耦合模式中潮汐对北大西洋模拟的影响研究     

于溢  刘海龙  林鹏飞  兰健 《气候与环境研究》2018,23(3):259-267

将8个主要平衡分潮加入到耦合模式中,对比研究潮汐对北大西洋模拟影响。由于潮汐的引入,模式模拟SST在北大西洋中纬度区域偏差显著减小,高纬度区域SST降温明显。SST模拟的改变使潮汐试验的海表净热通量模拟误差下降了约30%,但高纬度海冰显著增加。模式中引入潮汐对北大西洋上层环流,尤其是西边界流的路径模拟改进显著,这是SST及海表净热通量模拟改变的主要原因。同时,北大西洋上层和深层西边界流在潮汐的作用下,都表现出环流减弱的特点,这也使得大西洋经向翻转环流在26.5°N处上层2 km的输送减弱,与观测数据更为接近。较弱的大西洋经向翻转环流导致海洋热量在中低纬度聚集而无法输送到高纬度区域,这是造成潮汐试验模拟的海温在中低纬度偏高、高纬度偏低的原因,较弱的热输送也同时导致了潮汐试验中北半球海冰面积增加。  相似文献   

暴时内辐射带高能质子的损失和恢复机制探究          下载免费PDF全文

陈洋  邹鸿  陈鸿飞  于向前  施伟红 《地球物理学报》2016,59(7):2344-2355

我们利用NOAA17卫星对内辐射带高能质子的观测结果研究了大磁暴期间内辐射带质子通量的变化过程.我们发现内辐射带质子出现两种不同的暴时损失事件.在大磁暴发生时,内辐射带外边界质子通量会迅速减小,然后缓慢恢复;而在内辐射带中心区的质子通量(即南大西洋异常区(SAA)质子通量最大值)的暴时变化表现为质子通量的一个迅速的减小和迅速恢复.内辐射带外边界的损失事件主要发生在较低能量质子能档,而内辐射带中心处的损失事件发生在所有质子能档.两种损失事件中质子通量的不同变化意味着内辐射带质子可能有不同的损失和产生机制.通过分析,我们认为内辐射带外边界处质子通量损失事件主要由磁场曲率散射机制造成,而其恢复机制主要是宇宙线反照中子衰变(CRAND).内辐射带中心区(即南大西洋异常区质子通量最大处)质子通量损失事件可能与Dst效应有关.  相似文献   

Suspended sediment delivery from small catchments to the Bay of Biscay. What are the controlling factors?          下载免费PDF全文

Ane Zabaleta  Iñaki Antiguedad  Irantzu Barrio  Jean‐Luc Probst 《地球表面变化过程与地形》2016,41(13):1894-1910

The transport and yield of suspended sediment (SS) in catchments all over the world have long been topics of great interest. This paper addresses the scarcity of information on SS delivery and its environmental controls in small catchments, especially in the Atlantic region. Five steep catchments in Gipuzkoa (Basque Country) with areas between 56 and 796 km² that drain into the Bay of Biscay were continuously monitored for precipitation, discharge and suspended sediment concentration (SSC) in their outlets from 2006 to 2013. Environmental characteristics such as elevation, slope, land‐use, soil depth and erodibility of the lithology were also calculated. The analysis included consideration of uncertainties in the SSC calibration models in the final suspended sediment yield (SSY) estimations. The total delivery of sediments from the catchments into the Bay of Biscay and its standard deviation was 272 200 ± 38 107 t yr.^?1, or 151 ± 21 t km^?2 yr.^?1, and the SSYs ranged from 46 ± 0.48 to 217 ± 106 t km^?2 yr.^?1. Hydroclimatic variables and catchment areas do not explain the spatial variability found in SSY, whereas land‐use (especially non‐native plantations) and management (human impacts) appear to be the main factors that control this variability. Obtaining long‐term measurements on sediment delivery would allow for the effects of environmental and human induced changes on SS fluxes to be better detected. However, the data provided in this paper offer valuable and quantitative information that will enable decision‐makers to make more informed decisions on land management while considering the effects of the delivery of SS. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Brazil's recent agenda on the sea and the South Atlantic contemporary scenario     

