English Abstract A programme has been developed for measuring
concentrations of ammonia in high emission areas aiming at the validation of
the system emission/dispersion/deposition of the transport model TREND
(Asman and Van Jaarsveld, 1990). On two locations in the Netherlands
(Vredepeel, Ede) the concentration of ammonia will be monitored. To analyse
the spatial representativeness of the measurements for a 5 x 5 km2 grid cell
additional measurements will be carried out. A measuring strategy has been
developed based upon a phenomenological study of the behaviour of ammonia in
ambient air and measurement simulations by using existing data. The main
results of the phenomenological study show a positive temperature effect for
the Elspeet data (high temperature, high concentrations) and also a distinct
diurnal pattern with higher concentrations during the day (7 mug/m3) and
lower concentrations during the night (3 mug/m3). Monthly average
concentrations show small variations for the Elspeet data and higher
concentrations during early spring for the Vredepeel data. Peak
concentrations (>90- percentile value) show no clear correlation with
meteorological conditions. The simulations show a 20% inaccuracy in
determining the annual average concentration for each additional location in
the 5 x 5 km2 grid cell upon application of the developed measuring
strategy.
