Observations of Ice Nucleating Particles in the Free Troposphere From Western US Wildfires
Observations of Ice Nucleating Particles in the Free Troposphere From Western US Wildfires
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DOI：
10.1029/2020jd033752
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发表时间：
2021-02-16
影响因子：
4.4
通讯作者：
DeMott, Paul J.
中科院分区：
文献类型：
--
作者：
Barry, Kevin R.;Hill, Thomas C. J.;DeMott, Paul J.
美国西部的野火是颗粒物的主要来源，预计未来野火烧毁的面积还会增加。野火释放的一些颗粒可以通过充当冰成核颗粒（INPs）来影响云的形成。INPs对云辐射特性和降水发展有许多影响。野火是潜在的重要来源的INPs，从以前的测量表明，但其丰富的自由对流层尚未量化。西部野火实验云化学，气溶胶吸收，氮活动采样免费对流层浸没冻结INPs从烟羽附近的来源和顺风，沿着广泛的老烟。结果表明，相对于羽流外背景空气，烟羽流中的INPs增强，但增强的幅度与温度和火灾有关。大多数的INPs被推断为主要是有机的组成与一些贡献，从生物来源在适度的过冷，和矿物的贡献在更深的过冷。火灾涉及主要是山艾灌木丛土地和白杨森林燃料有最高的INP浓度测量的运动，这是部分归因于INP特性的阁楼，未燃烧的植物材料。INPs的电子显微镜分析也表明在这场火灾中存在焦油球。参数化的羽INP数据的每单位气溶胶表面积的基础上证实，烟雾是不是一个有效的源INPs。然而，大量的颗粒释放，无处不在的美国西部野火在夏季，区域性地提高INP浓度在自由对流层。
Wildfires in the western United States are large sources of particulate matter, and the area burned by wildfires is predicted to increase in the future. Some particles released from wildfires can affect cloud formation by serving as ice-nucleating particles (INPs). INPs have numerous impacts on cloud radiative properties and precipitation development. Wildfires are potentially important sources of INPs, as indicated from previous measurements, but their abundance in the free troposphere has not been quantified. The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen campaign sampled free tropospheric immersion-freezing INPs from smoke plumes near their source and downwind, along with widespread aged smoke. The results indicate an enhancement of INPs in smoke plumes relative to out-of-plume background air, but the magnitude of enhancement was both temperature and fire dependent. The majority of INPs were inferred to be predominately organic in composition with some contribution from biological sources at modest super cooling, and contributions from minerals at deeper super cooling. A fire involving primarily sagebrush shrub land and aspen forest fuels had the highest INP concentrations measured in the campaign, which is partially attributed to the INP characteristics of lofted, uncombusted plant material. Electron microscopy analysis of INPs also indicated tar balls present in this fire. Parameterization of the plume INP data on a per-unit-aerosol surface area basis confirmed that smoke is not an efficient source of INPs. Nevertheless, the high numbers of particles released from, and ubiquity of western US wildfires in summertime, regionally elevate INP concentrations in the free troposphere.