场中受斜向裂陷作用影响形成的张扭断裂密集带,断裂活动诱导超压释放和流体排放,油源供给不足;南区发育非构造成因的多边断层,超握诱导断层活动释放流体,油源供给充足.  相似文献   

复杂储层识别的地震反演方法及其在塔木察格盆地的应用          下载免费PDF全文

陈显森  孙山  张正和  龙江南 《地质科学》2009,44(2):700-706

随着油气藏勘探开发程度的加深,准确识别复杂储层变得愈发重要,地震反演已成为储层预测的核心技术.本文对蒙占国塔木察格盆地南部凹陷1 800 km²地震资料进行波阻抗反演研究,研究工作包括测井曲线的标准化校正、地质框架模型的准确建立及其它反演参数的正确选取.波阻抗反演结果为研究沉积相划分、砂体空问展布的认识提供了可靠依据,在一定程度上解决了该区主要日的层南屯组沉积物源多、相变快和在地震剖面上无法追踪的问题.  相似文献   

地球自由振荡弹性简正模研究进展与展望     

栾威  申文斌  丁浩 《地球与行星物理论评》2021,(3):308-325

在构建现代地球模型时,地球内部分层结构主要是根据地震波资料确定的;而地球内部密度及弹性参数,特别是地幔以下大尺度结构的密度分布,则主要是根据地球自由振荡的弹性简正模观测资料确定的.本文概述了地球自由振荡简正模本征值的求解理论和方法,介绍了球型和环型模态位移场表达式,讨论了地球自由振荡模态的衰减、分裂与耦合效应;总结了多线态分裂谱线探测和分裂参数估计的方法,综述了利用弹性简正模开展地震矩张量、地球三维非均匀性结构和内核超速旋转约束与反演研究的主要进展和存在的问题.最后作为展望,本文还讨论了地球自由振荡简正模的未来研究趋势.  相似文献   

集成Landsat OLI和机载LiDAR条带数据的亚热带森林生物量制图   总被引：1，自引：0，他引：1  

曹林  徐婷  申鑫  佘光辉 《遥感学报》2016,20(4):665-678

以亚热带天然次生林为研究对象,借助一个条带的少量LiDAR点云数据和覆盖整个研究区的免费Landsat OLI多光谱数据,并结合地面实测数据,探索森林生物量低成本高精度制图方法。首先,提取了OLI和LiDAR特征变量,并与地上和地下生物量进行相关分析以筛选变量;然后,借助LiDAR数据覆盖区的样地和条带LiDAR数据构建"LiDAR生物量模型";再从LiDAR反演生物量的结果中进行采样,结合OLI特征变量构建"LiDAR-OLI模型";最后,与单独使用OLI多光谱数据建立的"OLI估算模型"结果进行比较,分析精度并验证新方法的效果。结果表明,"LiDAR-OLI模型"对地上和地下生物量的模型拟合效果较好且均优于"OLI模型",且其交叉验证的精度也较高并优于"OLI模型",从而证明了新方法的可靠性及有效性。本研究为主、被动遥感技术在中小尺度上协同反演森林参数提供了实验基础,也为基于全覆盖免费OLI多光谱数据及条带LiDAR数据的低成本森林生物量制图探索了技术路线。  相似文献