Effects of substrate differences on water availability for Arctic lichens during the snow-free summers in the High Arctic glacier foreland

We used observational and experimental analyses to investigate the photosynthetic activity and water relationships of five lichen species attached to different substrates in a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard (79°N) during the snow-free season in 2009 and 2010. After the rains ceased, lichens and their attached substrates quickly dried, whereas photosynthetic activity in the lichens decreased gradually. The in situ photosynthetic activity was estimated based on the relative electron transportation rate (rETR) in four fruticose lichens: Cetrariella delisei, Flavocetraria nivalis, Cladonia arbuscula ssp. mitis, and Cladonia pleurota. The rETR approached zero around noon, although the crustose lichen Ochrolechia frigida grown on biological soil crust (BSC) could acquire water from the BSC and retain its WC to perform positive photosynthesis. The light-rETR relationship curves of the five well-watered lichens were characterized into two types: shade-adapted with photoinhibition for the fruticose lichens, and light-adapted with no photoinhibition for O. frigida. The maximum rETR was expected to occur when they could acquire water from the surrounding air or from substrates during the desiccation period. Our results suggest that different species of Arctic lichens have different water availabilities due to their substrates and/or morphological characteristics, which affect their photosynthetic active periods during the summer.     

Changes to the Canadian Arctic Archipelago Sea Ice and Freshwater Fluxes in the Twenty-First Century under the Intergovernmental Panel on Climate Change A1B Climate Scenario

A coupled ocean and sea-ice pan-Arctic model forced by the Intergovernmental Panel on Climate Change A1B climate scenario is used to study the evolution of ice and ocean surface conditions within the Canadian Arctic Archipelago (CAA) during the twenty-first century. A summer ice-free CAA is likely by the end of our simulation. Sea ice undergoes significant changes from the mid-2020s to the mid-2060s in both concentration and thickness. The simulation shows a shrinking of 65% and a thinning of 75% in summer over the 40 years, resulting in a partially open Northwest Passage by the 2050s. However, ice in central Parry Channel might increase due to a decrease in export from April to June, linked to a reduced cross-channel sea surface height (SSH) gradient, before melting thermodynamically. On a larger scale, the central CAA throughflow will experience a significant decrease in both volume and freshwater transport after 2020, which is related to the change in the SSH difference between the two ends of Parry Channel, particularly the lifting of SSH in Baffin Bay. With a lower albedo, a warmer ocean is simulated, particularly in summer. The sea surface salinity within the CAA demonstrates a strong decadal oscillation without a clear trend over the entire simulation. A north–south pattern, separated by Parry Channel, is also found in the changes of ocean temperature and salinity fields due to different ice conditions.     

Dominant patterns of winter Arctic surface wind variability

Dominant statistical patterns of winter Arctic surface wind(WASW) variability and their impacts on Arctic sea ice motion are investigated using the complex vector empirical orthogonal function(CVEOF) method. The results indicate that the leading CVEOF of Arctic surface wind variability, which accounts for 33% of the covariance, is characterized by two different and alternating spatial patterns(WASWP1 and WASWP2). Both WASWP1 and WASWP2 show strong interannual and decadal variations, superposed on their declining trends over past decades. Atmospheric circulation anomalies associated with WASWP1 and WASWP2 exhibit, respectively, equivalent barotropic and some baroclinic characteristics, differing from the Arctic dipole anomaly and the seesaw structure anomaly between the Barents Sea and the Beaufort Sea. On decadal time scales, the decline trend of WASWP2 can be attributed to persistent warming of sea surface temperature in the Greenland—Barents—Kara seas from autumn to winter, reflecting the effect of the Arctic warming. The second CVEOF, which accounts for 18% of the covariance, also contains two different spatial patterns(WASWP3 and WASWP4). Their time evolutions are significantly correlated with the North Atlantic Oscillation(NAO) index and the central Arctic Pattern, respectively, measured by the leading EOF of winter sea level pressure(SLP) north of 70°N. Thus, winter anomalous surface wind pattern associated with the NAO is not the most important surface wind pattern. WASWP3 and WASWP4 primarily reflect natural variability of winter surface wind and neither exhibits an apparent trend that differs from WASWP1 or WASWP2. These dominant surface wind patterns strongly influence Arctic sea ice motion and sea ice exchange between the western and eastern Arctic. Furthermore, the Fram Strait sea ice volume flux is only significantly correlated with WASWP3. The results demonstrate that surface and geostrophic winds are not interchangeable in terms of describing wind field variability over the Arctic Ocean. The results have important implications for understanding and investigating Arctic sea ice variations: Dominant patterns of Arctic surface wind variability, rather than simply whether there are the Arctic dipole anomaly and the Arctic Oscillation(or NAO), effectively affect the spatial distribution of Arctic sea ice anomalies.     

