WorldWideScience

Sample records for arctic ice dynamics

  1. SEDNA: Sea ice Experiment - Dynamic Nature of the Arctic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sea Ice Experiment - Dynamic Nature of the Arctic (SEDNA) is an international collaborative effort to improve the understanding of the interaction between sea...

  2. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    Science.gov (United States)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-05-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The raw model reforecasts show large biases in Arctic sea ice area, mainly due to a differently simulated seasonal cycle and long term trend compared to observations. This translates very quickly (1-3 months) into large biases. We find that (heteroscedastic) extended logistic regressions are viable ensemble calibration methods, as the forecast skill is improved compared to standard bias correction methods. Analysis of regional skill of Arctic sea ice shows that the Northeast Passage and the Kara and Barents Sea are most predictable. These results show the importance of reducing model error and the potential for ensemble calibration in improving skill of seasonal forecasts of Arctic sea ice.

  3. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    NARCIS (Netherlands)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-01-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The

  4. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    NARCIS (Netherlands)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-01-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The ra

  5. Climate states and variability of Arctic ice and water dynamics during 1946–1997

    OpenAIRE

    Proshutinsky, Andrey Y.; Polyakov, Igor V; Johnson, Mark A.

    1999-01-01

    Recently observed changes in the Arctic have highlighted the need for a better understanding of Arctic dynamics. This research addresses that need and is also motivated by the recent finding of two regimes of Arctic ice - ocean wind-driven circulation. In this paper, we demonstrate that during 1946-1997 the Arctic environmental parameters have oscillated with a period of 10-15 years. Our results reveal significant differences among atmosphere, ice, and ocean processes during the anticyclonic ...

  6. Recent changes in the dynamic properties of declining Arctic sea ice: A model study

    Science.gov (United States)

    Zhang, Jinlun; Lindsay, Ron; Schweiger, Axel; Rigor, Ignatius

    2012-10-01

    Results from a numerical model simulation show significant changes in the dynamic properties of Arctic sea ice during 2007-2011 compared to the 1979-2006 mean. These changes are linked to a 33% reduction in sea ice volume, with decreasing ice concentration, mostly in the marginal seas, and decreasing ice thickness over the entire Arctic, particularly in the western Arctic. The decline in ice volume results in a 37% decrease in ice mechanical strength and 31% in internal ice interaction force, which in turn leads to an increase in ice speed (13%) and deformation rates (17%). The increasing ice speed has the tendency to drive more ice out of the Arctic. However, ice volume export is reduced because the rate of decrease in ice thickness is greater than the rate of increase in ice speed, thus retarding the decline of Arctic sea ice volume. Ice deformation increases the most in fall and least in summer. Thus the effect of changes in ice deformation on the ice cover is likely strong in fall and weak in summer. The increase in ice deformation boosts ridged ice production in parts of the central Arctic near the Canadian Archipelago and Greenland in winter and early spring, but the average ridged ice production is reduced because less ice is available for ridging in most of the marginal seas in fall. The overall decrease in ridged ice production contributes to the demise of thicker, older ice. As the ice cover becomes thinner and weaker, ice motion approaches a state of free drift in summer and beyond and is therefore more susceptible to changes in wind forcing. This is likely to make seasonal or shorter-term forecasts of sea ice edge locations more challenging.

  7. A study of Arctic sea ice freeboard heights, gravity anomalies and dynamic topography from ICESat measurementes

    DEFF Research Database (Denmark)

    Skourup, Henriette

    The Arctic sea ice cover has a great influence on the climate and is believed to respond rapidly to climate changes. Since 2003 the Ice, Cloud and land Elevation Satellite (ICESat) laser altimetry mission has provided satellite altimetry over the ice covered Arctic Ocean up to 86 N. In this thesis...... surface can be used to improve the knowledge of the sea surface topography (semi permanent circulation patterns). The dynamic topography observed by ICESat maps the main circulation in the Arctic, e.g. the Beaufort Gyre and the lower heights in the Norwegian-Greenland Sea. A comparison to existing global...

  8. Stochastic dynamics of Arctic sea ice Part I: Additive noise

    CERN Document Server

    Moon, Woosok

    2015-01-01

    We analyze the numerical solutions of a stochastic Arctic sea ice model with constant additive noise over a wide range of external heat-fluxes, $\\Delta F_0$, which correspond to greenhouse gas forcing. The variability that the stochasticity provides to the deterministic steady state solutions (perennial and seasonal ice states) is illustrated by examining both the stochastic paths and probability density functions (PDFs). The principal stochastic moments (standard deviation, mean and skewness) are calculated and compared with those determined from a stochastic perturbation theory described previously by Moon and Wettlaufer (2013). We examine in detail the competing roles of the destabilizing sea ice-albedo-feedback and the stabilizing long-wave radiative loss contributions to the variability of the ice cover under increased greenhouse-gas forcing. In particular, the variability of the stochastic paths at the end of summer shows a clear maximum, which is due to the combination of the increasing importance of t...

  9. Applying High Resolution Imagery to Understand the Role of Dynamics in the Diminishing Arctic Sea Ice Cover

    Science.gov (United States)

    2015-09-30

    Role of Dynamics in the Diminishing Arctic Sea Ice Cover ” Dr. Sinead L. Farrell University of Maryland, ESSIC, 5825 University Research Court...day Arctic ice cover , enabling the improvement of models used to forecast ice drift. APPROACH Our research is centered on the application of...resolution visible band imagery for deriving geophysical information on the sea ice pack of the Arctic Ocean , and improve understanding of key

  10. Lagrangian analysis of sea-ice dynamics in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Sándor Szanyi

    2016-11-01

    Full Text Available In this study, we present Lagrangian diagnostics to quantify changes in the dynamical characteristics of the Arctic sea-ice cover from 2006 to 2014. Examined in particular is the evolution in finite-time Lyapunov exponents (FTLEs, which monitor the rate at which neighbouring particle trajectories diverge, and stretching rates throughout the Arctic. In this analysis, we compute FTLEs for the Arctic ice-drift field using the 62.5 km daily sea-ice motion vector data from the European Organisation for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facility. Results from the FTLE analysis highlight the existence of three distinct dynamical regions with strong stretching, captured by FTLE maxima or ridges. It is further shown that FTLE ridges are dominated by shear, with contributions from divergence in the Beaufort Sea. Localization of FTLE features following the 2012 record minimum in summertime sea-ice extent illustrates the emergence of an Arctic characterized by increased mixing. Results also demonstrate higher FTLEs in years when lower multi-year ice extent is observed.

  11. Arctic Summer Ice Processes

    Science.gov (United States)

    Holt, Benjamin

    1999-01-01

    The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open

  12. Stochastic dynamics of Arctic sea ice Part II: Multiplicative noise

    CERN Document Server

    Moon, Woosok

    2015-01-01

    We analyze the numerical solutions of a stochastic Arctic sea ice model with multiplicative noise over a wide range of external heat-fluxes, $\\Delta F_0$, which correspond to greenhouse gas forcing. When the noise is multiplicative, the noise-magnitude depends on the state-variable, and this will influence the statistical moments in a manner that differs from the additive case, which we analyzed in Part I of this study. The state variable describing the deterministic backbone of our model is the energy, $E(t)$, contained in the ice or the ocean and for a thorough comparison and contrast we choose the simplest form of multiplicative noise $\\sigma E(t) \\xi(t)$, where $\\sigma$ is the noise amplitude and $\\xi(t)$ is the noise process. The case of constant additive noise (CA) we write as $\\sigma\\overline{E_S}\\xi(t)$, in which $\\overline{E_S}$ is the seasonally averaged value of the periodic deterministic steady-state solution $E_S(t)$, or the deterministic seasonal cycle. We then treat the case of seasonally-varyi...

  13. Sea ice thermohaline dynamics and biogeochemistry in the Arctic Ocean: Empirical and model results

    Science.gov (United States)

    Duarte, Pedro; Meyer, Amelie; Olsen, Lasse M.; Kauko, Hanna M.; Assmy, Philipp; Rösel, Anja; Itkin, Polona; Hudson, Stephen R.; Granskog, Mats A.; Gerland, Sebastian; Sundfjord, Arild; Steen, Harald; Hop, Haakon; Cohen, Lana; Peterson, Algot K.; Jeffery, Nicole; Elliott, Scott M.; Hunke, Elizabeth C.; Turner, Adrian K.

    2017-07-01

    Large changes in the sea ice regime of the Arctic Ocean have occurred over the last decades justifying the development of models to forecast sea ice physics and biogeochemistry. The main goal of this study is to evaluate the performance of the Los Alamos Sea Ice Model (CICE) to simulate physical and biogeochemical properties at time scales of a few weeks and to use the model to analyze ice algal bloom dynamics in different types of ice. Ocean and atmospheric forcing data and observations of the evolution of the sea ice properties collected from 18 April to 4 June 2015, during the Norwegian young sea ICE expedition, were used to test the CICE model. Our results show the following: (i) model performance is reasonable for sea ice thickness and bulk salinity; good for vertically resolved temperature, vertically averaged Chl a concentrations, and standing stocks; and poor for vertically resolved Chl a concentrations. (ii) Improving current knowledge about nutrient exchanges, ice algal recruitment, and motion is critical to improve sea ice biogeochemical modeling. (iii) Ice algae may bloom despite some degree of basal melting. (iv) Ice algal motility driven by gradients in limiting factors is a plausible mechanism to explain their vertical distribution. (v) Different ice algal bloom and net primary production (NPP) patterns were identified in the ice types studied, suggesting that ice algal maximal growth rates will increase, while sea ice vertically integrated NPP and biomass will decrease as a result of the predictable increase in the area covered by refrozen leads in the Arctic Ocean.

  14. Arctic ice management

    Science.gov (United States)

    Desch, Steven J.; Smith, Nathan; Groppi, Christopher; Vargas, Perry; Jackson, Rebecca; Kalyaan, Anusha; Nguyen, Peter; Probst, Luke; Rubin, Mark E.; Singleton, Heather; Spacek, Alexander; Truitt, Amanda; Zaw, Pye Pye; Hartnett, Hilairy E.

    2017-01-01

    As the Earth's climate has changed, Arctic sea ice extent has decreased drastically. It is likely that the late-summer Arctic will be ice-free as soon as the 2030s. This loss of sea ice represents one of the most severe positive feedbacks in the climate system, as sunlight that would otherwise be reflected by sea ice is absorbed by open ocean. It is unlikely that CO2 levels and mean temperatures can be decreased in time to prevent this loss, so restoring sea ice artificially is an imperative. Here we investigate a means for enhancing Arctic sea ice production by using wind power during the Arctic winter to pump water to the surface, where it will freeze more rapidly. We show that where appropriate devices are employed, it is possible to increase ice thickness above natural levels, by about 1 m over the course of the winter. We examine the effects this has in the Arctic climate, concluding that deployment over 10% of the Arctic, especially where ice survival is marginal, could more than reverse current trends of ice loss in the Arctic, using existing industrial capacity. We propose that winter ice thickening by wind-powered pumps be considered and assessed as part of a multipronged strategy for restoring sea ice and arresting the strongest feedbacks in the climate system.

  15. Some parameters in arctic sea ice dynamics from an expedition in the summer of 2003

    Institute of Scientific and Technical Information of China (English)

    LI Zhijun; ZHANG Zhanhai; LU Peng; DONG Xilu; CHENG Bin; CHEN Zhi

    2005-01-01

    On the basis of the investigated data for sea ice physical processes during the Second Chinese National Arctic Research Expedition (CHINARE-2003) in the summer of 2003, the sea ice dynamical characteristics were analyzed and the parameters describing these characteristics were given. The new findings discovered from these parameters are:(1) The ice concentration obtained from the investigation is two tenths to three tenths lower compared with that from the NOAA Ice Chart; and the ice thickness in the summer is 2 m less compared with the results obtained during the First Chinese National Arctic Research Expedition in 1999 (CHINARE-1999),(2) the standard deviation of the ice bottom fluctuation is 3.8 times that of the snow surface on the ice sheet; (3) the maximum speed of the ice floe on which camp CHIS7 is located (CHIS7 floe) is 1 300 m/h with rotation and oscillation. The rotation angle increased stepwise, the maximum being 37.8 ° , while the CHIS7 floe moved toward the north-east, and its rotation angle decreased stepwise.While the CHIS7 floe moved south-eastward. The oscillation period of CHIS7 floe is 12.45 h, which is consistent with that of the inertial current at the same latitude, showing the contribution of the inertial current to the ice floe movement.

  16. Arctic ice islands

    Energy Technology Data Exchange (ETDEWEB)

    Sackinger, W.M.; Jeffries, M.O.; Lu, M.C.; Li, F.C.

    1988-01-01

    The development of offshore oil and gas resources in the Arctic waters of Alaska requires offshore structures which successfully resist the lateral forces due to moving, drifting ice. Ice islands are floating, a tabular icebergs, up to 60 meters thick, of solid ice throughout their thickness. The ice islands are thus regarded as the strongest ice features in the Arctic; fixed offshore structures which can directly withstand the impact of ice islands are possible but in some locations may be so expensive as to make oilfield development uneconomic. The resolution of the ice island problem requires two research steps: (1) calculation of the probability of interaction between an ice island and an offshore structure in a given region; and (2) if the probability if sufficiently large, then the study of possible interactions between ice island and structure, to discover mitigative measures to deal with the moving ice island. The ice island research conducted during the 1983-1988 interval, which is summarized in this report, was concerned with the first step. Monte Carlo simulations of ice island generation and movement suggest that ice island lifetimes range from 0 to 70 years, and that 85% of the lifetimes are less then 35 years. The simulation shows a mean value of 18 ice islands present at any time in the Arctic Ocean, with a 90% probability of less than 30 ice islands. At this time, approximately 34 ice islands are known, from observations, to exist in the Arctic Ocean, not including the 10-meter thick class of ice islands. Return interval plots from the simulation show that coastal zones of the Beaufort and Chukchi Seas, already leased for oil development, have ice island recurrences of 10 to 100 years. This implies that the ice island hazard must be considered thoroughly, and appropriate safety measures adopted, when offshore oil production plans are formulated for the Alaskan Arctic offshore. 132 refs., 161 figs., 17 tabs.

  17. Influences of Ice Crystal Number Concentrations and Habits on Arctic Mixed-Phase Cloud Dynamics

    Science.gov (United States)

    Komurcu, Muge

    2016-09-01

    Mixed-phase clouds are frequently present in the Arctic atmosphere, and strongly affect the surface energy budget. In this study, the influences of ice crystal number concentrations and crystal growth habits on the Arctic mixed-phase cloud microphysics and dynamics are investigated for internally and externally driven cloud systems using an eddy-resolving model. Separate simulations are performed with increasing ice concentrations and different ice crystal habits. It is found that the habit influence on cloud microphysics and dynamics is as pronounced as increasing the ice crystal concentrations for internally driven clouds and more dominant for externally driven clouds. Habit influence can lead to a 10 % reduction in surface incident longwave radiation flux. Sensitivity tests are performed to identify the interactions between processes affecting cloud dynamics that allow for persistent clouds (i.e., the radiative cooling at cloud top, ice precipitation stabilization at cloud-base). When cloud-base stabilization influences of ice precipitation are weak, cloud dynamics is more sensitive to radiative cooling. Additional sensitivity simulations are done with increasing surface latent and sensible heat fluxes to identify the influences of external forcing on cloud dynamics. It is found that the magnitude of cloud circulations for an externally driven cloud system with strong precipitation and weak surface fluxes is similar to a weakly precipitating, optically thick, internally driven cloud. For cloud systems with intense ice precipitation obtained through either increasing ice crystal concentrations or assuming ice crystal shapes that grow rapidly and fall fast, the cloud layer may collapse despite the moistening effect of surface fluxes.

  18. Skillful seasonal forecasts of Arctic sea ice retreat and advance dates in a dynamical forecast system

    Science.gov (United States)

    Sigmond, M.; Reader, M. C.; Flato, G. M.; Merryfield, W. J.; Tivy, A.

    2016-12-01

    The need for skillful seasonal forecasts of Arctic sea ice is rapidly increasing. Technology to perform such forecasts with coupled atmosphere-ocean-sea ice systems has only recently become available, with previous skill evaluations mainly limited to area-integrated quantities. Here we show, based on a large set of retrospective ensemble model forecasts, that a dynamical forecast system produces skillful seasonal forecasts of local sea ice retreat and advance dates - variables that are of great interest to a wide range of end users. Advance dates can generally be skillfully predicted at longer lead times ( 5 months on average) than retreat dates ( 3 months). The skill of retreat date forecasts mainly stems from persistence of initial sea ice anomalies, whereas advance date forecasts benefit from longer time scale and more predictable variability in ocean temperatures. These results suggest that further investments in the development of dynamical seasonal forecast systems may result in significant socioeconomic benefits.

  19. Arctic Sea Ice

    Science.gov (United States)

    Stroeve, J. C.; Fetterer, F.; Knowles, K.; Meier, W.; Serreze, M.; Arbetter, T.

    2004-12-01

    Of all the recent observed changes in the Arctic environment, the reduction of sea ice cover stands out most prominantly. Several independent analysis have established a trend in Arctic ice extent of -3% per decade from the late 1970s to the late 1990s, with a more pronounced trend in summer. The overall downward trend in ice cover is characterized by strong interannual variability, with a low September ice extent in one year typically followed by recovery the next September. Having two extreme minimum years, such as what was observed in 2002 and 2003 is unusual. 2004 marks the third year in a row of substantially below normal sea ice cover in the Arctic. Early summer 2004 appeared unusual in terms of ice extent, with May a record low for the satellite period (1979-present) and June also exhibiting below normal ice extent. August 2004 extent is below that of 2003 and large reductions in ice cover are observed once again off the coasts of Siberia and Alaska and the Greenland Sea. Neither the 2002 or 2003 anomaly appeared to be strongly linked to the positive phase of the Arctic Oscillation (AO) during the preceding winter. Similarly, the AO was negative during winter 2003/2004. In the previous AO framework of Rigor et al (2002), a positive winter AO implied preconditioning of the ice cover to extensive summer decay. In this hypothesis, the AO does not explain all aspects of the recent decline in Arctic ice cover, such as the extreme minima of 2002, 2003 and 2004. New analysis by Rigor and Wallace (2004) suggest that the very positive AO state from 1989-1995 can explain the recent sea ice minima in terms of changes in the Arctic surface wind field associated with the previous high AO state. However, it is also reasonable to expect that a general decrease in ice thickness accompanying warming would manifest itself as greater sensitivity of the ice pack to wind forcings and albedo feedbacks. The decrease in multiyear ice and attendant changes in ice thickness

  20. Loss of sea ice in the Arctic.

    Science.gov (United States)

    Perovich, Donald K; Richter-Menge, Jacqueline A

    2009-01-01

    The Arctic sea ice cover is in decline. The areal extent of the ice cover has been decreasing for the past few decades at an accelerating rate. Evidence also points to a decrease in sea ice thickness and a reduction in the amount of thicker perennial sea ice. A general global warming trend has made the ice cover more vulnerable to natural fluctuations in atmospheric and oceanic forcing. The observed reduction in Arctic sea ice is a consequence of both thermodynamic and dynamic processes, including such factors as preconditioning of the ice cover, overall warming trends, changes in cloud coverage, shifts in atmospheric circulation patterns, increased export of older ice out of the Arctic, advection of ocean heat from the Pacific and North Atlantic, enhanced solar heating of the ocean, and the ice-albedo feedback. The diminishing Arctic sea ice is creating social, political, economic, and ecological challenges.

  1. Migration phenology and seasonal fidelity of an Arctic marine predator in relation to sea ice dynamics.

    Science.gov (United States)

    Cherry, Seth G; Derocher, Andrew E; Thiemann, Gregory W; Lunn, Nicholas J

    2013-07-01

    Understanding how seasonal environmental conditions affect the timing and distribution of synchronized animal movement patterns is a central issue in animal ecology. Migration, a behavioural adaptation to seasonal environmental fluctuations, is a fundamental part of the life history of numerous species. However, global climate change can alter the spatiotemporal distribution of resources and thus affect the seasonal movement patterns of migratory animals. We examined sea ice dynamics relative to migration patterns and seasonal geographical fidelity of an Arctic marine predator, the polar bear (Ursus maritimus). Polar bear movement patterns were quantified using satellite-linked telemetry data collected from collars deployed between 1991-1997 and 2004-2009. We showed that specific sea ice characteristics can predict the timing of seasonal polar bear migration on and off terrestrial refugia. In addition, fidelity to specific onshore regions during the ice-free period was predicted by the spatial pattern of sea ice break-up but not by the timing of break-up. The timing of migration showed a trend towards earlier arrival of polar bears on shore and later departure from land, which has been driven by climate-induced declines in the availability of sea ice. Changes to the timing of migration have resulted in polar bears spending progressively longer periods of time on land without access to sea ice and their marine mammal prey. The links between increased atmospheric temperatures, sea ice dynamics, and the migratory behaviour of an ice-dependent species emphasizes the importance of quantifying and monitoring relationships between migratory wildlife and environmental cues that may be altered by climate change.

  2. Ice-Free Arctic Ocean?

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and researchers were unable to identify any natural processes that might slow the deicing of the Arctic. "What really makes the Arctic different…

  3. DRI Technical Program: Emerging Dynamics of the Marginal Ice Zone Ice, Ocean and Atmosphere Interactions in the Arctic Marginal Ice Zone. Year 3 Annual Report

    Science.gov (United States)

    2014-09-30

    and Atmosphere Interactions in the Arctic Marginal...ice mass balance buoys (IMBs), wave buoys (WBs), and Automatic Weather Stations (AWS) in the region north of Alaska. The now deployed arrays have a... Arctic Marginal Ice Zone. Year 3 Annual Report 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e

  4. Provenance analysis of central Arctic Ocean sediments: Implications for circum-Arctic ice sheet dynamics and ocean circulation during Late Pleistocene

    Science.gov (United States)

    Kaparulina, Ekaterina; Strand, Kari; Lunkka, Juha Pekka

    2016-09-01

    Mineralogical and geochemical data generated from the well referred shallow core 96/12-1pc on the Lomonosov Ridge, central Arctic Ocean was used to evaluate ice transport from the circum-Arctic sources and variability in sediment drainage and provenance changes. In this study heavy minerals in central Arctic sediments were used to determine those most prominent provenance areas and their changes related to the Late Pleistocene history of glaciations in the Arctic. Provenance changes were then used to infer variations in the paleoceanographic environment of the central Arctic Ocean, such as variations in the distribution of sea ice, icebergs controlled by the Arctic Ocean circulation. Four critical end-members including Victoria and Banks Islands, the Putorana Plateau, the Anabar Shield, and the Verkhoyansk Fold Belt were identified from the Amerasian and Eurasian source areas, and their proportional contributions were estimated in relation to Late Pleistocene ice sheet dynamics and ocean circulation. The results show changes in transport pathways and source areas within two examined transitions MIS6-5 and MIS4-3. The main source for material during MIS6-5 transition was Amerasian margin due to the high dolomite content in the studied section of sediments inferring strong Beaufort Gyre (BG) and Transpolar Drift (TPD) transport for this material. IRD material during late the MIS6 to 5 deglacial event was from terrigenous input through from the MacKenzie route Banks/Victoria Islands then transported as far as the Lomonosov Ridge area. The transition, MIS4-3 in comparison with MIS6-5, shows a clear shift in source areas, reflected in a different mineralogical composition of sediments, supplied from the Eurasian margin, such as the Anabar Shield, the Putorana Plateau and the Verkhoyansk Fold Belt during active decay of the Barents-Kara Ice Sheet presumable associated with an ice-dammed lake outburst then triggered by a strong TPD over the central Arctic. These two

  5. Arctic Ice Studies

    Science.gov (United States)

    1993-02-01

    jFigure 1. NIfS-7 SWr imagery frou 6 July 1983 portrays variat s i ie con.centra- tion across the experiental area Figure 2. Large floes in the East...and P. T. Shaw. Particle pathways in the and by European Community Commission contract CCE CLI-083 F. Gulf Stream. Bull. Am. Meteorol. Soc.. 66, 1106...New York: Academic Press, 1981. pp. 29-62. ice in the arctic," inProc. 4th Symp. Remote Sensing of En viron., 1281 R. T. Lowry, private communication

  6. Inorganic carbon dynamics of melt pond-covered first year sea ice in the Canadian Arctic

    Directory of Open Access Journals (Sweden)

    N.-X. Geilfus

    2014-05-01

    Full Text Available Melt pond formation is a common feature of the spring and summer Arctic sea ice. However, the role of the melt ponds formation and the impact of the sea ice melt on both the direction and size of CO2 flux between air and sea is still unknown. Here we describe the CO2-carbonate chemistry of melting sea ice, melt ponds and the underlying seawater associated with measurement of CO2 fluxes across first year landfast sea ice in the Resolute Passage, Nunavut, in June 2012. Early in the melt season, the increase of the ice temperature and the subsequent decrease of the bulk ice salinity promote a strong decrease of the total alkalinity (TA, total dissolved inorganic carbon (TCO2 and partial pressure of CO2 (pCO2 within the bulk sea ice and the brine. Later on, melt pond formation affects both the bulk sea ice and the brine system. As melt ponds are formed from melted snow the in situ melt pond pCO2 is low (36 μatm. The percolation of this low pCO2 melt water into the sea ice matrix dilutes the brine resulting in a strong decrease of the in situ brine pCO2 (to 20 μatm. As melt ponds reach equilibrium with the atmosphere, their in situ pCO2 increase (up to 380 μatm and the percolation of this high concentration pCO2 melt water increase the in situ brine pCO2 within the sea ice matrix. The low in situ pCO2 observed in brine and melt ponds results in CO2 fluxes of −0.04 to −5.4 mmol m–2 d–1. As melt ponds reach equilibrium with the atmosphere, the uptake becomes less significant. However, since melt ponds are continuously supplied by melt water their in situ pCO2 still remains low, promoting a continuous but moderate uptake of CO2 (~ −1mmol m–2 d–1. The potential uptake of atmospheric CO2 by melting sea ice during the Arctic summer has been estimated from 7 to 16 Tg of C ignoring the role of melt ponds. This additional uptake of CO2 associated to Arctic sea ice needs to be further explored and considered in the estimation of the Arctic

  7. Chronology and dynamics of the Amundsen Gulf Ice Stream in Arctic Canada during the last glacial-interglacial transition

    Science.gov (United States)

    Lakeman, T. R.; MacLean, B.; Blasco, S.; Bennett, R.; Hughes Clarke, J. E.

    2012-04-01

    An extensive ice stream of the Laurentide ice sheet occupied Amundsen Gulf during the Last Glacial Maximum. The grounded ice stream extended northwestward to the margin of the inner shelf in the Beaufort Sea and to a depth of 450 metres. This glacier was one of the largest ice streams to emanate into the Arctic Ocean during the last glaciation and, as such, exerted a primary influence on the dynamics of the northwest Laurentide Ice Sheet. Ice stream retreat from its maximum position began prior to 13,000 cal yr BP. The pattern of extensive sole marks or glacial flutings on the seabed and on the adjacent mainland and islands confirms the direction of flow was from southeast to northwest. In the Gulf these features are imprinted primarily on subglacial sediment deposits. The bathymetry of the Gulf and known extent of the ice stream on land indicates the ice was at least 700 m thick. A series of moraines at the mouth of the Gulf mark temporary positions of the retreating ice stream margin. Early stages of ice retreat may have been associated with meltwater discharge under the ice stream as evidenced by current erosion associated with some sole marks or glacial flutings. Melting at the leading edge of the ice stream resulted in calving of icebergs and the generation of keel-scour marks in the seabed. Retreat of the ice stream was relatively rapid as indicated by thin and spatially discontinuous deglacial glaciomarine sediment in the Gulf. Furthermore, an expansive database of deglacial radiocarbon ages from eastern Banks Island, western Victoria Island, and the adjacent Arctic mainland, indicates that the ice stream had retreated fully from the Gulf by 12,500 cal yr BP. The lack of Holocene sediment draping the sole marks or flutings, and outcrops of exposed bedrock and glaciomarine sediment indicate very low sedimentation rates since ice retreat. The thin veneer of recent fine sediment that has been deposited discontinuously on the seabed in the Gulf indicates little

  8. Effectively Communicating Information about Dynamically Changing Arctic Sea Ice to the Public through the Global Fiducials Program

    Science.gov (United States)

    Molnia, B. F.; Friesen, B.; Wilson, E.; Noble, S.

    2015-12-01

    On July 15, 2009, the National Academy of Sciences (NAS) released a report, Scientific Value of Arctic Sea Ice Imagery Derived Products, advocating public release of Arctic images derived from classified data. In the NAS press release that announced the release, report lead Stephanie Pfirman states "To prepare for a possibly ice-free Arctic and its subsequent effects on the environment, economy, and national security, it is critical to have accurate projections of changes over the next several decades." In the same release NAS President Ralph Cicerone states "We hope that these images are the first of many that could help scientists learn how the changing climate could impact the environment and our society." The same day, Secretary of the Interior Ken Salazar announced that the requested images had been released and were available to the public on a US Geological Survey Global Fiducials Program (GFP) Library website (http://gfl.usgs.gov). The website was developed by the USGS to provide public access to the images and to support environmental analysis of global climate-related science. In the statement describing the release titled, Information Derived from Classified Materials Will Aid Understanding of Changing Climate, Secretary Salazar states "We need the best data from all places if we are to meet the challenges that rising carbon emissions are creating. This information will be invaluable to scientists, researchers, and the public as we tackle climate change." Initially about 700 Arctic sea ice images were released. Six years later, the number exceeds 1,500. The GFP continues to facilitate the acquisition of new Arctic sea ice imagery from US National Imagery Systems. This example demonstrates how information about dynamically changing Arctic sea ice continues to be effectively communicated to the public by the GFP. In addition to Arctic sea ice imagery, the GFP has publicly released imagery time series of more than 125 other environmentally important

  9. Applying High Resolution Imagery to Understand the Role of Dynamics in the Diminishing Arctic Sea Ice Cover

    Science.gov (United States)

    2014-09-30

    melt and freeze onset dates. REFERENCES Hutchings, J. K., et al. (2014), Sea Ice Deformation in the Arctic from 2000-2010, Geophys. Res. Lett., under...Eos, Vol. 92, No. 7, pp. 53-54. Richter-Menge, J., and S. L. Farrell (2013), Arctic Sea Ice Conditions in Spring 2009 - 2013 Prior to Melt ...refereed] Richter-Menge, J., and S. L. Farrell (2013), Arctic Sea Ice Conditions in Spring 2009 - 2013 Prior to Melt , Geophys. Res. Lett., 40, 5888

  10. Inorganic carbon dynamics of melt pond-covered first year sea ice in the Canadian Arctic

    DEFF Research Database (Denmark)

    Geilfus, Nicolas-Xavier; Galley, R.J.; Crabeck, O.

    2014-01-01

    Melt pond formation is a common feature of the spring and summer Arctic sea ice. However, the role of the melt ponds formation and the impact of the sea ice melt on both the direction and size of CO2 flux between air and sea is still unknown. Here we describe the CO2-carbonate chemistry of melting...... sea ice, melt ponds and the underlying seawater associated with measurement of CO2 fluxes across first year landfast sea ice in the Resolute Passage, Nunavut, in June 2012. Early in the melt season, the increase of the ice temperature and the subsequent decrease of the bulk ice salinity promote...... a strong decrease of the total alkalinity (TA), total dissolved inorganic carbon (TCO2) and partial pressure of CO2 (pCO2) within the bulk sea ice and the brine. Later on, melt pond formation affects both the bulk sea ice and the brine system. As melt ponds are formed from melted snow the in situ melt pond...

  11. The Last Arctic Sea Ice Refuge

    Science.gov (United States)

    Pfirman, S. L.; Tremblay, B.; Newton, R.; Fowler, C.

    2010-12-01

    Summer sea ice may persist along the northern flank of Canada and Greenland for decades longer than the rest of the Arctic, raising the possibility of a naturally formed refugium for ice-associated species. Observations and models indicate that some ice in this region forms locally, while some is transported to the area by winds and ocean currents. Depending on future changes in melt patterns and sea ice transport rates, both the central Arctic and Siberian shelf seas may be sources of ice to the region. An international system of monitoring and management of the sea ice refuge, along with the ice source regions, has the potential to maintain viable habitat for ice-associated species, including polar bears, for decades into the future. Issues to consider in developing a strategy include: + the likely duration and extent of summer sea ice in this region based on observations, models and paleoenvironmental information + the extent and characteristics of the “ice shed” contributing sea ice to the refuge, including its dynamics, physical and biological characteristics as well as potential for contamination from local or long-range sources + likely assemblages of ice-associated species and their habitats + potential stressors such as transportation, tourism, resource extraction, contamination + policy, governance, and development issues including management strategies that could maintain the viability of the refuge.

  12. Mechanism of seasonal Arctic sea ice evolution and Arctic amplification

    OpenAIRE

    Kim, Kwang-Yul; Hamlington, Benjamin D.; Na, Hanna; Kim, Jinju

    2016-01-01

    Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the p...

  13. Variability of scaling time series in the Arctic sea-ice drift dynamics

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2010-02-01

    Full Text Available The motion of an individual ice floe in the Arctic Ocean was monitored at the Russian research station North Pole 35 established on the ice pack in 2008. The ice floe speed (V was found to be correlated with wind speed (v in main features, such as the positions of maxima and minima of V and v. However, the fine structure of the V-variation cannot be explained by the wind forcing alone. There were periods of time when the floe drift was affected by the interactions of ice floes between each other or by the periodical forcing due to either the Coriolis inertia effect or the tidal activity. These data were compared with the "waiting times" statistics that are the distributions of time intervals between subsequent, sufficiently strong changes in the kinetic energy of drifting ice floe. These distributions were measured in several time windows differing in the average wind speed and wind direction, and/or in the mechanical state of the ice pack. The distribution functions N (t>τ, where N is the number of successive events of energy change separated by the time interval t that exceeds τ, constructed in different time windows demonstrate fractal or a multifractal nature of the time series during motion in the consolidated ice pack but were truly random when the ice floe drifted in the highly fragmented sea ice. The latter result shows the existence of a relationship between the long-range mechanical interactions in the pack and long-term memory (time scaling behaviour of the sea-ice motion.

  14. Ice, Ocean and Atmosphere Interactions in the Arctic Marginal Ice Zone

    Science.gov (United States)

    2015-09-30

    release; distribution is unlimited. DRI TECHNICAL PROGRAM: Emerging Dynamics Of The Marginal Ice Zone Ice, Ocean and Atmosphere Interactions in the... Arctic Marginal Ice Zone Year 4 Annual Report Jeremy Wilkinson British Antarctic Survey phone: 44 (0)1223 221489 fax: 44 (0) 1223...global) scientific team in order to better understand the ocean , sea ice and atmosphere interaction within the marginal ice zone

  15. History of sea ice in the Arctic

    DEFF Research Database (Denmark)

    Polyak, Leonid; Alley, Richard B.; Andrews, John T.

    2010-01-01

    Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past. This inf...

  16. Modeling ocean and sea ice dynamics of the Canadian Arctic Archipelago: Aspects of forcing

    Science.gov (United States)

    Wekerle, Claudia; Wang, Qiang; Danilov, Sergey; Myers, Paul G.; Jung, Thomas; Schröter, Jens

    2013-04-01

    The Canadian Arctic Archipelago (CAA) is one of the main pathways for freshwater exiting the Arctic Ocean. Freshwater exported to the North Atlantic may influence the deep water formation in the Labrador Sea, and thus the meridional overturning circulation. Modeling ocean and sea ice conditions of the CAA is difficult because of narrow straits and complex coastlines. The Finite-Element Sea-ice Ocean circulation Model (FESOM) configured on a global mesh is applied to assess the volume, freshwater and sea ice transports through the CAA. With a mesh resolution of 5 km in the CAA we are able to accurately resolve complex coastlines. Outside the CAA the mesh is refined to 24 km north of 55°N with a global background resolution of 1.5°. In this study, first, it is shown that the transports modeled with FESOM correlate well with the available observational data. Second, the model is used to learn about the impact of different atmospheric forcing datasets differing in spatial and temporal resolution (CORE 2 and the Reforecast dataset from Environment Canada). The CORE 2 dataset is on the T62 grid, which is coarse compared to the Reforecast dataset with grid resolution of 0.45° longitude and 0.3° latitude. The temporal resolution of the Reforecast dataset is higher than the CORE 2 dataset (one hourly and 6-hourly data, respectively, for wind, surface temperature and specific humidity fields). The representation of sea ice in the CAA can be improved by using the high resolution atmospheric forcing.

  17. Arctic Sea Ice Predictability and the Sea Ice Prediction Network

    Science.gov (United States)

    Wiggins, H. V.; Stroeve, J. C.

    2014-12-01

    Drastic reductions in Arctic sea ice cover have increased the demand for Arctic sea ice predictions by a range of stakeholders, including local communities, resource managers, industry and the public. The science of sea-ice prediction has been challenged to keep up with these developments. Efforts such as the SEARCH Sea Ice Outlook (SIO; http://www.arcus.org/sipn/sea-ice-outlook) and the Sea Ice for Walrus Outlook have provided a forum for the international sea-ice prediction and observing community to explore and compare different approaches. The SIO, originally organized by the Study of Environmental Change (SEARCH), is now managed by the new Sea Ice Prediction Network (SIPN), which is building a collaborative network of scientists and stakeholders to improve arctic sea ice prediction. The SIO synthesizes predictions from a variety of methods, including heuristic and from a statistical and/or dynamical model. In a recent study, SIO data from 2008 to 2013 were analyzed. The analysis revealed that in some years the predictions were very successful, in other years they were not. Years that were anomalous compared to the long-term trend have proven more difficult to predict, regardless of which method was employed. This year, in response to feedback from users and contributors to the SIO, several enhancements have been made to the SIO reports. One is to encourage contributors to provide spatial probability maps of sea ice cover in September and the first day each location becomes ice-free; these are an example of subseasonal to seasonal, local-scale predictions. Another enhancement is a separate analysis of the modeling contributions. In the June 2014 SIO report, 10 of 28 outlooks were produced from models that explicitly simulate sea ice from dynamic-thermodynamic sea ice models. Half of the models included fully-coupled (atmosphere, ice, and ocean) models that additionally employ data assimilation. Both of these subsets (models and coupled models with data

  18. High resolution modelling of the decreasing Arctic sea ice

    DEFF Research Database (Denmark)

    Madsen, K. S.; Rasmussen, T. A. S.; Blüthgen, Jonas

    2012-01-01

    The Arctic sea ice cover has been rapidly decreasing and thinning over the last decade, with minimum ice extent in 2007 and almost as low extent in 2011. This study investigates two aspects of the decreasing ice cover; first the large scale thinning and changing dynamics of the polar sea ice......, and secondly oceanic oil drift in ice affected conditions. Both investigations are made with the coupled ocean - sea ice model HYCOM-CICE at 10 km resolution, which is also used operationally at DMI and allows detailed studies of sea ice build-up, drift and melt. To investigate the sea ice decrease of the last...... and changing dynamics and discuss how they relate to satellite observations. The relation to the upper ocean heat content is also investigated. The decreasing sea ice has opened up for increased ship traffic and oil exploration in the polar oceans. To avoid damage on the pristine Arctic ecosystem...

  19. Thin-ice Arctic Acoustic Window (THAAW)

    Science.gov (United States)

    2014-09-30

    STATEMENT A. Approved for public release; distribution is unlimited. Thin- ice Arctic Acoustic Window (THAAW) Peter F. Worcester Scripps Institution of...of the ice cover and extensive warming of the intermediate layers. The multiyear ice is melting . Ice keels are getting smaller. With more open water...determine the fundamental limits to signal processing in the Arctic imposed by ocean and ice processes. The hope is that these first few new steps will

  20. Stratospheric Impacts on Arctic Sea Ice

    Science.gov (United States)

    Reichler, Thomas

    2016-04-01

    Long-term circulation change in the stratosphere can have substantial effects on the oceans and their circulation. In this study we investigate whether and how sea ice at the ocean surface responds to intraseasonal stratospheric variability. Our main question is whether the surface impact of stratospheric sudden warmings (SSWs) is strong and long enough to affect sea ice. A related question is whether the increased frequency of SSWs during the 2000s contributed to the rapid decrease in Arctic sea ice during this time. To this end we analyze observations of sea ice, NCEP/NCAR reanalysis, and a long control integration with a stratospherically-enhanced version of the GFDL CM2.1 climate model. From both observations and the model we find that stratospheric extreme events have a demonstrable impact on the distribution of Arctic sea ice. The areas most affected are near the edge of the climatological ice line over the North Atlantic, North Pacific, and the Arctic Ocean. The absolute changes in sea ice coverage amount to +/-10 %. Areas and magnitudes of increase and decrease are about the same. It is thus unlikely that the increased SSW frequency during the 2000s contributed to the decline of sea ice during that period. The sea ice changes are consistent with the impacts of a negative NAO at the surface and can be understood in terms of (1) dynamical change due to altered surface wind stress and (2) thermodynamical change due to altered temperature advection. Both dynamical and thermodynamical change positively reinforce each other in producing sea change. A simple advection model is used to demonstrate that most of the sea ice change can be explained from the sea ice drift due to the anomalous surface wind stress. Changes in the production or melt of sea ice by thermodynamical effects are less important. Overall, this study adds to an increasing body of evidence that the stratosphere not only impacts weather and climate of the atmosphere but also the surface and

  1. Multiscale Models of Melting Arctic Sea Ice

    Science.gov (United States)

    2014-09-30

    1 Multiscale Models of Melting Arctic Sea Ice Kenneth M. Golden University of Utah, Department of Mathematics phone: (801) 581-6851...feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding the evolution of melt ponds and sea...Models of Melting Arctic Sea Ice 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER

  2. Sea ice thickness and recent Arctic warming

    Science.gov (United States)

    Lang, Andreas; Yang, Shuting; Kaas, Eigil

    2017-01-01

    The climatic impact of increased Arctic sea ice loss has received growing attention in the last years. However, little focus has been set on the role of sea ice thickness, although it strongly determines surface heat fluxes. Here ensembles of simulations using the EC-Earth atmospheric model (Integrated Forecast System) are performed and analyzed to quantify the atmospheric impacts of Arctic sea ice thickness change since 1982 as revealed by the sea ice model assimilation Global Ice-Ocean Modeling and Assimilation System. Results show that the recent sea ice thinning has significantly affected the Arctic climate, while remote atmospheric responses are less pronounced owing to a high internal atmospheric variability. Locally, the sea ice thinning results in enhancement of near-surface warming of about 1°C per decade in winter, which is most pronounced over marginal sea ice areas with thin ice. This leads to an increase of the Arctic amplification factor by 37%.

  3. Arctic Landfast Sea Ice 1953-1998

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The files in this data set contain landfast sea ice data (monthly means) gathered from both Russian Arctic and Antarctic Research Institute (AARI) and Canadian Ice...

  4. Total and methylated mercury in Arctic multiyear sea ice.

    Science.gov (United States)

    Beattie, Sarah A; Armstrong, Debbie; Chaulk, Amanda; Comte, Jérôme; Gosselin, Michel; Wang, Feiyue

    2014-05-20

    Mercury is one of the primary contaminants of concern in the Arctic marine ecosystem. While considerable efforts have been directed toward understanding mercury cycling in the Arctic, little is known about mercury dynamics within Arctic multiyear sea ice, which is being rapidly replaced with first-year ice. Here we report the first study on the distribution and potential methylation of mercury in Arctic multiyear sea ice. Based on three multiyear ice cores taken from the eastern Beaufort Sea and McClure Strait, total mercury concentrations ranged from 0.65 to 60.8 pM in bulk ice, with the highest values occurring in the topmost layer (∼40 cm) which is attributed to the dynamics of particulate matter. Methylated mercury concentrations ranged from below the method detection limit (ice, suggesting the potential occurrence of in situ mercury methylation. The annual fluxes of total and methylated mercury into the Arctic Ocean via melt of multiyear ice are estimated to be 420 and 42 kg yr(-1), respectively, representing an important and changing source of mercury and methylmercury into the Arctic Ocean marine ecosystem.

  5. Arctic Freshwater Ice and Its Climatic Role

    OpenAIRE

    Prowse, Terry; Alfredsen, Knut; Beltaos, Spyros; Bonsal, Barrie; Duguay, Claude; Korhola, Atte; McNamara, Jim; Vincent, Warwick F.; Vuglinsky, Valery; Weyhenmeyer, Gesa A.

    2011-01-01

    Freshwater ice dominates the Arctic terrestrial environment and significantly impacts bio-physical and socio-economic systems. Unlike other major cryospheric components that either blanket large expanses (e.g., snow, permafrost, sea ice) or are concentrated in specific locations, lake and river ice are interwoven into the terrestrial landscape through major flow and storage networks. For instance, the headwaters of large ice-covered rivers extend well beyond the Arctic while many northern lak...

  6. Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice

    Science.gov (United States)

    Assmy, Philipp; Fernández-Méndez, Mar; Duarte, Pedro; Meyer, Amelie; Randelhoff, Achim; Mundy, Christopher J.; Olsen, Lasse M.; Kauko, Hanna M.; Bailey, Allison; Chierici, Melissa; Cohen, Lana; Doulgeris, Anthony P.; Ehn, Jens K.; Fransson, Agneta; Gerland, Sebastian; Hop, Haakon; Hudson, Stephen R.; Hughes, Nick; Itkin, Polona; Johnsen, Geir; King, Jennifer A.; Koch, Boris P.; Koenig, Zoe; Kwasniewski, Slawomir; Laney, Samuel R.; Nicolaus, Marcel; Pavlov, Alexey K.; Polashenski, Christopher M.; Provost, Christine; Rösel, Anja; Sandbu, Marthe; Spreen, Gunnar; Smedsrud, Lars H.; Sundfjord, Arild; Taskjelle, Torbjørn; Tatarek, Agnieszka; Wiktor, Jozef; Wagner, Penelope M.; Wold, Anette; Steen, Harald; Granskog, Mats A.

    2017-01-01

    The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m-2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.

  7. Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice

    Science.gov (United States)

    Assmy, Philipp; Fernández-Méndez, Mar; Duarte, Pedro; Meyer, Amelie; Randelhoff, Achim; Mundy, Christopher J.; Olsen, Lasse M.; Kauko, Hanna M.; Bailey, Allison; Chierici, Melissa; Cohen, Lana; Doulgeris, Anthony P.; Ehn, Jens K.; Fransson, Agneta; Gerland, Sebastian; Hop, Haakon; Hudson, Stephen R.; Hughes, Nick; Itkin, Polona; Johnsen, Geir; King, Jennifer A.; Koch, Boris P.; Koenig, Zoe; Kwasniewski, Slawomir; Laney, Samuel R.; Nicolaus, Marcel; Pavlov, Alexey K.; Polashenski, Christopher M.; Provost, Christine; Rösel, Anja; Sandbu, Marthe; Spreen, Gunnar; Smedsrud, Lars H.; Sundfjord, Arild; Taskjelle, Torbjørn; Tatarek, Agnieszka; Wiktor, Jozef; Wagner, Penelope M.; Wold, Anette; Steen, Harald; Granskog, Mats A.

    2017-01-01

    The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean. PMID:28102329

  8. Arctic tides from GPS on sea ice

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing...... of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic. The GPS measurements are compared with the Arctic tidal model AOTIM-5, which assimilates tide...

  9. Links between ocean properties, ice cover, and plankton dynamics on interannual time scales in the Canadian Arctic Archipelago

    Science.gov (United States)

    Hamilton, James M.; Collins, Kate; Prinsenberg, Simon J.

    2013-10-01

    A decade of instrumented mooring data from Barrow Strait in the eastern Canadian Arctic Archipelago reveals connections between sea ice, water characteristics, and zooplankton dynamics on interannual time scales. On the North side of the Strait, the timing of breakup is positively related to the timing of freezeup in the previous year and negatively related to spring water temperature. This suggests that an early freezeup insulates the ocean from a cold autumn atmosphere, allowing heat to be retained until spring when it contributes to early sea ice erosion. There is also a very strong negative association between the timing of freezeup and late summer salinity, suggesting that monitoring of salinity in real time could be used to predict freezeup. A zooplankton biomass index derived from acoustic Doppler current profiler echo intensity data is used to demonstrate that on the North side there are also strong connections between early summer water temperature and the start, length, and productivity of the zooplankton growth season. On the South side of the Strait where currents are stronger, the relationships seen on the North side were not observed. But here integrated zooplankton biomass index and measured currents are used to identify interannual variability in the zooplankton biomass being delivered downstream into Lancaster Sound. Also on the South side, two yearlong records of daily fluorescence profiles reveal a large difference in the phytoplankton biomass being delivered downstream between years and demonstrate a strong relationship between the timing of the spring phytoplankton bloom and that of breakup.

  10. Age characteristics in a multidecadal Arctic sea ice simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hunke, Elizabeth C [Los Alamos National Laboratory; Bitz, Cecllia M [UNIV. OF WASHINGTON

    2008-01-01

    Results from adding a tracer for age of sea ice to a sophisticated sea ice model that is widely used for climate studies are presented. The consistent simulation of ice age, dynamics, and thermodynamics in the model shows explicitly that the loss of Arctic perennial ice has accelerated in the past three decades, as has been seen in satellite-derived observations. Our model shows that the September ice age average across the Northern Hemisphere varies from about 5 to 8 years, and the ice is much younger (about 2--3 years) in late winter because of the expansion of first-year ice. We find seasonal ice on average comprises about 5% of the total ice area in September, but as much as 1.34 x 10{sup 6} km{sup 2} survives in some years. Our simulated ice age in the late 1980s and early 1990s declined markedly in agreement with other studies. After this period of decline, the ice age began to recover, but in the final years of the simulation very little young ice remains after the melt season, a strong indication that the age of the pack will again decline in the future as older ice classes fail to be replenished. The Arctic ice pack has fluctuated between older and younger ice types over the past 30 years, while ice area, thickness, and volume all declined over the same period, with an apparent acceleration in the last decade.

  11. Ikaite crystal distribution in Arctic winter sea ice and implications for CO2 system dynamics

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Søgaard, D. H.; Cooper, M.

    2012-01-01

    concentration whereas TA concentrations in bottom layers were twice as high. This depth-related discrepancy suggests interior ice processes where ikaite crystals form in surface sea ice layers and partly dissolved in bottom layers. From these findings and model calculations we relate sea ice formation and melt......The precipitation of ikaite (CaCO3·6H2O) in polar sea ice is critical to the efficiency of the sea ice-driven carbon pump and potentially important to the global carbon cycle, yet the spatial and temporal occurrence of ikaite within the ice is poorly known. We report unique observations of ikaite...... in unmelted ice and vertical profiles of ikaite abundance and concentration in sea ice for the crucial season of winter. Ice was examined from two locations: a 1 m thick land-fast ice site and a 0.3 m thick polynya site, both in the Young Sound area (74° N, 20° W) of NE Greenland. Ikaite crystals, ranging...

  12. Mechanism of seasonal Arctic sea ice evolution and Arctic amplification

    Science.gov (United States)

    Kim, Kwang-Yul; Hamlington, Benjamin D.; Na, Hanna; Kim, Jinju

    2016-09-01

    Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents-Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.

  13. Predictability of the Arctic sea ice edge

    Science.gov (United States)

    Goessling, H. F.; Tietsche, S.; Day, J. J.; Hawkins, E.; Jung, T.

    2016-02-01

    Skillful sea ice forecasts from days to years ahead are becoming increasingly important for the operation and planning of human activities in the Arctic. Here we analyze the potential predictability of the Arctic sea ice edge in six climate models. We introduce the integrated ice-edge error (IIEE), a user-relevant verification metric defined as the area where the forecast and the "truth" disagree on the ice concentration being above or below 15%. The IIEE lends itself to decomposition into an absolute extent error, corresponding to the common sea ice extent error, and a misplacement error. We find that the often-neglected misplacement error makes up more than half of the climatological IIEE. In idealized forecast ensembles initialized on 1 July, the IIEE grows faster than the absolute extent error. This means that the Arctic sea ice edge is less predictable than sea ice extent, particularly in September, with implications for the potential skill of end-user relevant forecasts.

  14. Massive phytoplankton blooms under Arctic sea ice.

    Science.gov (United States)

    Arrigo, Kevin R; Perovich, Donald K; Pickart, Robert S; Brown, Zachary W; van Dijken, Gert L; Lowry, Kate E; Mills, Matthew M; Palmer, Molly A; Balch, William M; Bahr, Frank; Bates, Nicholas R; Benitez-Nelson, Claudia; Bowler, Bruce; Brownlee, Emily; Ehn, Jens K; Frey, Karen E; Garley, Rebecca; Laney, Samuel R; Lubelczyk, Laura; Mathis, Jeremy; Matsuoka, Atsushi; Mitchell, B Greg; Moore, G W K; Ortega-Retuerta, Eva; Pal, Sharmila; Polashenski, Chris M; Reynolds, Rick A; Schieber, Brian; Sosik, Heidi M; Stephens, Michael; Swift, James H

    2012-06-15

    Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.

  15. Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes

    Science.gov (United States)

    Arp, Christopher D.; Jones, Benjamin M.; Liljedahl, Anna K.; Hinkel, Kenneth M.; Welker, Jeffery A.

    2015-01-01

    Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since many Arctic lakes are shallow and ice grows thick (historically 2-m or greater), seasonal ice commonly freezes to the lake bed (bedfast ice) by winter's end. Bedfast ice fundamentally alters lake energy balance and melt-out processes compared to deeper lakes that exceed the maximum ice thickness (floating ice) and maintain perennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-out of bedfast ice lakes occurred on average 17 days earlier (22-June) than ice-out on adjacent floating ice lakes (9-July). Earlier ice-free conditions in bedfast ice lakes caused higher open-water evaporation, 28% on average, relative to floating ice lakes and this divergence increased in lakes closer to the coast and in cooler summers. Water isotopes (18O and 2H) indicated similar differences in evaporation between these lake types. Our analysis suggests that ice regimes created by the combination of lake depth relative to ice thickness and associated ice-out timing currently cause a strong hydrologic divergence among Arctic lakes. Thus understanding the distribution and dynamics of lakes by ice regime is essential for predicting regional hydrology. An observed regime shift in lakes to floating ice conditions due to thinner ice growth may initially offset lake drying because of lower evaporative loss from this lake type. This potential negative feedback caused by winter processes occurs in spite of an overall projected increase in evapotranspiration as the Arctic climate warms.

  16. The Arctic and Polar cells act on the Arctic sea ice variation

    Directory of Open Access Journals (Sweden)

    Weihong Qian

    2015-08-01

    Full Text Available The Arctic sea ice has undergone a substantial long-term decline with superimposed interannual sea ice minimum (SIM events over the last decades. This study focuses on the relationship between atmospheric circulation and the SIM events in the Arctic region. Four reanalysis products and simulations of one climate model are first analysed to confirm the existence of the Arctic cell, a meridional circulation cell to the north of 80°N, by visualising through the mean streamline and mean mass stream function in the Northern Hemisphere. Dynamical analyses of zonally averaged stationary eddy heat and momentum fluxes as well as the global precipitation rate data further confirm its existence. Finally, we found that the change in the Arctic sea ice concentration lags the variations of the descending air flow intensity associated with the Polar and Arctic cells, by about 2 months for the climatic annual cycle and about 10 months for the interannual anomaly. Five Arctic SIM events during the last three decades support this relationship. These results have implications for understanding the relationship between atmospheric circulation and sea-ice variations, and for predicting the Arctic sea ice changes.

  17. Sikuliqiruq: Ice dynamics of the Meade river - Arctic Alaska, from freezeup to breakup from time-series ground imagery

    Science.gov (United States)

    Beck, R.A.; Rettig, A.J.; Ivenso, C.; Eisner, Wendy R.; Hinkel, Kenneth M.; Jones, Benjamin M.; Arp, C.D.; Grosse, G.; Whiteman, D.

    2010-01-01

    Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery ofthe Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover ofthe Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23:47 UTC on 23 May 2009 and 01:27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was ofthe thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic. ?? 2010 Taylor & Francis.

  18. Albedo evolution of seasonal Arctic sea ice

    Science.gov (United States)

    Perovich, Donald K.; Polashenski, Christopher

    2012-04-01

    There is an ongoing shift in the Arctic sea ice cover from multiyear ice to seasonal ice. Here we examine the impact of this shift on sea ice albedo. Our analysis of observations from four years of field experiments indicates that seasonal ice undergoes an albedo evolution with seven phases; cold snow, melting snow, pond formation, pond drainage, pond evolution, open water, and freezeup. Once surface ice melt begins, seasonal ice albedos are consistently less than albedos for multiyear ice resulting in more solar heat absorbed in the ice and transmitted to the ocean. The shift from a multiyear to seasonal ice cover has significant implications for the heat and mass budget of the ice and for primary productivity in the upper ocean. There will be enhanced melting of the ice cover and an increase in the amount of sunlight available in the upper ocean.

  19. High resolution modelling of the decreasing Arctic sea ice

    DEFF Research Database (Denmark)

    Madsen, K. S.; Rasmussen, T. A. S.; Blüthgen, Jonas

    2012-01-01

    , and secondly oceanic oil drift in ice affected conditions. Both investigations are made with the coupled ocean - sea ice model HYCOM-CICE at 10 km resolution, which is also used operationally at DMI and allows detailed studies of sea ice build-up, drift and melt. To investigate the sea ice decrease of the last......The Arctic sea ice cover has been rapidly decreasing and thinning over the last decade, with minimum ice extent in 2007 and almost as low extent in 2011. This study investigates two aspects of the decreasing ice cover; first the large scale thinning and changing dynamics of the polar sea ice...... decade, we have performed a reanalysis simulation of the years 1990-2011, forced with ERA Interim atmospheric data. Thus, the simulation includes both the period before the recent sea ice decrease and the full period of decrease up till today. We will present our model results of the thinning...

  20. Arctic and Southern Ocean Sea Ice Concentrations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly sea ice concentration for Arctic (1901 to 1995) and Southern oceans (1973 to 1990) were digitized on a standard 1-degree grid (cylindrical projection) to...

  1. Development, sensitivity analysis, and uncertainty quantification of high-fidelity arctic sea ice models.

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Kara J.; Bochev, Pavel Blagoveston; Paskaleva, Biliana S.

    2010-09-01

    Arctic sea ice is an important component of the global climate system and due to feedback effects the Arctic ice cover is changing rapidly. Predictive mathematical models are of paramount importance for accurate estimates of the future ice trajectory. However, the sea ice components of Global Climate Models (GCMs) vary significantly in their prediction of the future state of Arctic sea ice and have generally underestimated the rate of decline in minimum sea ice extent seen over the past thirty years. One of the contributing factors to this variability is the sensitivity of the sea ice to model physical parameters. A new sea ice model that has the potential to improve sea ice predictions incorporates an anisotropic elastic-decohesive rheology and dynamics solved using the material-point method (MPM), which combines Lagrangian particles for advection with a background grid for gradient computations. We evaluate the variability of the Los Alamos National Laboratory CICE code and the MPM sea ice code for a single year simulation of the Arctic basin using consistent ocean and atmospheric forcing. Sensitivities of ice volume, ice area, ice extent, root mean square (RMS) ice speed, central Arctic ice thickness, and central Arctic ice speed with respect to ten different dynamic and thermodynamic parameters are evaluated both individually and in combination using the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA). We find similar responses for the two codes and some interesting seasonal variability in the strength of the parameters on the solution.

  2. Influence of sea ice on Arctic precipitation.

    Science.gov (United States)

    Kopec, Ben G; Feng, Xiahong; Michel, Fred A; Posmentier, Eric S

    2016-01-05

    Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess (d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture (or Arctic moisture proportion, AMP) is 18.2 ± 4.6% and 10.8 ± 3.6%/100,000 km(2) sea ice lost for each region, respectively, corresponding to increases of 10.9 ± 2.8% and 2.7 ± 1.1%/1 °C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions.

  3. Community dynamics of bottom-ice algae in Dease Strait of the Canadian Arctic

    Science.gov (United States)

    Campbell, K.; Mundy, C. J.; Landy, J. C.; Delaforge, A.; Michel, C.; Rysgaard, S.

    2016-12-01

    Sea ice algae are a characteristic feature in ice-covered seas, contributing a significant fraction of the total primary production in many areas and providing a concentrated food source of high nutritional value to grazers in the spring. Algae respond to physical changes in the sea ice environment by modifying their cellular carbon, nitrogen and pigment content, and by adjusting their photophysiological characteristics. In this study we examined how the ratios of particulate organic carbon (POC) to nitrogen (PON), and POC to chlorophyll a (chl a), responded to the evolving snow-covered sea ice environment near Cambridge Bay, Nunavut, during spring 2014. We also estimated photosynthesis-irradiance (PI) curves using oxygen-optodes and evaluated the resulting time-series of PI parameters under thin and thick snow-covered sites. There were no significant differences in PI parameters between samples from different overlying snow depths, and only the maximum photosynthetic rates in the absence of photoinhibition (PsB) and photoacclimation (IS) parameters changed significantly over the spring bloom. Furthermore, we found that both these parameters increased over time in response to increasing percent transmission of photosynthetically active radiation (TPAR) through the ice, indicating that light was a limiting factor of photosynthesis and was an important driver of temporal (over the spring) rather than spatial (between snow depths) variability in photophysiological response. However, we note that spatial variability in primary production was evident. Higher TPAR over the spring and under thin snow affected the composition of algae over both time and space, causing greater POC:chl a estimates in late spring and under thin snow cover. Nitrogen limitation was pronounced in this study, likely reducing PsB and algal photosynthetic rates, and increasing POC:PON ratios to over six times the Redfield average. Our results highlight the influence of both light and nutrients on

  4. Record Arctic Sea Ice Loss in 2007

    Science.gov (United States)

    2007-01-01

    This image of the Arctic was produced from sea ice observations collected by the Advanced Microwave Scanning Radiometer (AMSR-E) Instrument on NASA's Aqua satellite on September 16, overlaid on the NASA Blue Marble. The image captures ice conditions at the end of the melt season. Sea ice (white, image center) stretches across the Arctic Ocean from Greenland to Russia, but large areas of open water were apparent as well. In addition to record melt, the summer of 2007 brought an ice-free opening though the Northwest Passage that lasted several weeks. The Northeast Passage did not open during the summer of 2007, however, as a substantial tongue of ice remained in place north of the Russian coast. According to the National Snow and Ice Data Center (NSIDC), on September 16, 2007, sea ice extent dropped to 4.13 million square kilometers (1.59 million square miles)--38 percent below average and 24 percent below the 2005 record.

