Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex
Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological...
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American Meteorological Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/114586 https://orcid.org/0000-0002-6716-1576 |
| _version_ | 1811096811053514752 |
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| author | Byrne, Nicholas J. Shepherd, Theodore G. Woollings, Tim Plumb, R. Alan |
| 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 Byrne, Nicholas J. Shepherd, Theodore G. Woollings, Tim Plumb, R. Alan |
| author_sort | Byrne, Nicholas J. |
| collection | MIT |
| description | Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological seasonal cycle and long-term trends, and the assumption of stationary statistics is only an approximation. The variability of the Southern Hemisphere zonal-mean circulation in the period encompassing late spring and summer is an important climate phenomenon and has been the subject of numerous studies. It is shown here, using reanalysis data, that this variability is rendered highly nonstationary by the organizing influence of the seasonal breakdown of the stratospheric polar vortex, which breaks time symmetry. It is argued that the zonal-mean tropospheric circulation variability during this period is best viewed as interannual variability in the transition between the springtime and summertime regimes induced by variability in the vortex breakdown. In particular, the apparent long-term poleward jet shift during the early-summer season can be more simply understood as a delay in the equatorward shift associated with this regime transition. The implications of such a perspective for various open questions are discussed. Keywords: Antarctic Oscillation; Stratosphere-troposphere coupling; Climate classification/regimes; Seasonal forecasting; Anomalies; Ozone |
| first_indexed | 2024-09-23T16:49:22Z |
| format | Article |
| id | mit-1721.1/114586 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:49:22Z |
| publishDate | 2018 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1145862024-05-15T02:13:24Z Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex Byrne, Nicholas J. Shepherd, Theodore G. Woollings, Tim Plumb, R. Alan Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Plumb, Raymond Alan Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological seasonal cycle and long-term trends, and the assumption of stationary statistics is only an approximation. The variability of the Southern Hemisphere zonal-mean circulation in the period encompassing late spring and summer is an important climate phenomenon and has been the subject of numerous studies. It is shown here, using reanalysis data, that this variability is rendered highly nonstationary by the organizing influence of the seasonal breakdown of the stratospheric polar vortex, which breaks time symmetry. It is argued that the zonal-mean tropospheric circulation variability during this period is best viewed as interannual variability in the transition between the springtime and summertime regimes induced by variability in the vortex breakdown. In particular, the apparent long-term poleward jet shift during the early-summer season can be more simply understood as a delay in the equatorward shift associated with this regime transition. The implications of such a perspective for various open questions are discussed. Keywords: Antarctic Oscillation; Stratosphere-troposphere coupling; Climate classification/regimes; Seasonal forecasting; Anomalies; Ozone 2018-04-06T14:24:35Z 2018-04-06T14:24:35Z 2017-08 2017-05 2018-03-30T17:31:43Z Article http://purl.org/eprint/type/JournalArticle 0894-8755 1520-0442 http://hdl.handle.net/1721.1/114586 Byrne, Nicholas J. et al. “Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex.” Journal of Climate 30, 18 (September 2017): 7125–7139 © 2017 American Meteorological Society https://orcid.org/0000-0002-6716-1576 http://dx.doi.org/10.1175/JCLI-D-17-0097.1 Journal of Climate 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 Meteorological Society American Meteorological Society |
| spellingShingle | Byrne, Nicholas J. Shepherd, Theodore G. Woollings, Tim Plumb, R. Alan Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title | Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title_full | Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title_fullStr | Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title_full_unstemmed | Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title_short | Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex |
| title_sort | nonstationarity in southern hemisphere climate variability associated with the seasonal breakdown of the stratospheric polar vortex |
| url | http://hdl.handle.net/1721.1/114586 https://orcid.org/0000-0002-6716-1576 |
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