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The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. The entire network is uplifting in response to past and present-day changes in ice mass. Crustal displacement is largely accounted for by an annual oscillation superimposed on a sustained trend. The oscillation is driven by earth's elastic response to seasonal variations in ice mass and air mass (i.e., atmospheric pressure). Observed vertical velocities are higher and often much higher than predicted rates of postglacial rebound (PGR), implying that uplift is usually dominated by the solid earth's instantaneous elastic response to contemporary losses in ice mass rather than PGR. Superimposed on longer-term trends, an anomalous 'pulse' of uplift accumulated at many GNETstations during an approximate six-month period in 2010. This anomalous uplift is spatially correlated with the 2010 melting day anomaly. [ABSTRACT FROM AUTHOR]

Satellite radar altimetry has been monitoring the earth's oceans from space for several decades.However, only the GEOSAT and ERS-1 geodetic mission data recorded more than a decade ago provide altimetry with adequate spatial coverage to derive a high-resolution marine gravity field. The original geodetic mission data suffer from degradation in quality and coverage close to the coast and in Polar Regions as well as the occasionally wrongly retracking of these, even in the open ocean. In order to improve the quality of these geodetic mission data and to derive a new improved global marine gravity field called DNSC08GRA, a new double retracking technique for analyzing the waveform data has been developed. Multiple retracking allows the system to retrack more data to increase the spatial coverage of the data. Subsequently, a second retracking run is used to enhance the SSH determination by using information from the first fitting to inform the second set of retrackers about smoothly varying sea state parameters. The development of the new global marine gravity field DNSC08GRA is described in this paper. Besides application of new retracking techniques the radar altimetry has been processed using EGM2008 as reference and augmented with ArcGP gravity data and laser altimetry from ICESat to close the Polar gap. DNSC08GRA is seen to perform significantly better than previous global marine gravity field like KMS02. The improvement in accuracy is better than 20% in general, but in coastal regions, the improvement is in many places of the order of 40-50% compared to older global marine gravity field KMS02. [ABSTRACT FROM AUTHOR]

The GRACE mission will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more subtle climate signals which GRACE aims at. In this analysis the results of Knudsen and Andersen (2002) have been verified using actual post-launch orbit parameter of the GRACE mission. The current ocean tide models are not accurate enough to correct GRACE data at harmonic degrees lower than 47. The accumulated tidal errors may affect the GRACE data up to harmonic degree 60. A study of the revised alias frequencies confirm that the ocean tide errors will not cancel in the GRACE monthly avenged temporal gravity fields. The S2 and the K2 terms have alias frequencies much longer than 30 days, so they remain almost unreduced in the monthly averages. Those results have been verified using a simulated 30 days GRACE orbit. The results show that the magnitudes of the monthly averaged values are slightly higher than the previous values. This may be caused by insufficient sampling to hilly resolve and reduce the tidal signals at short wavelengths and close to the poles. [ABSTRACT FROM AUTHOR]

Focuses on fraud and irregularities affecting the European Union's budget. Action to combat fraud; Examples of anti-fraud cases; Role of UCLAF, French acronym for the unit for the coordination of fraud prevention; Introduction of an early warning system.

The effects of residual ocean tide signals on altimetric mesoscale variability estimates are analyzed in the north east Atlantic region using one year of Geosat Exact Repeat Mission data. The variability is evaluated along collinear tracks and covariance functions are determined. Initial results show that the average variability is about 10 cm. Variability values of 15-20 cm are found between Iceland and the Faeroe Islands and values up to 1/2 m are found near the coast of the UK. Then a procedure for estimation of ocean tide signals combined with the collinear analyses was tested. A separation of the estimated tide residuals associated with M, S, and N resulted in a significant reduction of the variability. The average variability decreased to 5 cm and the temporal correlations vanished. A reduction of the large variability values from 15-50 cm to 5-10 cm demonstrates that significant residual ocean tide signals can be estimated and removed efficiently in a collinear analysis of the mesoscale ocean variability. [ABSTRACT FROM AUTHOR]

