Z. Boybeyi et al., Evaluation of the operational multiscale environment model with grid adaptivity against the European tracer experiment, J APPL MET, 40(9), 2001, pp. 1541-1558
The Operational Multiscale Environment Model with Grid Adaptivity (OMEGA) i
s a multiscale nonhydrostatic atmospheric simulation system based on an ada
ptive unstructured grid. The basic philosophy behind the OMEGA development
has been the creation of an operational tool for real-time aerosol and gas
hazard prediction. The model development has been guided by two basic desig
n considerations in order to meet the operational requirements: 1) the appl
ication of an unstructured dynamically adaptive mesh numerical technique to
atmospheric simulation, and 2) the use of embedded atmospheric dispersion
algorithms. An important step in proving the utility and accuracy of OMEGA
is the full-scale testing of the model using simulations of real-world atmo
spheric events and qualitative as well as quantitative comparisons of the m
odel results with observations. The main objective of this paper is to prov
ide a comprehensive evaluation of OMEGA against a major dispersion experime
nt in operational mode. Therefore, OMEGA was run to create a 72-h forecast
for the first release period (23-26 October 1994) of the European Tracer Ex
periment (ETEX). The predicted meteorological and dispersion fields were th
en evaluated against both the atmospheric observations and the ETEX dispers
ion measurements up to 60 h after the start of the release. In general, the
evaluation showed that the OMEGA dispersion results were in good agreement
in the position, shape, and extent of the tracer cloud. However, the model
prediction indicated that there was a limited spreading of the predictions
around the measurements with a small tendency to underestimate the concent
ration values.