Aerosols-Climate Interactions: Development and Tests of a Dust Lifting Model

气溶胶通过散射和吸收太阳辐射和红外辐射产生直接辐射强迫，通过改变云的过程产生间接辐射强迫。由于人类活动导致大气气溶胶浓度显著增加，因此了解气溶胶对气候的影响极为重要。了解天然气溶胶的作用以及它们如何受到人类的影响对于量化气溶胶对气候的辐射强迫非常重要。最近发现的证据表明，粉尘带电和由此产生的电力起着重要的作用，粉尘提升。这一气溶胶-气候问题的解决方法是开发一个基于物理的粉尘抬升模型，并利用该模型研究电力对粉尘抬升和通过常规风吹跃移、沙尘暴以及对流羽流和涡旋进行的输送的影响。该模型是第一个包括粉尘带电和电力对粉尘提升的潜在重要影响。该模型一经开发和测试，将立即提供给科学界，在所有类型的自然尘埃上升过程中，如风吹跃移、沙尘暴和对流涡旋中，测得的电场高达100-200千伏/米。实验室研究表明，这些电场可以直接将土壤颗粒从表面提起。计算表明，这些电场可以大大降低起动跃移所需的临界风速。跃移是较大的沙粒被风移动并在表面反弹的过程，将较小的灰尘颗粒喷射到空气中。静电效应可以增强这一过程。目前正在实地和实验室环境中对这些指标进行测量。这些观测结果构成了将静电效应纳入天气和气候模拟模式中对流羽流和涡旋引起的沙尘抬升和输送参数化的基础。这种尘埃通量参数化包括从大气表层到对流层顶部的自然和人为气溶胶的传输。这项研究对科学和社会产生了广泛的影响。除了研究对我们理解全球气候变化至关重要的一个重要科学问题外，科学界还可以在各种建模环境中使用沙尘抬升模型和沙尘通量参数化。正在开发一个教育网站，对对流羽流、尘暴和沙尘暴的形成进行简单的物理解释。这个网站比较了地球和其他行星的天气现象。它将扩大到包括跳跃的解释，粉尘带电，和电力对粉尘升降的影响。最后，本研究计画将有助于研究生的培养。

Aerosols produce direct radiative forcing by scattering and absorbing solar and infrared radiation, and indirect radiative forcing by altering cloud processes. Since human activity has been causing significant increases in the concentration of atmospheric aerosols, it is extremely important to understand the effects of aerosols on climate. Understanding the role of natural aerosols and how they are influenced by humans is important to the quantification of aerosols' radiative forcing on climate. Recently found evidence suggests that dust electrification and the resulting electrical forces play an important role on dust lifting. This aerosol-climate problem is being addressed by developing a physically-based dust lifting model and using it to study the effects of electric forces on dust lifting and transport by regular wind-blown saltation, dust storms, and convective plumes and vortices. The model is the first to include dust electrification and the potentially important effects of electric forces on dust lifting. The model will be made available to the scientific community as soon as it is developed and tested.Electric fields as high as 100-200 kV/m have been measured in all types of natural dust lifting processes such as wind-blown saltation, dust storms and convective vortices. Laboratory research shows that these electric fields can directly lift soil particles from the surface. Calculations show that these electric fields can greatly reduce the threshold wind speed necessary to initiate saltation. Saltation is the process by which larger sand particles are moved by the wind and bounce on the surface, ejecting smaller dust particles into the air. Electrostatic effects may enhance this process. They are being measured in field and laboratory settings. These observations form the basis for including electrostatic effects in a parameterization for the dust lifting and transport by convective plumes and vortices in weather and climate simulation models. This dust flux parameterization includes the transport of both natural and man-made aerosols from the atmospheric surface layer up to the top of the convective layer.The research has several broader impacts on science and society. Besides studying an important scientific problem key to our understanding of global climate change, the dust lifting model and dust flux parameterization will be available to the scientific community for use in a wide variety of modeling contexts. An educational website is being developed with simple physical explanations of the formation of convective plumes, dust devils, and dust storms. This website compares weather phenomena on Earth and other planets. It will be expanded to include explanations of saltation, dust electrification, and the effects of electric forces on dust lifting. Finally, this research project will contribute to the training of a graduate student.