R.Manasseh Fluid Dyn Papers
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Many major cities like Sydney have significant air pollution problems caused by a mixture of photochemical smog and other products of motor vehicle and industrial emissions (Carras and Johnson 1982). The meteorological situation in coastal cities is complicated by the presence of land- and sea-breeze effects, which can make attempts at forecasting pollution levels more difficult. Hitherto, most data in Sydney has been based on ground-based or sounding data which cannot give a full picture of the dynamical effects occurring throughout the urban air mass, particularly just offshore.
The use of aircraft and gliders in studying sea-breezes offers the possibility of more comprehensive measurements (for some earlier examples, see Simpson 1994). LIDAR studies (eg. Nakane & Sasano 1986; Banta et al 1993) and Doppler radar studies (eg. Laird et al 1995) can reveal the vertical structure of the front. Aircraft surveys may, in addition, simultaneously measure local fluid and thermodynamical variables as well as chemical tracers. Aircraft surveys are, however, constrained by a finite transit speed and, in ubran areas, by air traffic control.
The present observations are part of a campaign of aircraft flights intended to provide some preliminary airborne data on Sydney's local wind and pollutant regime, with reference to the land- and sea-breeze system. This campaign was carried out during February and March 1994.
Recent sea-breeze studies utilizing the same aircraft of the present study (Kraus et al 1990; Finkele et al 1995) were carried out over a flat, regular, rural coastline. In Sydney, the effects of complex topography are expected to be significant. The influence of an irregular coastline on the vertical structure of sea-breeze has been noted in a number of numerical and observational studies (e.g. Abbs 1983; Laird et al 1995). The effect of complex topography on local winds was emphasized in the numerical study of Sha et al (1996). Finally, over a city, the presence of urban-sourced pollutants could provide a tracer of air-mass movements.
R.Manasseh Fluid Dyn Papers
R.Manasseh Fluid Dyn Home