Air pollution in big cities is one of the principal problems facing our society. There are well documented cases of critical situations in large metropolises located in a tropical latitudes.
The study of temperature inversions is essential due to the fact that these processes cause unfavourable meteorological conditions that are especially dangerous for a large city. In the last few years, only one article has been published that analyses the thermal inversions in the Metropolitan Area of Guadalajara (MAG) during 1980 (Jauregui et al., 1992). The MAG consists of four districts: Guadalajara, Tlaquepaque, Tonala and Zapopan in the state of Jalisco. It is the greatest regional centre in western Mexico, covering an area of approximately 1461.6 km2 and has recently been undergoing an intense urbanisation, near 4 millions persons.
The statistical parameters were determined from data of a radiosonde probe located in the MAG, for the period 1991-1996. These represent the principal characteristics (stratum thickness, intensity and thermal gradient of the layer) of this phenomenon and using spectral analysis methods it was possible to identify latent periodicities in the dynamic processes that influence the formation of inversions in the boundary layer above the MAG. A result of more than 86.5% cases was achieved with thermal inversions in it. The annual process of this phenomenon was divided by its characteristics, such as the height of its base and it's formation mechanism and within these, it was possible to observe a notable seasonal dependency. The spectral analysis indicated that the predominant contributions in the formation of the inversions during the year were the synoptic-scale atmospheric processes. Absolute extreme cases of the initial series were studied, as well as common statistical analysis. The results obtained can be used to specify the vertical structure of the "heat island" above the MAG or to investigate the influence of thermal inversions on the formation of critical air pollution situations on a large industrial city, located in a tropical zone.
Jaureguí, E.,1992. Aspects of Heart-Island Development in Guadalajara, México. Atmosphere Environment, Vol. 26B, N3,pp. 391-396.