This data publication includes the half-hourly Hp30 and ap30 indices as well as the hourly Hp60 and ap60 indices. All are unitless and collectively denoted as Hpo or Hpo index family. The dataset is based on near real-time geomagnetic observatory data provided by 13 contributing observatories. It is derived and distributed by GFZ German Research Centre for Geosciences. When using the Hpo index, please cite this data publication as well as the accompanying publication Matzka et al. (in prep), which serves as documentation of the Hpo index family.

The dataset is organised in yearly files, which, for the current year, are updated on a monthly basis. Typically, during the second week of a month, the data for the previous month is appended to the current year's file. The files are in ASCII files and start with header lines marked with # (hash).

The Hpo index was developed within the H2020 project SWAMI and is produced by Geomagnetic Observatory Niemegk, GFZ German Research Centre for Geosciences. It derives from the same 13 geomagnetic observatories that also contribute to the Kp index (Matzka et al., 2021). They are listed as contributors to this data publication.

With the introduction of the DOI ‘https://doi.org/10.5880/Hpo.0001’, this DOI landing page and the associated FTP server linked to the DOI become the primary archive of Hpo (while the other established index distribution mechanisms at GFZ will be maintained in parallel). With the DOI, the dataset can grow with time, but a change of the data, once published, is not possible. If necessity arises in the future to correct already published values, then the corrected dataset will be published with a new DOI. Older DOIs and data sets will then still be available. For each DOI, an additional versioning mechanism will be available to document changes to the files such as header or format changes, which do not affect the integrity of the data. The DOI https://doi.org/10.5880/Hpo.0001 identifies the current version. A format description is provided in the data download folder.

The dataset is organised in yearly files, which, for the current year, are updated on a monthly basis. Typically, during the second week of a month, the data for the previous month is calculated and appended to the current year's file, both for the definitive and nowcast version. While the definitive Kp (and derived indices) are calculated from K values provided by the contributing observatories, the nowcast Kp (and derived indices) are calculated at GFZ from observatory data provided by the contributing observatories.

The data are distributed in ASCII files. All files start with 10 header lines, each starting with a number sign (#, hash) and containing DOI as well as license information. Note that leading zeroes are not shown, they are represented by blanks. Missing data would be represented by -1.

For more information, please refer to the associated data description and Matzka et al. (in prep).