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ARS Home » Plains Area » Las Cruces, New Mexico » Range Management Research » Research » Publications at this Location » Publication #415501
Research Project: Knowledge Systems and Tools to Increase the Resilience and Sustainablity of Western Rangeland Agriculture

Location: Range Management Research

Title: An evaluation of different approaches for estimating shear velocity in aeolian research studies

Author
item ZHANG, PEI - New Mexico State University
item EDWARDS, BRANDON - New Mexico State University
item Webb, Nicholas - Nick
item TRAUTZ, ANDREW - Us Army Corp Of Engineers (USACE)
item GILLIES, JACK - Desert Research Institute
item ZIEGLER, NANCY - Us Army Corp Of Engineers (USACE)
item Van Zee, Justin

Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2024
Publication Date: 11/12/2024
Citation: Zhang, P., Edwards, B., Webb, N.P., Trautz, A., Gillies, J., Ziegler, N., Van Zee, J.W. 2024. An evaluation of different approaches for estimating shear velocity in aeolian research studies. Aeolian Research. 70-71:100945. https://doi.org/10.1016/j.aeolia.2024.100945.
DOI: https://doi.org/10.1016/j.aeolia.2024.100945

Interpretive Summary: This study evaluates different methods for estimating shear velocity in an open shrubland. We compared the differences in estimating shear velocity from different methods using the data collected over 7.5 months at the Jornada Experimental Range in the Chihuahuan Desert, southern New Mexico, USA. The differences in estimating shear velocity from different eddy covariance methods are within a reasonable range (±5%). We find the planar fit and invariants of the Reynolds stress tensor methods, which haven't been widely used, are viable options to estimate shear velocity in aeolian studies. Notably, differences in estimating shear velocity from the Law of the Wall and eddy covariance techniques can differ significantly over a range of wind speeds. These findings emphasize the importance of selecting methods carefully to accurately characterize boundary layer turbulence.

Technical Abstract: Sonic anemometry represents an important technological advance for aeolian studies, fostering better understanding of near-surface turbulence and improved methods for estimating shear velocity (u_*). Here, we compared u_* estimated from four methods for processing 3-D sonic data to calculate eddy covariance and from the Law of the Wall approach. Vector rotation is essential to the eddy covariance approach. Four rotation methods were compared: double rotation, triple rotation, planar fit, and an approach using invariants of the Reynolds stress tensor. Data were collected over 7.5 months at the Jornada Experimental Range in the Chihuahuan Desert, southern New Mexico, USA. u_* estimates from different data processing methods were compared to the double rotation method because of the wide application of double rotation method in aeolian geomorphology and other disciplines. On average, the differences in u_* estimates between the four rotation methods were within 5%. A range of -14.7~13.7% discrepancy for u_* estimates was found when comparing the Law of the Wall method to eddy covariance approach. We think that the differences in u_* estimates from different eddy covariance approaches fall within an acceptable range. The planar fit and the invariants of the Reynolds stress tensor methods, which haven't been widely used, are viable options to estimate u_* in aeolian studies. We find u_* estimates can differ significantly over a range of wind speeds when comparing estimates from the Law of the Wall with eddy covariance. This underscores the need for careful method selection to ensure accurate characterization of boundary layer turbulence.