Assessing potential evapotranspiration methods in future drought projections across Canada

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DOI

https://doi.org/10.1080/07055900.2023.2288632

Langue de publication
Anglais
Date
2023-12-11
Type
Article
Auteur(s)
  • Tam, Benita
  • Bonsal, Barrie
  • Zhang, Xuebin
  • Zhang, Qinxiao
  • Rong, Robin
Éditeur
Taylor & Francis

Résumé

Recently, concerns have arisen as to whether temperature-based proxy methods used to estimate potential evapotranspiration (PET) are reliable when examining future drought severity, especially in the context of a warmer climate. The objective of this study was to assess the effect of different PET approaches, focusing on proxies for radiation and humidity, on future Standardized Precipitation Evapotranspiration Index (SPEI) calculations across Canada. Using output from 22 CMIP6 global climate models (GCMs), seasonal and annual SPEI comparisons were carried out between the physically-based Penman-Monteith (PM) method and two approaches that incorporate temperature proxies to calculate radiation and/or humidity. These included the temperature-based Hargreaves (HG) approach and a PM method with derived humidity (PM-m). Results revealed that although the general patterns of SPEI projections across Canada were consistent among the methods, notable spatial and temporal differences were apparent. Specifically, both median and extreme SPEI projections based on the two temperature proxy methods revealed less annual and summer drying in much of central, eastern, and northern regions of Canada when compared to the physically based SPEI-PM. In extreme western regions (British Columbia, Yukon) these two methods, particularly HG, projected drier conditions. Differences of using temperature derived radiation and humidity were also most apparent in spring (and to a lesser degree, autumn), where the HG approach overestimated spring drying (and autumn wetting) over large regions of the country. Overall, differences tended to be more pronounced for the fully temperature-based HG approach during all periods considered. Results from this study strongly suggest that when possible, a physically-based approach be used when estimating PET to assess future drought projections. If a temperature proxy is used, the differences to a physically-based method should be understood and resultant implications be evaluated.

Résumé en langage clair

The objective of this paper was to assess the effect of different potential evapotranspiration (PET) approaches, focusing on proxies for radiation and humidity, on future Standardized Precipitation Evapotranspiration Index (SPEI) calculations across Canada. Using output from 22 global climate models, seasonal and annual SPEI comparisons were carried out between the physically based Penman-Monteith method and two approaches that incorporate temperature proxies to calculate radiation and/or humidity.

Cet article porte sur des travaux qui visent à évaluer l’effet de différentes approches d’évapotranspiration potentielle (ETP), en mettant l’accent sur des variables substitutives pour le rayonnement et l’humidité, dans les futurs calculs de l’indice normalisé d’évapotranspiration des précipitations (SPEI) à l’échelle du Canada. Compte tenu de résultats provenant de 22 modèles climatiques mondiaux, des comparaisons saisonnières et annuelles de l’indice SPEI ont été effectuées entre la méthode physique de Penman-Monteith et deux approches intégrant des variables substitutives de température pour calculer le rayonnement et/ou l’humidité.

Sujet

  • Sciences et technologie,
  • Climat

Droits

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Pagination

193-205

Évalué par les pairs

Yes

Niveau de libre accès

Or

Identifiants

ISSN
0705-5900
1480-9214

Article

Titre de la revue
Atmosphere-Ocean
Volume de la revue
62
Numéro de revue
3
Date d'acceptation
2023-11-10
Date de soumission
2023-06-23

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Collection(s)

Climate and weather

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