Stability mechanisms and air temperature advection on the marine atmospheric boundary layer modulation at the southwestern Atlantic Ocean

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Abstract
Hydrostatic adjustment and vertical mixing are the two main mechanisms used to describe the stability of the marine atmospheric boundary layer (MABL) in oceanic regions with intense horizontal temperature gradients. To analyze the occurrence of these mechanisms, we performed simulations using an active coupled regional ocean–atmosphere numerical model in the southwestern Atlantic Ocean (SWA) region in October 2014 in the presence of an atmospheric frontal system. A novel in‐situ dataset was sampled by radiosondes in the Brazil–Malvinas Confluence (BMC) region and used with the model dataset. The vertical mixing mechanism and a prefrontal warm‐air temperature advection were identified, which modulated the shallower and more stable MABL. The hydrostatic adjustment mechanism was not evident because of the near‐surface wind convergence field modification caused by the large‐scale atmospheric system observed in our experiment. The coupled model simulation presented good agreement compared to in‐situ and satellite data. This contribution to the knowledge of the ocean–atmosphere interaction processes at the SWA reinforced that coupled models can be a helpful tool to investigate the air–sea interactions and physical mechanisms that explain MABL stability.

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