西太平洋暖池区热带波动的天气效应     

常美桂  王衍明 《海洋与湖沼》1995,26(S1):40-46

为了探讨西太平洋暧地区热带波动的天气效应，利用1980年2－9月140°E日本静止卫星纬度时间剖面卫星云图，分析了5d和14d左右周期热带波动云的演变特征，井综合分析了14d周期的云系演变型式与流场的关系，为预报热带中期天气变化规律提供了依据；热带波动中30－60d大气低频振荡的云量变化最显著，北半球夏半年热带波动的天气压主要在10°N－0°，各半年在10°N－10°S，超过这个区域热带云量的港分布型式就有明显的变化。  相似文献   

Experimental study of the breaking limit of multi-directional random waves passing over an impermeable submerged breakwater     

D. -S. Hur  N. Kawashima  K. Iwata 《Ocean Engineering》2003,30(15):1923-1940

This study investigates experimentally the breaking wave height of multi-directional random waves passing over an impermeable submerged breakwater. Experiments have been conducted in a three-dimensional wave basin equipped with a multi-directional random wave generator. A special type of wave gauge has been newly devised to record the water surface elevations in the breaker zone as accurately as possible. The records are analyzed to estimate the location and limit of wave breaking. Comparisons have also been made with the results of regular waves. The influence of the incident wave conditions on the breaking wave height normalized by the breakwater dimensions has been investigated. Empirical formulae have been presented to estimate the breaking limit of multi-directional random waves based on the experimental records. The formulae have been tested and found to work well not only for multi-directional random waves, but for regular waves as well.  相似文献   

Regression Formulations for the Stress at Hot Spot of Multiplanar Tubular DT Joints     

Chen Tieyun Zhang Huiyuan Professor  Shanghai Jiao Tong University  Shanghai Doctor of Engineering  Shenzhen Shipbuilding Trading Co. LTD. 《中国海洋工程》1993,(1)

- Stress concentration analysis of multiplanar tubular DT joints plays an important role in the fatigue design of offshore platforms. A semi-analytic method for stress analysis under the condition of any loads is briefly introduced in the paper. Nineteen multiplanar tubular DT joints with one of two braces of the same dimension subjected to axial loads and out- of- plane bending moments are computed for parametric stress analysis by using the present method. The influence of geometrical parameters on the stresses of multiplanar tubular DT joints is discussed and compared with corresponding uniplanar T joints. The regression formulae for the stress at hot spot of multiplanar DT joints are found by modification of SCF of corresponding uniplanar T joints. The parametric formulae for the maximum stress by superposition. Finally, the influences of stiffening effect and load-interaction effect on the maximum stress of DT joints are discussed.  相似文献   

龙须菜和扁江篱多糖的组成及其抗肿瘤效果   总被引：22，自引：0，他引：22  

邓志峰  纪明侯 《海洋与湖沼》1995,26(6):575-581

于１９８５－１９８７年期间用冷水和热水对采集于青岛的龙须菜和扁江篱的琼胶型多糖进行提取。两海藻的热水提取多糖都通过ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ５０色谱桩用热水和不同浓度ＮａＣｌ深液前后进行洗脱分级。龙须菜和扁江篱多糖的主要级分分别为０．５ｍｏｌ／Ｌ和１．０ｍｏｌ／ＬＮａＣｌ洗脱级分。对各级分做化学分析及ＩＲ和＾１３ＣＮＭＲ光谱分析。结果表明，龙须菜多糖由琼二糖、琼胶糖前体和６－ＯＣＨ３－琼二糖组成  相似文献   

Optical water type discrimination and tuning remote sensing band-ratio algorithms: Application to retrieval of chlorophyll and K_d(490) in the Irish and Celtic Seas     

David McKee  Alex Cunningham  Agnes Dudek 《Estuarine, Coastal and Shelf Science》2007,73(3-4):827-834

This paper assesses the feasibility of applying remote sensing algorithms based on blue/green reflectance ratios to Case 2 waters. Two algorithms from the SeaDAS (NASA) image processing package, OC4v4 for surface chlorophyll concentration, Chl, and K(490) for the attenuation coefficient for downward irradiance at 490 nm, K_d(490), were investigated using an extensive set of observations from the Irish and Celtic Seas. In situ data from a profiling radiometer were used as inputs for the algorithms to avoid uncertainties in atmospheric correction procedures, and direct measurements of Chl and K_d490 and were used for validation purposes. The standard versions of the algorithms performed poorly: OC4v4 generally overestimated Chl (with a very low coefficient of determination), and K(490) progressively underestimated K_d490 for values greater than 0.3 m⁻¹. A two-step procedure for level 2 product generation was therefore devised in which the numerical coefficients of OC4v4 and K(490) were tuned for the two optical water types known to occur most frequently in this region (McKee, D., Cunningham, A., 2006. Identification and characterisation of two optical water types in the Irish Sea from in situ inherent optical properties and seawater constituents. Estuarine, Coastal and Shelf Science 68, 305–316) by statistical regression on a data set of 102 stations from the Irish and Celtic Seas. The water types were distinguished by the magnitude of their normalised water leaving radiance signals at 665 nm, nL_w(665), and appropriate versions of the tuned algorithms applied to each water type. When this procedure was tested on an independent data set of 19 stations from the Bristol Channel, Chl values were recovered with an RMS error of 0.36 mg m⁻³ and K_d(490) values with an RMS error of 0.095 m⁻¹. The identification of water types from water-leaving radiance signals, and the application of band-ratio algorithms tuned for specific water types, may therefore provide a simple means of improving the quality of remote sensing products in optically complex shelf seas.  相似文献   

