Influence of atmospheric internal variability on the long-term Siberian water cycle during the past 2 centuries
Influence of atmospheric internal variability on the long-term Siberian water cycle during the past 2 centuries
复制标题
DOI：
10.5194/esd-9-497-2018
复制
发表时间：
2017-06
期刊：
影响因子：
--
通讯作者：
K. Oshima;Koto Ogata;Hotaek Park;Y. Tachibana
中科院分区：
文献类型：
--
作者：
K. Oshima;Koto Ogata;Hotaek Park;Y. Tachibana
抽象的。西伯利亚的河流流量是北冰洋淡水的一大来源，而西伯利亚流量长期变化的原因尚不清楚。观测到的东部Lena和西部Ob的河流流量表明，在过去70年的每个时期，不同时期的河流流量关系不同。20世纪80年代至90年代中期，两条河流流量之间呈负相关，50年代中期至60年代为正相关，90年代中期后减弱。更多的树木年轮重建放电的长期记录也显示出每个时代的相关性不同。值得注意的是，在过去的两个世纪里，从重建中获得的相关性往往是负的。这种趋势也是从观测中的降水以及在为气专委第四次评估报告而进行的大气环流模式和完全耦合的大气-海洋模式的模拟中得出的。AGCM控制模拟进一步证明，西伯利亚夏季大尺度大气环流的东西向拉锯型是一种大气内部变率。这导致了Lena和Ob上的降水异常相反，并呈负相关。因此，西伯利亚东西向拉锯型夏季大气内部变率是影响西伯利亚降水和河流流量长期变化的关键因素，即该地区的水循环。
Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, whereas the cause of the long-term variation in Siberian discharges is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past 7 decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. More long-term records of tree-ring-reconstructed discharges have also shown differences in the correlations in each of the epochs. It is noteworthy that the correlations obtained from the reconstructions tend to be negative during the past 2 centuries. Such tendency has also been obtained from precipitations in observations, and in simulations with an atmospheric general circulation model (AGCM) and fully coupled atmosphere–ocean GCMs conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime large-scale atmospheric circulation frequently emerges over Siberia as an atmospheric internal variability. This results in an opposite anomaly of precipitation over the Lena and Ob and the negative correlation. Consequently, the summertime atmospheric internal variability in the east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.