Oceanographic lidar attenuation coefficients and signal fluctuations measured from a ship in the Southern California Bight

Abstract

We measured the attenuation coefficient of the National Oceanic and Atmospheric Administration lidar from a ship in the Southern California Bight in September 1995. The region from approximately 5 to 30 m in depth was covered. The laser was linearly polarized, and the receiver was operated with the same polarization and the orthogonal polarization. The measured values were between 0.08 and 0.12 m(-1) and were highly correlated with in situ measurements of the beam attenuation coefficient. Fluctuations of the lidar signal were found to be induced primarily by surface waves whose wavelengths are approximately three times the lidar spot size at the surface.

Three-Dimensional Mapping of Fluorescent Dye Using a Scanning, Depth-Resolving Airborne Lidar

“…Each profile was fit to a single exponential, and the resulting slope estimates were averaged to give k 532 ϭ 0.085 Ϯ 0.003. We note in passing that this value is close to lidar attenuation coefficients reported by Churnside et al (1998) in relatively clear water in the Southern California Bight.…”

“…Similarly, k S can be written as the sum k S ϭ k 532 ϩ k 580 . We estimate k 532 from the measured backscatter profiles at that frequency (Churnside et al 1998). A representative sample of 2500 profiles outside the dye patch are shown in Fig.…”

“…As discussed by Gordon (1982), Phillips and Koerber (1984), and Churnside et al (1998), the attenuation coefficient in (3) is phenomenological, and its relation to such properties as the beam attenuation coefficient c or the diffuse attenuation coefficient K d depends on the amount of multiple scattering. Unfortunately, we do not have the requisite hydro-optical measurements to estimate this reliably.…”

“…These systems have been shown to be very effective for their intended uses: bathymetric surveys (e.g., Irish and Lillycrop 1999), chlorophyll mapping (e.g., Hoge and Swift 1983;Yoder et al 1993), and fish stock assessment (e.g., Squire and Krumboltz 1981;Churnside et al 1997). Despite efforts in these other areas, however, there have been few studies using lidar in conjunction with the fluorescent dye releases to study small-scale mixing in the ocean.…”

Dual-polarization airborne lidar for freshwater fisheries management and research

“…1 Multiple airborne bathymetric lidar systems have been developed for looking into seawater, primarily for profiling the seafloor surface and, sometimes, also for measuring the optical properties of the water column. [2][3][4][5][6][7][8] Lidars also have been developed for airborne or shipborne measurements of water clarity and attenuation, [9][10][11] spatial and temporal variations in oceanic scattering layers and plankton distributions, [12][13][14] internal waves, 15 chlorophyll content, [16][17][18] and fish. 19 Recently, a space-based lidar was used for producing global maps of phytoplankton biomass and total particulate organic carbon.…”