NOx and HOx production by energetic electrons and impacts on polar stratospheric ozone (NOHO)

预测未来的气候变化与了解当前和最近的过去气候系统正在发生的变化密切相关。极地地区的研究为我们了解全球气候提供了重要线索，并提供了由自然过程耦合引起的变化的早期迹象，例如太阳到达地球的能量的变化，以及人为因素。例如，极地冬季提供了极端寒冷、黑暗的大气条件，加上人造氯氟烃（CFC）气体释放的化学物质，自20世纪80年代以来，每年春季都会破坏距地面18-25公里的平流层臭氧层。南半球臭氧“空洞”现在与观测到的南极表面温度和海冰的变化、南大洋对二氧化碳吸收的减少以及大气环流的扰动有关，这种扰动可以影响远至北半球的天气模式。由于国际议定书禁止氯氟烃，臭氧层有望恢复，但这可能会被我们释放到大气中的其他温室气体和自然过程（包括太阳输出的变化）所推迟。虽然在典型的11年太阳活动周期中，太阳光的总能量变化很小（~0.1%），但从太阳流出的高能电子和质子在时间尺度上发生了巨大变化，从小时到年不等。这些粒子受地球磁场的引导，可以进入高层大气，最强烈的是在极地地区。一个可见的影响是极光，但这些粒子也可以显著地改变大气的化学成分，一直到平流层的臭氧层。强大的太阳风暴还会破坏卫星，扰乱电力网络。然而，太阳产生的高能电子进入地球大气层的机制，以及影响平流层臭氧的复杂的相互作用过程，都没有得到很好的理解，这限制了我们准确预测未来臭氧变化和对气候影响的能力。我们建议通过在南极洲哈雷站对中层大气的观测来回答有关高能电子对平流层臭氧影响的主要未解决的问题。这个位置就在高能电子进入大气层的主要区域的正下方，因此非常适合观察由此产生的效应。我们将在那里安装一个最先进的微波辐射计，以及由BAS科学家运行的其他设备。通过分析高空大气自然发射的微波，我们可以计算出在地面以上30-90公里处有多少臭氧，并测量大气中由影响臭氧的高能电子产生的化学物质。我们将在两个完整的南极年/冬季（2013年1月至2015年2月）进行观测，并借助环绕地球运行的航天器的数据进行解释，并测量进入大气层的高能电子。我们将利用南极观测并开发基于计算机的模型，以更好地了解高能电子对大气的影响。最终目标是进一步了解导致极地地区和全球气候变化的过程-这与英国环境科学和国际层面的合作研究高度相关，其中BAS和利兹发挥了关键作用。

Predicting future climate change is intimately linked to understanding what is happening to the climate system in the present, and in the recent past. Studies in the Polar Regions provide vital clues in our understanding of global climate, and early indications of changes arising from the coupling of natural processes, such as variability in the amount of energy from the Sun reaching the Earth, and man-made factors. For example, the polar winter provides the extreme cold, dark conditions in the atmosphere which, combined with chemicals released from man-made chlorofluorocarbon (CFC) gases, has led to destruction of the stratospheric ozone layer 18-25 km above the ground every spring-time since the 1980's. The Southern hemisphere ozone 'hole' is now linked to observed changes in surface temperature and sea-ice across Antarctica, decreased uptake of carbon dioxide by the Southern Ocean, and perturbations to the atmospheric circulation that can affect weather patterns as far away as the Northern hemisphere.Recovery of the ozone layer is expected now that CFC's are banned by international protocols, but this may be delayed by other greenhouse gases we are releasing into the atmosphere and natural processes including changes in the Sun's output. Although the total amount of energy as sunlight changes by a small amount (~0.1%) over the typical 11-year solar cycle, the energetic electrons and protons streaming from the Sun changes dramatically on timescales from hours to years. These particles are guided by the Earth's magnetic field and can enter the upper atmosphere, most intensely over the Polar Regions. A visible effect is the aurora, but the particles can also significantly modify the chemistry of the atmosphere down to the stratospheric ozone layer. Powerful solar storms can also damage satellites and disrupt electrical power networks. However the mechanisms by which energetic electrons generated by the Sun enter the Earth's atmosphere, and the complex, interacting processes that affect stratospheric ozone are not well understood, which limits our ability to accurately predict future ozone changes and impacts on climate.We propose answering major unresolved questions about the impact of energetic electrons on stratospheric ozone by making observations of the middle atmosphere from Halley station in Antarctica. This location is directly under the main region where energetic electrons enter the atmosphere, making it ideal to observe the resulting effects. We will install a state-of-the-art microwave radiometer there alongside other equipment run by BAS scientists. By analysing the microwaves naturally emitted by the atmosphere high above us we can work out how much ozone there is 30-90 km above the ground as well as measuring chemicals produced in the atmosphere by energetic electrons that affect ozone. We will make observations throughout two complete Antarctic years/winters (1/2013-2/2015) and interpret them with the help of data from spacecraft that orbit the Earth and measure the energetic electrons entering the atmosphere. We will use the Antarctic observations and develop computer-based models to better understand the impact of energetic electrons on the atmosphere. The ultimate goal is to further understanding of the processes that lead to climate variability in the Polar Regions and globally - highly relevant for UK environmental science and collaborative research at an international level in which BAS and Leeds play a key role.