Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective
The mechanisms underlying the occurrence of temperature extremes in Iberia are analysed considering a Lagrangian perspective of the atmospheric flow, using 6-hourly ERA-Interim reanalysis data for the years 1979–2012. Daily 2-m minimum temperatures below the 1st percentile and 2-m maximum temperatur...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/101056 2023-05-15T17:35:38+02:00 Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective Santos, João A. Pfahl, Stephan Pinto, Joaquim G. Wernli, Heini 2015-04-22 application/application/pdf https://hdl.handle.net/20.500.11850/101056 https://doi.org/10.3929/ethz-b-000101056 en eng Taylor & Francis info:eu-repo/semantics/altIdentifier/doi/10.3402/tellusa.v67.26032 info:eu-repo/semantics/altIdentifier/wos/000353403500001 http://hdl.handle.net/20.500.11850/101056 doi:10.3929/ethz-b-000101056 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Tellus A: Dynamic Meteorology and Oceanography, 67 (1) Temperature extremes Cold episodes Warm episodes Lagrangian trajectories Large-scale circulation Surface fluxes Iberian Peninsula ERA-Interim info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2015 ftethz https://doi.org/20.500.11850/101056 https://doi.org/10.3929/ethz-b-000101056 https://doi.org/10.3402/tellusa.v67.26032 2022-04-25T13:57:57Z The mechanisms underlying the occurrence of temperature extremes in Iberia are analysed considering a Lagrangian perspective of the atmospheric flow, using 6-hourly ERA-Interim reanalysis data for the years 1979–2012. Daily 2-m minimum temperatures below the 1st percentile and 2-m maximum temperatures above the 99th percentile at each grid point over Iberia are selected separately for winter and summer. Four categories of extremes are analysed using 10-d backward trajectories initialized at the extreme temperature grid points close to the surface: winter cold (WCE) and warm extremes (WWE), and summer cold (SCE) and warm extremes (SWE). Air masses leading to temperature extremes are first transported from the North Atlantic towards Europe for all categories. While there is a clear relation to large-scale circulation patterns in winter, the Iberian thermal low is important in summer. Along the trajectories, air mass characteristics are significantly modified through adiabatic warming (air parcel descent), upper-air radiative cooling and near-surface warming (surface heat fluxes and radiation). High residence times over continental areas, such as over northern-central Europe for WCE and, to a lesser extent, over Iberia for SWE, significantly enhance these air mass modifications. Near-surface diabatic warming is particularly striking for SWE. WCE and SWE are responsible for the most extreme conditions in a given year. For WWE and SCE, strong temperature advection associated with important meridional air mass transports are the main driving mechanisms, accompanied by comparatively minor changes in the air mass properties. These results permit a better understanding of mechanisms leading to temperature extremes in Iberia. ISSN:0280-6495 ISSN:1600-0870 Article in Journal/Newspaper North Atlantic ETH Zürich Research Collection |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
Temperature extremes Cold episodes Warm episodes Lagrangian trajectories Large-scale circulation Surface fluxes Iberian Peninsula ERA-Interim |
spellingShingle |
Temperature extremes Cold episodes Warm episodes Lagrangian trajectories Large-scale circulation Surface fluxes Iberian Peninsula ERA-Interim Santos, João A. Pfahl, Stephan Pinto, Joaquim G. Wernli, Heini Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
topic_facet |
Temperature extremes Cold episodes Warm episodes Lagrangian trajectories Large-scale circulation Surface fluxes Iberian Peninsula ERA-Interim |
description |
The mechanisms underlying the occurrence of temperature extremes in Iberia are analysed considering a Lagrangian perspective of the atmospheric flow, using 6-hourly ERA-Interim reanalysis data for the years 1979–2012. Daily 2-m minimum temperatures below the 1st percentile and 2-m maximum temperatures above the 99th percentile at each grid point over Iberia are selected separately for winter and summer. Four categories of extremes are analysed using 10-d backward trajectories initialized at the extreme temperature grid points close to the surface: winter cold (WCE) and warm extremes (WWE), and summer cold (SCE) and warm extremes (SWE). Air masses leading to temperature extremes are first transported from the North Atlantic towards Europe for all categories. While there is a clear relation to large-scale circulation patterns in winter, the Iberian thermal low is important in summer. Along the trajectories, air mass characteristics are significantly modified through adiabatic warming (air parcel descent), upper-air radiative cooling and near-surface warming (surface heat fluxes and radiation). High residence times over continental areas, such as over northern-central Europe for WCE and, to a lesser extent, over Iberia for SWE, significantly enhance these air mass modifications. Near-surface diabatic warming is particularly striking for SWE. WCE and SWE are responsible for the most extreme conditions in a given year. For WWE and SCE, strong temperature advection associated with important meridional air mass transports are the main driving mechanisms, accompanied by comparatively minor changes in the air mass properties. These results permit a better understanding of mechanisms leading to temperature extremes in Iberia. ISSN:0280-6495 ISSN:1600-0870 |
format |
Article in Journal/Newspaper |
author |
Santos, João A. Pfahl, Stephan Pinto, Joaquim G. Wernli, Heini |
author_facet |
Santos, João A. Pfahl, Stephan Pinto, Joaquim G. Wernli, Heini |
author_sort |
Santos, João A. |
title |
Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
title_short |
Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
title_full |
Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
title_fullStr |
Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
title_full_unstemmed |
Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective |
title_sort |
mechanisms underlying temperature extremes in iberia: a lagrangian perspective |
publisher |
Taylor & Francis |
publishDate |
2015 |
url |
https://hdl.handle.net/20.500.11850/101056 https://doi.org/10.3929/ethz-b-000101056 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Tellus A: Dynamic Meteorology and Oceanography, 67 (1) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.3402/tellusa.v67.26032 info:eu-repo/semantics/altIdentifier/wos/000353403500001 http://hdl.handle.net/20.500.11850/101056 doi:10.3929/ethz-b-000101056 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/101056 https://doi.org/10.3929/ethz-b-000101056 https://doi.org/10.3402/tellusa.v67.26032 |
_version_ |
1766134855309983744 |