地形和层结变化对内潮生成影响的数值模拟研究

基于ROMS(Regional Ocean Modeling System)模式,设计了9组理想数值实验,研究了内潮的产生对地形和背景层结环境的敏感性。结果表明:高斯海脊两侧地形梯度较大的超临界坡面处是内潮的主要源区;地形和层结环境的变化对内潮生成有很大影响;如地形和层结保持不变,不同的网格水平分辨率和垂向层数条件下估算的内潮转换率存在差别;地形和跃层的相对空间关系对内潮生成及其引起的水体混合强度存在影响。高分辨率的地形和合适的背景层结是内潮模拟的关键。该结论对于内潮形成的数值模拟研究有一定参考价值。     

Review on Researches of Aragonite Saturation State in the Southern Ocean:A Key Parameter of Southern Ocean Acidification

The Southern Ocean is a strong sink for atmospheric CO₂, making it especially vulnerable to ocean acidification (OA). The aragonite saturation state (Ω_arg) of seawater has been used as an index for the estimation of OA, which plays a critical role in evaluating the living environment of marine calcified organisms. However, it is very difficult to perform the studies of OA and Ω_arg in the Southern Ocean due to its harsh climate. Therefore, in order to better understand the OA and its further influences, the advances of Ω_arg studies were summarized in the oceans surrounding the Antarctica. Significant spatial and temporal variations of surface seawater Ω_arg are demonstrated in the Southern Ocean. In general, the surface seawater Ω_arg shows a lower value in the off-shore areas than in the open oceans. And, Ω_arg also exhibits a strong seasonal cycle with a higher value in summer than in winter. The distributions of Ω_arg in vertical water column generally present a declining tendency from surface to bottom. In addition, the shoaling of Ω_arg horizon at high latitude could be attributed to the ventilation and upwelling of deep waters in the Southern Ocean. There are many factors that could impact the Ω_arg in the Southern Ocean, including sea ice melting, sea-air CO₂ exchange, biological activities and hydrological processes, etc. Finally, the future changes and key scientific problems of OA in the Southern Ocean are proposed.     

Inspirations from IODP Expedition 361

International Ocean Discovery Program, or present IODP that has been evolved from the early Deep Sea Drilling Project (DSDP), Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) is one of the international ocean drilling and exploration programs originated from USA. IODP 361 cruse supported by JOIDES Resolution is characterized of high maneuverability, high tectonic integrity, high comprehensive disciplinary, information aggregation, international researcher gathering, global study targeting, quantity study production, isolated close working environments and huge investment, which is one of the most important international cooperation platforms of the geosciences, especially global changes. It is also one of the super powerful engines not only guiding but also pushing the study on global change via exploring the records of ocean evolution, and also the fountainhead to understand the processes and mechanism of the global changes. As one the main members of the IODP, China is not only participating the activities and scientific researches of IODP, but also needs to improve the capabilities to monitor the ocean and establish our own facilities, laboratories and research centers. These are not only very important for the global research and the future development, but also crucial for the preservation of the ocean environment. Leaning and mastering mature operation models from the JOIDES Resolution, using the experience of IODP management for reference may benefit our research work and yield twice the result with half the effort.     

海洋再分析资料中IOD-ENSO遥相关的海洋通道机制分析

本文利用滞后相关分析,研究了海洋再分析资料（SODA、ORAS4和GODAS）中的IOD-ENSO滞后遥相关关系,并与观测资料进行对比。结果显示,3套再分析资料中热带东南印度洋秋季海表温度/海表高度异常和赤道太平洋冷舌次年秋季海表温度/海表高度异常之间显著相关,与观测结果一致。在次表层,观测和再分析资料均显示,热带东南印度洋秋季海表温度异常与赤道太平洋次表层海温异常之间的显著相关关系在冬季至次年秋季沿赤道太平洋垂向剖面向东移动,并于次年夏季和秋季在冷舌区上升至海表。热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系是由海洋通道机制引起的,即IOD事件引起印尼贯穿流流量异常,导致赤道太平洋温跃层异常,激发赤道Kelvin波向东传播,从而影响赤道中-东太平洋冷舌海表温度异常。观测及SODA与ORAS4资料中,热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系在去除ENSO信号后仍然显著,表明海洋通道机制是独立于ENSO事件的;而在GODAS资料中,这些显著相关关系在去除ENSO信号后消失。印尼贯穿流流量异常和Niño3.4及DMI（Dipole Mode Index）指数之间超前-滞后12个月的相关关系显示,在SODA和ORAS4资料中,印尼贯穿流流量同时受到ENSO和IOD的影响,与观测结果一致;而在GODAS中,印尼贯穿流流量异常仅与Niño3.4指数显著相关,极少受到IOD事件的影响,这部分解释了GODAS资料中去除ENSO信号后,IOD-ENSO滞后遥相关关系消失的原因。     

