Determination of immersion factors for radiance sensors in marine and inland waters: a semi-analytical approach using refractive index approximation

Pravin Jeba Dev; P. Shanmugam

doi:10.1117/12.2223711

7 May 2016 Determination of immersion factors for radiance sensors in marine and inland waters: a semi-analytical approach using refractive index approximation

Pravin Jeba Dev, P. Shanmugam

Author Affiliations +

Proceedings Volume 9878, Remote Sensing of the Oceans and Inland Waters: Techniques, Applications, and Challenges; 987803 (2016) https://doi.org/10.1117/12.2223711
Event: SPIE Asia-Pacific Remote Sensing, 2016, New Delhi, India

Abstract

Underwater radiometers are generally calibrated in air using a standard source. The immersion factors are required for these radiometers to account for the change in the in-water measurements with respect to in-air due to the different refractive index of the medium. The immersion factors previously determined for RAMSES series of commercial radiometers manufactured by TriOS are applicable to clear oceanic waters. In typical inland and turbid productive coastal waters, these experimentally determined immersion factors yield significantly large errors in water-leaving radiances (L_w) and hence remote sensing reflectances (R_rs). To overcome this limitation, a semi-analytical method with based on the refractive index approximation is proposed in this study, with the aim of obtaining reliable L_w and R_rs from RAMSES radiometers for turbid and productive waters within coastal and inland water environments. We also briefly show the variation of pure water immersion factors (I_fw) and newly derived If on L_w and R_rs for clear and turbid waters. The remnant problems other than the immersion factor coefficients such as transmission, air-water and water-air Fresnel’s reflectances are also discussed.

Citation Download Citation

Pravin Jeba Dev and P. Shanmugam "Determination of immersion factors for radiance sensors in marine and inland waters: a semi-analytical approach using refractive index approximation", Proc. SPIE 9878, Remote Sensing of the Oceans and Inland Waters: Techniques, Applications, and Challenges, 987803 (7 May 2016); https://doi.org/10.1117/12.2223711

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