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

Declaration (Stauning, 2022, https://doi.org/10.1029/2022JA030355) on “invalid polar cap south (PCS) index” is based on the following arguments: PCS index is calculated with use of incorrect “unified” PC derivation method; PCS index used in analyses is a preliminary index, which was not approved by IAGA and, therefore, it cannot be regarded as a correct index; PCN and PCS indices demonstrate, intermittently, large difference in value, which should be treated as evidence of the PCS index invalidity. The paper presents comments to these arguments. Conclusion is made that criticism of the PCS index, presented in Stauning (2022, https://doi.org/10.1029/2022JA030355), is based on groundless arguments. [ABSTRACT FROM AUTHOR]