Abstract
Ocean water column information profiles are essential for ocean research. Currently, water column profiles are typically obtained by ocean lidar instruments, including spaceborne, airborne and shipborne lidar, most of which are equipped with a 532 nm laser; however, blue wavelength penetrates more for open ocean detection. In this paper, we present a novel airborne dual-wavelength ocean lidar (DWOL), equipped with a 532 and 486 nm laser that can operate simultaneously. This instrument was designed to compare the performance of 486 and 532 nm lasers in a single detection area and to provide a reference for future spaceborne oceanic lidar (SBOL) design. Airborne and shipborne experiments were conducted in the South China Sea. Results show that—for a 500-frame accumulation—the 486 nm channel obtained volume profiles from a depth of approximately 100 m. In contrast, the vertical profiles obtained by the 532 nm channel only reached in a depth of 75 m, which was approximately 25% less than that of 486 m channel in the same detection area. Results from the inverse lidar attenuation coefficient α(z) for the DWOL show that the maximum value of α(z) ranged from 40 to 80 m, which was consistent with the chlorophyll-scattering layer (CSL) distribution measured by the shipborne instrument. Additionally, α486(z) decreased for depth beyond 80 m, indicating that the 486 nm laser can potentially penetrate the entire CSL.
Highlights
Over the past decades, both passive and active ocean optical remote sensing technologies have revolutionized our understanding of the ocean
The signal-to-noise ratio (SNR) of the airborne experiment results is taken as a criterion to
The signal-to-noise ratio (SNR) of the airborne experiment results is taken as a criterion to estimate the effectiveness of the airborne experiment results
Summary
Both passive and active ocean optical remote sensing technologies have revolutionized our understanding of the ocean. Passive remote sensing technology is commonly used in the research of the carbon cycle for the upper ocean on a global scale [1,2] This type of system can only obtain weighted integral information at a limited depth. Vertical profile information such as chlorophyll profiles or salinity data, is very important for understanding oceanic physical-biogeochemical processes, ocean primary production and other aspects of the ocean environment [3,4,5] This type of information can be obtained via active ocean remote sensing technology, such as shipborne and airborne ocean lidar for small-region detection and spaceborne ocean lidar (SBOL) for large-scale detection [6,7]. The comparison between the airborne and the shipborne will be discussed
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