Will Increasing Climate Model Resolution Be Beneficial for ENSO Simulation?

• Published in: Geophysical research letters 2022-06, Vol.49 (11), p.n/a
• Main Authors: Liu, Bowen, Gan, Bolan, Cai, Wenju, Wu, Lixin, Geng, Tao, Wang, Hong, Wang, Shengpeng, Jing, Zhao, Jia, Fan
• Format: Article
• Language: English
• Subjects: Asymmetry; Atmospheric models; Climate; Climate models; Climatology; Cyclones; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; ENSO; Feedback; Heat flux; Heat transfer; Heat transport; high‐resolution climate model; Hurricanes; Modelling; Ocean models; Precipitation; Resolution; Sea surface; Sea surface temperature; Simulation; Southern Oscillation; Surface temperature; Tropical climate; Tropical cyclones
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL096932

Increasing climate model resolution offers multifaceted benefits, such as improving modeled tropical cyclones. However, the extent to which it benefits El Niño‐Southern Oscillation (ENSO) simulation remains unknown. Here, comprehensive information on the sensitivity of ENSO performance to various resolutions is provided, based on a multi‐model and multi‐resolution ensemble of global coupled models. Overall, the reduced model biases of the equatorial sea surface temperature (SST) and precipitation mean state in higher‐resolution models may be attributed to increased oceanic resolution, and thus, better resolved eddy‐driven heat transport. ENSO spatial patterns were reproduced clearer in the eddy‐present models, likely due to the improved mean state and associated surface thermodynamic feedback. However, increasing atmospheric resolution alone deteriorates ENSO asymmetry, which may be due to the degradation of nonlinear atmospheric feedback. It remains challenging to alleviate the SST−shortwave‐flux feedback bias, which is a major source of too‐weak net heat flux feedback, irrespective of model resolution. Plain Language Summary The impact of model resolution on simulated weather and climate phenomena has received much attention in recent studies. In this study, we used seven global coupled models, at horizontal grid spacings ranging from 250 to 10 km, to assess El Niño‐Southern Oscillation (ENSO) performance in historical simulations from 1950 to 2014. Several metrics regarding the tropical Pacific mean states, ENSO characteristics, feedback processes, and teleconnections were evaluated. We found that in higher resolution models, the model biases of sea surface temperature and precipitation climatology in the equatorial Pacific had reduced, which may be because of the increased resolution of oceanic components. Such improvements would appear to be beneficial for a better representation of the ENSO spatial structure. However, solely refining the atmospheric resolution of climate models substantially degrades the reproduction of ENSO asymmetry and could conflict with the improvements made by the high‐resolution oceanic component. A comprehensive assessment of impacts from various resolutions offers a useful perspective for future model development. Key Points Higher oceanic resolution improves eddy‐induced heat transport, equatorial Pacific sea surface temperature (SST) and precipitation mean state Eddy‐present models improve El Niño‐Southern Oscillation (ENS