Abstract
The frequency of extreme drought events in northeastern China (NEC) has increased since the 2000s, and such a decadal anomalous trend may lead to significant stress on agriculture and economic development. The correlation between Arctic sea ice loss in spring and extreme summer droughts over NEC was investigated. The results show that the loss of sea ice over the Barents Sea in spring is associated with extreme droughts and positive height anomalies over NEC in summer. The physical processes include two pathways. First, sea ice loss from the Barents Sea to the Kara Sea results in reducing baroclinicity over the ice loss region but increasing baroclinicity over the ice melting region, which is favorable to the wave ridge over northern Europe and negative-phase Summer North Atlantic Oscillation (SNAO). One wave train originates from negative-phase SNAO over North Atlantic–Europe and spreads to central Europe, central Asia, and NEC. Second, another wave motion flux originates from the Barents–Kara Sea propagating eastward, and then disperses southward to NEC. Both wave trains lead to anomalous anticyclonic circulation and westward subtropical high, which favors descending motion and less water vapor flux, thereby contributing to extreme drought.
Highlights
Drought is characterized by below-normal precipitation, which has become an increasing concern in recent years
Motivated by extreme droughts over northeast China, which have exhibited a decadal increase since the mid-1990s, this study explored its association with Arctic sea ice loss, as this sea ice has significantly decreased beyond the decadal timescale
The results show the enhanced impact of spring SIC over the Barents Sea on subsequent extreme summer droughts over northeastern China (NEC) after 1998, and a possible mechanism was suggested
Summary
Drought is characterized by below-normal precipitation, which has become an increasing concern in recent years. Since the 1980s, the frequency of severe droughts over northeastern China (NEC) and the duration of droughts have been increasing (Liang et al 2011; Yu et al 2014; Zhang et al 2013). These characteristics have expanded southward from the semiarid boundary of northern China in recent decades, and the grassland region of NEC has been decreasing at 2.8% per year (Ma and Fu 2006). The frequency and duration of extreme drought in NEC are increasing (Wang et al 2016; Zhang et al 2009). As NEC is an important economic region in northern China, the drought variation and causes of extreme drought should be studied
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