Spatial distribution, temporal variation, and transport characteristics of atmospheric water vapor over Central Asia and the arid region of China
Spatial distribution, temporal variation, and transport characteristics of atmospheric water vapor over Central Asia and the arid region of China
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DOI：
10.1016/j.gloplacha.2018.06.007
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发表时间：
2019-01
影响因子：
3.9
通讯作者：
Xuefeng Guan;Lianmei Yang;Yingxin Zhang;Jiangang Li
中科院分区：
文献类型：
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作者：
Xuefeng Guan;Lianmei Yang;Yingxin Zhang;Jiangang Li
本研究基于 ERA-中期再分析数据，评估了 1979-2012 年期间 CA-AC 上空水汽的空间分布、季节/年度变化和输运特征。 (1) CA—AC地处中低纬低湿区，南部、西部和平原地区水汽含量较北部、东部和山区丰富。 1979-2012年年平均可降水汽含量（PWC）呈下降趋势，这可能是由于冬季PWC的减少所致。 CA-AC年际PWC不存在明显的年际和年代际变化，但季节平均PWC在不同时间尺度上存在年际变化。(2)CA-AC春、秋、冬季水汽主要来源于地中海、黑海和里海，夏季主要来源于大西洋和欧洲大陆高纬度地区。 (3)中亚大部分地区春夏季水汽发散，冬季水汽辐合。中亚的吉尔吉斯斯坦、塔吉克斯坦和中国干旱地区的新疆北部，水汽常年汇聚。然而，南疆、巴丹吉林沙漠和腾格里沙漠却常年出现水汽辐散。 (4) 中亚五国的水汽输送主要是沿西部和南部边界输入，沿南部和东部边界输出。在我国干旱地区，水汽输送主要是沿西部和北部边界输入，沿东部边界输出。 (5) 1979—2012年中亚地区水汽通量为正值，中国干旱区水汽通量为负值。发现CA-AC的净水汽通量春季减少，冬季增加，秋季和夏季基本保持不变。 (6) 西风指数对CA-AC水汽输送具有指示作用。在西风指数较大的年份，纬向环流将足够强大，将有更多的水汽到达CA和AC的中东部地区。由于西风指数较小，更多的水汽将被输送到加利福尼亚州西部，而由于纵向水汽输送的加强，空调上空的水汽流入量显着减少。
This study evaluated the spatial distribution, seasonal/annual variability, and transport characteristics of water vapor over CA–AC during the period 1979–2012, based on ERA-Interim reanalysis data. (1) Located in a low-moisture area of the mid- to low latitudes, CA–AC has a richer water vapor in the south and west, and the plain area than that in the north and east, and the mountainous regions. A decreasing trend of annual average precipitable water-vapor content (PWC) was detected during 1979–2012, which could be attributed to the decrease of PWC in winter. There is no obvious interannual and interdecadal variation of annual CA–AC PWC but the seasonal mean PWC have interannual variability at different time scales.(2) Water vapor in CA–AC is derived primarily from the Mediterranean, Black, and Caspian seas in spring, autumn, and winter, but from the Atlantic Ocean and high latitudes of the European continent in summer. (3) Most of Central Asia is characterized by water vapor divergence in spring and summer and by water vapor convergence in winter. Water vapor converges throughout the year in Kyrgyzstan and Tajikistan in Central Asia and in northern Xinjiang in the arid region of China. Perennial water vapor divergence, however, occurs in southern Xinjiang and in the Badain Jaran and Tengger deserts. (4) Water vapor transport for the five studied countries of Central Asia is mainly via input along the western and southern boundaries and output along the southern and eastern boundaries. In the arid region of China, water vapor transport is mainly via input along the western and northern boundaries and output along the eastern boundary. (5) Water vapor flux was positive in Central Asia but negative in the arid region of China during 1979–2012. The net water vapor flux of CA–AC was found to decrease in spring, increase in winter, and remain largely constant in autumn and summer. (6) Westerly Wind Index can act as an indicative role for water vapor transport in CA–AC. In years with larger Westerly Wind Index, the zonal circulation will be strong enough to bring more water vapor reaching the middle and east part of CA and the AC. More water vapor will be transported to the western part of CA with smaller Westerly Wind Index, while water vapor influx decreases remarkably over the AC because of the intensified longitudinal water vapor transport.