巴丹吉林沙漠横向沙山的研究现状与问题

处于我国西北内陆干旱荒漠地带的世界最高大的沙丘系统——巴丹吉林沙漠横向沙山系统,具有重要的风沙地貌与沙漠第四纪地质及水文学研究价值。以往的研究主要取得了对该沙漠及其沙山的近130 ka来环境变化历史的框架性认识。沙漠的形成时代、沙源、沙山及其间湖泊的成因与演化过程等及其与区域及全球气候环境变化的关系需要进一步研究。在研究方法上,需要重视沉积学方法的应用。对这些问题的深入研究,不仅对认识其自身奥秘,促进风沙地貌学与沙漠第四纪地质学的进展,而且对认识区域气候、环流、水循环、大地构造等重大环境问题具有重要作用。     

2050年前长江流域极端降水预估

20世纪90年代长江流域日最大降水增加主要出现在长江以南地区和金沙江流域,ECHAM5/MPI-OM模型也大致模拟出了这种趋势。在IPCC给出的3种不同的排放情景下,2000-2050年长江上游日最大降水均有上升趋势,2020年前A2情景下日最大降水最大,A1B最小;长江中下游日最大降水在2025年之前均有明显上升趋势,之后略有下降,波动较大。长江流域未来日最大降水增多的区域可能主要出现在长江以南地区,而极端降水减少的区域可能出现在长江以北地区。     

京津以南河北平原地下水位下降驱动因子的定量评估

自1970年代以来,在自然因素和人为活动的交互影响下,京津以南河北平原地下水位持续下降并产生了一系列地质环境问题,严重影响了该区域社会经济的可持续发展。本文从降水、地表径流、气温等自然因素及地下水超采、水利工程修建、农作物产量水平提高、耗水型作物面积扩大等人为因素初步分析了京津以南河北平原地下水位下降的主要原因;通过建立投影寻踪回归模型,定量评价了各因素对地下水位下降的影响,确定了各影响因素对地下水位下降的相对贡献率。结果表明:地下水开采是引起地下水位下降的最主要因素,对地下水位下降的相对贡献率为54.7%,其中工业、农业、生活用水对地下水位下降的相对贡献率分别为6.6%、43.7%和4.4%;其次是降水和地表径流,其相对贡献率分别为25.6%和19.7%。     

浅层三维横波地震勘探方法研究

通过对横波传播规律及运动形式的数学模型、物理模型及实测数据的研究,发现横波与纵波一样具有三维波场的特性,利用横波的这一特点就可以进行三维横波的野外观测。经大量实际资料表明,利用三维横波资料可以解释埋于地下5~40 m深度范围内的空洞及古巷道,同时能对地层进行精确地分层。      

特长跨海大桥安全监测方法的研究

在特长跨海大桥施工定位与安全监测工作中经常遇到难以克服的困难,为此人们不得不借助于RTKGPS技术.当然,跨海大桥的安全监测问题单纯利用RTK GPS技术是远远不够的,因为跨海大桥安全监测的精度要求远远高于施工定位,不采取一定的技术措施很难实现对跨海大桥运营安全的有效监测.为了较好地解决特长跨海大桥的安全监测问题,笔者与科研小组结合实践提出了通过合理布设三维控制基准系统实施跨海大桥运营安全有效监测的想法,三维控制基准系统的构建应综合考虑投影问题、网形结构问题、施测方法问题,结合我国目前在建的几座跨海大桥论述了跨海大桥安全监测三维控制基准系统构建的基本设计思路.     

