Isotopic constraints on past ozone layer in polar ice (ISOL-ICE)

对极地冰中过去臭氧层的同位素限制（ISOL-ICE）

• 批准号: NE/N011813/1
• 负责人: Markus Frey
• 金额: $ 80.36万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN011813%2F1
• 关键词: Isotopic; constraints; past; ozone; layer

The ozone layer shields all land-based life forms from harmful ultraviolet radiation; and indirectly influences the climate at the Earth's surface, including temperature and winds, particularly near the poles. Man-made halocarbons, used for example in refrigerators and spray cans, were released to the atmosphere and have caused significant destruction of the ozone layer since the late 1970s, especially above Antarctica during spring-time. Because the use of many halocarbons was banned by the 1989 Montreal Protocol, the ozone layer is expected to recover to the conditions of the 1960s and early 1970s within this century.However, the thickness of the ozone layer is also influenced by natural causes, which are less well understood and which make predictions of future ozone and climate less certain. Natural causes include variations in the sun's activity, volcanic eruptions, release of biogenic halocarbons and atmospheric circulation. Currently there is very little information on the natural variability of the ozone layer over historic time scales, i.e. before direct observations started in the early 20th century. However, understanding the natural variability of the ozone layer and the underlying causes is necessary to evaluate the effectiveness of climate and ozone policy options. It is also necessary in order to improve predictions of ground level UV radiation, which is recognized as an environmental carcinogen and a major concern for human health.One way to go back in time beyond the era of modern measurements is the use of proxies measured in polar ice cores. Apart from a recently proposed biomarker there are no quantitative proxies of past UV radiation. Here we propose to measure the isotopes of nitrogen and oxygen in the nitrate ion in polar ice to reconstruct past ultraviolet radiation and therefore the ozone layer. Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. In the very dry regions of inner Antarctica snow is exposed to sunlight for many months before being buried by snowfall. During that exposure the nitrate in the snow is decomposed by solar UV radiation; during that process the heavier nitrogen isotopes in nitrate are observed to stay preferentially in the snow, whereas the lighter ones escape to the atmosphere above. That fractionation depends on the wavelength and duration of the UV radiation. We hypothesize that once the nitrate in snow is buried at depth, it preserves an isotopic fingerprint of down-welling UV radiation and therefore of the thickness of the ozone layer.We propose to collect a shallow ice core from East Antarctic Plateau, where low accumulation rates prevail, to develop and apply a new ice core proxy based on the stable isotopes of nitrate, to constrain trends in the ozone layer above Antarctica over the last 1kyr. To do this, we will calibrate the ice core signal with observations of the ozone layer above Antarctica since the 1950s, and then extrapolate that relationship to the more distant past.Using numerical models we will investigate the underlying causes of the ice core based reconstruction of past variability in the ozone layer. Particular questions we will attempt to answer include: has stratospheric ozone changed in the past; and how did solar variability, natural emissions of halocarbons, or volcanic eruptions contribute to the reconstructed trends?

臭氧层保护所有陆地生命形式免受有害的紫外线辐射；并间接影响地球表面的气候，包括温度和风，特别是在两极附近。自 20 世纪 70 年代末以来，冰箱和喷雾罐中使用的人造卤化碳被释放到大气中，对臭氧层造成了严重破坏，特别是在春季的南极洲上空。由于许多卤代烃的使用被1989年《蒙特利尔议定书》禁止，臭氧层有望在本世纪内恢复到1960年代和70年代初的状况。然而，臭氧层的厚度也受到自然原因的影响，人们对这些现象的了解还较少，这使得对未来臭氧和气候的预测变得不太确定。自然原因包括太阳活动的变化、火山爆发、生物卤化碳的释放和大气环流。目前，关于臭氧层在历史时间尺度上自然变化的信息非常少，即在 20 世纪初开始直接观测之前。然而，了解臭氧层的自然变化及其根本原因对于评估气候和臭氧政策选择的有效性是必要的。为了改进对地面紫外线辐射的预测也是必要的，地面紫外线辐射被认为是一种环境致癌物，也是人类健康的一个主要问题。追溯现代测量时代之后的一种方法是使用以极地冰芯。除了最近提出的生物标记之外，没有过去紫外线辐射的定量替代指标。在这里，我们建议测量极地冰中硝酸根离子中的氮和氧同位素，以重建过去的紫外线辐射，从而重建臭氧层。同位素是具有相同质子数但中子数不同的同一元素的原子。在南极洲内陆非常干燥的地区，雪在被降雪掩埋之前会暴露在阳光下数月之久。在暴露期间，雪中的硝酸盐被太阳紫外线辐射分解；在此过程中，观察到硝酸盐中较重的氮同位素优先留在雪中，而较轻的氮同位素则逃逸到上方的大气中。该分级取决于紫外线辐射的波长和持续时间。我们假设，一旦雪中的硝酸盐被深埋，它就会保留下流紫外线辐射的同位素指纹，从而保留臭氧层厚度的同位素指纹。我们建议从东部南极高原收集浅冰芯，那里的积累量较低率占主导地位，开发和应用基于硝酸盐稳定同位素的新冰芯代理，以限制过去 1 年内南极洲上空臭氧层的趋势。为此，我们将通过自 20 世纪 50 年代以来对南极洲上空臭氧层的观测来校准冰芯信号，然后推断出与更遥远的过去的关系。使用数值模型，我们将研究基于冰芯重建的根本原因。臭氧层过去的变化。我们将尝试回答的具体问题包括：平流层臭氧在过去是否发生过变化？太阳变化、卤化碳的自然排放或火山喷发如何影响重建的趋势？

项目成果

New insights into the atmospheric oxidising capacity above the Antarctic Plateau

对南极高原上方大气氧化能力的新见解

• 发表时间: 2018
• 作者: Frey M. M.

Chemistry in the Cryosphere - (In 2 Parts)

冰冻圈化学 -（分 2 部分）

• DOI: 10.1142/9789811230134_0017
• 发表时间: 2022
• 作者: Miller L

Increasing Accumulation of Perfluorocarboxylate Contaminants Revealed in an Antarctic Firn Core (1958-2017).

• DOI: 10.1021/acs.est.2c02592
• 发表时间: 2022-08-16
• 期刊: ENVIRONMENTAL SCIENCE & TECHNOLOGY
• 影响因子: 11.4
• 作者: Garnett, Jack;Halsall, Crispin;Winton, Holly;Joerss, Hanna;Mulvaney, Robert;Ebinghaus, Ralf;Frey, Markus;Jones, Anna;Leeson, Amber;Wynn, Peter
• 通讯作者: Wynn, Peter

The TropD software package (v1): standardized methods for calculating tropical-width diagnostics

• DOI: 10.5194/gmd-11-4339-2018
• 发表时间: 2018-10-26
• 期刊: GEOSCIENTIFIC MODEL DEVELOPMENT
• 影响因子: 5.1
• 作者: Adam, Ori;Grise, Kevin M.;Ming, Alison
• 通讯作者: Ming, Alison

Summer variability of the atmospheric NO 2 : NO ratio at Dome C on the East Antarctic Plateau

东南极高原 Dome C 大气 NO 2 : NO 比值的夏季变化

• DOI: 10.5194/acp-22-12025-2022
• 发表时间: 2022
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: Barbero A