Observations and Predictions of Heavy Convective Precipitation
Supervisors: Professors Alan Blyth and Chris Collier, Drs. Peter Knippertz and Alan Gadian
Enquires: A.M.Blyth(at)leeds.ac.uk
Forecasting the amount of precipitation from convective storms is an important problem. Weather forecast models do quite well in pin-pointing where the storm will form, but they have a harder time with the amount of precipitation. The uncertainty can result in poor forecasts of flash floods and strong winds from convective storms and also of the behaviour of mesoscale structures in extratropical storms that have embedded convection. This PhD project is a unique opportunity to understand the cloud microphysical processes and, importantly, the interaction between the dynamics and microphysics. The research is motivated by two field projects: DIAbatic influence on Mesoscale structures in ExTratropical storms (DIAMET) that is focussed on understanding and improving the prediction of mesoscale structures in synoptic-scale storms; and the COnvective Precipitation Experiment (COPE) designed specifically to study the quantity of precipitation in convective clouds. COPE is being performed in collaboration with the Met Office and several international partners.
The focus in DIAMET is on the understanding and prediction of mesoscale structures in synoptic-scale storms (see left). Such structures include fronts, rain bands, secondary cyclones, sting jets etc., and are important because they produce much of the extreme weather experienced at the surface (e.g. strong winds, heavy rain). Understanding the production and development of these structures involves studying the interaction between the dynamics and microphysics in the embedded convective clouds. The growth and evaporation of particles, which results in latent heat exchange, is particularly important.
The focus of COPE is on isolated thunderstorms or storms that form along a line (see right), but also involves heavy precipitation and the interaction between microphysics and dynamics. The key aspects of COPE are: (1) The spatial and temporal distribution of water vapour, temperature and structures such as convergence lines in the boundary layer, and the environmental stability; (2) The particles supporting cloud condensation and ice formation ingested into the clouds; (3) The precipitation process involving both collision and coalescence and ice particles; (4) The dynamics and microphysics of clouds, including entrainment of environmental air from the cloud edges and mixing, downdraft formation and storm persistence. COPE will address all of these by making intensive observations in a tightly focussed field campaign that addresses the whole lifecycle of convective cloud systems that form in the confined geographical area of the southwest peninsula of England.
There is an opportunity to fly on the UK research aircraft, the FAAM BAe 146 and to use state-of-the-art instruments, such as the new FGAM mobile radar (see left). The student will analyse the data gathered with the cloud physics instruments on the aircraft during the flights in conjunction with data from the radar. The student would also use high-resolution cloud models such as the UK Met Office Unified Model (UM) and the Weather Research and Forecasting (WRF) model to help interpret the data.