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Greenland

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  • The Greenland Flow Distortion EXperiment, based in Keflavik, Iceland, took place during February 2007. Its aim was to improve the understanding and ability to predict interactions between the atmospheric circulation and the topography of Greenland, both locally and downstream over Western Europe. Hitherto rare in situ observations of high-impact weather systems and their associated air-sea fluxes in the coastal seas of Greenland, were obtained and will be used to improve the numerical modelling and prediction of these weather systems, and thus improve the quality of the atmospheric forcing fields that are essential for accurate atmosphere-ocean coupling and the thermohaline circulation. These measurements will also be used to improve the numerical modelling and prediction of high-impact weather systems over Europe through the use of targeted observations upstream in sensitive areas of the flow. This project investigates the role of Greenland in defining the structure and the predictability of both local and downstream weather systems, through a programme of aircraft-based observation and numerical modelling. The Greenland Flow Distortion Experiment (GFDex) will provide some of the first detailed in situ observations of the intense atmospheric forcing events that are thought to be important in modifying the ocean in this area (but are presently poorly understood): namely tip jets, barrier winds and mesoscale cyclones. Tip jets form at the southern tip of Greenland, at Cape Farewell, through the forcing of flow over and around the topography. Barrier winds occur when the large-scale flow is piled up against the southeast coast of Greenland, forcing winds parallel to the coast. While located off this southeast coast is an area of frequent mesoscale cyclogenesis. GFDex will also investigate Greenlands role in atmospheric flow predictability by carrying out upstream observations that are targeted at investigating the sensitivity of the downstream flow to the details of the upstream flow and at improving subsequent forecasts over Europe. Greenlands flow distortion can trigger large-scale atmospheric Rossby waves which influence weather systems thousands of kilometres away and several days later. These waves are by nature predictable, so by adapting our observing strategy to target specific areas, improvements in subsequent forecasts over the United Kingdom are possible. Numerical modelling experiments after the field campaign will be used to assess any improvements from the additional targeted observations. While further numerical modelling studies of the high impact local weather systems will be evaluated and refined using the aircraft-based observations. This will increase our understanding of these systems and, through comparisons with other observations and data sets, provide accurate fields of air-sea heat and moisture fluxes for driving ocean and climate models.

  • This dataset has been produced as part of the Theme 5 (Cryosphere and Polar Oceans) in the National Centre for Earth Observation which aims to use new EO data to quantify changes in the mass balance of the cryosphere and to develop new models to represent the relevant processes in coupled climate prediction models. This dataset holds timeseries of Greenland glacier calving front fluctuations as maps and backscatter intensity images for the period March-July 2011. The dataset consists of 38 SAR backscatter images acquired every 3 days between the 12th March and 1st July 2011 during the ERS-2 3-day campaign. The backscatter data were transformed to map coordinates using the GLAS/ICESat 1 km Laser Altimetry Digital Elevation Model of Greenland which is provided at Polar Stereographic grids (DiMarzio, J., Brenner, A., Schutz, R., Schuman, A. & Zwally, H.J. (2007): GLAS/ICESat 1 km laser altimetri digital elevation model of Greenland. Boulder, Colorado USA: National Snow and Ice Data Centre. Digital media).

  • The Greenland Ice Sheet CCI project aims to maximize the impact of ESA satellite data on climate research, by analysing data from ESA Earth Observation missions such as ERS, Envisat, CryoSat, GRACE and the new Sentinel series of satellites. Over the last decade, the Greenland Ice Sheet has shown rapid change, characterized by rapid thinning along the margins, accelerating outlet glaciers, and overall increasing mass loss. The state of the Greenland Ice Sheet is of global importance, and has consequently been included in the ESA CCI Programme as a monitored Essential Climate Variable (ECV). The project is producing data products of the following five parameters, which are important in characterizing the Greenland Ice Sheet as an Essential Climate Variable: Surface Elevation Change (SEC) gridded data from radar altimetry; Ice Velocity (IV) gridded data from synthetic aperture radar interferometry and feature tracking; Calving Front Location (CFL) time series of marine-terminating glaciers; Grounding Line Location (GLL) time series of marine-terminating glaciers; Gravimetry Mass Balance (GMB) maps and time series.

  • This dataset contains a time series of ice velocities for the Upernavik glacier in Greenland between 1992 and 2010. This dataset has been produced by the ESA Greenland Ice Sheet Climate Change Initiative (CCI) project. This dataset consists of a time series of Ice velocity maps which have been generated from SAR data from the ERS-1 and ERS-2, ENVISAT and the ALOS satellites. The data are supplied on a 500m polar stereographic grid. The ice velocity product contain the horizontal components, vN and vE, of the total velocity vector, which is derived from radar measurements assuming surface parallel flow. The used digital elevation model of the surface is also supplied. The North and East velocities at any grid points are given in a local geographic north-east coordinates system (and not in the used grid map projection system).

  • This dataset has been produced as part of the Theme 5 (Cryosphere and Polar Oceans) in the National Centre for Earth Observation which aims to use new EO data to quantify changes in the mass balance of the cryosphere and to develop new models to represent the relevant processes in coupled climate prediction models. This dataset holds timeseries of Greenland glacier velocity fluctuations as maps for the period March-July 2011. The 37 velocity maps were derived from SAR data acquired during the 2011 ERS-2 3-day campaign. The velocity maps are 3-day velocity averages and are given in meters per year (m/y) (magnitude values). The name of the velocity files provides the start and end date of each 3-day period. The velocity fields were transformed to map coordinates using the GLAS/ICESat 1 km Laser Altimetry Digital Elevation Model of Greenland which is provided at Polar Stereographic grids (DiMarzio, J., Brenner, A., Schutz, R., Schuman, A. & Zwally, H.J. (2007)): GLAS/ICESat 1 km laser altimetri digital elevation model of Greenland. Boulder, Colorado USA: National Snow and Ice Data Centre. Digital media).

