Topographic Shielding
In ACE a mandatory sample attribute is the shielding factor, which is the product of the snow shielding and topographic shielding factors. ACE contains the standard calculation of topographic shielding from Gosse and Phillips, 2001 to determine the amount of shielding at a sample site resulting from local topography. Two versions are supplied, one with a resolution of 30 degrees and another with 45 degrees. The 30 degree topographic shielding is shown below:
Each mountain observation is represented as a compass point (North, NNE, etc), and the units for mountain height are degrees from horizontal. Similarly sample dip and strike are included below the compass. Variations with surface dip and topographic shielding from Gosse and Phillips, 2001 (Figure 15) are shown below:
A value of the shielding exponent m, is assumed as 2.3 but is allowed to vary as some sensitivity to atmospheric depth has been determined (Desilets pers comm):
To see a demonstration of this utility click here (requires Quicktime)