engleski

Evaluation of the numerical forecast of the convective precipitation over Croatia

Recently, the dataset of days with convection was determined by means of lightning data. The selected dataset, that consists of 402 days in the warm part of the period of 2006-2009, showed characteristics of convective activity along the Adriatic coast and over the open sea. This selected dataset also offer possibility to evaluate numerical forecast of the convective precipitation. For this purpose, the WRF model was used in two versions, the uncoupled and coupled one. The latter comprises the WRF-OASIS-NEMO coupled system with a more realistic presentation of sea currents and SST. Both versions of the model provided forecasts for mean 3-h precipitation at 20 km horizontal resolution for the period 2006-2008. In order to evaluate the strong air-sea exchanges and their influence on the reliability of forecasts of convective precipitation, the performance of the forecast were studied with the means of a 2 × 2 contingency table and skill scores. Statistical analysis was done by calculating (among others) hit rates (HR), false-alarm rates (FAR) and false alarm ratios (FAR). The preliminary results showed that both versions of the model overestimated the real number of the convective events. Moreover, for the most convective area (North Adriatic) and the particular month (June 2008), the coupled system showed a better performance of forecasts than the uncoupled WRF model. Improvements were seen in more realistic: (i) duration of convective events, (ii) spatial distribution of the area covered by the convection, (iii) both average and maximum amounts of the convective precipitation.

convection; lightning; WRF; Adriatic

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