A study of estuarine flow using the roving adcp data     

Kiryong Kang  Daniela Di Iorio 《Ocean Science Journal》2008,43(2):81-90

A study of estuarine flows during a neap tide was performed using 13-hour roving acoustic Doppler current profiles (ADCP) and conductivity-temperature-depth (CTD) profiles in the Altamaha River estuary, Georgia, U.S.A. The least-squared harmonic analysis method was used to fit the tidal (M₂) component and separate the flow into two components: the tidal and residual (M₂-removed) flows. We applied this method to depth-averaged data. Results show that the M₂ component demonstrates over 95% of the variability of observation data. As the flow was dominated by the M2 tidal component in a narrow channel, the tidal ellipse distribution was essentially a back-and-forth motion. The amplitude of M2 velocity component increased slightly from the river mouth (0.45 m/sec) to land (0.6 m/sec) and the phase showed fairly constant values in the center of the channel and rapidly decreasing values near the northern and southern shoaling areas. The residual flow and transport calculated from depth-averaged flow shows temporal variability over the tidal time scale. Strong landward flows appeared during slack waters which may be attributed to increased baroclinic forcing when turbulent mixing decreases.  相似文献   

翡翠贻贝三个野生群体的生化遗传分析     

黄荣莲  李康  杜晓东 《海洋通报》2008,27(1):42-47

采用聚丙烯酰胺梯度凝胶垂直平板电泳对湛江、北海和汕尾三地翡翠贻贝(Perna viridis)野生群体10种同工酶21个的位点的生化遗传特性进行分析.分析结果表明8个位点(Alp-1, Alp-2, G6pdh-1, Me-1, Me-2, Sdh-1, α-Est-5, β-Est-2)具有多态性.湛江、北海、汕尾群体的多态位点比例分别为0.381,0.286,0.381,平均期望杂合度分别为0.6 097, 0.5 407和 0.6 893.群体内杂合度较高,遗传多样性较丰富.群体间的基因分化系数在 0.0 140 ～ 0.0 389 范围内,北海和湛江群体间,湛江和汕尾群体间以及北海和汕尾群体间的遗传相似性分别为0.9 838,0.9 861 和 0.9 630; 聚类分析表明湛江和汕尾群体遗传距离极小,而与北海群体分歧稍明显.上述的结果表明,翡翠贻贝 3 个群体种质资源遗传多样性依然处于良好状态.  相似文献   

Analytical theory for one‐dimensional consolidation of clayey soils exhibiting rheological characteristics under time‐dependent loading     

Kang‐He Xie  Xin‐Yu Xie  Xi‐Bin Li 《国际地质力学数值与分析法杂志》2008,32(14):1833-1855

This paper presents analytical solutions to the one‐dimensional consolidation problem taking into consideration the rheological properties of clayey soil under variable loadings. A four‐element rheological model is introduced, and different loading types are involved, i.e. constant loading, one‐step loading, triangular loading, rectangular loading, and isosceles–trapezoidal cyclic loading. The differential equations governing consolidation are solved by the Laplace transform. Based on the solutions obtained, the influences of the rheological parameters and loading conditions on the consolidation process are investigated. It has been shown that the consolidation behavior is mainly governed by four dimensionless parameters, a₁, a₂, b, and T_v0. Load shape has a great influence on the rate of consolidation. A decrease either in the modulus of the spring in the Kelvin body or in the viscosity coefficient of independent dashpot will slow down the rate of consolidation. An increase in the viscosity coefficient of the dashpot in the Kelvin body will make the rate of consolidation increase at an early stage but decrease at a later stage. For isosceles–trapezoidal cyclic loading, the consolidation rate in each cycle reaches a maximum at the end of the constant loading phase and the minimum at the end of this cycle. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Monitoring glacier and supra-glacier lakes from space in Mt. Qomolangma region of the Himalayas on the Tibetan Plateau in China   总被引：6，自引：2，他引：4  

Alfred Stein 《山地科学学报》2009,6(3):211-220

Because of the large number and remoteness, satellite data, including microwave data and optical imagery, have commonly been used in alpine glaciers surveys. Using remote sensing and Geographical Information System （GIS） techniques, the paper presents the results of a multitemporal satellite glacier extent mapping and glacier changes by glacier sizes in the Mt. Qomolangma region at the northern slopes of the middle Himalayas over the Tibetan Plateau. Glaciers in this region have both retreated and advanced in the past 35 years, with retreat dominating. The glacier retreat area was 3.23 km2 （or o.75 km^2 yr^-1 during 1974 and 1976, 8.68 km^2 （or 0.36 km^2 yr^-1 during 1976 and 1992, 1.44 km^2 （or 0.12 km^2 yr^-1） during 1992-2ooo. 1.14 km^2 （or 0.22 km^2 yr^-1 during 2000-2003, and 0.52 km^2 （or 0.07 km^2 yr^-1 during 2003-2008, respectively. While supra-glacier lakes on the debris-terminus of the Rongbuk Glacier were enlarged dramatically at the same time, from 0.05 km^2 in 1974 increased to 0.71 km^2 in 2008, which was more than 13 times larger in the last 35 years. In addition, glacier changes also showed spatial differences, for example, glacier retreat rate was the fastest at glacier termini between 5400 and 5700 m a.s.l than at other elevations. The result also shows that glaciers in the middle Himalayas retreat almost at a same pace with those in the western Himalayas.  相似文献   

Croll revisited: Why is the northern hemisphere warmer than the southern hemisphere?     

