Interferometric Evaluation of Glacier Rheology and Alterations (INTEGRAL)

Software library that provides Application Program Interfaces to read Cryosat l1B and GDR (Geophysical Data Record) products have been developed. The library contains C functions and supporting header files to read Cryosat Level 2 formatted files fromdisk into memory. The provided functions allow the user to create programs that read whole input files into memory or pickout specific records to read. Also included are a number of IDL routines to read products. The library is issued on CD and a user guide is also available.

The general objective of the Integral initiative was to promote an advanced observation technology for the unsupervised detection, precise measurement and variational analysis of ice motion / deformation on large European glaciers based on the complementary use of radar interferometry and interferometric altimetry, and to support natural exploration, social-economic activities and subsequent surveys in the nival environment with equivalent rheological1 models and appropriate information on the glacier regime in the form of new value-added INSAR products. The polar idea was to enhance the detailedness, accuracy, integrity and versatility of glacier interferometric models yet without involving complex process artifices and to demonstrate new utilities of radar interferometry to operational users working with radar and lidar data from post-operational, operational and upcoming systems such as E-SAR, ERS, SRTM, Envisat, Radarsat, Icesat and Cryosat. The Integral project was, thus, focused on methodological aspects and empirical issues of glacier interferometry, and major attention was paid to: - design of enhanced algorithms and program tools for processing and fusing spaceborne SAR interferograms with altimetry data, both radar and lidar, aimed at precise geocoding and upgrading the information content of glacier rheological models; - practical application of phase-gradient, feature tracking, transferential and combined interferometric techniques to the detection and interpretation of glacier activity, numerical modelling of the glacier regime, and assessment of main tendencies in the state of land ice resources in response to climate change; - production, demonstration and implementation of the series of interferometric 'snap-shots', full-value maps and value-added products showing the ice-surface velocity structure, glacier strain rate and fluctuations of the specific glacier mass balance. The Integral consortium achieved the following milestones. General concept for satellite interferometric monitoring of large glacial complexes Advanced observation technology of large glacial complexes using satellite interferometry and altimetry. The monitoring concept is based on a new remote sensing method involving the combination of satellite interferometry and altimetry (Insaral). Unique combination of technical parameters related with glacier monitoring is specified, argued and verified. Simulated Cryosat data for Norwegian and Svalbard glaciers Simulated Cryosat data for Austfonna, Kronebreen, Kongsvegen (all Svalbard) and Svartisen (northern Norway) data were created. This allows potential users of Cryosat 2 to examine in advance of whether this is a useful source of data for their work on these or similar glaciers. Several of the glaciers for which there are simulated data have significant topography and were not the prime focus of the mission requirements for Cryosat. One of the glaciers, Austfonna, is one of the largest ice masses in Europe (8000 square metres) and until recently, very little was known about it. Ice flux dataset for Austfonna, Svalbard Basin-wide statistics of ice volume flux from margin change and ice velocity for the Austfonna ice sheet in Svalbard have been calculated. Velocity data from INSAR, and ice thickness data collected by SPRI in 1983 and 1986 were used. These values are a major contribution in estimating changes in sea level to due to glacier and ice sheet melting. Comprehensive set of visualised Icesat - GLAS data for the Barents Sea Region Set of visualised tracks of Icesat - GLAS data taken over the Barents Sea Region in cold seasons, 2003 - 2005 (quality-controlled) representing contemporary heights of ice-coasts and main ice divides in the Novaya Zemlya, Svalbard and Franz Josef Land study areas. Enhanced methodology of (D)INSAR data processing Straightforward differential analysis of INSAR data using phase-gradient and transferential approaches providing new series of INSAR value-products such as topogram (phase-gradient image), fluxogram (differential phase-gradient image) and STRIP (strain rate image product). New approaches to Dinsar data processing mitigating some problems related to the operation of interferometric phase unwrapping and differential interferometry and a new set of robust algorithms for Dinsar data processing, which can be used in commercial software packages. Method for glacier motion estimation with satellite L-band SAR data A robust and direct estimation technique of glacier motion based on satellite L-band SAR data has been developed. With this method the registration offsets of two SAR images are used to estimate the displacement of glaciers. Offset-tracking is a welcome alternative to SAR interferometry when the latter is limited by rapid flow and large acquisition time intervals between the two SAR images. The innovative aspect is to use the L-band SAR data, for which experience is limited. The results obtained so far for Arctic glaciers using SAR data acquired by a satellite operated until 1998 (the Japanese Earth Resources Satellite JERS-1) are significant in expectation of data from the Palsar sensor onboard the Japanese Advanced Land Observing Satellite (ALOS) launched in early 2006. The estimated error of the JERS-1 offset tracking