Calibration and Analysis of Mount Wilson Magnetograms and Dopplergrams for the Years 1967 to 2013

1967年至2013年威尔逊山磁图和多普勒图的校准和分析

• 批准号: 2000994
• 负责人: Roger Ulrich
• 金额: $ 29.59万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2000994&HistoricalAwards=false
• 关键词: Calibration; Analysis; Mount; Wilson; Magnetograms

The Sun influences the Earth and its environment in a large range of phenomena, such as aircraft radiation levels, atmospheric drag on spacecraft, long-distance power transmission, pipeline charging and radio communication (especially at high latitudes), etc. Severe solar storms can disrupt global communications and damage spacecraft. These effects have been detailed in "Committee on the Societal and Economic Impacts of Severe Space Weather Events: A Workshop, National Research Council (2008)," and are further discussed in "Committee on a Decadal Strategy for Solar and Space Physics (Heliophysics): National Research Council (2013)." The most recent solar cycle 24 was of relatively low strength, and the upcoming cycle 25 is beginning slowly. Cosmic ray records, as recovered by proxy indicators, suggest that the solar cycle goes through long periods of strength and weakness lasting one or more centuries, which are called grand maxima and grand minima. In the past few decades, there has been considerable progress in understanding the mechanisms governing the Sun's magnetic cycle. In this process, comparisons between model output, including predicted cycle variability and the observed characteristics of the solar cycle, is an essential step in the validation of the models. This 3-year research project is aimed at increasing the number of available solar cycles from four to five by carrying out a new calibration process of the unique magnetogram data gathered by the Mount Wilson Observatory (MWO), thus improving their quality for further use by the broader solar-heliospheric community.The MWO, under the direction of G.E. Hale and H.W. Babcock, pioneered in the discovery and measurement of solar surface magnetic fields. From 1964 to 1985, under the direction of R.F. Howard, the visible solar disk magnetic fields were measured and digitally recorded on magnetic tape. The PI of this project, R.K. Ulrich, managed the program from 1986 to 2013. The full digital record spans 46 years, or about four solar cycles. For the years 1967 to 1973, a major part of solar cycle 20, no other set of regular magnetic field measurements is available. In April 1973 a program of daily magnetogram observations was started at the Kitt Peak National Observatory, and in May 1975 daily observations began at the Stanford Solar Observatory, now the Wilcox Solar Observatory (WSO), with data from space-based systems becoming available in 1995. All these data series, except that from the MWO, continue today. During this 3-year project, the PI will carry out a new calibration of the MWO magnetogram and Dopplergram series, which will take into account various changes in the instrument hardware, calibration data acquisition methods and software reduction methods. Initial analysis of the magnetograms from 1967-1969 shows that there are significant irregularities in the nominal calibration process. Also, all the magnetogram measurements depend on complex spectral line formation processes so that the derived fields are different for each of the series referenced above and, within each series, across jumps due to instrument and calibration changes. The resulting dataset of magnetograms consistently calibrated over an extended period of time is important for cross-calibrating (and identifying systematics in) the magnetic field measurements taken with other instruments during the same period of time. The use of solar surface magnetograms is required for the calculation and prediction of conditions in the heliosphere. An "Open Magnetic Field Flux Problem" has been noted in several studies, so that the calibration and interpretation of the magnetogram observations has become a central issue. This project will address this issue following up on the work carried out previously by the project team. The data products from various stages of the recalibration, including the final, best result will be retained and made available to the community and public through partnership with the Stanford Helioseismology Archive which is part of the JSOC system at Stanford University. The project team will work with the broader solar community to incorporate the MWO magnetograms into the ADAPT/WSA pipeline, which yields predicted properties of the solar wind. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.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.

太阳通过多种现象影响地球及其环境，如飞机辐射水平、大气对航天器的拖累、远距离输电、管道充电和无线电通信(特别是在高纬度地区)等。严重的太阳风暴可以扰乱全球通信，损坏航天器。这些影响在“严重空间天气事件的社会和经济影响委员会：国家研究理事会讲习班”(2008年)中有详细论述，并在“太阳和空间物理十年战略委员会：国家研究理事会”(2013年)中作了进一步讨论。最近的第24个太阳周期的强度相对较低，而即将到来的第25个太阳周期正在缓慢开始。由代理指标恢复的宇宙射线记录表明，太阳周期经历了长达一个或多个世纪的强弱时期，这被称为大极大和大极小。在过去的几十年里，在理解控制太阳磁周期的机制方面取得了相当大的进展。在这一过程中，模型输出之间的比较，包括预测的太阳周期变率和观测到的太阳周期特征，是验证模型的一个重要步骤。这项为期3年的研究项目旨在通过对威尔逊山天文台(MWO)收集的独特磁图数据进行新的校准过程，将可用太阳周期从4个增加到5个，从而提高其质量，供更广泛的太阳-日球层社区进一步使用。MWO在G.E.Hale和H.W.Babcock的指导下，率先发现和测量太阳表面磁场。从1964年到1985年，在R.F.Howard的指导下，测量了可见的太阳圆盘磁场，并将其数字化记录在磁带上。该项目的主要负责人R.K.乌尔里希在1986至2013年间负责管理该项目。整个数字记录的时间跨度为46年，即大约四个太阳周期。从1967年到1973年，太阳周期第20周的主要部分，没有其他常规的磁场测量数据。1973年4月，基特峰国家天文台启动了每日磁图观测计划，1975年5月，斯坦福太阳天文台，即现在的威尔科克斯太阳天文台(WSO)开始进行每日观测，1995年开始提供天基系统的数据。所有这些数据系列，除了来自MWO的数据，今天都在继续。在这个为期三年的项目中，PI将对MWO磁图和多普勒图系列进行新的校准，这将考虑到仪器硬件、校准数据获取方法和软件还原方法的各种变化。对1967-1969年磁图的初步分析表明，在标称校准过程中存在明显的不规则性。此外，所有磁图测量都依赖于复杂的谱线形成过程，因此对于上述每个系列，导出场是不同的，并且在每个系列中，由于仪器和校准的变化而跨越跳跃。在一段较长的时间内一致校准的结果磁图数据集对于交叉校准(和确定系统学)在同一时间段内用其他仪器进行的磁场测量很重要。需要使用太阳表面磁图来计算和预测日光层的条件。在一些研究中发现了一个“开放磁场通量问题”，因此磁图观测的校准和解释已成为一个中心问题。该项目将在项目组以前开展的工作的基础上解决这一问题。将保留重新校准各个阶段的数据产品，包括最终的最佳结果，并通过与斯坦福大学日震学档案馆的伙伴关系向社区和公众提供，斯坦福日震学档案馆是斯坦福大学JSOC系统的一部分。该项目团队将与更广泛的太阳能社区合作，将MWO磁图纳入ADAPT/WSA管道，该管道将产生预测的太阳风特性。该项目的研究和EPO议程支持AGS部门在发现、学习、多样性和跨学科研究方面的战略目标。该奖项反映了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。