A influência da urbanização no clima da cidade de Campina Grande-PB.

Abstract

Expansion of cities has several impacts on urban environment caused by anthropogenic activities, and so it may develop climate variability. This study attempts to assess the effect of urbanization on the climate in Campina Grande city (7o12’S; 35o51’W; 508 m a.s.l), Brazil. Monthly data of air temperature (maximum, minimum and mean), sunshine, relative humidity, rainfall, atmospheric pressure, wind speed and UNEP index (P/ETp) for the 1963 to 2004 time period were used. In order to detect the period of abrupt changes the method of cumulative departures from the long-term mean has been adopted. Thus, two study sub period were established as following: intense pre- urban (1963-1985) and intense post- urban (1986-2004). For each climatic variable during the study periods it was obtained some statistical parameters such as mean, standard deviation, coefficient of variation (CV) and serial autocorrelation. Difference between means of intense pre- urban and intense post- urban time period for all climatic variables was evaluated by t-Student test. Also, it was used the Mann-Kendall test to assess the trends of the time-series during the 1963 to 2004 time period. Reference evapotranspiration was obtained by Hargreaves method for finding UNEP index (P/ETp). Maximum, mean and minimum air temperature presented increased trend (statistically significant at p<0.01) by Mann-Kendall test. Relative humidity showed decreasing trend also statistically significant at p<0.01. However, rainfall, class “A” pan evaporation and UNEP index had not statistically significant trend. The rainfall intra-annual variability in Campina Grande city, exp ressed as a CV, is very high, which ranged from 30 to 89% during analyzed period. On average, the rainfall annual variability is about 30% of the intra-annual variability. Air temperature (maximum, mean and minimum) demonstrated the nature persistence in the time-series by autocorrelation coefficient at the first lags.