Verification of the linear ocean response to large scale wind forcing

Author(s)

Wandrey de Bortoli Watanabe

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2010-10-01

Examining board members

Paulo Simionatto Polito; Ricardo de Camargo; Ilson Carlos Almeida da Silveira

• Advisor: Paulo Simionatto Polito

Abstract

Rossby waves are the ocean response to perturbations whose temporal and spatial scales are significantly longer than both the inertial period and the Rossby radius of deformation. These perturbations are, more often than not, attributed to variations in the wind stress curl {\\em via} Ekman pumping. The waves cause isopycnal displacement which due to vertical advection may result in sea surface temperature (SST) anomalies. Depending on the ocean--atmosphere interaction, SST anomalies can either change the wind field or be changed by it due to the heat flux. This study makes use of ten years of satellite derived SST, wind vector, and sea surface height anomaly data to identify regions where there is direct wind forcing of linear Rossby waves. Cross-correlation maps between these variables show where linear interactions occur. A simple 1½ layer model forced by Ekman pumping was used to check if, in those regions, atmospheric variability alone can explain the observed Rossby wave variability as estimated from radar altimeter data. The interaction between SST and wind magnitude in the South Atlantic is distinct from all other ocean basins. SST and wind stress curl correlations show that the Ekman dynamics is not dominant in the Indian Ocean. In the tropical Atlantic and Pacific the model predictions are similar to the observations. Finally, evidence of genesis and feedback of planetary waves is presented for the eastern boundaries of the Atlantic and Pacific oceans. (AU)