Dr Damian Murphy - atmospheric physicist
Scientists of the Antarctic: Dr Damian Murphy
I research the movement of air in the upper parts of the atmosphere, above what we would typically call the weather.
Atmospheric waves transfer momentum from the lower parts of the atmosphere into other parts of the atmosphere and, when they do that, they force large-scale circulations that can change the nature of the atmosphere.
These waves are made by airflow over mountains and landscape features, but they're also made by the air movements associated with cold fronts and changes in the jet-stream.
So the waves can be measured by making measurements of the wind using atmospheric balloons but also using atmospheric radars.
We operate three atmospheric radars at Davis station.
The three atmospheric radars look at different parts of the atmosphere. So one mostly looks at what we call the weather, so the troposphere and the lower stratosphere. It measures the wind speed in that part of the atmosphere every few minutes.
Another one looks quite high up in the atmosphere between about 70 and a hundred kilometres, in an area called the mesosphere and lower thermosphere. Once again, it does it every few minutes.
And then finally we have one that detects meteors as they come into the atmosphere, and the trail of the meteor gets blown along by the wind and we are able to measure the wind speed by gathering a whole stack of those detections of meteors.
Interestingly, that last radar can also be used to study the meteors themselves.A lot of the data taken is fed to the Bureau of Meteorology for them to use in their weather forecasting. The other radars are used by my colleagues all around the world for studying wave and other activity on a global scale around the Earth.
Dr Damian Murphy: BSc (Hons), MSc, PhD
The atmosphere moves in mysterious ways and my research has long been involved in trying to understand that movement, which is technically known as atmospheric dynamics. I came into this field through a remote sensing group at the University of Adelaide that used and developed atmospheric radars. These systems are now sophisticated enough to give us regular wind measurements at a range of heights through the lower and middle atmosphere. Investigations of atmospheric dynamics and its drivers were a natural progression of my PhD research, which focussed on the flow of momentum due to waves at heights above 80 km.
A post-doctoral fellowship with the Mawson Institute of Antarctic Research took me to Mawson Station for the winter of 1991 and introduced me to the challenge of radar remote sensing in Antarctica. Our program has met this challenge well with three radars now operating at Davis, sensing different parts of the polar atmosphere in different ways. Along the way I have researched waves that span large horizontal scales (planetary waves), atmospheric tides, and the localized waves generated by fronts, storms and mountains (gravity waves).
A recent focus on gravity waves has taken me into the world of atmospheric modelling. These waves are important for moving momentum around our atmosphere and, in the southern hemisphere, affect the background atmospheric structure in which the ozone hole forms. They are too small to appear naturally in climate models so they have to be introduced through a scheme called a parameterization. Recent observations of gravity waves have highlighted some of the shortcomings of existing parameterizations, something we need to fix if we are to be able to accurately model the ozone hole.
The ozone-hole induced changes in the dynamics of the stratosphere flow down to the earth’s surface to affect southern Australian weather in spring and summer. My work on parameterizations with colleagues in the USA, UK, Japan and Australia, which straddles the worlds of observation and modelling, will help us predict these and other changes to our weather and climate.
- Member - Scientific Committee on Atmospheric Research (SCAR) Action Group - Antarctic Gravity Wave Instrument Network (ANGWIN)
- National Center for Atmospheric Research, USA
- Utah State University, USA
- University of Tokyo, Japan
- National Institute of Polar Research, Japan
- Met Office, UK
- Monash University, Australia
- Bureau of Meteorology, Australia
García R.R., Smith A.K., Kinnison D.E., de la Cámara A. and Murphy D.J. (2017). Modification of the Gravity Wave Parameterization in the Whole Atmosphere Community Climate Model: Motivation and Results Journal of the Atmospheric Sciences 74(12) 275-291. doi: 10.1175/JAS-D-16-0104.1
Murphy D.J., Alexander S.P., Klekociuk A.R., Love P.T. and Vincent R.A. (2014). Radiosonde observations of gravity waves in the lower stratosphere over Davis, Antarctica Journal of Geophysical Research: Atmospheres 119(21) 11973-11996. doi: 10.1002/2014JD022448
Murphy D.J., Alexander S.P. and Vincent R.A. (2012). Interhemispheric dynamical coupling to the southern mesosphere and lower thermosphere. Journal of Geophysical Research 117 D08114, 14pp. doi: 10.1029/2011JD016865