Source and Pathway Sensitivity in Troposphere-to-Stratosphere Transport: An Adjoint-Based Approach

大气对流层上部/平流层下部区域（8- 20公里）的臭氧是地球辐射收支的重要组成部分，因此在决定气候方面发挥作用。众所周知，该地区的臭氧对卤代物质的化学消耗很敏感。自1989年《蒙特利尔议定书》生效以来，氯氟烃（CFCs）等长寿命卤化物质的排放量一直在下降。因此，人们的兴趣集中在化学寿命较短的替代物种以及海洋排放的天然卤化物种。这些物种中有许多被称为“寿命极短的物种"，其化学寿命为六个月或更短，这一相对较短的寿命意味着，所排放的化学品中有多少随后到达平流层下部，从而可能造成臭氧消耗，这一点是不确定的。特别是，到达平流层下部的比例可能对化学品排放的地理位置高度敏感，因为与当地天气模式有关的迁移效应不同。目前的提案旨在量化不同地理排放位置对垂直卫星着陆系统向平流层下部传输的相对重要性。此外，还将以“敏感度图”的形式计算在不同地点排放的示例性变结构激光器的臭氧消耗潜能值。敏感性地图将使决策者能够直接评估如果特定的地面站点排放特定的VSLS可能发生的臭氧消耗量。提出了一种新的方法来计算的敏感性地图，解决的基础上的“伴随”的化学输运方程，提出。除了有效地解决VSLS问题的新方法有可能被应用到许多不同的问题，在大气化学和运输。因此，该提案的第二个目的是在英国大气科学界推广伴随方法。

Ozone in the upper troposphere / lower stratosphere region of the atmosphere (8-20km) is an important component in Earth's radiative budget, and therefore has a role in determining climate. Ozone in this region is also known to be sensitive to chemical depletion by halogenated species. Since the Montreal protocol came in to force in 1989, emissions of long-lived halogenated species such as chloro-fluoro carbons (CFCs) have been in decline. Consequently, interest has focussed on replacement species with shorter chemical lifetimes, as well as natural halogenated species emitted from the oceans. Many of these species, known as `very short-lived species' (VSLS), have chemical lifetimes of six months or less. The relatively short lifetime means that the proportion of an emitted chemical that subsequently reaches the lower stratosphere, where it may cause ozone depletion, is uncertain. In particular, the proportion reaching the lower stratosphere may be highly sensitive to the geographical location where the chemical is emitted, due to differing transport effects associated with local weather patterns. The current proposal aims to quantify the relative importance of different geographical emission locations for the transport of VSLS to the lower stratosphere. Further, the ozone depletion potential of example VSLS emitted at different locations will be calculated in the form of a `sensitivity map'. The sensitivity maps will allow policymakers to straightforwardly assess the amount of ozone depletion that is likely to occur if a particular VSLS is emitted from a particular surface site. A novel approach to calculate the sensitivity maps, based on solving the `adjoint' to the chemistry-transport equation, is proposed. In addition to efficiently solving the VSLS problem the new method has the potential to be applied to many different problems in atmospheric chemistry and transport. A secondary aim of the proposal is therefore to promote the adjoint approach within the UK atmospheric science community.