Interactions of Aerosols, Marine Boundary Layer Clouds, and Precipitation During the VOCALS-Regional Experiment: Observations, Modeling, and Large-scale Model Assessment

VOCALS 区域实验期间气溶胶、海洋边界层云和降水的相互作用：观测、建模和大型模型评估

• 批准号: 1242639
• 负责人: Robert Wood
• 金额: $ 53.19万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-11-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1242639&HistoricalAwards=false
• 关键词: Interactions; Aerosols; Marine; Boundary; Layer

This supports analysis of collected during the Variability of the American Monsoon Systems Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx, or simply REx). The VOCALS-REx field campaign took place over the Southeast Pacific Ocean (SEP) during Oct-Nov 2008, and was designed to improve understanding of interactions between aerosols, marine boundary layer (MBL) clouds, and precipitation over the region. The SEP is climatically important because it is home to the world's largest subtropical stratocumulus cloud deck, which cools the climate by reflecting solar radiation back to space. Thus interactions between clouds, aerosols, and precipitation in the SEP can have an important climatic effect by modulating cloud cover and cloud albedo. The research here continues two key REx themes: research on Pockets of Open Cells (POCs), which are openings in the stratocumulus deck in which clouds have presumably dissipated due to drizzle formation; and research on offshore transport of pollution and its effect on SEP cloud and aerosol characteristics. Observations of cloud droplet concentration taken during REx using the NCAR C-130 aircraft show large "hook" features extending offshore from the Chilean coast, which may be due to high concentrations of cloud condensation nuclei (CCN) associated with pollution from copper smelters and coastal conurbations.Research performed under this grant uses REx data, much of which has not been previously analyzed, as well as data from global atmospheric model simulations prepared for the VOCALS Model Assessment (VOCA), together with numerical experiments using a large-eddy simulation (LES) code, to develop a better understanding of POCs, hooks, and SEP aerosol-cloud interactions. Three broad science questions are addressed: 1) How important is the free-tropospheric aerosol source to CCN and cloud droplet number concentrations in the VOCALS region, especially in the oceanic region over 500 km away from coastal pollution sources? 2) Is the precipitation sink for aerosols a major positive feedback on CCN differences between clean and polluted regions, in particular for hooks and POCs? 3) Can regional and global chemistry-climate models that include some representation of aerosol-cloud- precipitation interactions realistically simulate hooks and POCs?Beyond its scientific merit, the project has broader impacts due to the important role of SEP clouds in regulating earth's climate. A better understanding of the role of aerosol-cloud interactions in determining cloud cover and cloud brightness could thus lead to improved understanding and predictions of climate variability and change. In addition, the project supports two graduate students, thereby providing for the next generation of the scientific workforce in this area.

这支持了在美国季风系统海洋-云-大气-陆地研究区域实验(Voals-Rex，或简称Rex)期间收集的可变性分析。SOVALS-REX现场活动于2008年10月至11月在东南太平洋(SEP)上空进行，旨在增进对该地区气溶胶、海洋边界层云和降水之间相互作用的了解。SEP在气候上很重要，因为它是世界上最大的副热带平流层积云的所在地，它通过将太阳辐射反射回太空来冷却气候。因此，SEP中云、气溶胶和降水之间的相互作用可以通过调节云量和云反照率来产生重要的气候效应。这里的研究继续了两个关键的REX主题：开放单元格(POCs)口袋的研究，这是层积云甲板上的开口，据推测其中的云已经因细雨形成而消散；以及关于污染的近海输送及其对SEP云和气溶胶特征的影响的研究。使用NCARC C-130飞机对REX期间的云滴浓度进行的观测显示，从智利海岸近海延伸出来的大“钩状”特征可能是由于与铜冶炼厂和沿海城市的污染有关的云凝结核(CCN)的高浓度所致。根据这项赠款开展的研究使用了REX数据，其中许多数据以前从未被分析过，以及为Voals模式评估(VOCA)准备的全球大气模式模拟数据，以及使用大涡模拟(LES)代码的数值实验，以更好地了解POCs、挂钩和SEP气溶胶-云相互作用。讨论了三个广泛的科学问题：1)自由对流层气溶胶源对CCN和声区云滴数量浓度的重要性有多大，特别是在距离沿海污染源500公里以上的海洋区域？2)气溶胶的降水汇是清洁区域和污染区域之间CCN差异的主要正反馈，特别是对于钩子和POC？3)区域和全球化学-气候模式是否能够真实地模拟钩子和POC？除了其科学价值之外，该项目还具有更广泛的影响，因为SEP云在调节地球气候方面发挥了重要作用。因此，更好地了解气溶胶-云相互作用在确定云量和云亮度方面的作用，可以改进对气候变异性和变化的理解和预测。此外，该项目还支持两名研究生，从而为这一领域的下一代科学工作者提供支持。