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Vivier, F, J Hutchings, Y Kawaguchi, T Kikuchi, J Morison, A Lourenço, T Noguchi. (2016). Sea-ice melt onset associated with lead opening during the spring/summer transition near the North Pole . J. Geophys. Res., 121(4), 2499–2522.
Abstract: In the central Arctic Ocean, autonomous observations of the ocean mixed layer and ice documented the transition from cold spring to early summer in 2011. Ice-motion measurements using GPS drifters captured three events of lead opening and ice ridge formation in May and June. Satellite sea ice concentration observations suggest that locally observed lead openings were part of a larger-scale pattern. We clarify how these ice deformation events are linked with the onset of basal sea ice melt, which preceded surface melt by 20 days. Observed basal melt and ocean warming are consistent with the available input of solar radiation into leads, once the advent of mild atmospheric conditions prevents lead refreezing. We use a one-dimensional numerical simulation incorporating a Local Turbulence Closure scheme to investigate the mechanisms controlling basal melt and upper ocean warming. According to the simulation, a combination of rapid ice motion and increased solar energy input at leads promotes basal ice melt, through enhanced mixing in the upper mixed layer, while slow ice motion during a large lead opening in mid-June produced a thin, low-density surface layer. This enhanced stratification near the surface facilitates storage of solar radiation within the thin layer, instead of exchange with deeper layers, leading to further basal ice melt preceding the upper surface melt.
Programme: 1015
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. (2017). Millimeter-Wave Radar Sensor for Snow Height Measurements (Vol. 55).
Keywords: Frequency-modulated continuous-wave (FMCW) radar high accuracy Laser radar Measurement by laser beam millimeter wave Millimeter wave radar Radar measurements range detection Snow snow height snow thickness Temperature measurement
Programme: 1015
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. (2015). The Louvain-La-Neuve sea ice model LIM3.6: global and regional capabilities (Vol. 8). Bachelor's thesis, , .
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Douglas Thomas A, Domine Florent, Barret Manuel, Anastasio Cort, Beine Harry J, Bottenheim Jan, Grannas Amanda, Houdier Stephan, Netcheva Stoyka, Rowland Glenn, Staebler Ralf, Steffen Alexandra,. (2012). Frost flowers growing in the Arctic ocean-atmosphere-sea ice-snow interface: 1. Chemical composition. J. Geophys. Res., 117, D00R09 ST -.
Abstract: Frost flowers, intricate featherlike crystals that grow on refreezing sea ice leads, have been implicated in lower atmospheric chemical reactions. Few studies have presented chemical composition information for frost flowers over time and many of the chemical species commonly associated with Polar tropospheric reactions have never been reported for frost flowers. We undertook this study on the sea ice north of Barrow, Alaska to quantify the major ion, stable oxygen and hydrogen isotope, alkalinity, light absorbance by soluble species, organochlorine, and aldehyde composition of seawater, brine, and frost flowers. For many of these chemical species we present the first measurements from brine or frost flowers. Results show that major ion and alkalinity concentrations, stable isotope values, and major chromophore (NO3- and H2O2) concentrations are controlled by fractionation from seawater and brine. The presence of these chemical species in present and future sea ice scenarios is somewhat predictable. However, aldehydes, organochlorine compounds, light absorbing species, and mercury (part 2 of this research and Sherman et al. (2012)) are deposited to frost flowers through less predictable processes that probably involve the atmosphere as a source. The present and future concentrations of these constituents in frost flowers may not be easily incorporated into future sea ice or lower atmospheric chemistry scenarios. Thinning of Arctic sea ice will likely present more open sea ice leads where young ice, brine, and frost flowers form. How these changing ice conditions will affect the interactions between ice, brine, frost flowers and the lower atmosphere is unknown.
Keywords: frost flowers polar atmospheric chemistry sea ice 0738 Cryosphere: Ice (1863) 0750 Cryosphere: Sea ice (4540) 0793 Cryosphere: Biogeochemistry (0412, 0414, 1615, 4805, 4912) 1022 Geochemistry: Composition of the hydrosphere 1050 Geochemistry: Marine geochemistry (4835, 4845, 4850),
Programme: 1017
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Domine Florent, Gallet Jean-Charles, Barret Manuel, Houdier Stphan, Voisin Didier, Douglas Thomas A, Blum Joel D, Beine Harry J, Anastasio Cort, Bron Franois-Marie, . (2011). The specific surface area and chemical composition of diamond dust near Barrow, Alaska
. J. Geophys. Res., 116, D00R06–.
