渤海夏季环流的高分辨率海浪-潮汐-环流耦合模式研究   总被引：2，自引：0，他引：2  

夏长水  郭景松  王关锁  陈振华  匡晓迪 《海洋学报(英文版)》2019,38(1):32-37

The Bohai Sea is a shallow semi-enclosed inner sea with an average depth of 18 m and is located at the west of the northern Yellow Sea. The climatological circulation pattern in summer of the Bohai Sea is studied by using a wave-tide-circulation coupled model. The simulated temperature and the circulation agree with the observation well. The result shows that the circulation pattern of the Bohai Sea is jointly influenced by the tidal residual current, wind and baroclinic current. There exists an obvious density current along the temperature front from the west part of the Liaodong Bay to the offshore area of the Huanghe Estuary. In the Liaodong Bay there exists a clockwise gyre in the area north to the 40°N. While in the area south to the 40°N the circulation shows a two-gyre structure, the flow from the offshore area of the Huanghe Estuary to the Liaodong Bay splits into two branches in the area between 39°N and 40°N. The west branch turns into north-west and forms an anti-clockwise gyre with the south-westward density current off the west of the Liaodong Bay. The east branch turns to the east and forms a clockwise gyre with the flow along the east coast of the Liaodong Bay. The forming mechanism of the circulation is also discussed in this paper.  相似文献   

Assessment of 2DH and pseudo‐3D modelling platforms in a large saline aquatic system: Lake Urmia,Iran          下载免费PDF全文

M. Zeinoddini  M. A. Tofighi  A. Bakhtiari 《水文研究》2014,28(18):4953-4970

The main objective of this paper is to provide comparative quantitative examinations on the capabilities of two‐dimensional horizontal and pseudo‐three‐dimensional (3D) modelling approaches for simulating spatial and temporal variability of the flow and salinity in Lake Urmia, Iran. The water quality in the lake has been an environmentally important subject partly because this shallow hypersaline aquatic ecosystem is considered to be one of the largest natural habitats of a unique multicellular organism, Artemia urmiana. This brine shrimp is the major food source for many of the protected and rare shorebirds that visit the lake. A. urmiana can grow and survive in certain ranges of salinity, and their disappearance could lead to an alteration of existing equilibria. The lake has also experienced considerable man‐made changes during the past three decades. A newly built crossing embankment almost divided the lake into two northern and southern halves. A relatively small opening of 1.25 km in the new embankment provides water connections between the two halves. As a result, the flow and salinity regimes have been significantly changed. This might have had adverse serious impacts on the lake ecosystem. In the current study, the two‐dimensional horizontal hydrodynamic model has been found to provide reasonable predictions for the flow regime in the lake, whereas its salinity predictions have not been consistent with the field observations. The pseudo‐3D model has produced results fairly close to the salinity measurements and its temporal and spatial variations. The pseudo‐3D model has been used for evaluating the embankment effects on the lake hydrodynamics and on the salinity conditions. The effectiveness of introducing a different number or length of openings in the embankment for restoring the pre‐embankment conditions has also been examined. These remedy options have been found not to offer substantial improvements to the lake's existing ecosystem. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Using stable isotopes to understand seasonal and interannual dynamics in moisture sources and atmospheric circulation in precipitation          下载免费PDF全文

Yu Tang  Xianfang Song  Yinghua Zhang  Dongmei Han  Likun Ai  Tianbao Zhao  Yajun Wang 《水文研究》2017,31(26):4682-4692

Stable isotopes in precipitation are useful tracers to strengthen understanding of climate change and hydrological processes. In this study, the moisture sources of 190 precipitation events in Beijing were analysed using the Hybrid Single‐particle Lagrangian Integrated Trajectory model, based on which we studied the relation between variations in precipitation δ¹⁸O and dynamics in moisture sources and atmospheric circulation in seasonal and interannual timescales. Categorization of 7 groups of moisture sources was performed, among which oceanic moisture sources presented lower δ¹⁸O in precipitation than continental moisture sources. The results show that seasonal variations of precipitation δ¹⁸O were caused by changes of moisture sources. In summer, moisture from proximal oceans dominated vapour transport to Beijing due to increasing monsoon strength and resulted in a relatively small variation of precipitation δ¹⁸O. At the interannual timescale, the variations of δ¹⁸O in summer precipitation were related to dynamics in oceanic moistures, showing depleted values when the contribution of oceanic moistures, especially the proportion of long‐distance oceanic moisture, was high. Further analysis indicated that changes of oceanic moisture sources were controlled by the strength of summer monsoons. These findings address the complexity of moisture sources in midlatitude monsoon areas and suggest that isotopic signals in precipitation have the potential to deduce changes in moisture sources and atmospheric circulation and can therefore serve for palaeoclimate reconstruction.  相似文献   

《震灾防御技术》第6卷(2011年)总目录     

《震灾防御技术》2011,6(4):478-480

  相似文献   

娄江特大桥深孔泵吸反循环工艺的改进          下载免费PDF全文

张广亮  刘建涛  陈益敏 《探矿工程》2011,38(6):47-50

随着国家基础设施投入的加大,桩径1000－2000 mm、孔深100－130 m的钻孔灌注桩在各类工程中屡被采用。泵吸反循环传统上被用于孔深不超过80 m的深孔,在京沪高铁第六标段娄江特大桥钻孔灌注桩施工中,通过对现有的反循环钻机进行改进,很大程度上提高了泵吸反循环的工作效率,顺利地完成了孔深131 m、桩径1.8 m桩孔的施工,产生了很好的经济效益。  相似文献   

