Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal?
International audience In this paper, we investigate the atmospheric excitation of polar motion (PM) associated with the El Niño-Southern Oscillation (ENSO) phenomenon. ENSO effects on length-of-day due to changes in the axial component of atmospheric angular momentum (AAM) have long been recognized...
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ftunivparis:oai:HAL:insu-03605271v1 2024-05-19T07:29:50+00:00 Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? Marcus, Steven L. de Viron, Olivier Dickey, Jean O. Institut de Physique du Globe de Paris (IPGP) Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) 2010 https://insu.hal.science/insu-03605271 https://insu.hal.science/insu-03605271/document https://insu.hal.science/insu-03605271/file/Journal%20of%20Geophysical%20Research%20Solid%20Earth%20-%202010%20-%20Marcus%20-%20Interannual%20atmospheric%20torque%20and%20El%20Ni%20o%20Southern.pdf https://doi.org/10.1029/2010JB007524 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/2010JB007524 insu-03605271 https://insu.hal.science/insu-03605271 https://insu.hal.science/insu-03605271/document https://insu.hal.science/insu-03605271/file/Journal%20of%20Geophysical%20Research%20Solid%20Earth%20-%202010%20-%20Marcus%20-%20Interannual%20atmospheric%20torque%20and%20El%20Ni%20o%20Southern.pdf BIBCODE: 2010JGRB.11512409M doi:10.1029/2010JB007524 http://hal.archives-ouvertes.fr/licences/copyright/ info:eu-repo/semantics/OpenAccess ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://insu.hal.science/insu-03605271 Journal of Geophysical Research : Solid Earth, 2010, 115, ⟨10.1029/2010JB007524⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2010 ftunivparis https://doi.org/10.1029/2010JB007524 2024-04-30T02:58:07Z International audience In this paper, we investigate the atmospheric excitation of polar motion (PM) associated with the El Niño-Southern Oscillation (ENSO) phenomenon. ENSO effects on length-of-day due to changes in the axial component of atmospheric angular momentum (AAM) have long been recognized, but identification of PM excitation with ENSO-induced equatorial AAM anomalies has proved more elusive. Here we use an appropriately modified form of the inverted barometer (IB) assumption to study ENSO-related atmospheric torques arising from pressure loading on the Earth's ellipsoidal bulge and mountains and from frictional wind stress over the Earth's land- and ocean-covered surface. The resulting dissipation torques, which accommodate adjustment of the oceanic mass distribution to time-variable atmospheric loading, are found to be small. The ellipsoidal torques have the largest amplitude, reflecting the order-of-magnitude discrepancy between the height departures of the Earth's bulge (∼20 km) and its surface orography (∼2 km). Because of relatively uniform pressure covariances with the Southern Oscillation Index over the continents for the largely land-based X component and the uniform IB response for the largely ocean-based Y component; however, the ENSO-related PM excitation arising from the ellipsoidal torques is reduced to an amplitude comparable with the sum of regional mountain torques from the individual continents. The largest of these are generated over Asia and Antarctica, arising from efficient coupling of ENSO-related surface pressure anomalies with large-scale orographic features. The geometrical mitigation of the ellipsoidal torques, classically expected to dominate equatorial AAM forcing, accounts for the lack of a detectable atmosphere-driven polar motion response to ENSO. Article in Journal/Newspaper Antarc* Antarctica Université de Paris: Portail HAL Journal of Geophysical Research 115 B12 |
institution |
Open Polar |
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Université de Paris: Portail HAL |
op_collection_id |
ftunivparis |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Marcus, Steven L. de Viron, Olivier Dickey, Jean O. Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience In this paper, we investigate the atmospheric excitation of polar motion (PM) associated with the El Niño-Southern Oscillation (ENSO) phenomenon. ENSO effects on length-of-day due to changes in the axial component of atmospheric angular momentum (AAM) have long been recognized, but identification of PM excitation with ENSO-induced equatorial AAM anomalies has proved more elusive. Here we use an appropriately modified form of the inverted barometer (IB) assumption to study ENSO-related atmospheric torques arising from pressure loading on the Earth's ellipsoidal bulge and mountains and from frictional wind stress over the Earth's land- and ocean-covered surface. The resulting dissipation torques, which accommodate adjustment of the oceanic mass distribution to time-variable atmospheric loading, are found to be small. The ellipsoidal torques have the largest amplitude, reflecting the order-of-magnitude discrepancy between the height departures of the Earth's bulge (∼20 km) and its surface orography (∼2 km). Because of relatively uniform pressure covariances with the Southern Oscillation Index over the continents for the largely land-based X component and the uniform IB response for the largely ocean-based Y component; however, the ENSO-related PM excitation arising from the ellipsoidal torques is reduced to an amplitude comparable with the sum of regional mountain torques from the individual continents. The largest of these are generated over Asia and Antarctica, arising from efficient coupling of ENSO-related surface pressure anomalies with large-scale orographic features. The geometrical mitigation of the ellipsoidal torques, classically expected to dominate equatorial AAM forcing, accounts for the lack of a detectable atmosphere-driven polar motion response to ENSO. |
author2 |
Institut de Physique du Globe de Paris (IPGP) Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Marcus, Steven L. de Viron, Olivier Dickey, Jean O. |
author_facet |
Marcus, Steven L. de Viron, Olivier Dickey, Jean O. |
author_sort |
Marcus, Steven L. |
title |
Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
title_short |
Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
title_full |
Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
title_fullStr |
Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
title_full_unstemmed |
Interannual atmospheric torque and El Niño-Southern Oscillation: Where is the polar motion signal? |
title_sort |
interannual atmospheric torque and el niño-southern oscillation: where is the polar motion signal? |
publisher |
HAL CCSD |
publishDate |
2010 |
url |
https://insu.hal.science/insu-03605271 https://insu.hal.science/insu-03605271/document https://insu.hal.science/insu-03605271/file/Journal%20of%20Geophysical%20Research%20Solid%20Earth%20-%202010%20-%20Marcus%20-%20Interannual%20atmospheric%20torque%20and%20El%20Ni%20o%20Southern.pdf https://doi.org/10.1029/2010JB007524 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://insu.hal.science/insu-03605271 Journal of Geophysical Research : Solid Earth, 2010, 115, ⟨10.1029/2010JB007524⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2010JB007524 insu-03605271 https://insu.hal.science/insu-03605271 https://insu.hal.science/insu-03605271/document https://insu.hal.science/insu-03605271/file/Journal%20of%20Geophysical%20Research%20Solid%20Earth%20-%202010%20-%20Marcus%20-%20Interannual%20atmospheric%20torque%20and%20El%20Ni%20o%20Southern.pdf BIBCODE: 2010JGRB.11512409M doi:10.1029/2010JB007524 |
op_rights |
http://hal.archives-ouvertes.fr/licences/copyright/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/2010JB007524 |
container_title |
Journal of Geophysical Research |
container_volume |
115 |
container_issue |
B12 |
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1799481742225047552 |