3D tomography for SCIAMACHY limb and nadir measurements: retrieval of stratospheric NO2, BrO and OClO profiles and their application for the investigation of stratospheric chemistry

卫星测量有助于了解与平流层臭氧损失有关的过程，例如对臭氧及其消耗物质进行全球和长期监测。例如，SCIAMACHY在ENVISAT上进行的肢体几何测量，直到最近才在很大程度上提高了对BrO和OClO等物种垂直分布的认识。然而，仍然有一些重要的问题有待解决，例如氯在不同种类的气溶胶和极地平流层云上的活化过程。此外，寿命非常短的物种在平流层溴收支中的作用或布鲁尔-多布森环流可能增强的影响还没有完全了解。在全球范围内，由于太阳光照、大气化学和运输，消耗臭氧物种的垂直分布在空间和时间上存在显著差异。特别强的梯度发生在黄昏区附近或跨越平流层运输障碍（极地涡旋边界、亚热带运输障碍）。这些区域对平流层下层和对流层上层的化学和运输特别重要，因为它们在大尺度上分离气团，但也使它们之间的交换成为可能。假设水平均匀性的标准一维剖面检索由于忽略了水平梯度对测量的影响而导致较大的系统偏差。我们建议开发、改进和应用一种层析剖面检索算法，该算法将SCIAMACHY肢体和最低点测量提供的信息最佳地结合起来。在SCIAMACHY任务（2002-2012）的10年中，将开发一个改进的全球平流层NO2、BrO和OClO三维剖面数据集，与大气化学模拟进行比较，并应用于大气科学的选定问题。本项目开发的数据集对于研究平流层化学和运输过程的复杂相互作用将非常有用，并将有助于减少臭氧消耗物种分布的不确定性，特别是在水平不均匀性很大的地区。

Satellite measurements strongly contribute to the understanding of the processes related to stratospheric ozone loss, e.g. by global and long term monitoring of ozone and its depleting substances. For instance, measurements performed in limb geometry by SCIAMACHY on ENVISAT largely improved the knowledge about the vertical distribution of species like BrO and OClO only recently. However, there are still important open questions, like e.g. the chlorine activation processes on different kinds of aerosols and polar stratospheric clouds. Also, the role of very short lived species in the stratospheric bromine budget or the effects of a possible enhancement of the Brewer-Dobson circulation are not fully understood. Globally, the vertical distribution of ozone depleting species varies significantly in space and time due to solar illumination, atmospheric chemistry and transport. Especially strong gradients occur near the twilight zone or across stratospheric transport barriers (polar vortex boundary, subtropical transport barriers). These regions are of particular importance for chemistry and transport of the lower stratosphere and upper troposphere, since they separate air masses on large scales but also enable exchange between them.Standard 1-D profile retrievals, which assume horizontal homogeneity, result in large systematic biases due to neglecting the effect of horizontal gradients on the measurement. We propose to develop, improve and apply a tomographic profile retrieval algorithm, which optimally combines the information provided by the SCIAMACHY limb and nadir measurements. An improved global dataset of 3D stratospheric profiles for NO2, BrO and OClO for the 10 years of the SCIAMACHY mission (2002-2012) will be developed, compared to atmospheric chemistry simulations and applied to selected questions of atmospheric science. The dataset developed in this project will be very useful for investigating the complex interplay of stratospheric chemistry and transport processes, and will help to reduce the uncertainties in the distribution of ozone depleting species, in particular for regions with large horizontal inhomogeneity.