SEBAL Algorithm Research Articles

Quantification of cotton water consumption by remote sensing

Quantifying crop water consumption is essential for water resource management. The objective was to estimate the current evapotranspiration (ETa) of the cotton crop (Gossypium hirsutum L.) in the rainfed system, as well as the components of the radiation and energy balance in the Cerrado biome conditions using orbital images and the SEBAL algorithm and validate the estimates of evapotranspiration (ET) using FAO guidelines for crop coefficient (K c) of the cotton crop. Research was carried out in the State of Mato Grosso, Brazil, in areas with three cotton cultivars. Images of the Operational Land Imager and Thermal Infrared Sensor sensors were used and ET estimation was made based on the SEBAL algorithm. Mean ETa in the cotton cycle was 3.5 mm dia−1 and the K c values ranged from 0.22 and 1.12, on average, in the smaller and larger leaf area, respectively.

Comparison of SEBS and SEBAL Algorithms in Evaporation Estimation from Open Water Surface with the Assessment of the Salinity Effect

Comparison of SEBS and SEBAL Algorithms in Evaporation Estimation from Open Water Surface with the Assessment of the Salinity Effect

Albedo Trend Analyses in Atlantic Forest Biome Areas

The albedo is an important variable that controls the balance of radiation and energy of the atmosphere, so changes in land cover cause alterations in albedo values, influencing changes in climate behavior at different scales. The goal in this work was to investigate the possible occurrence and causes associated with surface albedo trends within the Atlantic Forest biome (São Francisco de Paula, state of Rio Grande do Sul, Brazil), during the last thirty years (1987-2017), evaluating the impacts of the forest cover structure on albedo trends. The study included images of the TM/Landsat 5 and OLI/Landsat 8 sensors over the period 1987 to 2017. The surface albedo was obtained from the SEBAL algorithm, which includes in its variables the reflectance values of each band, reflected solar radiation and atmospheric transmissivity. The trend analysis was performed by the Mann-Kendall test verifying the existence of significant trends over 30 years. Subsequently, the influence of vegetation greenness on the trend presented by the albedo surface was evaluated. Approximately 92% of the pixels with significant tendency are associated with the decreasing tendency of the albedo. The downward trend was observed with the change from the field to the forest cover, while increasing trends were influenced by the change in forest cover, such as the suppression of individuals from the upper forest canopy. The forest populations in areas of the Mata Atlântica biome had a large participation in the energy balance, which exposed a reduction of approximately 60% of the surface albedo with its implantation, showing its importance for reducing the emission of energy to the atmosphere. The spatial pattern of the trend distribution of the surface albedo is related to the concentration and vigor of the arboreal vegetation.

Determination of maize water requirement using remote sensing data and SEBAL algorithm

Efficient agricultural water demand management in arid and semi-arid regions is key in continuing crop production in a changing climate. As such, there’s a need for further investigation on various crops to identify the optimum water requirements to avoid water wasting in regions that are already facing water shortage. The focus of this work is to determine water requirement maize farming Mazandaran Province in Northern Iran, located on the southern side of the Caspian Sea, using Landsat satellite data. In order to use SEBAL algorithm, the images were atmospheric calibrated. Evapotranspiration maps with RMSE values equals to 0.73, 1.38 and 0.74 mm/day were produced and compared to Reference Book (RB), National Water Document (NWD) and FAO56 values. Furthermore, by computing reference evapotranspiration, crop coefficient curve was evaluated. In order to prepare maize water requirement maps, ET0 in 58 weather stations throughout the province were computed and interpolated. By using the daily ET0 maps and resulted Kc values, maize water requirement maps for the cultivated area of the province were 345.16–383.99 mm. The maize water requirement in the observation station of Sari compared to RB and NWD values showed −%20 and +%41 differences and RMSE was 76 and 156 mm, respectively.

