Victor de Morais Danelichen - Academia.edu (original) (raw)
Papers by Victor de Morais Danelichen
AB: The difference in energy that enters and exits a system is the energy used by him. The study ... more AB: The difference in energy that enters and exits a system is the energy used by him. The study of energy exchanges between a vegetated surface and atmosphere is important to identify the interactions between them, knowing the variation of weather and climate of a region and identify the effects of anthropogenic activities. The Bowen ratio method is based on the law of conservation of energy, expressed by the energy balance equation, this method can estimate the latent heat flux and sensible by measures of net radiation, soil heat flux and estimation the gradients of temperature and pressure of water vapor directly measured in the study site. The aim of this study was to estimate the energy balance method of Bowen ratio of the area of mixed pasture in the UFMT's Experimental Farm (15 ° 47'11 "S, 56 ° 04'47" W), located in the northern Pantanal City of Santo Antonio do Leverger -MT to 33km from Cuiabá -MT, altitude of 140m with an annual rainfall of 1320 mm and...
Rainfall is the key element in regional water balance, and have direct influence over economic ac... more Rainfall is the key element in regional water balance, and have direct influence over economic activity. In this study, we evaluate the estimates of precipitation by TRMM satellite (Tropical Rainfall Measuring Mission) on the Midwest region of Brazil. The rainfall measured by TRMM satellite was compared with rainfall series obtained by the Office of Instituto de Controle de Espaço Aéreo (ICEA) of Comando da Força Aérea. The TRMM satellite overestimated annual rainfall between 0.6 and 37.4%, with greater overestimation in the dry season. However, the rainfall estimate by TRMM satellite had a high correlation (0.88) with the rainfall series and had high Willmott coefficient. The Northern of Brazilian Midwest had the highest annual accumulated rainfall and the Southwest and Northeast of Midwest had the lowest annual accumulated rainfall. There was a inverse seasonal pattern of accumulated rainfall, with higher values in the Northern of Midwest during the rainy season in the Southwest a...
Background/Question/Methods: Semi-deciduous forest in the Amazon Basin is sensitive to temporal v... more Background/Question/Methods: Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water availability that can limit seasonal rates of leaf and canopy gas exchange. We estimated seasonal dynamics of gross primary production (GPP) over 3 years (2005-2008) using eddy covariance and assessed canopy spectral reflectance using satellite imagery for a mature tropical semideciduous forest located near Sinop, Mato Grosso, Brazil. A light use efficiency model, known as the vegetation photosynthesis model (VPM), was used to quantify how GPP varied over seasonal and interannual time-scales as a function of rainfall and micrometeorology. Results/Conclusions: Our results indicate that the standard VPM model was incapable of reproducing the seasonal variation in GPP, primarily because the model overestimated dry-season GPP. In the standard model, the scalar function that alters light use efficiency (e ) as a function of water availability (W ) is calculated as a ...
