Gravity and magnetic data inversion for 3D topography of the Moho discontinuity in the northern Red Sea area, Egypt   总被引：1，自引：0，他引：1  

Ilya Prutkin  Ahmed Saleh 《Journal of Geodynamics》2009,47(5):237-245

The main goal of our study is to investigate 3D topography of the Moho boundary for the area of the northern Red Sea including Gulf of Suez and Gulf of Aqaba. For potential field data inversion we apply a new method of local corrections. The method is efficient and does not require trial-and-error forward modeling. To separate sources of gravity and magnetic field in depth, a method is suggested, based on upward and downward continuation. Both new methods are applied to isolate the contribution of the Moho interface to the total field and to find its 3D topography. At the first stage, we separate near-surface and deeper sources. According to the obtained field of shallow sources a model of the horizontal layer above the depth of 7 km is suggested, which includes a density interface between light sediments and crystalline basement. Its depressions and uplifts correspond to known geological structures. At the next stage, we isolate the effect of very deep sources (below 100 km) and sources outside the area of investigation. After subtracting this field from the total effect of deeper sources, we obtain the contribution of the Moho interface. We make inversion separately for the area of rifts (Red Sea, Gulf of Suez and Gulf of Aqaba) and for the rest of the area. In the rift area we look for the upper boundary of low-density, heated anomalous upper mantle. In the rest of the area the field is satisfied by means of topography for the interface between lower crust and normal upper mantle. Both algorithms are applied also to the magnetic field. The magnetic model of the Moho boundary is in agreement with the gravitational one.  相似文献   

黑河流域降水的研究进展与展望   总被引：5，自引：0，他引：5  

李海燕  王可丽  江灏  于涛 《冰川冻土》2009,31(2):334-341

归纳总结了黑河流域降水方面已有的研究成果,主要集中在流域降水的时空变化规律及降水的影响因子分析两个方面.在降水变化研究方面,对整个流域降水的时空变化特征与上游祁连山区降水的变化特征分析已有不少工作;在降水影响因子研究方面,对上游祁连山区地形与降水的关系研究在逐步开展;水分条件,气候变化、人类活动与流域降水的关系研究也取得了一些进展.这些研究使我们对流域的气候特征、降水分布情况及降水的地形影响等方面有了一定的了解.为更全面、深入地研究黑河流域降水机理奠定了基础,但仍需在以下两个方面展开深入细致地研究:1)与大尺度环流系统变化有关的水汽来源及输送对黑河流域降水的影响;2)与地形有关的局地因子对黑河流域降水的影响.  相似文献   

Downwelling and upwelling regimes: Connections between surface fronts and abyssal circulation     

Carol Anne Clayson  Maria Luneva  Philip Cunningham   《Dynamics of Atmospheres and Oceans》2008,45(3-4):165

Recent observations in the Sea of Japan show evidence of convection to a depth of roughly 1000 m in the winter of 2000, situated along the polar front. Numerical simulations have shown that this deep mixing is associated with both ageostrophic frontal circulations and pre-existing larger-scale downwelling regimes. The downwelling regimes appear to be a result of interactions between frontal meandering and deep circulation in this basin over bottom topography anomalies. The coupling between the frontal dynamics and the deep circulation are explored by analogy to atmospheric frontal circulations through the semigeostrophic Sawyer–Eliassen equation, solved numerically for the case of the Sea of Japan. As in the atmospheric case, a vertical coupling between the upper and lower circulations can produce a localized region of downwelling that can be conducive to deeper mixing than that forced solely from surface fluxes.  相似文献   

二维起伏地表直流电场插值法数值模拟   总被引：3，自引：1，他引：2  

张东良  孙建国  孙章庆 《世界地质》2009,28(2):242-248

本文提出了一种采用插值法实现边界条件的有限差分数值模拟新方法, 地表函数通过三次样条插值能很好的拟合真实地表形状。其地表边界条件的实现思想是在地表法线方向上寻找一个与地表点位于同一等位线上的点, 该点通过周围点插值来建立离散方程。采用不规则四边形距离加权插值法使插值形式统一化。在水平地表情况下做的数值解与解析解的对比分析表明: 该方法的计算精度适合要求, 对山谷模型的实例计算也得到了视电阻率与地形成镜像对称的结果。  相似文献   

