Surface salinity fields in the Arctic Ocean and statistical approaches to predicting anomalies and patterns

Significant salinity anomalies have been observed in the Arctic Ocean surface layer during the last decade. Using gridded data of winter salinity in the upper 50 m layer of the Arctic Ocean for the period 1950-1993 and 2007-2012, we investigated the inter-annual variability of the salinity fields, attempted to identify patterns and anomalies, and developed a statistical model for the prediction of surface layer salinity. The statistical model is based on linear regression equations linking the principal components with environmental factors, such as atmospheric circulation, river runoff, ice processes, and water exchange with neighboring oceans. Using this model, we obtained prognostic fields of the surface layer salinity for the winter period 2013-2014. The prognostic fields demonstrated the same tendencies of surface layer freshening that were observed previously. A phase portrait analysis involving the first two principal components exhibits a dramatic shift in behavior of the 2007-2012 data in comparison to earlier observations

Variations in characteristics of the barents branch of the Atlantic Water in the Nansen Basin under the influence of atmospheric circulation over the Barents Sea

The thermohaline structure of the Arctic Basin (AB) of the Arctic Ocean (AO) is determined to a great extent by an intermediate water layer existing under ice at a depth varying from 100 to 700–1000 m. The water layer is formed by warm North Atlantic Water (AW), which enters the AB by two ways: through Fram Strait and the Barents Sea (Fig. 1). The AW arriving to the AB via Fram Strait extends further eastward along the continental slope of the Eurasian Arctic region and forms the Fram Branch (FBAW). The Barents Branch of the AW (BBAW) was formed by the North Atlantic Water entering the Barents Sea between the Spitsbergen Archipelago and the Scandinavian Peninsula. Both branches merge in the northern Kara Sea

On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

In this paper, we investigate the seasonal and spatial variability of stratification on the Siberian shelves with a case study from the Laptev Sea based on shipboard hydrographic measurements, year-round oceanographic mooring records from 2013 to 2014 and chemical tracer-based water mass analyses. In summer 2013, weak onshore-directed winds caused spreading of riverine waters throughout much of the eastern and central shelf. In contrast, strong southerly winds in summer 2014 diverted much of the freshwater to the northeast, which resulted in 50% less river water and significantly weaker stratification on the central shelf compared with the previous year. Our year-long records additionally emphasize the regional differences in water column structure and stratification, where the northwest location was well-mixed for 6 months and the central and northeast locations remained stratified into spring due to the lower initial surface salinities of the river-influenced water. A 26 year record of ocean reanalysis highlights the region’s interannual variability of stratification and its dependence on winds and sea ice. Prior the mid-2000s, river runoff to the perennially ice-covered central Laptev Sea shelf experienced little surface forcing and river water was maintained on the shelf. The transition toward less summer sea ice after the mid-2000s increased the ROFI’s (region of freshwater influence) exposure to summer winds. This greatly enhanced the variability in mixed layer depth, resulting in several years with well-mixed water columns as opposed to the often year-round shallow mixed layers before. The extent of the Lena River plume is critical for the region since it modulates nutrient fluxes and primary production, and further controls intermediate heat storage induced by lateral density gradients, which has implications for autumnal freeze-up and the eastern Arctic sea ice volume. MAIN POINTS 1. CTD surveys and moorings highlight the regional and temporal variations in water column stratification on the Laptev Sea shelf. 2. Summer winds increasingly control the extent of the region of freshwater influence under decreasing sea ice. 3. Further reductions in sea ice increases surface warming, heat storage, and the interannual variability in mixed layer depth

The First Training Workshop on Permafrost Research Methods: IMPETUS 2007 : OSL-APECS-PYRN Training Workshop; St. Petersburg, Russia, 29 November to 2 December 2007

Fifty young researchers from 14 countries met in St. Petersburg, Russia, to learn about the latest methods used in permafrost research and engineering and to discuss future plans to address climate change issues in permafrost areas. This workshop was an official International Polar Year (IPY) event organized jointly by the Otto Schmidt Laboratory for Polar and Marine Sciences (OSL) in St. Petersburg, the Permafrost Young Researchers Network (PYRN), and the Association of Polar Early Career Scientists (APECS). The workshop provided insights into the latest techniques and methods used in permafrost research in fields as diverse as permafrost modeling, investigations of mountain ice segregation, bubbling from thermokarst lakes, and submarine permafrost detection. It brought together experts to provide young investigators with a multidisciplinary and cross-border perspective on permafrost research, a much needed approach in a discipline marked by strong research history yet strongly entangled within national borders. Presentations and speaker biographies are now available on the conference Web site (http://pyrn.ways.org/activities/pyrn-meetings/2007-saint-petersburg)

