Influence of the Tian Shan on Arid Extratropical Asia
Influence of the Tian Shan on Arid Extratropical Asia
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DOI：
10.1175/jcli-d-15-0490.1
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发表时间：
2016-08-01
影响因子：
4.9
通讯作者：
Vecchi, Gabriel
中科院分区：
文献类型：
--
作者：
Baldwin, Jane;Vecchi, Gabriel
干旱的温带亚洲（AEA）被湿润的天山（青藏高原的北部分支）一分为二，分为东部和西部沙漠，每个沙漠都有独特的气候特征。东部沙漠（北纬35度—55度，东经45度—75度）夏季降水最大，北纬35度—55度，东经45度—75度西部沙漠最大。运行一个新的高分辨率（50 公里大气-陆地）全球耦合气候模型，并移除天山，以确定这些山脉是否是 AEA 气候东西分异的原因。对 Control 和 NoTianshan 运行的百年模拟突出显示了天山的统计显着影响。总体而言，天山被发现增强了整个 AEA 的降水季节性梯度，主要是通过改变东部沙漠。天山通过阻挡西部冬季降水、增强该地区的沉降以及增加东部夏季降水，极大地改变了塔克拉玛干沙漠直接向其东部（AEA最干燥的部分）的降水季节。天山通过两种机制增加东部夏季降水：1）地形降水，夏季天山东缘降水量最大；2）通过改变更大规模的季节性平均大气环流，远程增强东亚夏季风。由于积雪减少和相应的反照率下降，东部冬季降水的减少也导致天山东北部和东南部的阿尔泰山和昆仑山的远程变暖。
Arid extratropical Asia (AEA) is bisected at the wetter Tian Shan (a northern offshoot of the Tibetan Plateau) into east and west deserts, each with unique climatological characteristics. The east deserts (similar to 35 degrees-55 degrees N, similar to 45 degrees-75 degrees E) have a summer precipitation maximum, and the west deserts (similar to 35 degrees-55 degrees N, similar to 45 degrees-75 degrees E) have a winter-spring precipitation maximum. A new high-resolution (50 km atmosphere-land) global coupled climate model is run with the Tian Shan removed to determine whether these mountains are responsible for the climatological east-west differentiation of AEA. Multicentennial simulations for the Control and NoTianshan runs highlight statistically significant effects of the Tian Shan. Overall, the Tian Shan are found to enhance the precipitation seasonality gradient across AEA, mostly through altering the east deserts. The Tian Shan dramatically change the precipitation seasonality of the Taklimakan Desert directly to its east (the driest part of AEA) by blocking west winter precipitation, enhancing subsidence over this region, and increasing east summer precipitation. The Tian Shan increase east summer precipitation through two mechanisms: 1) orographic precipitation, which is greatest on the eastern edge of the Tian Shan in summer, and 2) remote enhancement of the East Asian summer monsoon through alteration of the larger-scale seasonal mean atmospheric circulation. The decrease in east winter precipitation also generates remote warming of the Altai and Kunlun Shan, mountains northeast and southeast of the Tian Shan, respectively, due to reduction of snow cover and corresponding albedo decrease.