Proceedings of the National Academy of Sciences of the United States of America, Jan 27, 2016
For half a century, the process of economic integration of the Amazon has been based on intensive... more For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two "tipping points," namely, temperature increase of 4 °C or deforestation exceeding 40% of the forest area. If transgressed, large-scale "savannization" of mostly southern and eastern Amazon may take place. The region has warmed about 1 °C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in de...
Recentemente Ambrizzi et al. (2007), utilizando três modelos regionais que foram integrados numer... more Recentemente Ambrizzi et al. (2007), utilizando três modelos regionais que foram integrados numericamente para a América do Sul, a partir de dados iniciais obtidos do modelo climático global do Hadley Centre, concluíram que para o período 2071-2100, em relação ao ...
As circulações locais são circulações de ar induzidas termi¬camente pelos processos de superfície... more As circulações locais são circulações de ar induzidas termi¬camente pelos processos de superfície em regiões heterogêneas. Essas circulações podem ser as convencionais, ou seja, surgem em virtude de aquecimento diferencial, como a circulações de "brisa marítima/terrestre", vale-montanha, lacustre, ou as não convencionais, como as induzidas por diferenças em umidade de solo ou vegetação. As brisas (marítimas, terrestres, lacustres, de vegetação, de vale-montanha) têm grande influência no c1ima em diver¬sas partes do globo. Por exemplo, próximo as costa, num dia quente, com vento fraco, ha maior aquecimento da areia e do solo do que da água do mar. Isto porque a água tem ca¬pacidade calorífica maior que materiais como areia e solo, e para aquecê-la e necessário maior quantidade de calor. Esse aquecimento diferencial gera diferença regional de pressão atmosférica, ficando o ar mais quente sobre o conti¬nente com pressão relativamente mais baixa do que o ar mais frio sobre 0 m...
This article documents the intensity of the 1997-98 El Niño episode and its effects over Brazil. ... more This article documents the intensity of the 1997-98 El Niño episode and its effects over Brazil. The mean SST anomaly of 3.92°C over the Niño 3 region in the equatorial Pacific in December 1997 surpassed the record in the last 50 years. On the average southern Brazil received 30-50 mm/month more rain than climatology during October 97 through May 1997. Most parts of Northeast Brazil registered a deficit of about 200 mm during 1998 rainy season, February through May. The temperatures in the southcentral Brazil during the 1997 winter remained 1-2°C above normal.
As an attempt to obtain the skill for CPTEC/COLA General Circulation Model with a resolution of T... more As an attempt to obtain the skill for CPTEC/COLA General Circulation Model with a resolution of T62L28 (it means: horizontal resolution of 1.875o X 1.875o, and vertical resolution of 28 levels using sigma coordinates), correlation coefficients between observed and predicted fields for February-March-April-May were calculated for five different regions in Brazil. Two different SST anomaly patterns were used: Pacific plus Atlantic predicted SST anomalies and Pacific plus Atlantic persisted SST anomalies. Results presented below show that a lot must be done to provide good quantitative forecasts. Qualitative results are quite reasonable for climate prediction.
O Brasil, por ser um país de grande extensão territorial, possui diferenciados regimes de precipi... more O Brasil, por ser um país de grande extensão territorial, possui diferenciados regimes de precipitação e temperatura. De norte a sul encontra-se uma grande variedade de climas com distintas características regionais. No norte do país verifica-se um clima equatorial chuvoso, praticamente sem estação seca. No Nordeste a estação chuvosa, com baixos índices pluviométricos, restringe-se a poucos meses, caracterizando um clima semi-árido. As Regiões Sudeste e Centro-Oeste sofrem influência tanto de sistemas tropicais como de latitudes médias, com estação seca bem definida no inverno e estação chuvosa de verão com chuvas convectivas. O sul do Brasil, devido à sua localização latitudinal, sofre mais influência dos sistemas de latitudes médias, onde os sistemas frontais são os principais causadores de chuvas durante o ano.
This paper addresses important questions about ensemble climate forecasting system. Given an atmo... more This paper addresses important questions about ensemble climate forecasting system. Given an atmospheric general circulation model (AGCM) ensemble run with a large number of independent integrations, is there a subensemble whose mean, in principle, improves the forecast performance? Is there a way to identify a priori (before running the forecast integrations) a subensemble whose mean can possibly give a performance better or equal to the performance of the whole ensemble? The model is essentially run in forecast mode with fixed SST anomalies and predicted SST anomalies using 25 members. To answer these questions, a subgroup of members with the anomaly correlation coefficient (CCA) equal to or greater than CCA of the complete ensemble during the spin up period are chosen. The mean of the forecasts based on this subset is found to have a spatial correlation with the observed precipitation of the same order of the complete ensemble. The size of this subset is found to be around 9 memb...
