Registration link to attend SESSION 3: https://attendee.gotowebinar.com/register/8035206061385125889
Note: Please register as early as possible but no later than 30 min before the session as the attendance link will be sent to you via email.
OCEANOGRAPHY / SEA-ICE
Chair: Yulia Zaika
Siva Prasad, Igor Zakharov , Pradeep Bobby , Peter McGuire, Memorial University of Newfoundland, Canada
Abstract: Data assimilated sea ice model for the Baffin Bay and Labrador region - The Los Alamos sea ice model (CICE) was implemented on a high resolution regional scale. North Americal Regional Reeanalysis (NARR) data were used for atmospheric forcing as well as climoatological ocean forcing derived from sources such as NCEP Climate Forecast System Reanalysis CFSR (currents), SST (NCEP-High Resolution) and SSS derived from World Ocean Atlas 2013 (WOA 2013). A density based criteria of 0.2 kg/m^3 with corrections for bathymetry was used to optimise the mixed layer depth from WOA 2013 data with assumption of zero mixed layer heat flux. Assimilation of SST from AMSRE-AVHRR and OSI-SAF (Special Senson Microwave Imager/Sounder (SSMIS)) product using a Combined Optimal Interpolation scheme shows improvement in the assimilated sea ice concentration and other parameters. The results were validated with sea ice concentration derived from AMSRE and ice thickness derived from soil Moisture and Ocean Salinity - Microwave Imaging Radiometer with Aperture Synthesis (SMOS-MIRAS). A validation of the ice thickness and freeboard was performed with measurements from Crysat-2. A robust statistical analysis of other parameters based on observation is a future work.
Ben Butler, Stathys Papadimitriou, Hilary Kennedy, School of Ocean Sciences, Bangor University, UK
Abstract: The sea ice cover of high latitude oceans contains concentrated brines which are the site of in-situ chemical and biological reactions. The brines become supersaturated with respect to mirabilite (Na 2 SO 4 ·10H 2 O) below –6.4 °C, and the associated removal of Na + and SO 4 2- from the brine results in considerable non-conservative changes to its composition. The changes are reflected in the brine salinity, which is a fundamental physico-chemical parameter in the sea ice brine system. Here, measurements of electrical conductivity and brine composition in synthetic sea ice brines between –1.8 and –20.6 °C, obtained during a comprehensive investigation of the brine–mirabilite equilibrium at below-zero temperatures, are combined with modelled estimates to assess the behaviour of the absolute (S A ) and practical (S P ) salinities of sea ice brines. Results display substantial divergence of S P from S A below –6.4 °C, which approaches a 7.2% difference with decreasing temperature. This is shown to create inaccuracies when S P is assumed to be equivalent to S A , firstly by misrepresenting the conditions inhabited by sea ice biota, whilst also creating errors in the calculation of physical sea ice parameters. Our measured and modelled data are used to refine the S A – T relationship for sea ice brines, implicit of mirabilite precipitation, which is crucial in estimating brine properties in absence of salinity data. Furthermore, because S P is the parameter measured in field studies, we provide an S P – T relationship for sea ice brines to –22.8 °C, which also describes available S P – T data from sea ice brines in the Southern Ocean, demonstrating the importance of the mirabilite–brine equilibrium in natural sea ice. Finally, we propose a conversion factor for the estimation of S A from S P measurement in sea ice brines. This work ultimately highlights careful consideration of salinity concepts when applied to the sea ice system.
Anna Raczkowska1,2, Piotr Kowalczuk1, Slawomir Sagan1, Monika Zablocka1
1 Institute of Oceanology Polish Academy of Sciences, Powstancow Warszawy 55, 81-712 Sopot
2 Centre for Polar Studies, Leading National Research Centre, 60 Bedzinska Street, 41-200 Sosnowiec, Poland
Abstract: Growth in average annual temperatures as well as shrinking and thinning ice cover in the Arctic Ocean measured over past three decades has led to changes in thermodynamic equilibrium in this region. One of the mechanisms regulating the heat accumulation in the Arctic is based on relation between albedo and physical characteristics of sea ice cover. Coloured Dissolved Organic Matter (CDOM) is a part of the Dissolved Organic Matter which absorbs the light in the range of visible light and ultraviolet. CDOM is present in all natural waters. CDOM is a key factor responsible for the vertical entrapment of heat and light availability for primary production in the Arctic Ocean. Recent studies has shown that about 50–60% more heat deposition is gathered in the upper meters of the East Greenland Current waters (western side of Fram Strait) as a consequence of high concentrations of CDOM in comparison to clearest natural waters (Granskog at. all, 2015). The heat absorbed by CDOM contributes to acceleration of sea-ice melt process and albedo changes in Arctic’s physical system.
The aim of this study is to characterize optical properties of CDOM in Nordic Seas. The experimental material has been collected during three summer seasons (2013-2015) onboard Polish r/v Oceania and Norwegian r/v Lance in the western and northern Spitsbergen Shelf, Norwegian Sea, Barents Sea as well as in the Fram Strait. Arctic optical measurements methods, spatial distribution of CDOM, fluorescence as indicator of composition and sources of CDOM will be presented.
15:15 - 15:30 GMT: Satellite remote sensing of mineral suspended matter in Hornsund fjord (Svalbard).
