Work package 6:Dynamical and Physical Coupling of the Tropical Troposphere and Stratosphere (lead by S. Watanabe)

This study employs atmospheric general circulation models (AGCMs) with good representations of the variability of the tropical stratosphere to study the dynamical coupling processes of the tropical troposphere and stratosphere. In collaboration with the SPARC QBOi project, we will perform a series of ensemble seasonal hindcast simulations starting twice a year (1 May and 1 November), in which the AGCM is initialized with reanalysis data and prescribed SST and run for 9 months. The ensemble hindcast simulations (1993-2007) include several ENSO events and QBO cycles, suitable to study their relationships. The vertical coupling of tropical troposphere and stratosphere through generation, propagation and dissipation of atmospheric waves, and the predictability of QBO will be investigated using the hindcast dataset.