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Environmental effects on laser-induced fluorescence spectra of natural waters
Laser fluorosensing can be used to monitor dissolved organic carbon (DOC), but analysis of the data can be hindered by several environmental phenomena. These phenomena include attenuation of the laser beam and differential attenuation of the fluorescence by the water column, variability in the molecular weight composition of the DOC, and temperature, pH, and metal ion effects on DOC fluorescence. These factors are discussed in terms of their effect on laboratory and remote field data analysis. Experimental results are provided. Analysis of fluorosensor data of DOC may be improved by compensating for the environmental factors. An improved methodology is discussed, and a suggestion is made for indirect monitoring of pH and metal ion concentration.
Shipboard Sunphotometer Measurements of Aerosol Optical Depth Spectra and Columnar Water Vapor During ACE-2 and Comparison with Selected Land, Ship, Aircraft, and Satellite Measurements
Analyses of aerosol optical depth (AOD) and colurnmn water vapor (CWV) measurements acquired with NASA Ames Research Center's 6-channel Airborne Tracking Sunphotometer (AATS-6) operated aboard the R/V Professor Vodyanitskiy during the 2nd Aerosol Characterization Experiment (ACE-2) are discussed. Data are compared with various in situ and remote measurements for selected cases. The focus is on 10 July, when the Pelican airplane flew within 70 km of the ship near the time of a NOAA-14/AVHRR satellite overpass and AOD measurements with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) above the marine boundary layer (MBL) permitted calculation of AOD within the MBL from the AATS-6 measurements. A detailed column closure test is performed for MBL AOD on 10 July by comparing the AATS-6 MBL AODs with corresponding values calculated by combining shipboard particle size distribution measurements with models of hygroscopic growth and radiosonde humidity profiles (plus assumptions on the vertical profile of the dry particle size distribution and composition). Large differences (30-80% in the mid-visible) between measured and reconstructed AODs are obtained, in large part because of the high sensitivity of the closure methodology to hygroscopic growth models, which vary considerably and have not been validated over the necessary range of particle size/composition distributions. The wavelength dependence of AATS-6 AODs is compared with the corresponding dependence of aerosol extinction calculated from shipboard measurements of aerosol size distribution and of total scattering mearured by a shipboard integrating nephelometer for several days. Results are highly variable, illustrating further the great difficulty of deriving column values from point measurements. AATS-6 CWV values are shown to agree well with corresponding values derived from radiosonde measurements during 8 soundings on 7 days and also with values calculated from measurements taken on 10 July with the AATS-14 and the University of Washington Passive Humidigraph aboard the Pelican.
Shipboard Sunphotometer Measurements of Aerosol Optical Depth Spectra and Columnar Water Vapor During ACE-2, and Comparison with Selected Land, Ship, Aircraft, and Satellite Measurements
Analyses of aerosol optical depth (AOD) and columnar water vapor (CWV) measurements acquired with NASA Ames Research Center's six-channel Airborne Tracking Sunphotometer (AATS-6) operated aboard the R/V (research vehicle) Professor Vodyanitskiy during the second Aerosol Characterization Experiment (ACE-2) are discussed. Data are compared with various in situ and remote measurements for selected cases. The focus is on 10 July, when the Pelican airplane flew within 70 km of the ship near the time of a NOAA (National Oceanographic and Atmospheric Administration)-14/AVHRR (Advanced Very High Resolution Radiometer) satellite overpass and AOD measurements with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) above the marine boundary layer (MBL) permitted calculation of AOD within the MBL from the AATS-6 measurements. A detailed column closure test is performed for MBL AOD on 10 July by comparing the AATS-6 MBL AODs with corresponding values calculated by combining shipboard particle size distribution measurements with models of hygroscopic growth and radiosonde humidity profiles (plus assumptions on the vertical profile of the dry particle size distribution and composition). Large differences (30-80% in the mid-visible) between measured and reconstructed AODs are obtained, in large part because of the high sensitivity of the closure methodology to hygroscopic growth models, which vary considerably and have not been validated over the necessary range of particle size/composition distributions. The wavelength dependence of AATS-6 AODs is compared with the corresponding dependence of aerosol extinction calculated from shipboard measurements of aerosol size distribution and of total scattering measured by a shipboard integrating nephelometer for several days. Results are highly variable, illustrating further the great difficulty of deriving column values from point measurements. AATS-6 CWV values are shown to agree well with corresponding values derived from radiosonde measurements during eight soundings on seven days and also with values calculated from measurements taken on 10 July with the AATS-14 and the University of Washington Passive Humidigraph aboard the Pelican.
