Remote sensing measurements of aerosol optical thickness and correlation with in-situ air quality parameters during a haze episode in Thailand

Abstract

Thailand has experienced one of its worst hazes in 2007 due to intensive forest fires and slash-and-burn farming. The air quality monitoring stations and meteorological stations in Thailand provide valuable, concurrent information on the air quality during any period of the year and properties such as the concentrations of sulphur dioxide, nitrogen oxide, carbon monoxide, ozone and particulate mass (PM 10) have been routinely measured during the haze event. However, the limited coverage of these monitoring stations greatly constrains our ability to study and monitor the spatial and temporal variability of the haze in areas lacking monitoring stations. As such, in this paper, we combine the standard in-situ measurements of PM 10 with remote sensing imagery obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites. Firstly, the columnar aerosol optical thickness (AOT) is derived from the MODIS imagery for regions where PM 10 measurements are available. Secondly, a correlation between AOT and PM 10 measurements is established, taking into consideration the inherent experimental errors that occur during in-situ measurements and the accuracy of MODIS AOT retrieval product. With this combined approach, we expect to enhance and complement the current capabilities on the monitoring of air quality and extend it to areas not yet covered by monitoring stations during the haze period.