Modeling The Surface Energy Balance On Montane Hill Slopes
Rush, Michael 1 ; Rajaram, Harihar 2 ; Anderson , Robert 3
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The Intergovernmental Panel on Climate Change (2013) warns that alpine ecosystems are extremely vulnerable to climate change due to short growing seasons, thin soils, sparse vegetation, melting glaciers, and thawing permafrost. Projecting hydrologic responses to warming presents a need for highly-robust, spatially-distributed, coupled thermal-hydrologic models that characterize the heterogeneity of solar insolation, vegetation, and snowpack dynamics. A solar radiation model incorporating cloud cover, canopy interception, and hill slope, aspect, and shading (Dingman, 2015) is coupled to a snow accumulation and ablation model (Tarboton and Luce, 1996). Model results are validated at Gordon Gulch (Figure 1), a seasonally snow-covered montane catchment in the Colorado Rockies managed by the Boulder Creek Critical Zone Observatory. The field site features two instrumented hillslopes with generally opposing aspects: the north-facing slope is forested with lodgepole pine, while the south-facing slope is populated with sparse ponderosa pine, low-lying grasses, shrubs such as juniper and kinnikinnick, and patches of bare soil. The snowpack on the north-facing slope persists throughout much of the winter season, while the snowpack on the south-facing slope is highly ephemeral. Preliminary model results demonstrate that surface energy balance methods are capable of representing the full range of physical processes that drive hydrologic processes on hill slopes.
Dingman, S.L. 2015. Physical Hydrology. 3rd Edition, Waveland Press, Inc., Long Grove.
Tarboton DG, Luce CH. 1996. Utah Energy Balance Snow Accumulation and Melt Model (UEB), Computer model technical description and users guide: Utah Water Research Laboratory and USDA Forest Service Intermountain Research Station.