Project Description

Large convective systems affect the regions around them in two important ways.

• Cold pools or density currents form when rainfall evaporates below the cloud. The evaporation cools the air, causing it to descend and spread across the surface.
• Gravity waves form when warm air rises and disturbs stable layers of air above. As these layers return to their level of neutral buoyancy they cause waves that spread outwards, like ripples on a pond.

Both these mechanisms generate vertical motion in the atmosphere around the initial storm. This can trigger new storms to form or influence the motion of the original storm. These mechanisms influencing storm triggering and movement are difficult to represent in our weather and climate simulations, as the resolution needed to represent them is very fine. Measuring these mechanisms allows the development and assessment of our simulations.

This project will use an array of extremely sensitive microbarometers to measure cold pools, gravity waves and other moving features. These microbarometers measure the small pressure changes as a feature passes over, and by spreading the sensors over a wide region, we can determine the speed and direction in which the feature is moving. Combining this with temperature and humidity measurements, we can distinguish between gravity waves, cold pools and other features.

Data has already been collected in the UK using the microbarometers as part of the Wessex Convection – Observing the Evolving Structures of Turbulence (WOEST https://science.ncas.ac.uk/woest/) project. The PhD project would begin by analysing this data to gain insight into convective systems in the UK. The instruments will be deployed as part of the Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment (TEAMx https://www.teamx-programme.org/). In that project, they will help to characterise drag caused by large mountain ranges.

We will deploy the instruments again as part of this PhD project, either in the UK or overseas. Deep tropical convection is an exciting potential next target. Convection over the Maritime Continent drives global weather patterns. Large convective systems associated with the African Monsoon bring rainfall to the Sahel and force hot, dusty air out of the Sahara. Convection over East Africa causes a risk to life and property, particularly to fishing boats on Lake Victoria. Any of these regions could be a suitable location for deploying these instruments.

This project would suit a candidate who is interested in data analysis, coding, practical measurements and fieldwork. There will probably be an element of overseas fieldwork involved in the project, so it is important that a prospective candidate is willing and able to travel.

Suggested Reading

Morphology and growth of convective cold pools observed by a dense station network in Germany

Convective Cold Pools in Long-Term Boundary Layer Mast Observations

Ten year observations of gravity waves from thunderstorms in western Africa

Wessex Convection Experiment (WesCon)

Wessex Convection – Observing the Evolving Structures of Turbulence (WOEST)

Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment (TEAMx)