Intercomparison of two haze events observed using a ground-based backscatter lidar in Penang Island, Malaysia

A ground-based backscatter Lidar, operating at 355nm was setup at the roof top of School of Physics, Universiti Sains Malaysia to study the aerosol content around Penang Island. During the operation of the Lidar, it had successfully obtained information on two haze events that struck Penang Island, which occurred during the month of July 2013 and March 2014, respectively. It was found that these two haze events showed different characteristics, such as the numbers and thickness of the aerosol layers. Multiple layers of aerosol were found in haze event during March 2014 and the aerosol layers were very thick. In contrast, only a single layer of aerosol was found in the haze event during July 2013 and the aerosol layer was relatively thin. Columnar aerosol optical depth (AOD) of these two haze events also showed some differences. Columnar AOD for the haze event occurred in July 2013 varied between 1.00±0.11 to 1.82±0.01, while columnar AOD for haze event occurred during March 2014 varied between 0.47±0.15 to 3.03±0.05. Finally, by combining HYSPLIT backtrajectories and MODIS satellite data, the possible origin of the haze aerosol was determined. It was found that the haze aerosol is either produced inside Malaysia or by neighboring countries which was later brought to Penang by monsoon wind.