The Influences of Tropical Volcanic Eruptions with Different Magnitudes on Persistent Droughts over Eastern China

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.Atmosphere 2020, 11, 210 2 of 14 regional climate changes at different spatiotemporal scales and fundamentally affect the development of human communities, great efforts have been devoted to investigating the influences of volcanic eruptions on regional climate changes [2]. Many studies have confirmed that volcanic activities can produce global-scale cooling in the short term [3][4][5] and trigger a long-term cooling in the Arctic through the positive feedback of ice and snow cover [6]. The initiation of the Little Ice Age (LIA) was also found to be associated with volcanic eruptions and sustained due to the feedback between the sea ice and ocean [7].The impacts of volcanic eruptions on regional temperature and precipitation changes have attracted much attention recently [8]. Both reconstructed data and model simulations demonstrated that, on a global scale, volcanic eruptions can lead to rainfall deficit in summer monsoon regions over the world [9], with the largest precipitation decreases occurring in tropical areas [10]. On a regional scale, Northern Hemisphere volcanic eruptions are more likely to reduce Northern Hemispheric monsoon precipitation than equatorial and southern monsoon rainfall [11]. Large volcanic eruptions in the past millennium triggered anomalous dry conditions in Asia [12,13], but it was relatively wetter over the southeast part while drier in the central part [12]. In Europe, strong volcanic eruptions induced an aridity in the central part, while relative wetter conditions existed in the northern part [14]. Some studies also found that volcano-induced droughts usually persist longer over the ocean than ...

Comparisons on characteristics and mechanisms of the decadal megadroughts over eastern China between MCA and LIA

“…Then, large‐scale circulation and SST data were used to explore the mechanisms behind decadal megdroughts. Eastern China is defined as the area 25–40°N, 105–122°E to be consistent with previous studies (Ning et al, 2019a; 2019b; Chen et al, 2020a; 2020b; 2020c; Qin et al, 2020).…”

“…Stevenson et al (2018) also found that strong volcanic eruptions influence the megadroughts over different regions, through alterations in the structure of Atlantic multidecadal oscillation (AMO) and ENSO teleconnections. Chen et al (2020a); (2020b); (2020c) further concluded different magnitudes of volcanic eruptions have different influences on the megadroughts, such as the magnitudes and durations, through a group of sensitivity experiments. In addition, Sun et al (2017) found the drought of 1,420–1,516 have been influenced not only by frequent volcanic eruptions, but also persistently low solar radiation.…”

“…The decadal megadroughts in the history had significant societal and economic consequences, which influenced the historical evolutions (Cook et al, 2010, 2015a; 2015b; Zheng et al, 2014). In addition, the risks of decadal megadroughts along with other extreme events are likely to increase in the future, because of the global temperature increases (Ning & Qian, 2009; Ning and Bradley, 2015; Ning et al, 2015; Cook et al, 2015a; 2015b; Ault et al, 2016; Chen et al, 2020a; 2020b; 2020c). Therefore, improved understanding on mechanisms of decadal megadroughts is critical to the future predictions of decadal megadroughts and also the sustainable societal and economic developments.…”

“…Besides the internal variability of climate system, the influences from external forcings were also widely examined through analyses of observed data and model simulations (Peng et al, 2014; Ning et al, 2018, 2019a, 2020; Chen et al, 2020a; 2020b; Yue et al, 2020; Zheng et al, 2016), such as greenhouse gases concentrations, volcanic eruptions, and solar radiation, and so on. Ning et al (2019a) found that the models can only reproduce the comparable magnitudes and durations of megadroughts to the reconstructions with external forcings For the influences from greenhouse gases concentrations, recent warming due to the increased greenhouse gas concentrations may contribute to the drying, therefore, megadroughts have increased substantially since the 1970s in many regions, including East and South Asia (Dai et al, 2011).…”

One Drought and One Volcanic Eruption Influenced the History of China: The Late Ming Dynasty Mega‐drought

“…Hokkaido-Komagatake (9.6 Tg) and several other volcanoes (8.4 Tg). Given that volcanic eruptions smaller than 25 Tg have little intensifying impact on droughts in eastern China (Chen et al, 2020), and the timing of Mt. Hokkaido-Komagatake eruption (July 1640) is very close to that of Mt.…”