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471.
Takushi Niki Miwa Shimizu Ayako Fujishiro Junji Kinoshita 《Journal of Oceanography》2007,63(5):873-877
During time-series observations in Sagami Bay, Japan, the concentration of dissolved dimethylsulfoniopropionate (DMSPd), a precursor of dimethylsulfide (DMS), was negatively correlated with salinity. In the laboratory, low-salinity shock reduced
DMS production rates of the natural bacterial community and induced rapid DMSP release from a dinophyte, Heterocapsa triquetra, suggesting that low-salinity shock reduced DMSPd consumption but enhanced DMSPd production, which agrees with the negative correlation between DMSPd and salinity observed in Sagami bay. In addition, low-salinity shock did not affect DMSP lyase activity of H. triquetra. Low-salinity shock would increase the contribution from algae in DMS production, leading to an increase in potential DMS
productivity in the environment. 相似文献
472.
长江口及济州岛附近海域变性水团的初步分析 总被引:1,自引:0,他引:1
基于变性水团的概念,本文把聚类分析用于确定长江口及济州岛附近海域变性水团的边界。由聚类分析得到的结果表明,在该海区有十个水团。对它们的特征、分布与变化进行了初步分析。作者得出的结论是:1、在十个水团中,有四个大洋性水团,六个变性水团。2、该海域水团变性的特点为暧季增温、降盐、降氧,而冷季则相反。3、水团变性是由海区内、外因素综合作用而发生的,而后者在浅水区域起主要作用。4、水团边界的舌状分布与流向之间有明显关系。因之,海流的方向及强度,大致可依水团舌状分布而判断。5、底层中心渔场基本上位于各变性水团之间的混合区或其附近。 相似文献
473.
利用TM合成图像研究滨海平原城市东营市的时空扩展 总被引:1,自引:0,他引:1
利用遥感 (RS)与地理信息系统 (GIS)一体化技术 ,对黄河三角洲上的新兴城市——东营市的城市时空扩展进行动态监测。并在地物光谱研究的基础上 ,提出了适合于近海平原地区的遥感波段组合 (TM- R5 G3B1)和本区内最易于识别城镇、居民地的波段组合 TM- R5 G7B4 (7月 )、TM-R3G4 B2 (10月 )和 TM- R5 G2 B4 (5月 )。结果表明 ,东营市自 1983年建市以来 ,迅速向东发展 ,由一块城区扩展为东城、西城并立。国家的政策和规划、石油工业的发展是东营城区迅速扩展的驱动力。 相似文献
474.
高精度CTD剖面仪电导率传感器的研究和实验 总被引:3,自引:2,他引:3
高精度CTD剖面仪是海洋863项目的重要组成部分,是海洋调查和水文观测必不可少的仪器,本文详细论述了CTD剖面仪中电导率传感器的研制方法和过程,并给出传感器现已达到的水平,提出还需要进一步进行的工作和深入研究的问题。 相似文献
475.
Algorithm for HF radar vector current measurements 总被引:1,自引:0,他引:1
A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured
by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic
assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution
of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages
over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based
on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the
total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation.
The new algorithm is applied to the field experiment data of Wuhan University’s ocean state measuring and analyzing radar
(OSMAR), collected in the coastal East China Sea during April 11–17, 2004. Quantitative comparisons are given between radar
results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements. 相似文献
476.
The Blake Outer Ridge is a 480–kilometer long linear sedimentary drift ridge striking perpendicular to the North American
coastline. By modeling free-air gravity anomalies we tested for the presence of a crustal feature that may control the location
and orientation of the Blake Outer Ridge. Most of our crustal density models that match observed gravity anomalies require
an increase in oceanic crustal thickness of 1–3 km on the southwest side of the Blake Outer Ridge relative to the northeast
side. Most of these models also require 1–4 km of crustal thinning in zone 20–30 km southwest of the crest of the Blake Outer
Ridge. Although these features are consistent with the structure of oceanic fracture zones, the Blake Outer Ridge is not parallel
to adjacent known fracture zones. Magnetic anomalies suggest that the ocean crust beneath this feature formed during a period
of mid-ocean ridge reorganization, and that the Blake Outer Ridge may be built upon the bathymetric expression of an oblique
extensional feature associated with ridge propagation. It is likely that the orientation of this trough acted as a catalyst
for sediment deposition with the start of the Western Boundary Undercurrent in the mid-Oligocene. 相似文献
477.
