Análise comparativa do fator de reflectância adquirido em campo e por dados orbitais para um lago rico em fitoplâncton

Remote Sensing data is primarily derived from radiometric measurements, which can be taken in situ or by sensors on board of satellites. From radiometric measurements and considering the observation and illumination geometry some biophysical properties of the target can be inferred. In situ radiance values measured with an spectroradiometer, that is a hiperspectral sensor, are different from the orbital sensors that have a poor spectral and spatial resolution. This study aims to compare the spectroradiometer water spectral curve with the simulated curve that would be obtained by MODIS and OLI sensors in a chlorophyll rich lake. In situ radiance was measured at the main lake of the Aeronautics Technological Center (ATC), in São José dos Campos, São Paulo - Brazil. Besides the lake measurements, radiance of a lambertian reference plate was measured in order to calculate the reflectance factor. The spectral curve found for the in situ measurements were then used to estimate the corresponding curves obtained from MODIS and OLI sensors. When comparing the in situ spectral curve with those of the orbital sensors it is possible to notice that some key features are not detected by the later, due to the coarser spectral resolution of the bands and, also, because some wavelengths are not contemplated by the sensors simulated in this work. The best orbital sensor simulated was MODIS to this study besides its spatial resolution.