THE 1920S DROUGHT RECORDED BY TREE RINGS AND ...

420 ERYUAN LIANG ET AL.Figure 7. The reconstruction of (a) April–June precipitation based on two chronologies (HSE andHSW) in Region 2 (Shao and Wu, 1996), (b) May–July moisture indices based on the QYG chronologyin Region 3 (Zhang and Wu, 1997), (c) July–June precipitation based on the first principal componentof the seven chronologies (WL4, WL3, DLH1-DLH5) in Region 4 (Shao et al., 2005), (d) May–Junemoisture indices based on the ZHD and QML chronologies in Region 5 (Qin et al., 2004), (e) July–February precipitation based on the BEQ and XBY chronologies in Region 7 (Yuan et al., 2001)and (f) June–May precipitation based on the ZL, TU and TL chronologies in Yili of Region 7 (Yuanet al., 2000). Each reconstruction is based on the linear regression. The period from 1922 to 1932 isdelineated by two vertical lines.