Projects at the Radio Communications Research Unit (RCRU)

RUTHERFORD APPLETON LABORATORY

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.

Contents

Acknowledgements
List of figures

Introduction

1. Project objectives
2. The nature of an eclipse
3. Why the eclipse was able to affect radio propagation

Radio experiments during the solar eclipse

1. General public medium wave experiment
2. Results from the general public radio experiment

The VLF to HF Bands

1. Results from the radio amateurs
2. Propagation at 1440 kHz

Observations made by the ionosondes on the ionosphere

Analysis and modelling of the results

1. Reduction in the MUF and effect on propagation
2. Temporal variation of the eclipse effect and solar emission
3. Modelling the ionospheric response

Contacts with the media and general public

1. The eclipse website
2. Appearances of the radio experiments in the media

Summary

References

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