Facilities and expertise


We develop and use an extraordinarily broad range of advanced models of atmospheric chemistry, aerosols, weather, climate and palaeoclimate. We lead the development of our own global atmospheric models and we are major users and developers of community models like the Met Office Unified Model and the NCAR WRF model. Model development and exploitation are also central to our strategic partnerships with NCAS and the Met Office Academic Partnership.

Global chemistry

ICAS is the owner and developer of the TOMCAT/SLIMCAT global Chemistry Transport Model, led by Prof Martyn Chipperfield and supported by NCAS as a national model. These models were key to the development of our understanding of the stratospheric ozone hole and predictions of how it will recover. A wide range of other applications include simulating how forest fires affect Arctic climate, understanding how natural halogen species are transported to the stratosphere, and understanding long term trends in global air pollution. ICAS also makes significant use of other international global models as appropriate, such as WACCM to study chemical processes in the mesosphere.

Global aerosols

The Global Model of Aerosol Processes (GLOMAP) is an extension of the TOMCAT CTM, and has supported the research of over 20 PhD and postdoc scientists over the last 5 years. GLOMAP research focuses on developing a deep understanding of how aerosol particles behave in the atmosphere, and how they affect climate. GLOMAP has enabled many advances in our understanding of global aerosols, including nucleation of new particles, the global sources of cloud condensation nuclei, natural emissions and the impacts on climate, and volcanic impacts on health. GLOMAP is also a key component of the UK Earth-system model (HadGEM) and the ECMWF Integrated Forecasting System.

Global Climate and Palaeoclimate

ICAS is a major centre for the development and use of the Unified Model (UM) for climate research, greatly facilitated through our Academic Partnership with the Met Office. We use the UM in its climate configuration (HadGEM), including development of the aerosol model GLOMAP-mode for climate applications. ICAS also has a long track record of innovative palaeoclimate studies with the UM, leading to important discoveries ranging from the origin of the Greenland ice sheet to the causes of ice-age extinctions. 

Related pages: Physical climate change, Palaeoclimate group, Biosphere processes group


ICAS is pushing the limits of how high resolution model simulations can be used to understand the development of complex weather systems. We make particular use of the global Unified Model nested down to scales of a few km. We also make extensive use of NCAR's WRF model and have a long track record of advanced modelling of air flow over complex terrain with models like BLASIUS. With these developments, we have begun to understand how complex systems like the West African Monsoon interact with the land surface, how dust storms are initiated through gust fronts, and how tropical precipitation is affected by deforestation. These developments are now being combined with our knowledge on aerosols to understand how air pollution affects precipitation. 

Related pages: Atmosphere and cloud dynamics

Clouds and precipitation

Understanding how clouds and precipitation will change in a future climate presents an enormous modelling challenge. To tackle this problem ICAS is developing new capability to couple the effects of aerosols in the nested high resolution version of the Unified Model. We also use detailed aerosol-cloud microphysics models like MAC3 and the Met Office Large Eddy Model (LEM) which we have used to study thunderstorms, warm rain formation, ice phase processes and aerosol effects on all of these processes.

Related pages: Thunderstorms and precipitation, Aerosols and clouds, Weather systems

Climate impacts on agriculture

ICAS is the owner and developer of the General Large-Area Model for annual crops. GLAM is a tool for assessing the impacts of climate variability and change on annual crops. It has been designed for use with regional and global climate model output and remotely sensed data. GLAM has a growing user community and the model is under continuing development.

Related pages: Climate impacts