RESUMO: Localizada na Baixada Cuiabana no estado de Mato Grosso, a área de estudo esta situada em... more RESUMO: Localizada na Baixada Cuiabana no estado de Mato Grosso, a área de estudo esta situada em uma região de transição entre o Cerrado e o Pantanal. Na região as áreas de vegetação de Cerrado stricto sensu e Mata Ciliar vem sendo substituída por extensas áreas de pastagens e essa modificação na cobertura do solo é a principal degradação nessa localidade que além de produzir o empobrecimento do solo favorece os processos erosivos. Por meio dos Índices de Vegetação como o: NDVI, SAVI e o IAF, verificou a densidade da vegetação em uma área de pastagem, Mata Ciliar, Cerrado stricto sensu, Mangueiral (Pomar de Manga) e área urbana. O trabalho elaborou cartas do índice de vegetação (NDVI e IAF) em dois períodos no ano de 2009, sendo uma cena no período seco e outra no chuvoso para a avaliação dos efeitos da sazonalidade e as transformações ocorridas na cobertura da superfície pela ocupação do solo. PALAVRA-CHAVE: Vegetação, Solo, Degradação EVALUATION OF VEGETATION INDICES IN AN AREA IN CONDITIONS OF SAVANNAH OF REMOTE SENSING TECHNIQUES USED ABSTRACT: Located in the Baixada Cuiabana in Mato Grosso, the study area is situated in a transitional region between the Cerrado and Pantanal. Areas in the region of Cerrado vegetation strictly and riparian forest has been replaced by large areas of grasslands and this change in land cover is the main degradation in this locality that besides producing the impoverishment of the soil favors erosion. Through Vegetation Index as: NDVI, SAVI and LAI, found the density of vegetation in an area of grassland, riparian forest, cerrado sensu stricto, Mangueiral (Manga orchard) and urban area. The work drew letters of vegetation index (NDVI and LAI) in two periods in 2009, with a scene in the dry and rainy in other to assess the effects of seasonality and the changes occurring in the surface coverage by land use
RESUMO: O crescente incentivo político e social para desenvolvimento de atividades econômicas no ... more RESUMO: O crescente incentivo político e social para desenvolvimento de atividades econômicas no Pantanal têm intensificado o uso e ocupação do solo. Ecossistemas naturais estão sendo rapidamente substituídos por pastagens, modificando o microclima e o funcionamento desses ecossistemas. Dessa forma, o objetivo deste trabalho foi avaliar a mudança no microclima provocada pela conversão de uma floresta de cambará em pastagem no norte do Pantanal. O experimento foi conduzido em uma área de vegetação monodominante de Cambará (Vochysia divergens Pohl) e em uma pastagem mista, onde foram medidas a precipitação, a radiação solar incidente e a temperatura e umidade relativa do ar. A precipitação, radiação solar incidente, temperatura média do ar, temperatura mínima do ar e a umidade relativa média do ar apresentaram sazonalidade com maiores valores na estação chuvosa. A análise realizada indicou mudança significativa do microclima, com significativa diminuição em 16% da precipitação, 8,5% na radiação solar incidente e 5,7% da umidade relativa do ar e aumento de 6,6% na temperatura máxima do ar.
Ciência e Natura, 2014
O Pantanal é considerado a maior planície alagável do mundo, composto de 70% por Cerrado. Nas últ... more O Pantanal é considerado a maior planície alagável do mundo, composto de 70% por Cerrado. Nas últimas décadas, devido ao avanço da agropecuária, grande parte deste bioma tem sido convertido em pastagens. O índice de área foliar (IAF) é uma importante medida da cobertura vegetal, pois, controla as trocas de massa e energia de uma superfície vegetada. Dessa forma o objetivo deste trabalho foi avaliar as estimativas de IAF de uma pastagem no norte do Pantanal Mato-Grossense pelo produto do MODIS (MOD15A2) e pelo modelo proposto por Allen et. al. (2002) com medidas de IAF obtidas por meio da interceptação de luz e precipitação estimada pelo satélite Tropical Rainfall Measuring Mission (TRMM). O estudo foi conduzido em uma pastagem de Brachiaria humidicola (Rendle) Schweick localizada na Fazenda Experimental da Universidade Federal de Mato Grosso, no município de Santo Antônio de Leverger -MT. Os dados de radiação fotossinteticamente ativa incidente, refletida e interceptada na área de estudo foram coletados em um mastro micrometeorológico entre janeiro de 2006 e fevereiro de 2010. O IAF foi medido pelo método da interceptação de luz e estimado pelos modelo proposto por Allen et al. (2002) e pelo produto MODIS. O IAF medido nas pastagem variou interanualmente e sazonalmente com maiores valores durante a estação chuvosa, refletindo a variação da precipitação. O IAF medido e estimado por Allen et al. (2002) não apresentaram correlação com a precipitação, entretanto, o IAF obtido pelo MODIS apresentou a correlação significativa com a precipitação. O IAF medido não correlacionou com o estimado pelo produto MODIS, mas correlacionou com o estimado pelo modelo de Allen et al. (2002). Por meio do teste não-paramétrico de Kruskal Wallis os valores de IAF medidos na pastagem e estimados pelo modelo de Allen et al. (2002) e pelo produto do MODIS apresentaram diferença significativa entre si quando avaliado durante o todo o ano e em cada estação chuvosa e seca. A baixa correlação entre o IAF medido e estimado neste estudo realçam que as estimativas de IAF em pastagens por sensoriamento remoto devem ser utilizadas com cautela. Palavras-chave: microclima, atenuação da radiação, biomassa, mudança do uso do solo.