副渔获物对渔业资源的影响及其减少方法的探讨 总被引:1,自引:0,他引:1
由于渔具不同的选择性和多鱼种鱼类共栖 ,人们在对目标种类进行捕捞时 ,不可避免地产生副渔获物及其抛弃。由于渔业资源的下降和人们对海洋环境保护意识的加强 ,副渔获物及其抛弃问题日益成为人们关注的焦点。本文对世界范围内的渔业活动所产生的副渔获物进行分析 ,根据副渔获物的种类、被抛弃情况和原因以及对渔业资源的影响 ,提出了减少副渔获物和抛弃的方法。 相似文献
478.
Shinya Magome Tomohiro Yamashita Takeshi Kohama Atsushi Kaneda Yuichi Hayami Satoru Takahashi Hidetaka Takeoka 《Journal of Oceanography》2007,63(5):761-773
Jellyfish patch formation is investigated by conducting a drifter experiment combined with aerial photography of a sustained
patch of the moon jellyfish in Hokezu Bay, Japan. Jellyfish patches are aggregations of individuals that are caused by a combination
of swimming (active influence) and advection by currents (passive influence). The drifter experiment involved the injection
of 49 drifters around a distinct surface patch of jellyfish within an area of approximately 300 m × 300 m. The drifters’ motion,
caused only by the passive influence, was recorded in a series of 38 aerial photographs taken over approximately 1 h. The
ambient uniform current field larger than the patch scale was estimated from the movement of the centroid position of drifters,
while the distribution of horizontal divergence and relative vorticity around the patch was estimated from the time-derivative
in areas of triangles formed by the drifters. The centroid positions of both drifters and patches moved stably toward the
bay head at different speeds. The difference vector between the patch and drifter centroids was directed to the sun, and was
opposite to the ambient current. The distributions of vorticity and divergence around patches exhibited inhomogeneity within
the patch scale, and the drifters in this nonuniform current field aggregated near the convergence area within 1 h. The results
suggest that horizontal patch formation is predominantly influenced by passive factors at the surface of Hokezu Bay. Furthermore,
the upward swimming against downwelling may make sustained patch in surface layer. 相似文献
479.
The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated
before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal
transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following
the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant
taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from 1156 inds/10
cm2 to 2082 inds/10 cm2. The increase in densities from the mangrove forest edge towards the low water line was significant. Along the mudflat transect,
the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly
along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the
highest abundance 33.8 % were found.Theristus andNeochromadora decreased in densities from the lower water line towards the mangrove forest edge, whileParacomesoma andHopperia are typical and more abundant at the middle of the mudflat.Halalaimus increased from high on the mudflat to the low water line. 相似文献
480.
黑潮延伸区的海平面异常和中尺度涡的统计分析 总被引:4,自引:0,他引:4
利用1993~2004年卫星高度计TP/Jason-1和 ERS/ENVISAT提供的海平面异常(SLA)融合数据,分析了黑潮延伸区12年来的平均海平面异常的变化特征及中尺度涡的分布规律.研究表明,在黑潮延伸区海平面异常(SLA)呈递增趋势,年平均上升率为8.89mm/a,显著性周期是1年、0.5年和6年;黑潮延伸区的海平面异常和海表面温度异常的低频分量与Nino3指数具有较高的相关性.这说明,黑潮延伸区的海平面变化和海表面温度与厄尔尼诺事件密切相关,都受到黑潮变化的密切影响.在日本东部的黑潮延伸区,中尺度涡自东向西移动,寿命约为1年,移动速度大约是10经度/年.气旋涡和反气旋涡的面积呈现几乎同步增减的规律,均呈年周期变化,上半年少,下半年多.在1997~1998年,黑潮延伸区内中尺度涡的面积显著减小,并且正好对应于Nino3指数极大值出现的年份.因此,黑潮延伸区内中尺度涡的数量和强度也与厄尔尼诺事件密切相关. 相似文献