Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection

The South American Low-Level Jet Experiment (SALLJEX) provided a unique dataset to investigate the existence of a mesoscale low-level circulation and of a diurnal cycle in its related convergence pattern over the Southeastern South American region east of the Andes, as well as its relationship with...

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Autores principales:	Nicolini, M., Skabar, Y.G.
Formato:	JOUR
Materias:	Andes mountain range Boundary layer convergence Initiation of deep convection Low-level jet Mesoscale mountain-plain wind regime Argentina Data sets Deep convection Diurnal cycle Diurnal oscillations Field campaign Flow regimes Frontal zones High resolution analysis Horizontal advection In-phase Low density Low level Low level jet Mean divergence Mesoscale Mesoscale circulation Mountain ranges Parana River Southern Brazil Subtropical latitudes Synoptic conditions Warm seasons Wind speed Zonal wind Boundary layers Natural convection Wind Landforms atmospheric circulation atmospheric convection atmospheric forcing atmospheric moisture data assimilation diurnal variation jet mesoscale motion nocturnal boundary layer wind zonal wind Andes
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_01698095_v100_n4_p377_Nicolini
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_01698095_v100_n4_p377_Nicolini
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spelling	todo:paper_01698095_v100_n4_p377_Nicolini2023-10-03T15:07:16Z Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection Nicolini, M. Skabar, Y.G. Andes mountain range Boundary layer convergence Initiation of deep convection Low-level jet Mesoscale mountain-plain wind regime Argentina Data sets Deep convection Diurnal cycle Diurnal oscillations Field campaign Flow regimes Frontal zones High resolution analysis Horizontal advection In-phase Initiation of deep convection Low density Low level Low level jet Mean divergence Mesoscale Mesoscale circulation Mountain ranges Parana River Southern Brazil Subtropical latitudes Synoptic conditions Warm seasons Wind speed Zonal wind Boundary layers Natural convection Wind Landforms atmospheric circulation atmospheric convection atmospheric forcing atmospheric moisture data assimilation diurnal variation jet mesoscale motion nocturnal boundary layer wind zonal wind Andes The South American Low-Level Jet Experiment (SALLJEX) provided a unique dataset to investigate the existence of a mesoscale low-level circulation and of a diurnal cycle in its related convergence pattern over the Southeastern South American region east of the Andes, as well as its relationship with deep convection during the warm season. The present paper builds upon high-resolution analyses produced, assimilating the data collected during the SALLJEX field campaign using BRAMS, and explores their capability to reproduce mesoscale circulations not resolved by the low density observational network available in this region. Results of the analyses show a diurnal oscillation signal in the mean boundary layer convergence pattern over the plains with a nocturnal (daytime) convergence (divergence) maximum. These results are coherent with previous findings of a nocturnal phase in the mature stage of organized deep convection and related precipitation in subtropical latitudes east of the Andes during the warm season. The diurnal cycle of convergence/divergence in the boundary layer is described over a 15-day period, during which different synoptic conditions occurred. During weakly forced environments a regime characterized by nocturnal eastward anomaly flow and convergence and daytime westward anomaly flow and divergence related to a mesoscale northwestern mountain-central plain flow regime dominates over the plains between the Andes Mountains, the Parana River Valley, and the southern Brazil mountain range. In contrast, during synoptic conditions dominated by the presence of a deep thermal low over northwestern Argentina and a related low-level jet, convergence at night is mainly accomplished by the predominantly meridional low-level jet, which exhibits an anomalous weak wind speed diurnal cycle with respect to its summer climatological mean. On the other hand daytime divergence is completely produced by the zonal wind component as in the previous synoptic situation. Mesoscale circulations are altered (still effecting mean divergence in the domain, which exhibits a diurnal oscillation) upon the initiation of deep convective circulations in the evening in an increasingly convectively unstable atmosphere driven by a persistent horizontal advection of heat and moisture at low levels and forced by convergence generated by the low-level jet and the presence of a frontal zone. Convection intensifies at night when its related convergence over the plains comes in phase with the convergence related to the nocturnal maximum in the low-level jet. © 2010 Elsevier B.V. Fil:Nicolini, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01698095_v100_n4_p377_Nicolini
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Andes mountain range Boundary layer convergence Initiation of deep convection Low-level jet Mesoscale mountain-plain wind regime Argentina Data sets Deep convection Diurnal cycle Diurnal oscillations Field campaign Flow regimes Frontal zones High resolution analysis Horizontal advection In-phase Initiation of deep convection Low density Low level Low level jet Mean divergence Mesoscale Mesoscale circulation Mountain ranges Parana River Southern Brazil Subtropical latitudes Synoptic conditions Warm seasons Wind speed Zonal wind Boundary layers Natural convection Wind Landforms atmospheric circulation atmospheric convection atmospheric forcing atmospheric moisture data assimilation diurnal variation jet mesoscale motion nocturnal boundary layer wind zonal wind Andes