Numerical simulation of the impact of underlying surface changes on Arctic climate

Using a regional atmospheric model for Arctic climate simulation, two groups of numerical experiments were carried out to study the inlfuence of changes in the underlying surface (land surface, sea sur...     

Large-scale oil-in-ice experiment in the Barents Sea: monitoring of oil in water and MetOcean interactions

A large-scale field experiment took place in the marginal ice zone in the Barents Sea in May 2009. Fresh oil (7000 L) was released uncontained between the ice floes to study oil weathering and spreading in ice and surface water. A detailed monitoring of oil-in-water and ice interactions was performed throughout the six-day experiment. In addition, meteorological and oceanographic data were recorded for monitoring of the wind speed and direction, air temperature, currents and ice floe movements. The monitoring showed low concentrations of dissolved hydrocarbons and the predicted acute toxicity indicated that the acute toxicity was low. The ice field drifted nearly 80 km during the experimental period, and although the oil drifted with the ice, it remained contained between the ice floes.     

Improving benthic monitoring by combining trawl and grab surveys

Environmental monitoring is performed on seafloor communities since these organisms are relatively stationary and integrate the environmental conditions over many years. Standard practices involve sampling by grab. Epifaunal taxa, often missed by grab sampling, are likely to have different ecological functions. We investigate how current environmental assessments represent the benthic community as a whole by comparing taxonomic and functional components sampled by grabs and epibenthic trawls. Faunal communities sampled by trawl (filtrating or predator, epifauna) and grab (infaunal, detrivore) differs widely by sampling distinct functional components, and these may be expected to respond to different human-induced stressors. Neither component appears to be a good surrogate for the community as a whole. We suggest a benthic monitoring by combining both techniques. Sustainable ecosystem functioning is intimately tied to the health of both components of the benthic community, and is recognized as an important goal by signatories of the Convention on Biological Diversity.     

北极沿岸地区水体中氢氧稳定同位素组成及水分转化过程研究

2010年7月参加第三届北京中学生北极科学考察活动,收集了北极沿岸地区的挪威斯瓦尔巴德群岛(Svalbard)、冰岛、格陵兰沿岸地区的海水、沿岸海水、海冰表面冰样、地表径流等水体样品,对样品进行了氢氧稳定同位素成分测定,分析了北极沿岸地区水体的水循环过程.结果表明,该地区不同水体中的稳定同位素具有不同特征.沿岸海水中δ...     

Selected Trace Elements in Snowpack on Urumqi Glacier No. 1, Eastern Tianshan, China: As Yielded by Leaching Treatment Representative of Real-World Environmental Conditions

To investigate the seasonal variability and potential environmental significance of trace elements in mountain glaciers, the surface snow and snow pit samples were collected at Urumqi Glacier No. 1 (43o06'N, 86o49'E, 4 130 m a.s.l.), eastern Tianshan (天山), from September 2002 to September 2003, and analyzed for Li, V, Cr, Mn, Co, Cu, and Ba. The samples were acidified (leached) in a manner intended to reasonably approximate the extent to which the natural hydrologic and weathering cycles would liberate elem...     

北冰洋浮冰站近地层参数的观测估算

利用2008年8月20～27日我国第3次北极考察队在85°N附近设立的冰站上进行的湍流通量、辐射观测所获取的相关资料,采用涡动相关法对夏季北冰洋浮冰下垫面的近地层参数进行了估算.结果显示,观测期间浮冰区冰雪面的平均感热、潜热和净辐射通量分别是0.2 W/m2,1.2 W/m2和9.9 W/m2,表明下垫面获得的大部分热...