Spectral emissivity of tungsten: analytic expressions for the 340-nm to 2.6-μm spectral region

International Nuclear Information System (INIS)

Pon, R.M.; Hessler, J.P.

1984-01-01

To correct emission spectra a standard radiance source is often used to determine the spectral responsivity of the detection system. In the near-UV, visible, and near-IR spectral regions the most common radiance standard is a tungsten strip lamp calibrated by a standards laboratory. For day-to-day experiments where slightly less accuracy is acceptable, a less expensive uncalibrated lamp is useful. In this case, the radiant temperature T/sub r/ of the lamp is measured with an optical pyrometer, generally at a single wavelength such as 650 nm, and the source spectral radiance L(λ) is calculated from L(λ) = tau(λ)epsilon(λ,T)L/sub B/(λ,T). The transmittance of the source is tau(λ), the spectral emissivity is epsilon(λ,T), and L/sub B/(λ,T) is the spectral distribution of blackbody radiation, Planck's radiation law. To obtain the true temperature T, Wien's approximation is employed. To conveniently calibrate a system, especially one which utilizes a microcomputer, it is advantageous to have analytic expressions for the spectral emissivity of tungsten. Although Larrabee has published such expressions, they are limited to the 450-800-nm spectral region. To obtain analytic expressions from 340 nm to 2.6 μm they have used the measurements of DeVos. Although DeVos's results differ by 2% from those of Larrabee, this difference is assumed to be acceptable

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

Science.gov (United States)

Wolf, Kevin; Ehrlich, André; Hüneke, Tilman; Pfeilsticker, Klaus; Werner, Frank; Wirth, Martin; Wendisch, Manfred

2017-03-01

Spectral radiance measurements collected in nadir and sideward viewing directions by two airborne passive solar remote sensing instruments, the Spectral Modular Airborne Radiation measurement sysTem (SMART) and the Differential Optical Absorption Spectrometer (mini-DOAS), are used to compare the remote sensing results of cirrus optical thickness τ. The comparison is based on a sensitivity study using radiative transfer simulations (RTS) and on data obtained during three airborne field campaigns: the North Atlantic Rainfall VALidation (NARVAL) mission, the Mid-Latitude Cirrus Experiment (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems (ACRIDICON) campaign. Radiative transfer simulations are used to quantify the sensitivity of measured upward radiance I with respect to τ, ice crystal effective radius reff, viewing angle of the sensor θV, spectral surface albedo α, and ice crystal shape. From the calculations it is concluded that sideward viewing measurements are generally better suited than radiance data from the nadir direction to retrieve τ of optically thin cirrus, especially at wavelengths larger than λ = 900 nm. Using sideward instead of nadir-directed spectral radiance measurements significantly improves the sensitivity and accuracy in retrieving τ, in particular for optically thin cirrus of τ ≤ 2. The comparison of retrievals of τ based on nadir and sideward viewing radiance measurements from SMART, mini-DOAS and independent estimates of τ from an additional active remote sensing instrument, the Water Vapor Lidar Experiment in Space (WALES), shows general agreement within the range of measurement uncertainties. For the selected example a mean τ of 0.54 ± 0.2 is derived from SMART, and 0.49 ± 0.2 by mini-DOAS nadir channels, while WALES obtained a mean value of τ = 0.32 ± 0.02 at 532 nm wavelength, respectively. The mean of τ derived from the sideward viewing mini

Remote measurement of water color in coastal waters. [spectral radiance data used to obtain quantitative values for chlorophyll and turbidity

Science.gov (United States)

Weldon, J. W.

1973-01-01

An investigation was conducted to develop procedure to obtain quantitative values for chlorophyll and turbidity in coastal waters by observing the changes in spectral radiance of the backscattered spectrum. The technique under consideration consists of Examining Exotech model 20-D spectral radiometer data and determining which radiance ratios best correlated with chlorophyll and turbidity measurements as obtained from analyses of water samples and sechi visibility readings. Preliminary results indicate that there is a correlation between backscattered light and chlorophyll concentration and secchi visibility. The tests were conducted with the spectrometer mounted in a light aircraft over the Mississippi Sound at altitudes of 2.5K, 2.8K and 10K feet.

Far-infrared Spectral Radiance Observations and Modeling of Arctic Cirrus: Preliminary Results From RHUBC

Science.gov (United States)

Humpage, Neil; Green, Paul D.; Harries, John E.

2009-03-01

Recent studies have highlighted the important contribution of the far-infrared (electromagnetic radiation with wavelengths greater than 12 μm) to the Earth's radiative energy budget. In a cloud-free atmosphere, a significant fraction of the Earth's cooling to space from the mid- and upper troposphere takes place via the water vapor pure rotational band between 17 and 33 μm. Cirrus clouds also play an important role in the Earth's outgoing longwave radiation. The effect of cirrus on far-infrared radiation is of particular interest, since the refractive index of ice depends strongly on wavelength in this spectral region. The scattering properties of ice crystals are directly related to the refractive index, so consequently the spectral signature of cirrus measured in the FIR is sensitive to the cloud microphysical properties [1, 2]. By examining radiances measured at wavelengths between the strong water vapor absorption lines in the FIR, the understanding of the relationship between cirrus microphysics and the radiative transfer of thermal energy through cirrus may be improved. Until recently, very few observations of FIR spectral radiances had been made. The Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) was developed by Imperial College to address this lack of observational data. TAFTS observes both zenith and nadir radiances at 0.1 cm-1 resolution, between 80 and 600 cm-1. During February and March 2007, TAFTS was involved in RHUBC (the Radiative Heating in Under-explored Bands Campaign), an ARM funded field campaign based at the ACRF-North Slope of Alaska site near Barrow, situated at 71° latitude. Infrared zenith spectral observations were taken by both TAFTS and the AERI-ER (spectral range 400-3300 cm-1) from the ground during both cloud-free and cirrus conditions. A wide range of other instrumentation was also available at the site, including a micropulse lidar, 35 GHz radar and the University of Colorado/NOAA Ground-based Scanning Radiometer

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

OpenAIRE

Wolf, Kevin; Ehrlich, André; Hüneke, Tilman; Pfeilsticker, Klaus; Werner, Frank; Wirth, Martin; Wendisch, Manfred

2017-01-01

Spectral radiance measurements collected in nadir and sideward viewing directions by two airborne passive solar remote sensing instruments, the Spectral Modular Airborne Radiation measurement sysTem (SMART) and the Differential Optical Absorption Spectrometer (mini-DOAS), are used to compare the remote sensing results of cirrus optical thickness τ. The comparison is based on a sensitivity study using radiative transfer simulations (RTS) and on data obtained during three airb...

Camouflage in thermal IR: spectral design

Science.gov (United States)

Pohl, Anna; Fagerström, Jan; Kariis, Hans; Lindell, Roland; Hallberg, Tomas; Högström, Herman

2016-10-01

In this work a spectral designed coating from SPECTROGON is evaluated. Spectral design in this case means that the coating has a reflectivity equal to one at 3-5 and 8-12 microns were sensors operate and a much lower reflectivity in the other wave length regions. Three boxes are evaluated: one metallic, one black-body and one with a spectral designed surface, all with a 15 W radiator inside the box. It is shown that the box with the spectral designed surface can combine the two good characteristics of the other boxes: low signature from the metallic box and reasonable inside temperature from the black-body box. The measurements were verified with calculations using RadThermIR.

Contributed Review: Absolute spectral radiance calibration of fiber-optic shock-temperature pyrometers using a coiled-coil irradiance standard lamp

Energy Technology Data Exchange (ETDEWEB)

Fat’yanov, O. V., E-mail: fatyan1@gps.caltech.edu; Asimow, P. D., E-mail: asimow@gps.caltech.edu [Division of Geological and Planetary Sciences 252-21, California Institute of Technology, Pasadena, California 91125 (United States)

2015-10-15

We describe an accurate and precise calibration procedure for multichannel optical pyrometers such as the 6-channel, 3-ns temporal resolution instrument used in the Caltech experimental geophysics laboratory. We begin with a review of calibration sources for shock temperatures in the 3000-30 000 K range. High-power, coiled tungsten halogen standards of spectral irradiance appear to be the only practical alternative to NIST-traceable tungsten ribbon lamps, which are no longer available with large enough calibrated area. However, non-uniform radiance complicates the use of such coiled lamps for reliable and reproducible calibration of pyrometers that employ imaging or relay optics. Careful analysis of documented methods of shock pyrometer calibration to coiled irradiance standard lamps shows that only one technique, not directly applicable in our case, is free of major radiometric errors. We provide a detailed description of the modified Caltech pyrometer instrument and a procedure for its absolute spectral radiance calibration, accurate to ±5%. We employ a designated central area of a 0.7× demagnified image of a coiled-coil tungsten halogen lamp filament, cross-calibrated against a NIST-traceable tungsten ribbon lamp. We give the results of the cross-calibration along with descriptions of the optical arrangement, data acquisition, and processing. We describe a procedure to characterize the difference between the static and dynamic response of amplified photodetectors, allowing time-dependent photodiode correction factors for spectral radiance histories from shock experiments. We validate correct operation of the modified Caltech pyrometer with actual shock temperature experiments on single-crystal NaCl and MgO and obtain very good agreement with the literature data for these substances. We conclude with a summary of the most essential requirements for error-free calibration of a fiber-optic shock-temperature pyrometer using a high-power coiled tungsten halogen

IR radiation characteristics of rocket exhaust plumes under varying motor operating conditions

Directory of Open Access Journals (Sweden)

Qinglin NIU

2017-06-01

Full Text Available The infrared (IR irradiance signature from rocket motor exhaust plumes is closely related to motor type, propellant composition, burn time, rocket geometry, chamber parameters and flight conditions. In this paper, an infrared signature analysis tool (IRSAT was developed to understand the spectral characteristics of exhaust plumes in detail. Through a finite volume technique, flow field properties were obtained through the solution of axisymmetric Navier-Stokes equations with the Reynolds-averaged approach. A refined 13-species, 30-reaction chemistry scheme was used for combustion effects and a k-ε-Rt turbulence model for entrainment effects. Using flowfield properties as input data, the spectrum was integrated with a line of sight (LOS method based on a single line group (SLG model with Curtis-Godson approximation. The model correctly predicted spectral distribution in the wavelengths of 1.50–5.50 μm and had good agreement for its location with imaging spectrometer data. The IRSAT was then applied to discuss the effects of three operating conditions on IR signatures: (a afterburning; (b chamber pressure from ignition to cutoff; and (c minor changes in the ratio of hydroxyl-terminated polybutadiene (HTPB binder to ammonium perchlorate (AP oxidizer in propellant. Results show that afterburning effects can increase the size and shape of radiance images with enhancement of radiation intensity up to 40%. Also, the total IR irradiance in different bands can be characterized by a non-dimensional chamber pressure trace in which the maximum discrepancy is less than 13% during ignition and engine cutoff. An increase of chamber pressure can lead to more distinct diamonds, whose distance intervals are extended, and the position of the first diamond moving backwards. In addition, an increase in HTPB/AP causes a significant jump in spectral intensity. The incremental rates of radiance intensity integrated in each band are linear with the increase of HTPB

The Expected Impacts of NPOESS Microwave and Infrared Sounder Radiances on Operational Numerical Weather Prediction and Data Assimilation Systems

Science.gov (United States)

Swadley, S. D.; Baker, N.; Derber, J.; Collard, A.; Hilton, F.; Ruston, B.; Bell, W.; Candy, B.; Kleespies, T. J.

