Distribution of Articles published per year
(2000 - 2018)
(2000 - 2018)
Total number of journals
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Article 0 Reads 0 Citations Increased Amazon freshwater discharge during late Heinrich Stadial 1 Published: 01 February 2018
Quaternary Science Reviews, doi: 10.1016/j.quascirev.2017.12.005
Article 0 Reads 0 Citations Characterizing the exceptional 2014 drought event in São Paulo by drought period length Published: 30 September 2017
Climate Dynamics, doi: 10.1007/s00382-017-3932-2
In the last decade, the southeast region of Brazil has been suffering severe water shortages. Here, we propose to compute the expected drought period length to characterize the drought events in the region of São Paulo. We report the unique properties of the exceptional drought event during the austral summer 2014 by showing the differences and similarities to the very dry season in 2001 and the mild dry seasons in 2006 and 2015. Furthermore, we investigate the correlations of the abnormal precipitation deficit with the ocean and atmospheric patterns. In comparison to other drought events, we validate the hypothetical mechanism that underlies the exceptional drought 2014: (1) The existence of an anomalous high pressure center in the area acts as a blocking mechanism that prevents moisture transport from the Amazon and passage of cold front systems from south Brazil. This blocking high has been observed in all dry seasons considered, with much larger magnitude in 2014. (2) The much faster increasing trend of the anomalous sea surface temperature acts as a strong feedback which intensified the extreme climate conditions. The unprecedented increasing trend of the SST in 2014 was not observed in other climate variables representing a high pressure center. Therefore, we conclude that the exceptional drought 2014 was enhanced by the feedback mechanism of anomalous warming of SST in the South Atlantic Oceans, which was resulted from the anomalous high pressure.
Article 0 Reads 1 Citation Effects of the surface heterogeneities on the local climate of a fragmented landscape in Amazonia using a tile approach ... Published: 01 April 2017
Quarterly Journal of the Royal Meteorological Society, doi: 10.1002/qj.3026
This study evaluates the use of tiles to estimate the effects of surface heterogeneities in simulations of local climate in a landscape-fragmented region of the Amazonia. Three experiments using the Eta/Noah-MP model were designed as follows: two experiments with a spatial resolution of 5 km with and without the use of the tile approach. The third experiment used a finer spatial resolution of 2 km without the use of the tile approach (high-resolution experiment). Simulations were carried out for the rainy and dry seasons, which correspond to the months of March and September 2003, respectively. In general, the magnitude of surface fluxes is significantly affected by the introduction of tiles. In the dry season, the use of tiles in the simulation increases the magnitude of precipitation (about 7 mm day−1), skin temperature (about 4 °C), sensible heat flux (about 80 W m−2) and surface albedo (about 0.7). It reduces the latent heat flux (about 30 W m−2) and net radiation (about 40 W m−2). On the other hand, in the rainy season, the model produces excessive precipitation. This may have partly masked the signs of the land fragmentation impact. The tile experiment generates a warmer and drier boundary layer during the dry season. The impact of the surface heterogeneity representation is higher in the dry season than in the rainy season. The results suggest that the degree of impact of the subgrid process representation on the local climate is related to the spatial scale of the fragmentation. The use of the tile approach improves the representation of the effects of landscape heterogeneity on the spatial distribution of surface fluxes variability in fragmented areas. Comparison against measured data from flux towers in the region show that the model can simulate diurnal and seasonal variations in the local fluxes, despite the biases.
Article 0 Reads 13 Citations Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks Published: 13 March 2017
Nature Communications, doi: 10.1038/ncomms14681
Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation-atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. We apply a novel complex-network approach, in which Amazon forest patches are linked by observation-based atmospheric water fluxes. Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. Under dry-season Amazonian rainfall reductions, comparable to Last Glacial Maximum conditions, additional forest loss due to self-amplified effects occurs in 10-13% of the Amazon basin. Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest.
Article 0 Reads 4 Citations A seca e a crise hídrica de 2014-2015 em São Paulo Published: 02 September 2015
Revista USP, doi: 10.11606/issn.2316-9036.v0i106p31-44
Resumo A maior parte da estação chuvosa de 2014 transcorreu com valores de chuva inferiores à média histórica sobre a porção sudeste do país, incluindo o Sistema Cantareira. A causa principal para a grande falta de chuva foi a atuação de um intenso, persistente e anômalo sistema de alta pressão atmosférica que prejudicou o transporte de umidade da Amazônia, assim como a passagem/ desenvolvimento dos principais sistemas causadores de chuva, como a Zona de Convergência do Atlântico Sul e as frentes frias. Esse sistema, denominado de bloqueio atmosférico, teve uma duração de 45 dias, fato que resulta extremamente raro. A combinação dos baixos índices pluviométricos, o grande crescimento da demanda de água e o ineficiente gerenciamento desse recurso têm gerado uma “crise hídrica” durante os anos 2014 e 2015
Article 0 Reads 3 Citations Comparisons of the Noah-MP land surface model simulations with measurements of forest and crop sites in Amazonia Published: 28 August 2015
Meteorology and Atmospheric Physics, doi: 10.1007/s00703-015-0399-8