A study of the direct and indirect effects of aerosols using global satellite data sets of aerosol and cloud parameters
A study of the direct and indirect effects of aerosols using global satellite data sets of aerosol and cloud parameters
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DOI：
10.1029/2002jd003359
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发表时间：
2003-11-21
影响因子：
4.4
通讯作者：
Mukai, S
中科院分区：
文献类型：
--
作者：
Sekiguchi, M;Nakajima, T;Mukai, S
本文研究了卫星遥感气溶胶和云参数之间的相关性，以评估气溶胶间接效应的辐射强迫。全球统计结果表明，气溶胶粒子的有效半径和光学厚度与气溶胶粒子的柱数浓度有很好的相关性，表明气溶胶的间接效应。云分数与气溶胶数的相关性也被看到，而我们不能找到一个显着的云顶温度与气溶胶柱数的相关性。此外，区域统计表明，云光学厚度和云分数与气溶胶柱数浓度之间的正相关关系存在于大部分地区与全球平均统计相一致。然而，有效云粒子半径仅在沿海地区表现出与全球相关性相似的趋势。利用这些相关性，并假设气溶胶柱数浓度比前工业时代增加了30%，气溶胶间接效应的总辐射强迫估计约为-0.6 ~-1.2 W m（-2）。由卫星反演的气溶胶直接效应的辐射强迫在海洋上也被评估为-0.4W m（-2）。云顶温度对气溶胶数的变化不敏感，尽管气溶胶数与云温度之间存在明显的负相关，在云温度下，云粒子的半径增长到14 mm。这种特殊的云温度依赖性表明，气溶胶作用于云，从而改变云顶附近的云粒子大小，光学厚度，和分数，但保持他们的云顶温度，而不造成显着的长波辐射强迫。
The present study investigated the correlations between aerosol and cloud parameters derived from satellite remote sensing for evaluating the radiative forcing of the aerosol indirect effect. The global statistics showed that the effective particle radius and the optical thickness of low clouds correlate well with the column number concentration of the aerosol particles, indicating an aerosol indirect effect. A correlation of the cloud fraction with the aerosol number was also seen, whereas we could not find a significant correlation of the cloud-top temperature with the column aerosol number. Furthermore, the regional statistics presented that positive correlations between the cloud optical thickness and cloud fraction with the aerosol column number concentration exist in most regions consistent with the global mean statistics. However, the effective cloud particle radius showed a tendency similar to the global correlation only around the seashore regions. Using these correlations and assuming that the aerosol column number concentration has increased by 30% from the preindustrial era, the total radiative forcing of the aerosol indirect effect was evaluated to be about -0.6 to -1.2 W m(-2). The radiative forcing of the aerosol direct effect from the satellite-retrieved parameters was also evaluated as -0.4 W m(-2) over the ocean. The cloud-top temperature was found to be insensitive to the change in the aerosol number, although there was a distinct negative correlation between the aerosol number and cloud temperature at which the cloud particle grows to a radius of 14 mm. This particular dependency of the cloud temperature suggests that aerosols acts on clouds so as to change cloud particle size near the cloud top, optical thickness, and fraction but to keep their cloud-top temperature without causing a significant longwave radiative forcing.