The gross primary production (GPP) of ecosystems is an important variable in the study of global ... more The gross primary production (GPP) of ecosystems is an important variable in the study of global climate change. Generally, the GPP has been estimated by micrometeorological techniques. However, these techniques have a high cost of implantation and maintenance, making the use of orbital sensor data an option to be evaluated. Thus, the objective of this study was to evaluate the potential of the MODIS (Moderate Resolution Imaging Spectroradiometer) MOD17A2 product and the vegetation photosynthesis model (VPM) to predict the GPP of the Amazon-Cerrado transitional forest. The GPP predicted by MOD17A2 (GPP MODIS ) and VPM (GPP VPM ) were validated with the GPP estimated by eddy covariance (GPP EC ). The GPP MODIS , GPP VPM and GPP EC have similar seasonality, with higher values in the wet season and lower in the dry season. However, the VPM performed was better than the MOD17A2 to estimate the GPP, due to use local climatic data for predict the light use efficiency, while the MOD17A2 use a global circulation model and the lookup table of each vegetation type to estimate the light use efficiency. Keywords: semi-deciduous forest, VPM model, remote sensing and net CO 2 exchange.
Revista Brasileira de Meteorologia, 2014
The direct estimation of the soil heat flux (G) by remote sensing data is not possible. For this,... more The direct estimation of the soil heat flux (G) by remote sensing data is not possible. For this, several models have been proposed empirically from the relation of G measures and biophysical parameters of various types of coverage or not vegetated in different places on earth. Thus, the objective of this study was to evaluate the relation between G/Rn ratio and biophysical variables obtained by satellite sensors and evaluate the parameterization of different models to estimate G spatially in three sites with different soil cover types. The net radiation (Rn) and G were measured directly in two pastures at Miranda Farm and Experimental Farm and and Monodominant Forest of Cambará. Rn, G, and G/Rn ratio and MODIS products, such as albedo (α), surface temperature (LST), vegetation index (NDVI) and leaf area index (LAI) varied seasonally at all sites and inter-sites. The sites were different from each other by presenting different relation between measures of Rn, G and G/Rn ratio and biophysical parameters. Among the original models, the model proposed by showed the best performance with r = 0.76, d = 0.95, MAE = 5.70 W m -2 and RMSE = 33.68 W m -2 . As the reparameterized models, correlation coefficients had no significant change, but the coefficient Willmott (d) increased and the MAE and RMSE had a small decrease.
International Journal of Remote Sensing, 2014
Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water ava... more Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water availability that can limit seasonal rates of leaf and canopy gas exchange. We estimated the seasonal dynamics of gross primary production (GPP) over 3 years (2005)(2006)(2007)(2008) using eddy covariance and assessed canopy spectral reflectance using MODIS imagery for a mature tropical semi-deciduous forest located near Sinop, Mato Grosso, Brazil. A light-use efficiency model, known as the Vegetation Photosynthesis Model (VPM), was used to estimate seasonal and inter-annual variations in GPP as a function of the enhanced vegetation index (EVI), the land surface water index (LSWI), and local meteorology. Our results indicate that the standard VPM was incapable of reproducing the seasonal variation in GPP, primarily because the model overestimated dry-season GPP. In the standard model, the scalar function that alters light-use efficiency (ε g ) as a function of water availability (W scalar ) is calculated as a linear function of the LSWI derived from MODIS; however, the LSWI is negatively correlated with several measures of water availability including precipitation, soil water content, and relative humidity (RH). Thus, during the dry season, when rainfall, soil water content, and RH are low, LSWI, and therefore, W scalar , are at a seasonal maximum. Using previous research, we derived new functions for W scalar based on time series of RH and photosynthetic photon flux density (PPFD) that significantly improved the performance of the VPM. Whether these new functions perform equally well in water stressed and unstressed tropical forests needs to be determined, but presumably unstressed ecosystems would have high cloud cover and humidity, which would minimize variations in W scalar and GPP to spatial and/or temporal variation in water availability.
