Climate Dynamics

, Volume 38, Issue 9, pp 1757-1773

First online:

Twentieth century Walker Circulation change: data analysis and model experiments

  • Qingjia MengAffiliated withLeibniz-Institut für MeereswissenschaftenRiver and Coastal Environment Research Center, Chinese Research Academy of Environmental SciencesKey Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences
  • , Mojib LatifAffiliated withLeibniz-Institut für Meereswissenschaften Email author 
  • , Wonsun ParkAffiliated withLeibniz-Institut für Meereswissenschaften
  • , Noel S. KeenlysideAffiliated withLeibniz-Institut für Meereswissenschaften
  • , Vladimir A. SemenovAffiliated withLeibniz-Institut für MeereswissenschaftenA. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences
  • , Thomas MartinAffiliated withLeibniz-Institut für Meereswissenschaften

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


Recent studies indicate a weakening of the Walker Circulation during the twentieth century. Here, we present evidence from an atmospheric general circulation model (AGCM) forced by the history of observed sea surface temperature (SST) that the Walker Circulation may have intensified rather than weakened. Observed Equatorial Indo-Pacific Sector SST since 1870 exhibited a zonally asymmetric evolution: While the eastern part of the Equatorial Pacific showed only a weak warming, or even cooling in one SST dataset, the western part and the Equatorial Indian Ocean exhibited a rather strong warming. This has resulted in an increase of the SST gradient between the Maritime Continent and the eastern part of the Equatorial Pacific, one driving force of the Walker Circulation. The ensemble experiments with the AGCM, with and without time-varying external forcing, suggest that the enhancement of the SST gradient drove an anomalous atmospheric circulation, with an enhancement of both Walker and Hadley Circulation. Anomalously strong precipitation is simulated over the Indian Ocean and anomalously weak precipitation over the western Pacific, with corresponding changes in the surface wind pattern. Some sensitivity to the forcing SST, however, is noticed. The analysis of twentieth century integrations with global climate models driven with observed radiative forcing obtained from the Coupled Model Intercomparison Project (CMIP) database support the link between the SST gradient and Walker Circulation strength. Furthermore, control integrations with the CMIP models indicate the existence of strong internal variability on centennial timescales. The results suggest that a radiatively forced signal in the Walker Circulation during the twentieth century may have been too weak to be detectable.


Tropical atmospheric circulation Twentieth century Walker Circulation