Possible increase of tropical cyclone genesis frequency over the Northwest Pacific induced by the Tambora eruption in 1815

The impact of tropical volcanic eruptions (TVEs) on tropical cyclone (TC) activity remains a subject of ongoing debate. Here, we investigate the effects of the 1815 Tambora eruption, which occurred during the pre-industrial period, with that of the 1991 Pinatubo eruption in present-day era on TC activity in the western North Pacific (WNP). Using high-resolution simulations and proxy data derived from reanalyses, we find that both TVEs lead to significant increases in TC genesis frequency (TCGF) and track density (TCTD) over the WNP. The Tambora eruption triggers the equatorial central Pacific warming, inducing tropical westerly wind anomalies in the WNP. While thermodynamic conditions were generally unfavorable for TC genesis, the dominant influence of dynamic factors facilitated increased TC activity. Our findings suggest that the cooling effect of TVEs can be viewed as a transient analog of global warming, providing valuable insights into future TC variability under changing climatic conditions. • We find that the Tambora eruption in 1815 could induce an increase of TCGF over the WNP, consistent with the Pinatubo impact in 1991. • Thermodynamic and dynamic factors oppose in WNP TCGF changes during Tambora eruption, with dynamics dominating. • The Tambora eruption caused equatorial central Pacific warming, weakening Walker Circulation, thus increasing WNP TCGF.