A model of the upper branch of the meridional overturning of the southern ocean

A zonal-average model of the upper branch of the meridional overturning circulation of the southern ocean is constructed and used to discuss the processes – wind, buoyancy, eddy forcing and boundary conditions – that control its strength and sense of circulation. The geometry of the thermocline ‘wedge’, set by the mapping between the vertical spacing of buoyancy surfaces (the stratification) on the equatorial flank of the Antarctic Circumpolar Current and their outcrop at the sea surface, is seen to play a central role by setting the interior large-scale potential vorticity distribution. It is shown that the action of eddies mixing this potential vorticity field induces a residual flow in the meridional plane much as is observed, with upwelling of fluid around Antarctica, northward surface flow and subduction to form intermediate water. Along with this overturning circulation there is a concomitant air-sea buoyancy flux directed in to the ocean.     

Least-Squares Estimation of Bottom Topography Using Horizontal Velocity Measurements in the Tsushima/Korea Straits

Several bathymetric data sets are compared and assessed with constraints of an ocean current model and velocity observations. The root-mean-square (rms) differences among the data sets reach 20 m in the shallow Tsushima/Korea Straits. The numerical experiments to simulate the Tsushima Warm Current are performed using four different topography data sets. The JTOPO1 data (MIRC, 2003) give the smallest rms difference to long-term horizontal velocity observations. Several least-squares combinations of the topography data sets are then sought to minimize the rms difference between the observed and modeled barotropic velocities. Most of the data sets reveal a large bias of 30–60 m at the Western Channel compared to independent sounding depths     

渤海海流概况及其输沙作用初析

本文讨论了渤海及黄河口附近海域的海洋动力状况，潮流和风暴急流是输送黄河入海泥沙的主要动力。     

冬季黄海暖流的诊断计算

采用ECOMSED三维水动力模式，诊断计算了冬季渤海、黄海和东海的近海环流状况，重点分析了黄海暖流的演变过程及其垂直结构，并探讨了黄海暖流的形成机理。结果表明，黄海暖流于12月初步形成，次年2月发展最强盛，3月开始衰退。黄海暖流在表层和次表层（0-30m）并不是一支持续稳定的流，其持续稳定性仅在近底层得到很好的体现。对黄海暖流形成机理的分析表明，压强梯度力、垂向摩擦力和柯氏力占主要地位。在表层及次表层，主要表现为风的正压作用，而在近底层，则由海平面起伏造成的正压梯度力和密度场引起的斜压梯度力形成的总压强梯度力与柯氏力基本平衡，因而黄海暖流可基本认为是准地转流。     

Zoogeography of marine Bryozoa around South Africa

The zoogeography of marine Bryozoa around South Africa was investigated using published distribution records, museum catalogues, and an examination of previously unworked bryozoan material in (mostly) museum collections. Although a total of 276 valid species are recognised, it was not possible to unambiguously assess geographic patterns of diversity. At all depth zones examined (shore and inner-shelf, 0–30 m; mid- and outer-shelf, 31–350 m; bathyal, >500 m), there was a clear geographic structure to communities that mirrored established regional patterns of biogeography. Too few samples were collected from the shelf edge (351–500 m) and they were consequently excluded from zoogeographic analysis. Communities on the shore and inner-shelf and on the mid- and outer-shelf were more similar to each other than they were to bathyal communities, and the pronounced structure in bathyal communities suggests heterogeneity in the deep sea around South Africa.     

西北太平洋副热带逆流、北赤道流、北赤道逆流几个特征的比较

根据137°E断面1967～1995年冬、夏季的温、盐资料,计算和分析该断面的地转流;分析144°E断面上投放卫星跟踪漂流浮标的漂移轨迹;结合CSK图集中的海面重力势分布,对副热带逆流、北赤道流和北赤道逆流几个特征的相同点和不同点进行比较,得出若干有益的结论:(1)副热带逆流、北赤道流、北赤道逆流,并不是单纯的单支海流,而是存在着两支或多支现象;(2)流速结构的带状分布,东、西向流相互交错间隔出现,流层较浅,均为表层流或近表层流;(3)多年平均而言,3支海流的流速以北赤道逆流最强,北赤道流次之,副热带逆流最弱;流量则不同,北赤道流最大,副热带逆流最小,北赤道逆流居中.3支海流的流速夏季均大于冬季,但流量稍有差异:副热带逆流和北赤道流均具有夏强、冬弱的特点,而北赤道逆流为冬强、夏弱;(4)冬季,副热带逆流的"源地",位于巴士海峡和台湾以东"副热带脊"的一个"暖脊"中心附近海域;(5)冬季,卫星跟踪漂流浮标的漂移轨迹,基本上反映出北赤道流和北赤道逆流的路径.但因副热带逆流区为涡旋频繁区,致使浮标漂移轨迹难以反映出副热带逆流的路径.     

