The influence of ground-relative flow and friction on near-surface storm-relative helicity
| Autor: | Matthew D. Flournoy, Erik N. Rasmussen |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Journal of the Atmospheric Sciences. |
| ISSN: | 1520-0469 0022-4928 |
| DOI: | 10.1175/jas-d-20-0320.1 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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