Dr Keith Williams

Areas of expertise

  • Model Evaluation

  • Seamless modelling approach

  • Understanding cloud processes

  • Process-orientated metrics of model performance

Publications by Keith Williams

Current activities

Keith heads the Atmospheric Processes and Parametrizations group. The group is responsible for the representation of physical processes in our weather and climate models. This includes how we represent the atmospheric boundary layer, clouds and microphysics, radiative transfer in the atmosphere, moist atmospheric convection, orographic processes and surface processes, together with very high resolution model development.

Keith's personal research is in process-orientated model evaluation across timescales, in particular evaluating cloud processes. A variety of diagnostic techniques (initial tendencies, nudging, sensitivity experiments, etc.) are employed to help identify the source of any errors. Detailed comparison of the model against active and passive satellite data (using satellite simulators in the model to emulate the characteristics of the space-borne instruments), combined with surface-based cloud observations have been used for cloud evaluation.

Career background

Keith obtained his degree in physics and meteorology, and his PhD, from the University of Reading. Upon joining the Met Office in 1998, Keith focused on understanding processes leading to a spread in climate sensitivity between climate models. Most of this work involved understanding differences in the cloud response to climate change between models, and determining confidence in their response through evaluation of relevant processes in the current climate. 

In 2008, Keith became the manager of the Seamless Model Assessment team which began the work of drawing together model assessment techniques from the weather and climate communities. Following a re-structuring of the Met Office science areas in 2010 to promote more seamless working, Keith began leading the newly formed Model Evaluation team, which performs process-orientated evaluation of the global Unified Model and works with parametrization developers to improve systematic errors.

In 2017, Keith became head of the Atmospheric Processes and Parametrizations group.

External recognition

  • Co-chair of the World Meteorological Organization's Working Group on Numerical Experimentation (WGNE). This group has the responsibility of fostering the development of atmospheric circulation models for use in weather, climate, water and environmental prediction on all time scales and diagnosing and resolving shortcomings in these models.
  • Chair of the WGNE-WGCM Transpose-AMIP project. This project aims to run climate models in 'weather forecast mode', by initialising them with re-analyses and running five-day hindcasts. This methodology allows the models to be evaluated against detailed observations such as at ARM sites, CloudSat passes, etc. for particular synoptic events.
  • Member of the WGNE-WGCM Diagnostics and Metrics Panel. The panel acts as a focal point for the development of tools, metrics and diagnostic techniques for model evaluation.