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No dia 19 de agosto de 2019, a cidade de São Paulo (SP) presenciou um evento incomum que deixou grande parte da população assustada com o ocorrido. Próximo às 15 h, o céu na cidade de São Paulo escureceu tornando o dia em noite. Diante desse contexto, o objetivo do estudo é descrever o ambiente atmosférico associado ao evento registrado em São Paulo. Para tanto, foram utilizadas diferentes fontes de dados: cartas sinóticas e análises de modelos de tempo do Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), imagens de satélite, dados de diferentes modelos atmosféricos, monitoramento da qualidade do ar Companhia Ambiental do Estado de São Paulo (CETESB) e notícias veiculadas pela mídia. Nos dias prévios ao 19 de agosto foram documentadas queimadas na Amazônia e a presença de ventos em baixos níveis da atmosfera (~700 hPa) que auxiliavam o transporte do material particulado das regiões de queimadas para o sul do país. No dia 19, com a chegada de um sistema frontal em São Paulo, os ventos em baixos níveis passaram a escoar da Amazônia em direção ao sudeste, transportando o material particulado para tal região. O material particulado (pluma de fumaça) não foi registrado em superfície, já que as estações da CETESB não documentaram padrão anômalo nas observações. Sugere-se que o material particulado serviu como núcleo de condensação de nuvem, gerando muitas gotículas de nuvem que refletiram radiação para fora da atmosfera, deixando escura a tarde de São Paulo.

Optical data is broadly used for change detection studies, despite being hindered by atmospheric conditions. Synthetic Aperture Radar (SAR) data can be useful for change detection in areas with frequent cloud coverage as SAR systems are capable of obtaining images almost independently from atmospheric conditions. This study aims to verify the difference in results of using SAR data instead of optical data for change detection purposes. Different levels of one hierarchical legend and both pixel and region-based classifiers were used. Change results were evaluated considering the use of rectangular matrices to incorporate the occurrence of impossible changes and relative comparison between change maps. Although the change maps obtained using only optical data were more accurate than those using either one or two land cover classifications based on L-band SAR data, the difference in the accuracy of change maps decreases with the use of less detailed legends. Additionally, results indicate that L-band SAR and multi-sensor approaches are adequate for deforestation identification even if postclassification results did not achieve global accuracy values superior to 0.86. The most accurate change detection results obtained in this work were not associated with the overall accuracy of land cover classifications, but with the distribution and accuracy of specific land cover classes.

Our paper reviews recent progress in the study and understanding of observed trends in extreme rainfall events in the Metropolitan Area of São Paulo (MASP). These are discussed in relation to hydrometeorological hazards that trigger natural disasters, such as flash floods, landslides, and droughts, that affect the population and local economies. A review of the most updated literature on rainfall and extremes in the MASP shows a significant increase in the total volume of rainy-season rainfall during the last seven decades. While there were practically no days with heavy rain (more than 50 mm) in the 1950s, these days have been occurring two to five times a year in the last 10 years. This, together with the inappropriate occupation of risky areas, such as slopes and banks of watercourses, leads to inundation, flooding, and landslides. Changes in extremes can be partly due to natural climate variability but can also be related to global warming and/or urbanization. There is ample evidence of an increasing risk of rainfall-related hazards in the MASP. This is particularly so for landslides in vulnerable areas. Exposure will continue to lead to risk increases. This calls for significant improvement in climate and disaster risk reduction and management efforts in the MASP region.

