scholarly journals Regional Impacts of Future Land-Cover Changes on the Amazon Basin Wet-Season Climate

2008 ◽  
Vol 21 (6) ◽  
pp. 1153-1170 ◽  
Author(s):  
Renato Ramos da Silva ◽  
David Werth ◽  
Roni Avissar
Keyword(s):  
Land Cover ◽  
El Niño ◽  
Amazon Basin ◽  
El Nino ◽  
Atmospheric Modeling ◽  
Wet Season ◽  
Regional Impacts ◽  
A Minor ◽  
Precipitation Changes ◽  
Regional Atmospheric Modeling

Abstract State-of-the-art socioeconomic scenarios of land-cover change in the Amazon basin for the years 2030 and 2050 are used together with the Regional Atmospheric Modeling System (RAMS) to simulate the hydrometeorological changes caused by deforestation in that region under diverse climatological conditions that include both El Niño and La Niña events. The basin-averaged rainfall progressively decreases with the increase of deforestation from 2000 to 2030, 2050, and so on, to total deforestation by the end of the twenty-first century. Furthermore, the spatial distribution of rainfall is significantly affected by both the land-cover type and topography. While the massively deforested region experiences an important decrease of precipitation, the areas at the edge of that region and at elevated regions receive more rainfall. Propagating squall lines over the massively deforested region dissipate before reaching the western part of the basin, causing a significant decrease of rainfall that could result in a catastrophic collapse of the ecosystem in that region. The basin experiences much stronger precipitation changes during El Niño events as deforestation increases. During these periods, deforestation in the western part of the basin induces a very significant decrease of precipitation. During wet years, however, deforestation has a minor overall impact on the basin climatology.

scholarly journals Impacto da temperatura da superfície do mar na simulação da Zona de Convergência do Atlântico Sul

2013 ◽  
Vol 28 (3) ◽  
pp. 291-304 ◽  
Author(s):  
Ana Carolina Nóbile Tomaziello ◽  
Adilson Wagner Gandu
Keyword(s):  
El Niño ◽  
El Nino ◽  
Atmospheric Modeling ◽  
La Niña ◽  
Regional Atmospheric Modeling System ◽  
La Nina ◽  
Regional Atmospheric Modeling

Durante o verão austral, diversas regiões do Brasil são afetadas por precipitação intensa, geralmente associada à Zona de Convergência do Atlântico Sul (ZCAS). O objetivo geral deste trabalho foi investigar a influência da resolução espacial e temporal dos dados de temperatura da superfície do mar (TSM) na simulação da precipitação associada à ZCAS. Foram realizadas simulações com o modelo BRAMS (Brazilian developments on the Regional Atmospheric Modeling System) para dois eventos de ZCAS, ocorridos em 1998 (El Niño) e 1999 (La Niña). A quantidade de precipitação acumulada na parte oceânica da ZCAS foi maior nos experimentos com TSM mais quente. Índices estatísticos foram utilizados para verificação do desempenho do modelo na simulação de precipitação nas regiões que compõem a ZCAS (oceânica, costeira e amazônica), com diferentes dados de TSM. A resolução espaço-temporal dos dados de TSM influencia de forma pouco significativa na representação da ZCAS pelo modelo BRAMS. O modelo é mais eficiente em identificar a ocorrência/não ocorrência de chuva do que em localizar núcleos mais intensos e seu desempenho foi superior (inferior) na região amazônica (oceânica) da ZCAS.

scholarly journals Estudo de variabilidade do vento em escala sazonal sobre o nordeste brasileiro utilizando o RAMS: os casos de 1973-1974 e 1982-1983

2011 ◽  
Vol 26 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Juliana Lima Oliveira ◽  
Alexandre Araújo Costa
Keyword(s):  
El Niño ◽  
El Nino ◽  
Atmospheric Modeling ◽  
La Niña ◽  
Regional Atmospheric Modeling System ◽  
La Nina ◽  
Para Determinar ◽  
Regional Atmospheric Modeling