Sea level change is an important indicator of climate change. Our study focuses on the sea level budget assessment of the Arctic Ocean using: (1) the newly reprocessed satellite altimeter data with major changes in the processing techniques; (2) ocean mass change data derived from GRACE satellite gravimetry; (3) and steric height estimated from gridded hydrographic data for the GRACE/Argo time period (2003–2016). The Beaufort Gyre (BG) and the Nordic Seas (NS) regions exhibit the largest positive trend in sea level during the study period. Halosteric sea level change is found to dominate the area averaged sea level trend of BG, while the trend in NS is found to be influenced by halosteric and ocean mass change effects. Temporal variability of sea level in these two regions reveals a significant shift in the trend pattern centered around 2009–2011. Analysis suggests that this shift can be explained by a change in large-scale atmospheric circulation patterns over the Arctic. The sea level budget assessment of the Arctic found a residual trend of more than 1.0 mm/yr. This nonclosure of the sea level budget is further attributed to the limitations of the three above mentioned datasets in the Arctic region. [ABSTRACT FROM AUTHOR]

The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. We provide 3D displacement time series from GPS available at (https://catalog-intaros.nersc.no/dataset/ice-mass-change-of-the-greenland-ice-sheet) to study uplift in response to present-day changes in ice mass. We compare present-day 3D deformations with modeled results. To retrieve 3D elastic displacements from GPS time series, we correct our observations for glacial-isostatic adjustment and tectonic plate motion. To model 3D elastic displacements, we first estimate mass loss using 1995–2014 NASA's Airborne Topographic Mapper (ATM) flights derived altimetry, supplemented with laser altimetry observations from the Ice, Cloud, and Land Elevation Satellite (ICESat) during 2003–2009; the airborne Land, Vegetation, and Ice Sensor (LVIS) instrument during 2007–2013; radar altimetry from the CryoSat-2 satellite during 2010–2018; and European Remote-Sensing Satellite–1 (ERS-1) and ERS-2 data during 1995–2003. We convert the volume loss rate into a mass loss rate accounting for firncompaction. We predict the elastic displacements by convolving mass loss estimates with Green's functions for vertical and horizontal displacements. [ABSTRACT FROM AUTHOR]

The universal altimetry toolbox BRAT (Broadview Radar Altimetry Toolbox) is a collection of open source tools and tutorial documents designed to facilitate the processing of radar altimetry data. It can read all previous and current altimetry missions' data. It now incorporates the capability to read the upcoming Sentinel-3 L1 and L2 products. ESA endeavoured to develop and supply this new capability to support the users of the Sentinel-3 mission.The BRAT suite is mostly made of command line tools, of which the BratGUI is the front-end. BRAT can be used in conjunction with MATLAB/IDL (via reading routines) or C/C++/Python/Fortran via a programming API, allowing users to obtain the desired data, bypassing the data-formatting hassle. BRAT can also be used to simply visualise data quickly, or to translate the data into other formats such as NetCDF, ASCII text files, KML and raster images from the data (JPEG,...).Several kinds of computations can be done within BRAT, involving both user-defined combinations of data fields that can be saved for posterior use and the BRAT's predefined formulas from oceanographic altimetry. BRAT also includes the Radar Altimeter Tutorial, which contains an extensive introduction to altimetry, showing its applications in different fields. Use cases are also available, with step-by-step examples, covering the toolbox usage in different thematic contexts.Both the toolbox and the tutorial can be accessed through http://earth.esa.int/brat or http://www.altimetry.info/. The GOCE User Toolbox GUT is a compilation of tools for the utilisation and analysis of GOCE Level 2 products. GUT support applications in Geodesy, Oceanography and Solid Earth Physics. It can compute and process a range of higher level products relevant to the fields of oceanography, solid earth physics and geodesy at global and regional scales. GUT can also process any global gravity model in the ICGEM format. GUT may be used on Windows PCs, UNIX/Linux workstations and Mac and comes as fully open source software under GNU GPL licence. GUT generates all output files in netCDF format in compliance with the CF Conventions, and gridded results may be visualised using the Brat Display tool from ESA's Broadview Radar Altimetry Toolbox (BRAT). Advanced users can easily extend the toolbox in accordance with the workflow based processing design principles, and contribute these enhancements to the GUT user community. Originally only a command line tool, the current version of GUT is 3.0. This version has been enhanced with a newly developed graphical user interface. This interface is built on top of the command-line interface, providing a more user friendly alternative to it.The GUT Tutorial provides information and guidance in how to use the toolbox for a variety of applications. GUT consists of a series of advanced computer routines that carry out the required computations. It may be used on Windows PCs, UNIX/Linux Workstations, and Mac. The toolbox is supported by The GUT Algorithm Description and User Guide and The GUT Install Guide. A set of a-priori data and models are made available as well. The toolbox and the tutorial can be accessed through: http://earth.esa.int/gut [ABSTRACT FROM AUTHOR]