《Marine Policy》2017

The goal of this article is to present Brazil's interests and concerns in the South Atlantic, through the analysis of the ongoing governmental plans to its adjacent sea, and the security and defense issues in the ocean region. First, it will introduce four important programs, namely the Proarquipelago, Protrindade, Leplac, and Proarea, launched by the country after the entry into force of the United Nations Convention on the Law of the Sea. Then, it will discuss some of the domestic and international initiatives taken by Brazil to build a stable political and economic environment in the South Atlantic. Despite the peaceful purposes of the Brazilian agenda and policy to the sea, there are underlying reasons, such as keeping secure its oil and gas fields and consolidating its role as a major player in the ocean region, that must be considered as well. However, changes in the domestic scenario may provoke unprecedented modifications in this agenda.  相似文献   

The influence of initial conditions and open boundary conditions on shelf circulation in a 3D ocean-shelf model of the North East Atlantic   总被引：1，自引：0，他引：1  

Sarah L. Wakelin  Jason T. Holt  Roger Proctor 《Ocean Dynamics》2009,59(1):67-81

Data from climatology (World Ocean Atlas) and two large scale operational ocean models (Forecasting Ocean Assimilation Model (FOAM), UK Met. Office and the Navy Coastal Ocean Model (NCOM), US Naval Research Laboratory) are used to give initial and open boundary conditions for a northeast Atlantic implementation of the Proudman Oceanographic Laboratory Coastal Ocean Model System (POLCOMS). We study the effects of using the different datasets on the temperature fields and the circulation. On the continental shelf, comparisons of POLCOMS output with Advanced Very High Resolution Radiometer sea surface temperature data suggest that the effect of using different ocean model initial and boundary conditions is small and that, after 15 months of model time, the impact of the different initial conditions is negligible. Stronger evidence of influence is seen in the deeper oceanic regions of the domain. Volume fluxes through sections governing flow into and out of the North Sea, through the Irish Sea and along the shelf edge show that the impact of the different boundary conditions is small on the shelf but significant elsewhere. These results are contrasted with the use of climatology to assess the value of these Global Ocean Data Assimilation Experiment ocean model products.  相似文献   

Zoobotryon verticillatum Della Chiaje, 1822 (Bryozoa), a new occurrence in the archipelago of the Azores (North-Eastern Atlantic)     

Jaen Nieto Amat  Fernando Tempera 《Marine pollution bulletin》2009,58(5):761-764

The new occurrence of the bryozoan Zoobotryon verticillatum Della Chiaje, 1822 is herein recorded in multiple places throughout Azores archipelago. Where introduced, this species has caused important ecological and economical damage and therefore is regarded as invasive. In the Azores, no detrimental effects have yet been noted. The species is so far restricted to marinas (Horta, Faial Island; Vila Franca do Campo, São Miguel Island) and a natural coastal pool located near a secondary harbour (Lajes do Pico, Pico Island).A total of 29 colonies were counted during a specific survey conducted in August 2008 in the marina of Horta. The distribution of the species throughout the eastern and central island groups denotes a wide dispersion area and offers control or eradication measures a low probability of success together with the lack of harbour management practices that could effectively prevent the arrival, settlement and dispersal of non-native species transported by human-assisted means.  相似文献   

Actions taken by fishing Nations towards identification and protection of vulnerable marine ecosystems in the high seas: The Spanish case (Atlantic Ocean)     

P. Durán Muñoz  M. Sayago-Gil  F.J. Murillo  J.L. Del Río  L.J. López-Abellán  M. Sacau  R. Sarralde 《Marine Policy》2012,36(2):536-543

In reply to the United Nations General Assembly Resolutions on sustainable fisheries, Spain, either by itself or in collaboration with other Nations, has been carrying out studies on vulnerable marine ecosystems (VMEs) in the high seas of the Atlantic Ocean (areas beyond national jurisdictions) since 2005. Such studies provide advice to the Spanish Government, the Regional Fisheries Management Organizations and the European Union. This paper presents the multidisciplinary methodology used and summarises the following management results: (i) contribution to identification of cold-water corals and provision of evidence to close part (∼16,000 km²) of the Hatton Bank (NE Atlantic) to bottom fishing; (ii) compilation of an international data base to identify VMEs on the slopes of the Grand Banks of Newfoundland, Flemish Pass, and Flemish Cap (NW Atlantic) and to redefine areas currently closed to fishing; (iii) improvement of knowledge about deepwater ecosystems on Walvis Ridge and adjacent seamounts (SE Atlantic) as a pilot project for implementation in this region; and (iv) identification of VMEs and closure of an area (∼41,300 km²) on the high seas of the SW Atlantic. Also discussed are progress and challenges related to identifying and protecting VMEs.  相似文献   

Eocene post-rift tectonostratigraphy of the Rockall Plateau, Atlantic margin of NW Britain: Linking early spreading tectonics and passive margin response     

