|
A monitoring campaign of atmospheric pollutants was conducted in February 1993 by several of Italy's CNR institute in heavily polluted greater Milan. This metropolitan area, the largest one in northern Italy, is situated in the northernmost part of the Po Valley and, because of its topography and orography is frequently marked by low ventilation and inversion phenomena, a fast that promotes the accumulation and vertical layering over the city of pollutants. The need for more detailed information on air circulation and changes occurring in the lower atmospheric layers, as well as to understand why air-mass exchange does not take place, thereby impeding the dispersion of pollutants, was the project's goal- orientation. Measurement of NO2, SO2, O3, HNO2 were carried out over a 1.7 Km path in the city center by means of a DOAS system called GASCOD developed by remote sensing group of FISBAT-CNR at Bologna. The light source has been equipped with a remote-controlled occulting devices in order to separate the sky light scattered into the field of bye of the receiving system, which can interfere with the lamp spectra during daytime. The light from the source is collected by a Cassegrain telescope and focused on the spectrograph's entrance slit receiving system; the detector is a linear image sensor featuring an array of 512 MOS photodiodes. Data recorded in the same and boundary areas by a conventional analyzer from city's air-pollution monitoring network are reported for comparison. The statistical correlation of concentration values to the main weather and atmospheric stability parameters are stressed.
|
