Lidar ratio (LR) is an important parameter to invert the lidar equation to subsequently get information from the lidar
signals. Therefore, it is the objective of this study to assess the LR values for each day to implement into the inversion
method. An algorithm has been generated to estimate the lidar ratios in Penang for the Raymetrics ground-based lidar.
Daily average humidity and visibility parameters was obtained and the lidar ratios for each day in year 2014 and year
2015 were assessed. It is found that the LR values in the year 2014 and 2015 generally lie in the range from 55 sr to 85
sr. Maximum LR values in the year 2014 and 2015 is 141 sr and 177 sr respectively. Both years has the same minimum
LR value of 46 sr. Extreme values are found in both years during the haze events that occurred in Penang. The LR
values estimated are valuable as they represent the atmospheric conditions in Penang and plays an utmost important role
in the lidar inversion method.
The atmosphere over Penang Island is monitored for one year using a ground based Lidar. The Lidar signals are processed to obtain the AOD, extinction coefficients and the PBL heights to provide an overview of the atmospheric conditions in Penang. The data are averaged daily and plotted for the year of 2014. The AOD and extinction coefficients display seasonal trends that increase during the monsoon seasons (Southwest monsoon and Northeast monsoon) and decrease during the inter-monsoon seasons. During the monsoon seasons, a mixture of clear and hazy atmospheric conditions is found due to the presence of rain which removes the particulates or aerosols from the atmosphere. If no rain occurs, aerosols transported over Penang will stay in the atmosphere and be removed after a certain period. The average AOD is 0.4034 for year 2014 with a maximum of 1.0787 on a hazy day and a minimum of 0.0354 on a clear day. The extinction coefficient range is quite wide especially during the monsoonal months owing to the intervention of aerosol layers in the atmosphere of Penang. A clear day will have a smaller range of extinction coefficients. The planetary boundary layer has an average height of 0.878 km. Thicker PBLs are found after monsoon seasons as the aerosols has sunk to the earth surface from higher altitudes. The PBL has an opposing trend to the AOD and extinction coefficients. The atmosphere over Penang Island consists of a mixture of marine particles and fine particles that are mainly transported to Penang by the monsoon winds from the surrounding sea and biomass burnings in the neighboring SEA countries. An overview of the atmospheric conditions in Penang for a whole year is meaningful for further research.
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