Keywords: absorption spectra, aldehydes, dissolved organic carbon, ionic composition, mercury, specific surface area, 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906), 0317 Atmospheric Composition and Structure: Chemical kinetic and photochemical properties, 0330 Atmospheric Composition and Structure: Geochemical cycles (1030), 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry, 0736 Cryosphere: Snow (1827, 1863),
Programme: 1017
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France J L, King M D, Lee-Taylor J, Beine H J, Ianniello A, Domine F, MacArthur A,. (2011). J. Geophys. Res., 116, F04013 ST -.
Keywords: Arctic fluxes hydroxyl radical nitrate snowpack 0736 Cryosphere: Snow (1827, 1863) 0798 Cryosphere: Modeling (1952, 4316),
Programme: 1017
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Barret Manuel, Domine Florent, Houdier Stephan, Gallet Jean-Charles, Weibring Petter, Walega James, Fried Alan, Richter Dirk, . (2011). Formaldehyde in the Alaskan Arctic snowpack: Partitioning and physical processes involved in air-snow exchanges
. J. Geophys. Res., 116, D00R03–.
Abstract: The snowpack is a photochemically active medium which produces numerous key reactive species involved in the atmospheric chemistry of polar regions. Formaldehyde (HCHO) is one such reactive species produced in the snow, and which can be released to the atmospheric boundary layer. Based on atmospheric and snow measurements, this study investigates the physical processes involved in the HCHO air-snow exchanges observed during the OASIS 2009 field campaign at Barrow, Alaska. HCHO concentration changes in a fresh diamond dust layer are quantitatively explained by the equilibration of a solid solution of HCHO in ice, through solid-state diffusion of HCHO within snow crystals. Because diffusion of HCHO in ice is slow, the size of snow crystals is a major variable in the kinetics of exchange and the knowledge of the snow specific surface area is therefore crucial. Air-snow exchanges of HCHO can thus be explained without having to consider processes taking place in the quasi-liquid layer present at the surface of ice crystals. A flux of HCHO to the atmosphere was observed simultaneously with an increase of HCHO concentration in snow, indicating photochemical production in surface snow. This study also suggests that the difference in bromine chemistry between Alert (Canadian Arctic) and Barrow leads to different snow composition and post-deposition evolutions. The highly active bromine chemistry at Barrow probably leads to low HCHO concentrations at the altitude where diamond dust formed. Precipitated diamond dust was subsequently undersaturated with respect to thermodynamic equilibrium, which contrasts to what was observed elsewhere in previous studies.
Keywords: adsorption, carbonyls, diffusion, halogen, solid-solution, 0322 Atmospheric Composition and Structure: Constituent sources and sinks, 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry, 0736 Cryosphere: Snow (1827, 1863), 3307 Atmospheric Processes: Boundary layer processes, 9315 Geographic Location: Arctic region (0718, 4207),
Programme: 1017
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Voisin Didier, Jaffrezo Jean-Luc, Houdier Stphan, Barret Manuel, Cozic Julie, King Martin D, France James L, Reay Holly J, Grannas Amanda, Kos Gregor, Ariya Parisa A, Beine Harry J, Domine Florent, . (2012). Carbonaceous species and humic like substances (HULIS) in Arctic snowpack during OASIS field campaign in Barrow
. J. Geophys. Res., 117, D00R19–.
