Effects of urbanization on winds over Dar es Salaam
This study sought to investigate the effect of urbanization on urban winds over Dar es Salaam based on observed maximum temperature, minimum temperature, wind speed and wind direction between the periods 1981 to 2012 while Population and Global Data Assimilation System (GDAS) data covered the period 2002 -2012 and 2004 -2012 respectively. Single mass curve was used for data quality control while time series, wind rose and correlation analysis were used to achieve the objectives of the study. Data quality control indicated that the data-sets were homogeneous. Results showed that population, maximum temperature, minimum temperature and wind speed at 0600Z and 1200Z were increasing with minimum temperature showing most significant increase in trend with coefficient of determination at 82.8%. The change in minimum temperature was observed to be higher than the change in maximum temperature owing and attributed to urbanization effects. Temperature was highly correlated with population with values above 0.5 which were significant. A Comparison of wind speeds between current and past years showed an increasing pattern. Results from wind roses analysis showed that the predominant winds were mainly south easterlies and their direction was noted to have slightly changed between the two periods considered. The study noted that modification of both wind speeds and direction was a result of horizontal thermal gradients due to the urban heat island and less due to urbanization. Therefore, urban planners should consider modification due to urbanization for proper planning of residential and industrial places to ensure thermal comfort.