What I do

My research involves the use of state-of-the-art numerical models, run on supercomputers, to study the processes controlling the present state of the atmosphere and its evolution. A NERC Unit, the Atmospheric Chemistry Modelling Support Unit, is incorporated into the group.

Current research activities include:

Stratospheric Modelling

The chemistry, dynamics and radiative transfer of the stratosphere are being studied using a number of numerical models. Three particular problems being tackled are (i) the rapid depletion of ozone found recently in the polar spring, the so-called 'ozone hole', (ii) the more gradual decline in northern hemisphere ozone levels (which we have recently ascribed partly to long-term changes in atmospheric flow, and (iii) the effect on stratospheric ozone of increasing concentrations of CO₂, CH₄, N₂O and the chlorofluorocarbons.

Tropospheric Modelling

We have developed a range of models for studying the chemistry of the lower atmosphere, from complex 3D models to models based on air parcel trajectories. A major research theme is the changing oxidizing capacity of the troposphere (the ability of the troposphere to cleanse itself of pollution). An important part of our work includes involvement in field campaigns.

Chemistry/climate interactions

These interactions have become a major research topic in recent years. We have included a detailed chemistry package into the Met Office's climate model, to study composition change since the industrial revolution and into the future. We have calculated the change in surface ozone at the end of this century, under certain assumptions about changing industrial emissions. The change is very climate-dependent, but shows massive increases (which are expected to lead to major health problems) over some of the continents.

Atmospheric composition measurements

We have developed lightweight gas chromatography instruments to measure halocarbons. These have been deployed from balloons and high-flying research aircraft.

Many of the problems addressed are of an interdisciplinary nature. Members of the group, which numbers about 20 postdoctoral researchers and students, come from a wide range of backgrounds in mathematics and physical science. Within Cambridge we collaborate closely with scientists at the Department of Applied Mathematics and Theoretical Physics.