Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence
We numerically investigate single-layer shallow-water beta-plane quasi-geostrophic turbulence in a doubly periodic domain with emphasis onwavenumber-frequency spectra.We conduct a broad parameter sweep, varying the deformation radius (Ld ), the narrow-band forcing wavenumber (kf), and the meridional...
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American Institute of Physics (AIP)
2018
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| Online Access: | http://hdl.handle.net/1721.1/118342 https://orcid.org/0000-0003-3589-5249 |
| _version_ | 1811088557088964608 |
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| author | Morten, A. J. Arbic, B. K. Flierl, Glenn Richard |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Morten, A. J. Arbic, B. K. Flierl, Glenn Richard |
| author_sort | Morten, A. J. |
| collection | MIT |
| description | We numerically investigate single-layer shallow-water beta-plane quasi-geostrophic turbulence in a doubly periodic domain with emphasis onwavenumber-frequency spectra.We conduct a broad parameter sweep, varying the deformation radius (Ld ), the narrow-band forcing wavenumber (kf), and the meridional gradient of the Coriolis parameter (β). Out of 54 simulations we present ten in detail spanning slowly propagating vortices to strong jets. We define a nondimensional parameter γβin terms of β, Ld, and the energy injection rate. The moderately low γβcase is characterized by westward propagating coherent vortices and zonal wavenumber-frequency spectra dominated by a nondispersive line (NDL) corresponding to uniform propagation at or near the long-wave Rossby speed. The moderately high γβcase is characterized by jets, and the NDL persists even when there are no coherent vortices. The jets have large meridional excursions (meanders) that propagate westward nearly uniformly at a speed slower than the long-wave Rossby speed. Also at moderately high γβ, a second dispersion relation appears, roughly corresponding to linear waves on a zonal potential vorticity (PV) staircase. At very high γβ, during the slow evolution to a PV staircase, the structure of the linear waves is altered by the small perturbations to a constant potential vorticity gradient. A simple model treating the small perturbation as a sinusoid accurately predicts the meridional wavenumber-frequency spectra in the very high γβsimulations. |
| first_indexed | 2024-09-23T14:04:02Z |
| format | Article |
| id | mit-1721.1/118342 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T14:04:02Z |
| publishDate | 2018 |
| publisher | American Institute of Physics (AIP) |
| record_format | dspace |
| spelling | mit-1721.1/1183422022-10-01T18:58:54Z Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence Morten, A. J. Arbic, B. K. Flierl, Glenn Richard Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Flierl, Glenn Richard We numerically investigate single-layer shallow-water beta-plane quasi-geostrophic turbulence in a doubly periodic domain with emphasis onwavenumber-frequency spectra.We conduct a broad parameter sweep, varying the deformation radius (Ld ), the narrow-band forcing wavenumber (kf), and the meridional gradient of the Coriolis parameter (β). Out of 54 simulations we present ten in detail spanning slowly propagating vortices to strong jets. We define a nondimensional parameter γβin terms of β, Ld, and the energy injection rate. The moderately low γβcase is characterized by westward propagating coherent vortices and zonal wavenumber-frequency spectra dominated by a nondispersive line (NDL) corresponding to uniform propagation at or near the long-wave Rossby speed. The moderately high γβcase is characterized by jets, and the NDL persists even when there are no coherent vortices. The jets have large meridional excursions (meanders) that propagate westward nearly uniformly at a speed slower than the long-wave Rossby speed. Also at moderately high γβ, a second dispersion relation appears, roughly corresponding to linear waves on a zonal potential vorticity (PV) staircase. At very high γβ, during the slow evolution to a PV staircase, the structure of the linear waves is altered by the small perturbations to a constant potential vorticity gradient. A simple model treating the small perturbation as a sinusoid accurately predicts the meridional wavenumber-frequency spectra in the very high γβsimulations. National Science Foundation (U.S.) (Grant OCE-0960826) 2018-10-03T17:40:35Z 2018-10-03T17:40:35Z 2017-10 2017-02 2018-09-24T14:13:13Z Article http://purl.org/eprint/type/JournalArticle 1070-6631 1089-7666 http://hdl.handle.net/1721.1/118342 Morten, A. J. et al. “Wavenumber-Frequency Analysis of Single-Layer Shallow-Water Beta-Plane Quasi-Geostrophic Turbulence.” Physics of Fluids 29, 10 (October 2017): 106602 © 2017 American Institute of Physics (AIP) https://orcid.org/0000-0003-3589-5249 http://dx.doi.org/10.1063/1.5003846 Physics of Fluids Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Institute of Physics (AIP) Other univ. web domain |
| spellingShingle | Morten, A. J. Arbic, B. K. Flierl, Glenn Richard Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title | Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title_full | Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title_fullStr | Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title_full_unstemmed | Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title_short | Wavenumber-frequency analysis of single-layer shallow-water beta-plane quasi-geostrophic turbulence |
| title_sort | wavenumber frequency analysis of single layer shallow water beta plane quasi geostrophic turbulence |
| url | http://hdl.handle.net/1721.1/118342 https://orcid.org/0000-0003-3589-5249 |
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