Regional Ocean-Atmosphere Feedback in Eastern Pacific

Hyodae Seo, Art Miller, and John Roads
Scripps Institution of Oceanography

Using a high-resolution ocean-atmosphere coupled model, recent observational evidence for air-sea interactions in the eastern Pacific is reproduced. Model data are subsequently analyzed to examine various hypotheses for the regional-scale coupling processes.
As a specific focus, undulations of SST by Tropical Instability Waves (TIWs) and vertical shear adjustment of the atmospheric boundary layer (BL) in eastern tropical Pacific are studied. It is shown that undulating SST fronts force an unambiguous response in the atmospheric BL throughout its whole height. Furthermore, it is seen that there are significant changes of wind curl and divergence fields around the SST fronts implying that perturbed surface wind-derivative fields may lead to an additional feedback to the ocean. In addition to this dynamic feedback, there seems to be significant thermodynamic feedback due to changes in air-sea temperature difference and winds across the SST front. Similar coupling patterns are also seen in the midlatitude ocean near the California coast on much smaller spatial and temporal scales. This implies that this regional-scale coupling is ubiquitous over the world ocean wherever strong SST fronts are associated with mesoscale oceanic meanders, eddies, and filaments.