Moisture dipole over the Tibetan Plateau during the past five and a half centuries

Abstract

The South Asian Monsoon and mid-latitude Westerlies are two important controls on Tibetan Plateau (TP) fresh water resources. Understanding their interaction requires long-term information on spatial patterns in moisture variability on the TP. Here we develop a network of 23 moisture-sensitive tree-ring chronologies from major juniper forests in a north-south transect on the eastern TP. Over the past five and a half centuries, we find that these chronologies cluster into two groups, North and South, of ∼33° N. Southern and northern regional chronology subsets are positively and significantly correlated with May-June Palmer Drought Severity Indices (PDSI). The meridional moisture stress gradient reconstructed from these data suggests substantial stochastic variation, yet persistent moisture stress differences are observed between 1463-1502 CE and 1693-1734 CE. Identification of these patterns provides clues linking them with forced or intrinsic tropical-extratropical interactions and thus facilitates studies of interannual-decadal dipole variations in hydroclimate over the TP.