北大西洋秋季“三极子”海温结构对冬季大气环流场的影响

利用NCEP再分析资料、Hadley中心的海表面温度(SST)资料等,从北大西洋秋季海表面温度异常(SSTA)变化入手,对其影响后期冬季大气环流场的机制进行了分析。研究结果如下:(1)北大西洋SST异常与大气环流异常之间存在着相互作用;(2)秋季北大西洋SSTA具有较好的持续性,"正负正"海温异常空间分布导致12月巴伦支海上空500hPa位势高度异常偏高;(3)异常环流形势对应的海表面风异常场(SSWA)通过阶段性风-蒸发-SST异常反馈机制(WES机制)利于海温异常分布的持续及对上空异常大气环流的反馈;(4)三极子海温结构中负异常海温自10月份开始有自西向东的移动,风作用下蒸发加大,伴随上升运动自欧洲西部爱尔兰群岛出现自西向东移动的降水正异常区,潜热释放有利于冬季巴伦支海上空的异常高压脊发展。研究表明,北大西洋秋季SSTA通过阶段性海气相互作用机制影响海洋温度分布和大气环流异常,对后期冬季中国东北部的气候变化产生影响。     

Factors to consider in evaluating the management and conservation effectiveness of a whale sanctuary to protect and conserve the North Atlantic right whale (Eubalaena glacialis)

This paper examines key factors used in protecting the migratory North Atlantic right whale within the context of a marine protected area (MPA) system, using the Grand Manan Whale Conservation Area, in New Brunswick Canada, as a case study example. Designated as a conservation area in 1993, before the Oceans Act came into effect, the Grand Manan conservation area currently does not form part of the Canadian network of MPAs. Given the possibility that MPA designation may occur, the paper examines factors that should be considered in meeting International Union for Conservation of Nature (IUCN) MPA design criteria and IUCN evaluation model requirements. An MPA evaluation framework based on an IUCN evaluation model (Hockings et al., 2000 [1]) is designed to assess the effectiveness of an MPA in protecting a migratory right whale. Case study results indicate that current management and research activities for the Grand Manan conservation area address most governance, biophysical and socio-economic issues under an IUCN evaluation framework. On a site basis, it is recommended that the Grand Manan conservation area be designated as a component of the Canadian network of MPAs and that regulations be developed and implemented under the Species at Risk Act to clearly define activities considered damaging or destructive to right whale critical habitat. Recommendations also suggest the preparation of a combined site management-action plan for the Grand Manan conservation area indicating how activities specified in North Atlantic Right Whale Recovery Strategy will be implemented locally. On a regional and international basis, recommendations call for an internationally coordinated and integrated approach to right whale protection within the context of a network of designated critical habitat areas. Recommended activities include: continued Canadian participation in cross-border research and actions to mitigate threats to the right whales over their migratory range; development of a regional right whale management and monitoring strategy; and designation of additional critical habitats in national/international waters. It is further recommended that the evaluation framework developed by this paper be used as a model in assessing the conservation and management effectiveness of MPAs protecting other migratory marine species.     

Crustal transect across the North Atlantic

Two dimensional crustal models derived from four different ocean bottom seismographic (OBS) surveys have been compiled into a 1,580 km long transect across the North Atlantic, from the Norwegian Møre coast, across the extinct Aegir Ridge, the continental Jan Mayen Ridge, the presently active Kolbeinsey Ridge north of Iceland, into Scoresby Sund in East Greenland. Backstripping of the transect suggests that the continental break-up at ca. 55 Ma occurred along a west-dipping detachment localized near the western end of a ca. 300 km wide basin thinned to less than 20 km crustal thickness. It is likely that an east-dipping detachment near the present day Liverpool Land Escarpment was active during the late stages of continental rifting. A lower crustal high-velocity layer (7.2–7.4 km/s) interpreted as mafic intrusions/underplating, was present beneath the entire basin. The observations are consistent with the plume hypothesis, involving the Early Tertiary arrival of a mantle plume beneath central Greenland and focused decompression melting beneath the thinnest portions of the lithosphere. The mid-Eocene to Oligocene continental extension in East Greenland is interpreted as fairly symmetric and strongly concentrated in the lower crustal layer. Continental break-up which rifted off the Jan Mayen Ridge, occurred at ca. 25 Ma, when the Aegir Ridge became extinct. The first ca. 2 m.y. of oceanic accretion along the Kolbeinsey Ridge was characterized by thin magmatic crust (ca. 5.5 km), whereas the oceanic crustal formation since ca. 23 Ma documents ca. 8 km thick crust and high magma budget.     

