Collaborative Research: Contrasting the Effects of Aerosols on Marine Boundary Layer (MBL) Cloud-precipitation Properties and Processes in Boreal and Austral Mid-latitude Regions

该项目旨在调查海洋边界层云的形成，这是直接受海洋影响的云。特别是，微小的悬浮颗粒或气溶胶如何对云起作用，以及云如何与气溶胶相互作用。气溶胶是由大气、陆地和海洋过程产生的，如城市/工业活动、沙尘暴、燃烧的植被、生物活动、海浪、风流和火山。某些气溶胶类型比其他类型更容易引发海洋边界层云的发展。这增加了海洋边界层云对天气变化影响的复杂性和不确定性。海洋边界层云对水文循环和地球辐射平衡具有重大的气候影响。例如，海洋边界层云在地球仪上的分布各不相同，造成了太阳能和降雨量不足和过剩的地区。在全球人口和陆地分布最多的北方半球，人们对气溶胶-云相互作用进行了许多研究。对南半球广大的偏远陆地和海洋地区知之甚少。本研究将借由分析最近的野外观测资料及利用数值模式模拟来探讨北方与南半球间气溶胶-云相互作用的差异与相似性。该项目吸引本科生和研究生参与研究项目，并将他们培养成为下一代科学家。该研究采用了北大西洋东部专用观测站的长期地基观测和遥感检索，以及飞机现场测量2018年两次密集的实地活动：1）北大西洋东部气溶胶和云实验（ACE-ENA），和2）南大洋云，辐射，气溶胶传输实验研究（SOCRATES）。该研究小组利用协同测量/建模方法结合气象模式，通过回答三个科学问题来比较两个半球海洋边界层气溶胶，云和毛毛雨特性的特征。这些原则是：1）在海洋边界层上空气溶胶-云相互作用和暖雨过程中，地面云凝结核和上升气流的相对作用是什么？2)海洋边界层气溶胶、云和毛毛雨的特性及其在两次实地活动中的相互作用有何特点？3)海洋边界层气溶胶、云和毛毛雨的特性，它们在南大洋上空的相互作用，以及它们与北大西洋东部的相似性和不同性是什么？通过对两个具有显著不同环境条件的站点的降水过程和气溶胶-云相互作用的比较，将揭示气溶胶-云相互作用的控制因素，并最终导致气溶胶的广义参数化。该奖项反映了美国国家科学基金会的法定使命，并被认为是值得通过使用基金会的智力价值进行评估来支持的和更广泛的影响审查标准。

The project is to investigate formation of marine-boundary-layer clouds, which are clouds that are directly influenced by the ocean. Particularly, how tiny suspended particles or aerosols contribute to clouds and how clouds interact with aerosols. Aerosols are generated from atmospheric, land, and oceanic processes such as urban/industrial activity, dust storms, burning vegetation, biological activity, sea spray, wind currents, and volcanoes. Certain aerosol types can initiate marine-boundary-layer cloud development more easily than others. This adds to the complexity and uncertainty of marine-boundary-layer cloud impacts on weather variations. Marine-boundary-layer clouds have significant climatological effects on the hydrological cycle and the Earth’s radiation balance. For example, varying distributions of marine-boundary-layer clouds around the globe contribute to areas of deficits and surpluses in solar energy and rainfall. Many studies have been conducted on aerosol-cloud interactions in the Northern Hemisphere where most of the global population and landmasses are located. Not much is known over the vast area of remote land and oceanic regions in the Southern Hemisphere. This study will investigate differences and similarities of aerosol-cloud interactions between the Northern and Southern Hemispheres by analyzing recent field observations and utilizing numerical model simulations. The project involves undergraduate and graduate students to participate in the research project and train them to be the next generation of scientists.This study employs long-term ground-based observations and remote sensing retrievals from a dedicated observation site in the Eastern North Atlantic Ocean and aircraft in situ measurements from two intensive field campaigns in 2018: 1) the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA), and 2) the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES). The research team utilizes a synergistic measurement/modeling approach in conjunction with meteorological patterns to compare the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties over the two hemispheres through answering three scientific questions. Those are: 1) what are the relative roles of surface cloud condensation nuclei and updrafts in aerosol-cloud interactions over the marine boundary layer and warm rain processes? 2) what are the characteristics of marine-boundary-layer aerosol, cloud and drizzle properties and their interactions during two field campaigns? 3) what are the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties, their interactions over the Southern Ocean, and their similarities and differences compared with those in the Eastern North Atlantic Ocean? Comparisons of precipitation processes and aerosol-cloud interactions at the two sites with significantly different environmental conditions will shed light on the controlling factors in aerosol-cloud interactions and eventually lead to a generalized parameterization for aerosol-cloud interactions applicable for the global climate models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.