Effects of the PDO Phase on the Tropical Belt Width

• DOI: 10.1175/jcli-d-11-00244.1
• Publication Date: 2011-12-09T14:21:16Z
• Authors: Barbara Grassi; Gianluca Redaelli; Pablo Osvaldo Can...; Guido Visconti
• Keywords: Forcing (mathematics); Atmospheric models

Recent studies have shown that the tropical belt (TB) has progressively expanded since at least late 1970s. This trend been largely attributed to radiative forcing due greenhouse gas (GHG) increase and stratospheric ozone depletion, even if an influence of sea surface temperature (SST) anomalies also suggested. The impact Pacific decadal oscillation (PDO) on TB width is investigated in this work. study performed by using both Atmospheric Model Intercomparison Project (AMIP) idealized simulations, produced NCAR Community Atmosphere Model, version 3 (CAM3) GCM reanalysis data [40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40), ERA-Interim, Modern-Era Retrospective Analysis Research Applications (MERRA)]. Reanalyses show a switch PDO from positive negative phase can lead significant expansion during equinoxes. effect, indicating possible contribution widening characterized last decades, not correctly reproduced model simulations. Deficiencies sensitivity model-simulated convective processes SST are suggested as cause underestimation.