1. 1 Basic Radar Altimetry Toolbox & Radar Altimetry Tutorial

2. 2 Basic Radar Altimetry Toolbox & Tutorial A new set of tools for all altimetry users A Joint project between ESA and CNES, benefiting from 14 years of Aviso’s experience Statements: –15 years of altimetry and at least as many data formats as satellites, –A growing number of non-expert users of the data, –Scientists also need easy-to-use data products and tools!s Basic Radar Altimetry Toolbox (BRAT) –Data reading, processing and visualisation –All altimetry data from official data centres since ERS-1 (1991) Radar Altimetry Tutorial (RAT) ( http://www.altimetry.info )http://www.altimetry.info –A tutorial describing altimetry, for the users –technique, applications and missions –Products fact sheets and data use cases

3. 3 Radar Altimetry Tutorial Applications –Geodesy & solid Earth –Ocean –Ice –Climate –Weather –Hydrology & land –Coastal Data use cases Altimetry –How it works –Data flow –Future improvements Altimetry missions –Past missions –Current missions –Future missions Products –Data –Software –Documentation –Toolbox http://www.altimetry.info

4. 4 Basic Radar Altimetry Toolbox (BRAT) Windows & Linux ERS-1 and 2, Topex/Poseidon, Geosat Follow-on, Jason-1, Envisat, and the future Cryosat missions. From Aviso, ESA, PoDaac, Noaa From Sensor Geophysical Data Record to gridded merged data Four main components: 1.Data reading 2.Processing routine functions 3.Visualisation functions 4.Graphic User Interface (GUI) 5.Save/restore capabilities for workspaces, operations, parameterisation, etc (data and methods re-use or exchange between users). Present version: v1.0.2

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6. 6 Maps (different projections) Data visualisation Curves

7. 7 Formulas: editing and computing data Formulas are combinations of data fields and functions (including arithmetic operators, + - / *) Use: –as a ‘data expression’: to compute a combination of data fields (e.g. SSH) –or as a data selection: to do a complex selection on the data fields Pre-defined formulas can be used User-made formulas can be saved And re-used in either the same workspace, or imported in another one

8. 8 Editing data Data editing is necessary to remove altimeter measurements having lower accuracy  editing using flags e.g. altim_landocean_flag = 0 (to check for values over ocean only in Envisat GDRs)  editing using thresholds E.g.-130 m < altitude –range < 100 m 0 m < SWH < 11 m -0.5 m < wet tropo corr < -0.001 m -0.2 deg² < antenna mispointing < 0.11 deg² …

9. 9 Data editing

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11. 11 Mean Sea Level Anomalies for November 1997

12. 12 Eddy Kinetic Energy on 17 August 2005

13. 13 © Noaa/AOML Note:11 days later… Hurricane Katrina

14. 14 Sea Level Anomalies Standard deviation over November 1997

15. 15 Hydrology : Aral Sea

16. 16 1993 2002 Aral Sea level height from T/P GDR data nearly ten years apart

17. 17 For comparison:

18. 18 For more information http://www.altimetry.info (mirror on http://earth.esa.int/brat/ )http://www.altimetry.infohttp://earth.esa.int/brat/ Or Ask me for a demonstration this week (also at Envisat Symposium late April in Montreux)