Celina Cândida Ferreira Rodrigues

The Southern Ocean (SO) plays a fundamental role in the planet’s climate system, due to its ability to absorb and redistribute heat and CO₂ (an important greenhouse gas). In addition, the SO connects three large oceanic basins the Pacific, the Atlantic, and the Indian Oceans, and it has an important role in the nutrient distribution in these oceans. However, the SO is poorly sampled, with most measurements made in austral spring and summer. The variability in the air–sea CO₂ flux is estimated, as well as the role of atmospheric and oceanic variables in this variability. The CO₂ fluxes are calculated using the bulk parameterization method, in the Atlantic sector of the Southern Ocean, from 2003 to 2022, using in situ measurements, satellites, and a reanalysis data set. A neural network model is built to produce maps of the partial pressure of CO₂ in seawater (pCO_2sea). The CO₂ flux varies from −0.05 to 0.05 gC m⁻² month⁻¹. The Atlantic sector of the SO is a sink of CO₂ in summer and spring and becomes a source in austral winter and autumn. The CO₂ absorption intensifies from 2003 to 2022 by 7.6 mmol m⁻² month⁻¹, due to stronger westerly winds, related to the trend in the positive phase of the Antarctic Oscillation and the extreme El Niño Southern Ocean (ENSO) events (e.g., El Niño and La Niña).

Seasonally dry tropical forests, like the Caatinga, exhibit natural precipitation seasonality, influencing water sources for woody vegetation. This study assessed how seasonality affects the water dynamics of five deciduous plant species in the Caatinga using isotopic analyses (δ ² H and δ ¹⁸ O) of xylem water, soil, and precipitation across wet, intermediate, and dry periods. During the wet season, plant isotopic signals were more enriched than those of soil, with overlapping dual-space isotopic lines. Despite differences between plant and local meteoric water lines (LMWL), δ ² H mean values showed no significant variation, indicating partial reliance on rainwater and soil. In the dry season, isotopic signals remained enriched, but plant and soil isotopic lines diverged, reflecting shifts in water sources. Some individuals accessed shallow soil water layers, evidenced by comparable δ ¹⁸ O mean values. The study revealed significant variability in water source dynamics across seasons, with vegetation primarily relying on shallow soil water and precipitation during wet periods. However, the exact water sources accessed remain inconclusive due to methodological limitations. These findings underscore the complexity of water dynamics in the Caatinga and emphasize the need for refined methodologies to improve understanding of vegetation water-use strategies. This knowledge is crucial for informing conservation strategies in this unique biome, particularly as it faces increasing pressure from climate change and human activities.

The Southern Ocean (SO) plays a fundamental role in the planet’s climate system, due to its ability to absorb and redistribute heat and CO2 (an important greenhouse gas). Besides, the SO interconnects three large oceanic basins the Pacific, the Atlantic, and the Indian Oceans, and it has an important role in the nutrient distribution into these oceans. However, the SO is poorly sampled with most measurements made in austral spring and summer. The variability of the air-sea CO2 flux is estimated, as well as the role of atmospheric and oceanic variables in this variability. The CO2 fluxes are calculated by the bulk parameterization method, in the Atlantic sector of the Southern Ocean, from 2003 to 2022, using in situ measurements, satellites and reanalysis data set. A neural network model is built to produce maps of the partial pressure of CO2 in seawater (pCO2sea). The CO2 flux varies from -0.05 to 0.05 gC m-² month-1. The Atlantic sector of the SO is a sink of CO2 in summer and spring and becomes a source in austral winter and autumn. The CO2 absorption intensifies from 2003 to 2022 by 7.6 mmol m-²month-1, due stronger westerly winds, related to the trend of the positive phase of the Antarctic Oscillation and the extreme events of El Niño and La Niña.

The oceans play an important role in mitigating climate change by acting as large carbon sinks, especially at high latitude regions. The Southern Ocean plays a major role in the global carbon dioxide (CO₂) budget. This work aims to investigate the behavior of turbulent CO₂ fluxes and quantify it under different atmospheric and oceanic conditions in the Drake Passage and Bransfield Strait regions on high spatiotemporal resolutions when compared with traditional CO₂ fluxes estimations. The atmospheric stability condition was used to corroborate the description of CO₂ fluxes. In situ, satellite, and reanalysis data from 08 to 22 November 2018, were used in this work. The Bransfield Strait uptaked 38.59% more CO₂ than the Drake Passage due to the cold and fresh waters, allied to the influence of glacial meltwater dilution. Which increased the CO₂ solubility, directing the CO₂ fluxes to the ocean. The Bransfield Strait had predominantly stable atmospheric conditions, which contributed to this region acting as a CO₂ sink. The Drake Passage, on average, behaved as a CO₂ sink, mainly due to physical characteristics. This research contributes to a better understanding of the Southern Ocean’s role in the global carbon balance on scales that are very difficult to monitor.

