, Volume 104, Issue 1-2, pp 43-56
Date: 22 Aug 2010

Anthropogenic heat in the city of São Paulo, Brazil

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Abstract

The main goal of this work is to describe the anthropogenic energy flux (Q F) in the city of São Paulo, Brazil. The hourly, monthly, and annual values of the anthropogenic energy flux are estimated using the inventory method, and the contributions of vehicular, stationary, and human metabolism sources from 2004 to 2007 are considered. The vehicular and stationary sources are evaluated using the primary consumption of energy based on fossil fuel, bio fuel, and electricity usage by the population. The diurnal evolution of the anthropogenic energy flux shows three relative maxima, with the largest maxima occurring early in the morning (∼19.9 Wm−2) and in the late afternoon (∼20.3 Wm−2). The relative maximum that occurs around noontime (∼19.6 Wm−2) reflects the diurnal pattern of vehicle traffic that seems to be specific to São Paulo. With respect to diurnal evolution, the energy flux released by vehicular sources (Q FV) contributes approximately 50% of the total anthropogenic energy flux. Stationary sources (Q FS) and human metabolism (Q FM) represent about 41% and 9% of the anthropogenic energy flux, respectively. For 2007, the monthly values of Q FV, Q FS, Q FM, and Q F are, respectively, 16.8 ± 0.25, 14.3 ± 0.16, 3.5 ± 0.03, and 34.6 ± 0.41 MJ m−2 month−1. The seasonal evolution monthly values of Q FV, Q FS, Q FM, and Q F show a relative minimum during the summer and winter vacations and a systematic and progressive increase associated with the seasonal evolution of the economic activity in São Paulo. The annual evolution of Q F indicates that the city of São Paulo released 355.2 MJ m−2 year−1 in 2004 and 415.5 MJ m−2 year−1 in 2007 in association with an annual rate of increase of 19.6 MJ m−2 year−1 (from 2004 to 2006) and 30.5 MJ m−2 year−1 (from 2006 to 2007). The anthropogenic energy flux corresponds to about 9% of the net radiation at the surface in the summer and 15% in the winter. The amplitude of seasonal variation of the maximum hourly value of the diurnal variation increases exponentially with latitude.