The site survey in western China has been carried out since 2003. Remote studies and local surveys are performed,
and Oma site, Ali area in southwest Tibet, has been selected in 2005 to make site testing measurements. The
monitoring results show that Ali area can be the best choice for astronomical observations over the East Asian
regions. A new site in Ali has been identified and begun construction in 2010 for small telescopes and detailed
site characterization. This paper reviews the long term site survey, presents site characteristics in Tibet, and
introduces current status of the new Ali observatory.
The atmospheric turbulence characteristics are important to evaluate the quality of ground-based astronomical
observatory. In order to characterize Ali observatory, Tibet. we have developed a single star Scidar (SSS) system,
which is able to continuously monitor the vertical profiles of both optical turbulence and wind speed. The main
SSS configuration includes a 40cm telescope and a CCD camera for fast sampling the star scintillation pattern.
The SSS technique analyzes the scintillation patterns in real time, by computing the spatial auto-correlation and
at least two cross-correlation images, and retrieves both C2n (h) and V (h) vertical profiles from the ground up to
30km. This paper presents the first turbulence measurements with SSS at Ali observatory in October, 2011. We
have successfully obtained the profiles of optical turbulence and wind speed, as well as the key parameters for
adaptive optics, such as seeing, coherence time, and isoplanatic angle. The favourable results indicate that Ali
observatory can be an excellent astronomical observatory.