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![Location of Sao Paulo state (SP) in Brazil and South America (detail). In the bigger map, the city of Sao Paulo (red dot), the ESP region (orange rectangle) and the CWSP region (yellow rectangle) are shown. The symbols (crosses, inverted triangles, etc.) represent different homogeneous rainfall regions. Figure adapted from Keller-Filho et al. [36].](profile/Jeferson-Machado/publication/332329909/figure/fig1/AS:746163502346241@1554910650159/Location-of-Sao-Paulo-state-SP-in-Brazil-and-South-America-detail-In-the-bigger-map.png)
Location of Sao Paulo state (SP) in Brazil and South America (detail). In the bigger map, the city of Sao Paulo (red dot), the ESP region (orange rectangle) and the CWSP region (yellow rectangle) are shown. The symbols (crosses, inverted triangles, etc.) represent different homogeneous rainfall regions. Figure adapted from Keller-Filho et al. [36].
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Drought is a natural hazard with critical societal and economic consequences to millions of people around the world. In this paper, we present the climatology of severe drought events that occurred during the 20th century in the region of Sao Paulo, Brazil. To account for the effects of rainfall deficit and changes in temperature at a climatic time...
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... state of Sao Paulo was divided in two zones of analysis, corresponding to homogeneous regions for precipitation probability distributions [36]: an eastern zone near the South Atlantic Ocean that presents a slightly more well distributed precipitation during the year (due to the influence of the ocean and the climatological displacement of cold fronts), hereafter called ESP (25 • S-22.5 • S; 50 • W-44 • W) and a zone that encompasses the central and western portions of the state (hereafter CWSP-23 • S-20 • S; 53 • W-47 • W). These areas are marked in Figure 1. Atmospheric variables were computed as an areal average over these regions, and the obtained SPEI is considered a mean value for the region. ...
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... SPEI 48, the observed duration and severity are slightly larger, and for all three indicators CRU presents a higher dispersion than the reanalysis. It is evident in the time series of events per decade according to SPEI 3 and 12 that severe droughts became more frequent over CWSP throughout the 20th century ( Figure 10). The trend is confirmed by the regression coefficients (Table 3). ...
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... between the SPEI time series obtained from ERA20C and CRU (Figures 2, 5 and 8) might occur due to the representation of basic atmospheric variables in the reanalysis. In order to discuss this, Figure 11 presents the annual mean of accumulated precipitation and air temperature in both datasets. Comparing Figure 11a with Figure 2e,f,h,i indicates that the subestimation of a severe drought event in the 1950s in Sao Paulo city by ERA20C may be associated with overestimated precipitation and lower temperatures during this period, compared to CRU. ...
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... order to discuss this, Figure 11 presents the annual mean of accumulated precipitation and air temperature in both datasets. Comparing Figure 11a with Figure 2e,f,h,i indicates that the subestimation of a severe drought event in the 1950s in Sao Paulo city by ERA20C may be associated with overestimated precipitation and lower temperatures during this period, compared to CRU. However, the fact that drought was overestimated in ERA20C during the 1930's and 1980's, when the reanalysis also presented more precipitation and even lower mean temperatures, suggests that this relationship is not strongly direct. ...
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... behavior was observed over the ESP region. Over the CWSP region, the annual mean temperature in ERA20C is systematically colder than in CRU (Figure 11d), so differences in the SPEI should be related to precipitation. Indeed, it can be seen that ERA20C overestimation in severe events of the 1940's and 2000's (Figure 8b,c,e,f) coincide with less precipitation in the reanalysis (Figure 11c). ...
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... the CWSP region, the annual mean temperature in ERA20C is systematically colder than in CRU (Figure 11d), so differences in the SPEI should be related to precipitation. Indeed, it can be seen that ERA20C overestimation in severe events of the 1940's and 2000's (Figure 8b,c,e,f) coincide with less precipitation in the reanalysis (Figure 11c). As in the case of ESP, the relationships between these variables and severe drought events are not so obvious, suggesting that other effects play a role on the determination of the index. ...
