engleski

Downscaling of ECMWF seasonal integrations by RegCM

The 50-km RegCM was used to dynamically downscale ECMWF operational and experimental seasonal integrations over the southern Europe/Mediterranean area. For operational seasonal forecasts, a major disadvantage was found to be a relative scarcity of ECMWF archived data available for downscaling: too few upper-air levels at 12-hour frequency. Also, downscaling of the whole ensemble (40 members) may not always be practical ; this implies designing an algorithm to select sub-ensembles. For experimental integrations (from the ENSEMBLES project), the input for downscaling was much better, but the size of ensembles (9 members) could be considered too small. When compared against gridded CRU data, an overall better representation of T2m and precipitation was obtained in RegCM. Although objective skill scores indicate no clear winner, RegCM tends to be better for higher thresholds (severe events) and over the mountains.

dynamical downscaling; seasonal prediction; RegCM

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