Proceedings of the National Academy of Sciences of the United States of America, Jan 27, 2016
For half a century, the process of economic integration of the Amazon has been based on intensive... more For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two "tipping points," namely, temperature increase of 4 °C or deforestation exceeding 40% of the forest area. If transgressed, large-scale "savannization" of mostly southern and eastern Amazon may take place. The region has warmed about 1 °C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in de...
Recentemente Ambrizzi et al. (2007), utilizando três modelos regionais que foram integrados numer... more Recentemente Ambrizzi et al. (2007), utilizando três modelos regionais que foram integrados numericamente para a América do Sul, a partir de dados iniciais obtidos do modelo climático global do Hadley Centre, concluíram que para o período 2071-2100, em relação ao ...
As circulações locais são circulações de ar induzidas termi¬camente pelos processos de superfície... more As circulações locais são circulações de ar induzidas termi¬camente pelos processos de superfície em regiões heterogêneas. Essas circulações podem ser as convencionais, ou seja, surgem em virtude de aquecimento diferencial, como a circulações de "brisa marítima/terrestre", vale-montanha, lacustre, ou as não convencionais, como as induzidas por diferenças em umidade de solo ou vegetação. As brisas (marítimas, terrestres, lacustres, de vegetação, de vale-montanha) têm grande influência no c1ima em diver¬sas partes do globo. Por exemplo, próximo as costa, num dia quente, com vento fraco, ha maior aquecimento da areia e do solo do que da água do mar. Isto porque a água tem ca¬pacidade calorífica maior que materiais como areia e solo, e para aquecê-la e necessário maior quantidade de calor. Esse aquecimento diferencial gera diferença regional de pressão atmosférica, ficando o ar mais quente sobre o conti¬nente com pressão relativamente mais baixa do que o ar mais frio sobre 0 m...
This article documents the intensity of the 1997-98 El Niño episode and its effects over Brazil. ... more This article documents the intensity of the 1997-98 El Niño episode and its effects over Brazil. The mean SST anomaly of 3.92°C over the Niño 3 region in the equatorial Pacific in December 1997 surpassed the record in the last 50 years. On the average southern Brazil received 30-50 mm/month more rain than climatology during October 97 through May 1997. Most parts of Northeast Brazil registered a deficit of about 200 mm during 1998 rainy season, February through May. The temperatures in the southcentral Brazil during the 1997 winter remained 1-2°C above normal.
As an attempt to obtain the skill for CPTEC/COLA General Circulation Model with a resolution of T... more As an attempt to obtain the skill for CPTEC/COLA General Circulation Model with a resolution of T62L28 (it means: horizontal resolution of 1.875o X 1.875o, and vertical resolution of 28 levels using sigma coordinates), correlation coefficients between observed and predicted fields for February-March-April-May were calculated for five different regions in Brazil. Two different SST anomaly patterns were used: Pacific plus Atlantic predicted SST anomalies and Pacific plus Atlantic persisted SST anomalies. Results presented below show that a lot must be done to provide good quantitative forecasts. Qualitative results are quite reasonable for climate prediction.
O Brasil, por ser um país de grande extensão territorial, possui diferenciados regimes de precipi... more O Brasil, por ser um país de grande extensão territorial, possui diferenciados regimes de precipitação e temperatura. De norte a sul encontra-se uma grande variedade de climas com distintas características regionais. No norte do país verifica-se um clima equatorial chuvoso, praticamente sem estação seca. No Nordeste a estação chuvosa, com baixos índices pluviométricos, restringe-se a poucos meses, caracterizando um clima semi-árido. As Regiões Sudeste e Centro-Oeste sofrem influência tanto de sistemas tropicais como de latitudes médias, com estação seca bem definida no inverno e estação chuvosa de verão com chuvas convectivas. O sul do Brasil, devido à sua localização latitudinal, sofre mais influência dos sistemas de latitudes médias, onde os sistemas frontais são os principais causadores de chuvas durante o ano.
This paper addresses important questions about ensemble climate forecasting system. Given an atmo... more This paper addresses important questions about ensemble climate forecasting system. Given an atmospheric general circulation model (AGCM) ensemble run with a large number of independent integrations, is there a subensemble whose mean, in principle, improves the forecast performance? Is there a way to identify a priori (before running the forecast integrations) a subensemble whose mean can possibly give a performance better or equal to the performance of the whole ensemble? The model is essentially run in forecast mode with fixed SST anomalies and predicted SST anomalies using 25 members. To answer these questions, a subgroup of members with the anomaly correlation coefficient (CCA) equal to or greater than CCA of the complete ensemble during the spin up period are chosen. The mean of the forecasts based on this subset is found to have a spatial correlation with the observed precipitation of the same order of the complete ensemble. The size of this subset is found to be around 9 memb...
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