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... calculation using evapotranspiration equations that accounts for the effects of wind speed, and an evaluation of local representation of wind speed by the reanalysis are planned for a future paper. Figure 11 shows that there is a visible discrepancy between the variables' time series. Most notably, a large difference can be seen between the CRU and ERA20C mean temperature for region CWSP (Figure 11d). ...
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... 11 shows that there is a visible discrepancy between the variables' time series. Most notably, a large difference can be seen between the CRU and ERA20C mean temperature for region CWSP (Figure 11d). This difference clearly impacts the SPEI calculation because of the PET formula chosen. ...
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... leads us to ask whether at least one of these datasets -and if so, which one of them - shows that there is a visible discrepancy between the variables' time series. Most notably, a large difference can be seen between the CRU and ERA20C mean temperature for region CWSP (Figure 11d). This difference clearly impacts the SPEI calculation because of the PET formula chosen. ...
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This paper discusses some methodological aspects of the historical analysis of drought, particularly the trend assessment. The Standardized Evapotranspiration Index (SPEI) is widely used as a measure of drought condition. Since different SPEI thresholds allow classifying the risk into moderate, severe, and extreme, the drought occurrence becomes a...
Citations
... to delineate the intensities of drought based on the SPI. A negative SPI value indicates precipitation deficit (dry conditions) while a positive value shows precipitation excess (wet conditions)(Gozzo et al. 2019). ...
The cattle corridor in Uganda is known for its vulnerability to unpredictable rainfall patterns, recurring and severe droughts, all of which lead to water scarcity and crop failures. Therefore, to gain a deeper understanding of these drought characteristics, three districts were selected within the cattle corridor: Rakai in the South, Nakasongola in the Central, and Nabilatuk in the North. An analysis of historical and near future meteorological drought changes in the cattle corridor using SPI from the Coordinated Regional Downscaling Experiments (CORDEX) for the historical periods 1981–2010 and 2031–2060 (RCP 4.5 and 8.5). Trends in SPI values were assessed using the Sen slope estimator and Mann–Kendall test at 0.05. Results suggest ongoing drought occurrences, even during traditionally wet periods, especially during La Niña period. Nakasongola district experienced more frequent droughts, with 25 in the historical period and 26 in the near future compared to Rakai and Nabilatuk districts. Historically, the districts had average drought spans of 7–9 months and maximum spans of 23–36 months. Under RCP4.5, durations ranged from 6 to 11 months (average) and 34–60 months (maximum), while under RCP8.5, from 8 to 13 months (average) and 23–41 months (maximum). Drought severity and duration were expected to increase across all districts, with Rakai district facing the longest historical (January 2007–December 2009) and the projected (April 2054–March 2059) droughts. Additionally, Nabilatuk showed negative and significant SPI trends historically (Sen’s slope = − 004, p value = 0.004). Hence, tailored interventions are crucial for stakeholders managing drought to build resilience.
... The city of Sao Paulo is affected by climate change and suffers increased temperatures. The results of a study by Gozzo et al. (2019) have foreseen an increase in temperature from 1 to 2 • C for the 2010-2030 period, from 2 to 3 • C for the 2040-2050 period, and of 4 • C for the 2080-2090 period. The increase in temperatures is often associated with an increase in high-intensity rainfall events and drought periods (WMO, 2021). ...
One of the most current and urgent challenges is making cities sustainable and resilient to climate change. From this perspective, Nature-Based Solutions (NBSs) are well-recognized strategies for stormwater control and water cycle restoration. Urban trees are an example of NBS. However, the high degree of soil sealing typically found in urban environments limits natural processes such as infiltration and hinders the water and nutrient supply for proper root development, which weakens tree stability. Permeable pavements at the base of urban trees, on the one hand, facilitate infiltration, which helps runoff control, and on the other hand, improve stormwater retention and soil humidity, which enhance root feeding.
