Major increase in winter and spring precipitation during the Little Ice Age in the westerly dominated northern Qinghai-Tibetan Plateau
Major increase in winter and spring precipitation during the Little Ice Age in the westerly dominated northern Qinghai-Tibetan Plateau
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DOI：
10.1016/j.quascirev.2018.09.022
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发表时间：
2018-11
影响因子：
4
通讯作者：
Jiaju Zhao;E. Thomas;Yuan Yao;J. deAraujo;Yongsong Huang
中科院分区：
文献类型：
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作者：
Jiaju Zhao;E. Thomas;Yuan Yao;J. deAraujo;Yongsong Huang
利用长链烯烃（LCAs）进行盐湖古温度和古盐度重建的尝试有很多。然而，盐湖中的lca通常由多种触生植物产生，这可能会混淆数据解释。我们发现LCA不饱和比在仪器期间呈逐步跳跃，很可能是由于主导烯烃生产商的突然转变。C37:4烯酮的百分比（%C37:4）与春季和冬春联合降水量有较强的相关性（R2= 0.83和R2= 0.81）。我们推测，冬春降水的增加导致春季融化后湖泊表层水的新鲜度增加，促进了早开的共生植物产生更多的lca，其% c37:4值相对较高。扩展仪器校准下核使我们能够定量地重建过去千年的区域春季和冬春降水。小冰期冬春降水显著增加，特别是在太阳活动极小期。
There have been numerous attempts to use long-chain alkenones (LCAs) in saline lakes for paleotemperature and paleosalinity reconstructions. However, LCAs in saline lakes are often produced by multiple haptophyte species, which may confound data interpretations. Here we analyzed LCAs in a finely laminated, high sedimentation rate core from the hypersaline Lake Gahai in the northern Qinghai-Tibetan Plateau and compared our results with regional instrumental records. We find that LCA unsaturation ratios display a stepwise jump during the instrumental period, most likely originating from a sudden shift in the dominant alkenone producers. In contrast, the percentage of the C37:4alkenone (%C37:4) displays strong correlations with spring and combined winter-spring precipitation amount (R2= 0.83 and R2= 0.81, respectively). We hypothesize that high winter-spring precipitation leads to greater freshening of lake surface water immediately after spring melting, promoting greater production of LCAs with relatively high %C37:4values by the early blooming haptophyte species. Extending the instrumental calibration downcore allows us to quantitatively reconstruct regional spring and winter-spring precipitation for the past millennium. We find a major increase in winter-spring precipitation during the Little Ice Age (LIA), especially during the phases of solar minima. Our finding provides novel quantitative support to the previous studies suggesting relatively wet conditions during the LIA in the westerly dominated regions of central Asia and northern Tibetan Plateau and infers a substantial increase in regional winter-spring precipitation should the predicted grand solar minimum in the forthcoming decades become a reality.