The U.S. Southwest is naturally prone to dust and drought. With a high risk of unprecedented drought in the future due to climate change, changes in the dust cycle are expected. Whereas paleo records of dust deposition from the region suggest that past megadroughts did not coincide with elevated dust levels, modern studies indicate higher dust during drier conditions. To examine this disagreement, we compare regional paleo records to output from the Community Earth System Model Last Millennium Ensemble experiment. We investigate the role of hydroclimate on dust emissions in the model and analyze how modeled dust during megadroughts compares to all other years. We find that bare ground, as directly modulated by the density of vegetation cover and indirectly by hydroclimate, is the primary control on simulated dust emissions in the Southwest. Furthermore, we find slightly (but significantly) higher dust emission during megadroughts than during years without megadroughts in the model. Using a simple forward modeling approach to assess the impact of age uncertainty in the regional dust records, we find that age uncertainty can explain most of the paleo data/model disagreement. The remaining difference could be related to processes that are not included in the model that inhibit dust emissions during drought, including brown vegetation and soil crusts. Our results suggest the dust‐drought nexus is a continuum and that the impact of drought on dust cycling is subtle.

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美国西南部的沙尘暴连结：一种代理模型比较方法

美国西南部自然容易发生尘土和干旱。由于气候变化，未来极有可能发生前所未有的干旱，因此尘埃循环将发生变化。尽管该地区尘埃沉积的古记录表明过去的特大干旱与尘埃含量升高并不吻合，但现代研究表明，在较干燥的条件下尘埃含量较高。为了检查这种分歧，我们将区域古记录与“社区地球系统模型上次千年合奏”实验的输出进行了比较。我们在模型中调查了气候气候对粉尘排放的作用，并分析了大干旱期间模拟粉尘与其他年份相比的情况。我们发现，裸露的土地是由植被覆盖密度直接调节而由水文气候间接调节的，是西南地区模拟扬尘排放的主要控制手段。此外，与模型中没有大干旱的年份相比，大干旱期间的粉尘排放量略高（但显着）。使用简单的前向建模方法评估年龄不确定性在区域沙尘记录中的影响，我们发现年龄不确定性可以解释大多数古数据/模型分歧。其余的差异可能与模型中未包含的抑制干旱期间扬尘排放的过程有关，这些过程包括棕色植被和土壤结皮。我们的研究结果表明，尘埃干旱关系是一个连续的过程，干旱对尘埃循环的影响是微妙的。使用简单的前向建模方法评估年龄不确定性在区域沙尘记录中的影响，我们发现年龄不确定性可以解释大多数古数据/模型分歧。其余的差异可能与模型中未包含的抑制干旱期间扬尘排放的过程有关，这些过程包括棕色植被和土壤结皮。我们的研究结果表明，尘埃干旱关系是一个连续的过程，干旱对尘埃循环的影响是微妙的。使用简单的前向建模方法评估年龄不确定性在区域沙尘记录中的影响，我们发现年龄不确定性可以解释大多数古数据/模型分歧。其余的差异可能与模型中未包含的抑制干旱期间扬尘排放的过程有关，这些过程包括棕色植被和土壤结皮。我们的研究结果表明，尘埃干旱关系是一个连续的过程，干旱对尘埃循环的影响是微妙的。