Routes to long-term atmospheric predictability in reduced-order coupled ocean-atmosphere systems

Prof. Stéphane Vannitsem
Royal Meteorological Institute of Belgium

10:00, 11 July, 2019
3#1118

Abstract
The long-term predictability in two different versions of the Modular Arbitrary Order Ocean- Atmosphere Model (MAOOAM) developed at the Royal Meteorological Institute of Belgium, is explored with emphasis on the role of the surface friction on the development of low-frequency variability within the atmosphere. Both versions differ by the specific geometry chosen for the ocean (closed or open boundaries in the zonal direction). Two routes to long-term predictability within the atmosphere are found with different phase space characteristics: (i) a chaotic wandering around an unstable periodic orbit in the case of the closed ocean basin, or a succession of erratic excursions closed to an unstable periodic orbit in the case of the open ocean basin. The implications of these different behaviors and their relations with the actual coupled ocean-atmosphere dynamics will be discussed.