Numerical simulation of nearshore circulation on field topography under random wave environment     

Junwoo Choi  Sung Bum Yoon 《Coastal Engineering》2011

In order to investigate surf zone hydrodynamics through two-dimensional numerical simulations of nearshore circulation under random wave environment, a nearshore circulation model, SHORECIRC, and a random wave model, SWAN, were combined and utilized. Using this combined model, a numerical simulation of the October 2, 1997 SandyDuck field experiment was performed. For this simulation, field topography and an input offshore spectrum were constructed using observed data sets synchronized with the experiment. The wave-breaking model in SWAN was modified by using breaker parameters varied according to bottom slope. The simulation results were compared with the experimental data, which revealed a well-developed longshore current, as well as with results using other combinations which were SHORECIRC and its original monochromatic wave-driver, and SHORECIRC and the default of SWAN. The results from the novel combined model agreed well with the experimental data. The results of the present simulation also indicate that alongshore field topography influences shear fluctuation of longshore currents.  相似文献   

西湖总磷模型构建及内循环引水效果分析          下载免费PDF全文

滑磊  尤爱菊  韩曾萃  腾辉  朱军政 《水文》2015,35(4):27-32

调水是目前快速改善湖泊水质的有效方法之一,但是对于调水所能达到的最佳效果研究很少。以杭州西湖为例,利用环境流体动力学模型EFDC构建了西湖TP模型,对通过苏堤各桥孔的流量、外西湖分层流场和水质浓度进行了验证,分析了在现有外围调水情况下增加西湖内循环引水后西湖TP的时空变化。模拟结果表明,增加内循环引水,直接将低浓度区的水引至高浓度区,能够明显降低高浓度区的水质;低浓度区由于引水量的减小,区域内水质浓度会有一定的上升;全湖平均水质浓度基本不会发生改变。在没有增加外部引水的情况下,内循环引水可以使湖泊水体掺混更加均匀,对于防止高浓度区富营养化有很好的效果。增加内循环引水对西湖改善高浓度区水质有一定的指导意义,同时也可为相似湖泊增加内循环引水措施提供借鉴。  相似文献   

基于LS-DYNA的贯通式潜孔锤反循环钻头强度的优化分析          下载免费PDF全文

李鹏  殷琨  彭枧明  罗永江  李丽佳 《探矿工程》2015,42(3):44-47

通体花键式贯通式潜孔锤反循环钻头在实际施工中尾部较易损坏,影响反循环钻头的使用寿命。为提高反循环钻头的使用寿命,对反循环钻头尾部结构进行了优化设计,并采用非线性动力学仿真软件LS-DYNA对改进前后的反循环钻头进行了仿真分析。分析结果表明：由于在冲锤的高频冲击作用下,反循环钻头尾部易出现较大的局部应力集中,导致钻头体出现疲劳破坏;通过对钻头尾部结构设计优化后,与通体花键式反循环钻头相比,新结构钻头在无泄风槽情况下,应力集中值减小44%,在有泄风槽的情况下,应力集中值减小19%。数值模拟分析表明,优化后能大幅度提高钻头寿命。  相似文献   

What’s in a name? Epistemic perspectives and Payments for Ecosystem Services policies in Nicaragua     

《Geoforum》2015

As Payments for Ecosystem Services (PES) continues to gain attention as a policy tool for securing efficient and effective environmental governance, a rising tide of criticism warns of the potentially detrimental social–ecological consequences of nature commodification and ‘green neoliberalism’. These concerns are also expressed at international policy fora, where the market rhetoric has met with political resistance from countries belonging to the ‘Bolivarian Alliance for the Peoples of Our America’ (ALBA). But despite this ideological opposition, some ALBA countries are increasingly integrating PES into their environmental policies. In this article we consider the reasons underlying this apparent contradiction and relate it to the notion of ‘epistemic circulation’. On the basis of a study on the evolution of PES-thinking in Nicaragua (an ALBA member) and a reassessment of the supposed ‘success’ of an influential pilot project, we shed light on the forces driving the adoption of particular PES modes and contextualise practical difficulties to endorsing more critical approaches to the tool. Instead of either ideologically rejecting PES as a neoliberal evil or embracing it uncritically as the new panacea, we argue that it is precisely through the socio-political processes surrounding environmental governance debates that the application of PES is shaped. In practice, it may either contribute to an imposed and dispossessing form of capitalism, or tend towards a more negotiated and socio-culturally embedded version of it. Only through its reconceptualisation based on political–cultural primacy rather than market-fetishism can PES achieve its true potential within a broader strategy towards improved environmental governance.  相似文献   

2015年4月大气环流和天气分析   总被引：1，自引：1，他引：0  

周康辉  方翀 《气象》2015,41(7):915-920

2015年4月环流特征如下：极涡为偶极型环流,极涡主体位于格陵兰西侧与加拿大之间,另一中心位于亚洲的东北部;两个极涡中心较常年平均偏低4~8 dagpm,乌拉尔山高压脊偏高8~12 dagpm;副热带高压面积偏大、西脊点偏西,南支槽位置与强度接近常年平均;4月全国平均气温11.6℃,较常年同期（11℃）偏高0.6℃;全国平均降水量43 mm,接近常年同期（44.7 mm）,我国中东部长江以北地区降水偏多,江南、华南降水偏少。4月全国强对流天气过程频发,1—4、19—20和28—29日出现了范围较大的强对流天气。北方地区出现2次沙尘天气。  相似文献