Abstract: Snowpacks contain many carbonaceous species that can potentially impact on snow albedo and arctic atmospheric chemistry. During the OASIS field campaign, in March and April 2009, Elemental Carbon (EC), Water insoluble Organic Carbon (WinOC) and Dissolved Organic Carbon (DOC) were investigated in various types of snow: precipitating snows, remobilized snows, wind slabs and depth hoars. EC was found to represent less than 5% of the Total Carbon Content (TCC = EC + WinOC + DOC), whereas WinOC was found to represent an unusual 28 to 42% of TCC. Snow type was used to infer physical processes influencing the evolution of different fractions of DOC. DOC is highest in soil influenced indurated depth hoar layers due to specific wind related formation mechanisms in the early season. Apart from this specific snow type, DOC is found to decrease from precipitating snow to remobilized snow to regular depth hoar. This decrease is interpreted as due to cleaving photochemistry and physical equilibration of the most volatile fraction of DOC. Depending on the relative proportions of diamond dust and fresh snow in the deposition of the seasonal snowpack, we estimate that 31 to 76% of DOC deposited to the snowpack is reemitted back to the boundary layer. Under the assumption that this reemission is purely photochemical, we estimate an average flux of VOC out of the snowpack of 20 to 170 μgC m-2 h-1. Humic like substances (HULIS), short chain diacids and aldehydes are quantified, and showed to represent altogether a modest (<20%) proportion of DOC, and less than 10% of DOC + WinOC. HULIS optical properties are measured and could be consistent with aged biomass burning or a possible marine source.
Keywords: HULIS, OASIS, carbonaceous species, snow chemistry, snow metamorphism, 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906), 0706 Cryosphere: Active layer, 0736 Cryosphere: Snow (1827, 1863),
Programme: 1017
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Morin S, Erbland J, Savarino J, Domine F, Bock J, Friess U, Jacobi H-W, Sihler H, Martins J M F, . (2012). An isotopic view on the connection between photolytic emissions of NOx from the Arctic snowpack and its oxidation by reactive halogens
. J. Geophys. Res., 117, D00R08–.
Keywords: halogen, isotopes, nitrate, ozone, 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906), 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry, 0454 Biogeosciences: Isotopic composition and chemistry (1041, 4870), 0736 Cryosphere: Snow (1827, 1863), 9315 Geographic Location: Arctic region (0718, 4207),
Programme: 1017
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Gouttevin I, Menegoz M, Domin F, Krinner G, Koven C, Ciais P, Tarnocai C, Boike J, . (2012). How the insulating properties of snow affect soil carbon distribution in the continental pan-Arctic area
. J. Geophys. Res., 117(G2), G02020–.
Abstract: We demonstrate the effect of an ecosystem differentiated insulation by snow on the soil thermal regime and on the terrestrial soil carbon distribution in the pan-Arctic area. This is done by means of a sensitivity study performed with the land surface model ORCHIDEE, which furthermore provides a first quantification of this effect. Based on field campaigns reporting higher thermal conductivities and densities for the tundra snowpack than for taiga snow, two distributions of near-equilibrium soil carbon stocks are computed, one relying on uniform snow thermal properties and the other using ecosystem-differentiated snow thermal properties. Those modeled distributions strongly depend on soil temperature through decomposition processes. Considering higher insulation by snow in taiga areas induces warmer soil temperatures by up to 12 K in winter at 50 cm depth. This warmer soil signal persists over summer with a temperature difference of up to 4 K at 50 cm depth, especially in areas exhibiting a thick, enduring snow cover. These thermal changes have implications on the modeled soil carbon stocks, which are reduced by 8% in the pan-Arctic continental area when the vegetation-induced variations of snow thermal properties are accounted for. This is the result of diverse and spatially heterogeneous ecosystem processes: where higher soil temperatures lift nitrogen limitation on plant productivity, tree plant functional types thrive whereas light limitation and enhanced water stress are the new constrains on lower vegetation, resulting in a reduced net productivity at the pan-Arctic scale. Concomitantly, higher soil temperatures yield increased respiration rates (+22% over the study area) and result in reduced permafrost extent and deeper active layers which expose greater volumes of soil to microbial decomposition. The three effects combine to produce lower soil carbon stocks in the pan-Arctic terrestrial area. Our study highlights the role of snow in combination with vegetation in shaping the distribution of soil carbon and permafrost at high latitudes.
Keywords: Arctic, land-surface model, permafrost, snow, snow insulation, soil carbon, 0414 Biogeosciences: Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912), 0475 Biogeosciences: Permafrost, cryosphere, and high-latitude processes (0702, 0716), 1622 Global Change: Earth system modeling (1225, 4316),
Programme: 1017
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