Observation of submarine sand waves using ASTER stereo sun glitter imagery

Abstract

Signatures of sun glitter images strongly depend on the viewing angle. Stereo observation can provide more valuable information than observation from one angle. In this work, the sun glitter patterns caused by submarine sand waves were studied using stereo images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which operates a high spatial resolution (15 m) optical and near-infrared sensor on board the Terra satellite. The previous imaging geometrical model has been improved, and the difference in the viewing angle among pixels is considered. We found that brightness reversal occurs in some stereo imagery of submarine sand waves. Based on the imaging geometry model, an interaction model of current topography, and a sun glitter radiance transfer model, a simulation model was developed for sun glitter from submarine sand waves at multiple viewing angles. The cases of nadir-looking and backward-looking were simulated with the model. The results show the following differences between the two viewing angles, which have also been observed in the ASTER images. Both tendency and extent of the simulated radiance are in good agreement with those in actual images. In the nadir-looking view, obvious differences have been observed between the normalized significant radiance from smooth and rough facets. This difference increases with increasing viewing angle, to a peak, and then decreases. However, in most cases, the difference in the back view is smaller and shows an opposite tendency regarding the viewing angle from the nadir-looking view. Thus, the sand-wave characteristics in the nadir-looking images seem to be more enhanced than that in the backward-looking images.

Acknowledgements

The authors acknowledge the cooperative efforts between NASA and Japan’s Ministry of Economy Trade and Industry (METI) for developing the ASTER sensor. The stereo optical images used in this study were provided by the Centre for Earth Observation and Digital Earth (CEODE), Chinese Academy of Sciences (CAS), China. The authors thank the NOAA for providing NCEP reanalysis data and Editage for English language editing.

Additional information

Funding

This research was supported by the National Nature Science Foundation of China [grant numbers 40706062 and 91128204], the Public Science and Technology Research Fund Project of Surveying, Mapping and Geoinformation [grant number 201512030], and the Public Science and Technology Research Fund Project of Ocean [grant number 201105001].