International Journal of Biometeorology, 2013
Leaf area index (LAI) is a key driver of forest productivity and evapotranspiration; however, it ... more Leaf area index (LAI) is a key driver of forest productivity and evapotranspiration; however, it is a difficult and labor-intensive variable to measure, making its measurement impractical for large-scale and long-term studies of tropical forest structure and function. In contrast, satellite estimates of LAI have shown promise for large-scale and long-term studies, but their performance has been equivocal and the biases are not well known. We measured total, overstory, and understory LAI of an Amazon-savanna transitional forest (ASTF) over 3 years and a seasonal flooded forest (SFF) during 4 years using a light extinction method and two remote sensing methods (LAI MODIS product and the Landsat-METRIC method), with the objectives of (1) evaluating the performance of the remote sensing methods, and (2) understanding how total, overstory and understory LAI interact with micrometeorological variables. Total, overstory and understory LAI differed between both sites, with ASTF having higher LAI values than SFF, but neither site exhibited year-to-year variation in LAI despite large differences in meteorological variables. LAI values at the two sites have different patterns of correlation with micrometeorological variables. ASTF exhibited smaller seasonal variations in LAI than SFF. In contrast, SFF exhibited small changes in total LAI; however, dry season declines in overstory LAI were counteracted by understory increases in LAI. MODIS LAI correlated weakly to total LAI for SFF but not for ASTF, while METRIC LAI had no correlation to total LAI. However, MODIS LAI correlated strongly with overstory LAI for both sites, but had no correlation with understory LAI. Furthermore, LAI estimates based on canopy light extinction were correlated positively with seasonal variations in rainfall and soil water content and negatively with vapor pressure deficit and solar radiation; however, in some cases satellite-derived estimates of LAI exhibited no correlation with climate variables (METRIC LAI or MODIS LAI for ASTF). These data indicate that the satellite-derived estimates of LAI are insensitive to the understory variations in LAI that occur in many seasonal tropical forests and the micrometeorological variables that control seasonal variations in leaf phenology. While more groundbased measurements are needed to adequately quantify the performance of these satellite-based LAI products, our data indicate that their output must be interpreted with caution in seasonal tropical forests.
As propriedades térmicas do solo são resultantes de um conjunto de fatores nos quais se incluem a... more As propriedades térmicas do solo são resultantes de um conjunto de fatores nos quais se incluem a sua textura e composição química. Observações regulares da temperatura do solo em diferentes profundidades possibilitam identificar o seu comportamento térmico e o conhecimento de importantes propriedades, como difusividade térmica do solo. Sendo assim, o objetivo deste trabalho foi determinar a difusividade térmica do solo de uma pastagem no norte do Pantanal por diferentes métodos. A difusividade térmica do solo foi determinada em uma pastagem de Brachiaria humidicola localizada na Fazenda Experimental da Universidade Federal de Mato Grosso em Santo Antônio de Leverger-MT, com coordenadas geográficas (15º47‘11‘‘S; 56º04‘47‘‘O), de longitude oeste e altitude de 120 m acima do nível do mar. O clima local está na classe Aw segundo Köppen e o solo foi classificado como PLANOSSOLO HÁPICO Eutrófico gleissólico. A temperatura do solo foi realizada a 1, 3, 7, 15, 30, 50 e 57 cm de profundidad...
