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Moratiel R.,Technical University of Madrid | Moratiel R.,Research Center for the Management of Agricultural and Environmental Risks | Duran J.M.,Technical University of Madrid | Duran J.M.,Research Center for the Management of Agricultural and Environmental Risks | Snyder R.L.,University of California at Davis
Climate Research | Year: 2010

We studied the sensitivity of reference evapotranspiration (ETo) to global warming in Spain at the end of the 21st century. The FAO-56 Penman-Monteith equation was used to estimate ETo, and we examined the sensitivity of the latter to changes in temperature and relative humidity. Changes in stomatal resistance in response to increased CO2 concentration were not evaluated, nor were the changes in wind velocity and solar radiation. Different scenarios were used for estimation of future ET o in different river basins as a consequence of trends in the maximum and minimum temperatures and maximum and minimum humidities during the period 1973-2002, as observed from 38 meteorological stations. The temperature increases ranged between 0.3 and 0.7°C decade-1, and the relative humidities fluctuated between 0.1 and -3.7% decade-1. Four scenarios were simulated that considered the variations in linear tendency of the maximum and minimum temperatures and maximum and minimum relative humidities. The trends of the 4 scenarios were incorporated with the data from 338 agrometeorological stations to estimate future ETo. In all cases, there was an annual increase in ETo of 11, 21, 36 and 7% above the annual ETo (1196 mm) for Scenarios 0, 1, 2 and 3, respectively. The river basin most affected by these changes was the Ebro River valley. The most affected months were May, June, July and August, while the least affected months were November, December and January. © Inter-Research 2010.


Moratiel R.,Technical University of Madrid | Moratiel R.,Research Center for the Management of Agricultural and Environmental Risks | Snyder R.L.,University of California at Davis | Duran J.M.,Technical University of Madrid | And 2 more authors.
Natural Hazards and Earth System Science | Year: 2011

The impact of climate change and its relation with evapotranspiration was evaluated in the Duero River Basin (Spain). The study shows possible future situations 50 yr from now from the reference evapotranspiration (ET o). The maximum temperature (Tmax), minimum temperature (Tmin), dew point (Td), wind speed (U) and net radiation (Rn) trends during the 1980-2009 period were obtained and extrapolated with the FAO-56 Penman-Montheith equation to estimate ET o. Changes in stomatal resistance in response to increases in CO 2 were also considered. Four scenarios were done, taking the concentration of CO2 and the period analyzed (annual or monthly) into consideration. The scenarios studied showed the changes in ETo as a consequence of the annual and monthly trends in the variables Tmax, Tmin, Td, U and Rn with current and future CO2 concentrations (372 ppm and 550 ppm). The future ETo showed increases between 118 mm (11 %) and 55 mm (5 %) with respect to the current situation of the river basin at 1042 mm. The months most affected by climate change are May, June, July, August and September, which also coincide with the maximum water needs of the basin's crops. © 2011 Author(s).


Moratiel R.,Technical University of Madrid | Moratiel R.,Research Center for the Management of Agricultural and Environmental Risks | Soriano B.,Research Center for the Management of Agricultural and Environmental Risks | Centeno A.,Technical University of Madrid | And 4 more authors.
Theoretical and Applied Climatology | Year: 2016

This study analyses trends of mean (Tm), maximum (Tx), minimum (Tn), dew point (Td), and wet-bulb temperatures (Tw) on an annual, seasonal, and monthly time scale over Spain during the period 1981–2010. The main purpose was to determine how temperature and humidity changes are impacting on Tw, which is probably a better measure of climate change than temperature alone. In this study, 43 weather stations were used to detect data trends using the nonparametric Mann-Kendall test and the Sen method to estimate the slope of trends. Significant linear trends observed for Tm, Tx, and Tn versus year were 56, 58, and 47 % of the weather stations, respectively, with temperature ranges between 0.2 and 0.4 °C per decade. The months with bigger trends were April, May, June, and July with the highest trend for Tx. The spatial behaviour of Td and Tw was variable, with various locations showing trends from −0.6 to +0.3 °C per decade for Td and from −0.4 to +0.5 °C per decade for Tw. Both Td and Tw showed negative trends for July, August, September, November, and December. Comparing the trends versus time of each variable versus each of the other variables exhibited poor relationships, which means you cannot predict the trend of one variable from the trend of another variable. The trend of Tx was not related to the trend of Tn. The trends of Tx, Tm, and Tn versus time were unrelated to the trends versus time of either Td or Tw. The trend of Tw showed a high coefficient of determination with the trend of Td with an annual value of R2 = 0.86. Therefore, the Tw trend is more related to changes in humidity than temperature. © 2016 Springer-Verlag Wien

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