EGU22-6852
https://doi.org/10.5194/egusphere-egu22-6852
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Local meridional circulation changes contribute to a projected slowdown of the Indian Ocean Walker circulation

Sahil Sharma1,2, Kyung Ja Ha1,2,3, Wenju Cai4, Eui-Seok Chung5, and Tamás Bódai1,6
Sahil Sharma et al.
  • 1Center for Climate Physics, Institute of Basic Science, Busan, South Korea
  • 2Department of Climate System, Pusan National University, Busan, South Korea
  • 3BK21 School of Earth and Environmental Systems, Pusan National University, Busan, South Korea
  • 4Center for Southern Hemisphere Oceans Research (CSHOR), CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
  • 5Division of Atmospheric Sciences, Korea Polar Research Institute, Incheon, South Korea
  • 6Pusan National University, Busan, South Korea

The weakening of zonal atmospheric circulation, a widely accepted projection of climate change in response to global warming, features a weakening of the Indian Ocean Walker circulation (IWC), with an anomalous ascending motion over the western and anomalous descending motion over the eastern Indian Ocean.  The projected IWC weakening has previously been attributed to slower warming in the east than the west, that is, to a positive Indian Ocean Dipole (IOD)-like warming pattern.  However, such a warming pattern can also be induced by IWC weakening. As a result, the cause-and-effect relationship cannot be easily determined, and the projected change is poorly constrained and highly uncertain. Here, using a suite of coupled climate model simulations under a high-emission scenario, we find that the IWC slowdown is accompanied by not only a positive IOD-like warming pattern but also anomalous meridional circulation that is associated with anomalous descending motion over the eastern Indian Ocean. We further show that the anomalous local meridional circulation is closely linked to enhanced land-sea thermal contrast and is unlikely to result from the positive IOD-like warming pattern, suggesting that the IWC weakening is in part driven by the anomalous local meridional circulation. Our findings underscore the important role of local meridional circulation changes in modulating future IWC changes. 

How to cite: Sharma, S., Ha, K. J., Cai, W., Chung, E.-S., and Bódai, T.: Local meridional circulation changes contribute to a projected slowdown of the Indian Ocean Walker circulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6852, https://doi.org/10.5194/egusphere-egu22-6852, 2022.

Comments on the display material

to access the discussion