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Mats A Granskog - One of the best experts on this subject based on the ideXlab platform.
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observations of flooding and snow Ice Formation in a thinner arctic sea Ice regime during the n Ice2015 campaign influence of basal Ice melt and storms
Journal of Geophysical Research, 2017Co-Authors: Christine Provost, Nathalie Sennechael, Jonas Miguet, Polona Itkin, Anja Rosel, Zoe Koenig, Nicolas Villacierosrobineau, Mats A GranskogAbstract:Seven Ice mass balance instruments deployed near 83°N on different first-year and second-year Ice floes, representing variable snow and Ice conditions, documented the evolution of snow and Ice conditions in the Arctic Ocean north of Svalbard in January–March 2015. Frequent profiles of temperature and thermal diffusivity proxy were recorded to distinguish changes in snow depth and Ice thickness with 2 cm vertical resolution. Four instruments documented flooding and snow-Ice Formation. Flooding was clearly detectable in the simultaneous changes in thermal diffusivity proxy, increased temperature, and heat propagation through the underlying Ice. Slush then progressively transformed into snow-Ice. Flooding resulted from two different processes: (i) after storm-induced breakup of snow-loaded floes and (ii) after loss of buoyancy due to basal Ice melt. In the case of breakup, when the Ice was cold and not permeable, rapid flooding, probably due to lateral intrusion of seawater, led to slush and snow-Ice layers at the ocean freezing temperature (−1.88°C). After the storm, the instruments documented basal sea-Ice melt over warm Atlantic waters and ocean-to-Ice heat flux peaked at up to 400 W m−2. The warm Ice was then permeable and flooding was more gradual probably involving vertical intrusion of brines and led to colder slush and snow-Ice (−3°C). The N-Ice2015 campaign provided the first documentation of significant flooding and snow-Ice Formation in the Arctic Ice pack as the slush partially refroze. Snow-Ice Formation may become a more frequently observed process in a thinner Ice Arctic.
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nutrient status of baltic sea Ice evidence for control by snow Ice Formation Ice permeability and Ice algae
Journal of Geophysical Research, 2003Co-Authors: Mats A Granskog, Hermanni Kaartokallio, Kunio ShirasawaAbstract:[1] Samples of land-fast sea Ice collected along the Finnish coast of the Baltic Sea, between latitudes 60.2°N and 65.7°N, in January to April 2000 were analyzed for physical, biological, and chemical parameters. Both spatial and temporal variability were investigated. Snow-Ice contributed in average a third of the total Ice thickness, while the snow fraction (by mass) of the Ice was 20% on average. Snow-Ice Formation increased the nitrogen concentrations substantially, mainly in the upper parts of the Ice cover. Phosphorus on the other hand was controlled by biological uptake, with distinct maxima in the bottommost parts of the Ice cover. The chlorophyll-a concentrations were dependent on the physical properties of the Ice to some extent. In more saline waters the chlorophyll-a concentrations in the Ice were variable (1–17 μg l−1). However, in the less saline waters of the Bothnian Bay the concentrations were generally considerably lower (<1 μg l−1) than elsewhere. This is presumably caused by Formation of Ice of low salinity, due to the low ambient salinity in the area and the under-Ice flow of river waters, and Formation of Ice that has no habitable space for Ice algae. Atmospheric nutrients possibly enhance the magnitude of the Ice algae bloom, through downward flushing of surface deposited nutrients during periods when the Ice was permeable. We surmise that atmospheric supply of nutrients plays an important role in biological productivity within the Baltic Sea Ice sheet and potentially also in under-Ice waters.
Hermanni Kaartokallio - One of the best experts on this subject based on the ideXlab platform.
