Now fully retired from the Met Office, Andy continues to collaborate on an ad hoc basis with a number of Scientists in Foundation Research
Areas of expertise:
Consistent approximation of the governing dynamical equations.
Hydrodynamic instability theory and numerical model testing.
Trajectory construction in semi-Lagrangian numerical models.
Quasi-geostrophic theory and other 'balanced' models of atmospheric flow.
General meteorological dynamics and thermodynamics.
Over time, Andy's main area of research has been the consistent formulation of approximate models of atmospheric flow and thermodynamics. The resulting models may incorporate only geometric approximations and form the basis for numerical weather prediction and climate simulation codes. They may involve more profound approximations and be designed to increase conceptual insight into atmospheric flow systems - especially those responsible for day-to-day weather changes.
The governing equations on which the dynamical core of the UM is based incorporate fewer approximations than those used by other centres. Current work involves the formulation of governing equations without the remaining assumption that the geopotentials of apparent gravity may be represented as spheres.
The ENDGame formulation allows the shallow atmosphere and/or hydrostatic approximations to be switched on and off. Current work is focused on the dynamically consistent specification of these approximations in gravity environments that are not spherically symmetric.
The semi-Lagrangian scheme used in the UM and in ENDGame involves the construction of trajectory segments for every grid point at every time step. A significant proportion of Andy's work deals with the development and appraisal of trajectory construction schemes.
A further area of activity is the search for stable flows for use in numerical model testing. This has been successfully concluded for the shallow water equations by exploiting published stability criteria. Baroclinic flows are at present being investigated.
Andy worked in the Dynamics Research group from until his retirement in 2011. From 1996 he managed the Met Office's Theory Applications group at JCMM, having previously (from 1990) been Deputy Principal at the Met Office College, with responsibility for graduate training.
In earlier jobs within the Met Office, Andy managed the Numerical Techniques group of the Short Range Forecast division (1990-91) and the Diagnostics and Predictability group of the Synoptic Climatology branch (1987-1990). Andy joined the Met Office in 1978 as a Research Fellow, working with Professor Raymond Hide in the Geophysical Fluid Dynamics Laboratory. He contributed to budget studies of the atmosphere's vector angular momentum and to combined numerical, theoretical and experimental projects on rotating fluid systems (to 1987). Certain steady flows in the laboratory systems prompted an interest in the occurrence of locally-steady flows in the atmosphere, and led to the development of a steady-state versus time-dependent view of atmospheric flow that found expression in the later Diagnostics and Predictability work.
Before joining the Met Office, Andy took a PhD and carried out post-doctoral studies at Imperial College, London. He worked on simplified climate models with Dr John Green (to address in particular the apparently non-Newtonian processes that maintain the climatological mean surface winds against friction). In even earlier times Andy graduated in Natural Sciences, having specialised in theoretical physics.