Deepashree Dutta: Role of volcanic eruptions in tropical precipitation variability
Volcanic eruptions inject sulphur aerosols into the stratosphere, thereby reducing incoming solar radiation and may induce annual-to-multidecadal climate variability. They are generally associated with reduced global mean precipitation, while regional responses are more complex due to changes in large-scale circulation. Using observations and coupled model simulations, Hua et al. (2018) showed that anthropogenic and volcanic aerosols drive contrasting precipitation responses between the Sahel and the Amazon during boreal summer over 1950-2017. Similarly, Lechleitner et al. (2017) identified interhemispheric precipitation changes in proxy records over the last 2000 years, linked to shifts in the Intertropical Convergence Zone and influenced by both solar and volcanic forcing. Here, using Last Millennium Coupled Model Intercomparison Project Phase 6 simulations from multiple models (including ACCESS-ESM1.5), we investigate whether volcanic eruptions between 850 and 1850 induce a bipolar precipitation response between the Sahel and the Amazon. Following volcanic eruptions, our results show an increase in precipitation over the Amazon while precipitation decreases over the Sahel. We further examine the underlying physical mechanisms and the influence of eruption latitude on the strength of this seesaw signal.
Hua, W., Dai, A., Zhou, L., Qin, M., & Chen, H. (2019). An externally forced decadal rainfall seesaw pattern over the Sahel and southeast Amazon. Geophysical Research Letters, 46, 923–932. https://doi.org/10.1029/2018GL081406
Lechleitner, F., Breitenbach, S., Rehfeld, K. et al. Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw. Sci Rep 7, 45809 (2017). Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw | Scientific Reports