2009-12-01

The NPOESS atmospheric sounding functionality will be accomplished using two separate sensor suites, the combined infrared (IR) and microwave (MW) sensor suite (CrIMSS), and the Microwave Imager/Sounder (MIS) instrument. CrIMSS consists of the Cross Track Infrared Sounder (CrIS) and the cross track Advanced Technology Microwave Sounder (ATMS), and is scheduled to fly on the NPOESS Preparatory Project (NPP), and NPOESS operational flight units C1 and C3. The MIS is a conical scanning polarimetric imager and sounder patterned after the heritage WindSat, and DMSP Special Sensor Microwave Imagers and Sounders (SSMI and SSMIS), and is scheduled for flight units C2, C3 and C4. ATMS combines the current operational Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sounder (MHS), but with an additional channel in the 51.76 GHz oxygen absorption region and 3 additional channels in the 165.5 and 183 GHz water vapor absorption band. CrIS is a Fourier Transform Spectrometer and will provide 159 shortwave IR channels, 433 mid-range IR channels, and 713 longwave IR channels. The heritage sensors for CrIS are the NASA Advanced Infrared Sounder (AIRS) and the MetOp-A Infrared Atmospheric Sounding Interferometer (IASI). Both AIRS and IASI are high quality, high spectral resolution sounders which represent a significant improvement in the effective vertical resolution over previous IR sounders. This presentation will give an overview of preparations underway for day-1 monitoring of NPP/NPOESS radiances, and subsequent operational radiance assimilation. These preparations capitalize on experience gained during the pre-launch preparations, sensor calibration/validation and operational assimilation for the heritage sensors. One important step is to use pre-flight sensor channel specifications, noise estimates and knowledge of the antenna patterns, to generate and test proxy NPP/NPOESS sensor observations in existing assimilation systems. Other critical factors for

Use of the ARM Measurements of Spectral Zenith Radiance for Better Understanding of 3D Cloud-Radiation Processes & Aerosol-Cloud Interaction

Energy Technology Data Exchange (ETDEWEB)

Alexander Marshak; Warren Wiscombe; Yuri Knyazikhin; Christine Chiu

2011-05-24

We proposed a variety of tasks centered on the following question: what can we learn about 3D cloud-radiation processes and aerosol-cloud interaction from rapid-sampling ARM measurements of spectral zenith radiance? These ARM measurements offer spectacular new and largely unexploited capabilities in both the temporal and spectral domains. Unlike most other ARM instruments, which average over many seconds or take samples many seconds apart, the new spectral zenith radiance measurements are fast enough to resolve natural time scales of cloud change and cloud boundaries as well as the transition zone between cloudy and clear areas. In the case of the shortwave spectrometer, the measurements offer high time resolution and high spectral resolution, allowing new discovery-oriented science which we intend to pursue vigorously. Research objectives are, for convenience, grouped under three themes: • Understand radiative signature of the transition zone between cloud-free and cloudy areas using data from ARM shortwave radiometers, which has major climatic consequences in both aerosol direct and indirect effect studies. • Provide cloud property retrievals from the ARM sites and the ARM Mobile Facility for studies of aerosol-cloud interactions. • Assess impact of 3D cloud structures on aerosol properties using passive and active remote sensing techniques from both ARM and satellite measurements.

Physical Mechanism, Spectral Detection, and Potential Mitigation of 3D Cloud Effects on OCO-2 Radiances and Retrievals

Science.gov (United States)

Cochrane, S.; Schmidt, S.; Massie, S. T.; Iwabuchi, H.; Chen, H.

2017-12-01

Analysis of multiple partially cloudy scenes as observed by OCO-2 in nadir and target mode (published previously and reviewed here) revealed that XCO2 retrievals are systematically biased in presence of scattered clouds. The bias can only partially be removed by applying more stringent filtering, and it depends on the degree of scene inhomogeneity as quantified with collocated MODIS/Aqua imagery. The physical reason behind this effect was so far not well understood because in contrast to cloud-mediated biases in imagery-derived aerosol retrievals, passive gas absorption spectroscopy products do not depend on the absolute radiance level and should therefore be less sensitive to 3D cloud effects and surface albedo variability. However, preliminary evidence from 3D radiative transfer calculations suggested that clouds in the vicinity of an OCO-2 footprint not only offset the reflected radiance spectrum, but introduce a spectrally dependent perturbation that affects absorbing channels disproportionately, and therefore bias the spectroscopy products. To understand the nature of this effect for a variety of scenes, we developed the OCO-2 radiance simulator, which uses the available information on a scene (e.g., MODIS-derived surface albedo, cloud distribution, and other parameters) as the basis for 3D radiative transfer calculations that can predict the radiances observed by OCO-2. We present this new tool and show examples of its utility for a few specific scenes. More importantly, we draw conclusions about the physical mechanism behind this 3D cloud effect on radiances and ultimately OCO-2 retrievals, which involves not only the clouds themselves but also the surface. Harnessed with this understanding, we can now detect cloud vicinity effects in the OCO-2 spectra directly, without actually running the 3D radiance simulator. Potentially, it is even possible to mitigate these effects and thus increase data harvest in regions with ubiquitous cloud cover such as the Amazon

Service Oriented Gridded Atmospheric Radiances (SOAR)

Science.gov (United States)

Halem, M.; Goldberg, M. D.; Tilmes, C.; Zhou, L.; Shen, S.; Yesha, Y.

2005-12-01

We are developing a scalable web service tool that can provide complex griding services on-demand for atmospheric radiance data sets from multiple temperature and moisture sounding sensors on the NASA and NOAA polar orbiting satellites collected over the past three decades. This server-to-server middle ware tool will provide the framework for transforming user requests for an arbitrary spatial/temporal/spectral gridded radiance data set from one or more instruments into an action to invoke a griding process from a set of scientifically validated application programs that have been developed to perform such functions. The invoked web service agents will access, subset, concatenate, convolve, perform statistical and physically based griding operations and present the data as specified level 3 gridded fields for analysis and visualization in multiple formats. Examples of the griding operations consist of spatial-temporal radiance averaging accounting for the field of view instrument response function, first footprint in grid bin, selecting min/max brightness temperatures within a grid element, ratios of channels, filtering, convolving high resolution spectral radiances to match broader band spectral radiances, limb adjustments, calculating variances of radiances falling in grid box and creating visual displays of these fields. The gridded web services tool will support both human input through a WWW GUI as well as a direct computer request through a W3C SOAP/XML web service interface. It will generate regional and global gridded data sets on demand. A second effort will demonstrate the ability to locate, access, subset and grid radiance data for any time period and resolution from remote archives of NOAA and NASA data. The system will queue the work flow requests, stage processing and delivery of arbitrary gridded data sets in a data base and notify the users when the request is completed. This tool will greatly expand satellite sounding data utilization by

Estimates of radiance reflected towards the zenith at the surface of the sea

Directory of Open Access Journals (Sweden)

E. Aas

2010-10-01

Full Text Available Remote sensing of water colour by ship-mounted sensors represents an important tool for the validation of satellite products and the monitoring of water quality. The recorded radiance from the sea has to be corrected for the surface-reflected radiance from sun and sky in order to obtain the water-leaving radiance. Here the simple case of radiance reflected towards the zenith is studied. A set of observed sky radiance and solar irradiance data from Oslo has been used together with a Gaussian slope distribution for the sea surface in order to estimate the reflected radiance. The spectral range studied is 405–650 nm, the solar zenith angles are in the range 37°–76°, and the wind speeds are up to 10 m s⁻¹. The analysis of the results show that the reflected radiance has to be separated into three contributions: sky radiance and sun rays reflected at the foam-free surface and irradiance reflected by whitecaps and foam. It is then demonstrated that by using four input values, namely the downward irradiance, the sky radiance from the zenith, the solar zenith angle and the wind speed, it is possible to obtain by simple expressions estimates of the reflected radiance that only differ from the former calculated values by relative errors of less than 5%. The analysis also indicates that for the spectral range studied neither the water-leaving radiance nor the surface-reflected radiance can be disregarded relative to the other one in the Case 2 waters of the Oslofjord-Skagerrak area. The results form a first step towards the study of reflected radiance in viewing angles differing from the nadir direction.

Bioluminescence in a complex coastal environment: 1. Temporal dynamics of nighttime water-leaving radiance

Science.gov (United States)

Moline, Mark A.; Oliver, Matthew J.; Mobley, Curtis D.; Sundman, Lydia; Bensky, Thomas; Bergmann, Trisha; Bissett, W. Paul; Case, James; Raymond, Erika H.; Schofield, Oscar M. E.

2007-11-01

Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water-leaving radiance from blue (˜474 nm) to green as light propagated to the surface. In addition to clues in ecosystem responses to physical forcing, the temporal dynamics in intensity and spectral quality of water-leaving radiance provide suitable ranges for assessing detection. This may provide the information needed to estimate the depth of internal light sources in the ocean, which is discussed in part 2 of this paper.

Radiometric and spectral calibrations of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) using principle component analysis

Science.gov (United States)

Tian, Jialin; Smith, William L.; Gazarik, Michael J.

2008-10-01

The ultimate remote sensing benefits of the high resolution Infrared radiance spectrometers will be realized with their geostationary satellite implementation in the form of imaging spectrometers. This will enable dynamic features of the atmosphere's thermodynamic fields and pollutant and greenhouse gas constituents to be observed for revolutionary improvements in weather forecasts and more accurate air quality and climate predictions. As an important step toward realizing this application objective, the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) Engineering Demonstration Unit (EDU) was successfully developed under the NASA New Millennium Program, 2000-2006. The GIFTS-EDU instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw GIFTS interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. The radiometric calibration is achieved using internal blackbody calibration references at ambient (260 K) and hot (286 K) temperatures. The absolute radiometric performance of the instrument is affected by several factors including the FPA off-axis effect, detector/readout electronics induced nonlinearity distortions, and fore-optics offsets. The GIFTS-EDU, being the very first imaging spectrometer to use ultra-high speed electronics to readout its large area format focal plane array detectors, operating at wavelengths as large as 15 microns, possessed non-linearity's not easily removable in the initial calibration process. In this paper, we introduce a refined calibration technique that utilizes Principle Component (PC) analysis to compensate for instrument distortions and artifacts remaining after the initial radiometric calibration process, thus, further enhance the absolute calibration accuracy. This method is

The Cross-Calibration of Spectral Radiances and Cross-Validation of CO2 Estimates from GOSAT and OCO-2

Directory of Open Access Journals (Sweden)

Fumie Kataoka

2017-11-01

Full Text Available The Greenhouse gases Observing SATellite (GOSAT launched in January 2009 has provided radiance spectra with a Fourier Transform Spectrometer for more than eight years. The Orbiting Carbon Observatory 2 (OCO-2 launched in July 2014, collects radiance spectra using an imaging grating spectrometer. Both sensors observe sunlight reflected from Earth’s surface and retrieve atmospheric carbon dioxide (CO2 concentrations, but use different spectrometer technologies, observing geometries, and ground track repeat cycles. To demonstrate the effectiveness of satellite remote sensing for CO2 monitoring, the GOSAT and OCO-2 teams have worked together pre- and post-launch to cross-calibrate the instruments and cross-validate their retrieval algorithms and products. In this work, we first compare observed radiance spectra within three narrow bands centered at 0.76, 1.60 and 2.06 µm, at temporally coincident and spatially collocated points from September 2014 to March 2017. We reconciled the differences in observation footprints size, viewing geometry and associated differences in surface bidirectional reflectance distribution function (BRDF. We conclude that the spectral radiances measured by the two instruments agree within 5% for all bands. Second, we estimated mean bias and standard deviation of column-averaged CO2 dry air mole fraction (XCO2 retrieved from GOSAT and OCO-2 from September 2014 to May 2016. GOSAT retrievals used Build 7.3 (V7.3 of the Atmospheric CO2 Observations from Space (ACOS algorithm while OCO-2 retrievals used Version 7 of the OCO-2 retrieval algorithm. The mean biases and standard deviations are −0.57 ± 3.33 ppm over land with high gain, −0.17 ± 1.48 ppm over ocean with high gain and −0.19 ± 2.79 ppm over land with medium gain. Finally, our study is complemented with an analysis of error sources: retrieved surface pressure (Psurf, aerosol optical depth (AOD, BRDF and surface albedo inhomogeneity. We found no change in XCO2

Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort Under Clear Sky and Slightly Overcast Conditions.

