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The Influence of Ground-Relative Flow and Friction on Near-Surface Storm-Relative Helicity
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2021
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Source: Journal of the Atmospheric Sciences, 78(7), 2135-2142
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Journal Title:Journal of the Atmospheric Sciences
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Description:Recent studies have highlighted the importance of near-ground storm-relative helicity (SRH) in supercell and tornado processes and how surface friction can play a role. In this study, we use an analytical approach to examine how uniform changes to the ground-relative wind profile above the near-ground layer influence SRH within the near-ground layer. We show how the ground-relative influence of surface friction alters the near-ground shear profile. For idealized semicircular and straight shear profiles, increasing preexisting ground-relative flow above the near-ground layer yields increasing SRH. The magnitude of the SRH increase is sensitive to storm motion, with more deviant motion yielding greater SRH increases given the same increase in ground-relative flow. Supercells may be more susceptible to storm-induced SRH enhancements given their deviant motion and ability to increase ground-relative flow in the background environment.
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Source:Journal of the Atmospheric Sciences, 78(7), 2135-2142
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