A tree‐ring‐based drought index reconstruction for far‐western Mongolia: 1565–2004

Abstract

AbstractTree‐ring records can provide longer, high‐resolution records of climate variability in remote regions such as western Mongolia, where recorded data are extremely limited. Here, we use three absolutely dated tree‐ring‐width chronologies to reconstruct the Palmer Drought Severity Index (PDSI) for a grid point in western Mongolia (48.75°N, 88.75°W). A reconstruction of the June–September PDSI for this region extends from 1565 to 2003 and explains 41% of the total variance in the instrumental PDSI. The 439‐year reconstruction shows that starting in the 20th Century and continuing into the 21st Century there is a large‐scale regional increase in growing‐season moisture conditions compared to the prior centuries, a trend not seen in central or eastern Mongolian tree‐ring reconstructions. This increasing trend in western Mongolia is consistent with station observations and other nearby proxy records. The wettest 5‐year period of the reconstruction is 1741–1745 followed by 1993–1997, and the driest period is 1755–1759, followed by 1882–1886. Spectral analysis shows significant periodicities at approximately 22, 11, 7 and 5 years. The reconstruction shows similar trends to a PDSI reconstruction from NW China during the 20th Century and also correlates with lake‐level data from nearby Khar‐Us Nuur, Mongolia. Copyright © 2008 Royal Meteorological Society