Spatial distribution of biophysical parameters in the Ipanema River Basin using remote sensing techniques

Remote sensing techniques obtain essential information about the biophysical parameters at the interface earth's surface and atmosphere that are important for observing the vegetation conditions in the different land uses and occupations, especially in survey directed to hydrographic basins. The objective of this study was to evaluate the spatial distribution of biophysical parameters in the Ipanema River basin by remote sensing. An image of Landsat 8 OLI/TIRS satellite was used, on the date of passage November 14, 2015, covering the all study area of Ipanema River basin, located in the Brazilian semiarid region. The image was processed by ERDAS IMAGINE® 9.1 Software. Radiometric calibration and conversion to radiance and reflectance were performed with the surface data using the SEBAL algorithm. The meteorological data were collected from an automatic station belonging to INMET, located in the study area. The thematic maps of the biophysical parameters albedo, land surface temperature (Tsup) and the radiation balance (Rn) were processed by ArcGIS® 10.2.2 Software. The descriptive statistics were used to determine the differences of these parameters in relation to the local climate of the region and anthropic actions. Radiation balance (Rn) was closely related to the albedo spatial patterns and surface temperature. The highest values of Rn were represented by the lowest albedo values. The results obtained corroborate with those present in the literature and show spectral behavior typical of targets that integrate the classes of land use and occupation in the semiarid region during the dry season, evidencing that the SEBAL algorithm can be used with great potential for estimation of radiation balance.

Space-temporal evaluation of biophysical parameters in the High Ipanema watershed by remote sensing

The High Ipanema watershed is located in a semiarid region and because of this, becomes more vulnerable and susceptible to the effects of environmental changes and the degradation process, it has serious economic and socio-environmental implications. In recent years with the advancement of remote sensing based on satellite imagery or other platforms, it has become possible to monitor different and large areas of the various biomes in the world. The objective of this study was to identify changes in the vegetation cover conditions in the Alto Ipanema watershed, using spectral analyzes of Landsat-8 OLI / TIRS satellite images, using remote sensing techniques. Landsat-8 OLI / TIRS satellite images were obtained from the United States Geological Survey – USGS, on 10/12/2013, 14/01/2015 and 12/08/2016, where they were processed from ERDAS IMAGINE® Software, version 9.1. The thematic maps of biophysical parameters were processed by ArcGis® 10.2.2 Software. With the biophysical parameters analyzed, it was found that the northwest portion of the watershed presents a considerable area of exposed soils with indication of a high degree of susceptibility to degradation and that the biophysical parameters evaluated by the SEBAL algorithm are efficient in understanding the dynamics of spatial and temporal areas of semiarid environments.

Quantile technique to precipitation, rainfall anomaly index and biophysical parameters by remote sensing in Serra Talhada, Pernambuco

The occurrence of extreme events is a current reality that causes socioeconomic and environmental damages in the world. Increasingly, the occurrence of these events and their relation to anthropic actions are being investigated. Several methods have been used to identify and characterize extreme events to precipitation, mainly the quantile technique and the rainfall anomaly index (RAI). The objective of this paper was to identify years with extreme events to precipitation and to evaluate biophysical parameters to the surface by remote sensing through the use of orbital images. Parameters such as surface albedo, Normalized Difference Vegetation Index (NDVI) for years with extreme events were estimated using the ERDAS IMAGINE® 9.1 Software, from the implementation of the SEBAL algorithm. The study area is located in the municipality of Serra Talhada, Pernambuco. The thematic maps of the region were generated from the ArcGIS® 10.2.2 Software. For the Quantile of the years 1993, 1998, 2012, 2016 were classified as very dry, and for RAI the years 1993, 1998, 2012 were classified as extremely dry. The main differences between albedo and NDVI were observed through descriptive statistics. Quantile technique allowed the classification of annual precipitations, showing the interannual rainfall variability in the years 2011 and 2012, also confirming that the average for the normal years is characteristic of the semi-arid region. RAI allowed to identify the largest extreme events of precipitation in the years 1989 and 1998. The surface albedo had little variation due to the spatial and temporal analysis of the images, as did the NDVI. However, both the rainfall anomaly index and the Quantile technique are relevant and effective tools for rainfall classification and the remote sensing techniques as a tool to investigate the use and occupation of the soil, proved to be of great importance, helping the management and conservation of the soil.

