Abstract
In this paper an application of clustering algorithms for statistical downscaling in short-range weather forecasts is presented. The advantages of this technique compared with standard nearest-neighbors analog methods are described both in terms of computational efficiency and forecast skill. Some validation results of daily precipitation and maximum wind speed operative downscaling (lead time 1–5 days) on a network of 100 stations in the Iberian Peninsula are reported for the period 1998–99. These results indicate that the weighting clustering method introduced in this paper clearly outperforms standard analog techniques for infrequent, or extreme, events (precipitation > 20 mm; wind > 80 km h−1). Outputs of an operative circulation model on different local-area or large-scale grids are considered to characterize the atmospheric circulation patterns, and the skill of both alternatives is compared.
Highlights
During the last two decades the skill of numerical atmospheric circulation models (ACMs) used for shortand medium-range weather prediction have increased substantially because of the advances both in assimilation procedures and physical parameterizations
This result indicates that the clustering process captures the periphery of the distribution of atmospheric patterns better than the fixed-size ensemble of nearest neighbors used in the standard analog method
We would like to mention that the results presented in this paper could be improved in the near future using the simulations of a new reanalysis project, European Centre for MediumRange Weather Forecasts (ECMWF) Re-Analysis-40 (ERA-40) covering the period from mid-1957 to 2001
Summary
During the last two decades the skill of numerical atmospheric circulation models (ACMs) used for shortand medium-range weather prediction have increased substantially because of the advances both in assimilation procedures and physical parameterizations. This method provides a local framework to train downscaling models using the information of the reanalysis database most similar to the low-resolution gridded forecast Some implementations of this method for detecting climatic anomalies (see Zorita and von Storch 1999; Wilby and Wigley 1997; and references therein) and for short-range forecast (see, e.g., Van den Dool 1989) have been presented in the literature. Both a limited-area and a large-scale grid are considered as different alternatives for characterizing atmospheric circulations patterns.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
