The ENSO effect in both northern and southern winter stratosphere has been recognized to be significant. While the northern stratospheric polar jet is mainly weakened or strengthened by ENSO, the southern stratospheric polar jet mainly exhibits a meridional shift during ENSO, both of which can be attributed to the ENSO-related anomalous planetary waves in the extratropical troposphere and their upward propagation into the stratosphere. 

However, the ENSO forcing is not only from the tropical Eastern Pacific (TPO), but also from the tropical Indian Ocean (TIO) and Atlantic (TAO), and the contributions from each of the ocean basins have not been clarified yet. 

Recent studies by Dr. RAO Jian from Nanjing University of Information Science & Technology and his PhD supervisor Prof. REN Rongcai at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics at the Institute of Atmospheric Physics, Chinese Academy of Sciences indicate significant destructive interference of the TIO with the TPO during ENSO, in their forcing in both the northern (Fig. a) and southern winter stratosphere, which has resulted in the considerably weaker ENSO effect than it should be when forced only by the TPO ENSO; This destructive interference is mainly due to the mostly out-of-phase wave patterns forced by TIO with those forced by TPO, in the extratropical troposphere. In contrast, the TAO shows little interference with TPO in stratosphere during ENSO winter, because the TAO effect exhibits a three-stage evolution from early to late winter and to the following spring during ENSO (Fig. b). 

The findings concerning the mutual interference between different tropical ocean basins during ENSO have been published in Climate Dynamics.

References:

1 Rao, Jian and Rongcai Ren*, 2020: Modeling study of the destructive interference between the tropical Indian Ocean and eastern Pacific in their forcing in the southern winter extratropical stratosphere during ENSO, Climate Dynamics, 54: 2249-2266， https://doi.org/10.1007/s00382-019-05111-6

2 Rao，J  and  Rongcai Ren*, 2018：Varying  stratospheric  responses  to  tropical  Atlantic  SST  forcing from early to late winter, Climate Dynamics,  51: 2079–2096,  DOI: 10.1007/s00382-017-3998-x
Link: https://doi.org/10.1007/s00382-017-3998-x

3 Rao J. and R.-C. Ren*, 2016: A decomposition of ENSO’s impacts on the northern winter stratosphere: competing effect of SST forcing in the tropical Indian Ocean, Climate Dynamics, 46: 3689–3707. DOI: 10.1007/s00382-015-2797-5.
Link: https://doi.org/10.1007/s00382-015-2797-5

Contact: REN Rongcai, rrc@lasg.iap.ac.cn