Iberia01: A new gridded dataset of daily precipitation and temperatures over Iberia

The present work presents a new observational gridded dataset (referred to as Iberia01) for daily precipitation and temperatures produced using a dense network (thousands) of stations over the Iberian Peninsula for the period 1971-2015 at 0.1° regular (and 0.11° CORDEX-compliant rotated) resolutions. We analyze mean and extreme indices and compare the results with the E-OBS v17 dataset (using both the standard and ensemble versions, at 0.25 and 0.1° resolutions, respectively), in order to assess observational uncertainty in this region. We show that Iberia01 produces more realistic precipitation patterns than E-OBS for the mean and extreme indices considered, although both are comparable for temperatures. To assess the differences between these datasets, a new probabilistic intercomparison analysis was performed, using the E-OBS ensemble (v17e) to characterize observational uncertainty and testing whether Iberia01 falls within the observational uncertainty range provided by E-OBS. In general, uncertainty values are large in the whole territory, with the exception of a number of kernels where the uncertainty is small, corresponding to the stations used to build the E-OBS grid. For precipitation, significant differences-at the 10% level-between both datasets were found for fewer than 25% of days over the Iberian Peninsula. For temperature, a very inhomogeneous spatial pattern was obtained, with either a small (in most of the regions) or large fraction of significantly different days, thus indicating sensible regions for observational uncertainty.
This research has been partially funded by the Spanish R&D program MINECO/FEDER (grant no. CGL2015-66583-R, project MULTI-SDM), the Portuguese Foundation for Science and Technology – FCT (grant no. PTDC/GEOMET/7078/2014, SOLAR project; grant no. UID/GEO/50019/2019, Instituto Dom Luiz).