Atomic oxygen in the mesosphere and lower thermosphere of the Earth

地球中层和低层热层中的原子氧

• 批准号: 502949516
• 负责人: Professor Dr. Heinz-Wilhelm Hübers
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/502949516?language=en
• 关键词: Atomic; oxygen; mesosphere; lower; thermosphere

Atomic oxygen (O) is an important component of the Earth’s atmosphere. It extends from the mesosphere to the lower thermosphere (MLT), i.e. from approximately 80 km to beyond 500 km in altitude. O is generated through photolysis of molecular oxygen by UV radiation. It is the most abundant species in the MLT and an important component with respect to the photochemistry of the MLT. In addition, O is important for the energy budget of the MLT, because CO2 molecules are excited by collisions with O and the excited CO2 molecules radiate in the infrared and cool the MLT. This means that global climate change also affects the MLT, because the increase of the CO2 concentration in the MLT leads to a more efficient cooling and consequently shrinking of the MLT. The O concentration is affected by dynamical motions, vertical transport, tides, and winds Therefore, an accurate knowledge of the global distribution of O and its concentration profile as well as diurnal and annual variations are essential for understanding the photochemistry, the energy budget and the dynamics of the MLT. The goal of this proposal is to determine column densities and concentration profiles of O in the MLT using the fine structure transitions at 4.74 THz and 2.06 THz. The data, which will be analyzed, are measured with the GREAT/upGREAT (German REceiver for Astronomy at Terahertz frequencies) heterodyne spectrometer on board of SOFIA, the Stratospheric Observatory for Infrared Astronomy. This is a direct observation method which may yield more accurate results than existing indirect satellite-based methods which involve photochemical models in order to derive O concentration profiles. This instrument provides a data base with approximately 500,000 spectra starting in May 2014 and covering four different geolocations, namely North America, New Zealand, Europe and Tahiti/Pacific. Temporal variations as well as the influence of solar cycles, winds and gravity waves will be studied. The results will be compared with satellite data, which are available for altitudes from 80 to 100 km, and with predictions from a semi-empirical model. It should be noted that these data are the first spectrally resolved, direct measurement of O in the MLT. This is a promising alternative for the determination of the O concentration compared to indirect satellite-based methods, which rely on photochemical models.

原子氧 (O) 是地球大气层的重要组成部分，它从中间层延伸到低层热层 (MLT)，即从海拔约 80 公里到 500 公里以上，O 是通过紫外线辐射光解分子氧而产生的。它是 MLT 中最丰富的物种，也是 MLT 光化学的重要组成部分。此外，O 对于 MLT 的能量预算很重要，因为 CO2 分子被激发。与 O 和激发的 CO2 分子的碰撞会辐射红外线并冷却 MLT，这意味着全球气候变化也会影响 MLT，因为 MLT 中 CO2 浓度的增加会导致更有效的冷却，从而导致 MLT 收缩。 O 浓度受动力运动、垂直输送、潮汐和风的影响。因此，准确了解 O 的全球分布及其浓度分布以及日和年变化对于了解光化学、该提案的目标是使用 4.74 THz 和 2.06 THz 的精细结构转变来确定 MLT 中 O 的柱密度和浓度分布。平流层红外天文台 SOFIA 上的 GREAT/upGREAT（德国太赫兹频率天文学接收器）外差光谱仪。是一种直接观测方法，与现有的基于卫星的间接方法相比，该方法可以产生更准确的结果，后者涉及光化学模型，以得出 O 浓度剖面。该仪器从 2014 年 5 月开始提供约 500,000 个光谱的数据库，涵盖四个不同的地理位置。将研究北美、新西兰、欧洲和塔希提岛/太平洋的时间变化以及太阳周期、风和重力波的影响，并将其结果与卫星数据进行比较。高度从 80 公里到 100 公里，并根据半经验模型进行预测。值得注意的是，这些数据是 MLT 中首次对 O 进行光谱解析的直接测量。这是确定 O 浓度的一个有前途的替代方案。与依赖光化学模型的间接卫星方法相比。