Science.gov (United States)

Sandmann, Henner; Stick, Carsten

2014-01-01

Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes. © 2013 The American Society of Photobiology.

Characterization of protein and carbohydrate mid-IR spectral features in crop residues

Science.gov (United States)

Xin, Hangshu; Zhang, Yonggen; Wang, Mingjun; Li, Zhongyu; Wang, Zhibo; Yu, Peiqiang

2014-08-01

To the best of our knowledge, a few studies have been conducted on inherent structure spectral traits related to biopolymers of crop residues. The objective of this study was to characterize protein and carbohydrate structure spectral features of three field crop residues (rice straw, wheat straw and millet straw) in comparison with two crop vines (peanut vine and pea vine) by using Fourier transform infrared spectroscopy (FTIR) technique with attenuated total reflectance (ATR). Also, multivariate analyses were performed on spectral data sets within the regions mainly related to protein and carbohydrate in this study. The results showed that spectral differences existed in mid-IR peak intensities that are mainly related to protein and carbohydrate among these crop residue samples. With regard to protein spectral profile, peanut vine showed the greatest mid-IR band intensities that are related to protein amide and protein secondary structures, followed by pea vine and the rest three field crop straws. The crop vines had 48-134% higher spectral band intensity than the grain straws in spectral features associated with protein. Similar trends were also found in the bands that are mainly related to structural carbohydrates (such as cellulosic compounds). However, the field crop residues had higher peak intensity in total carbohydrates region than the crop vines. Furthermore, spectral ratios varied among the residue samples, indicating that these five crop residues had different internal structural conformation. However, multivariate spectral analyses showed that structural similarities still exhibited among crop residues in the regions associated with protein biopolymers and carbohydrate. Further study is needed to find out whether there is any relationship between spectroscopic information and nutrition supply in various kinds of crop residue when fed to animals.

Spectral radiance of strong lines in positive column mercury discharges with argon carrier gas

International Nuclear Information System (INIS)

Sansonetti, Craig J; Reader, Joseph

2006-01-01

The spectral radiance of the 185 and 254 nm lines in two positive column mercury discharge lamps was measured over a wide range of operating conditions. The lamps had internal diameters of 5 and 23 mm. Argon was used as a carrier gas. The lamps were operated with cold spot temperatures of 20, 40 and 60 0 C. At each of these temperatures, results were obtained for five currents ranging from 20 to 100 mA for the 5 mm lamp and from 200 to 1000 mA for the 23 mm lamp. For each current studied, results were determined for argon pressures ranging from 66.6 to 666 Pa (0.5 to 5.0 Torr) in the 5 mm lamp and 26.6 to 666 Pa (0.2 to 5.0 Torr) in the 23 mm lamp. An argon miniarc was used as the radiometric standard. By calibrating the spectral response of the optical system with a well-characterized mercury pencil lamp, results were obtained for 12 additional Hg lines from 289 to 579 nm. For the 23 mm lamp the electric field in the positive column was measured. For this lamp the radiated power as a percentage of input power was also determined. The results provide an experimental basis for validating computer models of Hg fluorescent lamp discharges

Far-IR measurements at Cerro Toco, Chile: FIRST, REFIR, and AERI

Science.gov (United States)

Cageao, Richard P.; Alford, J. Ashley; Johnson, David G.; Kratz, David P.; Mlynczak, Martin G.

2010-09-01

In mid-2009, the Radiative Heating in the Underexplored Bands Campaign II (RHUBC-II) was conducted from Cerro Toco, Chile, a high, dry, remote mountain plateau, 23°S , 67.8°W at 5.4km, in the Atacama Desert of Northern Chile. From this site, dominant IR water vapor absorption bands and continuum, saturated when viewed from the surface at lower altitudes, or in less dry locales, were investigated in detail, elucidating infrared (IR) absorption and emission in the atmosphere. Three Fourier Transform InfraRed (FTIR) instruments were at the site, the Far-Infrared Spectroscopy of the Troposphere (FIRST), the Radiation Explorer in the Far Infrared (REFIR), and the Atmospheric Emitted Radiance Interferometer (AERI). In a side-by-side comparison, these measured atmospheric downwelling radiation, with overlapping spectral coverage from 5 to 100μm (2000 to 100cm-1), and instrument spectral resolutions from 0.5 to 0.643cm-1, unapodized. In addition to the FTIR and other ground-based IR and microwave instrumentation, pressure/temperature/relative humidity measuring sondes, for atmospheric profiles to 18km, were launched from the site several times a day. The derived water vapor profiles, determined at times matching the FTIR measurement times, were used to model atmospheric radiative transfer. Comparison of instrument data, all at the same spectral resolution, and model calculations, are presented along with a technique for determining adjustments to line-by-line calculation continuum models. This was a major objective of the campaign.

Carbon dioxide /V2/ radiance results using a new nonequilibrium model

Science.gov (United States)

Sharma, R. D.; Nadile, R. M.

1981-01-01

It was observed during the SPIRE experiment (Spectral Infrared Rocket Experiment) that the 15 micron limb radiance stays constant from 95 to 110 km despite the fact that CO2 concentration over this altitude range decreases by a factor of 20. The results of a 15 micron CO2 radiance model are presented which explain the observed anomaly. It is shown that CO2 deactivation by oxygen is the predominant factor in 15 micron emission above 95 km.

Correction for reflected sky radiance in low-altitude coastal hyperspectral images.

Science.gov (United States)

Kim, Minsu; Park, Joong Yong; Kopilevich, Yuri; Tuell, Grady; Philpot, William

2013-11-10

Low-altitude coastal hyperspectral imagery is sensitive to reflections of sky radiance at the water surface. Even in the absence of sun glint, and for a calm water surface, the wide range of viewing angles may result in pronounced, low-frequency variations of the reflected sky radiance across the scan line depending on the solar position. The variation in reflected sky radiance can be obscured by strong high-spatial-frequency sun glint and at high altitude by path radiance. However, at low altitudes, the low-spatial-frequency sky radiance effect is frequently significant and is not removed effectively by the typical corrections for sun glint. The reflected sky radiance from the water surface observed by a low-altitude sensor can be modeled in the first approximation as the sum of multiple-scattered Rayleigh path radiance and the single-scattered direct-solar-beam radiance by the aerosol in the lower atmosphere. The path radiance from zenith to the half field of view (FOV) of a typical airborne spectroradiometer has relatively minimal variation and its reflected radiance to detector array results in a flat base. Therefore the along-track variation is mostly contributed by the forward single-scattered solar-beam radiance. The scattered solar-beam radiances arrive at the water surface with different incident angles. Thus the reflected radiance received at the detector array corresponds to a certain scattering angle, and its variation is most effectively parameterized using the downward scattering angle (DSA) of the solar beam. Computation of the DSA must account for the roll, pitch, and heading of the platform and the viewing geometry of the sensor along with the solar ephemeris. Once the DSA image is calculated, the near-infrared (NIR) radiance from selected water scan lines are compared, and a relationship between DSA and NIR radiance is derived. We then apply the relationship to the entire DSA image to create an NIR reference image. Using the NIR reference image

IR spectral analysis for the diagnostics of crust earthquake precursors

Directory of Open Access Journals (Sweden)

R. M. Umarkhodgaev

2012-11-01

Full Text Available Some possible physical processes are analysed that cause, under the condition of additional ionisation in a pre-breakdown electric field, emissions in the infrared (IR interval. The atmospheric transparency region of the IR spectrum at wavelengths of 7–15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH₄, CO₂, N₂O, NO₂, NO, and O₃. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analyzed. For daytime conditions, modifications of the adsorption spectra of the scattered solar emissions are studied; for nighttime, variations of emission spectra may be used for the analysis.

SPECTRAL RECONSTRUCTION BASED ON SVM FOR CROSS CALIBRATION

Directory of Open Access Journals (Sweden)

H. Gao

2017-05-01

Full Text Available Chinese HY-1C/1D satellites will use a 5nm/10nm-resolutional visible-near infrared(VNIR hyperspectral sensor with the solar calibrator to cross-calibrate with other sensors. The hyperspectral radiance data are composed of average radiance in the sensor’s passbands and bear a spectral smoothing effect, a transform from the hyperspectral radiance data to the 1-nm-resolution apparent spectral radiance by spectral reconstruction need to be implemented. In order to solve the problem of noise cumulation and deterioration after several times of iteration by the iterative algorithm, a novel regression method based on SVM is proposed, which can approach arbitrary complex non-linear relationship closely and provide with better generalization capability by learning. In the opinion of system, the relationship between the apparent radiance and equivalent radiance is nonlinear mapping introduced by spectral response function(SRF, SVM transform the low-dimensional non-linear question into high-dimensional linear question though kernel function, obtaining global optimal solution by virtue of quadratic form. The experiment is performed using 6S-simulated spectrums considering the SRF and SNR of the hyperspectral sensor, measured reflectance spectrums of water body and different atmosphere conditions. The contrastive result shows: firstly, the proposed method is with more reconstructed accuracy especially to the high-frequency signal; secondly, while the spectral resolution of the hyperspectral sensor reduces, the proposed method performs better than the iterative method; finally, the root mean square relative error(RMSRE which is used to evaluate the difference of the reconstructed spectrum and the real spectrum over the whole spectral range is calculated, it decreses by one time at least by proposed method.

Innovations in IR projector arrays

Science.gov (United States)

Cole, Barry E.; Higashi, B.; Ridley, Jeff A.; Holmen, J.; Newstrom, K.; Zins, C.; Nguyen, K.; Weeres, Steven R.; Johnson, Burgess R.; Stockbridge, Robert G.; Murrer, Robert Lee; Olson, Eric M.; Bergin, Thomas P.; Kircher, James R.; Flynn, David S.

2000-07-01

In the past year, Honeywell has developed a 512 X 512 snapshot scene projector containing pixels with very high radiance efficiency. The array can operate in both snapshot and raster mode. The array pixels have near black body characteristics, high radiance outputs, broad band performance, and high speed. IR measurements and performance of these pixels will be described. In addition, a vacuum probe station that makes it possible to select the best die for packaging and delivery based on wafer level radiance screening, has been developed and is in operation. This system, as well as other improvements, will be described. Finally, a review of the status of the present projectors and plans for future arrays is included.

Validation of the thermal code of RadTherm-IR, IR-Workbench, and F-TOM

Science.gov (United States)

Schwenger, Frédéric; Grossmann, Peter; Malaplate, Alain

2009-05-01

System assessment by image simulation requires synthetic scenarios that can be viewed by the device to be simulated. In addition to physical modeling of the camera, a reliable modeling of scene elements is necessary. Software products for modeling of target data in the IR should be capable of (i) predicting surface temperatures of scene elements over a long period of time and (ii) computing sensor views of the scenario. For such applications, FGAN-FOM acquired the software products RadTherm-IR (ThermoAnalytics Inc., Calumet, USA; IR-Workbench (OKTAL-SE, Toulouse, France). Inspection of the accuracy of simulation results by validation is necessary before using these products for applications. In the first step of validation, the performance of both "thermal solvers" was determined through comparison of the computed diurnal surface temperatures of a simple object with the corresponding values from measurements. CUBI is a rather simple geometric object with well known material parameters which makes it suitable for testing and validating object models in IR. It was used in this study as a test body. Comparison of calculated and measured surface temperature values will be presented, together with the results from the FGAN-FOM thermal object code F-TOM. In the second validation step, radiances of the simulated sensor views computed by RadTherm-IR and IR-Workbench will be compared with radiances retrieved from the recorded sensor images taken by the sensor that was simulated. Strengths and weaknesses of the models RadTherm-IR, IR-Workbench and F-TOM will be discussed.

Innovative monolithic detector for tri-spectral (THz, IR, Vis) imaging

Science.gov (United States)

Pocas, S.; Perenzoni, M.; Massari, N.; Simoens, F.; Meilhan, J.; Rabaud, W.; Martin, S.; Delplanque, B.; Imperinetti, P.; Goudon, V.; Vialle, C.; Arnaud, A.

