Using Observations and a Low-order Dynamic Model to Study MJO Events

Dr. Justin Stachnik

Joint Institute for Regional Earth System Science & Engineering, University of California, Los Angeles, California, USA

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

Abstract

Intraseasonal variability of the tropical atmosphere is dominated by the Madden-Julian oscillation (MJO), an eastward propagating and planetary-scale mode, which has significant local and far-reaching dynamical effects on low-latitude weather and global climate. Despite its importance, current generations of global climate models (GCMs) struggle with simulating many of the observed features of the MJO. While recent work has largely focused on MJO initiation, fewer studies have examined the large-scale conditions associated with quiescent periods of the MJO and the decay of existing events. Understanding these mechanisms may provide a valuable context toward improving simulations of MJO initiation and propagation in GCMs and operational weather forecast models. This talk presents a climatology of MJO termination events in observations and the “skeleton model”, a low-order dynamical model specifically designed for studying tropical intraseasonal variability and the MJO. The precursor environmental conditions related to MJO termination are explored in observations and the skeleton model, along with the potential for improved predictability of termination events. Finally, lessons learned for obtaining more realistic simulations are discussed in addition to applications and future sensitivity tests of MJO physics using the skeleton model.

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