Reconstruction of May–July precipitation in the north Helan Mountain, Inner Mongolia since A.D. 1726 from tree-ring late-wood widths
Reconstruction of May—July precipitation in the north Helan Mountain, Inner Mongolia since A.D. 1726 from tree-ring late-wood widths

By analyzing statistical characteristics of five tree-ring standard chronologies, early-wood ring width (EWW), late-wood ring width (LWW), total ring width (TRW), minimum early-wood density (MinD), maximum late-wood density (MaxD) and, their climatic response re-spectively, we reconstructed the May to July precipitation using late-wood ring width (LWW) over the north Helan Mountain since A.D. 1726. The explained variance is 42% (R2adj = 41%, F = 31.46, p < 0.000001). After 11-a moving average, the explained variance reaches 82% (F = 156.9, p < 0.05). On the decadal scale, the rainfall reconstruction of the northern Helan Mountain displays a quite similar variation pattern with that of the April to early July precipitation in Baiyinaobao, east of Inner Mongolia for the last 150 years. It may reflect the intensity variation of the East Asia Summer Monsoon front to a certain extent. Spectrum analysis shows 11-a and 22-a periodicities in the May to July precipitation reconstruction at the north Helan Mountain.