Constraining the Direct Radiative Forcing of Desert Dust

沙漠尘埃约占大气中颗粒物总质量的三分之二。灰尘如此丰富的原因之一是，自工业革命以来，灰尘数量大幅增加，甚至可能翻了一番。这种大幅增长可能是由于人类活动，如为农业清理土地。令人惊讶的是，越来越多的沙漠尘埃对气候系统的影响仍然是个谜。事实上，历史上尘埃的增加是促成了还是抵消了气候系统的温室气体变暖，这仍然是一个悬而未决的问题。这个项目将通过以下方式回答这个问题：(i)确定尘埃对太阳和地面辐射的散射和吸收所产生的地球能量收支的变化，（ii）确定自工业革命以来尘埃增加的数量，以及（iii）确定尘埃增加所导致的地球能量收支的变化。这些目标将通过结合卫星观测、飞机测量、世界各地沙漠尘埃沉积变化的大量记录以及尘埃如何影响地球辐射收支的数值模拟来实现。这项研究将由一个由本科生、研究生和一名博士后学者组成的科学家团队进行。确定历史上沙漠沙尘增加对气候的影响是很重要的，因为计算气候系统对温室效应变暖有多敏感，取决于沙尘等颗粒物质产生的降温作用在多大程度上抵消了温室效应变暖。因此，该项目将更准确地预测未来温室气体增加所造成的气候变化，这对于有效地应对这些变化至关重要。该项目还将继续在洛杉矶地区服务不足的高中开展成功的外展项目。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Desert dust accounts for about two thirds of the total mass of particulate matter in our atmosphere. One of the reasons that dust is so abundant is that it has increased substantially, perhaps even doubled, since the Industrial Revolution. This large increase is probably because of human actions like clearing land for agriculture. Surprisingly, the impact of the increasing desert dust on the climate system has remained mysterious. In fact, it is still an open question whether this historical increase in dust has contributed to or counteracted greenhouse gas warming of the climate system. This project will answer this question by (i) determining the change in Earth’s energy budget produced by the scattering and absorbing of solar and terrestrial radiation by dust, (ii) determining the amount by which dust has increased since the Industrial Revolution, and (iii) determining the resultant change in Earth’s energy budget from the increase in dust. These goals will be achieved by combining satellite observations, aircraft measurements, numerous records of how deposition of desert dust has changed across the world, and numerical simulations of how dust affects Earth’s radiation budget. The research will be performed by a team of scientists that include undergraduate and graduate students and a postdoctoral scholar.Determining the climate impact of the historical increase in desert dust is important because calculations of how sensitive the climate system is to greenhouse warming depend on the extent to which greenhouse warming has been counteracted by cooling produced by particulate matter like dust. This project will thus result in more accurate predictions of the climate changes produced by future increases in greenhouse gases, which is critical to an effective societal response to those changes. The project will also continue a successful outreach project to under-served high schools in the Los Angeles area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.