Scientific objectives

The Davis VHF radar can be used to study a range of phenomena and so has the potential to contribute to many scientific investigations.

Investigations of Troposphere-Stratosphere-Mesosphere dynamics

The state of the lower and middle atmosphere is very much affected by the atmospheric waves embedded in it. They bring about day-to-day variations in the wind and seasonal variations in the temperature structure. An important category of these waves are known as gravity waves or buoyancy waves. They transport energy from the lower atmosphere to the upper reaches of the middle atmosphere and beyond.

The nature of gravity waves as they are produced, propagated and dissipated can be studied using the VHF radar through measurements of the wind at the range of heights the radar can probe. The wind variations that are attributable to gravity waves can be separated out and characterised. The turbulence, which is a natural end product of the waves when they break, and the mechanism that transfers their energy to background atmosphere, can also be considered.

The capability of VHF radars to measure winds below the middle atmosphere and closer to the earth's surface (in the troposphere) also has the potential to contribute to meteorology - the study of our weather.

Polar Mesosphere Summer Echoes (PMSE)

PMSE are a polar phenomena associated with the strength of radar returns from the summer mesosphere. Although some understanding of this phenomenon has come from northern-hemisphere observations, few southern observations of PMSE have been made. A characterisation of the Southern Hemisphere manifestation of this phenomenon and a comparison with the Northern Hemisphere will teach us much about PMSE and the atmosphere around them.

Meteor temperature studies

A more common example of the "shooting star" phenomenon is the sporadic meteor. These meteors are associated with the continuous rain of meteoric dust and the ionised trail they create as they pass through the mesosphere can be detected using a VHF radar. The rate at which the trail decays is related to the temperature. Using a small antenna array adjacent the main VHF radar, the decay rate and the height of the trail can be measured. It is simple to measure temperature variations using meteor trails, but some of the parameters required to calculate the absolute temperature are not well known. Some of the other temperature measuring instruments at Davis will help to improve our knowledge of this technique. It is hoped that measurements of mesospheric temperature through the summer period will then become possible.

A detailed description of the scientific objectives of the VHF radar project and how it contributes to the goals set by the Australian government is available under ASAC project number 2325.