CAREER: Toward Improved Parameterizations of Brown Carbon in Wildland-Fire Emissions

这个CAREER项目将促进对野火排放的棕色碳（BrC）的光吸收特性的理解。BrC的光吸收特性变化超过3个数量级，这对在气候模型中代表BrC构成了重大挑战。将制定一个光学分布框架，通过考虑BrC光吸收特性的变化及其在大气中光化学老化后的演变，提高BrC在气候计算中的代表性。本研究的主要任务是：（1）模拟美国林务局的野外火灾;（2）反演BrC的光吸收特性;（3）研究BrC的光吸收特性;（4）研究BrC在大气中的分布特征;（5）研究BrC在大气中的分布特征（光学分布）;（3）参数化开发;（4）化学传输和辐射传输建模。将进行生物质燃烧实验，模拟野火和规定的火灾，并将调查燃料类型、燃烧技术和水分含量等关键变量对排放情况的影响。三个密集的测量活动将在新建的美国林务中心森林干扰科学燃烧设施。BC和BrC的排放因子，以及它们的光学分布，将来自这些实验和参数化的火灾辐射功率（FRP），燃烧条件的代理的函数。该框架的新奇在于利用BrC的物理化学和光学性质之间的相关性来检索光学分布。通过这些研究制定的参数化方法将把测量活动的结果与遥感观测结果联合收割机结合起来。这些参数化将在WRF-Chem中实现，这是一个耦合的化学传输和气候模式。该项目还包括一个独特的跨学科教育部分，涉及开发一门课程，将格鲁吉亚大学工程专业的学生与城市设计专业的学生联系起来，参加区域规划课程。该奖项反映了NSF的法定使命，并被认为值得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来支持。

This CAREER project will advance the understanding of the light-absorption properties of brown carbon (BrC) emitted from wildfires. The light-absorption properties of BrC vary over 3 orders of magnitude, posing major challenges to representing BrC in climate models. An optical distributions framework will be developed to enhance the representation of BrC in climate calculations by accounting for the variability in BrC light-absorption properties and their evolution upon photochemical aging in the atmosphere. This research could make a major contribution to improving the understanding of the role of BrC in earth's climate system.The tasks to be conducted as part of this research are as follows: (1) Simulating wildland fires at the U.S. Forest Service facility; (2) Retrieval of BrC light-absorption properties (optical distributions); (3) Parameterization development; and (4) Chemical transport and radiative-transfer modeling. Biomass combustion experiments will be conducted that simulate wildfires and prescribed fires, and the effects of critical variables such as fuel type, firing techniques, and moisture content on emission profiles will be investigated. Three intensive measurement campaigns will be conducted at the newly built U.S. Forest Service Center for Forest Disturbance Science combustion facility. The BC and BrC emission factors, and their optical distributions, will be derived from these experiments and parameterized as a function of fire radiative power (FRP), a proxy of combustion conditions. The novelty of the framework lies in the utilization of correlations between BrC physicochemical and optical properties to retrieve optical distributions. The parameterizations developed through these studies will combine findings from the measurement campaigns with remote-sensing observations. The parameterizations then will be implemented in WRF-Chem, a coupled chemical-transport and climate model.Both graduate and undergraduate students will receive training through this effort. The project also includes a unique cross-disciplinary education component that involves developing a course that would link University of Georgia engineering students with urban design students taking a regional planning course.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.