The Antarctic region has experienced recent climate and environmental variations due to climate change, such as ice sheets and ice shelves loss, and changes in the production, extension, and thickness of sea-ice. These processes mainly affect the freshwater supply to the Southern Ocean and its water masses formation and export, being crucial to changes in the global climate. Here, we review the influence of the glacial freshwater input on the Antarctic Peninsula adjacent ocean. We highlight each climate process' relevance on freshwater contribution to the sea and present a current overview of how these processes are being addressed and studied. The increase of freshwater input into the ocean carries several implications on climate, regionally and globally. Due to glacier melting, the intrusion of colder and lighter water into the ocean increases the stratification of the water column, influencing the sea-ice increase and reducing ocean-atmosphere exchanges, affecting the global water cycle. This study shows the role of each hydrological cycle processes and their contributions to the regional oceanography and potentially to climate.

The ESECAFLOR Project artificially induces a prolonged drought period and studies the consequences on the flows of water and carbon dioxide in an Amazon Rainforest, assessing the impacts on the ecosystem in response to this exclusion of water in the soil, a fact similar to the influence of a event of El Niño. ESECAFLOR is located in the National Forest of Caxiuanã, in the municipality of Melgaço. The objective of this work is to study soil temperature and soil moisture variability in the Brazilian Amazon. The data used refer to a period of 3 years. The results indicated greater soil moisture variability in the control plot (A), when compared to the exclusion plot (B), due to the latter having water stress. In plot B, the soil moisture remained practically constant during the studied period. In relation to the soil temperature, the variations were small in both plots, but with higher values in plot B in relation to plot A, since much of the energy that reaches the surface is used as sensible heat for its heating. With the exclusion of water in the forest soil, the life cycle may suffer irreversible changes.

This work aims to establish a relationship between the photosynthetically active radiation (PAR) and the global radiation (Rg) for Santa Rita do Passa Quatro (SP), during the period from February 2005 to February 2006 and evaluate its impact on gross primary production (GPP). Data of Rg (Wm-2) and PAR (μmols s-1m-2) were obtained from the mirometeorological tower located in Gleba Cerrado Giant Foot. Data analysis allowed the establishment of a linear equation to express the relationship between PAR (MJ m-2) and Rg (MJ m-2) as: PAR = 0.3787 Rg or PAR = 1.742 Rg, for PAR (μmols s-1m-2) and Rg (MJ m-2). This relationship is indicated for the GPP determination when there is no PAR measurements.

A radiação atmosférica de ondas prolongadas tem uma importância considerável nos estudos meteorológicos, bem como no aquecimento global. Por estar ligado aos gases atmosféricos e à temperatura do ar. Este artigo tem como objetivo avaliar o desempenho de doze modelos para a estimativa da radiação de onda longa atmosférica em Brasília-DF. Os dados meteorológicos utilizados neste estudo foram adquiridos a partir da rede de dados do Sistema de Organização de Dados Ambientais - SONDA. Neste estudo, os dados da temperatura do ar, umidade relativa, radiação global e radiação atmosférica de onda longa foram utilizados para os modelos avaliados. Os cálculos foram processados com médias horárias e diárias. A avaliação dos modelos e a comparação dos resultados estimados e medidos da radiação da onda longa atmosférica foram realizadas utilizando os métodos estatísticos do erro médio quadrado (RMSE), erro absoluto médio (MAE) e erro médio médio relativo (PMRE). O coeficiente de correlação de Pearson (r) e o coeficiente de determinação (R²) também foram aplicados. Os modelos que tiveram excelentes resultados foram Brunt (1932), Prata (1996), Berdahl e Martin (1984), Idso (1982) e Berger et al. (1984), uma vez que apresentaram um bom desempenho, devido aos menores valores de RMSE , MAE e PMRE