INTERPOLATION CONSIDERATIONS WHEN COMPARING MODEL AND RAINGAUGE PRECIPITATION. HEAVY PRECIPITATION CASES ANALYSIS FOR SLOVENIA

The aim of this study was to form a method and find the highest model resolution for which the cell averaged interpolated fields of 24 h raingauge precipitation would be independent of the interpolation method. We used heavy precipitation data for Slovenia and three different interpolation methods. Cross-validation results showed that the magnitudes can be as large as 50 % of the measured maxima (in our case 50 mm - 110 mm). Therefore a reliable interpolation to high resolution and into a point is not sensible. We found that results became independent of the interpolation method when model cells arc apart at least two times of the average distance to the closest neighbor in the raingauge network. For our case this occurred at 16 km. At this resolution the absolute maximum difference was in most cases less than 15% of the measured maximum