The Northwestern Argentinean Low: A Study of Two Typical Events

Autores
Seluchi, Marcelo Enrique; Saulo, Andrea Celeste; Nicolini, Matilde; Satyamurty, Prakki
Año de publicación
2003
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
A low pressure system [known as the northwestern Argentinean low (NAL)] is commonly observed over northwestern Argentina near the Andean slopes. This study describes two NAL episodes for summer and winter, with emphasis on the characterization of their three-dimensional structure and temporal variability. With the aid of a high-resolution regional model [Eta/Centro de Previsa˜o de Tempo e Estudos Clima´ticos (CPTEC)], the main mechanisms involved in the NAL life cycle were studied in order to examine how the thermal topographical processes influenced the system behavior. Surface pressure changes in the NAL are mostly dominated by the 600–900-hPa thickness variability, suggesting its thermal character. Based on this result, the temperature tendency equation has been used to quantify all the contributions to thermal changes. The summer NAL has a significant diurnal cycle that has been dominated by surface warming. This single mechanism can explain the low pressure system formation by itself, suggesting that the NAL could always be present during this season unless an adverse process counteracts the positive contribution by the surface sensible heat flux. Other favoring processes found in the analyzed cases were the Foehn effect (warming by subsidence) and the latent heat release. The intermittent behavior of the NAL is associated with a suppression of net warming in the 600–900-hPa layer, due to a cold-air outbreak. In the winter case, the Foehn effect has been mainly responsible for the NAL development. This mechanism acts in connection with an upper-level cyclonic disturbance approaching the Andes, indicating that the thermal response is triggered by a dynamical forcing. As the Foehn effect (locally known as Zonda wind) is a frequent winter phenomenon, the NAL intermittence during this season could be related to transient baroclinic activity, which modulates both the intensification and the decay stages. The NAL has been regarded as a thermal-orographic system. This study suggests that the analyzed NALs behave as an almost ‘‘pure’’ surface thermally driven low in summer, while dynamical-orographic forcing is the organizing mechanism in winter.
Fil: Seluchi, Marcelo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
Fil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina
Fil: Nicolini, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina
Fil: Satyamurty, Prakki. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
Materia
ARGENTINA
NORTHWESTERN
NAL
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/182458

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network_name_str CONICET Digital (CONICET)
spelling The Northwestern Argentinean Low: A Study of Two Typical EventsSeluchi, Marcelo EnriqueSaulo, Andrea CelesteNicolini, MatildeSatyamurty, PrakkiARGENTINANORTHWESTERNNALhttps://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1A low pressure system [known as the northwestern Argentinean low (NAL)] is commonly observed over northwestern Argentina near the Andean slopes. This study describes two NAL episodes for summer and winter, with emphasis on the characterization of their three-dimensional structure and temporal variability. With the aid of a high-resolution regional model [Eta/Centro de Previsa˜o de Tempo e Estudos Clima´ticos (CPTEC)], the main mechanisms involved in the NAL life cycle were studied in order to examine how the thermal topographical processes influenced the system behavior. Surface pressure changes in the NAL are mostly dominated by the 600–900-hPa thickness variability, suggesting its thermal character. Based on this result, the temperature tendency equation has been used to quantify all the contributions to thermal changes. The summer NAL has a significant diurnal cycle that has been dominated by surface warming. This single mechanism can explain the low pressure system formation by itself, suggesting that the NAL could always be present during this season unless an adverse process counteracts the positive contribution by the surface sensible heat flux. Other favoring processes found in the analyzed cases were the Foehn effect (warming by subsidence) and the latent heat release. The intermittent behavior of the NAL is associated with a suppression of net warming in the 600–900-hPa layer, due to a cold-air outbreak. In the winter case, the Foehn effect has been mainly responsible for the NAL development. This mechanism acts in connection with an upper-level cyclonic disturbance approaching the Andes, indicating that the thermal response is triggered by a dynamical forcing. As the Foehn effect (locally known as Zonda wind) is a frequent winter phenomenon, the NAL intermittence during this season could be related to transient baroclinic activity, which modulates both the intensification and the decay stages. The NAL has been regarded as a thermal-orographic system. This study suggests that the analyzed NALs behave as an almost ‘‘pure’’ surface thermally driven low in summer, while dynamical-orographic forcing is the organizing mechanism in winter.Fil: Seluchi, Marcelo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Nicolini, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Satyamurty, Prakki. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; BrasilAmer Meteorological Soc2003-10info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/182458Seluchi, Marcelo Enrique; Saulo, Andrea Celeste; Nicolini, Matilde; Satyamurty, Prakki; The Northwestern Argentinean Low: A Study of Two Typical Events; Amer Meteorological Soc; Monthly Weather Review; 131; 10; 10-2003; 2361-23780027-0644CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://journals.ametsoc.org/view/journals/mwre/131/10/1520-0493_2003_131_2361_tnalas_2.0.co_2.xmlinfo:eu-repo/semantics/altIdentifier/doi/10.1175/1520-0493(2003)131%3C2361:TNALAS%3E2.0.CO;2info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T09:46:04Zoai:ri.conicet.gov.ar:11336/182458instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 09:46:04.604CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv The Northwestern Argentinean Low: A Study of Two Typical Events
title The Northwestern Argentinean Low: A Study of Two Typical Events
spellingShingle The Northwestern Argentinean Low: A Study of Two Typical Events
Seluchi, Marcelo Enrique
ARGENTINA
NORTHWESTERN
NAL
