Efeitos da correcao atmosferica em imagens multiespectrais orbitais para estudos em corpos d'agua interiores/Analysis of the effects of atmospheric correction on orbital images for studies in interior water bodies

• Published in: Ra'e ga Vol. 58; p. 39
• Main Authors: Segedi, Gabriella C, Cicerelli, Rejane E, de Almeida, Tati, Roig, Henrique Llacer, Olivetti, Diogo, Bernardi, Vicente, Castreghini, Adriana
• Format: Journal Article
• Language: English
• Published: Editora da UFPR 01-09-2023
• Subjects: Brasil
• ISSN: 1516-4136
• DOI: 10.5380/raega.v58i0.93465

The water reservoirs, in addition to their significance in electricity generation, serve as vital resources for various other requirements of the population. Images from orbital sensors have been applied to complement the monitoring of these environments and thus overcome the deficiency of spatial and temporal coverage of traditional techniques. However, studies involving water quality are still a great challenge due to the low signal coming from the water body and the interference of external factors (or environmental factors). Image correction/improvement procedures are often proposed, mainly to reduce atmospheric interference. In this study the best available atmospheric correction techniques were evaluated in order to indicate the technique that most closely matches the spectral response of remotely sensed images obtained in the field. During the study six atmospheric correction algorithms were applied (FLAASH, Second simulation of a Satellite Signal in the Solar Spectrum (6S), L8SR, Aquatic Reflectance (NASA/USGS), ACOLITE and Sen2Cor) that, based on the statistical analysis of discriminant analysis and covariance, indicated the 6S for Landsat and Sentinel images and ACOLITE for Landsat images as the most accurate. Although 6S showed a response close to the reference data, low variability in spectral response was observed. For time series, ACOLITE showed better capacity to correct the data. The type of application is also a preponderant factor, since it was evident that the use of time series indicated a different atmospheric correction technique when compared to the analysis of the scenes individually. Keywords: Inland water bodies; Atmospheric correction; Landsat-8; Sentinel-2. Os reservatorios hidricos alem de serem importantes para a producao de energia eletrica, sao recursos para outras necessidades da populacao. Imagens de sensores orbitais sao aplicadas para complementar o monitoramento desses ambientes e assim suprir a deficiencia de cobertura espacial e temporal das tecnicas tradicionais. No entanto, estudos envolvendo analises de qualidade de agua ainda sao um grande desafio devido ao baixo sinal proveniente do corpo d'agua e a interferencia de fatores externos (ou fatores ambientais). Procedimentos de correcao das imagens sao propostos com frequencia, principalmente para a reducao da interferencia atmosferica. Nesse estudo foram avaliadas as melhores tecnicas de correcao atmosferica disponiveis no intuito de indicar aquela tecnica que mais se aproxima da resposta espectral de sensoriamento remoto obtida em campo. No decorrer do estudo foram aplicados seis algoritmos de correcao atmosferica (FLAASH, Second simulation of a Satellite Signal in the Solar Spectrum (6S), L8SR, Aquatic Reflectance (NASA/ USGS), ACOLITE e Sen2Cor) que, a partir das analises estatisticas de analise discriminante e covariancia apontaram os aplicativos 6S para imagens Landsat e Sentinel e o ACOLITE para imagens Landsat como os mais acurados. Embora o 6S tenha apresentado resposta proxima dos dados de referencia, observou-se baixa variabilidade na resposta espectral. Para series temporais, o ACOLITE apresentou maior capacidade de correcao dos dados. O tipo de aplicacao tambem e um fator preponderante, pois ficou evidente que o uso de series temporais indicou uma tecnica de correcao atmosferica diferente quando comparado com a analise das cenas de forma individual. Palavras-chave: Corpos d'agua interiors, Correcao Atmosferica, Landsat-8, Sentinel-2.