The circulation in the southern Huanghai Sea and northern East China Sea in June 1999

On the basis of hydrographic data and current measurement (the mooring system, vessel-mounted ADCP and toward ADCP) data obtained in June 1999, the circulations in the southern Huang-hai Sea (HS) and northern East China Sea (ECS) are computed by using the modified inverse method. The Kuroshio flows northeastward through eastern part of the investigated region and has the main core at Section PN, a northward flow at the easternmost part of Section PN, a weaker anti-cyclonic eddy between these two northward flows, and a weak cyclonic eddy at the western part of Section PN. The above current structure is one type of the current structures at Section PN in ECS. The net northward volume transport (VT) of the Kuroshio and the offshore branch of Taiwan Warm Current (TWCOB) through Section PN is about 26.2×106m3/s in June 1999. The VT of the inshore branch of Taiwan Warm Current (TWCIB) through the investigated region is about 0.4×106m3/s. The Taiwan Warm Current (TWC) has much effect on the currents over the     

Considering ecosystem-based fisheries management in the California Current

Recognizing that all management decisions have impacts on the ecosystem being exploited, an ecosystem-based approach to management seeks to better inform these decisions with knowledge of ecosystem structure, processes and functions. For marine fisheries in the California Current, along the West Coast of North America, such an approach must take into greater consideration the constantly changing climate-driven physical and biological interactions in the ecosystem, the trophic relationships between fished and unfished elements of the food web, the adaptation potential of life history diversity, and the role of humans as both predators and competitors. This paper reviews fisheries-based ecosystem tools, insights, and management concepts, and presents a transitional means of implementing an ecosystem-based approach to managing US fisheries in the California Current based on current scientific knowledge and interpretation of existing law.     

Spatial variability of phytoplankton absorption coefficients and pigments off Baja California during November 2002

We have estimated the spatial variability of phytoplankton specific absorption coefficients (a* _ph ) in the water column of the California Current System during November 2002, taking into account the variability in pigment composition and phytoplankton community structure and size. Oligotrophic conditions (surface Chl < 0.2 mg m⁻³) dominated offshore, while mesotrophic conditions (surface Chl 0.2 to 2.0 mg m⁻³) where found inshore. The specific absorption coefficient at 440 [a* _ph (440)] ranged from 0.025–0.281 m²mg⁻¹ while at 675 nm [a* _ph (675)] it varied between 0.014 and 0.087 m²mg⁻¹. The implementation of a size index based on HPLC data showed the community structure was dominated by picoplankton. This would reduce the package effect in the variability of a* _ph (675). Normalized a _ph curves were classified in two groups according to their shape, separating all spectra with peaks between 440 and 550 nm as the second group. Most samples in the first group were from surface layers, while the second group were from the deep chlorophyll maximum or deeper. Accessory photoprotective pigments (APP) tended to decrease with depth and accessory photosynthetic pigments (APS) to increase, indicating the importance of photoprotective mechanisms in surface layers and adaptation to low light at depth. Samples with higher ratios of APP:APS (>0.4) were considered as phytoplankton adapted to high irradiances, and lower ratios (<0.26) as adapted to low irradiances. We found a good relationship between APP:APS and a* _ph (440) for the deeper layer (DCM and below), but no clear evidence of the factors causing the variability of a* _ph (440) in the upper layer.     

Tintinnids (Ciliophora) and Other Net Microzooplankton (> 30 µm) in Southwestern Atlantic Shelf Break Waters

Abstract. Proportions of foraminifers, tintinnids, polycystine radiolarians, pteropods and crustacean larval stages were estimated in a collection of 76 vertically stratified (0 – 100 m) 30 µm net microplankton samples from 16 stations along the Argentine shelf-slope (around 200 m isobath – between 40 and 56° S), covered on 13 – 18 November 1996. Tintinnids were identified to species. Relative abundances of the microzooplankton assessed and chlorophyll a values allow to define two contrasting groups of stations: 'deep' and 'shallow'. The former, located in pelagic, purely subantarctic Malvinas Current waters, hosted higher proportions of foraminifers and lower proportions of tintinnids, as well as less chlorophyll a (all differences were significant at the 0.1 % level). 'Shallow' stations were located in the area of the thermohaline front where the Patagonian Current comes in contact with the Malvinas Current, and were generally characterized by higher chlorophyll a levels (up to 3.7 µg Chl a  · l^–1). The distribution of tintinnid species, on the other hand, allowed no discrimination between these two areas, although some of the dominant forms showed much higher relative abundances in one of the two groups of stations. Twenty-six tintinnid taxa were recorded, yet only 6 accounted for 95 % of the specimens identified. Tintinnid taxocoenoses were characterized by a few abundant species and many rare ones. Numbers of tintinnid species and specific diversity did not differ noticeably with depth and latitude. Cape Horn Current waters were detected in the area by the presence of expatriated organisms presumably originating at mid-latitudes in the South Pacific Ocean.