Daily Temperature Changes and Variability in ENSEMBLES Regional Models Predictions: Evaluation and Intercomparison for the Ebro Valley 2 (NE Iberia) 3 4 5

Thuwal Technology, Saudi Arabia
We employ a suite of regional climate models (RCMs) to assess future changes in summer 18 (JJA) maximum temperature (Tmax) over the Ebro basin, the largest hydrological division in 19 the Iberian Peninsula. Under the A1B emission scenario, future changes in both mean 20 values and their corresponding time varying percentiles were examined by comparing the 21 control period (1971-2000) with two future time slices: 2021-2050 and 2071-2100. Here, 22 the rationale is to assess how lower/upper tails
more » ... w lower/upper tails of temperature distributions will change in 23 the future and whether these changes will be consistent with those of the mean. The model 24 validation results demonstrate significant differences among the models in terms of their 25 capability to representing the statistical characteristics (e.g., mean, skewness and 26 asymmetry) of the observed climate. The results also indicate that the current substantial 27 warming observed in the Ebro basin is expected to continue during the 21st century, with 28 more intense warming occurring at higher altitudes and in areas with greater distance from 29 coastlines. All models suggest that the region will experience significant positive changes 30 in both the cold and warm tails of temperature distributions. However, the results 31 emphasize that future changes in the lower and upper tails of the summer Tmax distribution 32 may not follow the same warming rate as the mean condition. In particular, the projected 33 changes in the warm tail of the summer Tmax are shown to be significantly larger than 34 changes in both mean values and the cold tail, especially at the end of the 21st century. The 35 finding suggests that much of the changes in the summer Tmax percentiles will be driven by 36 a shift in the entire distribution of temperature rather than only changes in the central 37 tendency. Better understanding the possible implications of future climate systems provides 38 2 information useful for vulnerability assessments and the development of local adaptation 39 strategies for multidisciplinary investigations. 40 41