Assessment of the announced North Korean nuclear test using long-range atmospheric transport and dispersion modelling

Abstract

On 6 January 2016, the Democratic People’s Republic of Korea announced to have conducted its fourth nuclear test. Analysis of the corresponding seismic waves from the Punggye-ri nuclear test site showed indeed that an underground man-made explosion took place, although the nuclear origin of the explosion needs confirmation. Seven weeks after the announced nuclear test, radioactive xenon was observed in Japan by a noble gas measurement station of the International Monitoring System. In this paper, atmospheric transport modelling is used to show that the measured radioactive xenon is compatible with a delayed release from the Punggye-ri nuclear test site. An uncertainty quantification on the modelling results is given by using the ensemble method. The latter is important for policy makers and helps advance data fusion, where different nuclear Test-Ban-Treaty monitoring techniques are combined.

Source localisation and its uncertainty quantification after the third DPRK nuclear test

“…The threshold was set at the 0.01 quantile of all grid box cost function values (the total number of grid boxes was 13,680). A possible source location probability map was then constructed by taking the percentage of members having a cost function below the threshold for each grid box, as was done in a previous study 19 . This is justified by the fact that in the Ensemble Data Assimilation system of ECMWF, each member can be considered equally likely, hence each member should have equal weighting.…”

“…After the announced nuclear test in January 2016, elevated 133 Xe concentrations were measured by the International Monitoring System, compatible with a delayed release from the Punggye-ri nuclear test site 19 . However, due to the lack of detections of other radioxenon isotopes, it could not be excluded that the observed 133 Xe originated from civilian sources.…”

“…In this paper, the existing methodology 19 was extended to improve the estimation of the source location and to address the problem of the radioxenon background. Inverse long-range atmospheric transport and dispersion modelling was used to assess the source location of the radioxenon detections previously described 14 .…”

Seasonal Variability of Xe‐133 Global Atmospheric Background: Characterization and Implications for the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty

“…The existence of an atmospheric background for Xe‐133 makes it more complex to apply numerical methods for source localization, as events of interest might not be clearly identified (what is a detection and what is a nondetection in a context of quasi‐daily Xe‐133 signal?). Therefore, characterization of the Xe‐133 atmospheric background is currently crucial for analysis of detections in the framework of the CTBT (e.g., De Meutter et al, ). On the other hand, for the three other xenon isotopes of interests, existence of (rare) detections and nondetections brings useful constraining information for localization purposes.…”