|TSM/TDM Science Team Meeting 2016|
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|TanDEM-X Science Service System|
|Title||High Spatio-temporal Resolution Surface Change of Major Glaciers From TerraSAR-X|
|Investigator||Braun, Alexander - Queens University, Geological Sciences and Geological Engineering|
|Summary||Recent studies show increasing evidence for continued acceleration of ice mass loss of Greenlandís ice sheet and particularly its outlet glaciers under a scenario of global warming. This corresponds with an increasing contribution to global sea level rise. However, predictions into the future are difficult as we do not know if or when a steady state will be reached (Shepard et al., 2012). The unprecedented availability of dedicated polar satellite missions has led to mass loss estimates which reasonably agree among sensors, but their representativeness is hindered by mostly reflecting larger scale processes of the ice sheet. The periphery is not well observed by satellite gravimetry or radar altimetry, but by TerraSAR-X. However, outlet glaciers show the largest ice velocities with significant variability on very broad time scales ranging from hours to seasonal. The governing mechanisms include ocean forcing, melt water duration and rates, drainage system geometry and percolation rates as well as climate variability, to name a few. |
The objective of the proposed study is to generate high spatio-temporal resolution surface change models of outlet glaciers, specifically, Jakobshavn Isbrae, Greenland, (one of the fastest thinning and retreating glaciers) and Hubbard Glacier, Alaska (a large tidewater glacier associated with advancing and thickening). In addition, we will target selected glaciers including Peterman Glacier, Greenland; Kangerdlugssuaq Glacier, Greenland; Lhagu Glacier, Tibet; Puncak Jaya/Carstensz Glacier, New Guinea. Herein, a surface model is a Digital Elevation Model (DEM) of the glacier with glaciological and climate attributes, including temperature, albedo, surface type (snow, ice, firn, water) etc. The targeted spatial scale is ~10 m, the temporal scale is down to 1 day. At the end of the project, a 12 year time series (start 2003 (ICESat), 2007 (TSX), end 2015) of surface models will be available. Ice velocities of outlet glaciers vary on multiple temporal scales, hours to days corresponds to melt water injection cycles into the drainage system, seasonal variability is controlled by climate and initial terminus retreat, ocean forcing can have both episodic and long-term impact on calving, meltwater discharge and heat transfer. We propose to fill the observation gap at time scales of days to weeks, which is often overlooked by space geodetic observations.
We will achieve the objectives by fusing a multitude of satellite and airborne observations to generate surface models and 3-D ice velocities which will be assimilated into numerical surface mass-balance and discharge models. TerraSAR-X InSAR will play a critical role in this development in that we propose InSAR at 11-day baselines and Multi-aperture Interferometry to estimate surface velocities. By having a time series of surface models, the spatio-temporal change can be validated between observations and model output. This will greatly enhance the quality of the model parameters and ultimately lead to better model predictions.
This project will directly contribute to generating long-term integrated records of polar change, it will target spatio-temporal scales which have not been addressed extensively by satellite observations, despite their significant impact on the ice sheet mass balance. Deliverables will include dynamic DEMs of the selected glaciers as well as mass balance estimates. We request all StripMap SSC data for all targeted glaciers available in the archive. The team will seek funding for this project through the NASA Cryospheric Program with a proposal due date of Feb 15, 2013.
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