We present retrievals of infrared spectral surface emissivities spanning the far infrared and mid‐infrared from aircraft observations over Greenland, taken at an altitude of 9.2 km above sea level. We describe the flight campaign, available measurements, and the retrieval method. The principal barriers to reducing uncertainty in the emissivity retrievals are found to be instrumental noise and our ability to simultaneously retrieve the underlying surface temperature. However, our results indicate that using the instrumentation available to us it is possible to retrieve emissivities from altitude with an uncertainty of ~0.02 or better across much of the infrared. They confirm that the far‐infrared emissivity of snow and ice surfaces can depart substantially from unity, reaching values as low as 0.9 between 400 and 450 cm⁻¹. They also show good consistency with retrievals from the same flight made from near‐surface observations giving confidence in the methodology used and the results obtained for this more challenging viewing configuration. To the best of our knowledge, this is the first time that far‐infrared surface emissivity has been retrieved from altitude and demonstrates that the methodology has the potential to be extended to planned satellite far‐infrared missions.

中文翻译：

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从高空飞机飞行中检索高空表面发射率的整个红外

我们提供了从格陵兰岛飞机观测到的，覆盖远红外和中红外的红外光谱表面发射率的信息，该观测是在海拔9.2 km的高度上进行的。我们描述了飞行战役，可用的度量以及检索方法。发现减少发射率检索不确定性的主要障碍是仪器噪声以及我们同时检索下层表面温度的能力。但是，我们的结果表明，使用我们现有的仪器，可以从海拔上获取发射率，并且在大部分红外线中的不确定度约为0.02或更好。他们证实，雪和冰表面的远红外发射率可以大幅度偏离单位，在400至450 cm ^-1之间可低至0.9。它们还显示出与从近地表观测进行的同一次飞行的取回具有良好的一致性，从而使人们对所用的方法论以及这种更具挑战性的观察配置所获得的结果充满信心。据我们所知，这是第一次从海拔高度获取远红外表面发射率，并证明该方法具有扩展到计划中的卫星远红外任务的潜力。