Aerosol Eddy Flux and Hygroscopic Growth During Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX)

该项目的目标是在两个生物圈对气溶胶和光化学实验（BEARPEX）野外活动期间，通过涡流通量和颗粒吸湿性生长来测量颗粒沉积。BEARPEX将在加利福尼亚的黄松森林进行，以检查森林与大气的相互作用；它包括对来自森林排放物的二次有机气溶胶的化学成分、气溶胶吸湿性生长的程度以及沉积到森林冠层的气溶胶量的实验检查。气溶胶大小光谱由粒子浓度的光学测量（0.3 - 2微米直径）组成，使用优化的气溶胶通量测量仪器（FAST），以及来自声波风速计的三维风速数据将在冠层上方的塔上以10赫兹收集。湍流通量将利用涡旋相关（EC）技术从气溶胶浓度和垂直风中确定。另外两个气溶胶光学仪器将在不同的相对湿度下运行，以确定由于吸湿生长而导致的颗粒大小分布的变化。这种测量的吸湿性增长将与基于BEARPEX合作者测量的气溶胶化学成分的增长预测进行比较。该项目将有助于更好地了解气溶胶去除及其对气候变化、污染物暴露和生态系统压力的影响。拟议研究的更广泛影响还包括研究生和本科生教育，并将项目结果纳入大气化学和气溶胶微物理学的课堂材料。

The goal of this project is to measure particle deposition via eddy fluxes and particle hygroscopic growth during the two Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) field campaigns. BEARPEX will be conducted at a ponderosa pine forested site in California to examine forest-atmosphere interactions; it includes an experimental examination of the chemical composition of secondary organic aerosol from forest emissions, the extent of hygroscopic growth of the aerosol, and the amount of aerosol that is deposited to the forest canopy. Aerosol size spectra consisting of optical measurements of particle concentration (0.3 - 2 micron dia.) using an instrument optimized for aerosol flux measurements (FAST), and 3-D wind speed data from a sonic anemometer will be collected from a tower above the canopy at 10 Hz. Turbulent fluxes will be determined from the aerosol concentrations and vertical winds using the eddy correlation (EC) technique. Two additional aerosol optical instruments will be operated at different relative humidities to determine the change in particle size distribution due to hygroscopic growth. This measured hygroscopic growth will be compared to growth predictions based on measured aerosol chemical composition from BEARPEX collaborators. This project should lead to a better understanding of aerosol removal and its impacts on climate change, pollutant exposure, and ecosystem stresses. Broader impacts of the proposed research also include graduate and undergraduate education and incorporation of project results into class materials in atmospheric chemistry and aerosol microphysics.