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Ice Formation and growth shape bacterial community structure in baltic sea drift Ice
FEMS Microbiology Ecology, 2015Co-Authors: Eeva Eronenrasimus, Christina Lyra, Jannemarkus Rintala, Klaus Jurgens, Vilma Ikonen, Hermanni KaartokallioAbstract:Drift Ice, open water and under-Ice water bacterial communities covering several developmental stages from open water to thick Ice were studied in the northern Baltic Sea. The bacterial communities were assessed with 16S rRNA gene terminal-restriction fragment length polymorphism and cloning, together with bacterial abundance and production measurements. In the early stages, open water and pancake Ice were dominated by Alphaproteobacteria and Actinobacteria, which are common bacterial groups in Baltic Sea wintertime surface waters. The pancake Ice bacterial communities were similar to the open-water communities, suggesting that the parent water determines the sea-Ice bacterial community in the early stages of sea-Ice Formation. In consolidated young and thick Ice, the bacterial communities were significantly different from water bacterial communities as well as from each other, indicating community development in Baltic Sea drift Ice along with Ice-type changes. The thick Ice was dominated by typical sea-Ice genera from classes Flavobacteria and Gammaproteobacteria, similar to those in polar sea-Ice bacterial communities. Since the thick Ice bacterial community was remarkably different from that of the parent seawater, results indicate that thick Ice bacterial communities were recruited from the rarer members of the seawater bacterial community.
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bacterial community dynamics and activity in relation to dissolved organic matter availability during sea Ice Formation in a mesocosm experiment
EPIC3MicrobiologyOpen John Wiley & sons pp. 1-18 ISSN: 2045-8827, 2014Co-Authors: Eeva Eronenrasimus, Hermanni Kaartokallio, Riitta Autio, H Kuosa, Gerhard Dieckmann, D N Thomas, Christina LyraAbstract:The structure of sea-Ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea Ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea Ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during Ice Formation, bacterial succession was studied in under Ice water and sea Ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-Ice bacterial communities developed in Ice formed in both unenriched and DOM-enriched seawater (0-6 days). I³-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea Ice. The bacterial communities in the unenriched waters and Ice consisted of the classes Flavobacteria, I±- and I³-Proteobacteria, which are frequently found in natural sea Ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during Ice Formation.
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dissolved extracellular polymeric substances deps dynamics and bacterial growth during sea Ice Formation in an Ice tank study
Polar Biology, 2012Co-Authors: Shazia N Aslam, Graham J C Underwood, Hermanni Kaartokallio, L Norman, Riitta Autio, Michael Fischer, H Kuosa, Gerhard Dieckmann, D N ThomasAbstract:Extracellular polymeric substances (EPS) are known to help microorganisms to survive under extreme conditions in sea Ice. High concentrations of EPS are reported in sea Ice from both poles; however, production and dynamics of EPS during sea Ice Formation have been little studied to date. This investigation followed the production and partitioning of existing and newly formed dissolved organic matter (DOM) including dissolved carbohydrates (dCHO), dissolved uronic acids (dUA) and dissolved EPS (dEPS), along with bacterial abundances during early stages of Ice Formation. Sea Ice was formed from North Sea water with (A) ambient DOM (NSW) and (B) with additional algal-derived DOM (ADOM) in a 6d experiment in replicated mesocosms. In ADOM seawater, total bacterial numbers (TBN) increased throughout the experiment, whereas bacterial growth occurred for 5d only in the NSW seawater. TBN progressively decreased within developing sea Ice but with a 2-fold greater decline in NSW compared to ADOM Ice. There were significant increases in the concentrations of dCHO in Ice. Percentage contribution of dEPS was highest (63%) in the colder, uppermost parts in ADOM Ice suggesting the development of a cold-adapted community, producing dEPS possibly for cryo-protection and/or protection from high salinity brines. We conclude that in the early stages of Ice Formation, allochthonous organic matter was incorporated from parent seawater into sea Ice and that once Ice Formation had established, there were significant changes in the concentrations and composition of dissolved organic carbon pool, resulting mainly from the production of autochthonous DOM by the bacteria.
