基于非规则网格模型的全球潮流能评估

利用网格有限体积海洋模式,在非规则网格模型中考虑内潮黏性和自吸−负荷潮联合作用,建立了包括M2、S2、N2、K1、O1、Q1共6个分潮的天体引潮力驱动全球纯动力潮汐模型。在全球潮汐模型结果验证的基础上,系统计算和统计评估全球潮流能平均密度,并给出全球范围内潮流能较大区域的潮流能分布。结果显示,英吉利海峡处存在面积接近33 000 $ {{\rm{k}}{\rm{m}}}^{2} $,最大潮流能密度达到1 100 $ {\rm{W}}/{{\rm{m}}}^{2} $的大潮流能带;加拿大巴芬岛西侧海域最大潮流能密度超过了1 150 $ {\rm{W}}/{{\rm{m}}}^{2} $;阿拉斯加沿海库克湾海域最大潮流能密度达到了500 $ {\rm{W}}/{{\rm{m}}}^{2} $;俄罗斯白海入口处潮流能带面积较大,最大潮流能密度达到了500 $ {\rm{W}}/{{\rm{m}}}^{2} $;澳大利亚沿海潮流能带面积不大,但数量众多,潮流能密度普遍超过了100 $ {\rm{W}}/{{\rm{m}}}^{2} $;中国近海在长江口杭州湾海域以及台北以北海域潮流能密度达到了100 $ {\rm{W}}/{{\rm{m}}}^{2} $。     

瞬变电磁法中关断电流的响应计算与校正方法研究

关断电流的存在直接影响仪器的探测能力和数据资料的解释.为了分析和校正这种影响,文中给出了关断时间的计算方法,根据多匝回线源产生的瞬变场理论解析式,计算了线性和半正弦关断电流影响下瞬变场表达式,计算半正弦关断电流产生的瞬变场时将正弦函数进行泰勒展开;分析了关断时间在2μs～100 μs之间两种关断模式产生的瞬变响应.结果显示;同一关断时间下线性关断电流和半正弦关断电流对瞬变场的影响主要表现在"早期",并且随观测时间的增加影响逐渐减弱.同时,关断时间越长,关断效应对瞬变场的影响越向瞬变"晚期"延伸;半正弦关断电流对瞬变场的影响大于线性关断电流.当关断时间为100 μs时,关断电流产生的瞬变场曲线约在0.5 ms之后与理论曲线重合.研究结果为数据处理和仪器开发提供参考.     

曹妃甸某大型工程钻孔灌注桩试桩施工及检测结果分析

曹妃甸某大型工程在工程桩施工前进行试桩,通过对后压浆钻孔灌注桩、三岔双向挤扩桩、支盘灌注桩3种试桩的竖向承载力试验、桩身内力试验、低应变检测、超声波检测及水平承载力试验等项目进行分析,检验成桩的可能性与可靠性,为工程桩桩型的选择及施工提供有效依据。     

关于海洋中的正压流和斜压流问题的讨论

关于海洋中的正压流和斜坛流的概念，目前存在着３种不同的提法．本文首先分别简述它们在定义上的差别，然后对３种定义在理解海流性质问题上的长、短处加以评述。一些理论物理海洋学家依据地转关系式，把与海面倾斜相连系的流视为正压流部分，而与密度不均匀性有关的视为斜压流部分。笔者认为这种定义在物理概念上是清楚，在实际应用中是方便，因此在讨论海流性质时最好采用这种观点。     

定向钻进技术发展与展望

我国定向钻进技术的研究已进入世界先进国家行列。列举了我国在定向钻进器具方面的科研成果及典型的定向钻进应用实例,着重介绍了目前国际上与定向钻进有关的先进技术,并就我国拓宽定向钻进应用新领域及相应需要研究的新技术提出了参考性建议。     

Interaction between a surface jet and subsurface vortices in a three-layer quasi-geostrophic model

This study focuses on the interaction between mid depth vortices and surface jets and fronts in a three-layer quasi-geostrophic model. Such vortices may be regarded as an idealisation of meddies, eddies of Mediterranean Water in the Northeastern Atlantic Ocean, interacting with the Azores j t and front. Successively, a single vortex, a vortex doublet and a vortex pair (in the middle layer) are studied. When a single vortex is considered, the jet has a critical effect of its motion, temporarily slowing down its zonal drift and accelerating it meridionally as the vortex crosses the front. On the contrary, if the vortex does not cross the front, it can drift fairly rapidly along it. The merger of a vortex doublet (two like-signed vortices) below a surface jet is possible whatever the relative position of this doublet with respect to the jet axis. Nevertheless, doublets initially located below the front, will undergo stronger shear and merger efficiency will be diminished. The merged vortex will be circled at the surface by a large meander of the jet. Finally, eastward jet-dipole interaction experiments are performed with various orientations of the vortex dipoles. Eastward propagating dipoles below the jet follow it without deformation. Southeastward drifting dipoles finally join the previous evolution. Southward and southwestward directed dipoles cross the surface jet southeastward. The presence of meanders initially on the jet does not prevent its crossing by a single vortex. Characteristics of the surface jet meanders are also described for a possible remote detection of this process.     

