NOAA/WDS Paleoclimatology - Babushkina - Malaya Nichka - PISY - ITRDB RUSS308

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 (~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.

温带大陆性亚洲森林草原带的树木年轮是用于区域水分状况重建的可靠代用指标，可涵盖气候变暖、干旱发生频率与强度变化等多重环境波动。降水的区域异质性使得这一宏观区域内大范围空间尺度干旱事件的发生概率问题悬而未决。理论上，此类大范围干旱事件可能由全球遥相关作用或共同的天文周期驱动。本研究基于西伯利亚南部两处相距约1000公里的山间河谷的欧洲赤松（*Pinus sylvestris L.*）年轮宽度数据，尝试开展降水序列重建工作。为提升降水重建模型的精度，本研究扩充了现有树木年轮数据集网络，并采用日分辨率的器测降水序列进行校准。区域内（150~200公里范围）各当地年轮年表间的共同信号相关系数为0.37~0.90（p<0.05），据此可构建区域年轮年表，其可反映年尺度的降水变化。研究发现，两处区域的年轮年表与前一年7月22日至当年7月21日时段的年降水量均呈现高度相关，相关系数达0.71~0.72，据此进一步重建了两地的降水序列。本研究分别为1753~2015年与1798~2015年时段构建了可解释50%~52%降水变异的重建模型。尽管两处河谷并未记录到大量同步发生的极端降水事件，但仍识别出若干共同及反向的极端降水事件。两处区域均普遍存在11年以及26~29年的周期信号，推测其与太阳活动及太平洋年代际振荡（Pacific Decadal Oscillation, PDO）相关。但两处区域的周期相位以及其与PDO的相位均存在偏移。研究区域东侧受海洋气团的影响更为显著，而西侧则表现出天文周期（太阳及月结点周期）相关频率具有更高的显著性。