Seasonal variability in Atlantic water off Spitsbergen

A combination of 2-year-long mooring-based measurements and snapshot conductivity–temperature–depth (CTD) observations at the continental slope off Spitsbergen (81°30′N, 31°00′E) is used to demonstrate a significant hydrographic seasonal signal in Atlantic Water (AW) that propagates along the Eurasian continental slope in the Arctic Ocean. At the mooring position this seasonal signal dominates, contributing up to 50% of the total variance. Annual temperature maximum in the upper ocean (above 215 m) is reached in mid-November, when the ocean in the area is normally covered by ice. Distinct division into ‘summer’ (warmer and saltier) and ‘winter’ (colder and fresher) AW types is revealed there. Estimated temperature difference between the ‘summer’ and ‘winter’ waters is 1.2 °C, which implies that the range of seasonal heat content variations is of the same order of magnitude as the mean local AW heat content, suggesting an important role of seasonal changes in the intensity of the upward heat flux from AW. Although the current meter observations are only 1-year long, they hint at a persistent, highly barotropic current with little or no seasonal signal attached

Russian-German collaboration in the arctic environmental research

The overview of the 20-years joint Russian-German multidisciplinary researches in the Arctic are represented in this article. Data were obtained during numerous marine and terrestrial expeditions, all-year-round measurements and observations. On the basis of modern research methods including satellite observation, radiocarbon (AMS 14C) dating of the Arctic sea sediments, isotope, biochemical and other methods, the new unique records were obtained. Special emphasis devoted to the latest data concerning modern sea-ice, ocean and sedimentation processes, evolution of the permafrost and paleoenvironments in the Laptev Sea System

Krupnomasshtabnye izmeneniya atlanticheskikh vod v Arkticheskom Basseine (Large-scale and interannual variability of the Atlantic water in the Arctic Ocean, in Russian)

The long-term variability of the intermediate Atlantic Water (AW) layer in the Arctic Ocean is analyzed. We reveal a positive temperature and negative salinity linear trends for the entire Arctic Ocean. Warming and cooling tendencies in the Canada Basin lags those for the Eurasian Basin by 9-10 years with similar duration for the warming and cooling periods for both basins. In contrast, salinity tendency in the Canada Basin lags those in the Eurasian Basins by 8-16 years salinity, and durationof saltier and fresher anomalies is different. The interannual variability for the depth of AW upper boundary and AW core temperature is studiedusing two first modes of the Empirical Orthogonal Function (EOF) decomposition exhibit unique patterns that have been never observed over the entire period of instrumental observations. For 2009, our analysis reveals the AW recovery to already observed patterns. our examination also shows that the AW warming and cooling is also accompanied by changes in depthsof the AW upper boundary and the AW core that provides evidence for the different volume and properties of the AW during warmer and cooler phases. In this respect, the AW warming in 1950s, 1990s differs from those in during the International Polar Year 2007/200

Sostoyanie sloya atlanticheskikh vod v Severnom Ledovitom okeane v 2007-2009 gg. (The state of Atlantic water layer in the Arctic Ocean in 2007-2009, in Russian)

Oceanographic studies during IPY 2007/2009 provided new information on spatial variability of hydrographic parameters. Detailed pattern of irregularities in the Atlantic Water (AW) layer was documented in the Nansen Basin. Spatial scales of temperature distribution and the depth of the upper boundary of AW were estimated. In the Canadian Basin spatial variations of temperature were less pronounced. During IPY 2007/2008 the area occupied by AW has increased. According to our estimations the positive temperature anomaly in some regions was as high as 1,5°C, which is about 70% of temperature maximum in 1950-1959. The upper boundary of AW (zero degree isotherm) rose by 40-120 m around the Mendeleyev Ridge and in the Amundsen Basin. At the same time, in the Canada Basin and in the western Fram Strait the AW thickness decreased by similar value. Heat content of the AW layer around the major part of the Arctic Ocean exceeded mean climatic value, except for the compact area north of Franz Josef Land, where small negative anomaly was observed. Throughout 2008 mean temperature and maximum temperature in the AW layer were higher than mean climatic values. At the same time, the state of AW layer in the inflow region, east of Fram Strait along the continental margin to the Laptev Sea, substantially changed in comparison with 2007. Mean and maximum temperature of AW dropped by 0,25/0,5°C. Heat content and the Thickness of AW layer have also decreased. Basing on the obtained results, we conclude that during 2008/2009 there was a neneral reverse trend in AW parameters towards mean climatic results

Ekstremaľnye izmeneniya temperatury i solenosti vody arkticheskogo poverkhnostnogo sloya v 2007-2009 gg. (The extreme changes of temperature and salinity in the Arctic Ocean surface layer in 2007-2009, in Russian)

This paper examines the temperature and salinity patterns and evolution in the surface layer of the Arctic Ocean in 2007-2009 and deals with the factors impacting the extreme changes both in temperature and salinity in 2007. The large areas of positive and negative anomalies in temperature and salinity have been formed over the Arctic Ocean with the apparant frontal barrier areea between Eurasian and American basins. The followed years (2008-2009) exhibit the reducing of thermohaline anomalies between the two basins assuming gradually rcovering to the initial state. Considering the mean salinities within 5-50 m depth one can claim that the positive linear trend is evident both in Eurasian and American basinss since 1950 to 1993 while the intensive freshening was obsserved in American basin in 2007-2009. We intend that these changes in salinity can be assumed as the signature of non-stationary nature of all Arctic marine environments