A138-05
Impact of Model Resolution on Tropical Cyclone Simulation of Present-day and Future Projection using the HighResMIP Multi-model Ensemble
Friday, 11 December 2020: 20:46
Virtual
Malcolm J Roberts1, Joanne Camp2, Jon Seddon3, Pier Luigi Vidale4, Kevin Hodges5, Benoit Vanniere6, Jennifer Mecking7, Rein Haarsma8, Alessio Bellucci9, Enrico Scoccimarro10, Louis-Philippe Caron11, Fabrice Chauvin12, Laurent Terray13, Marie-Pierre Moine14, Dian Putrasahan15, Christopher Roberts16, Retish Senan17, Colin M. Zarzycki18, Paul Aaron Ullrich19, Yohei Yamada20, Ryo Mizuta21, Chihiro Kodama22, Dan Fu23, Qiuying Zhang24, Gokhan Danabasoglu25, Nan A Rosenbloom26, Hong Wang27 and Lixin Wu27, (1)Met Office Hadley Centre, Exeter, United Kingdom, (2)UK Met Office, Exeter, United Kingdom, (3)Met Office Hadley center for Climate Change, Exeter, United Kingdom, (4)University of Reading, Department of Meteorology and National Centre for Atmospheric Science (NCAS), Reading, United Kingdom, (5)University of Reading, Reading, United Kingdom, (6)University of Reading, Reading, RG6, United Kingdom, (7)University of Southampton, Southampton, United Kingdom, (8)Royal Netherlands Meteorological Institute, De Bilt, Netherlands, (9)Euro-Mediterranean Center on Climate Change, Climate Simulations and Predictions Division, Bologna, Italy, (10)INGV National Institute of Geophysics and Volcanology, Forli, Italy, (11)Institut Català de Ciències del Clima, Barcelona, Spain, (12)Météo-France, CNRM/GMGEC/AMACS, Toulouse, France, (13)CERFACS, Toulouse, France, (14)CERFACS European Centre for Research and Advanced Training in Scientific Computation, Toulouse Cedex 01, France, (15)Max Planck Institute for Meteorology, The Ocean in the Earth System, Hamburg, Germany, (16)ECMWF, Reading, United Kingdom, (17)European Center for Medium-Range Weather Forecasts, Reading, United Kingdom, (18)National Center for Atmospheric Research, Climate and Global Dynamics Laboratory, Boulder, CO, United States, (19)University of California Davis, Land, Air & Water Resources, Davis, CA, United States, (20)JAMSTEC, Kanagawa, Japan, (21)Meteorological Research Institute, Tsukuba, Japan, (22)JAMSTEC, Yokohama, Japan, (23)Texas A&M University, Oceanography, College Station, United States, (24)Texas A&M University, College Station, United States, (25)National Center for Atmospheric Research, Boulder, CO, United States, (26)NCAR/CGD, Boulder, CO, United States, (27)Ocean University of China, Qingdao, China
Abstract:
A multi-model, multi-resolution set of simulations over the period 1950-2050 using a common forcing protocol from CMIP6 HighResMIP have been completed by nine modelling groups. Analysis of tropical cyclone performance using two different tracking algorithms (TRACK and TempestExtremes) suggests that enhanced resolution towards 25 km typically leads to more frequent and stronger tropical cyclones, together with improvements in spatial distribution and storm structure. Both of these factors reduce typical GCM biases seen at lower resolution.
Using single ensemble members of each model, there is little evidence of systematic improvement in interannual variability in either storm frequency or Accumulated Cyclone Energy compared to observations when resolution is increased. Changes in the relationships between large-scale drivers of climate variability and tropical cyclone variability in the Atlantic are also not robust to model resolution.
However using a larger ensemble of simulations (of up to 14 members) with one model at different resolutions does show evidence of increased skill at higher resolution. The ensemble mean correlation of Atlantic interannual tropical cyclone variability increases from ~0.5 to ~0.65 when resolution increases from 250 km to 100 km. In the North West Pacific the skill keeps increasing with 50 km resolution to 0.7. These calculations also suggest that more than six members are required to adequately distinguish the impact of resolution within the forced signal from the weather noise.
Projected tropical cyclone activity by 2050 generally declines in the Southern Hemisphere, while changes in other ocean basins are more uncertain and sensitive to both tracking algorithm and imposed forcings. Coupled models with smaller biases suggest very small changes in average TC 10m wind speeds by 2050.