  5. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

    Science.gov (United States)

    2015-09-30

    the Arctic Ocean and surrounding seas, with particular emphasis on the Chukchi and Beaufort Seas. Some of the largest changes to the sea ice cover are...Changing Arctic Sea Ice Cover Don Perovich ERDC – CRREL 72 Lyme Road Hanover, NH 03755 Phone: 603-646-4255 Email: donald.k.perovich...quantitative understanding of the partitioning of solar radiation by the Arctic sea ice cover and its impact on the heat and mass balance of the ice and upper

  6. Light Absorption in Arctic Sea Ice - Black Carbon vs Chlorophyll

    Science.gov (United States)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Hunke, E. C.; Flanner, M.; Wang, H.; Dubey, M. K.; Jeffery, N.

    2015-12-01

    The fingerprint of climate change is more obvious in the Arctic than any other place on Earth. This is not only because the surface temperature there has increased at twice the rate of global mean temperature but also because Arctic sea ice extent has reached a record low of 49% reduction relative to the 1979-2000 climatology. Radiation absorption through black carbon (BC) deposited on Arctic snow and sea ice surface is one of the major hypothesized contributors to the decline. However, we note that chlorophyll-a absorption owing to increasing biology activity in this region could be a major competitor during boreal spring. Modeling of sea-ice physical and biological processes together with experiments and field observations promise rapid progress in the quality of Arctic ice predictions. Here we develop a dynamic ice system module to investigate discrete absorption of both BC and chlorophyll in the Arctic, using BC deposition fields from version 5 of Community Atmosphere Model (CAM5) and vertically distributed layers of chlorophyll concentrations from Sea Ice Model (CICE). To this point, our black carbon mixing ratios compare well with available in situ data. Both results are in the same order of magnitude. Estimates from our calculations show that sea ice and snow around the Canadian Arctic Archipelago and Baffin Bay has the least black carbon absorption while values at the ice-ocean perimeter in the region of the Barents Sea peak significantly. With regard to pigment concentrations, high amounts of chlorophyll are produced in Arctic sea ice by the bottom microbial community, and also within the columnar pack wherever substantial biological activity takes place in the presence of moderate light. We show that the percentage of photons absorbed by chlorophyll in the spring is comparable to the amount attributed to BC, especially in areas where the total deposition rates are decreasing with time on interannual timescale. We expect a continuous increase in

  7. Arctic sea ice and Eurasian climate: A review

    OpenAIRE

    Gao, Yongqi; Sun, Jianqi; Li, Fei; He, Shengping; SANDVEN, Stein; Yan, Qing; Zhang, Zhongshi; LOHMANN, Katja; KEENLYSIDE, Noel; Furevik, Tore; Suo, Lingling

    2014-01-01

    The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades, including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate. Paleo, obser...

  8. Observing the Arctic Ocean under melting ice - the UNDER-ICE project

    Science.gov (United States)

    Sagen, Hanne; Ullgren, Jenny; Geyer, Florian; Bergh, Jon; Hamre, Torill; Sandven, Stein; Beszczynska-Möller, Agnieszka; Falck, Eva; Gammelsrød, Tor; Worcester, Peter

    2014-05-01

    "standard" oceanographic measurements of current velocity and water mass properties will be deployed in the Fram Strait in September 2014. The dynamic processes in the marginal ice zone, in particular internal waves, mesoscale eddies, and front instabilities, will be explored using model experiments and high temporal resolution measurements. The results of the observational data analysis and model simulations will be integrated and compared with global climate model simulations (CMIP5). Satellite-derived data products will also be included in the synthesis. As part of the UNDER-ICE project, a web portal for Arctic data will be developed, that will offer open access to metadata and observational and model data products to support studies of Arctic climate and climate change.

  9. Floating Ice-Algal Aggregates below melting Arctic Sea Ice

    OpenAIRE

    Philipp Assmy; Jens K. Ehn; Mar Fernández-Méndez; Haakon Hop; Christian Katlein; Arild Sundfjord; Katrin Bluhm; Malin Daase; Anja Engel; Agneta Fransson; Granskog, Mats A.; Hudson, Stephen R.; Svein Kristiansen; Marcel Nicolaus; Ilka Peeken

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1 – 15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layer...

  10. Penicillium mycobiota in Arctic subglacial ice

    DEFF Research Database (Denmark)

    Sonjak, S.; Frisvad, Jens Christian; Gunde-Cimerman, N.

    2006-01-01

    to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L-1) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum......Fungi have been only rarely isolated from glacial ice in extremely cold polar regions and were in these cases considered as random, long-term preserved Aeolian deposits. Fungal presence has so far not been investigated in polar subglacial ice, a recently discovered extreme habitat reported......-rich ice....

  11. Arctic and Antarctic sea ice and climate

    Science.gov (United States)

    Barreira, S.

    2014-12-01

    Principal Components Analysis in T-Mode Varimax rotated was performed on Antarctic and Arctic monthly sea ice concentration anomalies (SICA) fields for the period 1979-2014, in order to investigate which are the main spatial characteristics of sea ice and its relationship with atmospheric circulation. This analysis provides 5 patterns of sea ice for inter-spring period and 3 patterns for summer-autumn for Antarctica (69,2% of the total variance) and 3 different patterns for summer-autumn and 3 for winter-spring season for the Arctic Ocean (67,8% of the total variance).Each of these patterns has a positive and negative phase. We used the Monthly Polar Gridded Sea Ice Concentrations database derived from satellite information generated by NASA Team algorithm. To understand the links between the SICA and climate trends, we extracted the mean pressure and, temperature field patterns for the months with high loadings (positive or negative) of the sea ice patterns that gave distinct atmospheric structures associated with each one. For Antarctica, the first SICA spatial winter-spring pattern in positive phase shows a negative SICA centre over the Drake Passage and north region of Bellingshausen and Weddell Seas together with another negative SICA centre over the East Indian Ocean. Strong positive centres over the rest of the Atlantic and Indian Oceans basins and the Amundsen Sea are also presented. A strong negative pressure anomaly covers most of the Antarctic Continent centered over the Bellingshausen Sea accompanied by three positive pressure anomalies in middle-latitudes. During recent years, the Arctic showed persistent associations of sea-ice and climate patterns principally during summer. Our strongest summer-autumn pattern in negative phase showed a marked reduction on SICA over western Arctic, primarily linked to an overall increase in Arctic atmospheric temperature most pronounced over the Beaufort, Chukchi and East Siberian Seas, and a positive anomaly of

  12. Floating ice-algal aggregates below melting arctic sea ice.

    Science.gov (United States)

    Assmy, Philipp; Ehn, Jens K; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A; Hudson, Stephen R; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H H; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.

  13. Multi-model seasonal forecast of Arctic sea-ice: forecast uncertainty at pan-Arctic and regional scales

    Science.gov (United States)

    Blanchard-Wrigglesworth, E.; Barthélemy, A.; Chevallier, M.; Cullather, R.; Fučkar, N.; Massonnet, F.; Posey, P.; Wang, W.; Zhang, J.; Ardilouze, C.; Bitz, C. M.; Vernieres, G.; Wallcraft, A.; Wang, M.

    2016-10-01

    Dynamical model forecasts in the Sea Ice Outlook (SIO) of September Arctic sea-ice extent over the last decade have shown lower skill than that found in both idealized model experiments and hindcasts of previous decades. Additionally, it is unclear how different model physics, initial conditions or forecast post-processing (bias correction) techniques contribute to SIO forecast uncertainty. In this work, we have produced a seasonal forecast of 2015 Arctic summer sea ice using SIO dynamical models initialized with identical sea-ice thickness in the central Arctic. Our goals are to calculate the relative contribution of model uncertainty and irreducible error growth to forecast uncertainty and assess the importance of post-processing, and to contrast pan-Arctic forecast uncertainty with regional forecast uncertainty. We find that prior to forecast post-processing, model uncertainty is the main contributor to forecast uncertainty, whereas after forecast post-processing forecast uncertainty is reduced overall, model uncertainty is reduced by an order of magnitude, and irreducible error growth becomes the main contributor to forecast uncertainty. While all models generally agree in their post-processed forecasts of September sea-ice volume and extent, this is not the case for sea-ice concentration. Additionally, forecast uncertainty of sea-ice thickness grows at a much higher rate along Arctic coastlines relative to the central Arctic ocean. Potential ways of offering spatial forecast information based on the timescale over which the forecast signal beats the noise are also explored.

  14. Multi-model seasonal forecast of Arctic sea-ice: forecast uncertainty at pan-Arctic and regional scales

    Science.gov (United States)

    Blanchard-Wrigglesworth, E.; Barthélemy, A.; Chevallier, M.; Cullather, R.; Fučkar, N.; Massonnet, F.; Posey, P.; Wang, W.; Zhang, J.; Ardilouze, C.; Bitz, C. M.; Vernieres, G.; Wallcraft, A.; Wang, M.

    2017-08-01

    Dynamical model forecasts in the Sea Ice Outlook (SIO) of September Arctic sea-ice extent over the last decade have shown lower skill than that found in both idealized model experiments and hindcasts of previous decades. Additionally, it is unclear how different model physics, initial conditions or forecast post-processing (bias correction) techniques contribute to SIO forecast uncertainty. In this work, we have produced a seasonal forecast of 2015 Arctic summer sea ice using SIO dynamical models initialized with identical sea-ice thickness in the central Arctic. Our goals are to calculate the relative contribution of model uncertainty and irreducible error growth to forecast uncertainty and assess the importance of post-processing, and to contrast pan-Arctic forecast uncertainty with regional forecast uncertainty. We find that prior to forecast post-processing, model uncertainty is the main contributor to forecast uncertainty, whereas after forecast post-processing forecast uncertainty is reduced overall, model uncertainty is reduced by an order of magnitude, and irreducible error growth becomes the main contributor to forecast uncertainty. While all models generally agree in their post-processed forecasts of September sea-ice volume and extent, this is not the case for sea-ice concentration. Additionally, forecast uncertainty of sea-ice thickness grows at a much higher rate along Arctic coastlines relative to the central Arctic ocean. Potential ways of offering spatial forecast information based on the timescale over which the forecast signal beats the noise are also explored.

  15. The progress in the study of Arctic pack ice ecology

    Institute of Scientific and Technical Information of China (English)

    何剑锋; 王桂忠; 蔡明红; 李少菁

    2004-01-01

    The sea ice community plays an important role in the Arctic marine ecosystem. Because of the predicted environmental changes in the Arctic environment and specifically related to sea ice, the Arctic pack ice biota has received more attention in recent years using modern ice-breaking research vessels. Studies show that the Arctic pack ice contains a diverse biota and besides ice algae, the bacterial and protozoan biomasses can be high. Surprisingly high primary production values were observed in the pack ice of the central Arctic Ocean. Occasionally biomass maximum were discovered in the interior of the ice floes, a habitat that had been ignored in most Arctic studies. Many scientific questions, which deserve special attention, remained unsolved due to logistic limitations and the sea ice characteristics. Little is know about the pack ice community in the central Arctic Ocean. Almost no data exists from the pack ice zone for the winter season. Concerning the abundance of bacteria and protozoa, more studies are needed to understand the microbial network within the ice and its role in material and energy flows. The response of the sea ice biota to global change will impact the entire Arctic marine ecosystem and a long-term monitoring program is needed. The techniques, that are applied to study the sea ice biota and the sea ice ecology, should be improved.

  16. The Arctic DP Research Project: Effective Stationkeeping in Ice

    Directory of Open Access Journals (Sweden)

    Roger Skjetne

    2014-10-01

    Full Text Available Stress on the environment from a potentially growing energy use is set to rise. Without doubt the energy resources in Arctic regions will be developed. An important goal will be to exploit the resources offered by for instance the Barents Sea as a new European energy province, and to do this in accordance with the principles of sustainable development that have successfully been used e.g. in the North Sea. The special edition of MIC on Arctic DP presents a set of articles that summarize to an extent the activities of the research project Arctic DP: Safe and green dynamic positioning operations of offshore vessels in an Arctic environment. This project was awarded in 2010 by the Research Council of Norway (RCN as a competence-building project (KMB project to NTNU and its partners Kongsberg Maritime, DNV GL, and Statoil. The objective was to target some of the challenges related to safe Arctic offshore operations by dynamic positioning. In this first article of the Arctic DP special edition we discuss the background for and establishment of the project, its planning and execution, and project closure. An overview is given for the scientific and engineering research performed in the project, with an account of what we have considered as Effective stationkeeping in ice by dynamic positioning. The corresponding research activities conducted under this main theme is summarized.

  17. Trends in sea-ice variability on the way to an ice-free Arctic

    CERN Document Server

    Bathiany, Sebastian; Williamson, Mark S; Lenton, Timothy M; Scheffer, Marten; van Nes, Egbert; Notz, Dirk

    2016-01-01

    It has been widely debated whether Arctic sea-ice loss can reach a tipping point beyond which a large sea-ice area disappears abruptly. The theory of dynamical systems predicts a slowing down when a system destabilises towards a tipping point. In simple stochastic systems this can result in increasing variance and autocorrelation, potentially yielding an early warning of an abrupt change. Here we aim to establish whether the loss of Arctic sea ice would follow these conceptual predictions, and which trends in sea ice variability can be expected from pre-industrial conditions toward an Arctic that is ice-free during the whole year. To this end, we apply a model hierarchy consisting of two box models and one comprehensive Earth system model. We find a consistent and robust decrease of the ice volume's annual relaxation time before summer ice is lost because thinner ice can adjust more quickly to perturbations. Thereafter, the relaxation time increases, mainly because the system becomes dominated by the ocean wa...

  18. Arctic ice cover, ice thickness and tipping points.

    Science.gov (United States)

    Wadhams, Peter

    2012-02-01

    We summarize the latest results on the rapid changes that are occurring to Arctic sea ice thickness and extent, the reasons for them, and the methods being used to monitor the changing ice thickness. Arctic sea ice extent had been shrinking at a relatively modest rate of 3-4% per decade (annually averaged) but after 1996 this speeded up to 10% per decade and in summer 2007 there was a massive collapse of ice extent to a new record minimum of only 4.1 million km(2). Thickness has been falling at a more rapid rate (43% in the 25 years from the early 1970s to late 1990s) with a specially rapid loss of mass from pressure ridges. The summer 2007 event may have arisen from an interaction between the long-term retreat and more rapid thinning rates. We review thickness monitoring techniques that show the greatest promise on different spatial and temporal scales, and for different purposes. We show results from some recent work from submarines, and speculate that the trends towards retreat and thinning will inevitably lead to an eventual loss of all ice in summer, which can be described as a 'tipping point' in that the former situation, of an Arctic covered with mainly multi-year ice, cannot be retrieved.

  19. Constraining projections of summer Arctic sea ice

    Directory of Open Access Journals (Sweden)

    F. Massonnet

    2012-11-01

    Full Text Available We examine the recent (1979–2010 and future (2011–2100 characteristics of the summer Arctic sea ice cover as simulated by 29 Earth system and general circulation models from the Coupled Model Intercomparison Project, phase 5 (CMIP5. As was the case with CMIP3, a large intermodel spread persists in the simulated summer sea ice losses over the 21st century for a given forcing scenario. The 1979–2010 sea ice extent, thickness distribution and volume characteristics of each CMIP5 model are discussed as potential constraints on the September sea ice extent (SSIE projections. Our results suggest first that the future changes in SSIE with respect to the 1979–2010 model SSIE are related in a complicated manner to the initial 1979–2010 sea ice model characteristics, due to the large diversity of the CMIP5 population: at a given time, some models are in an ice-free state while others are still on the track of ice loss. However, in phase plane plots (that do not consider the time as an independent variable, we show that the transition towards ice-free conditions is actually occurring in a very similar manner for all models. We also find that the year at which SSIE drops below a certain threshold is likely to be constrained by the present-day sea ice properties. In a second step, using several adequate 1979–2010 sea ice metrics, we effectively reduce the uncertainty as to when the Arctic could become nearly ice-free in summertime, the interval [2041, 2060] being our best estimate for a high climate forcing scenario.

  20. Fram Strait Spring Ice Export and September Arctic Sea Ice

    Science.gov (United States)

    Smedsrud, Lars H.; Halvorsen, Mari H.; Stroeve, Julienne; Zhang, Rong; Kloster, Kjell

    2016-04-01

    The Arctic Basin exports between 600 000 - 1 million km² of it's sea ice cover southwards through Fram Strait each year, comparing to about 10% of the ice covered area inside the basin. During winter ice export results in growth of new and relatively thin ice inside the basin, while during summer or spring export contributes directly to open water further north. A new updated time series from 1935 to 2014 of Fram Strait sea ice area export shows that the long-term annual mean export is about 880,000 km², with large annual and decadal variability and no long-term trend over the past 80 years. Nevertheless, the last decade has witnessed increased annual ice export, with several years having annual ice export exceed 1 million km². Evaluating the trend onwards from 1979, when satellite based sea ice coverage became more readily available, reveals an increase in annual export of about +6% per decade. This increase is caused by higher southward ice drift speeds due to stronger southward geostrophic winds, largely explained by increasing surface pressure over Greenland. Spring and summer area export increased more (+11% per decade) than in autumn and winter. Contrary to the last decade the 1950 - 1970 period had low export during spring and summer, and mid-September sea ice extent was consistently higher than both before and after these decades. We thus find that export anomalies during spring have a clear influence on the following September sea ice extent in general, and that for the recent decade the export may be partially responsible for the accelerating decline in Arctic sea ice extent.

  1. Halocarbons associated with Arctic sea ice

    OpenAIRE

    Atkinson, Helen M.; Hughes, Claire; Shaw, Marvin J.; Roscoe, Howard K.; Carpenter, Lucy J.; Liss, Peter S.

    2014-01-01

    Short-lived halocarbons were measured in Arctic sea-ice brine, seawater and air above the Greenland and Norwegian seas (∼81°N, 2 to 5°E) in mid-summer, from a melting ice floe at the edge of the ice pack. In the ice floe, concentrations of C2H5I, 2-C3H7I and CH2Br2 showed significant enhancement in the sea ice brine, of average factors of 1.7, 1.4 and 2.5 times respectively, compared to the water underneath and after normalising to brine volume. Concentrations of mono-iodocarbons in air are t...

  2. The missing Northern European winter cooling response to Arctic sea ice loss

    Science.gov (United States)

    Screen, James A.

    2017-03-01

    Reductions in Arctic sea ice may promote the negative phase of the North Atlantic Oscillation (NAO-). It has been argued that NAO-related variability can be used an as analogue to predict the effects of Arctic sea ice loss on mid-latitude weather. As NAO- events are associated with colder winters over Northern Europe, a negatively shifted NAO has been proposed as a dynamical pathway for Arctic sea ice loss to cause Northern European cooling. This study uses large-ensemble atmospheric simulations with prescribed ocean surface conditions to examine how seasonal-scale NAO- events are affected by Arctic sea ice loss. Despite an intensification of NAO- events, reflected by more prevalent easterly flow, sea ice loss does not lead to Northern European winter cooling and daily cold extremes actually decrease. The dynamical cooling from the changed NAO is `missing', because it is offset (or exceeded) by a thermodynamical effect owing to advection of warmer air masses.

  3. Arctic Sea Ice : Trends, Stability and Variability

    Science.gov (United States)

    Moon, W.; Wettlaufer, J. S.

    2014-12-01

    A stochastic Arctic sea-ice model is derived and analysed in detail to interpret the recent decay and associated variability of Arctic sea-ice under changes in radiative forcing. The approach begins from a deterministic model of the heat flux balance through the air/sea/ice system, which uses observed monthly-averaged heat fluxesto drive a time evolution of sea-ice thickness. This model reproduces the observed seasonal cycle of the ice cover and it is to this that stochastic noise--representing high frequency variability--is introduced.The model takes the form of a single periodic non-autonomous stochastic ordinary differential equation. The value of such a model is that it provides a relatively simple framework to examine the role of noise in the basic nonlinear interactions at play as transitions in the state of the ice cover (e.g., from perennial to seasonal) are approached. Moreover, the stability and the noise conspire to underlie the inter annual variability and how that variability changes as one approaches the deterministic bifurcations in the system.

  4. Thermodynamic and dynamic linkage between the inter-model spread of Arctic sea ice concentrations and Northern Hemisphere atmospheric and oceanic circulations in CMIP5 models

    Science.gov (United States)

    Cheung, Ho Nam; Keenlyside, Noel; Omrani, Nour-Eddine

    2017-04-01

    While all CMIP5 models simulate the decline of Arctic sea ice concentrations (SIC) in a warming climate, the magnitude of such changes has a large inter-model spread that contributes to the uncertainty of projected climate change. It is thus important to understand the underlying thermodynamic and dynamic causes of the inter-model spread. In this presentation, we will use the budget analysis to quantify how much the large-scale thermodynamic and dynamic factors contributes to the inter-model spread of SIC over the Arctic in the historical run of CMIP5 models. Our preliminary results show that the primary factor is the thermodynamic processes related to the Atlantic meridional overturning circulation, and the secondary factor is the wind-driven circulations related to the NAO and the Aleutian low. The dominant spatial patterns linking the inter-model spread of SIC and these factors could be obtained from the SVD analysis. We will also discuss the linkage between the inter-model spread of SIC and the large-scale circulation features over the Northern Hemisphere.

  5. Force balance and deformation characteristics of anisotropic Arctic sea ice (a high resolution study)

    Science.gov (United States)

    Feltham, D. L.; Heorton, H. D.; Tsamados, M.

    2016-12-01

    The spatial distribution of Arctic sea ice arises from its deformation, driven by external momentum forcing, thermodynamic growth and melt. The deformation of Arctic sea ice is observed to have structural alignment on a broad range of length scales. By considering the alignment of diamond-shaped sea ice floes, an anisotropic rheology (known as the Elastic Anisotropic Plastic, EAP, rheology) has been developed for use in a climate sea ice model. Here we present investigations into the role of anisotropy in determining the internal ice stress gradient and the complete force balance of Arctic sea ice using a state-of-the-art climate sea ice model. Our investigations are focused on the link between external imposed dynamical forcing, predominantly the wind stress, and the emergent properties of sea ice, including its drift speed and thickness distribution. We analyse the characteristics of deformation events for different sea ice states and anisotropic alignment over different regions of the Arctic Ocean. We present the full seasonal stress balance and sea ice state over the Arctic ocean. We have performed 10 km basin-scale simulations over a 30-year time scale, and 2 km and 500 m resolution simulations in an idealised configuration. The anisotropic EAP sea ice rheology gives higher shear stresses than the more customary isotropic EVP rheology, and these reduce ice drift speed and mechanical thickening, particularly important in the Archipelago. In the central Arctic the circulation of sea ice is reduced allowing it to grow thicker thermodynamically. The emergent stress-strain rate correlations from the EAP model suggest that it is possible to characterise the internal ice stresses of Arctic sea ice from observable basin-wide deformation and drift patterns.

  6. Arctic Sea Ice Decline - Results from Winter 2015/16

    OpenAIRE

    Nicolaus, Marcel; Hendricks, Stefan; Ricker, Robert

    2016-01-01

    Sea ice physicists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), are anticipating that the sea ice cover in the Arctic Ocean this summer may shrink to the record low of 2012. The scientists made this projection after evaluating current satellite data about the thickness of the ice cover. The data show that the arctic sea ice was already extraordinarily thin in the summer of 2015. Comparably little new ice formed during the past winter.

  7. Marine Transportation Implications of the Last Arctic Sea Ice Refuge

    Science.gov (United States)

    Brigham, L. W.

    2010-12-01

    Marine access is increasing throughout the Arctic Ocean and the 'Last Arctic Sea Ice Refuge' may have implications for governance and marine use in the region. Arctic marine transportation is increasing due to natural resource developemnt, increasing Arctic marine tourism, expanded Arctic marine research, and a general linkage of the Arctic to the gloabl economy. The Arctic Council recognized these changes with the release of the Arctic Marine Shipping Assessment of 2009. This key study (AMSA)can be viewed as a baseline assessment (using the 2004 AMSA database), a strategic guide for a host of stakeholders and actors, and as a policy document of the Arctic Council. The outcomes of AMSA of direct relevance to the Ice Refuge are within AMSA's 17 recommendations provided under three themes: Enhancing Arctic Marine Safety, Protecting Arctic People and the Environment, and Building the Arctic Marine Infrastructure. Selected recommendations of importance to the Ice Refuge include: a mandatory polar navigation code; identifying areas of heightened ecological and cultural significance; potential designation of special Arctic marine areas; enhancing the tracking and monitoring of Arctic marine traffic; improving circumpolar environmental response capacity; developing an Arctic search and rescue agreement; and, assessing the effects of marine transportation on marine mammals. A review will be made of the AMSA outcomes and how they can influence the governance, marine use, and future protection of this unique Arctic marine environment.

  8. Influence of Sea Ice on Arctic Marine Sulfur Biogeochemistry in the Community Climate System Model

    Energy Technology Data Exchange (ETDEWEB)

    Deal, Clara [Univ. of Alaska, Fairbanks, AL (United States); Jin, Meibing [Univ. of Alaska, Fairbanks, AL (United States)

    2013-06-30

    Global climate models (GCMs) have not effectively considered how responses of arctic marine ecosystems to a warming climate will influence the global climate system. A key response of arctic marine ecosystems that may substantially influence energy exchange in the Arctic is a change in dimethylsulfide (DMS) emissions, because DMS emissions influence cloud albedo. This response is closely tied to sea ice through its impacts on marine ecosystem carbon and sulfur cycling, and the ice-albedo feedback implicated in accelerated arctic warming. To reduce the uncertainty in predictions from coupled climate simulations, important model components of the climate system, such as feedbacks between arctic marine biogeochemistry and climate, need to be reasonably and realistically modeled. This research first involved model development to improve the representation of marine sulfur biogeochemistry simulations to understand/diagnose the control of sea-ice-related processes on the variability of DMS dynamics. This study will help build GCM predictions that quantify the relative current and possible future influences of arctic marine ecosystems on the global climate system. Our overall research objective was to improve arctic marine biogeochemistry in the Community Climate System Model (CCSM, now CESM). Working closely with the Climate Ocean Sea Ice Model (COSIM) team at Los Alamos National Laboratory (LANL), we added 1 sea-ice algae and arctic DMS production and related biogeochemistry to the global Parallel Ocean Program model (POP) coupled to the LANL sea ice model (CICE). Both CICE and POP are core components of CESM. Our specific research objectives were: 1) Develop a state-of-the-art ice-ocean DMS model for application in climate models, using observations to constrain the most crucial parameters; 2) Improve the global marine sulfur model used in CESM by including DMS biogeochemistry in the Arctic; and 3) Assess how sea ice influences DMS dynamics in the arctic marine

  9. How predictable is a summer-ice free Arctic?

    Science.gov (United States)

    Jahn, Alexandra

    2016-04-01

    There is large interest from different stakeholders in when we will first see a summer ice-free Arctic Ocean. However, while the CMIP5 models agree that we will see a further decline of the Arctic sea ice cover over the 21st century, their projections of when an ice-free Arctic will occur has a range of over 100 years for even the strongest forcing scenario, the RCP8.5. A large part of this uncertainty stems from model biases in the simulation of Arctic sea ice in some models. But apart from this bias, how predictable is the Arctic sea ice extent and the timing of the first ice-free Arctic summer in general? Using the Community Earth System Model (CESM) large ensemble with 40+ members for RCP8.5 and the CESM medium ensemble with 15 members for RCP4.5, we will show that internal variability leads to a range of ~20 years for predictions of threshold crossing of Arctic sea ice, limiting the long-term predictability of when an ice-free Arctic Ocean can first be expected. A detailed analysis of the trajectories of the individual ensemble members will reveal whether there are features of the climate system that allow an improvement of this predictability as we get closer to a summer ice-free Arctic.

  10. The seeding of ice algal blooms in Arctic pack ice: The multiyear ice seed repository hypothesis

    Science.gov (United States)

    Olsen, Lasse M.; Laney, Samuel R.; Duarte, Pedro; Kauko, Hanna M.; Fernández-Méndez, Mar; Mundy, Christopher J.; Rösel, Anja; Meyer, Amelie; Itkin, Polona; Cohen, Lana; Peeken, Ilka; Tatarek, Agnieszka; Róźańska-Pluta, Magdalena; Wiktor, Józef; Taskjelle, Torbjørn; Pavlov, Alexey K.; Hudson, Stephen R.; Granskog, Mats A.; Hop, Haakon; Assmy, Philipp

    2017-07-01

    During the Norwegian young sea ICE expedition (N-ICE2015) from January to June 2015 the pack ice in the Arctic Ocean north of Svalbard was studied during four drifts between 83° and 80°N. This pack ice consisted of a mix of second year, first year, and young ice. The physical properties and ice algal community composition was investigated in the three different ice types during the winter-spring-summer transition. Our results indicate that algae remaining in sea ice that survived the summer melt season are subsequently trapped in the upper layers of the ice column during winter and may function as an algal seed repository. Once the connectivity in the entire ice column is established, as a result of temperature-driven increase in ice porosity during spring, algae in the upper parts of the ice are able to migrate toward the bottom and initiate the ice algal spring bloom. Furthermore, this algal repository might seed the bloom in younger ice formed in adjacent leads. This mechanism was studied in detail for the dominant ice diatom Nitzschia frigida. The proposed seeding mechanism may be compromised due to the disappearance of older ice in the anticipated regime shift toward a seasonally ice-free Arctic Ocean.

  11. Canadian Ice Service Arctic Regional Sea Ice Charts in SIGRID-3 Format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Canadian Ice Service (CIS) produces digital Arctic regional sea ice charts for marine navigation, climate research, and input to the Global Digital Sea Ice Data...

  12. Diagnostic sea ice predictability in the pan-Arctic and U.S. Arctic regional seas

    Science.gov (United States)

    Cheng, Wei; Blanchard-Wrigglesworth, Edward; Bitz, Cecilia M.; Ladd, Carol; Stabeno, Phyllis J.

    2016-11-01

    This study assesses sea ice predictability in the pan-Arctic and U.S. Arctic regional (Bering, Chukchi, and Beaufort) seas with a purpose of understanding regional differences from the pan-Arctic perspective and how predictability might change under changing climate. Lagged correlation is derived using existing output from the Community Earth System Model Large Ensemble (CESM-LE), Pan-Arctic Ice-Ocean Modeling and Assimilation System, and NOAA Coupled Forecast System Reanalysis models. While qualitatively similar, quantitative differences exist in Arctic ice area lagged correlation in models with or without data assimilation. On regional scales, modeled ice area lagged correlations are strongly location and season dependent. A robust feature in the CESM-LE is that the pan-Arctic melt-to-freeze season ice area memory intensifies, whereas the freeze-to-melt season memory weakens as climate warms, but there are across-region variations in the sea ice predictability changes with changing climate.

  13. Mean Dynamic Topography of the Arctic Ocean

    Science.gov (United States)

    Farrell, Sinead Louise; Mcadoo, David C.; Laxon, Seymour W.; Zwally, H. Jay; Yi, Donghui; Ridout, Andy; Giles, Katherine

    2012-01-01

    ICESat and Envisat altimetry data provide measurements of the instantaneous sea surface height (SSH) across the Arctic Ocean, using lead and open water elevation within the sea ice pack. First, these data were used to derive two independent mean sea surface (MSS) models by stacking and averaging along-track SSH profiles gathered between 2003 and 2009. The ICESat and Envisat MSS data were combined to construct the high-resolution ICEn MSS. Second, we estimate the 5.5-year mean dynamic topography (MDT) of the Arctic Ocean by differencing the ICEn MSS with the new GOCO02S geoid model, derived from GRACE and GOCE gravity. Using these satellite-only data we map the major features of Arctic Ocean dynamical height that are consistent with in situ observations, including the topographical highs and lows of the Beaufort and Greenland Gyres, respectively. Smaller-scale MDT structures remain largely unresolved due to uncertainties in the geoid at short wavelengths.

  14. Sea ice, erosion, and vulnerability of Arctic coasts

    Science.gov (United States)

    Barnhart, Katherine; Overeem, Irina; Kay, Jennifer; Anderson, Robert

    2015-04-01

    Coasts form the dynamic interface between the terrestrial and oceanic systems. In the Arctic, and in much of the world, the coast is a zone of relatively high population, infrastructure, biodiversity, and ecosystem services. A significant difference between Arctic and temperate coasts is the presence of sea ice. Sea ice influences Arctic coasts in two main ways: (1) the length of the sea ice-free season controls the length of time over which nearshore water can interact with the land, and (2) the location of the sea ice edge controls the fetch over which storm winds can blow over open water, resulting in changes in nearshore water level and wave field. The resulting nearshore hydrodynamic environment impacts all aspects of the coastal system. We first combine satellite records of sea ice with a simple model for wind-driven storm surge and waves to estimate how changes in the length and character of the sea ice-free season have impacted the nearshore hydrodynamic environment along Alaska's Beaufort Sea Coast for the period 1979-2012. This region has experienced some of the greatest changes in both sea ice cover and coastal erosion rates in the Arctic and is anticipated to experience significant change in the future. The median length of the 2012 open-water season along this stretch of coast, in comparison to 1979, expanded by 1.9 x. At the same time, coastal erosion rates increased from 8.7 m yr-1 to 19 m yr-1. At Drew Point, winds from the northwest result in increased water levels at the coast and control the process of submarine notch incision, the rate-limiting step of coastal retreat. When open-water conditions exist, the distance to the sea ice edge exerts control on the water level and wave field through its control on fetch. We find that the extreme values of water-level setup at Drew Point have increased consistently with increasing fetch. We then extend our analysis of the length of the open water season to the entire Arctic using both satellite

  15. Windows in Arctic sea ice: Light transmission and ice algae in a refrozen lead

    Science.gov (United States)

    Kauko, Hanna M.; Taskjelle, Torbjørn; Assmy, Philipp; Pavlov, Alexey K.; Mundy, C. J.; Duarte, Pedro; Fernández-Méndez, Mar; Olsen, Lasse M.; Hudson, Stephen R.; Johnsen, Geir; Elliott, Ashley; Wang, Feiyue; Granskog, Mats A.

    2017-06-01

    The Arctic Ocean is rapidly changing from thicker multiyear to thinner first-year ice cover, with significant consequences for radiative transfer through the ice pack and light availability for algal growth. A thinner, more dynamic ice cover will possibly result in more frequent leads, covered by newly formed ice with little snow cover. We studied a refrozen lead (≤0.27 m ice) in drifting pack ice north of Svalbard (80.5-81.8°N) in May-June 2015 during the Norwegian young sea ICE expedition (N-ICE2015). We measured downwelling incident and ice-transmitted spectral irradiance, and colored dissolved organic matter (CDOM), particle absorption, ultraviolet (UV)-protecting mycosporine-like amino acids (MAAs), and chlorophyll a (Chl a) in melted sea ice samples. We found occasionally very high MAA concentrations (up to 39 mg m-3, mean 4.5 ± 7.8 mg m-3) and MAA to Chl a ratios (up to 6.3, mean 1.2 ± 1.3). Disagreement in modeled and observed transmittance in the UV range let us conclude that MAA signatures in CDOM absorption spectra may be artifacts due to osmotic shock during ice melting. Although observed PAR (photosynthetically active radiation) transmittance through the thin ice was significantly higher than that of the adjacent thicker ice with deep snow cover, ice algal standing stocks were low (≤2.31 mg Chl a m-2) and similar to the adjacent ice. Ice algal accumulation in the lead was possibly delayed by the low inoculum and the time needed for photoacclimation to the high-light environment. However, leads are important for phytoplankton growth by acting like windows into the water column.

  16. Multifractals, random walks and Arctic sea ice

    Science.gov (United States)

    Agarwal, Sahil; Wettlaufer, John

    We examine the long-term correlations and multifractal properties of daily satellite retrievals of Arctic sea ice albedo, extent, and ice velocity for decadal periods. The approach harnesses a recent development called Multifractal Temporally Weighted Detrended Fluctuation Analysis (MF-TWDFA), which exploits the intuition that points closer in time are more likely to be related than distant points. In both data sets we extract multiple crossover times, as characterized by generalized Hurst exponents, ranging from synoptic to decadal. The method goes beyond treatments that assume a single decay scale process, such as a first-order autoregression, which cannot be justifiably fit to these observations. The ice extent data exhibits white noise behavior from seasonal to bi-seasonal time scales, whereas the clear fingerprints of the short (weather) and long (~ 7 and 9 year) time scales remain, the latter associated with the recent decay in the ice cover. Thus, long term persistence is reentrant beyond the seasonal scale and it is not possible to distinguish whether a given ice extent minimum/maximum will be followed by a minimum/maximum that is larger or smaller in magnitude. The ice velocity data show long term persistence in auto covariance. NASA Grant NNH13ZDA001N-CRYO and Swedish Research Council Grant No. 638-2013-9243.

  17. Crystals and fabrics analysis of an Arctic thermal growth multi-year ice sample

    Institute of Scientific and Technical Information of China (English)

    李志军; 康建成; 张运良

    2002-01-01

    One of sea ice core samples was taken from Arctic by the First Chinese National Arctic Research Expedition Team in 1999. 20 vertical and 2 horizontal ice sections were cut out of the ice core sample 2.22 m in length, which covered the ice sheet from surface to bottom except losses for during sampling and section cutting. From the observation and analysis of the fabrics and crystals along the depth of the ice core sample, followings were found. Whole ice sheet consists of columnar, refrozen clastic pieces, granular, columnar, refrozen clastic pieces, granular, columnar and refrozen clastic pieces. This indicates that the ice core sample was 3-year old, and the ice sheet surface thawed and the melt water flowed into ice sheet during summer. Hence, the annual energy balance in Arctic can be determined by the ice sheet surface thawing in summer, and bottom growth in winter. The thickness of the ice sheet is kept constantly at a certain position based on the corresponding climate and ocean conditions; A new kind of hydrodynamic-effected ice crystal was found in the analysis and was defined as refrozen clastic pieces. The newly refrozen clastic pieces are explained as that they belong to the ocean dynamic broken ice pieces that come into contact with ice sheet due to buoyancy and move with the whole ice sheet. While these pieces moved to a colder zone, they were refrozen. Therefore, its structure is different from that of first-year ice and also can explain why there are typical Arctic sea ice micro-algae in the ice core sample. The age of the ice sheet is determined to be from 1997 winter to 1999 summer.

  18. Exploring Arctic Transpolar Drift During Dramatic Sea Ice Retreat

    DEFF Research Database (Denmark)

    Gascard, J.C.; Festy, J.; le Goff, H.

    2008-01-01

    The Arctic is undergoing significant environmental changes due to climate warming. The most evident signal of this warming is the shrinking and thinning of the ice cover of the Arctic Ocean. If the warming continues, as global climate models predict, the Arctic Ocean will change from a perennially...

  19. Can regional climate engineering save the summer Arctic sea ice?

    Science.gov (United States)

    Tilmes, S.; Jahn, Alexandra; Kay, Jennifer E.; Holland, Marika; Lamarque, Jean-Francois

    2014-02-01

    Rapid declines in summer Arctic sea ice extent are projected under high-forcing future climate scenarios. Regional Arctic climate engineering has been suggested as an emergency strategy to save the sea ice. Model simulations of idealized regional dimming experiments compared to a business-as-usual greenhouse gas emission simulation demonstrate the importance of both local and remote feedback mechanisms to the surface energy budget in high latitudes. With increasing artificial reduction in incoming shortwave radiation, the positive surface albedo feedback from Arctic sea ice loss is reduced. However, changes in Arctic clouds and the strongly increasing northward heat transport both counteract the direct dimming effects. A 4 times stronger local reduction in solar radiation compared to a global experiment is required to preserve summer Arctic sea ice area. Even with regional Arctic dimming, a reduction in the strength of the oceanic meridional overturning circulation and a shut down of Labrador Sea deep convection are possible.

  20. Characterization of sea-ice kinematic in the Arctic outflow region using buoy data

    Directory of Open Access Journals (Sweden)

    Ruibo Lei

    2016-01-01

    Full Text Available Data from four ice-tethered buoys deployed in 2010 were used to investigate sea-ice motion and deformation from the Central Arctic to Fram Strait. Seasonal and long-term changes in ice kinematics of the Arctic outflow region were further quantified using 42 ice-tethered buoys deployed between 1979 and 2011. Our results confirmed that the dynamic setting of the transpolar drift stream (TDS and Fram Strait shaped the motion of the sea ice. Ice drift was closely aligned with surface winds, except during quiescent conditions, or during short-term reversal of the wind direction opposing the TDS. Meridional ice velocity south of 85°N showed a distinct seasonal cycle, peaking between late autumn and early spring in agreement with the seasonality of surface winds. Inertia-induced ice motion was strengthened as ice concentration decreased in summer. As ice drifted southward into the Fram Strait, the meridional ice speed increased dramatically, while associated zonal ice convergence dominated the ice-field deformation. The Arctic atmospheric Dipole Anomaly (DA influenced ice drift by accelerating the meridional ice velocity. Ice trajectories exhibited less meandering during the positive phase of DA and vice versa. From 2005 onwards, the buoy data exhibit high Arctic sea-ice outflow rates, closely related to persistent positive DA anomaly. However, the long-term data from 1979 to 2011 do not show any statistically significant trend for sea-ice outflow, but exhibit high year-to-year variability, associated with the change in the polarity of DA.

  1. Impact of declining Arctic sea ice on winter snowfall

    OpenAIRE

    Liu, Jiping; Curry, Judith A.; Wang, Huijun; Song, Mirong; Radley M. Horton

    2012-01-01

    While the Arctic region has been warming strongly in recent decades, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and east Asia. Here we demonstrate that the decrease in autumn Arctic sea ice area is linked to changes in the winter Northern Hemisphere atmospheric circulation that have some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows mu...

  2. Current use pesticide and legacy organochlorine pesticide dynamics at the ocean-sea ice-atmosphere interface in resolute passage, Canadian Arctic, during winter-summer transition.

    Science.gov (United States)

    Pućko, Monika; Stern, Gary A; Burt, Alexis E; Jantunen, Liisa M; Bidleman, Terry F; Macdonald, Robie W; Barber, David G; Geilfus, Nicolas-X; Rysgaard, Søren

    2017-02-15

    Here, we present the first detailed analysis of processes by which various current use pesticides (CUPs) and legacy organochlorine pesticides (OCPs) are concentrated in melt ponds that form on Arctic sea ice in the summer, when surface snow is melting and ice eventually breaks up. Four current use pesticides (dacthal, chlorpyrifos, trifluralin, and pentachloronitrobenzene) and one legacy organochlorine pesticide (α-hexachlorocyclohexane) were detected in ponds in Resolute Passage, Canadian Arctic, in 2012. Melt-pond concentrations changed over time as a function of gas exchange, precipitation, and dilution with melting sea ice. Observed increases in melt-pond concentrations for all detected pesticides were associated with precipitation events. Dacthal reached the highest concentration of all current use pesticides in ponds (95±71pgL(-1)), a value exceeding measured concentrations in the under-ice (0m) and 5m seawater by >10 and >16 times, respectively. Drainage of dacthal-enriched pond water to the ocean during ice break-up provides an important ice-mediated annual delivery route, adding ~30% of inventory in the summer Mixed Layer (ML; 10m) in the Resolute Passage, and a concentrating mechanism with potential implications for exposures to organisms such as ice algae, and phytoplankton.

  3. Acoustic Monitoring of the Arctic Ice Cap

    Science.gov (United States)

    Porter, D. L.; Goemmer, S. A.; Chayes, D. N.

    2012-12-01

    Introduction The monitoring of the Arctic Ice Cap is important economically, tactically, and strategically. In the scenario of ice cap retreat, new paths of commerce open, e.g. waterways from Northern Europe to the Far East. Where ship-going commerce is conducted, the U.S. Navy and U.S. Coast Guard have always stood guard and been prepared to assist from acts of nature and of man. It is imperative that in addition to measuring the ice from satellites, e.g. Icesat, that we have an ability to measure the ice extent, its thickness, and roughness. These parameters play an important part in the modeling of the ice and the processes that control its growth or shrinking and its thickness. The proposed system consists of three subsystems. The first subsystem is an acoustic source, the second is an array of geophones and the third is a system to supply energy and transmit the results back to the analysis laboratory. The subsystems are described below. We conclude with a plan on how to tackle this project and the payoff to the ice cap modeler and hence the users, i.e. commerce and defense. System Two historically tested methods to generate a large amplitude multi-frequency sound source include explosives and air guns. A new method developed and tested by the University of Texas, ARL is a combustive Sound Source [Wilson, et al., 1995]. The combustive sound source is a submerged combustion chamber that is filled with the byproducts of the electrolysis of sea water, i.e. Hydrogen and Oxygen, an explosive mixture which is ignited via a spark. Thus, no additional compressors, gases, or explosives need to be transported to the Arctic to generate an acoustic pulse capable of the sediment and the ice. The second subsystem would be geophones capable of listening in the O(10 Hz) range and transmitting that data back to the laboratory. Thus two single arrays of geophones arranged orthogonal to each other with a range of 1000's of kilometers and a combustive sound source where the two

  4. Arctic sea ice concentration observed with SMOS during summer

    Science.gov (United States)

    Gabarro, Carolina; Martinez, Justino; Turiel, Antonio

    2017-04-01

    accelerated metamorphosis and melt processes during summer affecting the ice surface fraction measurements. Therefore, the SMOS SIC dataset has great potential during summer periods in which higher frequency radiometers present high uncertainties determining the SIC. This new dataset can contribute to complement ongoing monitoring efforts in the Arctic Cryosphere. [1] Comiso, J. C.: Large Decadal Decline of the Arctic Multiyear Ice Cover, Journal of Climate, 25, 1176-1193, 2012. [2] Holland, M. M. and Bitz, C. M.: Polar amplification of climate change in coupled models, Climate Dynamics, 21, 221-232, 2003. [3] Font, J, et al.: SMOS: The Challenging Sea Surface Salinity Measurement from Space'. Proc. IGARSS, no. 5, 649 -665, 2010. [4] Kerr, Y., et al.: The SMOS mission: New tool for monitoring key elements of the global water cycle Proc. IGARSS no. 5, 666-687, 2010. [5] Kaleschke, L., et al.: Sea ice thickness retrieval from SMOS brightness temperatures during the Arctic freeze-up period, Geophys. Res. Lett., doi:10.1029/ 2012GL050916, 2012. [6] Huntemann, et al.: Empirical sea ice thickness retrieval during the freeze up period from SMOS high incident angle observations, The Cryosphere Discuss., 7, 4379-4405, 2013.

  5. Sea ice occurrence predicts genetic isolation in the Arctic fox.

    Science.gov (United States)

    Geffen, Eli; Waidyaratne, Sitara; Dalén, Love; Angerbjörn, Anders; Vila, Carles; Hersteinsson, Pall; Fuglei, Eva; White, Paula A; Goltsman, Michael; Kapel, Christian M O; Wayne, Robert K

    2007-10-01

    Unlike Oceanic islands, the islands of the Arctic Sea are not completely isolated from migration by terrestrial vertebrates. The pack ice connects many Arctic Sea islands to the mainland during winter months. The Arctic fox (Alopex lagopus), which has a circumpolar distribution, populates numerous islands in the Arctic Sea. In this study, we used genetic data from 20 different populations, spanning the entire distribution of the Arctic fox, to identify barriers to dispersal. Specifically, we considered geographical distance, occurrence of sea ice, winter temperature, ecotype, and the presence of red fox and polar bear as nonexclusive factors that influence the dispersal behaviour of individuals. Using distance-based redundancy analysis and the BIOENV procedure, we showed that occurrence of sea ice is the key predictor and explained 40-60% of the genetic distance among populations. In addition, our analysis identified the Commander and Pribilof Islands Arctic populations as genetically unique suggesting they deserve special attention from a conservation perspective.

  6. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean.

    Science.gov (United States)

    Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-20

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (Arctic Ocean (79-90 °N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85 °N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  7. Late winter biogeochemical conditions under sea ice in the Canadian High Arctic

    Directory of Open Access Journals (Sweden)

    Helen S. Findlay

    2015-12-01

    Full Text Available With the Arctic summer sea-ice extent in decline, questions are arising as to how changes in sea-ice dynamics might affect biogeochemical cycling and phenomena such as carbon dioxide (CO2 uptake and ocean acidification. Recent field research in these areas has concentrated on biogeochemical and CO2 measurements during spring, summer or autumn, but there are few data for the winter or winter–spring transition, particularly in the High Arctic. Here, we present carbon and nutrient data within and under sea ice measured during the Catlin Arctic Survey, over 40 days in March and April 2010, off Ellef Ringnes Island (78° 43.11′ N, 104° 47.44′ W in the Canadian High Arctic. Results show relatively low surface water (1–10 m nitrate (<1.3 µM and total inorganic carbon concentrations (mean±SD=2015±5.83 µmol kg−1, total alkalinity (mean±SD=2134±11.09 µmol kg−1 and under-ice pCO2sw (mean±SD=286±17 µatm. These surprisingly low wintertime carbon and nutrient conditions suggest that the outer Canadian Arctic Archipelago region is nitrate-limited on account of sluggish mixing among the multi-year ice regions of the High Arctic, which could temper the potential of widespread under-ice and open-water phytoplankton blooms later in the season.

  8. Trajectories of arctic sea ice under anthropogenic warming scenarios

    Science.gov (United States)

    Zhang, J.; Steele, M.; Schweiger, A. J.

    2010-12-01

    A series of numerical experiments are conducted to study the possible trajectories of arctic sea ice in response to varying levels of future anthropogenic warming and climate variability using a sea ice-ocean model. A summer ice-free Arctic Ocean is likely by the mid-2040s if arctic surface air temperature (SAT) increases 4C by 2050 and climate variability is similar to the past relatively warm two decades. Summer ice volume decreases to very low levels (10-37% of the 1978-2009 summer mean) as early as 2025 and remains low in the following years, while summer ice extent continues to fluctuate annually. The rate of annual mean ice volume decrease relaxes approaching 2050. The causes of the reduced ice volume loss are examined.

  9. Export of Algal Biomass from the Melting Arctic Sea Ice

    OpenAIRE

    A. Boetius; S. Albrecht; Bakker, K; Bienhold, C.; J. Felden; Fernandez-Mendez, M; Hendricks, S.; C. Katlein; C Lalande; Krumpen, T.; M. Nicolaus; Peeken, I.; Rabe, B.; Rogacheva, A.; Rybakova, E.

    2013-01-01

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on ave...

  10. The Influence of Sea Ice on Arctic Low Cloud Properties and Radiative Effects

    Science.gov (United States)

    Taylor, Patrick C.

    2015-01-01

    The Arctic is one of the most climatically sensitive regions of the Earth. Climate models robustly project the Arctic to warm 2-3 times faster than the global mean surface temperature, termed polar warming amplification (PWA), but also display the widest range of surface temperature projections in this region. The response of the Arctic to increased CO2 modulates the response in tropical and extra-tropical regions through teleconnections in the atmospheric circulation. An increased frequency of extreme precipitation events in the northern mid-latitudes, for example, has been linked to the change in the background equator-to-pole temperature gradient implied by PWA. Understanding the Arctic climate system is therefore important for predicting global climate change. The ice albedo feedback is the primary mechanism driving PWA, however cloud and dynamical feedbacks significantly contribute. These feedback mechanisms, however, do not operate independently. How do clouds respond to variations in sea ice? This critical question is addressed by combining sea ice, cloud, and radiation observations from satellites, including CERES, CloudSAT, CALIPSO, MODIS, and microwave radiometers, to investigate sea ice-cloud interactions at the interannual timescale in the Arctic. Cloud characteristics are strongly tied to the atmospheric dynamic and thermodynamic state. Therefore, the sensitivity of Arctic cloud characteristics, vertical distribution and optical properties, to sea ice anomalies is computed within atmospheric dynamic and thermodynamic regimes. Results indicate that the cloud response to changes in sea ice concentration differs significantly between atmospheric state regimes. This suggests that (1) the atmospheric dynamic and thermodynamic characteristics and (2) the characteristics of the marginal ice zone are important for determining the seasonal forcing by cloud on sea ice variability.

  11. Export of algal biomass from the melting Arctic sea ice.

    Science.gov (United States)

    Boetius, Antje; Albrecht, Sebastian; Bakker, Karel; Bienhold, Christina; Felden, Janine; Fernández-Méndez, Mar; Hendricks, Stefan; Katlein, Christian; Lalande, Catherine; Krumpen, Thomas; Nicolaus, Marcel; Peeken, Ilka; Rabe, Benjamin; Rogacheva, Antonina; Rybakova, Elena; Somavilla, Raquel; Wenzhöfer, Frank

    2013-03-22

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average 9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function.

  12. Global Fiducials Program - Arctic Buoy Sea Ice Studies

    Science.gov (United States)

    Wilson, E. M.; Wilds, S. R.; Friesen, B. A.; Sloan, J. L.

    2012-12-01

    The U.S. Geological Survey has utilized remotely sensed imagery to analyze Arctic Sea Ice since 1997, and has collected and created thousands of Literal Image Derived Products (LIDPS) at one meter resolution for public distribution. From 1997-2012, six static sea ice sites located in the Arctic Basin were selected and added to the Global Fiducial Library (GFL), to create an annual series of geographically referenced images to allow scientists to study seasonal changes in Arctic ice. In early 2009, a scientific group known as MEDEA (Measurements of Earth Data for Environmental Analysis) requested additional collections to track ice floe movements during the course of an entire summer (April through September), to better understand seasonal changes in the Arctic Sea Ice. In order to track and capture the same ice cover over time, USGS adopted a methodology to utilize buoys deployed at various locations across the Arctic by the International Arctic Buoy Program. The data buoys record and transmit hourly GPS positions, along with meteorologic and climatologic data associated with the sea ice in which they are anchored. Repeated imaging of the ice cover is guided by the data buoy GPS to help estimate travel direction and speed of the ice cover. Imagery is referenced by the MEDEA scientists to study ice fracture patterns, sea ice ridge heights, ice cover percentages, seasonal development and coverage of melt ponds, evolution of ice concentrations, floe size distribution, lateral melting, and other variables that are used for input to refine and develop climate models. These same ice floe images have been added to the GFL for various buoy locations from 2009 through 2011, and are being acquired for the 2012 summer season.

  13. Retention of ice-associated amphipods: possible consequences for an ice-free Arctic Ocean.

    Science.gov (United States)

    Berge, J; Varpe, O; Moline, M A; Wold, A; Renaud, P E; Daase, M; Falk-Petersen, S

    2012-12-23

    Recent studies predict that the Arctic Ocean will have ice-free summers within the next 30 years. This poses a significant challenge for the marine organisms associated with the Arctic sea ice, such as marine mammals and, not least, the ice-associated crustaceans generally considered to spend their entire life on the underside of the Arctic sea ice. Based upon unique samples collected within the Arctic Ocean during the polar night, we provide a new conceptual understanding of an intimate connection between these under-ice crustaceans and the deep Arctic Ocean currents. We suggest that downwards vertical migrations, followed by polewards transport in deep ocean currents, are an adaptive trait of ice fauna that both increases survival during ice-free periods of the year and enables re-colonization of sea ice when they ascend within the Arctic Ocean. From an evolutionary perspective, this may have been an adaptation allowing success in a seasonally ice-covered Arctic. Our findings may ultimately change the perception of ice fauna as a biota imminently threatened by the predicted disappearance of perennial sea ice.

  14. Export of algal biomass from the melting Arctic Sea ice

    NARCIS (Netherlands)

    Boetius, A.; Albrecht, S.; Bakker, K.; Bienhold, C.; Felden, J.; Fernández-Méndez, M.; Hendricks, S.; Katlein, C.; Lalande, C.; Krumpen, T.; Nicolaus, M.; Peeken, I.; Rabe, B.; Rogacheva, A.; Rybakova, E.; Somavilla, R.; Wenzhöfer, F.; Shipboard Science Party

    2013-01-01

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central

  15. Export of algal biomass from the melting Arctic Sea ice

    NARCIS (Netherlands)

    Boetius, A.; Albrecht, S.; Bakker, K.; Bienhold, C.; Felden, J.; Fernández-Méndez, M.; Hendricks, S.; Katlein, C.; Lalande, C.; Krumpen, T.; Nicolaus, M.; Peeken, I.; Rabe, B.; Rogacheva, A.; Rybakova, E.; Somavilla, R.; Wenzhöfer, F.; Shipboard Science Party

    2013-01-01

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central

  16. New IceTracker Tool Depicts Forward and Backward Arctic Sea Ice Trajectories

    Science.gov (United States)

    Pfirman, S. L.; Campbell, G.; Tremblay, B.; Newton, R.; Meier, W.

    2013-12-01

    The IceTracker allows researchers, educators and the public to depict the forward drift trajectories of sea ice, as well as back trajectories showing the path the ice took to the specified location. Users enter in the location and date of an ice parcel - or parcels -- of interest, then select a later or earlier date, depending on whether they want to see the forward or the backward trajectory. The database for the IceTracker contains ice motion vectors based upon a pattern recognition algorithm applied to images of sea ice derived from microwave satellite data. Ice motion vector plots are single day motion estimates. The available database starts November 1978 and runs to the present with ca. 1 month delay. IceTracker output includes both an image of the ice motion path as well as a data file that has quasi-daily date, latitude, longitude, estimated sea ice age, ice drift speed, mean air temperature, and water depth. One can overlay different days on the same plot in different colors for comparing different seasons. This presentation highlights research, education, and outreach applications of the tool. Research applications include estimating the origin and melt location of sediment and contaminants sampled on or in sea ice, assessing potential trajectories oil spilled in ice-infested waters, documenting seasonal and interannual variability in ice drift trajectories from specific locations, defining the typical origins of ice that tend to melt in an area of interest, such as a polynya, and assessing the deviation from drift of polar bear foraging. The IceTracker can also be used in the social sciences, for example recreating Nansen's historic 1893-1896 trans-Arctic drift with the Fram under modern conditions and considering the implications of alternative fates. Educational purposes include teaching students about ice dynamics and interannual variability by setting up team competitions to be the first to reach the North Pole or some other location. Applications

  17. The potential transport of pollutants by Arctic sea ice

    OpenAIRE

    Pfirman, S. L.; Eicken, H.; Bauch, Dorothea; Weeks, W. F.

    1995-01-01

    Drifting sea ice in the Arctic may transport contaminants from coastal areas across the pole and release them during melting far from the source areas. Arctic sea ice often contains sediments entrained on the Siberian shelves and receives atmospheric deposition from Arctic haze. Elevated levels of some heavy metals (e.g. lead, iron, copper and cadmium) and organochlorines (e.g. PCBs and DDTs) have been observed in ice sampled in the Siberian seas, north of Svalbard, and in Baffin Bay. In orde...

  18. Nonlinear threshold behavior during the loss of Arctic sea ice.

    Science.gov (United States)

    Eisenman, I; Wettlaufer, J S

    2009-01-06

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice-albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.

  19. Decadal to seasonal variability of Arctic sea ice albedo

    Science.gov (United States)

    Agarwal, S.; Moon, W.; Wettlaufer, J. S.

    2011-10-01

    A controlling factor in the seasonal and climatological evolution of the sea ice cover is its albedo α. Here we analyze Arctic data from the Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder and assess the seasonality and variability of broadband albedo from a 23 year daily record. We produce a histogram of daily albedo over ice covered regions in which the principal albedo transitions are seen; high albedo in late winter and spring, the onset of snowmelt and melt pond formation in the summer, and fall freezeup. The bimodal late summer distribution demonstrates the combination of the poleward progression of the onset of melt with the coexistence of perennial bare ice with melt ponds and open water, which then merge to a broad peak at α $\\gtrsim$ 0.5. We find the interannual variability to be dominated by the low end of the α distribution, highlighting the controlling influence of the ice thickness distribution and large-scale ice edge dynamics. The statistics obtained provide a simple framework for model studies of albedo parameterizations and sensitivities.

  20. Decadal to seasonal variability of Arctic sea ice albedo

    CERN Document Server

    Agarwal, S; Wettlaufer, J S

    2011-01-01

    A controlling factor in the seasonal and climatological evolution of the sea ice cover is its albedo $\\alpha$. Here we analyze Arctic data from the Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder and assess the seasonality and variability of broadband albedo from a 23 year daily record. We produce a histogram of daily albedo over ice covered regions in which the principal albedo transitions are seen; high albedo in late winter and spring, the onset of snow melt and melt pond formation in the summer, and fall freeze up. The bimodal late summer distribution demonstrates the combination of the poleward progression of the onset of melt with the coexistence of perennial bare ice with melt ponds and open water, which then merge to a broad peak at $\\alpha \\gtrsim $ 0.5. We find the interannual variability to be dominated by the low end of the $\\alpha$ distribution, highlighting the controlling influence of the ice thickness distribution and large-scale ice edge dynamics. The statistics obtained pro...

  1. Modeling the seasonal variability of a coupled Arctic ice-ocean system

    Science.gov (United States)

    Hakkinen, Sirpa; Mellor, George L.

