Environmental Engineering Reference
In-Depth Information
Lagrangian trajectories from point sources across the region calculated with the
MBLM model outputs reveal the complexity of low-level circulations over the of
the La Plata River region.
Figure 3
presents 24-h lagrangian trajectories that simulate the smoke plumes
from two continuous point sources in the region. The example aims at showing the
dependence of trajectories on horizontal model resolution. The left panels are
obtained by running the model at 15 km resolution, hereinafter referred to as low-
resolution or LR. The right panels correspond to a similar experiment at 5 km
resolution, referred to as high-resolution or HR. In each case, two experiments are
conducted with regional scale winds from different sectors (but same wind speed)
that remain constant throughout the integration. The upper panels correspond to
northeasterly wind and the lower panels correspond to southeasterly wind,
indicated by the thick arrow on the upper right corner of each panel. The LR case
shows clearly different lagrangian trajectories that develop downwind the regional
scale flow, i.e. northwestward and southwestward from the sources, respectively.
Instead, the HR case displays lagrangian trajectories that look alike closer to the
sources and differ only at longer distances. Also, the HR trajectories are clearly
longer than the LR trajectories. The HR experiments reveal the importance of the
local thermal forcing on the low level circulation that despite the change in the
regional scale wind direction, forces smoke plume trajectories strongly influenced
by the local conditions.
References
Berri G.J. and M.N. Nuñez (1993) Transformed shoreline-following horizontal coordinates in a
mesoescale model: A sea-land breeze case study, J. Appl. Meteorol., 5, 918-928 pp.
Berri G.J. (2007) Using a mesoscale boundary layer model forced with local observations to
define the low-level wind field climatology over the La Plata River region, II Encontro
Meteorologia Sul do Brasil, Florianopolis, Brasil, June 2007.
Sraibman L. and G.J. Berri (2009) Low level wind forecast over La Plata River region with a
mesoscale boundary layer model forced by regional operational forecasts, Boundary Layer
Meteorology, 130, 3, 407-422, DOI 10.1007/s10546-009-9350-1
