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自然的试验台。据报道，月食期间月球的阴影会导致臭氧层的波动，这一结果是有争议的，需要进行更多的新研究。地球的臭氧层保护地球上的生命免受太阳有害的紫外线(UV)辐射。该项目致力于解决这一问题，方法是使用两台不同的仪器测量2024年4月8日日全食期间的“臭氧总量”(从地球表面到大气层顶部的臭氧总量)和太阳紫外线辐射。该项目的结果将提高我们对太阳辐射如何穿过大气到达地球表面的理解，在那里它与生物世界相互作用。除了为这一“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，他将模拟整个过程中的辐照度，并将其与测量结果进行比较。墨西哥的观察员和德国的科学家在不增加该项目费用的情况下参与该项目，促进了国际合作。众所周知，日食会在月球阴影以超音速在地球上空传播时，在高层大气(电离层)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，一些出版物支持一种联系，一些出版物有争议，一些出版物由于测量误差而给出了模棱两可的结果。该项目的总体目标是解决这些矛盾，方法是在2024年4月8日的日全食期间，利用“全球”(太阳和天空)和紫外线(UV)范围内的太阳直射观测，测量臭氧总量(TOC)的短期(秒至分钟)变化。测量将在墨西哥马萨特兰进行，在全食路径下进行。在这个位置，日全食将持续4分25秒，晴朗天空的可能性是沿日食路径最高的之一。全球观测将使用GUVis-3511辐射计，它使用305到1640 nm之间的19个波段；总有机碳是根据305到340 nm之间的测量结果计算出来的。辐射计配备了阴影带，以允许交替进行全局和漫反射测量，根据这些测量可以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降低了由测量伪影引起的总有机碳观测变化被错误地归因于真实臭氧变化的风险。作为该项目的一部分收集的数据将增进对高层大气和平流层之间耦合的了解。除了总有机碳观测外，还将把对地球表面整体光谱辐照度的测量结果与三维辐射传输模型的结果进行比较。这将加强对日食期间光子传输的理解，在日食期间，进入月球阴影外的大气的光子在到达观测者之前被多次散射，这在数值上是一个需要解决的问题。2017年日食期间的类似比较扩大了我们对地表反照率、地形、气溶胶和臭氧在光子路径上的垂直分布的影响的了解。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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.