Processes that Contribute to Future South Asian Monsoon Differences in E3SMv2 and CESM2
Connections between South Asian monsoon precipitation and El Niño/Southern Oscillation (ENSO) in a future warmer climate are investigated in the E3SMv2 and CESM2 in terms of future simulated tropical SSTs and ENSO amplitude and how the processes involved affect those connections.
For the first time, we attribute the stronger future monsoon-ENSO connections in E3SMv2 compared to CESM2 to two specific processes involving the pattern of SST warming in the tropical Pacific and future ENSO amplitude. Gaining insight into these processes will contribute to understanding and predicting the South Asian monsoon and ENSO in the future on seasonal to decadal timescales.
We attribute the future strengthening of monsoon-ENSO connection in E3SMv2 compared to CESM2 to two processes:
- Larger future El Niño-like SST response in CESM2 shifts the anomalous Walker Circulation eastward and weakens the monsoon-ENSO connection in CESM2 compared to E3SMv2,
- Larger amplitude increase in future ENSO in E3SMv2 strengthens the monsoon-ENSO connection compared to CESM2
This two-model analysis provides unique and crucial insights into the processes that affect the predictability of the economically impactful South Asian monsoon.