Sun-sky radiometer observation network with the extension of multi-wavelength polarization measurements

Focusing on the important role of ground-based sun radiation and aerosol observation in the fields of climate change,atmospheric environmental monitoring, and earth observation, we established a Sun-sky radiometer Observation NETwork( SONET) in typical Chinese regions by applying multi-wavelength polarimetric observation techniques. We present the following in this paper:( 1) the characteristics,measurement,principles,and functions of the multi-wavelength polarization radiometer and the establishment of SONET in typical Chinese regions with a brief introduction of the observation sites;( 2) observation patterns of sun-sky radiation and polarization as well as measurement parameters under direct sun,solar principal plane,and almucantar geometries;( 3) calibration of solar irradiance,sky radiance,and degree of linear polarization measurements and data processing methods for aerosol and water vapor,with illustrations of typical SONET observation under clear and hazy conditions;( 4) establishment of urban,rural,and haze aerosol type models of the total column atmosphere based on long-term continuous remote sensing observation in typical sites in China. On the basis of extension of multi-wavelength polarization measurements,SONET was employed to develop operational techniques for the network of sun-sky radiometers,including automatic observation,fast data processing,and regular calibration and maintenance,which contribute to the construction of atmospheric aerosol type models,retrieval and validation of satellite aerosol products,and remote monitoring of the atmospheric environment.