Abstract
In this study, the influences on persistent droughts over Eastern China from tropical volcanic eruptions with three categories of magnitudes, i.e., 25 Tg, 50 Tg, and 100 Tg, were investigated through three groups of volcanic sensitivity experiments based on the Community Earth System Model (CESM). The results showed that, the 25 Tg tropical volcanic eruptions are too weak to significantly influence the regional precipitation changes over Eastern China, while the 50 Tg tropical volcanic eruptions can strongly intensify droughts and prolong the drought conditions for about five years. Both the extension and intensification of the drought conditions induced by 100 Tg tropical volcanic eruption are the largest among the three sensitivity experiments. These drought conditions are mainly caused by the weakened East Asia Summer Monsoon (EASM), and their extension and intensification depend on the strength of the volcanic eruptions. The intensities of weakened EASMs after volcanic eruptions are associated with the distinct ocean–land thermal contrast after eruptions. The ocean–land thermal contrast is the largest after the 100 Tg tropical volcanic eruptions, while it is much weaker after the 25 Tg volcanic eruptions. The durations of drought extensions are determined by the recovery rates of the West Pacific Subtropical High (WPSH), which are associated with the magnitudes of the volcanic eruptions.
Highlights
Volcanic eruption is a major external forcing that affects different aspects of regional climate changes over the world by injecting plenty of sulfate volcanic aerosol into the stratosphere and reducing the solar radiation arriving at the surface [1]
The results showed that precipitation changes following the 25 Tg volcanic eruptions were significantly smaller than those after 50 Tg eruptions
The findings demonstrate that the effects of volcanic eruptions with11,magnitudes of 25 Tg, 50 Tg, and 100 Tg are significantly different, with more severe
Summary
Volcanic eruption is a major external forcing that affects different aspects of regional climate changes over the world by injecting plenty of sulfate volcanic aerosol into the stratosphere and reducing the solar radiation arriving at the surface [1]. Some studies found that many drought events in the world are triggered primarily by internal variability of climate system [17,18,19] External forcings such as strong volcanic eruptions can cast significant effects on the droughts over the Eastern China [2]. Previous studies demonstrated that the linear combination of volcanic forcing and drought events triggered by internal variability over Eastern China may intensify and extend the drought conditions for about 3–4 years, and the duration and intensity of droughts depend on the volcanic eruptions occurring at different drought phases [34]. Do the volcanic eruptions with different magnitudes have different influences on the droughts over Eastern China triggered by internal variability? This study will help to provide insights to the better understanding of the combined effects of internal variability and external forcing, and improve future projections of climate changes and corresponding adaptations
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