This database documents the short-term and long-term fluctuations in the Earth's regional (New Zealand) magnetic field captured by magnetic observatories. Magnetic Observatories record variations with time of the earth’s magnetic field at a fixed point. A magnetic field is completely described by three components, these are usually HDZ or XYZ, where H is the horizontal magnetic field strength, D is the declination or angle between the direction of the magnetic field and true north, Z is the vertical magnetic strength, and X and Y are the magnetic field strengths in the true north and east directions. It is also common to record F, the total magnetic field strength, on a separate instrument, although that can be calculated from HDZ or XYZ. New Zealand operates magnetic observatories in Canterbury (the Eyrewell Geomagnetic Observatory that succeeded the Christchurch and Amberley observatories and is now located at West Melton) and Scott Base in Antarctica, and supports the Apia observatory in Samoa. Eyrewell (EYR), Scott Base (SBA) and Apia (API) geomagnetic observatories are important contributors to the ~120 station INTERMAGNET global network that monitors the Earth’s magnetic field. All observatories follow INTERMAGNET requirements and standards. The continuous part of the data collection is run by an automated system that is recording data every second. Manual measurements are conducted by a local observer for 1 hour once every week. EYR also relies on data recorded at a joined GeoNet site located at Summerhill (Canterbury). Raw 1-second data in miniseed format is archived for all three observatories plus for the Summerhill site. Preliminary 1-second and 1-minute data are submitted to INTERMAGNET in a standardized file format every hour. Definitive 1-minute data for EYR, SBA and API is being submitted to INTERMAGNET annually. Before INTERMAGNET definitive data are being published an international multi-step reviewing process is being applied to ensure international standards are being met. K-index values are calculated from data recorded at EYR and its predecessor Amberley (AML). Historic paper records are being stored, with some of them being scanned into digital images.

Annual mean values (yearmean.eyr) since 1902. Annual reports (or yearbooks) for Christchurch Magnetic Observatory and Amberley Magnetic Observatory providing more information (metadata) around the data recordings. Link to EYR k-index values https://data.gns.cri.nz/metadata/srv/eng/catalog.search#/metadata/d9ff1898-f1ea-4e69-a533-82e730708264 DOI: https://doi.org/10.21420/5WPF-SB23 Cite data as: GNS Science. (2022). Amberley (AML) and Eyrewell (EYR) supplementary data [Data set]. GNS Science. https://doi.org/10.21420/5WPF-SB23

The dataset is composed of the original sheets on which the fields were recorded by light on photographic paper. Each magnetogram sheet holds a record of 24 hours. Normally the magnetic field components H and D are recorded; some years in addition do have recordings of the Z component. Apia (API) 1907 – 1913 Apia (API) 1932 – 1955 There are magnetograms for 1956 - 1994, but they are not complete and the contents need yet to be specified. For 1907 - 1913, magnetograms for H and D are mostly complete. The years 1908 - 1911 have some additional magnetograms that might be for the Z component. GNS Science does not hold records from 1914 to 1931. After the long gap, there are fewer magnetograms for 1932 - 1936; from 1937 - 1955, each year has magnetograms for H, D & Z for most days. There are Apia rapid runs available for 1956 - 1978, and 1983-1986, and Apia Wider Range (WR) from 1977, 1979, 1980, 1983, 1985, 1986. Some of the records were received from the University of Göttingen, Germany, who originally established this magnetic station. DOI: https://doi.org/10.21420/WYV2-6K33 Cite as: GNS Science. (2022). Apia (API) paper magnetograms . GNS Science. https://doi.org/10.21420/WYV2-6K33

The dataset is composed of the original sheets on which the fields were recorded by light on photographic paper. Each sheet holds 24 hours of three recorded magnetic field components. Most of the components were labelled XYZ; some were labelled DHZ (e.g. 1991 magnetograms), and others were not labelled at all (e.g. 1966 magnetograms). Scott Base (SBA) 1957 – 1991 DOI: https://doi.org/10.21420/3KT9-3M51 Cite as: GNS Science. (2022). Scott Base (SBA) paper magnetograms . GNS Science. https://doi.org/10.21420/3KT9-3M51

Nearly 22,000 paper magnetograms were scanned into images by New Zealand Micrographic Services (NZMS) in 2021-2022. The formats are .jpg and .tiff. The scanning was done in greyscale, at 600dpi, and the original ratio was preserved. Monthly contact sheets as a preview option are available. Amberley (AML) 1919 - 1977 Eyrewell (EYR) 1978 – 1991 DOI: https://doi.org/10.21420/ZN6T-QZ22 Cite data as: GNS Science. (2022). Amberley (AML) and Eyrewell (EYR) scanned magnetograms [Data set]. GNS Science. https://doi.org/10.21420/ZN6T-QZ22

This database documents fluctuations in the Earth's regional (New Zealand) magnetic field measured before the age of digital records. New Zealand operates magnetic observatories in Canterbury (the Eyrewell Geomagnetic Observatory located at West Melton) and Scott Base in Antarctica, and supports the Apia observatory in Samoa. Observatories in the present days provide a record of temporal changes of the magnetic field, recording the three components of the magnetic field every second. Eyrewell (EYR), Scott Base (SBA) and Apia (API) geomagnetic observatories.

The dataset is composed of the original sheets on which the fields were recorded by light on photographic paper. Normally one sheet holds the record from three magnetic field components, HDZ or XYZ, for 24 hours, sometimes with a record of temperature used to make instrumental corrections. Amberley (AML) 1919 - 1977 Eyrewell (EYR) 1978 – 1991 There is no overlap between Amberley and Eyrewell paper magnetograms. The very last paper magnetogram for EYR was recorded on 27 May 1991. The digital recording at EYR started on 29 June 1990 (sampling rate: 20 seconds). GNS Science have 20-second EYR pre-INTERMAGNET data available until they started to publish Definitive 1-minute Eyrewell (EYR) data via INTERMAGNET on 1 January 1994. DOI: https://doi.org/10.21420/F3JE-C208 Cite as: GNS Science. (2022). Amberley (AML) and Eyrewell (EYR) paper magnetograms . GNS Science. https://doi.org/10.21420/F3JE-C208