台湾海峡1997年8月至1999年8月份海水光学衰减系数的分布特征   总被引：2，自引：0，他引：2  

张彩云  商少平  胡建宇  陈照章 《台湾海峡》2001,20(1):127-131

利用1997－1999年间8月份台湾海峡的实测资料，分析了海水光学衰减系数的垂直分布类型、水平分布特征。结果表明，台湾海峡海水光学衰减系数的垂直分布类型主要分为5种，大部分随深度而递增；光学衰减系数等值线基本与岸线平行，水平梯度自北向南、自近岸向外海递减，近岸等值线密集，而外海稀疏；影响台湾海峡光学衰减系数的主要因素是县浮物质（主要含浮游生物）和海流运动。  相似文献   

Topographic Effect of Izu Ridge on the Distribution of the North Pacific Intermediate Water South of Japan     

Yoshihiko Sekine  Shingo Watanabe  Fukuji Yamada 《Journal of Oceanography》2000,56(4):429-438

The topographic effect of the Izu Ridge on the horizontal distribution of the North Pacific Intermediate Water (NPIW) south of Japan has been studied using observational data obtained by the Seisui-Maru of Mie University (Mie Univ. data) and those compiled by Japan Oceanographic Data Center (JODC data). Both data sets show that water of salinity less than 34.1 psu on potential density () surface of 26.8 is confined to the eastern side of the Izu Ridge, while water of salinity less than 34.2 psu is confined to the southern area over the Izu Ridge at a depth greater than 2000 m and to the southeastern area in the Shikoku Basin. It is also shown by T-S analysis of Mie Univ. data over the Izu Ridge that water of salinity less than 34.2 psu dominates south of 30°N, where the depth of the Izu Ridge is deeper than 2000 m and NPIW can intrude westward over the Izu Ridge. JODC data reveal that relatively large standard deviations of the salinity on surface of 26.7, 26.8 and 26.9 are detected along the mean current path of the Kuroshio and the Kuroshio Extension. Almost all of the standard deviations are less than 0.05 psu in other area with the NPIW, which shows that the time variation in the salinity can be neglected. This observational evidence shows that the topographic effect of the Izu Ridge on the horizontal distribution of the NPIW, which is formed east of 145°E by the mixing of the Kuroshio water and the Oyashio water, is prominent north of 30°N with a depth shallower than 2000 m.  相似文献   

郯庐断裂带的断裂活动对渤海东部中、新生代裂谷盆地发育的控制作用     

李桂群  李学伦 《中国海洋大学学报(自然科学版)》1988,(4)

郯庐断裂带自南而北穿越渤海东部,自中生代中期至新生代中期表现裂谷发育特征。裂谷发育经历两个旋回,各旋回的裂谷发育演化、盆地分布格局,沉积相带,沉积补偿速度等均受断裂带的断裂活动的强烈控制。  相似文献   

Nutrient attenuation in a shallow,gravel-bed river. II. Spatial and temporal changes in nitrogen dynamics and community metabolism     

J. Christopher Rutherford  Roger G. Young  John M. Quinn  Robert J. Wilcock 《新西兰海洋与淡水研究杂志》2020,54(3):410-430

ABSTRACT

Instream processes alter the concentration and bioavailability of nutrients as they are transported downstream. By relating primary production and periphyton composition to changes in nutrient concentration in a gravel-bed river this study made inferences about recycling and attenuation. Where dissolved inorganic nitrogen (DIN) was abundant, concentrations decreased linearly with distance but by less than required to meet the nitrogen demand of primary production. Where DIN was barely measurable photosynthesis was reduced but only by 50%. We infer that recycling sustained primary production even when DIN concentrations were negligibly small. One implication is that DIN removal underestimates attenuation. Further experimental research on recycling and improved modelling is required to better quantify the length of streams adversely affected by nutrients.  相似文献   

海底沉积物颗粒因素在不同频率下对声衰减的影响     

刘强  卢博  黄韶健  张福生 《热带海洋学报》2007,26(4):27-31

综合了多个沉积物声学测量的实验方案,提出适合研究柱状海底沉积物声衰减的实验方案。对黏土质粉砂的物理性质和声学性质作了相关处理,得到了在高、低两种测量频率下该类型沉积物的波形特性、频谱特性和与沉积颗粒因素有关的孔隙度对声衰减比的影响。进一步作了相应的回归分析,低频时方差为0.169—0.175,高频时方差为0.029—0.032,尝试总结出黏土质粉砂类型沉积物在两种频率下的声衰减趋势。  相似文献