SURFACE OZONE CONCENTRATIONS AND ITS RELATION TO WIND FIELD IN ISTANBUL SEMA TOPCU 1∗ , UMIT ANTEPLIOGLU 2 and SELAHATTIN INCECIK 1 1 Department of Meteorology, Istanbul Technical University, Istanbul, Turkey; 2 Kandilli Observatory, Bosphorus University, Cengelkoy, Istanbul ( ∗ author for correspondence, e-mail: stopcu@itu.edu.tr, Fax: +90 212 2853139) (Received November 2002; accepted 5 February 2003) Abstract. In this study, an assessment has been made on the wind speed; temperature and atmo- spheric pressure were analyzed by considering meteorological variables for selected high ozone cases. The Systems Applications International Meso-scale Model (SAIMM), a prognostic meteor- ological model was used to develop the 3-dimensional meteorological inputs to a chemical model. Meteorological conditions favorable for high ozone concentrations appear when Istanbul and the surrounding region is dominated by an anticyclonic pressure system. During the ozone favorable days, south and southwesterly winds with low wind speed influence Istanbul. We presented wind field simulations for a case study in explaining the ozone formation mechanism over Istanbul. Keywords: air pollution in Istanbul, local and meso-scale conditions, surface ozone 1. Introduction Meteorology is well known to be an important factor contributing to air quality. Hence, meteorological fields are required inputs for air-quality models. It encom- passes many atmospheric processes that control or strongly influence the evolu- tion of chemical species (Seamon, 2000). Surface ozone, the most well known substance within photochemical smog, plays an important role in affecting the re- gional climate and causing harmful effects on health. Because, the number of motor vehicles world-wide is growing by about 5% per year, far faster than the global human population, which has been increasing by about 2% per year (Schwela and Zali, 1999). In the last two decades air quality and meteorological field measure- ment programs supporting meteorological and photochemical modeling and data analysis have been made throughout the world (Solomon, 1995). The goals of these programs are to develop the meteorological inputs to chemical models and to provide improved understanding of the chemical and physical processes. The programs will also allow effective emissions management strategies for attaining and maintaining ambient air quality standards for ozone (Pearson and Fitzgerald, 2001). Although Istanbul has not yet experienced critical levels, ozone potential prob- lem is growing with the rapid development of transportation in the city. The number of the motor vehicles has increased as a result of economic growth. Otherwise, the Water, Air, and Soil Pollution: Focus 3: 53–64, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.