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Fundamental causes of model inaccuracies in predicting wind-blown sand fluxes
  • Marcelo Chamecki,
  • Jasper F. Kok
Marcelo Chamecki
University of California, Los Angeles

Corresponding Author:chamecki@ucla.edu

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Jasper F. Kok
Department of Atmospheric and Oceanic Sciences University of California, Los Angeles
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The wind-blown flux of sand generates dunes, wind erosion, and mineral dust aerosols. Existing models predict the sand flux using the wind friction velocity that characterizes near-surface turbulent momentum fluxes. However, these models struggle to accurately predict sand fluxes. Here we analyze root causes of these model discrepancies using high-frequency field measurements of winds and sand fluxes. We find that friction velocity is only predictive of sand fluxes on long timescales, when it correlates with horizontal wind speed. On shorter timescales, and for non-ideal surface conditions, friction velocity is much less predictive, likely because the near-surface wind momentum budget is dominated by other, less predictable terms. We furthermore find that variability in 30-min averaged sand fluxes at a given friction velocity is not driven by changes in turbulence but by changes in surface conditions, raising a challenge for models. These findings can improve sand flux models and clarify their limitations.
06 Mar 2023Submitted to ESS Open Archive
09 Mar 2023Published in ESS Open Archive