SNOW AND HYDROLOGIC PROCESSES IN THE INTERMOUNTAIN WEST
Location: Watershed Management Research
Title: Evaluation of measured and simulated turbulent components of a snow cover energy balance model in order to refine the turbulent transfer algorithm
Submitted to: Geoscience and Remote Sensing Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 27, 2007
Publication Date: December 8, 2007
Citation: Reba, M., Marks, D.G., Link, T., Pomeroy, J., Winstral, A.H. 2007. Evaluation of measured and simulated turbulent componets of a snow cover energy balance model in order to refine the turbulent transfer algorithm. EOS Transactions of the American Geophysical Union, 88(52) Fall Meeting Supplement, Abstract C34A-07.
Energy balance models use physically based principles to simulate snow cover accumulation and melt. Snobal, a snow cover energy balance model, uses a flux-profile approach to calculating the turbulent flux (sensible and latent heat flux) components of the energy balance. Historically, validation data for turbulent flux simulations have been difficult to obtain at snow dominated sites characterized by complex terrain and heterogeneous vegetation. Currently, eddy covariance (EC) is the most defensible method available to measure turbulent flux and hence to validate this component of an energy balance model. EC was used to measure sensible and latent heat flux at two sites over three winter seasons (2004, 2005, and 2006). Both sites are located in Reynolds Creek Experimental Watershed in southwestern Idaho, USA and are characterized as semi-arid rangeland. One site is on a wind-exposed ridge with small shrubs and the other is in a wind-protected area in a small aspen stand. EC data were post processed from 10 Hz measurements. The first objective of this work was to compare EC- measured sensible and latent heat flux and sublimation/condensation to Snobal-simulated values. Comparisons were made on several temporal scales, including inter-annual, seasonal and diurnal. The flux- profile method used in Snobal assumes equal roughness lengths for moisture and temperature, and roughness lengths are constant and not a function of stability. Furthermore, there has been extensive work on improving profile function constants that is not considered in the current version of Snobal. Therefore, the second objective of this work was to modify the turbulent flux algorithm in Snobal. Modifications were made to calculate roughness lengths as a function of stability and separately for moisture and temperature. Also, more recent formulations of the profile function constants were incorporated. The third objective was to compare EC-measured sensible and latent heat flux and sublimation/condensation to the modified Snobal simulated values. The final objective was to determine if the modified turbulent flux algorithm in Snobal results in hydrologically significant improvements to simulations.