High resolution remote sensing of the atmospheric boundary layer over Antarctica

• Main Author: Bonner, Colin
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: UNSW Sydney 2017
• Subjects: boundary layer; Sodar; Antarctica; remote sensing; seeing; Antarctic; Dome Fuji; The Antarctic; Antarc*
• Online Access: https://dx.doi.org/10.26190/unsworks/19804; http://hdl.handle.net/1959.4/58362

At altitudes of up to 4100m, the Domes of the Antarctic plateau provide unique opportunities for ground-based astronomy. In addition to excellent atmospheric windows and extended periods of darkness, the Domes exhibit extremely favourable distributions of atmospheric turbulence: nearly all the turbulence that affects ground-based telescopes is contained within the lowest few tens of metres. By 2004 it was known that the third highest location on the Antarctic plateau, Dome C, had nearly all the atmospheric optical turbulence confined to within 30m of the ground. Above this, exceptional free-air median seeing of 0.23 arc-seconds is experienced. Such conditions are superior to the current gold-standard temperate latitude sites of Mauna Kea, La Palma and Paranal. The purpose of this research is to characterise the height of the thin but intense turbulent boundary layer at the highest location on the Antarctic plateau, Dome A. This information is needed to plan towers for future 2m and larger optical/infrared telescopes, thereby giving access to the exceptional free-air seeing. The characterisation of the boundary layer at Dome A was achieved with a high resolution SODAR that we have called the Surface Layer Non-Doppler Acoustic Radar, or Snodar. Snodar characterised the Dome A boundary layer from 2009 to 2011 and measured the median winter boundary layer height to be just 12.2m. The success of Snodar at Dome~A resulted in a total of seven Snodars being built. One Snodar was sent to Dome~Fuji---the second highest peak on the Antarctic plateau. Another was sent to the Subaru Telescope on Mauna Kea, to better understand the turbulence around the telescope. Two Snodars are currently en-route to Tibet for site testing for a future large telescope. This thesis presents the design of Snodar and ancillary instrumentation for calibration and field verification, Dome~A observations from 2009 to 2011, Dome~Fuji observations from 2011, and a comparison of Snodar data with thermal profiles from a highly-instrumented meteorological mast. The thesis also presents a procedure to calibrate Snodar against a mast-mounted sonic anemometer, and the results of such a calibration performed at Mauna Kea Observatory.