Collaborative Research: Inhibition of Snowfall by Pollution Aerosols

合作研究：污染气溶胶抑制降雪

• 批准号: 0451374
• 负责人: Randolph Borys
• 金额: $ 51.4万
• 依托单位: Nevada System of Higher Education, Desert Research Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-11-15 至 2009-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0451374&HistoricalAwards=false
• 关键词: Collaborative; Research; Inhibition; Snowfall; Pollution

This is a collaborative project to study the effect of air pollution on snowfall rates and amounts. Previous work by two of the investigators (Borys and Lowenthal) developed evidence suggesting that the particles in polluted air decrease snowfall rates and amounts. The mechanism, not fully documented but clearly suggested by earlier work, is that the higher particle concentrations associated with air pollution contain increased numbers of cloud condensation nuclei (CCN), the particles on which cloud droplets form. Pollution thus increases the concentration of cloud droplets but decreases their average size, and so decreases the efficiency with which falling ice crystals grow by collision with the supercooled droplets. Pollution therefore reduces precipitation by reducing the amount of supercooled water collected from clouds and deposited in snowfall. The study will take additional steps toward determining how snowfall from winter orographic clouds, observed at the Desert Research Institute's Storm Peak Laboratory, is reduced by the high concentration of aerosol particles associated with pollution. This extension of previous work will include direct measurement of the CCN, continued observations of snowfall and precipitation, and modeling to establish the physical links between pollution and snowfall amount. The project will use a mesoscale model that has demonstrated skill in predicting precipitation rates and amounts. Key objectives are these:* To determine the relationship between pollution-aerosol loading and snowfall rate;* To determine the relative importance of riming, snow crystal size, crystal habit, and large-scale meteorological features in determining the snowfall rate;* To conduct sensitivity studies of effects including the above using the RAMS mesoscale model with bin-emulating microphysics; and* To estimate the quantitative effect of pollution aerosol on snowfall rate and amount in the study region through use of the mesoscale model.The anticipated result is a new ability to predict how air pollution affects snowfall in pristine mountainous areas and so changes the watershed in areas where water resources are critically important. The project should also lead to improved understanding of how to represent the effects of air pollution in models of weather and climate, especially as they influence precipitation.

这是一个合作项目，旨在研究空气污染对降雪率和降雪量的影响。两位研究者（鲍里斯和洛温塔尔）之前的研究表明，污染空气中的颗粒物会降低降雪率和降雪量。这一机制没有被充分记录，但早期的工作清楚地表明，与空气污染有关的较高颗粒浓度含有更多的云凝结核（CCN），云滴形成的颗粒。因此，污染增加了云滴的浓度，但减小了它们的平均大小，从而降低了下落的冰晶与过冷的云滴碰撞时的生长效率。因此，污染减少了从云中收集并沉积在雪中的过冷水的数量，从而减少了降水。这项研究将进一步确定沙漠研究所风暴峰实验室观测到的冬季地形云降雪量是如何被与污染有关的高浓度气溶胶粒子减少的。对以往工作的扩展将包括直接测量CCN，持续观测降雪和降水，以及建立污染和降雪量之间物理联系的建模。该项目将使用一种中尺度模式，该模式在预测降水率和降水量方面已经证明了技巧。主要目标如下：*确定污染气溶胶负荷与降雪率之间的关系；*厘定雾凇、雪晶大小、结晶习性及大尺度气象特征在厘定降雪率时的相对重要性；*利用模拟垃圾箱的RAMS中尺度模式进行包括上述影响在内的敏感性研究；*利用中尺度模式估计污染气溶胶对研究区降雪率和降雪量的定量影响。预期的结果是一种新的能力，可以预测空气污染如何影响原始山区的降雪，从而改变水资源至关重要的地区的分水岭。该项目还应使人们更好地了解如何在天气和气候模式中表示空气污染的影响，特别是当它们影响降水时。