Representation of the SPCZ-SACZ teleconnection and Rossby wave propagation in the Southern Hemisphere in two GCMs

SAURRAL, R.

Trieste

Conferencia; Conference on Teleconnections in the Atmosphere and Oceans; 2008

International Center for Theoretical Physics (ICTP)

General Circulation Models (GCMs) are currently the main tool to assess Climate Change projections for the upcoming decades. However, errors in the atmospheric circulation representation in these models increase projections’ uncertainties. The objective of the present study is to analyze the origin of the errors in precipitation over South America in two GCMs: ECHAM5_MPI-OM (Roeckner et al, 2003) and GFDL_CM2.0 (Delworth et al, 2006) by studying the differences in the atmospheric circulation of the Southern Hemisphere between the models and the reanalysis. Particular emphasis is put in the South Pacific Convergence Zone (SPCZ) - South Atlantic Convergence Zone (SACZ) tele-connection (Kalnay et al, 1986) and in the propagation of Rossby waves between the Indian Ocean and South America. OLR and upper-level wind fields are used as indicative of Rossby wave generators and propagators. Datasets include NCEP/NCAR reanalysis and ECHAM5 and GFDL2.0 outputs for the 1980-1999 period.