Marine Optics and Ocean Color Remote Sensing

Abstract

Light plays an important role in aquatic ecosystems, both marine and freshwater. Penetration of light underwater influences various biogeochemical processes and also influences activities and behavioral patterns of marine organisms. In addition, dissolved and particulate water constituents present in the water column absorb and scatter light, giving water its characteristic color. The concentration or abundance of these constituents, referred to as optically active constituents (OACs) also determine light availability underwater. Thus color being an indicator of water column content, serves as a water quality parameter. Monitoring of the ocean color variables, such as the OAC concentrations and their optical properties, therefore, allows assessment of the health of an ecosystem. Advances in optical methodologies have improved the understanding of our ecosystems through multispectral and hyperspectral in situ measurements and observations. However, the ocean environment is vast and dynamic and so limitations of spatial and temporal coverage have been overcome with satellite remote sensing that provides oceanographers with repeated synoptic coverage. Being recognized as an essential climate variable (ECV) ocean color is monitored as part of the climate change initiative (CCI) of the European Space Agency (ESA). This chapter aims to provide the reader with an overview of the science of ocean color, introducing involved common terminologies and concepts and its global coverage using satellite remote sensing.

Saving the planet with appropriate biotechnology: 3. The high seas solution

“…Due to the aggressiveness of ultraviolet radiation from the sun in the upper sea layers, and also the constant adaptation of the controlled buoyancy of the phytoplankton, the optimal wavelength for marine algal photosynthetic activity is within the blue range of the spectrum, because this has the highest water penetration coefficient ( Fig. 7) (Mascarenhas & Keck, 2018). Luckily, thanks to today's LED technology, we are able to produce exactly the blue light that is needed, with acceptable levels of energy demand (Fig.…”

Optimization of Landsat Chl-a Retrieval Algorithms in Freshwater Lakes through Classification of Optical Water Types

“…The best performing algorithms in both OWTs typically used B and G bands, with the best performing algorithms in OWT-B h also commonly including the N band. Both OWTs returned algorithms using a B-G ratio, which is commonly used for oligotrophic waters due to increased water column penetration, lack of non-algal particles increasing scatter, and highest ρλ in the G band [88]. It is possible that the influence of non-algal particles in OWT-B h was driving the observed r 2 .…”

Hypothetical Product Generation of Geostationary Ocean Color Imager Bands Over the Yellow Sea and Bohai Sea Using Deep Learning Technique

“…Generally, instruments used for ocean color measurement are designed to be utilized primarily within the optical spectrum in the visible (VIS) and near infrared (NIR) range of 0.38 to 0.8 μm, which is similar to the 0.4 to 0.7 μm observed by the human eye, ranging from violet to red [20]. The VIS band is used to observe light that has been reflected from the Earth's surface and from clouds.…”

“…The first ocean color satellite; the Coastal Zone Color Scanner (CZCS) onboard the NIMBUS-7, was launched in 1978 [21] and operated from 1978 to 1987 [20]. Other ocean color sensors [22][23][24][25] include the Moderate-resolution Imaging Spectroradio-meter (MODIS) onboard the Aqua and Terra satellites, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) onboard the Seastar satellite, the Mediumresolution Imaging Spectrometer (MERlS) onboard the Environmental Satellite Envisat satellite, and the Ocean and Land Color Imager (OLCI) onboard the Sentinel-3, which continues the heritage of MERIS with six additional bands [26].…”