Retrieval of Surface Snow Grainsize and Melt Water from AVIRIS Spectra
The Earth's energy balance and hydrology are effected by the distribution and characteristics of snow cover on the surface. Snow grainsize and snow melt, influence surface albedo and hydrology.
Investigation of effects of background water on upwelled reflectance spectra and techniques for analysis of dilute primary-treated sewage sludge
In an effort to improve understanding of the effects of variations in background water on reflectance spectra, laboratory tests were conducted with various concentrations of sewage sludge diluted with several types of background water. The results from these tests indicate that reflectance spectra for sewage-sludge mixtures are dependent upon the reflectance of the background water. Both the ratio of sewage-sludge reflectance to background-water reflectance and the ratio of the difference in reflectance to background-water reflectance show spectral variations for different turbid background waters. The difference in reflectance is the only parameter considered.
Infrared reflectance spectra of asteroids - A search for water of hydration
Infrared reflectance spectra have shown the presence of an absorption feature in the 3-4 micron region for seven C and U asteroids. By comparison with laboratory spectra of terrestrial silicates and meteorites, it is concluded that this band is probably due to water in the form of hydrated salts and silicates (clay minerals), implying that the surface material of these asteroids may be analogous to the CI and CM carbonaceous chondritic meteorites. The presence of other hydrated minerals, however, cannot be ruled out. The depths of the water bands in the spectra vary from asteroid to asteroid, though no asteroid spectrum shows a band as deep as was detected on 1 Ceres. On four other C asteroids, no water band was detected. The implications of these observations for the mineralogy of these asteroids are discussed
Low-energy constraints on photoelectron spectra measured from liquid water and aqueous solutions
We report on the effects of electron collision and indirect ionization processes on the photoemission spectra of liquid water, specifically at photoexcitation and electron kinetic energies well below 30 eV.
Measured and calculated fast neutron spectra in a lead-and-water shielded reactor
Fast neutron spectra in lead and water shielded reactor, comparing liquid scintillator measurements with discrete ordinates code calculations
Deformation of fast neutron spectrum in concrete and water
Fast neutron spectra in concrete and water used as shielding
Study of the water dynamics near hydrophilic, nanostructured CuO surfaces by quasielastic and inelastic neutron scattering
We have used quasielastic and inelastic neutron scattering to investigate the structure, dynamics, and phase transitions of water interacting with superhydrophilic CuO surfaces that not only possess a strong affinity for water but also a “grass-like” topography that is rough on both micro- and nanoscales. Here, we report quasielastic neutron scattering (QENS) measurements on two samples differing in water content at five temperatures below 280 K. The QENS spectra show water undergoing two different types of diffusive motion near the CuO surfaces: a “slow” translational diffusion occurring on a nanosecond time scale and a faster rotational motion. Further from the surfaces, there is “fast” translational diffusion comparable in rate to that of bulk supercooled water and the rotational motion occurring in the interfacial water. Analysis of the QENS spectra supports wetting of water to the CuO blades as seen in electron microscopy images. In addition, we observe an anomalous temperature dependence of the QENS spectra on cooling from 270 to 230 K with features consistent with a liquid–liquid phase transition. We suggest that the solvent-like properties of the coexisting bulk-like water in our CuO samples are a significant factor in determining the temperature dependence of the interfacial water’s dynamics. Our results are compared with those obtained from two well-studied substrate classes: (1) silicas that contain ordered cylindrical nanopores but have weaker hydrophilicity and (2) nanoparticles of other transition-metal oxides, such as TiO 2 , which share the strong hydrophilicity of our samples but lack their porosity.
