Spatial distribution in long-wave radiation flux in São Paulo City, Brazil


Gael Clemente Jean and Alfonso K. Iñárritu

The long-wave radiation (L*) in the urban canyons in São Paulo City, Brazil was observed through the use of a Pyrgeometer PIR model (Precision Infrared Radiometer by Eppley) and a Net Radiometer LITE model (NRLITE by Kipp & Zonen). A simple scheme to estimate the upward longwave radiation (L↑) from observations of the net all-wave radiation (Q*) is evaluated using a 2,200 km dataset. The instruments are set up on a mobile platform, which moves through the bottom of the canyons. The results are compared with the observed wall surface apparent temperatures. The thermal and radiation patterns are verified along the traverses through the different land use types in typical nocturnal and diurnal periods during the dry season. This upward long-wave radiation parameterization is most sensitive to urban aspect ration effects on incoming long-wave radiation (L↓). Air temperature measurements and estimates of the convective QH flux between the atmosphere and urban buildings are also taken. For incoming long-wave radiation, even clear sky estimates show a large degree of scatter, the results degrade as intensive vehicle traffic periods are included.

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