Invalid Polar Cap (PC) indices: Erroneous scaling parameters.
In the publication Troshichev et al. (2006) on the Polar Cap (PC)
indices, PCN and PCS, an error was made by using components of the
Interplanetary Magnetic Field (IMF) in their Geocentric Solar Ecliptic
(GSE) representation instead of the prescribed Geocentric Solar
Magnetospheric (GSM) representation for calculations of index scaling
parameters. The mistake has caused a trail of incorrect relations and
wrong conclusions extending since 2006 up to now (2020) which should be
discontinued, for instance, by issuing a corrigendum note from the
authors. The present contribution explains the error and discusses in an
extended example its consequences for one of the publications that has
referred to the invalid scaling parameter set. Further investigations
reported here of the PC index versions recommended by the International
Association for Geomagnetism and Aeronomy (IAGA) indicate occurrences of
similar problems in the present derivation of index scaling parameters.