Large-scale controls on the ITCZ: hemispheric albedo, energy transports and teleconnections — Australian Meteorological and Oceanographic Society

Large-scale controls on the ITCZ: hemispheric albedo, energy transports and teleconnections (#2051)

Matthew Hawcroft 1 , Mat Collins 2 , Jim Haywood 2
  1. USQ/Met Office, Exeter, DEVON, United Kingdom
  2. CEMPS, University of Exeter, Exeter, Devon, UK

The link between cross-equatorial energy transport, the double-intertropical convergence zone (DI) problem and biases in tropical and extratropical albedo and energy budgets in climate models have been investigated in multiple studies, though DI biases persist in many models. Here, an outline of recent results focussing on experiments using a coupled climate model, HadGEM2-ES, are presented. These results show the sensitivity of the mean position of tropical precipitation to energy perturbations in low and high latitudes. The tropical precipitation response is modulated by the coupled energy transport response to these perturbations. The impact on the tropical climate of high and low latitude forcing strongly contrasts, with large changes in tropical precipitation and modulation of the DI bias when the tropics are cooled as precipitation moves away from the cooled hemisphere. These responses are muted when the extratropics are cooled, as the meridional energy transport anomalies that are excited by these energy budget anomalies are partitioned between the atmosphere and ocean. This behaviour has implications for understanding both model mean state biases and as a tool to investigate the plausibility of differing large scale circulation responses to a warming climate as simulated by current climate models. Further analysis using a multi-model study will be shown, highlighting the contrasting sensitivity of different models to equivalent energy perturbations.

 

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