The GLO instrument concept is a VNIR/MWIR solar occultation sensor designed to measure (all at < 1 km vertical resolution) O3, H2O, CH4, CO, HF, HCN, HCl, HDO, N2O, CO2 (for temperature), and aerosol from orbital altitudes. The vertical measurement range spans the entire middle atmosphere, but the sensor has been designed to particularly target transport and composition in the UTLS. With its small form factor and modest spacecraft requirements, GLO is well suited for constellation applications. We will describe one such implementation of GLO. The instrument concept, measurement and data acquisition approach, and potential applications will be discussed.
Charles Bachmann, Deric Gray, Andrei Abelev, William Philpot, Marcos Montes, Robert Fusina, Joseph Musser, Rong-Rong Li, Michael Vermillion, Geoffrey Smith, Daniel Korwan, Charlotte Snow, W. David Miller, Joan Gardner, Mark Sletten, Georgi Georgiev, Barry Truitt, Marcus Killmon, Jon Sellars, Jason Woolard, Christopher Parrish, Art Schwarzscild
In June 2011, a multi-sensor airborne remote sensing campaign was flown at the Virginia Coast Reserve Long Term
Ecological Research site with coordinated ground and water calibration and validation (cal/val) measurements.
Remote sensing imagery acquired during the ten day exercise included hyperspectral imagery (CASI-1500),
topographic LiDAR, and thermal infra-red imagery, all simultaneously from the same aircraft. Airborne synthetic
aperture radar (SAR) data acquisition for a smaller subset of sites occurred in September 2011 (VCR'11). Focus
areas for VCR'11 were properties of beaches and tidal flats and barrier island vegetation and, in the water column,
shallow water bathymetry. On land, cal/val emphasized tidal flat and beach grain size distributions, density,
moisture content, and other geotechnical properties such as shear and bearing strength (dynamic deflection
modulus), which were related to hyperspectral BRDF measurements taken with the new NRL Goniometer for
Outdoor Portable Hyperspectral Earth Reflectance (GOPHER). This builds on our earlier work at this site in 2007
related to beach properties and shallow water bathymetry. A priority for VCR'11 was to collect and model
relationships between hyperspectral imagery, acquired from the aircraft at a variety of different phase angles, and
geotechnical properties of beaches and tidal flats. One aspect of this effort was a demonstration that sand density
differences are observable and consistent in reflectance spectra from GOPHER data, in CASI hyperspectral imagery,
as well as in hyperspectral goniometer measurements conducted in our laboratory after VCR'11.
In this paper, we investigate the use of nonlinear structure to derive the physical characteristics of coastal data. In particular, we show how the physics of shallow water coastal regions lead to well defined nonlinear structures (manifolds) in the corresponding hyperspectral data. The exact form of this structure is determined by both the Inherent Optical Properties of the water column as well as the boundary conditions (bottom reflectance, depth). This structure is then used to develop efficient algorithms for searching large 'lookup tables' of precalculated spectra with known physical characteristics, which are used for estimating the various physical parameters (bathymetry, bottom type, etc.) of the scene.
We assess our methods with data collected by the NRL PHILLS sensor at the Indian River Lagoon (IRL) in Florida. The IRL is a well-studied and characterized body of water that contains a number of different water and bottom types at various shallow (generally less than 8 meters, except in the shipping channel where depths can be as much as 18 m) depths. We show in particular that the search algorithm is able to produce valid results in a short amount of time, and compare our results with an IRL LIDAR bathymetry survey from early 2004.
This paper demonstrates the characterization of the water properties, bathymetry, and bottom type of the Indian River Lagoon (IRL) on the eastern coast of Florida using hyperspectral imagery. Images of this region were collected from an aircraft in July 2004 using the Portable Hyperspectral Imager for Low Light Spectroscopy (PHILLS). PHILLS is a Visible Near InfraRed (VNIR) spectrometer that was operated at an altitude of 3000 m providing 4 m resolution with 128 bands from 400 to 1000 nm. The IRL is a well studied water body that receives fresh water drainage from the Florida Everglades and also tidal driven flushing of ocean water through several outlets in the barrier islands. Ground truth measurements of the bathymetry of IRL were acquired from recent sonar and LIDAR bathymetry maps as well as water quality studies concurrent to the hyperspectral data collections. From these measurements, bottom types are known to include sea grass, various algae, and a gray mud with water depths less than 6 m over most of the lagoon. Suspended sediments are significant (~35 mg/m3) with chlorophyll levels less than 10 mg/m3 while the absorption due to Colored Dissolved Organic Matter (CDOM) is less than 1 m-1 at 440 nm. Hyperspectral data were atmospherically corrected using an NRL software package called Tafkaa and then subjected to a Look-Up Table (LUT) approach which matches hyperspectral data to calculated spectra with known values for bathymetry, suspended sediments, chlorophyll, CDOM, and bottom type.
The Naval Research Laboratory and the Boeing Company have teamed to fly the NRL ocean Portable Hyperspectral Imager for Low Light Spectroscopy (ocean PHILLS) on board the International Space Station (ISS). This joint program is named the Hyperspectral Sensor for Global Environmental Imaging and Analysis (HyGEIA). Hyperspectral images spanning the wavelength range 400 to 1000 nm will be collected at a ground sample distance of 25 m, with 10 nm spectral binning, and 200 to 1 signal to noise over the visible wavelengths for a 5% albedo scene. These images will be used to characterize the coastal ocean and littoral zone, crops, and forest areas. The PHILLS will also image over the same wavelength range at 130 m GSD to produce similar environmental products over a larger ground area. This paper will describe the modification of PHILLS required for use on the ISS, the modeled on orbit performance, and the planned on orbit configuration.
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