title_short The Northwestern Argentinean Low: A Study of Two Typical Events
title_full The Northwestern Argentinean Low: A Study of Two Typical Events
title_fullStr The Northwestern Argentinean Low: A Study of Two Typical Events
title_full_unstemmed The Northwestern Argentinean Low: A Study of Two Typical Events
title_sort The Northwestern Argentinean Low: A Study of Two Typical Events
dc.creator.none.fl_str_mv Seluchi, Marcelo Enrique
Saulo, Andrea Celeste
Nicolini, Matilde
Satyamurty, Prakki
author Seluchi, Marcelo Enrique
author_facet Seluchi, Marcelo Enrique
Saulo, Andrea Celeste
Nicolini, Matilde
Satyamurty, Prakki
author_role author
author2 Saulo, Andrea Celeste
Nicolini, Matilde
Satyamurty, Prakki
author2_role author
author
author
dc.subject.none.fl_str_mv ARGENTINA
NORTHWESTERN
NAL
topic ARGENTINA
NORTHWESTERN
NAL
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv A low pressure system [known as the northwestern Argentinean low (NAL)] is commonly observed over northwestern Argentina near the Andean slopes. This study describes two NAL episodes for summer and winter, with emphasis on the characterization of their three-dimensional structure and temporal variability. With the aid of a high-resolution regional model [Eta/Centro de Previsa˜o de Tempo e Estudos Clima´ticos (CPTEC)], the main mechanisms involved in the NAL life cycle were studied in order to examine how the thermal topographical processes influenced the system behavior. Surface pressure changes in the NAL are mostly dominated by the 600–900-hPa thickness variability, suggesting its thermal character. Based on this result, the temperature tendency equation has been used to quantify all the contributions to thermal changes. The summer NAL has a significant diurnal cycle that has been dominated by surface warming. This single mechanism can explain the low pressure system formation by itself, suggesting that the NAL could always be present during this season unless an adverse process counteracts the positive contribution by the surface sensible heat flux. Other favoring processes found in the analyzed cases were the Foehn effect (warming by subsidence) and the latent heat release. The intermittent behavior of the NAL is associated with a suppression of net warming in the 600–900-hPa layer, due to a cold-air outbreak. In the winter case, the Foehn effect has been mainly responsible for the NAL development. This mechanism acts in connection with an upper-level cyclonic disturbance approaching the Andes, indicating that the thermal response is triggered by a dynamical forcing. As the Foehn effect (locally known as Zonda wind) is a frequent winter phenomenon, the NAL intermittence during this season could be related to transient baroclinic activity, which modulates both the intensification and the decay stages. The NAL has been regarded as a thermal-orographic system. This study suggests that the analyzed NALs behave as an almost ‘‘pure’’ surface thermally driven low in summer, while dynamical-orographic forcing is the organizing mechanism in winter.
Fil: Seluchi, Marcelo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
Fil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina
Fil: Nicolini, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina
Fil: Satyamurty, Prakki. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
description A low pressure system [known as the northwestern Argentinean low (NAL)] is commonly observed over northwestern Argentina near the Andean slopes. This study describes two NAL episodes for summer and winter, with emphasis on the characterization of their three-dimensional structure and temporal variability. With the aid of a high-resolution regional model [Eta/Centro de Previsa˜o de Tempo e Estudos Clima´ticos (CPTEC)], the main mechanisms involved in the NAL life cycle were studied in order to examine how the thermal topographical processes influenced the system behavior. Surface pressure changes in the NAL are mostly dominated by the 600–900-hPa thickness variability, suggesting its thermal character. Based on this result, the temperature tendency equation has been used to quantify all the contributions to thermal changes. The summer NAL has a significant diurnal cycle that has been dominated by surface warming. This single mechanism can explain the low pressure system formation by itself, suggesting that the NAL could always be present during this season unless an adverse process counteracts the positive contribution by the surface sensible heat flux. Other favoring processes found in the analyzed cases were the Foehn effect (warming by subsidence) and the latent heat release. The intermittent behavior of the NAL is associated with a suppression of net warming in the 600–900-hPa layer, due to a cold-air outbreak. In the winter case, the Foehn effect has been mainly responsible for the NAL development. This mechanism acts in connection with an upper-level cyclonic disturbance approaching the Andes, indicating that the thermal response is triggered by a dynamical forcing. As the Foehn effect (locally known as Zonda wind) is a frequent winter phenomenon, the NAL intermittence during this season could be related to transient baroclinic activity, which modulates both the intensification and the decay stages. The NAL has been regarded as a thermal-orographic system. This study suggests that the analyzed NALs behave as an almost ‘‘pure’’ surface thermally driven low in summer, while dynamical-orographic forcing is the organizing mechanism in winter.
publishDate 2003
dc.date.none.fl_str_mv 2003-10
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/182458
Seluchi, Marcelo Enrique; Saulo, Andrea Celeste; Nicolini, Matilde; Satyamurty, Prakki; The Northwestern Argentinean Low: A Study of Two Typical Events; Amer Meteorological Soc; Monthly Weather Review; 131; 10; 10-2003; 2361-2378
0027-0644
CONICET Digital
CONICET
url http://hdl.handle.net/11336/182458
identifier_str_mv Seluchi, Marcelo Enrique; Saulo, Andrea Celeste; Nicolini, Matilde; Satyamurty, Prakki; The Northwestern Argentinean Low: A Study of Two Typical Events; Amer Meteorological Soc; Monthly Weather Review; 131; 10; 10-2003; 2361-2378
0027-0644
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://journals.ametsoc.org/view/journals/mwre/131/10/1520-0493_2003_131_2361_tnalas_2.0.co_2.xml
info:eu-repo/semantics/altIdentifier/doi/10.1175/1520-0493(2003)131%3C2361:TNALAS%3E2.0.CO;2
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv Amer Meteorological Soc
publisher.none.fl_str_mv Amer Meteorological Soc
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 13.070432