This paper proposes an analytical-probabilistic approach to estimate the contribution of permeable pavements to stormwater management. The equations developed in this study relate the runoff probability to the storage volume, the infiltration rate into the underlying soil, and the average values of the hydrological variables in the input. The model allows us to select different runoff thresholds and considers the possibility that residual volume from previous rainfall events prefills the storage capacity.
An application to a case study in Sao Paulo (Brazil) has been presented. It investigates the influence of the different parameters used in the model on the results. The comparison of the outcomes obtained using the developed equations with those obtained from the continuous simulation of measured data confirmed the effectiveness of the proposed analytical-probabilistic approach and the suitability of using permeable pavements at the base of urban trees for improving stormwater retention.
... Droughts are a natural phenomenon characterized by a continuous persistence of precipitation deficit, which occurs in almost all climate zones, including those with high precipitation rates, such as Amazonia [4]. Prolonged periods of drought cause innumerable damages, such as losses in agriculture and livestock, contamination of waters, reduction of water availability for daily consumption and water energy generation, and environmental risks of fires [5,6]. Due to climate change and increasing temperatures, droughts are expected to increase in frequency and duration [7,8]. ...
Drought events are critical environmental threats that yield several socioeconomic impacts. Such effects are even more relevant for South America (SA) since different activities essential for the continent, such as agriculture and energy generation, depend highly on water resources. Thus, this study aimed to evaluate future changes in precipitation and hydrological drought occurrence in SA through climate projections from eight global climate models (GCMs) of CMIP6. To this end, statistical downscaling was applied to the projections obtained using the quantile delta mapping technique, and the method proved to be efficient in reducing systematic biases and preserving GCMs’ trends. For the following decades, the results show considerable and statistically significant reductions in precipitation over most of SA, especially during the austral spring, with the most intense signal under the SSP5-8.5 forcing scenario. Furthermore, GCMs showed mixed signals about projections of the frequency and intensity of drought events. Still, they indicated agreement regarding the increased duration and severity of events over the continent and a substantial proportion of moderate and severe events over most of Brazil during the 21st century. These results can be helpful for better management of water resources by decision-makers and energy planners.
... Droughts are a natural phenomenon characterized by a continuous persistence of precipitation deficit, which occurs in almost all climate zones, including those with high precipitation rates, such as the Amazonia [4]. Prolonged periods of drought cause innumerable damages, such as losses in agriculture and livestock, contamination of waters, reduction of water availability for daily consumption and water energy generation, and environmental risks with fires [5,6]. Due to climate change and increasing temperatures, droughts are expected to increase in frequency and duration [7,8]. ...
Drought events are evident effects of climate change around the globe and yield several socio-economic impacts. Such effects are even more relevant for South America (SA) since different activities essential for the continent, like agriculture and energy generation, depend highly on water resources. Thus, this study aimed to evaluate future changes in precipitation and hydro-logical droughts occurrence in SA through climate projections from eight global climate models (GCMs) of CMIP6. To this end, statistical downscaling was applied to the projections with the Quantile Delta Mapping technique, and the method proved to be efficient in reducing systematic biases and preserving GCMs’ trends. For the following decades, the results show considerable and statistically significant reductions in precipitation over most of SA, especially during the austral spring, with the most intense signal under the SSP5-8.5 forcing scenario. Furthermore, GCMs showed mixed signals about projections of the frequency and intensity of drought events. Still, they indicated agreement regarding the increase in duration and severity of events over all of SA and a substantial proportion of moderate and severe events over most of Brazil during the 21st century. These results can be helpful for better management of water resources by deci-sion-makers and energy planners.
