Two campaigns measuring ammonia (NH₃) emissions with different measurement techniques were performed on a large grass field (26 ha) after the application of liquid animal manure. The aim was to compare emissions from a confined area estimated from either (i) concentration measurements, both point and line-integrated measurements, combined with backward Lagrangian stochastic (bLS) dispersion modeling or by (ii) estimation of the vertical flux by the aerodynamic gradient method (AGM) with and without footprint correction approximated by the bLS model estimates of the flux footprint. The objective of the comparison is to establish the best practice to derive NH₃ emissions from a large field. NH₃ emissions derived from bLS agreed well when comparing point and line-integrated measurements. Simple point measurements combined with bLS yield good emission estimations for the confined area. Without footprint correction, the AGM underestimates the emissions by up to 9% compared to the footprint-corrected AGM results. The sensitivity of the measurement methods makes it possible to quantify NH₃ emissions with diurnal patterns even five days after a field application of liquid animal manure under wet conditions. The bLS model proves to be a strong tool to determine the NH₃ emissions from point concentration measurements inside a large field after a slurry application.

中文翻译：

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NH3排放的计算，后向拉格朗日随机扩散模型和空气动力学梯度法的评估

施用液态动物粪便后，在一块大草地（26公顷）上进行了两次使用不同测量技术测量氨（NH ₃）排放的活动。目的是比较密闭区域的排放，该密闭区域的排放是通过以下方式估算的：（i）浓度测量，点和线积分测量，反向拉格朗日随机（bLS）弥散模型或（ii）通过空气动力学估算垂直通量通过bLS模型估算的磁通量足迹，可以估算出有无足迹校正的梯度方法（AGM）。进行比较的目的是建立最佳实践，以从大油田中获取NH ₃排放量。NH ₃比较点和线积分测量值时，bLS产生的排放量非常一致。简单的点测量与bLS相结合，可以在密闭区域获得良好的发射估算。如果不进行足迹校正，则与经足迹校正的AGM结果相比，AGM会低估多达9％的排放量。测量方法的灵敏度使得即使在潮湿条件下田间应用液态动物粪便后五天，也能够以昼夜模式对NH ₃排放进行量化。事实证明，bLS模型是确定浆液施用后从大范围内的点浓度测量值确定NH ₃排放量的强大工具。