    1992-01-01

    The seasonal variability of the ice-ocean system in the Arctic Basin and the Norwegian, Greenland, and Barents Seas was modeled using a three-dimensional coupled ice-ocean model developed at Princeton University. The snow-ice model uses a three-level thermodynamic scheme similar to Semtner's (1976), but is extended to include the effect of leads. It is shown that simulations using the climatological monthly forcing fields produce a realistic seasonal variability of the ice cover. The ice thickness had a considerable sensitivity to the choice of the long-wave back radiation scheme, but these effects can be reduced through dynamical factors.

  2. Evaluation of Arctic Sea Ice Thickness Simulated by Arctic Ocean Model Intercomparison Project Models

    Science.gov (United States)

    Johnson, Mark; Proshuntinsky, Andrew; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nikolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; De Cuevas, Beverly

    2012-01-01

    Six Arctic Ocean Model Intercomparison Project model simulations are compared with estimates of sea ice thickness derived from pan-Arctic satellite freeboard measurements (2004-2008); airborne electromagnetic measurements (2001-2009); ice draft data from moored instruments in Fram Strait, the Greenland Sea, and the Beaufort Sea (1992-2008) and from submarines (1975-2000); and drill hole data from the Arctic basin, Laptev, and East Siberian marginal seas (1982-1986) and coastal stations (1998-2009). Despite an assessment of six models that differ in numerical methods, resolution, domain, forcing, and boundary conditions, the models generally overestimate the thickness of measured ice thinner than approximately 2 mand underestimate the thickness of ice measured thicker than about approximately 2m. In the regions of flat immobile landfast ice (shallow Siberian Seas with depths less than 25-30 m), the models generally overestimate both the total observed sea ice thickness and rates of September and October ice growth from observations by more than 4 times and more than one standard deviation, respectively. The models do not reproduce conditions of fast ice formation and growth. Instead, the modeled fast ice is replaced with pack ice which drifts, generating ridges of increasing ice thickness, in addition to thermodynamic ice growth. Considering all observational data sets, the better correlations and smaller differences from observations are from the Estimating the Circulation and Climate of the Ocean, Phase II and Pan-Arctic Ice Ocean Modeling and Assimilation System models.

  3. Arctic autumn sea ice decline and Asian winter temperature anomaly

    Institute of Scientific and Technical Information of China (English)

    LIU Na; LIN Lina; WANG Yingjie; KONG Bin; ZHANG Zhanhai; CHEN Hongxia

    2016-01-01

    Associations between the autumn Arctic sea ice concentration (SIC) and Asian winter temperature are discussed using the singular value decomposition analysis. Results show that in recent 33 years reduced autumn Arctic sea ice is accompanied by Asian winter temperature decrease except in the Tibetan plateau and the Arctic Ocean and the North Pacific Ocean coast. The autumn SIC reduction excites two geopotential height centers in Eurasia and the north Arctic Ocean, which are persistent from autumn to winter. The negative center is in Barents Sea/Kara Sea. The positive center is located in Mongolia. The anomalous winds are associated with geopotential height centers, providing favorable clod air for the Asian winter temperature decreasing in recent 33 years. This relationship indicates a potential long-term outlook for the Asian winter temperature decrease as the decline of the autumn sea ice in the Arctic Ocean is expected to continue as climate warms.

  4. Poleward eddy heat flux anomalies associated with recent Arctic sea ice loss

    Science.gov (United States)

    Hoshi, Kazuhira; Ukita, Jinro; Honda, Meiji; Iwamoto, Katsushi; Nakamura, Tetsu; Yamazaki, Koji; Dethloff, Klaus; Jaiser, Ralf; Handorf, Dörthe

    2017-01-01

    Details of the characteristics of upward planetary wave propagation associated with Arctic sea ice loss under present climate conditions are examined using reanalysis data and simulation results. Recent Arctic sea ice loss results in increased stratospheric poleward eddy heat fluxes in the eastern and central Eurasia regions and enhanced upward propagation of planetary-scale waves in the stratosphere. A linear decomposition scheme reveals that this modulation of the planetary waves arises from coupling of the climatological planetary wavefield with temperature anomalies for the eastern Eurasia region and with meridional wind anomalies for the central Eurasia region. Propagation of stationary Rossby wave packets results in a dynamic link between these temperature and meridional wind anomalies with sea ice loss over the Barents-Kara Sea. The results provide strong evidence that recent Arctic sea ice loss significantly modulates atmospheric circulation in winter to modify poleward eddy heat fluxes so as to drive stratosphere-troposphere coupling processes.

  5. Weakening of the Stratospheric Polar Vortex by Arctic Sea-Ice Loss

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

    2014-09-02

    Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea ice, the mechanism that links sea ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhance the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January- February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

  6. Nonlinear threshold behavior during the loss of Arctic sea ice

    CERN Document Server

    Eisenman, I; 10.1073/pnas.0806887106

    2008-01-01

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that while the ice-albedo feedback promotes the existence of multiple ice cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice-covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a ...

  7. Global warming releases microplastic legacy frozen in Arctic Sea ice

    National Research Council Canada - National Science Library

    Obbard, Rachel W; Sadri, Saeed; Wong, Ying Qi; Khitun, Alexandra A; Baker, Ian; Thompson, Richard C

    2014-01-01

    .... Here we show that Arctic Sea ice from remote locations contains concentrations of microplastics at least two orders of magnitude greater than those that have been previously reported in highly...

  8. Variability of Arctic sea ice thickness and volume from CryoSat-2.

    Science.gov (United States)

    Kwok, R; Cunningham, G F

    2015-07-13

    We present our estimates of the thickness and volume of the Arctic Ocean ice cover from CryoSat-2 data acquired between October 2010 and May 2014. Average ice thickness and draft differences are within 0.16 m of measurements from other sources (moorings, submarine, electromagnetic sensors, IceBridge). The choice of parameters that affect the conversion of ice freeboard to thickness is discussed. Estimates between 2011 and 2013 suggest moderate decreases in volume followed by a notable increase of more than 2500 km(3) (or 0.34 m of thickness over the basin) in 2014, which could be attributed to not only a cooler summer in 2013 but also to large-scale ice convergence just west of the Canadian Arctic Archipelago due to wind-driven onshore drift. Variability of volume and thickness in the multiyear ice zone underscores the importance of dynamics in maintaining the thickness of the Arctic ice cover. Volume estimates are compared with those from ICESat as well as the trends in ice thickness derived from submarine ice draft between 1980 and 2004. The combined ICESat and CryoSat-2 record yields reduced trends in volume loss compared with the 5 year ICESat record, which was weighted by the record-setting ice extent after the summer of 2007.

  9. Distinct bacterial assemblages reside at different depths in Arctic multiyear sea ice.

    Science.gov (United States)

    Hatam, Ido; Charchuk, Rhianna; Lange, Benjamin; Beckers, Justin; Haas, Christian; Lanoil, Brian

    2014-10-01

    Bacterial communities in Arctic sea ice play an important role in the regulation of nutrient and energy dynamics in the Arctic Ocean. Sea ice has vertical gradients in temperature, brine salinity and volume, and light and UV levels. Multiyear ice (MYI) has at least two distinct ice layers: old fresh ice with limited permeability, and new saline ice, and may also include a surface melt pond layer. Here, we determine whether bacterial communities (1) differ with ice depth due to strong physical and chemical gradients, (2) are relatively homogenous within a layer, but differ between layers, or (3) do not vary with ice depth. Cores of MYI off northern Ellesmere Island, NU, Canada, were subsectioned in 30-cm intervals, and the bacterial assemblage structure was characterized using 16S rRNA gene pyrotag sequencing. Assemblages clustered into three distinct groups: top (0-30 cm); middle (30-150 cm); and bottom (150-236 cm). These layers correspond to the occurrence of refrozen melt pond ice, at least 2-year-old ice, and newly grown first-year ice at the bottom of the ice sheet, respectively. Thus, MYI houses multiple distinct bacterial assemblages, and in situ conditions appear to play a less important role in structuring microbial assemblages than the age or conditions of the ice at the time of formation.

  10. Interannual variations of the dominant modes of East Asian winter monsoon and possible links to Arctic sea ice

    Science.gov (United States)

    Sun, Chenghu; Yang, Song; Li, Weijing; Zhang, Ruonan; Wu, Renguang

    2016-07-01

    Two dominant modes of the winter temperature over East Asia, a northern mode and a southern mode, and their links with Arctic climate conditions are analyzed. The relationships of the two modes with Arctic sea ice are different. The northern mode is closely linked to variations in sea ice of the Arctic Barents-Laptev Sea in previous autumn and most of the Arctic in concurrent winter. The southern mode seems independent from the Arctic sea ice variations, but is associated with sea surface temperature (SST) anomalies in the equatorial central-eastern Pacific. Results suggest an effect of Arctic sea ice variation on the northern mode and an influence of tropical SST anomalies on the southern mode. Reduced sea ice over the Arctic increases 1000-500-hPa thickness over the high-latitudes of Eurasian continent, which reduces the meridional thickness gradient between the middle and high latitudes and thus weakens the extratropical upper-level zonal wind. The weakened zonal wind provides a favorable dynamic condition for the development of a high-latitude ridge around the Ural Mountain. Reduced Arctic sea ice also tends to enhance the Siberian high through both thermodynamic and dynamic processes. The above atmospheric circulation patterns provide a favorable condition for the intrusion of cold air to northern East Asia.

  11. An Arctic Ice/Ocean Coupled Model with Wave Interactions

    Science.gov (United States)

    2015-09-30

    ocean waves and sea ice interact, for use in operational models of the Arctic Basin and the adjacent seas; – improve the forecasting capacities of...spectra and modify their directional spread. Being the primary focus of the current project, we are developing innovative methods to model these...during WIFAR (Waves-in-Ice Forecasting for Arctic Operators), a partnership between the Nansen Environmental and Remote Sensing Center (NERSC) in

  12. A recent bifurcation in Arctic sea-ice cover

    Directory of Open Access Journals (Sweden)

    V. N. Livina

    2012-07-01

    Full Text Available There is ongoing debate over whether Arctic sea-ice has already passed a "tipping point", or whether it will do so in future, with several recent studies arguing that the loss of summer sea ice does not involve a bifurcation because it is highly reversible in models. Recently developed methods can detect and sometimes forewarn of bifurcations in time-series data, hence we applied them to satellite data for Arctic sea-ice cover. Here we show that a new low ice cover state has appeared from 2007 onwards, which is distinct from the normal state of seasonal sea ice variation, suggesting a bifurcation has occurred from one attractor to two. There was no robust early warning signal of critical slowing down prior to this bifurcation, consistent with it representing the appearance of a new ice cover state rather than the loss of stability of the existing state. The new low ice cover state has been sampled predominantly in summer-autumn and seasonal forcing combined with internal climate variability are likely responsible for triggering recent transitions between the two ice cover states. However, all early warning indicators show destabilization of the summer-autumn sea-ice since 2007. This suggests the new low ice cover state may be a transient feature and further abrupt changes in summer-autumn Arctic sea-ice cover could lie ahead; either reversion to the normal state or a yet larger ice loss.

  13. Impact of Arctic sea ice loss on large-scale atmospheric circulation based on fully-coupled sensitivity experiments

    Science.gov (United States)

    Oudar, Thomas; Sanchez, Emilia; Terray, Laurent; Chauvin, Fabrice

    2016-04-01

    Arctic sea ice decline in the recent decades has been reported in observational studies. Modeling studies have confirmed that this downward trend in Arctic sea ice is mainly caused by increasing Greenhouse Gases (GHGs) concentrations into the atmosphere. The IPCC-AR5 report concluded that Arctic sea ice will continue to decrease and is projected to disappear in the middle of the 21st century, yielding to a ice-free region during boreal summer season. Arctic sea ice loss is expected to strongly impact the climate system. Recently, the climate community has conducted a number of studies to evaluate and understand the Arctic sea ice loss implications on climate. While some studies have shown that Arctic sea ice decline can significantly affect the large-scale atmospheric dynamics at high and mid-latitudes of the Northern Hemisphere, by altering the storm-tracks, the jet stream (position and strength) and the planetary waves, large uncertainties remain due to a low signal-to-noise ratio and experimental protocol differences leading to a large inter-model spread. In this work, we investigate the respective roles of Arctic sea ice loss and GHGs increase on the atmospheric dynamics by means of an idealized experimental set-up that uses the coupled model CNRM-CM5. The experimental set-up, based on a flux correction technique, will allow separating the contributions of Arctic sea ice loss from the GHGs increasing. We will focus mainly on the atmospheric circulation response in the Northern Hemisphere and on the associated synoptic variability, represented by the storm-tracks. We show that Arctic sea ice loss is responsible for an equatorward shift of the northern hemisphere jet, which is opposed to the GHGs effect. Finally we show that these shifts are consistent with the storm-tracks response.

  14. Fine-resolution simulation of surface current and sea ice in the Arctic Mediterranean Seas

    Institute of Scientific and Technical Information of China (English)

    LIU Xiying; ZHANG Xuehong; YU Rucong; LIU Hailong; LI Wei

    2007-01-01

    A fine-resolution model is developed for ocean circulation simulation in the National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG),Chinese Academy of Sciences, and is applied to simulate surface current and sea ice variations in the Arctic Mediterranean Seas. A dynamic sea ice model in elastic-viscous-plastic rheology and a thermodynamic sea ice model are employed. A 200-year simulation is performed and a dimatological average of a 10-year period (141 st-150 th) is presented with focus on sea ice concentration and surface current variations in the Arctic Mediterranean Seas. The model is able to simulate well the East Greenland Current, Beaufort Gyre and the Transpolar Drift, but the simulated West Spitsbergen Current is small and weak. In the March climatology, the sea ice coverage can be simulated well except for a bit more ice in east of Spitsbergen Island. The result is also good for the September scenario except for less ice concentration east of Greenland and greater ice concentration near the ice margin. The extra ice east of Spitsbergen Island is caused by sea ice current convergence forced by atmospheric wind stress.

  15. Arctic sea ice decline contributes to thinning lake ice trend in northern Alaska

    Science.gov (United States)

    Alexeev, Vladimir A.; Arp, Christopher D.; Jones, Benjamin M.; Cai, Lei

    2016-07-01

    Field measurements, satellite observations, and models document a thinning trend in seasonal Arctic lake ice growth, causing a shift from bedfast to floating ice conditions. September sea ice concentrations in the Arctic Ocean since 1991 correlate well (r = +0.69, p Weather Research and Forecasting model output produced a 7% decrease in lake ice growth when 2007/08 sea ice was imposed on 1991/92 climatology and a 9% increase in lake ice growth for the opposing experiment. Here, we clearly link early winter ‘ocean-effect’ snowfall and warming to reduced lake ice growth. Future reductions in sea ice extent will alter hydrological, biogeochemical, and habitat functioning of Arctic lakes and cause sub-lake permafrost thaw.

  16. Radiative Impacts of Further Arctic Sea Ice Melt: Using past Observations to Inform Future Climate Impacts

    Science.gov (United States)

    Pistone, K.; Eisenman, I.; Ramanathan, V.

    2017-01-01

    The Arctic region has seen dramatic changes over the past several decades, from polar amplification of global temperature rise to ecosystem changes to the decline of the sea ice. While there has been much speculation as to when the world will see an ice-free Arctic, the radiative impacts of an eventual disappearance of the Arctic sea ice are likely to be significant regardless of the timing. Using CERES radiation and microwave satellite sea ice data, Pistone et al (2014) estimated the radiative forcing due to albedo changes associated with the Arctic sea ice retreat over the 30 years of the satellite data record. In this study, we found that the Arctic Ocean saw a decrease in all-sky albedo of 4% (from 52% to 48%), for an estimated increase in solar heating of 6.4 W/m(exp 2) between 1979 and 2011, or 0.21 W/m(exp 2) when averaged over the globe. This value is substantial--approximately 25% as large as the forcing due to the change in CO2 during the same period. Here we update and expand upon this previous work and use the CERES broadband shortwave observations to explore the radiative impacts of a transition to completely ice-free Arctic Ocean. We estimate the annually-averaged Arctic Ocean planetary albedo under ice-free and cloud-free conditions to be 14% over the region, or approximately 25% lower in absolute terms than the Arctic Ocean cloud-free albedo in 1979. However, the question of all-sky conditions (i.e. including the effects of clouds) introduces a new level of complexity. We explore several cloud scenarios and the resultant impact on albedo. In each of these cases, the estimated forcing is not uniformly distributed throughout the year. We describe the relative contributions of ice loss by month as well as the spatial distributions of the resulting changes in absorbed solar energy. The seasonal timing and location—in addition to magnitude—of the altered solar absorption may have significant implications for atmospheric and ocean dynamics in the

  17. Interdecadal changes in snow depth on Arctic sea ice

    Science.gov (United States)

    Webster, Melinda A.; Rigor, Ignatius G.; Nghiem, Son V.; Kurtz, Nathan T.; Farrell, Sinead L.; Perovich, Donald K.; Sturm, Matthew

    2014-08-01

    Snow plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and IceBridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.1 ± 9.4 to 22.2 ± 1.9 cm in the western Arctic, and from 32.8 ± 9.4 to 14.5 ± 1.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37 ± 29% in the western Arctic and 56 ± 33% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

  18. Arctic Autumn Air-Ice-Ocean Interactions Resulting from Recent Sea-ice Decline

    Science.gov (United States)

    Persson, Ola; Blomquist, Byron; Fairall, Christopher; Guest, Peter; Stammerjohn, Sharon; Rainville, Luc; Thomson, Jim; Smith, Madison; Tjernström, Michael; Solomon, Amy

    2017-04-01

    The recent decline in Arctic sea-ice extent has produced large areas of open water in September that were previously ice covered. Autumn air-ice-ocean interactions in these regions are now characterized by ice-edge or marginal ice zone (MIZ) processes rather than by primarily air-ice refreezing processes. This study will utilize field program measurements to illustrate this change in processes, provide examples of new processes, and to quantify changes in energy fluxes resulting from some of the key processes. Observations from SHEBA (1998) and near the North Pole during ASCOS (2008) are used to illustrate freeze-up over existing sea ice ("old Arctic" processes) while observations from ACSE (2014), Mirai (2014), and Sea State (2015), supplemented with mesoscale model output, are used to illustrate "new Arctic" processes. In the "old Arctic", energy budgets show that freeze-up over remaining end-of-season sea ice occurred in late August, primarily because of the high albedo of the ice enhanced by snowfall events. In the "new Arctic" with extensive open water, summertime upper-ocean heating, formation of atmospheric ice-edge fronts, atmospheric thermal circulations, formation of thin new ice, ocean waves, and upper-ocean mixing all play a role in the autumn freeze-up process. These new processes also significantly impact the temporal extent and magnitude of the ocean heat loss to the atmosphere during this critical season from September to November, and possibly beyond. The magnitude of this heat loss plays an important role in various hypotheses regarding the impact of Arctic sea-ice loss on mid-latitude atmospheric circulations. While these hypotheses will not be discussed, the observations directly provide estimates of heat loss magnitudes in the "old Arctic" and the "new Arctic", thereby quantifying changes in heat loss, which can then be used to assess the accuracy of the various models and reanalyses.

  19. The Arctic Ocean ice balance - A Kalman smoother estimate

    Science.gov (United States)

    Thomas, D. R.; Rothrock, D. A.

    1993-01-01

    The methodology of Kalman filtering and smoothing is used to integrate a 7-year time series of buoy-derived ice motion fields and satellite passive microwave observations. The result is a record of the concentrations of open water, first-year ice, and multiyear ice that we believe is better than the estimates based on the microwave data alone. The Kalman procedure interprets the evolution of the ice cover in terms of advection, melt, growth, ridging, and aging of first-year into multiyear ice. Generally, the regions along the coasts of Alaska and Siberia and the area just north of Fram Strait are sources of first-year ice, with the rest of the Arctic Ocean acting as a sink for first-year ice via ridging and aging. All the Arctic Ocean except for the Beaufort and Chukchi seas is a source of multiyear ice, with the Chukchi being the only internal multiyear ice sink. Export through Fram Strait is a major ice sink, but we find only about two-thirds the export and greater interannual variation than found in previous studies. There is no discernible trend in the area of multiyear ice in the Arctic Ocean during the 7 years.

  20. Robust seasonal cycle of Arctic sea ice area through tipping point in amplitude

    CERN Document Server

    Ditlevsen, Peter D

    2012-01-01

    The variation in the Arctic sea ice is dominated by the seasonal cycle with little inter-annual correlation. Though the mean sea ice area has decreased steadily in the period of satellite observations, a dramatic transition in the dynamics was initiated with the record low September ice area in 2007. The change is much more pronounced in the amplitude of the seasonal cycle than in the annual mean ice area. The shape of the seasonal cycle is surprisingly constant for the whole observational record despite the general decline. A simple explanation, independent of the increased greenhouse warming, for the shape of the seasonal cycle is offered. Thus the dramatic climate change in arctic ice area is seen in the amplitude of the cycle and to a lesser extend the annual mean and the summer ice extend. The reason why the climate change is most pronounced in the amplitude is related to the rapid reduction in perennial ice and thus a thinning of the ice. The analysis shows that a tipping point for the arctic ice area w...

  1. On the Role of Arctic Sea Ice Deformations: An Evaluation of the Regional Arctic System Model Results with Observations.

    Science.gov (United States)

    Osinski, Robert; Maslowski, Wieslaw; Roberts, Andrew

    2016-04-01

    The atmosphere - sea ice - ocean fluxes and their contribution to rapid changes in the Arctic system are not well understood and generally are not resolved by global climate models (GCMs). While many significant model refinements have been made in the recent past, including the representation of sea ice rheology, surface albedo and ice-albedo feedback, other processes such as sea ice deformations, still require further studies and model advancements. Of particular potential interest here are linear kinematic features (LKFs), which control winter air-sea heat exchange and affect buoyancy forces in the ocean. Their importance in Arctic climate change, especially under an increasing first-year ice cover, is yet to be determined and their simulation requires representation of processes currently at sub-grid scale of most GCMs. To address some of the GCM limitations and to better understand the role of LKFs in air-sea exchange we use the Regional Arctic System Model (RASM), which allows high spatio-temporal resolution and regional focus on the Arctic. RASM is a fully coupled regional climate model, developed to study dynamic and thermodynamic processes and their coupling across the atmosphere-sea ice-ocean interface. It consists of the Weather Research and Forecasting (WRF) atmospheric model, the Parallel Ocean Program (POP), the Community Ice Model (CICE) and the Variable Infiltration Capacity (VIC) land hydrology model. The sea ice component has been upgraded to the Los Alamos Community Ice Model version 5.1 (CICE5.1), which allows either Elastic-Viscous-Plastic (EVP) or a new anisotropic (EPA) rheology. RASM's domain is pan-Arctic, with the ocean and sea ice components configured at an eddy-permitting horizontal resolution of 1/12-degree as well as 1/48-degree, for limited simulations. The atmosphere and land model components are configured at 50-km grids. All the components are coupled at a 20-minute time step. Results from multiple RASM simulations are analyzed and

  2. Evidence for middle Eocene Arctic sea ice from diatoms and ice-rafted debris.

    Science.gov (United States)

    Stickley, Catherine E; St John, Kristen; Koç, Nalân; Jordan, Richard W; Passchier, Sandra; Pearce, Richard B; Kearns, Lance E

    2009-07-16

    Oceanic sediments from long cores drilled on the Lomonosov ridge, in the central Arctic, contain ice-rafted debris (IRD) back to the middle Eocene epoch, prompting recent suggestions that ice appeared in the Arctic about 46 million years (Myr) ago. However, because IRD can be transported by icebergs (derived from land-based ice) and also by sea ice, IRD records are restricted to providing a history of general ice-rafting only. It is critical to differentiate sea ice from glacial (land-based) ice as climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean-atmosphere exchanges, whereas land-based ice affects sea level and consequently ocean acidity. An earlier report assumed that sea ice was prevalent in the middle Eocene Arctic on the basis of IRD, and although somewhat preliminary supportive evidence exists, these data are neither comprehensive nor quantified. Here we show the presence of middle Eocene Arctic sea ice from an extraordinary abundance of a group of sea-ice-dependent fossil diatoms (Synedropsis spp.). Analysis of quartz grain textural characteristics further supports sea ice as the dominant transporter of IRD at this time. Together with new information on cosmopolitan diatoms and existing IRD records, our data strongly suggest a two-phase establishment of sea ice: initial episodic formation in marginal shelf areas approximately 47.5 Myr ago, followed approximately 0.5 Myr later by the onset of seasonally paced sea-ice formation in offshore areas of the central Arctic. Our data establish a 2-Myr record of sea ice, documenting the transition from a warm, ice-free environment to one dominated by winter sea ice at the start of the middle Eocene climatic cooling phase.

  3. Arctic Tides from GPS on sea-ice

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

    2013-01-01

    The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea-ice dampens the ocean tide amplitude with the result that global tidal models perform less accurately in the polar regions. This paper presents, a kinematic processing of global positioning system (GPS......) placed on sea-ice, at six different sites north of Greenland for the preliminary study of sea surface height (SSH), and tidal analysis to improve tide models in the Central Arctic. The GPS measurements are compared with the Arctic tide model AOTIM-5, which assimilates tide-gauges and altimetry data....... The results show coherence between the GPS buoy measurements, and the tide model. Furthermore, we have proved that the reference ellipsoid of WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

  4. Ocean surface waves in an ice-free Arctic Ocean

    Science.gov (United States)

    Li, Jian-Guo

    2016-08-01

    The retreat of the Arctic ice edge implies that global ocean surface wave models have to be extended at high latitudes or even to cover the North Pole in the future. The obstacles for conventional latitude-longitude grid wave models to cover the whole Arctic are the polar problems associated with their Eulerian advection schemes, including the Courant-Friedrichs-Lewy (CFL) restriction on diminishing grid length towards the Pole, the singularity at the Pole and the invalid scalar assumption for vector components defined relative to the local east direction. A spherical multiple-cell (SMC) grid is designed to solve these problems. It relaxes the CFL restriction by merging the longitudinal cells towards the Poles. A round polar cell is used to remove the singularity of the differential equation at the Pole. A fixed reference direction is introduced to define vector components within a limited Arctic part in mitigation of the scalar assumption errors at high latitudes. The SMC grid has been implemented in the WAVEWATCH III model and validated with altimeter and buoy observations, except for the Arctic part, which could not be fully tested due to a lack of observations as the polar region is still covered by sea ice. Here, an idealised ice-free Arctic case is used to test the Arctic part and it is compared with a reference case with real ice coverage. The comparison indicates that swell wave energy will increase near the ice-free Arctic coastlines due to increased fetch. An expanded Arctic part is used for comparisons of the Arctic part with available satellite measurements. It also provides a direct model comparison between the two reference systems in their overlapping zone.

  5. Albedo changes of the Arctic sea ice cover

    Science.gov (United States)

    Perovich, D. K.; Light, B.; Jones, K. F.; Eicken, H.; Runciman, K.; Nghiem, S. V.; Stroeve, J.; Markus, T.

    2008-12-01

    The summer extent of the Arctic sea ice cover has decreased in recent decades and there have been alterations in the timing and duration of the summer melt season. This has resulted in changes in the evolution of albedo of the Arctic sea ice cover, and consequently in the partitioning of solar energy. These changes are examined on a pan-Arctic scale on a 25 x 25 km Equal Area Scalable Earth Grid for the years 1979 - 2007. Daily values of incident solar irradiance are obtained from ERA-40 reanalysis products and ice concentrations are determined from passive microwave satellite data. The albedo of the ice is modeled by a five-phase process that includes dry snow, melting snow, melt pond formation, melt pond evolution, and freezeup. The timing of these phases is governed by the onset dates of summer melt and fall freezeup, which are determined from satellite observations. Results indicate a general trend of increasing solar heat input to the Arctic ice-ocean system due to reductions in ice concentration and longer melt seasons. This trend may accelerate the loss of sea ice through the ice-albedo feedback. The evolution of albedo, and hence the total solar heating of the ocean, is more sensitive to the date of melt onset than the date of fall freezeup.

  6. Arctic sea ice reaches second lowest in satellite record

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Xinhua reports that the blanket of sea ice that floats on the Arctic Ocean appears to have reached its lowest extent for 2011, the second lowest recorded since satellites began measuring it in 1979, according to a report released on September 15 by the University of Colorado Boulder's National Snow and Ice Data Center (NSIDC).

  7. Large-Scale Surveys of Snow Depth on Arctic Sea Ice from Operation IceBridge

    Science.gov (United States)

    Kurtz, Nathan T.; Farrell, Sinead L.

    2011-01-01

    We show the first results of a large ]scale survey of snow depth on Arctic sea ice from NASA fs Operation IceBridge snow radar system for the 2009 season and compare the data to climatological snow depth values established over the 1954.1991 time period. For multiyear ice, the mean radar derived snow depth is 33.1 cm and the corresponding mean climatological snow depth is 33.4 cm. The small mean difference suggests consistency between contemporary estimates of snow depth with the historical climatology for the multiyear ice region of the Arctic. A 16.5 cm mean difference (climatology minus radar) is observed for first year ice areas suggesting that the increasingly seasonal sea ice cover of the Arctic Ocean has led to an overall loss of snow as the region has transitioned away from a dominantly multiyear ice cover.

  8. Shrinking sea ice, increasing snowfall and thinning lake ice: a complex Arctic linkage explained

    Science.gov (United States)

    Brock, Ben W.

    2016-09-01

    The dramatic shrinkage of Arctic sea ice is one of the starkest symptoms of global warming, with potentially severe and far-reaching impacts on arctic marine and terrestrial ecology (Post et al 2013 Science 341 519-24) and northern hemisphere climate (Screen et al 2015 Environ. Res. Lett. 10 084006). In their recent article, Alexeev et al (2016 Environ. Res. Lett. 11 074022) highlight another, and unexpected, consequence of Arctic sea ice retreat: the thinning of lake ice in northern Alaska. This is attributed to early winter ‘ocean effect’ snowfall which insulates lake surfaces and inhibits the formation of deep lake ice. Lake ice thinning has important consequences for Arctic lake hydrology, biology and permafrost degradation.

  9. Physical Characteristics and Geobiology of 'Rotten' Arctic Sea Ice

    Science.gov (United States)

    Frantz, C. M.; Light, B.; Orellana, M. V.; Carpenter, S.; Junge, K.

    2015-12-01

    Arctic sea ice in its final stage of demise, "rotten ice", is characterized by seriously compromised structural integrity, making it difficult to collect and study. Consequently, little is known about the physical, chemical and biological properties of this ice type. Yet, as the Arctic melt season lengthens, this ice type will likely appear sooner and become more prevalent in the Arctic Ocean and its occurrence may be more common than satellite mapping and ice charts suggest (e.g., Barber et al., 2009). Here we present physical, chemical, biological, and optical measurements of first-year ice near Barrow, Alaska during the spring and summer of 2015. Samples represent a progression from solid, "springtime" shorefast ice (May); through melting, heavily melt-ponded, "summertime" shorefast ice (June); to the final stage of barely-intact, "rotten" ice collected from small floes Beaufort Sea (July). Results indicate that rotten ice exhibits low salinity, is well drained and has a lower density than its springtime counterpart. X-ray tomography of dimethyl phthalate-casted sea ice samples indicates differences in porosity and relative permeability in rotten ice vs. spring- and summertime ice. We also present a preliminary characterization of rotten sea ice as a microbial habitat using preliminary results of chemical measurements (nutrients, dissolved organic and inorganic carbon), and microbiological characterizations (concentrations and16S/18S rDNA-based identifications) from seawater vs. sea ice vs. sea ice brines. Optical measurements show that while decreased ice thickness and increased melt pond coverage cause an overall increase in solar radiation to the ocean as sea ice warms, rotten ice is actually less transparent to solar radiation than its spring- and summertime counterparts. These factors determine solar heating in the ocean and, ultimately, the potential for accelerated ice melting (e.g., Light et al., 2008). This work provides a foundation for understanding

  10. Definition of Arctic and Antarctic Sea Ice Variation Index

    Institute of Scientific and Technical Information of China (English)

    Chen Hongxia; Liu Na; Pan Zengdi; Zhang Qinghua

    2004-01-01

    It is well known that varying of the sea ice not only in the Antarctic but also in the Arctic has an active influence on the globe atmosphere and ocean. In order to understand the sea ice variation in detail, for the first time, an objective index of the Arctic and Antarctic sea ice variation is defined by projecting the monthly sea ice concentration anomalies poleward of 20°N or 20°S onto the EOF (empirical orthogonal function)-1 spatial pattern. Comparing with some work in former studies of polar sea ice, the index has the potential for clarifying the variability of sea ice in northern and southern high latitudes.

  11. Convective forcing of mercury and ozone in the Arctic boundary layer induced by leads in sea ice.

    Science.gov (United States)

    Moore, Christopher W; Obrist, Daniel; Steffen, Alexandra; Staebler, Ralf M; Douglas, Thomas A; Richter, Andreas; Nghiem, Son V

    2014-02-06

    The ongoing regime shift of Arctic sea ice from perennial to seasonal ice is associated with more dynamic patterns of opening and closing sea-ice leads (large transient channels of open water in the ice), which may affect atmospheric and biogeochemical cycles in the Arctic. Mercury and ozone are rapidly removed from the atmospheric boundary layer during depletion events in the Arctic, caused by destruction of ozone along with oxidation of gaseous elemental mercury (Hg(0)) to oxidized mercury (Hg(II)) in the atmosphere and its subsequent deposition to snow and ice. Ozone depletion events can change the oxidative capacity of the air by affecting atmospheric hydroxyl radical chemistry, whereas atmospheric mercury depletion events can increase the deposition of mercury to the Arctic, some of which can enter ecosystems during snowmelt. Here we present near-surface measurements of atmospheric mercury and ozone from two Arctic field campaigns near Barrow, Alaska. We find that coastal depletion events are directly linked to sea-ice dynamics. A consolidated ice cover facilitates the depletion of Hg(0) and ozone, but these immediately recover to near-background concentrations in the upwind presence of open sea-ice leads. We attribute the rapid recoveries of Hg(0) and ozone to lead-initiated shallow convection in the stable Arctic boundary layer, which mixes Hg(0) and ozone from undepleted air masses aloft. This convective forcing provides additional Hg(0) to the surface layer at a time of active depletion chemistry, where it is subject to renewed oxidation. Future work will need to establish the degree to which large-scale changes in sea-ice dynamics across the Arctic alter ozone chemistry and mercury deposition in fragile Arctic ecosystems.

  12. A Comparative Study of Antarctic Arctic and Himalayan Ice

    Directory of Open Access Journals (Sweden)

    R. C. Pathak

    1989-07-01

    Full Text Available Arctic, Antarctic and inaccessible lofty regions of Himalayas,which are geographically diverse areas and have been a constant source of inspiration, envisages a challenging field of study 'by early adventurers and scientists of the world. Characteristics of ice obtained at Arctic and Antarctic do not possess similar properties. Even thesalient properties of snow and ice of western and central Himalayas vary due to its differing free water content. A study has been carriedout based on recent Antarctic Expedition by Indian scientists and the data gathered along litha-tectonic regions of Himalayas and their characteristics have been compared, wkich brings out stratigraphic and metamorphic characteristics of the ice and snow. In the present paper,an analysis of the ice and snow properties of Arctic, Antarctic and Himalayan regions has been presented.

  13. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-09-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  14. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core.

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Dahl-Jensen, Dorthe

    2016-09-21

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called "bromine explosions" and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement.

  15. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core

    Science.gov (United States)

    Spolaor, Andrea; Vallelonga, Paul; Turetta, Clara; Maffezzoli, Niccolò; Cozzi, Giulio; Gabrieli, Jacopo; Barbante, Carlo; Goto-Azuma, Kumiko; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Dahl-Jensen, Dorthe

    2016-01-01

    Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice. We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values. First-year sea ice extent was lowest during the glacial stadials suggesting complete coverage of the Arctic Ocean by multi-year sea ice. These findings demonstrate a clear relationship between temperature and first-year sea ice extent in the Arctic and suggest multi-year sea ice will continue to decline as polar amplification drives Arctic temperatures beyond the 2 °C global average warming target of the recent COP21 Paris climate agreement. PMID:27650478

  16. The fate of lake ice in the North American Arctic

    Directory of Open Access Journals (Sweden)

    L. C. Brown

    2011-07-01

    Full Text Available Lakes comprise a large portion of the surface cover in northern North America forming an important part of the cryosphere. The timing of lake ice phenological events (e.g. break-up/freeze-up are useful indicators of climate variability and change, which is of particular relevance in environmentally sensitive areas such as the North American Arctic. Further alterations to the present day ice regime could result in major ecosystem changes, such as species shifts and the disappearance of perennial ice cover. Lake ice models are a valuable tool for examining the response of lake ice cover to changing climate conditions. The use of future climate scenario data in these models can provide information on the potential changes in ice phenology, ice thickness and composition. The Canadian Lake Ice Model (CLIMo was used to simulate lake ice phenology across the North American Arctic from 1961–2100 using climate scenarios produced by the Canadian Regional Climate Model (CRCM. Results from the 1961–1990 time period were validated using 15 locations across the Canadian Arctic, with both in situ ice cover observations from the Canadian Ice Database as well as additional ice cover simulations using nearby weather station data. Projected changes to the ice cover using the 30 yr mean data between 1961–1990 and 2041–2070 suggest a shift towards shorter ice cover durations by an average of just over 3 weeks, with a 25 cm average reduction of the total ice thickness – varying based on location, lake depth and snow cover amounts.

  17. Controls on Arctic sea ice from first-year and multi-year ice survival rates

    Science.gov (United States)

    Armour, K.; Bitz, C. M.; Hunke, E. C.; Thompson, L.

    2009-12-01

    The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi-year (MY) ice. The transition to an Arctic that is populated by thinner first-year (FY) sea ice has important implications for future trends in area and volume. We develop a reduced model for Arctic sea ice with which we investigate how the survivability of FY and MY ice control various aspects of the sea-ice system. We demonstrate that Arctic sea-ice area and volume behave approximately as first-order autoregressive processes, which allows for a simple interpretation of September sea-ice in which its mean state, variability, and sensitivity to climate forcing can be described naturally in terms of the average survival rates of FY and MY ice. This model, used in concert with a sea-ice simulation that traces FY and MY ice areas to estimate the survival rates, reveals that small trends in the ice survival rates explain the decline in total Arctic ice area, and the relatively larger loss of MY ice area, over the period 1979-2006. Additionally, our model allows for a calculation of the persistence time scales of September area and volume anomalies. A relatively short memory time scale for ice area (~ 1 year) implies that Arctic ice area is nearly in equilibrium with long-term climate forcing at all times, and therefore observed trends in area are a clear indication of a changing climate. A longer memory time scale for ice volume (~ 5 years) suggests that volume can be out of equilibrium with climate forcing for long periods of time, and therefore trends in ice volume are difficult to distinguish from its natural variability. With our reduced model, we demonstrate the connection between memory time scale and sensitivity to climate forcing, and discuss the implications that a changing memory time scale has on the trajectory of ice area and volume in a warming climate. Our findings indicate that it is unlikely that a “tipping point” in September ice area and volume will be

  18. Characterizing "Rotten" Ice: Changes in first-year Arctic sea ice during advanced summer melt

    Science.gov (United States)

    Frantz, C. M.; Junge, K.; Light, B.; Orellana, M. V.; Carpenter, S.; Farley, S. M.; Crump, B. C.; Lieb-Lappen, R.; Courville, Z.

    2016-12-01

    Arctic melt seasons are lengthening; as this happens, more Arctic sea ice will undergo advanced stages of melt, becoming so-called "rotten" ice. However, very little is known about this increasingly important ice type. Here, we present results of a physical, optical, chemical, and biological characterization of rotten Arctic sea ice. Sea ice core samples and measurements were collected from landfast sea ice and summer ice floes near Barrow, Alaska during May-July of 2015. We captured a normal progression of ice warming and freshening from May-June which contrasted sharply to physical properties and biological composition of the "rotten" ice targeted in July. Rotten ice is approximately isothermal and highly permeable, a consequence of its characteristic multi-cm-scale brine channels, resulting in an ice that is largely drained of brine and flushed with seawater. 3D micro-CT images of the ice allow us to quantify the evolution of factors related to ice porosity and channel connectivity in May-June vs. rotten ice. Patterns in measured chemistry show an environment in rotten ice that is distinct from May-June ice as well as from the seawater that underlies and permeates the ice. The physical and chemical parameters taken together represent an entirely different microbial habitat than the saline ice of May and June. Correspondingly, the sea ice microbial community also changes significantly over the course of melt. The ice-bottom algal community that dominates the biomass of the cores in May and June was lost by July, yet in July samples some algae appear to remain embedded in or attached to the ice throughout the full core depth. In addition, bacterial counts in upper horizons of rotten ice were dramatically higher than those observed in May-June. Pending results from SSU rRNA amplicon sequencing and exopolymer/gel analyses will also be presented.

  19. Arctic and Antarctic Sea Ice Changes and Impacts (Invited)

    Science.gov (United States)

    Nghiem, S. V.

    2013-12-01

    The extent of springtime Arctic perennial sea ice, important to preconditioning summer melt and to polar sunrise photochemistry, continues its precipitous reduction in the last decade marked by a record low in 2012, as the Bromine, Ozone, and Mercury Experiment (BROMEX) was conducted around Barrow, Alaska, to investigate impacts of sea ice reduction on photochemical processes, transport, and distribution in the polar environment. In spring 2013, there was further loss of perennial sea ice, as it was not observed in the ocean region adjacent to the Alaskan north coast, where there was a stretch of perennial sea ice in 2012 in the Beaufort Sea and Chukchi Sea. In contrast to the rapid and extensive loss of sea ice in the Arctic, Antarctic sea ice has a trend of a slight increase in the past three decades. Given the significant variability in time and in space together with uncertainties in satellite observations, the increasing trend of Antarctic sea ice may arguably be considered as having a low confidence level; however, there was no overall reduction of Antarctic sea ice extent anywhere close to the decreasing rate of Arctic sea ice. There exist publications presenting various factors driving changes in Arctic and Antarctic sea ice. After a short review of these published factors, new observations and atmospheric, oceanic, hydrological, and geological mechanisms contributed to different behaviors of sea ice changes in the Arctic and Antarctic are presented. The contribution from of hydrologic factors may provide a linkage to and enhance thermal impacts from lower latitudes. While geological factors may affect the sensitivity of sea ice response to climate change, these factors can serve as the long-term memory in the system that should be exploited to improve future projections or predictions of sea ice changes. Furthermore, similarities and differences in chemical impacts of Arctic and Antarctic sea ice changes are discussed. Understanding sea ice changes and

  20. Arctic warming: nonlinear impacts of sea-ice and glacier melt on seabird foraging.

    Science.gov (United States)

    Grémillet, David; Fort, Jérôme; Amélineau, Françoise; Zakharova, Elena; Le Bot, Tangi; Sala, Enric; Gavrilo, Maria

    2015-03-01

    Arctic climate change has profound impacts on the cryosphere, notably via shrinking sea-ice cover and retreating glaciers, and it is essential to evaluate and forecast the ecological consequences of such changes. We studied zooplankton-feeding little auks (Alle alle), a key sentinel species of the Arctic, at their northernmost breeding site in Franz-Josef Land (80°N), Russian Arctic. We tested the hypothesis that little auks still benefit from pristine arctic environmental conditions in this remote area. To this end, we analysed remote sensing data on sea-ice and coastal glacier dynamics collected in our study area across 1979-2013. Further, we recorded little auk foraging behaviour using miniature electronic tags attached to the birds in the summer of 2013, and compared it with similar data collected at three localities across the Atlantic Arctic. We also compared current and historical data on Franz-Josef Land little auk diet, morphometrics and chick growth curves. Our analyses reveal that summer sea-ice retreated markedly during the last decade, leaving the Franz-Josef Land archipelago virtually sea-ice free each summer since 2005. This had a profound impact on little auk foraging, which lost their sea-ice-associated prey. Concomitantly, large coastal glaciers retreated rapidly, releasing large volumes of melt water. Zooplankton is stunned by cold and osmotic shock at the boundary between glacier melt and coastal waters, creating new foraging hotspots for little auks. Birds therefore switched from foraging at distant ice-edge localities, to highly profitable feeding at glacier melt-water fronts within <5 km of their breeding site. Through this behavioural plasticity, little auks maintained their chick growth rates, but showed a 4% decrease in adult body mass. Our study demonstrates that arctic cryosphere changes may have antagonistic ecological consequences on coastal trophic flow. Such nonlinear responses complicate modelling exercises of current and future

  1. Physical characteristics of summer sea ice across the Arctic Ocean

    Science.gov (United States)

    Tucker, W. B.; Gow, A.J.; Meese, D.A.; Bosworth, H.W.; Reimnitz, E.

    1999-01-01

    Sea ice characteristics were investigated during July and August on the 1994 transect across the Arctic Ocean. Properties examined from ice cores included salinity, temperature, and ice structure. Salinities measured near zero at the surface, increasing to 3-4??? at the ice-water interface. Ice crystal texture was dominated by columnar ice, comprising 90% of the ice sampled. Surface albedos of various ice types, measured with radiometers, showed integrated shortwave albedos of 0.1 to 0.3 for melt ponds, 0.5 for bare, discolored ice, and 0.6 to 0.8 for a deteriorated surface or snow-covered ice. Aerial photography was utilized to document the distribution of open melt ponds, which decreased from 12% coverage of the ice surface in late July at 76??N to almost none in mid-August at 88??N. Most melt ponds were shallow, and depth bore no relationship to size. Sediment was pervasive from the southern Chukchi Sea to the north pole, occurring in bands or patches. It was absent in the Eurasian Arctic, where it had been observed on earlier expeditions. Calculations of reverse trajectories of the sediment-bearing floes suggest that the southernmost sediment was entrained during ice formation in the Beaufort Sea while more northerly samples probably originated in the East Siberian Sea, some as far west as the New Siberian Islands.

  2. Modelling sea ice dynamics

    Science.gov (United States)

    Murawski, Jens; Kleine, Eckhard

    2017-04-01

    Sea ice remains one of the frontiers of ocean modelling and is of vital importance for the correct forecasts of the northern oceans. At large scale, it is commonly considered a continuous medium whose dynamics is modelled in terms of continuum mechanics. Its specifics are a matter of constitutive behaviour which may be characterised as rigid-plastic. The new developed sea ice dynamic module bases on general principles and follows a systematic approach to the problem. Both drift field and stress field are modelled by a variational property. Rigidity is treated by Lagrangian relaxation. Thus one is led to a sensible numerical method. Modelling fast ice remains to be a challenge. It is understood that ridging and the formation of grounded ice keels plays a role in the process. The ice dynamic model includes a parameterisation of the stress associated with grounded ice keels. Shear against the grounded bottom contact might lead to plastic deformation and the loss of integrity. The numerical scheme involves a potentially large system of linear equations which is solved by pre-conditioned iteration. The entire algorithm consists of several components which result from decomposing the problem. The algorithm has been implemented and tested in practice.

  3. Controls on Arctic sea ice from first-year and multi-year survival rates

    Energy Technology Data Exchange (ETDEWEB)

    Hunke, Jes [Los Alamos National Laboratory

    2009-01-01

    The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi year ice. The transition to an Arctic that is populated by thinner first year sea ice has important implications for future trends in area and volume. Here we develop a reduced model for Arctic sea ice with which we investigate how the survivability of first year and multi year ice control the mean state, variability, and trends in ice area and volume.

  4. The missing Northern European winter cooling response to Arctic sea ice loss

    Science.gov (United States)

    Screen, James A.

    2017-01-01

    Reductions in Arctic sea ice may promote the negative phase of the North Atlantic Oscillation (NAO−). It has been argued that NAO-related variability can be used an as analogue to predict the effects of Arctic sea ice loss on mid-latitude weather. As NAO− events are associated with colder winters over Northern Europe, a negatively shifted NAO has been proposed as a dynamical pathway for Arctic sea ice loss to cause Northern European cooling. This study uses large-ensemble atmospheric simulations with prescribed ocean surface conditions to examine how seasonal-scale NAO− events are affected by Arctic sea ice loss. Despite an intensification of NAO− events, reflected by more prevalent easterly flow, sea ice loss does not lead to Northern European winter cooling and daily cold extremes actually decrease. The dynamical cooling from the changed NAO is ‘missing', because it is offset (or exceeded) by a thermodynamical effect owing to advection of warmer air masses. PMID:28262679

  5. Impact of declining Arctic sea ice on winter snowfall.

    Science.gov (United States)

    Liu, Jiping; Curry, Judith A; Wang, Huijun; Song, Mirong; Horton, Radley M

    2012-03-13

    While the Arctic region has been warming strongly in recent decades, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and east Asia. Here we demonstrate that the decrease in autumn Arctic sea ice area is linked to changes in the winter Northern Hemisphere atmospheric circulation that have some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in midlatitudes and clearly different interannual variability than the classical Arctic oscillation. This circulation change results in more frequent episodes of blocking patterns that lead to increased cold surges over large parts of northern continents. Moreover, the increase in atmospheric water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting increased heavy snowfall in Europe during early winter and the northeastern and midwestern United States during winter. We conclude that the recent decline of Arctic sea ice has played a critical role in recent cold and snowy winters.

  6. Global warming releases microplastic legacy frozen in Arctic Sea ice

    Science.gov (United States)

    Obbard, Rachel W.; Sadri, Saeed; Wong, Ying Qi; Khitun, Alexandra A.; Baker, Ian; Thompson, Richard C.

    2014-06-01

    When sea ice forms it scavenges and concentrates particulates from the water column, which then become trapped until the ice melts. In recent years, melting has led to record lows in Arctic Sea ice extent, the most recent in September 2012. Global climate models, such as that of Gregory et al. (2002), suggest that the decline in Arctic Sea ice volume (3.4% per decade) will actually exceed the decline in sea ice extent, something that Laxon et al. (2013) have shown supported by satellite data. The extent to which melting ice could release anthropogenic particulates back to the open ocean has not yet been examined. Here we show that Arctic Sea ice from remote locations contains concentrations of microplastics at least two orders of magnitude greater than those that have been previously reported in highly contaminated surface waters, such as those of the Pacific Gyre. Our findings indicate that microplastics have accumulated far from population centers and that polar sea ice represents a major historic global sink of man-made particulates. The potential for substantial quantities of legacy microplastic contamination to be released to the ocean as the ice melts therefore needs to be evaluated, as do the physical and toxicological effects of plastics on marine life.

  7. Arctic Summer Sea-Ice Extent: How Free is Free?

    Science.gov (United States)

    Tremblay, B.; Cullather, R. I.; DeRepentigny, P.; Pfirman, S. L.; Newton, R.

    2015-12-01

    As Northern Hemisphere perennial sea ice cover continues a long-term downward trend, attention has begun to focus on the implications of the changing conditions. A summertime ice-free Arctic Ocean is frequently indicated as a signature milestone for these changes, however "ice-free" has a substantially different meaning among scientists and interested stakeholders. To climate scientists it may mean when there is so little sea ice that it plays a minimal role in the climate system. To those interested in development, it may mean a threshold where icebreaker support is not required. To coastal communities it may mean so little ice that hunting is not possible. To species dependent on sea ice, it may mean the point where they cannot find sufficient habitat to survive from spring until fall. In this contribution we document the projected seasonality of the sea ice retreat and address the following questions. For how long will the Arctic Ocean be ice free on average each year? What is the impact of such changes in the seasonality of the sea ice cover on species that are dependent on sea ice? To this end, we analyze the seasonal cycle in the sea-ice extent simulated by the Community Earth System Model 1 - Large Ensemble (CESM1-LE) output for the 21st century. CESM1-LE simulates a realistic late 20th, early 21st century Arctic climate with a seasonal cycle in sea ice extent and rate of decline in good agreement with observations. Results from this model show that even by the end of the 21st century, the length of the ice-free season is relatively short, with ice-free conditions mainly present for 2-3 months between August and October. The result is a much larger amplitude seasonal cycle when compared with the late 20th century climate.

  8. The fate of lake ice in the North American Arctic

    Directory of Open Access Journals (Sweden)

    L. C. Brown

    2011-10-01

    Full Text Available Lakes comprise a large portion of the surface cover in northern North America, forming an important part of the cryosphere. The timing of lake ice phenological events (e.g. break-up/freeze-up is a useful indicator of climate variability and change, which is of particular relevance in environmentally sensitive areas such as the North American Arctic. Further alterations to the present day ice regime could result in major ecosystem changes, such as species shifts and the disappearance of perennial ice cover. The Canadian Lake Ice Model (CLIMo was used to simulate lake ice phenology across the North American Arctic from 1961–2100 using two climate scenarios produced by the Canadian Regional Climate Model (CRCM. Results from the 1961–1990 time period were validated using 15 locations across the Canadian Arctic, with both in situ ice cover observations from the Canadian Ice Database as well as additional ice cover simulations using nearby weather station data. Projected changes to the ice cover using the 30-year mean data between 1961–1990 and 2041–2070 suggest a shift in break-up and freeze-up dates for most areas ranging from 10–25 days earlier (break-up and 0–15 days later (freeze-up. The resulting ice cover durations show mainly a 10–25 day reduction for the shallower lakes (3 and 10 m and 10–30 day reduction for the deeper lakes (30 m. More extreme reductions of up to 60 days (excluding the loss of perennial ice cover were shown in the coastal regions compared to the interior continental areas. The mean maximum ice thickness was shown to decrease by 10–60 cm with no snow cover and 5–50 cm with snow cover on the ice. Snow ice was also shown to increase through most of the study area with the exception of the Alaskan coastal areas.

  9. Sea Ice Edge Location and Extent in the Russian Arctic, 1933-2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sea Ice Edge Location and Extent in the Russian Arctic, 1933-2006 data are derived from sea ice charts from the Arctic and Antarctic Research Institute (AARI),...

  10. Atmospheric dynamics: Arctic winds of change

    Science.gov (United States)

    Notz, Dirk

    2016-09-01

    The Earth's climate evolves in response to both externally forced changes and internal variability. Now research suggests that both drivers combine to set the pace of Arctic warming caused by large-scale sea-ice loss.

  11. Methane excess in Arctic surface water-triggered by sea ice formation and melting

    OpenAIRE

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-01-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence t...

  12. Arctic Ecosystem Integrated Survey (Arctic Eis): Marine ecosystem dynamics in the rapidly changing Pacific Arctic Gateway

    Science.gov (United States)

    Mueter, Franz J.; Weems, Jared; Farley, Edward V.; Sigler, Michael F.

    2017-01-01

    Arctic Marine Ecosystems are undergoing rapid changes associated with ice loss and surface warming resulting from human activities (IPCC, 2013). The most dramatic changes include an earlier ice retreat and a longer ice-free season, particularly on Arctic inflow shelves such as the Barents Sea in the Atlantic Arctic and the northern Bering Sea and Chukchi Sea in the Pacific Arctic, the two major gateways into the Arctic (Danielson et al., 2016; Frey et al., 2015; Serreze et al., 2007; Wood et al., 2015). The retreat of Arctic sea ice has opened access to the Arctic marine environment and its resources, particularly during summer, and among other changes has brought with it increased research activities. For the Pacific Arctic region, these activities have led to several recent compendiums examining physical, biogeochemical, and biological patterns and trends in this rapidly changing environment (Arrigo, 2015, 2016; Arrigo et al., 2014; Bluhm et al., 2010; Dunton et al., 2014; Grebmeier and Maslowski, 2014; Hopcroft and Day, 2013; Moore and Stabeno, 2015).

  13. Arctic sea ice thickness changes in terms of sea ice age

    Institute of Scientific and Technical Information of China (English)

    BI Haibo; FU Min; SUN Ke; LIU Yilin; XU Xiuli; HUANG Haijun

    2016-01-01

    In this study, changes in Arctic sea ice thickness for each ice age category were examined based on satellite observations and modelled results. Interannual changes obtained from Ice, Cloud, and Land Elevation Satellite (ICESat)-based results show a thickness reduction over perennial sea ice (ice that survives at least one melt season with an age of no less than 2 year) up to approximately 0.5–1.0 m and 0.6–0.8 m (depending on ice age) during the investigated winter and autumn ICESat periods, respectively. Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS)-based results provide a view of a continued thickness reduction over the past four decades. Compared to 1980s, there is a clear thickness drop of roughly 0.50 m in 2010s for perennial ice. This overall decrease in sea ice thickness can be in part attributed to the amplified warming climate in north latitudes. Besides, we figure out that strongly anomalous southerly summer surface winds may play an important role in prompting the thickness decline in perennial ice zone through transporting heat deposited in open water (primarily via albedo feedback) in Eurasian sector deep into a broader sea ice regime in central Arctic Ocean. This heat source is responsible for enhanced ice bottom melting, leading to further reduction in ice thickness.

  14. Does Arctic sea ice reduction foster shelf-basin exchange?

    Science.gov (United States)

    Ivanov, Vladimir; Watanabe, Eiji

    2013-12-01

    The recent shift in Arctic ice conditions from prevailing multi-year ice to first-year ice will presumably intensify fall-winter sea ice freezing and the associated salt flux to the underlying water column. Here, we conduct a dual modeling study whose results suggest that the predicted catastrophic consequences for the global thermohaline circulation (THC), as a result of the disappearance of Arctic sea ice, may not necessarily occur. In a warmer climate, the substantial fraction of dense water feeding the Greenland-Scotland overflow may form on Arctic shelves and cascade to the deep basin, thus replenishing dense water, which currently forms through open ocean convection in the sub-Arctic seas. We have used a simplified model for estimating how increased ice production influences shelf-basin exchange associated with dense water cascading. We have carried out case studies in two regions of the Arctic Ocean where cascading was observed in the past. The baseline range of buoyancy-forcing derived from the columnar ice formation was calculated as part of a 30-year experiment of the pan-Arctic coupled ice-ocean general circulation model (GCM). The GCM results indicate that mechanical sea ice divergence associated with lateral advection accounts for a significant part of the interannual variations in sea ice thermal production in the coastal polynya regions. This forcing was then rectified by taking into account sub-grid processes and used in a regional model with analytically prescribed bottom topography and vertical stratification in order to examine specific cascading conditions in the Pacific and Atlantic sectors of the Arctic Ocean. Our results demonstrate that the consequences of enhanced ice formation depend on geographical location and shelf-basin bathymetry. In the Pacific sector, strong density stratification in slope waters impedes noticeable deepening of shelf-origin water, even for the strongest forcing applied. In the Atlantic sector, a 1.5x increase of

  15. Arctic cyclone water vapor isotopes support past sea ice retreat recorded in Greenland ice

    OpenAIRE

    Eric S. Klein; J. E. Cherry; Young, J.; D. Noone; A. J. Leffler; Welker, J.M.

    2015-01-01

    Rapid Arctic warming is associated with important water cycle changes: sea ice loss, increasing atmospheric humidity, permafrost thaw, and water-induced ecosystem changes. Understanding these complex modern processes is critical to interpreting past hydrologic changes preserved in paleoclimate records and predicting future Arctic changes. Cyclones are a prevalent Arctic feature and water vapor isotope ratios during these events provide insights into modern hydrologic processes that help expla...

  16. Skill improvement of seasonal Arctic sea ice forecasts using bias-correction and ensemble calibration

    Science.gov (United States)

    Krikken, Folmer; Hazeleger, Wilco; Vlot, Willem; Schmeits, Maurice; Guemas, Virginie

    2016-04-01

    We explore the standard error and skill of dynamical seasonal sea ice forecasts of the Arctic using different bias-correction and ensemble calibration methods. The latter is often used in weather forecasting, but so far has not been applied to Arctic sea ice forecasts. We use seasonal predictions of Arctic sea ice of a 5-member ensemble forecast using the fully coupled GCM EC-Earth, with model initial states obtained by nudging towards ORAS4 and ERA-Interim. The raw model forecasts contain large biases in total sea ice area, especially during the summer months. This is mainly caused by a difference in average seasonal cycle between EC-Earth and observations, which translates directly into the forecasts yielding large biases. Further errors are introduced by the differences in long term trend between the observed sea ice, and the uninitialised EC-earth simulation. We find that extended logistic regression (ELR) and heteroscedastic extended logistic regression (HELR) both prove viable ensemble calibration methods, and improve the forecasts substantially compared to standard bias correction techniques. No clear distinction between ELR and HELR is found. Forecasts starting in May have higher skill (CRPSS > 0 up to 5 months lead time) than forecasts starting in August (2-3 months) and November (2-3 months), with trend-corrected climatology as reference. Analysis of regional skill in the Arctic shows distinct differences, where mainly the Arctic ocean and the Kara and Barents sea prove to be one of the more predictable regions with skilful forecasts starting in May up to 5-6 months lead time. Again, forecasts starting in August and November show much lower regional skill. Overall, it is still difficult to beat relative simple statistical forecasts, but by using ELR and HELR we are getting reasonably close to skilful seasonal forecasts up to 12 months lead time. These results show there is large potential, and need, for using ensemble calibration in seasonal forecasts of

  17. On the potential for abrupt Arctic winter sea-ice loss

    NARCIS (Netherlands)

    Bathiany, S.; Notz, Dirk; Mauritsen, T.; Raedel, G.; Brovkin, V.

    2016-01-01

    The authors examine the transition from a seasonally ice-covered Arctic to an Arctic Ocean that is sea ice free all year round under increasing atmospheric CO2 levels. It is shown that in comprehensive climate models, such loss of Arctic winter sea ice area is faster than the preceding loss of

  18. On the potential for abrupt Arctic winter sea-ice loss

    NARCIS (Netherlands)

    Bathiany, S.; Notz, Dirk; Mauritsen, T.; Raedel, G.; Brovkin, V.

