CLIVAR-PAGES-WCRP summer school on El Niño

Axel Timmermann

doi:10.22498/pages.17.1.40

Abstract

the role of equatorial waves in the ENSO recharge mechanism. In carrying out these research projects students applied the concepts taught during the lectures, such as the recharge oscillator paradigm, ENSO frequency entrainment, equatorial waves, basin modes, teleconnection patterns and multiplicative noise. Understanding ENSO's past requires an in-depth understanding of the coupled instability mechanisms that underlie ENSO and the annual cycle in the eastern equatorial Pacific. Oversimplified concepts, such as the dynamical thermostat, can mislead paleo-proxy interpretations, and a thorough heat-budget analysis of corresponding model simulations is usually needed to understand ENSO changes that occurred with past climate forcings, such as orbitally induced variations in solar insolation. Numerous coupled general circulation model studies have demonstrated that for certain ENSO regimes a weaker (stronger) annual cycle corresponds to stronger (weaker) ENSO variability. Testing these model-derived relations with paleo-proxy data, such as corals, lake records, speleothems, mollusks, and tree rings, would be an important contribution towards a better understanding of ENSO forcing mechanisms in the past.

Highlights

Workshop Reports the French Commissariat à l’Energie Atomique, the French Institut National des Sciences de l’Univers, the European Geosciences Union, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, and the Belgian private company “Vincotte”
Sixteen graduate students in oceanography, meteorology and geology from 10 countries gathered to learn from lecturers on a broad range of ENSO-related topics: ENSO theory (Fei-Fei Jin, University of Hawai’i, USA), ENSO phenomenology (Michael McPhaden, NOAA, USA), ENSO predictability (Magdalena Balmaseda, European Centre for Medium-range Weather Forecasts, UK; Richard Kleeman, Courant Institute, USA), and ENSO’s sensitivity to past and future climate change (Scott Power, Centre for Australian Weather and Climate Research Bureau of Meteorology/CSIRO, Australia; Axel Timmermann, University of Hawai'i, USA)
Energized by fresh goat milk kefir, exotic local fruit smoothies and island-style cuisine, the students conducted research projects in addition to the 3-4 hour daily lecture-marathon. They studied the effects of ENSO on the Antarctic Peninsula, the rapid termination of the 2008 La Niña event that was induced by easterly wind bursts, the geographical reaches of a tropical megadrought ~4.2 kyr ago, the effects of state-dependent noise on the predictability of ENSO, the dynamics of warm pool El Niño events, the effects of Atlantic multi-decadal SST variability on ENSO, and the role of equatorial waves in the ENSO recharge mechanism

Summary

Introduction

Workshop Reports the French Commissariat à l’Energie Atomique, the French Institut National des Sciences de l’Univers, the European Geosciences Union, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, and the Belgian private company “Vincotte”. Axel Timmermann International Pacific Research Center, University of Hawaii, Honolulu; axel@hawaii.edu The summer school “ENSO Dynamics and Predictability”took place in the lush jungle of Puna on the Big Island of Hawai’i.

Results

Conclusion