Hub-Height Wind Bias Off the Coast of Northern California Due to the Misrepresentation of Marine Stratocumulus Clouds in HRRR

Stratocumulus clouds, with their low cloud base and top, are known to affect the atmospheric boundary layer (ABL) wind and turbulence profile, which then influences wind energy resources. GOES satellite data reveals an abundance of stratocumulus clouds in late spring and summer months off the coast of Northern California where there are active plans to deploy floating offshore wind farms at two lease areas (near Morro Bay and Humboldt). We find that NOAA’s High Resolution Rapid Refresh (HRRR) numerical model consistently misrepresents marine stratocumulus cloud properties (cloud fractions, top heights, etc.) in these locations. At both the Humboldt Bay and Morro Bay locations, we find the stratocumulus clouds simulated by HRRR tend to have lower cloud tops by about 500 m and weaker diurnal cycles compared to the cloud top observations and spatial structures seen by GOES satellite. Sources of error between Doppler lidar-equipped buoy observations at wind turbine relevant heights (i.e., from surface to 300 m above sea level) and HRRR simulated wind speeds under different cloud conditions at both offshore California locations are explored. Through this analysis, we shall investigate possible correlations between the wind-speed errors from HRRR (with respect to lidar-buoys) as a function of errors in cloud properties from HRRR (with respect to GOES satellite retrievals). The findings from this study will potentially inform how to improve the modeling of wind resources off the coast of Northern California.