2012-10-01

Fusion of multispectral images has been explored for many years for security and used in a number of commercial products. CEA-Leti and FBK have developed an innovative sensor technology that gathers monolithically on a unique focal plane arrays, pixels sensitive to radiation in three spectral ranges that are terahertz (THz), infrared (IR) and visible. This technology benefits of many assets for volume market: compactness, full CMOS compatibility on 200mm wafers, advanced functions of the CMOS read-out integrated circuit (ROIC), and operation at room temperature. The ROIC houses visible APS diodes while IR and THz detections are carried out by microbolometers collectively processed above the CMOS substrate. Standard IR bolometric microbridges (160x160 pixels) are surrounding antenna-coupled bolometers (32X32 pixels) built on a resonant cavity customized to THz sensing. This paper presents the different technological challenges achieved in this development and first electrical and sensitivity experimental tests.

RADIANCE AND PHOTON NOISE: Imaging in geometrical optics, physical optics, quantum optics and radiology.

Science.gov (United States)

Barrett, Harrison H; Myers, Kyle J; Caucci, Luca

2014-08-17

A fundamental way of describing a photon-limited imaging system is in terms of a Poisson random process in spatial, angular and wavelength variables. The mean of this random process is the spectral radiance. The principle of conservation of radiance then allows a full characterization of the noise in the image (conditional on viewing a specified object). To elucidate these connections, we first review the definitions and basic properties of radiance as defined in terms of geometrical optics, radiology, physical optics and quantum optics. The propagation and conservation laws for radiance in each of these domains are reviewed. Then we distinguish four categories of imaging detectors that all respond in some way to the incident radiance, including the new category of photon-processing detectors. The relation between the radiance and the statistical properties of the detector output is discussed and related to task-based measures of image quality and the information content of a single detected photon.

Experimental verification of active IR stealth technology by controlling the surface temperature using a thermoelectric element

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Geon; Han, Kuk Il; Choi, Jun Hyuk; Kim, Tae Kuk [Dept. of Mechanical Engineering, Chung Ang University, Seoul (Korea, Republic of)

2016-10-15

In this paper, we propose a technique for IR low-observability that uses an active IR signal tuning through the real time control of the object surface temperature according to the varying background environment. This is achieved by applying the proper object surface temperature obtained to result in the minimum radiance difference between the object and the background. Experimental verification by using the thermoelectric temperature control element shows that the IR radiance contrast between the object and the background can be reduced up to 99% during the night and up to 95% during the day time as compared to the un-tuned original radiance contrast values. The stealth technology demonstrated in this paper may be applied for many military systems needed for the IR stealth performance when a suitable temperature control unit is developed.

Experimental verification of active IR stealth technology by controlling the surface temperature using a thermoelectric element

International Nuclear Information System (INIS)

Kim, Dong Geon; Han, Kuk Il; Choi, Jun Hyuk; Kim, Tae Kuk

2016-01-01

In this paper, we propose a technique for IR low-observability that uses an active IR signal tuning through the real time control of the object surface temperature according to the varying background environment. This is achieved by applying the proper object surface temperature obtained to result in the minimum radiance difference between the object and the background. Experimental verification by using the thermoelectric temperature control element shows that the IR radiance contrast between the object and the background can be reduced up to 99% during the night and up to 95% during the day time as compared to the un-tuned original radiance contrast values. The stealth technology demonstrated in this paper may be applied for many military systems needed for the IR stealth performance when a suitable temperature control unit is developed

A comparison of measured radiances from AIRS and HIRS across different cloud types

Science.gov (United States)

Schreier, M. M.; Kahn, B. H.; Staten, P.

2015-12-01

The observation of Earth's atmosphere with passive remote sensing instruments is ongoing for decades and resulting in a long-term global dataset. Two prominent examples are operational satellite platforms from the National Oceanic and Atmospheric Administration (NOAA) or research platforms like NASA's Earth Observing System (EOS). The observed spectral ranges of these observations are often similar among the different platforms, but have large differences when it comes to resolution, accuracy and quality control. Our approach is to combine different kinds of instruments at the pixel-scale to improve the characterization of infrared radiances. We focus on data from the High-resolution Infrared Radiation Sounder (HIRS) and compare the observations to radiances from the Atmospheric Infrared Sounder (AIRS) on Aqua. The high spectral resolution of AIRS is used to characterize and possibly recalibrate the observed radiances from HIRS. Our approach is unique in that we use additional information from other passive instruments on the same platforms including the Advanced Very High Resolution Radiometer (AVHRR) and the MODerate resolution Imaging Spectroradiometer (MODIS). We will present comparisons of radiances from HIRS and AIRS within different types of clouds that are determined from the imagers. In this way, we can analyze and select the most homogeneous conditions for radiance comparisons and a possible re-calibration of HIRS. We hope to achieve a cloud-type-dependent calibration and quality control for HIRS, which can be extrapolated into the past via inter-calibration of the different HIRS instruments beyond the time of AIRS.

Identification of mineral compositions in some renal calculi by FT Raman and IR spectral analysis

Science.gov (United States)

Tonannavar, J.; Deshpande, Gouri; Yenagi, Jayashree; Patil, Siddanagouda B.; Patil, Nikhil A.; Mulimani, B. G.

2016-02-01

We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400 cm- 1) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH.

Identification of mineral compositions in some renal calculi by FT Raman and IR spectral analysis.

Science.gov (United States)

Tonannavar, J; Deshpande, Gouri; Yenagi, Jayashree; Patil, Siddanagouda B; Patil, Nikhil A; Mulimani, B G

2016-02-05

We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400c m(-1)) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH. Copyright © 2015 Elsevier B.V. All rights reserved.

On lamps, walls, and eyes: The spectral radiance field and the evaluation of light pollution indoors

Science.gov (United States)

Bará, Salvador; Escofet, Jaume

2018-01-01

Light plays a key role in the regulation of different physiological processes, through several visual and non-visual retinal phototransduction channels whose basic features are being unveiled by recent research. The growing body of evidence on the significance of these effects has sparked a renewed interest in the determination of the light field at the entrance pupil of the eye in indoor spaces. Since photic interactions are strongly wavelength-dependent, a significant effort is being devoted to assess the relative merits of the spectra of the different types of light sources available for use at home and in the workplace. The spectral content of the light reaching the observer eyes in indoor spaces, however, does not depend exclusively on the sources: it is partially modulated by the spectral reflectance of the walls and surrounding surfaces, through the multiple reflections of the light beams along all possible paths from the source to the observer. This modulation can modify significantly the non-visual photic inputs that would be produced by the lamps alone, and opens the way for controlling-to a certain extent-the subject's exposure to different regions of the optical spectrum. In this work we evaluate the expected magnitude of this effect and we show that, for factorizable sources, the spectral modulation can be conveniently described in terms of a set of effective filter-like functions that provide useful insights for lighting design and light pollution assessment. The radiance field also provides a suitable bridge between indoor and outdoor light pollution studies.

The Impact of Cross-track Infrared Sounder (CrIS) Cloud-Cleared Radiances on Hurricane Joaquin (2015) and Matthew (2016) Forecasts

Science.gov (United States)

Wang, Pei; Li, Jun; Li, Zhenglong; Lim, Agnes H. N.; Li, Jinlong; Schmit, Timothy J.; Goldberg, Mitchell D.

2017-12-01

Hyperspectral infrared (IR) sounders provide high vertical resolution atmospheric sounding information that can improve the forecast skill in numerical weather prediction. Commonly, only clear radiances are assimilated, because IR sounder observations are highly affected by clouds. A cloud-clearing (CC) technique, which removes the cloud effects from an IR cloudy field of view (FOV) and derives the cloud-cleared radiances (CCRs) or clear-sky equivalent radiances, can be an alternative yet effective way to take advantage of the thermodynamic information from cloudy skies in data assimilation. This study develops a Visible Infrared Imaging Radiometer Suite (VIIRS)-based CC method for deriving Cross-track Infrared Sounder (CrIS) CCRs under partially cloudy conditions. Due to the lack of absorption bands on VIIRS, two important quality control steps are implemented in the CC process. Validation using VIIRS clear radiances indicates that the CC method can effectively obtain the CrIS CCRs for FOVs with partial cloud cover. To compare the impacts from assimilation of CrIS original radiances and CCRs, three experiments are carried out on two storm cases, Hurricane Joaquin (2015) and Hurricane Matthew (2016), using Gridpoint Statistical Interpolation assimilation system and Weather Research and Forecasting-Advanced Research Version models. At the analysis time, more CrIS observations are assimilated when using CrIS CCRs than with CrIS original radiances. Comparing temperature, specific humidity, and U/V winds with radiosondes indicates that the data impacts are growing larger with longer time forecasts (beyond 72 h forecast). Hurricane track forecasts also show improvements from the assimilation of CrIS CCRs due to better weather system forecasts. The impacts of CCRs on intensity are basically neutral with mixed positive and negative results.

Background Radiance Estimation for Gas Plume Quantification for Airborne Hyperspectral Thermal Imaging

Directory of Open Access Journals (Sweden)

Ramzi Idoughi

2016-01-01

Full Text Available Hyperspectral imaging in the long-wave infrared (LWIR is a mean that is proving its worth in the characterization of gaseous effluent. Indeed the spectral and spatial resolution of acquisition instruments is steadily decreasing, making the gases characterization increasingly easy in the LWIR domain. The majority of literature algorithms exploit the plume contribution to the radiance corresponding to the difference of radiance between the plume-present and plume-absent pixels. Nevertheless, the off-plume radiance is unobservable using a single image. In this paper, we propose a new method to retrieve trace gas concentration from airborne infrared hyperspectral data. More particularly the outlined method improves the existing background radiance estimation approach to deal with heterogeneous scenes corresponding to industrial scenes. It consists in performing a classification of the scene and then applying a principal components analysis based method to estimate the background radiance on each cluster stemming from the classification. In order to determine the contribution of the classification to the background radiance estimation, we compared the two approaches on synthetic data and Telops Fourier Transform Spectrometer (FTS Imaging Hyper-Cam LW airborne acquisition above ethylene release. We finally show ethylene retrieved concentration map and estimate flow rate of the ethylene release.

TES Level 1 Algorithms: Interferogram Processing, Geolocation, Radiometric, and Spectral Calibration

Science.gov (United States)

Worden, Helen; Beer, Reinhard; Bowman, Kevin W.; Fisher, Brendan; Luo, Mingzhao; Rider, David; Sarkissian, Edwin; Tremblay, Denis; Zong, Jia

2006-01-01

The Tropospheric Emission Spectrometer (TES) on the Earth Observing System (EOS) Aura satellite measures the infrared radiance emitted by the Earth's surface and atmosphere using Fourier transform spectrometry. The measured interferograms are converted into geolocated, calibrated radiance spectra by the L1 (Level 1) processing, and are the inputs to L2 (Level 2) retrievals of atmospheric parameters, such as vertical profiles of trace gas abundance. We describe the algorithmic components of TES Level 1 processing, giving examples of the intermediate results and diagnostics that are necessary for creating TES L1 products. An assessment of noise-equivalent spectral radiance levels and current systematic errors is provided. As an initial validation of our spectral radiances, TES data are compared to the Atmospheric Infrared Sounder (AIRS) (on EOS Aqua), after accounting for spectral resolution differences by applying the AIRS spectral response function to the TES spectra. For the TES L1 nadir data products currently available, the agreement with AIRS is 1 K or better.

NOAA GOES-R Series Advanced Baseline Imager (ABI) Level 1b Radiances

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Advanced Baseline Imager (ABI) instrument samples the radiance of the Earth in sixteen spectral bands using several arrays of detectors in the instrument’s...

Constraining Cometary Crystal Shapes from IR Spectral Features

Science.gov (United States)

Wooden, D. H.; Lindsay, S.; Harker, D. E.; Kelley, M. S.; Woodward, C. E.; Murphy, J. R.

