Impact of Volcanic Aerosols on the Hydrology of the Asian Monsoon and Westerlies‐Dominated Subregions: Comparison of Proxy and Multimodel Ensemble Means

Abstract

Proxy-model comparisons show large discrepancies in the impact of volcanic aerosols on the hydrology of the Asian monsoon region (AMR). This was mostly imputed to uncertainties arising from the use of a single model in previous studies. Here we compare two groups of CMIP5 multimodel ensemble mean (MMEM) with the tree-ring-based reconstruction Monsoon Asia Drought Atlas (MADA PDSI), to examine their reliability in reproducing the hydrological effects of the volcanic eruptions in 1300-1850 CE. Time series plots indicate that the MADA PDSI and the MMEMs agree on the significant drying effect of volcanic perturbation over the monsoon-dominated subregion, while disparities exist over the westerlies-dominated subregion. Comparisons of the spatial patterns suggest that the MADA PDSI and the MMEMs show better agreement 1 year after the volcanic eruption than in the eruption year and in subregions where more tree-ring chronologies are available. The MADA PDSI and the CMIP5 MMEMs agree on the drying effect of volcanic eruptions in western-East Asia, South Asian summer monsoon, and northern East Asian summer monsoon (EASM) regions. Model results suggest significant wetting effect in southern EASM and western-South Asia, which agrees with the observed hydrological response to the 1991 Mount Pinatubo eruption. Analysis on model output from the Last Millennium Ensemble project shows similar hydrological responses. These results suggest that the CMIP5 MMEM is able to reproduce the impact of volcanic eruptions on the hydrology of the southern AMR.

Potential Influences of Volcanic Eruptions on Future Global Land Monsoon Precipitation Changes

“…The monsoon circulations over the South American, South African, and Australian monsoon regions exhibit anticyclonic anomalies in the aftermath of large volcanic eruptions, which lead to significant decrease of monsoonal precipitation in their warm seasons. These results are comparable to the drying effects of past eruptions in the regional monsoons, mainly through the monsoon circulation weakening resulting from reduced land-sea thermal contrast (Colose et al, 2016;Cui et al, 2014;Dogar & Sato, 2019;Dogar et al, 2017;Gao et al, 2018;Man et al, 2014;Wegmann et al, 2014;Zambri et al, 2017;Zhuo et al, 2020). The increased precipitation over the North American monsoon region is possibly due to precipitation decrease of the Intertropical Covergence Zone (ITCZ) and an anticyclone anomaly over the Eurasian-African continental area after the strong volcanic forcing, which lead to anomalous ascending motion and enhanced North American monsoon rainfall (Figures S5 and S6).…”

Volcanic effects on climate: recent advances and future avenues

“…For many of the climate impacts listed above, the exact response such as the timing, magnitude or spatial heterogeneity often differs not only between climate model studies, but also between model-simulated and observed or reconstructed responses (e.g. Driscoll et al 2012;Pauling et al 2021;Wilson et al 2016;Zanchettin et al 2016;Zhuo et al 2020;Zuo et al 2021). Aerosol-climate modelling studies have also demonstrated large discrepancies in the simulated aerosol size and dispersion following past large eruptions such as the 1815 eruption of Mt.…”

How Volcanic Aerosols Globally Inhibit Precipitation

“…This framework could prove useful for future evaluations of volcanic precipitation response. Furthermore, while we focused our evaluation on the global response to volcanic aerosols, the regional precipitation response to volcanism remains poorly studied outside of a few monsoon regions (Liu et al, 2016;Zhuo et al, 2020). It also remains to be seen how the mechanisms driving post-eruption precipitation reduction vary with eruption magnitude.…”