Atmospheric chemical species play critical roles in ecosystem functioning and climate, but spatially resolving near‐surface concentrations has been challenging. In this regard, hovering unmanned aerial vehicles (UAVs) represent an emerging technology. The study herein provides guidance for optimized atmospheric sampling by hovering copter‐type UAVs. Large‐eddy simulations are conducted for species having chemical lifetimes ranging from reactive (i.e., 10² s) to long‐lived (i.e., 10⁸ s). The case study of fair‐weather conditions over an equatorial tropical forest is used because of previous UAV deployments in this region. A framework is developed of influence length and horizontal shift of upwind surface emissions. The framework quantifies the length scale of the contribution of upwind forest emissions to species concentrations sampled by the downwind hovering UAV. Main findings include the following: (1) sampling within an altitude that is no more than 200 m above the canopy is recommended for both high‐ and intermediate‐reactivity species because of the strong decrease in species concentration even in a highly turbulent atmosphere; (2) sampling durations of at least 5 and 10 min are recommended for intermediate‐ and high‐reactivity species, respectively, because of the effects of atmospheric turbulence; and (3) in the case of heterogeneity of emissions across the underlying landscape, maximum recommended altitudes are presented for horizontal sampling strategies that can resolve the variability in the landscape emissions. The coupled effects of emission rate, wind speed, species lifetime, turbulence, and UAV sampling duration on influence length must all be considered for optimized and representative sampling over forests.

中文翻译：

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无人机悬停在热带森林上进行大气化学采样的优化和代表性

大气化学物质在生态系统功能和气候中起着关键作用，但是空间分辨近地表浓度一直是一个挑战。在这方面，盘旋无人机是一种新兴技术。本文的研究为悬停直升机型无人机提供了优化大气采样的指南。对化学寿命从反应性（即10 ² s）到长寿命（即10 ⁸）的物种进行了大涡模拟。s）。由于先前在该地区部署了无人机，因此使用了赤道热带森林上天气条件良好的案例研究。建立了影响长度和迎风面辐射水平位移的框架。该框架量化了顺风森林排放对顺风无人飞行器采样的物种浓度的贡献的长度尺度。主要发现包括以下几个方面：（1）对于高反应性和中等反应性的物种，建议在不超过冠层200 m的高度进行采样，因为即使在高度动荡的环境中，物种的浓度也会大大降低；（2）由于大气湍流的影响，对于中等和高反应性物种，建议分别至少采样5分钟和10分钟；（3）如果整个景观的排放物具有非均质性，则为可以解决景观排放物变化性的水平采样策略提供最大建议海拔高度。必须对排放率，风速，物种寿命，湍流和UAV采样持续时间对影响长度的耦合影响进行综合和优化，以对森林进行最佳采样。