Aerosol Optical Depth: A study using Thailand based Brewer Spectrophotometers

•AODs measured in Bangkok exhibited higher values than Songkhla.•AODs were higher in the morning and evening in Bangkok.•AODs in Songkhla were slightly lower during the mornings and late afternoons.•AOD was seasonal in Bangkok, with the higher values found in summer.•There was no clear seasonal pattern of AOD in Songkhla.

The Aerosol Optical Depth (AOD) was retrieved from the direct-sun Brewer observation by the application of the Beer’s law for the years 1997–2011 at two monitoring sites in Thailand (Bangkok and Songkhla). AOD values measured in Bangkok exhibited higher values than Songkhla. In addition, AOD values were higher in the morning and evening in Bangkok. In contrast, the AOD values in Songkhla were slightly lower during the mornings and late afternoons. The variation of AOD was seasonal in Bangkok, with the higher values found in summer (from Mid-February to Mid-May) compared with rainy season (Mid-May to Mid-October), whilst there was no clear seasonal pattern of AOD in Songkhla.