EAGER: A New Look at the Middle Atmosphere through the Eyes of SABER (Sounding of the Atmosphere using Broadband Emission Radiometry)

研究人员将研究中间层和低层热层（MLT）的各种红外（IR）发射机制，这可能是在~90公里处出现的一种很大程度上无法解释的红外增强特征的原因。使用宽带发射辐射仪探测大气（SABER）是美国宇航局热层、电离层、中间层、能量学和动力学（TIMED）任务上的四种仪器之一，是一个10通道宽带四肢扫描红外辐射计，覆盖光谱范围从1.27到17微米。SABER已经提供了十年来有关动态温度、压力、臭氧、二氧化碳、水蒸气和氧原子的信息。这些结果在很大程度上受到MLT中红外发射模型质量的影响，对这些结果的解释对于理解该地区的物理和化学具有至关重要的意义。自SABER 4.3微米通道的卫星运行开始以来，就出现了类似于层状增强的红外肢体发射特征。该特征局限于对应于切线高度在85-95 km之间的高度区域，具有明显的时空变异性。尽管在所有纬度和季节都存在增强的翼缘辐射，但它们在极地夏季MLT似乎更强。对其他航天器观测结果的初步分析显示了类似的特征，尽管这些仪器的运行方式有很大的不同，这表明这至少在一定程度上是一个真实的现象。我们目前的MLT红外发射模型无法预测这种增强，特别是与在其他通道中观察到的类似效果相比。由于缺乏对其起源的了解，这种影响已经被忽视了十年，因此，航空和空间科学界通常不知道。研究人员将研究许多完全不同的跨学科方法，其中包括MLT分子、原子和离子化合物的非平衡化学及其与尘埃和冰粒的可能相互作用，光解和化学反应产物向分子振动的能量转移的各种潜在机制，非lte分子发射，不同光谱区域辐射的吸收、转化和多次散射。调查将解决一个可能改变对MLT中CO2特性的理解的特征。因此，研究结果可能对大气化学和气候产生重大影响。此外，这项研究将提供一个更可靠的红外辐射分析，可以在以后扩展到其他太空任务。

The investigators will study various Infrared (IR) emission mechanisms in the Mesosphere and Lower Thermosphere (MLT), which may be responsible for a largely unexplained enhanced IR feature at ~90 km. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), one of four instruments on board of NASA's Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission, is a 10-channel broadband limb-scanning infrared radiometer covering the spectral range from 1.27 to 17 microns. SABER has already provided a decade worth of information about kinetic temperature, pressure, ozone, carbon dioxide, water vapor and atomic oxygen. The interpretation of these results, which are strongly affected by the quality of models of the IR emissions in the MLT, have crucial importance for understanding the physics and chemistry of this region. An IR limb emission feature that resembles a layer-like enhancement has been present since the beginnings of the satellite operations in SABER's 4.3 micron channel. This feature is localized at an altitude region that corresponds to tangent heights between 85-95 km and has a distinct spatial and temporal variability. Although the enhanced limb radiances are present at all latitudes and seasons, they appear to be stronger at the polar summer MLT. Preliminary analysis of observations from other spacecraft reveal similar features although those instruments operate significantly different, which indicate this is, at least in part, a real phenomena. This enhancement is not predicted by our current IR emission models in the MLT, in particular when compared to similar effects observed in additional channels. Due to a lack of understanding of its origins, this effect has been ignored for a decade and, as a result, is generally unknown by the aeronomy and space science communities. The investigators will study a number of radically different as well as interdisciplinary approaches, among them non-equilibrium chemistry of molecular, atomic and ionic compounds of MLT and their possible interactions with dust and ice particles, various potential mechanism of energy transfer from photolysis and chemical reaction products to molecular vibrations, non-LTE molecular emission, absorption, transformation and multiple scattering of radiation in various spectral regions, etc The investigation will address a feature that may alter the understanding of the CO2 characteristics in the MLT. As such, the results may have high impact on atmospheric chemistry and climate. Additionally, this study will provide a more robust analysis of IR radiances that can be later expanded to other space missions.