196
Air Pollution and Turbulence: Modeling and Applications
to calculate the ground-level concentration of emissions released from an elevated
continuous source point in an unstable/neutral ABL, considering radioactive material released during Angra dos Reis experiment (Biaggio et al., 1985).
Bearing in mind that in this work our aim is to show the feasibility of the proposed
models to simulate pollutant dispersion in atmosphere for more realistic problem, we
are now in a position to specialize the application of this methodology for a problem
with the wind speeds evaluated by the MesoNH research model (Lafore et al., 1998;
Cuxart et al., 2000) and the micrometeorological parameters by the LES model.
The MesoNH has different parameterizations and can be run in different modes,
from mesoscale to LES. The model uses an inelastic system of equations written
with a Gal-Chen and Sommerville vertical system of coordinates. The turbulence
closures available are the eddy diffusivity based on the TKE budget equation of
Cuxart et al. (2000) and the EDMF (eddy diffusivity/mass-fl ux) scheme developed
by Soares et al. (2004). The convection scheme is based on a bulk mass-fl ux convection parameterization for deep and shallow convection (Bechtold et al., 2001).
MesoNH has a statistical subgrid condensation scheme, based on the distributions of
the grid scale values of θ l and q t , and their variances, which are supplied by the general turbulence scheme (Cuijpers and Bechtold, 1995). The radiative scheme implemented in MesoNH is the one of the European Center for Medium range Weather
Forecasting (ECMWF) model.
This study is based on a simulation with four nested grids, the coarser two run in
the regional mode and the inner two grids in LES mode, with two-way interaction
between them. The outer grid is forced by re-analysis of the ECMWF model. The
main properties of the four grids are the following: Grid 1 (mesoscale, horizontal
resolution: 10 km, (nx, ny, nz) = 60 × 60 × 120 and Δt = 8 s); Grid 2 (mesoscale, horizontal resolution: 2 km, (nx, ny, nz) = 60 × 60 × 120 and Δt = 4 s); Grid 3 (LES, horizontal
resolution: 400 m, (nx, ny, nz) = 120 × 120 × 120 and Δt = 1 s); Grid 4 (LES, horizontal
resolution: 100 m, (nx, ny, nz) = 96 × 96 × 120 and Δt = 0.5 s).
The experiment consisted in the controlled releases of radioactive tritiated water
vapor from the meteorological tower, 100 m height, close to the power plant in
Itaorna Beach, from November 28 to December 4, 1984 (Biagio et al., 1985). The
nuclear power plant is located at a latitude −23.0079 and a longitude −44.4612. The
total time of emission was 90 min for each day, in all cases around midday LST.
The collection of water vapor over cooled aluminum plates in the numbered location took place in three subsequent periods (1, 2, and 3) of 20 min each, 30 min after
the beginning of the release, to allow the source and the plume transport to reach a
supposed stationary condition on the measurement area. All relevant details, as well
as the synoptic meteorological conditions during the dispersion campaign are also
described in Biagio et al. (1985). In this work, the simulations were accomplished
on the fi rst day (28 November). The roughness length utilized was z o = 1 m and the
emission rate Q = 20.5 MBq/s.
The micrometeorological dataset, obtained from LES model, used to obtain
the numerical results were the friction velocity u * = 0.4 m/s, convective velocity
w * = 1.6 m/s, and h = 1200 m is the ABL height. Table 7.6 presents the statistical
performances obtained in the simulations with wind fi eld and micrometeorological
parameters from MesoNH (LES) and semiempirical equations. Here also appears
© 2010 by Taylor and Francis Group, LLC
Air Pollution and Turbulence: Modeling and Applications
to calculate the ground-level concentration of emissions released from an elevated
continuous source point in an unstable/neutral ABL, considering radioactive material released during Angra dos Reis experiment (Biaggio et al., 1985).
Bearing in mind that in this work our aim is to show the feasibility of the proposed
models to simulate pollutant dispersion in atmosphere for more realistic problem, we
are now in a position to specialize the application of this methodology for a problem
with the wind speeds evaluated by the MesoNH research model (Lafore et al., 1998;
Cuxart et al., 2000) and the micrometeorological parameters by the LES model.
The MesoNH has different parameterizations and can be run in different modes,
from mesoscale to LES. The model uses an inelastic system of equations written
with a Gal-Chen and Sommerville vertical system of coordinates. The turbulence
closures available are the eddy diffusivity based on the TKE budget equation of
Cuxart et al. (2000) and the EDMF (eddy diffusivity/mass-fl ux) scheme developed
by Soares et al. (2004). The convection scheme is based on a bulk mass-fl ux convection parameterization for deep and shallow convection (Bechtold et al., 2001).
MesoNH has a statistical subgrid condensation scheme, based on the distributions of
the grid scale values of θ l and q t , and their variances, which are supplied by the general turbulence scheme (Cuijpers and Bechtold, 1995). The radiative scheme implemented in MesoNH is the one of the European Center for Medium range Weather
Forecasting (ECMWF) model.
This study is based on a simulation with four nested grids, the coarser two run in
the regional mode and the inner two grids in LES mode, with two-way interaction
between them. The outer grid is forced by re-analysis of the ECMWF model. The
main properties of the four grids are the following: Grid 1 (mesoscale, horizontal
resolution: 10 km, (nx, ny, nz) = 60 × 60 × 120 and Δt = 8 s); Grid 2 (mesoscale, horizontal resolution: 2 km, (nx, ny, nz) = 60 × 60 × 120 and Δt = 4 s); Grid 3 (LES, horizontal
resolution: 400 m, (nx, ny, nz) = 120 × 120 × 120 and Δt = 1 s); Grid 4 (LES, horizontal
resolution: 100 m, (nx, ny, nz) = 96 × 96 × 120 and Δt = 0.5 s).
The experiment consisted in the controlled releases of radioactive tritiated water
vapor from the meteorological tower, 100 m height, close to the power plant in
Itaorna Beach, from November 28 to December 4, 1984 (Biagio et al., 1985). The
nuclear power plant is located at a latitude −23.0079 and a longitude −44.4612. The
total time of emission was 90 min for each day, in all cases around midday LST.
The collection of water vapor over cooled aluminum plates in the numbered location took place in three subsequent periods (1, 2, and 3) of 20 min each, 30 min after
the beginning of the release, to allow the source and the plume transport to reach a
supposed stationary condition on the measurement area. All relevant details, as well
as the synoptic meteorological conditions during the dispersion campaign are also
described in Biagio et al. (1985). In this work, the simulations were accomplished
on the fi rst day (28 November). The roughness length utilized was z o = 1 m and the
emission rate Q = 20.5 MBq/s.
The micrometeorological dataset, obtained from LES model, used to obtain
the numerical results were the friction velocity u * = 0.4 m/s, convective velocity
w * = 1.6 m/s, and h = 1200 m is the ABL height. Table 7.6 presents the statistical
performances obtained in the simulations with wind fi eld and micrometeorological
parameters from MesoNH (LES) and semiempirical equations. Here also appears
© 2010 by Taylor and Francis Group, LLC