Degree of connectivity in reconstructed precipitation dynamics and extremes for semiarid regions across South Siberia

Tree rings from forest-steppes of temperate continental Asia are useful proxies for the moisture regime reconstructions, encompassing environmental variations such as warming climate, changing frequency and intensity of droughts. Heterogeneity of precipitation leaves open the question of the probability of spatially large-scale droughts in this macro-region. Theoretically, such events could be driven by global tele-connections and/or common astronomic cycles. We have attempted the precipitation reconstructions of two distant (similar to 1000 km) intermountain valleys in South Siberia, based on the tree ring width of Pinus sylvestris L. To enhance the quality of the precipitation reconstruction models, networks of existing tree-ring data were expanded and daily precision of instrumental precipitation series was implemented for calibration. Within-region (150-200 km) common signal between local chronologies r = 0.37-0.90 (p < 0.05) allowed obtaining regional ones, registering precipitation up to annual temporal scale. High correlations of both regional chronologies with annual precipitation were found for period from previous July 22 to current July 21 (r = 0.71-0.72). These precipitation series were further reconstructed. Reconstruction models explaining 50-52% of variation were developed for the years 1753-2015 and 1798-2015. Although both valleys do not record many concurrent extreme precipitation events, some common and opposite extremes have been revealed. For both regions, an 11-year and 26-29-year cycles were commonly observed. These were probably associated with the solar activity and Pacific Decadal Oscillation (PDO). However, phase shifts of these cycles were recorded between the regions and with PDO. Stronger impact of oceanic air masses was observed in the eastern one of the two considered territories. Whereas higher significance of frequencies associated with astronomic cycles (solar and lunar-nodal) was found in the western one.

Automated summary

Tree rings from forest-steppes of temperate continental Asia serve as valuable proxies for reconstructing moisture regimes in the area, capturing environmental changes such as climate warming and drought variations. The study highlights the complexity of precipitation heterogeneity and the potential for large-scale droughts in the region. Reconstruction models based on tree ring data from two distant intermountain valleys in South Siberia show strong correlations with annual precipitation, revealing common and opposite extremes and cyclic patterns related to solar activity and Pacific Decadal Oscillation (PDO). Differences in the impact of oceanic air masses and astronomic cycles between the two regions are also noted.