Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation

We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) base...

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Autores principales:	Renom Molina, Madeleine, Rusticucci, Matilde
Publicado:	2011
Materias:	1976 climate shift ENSO Extreme temperature events Multidecadal variability SAM Uruguay-Southeastern South America air temperature airflow annual variation anticyclone atmospheric circulation barotropic motion cold air El Nino-Southern Oscillation extreme event summer vortex flow winter Atlantic Ocean Atlantic Ocean (South) Uruguay
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09307575_v37_n11-12_p2471_Renom http://hdl.handle.net/20.500.12110/paper_09307575_v37_n11-12_p2471_Renom
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_09307575_v37_n11-12_p2471_Renom
record_format	dspace
spelling	paper:paper_09307575_v37_n11-12_p2471_Renom2023-06-08T15:52:40Z Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation Renom Molina, Madeleine Rusticucci, Matilde 1976 climate shift ENSO Extreme temperature events Multidecadal variability SAM Uruguay-Southeastern South America air temperature airflow annual variation anticyclone atmospheric circulation barotropic motion cold air El Nino-Southern Oscillation extreme event summer vortex flow winter Atlantic Ocean Atlantic Ocean (South) Uruguay We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Niño phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Niño connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Niño evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation. © 2011 Springer-Verlag. Fil:Renom, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Rusticucci, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09307575_v37_n11-12_p2471_Renom http://hdl.handle.net/20.500.12110/paper_09307575_v37_n11-12_p2471_Renom
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	1976 climate shift ENSO Extreme temperature events Multidecadal variability SAM Uruguay-Southeastern South America air temperature airflow annual variation anticyclone atmospheric circulation barotropic motion cold air El Nino-Southern Oscillation extreme event summer vortex flow winter Atlantic Ocean Atlantic Ocean (South) Uruguay
spellingShingle	1976 climate shift ENSO Extreme temperature events Multidecadal variability SAM Uruguay-Southeastern South America air temperature airflow annual variation anticyclone atmospheric circulation barotropic motion cold air El Nino-Southern Oscillation extreme event summer vortex flow winter Atlantic Ocean Atlantic Ocean (South) Uruguay Renom Molina, Madeleine Rusticucci, Matilde Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
topic_facet	1976 climate shift ENSO Extreme temperature events Multidecadal variability SAM Uruguay-Southeastern South America air temperature airflow annual variation anticyclone atmospheric circulation barotropic motion cold air El Nino-Southern Oscillation extreme event summer vortex flow winter Atlantic Ocean Atlantic Ocean (South) Uruguay
description	We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Niño phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Niño connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Niño evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation. © 2011 Springer-Verlag.
author	Renom Molina, Madeleine Rusticucci, Matilde
author_facet	Renom Molina, Madeleine Rusticucci, Matilde
author_sort	Renom Molina, Madeleine
title	Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
title_short	Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
title_full	Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
title_fullStr	Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
title_full_unstemmed	Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
title_sort	multidecadal changes in the relationship between extreme temperature events in uruguay and the general atmospheric circulation
publishDate	2011
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09307575_v37_n11-12_p2471_Renom http://hdl.handle.net/20.500.12110/paper_09307575_v37_n11-12_p2471_Renom
work_keys_str_mv	AT renommolinamadeleine multidecadalchangesintherelationshipbetweenextremetemperatureeventsinuruguayandthegeneralatmosphericcirculation AT rusticuccimatilde multidecadalchangesintherelationshipbetweenextremetemperatureeventsinuruguayandthegeneralatmosphericcirculation
_version_	1768546682701611008

Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation

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