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Assessing two different climatic models and the NCEP-NCAR reanalysis data for the description of winter precipitation in the Iberian Peninsula

Journal: International Journal of Climatology
Year: 2004   Volume: 24
Initial page: 361   Last page: 376
Status: Published
PDF file: 2004_nieto_IJOC.pdf
DOI: 10.1002/joc.999
Nieto, S., , Rodríguez-Puebla, C.

The main questions motivating this study are: Can climate simulations describe the observations? To what extent can
we use climate models to predict climate change? For this purpose, an analysis was made of the correspondences and/or
discrepancies between observed winter precipitation data and the data from the National Centers for Environmental
Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis project, and from two global climatic
models: ECHAM4/OPYC3 and HadCM3. The data used correspond to the accumulated winter precipitation for the
period 1949–2000, and comparisons of the mean and variability patterns were made. The methods used were principal
components analysis, to break down variability and reduce the dimensions of the fields, and correlation and cross-spectrum
analyses for comparison of the time series. For all these, we studied the suitability of their average distributions, as well
as their modes of spatial and spectral variability. The results for the Iberian Peninsula show good agreement between
the precipitation data of the NCEP–NCAR reanalysis and the observations, both in the average analysis and in the main
modes of spatial and time variability. Therefore, the reanalysis data were proved to be a good resource for interpreting
climate variations. As regards the climatic models considered, in general the results point to their suitability for describing
the spatial distribution of winter precipitation, whereas the spectral association is less appropriate. The variability of the
precipitation data was related to circulation patterns and teleconnection indices, such as the North Atlantic oscillation and
the Arctic oscillation. The results allow us to conclude that the discrepancies between the two models and observations
must be due to a weak representation of the interannual variability.