    2016-01-01

    The authors examine the transition from a seasonally ice-covered Arctic to an Arctic Ocean that is sea ice free all year round under increasing atmospheric CO2 levels. It is shown that in comprehensive climate models, such loss of Arctic winter sea ice area is faster than the preceding loss of summe

  19. The Impact of Submarine Depth, Speed Sonar Systems on Arctic Sea-ice Draft Measurements

    Science.gov (United States)

    2015-04-21

    speed sonar systems on Arctic sea - ice draft measurements April 21, 2015 Reporting period: Oct 5, 2010- Sept 30, 2014 Prepared for: Office...TERM GOALS Arctic sea ice thickness is critical to geophysical research into climate change, shipping, biological productivity and other things...13. SUPPLEMENTARY NOTES 14. ABSTRACT Arctic sea ice thickness is critical to geophysical research into climate change, shipping, biological

  20. Large Decadal Decline of the Arctic Multiyear Ice Cover

    Science.gov (United States)

    Comiso, Josefino C.

    2012-01-01

    The perennial ice area was drastically reduced to 38% of its climatological average in 2007 but recovered slightly in 2008, 2009, and 2010 with the areas being 10%, 24%, and 11% higher than in 2007, respectively. However, trends in extent and area remained strongly negative at -12.2% and -13.5% decade (sup -1), respectively. The thick component of the perennial ice, called multiyear ice, as detected by satellite data during the winters of 1979-2011 was studied, and results reveal that the multiyear ice extent and area are declining at an even more rapid rate of -15.1% and -17.2% decade(sup -1), respectively, with a record low value in 2008 followed by higher values in 2009, 2010, and 2011. Such a high rate in the decline of the thick component of the Arctic ice cover means a reduction in the average ice thickness and an even more vulnerable perennial ice cover. The decline of the multiyear ice area from 2007 to 2008 was not as strong as that of the perennial ice area from 2006 to 2007, suggesting a strong role of second-year ice melt in the latter. The sea ice cover is shown to be strongly correlated with surface temperature, which is increasing at about 3 times the global average in the Arctic but appears weakly correlated with the Arctic Oscillation (AO), which controls the atmospheric circulation in the region. An 8-9-yr cycle is apparent in the multiyear ice record, which could explain, in part, the slight recovery in the last 3 yr.

  1. Fabric and crystal characteristics of Bohai and Arctic sea ice

    Institute of Scientific and Technical Information of China (English)

    李志军; 康建成; 蒲毅彬

    2002-01-01

    The fabrics and crystals of Bohai one-year ice show that the noncontinuous ice growth rate enables the level ice layers with different amount of air bubbles to be formed in lower part of an ice sheet which was clearly seen from CT technology; typical grain ice and columnar ice occur in the grey ice which grows in stable water; thaw-refrozen ice and rafted ice have their specific crystal characters. On the Arctic sea ice, the ice core located at 72°24.037′N, 153°33.994′W and 2.2 m in length was a 3-year ice floe and a new sort of crystal was found, which is defined as refrozen clastic pieces. The crystal profile of the ice core 4.86 m in length located at 74°58.614′N, 160°31.830′W shows the evidence that ice ridge changed into hummock.

  2. Correlated declines in Pacific arctic snow and sea ice cover

    Science.gov (United States)

    Stone, Robert P.; Douglas, David C.; Belchansky, Gennady I.; Drobot, Sheldon

    2005-01-01

    Simulations of future climate suggest that global warming will reduce Arctic snow and ice cover, resulting in decreased surface albedo (reflectivity). Lowering of the surface albedo leads to further warming by increasing solar absorption at the surface. This phenomenon is referred to as “temperature–albedo feedback.” Anticipation of such a feedback is one reason why scientists look to the Arctic for early indications of global warming. Much of the Arctic has warmed significantly. Northern Hemisphere snow cover has decreased, and sea ice has diminished in area and thickness. As reported in the Arctic Climate Impact Assessment in 2004, the trends are considered to be outside the range of natural variability, implicating global warming as an underlying cause. Changing climatic conditions in the high northern latitudes have influenced biogeochemical cycles on a broad scale. Warming has already affected the sea ice, the tundra, the plants, the animals, and the indigenous populations that depend on them. Changing annual cycles of snow and sea ice also affect sources and sinks of important greenhouse gases (such as carbon dioxide and methane), further complicating feedbacks involving the global budgets of these important constituents. For instance, thawing permafrost increases the extent of tundra wetlands and lakes, releasing greater amounts of methane into the atmosphere. Variable sea ice cover may affect the hemispheric carbon budget by altering the ocean–atmosphere exchange of carbon dioxide. There is growing concern that amplification of global warming in the Arctic will have far-reaching effects on lower latitude climate through these feedback mechanisms. Despite the diverse and convincing observational evidence that the Arctic environment is changing, it remains unclear whether these changes are anthropogenically forced or result from natural variations of the climate system. A better understanding of what controls the seasonal distributions of snow and ice

  3. Arctic sea ice decline contributes to thinning lake ice trend in northern Alaska

    Science.gov (United States)

    Alexeev, Vladimir; Arp, Christopher D.; Jones, Benjamin M.; Cai, Lei

    2016-01-01

    Field measurements, satellite observations, and models document a thinning trend in seasonal Arctic lake ice growth, causing a shift from bedfast to floating ice conditions. September sea ice concentrations in the Arctic Ocean since 1991 correlate well (r = +0.69,p sea ice affects lakes, we conducted model experiments to simulate winters with years of high (1991/92) and low (2007/08) sea ice extent for which we also had field measurements and satellite imagery characterizing lake ice conditions. A lake ice growth model forced with Weather Research and Forecasting model output produced a 7% decrease in lake ice growth when 2007/08 sea ice was imposed on 1991/92 climatology and a 9% increase in lake ice growth for the opposing experiment. Here, we clearly link early winter 'ocean-effect' snowfall and warming to reduced lake ice growth. Future reductions in sea ice extent will alter hydrological, biogeochemical, and habitat functioning of Arctic lakes and cause sub-lake permafrost thaw.

  4. Reversability of arctic sea ice retreat - A conceptual multi-scale modeling approach

    Science.gov (United States)

    Mueller-Stoffels, Marc

    The ice-albedo feedback has been identified as an important factor in the decay of the Arctic sea ice cover in a warming climate. Mechanisms of transition from perennial ice cover to seasonal ice cover are discussed in the literature; the existence of a tipping point is disputed. A newly developed regular network model for energy exchange and phase transition of an ice covered ocean mixed layer is introduced. The existence of bistability, a key ingredient for irreversibility, on local and regional scales is explored. It is shown in a spatially confined model that the asymptotic behavior and the existence of a parameter region of bistability strongly depend on the albedo parametrization. The spatial dynamics of sea ice retreat are studied for a high resolution latitudinal model of the ocean mixed layer. This regional model suggests that sea ice retreat is reversible. It is shown that laterally driven melt of thick multi-year sea ice, and thus, ice-albedo feedback, is an important mechanism in the transition from perennial to seasonal ice cover at the pole. Results are used to interpret observed changes in the recent ice extent and ice volume record. It is shown that the effectiveness of ice-albedo feedback strongly depends on the existence of lateral heat transfer mechanisms in the ocean.

  5. Quantification of the ice-cored moraines' short-term dynamics in the high-Arctic glaciers Ebbabreen and Ragnarbreen, Petuniabukta, Svalbard

    Science.gov (United States)

    Ewertowski, Marek W.; Tomczyk, Aleksandra M.

    2015-04-01

    Extensive ice-cored moraine complexes are common elements, marking the last advance of many Svalbard glaciers. Sediment gravity flows are among the most dynamic processes, transforming these landforms. The short-term (yearly and weekly) dynamics of mass-wasting processes were studied in a cm-scale using repetitive topographic scanning. We monitored several active sites on the forelands of two glaciers, Ebbabreen and Ragnarbreen, both of which are located near Petuniabukta at the northern end of Billefjorden in Spitsbergen. The surveys indicate high dynamic rates of landforms' transformation. The mean annual volume loss of sediments and dead-ice for the most active parts of the moraines was up to 1.8 m a- 1. However, most of the transformation occurred during summer, with the short-term values of mean elevation changes as high as - 104 mm day- 1. In comparison, the dynamics of the other (i.e. non-active) parts of the ice-cored moraines were much lower, namely, the mean annual lowering (attributed mainly to dead-ice downwasting) was up to 0.3 m a-1, whereas lowering during summer was up to 8 mm day- 1. Our results indicate that in the case of the studied glaciers, backwasting was much more effective than downwasting in terms of landscape transformation in the glacier forelands. However, despite the high activity of localised mass movement processes, the overall short-term dynamics of ice-cored moraines for the studied glaciers were relatively low. We suggest that as long as debris cover is sufficiently thick (thicker than the permafrost's active layer depths), the mass movement activity would occur only under specific topographic conditions and/or due to occurrence of external meltwater sources and slope undercutting. In other areas, ice-cored moraines remain a stable landsystem component in a yearly to decadal time-scale.

  6. Statistical indicators of Arctic sea-ice stability - prospects and limitations

    Science.gov (United States)

    Bathiany, Sebastian; van der Bolt, Bregje; Williamson, Mark S.; Lenton, Timothy M.; Scheffer, Marten; van Nes, Egbert H.; Notz, Dirk

    2016-07-01

    We examine the relationship between the mean and the variability of Arctic sea-ice coverage and volume in a large range of climates from globally ice-covered to globally ice-free conditions. Using a hierarchy of two column models and several comprehensive Earth system models, we consolidate the results of earlier studies and show that mechanisms found in simple models also dominate the interannual variability of Arctic sea ice in complex models. In contrast to predictions based on very idealised dynamical systems, we find a consistent and robust decrease of variance and autocorrelation of sea-ice volume before summer sea ice is lost. We attribute this to the fact that thinner ice can adjust more quickly to perturbations. Thereafter, the autocorrelation increases, mainly because it becomes dominated by the ocean water's large heat capacity when the ice-free season becomes longer. We show that these changes are robust to the nature and origin of climate variability in the models and do not depend on whether Arctic sea-ice loss occurs abruptly or irreversibly. We also show that our climate is changing too rapidly to detect reliable changes in autocorrelation of annual time series. Based on these results, the prospects of detecting statistical early warning signals before an abrupt sea-ice loss at a "tipping point" seem very limited. However, the robust relation between state and variability can be useful to build simple stochastic climate models and to make inferences about past and future sea-ice variability from only short observations or reconstructions.

  7. Intercomparison of passive microwave sea ice concentration retrievals over the high-concentration Arctic sea ice

    DEFF Research Database (Denmark)

    andersen, susanne; Tonboe, R.; Kaleschke, L.

    2007-01-01

    [1] Measurements of sea ice concentration from the Special Sensor Microwave Imager (SSM/I) using seven different algorithms are compared to ship observations, sea ice divergence estimates from the Radarsat Geophysical Processor System, and ice and water surface type classification of 59 wide......-swath synthetic aperture radar (SAR) scenes. The analysis is confined to the high-concentration Arctic sea ice, where the ice cover is near 100%. During winter the results indicate that the variability of the SSM/I concentration estimates is larger than the true variability of ice concentration. Results from...... a trusted subset of the SAR scenes across the central Arctic allow the separation of the ice concentration uncertainty due to emissivity variations and sensor noise from other error sources during the winter of 2003-2004. Depending on the algorithm, error standard deviations from 2.5 to 5.0% are found...

  8. The delivery of organic contaminants to the Arctic food web: Why sea ice matters

    DEFF Research Database (Denmark)

    Pucko, M.; Stern, Gary; Macdonald, Robie

    2015-01-01

    For decades sea ice has been perceived as a physical barrier for the loading of contaminants to the Arctic Ocean. We show that sea ice, in fact, facilitates the delivery of organic contaminants to the Arctic marine food web through processes that: 1) are independent of contaminant physical......–chemical properties (e.g. 2–3-fold increase in exposure to brine-associated biota), and 2) depend on physical–chemical properties and, therefore, differentiate between contaminants (e.g. atmospheric loading of contaminants to melt ponds over the summer, and their subsequent leakage to the ocean). We estimate...... the concentrations of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in melt pond water in the Beaufort Sea, Canadian High Arctic, in 2008, at near-gas exchange equilibriumbased on Henry's lawconstants (HLCs), air concentrations and exchange dynamics. CUPs currently present the highest...

  9. Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

    Science.gov (United States)

    Gradinger, Rolf; Bluhm, Bodil; Iken, Katrin

    2010-01-01

    The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate ( N=24-65 per station) 0.25 m 2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l -1 (median 0.8 ind l -1). In level ice, low ice algal pigment concentrations (3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of enhanced summer ice melt. Previous estimates of Arctic sea ice meiofauna and under-ice amphipods on regional and pan-Arctic scales likely underestimate abundances at least in summer because they typically do not include pressure ridges.

  10. Ice Mass Changes in the Russian High Arctic from Repeat High Resolution Topography.

    Science.gov (United States)

    Willis, Michael; Zheng, Whyjay; Pritchard, Matthew; Melkonian, Andrew; Morin, Paul; Porter, Claire; Howat, Ian; Noh, Myoung-Jong; Jeong, Seongsu

    2016-04-01

    We use a combination of ASTER and cartographically derived Digital Elevation Models (DEMs) supplemented with WorldView DEMs, the ArcticDEM and ICESat lidar returns to produce a time-series of ice changes occurring in the Russian High Arctic between the mid-20th century and the present. Glaciers on the western, Barents Sea coast of Novaya Zemlya are in a state of general retreat and thinning, while those on the eastern, Kara Sea coast are retreating at a slower rate. Franz Josef Land has a complicated pattern of thinning and thickening, although almost all the thinning is associated with rapid outlet glaciers feeding ice shelves. Severnaya Zemlya is also thinning in a complicated manner. A very rapid surging glacier is transferring mass into the ocean from the western periphery of the Vavilov Ice Cap on October Revolution Island, while glaciers feeding the former Matusevich Ice Shelf continue to thin at rates that are faster than those observed during the operational period of ICESat, between 2003 and 2009. Passive microwave studies indicate the total number of melt days is increasing in the Russian Arctic, although much of the melt may refreeze within the firn. It is likely that ice dynamic changes will drive mass loss for the immediate future. The sub-marine basins beneath several of the ice caps in the region suggest the possibility that mass loss rates may accelerate in the future.

  11. Spring Snow Depth on Arctic Sea Ice using the IceBridge Snow Depth Product (Invited)

    Science.gov (United States)

    Webster, M.; Rigor, I. G.; Nghiem, S. V.; Kurtz, N. T.; Farrell, S. L.

    2013-12-01

    Snow has dual roles in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from colder air temperatures, slowing its growth. From spring into summer, the albedo of snow determines how much insolation is transmitted through the sea ice and into the underlying ocean, ultimately impacting the progression of the summer ice melt. Knowing the snow thickness and distribution are essential for understanding and modeling sea ice thermodynamics and the surface heat budget. Therefore, an accurate assessment of the snow cover is necessary for identifying its impacts in the changing Arctic. This study assesses springtime snow conditions on Arctic sea ice using airborne snow thickness measurements from Operation IceBridge (2009-2012). The 2012 data were validated with coordinated in situ measurements taken in March 2012 during the BRomine, Ozone, and Mercury EXperiment field campaign. We find a statistically significant correlation coefficient of 0.59 and RMS error of 5.8 cm. The comparison between the IceBridge snow thickness product and the 1937, 1954-1991 Soviet drifting ice station data suggests that the snow cover has thinned by 33% in the western Arctic and 44% in the Beaufort and Chukchi Seas. A rudimentary estimation shows that a thinner snow cover in the Beaufort and Chukchi Seas translates to a mid-December surface heat flux as high as 81 W/m2 compared to 32 W/m2. The relationship between the 2009-2012 thinner snow depth distribution and later sea ice freeze-up is statistically significant, with a correlation coefficient of 0.59. These results may help us better understand the surface energy budget in the changing Arctic, and may improve our ability to predict the future state of the sea ice cover.

  12. Seasonal cycle of solar energy fluxes through Arctic sea ice

    Directory of Open Access Journals (Sweden)

    S. Arndt

    2014-06-01

    Full Text Available Arctic sea ice has not only decreased considerably during the last decades, but also changed its physical properties towards a thinner and more seasonal cover. These changes strongly impact the energy budget and might affect the ice-associated ecosystem of the Arctic. But until now, it is not possible to quantify shortwave energy fluxes through sea ice sufficiently well over large regions and during different seasons. Here, we present a new parameterization of light transmittance through sea ice for all seasons as a function of variable sea ice properties. The annual maximum solar heat flux of 30 × 105 J m−2 occurs in June, then also matching the under ice ocean heat flux. Furthermore, our results suggest that 96% of the total annual solar heat input occurs from May to August, during four months only. Applying the new parameterization on remote sensing and reanalysis data from 1979 to 2011, we find an increase in light transmission of 1.5% a−1 for all regions. Sensitivity studies reveal that the results strongly depend on the timing of melt onset and the correct classification of ice types. Hence, these parameters are of great importance for quantifying under-ice radiation fluxes and the uncertainty of this parameterization. Assuming a two weeks earlier melt onset, the annual budget increases by 20%. Continuing the observed transition from Arctic multi- to first year sea ice could increase light transmittance by another 18%. Furthermore, the increase in light transmission directly contributes to an increase in internal and bottom melt of sea ice, resulting in a positive transmittance-melt feedback process.

  13. Regional variability in sea ice melt in a changing Arctic.

    Science.gov (United States)

    Perovich, Donald K; Richter-Menge, Jacqueline A

    2015-07-13

    In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of 101 cm. The mean ice equivalent surface melt was 48 cm and the mean bottom melt was 53 cm. On average, surface melting decreases moving northward from the Beaufort Sea towards the North Pole; however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions, summer melting in the central Arctic is not large enough to completely remove the sea ice cover. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  14. Extreme low sea ice years in the Canadian Arctic Archipelago: 1998 versus 2007

    Science.gov (United States)

    Howell, Stephen E. L.; Tivy, Adrienne; Agnew, Tom; Markus, Thorsten; Derksen, Chris

    2010-10-01

    Extreme sea ice minima were observed within the Canadian Arctic Archipelago (CAA) during 1998 and 2007. The September average sea ice area was 2.90 and 2.65 standardized anomalies below the historical 1968-1996 climatology for 1998 and 2007, respectively. October sea ice area for 1998 was a staggering 4.45 standardized anomalies below the historical 1968-1996 climatology and 2007 was lower by 3.36 standardized anomalies. We examine the role of thermodynamic and dynamic forcing on CAA sea ice that was responsible for its extreme loss in 1998 and 2007. Thermodynamic forcing on the sea ice was concentrated over 1 month in 2007 facilitating rapid melt, contrasted against a long melt season in 1998. This variation was attributed to anomalously warm air temperatures in June, September, and October for 1998 compared to anomalously warm temperatures in July for 2007. Sea ice dynamics contributed to the 1998 minimum by inhibiting replenishment from the Arctic Ocean but actually facilitated replenishment in 2007 thereby preventing record low conditions. Replenishment was driven by dissimilarities in sea level pressure patterns over the CAA during these extreme years. Evidence for preconditioned thinning was apparent leading up to 2007 but not strongly apparent for 1998. Remarkably, at the onset of 1998 melt season, multi-year ice area within the CAA was 11% more than the historical climatology and 48% more than at the start of the 2007 melt season yet an extreme minima was still reached.

  15. Interplay between linear, dissipative and permanently critical mechanical processes in Arctic sea ice

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2010-08-01

    Full Text Available Mechanical processes in the Arctic ice pack result in fragmented sea ice cover, the regular geometry of which could be described in main features in terms of the conventional mechanics. However, the size distribution of sea ice floes does not exhibit the random (poissonian-like statistics and follows the power law typical for self-similar (fractal structures. The analysis of ice floe oscillations in the frequency range specific for cracking, shearing and stick-slip motion evidences the self-organized dynamics of sea ice fracturing, which manifests itself in scaling distributions of both the discrete energy discharges in fracture events and the recurrence times between that one. So determined space-time-energy self-similarity characterises the ice pack as the non-equilibrium, nonlinear thermodynamic system where the synergic relations are established through conventional long propagating wave/oscillations. The presented experimental data were collected at the Russian ice-research camp "North Pole 35" drifting on the Arctic ice pack in 2008.

  16. Analysis of WindSat Data over Arctic Sea Ice

    Science.gov (United States)

    The radiation of the 3rd and 4th Stokes components emitted by Arctic sea ice and observed by the spaceborne fully polarimetric radiometer WindSat is investigated. Two types of analysis are carried out, spatial (maps of different quadrants of azimuth look angles) and temporal (time series of daily av...

  17. Characterizing Arctic sea ice topography using high-resolution IceBridge data

    OpenAIRE

    Petty, Alek A.; Tsamados, Michel C.; Kurtz, Nathan T.; Farrell, Sinead L.; Newman, Thomas; Harbeck, Jeremy P.; FELTHAM, DANIEL L.; Richter-Menge, Jackie A.

    2015-01-01

    We present an analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009–2014 within the Beaufort/Chukchi and Central Arcti...

  18. Nonlinear threshold behavior during the loss of Arctic sea ice

    OpenAIRE

    Eisenman, I; Wettlaufer, J. S.

    2008-01-01

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or “tipping point”) beyond which the ice–albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice–albedo feedback. Here, we examine the central physical processes associated with the ...

  19. Arctic Warming and Sea Ice Diminution Herald Changing Glacier and Cryospheric Hazard Regimes

    Science.gov (United States)

    Kargel, Jeffrey; Bush, Andrew; Leonard, Gregory

    2013-04-01

    The recent expansion of summertime melt zones in both Greenland and some Arctic ice caps, and the clearing of perennial sea ice from much of the Arctic, may presage more rapid shifts in mass balances of land ice than glaciologists had generally expected. The summer openings of vast stretches of open water in the Arctic, particularly in straits and the Arctic Ocean shores of the Queen Elizabeth Islands and along some Greenland coastal zones, must have a large impact on summer and early autumn temperatures and precipitation now that the surface boundary condition is no longer limited by the triple-point temperature and water-vapor pressure of H2O. This state change in the Arctic probably is part of the explanation for the expanded melt zones high in the Greenland ice sheet. However, Greenland and the Canadian Arctic are vast regions subject to climatic influences of multiple marine bodies, and the situation with sea ice and climate change remains heterogeneous, and so the local climate feedbacks from sea ice diminution remain patchy. Projected forward just a few decades, it is likely that sea ice will play a significant role in the Queen Elizabeth Islands and around Greenland only in the winter months. The region is in the midst of a dramatic climate change that is affecting the mass balances of the Arctic's ice bodies; some polar-type glaciers must be transforming to polythermal, and polythermal ones to maritime-temperate types. Attendant with these shifts, glacier response times will shorten, the distribution and sizes of glacier lakes will change, unconsolidated debris will be debuttressed, and hazards-related dynamics will shift. Besides changes to outburst flood, debris flow, and rock avalanche occurrences, the tsunami hazard (with ice and debris landslide/avalanche triggers) in glacierized fjords and the surge behaviors of many glaciers is apt to increase or shift locations. For any given location, the past is no longer the key to the present, and the present

  20. The impact of under-ice melt ponds on Arctic sea ice volume

    Science.gov (United States)

    Smith, Naomi; Flocco, Daniela; Feltham, Daniel

    2016-04-01

    A one-dimensional, thermodynamic model of Arctic sea ice [Flocco et al, 2015] has been adapted to study the evolution of under-ice melt ponds, pools of fresh water that are found below the Arctic sea ice, and false bottoms, sheets of ice that form at the boundary between the under-ice melt pond and the oceanic mixed layer. Over time, either the under-ice melt pond freezes or the false bottom is completely ablated. We have been investigating the impact that these features have on the growth or ablation of sea ice during the time that they are present. The sensitivity of our model to a range of parameters has been tested, revealing some interesting effects of the thermodynamic processes taking place during the life-cycle of these phenomena. For example, the under-ice melt pond and its associated false bottom can insulate the sea ice layer from ocean, increasing the thickness of sea ice present at the end of the time frame considered. A comparison of the results of the model of under-ice melt pond evolution with that of sea ice with a bare base has been used to estimate the impact of under-ice melt ponds on sea ice volume towards the end of the melt season. We find that the under-ice melt ponds could have a significant impact on the mass balance of the sea ice, suggesting that it could be desirable to include a parameterisation of the effects of under-ice melt pond in the sea ice components of climate models.

  1. Seasonal Changes of Arctic Sea Ice Physical Properties Observed During N-ICE2015: An Overview

    Science.gov (United States)

    Gerland, S.; Spreen, G.; Granskog, M. A.; Divine, D.; Ehn, J. K.; Eltoft, T.; Gallet, J. C.; Haapala, J. J.; Hudson, S. R.; Hughes, N. E.; Itkin, P.; King, J.; Krumpen, T.; Kustov, V. Y.; Liston, G. E.; Mundy, C. J.; Nicolaus, M.; Pavlov, A.; Polashenski, C.; Provost, C.; Richter-Menge, J.; Rösel, A.; Sennechael, N.; Shestov, A.; Taskjelle, T.; Wilkinson, J.; Steen, H.

    2015-12-01

    Arctic sea ice is changing, and for improving the understanding of the cryosphere, data is needed to describe the status and processes controlling current seasonal sea ice growth, change and decay. We present preliminary results from in-situ observations on sea ice in the Arctic Basin north of Svalbard from January to June 2015. Over that time, the Norwegian research vessel «Lance» was moored to in total four ice floes, drifting with the sea ice and allowing an international group of scientists to conduct detailed research. Each drift lasted until the ship reached the marginal ice zone and ice started to break up, before moving further north and starting the next drift. The ship stayed within the area approximately 80°-83° N and 5°-25° E. While the expedition covered measurements in the atmosphere, the snow and sea ice system, and in the ocean, as well as biological studies, in this presentation we focus on physics of snow and sea ice. Different ice types could be investigated: young ice in refrozen leads, first year ice, and old ice. Snow surveys included regular snow pits with standardized measurements of physical properties and sampling. Snow and ice thickness were measured at stake fields, along transects with electromagnetics, and in drillholes. For quantifying ice physical properties and texture, ice cores were obtained regularly and analyzed. Optical properties of snow and ice were measured both with fixed installed radiometers, and from mobile systems, a sledge and an ROV. For six weeks, the surface topography was scanned with a ground LIDAR system. Spatial scales of surveys ranged from spot measurements to regional surveys from helicopter (ice thickness, photography) during two months of the expedition, and by means of an array of autonomous buoys in the region. Other regional information was obtained from SAR satellite imagery and from satellite based radar altimetry. The analysis of the data collected has started, and first results will be

  2. Late Holocene stable-isotope based winter temperature records from ice wedges in the Northeast Siberian Arctic

    Science.gov (United States)

    Opel, Thomas; Meyer, Hanno; Laepple, Thomas; Dereviagin, Alexander Yu.

    2016-04-01

    The Arctic is currently undergoing an unprecedented warming. This highly dynamic response on changes in climate forcing and the global impact of the Arctic water, carbon and energy balances make the Arctic a key region to study past, recent and future climate changes. Recent proxy-based temperature reconstructions indicate a long-term cooling over the past about 8 millennia that is mainly related to a decrease in solar summer insolation and has been reversed only by the ongoing warming. Climate model results on the other hand show no significant change or even a slight warming over this period. This model-proxy data mismatch might be caused by a summer bias of the used climate proxies. Ice wedges may provide essential information on past winter temperatures for a comprehensive seasonal picture of Holocene Arctic climate variability. Polygonal ice wedges are a widespread permafrost feature in the Arctic tundra lowlands. Ice wedges form by the repeated filling of thermal contraction cracks with snow melt water, which quickly refreezes at subzero ground temperatures and forms ice veins. As the seasonality of frost cracking and infill is generally related to winter and spring, respectively, the isotopic composition of wedge ice is indicative of past climate conditions during the annual cold season (DJFMAM, hereafter referred to as winter). δ18O of ice is interpreted as proxy for regional surface air temperature. AMS radiocarbon dating of organic remains in ice-wedge samples provides age information to generate chronologies for single ice wedges as well as regionally stacked records with an up to centennial resolution. In this contribution we seek to summarize Holocene ice-wedge δ18O based temperature information from the Northeast Siberian Arctic. We strongly focus on own work in the Laptev Sea region but consider as well literature data from other regional study sites. We consider the stable-isotope composition of wedge ice, ice-wedge dating and chronological

  3. Beyond Thin Ice: Co-Communicating the Many Arctics

    Science.gov (United States)

    Druckenmiller, M. L.; Francis, J. A.; Huntington, H.

    2015-12-01

    Science communication, typically defined as informing non-expert communities of societally relevant science, is persuaded by the magnitude and pace of scientific discoveries, as well as the urgency of societal issues wherein science may inform decisions. Perhaps nowhere is the connection between these facets stronger than in the marine and coastal Arctic where environmental change is driving advancements in our understanding of natural and socio-ecological systems while paving the way for a new assortment of arctic stakeholders, who generally lack adequate operational knowledge. As such, the Arctic provides opportunity to advance the role of science communication into a collaborative process of engagement and co-communication. To date, the communication of arctic change falls within four primary genres, each with particular audiences in mind. The New Arctic communicates an arctic of new stakeholders scampering to take advantage of unprecedented access. The Global Arctic conveys the Arctic's importance to the rest of the world, primarily as a regulator of lower-latitude climate and weather. The Intra-connected Arctic emphasizes the increasing awareness of the interplay between system components, such as between sea ice loss and marine food webs. The Transforming Arctic communicates the region's trajectory relative to the historical Arctic, acknowledging the impacts on indigenous peoples. The broad societal consensus on climate change in the Arctic as compared to other regions in the world underscores the opportunity for co-communication. Seizing this opportunity requires the science community's engagement with stakeholders and indigenous peoples to construct environmental change narratives that are meaningful to climate responses relative to non-ecological priorities (e.g., infrastructure, food availability, employment, or language). Co-communication fosters opportunities for new methods of and audiences for communication, the co-production of new interdisciplinary

  4. Contributing factors to an enhanced ice albedo feedback in Arctic sea ice

    Science.gov (United States)

    Perovich, D. K.; Jones, K. F.; Light, B.; Holland, M. M.

    2012-12-01

    The Arctic sea ice cover is in decline. In recent years there has been a decrease in summer ice area; a thinning of the ice cover; an increase in the amount of seasonal ice; an earlier onset of summer melt; and a later start of fall freeze up. Decreases in ice concentration substantially increase solar heat input to the ocean. Earlier dates of melt onset reduce ice albedo during a period when incident solar irradiance is large increasing solar heat input to the ice. Seasonal sea ice typically has a smaller albedo than perennial ice throughout the melt season. Thus, the observed shift to a seasonal ice cover causes greater solar heat input to the ice and more melting thereby accelerating ice decay. Thinner ice results in greater transmission of solar heat to the upper ocean, where it contributes to bottom melting, lateral melting, and warming of the water. All of these changes enhance the amount of solar energy deposited in the ice ocean system, and increasing ice melt. We will examine the relative magnitude of each of these changes individually as well as their collective contribution to the ice albedo feedback.

  5. Indicators of Arctic Sea Ice Bistability in Climate Model Simulations and Observations

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Indicators of Arctic Sea Ice Bistability in Climate...possibility that the climate system supports multiple Arctic sea ice states that are relevant for the evolution of sea ice during the next several...the most relevant scalar quantities related to the hemisphere-scale Arctic sea ice cover that indicate the presence of bistability, as well as the

  6. A recent bifurcation in Arctic sea-ice cover

    CERN Document Server

    Livina, Valerie N

    2012-01-01

    There is ongoing debate over whether Arctic sea-ice has already passed a 'tipping point', or whether it will do so in future, with several recent studies arguing that the loss of summer sea ice does not involve a bifurcation because it is highly reversible in models. Recently developed methods can detect and sometimes forewarn of bifurcations in time-series data, hence we applied them to satellite data for Arctic sea-ice cover. Here we show that a new low ice cover state has appeared from 2007 onwards, which is distinct from the normal state of seasonal sea ice variation, suggesting a bifurcation has occurred from one attractor to two. There was no robust early warning signal of critical slowing down prior to this bifurcation, consistent with it representing the appearance of a new ice cover state rather than the loss of stability of the existing state. The new low ice cover state has been sampled predominantly in summer-autumn and seasonal forcing combined with internal climate variability are likely respons...

  7. Relating Regional Arctic Sea Ice and climate extremes over Europe

    Science.gov (United States)

    Ionita-Scholz, Monica; Grosfeld, Klaus; Lohmann, Gerrit; Scholz, Patrick

    2016-04-01

    The potential increase of temperature extremes under climate change is a major threat to society, as temperature extremes have a deep impact on environment, hydrology, agriculture, society and economy. Hence, the analysis of the mechanisms underlying their occurrence, including their relationships with the large-scale atmospheric circulation and sea ice concentration, is of major importance. At the same time, the decline in Arctic sea ice cover during the last 30 years has been widely documented and it is clear that this change is having profound impacts at regional as well as planetary scale. As such, this study aims to investigate the relation between the autumn regional sea ice concentration variability and cold winters in Europe, as identified by the numbers of cold nights (TN10p), cold days (TX10p), ice days (ID) and consecutive frost days (CFD). We analyze the relationship between Arctic sea ice variation in autumn (September-October-November) averaged over eight different Arctic regions (Barents/Kara Seas, Beaufort Sea, Chukchi/Bering Seas, Central Arctic, Greenland Sea, Labrador Sea/Baffin Bay, Laptev/East Siberian Seas and Northern Hemisphere) and variations in atmospheric circulation and climate extreme indices in the following winter season over Europe using composite map analysis. Based on the composite map analysis it is shown that the response of the winter extreme temperatures over Europe is highly correlated/connected to changes in Arctic sea ice variability. However, this signal is not symmetrical for the case of high and low sea ice years. Moreover, the response of temperatures extreme over Europe to sea ice variability over the different Arctic regions differs substantially. The regions which have the strongest impact on the extreme winter temperature over Europe are: Barents/Kara Seas, Beaufort Sea, Central Arctic and the Northern Hemisphere. For the years of high sea ice concentration in the Barents/Kara Seas there is a reduction in the number

  8. Spatio-temporal Variability of Arctic Sea Ice from Days to Decades.

    Science.gov (United States)

    Wettlaufer, J. S.; Agarwal, S.

    2014-12-01

    We examine the daily satellite retrievals of Arctic sea-ice extent over three decades. The Arctic basin is divided into 14 different regions and we study how the Arctic wide observations emerge from these regional trends. In order to capture all possible time scales, the temporal dynamics within each spatial region, and in the basin as a whole, are treated as a multifractal. Our approach is Multi-Fractal Temporally Weighted Detrended Fluctuation Analysis (MF-TWDFA), which captures long time scales that are not accessible by standard DFA or MF-DFA and are by definition not part of a procedure that assumes the dynamics are described by an order one auto-regressive process. We examine how the eastern, western, central and the marginal seas control the longest time scales and what processes are responsible for the responses found in the data. Of particular interest is how regions with substantial seasonality contribute to the basin-wide dynamics of the system. The importance of this is intertwined with the general problem of how and when the Arctic may pass on to a state in which the ice cover is seasonal. The transition from a perennial state to a seasonal ice cover is the persistent state of affairs in the marginal regions of the ice cover, which constitute 10 of the 14 subregions, whereas the remaining 4 are in various stages of partial ice cover at various times of the year. In this manner, we use sub-basins as laboratories for the entire basin.

  9. Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation.

    Science.gov (United States)

    Jakobsson, Martin; Nilsson, Johan; Anderson, Leif; Backman, Jan; Björk, Göran; Cronin, Thomas M; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Barrientos Macho, Natalia; Cherniykh, Denis; Coxall, Helen; Eriksson, Björn; Flodén, Tom; Gemery, Laura; Gustafsson, Örjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

    2016-01-18

    The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼ 140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

  10. Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation

    Science.gov (United States)

    Jakobsson, Martin; Nilsson, Johan; Anderson, Leif G.; Backman, Jan; Bjork, Goran; Cronin, Thomas M.; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Macho, Natalia Barrientos; Cherniykh, Dennis; Coxall, Helen; Eriksson, Bjorn; Floden, Tom; Gemery, Laura; Gustafsson, Orjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

    2016-01-01

    The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (~140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

  11. Greenland Ice Sheet response to mid-Pliocene summer Arctic sea ice-free conditions

    Science.gov (United States)

    Koenig, S. J.; DeConto, R.; Pollard, D.

    2011-12-01

    A critical uncertainty in future predictions of climate and sea level is the response of the cryosphere. Proxy reconstructions for the mid-Pliocene Arctic Ocean (~ 3 Ma) are indicative of summer Arctic ice-free conditions and higher than modern sea surface temperatures, conditions that are analogous to projections for the end of the 21st century. We implement available mid-Pliocene boundary conditions into a fully-coupled Global Circulation Model with interactive vegetation. We use a 3-D thermo-mechanical ice sheet-shelf model to simulate the equilibrated response of the Greenland Ice Sheet (GIS) to the combined effect of reduced sea ice conditions and increased sea surface temperatures during the mid-Pliocene Warm Period. Reductions in Arctic sea ice are shown to enhance ocean/land-to-atmosphere fluxes, increasing heat and moisture transport in the high latitudes. In particular, changes in the North Atlantic exert a strong influence on the storm track and seasonal temperatures and precipitation over Greenland. Despite increased precipitation, warmer temperatures generally reduce snow mass balance. As a result, an initial present-day ice sheet forced by Pliocene climate undergoes rapid melting, limiting the ice sheet to the only highest elevations in South and East Greenland. Once the ice sheet is lost, local surface characteristics and associated feedbacks dominates Greenland climate, precluding the regrowth of the ice sheet. Depending on the initial state of the ice sheet, the equilibrated ice sheet loss is equivalent to between 5.8 to 6.4 m of sea level. We assess the sensitivity of the GIS to Pliocene forcing and internal feedbacks, adding to the understanding of land-ice sea-ice hysteresis in a world warmer than today.

  12. History of sea ice in the Arctic

    DEFF Research Database (Denmark)

    Polyak, Leonid; Alley, Richard B.; Andrews, John T.

    2010-01-01

    seasonally ice-free conditions occurred during warmer periods linked to orbital variations. The last low-ice event related to orbital forcing (high insolation) was in the early Holocene, after which the northern high latitudes cooled overall, with some superimposed shorterterm (multidecadal to millennial...

  13. The emergence of modern sea ice cover in the Arctic Ocean.

    Science.gov (United States)

    Knies, Jochen; Cabedo-Sanz, Patricia; Belt, Simon T; Baranwal, Soma; Fietz, Susanne; Rosell-Melé, Antoni

    2014-11-28

    Arctic sea ice coverage is shrinking in response to global climate change and summer ice-free conditions in the Arctic Ocean are predicted by the end of the century. The validity of this prediction could potentially be tested through the reconstruction of the climate of the Pliocene epoch (5.33-2.58 million years ago), an analogue of a future warmer Earth. Here we show that, in the Eurasian sector of the Arctic Ocean, ice-free conditions prevailed in the early Pliocene until sea ice expanded from the central Arctic Ocean for the first time ca. 4 million years ago. Amplified by a rise in topography in several regions of the Arctic and enhanced freshening of the Arctic Ocean, sea ice expanded progressively in response to positive ice-albedo feedback mechanisms. Sea ice reached its modern winter maximum extension for the first time during the culmination of the Northern Hemisphere glaciation, ca. 2.6 million years ago.

  14. The Arctic Ocean Perennial Ice Zone

    Science.gov (United States)

    Kwok, R.; Cunningham, G. F.; Yueh, S.

    1998-01-01

    This study shows that: 1) the NSCAT backscatter fields provide an estimate of the PIZ coverage of the Arctic Ocean; and, 2) the decrease in PIZ area over the winter gives an indication of the PIZ area exported through Fram Strait.

  15. Dipole anomaly in the Arctic atmosphere and winter Arctic sea ice motion

    Institute of Scientific and Technical Information of China (English)

    WU; Bingyi; ZHANG; Renhe

    2005-01-01

    This paper investigates a previously-ignored atmospheric circulation anomaly-di- pole structure anomaly in the arctic atmosphere, and its relationship with the winter sea ice motion, based on analyses of the International Arctic Buoy Programme Data (1979-1998) and datasets from the National Center for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) for the period of 1960-2002. The dipole structure anomaly is the second-leading mode of EOF of monthly mean SLP north of 70(N during the winter season (Oct.-Mar.), which accounts for 13% of the variance. One of its two anomaly centers is over the Canadian Archipelago; the other is situated over northern Eurasia and the Siberian marginal seas. Due to the dipole structure anomaly's strong meridionality, it becomes an important mechanism to drive both anomalous sea ice export out of the Arctic Basin and cold air outbreaks into the Barents Sea, the Nordic Seas and northern Europe.

  16. Greenland ice sheet initiation and Arctic sea ice coincide with Eocene and Oligocene CO2 changes

    Science.gov (United States)

    Tripati, Aradhna; Darby, Dennis

    2016-04-01

    Earth's modern ocean-climate system is largely defined by the presence of glacial ice on landmasses in both hemispheres. Northern Hemisphere ice was previously thought to have formed no earlier than the Miocene or Oligocene, about 20-30 million years after the widespread onset of Antarctic glaciation at the Eocene-Oligocene boundary. Controversially, the episodic presence of seasonal Arctic sea ice and glacial ice in the Northern Hemisphere beginning in the early Oligocene to Middle Eocene has been inferred from multiple observations. Here we use precise source determinations based on geochemical measurements of ice-rafted debris (IRD) from an ODP core in the Greenland Sea (75° N) to constrain glacial ice and sea ice-rafting in the Northern Hemisphere during the middle Eocene through early Oligocene. The chemical fingerprint of 2,334 detrital Fe oxide grains indicates most of these grains are from Greenland with >98% certainty. Thus the coarse IRD in the Greenland Sea originates from widespread areas of east Greenland as far south as the Denmark Strait area (~68° N), with additional IRD sources from the circum-Arctic Ocean. This is the first definitive evidence that mid-Eocene IRD in the Greenland Sea is from Greenland. Episodic glaciation of different source regions on Greenland is synchronous with times of ice-rafting in the western Arctic and ephemeral perennial Arctic ice cover. Intervals of bipolar glacial ice storage in the middle Eocene through early Oligocene coincide with evidence for periods of reduced CO2, associated with carbon cycle perturbations.

  17. Arctic Ocean sea ice drift origin derived from artificial radionuclides.

    Science.gov (United States)

    Cámara-Mor, P; Masqué, P; Garcia-Orellana, J; Cochran, J K; Mas, J L; Chamizo, E; Hanfland, C

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of (137)Cs and (239,240)Pu activities and the (240)Pu/(239)Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The (240)Pu/(239)Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the (240)Pu/(239)Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the (137)Cs and (239,240)Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  18. Arctic Sea Ice Simulation in the PlioMIP Ensemble

    Science.gov (United States)

    Howell, Fergus W.; Haywood, Alan M.; Otto-Bliesner, Bette L.; Bragg, Fran; Chan, Wing-Le; Chandler, Mark A.; Contoux, Camille; Kamae, Youichi; Abe-Ouchi, Ayako; Rosenbloom, Nan A.; Stepanek, Christian; Zhang, Zhongshi

    2016-01-01

    Eight general circulation models have simulated the mid-Pliocene warm period (mid-Pliocene, 3.264 to 3.025 Ma) as part of the Pliocene Modelling Intercomparison Project (PlioMIP). Here, we analyse and compare their simulation of Arctic sea ice for both the pre-industrial period and the mid-Pliocene. Mid-Pliocene sea ice thickness and extent is reduced, and the model spread of extent is more than twice the pre-industrial spread in some summer months. Half of the PlioMIP models simulate ice-free conditions in the mid-Pliocene. This spread amongst the ensemble is in line with the uncertainties amongst proxy reconstructions for mid-Pliocene sea ice extent. Correlations between mid-Pliocene Arctic temperatures and sea ice extents are almost twice as strong as the equivalent correlations for the pre-industrial simulations. The need for more comprehensive sea ice proxy data is highlighted, in order to better compare model performances.

  19. The uniaxial compressive strength of the Arctic summer sea ice

    Institute of Scientific and Technical Information of China (English)

    HAN Hongwei; LI Zhijun; HUANG Wenfeng; LU Peng; LEI Ruibo

    2015-01-01

    The results on the uniaxial compressive strength of Arctic summer sea ice are presented based on the sam-ples collected during the fifth Chinese National Arctic Research Expedition in 2012 (CHINARE-2012). Exper-imental studies were carried out at different testing temperatures (−3, −6 and −9°C), and vertical samples were loaded at stress rates ranging from 0.001 to 1 MPa/s. The temperature, density, and salinity of the ice were measured to calculate the total porosity of the ice. In order to study the effects of the total porosity and the density on the uniaxial compressive strength, the measured strengths for a narrow range of stress rates from 0.01 to 0.03 MPa/s were analyzed. The results show that the uniaxial compressive strength decreases linearly with increasing total porosity, and when the density was lower than 0.86 g/cm3, the uniaxial com-pressive strength increases in a power-law manner with density. The uniaxial compressive behavior of the Arctic summer sea ice is sensitive to the loading rate, and the peak uniaxial compressive strength is reached in the brittle-ductile transition range. The dependence of the strength on the temperature shows that the calculated average strength in the brittle-ductile transition range, which was considered as the peak uniaxial compressive strength, increases steadily in the temperature range from −3 to −9°C.

  20. Ice-Tethered Profiler Contributions to the Arctic Observing Network

    Science.gov (United States)

    Toole, J.; Krishfield, R.; Proshutinsky, A.; Timmermans, M.

    2008-12-01

    One of the hoped-for legacies of the International Polar Year is a sustained observational program such as the Arctic Observing Network to document and build understanding of future climate and ecosystem change. In the spirit of the now-operational international Argo float program, investigators from North America, Europe and Japan are collaborating to deploy drifting, ice-based observatory instrument systems on and below floes in the Arctic to sample the polar atmosphere-ice-ocean system and to make the resulting data available to researchers world-wide in real time. One element of these observatories is the WHOI Ice-Tethered Profiler, first deployed in August 2004. The ITP consists of a surface float and electronics package that sits atop an ice floe, a weighted, plastic-jacketed wire-rope tether extending from the surface float through the ice and down to 750-800 m depth, and a profiling vehicle with sensor package that moves up and down the tether. To date, 30 ITP systems (funded by research programs in 5 countries) have been deployed in the Arctic that together have returned more than 10,000 high-vertical-resolution temperature and salinity profiles spanning approximately 7 to 760 m depth over all seasons. Examples of the science being conducted with these data will be presented, along with performance statistics for the ITP instruments and engineering improvements/enhancements that are being implemented. Plans for sustaining the ITP contribution to the Arctic Observing Network will also be reviewed and future international collaborations invited.

  1. Wind waves in ice-free areas of Arctic seas.

    Science.gov (United States)

    Golubkin, Pavel; Chapron, Bertrand; Kudryavtsev, Vladimir

    Wind-generated waves in Kara, Laptev and East Siberian Seas are investigated using altimeter data from ENVISAT and SARAL-AltiKa. Only the “isolated” ice-free areas had been selected for analysis. In this case wind seas can be treated as pure wind-generated waves without any contamination by the swell. The isolated ice-free areas are identified using National Snow & Ice Data Center (NSIDC) ice concentration data generated from brightness temperatures derived from Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager/Sounder (SSMIS) on board the Defense Meteorological Satellite Program (DMSP) F13 and F17 satellites, respectively. The altimeter data, both significant wave height (SWH) and wind speed which were accompanied with ASCAT scatterometer wind velocity field (since 2007), have been selected for these areas in the time period 2002-2013. This data set is analyzed in terms of dimensionless SWH and dimensionless ice-free area. Either of these quantities is scaled using “standard” dimension analysis based on wind speed and gravity acceleration. Universal empirical dependences of dimensionless SWH on dimensionless ice-free areas are established. At smallest ice-free areas they are consistent with known universal dependences for wind wave generation at fetch limited conditions. At the largest ice-free areas the established dependences are consistent with field data for the open ocean conditions. Impact of climate change and ice melting in the Arctic areas on wind seas is discussed.

  2. Arctic sea ice area in CMIP3 and CMIP5 climate model ensembles - variability and change

    Science.gov (United States)

    Semenov, V. A.; Martin, T.; Behrens, L. K.; Latif, M.

    2015-02-01

    The shrinking Arctic sea ice cover observed during the last decades is probably the clearest manifestation of ongoing climate change. While climate models in general reproduce the sea ice retreat in the Arctic during the 20th century and simulate further sea ice area loss during the 21st century in response to anthropogenic forcing, the models suffer from large biases and the model results exhibit considerable spread. The last generation of climate models from World Climate Research Programme Coupled Model Intercomparison Project Phase 5 (CMIP5), when compared to the previous CMIP3 model ensemble and considering the whole Arctic, were found to be more consistent with the observed changes in sea ice extent during the recent decades. Some CMIP5 models project strongly accelerated (non-linear) sea ice loss during the first half of the 21st century. Here, complementary to previous studies, we compare results from CMIP3 and CMIP5 with respect to regional Arctic sea ice change. We focus on September and March sea ice. Sea ice area (SIA) variability, sea ice concentration (SIC) variability, and characteristics of the SIA seasonal cycle and interannual variability have been analysed for the whole Arctic, termed Entire Arctic, Central Arctic and Barents Sea. Further, the sensitivity of SIA changes to changes in Northern Hemisphere (NH) averaged temperature is investigated and several important dynamical links between SIA and natural climate variability involving the Atlantic Meridional Overturning Circulation (AMOC), North Atlantic Oscillation (NAO) and sea level pressure gradient (SLPG) in the western Barents Sea opening serving as an index of oceanic inflow to the Barents Sea are studied. The CMIP3 and CMIP5 models not only simulate a coherent decline of the Arctic SIA but also depict consistent changes in the SIA seasonal cycle and in the aforementioned dynamical links. The spatial patterns of SIC variability improve in the CMIP5 ensemble, particularly in summer. Both

  3. Arctic sea ice area changes in CMIP3 and CMIP5 climate models’ ensembles

    Directory of Open Access Journals (Sweden)

    V. A. Semenov

    2017-01-01

    Full Text Available The shrinking Arctic sea ice cover observed during the last decades is probably the clearest manifestation of ongoing climate change. While climate models in general reproduce the sea ice retreat in the Arctic during the 20th century and simulate further sea ice area loss during the 21st century in response to anthropogenic forcing, the models suffer from large biases and the results exhibit considerable spread. Here, we compare results from the two last generations of climate models, CMIP3 and CMIP5, with respect to total and regional Arctic sea ice change. Different characteristics of sea ice area (SIA in March and September have been analysed for the Entire Arctic, Central Arctic and Barents Sea. Further, the sensitivity of SIA to changes in Northern Hemisphere (NH temperature is investigated and dynamical links between SIA and some atmospheric variability modes are assessed.CMIP3 (SRES A1B and CMIP5 (RCP8.5 models not only simulate a coherent decline of the Arctic SIA but also depict consistent changes in the SIA seasonal cycle. The spatial patterns of SIC variability improve in CMIP5 ensemble, most noticeably in summer when compared to HadISST1 data. A better simulation of summer SIA in the Entire Arctic by CMIP5 models is accompanied by a slightly increased bias for winter season in comparison to CMIP3 ensemble. SIA in the Barents Sea is strongly overestimated by the majority of CMIP3 and CMIP5 models, and projected SIA changes are characterized by a high uncertainty. Both CMIP ensembles depict a significant link between the SIA and NH temperature changes indicating that a part of inter-ensemble SIA spread comes from different temperature sensitivity to anthropogenic forcing. The results suggest that, in general, a sensitivity of SIA to external forcing is enhanced in CMIP5 models. Arctic SIA interannual variability in the end of the 20th century is on average well simulated by both ensembles. To the end of the 21st century, September

  4. Consequences of future increased Arctic runoff on Arctic Ocean stratification, circulation, and sea ice cover

    Science.gov (United States)

    Nummelin, Aleksi; Ilicak, Mehmet; Li, Camille; Smedsrud, Lars H.

    2016-01-01

    The Arctic Ocean has important freshwater sources including river runoff, low evaporation, and exchange with the Pacific Ocean. In the future, we expect even larger freshwater input as the global hydrological cycle accelerates, increasing high-latitude precipitation, and river runoff. Previous modeling studies show some robust responses to high-latitude freshwater perturbations, including a strengthening of Arctic stratification and a weakening of the large-scale ocean circulation; some idealized modeling studies also document a stronger cyclonic circulation within the Arctic Ocean itself. With the broad range of scales and processes involved, the overall effect of increasing runoff requires an understanding of both the local processes and the broader linkages between the Arctic and surrounding oceans. Here we adopt a more comprehensive modeling approach by increasing river runoff to the Arctic Ocean in a coupled ice-ocean general circulation model, and show contrasting responses in the polar and subpolar regions. Within the Arctic, the stratification strengthens, the halocline and Atlantic Water layer warm, and the cyclonic circulation spins up, in agreement with previous work. In the subpolar North Atlantic, the model simulates a colder and fresher water column with weaker barotropic circulation. In contrast to the estuarine circulation theory, the volume exchange between the Arctic Ocean and the surrounding oceans does not increase with increasing runoff. While these results are robust in our model, we require experiments with other model systems and more complete observational syntheses to better constrain the sensitivity of the climate system to high-latitude freshwater perturbations.

  5. The delivery of organic contaminants to the Arctic food web: why sea ice matters.

    Science.gov (United States)

    Pućko, Monika; Stern, Gary A; Macdonald, Robie W; Jantunen, Liisa M; Bidleman, Terry F; Wong, Fiona; Barber, David G; Rysgaard, Søren

    2015-02-15

    For decades sea ice has been perceived as a physical barrier for the loading of contaminants to the Arctic Ocean. We show that sea ice, in fact, facilitates the delivery of organic contaminants to the Arctic marine food web through processes that: 1) are independent of contaminant physical-chemical properties (e.g. 2-3-fold increase in exposure to brine-associated biota), and 2) depend on physical-chemical properties and, therefore, differentiate between contaminants (e.g. atmospheric loading of contaminants to melt ponds over the summer, and their subsequent leakage to the ocean). We estimate the concentrations of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in melt pond water in the Beaufort Sea, Canadian High Arctic, in 2008, at near-gas exchange equilibrium based on Henry's law constants (HLCs), air concentrations and exchange dynamics. CUPs currently present the highest risk of increased exposures through melt pond loading and drainage due to the high ratio of melt pond water to seawater concentration (Melt pond Enrichment Factor, MEF), which ranges from 2 for dacthal to 10 for endosulfan I. Melt pond contaminant enrichment can be perceived as a hypothetical 'pump' delivering contaminants from the atmosphere to the ocean under ice-covered conditions, with 2-10% of CUPs annually entering the Beaufort Sea via this input route compared to the standing stock in the Polar Mixed Layer of the ocean. The abovementioned processes are strongly favored in first-year ice compared to multi-year ice and, therefore, the dynamic balance between contaminant inventories and contaminant deposition to the surface ocean is being widely affected by the large-scale icescape transition taking place in the Arctic.

  6. Dissolved organic carbon (DOC in Arctic ground ice

    Directory of Open Access Journals (Sweden)

    M. Fritz

    2015-01-01

    Full Text Available Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC and nutrients which have been accumulated in late Pleistocene and Holocene unconsolidated deposits. Their vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change is largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC, dissolved inorganic carbon (DIC and other elements, which are important for ecosystems and carbon cycling. Here we show, using geochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage with a maximum of 28.6 mg L−1 (mean: 9.6 mg L−1. Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly stored in ground ice, especially in ice wedges, even before further degradation. In the Yedoma region ice wedges represent a significant DOC (45.2 Tg and DIC (33.6 Tg pool in permafrost areas and a fresh-water reservoir of 4172 km3. This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost carbon pool for ecosystems and climate feedback upon mobilization.

  7. Arctic sea ice response to atmospheric forcings with varying levels of anthropogenic warming and climate variability

    Science.gov (United States)

    Zhang, Jinlun; Steele, Michael; Schweiger, Axel

    2010-10-01

    Numerical experiments are conducted to project arctic sea ice responses to varying levels of future anthropogenic warming and climate variability over 2010-2050. A summer ice-free Arctic Ocean is likely by the mid-2040s if arctic surface air temperature (SAT) increases 4°C by 2050 and climate variability is similar to the past relatively warm two decades. If such a SAT increase is reduced by one-half or if a future Arctic experiences a range of SAT fluctuation similar to the past five decades, a summer ice-free Arctic Ocean would be unlikely before 2050. If SAT increases 4°C by 2050, summer ice volume decreases to very low levels (10-37% of the 1978-2009 summer mean) as early as 2025 and remains low in the following years, while summer ice extent continues to fluctuate annually. Summer ice volume may be more sensitive to warming while summer ice extent more sensitive to climate variability. The rate of annual mean ice volume decrease relaxes approaching 2050. This is because, while increasing SAT increases summer ice melt, a thinner ice cover increases winter ice growth. A thinner ice cover also results in a reduced ice export, which helps to further slow ice volume loss. Because of enhanced winter ice growth, arctic winter ice extent remains nearly stable and therefore appears to be a less sensitive climate indicator.

  8. Arctic energy budget in relation to sea ice variability on monthly-to-annual time scales

    NARCIS (Netherlands)

    Krikken, F.; Hazeleger, W.

    2015-01-01

    The large decrease in Arctic sea ice in recent years has triggered a strong interest in Arctic sea ice predictions on seasonal-to-decadal time scales. Hence, it is important to understand physical processes that provide enhanced predictability beyond persistence of sea ice anomalies. This study

  9. Arctic energy budget in relation to sea ice variability on monthly-to-annual time scales

    NARCIS (Netherlands)

    Krikken, F.; Hazeleger, W.

    2015-01-01

    The large decrease in Arctic sea ice in recent years has triggered a strong interest in Arctic sea ice predictions on seasonal-to-decadal time scales. Hence, it is important to understand physical processes that provide enhanced predictability beyond persistence of sea ice anomalies. This study anal

  10. Acoustic Scattering Kernels from Arctic Sea Ice.

    Science.gov (United States)

    1986-10-01

    84-C-0180 S. PErfORMING ORGANIZATION NAME AND AOMRSSS 10. PROGRAM ELEMENT. PROJECT . TASK Science Applications International Corp. AREA & WORK UNIT...al. (1986) described an implementation of SISM/ICE for the ASTRAL and PE models. The concepts are also relevant to other models, including FACT, FFP...Even if the ice field contains keels of only a single size, the projected keel width intercepted by any particular track will take on a range of

  11. The Impact of a Lower Sea Ice Extent on Arctic Greenhouse Gas Exchange

    Science.gov (United States)

    Parmentier, Frans-Jan W.; Christensen, Torben R.; Lotte Sørensen, Lise; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.

    2013-04-01

    years has the potential to influence greenhouse gas exchange across terrestrial ecosystems and the Arctic Ocean, but the overall impact remains unclear. In this study, we therefore try to reduce this uncertainty by addressing the influence of the decline in sea ice extent on all affected greenhouse gas fluxes in the high latitudes. Also, we will address the need for more research, on the ocean and on the land, to understand the impact of a lower sea ice extent on Arctic greenhouse gas exchange. References: Bates, N. R., Moran, S. B., Hansell, D. A. and Mathis, J. T.: An increasing CO2 sink in the Arctic Ocean due to sea-ice loss, Geophys. Res. Lett., 33, L23609, doi:10.1029/2006GL027028, 2006. Cai, W.-J., Chen, L., Chen, B., Gao, Z., Lee, S. H., Chen, J., Pierrot, D., Sullivan, K., Wang, Y., Hu, X., Huang, W.-J., et al.: Decrease in the CO2 Uptake Capacity in an Ice-Free Arctic Ocean Basin, Science, 329(5991), 556-559, doi:10.1126/science.1189338, 2010. Kort, E. A., Wofsy, S. C., Daube, B. C., Diao, M., Elkins, J. W., Gao, R. S., Hintsa, E. J., Hurst, D. F., Jimenez, R., Moore, F. L., Spackman, J. R., et al.: Atmospheric observations of Arctic Ocean methane emissions up to 82 degrees north, Nature Geosci., 5(5), 318-321, doi:10.1038/NGEO1452, 2012. Nomura, D., Yoshikawa-Inoue, H. and Toyota, T.: The effect of sea-ice growth on air-sea CO2 flux in a tank experiment, vol. 58, pp. 418-426. 2006. Post, E., Forchhammer, M. C., Bret-Harte, M. S., Callaghan, T. V., Christensen, T. R., Elberling, B., Fox, A. D., Gilg, O., Hik, D. S., Høye, T. T., Ims, R. A., et al.: Ecological Dynamics Across the Arctic Associated with Recent Climate Change, Science, 325(5946), 1355-1358, doi:10.1126/science.1173113, 2009. Rysgaard, S., Glud, R. N., Sejr, M. K., Bendtsen, J. and Christensen, P. B.: Inorganic carbon transport during sea ice growth and decay: A carbon pump in polar seas, J. Geophys. Res., 112, C03016, doi:10.1029/2006JC003572, 2007. Schuur, E. A. G., Abbott, B. and Network, P. C

  12. Peopling of the high Arctic - induced by sea ice?

    Science.gov (United States)

    Funder, Svend

    2010-05-01

    'We travelled in the winter after the return of daylight and did not go into fixed camp until spring, when the ice broke up. There was good hunting on the way, seals, beluga, walrus, bear.' (From Old Merkrusârk's account of his childhood's trek from Baffin Island to Northwest Greenland, told to Knud Rasmussen on Saunders Island in 1904) Five thousand years ago people moving eastwards from Beringia spread over the barrens of the Canadian high Arctic. This was the first of three waves of prehistoric Arctic 'cultures', which eventually reached Greenland. The passage into Greenland has to go through the northernmost and most hostile part of the country with a 5 month Polar night, and to understand this extraordinary example of human behaviour and endurance, it has been customary to invoke a more favourable (warmer) climate. This presentation suggests that land-fast sea ice, i.e. stationary sea ice anchored to the coast, is among the most important environmental factors behind the spread of prehistoric polar cultures. The ice provides the road for travelling and social communion - and access to the most important source of food, the ocean. In the LongTerm Project (2006 and 2007) we attempted to establish a Holocene record for sea ice variations along oceanic coasts in northernmost Greenland. Presently the coasts north of 80° N are beleaguered by year-round sea ice - for ten months this is land-fast ice, and only for a period in the stormy autumn months are the coasts exposed to pack-ice. This presentation Land-fast ice - as opposed to pack-ice - is a product of local temperatures, but its duration over the year, and especially into the daylight season, is also conditioned by other factors, notably wind strength. In the geological record we recognize long lasting land-fast ice by two absences: absence of traces of wave action (no beach formation), which, however, can also be a result of pack-ice along the coast; - and absence of driftwood on the shore (land-fast ice

  13. Reconstructing sea ice conditions in the Arctic and sub-Arctic prior to human observations

    Science.gov (United States)

    de Vernal, Anne; Hillaire-Marcel, Claude; Solignac, Sandrine; Radi, Taoufik; Rochon, André

    Sea ice is a sensitive parameter characterized by a high variability in space and time that can be reconstructed from paleoclimatological archives. The most direct indication of past sea ice cover is found in marine sediments, which contain various tracers or proxies of environments characterized by sea ice. They include sedimentary tracers of particles entrained and dispersed by sea ice, biogenic remains associated with production under/within sea ice or with ice-free conditions, in addition to geochemical and isotopic tracers of brine formation linked to sea ice growth. Reconstructing the extent of past sea ice is, however, difficult because proxies are only indirectly related to sea ice and require the use of transfer functions having inherent uncertainties. In particular, we have to assume a correspondence between sea ice cover values from modern observations and the sea ice proxies from surface sediment samples, which is a source of bias since the time intervals represented by modern observations (here 1954-2000) and surface sediments (100-103 years) are not equivalent. Moreover, suitable sedimentary sequences for reconstructing sea ice are rare, making the spatial resolution of reconstructions very patchy. Nevertheless, although fragmentary in time and space and despite uncertainties, available reconstructions reveal very large amplitude changes of sea ice in response to natural forcing during the recent geological past. For example, during the early Holocene, about 8000 years ago, data from dinocyst assemblages suggest reduced sea ice cover as compared to present in some subarctic basins (Labrador Sea, Baffin Bay, and Hudson Bay), whereas enhanced sea ice cover is reconstructed along the eastern Greenland margin and in the western Arctic, showing a pattern not unlike the dipole anomaly that was observed during the 20th century.

