loading page

Triple-Dip La Niña in 2020-22: Impact of Annual Cycle in Tropical Pacific SST
  • +2
  • Song Jiang,
  • Congwen Zhu,
  • Zeng-Zhen Hu,
  • Ning Jiang,
  • Fei Zheng
Song Jiang
Chinese Academy of Meteorological Sciences
Author Profile
Congwen Zhu
State Key Laboratory of Severe Weather, and Institute of Climate System,Chinese Academy of Meteorological Sciences

Corresponding Author:[email protected]

Author Profile
Zeng-Zhen Hu
Climate Prediction Center
Author Profile
Ning Jiang
State Key Laboratory of Severe Weather, and Institute of Climate System,Chinese Academy of Meteorological Sciences
Author Profile
Fei Zheng
Institute of Atmospheric Physics, Chinese Academy of Sciences
Author Profile

Abstract

The triple-dip La Niña in 2020-22 is characterized by persisting easterly and southeasterly wind anomalies over the tropical central and southeastern Pacific. Our results show that the wind anomalies are associated with two leading modes of the annual cycle (antisymmetric and symmetric modes) of sea surface temperature (SST). The first two modes account for 82.2% and 13.5% of total variances, linking to the seasonal swing of SST distribution in the northern and southern hemispheres and the temporal evolution of El Niño-Southern Oscillation (ENSO), respectively. The persistent negative phase of the symmetric mode enhances easterly wind, while the antisymmetric mode strengthens the southeasterly wind. The negative phase of the antisymmetric mode is regulated by the contrast of SST anomalies between the northern and southern hemispheres. Therefore, both the zonal and the meridional process associated with annual cycle anomalies may play an important role in the evolution of the triple-dip La Niña in 2020-22.
22 Feb 2023Submitted to ESS Open Archive
27 Feb 2023Published in ESS Open Archive