Episodic ozone air quality in Jakarta in relation to meteorological conditions

Surface O3 air quality in Jakarta, Indonesia, was analyzed using hourly monitoring data during January 2002–March 2004 from the five automatic monitoring stations with the aim to provide the first insight into the ozone formation and accumulation leading to the high ozone levels over the city. The city location near the equator with the intensive emission sources is of especial interest in this regard. The surface O3 levels in Jakarta were high which frequently exceeded the hourly national ambient air quality standard (120 ppb), i.e. over 450 hourly measurements in 2002 and 2003 or 0.7% over 66,000 hourly ozone measurements at the five stations during 2002–2003. The monthly average of O3 was maximum in October and minimum in February. Selected days of episodic high O3 in April, May, and October, and low ozone days in February were comparatively analyzed in relation to local and synoptic meteorological conditions. The high ozone days were characterized by more intense solar radiation, higher temperature, and lighter surface wind which are favorable for photochemical production of O3. Low pressure gradients on synoptic charts of the high ozone days linked to the low wind and more stagnant air that are favorable for ozone build-up over the city. Further studies, including photochemical modeling, are required to understand better the conditions leading to high ozone in the city in order to formulate the ozone management strategies.