Slope vectorn. The magnitude and direction of the slope factor.
Slope factor represents the effect of slope steepness on propagating flux in the Rothermel (1972) surface fire spread model. Slope vector is the combined magnitude and direction of the slope factor. Direction of the slope factor is directly opposite the aspect. For example, on a southwest facing slope (aspect = 225 degrees), the direction of the slope vector is northeasterly (45 degrees).
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The length of the slope vector is the slope factor. The wind and slope vectors are combined to produce the resulting effective spread vector.
