A new Rossby wave-breaking interpretation of the North Atlantic Oscillation
This paper proposes the hypothesis that the low-frequency variability of the North Atlantic Oscillation (NAO) arises as a result of variations in the occurrence of upper-level Rossby wave-breaking events over the North Atlantic. These events lead to synoptic situations similar to midlatitude blockin...
| Main Authors: | , , , |
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| Format: | Journal article |
| Language: | English |
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2008
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| _version_ | 1826298819716841472 |
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| author | Woollings, T Hoskins, B Blackburn, M Berrisford, P |
| author_facet | Woollings, T Hoskins, B Blackburn, M Berrisford, P |
| author_sort | Woollings, T |
| collection | OXFORD |
| description | This paper proposes the hypothesis that the low-frequency variability of the North Atlantic Oscillation (NAO) arises as a result of variations in the occurrence of upper-level Rossby wave-breaking events over the North Atlantic. These events lead to synoptic situations similar to midlatitude blocking that are referred to as high-latitude blocking episodes. A positive NAO is envisaged as being a description of periods in which these episodes are infrequent and can be considered as a basic, unblocked situation. A negative NAO is a description of periods in which episodes occur frequently. A similar, but weaker, relationship exists between wave breaking over the Pacific and the west Pacific pattern. Evidence is given to support this hypothesis by using a two-dimensional potential-vorticity-based index to identify wave breaking at various latitudes. This is applied to Northern Hemisphere winter data from the 40-yr ECMWF Re-Analysis (ERA-40), and the events identified are then related to the NAO. Certain dynamical precursors are identified that appear to increase the likelihood of wave breaking. These suggest mechanisms by which variability in the tropical Pacific, and in the stratosphere, could affect the NAO. © 2008 American Meteorological Society. |
| first_indexed | 2024-03-07T04:52:37Z |
| format | Journal article |
| id | oxford-uuid:d57d0222-9fbf-458e-9246-baa5fdcb7a8f |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:52:37Z |
| publishDate | 2008 |
| record_format | dspace |
| spelling | oxford-uuid:d57d0222-9fbf-458e-9246-baa5fdcb7a8f2022-03-27T08:26:21ZA new Rossby wave-breaking interpretation of the North Atlantic OscillationJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:d57d0222-9fbf-458e-9246-baa5fdcb7a8fEnglishSymplectic Elements at Oxford2008Woollings, THoskins, BBlackburn, MBerrisford, PThis paper proposes the hypothesis that the low-frequency variability of the North Atlantic Oscillation (NAO) arises as a result of variations in the occurrence of upper-level Rossby wave-breaking events over the North Atlantic. These events lead to synoptic situations similar to midlatitude blocking that are referred to as high-latitude blocking episodes. A positive NAO is envisaged as being a description of periods in which these episodes are infrequent and can be considered as a basic, unblocked situation. A negative NAO is a description of periods in which episodes occur frequently. A similar, but weaker, relationship exists between wave breaking over the Pacific and the west Pacific pattern. Evidence is given to support this hypothesis by using a two-dimensional potential-vorticity-based index to identify wave breaking at various latitudes. This is applied to Northern Hemisphere winter data from the 40-yr ECMWF Re-Analysis (ERA-40), and the events identified are then related to the NAO. Certain dynamical precursors are identified that appear to increase the likelihood of wave breaking. These suggest mechanisms by which variability in the tropical Pacific, and in the stratosphere, could affect the NAO. © 2008 American Meteorological Society. |
| spellingShingle | Woollings, T Hoskins, B Blackburn, M Berrisford, P A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title | A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title_full | A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title_fullStr | A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title_full_unstemmed | A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title_short | A new Rossby wave-breaking interpretation of the North Atlantic Oscillation |
| title_sort | new rossby wave breaking interpretation of the north atlantic oscillation |
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