A ship-borne imager: determining mesospheric gravity wave activity above the ocean

Gravity waves are buoyancy waves in the atmosphere. They can be produced from a variety of sources, e.g. wind flowing over mountains or large weather systems. As they propagate upwards they become unstable and break (similar to waves on a beach) depositing their energy and momentum, driving the circulation and temperature patterns in the atmosphere. The region between 50km and 90km in altitude, known as the mesosphere, is dominated by gravity wave activity. In order to accurately reproduce their effects in atmospheric climate models, we need to observe gravity waves (and identify their sources) from all areas of the planet. As the oceans make up 70% of the Earth's surface it is vitally important to understand the gravity wave activity that occurs over them.

Traditionally satellite observations are used to obtain global estimates of gravity wave activity in the atmosphere but, they have limitations in that they cannot view the whole range (full spectrum) of gravity waves. This proposal looks to finalise development of a ship-borne imager that will allow gravity wave measurements of the mesosphere to be made from the R.R.S. James Clarke Ross as it traverses the Atlantic Ocean to and from the Antarctic and the U.K. These measurements will provide a unique insight into a different section of the gravity wave range to that which satellites can observe.

The ship-borne imager will use a novel system of 3 one-degree field of view imagers (radiometers) and the pitch and roll of the ship to scan the sky. The imagers will be observing gravity wave perturbations in a layer of airglow at around 90km altitude. Airglow is the term given to the weak emission of light by different gas layers in the atmosphere. As gravity waves pass through this airglow layer they alternately compress and rarefy it, resulting in a variation in the airglow emissions. Using these observations it is possible to determine the characteristics of the gravity waves.

We propose to exploit the ships isolation from land-based gravity wave sources and the ships itineraries to do case studies and examine two influences on the mesospheric gravity wave field: large weather systems in the deep ocean and topography.

The development of a ship-borne imager and the resultant measurements of mesospheric gravity waves will have the potential for both economic and societal impacts. There is the development of novel technology, which has the potential to be commercialised, and the gathering of data in a manner that makes it suitable for use in public engagement activities.

Consultation with the NERC innovation team has identified the ship-borne imager system as having the potential for commercialisation. The development and production of the ship-borne imager system will impact on BAS, NERC and the company producing the system. These impacts will be both economic and the transfer of knowledge for the benefit of all involved. The end users of such a commercialised product will primarily be other academic institutions with an interest in observing gravity waves above the oceans.

The Public Attitudes to Science study 2011 (commissioned by Department for Business, Innovation and Skills (BIS)) found that more than half the public wants to hear and see more information about science than they currently do. The survey also suggests that there are certain demographic groups that tend to be less engaged with science, so represent priorities for engagement. These include young people aged 16-24. The nature of the research done within this proposal (the measurement of gravity wave activity above the oceans and links to the atmosphere below) and the manner in which it is gathered (on a ship travelling to the Antarctic) makes it very suitable for use in public engagement as it is something people can visualise and relate to, unlike an abstract theory. Discussions with the BAS Press, Public Relations and Education Office have determined that an interactive computer-based demonstration with a small poster presentation alongside would be very suitable to include in BAS's activities as part of the popular Cambridge Science Festival. This free festival attracts over 35,000 people over two weeks of all ages. This will be a perfect opportunity to provide scientific information to the general public, including those highlighted in the BIS study, in an interesting manner. An interactive display, using Google Earth software, allows two-way engagement with the public, making the communication of the science and its importance much more informal, accessible and easier to understand. This work will benefit the public by helping them to understand the importance of atmospheric research, its links to climate science and enable them to learn about science in a fun way.