Use of Topographic Elevation Models to Identify Thermal Hotspots in Alpine Areas

Abstract

Thermals are part of the atmospheric energy flow caused by solar irradiation.  The question behind this project, called TherMap, has been whether variations of the solar irradiance, caused by the local topography, could be a valid predictor of thermals under ideal meteorological conditions.  Using digital elevation data the local irradiance, therefore, was computed for each cell, date and time, and the results displayed on maps, leading to first plausible results for the morning hours of mountain areas.  In a second step these models were refined to consider the thermal inertia of the soil and the air, the different vegetation factors, as well as the reflection of snow surfaces.  For Alpine areas the resulting maps turned out to show a high level of agreement with superimposed flight tracks.  For topographically less differentiated regions, like the Jura, the results were mixed.  No conclusive results could be obtained for topographically still smoother landscapes, where factors other than topographical ones are likely to be predominant.