Articles | Volume 20, issue 8
https://doi.org/10.5194/hess-20-3393-2016
https://doi.org/10.5194/hess-20-3393-2016
Research article
 | 
23 Aug 2016
Research article |  | 23 Aug 2016

Recent changes and drivers of the atmospheric evaporative demand in the Canary Islands

Sergio M. Vicente-Serrano, Cesar Azorin-Molina, Arturo Sanchez-Lorenzo, Ahmed El Kenawy, Natalia Martín-Hernández, Marina Peña-Gallardo, Santiago Beguería, and Miquel Tomas-Burguera

Abstract. We analysed recent evolution and meteorological drivers of the atmospheric evaporative demand (AED) in the Canary Islands for the period 1961–2013. We employed long and high-quality time series of meteorological variables to analyse current AED changes in this region and found that AED has increased during the investigated period. Overall, the annual ETo, which was estimated by means of the FAO-56 Penman–Monteith equation, increased significantly by 18.2 mm decade−1 on average, with a stronger trend in summer (6.7 mm decade−1). In this study we analysed the contribution of (i) the aerodynamic (related to the water vapour that a parcel of air can store) and (ii) radiative (related to the available energy to evaporate a quantity of water) components to the decadal variability and trends of ETo. More than 90 % of the observed ETo variability at the seasonal and annual scales can be associated with the variability in the aerodynamic component. The variable that recorded more significant changes in the Canary Islands was relative humidity, and among the different meteorological factors used to calculate ETo, relative humidity was the main driver of the observed ETo trends. The observed trend could have negative consequences in a number of water-depending sectors if it continues in the future.

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Short summary
In this work we analyse the recent evolution and meteorological drivers of the atmospheric evaporative demand in the Canary Islands. We found that the reference evapotranspiration increased by 18.2 mm decade−1 – on average – between 1961 and 2013, with the highest increase recorded during summer. This increase was mainly driven by changes in the aerodynamic component, caused by a statistically significant reduction of the relative humidity.