2013-12-01

A major challenge in deriving the silicate mineralogy of comets is ascertaining how the anisotropic nature of forsterite crystals affects the spectral features' wavelength, relative intensity, and asymmetry. Forsterite features are identified in cometary comae near 10, 11.05-11.2, 16, 19, 23.5, 27.5 and 33 μm [1-10], so accurate models for forsterite's absorption efficiency (Qabs) are a primary requirement to compute IR spectral energy distributions (SEDs, λFλ vs. λ) and constrain the silicate mineralogy of comets. Forsterite is an anisotropic crystal, with three crystallographic axes with distinct indices of refraction for the a-, b-, and c-axis. The shape of a forsterite crystal significantly affects its spectral features [13-16]. We need models that account for crystal shape. The IR absorption efficiencies of forsterite are computed using the discrete dipole approximation (DDA) code DDSCAT [11,12]. Starting from a fiducial crystal shape of a cube, we systematically elongate/reduce one of the crystallographic axes. Also, we elongate/reduce one axis while the lengths of the other two axes are slightly asymmetric (0.8:1.2). The most significant grain shape characteristic that affects the crystalline spectral features is the relative lengths of the crystallographic axes. The second significant grain shape characteristic is breaking the symmetry of all three axes [17]. Synthetic spectral energy distributions using seven crystal shape classes [17] are fit to the observed SED of comet C/1995 O1 (Hale-Bopp). The Hale-Bopp crystalline residual better matches equant, b-platelets, c-platelets, and b-columns spectral shape classes, while a-platelets, a-columns and c-columns worsen the spectral fits. Forsterite condensation and partial evaporation experiments demonstrate that environmental temperature and grain shape are connected [18-20]. Thus, grain shape is a potential probe for protoplanetary disk temperatures where the cometary crystalline forsterite formed. The

Predicting Top-of-Atmosphere Thermal Radiance Using MERRA-2 Atmospheric Data with Deep Learning

Directory of Open Access Journals (Sweden)

Tania Kleynhans

2017-11-01

Full Text Available Image data from space-borne thermal infrared (IR sensors are used for a variety of applications, however they are often limited by their temporal resolution (i.e., repeat coverage. To potentially increase the temporal availability of thermal image data, a study was performed to determine the extent to which thermal image data can be simulated from available atmospheric and surface data. The work conducted here explored the use of Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2 developed by The National Aeronautics and Space Administration (NASA to predict top-of-atmosphere (TOA thermal IR radiance globally at time scales finer than available satellite data. For this case study, TOA radiance data was derived for band 31 (10.97 μ m of the Moderate-Resolution Imaging Spectroradiometer (MODIS sensor. Two approaches have been followed, namely an atmospheric radiative transfer forward modeling approach and a supervised learning approach. The first approach uses forward modeling to predict TOA radiance from the available surface and atmospheric data. The second approach applied four different supervised learning algorithms to the atmospheric data. The algorithms included a linear least squares regression model, a non-linear support vector regression (SVR model, a multi-layer perceptron (MLP, and a convolutional neural network (CNN. This research found that the multi-layer perceptron model produced the lowest overall error rates with an root mean square error (RMSE of 1.36 W/m 2 ·sr· μ m when compared to actual Terra/MODIS band 31 image data. These studies found that for radiances above 6 W/m 2 ·sr· μ m, the forward modeling approach could predict TOA radiance to within 12 percent, and the best supervised learning approach can predict TOA to within 11 percent.

Nonuniformity correction of infrared cameras by reading radiance temperatures with a spatially nonhomogeneous radiation source

International Nuclear Information System (INIS)

Gutschwager, Berndt; Hollandt, Jörg

2017-01-01

We present a novel method of nonuniformity correction (NUC) of infrared cameras and focal plane arrays (FPA) in a wide optical spectral range by reading radiance temperatures and by applying a radiation source with an unknown and spatially nonhomogeneous radiance temperature distribution. The benefit of this novel method is that it works with the display and the calculation of radiance temperatures, it can be applied to radiation sources of arbitrary spatial radiance temperature distribution, and it only requires sufficient temporal stability of this distribution during the measurement process. In contrast to this method, an initially presented method described the calculation of NUC correction with the reading of monitored radiance values. Both methods are based on the recording of several (at least three) images of a radiation source and a purposeful row- and line-shift of these sequent images in relation to the first primary image. The mathematical procedure is explained in detail. Its numerical verification with a source of a predefined nonhomogeneous radiance temperature distribution and a thermal imager of a predefined nonuniform FPA responsivity is presented. (paper)

Spectral Distortion in Lossy Compression of Hyperspectral Data

Directory of Open Access Journals (Sweden)

Bruno Aiazzi

2012-01-01

Full Text Available Distortion allocation varying with wavelength in lossy compression of hyperspectral imagery is investigated, with the aim of minimizing the spectral distortion between original and decompressed data. The absolute angular error, or spectral angle mapper (SAM, is used to quantify spectral distortion, while radiometric distortions are measured by maximum absolute deviation (MAD for near-lossless methods, for example, differential pulse code modulation (DPCM, or mean-squared error (MSE for lossy methods, for example, spectral decorrelation followed by JPEG 2000. Two strategies of interband distortion allocation are compared: given a target average bit rate, distortion may be set to be constant with wavelength. Otherwise, it may be allocated proportionally to the noise level of each band, according to the virtually lossless protocol. Comparisons with the uncompressed originals show that the average SAM of radiance spectra is minimized by constant distortion allocation to radiance data. However, variable distortion allocation according to the virtually lossless protocol yields significantly lower SAM in case of reflectance spectra obtained from compressed radiance data, if compared with the constant distortion allocation at the same compression ratio.

Near-IR Spectral Imaging of Semiconductor Absorption Sites in Integrated Circuits

Directory of Open Access Journals (Sweden)

E. C. Samson

2004-12-01

Full Text Available We derive spectral maps of absorption sites in integrated circuits (ICs by varying the wavelength of the optical probe within the near-IR range. This method has allowed us to improve the contrast of the acquired images by revealing structures that have a different optical absorption from neighboring sites. A false color composite image from those acquired at different wavelengths is generated from which the response of each semiconductor structure can be deduced. With the aid of the spectral maps, nonuniform absorption was also observed in a semiconductor structure located near an electrical overstress defect. This method may prove important in failure analysis of ICs by uncovering areas exhibiting anomalous absorption, which could improve localization of defective edifices in the semiconductor parts of the microchip

Atmospheric emitted radiance interferometer (AERI): Status and the aerosol explanation for extra window region emissions

Energy Technology Data Exchange (ETDEWEB)

Revercomb, H.E.; Knuteson, R.O.; Best, F.A.; Dirkx, T.P. [Univ. of Wisconsin, Madison, WI (United States)] [and others

1996-04-01

High spectral resolution observations of downwelling emission from 3 to 19 microns have been made by the Atmospheric Emitted Radiance Interferometer (AERI) Prototype at the Southern Great Plains (SGP) Cloud and Radiative Testbed (CART) site for over two years. The spectral data set from AERI provides a basis for improving clear sky radiative transfer; determining the radiative impact of clouds, including the derivation of cloud radiative properties; defining the influences of aerosols in the window regions; and retrieving boundary layer state properties, including temperature, water vapor, and other trace gases. The data stream of radiometrically and spectrally calibrated radiances is routinely provided by Pacific Northwest Laboratory (PNL) to those science teams requesting it, and further information on the instrument and data characteristics is available in the ARM Science Team proceedings for 1993 and 1994 and in several conference publications. This paper describes the AERI status, calibration, field experiment wit a new AERI-01 and schedule, window region emissions, and future AERI plans.

Intercomparison of integrated IASI and AATSR calibrated radiances at 11 and 12 μm

Directory of Open Access Journals (Sweden)

R. J. Parker

2009-09-01

Full Text Available The mission objectives of the Infrared Atmospheric Sounding Interferometer (IASI are driven by the needs of the Numerical Weather Prediction (NWP and climate monitoring communities. These objectives rely upon the IASI instrument being able to measure top of atmosphere radiances accurately. This paper presents a technique and first results for the validation of the radiometric calibration of radiances for IASI, using a cross-calibration with the Advanced Along Track Scanning Radiometer (AATSR. The AATSR is able to measure Brightness Temperature (BT to an accuracy of 30 mK, and by applying the AATSR spectral filter functions to the IASI measured radiances we are able to compare AATSR and IASI Brightness Temperatures. By choosing coincident data points that are over the sea and in clear sky conditions, a threshold of homogeneity is derived. It is found that in these homogenous conditions, the IASI BTs agree with those measured by the AATSR to within 0.3 K, with an uncertainty of order 0.1 K. The agreement is particularly good at 11 μm where the difference is less than 0.1 K. These first results indicate that IASI is meeting its target objective of 0.5 K accuracy. It is believed that a refinement of the AATSR spectral filter functions will hopefully permit a tighter error constraint on the quality of the IASI data and hence further assessment of the climate quality of the radiances.

Sky radiance at a coastline and effects of land and ocean reflectivities

Science.gov (United States)

Kreuter, Axel; Blumthaler, Mario; Tiefengraber, Martin; Kift, Richard; Webb, Ann R.

2017-12-01

We present a unique case study of the spectral sky radiance distribution above a coastline. Results are shown from a measurement campaign in Italy involving three diode array spectroradiometers which are compared to 3-D model simulations from the Monte Carlo model MYSTIC. On the coast, the surrounding is split into two regions, a diffusely reflecting land surface and a water surface which features a highly anisotropic reflectance function. The reflectivities and hence the resulting radiances are a nontrivial function of solar zenith and azimuth angle and wavelength. We show that for low solar zenith angles (SZAs) around noon, the higher land albedo causes the sky radiance at 20° above the horizon to increase by 50 % in the near infrared at 850 nm for viewing directions towards the land with respect to the ocean. Comparing morning and afternoon radiances highlights the effect of the ocean's sun glint at high SZA, which contributes around 10 % to the measured radiance ratios. The model simulations generally agree with the measurements to better than 10 %. We investigate the individual effects of model input parameters representing land and ocean albedo and aerosols. Different land and ocean bi-directional reflectance functions (BRDFs) do not generally improve the model agreement. However, consideration of the uncertainties in the diurnal variation of aerosol optical depth can explain the remaining discrepancies between measurements and model. We further investigate the anisotropy effect of the ocean BRDF which is featured in the zenith radiances. Again, the uncertainty of the aerosol loading is dominant and obscures the modelled sun glint effect of 7 % at 650 nm. Finally, we show that the effect on the zenith radiance is restricted to a few kilometres from the coastline by model simulations along a perpendicular transect and by comparing the radiances at the coast to those measured at a site 15 km inland. Our findings are relevant to, for example, ground

Downwelling Far-Infrared Radiance Spectra Measured by FIRST at Cerro Toco, Chile

Science.gov (United States)

Mast, J. C.; Mlynczak, M. G.; Cageao, R.; Kratz, D. P.; Latvakoski, H.; Johnson, D. G.; Mlawer, E. J.; Turner, D. D.

2015-12-01

The Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument is a Fourier transform spectrometer developed by NASA Langley Research Center in collaboration with the Space Dynamics Laboratory and the Harvard-Smithsonian Center for Astrophysics. FIRST was initially developed for measuring the far-infrared portion of Earth's longwave spectrum as a balloon borne instrument and later was reconfigured to operate as a ground-based instrument. In its current ground-based configuration FIRST was deployed at 17500 ft on Cerro Toco, a mountain in the Atacama Desert of Chile, from August to October, 2009. There the integrated precipitable water (IPW) was as low as 0.02 cm. FIRST measurements from days with IPW between 0.024 and 0.035 cm during the campaign are presented here between 200 cm-1 and 800 cm-1. Significant spectral development in the far-IR is observed over the entire 200 cm-1 to 800 cm-1 band. Water vapor and temperature profiles from radiosonde and GVRP measurements are used as inputs to the AER Line-by-Line Radiative Transfer Model (LBLRTM) utilizing the AER v3.2 line parameter database. Uncertainties in both the measured and modeled radiances are accounted for in this study. The residual LBLRTM - FIRST is calculated to assess agreement between the measured and modeled spectra. Measured and model radiances generally agree to within the combined uncertainties for wavenumbers greater than 360 cm-1. At wavenumbers less than 360 cm-1 persistent troughs in the residual are present outside of the combined uncertainties. These features are present on different days and at different water vapor amounts. Possible solutions for these features are discussed.