Satellite-based ET estimation using Landsat 8 images and SEBAL model

Estimation of evapotranspiration is a key factor to achieve sustainable water management in irrigated agriculture because it represents water use of crops. Satellite-based estimations provide advantages compared to direct methods as lysimeters especially when the objective is to calculate evapotranspiration at a regional scale. The present study aimed to estimate the actual evapotranspiration (ET) at a regional scale, using Landsat 8 - OLI/TIRS images and complementary data collected from a weather station. SEBAL model was used in South-West Parana, region composed of irrigated and dry agricultural areas, native vegetation and urban areas. Five Landsat 8 images, row 223 and path 78, DOY 336/2013, 19/2014, 35/2014, 131/2014 and 195/2014 were used, from which ET at daily scale was estimated as a residual of the surface energy balance to produce ET maps. The steps for obtain ET using SEBAL include radiometric calibration, calculation of the reflectance, surface albedo, vegetation indexes (NDVI, SAVI and LAI) and emissivity. These parameters were obtained based on the reflective bands of the orbital sensor with temperature surface estimated from thermal band. The estimated ET values in agricultural areas, native vegetation and urban areas using SEBAL algorithm were compatible with those shown in the literature and ET errors between the ET estimates from SEBAL model and Penman Monteith FAO 56 equation were less than or equal to 1.00 mm day-1.

Spatial and temporal distribution of soil moisture using remote sensing techniques

The determination of soil moisture distribution is complex and timely, making it unable to describe the behavior of its spatial and temporal distribution on a regional scale. The objective of this study was to estimate and evaluate the spatial and temporal variability of soil moisture by means of the instantaneous evaporative fraction in the semi-arid region using remote sensing data. Three images of the Landsat 5 sensor satellite TM were used on September 21, 2008, June 20, 2009 and August 29, 2011, covering the area of study: Iguatu, Brazilian semiarid. These images were processed from the ERDAS imagine 9.1 software, where the radiometric calibration and the conversion to radiance and reflectance were performed through complementary surface data using the SEBAL algorithm. The thematic maps of the energy balance biophysical parameters: instantaneous evaporative fraction (FE) and the degree of soil moisture saturation (θ / θsat) were processed by ArcGis® 10.2.2 software. The descriptive statistics was used to determine the differences of FE and θ / θsat in relation to the anthropological actions and the local climate of the region. Therefore, the monitoring of these biophysical parameters, especially the degree of soil moisture saturation, showed to be an effective part of the energy balance, configuring before them the power to make decisions regarding environmental aspects. The estimation of the spatial pattern of the degree of soil moisture saturation presented consistent values for the different uses and occupations of the soil, showing a great relation with the values of the evaporative fraction in all the images studied.

TOPOGRAPHIC ASPECTS IN THE SPATIAL AND TEMPORAL DYNAMIC OF NET RADIATION

ABSTRACT: The measurements obtained by remote sensing are influenced by issues related to relief. Based on that, this paper aims to analyze the spatial and temporal dynamics of the net radiation (Rn), considering the influence of topographic parameters on it, in Edgardia Experimental Farm (FEE). It was used the methodology based on the SEBAL algorithm (Surface Energy Balance Algorithm for Land) to estimate the net radiation by orbital images. In order to assess the topographic influence on the computing of net radiation, three methodologies were applied: without topographic correction (RnSem), cosine correction (RnCos) and C correction (RnC). These methodologies were applied on 21 images of the orbital platform Landsat-5/TM, from 1985 up to 2010. Due to the complex relief of the FEE, the cosine correction did not show effectiveness on the attenuation of topographic influence. For the values of RnC, we noticed an average reduction of 5.97% for the standard deviation, relative to the images without correction. These results show the importance of considering the relief, to achieve higher accuracies on the estimation of biophysical parameters with orbital images.

