6533b7cefe1ef96bd1256f12

RESEARCH PRODUCT

Measurement and correction of atmospheric effects in O<inf>2</inf>-B and O<inf>2</inf>-A absorption bands in the context of sun-induced fluorescence remote sensing

subject

description

Under sun-light illumination, the shape of the atmospheric oxygen bands (O 2 -B, 687 nm and O 2 -A, 760 nm) of the vegetation radiance is modified by chlorophyll fluorescence. However for far-range measurements, atmospheric effects also modify this shape. In this study, measurements in O 2 -A and O 2 -B absorption bands have been performed at different altitudes up to 3123 m over bare soil and wheat fields. It is observed that bands depth increase significantly with altitude. In O 2 -B band, the total magnitude of variation is of the same order of magnitude as the change induced by vegetation fluorescence, while it is much greater in O 2 -A band. We used MODTRAN 4 to correct measurements from these atmospheric effects and to retrieve ground level band depths. It is found that the variation of corrected band depth with altitude is greatly reduced. These results show that MODTRAN 4 can be used to account for atmospheric effects. We also showed that an accurate evaluation of the contribution of environment is needed to correct band depth from atmospheric effects, especially in the O 2 -B band.