The Common Fisheries Policy: An enforcement problem

Marine populations in Europe are in decline due to the unsuccessful results of the Common Fisheries Policy. By combining data of scientific recommendations from ICES, TACs approved and reported landings with an age-structured model, the objectives of this paper are to investigate the level of compliance of the TAC regulation, and the level of enforcement and its economic impact on fishery resources. The results presented here suggest that while there does not exist a regular pattern between TAC proposal and TAC approved, there is a clear pattern between TAC approved and reported landings. As a consequence, there is a regular lack of enforcement at national fisheries authority level. The paper also presents results of the recovery plans for the Southern hake and the Atlantic cod fisheries as case studies to illustrate the level of enforcement based on collusion between national fisheries advisers and industry. The results from both cases studies analyzed here indicate that drastic solutions could generate positive results for the recovery of the stocks, but perhaps they are not always the best measure in fisheries management due to the high economic losses for fishermen and social effects on coastal communities in the short and medium term. Finally, this work demonstrates that if the recovery plans had been implemented, the net present profits for both fisheries would have increased over time.     

Wintertime rates of net primary production and nitrate and ammonium uptake in the southern Benguela upwelling system

The elevated levels of primary productivity associated with eastern boundary currents are driven by nutrient- rich waters upwelled from depth, such that these regions are typically characterised by high rates of nitrate-fuelled phytoplankton growth. Production studies from the southern Benguela upwelling system (SBUS) tend to be biased towards the summer upwelling season, yet winter data are required to compute annual budgets and understand seasonal variability. Net primary production (NPP) and nitrate and ammonium uptake were measured concurrently at six stations in the SBUS in early winter. While euphotic zone NPP was highest at the stations nearest to the coast and declined with distance from the shore, a greater proportion was potentially exportable from open-ocean surface waters, as indicated by the higher specific nitrate uptake rates and f-ratios (ratio of nitrate uptake to total nitrogen consumption) at the stations located off the continental shelf. Near the coast, phytoplankton growth was predominantly supported by ammonium despite the high ambient nitrate concentrations. Along with ammonium concentrations as high as 3.6 µmol l^–1, this strongly suggests that nitrate uptake in the inshore SBUS, and by extension carbon drawdown, is inhibited by ammonium, at least in winter, although this has also been hypothesised for the summer.     

Trends in the solubility of iron,aluminium, manganese and phosphorus in aerosol collected over the Atlantic Ocean

The solubility of iron, aluminium, manganese and phosphorus has been determined in aerosol samples collected between 49°N and 52°S during three cruises conducted in the Atlantic Ocean as part of the European Union funded IRONAGES programme. Solubilities (defined at pH 4.7) determined for Fe and Al in samples of Saharan dust were significantly lower (medians 1.7% and 3.0%, respectively) than the solubilities of these metals in aerosols from other source regions (whole dataset medians 5.2% and 9.0%, respectively). Mn solubility also varied with aerosol source, but the median solubility of Mn in Saharan dust was very similar to the median for the dataset as a whole (55% and 56%, respectively). The observed solubility of aerosol P was ∼ 32%, with P solubility in Saharan aerosol perhaps as low as 10%. Laboratory studies have indicated that aerosol Fe solubility is enhanced by acid processing. No relationship could be found between Fe solubility and the concentrations of acid species (non-seasalt SO₄²⁻, NO₃⁻) nor the net acidity of the aerosol, so we are unable to confirm that this process is significant in the atmosphere. In terms of the supply of soluble Fe to oceanic ecosystems on a global scale, the observed higher solubility for Fe in non-Saharan aerosols is probably not significant because the Sahara is easily the dominant source of Fe to the Atlantic. On a smaller scale however, higher solubility for aerosol Fe may alter our understanding of Fe cycling in regions such as the remote Southern Ocean.     

Salt tectonics in the Cap Boujdour Area,Aaiun Basin,NW Africa

Seismic reflection data indicate the Moroccan salt basin extends to the Cap Boujdour area in the Aaiun Basin. Two salt diapir structures have been identified and several areas of collapsed strata indicate probable salt removal at the shelf edge. The presence of salt in this area correlates to the conjugate southern George's Bank Basin and the Baltimore Canyon area, and it is suggested that the salt extends southward from the known salt diapir province in the George's Bank Basin southward to the Great Stone Dome. The paucity of salt diapirs is attributed to the thick carbonate and anhydrite sequence, which was deposited soon after salt deposition that inhibited halokinesis. The presence of salt along this large segment of the Atlantic margin should increase its hydrocarbon potential with traps created around salt diapirs and provision of migration pathways from deep potential source rocks in the early Cretaceous and Jurassic strata to shallower levels.