Search Results (2)

The El Niño-Southern Oscillation (ENSO) stands out as the most significant tropical phenomenon in terms of climatic magnitude resulting from ocean–atmosphere interaction. Due to its atmospheric teleconnection mechanism, ENSO influences various environmental variables across distinct atmospheric scales, potentially impacting the spatiotemporal distribution of atmospheric aerosols. Within this context, this study aims to evaluate the relationship between ENSO and atmospheric aerosols across the entire Legal Amazon during the period from 2006 to 2011. Over this five-year span, four ENSO events were identified. Concurrently, an analysis of the spatiotemporal variability of aerosol optical depth (AOD) and Black Carbon radiation extinction (EAOD-BC) was conducted alongside these ENSO events, utilizing data derived from the Aerosol Robotic Network (AERONET), MERRA-2 model, and ERSSTV5. Employing the Windowed Cross-Correlation (WCC) approach, statistically significant phase lags of up to 4 to 6 months between ENSO indicators and atmospheric aerosols were observed. There was an approximate 100% increase in AOD immediately after El Niño periods, particularly during intervals encompassing the La Niña phase. The analysis of specific humidity anomaly (QA) revealed that, contrary to expectations, positive values were observed throughout most of the El Niño period. This result suggests that while there is a suppression of precipitation events during El Niño due to the subsidence of drier air masses in the Amazon, the region still exhibits positive specific humidity (Q) conditions. The interaction between aerosols and humidity is intricate. However, Q can exert influence over the microphysical and optical properties of aerosols, in addition to affecting their chemical composition and aerosol load. This influence primarily occurs through water absorption, leading to substantial alterations in radiation scattering characteristics, and thus affecting the extinction of solar radiation. Full article

The Pantanal is the largest wetland of the world and one of the most important biodiversity hotspots in South America. An unprecedented ongoing megadrought is severely affecting its ecological functioning, flood pulse dynamics, and fire regime. Regarding this problematic, the present study generates reliable information about the following key issues: 1—Evolution and dynamics, 2—Origin and determinants, and 3—Forecast based on identified determinants and current trends. Results show that the evolution of the megadrought has been differentiable in both, space and time. As for its origin and determinants, Climate Change was ratified as one of the most important threats to the Pantanal, and to vast areas of South America, since a strong correlation was identified between megadrought’s dynamics and the occurrence of intense marine heatwaves at Northern Hemisphere oceanic waters, and more specifically, at the Northeast Pacific. Results also show that the megadrought is expected to continue at both the Pantanal and the surrounding Highlands, at least until December 2023. Thus, an intensification of fires risk, extending now to areas historically flooded or perhumid should be expected, concomitantly to a very negative impact on non-fire-resistant vegetation cover, as well as ecosystem functioning and biodiversity, perhaps even worse than those from 2020, widely covered by the international media. Full article