... Morello et al., 2020), o Índice de Porcentagem da Normal (Gois, 2005) (Joetzjer et al., 2013;Chaudhari et al., 2019), o Pantanal (Marengo et al., 2021), o Nordeste (Nascimento et al., 2017;Brito et al., 2018) e o Sudeste e Sul do país (Sobral et al., 2018;Terassi et al., 2018;de Paiva Lima et al., 2022). Especificamente para o estado de São Paulo, o SPI e o SPEI (uma adaptação do SPI que considera no cálculo do balanço hídrico a temperatura do ar e o processo de evapotranspiração) vêm sendo utilizados na caracterização de eventos extremos de seca (Blain e Brunini, 2005;Coelho et al., 2016;Oliveira et al., 2022), e no estudo das tendências de ocorrência (Blain, 2012;Pereira et al. 2018;Gozzo et al., 2019a) e das forçantes climáticas de grande escala responsáveis por estes eventos (Gozzo et al., 2021;Gozzo et al. 2022). Siqueira e Nery (2017), descrevendo a climatologia do índice SPI sobre São Paulo entre 1970 e 2010, obtiveram diferentes valores médios do SPI sobre o Estado: ao sul e leste, a média do índice é superior a 1,0, enquanto no centro-norte, mais seco, a média fica abaixo de 0,9, chegando a 0 no nordeste. ...
... A Figura 2 apresenta as climatologias anual e sazonais para o período de estudo Fonte: Elaborado pelos autores (2022). ...
... Agrupamento dos 5 primeiros modos rotacionados do SPI-1 com 2 grupos para (a) Agrupamento de Ward e (b) Agrupamento K-Médias. Elaborado pelos autores(2022). ...
Eventos extremos climáticos secos e chuvosos podem ser responsáveis por desastres naturais com grande impacto à população e ao meio ambiente. Neste trabalho, foi avaliado os padrões espaciais dominantes do Índice de Precipitação Padronizado (Standardized Precipitation Index - SPI), calculado a partir dos dados mensais de precipitação pluvial (1981-2020) no Estado de São Paulo, buscando regiões homogêneas deste índice, com apoio de análises estatísticas de Componentes Principais (ACP) e Agrupamentos (AA). Com base na ACP aplicada ao SPI-1 foram selecionadas as cinco primeiras componentes principais (CP) para rotação, que juntas explicaram 97,96% da variabilidade dos dados originais. Após a rotação dos eixos, a ACP indicou condições anômalas em todo o Estado, mais intensas no leste de SP em 42,05% (CP1) dos dados, e no oeste do Estado em 38,31% (CP2). Por sua vez, a AA apontou dois grupos homogêneos, um a leste e outro a oeste do Estado de São Paulo, com comportamentos espaciais concordantes aos dois primeiros modos da ACP rotacionada. Esse tipo de estudo é importante para a compreensão de como os eventos extremos de precipitação ocorrem no Estado de São Paulo e se distribuem espacialmente e temporalmente, ajudando no seu monitoramento e previsão.
... As the SPEI is based on the SPI, negative and positive values indicate drought and wetness, respectively [98]. Based on this, we followed the classification of SPEI by Alley [14]. ...
Drought and wetness events have become common due to global warming, warranting the need for continuous analysis and monitoring of drought and wet events to safeguard people’s livelihoods. In this study, the Standardized Precipitation Evapotranspiration Index (SPEI) was utilized to analyze the spatiotemporal characteristics of drought and wetness events in the coastal Savannah agroecological zone from 1981 to 2021. Climate data from 14 locations across the zone were used to characterize drought and wetness events at the 3 and 12 month timescales. Except for September 1995 and November 2002, when changepoints occurred, the results revealed the homogeneous nature of temperature and rainfall in the zone. More drought events were observed in the dry and minor seasons, while the wet season had more wetness events under both the SPEI-3 and SPEI-12 timescales. The results also showed that, while moderate-to-severe drought events were common for most years, extreme drought events were more typical in the 1980s and 1990s than in the 2000s under both the SPEI-3 and SPEI-12. Furthermore, the 2000s saw more moderate-to-severe wetness events than the 1980s and 1990s, while the greatest number of extreme wetness events occurred in 1987, followed by 1997 and 2021 under the SPEI-3, and a few moderate-to-extreme wetness events occurred in 1987, 1991, 1997–1998, 2012–2013, 2018, and 2020–2021 under the SPEI-12. Under the SPEI-12, only extreme drought events showed a significant positive trend with a small magnitude of change. On the spatial scale, drought and wetness events occurred more frequently in the Central and Volta regions than in the Greater Accra region; however, the intensity and duration of the events were stronger and lasted longer in the Greater Accra and Central regions than in the Volta region. The regular monitoring of drought and wetness events is required to protect the livelihoods of people in the zone.