武汉地铁运行对应城地震台地磁观测的影响

利用应城地震台2018—2022年地磁观测数据,研究了武汉地铁对Z分量的影响特征。结果表明,应城地震台地磁Z分量背景噪声约0.13 nT,自2019年2月开始受到武汉地铁影响,干扰时段数据出现微小的高频突变。干扰强度与地铁的距离、牵引电压、走行轨的绝缘性等有关,距离越近、牵引电压越高干扰幅度越大;多条线路造成的干扰可能存在叠加。采用直流750 V牵引电压的地铁在80 km外干扰强度小于0.2 nT,而采用直流1 500 V电压的地铁在相同距离干扰强度大于0.6 nT。     

Temporal variation in phytoplankton composition related to water mass properties in the central part of Sagami Bay

Temporal variations in water mass properties and the composition of phytoplankton pigments in the central part of Sagami Bay were investigated by monthly observations from June 2002 to May 2004. Eleven pigments were quantified using high-performance liquid chromatography (HPLC) from 100%, 20%, and 5% light depths relative to the surface; the class-specific composition of phytoplankton community was then obtained by CHEMTAX analysis. The study area was influenced by the Kuroshio water for most of the observation period. The mean contribution of diatoms in all samples was relatively low (29%), while that of flagellates, mainly chlorophytes or cryptophytes, was quite high (60%). The phytoplankton composition at the three depths was uniform throughout the observation period, indicating that the vertical structure of the phytoplankton community did not develop significantly over time. A distinct temporal pattern was observed: flagellates dominated during the summer of 2002 and the winters of 2002–2003 and 2003–2004, while diatoms dominated during the summer of 2003. This pattern was associated with water mass changes. The community in the summer of 2003 was influenced by coastal water. While no distinct spring bloom of phytoplankton was observed, a weak increase in chlorophyll a was observed during the spring of 2004. Ocean color satellite data showed that fluctuations in chlorophyll a concentrations at time scales much shorter than a month occurred during the spring of 2003 and that the elevations in chlorophyll a levels were not continuous. The fluctuations were probably associated with rapid flushing by the Kuroshio water, which has low chlorophyll a content.     

西北太平洋海域黑潮区有机氯农药和多氯联苯的浓度及其组成特征

由于传统持久性有机污染物（POPs）如有机氯农药（OCPs）和多氯联苯（PCBs）在全球范围内被广泛的限制或禁用,各种环境介质中的污染物浓度呈现逐年降低的趋势。西北太平洋作为远离大陆的开放性海域,无明显的污染点源,其洋流在POPs的输送和扩散过程中扮演重要的角色。本研究采集西北太平洋黑潮区表层和次表层（2～5 m和150 m）水体为研究对象,分析其中溶解态OCPs（六六六（HCHs）、滴滴涕（DDTs）、氯丹（CHLs））和PCBs的浓度及组成特征。结果显示,黑潮区表层水体中HCHs、DDTs、CHLs和PCBs的浓度范围分别为30.7～68.8 pg/L、6.16～23.8 pg/L、1.07～5.75 pg/L和49.8～124 pg/L;次表层水体中分别为27.3～68.4 pg/L、7.06～14.1 pg/L、0.518～10.1 pg/L和34.1～68.4 pg/L。HCHs各异构体的比值特征表明该海域以林丹输入为主,而DDTs和CHLs的比值结果显示,该海域水体中滴滴涕和氯丹均主要是来自于历史残留。水体中PCBs主要以三氯联苯、四氯联苯为主,与东亚多氯联苯的历史使用情况吻合。黑潮水团体量巨大且内部分布均匀,对污染物的垂直分布产生重要影响,即不同深度水体中OCPs、PCBs浓度及其组成相当;同时黑潮带来的高温、高营养盐水团对其海域生物体内污染物的富集形成潜在风险。     

Approximate velocity formula over mobile sediment bed induced by velocity-skewed waves and current

A velocity formula is proposed for flow over a mobile sediment bed induced by velocity-skewed waves and current. The formula is obtained by a separation of waves and current velocities and requires seven free variables related to free stream velocity and sediment characteristics. The formula includes two parts:(1) a wave part consisting of the free stream velocity and defect function, which considers phase lead, wave boundary layer thickness, and mobile bed level, and(2) a current part, which ch...