Katarzyna Dragańska, Institute of Oceanology Polish Academy of Science, Poland
Abstract: One of the most spectacular effects of climate change is intense recession and melting glaciers observed in the polar regions. The recession of glaciers is accompanied by intensification of melt water runoff and mineral particles supply. The direction and intensity of Svalbard glaciers change is therefore an indicator of climate change taking place both in the Arctic and globally. Distribution of mineral suspended matter derived from melting glaciers is an important factor for marine ecosystem. Amount and spread of suspended matter also affects the light availability in water columns, which influences on organisms living on the bottom. The scale and intensity of these processes depend on the glacier activity.
In high latitudes, ice melting optically influences the satellite data. In this study, we assessed suspended sediment in one of Spitsbergen’s fjord - Hornsund using high resolution satellite data ( Landsat-8 OLI). To estimate suspended sediment concentrations, various regression models were tested with different band ratio. Regression models shown high correlation in spite of the temporal difference between satellite data and in-situ data. Model-derived distribution of ocean color product by OLI showed possibility that a fjord and a coastal area in polar region can be monitored with high resolution satellite data. It has been shown that in order to determine the concentration of the suspened matter from the satellite images is necessary to take into account the differences in the its composition and create a separate algorithms for significantly different glacier bays. Result of this study will be used to high resolution monitoring mineral suspended sediment from glacier and its influences on the marine ecosystem change.
GEOLOGICAL / ENVIRONMENTAL / TERRESTRIAL / CRYOSPHERIC ENVIRONMENTS
15:30 - 15:45 GMT: Accelerated ice flow enhance basal till deformation and flutes formation, Nordenskiöldbreen foreland, Svalbard
Aleksander Dominiczak, Marek Ewewrtowski, Adam Mickiewicz University in Poznan
Abstract: Despite significant progress in the field of glacial geomorphology and geology still many questions remain unanswered and previously established theories requires verification. Processes leading to formation of fluted moraine still raises doubts. Research area, Nordenskiöldbreen foreland, was formerly subject of detailed study concerning flutes performed by Boulton (1976). For a better understanding of processes leading to formation of marginal zone we have focused on geomorphological and sedimentological analysis, especially on sediments-landform assemblages, additionally we attempted to reconstruct paleo ice flow directions. We were also trying to verify hypothesis about the creation of fluted moraine in effect of glacier surge. Landform mapping highlights specific location of flutes, which favors topographically induced fast flow. Ice flow direction were measured using flutes and striation on flat rock surfaces, and shows consistent flow from east to west. RA/C40 analysis highlights subglacial origin of all analyzed bedforms including flutes, moraine ridge, till plain patches and insets on roches mutonnées and outwash valleys (reworked till). Grain size analysis of fraction below 2mm shows high uniformity of distribution for flutes what indicates that sediments in flutes are very well mixed, most likely as a result of intense deformation. All that leads to statement that accelerated ice flow is really important factor for both basal till deformation and flutes formation.
Adelina Geyer, Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Group of Volcanology, SIMGEO (UB-CSIC), Lluís Solé i Sabarís s/n, 08028 Barcelona, Spa
Abstract: Deception Island is the most active volcano in the South Shetland Islands and has been the scene of more than twenty identified eruptions over the past two centuries. In this contribution we present the first comprehensive long-term volcanic hazard assessment for this volcanic island. The research is based on the use of probabilistic methods and statistical techniques to estimate volcanic susceptibility, eruption recurrence and the most likely future eruptive scenarios. We perform a statistical analysis of the time series of past eruptions and the spatial extent of their products, including lava flows, fallout, pyroclastic density currents and lahars. The Bayesian event tree statistical method HASSET is applied to calculate eruption recurrence, while the QVAST tool is used in an analysis of past activity to calculate the possibility that new vents will open (volcanic susceptibility). On the basis of these calculations, we identify a number of significant scenarios using the GIS-based VORIS 2.0.1 and LAHARZ software and evaluate the potential extent of the main volcanic hazards to be expected on the island. This study represents a step forward in the evaluation of volcanic hazard on Deception Island and the results obtained are potentially useful for long-term emergency planning.
16:00 - 16:15 GMT: The influence of the natural environment on habitat preference for lichens in Western Dronning Maud Land, Antarctica.
Gabrielle Ayres, Rhodes University, South Africa
Abstract: The biogeography of lichens in part of Western Dronning Maud Antarctica was used to elucidate Biology-Gemorphological interactions. Two continental nunataks, Vesleskarvet and Robertskollen, were selected to characterise climatic, topographical and geomorphological variables and their impact on lichen colonisation at a fine resolution. Small-scale (sub-metre) topographical features were identified and classified together with the specific lichen species that colonised them. The methodology employed included the use of structure from motion techniques to create three-dimensional models for the display of the habitat preference on specific clasts. Small-scale topographical features provide sheltered locations that serve as microhabitats that support lichen colonisation. Moist and sheltered microhabitats are the most suitable for colonisation, with habitat preferences being noted to be specific to a particular lichen species. The predominant species, Usnea sphacelata and Umbilicaria decussata, colonised sheltered depressions in the topography, specifically beneath overhangs. Finer topographical features such as cracks, pitting and tafoni were found to be colonised by other lichen species. This study shows preferential colonisation strategies of lichens in Antarctica and, thus, these habitats are a suitable proxy for monitoring environmental changes.
Chair: Yulia Zaika