As chuvas influenciam a dinâmica hidrológica nos rios amazônicos (enchente, cheia, vazante e seca). A dinâmica hidrológica influencia os organismos aquáticos e na infraestrutura logística, econômica e social das populações que habitam as margens dos rios amazônicos. Assim, estudos que investiguem a relação da precipitação pluvial com o nível fluviométrico são necessários para entendermos essa dinâmica e melhorarmos as previsões dos modelos regionais de chuva-vazão. Para este estudo foram utilizados dados mensais de precipitação pluvial (PRP), número de dias com chuva (NDC) e nível do Rio Tapajós das estações fluviais e pluviais localizadas na cidade de Santarém-PA, os dados foram obtidos junto a Agência Nacional de Águas, para o período de janeiro de 1980 até dezembro de 2015. Foi calculada a correlação cruzada com os dados não normalizados, para identificar a defasagem com máxima relação entre a PRP/NDC e o nível do Rio. Em seguida, foram normalizados as médias anuais de nível, para identificar anos com o nível abaixo, dentro e acima da média e por último foram calculadas médias mensais para cada uma das 3 categorias, e aplicado o teste t-student. Entre os principais resultados encontrados pode-se destacar: I) Os diagramas de caixas (boxplot) mostram que todas as variáveis estudadas apresentam sazonalidade bem definida. O nível do Rio Tapajós apresenta período de máximos entre os meses de abril a junho, mínimos outubro a dezembro, e períodos de transição de janeiro a março e de agosto a setembro. Já a PRP e NDC apresenta pico entre janeiro a maio, estiagem de agosto a dezembro e transição em junho e julho; II) A correlação máxima entre PRP/NDC e Nível é máxima com defasagem de 3 meses, com valores superiores a 0,6 muito maior do que os 0,3 da defasagem 0. Assim, apresentou grande dependência temporal de 2 a 3 meses entre a chuva a cota. A cota máxima do Rio Tapajós sofre grande variação nos anos de eventos extremos (estiagem ou chuva acima da média), quando se afasta da média histórica até 1 m, porém, o mesmo não se verifica para a cota mínima, que permanece dentro da média histórica em anos de eventos extremos. Definiu-se o período hidrológico da região: cheia (abril a julho), vazante (julho a setembro), seca (outubro a dezembro), enchente (janeiro a março). O estudo demonstrou haver um padrão consistente e previsível de variação sazonal do nível fluviométrico do Rio, e sua relação direta com a pluviosidade. Essa previsibilidade pode ser importante ferramenta para a população, no planejamento anual das atividades econômicas de pesca e agricultura de várzea, de lazer, turismo e transporte fluvial. Pode também orientar com antecedência as intervenções necessárias do governo municipal na orla da cidade, que frequentemente sofre inundação no período de cheia, podendo minimizar os danos causados.

Inadequate land use planning is one of the main driving forces leading to the occurrence of erosion and environmental degradation. The negative impacts of poor planning influence soil physical quality and fertility, agricultural productivity, water quality and availability, biodiversity and other ecosystem services. In some areas, actual land use is not consistent with potential use. When this occurs, the area is termed as being in environmental land use conflict. Many studies have demonstrated the efficiency of the ruggedness number (RN) method for determining land use potential in watersheds. The RN method is simple and can be carried out using geographic information systems (GIS). However, the absence of potential land use or agricultural land suitability assessments is recurrent in territorial management plans or integrated water resources plans (IWRP), especially for macroscale river basins. Therefore, the aim of this preliminary study is to identify possible environmental land use conflicts at the Rio Grande Basin (BHRG), Brazil, using the Ruggedness Number. The results indicate high agricultural use potential and the predominance of appropriate or acceptable soil use at the BHRG. However, class 1, 2 and 3 environmental conflicts were identified in some Rio Grande sub-basins, suggesting greater environmental degradation risks. The findings clearly indicate that more exhaustive studies on environmental quality (soil capability, water, biodiversity) are required at the BHRG, especially in environmental land use conflict areas. We emphasize that this is an important preliminary study which may be carried out in any other macroscale hydrographic basin.

The climate change projections for the Caatinga biome this century are for an increase in temperature and reduction in rainfall, leading to aridization and plant cover dominated by Cactaceae. The objective of this study was to model the potential distribution of Epiphyllum phyllanthus (L.) Haw., a cactus that is native to the Caatinga biome, considering two possible future climate scenarios, to assess this species spatiotemporal response to these climate change, and thus to evaluate the need or not for conservation measures. For this purpose, we obtained biogeographic information on the target species from biodiversity databases, choosing nine environmental variables and applying the MaxEnt algorithm. We considered the time intervals 2041-2060 and 2061-2080, centered on 2050 and 2070, respectively, and the greenhouse gas scenarios RCP4.5 and 8.5. For all the scenarios considered, the models generated for 2050 and 2070 projected drastic contraction (greater than 80%) for the areas of potential occurrence of the species in relation to the present potential. The remaining areas were found to be concentrated in the northern portion of the biome, specifically in the northern part of the state of Ceará, which has particular characteristics.

