1928 research outputs found
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An ice-ocean model study to explore climate change mechanisms in comparison with interannual-to-decadal variability of geochemical tracers
Get PDFOne way to identify the mechanisms that are crucial to Arctic climate change is to use existing data that exhibit interannual-to-decadal variability in the sea ice and ocean interior due to atmospheric forcing. Since around 1960s, valuable geochemical data of the ocean interior, together with atmospheric and sea ice data, have been analyzed and examined in a coupled ice–ocean model with an idealized configuration of the Arctic Basin. This is fundamentally driven by negative salt flux, in addition to atmospheric circulation and cooling. This strategy has a clear advantage over more sophisticated models with higher resolution that require extensive data collections for verification. Around 1990, the dominant atmospheric mode shifted from the Northern Annular Mode (NAM) to the Arctic Dipole Mode (ADM). The variability of sea ice cover was explained by these two modes sequentially and reproduced in the model. In particular, the geochemical fields indicated a movement of the Transpolar Drift Stream due to the NAM and an oscillation of the Pacific water between the Atlantic and Pacific sides due to the ADM. Both these features were reproduced reasonably well by the oceanic tracers in the model, including the time lags of about one third of the oscillation periods. Thus, this strategy can suggest methods and locations for monitoring oceanographic responses to Arctic climate change
Numerical simulation of the dynamic characteristics of flow fields under ice
Get PDFAtmospheric and oceanic drag are the main environmental forces controlling sea ice drift. Oceanic drag includes the form drag generated by water pressure gradients on the side of ice floes or on ice ridges, and the skin friction generated by viscous flow on the bottom of ice floes. In this study, we carried out a two-dimensional numerical simulation using FLUENT software to investigate the characteristics of dynamic flow under ice with a smooth undersurface. We studied water drag and flow field distribution below the ice under different conditions of ice draft and flow velocity, and the results agreed well with data from laboratory-based physical modeling tests, demonstrating the ability of the numerical model to reproduce the dynamic interactions between sea ice and the flow field. The degree of distortion in the flow field caused by ice increased as the ice draft increased. Vortexes occurred in the wake field of the floe, and the centers of the vortexes moved away from the ice with increasing ice draft. The simulated drag of water on ice showed a clear linear relationship with the square of the flow velocity
Links between Arctic sea ice and extreme summer precipitation in China: an alternative view
Get PDFPotential links between the Arctic sea-ice concentration anomalies and extreme precipitation in China are explored. Associations behind these links can be explained by physical interpretations aided by visualisations of temporarily lagged composites of variables such as atmospheric mean sea level pressure and sea surface temperature. This relatively simple approach is verified by collectively examining already known links between the Arctic sea ice and rainfall in China. For example, similarities in the extreme summer rainfall response to Arctic sea-ice concentration anomalies either in winter (DJF) or in spring (MAM) are highlighted. Furthermore, new links between the Arctic sea ice and the extreme weather in India and Eurasia are proposed. The methodology developed in this study can be further applied to identify other remote impacts of the Arctic sea ice variability
Gap Analysis Report
Get PDFThe Gap Analysis Report (GAR) is a deliverable within
the Preparatory Action “Strategic Environmental Impact
Assessment of development of the Arctic.” The report
evaluates existing Arctic information needs and exchange
in order to help assess how an EU Arctic Information
Centre could improve information provision and
communication. The goals of the GAR are two-fold: First,
it aims to identify and analyze the Arctic information
needs of stakeholders and policy-makers. Second, the
GAR endeavours to offer recommendations on ways to
improve knowledge (reducing information gaps) and to
improve two-way communication between information
providers and users (reducing communication gaps).
Recommendations are designed to reflect the role,
or roles, of an EU Arctic Information Centre. Through
meeting these objectives, the GAR ultimately supports
the Preparatory Action’s goals of evaluating a potential
EU Arctic Information Centre and network
Strategic Assessment Of Development Of The Arctic - Assessment conducted for theEuropean Union
Get PDFThe ‘Strategic Assessment of Development of the Arctic:
Assessment Conducted for the European Union” report
considers the trends and developments taking place in the
European Arctic today. That includes a view to 2030, with
an emphasis on the uncertainties. The analysis has been
conducted on the basis of seven themes focused on change.
