Reconstructing the hydrometeorological indicators in the mountains of Southwestern Tuva and Northwestern Mongolia from dendrochronological data

Аннотация

We reconstructed the hydrometeorological parameters from dendrochronological data prior to the start of instrumental observations. As a result of the dendrochronological investigations made on the mountainous territories of Southwestern Tuva (Mongun-Taiga mountain massif) and Northwestern Mongolia (Mongolian Altai) during 2012–2014, we obtained two regional tree-ring chronologies for the upper and lower tree-lines. Results of dendroclimatic analysis suggest that the influence of the leading climatic factors for the growth of Siberian larch on the upper forest limit in Southwestern Tuva and Mongolian Altai accounts for 50% of the variability in growth. The chronology for the upper tree-line was used in reconstructing the June–July air temperatures, based on data from the Teeli meteorological station, starting in 1715. The analysis revealed the main climatic tendencies which are in good agreement with the climatic periods for the last 300 years: a general decrease in air temperature during the 19^th century (the end of the Neoglacial), and a subsequent rise by 2°C, on the average, i.e. there has been occurring is a positive trend of temperature rise since the late 19^th century. The chronology for the lower forest limits showed a statistically significant correlation with hydrological parameters. This chronology was used in reconstructing the water discharge, according to data from the Buyant-Deluun hydrological station, spanning the time interval since 1474. According to the reconstruction, in the latter half of the 14^th century, and in the 18^th and 19^th centuries the general humidification was lower than in the 20^th century. A positive trend toward an increase in humidity since the end of the 19th century is pointed out.