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

气溶胶与气候的相互作用：扬尘模型的开发和测试

• 批准号: 0622539
• 负责人: Nilton Renno
• 金额: --
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0622539&HistoricalAwards=false
• 关键词: Aerosols; Climate; Interactions; Development; Tests

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.

气溶胶通过散射和吸收太阳和红外辐射产生直接辐射强迫，通过改变云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，了解气溶胶对气候的影响是极其重要的。了解自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很重要。最近发现的证据表明，粉尘带电和由此产生的电动力在扬尘过程中发挥着重要作用。这一气溶胶-气候问题正在通过开发一个基于物理的扬尘模型来解决，并利用它来研究电力对规则的风吹跳跃、沙尘暴以及对流羽流和漩涡所产生的扬尘和输送的影响。该模型首次包含了粉尘带电和电力对扬尘的潜在重要影响。该模型将在开发和测试后立即提供给科学界。在所有类型的自然扬尘过程中，如风吹跳跃、沙尘暴和对流涡旋，都测量到了高达100-200千伏/米的电场。实验室研究表明，这些电场可以直接将土壤颗粒从表面上抬起。计算表明，这些电场可以极大地降低启动跃迁所需的门槛风速。跳跃是较大的沙粒被风移动并在表面反弹，将较小的尘埃粒子抛入空气中的过程。静电效应可能会增强这一过程。它们正在现场和实验室环境中进行测量。这些观测结果构成了在天气和气候模拟模式的对流羽流和涡旋扬尘和输送的参数化中包括静电效应的基础。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造气溶胶的输送。这项研究对科学和社会产生了几个更广泛的影响。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，扬尘模型和尘埃通量参数化将提供给科学界，供在各种建模环境中使用。正在开发一个教育网站，对对流羽流、沙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上的天气现象。它将扩展到包括跳跃、尘埃带电和电力对扬尘的影响的解释。最后，本研究项目将为研究生的培养做出贡献。