Shipborne single-photon fluorescence oceanic lidar: instrumentation and inversion.

Area of Science:

• Oceanography
• Remote Sensing
• Biophotonics

Background:

• Laser-induced fluorescence (LIF) is vital for remote sensing of aquatic phytoplankton.
• Challenges include weak signals, laser attenuation in water, and difficulty in simultaneously retrieving optical properties.

Purpose of the Study:

• To develop a novel all-fiber fluorescence oceanic lidar system.
• To enable simultaneous retrieval of attenuation coefficient and fluorescence volume scattering function.
• To improve subsurface phytoplankton profiling detection.

Main Methods:

• Utilized single-photon detection technology for subsurface fluorescence profiling.
• Applied the Klett inversion method adapted for fluorescence lidar.
• Conducted shipborne experiments for over 9 hours in offshore areas.

Main Results:

• Achieved accurate subsurface fluorescence profiles.
• Successfully retrieved the attenuation coefficient (Klidarmf) with <10% error.
• Retrieved the fluorescence volume scattering function at 180° (βf) with <20% error for chlorophyll concentrations from 0.01 to 10 mg/m³.
• Validated profiling detection capabilities through continuous shipborne experiments.

Conclusions:

• The novel all-fiber fluorescence oceanic lidar demonstrates significant potential for profiling aquatic phytoplankton.
• This technology supports the study of dynamic changes and environmental responses of subsurface phytoplankton populations.