|
Integrated approach has been adopted at the ADvanced Environmental Research Center (ADEMRC), Gwangju Institute
of Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosol. Various active and passive
optical remote sensing techniques such as multi-wavelength (3β+2α+1δ) Raman LIDAR, sun-photometry, MAX-DOAS,
and satellite retrieval have been utilized. This integrated monitoring system approach combined with in-situ surface
measurement is to allow better characterization of physical and optical properties of atmospheric aerosol. Information on
the vertical distribution and microphysical properties of atmospheric aerosol is important for understanding its transport
characteristics as well as radiative effect. The GIST multi-wavelength (3β + 2α+1δ) Raman lidar system can measure
vertical profiles of optical properties of atmospheric aerosols such as extinction coefficients at 355 and 532nm, particle
backscatter coefficients at 355, 532 and 1064 nm, and depolarization ratio at 532nm. The incomplete overlap between
the telescope field-of-view and beam divergence of the transmitting laser significantly affects lidar measurement,
resulting in higher uncertainty near the surface where atmospheric aerosols of interest are concentrated. Differential
Optical Absorption Spectroscopy (DOAS) technique is applied as a complementary tool for the detection of atmospheric
aerosols near the surface. The passive Multi-Axis DOAS (MAX-DOAS) technique uses scattered sunlight as a light
source from several viewing directions. Recently developed aerosol retrieval algorithm based on O4 slant column
densities (SCDs) measured at UV and visible wavelengths has been utilized to derive aerosol information (e.g., aerosol
optical depth (AOD) and aerosol extinction coefficients (AECs)) in the lower troposphere. The aerosol extinction
coefficient at 356 nm was retrieved for the 0-1 and 1-2 km layers based on the MAX-DOAS measurements using the
retrieval algorithm. Ground-based measurements of tropospheric aerosol using multi-wavelength Raman lidar system
and a mobile MAX-DOAS system had been carried out at the Gwangju Institute of Science and Technology (GIST). To
evaluate the performance of the integrated measurement system (Lidar + MAX-DOAS), an aerosol retrieval method
called STAR (satellite aerosol retrieval) has been applied to compare the satellite AOD products with those based on the
Raman lidar and MAX-DOAS measurements. It allows complete monitoring of atmospheric aerosols' vertical profiles
for better estimation of their radiative effects on atmospheric environment and climate change.
|
