Abstract:
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The complex topography and high climatic variability of the North Western
Mediterranean Basin (NWMB) require a detailed assessment of climate change projections at
high resolution. ECHAM5/MPIOM global climate projections for mid-21st century and three
different emission scenarios are downscaled at 10 km resolution over the NWMB, using the
WRF-ARW regional model. High resolution improves the spatial distribution of temperature
and precipitation climatologies, with Pearson's correlation against observation being higher for
WRF-ARW (0.98 for temperature and 0.81 for precipitation) when compared to the ERA40
reanalysis (0.69 and 0.53, respectively). However, downscaled results slightly underestimate
mean temperature (≈1.3 K) and overestimate the precipitation field (≈400 mm/year).
Temperature is expected to raise in the NWMB in all considered scenarios (up to 1.4 K for
the annualmean), and particularly during summertime and at high altitude areas. Annual mean
precipitation is likely to decrease (around −5 % to −13 % for the most extreme
scenarios). The climate signal for seasonal precipitation is not so clear, as it is highly
influenced by the driving GCM simulation. All scenarios suggest statistically significant
decreases of precipitation for mountain ranges in winter and autumn. High
resolution simulations of regional climate are potentially useful to decision makers.
Nevertheless, uncertainties related to seasonal precipitation projections still persist and have
to be addressed. |