AB: The difference in energy that enters and exits a system is the energy used by him. The study ... more AB: The difference in energy that enters and exits a system is the energy used by him. The study of energy exchanges between a vegetated surface and atmosphere is important to identify the interactions between them, knowing the variation of weather and climate of a region and identify the effects of anthropogenic activities. The Bowen ratio method is based on the law of conservation of energy, expressed by the energy balance equation, this method can estimate the latent heat flux and sensible by measures of net radiation, soil heat flux and estimation the gradients of temperature and pressure of water vapor directly measured in the study site. The aim of this study was to estimate the energy balance method of Bowen ratio of the area of mixed pasture in the UFMT's Experimental Farm (15 ° 47'11 "S, 56 ° 04'47" W), located in the northern Pantanal City of Santo Antonio do Leverger -MT to 33km from Cuiabá -MT, altitude of 140m with an annual rainfall of 1320 mm and...
Rainfall is the key element in regional water balance, and have direct influence over economic ac... more Rainfall is the key element in regional water balance, and have direct influence over economic activity. In this study, we evaluate the estimates of precipitation by TRMM satellite (Tropical Rainfall Measuring Mission) on the Midwest region of Brazil. The rainfall measured by TRMM satellite was compared with rainfall series obtained by the Office of Instituto de Controle de Espaço Aéreo (ICEA) of Comando da Força Aérea. The TRMM satellite overestimated annual rainfall between 0.6 and 37.4%, with greater overestimation in the dry season. However, the rainfall estimate by TRMM satellite had a high correlation (0.88) with the rainfall series and had high Willmott coefficient. The Northern of Brazilian Midwest had the highest annual accumulated rainfall and the Southwest and Northeast of Midwest had the lowest annual accumulated rainfall. There was a inverse seasonal pattern of accumulated rainfall, with higher values in the Northern of Midwest during the rainy season in the Southwest a...
Background/Question/Methods: Semi-deciduous forest in the Amazon Basin is sensitive to temporal v... more Background/Question/Methods: Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water availability that can limit seasonal rates of leaf and canopy gas exchange. We estimated seasonal dynamics of gross primary production (GPP) over 3 years (2005-2008) using eddy covariance and assessed canopy spectral reflectance using satellite imagery for a mature tropical semideciduous forest located near Sinop, Mato Grosso, Brazil. A light use efficiency model, known as the vegetation photosynthesis model (VPM), was used to quantify how GPP varied over seasonal and interannual time-scales as a function of rainfall and micrometeorology. Results/Conclusions: Our results indicate that the standard VPM model was incapable of reproducing the seasonal variation in GPP, primarily because the model overestimated dry-season GPP. In the standard model, the scalar function that alters light use efficiency (e ) as a function of water availability (W ) is calculated as a ...
