Tuesday, 14 May 2002: 2:45 PM
Mapping the thermal climate of the HJ Andrews Experimental Forest, Oregon
The HJ Andrews Experimental Forest in the central Oregon Cascades provides a unique opportunity to study spatial climate patterns on a relatively small scale. Historical records at the 116 square km site provide a solid 30-year dataset from over 35 climate stations. Thermal regimes at the HJ Andrews are generally known but the effects of its complex topography and canopy cover on temperature have been poorly understood. In this study, spatial variations in mean monthly maximum and minimum temperatures were estimated on a 50-meter grid. Terrain and canopy were determined to be the primary influences on temperature and the 30-year dataset was corrected to account for these factors. The Image-Processing Workbench (IPW) was used to estimate incoming solar radiation at all sites taking into account seasonal cloudiness and topographic attenuation. Together with fisheye photographs, the amount of insolation blocked by only forest canopy was determined, and specific site pairs analyzed to calculate functions for correcting temperatures ‘out of the canopy’. PRISM was used to generate high-resolution temperature maps in the absence of vegetation based on these corrected datasets and the IPW monthly radiation coverages. Methods, results, and applicability of results to current and future HJ Andrews research will be discussed.