O propósito deste trabalho é analisar a influência da variabilidade climática e os impactos da circulação geral no comportamento dos ventos sobre o Nordeste do Brasil, com enfoque no modelo atmosférico como uma possível ferramenta para previsão de geração de energia eólica. Análises estatísticas sugerem que há uma correlação bastante significativa entre os índices climáticos (índices de El Niño e dipolo) e a intensidade do vento sobre o Nordeste brasileiro, principalmente nos meses de fevereiro a maio, correspondentes à quadra chuvosa. Dados de reanálise do NCEP para eventos de ENOS fortes (El Niño de 1982-83 e La Niña de 1973-74) sugerem que, nesses casos, a influência da circulação geral é tal que eventos fortes de El Niño e La Niña atuam no sentido de intensificar e enfraquecer, respectivamente, os ventos sobre essa região. Como circulações em menor escala, associadas ao sistema de brisa e à forçantes topográficos são bastante relevantes para determinar as características do vento local, o modelo atmosférico de mesoescala Regional Atmospheric Modeling System (RAMS) foi utilizado para simular a velocidade e direção dos ventos de julho a junho de 1982-83 e 1973-74, a fim de estimar a variabilidade dos ventos em escala sazonal e os possíveis impactos dessas variações na produção de energia eólica no Nordeste.

scholarly journals Análise de Aspectos Meteorológicos Sobre o Nordeste do Brasil em Anos de El Niño e La Niña (Analysis of Meteorological Aspects on the Northeast of Brazil in El Niño and La Niña Years)

2011 ◽  
Vol 4 (3) ◽  
pp. 429 ◽  
Author(s):  
Juliana Larise Mendonça Freire ◽  
Jeane Rafaele Araújo Lima ◽  
Enilson Palmeira Cavalcanti
Keyword(s):  
Surface Temperature ◽  
El Niño ◽  
Rainy Season ◽  
El Nino ◽  
Atmospheric Modeling ◽  
La Niña ◽  
Regional Atmospheric Modeling System ◽  
Atmospheric Research ◽  
La Nina ◽  
Regional Atmospheric Modeling

Na elaboração desse trabalho, foram analisadas as diferenças entre os valores das variáveis de temperatura da superfície, vapor d’água e energia potencial convectiva disponível (CAPE) em dois anos de diferentes precipitações pluviométricas na região Nordeste do Brasil (NEB), um ano de El Niño (1998) e um ano de La Niña (2008). O estudo refere-se ao trimestre fevereiro-março-abril (FMA), período chuvoso no Norte do NEB, região mais afetada pelos eventos de El Niño e La Niña. O modelo numérico Brazilian developments on the Regional Atmospheric Modeling System – BRAMS foi utilizado para simular os campos das variáveis referidas. Para a inicialização do modelo BRAMS foram utilizados dados de reanálises 1 do National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR). Além disso, foram utilizados dados de temperatura da superfície do mar (TSM) observada, que foi incluída no modelo como condições de contorno sobre oceano. Os resultados obtidos mostraram que se pode reproduzir aspectos meteorológicos durante eventos de El-Niño/Oscilação Sul, com a utilização do BRAMS. A temperatura da superfície e o vapor d’água apresentaram seus maiores valores no ano seco de 1998, principalmente no Norte do NEB. Os maiores valores da CAPE foram observados na região semiárida no período de La Niña. Palavras-chave: BRAMS, El Niño/La Niña, precipitação   Analysis of Meteorological Aspects on the Northeast of Brazil in El Niño and La Niña Years  ABSTRACT  In the development of this study, have been analyzed the differences between the values of surface temperature, precipitable water and convective available potential energy (CAPE) in two different rainfalls years in Northeast Brazil (NEB), an El Niño year (1998) and a La Niña year (2008). The study refers to the quarter from February to March-April (FMA), the rainy season in northern NEB region most affected by El Niño and La Niña. The numerical model Brazilian developments on the Regional Atmospheric Modeling System - BRAMS was used to simulate the fields of the mentioned variables. For the initialization of the BRAMS model reanalysis data were used by the National Centers for Environment Prediction / National Center for Atmospheric Research (NCEP / NCAR). In addition, have been used data from the observed sea surface temperature (SST), which was included in the model as boundary conditions on the ocean. The results showed that meteorological aspects can play well during ENSO events, using the BRAMS. Surface temperature and water vapor presented their highest values in the dry year of 1998, mainly in northern NEB.The highest values of CAPE were observed in the semiarid region in the rainy season.   Keywords: BRAMS, El Niño/La Niña, precipitation

scholarly journals Detection of Mesoscale Seasonal and Interannual Variation in the Vegetation of the Amazon Basin

