The East Greenland Current and its contribution to the Denmark Strait overflow   总被引：8，自引：1，他引：8  

Rudels  Bert; Fahrbach  Eberhard; Meincke  Jens; Budeus  Gereon; Eriksson  Patrick 《ICES Journal of Marine Science》2002,59(6):1133-1154

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Geogrid-based countermeasures against scour behind coastal dikes under tsunami overflow     

Naoki Takegawa  Toshinori Kawabata 《Marine Georesources & Geotechnology》2020,38(1):64-72

Abstract

Following the Great East Japan Earthquake, a massive tsunami caused serious damage to coastal dikes. Local scour at the ground behind these dikes reportedly causes dike failures. It is important to reveal the scour process to establish methods for effective scour countermeasures. Herein, we focus on geogrids. To verify this proposal and examine its design, flume-model experiments were performed for non-liquefied and liquefied grounds behind coastal dikes. The results showed that the scour amount and area were reduced drastically when geogrids were present. Geogrids on the sand-bed surface changed the direction of overflow water. Thus, a scour hole developed away from a coastal dike model. Furthermore, geogrids exerted a scour-reduction effect even during liquefaction.  相似文献   

Numerical investigation of the South China Sea deep circulation     

Shengquan Tang  Xueen Chen  Zhi Zeng  Xin Liu 《海洋学报(英文版)》2022,41(5):1-2

Based on a two-level nested model from the global ocean to the western Pacific and then to the South China Sea（SCS）, the high-resolution SCS deep circulation is numerically investigated. The SCS deep circulation shows a basin-scale cyclonic structure with a strong southward western boundary current in summer（July）, a northeastsouthwest through-flow pattern across the deep basin without a western boundary current in winter（January）,and a transitional pattern in spring and autumn. The sensitivity ...  相似文献   

苏禄海的“通风”过程：历史数据分析     

LI Li  GAN Zijun 《海洋学报(英文版)》2014,33(9):1-11

Based on historical observations, ventilation of the Sulu Sea （SS） is investigated and, its interbasin exchange is also partly discussed. The results suggest that near the surface the water renewal process not only occurs through the Mindoro Strait （MS） and the Sibutu Passage, but also depends on the inflows through the Surigao Strait and the Bohol Sea from the Pacific and through the Balabac Strait from the South China Sea （SCS）. Both inflows are likely persistent year round and their transports might not be negligible. Below the surface, the core layer of the Subtropical LowerWater （SLW） lies at about 200 m, which enters the SS through the Mindoro Strait not hampered by topography. Moreover, there is no indication of SLW inflow through the Sibutu Passage even though the channel is deep enough to allow its passage. The most significant ventilation process of the SS takes place in depths from 20a m to about 1200 m where intermediate convection driven by quasi-steady inflows through the Mindoro and Panay straits （MS-PS） dominates. Since the invaded water is drawn from the upper part of the North Pacific Intermediate Water （NPIW） of the SCS, it is normally not dense enough to sink to the bottom. Hence, the convective process generally can only reach some intermediate depths resulting in a layer of weak salinity minimum （about 34.45）. Below that layer, there is the Sulu Sea Deep Water （SSDW） homogeneously distributed from 1200 m down to the sea floor, of which the salinity is only a bit higher （about 34.46） above the minimum. Observational evidence shows that hydrographic conditions near the entrance of the MS in the SCS vary significantly from season to season, which make it possi- ble to provide the MS-PS overflowwith denser water of higher salinity sporadically. It is hence proposed that the SSDW is derived from intermittent deed convection resulted from DroDertv changes of the MS-PS inflow.  相似文献   

Water column structure and statistics of Denmark Strait Overflow Water cyclones     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

Data from seven moorings deployed across the East Greenland shelfbreak and slope 280 km downstream of Denmark Strait are used to investigate the characteristics and dynamics of Denmark Strait Overflow Water (DSOW) cyclones. On average, a cyclone passes the mooring array every other day near the 900 m isobath, dominating the variability of the boundary current system. There is considerable variation in both the frequency and location of the cyclones on the slope, but no apparent seasonality. Using the year-long data set from September 2007 to October 2008, we construct a composite DSOW cyclone that reveals the average scales of the features. The composite cyclone consists of a lens of dense overflow water on the bottom, up to 300 m thick, with cyclonic flow above the lens. The azimuthal flow is intensified in the middle and upper part of the water column and has the shape of a Gaussian eddy with a peak depth-mean speed of 0.22 m/s at a radius of 7.8 km. The lens is advected by the mean flow of 0.27 m/s and self propagates at 0.45 m/s, consistent with the topographic Rossby wave speed and the Nof speed. The total translation velocity along the East Greenland slope is 0.72 m/s. The self-propagation speed exceeds the cyclonic swirl speed, indicating that the azimuthal flow cannot kinematically trap fluid in the water column above the lens. This implies that the dense water anomaly and the cyclonic swirl velocity are dynamically linked, in line with previous theory. Satellite sea surface temperature (SST) data are investigated to study the surface expression of the cyclones. Disturbances to the SST field are found to propagate less quickly than the in situ DSOW cyclones, raising the possibility that the propagation of the SST signatures is not directly associated with the cyclones.  相似文献   

