ABSTRACT
Studies and observations have pointed out that recent wildfires have been more severe and burned area is increasing in tropical regions. The current study aims at investigating the influence of oceanic climate modes and their teleconnection on global fire danger and trends in the 1980-2020 interval. Disentangling these trends demonstrates that across the extratropics they are primarily related to increases in temperature, whereas in the tropics changes in short-term precipitation distribution dominates the trends. Moreover, the environmental impact of short-term precipitation is dependent on local vegetation type and tightly related to oceanic temperatures far from the burned areas. Indeed, in the 2001-2020 period, a warmer tropical North Atlantic was associated with more fires in the Amazon and Africa, whereas ENSO has weakened the fire activity in equatorial Africa. The remarkable impact of oceanic modes of climate variability in inducing environmental conditions conducive to fires, has particular relevance for the seasonal spatiotemporal wildfire forecasts. Although local aspects are crucial for fire management, long-term predictions should take into account the behavior of potential climate drivers located far from the region of interest. Such teleconnections can be identified ahead of local weather anomalies.
ABSTRACT
Sea surface temperature (SST) anomalies caused by a warm core eddy (WCE) in the Southwestern Atlantic Ocean (SWA) rendered a crucial influence on modifying the marine atmospheric boundary layer (MABL). During the first cruise to support the Antarctic Modeling and Observation System (ATMOS) project, a WCE that was shed from the Brazil Current was sampled. Apart from traditional meteorological measurements, we used the Eddy Covariance method to directly measure the ocean-atmosphere sensible heat, latent heat, momentum, and carbon dioxide (CO2) fluxes. The mechanisms of pressure adjustment and vertical mixing that can make the MABL unstable were both identified. The WCE also acted to increase the surface winds and heat fluxes from the ocean to the atmosphere. Oceanic regions at middle and high latitudes are expected to absorb atmospheric CO2, and are thereby considered as sinks, due to their cold waters. Instead, the presence of this WCE in midlatitudes, surrounded by predominantly cold waters, caused the ocean to locally act as a CO2 source. The contribution to the atmosphere was estimated as 0.3 ± 0.04 mmol m-2 day-1, averaged over the sampling period. The CO2 transfer velocity coefficient (K) was determined using a quadratic fit and showed an adequate representation of ocean-atmosphere fluxes. The ocean-atmosphere CO2, momentum, and heat fluxes were each closely correlated with the SST. The increase of SST inside the WCE clearly resulted in larger magnitudes of all of the ocean-atmosphere fluxes studied here. This study adds to our understanding of how oceanic mesoscale structures, such as this WCE, affect the overlying atmosphere.
ABSTRACT
Extreme climatic events and their hazards have strong impact on society. Urban areas in Brazil are especially vulnerable to the impact of such events due to their rapid growth and inappropriate infrastructure. Viçosa is a mid-sized city in Southeastern Brazil that has been experiencing issues associated with urban expansion and population growth since the 1960s. Thus, this study aims to identify patterns of extreme climate events in Viçosa based on daily temperature and precipitation time series (1968-2017). Homogeneity tests were carried out in order to identify breaking points in these climate variables. Climate trends were analyzed through Mann-Kendall test and their magnitude was checked based on Sen's slope. Results have evidenced statistically significant and increasing trends in annual minimum temperature since the 1990s. Moreover, statistically significant breaking points in extreme temperature indices have shown increasing number of warm days, and decreasing number of cold nights, in both annual and seasonal analyses. Extreme climatic events have been observed more often in recent years, mainly in the number of consecutive dry days and maximum and heavy precipitation days. Based on results, Viçosa experiences warmer conditions throughout the year, whereas more (less) torrential rainfall events have been occurring during Summer (Winter).
Subject(s)
Temperature , Brazil , Cities , SeasonsABSTRACT
The semi-arid region of Northeast Brazil (NEB) experiences severe droughts during El Niño Southern Oscillation (ENSO) years, with major impacts on the dynamics of the native vegetation (Caatinga). However, the effect of these droughts on carbon cycling is not well understood. Here, a numerical model is used to investigate the influence of variations in Pacific and Atlantic sea surface temperatures (SST) on drought and carbon dynamics of the Caatinga during past ENSO events. We demonstrate that precipitation reductions in the Caatinga have a strong influence on vegetation dynamics, with net primary production (NPP) remaining low throughout the droughts. Furthermore, the Caatinga acts as a carbon sink, even in years of severe drought. However, net ecosystem exchange (NEE) is lower in years of low NPP rates, resulting in long periods with limited ecosystem activity. The SST patterns indicate that extreme vegetation changes in the Caatinga are associated with the combination of ENSO events and North Atlantic SST warming.