2005 ◽  
Vol 9 (25) ◽  
pp. 1-16
Author(s):  
Miles G. Logsdon ◽  
Robin Weeks ◽  
Milton Smith ◽  
Jeffery E. Richey ◽  
Victoria Ballester ◽  
...  
Keyword(s):  
Time Series ◽  
El Niño ◽  
Amazon Basin ◽  
El Nino ◽  
Southern Oscillation ◽  
Mathematical Framework ◽  
Spectral Change ◽  
Range Analysis ◽  
Local Variance ◽  
Wide Range

Abstract In the Amazon basin, seasonal and interannual spectral changes measured by satellites result from anthropogenic disturbance and from the interaction between climate variation and the surface cover. Measurements of spectral change, and the characterization of that change, provide information concerning the physical processes evident at this mesoscale. A 17-yr sequence of daily Advanced Very High Resolution Radiometer (AVHRR) global area coverage (GAC) images were analyzed to produce a monthly record of surface spectral change encompassing El Niño–Southern Oscillation (ENSO) cycles. Monthly cloud-free composite images from daily AVHRR data were produced by linear filters that minimized the finescale spatial variance and allowed for a wide range analysis within a consistent mathematical framework. Here the use of a minimized local variance (MLV) filter that produced spatially smooth images in which major land-cover boundaries and spatial gradients are clearly represented is discussed. Changes in the configuration of these boundaries and the composition of the landscape elements they defined are described in terms of quantitative changes in landscape pattern. The time series produced with the MLV filter revealed a marked seasonal difference in the pattern of the landscape and structural differences over the length of the time series. Strikingly, the response of the region to drier El Niño years appears to be delayed in the MLV series, the maximum response being in the year following El Niño with little or no change seen during El Niño.

Dependence of global monsoon response to volcanic eruptions on the background oceanic states

2021 ◽  
pp. 1-53
Author(s):  
Meng Zuo ◽  
Wenmin Man ◽  
Tianjun Zhou
Keyword(s):  
El Niño ◽  
El Nino ◽  
Volcanic Eruptions ◽  
La Niña ◽  
Initial Condition ◽  
Monsoon Precipitation ◽  
Global Monsoon ◽  
La Nina ◽  
Precipitation Changes ◽  
Sst Anomalies

AbstractBoth proxy data and climate modeling show divergent responses of global monsoon precipitation to volcanic eruptions. The reason is however unknown. Here, based on analysis of the CESM Last Millennium Ensemble simulation, we show evidences that the divergent responses are dominated by the pre-eruption background oceanic states. We found that under El Niño-Southern Oscillation (ENSO) neutral and warm phases initial conditions, the Pacific favors an El Niño-like anomaly after volcanic eruptions, while La Niña-like SST anomalies tend to occur following eruptions under ENSO cold phase initial condition, especially after southern eruptions. The cold initial condition is associated with stronger upper ocean temperature stratification and shallower thermocline over the eastern Pacific than normal. The easterly anomalies triggered by surface cooling over the tropical South America continent can generate changes in SST through anomalous advection and the ocean subsurface upwelling more efficiently, causing La Niña-like SST anomalies. Whereas under warm initial condition, the easterly anomalies fail to develop and the westerly anomalies still play a dominant role, thus forms an El Niño-like SST anomaly. Such SST response further regulates the monsoon precipitation changes through atmospheric teleconnection. The contribution of direct radiative forcing and indirect SST response to precipitation changes show regional differences, which will further affect the intensity and sign of precipitation response in submonsoon regions. Our results imply that attention should be paid to the background oceanic state when predicting the global monsoon precipitation responses to volcanic eruptions.

scholarly journals Limited impact of El Niño–Southern Oscillation on variability and growth rate of atmospheric methane

2018 ◽  
Vol 15 (21) ◽  
pp. 6371-6386 ◽  
Author(s):  
Hinrich Schaefer ◽  
Dan Smale ◽  
Sylvia E. Nichol ◽  
Tony M. Bromley ◽  
Gordon W. Brailsford ◽  
...  
Keyword(s):  
Climate Change ◽  
Growth Rate ◽  
Biomass Burning ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Atmospheric Methane ◽  
Ch4 Production ◽  
A Minor

