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11.
An optical method is developed to estimate water transparency (or underwater visibility) in terms of Secchi depth (Z sd ), which follows the remote sensing and contrast transmittance theory. The major factors governing the variation in Z sd , namely, turbidity and length attenuation coefficient (1/(c + K d ), c = beam attenuation coefficient; K d = diffuse attenuation coefficient at 531 nm), are obtained based on band rationing techniques. It was found that the band ratio of remote sensing reflectance (expressed as (R rs (443) + R rs (490))/(R rs (555) + R rs (670)) contains essential information about the water column optical properties and thereby positively correlates to turbidity. The beam attenuation coefficient (c) at 531 nm is obtained by a linear relationship with turbidity. To derive the vertical diffuse attenuation coefficient (K d ) at 531 nm, K d (490) is estimated as a function of reflectance ratio (R rs (670)/R rs (490)), which provides the bio-optical link between chlorophyll concentration and K d (531). The present algorithm was applied to MODIS-Aqua images, and the results were evaluated by matchup comparisons between the remotely estimated Z sd and in situ Z sd in coastal waters off Point Calimere and its adjoining regions on the southeast coast of India. The results showed the pattern of increasing Z sd from shallow turbid waters to deep clear waters. The statistical evaluation of the results showed that the percent mean relative error between the MODIS-Aqua-derived Z sd and in situ Z sd values was within ±25%. A close agreement achieved in spatial contours of MODIS-Aqua-derived Z sd and in situ Z sd for the month of January 2014 and August 2013 promises the model capability to yield accurate estimates of Z sd in coastal, estuarine, and inland waters. The spatial contours have been included to provide the best data visualization of the measured, modeled (in situ), and satellite-derived Z sd products. The modeled and satellite-derived Z sd values were compared with measurement data which yielded RMSE = 0.079, MRE = ?0.016, and R 2 = 0.95 for the modeled Z sd and RMSE = 0.075, MRE = 0.020, and R 2 = 0.95 for the satellite-derived Z sd products. 相似文献
12.
Divyalakshmi Palanisamy Murugan Devaraj Sivarajan Meenatchisundaram Sivasamy Arumugam Saravanan Palanivel Rai Chockalingam Lajapathi 《Journal of Material Cycles and Waste Management》2018,20(1):481-488
Journal of Material Cycles and Waste Management - Anaerobic digestion studies were carried out with tannery excess secondary sludge obtained from common effluent treatment plant. The excess sludge... 相似文献
13.
Cao Rong-An Ma Nan Palanisamy Subramanian Talapphet Natchanok Zhang JiaMiao Wang ChangYuan You SangGuan 《Journal of Polymers and the Environment》2022,30(6):2291-2303
Journal of Polymers and the Environment - Non-starch polysaccharides derived from natural resources play a significant role in the field of food science and human health due to their extensive... 相似文献