The Light-Field of Microbenthic Communities - Radiance Distribution and Microscale Optics of Sandy Coastal Sediments Rid A-1977-2009

DEFF Research Database (Denmark)

KUHL, M.; JØRGENSEN, BB

1994-01-01

radiance distribution. Comparison of light fields in wet and dry quartz sand showed that the lower refractive index of air than of water caused a more forward-biased scattering in wet sand. Light penetration was therefore deeper and surface irradiance reflectance was lower in wet sand than in dry sand......The light field in coastal sediments was investigated at a spatial resolution of 0.2-0.5 mm by spectral measurements (450-850 nm) of field radiance and scalar irradiance using fiber-optic microprobes. Depth profiles of field radiance were measured with radiance microprobes at representative angles...... relative to vertically incident collimated light in rinsed quartz sand and in a coastal sandy sediment colonized by microalgae. Upwelling and downwelling components of irradiance and scalar irradiance were calculated from the radiance distributions. Calculated total scalar irradiance agreed well...

Comparing airborne and satellite retrievals of cloud optical thickness and particle effective radius using a spectral radiance ratio technique: two case studies for cirrus and deep convective clouds

Science.gov (United States)

Krisna, Trismono C.; Wendisch, Manfred; Ehrlich, André; Jäkel, Evelyn; Werner, Frank; Weigel, Ralf; Borrmann, Stephan; Mahnke, Christoph; Pöschl, Ulrich; Andreae, Meinrat O.; Voigt, Christiane; Machado, Luiz A. T.

2018-04-01

Solar radiation reflected by cirrus and deep convective clouds (DCCs) was measured by the Spectral Modular Airborne Radiation Measurement System (SMART) installed on the German High Altitude and Long Range Research Aircraft (HALO) during the Mid-Latitude Cirrus (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interaction and Dynamic of Convective Clouds System - Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modelling and to the Global Precipitation Measurement (ACRIDICON-CHUVA) campaigns. On particular flights, HALO performed measurements closely collocated with overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. A cirrus cloud located above liquid water clouds and a DCC topped by an anvil cirrus are analyzed in this paper. Based on the nadir spectral upward radiance measured above the two clouds, the optical thickness τ and particle effective radius reff of the cirrus and DCC are retrieved using a radiance ratio technique, which considers the cloud thermodynamic phase, the vertical profile of cloud microphysical properties, the presence of multilayer clouds, and the heterogeneity of the surface albedo. For the cirrus case, the comparison of τ and reff retrieved on the basis of SMART and MODIS measurements yields a normalized mean absolute deviation of up to 1.2 % for τ and 2.1 % for reff. For the DCC case, deviations of up to 3.6 % for τ and 6.2 % for reff are obtained. The larger deviations in the DCC case are mainly attributed to the fast cloud evolution and three-dimensional (3-D) radiative effects. Measurements of spectral upward radiance at near-infrared wavelengths are employed to investigate the vertical profile of reff in the cirrus. The retrieved values of reff are compared with corresponding in situ measurements using a vertical weighting method. Compared to the MODIS observations, measurements of SMART provide more information on the

Spectral gamuts and spectral gamut mapping

Science.gov (United States)

Rosen, Mitchell R.; Derhak, Maxim W.

2006-01-01

All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

Using MODIS spectral information to classify sea ice scenes for CERES radiance-to-flux inversion

Science.gov (United States)

Corbett, J.; Su, W.; Liang, L.; Eitzen, Z.

2013-12-01

The Clouds and Earth's Radiant Energy System (CERES) instruments on NASA's Terra and Aqua satellites measure the shortwave (SW) radiance reflected from the Earth. In order to provide an estimate of the top-of-atmosphere reflected SW flux we need to know the anisotropy of the radiance reflected from the scene. Sea Ice scenes are particularly complex due to the wide range of surface conditions that comprise sea ice. For example, the anisotropy of snow-covered sea ice is quite different to that of sea ice with melt-ponds. To attempt to provide a consistent scene classification we have developed the Sea Ice Brightness Index (SIBI). The SIBI is defined as one minus the normalized difference between reflectances from the 0.469 micron and 0.858 micron bands from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. For brighter snow-covered sea ice scenes the SIBI value is close to 1.0. As the surface changes to bare ice, melt ponds, etc. the SIBI decreases. For open water the SIBI value is around 0.2-0.3. The SIBI exhibits no dependence on viewing zenith or solar zenith angle, allowing for consistent scene identification. To use the SIBI we classify clear-sky CERES field-of-views over sea ice into 3 groups; SIBI≥0.935, 0.935>SIBI≥0.85 and SIBISIBI based ADMs. Using the second metric, we see a reduction in the latitude/longitude binned mean RMS error between the ADM predicted radiance and the measured radiance from 8% to 7% in May and from 17% to 12% in July. These improvements suggest that using the SIBI to account for changes in the sea ice surface will lead to improved CERES flux retrievals.

HYTHIRM Radiance Modeling and Image Analyses in Support of STS-119, STS-125 and STS-128 Space Shuttle Hypersonic Re-entries

Science.gov (United States)

Gibson, David M.; Spisz, Thomas S.; Taylor, Jeff C.; Zalameda, Joseph N.; Horvath, Thomas J.; Tomek, Deborah M.; Tietjen, Alan B.; Tack, Steve; Bush, Brett C.

2010-01-01

We provide the first geometrically accurate (i.e., 3-D) temperature maps of the entire windward surface of the Space Shuttle during hypersonic reentry. To accomplish this task we began with estimated surface temperatures derived from CFD models at integral high Mach numbers and used them, the Shuttle's surface properties and reasonable estimates of the sensor-to-target geometry to predict the emitted spectral radiance from the surface (in units of W sr-1 m-2 nm-1). These data were converted to sensor counts using properties of the sensor (e.g. aperture, spectral band, and various efficiencies), the expected background, and the atmosphere transmission to inform the optimal settings for the near-infrared and midwave IR cameras on the Cast Glance aircraft. Once these data were collected, calibrated, edited, registered and co-added we formed both 2-D maps of the scene in the above units and 3-D maps of the bottom surface in temperature that could be compared with not only the initial inputs but also thermocouple data from the Shuttle itself. The 3-D temperature mapping process was based on the initial radiance modeling process. Here temperatures were guessed for each node in a well-resolved 3-D framework, a radiance model was produced and compared to the processed imagery, and corrections to the temperature were estimated until the iterative process converged. This process did very well in characterizing the temperature structure of the large asymmetric boundary layer transition the covered much of the starboard bottom surface of STS-119 Discovery. Both internally estimated accuracies and differences with CFD models and thermocouple measurements are at most a few percent. The technique did less well characterizing the temperature structure of the turbulent wedge behind the trip due to limitations in understanding the true sensor resolution. (Note: Those less inclined to read the entire paper are encouraged to read an Executive Summary provided at the end.)

Platform and Environmental Effects on Above- and In-Water Determinations of Water-Leaving Radiances

Science.gov (United States)

Hooker, Stanford B.; Morel, Andre; McClain, Charles R. (Technical Monitor)

2001-01-01

A comparison of above- and in-water spectral measurements in Case-1 conditions showed the uncertainty in above-water determinations of water-leaving radiances depended on the pointing angle of the above-water instruments with respect to the side of the ship. Two above-water methods were used to create a diagnostic variable to quantify the presence of superstructure reflections which degraded the above-water intracomparisons of water-leaving radiances by 10.9-33.4% (for far-to-near viewing distances, respectively). The primary conclusions of the above- and in-water intercomparison of water-leaving radiances were as follows: a) the SeaWiFS 5% radiometric objective was achieved with the above-water approach, but reliably with only one method and only for about half the data; b) a decrease in water-leaving radiance values was seen in the presence of swell, although, wave crests were radiometrically brighter than the troughs; and c) standard band ratios used in ocean color algorithms remained severely affected, because of the relatively low signal and, thus, proportionally significant contamination at the 555nm wavelength.

IR spectral analysis for the diagnostics of crust earthquake precursors

Science.gov (United States)

Umarkhodgaev, R. M.; Liperovsky, V. A.; Mikhailin, V. V.; Meister, C.-V.; Naumov, D. Ju

2012-04-01

In regions of future earthquakes, a few days before the seismic shock, the emanation of radon and hydrogen is being observed, which causes clouds of increased ionisation in the atmosphere. In the present work the possible diagnostics of these clouds using infrared (IR) spectroscopy is considered, which may be important and useful for the general geophysical system of earthquake prediction and the observation of industrial emissions of radioactive materials into the atmosphere. Some possible physical processes are analysed, which cause, under the condition of additional ionisation in a pre-breakdown electrical field, emissions in the IR interval. In doing so, the transparency region of the IR spectrum at wavelengths of 7-15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH4, CO2, N2O, NO2, NO, and O3. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analysed. The laboratory equipment for the investigation of the IR absorption spectrum is constructed for the cases of normal and decreased atmospheric pressures. The syntheses of ozone and nitrous oxides are performed in the barrier discharge. It is studied if the products of the syntheses may be used to model atmospheric processes where these components take part. Spectra of products of the syntheses in the wavelength region of 2-10 μm are observed and analysed. A device is created for the syntheses and accumulation of nitrous oxides. Experiments to observe the IR-spectra of ozone and nitrous oxides during the syntheses and during the further evolution of these molecules are performed. For the earthquake prediction, practically, the investigation of emission spectra is most important, but during the laboratory experiments, the radiation of the excited molecules is shifted by a

Sky radiance at a coastline and effects of land and ocean reflectivities

Directory of Open Access Journals (Sweden)

A. Kreuter

2017-12-01

Full Text Available We present a unique case study of the spectral sky radiance distribution above a coastline. Results are shown from a measurement campaign in Italy involving three diode array spectroradiometers which are compared to 3-D model simulations from the Monte Carlo model MYSTIC. On the coast, the surrounding is split into two regions, a diffusely reflecting land surface and a water surface which features a highly anisotropic reflectance function. The reflectivities and hence the resulting radiances are a nontrivial function of solar zenith and azimuth angle and wavelength. We show that for low solar zenith angles (SZAs around noon, the higher land albedo causes the sky radiance at 20° above the horizon to increase by 50 % in the near infrared at 850 nm for viewing directions towards the land with respect to the ocean. Comparing morning and afternoon radiances highlights the effect of the ocean's sun glint at high SZA, which contributes around 10 % to the measured radiance ratios. The model simulations generally agree with the measurements to better than 10 %. We investigate the individual effects of model input parameters representing land and ocean albedo and aerosols. Different land and ocean bi-directional reflectance functions (BRDFs do not generally improve the model agreement. However, consideration of the uncertainties in the diurnal variation of aerosol optical depth can explain the remaining discrepancies between measurements and model. We further investigate the anisotropy effect of the ocean BRDF which is featured in the zenith radiances. Again, the uncertainty of the aerosol loading is dominant and obscures the modelled sun glint effect of 7 % at 650 nm. Finally, we show that the effect on the zenith radiance is restricted to a few kilometres from the coastline by model simulations along a perpendicular transect and by comparing the radiances at the coast to those measured at a site 15 km inland. Our findings are relevant to

An overview of surface radiance and biology studies in FIFE

Science.gov (United States)

Blad, B. L.; Schimel, D. S.

