P. Bacci

The urban heat island of Milan

SummaryHeat island contribution to the 148 year temperature series of Milan is evaluated by comparing Milan urban series with Milan airport series and with other European and North Hemispheric series. The heat island trend is then compared with the growth of the city radius and finally two relations between the city radius and the efffects of the heat island are determined.

The CISE PIXE system for aerosol characterization in several Italian sites

Abstract The CISE tandem Van de Graaff accelerator has been extensively devoted to environmental research for use in atomic and nuclear techniques such as particle induced X-ray emission (PIXE), Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) for some years now. The last two techniques were set up as tools complementary to the PIXE technique for the detection of light elements, in particular carbon and oxygen. A thorough characterization of Milan aerosols, sampled over a whole year, is discussed. Concentrations and size distributions of many elements were measured in order to investigate the elements of toxicological interest, to extend the analyses to trace elements and to identify correlations with SO 2 and NO x concentrations. In the same context, particulate samples collected over short periods in many Sicilian towns were analyzed. The analysis of atmospheric particulates was carried out moreover in sites near industrial plants of great environmental concern.

Transboundary transport of atmospheric pollutants through the eastern alps

Abstract Some preliminary analyses have shown that the Brenner Pass can be important in the transport of atmospheric pollutants through the Alpine chain, due to either breeze circulation or inflows of air masses. In one cross-section of the valley near the pass, meteorological and chemical measurements were taken, starting in 1986. The local breeze was studied but it was recognized to be of minor importance. The transport of pollutants through the pass was, on the whole, modest except during some inflows that only lasted for a few days. Meteorological situations have been registered when windborne pollutants are transported either to or from Italy, as was recognized from the trajectory analysis. The air masses coming in from central and eastern Europe generally contain higher concentrations of SO2 than NO2, while the opposite is true when the air masses originate in the Po Valley where the large use of methane enriches the air with NO2.

Acoustic sounding of land and sea breezes

Sodar measurements have been made at La Spezia, Italy during land- and sea-breeze conditions. The backscatter returns are discussed qualitatively, including their relation to the vertical structure of the boundary layer as revealed by vertical soundings of wind and temperature. During inversion conditions, the sodar signals may be difficult to interpret especially when there is a land breeze flowing over irregular terrain.

A study of greenhouse gases and air trajectories at Plateau Rosa

SummaryThe attention paid to changes in atmospheric concentrations of greenhouse gases has recently increased, with particular regard to the relationships between variations of their annual trends and of their shorter-period fluctuations on the one hand, and some geophysical and biological natural processes (like atmospheric transport, volcanic eruptions, ENSO events, seasonal vegetation cycles, and so on) on the other hand. Careful analysis and interpretation of the above relationships, in fact, can often disclose unknown mechanisms acting on modulations of these gases and make it possible for us to better understand the contributions made to them by natural causes, contrasted with anthropogenic ones. This paper presents and discusses the results of a series of CO2 air concentration data, measured at Plateau Rosa (3480 m a.s.l.—Italian Western Alps) over a period of about four years, and correlated with atmospheric transport processes on synoptic scale. These results have shown the leading role played by some kinds of atmospheric circulation patterns in creating situations of not fully mixed air streams (and, as such, not representative of background conditions) and have also suggested a «meteorological» selection scheme for CO2 data to be used in evaluating more reliable annual trends.

Computing the flux of moisture from net radiation and soil wetness

A study has been made of the time evolution of the flux of moisture E over grassland. The parameterization of E has been examined in order to formulate an equation depending on the net radiation flux and on bulk parameters which depend on the daily average meteorological situation and soil conditions. In particular the gradient of soil moisture has been recognized as playing a fundamental role in the time evolution of E(t). A time-dependent equation is proposed to compute in a statistical sense the irrigation needs or to forecast the hourly values of E(t), the maximum value E0 and the time at which this maximum happens.

Remote Sensing of Stability Conditions during Severe Fog Episodes

It is a widely recognized fact that the occurrence of most severe air pollution episodes is connected to deep fog layers. This happens not only as a mere consequence of that particular thermodynamic stratification of the lower troposphere wich establishes under fog conditions and reduces vertical dispersion, but also because fog takes usually place during the cold season, when a substantial contribution from low level domestic, uncontrolled sources is added to the industrial ones. The increased pollution background due to the former makes it necessary to exert stricter controls on the latter, through strategies of emission reduction, desulphuration, temperature increase of flue gas, burning of low sulphur content fuel, and so on.

PIXE as a tool for elemental and size analysis of power station particulate emissions

Abstract Particulate matter released into the stack effluents of a large oil-fired and a coal-fired power station was characterized. The main emission elements, together with their concentrations and size distributions, were determined by means of the PIXE analytical technique. The morphological and mineralogical characteristics of the single particles were established using SEM-EDAX and XRD techniques.

Forecasting of Fumigation Episodes in the PO Valley

Air quality management in the Po Valley needs particular attention. It is the more densely populated region of Italy and there are various and complex pollution sources in the area. It experiences a complex climatology. Winds, which are induced by the surrounding Alps and Appennines, are generally weak and with large shears.