spellingShingle	Andes mountain range Boundary layer convergence Initiation of deep convection Low-level jet Mesoscale mountain-plain wind regime Argentina Data sets Deep convection Diurnal cycle Diurnal oscillations Field campaign Flow regimes Frontal zones High resolution analysis Horizontal advection In-phase Initiation of deep convection Low density Low level Low level jet Mean divergence Mesoscale Mesoscale circulation Mountain ranges Parana River Southern Brazil Subtropical latitudes Synoptic conditions Warm seasons Wind speed Zonal wind Boundary layers Natural convection Wind Landforms atmospheric circulation atmospheric convection atmospheric forcing atmospheric moisture data assimilation diurnal variation jet mesoscale motion nocturnal boundary layer wind zonal wind Andes Nicolini, M. Skabar, Y.G. Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
topic_facet	Andes mountain range Boundary layer convergence Initiation of deep convection Low-level jet Mesoscale mountain-plain wind regime Argentina Data sets Deep convection Diurnal cycle Diurnal oscillations Field campaign Flow regimes Frontal zones High resolution analysis Horizontal advection In-phase Initiation of deep convection Low density Low level Low level jet Mean divergence Mesoscale Mesoscale circulation Mountain ranges Parana River Southern Brazil Subtropical latitudes Synoptic conditions Warm seasons Wind speed Zonal wind Boundary layers Natural convection Wind Landforms atmospheric circulation atmospheric convection atmospheric forcing atmospheric moisture data assimilation diurnal variation jet mesoscale motion nocturnal boundary layer wind zonal wind Andes
description	The South American Low-Level Jet Experiment (SALLJEX) provided a unique dataset to investigate the existence of a mesoscale low-level circulation and of a diurnal cycle in its related convergence pattern over the Southeastern South American region east of the Andes, as well as its relationship with deep convection during the warm season. The present paper builds upon high-resolution analyses produced, assimilating the data collected during the SALLJEX field campaign using BRAMS, and explores their capability to reproduce mesoscale circulations not resolved by the low density observational network available in this region. Results of the analyses show a diurnal oscillation signal in the mean boundary layer convergence pattern over the plains with a nocturnal (daytime) convergence (divergence) maximum. These results are coherent with previous findings of a nocturnal phase in the mature stage of organized deep convection and related precipitation in subtropical latitudes east of the Andes during the warm season. The diurnal cycle of convergence/divergence in the boundary layer is described over a 15-day period, during which different synoptic conditions occurred. During weakly forced environments a regime characterized by nocturnal eastward anomaly flow and convergence and daytime westward anomaly flow and divergence related to a mesoscale northwestern mountain-central plain flow regime dominates over the plains between the Andes Mountains, the Parana River Valley, and the southern Brazil mountain range. In contrast, during synoptic conditions dominated by the presence of a deep thermal low over northwestern Argentina and a related low-level jet, convergence at night is mainly accomplished by the predominantly meridional low-level jet, which exhibits an anomalous weak wind speed diurnal cycle with respect to its summer climatological mean. On the other hand daytime divergence is completely produced by the zonal wind component as in the previous synoptic situation. Mesoscale circulations are altered (still effecting mean divergence in the domain, which exhibits a diurnal oscillation) upon the initiation of deep convective circulations in the evening in an increasingly convectively unstable atmosphere driven by a persistent horizontal advection of heat and moisture at low levels and forced by convergence generated by the low-level jet and the presence of a frontal zone. Convection intensifies at night when its related convergence over the plains comes in phase with the convergence related to the nocturnal maximum in the low-level jet. © 2010 Elsevier B.V.
format	JOUR
author	Nicolini, M. Skabar, Y.G.
author_facet	Nicolini, M. Skabar, Y.G.
author_sort	Nicolini, M.
title	Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
title_short	Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
title_full	Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
title_fullStr	Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
title_full_unstemmed	Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection
title_sort	diurnal cycle in convergence patterns in the boundary layer east of the andes and convection
url	http://hdl.handle.net/20.500.12110/paper_01698095_v100_n4_p377_Nicolini
work_keys_str_mv	AT nicolinim diurnalcycleinconvergencepatternsintheboundarylayereastoftheandesandconvection AT skabaryg diurnalcycleinconvergencepatternsintheboundarylayereastoftheandesandconvection
_version_	1807321921762623488

Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection

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