... Gozzo et al. [57]; Vega et al. [58]; Drumond et al. [59]; ...
The Paraná Hydrographic Region (PHR) is one of the main hydrographic basins in Brazil, standing out for its energy generation and consumption, among other ecosystem services. Thus, it is important to identify hydrological drought events and the driest periods inside of these droughts to understand the anomalous atmospheric circulation patterns associated with them (a multiscale study). This study used the standardized precipitation index (SPI) for the 12-month scale to identify hydrological drought episodes in the PHR from 1979 to 2021. For these episodes, the severity, duration, intensity, and peak were obtained, and the SPI-6 was applied to the longest and most severe drought to identify periods with dry conditions during the wet season. Anomalous atmospheric and oceanic patterns associated with such episodes were also analyzed. The results reveal that the longest and most severe hydrological drought on the PHR started in 2016. The end of this episode was not identified by the end of the analyzed period. The SPI-6 revealed three rainy seasons during this drought event marked by anomalous dry conditions: 2016/2017, 2019/2020, and 2020/2021. In general, the circulation patterns identified differ in each period, for example, in 2016/2017, an El Niño event was dominant, in 2019/2020, the tropical Pacific Ocean showed neutral conditions, and in 2020/2021, a La Niña episode was registered. Despite that, in the three periods, the anomalous atmospheric patterns contributed to the weakening of the low-level jet east of the Andes and, consequently, to the decreasing of the moisture transport to the PHR, then leading to dry conditions over the basin.
... Every year the state faces significant economic losses, with a high number of people affected, including deaths, especially in the rainy season (summer) when floods and landslides occur (Nobre et al., 2011;Zilli et al., 2016). Severe droughts have also affected the state of São Paulo and has generated situations of water, food and energy insecurity Nobre et al., 2016;Coelho et al., 2016;Rodrigues et al., 2019;Gozzo et al., 2019;Getirana et al., 2021). ...
... In a study for a few Brazilian states evaluating two datasets with more than 70 years of data, Zilli et al. (2016) found an increase in the frequency of rainy days and extreme daily precipitation only in the state of São Paulo. Gozzo et al. (2019) evaluated data from 1901 to 2010 and noted an increasing frequency of dry events in the north and northeastern portions of the state during the crop-growing season (spring), a positive trend in the extreme rainy events in the southern region, as well as a decrease of rainfall amounts in the central and western portions during winter, which is the driest season. A study for the Metropolitan Area of São Paulo showed that while between 1941 and 2000 there were 10 occurrences of rainfall above 100.0 ...
The study assessed changes in rainfall variability and the frequency of extreme events (very wet and very dry) in the state of São Paulo, Brazil, for a 40-year period that divided into two sub-groups: 1973-1992 (P1) and 1993-2012 (P2). Data of 79 rain gauge stations were selected to represent the different climatic and geomorphological domains of the state. The annual pattern was evaluated through the scale and the shape parameters of the gamma distribution and the 95th and the 5th percentiles thresholds, the latter also employed to evaluate the seasonal spatial patterns (rainy season, Oct.-Mar. and sub-humid to dry season, Apr.-Sep.). Results showed that the average precipitation was similar in P1 and P2, but São Paulo evolved to a pattern of increased irregularity in the rainfall distribution, with a rise of approximately 10% in the number of extremes between 1973 and 2012, especially in the very dry occurrences, and in the north and west of the state, which are the least rainy regions. Moreover, while 55% of the evaluated rain gauges recorded more extreme wet episodes in P2, 76% registered more dry extreme episodes in the same period. Some very dry or very wet events recorded after the 40-year period evaluated were discussed in terms of the associated weather patterns and their impacts on society and attested to the validity of the results found in the quantitative assessment. The qualitative analysis indicates that if the trends of more irregular distribution of rain and increase in extreme events persist, as pointed out by the gamma and percentile analyses, they would continue to bring serious effects on the natural and social systems in the state, which is the most populous and has the strongest and most diversified economy in Brazil.
