The Use of Invalid Polar Cap South (PCS) Indices in Publications

Abstract

Polar Cap (PC) indices, PCN North based on magnetic observations from Qaanaaq (THL) in Greenland and PCS South based on magnetic data from Vostok in Antarctica, are very useful indices for studies of solar wind‐magnetosphere interactions and for space weather monitoring and forecasts. PCN indices are issued from the Danish Space Research Institute (DTU Space) while PCS indices are issued from the Arctic and Antarctic Research Institute (AARI) in St Petersburg. Unfortunately, series of invalid PCS values have been provided from AARI and used in a number of publications issued since the PC index concept was endorsed by the International Association of Geomagnetism and Aeronomy (IAGA) in 2013. In spite of the disclosure of the failure in the PCS indices in 2018, publishing at the IAGA‐supported International Service of Geomagnetic Indices of the invalid indices has continued up to now (2022). The present contribution defines the invalidating features of the PCS indices in question, conveys examples, and discusses the applications in peer‐reviewed publications.

Comment on “The Use of Invalid Polar Cap South (PCS) Indices in Publications” by Stauning

“…After the IAGA-2013 decision the IAGA endorsed PC index was repeatedly criticized in papers (Stauning, 2013a(Stauning, , 2013b(Stauning, , 2015(Stauning, , 2018(Stauning, , 2020(Stauning, , 2021 as invalid index with reference to imagined inaccuracies in the TJS2006 method. In contrast to previous publications, the present paper (Stauning, 2022) claims that only PCS index is "invalid" index. To justify this transformation, it is alleged (Stauning, 2022) that the IAGA 2013 approval was related only to PCN, but not to PCS index.…”

“…In contrast to previous publications, the present paper (Stauning, 2022) claims that only PCS index is "invalid" index. To justify this transformation, it is alleged (Stauning, 2022) that the IAGA 2013 approval was related only to PCN, but not to PCS index. It should be reminded in this connection that the IAGA-2013 decision was based on results of many analyses fulfilled with use of the preliminary PCN and PCS indices derived by the "unified" TJS2006 method.…”

“…3. "It is admitted by Dr. Troshichev and colleagues at AARI that the pre-2021 PCS indices were faulty (which is the main point of Stauning, 2022) with the statement: "According to the IAGA rules, all indices obtained by data of current magnetic observations are considered as "preliminary" indices. They should be recalculated afterward making allowance for all possible faults of observational, technical and computer-assisted origin, to produce "definitive" indices, which will be valid for ever.…”

“…The difference between the daily values of PCN and PCS is the highest (>1 mV/m) in epochs of solar activity maximum and is minimal (<0.5 mV/m) in the quiet periods. Thus, exceeding of the PCsummer index values over the PCwinter values is conditioned by physics of the solar wind—magnetosphere coupling (see Troshichev & Janzhura, 2012; Troshichev et al., 2022), not by bad quality of the PCS or PCN indices, which are demonstrate the perfect agreement in equinox. “It is admitted by Dr. Troshichev and colleagues at AARI that the pre‐2021 PCS indices were faulty (which is the main point of Stauning, 2022) with the statement: “According to the IAGA rules, all indices obtained by data of current magnetic observations are considered as “preliminary” indices. They should be recalculated afterward making allowance for all possible faults of observational, technical and computer‐assisted origin, to produce “definitive” indices, which will be valid for ever.…”

Comment on “The PC Index Variations During 23/24 Solar Cycles: Relation to Solar Wind Parameters and Magnetic Disturbances” by Troschichev et al.

“…Further examples of the invalid PCS indices are provided in Stauning (2018bStauning ( , 2020. A comprehensive report on the invalid PCS index series and its application in publications issued from AARI is provided in Stauning (2022).…”