RESUMO: Localizada na Baixada Cuiabana no estado de Mato Grosso, a área de estudo esta situada em... more RESUMO: Localizada na Baixada Cuiabana no estado de Mato Grosso, a área de estudo esta situada em uma região de transição entre o Cerrado e o Pantanal. Na região as áreas de vegetação de Cerrado stricto sensu e Mata Ciliar vem sendo substituída por extensas áreas de pastagens e essa modificação na cobertura do solo é a principal degradação nessa localidade que além de produzir o empobrecimento do solo favorece os processos erosivos. Por meio dos Índices de Vegetação como o: NDVI, SAVI e o IAF, verificou a densidade da vegetação em uma área de pastagem, Mata Ciliar, Cerrado stricto sensu, Mangueiral (Pomar de Manga) e área urbana. O trabalho elaborou cartas do índice de vegetação (NDVI e IAF) em dois períodos no ano de 2009, sendo uma cena no período seco e outra no chuvoso para a avaliação dos efeitos da sazonalidade e as transformações ocorridas na cobertura da superfície pela ocupação do solo. PALAVRA-CHAVE: Vegetação, Solo, Degradação EVALUATION OF VEGETATION INDICES IN AN AREA IN CONDITIONS OF SAVANNAH OF REMOTE SENSING TECHNIQUES USED ABSTRACT: Located in the Baixada Cuiabana in Mato Grosso, the study area is situated in a transitional region between the Cerrado and Pantanal. Areas in the region of Cerrado vegetation strictly and riparian forest has been replaced by large areas of grasslands and this change in land cover is the main degradation in this locality that besides producing the impoverishment of the soil favors erosion. Through Vegetation Index as: NDVI, SAVI and LAI, found the density of vegetation in an area of grassland, riparian forest, cerrado sensu stricto, Mangueiral (Manga orchard) and urban area. The work drew letters of vegetation index (NDVI and LAI) in two periods in 2009, with a scene in the dry and rainy in other to assess the effects of seasonality and the changes occurring in the surface coverage by land use
RESUMO: O crescente incentivo político e social para desenvolvimento de atividades econômicas no ... more RESUMO: O crescente incentivo político e social para desenvolvimento de atividades econômicas no Pantanal têm intensificado o uso e ocupação do solo. Ecossistemas naturais estão sendo rapidamente substituídos por pastagens, modificando o microclima e o funcionamento desses ecossistemas. Dessa forma, o objetivo deste trabalho foi avaliar a mudança no microclima provocada pela conversão de uma floresta de cambará em pastagem no norte do Pantanal. O experimento foi conduzido em uma área de vegetação monodominante de Cambará (Vochysia divergens Pohl) e em uma pastagem mista, onde foram medidas a precipitação, a radiação solar incidente e a temperatura e umidade relativa do ar. A precipitação, radiação solar incidente, temperatura média do ar, temperatura mínima do ar e a umidade relativa média do ar apresentaram sazonalidade com maiores valores na estação chuvosa. A análise realizada indicou mudança significativa do microclima, com significativa diminuição em 16% da precipitação, 8,5% na radiação solar incidente e 5,7% da umidade relativa do ar e aumento de 6,6% na temperatura máxima do ar.
Ciência e Natura, 2014
O Pantanal é considerado a maior planície alagável do mundo, composto de 70% por Cerrado. Nas últ... more O Pantanal é considerado a maior planície alagável do mundo, composto de 70% por Cerrado. Nas últimas décadas, devido ao avanço da agropecuária, grande parte deste bioma tem sido convertido em pastagens. O índice de área foliar (IAF) é uma importante medida da cobertura vegetal, pois, controla as trocas de massa e energia de uma superfície vegetada. Dessa forma o objetivo deste trabalho foi avaliar as estimativas de IAF de uma pastagem no norte do Pantanal Mato-Grossense pelo produto do MODIS (MOD15A2) e pelo modelo proposto por Allen et. al. (2002) com medidas de IAF obtidas por meio da interceptação de luz e precipitação estimada pelo satélite Tropical Rainfall Measuring Mission (TRMM). O estudo foi conduzido em uma pastagem de Brachiaria humidicola (Rendle) Schweick localizada na Fazenda Experimental da Universidade Federal de Mato Grosso, no município de Santo Antônio de Leverger -MT. Os dados de radiação fotossinteticamente ativa incidente, refletida e interceptada na área de estudo foram coletados em um mastro micrometeorológico entre janeiro de 2006 e fevereiro de 2010. O IAF foi medido pelo método da interceptação de luz e estimado pelos modelo proposto por Allen et al. (2002) e pelo produto MODIS. O IAF medido nas pastagem variou interanualmente e sazonalmente com maiores valores durante a estação chuvosa, refletindo a variação da precipitação. O IAF medido e estimado por Allen et al. (2002) não apresentaram correlação com a precipitação, entretanto, o IAF obtido pelo MODIS apresentou a correlação significativa com a precipitação. O IAF medido não correlacionou com o estimado pelo produto MODIS, mas correlacionou com o estimado pelo modelo de Allen et al. (2002). Por meio do teste não-paramétrico de Kruskal Wallis os valores de IAF medidos na pastagem e estimados pelo modelo de Allen et al. (2002) e pelo produto do MODIS apresentaram diferença significativa entre si quando avaliado durante o todo o ano e em cada estação chuvosa e seca. A baixa correlação entre o IAF medido e estimado neste estudo realçam que as estimativas de IAF em pastagens por sensoriamento remoto devem ser utilizadas com cautela. Palavras-chave: microclima, atenuação da radiação, biomassa, mudança do uso do solo.
