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.

该奖项支持对中层和低层热层 (MLT) 区域的各种红外 (IR) 发射机制进行为期 2 年的研究，这些机制可能是导致大约 90 公里以上 CO2 15 μm 波段中红外发射增强的主要原因。 -μm 发射是地球、金星和火星 MLT 的主要冷却机制。这种红外发射也用于通过 SABRE/TIMED 等许多卫星仪器检索 MLT 温度。 MIPAS/ENVUSAT-1、CRISTA/ASTRO-SPAS 等区域中，这种辐射的形成主要是通过与 O(3P) 原子非弹性碰撞激发 CO2 分子以及随后发射 15 μm 量子。然而，尽管过去几十年来不同实验室应用各种技术进行的许多研究发现 CO2+O(3P) 反应速率系数值较低，但人们对这一过程仍然知之甚少。在模型计算中使用这种低速率不会导致重现观察到的强 CO2 15-μm 发射所需的 CO2(ν2) 激发，为了适应这些观察结果，实验室速率必须增加 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 发射的非局部热力学平衡（非 LTE）模型中未得到考虑。数量能量转移到分子振动和旋转状态的完全不同且复杂的过程可能在 MLT 区域被激发，新的研究预计将有助于更准确地理解这种 15 微米红外发射如何作为主要的红外冷却路径。新的结果可能会对 MLT 区域的大气动力学、化学和气候建模产生重大影响，此外，这项研究还将提供更可靠的红外辐射分析，以便以后扩展到其他太空任务。 ，包括那些旨在观测火星、金星和类地系外行星。该奖项还将审查是否需要对 GCM 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 NSF 的法定使命，并被视为值得通过使用基金会的智力优点和更广泛的影响审查标准进行评估来支持。