1992-11-01

The use of satellite data to study and to understand energy and mass exchanges between the land surface and the atmosphere requires information about various biological processes and how various reflected or emitted spectral radiances are influenced by or manifested in these processes. To obtain such information, studies were conducted by the First ISLSCP Field Experiment (FIFE) surface radiances and biology (SRB) group using surface, near-surface, helicopter, and aircraft measurements. The two primary objectives of this group were to relate radiative fluxes to biophysical parameters and physiological processes and to assess how various management treatments affect important biological processes. This overview paper summarizes the results obtained by various SRB teams working in nine different areas: (1) measurement of bidirectional reflectance and estimation of hemispherical albedo; (2) evaluation of spatial and seasonal variability of spectral reflectance and vegetation indices; (3) determination of surface and radiational factors and their effects on vegetation indices and PAR relationships; (4) use of surface temperatures to estimate sensible heat flux; (5) controls over photosynthesis and respiration at small scales; (6) soil surface CO2 fluxes and grassland carbon budget; (7) landscape variations in controls over gas exchange and energy partitioning; (8) radiometric response of prairie to management and topography; and (9) determination of nitrogen gas exchanges in a tallgrass prairie.

Spectral Confirmation of New Galactic LBV and WN Stars Associated With Mid-IR Nebulae

Science.gov (United States)

Stringfellow, Guy; Gvaramadze, Vasilii V.

2014-08-01

Luminous Blue Variable (LBV) stars represent an extremely rare class and short-lived phase in the lives of very luminous massive stars with high mass loss rates. Extragalactic LBVs are responsible for producing false supernovae (SN), the SN Impostors, and have been directly linked with the progenitors of actual SN, indicating the LBV phase can be a final endpoint for massive star evolution. Yet only a few confirmed LBVs have been identified in the Galaxy. Their stellar evolution is poorly constrained by observations, and the physical reason for their unstable nature, both in terms of moderate spectral and photometric variability of a few magnitudes and the giant eruptions a la η Car that rival SN explosions, remains a mystery. Newly discovered mid-IR shells act as signposts, pointing to the central massive stars (LBV and Wolf-Rayet [WR] stars) that produced them. We have undertaken a spectroscopic survey of possible progenitor stars within these shells and are discovering that many are LBVs and WN-type WR transitional stars. We propose to extend this IR spectral survey to the south to search for new progenitor stars associated with dozens of newly identified shells. This survey should result in a substantial increase of new WRs and candidate LBVs for continued future study. Spectral analysis will yield new insights into the winds and physical properties of these rare and important objects, and lead to a better understanding of the physics driving giant eruptions.

Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

OpenAIRE

M. L. Belov; V. A. Gorodnichev; D. A. Kravtsov; A. A. Cherpakova

2016-01-01

The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m) and near-IR (~ 1.54 and ~ 2 m) spectral bands from the point of view of recorded lidar signal value to ful...

Solar Radius Determination from Sodism/Picard and HMI/SDO Observations of the Decrease of the Spectral Solar Radiance during the 2012 June Venus Transit

Science.gov (United States)

Hauchecorne, A.; Meftah, M.; Irbah, A.; Couvidat, S.; Bush, R.; Hochedez, J.-F.

2014-03-01

On 2012 June 5-6, the transit of Venus provided a rare opportunity to determine the radius of the Sun using solar imagers observing a well-defined object, namely, the planet and its atmosphere, partially occulting the Sun. A new method has been developed to estimate the solar radius during a planetary transit. It is based on the estimation of the spectral solar radiance decrease in a region around the contact between the planet and the Sun at the beginning of the ingress and at the end of the egress. The extrapolation to zero of the radiance decrease versus the Sun-to-Venus apparent angular distance allows estimation of the solar radius at the time of first and fourth contacts. This method presents the advantage of being almost independent on the plate scale, the distortion, the refraction by the planetary atmosphere, and on the point-spread function of the imager. It has been applied to two space solar visible imagers, SODISM/PICARD and HMI/SDO. The found results are mutually consistent, despite their different error budgets: 959.''85 ± 0.''19 (1σ) for SODISM at 607.1 nm and 959.''90 ± 0.''06 (1σ) for HMI at 617.3 nm.

Solar radius determination from SODISM/PICARD and HMI/SDO observations of the decrease of the spectral solar radiance during the 2012 June Venus transit

International Nuclear Information System (INIS)

Hauchecorne, A.; Meftah, M.; Irbah, A.; Hochedez, J.-F.; Couvidat, S.; Bush, R.

2014-01-01

On 2012 June 5-6, the transit of Venus provided a rare opportunity to determine the radius of the Sun using solar imagers observing a well-defined object, namely, the planet and its atmosphere, partially occulting the Sun. A new method has been developed to estimate the solar radius during a planetary transit. It is based on the estimation of the spectral solar radiance decrease in a region around the contact between the planet and the Sun at the beginning of the ingress and at the end of the egress. The extrapolation to zero of the radiance decrease versus the Sun-to-Venus apparent angular distance allows estimation of the solar radius at the time of first and fourth contacts. This method presents the advantage of being almost independent on the plate scale, the distortion, the refraction by the planetary atmosphere, and on the point-spread function of the imager. It has been applied to two space solar visible imagers, SODISM/PICARD and HMI/SDO. The found results are mutually consistent, despite their different error budgets: 959.''85 ± 0.''19 (1σ) for SODISM at 607.1 nm and 959.''90 ± 0.''06 (1σ) for HMI at 617.3 nm.

Similarity maps and hierarchical clustering for annotating FT-IR spectral images.

Science.gov (United States)

Zhong, Qiaoyong; Yang, Chen; Großerüschkamp, Frederik; Kallenbach-Thieltges, Angela; Serocka, Peter; Gerwert, Klaus; Mosig, Axel

2013-11-20

Unsupervised segmentation of multi-spectral images plays an important role in annotating infrared microscopic images and is an essential step in label-free spectral histopathology. In this context, diverse clustering approaches have been utilized and evaluated in order to achieve segmentations of Fourier Transform Infrared (FT-IR) microscopic images that agree with histopathological characterization. We introduce so-called interactive similarity maps as an alternative annotation strategy for annotating infrared microscopic images. We demonstrate that segmentations obtained from interactive similarity maps lead to similarly accurate segmentations as segmentations obtained from conventionally used hierarchical clustering approaches. In order to perform this comparison on quantitative grounds, we provide a scheme that allows to identify non-horizontal cuts in dendrograms. This yields a validation scheme for hierarchical clustering approaches commonly used in infrared microscopy. We demonstrate that interactive similarity maps may identify more accurate segmentations than hierarchical clustering based approaches, and thus are a viable and due to their interactive nature attractive alternative to hierarchical clustering. Our validation scheme furthermore shows that performance of hierarchical two-means is comparable to the traditionally used Ward's clustering. As the former is much more efficient in time and memory, our results suggest another less resource demanding alternative for annotating large spectral images.

Detection and classification of salmonella serotypes using spectral signatures collected by fourier transform infrared (FT-IR) spectroscopy

Science.gov (United States)

Spectral signatures of Salmonella serotypes namely Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky were collected using Fourier transform infrared spectroscopy (FT-IR). About 5-10 µL of Salmonella suspensions with concentrations of 1...

Release path temperatures of shock-compressed tin from dynamic reflectance and radiance measurements

Energy Technology Data Exchange (ETDEWEB)

La Lone, B. M., E-mail: lalonebm@nv.doe.gov; Stevens, G. D.; Turley, W. D. [National Security Technologies, LLC, Special Technologies Laboratory, Santa Barbara, California 93111 (United States); Holtkamp, D. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Iverson, A. J. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States); Hixson, R. S.; Veeser, L. R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

2013-08-14

Dynamic reflectance and radiance measurements were conducted for tin samples shock compressed to 35 GPa and released to 15 GPa using high explosives. We determined the reflectance of the tin samples glued to lithium fluoride windows using an integrating sphere with an internal xenon flashlamp as an illumination source. The dynamic reflectance (R) was determined at near normal incidence in four spectral bands with coverage in visible and near-infrared spectra. Uncertainties in R/R{sub 0} are <2%, and uncertainties in absolute reflectance are <5%. In complementary experiments, thermal radiance from the tin/glue/lithium fluoride interface was recorded with similar shock stress and spectral coverage as the reflectance measurements. The two sets of experiments were combined to obtain the temperature history of the tin surface with an uncertainty of <2%. The stress at the interface was determined from photonic Doppler velocimetry and combined with the temperatures to obtain temperature-stress release paths for tin. We discuss the relationship between the experimental release paths and release isentropes that begin on the principal shock Hugoniot.

IR characteristic simulation of city scenes based on radiosity model

Science.gov (United States)

Xiong, Xixian; Zhou, Fugen; Bai, Xiangzhi; Yu, Xiyu

2013-09-01

Reliable modeling for thermal infrared (IR) signatures of real-world city scenes is required for signature management of civil and military platforms. Traditional modeling methods generally assume that scene objects are individual entities during the physical processes occurring in infrared range. However, in reality, the physical scene involves convective and conductive interactions between objects as well as the radiations interactions between objects. A method based on radiosity model describes these complex effects. It has been developed to enable an accurate simulation for the radiance distribution of the city scenes. Firstly, the physical processes affecting the IR characteristic of city scenes were described. Secondly, heat balance equations were formed on the basis of combining the atmospheric conditions, shadow maps and the geometry of scene. Finally, finite difference method was used to calculate the kinetic temperature of object surface. A radiosity model was introduced to describe the scattering effect of radiation between surface elements in the scene. By the synthesis of objects radiance distribution in infrared range, we could obtain the IR characteristic of scene. Real infrared images and model predictions were shown and compared. The results demonstrate that this method can realistically simulate the IR characteristic of city scenes. It effectively displays the infrared shadow effects and the radiation interactions between objects in city scenes.

Infrared spectroscopy (2.3-20 microns) for the geological interpretation of remotely-sensed multispectral thermal infrared data

Science.gov (United States)

Bartholomew, Mary Jane; Kahle, Anne B.; Hoover, Gordon

1989-01-01

The spectral radiance and spectral reflectance of natural weathered surfaces of common sedimentary and igneous rocks is determined from in situ and in the laboratory measurements. In situ spectral radiance measurements (5-14 microns) were made with a portable spectral radiometer and were used to derive the spectral emissivity of the rocks. The spectral reflectance measurements (2.3-20 microns) were made in a laboratory with a Fourier transform IR spectrometer with a diffuse reflectance accessory. Good agreement is found between the two techniques. The field portable spectrometer has a larger field of view and the in situ data provide more accurate measurements of the intensity of spectral features related to temperature and atmospheric effects.

Improving Forecast Skill by Assimilation of AIRS Cloud Cleared Radiances RiCC

Science.gov (United States)

Susskind, Joel; Rosenberg, Robert I.; Iredell, Lena

2015-01-01

ECMWF, NCEP, and GMAO routinely assimilate radiosonde and other in-situ observations along with satellite IR and MW Sounder radiance observations. NCEP and GMAO use the NCEP GSI Data Assimilation System (DAS).GSI DAS assimilates AIRS, CrIS, IASI channel radiances Ri on a channel-by-channel, case-by-case basis, only for those channels i thought to be unaffected by cloud cover. This test excludes Ri for most tropospheric sounding channels under partial cloud cover conditions. AIRS Version-6 RiCC is a derived quantity representative of what AIRS channel i would have seen if the AIRS FOR were cloud free. All values of RiCC have case-by-case error estimates RiCC associated with them. Our experiments present to the GSI QCd values of AIRS RiCC in place of AIRS Ri observations. GSI DAS assimilates only those values of RiCC it thinks are cloud free. This potentially allows for better coverage of assimilated QCd values of RiCC as compared to Ri.

