Differences in El Niño response over the Southern Hemisphere

Southern Hemisphere (SH) circulation conditions during austral springs of ENSO events we examined. Based on previous knowledge that SST variations over the subtropical south-central Pacific (SSCP) region are linked to differences among El Niño (EN) events, a stratification of the springs associated...

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Publicado: 2004
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Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08948755_v17_n9_p1741_Vera
http://hdl.handle.net/20.500.12110/paper_08948755_v17_n9_p1741_Vera
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spelling paper:paper_08948755_v17_n9_p1741_Vera2023-06-08T15:47:51Z Differences in El Niño response over the Southern Hemisphere Atmospherics Climate change Heat convection Storms Thermal stratification Tropics Atmospheric changes Austral springs Intensification Southern Hemisphere Climatology air-sea interaction atmospheric circulation decadal variation El Nino intertropical convergence zone oceanic circulation sea surface temperature Southern Hemisphere Pacific Ocean Southern Hemisphere (SH) circulation conditions during austral springs of ENSO events we examined. Based on previous knowledge that SST variations over the subtropical south-central Pacific (SSCP) region are linked to differences among El Niño (EN) events, a stratification of the springs associated with EN events was performed according to SST conditions over the El Niño-3.4 sector and over the SSCP region. The EN events associated with cold conditions in the SSCP (WC) exhibit enhanced convection not only in the intertropical convergence zone over the central equatorial Pacific but also in the South Pacific convergence zone (SPCZ) extended southeastward into the subtropical regions. The resulting heating forcing intensifies a localized overturning cell, which is associated with an anomalous Rossby wave source in the central South Pacific extratropical region. Neither the Rossby wave source nor the associated wave pattern is evident during EN events associated with warm conditions in the SSCP and inactive SPCZ (WW). The basic features that characterize the differences in the EN response over the South Pacific can also be identified through the analysis of the SPCZ activity over the central South Pacific. The fact that variations in SPCZ activity lead SST anomaly changes in the SSCP would indicate that the differences in the EN response over the SH might be mainly driven by atmospheric changes, which induces extratropical SST anomalies. The differences in the circulation anomalies that characterize both types of EN response over the SH were further explored through the analysis of the activity of the three leading modes of circulation variability. The combined effect of the three leading patterns describes in some extent the intensification (weakening) of the cyclonic circulation anomaly observed over the southeastern Pacific in WC (WW), associated with an active (inactive) SPCZ. In particular, the interdecadal variability observed in the Pacific by many previous studies influences the circulation response to ENSO over the SH, mainly through changes in the activity of the SH annular mode. © 2004 American Meteorological Society. 2004 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08948755_v17_n9_p1741_Vera http://hdl.handle.net/20.500.12110/paper_08948755_v17_n9_p1741_Vera
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Atmospherics
Climate change
Heat convection
Storms
Thermal stratification
Tropics
Atmospheric changes
Austral springs
Intensification
Southern Hemisphere
Climatology
air-sea interaction
atmospheric circulation
decadal variation
El Nino
intertropical convergence zone
oceanic circulation
sea surface temperature
Southern Hemisphere
Pacific Ocean
spellingShingle Atmospherics
Climate change
Heat convection
Storms
Thermal stratification
Tropics
Atmospheric changes
Austral springs
Intensification
Southern Hemisphere
Climatology
air-sea interaction
atmospheric circulation
decadal variation
El Nino
intertropical convergence zone
oceanic circulation
sea surface temperature
Southern Hemisphere
Pacific Ocean
Differences in El Niño response over the Southern Hemisphere
topic_facet Atmospherics
Climate change
Heat convection
Storms
Thermal stratification
Tropics
Atmospheric changes
Austral springs
Intensification
Southern Hemisphere
Climatology
air-sea interaction
atmospheric circulation
decadal variation
El Nino
intertropical convergence zone
oceanic circulation
sea surface temperature
Southern Hemisphere
Pacific Ocean
description Southern Hemisphere (SH) circulation conditions during austral springs of ENSO events we examined. Based on previous knowledge that SST variations over the subtropical south-central Pacific (SSCP) region are linked to differences among El Niño (EN) events, a stratification of the springs associated with EN events was performed according to SST conditions over the El Niño-3.4 sector and over the SSCP region. The EN events associated with cold conditions in the SSCP (WC) exhibit enhanced convection not only in the intertropical convergence zone over the central equatorial Pacific but also in the South Pacific convergence zone (SPCZ) extended southeastward into the subtropical regions. The resulting heating forcing intensifies a localized overturning cell, which is associated with an anomalous Rossby wave source in the central South Pacific extratropical region. Neither the Rossby wave source nor the associated wave pattern is evident during EN events associated with warm conditions in the SSCP and inactive SPCZ (WW). The basic features that characterize the differences in the EN response over the South Pacific can also be identified through the analysis of the SPCZ activity over the central South Pacific. The fact that variations in SPCZ activity lead SST anomaly changes in the SSCP would indicate that the differences in the EN response over the SH might be mainly driven by atmospheric changes, which induces extratropical SST anomalies. The differences in the circulation anomalies that characterize both types of EN response over the SH were further explored through the analysis of the activity of the three leading modes of circulation variability. The combined effect of the three leading patterns describes in some extent the intensification (weakening) of the cyclonic circulation anomaly observed over the southeastern Pacific in WC (WW), associated with an active (inactive) SPCZ. In particular, the interdecadal variability observed in the Pacific by many previous studies influences the circulation response to ENSO over the SH, mainly through changes in the activity of the SH annular mode. © 2004 American Meteorological Society.
title Differences in El Niño response over the Southern Hemisphere
title_short Differences in El Niño response over the Southern Hemisphere
title_full Differences in El Niño response over the Southern Hemisphere
title_fullStr Differences in El Niño response over the Southern Hemisphere
title_full_unstemmed Differences in El Niño response over the Southern Hemisphere
title_sort differences in el niño response over the southern hemisphere
publishDate 2004
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08948755_v17_n9_p1741_Vera
http://hdl.handle.net/20.500.12110/paper_08948755_v17_n9_p1741_Vera
_version_ 1768544737925529600