Net radiative effects of dust in the tropical North Atlantic based on integrated satellite observations and in situ measurements
Net radiative effects of dust in the tropical North Atlantic based on integrated satellite observations and in situ measurements
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DOI：
10.5194/acp-18-11303-2018
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发表时间：
2018-08
影响因子：
6.3
通讯作者：
Qianqian Song;Zhibo Zhang;Hongbin Yu;S. Kato;P. Yang;P. Colarco;L. Remer;C. Ryder
中科院分区：
文献类型：
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作者：
Qianqian Song;Zhibo Zhang;Hongbin Yu;S. Kato;P. Yang;P. Colarco;L. Remer;C. Ryder
抽象。在这项研究中，我们整合了最近的现场测量与卫星反演的尘埃物理和辐射特性，以量化尘埃直接辐射效应的短波（SW）和长波（LW）辐射（表示为DRESW和DRELW，分别）在热带北大西洋在2007年至2010年的夏季。通过CERES测量的大气层顶（TOA）通量与卫星气溶胶光学厚度（AOD）反演的线性回归，我们估计在TOA的瞬时DRESW效率分别为-49.7 7. 1 W m−2 AOD−1和-36.5 4. 8 W m−2 AOD−1。然后，我们根据最近对尘埃颗粒尺寸分布（PSD）、折射率和颗粒形状分布的测量进行了各种灵敏度研究，以确定尘埃微物理和光学性质如何影响DRE估计及其与上述卫星得出的DRE的一致性。我们的分析表明，一个很好的协议与基于观测的估计瞬时DRESW和DRELW可以实现通过最近观察到的PSD与大量存在的粗颗粒，一个较低的吸收SW折射率，和球体形状的组合。基于尘埃物理性质的最佳组合，我们进一步估计了TOA和地面分别为−10 W m−2和−26 W m−2的昼夜平均尘埃DRESW，其中30%被正DRELW抵消。由此得出TOA和地表的净DRE分别约为−6.9和−18.3 W m−2。我们的研究表明，LW通量包含有用的信息，尘埃粒子的大小，这可以用来与SW的观测，以实现更全面的了解尘埃辐射效应。
Abstract. In this study, we integrate recent in situ measurements with satellite retrievals of dust physical and radiative properties to quantify dust direct radiative effects on shortwave (SW) and longwave (LW) radiation (denoted as DRESW and DRELW, respectively) in the tropical North Atlantic during the summer months from 2007 to 2010. Through linear regression of the CERES-measured top-of-atmosphere (TOA) flux versus satellite aerosol optical depth (AOD) retrievals, we estimate the instantaneous DRESW efficiency at the TOA to be -49.7±7.1 W m−2 AOD−1 and -36.5±4.8 W m−2 AOD−1 based on AOD from MODIS and CALIOP, respectively. We then perform various sensitivity studies based on recent measurements of dust particle size distribution (PSD), refractive index, and particle shape distribution to determine how the dust microphysical and optical properties affect DRE estimates and its agreement with the above-mentioned satellite-derived DREs. Our analysis shows that a good agreement with the observation-based estimates of instantaneous DRESW and DRELW can be achieved through a combination of recently observed PSD with substantial presence of coarse particles, a less absorptive SW refractive index, and spheroid shapes. Based on this optimal combination of dust physical properties we further estimate the diurnal mean dust DRESW in the region of −10 W m−2 at TOA and −26 W m−2 at the surface, respectively, of which ∼ 30 % is canceled out by the positive DRELW. This yields a net DRE of about −6.9 and −18.3 W m−2 at TOA and the surface, respectively. Our study suggests that the LW flux contains useful information on dust particle size, which could be used together with SW observations to achieve a more holistic understanding of the dust radiative effect.