The GOCE User Toolbox – GUT

– An ESA effort to facilitate the use of GOCE Level-2 products.

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. 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.

 

 

Contact  

Per Knudsen

 


Background

The GOCE User Toolbox

Future Work

Project management



Background

 

The Gravity and Ocean Circulation Experiment - GOCE satellite mission is a new type of Earth observation satellite that will measure the Earth gravity and geoid with unprecedented accuracy. Combining GOCE geoid models with satellite altimetric observations of the sea surface height substantial improvements in the modelling of the ocean circulation and transport are foreseen. No ocean circulation products are planned to be delivered as level-2 products as part of the GOCE project so that a strong need exists, for oceanographers, to further process the GOCE level-2 geoid and merge it with Radar Altimetry. The primary requirement of oceanographers is to have access to a geoid and its error covariance at the highest spatial resolution and accuracy possible, although required resolution depends on application. For effective use of the geoid data, knowledge of the error covariance is mandatory.

 

Within the ESA supported GUT Specifications project, the user requirements for GUT associated with geodetic, oceanographic and solid earth applications were consolidated. For all applications the absolute minimal requirement of the toolbox includes the computation of geoid heights from the set of spherical harmonic coefficients at a given user-specified harmonic degree and order. For oceanographic applications the key quantity to be computed is the mean dynamic topography which basically is the height of the mean sea surface relative to the geoid. For this application GUT provide the tools for converting the mean sea surface and the geoid into the same geodetic system and for carrying out the needed filtering to compensate for the different resolution capabilities of the two surfaces. Furthermore, a-priori mean dynamic topography models derived from e.g. ocean circulation models, may be used.

 

 

The GOCE User Toolbox

 

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. 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.

Hence, the GUT package includes:

  • The source package for building on UNIX/Linux/Mac Binary packages for Linux and Windows that include BratDisplay (v2.0.0b)
  • The GUT Algorithm Description and User Guide (v1.2)
  • The GUT Tutorial (Beta version)
  • The GUT Install Guide (applicable to ALL packages).

The a-priori data package gut-apriori.zip is available as well.

GUT use GOCE data associated with the following GOCE-L2 products:

  • EGM_GCF_2: Spherical harmonic series in ICGEM format EGM_GEO_2: Grid with geoid heights in Grid format
  • EGM_GAN_2: Grid with gravity anomalies in Grid format
  • EGM_GVE_2: Grid with east-west vertical deflections in Grid format
  • EGM_GVN_2: Grid with north-south vertical deflections in Grid format
  • EGM_GVC_2: Variance-covariance matrix file of the spherical harmonics coefficients

These products will be stored in XML format, except for the Variance-Covariance Matrix (Internal HPF VCM format)

In addition GUT uses auxiliary data such as MSS and errors, MDT, DEM in NetCDF format (COARDS/CF standard).

 

/english/-/media/Institutter/Space/English/research/projects/gut/gut_01_384.ashx 

 

GUT is a command line processor. Its output may be exported and visualised using the ESA Basic Radar Altimetry Toolbox BRAT.

 

Applications of the Variance-covariance Matrix require additional software not included in GUT. The software has been developed by Georges Balmino and made available to the community. Those applications require heavy computational resources. In the current version of GUT documentation and tutorial they are not supported.

 

 

Future Work

 

The GUT will be further developed through a collaborative effort where the scientific communities participate. Originally, the idea about the scope of a GOCE toolbox exists came from the scientific users, especially from experience gained through GRACE data processing. Any new effort should build directly on this insight and should expand on user needs in a flexible way. The EU supported GOCINA and GOCINO projects are another source of valuable information about needs and solutions that will be consulted while developing GOCE user needs and toolbox functionalities.

 

 

Project Management

 

The GUT has been developed in a European coordinated effort supported by ESA. The objective of the GOCE User Toolbox Specifications study (GUTS) was to develop – in close collaboration with ESA's HPF effort – algorithms and input and output specification for the subsequent generation of a user toolbox that is required by the general science community for the exploitation of GOCE level 2 and ERS-ENVISAT altimetry.

 

The GUT project dealt with the actual creation of the GOCE User Toolbox. The objective of this activity was to develop the first generation of a user toolbox that is required by the general science community for the exploitation of GOCE level 2 data. The purpose of this study is accordingly to:

  • Review toolbox specification and define technical requirements, Develop the first generation toolbox based on existing software,
  • Introduce visualisation functions via GUI based on BRAT,
  • Develop toolbox tutorial,
  • Evaluate and test the toolbox.

Furthermore, two supporting scientific studies are carried out; one on a new Mean Sea Surface and one on error covariance matrix handling.

Contact

Per Knudsen
Professor
DTU Space
+45 45 25 97 18