The Evolution of Massive Close Binaries     

C. De Loore  W. Van Rensbergen 《Astrophysics and Space Science》2005,296(1-4):337-352

We present results of evolutionary computations for massive close binaries with the Brussels simultaneous evolution code for conservative and non-conservative Roche lobe overflow (RLOF). We discuss mass transfer in massive close binaries during phases of RLOF, common envelope, spiral-in and merging. We examine the effects of stellar wind during successive stellar evolution phases and the final fate of primaries. We show how our library can be used to explain well-known binaries such as the WR + OB system V444 Cyg, HMXBs Vela X-1 and Wray 977, LMXBs like Her X-1, and binary pulsars. More details on the evolution of massive close binaries can be found in “The Brightest Binaries” (Vanbeveren et al., 1998).  相似文献   

一种高速网络下IDS溢出数据包的处理模型     

刘本斌  杨天奇 《成都信息工程学院学报》2006,21(2):252-255

对匹配规则和被检数据包，都分为实时在线检测部分和延时离线补检部分，来选择性地溢出一些不重要的包和规则，避免随机丢包。同时把这些溢出的包保存下来，待系统有多余处理能力时，再调出来检测。这样既避免了随机丢包造成的安全隐患，又在没有增加硬件的情况下，提升了系统的检测性能。  相似文献   

Laminated tufa sediments formed from overflow karst springs: Controls on their deposition and carbon–oxygen isotope records          下载免费PDF全文

David Domínguez‐Villar  Juan A. Vázquez‐Navarro  Kristina Krklec  Sonja Lojen  Ian J. Fairchild 《Sedimentology》2017,64(5):1274-1288

Tufa sediments are freshwater carbonates that precipitate in karst regions after degassing of carbon dioxide from groundwater in contact with the atmosphere. When laminated, these carbonates can provide high‐resolution records for the study of climate, hydrological and environmental conditions at the time of their precipitation. The formation of these carbonates directly depends on the hydrological regime, and in karst regions discontinuous discharges are often recorded. This study investigates the record of recent laminated tufa sediments precipitated downstream overflow springs in Trabaque Canyon (central Spain). The hydrological dynamics of the karst system were monitored for over three years and a stable isotope record was obtained from laminated tufa carbonates precipitated from an overflow spring. Additionally, a hydrological model of overflow springs was generated and a tufa δ¹⁸O record under constrained parameters was simulated. Temperature is the dominant control of the variation in tufa δ¹³C and δ¹⁸O values within each lamina, although when comparing different laminae, δ¹³C_DIC and δ¹⁸O of river water are also major controls. The positive correlation between tufa δ¹³C values and water temperature is caused by the fractionation occurred by carbon dioxide degassing due to the thermal dependence of carbon dioxide solubility. Additionally, the system recorded a temperature‐independent degassing process caused by the large gradient between groundwater and atmospheric carbon dioxide that is limited to the proximity of the spring. This study cautions on the risk of assuming continuous deposition when studying laminated tufa sediments and highlights the potential of their stable isotope records to provide hydrological information of their aquifers during the past.  相似文献   

苏州河初期雨水调蓄池控制溢流污染影响研究   总被引：17，自引：0，他引：17       下载免费PDF全文

徐贵泉  陈长太  张海燕 《水科学进展》2006,17(5):705-708

利用苏州河沿岸代表性排水系统雨季溢流水量水质监测以及调蓄池处理技术的实验研究成果,与数学模型研究有机结合,建立了苏州河水系水量水质模型和排水系统概化管网水力模型,系统研究了在8种1~12h设计降雨条件下,苏州河沿岸初期雨水调蓄池控制溢流污染的影响变化及其对苏州河水质的影响。  相似文献   

Assessment of spill flow emissions on the basis of measured precipitation and waste water data   总被引：1，自引：0，他引：1  

Martin Hochedlinger  Günter Gruber  Harald Kainz 《Atmospheric Research》2005,77(1-4):74

Combined sewer overflows (CSOs) are substantial contributors to the total emissions into surface water bodies. The emitted pollution results from dry-weather waste water loads, surface runoff pollution and from the remobilisation of sewer deposits and sewer slime during storm events. One possibility to estimate overflow loads is a calculation with load quantification models. Input data for these models are pollution concentrations, e.g. Total Chemical Oxygen Demand (COD_tot), Total Suspended Solids (TSS) or Soluble Chemical Oxygen Demand (COD_sol), rainfall series and flow measurements for model calibration and validation. It is important for the result of overflow loads to model with reliable input data, otherwise this inevitably leads to bad results. In this paper the correction of precipitation measurements and the sewer online-measurements are presented to satisfy the load quantification model requirements already described. The main focus is on tipping bucket gauge measurements and their corrections. The results evidence the importance of their corrections due the effects on load quantification modelling and show the difference between corrected and not corrected data of storm events with high rain intensities.  相似文献