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）是地球大气中的重要组成部分。它从中层延伸到下部热层（MLT），即从海拔约80 km到500 km以上。 O是通过通过紫外辐射对分子氧的光解生成的。它是MLT中最丰富的物种，也是MLT光化学的重要组成部分。另外，O对于MLT的能量预算很重要，因为与O的碰撞和激发的CO2分子在红外线中辐射并冷却MLT会激发CO2分子。这意味着全球气候变化也会影响MLT，因为MLT中二氧化碳浓度的增加会导致更有效的冷却，因此MLT的缩小。 O浓度受动态运动，垂直传输，潮汐和风的影响，因此，对O及其浓度谱的全球分布以及差异和年变化的准确了解对于了解光化学，能量预算和MLT的动态至关重要。该提案的目的是使用4.74 THz和2.06 THz的精细结构过渡确定MLT中O的色谱柱密度和浓度曲线。将分析的数据是通过索非亚船件上的Great/Eutgreat（德国天文学的德国接收器（德国的天文学））测量的，即红外天文学的平流层观测值。这是一种直接观察方法，它可能比现有的基于卫星的方法产生更准确的结果，该方法涉及光化学模型以得出O浓度曲线。该乐器从2014年5月开始提供大约500,000个光谱的数据库，并涵盖了四个不同的地理位置，即北美，新西兰，欧洲和大溪地/太平洋。将研究时间变化以及太阳周期，风和重力波的影响。结果将与卫星数据进行比较，卫星数据可用于80至100 km的高度，并与半经验模型的预测进行比较。应当指出，这些数据是MLT中O的第一个频谱解决，直接测量的。与基于光化学模型的间接方法相比，这是确定O浓度的有望选择。