Greenwich Magnetic Observatory Magnetograms

Magnetograms are records of variations in the strength and direction of the Earth’s magnetic field. Historically these magnetograms were recorded on paper using photographic techniques. In the UK, measurements were made at eight long-running observatories; Abinger, Eskdalemuir, Falmouth, Greenwich, Hartland, Kew, Lerwick, and Stonyhurst. BGS also hold magnetogram records from the Cape Evans observatory that ran continuously at Robert Falcon Scott’s Antarctic base camp during the British Antarctic Expedition 1910–13. The magnetogram collection, one of the longest running geomagnetic series in the world, provides a continuous record of more than 160 years of UK measurements. These magnetograms start in the 1840s and end in 1986 at which time digital recording of the magnetic field took over and magnetograms can be produced by computer graphic. The plots show variation in the Earth's magnetic field, typically over a 24-hour period. The collection is a valuable, partly untapped data resource for studying geomagnetic storms, space weather and the evolution of the Earth’s magnetic field. The magnetograms provide insight into: • the Earth’s outer core: long-term change (years to centuries) in the dynamo that sustains our magnetic field • space weather: short-term changes (seconds to days) in near-Earth space and on the ground • space climate: long-term change (decades to centuries) in solar activity and consequences for Earth’s environment All the above have an impact on human activities. For example, bad space weather affects technologies that we increasingly rely on, such as electrical power and GPS networks. In response to the threat of loss from degradation due to age and a desire to preserve and exploit old data, BGS undertook a programme of work to digitally photograph, archive and preserve the analogue paper records of magnetic field variation in the United Kingdom. Between 2009 and 2013, high-quality digital images of every available magnetogram were taken. These images are available to search online. Scientists and the general public around the world can now gain easy access to this historical dataset.地磁图（magnetograms）是记录地球磁场强度与方向变化的观测记录。历史上，这类地磁图曾通过摄影技术记录于纸质介质之上。在英国境内，共有8个长期运行的地磁观测台开展相关地磁测量，分别为阿宾格（Abinger）、埃斯代尔缪尔（Eskdalemuir）、法尔茅斯（Falmouth）、格林威治（Greenwich）、哈特兰（Hartland）、邱园（Kew）、勒威克（Lerwick）以及斯托尼赫斯特（Stonyhurst）。英国地质调查局（British Geological Survey, BGS）还馆藏有来自埃文斯角观测台（Cape Evans observatory）的地磁图记录，该观测台曾在罗伯特·法尔肯·斯科特（Robert Falcon Scott）领导的1910-1913年英国南极探险队期间，于南极大本营持续运行。 该地磁图馆藏是全球持续运行时间最长的地磁序列数据集之一，收录了英国跨度逾160年的连续地磁测量记录，其时间起点为19世纪40年代，终止于1986年——自彼时起，地球磁场的记录方式转为数字化，地磁图亦可通过计算机图形技术生成。这类图表通常用于展示地球磁场的日变化特征。本馆藏是极具价值且尚未得到充分挖掘的数据资源，可用于地磁暴、空间天气以及地球磁场演化等领域的研究。 地磁图能够为以下研究提供重要科学参考： • 地球外核：维持地球磁场的地磁发电机效应的长期变化（时间尺度为数年至数百年） • 空间天气：近地空间与地面环境的短期变化（时间尺度为数秒至数天） • 空间气候：太阳活动的长期变化（时间尺度为数十年至数百年）及其对地球环境的影响 上述所有研究方向均与人类活动息息相关。例如，恶劣空间天气会对人类日益依赖的技术系统造成干扰，包括电力网络与全球定位系统（Global Positioning System）等。 为应对纸质模拟记录因老化退化而面临的丢失风险，同时出于保存与开发利用历史数据的需求，英国地质调查局（BGS）启动了一项专项工作，对英国境内的纸质模拟地磁变化记录开展数字化摄影、归档与保存。2009年至2013年间，工作人员对所有可获取的地磁图完成了高清数字化拍摄。这些数字化图像支持在线检索，全球范围内的科研人员与普通公众如今均可便捷获取这一历史数据集。