Sarah M. Kang  Richard Seager  Dargan M. W. Frierson  Xiaojuan Liu 《Climate Dynamics》2015,44(5-6):1457-1472

  相似文献   

中国海水养殖碳汇经济价值时空演化及影响因素分析     

孙康  崔茜茜  苏子晓  王雁楠 《地理研究》2020,39(11):2508-2520

中国是全球海水养殖第一强国,养殖产量占世界总产量的70%以上。根据碳税法和人工造林法测算海水养殖碳汇经济价值,并探讨时空分异特征;采用LMDI指数分解法,分析海水养殖业碳汇能力影响因素。研究结果表明：① 2008—2017年碳汇量和经济价值均呈上升趋势,2017年经济价值达到91.8亿元;各省碳汇效率排名波动较大,效率和经济价值相对差异和绝对差异逐渐缩小,经济价值处于持续增长趋势。② 时空演化上,经济价值呈现出泛环渤海、泛长三角、泛珠三角三足鼎立分布态势,时空演化揭示了中国碳汇渔业在科学引导,合理布局,陆海统筹,试点先行,全国推广的演化机理,表明中国碳汇渔业发展态势趋好。③ 碳汇能力影响因素中,价值效应大于规模效应和结构效应,渔业相关的法律、法规对规模效应和结构效应的影响显著。研究海水养殖碳汇有利于促进海洋渔业高质量发展,以期为开发利用海洋渔业碳汇提供理论依据。  相似文献   

东太平洋海隆13°N和赤道附近表层沉积物中的元素赋存状态     

李康  曾志刚  殷学博  陈帅  王晓媛  张国良  陈代庚  汪小妹 《海洋地质与第四纪地质》2009,(3)

为了解海底热液活动对沉积物元素赋存状态的影响,对东太平洋海隆(EPR)13°N和赤道附近表层沉积物样品17A-EPR-TVG1、17A-EPR-TVG5做了全样及顺序提取分析,探讨了Al、Ca、Fe、Mn、Ti、Ba、Zn、Cu、Sr、V、Mo、U及稀土元素赋存状态。XRD结果显示,17A-EPR-TVG1沉积物的主要矿物形态为黄铁矿,17A-EPR-TVG5沉积物样品主要矿物为方解石。受热液影响明显的17A-EPR-TVG1沉积物中,除Ca、Sr外,其余元素主要赋存于铁锰氧化物与残留相中。正常深海沉积物17A-EPR-TVG5中,除Al、Ba、Ti外,其余元素主要赋存于碳酸盐相及铁锰氧化物相中。稀土元素的顺序提取结果显示,17A-EPR-TVG1沉积物4个相态稀土元素北美页岩配分曲线中均有Eu正异常,17A-EPR-TVG5沉积物4个相态稀土元素北美页岩配分曲线中均出现Ce负异常,分别指示了二者形成过程中热液与海水的加入。  相似文献   

韩国东海Ulleung盆地天然气水合物地震识别标志     

Dong-Hyo Kang  杨传胜 《海洋地质前沿》2009,25(2):21-21

2005年KIGAM利用1035in。的气枪和240道电缆在Ulleung盆地采集了共6600mile的二维地震数据。Ulleung盆地中央深2100m，包含有重力流成因（褶滑断层／滑塌构造、碎屑流和浊积岩）的晚第三纪和第四纪的大部分沉积物。通过分析地震剖面，可以识别BSR、声波空白带、柱状构造、气苗、增强反射。  相似文献   

潮汐调和常数的变化趋势研究          下载免费PDF全文

李改肖  孙新轩  刘雁春  沈康 《海洋测绘》2010,30(3):62-64

潮汐调和常数具有随时间变化的特性,以某一长期验潮站44年的观测数据为样本,研究分析了在短期、中期和长期观测时段下潮汐调和常数的变化规律,计算出各分潮调和常数的平均值、最大互差及中误差的变化量级。研究表明,较短时间的观测资料得出的各分潮调和常数存在着较大的变动误差,但随着观测时间的增长,其误差量级呈逐渐减小并且逐步稳定的变化趋势。建议采用调和常数计算理论最低潮面时,宜选定19年作为观测周期,以消除分潮调和常数的误差影响,满足高精度海洋测深基准面的稳定和统一。  相似文献   

悬跨海底管道疲劳寿命分析研究     

徐进  石兆东  张康 《海洋地质译丛》2009,(3):80-84

海底管道在服役期间由于各种原因会在某些管段形成悬跨。这些悬跨在海流力作用下，将产生涡激振动。这种涡激振动最终可能导致管道疲劳失效。管道在海流力作用下发生的涡激振动是管道振动和漩涡尾流振动耦合的结果。在建立管道振动模型和Matteoluca尾流振子模型基础上，对管道涡激振动动力响应特性进行分析。依据Miner线性损伤累积理论，采用S—N曲线法分析计算管道疲劳寿命。最后，针对海洋油气开发与生产，提出延长海底管道疲劳寿命的方法和措施。  相似文献