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Characterization and Modeling of Profiling Oceanographic Lidar for Remotely Sampling Ocean Optical Properties
Title
Characterization and Modeling of Profiling Oceanographic Lidar for Remotely Sampling Ocean Optical Properties.
Creator
Strait, Christopher, Nayak, Aditya, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
Lidar has the ability to supplant or compliment many current measurement technologies in ocean optics. Lidar measures Inherent Optical Properties over long distances without impacting the orientation and assemblages of particles it measures, unlike many systems today which require pumps and flow cells. As an active sensing technology, it has the benefit of being independent of time of day and weather. Techniques to interpret oceanographic lidar lags behind atmospheric lidar inversion...
Show moreLidar has the ability to supplant or compliment many current measurement technologies in ocean optics. Lidar measures Inherent Optical Properties over long distances without impacting the orientation and assemblages of particles it measures, unlike many systems today which require pumps and flow cells. As an active sensing technology, it has the benefit of being independent of time of day and weather. Techniques to interpret oceanographic lidar lags behind atmospheric lidar inversion techniques to measure optical properties due to the complexity and variability of the ocean. Unlike in the atmosphere, two unknowns in the lidar equation backscattering at 180o (𝛽𝜋) and attenuation (c) do not necessarily covary. A lidar system developed at the Harbor Branch Oceanographic Institute is used as a test bed to validate a Monte-Carlo model to investigate the inversion of optical properties from lidar signals. Controlled tank experiments and field measurements are used to generate lidar waveforms and provide optical situations to model. The Metron EODES backscatter model is used to model waveforms. A chlorophyll based forward optical model provides a set of 1500 unique optical situations which are modeled to test inversion techniques and lidar geometries. Due to issues with the lidar system and model the goal of validating the model as well as a more mature inversion experiment were not completed. However, the results are valuable to show the complexity and promise of lidar systems.
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013631
Subject Headings
Lidar, Remote sensing, Seawater--Optical properties
Format
Document (PDF)
POST PROCESSING METHODS FOR THREE DIMENSIONAL IMAGING LIDAR WITH MULTI-SCALE CHARACTERIZATION OF SUBSEA ORGANISMS
Title
POST PROCESSING METHODS FOR THREE DIMENSIONAL IMAGING LIDAR WITH MULTI-SCALE CHARACTERIZATION OF SUBSEA ORGANISMS.
Creator
McKenzie, Trevor Lee, Nayak, Aditya, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
The thesis objective is to develop protocols that provide analysis and interpretation for data from a pulsed laser serial scanning lidar system for underwater imaging. The specific focus is remotely observing marine organisms in the centimeter size range in the poorly understood mesopelagic realm of the ocean. The Unobtrusive Multi-Static Lidar Imager (UMSLI) system captures an expansive volume scan field with differentiating imaging resolution per planar slice, allowing precise assignment of...
Show moreThe thesis objective is to develop protocols that provide analysis and interpretation for data from a pulsed laser serial scanning lidar system for underwater imaging. The specific focus is remotely observing marine organisms in the centimeter size range in the poorly understood mesopelagic realm of the ocean. The Unobtrusive Multi-Static Lidar Imager (UMSLI) system captures an expansive volume scan field with differentiating imaging resolution per planar slice, allowing precise assignment of location for organisms in the field of view. The multi-static highly collimated beams are recorded by a photo-multiplier tube receiver as a time lapse waveform of the returned energy flux, each waveform comprehensibly represents an image pixel in spatially and temporally. Complied lidar waveforms produce an array of returns which signify the magnitude of backscatter from varying sized particles across the observed volume. These volume scans are uniquely evaluated and transformed for each time bin through a processing method which extracts particle characteristics and statistics based on adaptive spatial and temporal techniques. The post processing method aims to greatly extend the capabilities of the lidar imaging system to extract particles. Results of the processing method are presented as particle counts and particle size distributions of the water columns during observed vertical migration periods. Methods are compared with other optical devices for validation, and results are interpreted to better understand the organism distribution in the mesopelagic and their behavior, with respect to diel vertical migrations.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013396
Subject Headings
Underwater imaging systems, Three-dimensional imaging--Methodology, Optical radar, Vertical distribution (Aquatic biology)
Format
Document (PDF)
APPLICATIONS OF DIGITAL HOLOGRAPHIC IMAGING TOWARDS CHARACTERIZATION OF MARINE PLANKTON DISTRIBUTIONS AND BIOPHYSICAL INTERACTIONS
Title
APPLICATIONS OF DIGITAL HOLOGRAPHIC IMAGING TOWARDS CHARACTERIZATION OF MARINE PLANKTON DISTRIBUTIONS AND BIOPHYSICAL INTERACTIONS.
Creator
Barua, Ranjoy, Nayak, Aditya R., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
Characterization of the distribution and biophysical interactions of oceanic planktonic organisms is crucial to address fundamental science questions associated with climate change, marine ecology, pollution, and ocean optics. Thus, development of instrumentation techniques for monitoring plankton at high spatial and temporal resolutions is important. This dissertation deals with the advancements made in applying digital holography – a 3-D non-intrusive, freestream imaging technique – to...
Show moreCharacterization of the distribution and biophysical interactions of oceanic planktonic organisms is crucial to address fundamental science questions associated with climate change, marine ecology, pollution, and ocean optics. Thus, development of instrumentation techniques for monitoring plankton at high spatial and temporal resolutions is important. This dissertation deals with the advancements made in applying digital holography – a 3-D non-intrusive, freestream imaging technique – to address three different applications associated with marine plankton monitoring and ecology. In the first project, an autonomous in-line digital holographic microscope was successfully deployed for rapid in situ detection of the harmful dinoflagellate, Karenia brevis in the coastal Gulf of Mexico. Monitoring K. brevis abundance and distribution are crucial for early warning systems and implementing preventative measures to limit potential damage. The holographic system was successfully paired with a convolutional neural network for automated data processing to ensure rapid and accurate K. brevis detection.
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Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00014096
Subject Headings
Marine plankton, Holography, Digital holographic microscopy
Format
Document (PDF)