Cold surge episodes over southeastern Brazil - a potential vorticity perspective
Most intense cold surges and associated frost events in southern and southeastern Brazil are characterized by a large amplitude trough over South America extending toward tropical latitudes and a ridge to the west of it over the Pacific Ocean. In this study, potential vorticity (PV) streamers serve...
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ftdatacite:10.7892/boris.39674 2023-05-15T13:59:40+02:00 Cold surge episodes over southeastern Brazil - a potential vorticity perspective Arnold, Julian Sprenger, Michael Martius, Olivia 2013 application/pdf https://dx.doi.org/10.7892/boris.39674 http://boris.unibe.ch/39674/ en eng Wiley info:eu-repo/semantics/openAccess 550 Earth sciences & geology 910 Geography & travel Text article-journal ScholarlyArticle 2013 ftdatacite https://doi.org/10.7892/boris.39674 2021-11-05T12:55:41Z Most intense cold surges and associated frost events in southern and southeastern Brazil are characterized by a large amplitude trough over South America extending toward tropical latitudes and a ridge to the west of it over the Pacific Ocean. In this study, potential vorticity (PV) streamers serve to examine the flow condition leading to cold surges. Case studies suggest that several PV anomalies are related to cold surge episodes: (1) the potential vorticity unit (2-PVU) isoline upstream of South America becomes progressively more distorted prior and during the cold surge episode, indicating a flow situation which is conducive for Rossby wave breaking and hence a flow which strongly deviates from zonality; (2) the initial stage of a cold surge episode is characterized by a northward bulging of high-PV air to the east of the Andes, resulting in a PV streamer whose northern end reaches Uruguay and southeastern Brazil; the strong PV gradient on its western flank constitutes a flow configuration that induces and maintains the transport of sub-Antarctic air toward the subtropics; (3) a distinct negative PV anomaly, a blocking, originates over the eastern South Pacific, upstream of the South America sector. A composite analysis of 27 cold surges is performed for stratospheric PV streamer frequency on several isentropic surfaces. It reveals that equatorward wave breaking over South America and the western South Atlantic represents an important potential component of the dynamics of intense cold surges. The indications are most pronounced around the isentropic levels of 320 K and immediately before the day with largest temperature drops over subtropical Brazil. Text Antarc* Antarctic DataCite Metadata Store (German National Library of Science and Technology) Antarctic Pacific Uruguay |
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DataCite Metadata Store (German National Library of Science and Technology) |
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English |
topic |
550 Earth sciences & geology 910 Geography & travel |
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550 Earth sciences & geology 910 Geography & travel Arnold, Julian Sprenger, Michael Martius, Olivia Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
topic_facet |
550 Earth sciences & geology 910 Geography & travel |
description |
Most intense cold surges and associated frost events in southern and southeastern Brazil are characterized by a large amplitude trough over South America extending toward tropical latitudes and a ridge to the west of it over the Pacific Ocean. In this study, potential vorticity (PV) streamers serve to examine the flow condition leading to cold surges. Case studies suggest that several PV anomalies are related to cold surge episodes: (1) the potential vorticity unit (2-PVU) isoline upstream of South America becomes progressively more distorted prior and during the cold surge episode, indicating a flow situation which is conducive for Rossby wave breaking and hence a flow which strongly deviates from zonality; (2) the initial stage of a cold surge episode is characterized by a northward bulging of high-PV air to the east of the Andes, resulting in a PV streamer whose northern end reaches Uruguay and southeastern Brazil; the strong PV gradient on its western flank constitutes a flow configuration that induces and maintains the transport of sub-Antarctic air toward the subtropics; (3) a distinct negative PV anomaly, a blocking, originates over the eastern South Pacific, upstream of the South America sector. A composite analysis of 27 cold surges is performed for stratospheric PV streamer frequency on several isentropic surfaces. It reveals that equatorward wave breaking over South America and the western South Atlantic represents an important potential component of the dynamics of intense cold surges. The indications are most pronounced around the isentropic levels of 320 K and immediately before the day with largest temperature drops over subtropical Brazil. |
format |
Text |
author |
Arnold, Julian Sprenger, Michael Martius, Olivia |
author_facet |
Arnold, Julian Sprenger, Michael Martius, Olivia |
author_sort |
Arnold, Julian |
title |
Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
title_short |
Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
title_full |
Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
title_fullStr |
Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
title_full_unstemmed |
Cold surge episodes over southeastern Brazil - a potential vorticity perspective |
title_sort |
cold surge episodes over southeastern brazil - a potential vorticity perspective |
publisher |
Wiley |
publishDate |
2013 |
url |
https://dx.doi.org/10.7892/boris.39674 http://boris.unibe.ch/39674/ |
geographic |
Antarctic Pacific Uruguay |
geographic_facet |
Antarctic Pacific Uruguay |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.7892/boris.39674 |
_version_ |
1766268332876496896 |