The sky view factor (SVF) is an important radiometric parameter for assessing the canopy energy budget of urban areas. There are several methods to determine the SVF observationally. The most common is taking a photo with a digital camera equipped with a fish-eye lens and then converting ratio of sky area to canopy area into SVF. However, most urban canopy models use this variable as derived from idealized canopy geometry. To evaluate the effect of inputting observed SVFs in numerical models, we evaluated a mesoscale model’s performance in reproducing surface wind and surface temperature when subjected to different ways of SVF prescription. The studied area was the Metropolitan Area of São Paulo (MASP) in Brazil. Observed SVFs were obtained for 37 sites scattered all over the MASP. Three simulations, A, B, and C, with different SVF and aspect-ratio prescriptions, were performed to analyze the effect of SVF on the urban canopy parameterization: Simulation A (standard) used the original formulation of the Town Energy Budget (TEB) model, computing the SVFs from the aspect-ratios; Simulation B used the observed SVFs, but keeps aspect-ratios as original; and Simulation C used the aspect-ratios computed from observed SVFs. The results show that in general inputting observed SVFs improves the model capability of reproducing temperature at surface level. The comparison of model outputs with data of regular meteorological stations shows that the inclusion of observed values of SVFs enhances model performance, reducing the RMSE index by up to 3 ${}^{\circ }$C. In this case, the model is able to better reproduce the expected effects in the wind field, and consequently the temperature advection, of the urban boundary layer to a large urban area. The result of Simulation C shows that the surface wind and temperature intensity for all urban types is higher than those of Simulation A, because of the lower values of the aspect ratio. The urban type with high density of tall buildings increase up to 1 $\mathrm{m}{\mathrm{s}}^{-1}$ in the wind speed, and approximately 1 ${}^{\circ }$C in temperature, showing the importance of a better representation of the urban structure and the SVF database improvement.

In the context of the impact of urbanization on climate change, this work aims to evaluate the sensitivity of the thermal and radiative properties of building surfaces in urban areas to the urban heat island intensity, a local scale meteorological phenomenon. For this, variations of albedo values, emissivity, thermal conductivity and heat capacity of roofs, streets and walls were simulated through an urban scheme coupled with the BRAMS mesoscale atmospheric model for the metropolitan area of São Paulo, considering two main urban types. The simulations show that, in general, looking for cold surface situations, the change of building material can contribute to a reduction of up to 3 °C for São Paulo. In addition, the role of orientation and the typological characteristics of constructions should be taken into account. In this sense, it is expected that this work guides civil engineers and builders to search for new materials in order to reduce the effects of urbanization on the local climate.

The Journal of Aerospace Technology and Management is a techno-scientific publication serialized, edited, and published by the Institute of Aeronautics and Space (Instituto de Aeron

The Alcântara Launch Center is located near the Brazilian Northeastern coastline downwind of a cliff 40 m high. Furthermore, the flow transition from open ocean past by the coastline generated an internal boundary layer (IBL) due to the roughness step change. The flow is mainly driven by the Trades, although the interaction with land-sea circulation may not be negligible. These features modify the ocean wind ocean profile as measured over land at the coastal site. We present here an ongoing research aiming to characterize the wind profile, which would serve as input flow profile in wind tunnel experiments and for gas dispersion studies. We analyzed the data of wind speed and direction collected between 1995 and 1999 by six aerovanes mounted in a 70-m height tower located about 200 m downwind the cliff. To study the diurnal and annual patterns of the wind profile the stored mean values of 10 min were monthly and hourly averaged. A simple estimate of the IBL height by assuming a dependence on the upwind distance of the shore as suggested in the literature were carried out. IBL height ranges from 30 to 40 m at tower location and being higher between 10 and 15 Local Time (LT). The wind profile power-law shows an alpha exponent greater (up to 0.35) than those encountered in the literature (about 0.10–0.11) for open ocean wind profile. The step change in the surface roughness cannot alone explain such a change in the alpha exponent. Other causes such as temperature step change and the cliff elevation certainly play a role to be still addressed.