Quantification of surface layer turbulence using sensible heat values from energy balance versus aerodynamic methods

Steven Fiorino; Yogendra Raut; Jack McCrae; Santasri Bose-Pillai; Ben Wilson; Blaine Fourman

doi:10.1117/12.2677352

3 October 2023 Quantification of surface layer turbulence using sensible heat values from energy balance versus aerodynamic methods

Steven Fiorino, Yogendra Raut, Jack McCrae, Santasri Bose-Pillai, Ben Wilson, Blaine Fourman

Author Affiliations +

Proceedings Volume 12693, Unconventional Imaging, Sensing, and Adaptive Optics 2023; 126930N (2023) https://doi.org/10.1117/12.2677352
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

Surface layer optical turbulence values in the form of C_T² or C_n² are often calculated from surface layer temperature, moisture, and wind characteristics and compared to measurements from sonic anemometers, differential temperature sensors, and imaging systems. A key derived component needed in the surface layer turbulence calculations is the “Sensible Heat” value. Typically, the sensible heat is calculated using the “Bulk Aerodynamic Method” that assumes a certain surface roughness and a “friction velocity” that approximates the turbulence drag on temperature and moisture mixing from the change in the average surface layer vertical wind velocity. These assumptions/approximations generally only apply in free convection conditions. A more robust method, that applies when free convection conditions are not occurring, to obtain the sensible heat is via the Energy Balance or Bowen Ratio method. The use of the Bowen ratio – the ratio of sensible heat flux to latent heat flux – allows a more direct assessment of the optical turbulence-driving surface layer sensible heat flux than do more traditional assessments of surface layer sensible heat flux. This study compares surface layer C_T² and C_n² values using sensible heat values from the bulk aerodynamic and energy balance methods to measurements from instruments such as sonic anemometers, differential temperature sensors, and time-lapse imagery. This research further compares improvements to the calculations gained by using sonic anemometer eddy covariance values to obtain the friction velocity, and including humidity effects via covariance methods or simply using virtual temperature from the sonic anemometers.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Steven Fiorino, Yogendra Raut, Jack McCrae, Santasri Bose-Pillai, Ben Wilson, and Blaine Fourman "Quantification of surface layer turbulence using sensible heat values from energy balance versus aerodynamic methods", Proc. SPIE 12693, Unconventional Imaging, Sensing, and Adaptive Optics 2023, 126930N (3 October 2023); https://doi.org/10.1117/12.2677352

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