Changes in occurrences of temperature extremes in continental Portugal: a stochastic approach
Abstract In this paper the tail regions of the air‐surface temperature are modelled explicitly, using the recent developments of extreme value theory. The tails are estimated by fitting a Generalized Pareto Distribution to the observations disregarding certain thresholds (lying beyond) that mark the...
| Published in: | Meteorological Applications |
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| Main Authors: | , , |
| Other Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2010
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/met.171 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fmet.171 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/met.171 |
| Summary: | Abstract In this paper the tail regions of the air‐surface temperature are modelled explicitly, using the recent developments of extreme value theory. The tails are estimated by fitting a Generalized Pareto Distribution to the observations disregarding certain thresholds (lying beyond) that mark the beginning of the tail regions. There are different approaches to characterize the spatial behaviour of climatological phenomena, and a particularly elegant formulation is derived from the theory of point process governing peaks‐over‐threshold. The aim of this study is to verify whether extreme values related to weather attributes from Continental Portugal (regional scale) show any structural alteration, which can reflect global changes during the last century. For this purpose, daily extremes of air‐surface temperatures, as well as the clustering of extreme temperatures defined by the peaks‐over‐random‐threshold (PORT) methodology, are strongly indicated to detect signals concerning global change. The analysis of meteorologically extreme events in Continental Portugal indicates that there has been a sizable change in their frequency. Even the experimental design, as presented here, does not allow an assessment of the reasons for these changes in frequency of temperature extremes, suggesting that natural variability in the climate system could be the cause of the recent changes, besides anthropogenic forcing due to the increase of greenhouse gas concentrations in the atmosphere. These findings can be linked to studies which have attempted to determine causing mechanisms, analysing large‐scale natural oscillations such as the North Atlantic Oscillation (NAO). Copyright © 2010 Royal Meteorological Society |
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