The Amazon biome contains more than half of the remaining tropical forests of the planet and has a strong impact on aspects of meteorology such as the planetary boundary layer (PBL). In this context, the objective of this study was to conduct observational evaluations of the daily cycle of the height of the PBL during its stable (night) and convective (day) phases from data that were measured and/or estimated using instruments such as a radiosonde, sodar, ceilometer, wind profiler, lidar and microwave radiometer installed in the central Amazon during 2014 (considered a typical year) and 2015 during which an intense El NiñoSouthern Oscillation (ENSO) event predominated during the GoAmazon experiment. The results from the four intense observation periods (IOPs) show that during the day and night periods, independent of dry or rainy seasons, the ceilometer is the instrument that best describes the depth of the PBL when compared with in situ radiosonde measurements. Additionally, during the dry season in 2015, the ENSO substantially influenced the growth phase of the PBL, with a 15 % increase in the rate compared to the same period in 2014.

The climate of South America (SA) has long held an intimate connection with El Niño, historically describing anomalously warm sea-surface temperatures off the coastline of Peru. Indeed, throughout SA, precipitation and temperature exhibit a substantial, yet regionally diverse, relationship with the El NiñoSouthern Oscillation (ENSO). For example, El Niño is typically accompanied by drought 6.in the Amazon and north-eastern SA, but flooding in the tropical west coast and south-eastern SA, with marked socio-economic effects. In this Review, we synthesize the understanding of ENSO teleconnections to SA. Recent efforts have sought improved understanding of oceanatmosphere processes that govern the impact, inter-event and decadal variability, and responses to anthropogenic warming. ENSOs impacts have been found to vary markedly, affected not only by ENSO diversity, but also by modes of variability within and outside of the Pacific. However, while the understanding of ENSOSA relationships has improved, with implications for prediction and projection, uncertainty remains in regards to the robustness of the impacts, inter-basin climate interactions and interplay with greenhouse warming. A coordinated international effort is, therefore, needed to close the observational, theoretical and modelling gaps currently limiting progress, with specific efforts in extending palaeoclimate proxies further back in time, reducing systematic model errors and improving simulations of ENSO diversity and teleconnections.

El Niño years are characterized by a high sea surface temperature anomaly in the Equatorial Pacific Ocean, which leads to unusually warm and dry conditions over many fire-prone regions globally. This can lead to an increase in burned area and emissions from fire activity, and socio-economic, and environmental losses. Previous studies using satellite observations to assess the impacts of the recent 2015/16 El Niño found an increase in burned area in some regions compared to La Niña years. Here, we use the dynamic land surface model JULES to assess how conditions differed as a result of the El Niño by comparing simulations driven by observations from the year 2015/16 with mean climatological drivers of temperature, precipitation, humidity, wind, air pressure, and short and long-wave radiation. We use JULES with the interactive fire module INFERNO to assess the effects on precipitation, temperature, burned area, and the associated impacts on the carbon sink globally and for three regions: South America, Africa, and Asia. We find that the model projects a variable response in precipitation, with some areas including northern South America, southern Africa and East Asia getting drier, and most areas globally seeing an increase in temperature. As a result, higher burned area is simulated with El Niño conditions in most regions, although there are areas of both increased and decreased burned area over Africa. South America shows the largest fire response with El Niño, with a 13% increase in burned area and emitted carbon, corresponding with the largest decrease in carbon uptake. Within South America, peak fire occurs from August to October across central-southern Brazil, and temperature is shown to be the main driver of the El Niño-induced increase in burned area during this period. Combined, our results indicate that although 2015/16 was not a peak year for global total burned area or fire emissions, the El Niño led to an overall increase of 4% in burned area and 5% in emissions compared to a No El Niño scenario for 2015/16, and contributed to a 4% reduction in the terrestrial carbon sink.

Sigmodontine rodents are extremely diversified in the Neotropics but their fossil record remains generally poorly known, especially in Brazil. Here, we examine the assemblage of sigmodontines from the limestone cave Nossa Senhora Aparecida (21°5ʹ27.89S 56°34ʹ28.77W), located in Serra da Bodoquena (Mato Grosso do Sul), a karstic region in southwestern Brazil. We describe cranial and dental fragments and recognise the presence of some new species not previously recorded for the region, as Bibimys sp., Graomys cf. G. chacoensis, Thalpomys lasiotis, and Pseudoryzomys simplex. This fossil assemblage is comparable to others fossil sites in Brazil, such as those from Goiás and Rio Grande do Sul, with the predominance of species from open areas, including grasslands, and some of forested environments from Cerrado landscapes.