The Impact of Fire on Entrainment and Precipitation Efficiency Derived from Isotope Ratios

非洲中部和南部的生物质燃烧产生了一些世界上密度最大的烟层。烟雾羽状并在南大西洋上空传输，在那里它们与大片低海拔层积云融合在一起。关于烟雾气溶胶粒子和层积云如何相互作用的细节还没有得到充分的了解，尽管这些类型的云在当地和全球气候中发挥着不成比例的巨大作用。该项目旨在提高对烟雾如何改变云附近空气循环方式的理解，污染云中的云滴如何以不同于原始云中的速度蒸发，以及当烟雾存在时，毛毛雨是如何改变的。将通过纳米比亚附近的烟雾和云层测量飞机飞行过程中水蒸气和云液中稳定的氧和氢同位素比率，以评估大气混合、云蒸发和云滴生长产生降雨的比例。这些特征很难用更传统的方法来量化。同位素数据将被用来评估NCAR共同体地球系统模型模拟的夹带和蒸发，以评估从实验中获得的新理解在哪里可以改进模型模拟。由于缺乏云-烟相互作用的知识，导致对气候模式中的过程的粗暴处理，从而导致气候模式模拟中的重大不确定性。这项同位素研究为云在模型中的描述方式提供了迫切需要的关键检查，并就哪些机制被错误地表示提供了具体指导。收集的数据集使几个研究小组能够使用同位素约束来测试和比较他们的模型，这将成为实验的宝贵遗产。数据模型合成促进了观察和建模专家之间的合作，并使学生能够接受培训，将建模和数据方法方面的专业知识结合起来，通过合成获得更多的知识。该项目通过将研究经验融入俄勒冈州立大学的课堂教学和公共外联论坛，提供了在多个层面上进行学习的机会。

Biomass burning in central and southern Africa produces some of the world's most dense layers of smoke. The smoke plumes and transported over the southern Atlantic Ocean where they merge with wide areas of low altitude stratocumulus clouds. The details of how smoke aerosol particles and stratocumulus clouds interact is inadequately understood, despite the disproportionally large role those types of clouds play in local and global climate. This project seeks to improve understanding of how smoke changes the way air circulates near clouds, how cloud droplets in polluted clouds evaporate at different rates from those in pristine clouds, and how drizzle is modified when smoke is present. Stable isotope ratios of oxygen and hydrogen in water vapor and cloud liquid will be measured from aircraft flights though smoke and cloud layers near Namibia to evaluate characteristics of atmospheric mixing, cloud evaporation and the fraction of clouds droplets which grow to produce rain. These characteristics are difficult to quantify from more traditional methods. Isotopic data will be used to evaluate entrainment and evaporation simulated by the NCAR Community Earth System Model to evaluate where new understanding from the experiment can improve model simulations. Lack of knowledge about cloud-smoke interactions leads to crude treatment of processes in climate models, which consequently leads important unresolved uncertainties in climate model simulations. The isotopic study provides a sorely needed critical check on how clouds are depicted in models and gives specific guidance as to which mechanisms are incorrectly represented. The datasets collected enable several research groups to test and compare their models using isotopic constraints which will serve as a valuable legacy of the experiment. The data-model synthesis fosters collaboration that bridges between observation and modeling specialists and enables students training in combining expertise in modeling and data methods to achieve enhanced knowledge though synthesis. The project provides opportunities to engage learning at many levels though incorporation of research experiences in class room teaching at Oregon State University and in public outreach forums.