Review of "Atmospheric Electricity Observations at Eskdalemuir Geophysical Observatory" by R.G. Harrison and J.C. Riddick

The manuscript addresses historical matters relevant to the HGSS journal. It explores the historical development of atmospheric electricity measurements at Eskdalemuir Observatory, aligning with the focus of HGSS. The abstract provides a concise and comprehensive summary of the key aspects of the research, including the scope, methods, and significance of the historical measurements of atmospheric electricity at Eskdalemuir. The overall presentation of the manuscript is well-structured and clear. It logically progresses from an introduction of the observatory and its historical context to detailed descriptions of the instruments and methods used, followed by an analysis of the data and its implications. The language used in the manuscript is fluent and precise. In conclusion, the manuscript is a valuable contribution to the field of atmospheric electricity and its historical study. This reviewer recommends it for publication.

Typing error:

- Data availability. Please verify the link for Lerwick's data. The doi should be: https://doi.org/10.17864/1947.000505

This is a remarkable paper. It is remarkable because it presents new measurements of a crucial parameter in atmospheric electricity, namely the potential gradient (PG) at the surface of the Earth. It is even more remarkable that the data set presented is seventy years long, from 1911 to 1981.  Hourly values of the PG are presented from Eskdalemuir, in Scotland, a geophysical observatory operated by the UK Met Office from 1910 to 1968, when responsibility was transferred to the Natural Environmental Research Council.

Thanks to the dedication and diligence of the authors, as well as of the original observers, researchers in atmospheric electricity around the world now have access to an entirely new – and digital - data set. Other relevant observations in atmospheric electricity at Eskdalemuir are also discussed here; these are the concentrations and mobilities of both positive and negative ions at ground level which determine the electrical conductivity of the air. The modus operandi of different instruments for observing the PG are given. Relationships between the hourly PG values and the local weather are investigated. Fig. 7a shows the monthly mean of the PG on days of fair weather for seventy years; a clear annual variation is evident. From around 1957 to 1965 this graph shows a generally much reduced PG, which is ascribed to the decrease of the electrical conductivity of the air at the time when several tests of nuclear weapons were carried out in the atmosphere. Fig. 9b links monthly mean PG values from 1911 to 1950 to the El Nino Southern Oscillation signal in the atmosphere via the atmospheric global electric circuit.

In my opinion, this is an excellent paper which deserves to be published without any changes.