Pieter De Meutter

Predicting Small-Scale, Short-Lived Downbursts: Case Study with the NWP Limited-Area ALARO Model for the Pukkelpop Thunderstorm

AbstractThe authors consider a thunderstorm event in 2011 during a music festival in Belgium that produced a short-lived downburst of a diameter of less than 100 m. This is far too small to be resolved by the kilometric resolutions of today’s operational numerical weather prediction models. Operational forecast models will not run at hectometric resolutions in the foreseeable future. The storm caused five casualties and raised strong societal questions regarding the predictability of such a traumatic weather event.In this paper it is investigated whether the downdrafts of a parameterization scheme of deep convection can be used as proxies for the unresolved downbursts. To this end the operational model ALARO [a version of the Action de Recherche Petite Echelle Grande Echelle-Aire Limitee Adaptation Dynamique Developpement International (ARPEGE-ALADIN) operational limited area model with a revised and modular structure of the physical parameterizations] of the Royal Meteorological Institute of Belgium is u...

On the capability to model the background and its uncertainty of CTBT-relevant radioxenon isotopes in Europe by using ensemble dispersion modeling

Knowledge on the global radioxenon background is imperative for the Comprehensive Nuclear-Test-Ban Treaty verification. In this paper, the capability to simulate the radioxenon background from regional sources is assessed at two International Monitoring System stations in Europe. An ensemble dispersion modeling approach is used to quantify uncertainty by making use of a subset of the Ensemble Prediction System of the European Centre for Medium-Range Weather Forecasts. Although the uncertainty quantification shows promising results, the ensemble shows a lack of spread that could be attributed to emission uncertainty from nuclear power plants, which is not taken into account. More knowledge on the emissions of nuclear power plants can help improve our understanding of the radioxenon background.

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

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 International Monitoring System is being set up aiming to detect violations of the Comprehensive Nuclear-Test-Ban Treaty. Suspicious radioxenon detections were made by the International Monitoring System after the third announced nuclear test conducted by the Democratic People’s Republic of Korea (DPRK). In this paper, inverse atmospheric transport and dispersion modelling was applied to these detections, to determine the source location, the release term and its associated uncertainties. The DPRK nuclear test site was found to be a likely source location, though a second likely source region in East Asia was found by the inverse modelling, partly due to the radioxenon background from civilian sources. Therefore, techniques to indirectly assess the influence of the radioxenon background are suggested. In case of suspicious radioxenon detections after a man-made explosion, atmospheric transport and dispersion modelling is a powerful tool for assessing whether the explosion could have been nuclear or not.

Backtracking Radioxenon in Europe Using Ensemble Transport and Dispersion Modelling

The Comprehensive nuclear Test-Ban-Treaty bans nuclear explosions by everyone, everywhere. Radioxenon monitoring by the International Monitoring System is a key component of the verification of the Treaty. Atmospheric transport modelling can be used to determine the sources of radioxenon plumes. The Flexpart model is used to backtrack radioxenon observations in Europe to determine their source. An ensemble is used to quantify uncertainty.