Engineering and the Environment, University of Southampton

Helen graduated from the University of Cambridge in 2001 with a BA and MSci in Natural Sciences (Physics), and again in 2006 with a PhD in experimental explosives physics. During this time she also worked at the University of Toronto in Canada and Los Alamos National Laboratory in the USA. A continuing fascination with the world of small-scale phenomena that happen too fast for humans to perceive led her from explosives to the study of ocean bubble formation. After three and a half years spent working in the USA (at the Scripps Institution of Oceanography, and the Graduate School of Oceanography at URI), she returned to the UK in 2010 as a research fellow at the ISVR. Her interests are the optics and acoustics of bubbles, the structure of the bubble plumes in breaking waves, and the influence of bubbles on air-sea gas transfer.

She’s also passionate about public engagement on scientific topics, and has extensive experience of public lectures and demonstrations, as well as science media work.   You can find out more about that here.

Ocean bubbles, bubble acoustics, air-sea gas transfer, ocean bubble optics

Why study bubbles?

Bubbles are an important component of the boundary between the ocean and the atmosphere.   The sea and the sky are both enormous, and anything that is exchanged between those two enormous things has to go through a very thin layer at the surface of the ocean.   And in lots of places (especially when it's very windy), that layer is full of bubbles.    In particular, bubbles help the exchange of different gases in both directions across the boundary, and they also spit tiny particles (aerosols) up into the sky.   These sorts of details are important in weather and climate models, and my aim is to provide to those models the basic information about how bubbles form and what they contribute.

My particular focus is the natural bubble coatings.  These change the way bubbles are formed and destroyed, and they have a strong influence on the bubble's ability to transport gases and particles.   I have laboratory experiments to study the fundamental physics of coated bubbles, and I go to sea to catch them in action.

See the Research Projects section below for details of specific projects.

The influence of surfactants on the mechanisms of ocean bubble formation

It is known that bubbles are important for the fluxes of gas and particles across the air-sea interface, as well as for the acoustical properties of the upper ocean and on ocean optics.   Currently, very little is known about the effect of natural surfactants on ocean bubble production, and the consequences of these surfactants for gas and particle fluxes.  The aim of this project is to understand the effects of surfactants on the detailed physics of bubble formation, and then to make measurements at sea to compare with the predicted physical changes.   The lab experiment is a tank built to watch bubbles fragment in turbulence.   The water properties (temperature, salinity, surfactant content and particulate content) can be varied to study bubble formation in different environment.   Acoustical and photographic data are used to follow many fragmentation events (usually 500-1000 for each set of conditions), and overall result is a set of fragmentation statistics.   This includes the frequency of fragmentation events, the number and size of bubbles produced in each event and some information about the dynamics of the events.   Comparing these will allow predictions for how bubble production under breaking waves will be affected by differing conditions, and this will lead to predictions for how gas and particle fluxes will also change.

Turbulent Exchange: Aerosols, Bubbles and Gases

This project is a collaboration between the University of Southampton and the University of Leeds.