Signatures of Underground Nuclear Tests Observed in the Ionosphere
Abstract
Ionospheric disturbances can be observed following surface or underground nuclear weapons tests. Many other types of sources, however, can produce similar disturbances. Traveling waves are indeed frequently present in the ionosphere and exhibit strong variability. We propose to test the hypothesis that the time series of the Total Electron Content (TEC) of the ionosphere contains unique signatures, strongly correlated with an underground nuclear explosion as the source. Our goal is to determine the sensitivity of these signatures to source characteristics and the discrimination of weapons tests from other disturbance sources. The availability of large, dense networks of GNSS receivers enables the detection of these disturbances and mapping of their propagation over large geographical areas. Our approach will involve both statistical signal analysis of GNSS data collected during the 2006, 2009, 2013 and 2016 North Korean weapons tests and the application of efficient full-wave models, validated by time-dependent atmospheric acoustics models, for wave propagation through the atmosphere and ionosphere starting from an input source on the ground. Observational data will be used to validate and improve the model and predictions from the model will further our understanding of identifiable features, detectable in the waveforms, that can provide insight into physical sources. This proposed research has four primary objectives, supporting the broad purposes stated above. 1.) Apply a Spectral Full-Wave Model (SFWM) and further-develop its capabilities with a complementary ray-tracing extension, including validation comparisons with observations and results from a Time-Dependent Nonlinear Model (TDNM). The SFWM suite of models will efficiently simulate TEC signatures resulting from other anticipated source configurations and under varied parameters. 2.) Improve wavelet-based filtering methods to maximize the signal to noise ratio (SNR) of extracted disturbance waveforms within individual geographic ``sub-areas , filter bandwidths, and time windows and develop pattern classification methods to discriminate disturbances caused by underground nuclear tests from those caused by other sources. 3.) Identify physical origins of dominant features in the observed TEC waveforms and determine their relationships to quantifiable source parameters (e.g. yield strength or burial depth) 4.) Determine fundamental physical limits on the detectability and discrimination of weak underground test sources, evaluate the sensitivity of TEC array measurements to geometry and environmental conditions (e.g., winds, electron distribution), and quantify the spatial and temporal coherence of TEC disturbances generated following these sources.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 13, 2016
- Source ID
- HDTRA11610046
Entities
People
- James R. Garrison
Organizations
- Defense Threat Reduction Agency
- University of Virginia