Estimativa do balanço de radiação por sensoriamento remoto de diferentes usos de solo no sudoeste da Amazônia brasileira

RESUMO Mudanças no uso do solo têm motivado pesquisas sobre a dinâmica de trocas radiativas e energéticas na Amazônia Brasileira que, por sua vez, geram demanda destas informações de superfície em escalas espaciais e temporais. Enquanto a medição destas trocas em torres micrometeorológicas fornece resultados pontuais, o sensoriamento remoto apresenta resultados acurados e de baixo custo para estimá-las em escala regional. Este estudo objetivou avaliar a distribuição espacial e temporal de estimativas de saldo de radiação e parâmetros biofísicos por sensoriamento remoto de diferentes usos do solo no sudoeste da Amazônia Brasileira. Foram selecionadas 04 áreas de solo coberto por floresta amazônica natural, floresta amazônica manejada, sistema silvipastoril e pastagem. O saldo de radiação, NDVI, índice de área foliar, albedo e temperatura radiométrica foram estimados pelo algoritmo SEBAL, usando imagens do sensor TM do satélite Landsat 5 em julho de 2009, 2010 e 2011. O NDVI, IAF, albedo e saldo de radiação apresentaram maiores valores na floresta natural, seguida por floresta manejada, sistema silvipastoril e pastagem. A temperatura radiométrica da superfície apresentou maiores valores para o sistema silvipastoril seguido por pastagem, floresta natural e floresta manejada.

Validation of the net radiation through sebal algorithm in different classes of land use and occupation in Rio de Janeiro

The aim of this study was (a) to assess and evaluate the net radiation (R n ) by SEBAL algorithm and (b) to assess the net radiation (R n ) by the landscape’s spatial temporal dynamic using ISODATA algorithm, in entire city of Rio de Janeiro. Has been calculated the R n by using the TM sensor images and orbital platform Landsat 5 and by Penman-Monteith method (FAO 56) with the conventional meteorological station data (EMC). The R n values obtained with the SEBAL algorithm to the EMC cut area were slightly smaller than those obtained by the Penman-Monteith method (FAO 56), with VM = -36 (Wm -2 ) and EPE = 84.44 Wm -2 . The R n obtained by SEBAL has a high correlation with the values obtained in the surface. The R n values obtained with the algorithm for the land use and occupation classes in the city of Rio de Janeiro were similar to those reported by other authors for the same classes.

Study of biophysical parameters using remote sensing techniques to Quixeré-CE region.

This work aims to analyze the behavior and the spatial variability of energy fluxes, albedo, surface temperature and vegetation index (NDVI) through the SEBAL algorithm, used in remote sensing for different surfaces in the region of Quixeré-EC. It was used TM- Landsat 5 satellite images for the dates October 24, 2005 and August 8, 2006, where the SEBAL algorithm was applied to calculate the fluxes of H, LE, Rn, G, and the surface albedo. From the clippings of a coverage area of banana orchard, savanna and bare soil, in order to check the H + LE and Rn-G components of energy balance. Correlations greater than 0.99 was observed between the components of energy balance H + LE and Rn-G, the relationship between surface albedo and radiation balance in the orchard area showed higher correlations to 0.88, the area comprised by savanna, for the day 297 showed no good correlation between variables, approximately 69% of unexplained variation in day 220 was about 0.88 correlation between the variables, this fact is associated homogeneous characteristics of the area that presented an increase of moisture available in relation to day 297.

