Converting AOT to CCN for Studying the Impact of Aerosol on Cloud and Precipitation

将 AOT 转换为 CCN 以研究气溶胶对云和降水的影响

• 批准号: 1118325
• 负责人: Zhanqing Li
• 金额: $ 45万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1118325&HistoricalAwards=false
• 关键词: Converting; AOT; CCN; Studying; Impact

Aerosols affect the climate system by changing cloud characteristics in many ways and with a high degree of uncertainty. Using 10 years' worth of Atmospheric Radiation Measurement (ARM) ground-based measurements of a variety of aerosol and meteorological quantities at the Southern Great Plains (SGP) site, robust relationships were found between aerosol concentration, cloud height and rain frequency. To extend the study from a single location with limited types of aerosols, we will analyze world-wide surface Aerosol Robotic Network (AERONET) aerosol data, together with matched satellite-retrieved cloud and precipitation products, to further investigate the impact of all kinds of aerosols and meteorological conditions on clouds and precipitation. While the AERONET provides the most reliable and consistent retrievals of aerosol optical thickness (AOT), it is cloud concentration nuclei (CCN) that is more directly related to cloud formation, development and precipitation. Many previous studies used AOT as a proxy for CCN, because there are much more observations of AOT than those of CCN. These two quantities describe different aerosol attributes so a thorough understanding of their relationship is warranted, which is lacking at present.The objectives of this research are to:1) investigate factors that influence the relationship between AOT and CCN, such as ambient relative humidity (RH), the particle size distribution and hygroscopic properties of aerosol particles;2) develop more robust AOT-CCN relationships by accounting for major influencing factors and apply them to AERONET AOT data to obtain better estimates of CCN at AERONET sites;3) match estimated CCN data with satellite cloud and precipitation data from CloudSat to study the impact of aerosols on cloud and precipitation.The study will make use of extensive measurements from AERONET, field experiments, and satellite missions. Tasks 1 and 2 will rely on measurements of aerosol properties, ambient meteorological conditions and CCN collected in field campaigns conducted in many parts of the world. Numerous factors will be examined, such as air mass, particle size distribution, soluble fraction, etc., and their influences on both optical and hygroscopic properties of aerosols will be assessed. Intellectual merit:1) A comprehensive analysis of how AOT and CCN are affected by aerosol properties and the ambient environment that have been most widely employed for studying aerosol radiative and microphysical effects;2) The improved relationship between AOT and CCN will enable the extension of widely available AOT from ground-based and space-borne sensors to study the impact of aerosols on cloud and precipitation, as many have done but without rigorous investigation of their relationship;3) Further investigation and understanding of the impact of aerosols on cloud and precipitation on global scales for different types of aerosols under diverse meteorological conditions.Broad impacts:1) With an improved knowledge and understanding of the AOT-CCN relationship, modelers would be better informed and motivated to explore the use of global satellite AOT products to fill the void currently present in studying the impacts of aerosols on global climate;2) The research will provide interdisciplinary training opportunities in measuring aerosols, data analysis, and modeling for undergraduate and graduate students and postdoctoral fellows;3) This study will have an immediate impact on the teaching of cloud physics, atmospheric chemistry, climate and environmental courses.

气溶胶通过以多种方式改变云的特性来影响气候系统，并且具有高度的不确定性。 使用10年的大气辐射测量（ARM）的各种气溶胶和气象量在南部大平原（SGP）网站的地面测量值，气溶胶浓度，云高和降雨频率之间的关系被发现。 为了将研究从具有有限类型气溶胶的单一位置扩展，我们将分析全球地面气溶胶机器人网络（AERONET）气溶胶数据，以及匹配的卫星检索的云和降水产品，以进一步调查各种气溶胶和气象条件对云和降水的影响。 虽然AERONET提供了最可靠和一致的气溶胶光学厚度（AOT）反演，但云浓度核（CCN）与云的形成，发展和降水更直接相关。 由于AOT的观测数据比CCN的观测数据多得多，因此以往的许多研究都将AOT作为CCN的替代。 本研究的主要目的是：1）研究影响AOT与CCN关系的因素，如环境相对湿度、气溶胶粒子的粒径分布和吸湿特性等; 2）开发更强大的AOT-计算主要影响因素的云凝结核关系，并将其应用于AERONET AOT数据，以获得AERONET站点云凝结核的更好估计; 3）将估算的云凝结核数据与CloudSat卫星的云和降水数据进行匹配，研究气溶胶对云和降水的影响。研究将利用AERONET、现场试验和卫星任务的广泛测量。任务1和任务2将依赖于在世界许多地方开展的实地活动中收集的气溶胶特性、环境气象条件和云凝结核的测量结果。 将检查许多因素，如空气质量、粒度分布、可溶性分数等，并评估它们对气溶胶光学和吸湿特性的影响。 知识价值：1）全面分析气溶胶特性和周围环境如何影响气溶胶光学厚度和云凝结核，气溶胶特性和周围环境是研究气溶胶辐射和微物理效应最广泛采用的;2）改进气溶胶光学厚度和云凝结核之间的关系将使广泛使用的陆基和星载传感器气溶胶光学厚度能够扩展到研究气溶胶对云和降水的影响，许多人已经这样做，但没有严格调查它们之间的关系; 3）进一步研究和理解不同气象条件下不同类型气溶胶对全球尺度云和降水的影响。广泛的影响：1）随着对AOT-CCN关系的认识和理解的提高，模式工作者将更好地了解和激励探索使用全球卫星AOT产品来填补目前在研究气溶胶对全球气候影响方面存在的空白; 2）这项研究将为本科生、研究生和博士后研究员提供测量气溶胶、数据分析和建模方面的跨学科培训机会;3）这项研究将对云物理学、大气化学、气候和环境课程的教学产生直接影响。