  14. Acquisition of Ice Thickness and Ice Surface Characteristics in the Seasonal Ice Zone by CULPIS-X during the US Coast Guard’s Arctic Domain Awareness Program

    Science.gov (United States)

    2014-09-30

    Characteristics in the Seasonal Ice Zone by CULPIS-X during the US Coast Guard’s Arctic Domain Awareness Program Year 3 Report PI: Mark A. Tschudi...surface temperature? During summer, melting ice is covered extensively by melt ponds, which exhibit a reflectance considerably lower than the...of Ice Thickness and Ice Surface Characteristics in the Seasonal Ice Zone by CULPIS-X during the US Coast Guard’s Arctic Domain Awareness Program 5a

  15. Atmospheric Response to Variations in Arctic Sea Ice Conditions

    Science.gov (United States)

    Bhatt, U.; Alexander, M.; Walsh, J.; Timlin, M.; Miller, J.

    2001-12-01

    While it is generally accepted that changes in air temperature and circulation determine sea ice conditions, it is not understood how the atmosphere is influenced by changes in sea ice. We employ the NCAR CCM 3.6 with specified ice extent and sea surface temperatures (sst). The overarching question addressed in this study is: how do variations in sea ice influence the atmosphere? We are particularly interested in the summer time response to highlight this unique aspect of this research. A control experiment has been integrated for 55 years by repeating the mean annual cycle of observed sea ice extent (either 0% or 100% ice cover) and sst, based on the period 1979-99. Sets of 50 member ensemble experiments were constructed by integrating the CCM from October to April using climatological sst (same as control) and observed sea ice extent from the winters of 1982-83 (ice maximum) and 1995-96 (ice minimum). Similar summertime sensitivity experiments were performed using ice extent conditions from April to October during 1982 (maximum) and 1995 (minimum). While responses were found both in winter and summer, the results described below refer to the summer of 1995. A set of 50 ensembles was also integrated for the summer of 1995 using sea ice concentration instead of extent. During the summer of 1995, negative sea ice anomalies were particularly large in the Siberian Arctic. Sea ice reductions result in increased surface and air temperatures and enhanced latent, sensible, and longwave fluxes out of the ocean. However, the net heat flux out of the ocean decreases because the changes are dominated by increased absorption of solar radiation over the low-albedo ocean. Cloud feedbacks are important in the Arctic and the downwelling solar at the surface decreases. The total cloud amount decreases due to reductions in low level clouds, however, convective cloud amounts increased. The net cloud radiative (shortwave and longwave) forcing is smaller in the experiment than the

  16. Ecosystem model intercomparison of under-ice and total primary production in the Arctic Ocean

    OpenAIRE

    Jin, Meibing; Popova, Ekaterina E.; Zhang, Jinlun; Ji, Rubao; Pendleton, Daniel; Varpe, Øystein; Yool, Andrew; Lee, Younjoo J.

    2016-01-01

    Previous observational studies have found increasing primary production (PP) in response to declining sea ice cover in the Arctic Ocean. In this study, under-ice PP was assessed based on three coupled ice-ocean-ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project. All models showed good agreement with under-ice measurements of surface chlorophyll-a concentration and vertically integrated PP rates during the main under-ice production perio...

  17. Abnormal Winter Melting of the Arctic Sea Ice Cap Observed by the Spaceborne Passive Microwave Sensors

    Science.gov (United States)

    Lee, Seongsuk; Yi, Yu

    2016-12-01

    The spatial size and variation of Arctic sea ice play an important role in Earth’s climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/ or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).

  18. Influence of ice thickness and surface properties on light transmission through Arctic sea ice

    Science.gov (United States)

    Katlein, Christian; Arndt, Stefanie; Nicolaus, Marcel; Perovich, Donald K.; Jakuba, Michael V.; Suman, Stefano; Elliott, Stephen; Whitcomb, Louis L.; McFarland, Christopher J.; Gerdes, Rüdiger; Boetius, Antje; German, Christopher R.

    2015-09-01

    The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy budget of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy in the upper ocean and thus plays a crucial role for amount and timing of sea-ice-melt and under-ice primary production. Recent developments in underwater technology provide new opportunities to study light transmission below the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance using the new Nereid Under-Ice (NUI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. NUI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely piloted and autonomous surveys underneath land-fast and moving sea ice. Here we present results from one of the first comprehensive scientific dives of NUI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three dimensional under-ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties on the spatial variability of light transmittance during summer. Our results show that surface properties such as melt ponds dominate the spatial distribution of the under-ice light field on small scales (<1000 m2), while sea ice-thickness is the most important predictor for light transmission on larger scales. In addition, we propose the use of an algorithm to obtain histograms of light transmission from distributions of sea ice thickness and surface albedo.

  19. Influence of ice thickness and surface properties on light transmission through Arctic sea ice

    Science.gov (United States)

    Katlein, C.; Arndt, S.; Nicolaus, M.; Perovich, D. K.; Jakuba, M.; Suman, S.; Elliott, S.; Whitcomb, L. L.; McFarland, C.; Gerdes, R.; Boetius, A.

    2015-12-01

    The changes in physical properties of sea ice such as decreased thickness and increased melt pond cover observed over the last decades severely impact the energy budget of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy in the upper ocean and thus plays a crucial role in the amount and timing of sea-ice-melt and under-ice primary production. Recent developments in underwater technology provide new opportunities to undertake challenging research at the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance onboard the new Nereid Under-Ice (NUI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. NUI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely-piloted and autonomous surveys underneath land-fast and moving sea ice. Here we present results from one of the first comprehensive scientific dives of NUI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three-dimensional under-ice topography and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties during summer on the spatial variability of light transmittance. Results show that surface properties dominate the spatial distribution of the under-ice light field on small scales (<1000m²), while sea ice-thickness is the most important predictor for light transmission on larger scales. In addition, we suggest an algorithm to obtain histograms of light transmission from distributions of sea ice thickness and surface albedo.

  20. Influence of ice thickness and surface properties on light transmission through Arctic sea ice.

    Science.gov (United States)

    Katlein, Christian; Arndt, Stefanie; Nicolaus, Marcel; Perovich, Donald K; Jakuba, Michael V; Suman, Stefano; Elliott, Stephen; Whitcomb, Louis L; McFarland, Christopher J; Gerdes, Rüdiger; Boetius, Antje; German, Christopher R

    2015-09-01

    The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy budget of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy in the upper ocean and thus plays a crucial role for amount and timing of sea-ice-melt and under-ice primary production. Recent developments in underwater technology provide new opportunities to study light transmission below the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance using the new Nereid Under-Ice (NUI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. NUI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely piloted and autonomous surveys underneath land-fast and moving sea ice. Here we present results from one of the first comprehensive scientific dives of NUI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three dimensional under-ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties on the spatial variability of light transmittance during summer. Our results show that surface properties such as melt ponds dominate the spatial distribution of the under-ice light field on small scales (ice-thickness is the most important predictor for light transmission on larger scales. In addition, we propose the use of an algorithm to obtain histograms of light transmission from distributions of sea ice thickness and surface albedo.

  1. Weakening of the stratospheric polar vortex by Arctic sea-ice loss.

    Science.gov (United States)

    Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

    2014-09-02

    Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

  2. Arctic ice core records of vanillic acid from Siberia, Greenland, and Svalbard

    Science.gov (United States)

    Grieman, M. M.; Saltzman, E. S.; McConnell, J.; Fritzsche, D.; Opel, T.; Isaksson, E. D.; Schwikowski, M.

    2015-12-01

    Biomass burning is a major source for atmospheric gases and aerosols, and an important part of the global carbon cycle and radiation budget. The factors controlling centennial and millennial variability in regional to global biomass burning dynamics are not well understood because there are few well-dated proxy records only. We are exploring ice core records of organic compounds resulting from incomplete combustion of lignin as tracers for biomass burning. In this study we investigate the distribution of vanillic acid (VA) in Arctic ice cores. VA is a major product of conifer combustion, but may also be produced from angiosperms. VA was measured in ice core samples using ion chromatography with electrospray MS/MS detection. Here we present measurements of vanillic acid in three Arctic ice cores from Siberia (Akademii Nauk; 0-3 kyr bp), northern Greenland (Tunu; 0-1.75 kyr bp), and Svalbard (Lomonosovfonna; 0-0.75 kyr bp). The Siberian record exhibits 3 strong centennial scale maxima (1200-600 BC, AD 300-800, and AD 1450-1700). All three cores exhibit a smaller feature around 1250, with a subsequent decline in Greenland and Svalbard. VA levels in Greenland and Svalbard are generally smaller than those in Siberia. These results suggest strong regional input from Northern Eurasian sources (i.e. boreal forests) to the Siberian core, and lower Arctic-wide "background" levels at the other sites.

  3. Ice Complex formation in arctic East Siberia during the MIS3 Interstadial

    Science.gov (United States)

    Wetterich, Sebastian; Tumskoy, Vladimir; Rudaya, Natalia; Andreev, Andrei A.; Opel, Thomas; Meyer, Hanno; Schirrmeister, Lutz; Hüls, Matthias

    2014-01-01

    A continuous 15 m long sequence of Ice Complex permafrost (Yedoma) exposed in a thermo-cirque at the southern coast of Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Dmitry Laptev Strait) was studied to reconstruct past landscape and environmental dynamics. The sequence accumulated during the Marine Isotope Stage 3 (MIS3) Interstadial between >49 and 29 ka BP in an ice-wedge polygon. The frozen deposits were cryolithologically described and sampled on a vertical bluff between two ice wedges. According to sedimentological and geochronological data, the section is subdivided into three units which correlate with environmental conditions of the early, middle, and late MIS3 period. Palynological data support this stratification. The stable isotope signature of texture ice in the polygon structure reflects fractionation due to local freeze-thaw processes, while the signature of an approximately 5 m wide and more than 17 m high ice wedge fits very well into the regional stable-water isotope record. Regional climate dynamics during the MIS3 Interstadial and local landscape conditions of the polygonal patterned ground controlled the Ice Complex formation. The sequence presented here completes previously published MIS3 permafrost records in Northeast Siberia. Late Quaternary stadial-interstadial climate variability in arctic West Beringia is preserved at millennial resolution in the Ice Complex. A MIS3 climate optimum was revealed between 48 and 38 ka BP from the Ice Complex on Bol'shoy Lyakhovsky Island.

  4. Regional variability in sea ice melt in a changing Arctic

    OpenAIRE

    Perovich, Donald K.; Richter-Menge, Jacqueline A.

    2015-01-01

    In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of...

  5. On the existence of stable seasonally varying Arctic sea ice

    CERN Document Server

    Moon, W

    2012-01-01

    Within the framework lower order thermodynamic theories for the climatic evolution of Arctic sea ice we isolate the conditions required for the existence of stable seasonally-varying ice states. This is done by constructing a two-season model from the continuously evolving theory of Eisenman and Wettlaufer (2009) and showing that the necessary and sufficient condition for stable seasonally-varying states resides in the relaxation of the constant annual average short-wave radiative forcing. This forcing is examined within the scenario of greenhouse gas warming, as a function of which stability conditions are discerned.

  6. Importance of Chemical Composition of Ice Nuclei on the Formation of Arctic Ice Clouds

    Science.gov (United States)

    Keita, Setigui Aboubacar; Girard, Eric

    2016-09-01

    Ice clouds play an important role in the Arctic weather and climate system but interactions between aerosols, clouds and radiation remain poorly understood. Consequently, it is essential to fully understand their properties and especially their formation process. Extensive measurements from ground-based sites and satellite remote sensing reveal the existence of two Types of Ice Clouds (TICs) in the Arctic during the polar night and early spring. TICs-1 are composed by non-precipitating small (radar-unseen) ice crystals of less than 30 μm in diameter. The second type, TICs-2, are detected by radar and are characterized by a low concentration of large precipitating ice crystals ice crystals (>30 μm). To explain these differences, we hypothesized that TIC-2 formation is linked to the acidification of aerosols, which inhibits the ice nucleating properties of ice nuclei (IN). As a result, the IN concentration is reduced in these regions, resulting to a lower concentration of larger ice crystals. Water vapor available for deposition being the same, these crystals reach a larger size. Current weather and climate models cannot simulate these different types of ice clouds. This problem is partly due to the parameterizations implemented for ice nucleation. Over the past 10 years, several parameterizations of homogeneous and heterogeneous ice nucleation on IN of different chemical compositions have been developed. These parameterizations are based on two approaches: stochastic (that is nucleation is a probabilistic process, which is time dependent) and singular (that is nucleation occurs at fixed conditions of temperature and humidity and time-independent). The best approach remains unclear. This research aims to better understand the formation process of Arctic TICs using recently developed ice nucleation parameterizations. For this purpose, we have implemented these ice nucleation parameterizations into the Limited Area version of the Global Multiscale Environmental Model

  7. Data-Driven Modeling and Prediction of Arctic Sea Ice

    Science.gov (United States)

    Kondrashov, Dmitri; Chekroun, Mickael; Ghil, Michael

    2016-04-01

    We present results of data-driven predictive analyses of sea ice over the main Arctic regions. Our approach relies on the Multilayer Stochastic Modeling (MSM) framework of Kondrashov, Chekroun and Ghil [Physica D, 2015] and it leads to probabilistic prognostic models of sea ice concentration (SIC) anomalies on seasonal time scales. This approach is applied to monthly time series of state-of-the-art data-adaptive decompositions of SIC and selected climate variables over the Arctic. We evaluate the predictive skill of MSM models by performing retrospective forecasts with "no-look ahead" for up to 6-months ahead. It will be shown in particular that the memory effects included intrinsically in the formulation of our non-Markovian MSM models allow for improvements of the prediction skill of large-amplitude SIC anomalies in certain Arctic regions on the one hand, and of September Sea Ice Extent, on the other. Further improvements allowed by the MSM framework will adopt a nonlinear formulation and explore next-generation data-adaptive decompositions, namely modification of Principal Oscillation Patterns (POPs) and rotated Multichannel Singular Spectrum Analysis (M-SSA).

  8. Community-based sea ice thickness observatories in the Arctic

    Science.gov (United States)

    Gearheard, S.; Mahoney, A. R.; Huntington, H.; Oshima, T.; Qillaq, T.; Barry, R. G.

    2007-12-01

    The thickness of sea ice is a fundamental diagnostic variable for assessing the state of the ice cover. At the scale of the Arctic Basin, the ice thickness distribution determines the volume of the ice pack and its susceptibility to a warming climate as well as affecting the exchange of heat between the ocean and atmosphere. At the local scale, it dictates where and when it is safe to travel on the ice or through the water. Measuring the thickness of sea ice is challenging both technically and logistically and any measurement program strikes a balance between cost and coverage accordingly. Accurately measuring the thickness of large areas of sea ice generally requires airplanes, ice breakers or submarines and electromagnetic or acoustic devices. In this study, we use one of the least technical methods combined with support from remote communities to establish a set of sea ice observation stations in Barrow (Alaska), Clyde River (Baffin Island, Nunavut) and Qaanaaq (northwest Greenland). We employ hunters from these communities, who are experts in traveling and working on the ice, and train them to deploy ice observation stations and take measurements. Each station consists of snow stakes and hot-wire ice thickness gauges and the local observers take measurements on a weekly basis. Involvement of the community is fundamental to the success of these measurement programs and ensures the data collected are relevant to the local use of the sea ice. Community elders and hunters chose the station locations according to where they hunt and travel and to be representative of local variability. As partners in research, the scientists and local hunters are able to share and synthesize their knowledge; the scientific community gains a better understanding of the extraordinary depth of traditional knowledge and the communities improve their understanding of global changes and ability to adapt. Here we present data from observation stations near Clyde River and Qaanaaq. At Clyde

  9. Characterisation of three regimes of collapsing Arctic ice complex deposits on the SE Laptev Sea coast using biomarkers and dual carbon isotopes

    NARCIS (Netherlands)

    Sanchez-Garcia, Laura; Vonk, Jorien; Charkin, Alexander; Kosmach, Denis; Dudarev, Oleg; Semiletov, Igor; Gustafsson, Örjan

    2014-01-01

    Arctic amplification of climate warming is intensifying the thaw and coastal erosion of the widespread and carbon-rich Siberian Ice Complex Deposits (ICD). Despite the potential for altering long-term carbon dynamics in the Arctic, the susceptibility of organic carbon (OC) to degradation as the ICD

  10. Ocean-ice interactions with possible implications for Arctic ice shelves

    Science.gov (United States)

    Alley, R. B.

    2015-12-01

    Confined ice shelves restrain flow of non-floating ice, allowing ice sheets to grow larger than they otherwise would. Ice shelves lead a precarious existence, subject to fragmentation if sufficient meltwater fills crevasses, and very sensitive to even slight warming of water beneath. Ice shelves tend to exist in the coldest waters in the world ocean, often overlying warmer, more-saline waters. Changes in water temperature or circulation generally shrink existing ice shelves and raise sea level by unbuttressing the non-floating ice, and this is likely the most important control on marine-ending parts of land ice, exceeding the influence of sea-level or accumulation-rate changes. Advance of an ice-shelf grounding line into warmer, deeper water will increase melting rates, reduce buttressing, and tend to stabilize the grounding line near or above the upper limit of that warmer water. This physical understanding indicates that the oceanographic state, and its interaction with tributary ice streams, must have been central in the extent of Arctic ice shelves once sufficient cooling occurred to allow extensive advance of land ice into the ocean.

  11. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    Science.gov (United States)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  12. Buried glacier ice in permafrost, a window to the past: examples from Bylot Island, Canadian Arctic

    Science.gov (United States)

    Fortier, D.; Coulombe, S.; Kanevskiy, M. Z.; Paquette, M.; Shur, Y.; Stephani, E.

    2011-12-01

    related to glacio-hydrologic supercooling, that we observed at the Matanuska Glacier in Alaska. Interestingly, the various types of ice contained in buried glacier ice permafrost date back to the englacial ice formation and its subsequent deformation by glacier flow and glacio-hydrological dynamics. It is thus older by several centuries to millennia than the permafrost aggradation itself (burial and active layer development) and we used the term antegenetic, in opposition to epigenetic or syngenetic, to characterize this type of permafrost. Buried glacier ice is a window to the past and a unique tool to reconstruct the paleogeography and paleoclimatology of Arctic regions. In a warming climate, as glaciers are receding, the burial of ice in the proglacial environment will offer opportunities to characterize antegenetic permafrost aggradation and its related cryofacies. In warming permafrost environments, as active layers on slope deepen and detachment slides are triggered, more buried Pleistocene glacier ice will likely be exposed.

  13. A Microwave Technique for Mapping Ice Temperature in the Arctic Seasonal Sea Ice Zone

    Science.gov (United States)

    St.Germain, Karen M.; Cavalieri, Donald J.

    1997-01-01

    A technique for deriving ice temperature in the Arctic seasonal sea ice zone from passive microwave radiances has been developed. The algorithm operates on brightness temperatures derived from the Special Sensor Microwave/Imager (SSM/I) and uses ice concentration and type from a previously developed thin ice algorithm to estimate the surface emissivity. Comparisons of the microwave derived temperatures with estimates derived from infrared imagery of the Bering Strait yield a correlation coefficient of 0.93 and an RMS difference of 2.1 K when coastal and cloud contaminated pixels are removed. SSM/I temperatures were also compared with a time series of air temperature observations from Gambell on St. Lawrence Island and from Point Barrow, AK weather stations. These comparisons indicate that the relationship between the air temperature and the ice temperature depends on ice type.

  14. Arctic sea-ice cover and sea-ice cover anomalies over eastern Canadian waters

    Energy Technology Data Exchange (ETDEWEB)

    Agnew, T.

    1990-01-01

    Concerns about global climate warming have increased interest in climate monitoring and analysis of climate trends in Canada. Sea-ice cover is of interest for climate monitoring since it is very sensitive to changes in the climate controls over a region and is an integrator of temperature anomalies over periods of a week and longer. In addition, climate models suggest that polar regions will have the largest climate warming signal. The existence of long-term digital sea-ice databases makes analysis of sea ice as a climate change indicator possible. The northern hemisphere sea-ice concentration database for 1953 to 1988 was qualitatively evaluated for its representativeness over eastern Canadian Arctic waters. Despite inhomogeneity problems, the database identifies the average freezeup and breakup patterns in the Canadian Arctic islands, Baffin Bay/Davis Strait, and the Hudson Bay area, and can be used for sea-ice variability and anomaly studies. However, inhomogeneity problems put into question the use of the database for sea-ice trend analysis. Sea-ice anomalies for the 1982/83 El Nino winter are compared to atmospheric temperature and circulation anomalies over the Baffin Bay/Davis Strait area. Sea-ice anomaly charts for 1953-1988 are calculated and have been made available as an unpublished catalogue within the Canadian Climate Centre. 15 refs., 27 figs.

  15. Rapid Collapse of the Vavilov Ice Cap, Russian High Arctic.

    Science.gov (United States)

    Willis, M. J.; Zheng, W.; Durkin, W. J., IV; Pritchard, M. E.; Ramage, J. M.; Dowdeswell, J. A.; Benham, T. J.; Glazovsky, A.; Macheret, Y.; Porter, C. C.

    2016-12-01

    Cold based ice caps and glaciers are thought to respond slowly to environmental changes. As sea ice cover evolves in the Arctic, a feedback process alters air-temperatures and precipitation patterns across the region. During the last decades of the 20th century the land-terminating western margin of the Vavilov Ice Cap, on October Revolution Island of the Severnaya Zemlya Archipelago, advanced slowly westwards. The advance was driven by precipitation changes that occurred about half a millennia ago. InSAR shows that in 1996 the margin sustained ice speeds of around 20 m/yr. By 2000 the ice front had moved a short distance into the Kara Sea and had transitioned to a marine-terminating front, although an ice apron around the ice margin indicates the ice there was still frozen to the bed and there is no evidence of calving in satellite imagery. In 2013 ice motions near the terminus had accelerated to around 1 m/day. By late 2015 the main trunk of the newly activated outlet glacier attained speeds of 25 m/day and the inland portion of the ice cap thinned at rates of more than 0.3 m/day. The acceleration of the outlet glacier occurred due to its advance over weak, water-saturated marine sediments that provide little resistance to ice flow, and to the removal of lateral resistive stresses as the glacier advanced out into an open embayment. Longitudinal stretching at the front forces an increase in the surface slope upstream. Rapid rates of motion inland generate frictional melt at the bed, possibly aided by cryohydrological warming. Large areas of the interior of the Vavilov ice cap are now below the equilibrium line and the grounded portion of the ice cap is losing mass at a rate of 4.5 km3 w.e./year. The changes at the Vavilov are likely irrecoverable in a warming climate due to a reduction in the accumulation area of the ice cap. Increased precipitation drove the advance, which accelerated due to the presence of soft sediments. The acceleration lowered the elevation

  16. A Large Eddy Simulation Study of Heat Entrainment under Sea Ice in the Canadian Arctic Basin

    Science.gov (United States)

    Ramudu, E.; Yang, D.; Gelderloos, R.; Meneveau, C. V.; Gnanadesikan, A.

    2016-12-01

    Sea ice cover in the Arctic has declined rapidly in recent decades. The much faster than projected retreat suggests that climate models may be missing some key processes, or that these processes are not accurately represented. The entrainment of heat from the mixed layer by small-scale turbulence is one such process. In the Canadian Basin of the Arctic Ocean, relatively warm Pacific Summer Water (PSW) resides at the base of the mixed layer. With an increasing influx of PSW, the upper ocean in the Canadian Basin has been getting warmer and fresher since the early 2000s. While studies show a correlation between sea ice reduction and an increase in PSW temperature, others argue that PSW intrusions in the Canadian Basin cannot affect sea ice thickness because the strongly-stratified halocline prevents heat from the PSW layer from being entrained into the mixed layer and up to the basal ice surface. In this study, we try to resolve this conundrum by simulating the turbulent entrainment of heat from the PSW layer to a moving basal ice surface using large eddy simulation (LES). The LES model is based on a high-fidelity spectral approach on horizontal planes, and includes a Lagrangian dynamic subgrid model that reduces the need for empirical inputs for subgrid-scale viscosities and diffusivities. This LES tool allows us to investigate physical processes in the mixed layer at a very fine scale. We focus our study on summer conditions, when ice is melting, and show for a range of ice-drift velocities, halocline temperatures, and halocline salinity gradients characteristic of the Canadian Basin how much heat can be entrained from the PSW layer to the sea ice. Our results can be used to improve parameterizations of vertical heat flux under sea ice in coarse-grid ocean and climate models.

  17. Real-time Data Assimilation of Satellite Derived Ice Concentration into the Arctic Cap Nowcast/Forecast System (ACNFS)

    Science.gov (United States)

    2011-09-01

    North America , Technology Solutions Group Stennis Space Center, MS 39529 USA M.W. Phelps Jacobs Engineering Stennis Space Center, MS 39529 USA...precipitation rates (i.e., snowfall ); a model of ice dynamics that predicts the velocity field of the ice pack based on a model of the material strength of the...the Data Assimilation and Model Evaluation Experiments North Atlantic data, the International Bathymetric Chart of the Arctic Ocean data, the

  18. Circumpolar thinning of Arctic sea ice following the 2007 record ice extent minimum

    OpenAIRE

    Giles, K.A.; Laxon, S. W.; Ridout, A. L.

    2008-01-01

    September 2007 marked a record minimum in sea ice extent. While there have been many studies published recently describing the minimum and its causes, little is known about how the ice thickness has changed in the run up to, and following, the summer of 2007. Using satellite radar altimetry data, covering the Arctic Ocean up to 81.5 degrees North, we show that the average winter sea ice thickness anomaly, after the melt season of 2007, was 0.26 m below the 2002/2003 to 2007/2008 average. More...

  19. Pan-Arctic simulation of coupled nutrient-sulfur cycling due to sea ice biology : Preliminary results

    NARCIS (Netherlands)

    Elliott, S.; Deal, C.; Humphries, G.; Hunke, E.; Jeffery, N.; Jin, M.; Levasseur, M.; Stefels, J.

    2012-01-01

    A dynamic model is constructed for interactive silicon, nitrogen, sulfur processing in and below Arctic sea ice, by ecosystems residing in the lower few centimeters of the distributed pack. A biogeochemically active bottom layer supporting sources/sinks for the pennate diatoms is appended to thickne

  20. The central role of diminishing sea ice in recent Arctic temperature amplification.

    Science.gov (United States)

    Screen, James A; Simmonds, Ian

    2010-04-29

    The rise in Arctic near-surface air temperatures has been almost twice as large as the global average in recent decades-a feature known as 'Arctic amplification'. Increased concentrations of atmospheric greenhouse gases have driven Arctic and global average warming; however, the underlying causes of Arctic amplification remain uncertain. The roles of reductions in snow and sea ice cover and changes in atmospheric and oceanic circulation, cloud cover and water vapour are still matters of debate. A better understanding of the processes responsible for the recent amplified warming is essential for assessing the likelihood, and impacts, of future rapid Arctic warming and sea ice loss. Here we show that the Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover. Changes in cloud cover, in contrast, have not contributed strongly to recent warming. Increases in atmospheric water vapour content, partly in response to reduced sea ice cover, may have enhanced warming in the lower part of the atmosphere during summer and early autumn. We conclude that diminishing sea ice has had a leading role in recent Arctic temperature amplification. The findings reinforce suggestions that strong positive ice-temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss, and will probably affect polar ecosystems, ice-sheet mass balance and human activities in the Arctic.

  1. Collaborative Project. Understanding the effects of tides and eddies on the ocean dynamics, sea ice cover and decadal/centennial climate prediction using the Regional Arctic Climate Model (RACM)

    Energy Technology Data Exchange (ETDEWEB)

    Hutchings, Jennifer [Univ. of Alaska, Fairbanks, AK (United States); Joseph, Renu [Univ. of Alaska, Fairbanks, AK (United States)

    2013-09-14

    The goal of this project is to develop an eddy resolving ocean model (POP) with tides coupled to a sea ice model (CICE) within the Regional Arctic System Model (RASM) to investigate the importance of ocean tides and mesoscale eddies in arctic climate simulations and quantify biases associated with these processes and how their relative contribution may improve decadal to centennial arctic climate predictions. Ocean, sea ice and coupled arctic climate response to these small scale processes will be evaluated with regard to their influence on mass, momentum and property exchange between oceans, shelf-basin, ice-ocean, and ocean-atmosphere. The project will facilitate the future routine inclusion of polar tides and eddies in Earth System Models when computing power allows. As such, the proposed research addresses the science in support of the BER’s Climate and Environmental Sciences Division Long Term Measure as it will improve the ocean and sea ice model components as well as the fully coupled RASM and Community Earth System Model (CESM) and it will make them more accurate and computationally efficient.

  2. 30-Year Satellite Record Reveals Accelerated Arctic Sea Ice Loss, Antarctic Sea Ice Trend Reversal

    Science.gov (United States)

    Cavalieri, Donald J.; Parkinson, C. L.; Vinnikov, K. Y.

    2003-01-01

    Arctic sea ice extent decreased by 0.30 plus or minus 0.03 x 10(exp 6) square kilometers per decade from 1972 through 2002, but decreased by 0.36 plus or minus 0.05 x 10(exp 6) square kilometers per decade from 1979 through 2002, indicating an acceleration of 20% in the rate of decrease. In contrast to the Arctic, the Antarctic sea ice extent decreased dramatically over the period 1973-1977, then gradually increased, with an overall 30-year trend of -0.15 plus or minus 0.08 x 10(exp 6) square kilometers per 10yr. The trend reversal is attributed to a large positive anomaly in Antarctic sea ice extent observed in the early 1970's.

  3. Ecosystems on ice: the microbial ecology of Markham Ice Shelf in the high Arctic.

    Science.gov (United States)

    Vincent, Warwick F; Mueller, Derek R; Bonilla, Sylvia

    2004-04-01

    Microbial communities occur throughout the cryosphere in a diverse range of ice-dominated habitats including snow, sea ice, glaciers, permafrost, and ice clouds. In each of these environments, organisms must be capable of surviving freeze-thaw cycles, persistent low temperatures for growth, extremes of solar radiation, and prolonged dormancy. These constraints may have been especially important during global cooling events in the past, including the Precambrian glaciations. One analogue of these early Earth conditions is the thick, landfast sea ice that occurs today at certain locations in the Arctic and Antarctic. These ice shelves contain liquid water for a brief period each summer, and support luxuriant microbial mat communities. Our recent studies of these mats on the Markham Ice Shelf (Canadian high Arctic) by high performance liquid chromatography (HPLC) showed that they contain high concentrations of chlorophylls a and b, and several carotenoids notably lutein, echinenone and beta-carotene. The largest peaks in the HPLC chromatograms were two UV-screening compounds known to be produced by cyanobacteria, scytonemin, and its decomposition product scytonemin-red. Microscopic analyses of the mats showed that they were dominated by the chlorophyte genera cf. Chlorosarcinopsis, Pleurastrum, Palmellopsis, and Bracteococcus, and cyanobacteria of the genera Nostoc, Phormidium, Leptolyngbya, and Gloeocapsa. From point transects and localized sampling we estimated a total standing stock on this ice shelf of up to 11,200 tonnes of organic matter. These observations underscore the ability of microbial communities to flourish despite the severe constraints imposed by the cryo-ecosystem environment.

  4. When the Ice Melts: Developing Proactive American Strategy for the Eurasian Arctic

    Science.gov (United States)

    2015-12-01

    953-2269 E-mail: acsc.der.researchorgmailbox@us.af.mil AIR UNIVERSITY AIR COMMAND AND STAFF COLLEGE When the Ice Melts Developing Proactive American...increase as the Arctic ice cap continues to melt . Accessibility hinges on many factors. Foremost among them may be the occurrence of an ice -free...record saying the Arctic’s summer sea ice will fully melt around 2030,” the Arctic Institute report stated.12 However, multiple models show the

  5. Causes for different spatial distributions of minimum Arctic sea-ice extent in 2007 and 2012

    Institute of Scientific and Technical Information of China (English)

    CUI Hongyan; QIAO Fangli; SHU Qi; SONG Yajuan; JIANG Chunfei

    2015-01-01

    Satellite records show the minimum Arctic sea ice extents (SIEs) were observed in the Septembers of 2007 and 2012, but the spatial distributions of sea ice concentration reduction in these two years were quite different. Atmospheric circulation pattern and the upper-ocean state in summer were investigated to explain the difference. By employing the ice-temperature and ice-specific humidity (SH) positive feedbacks in the Arctic Ocean, this paper shows that in 2007 and 2012 the higher surface air temperature (SAT) and sea level pressure (SLP) accompanied by more surface SH and higher sea surface temperature (SST), as a consequence, the strengthened poleward wind was favorable for melting summer Arctic sea ice in different regions in these two years. SAT was the dominant factor influencing the distribution of Arctic sea ice melting. The correlation coefficient is–0.84 between SAT anomalies in summer and the Arctic SIE anomalies in autumn. The increase SAT in different regions in the summers of 2007 and 2012 corresponded to a quicker melting of sea ice in the Arctic. The SLP and related wind were promoting factors connected with SAT. Strengthening poleward winds brought warm moist air to the Arctic and accelerated the melting of sea ice in different regions in the summers of 2007 and 2012. Associated with the rising air temperature, the higher surface SH and SST also played a positive role in reducing summer Arctic sea ice in different regions in these two years, which form two positive feedbacks mechanism.

  6. CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

    Science.gov (United States)

    Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

    2010-01-01

    The past few years have seen the emergence of satellite altimetry as valuable tool for taking quantitative sea ice monitoring beyond the traditional surface extent measurements and into estimates of sea ice thickness and volume, parameters that arc fundamental to improved understanding of polar dynamics and climate modeling. Several studies have now demonstrated the use of both microwave (ERS, Envisat/RA-2) and laser (ICESat/GLAS) satellite altimeters for determining sea ice thickness. The complexity of polar environments, however, continues to make sea ice thickness determination a complicated remote sensing task and validation studies remain essential for successful monitoring of sea ice hy satellites. One such validation effort, the Arctic Aircraft Altimeter (AAA) campaign of2006. included underflights of Envisat and ICESat north of the Canadian Archipelago using NASA's P-3 aircraft. This campaign compared Envisat and ICESat sea ice elevation measurements with high-resolution airborne elevation measurements, revealing the impact of refrozen leads on radar altimetry and ice drift on laser altimetry. Continuing this research and validation effort, the Canada Basin Sea Ice Thickness (CBSIT) experiment was completed in April 2009. CBSIT was conducted by NOAA. and NASA as part of NASA's Operation Ice Bridge, a gap-filling mission intended to supplement sea and land ice monitoring until the launch of NASA's ICESat-2 mission. CBIST was flown on the NASA P-3, which was equipped with a scanning laser altimeter, a Ku-band snow radar, and un updated nadir looking photo-imaging system. The CB5IT campaign consisted of two flights: an under flight of Envisat along a 1000 km track similar to that flown in 2006, and a flight through the Nares Strait up to the Lincoln Sea that included an overflight of the Danish GreenArc Ice Camp off the coast of northern Greenland. We present an examination of data collected during this campaign, comparing airborne laser altimeter measurements

  7. Sea ice inertial oscillations in the Arctic Basin

    Directory of Open Access Journals (Sweden)

    F. Gimbert

    2012-10-01

    Full Text Available An original method to quantify the amplitude of inertial motion of oceanic and ice drifters, through the introduction of a non-dimensional parameter M defined from a spectral analysis, is presented. A strong seasonal dependence of the magnitude of sea ice inertial oscillations is revealed, in agreement with the corresponding annual cycles of sea ice extent, concentration, thickness, advection velocity, and deformation rates. The spatial pattern of the magnitude of the sea ice inertial oscillations over the Arctic Basin is also in agreement with the sea ice thickness and concentration patterns. This argues for a strong interaction between the magnitude of inertial motion on one hand, the dissipation of energy through mechanical processes, and the cohesiveness of the cover on the other hand. Finally, a significant multi-annual evolution towards greater magnitudes of inertial oscillations in recent years, in both summer and winter, is reported, thus concomitant with reduced sea ice thickness, concentration and spatial extent.

  8. Arctic Ocean sea ice drift origin derived from artificial radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Camara-Mor, P., E-mail: patricia.camara@uab.es [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Masque, P. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Garcia-Orellana, J. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Cochran, J.K. [School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Mas, J.L. [Dpto. de Fisica Aplicada, Universidad de Sevilla, 41012, Seville. Spain (Spain); Chamizo, E. [Centro Nacional de Aceleradores (CNA), Avd. Thomas Alva Edison 7, Isla de la Cartuja, E-41092, Seville (Spain); Hanfland, C. [Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven (Germany)

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of {sup 137}Cs and {sup 239,240}Pu activities and the {sup 240}Pu/{sup 239}Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The {sup 240}Pu/{sup 239}Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the {sup 240}Pu/{sup 239}Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the {sup 137}Cs and {sup 239,240}Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  9. The frequency and extent of sub-ice phytoplankton blooms in the Arctic Ocean

    Science.gov (United States)

    Horvat, Christopher; Jones, David Rees; Iams, Sarah; Schroeder, David; Flocco, Daniela; Feltham, Daniel

    2017-01-01

    In July 2011, the observation of a massive phytoplankton bloom underneath a sea ice–covered region of the Chukchi Sea shifted the scientific consensus that regions of the Arctic Ocean covered by sea ice were inhospitable to photosynthetic life. Although the impact of widespread phytoplankton blooms under sea ice on Arctic Ocean ecology and carbon fixation is potentially marked, the prevalence of these events in the modern Arctic and in the recent past is, to date, unknown. We investigate the timing, frequency, and evolution of these events over the past 30 years. Although sea ice strongly attenuates solar radiation, it has thinned significantly over the past 30 years. The thinner summertime Arctic sea ice is increasingly covered in melt ponds, which permit more light penetration than bare or snow-covered ice. Our model results indicate that the recent thinning of Arctic sea ice is the main cause of a marked increase in the prevalence of light conditions conducive to sub-ice blooms. We find that as little as 20 years ago, the conditions required for sub-ice blooms may have been uncommon, but their frequency has increased to the point that nearly 30% of the ice-covered Arctic Ocean in July permits sub-ice blooms. Recent climate change may have markedly altered the ecology of the Arctic Ocean. PMID:28435859

  10. Eastern-Western Arctic Sea Ice Analysis.

    Science.gov (United States)

    1979-01-01

    3 .. 2 -~e, 8 6 8.’ PZ - 68, II 4-6 7-8O"W .2 010 -A 1-11 4-ŕ 󈧕 7 .1 1 -- ’ 5-7,* o / AA SO TH R IC L,’l % Dae- -. A /ST 1 L NAY5WA JON IC CETE ... CETE -INI /NN ICE IC CENER IGO ENTR METLN -T 175E/ IS /WIO 6W NW 15W1 4W10 n 5E70E15 0 50E 40E 30E 20E1 0IE 0 low 20W low 40# 0W 80E 85E 920E 925E 130ULM

  11. Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission

    Science.gov (United States)

    Notz, Dirk; Stroeve, Julienne

    2016-11-01

    Arctic sea ice is retreating rapidly, raising prospects of a future ice-free Arctic Ocean during summer. Because climate-model simulations of the sea-ice loss differ substantially, we used a robust linear relationship between monthly-mean September sea-ice area and cumulative carbon dioxide (CO2) emissions to infer the future evolution of Arctic summer sea ice directly from the observational record. The observed linear relationship implies a sustained loss of 3 ± 0.3 square meters of September sea-ice area per metric ton of CO2 emission. On the basis of this sensitivity, Arctic sea ice will be lost throughout September for an additional 1000 gigatons of CO2 emissions. Most models show a lower sensitivity, which is possibly linked to an underestimation of the modeled increase in incoming longwave radiation and of the modeled transient climate response.

  12. Propaganda, News, or Education: Reporting Changing Arctic Sea Ice Conditions

    Science.gov (United States)

    Leitzell, K.; Meier, W.

    2010-12-01

    The National Snow and Ice Data Center provides information on Arctic sea ice conditions via the Arctic Sea Ice News & Analysis (ASINA) website. As a result of this effort to explain climatic data to the general public, we have attracted a huge amount of attention from our readers. Sometimes, people write to thank us for the information and the explanation. But people also write to accuse us of bias, slant, or outright lies in our posts. The topic of climate change is a minefield full of political animosity, and even the most carefully written verbiage can appear incomplete or biased to some audiences. Our strategy has been to report the data and stick to the areas in which our scientists are experts. The ASINA team carefully edits our posts to make sure that all statements are based on the science and not on opinion. Often this means using some technical language that may be difficult for a layperson to understand. However, we provide concise definitions for technical terms where appropriate. The hope is that by communicating the data clearly, without an agenda, we can let the science speak for itself. Is this an effective strategy to communicate clearly about the changing climate? Or does it downplay the seriousness of climate change? By writing at a more advanced level and avoiding oversimplification, we require our readers to work harder. But we may also maintain the attention of skeptics, convincing them to read further and become more knowledgeable about the topic.

  13. Arctic sea ice distribution in summer based on aerial photos

    Institute of Scientific and Technical Information of China (English)

    LU Peng; LI Zhijun; ZHANG Zhanhai; DONG Xilu

    2005-01-01

    On the basis of aerial photos of sea ice in the Second Chinese National Arctic Research Expdition during July and September 2003 in the area of74.11°~79.56°N and 144.17°~169.95°W, image processing techniques are used to acquire some geometric parameters of floes, such as fractal dimension, roundness and mean caliper diameter. Latitudinal variation of morphology of arctic ice floes is then obtained, after comparing fractal dimension and roundness which represent geometry of floe edge, the latter is found to show a more obvious tendency with latitude but still not enough to describe floe abrasion. Then mean caliper diameter of ice floe is used as charac-teristic size to analyze floe size distribution, the result reveals that cumulative probabilities of floe sizes agree well with a power-law function, and distribution dimension is generally in the range of 1.05~1.25 and slightly increases as the latitude increases. However slight curvatures are still observed in the plots of cumulative probabilities as in former researches, which can be attributed to both the limitation of sampling area and effect of thermodynamic process.

  14. Distribution and migrations of cetaceans in the Russian Arctic according to observations from aerial ice reconnaissance

    Directory of Open Access Journals (Sweden)

    Stanislav E Belikov

    2002-07-01

    Full Text Available This paper is based on 748 observations of belugas (Delphinapterus leucas and 382 observations of baleen whales in the Russian Arctic, the majority of the data provided by aerial reconnaissance of sea ice (ARSI. Although the data are not suitable for the estimation of the number and density of the animals, they represent a multi-year (1958-1995 range of observations to update our knowledge on the seasonal distribution and migrations of the species. Belugas inhabit not only shelf waters but also the zone of the shelf slope and the abyssal zone of the Arctic Ocean, where the animals appear mostly in summer. In winter belugas were observed only in the Barents Sea. In June-August, the frequency of beluga observations was highest in the Laptev Sea, which has previously been believed to have considerably lower numbers of beluga than the Kara and Barents seas. Patterns of seasonal distribution and ice cover suggest the existence of a natural border preventing or reducing population exchange between belugas inhabiting the western and eastern parts of the Russian Arctic. A brief review of available data on distribution of the narwhal (Monodon monoceros in the Russian Arctic is also given. Two species of baleen whales were frequently seen in the Russian Arctic: the bowhead whale (Balaena mysticetus, and the grey whale (Eschrichtius robustus. The majority of such observations were made in the southeastern part of the East-Siberian Sea and the southern part of the Chukchi Sea. In the Bering Sea baleen whales were usually seen near the Chukotka Peninsula, in Anadyr Bay and southeast of it. Whales were usually seen in ice-free water: observations of whales among rarefied ice and near the ice edge were rare. There were considerable annual and seasonal variations in distribution and migrations of baleen whales in the region, probably caused mainly by the dynamics of ice conditions.

  15. Genome sequences of six Pseudoalteromonas strains isolated from Arctic sea ice.

    Science.gov (United States)

    Bian, Fei; Xie, Bin-Bin; Qin, Qi-Long; Shu, Yan-Li; Zhang, Xi-Ying; Yu, Yong; Chen, Bo; Chen, Xiu-Lan; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2012-02-01

    Yu et al. (Polar Biol. 32:1539-1547, 2009) isolated 199 Pseudoalteromonas strains from Arctic sea ice. We sequenced the genomes of six of these strains, which are affiliated to different Pseudoalteromonas species based on 16S rRNA gene sequences, facilitating the study of physiology and adaptation of Arctic sea ice Pseudoalteromonas strains.

  16. Strategies for the Simulation of Sea Ice Organic Chemistry: Arctic Tests and Development

    CERN Document Server

    Elliott, S; Hunke, E; Deal, C; Jin, M; Wang, S; Smith, E Elliott; Oestreicher, S

    2016-01-01

    A mechanism connecting ice algal ecodynamics with the buildup of organic macromolecules in brine channels is tested offline in a reduced model of pack geochemistry. Driver physical quantities are extracted from the global sea ice dynamics code CICE, including snow height, column thickness and internal temperature. The variables are averaged at the regional scale over ten Arctic biogeographic zones and treated as input matrices at four vertical habitat levels. Nutrient-light-salt limited ice algal growth is computed along with the associated grazing plus mortality. Vertical transport is diffusive but responds to pore structure. Simulated bottom layer chlorophyll maxima are reasonable, though delayed by about a month relative to observations. This highlights major uncertainties deriving from snow thickness variability. Upper level biota are generated intermittently through flooding. Macromolecular injections are represented by the compound classes humics, proteins, polysaccharides and lipids. The fresh biopolym...

  17. Evaluation of Arctic Sea Ice Thickness Simulated by AOMIP Models

    Science.gov (United States)

    Johnson, Mark; Proshutinsky, Andrey; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nimolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; de Cuevas, Beverly

    2011-01-01

    We compare results from six AOMIP model simulations with estimates of sea ice thickness obtained from ICESat, moored and submarine-based upward looking sensors, airborne electromagnetic measurements and drill holes. Our goal is to find patterns of model performance to guide model improvement. The satellite data is pan-arctic from 2004-2008, ice-draft data is from moored instruments in Fram Strait, the Greenland Sea and the Beaufort Sea from 1992-2008 and from submarines from 1975-2000. The drill hole data are from the Laptev and East Siberian marginal seas from 1982-1986 and from coastal stations from 1998-2009. While there are important caveats when comparing modeled results with measurements from different platforms and time periods such as these, the models agree well with moored ULS data. In general, the AOMIP models underestimate the thickness of measured ice thicker than about 2 m and overestimate thickness of ice thinner than 2 m. The simulated results are poor over the fast ice and marginal seas of the Siberian shelves. Averaging over all observational data sets, the better correlations and smaller differences from observed thickness are from the ECCO2 and UW models.

  18. On the Arctic Ocean ice thickness response to changes in the external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Stranne, Christian; Bjoerk, Goeran [University of Gothenburg, Department of Earth Sciences, Box 460, Goeteborg (Sweden)

    2012-12-15

    Submarine and satellite observations show that the Arctic Ocean ice cover has undergone a large thickness reduction and a decrease in the areal extent during the last decades. Here the response of the Arctic Ocean ice cover to changes in the poleward atmospheric energy transport, F{sub wall}, is investigated using coupled atmosphere-ice-ocean column models. Two models with highly different complexity are used in order to illustrate the importance of different internal processes and the results highlight the dramatic effects of the negative ice thickness - ice volume export feedback and the positive surface albedo feedback. The steady state ice thickness as a function of F{sub wall} is determined for various model setups and defines what we call ice thickness response curves. When a variable surface albedo and snow precipitation is included, a complex response curve appears with two distinct regimes: a perennial ice cover regime with a fairly linear response and a less responsive seasonal ice cover regime. The two regimes are separated by a steep transition associated with surface albedo feedback. The associated hysteresis is however small, indicating that the Arctic climate system does not have an irreversible tipping point behaviour related to the surface albedo feedback. The results are discussed in the context of the recent reduction of the Arctic sea ice cover. A new mechanism related to regional and temporal variations of the ice divergence within the Arctic Ocean is presented as an explanation for the observed regional variation of the ice thickness reduction. Our results further suggest that the recent reduction in areal ice extent and loss of multiyear ice is related to the albedo dependent transition between seasonal and perennial ice i.e. large areas of the Arctic Ocean that has previously been dominated by multiyear ice might have been pushed below a critical mean ice thickness, corresponding to the above mentioned transition, and into a state dominated

  19. Links between Arctic sea ice and extreme summer precipi- tation in China:an alternative view

    Institute of Scientific and Technical Information of China (English)

    Petteri Uotila; Alexey Karpechko; Timo Vihma

    2014-01-01

    Potential 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 veriifed 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.

  20. Modeled Arctic sea ice evolution through 2300 in CMIP5 extended RCPs

    Directory of Open Access Journals (Sweden)

    P. J. Hezel

    2014-07-01

    Full Text Available Almost all global climate models and Earth system models that participated in the Coupled Model Intercomparison Project 5 (CMIP5 show strong declines in Arctic sea ice extent and volume under the highest forcing scenario of the representative concentration pathways (RCPs through 2100, including a transition from perennial to seasonal ice cover. Extended RCP simulations through 2300 were completed for a~subset of models, and here we examine the time evolution of Arctic sea ice in these simulations. In RCP2.6, the summer Arctic sea ice extent increases compared to its minimum following the peak radiative forcing in 2044 in all nine models. RCP4.5 demonstrates continued summer Arctic sea ice decline after the forcing stabilizes due to continued warming on longer timescales. Based on the analysis of these two scenarios, we suggest that Arctic summer sea ice extent could begin to recover if and when radiative forcing from greenhouse gas concentrations were to decrease. In RCP8.5 the Arctic Ocean reaches annually ice-free conditions in seven of nine models. The ensemble of simulations completed under the extended RCPs provide insight into the global temperature increase at which sea ice disappears in the Arctic and the reversibility of declines in seasonal sea ice extent.

  1. Contribution of sea-ice loss to Arctic amplification is regulated by Pacific Ocean decadal variability

    Science.gov (United States)

    Screen, James A.; Francis, Jennifer A.

    2016-09-01

    The pace of Arctic warming is about double that at lower latitudes--a robust phenomenon known as Arctic amplification. Many diverse climate processes and feedbacks cause Arctic amplification, including positive feedbacks associated with diminished sea ice. However, the precise contribution of sea-ice loss to Arctic amplification remains uncertain. Through analyses of both observations and model simulations, we show that the contribution of sea-ice loss to wintertime Arctic amplification seems to be dependent on the phase of the Pacific Decadal Oscillation (PDO). Our results suggest that, for the same pattern and amount of sea-ice loss, consequent Arctic warming is larger during the negative PDO phase relative to the positive phase, leading to larger reductions in the poleward gradient of tropospheric thickness and to more pronounced reductions in the upper-level westerlies. Given the oscillatory nature of the PDO, this relationship has the potential to increase skill in decadal-scale predictability of the Arctic and sub-Arctic climate. Our results indicate that Arctic warming in response to the ongoing long-term sea-ice decline is greater (reduced) during periods of the negative (positive) PDO phase. We speculate that the observed recent shift to the positive PDO phase, if maintained and all other factors being equal, could act to temporarily reduce the pace of wintertime Arctic warming in the near future.

  2. Is recent Eurasian winter cooling caused by Arctic sea ice loss?

    Science.gov (United States)

    Kim, Hye-Jin; Son, Seok-Woo; Kim, Kwang-Yul; Kug, Jong-Seong; Kim, Baek-Min; Jeong, Jee-Hoon

    2016-04-01

    The observed surface air temperature in the northern mid-latitudes shows a significant cooling trend in recent winters despite greenhouse gas concentrations continuing to rise. Such an unexpected cooling trend since late 1990's is especially strong over the Eurasia. Here, by performing statistical analyses and climate model experiment, we show that the recent Eurasian cooling trend is at least in part caused by Arctic sea ice loss over the Barents and Kara (BK) seas. A significant time-lagged co-variability is observed between autumn sea ice concentrations over BK seas and winter surface air temperature over the Eurasia. More importantly, the timing of a rapid sea ice loss is consistent with the timing of Eurasian cooling. These results indicate that both interannual variability and long-term trend of Eurasian winter surface air temperature are likely influenced by regional sea ice changes over BK seas. This conjecture is confirmed by climate model experiment. A coupled model, GFDL CM2.1, is integrated with a pre-industrial condition except for the Arctic regions where observed sea surface temperature is relaxed. Ensemble simulations successfully reproduce the recent cooling trend over the Eurasia although the timing is bit delayed (i.e., early 2000's instead of late 1990's). However, it is found that this cooling trend is unlikely explained by linear dynamics, and is not associated with changes in atmospheric blocks.

  3. Anomalous Arctic surface wind patterns and their impacts on September sea ice minima and trend

    Directory of Open Access Journals (Sweden)

    Bingyi Wu

    2012-05-01

    Full Text Available We used monthly mean surface wind data from the National Centers for Environmental Prediction/National Centers for Atmospheric Research (NCEP/NCAR reanalysis dataset during the period 1979–2010 to describe the first two patterns of Arctic surface wind variability by means of the complex vector empirical orthogonal function (CVEOF analysis. The first two patterns respectively account for 31 and 16% of its total anomalous kinetic energy. The leading pattern consists of the two subpatterns: the northern Laptev Sea (NLS pattern and the Arctic dipole (AD pattern. The second pattern contains the northern Kara Sea (NKS pattern and the central Arctic (CA pattern. Over the past two decades, the combined dynamical forcing of the first two patterns has contributed to Arctic September sea ice extent (SIE minima and its declining trend. September SIE minima are mainly associated with the negative phase of the AD pattern and the positive phase of the CA pattern during the summer (July to September season, and both phases coherently show an anomalous anticyclone over the Arctic Ocean. Wind patterns affect September SIE through their frequency and intensity. The negative trend in September SIE over the past two decades is associated with increased frequency and enhanced intensity of the CA pattern during the melting season from April to September. Thus, it cannot be simply attributed to the AD anomaly characterised by the second empirical orthogonal function mode of sea level pressure north of 70°N. The CA pattern exhibited interdecadal variability in the late 1990s, and an anomalous cyclone prevailed before 1997 and was then replaced by an anomalous anticyclone over the Arctic Ocean that is consistent with the rapid decline trend in September SIE. This paper provides an alternative way to identify the dominant patterns of climate variability and investigate their associated Arctic sea ice variability from a dynamical perspective. Indeed, this study

  4. Observed sea ice extent in the Russian Arctic, 1933-2006

    Science.gov (United States)

    Mahoney, Andrew R.; Barry, Roger G.; Smolyanitsky, Vasily; Fetterer, Florence

    2008-11-01

    We present a time series of sea ice extent in the Russian Arctic based on observational sea ice charts compiled by the Arctic and Antarctic Research Institute (AARI). These charts are perhaps the oldest operational sea ice data in existence and show that sea ice extent in the Russian Arctic has generally decreased since the beginning of the chart series in 1933. This retreat has not been continuous, however. For the Russian Arctic as a whole in summer, there have been two periods of retreat separated by a partial recovery between the mid-1950s and mid-1980s. The AARI charts, combined with air temperature records, suggest that the retreat in recent decades is pan-Arctic and year-round in some regions, whereas the early twentieth century retreat was only observed in summer in the Russian Arctic. The AARI ice charts indicate that a significant transition occurred in the Russian Arctic in the mid-1980s, when its sea ice cover began to retreat along with that of the rest of the Arctic. Summertime sea ice extents derived from the AARI data set agree with those derived from passive microwave, including the Hadley Centre's global sea ice coverage and sea surface temperature (HadISST) data set. The HadISST results do not indicate the 1980s transition or the partial recovery that took place before it. The AARI charts therefore add significantly to our understanding of the variability of Arctic sea ice over the last 8 decades, and we recommend their inclusion in future historical data sets of Arctic sea ice.

  5. Under-ice distribution of polar cod Boreogadus saida in the central Arctic Ocean and their association with sea-ice habitat properties

    NARCIS (Netherlands)

    David, Carmen; Lange, Benjamin; Krumpen, Thomas; Schaafsma, F.L.; Franeker, van J.A.; Flores, H.

    2016-01-01

    In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean,

  6. Under-ice distribution of polar cod Boreogadus saida in the central Arctic Ocean and their association with sea-ice habitat properties

    NARCIS (Netherlands)

    David, Carmen; Lange, Benjamin; Krumpen, Thomas; Schaafsma, F.L.; Franeker, van J.A.; Flores, H.

    2016-01-01

    In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean, ho

  7. Sea ice loss enhances wave action at the Arctic coast

    Science.gov (United States)

    Overeem, I.; Anderson, R. Scott; Wobus, C.W.; Clow, G.D.; Urban, F.E.; Matell, N.

    2011-01-01

    Erosion rates of permafrost coasts along the Beaufort Sea accelerated over the past 50 years synchronously with Arctic-wide declines in sea ice extent, suggesting a causal relationship between the two. A fetch-limited wave model driven by sea ice position and local wind data from northern Alaska indicates that the exposure of permafrost bluffs to seawater increased by a factor of 2.5 during 1979-2009. The duration of the open water season expanded from ???45 days to ???95 days. Open water expanded more rapidly toward the fall (???0.92 day yr-1), when sea surface temperatures are cooler, than into the mid-summer (???0.71 days yr-1).Time-lapse imagery demonstrates the relatively efficient erosive action of a single storm in August. Sea surface temperatures have already decreased significantly by fall, reducing the potential impact of thermal erosion due to fall season storm waves. Copyright 2011 by the American Geophysical Union.

  8. Methane excess in Arctic surface water-triggered by sea ice formation and melting.

    Science.gov (United States)

    Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

    2015-11-10

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  9. Methane excess in Arctic surface water- triggered by sea ice formation and melting

    Science.gov (United States)

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-11-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  10. In-situ measured primary productivity of ice algae in Arctic sea ice floes using a new incubation method

    Science.gov (United States)

    Song, Ho Jung; Lee, Jae Hyung; Kim, Gawn Woo; Ahn, So Hyun; Joo, Houng-Min; Jeong, Jin Young; Yang, Eun Jin; Kang, Sung-Ho; Lee, Sang Heon

    2016-09-01

    Recent changes in climate and environmental conditions have had great negative effects such as decreasing sea ice thickness and the extent of Arctic sea ice floes that support ice-related organisms. However, limited field observations hinder the understanding of the impacts of the current changes in the previously ice-covered regions on sea ice algae and other ice-related ecosystems. Our main objective in this study was to measure recent primary production of ice algae and their relative contribution to total primary production (ice plus pelagic primary production). In-situ primary productivity experiments with a new incubation system for ice algae were conducted in 3 sea ice cores at 2 different ice camps in the northern Chukchi Sea, 2014, using a 13C and 15N isotope tracer technique. A new incubation system was tested for conducting primary productivity experiments on ice algae that has several advantages over previous incubation methods, enabling stable carbon and nitrogen uptake experiments on ice algae under more natural environmental conditions. The vertical C-shaped distributions of the ice algal chl- a, with elevated concentrations at the top and bottom of the sea ice were observed in all cores, which is unusual for Arctic sea ice. The mean chl- a concentration (0.05 ± 0.03 mg chl- a m-3) and the daily carbon uptake rates (ranging from 0.55 to 2.23 mg C m-2 d-1) for the ice algae were much lower in this study than in previous studies in the Arctic Ocean. This is likely because of the late sampling periods and thus the substantial melting occurring. Ice algae contributed 1.5-5.7% of the total particulate organic carbon (POC) contents of the combined euphotic water columns and sea ice floes. In comparison, ice algae contributed 4.8-8.6% to the total primary production which is greater than previously reported in the Arctic Ocean. If all of the ice-associated productions were included, the contributions of the sea ice floes to the total primary production

  11. Implications of sea-ice biogeochemistry for oceanic production and emissions of dimethyl sulfide in the Arctic

    Directory of Open Access Journals (Sweden)

    H. Hayashida

    2017-06-01

    Full Text Available Sea ice represents an additional oceanic source of the climatically active gas dimethyl sulfide (DMS for the Arctic atmosphere. To what extent this source contributes to the dynamics of summertime Arctic clouds is, however, not known due to scarcity of field measurements. In this study, we developed a coupled sea ice–ocean ecosystem–sulfur cycle model to investigate the potential impact of bottom-ice DMS and its precursor dimethylsulfoniopropionate (DMSP on the oceanic production and emissions of DMS in the Arctic. The results of the 1-D model simulation were compared with field data collected during May and June of 2010 in Resolute Passage. Our results reproduced the accumulation of DMS and DMSP in the bottom ice during the development of an ice algal bloom. The release of these sulfur species took place predominantly during the earlier phase of the melt period, resulting in an increase of DMS and DMSP in the underlying water column prior to the onset of an under-ice phytoplankton bloom. Production and removal rates of processes considered in the model are analyzed to identify the processes dominating the budgets of DMS and DMSP both in the bottom ice and the underlying water column. When openings in the ice were taken into account, the simulated sea–air DMS flux during the melt period was dominated by episodic spikes of up to 8.1 µmol m−2 d−1. Further model simulations were conducted to assess the effects of the incorporation of sea-ice biogeochemistry on DMS production and emissions, as well as the sensitivity of our results to changes of uncertain model parameters of the sea-ice sulfur cycle. The results highlight the importance of taking into account both the sea-ice sulfur cycle and ecosystem in the flux estimates of oceanic DMS near the ice margins and identify key uncertainties in processes and rates that should be better constrained by new observations.

