EAGER: What is the Cause of Strong Carbon Dioxide 15 Micron Emission in the Mesosphere and Lower Thermosphere? Resolving the Puzzle

该合同支持一项为期2年的研究，研究中间层和低层热层（MLT）区域的各种红外（IR）发射机制，这些机制可能是造成~90 km以上CO2 15-μm波段红外发射增强的主要原因。这种15 μm的辐射是地球、金星和火星的mlt的主要冷却机制。这种红外发射也被许多卫星仪器（如SABER/TIMED、MIPAS/ENVUSAT-1、CRISTA/ASTRO-SPAS等）用于检索MLT温度。在MLT区域，CO2分子与O（3P）原子的非弹性碰撞激发和随后的15 μm量子发射主导了该辐射的形成。然而，尽管在过去的几十年里进行了许多研究，人们对这一过程仍然知之甚少。不同实验室采用不同技术进行的实验室测量发现CO2+O（3P）反应速率系数值较低。在模型计算中使用这种低速率不会产生再现所观察到的强CO2 15-μm发射所需的CO2（ν2）激发。为了符合这些观察结果，实验室速率必须增加4倍。该奖项旨在寻找当前MLT红外发射的非局部热力学平衡（non-LTE）模型中未考虑的一种或多种重要的CO2激发机制。该奖项的特点是包含了许多完全不同的复杂的能量转移到分子振动和旋转状态的过程，这些过程可能在MLT区域被激发。新的研究有望更准确地了解15 μm红外发射如何成为MLT区域的主要红外冷却途径。新的结果可能对MLT地区的大气动力学、化学和气候的建模产生重大影响。此外，这项研究将提供更可靠的红外辐射分析，可以扩展到其他太空任务，包括那些旨在观察火星，金星和类地系外行星的任务。该奖项还将审查是否需要对大气环流中MLT的红外辐射冷却/加热计算进行重大修改。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports a 2-year investigation into various infrared (IR) emission mechanisms in the Mesosphere and Lower Thermosphere (MLT) region that may be responsible for largely unexplained enhanced IR emission in the CO2 15-μm band above ~90 km. This 15-μm emission is the main cooling mechanism of MLTs of Earth, Venus and Mars. This IR emission is also used to retrieve MLT temperatures by a number of satellite instruments such as SABER/TIMED, MIPAS/ENVUSAT-1, CRISTA/ASTRO-SPAS, and others. In the MLT region the formation of this radiation is dominated by excitation of CO2 molecules by inelastic collisions with the O(3P) atoms and subsequent emission of the 15-μm quanta. However, this process remains still poorly understood despite many studies over the past several decades. Laboratory measurements at different laboratories applying various techniques have found low values of the CO2+O(3P) reaction rate coefficient. The use of this low rate in the model calculations does not result in the CO2(ν2) excitation needed to reproduce the strong CO2 15-μm emission observed. In order to fit these observations, the laboratory rate must be increased by a factor of 4. This award is aimed at a search for one or more significant mechanisms of the CO2 excitation that is not accounted for in the current non-local thermodynamic equilibrium (non-LTE) models of the MLT IR emissions. This award would feature the inclusion of a number of radically different and complex processes of energy transfer to molecular vibrational and rotational states which may be excited in the MLT region. The new investigation is expected to lead to a more accurate understanding of how this 15-μm IR emission serve as the main IR cooling pathway for the MLT region. The new results would potentially have high impact on the modeling of atmospheric dynamics, chemistry and climate for the MLT region. Additionally, this study will provide a more robust analysis of IR radiances that can be later expanded to other space missions, including those designed to observe Mars, Venus and terrestrial exo-planets. The award would also examine whether there is a need for significant alteration of the calculations of the IR radiative cooling/heating of MLT in GCMs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.