Analysis of the Optimal Wavelength for Oceanographic Lidar at the Global Scale Based on the Inherent Optical Properties of Water

Shuguo Chen,Ge Chen,Junwu Tang,Cheng Xue,Lianbo Hu,Tinglu Zhang

doi:10.3390/rs11222705

Abstract

Understanding the optimal wavelength for detecting the water column profile from a light detection and ranging (lidar) system is important in the design of oceanographic lidar systems. In this research, the optimal wavelength for detecting the water column profile using a lidar system at the global scale was analyzed based on the inherent optical properties of water. In addition, assuming that the lidar system had a premium detection characteristic in its hardware design, the maximum detectable depth using the established optimal wavelength was analyzed and compared with the mixed layer depth measured by Argo data at the global scale. The conclusions drawn are as follows: first, the optimal wavelengths for the lidar system are between the blue and green bands. For the open ocean, the optimal wavelengths are between 420 and 510 nm, and for coastal waters, the optimal wavelengths are between 520 and 580 nm. To obtain the best detection ability using a lidar system, the best configuration is to use a lidar system with multiple bands. In addition, a 490 nm wavelength is recommended when an oceanographic lidar system is used at the global scale with a single wavelength. Second, for the recommended 490 nm band, a lidar system with the 4 attenuating length detection ability can penetrate the mixed layer for 80% of global waters.

Highlights

Vertical profiles of oceanic water data, such as chlorophyll profiles and temperature and salinity profiles, which determine the upper mixed layer depth, play important roles in understanding oceanic physical–biogeochemical processes, ocean–atmosphere interactions, and ocean primary production [1,2,3]
In this research, the optimal wavelength for detecting global-scale characteristics of the water column profile using a lidar system was determined based on the inherent optical properties of water
Assuming that the lidar system has optimal detection characteristics in its hardware design, the maximum detectable depth using the established optimal wavelength was analyzed and compared with the mixed layer depth measured by Argo data at the global scale

Summary

Introduction

Vertical profiles of oceanic water data, such as chlorophyll profiles and temperature and salinity profiles, which determine the upper mixed layer depth, play important roles in understanding oceanic physical–biogeochemical processes, ocean–atmosphere interactions, and ocean primary production [1,2,3]. Various platforms have been used to obtain vertical profiles, including buoys, subsurface buoys, Argo, Bio-Argo, and autonomous climbing systems that use ropes, gliders, AUVs, etc. These platforms can only be used to obtain data from a small region. Light detection and ranging (lidar) systems are the only systems that have the ability to obtain depth-resolved profile information. These systems can be deployed from airborne or space-borne platforms and can provide an additional fast and non-expensive survey of vast areas of ocean

Methods

Results

Conclusion