Calculation and statistical analysis of the fried parameter r0 of astronomical seeing in China

Using the sounding data in the years 1986–1995, the Fried parameter r0 at different heights over 81 radiosonde stations in China is calculated according to the theoretical model of Tatarski. The statistical results show that the annual mean r0 evidently depends on geographical position, and peaks of r0 occur in Xiahe Hezuo, Lijiang and Shanghai at height 3000 m, in Minqin and Guiyang at height 1500 m, in Hanzhong at height 900 m and in Dingri at the ground level of the station (4302 m). They also show that seasonal migration of geographical distribution of the monthly mean r0 is apparent and that it corresponds to the seasonal behaviour of the subtropical jet stream.