vhf atmospheric and meteor radar installation at davis, antarctica

ased upon a geotechnical engineering assessment to protect the array from possible damagedue to permafrost and annual freeze and thaw cycles. The 3-element Yagi antennas that makeup the array were attached to their vertical 50 mm diameter support posts at varying heightsabove the ground so as to set the plane of their driver elements horizontal. The posts ranged inlength from 2 to 4 metres. The posts were supported at their base by concrete blocks designedto prevent translation and rotation. The strain caused by wind loading on the antennas andposts was taken up by a system of guy ropes. Concrete blocks were placed on small pads ofun-reinforced concrete approximately 800 mm x 800 mm x 250 mm. These provided an evensurface to support the blocks and were oversized to allow the block to be moved into thecorrect position on the pad. The guy system consisted of a network of ropes at the height ofthe top of the poles. After tensioning, the guy ropes were secured to anchor points at the endsof each row and column of antennas. After setting each support post to vertical, the top ofeach post was clamped to an East-West and a North-South aligned guy. The rope used was a‘braid’ made of fibre that has a high strength and a low stretch factor. The radar module haspower and fibre optics communications to the main station network.Radar Operating Schedule for the 2003 Austral Winter with Preliminary ObservationsFigure 2. Horizontal windmeasurements in themesosphere and lowerthermosphere obtained withthe VHF radar operating inmeteor mode.Through the Antarctic winter, the VHF radar schedule emphasises detection of meteor echoesfrom the mesosphere and lower thermosphere. These echoes are to be used, in conjunctionwith other instruments at Davis, for wind and temperature comparisons. However, soundingsof the lower atmosphere are carried out every 12 minutes. The frequency and duration oflower atmospheric soundings was later increased to every 6 minutes for two hour intervalsfollowing ozone-sonde and standard sonde balloon releases.Figure 3. Direction ofarrival for meteordetections on 30 April2003 at Davis.