Whither the 100th Meridian? The Once and Future Physical and Human Geography of America’s Arid–Humid Divide. Part I: The Story So Far
Whither the 100th Meridian? The Once and Future Physical and Human Geography of America’s Arid–Humid Divide. Part I: The Story So Far
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第 100 条子午线在哪里？
DOI：
10.1175/ei-d-17-0011.1
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发表时间：
2018
影响因子：
2
通讯作者：
Henderson, Naomi
中科院分区：
文献类型：
--
作者：
Seager, Richard;Lis, Nathan;Feldman, Jamie;Ting, Mingfang;Williams, A. Park;Nakamura, Jennifer;Liu, Haibo;Henderson, Naomi
19世纪，约翰·韦斯利·鲍威尔提出了100度经线将北美大陆划分为干旱的西部地区和潮湿的东部地区的概念。这一概念仍然牢牢地存在于国家的想象中。从气候、水文、植被、土地利用、聚落和农业经济等方面对其进行了重新审视。结果表明，大约在经线100度处，干旱存在明显的东西梯度，这一点在水文气候、土壤水分和“潜在植被”中得到了很好的体现。这种梯度是由大气环流和水汽输送引起的。在冬季，100度经线以西的干旱地区不受太平洋风暴相关降水的影响，而且距离太远，无法从大西洋风暴中受益。夏季，北大西洋副热带高压西侧的南风气流在西部平原上有西风成分，将来自西南内陆的空气带到东部平原，但也将来自墨西哥湾的空气带到东部平原，产生由西向东的水汽输送和降水梯度。干旱梯度体现在土壤水分和由西向东由短草向高草草原的过渡过程中。这种梯度很大，因为100度经线以东的已开发土地的覆盖率比西经的要大。子午线以西的农场较少，但面积较大，反映出土地生产力较低。小麦和玉米的种植优先发生在100度子午线以西和以东。100经线是一条非常真实的自然气候和自然景观的干湿分水岭，对人类聚落和农业发展产生了强大的影响。
John Wesley Powell, in the nineteenth century, introduced the notion that the 100th meridian divides the North American continent into arid western regions and humid eastern regions. This concept remains firmly fixed in the national imagination. It is reexamined in terms of climate, hydrology, vegetation, land use, settlement, and the agricultural economy. It is shown there is a stark east–west gradient in aridity roughly at the 100th meridian that is well expressed in hydroclimate, soil moisture, and “potential vegetation.” The gradient arises from atmospheric circulations and moisture transports. In winter, the arid regions west of the 100th meridian are shielded from Pacific storm-related precipitation and are too far west to benefit from Atlantic storms. In summer, the southerly flow on the western flank of the North Atlantic subtropical high has a westerly component over the western plains, bringing air from the interior southwest, but it also brings air from the Gulf of Mexico over the eastern plains, generating a west–east moisture transport and precipitation gradient. The aridity gradient is realized in soil moisture and a west-to-east transition from shortgrass to tallgrass prairie. The gradient is sharp in terms of greater fractional coverage of developed land east of the 100th meridian than to the west. Farms are fewer but larger west of the meridian, reflective of lower land productivity. Wheat and corn cultivation preferentially occur west and east of the 100th meridian, respectively. The 100th meridian is a very real arid–humid divide in the physical climate and landscape, and this has exerted a powerful influence on human settlement and agricultural development.
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影响因子：
2.9
作者：
E. N. Transeau
通讯作者：
E. N. Transeau
DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
W. Drummond;Clarence E. Dutton;Grove Karl Gilbert;J. W. Powell;A. H. Thompson
通讯作者：
A. H. Thompson
DOI：
--
发表时间：
1987
期刊：
影响因子：
--
作者：
Bradley H. Baltensperger
通讯作者：
Bradley H. Baltensperger
影响因子：
2
作者：
Seager, Richard;Feldman, Jamie;Lis, Nathan;Ting, Mingfang;Williams, Alton P.;Nakamura, Jennifer;Liu, Haibo;Henderson, Naomi
通讯作者：
Henderson, Naomi
从整体上看事物
DOI：
--
发表时间：
2005
期刊：
影响因子：
--
作者：
Frances Hesselbein
通讯作者：
Frances Hesselbein