Subject(s)
El Nino-Southern Oscillation , Forests , Brazil , Pacific OceanABSTRACT
Understanding the impact of Asian soybean rust on soybean yield is of great importance in the crop simulation model for this crop become it is possible to predict yield using different sowing dates and growth conditions. The goal of this study were to evaluate the performance of two soybean cultivars in Triângulo Mineiro/Alto Paranaíba, MG, Brazil and the effects of soybean rust on the yield of these cultivars using the CSM-CROPGRO Soybean model. Two soybean cultivars "NK 7074" (early) and "UFUS-Impacta" (medium late), which differ in their development cycles, were growing in Uberaba city during the 2009/2010 growing season. The validation for cultivar "UFUS-Impacta" was conducted comparing the measured and simulated yield data considering three different sowing dates in the "Uberlândia" city during the 2002/2003 growing season. Daily meteorological data obtained from six meteorological stations of the National Institute of Meteorology (INMET). To determine the performance of the soybean cultivars and the effect of soybean rust on yield, three different scenarios were used: no occurrence of rust (NOR) and occurrence of rust with inoculum concentrations of U5.000 and U10.000 urediniospores/mL. For all environments studied, the early cultivar had the best performance than the medium late cultivar. Soybean rust had the most effect on yield for the U10.000 scenario than for the U5.000 scenario. The best soybean performance occurred for "Araxá" and "Uberaba" cities. The SouthSoutheast area of the "Triângulo Mineiro/Alto Paranaíba" region was the most sensitive to the effect of rust on yield compared to the North region.
Compreender o impacto da ferrugem asiática na produtividade da soja é de grande importância para os modelos de simulação dessa cultura, pois pode-se prever a produtividade utilizando-se diferentes datas de semeadura e condições de crescimento. O objetivo deste estudo foi analisar a performance de duas cultivares de soja na região do Triângulo Mineiro/Alto Paranaíba, MG, Brasil e os efeitos da ferrugem asiática da soja na produtividade desses cultivares utilizando o modelo CSM-CROPGRO Soybean. Duas cultivares de soja NK 7074 (precoce) e UFUS-Impacta (semitardia), as quais diferem nos seus ciclos de desenvolvimento, foram cultivadas em Uberaba na safra 2009/2010. A validação para a cultivar UFUS-Impacta foi conduzida comparando os dados observados e simulados de produtividade considerando três diferentes datas de semeadura na safra 2002/2003 em Uberlândia, MG. Foram utilizados dados meteorológicos diários de seis estações meteorológicas do Instituto Nacional de Meteorologia (INMET). Para determinar o desempenho das cultivares de soja e o efeito da ferrugem na produtividade, utilizou-se três diferentes cenários denominados de: não ocorrência de ferrugem (NOR) e ocorrência de ferrugem nas concentrações de inóculo de U5.000 e U10.000 urediniósporos/mL. Para todos os ambientes estudados, a cultivar precoce teve o melhor desempenho em relação a cultivar semi-tardia. A ferrugem da soja teve maior impacto na produção para o cenário U10.000 do que para o cenário U5.000. O melhor desempenho das cultivares de soja foram para as cidades de Araxá e Uberaba. A área Sul-Sudeste do Triângulo Mineiro/Alto Paranaíba foi a mais sensível ao efeito da ferrugem na produtividade em comparação com a região norte.
Subject(s)
Glycine max , Crop Production , Efficiency , Phakopsora pachyrhiziABSTRACT
Agreement on the criteria for granting the right to use water resources between governing bodies represents a significant advance in the process of sharing water use. To aid water resource management agencies in optimizing water use, the impact of using different criteria for permitting water use in the Paracatu river basin, Brazil, was evaluated in this study. The streamflow criteria corresponding to 30 % of the annual Q(7,10) (used by the governing body of Minas Gerais), 70 % of the annual Q(95) (used by the governing body of the union), 30 % of the monthly Q(7,10), and 70 % of the monthly Q(95) were evaluated. The use of criteria based on the monthly streamflow allows for better management of water use because it allows for greater utilization of this resource in times when there is high water availability and imposes a more realistic restriction during critical periods. Substitution of the annual Q(7,10) for the monthly Q(7,10) significantly increases the streamflow permitted in some months, for example, from December to May. Use of the criterion of 70 % of the annual Q(95) involves a high risk of drought in critical months, while the criterion of 70 % of the monthly Q(95) minimizes this risk.
