Atmospheric evaporative demand observations, estimates and driving factors in Spain (1961-2011)
Vicente-Serrano, Sergio M.
McVicar, Tim R.
El Kenawy, Ahmed M.
KAUST DepartmentWater Desalination and Reuse Research Center (WDRC)
Environmental Science and Engineering Program
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AbstractWe analyzed the spatio-temporal evolution of evaporation observations from Piché atmometers (1961-2011; 56 stations) and Pan evaporimeters (1984-2011; 21 stations) across Spain, and compared both measurements with evaporation estimates obtained by four physical models: i.e., Food and Agricultural Organization-56 Penman-Monteith, Food and Agricultural Organization-Pan, PenPan and Penman, based on climate data. In this study we observed a positive and statistically significant correlation between Piché and Pan evaporation measurements during the common period (1984-2011; 19 stations), mainly in summer. When evaporation observations and estimates were compared, we detected positive and statistically significant correlations with the four methods, except for winter. Among the four physical models, the FAO-Pan showed the best fitting to both Piché and Pan evaporation measurements; the PenPan model overestimated evaporation rates; and the FAO-Penman-Monteith and Penman methods underestimated evaporation observations. We also observed a better spatial agreement between Pan evaporation and estimates than that obtained by Piché measurements. Annual and seasonal trends of evaporation estimates show a statistically significant increase for 1961-2011, which do not agree with long-term Piché evaporation trends; e.g. a discontinuity was found around the 1980s. Radiative and aerodynamic driving factors suggest that this discontinuity, and the observed evaporation trends across Spain could be associated with the abrupt increase in air temperature observed during last few decades (i.e., global warming). Further investigations using available Piché evaporation observations for other regions are needed to better understand physical components influencing long-term trends of evaporation.
SponsorsWe would like to thank the Spanish State Meteorological Agency (AEMET) for providing the climate database used in this study. C. A-M was supported by the JCI-2011-10263 Grant; and A. S-L received a postdoctoral fellowship from 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 7e Programa marc d'R+D de la Unio Europea" (2011 BP-B 00078) and by the JCI-2012-12508 Grant. This work was also supported by the research projects CGL2011-27574-CO2-02 financed by the Spanish Commission of Science and Technology and FEDER and "LIFE12 ENV/ES/000536-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. The authors wish to acknowledge the editor and the two anonymous reviewers for their detailed and helpful comments to the original manuscript.
JournalJournal of Hydrology