The gross primary production (GPP) of ecosystems is an important variable in the study of global ... more The gross primary production (GPP) of ecosystems is an important variable in the study of global climate change. Generally, the GPP has been estimated by micrometeorological techniques. However, these techniques have a high cost of implantation and maintenance, making the use of orbital sensor data an option to be evaluated. Thus, the objective of this study was to evaluate the potential of the MODIS (Moderate Resolution Imaging Spectroradiometer) MOD17A2 product and the vegetation photosynthesis model (VPM) to predict the GPP of the Amazon-Cerrado transitional forest. The GPP predicted by MOD17A2 (GPP MODIS ) and VPM (GPP VPM ) were validated with the GPP estimated by eddy covariance (GPP EC ). The GPP MODIS , GPP VPM and GPP EC have similar seasonality, with higher values in the wet season and lower in the dry season. However, the VPM performed was better than the MOD17A2 to estimate the GPP, due to use local climatic data for predict the light use efficiency, while the MOD17A2 use a global circulation model and the lookup table of each vegetation type to estimate the light use efficiency. Keywords: semi-deciduous forest, VPM model, remote sensing and net CO 2 exchange.
Revista Brasileira de Meteorologia, 2014
The direct estimation of the soil heat flux (G) by remote sensing data is not possible. For this,... more The direct estimation of the soil heat flux (G) by remote sensing data is not possible. For this, several models have been proposed empirically from the relation of G measures and biophysical parameters of various types of coverage or not vegetated in different places on earth. Thus, the objective of this study was to evaluate the relation between G/Rn ratio and biophysical variables obtained by satellite sensors and evaluate the parameterization of different models to estimate G spatially in three sites with different soil cover types. The net radiation (Rn) and G were measured directly in two pastures at Miranda Farm and Experimental Farm and and Monodominant Forest of Cambará. Rn, G, and G/Rn ratio and MODIS products, such as albedo (α), surface temperature (LST), vegetation index (NDVI) and leaf area index (LAI) varied seasonally at all sites and inter-sites. The sites were different from each other by presenting different relation between measures of Rn, G and G/Rn ratio and biophysical parameters. Among the original models, the model proposed by showed the best performance with r = 0.76, d = 0.95, MAE = 5.70 W m -2 and RMSE = 33.68 W m -2 . As the reparameterized models, correlation coefficients had no significant change, but the coefficient Willmott (d) increased and the MAE and RMSE had a small decrease.
International Journal of Remote Sensing, 2014
Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water ava... more Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water availability that can limit seasonal rates of leaf and canopy gas exchange. We estimated the seasonal dynamics of gross primary production (GPP) over 3 years (2005)(2006)(2007)(2008) using eddy covariance and assessed canopy spectral reflectance using MODIS imagery for a mature tropical semi-deciduous forest located near Sinop, Mato Grosso, Brazil. A light-use efficiency model, known as the Vegetation Photosynthesis Model (VPM), was used to estimate seasonal and inter-annual variations in GPP as a function of the enhanced vegetation index (EVI), the land surface water index (LSWI), and local meteorology. Our results indicate that the standard VPM was incapable of reproducing the seasonal variation in GPP, primarily because the model overestimated dry-season GPP. In the standard model, the scalar function that alters light-use efficiency (ε g ) as a function of water availability (W scalar ) is calculated as a linear function of the LSWI derived from MODIS; however, the LSWI is negatively correlated with several measures of water availability including precipitation, soil water content, and relative humidity (RH). Thus, during the dry season, when rainfall, soil water content, and RH are low, LSWI, and therefore, W scalar , are at a seasonal maximum. Using previous research, we derived new functions for W scalar based on time series of RH and photosynthetic photon flux density (PPFD) that significantly improved the performance of the VPM. Whether these new functions perform equally well in water stressed and unstressed tropical forests needs to be determined, but presumably unstressed ecosystems would have high cloud cover and humidity, which would minimize variations in W scalar and GPP to spatial and/or temporal variation in water availability.
