Intraseasonal Dynamics of Equatorial Atmosphere and Oceans

Nels Nelson Award Ceremony and Distinguished Lecture:

Distinguished Lecturer: Harindra Fernando, Professor, Dept of Civil & Environmental Engineering & Earth Sciences, Department of Aerospace and Mechanical Engineering, University of Notre Dame

Climate modeling intercomparison studies demonstrate a clear divergence of future climate predictions for equatorial regions, calling for better understanding of atmospheric and oceanic processes of tropics.  Current efforts of ‘seamless’ modeling from weather to climate scales require a deeper understanding of dominant processes at various scales, from meso to climate scales (e.g., synoptic, seasonal, decadal) as well as transitional phenomena in between. To this end, intraseasonal disturbances of tropical atmosphere and oceans that occupy time scales form about 10 to 60 days have gained recent attention because of its perceived relation to Boreal summer monsoons and rainfall.  Of particular importance are the migration of the Intertropical Convergence Zone, equatorial planetary waves that propagate in all directions within atmosphere and oceans, interaction of these waves with landmass (e.g. maritime continent) and ocean boundaries, and air-sea interactions associated with such disturbances. During 2012-2015, a field experimental program was conducted in the northern Indian Ocean under the sponsorship of the Office of Naval Research to study intraseasonal oscillations in tropics. These were dubbed ASIRI (Air Sea Interactions in the Northern Indian Ocean) and ASIRI-RAWI (Remote Sensing of Atmospheric Waves and Instabilities). An array of observing platforms were used, covering multiple countries and several ocean basins. Observations and associated modeling conducted during these programs will be described in this presentation, paying particular attention to intriguing phenomena that were observed and explained using analyses of fluid dynamics.