derived displacement is on the order of 20 m/year. Glacier motion monitoring using spaceborne SAR Retrieval of motion fields of glaciers and ice sheets using repeat pass imaging radar data. Optionally interferometric techniques or image correlation are applied. Application for studies of glacier dynamics and glacier-climate interaction. Application Program Interfaces to read Cryosat L1b and GDR data products Software library that provides Application Program Interfaces to read Cryosat l1B and GDR (Geophysical Data Record) products have been developed. The library contains C functions and supporting header files to read Cryosat Level 2 formatted files from disk into memory. The provided functions allow the user to create programs that read whole input files into memory or pickout specific records to read. Also included are a number of IDL routines to read products. The library is issued on CD and a user guide is also available. New software package for (D)INSAR and ALTI data processing New sequence of software blocks and functionalities for geometric processing of overlapping (multitemporal) interferometric models including joint processing of C- and L-band SAR interferograms and interferometric mapping of ice flow and glacier changes (freely accessible and applicable to the ERS-AMI, Envisat-ASAR, ALOS-Palsar and Terrasar data processing) realised in the form of licensed RSG software package, release 5.1, stand-alone version. Glacier mass-balance and runoff model The system for modelling glacier mass balance and runoff uses satellite-derived information in synergy with meteorological observations. Multispectral optical and synthetic aperture radar (SAR) satellite data are used to map the extent of glaciers, retrieve surface albedo, and monitor the temporal evolution of snow and ice areas. Surface motion of glaciers is derived from repeat pass SAR images by means of interferometric analysis. A conceptual, semi-distributed model is applied for calculating daily changes of glacier mass and runoff. For model input temperature and precipitation data from meteorological stations are extrapolated to DEM grids and integrated with satellite-based time series of snow and ice extent. The model was successfully applied to glaciers in the Alps and Norway. New knowledge on the present regime and changes of European tidewater glaciers Contemporary rates of ice loss processes in linear, areal, volumetric, and fluxometric terms were determined over Franz Josef Land, North Novaya Zemlya and Svalbard for the last decade and for the past 50 years. Several new geographic objects (capes, bays, islands) were discovered in the study areas due to the glacier retreat. New tendencies in the behaviour of large tidewater glaciers caused by climate changes and environmental forcing were revealed. Three years of glaciological data for Austfonna Three years (2004-2006) of mass balance, surface topography changes, ice surface velocities and meteorology data were obtained for Austfonna on Austlandet in Svalbard, the largest icecap in the European Arctic. Dataset of glacier surface velocities from satellite SAR data Glacier surface velocities from Svartisen,Unteraargletscher, Svalbard, Novaya Zemlya and Franz Josef Land were derived from satellite SAR data using interferometry and offset-tracking. Satellite SAR data were acquired between 1991 and 1998 from ERS-1, ERS-2 and JERS with acquisition time intervals between 1 and 44 days. Simultaneous measurements of surface and basal glacier velocities, and subglacial pressures Simultaneous measurements were made over a period of several days of glacier surface velocity and basal sliding, as well as the subglacial pressure under Engabreen, Svartisen in Northern Norway. The measurements were made using the Svartisen Subglacial Laboratory in order to gain access to the ice-rock interface. Earth pressure cells installed at this interface measured the basal pressure, and three GPS stations on the glacier within 1 km distance, measured the surface velocity. Measurements were made over a period of several days in April 2006. This gave a unique dataset that shows how these important glacier parameters are related. Methodology of glacier tachometric surveys in the field New, precise and simple 'touch-and-go' technique for measuring glacier (frontal) velocities using laser rangefinder and dGPS records of the fast-sea-ice translation. INSAR velocities of 9 test glaciers in the Höhe Tauern, Svalbard and Novaya Zemlya test sites were validated during the field surveys with the total duration of 2.5 weeks. Regional reference database Regard Regional glacial reference database Regard represents regime and changes of Arctic glaciers (Svalbard, Novaya Zemlya, Franz-Josef Land). This database contains: 1) regional cartographic reference base of the INTEGRAL / FAR Barents Sea region (maps and multimedia modules), 2) maps and other value-added products showing spatial and temporal changes of Arctic glaciers, 3) catalogue of tidewater glaciers of the Barents sea region. Full database is available on CD-ROM. Subsets of the database can be freely accessed at http://www.legos.obs-mip.fr/fr/equipes/glacio/integral.html (LEGOS contributions) and http://dib.joanneum.at/integral (JR_DIB contributions). New knowledge on changes of glacier frontal positions for Novaya Zemlya and Austfonna, presented as maps, are also available at http://www.legos.obsmip.fr/fr/equipes/glacio/integral.html. Correction of ionospheric effects A study has been completed of a method for correcting ionospheric effects in the form of azimuth streaks on the offset maps in SAR interferometry. The phase gradient approach allows measurement of the phase variations along the synthesised aperture. The phase variations may thus be used to make image focusing more precise and hence to delineate the ionospheric effects on SAR images.

