Goody C.,Sea Engineering Inc.
OCEANS 2013 MTS/IEEE - San Diego: An Ocean in Common | Year: 2013
Sea Engineering, Inc. conducted a detailed 14-month study to investigate sand transport processes and beach erosion at Kapa'a Beach and develop beach improvement alternatives. The study consisted of the following key components: evaluation of sand transport mechanisms and processes acting along the shoreline at Kapa'a; identification of potential beach material borrow sites and available volumes through a geophysical investigation of offshore sand deposits; development of computational wave and circulation models for nearshore Kapa'a Beach using advanced numerical modeling and visualization software; and, development of coastal engineering improvement concepts for mitigation of beach loss and shoreline retreat at Kapa'a Beach. © 2013 MTS.
Jones C.A.,Sea Engineering Inc. |
Jaffe B.E.,U.S. Geological Survey
Marine Geology | Year: 2013
Morphological trends of three distinct intertidal environments in South San Francisco Bay were investigated using a combination of measurement and modeling tools. Because of the inherent relationship between the physical environment and the sediment properties, the sediment properties provide a good indicator of morphologic trends. A significant finding of this study is that surface sediment erodibility increases as the energy level in the environment increases. Conversely subsurface sediment erodibility shows a strong relationship to the long-term history of the site. The combination of the measured sediment properties, the history of deposition and erosion, and simple modeling of the physical environment illustrate the interaction of these properties such that an understanding of intertidal flat behavior is developed. © 2013 Elsevier B.V.
Nencioli F.,University of California at Santa Barbara |
Chang G.,Sea Engineering Inc. |
Twardowski M.,WET Labs Inc. |
Dickey T.D.,University of California at Santa Barbara
Biogeosciences | Year: 2010
Optical properties were collected along a transect across cyclonic eddy Opal in the lee of Hawaii during the E-Flux III field experiment (10-27 March 2005). The eddy was characterized by an intense doming of isopycnal surfaces, and by an enhanced Deep Chlorophyll Maximum Layer (DCML) within its core. The phytoplankton bloom was diatom dominated, evidencing an eddy-induced shift in ecological community. Four distinct regions were identified throughout the water column at Opal's core: a surface mixed layer dominated by small phytoplankton; a layer dominated by "senescent" diatoms between the bottom of the upper mixed layer and the DCML; the DCML; and a deep layer characterized by decreasing phytoplankton activity. We focused on two parameters, the ratio of chlorophyll concentration to particulate beam attenuation coefficient, [chl]/ c, and the backscattering ratio (the particle backscattering to particle scattering ratio), b̃bp, and tested their sensitivity to the changes in particle composition observed through the water column at the eddy center. Our results show that [chl]/ c is not a good indicator. Despite the shift in ecological community, the ratio remains controlled primarily by the variation in chlorophyll concentration per cell with depth (photoadaptation), so that its values increase throughout the DCML. Steeper increase of [chl]/ c below the DCML suggest that remineralization might be another important controlling factor. On the other hand, b̃bp clearly indicates a shift from a small phytoplankton to a diatom dominated community. Below an upper layer characterized by constant values, the b̃bp showed a rapid decrease to a broad minimum within the DCML. The higher values below the DCML are consistent with enhanced remineralization below the eddy-induced bloom. Both the "senescent" and the "healthy" diatom layers are characterized by similar optical properties, indicating some possible limitations in using optical measurements to fully characterize the composition of suspended material in the water column. The inverse relationship between b̃bp and [chl]/ c, reported by others for Case II waters, is observed neither for the background conditions, nor in the presence of the eddy-induced diatom bloom. Between the two parameters, only the backscattering ratio showed the potential to be a successful indicator for changes in particle composition in Case I waters. © Author(s) 2010.
Barry J.H.,Sea Engineering Inc.
OCEANS'11 - MTS/IEEE Kona, Program Book | Year: 2011
Sea Engineering, Inc. (SEI) has continued long-standing efforts to find exploitable offshore sand resources for the purpose of nourishing Hawaii's beaches. Investigations by University of Hawaii researchers in the 1970's established the potential presence of large bodies of sand in ancient offshore alluvial channels and wave-cut terraces. Sampling efforts showed that much of the sand was too fine-grained to be useful as beach nourishment. Prospecting was revived in the early 1990's with funding for new surveys provided by the U.S. Bureau of Mines through the Marine Minerals Technology Center at the University of Hawaii. The realization that existing instrumentation was not adequate for useful imaging of Hawaii sand deposits led to a team effort by SEI and Precision Signal, Inc., funded by CEROS to develop a state-of-the-art sub-bottom profiling system. The new chirp profiler resulted in excellent sub-bottom imagery. SEI successfully mapped selected sand deposits with the new instrument around the island of Oahu for the United States Geological Survey (USGS) in 1996 and 1998. © 2011 MTS.
Chang G.,Sea Engineering Inc. |
Twardowski M.S.,WET Labs Inc.
Journal of Geophysical Research: Oceans | Year: 2011
We computed the modulation transfer function (MTF), which is the magnitude of the Fourier transform of the point spread function, for two different water bodies using measurements of optical properties and analytical formulations. Knowledge of the MTF is important for the interpretation of images from underwater electro-optical systems. The data were collected from two field sites as part of the Office of Naval Research sponsored Radiance in a Dynamic Ocean program: (1) Scripps Institution of Oceanography (SIO) Pier, a shallow-water, eutrophic environment, and (2) the Santa Barbara Channel (SBC), a deeper, mesotrophic environment. Wavelet analysis was employed to investigate the sources of variability of the MTF and the periodicities at which they occur. Results suggest that the MTF was strongly related to wind conditions and advection events and the optical properties serving as proxies for particle concentration and composition in the SBC. Increased wind speeds and stresses resulted in upper water column mixing, decreased water clarity, and reductions in image transmission. Rip currents accompanied by high concentrations of reflective particles observed at SIO Pier resulted in increases in the MTF. Optically derived particle composition characteristics such as the bulk particle real index of refraction and particle size distribution are shown to be related to the variability of imaging performance at both field sites. © 2011 by the American Geophysical Union.