资源环境科技发展态势分析平台

The aim of this study is to examine the ability of two modelling systems, a global and a regional, to reproduce the influence of Etesian winds on the ozone zonal distribution over Eastern Mediterranean. Specifically, the results of the global MACC (Monitoring Atmospheric Composition and Climate) reanalysis model (Integrated Forecast System - MOZART (IFS-MOZART)) and an ensemble of MACC regional air quality models (ENS) are compared versus observed data from three background monitoring stations in Central and Eastern Mediterranean (i.e. Gharb (ARB) - Malta, Finokalia (FIN) (Crete) - Greece and Agia Marina (CAO) - Cyprus). Two distinct group of days characterized by different wind flows are used for the evaluation assessment for a 5-month period (May to September) for two years (2011 - 2012). During the selected period, the Etesians are the predominant winds that blow from northern directions over the Aegean Sea, affecting ozone levels. The observed mean ozone concentrations at Eastern Mediterranean stations are about 5 ppbv higher during Etesian days than during non selected days whereas at the Central Mediterranean station (ARB), the difference between the two groups of days is small. Furthermore, the Eastern Mediterranean stations present generally higher observed ozone levels than the Central Mediterranean station with these differences intensifying during Etesian days. The evaluation results suggest that although the two modelling systems underestimate surface ozone concentrations systematically, they can capture to a certain extend the effect of the Etesian winds on the ozone zonal distribution. Specifically, FIN station which is directly under the influence of the Etesian winds presents higher simulated ozone values compared to the other two stations in agreement with the observations. For both modelling systems, the statistical evaluation metrics are better for the Central Mediterranean station, but there is a considerable improvement for the regional modelling system indicating that the ENS reproduces better the observed ozone values and zonal distribution in comparison to the IFS-MOZART.