Atmospheric Physics Science Programme
The NCAS Atmospheric Physics programme draws on the strengths of UK Universities, particularly in small and mesoscale processes, to deliver a broad-ranging research portfolio addressing the need to better forecast the impact of weather phenomena on human activities. Concern about extreme weather events in a changing climate means there is real urgency to this area of research, reflected by its prominence in the NERC strategy. NCAS scientists work closely with each other and with their University groups to form teams addressing particular issues, often as part of wider projects such as NERC consortia or EU programmes. In this way the programme delivers science in a timely and effective fashion. We also collaborate with the Met Office and with international colleagues to ensure that our research is translated to progress in forecasting models and advice to the Government and public.
Modelling of synoptic-scale dynamics
The large-scale flow of the atmosphere is dominated by Rossby waves, which are excited by, and in turn themselves excite, weather systems. The predictability of the atmosphere over periods of 1-10 days depends on our ability to predict the generation, propagation and breaking of these waves. The NCAS Atmospheric Physics programme investigates the prediction of Rossby-wave regimes in global models, and seeks to better understand the effects of breaking Rossby waves on storm development and convection.
Modelling and measurement of convective and mesoscale dynamics
Weather forecasting models are beginning to represent the dynamics of the atmosphere at scales of a few kilometres. This brings a rich range of atmospheric phenomena that were hitherto parametrised or ignored into the models’ simulated fields. In turn, NCAS is using these models, together with coordinated field campaigns and long-term measurements, to better simulate convection and convective organisation, understand the effects of latent heat release on mesoscale dynamics, improve the prediction of extreme wind events in synoptic storms, elucidate the role of gravity waves in the generation of severe weather and determine the statistics of occurrence of extreme wind events.
Modelling and measurement of boundary-layer dynamics and structure
Small-scale processes cannot be explicitly forecast using current weather forecasting models, but they have direct effects on human activities. For example, NCAS is working to better describe the meteorology of cities, and the effect this has on air quality and building design. This includes developing improved modelling and measurement of urban canopy structure and turbulence, and of street canyon wind flow and pollutant dispersion. More generally, we use detailed field measurements to assess the effect of terrain on the local meteorology, leading to fundamental insights on stable boundary layers and improved models for orographic convection, and to investigate the effect of synoptic scale dynamics on stratocumulus clouds.
Modelling and measurement of micro-physical processes
Micro-physical processes in clouds determine cloud properties like lifetime and brightness, and are integral to the formation of precipitation. Mixed phase clouds – where ice and water coexist – present particularly complex problems and NCAS is using detailed field measurements to improve parametrisation of the ice phase in cloud models, to establish the role of aerosol in the maintenance and reflectivity of layer clouds and to correctly model the effects of aerosol on mixed phase clouds, including deep convective storms.
Modelling and measurement of pollution transport
The transport of pollution is determined by weather processes across all scales, from local dispersion in a street canyon to the global reach of winds in the free troposphere. The NCAS programme is developing improved measures of pollution transport in the vertical (through and out of the boundary layer), of the transport and mixing of pollutants by synoptic storms and of the transport of pollutants by deep convection into the upper troposphere.
Weather in a Future Climate
We will collaborate with the NCAS Climate programme to determine the consequences of natural climate variability and anthropogenic climate change for the occurrence of high impact weather events. As part of this work, we will explore the potential of nested regional climate modelling for impact assessment, in collaboration with NCAR, CEH and Rothamsted Research (BBSRC).