Altered hydrologic feedback in a warming climate introduces a ''warming hole''
Altered hydrologic feedback in a warming climate introduces a ''warming hole''
复制标题
DOI：
10.1029/2004gl020528
复制
发表时间：
2004-09-10
影响因子：
5.2
通讯作者：
Segal, M
中科院分区：
文献类型：
--
作者：
Pan, ZT;Arritt, RW;Segal, M
在20世纪世纪的最后25年中，大多数主要陆地地区都经历了夏季变暖的趋势，但美国中部地区的气温却下降了0.2-0.8 K。相比之下，大多数使用GCM的气候预测显示，包括北美在内的所有大陆内部都在变暖。我们研究了这种差异，使用区域气候模式，并发现在增强温室气体浓度下的环流-降水耦合，发生在尺度太小，目前的GCM解决得很好。结果表明，在美国中部（一个“暖洞”）与低层环流的变化，导致季节性枯竭的土壤水分补充，从而增加夏末蒸散和抑制白天最高温度的局部最低变暖。这些区域尺度的反馈过程可以部分解释在美国中部观测到的世纪末的温度趋势，并可能降低该地区未来温室效应的幅度。
In the last 25 years of the 20th century most major land regions experienced a summer warming trend, but the central U.S. cooled by 0.2-0.8 K. In contrast most climate projections using GCMs show warming for all continental interiors including North America. We examined this discrepancy by using a regional climate model and found a circulation-precipitation coupling under enhanced greenhouse gas concentrations that occurs on scales too small for current GCMs to resolve well. Results show a local minimum of warming in the central U.S. (a "warming hole") associated with changes in low-level circulations that lead to replenishment of seasonally depleted soil moisture, thereby increasing late-summer evapotranspiration and suppressing daytime maximum temperatures. These regional-scale feedback processes may partly explain the observed late 20th century temperature trend in the central U.S. and potentially could reduce the magnitude of future greenhouse warming in the region.