Abstract
Maximum (Tmax), minimum (Tmin), mean (Tmean) air temperature and diurnal temperature range (DTR) trends on a seasonal and annual time scale are evaluated from data recorded at nine Spanish weather stations during the period 1950–2011. Temporal and spatial variability in temperatures and in the diurnal temperature range (DTR) are presented. The non-parametric Theil-Sen approach and the Mann-Kendall test are used to evaluate anomaly temperature trends and their statistical significance, respectively. An air temperature reduction in Spain between 1950 and 1980 emerges and significant warming is observed between 1980 and 2011. On a seasonal scale, the weakest trends (mostly insignificant at the 5% confidence level) are noted during autumn, while the strongest warming rates were found during summer and spring. The rate of change between 1950 and 2011 in Tmax, Tmin and Tmean was 1.6 °C, 1.1 °C and 1.3 °C, respectively. DTR trends showed a decrease on the Mediterranean coast and a small change in northern, Atlantic and rural areas. The spatial distribution of annual and seasonal trends was plotted as isoline maps and strong trend gradients from the south to the north of the country are observed. DTR values were negatively correlated with relative humidity and precipitation and positively correlated with sunshine hours.
Highlights
Various studies have confirmed global warming on regional, continental and global scales, [1].According to the Fifth Assessment Report (AR5) of the Intergovernmental Panel for Climate Change (IPCC), global mean surface temperature (GMST) has increased since the late 19th century, [1]
Trends in three different areas and at four rural stations, Santiago de Compostela, Zaragoza, Granada and Villalba, Acero et al [44] and it observed that seasonal diurnal temperature range (DTR) trend values were relatively small, almost all positive and they ranged between 0.23 and −0.08 ◦ C decade−1
It has been observed that Tmax, Tmin and Tmean trends increased and DTR trends decrease at certain stations in Spain
Summary
Various studies have confirmed global warming on regional, continental and global scales, [1]. According to the Fifth Assessment Report (AR5) of the Intergovernmental Panel for Climate Change (IPCC), global mean surface temperature (GMST) has increased since the late 19th century, [1]. When multiple independently produced datasets exist, the warming trend was 0.89 (0.69 to 1.08) ◦ C over the period. The trend and warming were 0.72 (0.49 to 0.89) ◦ C over the period 1951–2012 when based on three independently produced datasets. Evaluating temperature trends on a global scale is essential studying temperature variability on local and regional scales proves to be more inclusive, since changes on temperature are not uniform and vary over space and time
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