海底地形数据获取的手段、精度和用途     

杜明成 《中国勘察设计》2009,(9):64-69

论述了当前海底地形数据获取的主要方法,根据各种不同方法的特点分析了其可能达到的精度,由此得出各种海底地形数据获取的方法适用性。  相似文献   

浅海海底地形变迁对海上平台动力特性的影响   总被引：1，自引：0，他引：1  

李伟  杨永春  王津 《海洋科学进展》2005,23(3):363-367

海上平台在服役期间,由于周围自然环境以及水动力条件的改变,使得其所在海域地形条件与设计时相比有较大的变化,这势必会对平台的动态响应产生影响。以老黄河口海域埕岛“中心1号”生活平台为例,通过现场实测和数值计算,分析了海底地形变迁对海上平台动力特性所产生的影响,为该海域未来平台的设计和施工提供参考。  相似文献   

Spatial and temporal variation of diverse inter‐tidal algal assemblages in Southwest O‘ahu          下载免费PDF全文

Traci Erin Cox  Heather L. Spalding  Michael S. Foster 《Marine Ecology》2017,38(3)

Spatial and temporal variation in tropical inter‐tidal communities is poorly known, making predictions about the effects of climate change and other anthropogenic disturbances difficult. Along Southwest O‘ahu, Hawai'i, local residents are concerned about the environmental effects of coastal development and the perceived loss of targeted algal species, which are collected for human consumption. To describe the coastal benthic community and better understand the processes that form and maintain it, the abundance and composition of macroalgae were sampled in the region's inter‐tidal zone from 2006 to 2015. Sixty‐six macroalgal species and two broad algal assemblages were identified that corresponded to substrate topography and sand influence at a similar tidal elevation. Along flat carbonate benches with a sand beach, Phaeophyceae and Rhodophytes occurred in almost equal proportions, while shores with slightly more topographic relief and angular substrate were dominated by Rhodophytes. Foliose or turf algal forms were most common. Surveys captured the local invasion of an alga, Avrainvillea sp. and significant declines in abundant macroalgae in 2015 after a period of unseasonably warm, calm water. Temporal changes in algal assemblages were related to maximum water temperature and wave height but not precipitation. Thus, algal assemblages appear to be structured by local beach morphology as they interact with sand and wave activity and episodically by unusual weather events. However, manipulation and continuous monitoring of the algal assemblages coupled to sensing of the localized environment is necessary to confirm factors related to assembly maintenance and recent species shifts.  相似文献   

基于经验模态分解削弱多波束残余误差的方法          下载免费PDF全文

赵祥鸿  暴景阳  黄辰虎  黄贤源  陆秀平 《海洋通报》2017,36(6):662-667

针对多波束水深数据中存在的系统性残余误差,提出了基于经验模态分解方法来削弱残余误差的方法:首先利用经验模态分解方法对多波束测深数据作一维分解,将非线性、非平稳的多波束测深数据分解成准线性子波,然后构建水深数据趋势项与残余项,利用中央波束趋势项建立整体数据趋势项,最后加以水深数据残余项还原海底地形,削弱残余误差影响。通过实测多波束测深数据验证方法的有效性。  相似文献   

波流作用下大直径淹没圆柱局部冲刷试验研究          下载免费PDF全文

程永舟  吕行  王文森  黄筱云  夏波 《水科学进展》2019,30(6):872-881

水下大直径淹没圆柱在波流共同作用下的冲刷特性与非淹没情况有较大差别。在波流水槽中开展局部冲刷试验,将大直径淹没圆柱模型安装在中值粒径0.22 mm的平底沙床内,改变波浪波高和周期、水流流速和方向、圆柱淹没率,测量圆柱周围流速变化,记录柱周冲深发展历时,运用激光地形仪测量冲刷坑的地形形态,分析了淹没率S_r和相对高度h_c/D对准平衡冲深的影响。结果表明,相同入射波流条件下,随相对柱高h_c/D降低,冲刷发展速率、冲坑半径和深度都随之减小。当相对柱高h_c/D>1时,冲深随柱高增长速率较快直至达到临界值。准平衡冲刷坑呈"倒勺状",沿圆柱左右两边呈对称分布,柱前呈半环状;圆柱正后方淤积成"马鞍状"沙丘。  相似文献   

横观各向同性凸起地形对平面qP-qSV波的散射     

巴振宁  周旭  梁建文 《岩土力学》2019,40(1):379-387

  相似文献