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.

Preliminary 1-second and 1-minute Apia (API) data are submitted to INTERMAGNET in a standardized file format (IAGA-2002) every hour. The data can be downloaded via a free web access provided by INTERMAGNET at http://www.intermagnet.org/data-donnee/download-eng.php (Data Type: ‘provisional’). 1-minute (Sample Rate: ‘minute’) ‘provisional’ API data are available since 1999. 1-second data (Sample Rate: ‘second’) ‘provisional’ API data are available since 2012. DOI: https://doi.org/10.21420/7NXY-T568 Cite data as: GNS Science, & MNRE Samoa. (2022). Preliminary 1-second and 1-minute Apia (API) data [Data set]. INTERMAGNET.

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.

Continuous data recorded by New Zealand's Geomagnetic Observatories EYR, SBA & API processed at 1-minute sampling and baseline (absolute values) corrected. The data for each observatories is being submitted to INTERMAGNET annually (submitted by July 1st for the previous year’s data Jan 1 to 31 Dec). EYR data since 1-Jan-1994 SBA data since 1-Jan-1996 API data since 1-Jan-1999 Before the definitive data for each year is being published via INTERMAGNET an international multi-step reviewing process is being applied to ensure international standards are being met.

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

K-index values calculated from Amberley (AML) and Eyrewell Geomagnetic Observatory (EYR) data. The K-index is a measure of disturbances in the Earth’s magnetic field which was introduced by Bartels et al. (1939), that is recognised as a good indication of the strength of magnetic storm activity caused by the sun. It is based on the maximum fluctuations of horizontal components recorded in each 3-hour interval, so there are eight values each day. The scale is from 0 to 9, in an approximately logarithmic fashion, with the nT value required for the maximum value of 9 being a parameter of the observatory. Originally the fluctuations were measured on paper chart records, measuring short-term variations by subtracting the effects of the slower daily variations, but with digital records, algorithms are used to calculate only the effects of short-term variations. At Eyrewell, the manual method was used up until 1995, while from 1996 onwards, an algorithm developed by Hattingh et al (1989) at the Hermanus Magnetic Observatory was used (Tomlinson, 1995). The Hemanus algorithm is available from the website http://isgi.unistra.fr/softwares.php. Available data: Amberley (AML) 1951 – 1977 Eyrewell (EYR) 1978 – present 1932 – 1977 planetary Kp values (https://www.gfz-potsdam.de/en/kp-index/) were produced based on data from the Amberley observatory as a representative for the Southern Hemisphere. Toolangi only joined in 1972 (and was replaced by Canberra in 1981). DOI: https://doi.org/10.21420/PJ1Y-6M90 Cite as: GNS Science, & Hurst , T. (2021). EYR k-index values [Data set]. GNS Science. https://doi.org/10.21420/PJ1Y-6M90

Continuous data recorded by New Zealand's Geomagnetic Observatories EYR, SBA & API, processed at 1-minute and 1-second sampling, and submitted to INTERMAGNET in a standardized file format (IAGA-2002) every hour. The data are preliminary as they are submitted without being cleaned (spikes removed) and baseline (absolute values) corrected. The preliminary 1-minute data are more timely and potentially more complete than the definitive 1-minute data, whereas the 1-minute definitive data goes through a data quality reviewing process with data recorded in one year not being published until the following year. There are no 1-second definitive data being produced. The data can be downloaded via a free web access provided by INTERMAGNET at http://www.intermagnet.org/data-donnee/download-eng.php (Data Type: ‘provisional’). 1-minute data (Sample Rate: ‘minute’): EYR available since 1994, SBA since 1996, and API since 1999. 1-second data (Sample Rate: ‘second’): EYR data available since 2012, SBA since 2012, and API since 2012.