Anber Usama, Gentine Pierre, Wang Shuguang, Sobel Adam H
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027;
Department of Earth and Environmental Engineering and Earth Institute, Columbia University, New York, NY 10027;
Proc Natl Acad Sci U S A. 2015 Sep 15;112(37):11473-7. doi: 10.1073/pnas.1505077112. Epub 2015 Aug 31.
The diurnal and seasonal water cycles in the Amazon remain poorly simulated in general circulation models, exhibiting peak evapotranspiration in the wrong season and rain too early in the day. We show that those biases are not present in cloud-resolving simulations with parameterized large-scale circulation. The difference is attributed to the representation of the morning fog layer, and to more accurate characterization of convection and its coupling with large-scale circulation. The morning fog layer, present in the wet season but absent in the dry season, dramatically increases cloud albedo, which reduces evapotranspiration through its modulation of the surface energy budget. These results highlight the importance of the coupling between the energy and hydrological cycles and the key role of cloud albedo feedback for climates over tropical continents.
在大气环流模型中，亚马逊地区的昼夜和季节水循环总体上仍模拟得很差，表现为蒸散峰值出现在错误的季节，降雨时间过早。我们表明，在具有参数化大尺度环流的云分辨模拟中不存在这些偏差。这种差异归因于晨雾层的表现，以及对流及其与大尺度环流耦合的更精确表征。晨雾层出现在湿季但在干季不存在，它会显著增加云反照率，通过调节地表能量平衡来减少蒸散。这些结果突出了能量和水文循环耦合的重要性，以及云反照率反馈对热带大陆气候的关键作用。