A study has been completed of a method for correcting ionospheric effects in the form of azimuth streaks on the offset maps in SAR interferometry. The phase gradient approach allows measurement of the phase variations along the synthesised aperture. The phase variations may thus be used to make image focusing more precise and hence to delineate the ionespheric effects on SAR images.

Simulated Cryosat data for Austfonna, Kronebreen, Kongsvegen (all Svalbard) and Svartisen (northern Norway) data were created. This allows potential users of Cryosat 2 to examine in advance of whether this is a useful source of data for their work on these or similar glaciers. Several of the glaciers for which there are simulated data have significant topography and were not the prime focus of the mission requirements for Cryosat. One of the glaciers, Austfonna, is one of the largest ice masses in Europe (8000 square metres) and until recently, very little was known about it.

A robust and direct estimation technique of glacier motion based on satellite L-band SAR data has been developed. With this method the registration offsets of two SAR images are and used to estimate the displacement of glaciers. Offset-tracking is a welcome alternative to SAR interferometry when the latter is limited by rapid flow and large acquisition time intervals between the two SAR images. The innovative aspect is the use L-band SAR data, for which experience is limited. The results obtained so far for Arctic glaciers using SAR data acquired by a satellite operated until 1998 (the Japanese Earth Resources Satellite JERS-1) are significant in expectation of data from the PALSAR sensor onboard the Japanese Advanced Land Observing Satellite (ALOS) launched in early 2006. The estimated error of the JERS-1 offset tracking derived displacement is on the order of 20 m/year.

Retrieval of motion fields of glaciers and ice sheets using repeat pass imaging radar data. Optionally interferometric techniques or image correlation are applied. Application for studies of glacier dynamics and glacier climate interaction.

The system for modelling glacier mass balance and runoff uses satellite-derived information in synergy with meteorological observations. Multispectral optical and synthetic aperture radar (SAR) satellite data are used to map the extent of glaciers, retrieve surface albedo, and monitor the temporal evolution of snow and ice areas. Surface motion of glaciers is derived from repeat pass SAR images by means of interferometric analysis. A conceptual, semi-distributed model is applied for calculating daily changes of glacier mass and runoff. For model input temperature and precipitation data from meteorological stations are extrapolated to DEM grids and integrated with satellite-based time series of snow and ice extent. The model was successfully applied to glaciers in the Alps and Norway.

Glacier surface velocities from Svartisen, Unteraargletscher, Svalbard, Novaya Zemlya and Franz Josef Land were derived from satellite SAR data using interferometry and offset-tracking. Satellite SAR data were acquired between 1991 and 1998 from ERS-1, ERS-2 and JERS with acquisition time intervals between 1 and 44 days.

Basin-wide statistics of ice volume flux from margin change and ice velocity for the Austfonna ice sheet in Svalbard have been calculated. Velocity data from InSAR, and ice thickness data collected by SPRI in 1983 and 1986 were used. These values are a major contribution in estimating changes in sea level to due to glacier and ice sheet melting.

Simultaneous measurements were made over a period of several days of glacier surface velocity and basal sliding, as well as the subglacial pressure under Engabreen, Svartisen in Northern Norway. The measurements were made using the Svartisen Subglacial Laboratory in order to gain access to the ice-rock interface. Earth pressure cells installed at this interface measured the basal pressure, and three GPS stations on the glacier within 1 km distance, measured the surface velocity. Measurements were made over a period of several days in April 2006. This gave a unique dataset that shows how these important glacier parameters are related.

Three years (2004-2006) of mass balance, surface topography changes, ice surface velocities and meteorology data were obtained for Austfonna on Austlandet in Svalbard, the largest icecap in the European Arctic.

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