The new 33 year atmospheric hindcast offers new scope for those wishing to carry out air quality studies with Lagrangian Trajectory modelling, to forecast the outcome of an atmospheric release, or to diagnose the source of any detected contaminant. The hindcast also provides a way of obtaining suitable meteorological data, to drive a Steady State Gaussian model in data sparse areas.
Lagrangian Trajectory Modelling
Most Lagrangian Trajectory models have the ability to be driven off gridded
global weather models such as ECMWF and GFS. These would have horizontal resolutions of at most 16km and 30km respectively and where the full gridded fields
(required to drive the air quality models) are only available at 3 hourly
intervals. This approach is fine for regional scales, but for scales of around
10km or less, or where there is very complex terrain, higher resolution input
data is required. A number of Air Quality models, such as HYSPLIT and
FLEXPART have been adapted to use the higher resolution of models such as WRF
for these reasons. MSL’s hindcast was constructed using WRF and is available
down to a resolution of 4km in some areas to drive these Air Quality models.
Steady State Gaussian Modelling
For those wishing to run steady state models, the metorological data at the
site of interest is of key importance. However, there are not always
observations available for the researcher to use. Interpolating surrounding
observations to the site, or even using coarse model data may not give the
desired level of confidence. Interpolating the high resolution hindcast data
to the site may be the best option in some areas.