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arXiv · 1505.00448

Penetrative turbulence associated with mesoscale surface heat flux variations

Jahrul M. Alam·M. Alamgir Hossain
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Abstract

This article investigates penetrative turbulence in the atmospheric boundary layer. Using a large eddy simulation approach, we study characteristics of the mixed layer with respect to surface heat flux variations in the range from 231.48 W/m$^2$ to 925.92 W/m$^2$, and observe that the surface heterogeneity on a spatial scale of $20$ km leads to downscale turbulent kinetic energy cascade. Coherent fluctuations of mesoscale horizontal wind is observed at 100m above the ground. Such a surface induced temporal oscillations in the horizontal wind suggest a rapid jump in mesocale wind forecasts, which is difficult to parameterize using traditional one-dimensional ensemble-mean models. Although the present work is idealized at a typical scale (20km) of surface heterogeneity, the results help develop effective subgrid scale parameterization schemes for classical weather forecasting mesoscale models.

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Jahrul M. Alam, M. Alamgir Hossain. 2015-05-03. Penetrative turbulence associated with mesoscale surface heat flux variations. https://arxiv.org/abs/1505.00448

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