Item: Slope scale modeling of snow surface temperature in topographically complex terrain
Title: Slope scale modeling of snow surface temperature in topographically complex terrain
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: J.M. Staples, E.E. Adams, A.E. Slaughter, and L.R. McKittrick, Department of Civil Engineering Montana State University, Bozeman, MT 59717
Abstract: In mountainous terrain, landscape strongly influences the thermal state of snow. An energy balance model, Radtherm/RT, can be used to account for topography in the calculation of snow temperature. For a specific location, a terrain model can be defined and using a connected ensemble of elements or facets. Each element has a specified terrain type with assigned thermal properties. Meteorological data are applied, and a one dimensional energy balance is calculated for each element. This energy balance includes conduction, convection, radiation, and latent heat; however, the calculation of radiation is unique. Taking into account topography, global position, and time, the model can be used to calculate incoming solar radiation for each facet as well as reflected short wave radiation and the exchange of long wave radiation between terrain surfaces. Light detection and ranging (LIDAR) topographic data with a one meter resolution were used to create two separate models (on the order of 104 m2) for two test areas at the Yellowstone Club in southwest Montana. Meteorological data were collected for these two slopes and used as input for Radtherm/RT to calculate surface temperature and mass flux for each facet in the model. The results for facets in different locations were compared to investigate the effects of local topography. These results were also compared with measured temperatures and observations of surface hoar growth. Readily available USGS topographic data with a 30 meter resolution were used to create a model (on the order of 106 m2) containing both slopes. For this larger scale model, surface temperatures and mass flux were again calculated and compared with results for the slope scale models. Because LIDAR data are costly to obtain and create very large files, the use of USGS data is preferred for the application of Radtherm/RT in other large areas. At this point, the significant result has been the ability of Radtherm/RT to model surface temperature that varies with local topography at the slope scale.
Keywords: snow surface, temperature, topography, energy balance, modeling, radiation
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