The dust direct radiative effect (DRE) depends strongly on the dust particle size distribution (PSD) and complex refractive index (CRI). Although recent studies constrained the dust PSD in the models, its CRI uncertainties are still large. As a result, whether dust warms or cools the climate system remains unclear. Here, we estimate the dust DRE by employing the regionally-dependent dust CRI based on global measurements. We find that new dust CRI significantly enhances the scattering of dust in the shortwave while reduces its absorption in the longwave, which is opposite to that caused by increasing the coarse and giant dust fraction via constraining the PSD. Constraining both PSD and CRI ultimately leads to a net dust DRE of −0.68 W m⁻², a cooling stronger than current model estimates.

中文翻译：

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根据区域相关的折射率估算出更大的粉尘冷却效果

粉尘直接辐射效应 (DRE) 在很大程度上取决于粉尘粒径分布 (PSD) 和复折射率 (CRI)。尽管最近的研究在模型中限制了灰尘PSD，但其CRI不确定性仍然很大。因此，灰尘是否使气候系统变暖或变冷仍不清楚。在这里，我们通过采用基于全球测量的区域相关灰尘 CRI 来估计灰尘 DRE。我们发现，新的尘埃 CRI 显着增强了尘埃在短波中的散射，同时减少了其在长波中的吸收，这与通过限制 PSD 增加粗大尘埃部分所造成的效果相反。限制 PSD 和 CRI 最终导致净尘埃 DRE 为 -0.68 W m ^-2，冷却效果比当前模型估计的更强。