Hurricane Ike tracked by ESA's Envisat( Residents along the Gulf Coast are b...)

Residents along the Gulf Coast are bracing for Hurricane Ike as it travels over the Gulf of Mexico after ripping through Cuba and Haiti. ESA's Envisat satellite is tracking the storm, which is forecast to make landfall on the Texas coast by 13 September.

Knowing the strength and path of hurricanes is critical for issuing timely warnings. Earth observation (EO) satellites are key means of providing synoptic data on the forces that power the storm, such as cloud structure, wind and wave fields, sea surface temperature and sea surface height.

Thanks to Envisat's unique capability to acquire optical and radar imagery over the same area of the Earth simultaneously, the top and bottom of a hurricane can be viewed at the same time. The unique view of Hurricane Ike on the left is an example of combined optical and radar images, showing the swirling cloud-tops and the shape of the wind-driven sea surface.

Moreover, satellite-based radar instruments have the capability of penetrating heavy clouds and precipitations and can provide day and night high-resolution observations of critical ocean parameters, such as local wind, waves and currents over a 400-km-wide region.

Using these capabilities specific to radar satellites, Dr Bertrand Chapron of IFREMER, the French Research Institute for Exploitation of the Sea, and Dr Fabrice Collard of France's CLS radar application division in Brest, have developed sets of algorithms that allow data from the Advanced Synthetic Aperture Radar (ASAR) instrument aboard Envisat to be processed in Near-Real Time (NRT) and to produce state-of-the-art ocean parameters.

Taking advantage of the broad availability of Envisat ASAR wide swath acquisitions taken over the hurricane region, the corresponding sea surface roughness map, wind speed map and surface current are made widely available on the SOPRANO ocean products demonstration website developed with ESA.

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