Satellite ammonia (NH₃) observations provide unprecedented insights into NH₃ emissions, spatiotemporal variabilities and trends, but validation with in situ measurements remains lacking. Here, total columns from the Infrared Atmospheric Sounding Interferometer (IASI) were intercompared to boundary layer NH₃ profiles derived from aircraft‐ and surface‐based measurements primarily in Colorado, USA, in the summer of 2014. IASI‐NH₃ version 3 near real‐time data set compared well to in situ derived columns (windows ±15 km around centroid, ±1 h around overpass time) with a correlation of 0.58, a slope of 0.78 ± 0.14 and an intercept of 2.1 × 10¹⁵±1.5 × 10¹⁵ molecules cm⁻². Agreement degrades at larger spatiotemporal windows, consistent with the short atmospheric lifetime of NH₃. We also examined IASI version 3R data, which relies on temperature retrievals from the ERA Reanalysis, and a third product generated using aircraft‐measured temperature profiles. The overall agreement improves slightly for both cases, and neither is biased within their combined measurement errors. Thus, spatiotemporal averaging of IASI over large windows can be used to reduce retrieval noise. Nonetheless, sampling artifacts of airborne NH₃ instruments result in significant uncertainties of the in situ‐derived columns. For example, large validation differences exist between ascent and descent profiles, and the assumptions of the free tropospheric NH₃ profiles used above the aircraft ceiling significantly impact the validation. Because short‐lived species like NH₃ largely reside within the boundary layer with complex vertical structures, more comprehensive validation is needed across a wide range of environments. More accurate and widespread in situ NH₃ data sets are therefore required for improved validations of satellite products.

中文翻译：

---

使用原位垂直剖面在像素尺度上验证IASI卫星氨观测

卫星氨（NH ₃）观测为NH ₃排放，时空变化和趋势提供了空前的见解，但仍缺乏现场测量的验证。在这里，红外大气探测仪（IASI）的总柱与边界层NH ₃剖面进行了比对，边界NH ₃剖面主要来自于美国科罗拉多州的飞机和地面测量，于2014年夏季进行。IASI‐NH ₃版本3接近真实时间数据集与原位衍生色谱柱（窗口在质心附近±15 km，越过时间在±1 h附近）进行了很好的比较，相关系数为0.58，斜率为0.78±0.14，截距为2.1×10 ¹⁵ ±1.5×10 ^15个分子cm ^-2。在较大的时空窗处，相符性降低，这与NH ₃的短大气寿命一致。我们还检查了IASI版本3R数据，该数据依赖于ERA重新分析获得的温度，以及使用飞机测得的温度曲线生成的第三种产品。两种情况的总体一致性都略有提高，并且在两者的组合测量误差范围内均没有偏差。因此，可以使用大窗口上的IASI的时空平均来减少检索噪声。但是，机载NH ₃仪器的采样伪像会导致原位色谱柱的显着不确定性。例如，上升和下降曲线以及自由对流层NH ₃的假设之间存在很大的验证差异飞机天花板上方使用的轮廓会严重影响验证。由于像NH ₃这样的短命物种主要位于具有复杂垂直结构的边界层内，因此需要在广泛的环境中进行更全面的验证。因此，需要更准确和广泛的原位NH ₃数据集，以改进卫星产品的验证。