Introduction of a Sun/Sky-Radiometer Observation Network with the Extension of Multi-Wavelength Polarization Measurements in China

Sun/sky-radiometer is a type of ground-based remote sensing instrument which plays an important role in sun radiometry and aerosol observation in fields of climate change, atmospheric environment and earth observation. A worldwide network, known as AERONET, is initially built in 1993 and now composed of overpass 500 sites. For us, the new type of polarized sun/sky-radiometer is applied by using multi-wavelength polarimetric measuring techniques, and a Sun/Sky-radiometer Observation NETwork (SONET) has been established in China. SONET provides an long-term and reliable observation for remote sensing of aerosol optical and microphysical properties. In this paper, we introduce (i) characteristics, principles and functions of the multi-wavelength polarization radiometer and basic information about distributed field sites of SONET in Chinese typical regions; (ii) running modes, as well as parameter settings, of sun/sky radiation and polarization measurements under direct-sun, solar principal plane and almucantar geometries; (iii) calibration methods we use for solar irradiance, sky radiance and degree of linear polarization measurements, and data processing of aerosol and water vapor products together with examples under clean and haze conditions; (iv) the total column atmospheric aerosol models (urban, rural and haze models) derived from long-term continuous observation at typical sites in China. On the basis of extension of multi-wavelength polarization measurements, we also have developed other operation techniques of sun/sky-radiometer observation network including automatic observation, quick data processing, routine calibration and maintenance, which can contribute to construction of typical atmospheric aerosol models, retrieval and validation of satellite aerosol products and monitoring of atmospheric environment.