琉球群岛附近海域中尺度涡的初步研究

采用1977年1月至2006年12月高分辨率全球大洋环流模型OFES输出结果对琉球群岛附近海域的中尺度涡进行了研究分析。结果表明:(1)尺度较大的涡旋的分布密集区主要有台湾以东海域、琉球海沟上层海域和四国以南海域。(2)琉球海流流经海域的反气旋涡旋占优势,有利于琉球海流的发展。(3)琉球海流受中尺度涡的影响十分显著,纬度越低,其受中尺度涡的影响越明显,而黑潮相对比较稳定,受中尺度涡的影响并不显著。(4)四国以南海域暖涡从黑潮脱落之后向西南移动,该涡旋的移动对琉球海流和黑潮产生特别显著的影响。文章的最后还讨论了中尺度涡与黑潮弯曲以及琉球海流可能存在的联系。     

南、北极近岸海水中好氧不产氧光合基因pufM的多样性

好氧不产氧光合(AAP)细菌因其具有利用溶解性有机物及光能的能力,在海洋碳循环及能量流动中发挥着重要的作用。该类细菌广泛分布在海洋环境中,其在不同生境中的多样性已被调查。但到目前为止,人们对于高纬度地区好氧不产氧光合细菌的认识还较为缺乏。有鉴于此,本研究基于编码光反应复合物上一个色素结合蛋白亚基的pufM基因,对北极王湾及南极乔治王岛近岸水体中夏季好氧不产氧光合细菌的多样性进行了检测。针对2个王湾站位和2个南极麦克斯维尔湾站位构建了4个pufM基因克隆文库,获得674个阳性克隆子。北极克隆子全部由α-变形细菌组成,而南极克隆子则包括α-变形细菌及β-变形细菌。来源于类似红细菌科的pufM基因在所有样品中皆占据优势。此外,与一株滴状亚硫酸盐杆菌中质粒编码的pufM基因存在亲缘关系的序列,在南、北极样品中均占优势。结果表明海洋环境中的pufM基因存在跨极甚至是环球分布。与此同时,南、北极序列之间的差异,也表明了极地地方种的存在。这些结果显示,作为好氧不产氧光合细菌的红细菌科在两极的近岸水体中具有重要的地位。     

新疆甜水海地块种羊场石炭纪火山岩年代学和地球化学:岩石成因和地质意义

甜水海地块西段的种羊场地区发育一套互层状产出的玄武岩-玄武安山岩-流纹岩,本文对其进行了岩石学、同位素年代学和地球化学研究。结果表明,流纹岩LA-ICP-MS锆石U-Pb定年获得三组年龄:343.5±4.1Ma表明火山岩的形成时代为早石炭纪,2439±26Ma和1988±36Ma说明甜水海地块存在前寒武纪结晶基底。其中玄武质岩石岩性从拉斑系列、钙碱性系列向碱性系列过渡,呈现出E-MORB(OIB)、大陆板内拉张和岛弧的混合特征,与典型弧后盆地Okinawa玄武岩有一定的差异,表明其可能是异常陆缘弧后盆地拉张裂解的产物。玄武质岩石和流纹岩的主量元素、稀土元素和微量元素比值对的差异表明它们不是同源岩浆演化的产物,玄武质岩石的源区为类似E-MORB(OIB)的岩石圈地幔,且发生了部分熔融,原始岩浆上升过程中经历了矿物分离结晶和地壳混染作用。流纹岩属于高硅高碱的钙碱性火山岩,是上地壳部分熔融的产物。种羊场早石炭纪火山岩可能代表了古特提洋西端早期扩张的记录,为西昆仑-喀喇昆仑地区晚古生代多岛洋格局提供了新的证据。     

Distribution and seasonal abundance of large cetaceans in the Durban whaling grounds off KwaZulu-Natal,South Africa, 1972–1975

