A new study published in Nature Climate Change used idealized coupled model experiments to show that increased cross-equatorial winds in the eastern Pacific during the past decades strengthened the cold tongue (south of the equator). This in turn reduced ENSO amplitude and promoted more central Pacific (CP) – type El Nino events.
Here is Nature Climate Change news and views article about Hu and Fedorov (2018):
https://www.nature.com/articles/s41558-018-0261-3