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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #204721

Title: Comparison of turbulent statistics and spectra at two heights over a semi-arid grassland surface

item Prueger, John
item HIPPS, L
item Scott, Russell - Russ
item Kustas, William - Bill
item Hatfield, Jerry

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/25/2006
Publication Date: 5/25/2006
Citation: Prueger, J.H., Hipps, L.E., Eichinger, W.E., Scott, R.L., Kustas, W.P., Hatfield, J.L. 2006. Comparison of turbulent statistics and spectra at two heights over a semi-arid grassland surface. In: Proceedings of the 27th Conference on Agricultural and Forest Meteorology, May 22-25, 2006, San Diego, CA. 2006 CDROM.

Interpretive Summary:

Technical Abstract: Understanding the turbulent exchange of mass and energy from a surface remains essential to appropriate characterization and quantification of the components of surface energy balance. This is particularly true for arid and semi-arid regions that often contain surfaces that are highly heterogeneous, exhibit significant topographical features, abrupt changes in vegetation cover and contain large spatial and temporal gradients in the water and energy balance components. Collectively all of the above can cause the physical turbulent exchange processes at a surface to often significantly deviate from fundamental assumptions associated with eddy covariance measurements of energy and mass. As part of the Soil Moisture Experiment 2004 (SMEX04) eddy covariance measurements (10 Hz) at two heights (2 & 10 m AGL) in a sub-watershed basin in Walnut Gulch, AZ were conducted during the monsoon season over a heterogeneous grassland surface. Turbulence statistics, spectra, cospectra and fluxes of heat and water vapor were computed, evaluated and compared for the two heights. Unique spectral features related to near free convective conditions at the surface were observed and will be presented. The effects of surface heterogeneity in terms of source strength turbulent contributions to the measurements at two heights will also be discussed.