The Role Of The Atmospheric And Oceanic Circulation In The Interaction Between The Tropics And Extra-Tropics

The climate of the tropical and extra-tropical regions are closely linked through atmospheric and oceanic teleconnection signals. Therefore, changes in the climate in the tropics have a significant impact on the extra-tropical climate, and vice versa. The teleconnection signals occur on time scales ranging from months to decades, and are thus of great importance for a series of climate variability and global warming issues. To examine the interaction between the tropics and extra-tropics, sea surface temperature (SST) anomaly experiments are performed with the Bergen Climate Model(BCM) through the so called"partial coupling"methodology. In this way, dedicated model sensitivity experiments have been carried out to elucidate the interaction between the tropics and extra-tropics. Particular focus is paid to the role of atmospheric and oceanic circulation anomalies in the interaction between the two regions. The main findings are as follow:1. The impact of the extra-tropical SST anomalies strongly influences the tropical climate. Positive extra-tropical SST anomalies, through signals carried through the atmosphere, increase the tropical SST; while the role of the ocean in the process is relatively weak. Furthermore, the effect on the extra-tropical SST by a tropical SST anomaly is small.2. For the near-equilibrium response to an extra-tropical SST anomaly, the changes of the meridional and zonal atmospheric circulation are...