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

EAGER：中层和低热层强烈二氧化碳 15 微米排放的原因是什么？

• 批准号: 2125760
• 负责人: Alexander Kutepov
• 金额: $ 12.28万
• 依托单位: Catholic University of America
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2125760&HistoricalAwards=false
• 关键词: EAGER; What; Cause; Strong; Carbon

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.

该奖项支持对中间层和低热层（MLT）区域的各种红外（IR）发射机制进行为期两年的研究，这些机制可能是导致CO2 15 μm波段~90 km以上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MLT的主要冷却机制。这一红外辐射也被许多卫星仪器用于反演MLT温度，如SABER/TIMED、MIPAS/ENVUSAT-1、CRISTA/ASTRO-SPAS等。在MLT区，这种辐射的形成是由CO2分子与O（3 P）原子的非弹性碰撞激发和随后的15 μm量子发射所主导的。然而，尽管在过去几十年中进行了许多研究，但对这一过程仍然知之甚少。在不同的实验室采用各种技术的实验室测量发现的CO2+O（3 P）反应速率系数的低值。在模型计算中使用这种低速率并不会导致重现所观察到的强CO2 15 μm发射所需的CO2（ν2）激发。为了符合这些观察结果，实验室率必须增加4倍。该奖项旨在寻找一种或多种重要的CO2激发机制，这些机制在当前MLT IR排放的非局部热力学平衡（非LTE）模型中没有考虑到。该奖项将包括一些完全不同和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。这项新的研究有望更准确地理解这种15 μm的红外辐射是如何作为MLT区域的主要红外冷却途径的。新的结果可能会对MLT地区的大气动力学，化学和气候建模产生很大影响。此外，这项研究将提供一个更强大的红外辐射分析，以后可以扩展到其他空间任务，包括那些旨在观察火星，金星和地球系外行星。该奖项还将审查是否有必要对大气环流模型中MLT的红外辐射冷却/加热的计算进行重大修改。该奖项反映了NSF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。