Daily charts of the aerial search effort (432 206 nautical miles) of the Union Whaling Company and 1 099 sightings of 10 497 whales were available from 628 flights off Durban between 1972 and 1975. Densities of whales were analysed by month and water depth distribution over the four-year period. Low observed densities of blue Balaenoptera musculus, right Eubalaena australis, sei B. borealis and humpback Megaptera novaeangliae whales most likely resulted from earlier whaling pressure. Seasonality of blue, sei and humpback whales was bimodal, indicative of winter migrations to the north of the Durban whaling grounds, whereas the unimodal seasonality of fin whales B. physalus and minke whales B. bonaerensis or B. acutorostrata suggest the offshore region as the northern terminus of their migrations. Sperm whales Physeter macrocephalus migrate northwards offshore of the KwaZulu-Natal coast in autumn/early winter and southwards in late winter/spring, with larger males migrating later than the smaller males and females. Killer whale Orcinus orca presence was coincident with that of offshore minke whales and the southward migrations of other baleen whales, whereas densities of animals deemed as bottlenose whale Hyperoodon planifrons suggest strong early and late summer seasonal abundance in the offshore region. Such extensive surveys offshore of the KwaZulu-Natal coast are unlikely to be repeated; hence, data-extraction of whaling records provides a valuable source of seasonal and distributional information for marine management.     

The Southwest Indian Ocean thermocline dome in CMIP5 models: Historical simulation and future projection

Using 20 models of the Coupled Model Intercomparison Project Phase 5 (CMIP5), the simulation of the Southwest Indian Ocean (SWIO) thermocline dome is evaluated and its role in shaping the Indian Ocean Basin (IOB) mode following El Niño investigated. In most of the CMIP5 models, due to an easterly wind bias along the equator, the simulated SWIO thermocline is too deep, which could further influence the amplitude of the interannual IOB mode. A model with a shallow (deep) thermocline dome tends to simulate a strong (weak) IOB mode, including key attributes such as the SWIO SST warming, antisymmetric pattern during boreal spring, and second North Indian Ocean warming during boreal summer. Under global warming, the thermocline dome deepens with the easterly wind trend along the equator in most of the models. However, the IOB amplitude does not follow such a change of the SWIO thermocline among the models; rather, it follows future changes in both ENSO forcing and local convection feedback, suggesting a decreasing effect of the deepening SWIO thermocline dome on the change in the IOB mode in the future.     

Static Stability of the Troposphere Over the Southeastern Beaufort Sea–Amundsen Gulf Region of the Western Maritime Arctic

The characterization of the static stability of the troposphere over the western maritime Arctic remains limited in spite of its significance to both atmospheric thermodynamics and dynamics. Field observations of microwave radiometric temperature profiles from the International Polar Year, Circumpolar Flaw Lead System Study (late November 2007 to mid-July 2008) and the ArcticNet field campaign (mid-July to early November 2009) provided a unique opportunity to characterize the static stability of the troposphere over the southeastern Beaufort Sea–Amundsen Gulf region. Notably, the monthly median atmospheric boundary layer (<2000?m) static stability profile for April and the profile for May clearly revealed an inversion elevated above a thermal internal boundary layer, whereas the median summer static stability profiles had very strong surface-based inversions. These profiles have been linked to the seasonal evolution of sea-ice cover in Amundsen Gulf. The monthly static stability profiles for the free atmosphere (2000–10,000?m) revealed an annual cycle. The average static stability of the lower troposphere (2000–5000?m) had a minimum of 3.3?±?0.5?K?km^?1 in July and a maximum of 4.5?±?0.5?K?km^?1 in January and February. In the upper troposphere (>5000–8000?m), the average static stability had a minimum of 2.9?±?0.6?K?km^?1 in June and August and a maximum of 5.3?±?0.8?K?km^?1 in January. The monthly median heights of the tropopause also had an annual cycle. The maximum of 9750?m occurred in June, July, and August. The minimum tropopause height of 8000?m occurred in December, January, and March. The seasonal cycles of static stability in the free atmosphere and the seasonal cycle in the height of the tropopause can be attributed to regional as well as synoptic-scale forcing. This analysis will contribute to the understanding of the thermodynamics and dynamics of a data-sparse region of the Arctic by providing a “snapshot” of the state of the atmosphere through a composite annual cycle.