Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America

This paper describes the large-scale atmospheric circulation associated with persistent generalized frosts (GFs; at least 75% of the stations report frosts) in the east-central region of Argentina known as the Wet Pampa. The GF events are grouped according to their persistence, and NCEP-NCAR reanaly...

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Autores principales: Müller, Gabriela Viviana, Berri, Guillermo Jorge
Publicado: 2007
Materias:
Advection
Frost effects
Jets
Wind
Anticyclone
Atmospheric circulation
Generalized frosts
Rossby waves
Atmospheric movements
advection
anomaly
atmospheric circulation
cold air
frost
meridional circulation
Rossby wave
wave propagation
Argentina
South America
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00270644_v135_n4_p1268_Muller
http://hdl.handle.net/20.500.12110/paper_00270644_v135_n4_p1268_Muller
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00270644_v135_n4_p1268_Muller
record_format dspace
spelling paper:paper_00270644_v135_n4_p1268_Muller2023-06-08T14:54:07Z Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America Müller, Gabriela Viviana Berri, Guillermo Jorge Advection Frost effects Jets Wind Anticyclone Atmospheric circulation Generalized frosts Rossby waves Atmospheric movements advection anomaly atmospheric circulation cold air frost meridional circulation Rossby wave wave propagation Argentina South America This paper describes the large-scale atmospheric circulation associated with persistent generalized frosts (GFs; at least 75% of the stations report frosts) in the east-central region of Argentina known as the Wet Pampa. The GF events are grouped according to their persistence, and NCEP-NCAR reanalysis data are used to create daily composites of mass and wind field anomalies during the 1961-90 winters. The GFs are caused by an anticyclonic anomaly that enters South America, generating southerly wind anomalies and cold air advection that are strengthened by the meridional layout of a cyclonic anomaly over the South Atlantic Ocean. In the case of the more persistent events the wind anomaly grows during the previous days and becomes quasi-stationary. Also, the study identifies at 250 hPa a double train of eastward-moving Rossby waves along the subtropical and subpolar latitudes, respectively, of the Southern Hemisphere. The layout of both wave trains favors the development of an intense southerly wind anomaly in the entire southern cone of the continent. On the other hand, the propagation pattern during the less persistent GFs shows only one arc-shaped Rossby wave train that reaches South America, and then propagates northeastward. Additionally, there is a subtropical jet entrance/confluence over the western side of the continent that induces a secondary meridional circulation whose subsiding branch facilitates the equatorward displacement of the low-level anticyclone, particularly in the case of the less persistent events. In the case of the more persistent GFs the confluence is located farther east and sustains essentially zonal wave train propagation, so that the surface anticyclone is not able to achieve a major equatorward penetration. © 2007 American Meteorological Society. Fil:Müller, G.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Berri, G.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2007 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00270644_v135_n4_p1268_Muller http://hdl.handle.net/20.500.12110/paper_00270644_v135_n4_p1268_Muller
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Advection
Frost effects
Jets
Wind
Anticyclone
Atmospheric circulation
Generalized frosts
Rossby waves
Atmospheric movements
advection
anomaly
atmospheric circulation
cold air
frost
meridional circulation
Rossby wave
wave propagation
Argentina
South America
spellingShingle Advection
Frost effects
Jets
Wind
Anticyclone
Atmospheric circulation
Generalized frosts
Rossby waves
Atmospheric movements
advection
anomaly
atmospheric circulation
cold air
frost
meridional circulation
Rossby wave
wave propagation
Argentina
South America
Müller, Gabriela Viviana
Berri, Guillermo Jorge
Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
topic_facet Advection
Frost effects
Jets
Wind
Anticyclone
Atmospheric circulation
Generalized frosts
Rossby waves
Atmospheric movements
advection
anomaly
atmospheric circulation
cold air
frost
meridional circulation
Rossby wave
wave propagation
Argentina
South America
description This paper describes the large-scale atmospheric circulation associated with persistent generalized frosts (GFs; at least 75% of the stations report frosts) in the east-central region of Argentina known as the Wet Pampa. The GF events are grouped according to their persistence, and NCEP-NCAR reanalysis data are used to create daily composites of mass and wind field anomalies during the 1961-90 winters. The GFs are caused by an anticyclonic anomaly that enters South America, generating southerly wind anomalies and cold air advection that are strengthened by the meridional layout of a cyclonic anomaly over the South Atlantic Ocean. In the case of the more persistent events the wind anomaly grows during the previous days and becomes quasi-stationary. Also, the study identifies at 250 hPa a double train of eastward-moving Rossby waves along the subtropical and subpolar latitudes, respectively, of the Southern Hemisphere. The layout of both wave trains favors the development of an intense southerly wind anomaly in the entire southern cone of the continent. On the other hand, the propagation pattern during the less persistent GFs shows only one arc-shaped Rossby wave train that reaches South America, and then propagates northeastward. Additionally, there is a subtropical jet entrance/confluence over the western side of the continent that induces a secondary meridional circulation whose subsiding branch facilitates the equatorward displacement of the low-level anticyclone, particularly in the case of the less persistent events. In the case of the more persistent GFs the confluence is located farther east and sustains essentially zonal wave train propagation, so that the surface anticyclone is not able to achieve a major equatorward penetration. © 2007 American Meteorological Society.
author Müller, Gabriela Viviana
Berri, Guillermo Jorge
author_facet Müller, Gabriela Viviana
Berri, Guillermo Jorge
author_sort Müller, Gabriela Viviana
title Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
title_short Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
title_full Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
title_fullStr Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
title_full_unstemmed Atmospheric circulation associated with persistent generalized frosts in Central-Southern South America
title_sort atmospheric circulation associated with persistent generalized frosts in central-southern south america
publishDate 2007
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00270644_v135_n4_p1268_Muller
http://hdl.handle.net/20.500.12110/paper_00270644_v135_n4_p1268_Muller
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AT berriguillermojorge atmosphericcirculationassociatedwithpersistentgeneralizedfrostsincentralsouthernsouthamerica
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