Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO
This study examines the linkages between leading patterns of interannual sea level pressure (SLP) variability over the extratropical Pacific (20°-60°N) and the eastern Pacific (EP) and central Pacific (CP) types of El Niño-Southern Oscillation (ENSO). The first empirical orthogonal function (EOF) mo...
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ftcdlib:oai:escholarship.org/ark:/13030/qt33c3t886 2023-05-15T13:15:09+02:00 Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO Yu, JY Kim, ST 708 - 720 2011-02-01 application/pdf https://escholarship.org/uc/item/33c3t886 unknown eScholarship, University of California qt33c3t886 https://escholarship.org/uc/item/33c3t886 CC-BY CC-BY Journal of Climate, vol 24, iss 3 Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering article 2011 ftcdlib 2021-10-25T17:15:37Z This study examines the linkages between leading patterns of interannual sea level pressure (SLP) variability over the extratropical Pacific (20°-60°N) and the eastern Pacific (EP) and central Pacific (CP) types of El Niño-Southern Oscillation (ENSO). The first empirical orthogonal function (EOF) mode of the extratropical SLP anomalies represents variations of the Aleutian low, and the second EOF mode represents the North Pacific Oscillation (NPO) and is characterized by a meridional SLP anomaly dipole with a nodal point near 50°N. It is shown that a fraction of the first SLP mode can be excited by both the EP and CP types of ENSO. The SLP response to the EP type is stronger and more immediate. The tropical-extratropical teleconnection appears to act more slowly for the CP ENSO. During the decay phase of EP events, the associated extratropical SLP anomalies shift from the first SLP mode to the second SLP mode. As the second SLP mode grows, subtropical SST anomalies are induced beneath via surface heat flux anomalies. The SST anomalies persist after the peak in strength of the second SLP mode, likely because of the seasonal footprinting mechanism, and lead to the development of the CP type of ENSO. This study shows that the CP ENSO is an extratropically excited mode of tropical Pacific variability and also suggests that the decay of an EP type of ENSO can lead to the onset of a CP type of ENSO with the aid of the NPO. This extratropical linking mechanism appears to be at work during the 1972, 1982, and 1997 strong El Niño events, which were all EP events and were all followed by strong CP La Niña events after the NPO was excited in the extratropics. This study concludes that extratropical SLP variations play an important role in exciting the CP type of ENSO and in linking the transitions from the EP to CP events. © 2011 American Meteorological Society. Article in Journal/Newspaper aleutian low University of California: eScholarship Pacific |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
spellingShingle |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering Yu, JY Kim, ST Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
topic_facet |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
description |
This study examines the linkages between leading patterns of interannual sea level pressure (SLP) variability over the extratropical Pacific (20°-60°N) and the eastern Pacific (EP) and central Pacific (CP) types of El Niño-Southern Oscillation (ENSO). The first empirical orthogonal function (EOF) mode of the extratropical SLP anomalies represents variations of the Aleutian low, and the second EOF mode represents the North Pacific Oscillation (NPO) and is characterized by a meridional SLP anomaly dipole with a nodal point near 50°N. It is shown that a fraction of the first SLP mode can be excited by both the EP and CP types of ENSO. The SLP response to the EP type is stronger and more immediate. The tropical-extratropical teleconnection appears to act more slowly for the CP ENSO. During the decay phase of EP events, the associated extratropical SLP anomalies shift from the first SLP mode to the second SLP mode. As the second SLP mode grows, subtropical SST anomalies are induced beneath via surface heat flux anomalies. The SST anomalies persist after the peak in strength of the second SLP mode, likely because of the seasonal footprinting mechanism, and lead to the development of the CP type of ENSO. This study shows that the CP ENSO is an extratropically excited mode of tropical Pacific variability and also suggests that the decay of an EP type of ENSO can lead to the onset of a CP type of ENSO with the aid of the NPO. This extratropical linking mechanism appears to be at work during the 1972, 1982, and 1997 strong El Niño events, which were all EP events and were all followed by strong CP La Niña events after the NPO was excited in the extratropics. This study concludes that extratropical SLP variations play an important role in exciting the CP type of ENSO and in linking the transitions from the EP to CP events. © 2011 American Meteorological Society. |
format |
Article in Journal/Newspaper |
author |
Yu, JY Kim, ST |
author_facet |
Yu, JY Kim, ST |
author_sort |
Yu, JY |
title |
Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
title_short |
Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
title_full |
Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
title_fullStr |
Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
title_full_unstemmed |
Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO |
title_sort |
relationships between extratropical sea level pressure variations and the central pacific and eastern pacific types of enso |
publisher |
eScholarship, University of California |
publishDate |
2011 |
url |
https://escholarship.org/uc/item/33c3t886 |
op_coverage |
708 - 720 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
aleutian low |
genre_facet |
aleutian low |
op_source |
Journal of Climate, vol 24, iss 3 |
op_relation |
qt33c3t886 https://escholarship.org/uc/item/33c3t886 |
op_rights |
CC-BY |
op_rightsnorm |
CC-BY |
_version_ |
1766267171391930368 |