Statistics of stochastic entropy for recorded transitions between ENSO states

TL;DR

This paper investigates the entropy changes during ENSO phase transitions using stochastic statistical physics, revealing most transitions are not extreme entropic events, with one near-extreme case identified.

Contribution

It applies stochastic statistical physics to analyze ENSO transition entropy, providing new insights into climate phase change dynamics.

Findings

Most ENSO transitions show moderate entropy variation.

The 1999-2000 La Niña to 2002-2003 El Niño transition is near an extreme entropy event.

The study verifies fluctuation relations in ENSO phase transitions.

Abstract

We analyse the transitions between established phases of the El Ni\~no Southern Oscillation (ENSO) by surveying the daily data of the Southern Oscillation Index from an entropic viewpoint using the framework of stochastic Statistical Physics. We evaluate the variation of entropy produced due to each recorded path of that index during each transition as well as taking only into consideration the beginning and the end of the change between phases and verified both integral fluctuation relations. The statistical results show that these entropy variations have not been extreme entropic events; only the transition between the strong $1999-2000$ La Ni\~na to the moderate $2002-2003$ El Ni\~no is at the edge of being so. With that, the present work opens a long and winding avenue of research over the application of stochastic Statistical Physics to Climate Dynamics.