Abstract

Air-sea heat and moisture exchanges are a conduit through which the atmosphere exchanges energy with the ocean, the main climatic energy store. A summary review of relevant resolution-related process-deficiencies in coupled climate models is presented. Eddies in particular are known to modulate surface fluxes by impacting on the boundary layer depth and surface winds. New observational heat flux estimates identify regions of high inter-annual air-sea flux variability in northern boundary currents and other ocean eddying regions, in addition to the equatorial Pacific. Outside the Equatorial Pacific, inter-annual variability in TOA fluxes is much smaller than the surface variability. Heat exchanged at the surface must therefore be distributed or supplied by ocean and atmosphere, i.e. these high flux regions appear to represent time-varying pumps of heat between the ocean and atmosphere. We analyse inter-annual variability in air-sea exchanges in a series of consistent 1, 1/4 and 1/12o NEMO ocean only and coupled NEMO -UM climate simulations, including a new coupled N512 -1/12o model, developed under CHARISMA project. The representation of both time-mean surface fluxes and their inter-annual variability in the boundary currents and eddying regions appear to improve considerably as the ocean resolution is increased in both coupled and ocean-only runs. Finally, we discuss the potential implications of these findings to the low resolution IPCC CMIP coupled model predictions and to NAO predictability in GloSea5.