Seasonal-to-interannual modulations of tropical instability waves and their coupling with the atmosphere

Recent satellite observations have revealed that tropical instability waves (TIWs) are characterized by strong coupling between the atmosphere and ocean in the tropical eastern Pacifi. The mechanisms that produce this ocean-atmosphere coupling are not fully understood. Observations also show that TIW activities are strongly modulated by the seasonal cycle and interannual variations of the tropical eastern Pacific. TIW signals are strongest from July through December and are more energetic during La Nina years than El Nino years. It is possible that at different locations of the tropical Pacific or different seasons or years, a different mechanism is responsible for the ocean-atmosphere coupling. This study uses long-term coupled atmosphere-ocean GCM simulations to discuss the three-dimensional structures of TIW in the atmosphere and ocean and to study TIW's ocean-atmosphere coupling mechanisms on different timescales and at various locations of the Tropical Pacific.