地图投影变换网络服务的构建与实现

本文主要从选择地图投影变换方法、地图投影变换功能组件式设计与开发、地图投影变换网络服务的创建及访问入手,深入分析并研究了地图投影网络服务的构建与实现的关键技术,并通过创建桌面和网络两种应用程序进行服务访问与调用,经实验验证了地图投影变换网络服务的发布与共享能快速提高开发效率。     

数字地质图的特点及制图时应注意的几个问题

随着GIS技术引进地质领域,数字地质图全面取代了传统地质图。它克服了模拟地质图的缺欠,可快捷地实现投影变换、随意确定比例尺、任意选择显示范围、选取内容及内容的表达方式等,是今后地质成果的重要表现形式。     

Model Evaluation and Projection on the Linkage between Hadley Circulation and Atmospheric Background Related to the Tropical Cyclone Frequency over the Western North Pacific

The performance of climate models in simulating the linkage of the spring Hadley circulation (HC) to the vertical zonal wind shear and atmospheric divergence in the lower and upper troposphere, which are related to the tropical cyclone frequency over the western North Pacific (WNPTCF) during June-September (JJAS), is evaluated on the basis of the 20th century climate simulations (20C3M). It is found that four models can simulta-neously reproduce the pattern revealed in the observation, with the spring HC in the Northern Hemisphere being positively correlated to the vertical zonal wind shear in the major tropical cyclone (TC) genesis region and negatively (positively) correlated to the atmospheric diver- gence in the upper (lower) troposphere over the western North Pacific (WNP) in the following JJAS. These four models are further used to project their relationship in the late 21st century under the A1B scenario. The results show that the association of spring HC with the vertical zonal wind shear and the upper-and lower-tropospheric divergence over the WNP will weaken in the late 21st century, thereby resulting in a weak relationship between the spring HC and the JJAS WNPTCF.     

2016～2017年凌汛期黄河内蒙河段快速封河的天气成因分析

利用常规观测资料,对2016年11月2023日内蒙河段强降温天气过程进行诊断分析。结果表明:造成这次快速封河的强降温天气过程,与贝湖附近的横槽转竖密切相关。500h Pa上由里海到西西伯利亚平原上空有高压脊强烈发展,脊崩溃是横槽转竖及强冷空气向南爆发的预报着眼点。随着高空横槽转竖并南下,从地面冷高压主体分裂出来的小高压不断东移南下影响内蒙河段。低层冷槽在移动过程中不断加强,并在偏北风急流作用下产生强冷平流,加剧了内蒙河段的温度梯度,共同造成了本次内蒙河段强冷空气天气过程。当北西伯利亚低地出现大量冷空气堆积,且有典型天气形势配合冷空气活动时,要考虑内蒙地区将有强降温过程;如遇内蒙河段河道流量较小,在沿河各站48h降幅达到寒潮标准,最大降幅在14℃以上时,要考虑内蒙河段从流凌到封河的历时将会较短。     

A detailed study of the Gagua Ridge: A fracture zone uplifted during a plate reorganisation in the Mid-Eocene

Recent multibeam bathymetric and geophysical data recorded in the West Philippine Basin, east of Taiwan, reveal new information on the structure and the tectonic origin of the oceanic Gagua Ridge. This linear, 300 km-long, 4 km-high, north-south-trending ridge, is being subducted beneath the Ryukyu Trench along 123° E. This basement high separates two basins of different ages. Its summit is marked by two crests and an axial valley. A map of the basement top shows the region of the ridge to be composed of a set of linear and parallel ridges and troughs. All these elements suggest that the development of the ridge, and its surroundings, has been influenced by strike-slip deformation. Nevertheless, the height of the ridge indicates also an important compressive component in the deformation. Gravity models across the ridge show local compensation with a crustal root, indicating that an overthickening of the crust occurred when it was young and thus more easily deformable. This idea is strengthened with flexural modeling of the lithosphere that bends under the load of the ridge, indeed it indicates that the high probably formed when the underlying lithosphere was young. We interpret the Gagua Ridge as a fracture zone transverse ridge uplifted during a transpressive episode along a north-south -trending fracture zone in the middle Eocene time, if we accept Hilde and Lee's (1984) model of magnetic lineations. This tectonic event could be contemporaneous with a change of the pole of rotation of the West Philippine Basin which occurred about 43/45 Ma ago.