Winter warming (WW) over northern Eurasia has been observed and modeled following major tropical volcanic eruptions, although recent studies suggest such a volcanic response may be overwhelmed by internal variability. Here we show for the first time that a high latitude volcanic eruption can also produce WW, using the 1783 Icelandic Laki eruption as an example. Its persistent stratospheric volcanic cloud from summer to early winter and the associated warming of the mid-latitude stratosphere play a pivotal role in triggering WW. We conduct climate model simulations with updated volcanic forcing of this Laki eruption, and the results match two recently available temperature reconstructions, while model results of various eruptions without substantial cold-season aerosol loadings do not produce WW. The abnormal mid-latitude stratospheric warming enhances the meridional temperature gradient, strengthens the polar vortex, and alters both the horizontal and vertical energy redistribution that contributes to WW. The findings help to reconcile the model-observation discrepancy of post-eruption winter climate responses, and point to the critical role of stratosphere-troposphere coupling in producing a radiative perturbation that produces this circulation response.

Northern Eurasia winter warming;,Laki volcanic eruption;,cold season aerosol,stratosphere-troposphere coupling