South Pacific Convergence Zone (SPCZ) Variability and Biases in Models. Ben Lintner

Monday, October 27, 2014 - 2:00pm

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 empirical orthogonal function and composite analyses 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.


[1] Lintner, B.R., and J.D. Neelin, 2008: Eastern margin variability of the South Pacific Convergence Zone. Geophys. Res. Lett., 35, L16701, doi:10.1029/2008GL034298.

[2] Niznik, M.J., and B.R. Lintner, 2013:  Circulation, moisture, and precipitation relationships along the South Pacific Convergence Zone in reanalyses and CMIP5 models.  J. Clim., 26, 10174—10192, doi:10.1175/JCLI-D-13-00263.1.

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