Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10
Wave-mean flow interaction is usually regarded as accounting for the origin of the Arctic Oscillation/Northern Hemisphere Annular Mode (AO/NAM). It is inferred that the combination of the local wave-mean flow interactions at the AO/NAM’s three regional centers of action on three important time scale...
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ftmdpi:oai:mdpi.com:/2073-4433/14/3/524/ 2023-08-20T04:04:58+02:00 Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 Sujie Liang Yanju Liu Yihui Ding agris 2023-03-09 application/pdf https://doi.org/10.3390/atmos14030524 EN eng Multidisciplinary Digital Publishing Institute Climatology https://dx.doi.org/10.3390/atmos14030524 https://creativecommons.org/licenses/by/4.0/ Atmosphere; Volume 14; Issue 3; Pages: 524 AO/NAM NAO PNA polar vortex ENSO Text 2023 ftmdpi https://doi.org/10.3390/atmos14030524 2023-08-01T09:11:03Z Wave-mean flow interaction is usually regarded as accounting for the origin of the Arctic Oscillation/Northern Hemisphere Annular Mode (AO/NAM). It is inferred that the combination of the local wave-mean flow interactions at the AO/NAM’s three regional centers of action on three important time scales contributes to the main behavior of the AO/NAM index. To discuss the variations of the AO/NAM indices on the three prominent time scales, we take the 2007/08 and 2009/10 winters as two comparative examples to analyze the local wave-mean flow interactions at the AO/NAM’s three centers. The following three facets are identified: (1) Synoptic-scale wave breakings in the North Atlantic can explain the variances of the AO/NAM index on a time scale of 10–20 days. In the 2007/08 winter, there were both cyclonic and anticyclonic synoptic wave breakings, while in the 2009/10 winter, cyclonic synoptic wave breaking was dominant, and the flow characteristics were strikingly similar to the blocking. (2) In the 2007/08 and 2009/10 winters, the signals of the AO/NAM indices on the time scale of 30–60 days are mainly from the interactions between the upward propagating quasi-stationary waves and the polar vortex in the stratosphere. (3) This work also demonstrates that the AO/NAM is linked to the El Niño–Southern Oscillation (ENSO) by the Pacific–North American pattern (PNA) on the winter mean time scale. In the 2007/08 (2009/10) winter, La Niña (El Niño) forced the Pacific jet to shift poleward (equatorward), in favor of weakening (enhancing) the polar waveguide; thus, the polar vortex became stronger (weaker), corresponding to the positive (negative) winter mean AO/NAM index. Text Arctic North Atlantic MDPI Open Access Publishing Arctic Pacific Atmosphere 14 3 524 |
institution |
Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
language |
English |
topic |
AO/NAM NAO PNA polar vortex ENSO |
spellingShingle |
AO/NAM NAO PNA polar vortex ENSO Sujie Liang Yanju Liu Yihui Ding Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
topic_facet |
AO/NAM NAO PNA polar vortex ENSO |
description |
Wave-mean flow interaction is usually regarded as accounting for the origin of the Arctic Oscillation/Northern Hemisphere Annular Mode (AO/NAM). It is inferred that the combination of the local wave-mean flow interactions at the AO/NAM’s three regional centers of action on three important time scales contributes to the main behavior of the AO/NAM index. To discuss the variations of the AO/NAM indices on the three prominent time scales, we take the 2007/08 and 2009/10 winters as two comparative examples to analyze the local wave-mean flow interactions at the AO/NAM’s three centers. The following three facets are identified: (1) Synoptic-scale wave breakings in the North Atlantic can explain the variances of the AO/NAM index on a time scale of 10–20 days. In the 2007/08 winter, there were both cyclonic and anticyclonic synoptic wave breakings, while in the 2009/10 winter, cyclonic synoptic wave breaking was dominant, and the flow characteristics were strikingly similar to the blocking. (2) In the 2007/08 and 2009/10 winters, the signals of the AO/NAM indices on the time scale of 30–60 days are mainly from the interactions between the upward propagating quasi-stationary waves and the polar vortex in the stratosphere. (3) This work also demonstrates that the AO/NAM is linked to the El Niño–Southern Oscillation (ENSO) by the Pacific–North American pattern (PNA) on the winter mean time scale. In the 2007/08 (2009/10) winter, La Niña (El Niño) forced the Pacific jet to shift poleward (equatorward), in favor of weakening (enhancing) the polar waveguide; thus, the polar vortex became stronger (weaker), corresponding to the positive (negative) winter mean AO/NAM index. |
format |
Text |
author |
Sujie Liang Yanju Liu Yihui Ding |
author_facet |
Sujie Liang Yanju Liu Yihui Ding |
author_sort |
Sujie Liang |
title |
Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
title_short |
Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
title_full |
Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
title_fullStr |
Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
title_full_unstemmed |
Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10 |
title_sort |
effects of wave-mean flow interaction on the multi-time-scale variability of the ao indices: a case study of winters 2007/08 and 2009/10 |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2023 |
url |
https://doi.org/10.3390/atmos14030524 |
op_coverage |
agris |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic North Atlantic |
genre_facet |
Arctic North Atlantic |
op_source |
Atmosphere; Volume 14; Issue 3; Pages: 524 |
op_relation |
Climatology https://dx.doi.org/10.3390/atmos14030524 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/atmos14030524 |
container_title |
Atmosphere |
container_volume |
14 |
container_issue |
3 |
container_start_page |
524 |
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1774715391376883712 |