Question

Provide the rationale for the use of thermal remote sensing in water pollution detection.

Present the advantage of Forward-Looking Infrared (FLIR) systems.

  

Why can SAR imagery be used for the detection of oil spill in the sea surface?

Provide the rationale for SAR imagery be used in the estimation of sea surface salinity.

Answer 1

Thermal remote sensing is a important tool for monitoring freshwater systems to detect thermal changes affecting biological productivity. It allows the development of management plans to reduce the effect of man-made thermal releases.

During the war,they have three distinct advantages over other imaging technologies.The imager itself detects energy emitted from the target rather than sending out energy that is reflected from the target.

SAR is useful particularly for searching large areas and observing oceans at night and at cloudy weather conditions .The brightness of the

captured image is a reflection of the properties of the target-surface. The possibility of detecting an oil spill in a SAR image relies on the fact that the

oil film decreases the backscattering of the sea surface resulting in a dark formation that contrasts with the brightness of the surrounding spill-free sea. The presence of oil film on the sea surface damps the small waves and drastically reduces the measured backscatter energy, resulting in darker areas in SAR imagery.

It has become a real key in coastal area remote sensing. The tool we are working with is a P-band airborne synthetic aperture radar (SAR) called RAMSES made by the ONERA (Paillou et al., 2001). It is a multiband frequency radar which works for all four-polarizations. The active P-band challenge is that such an airborne radar has never been experimented before this day for the study of salinity. This is particularly surprising because of its rising sensibility with salinity gradient.