| dc.description.abstract | ABSTRACT
Aerosol types play an important role for air pollutant tracking, satellite retrieval, and atmospheric radiation calculation. In addition, East Asia is the most complex region of aerosol type in the world, and aerosols type classification could be challenge for this region. Pervious studies proven that the extinction to backscatter ratio (lidar ratio, Sp) can be applied to distinguish aerosols types effectively. Therefore, this study focus on studying the relationship between aerosol types and aerosol optical properies. We analyzed long-term data of Sp and other optical properties. Information of the aerosol vertical uding distribution and air mass trajectories was used to clarify our founding.
Eight years (2005-2012) of EPA-NCU Micro-PulseLidar observationswere applied in this study. Seasonal variation of aerosol optical depth (AOD) shows highest AOD (~0.8) in Mar, about two times higher than average value of 0.4. The high AOD in spring is attributed to long-range transport of biomass-burning aerosols from Indochina According to aerosol profile classification, extinction profiles were classified into two types: Type 1 (near-surface aerosol transport) and Type 2 (double layer aerosol transport). Fall season (Oct-Nov) is the prevailing season for the Type 1, whereas Type 2 mainly happened in spring (Mar-Apr). In type 1, air masses were travelled from 3 sectors: Asia continental (AC), Pacific Ocean (PO), and Southeast Asia (SA). The mean Sp values for the three sectors are 3917sr for AC, 3012sr for PO, and 3818sr for SA. According the meaning of Sp, a low Spimplies a stronger scattering characteristic. The Sp results suggest aerosol from AC sector contain dust particle, and aerosols from PO are most likely sea-salt. We further combine the EPA dust event database and backward trajectory analysis for Type 2. Results show that Sp is 4114sr for dust storm events. The histogram of Sp for biomass burning events in Type 2 shows two peaks pattern. The first peak occurred within range of 30-50sr corresponding to urban pollutant, whilesecond peak occurred within range of 60-80sr in relation to biomass burning. Finally, our study summarized the Sp values for four major aerosol types over NCU：Urban (4218sr), Dust (346sr), Biomass burning (6912sr), Oceanic (3012sr). The relationship between Sp and aerosol types based on our study can be applied to air pollutant monitoring. | en_US |