  • This dataset contains grounding lines for 5 North Greenland glaciers, derived from SAR Interferometery data from the ERS-1 and -2 satellites. Data was produced as part of the ESA Greenland Ice Sheets Climate Change Initiative (CCI) project by ENVEO, Austria. The grounding line separates the floating part of a glacier from the grounded part. Processes at the grounding lines of floating marine termini of glaciers and ice streams are important for understanding the response of the ice masses to changing boundary conditions and for establishing realistic scenarios for the response to climate change. The grounding line location product is derived from InSAR data by mapping the tidal flexure and is generated for a selection of the few glaciers in Greenland, which have a floating tongue. In general, the true location of the grounding line is unknown, and therefore validation is difficult for this product. Remote sensing observations do not provide direct measurement on the transition from floating to grounding ice (the grounding line). The satellite data deliver observations on ice surface features (e.g. tidal deformation by InSAR, spatial changes in texture and shading in optical images) that are indirect indicators for estimating the position of the grounding line. Due to the plasticity of ice these indicators spread out over a zone upstream and downstream of the grounding line, the tidal flexure zone (also called grounding zone).

  • A coastline of Kalaallit Nunaat/ Greenland covering all land and islands, produced in 2017 for the BAS map ''Greenland and the European Arctic''. The dataset was produced by extracting the land mask from the Greenland BedMachine dataset and manually editing anomalous data. Some missing islands were added and glacier fronts were updated using 2017 satellite imagery. The dataset can be used for cartography, analysis and as a mask, amongst other uses. At very large scales, the data will appear angular due to the nature of being extracted from a raster with 150 m cell size, but the dataset should be suitable for use at most scales and can be edited by the user to exclude very small islands if required. The projection of the dataset is WGS 84 NSIDC Sea Ice Polar Stereographic North, EPSG 3413. The dataset does not promise to cover every island and coastlines were digitised using the data creator''s interpretation of the landforms from the images.

  • From May 2009 to May 2013, seven dual-frequency GPS receivers were deployed along a 120 km-long transect in the south-west of the Greenland Ice Sheet. Two additional dual-frequency GPS receivers were deployed perpendicular to longitudinal ice flow at ~14 km inland: one 5 km distant from June 2011 to May 2013, and another 2.5 km distance from May 2012 to May 2013. Each receiver recorded position observations every 10 seconds or 30 seconds (depending on configuration), enabling resolution of horizontal and vertical ice motion. Sites were powered by solar panels and operated 24 hours a day during summer but shut down in the autumn. Absolute ice displacements at each site were obtained for each summer and winter period in the absence of continuous measurements. Position measurements were kinematically corrected relative to an off-ice base station using TRACK (Chen, 1999). Daily velocities were then obtained by differencing across 24-hour periods, whilst continuous velocities were obtained through application of a sliding 6-hour differencing window. At each GPS site we also measured (1) the near-surface air temperature every 15 minutes year-round, (2) net seasonal ablation using ablation stakes, and (3) at several selected sites melt rates using sonic ranging sensors. This version 2 of the dataset updates the previously 2-day temporal resolution of the ice motion records to 1-day resolution. In other respects the dataset has not changed. Funded by NERC, the Carnegie Trust for the Universities of Scotland and The University of Edinburgh. Relevant grants: NE/F021399/1, NE/H024964/1 Studentships: NE/I52830X/1, NE/J500021/1, NE/H526794/1

  • From May 2009 to May 2013, seven dual-frequency GPS receivers were deployed along a 120 km-long transect in the south-west of the Greenland Ice Sheet. Two additional dual-frequency GPS receivers were deployed perpendicular to longitudinal ice flow at ~14 km inland: one 5 km distant from June 2011 to May 2013, and another 2.5 km distance from May 2012 to May 2013. Each receiver recorded position observations every 10 seconds or 30 seconds (depending on configuration), enabling resolution of horizontal and vertical ice motion. Sites were powered by solar panels and operated 24 hours a day during summer but shut down in the autumn. Absolute ice displacements at each site were obtained for each summer and winter period in the absence of continuous measurements. Position measurements were kinematically corrected relative to an off-ice base station using TRACK (Chen, 1999). Daily velocities were then obtained by differencing across 24-hour periods, whilst continuous velocities were obtained through application of a sliding 6-hour differencing window. At each GPS site we also measured (1) the near-surface air temperature every 15 minutes year-round, (2) net seasonal ablation using ablation stakes, and (3) at several selected sites melt rates using sonic ranging sensors. Funded by NERC, the Carnegie Trust for the Universities of Scotland and The University of Edinburgh. Relevant grants: NE/F021399/1, NE/H024964/1 Studentships: NE/I52830X/1, NE/J500021/1, NE/H526794/1

  • Metrics of dark ice extent and duration, and snowline retreat estimates, for the south-west ablation zone of the Greenland Ice Sheet, derived from MODIS satellite imagery. These metrics are provided on a ~613 m grid at annual resolution and cover the melt season, defined as June-July-August each year. All scripts used to generate the metrics are also provided, as well as the scripts which generate the plots found in the referenced publication. Funding was provided by the NERC grant NE/M021025/1.