  12. Comparison and Validation of Four Arctic Sea Ice Thickness Products of the EC POLAR ICE Project

    Science.gov (United States)

    Melsheimer, C.; Makynen, M.; Rasmussen, T. S.; Rudjord, Ø.; Simila, M.; Solberg, R.; Walker, N. P.

    2016-08-01

    Sea ice thickness (SIT) is an important parameter for monitoring Arctic change, modelling and predicting weather and climate, and for navigation and offshore operations. However, SIT is still not very well monitored operationally. In the European Commission (EC) FP7 project "POLAR ICE", three novel SIT products based on different satellite data as well as SIT from a state-of-the- art ocean and sea ice model are fed into a common data handling and distribution system for end users. Each SIT product has different scopes and limitations as to, e.g., spatial and temporal resolution, ice thickness range and geographical domain. The aim of this study is to compare the four different SIT products with each other and with SIT in-situ measurements in order to better understand the differences and limitations, and possibly give recommendations on how to best profit from the synergy of the different data.

  13. Ice-age megafauna in Arctic Alaska: extinction, invasion, survival

    Science.gov (United States)

    Mann, Daniel H.; Groves, Pamela; Kunz, Michael L.; Reanier, Richard E.; Gaglioti, Benjamin V.

    2013-01-01

    Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age megafauna was more diverse in species and possibly contained 6× more individual animals than live in the region today. Megafaunal biomass during the last ice age may have been 30× greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly bears comprised the predator/scavenger guild. The youngest mammoth so far discovered lived ca 13,800 years ago, while horses and bison persisted on the North Slope until at least 12,500 years ago during the Younger Dryas cold interval. The first people arrived on the North Slope ca 13,500 years ago. Bone-isotope measurements and foot-loading characteristics suggest megafaunal niches were segregated along a moisture gradient, with the surviving species (muskox and caribou) utilizing the warmer and moister portions of the vegetation mosaic. As the ice age ended, the moisture gradient shifted and eliminated habitats utilized by the dryland, grazing species (bison, horse, mammoth). The proximate cause for this change was regional paludification, the spread of organic soil horizons and peat. End-Pleistocene extinctions in arctic Alaska represent local, not global extinctions since the megafaunal species lost there persisted to later times elsewhere. Hunting seems unlikely as the cause of these extinctions, but it cannot be ruled out as the final blow to megafaunal populations that were already functionally extinct by the time humans arrived in the region.

  14. Arctic Sea Ice Variability and Trends, 1979-2006

    Science.gov (United States)

    Parkinson, Claire L.; Cavalieri, Donald J.

    2008-01-01

    Analysis of Arctic sea ice extents derived from satellite passive-microwave data for the 28 years, 1979-2006 yields an overall negative trend of -45,100 +/- 4,600 km2/yr (-3.7 +/- 0.4%/decade) in the yearly averages, with negative ice-extent trends also occurring for each of the four seasons and each of the 12 months. For the yearly averages the largest decreases occur in the Kara and Barents Seas and the Arctic Ocean, with linear least squares slopes of -10,600 +/- 2,800 km2/yr (-7.4 +/- 2.0%/decade) and -10,100 +/- 2,200 km2/yr (-1.5 +/- 0.3%/decade), respectively, followed by Baffin Bay/Labrador Sea, with a slope of -8,000 +/- 2,000 km2/yr) -9.0 +/- 2.3%/decade), the Greenland Sea, with a slope of -7,000 +/- 1,400 km2/yr (-9.3 +/- 1.9%/decade), and Hudson Bay, with a slope of -4,500 +/- 900 km2/yr (-5.3 +/- 1.1%/decade). These are all statistically significant decreases at a 99% confidence level. The Seas of Okhotsk and Japan also have a statistically significant ice decrease, although at a 95% confidence level, and the three remaining regions, the Bering Sea, Canadian Archipelago, and Gulf of St. Lawrence, have negative slopes that are not statistically significant. The 28-year trends in ice areas for the Northern Hemisphere total are also statistically significant and negative in each season, each month, and for the yearly averages.

  15. Autonomous Ice Mass Balance Observations for Changing Arctic Sea Ice Conditions

    Science.gov (United States)

    Whitlock, J. D.; Planck, C.; Perovich, D. K.; Richter-Menge, J.; Elder, B. C.; Polashenski, C.

    2016-12-01

    Results from observational data and predictive models agree: the state of the Arctic sea ice cover is in transition with a major shift from thick multiyear ice to thinner seasonal ice. The ice mass-balance represents the integration of all surface and ocean heat fluxes, and frequent temporal measurement can aid in attributing the impact of these forcing fluxes on the ice cover. Autonomous Ice Mass Balance buoys (IMB's) have proved to be important measurement tools allowing in situ, long-term data collection at multiple locations. Seasonal IMB's (SIMB's) are free floating versions of the IMB that allow data collection in thin ice and during times of transition. To accomplish this a custom computer was developed to integrate the scientific instruments, power management, and data communications while providing expanded autonomous functionality. This new design also allows for the easy incorporation of other sensors. Additionally, the latest generation of SIMB includes improvements to make it more stable, longer lasting, easier to deploy, and less expensive. Models can provide important insights as to where to deploy the sea ice mass balance buoys and what measurements are the most important. The resulting dataset from the buoys can be used to inform and assess model results.

  16. Regular network model for the sea ice-albedo feedback in the Arctic.

    Science.gov (United States)

    Müller-Stoffels, Marc; Wackerbauer, Renate

    2011-03-01

    The Arctic Ocean and sea ice form a feedback system that plays an important role in the global climate. The complexity of highly parameterized global circulation (climate) models makes it very difficult to assess feedback processes in climate without the concurrent use of simple models where the physics is understood. We introduce a two-dimensional energy-based regular network model to investigate feedback processes in an Arctic ice-ocean layer. The model includes the nonlinear aspect of the ice-water phase transition, a nonlinear diffusive energy transport within a heterogeneous ice-ocean lattice, and spatiotemporal atmospheric and oceanic forcing at the surfaces. First results for a horizontally homogeneous ice-ocean layer show bistability and related hysteresis between perennial ice and perennial open water for varying atmospheric heat influx. Seasonal ice cover exists as a transient phenomenon. We also find that ocean heat fluxes are more efficient than atmospheric heat fluxes to melt Arctic sea ice.

  17. Polar bear and walrus response to the rapid decline in Arctic sea ice

    Science.gov (United States)

    Oakley, K.; Whalen, M.; Douglas, D.; Udevitz, M.; Atwood, T.; Jay, C.

    2012-01-01

    The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus rosmarus divergens) are dependent on sea ice over the continental shelves of the Arctic Ocean's marginal seas. The continental shelves are shallow regions with high biological productivity, supporting abundant marine life within the water column and on the sea floor. Polar bears use sea ice as a platform for hunting ice seals; walruses use sea ice as a resting platform between dives to forage for clams and other bottom-dwelling invertebrates. How have sea ice changes affected polar bears and walruses? How will anticipated changes affect them in the future?

  18. Methane and Root Dynamics in Arctic Soil

    DEFF Research Database (Denmark)

    D'Imperio, Ludovica

    on the global climate. We investigated two aspects of arctic ecosystem dynamics which are not well represented in climatic models: i) soil methane (CH4) oxidation in dry heath tundra and barren soils and ii) root dynamics in wetlands. Field measurements were carried out during the growing season in Disko Island...

  19. Variability and changes of Arctic sea ice draft distribution – submarine sonar measurements revisited

    Directory of Open Access Journals (Sweden)

    J. Haapala

    2011-10-01

    Full Text Available Changes in the mean sea ice thickness and concentration in the Arctic are well known. However, quantitative information about changes in the ice thickness distribution and the composition of the pack ice is lacking. In this paper we determine the ice draft distributions, mean and modal thicknesses, and their regional and seasonal variability in the Arctic for the time period 1975–2000. We compare characteristics of the Arctic pack ice for the years 1975–1987 and 1988–2000. These periods represent different large-scale atmospheric circulation modes and sea ice circulation patterns, most evident in clearly weaker Beaufort Gyre and stronger as well as westward shifted Transpolar Drift during the later period. The comparison of these two periods reveals that the peak of sea ice draft distributions has narrowed and shifted toward thinner ice, with reductions in both mean and modal ice draft. These noticeable changes are attributed to the loss of thick, mostly deformed ice. Springtime, loss of ice volume with draft greater than 5 m exceeds 35 % in all regions except the Nansen Basin, with as much as 45 % or more at the North Pole and in the Eastern Arctic. Autumn volume reduction, mostly of deformed ice, exceeds 40 % in the Canada Basin only, but is above 30 % also in the Beaufort and Chukchi Seas. During the later period, the volume of ice category consisting thin, mostly level first-year ice, is clearly larger than during the former period, especially in the spring. In the Beaufort Sea region, changes in the composition of ice cover have resulted in a shift of modal draft from level multiyear ice draft range to values of level first-year ice. The regional and seasonal variability of sea ice draft has decreased, since the thinning has been most pronounced in regions with the thickest pack ice (the Western Arctic, and during the spring (0.6–0.8 m per decade.

  20. Fluid dynamics of planetary ices

    CERN Document Server

    Greve, Ralf

    2009-01-01

    The role of water ice in the solar system is reviewed from a fluid-dynamical point of view. On Earth and Mars, water ice forms ice sheets, ice caps and glaciers at the surface, which show glacial flow under their own weight. By contrast, water ice is a major constituent of the bulk volume of the icy satellites in the outer solar system, and ice flow can occur as thermal convection. The rheology of polycrystalline aggregates of ordinary, hexagonal ice Ih is described by a power law, different forms of which are discussed. The temperature dependence of the ice viscosity follows an Arrhenius law. Therefore, the flow of ice in a planetary environment constitutes a thermo-mechanically coupled problem; its model equations are obtained by inserting the flow law and the thermodynamic material equations in the balance laws of mass, momentum and energy. As an example of gravity-driven flow, the polar caps of Mars are discussed. For the north-polar cap, large-scale flow velocities of the order of 0.1...1 mm/a are likely...

  1. Dynamic preconditioning of the September sea-ice extent minimum

    Science.gov (United States)

    Williams, James; Tremblay, Bruno; Newton, Robert; Allard, Richard

    2016-04-01

    There has been an increased interest in seasonal forecasting of the sea-ice extent in recent years, in particular the minimum sea-ice extent. We propose a dynamical mechanism, based on winter preconditioning through first year ice formation, that explains a significant fraction of the variance in the anomaly of the September sea-ice extent from the long-term linear trend. To this end, we use a Lagrangian trajectory model to backtrack the September sea-ice edge to any time during the previous winter and quantify the amount of sea-ice divergence along the Eurasian and Alaskan coastlines as well as the Fram Strait sea-ice export. We find that coastal divergence that occurs later in the winter (March, April and May) is highly correlated with the following September sea-ice extent minimum (r = -0.73). This is because the newly formed first year ice will melt earlier allowing for other feedbacks (e.g. ice albedo feedback) to start amplifying the signal early in the melt season when the solar input is large. We find that the winter mean Fram Strait sea-ice export anomaly is also correlated with the minimum sea-ice extent the following summer. Next we backtrack a synthetic ice edge initialized at the beginning of the melt season (June 1st) in order to develop hindcast models of the September sea-ice extent that do not rely on a-priori knowledge of the minimum sea-ice extent. We find that using a multi-variate regression model of the September sea-ice extent anomaly based on coastal divergence and Fram Strait ice export as predictors reduces the error by 41%. A hindcast model based on the mean DJFMA Arctic Oscillation index alone reduces the error by 24%.

  2. Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

    Science.gov (United States)

    Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

    2010-01-01

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

  3. Observed anomalous atmospheric patterns in summers of unusual Arctic sea ice melt

    OpenAIRE

    Knudsen, Erlend M.; Orsolini, Yvan J.; Furevik, Tore; Hodges, Kevin I.

    2015-01-01

    The Arctic sea ice retreat has accelerated over the last decade. The negative trend is largest in summer, but substantial interannual variability still remains. Here we explore observed atmospheric conditions and feedback mechanisms during summer months of anomalous sea ice melt in the Arctic. Compositing months of anomalous low and high sea ice melt over 1979–2013, we find distinct patterns in atmospheric circulation, precipitation, radiation, and temperature. Compared to summer months of\\ud...

  4. Airborne observations of changes of ice sheet and sea ice in the Arctic using CryoVEx campaign data

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Skourup, Henriette; Forsberg, René

    DTU Space have collected surface elevation observations of the Arctic sea ice and land ice since 1998 using laser scanning and radar altimetry from a small fixed‐wing Twin‐Otter aircraft. The observations provide unique datasets for studying ongoing changes, and support the analysis of satellite......‐launch validation studies, with several aircraft and international in‐situ ground teams participating, both in Greenland, Arctic Canada, and Svalbard. The methods and campaigns are outlined together with examples of results.The campaigns focused on five main validation sites: Devon ice cap (Canada), Austfonna ice...

  5. Airborne Surveys of Snow Depth over Arctic Sea Ice

    Science.gov (United States)

    Kwok, R.; Panzer, B.; Leuschen, C.; Pang, S.; Markus, T.; Holt, B.; Gogineni, S.

    2011-01-01

    During the spring of 2009, an ultrawideband microwave radar was deployed as part of Operation IceBridge to provide the first cross-basin surveys of snow thickness over Arctic sea ice. In this paper, we analyze data from three approx 2000 km transects to examine detection issues, the limitations of the current instrument, and the regional variability of the retrieved snow depth. Snow depth is the vertical distance between the air \\snow and snow-ice interfaces detected in the radar echograms. Under ideal conditions, the per echogram uncertainty in snow depth retrieval is approx 4 - 5 cm. The finite range resolution of the radar (approx 5 cm) and the relative amplitude of backscatter from the two interfaces limit the direct retrieval of snow depths much below approx 8 cm. Well-defined interfaces are observed over only relatively smooth surfaces within the radar footprint of approx 6.5 m. Sampling is thus restricted to undeformed, level ice. In early April, mean snow depths are 28.5 +/- 16.6 cm and 41.0 +/- 22.2 cm over first-year and multiyear sea ice (MYI), respectively. Regionally, snow thickness is thinner and quite uniform over the large expanse of seasonal ice in the Beaufort Sea, and gets progressively thicker toward the MYI cover north of Ellesmere Island, Greenland, and the Fram Strait. Snow depth over MYI is comparable to that reported in the climatology by Warren et al. Ongoing improvements to the radar system and the utility of these snow depth measurements are discussed.

  6. Bacterial communities of surface mixed layer in the Pacific sector of the western Arctic Ocean during sea-ice melting.

    Science.gov (United States)

    Han, Dukki; Kang, Ilnam; Ha, Ho Kyung; Kim, Hyun Cheol; Kim, Ok-Sun; Lee, Bang Yong; Cho, Jang-Cheon; Hur, Hor-Gil; Lee, Yoo Kyung

    2014-01-01

    From July to August 2010, the IBRV ARAON journeyed to the Pacific sector of the Arctic Ocean to monitor bacterial variation in Arctic summer surface-waters, and temperature, salinity, fluorescence, and nutrient concentrations were determined during the ice-melting season. Among the measured physicochemical parameters, we observed a strong negative correlation between temperature and salinity, and consequently hypothesized that the melting ice decreased water salinity. The bacterial community compositions of 15 samples, includicng seawater, sea-ice, and melting pond water, were determined using a pyrosequencing approach and were categorized into three habitats: (1) surface seawater, (2) ice core, and (3) melting pond. Analysis of these samples indicated the presence of local bacterial communities; a deduction that was further corroborated by the discovery of seawater- and ice-specific bacterial phylotypes. In all samples, the Alphaproteobacteria, Flavobacteria, and Gammaproteobacteria taxa composed the majority of the bacterial communities. Among these, Alphaproteobacteria was the most abundant and present in all samples, and its variation differed among the habitats studied. Linear regression analysis suggested that changes in salinity could affect the relative proportion of Alphaproteobacteria in the surface water. In addition, the species-sorting model was applied to evaluate the population dynamics and environmental heterogeneity in the bacterial communities of surface mixed layer in the Arctic Ocean during sea-ice melting.

  7. Bacterial communities of surface mixed layer in the Pacific sector of the western Arctic Ocean during sea-ice melting.

    Directory of Open Access Journals (Sweden)

    Dukki Han

    Full Text Available From July to August 2010, the IBRV ARAON journeyed to the Pacific sector of the Arctic Ocean to monitor bacterial variation in Arctic summer surface-waters, and temperature, salinity, fluorescence, and nutrient concentrations were determined during the ice-melting season. Among the measured physicochemical parameters, we observed a strong negative correlation between temperature and salinity, and consequently hypothesized that the melting ice decreased water salinity. The bacterial community compositions of 15 samples, includicng seawater, sea-ice, and melting pond water, were determined using a pyrosequencing approach and were categorized into three habitats: (1 surface seawater, (2 ice core, and (3 melting pond. Analysis of these samples indicated the presence of local bacterial communities; a deduction that was further corroborated by the discovery of seawater- and ice-specific bacterial phylotypes. In all samples, the Alphaproteobacteria, Flavobacteria, and Gammaproteobacteria taxa composed the majority of the bacterial communities. Among these, Alphaproteobacteria was the most abundant and present in all samples, and its variation differed among the habitats studied. Linear regression analysis suggested that changes in salinity could affect the relative proportion of Alphaproteobacteria in the surface water. In addition, the species-sorting model was applied to evaluate the population dynamics and environmental heterogeneity in the bacterial communities of surface mixed layer in the Arctic Ocean during sea-ice melting.

  8. A study on the dynamic tie points ASI algorithm in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    HAO Guanghua; SU Jie

    2015-01-01

    Sea ice concentration is an important parameter for polar sea ice monitoring. Based on 89 GHz AMSR-E (Advanced Microwave Scanning Radiometer for Earth Observing System) data, a gridded high-resolution passive microwave sea ice concentration product can be obtained using the ASI (the Arctic Radiation And Turbulence Interaction Study (ARTIST) Sea Ice) retrieval algorithm. Instead of using fixed-point values, we developed ASI algorithm based on daily changed tie points, called as the dynamic tie point ASI algorithm in this study. Here the tie points are expressed as the brightness temperature polarization difference of open water and 100% sea ice. In 2010, the yearly-averaged tie points of open water and sea ice in Arctic are estimated to be 50.8 K and 7.8 K, respectively. It is confirmed that the sea ice concentrations retrieved by the dynamic tie point ASI algorithm can increase (decrease) the sea ice concentrations in low-value (high-value) areas. This improved the sea ice concentrations by present retrieval algorithm from microwave data to some extent. Comparing with the products using fixed tie points, the sea ice concentrations retrieved from AMSR-E data by using the dynamic tie point ASI algorithm are closer to those obtained from MODIS (Moderate-resolution Imaging Spectroradiometer) data. In 40 selected cloud-free sample regions, 95% of our results have smaller mean differences and 75% of our results have lower root mean square (RMS) differences compare with those by the fixed tie points.

  9. Selected physical, biological and biogeochemical implications of a rapidly changing Arctic Marginal Ice Zone

    Science.gov (United States)

    Barber, David G.; Hop, Haakon; Mundy, Christopher J.; Else, Brent; Dmitrenko, Igor A.; Tremblay, Jean-Eric; Ehn, Jens K.; Assmy, Philipp; Daase, Malin; Candlish, Lauren M.; Rysgaard, Søren

    2015-12-01

    The Marginal Ice Zone (MIZ) of the Arctic Ocean is changing rapidly due to a warming Arctic climate with commensurate reductions in sea ice extent and thickness. This Pan-Arctic review summarizes the main changes in the Arctic ocean-sea ice-atmosphere (OSA) interface, with implications for primary- and secondary producers in the ice and the underlying water column. Changes in the Arctic MIZ were interpreted for the period 1979-2010, based on best-fit regressions for each month. Trends of increasingly open water were statistically significant for each month, with quadratic fit for August-November, illustrating particularly strong seasonal feedbacks in sea-ice formation and decay. Geographic interpretations of physical and biological changes were based on comparison of regions with significant changes in sea ice: (1) The Pacific Sector of the Arctic Ocean including the Canada Basin and the Beaufort, Chukchi and East Siberian seas; (2) The Canadian Arctic Archipelago; (3) Baffin Bay and Hudson Bay; and (4) the Barents and Kara seas. Changes in ice conditions in the Barents sea/Kara sea region appear to be primarily forced by ocean heat fluxes during winter, whereas changes in the other sectors appear to be more summer-autumn related and primarily atmospherically forced. Effects of seasonal and regional changes in OSA-system with regard to increased open water were summarized for photosynthetically available radiation, nutrient delivery to the euphotic zone, primary production of ice algae and phytoplankton, ice-associated fauna and zooplankton, and gas exchange of CO2. Changes in the physical factors varied amongst regions, and showed direct effects on organisms linked to sea ice. Zooplankton species appear to be more flexible and likely able to adapt to variability in the onset of primary production. The major changes identified for the ice-associated ecosystem are with regard to production timing and abundance or biomass of ice flora and fauna, which are related to

  10. The Timing of Arctic Sea Ice Advance and Retreat as an Indicator of Ice-Dependent Marine Mammal Habitat

    Science.gov (United States)

    Stern, H. L.; Laidre, K. L.

    2013-12-01

    The Arctic is widely recognized as the front line of climate change. Arctic air temperature is rising at twice the global average rate, and the sea-ice cover is shrinking and thinning, with total disappearance of summer sea ice projected to occur in a matter of decades. Arctic marine mammals such as polar bears, seals, walruses, belugas, narwhals, and bowhead whales depend on the sea-ice cover as an integral part of their existence. While the downward trend in sea-ice extent in a given month is an often-used metric for quantifying physical changes in the ice cover, it is not the most relevant measure for characterizing changes in the sea-ice habitat of marine mammals. Species that depend on sea ice are behaviorally tied to the annual retreat of sea ice in the spring and advance in the fall. Changes in the timing of the spring retreat and the fall advance are more relevant to Arctic marine species than changes in the areal sea-ice coverage in a particular month of the year. Many ecologically important regions of the Arctic are essentially ice-covered in winter and ice-free in summer, and will probably remain so for a long time into the future. But the dates of sea-ice retreat in spring and advance in fall are key indicators of climate change for ice-dependent marine mammals. We use daily sea-ice concentration data derived from satellite passive microwave sensors to calculate the dates of sea-ice retreat in spring and advance in fall in 12 regions of the Arctic for each year from 1979 through 2013. The regions include the peripheral seas around the Arctic Ocean (Beaufort, Chukchi, East Siberian, Laptev, Kara, Barents), the Canadian Arctic Archipelago, and the marginal seas (Okhotsk, Bering, East Greenland, Baffin Bay, Hudson Bay). We find that in 11 of the 12 regions (all except the Bering Sea), sea ice is retreating earlier in spring and advancing later in fall. Rates of spring retreat range from -5 to -8 days/decade, and rates of fall advance range from +5 to +9

  11. Mooring Operations for Thin-Ice Arctic Acoustic Window (THAAW) Project

    Science.gov (United States)

    2015-05-20

    including reductions in the extent and thickness of the ice cover and extensive warming of the intermediate layers. The multiyear ice is melting . Ice ...but the subsurface float was trapped beneath the ice preventing the Xeos beacon from obtaining GPS positions and transmitting Iridium messages. The...Report 3. DATES COVERED (From - To) 02/13/15-12/31/14 4. TITLE AND SUBTITLE Mooring Operations for Thin- Ice Arctic Acoustic Window (THAAW) Project

  12. Recent wind driven high sea ice export in the Fram Strait contributes to Arctic sea ice decline

    Directory of Open Access Journals (Sweden)

    L. H. Smedsrud

    2011-05-01

    Full Text Available Arctic sea ice area decrease has been visible for two decades, and continues at a steady rate. Apart from melting, the southward drift through Fram Strait is the main loss. We present high resolution sea ice drift across 79° N from 2004 to 2010. The ice drift is based on radar satellite data and correspond well with variability in local geostrophic wind. The underlying current contributes with a constant southward speed close to 5 cm s−1, and drives about 33 % of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25 % larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice export likely has a significant influence on the summer sea ice variability and we find low values in the 60's, the late 80's and 90's, and particularly high values during 2005–2008. The study highlight the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice the last decades.

  13. Filamentous phages prevalent in Pseudoalteromonas spp. confer properties advantageous to host survival in Arctic sea ice.

    Science.gov (United States)

    Yu, Zi-Chao; Chen, Xiu-Lan; Shen, Qing-Tao; Zhao, Dian-Li; Tang, Bai-Lu; Su, Hai-Nan; Wu, Zhao-Yu; Qin, Qi-Long; Xie, Bin-Bin; Zhang, Xi-Ying; Yu, Yong; Zhou, Bai-Cheng; Chen, Bo; Zhang, Yu-Zhong

    2015-03-17

    Sea ice is one of the most frigid environments for marine microbes. In contrast to other ocean ecosystems, microbes in permanent sea ice are space confined and subject to many extreme conditions, which change on a seasonal basis. How these microbial communities are regulated to survive the extreme sea ice environment is largely unknown. Here, we show that filamentous phages regulate the host bacterial community to improve survival of the host in permanent Arctic sea ice. We isolated a filamentous phage, f327, from an Arctic sea ice Pseudoalteromonas strain, and we demonstrated that this type of phage is widely distributed in Arctic sea ice. Growth experiments and transcriptome analysis indicated that this phage decreases the host growth rate, cell density and tolerance to NaCl and H2O2, but enhances its motility and chemotaxis. Our results suggest that the presence of the filamentous phage may be beneficial for survival of the host community in sea ice in winter, which is characterized by polar night, nutrient deficiency and high salinity, and that the filamentous phage may help avoid over blooming of the host in sea ice in summer, which is characterized by polar day, rich nutrient availability, intense radiation and high concentration of H2O2. Thus, while they cannot kill the host cells by lysing them, filamentous phages confer properties advantageous to host survival in the Arctic sea ice environment. Our study provides a foremost insight into the ecological role of filamentous phages in the Arctic sea ice ecosystem.

  14. Photosynthetic production in the central Arctic Ocean during the record sea-ice minimum in 2012

    NARCIS (Netherlands)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-01-01

    The ice-covered central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated

  15. Statistical indicators of Arctic sea-ice stability-prospects and limitations

    NARCIS (Netherlands)

    Bathiany, Sebastian; Bolt, van der Bregje; Williamson, Mark S.; Lenton, Timothy M.; Scheffer, Marten; Nes, van Egbert H.; Notz, Dirk

    2016-01-01

    We examine the relationship between the mean and the variability of Arctic sea-ice coverage and volume in a large range of climates from globally ice-covered to globally ice-free conditions. Using a hierarchy of two column models and several comprehensive Earth system models, we consolidate the

  16. Photosynthetic production in the central Arctic Ocean during the record sea-ice minimum in 2012

    NARCIS (Netherlands)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-01-01

    The ice-covered central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primar

  17. Statistical indicators of Arctic sea-ice stability-prospects and limitations

    NARCIS (Netherlands)

    Bathiany, Sebastian; Bolt, van der Bregje; Williamson, Mark S.; Lenton, Timothy M.; Scheffer, Marten; Nes, van Egbert H.; Notz, Dirk

    2016-01-01

    We examine the relationship between the mean and the variability of Arctic sea-ice coverage and volume in a large range of climates from globally ice-covered to globally ice-free conditions. Using a hierarchy of two column models and several comprehensive Earth system models, we consolidate the r

  18. Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming

    Science.gov (United States)

    Abe, Manabu; Nozawa, Toru; Ogura, Tomoo; Takata, Kumiko

    2016-11-01

    This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere-ocean general circulation model MIROC5. Arctic sea ice has been substantially retreating since the 1980s, particularly in September, under simulated global warming conditions. The simulated sea ice reduction is consistent with satellite observations. On the other hand, Arctic cloud cover has been increasing in October, with about a 1-month lag behind the sea ice reduction. The delayed response leads to extensive sea ice reductions because the heat and moisture fluxes from the underlying open ocean into the atmosphere are enhanced. Sensitivity experiments with the atmospheric part of MIROC5 clearly show that sea ice reduction causes increases in cloud cover. Arctic cloud cover increases primarily in the lower troposphere, but it decreases in the near-surface layers just above the ocean; predominant temperature rises in these near-surface layers cause drying (i.e., decreases in relative humidity), despite increasing moisture flux. Cloud radiative forcing due to increases in cloud cover in autumn brings an increase in the surface downward longwave radiation (DLR) by approximately 40-60 % compared to changes in clear-sky surface DLR in fall. These results suggest that an increase in Arctic cloud cover as a result of reduced sea ice coverage may bring further sea ice retreat and enhance the feedback processes of Arctic warming.

  19. Reconstructed changes in Arctic sea ice over the past 1,450 years.

    Science.gov (United States)

    Kinnard, Christophe; Zdanowicz, Christian M; Fisher, David A; Isaksson, Elisabeth; de Vernal, Anne; Thompson, Lonnie G

    2011-11-23

    Arctic sea ice extent is now more than two million square kilometres less than it was in the late twentieth century, with important consequences for the climate, the ocean and traditional lifestyles in the Arctic. Although observations show a more or less continuous decline for the past four or five decades, there are few long-term records with which to assess natural sea ice variability. Until now, the question of whether or not current trends are potentially anomalous has therefore remained unanswerable. Here we use a network of high-resolution terrestrial proxies from the circum-Arctic region to reconstruct past extents of summer sea ice, and show that-although extensive uncertainties remain, especially before the sixteenth century-both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years. Enhanced advection of warm Atlantic water to the Arctic seems to be the main factor driving the decline of sea ice extent on multidecadal timescales, and may result from nonlinear feedbacks between sea ice and the Atlantic meridional overturning circulation. These results reinforce the assertion that sea ice is an active component of Arctic climate variability and that the recent decrease in summer Arctic sea ice is consistent with anthropogenically forced warming.

  20. Arctic sea ice trends, variability and implications for seasonal ice forecasting.

    Science.gov (United States)

    Serreze, Mark C; Stroeve, Julienne

    2015-07-13

    September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with a detrended 1 year lag autocorrelation of essentially zero. We argue that through a combination of thinning and associated processes related to a warming climate (a stronger albedo feedback, a longer melt season, the lack of especially cold winters) the downward trend itself is steepening. The lack of autocorrelation manifests both the inherent large variability in summer atmospheric circulation patterns and that oceanic heat loss in winter acts as a negative (stabilizing) feedback, albeit insufficient to counter the steepening trend. These findings have implications for seasonal ice forecasting. In particular, while advances in observing sea ice thickness and assimilating thickness into coupled forecast systems have improved forecast skill, there remains an inherent limit to predictability owing to the largely chaotic nature of atmospheric variability. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  1. Transnational Sea-Ice Transport in a Warmer, More Mobile Arctic

    Science.gov (United States)

    Newton, R.; Tremblay, B.; Pfirman, S. L.; DeRepentigny, P.

    2015-12-01

    As the Arctic sea ice thins, summer ice continues to shrink in its area, and multi-year ice becomes rarer, winter ice is not disappearing from the Arctic Basin. Rather, it is ever more dominated by first year ice. And each summer, as the total coverage withdraws, the first year ice is able travel faster and farther, carrying any ice-rafted material with it. Micro-organisms, sediments, pollutants and river runoff all move across the Arctic each summer and are deposited hundreds of kilometers from their origins. Analyzing Arctic sea ice drift patterns in the context of the exclusive economic zones (EEZs) of the Arctic nations raises concerns about the changing fate of "alien" ice which forms within one country's EEZ, then drifts and melts in another country's EEZ. We have developed a new data set from satellite-based ice-drift data that allows us to track groups of ice "pixels" forward from their origin to their destination, or backwards from their melting location to their point of formation. The software has been integrated with model output to extend the tracking of sea ice to include climate projections. Results indicate, for example, that Russian sea ice dominates "imports" to the EEZ of Norway, as expected, but with increasing ice mobility it is also is exported into the EEZs of other countries, including Canada and the United States. Regions of potential conflict are identified, including several national borders with extensive and/or changing transboundary sea ice transport. These data are a starting point for discussion of transborder questions raised by "alien" ice and the material it may import from one nation's EEZ to another's.

  2. Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean

    Science.gov (United States)

    2015-06-12

    1 Title: Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean POP: 6/15/2014–6/14/2015 CDRL A002: Progress Report Technical...through April 30, 2015: $214,960 Estimate to complete: $71,245 ABSTRACT With the sea ice cover in the Arctic Ocean declining, the more...14-06-2015 4. TITLE AND SUBTITLE Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  3. New evidence for ice shelf flow across the Alaska and Beaufort margins, Arctic Ocean

    Science.gov (United States)

    Engels, Jennifer L.

    The Arctic Ocean may act as a lynchpin for global climate change due to its unique physiography as a mediterranean sea located in polar latitudes. In our modern warming climate, debate over the bounds of natural versus anthropogenically-induced climate variability necessitates a comprehensive understanding of Arctic ice extent and configuration over the last interglacial cycle. Longstanding controversy exists as to the volume, timing, and flow trajectories of ice in the Arctic Ocean during glacial maxima when continental ice sheets mantled circum-arctic landmasses. As a result of the Science Ice Exercise surveys of the Arctic Ocean in 1999, new evidence for ice grounding at depths down to 980 m on the Lomonosov Ridge and 750 m on the Chukchi Borderland indicates the likelihood that large ice shelves flowed into the ocean from both the Barents/Kara Sea and the Canadian Arctic Archipelago or eastern Alaska. Sidescan imagery of ˜14100 km2 of seafloor along the Alaska and Beaufort margins in water depths from 250--2800 m maps a repetitive association of recognizable sub-glacially generated bedforms, ice carved-bathymerry, and ice-marginal turbidite gullies over a 640 km stretch of the margin between Point Barrow and the MacKenzie River delta. Glaciogenic bedforms occur across the surface of a flattened bathymetric bench or 'second shelf break' that is interpreted to have been formed by an ice shelf eroding the continental slope. The glacial geology of surrounding areas suggests that an ice shelf on the Alaska and Beaufort margins likely flowed from the mouths of overdeepened glacial troughs in the Canadian Arctic Archipelago westward and across the Chukchi Borderland due to an obstruction in the central Canadian basin. Evidence for an ice shelf along the Alaska and Beaufort margins supports an expanded interpretation of ice volume and extent during Pleistocene glacial periods. This has far-reaching implications for Arctic climate studies, ocean circulation, sediment

  4. Apparent Arctic sea ice modeling improvement caused by volcanoes

    CERN Document Server

    Rosenblum, Erica

    2016-01-01

    The downward trend in Arctic sea ice extent is one of the most dramatic signals of climate change during recent decades. Comprehensive climate models have struggled to reproduce this, typically simulating a slower rate of sea ice retreat than has been observed. However, this bias has been substantially reduced in models participating in the most recent phase of the Coupled Model Intercomparison Project (CMIP5) compared with the previous generation of models (CMIP3). This improvement has been attributed to improved physics in the models. Here we examine simulations from CMIP3 and CMIP5 and find that simulated sea ice trends are strongly influenced by historical volcanic forcing, which was included in all of the CMIP5 models but in only about half of the CMIP3 models. The volcanic forcing causes temporary simulated cooling in the 1980s and 1990s, which contributes to raising the simulated 1979-2013 global-mean surface temperature trends to values substantially larger than observed. This warming bias is accompan...

  5. Isolation of novel psychrophilic bacteria from Arctic sea ice

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The phylogenetic diversity of culturable psychrophilic bacteria associated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated. A total of 34 psychropilic strains were isolated using three methods of (Ⅰ) dilution plating (at 4 ℃), (Ⅱ) bath culturing (at -1 ℃) and dilution plating, and (Ⅲ) cold shock (-20 ℃ for 24 h), bath culturing and dilution plating under aerobic conditions. Sea-ice samples were exposed to -20 ℃ for 24 h that might reduce the number of common microorganisms and encourage outgrowth of psychrophilic strains. This process might be able to be introduced to isolation psychrophilic bacteria from other environmental samples in future study. 16S rDNA nearly full-length sequence analysis revealed that psychrophilic strains felled in two phylogenetic divisions, γ-proteobacteria (in the genera Colwellia、Marinobacter、Shewanella、Glaciecola、Marinomonas and Pseudoalteromonas) and Cytophaga-Flexibacter-Bacteroides (Flavobacterium and Psychroflexus). Fifteen of bacterial isolates quite likely represented novel species (16S rDNA sequence similarity below 98%). One of strains (BSi20002) from Canadian Basin showed 100% sequence similarity to that of Marinobacter sp. ANT8277 isolated from the Antarctic Weddell sea ice, suggesting bacteria may have a bipolar distribution at the species level.

  6. Three recent ice entrapments of Arctic cetaceans in West Greenland and the eastern Canadian High Arctic

    Directory of Open Access Journals (Sweden)

    MP Heide-Jørgensen

    2002-07-01

    Full Text Available Three ice entrapments of Monodontids have been reported in the western North Atlantic since 1993. Hunters in Disko Bay, West Greenland, discovered one in March 1994 that included about 150 narwhals (Monodon monoceros. The entrapment occurred during a sudden cold period which caused ice to form rapidly. The trapped whales were subject to hunting, but about 50 of the killed whales could not be retrieved in the ice. The whales were trapped in a small opening in the ice and because of that they would probably have succumbed even if not discovered by hunters. Two entrapments involving white whales or belugas (Delphinapterus leucas occurred in the eastern Canadian Arctic in May 1999; one in Lancaster Sound discovered by polar bear (Ursus maritimus researchers and one in Jones Sound discovered by hunters. The first included one bowhead whale (Balaena mysticetus and about 40 belugas that were being preyed upon by polar bears. The second involved at least 170 belugas, of which about 100 were killed by polar bears and 17 were taken by hunters. The entrapments in Disko Bay and Jones Sound both occurred in areas where entrapments have previously been reported, whereas the one in Lancaster Sound was in a new area.

  7. The impact of lower sea-ice extent on Arctic greenhouse-gas exchange

    Science.gov (United States)

    Parmentier, Frans-Jan W.; Christensen, Torben R.; Sørensen, Lise Lotte; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.

    2013-01-01

    In September 2012, Arctic sea-ice extent plummeted to a new record low: two times lower than the 1979–2000 average. Often, record lows in sea-ice cover are hailed as an example of climate change impacts in the Arctic. Less apparent, however, are the implications of reduced sea-ice cover in the Arctic Ocean for marine–atmosphere CO2 exchange. Sea-ice decline has been connected to increasing air temperatures at high latitudes. Temperature is a key controlling factor in the terrestrial exchange of CO2 and methane, and therefore the greenhouse-gas balance of the Arctic. Despite the large potential for feedbacks, many studies do not connect the diminishing sea-ice extent with changes in the interaction of the marine and terrestrial Arctic with the atmosphere. In this Review, we assess how current understanding of the Arctic Ocean and high-latitude ecosystems can be used to predict the impact of a lower sea-ice cover on Arctic greenhouse-gas exchange.

  8. Acoustic Gravity Waves Generated by an Oscillating Ice Sheet in Arctic Zone

    Science.gov (United States)

    Abdolali, A.; Kadri, U.; Kirby, J. T., Jr.

    2016-12-01

    We investigate the formation of acoustic-gravity waves due to oscillations of large ice blocks, possibly triggered by atmospheric and ocean currents, ice block shrinkage or storms and ice-quakes.For the idealized case of a homogeneous weakly compressible water bounded at the surface by ice sheet and a rigid bed, the description of the infinite family of acoustic modes is characterized by the water depth h and angular frequency of oscillating ice sheet ω ; The acoustic wave field is governed by the leading mode given by: Nmax=\\floor {(ω h)/(π c)} where c is the sound speed in water and the special brackets represent the floor function (Fig1). Unlike the free-surface setting, the higher acoustic modes might exhibit a larger contribution and therefore all progressive acoustic modes have to be considered.This study focuses on the characteristics of acoustic-gravity waves generated by an oscillating elastic ice sheet in a weakly compressible fluid coupled with a free surface model [Abdolali et al. 2015] representing shrinking ice blocks in realistic sea state, where the randomly oriented ice sheets cause inter modal transition and multidirectional reflections. A theoretical solution and a 3D numerical model have been developed for the study purposes. The model is first validated against the theoretical solution [Kadri, 2016]. To overcome the computational difficulties of 3D models, we derive a depth-integrated equation valid for spatially varying ice sheet thickness and water depth. We show that the generated acoustic-gravity waves contribute significantly to deep ocean currents compared to other mechanisms. In addition, these waves travel at the sound speed in water carrying information on ice sheet motion, providing various implications for ocean monitoring and detection of ice-quakes. Fig1:Snapshots of dynamic pressure given by an oscillating ice sheet; h=4500m, c=1500m/s, semi-length b=10km, ζ =1m, omega=π rad/s. Abdolali, A., Kirby, J. T. and Bellotti, G

  9. Interactions Between Microphysics and Dynamics in Persistent Arctic Mixed Phase Clouds

    Science.gov (United States)

    Komurcu, M.; Harrington, J. Y.

    2011-12-01

    Mixed-phase clouds are commonly observed in the Arctic atmosphere, particularly during the transition and winter seasons. Inter-comparison of the results of the model simulations of cold season mixed-phase clouds show that the biggest spreads in model results occur in the simulated water contents which lead to negative radiation errors. Partitioning of the liquid water and ice is crucial in understanding the radiative influences of these clouds, and in turn their influences on the Arctic surface energy budget. Because ice growth occurs at the expense of liquid water droplets at cold temperatures of the Arctic during the cold season, the phase partitioning of water is partly controlled by the ice formation and growth processes. Therefore, in this study, we investigate and intercompare different ice formation mechanisms, ice crystal shapes and the number of available ice nuclei to understand the microphysical and dynamical interactions that allow for the formation and persistence of both liquid water and ice in long-lived mixed-phase clouds. We present results that attempt to separate the influences of microphysics and dynamics, with a view to understanding how dynamic processes affect the production and maintenance of supercooled liquid within Arctic cloud systems. We investigate how certain conditions that influence cloud circulations, such as changing the magnitudes of surface fluxes, or radiative forcing, can lead to the decoupling of the cloud and subcloud layers, and in turn possibly to the cessation of the cloud. To identify the conditions of decoupling, we develop a new ratio based on cloud circulations that is different from previous assessments of decoupling in the literature, which did not seem to work for Arctic clouds.

  10. Microphysical sensitivity of coupled springtime Arctic stratocumulus to modelled primary ice over the ice pack, marginal ice, and ocean

    Science.gov (United States)

    Young, Gillian; Connolly, Paul J.; Jones, Hazel M.; Choularton, Thomas W.

    2017-03-01

    This study uses large eddy simulations to test the sensitivity of single-layer mixed-phase stratocumulus to primary ice number concentrations in the European Arctic. Observations from the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign are considered for comparison with cloud microphysics modelled using the Large Eddy Model (LEM, UK Met. Office). We find that cloud structure is very sensitive to ice number concentrations, Nice, and small increases can cause persisting mixed-phase clouds to glaciate and break up.Three key dependencies on Nice are identified from sensitivity simulations and comparisons with observations made over the sea ice pack, marginal ice zone (MIZ), and ocean. Over sea ice, we find deposition-condensation ice formation rates are overestimated, leading to cloud glaciation. When ice formation is limited to water-saturated conditions, we find microphysics comparable to aircraft observations over all surfaces considered. We show that warm supercooled (-13 °C) mixed-phase clouds over the MIZ are simulated to reasonable accuracy when using both the DeMott et al.(2010) and Cooper(1986) primary ice nucleation parameterisations. Over the ocean, we find a strong sensitivity of Arctic stratus to Nice. The Cooper(1986) parameterisation performs poorly at the lower ambient temperatures, leading to a comparatively higher Nice (2.43 L-1 at the cloud-top temperature, approximately -20 °C) and cloud glaciation. A small decrease in the predicted Nice (2.07 L-1 at -20 °C), using the DeMott et al.(2010) parameterisation, causes mixed-phase conditions to persist for 24 h over the ocean. However, this representation leads to the formation of convective structures which reduce the cloud liquid water through snow precipitation, promoting cloud break-up through a depleted liquid phase. Decreasing the Nice further (0.54 L-1, using a relationship derived from ACCACIA observations) allows mixed-phase conditions to be maintained for at

  11. Recent Trends in the Arctic Navigable Ice Season and Links to Atmospheric Circulation

    Science.gov (United States)

    Maslanik, J.; Drobot, S.

    2002-12-01

    One of the potential effects of Arctic climate warming is an increase in the navigable ice season, perhaps resulting in development of the Arctic as a major shipping route. The distance from western North American ports to Europe through the Northwest Passage (NWP) or the Northern Sea Route (NSR) is typically 20 to 60 percent shorter than travel through the Panama Canal, while travel between Europe and the Far East may be reduced by as much as three weeks compared to transport through the Suez Canal. An increase in the navigable ice season would also improve commercial opportunities within the Arctic region, such as mineral and oil exploration and tourism, which could potentially expand the economic base of Arctic residents and companies, but which would also have negative environmental impacts. Utilizing daily passive-microwave derived sea ice concentrations, trends and variability in the Arctic navigable ice season are examined from 1979 through 2001. Trend analyses suggest large increases in the length of the navigable ice season in the Kara and Barents seas, the Sea of Okhotsk, and the Beaufort Sea, with decreases in the length of the navigable ice season in the Bering Sea. Interannual variations in the navigable ice season largely are governed by fluctuations in low-frequency atmospheric circulation, although the specific annular modes affecting the length of the navigable ice season vary by region. In the Beaufort and East Siberian seas, variations in the North Atlantic Oscillation/Arctic Oscillation control the navigable ice season, while variations in the East Pacific anomaly play an important role in controlling the navigable ice season in the Kara and Barents seas. In Hudson Bay, the Canadian Arctic Archipelago, and Baffin Bay, interannual variations in the navigable ice season are strongly related to the Pacific Decadal Oscillation.

  12. Simulated Annual and Seasonal Arctic Ocean and Sea-Ice Variability From a High Resolution, Coupled Ice-Ocean Model

    Science.gov (United States)

    2001-09-01

    influence heat transfer to the surface, impacting polynya formation, ice melt, and ice growth. 13 Wang et al. (1994) presented results from a sigma level...Longmans, Green and Co., 1902. Nansen, F., Northern water: Captain Roald Amundsen’s oceanographic observations in the Arctic Seas in 1901...

  13. Intercomparison of the Arctic sea ice cover in global ocean-sea ice reanalyses from the ORA-IP project

    Science.gov (United States)

    Chevallier, Matthieu; Smith, Gregory C.; Dupont, Frédéric; Lemieux, Jean-François; Forget, Gael; Fujii, Yosuke; Hernandez, Fabrice; Msadek, Rym; Peterson, K. Andrew; Storto, Andrea; Toyoda, Takahiro; Valdivieso, Maria; Vernieres, Guillaume; Zuo, Hao; Balmaseda, Magdalena; Chang, You-Soon; Ferry, Nicolas; Garric, Gilles; Haines, Keith; Keeley, Sarah; Kovach, Robin M.; Kuragano, Tsurane; Masina, Simona; Tang, Yongming; Tsujino, Hiroyuki; Wang, Xiaochun

    2017-08-01

    Ocean-sea ice reanalyses are crucial for assessing the variability and recent trends in the Arctic sea ice cover. This is especially true for sea ice volume, as long-term and large scale sea ice thickness observations are inexistent. Results from the Ocean ReAnalyses Intercomparison Project (ORA-IP) are presented, with a focus on Arctic sea ice fields reconstructed by state-of-the-art global ocean reanalyses. Differences between the various reanalyses are explored in terms of the effects of data assimilation, model physics and atmospheric forcing on properties of the sea ice cover, including concentration, thickness, velocity and snow. Amongst the 14 reanalyses studied here, 9 assimilate sea ice concentration, and none assimilate sea ice thickness data. The comparison reveals an overall agreement in the reconstructed concentration fields, mainly because of the constraints in surface temperature imposed by direct assimilation of ocean observations, prescribed or assimilated atmospheric forcing and assimilation of sea ice concentration. However, some spread still exists amongst the reanalyses, due to a variety of factors. In particular, a large spread in sea ice thickness is found within the ensemble of reanalyses, partially caused by the biases inherited from their sea ice model components. Biases are also affected by the assimilation of sea ice concentration and the treatment of sea ice thickness in the data assimilation process. An important outcome of this study is that the spatial distribution of ice volume varies widely between products, with no reanalysis standing out as clearly superior as compared to altimetry estimates. The ice thickness from systems without assimilation of sea ice concentration is not worse than that from systems constrained with sea ice observations. An evaluation of the sea ice velocity fields reveals that ice drifts too fast in most systems. As an ensemble, the ORA-IP reanalyses capture trends in Arctic sea ice area and extent

  14. On large outflows of Arctic sea ice into the Barents Sea

    Science.gov (United States)

    Kwok, Ron; Maslowski, Wieslaw; Laxon, Seymour W.

    2005-01-01

    Winter outflows of Arctic sea ice into the Barents Sea are estimated using a 10-year record of satellite ice motion and thickness. The mean winter volume export through the Svalbard/Franz Josef Land passage is 40 km3, and ranges from -280 km3 to 340 km3. A large outflow in 2003 is preconditioned by an unusually high concentration of thick perennial ice over the Nansen Basin at the end of the 2002 summer. With a deep atmospheric low situated over the eastern Barents Sea in winter, the result is an increased export of Arctic ice. The Oct-Mar ice area flux, at 110 x 10 to the third power km3, is not only unusual in magnitude but also remarkable in that >70% of the area is multiyear ice; the ice volume flux at340 km3 is almost one-fifth of the ice flux through the Fram Strait. Another large outflow of Arctic sea ice through this passage, comparable to that in 2003, is found in 1996. This southward flux of sea ice represents one of two major sources of freshwater in the Barents Sea; the other is the eastward flux of water via the Norwegian Coastal Current. The possible consequences of variable freshwater input on the Barents Sea hydrography and its impact on transformation of Atlantic Water en route to the Arctic Ocean are examined with a 25-year coupled ice-ocean model.

  15. A Possible Feedback Mechanism Involving the Arctic Freshwater,the Arctic Sea Ice, and the North Atlantic Drift

    Institute of Scientific and Technical Information of China (English)

    Odd Helge OTTER(A); Helge DRANGE

    2004-01-01

    Model studies point to enhanced warming and to increased freshwater fluxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined effect of increased freshwater input to the Arctic Ocean and Arctic warming--the latter manifested as a gradual melting of the Arctic sea ice--is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runoff, and a third more extreme case, where the river runoff is five times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5-2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift.Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensified Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.

  16. Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

    Science.gov (United States)

    2013-09-30

    ice age, and iv) onset dates of melt and freezeup . 4. Assess the magnitude of the contribution from ice-albedo feedback to the observed decrease of...the impact on albedo evolution of ice concentration and melt and freezeup onset dates. This effort will expand on previous work by i) examining...radiation, ice concentration, ice type, and melt and freezeup onset dates on a 25 x 25 km equal area scalable grid. We have daily values of these parameters

  17. Influence of Sea Ice on the Thermohaline Circulation in the Arctic-North Atlantic Ocean

    Science.gov (United States)

    Mauritzen, Cecilie; Haekkinen, Sirpa

    1997-01-01

    A fully prognostic coupled ocean-ice model is used to study the sensitivity of the overturning cell of the Arctic-North-Atlantic system to sea ice forcing. The strength of the thermohaline cell will be shown to depend on the amount of sea ice transported from the Arctic to the Greenland Sea and further to the subpolar gyre. The model produces a 2-3 Sv increase of the meridional circulation cell at 25N (at the simulation year 15) corresponding to a decrease of 800 cu km in the sea ice export from the Arctic. Previous modeling studies suggest that interannual and decadal variability in sea ice export of this magnitude is realistic, implying that sea ice induced variability in the overturning cell can reach 5-6 Sv from peak to peak.

  18. Short-term sea ice forecasting: An assessment of ice concentration and ice drift forecasts using the U.S. Navy's Arctic Cap Nowcast/Forecast System

    Science.gov (United States)

    Hebert, David A.; Allard, Richard A.; Metzger, E. Joseph; Posey, Pamela G.; Preller, Ruth H.; Wallcraft, Alan J.; Phelps, Michael W.; Smedstad, Ole Martin

    2015-12-01

    In this study the forecast skill of the U.S. Navy operational Arctic sea ice forecast system, the Arctic Cap Nowcast/Forecast System (ACNFS), is presented for the period February 2014 to June 2015. ACNFS is designed to provide short term, 1-7 day forecasts of Arctic sea ice and ocean conditions. Many quantities are forecast by ACNFS; the most commonly used include ice concentration, ice thickness, ice velocity, sea surface temperature, sea surface salinity, and sea surface velocities. Ice concentration forecast skill is compared to a persistent ice state and historical sea ice climatology. Skill scores are focused on areas where ice concentration changes by ±5% or more, and are therefore limited to primarily the marginal ice zone. We demonstrate that ACNFS forecasts are skilful compared to assuming a persistent ice state, especially beyond 24 h. ACNFS is also shown to be particularly skilful compared to a climatologic state for forecasts up to 102 h. Modeled ice drift velocity is compared to observed buoy data from the International Arctic Buoy Programme. A seasonal bias is shown where ACNFS is slower than IABP velocity in the summer months and faster in the winter months. In February 2015, ACNFS began to assimilate a blended ice concentration derived from Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Interactive Multisensor Snow and Ice Mapping System (IMS). Preliminary results show that assimilating AMSR2 blended with IMS improves the short-term forecast skill and ice edge location compared to the independently derived National Ice Center Ice Edge product.

  19. Present and Future Surface Mass Budget of Small Arctic Ice Caps in a High Resolution Regional Climate Model

    Science.gov (United States)

    Mottram, Ruth; Langen, Peter; Koldtoft, Iben; Midefelt, Linnea; Hesselbjerg Christensen, Jens

    2016-04-01

    Globally, small ice caps and glaciers make a substantial contribution to sea level rise; this is also true in the Arctic. Around Greenland small ice caps are surprisingly important to the total mass balance from the island as their marginal coastal position means they receive a large amount of precipitation and also experience high surface melt rates. Since small ice caps and glaciers have had a disproportionate number of long-term monitoring and observational schemes in the Arctic, likely due to their relative accessibility, they can also be a valuable source of data. However, in climate models the surface mass balance contributions are often not distinguished from the main ice sheet and the presence of high relief topography is difficult to capture in coarse resolution climate models. At the same time, the diminutive size of marginal ice masses in comparison to the ice sheet makes modelling their ice dynamics difficult. Using observational data from the Devon Ice Cap in Arctic Canada and the Renland Ice Cap in Eastern Greenland, we assess the success of a very high resolution (~5km) regional climate model, HIRHAM5 in capturing the surface mass balance (SMB) of these small ice caps. The model is forced with ERA-Interim and we compare observed mean SMB and the interannual variability to assess model performance. The steep gradient in topography around Renland is challenging for climate models and additional statistical corrections are required to fit the calculated surface mass balance to the high relief topography. Results from a modelling experiment at Renland Ice Cap shows that this technique produces a better fit between modelled and observed surface topography. We apply this statistical relationship to modelled SMB on the Devon Ice Cap and use the long time series of observations from this glacier to evaluate the model and the smoothed SMB. Measured SMB values from a number of other small ice caps including Mittivakkat and A.P. Olsen ice cap are also compared

  20. The ASIBIA sea-ice facility: First results from the Atmosphere-Sea-Ice-Biogeochemistry in the Arctic chamber

    Science.gov (United States)

    France, James L.; Thomas, Max

    2016-04-01

    Working in the natural ocean-ice-atmosphere system is very difficult, as conducting fieldwork on sea-ice presents many challenges ice including costs, safety, experimental controls and access. The new ASIBIA (Atmosphere-Sea-Ice-Biogeochemistry in the Arctic) coupled Ocean-Sea-Ice-(Snow)-Atmosphere chamber facility at the University of East Anglia, UK, we are aiming to perform controlled first-year sea-ice investigations in areas such as sea-ice physics, physicochemical and biogeochemical processes in sea-ice and quantification of the bi-directional flux of gases in various states of first-year sea-ice conditions. The facility is a medium sized chamber with programmable temperatures from -55°C to +30°C, allowing a full range of first year sea-ice growing conditions in both the Arctic and Antarctic to be simulated. The water depth can be up to 1 m (including up to 25 cm of sea-ice) and an optional 1 m tall Teflon film atmosphere on top of the sea-ice, thus creating a closed and coupled ocean-sea-ice-atmosphere mesocosm. Ice growth in the tank is well suited for studying first-year sea-ice physical properties, with in-situ ice-profile measurements of temperature, salinity, conductivity, pressure and spectral light transmission. Underwater and above ice cameras are installed to record the physical development of the sea-ice. Here, we present the data from the first suites of experiments in the ASIBIA chamber focussing on sea-ice physics and give a brief description of the capabilities of the facility going forward. The ASIBIA chamber was funded as part of an ERC consolidator grant to the late Prof. Roland von Glasow and we hope this work and further development of the facility will act as a lasting legacy.

  1. A Pan-Arctic Network to Study Past, Present, and Future Sea Ice Trends

    Science.gov (United States)

    Wegner, Carolyn; Frey, Karen E.; Michel, Christine

    2011-03-01

    Arctic in Rapid Transition Implementation Workshop; Winnipeg, Manitoba, Canada, 18-20 October 2010 ; Rapid transitions in Arctic sea ice and the associated global integrated Earth system impacts and socioeconomic consequences have brought the Arctic Ocean to the top of national and international geophysical and political agendas. Alarmingly, there is a persistent mismatch between observed and predicted patterns, which speaks to the complexity of planning adaptation and mitigation activities in the Arctic. Predicting future conditions of Arctic marine ecosystems for climate change requires interdisciplinary and pan-Arctic characterization and understanding of past and present trends. The Arctic in Rapid Transition (ART) initiative is an integrative, international, interdisciplinary, pan-Arctic network to study spatial and temporal changes in sea ice cover and ocean circulation over broad time scales to better understand and forecast the impact of these changes on Arctic marine ecosystems and biogeochemistry. The ART initiative began in October 2008 and is still led by early-career scientists. The ART science plan, developed after the ART initiation workshop in November 2009, was endorsed by the Arctic Ocean Sciences Board, which is now the Marine Working Group of the International Arctic Science Committee.

  2. The impact of regional Arctic sea ice loss on atmospheric circulation and the NAO

    Science.gov (United States)

    Anker Pedersen, Rasmus; Cvijanovic, Ivana; Langen, Peter Lang; Vinther, Bo

    2016-04-01

    Reduction of the Arctic sea ice cover can affect the atmospheric circulation, and thus impact the climate beyond the Arctic. The atmospheric response may, however, vary with the geographical location of sea ice loss. The atmospheric sensitivity to the location of sea ice loss is studied using a general circulation model in a configuration that allows combination of a prescribed sea ice cover and an active mixed layer ocean. This hybrid setup makes it possible to simulate the isolated impact of sea ice loss and provides a more complete response compared to experiments with fixed sea surface temperatures. Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming which peaks over the area of ice loss. The maximum warming is found during winter, delayed compared to the maximum sea ice reduction. The wintertime response of the mid-latitude atmospheric circulation shows a non-uniform sensitivity to the location of sea ice reduction. While all three scenarios exhibit decreased zonal winds related to high-latitude geopotential height increases, the magnitudes and locations of the anomalies vary between the simulations. Investigation of the North Atlantic Oscillation reveals a high sensitivity to the location of the ice loss. The northern center of action exhibits clear shifts in response to the different sea ice reductions. Sea ice loss in the Atlantic and Pacific sectors of the Arctic cause westward and eastward shifts, respectively.

  3. "Rotten Ice": Characterizing the Physical Properties of Arctic Sea Ice Under Conditions of Extreme Summer Melt

    Science.gov (United States)

    Light, B.; Frantz, C. M.; Junge, K.; Orellana, M. V.; Carpenter, S.; Farley, S. M.; Lieb-Lappen, R.; Courville, Z.

