Reconstructed summer Palmer Drought Severity Index since 1850 AD based on δ13C of larch tree rings in eastern Siberia

We present a tree-ring reconstruction of Palmer Drought Severity Index (PDSI) in Ust-Maya region (60 degrees 00'N, 133 degrees 49'E), central part of eastern Siberia using total ring (TR) widths and latewood (LW) delta C-13 chronologies from larch trees (1850-2008 AD). Summer (JJA) PDSI was correlated positively and negatively with the TR widths and LW delta C-13, respectively. Using a multiple liner regression approach, we reconstructed summer PDSI using the time series of TR widths and LW delta C-13. The reconstruction showed an interannual to decadal wet/dry fluctuation with several moist periods before 1950s and a severe drought event from 1991 to 1993. Comparison of the reconstruction with reconstructed July PDSI for the Yakutsk region, 300 km northwest of Ust-Maya, showed heterogeneous changes in the mean states of soil moisture, but synchronous year-to-year changes. These results indicate that regional studies are quite important to precisely depict the spatio-temporal variability of hydrological changes in the central part of eastern Siberia. (C) 2015 Elsevier B.V. All rights reserved.