A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values
Open Access
- 16 April 2018
- journal article
- research article
- Published by Copernicus GmbH in Annales Geophysicae
- Vol. 36 (2), 621-631
- https://doi.org/10.5194/angeo-36-621-2018
Abstract
The Polar Cap (PC) indices were approved by the International Association for Geomagnetism and Aeronomy (IAGA) in 2013 and made available at the web portal http://pcindex.org holding prompt (real-time) as well as archival index values. The present note provides the first reported examination of the validity of the IAGA-endorsed method to generate real-time PC index values. It is demonstrated that features of the derivation procedure defined by Janzhura and Troshichev (2011) may cause considerable excursions in the real-time PC index values compared to the final index values. In examples based on occasional downloads of index values, the differences between real-time and final values of PC indices were found to exceed 3 mV m−1, which is a magnitude level that may indicate (or hide) strong magnetic storm activity.Keywords
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