Meridional Heat Transport During Atmospheric Rivers in High-Resolution CESM Climate Projections

Meridional sensible and latent heat transport is evaluated for regions with landfalling atmospheric rivers using both MERRA-2 reanalysis and fully coupled CESM1.3 high-resolution climate projections. Western North America, the United Kingdom, and the Iberian Peninsula are chosen to represent the regions significantly impacted by atmospheric rivers (ARs). CESM1.3 historical simulations can accurately represent both sensible and latent regional meridional heat transports compared to MERRA-2 both for the total period analyzed (1980–2016) and for days with atmospheric rivers only. Uncertainty in these calculations due to AR identification is assessed by applying available Tier 1 AR-catalogs from Atmospheric Tracking Method Intercomparison Project (ARTMIP) to the MERRA-2 analysis. CESM1.3 climate projections suggest that under global warming, latent heat transport increases across all regions in the mid-latitudes where sensible heat decreases (increases) for western North America (Europe). Generally, changes to the meridional heat transport are forced by the upper-level meridional wind component.