dc.contributor.author | Díaz-Durán, A | |
dc.contributor.author | Serrano, E | |
dc.contributor.author | Ayarzagüena, B | |
dc.contributor.author | Abalos, M | |
dc.contributor.author | de la Cámara, A | |
dc.date.accessioned | 2017-01-11T10:00:50Z | |
dc.date.issued | 2017-01-20 | |
dc.description.abstract | The dynamical variability of the boreal stratospheric polar vortex has been usually analysed considering the
extended winter as a whole or only focusing on December, January and February. Yet recent studies have
found intra-seasonal differences in the boreal stratospheric dynamics. In this study, the intra-seasonal
variability of anomalous wave activity preceding polar vortex extremes in the Northern Hemisphere is
examined using ERA-Interim reanalysis data. Weak (WPV) and strong (SPV) polar vortex events are grouped
into early, mid- or late winter sub-periods depending on the onset date. Overall, the strongest (weakest) wave-
activity anomalies preceding polar vortex extremes are found in mid- (early) winter. Most of WPV
(SPV) events in early winter occur under the influence of east (west) phase of the Quasi-Biennial Oscillation
20 (QBO) and an enhancement (inhibition) of wavenumber-1 wave activity (WN1). Mid- and late winter WPV
21 events are preceded by a strong vortex and an enhancement of WN1 and WN2, but the spatial structure of the
anomalous wave activity and the phase of the QBO are different. Prior to mid-winter WPVs the enhancement
of WN2 is related to the predominance of La Niña and linked to blockings over Siberia. Mid-winter SPV
events show a negative phase of the Pacific-North America pattern that inhibits WN1 injected into the
stratosphere. This study suggests that dynamical features preceding extreme polar vortex events in mid-winter
should not be generalized to other winter sub-periods. | en_GB |
dc.description.sponsorship | This
work was supported by the Spanish Ministry of Economy and Competitiveness (grant number CGL2012-
34997). BA is supported by the Natural Environment Research Council (grant number NE/M006123/1). MA
acknowledges funding from the NASA ACMAP program. | en_GB |
dc.identifier.citation | First Online: 20 January 2017 | en_GB |
dc.identifier.doi | 10.1007/s00382-017-3524-1 | |
dc.identifier.uri | http://hdl.handle.net/10871/25157 | |
dc.language.iso | en | en_GB |
dc.publisher | Springer Verlag | en_GB |
dc.relation.source | The ERA-Interim reanalysis data were obtained
online at http://data-portal.ecmwf.int/data/d/interim full moda/. ENSO and QBO indices have been taken from
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears_ERSSTv3b.shtml and
http://www.cpc.noaa.gov/data/indices/, respectively. | en_GB |
dc.rights.embargoreason | Publisher's policy. | en_GB |
dc.subject | Intra-seasonal variability | en_GB |
dc.subject | wave activity | en_GB |
dc.subject | stratospheric polar vortex extremes | en_GB |
dc.subject | tropospheric precursors | en_GB |
dc.subject | tropospheric forcing | en_GB |
dc.subject | stratospheric dynamics | en_GB |
dc.title | Intra-seasonal variability of extreme boreal stratospheric polar vortex events and their precursors | en_GB |
dc.type | Article | en_GB |
dc.identifier.issn | 0930-7575 | |
dc.description | This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record. | |
dc.identifier.journal | Climate Dynamics | en_GB |