Sensitivity of direct radiative forcing by mineral dust to particle characteristics
Sensitivity of direct radiative forcing by mineral dust to particle characteristics
复制标题
DOI：
10.1177/0309133309105034
复制
发表时间：
2009-02
期刊：
影响因子：
--
通讯作者：
A. Durant;S. Harrison;I. M. Watson;Y. Balkanski
中科院分区：
文献类型：
--
作者：
A. Durant;S. Harrison;I. M. Watson;Y. Balkanski
气载尘埃影响地球的能量平衡--这种影响是根据大气层顶部净辐射（或辐射强迫，W m-2）的隐含变化来衡量的。在目前的气候条件下，气载沙尘直接强迫的大小和迹象仍有相当大的不确定性。这种不确定性大部分来自于对矿物尘埃-颗粒大小、成分和形状的简化假设，这些假设被用于尘埃特征的遥感反演和尘埃循环模型。要改进对尘埃直接辐射强迫的估计，就需要改进对粒子特性空间变异性的描述，以提供可靠的尘埃光学特性信息。这包括对以下方面的限制：（1）颗粒大小分布，包括颗粒亚群的区分和10 μm以下至<0.1 μm质量分数的粉尘量的量化;（2）颗粒组成，特别是氧化铁的丰度，以及颗粒是否由单一或多矿物颗粒组成;（3）颗粒形状，包括球形度和表面粗糙度，作为大小和矿物学的函数;以及（4）灰尘颗粒聚集在一起的程度。使用测量单个颗粒的大小、组成和形状的技术将为光学建模提供更好的基础。
Airborne dust affects the Earth's energy balance — an impact that is measured in terms of the implied change in net radiation (or radiative forcing, in W m-2) at the top of the atmosphere. There remains considerable uncertainty in the magnitude and sign of direct forcing by airborne dust under current climate. Much of this uncertainty stems from simplified assumptions about mineral dust-particle size, composition and shape, which are applied in remote sensing retrievals of dust characteristics and dust-cycle models. Improved estimates of direct radiative forcing by dust will require improved characterization of the spatial variability in particle characteristics to provide reliable information dust optical properties. This includes constraints on: (1) particle-size distribution, including discrimination of particle subpopulations and quantification of the amount of dust in the sub-10 µm to <0.1 µm mass fraction; (2) particle composition, specifically the abundance of iron oxides, and whether particles consist of single or multi-mineral grains; (3) particle shape, including degree of sphericity and surface roughness, as a function of size and mineralogy; and (4) the degree to which dust particles are aggregated together. The use of techniques that measure the size, composition and shape of individual particles will provide a better basis for optical modelling.