Lidar and Ocean Color Remote Sensing for Marine Ecology

The launch of the Coastal Zone Color Scanner (CZCS, 1978-1986) marked a new area of ocean color remote sensing. Since then, with the extraordinary global data acquisition capabilities and daily to inter-annual observations, ocean color remote sensing has reshaped our understanding of upper-ocean biogeochemistry at global ocean scales and in regional basins. Over the last several decades, lidar remote sensing has provided an increasingly detailed view of aerosols and clouds. However, previous ocean color observations have heavily relied on passive remote sensing techniques, which are limited to the upper part of the water and cannot provide the underlying vertical structure information. Moreover, due to the demand for sunlight, passive remote sensing can only perform during the daytime, which results in the inability to sample high-latitude ocean areas during polar nights, where only a small amount of data is available. Recently, the light detection and ranging (lidar) active remote sensing technique has aroused widespread attention because of its depth-resolving ability and independence from sunlight, which could address the limitations mentioned above. Lidar is a highly reliable tool that can measure several optical and physical parameters of seawater for marine environment investigation. In practice, shipborne, airborne, and spaceborne lidars have been widely employed in oceanographic studies such as bathymetry surveys, optical profiling, polar plankton variations, animal diel migration, plankton layer detection, etc. Fluorescence lidar detects the emission of a variety of naturally occurring molecules, such as chlorophylls, carotenoids, phycobilins, or other photosynthetic pigments, when excited by a laser. In aquatic settings, this allows for the detection of toxic red tide events or increased concentrations of algae and cyanobacteria, which could indicate hypoxia. Fluorescence LIDAR is also used in atmospheric research to study complex organic aerosols, airborne pathogens, and atmospheric gases. With new vertically resolved and diurnal continuous measurements, lidar can provide new insights into seawater and an atmospheric bio-optical vertical structure, which will enhance our understanding of marine and atmosphere ecosystems and biogeochemical processes.

This Research Topic aims to bring some of the leading scholars in the fields of lidar remote sensing, ocean optics, atmospheric optics, and marine and atmosphere biochemists to describe current and new lidar remote sensing technologies (in-situ, ship-based, airborne, and satellite), and collect the recent achievements of active and passive optical remote sensing in ocean and atmosphere in recent years.

This Research Topic welcomes:
• History or review of the ocean or atmosphere lidar remote sensing;
• Ocean optics;
• Lidar remote sensing of the ocean;
• Atmospheric optical properties;
• Atmospheric lidar remote sensing technology;
• Fluorescence lidar remote sensing technology;
• Feature extraction and pattern recognition technique in laser-induced fluorescence spectra;
• Lidar remote sensing of the environment;
• Development of new algorithms of lidar remote sensing;
• Evaluation of oceanographic lidar inversion algorithms;
• Active applications with synergies to passive remote sensors and/or in-situ measurements from ships or Bio-Argo profilers;
• Potential of space-borne lidar for bathymetry or ocean interior biology;
• Ground-based, ship-based, airborne, and space-borne lidar (CALIPO, ICEsat2, etc.).