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

Abstract

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 ET o , 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 ET o . More than 90 % of the observed ET o 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 ET o , relative humidity was the main driver of the observed ET o trends. The observed trend could have negative consequences in a number of water-depending sectors if it continues in the future.

Recent changes of relative humidity: regional connections with land and ocean processes

“…Also, based on a newly developed homogeneous gridded database that employed the most available stations from the telecommunication system of the WMO, Willett et al (2014) found significant negative changes in RH, with strong spatial variability, at the global scale. This global pattern was also confirmed at the regional scale, but with different signs of change, including both negative (e.g., Vincent et al, 2007;Vicente-Serrano et al, 2014bZongxing et al, 2014) and positive trends (e.g., Shenbin et al, 2006;Jhajharia et al, 2009;Hosseinzadeh Talaee et al, 2012).…”

Assessing estimates of evaporative demand in climate models using observed pan evaporation over China

“…Second, the “observed” radiative and aerodynamic components were calculated from meteorological data based on a modified Penman equation (PenPan model) due to no direct measurements available, which may inherit some uncertainty as well. For example, the radiative component of pan evaporation was estimated from the sunshine duration, which is strongly influenced by the cloud coverage and aerosol [ Stanhill and Cohen , ; Zhou and Du , ; Wild , ]; based on that, the sunshine duration has showed adequate capacity to construct long‐term radiation and was widely applied in many countries and regions [ Wang et al ., ; Azorin‐Molina et al ., ; Vicente‐Serrano et al ., ]. Moreover, several other improvement need also to be made in the PenPan model, especially in the calculation of the pan albedo and more accurate treatment of pan's incoming and outgoing long‐wave radiations [ Rotstayn et al ., ; Roderick et al ., ; Li et al ., ].…”

Unraveling the influence of atmospheric evaporative demand on drought and its response to climate change

“…Focusing on physical models calculated from meteorological data, there have been numerous recent regional studies analyzing AED trends using Penman's equation (Penman, ). These studies show both positive (Gocic & Trajkovic, ; Piticar et al, ; Vicente‐Serrano, Azorin‐Molina, Sanchez‐Lorenzo, Revuelto, López‐Moreno, et al, ; Vicente‐Serrano, Azorin‐Molina, Sanchez‐Lorenzo, Revuelto, Morán‐Tejeda, et al, ; Vicente‐Serrano, Lopez‐Moreno, et al, ; Vicente‐Serrano et al, ) and negative (Jhajharia et al, ; H. Wang et al, ; Q. Wang et al, ; Z. Wang et al, ) trends in different regions. Over the globe K. Wang et al () used more than 4,200 stations were used to estimate AED trends between 1982 and 2008.…”