Session time: 16 May 2018 @ 6:55 - 8:40 GMT
Session Chair: Vikram Goel, University of Oslo, Norway/NCAOR, Goa, India
Technical Support: Ilias Bougoudis, Institute of Environmental Physics, University of Bremen, Germany
07:00 - 07:15 GMT: Interannual sub-mesoscale mixing processes at the subsurface layer on a sill Fjord: The Ilulissat case, Greenland
Jhon F. Mojica1, Georges Djoumna2, Diana Francis1, David M. Holland1-3
1 Center for global Sea Level Change, NYUAD, Abu Dhabi, UAE
2 Environmental and Geophysical Fluid Dynamics, University of Waterloo, Ontario, Canada
3 Courant Institute of Mathematical Science, NYUNY, New York, USA
Type: Oral Presentation
Abstract: In the Ilulissat Ice Fjord, mixing processes promote an upward transport of diapycnal fluxes of heat and salt from the subsurface to the surface mixing layer. Here we estimate the diapycnal mixing rates from a multi-year oceanographic data from 2009-2013, to map the temporal variations of vertical mixing inside the fjord. By applying fine-scale parametrizations from density inversion methods (Thorpe approach), the mixing rates suggest enhanced mixing in the deep water over the sill depth inside the fjord, reaching a diapycnal diffusivity value of 1× 10-3 W kg-1. We found highest mixing rates in 2013, due to the melting conditions from the glacier and icebergs that perturb the internal water structure. The dataset revealed evidence of thermohaline staircases generated by the double-diﬀusion convection produced by salt fingering. Our results give insight on how the intrusion of polar waters into the Ilullissat Ice Fjord as well as heat transport and double-diffusion convection can affect the Jakobshavn Isbræ Glacier stability.
Sagar F. Wankhede, Shridhar D. Jawak, Alvarinho J. Luis
Mangalore University, Karnataka, India; Polar Remote Sensing Section, Polar Sciences Group, Earth System Science Organization (ESSO), National Centre for Antarctic and Ocean Research (NCAOR)
Type: Oral Presentation
Abstract: The study of glacier facies provides an opportunity to utilize these facies as indicators of climate change. Mass balance studies can be performed using glacier facies as proxies. The first essential step for such studies is the accurate extraction of glacier facies. Very high-resolution sensors are well equipped for the mapping and extraction of available facies. Therefore, this study utilizes WorldView-2 (WV-2) data to map and classify the available glacier facies on the Samudra Tapu glacier, Himalayas. Image classification through band ratioing and supervised classification techniques were the conventional methods used for mapping facies in the past. However, owing to the unique bands in the multispectral range of WV-2, this study has classified the available facies through the development of customized spectral index ratios (SIRs) in an object-oriented domain. Five supervised classifiers were then used to compare the classification accuracies. Error matrices were utilized to determine the accuracy achieved for each classification scheme. The object oriented approach attained an overall accuracy of 97.14% (κ=0.96) and the highest overall accuracy among the pixel-based classification methods is 74.28% (κ=0.70). The present results clearly show that the object-based method achieved greater accuracy than the pixel based methods. Future studies must examine the robustness and accuracy of the customized SIRs and develop more sensor-specific as well as transferable indices.
07:30 - 07:45 GMT: Comparing various remote sensing techniques for deriving glacier velocity; a case study of Polar Record Glacier, East Antarctica
Shubhang, Shridhar D. Jawak, Alvarinho J. Luis
Centre for Land Resource Management, Central University of Jharkhand, Ranchi, India; Polar Remote Sensing Section, Polar Sciences Group, Earth System Science Organization (ESSO), National Centre for Antarctic and Ocean Research (NCAOR), India
Type: Oral Presentation
Abstract: Polar glaciers play an important role in controlling the regional and global climate as well as global sea level changes. Different glacier parameters affect the changes in the glacier among which glacier velocity plays a key role in the glacier dynamics studies. Several image matching techniques have been used from the advent of remote sensing for displacement mapping. The current study is centred on estimating the precise velocity of the Polar Record Glacier, east Antarctica using optical remote sensing data. The study also focuses on comparing different tools to estimate accurate velocity in glaciers. The study was first conducted on a test area using four different tools for velocity estimation viz. COSI-Corr in ENVI, ImGRAFT in MATLAB, IMCORR feature tracking in SAGA-GIS and CIAS image correlation software in IDL. After evaluation of the tools, COSI-Corr outperformed the other three tools used for velocity estimation. COSI-Corr rendered fine resolution velocity with both magnitude and directions, whereas IMGRAFT provided the speed of the glaciers without the directions. IMCORR gave good results with magnitude and directions of glacier velocity but magnitude was obtained at coarser resolution. Velocity results from CIAS were obtained with both magnitude and direction but the outputs were present as bundled velocity. Due to the finer resolution and direction of obtained velocity, COSI-Corr was preferred for further studies to estimate velocity of Polar Record Glacier.
07:45 - 08:00 GMT: Mass balance and associated fresh water flux in Kongsfjord basin, northwest Svalbard
Norwegian Polar Institute, University of Oslo, Norway
Type: Oral Presentation
Abstract: In recent warming climate glaciers and ice caps are the major contributors to sea level rise. They are very susceptible to changing climate, and investigating long-term mass balance of glaciers is essential. Apart from sea-level rise, fresh water from glaciers modulates ocean circulation and biological activities. Arctic region is experiencing greater warming than rest of the world. In northwest Svalbard, Kongsfjord basin is a hotspot for interdisciplinary studies many of which addressing the significance of fresh water from glaciers and seasonal snow.
We use an energy balance model coupled with subsurface snow model to simulate long-term (1980-2016) mass balance evolution of glacierized area and season snow development of non-glacierized area of Kongsfjord basin. Meteorological data from the nearby station at Ny-Ålesund is used for climate forcing in the model domain, with mass balance data at four glaciers in the Kongsfjord watershed used to calibrate model parameters. The model is forced with downscaled ERA-Interim precipitation. Area-average mass balance of entire glacierized area in positive (+0.23 m w.e.a-1), however, there is spatial variability in mass balance where north region show more positive mass balance than south and east. We found significant negative trend in mass balance for all the region over the period 1980-2006.
We investigated the steady state subglacial hydrology of major area of tidewater glaciers and supraglacial hydrology of land-terminating glaciers, and implemented a simple runoff routing model to quantify discharge at the glacier outlet points. Observational plume and discharge data is used for model evaluation.
08:00 - 08:10 GMT: POPs to Poles; transportation of Persistent Organic Pollutants (POPs) to the Polar regions
Mangalore University, India
Type: Innovative Communication
Abstract: Persistent Organic Pollutants (POPs) are a group of chemical compounds which have no natural sources and produced in the environment only by the anthropogenic activities such as (1) use of pesticides, (2) emission and use of industrial and technical chemicals and (3) by-products of high-temperature processes. POPs can persist in the environment for several years and can circulate and reach to the Polar Regions via a process called the “grasshopper effect”. In this presentation, I will innovatively communicate the transport of POPs to poles using a creative cartoon designed by myself. I would explain about the phenomenon of global distillation or grasshopper effect and how it helped to POPs to reach to the most pristine place on the Earth ─ Polar regions, where they have never been used or discharged. This presentation is targeted to explain the complex environmental process to the general audience using a simple cartoon which can be used as a model in wider scientific community focusing on long-range transportation of POPs to the polar regions.
Nicole Biebow, Veronica Willmott
Alfred Wegener Institut Helmholtz Centre for Polar and Marine Research, Germany