Space Coast Florida waters consist of shallow coastal turbid water along the southeastern United States and Florida’s east coast estuaries and tidal lagoon systems. The waters have become dominated by a bottom boundary sediment layer characterized by moving fluid mud near the bottom. Surface winds and their resulting water surface gravity waves result in the resuspension of the mud bottom boundary layer sediments and result in water columns with very low light visibility. The decreased light penetration as a function of depth and wavelength influences marine life that require light to function. The complex physical phenomena and associated underwater light fields can best be understand using Monte-Carlo models. Model results can be tuned to be applicable to specific satellites and channels for development of algorithms which make use of reflectance signatures measured by satellites as well as in-situ sensors. Recent model developments and model simulations are described with reference to WorldVeiw-3 satellite imagery and shape factors.
A non-homogeneous water column Monte Carlo model is utilized for predicting underwater light fields in shallow estuarine waters with suspended muds/flocs and a bottom lutocline boundary layer. This previously developed model creates synthetic water wave surfaces. Outputs are presented to demonstrate the response to water wave facet slopes at the surface and a lutocline bottom fluid mud boundary layer. Synthetic reflectance spectrums and radiometric quantities are modeled with different solar and sensor zenith and azimuth angles. Measurements in Space Coast Florida waters are used as model inputs. Averaged depth dependent concentration profiles for particulate matter suspended from the bottom fluid mud and lutocline layers are estimated from sondes. In this report vertical profiles of shape factors with various water surface slopes and fluid mud assumptions are shown. Model results suggests that suspended muds in the water column will have unique higher absorption influences upon the photosynthetically active light region of the underwater light field.
Two flow irradiance model solutions are tested using various bottom depths and hyperspectral in-situ bottom reflectance signatures for Elkhorn Coral, Bleached Reef, Sand, Sand and Seagrass, and Turtle Grass. Bottom reflectance signatures are used to simulate a water surface reflectance signatures from analytical solutions that can account for the effect of a collimated irradiance signal or direct sunlight within the water column. Simulated reflectance signatures are generated as a function of depth and wavelength in an optically clear water column and a turbid estuarine water column containing concentrations of chlorophyll-a, seston, and dissolved organic material. Simulated surface reflectance signatures as a function of water depth are then used to predict bottom reflectance signatures. Comparison of in-situ bottom reflectance signatures to simulated bottom reflectance signatures predicts model depth sensitivity at a 95% confidence level. Spectral window solutions for water column depths are detected for bottom types and estuarine type water column concentrations. Model can be coupled with bathymetry and high resolution water surface sensor derived reflectance signatures to monitor or map bottom variations for surveillance, environmental monitoring, fishing, or dredging applications in coastal waters or very shallow estuarine waters.
Hyperspectral signatures and imagery collected during the spring and summer of 2017 and 2016 are presented. Ground
sampling distances (GSD) and pixel sizes were sampled from just over a meter to less than 4.0 mm. A pushbroom
hyperspectral imager was used to calculate bidirectional reflectance factor (BRF) signatures. Hyperspectral signatures of
different water types and bottom habitats such as submerged seagrasses, drift algae and algal bloom waters were scanned
using a high spectral and digital resolution solid state spectrograph. WorldView-3 satellite imagery with minimal water
wave sun glint effects was used to demonstrate the ability to detect bottom features using a derivative reflectance
spectroscopy approach with the 1.3 m GSD multispectral satellite channels centered at the solar induced fluorescence
band. The hyperspectral remote sensing data collected from the Banana River and Indian River Lagoon watersheds
represents previously unknown signatures to be used in satellite and airborne remote sensing of water in turbid waters
along the US Atlantic Ocean coastal region and the Florida littoral zone.
In-situ measurement of bottom reflectance signatures and bottom features in water are used to test an analytical based irradiance model protocol. Comparisons between predicted and measured bottom reflectance signatures are obtained using measured hyperspectral remote sensing reflectance signatures, water depth and water column constituent concentrations. Analytical solutions and algorithms are used to generate synthetic signatures of different bottom types. The analytical methodology used to simulated bottom reflectance contains offset and bias that can be corrected using spectral window based corrections. Example results are demonstrated for application to coral species, submerged aquatic vegetation and a sand bottom type. Spectral windows are identified for predicting the above bottom types. Sensitivity analysis of predicted bottom reflectance signatures is conducted by varying water depth, chlorophyll, dissolved organic matter and total suspended mater concentrations. The protocol can be applied to shallow subsurface geospatial mapping using sensor based water surface reflectance based upon an analytical model solution derived from primitive radiative transfer theory.
Airborne, Satellite and In-Situ optical and acoustical imaging provides a means to characterize surface and subsurface water conditions in shallow marine systems. An important research topic to be studied during dredging operations in harbors and navigable waterways is the movement of fluidized muds before, during and after dredging operations. The fluid movement of the surficial sediments in the form of flocs, muck and mud is important to estimate in order to model the transport of solids material during dredging operations. Movement of highly turbid bottom material creates a lutocline or near bottom nephelometric layers, reduces the penetration of light reaching the water bottom. Monitoring and measurement systems recently developed for use in shallow marine areas, such as the Indian River Lagoon are discussed. Newly developed passive sondes and subsurface imaging are described. Methods and techniques for quantifying the mass density flux of total particulate matter demonstrate the use of multiple sensor systems for environmental monitoring and provide directional fluxes and movement of the fluidized solids. Airborne imaging of dredge site provide wide area surveillance during these activities. Passive sondes, optical imaging and acoustical sensors are used to understand horizontal and vertical mass flux processes. The passive sondes can be directionally oriented and are deployed during optical particle velocimetry system (OPVS) imaging of the flocs, particles and colloidal material motion. Comparison of the image based particle velocities are compared to electromagnetic and acoustic velocity imaging results. The newly developed imaging system provides a pathway for integration of subsurface hyperspectral imaging for particle compositional analysis.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.