Two Types of ENSO Varying in Tandem Facilitated by Nonlinear Atmospheric Convection
July 23,2020

Tao Geng Wenju Cai Lixin Wu

Published in Geophysical Research Letter July 2020

The El Niño‐Southern Oscillation (ENSO) has two distinct regimes, one in the eastern Pacific (EP) featuring strong El Niño and the other in the central Pacific (CP) characterized by strong La Niña. Establishment of atmospheric convection in the climatologically cold and dry EP region provides a major source of the nonlinearity, but its role in the relationship between CP‐ and EP‐ENSO variability and their long‐term change remain unclear. By constructing a nonlinear two‐box recharge‐oscillator model, here we show that nonlinear atmospheric convection operates to boost strong EP El Niño, strong CP La Niña, and evolution in tandem of variability and skewness of CP‐ and EP‐ENSO. Further, the observed coherent long‐term increase in frequency of strong EP El Niño, strong CP La Niña, and variability of the two‐type ENSO over the past decades is facilitated by a corresponding increase in the nonlinear atmospheric convection.

Geng, T., Cai, W., & Wu, L. (2020). Two types of ENSO varying in tandem facilitated by nonlinear atmospheric convection. Geophysical Research Letters, 47, e2020GL088784.

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