Solar Eclipse-Induced Changes in the Ozone Layer Observed with UV/VIS (UltraViolet–VISible Spectroscopy) Radiometer

日食是一种罕见的天文现象，它为探测地球大气中发生的过程提供了一个天然的实验平台。据报道，在日食期间，月球的阴影在我们的星球上运行时将导致臭氧层的波动，这一结果是有争议的，需要额外的新研究。地球的臭氧层保护地球上的生命免受太阳有害的紫外线辐射。该项目通过使用两种不同的仪器测量2024年4月8日日全食期间的“总臭氧”（从地球表面到大气顶部的臭氧总量）和太阳紫外线辐射，努力解决这一问题。该项目的结果将提高我们对太阳辐射穿过大气层到达地球表面的方式的理解，在那里它与生物世界相互作用。除了对这种“辐射转移”提供新的见解外，该项目还将有助于人类更好地了解日食这一令人敬畏的现象及其影响。此外，该项目将提高一名国际研究生的学术技能，他将模拟日全食期间的辐照度，并将其与测量结果进行比较。墨西哥的观察员和来自德国的科学家在不增加项目费用的情况下参与促进了国际合作。众所周知，当月球的影子以超音速在地球上空移动时，日食会在上层大气（电离层）中产生重力波。然而，对平流层臭氧层的影响还没有得到很好的证实，一些出版物支持这种联系，一些出版物对这种联系提出了质疑，还有一些出版物由于测量误差而提出了模棱两可的结果。该项目的首要目标是通过在2024年4月8日日全食期间使用“全球”（太阳和天空）和太阳直射（UV）范围内测量总臭氧柱（TOC）的短期（秒到分钟）变化来解决这些矛盾。测量将在墨西哥Mazatlán的日全食路径下进行。在这个位置，日全食将持续4分25秒，晴天的可能性是日食路径上最高的天空之一。将使用GUVis-3511辐射计进行全球观测，该辐射计使用305至1640 nm之间的19个波段；TOC是从305和340 nm之间的测量计算出来的。辐射计配备了阴影带，以便交替进行全球和漫射测量，从而计算直接光谱辐照度。MICROTOPS II太阳光度计也将用于太阳直射观测。使用两种不同的仪器减少了由测量伪影引起的TOC观测变化被错误地归因于实际臭氧变化的风险。作为该项目的一部分收集的数据将提高对高层大气和平流层之间耦合的理解。除了TOC观测外，地球表面的全球光谱辐照度在日全食期间的测量结果将与三维辐射传输模型的结果进行比较。这将增强对日食期间光子传输的理解，在日食期间，光子进入月球阴影外的大气，在到达观测者之前会被散射多次，这是一个具有数值挑战性的问题。2017年日食期间的类似比较扩大了我们对表面反照率、地形、气溶胶和垂直臭氧分布对光子路径的影响的了解。2024年日食期间记录的数据将进一步加深我们对这一重要影响的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Solar eclipses are rare astronomical phenomena, which provide a natural testbed for probing processes occurring in Earth’s atmosphere. It has been reported that the Moon’s shadow as it travels over our planet during an eclipse will lead to fluctuations in the ozone layer, a result which is controversial and demands additional new research. The Earth’s ozone layer protects life on our planet from the Sun’s harmful ultraviolet (UV) radiation. This project strives to resolve this issue by performing measurements of “total ozone” (ozone amounts integrated from the Earth’s surface to the top of the atmosphere) and solar UV radiation during the total solar eclipse of 8 April 2024 with two distinct instruments. Results from the project will improve our understanding about the way radiation from the Sun travels through the atmosphere to Earth’s surface where it interacts with the living world. Apart from providing new insights in this "transfer of radiation", the project will contribute to the desire of mankind to better understand the awe-inspiring phenomenon of a solar eclipse and its implications. Furthermore, the project will advance the academic skills of an international graduate student who will simulate the irradiance during totality and compare it with the measurements. Participation of observers in Mexico and scientists from Germany at no additional costs to the project promote international collaborations.It is well established that solar eclipses generate gravity waves in the upper atmosphere (ionosphere) as the Moon’s shadow travels at supersonic speeds over Earth. However, effects on the stratospheric ozone layer are less well established, with some publications supporting a link, some disputing one, and some presenting ambiguous results because of measurement artifacts. The overarching objective of this project is to resolve these contradictions by measuring short-term (seconds to minutes) variations in the total ozone column (TOC) using “global” (Sun and sky) and direct-Sun observations in the ultraviolet (UV) range during the total solar eclipse of 8 April 2024. Measurements will be performed at Mazatlán, Mexico, under the path of totality. At this location, totality will last 4 minutes and 25 seconds and the likelihood of clear skies is one of the highest along the path of the eclipse. Global observations will be made with a GUVis-3511 radiometer, which uses 19 wavebands between 305 and 1640 nm; TOC is calculated from measurements between 305 and 340 nm. The radiometer is equipped with a shadow band to allow alternating global and diffuse measurements from which the direct spectral irradiance is calculated. A MICROTOPS II sun photometer will also be used for direct-Sun observations. Use of two distinct instruments reduces the risk that observational variations in TOC caused by measurement artifacts are incorrectly attributed to real ozone changes. Data collected as a part of this project will improve the understanding of the coupling between the upper atmosphere and the stratosphere. In addition to TOC observations, measurements of the global spectral irradiance during totality at the Earth’s surface will be compared with results of a 3-D radiative transfer model. This will enhance understanding of photon transport during a solar eclipse where photons entering the atmosphere outside the Moon’s shadow are scattered many times before reaching the observer, which is a numerically challenging problem to solve. A similar comparison during the 2017 eclipse has expanded our knowledge of the effects of surface albedo, topography, aerosols, and the vertical ozone distribution on the photon path. Data recorded during the 2024 eclipse will increase our understanding of this important effect further.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.