Investigation of the photochemistry of oxygen species in the mesopause region

原子氧(O)是陆地中层顶区最重要的化学成分之一。它对该大气区域的能量平衡起着至关重要的作用。由于它的化学寿命很长，它能够长距离地传输化学势能。它间接参与了中层顶区的辐射冷却，并直接耦合到臭氧丰度较低的区域，而臭氧则控制着中间层的非绝热太阳加热。在中层顶区测量O的数量相当有限，现有的大多数观测都是基于对O2、O和OH气辉发射的测量。这些测量是间接测量，通常需要了解大量的光化学速率常数。现有的研究提供了明确的证据，表明目前用来描述O2 A带、O绿线和OH Meinel发射的模型是不一致的，它们都是由原子氧驱动的。在这项提议的框架内，我们计划调查上述三种气辉排放的现有光化学模型的一致性。这将利用对所有三种排放的卫星同步观测和专用模型模拟的协同作用来完成。将使用的卫星测量是使用Envisat航天器上的SCIAMACHY(大气制图扫描成像吸收光谱仪)仪器进行的，该航天器于2002年至2012年运行。SCIAMACHY是唯一适合于这一目的的，因为它的光谱范围很广，涵盖了与这项提议相关的所有气辉排放，并提供了对这些排放的同步和光谱分辨率观测。计划中的模型模拟将使用一套已建立的光化学和全球模型进行。使用逆模型方法，我们计划通过同时最小化模型结果与SCIAMACHY观测之间的差异来进行光化学模型参数的优化。此外，我们计划对中层顶区O的空间和时间变化进行彻底的表征，特别是2002年至2012年期间的太阳影响和潜在的长期变化。此外，我们的目标是利用这个项目中得出的O时间序列来改进现有的中层顶区O的气候学模型(例如，MSIS)--这些模型在不同方面显然是不充分的。申请者是其主要研究领域的知名专家，分别在使用地面气辉排放的卫星遥感领域和大气建模领域拥有长期经验。

Atomic oxygen (O) is one of the most important chemical constituents of the terrestrial mesopause region. It plays an essential role for the energy balance of this atmospheric region. Due to its long chemical lifetime it is capable of transporting chemical potential energy over large distances. It participates indirectly in the radiative cooling of the mesopause region and it is directly coupled to the less abundant ozone, which in turn governs diabatic solar heating of mesosphere. The number of O measurements in the mesopause region is rather limited, and most of the available observations are based on measurements of the O2, O and OH airglow emissions. These measurements are indirect measurements and generally require knowledge of a large number of photochemical rate constants. Existing studies provide clear evidence that the currently used models to describe the O2 A-band, the O green line and the OH Meinel emissions, which are all driven by atomic oxygen, are inconsistent. Within the frame of this proposal we are planning on investigating the consistency of the existing photochemical models of the three airglow emissions mentioned. This will be done using the synergy of simultaneous satellite observations of all three emissions and dedicated model simulations. The satellite measurements to be used were carried out with the SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on the Envisat spacecraft, which operated from 2002 to 2012. SCIAMACHY is uniquely suited for this purpose, because with its broad spectral range it covers all the airglow emissions relevant for this proposal and provides simultaneous and spectrally resolved observations of these emissions. The planned model simulations will be performed with a suite of established photochemical and global models. Using an inverse modelling approach, we plan on carrying out an optimization of photochemical model parameters by simultaneously minimizing the differences between model results and the SCIAMACHY observations. In addition, we plan on performing a thorough characterization of the spatial and temporal variability of O in the mesopause region, with particular focus on solar influence and potential long-term variations over the period from 2002 to 2012. Furthermore, our aim is to improve the existing climatological models of O in the mesopause region (e.g., MSIS) - which are clearly inadequate in different respects - using the O time series derived within this project. The applicants are established experts in their main research areas and have long-time experience in the area of satellite remote sensing using terrestrial airglow emissions and atmospheric modelling, respectively.