Severe Weather Caused by Heat Island and Sea Breeze Effects in the Metropolitan Area of São Paulo, Brazil

Vemado, Felipe; Filho, Augusto José Pereira

doi:10.1155/2016/8364134

Cited by 41 publications

(49 citation statements)

References 36 publications

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“…Another consideration that is brought to the analysis relates to the high flash rates observed over the urban area, which possibly explains the high flash density observed in other studies at this region [ Bourscheidt et al, ; Naccarato et al, ]. The higher activity near to the center of the urban area is possibly related to the penetration of the sea breeze as well, which reaches the urban area in the early afternoon, resulting in deep convection [ Vemado and Pereira Filho, ], as described earlier.…”

Section: Discussionmentioning

confidence: 98%

“…The figure also indicates a northwest flow associated to frontal systems and to the SACZ (a persistent unstable area associated with stationary frontal systems) that may interact with sea breeze by bringing hot, moist air over the studied region, increasing instability and contributing to the amplified lightning activity observed over the urban area. This may explain the existence of a negative DDA in both the southeasterly and northwesterly flows during the summer (Figure a) and is in agreement with the observations of Vemado and Pereira Filho []. Additionally, there is a main northeasterly flow related with the South Atlantic High trades that is also expected to influence the storm onset and the CIT pattern.…”

Section: Discussionmentioning

confidence: 99%

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The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)

2016

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Eleven years of lightning data from the Brazilian Integrated National Lightning Detection Network were used to analyze the effects of the urban heat island (UHI) of Sao Paulo on lightning activity, extending the investigation of previous works. Cloud‐to‐ground lightning data were analyzed in both spatial and temporal perspectives, using different approaches: flash density, flash rate, thunderstorm hours (TH), and the cell initiation technique (CIT), which aims to identify the onset of thunderstorms. Land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) was used to analyze the UHI evolution over the years. MODIS data were validated using ground stations, distributed within the urban area. Different time intervals (seasonal and intraday) were used in an attempt to separate local convective systems from synoptic‐scale events. The results indicate significant effects of the UHI (using LST) on THs and CIT. The CIT showed a nearly ring pattern, especially during the afternoon (14:00–18:00 LT) of summer months, reinforcing temperature contrast as a condition for storm initiation. The results also suggest an amplification of the UHI effects on thunderstorm activity by local factors (sea and country breeze, synoptic events, and terrain). Higher flash rates were also observed throughout the urban region, which influences the lightning density. Temporal analysis indicates that minimum temperature and lightning activity increase in wintertime. In summary, the results agree with previous studies about the UHI and indicate its importance on lightning occurrence, especially by increasing the temperature contrast and the instability in these regions.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)

2016

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“…The time evolution of the UBL in the MRSP during the summer and winter campaigns of the MCITY BRAZIL Project are indicated in Figure . In these two periods the UBL evolution respond to the cloudiness pattern associated to the following synoptic and mesoscale systems: (a) Upper Air Trough, (b) Cold Front (de Jesus et al, ; Foss et al, ), (c) Bolivia High (Lenters & Cook, ), (d) Upper Tropospheric Cyclonic Vortex (Kousky & Gan, ; Mishra et al, ; Mishra et al, ), (e) Sea Breeze (Freitas et al, ; Oliveira et al, ; Ribeiro et al, ; Vemado & Pereira Filho, ), (f) Post‐Frontal High‐Pressure System (de Jesus et al, ; Foss et al, ), and (g) South Atlantic Subtropical High (Sun et al, ).…”

Section: Ubl Propertiesmentioning

confidence: 99%

Rawinsonde‐Based Analysis of the Urban Boundary Layer in the Metropolitan Region of São Paulo, Brazil

Sánchez

Oliveira

Varona

et al. 2020

Earth and Space Science

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The main features of the urban boundary layer in the metropolitan region of São Paulo are estimated based on rawinsondes carried out (a) every 3 hr in two 10‐day field campaigns of the MCITY BRAZIL Project during the summer and winter of 2013 and (b) regularly once per day and continuously for 4 years from 2009 to 2013. On average, the boundary layer height showed a daytime maximum of 1476 ± 149 m in summer and 1122 ± 168 m in winter campaigns. The differences are related to seasonal variations in the (a) buoyancy flux at the surface, which was 30% larger in summer (4.7 ± 0.6 MJ m−2 day−1), and the (b) static stability of the free atmosphere, which was 15% smaller in summer (3.3 ± 0.1 K km−1). The average nighttime boundary layer height, estimated from equilibrium empirical expression, indicated maximum of 126 ± 13 m in summer and 122 ± 10 m in winter campaigns. The presence of a low‐level jet was identified in 80% of the field campaign nights, with intensity varying from 2.7 to 14 m s−1 and height ranging from 95 to 962 m. The nighttime residual‐mixing layer is well estimated using the air temperature gradient method and is a good indication of the maximum vertical evolution of the previous daytime boundary layer. The monthly average maximum boundary layer height varied from a minimum of 1,061 ± 77 m in September to maximum of 1,632 ± 96 m in May.

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“…In general, the incoming sea breeze interacts with the warmer and drier (urban) heat island of São Paulo, producing very deep convection with heavy rainfall, wind gusts, lightning and hail 5 (Vemado and Pereira Filho, 2016;Machado et al, 2014;Pereira Filho, 2012 , February is the warmest month with 22.4…”

Section: Description Of Study Areamentioning

confidence: 99%

Rainfall retrieval with commercial microwave links in São Paulo, Brazil

Gaona¹,

Overeem²,

Raupach³

et al. 2017

Preprint

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Abstract. In the last decade there has been a growing interest from the hydrometeorological community regarding rainfall estimation from commercial microwave link (CML) networks. Path-averaged rainfall intensities can be retrieved from the signal attenuation between cell phone towers. Although this technique is still in development, it offers great opportunities for the retrieval of rainfall rates at high spatiotemporal resolutions very close to the Earth's surface. Rainfall measurements at high spatiotemporal resolutions are highly valued in urban hydrology, for instance, given the large impact that flash floods exert on 5 society. Flash floods are triggered by intense rainfall events that develop over short time scales.Here, we present one of the first evaluations of this measurement technique for a subtropical climate. Rainfall estimation for subtropical climates is highly relevant, since many countries with few surface rainfall observations are located in such areas.The test bed of the current study is the Brazilian city of São Paulo. The open-source algorithm RAINLINK was applied to retrieve rainfall intensities from (power) attenuation measurements. The performance of RAINLINK estimates was evaluated 10 for 5 of the 250 CML in the São Paulo metropolitan area for which we received data, for 81 days between October 2014 and January 2015. We evaluated the retrieved rainfall intensities and accumulations from CML against those from a dense automatic gauge network. Results were found to be promising and encouraging, especially for short links, for which high correlations (> 0.9) and low biases (∼30% and lower) were obtained.

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Severe Weather Caused by Heat Island and Sea Breeze Effects in the Metropolitan Area of São Paulo, Brazil

Cited by 41 publications

References 36 publications

The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)

The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)

Rawinsonde‐Based Analysis of the Urban Boundary Layer in the Metropolitan Region of São Paulo, Brazil

Rainfall retrieval with commercial microwave links in São Paulo, Brazil

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