The lower stratosphere: interactions with the tropospheric chemistry/climate system

现在已经确定，大气系统是高度耦合的，一个地点的变化可以对其他地方产生重大影响。例如，平流层臭氧的变化可对地表紫外线产生重要影响。低平流层尤其重要。这是一个最近气溶胶和臭氧浓度发生变化的区域，目前已知这些变化影响了地面气候和对流层组成，尽管相互作用的细节还没有完全解决。我们预计，这一区域的组成今后将随着温室气体或消耗臭氧物质丰度的变化而变化。重要的是要评估低星层组成的任何变化对气候系统的未来影响。这是我们提案的主要目标，将通过使用合作伙伴帮助开发的化学/气候模型来实现。我们将使用UKCA模型，该模型基于最新的气象局气候模型，其中我们添加了大气化学和气溶胶的详细描述。我们将使用该模型来探索最近发生的变化所涉及的过程（例如，皮纳图博火山的大喷发将大量硫注入平流层，导致平流层气溶胶增强，随后地表温度发生变化）。我们还将使用该模型来考虑一系列臭氧“恢复”的情景，以响应蒙特利尔议定书。该模型将用于探索最近提出的地球工程解决方案的科学意义，以减轻温室气体引起的气候变化的影响。

It is now well established that the atmospheric system is highly copled and that changes in one location can have a significant impact elsewhere. For example, changes in stratospheric ozone can have an important consequence for surface UV. The lower stratosphere is especially important. Itis a region where there have been recent changes in the concentrations of aerosol and ozone which are now known to have influenced surface climate and tropospheric composition although the details of the interactions are not fully resolved. We expect that composition in this region will cahnge in the future, for example, in response to changes in the abundance of greenhouse gases or ozone-deplting substances. It is important to assess the future impact on the climate system of aqny changes in lower startospheric composition. This is the major objective of our proposal and will be achieved by using a chemistry/climate model that the partners have helped to develop. We will use the UKCA model, based on the latest Met Office climate model, into which we have added detailed descriptins of atmospheric chemistry and aerosol. We will use the model to explore the processes involved in recent past changes (e.g. after the major eruption of Mt Pinatubo which injected a large amount of sulphur into the stratosphere leading to enhanced stratospheric aerosol and subsequent changes in surface temperature). We will also use the model to consider a range of scenarios as ozone 'recovers' in response to the Montreal Protocol. The model will be used to explore the scientific implications of geoengineering solutions recently proposed to mitigate the impact of greenhouse gas induced climate change.