Meteorological drought and its large-scale climate patterns in each season in Central Asia from 1901 to 2015

The long-term variations in meteorological drought and its large-scale climate patterns in each season in Central Asia from 1901 to 2015 remain unclear. Here, this issue is addressed using meteorology measurements and reanalysis data through correlation and composite analyses. The drought intensity index (DII) and extent index (DEI) do not exhibit significant linear trends from 1901 to 2015 but do exhibit interannual to interdecadal variations. Both the DII and DEI are highly correlated with the tropical Nino 4 sea surface temperature (SST) and extratropical atmospheric teleconnections, including the East Atlantic (EA) pattern, the East Atlantic/West Russia (EAWR) pattern, and the Arctic oscillation (AO), but with seasonal discrepancies in terms of the degree of influence. The winter drought is strongly linked to both the negative EA and negative EAWR patterns, while spring and autumn drought are strongly linked to the negative EAWR and negative EA patterns, respectively. In the winter, spring, and autumn, drought is also closely linked to below normal Nino 4 SST. The links to EA and EAWR patterns are mainly derived from their impacts on precipitation in the central and northern sectors, while the link to Nino 4 SST is mainly derived from its impacts on precipitation in the southern sector. By considering both drought intensity and drought extent, the ten extreme drought years for each season are selected and, through composite analysis, their large-scale climate patterns are studied. The extreme drought generally occurs in the contexts of a negative EA pattern in winter, a negative EAWR pattern in spring, and a negative AO pattern in autumn. As an exception, summer drought is weakly correlated with Nino 4 SST and is not correlated with extratropical atmospheric teleconnections.

Automated summary

The study shows that drought in Central Asia is influenced by different factors in different seasons, with winter drought mainly driven by negative EA and negative EAWR patterns, while spring and autumn drought are primarily affected by negative EAWR and negative EA patterns, respectively. Extreme drought years tend to occur within the context of specific climate patterns for each season.