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nutrient status of baltic sea Ice evidence for control by snow Ice Formation Ice permeability and Ice algae
Journal of Geophysical Research, 2003Co-Authors: Mats A Granskog, Hermanni Kaartokallio, Kunio ShirasawaAbstract:[1] Samples of land-fast sea Ice collected along the Finnish coast of the Baltic Sea, between latitudes 60.2°N and 65.7°N, in January to April 2000 were analyzed for physical, biological, and chemical parameters. Both spatial and temporal variability were investigated. Snow-Ice contributed in average a third of the total Ice thickness, while the snow fraction (by mass) of the Ice was 20% on average. Snow-Ice Formation increased the nitrogen concentrations substantially, mainly in the upper parts of the Ice cover. Phosphorus on the other hand was controlled by biological uptake, with distinct maxima in the bottommost parts of the Ice cover. The chlorophyll-a concentrations were dependent on the physical properties of the Ice to some extent. In more saline waters the chlorophyll-a concentrations in the Ice were variable (1–17 μg l−1). However, in the less saline waters of the Bothnian Bay the concentrations were generally considerably lower (<1 μg l−1) than elsewhere. This is presumably caused by Formation of Ice of low salinity, due to the low ambient salinity in the area and the under-Ice flow of river waters, and Formation of Ice that has no habitable space for Ice algae. Atmospheric nutrients possibly enhance the magnitude of the Ice algae bloom, through downward flushing of surface deposited nutrients during periods when the Ice was permeable. We surmise that atmospheric supply of nutrients plays an important role in biological productivity within the Baltic Sea Ice sheet and potentially also in under-Ice waters.
Eeva Eronenrasimus - One of the best experts on this subject based on the ideXlab platform.
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Ice Formation and growth shape bacterial community structure in baltic sea drift Ice
FEMS Microbiology Ecology, 2015Co-Authors: Eeva Eronenrasimus, Christina Lyra, Jannemarkus Rintala, Klaus Jurgens, Vilma Ikonen, Hermanni KaartokallioAbstract:Drift Ice, open water and under-Ice water bacterial communities covering several developmental stages from open water to thick Ice were studied in the northern Baltic Sea. The bacterial communities were assessed with 16S rRNA gene terminal-restriction fragment length polymorphism and cloning, together with bacterial abundance and production measurements. In the early stages, open water and pancake Ice were dominated by Alphaproteobacteria and Actinobacteria, which are common bacterial groups in Baltic Sea wintertime surface waters. The pancake Ice bacterial communities were similar to the open-water communities, suggesting that the parent water determines the sea-Ice bacterial community in the early stages of sea-Ice Formation. In consolidated young and thick Ice, the bacterial communities were significantly different from water bacterial communities as well as from each other, indicating community development in Baltic Sea drift Ice along with Ice-type changes. The thick Ice was dominated by typical sea-Ice genera from classes Flavobacteria and Gammaproteobacteria, similar to those in polar sea-Ice bacterial communities. Since the thick Ice bacterial community was remarkably different from that of the parent seawater, results indicate that thick Ice bacterial communities were recruited from the rarer members of the seawater bacterial community.
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bacterial community dynamics and activity in relation to dissolved organic matter availability during sea Ice Formation in a mesocosm experiment
EPIC3MicrobiologyOpen John Wiley & sons pp. 1-18 ISSN: 2045-8827, 2014Co-Authors: Eeva Eronenrasimus, Hermanni Kaartokallio, Riitta Autio, H Kuosa, Gerhard Dieckmann, D N Thomas, Christina LyraAbstract:The structure of sea-Ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea Ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea Ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during Ice Formation, bacterial succession was studied in under Ice water and sea Ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-Ice bacterial communities developed in Ice formed in both unenriched and DOM-enriched seawater (0-6 days). I³-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea Ice. The bacterial communities in the unenriched waters and Ice consisted of the classes Flavobacteria, I±- and I³-Proteobacteria, which are frequently found in natural sea Ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during Ice Formation.
Kay I Ohshima - One of the best experts on this subject based on the ideXlab platform.
