The multi-taper method (MTM) spectra of the drought area index (DAI) of the (a) central Asia and the (b) monsoonal Asia, as well as the wavelet spectra of the DAI of the (c) central Asia and the (d) monsoonal Asia.

<p>The multi-taper method (MTM) spectra of the drought area index (DAI) of the (a) central Asia and the (b) monsoonal Asia, as well as the wavelet spectra of the DAI of the (c) central Asia and the (d) monsoonal Asia.</p

Location of the PDSI grids and the central and eastern Asia is delimited according to Chen et al. (2010).

<p>Location of the PDSI grids and the central and eastern Asia is delimited according to Chen et al. (2010).</p

The cross wavelet transform (XWT) between PDO and DAI of (a) central and (b) monsoonal Asia, and the squared wavelet coherence (WTC) between PDO and DAI of (c) central and (d) monsoonal Asia.

<p>The significance level (<i>p</i><0.05) is indicated by thick contours. The left arrows indicate anti-phase relationship, and right arrows indicate in-phase relationship between PDO and DAI.</p

The drought area index (DAI) and the (red bold line) low-passed (lower than the cutoff frequency of 0.02) DAI for (a) central and (b) monsoonal Asia.

<p>The yellow shaded area indicates the in-phase decadal variations and the green shaded area indicates the anti-phase decadal variations between them.</p

Correlations between the reconstructed PDO series and the reconstructed PDSI for the periods (a) 1300–1450s, (b) 1460s–1550s, (c) 1560s–1640s, (d) 1650s–1710s, (e) 1720s–1850s and (f) 1860s–1996.

<p>Correlations between the reconstructed PDO series and the reconstructed PDSI for the periods (a) 1300–1450s, (b) 1460s–1550s, (c) 1560s–1640s, (d) 1650s–1710s, (e) 1720s–1850s and (f) 1860s–1996.</p