Evaporation trends in Spain: A comparison of class A pan and Piché atmometer measurements

Open Access

Abstract

Interest is growing in the trends of atmospheric evaporation demand, increasing the need for long-term time series. This work describes, for the first time, the development of a dataset on evaporation in Spain based on long-term series of Piché and pan measurement records. Piché measurements have been reported for >50 stations since the 1960s. Measurements of pan evaporation, which is a much more widely studied variable in the literature, are also available, but only since 1984 for 21 stations. Particular emphasis was placed on the homogenization of this dataset. Both the mean annual Piché and pan series over Spain showed evaporative increases during the common study period (1985?2011), by a rate of around +0.1 mm d?1 decade?1. Furthermore, using the annual Piché records since the 1960s, an evaporation decline was detected from the 1960s to the mid-1980s, which resulted in a non-significant trend over the entire 1961?2011 period. Our results indicate agreement between the decadal variability of reference evapotranspiration and the surface solar radiation previously reported and the evaporation from Piché and pan measurements, especially during summer. The suitability of Piché records compared to pan evaporation data to represent past trends is discussed. © 2014 Inter-Research. ; This work has been supported by the research projects CGL2010-17172/BOS, CGL2011-27574- CO2- 02, CGL2011-27536, CGL2010-18456 and Consolider- Ingenio Montes CSD2008-00040 financed by the Spanish Commission of Science and Technology and FEDER; 'Demonstration and validation of innovative methodology for regional climate change adaptation in the Mediterranean area (LIFE MEDACC)' financed by the LIFE programme of the European Commission; and SGR 2009-458 financed by the Catalan Government. A.S.L. was supported by the 'Secretaria per a Universitats i Recerca del Departament d'Economia i Coneixement, de la Generalitat de Catalunya i del programa Cofund de les Accions Marie Curie del 7è Programa marc d'R+D de la Unió Europea' (2011 BP-B 00078) and the postdoctoral fellowship No. JCI- 2012-12508. C.A.M. was given a grant by the 'Juan de la Cierva' programme (JCI-2011-10263) of the MICINN. We thank AEMET for providing the evaporation data. ; Peer Reviewed