@book{3a3c929b5851429aad9fe71b307bb32b,
title = "Concentration fluctuations in gas releases by industrial accidents",
abstract = "The COFIN project studied existing remote-sensing Lidar data on concentration fluctuations in atmospheric dispersion from continuous sources at ground level. Fluctuations are described by stochastic models developed by a combination of statisticalanalyses and surface-layer scaling. The statistical moments and probability density distribution of the fluctuations are most accurately determined in a frame of reference following the instantaneous plume centreline. The spatial distribution of thesemoments is universal with a gaussian core and exponential tails. The instantaneous plume width is fluctuating with a log-normal distribution. The position of the instantaneous plume centreline is modelled by a normal distribution and a Langevin equation,by which the meander effect on the time-averaged plume width is predicted. Fixed-frame statistics are modelled by convolution of moving-frame statistics and the probability distribution for the plume centreline. The distance-neighbour function generalizedfor higher-order statistics has a universal exponential shape. Simulation tools for concentration fluctuations have been developed for either multiple correlated time series or multi-dimensional fields. These tools are based on Karhunen- Lo`eve expansionand Fourier transformations using iterative or correlation-distortion techniques. The input to the simulation is the probability distribution of the individual processes, assumed stationary, and the cross-correlations of all signal combinations. The usein practical risk assessment is illustrated by implementation of a typical heavy-gas dispersion model, enhanced for prediction and simulation of concentration fluctuations.",
keywords = "1-E vind, Ris{\o}-R-1329, Ris{\o}-R-1329(EN)",
author = "M. Nielsen and P.C. Chatwin and {Ejsing J{\o}rgensen}, Hans and N. Mole and R.J. Munro and S{\o}ren Ott",
year = "2002",
language = "English",
isbn = "87-550-3026-2",
series = "Denmark. Forskningscenter Risoe. Risoe-R",
number = "1329(EN)",
}