Inter-comparison between the Aerosol Optical Properties Retrieved by Different Inversion Methods from SKYNET Sky Radiometer Observations over Qionghai and Yucheng in China

Abstract. This study analyzed the aerosol optical properties derived by SKYRAD.pack versions 5.0 and 4.2 using the radiometer measurements over Qionghai and Yucheng in China, two new sites of the sky radiometer network (SKYNET). The volume size distribution retrieved by V5.0 presented bimodal patterns with a 0.1–0.2 μm fine particle mode and a 5–6 μm coarse particle mode both over Qionghai and Yucheng. The differences of the volume size distributions between the two versions were very large for the coarse mode with a radius of over 5 μm. The mean values of single scattering albedo (SSA) at 500 nm retrieved from V5.0 were approximately 0.02 lower, but 0.03 higher than those from V4.2 in Qionghai and Yucheng, respectively. The average imaginary part of the complex refractive index (mi) retrieved from V5.0 at all wavelengths was systemically higher than those by V4.2 over Qionghai. Moreover, the differences between the real parts of the complex refractive index (mr) obtained using the two versions were within 4.25 % both at Yucheng and Qionghai. The seasonal variability of the aerosol properties over Qionghai and Yucheng were investigated based on SKYRAD.pack V5.0. The seasonal average SSA during the winter was larger than those in other seasons in Yucheng, while the lowest SSA values occurred in winter over Qionghai. Meanwhile, the mr showed a minimum in winter over both sites. The results can provide validation data in China for SKYNET to continue improving the data-processing and inversion method. The results provide valuable references for continued improvement of the retrieval algorithms of SKYNET and other aerosol observational networks.