ICAS External Seminar - Malcolm Roberts (Met Office)

Global multi-centennial coupled climate modelling towards 10km resolution

Abstract: There is increasing evidence of the importance of improved representation of both the ocean mesoscale and corresponding scales in the atmosphere in global climate models, to better understand future climate hazard and uncertainty. To this end, EU EERIE involves four modelling groups producing centennial-multi-centennial coupled climate simulations with eddy-rich ocean models (grid spacing smaller than 10km), using simulation designs from either CMIP6 or CMIP6 HighResMIP. The work builds on the understanding gained from HighResMIP and from the EU PRIMAVERA project. For the Met Office model, new model components developed since CMIP6, such as a new atmosphere convection scheme CoMorph, have also been incorporated to improve aspects of large-scale model biases and smaller scale processes such as cyclone intensities.

The Met Office high resolution coupled model (20km-1/12˚) has now completed 200 years of a pre-industrial control simulation, and aspects of this will be compared to two lower resolution models which have already completed full CMIP6-style simulations to 2100. There are clear improvement at higher resolution in processes relating to air-sea coupling, some aspects of variability and climate extremes, as well as some important deficiencies such as the sea ice performance.

Such models are increasingly challenging our standard methods of data output, storage, sharing and analysis, particularly given their improved capabilities to represent high impact weather and hence the need for high frequency output. We are developing software tools to be run as a work flow with the model simulations, in order to automate analyses such as storm and eddy tracking and frontal diagnosis, with the potential to reduce the storage footprint while speeding up scientific insight.