Evaluation of SEBAL and SEBS Algorithms in the Estimation of Maize Evapotranspiration

Crop evapotranspiration (ET) is an important parameter for agricultural water management. This parameter can be estimated by multiplying of reference crop evapotranspiration (ETO) and crop coefficient. Usually ETO is calculated based on (daily) weather data at the weather stations. Considering the spatial variations of the weather parameters and subsequently of ET, application of the methods which can consider these variations are interested. Developed algorithms to estimate ET based on satellite images is one of those methods. The aim of the current study was to assess the accuracy of estimated ET based on SEBAL and SEBS algorithms using LANDSAT TM images in Mahidasht, Kermanshah province, Iran. For this purpose, the ET of maize was calculated using four images of LANDSAT during the maize growing season in year 2010. At the same time, the actual ET of maize was measured in a Lysimeter in the same region. Results indicating reasonable match between measured and calculated crop evapotranspiration by both algorithms. The maximum difference between the calculated evapotranspiration by SEBAL and SEBS algorithms with measured values by Lysimeter were about 9.79% and 4.56% of measured ET, respectively. Original Research Article Farhadi Bansouleh et al.; IJPSS, 6(6): 350-358, 2015; Article no.IJPSS.2015.125 351

Actual Evapotranspiration Estimation Using Remote Sensing: Comparison of SEBAL and SSEB Approaches

The main objective of this paper was to evaluate the daily actual evapotranspiration (ET) accuracy obtained by remote sensing algorithms when compared with Bowen ratio measurements performed in the cotton fields. The experiment was conducted in a cotton experimental field of EMBRAPA located in Ceara State, Brazil. Seven TM Landsat-5 images acquired in 2005 and 2008 were used to perform SEBAL and SSEB algorithms. The comparison between the estimated values by remoting sensing algorithms and the measured values in situ showed an acceptable accuracy. Besides, SSEB algorithm showed to be an important tool for ET analysis in the semi-arid regions, due to the fact that it does not need the meteorological data to solve the energy balance, but only the average temperature of the “hot” and “cold” pixels. Additionally, SSEB presents simpler processing than SEBAL algorithm that needs to solve an iterative process to obtain the sensible heat flux values.

Estimativa de componentes do balanço de radiação em diferentes tipos de uso e cobertura do solo

Estudos sobre o balanço de radiação em áreas de expansão agropecuária, especialmente em estados agroexportadores como Mato Grosso, são relevantes para a compreensão da interação atmosfera-biosfera. Este estudo estimou alguns componentes do balanço de radiação em áreas distintas (floresta secundária, reflorestamento com eucaliptos e cultivos agrícolas) no município de Lucas do Rio Verde/MT com base em magens do satélite Landsat 5 - TM. As imagens escolhidas foram de 20/01 e 26/04 do ano de 2010. As imagens foram processadas utilizando o algoritmo SEBAL para o cálculo dos valores do saldo de radiação instantâneo (Rn inst), albedo e NDVI. Os resultados evidenciaram alta variabilidade no Rn inst, albedo e NDVI tanto entre as distintas coberturas quanto para as diferentes datas. As áreas de floresta secundária e reflorestamento de eucaliptos apresentaram magnitudes similares, enquanto as áreas com cultivos agrícolas os valores apresentam relações intrínsecas referentes aos estádios de desenvolvimento com complexa interação radiativa.

ANALYSIS OF ENVIRONMENTAL PARAMETERS IN GILBUÉS – PI USING SATELLITE IMAGES

This paper aims to analyze the desertification process in the Gilbués region, southwestern portion of Piauí state, through remote sensing techniques with a perspective of verify whether there is a relationship of environmental parameters (surface albedo, NDVI, surface temperature, radiation and energy balances, as well as non-evaporative fraction) with the desertification process presented in this study area. We used images from the satellite Landsat 5-TM of August 19, 1994 and August 15, 2010 and applied the SEBAL and S-SEBI algorithms for obtaining environmental parameters analyzed. It was diagnosed cover removal of native vegetation, which may indicate areas undergoing to desertification and/or environmental degradation. Similarly, there was a reduction of surface net radiation, increased soil heat fluxes, reduction of energy used for evaporation and increases in the energy used for heating the soil and air, causing the temperature increase, and a systematic increase of the soil moisture deficit in the studied region.

