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United States Department of Agriculture

Agricultural Research Service

Title: Comparision of estimation methods to determine turbulent fluxes over snow in a mountainous forested environment

Authors
item Reba, Michele - UNIV OF IDAHO
item Marks, Daniel
item Link, Timothy - UNIV OF IDAHO
item Winstral, Adam

Submitted to: Trans American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: November 7, 2005
Publication Date: December 15, 2005
Citation: Reba, Michele L., Marks, D., Link, Timothy, and Winstral, A. 2005. Comparison of estimation methods to determine turbulent fluxes over snow in a mountainous forested environment. abstract C21A-1068, Eos, Transactions of the American Geophysical Union, 86(52):F431

Technical Abstract: The turbulent exchange of sensible and latent heat and mass between the snowcover and the atmosphere can represent a significant component of the snowcover energy and mass balance in mountainous environments. These fluxes are computed in land surface and energy balance snowmelt models, though few measurements exist for comparison or validation. Where measurements do exist, they employ eddy covariance (EC) instrumentation. Two outputs are generated with typical eddy covariance instrumentation: time series data, which is later corrected and fluxes calculated, and 30-minute flux summaries, which are calculated directly without correction. Due to data storage limitations, the flux summaries are often stored instead of raw time series data. More commonly, turbulent fluxes are modeled from slow response meteorologic data. This research considers data taken from within a forested site over snow in order to compare turbulent fluxes estimated from the two eddy covariance output types and modeled turbulent fluxes. Preliminary results indicate corrected time series fluxes are approximately 15%-20% smaller than 30-minute flux summaries, and approximately equivalent to the modeled fluxes at this site. The conditions under which the labor-intensive time series corrections are mandatory are described. Also, the conditions under which the 30-minute flux summaries and modeled fluxes are similar to time series estimated turbulent fluxes are described. The steps used to process, correct, and analyze (including co-spectra) the time series eddy covariance data are presented. The data used in this analysis are from a uniform conifer stand during the winter of 2003 as part of the Cold Lands Processes Field Experiment (CLPX). This research improves our understanding of how measurements of turbulent fluxes vary by estimation method and sets the stage for improved modeling of turbulent fluxes.

Last Modified: 12/21/2014
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