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a numerical investigation of Formation and variability of antarctic bottom water off cape darnley east antarctica
Journal of Physical Oceanography, 2014Co-Authors: Yoshihiro Nakayama, Kay I Ohshima, Yasushi Fukamachi, Yoshimasa Matsumura, Hiroyasu HasumiAbstract:AbstractAt several locations around Antarctica, dense water is formed as a result of intense sea Ice Formation. When this dense water becomes sufficiently denser than the surrounding water, it descends the continental slope and forms Antarctic Bottom Water (AABW). This study presents the AABW Formation off the coast of Cape Darnley [Cape Darnley Bottom Water (CDBW)] in East Antarctica, using a nonhydrostatic model. The model is forced for 8 months by a temporally uniform surface salt flux (because of sea Ice Formation) estimated from Advanced Microwave Scanning Radiometer for Earth Observing System (EOS; AMSR-E) data and a heat budget calculation. The authors reproduce AABW Formation and associated periodic downslope flows of dense water. Descending pathways of dense water are largely determined by the topography; most dense water flows into depressions on the continental shelf, advects onto the continental slope, and is steered downslope to greater depths by the canyons. Intense sea Ice Formation is the ...
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physical structural and isotopic characteristics and growth processes of fast sea Ice in lutzow holm bay antarctica
Journal of Geophysical Research, 1997Co-Authors: Toshiyuki Kawamura, Kay I Ohshima, Takatoshi Takizawa, Shuki UshioAbstract:A sea-Ice/ocean study was conducted off Queen Maud Land and Enderby Land, Antarctica, from 1990 to 1991 by the Japanese Antarctic Research Expedition. Observations of multiyear land fast sea Ice were made in Lutzow-Holm Bay over a period of 2 years to determine the snow and Ice characteristics and Ice growth processes. The snow depth in the bay reached large values of 1.0 to 1.5 m during the winter season at offshore locations. From the analysis of Ice thickness measurements, it is confirmed that the fast Ice with deep snow cover grew little in winter but substantially thickened during the summer months. On the basis of Ice core structure, salinity, and stable isotopic composition, we conclude that the summer growth was caused by upward growth at the top of the Ice to which snow Ice and superimposed Ice Formation contribute. These processes were the primary contributors to sea-Ice growth and characteristics only where the snow accumulation was large. In areas of low snow accumulation, there was no surface growth. Superimposed Ice Formation on sea Ice in Antarctica has not been reported previously. Evidence for snow cover melting, which is a prerequisite for superimposed Ice Formation, was also found.
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SEA-Ice Formation AND WATER STRUCTURES IN COASTAL POLYNYAS OFF LUTZOW-HOLM BAY AND BREID BAY
The Institute of Low Temperature Science Hokkaido University, 1994Co-Authors: ウシオ シュウキ, Kay I Ohshima, タキザワ タカトシ, カワムラ トシユキ, Shuki Ushio, Takatoshi Takizawa, Toshiyuki KawamuraAbstract:In a coastal region where strong offshore winds and currents prevail, newly-formed sea Ice is removed as quickly as it forms. Consequently, the open water areas are maintained for a long period of time, despite considerable Ice production. Such open waters, or coastal polynyas, release latent heat of fusion of Ice and moisture from the ocean to the atmosphere. High-salinity brine is also excluded to the ocean by sea-Ice Formation. The polynyas may have great influence on the atmosphere-ocean interaction. Satellite images have suggested the presence of winter coastal polynyas between fast Ice (or Ice shelf) and pack Ice regions off Lutzow-Holm Bay and Breid Bay, Antarctica. In 1990-1992,oceanographic observations were intensively conducted by the 31st and 32nd Japanese Antarctic Research Expeditions to understand sea-Ice and oceanic processes in the polynya off Lutzow-Holm Bay. Under windy conditions, aircraft observations revealed many new-Ice streaks formed approximately parallel to the wind direction and generation of frost smoke from the open water. Water temperature profiles in the polynya were obtained by using aircraft-deployed expendable bathythermographs (AXBT) with a depth capability of 460m. Based on the temperature data, it is estimated that the thickness of the convective-mixed layer with its freezing point is 350-450m. The mixed layer has a tendency to deepen in winter. According to the austral summer oceanographic data acquired on board the Icebreakers FUJI and SHIRASE, winter convective-mixed layers remain cold and oxygen-rich in the polynya regions. These mixed layers were evidently thicker than those in pack Ice regions. Such water structures were also formed in the Breid Bay polynya. The thick convective-mixed layer is considered to reflect the processes of vigorous sea-Ice production and the resultant convective mixing in the open polynyas
Shuki Ushio - One of the best experts on this subject based on the ideXlab platform.
