The open-ended, high cadence, Kp-like geomagnetic Hp30 and Hp60 indices

The new planetary open-ended Hpo index family (consisting of the half-hourly Hp30 and hourly Hp60) has been developed within the Space Weather Atmosphere Models and Indices (SWAMI) project (see http://swami-h2020.eu/) of the H2020 European Union research activity. These new indices resemble the Kp index by having a similar derivation scheme and a nearly identical frequency distribution of index values for events with values < 9. However, they have provided a better temporal resolution than the 3-hourly Kp index. Additionally, the events with values > 9- are further subdivided using an open-ended scale (9o, 9+, 10-, 10o, 10+, 11-, ...) to better represent different levels of strong geomagnetic activity. In this study, the advantages and integrity of Hp30 and Hp60 indices are analysed and discussed. The comparison of these indices with the 3-hourly Kp index in terms of frequency distribution and correlation and with other geophysical parameters are also presented.Near real-time indices and archive indices back to 1995 are available from GFZ under the CC BY 4.0 license including linear versions of the Hp30 and Hp60 indices, the ap30 and ap60 indices (see https://www.gfz-potsdam.de/en/section/geomagnetism/data-products-services/hpo-index/). Near real-time plots of the Hp30, Hp60 and Kp indices for the current day and the previous six days are also provided.