Air–sea coupling in the North Atlantic during summer
In this work, we have investigated the evolution of the summer air–sea interaction in the North Atlantic Ocean and the physical processes involved using reanalysis data and model simulation. It is found that an atmosphere disturbance over the North Atlantic Ocean in the preceding winter favors the build-up of a North Atlantic horseshoe-like sea surface temperature anomaly (SSTA) pattern in the summer through modifying the northeast trade winds and changing ocean upwelling and downwelling. The changed ocean condition (SSTA, upwelling, and downwelling) further intensifies the atmosphere disturbance as a positive feedback. The thermal advection of the atmosphere disturbance weakens the SSTA pattern in the following autumn and winter. The anomalous circulation associated with the air–sea interaction in the observations is characterized by a barotropic structure in the middle and high latitudes of the North Atlantic Ocean. The baroclinic component is enhanced in the model simulation, particularly in the seasons from summer to winter. The life cycle of the air–sea interaction is about 1 year in both the observations and simulations.
The authors thank D. Straus, E. Manzini, and two anonymous reviewers for their suggestions and comments to significantly improve the manuscript. We are grateful for the advice and support of J. Shukla and L. Bengtsson. We also like to thank P. Schopf for his help to develop the coupled model. This work was supported by NOAA CLIVAR Atlantic Program (NA169PI570 and NA04OAR4310115).
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