Abstract. The El Niño–Southern Oscillation (ENSO) has been suggested as a strong forcing in the methane cycle and as a driver of recent trends in global atmospheric methane mole fractions [CH4]. Such a sensitivity of the global CH4 budget to climate events would have important repercussions for climate change mitigation strategies and the accuracy of projections for future greenhouse forcing. Here, we test the impact of ENSO on atmospheric CH4 in a correlation analysis. We use local and global records of [CH4], as well as stable carbon isotopic records of atmospheric CH4 (δ13CH4), which are particularly sensitive to the combined ENSO effects on CH4 production from wetlands and biomass burning. We use a variety of nominal, smoothed, and detrended time series including growth rate records. We find that at most 36 % of the variability in [CH4] and δ13CH4 is attributable to ENSO, but only for detrended records in the southern tropics. Trend-bearing records from the southern tropics, as well as all studied hemispheric and global records, show a minor impact of ENSO, i.e. < 24 % of variability explained. Additional analyses using hydrogen cyanide (HCN) records show a detectable ENSO influence on biomass burning (up to 51 %–55 %), suggesting that it is wetland CH4 production that responds less to ENSO than previously suggested. Dynamics of the removal by hydroxyl likely counteract the variation in emissions, but the expected isotope signal is not evident. It is possible that other processes obscure the ENSO signal, which itself indicates a minor influence of the latter on global CH4 emissions. Trends like the recent rise in atmospheric [CH4] can therefore not be attributed to ENSO. This leaves anthropogenic methane sources as the likely driver, which must be mitigated to reduce anthropogenic climate change.

scholarly journals The Brazilian developments on the Regional Atmospheric Modeling System (BRAMS 5.2): an integrated environmental model tuned for tropical areas

2016 ◽  
Author(s):  
Saulo R. Freitas ◽  
Jairo Panetta ◽  
Karla M. Longo ◽  
Luiz F. Rodrigues ◽  
Demerval S. Moreira ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
South America ◽  
Atmospheric Chemistry ◽  
Amazon Basin ◽  
Carbon Dioxide Concentration ◽  
Atmospheric Modeling ◽  
Tracer Transport ◽  
Regional Atmospheric Modeling System ◽  
Near Surface ◽  
Regional Atmospheric Modeling

Abstract. We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers.

scholarly journals Changes in surface hydrology, soil moisture and gross primary production in the Amazon during the 2015/2016 El Niño

2018 ◽  
Vol 373 (1760) ◽  
pp. 20180084 ◽  
Author(s):  
Erik van Schaik ◽  
Lars Killaars ◽  
Naomi E. Smith ◽  
Gerbrand Koren ◽  
L. P. H. van Beek ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Primary Production ◽  
El Niño ◽  
Amazon Basin ◽  
El Nino ◽  
Gross Primary Production ◽  
Surface Hydrology ◽  
The North ◽  
North Eastern ◽  
The Impact

The 2015/2016 El Niño event caused severe changes in precipitation across the tropics. This impacted surface hydrology, such as river run-off and soil moisture availability, thereby triggering reductions in gross primary production (GPP). Many biosphere models lack the detailed hydrological component required to accurately quantify anomalies in surface hydrology and GPP during droughts in tropical regions. Here, we take the novel approach of coupling the biosphere model SiBCASA with the advanced hydrological model PCR-GLOBWB to attempt such a quantification across the Amazon basin during the drought in 2015/2016. We calculate 30–40% reduced river discharge in the Amazon starting in October 2015, lagging behind the precipitation anomaly by approximately one month and in good agreement with river gauge observations. Soil moisture shows distinctly asymmetrical spatial anomalies with large reductions across the north-eastern part of the basin, which persisted into the following dry season. This added to drought stress in vegetation, already present owing to vapour pressure deficits at the leaf, resulting in a loss of GPP of 0.95 (0.69 to 1.20) PgC between October 2015 and March 2016 compared with the 2007–2014 average. Only 11% (10–12%) of the reduction in GPP was found in the (wetter) north-western part of the basin, whereas the north-eastern and southern regions were affected more strongly, with 56% (54–56%) and 33% (31–33%) of the total, respectively. Uncertainty on this anomaly mostly reflects the unknown rooting depths of vegetation. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

Southeast Asian Forest Fires (1997/1998): El Niño as a Driver of Regional Impacts

2017 ◽  
pp. 191-225 ◽  
Author(s):  
Mohd Talib Latif ◽  
Murnira Othman ◽  
Ahmad Makmom Abdullah ◽  
Md Firoz Khan ◽  
Fatimah Ahamad ◽  
...  
Keyword(s):  
Forest Fires ◽  
El Niño ◽  
El Nino ◽  
Southeast Asian ◽  
Regional Impacts
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