The South Georgia Wave Experiment (SG-WEX)

Lead Research Organisation: British Antarctic Survey
Department Name: Science Programmes


Gravity waves are an important type of atmospheric wave. They play a key role in many atmospheric processes, ranging from convection to the mixing of chemical species to influencing the global-scale circulation of the stratosphere and mesosphere. Because of this, it is essential to represent their effects in numerical weather prediction and climate models.

Gravity waves are generated by sources including winds blowing over mountains, jet-stream instabilities and strong convection. The waves can transport energy and momentum away from these sources and deposit them at greater heights, thus exerting a significant "drag" on the circulation and so coupling together different layers of the atmosphere.

Recent studies have shown that isolated mountainous islands in regions of strong winds can be intense sources of gravity waves that can have climatologically-significant effects on atmospheric circulation. However, most climate and numerical weather prediction models cannot accurately model waves from such small, intense island sources because the islands are too small compared to the resolution of the models - this is the "small island problem".

Here, we propose a major coordinated observational and modelling experiment to determine the nature and impacts of gravity waves generated by the most important of all these islands, South Georgia in the Southern Atlantic.

Our experiment will answer the following questions:

1. What is the nature of gravity waves generated by South Georgia and what is their variability?

2. What is the contribution of these gravity waves to the total field of gravity waves over the South Atlantic?

3. What is the influence of gravity waves from South Georgia on the mesosphere?

4. How can these observations be used to improve gravity-wave parametrizations in models?

5. How important is South Georgia in comparison to other gravity-wave sources and how does it impact local winds and the development of synoptic systems?

To answer these questions we will make measurements of gravity waves over and around South Georgia in two radiosondes campaigns in which meteorological balloons will be launched from South Georgia. We will place these observations in context with measurements made by satellite across the whole South Atlantic. Significantly, we will also deploy the first atmospheric radar on South Georgia. This is a meteor radar that will make the first ever measurements of gravity waves (and winds, tides and large-scale planetary waves) in the mesosphere over South Georgia at heights of 80 - 100 km.

These experimental results will be complemented by a programme of modelling work that will explore the propagation of gravity waves away from their sources. The observations will be used to help guide the development of new, improved, mathematical representations of gravity waves (so-called "parametrizations") allowing such islands to be better represented in the Met Office's Unified Model used for numerical weather prediction and climate studies. Finally, modelling studies will integrate these studies and determine the relative importance of South Georgia compared to other waves sources and investigate the impact of
Gravity waves from South Georgia on local winds and the development of synoptic (weather) systems.

Planned Impact

There are three main groups of beneficiaries:

a) The academic community who work in tropospheric, stratospheric and mesospheric science. We will present our results and make a particular effort to bridge the gaps between experimental scientists studying different regions of the atmosphere and those modellers working in numerical weather prediction.

b) The general public, who will be informed of the nature of our project and kept up to date on its development by a dedicated web site and the Press Office and Public Engagement Unit of The University of Bath. The public will also ultimately benefit from the improvements in numerical weather prediction and climate modelling.

c) The Met Office, who will benefit by being able to use the knowledge generated by the project to assess and improve the representation of gravity waves in future Model development for numerical weather prediction and climate research.


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Description As a result of analysis of the two radiosonde observation campaigns in 2015 we have confirmed that short-period gravity waves are much stronger in the winter over South Georgia than in the summer months. This has not been observed directly before, only suspected.

One paper has been submitted as lead author, this data is used in a case study paper that brings together modelling, radiosonde and satellite data where I am a co-author. Another paper on radiosonde work is also being written.
Exploitation Route We hope that the findings will increase understanding of the role of small islands in contributing to the "missing" momentum flux over the southern ocean that is a problem in models.

The modelling component of this grant involves the Met Office so we hope to provide information to help improve the gravity wave parametrisations they use in their model.
Sectors Aerospace, Defence and Marine,Environment

Description DRAGON-WEX: The Drake Passage & Southern Ocean Wave Experiment
Amount £671,434 (GBP)
Funding ID NE/R001235/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 12/2017 
End 12/2020
Description Invited seminar (University Ireland - Maynooth) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact The BAS PI was invited to Ireland to give a seminar about the work she had been doing on the SG-WEX project to the physics department at Maynooth University. As a research group there has similar interests so there was lots of discussion about my work and their related projects.
Year(s) Of Engagement Activity 2015
Description Listed as a co-author on talks by other SG-WEX partners 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Talks were given at a Gravity wave SPARC conference by the Bath PI and PDRA on this grant, I was a co-author and provided data for them.

The Bath PI also gave an invited seminar where I was a co-author
Year(s) Of Engagement Activity 2016
Description outreach talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Was asked to give a talk to a local WI group. I spoke generally about Antarctica but also did a section on my work and included work from my SG-WEX presentations
Year(s) Of Engagement Activity 2018