Drought-related disasters are among the natural disasters that are able to cause large economic and social losses. In recent years, droughts have affected different regions of Brazil, impacting water, food, and energy security. In this study, we used the Integrated Drought Index (IDI), which combines a meteorological-based drought index and remote sensing-based index, to assess the drought events from 2011 to 2019 over Brazil. During this period, drought events were observed throughout the country, being most severe and widespread between the years 2011 and 2017. In most of the country, the 2014/15 hydrological year stands out due to the higher occurrence of severe and moderate droughts. However, drought intensity and observed impacts were different for each region, which is shown by the different case studies, assessing different types of impacts caused by drought in Brazil. Thus, it is fundamental to evaluate the impacts of droughts in a continental country such as Brazil, where a variety of vegetation, soil, land use, and especially different climate regimes predominate.

CHUVA, meaning “rain” in Portuguese, is the acronym for the Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (GPM). The CHUVA project has conducted five field campaigns; the sixth and last campaign will be held in Manaus in 2014. The primary scientific objective of CHUVA is to contribute to the understanding of cloud processes, which represent one of the least understood components of the weather and climate system. The five CHUVA campaigns were designed to investigate specific tropical weather regimes. The first two experiments, in Alcantara and Fortaleza in northeastern Brazil, focused on warm clouds. The third campaign, which was conducted in Belém, was dedicated to tropical squall lines that often form along the sea-breeze front. The fourth campaign was in the Vale do Paraiba of southeastern Brazil, which is a region with intense lightning activity. In addition to contributing to the understanding of cloud process evolution from storms to thunderstorms, this fourth campaign also provided a high-fidelity total lightning proxy dataset for the NOAA Geostationary Operational Environmental Satellite (GOES)-R program. The fifth campaign was carried out in Santa Maria, in southern Brazil, a region of intense hailstorms associated with frequent mesoscale convective complexes. This campaign employed a multimodel high-resolution ensemble experiment. The data collected from contrasting precipitation regimes in tropical continental regions allow the various cloud processes in diverse environments to be compared. Some examples of these previous experiments are presented to illustrate the variability of convection across the tropics.

The intraseasonal variability of the South Atlantic Convergence Zone is investigated applying statistical techniques to the daily NCEP/NCAR reanalysis data set and the daily-interpolated NOAA satellites OLR, both ranging from 1979 to 1999. The data were filtered to retain frequency fluctuations between 30 and 90 days. The intrinsic connection among tropical convection in the Indonesian region, the subtropical flow and the convection in the South Atlantic Convergence Zone (SACZ) is discussed. The analyses are consistent with previous suggestions of the influence of Madden-Julian Oscillation (MJO) on tropical South American convection and studies of the Pacific South American (PSA) wavetrain role on SACZ. In the present study, the two dominant intraseasonal modes of variability affecting the SACZ are discussed on the basis of a zonal mode (the Madden-Julian Oscillation) and a tropical-extratropical mode (Pacific South American Pattern). The opposite convective behaviour between Indonesia and tropical South America is discussed, as well as the connection between SACZ convection and PSA-like pattern. It was noticed that an SACZ episode occurring in the northernmost position can be influenced by the MJO, and can trigger a wavetrain over the South Atlantic and Indian Ocean, while positions further south can be influenced by a tropical-extratropical PSA-like wavetrain. High-frequency (2-10 days) analysis displayed dominant wavetrain patterns of shorter wavelength than the intraseasonal wavetrain, but with similar characteristics, over South America, indicating the influence of synoptic systems, like frontal zones, over the continent. It is suggested that when these two frequencies, high (frontal systems) and intraseasonal (MJO or PSA), are in phase, they are able to establish appropriate conditions for an SACZ episode development.

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Brazil has endured the worst droughts in recorded history over the last decade, resulting in severe socioeconomic and environmental impacts. The country is heavily reliant on water resources, with 77.7% of water consumed for agriculture (irrigation and livestock), 9.7% for the industry, and 11.4% for human supply. Hydropower plants generate about 64% of all electricity consumed. The aim of this study was to improve the current state of knowledge regarding hydrological drought patterns in Brazil, hydrometeorological factors, and their effects on the country’s hydroelectric power plants. The results show that since the drought occurred in 2014/2015 over the Southeast region of Brazil, several basins were sharply impacted and remain in a critical condition until now. Following that event, other regions have experienced droughts, with critical rainfall deficit and high temperatures, causing a pronounced impact on water availability in many of the studied basins. Most of the hydropower plants end the 2020–2021 rainy season by operating at a fraction of their total capacity, and thus the country’s hydropower generation was under critical regime.