Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Software and methods for snow covered area (SCA) and snow wetness (SW) mapping from SAR imagery

Norut IT has developed a set of tools and methods that together are the basis for generating snow covered area maps and snow wetness maps from synthetic aperture radar imagery. The tools are mainly implemented in the programming languages Envi/IDL under a common framework. Parts of the system have been separated as pre-compiled c-routines.

The system is based on using synthetic aperture radar data as input. In addition the system requires input from a digital elevation model and a basic land cover mask (glacier, lakes and forest themes). The system also requires a reference SAR input file for each SAR geometry to be processed.

The core classification of snow is done by applying the Nagler-approach (Nagler and Rott, 2001) where wet snow is classified by using its low radar backscattering as opposed to the higher backscatter by dry snow or bare soil. The current SAR image is thresholded against a reference SAR scene with the same satellite geometry that is known to contain dry snow or bare ground. In addition dry snow is inferred from this by using DEM information (see Malnes et al., 2002). Image pixels above the mean altitude of wet snow that are not classified as wet snow are assumed to be dry snow.

These methods are in them selves generic, and adaptable for several existing and future sensors, as well as for different geographical regions. Today, the system has been limited to certain geographical regions (mountainous parts of Southern Norway), and to certain sensors, and sensor modes (ERS, Envisat and Radarsat). It is, however, relatively easy to extend the system to other regions and other sensors.

NORUT IT intends to exploit its parts of the Envisnow snow parameter retrieval system in future applications and for commercial applications.

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Norut IT
P.O. 6434 Forskningsparken
9294 Tromsø
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