Cold season synoptic-scale waves over subtropical South America

The most active winter synoptic-scale wave patterns over South America are identified using an extended empirical orthogonal function (EEOF) technique and are physically diagnosed using composite methods. Results show that the leading modes of short timescale variability propagate along two main pat...

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Autores principales: Vera, C.S., Vigliarolo, P.K., Berbery, E.H.
Formato: JOUR
Materias:
Heat flux
Moisture
Perturbation techniques
Precipitation (meteorology)
Storms
Waves
Baroclinic growth
Weather forecasting
baroclinic wave
cyclone
jet flow
orography
synoptic meteorology
South America
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00270644_v130_n3_p684_Vera
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00270644_v130_n3_p684_Vera
record_format dspace
spelling todo:paper_00270644_v130_n3_p684_Vera2023-10-03T14:37:25Z Cold season synoptic-scale waves over subtropical South America Vera, C.S. Vigliarolo, P.K. Berbery, E.H. Heat flux Moisture Perturbation techniques Precipitation (meteorology) Storms Waves Baroclinic growth Weather forecasting baroclinic wave cyclone jet flow orography synoptic meteorology South America The most active winter synoptic-scale wave patterns over South America are identified using an extended empirical orthogonal function (EEOF) technique and are physically diagnosed using composite methods. Results show that the leading modes of short timescale variability propagate along two main paths: over the subtropical jet latitudes (~30°S) and over the subpolar jet latitudes (~60°S). This research focuses on the subtropical mode and its evolution over South America. The observed structure of the systems associated with the subtropical mode resembles that of midlatitude baroclinic waves. Both cyclonic and anticyclonic perturbations display significant modifications in their three-dimensional structure as they evolve over extratropical and subtropical South America. While the upper-level perturbations are mostly unaffected when moving eastward, the lower-level perturbations advance following the shape of the Andes Mountains and exhibit an abrupt equatorward migration at the lee side of the mountains. As a result of such detachment, smaller eddy heat fluxes are observed in the vicinity of the orography and consequently a weaker eddy baroclinic growth is observed. Once the upper-level system is on the lee side, the perturbations acquire a more typical baroclinic wave structure and low-level intensification of the system occurs. The latter is largest around 1000 km east of the orography, where enhanced moisture transports from tropical latitudes along the eastern portion of the low-level cyclone favor precipitation occurence over southeastern South America. Those precipitation processes seem to provide a diabatic source of energy that further contributes to the strengthening of the low-level cyclone. In addition, an intensification of the cyclone once over the ocean was found in 60% of the situations considered, which is consistent with previous research suggesting an additional source of moisture and heat flux due to the warm waters of the Brazil Current. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00270644_v130_n3_p684_Vera
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Heat flux
Moisture
Perturbation techniques
Precipitation (meteorology)
Storms
Waves
Baroclinic growth
Weather forecasting
baroclinic wave
cyclone
jet flow
orography
synoptic meteorology
South America
spellingShingle Heat flux
Moisture
Perturbation techniques
Precipitation (meteorology)
Storms
Waves
Baroclinic growth
Weather forecasting
baroclinic wave
cyclone
jet flow
orography
synoptic meteorology
South America
Vera, C.S.
Vigliarolo, P.K.
Berbery, E.H.
Cold season synoptic-scale waves over subtropical South America
topic_facet Heat flux
Moisture
Perturbation techniques
Precipitation (meteorology)
Storms
Waves
Baroclinic growth
Weather forecasting
baroclinic wave
cyclone
jet flow
orography
synoptic meteorology
South America
description The most active winter synoptic-scale wave patterns over South America are identified using an extended empirical orthogonal function (EEOF) technique and are physically diagnosed using composite methods. Results show that the leading modes of short timescale variability propagate along two main paths: over the subtropical jet latitudes (~30°S) and over the subpolar jet latitudes (~60°S). This research focuses on the subtropical mode and its evolution over South America. The observed structure of the systems associated with the subtropical mode resembles that of midlatitude baroclinic waves. Both cyclonic and anticyclonic perturbations display significant modifications in their three-dimensional structure as they evolve over extratropical and subtropical South America. While the upper-level perturbations are mostly unaffected when moving eastward, the lower-level perturbations advance following the shape of the Andes Mountains and exhibit an abrupt equatorward migration at the lee side of the mountains. As a result of such detachment, smaller eddy heat fluxes are observed in the vicinity of the orography and consequently a weaker eddy baroclinic growth is observed. Once the upper-level system is on the lee side, the perturbations acquire a more typical baroclinic wave structure and low-level intensification of the system occurs. The latter is largest around 1000 km east of the orography, where enhanced moisture transports from tropical latitudes along the eastern portion of the low-level cyclone favor precipitation occurence over southeastern South America. Those precipitation processes seem to provide a diabatic source of energy that further contributes to the strengthening of the low-level cyclone. In addition, an intensification of the cyclone once over the ocean was found in 60% of the situations considered, which is consistent with previous research suggesting an additional source of moisture and heat flux due to the warm waters of the Brazil Current.
format JOUR
author Vera, C.S.
Vigliarolo, P.K.
Berbery, E.H.
author_facet Vera, C.S.
Vigliarolo, P.K.
Berbery, E.H.
author_sort Vera, C.S.
title Cold season synoptic-scale waves over subtropical South America
title_short Cold season synoptic-scale waves over subtropical South America
title_full Cold season synoptic-scale waves over subtropical South America
title_fullStr Cold season synoptic-scale waves over subtropical South America
title_full_unstemmed Cold season synoptic-scale waves over subtropical South America
title_sort cold season synoptic-scale waves over subtropical south america
url http://hdl.handle.net/20.500.12110/paper_00270644_v130_n3_p684_Vera
work_keys_str_mv AT veracs coldseasonsynopticscalewavesoversubtropicalsouthamerica
AT vigliarolopk coldseasonsynopticscalewavesoversubtropicalsouthamerica
AT berberyeh coldseasonsynopticscalewavesoversubtropicalsouthamerica
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