Ionospheric Detection of Explosive Events

Abstract

The ionospheric response to explosions which occur at or below the Earth's surface has been noted since the first detonations of nuclear devices during the early period of aboveground testing. Acoustic gravity waves and traveling ionospheric disturbances were detected in association with test explosions carried out by the Union of Soviet Socialist Republics in Novaya Zemlya in 1961. While research in this area has continued, the standards accepted by the Comprehensive Nuclear Test Ban Treaty for detection and confirmation of nuclear explosions have been based on (1) seismic, (2) hydroacoustic, (3) infrasound, and (4) radionuclide monitoring from ground detectors. We suggest that ionospheric sensing offers a complementary methodology that may allow for robust confirmation of explosive events. One method of ionospheric monitoring of explosive events is analysis of total electron content (TEC), available by processing data from Global Navigation Satellite System (GNSS) receivers distributed globally on land masses. Traveling ionospheric disturbances observed by their signature in TEC have been used to detect and confirm mine collapses, mine blasts, earthquakes, volcanic eruptions, and meteorite strikes as well as underground nuclear tests. While an integrated measurement like TEC is not as sensitive to small-amplitude density perturbations as other methods, the existence of large networks of continuously operating GNSS stations makes this an intriguing new monitoring asset. We report on the current capabilities for detection of explosions via the ionosphere, the outstanding challenges, and prospects for future developments that have potential to augment the current standards for detection and confirmation of nuclear detonations. By leveraging the worldwide network of GNSS receivers, robust confirmation of impulsive events is possible. This methodology complements existing technologies approved by the Comprehensive Test Ban Treaty. The article outlines background theory, new approaches to monitoring of explosions, and challenges that remain to be addressed.

Ionospheric Detection of Natural Hazards

“…Huang et al () have recently provided an extended review on ionospheric detection of explosive events. The current review article is exclusively targeted at ionospheric detection of such natural hazards as earthquakes, tsunamis, and volcanic eruptions.…”

“…In response to this need, it has recently been suggested that the ionosphere-based technique could, in future, present a novel approach for NH-detection in near-real time (e.g., Savastano et al, 2017). Huang et al (2019) have recently provided an extended review on ionospheric detection of explosive events. The current review article is exclusively targeted at ionospheric detection of such natural hazards as earthquakes, tsunamis, and volcanic eruptions.…”

Upper Atmospheric Responses to Surface Disturbances: An Observational Perspective

“…The ionospheric disturbances due to explosions have been identified with ionosondes (e.g., Beynon & Jones, ; Dieminger & Kohl , ; Gardiner , ; Hines, ), Doppler sounders (Jacobson et al, ; Blanc & Jacobson, ; Blanc & Rickel, ; Krasnov & Drobzheva, ), and GPS‐bases TEC measurements (Calais et al, ; Fitzgerald & Carlos , ; Park et al, , ; Yang et al, ; Zhang & Tang, ). Both atmospheric acoustic and gravity wave signatures have been observed (Huang et al, ). For explosions above the ground, the generation of atmospheric acoustic‐gravity waves can be explained by the same mechanisms as for volcanic eruptions.…”

“…Moderate and small surface disturbance events may well generate weak upper atmospheric signatures that could be comparable to the noise level of some of the existing observational techniques. This could motivate the development and application of more precise upper atmospheric monitoring techniques and systems, for instance, radio frequency interferometry measurements (Huang et al, ). How the upper atmospheric response varies with the state of the background atmosphere is a fundamental question to address. For instance, the background neutral wind has a significant influence on the propagation of atmospheric acoustic‐gravity waves.…”

“…These observations have provided insights on the coupling mechanisms between surface disturbances and the upper atmosphere. Consequently, researchers have gained a good understanding of the acoustic‐gravity waves generated from different types of impulsive surface disturbances and the corresponding upper atmospheric responses (e.g., Artru, Ducic, et al, ; Astafyeva et al, ; Chum et al, ; Heki, ; Hickey, ; Huang et al, ; Jin et al, ; Lognonné et al, ; Liu et al, ; Makela et al, ; Nakashima et al, ; Occhipinti et al, ; Rolland et al, )…”