A Unified Sunspot Group Dataset (RGO/SOON/NOAA ) from 1874 to Present

The Royal Greenwich Observatory (RGO) compiled sunspot observations from a small network of observatories to produce a dataset of daily observations starting in May of 1874. The observatory concluded this dataset in 1976 after the US Air Force (USAF) started compiling data from its own Solar Optical Observing Network (SOON). This work was continued with the help of the US National Oceanic and Atmospheric Administration (NOAA) with much of the same information being compiled through to the present. Unfortunately, the more recent data is given in a different format from the original and there are definite changes in the reported parameters from the different sources. In an effort to append the RGO data with the more recent data David Hathaway has reformated the USAF and NOAA data to conform to the older RGO data format. The entire dataset is available below as ASCII text files containing records for individual years. Each file consists of records with information on individual sunspot groups for each day that spots were observed.Careful inspection of the data indicates that quantities such as sunspot area are not uniform across datasets or even within a given dataset. For example, the ratio of the umbral areas (the darker part of the sunspot) to total spot area (including the lighter penumbra) changes abruptly in 1941/1942 and the ratio of the total sunspot area to the sunspot number changes dramatically with the start of the USAF/NOAA data. In an effort to correct for these variations I have compared this data with the more uniform data compiled by Howard, Gilman, and Gilman (ApJ 283, 373, 1984) for the Mount Wilson photographic plate collection from 1917 to 1982. This comparison shows three epochs for the reported sunspot areas: for 1917-1941 Mt. Wilson Umbral Area = 0.35 RGO Umbral Area and Mt. Wilson Spot Area = 0.067 RGO Spot Area; for 1942-1968 Mt. Wilson Umbral Area = 0.41 RGO Umbral Area and Mt. Wilson Spot Area = 0.067 RGO Spot Area; for 1969-1981 Mt. Wilson Umbral Area = 0.59 RGO/USAF/NOAA Umbral Area and Mt. Wilson Spot Area = 0.094 RGO/USAF/NOAA Spot Area.In producing the butterfly diagram (86 kb png) (showing total sunspot area as a function of time and latitude) David Hathaway has retained the RGO Spot Areas prior to 1977 as reported but increased the USAF/NOAA Spot Areas by a factor of 1.4 after 1976. The data plotted in the Butterfly Diagram is contained in a (453KB ASCII text file) with a single record containing the Carrington rotation number followed by five records containing 10 values each of the total sunspot area (in units of millionths of a hemisphere) found in 50 latitude bins distributed uniformly in Sine(latitude). Data Description This Dataset contains the yearly RGO and USAF/NOAA data files. A list of corrections and updates to this database can be found here.The data format is given in attached format.txt and can be also found here (data format). The series of data files from 1874-2024 are also available in a single 5 Mb ZIP file. Text files containing the monthly averages of the daily sunspot areas (again in units of millionths of a hemisphere) are also available for the full sun, the northern hemisphere, and the southern hemisphere. Another text file contains (daily sunspot areas) (1.51 Mb). These derived data include the correction factor of 1.4 for data after 1976. The missing days within the dataset are indicated by sunspot area values of -1 in the daily sunspot area file. The yearly RGO and USAF/NOAA data files are here. For Further Detail Visit: solarcyclescience.com皇家格林尼治天文台（Royal Greenwich Observatory, RGO）汇编了小型观测台网的太阳黑子（sunspot）观测资料，构建了一套始于1874年5月的每日观测数据集。该天文台于1976年停止该数据集的编撰工作，彼时美国空军（United States Air Force, USAF）已启动其自主的太阳光学观测网络（Solar Optical Observing Network, SOON）的数据采集工作。后续的数据编撰工作由美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）承接，沿用大部分原有信息体系并延续至今。 遗憾的是，较新的观测数据采用了与原始数据集不同的格式，且不同来源的报告参数存在明确差异。为将最新数据整合至RGO原始数据集中，大卫·哈撒韦（David Hathaway）将USAF与NOAA的数据重新格式化，使其与RGO旧有数据格式保持一致。 整套数据集以ASCII文本文件形式提供，按年份拆分存储，每个文件包含观测到太阳黑子的每日记录，每条记录对应单日的单个太阳黑子群（sunspot group）信息。 对数据的细致检视表明，太阳黑子面积等量化指标在不同数据集间，甚至在同一数据集内部均存在不一致性。例如，本影（umbra，太阳黑子的暗黑核心区域）与黑子总面积（包含较亮的半影（penumbra）区域）的比值在1941/1942年发生突变；而太阳黑子总面积与黑子数的比值，在USAF/NOAA数据启动后出现了显著变化。 为校正这些系统性偏差，研究者将本数据集与霍华德（Howard）、吉尔曼（Gilman）及吉尔曼（Gilman）于1984年发表于《天体物理学杂志》（Astrophysical Journal, ApJ）283卷373页的均匀数据集进行了对比。该数据集基于1917年至1982年的威尔逊山天文台照相底片归档资料。对比结果将报告的太阳黑子面积划分为三个阶段： 1. 1917-1941年：威尔逊山本影面积 = 0.35 × RGO本影面积，威尔逊山黑子总面积 = 0.067 × RGO黑子总面积； 2. 1942-1968年：威尔逊山本影面积 = 0.41 × RGO本影面积，威尔逊山黑子总面积 = 0.067 × RGO黑子总面积； 3. 1969-1981年：威尔逊山本影面积 = 0.59 × RGO/USAF/NOAA本影面积，威尔逊山黑子总面积 = 0.094 × RGO/USAF/NOAA黑子总面积。 在制作太阳黑子蝴蝶图（butterfly diagram，86 KB PNG格式，展示太阳黑子总面积随时间与纬度的分布）时，大卫·哈撒韦保留了1977年之前的RGO原始报告的黑子总面积数据，并将1976年之后的USAF/NOAA黑子总面积数据放大了1.4倍。蝴蝶图所用数据存储于一个453 KB的ASCII文本文件中，文件首条记录为卡林顿自转周（Carrington rotation）编号，后续五条记录各包含10个数值，分别对应以半球百万分之一为单位的太阳黑子总面积，分布于按正弦纬度均匀划分的50个纬度区间内。 数据集说明 本数据集包含1874年至2024年的年度RGO与USAF/NOAA数据文件。该数据库的修正与更新列表可在此处查阅。数据格式详见附件format.txt，亦可在此处获取（数据格式说明）。1874-2024年的全套数据文件已打包为单个5 MB的ZIP压缩包供下载。此外还提供了按月份统计的每日太阳黑子面积平均值（单位仍为半球百万分之一），涵盖全球、北半球与南半球三个维度。另有一个1.51 MB的文本文件包含每日太阳黑子面积数据，该衍生数据集已针对1976年之后的数据应用了1.4倍的校正系数。当日缺失的观测数据在每日黑子面积文件中以-1标记。年度RGO与USAF/NOAA数据文件可在此处获取。 如需进一步详情，请访问：solarcyclescience.com