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physical structural and isotopic characteristics and growth processes of fast sea Ice in lutzow holm bay antarctica
Journal of Geophysical Research, 1997Co-Authors: Toshiyuki Kawamura, Kay I Ohshima, Takatoshi Takizawa, Shuki UshioAbstract:A sea-Ice/ocean study was conducted off Queen Maud Land and Enderby Land, Antarctica, from 1990 to 1991 by the Japanese Antarctic Research Expedition. Observations of multiyear land fast sea Ice were made in Lutzow-Holm Bay over a period of 2 years to determine the snow and Ice characteristics and Ice growth processes. The snow depth in the bay reached large values of 1.0 to 1.5 m during the winter season at offshore locations. From the analysis of Ice thickness measurements, it is confirmed that the fast Ice with deep snow cover grew little in winter but substantially thickened during the summer months. On the basis of Ice core structure, salinity, and stable isotopic composition, we conclude that the summer growth was caused by upward growth at the top of the Ice to which snow Ice and superimposed Ice Formation contribute. These processes were the primary contributors to sea-Ice growth and characteristics only where the snow accumulation was large. In areas of low snow accumulation, there was no surface growth. Superimposed Ice Formation on sea Ice in Antarctica has not been reported previously. Evidence for snow cover melting, which is a prerequisite for superimposed Ice Formation, was also found.
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SEA-Ice Formation AND WATER STRUCTURES IN COASTAL POLYNYAS OFF LUTZOW-HOLM BAY AND BREID BAY
The Institute of Low Temperature Science Hokkaido University, 1994Co-Authors: ウシオ シュウキ, Kay I Ohshima, タキザワ タカトシ, カワムラ トシユキ, Shuki Ushio, Takatoshi Takizawa, Toshiyuki KawamuraAbstract:In a coastal region where strong offshore winds and currents prevail, newly-formed sea Ice is removed as quickly as it forms. Consequently, the open water areas are maintained for a long period of time, despite considerable Ice production. Such open waters, or coastal polynyas, release latent heat of fusion of Ice and moisture from the ocean to the atmosphere. High-salinity brine is also excluded to the ocean by sea-Ice Formation. The polynyas may have great influence on the atmosphere-ocean interaction. Satellite images have suggested the presence of winter coastal polynyas between fast Ice (or Ice shelf) and pack Ice regions off Lutzow-Holm Bay and Breid Bay, Antarctica. In 1990-1992,oceanographic observations were intensively conducted by the 31st and 32nd Japanese Antarctic Research Expeditions to understand sea-Ice and oceanic processes in the polynya off Lutzow-Holm Bay. Under windy conditions, aircraft observations revealed many new-Ice streaks formed approximately parallel to the wind direction and generation of frost smoke from the open water. Water temperature profiles in the polynya were obtained by using aircraft-deployed expendable bathythermographs (AXBT) with a depth capability of 460m. Based on the temperature data, it is estimated that the thickness of the convective-mixed layer with its freezing point is 350-450m. The mixed layer has a tendency to deepen in winter. According to the austral summer oceanographic data acquired on board the Icebreakers FUJI and SHIRASE, winter convective-mixed layers remain cold and oxygen-rich in the polynya regions. These mixed layers were evidently thicker than those in pack Ice regions. Such water structures were also formed in the Breid Bay polynya. The thick convective-mixed layer is considered to reflect the processes of vigorous sea-Ice production and the resultant convective mixing in the open polynyas