    2016-12-01

    The microstructural properties of sea ice are central to understanding the mechanical, thermal, electrical, and optical properties of a sea ice cover. Over the course of an annual cycle, this small scale structure routinely evolves from a network of mostly isolated brine and gas inclusions prevalent in cold ice, to a more connected, more permeable structure as the ice endures summer melt processes. In the case of extreme summer melt, sea ice can become "rotten", and it is expected that such rotten ice may become more prevalent as melt seasons lengthen. Rotten ice is approximately isothermal, largely drained of brine, and is typified by the presence of large multi-cm-scale void spaces that contribute to its high permeability and low structural integrity. These properties are expected to alter the ice cover response to dynamic forcing, ability to backscatter incident light, and its melt rate. An interdisciplinary effort to characterize the physical properties of rotten first-year ice, in concert with some of its chemical and biological properties, is being carried out both in the field and in the laboratory. Time-series samples focusing on the evolution of ice microstructure were acquired and analyzed for shore-fast first-year sea ice near Barrow, Alaska in May - July of 2015. Laboratory studies have focused on assessing the seasonal evolution of optical properties of this ice, as well as the measurement of melt rates of ice grown under carefully controlled laboratory conditions. Preliminary results from these studies illuminate some of the physical and biophysical controls on late summer ice melt.

  4. Sea Ice Charts of the Russian Arctic in Gridded Format, 1933-2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia, produces sea ice charts for safety of navigation in the polar regions and for other...

  5. Changing Arctic ecosystems: sea ice decline, permafrost thaw, and benefits for geese

    Science.gov (United States)

    Flint, Paul; Whalen, Mary; Pearce, John M.

    2014-01-01

    Through the Changing Arctic Ecosystems (CAE) initiative, the U.S. Geological Survey (USGS) strives to inform resource management decisions for Arctic Alaska by providing scientific information on current and future ecosystem response to a warming climate. A key area for the USGS CAE initiative has been the Arctic Coastal Plain of northern Alaska. This region has experienced a warming trend over the past 30 years, leading to reductions in sea ice and thawing of permafrost. Loss of sea ice has increased ocean wave action, leading to erosion and salt water inundation of coastal habitats. Saltwater tolerant plants are now thriving in these areas and this appears to be a positive outcome for geese in the Arctic. This finding is contrary to the deleterious effects that declining sea ice is having on habitats of ice-dependent animals, such as polar bear and walrus.

  6. Recent Changes in Arctic Ocean Sea Ice Motion Associated with the North Atlantic Oscillation

    Science.gov (United States)

    Kwok, R.

    1999-01-01

    Examination of a new ice motion dataset of the Arctic Ocean over a recent eighteen year period (1978-1996) reveals patterns of variability that can be linked directly to the North Atlantic Oscillation.

  7. Hydrological role of large icings within glacierized Sub-Arctic watershed: case study in Upper Duke River valley, Yukon, Canada.

    Science.gov (United States)

    Chesnokova, Anna; Baraer, Michel

    2017-04-01

    Sub-Arctic glacierized catchments are complex hydrological systems of paramount importance for water resources management as well as for various ecosystem services. Such systems host many climate-sensitive water sources. Among those, icing is an important component as they provide substantial amount of water during the melt season. Moreover, collecting water of different origins during their formation, icings can be seen as an indicator for different water sources and water pathways that remain active during the freezing period. The present study focuses on genesis and dynamics of large icings within both proglacial field and neighboring alpine meadow in Upper Duke River valley, Yukon, in order to i) provide new insights on water sources and pathways within Sub-Arctic glacierized watersheds, and ii) to quantify contribution of icings to the total runoff of those hydrological systems. A multi-approach technique was applied to cope with the high hydrological complexity met in Sub-Arctic mountainous environments. Time series of positions of large river icings within the study area were obtained using Landsat images for the period 1980-2016. Four time-lapse cameras (TLC) were installed in the watershed targeting two proglacial fields and two alpine meadows in order to monitor icing dynamics all year long. Meteorological data was measured by an Automatic Weather Station in the main valley. In addition air temperature and relative humidity were measured at the location of each TLC. Finally, four icings along the Duke River valley, as well as 2 icings in its main tributary were sampled for stable water isotopes, solutes concentrations and total organic carbon. In addition, samples of freezing exclusion precipitates from icing surfaces were taken. Remote sensing data shows the persistence of large icing complexes in the area during last 30 years: icing within proglacial field appear with almost constant position relative to main glacier tongue on the 30 years long period

  8. Characteristics of Arctic Ocean ice determined from SMMR data for 1979 - Case studies in the seasonal sea ice zone

    Science.gov (United States)

    Anderson, M. R.; Crane, R. G.; Barry, R. G.

    1985-01-01

    Sea ice data derived from the Scanning Multichannel Microwave Radiometer are examined for sections of the Arctic Ocean during early summer 1979. The temporary appearance of spuriously high multiyear ice fractions in the seasonal ice zones of the Kara and Barents Seas is a result of surface melt phenomena and the relative responses of the different channels to these effects. These spurious signatures can provide early identification of melt onset and additional information on surface characteristics.

  9. Future Arctic marine access: analysis and evaluation of observations, models, and projections of sea ice

    Directory of Open Access Journals (Sweden)

    T. S. Rogers

    2013-02-01

    Full Text Available There is an emerging need for regional applications of sea ice projections to provide more accuracy and greater detail to scientists, national, state and local planners, and other stakeholders. The present study offers a prototype for a comprehensive, interdisciplinary study to bridge observational data, climate model simulations, and user needs. The study's first component is an observationally based evaluation of Arctic sea ice trends during 1980–2008, with an emphasis on seasonal and regional differences relative to the overall pan-Arctic trend. Regional sea ice loss has varied, with a significantly larger decline of winter maximum (January–March extent in the Atlantic region than in other sectors. A lead–lag regression analysis of Atlantic sea ice extent and ocean temperatures indicates that reduced sea ice extent is associated with increased Atlantic Ocean temperatures. Correlations between the two variables are greater when ocean temperatures lag rather than lead sea ice. The performance of 13 global climate models is evaluated using three metrics to compare sea ice simulations with the observed record. We rank models over the pan-Arctic domain and regional quadrants and synthesize model performance across several different studies. The best performing models project reduced ice cover across key access routes in the Arctic through 2100, with a lengthening of seasons for marine operations by 1–3 months. This assessment suggests that the Northwest and Northeast Passages hold potential for enhanced marine access to the Arctic in the future, including shipping and resource development opportunities.

  10. Future Arctic marine access: analysis and evaluation of observations, models, and projections of sea ice

    Directory of Open Access Journals (Sweden)

    T. S. Rogers

    2012-09-01

    Full Text Available There is an emerging need for regional applications of sea ice projections to provide more accuracy and greater detail to scientists, national, state and local planners, and other stakeholders. The present study offers a prototype for a comprehensive, interdisciplinary study to bridge observational data, climate model simulations, and user needs. The study's first component is an observationally-based evaluation of Arctic sea ice trends during 1980–2008, with an emphasis on seasonal and regional differences relative to the overall pan-Arctic trend. Regional sea ice los has varied, with a significantly larger decline of winter maximum (January–March extent in the Atlantic region than in other sectors. A lead-lag regression analysis of Atlantic sea ice extent and ocean temperatures indicates that reduced sea ice extent is associated with increased Atlantic Ocean temperatures. Correlations between the two variables are greater when ocean temperatures lag rather than lead sea ice. The performance of 13 global climate models is evaluated using three metrics to compare sea ice simulations with the observed record. We rank models over the pan-Arctic domain and regional quadrants, and synthesize model performance across several different studies. The best performing models project reduced ice cover across key access routes in the Arctic through 2100, with a lengthening of seasons for marine operations by 1–3 months. This assessment suggests that the Northwest and Northeast Passages hold potential for enhanced marine access to the Arctic in the future, including shipping and resource development opportunities.

  11. Measurements of bubble size spectra within leads in the Arctic summer pack ice

    NARCIS (Netherlands)

    Norris, S.J.; Brooks, I.M.; Leeuw, G. de; Sirevaag, A.; Leck, C.; Brooks, B.J.; Birch, C.E.; Tjernström, M.

    2011-01-01

    The first measurements of bubble size spectra within the near-surface waters of open leads in the central Arctic pack ice were obtained during the Arctic Summer Cloud-Ocean Study (ASCOS) in August 2008 at 87-87.6° N, 1-11° W. A significant number of small bubbles (30-100 μm diameter) were present, w

  12. Recent and future changes of the Arctic sea-ice cover

    OpenAIRE

    Smedsrud, Lars Henrik; Sorteberg, Asgeir; Kloster, Kjell

    2008-01-01

    The present and future state of the Arctic sea ice cover is explored using new observations and a coupled one dimensional air–sea–ice model. Updated satellite observations of Fram Strait ice-area export show an increase over the last four years, with 37% increase in winter 07–08. Atmospheric poleward energy flux declined since 1990, but advection of oceanic heat has recently increased. Simulations show that the ice area export is a stronger driver of thinning than the...

  13. Snow Cover on the Arctic Sea Ice: Model Validation, Sensitivity, and 21st Century Projections

    Science.gov (United States)

    Blazey, Benjamin Andrew

    The role of snow cover in controlling Arctic Ocean sea ice thickness and extent is assessed with a series of models. Investigations with the stand alone Community Ice CodE (CICE) show, first, a reduction in snow depth triggers a decrease in ice volume and area, and, second, that the impact of increased snow is heavily dependent on ice and atmospheric conditions. Hindcast snow depths on the Arctic ice, simulated by the fully coupled Community Climate System Model (CCSM) are validated with 20th century in situ snow depth measurements. The snow depths in CCSM are found to be deeper than observed, likely due to excessive precipitation produced by the component atmosphere model. The sensitivity of the ice to the thermal barrier imposed by the biased snow depth is assessed. The removal of the thermodynamic impact of the exaggerated snow depth increases ice area and volume. The initial increases in ice due to enhanced conductive flux triggers feedback mechanisms with the atmosphere and ocean, reinforcing the increase in ice. Finally, the 21st century projections of decreased Arctic Ocean snow depth in CCSM are reported and diagnosed. The changes in snow are dominated by reduced accumulation due to the lack of autumn ice cover. Without this platform, much of the early snowfall is lost directly to the ocean. While this decrease in snow results in enhanced conductive flux through the ice as in the validation sensitivity experiment, the decreased summer albedo is found to dominate, as in the CICE stand alone sensitivity experiment. As such, the decrease in snow projected by CCSM in the 21st century presents a mechanism to continued ice loss. These negative (ice growth due decreased insulation) and positive (ice melt due to decreased albedo) feedback mechanisms highlight the need for an accurate representation snow cover on the ice in order to accurately simulate the evolution of Arctic Ocean sea ice.

  14. Recent and future changes of the Arctic sea-ice cover

    OpenAIRE

    Smedsrud, Lars Henrik; Sorteberg, Asgeir; Kloster, Kjell

    2008-01-01

    The present and future state of the Arctic sea ice cover is explored using new observations and a coupled one dimensional air–sea–ice model. Updated satellite observations of Fram Strait ice-area export show an increase over the last four years, with 37% increase in winter 07–08. Atmospheric poleward energy flux declined since 1990, but advection of oceanic heat has recently increased. Simulations show that the ice area export is a stronger driver of thinning than the...

  15. Methane and Root Dynamics in Arctic Soil

    DEFF Research Database (Denmark)

    D'Imperio, Ludovica

    on the global climate. We investigated two aspects of arctic ecosystem dynamics which are not well represented in climatic models: i) soil methane (CH4) oxidation in dry heath tundra and barren soils and ii) root dynamics in wetlands. Field measurements were carried out during the growing season in Disko Island......, West Greenland, and CH4 and root dynamics were assessed in response to experimentally increased winter snow precipitation, summer warming and their interaction to better understand their contribution to the C balance of the Arctic. Our results indicate that both the dry heath and barren soils have...... from wetlands in a future warmer climate. At the wet fen increased winter snow precipitation delayed the onset of the growing season of about a week and reduced the relative fine root production. The use of minirhizotrons improved our understanding of root growth and phenology. Total root number...

  16. Derive Arctic Sea-ice Freeboard and Thickness from NASA's LVIS Observations

    Science.gov (United States)

    Yi, D.; Hofton, M. A.; Harbeck, J.; Cornejo, H.; Kurtz, N. T.

    2015-12-01

    The sea-ice freeboard and thickness are derived from the six sea-ice flights of NASA's IceBridge Land, Vegetation, and Ice Sensor (LVIS) over the Arctic from 2009 to 2013. The LVIS is an airborne scanning laser altimeter. It can operate at an altitude up to 10 km above the ground and produce a data swath up to 2 km wide with 20-m wide footprints. The laser output wavelength is 1064 nm and pulse repetition rate is 1000 Hz. The LVIS L2 geolocated surface elevation product and Level-1b waveform product (http://nsidc.org/data/ilvis2.html and http://nsidc.org/data/ilvis1b.html) at National Snow and Ice Data Center, USA (NSIDC) are used in this study. The elevations are referenced to a geoid with tides and dynamic atmospheric corrections applied. The LVIS waveforms were fitted with Gaussian curves to calculate pulse width, peak location, pulse amplitude, and signal baseline. For each waveform, the centroid, skewness, kurtosis, and pulse area were also calculated. The waveform parameters were calibrated based on laser off pointing angle and laser channels. Calibrated LVIS waveform parameters show a coherent response to variations in surface features along their ground tracks. These parameters, combined with elevation, can be used to identify leads, enabling the derivation of sea-ice freeboard and thickness without relying upon visual images. Preliminary results show that the elevations in some of the LVIS campaigns may vary with laser incident angle; this can introduce an elevation bias if not corrected. Further analysis of the LVIS data shown that the laser incident angle related elevation bias can be removed empirically. The sea-ice freeboard and thickness results from LVIS are compared with NASA's Airborne Topographic Mapper (ATM) for an April 20, 2010 flight, when both LVIS and ATM sensors were on the same aircraft and made coincidental measurements along repeat ground tracks.

  17. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using

  18. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using we

  19. Ice cores from Arctic sub-polar glaciers : Chronology and post-depositional processes deduced from radioactivity measurements

    NARCIS (Netherlands)

    Pinglot, J.F.; Vaikmae, R.A.; Kamiyama, K.; Igarashi, M.; Fritsche, D.; Wilhalms, F.; Koerner, R.; Henderson, L.; Isaksson, E.; Winther, J.G.; van de Wal, R.S.W.; Fournier, M; Bouisset, P.; Meijer, H.A.J.

    2003-01-01

    The response of Arctic ice masses to climate change is studied using ice cores containing information on past climatic and environmental features. Interpretation of this information requires accurate chronological data. Absolute dating of ice cores from sub-polar Arctic glaciers is possible using we

  20. Warming in the Nordic Seas, North Atlantic storms and thinning Arctic sea ice

    Science.gov (United States)

    Alexeev, Vladimir A.; Walsh, John E.; Ivanov, Vladimir V.; Semenov, Vladimir A.; Smirnov, Alexander V.

    2017-08-01

    Arctic sea ice over the last few decades has experienced a significant decline in coverage both in summer and winter. The currently warming Atlantic Water layer has a pronounced impact on sea ice in the Nordic Seas (including the Barents Sea). More open water combined with the prevailing atmospheric pattern of airflow from the southeast, and persistent North Atlantic storms such as the recent extremely strong Storm Frank in December 2015, lead to increased energy transport to the high Arctic. Each of these storms brings sizeable anomalies of heat to the high Arctic, resulting in significant warming and slowing down of sea ice growth or even melting. Our analysis indicates that the recently observed sea ice decline in the Nordic Seas during the cold season around Svalbard, Franz Joseph Land and Novaya Zemlya, and the associated heat release from open water into the atmosphere, contributed significantly to the increase in the downward longwave radiation throughout the entire Arctic. Added to other changes in the surface energy budget, this increase since the 1960s to the present is estimated to be at least 10 W m-2, which can result in thinner (up to at least 15-20 cm) Arctic ice at the end of the winter. This change in the surface budget is an important contributing factor accelerating the thinning of Arctic sea ice.

  1. Ice Processes and Growth History on Arctic and Sub-Arctic Lakes Using ERS-1 SAR Data

    Science.gov (United States)

    Morris, K.; Jeffries, M. O.; Weeks, W. F.

    1995-01-01

    A survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period ot ice cover (September to June) for the years 1991-1992 and 1992-1993. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

  2. Effectiveness and Sensitivity of the Arctic Observing Network in a Coupled Ocean-Sea Ice State Estimation Framework

    Science.gov (United States)

    Nguyen, A. T.; Heimbach, P.; Garg, V.; Ocana, V.

    2016-12-01

    Over the last few decades, various agencies have invested heavily in the development and deployment of Arctic ocean and sea ice observing platforms, especially moorings, profilers, gliders, and satellite-based instruments. These observational assets are heterogeneous in terms of variables sampled and spatio-temporal coverage, which calls for a dynamical synthesis framework of the diverse data streams. Here we introduce an adjoint-based Arctic Subpolar gyre sTate estimate (ASTE), a medium resolution model-data synthesis that leverages all the possible observational assets. Through an established formal state and parameter estimation framework, the ASTE framework produces a 2002-present ocean-sea ice state that can be used to address Arctic System science questions. It is dynamically and kinematically consistent with known equations of motion and consistent with observations. Four key aspects of ASTE will be discussed: (1) How well is ASTE constrained by the existing observations; (2) which data most effectively constrain the system, and what impact on the solution does spatial and temporal coverage have; (3) how much information does one set of observation (e.g. Fram Strait heat transport) carry about a remote, but dynamically linked component (e.g. heat content in the Beaufort Gyre); and (4) how can the framework be used to assess the value of hypothetical observations in constraining poorly observed parts of the Arctic Ocean and the implied mechanisms responsible for the changes occurring in the Arctic. We will discuss the suggested geographic distribution of new observations to maximize the impact on improving our understanding of the general circulation, water mass distribution and hydrographic changes in the Arctic.

  3. Shifting El Niño inhibits summer Arctic warming and Arctic sea-ice melting over the Canada Basin

    Science.gov (United States)

    Hu, Chundi; Yang, Song; Wu, Qigang; Li, Zhenning; Chen, Junwen; Deng, Kaiqiang; Zhang, Tuantuan; Zhang, Chengyang

    2016-06-01

    Arctic climate changes include not only changes in trends and mean states but also strong interannual variations in various fields. Although it is known that tropical-extratropical teleconnection is sensitive to changes in flavours of El Niño, whether Arctic climate variability is linked to El Niño, in particular on interannual timescale, remains unclear. Here we demonstrate for the first time a long-range linkage between central Pacific (CP) El Niño and summer Arctic climate. Observations show that the CP warming related to CP El Niño events deepens the tropospheric Arctic polar vortex and strengthens the circumpolar westerly wind, thereby contributing to inhibiting summer Arctic warming and sea-ice melting. Atmospheric model experiments can generally capture the observed responses of Arctic circulation and robust surface cooling to CP El Niño forcing. We suggest that identification of the equator-Arctic teleconnection, via the `atmospheric bridge', can potentially contribute to improving the skill of predicting Arctic climate.

  4. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    Science.gov (United States)

    Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

    2016-01-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial.

  5. Wind-driven mixing at intermediate depths in an ice-free Arctic Ocean

    Science.gov (United States)

    Lincoln, Ben J.; Rippeth, Tom P.; Lenn, Yueng-Djern; Timmermans, Mary Louise; Williams, William J.; Bacon, Sheldon

    2016-09-01

    Recent seasonal Arctic Ocean sea ice retreat is a major indicator of polar climate change. The Arctic Ocean is generally quiescent with the interior basins characterized by low levels of turbulent mixing at intermediate depths. In contrast, under conditions of reduced sea ice cover, there is evidence of energetic internal waves that have been attributed to increased momentum transfer from the atmosphere to the ocean. New measurements made in the Canada Basin during the unusually ice-free and stormy summer of 2012 show previously observed enhancement of internal wave energy associated with ice-free conditions. However, there is no enhancement of mixing at intermediate depths away from significant topography. This implies that contrary to expectations of increased wind-induced mixing under declining Arctic sea ice cover, the stratification in the central Canada Basin continues to suppress turbulent mixing at intermediate depths and to effectively isolate the large Atlantic and Pacific heat reservoirs from the sea surface.

  6. Does a relationship between Arctic low clouds and sea ice matter?

    Science.gov (United States)

    Taylor, Patrick C.

    2017-02-01

    Arctic low clouds strongly affect the Arctic surface energy budget. Through this impact Arctic low clouds influence important aspects of the Arctic climate system, namely surface and atmospheric temperature, sea ice extent and thickness, and atmospheric circulation. Arctic clouds are in turn influenced by these elements of the Arctic climate system, and these interactions create the potential for Arctic cloud-climate feedbacks. To further our understanding of potential Arctic cloud-climate feedbacks, the goal of this paper is to quantify the influence of atmospheric state on the surface cloud radiative effect (CRE) and its covariation with sea ice concentration (SIC). We build on previous research using instantaneous, active remote sensing satellite footprint data from the NASA A-Train. First, the results indicate significant differences in the surface CRE when stratified by atmospheric state. Second, there is a weak covariation between CRE and SIC for most atmospheric conditions. Third, the results show statistically significant differences in the average surface CRE under different SIC values in fall indicating a 3-5 W m-2 larger LW CRE in 0% versus 100% SIC footprints. Because systematic changes on the order of 1 W m-2 are sufficient to explain the observed long-term reductions in sea ice extent, our results indicate a potentially significant amplifying sea ice-cloud feedback, under certain meteorological conditions, that could delay the fall freeze-up and influence the variability in sea ice extent and volume. Lastly, a small change in the frequency of occurrence of atmosphere states may yield a larger Arctic cloud feedback than any cloud response to sea ice.

  7. Measurements of sea ice thickness and its subice morphology analysis using ice-penetration radar in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    孙波; 邓新生; 康建成; 罗宇忠; 温家洪; 李院生

    2003-01-01

    Based on radar penetrating measurements and analysis of sea ice in the Arctic Ocean, The potential of radar wave to measure sea ice thickness and map the morphology of the underside of sea ice is investigated.The results indicate that the radar wave can penetrate Arctic summer sea ice of over 6 meters thick; and the propagation velocity of the radar wave in sea ice is in the range of 0.142 m*ns-1 to 0.154 m*ns-1.The radar images display the roughness and micro-relief variation of sea ice bottom surface.These features are closely related to sea ice types, which show that radar survey may be used to identify and classify ice types.Since radar images can simultaneously display the linear profile features of both the upper surface and the underside of sea ice, we use these images to quantify their actual linear length discrepancy.A new length factor is suggested in relation to the actual linear length discrepancy in linear profiles of sea ice, which may be useful in further study of the area difference between the upper surface and bottom surface of sea ice.

  8. Changes in the modeled ice thickness distribution near the Surface Heat Budget of the Arctic Ocean (SHEBA) drifting ice camp

    Science.gov (United States)

    Lindsay, R. W.

    2003-06-01

    In the polar oceans the ice thickness distribution controls the exchange of heat between the ocean and the atmosphere and determines the strength of the ice. The Surface Heat Budget of the Arctic Ocean (SHEBA) experiment included a year-long field program centered on a drifting ice station in the Beaufort and Chukchi Seas in the Arctic Ocean from October 1997 through October 1998. Here we use camp observations and develop methods to assimilate ice thickness and open water observations into a model in order to estimate the evolution of the thickness distribution in the vicinity of the camp. A thermodynamic model is used to simulate the ice growth and melt, and an ice redistribution model is used to simulate the opening and ridging processes. Data assimilation procedures are developed and then used to assimilate observations of the thickness distribution. Assimilated observations include those of the thin end of the distribution determined by aircraft surveys of the surface temperature and helicopter photographic surveys and aircraft microwave estimates of the open water fraction. The deformation of the ice was determined primarily from buoy and RADARSAT Geophysical Processor System (RGPS) measurements of the ice velocity. Because of the substantial convergence and ridging observed in the spring and summer, the estimated mean ice thickness increases by 59%, from 1.53 to 2.44 m, over the year in spite of a net thermodynamic ice loss for most multiyear ice.

  9. Mercury distribution and transport across the ocean-sea-ice-atmosphere interface in the Arctic Ocean.

    Science.gov (United States)

    Chaulk, Amanda; Stern, Gary A; Armstrong, Debbie; Barber, David G; Wang, Feiyue

    2011-03-01

    The Arctic sea-ice environment has been undergoing dramatic changes in the past decades; to which extent this will affect the deposition, fate, and effects of chemical contaminants remains virtually unknown. Here, we report the first study on the distribution and transport of mercury (Hg) across the ocean-sea-ice-atmosphere interface in the Southern Beaufort Sea of the Arctic Ocean. Despite being sampled at different sites under various atmospheric and snow cover conditions, Hg concentrations in first-year ice cores were generally low and varied within a remarkably narrow range (0.5-4 ng L(-1)), with the highest concentration always in the surface granular ice layer which is characterized by enriched particle and brine pocket concentration. Atmospheric Hg depletion events appeared not to be an important factor in determining Hg concentrations in sea ice except for frost flowers and in the melt season when snowpack Hg leaches into the sea ice. The multiyear ice core showed a unique cyclic feature in the Hg profile with multiple peaks potentially corresponding to each ice growing/melting season. The highest Hg concentrations (up to 70 ng L(-1)) were found in sea-ice brine and decrease as the melt season progresses. As brine is the primary habitat for microbial communities responsible for sustaining the food web in the Arctic Ocean, the high and seasonally changing Hg concentrations in brine and its potential transformation may have a major impact on Hg uptake in Arctic marine ecosystems under a changing climate.

  10. Trends and variability in summer sea ice cover in the Canadian Arctic based on the Canadian Ice Service Digital Archive

    Science.gov (United States)

    Howell, S.; Tivy, A. C.; Alt, B.; McCourt, S.; Chagnon, R.; Crocker, G.; Carrieres, T. G.; Yackel, J.

    2010-12-01

    The Canadian Ice Service Digital Archive (CISDA) is a compilation of weekly ice charts that cover Canadian Waters; the data set is continually updated and it extends back to the early 1960s. The ice charts are represent and integration of remotely sensed sea ice data, surface observations, airborne and ship reports, operational model results and the expertise of experience ice forecasters. Although the accuracy, type and detail of information far exceeds what is attainable from a single satellite source, errors and uncertainties in the data are non-uniform in both space and time. In part one of this study the main sources of uncertainty in the database are reviewed and the data are validated for use in climate studies. In part two, trends and variability in summer sea ice in the Canadian Arctic are investigated using CISDA. These data revealed that between 1968 and 2008, summer sea ice cover has decreased by 8.9% ± 3.1% per decade in Hudson Bay, 2.9% ± 1.2% per decade in the Canadian Arctic Archipelago, 8.9% ± 3.1% per decade in Baffin Bay, and 5.2% ± 2.4% per decade in the Beaufort Sea. In general, these reductions in sea ice cover are linked to increases in early summer surface air temperature (SAT); significant increases in SAT were observed in every season and with the exception of the Hudson Bay region they are consistently greater than the pan-Arctic change by up to ~0.2oC per decade. Within the Canadian Arctic Archipelago and Baffin Bay, the El Niño-Southern Oscillation (ENSO) index correlates well with multi-year ice coverage (positive correlation) and first-year ice coverage (negative correlation) suggesting that El Nino episodes precede summers with more multi-year ice and less first-year ice. Extending the trend calculations back to 1960 along the major shipping routes through the Canadian Arctic revealed significant decreases in summer sea ice coverage ranging between 11% and 15% per decade along the shipping route through Hudson Bay, the western

  11. Projected changes in regional climate extremes arising from Arctic sea ice loss

    Science.gov (United States)

    Screen, James A.; Deser, Clara; Sun, Lantao

    2015-08-01

    The decline in Arctic sea ice cover has been widely documented and it is clear that this change is having profound impacts locally. An emerging and highly uncertain area of scientific research, however, is whether such Arctic change has a tangible effect on weather and climate at lower latitudes. Of particular societal relevance is the open question: will continued Arctic sea ice loss make mid-latitude weather more extreme? Here we analyse idealized atmospheric general circulation model simulations, using two independent models, both forced by projected Arctic sea ice loss in the late twenty-first century. We identify robust projected changes in regional temperature and precipitation extremes arising solely due to Arctic sea ice loss. The likelihood and duration of cold extremes are projected to decrease over high latitudes and over central and eastern North America, but to increase over central Asia. Hot extremes are projected to increase in frequency and duration over high latitudes. The likelihood and severity of wet extremes are projected to increase over high latitudes, the Mediterranean and central Asia; and their intensity is projected to increase over high latitudes and central and eastern Asia. The number of dry days over mid-latitude Eurasia and dry spell duration over high latitudes are both projected to decrease. There is closer model agreement for projected changes in temperature extremes than for precipitation extremes. Overall, we find that extreme weather over central and eastern North America is more sensitive to Arctic sea ice loss than over other mid-latitude regions. Our results are useful for constraining the role of Arctic sea ice loss in shifting the odds of extreme weather, but must not be viewed as deterministic projections, as they do not account for drivers other than Arctic sea ice loss.

  12. On the sensitivity of undeformed Arctic sea ice to its vertical salinity profile

    OpenAIRE

    Vancoppenolle, M.; Fichefet, T.; C. M. Bitz

    2005-01-01

    The temporal evolution of sea ice salinity affects the temperature profile and vertical growth and decay of the ice cover, as well as many other important properties. Here, we use a one-dimensional thermodynamic sea ice model to explore the sensitivity to the vertical profile of ice salinity of (1) Arctic first-year and equilibrium multiyear sea ice thickness, and (2) the salt/freshwater flux at the ice/ocean interface. Results indicate that increasing the mean salinity induces a higher therm...

  13. Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

    Directory of Open Access Journals (Sweden)

    A. Kriegsmann

    2013-03-01

    Full Text Available This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration on the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important reasons for the recent ice extent minima in 2007 and 2012.

  14. Quantifying the contribution of natural variability to September Arctic sea ice decline

    Institute of Scientific and Technical Information of China (English)

    SONG Mirong; WEI Lixin; WANG Zhenzhan

    2016-01-01

    Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trends in the forced and unforced simulations of carefully selected global climate models with the extended observed Arctic sea ice records. The results suggest that the natural variability explains no more than 42.3% of the observed September sea ice extent trend during 35 a (1979–2013) satellite observations, which is comparable to the results of the observed sea ice record extended back to 1953 (61 a, less than 48.5% natural variability). This reinforces the evidence that anthropogenic forcing plays a substantial role in the observed decline of September Arctic sea ice in recent decades. The magnitude of both positive and negative trends induced by the natural variability in the unforced simulations is slightly enlarged in the context of increasing greenhouse gases in the 21st century. However, the ratio between the realizations of positive and negative trends change has remained steady, which enforces the standpoint that external forcing will remain the principal determiner of the decreasing Arctic sea ice extent trend in the future.

  15. Sea ice leads in the Arctic Ocean: Model assessment, interannual variability and trends

    Science.gov (United States)

    Wang, Q.; Danilov, S.; Jung, T.; Kaleschke, L.; Wernecke, A.

    2016-07-01

    Sea ice leads in the Arctic are important features that give rise to strong localized atmospheric heating; they provide the opportunity for vigorous biological primary production, and predicting leads may be of relevance for Arctic shipping. It is commonly believed that traditional sea ice models that employ elastic-viscous-plastic (EVP) rheologies are not capable of properly simulating sea ice deformation, including lead formation, and thus, new formulations for sea ice rheologies have been suggested. Here we show that classical sea ice models have skill in simulating the spatial and temporal variation of lead area fraction in the Arctic when horizontal resolution is increased (here 4.5 km in the Arctic) and when numerical convergence in sea ice solvers is considered, which is frequently neglected. The model results are consistent with satellite remote sensing data and discussed in terms of variability and trends of Arctic sea ice leads. It is found, for example, that wintertime lead area fraction during the last three decades has not undergone significant trends.

  16. Airborne observations of changes of ice sheet and sea ice in the Arctic using CryoVEx campaign data

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Skourup, Henriette; Forsberg, René

    DTU Space have collected surface elevation observations of the Arctic sea ice and land ice since 1998 using laser scanning and radar altimetry from a small fixed‐wing Twin‐Otter aircraft. The observations provide unique datasets for studying ongoing changes, and support the analysis of satellite......‐launch validation studies, with several aircraft and international in‐situ ground teams participating, both in Greenland, Arctic Canada, and Svalbard. The methods and campaigns are outlined together with examples of results.The campaigns focused on five main validation sites: Devon ice cap (Canada), Austfonna ice...... measurements of ice sheet changes. The majority of the campaigns have been sponsored by the European Space Agency, ESA, as part of the CryoSat Validation Experiments – CryoVEx. These have been internationally coordinated efforts to collect coincident space‐borne, airborne, and in‐situ data for pre‐ and post...

  17. Impacts of Organic Macromolecules, Chlorophyll and Soot on Arctic Sea Ice

    Science.gov (United States)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Flanner, M.; Dubey, M. K.

    2014-12-01

    Recent intensification of Arctic amplification can be strongly connected to positive feedback relating black carbon deposition to sea ice surface albedo. In addition to soot deposition on the ice and snow pack, ice algal chlorophyll is likely to compete as an absorber and redistributor of energy. Hence, solar radiation absorption by chlorophyll and some components of organic macromolecules in/under the ice column is currently being examined to determine the level of influence on predicted rate of ice loss. High amounts of organic macromolecules and chlorophyll are produced in global sea ice by the bottom microbial community and also in vertically distributed layers where substantial biological activities take place. Brine channeling in columnar ice can allow for upward flow of nutrients which leads to greater primary production in the presence of moderate light. Modeling of the sea-ice processes in tandem with experiments and field observations promises rapid progress in enhancing Arctic ice predictions. We are designing and conducting global climate model experiments to determine the impact of organic macromolecules and chlorophyll on Arctic sea ice. Influences on brine network permeability and radiation/albedo will be considered in this exercise. Absorption by anthropogenic materials such as soot and black carbon will be compared with that of natural pigments. We will indicate areas of soot and biological absorption dominance in the sense of single scattering, then couple into a full radiation transfer scheme to attribute the various contributions to polar climate change amplification. The work prepares us to study more traditional issues such as chlorophyll warming of the pack periphery and chemical effects of the flow of organics from ice internal communities. The experiments started in the Arctic will broaden to include Antarctic sea ice and shelves. Results from the Arctic simulations will be presented.

  18. Arctic Ocean Sea Ice Thickness, Bathymetry, and Water Properties from Submarine Data

    Science.gov (United States)

    Windnagel, A. K.; Fetterer, F. M.

    2014-12-01

    The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration that began in 1993 among the operational Navy, research agencies, and the marine research community to use nuclear-powered submarines for scientific studies of the Arctic Ocean. Unlike surface ships and satellites, submarines have the unique ability to operate and take measurements regardless of sea ice cover, weather conditions, and time of year. This allows for a broad and comprehensive investigation of an entire ocean basin. The goal of the program is to acquire comprehensive data about Arctic sea ice thickness; biological, chemical, and hydrographic water properties; and bathymetry to improve our understanding of the Arctic Ocean basin and its role in the Earth's climate system. Ice draft is measured with upward looking sonars mounted on the submarine's hull. The work of collaborators on the SCICEX project compared recent ice draft from the submarines with draft from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) and with ice thickness estimates from ice age and have shown that SCICEX ice draft are consistent with these models. Bathymetry is measured with a bottom sounder. SCICEX bathymetry data from 1993 to 1999 are included in the International Bathymetric Chart of the Arctic Ocean (IBCAO). Collaborators have compared more recent bathymetry data collected through the SCICEX project with other IBCAO data, and they agree well. Water properties are measured with two different types of conductivity, temperature, and depth (CTD) sensors: one mounted on the submarine's hull and expendable versions that are deployed through the submarines torpedo tubes. Data from the two different CTD sensors validate one another. The breadth of instrumentation available from submarines along with their ability to be unencumbered by sea ice, weather, and season makes the data they have collected extremely valuable. The National Snow and Ice Data Center (NSIDC) manages this data

  19. Use of Declassified High-Resolution Imagery and Coincident Data Sets for Characterizing the Changing Arctic Ice Cover, and Collaboration with SIZRS

    Science.gov (United States)

    2015-09-30

    Arctic Ocean sea ice cover . OBJECTIVES Literal Image Derived...imagery for understanding of sea ice processes of the Arctic Ocean sea ice cover . RELATED PROJECTS Developing Remote Sensing Capabilities for...Coincident Data Sets for Characterizing the Changing Arctic Ice Cover , and Collaboration with SIZRS” R. Kwok Jet Propulsion Laboratory

  20. Numerical simulations of the current state of waters and sea ice in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    E. N. Golubeva

    2015-01-01

    Full Text Available The paper presents results of numerical simulation of variability of the sea ice area and water circulation in the Arctic Ocean performed with use of the atmosphere reanalysis data for the period from middle of the last century to the present time. The model results reflect the ocean responses to changes of the atmosphere circulation regimes that manifests in changes of trajectories of waters coming into the Arctic Ocean from the Pacific and Atlantic oceans. The model results show influence of the Pacific and Atlantic waters on distribution and thickness of the Arctic ice

  1. The role of mechanics and kinematics on the Arctic sea ice decline

    Science.gov (United States)

    Weiss, J.

    2011-12-01

    IPCC AR4 climate models unforeseen the recent Arctic sea ice decline, either in terms of extent or thinning rate. Owing to the complexity of the Arctic basin as a physical system involving many interacting processes and feedbacks (negative or positive), several tracks are currently followed to try to improve the representation of these processes. Here we focus on the representation of sea ice mechanics and kinematics (drift, deformation). Indeed, the spectacular evolution of the Arctic sea ice cover is not restricted to the shrinking of ice extent or to thinning. Kinematics is affected as well, and its evolution plays a central role in the changes underwent nowadays in the Arctic ocean. As observed from buoy drift data, the sea ice mean speed increased at a rate of 9% per decade from 1979 to 2007, whereas the mean deformation rate increased by more than 50% per decade over the same period. These two aspects of recent sea ice evolution, i.e. strong decline and accelerated kinematics, are likely intimately coupled. Increasing deformation means stronger fracturing, hence more lead opening and a decreasing albedo. As a result, ocean warming, in turn, favors sea ice thinning in summer and delays refreezing in early winter, i.e. strengthens sea ice decline. This thinning decreases the mechanical strength, therefore allowing even more fracturing, hence larger speed and deformation. A consequence is the acceleration of sea ice export through Fram or Nares Strait with a significant impact on sea ice mass balance. The coupling between the ice state (thickness and concentration) and ice velocity is unexpectedly weak in most IPCC AR4 models. In particular, sea ice drifts faster during the months when it is thick and packed than when it is thin, contrary to what is observed; also models with larger long-term thinning trends do not show higher drift acceleration. This weak coupling behavior (i) suggests that the positive feedbacks mentioned above are underestimated, and (ii) can

  2. Diversity and characterization of mercury-resistant bacteria in snow, freshwater and sea-ice brine from the High Arctic.

    Science.gov (United States)

    Møller, Annette K; Barkay, Tamar; Abu Al-Soud, Waleed; Sørensen, Søren J; Skov, Henrik; Kroer, Niels

    2011-03-01

    It is well-established that atmospheric deposition transports mercury from lower latitudes to the Arctic. The role of bacteria in the dynamics of the deposited mercury, however, is unknown. We characterized mercury-resistant bacteria from High Arctic snow, freshwater and sea-ice brine. Bacterial densities were 9.4 × 10(5), 5 × 10(5) and 0.9-3.1 × 10(3) cells mL(-1) in freshwater, brine and snow, respectively. Highest cultivability was observed in snow (11.9%), followed by freshwater (0.3%) and brine (0.03%). In snow, the mercury-resistant bacteria accounted for up to 31% of the culturable bacteria, but Arctic food chains.

  3. Ice–ocean coupled computations for sea-ice prediction to support ice navigation in Arctic sea routes

    Directory of Open Access Journals (Sweden)

    Liyanarachchi Waruna Arampath De Silva

    2015-11-01

    Full Text Available With the recent rapid decrease in summer sea ice in the Arctic Ocean extending the navigation period in the Arctic sea routes (ASR, the precise prediction of ice distribution is crucial for safe and efficient navigation in the Arctic Ocean. In general, however, most of the available numerical models have exhibited significant uncertainties in short-term and narrow-area predictions, especially in marginal ice zones such as the ASR. In this study, we predict short-term sea-ice conditions in the ASR by using a mesoscale eddy-resolving ice–ocean coupled model that explicitly treats ice floe collisions in marginal ice zones. First, numerical issues associated with collision rheology in the ice–ocean coupled model (ice–Princeton Ocean Model [POM] are discussed and resolved. A model for the whole of the Arctic Ocean with a coarser resolution (about 25 km was developed to investigate the performance of the ice–POM model by examining the reproducibility of seasonal and interannual sea-ice variability. It was found that this coarser resolution model can reproduce seasonal and interannual sea-ice variations compared to observations, but it cannot be used to predict variations over the short-term, such as one to two weeks. Therefore, second, high-resolution (about 2.5 km regional models were set up along the ASR to investigate the accuracy of short-term sea-ice predictions. High-resolution computations were able to reasonably reproduce the sea-ice extent compared to Advanced Microwave Scanning Radiometer–Earth Observing System satellite observations because of the improved expression of the ice–albedo feedback process and the ice–eddy interaction process.

  4. The effect of changing sea ice on the physical vulnerability of Arctic coasts

    Directory of Open Access Journals (Sweden)

    K. R. Barnhart

    2014-09-01

    Full Text Available Sea ice limits the interaction of the land and ocean water in the Arctic winter and influences this interaction in the summer by governing the fetch. In many parts of the Arctic, the open-water season is increasing in duration and summertime sea-ice extents are decreasing. Sea ice provides a first-order control on the physical vulnerability of Arctic coasts to erosion, inundation, and damage to settlements and infrastructures by ocean water. We ask how the changing sea-ice cover has influenced coastal erosion over the satellite record. First, we present a pan-Arctic analysis of satellite-based sea-ice concentration specifically along the Arctic coasts. The median length of the 2012 open-water season, in comparison to 1979, expanded by between 1.5 and 3-fold by Arctic Sea sector, which allows for open water during the stormy Arctic fall. Second, we present a case study of Drew Point, Alaska, a site on the Beaufort Sea, characterized by ice-rich permafrost and rapid coastal-erosion rates, where both the duration of the open-water season and distance to the sea-ice edge, particularly towards the northwest, have increased. At Drew Point, winds from the northwest result in increased water levels at the coast and control the process of submarine notch incision, the rate-limiting step of coastal retreat. When open-water conditions exist, the distance to the sea ice edge exerts control on the water level and wave field through its control on fetch. We find that the extreme values of water-level setup have increased consistently with increasing fetch.

  5. Future increases in Arctic precipitation linked to local evaporation and sea-ice retreat.

    Science.gov (United States)

    Bintanja, R; Selten, F M

    2014-05-22

    Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation.

  6. Observational determination of albedo decrease caused by vanishing Arctic sea ice.

    Science.gov (United States)

    Pistone, Kristina; Eisenman, Ian; Ramanathan, V

    2014-03-04

    The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m(2) of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming.

  7. The sensitivity of Arctic sea ice production to shelf flooding during the early Holocene: a modelling study

    Science.gov (United States)

    Blaschek, M.; Renssen, H.

    2012-04-01

    During the last deglaciation, the global sea-level started rising, changing the coastlines from an early Holocene stand (40 m lower than today at approximately 10 kyr BP, Siddall et al., 2003) to modern day coastlines. Proxy evidence shows that this transgression occurred non-uniformly over the globe. For instance, Bauch et al. (2001) report for the Laptev Sea (Arctic Ocean), that the modern coastline was only established at 5 kyr BP after a fast transgression from the early Holocene, leading to a flooding of the extensive shelf area. This shelf area is presently regarded to be an important production zone of Arctic sea ice, playing an important role in the dynamics of sea ice in the Arctic, as well as its export to the Nordic Seas along the East Greenland Current (EGC). Through this sea ice export, changes in the Laptev Sea shelf area during the Holocene could potentially have had a substantial impact on the sea surface conditions of the EGC, and the Denmark Strait, which is known to be sensitive to sea ice. This is consistent with a rapid increase in sea ice export through the EGC around 5 kyr BP as reported by Jennings et al. (2002). In this study we investigate the impact of this Arctic shelf flooding on sea ice production in the Holocene, and on the climate of the Nordic Seas in the LOVECLIM1.2 global ocean-atmosphere-vegetation model. We present results of several experiments in which we study the sensitivity of Arctic sea ice production to various Arctic shelf areas under early Holocene conditions (9 kyr BP). We approach this by changing the land-sea mask to represent different lower-than-present sea-level coastlines. For example, we perform experiments with the Last Glacial Maximum (LGM) land-sea mask, representing a lowering of the sea-level by 120 m, while keeping other forcings at 9 kyr BP. A further step is to modify selected areas in the Arctic, such as the Laptev Sea area, to examine the importance of different areas. Our results help to explain long

  8. Tracking the Arctic's Shrinking Ice Cover: Another Extreme Minimum in 2004.

    Science.gov (United States)

    Stroeve, J. C.; Fetterer, F.; Knowles, K.; Meier, W.; Serreze, M.; Arbetter, T.

    2004-12-01

    Of all the recent observed changes in the Arctic environment, the reduction of sea ice cover stands out most prominantly. Several independent analysis have established a trend in Arctic ice extent of -3% per decade from the late 1970s to the late 1990s, with a more pronounced trend in summer. The overall downward trend is characterized by strong interannual variability, with a low September ice extent in one year typically followed by recovery the next September. Having two extreme minimum years, such as what was observed in 2002 and 2003 is unusual. 2004 marks the third year in a row of substantially below normal sea ice cover in the Arctic. Early summer 2004 appeared unusual in terms of ice extent, with May a record low for the satellite period (1979-present) and June also exhibiting below normal ice extent. August 2004 extent is below that of 2003 and large reductions in ice cover are observed once again off the coasts of Siberia and Alaska and the Greenland Sea. Neither the 2002 or 2003 anomaly appeared to be strongly linked to the positive phase of the Arctic Oscillation (AO) during the preceding winter. Similarly, the AO was negative during winter 2003/2004. In the previous AO framework of Rigor et al (2002), a positive winter AO implied preconditioning of the ice cover to extensive summer decay. In this hypothesis, the AO does not explain all aspects of the recent decline in Arctic ice cover, such as the extreme minima of 2002, 2003 and 2004. New analysis by Rigor and Wallace (2004) suggest that the very positive AO state from 1989-1995 can explain the recent sea ice minima in terms of reductions in the overall age of ice driven by the previous high AO state. However, it is also reasonable to expect that a general decrease in ice thickness accompanying warming would manifest itself as greater sensitivity of the ice pack to wind forcings and albedo feedbacks. The decrease in multiyear ice and attendant changes in ice thickness distribution could in turn

  9. Historical variations of mercury stable isotope ratios in Arctic glacier firn and ice cores

    Science.gov (United States)

    Zdanowicz, C. M.; Krümmel, E. M.; Poulain, A. J.; Yumvihoze, E.; Chen, J.; Å trok, M.; Scheer, M.; Hintelmann, H.

    2016-09-01

    The concentration and isotopic composition of mercury (Hg) were determined in glacier core samples from Canadian Arctic ice caps dating from preindustrial to recent time (early 21st century). Mean Hg levels increased from ≤ 0.2 ng L-1 in preindustrial time to ~0.8-1.2 ng L-1 in the modern industrial era (last ~200 years). Hg accumulated on Arctic ice caps has Δ199Hg and Δ201Hg that are higher (~ -1 to 2.9‰) than previously reported for Arctic snow impacted by atmospheric Hg depletion events (mostly < -1‰), suggesting that these events contribute little to Hg accumulation on ice caps. The range of δ202Hg, Δ199Hg, and Δ201Hg in glacier cores overlaps with that of Arctic Hg0(g) and of seawater in Baffin Bay and also with that of midlatitude precipitation and industrial Hg sources, including coal and Hg ores. A core from Agassiz ice cap (80.7°N) shows a ~ +1‰ shift in δ202Hg over the nineteenth to twentieth centuries that could reflect changes in the isotopic composition of the atmospheric Hg pool in the High Arctic in response to growing industrial emissions at lower latitudes. This study is the first ever to report on historical variations of Hg stable isotope ratios in Arctic ice cores. Results could help constrain future modeling efforts of the global Hg biogeochemical cycle and the atmosphere's response to changing Hg emissions, past and future.

  10. Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

    DEFF Research Database (Denmark)

    Forsberg, René; Skourup, Henriette

    2005-01-01

    ICESat laser measurements provide a high-resolution mapping of the sea-ice surface of the Arctic Ocean, which can be inverted to determine gravity anomalies and sea-ice freeboard heights by a "lowest-level'' filtering scheme. In this paper we use updated terrestrial gravity data from the Arctic...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....... Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...

  11. Linking the northern hemisphere sea-ice reduction trend and the quasi-decadal arctic sea-ice oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. [University of Alaska Fairbanks, International Arctic Research Center, Alaska (United States); Ikeda, M. [Hokkaido University, Graduate School of Environmental Earth Science, Sapporo (Japan); Zhang, S. [University of Alaska Fairbanks Fairbanks, Department of Mathematical Sciences, Alaska (United States); Gerdes, R. [Alfred-Wegener Institute for Polar Research, Bremerhaven (Germany)

    2005-02-01

    The nature of the reduction trend and quasi-decadal oscillation in Northern Hemisphere sea-ice extent is investigated. The trend and oscillation that seem to be two separate phenomena have been found in data. This study examines a hypothesis that the Arctic sea-ice reduction trend in the last three decades amplified the quasi-decadal Arctic sea-ice oscillation (ASIO) due to a positive ice/ocean-albedo feedback, based on data analysis and a conceptual model proposed by Ikeda et al. The theoretical, conceptual model predicts that the quasi-decadal oscillation is amplified by the thinning sea-ice, leading to the ASIO, which is driven by the strong positive feedback between the atmosphere and ice-ocean systems. Such oscillation is predicted to be out-of-phase between the Arctic Basin and the Nordic Seas with a phase difference of 3{pi}/4, with the Nordic Seas leading the Arctic. The wavelet analysis of the sea ice data reveals that the quasi-decadal ASIO occurred actively since the 1970s following the trend starting in the 1960s (i.e., as sea-ice became thinner and thinner), as the atmosphere experienced quasi-decadal oscillations during the last century. The wavelet analysis also confirms the prediction of such out-of-phase feature between these two basins, which varied from 0.62{pi} in 1960 to 0.25{pi} in 1995. Furthermore, a coupled ice-ocean general circulation model (GCM) was used to simulate two scenarios, one without the greenhouse gas warming and the other having realistic atmospheric forcing along with the warming that leads to sea-ice reduction trend. The quasi-decadal ASIO is excited in the latter case compared to the no-warming case. The wavelet analyses of the simulated ice volume were also conducted to derive decadal ASIO and similar phase relationship between the Arctic Ocean and the Nordic Seas. An independent data source was used to confirm such decadal oscillation in the upper layer (or freshwater) thickness, which is consistent with the model

  12. Modified PIC Method for Sea Ice Dynamics

    Institute of Scientific and Technical Information of China (English)

    WANG Rui-xue; JI Shun-ying; SHEN Hung-tao; YUE Qian-jin

    2005-01-01

    The sea ice cover displays various dynamical characteristics such as breakup, rafting, and ridging under external forces. To model the ice dynamic process accurately, the effective numerical modeling method should be established. In this paper, a modified particle-in-cell (PIC) method for sea ice dynamics is developed coupling the finite difference (FD) method and smoothed particle hydrodynamics (SPH). In this method, the ice cover is first discretized into a series of Lagrangian ice particles which have their own sizes, thicknesses, concentrations and velocities. The ice thickness and concentration at Eulerian grid positions are obtained by interpolation with the Gaussian function from their surrounding ice particles. The momentum of ice cover is solved with FD approach to obtain the Eulerian cell velocity, which is used to estimate the ice particle velocity with the Gaussian function also. The thickness and concentration of ice particles are adjusted with particle mass density and smooth length, which are adjusted with the redistribution of ice particles. With the above modified PIC method, numerical simulations for ice motion in an idealized rectangular basin and the ice dynamics in the Bohai Sea are carried out. These simulations show that this modified PIC method is applicable to sea ice dynamics simulation.

  13. Exopolymer alteration of physical properties of sea ice and implications for ice habitability and biogeochemistry in a warmer Arctic.

    Science.gov (United States)

    Krembs, Christopher; Eicken, Hajo; Deming, Jody W

    2011-03-01

    The physical properties of Arctic sea ice determine its habitability. Whether ice-dwelling organisms can change those properties has rarely been addressed. Following discovery that sea ice contains an abundance of gelatinous extracellular polymeric substances (EPS), we examined the effects of algal EPS on the microstructure and salt retention of ice grown from saline solutions containing EPS from a culture of the sea-ice diatom, Melosira arctica. We also experimented with xanthan gum and with EPS from a culture of the cold-adapted bacterium Colwellia psychrerythraea strain 34H. Quantitative microscopic analyses of the artificial ice containing Melosira EPS revealed convoluted ice-pore morphologies of high fractal dimension, mimicking features found in EPS-rich coastal sea ice, whereas EPS-free (control) ice featured much simpler pore geometries. A heat-sensitive glycoprotein fraction of Melosira EPS accounted for complex pore morphologies. Although all tested forms of EPS increased bulk ice salinity (by 11-59%) above the controls, ice containing native Melosira EPS retained the most salt. EPS effects on ice and pore microstructure improve sea ice habitability, survivability, and potential for increased primary productivity, even as they may alter the persistence and biogeochemical imprint of sea ice on the surface ocean in a warming climate.

  14. Arctic Sea Ice Reemergence: The Role of Large-Scale Oceanic and Atmospheric Variability

    Science.gov (United States)

    Bushuk, M.; Giannakis, D.; Majda, A.

    2014-12-01

    Arctic sea ice reemergence is a phenomenon in which spring sea ice anomalies are positively correlated with fall anomalies, despite a loss of correlation over the intervening summer months. Pan-Arctic sea ice reemergence is present in both observations and global climate models (GCMs), yet the amplitude and regional details of the reemergence signals vary substantially. In this work, a novel data analysis technique, coupled Nonlinear Laplacian Spectral Analysis (NLSA), is employed to study the spatiotemporal co-variability of sea ice concentration, sea surface temperature (SST), and sea level pressure (SLP) in the Arctic. NLSA modes are obtained for observational data and GCM output, and are used to examine the statistical characteristics and physical mechanisms of sea ice reemergence. It is found that lagged correlation features of the raw sea ice data can be efficiently reproduced using low-dimensional families of modes. These families provide an SST-sea ice reemergence mechanism, in which melt season (spring) sea ice anomalies are imprinted as SST anomalies and stored over the summer months, allowing for sea ice anomalies of the same sign to reappear in the growth season (fall). Moreover, the ice anomalies of each family exhibit clear phase relationships between the Barents-Kara, Bering, and Labrador seas. These regional phase relationships have a natural explanation via the SLP patterns and associated geostrophic winds of each family, which closely resemble the Arctic Oscillation and Arctic Dipole Anomaly. Additionally, the winter-to-winter persistence of these SLP patterns suggests another plausible mechanism for sea ice reemergence.

  15. The Arctic Sea ice in the CMIP3 climate model ensemble – variability and anthropogenic change

    Directory of Open Access Journals (Sweden)

    L. K. Behrens

    2012-12-01

    Full Text Available The strongest manifestation of global warming is observed in the Arctic. The warming in the Arctic during the recent decades is about twice as strong as in the global average and has been accompanied by a summer sea ice decline that is very likely unprecedented during the last millennium. Here, Arctic sea ice variability is analyzed in the ensemble of CMIP3 models. Complementary to several previous studies, we focus on regional aspects, in particular on the Barents Sea. We also investigate the changes in the seasonal cycle and interannual variability. In all regions, the models predict a reduction in sea ice area and sea ice volume during 1900–2100. Toward the end of the 21st century, the models simulate higher sea ice area variability in September than in March, whereas the variability in the preindustrial control runs is higher in March. Furthermore, the amplitude and phase of the sea ice seasonal cycle change in response to enhanced greenhouse warming. The amplitude of the sea ice area seasonal cycle increases due to the very strong sea ice area decline in September. The seasonal cycle amplitude of the sea ice volume decreases due to the stronger reduction of sea ice volume in March.

    Multi-model mean estimates for the late 20th century are comparable with observational data only for the entire Arctic and the Central Arctic. In the Barents Sea, differences between the multi-model mean and the observational data are more pronounced. Regional sea ice sensitivity to Northern Hemisphere average surface warming has been investigated.

  16. Ice Complex permafrost of MIS5 age in the Dmitry Laptev Strait coastal region (East Siberian Arctic)

    Science.gov (United States)

    Wetterich, Sebastian; Tumskoy, Vladimir; Rudaya, Natalia; Kuznetsov, Vladislav; Maksimov, Fedor; Opel, Thomas; Meyer, Hanno; Andreev, Andrei A.; Schirrmeister, Lutz

    2016-09-01

    Ice Complex deposits (locally known as the Buchchagy Ice Complex) are exposed at both coasts of the East Siberian Dmitry Laptev Strait and preserved below the Yedoma Ice Complex that formed during MIS3 and MIS2 (Marine Isotope Stage) and lateglacial-Holocene thermokarst deposits (MIS1). Radioisotope disequilibria (230Th/U) of peaty horizons date the Buchchagy Ice Complex deposition to 126 + 16/-13 kyr and 117 + 19/-14 kyr until 98 ± 5 kyr and 89 ± 5 kyr. The deposit is characterised by poorly-sorted medium-to-coarse silts with cryogenic structures of horizontal ice bands, lens-like, and lens-like reticulated segregation ice. Two peaty horizons within the Buchchagy Ice Complex and syngenetic ice wedges (2-4 m wide, up to 10 m high) are striking. The isotopic composition (δ18O, δD) of Buchchagy ice-wedge ice indicates winter conditions colder than during the MIS3 interstadial and warmer than during MIS2 stadial, and similar atmospheric winter moisture sources as during the MIS2 stadial. Buchchagy Ice Complex pollen spectra reveal tundra-steppe vegetation and harsher summer conditions than during the MIS3 interstadial and rather similar vegetation as during the MIS2 stadial. Short-term climatic variability during MIS5 is reflected in the record. Even though the regional chronostratigraphic relationship of the Buchchagy Ice Complex to the Last Interglacial remains unclear because numerical dating is widely lacking, the present study indicates permafrost (Ice Complex) formation during MIS5 sensu lato, and its preservation afterwards. Palaeoenvironmental insights into past climate and the periglacial landscape dynamics of arctic lowlands in eastern Siberia are deduced from the record.

  17. Impact of prescribed Arctic sea ice thickness in simulations of the present and future climate

    Energy Technology Data Exchange (ETDEWEB)

    Krinner, Gerhard [Alfred Wegener Institute for Polar and Marine Research, Potsdam (Germany); INSU-CNRS and UJF Grenoble, Laboratoire de Glaciologie et Geophysique de l' Environnement (LGGE), 54 rue Moliere, BP 96, Saint Martin d' Heres Cedex (France); Rinke, Annette; Dethloff, Klaus [Alfred Wegener Institute for Polar and Marine Research, Potsdam (Germany); Gorodetskaya, Irina V. [INSU-CNRS and UJF Grenoble, Laboratoire de Glaciologie et Geophysique de l' Environnement (LGGE), 54 rue Moliere, BP 96, Saint Martin d' Heres Cedex (France)

    2010-09-15

    This paper describes atmospheric general circulation model climate change experiments in which the Arctic sea-ice thickness is either fixed to 3 m or somewhat more realistically parameterized in order to take into account essentially the spatial variability of Arctic sea-ice thickness, which is, to a first approximation, a function of ice type (perennial or seasonal). It is shown that, both at present and at the end of the twenty-first century (under the SRES-A1B greenhouse gas scenario), the impact of a variable sea-ice thickness compared to a uniform value is essentially limited to the cold seasons and the lower troposphere. However, because first-year ice is scarce in the Central Arctic today, but not under SRES-A1B conditions at the end of the twenty-first century, and because the impact of a sea-ice thickness reduction can be masked by changes of the open water fraction, the spatial and temporal patterns of the effect of sea-ice thinning on the atmosphere differ between the two periods considered. As a consequence, not only the climate simulated at a given period, but also the simulated Arctic climate change over the twenty-first century is affected by the way sea-ice thickness is prescribed. (orig.)

  18. Sea ice concentration and sea ice drift for the Arctic summer using C- and L-band SAR

    Science.gov (United States)

    Johansson, Malin; Berg, Anders; Eriksson, Leif

    2014-05-01

    The decreasing amount of sea ice and changes from multi-year ice to first year ice within the Arctic Ocean opens up for increased maritime activities. These activities include transportation, fishing and tourism. One of the major threats for the shipping is the presence of sea ice. Should an oil spill occur, the search and rescue is heavily dependent on constant updates of sea ice movements, both to enable a safer working environment and to potentially prevent the oil from reaching the sea ice. It is therefore necessary to have accurate and updated sea ice charts for the Arctic Ocean during the entire year. During the melt season that ice is subject to melting conditions making satellite observations of sea ice more difficult. This period coincides with the peak in marine shipping activities and therefore requires highly accurate sea ice concentration estimates. Synthetic Aperture Radar (SAR) are not hindered by clouds and do not require daylight. The continuous record and high temporal resolution makes C-band data preferable as input data for operational sea ice mapping. However, with C-band SAR it is sometimes difficult to distinguish between a wet sea ice surface and surrounding open water. L-band SAR has a larger penetration depth and has been shown to be less sensitive to less sensitive than C-band to the melt season. Inclusion of L-band data into sea chart estimates during the melt season in particular could therefore improve sea ice monitoring. We compare sea ice concentration melt season observations using Advanced Land Observing Satellite (ALOS) L-band images with Envisat ASAR C-band images. We evaluate if L-band images can be used to improve separation of wet surface ice from open water and compare with results for C-band.

