Abstract
To investigate the pure long-term influence of single mega volcanic eruption (SMVE) of universal significance on Arctic temperature changes in summer and winter, the Samalas eruption in Indonesia which is the largest eruption over the past millennium is selected as an ideal eruption for simulation study based on Community Earth System Model. The significant Arctic cooling lasts for 16 years after the Samalas eruption. The obvious Arctic cooling shifts from summer to winter, and this seasonal change of cooling after the SMVE only exists in the high-latitude Arctic region. The cooling range in Arctic summer is larger than that in winter during the first 2 years, due to the strong weakening effect of volcanic aerosol on summer incident solar radiation and the snow-ice positive feedback caused by the rapid expansion of summer sea ice, while the winter sea ice in the same period doesn’t increase obviously. Starting from the third year, the Arctic winter cooling is more intense and lasting than summer cooling. The direct weakening effect of aerosol on solar radiation, which is the main heat source in Arctic summer, is greatly weakened during this period, making summer cooling difficult to sustain. However, as the main heat source in Arctic winter, the sea surface upward longwave radiation, sensible heat, and latent heat transport still maintain a large decrease. Furthermore, sea ice expansion and albedo increase result in the decrease in solar radiation and heat absorbed and stored by the ocean in summer. And the isolation effect of sea ice expansion on air-sea heat transfer in winter during this period makes the heat transfer from the ocean to the atmosphere correspondingly reduce in winter, thus intensifying the Arctic winter cooling. Additionally, the Arctic Oscillation (AO) changes from the negative phase to the positive phase in summer after the SMVE (such as Samalas), while it is reversed in winter. This phase change of AO is also one of the reasons for the seasonal changes in Arctic cooling.
Highlights
Global warming is more and more severe with the increase of greenhouse gases after the Industrial Revolution
This suggests that the impact of the Samalas mega volcanic eruption on Arctic temperature change is more dramatic and that there is a strong signal of seasonal variations in Arctic cooling
Our simulations facilitate the direct comparison of the impacts of the single mega tropical eruption on Arctic summer and winter temperature changes by performing a systematic comparison of the radiative and dynamical effects of single mega volcanic eruption (SMVE)
Summary
Some scholars pointed out that after eliminating the direct radiation forcing caused by explosive volcanic activity, four consecutive volcanic eruptions in the 13th century led to a significant expansion of sea ice in the NH, especially in March (Zhong et al, 2010) These studies suggest that the changes in Arctic temperature and sea ice in the winter respond strongly to the large volcanic eruption. A recent modeling study showed that it would take nearly two decades for the global and hemispheric cooling caused by the Samalas mega eruption to disappear completely if other external forcings and new volcanic disturbances were excluded (Liu et al, 2020b).
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