Observational Investigation of the Statistical Properties of Surface-Layer Turbulence in a Suburban Area of São Paulo, Brazil: Objective Analysis of Scaling-Parameter Accuracy and Uncertainties

Sensible, latent heat and store energy fluxes in the suburban São Paulo Megacity: seasonal and interannual variations and empirical modeling

“…According to Ferreira et al, 12 within a 1-km radius area centered in the PM IAG, the surface is occupied by 25.4% of trees, 64.1% of impervious building and streets, 7.3% by grass, shrub, and scrub, and 2.3% of water, indicating a suburban land use around the PM IAG (Figure 1). The 1-km radius area is characterized by Local Climate Zone classification LCZ 6, confirming the earlier classification performed by Ferreira et al, 12 Oliveira et al, 17 and Silveira et al 19 The topography is gently sloping towards the Pinheiros river valley, with elevations ranging from 718 m in the north to 782 m in the south (Figure 1a). Most buildings have 3-4 floors, sparsely distributed, with an average height of 6.6 m (Figure 1b).…”

“…The maps indicated by 2009, 2010 and 2012 correspond respectively to the observations made on: May 18 to June 17, 2009 (Figure 2a); March 8 to June 30, 2010 (Figure 2c); and February 1 to November 30, 2012 (Figure 2e). The diurnal evolution of the UBL heights needed to estimate the footprint followed Silveira et al 19 The annual wind roses in Figure 2 correspond to wind observations made at PM IAG (Table 1) during the same period of turbulence measurements used to estimate the footprint. In general, the shape of footprint areas corresponding to 70% of contribution to the fluxes measured at PM IAG follows closely the most frequent wind direction distributions (Figure 2).…”

“…Most buildings have 3-4 floors, sparsely distributed, with an average height of 6.6 m (Figure 1b). According to Silveira et al 19 this area is characterized by roughness length equal to 0.52 ± 0.17 m and zero-plane displacement 15.0 ± 3.1 m. Therefore, between 2009 and 2012 turbulence measurements were performed majority at heights above the roughness sublayer (Table 1). Turbulence, net radiation, and air temperature measurements simultaneously cover the following periods: May…”

“…Typical of suburban areas, this behavior occurs because the land use in 36% of the measurements site area is occupied by vegetation, responding to the seasonal variation of moisture in the megacity of São Paulo. 12,17,19 Throughout 2012, the amplitude of H and LE vary proportionally to 𝑄 * . Both H and LE daytime maxima occur 1 hour after 𝑄 * .…”

“…Besides Webb correction, several quality control procedures were applied to estimate the 𝐻 and 𝐿𝐸 to remove glitches, linear trends, tower-blocking effects, signal saturation caused by rain and dew deposition on sonic transducers and gas analyzer windows, and to enforce skewness and kurtosis thresholds and stationarity. 19 About 40% of the 30-min blocks were discard due to all these unwanted effects.…”