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Basic Radar Altimetry Toolbox: a new set of tools for all altimetry users

04 July 2007

ESA and CNES announce the release of the Basic Radar Altimetry Toolbox (BRAT), a set of software and information dedicated to radar altimetry satellites, developed by CLS (Collecte Localisation Satellites).

For more than 16 years, since the launches of the ERS-1 and Topex/Poseidon satellites, altimetry has revolutionized oceanography - among other fields - by providing information on the state of the ocean with measurements of the height of the ocean surface.

Radar altimeters are also fundamental instruments for globally monitoring continental ice-mass imbalance and continental surface water levels in rivers and lakes - all indicators of climate change. In particular, the future Cryosat's mission is dedicated to monitoring very precise changes in the elevation and thickness of polar ice sheets and floating sea ice. These observations will determine whether or not our ice masses are thinning due to global warming.

However, with such a wide, ever growing, community of users, altimetry had no multi-mission, dedicated, tool adapted to its users' specific needs.

The Basic Radar Altimetry Toolbox is a collection of tools and tutorial documents designed to facilitate the use of radar altimetry data. It is able to read most distributed radar altimetry data from all the satellites, to do some processing, data editing and statistic over them, and to visualise the results.

Tested at the 2006 ESA Advanced training course on ocean remote sensing in Hamburg (Germany), it will be the basis of the 2007 altimetry practical session in Hangzhou (China).

It has also met the interest of the altimetry users' community at the CNES/NASA Ocean Surface Topography Science Team meeting, and of the Envisat users' community at the ESA Envisat Symposium last March and April.

The BRAT package contains a set of software tools and interfaces - with a Graphical User Interface -, that allow users to easily specify the processing parameters.

The tools' functionalities include data import and export, visualisation and quick-look, data editing and resampling, computation of statistical parameters and combinations of data fields. The ability of saving the context and formulas, and to exchange them between users, is also built-in.

BRAT is provided as open source software, enabling user community participation in further development and quality improvement. The tools are available for Windows 2000/ XP, GNU/Linux RedHat EL 4 (or any distribution of Linux with Xfree 4.4.0 libraries).

BRAT is able to read ERS-1 and 2, Topex/Poseidon, Geosat Follow-on, Jason-1, Envisat, and the future Cryosat missions altimetry data from official data centres (ESA, NASA/JPL, CNES/Aviso, NOAA), and this for different processing levels, from level 1B (Sensor Geophysical Data Record) to level 3/4 (gridded merged data).

The Radar Altimetry Tutorial, within the BRAT package, gives general information about altimetry, technique and applications, as well as an overview of the missions, access to data, software and documentation. It also presents a series of data use cases, showing the basic methods for some of the most frequent ways of using altimetry data.

For software downloads and upgrades, documentation updates and the on line tutorial (including data use cases) go to http://earth.esa.int/brat/.

The BRAT Toolbox and its Tutorial will be presented at IUGG next week. DVDs will be available at the ESA exhibition booth.

"J. Benveniste (ESA) & N. Picot (CNES)"

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