Martyn S. Stoker  Geoffrey S. Kimbell 《Marine and Petroleum Geology》2012,30(1):98-125

A regional study of the Eocene succession in the UK sector of the Rockall Plateau has yielded new insights into the early opening history of the NE Atlantic continental margin. Data acquired from British Geological Survey borehole 94/3, on the Rockall High, provides a high-resolution record of post-rift, Early to Mid-Eocene, subaqueous fan-delta development and sporadic volcanic activity, represented by pillow lavas, tuffs and subaerial lavas. This sequence correlates with the East Rockall Wedge, which is one of several prograding sediment wedges identified across the Rockall Plateau whose development was largely terminated in the mid-Lutetian. Linking the biostratigraphical data with the magnetic anomaly pattern in the adjacent ocean basin indicates that this switch-off in fan-delta sedimentation and volcanism was coincident with the change from a segmented/transform margin to a continuously spreading margin during chron C21. However, late-stage easterly prograding sediment wedges developed on the Hatton High during late Mid- to Late Eocene times; these can only have been sourced from the Hatton High, which was developing as an anticline during this interval. This deformation occurred in response to Mid- to Late Eocene compression along the ocean margin, possibly associated with the reorganisation to oblique spreading in the Iceland Basin, which culminated at the end of the Eocene with the formation of the North Hatton Anticline, and the deformation (tilting) of these wedges. A series of intra-Eocene unconformities, of which the mid-Lutetian unconformity is the best example, has been traced from the Rockall Plateau to the Faroe-Shetland region and onto the Greenland conjugate margin bordering the early ocean basin. Whilst there appears to be some correlation with 3rd order changes in eustatic sea level, it is clear from this study that tectonomagmatic processes related to changes in spreading directions between Greenland and Eurasia, and/or mantle thermal perturbations cannot be discounted.  相似文献   

Spatio-temporal analysis of the melt onset dates over Arctic sea ice from 1979 to 2017     

Shuang Liang  Jiangyuan Zeng  Zhen Li  Dejing Qiao 《海洋学报(英文版)》2022,41(4):146-156

The melt onset dates(MOD) over Arctic sea ice plays an important role in the seasonal cycle of sea ice surface properties, which impacts Arctic surface solar radiation absorbed by the ice-ocean system. Monitoring interannual variations in MOD is valuable for understanding climate change. In this study, we investigated the spatio-temporal variability of MOD over Arctic sea ice and 14 Arctic sub-regions in the period of 1979 to 2017 from passive microwave satellite data. A set of mathematical and ...  相似文献   

Broad-band calibration of marine seismic sources used by R/V Polarstern for academic research in polar regions     

Monika Breitzke  Olaf Boebel  Saad El Naggar  Wilfried Jokat  Berthold Werner 《Geophysical Journal International》2008,174(2):505-524

Air guns and air-gun arrays of different volumes are used for scientific seismic surveys with R/V Polarstern in polar regions. To assess the potential risk of these research activities on marine mammal populations, knowledge of the sound pressure field of the seismic sources is essential. Therefore, a broad-band (0–80 kHz) calibration study was conducted at the Heggernes Acoustic Range, Norway. A GI (2.4 l), a G (8.5 l) and a Bolt gun (32.8 l) were deployed as single sources, 3 GI (7.4 l), 3 G (25.6 l) and 8 VLF™ Prakla-Seismos air guns (24.0 l) as arrays. Each configuration was fired along a line of 3–4 km length running between two hydrophone chains with receivers in 35, 100, 198 and 263 m depth. Peak-to-peak, zero-to-peak, rms and sound exposure levels (SEL) were analysed as functions of range. They show the typical dipole-like directivity of marine seismic sources with amplitude cancellation close to the sea surface, higher amplitudes in greater depths, and sound pressure levels which continuously decrease with range. Levels recorded during the approach are lower than during the departure indicating a shadowing effect of Polarsterns's hull. Backcalculated zero-to-peak source levels range from 224–240 dB re 1 μPa @ 1 m. Spectral source levels are highest below 100 Hz and amount to 182–194 dB re 1 μPa Hz^–1. They drop off continuously with range and frequency. At 1 kHz they are ∼30 dB, at 80 kHz ∼60 dB lower than the peak level. Above 1 kHz amplitude spectra are dominated by Polarstern's self-noise. From the rms and sound exposure levels of the deepest hydrophone radii for different thresholds are derived. For a 180 dB rms-level threshold radii maximally vary between 200 and 600 m, for a 186 dB SEL threshold between 50 and 300 m.  相似文献