Anomalous Energy Fluxes and Feedback Parameter Over the Course of ENSO Events

Abstract

Internal variability may provide constraints on the global temperature response to forcing. Previous work showed that ENSO induces atmospheric stratification anomalies that lead to tropical low cloud anomalies not correlated with mean temperature. Here, we expand this argument. We discuss the physical processes leading to a canonical evolution of the global feedback parameter over the course of an ENSO event, , where is the ENSO phase, and differs from the feedback parameter observed in typical forcing experiments. During the growth phase of El Niño, the heat flux from the tropical Pacific into the atmosphere is amplified by a net gain at the top of the atmosphere (an apparent runaway state), and heat is primarily redistributed among tropical ocean basins. During the peak phase, the static stability anomaly rapidly decays, and only in the decay phase does the climate system lose heat to space.