Both the atmospheric and land surface conditions affect the dust cycle in the climate system. In particular, the occurrence of drought can modulate the emission of dust on interannual time scales. Studies have shown, however, that models generally do not represent dust variability, and that there is a large intermodel spread in the simulation of dust. In this study, we compare the relationship between drought and dust in 19 Global Circulation Models participating in Phase Six of the Coupled Model Intercomparison Project for historical (1950–2014) and future (2050–2100: SSP585) scenarios and MERRA-2 reanalysis. The relationships between drought and dust (dust sensitivity to drought) are based on linear regression analysis. Our results show that MERRA-2 reanalysis highly underestimates models' average dust emission. The Standardized Soil Moisture Index better explains the dust variability over most regions than the Standardized Precipitation Index, highlighting the importance of the condition of the land surface. Across models, the strength of the dust-drought relationship explains much of the spread in interannual variability of dust emission over Southern Africa, Sahel, India, Australia, and North America, indicating models that capture this relationship generate greater variability. We also find that the correlation between models' dust-drought relationship and mean emission is generally weaker compared to that with dust variability. In future scenarios, the intermodel spread in the projected changes in the dust variability is correlated to the intermodel spread in the projected changes in the models' dust sensitivity to drought in Australia, India, Middle East, South America, and Southern Africa.

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CMIP6 模型中干旱敏感性解释的全球沙尘变异性

大气和地表条件都会影响气候系统中的尘埃循环。特别是干旱的发生可以在年际时间尺度上调节沙尘的排放。然而，研究表明，模型通常不代表沙尘的可变性，并且在沙尘模拟中存在很大的模型间传播。在这项研究中，我们比较了参与历史（1950-2014）和未来（2050-2100：SSP585）情景和MERRA-2再分析耦合模型比对项目第六阶段的19个全球环流模型中干旱和沙尘之间的关系。干旱与沙尘之间的关系（沙尘对干旱的敏感性）基于线性回归分析。我们的结果表明，MERRA-2 再分析严重低估了模型的平均粉尘排放量。标准化土壤水分指数比标准化降水指数更好地解释了大多数地区的沙尘变化，突出了地表状况的重要性。在所有模型中，沙尘-干旱关系的强度解释了南部非洲、萨赫勒、印度、澳大利亚和北美沙尘排放年际变化的大部分分布，表明捕捉这种关系的模型会产生更大的变化。我们还发现模型的沙尘-干旱关系与平均排放之间的相关性与沙尘变异性相比通常较弱。在未来的情景中，预测的沙尘变异性变化中的模型间传播与澳大利亚模型对干旱的沙尘敏感性预测变化中的模型间传播相关，