Atmospheric turbulence above Dome A from a sonic radar

Snodar sent out an acoustic pulse at about 5 kHz, and listened for the echo. The directories here are: /papers PDFs of papers and a PhD thesis describing the instrument and results /2009_Data_analysis Reduced data /snodar Raw data /snodar09 Raw data /extracted Raw data The raw data contain echo strengths, and are in files with names similar to the following: output/SNODAR_DATA_1203077424_265709 output/RAW_SNODAR_DATA_1255074792_749298 The filenames end with the UNIX time epoch (in seconds, followed by microseconds after the "_") of the start of the observation.

There are also some WAV files such as: snodar-1205534620.wav.bz2 which contain the raw acoustic echoes from the Snodar. Snodar was first deployed to Dome A in early 2008. It measured a stable diurnal boundary layer with a minimum height of 9 m and a maximum height of 89 m between the 10th and 14th of February 2008.

A minor electrical failure crippled the instrument after 12000 samples. The instrument could not be repaired until 2009 as Dome A is an unmanned site. A second-generation of Snodar was deployed to Dome A in January 2009 and included several modifications to expand its capabilities and increase its robustness.

The modifications included a new antenna design to hinder frost formation. The 2008 Snodar was also upgraded and as such there were two Snodars operating simultaneously at Dome A during 2009, with a separation of approximately 20 m. The agreement between the two instruments was extremely good.

The data files are a "1" or "2" in their filenames to distinguish them. The pre-2009 Snodar is number 1. The reduced data are in the form of CSV files showing boundary layer height and UNIX epoch, with postscript plots.

See the matlab file "2009_Data_analysis/monthly_anal.m for" the data analysis program. Sub-folders within "2009_Data_analysis" show results with alternative definitions for the boundary layer height. For help, email Michael Ashley <m.ashley@unsw.edu.au> and/or Colin Bonner <c.bonner@fulcrum3d.com>.