The Hectometric Modelling Challenge: Gaps in the current state of the art and ways forward towards the implementation of urban-scale weather and climate models

Abstract: Current state of the art NWP and regional climate models run at km scale or “convection permitting” resolutions. For a number of years now a number of centres have been experimenting with higher resolutions with gridlengths of the order 100m (sometimes referred to as “hectometric” or “Urban-scale” models). It has been shown that higher resolution models give benefits for a variety of meteorological phenomena which would translate into improved forecasts.  Examples include convection, fog and urban effects. In this paper, which is based on a workshop held in Dec 2022, we discuss the challenges which still need to be overcome to make the transition from promising research into useful forecast systems. We summarise the outcomes from the workshop.  As well as over arching issues such as the cost of the models we discuss dynamical cores and physics dynamics coupling, parameterisation issues (including surface), sources of surface data, observations requirements, data assimilation, predictability and postprocessing. 

Biography: Humphrey has a BSc in Physics from the University of Bristol and  PhD in low temperature physics (superconductivity) from the University of Cambridge, Cavendish Laboratory. In his early career he worked in Cambridge on high temperature superconductivity and on the plasma fusion programme at Culham Laboratory. Since joining the Met Office Humphrey has worked on high resolution models, leading a project to develop km scale models during the 2000’s. He now leads the Met Office project to develop Urban-scale models. His main scientific interests are in the areas of convection, urban meteorology and orographic rain. He was a PI on the WesCon/WOEST campaign and the follow on ParaChute project.