The ionospheric response over the UK to major bombing raids during World War II
<p>The Earth's ionosphere is subject to disturbance from above (via solar variability and space-weather effects) and from below (such as tectonic activity, thunderstorms and sudden stratospheric warmings). Identifying the relative contribution of these effects remains challenging, desp...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-09-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/36/1243/2018/angeo-36-1243-2018.pdf |
| _version_ | 1819160291933421568 |
|---|---|
| author | C. J. Scott P. Major |
| author_facet | C. J. Scott P. Major |
| author_sort | C. J. Scott |
| collection | DOAJ |
| description | <p>The Earth's ionosphere is subject to disturbance from above (via solar
variability and space-weather effects) and from below (such as tectonic
activity, thunderstorms and sudden stratospheric warmings). Identifying the
relative contribution of these effects remains challenging, despite recent
advances in spacecraft monitoring near-Earth space. Man-made explosions
provide a quantifiable proxy for natural terrestrial sources, enabling their
impact on ionospheric variability to be studied. In this paper, the
contribution of ground-based disturbances to ionospheric variability is
investigated by considering the response of the ionospheric F2 layer over
Slough, UK, to 152 major bombing raids over Europe during World War II, using
a superposed epoch analysis. The median response of the F2 layer is a
significant decrease in peak electron concentration ( ∼ 0.3 MHz decrease
in <i>fo</i>F2). This response is consistent with wave energy heating the
thermosphere, enhancing the (temperature-dependent) loss rate of O<sup>+</sup>
ions. The analysis was repeated for a range of thresholds in both time of
bombing before the (noon) ionospheric measurement and tonnage of bombs
dropped per raid. It was found that significant ( ∼ 2–3<i>σ</i>)
deviations from the mean occurred for events occurring between approximately
3 and 7 h ahead of the noon ionospheric measurements and for raids using a
minimum of between 100 and 800 t of high explosives. The most
significant ionospheric response (2.99<i>σ</i>) occurred for 20 raids up to
5 h before the ionospheric measurement, each with a minimum of 300 t of
explosives. To ensure that the observed ionospheric response cannot be
attributable to space-weather sources, the analysis was restricted to those
events for which the geomagnetic Ap index was less than 48 (Kp < 5). Digitisation of the early ionospheric data would enable the
investigation into the response of additional ionospheric parameters
(sporadic E, E and F1 layer heights and peak concentrations). One metric ton
of TNT has an explosive energy of 4.184×10<sup>9</sup> J, which is of the
same order of energy as a cloud to ground lightning stroke. Since the
occurrence of lightning has distinctive diurnal and seasonal cycles, it is
feasible that a similar mechanism could contribute to the observed seasonal
anomaly in ionospheric F-region electron concentrations. Further
investigation, using less extreme examples, is required to determine the
minimum explosive energy required to generate a detectable ionospheric
response.</p> |
| first_indexed | 2024-12-22T16:54:07Z |
| format | Article |
| id | doaj.art-403e852604de428c8fcc351fedb2daa8 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-22T16:54:07Z |
| publishDate | 2018-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-403e852604de428c8fcc351fedb2daa82022-12-21T18:19:30ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762018-09-01361243125410.5194/angeo-36-1243-2018The ionospheric response over the UK to major bombing raids during World War IIC. J. Scott0P. Major1Department of Meteorology, University of Reading, Berkshire, UKDepartment of History, University of Reading, Berkshire, UK<p>The Earth's ionosphere is subject to disturbance from above (via solar variability and space-weather effects) and from below (such as tectonic activity, thunderstorms and sudden stratospheric warmings). Identifying the relative contribution of these effects remains challenging, despite recent advances in spacecraft monitoring near-Earth space. Man-made explosions provide a quantifiable proxy for natural terrestrial sources, enabling their impact on ionospheric variability to be studied. In this paper, the contribution of ground-based disturbances to ionospheric variability is investigated by considering the response of the ionospheric F2 layer over Slough, UK, to 152 major bombing raids over Europe during World War II, using a superposed epoch analysis. The median response of the F2 layer is a significant decrease in peak electron concentration ( ∼ 0.3 MHz decrease in <i>fo</i>F2). This response is consistent with wave energy heating the thermosphere, enhancing the (temperature-dependent) loss rate of O<sup>+</sup> ions. The analysis was repeated for a range of thresholds in both time of bombing before the (noon) ionospheric measurement and tonnage of bombs dropped per raid. It was found that significant ( ∼ 2–3<i>σ</i>) deviations from the mean occurred for events occurring between approximately 3 and 7 h ahead of the noon ionospheric measurements and for raids using a minimum of between 100 and 800 t of high explosives. The most significant ionospheric response (2.99<i>σ</i>) occurred for 20 raids up to 5 h before the ionospheric measurement, each with a minimum of 300 t of explosives. To ensure that the observed ionospheric response cannot be attributable to space-weather sources, the analysis was restricted to those events for which the geomagnetic Ap index was less than 48 (Kp < 5). Digitisation of the early ionospheric data would enable the investigation into the response of additional ionospheric parameters (sporadic E, E and F1 layer heights and peak concentrations). One metric ton of TNT has an explosive energy of 4.184×10<sup>9</sup> J, which is of the same order of energy as a cloud to ground lightning stroke. Since the occurrence of lightning has distinctive diurnal and seasonal cycles, it is feasible that a similar mechanism could contribute to the observed seasonal anomaly in ionospheric F-region electron concentrations. Further investigation, using less extreme examples, is required to determine the minimum explosive energy required to generate a detectable ionospheric response.</p>https://www.ann-geophys.net/36/1243/2018/angeo-36-1243-2018.pdf |
| spellingShingle | C. J. Scott P. Major The ionospheric response over the UK to major bombing raids during World War II Annales Geophysicae |
| title | The ionospheric response over the UK to major bombing raids during World War II |
| title_full | The ionospheric response over the UK to major bombing raids during World War II |
| title_fullStr | The ionospheric response over the UK to major bombing raids during World War II |
| title_full_unstemmed | The ionospheric response over the UK to major bombing raids during World War II |
| title_short | The ionospheric response over the UK to major bombing raids during World War II |
| title_sort | ionospheric response over the uk to major bombing raids during world war ii |
| url | https://www.ann-geophys.net/36/1243/2018/angeo-36-1243-2018.pdf |
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