53 research outputs found
Very Shallow Water Bathymetry Retrieval from Hyperspectral Imagery at the Virginia Coast Reserve (VCR\u2707) Multi-Sensor Campaign
A number of institutions, including the Naval Research Laboratory (NRL), have developed look up tables for remote retrieval of bathymetry and in-water optical properties from hyperspectral imagery (HSI) [6]. For bathymetry retrieval, the lower limit is the very shallow water case (here defined as \u3c 2m), a depth zone which is not well resolved by many existing bathymetric LIDAR sensors, such as SHOALS [4]. The ability to rapidly model these shallow water depths from HSI directly has potential benefits for combined HSI/LIDAR systems such as the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) [10]. In this study, we focused on the validation of a near infra-red feature, corresponding to a local minimum in absorption (and therefore a local peak in reflectance), which can be correlated directly to bathymetry with a high degree of confidence. Compared to other VNIR wavelengths, this particular near-IR feature corresponds to a peak in the correlation with depth in this very shallow water regime, and this is a spectral range where reflectance depends primarily on water depth (water absorption) and bottom type, with suspended constituents playing a secondary role
Recommended from our members
An investigation of the acoustic signature of the Dungeness crab (Cancer magister)
The acoustic signals produced by the Dungeness crab (Cancer
magister) were investigated. The signals were examined for duration times and frequency content. The signals were converted from analog to digital form, and the autocorrelation functions and the power density spectrums were determined.
The signals produced by Dungeness and Japanese red rock crabs
were found to last from 2. 8 to 30. 0 milliseconds. The frequencies contained in these signals ranged from 800 to 15000 hertz, the passband of the filter used in the signal recording process. The autocorrelation functions were found to possess either a decaying sinusoidal wave shape or a sinusoidal wave shape displaying a nodal and anti-nodal characteristic. Nodal and anti-nodal behavior was found in 65% of the male. Dungeness crab signals, and in 25% of the female Dungeness crab signals. The time period between nodes in the autocorrelation functions of signals produced by Dungeness crabs was generally found to be less than two milliseconds. The time period between nodes in autocorrelation functions of signals produced by a related species, the Japanese red rock crab, was generally found to
be four milliseconds. The power contained in a signal was found to
be concentrated in a narrow band of frequencies in a majority of the signals. The frequency containing the maximum power of the signal was found to be between 4000 hertz and 6000 hertz in 69% of the large Dungeness male signals. The Dungeness female signals contained maximum power frequencies in this range in only 35% of the signals, with a significant percentage, 30%, of the maximum power frequencies occurring below 2000 hertz
Dedicated JPSS VIIRS Ocean Color Calibration/Validation Cruise
The NOAA/STAR ocean color team is focused on “end-to-end” production of high quality satellite ocean color products. In situ validation of satellite data is essential to produce the high quality, “fit for purpose” remotely sensed ocean color products that are required and expected by all NOAA line offices, as well as by external (both applied and research) users. In addition to serving the needs of its diverse users within
the U.S., NOAA has an ever increasing role in supporting the international ocean color community and is actively engaged in the International Ocean-Colour Coordinating Group (IOCCG). The IOCCG, along with the Committee on Earth Observation Satellites (CEOS) Ocean Colour Radiometry Virtual Constellation (OCR-VC), is developing the International Network for Sensor Inter-comparison and Uncertainty assessment for Ocean Color Radiometry (INSITU-OCR). The INSITU-OCR has identified, amongst other issues, the crucial need for sustained in situ observations for product validation, with longterm measurement programs established and maintained beyond any individual mission.
Recently, the NOAA/STAR Ocean Color Team has been making in situ validation measurements continually since the launch in fall 2011 of the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) platform, part of the U.S. Joint Polar Satellite System (JPSS) program. NOAA ship time for the purpose of ocean color validation, however, had never been allocated until the cruise described herein. As the institutional lead for this cruise, NOAA/STAR invited external collaborators based on scientific
objectives and existing institutional collaborations. The invited collaborators are all acknowledged professionals in the ocean color remote sensing community. Most of the cruise principal investigators (PIs) are also PIs of the VIIRS Ocean Color Calibration and Validation (Cal/Val) team, including groups from Stennis Space Center/Naval Research Laboratory (SSC/NRL) and the University of Southern Mississippi (USM); City College of New York (CCNY); University of Massachusetts Boston (UMB); University of South Florida (USF); University of Miami (U. Miami); and, the National Institute of Standards and Technology (NIST). These Cal/Val PIs participated directly, sent qualified researchers
from their labs/groups, or else contributed specific instruments or equipment. Some of the cruise PIs are not part of the NOAA VIIRS Ocean Color Cal/Val team but were chosen to complement and augment the strengths of the Cal/Val team participants. Outside investigator groups included NASA Goddard Space Flight Center (NASA/GSFC), Lamont-Doherty Earth Observatory at Columbia University (LDEO), and the Joint Research Centre of the European Commission (JRC).
