Wael Abdel Jaber

Surface elevation changes of glaciers derived from SRTM and TanDEM-X DEM differences

We compare ice elevation from TanDEM-X DEMs of 2011/2012 and SRTM DEM of 2000 over the Southern Patagonia Icefield (SPI) in order to quantify the volume loss of the icefield over the last decade. The map of elevation change rate is discussed. Detailed results are shown for two glaciers: Jorge Montt and Pio XI, exhibiting opposite trends in elevation and front position.

Dynamics of fast glaciers in the Patagonia Icefields derived from TerraSAR-X and TanDEM-X data

Observations of ice flow velocity with TerraSAR-X were carried out over main outlet glaciers of the Southern Patagonia Icefield (SPI) since 2008 by means of amplitude correlation technique. Velocity data are required to estimate the ice export due to calving. Furthermore we compare ice elevation from a TanDEM-X DEM of 2011 and from an SRTM DEM of 2000 in order to quantify the volume loss of these glaciers over the last decade. Results are shown for three glaciers of the central section of SPI, exhibiting distinct differences in the observed trends for surface topography and ice velocity.

TerraSAR-X observations over the antarctic ice sheet

An incoherent correlation approach is used to derive ice motion fields for outlet glaciers through the Transantarctic Mountains, Antarctica. High-resolution repeat-pass, left-looking-mode TerraSAR-X data from 2009 were analyzed. Detailed ice velocity patterns on the Nimrod glacier basin and Starshot glacier are presented.

Glacier dynamics of the Northern Patagonia Icefield derived from SRTM, TanDEM-X and TerraSAR-X data

We compare ice elevation from a TanDEM-X DEM of September 2013 and the SRTM DEM of 2000 over the main glaciers of the Northern Patagonia Icefield (NPI) in order to quantify ice change rates over the last 13 years. The applied procedure and the obtained results are discussed. In order to have a more comprehensive picture of ice dynamics for this region, ice flow velocity maps for the S. Quintin and S. Rafael glaciers are obtained from feature tracking applied to TerraSAR-X high resolution repeat pass images.

TanDEM-X for mass balance of glaciers and subglacial volcanic activities

The TanDEM-X satellite mission through its bistatic formation provides high horizontal and vertical resolution topographic data. Multi temporal TanDEM-X acquisitions allow short term analysis of variations of the earth surface elevation which in turn can be converted to volume changes. We are investigating the capabilities of the TanDEM-X data to detect and map short term changes at glacier surfaces in two different situations. One study case is Jorge Montt outlet glacier of the South Patagonia Icefield known for its accelerated mass depletion and front retreat. The second example is located on the Vatnajökull Ice Cap in Iceland and is related to the activity of the Bárǒarbunga volcanic system in summer 2014 as a consequence of climate driven depletion as well as due to volcanic activities below the ice surface.

Terrasar-X observations of antarctic outlet glaciers in the ross sea sector

We discuss TerraSAR-X observations of two Transantarctic Mountain outlet glaciers, Nimrod and Byrd. High resolution TerraSAR-X data acquired over the area in late 2009 and late 2010 using left looking mode were processed to generate detailed 2D ice velocity maps by speckle tracking. The patterns of ice flow from East Antarctica to Ross Ice Shelf are analyzed and compared by means of longitudinal and transverse transects. Detailed knowledge about surface velocity is crucial for estimating the magnitude of ice flux and understanding the dynamics East Antarctica fast glaciers that discharge into the Ross Ice Shelf.

TerraSAR-X and TanDEM-X observations of the Recovery Glacier system, Antarctica

We analyzed ice velocities and surface elevations of the Recovery Glacier system in Antarctica derived from TerraSAR-X and TanDEM-X data. Our high resolution TerraSAR-X velocity mosaic was generated with speckle tracking applied to data acquired in 2012 and 2013 using the left looking mode. Flow variations along the main trunk of Recovery is discussed. In addition we processed 5 strips of TanDEM-X data from 2013 into calibrated DEMs. The Operation Icebridge ATM profiles crossing the main trunk of Recovery and the TanDEM-X elevation show very similar patterns confirming the capability of the SAR DEMs to provide spatially detailed topography of Antarctica.

IMaging geodesy with TerraSAR-X

We report on a method and experiments to achieve about 3 centimeters pixel location accuracy of TerraSAR-X SAR images. The method is based on atmospheric refraction corrections, Earth tide compensation and image correlation or the use of corner reflectors. Our method does not exploit the SAR phase and is therefore not subject to phase unwrapping problems or unknown phase offsets.

The recovery ice stream: Synergy of satellite and airborne remote sensing for flow dynamics

The Recovery Ice Stream with its large catchment basin plays an important role in discharging ice from East Antarctica into the Weddell Sea through the Filchner Ice Shelf. Its scientific interest is also linked to the discovery that the ice flow is influenced by the discharge of several subglacial lakes, which could trigger a faster flow due to reduced friction on the glacier bed. We analyzed surface elevations of the Recovery Glacier system in Antarctica derived from time series of TanDEM-X data with focus on location of subglacial lakes. The absolute calibration of the TanDEM-X DEMs was performed using airborne laser altimetry datasets from NASAs Operation Icebridge ATM and AWIs Polar 6. In addition the grounding line position for the neighbouring Slessor, Bailey and Recovery glaciers was estimated through DInSAR with TerraSAR-X data acquired in 2014 and 2015.