SoMAS / ITPA - South Pacific Convergence Zone (SPCZ) Variability and Biases in Models

Benjamin Lintner from the Department of Environmental Sciences at Rutgers University speaks to SoMAS on Wednesday, February 12, 2014.

TOPIC: "South Pacific Convergence Zone (SPCZ) Variability and Biases in Models"


Abstract:
The South Pacific Convergence Zone (SPCZ) is a key deep convective feature of Pacific basin climate, especially in austral summer when it extends from the tropical western Pacific warm pool to Southern Hemisphere (SH) midlatitudes halfway across the Pacific basin. In the context of climate simulation, a wide range of simulated SPCZ behaviors is evident in current generation models, e.g., coupled general circulation models often produce an excessively zonal climatological SPCZ. In this talk, the variability and biases in the SPCZ as simulated in the suite of Coupled Model Intercomparison Project Phase 5 (CMIP5) models are described. In particular, diagnostics developed from approaches such as composites, empirical orthogonal function analysis and k-means clustering are used to evaluate CMIP5-simulated SPCZ-region relationships among large-scale circulation, moisture vertical structure, and precipitation across multiple timescales and to compare to available observations. Results of ongoing research involving simulations with an intermediate level complexity model, the two-level Quasi-equilibrium Tropical Circulation Model (QTCM2), are also presented. These simulations serve to highlight some of the key processes impacting the SPCZ.