The urban heat island is a well-documented physical phenomenon in large tropical urban areas. High urban/rural temperature contrasts are more likely to occur in large cities located in interior valleys, such as Deli (Padmanabhamurty, 1986) or Mexico City (Jauregui, 1992-97). The effect of heat islands has been more extensively explored for Mexico City than for Guadalajara (Jauregui,1992), both of which are located in inland valleys in tropical Mexico.
The results of the investigation of heat islands in Metropolitan Area of Guadalajara (MAG) are discussed. 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. This metropolis is located in Southwest of the central Mexican plateau at 20º39'54" N and 103º18'42" W. It is surrounded by the mountains. Its altitude is over 1500 m above sea level and it is approximately 270 km from the coast. The surface of the urban zone also presents some significant variations, for example the difference between the north-eastern and eastern part of the MAG is 38 metres. The structure of the time sequences of the temperature fluctuations is studied with a cross spectral analysis. The data were obtained from three meteorological stations, two of which are within the city limits and one in the suburban zone. Statistically supported oscillations of the mentioned meteorological elements have been detected with periods from 3-5 days to 22 years.
The trend of the temperature growth at the stations in the urban zone was detected as: 0.017°C/yr. for Tmax and 0.049°C/yr. for Tmin. A small trend at the station in the suburban zone was also detected, which has the longest sequences of observations. The latter is probably due the fact that it close to the location of this station. An urban cool island was detected in the wet season. As a result of our analysis, the relationships between the urbanistic factors (such as population and construction areas) and the variations of temperature, which determine the climate of the big city, were detected.
Reference.
Jauregui, E., L. Godines and Crus. Aspects of the heat island in Guadalajara, Mexico.- (Submitted to Urban Atmosphere). -1992-. P. 391-396.
Jauregui, E. Mexico city’s urban heats island revisited. // Erdkunde -1993- Band 47, -P. 185-195.
Jauregui, E. Aspects of day- time urban heat island development in Mexico City. // Intern. Symposia. on Environ. and Biometeor. -1995- Beijing.
Jauregui, E.Climates of tropical and subtropical cities.// in the book”Climates and Societies” - Kluwer Academic Publishers –1997-. P. 361-373.
Padmanabhamurty, B. Aspects of urban climates in India, in Procced. Tech. Conf. on Urban and Building Climatology. Mexico City. // WMO. 652. (T.R. Oke de.), Geneva -1986- P. 136-165.