Assessing Vertical Allocation of Wildfire Smoke Emissions Using Observational Constraints From Airborne Lidar in the Western U.S.
Assessing Vertical Allocation of Wildfire Smoke Emissions Using Observational Constraints From Airborne Lidar in the Western U.S.
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DOI：
10.1029/2022jd036808
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发表时间：
2022-11-16
影响因子：
4.4
通讯作者：
Wiggins, Elizabeth
中科院分区：
文献类型：
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作者：
Ye, Xinxin;Saide, Pablo E.;Hair, Johnathan;Fenn, Marta;Shingler, Taylor;Soja, Amber;Gargulinski, Emily;Wiggins, Elizabeth
野火排放物是大气中碳质气溶胶和痕量气体的主要贡献者。在浮力抬升的作用下，烟羽可以被注入到自由对流层和平流层低层，从而显著影响其对空气质量和辐射收支影响的大小和距离。然而，当烟雾逸出行星边界层（PBL）时，排放物的垂直分配及其调节机制仍不清楚。我们提出了一个逆建模框架来估计野火排放量，其时间和垂直演变受到同化气溶胶消光剖面的约束，这些剖面是在火灾对区域到全球环境和空气质量的影响实地活动期间从机载差分吸收激光雷达-高光谱分辨率激光雷达观察到的。美国西部发生三起火灾其显示出自由对流层注入。与WRF‐Chem模型使用默认羽流上升选项（12%-52%）估计的结果相比，受约束的烟雾排放表明，在PBL上方注入的烟雾比例（f >PBL，80%-94%）相对于柱总量要大得多。更新后的排放概况产生改善的模拟垂直结构的顺风输送烟雾，但有限的细化区域烟雾气溶胶光学厚度分布由于时空覆盖的飞行观测。这些结果突出了改善火灾排放物的垂直分配对推进烟气环境影响的建模和预测的意义。开发了一个逆建模框架，用于使用机载激光雷达观测来估计垂直野火排放分配。对自由对流层注入的四个火灾案例的反演表明，在行星边界层上方注入的烟雾比例大于建模的烟雾比例。受约束的排放剖面导致传输烟雾的垂直分配得到改善，但区域气溶胶光学厚度的细化有限。
Wildfire emissions are a key contributor of carbonaceous aerosols and trace gases to the atmosphere. Induced by buoyant lifting, smoke plumes can be injected into the free troposphere and lower stratosphere, which by consequence significantly affects the magnitude and distance of their influences on air quality and radiation budget. However, the vertical allocation of emissions when smoke escapes the planetary boundary layer (PBL) and the mechanism modulating it remain unclear. We present an inverse modeling framework to estimate the wildfire emissions, with their temporal and vertical evolution being constrained by assimilating aerosol extinction profiles observed from the airborne Differential Absorption Lidar‐High Spectral Resolution Lidar during the Fire Influence on Regional to Global Environments and Air Quality field campaign. Three fire events in the western U.S., which exhibit free‐tropospheric injections are examined. The constrained smoke emissions indicate considerably larger fractions of smoke injected above the PBL (f >PBL, 80%–94%) versus the column total, compared to those estimated by the WRF‐Chem model using the default plume rise option (12%–52%). The updated emission profiles yield improvements for the simulated vertical structures of the downwind transported smoke, but limited refinement of regional smoke aerosol optical depth distributions due to the spatiotemporal coverage of flight observations. These results highlight the significance of improving vertical allocation of fire emissions on advancing the modeling and forecasting of the environmental impacts of smoke. An inverse modeling framework is developed to estimate vertical wildfire emission allocation using airborne lidar observations Inversions for four fire cases with free‐troposphere injections suggest larger fractions of smoke injected above the planetary boundary layer than modeled Constrained emission profiles lead to improved vertical allocation of transported smoke but limited refinement of regional aerosol optical depth