Effectiveness of the Bjerknes stability index in representing ocean dynamics
The El Nio-Southern Oscillation (ENSO) is a naturally occurring coupled phenomenon originating in the tropical Pacific Ocean that relies on oceanatmosphere feedbacks. The Bjerknes stability index (BJ index), derived from the mixed-layer heat budget, aims to quantify the ENSO feedback process in orde...
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Online Access: | https://doi.org/10.1007/s00382-014-2062-3 http://ecite.utas.edu.au/88909 |
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ftunivtasecite:oai:ecite.utas.edu.au:88909 2023-05-15T18:18:38+02:00 Effectiveness of the Bjerknes stability index in representing ocean dynamics Graham, FS Brown, JN Langlais, C Marsland, SJ Wittenberg, AT Holbrook, NJ 2014 https://doi.org/10.1007/s00382-014-2062-3 http://ecite.utas.edu.au/88909 en eng Springer-Verlag http://dx.doi.org/10.1007/s00382-014-2062-3 Graham, FS and Brown, JN and Langlais, C and Marsland, SJ and Wittenberg, AT and Holbrook, NJ, Effectiveness of the Bjerknes stability index in representing ocean dynamics, Climate Dynamics, 43, (9-10) pp. 2399-2414. ISSN 1432-0894 (2014) [Refereed Article] http://ecite.utas.edu.au/88909 Earth Sciences Oceanography Physical Oceanography Refereed Article PeerReviewed 2014 ftunivtasecite https://doi.org/10.1007/s00382-014-2062-3 2019-12-13T21:52:31Z The El Nio-Southern Oscillation (ENSO) is a naturally occurring coupled phenomenon originating in the tropical Pacific Ocean that relies on oceanatmosphere feedbacks. The Bjerknes stability index (BJ index), derived from the mixed-layer heat budget, aims to quantify the ENSO feedback process in order to explore the linear stability properties of ENSO. More recently, the BJ index has been used for model intercomparisons, particularly for the CMIP3 and CMIP5 models. This study investigates the effectiveness of the BJ index in representing the key ENSO ocean feedbacksnamely the thermocline, zonal advective, and Ekman feedbacksby evaluating the amplitudes and phases of the BJ index terms against the corresponding heat budget terms from which they were derived. The output from Australian Community Climate and Earth System Simulator Ocean Model (a global ocean/sea ice flux-forced model) is used to calculate the heat budget in the equatorial Pacific. Through the model evaluation process, the robustness of the BJ index terms are tested. We find that the BJ index overestimates the relative importance of the thermocline feedback to the zonal advective feedback when compared with the corresponding terms from the heat budget equation. The assumption of linearity between variables in the BJ index formulation is the primary reason for these differences. Our results imply that a model intercomparison relying on the BJ index to explain ENSO behavior is not necessarily an accurate quantification of dynamical differences between models that are inherently nonlinear. For these reasons, the BJ index may not fully explain underpinning changes in ENSO under global warming scenarios. Article in Journal/Newspaper Sea ice eCite UTAS (University of Tasmania) Pacific Climate Dynamics 43 9-10 2399 2414 |
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Open Polar |
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eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Physical Oceanography |
spellingShingle |
Earth Sciences Oceanography Physical Oceanography Graham, FS Brown, JN Langlais, C Marsland, SJ Wittenberg, AT Holbrook, NJ Effectiveness of the Bjerknes stability index in representing ocean dynamics |
topic_facet |
Earth Sciences Oceanography Physical Oceanography |
description |
The El Nio-Southern Oscillation (ENSO) is a naturally occurring coupled phenomenon originating in the tropical Pacific Ocean that relies on oceanatmosphere feedbacks. The Bjerknes stability index (BJ index), derived from the mixed-layer heat budget, aims to quantify the ENSO feedback process in order to explore the linear stability properties of ENSO. More recently, the BJ index has been used for model intercomparisons, particularly for the CMIP3 and CMIP5 models. This study investigates the effectiveness of the BJ index in representing the key ENSO ocean feedbacksnamely the thermocline, zonal advective, and Ekman feedbacksby evaluating the amplitudes and phases of the BJ index terms against the corresponding heat budget terms from which they were derived. The output from Australian Community Climate and Earth System Simulator Ocean Model (a global ocean/sea ice flux-forced model) is used to calculate the heat budget in the equatorial Pacific. Through the model evaluation process, the robustness of the BJ index terms are tested. We find that the BJ index overestimates the relative importance of the thermocline feedback to the zonal advective feedback when compared with the corresponding terms from the heat budget equation. The assumption of linearity between variables in the BJ index formulation is the primary reason for these differences. Our results imply that a model intercomparison relying on the BJ index to explain ENSO behavior is not necessarily an accurate quantification of dynamical differences between models that are inherently nonlinear. For these reasons, the BJ index may not fully explain underpinning changes in ENSO under global warming scenarios. |
format |
Article in Journal/Newspaper |
author |
Graham, FS Brown, JN Langlais, C Marsland, SJ Wittenberg, AT Holbrook, NJ |
author_facet |
Graham, FS Brown, JN Langlais, C Marsland, SJ Wittenberg, AT Holbrook, NJ |
author_sort |
Graham, FS |
title |
Effectiveness of the Bjerknes stability index in representing ocean dynamics |
title_short |
Effectiveness of the Bjerknes stability index in representing ocean dynamics |
title_full |
Effectiveness of the Bjerknes stability index in representing ocean dynamics |
title_fullStr |
Effectiveness of the Bjerknes stability index in representing ocean dynamics |
title_full_unstemmed |
Effectiveness of the Bjerknes stability index in representing ocean dynamics |
title_sort |
effectiveness of the bjerknes stability index in representing ocean dynamics |
publisher |
Springer-Verlag |
publishDate |
2014 |
url |
https://doi.org/10.1007/s00382-014-2062-3 http://ecite.utas.edu.au/88909 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
http://dx.doi.org/10.1007/s00382-014-2062-3 Graham, FS and Brown, JN and Langlais, C and Marsland, SJ and Wittenberg, AT and Holbrook, NJ, Effectiveness of the Bjerknes stability index in representing ocean dynamics, Climate Dynamics, 43, (9-10) pp. 2399-2414. ISSN 1432-0894 (2014) [Refereed Article] http://ecite.utas.edu.au/88909 |
op_doi |
https://doi.org/10.1007/s00382-014-2062-3 |
container_title |
Climate Dynamics |
container_volume |
43 |
container_issue |
9-10 |
container_start_page |
2399 |
op_container_end_page |
2414 |
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1766195277893468160 |