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Abstract:

This paper concentrates on the analysis of the life cycle of the low-level jet (LLJ) during a summer Chaco jet event. This is accomplished through the use of the Eta/Centro de Previsão del Tempo e Estudos Climáticos (CPTEC) regional model, in order to obtain high temporal and spatial detail of the main processes taking place. Both the low-level circulation and the geopotential height evolution at different latitudes are analyzed to provide a more detailed description of the effects of topography and differential warming on the evolution of this current. This study shows that the life cycle of the particular event analyzed is not the same at the different latitudes swept by this well-organized northerly current, expanding from 15° to 32°S during two consecutive days. A common feature to all the examined latitudes is the presence of a diurnal cycle linked to local effects, which is more evident during the first day and a half of the simulation. This cycle was identified not only by a nocturnal maximum of the wind, but also by the oscillations of the geostrophic wind close to the surface in response to differential warming over sloping terrain. However, during the second day, the diurnal oscillation is superseded by synoptic-scale forcing. The meridional growth of this northerly current reacts basically to a deepening of the northwestern Argentinean low, consequently becoming a geostrophic response to a synoptic perturbance. However, during the final stages of this event, a northerly wind area located over the southern tip of the current, which notably increases the northerlies' penetration toward higher latitudes, develops. This last extension is mainly due to a component of ageostrophic origin. Evidence is provided in support of the hypothesis that this secondary development is a feedback between the LLJ and the precipitation at the exit region. © 2004 American Meteorological Society.

Registro:

Documento: Artículo
Título:A case study of a chaco low-level jet event
Autor:Saulo, A.C.; Seluchi, M.E.; Nicolini, M.
Filiación:Ctro. Invest. del Mar/la Atmosfera, Depto. de Cie. Atmosfera/los Oceanos, University of Buenos Aires, 2do piso, pabellon II, 1428 Ciudad de Buenos Aires, Argentina
Ctro. Previsao Tempo Estudos Climati, Cacheoira Paulista, Sã Paulo, Brazil
Palabras clave:Computer simulation; Mathematical models; Oscillations; Precipitation (chemical); Wind; Geostrophic wind; Low-level jets (LLJ); Synoptic perturbance; Jets; jet; life cycle; modeling; spatiotemporal analysis; summer
Año:2004
Volumen:132
Número:11
Página de inicio:2669
Página de fin:2683
DOI: http://dx.doi.org/10.1175/MWR2815.1
Título revista:Monthly Weather Review
Título revista abreviado:Mon. Weather Rev.
ISSN:00270644
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00270644_v132_n11_p2669_Saulo

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Citas:

---------- APA ----------
Saulo, A.C., Seluchi, M.E. & Nicolini, M. (2004) . A case study of a chaco low-level jet event. Monthly Weather Review, 132(11), 2669-2683.
http://dx.doi.org/10.1175/MWR2815.1
---------- CHICAGO ----------
Saulo, A.C., Seluchi, M.E., Nicolini, M. "A case study of a chaco low-level jet event" . Monthly Weather Review 132, no. 11 (2004) : 2669-2683.
http://dx.doi.org/10.1175/MWR2815.1
---------- MLA ----------
Saulo, A.C., Seluchi, M.E., Nicolini, M. "A case study of a chaco low-level jet event" . Monthly Weather Review, vol. 132, no. 11, 2004, pp. 2669-2683.
http://dx.doi.org/10.1175/MWR2815.1
---------- VANCOUVER ----------
Saulo, A.C., Seluchi, M.E., Nicolini, M. A case study of a chaco low-level jet event. Mon. Weather Rev. 2004;132(11):2669-2683.
http://dx.doi.org/10.1175/MWR2815.1