|
Air pollution episodes in urban areas often occur during low wind speeds and low mixing layer height (MLH) and can
not only be ascribed to increased local anthropogenic emissions. The continuous knowledge of MLH is supporting the
understanding of processes directing air quality. If the MLH is located near to the ground, which occurs mainly during
winter and night-time, air pollution can be high due to a strongly limited air mass dilution.
The Vaisala ceilometer CL31, which is an eye-safe commercial mini-lidar system, is used for long-term continuous
remote sensing of MLH. The ceilometer measurements provide information about the range-dependent aerosol
concentration; gradient minima within this profile mark the borders of mixed layers. Special software for this ceilometer
developed with MATLAB provides routine retrievals of lower atmosphere layering from vertical profiles of laser
backscatter data. To study the gaseous pollutants and those compounds important for secondary aerosol formation like
NO and NO2 as well as O3
The data retrieval software is extended to improve remote sensing of MLH. The original 10-minute-interval values are
used to calculate continuous 1-hour-mean values. Gaps and strong variations of the original data are considered. The
results of investigations of the meteorological influences and the role of emissions within the context of the air quality in
Augsburg are discussed.
a DOAS is operated since March 2012 in Augsburg. Information about different road traffic
emissions is provided by this one instrument i.e. by path-integrated air pollution information in different directions. The
DOAS contains an analyser and an emitter/receiver unit pointing to three retroreflectors. The retroreflectors were
installed at lamp masts so that the paths were about 10 m above street level and perpendicular across the streets. The
emitter/receiver unit was in a distance of about 20 m to an in situ air pollution measurement station at the ground.
Ground-based (weather station) and radiosonde (German National Meteorological Service (DWD), Oberschleißheim)
measured meteorological data are used.
|
