TWISTA (The Wide-ranging Impacts of STratospheric smoke Aerosols)

TWISTA（平流层烟雾气溶胶的广泛影响）

• 批准号: NE/Y000358/1
• 负责人: Alexander Archibald
• 金额: $ 29.64万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY000358%2F1
• 关键词: TWISTA; Wide; ranging; Impacts; STratospheric

There is much new evidence of stratospheric intrusions of smoke from intense pyro-cumulonimbus (pyroCb) events from wildfires. These events appear to be increasing in frequency, intensity and plume height in both the northern and southern hemispheres. The impacts of smoke aerosol on climate may be disproportionately larger than volcanic aerosols that are sporadically injected into the stratosphere because i) they strongly absorb sunlight which may influence stratospheric dynamics and ii) their surface characteristics may enhance their role in heterogeneous chemistry and ozone depletion. Given that the record persistent Antarctic ozone hole and record Arctic ozone depletion of 2020 were preceded by unprecedented wildfires, there is an urgent need to understand their role in the climate system. In the northern hemisphere, the strongest stratospheric smoke events have occurred over the past five years. In 2017, a range of remote sensing observations showed that smoke from the Pacific Northwest event (PNE) persisted at 18-22 km altitude for over 5 months. In 2019-2020, stratospheric aerosol loading was anomalously high owing to sulfate and ash from the Raikoke eruption but there is evidence of a possible significant contribution from smoke from the August 2019 Siberian wildfires (SIB). Record halogen-catalysed Arctic ozone depletion was observed in spring of 2020 with a strong Arctic polar vortex cold enough for polar stratospheric clouds (PSCs) to form until well until springtime. Research has suggested that, in the absence of the Montreal Protocol which has reduced humanity's emissions of ozone depleting substances (ODSs), we would have had a northern hemisphere ozone hole, similar to that of the Antarctic. In the southern hemisphere, the January 2020 Australian 'Black Summer' (ABS) wildfires were unprecedented in scale and intensity with millions of tonnes of smoke aerosol and associated gases being injected into the upper troposphere and lower stratosphere. Initial injection altitudes reached 16 km and the smoke eventually reached altitudes of up to 36 km (three times higher than the operating altitude of commercial trans-Atlantic jet aircraft. The ascent to remarkably high altitudes resulted from the self-lofting caused by the presence of black carbon (BC) within smoke which absorbs sunlight and heats the air surrounding it. Just like a hot air-balloon, this absorption of sunlight causes the smoke and the surrounding air to rise. Significantly, it appears that this single event caused the largest global mean stratospheric temperature perturbation for three decades. The Antarctic ozone hole in 2020 was extremely deep and persistent, with record low polar stratospheric temperatures and a strong polar vortex.Several chemical fingerprints determined from satellite observations that suggest that the severe ozone depletion in the Arctic, and the record ozone hole in the Antarctic are linked to these wildfire events. This becomes even more worrying when one considers that wildfire frequency, intensity, and plume altitude are all forecast to increase under future global warming scenarios. It could be postulated that all of the hard work that has been performed very successfully under the Montreal Protocol might be undone not through lack of adherence to ODS reductions, but through global warming. If an ozone hole opens up over the northern hemisphere, this could pose a further existential threat to the delicate ecosystem balance that humanity relies upon. Similarly, the dynamical impacts of absorbing aerosols in the stratosphere may directly impact the Earth's surface climate: an enhanced positive phase of the North Atlantic Oscillation has been modelled in idealised studies which could lead to enhanced flooding in northern Europe and potentially devastating drought over the Iberian Peninsula. It is therefore critical to include these factors and feedbacks in global climate simulations at the earliest opportunity.

有许多新证据表明，野火引发的强烈火积雨云 (pyroCb) 事件导致烟雾侵入平流层。在北半球和南半球，这些事件的频率、强度和羽流高度似乎都在增加。烟雾气溶胶对气候的影响可能比偶尔注入平流层的火山气溶胶大得多，因为i）它们强烈吸收阳光，这可能会影响平流层动力学；ii）它们的表面特性可能会增强它们在非均质化学和臭氧消耗中的作用。鉴于 2020 年创纪录的持续南极臭氧空洞和创纪录的北极臭氧消耗是在前所未有的野火之前发生的，因此迫切需要了解它们在气候系统中的作用。在北半球，过去五年发生了最强烈的平流层烟雾事件。 2017年，一系列遥感观测表明，太平洋西北事件（PNE）产生的烟雾在18-22公里高度持续了5个多月。 2019-2020 年，由于莱科克火山喷发产生的硫酸盐和灰烬，平流层气溶胶负荷异常高，但有证据表明 2019 年 8 月西伯利亚野火 (SIB) 的烟雾可能造成重大贡献。 2020 年春季，观测到创纪录的卤素催化北极臭氧消耗，伴随着强烈的北极极涡，其温度足以形成极地平流层云 (PSC)，直到春季为止。研究表明，如果没有《蒙特利尔议定书》减少人类消耗臭氧层物质（ODS）的排放，我们的北半球就会出现类似于南极洲的臭氧空洞。在南半球，2020 年 1 月澳大利亚“黑夏”(ABS) 野火的规模和强度都是前所未有的，数百万吨烟雾气溶胶和相关气体被注入对流层上层和平流层下层。最初的喷射高度达到了 16 公里，烟雾最终达到了 36 公里的高度（比商用跨大西洋喷气式飞机的运行高度高出三倍。上升到非常高的高度是由于存在的自升力造成的）烟雾中的黑碳（BC）吸收阳光并加热周围的空气，就像热气球一样，这种吸收阳光会导致烟雾和周围的空气明显上升，这似乎是这一单一事件造成的。 2020 年，全球平均平流层温度发生了三十年来最大的扰动，极地平流层温度创历史新低，极地涡旋极强。从卫星观测中确定的一些化学指纹表明，南极臭氧空洞非常深且持续。北极和南极创纪录的臭氧空洞都与这些野火事件有关，当人们考虑到野火的频率、强度和羽流高度时，这就变得更加令人担忧。预计在未来全球变暖的情况下会增加。可以假设，在《蒙特利尔议定书》下已经非常成功地开展的所有艰苦工作可能会被付诸东流，不是因为缺乏对消耗臭氧层物质削减的遵守，而是因为全球变暖。如果北半球出现臭氧空洞，可能会对人类赖以生存的脆弱生态系统平衡构成进一步的生存威胁。同样，平流层吸收气溶胶的动力影响可能会直接影响地球表面气候：在理想化研究中模拟了北大西洋涛动增强的正相位，这可能导致北欧洪水加剧，并可能导致伊比利亚地区发生毁灭性干旱。半岛。因此，尽早将这些因素和反馈纳入全球气候模拟至关重要。