Dynamically based future daily and seasonal temperature scenarios analysis for the northern Iberian Peninsula

This research analyses the changes expected in the tails of the temperature distribution over the Basque Country area (Spain). The study is devoted to support the impact and adaptation studies to climate change coordinated in the framework of the multidisciplinary project K-EGOKITZEN. A set of regional climate model outputs from the EU-FP6 ENSEMBLES project at 25 x 25 km horizontal resolution is used to analyse daily maximum and minimum near-surface air temperature and relative humidity over land. Extreme events are assessed using climatic indices defined by the STARDEX methodology for summer and winter seasons for previous (19782000) and future projections (20012100). Current bias correction methods are discussed. In winter the tenth percentile of the minimum temperature shows a positive trend with an increase of 3 degrees C with a mean standard deviation of 0.6 degrees C. All the models show a 70% decrease of the number of frost days at the end of the century and cold-wave episodes tend to disappear from 2070 to 2100 in some of the models. In summer, the 90th percentile of daily temperature shows also a positive trend with an increase of upto 3.5 degrees C with a mean standard deviation of 1.2 degrees C. The duration of each heat episode increase by 30%: while in the reference period, on ensemble model average, the duration of each heat wave is 15 days; at the end of the century is 24 days. Copyright (c) 2011 Royal Meteorological Society