INFRARED SPECTRA OF STARS AND PLANETS II WATER VAPOR IN OMICRON CETI
Infrared spectra of stars and planets - part ii, water in omicron ceti
Requirements for airborne laser systems used in coastal studies
Requirements for airborne laser systems are considered for the following applications: (1) photo-optical determination of shallow water wave spectra; (2) bathymetry in highly turbid waters; (3) chlorophyll concentration monitoring; and (4) oil dispersion mapping.
A remote sensing laser fluorometer
A sensor is reported which is able to identify certain specific substances in water by means of their fluorescence spectra. In particular, the sensor detects oil, ligninsulfonates and chlorophyll. The device is able to measure the fluorescence spectra of water at ranges up to 75 m and to detect oil spills on water at altitudes up to 300 m. Blue light from a laser is used to excite the fluorescence of the target. Any light from the ambient background illumination, from the reflected laser light or from the induced fluorescence is gathered by a small telescope focused on the target. Optical filters are used to block the reflected laser light and to select the wavelengths of interest in the fluorescence spectrum of the target. The remaining light is detected with a photomultiplier tube. The amplitude of the laser induced fluorescence in the wavelength interval selected by the optical filters is displayed on a meter or strip chart recorder.
Laboratory upwelled radiance and reflectance spectra of Kerr reservoir sediment waters
Reflectance, chromaticity, and several other physical and chemical properties were measured for various water mixtures of bottom sediments taken from two sites at Kerr Reservoir, Virginia. Mixture concentrations ranged from 5 to 1000 ppm by weight of total suspended solids (TSS) in filtered deionized tap water. The two sets of radiance and reflectance spectra obtained were similar in shape and magnitude for comparable values of TSS. Upwelled reflectance was observed to be a nonlinear function of TSS with the degree of curvature a function of wavelength. Sediment from the downstream site contained a greater amount of particulate organic carbon than from the upstream site. No strong conclusions can be made regarding the effects of this difference on the radiance and reflectance spectra. Near-infrared wavelengths appear useful for measuring highly turbid water with concentrations up to 1000 ppm or more. Chromaticity characteristics do not appear useful for monitoring sediment loads above 150 ppm.
Remote detection of ocean waste
An application of characteristic vector analysis to ocean color spectra for the detection of pollutants in water is described. The technique can be useful for detecting and distinguishing among a variety of substances in the water. The analysis also illustrates the variability of the water color spectra with both concentration and depth distribution. Both concentration and depth information may be extractable from passive multispectral data under certain circumstances.
Far infrared spectra of amorphous and crystalline water ice and changes in these phases as the result of proton irradiation
Far infrared spectra from 20 microns (500 cm(sup -1)) to 100 microns (100 cm(sup -1)) of water ice were measured. Amorphous ice deposited at 13 K has one absorption band at 45 microns (220 cm(sup -1)). Amorphous ice evolves into a crystalline form with absorptions at 44 microns (229 cm(sup -1)) and 62 microns (162 cm(sup -1)) as the temperature is increased to 155 K. Spectra documenting this phase change are presented as well as spectra of crystalline ice at temperatures between 13 K and 155 K. Far infrared spectra of amorphous and crystalline water ice before and after proton irradiation are also presented. Changes in these two forms are discussed in relation to ices in comets, grains, and planetary satellites in various radiation environments. Observations of non-terrestrial clathrate hydrates are still lacking despite the fact that clathrates first were suggested to exist in cometary and interstellar ices over forty years ago. Spectroscopy, the most direct method of astronomical detection, has been hampered by the similarity of clathrate hydrate spectra to those of unenclathrated guest molecules and solid H2O. A methanol (CH3OH) clathrate hydrate, using a recently published procedure, was prepared and its far-IR spectrum investigated. The spectrum is quite differenct from that of either unenclathrated CH3OH or solid H2O and so should be of value in astronomical searches for this clathrate.