Session: Cross-cutting Group 2 (Paleovar, Past to future, Data assimilation)
Author: Binod Dawadi / email@example.com / Tribhuvan University, Kathmandu Nepal
Co-author: Eryuan Liang, Institute of Tibetan Plateau Research, Chinese, Academy of Sciences;
Based on Himalayan birch collected from the Sagarmtha National park and Langtang National park of central Nepal, we developed 460-year chronology, currently this is the longest chronology of this species from High Asia. Himalayan birch showed strong and direct relationship with spring (March-May) precipitation thus, used to reconstruct spring precipitation back to 1552AD. This is the first precipitation reconstruction using this species. The reconstruction captured 37% of the variance in the calibration model over the period 1960-2009. Reconstruction (2011-1552) shows annual, multiannual to decadal variation. The year 1999, 1813 and 1954 respectively experienced the driest spring where as 1775, 1557 and 1988. The reconstructed series showed AD1811- 1821 and 1995-2005 are the driest decades where as AD 1926-1936 and 1640-1650 the wettest in the whole reconstruction (1552-2011). The most interesting feature of this reconstruction is a decrease in precipitation between 1 to 5 years following the eruption of volcanic eruption depending upon the strength of the volcano. The MTM spectral analysis showed significant spectral peaks at 3.4, 3.6, 3.9, 26.2, 30, 42.7, 53.8 years. The reconstructed precipitation also showed significant correlation with the Kathmandu precipitation and other larger-scale regional indices used to represent the South Asian monsoon rainfall. Thus, the result here indicates a great potential to extend the tree-ring series in length using Himalayan birch that could provide high-resolution palaeoclimatic records that span the last several centuries and fill the gaps from the data scare region of central Himalaya.