Resumen

JAUREGUI, E.. Possible impact of urbanization on the thermal climate of some large cities in México. Atmósfera [online]. 2005, vol.18, n.4, pp.249-252. ISSN 0187-6236.

Urbanization has been the dominant demographic trend during the second half of the 20th century in México. In 2000 there were 69 cities with more than 100,000 inhabitants of which 9 of them exceeded one million population, totalizing 53.4 million. Using time series of mean monthly temperature for about a dozen available stations, this paper sets out to examine temperature changes occurring during the late 20th century. Since it is well established that urban warming is mainly a nocturnal phenomenon minimum temperature series were selected after a test for homogeneity. Trend analysis was applied to the minimum temperature series and a linear regression coefficient was obtained. Tests of significance were performed. Most of the positive trends proved to be significant (>90%). Although temperature trend variability amongst the individual cities was large (from 0.02°C/decade to 0.74 °C/decade) average temperature increase in large (>10⁶ inhabitants) cities was (0.57 °C/decade) considerably higher than that corresponding to medium size urban centers where on the average temperature increase was 0.37 °C/decade. These temperature increases express not only the urbanization effect but also that due to global climate change (of the order of 0.07 °C/decade) and natural variability. In concluding it may be said that increasing urbanization in México has originated a positive trend in urban temperatures which has implications for human comfort and health.

Palabras llave : Heat island; urban warming; México.