Collaborative Research: Quantifying the Role of Pollen in Cloud Formation through Measurements and Modeling

虽然植物从地球表面大量排放花粉，但由于花粉颗粒的大尺寸，这些排放物通常被排除在清单之外。然而，最近的研究表明，花粉粒在潮湿时容易破裂，形成较小的亚花粉颗粒（SPP）；这些SPP还没有得到很好的研究。本研究的中心目标是准确地确定花粉破裂产生的SPP量，并确定其云形成特性。本研究将包括一系列利用植物室和大气模型模拟的实验。实验室测量将(1)量化大气条件下单个花粉粒和植物发出的SPP的数量，(2)确定云凝结核（CCN）激活所需的过饱和度，以及(3)确定冰成核颗粒（INP）激活所需的温度和相对湿度。这些结果将为在线花粉排放模型提供关键输入，该模型将与天气研究与预报模型和化学模型（WRF-Chem）一起使用，以：(1)实现WRF-Chem中的花粉排放破裂机制，(2)利用测量的破裂数据来改进花粉破裂的模拟，以及(3)利用CCN和INP激活测量进行新的模拟，以解释冷暖云的间接影响。这个跨学科项目使用实验室和建模组件来最大化测量的价值，以改进花粉对云形成影响的模型估计。这项工作还将整合到一门本科课程中，该课程将介绍花粉取样设备，并指导学生了解气溶胶和气候建模的基础知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

While pollen is emitted from the Earth's surface in large quantities from vegetation, these emissions are typically excluded from inventories due to the large size of pollen grains. However, recent studies have shown that pollen grains easily rupture when wet, forming smaller sub pollen particles (SPP); these SPP have not been well-studied. The central goal of this study is to accurately establish the amount of SPP produced by pollen rupture and to determine its cloud formation properties.This study will include a series of experiments utilizing a plant chamber and atmospheric modeling simulations. The laboratory measurements will (1) Quantify the number of SPP emitted from a single pollen grain and from a plant under atmospheric conditions, (2) Determine the supersaturation required for cloud condensation nuclei (CCN) activation, and (3) Determine the temperatures and relative humidities required for ice nucleating particles (INP) activation. These results will provide critical input for an online pollen emissions model that will be used with the Weather Research and Forecasting model coupled with Chemistry model (WRF-Chem) to (1) Implement the pollen emission rupture mechanism in WRF-Chem, (2) Utilize measured rupture data to improve simulations of pollen rupture, and (3) Conduct new simulations that account for the indirect effects from both warm and cold clouds using CCN and INP activation measurements.This interdisciplinary project uses laboratory and modeling components to maximize the value of the measurements for improving model estimates of pollen effects on cloud formation. The work will also be integrated in an undergraduate course that will introduce pollen sampling equipment and instruct students on the basics of aerosol and climate modeling.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.