Estimativa do balanço de energia utilizando imagens TM - Landsat 5 e o algoritmo SEBAL no litoral sul de Pernambuco

As trocas de energia na interface solo-planta-atmosfera, por meio das componentes do balanço de radiação (Rn) e dos fluxos de calor no solo (G), sensível (H) e latente (LE), são essenciais para a modelagem climática e hidrológica que, por sua vez, afetam toda a biosfera. Dessa forma, esta pesquisa teve por objetivos: (1) estimar e comparar o comportamento dos componentes do balanço de energia, usando o algoritmo SEBAL - Surface Energy Balance Algorithm for Land, em diferentes tipos de uso e cobertura do solo e (2) validar o algoritmo. Para isso, foram usadas três imagens TM - Landsat 5 de órbita e ponto 214/066, com datas de passagem em 26 de agosto de 2006, 6 de setembro de 2010 e 28 de janeiro de 2011, todas recortadas para enquadrar o litoral sul de Pernambuco. Os resultados mostraram a capacidade do SEBAL de estimar a variabilidade espacial dos diferentes componentes do balanço de energia, com capacidade de distinguir diferentes ocupações do solo. O cômputo do balanço de energia possibilita observar as formas diferenciadas do uso da energia pelos diferentes tipos de cobertura do solo e verificar aqueles que propiciam melhor conforto térmico. As estimativas da evapotranspiração obtidas pelo algoritmo SEBAL apresentaram uma boa concordância com os resultados obtidos pelo método da FAO-Penman-Monteith demonstrando, dessa forma, a potencialidade da abordagem metodológica escolhida.

Geotecnologias aplicadas à avaliação de parâmetros biofísicos do Pantanal

O objetivo deste trabalho foi avaliar parâmetros biofísicos de superfície do Bioma Pantanal com a aplicação de geotecnologias. Foram utilizados o algoritmo Sebal ("surface energy balance algorithm for land"), imagens do sensor Modis ("moderate‑resolution imaging spectroradiometer") e o mapa de classes de uso e cobertura da terra. Os resultados obtidos para NDVI, temperatura da superfície, albedo, fluxo de calor sensível diário, saldo de radiação diário e evapotranspiração real diária foram consistentes com dados de literatura para os diferentes usos e cobertura da terra, e corroboram a eficiência da capacidade analítica e sinóptica das estimativas do Sebal. Tais resultados mostram o potencial de geotecnologias na implementação de modelos ou algoritmos voltados para a compreensão da dinâmica de processos biofísicos de interação solo‑planta‑atmosfera do Pantanal.

A MODIS-Based Energy Balance to Estimate Evapotranspiration for Clear-Sky Days in Brazilian Tropical Savannas

Evapotranspiration (ET) plays an important role in global climate dynamics and in primary production of terrestrial ecosystems; it represents the mass and energy transfer from the land to atmosphere. Limitations to measuring ET at large scales using ground-based methods have motivated the development of satellite remote sensing techniques. The purpose of this work is to evaluate the accuracy of the SEBAL algorithm for estimating surface turbulent heat fluxes at regional scale, using 28 images from MODIS. SEBAL estimates are compared with eddy-covariance (EC) measurements and results from the hydrological model MGB-IPH. SEBAL instantaneous estimates of latent heat flux (LE) yielded r 2= 0.64 and r2 = 0.62 over sugarcane croplands and savannas when compared against in situ EC estimates. At the same sites, daily aggregated estimates of LE were r 2 = 0.76 and r2 = 0.66, respectively. Energy balance closure showed that turbulent fluxes over sugarcane croplands were underestimated by 7% and 9% over savannas. Average daily ET from SEBAL is in close agreement with estimates from the hydrological model for an overlay of 38,100 km2 (r2 = 0.88). Inputs to which the algorithm is most sensitive are vegetation index (NDVI), gradient of temperature (dT) to compute sensible heat flux (H) and net radiation (Rn). It was verified that SEBAL has a tendency to overestimate results both at local and regional scales probably because of low sensitivity to soil moisture and water stress. Nevertheless the results confirm the potential of the SEBAL algorithm, when used with MODIS images for estimating instantaneous LE and daily ET from large areas.