Comprehensive Nuclear-Test-Ban Treaty Organization

About: Comprehensive Nuclear-Test-Ban Treaty Organization is a based out in . It is known for research contribution in the topics: Infrasound & Nuclear explosion. The organization has 100 authors who have published 98 publications receiving 3395 citations. The organization is also known as: CTBTO.

Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2

Abstract: The Lagrangian particle dispersion model FLEXPART was originally (about 8 years ago) designed for calculating the long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis Its application fields were extended from air pollution studies to other topics where atmospheric transport plays a role (eg, exchange between the stratosphere and troposphere, or the global water cycle) It has evolved into a true community model that is now being used by at least 25 groups from 14 different countries and is seeing both operational and research applications A user manual has been kept actual over the years and was distributed over an internet page along with the model's source code In this note we provide a citeable technical description of FLEXPART's latest version (62)

Ozone production from Canadian wildfires during June and July of 1995

Abstract: [1] During the summer of 1995, especially between June and mid July, extensive wildfires occurred throughout Canada, primarily north of 55°N latitude. A previous report used aircraft and surface observations and tracer simulations to show these fires strongly influenced CO concentrations as far south as 35°N in the central and eastern United States [Wotawa and Trainer, 2000]. This study extends those results by incorporating wildfire emissions estimates for CO, NOx, and nonmethane hydrocarbons into a three-dimensional photochemical transport model specifically designed to simulate ozone photochemistry in the continental United States. The results of the model are compared to observations from four measurement platforms deployed during the time period of interest: National Oceanic and Atmospheric Administration WP-3 aircraft observations collected during the 1995 Southern Oxidants Study (SOS-95) field campaign; 12 eastern U.S. surface stations that measured ozone, CO, and NOy; rural ozone measurements from the Aerometric Information Retrieval System network collected by the U.S. Environmental Protection Agency; and daily ozonesondes obtained near Nashville, Tennessee, during SOS-95. Model performance, as determined by correlation and bias with observations from these four platforms, is significantly improved for both O3 and CO when the Canadian fires are considered. Both observations and model results show enhanced O3 from air transported from the Northwest Territory. The model results imply that during the period of strongest fire influence 10 to 30 ppbv enhancement of O3 throughout a large region of the central and eastern United States was due to these fires. Modeled O3 increases are sensitive to the NOx/CO emission ratio assumed for the fires, which is highly uncertain and variable. A molar NOx/CO ratio of 0.007 yields model comparisons that are most consistent for O3 and ΔO3/ΔCO observations within aged fire plumes during SOS-95, and is also consistent with previously observed NOx/CO ratios from boreal fires. For this NOx/CO emission ratio, and considering the entire eastern United States, most of the O3 increase is associated with the NOx emitted directly by the fires and the photochemical O3 formation that occurs before the plumes actually reach the United States. However, the in situ oxidation of CO from the Canadian fires with NOx emitted locally leads to significantly higher O3 increases for high-NOx-emitting regions that are limited by hydrocarbon availability. Thus O3 in urban areas, or any other region modified by nearby NOx sources, is more sensitive to long-range fires compared to less populated or polluted regions.

Discrimination of Nuclear Explosions against Civilian Sources Based on Atmospheric Xenon Isotopic Activity Ratios

Abstract: A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System that will verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) once the treaty has entered into force. This paper studies isotopic activity ratios to support the interpretation of observed atmospheric concentrations of 135Xe, 133mXe, 133Xe and 131mXe. The goal is to distinguish nuclear explosion sources from civilian releases. Simulations of nuclear explosions and reactors, empirical data for both test and reactor releases as well as observations by measurement stations of the International Noble Gas Experiment (INGE) are used to provide a proof of concept for the isotopic ratio based method for source discrimination.