The atmospheric transparency of Telescope Array experiment from LIDAR

Abstract

UV fluorescence light generated by an air shower is scattered and lost along the path of transmission to the telescope. The main scattering processes are Rayleigh scattering by molecules and scattering by aerosols in an atmosphere.In the Telescope Array Experiment, we make use of LIDAR (LIght Detection And Ranging), which observes the back‐scattered light of laser. The LIDAR system is operated before the beginning and after the end of an FD observation, twice a night. The typical transparency of aerosols on clear night is obtained two years observation from September, 2007. The extinction coefficient of aerosols (αAS) at ground level are 0.040−0.013+0.036 km−1. The dependence of typical aerosols on height above ground level (1450 m a.s.l.) can be express by two exponential components as following: αAS(h) = 0.021 exp(−h/0.2)+0.019 exp(−h/1.9).The atmospheric transparency measured with the LIDAR system in TA site is discussed in this paper.