Surface energy balance in a suburban area of the megacity of São Paulo - Seasonal variation and closure

Abstract

The study addressed the seasonal variation and closure of the Surface Energy Balance (SEB) in a suburban area of the Megacity of São Paulo. This area consists of a combination of buildings and vegetation classified into local climate zone typologies 5 (38.5%), 6 (26.7%), and 8 (11.2%), along with areas exclusively with vegetation representing 12.1%. The investigation is based on high-quality measurements taken during February (rainy summer) and August (dry winter) between 2013 and 2015. The greatest seasonal variation was observed in latent heat flux, reaching 64.7% for daily values and 63.9% for daytime values. The smallest was observed by sensible heat flux, reaching 20.3% and 24.1%, respectively. This suggests that seasonal variation in temperature and humidity plays a crucial role in energy distribution, generating uncertainties in the closure of the energy balance. The largest difference between energy input and output was seen in August, reaching 25% for daily values and 45% for daytime values. The gap saw in closure is consistently larger in winter. The results contributed to improving understanding of energy exchanges in the surface-canopy-atmosphere system, being essential in the development of more correct meteorological and hydrological models.