Meteorology Modulates the Impact of GCM Horizontal Resolution on Underestimation of Midlatitude Ocean Wind Speeds.

We utilize ocean 10‐m wind speed (U10m) from the microwave Multi‐sensor Advanced Climatology data set to examine the coupling between convective cloud and precipitation processes, synoptic state, and U10m and to evaluate the representation of U10m in global climate models (GCMs). We find that midlatitude U10m is underestimated by GCMs relative to observations. We examine two potential mechanisms to explain this model behavior: cold pool formation in cold air outbreaks (CAOs) associated with downdrafts that enhance U10m and sea surface temperature (SST) gradients affecting U10m through thermally forced surface winds at regional scales. When the effects of the CAO index (M) and SST gradients on U10m are accounted for, a relationship between GCM horizontal resolution and U10m appears. The strongest correlation between resolution and U10m is over the western boundary currents characterized by frequent CAOs atop strong SST gradients which drives the strongest surface fluxes on Earth. Plain Language Summary: Surface wind drives the exchange of momentum and energy between the atmosphere and ocean, forcing movement of ocean surface water that impacts the circulation responsible for transporting heat and carbon. It is thus important to study how well global climate models (GCMs) simulate near surface winds. Here, we show an underestimation of ocean surface wind in the latest‐generation of GCMs and examine how an underestimation of ocean surface winds covaries with biases in surface temperature and fine‐scale precipitation‐driven circulations. We show the effect of model horizontal grid resolution on the wind speed bias and analyze surface wind speed bias occurrence in western boundary currents. Key Points: Coupled model intercomparison project (CMIP6) models underestimate midlatitude ocean surface wind speed compared to spaceborne microwave radiometersSimulated ocean surface wind speed bias scales with model resolution at a magnitude strongly influenced by meteorologyOcean surface wind speed bias is most correlated with resolution in western boundary currents [ABSTRACT FROM AUTHOR]