... This also overlaps with the lower yields simulated in 1998 for Recife (Northeast), but was not captured in 1993 possibly due to a mismatch of regional planting/ratooning date adopted by farmers in that year ( Figure S24). The other regions showed lower interannual yield variability, except for the beginning of the 1980s which was also marked by a period of strong droughts in Southeast Brazil (Gozzo et al., 2019). ...
Bioenergy from sugarcane production is considered a key mitigation strategy for global warming. Improving its representation in land surface models is important to further understand the interactions between climate and bioenergy production, supporting accurate climate projections and decision‐making. This study aimed to calibrate and evaluate the Joint UK Land Environment Simulator (JULES) for climate impact assessments in sugarcane. A dataset composed of soil moisture, water and carbon fluxes and biomass measurements from field experiments across Brazil was used to calibrate and evaluate JULES‐crop and JULES‐BE parametrisations. The ability to predict the spatiotemporal variability of sugarcane yields and the impact of climate change was also tested at five Brazilian microregions. Parameters related to sugarcane allometry, crop growth and development were derived and tested for JULES‐crop and JULES‐BE, together with the response to atmospheric carbon dioxide, temperature and drought (CTW‐response). Both parametrisations showed comparable performance to other sugarcane dynamic models, with an RMSE of 6.75 and 6.05 t ha‐1 for stalk dry matter for JULES‐crop and JULES‐BE, respectively. The parametrisations were also able to replicate the average yield patterns observed in the five microregions over 30 years when the yield gap factors were taken into account, with the correlation (r) between simulated and observed interannual variability of yields ranging from 0.33 to 0.56. An overall small positive trend was found in future yield projections of sugarcane using the new calibrations, with exception of the Jataí mesoregion which showed a clear negative trend for the SSP5 scenario from the year 2070 to 2100. Our simulations showed that an abrupt negative impact on sugarcane yields is expected if daytime temperatures above 35 oC become more frequent. The newly calibrated version of JULES can be applied regionally and globally to help understand the interactions between climate and bioenergy production.
... SPI was calculated from the areal average of mean monthly precipitation to represent droughts in a broad area, avoiding localized precipitation anomalies resulting from smaller scale processes. Correlation between SPI obtained from areal average and from weather stations is moderate to high, as shown by Gozzo et al. (2019), indicating that SPI areal average may be a good representation of the drought conditions over diverse locations in SP. ...
Dry conditions occurred over São Paulo state (southeastern Brazil) from February to July 2018, causing the driest semester in 35 years. Socioeconomic impacts included a record number of fire spots, most adverse conditions to pollutant dispersion in 3 years and the winter's lowest water reservoirs stored volume in 17 years. This paper discusses climate drivers to the onset and persistence of the dry conditions, with special attention to the intraseasonal forcing. Barotropic atmospheric circulations forced by the intraseasonal Pacific-South America teleconnection pattern, embedded in the lower frequency setup of the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation, were identified as main large-scale forcings to reduce precipitation. Drought evolution was modulated by other intraseasonal drivers such as the Madden Julian, Antarctic and 10–30 days Oscillations. A break in the 6-month dry condition, in March 2018, highlighted the important role of such oscillations in determining precipitation anomalies over SP. Results show that intraseasonal phenomena and their interactions control drought characteristics such as magnitude, persistence and spatial distribution within a setup determined by lower-frequency oscillations. The intraseasonal timescale seems to be key and must be considered for a complete description and understanding of the complex drought evolution process in São Paulo.
