An Experimental Study of Several Special Issues Regarding the Ice Force on Conical Structures

The effect of the cone spacing of a conieal structure on the ice force is studied by model experiments. The ice force reduction coefficient presented in this paper expresses the relationship between the ice force and the arrangement of cones. The experiments prove that the mode of the ice failure before the boundary of upward-downward bending cone (UDBC) is crushing. A conclusion can also be drawn from the experiments that the ice force on the boundary of UDBC is by far less than that on a vertical pile with the same diameter. Moreover, the ice force frequencies on upright and inve-rted cones are obtained under the field condition of the platform JZ20-2, respectively. The results show that the alterna-tion of the ice force on UDBC can hardly induce resonance of platform JZ20-2.     

Barotropic Response of the Sea of Okhotsk to Wind Forcing

We have examined wind-induced circulation in the Sea of Okhotsk using a barotropic model that contains realistic topography with a resolution of 9.25 km. The monthly wind stress field calculated from daily European Centre for Medium-Range Weather Forecasting (ECMWF) Re-Analysis data is used as the forcing, and the integration is carried out for 20 days until the circulation attains an almost steady state. In the case of November (a representative for the winter season from October to March), southward currents of velocity 0.1–0.3 m s⁻¹ occur along the bottom contours off the east of Sakhalin Island. The currents are mostly confined to the shelf (shallower than 200 m) and extend as far south as the Hokkaido coast. In the July case (a representative for the summer season from April to September), significant currents do not occur, even in the shallow shelves. The simulated southward current over the east Sakhalin shelf appears to correspond to the near-shore branch of the East Sakhalin Current (ESC), which was observed with the surface drifters. These seasonal variations simulated in our experiments are consistent with the observations of the ESC. Dynamically, the simulated ESC is interpreted as the arrested topographic wave (ATW), which is the coastally trapped flow driven by steady alongshore wind stress. The volume transport of the simulated ESC over the shelf reaches about 1.0 Sv (1 Sv = 10⁶ m³s⁻¹) in the winter season, which is determined by the integrated onshore Ekman transport in the direction from which shelf waves propagate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Model Test Study of Dynamic Ice Force on Compliant Conical Structures

To study ice-induced vibration of a compliant conical structure,a series of model tests were performed from 2004 to 2005.In the tests,the ice sheet before the compliant conical structure was found to fail in two-time breaking.From 2005 to 2006,this type of ice failure was studied through more groups of tests.The tests show that two-time breaking is the typical failure of ice before steep conical structures,and is controlled by other factors at the same time,such as ice speed and the angle of the cone.     

东海浮游翼足类(Pteropods)数量分布的研究

根据1997～2000年东海海域23°30'～33°00'N,118°30'～128°00'E的4个季节海洋调查资料,运用定量、定性方法,探讨了东海浮游翼足类总丰度的平面分布、季节变化及变化的动力学机制.结果表明,东海翼足类总丰度和出现频率有明显的季节变化,均为秋季最高,夏季次之,春季最低;总丰度在各个季节基本上呈东海南部高于北部、外海高于近海的分布趋势;春季的尖笔帽螺(Creseis acicula)、夏季的锥笔帽螺(Creseis virgula)、秋季的蝴蝶螺(Desmopterus papilio)和冬季的马蹄螔螺(Limacina trochiformis)是导致总丰度季节变化的最主要的种类;冬、春和夏3个季节丰度变化及4季总丰度的变化同表层或10m层水温有非常显著的线性相关关系,与底层温度及盐度的相关关系不显著.夏季翼足类高丰度区位于台湾暖流与黑潮暖流的分支处;从夏季到秋季,翼足类随着台湾暖流向北扩展,并在与长江冲淡水,闽浙沿岸水团,黄海水团等交汇处形成高丰度(大于500×10-2个/m3)和较高丰度(250×10-2～500×10-2个/m3)分布区.水温和海流是影响东海翼足类总丰度分布的主要环境因素.     

热带印度洋偶极子发生和演变机制的数值研究

对中国科学院大气物理研究所(IAP)大气科学和地球流体力学数值模拟国家重点实验室(LASG)发展的第三代海洋模式(L30T63 OGCM)进行了改进。分析了该模式1959年1月—1998年12月的40a积分结果，以此研究热带印度洋偶极子发生、发展和消亡的物理机制。对数值模拟结果的分析表明，赤道印度洋表面异常东风引起的异常环流结构是偶极子发生、发展的主要动力学原因，其表面异常东风转换为异常西风所引起的异常环流结构调整是偶极子消亡的主要动力学原因；海气界面热通量异常的交换对热带印度洋海表温度距平偶极子模态的形成和演变起着重要的作用；垂直输送作用是热带印度洋次表层海温偶极子模态发生和演变的主要物理机制。     

胶州湾围隔浮游生态系统氮、磷营养盐迁移-转化模型研究

通过对目前生态动力学模型的总结和综合,以生态系统中氮、磷营养盐循环为主线,建立了适用于海洋围隔浮游生态系统的多变量的营养盐迁移-转化动力学模型.该模型包括浮游植物、浮游动物、溶解无机态营养盐、溶解有机态营养盐和生物碎屑5个模块,涉及溶解无机氮、磷酸盐、溶解有机氮、溶解有机磷、浮游植物、浮游动物和生物碎屑7个状态变量.分别利用1999年秋季和2000年夏季胶州湾围隔生态实验数据进行了模型和验证工作,成功地模拟了富加营养盐条件下围隔浮游生态系统中氮、磷营养盐生物化学迁移-转化过程,并确定了20余个参数的量值.     

黄河利津水文站不同粒径悬浮颗粒物中有机碳含量的研究

估算不同粒径TSS中POC的入海日通量,对黄河利津水文站悬浮颗粒物(total suspended solid,TSS)样品,采用基于stokes原理的沉降法分为Ⅴ级,对分级后的样品测其有机碳(particulate organic carbon,POC)含量和粒度组成。在此基础上,用多元线性回归法对数据进一步处理,准确得到样品中不同粒径TSS中POC的含量。研究表明,黄河口淡水端水体TSS,<8μm的粘土和极细粉砂、8~16μm的细粉砂中,POC的含量为0.600%和0.400%左右;16~32μm的中粉砂中,POC的含量不足0.200%;而32~63μm的粗粉砂和>63μm砂中POC含量仅为0.050%和0.004%左右,80%以上的POC主要集中在<16μm的TSS中,而<32μm的TSS承载了95%以上的POC。