International Journal of Biometeorology, 2013
Leaf area index (LAI) is a key driver of forest productivity and evapotranspiration; however, it ... more Leaf area index (LAI) is a key driver of forest productivity and evapotranspiration; however, it is a difficult and labor-intensive variable to measure, making its measurement impractical for large-scale and long-term studies of tropical forest structure and function. In contrast, satellite estimates of LAI have shown promise for large-scale and long-term studies, but their performance has been equivocal and the biases are not well known. We measured total, overstory, and understory LAI of an Amazon-savanna transitional forest (ASTF) over 3 years and a seasonal flooded forest (SFF) during 4 years using a light extinction method and two remote sensing methods (LAI MODIS product and the Landsat-METRIC method), with the objectives of (1) evaluating the performance of the remote sensing methods, and (2) understanding how total, overstory and understory LAI interact with micrometeorological variables. Total, overstory and understory LAI differed between both sites, with ASTF having higher LAI values than SFF, but neither site exhibited year-to-year variation in LAI despite large differences in meteorological variables. LAI values at the two sites have different patterns of correlation with micrometeorological variables. ASTF exhibited smaller seasonal variations in LAI than SFF. In contrast, SFF exhibited small changes in total LAI; however, dry season declines in overstory LAI were counteracted by understory increases in LAI. MODIS LAI correlated weakly to total LAI for SFF but not for ASTF, while METRIC LAI had no correlation to total LAI. However, MODIS LAI correlated strongly with overstory LAI for both sites, but had no correlation with understory LAI. Furthermore, LAI estimates based on canopy light extinction were correlated positively with seasonal variations in rainfall and soil water content and negatively with vapor pressure deficit and solar radiation; however, in some cases satellite-derived estimates of LAI exhibited no correlation with climate variables (METRIC LAI or MODIS LAI for ASTF). These data indicate that the satellite-derived estimates of LAI are insensitive to the understory variations in LAI that occur in many seasonal tropical forests and the micrometeorological variables that control seasonal variations in leaf phenology. While more groundbased measurements are needed to adequately quantify the performance of these satellite-based LAI products, our data indicate that their output must be interpreted with caution in seasonal tropical forests.
As propriedades térmicas do solo são resultantes de um conjunto de fatores nos quais se incluem a... more As propriedades térmicas do solo são resultantes de um conjunto de fatores nos quais se incluem a sua textura e composição química. Observações regulares da temperatura do solo em diferentes profundidades possibilitam identificar o seu comportamento térmico e o conhecimento de importantes propriedades, como difusividade térmica do solo. Sendo assim, o objetivo deste trabalho foi determinar a difusividade térmica do solo de uma pastagem no norte do Pantanal por diferentes métodos. A difusividade térmica do solo foi determinada em uma pastagem de Brachiaria humidicola localizada na Fazenda Experimental da Universidade Federal de Mato Grosso em Santo Antônio de Leverger-MT, com coordenadas geográficas (15º47‘11‘‘S; 56º04‘47‘‘O), de longitude oeste e altitude de 120 m acima do nível do mar. O clima local está na classe Aw segundo Köppen e o solo foi classificado como PLANOSSOLO HÁPICO Eutrófico gleissólico. A temperatura do solo foi realizada a 1, 3, 7, 15, 30, 50 e 57 cm de profundidad...