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Although technology has advanced in the past few decades, the understanding of the effect of aerosol on Earth’s climate has remained largely unknown. Even if considerable effort has been made by researchers around the world to study this pressing issue, the non-uniform distribution of aerosols is still a huge challenge on global aerosol characterization studies. Without extensive and reliable measurements from most regions in the world, a complete understanding of aerosol characteristics cannot be achieved. In this study, a Raman LIDAR was used to acquire data to calculate the range-dependent extinction-to-backscattering ratio during a very particular period: when the Northeast monsoon season shifts to the Southwest monsoon season. During this time period, monsoonal winds change direction, leading to changes in aerosol type and properties above Penang Island due to the global atmospheric circulation. From the retrieved extinction-to-backscattering ratio, it is possible to differentiate the aerosol types present at various altitudes. It was found that background marine and urban aerosols were present above Penang Island, as marine and urban aerosols were present both below and above the PBL height regardless of the monsoon season. Additionally, biomass burning aerosols and aged forest fire aerosols were occasionally found, which were normally associated with cases of pollution, such as those in early March 2014 and June 2014. Finally, it was found that during a haze episode, the entire atmospheric column was dominated by wood burning aerosols. AERONET sunphotometer data have been used to validate LIDAR findings. Radiative effect of background and transported aerosols are evaluated with the Fu-Liou-Gu radiative transfer model.

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 t...

Haze is a phenomenon which occurs when there is a great amount of tiny particulates suspended in the atmosphere. During the period of March 2014, a long period of haze event occurred in Penang, Malaysia. The haze condition was measured and monitored using a ground-based Lidar system. By using the measurements obtained, we evaluated the performance of the ECMWF MACC-II model. Lidar measurements showed that there was a thick aerosol layer confined in the planetary boundary layer (PBL) with extinction coefficients exceeding values of 0.3 km−1. The model however has underestimated the atmospheric conditions in Penang. Backward trajectories analysis was performed to identify aerosols sources and transport. It is speculated that the aerosols came from the North-East direction which was influenced by the North-East monsoon wind and some originated from the central eastern coast of Sumatra along the Straits of Malacca.

This paper has been withdrawn by the publisher because it was not presented at the conference.

During 24th July 2013 to 1st August 2013, a haze event struck Penang Island, causing the visibility to decrease and increase in Air Pollution Index (API). A ground-based backscatter Lidar, operate at 355 nm which was setup at the roof top of the School of Physics, Universiti Sains Malaysia. It was used to monitor and investigate the haze event. For this work, we studied the daytime variation of the aerosol intensity, distribution, planetary boundary layer (PBL) height and the aerosol optical depth (AOD) values during these days. We found that the aerosol are very intense during the first two days of the haze event and slowly decline as time passed. Finally the haze event died off on 1st August 2013. As for daily aerosol distribution, aerosols are generally more intense during the afternoon. Its intensity is slightly lower in the morning and evening. Similar trends were observed for AOD values as they increase from morning to afternoon and slowly decrease in the evening. Most aerosols are found contained below the PBL which generally found at around 1000 – 2000 m in height.