The CCLM model control run outputs (1961–2000) were compared with measurement data at 17 meteorological stations. Three main discrepancies between the two data
sets were found. Firstly, the modelled total amount of precipitation exceeded the measured value by 10–20 percent. The smallest difference between the measured and modelled data was found in the highlands, which receive the largest amounts of precipitation. This means that, despite the high spatial model resolution, the impact of the relatively small highland selleck products area on the redistribution of the amount of precipitation is inaccurately represented. Other studies also show that the CCLM model outputs exceed measurement data in the whole of Europe (Roesch et al. 2008). Secondly, there are different numbers of days with precipitation. The output data of a control run gave 30% higher values for almost the whole country. The most significant inequality was obtained in summer. The model generated slight precipitation (0.1–0.5 mm) much more often. The possible reason for this is that the model calculates precipitation according to water content in the atmosphere, but precipitation does not always reach the ground. Furthermore, some precipitation can evaporate (especially in summer)
from the gauges. Besides, the model provides average data from a grid (400 km2); therefore, despite the spatial unevenness of precipitation, a small amount of precipitation is generated for the whole cell. Finally, extreme precipitation also differs. Heavy precipitation (> 15 mm per day) was measured more often compared with the modelled results. This is usually XL184 research buy a very local phenomenon and its spatial distribution field is very uneven. Meanwhile, the model showed only average values (less precipitation) for the grids. The measured and the modelled annual maximum mean values of precipitation were much more similar, however, the measured values being only STK38 up to 20% higher than the modelled ones. The biggest difference was located in the Žemaičiai Highlands (more frequent and intensive events).
For the above reasons, only relative changes, i.e. deviations from the control period (1971–2000) run, were used in this study. According to the CCLM model outputs, annual precipitation will increase in Lithuania in the 21st century. Simulations according to both scenarios predict a rise of 5–22% by the end of the century. The largest and statistically significant changes (above 15%) are anticipated for the Žemaičiai Highlands and coastal lowlands. The rate of change of all the precipitation indices will be uneven during the 21st century. A large increase was simulated for the first part of the century (a rise in precipitation of up to 10%). Minor changes are expected for the middle of the century; finally, positive changes are very likely to intensify in the last thirty years.