Warming trends in Asia amplified by brown cloud solar absorption
Warming trends in Asia amplified by brown cloud solar absorption
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DOI：
10.1038/nature06019
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发表时间：
2007-08
期刊：
影响因子：
64.8
通讯作者：
V. Ramanathan;M. V. Ramana;G. Roberts;Dohyeong Kim;C. Corrigan;C. Chung;D. Winker
中科院分区：
文献类型：
--
作者：
V. Ramanathan;M. V. Ramana;G. Roberts;Dohyeong Kim;C. Corrigan;C. Chung;D. Winker
大气棕色云主要是生物质燃烧和化石燃料消耗的结果。它们由光吸收和光散射气溶胶的混合物组成，因此有助于大气太阳能加热和表面冷却。两个气候强迫项之和净气溶胶强迫效应被认为是负的，可能掩盖了近一半的温室气体快速增加导致的全球变暖。然而，气溶胶强迫效应至少有四倍的不确定性。大气太阳能加热是不确定性的一个重要来源，因为目前的估计主要来自模型研究。在这里，我们使用三个轻型无人驾驶飞行器，它们垂直堆叠在污染的印度洋上空0.5至3公里处。这些无人驾驶飞行器部署了测量气溶胶浓度、烟尘量和太阳通量的微型仪器。在18次飞行任务中，三架无人驾驶航空器的水平间隔为几十米或更短，时间间隔不到10秒，这使得有可能直接测量大气层太阳加热率。我们发现，大气棕色云增强低层大气太阳能加热约50%.Our大气环流模式模拟，考虑到最近观察到的垂直延伸的大气棕色云在印度洋和亚洲的广泛发生，表明大气棕色云的贡献一样多，最近增加的人为温室气体区域低层大气变暖趋势。我们认为，每十年0.25 K的综合变暖趋势可能足以解释所观察到的喜马拉雅冰川退缩。
Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms—the net aerosol forcing effect—is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers,,.