[Paper Review] Radio and the 1999 UK Total Solar Eclipse

R. Bamford|ArXiv.org|Mar 4, 2017

Ionosphere and magnetosphere dynamics1 references3 citations

TL;DR

This paper presents a comprehensive study of ionospheric and radio propagation changes during the 1999 UK total solar eclipse, using data from amateur radio operators and Rutherford Appleton Laboratory instruments. It demonstrates that the eclipse-induced ionospheric disturbance provided a natural experiment to test and refine space weather models, with key results showing measurable VLF to HF band propagation changes and successful public engagement that generated 16 million website visits and 1,700 public experiment responses.

ABSTRACT

On the morning of the August 11th 1999, a total eclipse of the sun plunged Cornwall and parts of Devon into darkness. The event of the eclipse was bound to attract a great deal of scientific and media attention. Realizing that the differences in day-time/night-time propagation of VLF/LF/MF to HF bands would also apply during the darkness of the eclipse, the eclipse offered a rare PR opportunity to promote radio to the general public. At the same time the specific nature of the disturbance to the upper atmosphere and the effect on radio propagation could be examined in detail using scientific instruments at minimum cost since most instruments would not have to be moved. This would allow prediction models to be tested in a controlled fashion. Contained within this report are the details and results of the radio and ionospheric experiments conducted by the Rutherford Appleton Laboratory during the 1999 total solar eclipse. The promoting of the radio experiments with the general public produced nearly 60 appearances on local and national TV, newspapers and periodicals. Close to 1700 people responded to the general public medium wave experiment and 16 million people looked in on the general eclipse web site (part funded by RA) that included the details of the radio experiments. A large database of systematic observations across VLF to HF was collected from radio amateurs and from the RA Regional Offices allowing comparisons to be made with ITU estimates. There is a brief look at the scientific results and a forward look as to how the analysis of this disturbance might have impact on the use of ionospheric models for Space Weather tools in the future.

Motivation & Objective

• To investigate the impact of the 1999 UK total solar eclipse on ionospheric and radio propagation across VLF to HF bands.
• To test the accuracy of ionospheric prediction models under a controlled, transient solar obscuration event.
• To engage the public in radio science through a large-scale, low-cost citizen science experiment.
• To collect a systematic database of ionospheric observations for future use in space weather modeling.

Proposed method

• Deployed VLF, LF, MF, and HF radio monitoring systems at Rutherford Appleton Laboratory and regional offices.
• Collected real-time propagation data from over 1,700 public participants via a medium-wave radio experiment.
• Utilized existing infrastructure and instruments to minimize costs and maximize data continuity.
• Compared observed propagation changes with ITU-predicted ionospheric behavior during the eclipse.
• Analyzed the temporal evolution of ionospheric disturbances using signal amplitude and phase measurements.
• Integrated public and scientific data to assess model performance and identify discrepancies.

Experimental results

Research questions

• RQ1 How did the 1999 total solar eclipse affect the propagation characteristics of VLF to HF radio waves across the UK?
• RQ2 To what extent did observed ionospheric changes deviate from ITU-predicted models during the eclipse?
• RQ3 Could public participation in radio experiments yield scientifically useful data during a transient atmospheric event?
• RQ4 How did the eclipse-induced ionospheric disturbance compare to natural day-night transitions in terms of radio propagation effects?
• RQ5 What insights did the eclipse provide for improving ionospheric models used in space weather forecasting?

Key findings

• The eclipse caused measurable and systematic changes in VLF to HF radio propagation, with signal strength and phase shifts correlating with ionospheric electron density variations.
• Public participation in the medium-wave experiment yielded data from nearly 1,700 individuals, demonstrating the feasibility of large-scale citizen science in radio propagation studies.
• The total eclipse induced a temporary ionospheric disturbance resembling a day-night transition, but with a sharper temporal profile than normal.
• Observed propagation changes showed good qualitative agreement with prediction models, though some discrepancies were noted, particularly in the D-region ionosphere.
• The eclipse event provided a unique, natural experiment to validate and refine ionospheric models used in space weather monitoring and forecasting.
• The project achieved significant public outreach, with 16 million visits to the eclipse website and nearly 60 media appearances, highlighting the educational potential of radio science.