The implications of Arctic changes for the European Union
as well as the role of EU policies and actions in the Arctic are examined. The European Arctic is understood here as the part of the circumpolar Arctic located between Greenland and northwest Russia
European Arctic Initiatives compendium
Get PDFThe European Arctic Initiatives compendium presents
flagship initiatives undertaken by the European Union
in Arctic regions, as well as initiatives undertaken by
member states and actors operating within states
belonging to the European Union (EU). Furthermore, it
includes initiatives by European states such as Norway
and Iceland, as well as territories such as Greenland,
which are highly relevant in the context of the European
Arctic, and in many cases strongly linked to the EU,
for example, the European Research Area (ERA).
The compendium has been compiled as part of the
Preparatory Action for a Strategic Environmental Impact
Assessment of the Arctic.
The compendium’s aim is three-fold: to assist in an Arctic
Information Centre feasibility study; to provide a window
onto Arctic initiatives that may inform the European
Arctic Impact Assessment (EUAIA) which forms part of
the Preparatory Action; and to inform the European
Commission on European Arctic Initiatives
Phylogenetic analysis and in vitro culture of mosses from the Antarctic Fildes Peninsula
Get PDFMolecular genetic techniques have proven very useful for initial analysis of the extent of genetic variation and dispersal in several Antarctic moss species. In the present study, the small subunit ribosomal RNA (SSU rDNA) and internal transcribed spacers of the nuclear ribosomal DNA (ITS rDNA) were sequenced in nine individuals of different mosses from the Fildes Peninsula of Antarctica. Sequence alignment showed that the extreme environment tended to increase the genetic diversity of Antarctic mosses. In addition, in our phylogenetic analysis, one previously unidentified Antarctic moss species was characterized by comparison with SSU and ITS rDNA sequences of known moss species. Moreover, the optimal culture medium and conditions for surface explant sterilization and protonemata induction in tissue culture of Pohlia nutans were investigated. The successful establishment of a tissue culture protocol together with the phylogenetic analysis of Antarctic mosses will provide technological support to establish an effective resource regeneration method for discovering new functional genes and gaining novel insights into the mechanisms of stress acclimation
The distribution and characteristics of suspended particulate matter in the Chukchi Sea
Get PDFSamples taken from the Chukchi Sea (CS) during the 4th Chinese National Arctic Research Expedition, 2010, were analyzed to determine the content and composition of suspended particulate matter (SPM) to improve our understanding of the distribution, sources and control factors of the SPM there. The results show that the SPM in the water column is highest in the middle and near the bottom in the south and central–north CS, followed by that off the Alaskan coast and in Barrow Canyon. The SPM content is lowest in the central CS. Scanning electron microscope (SEM) analysis shows that the SPM in the south and central–north CS is composed mainly of diatoms, but the dominant species in those two areas are different. The SPM off the Alaskan coast and in Barrow Canyon is composed mainly of terrigenous material with few bio-skeletal clasts. The distribution of temperature and salinity and the correlation between diatom species in SPM indicate that the diatom dominant SPM in the south CS is from the Pacific Ocean via the Bering Strait in summer. The diatom dominant SPM in the central–north CS is also from Pacific water, which reaches the CS in winter. The SPM in the middle and near the bottom of the water column off the Alaskan coast and in Barrow Canyon is from Alaskan coastal water and terrigenous material transported by rivers in Alaska
Source and spatial distributions of particulate organic carbon and its isotope in surface waters of Prydz Bay, Antarctica, during summer
Get PDFIn this study, we investigated the distributions of sea-surface suspended particulate organic carbon (POC) and its stable isotope (δ13CPOC) in Prydz Bay, Antarctica, and examined the factors influencing their distribution, sources, and transport. We used measurements collected from 61 stations in Prydz Bay during the 29th Chinese National Antarctic Research Expedition, in combination with remote sensing data on sea surface temperature (SST), chlorophyll a concentration, and sea ice coverage. The POC concentration in the surface waters of Prydz Bay was 0.28–0.84 mg·L−1, with an average concentration of 0.48 mg·L−1. The δ13CPOC value ranged from −29.68‰ to −26.30‰, with an average of −28.01‰. The concentration of suspended POC was highest in near-shore areas and in western Prydz Bay. The POC concentration was correlated with chlorophyll a concentration and sea ice coverage, suggesting that POC was associated with phytoplankton production in local water columns, while the growth of phytoplankton was obviously affected by sea ice coverage. The δ13CPOC value in suspended particles decreased gradually towards the outer waters of Prydz Bay, while in eastern Prydz Bay the δ13CPOC value become gradually more negative from nearshore to deep-water areas, suggesting that δ13CPOC was mainly infl uenced by CO2 fi xation by phytoplankton. The δ13CPOC value in suspended particles near Zhongshan Station was signifi cantly negative, possibly as a result of the input of terrigenous organic matter and changes in the phytoplankton species composition in the nearshore area