This report documents the November 2014 cruise off the U.S. East Coast aboard the NOAA Ship Nancy Foster. This cruise was the first dedicated ocean color validation cruise to be supported by the NOAA Office of Marine and Air Operations (OMAO). A second OMAO-supported cruise aboard the Nancy Foster is being planned for late 2015. We at NOAA/STAR are looking forward to continuing dedicated ocean color validation cruises, supported by OMAO on NOAA vessels, on an annual basis in support of JPSS VIIRS on SNPP, J-1, J-2 and other forthcoming satellite ocean color missions from the U.S as well as other countries. We also look forward to working with the U.S. and the international ocean community for improving our understanding of global ocean optical, biological, and biogeochemical properties.JRC.H.1-Water Resource
Recommended from our members
Optical scattering and backscattering by organic and inorganic particulates in U.S. coastal waters
We present the results of a study of optical scattering and backscattering of particulates for three coastal sites that represent a wide range of optical properties that are found in U.S. near-shore waters. The 6000 scattering and backscattering spectra collected for this study can be well approximated by a power-law function of wavelength. The power-law exponent for particulate scattering changes dramatically from site to site (and within each site) compared with particulate backscattering where all the spectra, except possibly the very clearest waters, cluster around a single wavelength power-law exponent of −0.94 . The particulate backscattering-to-scattering ratio (the backscattering ratio) displays a wide range in wavelength dependence. This result is not consistent with scattering models that describe the bulk composition of water as a uniform mix of homogeneous spherical particles with a Junge-like power-law distribution over all particle sizes. Simultaneous particulate organic matter (POM) and particulate inorganic matter (PIM) measurements are available for some of our optical measurements, and site-averaged POM and PIM mass-specific cross sections for scattering and backscattering can be derived. Cross sections for organic and inorganic material differ at each site, and the relative contribution of organic and inorganic material to scattering and backscattering depends differently at each site on the relative amount of material that is present
A vein bypass first versus a best endovascular treatment first revascularization strategy for patients with chronic limb-threatening ischaemia who require an infra-popliteal, with or without an additional more proximal infra-inguinal, revascularization procedure to restore limb perfusion:the BASIL-2 within-trial health economic analysis
BackgroundChronic limb-threatening ischaemia (CLTI) places a considerable socioeconomic burden health and social care systems worldwide. The objective of this health economic analysis was to investigate the cost-effectiveness (CEA) and cost-utility (CUA) of a vein bypass (VB) first versus a best endovascular treatment (BET) first revascularization strategy in patients with CLTI who require an infra-popliteal revascularization procedure to restore limb perfusion. Methods CEA and CUA analyses were conducted from the perspective of the UK National Health Service. Patient-level resource use and health outcomes data collected from the BASIL-2 trial over 2-7 years of follow-up were utilized to estimate incremental cost-effectiveness ratios expressed as cost per amputation-free life year (AFLY) and cost per quality-adjusted life year (QALY). EQ-5D-5L was used to generate participant QALYs at 2 and 3 years. Results At two years, the mean(s.d.) discounted hospital cost was £15 742.59(16 182.60) and £13 273.66(15 446.92) in the VB-first and BET-first revascularization strategy groups respectively. The lower costs (-£2524.23, 95% c.i., -£5844.93 to £1131.52) in the BET-first group were mainly due to the reduced number of days in hospital and lower procedural costs. BET-first was also more effective leading to additional AFLYs (0.429, 95% c.i., 0.03 to 0.88) at 7 years and discounted QALYs (0.016, 95% c.i., -0.08 to 0.12) at 2 years. Conclusion A best endovascular first revascularization strategy dominated a vein bypass first strategy in the cost-effectiveness and cost-utility analyses. The findings were robust across different scenarios and prespecified subgroups.<p/
Velocity fields and optical turbulence near the boundary in a strongly convective laboratory flow
Introducing SiTTE: A controlled laboratory setting to study the impact of turbulent fluctuations on light propagation in the underwater environment
Turbulent kinetic energy and temperature variance dissipation in laboratory generated Rayleigh-Bénard turbulence designed to study the distortion of light by underwater microstructure fluctuations
- …
