Meteorological Data from KLAWS-2G for an Astronomical Site Survey of Dome A, Antarctica

Abstract

We present an analysis of meteorological data from the second generation of the Kunlun Automated Weather Station (KLAWS-2G) at Dome A, Antarctica during 2015 and 2016. We find that a strong temperature inversion exists for all the elevations up to 14 m that KLAWS-2G can reach, and lasts for more than 10 hours for 50% or more of the time when temperature inversion occurs. The average wind speeds at 4 m elevation are 4.2 m s −1 and 3.8 m s −1 during 2015 and 2016, respectively. The strong temperature inversion and moderate wind speed lead to a shallow turbulent boundary layer height at Dome A. By analyzing the temperature and wind shear profiles, we note telescopes should be elevated by at least 8 m above the ice. We also find that the duration of temperature inversions, and the wind speed, vary considerably from year to year. Therefore, long-term and continuous data are still needed for the site survey at Dome A.

Astronomy from Dome A in Antarctica

“…With a full-year monitoring in 2011 from KLAWS, Hu et al (2014) found a strong temperature inversion existed for more than 70% of the time above snow surface, and up to 95% above 6 m. The temperature gradient was often greater than 10 • C from 0 m to 10 m. These were further confirmed with 20 month data from KLAWS-2G in 2015 and 2016 (Hu et al 2019).…”

“…Since katabatic wind dominates the Antarctica continent, the wind speed should be very low in general with random directions at Dome A. These were confirmed and an average wind speed of 1.5 m s −1 was recorded at 4 m in 2011 (Hu et al 2014), but it was about 4 m s −1 in 2015-2016 (Hu et al 2019). They concluded that the difference reflects the annual climatological change.…”

“…Although KLCAM was intact, two new redundant KLCAMs were deployed and replaced the old one to guarantee continuous long-term data collection and avoid any possible problems developed in the old one, such as the shutter lifetime. A new 15 m tall KLAWS-2G was set up and replaced the damaged one of only a 5 m tall mast remained, restoring its full power of profiling the boundary layer and vertical temperature inversion (Hu et al 2019).…”

“…Besides South Pole, there are several prominent high points on the ice cap, among which Dome A is the highest at an altitude of 4093 meters and located within 80 • S latitude circle. The winter temperature drops to between −50 • C to −80 • C while in summer it is seldom above −30 • C (Hu et al 2014(Hu et al , 2019. Table 1 lists the locations and altitudes of Dome A, C, F, and South Pole which are also marked on a map of Antarctica (Fig.…”

Multistar turbulence monitor: a new technique to measure optical turbulence profiles

“…At Dome A, most of the turbulence integral is contributed by the GL. The wind velocity in this layer is typically quite small, having a yearly average of 3 − 5 m s −1 (Hu et al 2014(Hu et al , 2019. For the AST3 telescopes, and a wind speed of 5 m s −1 , the characteristic time is T0 = 0.3 s. From Fig.…”