Details of Award
NERC Reference : NE/N008219/1
The scaling behaviour of cumulus updraughts
Training Grant Award
- Lead Supervisor:
- Professor A Blyth, University of Leeds, School of Earth and Environment
- Grant held at:
- University of Leeds, School of Earth and Environment
- Science Area:
- Atmospheric
- Overall Classification:
- Atmospheric
- ENRIs:
- Environmental Risks and Hazards
- Global Change
- Science Topics:
- Boundary Layer Meteorology
- Water In The Atmosphere
- Abstract:
- The representation of convective clouds is one of the major uncertainties in weather and climate models. Projections of global temperature change, tropical rainfall and summertime thunderstorms all critically depend on an accurate description of such clouds. Predicting these clouds is particularly challenging, as large-scale weather models and climate models work with grid spacings of 20 to 200 km, and cannot represent individual clouds. A statistical representation, or parametrisation, of clouds is therefore needed. The goal of this project is to improve the parametrisation of the parts of these clouds which undergo rapid upward vertical motion. These updraughts provide most of the heat and moisture transport in the cloud and intense precipitation also forms in the updraughts. We will use a very detailed model (the Met Office NERC cloud model, MONC) with a grid spacing of around 25 meters, to look into the behaviour of these clouds. Such a model can be thought of as a virtual laboratory, in which the fundamental fluid dynamical equations for each cloud are explicitly solved. MONC is based on previous work at the Met Office, but has been fully rewritten to exploit recent increases in supercomputing capabilities, where simulations are performed on hundreds or even thousands of computer cores. This makes it possible to simulate a group of cumulonimbus clouds at high resolution. The way in which updraughts interact with the surrounding environment is one of the main uncertainties. The parameters that determine the vertical velocity of the updraught and the rate of mixing between cloudy and environmental air are not well understood. The current project aims to investigate these processes in order to improve their representation in the Met Office operational models. We will do this by systematically exploring the response of clouds to changes in e.g. the humidity of the surrounding air, the vertical temperature profile, and the size of the cloud when it initially forms. Recently, there has been interest in the atmospheric science community in describing clouds as thermals, which are unsteady rising currents of warm air, rather than as steady plumes. The behaviour of thermals has been studied by physicists in the past, but the role of e.g. condensation and evaporation in clouds and the change of environmental conditions with height are not well understood. We will explore if existing theoretical models can be adapted to take account of these issues, and if the behaviour of thermals can be used as a better paradigm for parameterisation. This can be explored by performing numerical experiments with a simplified version of the operational model of the Met Office. The Met Office is an active CASE partner, and the strong collaboration will ensure that the developments in this project will contribute to ongoing work to improve the convection parametrisation scheme in operational models, undertaken by industrial supervisor Dr Alison Stirling's group.
- NERC Reference:
- NE/N008219/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Industrial CASE
This training grant award has a total value of £91,361
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - RTSG | Total - Student Stipend |
|---|---|---|
| £18,014 | £11,000 | £62,349 |
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