  19. Near-real-time Arctic sea ice thickness and volume from CryoSat-2

    Science.gov (United States)

    Tilling, Rachel L.; Ridout, Andy; Shepherd, Andrew

    2016-09-01

    Timely observations of sea ice thickness help us to understand the Arctic climate, and have the potential to support seasonal forecasts and operational activities in the polar regions. Although it is possible to calculate Arctic sea ice thickness using measurements acquired by CryoSat-2, the latency of the final release data set is typically 1 month due to the time required to determine precise satellite orbits. We use a new fast-delivery CryoSat-2 data set based on preliminary orbits to compute Arctic sea ice thickness in near real time (NRT), and analyse this data for one sea ice growth season from October 2014 to April 2015. We show that this NRT sea-ice-thickness product is of comparable accuracy to that produced using the final release CryoSat-2 data, with a mean thickness difference of 0.9 cm, demonstrating that the satellite orbit is not a critical factor in determining sea ice freeboard. In addition, the CryoSat-2 fast-delivery product also provides measurements of Arctic sea ice thickness within 3 days of acquisition by the satellite, and a measurement is delivered, on average, within 14, 7 and 6 km of each location in the Arctic every 2, 14 and 28 days respectively. The CryoSat-2 NRT sea-ice-thickness data set provides an additional constraint for short-term and seasonal predictions of changes in the Arctic ice cover and could support industries such as tourism and transport through assimilation in operational models.

  20. Future increases in Arctic precipitation linked to local evaporation and sea ice retreat

    Science.gov (United States)

    Bintanja, Richard; Selten, Frank

    2016-04-01

    Projected end-of-the-21st-century precipitation trends show an increase of over 50% in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate model output in standardised forcing simulations to quantify 21st-century trends in the Arctic moisture budget, revealing that the projected increase in Arctic precipitation (peaking in late fall and winter) is in fact due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree to enhanced moisture inflow from lower latitudes (maximum in late summer/fall). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea ice decline. As a result, the Arctic mean precipitation sensitivity (4.5% increase per degree temperature warming) is much larger than the global value (1.6 - 1.9%/K). The associated seasonally varying increase in Arctic precipitation will reinforce river discharge, enhance ice sheet mass balance and thereby affect global sea level, and may even impact global climate through Arctic Ocean freshening and subsequent modulations of the Atlantic Meridional Overturning Circulation. Bintanja, R. and F.M. Selten, 2014: Future increases in Arctic precipitation linked to local evaporation and sea ice retreat. Nature, 509, 479-482, doi:10.1038/nature13259.

  1. Arctic energy budget in relation to sea-ice variability on monthly to annual time scales

    Science.gov (United States)

    Krikken, Folmer; Hazeleger, Wilco

    2015-04-01

    The strong decrease in Arctic sea-ice in recent years has triggered a strong interest in Arctic sea-ice predictions on seasonal to decadal time scales. Hence, it is key to understand physical processes that provide enhanced predictability beyond persistence of sea ice anomalies. The authors report on an analysis of natural variability of Arctic sea-ice from an energy budget perspective, using 15 CMIP5 climate models, and comparing these results to atmospheric and oceanic reanalyses data. We quantify the persistence of sea ice anomalies and the cross-correlation with the surface and top energy budget components. The Arctic energy balance components primarily indicate the important role of the seasonal sea-ice albedo feedback, in which sea-ice anomalies in the melt season reemerge in the growth season. This is a robust anomaly reemergence mechanism among all 15 climate models. The role of ocean lies mainly in storing heat content anomalies in spring, and releasing them in autumn. Ocean heat flux variations only play a minor role. The role of clouds is further investigated. We demonstrate that there is no direct atmospheric response of clouds to spring sea-ice anomalies, but a delayed response is evident in autumn. Hence, there is no cloud-ice feedback in late spring and summer, but there is a cloud-ice feedback in autumn, which strengthens the ice-albedo feedback. Anomalies in insolation are positively correlated with sea-ice variability. This is primarily a result of reduced multiple-reflection of insolation due to an albedo decrease. This effect counteracts the sea-ice albedo effect up to 50%. ERA-Interim and ORAS4 confirm the main findings from the climate models.

  2. Fracture of summer perennial sea ice by ocean swell as a result of Arctic storms

    Science.gov (United States)

    Asplin, Matthew G.; Galley, Ryan; Barber, David G.; Prinsenberg, Simon

    2012-06-01

    The Arctic summer minimum sea ice extent has experienced a decreasing trend since 1979, with an extreme minimum extent of 4.27 × 106 km2 in September 2007, and a similar minimum in 2011. Large expanses of open water in the Siberian, Laptev, Chukchi, and Beaufort Seas result from declining summer sea ice cover, and consequently introduce long fetch within the Arctic Basin. Strong winds from migratory cyclones coupled with increasing fetch generate large waves which can propagate into the pack ice and break it up. On 06 September 2009, we observed the intrusion of large swells into the multiyear pack ice approximately 250 km from the ice edge. These large swells induced nearly instantaneous widespread fracturing of the multiyear pack ice, reducing the large, (>1 km diameter) parent ice floes to small (100-150 m diameter) floes. This process increased the total ice floe perimeter exposed to the open ocean, allowing for more efficient distribution of energy from ocean heat fluxes, and incoming radiation into the floes, thereby enhancing lateral melting. This process of sea ice decay is therefore presented as a potential positive feedback process that will accelerate the loss of Arctic sea ice.

  3. New wave systems in the "ice-free" future of the Arctic Ocean

    Science.gov (United States)

    Dobrynin, Mikhail; Murawski, Jens; Pohlmann, Thomas

    2016-04-01

    Near "ice-free" future of the Arctic Ocean offers new possibilities for maritime activities. Retreat of the sea ice projected in the climate change scenarios in the coming decades will open new ship routes, which potentially can be much more efficient compared to the present days. Nevertheless, it is currently unknown what kind of wave systems will develop under new ice conditions. We investigate the near future of the Arctic wave climate using new projections of wind and ice conditions from the CMIP5 set of experiments. We use the output (wind and ice data) of an Earth system model (EC-Earth) to force a high-resolution Arctic setup of the wave model WAM. The grid of the WAM was rotated ensuring a free propagation of waves over the North Pole. Model results from the historical (spanning the years 1850-2010) and future projections (for the period of 2010-2100) of Earth's climate will be presented. We investigate the changes in the wave systems of the Arctic Ocean under future sea ice conditions. We show that the region will develop new patterns in wave regimes including the generation of the Arctic swell and the new surfing zones along the coastal line.

  4. Object-based Image Classification of Arctic Sea Ice and Melt Ponds through Aerial Photos

    Science.gov (United States)

    Miao, X.; Xie, H.; Li, Z.; Lei, R.

    2013-12-01

    The last six years have marked the lowest Arctic summer sea ice extents in the modern era, with a new record summer minimum (3.4 million km2) set on 13 September 2012. It has been predicted that the Arctic could be free of summer ice within the next 25-30. The loss of Arctic summer ice could have serious consequences, such as higher water temperature due to the positive feedback of albedo, more powerful and frequent storms, rising sea levels, diminished habitats for polar animals, and more pollution due to fossil fuel exploitation and/ or increased traffic through the Northwest/ Northeast Passage. In these processes, melt ponds play an important role in Earth's radiation balance since they strongly absorb solar radiation rather than reflecting it as snow and ice do. Therefore, it is necessary to develop the ability of predicting the sea ice/ melt pond extents and space-time evolution, which is pivotal to prepare for the variation and uncertainty of the future environment, political, economic, and military needs. A lot of efforts have been put into Arctic sea ice modeling to simulate sea ice processes. However, these sea ice models were initiated and developed based on limited field surveys, aircraft or satellite image data. Therefore, it is necessary to collect high resolution sea ice aerial photo in a systematic way to tune up, validate, and improve models. Currently there are many sea ice aerial photos available, such as Chinese Arctic Exploration (CHINARE 2008, 2010, 2012), SHEBA 1998 and HOTRAX 2005. However, manually delineating of sea ice and melt pond from these images is time-consuming and labor-intensive. In this study, we use the object-based remote sensing classification scheme to extract sea ice and melt ponds efficiently from 1,727 aerial photos taken during the CHINARE 2010. The algorithm includes three major steps as follows. (1) Image segmentation groups the neighboring pixels into objects according to the similarity of spectral and texture

  5. Ku-band radar penetration into snow cover Arctic sea ice using airborne data

    OpenAIRE

    Willatt, R.; Laxon, S.; Giles, K.; R. Cullen; Haas, C.; V. Helm

    2011-01-01

    Satellite radar altimetry provides data to monitor winter Arctic sea-ice thickness variability on interannual, basin-wide scales. When using this technique an assumption is made that the peak of the radar return originates from the snow/ice interface. This has been shown to be true in the laboratory for cold, dry snow as is the case on Arctic sea ice during winter. However, this assumption has not been tested in the field. We use data from an airborne normal-incidence Ku-band radar altimeter ...

  6. Determination of Changes in the State of the Arctic Ice Pack Using the NPS Pan-Arctic Coupled Ice-Ocean Model

    Science.gov (United States)

    2006-03-01

    54 Francis, Jennifer A., Elias Hunter, Jeffrey R. Key and Xuanji Wang, “Clues To Variability in Arctic Minimum Sea Ice Extent,” Geophysical...3975, 15 December 2000. Warren, Stephen G., Ignatius G. Rigor, Norbert Untersteiner, Vladimir F. Radionov, Nikolay N. Bryazgin, Yevgeniy I

  7. Detecting Arctic snow and ice cover with FY-1D global data

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chinese meteorological satellite FY-1D can obtain global data from four spectral channels which include visible channel (0.58-0.68 μm) and infrared channels (0.84-0.89 μm, 10.3-11.3 μm, 11.5-12.5 μm). 2366 snow and ice samples, 2024 cloud samples, 1602 land samples and 1648 water samples were selected randomly from Arctic imageries. Land and water can be detected by spectral features. Snow-ice and cloud can be classified by textural features. The classifier is Bayes classifier. By synthesizing five d ays classifying result of Arctic snow and ice cover area, complete Arctic snow and ice cover area can be obtained. The result agrees with NOAA/NESDIS IMS products up to 70%.

  8. Sea ice phenology and timing of primary production pulses in the Arctic Ocean.

    Science.gov (United States)

    Ji, Rubao; Jin, Meibing; Varpe, Øystein

    2013-03-01

    Arctic organisms are adapted to the strong seasonality of environmental forcing. A small timing mismatch between biological processes and the environment could potentially have significant consequences for the entire food web. Climate warming causes shrinking ice coverage and earlier ice retreat in the Arctic, which is likely to change the timing of primary production. In this study, we test predictions on the interactions among sea ice phenology and production timing of ice algae and pelagic phytoplankton. We do so using the following (1) a synthesis of available satellite observation data; and (2) the application of a coupled ice-ocean ecosystem model. The data and model results suggest that, over a large portion of the Arctic marginal seas, the timing variability in ice retreat at a specific location has a strong impact on the timing variability in pelagic phytoplankton peaks, but weak or no impact on the timing of ice-algae peaks in those regions. The model predicts latitudinal and regional differences in the timing of ice algae biomass peak (varying from April to May) and the time lags between ice algae and pelagic phytoplankton peaks (varying from 45 to 90 days). The correlation between the time lag and ice retreat is significant in areas where ice retreat has no significant impact on ice-algae peak timing, suggesting that changes in pelagic phytoplankton peak timing control the variability in time lags. Phenological variability in primary production is likely to have consequences for higher trophic levels, particularly for the zooplankton grazers, whose main food source is composed of the dually pulsed algae production of the Arctic.

  9. Assessment of Arctic and Antarctic sea ice predictability in CMIP5 decadal hindcasts

    Science.gov (United States)

    Yang, Chao-Yuan; Liu, Jiping; Hu, Yongyun; Horton, Radley M.; Chen, Liqi; Cheng, Xiao

    2016-10-01

    This paper examines the ability of coupled global climate models to predict decadal variability of Arctic and Antarctic sea ice. We analyze decadal hindcasts/predictions of 11 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Decadal hindcasts exhibit a large multi-model spread in the simulated sea ice extent, with some models deviating significantly from the observations as the predicted ice extent quickly drifts away from the initial constraint. The anomaly correlation analysis between the decadal hindcast and observed sea ice suggests that in the Arctic, for most models, the areas showing significant predictive skill become broader associated with increasing lead times. This area expansion is largely because nearly all the models are capable of predicting the observed decreasing Arctic sea ice cover. Sea ice extent in the North Pacific has better predictive skill than that in the North Atlantic (particularly at a lead time of 3-7 years), but there is a re-emerging predictive skill in the North Atlantic at a lead time of 6-8 years. In contrast to the Arctic, Antarctic sea ice decadal hindcasts do not show broad predictive skill at any timescales, and there is no obvious improvement linking the areal extent of significant predictive skill to lead time increase. This might be because nearly all the models predict a retreating Antarctic sea ice cover, opposite to the observations. For the Arctic, the predictive skill of the multi-model ensemble mean outperforms most models and the persistence prediction at longer timescales, which is not the case for the Antarctic. Overall, for the Arctic, initialized decadal hindcasts show improved predictive skill compared to uninitialized simulations, although this improvement is not present in the Antarctic.

  10. [The arctic sea ice refractive index retrieval based on satellite AMSR-E observations].

    Science.gov (United States)

    Chen, Han-Yue; Bi, Hai-Bo; Niu, Zheng

    2012-11-01

    The refractive index of sea ice in the polar region is an important geophysical parameter. It is needed as a vital input for some numerical climate models and is helpful to classifying sea ice types. In the present study, according to Hong Approximation (HA), we retrieved the arctic sea ice refractive index at 6.9, 10.7, 23, 37, and 89 GHz in different arctic climatological conditions. The refractive indices of wintertime first year (FY) sea ice and summertime ice were derived with average values of 1.78 - 1.75 and 1.724 - 1.70 at different frequencies respectively, which are consistent with previous studies. However, for multiyear (MY) ice, the results indicated relatively large bias between modeled results since 10.7 GHz. At a higher frequency, there is larger MY ice refractive index difference. This bias is mainly attributed to the volume scattering effect on MY microwave radiation due to emergence of massive small empty cavities after the brine water in MY ice is discharged into sea. In addition, the retrieved sea ice refractive indices can be utilized to classify ice types (for example, the winter derivation at 89 GHz), to identify coastal polynyas (winter retrieval at 6.9 GHz), and to outline the areal extent of significantly melting marginal sea ice zone (MIZ) (summer result at 6.9 GHz). The investigation of this study suggests an effective tool of passive microwave remote sensing in monitoring sea ice refractive index variability.

  11. Additional Arctic observations improve weather and sea-ice forecasts for the Northern Sea Route.

    Science.gov (United States)

    Inoue, Jun; Yamazaki, Akira; Ono, Jun; Dethloff, Klaus; Maturilli, Marion; Neuber, Roland; Edwards, Patti; Yamaguchi, Hajime

    2015-01-01

    During ice-free periods, the Northern Sea Route (NSR) could be an attractive shipping route. The decline in Arctic sea-ice extent, however, could be associated with an increase in the frequency of the causes of severe weather phenomena, and high wind-driven waves and the advection of sea ice could make ship navigation along the NSR difficult. Accurate forecasts of weather and sea ice are desirable for safe navigation, but large uncertainties exist in current forecasts, partly owing to the sparse observational network over the Arctic Ocean. Here, we show that the incorporation of additional Arctic observations improves the initial analysis and enhances the skill of weather and sea-ice forecasts, the application of which has socioeconomic benefits. Comparison of 63-member ensemble atmospheric forecasts, using different initial data sets, revealed that additional Arctic radiosonde observations were useful for predicting a persistent strong wind event. The sea-ice forecast, initialised by the wind fields that included the effects of the observations, skilfully predicted rapid wind-driven sea-ice advection along the NSR.

  12. Experiment of near surface layer parameters in ice camp over Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Estimates of near surface layer parameters over (78.) N drifting ice in ice camp over the Arctic ocean are made using bulk transfer methods with the data from the experiments operated by the Chinese Arctic Scientific Expedition in August 22 September 3, 2003.The results show that the net radiation received by the snow surface is only 3.6 W/m2, among which the main part transported into atmosphere in term of sensible heat and latent heat, which account for 52% and 31% respectively,and less part being transported to deep ice in the conductive process.The bulk transfer coefficient of momentum is about 1.16 x 10-3 in the near neutral layer, which is a little smaller than that obtained over (75.)N drifting ice.However, to compare with the results observed over 75°N drifting ice over the Arctic Ocean in 1999, it can be found that the thermodynamic and momentum of interactions between sea and air are significant different with latitudes, concentration and the scale of sea ice.It is very important on considering the effect of sea-air-ice interaction over the Arctic Ocean when studying climate modeling.

  13. Predictions replaced by facts: a keystone species' behavioural responses to declining arctic sea-ice.

    Science.gov (United States)

    Hamilton, Charmain D; Lydersen, Christian; Ims, Rolf A; Kovacs, Kit M

    2015-11-01

    Since the first documentation of climate-warming induced declines in arctic sea-ice, predictions have been made regarding the expected negative consequences for endemic marine mammals. But, several decades later, little hard evidence exists regarding the responses of these animals to the ongoing environmental changes. Herein, we report the first empirical evidence of a dramatic shift in movement patterns and foraging behaviour of the arctic endemic ringed seal (Pusa hispida), before and after a major collapse in sea-ice in Svalbard, Norway. Among other changes to the ice-regime, this collapse shifted the summer position of the marginal ice zone from over the continental shelf, northward to the deep Arctic Ocean Basin. Following this change, which is thought to be a 'tipping point', subadult ringed seals swam greater distances, showed less area-restricted search behaviour, dived for longer periods, exhibited shorter surface intervals, rested less on sea-ice and did less diving directly beneath the ice during post-moulting foraging excursions. In combination, these behavioural changes suggest increased foraging effort and thus also likely increases in the energetic costs of finding food. Continued declines in sea-ice are likely to result in distributional changes, range reductions and population declines in this keystone arctic species.

  14. Sea ice decline and 21st century trans-Arctic shipping routes

    Science.gov (United States)

    Melia, N.; Haines, K.; Hawkins, E.

    2016-09-01

    The observed decline in Arctic sea ice is projected to continue, opening shorter trade routes across the Arctic Ocean, with potentially global economic implications. Here we quantify, using Coupled Model Intercomparison Project Phase 5 global climate model simulations calibrated to remove spatial biases, how projected sea ice loss might increase opportunities for Arctic transit shipping. By midcentury for standard open water vessels, the frequency of navigable periods doubles, with routes across the central Arctic becoming available. A sea ice-ship speed relationship is used to show that European routes to Asia typically become 10 days faster via the Arctic than alternatives by midcentury, and 13 days faster by late century, while North American routes become 4 days faster. Future greenhouse gas emissions have a larger impact by late century; the shipping season reaching 4-8 months in Representative Concentration Pathway (RCP)8.5 double that of RCP2.6, both with substantial interannual variability. Moderately, ice-strengthened vessels likely enable Arctic transits for 10-12 months by late century.

  15. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

    Science.gov (United States)

    Liljedahl, Anna K.; Boike, Julia; Daanen, Ronald P.; Fedorov, Alexander N.; Frost, Gerald V.; Grosse, Guido; Hinzman, Larry D.; Iijma, Yoshihiro; Jorgenson, Janet C.; Matveyeva, Nadya; Necsoiu, Marius; Raynolds, Martha K.; Romanovsky, Vladimir E.; Schulla, Jörg; Tape, Ken D.; Walker, Donald A.; Wilson, Cathy J.; Yabuki, Hironori; Zona, Donatella

    2016-04-01

    Ice wedges are common features of the subsurface in permafrost regions. They develop by repeated frost cracking and ice vein growth over hundreds to thousands of years. Ice-wedge formation causes the archetypal polygonal patterns seen in tundra across the Arctic landscape. Here we use field and remote sensing observations to document polygon succession due to ice-wedge degradation and trough development in ten Arctic localities over sub-decadal timescales. Initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds. Continued ice-wedge melting leads to increased trough connectivity and an overall draining of the landscape. We find that melting at the tops of ice wedges over recent decades and subsequent decimetre-scale ground subsidence is a widespread Arctic phenomenon. Although permafrost temperatures have been increasing gradually, we find that ice-wedge degradation is occurring on sub-decadal timescales. Our hydrological model simulations show that advanced ice-wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff, in particular due to changes in snow distribution as troughs form. We predict that ice-wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions.

  16. Orbital-Scale Cyclostratigraphy and Ice Volume Fluctuations from Arctic Ocean Sediments

    Science.gov (United States)

    Cronin, T. M.; Marzen, R.; DeNinno, L. H.

    2014-12-01

    Deep-sea foraminiferal oxygen isotope curves (δ18Of) are excellent paleoclimate records but are limited as proxies of global ice volume history during orbital glacial-interglacial cycles (GIC) due to the influence of deep-sea bottom water temperature, regional hydrography, ocean circulation and other factors affecting δ18Of. A more direct source of northern hemisphere [NH] ice history comes from central Arctic Ocean (CAO) submarine ridges (Northwind, Mendeleev, Lomonosov) where, at orbital timescales, sedimentation is controlled by the growth and decay of ice sheets, ice shelves, and sea ice. Calcareous microfossil density in CAO sediments is one of many proxies, such as manganese concentrations, grain size, bulk density, color, mineral content, organic geochemistry, and foraminiferal δ18O, that reveal GIC changes in ice cover, biological productivity, and primary and post-depositional sediment processes. In order to better understand NH ice history, we constructed 600-kyr-long stacked records of Arctic foraminiferal and ostracode density (AFD, AOD) from 19 CAO sediment cores following stacking and astronomical tuning procedures used for deep-sea δ18Of curves. Results show discrepancies between the Arctic AFD and AOD curves, the LR04 δ18Of stack (Lisiecki and Raymo 2005, Paleoceanography), the Red Sea and Mediterranean δ18Of sea level curves (Rohling et al. 2014 Nature), and modeled Antarctic Ice Sheet volume, suggesting asynchronous polar ice sheet behavior in the two hemispheres, notably during MIS 3, 5a, 5c, 7d, and 11.

  17. Visible and Thermal Imaging of Sea Ice and Open Water from Coast Guard Arctic Domain Awareness Flights

    Science.gov (United States)

    2014-09-30

    seasonal evolution of the ice cover. APPROACH The Coast Guard Arctic Domain Awareness (ADA) flights based out of Kodiak Alaska offer a tremendous...and Thermal Imaging of Sea Ice and Open Water from Coast Guard Arctic Domain Awareness Flights 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...temperature, melt pond temperature, percentage ice coverage, and ice flow and melt pond size 3 distributions. We are also collaborating within APL

  18. The Multi-Sectorial Impact Of Arctic Sea Ice Loss by Jeremy Wilkinson (on behalf of the ICE-ARC Team)

    Science.gov (United States)

    Wilkinson, J.

    2015-12-01

    One of the most visible aspects of climate change is the dramatic loss of Arctic sea ice; both sea ice extent and thickness. The striking loss of sea-ice in recent summers reflects profound changes in the Arctic system. However these climate driven changes in sea ice are not the only pressures on the region as the increase in the demand for natural resources are providing opportunities for investment, with estimates of $100bn or more coming in to the Arctic region over the next decade. Sea ice loss is one of the drivers behind this investment. However the environmental, socio-economic, and geopolitical consequences associated with sea ice loss bring opportunities and possibilities, but also far-reaching change amidst the potential conflicts and risks for human activities right across the Arctic and the globe. To better understand the impact of sea ice loss a multi-sectorial approach is needed. This innovative multi-sector approach to sea ice loss has gained traction over recent years as it transcends disciplinary boundaries, advances knowledge of Arctic change within a regional and global context, has a sharp eye to policy-relevance, and builds strong partnerships with northern communities. Ice Climate and Economics: Arctic Research on Change (ICE-ARC) is one of these programmes. ICE-ARC involves 23 institutes from 11 European Union and Russia. We present initial results from this exciting, multi-sectorial research programme.

  19. Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard

    Directory of Open Access Journals (Sweden)

    Vladimir V. Ivanov

    2012-01-01

    Full Text Available We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW boundary releases substantial heat upwards that eventually reaches the under-ice water layer, thinning the ice cover. We examine spatial and temporal variation of ice concentration against time series of wind, air temperature, and AW temperature. Analysis of 1979–2011 ice properties revealed a general tendency of decreasing ice concentration that commenced after the mid-1990s. AW temperature time series in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. Ice thins due to increased sensible heat flux from AW; ice erosion from below allows wind and local currents to more effectively break ice. The winter spatial pattern of sea ice concentration is collocated with patterns of surface heat flux anomalies. Winter minimum sea ice thickness occurs in the ice pack interior above the AW path, clearly indicating AW influence on ice thickness. Our study indicates that in the AW inflow region heat flux from the ocean reduces the ice thickness.

  20. Interactions of arctic clouds, radiation, and sea ice in present-day and future climates

    Science.gov (United States)

    Burt, Melissa Ann

    The Arctic climate system involves complex interactions among the atmosphere, land surface, and the sea-ice-covered Arctic Ocean. Observed changes in the Arctic have emerged and projected climate trends are of significant concern. Surface warming over the last few decades is nearly double that of the entire Earth. Reduced sea-ice extent and volume, changes to ecosystems, and melting permafrost are some examples of noticeable changes in the region. This work is aimed at improving our understanding of how Arctic clouds interact with, and influence, the surface budget, how clouds influence the distribution of sea ice, and the role of downwelling longwave radiation (DLR) in climate change. In the first half of this study, we explore the roles of sea-ice thickness and downwelling longwave radiation in Arctic amplification. As the Arctic sea ice thins and ultimately disappears in a warming climate, its insulating power decreases. This causes the surface air temperature to approach the temperature of the relatively warm ocean water below the ice. The resulting increases in air temperature, water vapor and cloudiness lead to an increase in the surface downwelling longwave radiation, which enables a further thinning of the ice. This positive ice-insulation feedback operates mainly in the autumn and winter. A climate-change simulation with the Community Earth System Model shows that, averaged over the year, the increase in Arctic DLR is three times stronger than the increase in Arctic absorbed solar radiation at the surface. The warming of the surface air over the Arctic Ocean during fall and winter creates a strong thermal contrast with the colder surrounding continents. Sea-level pressure falls over the Arctic Ocean and the high-latitude circulation reorganizes into a shallow "winter monsoon." The resulting increase in surface wind speed promotes stronger surface evaporation and higher humidity over portions of the Arctic Ocean, thus reinforcing the ice-insulation feedback

  1. Sea-Ice Wintertime Lead Frequencies and Regional Characteristics in the Arctic, 2003–2015

    Directory of Open Access Journals (Sweden)

    Sascha Willmes

    2015-12-01

    Full Text Available The presence of sea-ice leads represents a key feature of the Arctic sea ice cover. Leads promote the flux of sensible and latent heat from the ocean to the cold winter atmosphere and are thereby crucial for air-sea-ice-ocean interactions. We here apply a binary segmentation procedure to identify leads from MODIS thermal infrared imagery on a daily time scale. The method separates identified leads into two uncertainty categories, with the high uncertainty being attributed to artifacts that arise from warm signatures of unrecognized clouds. Based on the obtained lead detections, we compute quasi-daily pan-Arctic lead maps for the months of January to April, 2003–2015. Our results highlight the marginal ice zone in the Fram Strait and Barents Sea as the primary region for lead activity. The spatial distribution of the average pan-Arctic lead frequencies reveals, moreover, distinct patterns of predominant fracture zones in the Beaufort Sea and along the shelf-breaks, mainly in the Siberian sector of the Arctic Ocean as well as the well-known polynya and fast-ice locations. Additionally, a substantial inter-annual variability of lead occurrences in the Arctic is indicated.

  2. Mitigation implications of an ice-free summer in the Arctic Ocean

    Science.gov (United States)

    González-Eguino, Mikel; Neumann, Marc B.; Arto, Iñaki; Capellán-Perez, Iñigo; Faria, Sérgio H.

    2017-01-01

    The rapid loss of sea ice in the Arctic is one of the most striking manifestations of climate change. As sea ice melts, more open water is exposed to solar radiation, absorbing heat and generating a sea-ice-albedo feedback that reinforces Arctic warming. Recent studies stress the significance of this feedback mechanism and suggest that ice-free summer conditions in the Arctic Ocean may occur faster than previously expected, even under low-emissions pathways. Here we use an integrated assessment model to explore the implications of a potentially rapid sea-ice-loss process. We consider a scenario leading to a full month free of sea ice in September 2050, followed by three potential trajectories afterward: partial recovery, stabilization, and continued loss of sea ice. We analyze how these scenarios affect the efforts to keep global temperature increase below 2°C. Our results show that sea-ice melting in the Arctic requires more stringent mitigation efforts globally. We find that global CO2 emissions would need to reach zero levels 5-15 years earlier and that the carbon budget would need to be reduced by 20%-51% to offset this additional source of warming. The extra mitigation effort would imply an 18%-59% higher mitigation cost to society. Our results also show that to achieve the 1.5°C target in the presence of ice-free summers negative emissions would be needed. This study highlights the need for a better understanding of how the rapid changes observed in the Arctic may impact our society.

  3. On Wave-Ice Interaction in the Arctic Marginal Ice Zone: Dispersion, Attenuation, and Ice Response

    Science.gov (United States)

    2016-06-01

    for forecasting waves in the Arctic and thus many simplifications are necessary. An anecdote, related by Zubov via an earlier publication by...Naval Research Laboratory Stennis Space Center, MS 39529-5004 NRL/MR/7320--16-9676 Approved for public release; distribution is unlimited. On Wave...To) Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Public reporting burden for this collection of information is estimated to average 1

  4. Relationships linking primary production, sea ice melting, and biogenic aerosol in the Arctic

    Science.gov (United States)

    Becagli, S.; Lazzara, L.; Marchese, C.; Dayan, U.; Ascanius, S. E.; Cacciani, M.; Caiazzo, L.; Di Biagio, C.; Di Iorio, T.; di Sarra, A.; Eriksen, P.; Fani, F.; Giardi, F.; Meloni, D.; Muscari, G.; Pace, G.; Severi, M.; Traversi, R.; Udisti, R.

    2016-07-01

    diatoms, which are prolific DMS producers, whereas in the Greenland Sea the DMS peak is related to an offshore pelagic bloom where low-DMS producer species are present. The sea ice dynamic plays a key role in determining MSA concentration in the Arctic, and a good correlation between MSA and SIM (slope = 39 ng m-3 of MSA/106 km2 SIM) and between MSA and IF-MIZ (slope = 56 ng m-3 of MSA/106 km2 IF-MIZ) is found for the cases attributable to bloomings of diatoms in the MIZ. Such relationships are calculated by combining the data sets from the two sites and suggest that PP is related to sea ice melting and to the extension of marginal sea ice areas, and that these factors are the main drivers for MSA concentrations at the considered Arctic sites.

  5. In situ expression of eukaryotic ice-binding proteins in microbial communities of Arctic and Antarctic sea ice

    Science.gov (United States)

    Uhlig, Christiane; Kilpert, Fabian; Frickenhaus, Stephan; Kegel, Jessica U; Krell, Andreas; Mock, Thomas; Valentin, Klaus; Beszteri, Bánk

    2015-01-01

    Ice-binding proteins (IBPs) have been isolated from various sea-ice organisms. Their characterisation points to a crucial role in protecting the organisms in sub-zero environments. However, their in situ abundance and diversity in natural sea-ice microbial communities is largely unknown. In this study, we analysed the expression and phylogenetic diversity of eukaryotic IBP transcripts from microbial communities of Arctic and Antarctic sea ice. IBP transcripts were found in abundances similar to those of proteins involved in core cellular processes such as photosynthesis. Eighty-nine percent of the IBP transcripts grouped with known IBP sequences from diatoms, haptophytes and crustaceans, but the majority represented novel sequences not previously characterized in cultured organisms. The observed high eukaryotic IBP expression in natural eukaryotic sea ice communities underlines the essential role of IBPs for survival of many microorganisms in communities living under the extreme conditions of polar sea ice. PMID:25885562

  6. Frost flowers on young Arctic sea ice: The climatic, chemical, and microbial significance of an emerging ice type

    DEFF Research Database (Denmark)

    Barber, D.; Ehn, J.; Pucko, M.

    2014-01-01

    Ongoing changes in Arctic sea ice are increasing the spatial and temporal range of young sea ice types over which frost flowers can occur, yet the significance of frost flowers to ocean-sea ice-atmosphere exchange processes remains poorly understood. Frost flowers form when moisture from seawater...... formed. The new ice and frost flowers dramatically changed the radiative and thermal environment. The frost flowers were about 5°C colder than the brine surface, with an approximately linear temperature gradient from their base to their upper tips. Salinity and δ18O values indicated that frost flowers...... of CO2 at the brine-wetted sea ice surface, in line with expectations from the brine chemistry. Bacteria concentrations generally increased with salinity in frost flowers and the surface slush layer. Bacterial densities and taxa indicated that a selective process occurred at the ice surface...

  7. Ice core from Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), dated with a Nye model modified for a growing glacier

    Science.gov (United States)

    Fritzsche, Diedrich; Opel, Thomas; Meyer, Hanno

    2010-05-01

    From 1999 to 2001 a 724 m deep ice core has been drilled from surface to bedrock close to summit of the Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), within a joint German-Russian project. The analysis of stable water isotopes and major ion concentration in high resolution were used for reconstruction of past climate and environmental changes. The upper 304 m of the core were dated by counting annual stable isotope cycles considering radioactive (1986, 1963) and volcanic events (1956, 1912, 1783, 1259) as reference horizons. The resulting depth-age relationship and the corresponding annual-layer thickness imply that the ice cap was not in dynamic steady state but had been growing until recent times. That does not comply with requirements of a standard Nye or Dansgaard-Johnson flow model approach. To take into account the peculiarities of Akademii Nauk ice cap a Nye model was modified by adding a growing term according to the found relationship between annual layer thickness and depth. Using the volcanoes identified an average increase of altitude of about 0.08 m w.e. per year was calculated since AD 1259. The model enables us to reconstruct the altitude changes of the ice cap with time and to consider an altitude effect to correct the stable isotope values and to explain decreasing sea-salt ion data. Using the suggested model annual layer thickness can be decompressed to accumulation rates at the altitude where the precipitation was originally deposited. The model can also be used for dating deeper parts of ice core where volcanoes are not identified up to now. Applying this model, the ice core has an age of about 2 500 years, much less than claimed for an older core from Akademii Nauk ice cap. Consequently, the ice cap is much younger and only of Late Holocene age, as also assumed for most Arctic ice caps and glaciers outside Greenland. However, the lowest part of Akademii Nauk ice cap is probably a remnant of an older ice cap stage.

  8. Monitoring Arctic sea ice phenology change using hypertemporal remotely sensed data: 1989-2010

    Science.gov (United States)

    Tan, Wenxia; LeDrew, Ellsworth

    2016-07-01

    Arctic sea ice has undergone a significant decline in recent years. Previous studies have demonstrated that the annual sea ice cycle has experienced earlier melt and later freeze up, leading to a significant reduction in minimum sea ice extents and the lengthening of the melting season. The Arctic is being transformed into a regime of widespread seasonal ice with a large loss of old and thick multiyear ice in recent years. However, the sea ice change exhibits considerable interannual and regional variability at different spatial and temporal scales. In this study, we present a new method for hypertemporal sea ice data change detection based on the annual sea ice concentration (SIC) profile for the melt months of each year. A decision tree-based classification is adopted to group pixels with similar annual SIC profiles, and a phenology map of each year is generated for visualization. The phenoregion map visualizes the spatial and temporal configurations of ice melt process for a year. The change detection objective is achieved by comparing the phenoregion number of the same pixel in different years. The algorithm further leads to interpretation of anomalies to obtain change maps at the pixel level. Compared to previous sea ice studies that mainly focused on a particular spatial region and commonly use time period averages, the proposed pixel-based approach has the potential to map sea ice data change both temporally and spatially.

  9. Distribution of algal aggregates under summer sea ice in the Central Arctic.

    Science.gov (United States)

    Katlein, Christian; Fernández-Méndez, Mar; Wenzhöfer, Frank; Nicolaus, Marcel

    The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess. Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling. However, the frequency and distribution of their occurrence is not well quantified. During the IceArc expedition (ARK-27/3) of RV Polarstern in late summer 2012, we observed different types of algal aggregates floating underneath various ice types in the Central Arctic basins. We investigated the spatial distribution of ice algal aggregates and quantified their biomass, using under-ice image surveys obtained by an upward-looking camera on a remotely operated vehicle. On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice. On the scale of an ice floe, the distribution of algal aggregates in late summer is mainly regulated by the topography of the ice underside, with aggregates accumulating in dome-shaped structures and at the edges of pressure ridges. The average biomass of the aggregates from our sites and season was 0.1-6.0 mg C m(-2). However, depending on the approach used, differences in orders of magnitude for biomass estimates may occur. This highlights the difficulties of upscaling observations and comparing results from surveys conducted using different methods or on different spatial scales.

  10. An analytical model for wind-driven Arctic summer sea ice drift

    Directory of Open Access Journals (Sweden)

    H.-S. Park

    2015-03-01

    Full Text Available The authors present an approximate analytical model for wind-induced sea-ice drift that includes an ice–ocean boundary layer with an Ekman spiral in the ocean velocity. This model provides an analytically tractable solution that is most applicable to the marginal ice zone, where sea-ice concentration is substantially below 100%. The model closely reproduces the ice and upper-ocean velocities observed recently by the first ice-tethered profiler equipped with a velocity sensor (ITPV. The analytical tractability of our model allows efficient calculation of the sea-ice velocity provided that the surface wind field is known and that the ocean surface geostrophic velocity is relatively weak. The model is applied to estimate intraseasonal variations in Arctic sea ice cover due to short-timescale (around 1 week intensification of the southerly winds. Utilizing 10 m surface winds from ERA-Interim reanalysis, the wind-induced sea-ice velocity and the associated changes in sea-ice concentration are calculated and compared with satellite observations. The analytical model captures the observed reduction of Arctic sea-ice concentration associated with the strengthening of southerlies on intraseasonal time scales. Further analysis indicates that the wind-induced surface Ekman flow in the ocean increases the sea-ice drift speed by 50% in the Arctic summer. It is proposed that the southerly wind-induced sea-ice drift, enhanced by the ocean's surface Ekman transport, can lead to substantial reduction in sea-ice concentration over a timescale of one week.

  11. Recent Arctic Ocean sea ice loss triggers novel fall phytoplankton blooms

    Science.gov (United States)

    Ardyna, Mathieu; Babin, Marcel; Gosselin, Michel; Devred, Emmanuel; Rainville, Luc; Tremblay, Jean-Éric

    2014-09-01

    Recent receding of the ice pack allows more sunlight to penetrate into the Arctic Ocean, enhancing productivity of a single annual phytoplankton bloom. Increasing river runoff may, however, enhance the yet pronounced upper ocean stratification and prevent any significant wind-driven vertical mixing and upward supply of nutrients, counteracting the additional light available to phytoplankton. Vertical mixing of the upper ocean is the key process that will determine the fate of marine Arctic ecosystems. Here we reveal an unexpected consequence of the Arctic ice loss: regions are now developing a second bloom in the fall, which coincides with delayed freezeup and increased exposure of the sea surface to wind stress. This implies that wind-driven vertical mixing during fall is indeed significant, at least enough to promote further primary production. The Arctic Ocean seems to be experiencing a fundamental shift from a polar to a temperate mode, which is likely to alter the marine ecosystem.

  12. Enhanced sea-ice export from the Arctic during the Younger Dryas.

    Science.gov (United States)

    Not, Christelle; Hillaire-Marcel, Claude

    2012-01-31

    The Younger Dryas cold spell of the last deglaciation and related slowing of the Atlantic meridional overturning circulation have been linked to a large array of processes, notably an influx of fresh water into the North Atlantic related to partial drainage of glacial Lake Agassiz. Here we observe a major drainage event, in marine sediment cores raised from the Lomonosov Ridge, in the central Arctic Ocean marked by a pulse in detrital dolomitic-limestones. This points to an Arctic-Canadian sediment source area with about fivefold higher Younger Dryas ice-rafting deposition rate, in comparison with the Holocene. Our findings thus support the hypothesis of a glacial drainage event in the Canadian Arctic area, at the onset of the Younger Dryas, enhancing sea-ice production and drifting through the Arctic, then export through Fram Strait, towards Atlantic meridional overturning circulation sites of the northern North Atlantic.

  13. The role of sea ice for vascular plant dispersal in the Arctic.

    Science.gov (United States)

    Alsos, Inger Greve; Ehrich, Dorothee; Seidenkrantz, Marit-Solveig; Bennike, Ole; Kirchhefer, Andreas Joachim; Geirsdottir, Aslaug

    2016-09-01

    Sea ice has been suggested to be an important factor for dispersal of vascular plants in the Arctic. To assess its role for postglacial colonization in the North Atlantic region, we compiled data on the first Late Glacial to Holocene occurrence of vascular plant species in East Greenland, Iceland, the Faroe Islands and Svalbard. For each record, we reconstructed likely past dispersal events using data on species distributions and genetics. We compared these data to sea-ice reconstructions to evaluate the potential role of sea ice in these past colonization events and finally evaluated these results using a compilation of driftwood records as an independent source of evidence that sea ice can disperse biological material. Our results show that sea ice was, in general, more prevalent along the most likely dispersal routes at times of assumed first colonization than along other possible routes. Also, driftwood is frequently dispersed in regions that have sea ice today. Thus, sea ice may act as an important dispersal agent. Melting sea ice may hamper future dispersal of Arctic plants and thereby cause more genetic differentiation. It may also limit the northwards expansion of competing boreal species, and hence favour the persistence of Arctic species.

  14. Changes in Arctic and Antarctic Sea Ice as a Microcosm of Global Climate Change

    Science.gov (United States)

    Parkinson, Claire L.

    2014-01-01

    Polar sea ice is a key element of the climate system and has now been monitored through satellite observations for over three and a half decades. The satellite observations reveal considerable information about polar ice and its changes since the late 1970s, including a prominent downward trend in Arctic sea ice coverage and a much lesser upward trend in Antarctic sea ice coverage, illustrative of the important fact that climate change entails spatial contrasts. The decreasing ice coverage in the Arctic corresponds well with contemporaneous Arctic warming and exhibits particularly large decreases in the summers of 2007 and 2012, influenced by both preconditioning and atmospheric conditions. The increasing ice coverage in the Antarctic is not as readily explained, but spatial differences in the Antarctic trends suggest a possible connection with atmospheric circulation changes that have perhaps been influenced by the Antarctic ozone hole. The changes in the polar ice covers and the issues surrounding those changes have many commonalities with broader climate changes and their surrounding issues, allowing the sea ice changes to be viewed in some important ways as a microcosm of global climate change.

  15. Sensitivity of the Arctic sea ice concentration forecasts to different atmospheric forcing:a case study

    Institute of Scientific and Technical Information of China (English)

    YANG Qinghua; LIU Jiping; ZHANG Zhanhai; SUI Cuijuan; XING Jianyong; LI Ming; LI Chunhua; ZHAO Jiechen; ZHANG Lin

    2014-01-01

    A regional Arctic configuration of the Massachusetts Institute of Technology general circulation model (MIT-gcm) is used as the coupled ice-ocean model for forecasting sea ice conditions in the Arctic Ocean at the Na-tional Marine Environmental Forecasting Center of China (NMEFC), and the numerical weather prediction from the National Center for Environmental Prediction Global Forecast System (NCEP GFS) is used as the atmospheric forcing. To improve the sea ice forecasting, a recently developed Polar Weather Research and Forecasting model (Polar WRF) model prediction is also tested as the atmospheric forcing. Their forecasting performances are evaluated with two different satellite-derived sea ice concentration products as initializa-tions: (1) the Special Sensor Microwave Imager/Sounder (SSMIS) and (2) the Advanced Microwave Scanning Radiometer for EOS (AMSR-E). Three synoptic cases, which represent the typical atmospheric circulations over the Arctic Ocean in summer 2010, are selected to carry out the Arctic sea ice numerical forecasting experiments. The evaluations suggest that the forecasts of sea ice concentrations using the Polar WRF atmo-spheric forcing show some improvements as compared with that of the NCEP GFS.

  16. Analyses of structure of planetary boundary layer in ice camp over Arctic ocean

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September, 2003. It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night. The boundary layer can be described as vertical structures of stability, instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant, which causes stronger wind shear, temperature and humidity inversion with typical wind shear of 10 m/s/100 m, intensity of temperature inversion of 8 ℃/100 m. While the larger pack ice is broken by such process, new ice free area in the high latitudes of arctic ocean. The interactions between air/ice/water are enhanced. The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region.

  17. The relation between sea ice thickness and freeboard in the Arctic

    Directory of Open Access Journals (Sweden)

    V. Alexandrov

    2010-09-01

    Full Text Available Retrieval of Arctic sea ice thickness from CryoSat-2 radar altimeter freeboard data requires observational data to verify the relation between these two variables. In this study in-situ ice and snow data from 689 observation sites, obtained during the Sever expeditions in the 1980s, have been used to establish an empirical relation between thickness and freeboard of FY ice in late winter. Estimates of mean and variability of snow depth, snow density and ice density were produced on the basis of many field observations. These estimates have been used in the hydrostatic equilibrium equation to retrieve ice thickness as a function of ice freeboard, snow depth and snow/ice density. The accuracy of the ice thickness retrieval has been calculated from the estimated variability in ice and snow parameters and error of ice freeboard measurements. It is found that uncertainties of ice density and freeboard are the major sources of error in ice thickness calculation. For FY ice, retrieval of ≈ 1.0 m (2.0 m thickness has an uncertainty of 46% (37%, and for MY ice, retrieval of 2.4 m (3.0 m thickness has an uncertainty of 20% (18%, assuming that the freeboard error is ± 0.03 m for both ice types. For MY ice the main uncertainty is ice density error, since the freeboard error is relatively smaller than that for FY ice. If the freeboard error can be reduced to 0.01 m by averaging measurements from CryoSat-2, the error in thickness retrieval is reduced to about 32% for a 1.0 m thick FY floe and to about 18% for a 2.4 m thick MY floe. The remaining error is dominated by uncertainty in ice density. Provision of improved ice density data is therefore important for accurate retrieval of ice thickness from CryoSat-2 data.

  18. T, S, and U: Arctic Ocean Change in Response to Sea Ice Loss and Other Forcings

    Science.gov (United States)

    Steele, M.

    2015-12-01

    The Arctic Ocean is changing rapidly, partly in response to sea ice loss and partly from other forcings. Here we consider the three main parameters of physical oceanography: temperature, salinity, and momentum. With regard to temperature, the ocean is experiencing enhanced seasonal surface warming each summer as the ice pack retreats and thins. Some of this summer heat can persist through the winter below the surface mixed layer, although enhanced mixing and other processes can act against this survival. Deeper subsurface layers advected into the Arctic from the North Pacific and North Atlantic Oceans are also warming as these areas respond to warming trends and decadal climate variability. Arctic Ocean warming has implications for the mass balance of the sea ice pack, as well as both marine and coastal terrestrial ecosystems. With regard to salinity, the ocean has just begun to show an overall freshening signal, although with high spatial and temporal variance. This freshening is partly a result of sea ice melt, but also a response to global hydrologic and oceanographic changes. Arctic Ocean freshening enhances the surface stratification, which suppresses upward fluxes of heat and nutrients from below. It also reduces the transfer of momentum (i.e., the stress) from winds to the deep ocean. With regard to momentum, sea ice reduction has created a "looser" ice pack that allows more wind energy to enter the ocean. This effect opposes that of enhanced freshening/stratification when one considers mixing in the upper ocean; the sign and amplitude of the net result is a hot topic in the field. It should also be noted that surface stress in the summer season might actually be declining, as the rough ice pack transitions to a generally smoother sparse pack or open water. In summary, the Arctic Ocean is on the cusp of great change, largely (but not exclusively) forced by changes in the sea ice pack.

  19. Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

    DEFF Research Database (Denmark)

    Forsberg, René; Skourup, Henriette

    2005-01-01

    Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

  20. Atmospheric moisture transport: the bridge between ocean evaporation and Arctic ice melting

    Science.gov (United States)

    Gimeno, L.; Vázquez, M.; Nieto, R.; Trigo, R. M.

    2015-09-01

    Changes in the atmospheric moisture transport have been proposed as a vehicle for interpreting some of the most significant changes in the Arctic region. The increasing moisture over the Arctic during the last decades is not strongly associated with the evaporation that takes place within the Arctic area itself, despite the fact that the sea ice cover is decreasing. Such an increment is consistent and is more dependent on the transport of moisture from the extratropical regions to the Arctic that has increased in recent decades and is expected to increase within a warming climate. This increase could be due either to changes in circulation patterns which have altered the moisture sources, or to changes in the intensity of the moisture sources because of enhanced evaporation, or a combination of these two mechanisms. In this short communication we focus on the more objective assessment of the strong link between ocean evaporation trends and Arctic Sea ice melting. We will critically analyse several recent results suggesting links between moisture transport and the extent of sea ice in the Arctic, this being one of the most distinct indicators of continuous climate change both in the Arctic and on a global scale. To do this we will use a sophisticated Lagrangian approach to develop a more robust framework on some of these previous disconnecting results, using new information and insights. Results reached in this study stress the connection between two climate change indicators, namely an increase in evaporation over source regions (mainly the Mediterranean Sea, the North Atlantic Ocean and the North Pacific Ocean in the paths of the global western boundary currents and their extensions) and Arctic ice melting precursors.

  1. Arctic Technology Evaluation 2014 Oil-in-Ice Demonstration Report

    Science.gov (United States)

    2015-03-01

    USCGC Healy and evaluated their performance in the cold weather environment as part of Arctic Shield. Based on lessons learned in 2013, the RDC...servicing. Additional bottles were provided for cold weather . Figure 3. Aerostat and LRS (left) and aerostat deployed (right). Arctic Technology...long durations through all weather conditions; and communicate real-time data from the surface of the ocean. The model used in Arctic Shield 2014 was

  2. Aragonite undersaturation in the Arctic Ocean: effects of ocean acidification and sea ice melt.

    Science.gov (United States)

    Yamamoto-Kawai, Michiyo; McLaughlin, Fiona A; Carmack, Eddy C; Nishino, Shigeto; Shimada, Koji

    2009-11-20

    The increase in anthropogenic carbon dioxide emissions and attendant increase in ocean acidification and sea ice melt act together to decrease the saturation state of calcium carbonate in the Canada Basin of the Arctic Ocean. In 2008, surface waters were undersaturated with respect to aragonite, a relatively soluble form of calcium carbonate found in plankton and invertebrates. Undersaturation was found to be a direct consequence of the recent extensive melting of sea ice in the Canada Basin. In addition, the retreat of the ice edge well past the shelf-break has produced conditions favorable to enhanced upwelling of subsurface, aragonite-undersaturated water onto the Arctic continental shelf. Undersaturation will affect both planktonic and benthic calcifying biota and therefore the composition of the Arctic ecosystem.

  3. Analysis of an Arctic sea ice loss model in the limit of a discontinuous albedo

    CERN Document Server

    Hill, Kaitlin; Silber, Mary

    2015-01-01

    As Arctic sea ice extent decreases with increasing greenhouse gases, there is a growing interest in whether there could be a bifurcation associated with its loss, and whether there is significant hysteresis associated with that bifurcation. A challenge in answering this question is that the bifurcation behavior of certain Arctic energy balance models have been shown to be sensitive to how ice-albedo feedback is parameterized. We analyze an Arctic energy balance model in the limit as a smoothing parameter associated with ice-albedo feedback tends to zero, which makes the system piecewise-smooth. Our analysis provides a case study where we use the piecewise-smooth system to explore bifurcation behavior of the smooth system. In this case study, we demonstrate that certain qualitative bifurcation behaviors of the smooth system can have nonsmooth counterparts. We use this perspective to systematically search parameter space. For example, we uncover parameter sets for which the largest transition, with increasing g...

  4. Studies on culture condition and extracellular hydrolase of psychrophilic bacteria from Arctic sea ice

    Institute of Scientific and Technical Information of China (English)

    Li Xiaohui; Yu Yong; Li Huirong; Zhang Lin; Jiang Xinyin; Ren Daming

    2008-01-01

    Arctic sea ice in the polar region provides a cold habitat for microbial community.Arctic sea ice microorganisms are revealed to be of considerable importance in basic research and potential in biotechnological application.This paper investigated the culture condition and extracellular hydrolase of 14 strains of different Arctic sea ice bacteria.The results showed that optimal growth temperature of strains is 15 ℃ or 20 ℃.The optimal pH is about 8.0.They hardly grow at acid condition.3% NaCl is necessary for better growth.These strains have different abilities in producing amylase,protease,cellulase and lipase.Pseudoalteronomas sp.Bsi429 and Pseudoalteronomas sp.Bsi539 produced both cellulose,protease and lipase.These results provide a basis for further developing and exploiting the cold adapted marine enzyme resources.

  5. Estimation of Arctic Sea Ice Freeboard and Thickness Using CryoSat-2

    Science.gov (United States)

    Lee, S.; Im, J.; Kim, J. W.; Kim, M.; Shin, M.

    2014-12-01

    Arctic sea ice is one of the significant components of the global climate system as it plays a significant role in driving global ocean circulation. Sea ice extent has constantly declined since 1980s. Arctic sea ice thickness has also been diminishing along with the decreasing sea ice extent. Because extent and thickness, two main characteristics of sea ice, are important indicators of the polar response to on-going climate change. Sea ice thickness has been measured with numerous field techniques such as surface drilling and deploying buoys. These techniques provide sparse and discontinuous data in spatiotemporal domain. Spaceborne radar and laser altimeters can overcome these limitations and have been used to estimate sea ice thickness. Ice Cloud and land Elevation Satellite (ICEsat), a laser altimeter provided data to detect polar area elevation change between 2003 and 2009. CryoSat-2 launched with Synthetic Aperture Radar (SAR)/Interferometric Radar Altimeter (SIRAL) in April 2010 can provide data to estimate time-series of Arctic sea ice thickness. In this study, Arctic sea ice freeboard and thickness between 2011 and 2014 were estimated using CryoSat-2 SAR and SARIn mode data that have sea ice surface height relative to the reference ellipsoid WGS84. In order to estimate sea ice thickness, freeboard, i.e., elevation difference between the top of sea ice surface should be calculated. Freeboard can be estimated through detecting leads. We proposed a novel lead detection approach. CryoSat-2 profiles such as pulse peakiness, backscatter sigma-0, stack standard deviation, skewness and kurtosis were examined to distinguish leads from sea ice. Near-real time cloud-free MODIS images corresponding to CryoSat-2 data measured were used to visually identify leads. Rule-based machine learning approaches such as See5.0 and random forest were used to identify leads. The proposed lead detection approach better distinguished leads from sea ice than the existing approaches

  6. Cloud radiative forcing sensitivity to Arctic synoptic regimes, surface type, cloud phase and cloud properties during the Fall 2014 Arctic Radiation, IceBridge and Sea-Ice Experiment (ARISE)

    Science.gov (United States)

    Segal-Rosenheimer, Michal; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor; LeBanc, Samuel; Schmidt, Sebastian; Song, Shi; Bucholtz, Anthony; Reid, Elizabeth; Anderson, Bruce; Corr, Chelsea; Smith, William L.; Kato, Seiji; Spangenberg, Douglas A.; Hofton, Michelle; Moore, Richard; Winstead, Edward; Thornhill, Lee K.

    2015-04-01

    stability regimes and cloud property range combinations. We also evaluate sensitivity of CRF to our clear sky estimations based on the prevailing atmospheric condition and ice cover. Finally, we compare synoptic regimes and cloud cover amount for September 2014 with previous years (2010-2013) to put our interpretations in a broader context. Barton, N. P.et al., (2012). Arctic synoptic regimes: Comparing domain-wide Arctic cloud observations with CAM4 and CAM5 during similar dynamics. Journal of Geophysical Research, 117(D15), D15205. doi:10.1029/2012JD017589 Bennartz, R. et al., (2013). July 2012 Greenland melt extent enhanced by low-level liquid clouds. Nature, 496(7443), 83-6. doi:10.1038/nature12002 Sedlar, J, et al., (2012). On the Relationship between Thermodynamic Structure and Cloud Top, and Its Climate Significance in the Arctic. Journal of Climate, 25(7), 2374-2393. doi:10.1175/JCLI-D-11-00186.1 Shupe, M. et al.,. (2004). Cloud Radiative Forcing of the Arctic Surface : The Influence of Cloud Properties,Surface Albedo , and Solar Zenith Angle. Journal of Climate, 17, 616-628. Taylor, P. et al., (2014), Interactions Between Arctic Sea Ice, Clouds, and the Circulation, AGU Fall Meeting, GC12A-07, 2014 Wenshan Wang and Charles S. Zender, Improving Estimates of Cloud Radiative Forcing over Greenland, AGU Fall Meeting, C21C-0375, 2014

  7. How Will Aerosol-Cloud Interactions Change in an Ice-Free Arctic Summer?

    Science.gov (United States)

    Gilgen, Anina; Katty Huang, Wan Ting; Ickes, Luisa; Lohmann, Ulrike

    2016-04-01

    Future temperatures in the Arctic are expected to increase more than the global mean temperature, which will lead to a pronounced retreat in Arctic sea ice. Before mid-century, most sea ice will likely have vanished in late Arctic summers. This will allow ships to cruise in the Arctic Ocean, e.g. to shorten their transport passage or to extract oil. Since both ships and open water emit aerosol particles and precursors, Arctic clouds and radiation may be affected via aerosol-cloud and cloud-radiation interactions. The change in radiation feeds back on temperature and sea ice retreat. In addition to aerosol particles, also the temperature and the open ocean as a humidity source should have a strong effect on clouds. The main goal of this study is to assess the impact of sea ice retreat on the Arctic climate with focus on aerosol emissions and cloud properties. To this purpose, we conducted ensemble runs with the global climate model ECHAM6-HAM2 under present-day and future (2050) conditions. ECHAM6-HAM2 was coupled with a mixed layer ocean model, which includes a sea ice model. To estimate Arctic aerosol emissions from ships, we used an elaborated ship emission inventory (Peters et al. 2011); changes in aerosol emissions from the ocean are calculated online. Preliminary results show that the sea salt aerosol and the dimethyl sulfide burdens over the Arctic Ocean significantly increase. While the ice water path decreases, the total water path increases. Due to the decrease in surface albedo, the cooling effect of the Arctic clouds becomes more important in 2050. Enhanced Arctic shipping has only a very small impact. The increase in the aersol burden due to shipping is less pronounced than the increase due to natural emissions even if the ship emissions are increased by a factor of ten. Hence, there is hardly an effect on clouds and radiation caused by shipping. References Peters et al. (2011), Atmos. Chem. Phys., 11, 5305-5320

  8. Satellite and In Situ Observations of Arctic Sea Ice Floe Breakup and Melt

    Science.gov (United States)

    Richter-Menge, J.; Perovich, D. K.

    2013-12-01

    During the summer melt season the Arctic sea ice cover undergoes a major transformation. In spring the ice cover consists of large, angular floes covered by snow. By late-summer it is an ensemble of smaller rounded ice floes embedded in a lace of open water, with a surface that is a mix of bare ice and melt ponds. We integrated in situ observations of sea ice mass balance with high resolution, visible satellite imagery from April to October 2013 to follow the evolution of the seasonal marginal ice zone in the Beaufort Sea. The autonomous sea ice mass balance buoy recorded a time series of ice temperature, ice growth, snow depth, ice thickness, and surface and bottom melting. The satellite images were collected by tracking the movement of the buoy as it drifted with the ice cover. Each image covered an area of about 250 km2 with a spatial resolution of just over one meter. From the images we computed ice concentration, pond fraction, floe perimeter, pond fraction, floe and pond size distribution, and the timing of melt and freezeup. Ridges and cracks formed in winter were followed into summer to investigate their effect on the floe size distribution. Measurements from the ice mass balance buoys are scaled up using the imagery to generate area estimates of the evolution of the sea ice mass loss during summer melt. There was an increase in pond coverage starting in mid-June and an increase in floe perimeter as melt proceeded into July and August.

  9. Persistence of bacterial and archaeal communities in sea ice through an Arctic winter.

    Science.gov (United States)

    Collins, R Eric; Rocap, Gabrielle; Deming, Jody W

    2010-07-01

    The structure of bacterial communities in first-year spring and summer sea ice differs from that in source seawaters, suggesting selection during ice formation in autumn or taxon-specific mortality in the ice during winter. We tested these hypotheses by weekly sampling (January-March 2004) of first-year winter sea ice (Franklin Bay, Western Arctic) that experienced temperatures from -9 degrees C to -26 degrees C, generating community fingerprints and clone libraries for Bacteria and Archaea. Despite severe conditions and significant decreases in microbial abundance, no significant changes in richness or community structure were detected in the ice. Communities of Bacteria and Archaea in the ice, as in under-ice seawater, were dominated by SAR11 clade Alphaproteobacteria and Marine Group I Crenarchaeota, neither of which is known from later season sea ice. The bacterial ice library contained clones of Gammaproteobacteria from oligotrophic seawater clades (e.g. OM60, OM182) but no clones from gammaproteobacterial genera commonly detected in later season sea ice by similar methods (e.g. Colwellia, Psychrobacter). The only common sea ice bacterial genus detected in winter ice was Polaribacter. Overall, selection during ice formation and mortality during winter appear to play minor roles in the process of microbial succession that leads to distinctive spring and summer sea ice communities.