Analysis of surface ozone in Istanbul by using cluster analysis and HYSPLIT model

Abstract

Istanbul is the largest and most populated city of Turkey and one of the biggest megacities in the world. In the framework of the TUBITAK-COST project 105Y005 and TUJJB-TUMEHAP project number 03-06, one urban (Göztepe which is nearby to major traffic), one sub-urban (Kandilli) an one rural (at the crest of Büyükada) stations have been established to investigate surface ozone concentration in Istanbul. The objectives of this study is to examine the temporal variations, the weekdayweekend and seasonal variations of surface ozone concentrations and their relation with the meteorological parameters as well as to investigation the transport mechanism of surface ozone by using the HYSPLIT model and cluster analysis between 2008 and 2009. Surface ozone profiles were monitored particulary in the ozone season from April 1 to October 1 that is characterized by high ozone levels According to the behaviour of ozone concentration on a diurnal basis, surface ozone trends generally showed maximum concentrations in afternoon hours and minimum concentrations at rush hours due to NOx titration by traffic emissions. Investigation of O3 trends during weekdays and weekends demonstrates that weekend ozone concentrations were confirmed to be greater than those of weekdays during early mornings hours especially in Göztepe. Analysis of seasonal variations of surface ozone shows that the maximum surface ozone concentration were observed during summer and while minimum concentrations occured during the colder months. Surface ozone levels had positive correlations with wind speed and temperature. Based on the results of the HYSPLIT model and cluster analysis that were used to understand the transport mechanism of surface ozone, the dominant wind direction was from northwest. Transport to Istanbul was mainly from the Balkans, Europe and Black Sea.