| dc.description.abstract | Aerosols can alter the earth′s radiation budget and influence global climate change. To improve the understanding of aerosol optical properties (AOPs) and aerosol radiation effect (ARE), NOAA Federated Aerosol Network (NFAN) was established to monitor the mean values, spatiotemporal variability, and long-term trends of AOPs. Lulin Atmospheric Background Station (LABS, {23.469}^circle N, {120.874}^circle E, 2862 a.m.s.l.), which is located on the top of Mt. Lulin in central Taiwan, is one of the NFAN major sites in Asia. Although the NOAA aerosol system provides the state of art AOPs measurements, the lack of aerosol microphysics and chemical components information still remains a challenge for the ARE calculations. Therefore, the current study aims to develop an inversion of aerosol optical and microphysical properties (i.e., aerosol size distribution and the aerosol refractive index (RI)) based on Mie theory and aerosol in-situ measurements at the LABS.
According to the sensitivity experiment, the inversion method appropriate for the case of bimodal aerosol size distribution. The generalizing effective coverage was the fine mode of aerosol diameter <300nm or the coarse mode diameter <500nm, the real part of the equivalent refractive index (RRI) around 1.3 to 2.5, and the image part of the equivalent refractive index (IRI) around 10-4 to 1. Further, we selected two full months of April 2020 and March 2021 for implementing the inversion. As the observational results suggested by an aerosol-type classification method, the LABS was affected by the long-range transported dust and biomass burning aerosols in these two months. Base on the LABS’s realistic inversion, the monthly mean of biomass burning AOPs was around 0.77pm0.36 mu m for the aerosol equivalent diameter and around 1.82-i0.04 (1.62-i0.00 to 2.02-i0.08) for the aerosol refractive index in March 2021; The mean of dust AOPs was about 1.47pm0.63mu m for the equivalent diameter and around 1.48-i0.01 (1.40-i0.00 to 1.68-i0.03) for the aerosol refractive index in April 2020. The above results illustrate that the inversion method can well represent the variation of dust and biomass burning aerosol properties, and the growth of the aerosol diameter. Compared to the measurements of the results, it shows a good correlation (r>0.9), but underestimates the scattering coefficient of 12%, underestimates the absorption coefficient of 4%, and overestimates the mass concentration of 35%. A larger uncertainty (i.e., root-mean-square error) was shown for the absorption coefficient and mass concentration. In the future, our inversion could apply to the observation closure between different instruments, and help to intensify the integrity of the input data in the radiation transfer model, which can improve the ARE simulation. | en_US |