Toward Improved Understanding of Fundamental Processes Controlling the Size-Resolved Properties of Particles in the Stratosphere

在这个研究项目中，PI将研究控制平流层气溶胶的物理和化学过程，这将提高我们描述和理解与火山排放及其产生的气候和化学影响相关的现象的能力。显然需要更好地了解平流层气溶胶的过程，这项工作将填补与平流层新粒子形成有关的现有数据空白。具体而言，这项工作需要解决的三个数据差距是：（1）控制平流层新粒子形成的关键参数是什么，现有对流层模型在多大程度上可扩展到平流层条件？(2)导致观测到的气溶胶特性未被现有模式捕获的潜在微物理和传输过程是什么？(3)在重大火山爆发后，模型模拟的平流层气溶胶寿命短于观测值，对此可能有哪些解释？这些数据差距将通过以下任务加以解决。首先，将研究平流层中粒子成核的新机制。其次，将研究导致在平流层积累模式粒子中观察到的双峰结构的过程，这些过程目前没有被模型捕获。第三，将研究在目前的模型中，火山后硫酸盐质量负荷减少速度比观察到的要快的潜在原因。结果和新的参数化将通过广泛使用的GEOS-Chem模型中的高级粒子微观物理模型来实现。该项目将支持和培训一名博士后研究员、一名研究生和一名本科生，并为代表性不足的高中高年级学生提供研究经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this research project, the PI will study the physical and chemical processes that control stratospheric aerosols which will advance our ability to characterize and understand phenomena associated with volcanic emissions and their resultant climate and chemistry impacts. There is a clear need to better understand stratospheric aerosol processes and this work will address existing data gaps related to new particle formation in the stratosphere. Specifically, the three data gaps to be addressed in this work are: (1) What are the key parameters that control new particle formation in the stratosphere and how extendible are the existing tropospheric models to stratospheric conditions? (2) What are the underlying microphysical and transport processes that lead to the observed aerosol properties that are not captured by existing models? (3) What are possible explanations for the shorter-than-observed model simulated stratospheric aerosol lifetime after major volcanic eruptions? These data gaps will be addressed via the following tasks. First, new mechanisms of particle nucleation in the stratosphere will be developed. Second, the processes which lead to the observed bimodal structure in accumulation mode particles in the stratosphere that are currently not captured in models will be studied. Third, potential reasons for faster-than-observed reductions in post-volcanic sulfate mass burdens in current models will be examined. The results and new parameterizations will be implemented via an Advanced Particle Microphysics model within the widely used GEOS-Chem model. This project will support and train a postdoctoral researcher, a graduate, and an undergraduate student, plus provide research experience for underrepresented high school senior students.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.