Cloud and radiance measurements with the VIS/NIR Daylight Whole Sky Imager at Lindenberg (Germany)

Energy Technology Data Exchange (ETDEWEB)

Feister, U. [Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg (Germany); Shields, J. [Scripps Inst. of Oceanography, Univ. of California, San Diego (United States)

2005-10-01

Ground-based cloud data acquired with the whole sky imager (WSI) are analyzed in relation to measurements of solar radiation performed at the Lindenberg Meteorological Observatory. Cloud fractions derived by the cloud detection algorithm from WSI images acquired during daylight hours between 2002 and 2004 are compared with conventional cloud observations for the two sites Potsdam and Lindenberg, and also with ceilometer data of cloud-base heights at Lindenberg. The comparison statistics are discussed in the context of different principles of measurement. A few case studies illustrate the strong scattering effect of clouds on solar radiance and irradiance measured at the ground in different spectral regions. Particularly clouds close to the apparent position of the sun lead to strong enhancements of solar diffuse irradiance incident on horizontal planes and hemispheres that substantially exceed corresponding clear-sky values. Irradiances derived from WSI sky radiance fields are shown in comparison to pyranometer data of diffuse irradiance and radiative transfer model calculations performed for clear sky conditions. Examples of spectral sky radiances with moving contrails illustrate the significant enhancement the contrails have compared to clear sky, even though they may have a relatively small direct effect on global irradiance values. As contrails are observed at Lindenberg for about 18 to 19% of daylight hours, and part of them become clouds, the indirect impact of these changes on solar irradiance received at the ground may not be negligible. (orig.)

Web-based Data Exploration, Exploitation and Visualization Tools for Satellite Sensor VIS/IR Calibration Applications

Science.gov (United States)

Gopalan, A.; Doelling, D. R.; Scarino, B. R.; Chee, T.; Haney, C.; Bhatt, R.

2016-12-01

The CERES calibration group at NASA/LaRC has developed and deployed a suite of online data exploration and visualization tools targeted towards a range of spaceborne VIS/IR imager calibration applications for the Earth Science community. These web-based tools are driven by the open-source R (Language for Statistical Computing and Visualization) with a web interface for the user to customize the results according to their application. The tool contains a library of geostationary and sun-synchronous imager spectral response functions (SRF), incoming solar spectra, SCIAMACHY and Hyperion Earth reflected visible hyper-spectral data, and IASI IR hyper-spectral data. The suite of six specific web-based tools was designed to provide critical information necessary for sensor cross-calibration. One of the challenges of sensor cross-calibration is accounting for spectral band differences and may introduce biases if not handled properly. The spectral band adjustment factors (SBAF) are a function of the earth target, atmospheric and cloud conditions or scene type and angular conditions, when obtaining sensor radiance pairs. The SBAF will need to be customized for each inter-calibration target and sensor pair. The advantages of having a community open source tool are: 1) only one archive of SCIAMACHY, Hyperion, and IASI datasets needs to be maintained, which is on the order of 50TB. 2) the framework will allow easy incorporation of new satellite SRFs and hyper-spectral datasets and associated coincident atmospheric and cloud properties, such as PW. 3) web tool or SBAF algorithm improvements or suggestions when incorporated can benefit the community at large. 4) The customization effort is on the user rather than on the host. In this paper we discuss each of these tools in detail and explore the variety of advanced options that can be used to constrain the results along with specific use cases to highlight the value-added by these datasets.

Radical protection by differently composed creams in the UV/VIS and IR spectral ranges.

Science.gov (United States)

Meinke, Martina C; Syring, Felicia; Schanzer, Sabine; Haag, Stefan F; Graf, Rüdiger; Loch, Manuela; Gersonde, Ingo; Groth, Norbert; Pflücker, Frank; Lademann, Jürgen

2013-01-01

Modern sunscreens are well suited to provide sufficient protection in the UV range because the filter substances absorb or scatter UV radiation. Although up to 50% of radicals are formed in the visible and infrared spectral range during solar radiation protection strategies are not provided in this range. Previous investigations of commercially available products have shown that in addition to physical filters, antioxidants (AO) are necessary to provide protective effects in the infrared range by neutralizing already formed radicals. In this study, the efficacy of filter substances and AO to reduce radical formation in both spectral ranges was investigated after UV/VIS or IR irradiation. Optical properties and radical protection were determined for the investigated creams. It was found that organic UV filters lower radical formation in the UV/VIS range to 35% compared to untreated skin, independent of the presence of AO. Further reduction to 14% was reached by addition of 2% physical filters, whereas physical filters alone were ineffective in the UV/VIS range due to the low concentration. In contrast, this filter type reduced radical formation in the IR range significantly to 65%; similar effects were aroused after application of AO. Sunscreens which contain organic UV filters, physical filters and AO ensure protection in the complete solar spectrum. © 2013 The American Society of Photobiology.

Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

Directory of Open Access Journals (Sweden)

M. L. Belov

2016-01-01

Full Text Available The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m and near-IR (~ 1.54 and ~ 2 m spectral bands from the point of view of recorded lidar signal value to fulfill the tasks of laser sensing the natural formations and laser aerosol sensing in the atmosphere.It is shown that the remote sensing lasers with appropriate characteristics can be selected both in the UV band (at a wavelength of 0.355 μm and in the near-IR band (at wavelengths of 1.54 ~ or ~ 2 μm.Molecular scattering has its maximum (for the selected wavelength at a wavelength of 0.355 μm in the UV band, and the minimum at the wavelengths of 1.54 and 2.09 μm in the near -IR band. The main contribution to the molecular absorption at a wavelength of 0.355 μm is made by ozone. In the near-IR spectral band the radiation is absorbed due to water vapor and carbon dioxide.Calculations show that the total effect of the molecular absorption and scattering has no influence on radiation transmission for both the wavelength of 0.355 μm in the UV band, and the wavelengths of 1.54 and 2.09 μm in the near-IR band for sensing trails ~ 1 km.One of the main factors of laser radiation attenuation in the Earth's atmosphere is radiation scattering by aerosol particles.The results of calculations at wavelengths of 0.355 μm, 1.54 μm and 2.09 μm for the several models of the atmosphere show that a choice of the most effective (in terms of the recorded signal of lidar and eye-safe radiation wavelength depends strongly on the task of sensing.To fulfill the task of laser sensing the natural formations, among the eye-safe wavelengths there is one significantly advantageous

Aerosol Properties Derived from Airborne Sky Radiance and Direct Beam Measurements in Recent NASA and DoE Field Campaigns

Science.gov (United States)

Redemann, J.; Flynn, C. J.; Shinozuka, Y.; Russell, P. B.; Kacenelenbogen, M.; Segal-Rosenheimer, M.; Livingston, J. M.; Schmid, B.; Dunagan, S. E.; Johnson, R. R.;

EPR and IR spectral investigations on some leafy vegetables of Indian origin

Science.gov (United States)

Prasuna, C. P. Lakshmi; Chakradhar, R. P. S.; Rao, J. L.; Gopal, N. O.

2009-09-01

EPR spectral investigations have been carried out on four edible leafy vegetables of India, which are used as dietary component in day to day life. In Rumex vesicarius leaf sample, EPR spectral investigations at different temperatures indicate the presence of anti-ferromagnetically coupled Mn(IV)-Mn(IV) complexes. EPR spectra of Trigonella foenum graecum show the presence of Mn ions in multivalent state and Fe 3+ ions in rhombic symmetry. EPR spectra of Basella rubra indicate the presence of Mn(IV)-O-Mn(IV) type complexes. The EPR spectra of Basella rubra have been studied at different temperatures. It is found that the spin population for the resonance signal at g = 2.06 obeys the Boltzmann distribution law. The EPR spectra of Moringa oliefera leaves show the presence of Mn 2+ ions. Radiation induced changes in free radical of this sample have also been studied. The FT-IR spectra of Basella rubra and Moringa oliefera leaves show the evidences for the protein matrix bands and those corresponding to carboxylic C dbnd O bonds.

Assimilating All-Sky Himawari-8 Satellite Infrared Radiances: A Case of Typhoon Soudelor (2015)

OpenAIRE

Honda, Takumi; Miyoshi, Takemasa; Lien, Guo-Yuan; Nishizawa, Seiya; Yoshida, Ryuji; Adachi, Sachiho A.; Terasaki, Koji; Okamoto, Kozo; Tomita, Hirofumi; Bessho, Kotaro

2018-01-01

Japan’s new geostationary satellite Himawari-8, the first of a series of the third-generation geostationary meteorological satellites includingGOES-16, has been operational since July 2015. Himawari-8 produces highresolution observations with 16 frequency bands every 10 min for full disk, and every 2.5 min for local regions. This study aims to assimilate all-sky every-10-min infrared (IR) radiances from Himawari-8 with a regional numerical weather prediction model and to investigate its impac...

Measured and Modeled Downwelling Far-Infrared Radiances in Very Dry Environments and Calibration Requirements for Future Experiments

Science.gov (United States)

Mast, J. C.; Mlynczak, M. G.; Cageao, R.; Kratz, D. P.; Latvakoski, H.; Johnson, D. G.; Mlawer, E. J.; Turner, D. D.

2016-12-01

Downwelling radiances measured by the Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument in an environment with integrated precipitable water as low as 0.03 cm are compared with calculated spectra in the far-infrared and mid-infrared. In its current ground-based configuration FIRST was deployed to 5.38 km on Cerro Toco, a mountain in the Atacama Desert of Chile, from August to October 2009. There FIRST took part in the Radiative Heating in Unexplored Bands Campaign Part 2. Water vapor and temperature profiles from an optimal-estimation-based physical retrieval algorithm (using simultaneous radiosonde and multichannel 183 GHz microwave radiometer measurements) are input to the AER Line-by-Line Radiative Transfer Model (LBLRTM) to compute radiances for comparison with FIRST. The AER v3.4 line parameter database is used. The low water vapor amounts and relatively cold atmosphere result in extremely small far-IR radiances (1.5 mW/m2/sr/cm-1) with corresponding brightness temperatures of 120 K. The residual LBLRTM minus FIRST is calculated to assess agreement between the measured and modeled spectra. Uncertainties in both the measured and modeled radiances are accounted for in the comparison. A goal of the deployment and subsequent analysis is the assessment of water vapor spectroscopy in the far-infrared and mid-infrared. While agreement is found between measured and modeled radiances within the combined uncertainties across all spectra, uncertainties in the measured water vapor profiles and from the laboratory calibration exceed those associated with water vapor spectroscopy in this very low radiance environment. Consequently, no improvement in water vapor spectroscopy is afforded by these measurements. However, we use these results to place requirements on instrument calibration accuracy and water vapor profile accuracy for future campaigns to similarly dry environments. Instrument calibration uncertainty needs to be at 2% (1-sigma) of measured radiance

Method of forming half-tone test images in the IR spectrum

International Nuclear Information System (INIS)

Glebova, L.N.; Gridin, A.S.; Denisov, V.N.; Dmitriev, I.Yu.; Mochalov, I.V.; Chebotarev, S.A.

1992-01-01

Test charts in the form of half-tone IR images, including not only an image of the interference-producing background (the underlying earth's surface and clouds), but also the observation objects, are required for conducting bench tests on the noise immunity of modern optoelectronic equipment designed to solve observation problems under background-interference conditions. The simulation of extended half-tone IR images containing the high spatial frequencies of background formations having an appreciable dynamic range of reproducible radiances is a complex problem in technical and processing aspects. The use of phosphorus as visible-to-IR converters for the creation of IR-background simulators is shown to be possible in principle in this paper. 2 refs., 3 figs

Nonlocal Coulomb correlations in pure and electron-doped Sr2IrO4 : Spectral functions, Fermi surface, and pseudo-gap-like spectral weight distributions from oriented cluster dynamical mean-field theory

Science.gov (United States)

Martins, Cyril; Lenz, Benjamin; Perfetti, Luca; Brouet, Veronique; Bertran, François; Biermann, Silke

2018-03-01

We address the role of nonlocal Coulomb correlations and short-range magnetic fluctuations in the high-temperature phase of Sr2IrO4 within state-of-the-art spectroscopic and first-principles theoretical methods. Introducing an "oriented-cluster dynamical mean-field scheme", we compute momentum-resolved spectral functions, which we find to be in excellent agreement with angle-resolved photoemission spectra. We show that while short-range antiferromagnetic fluctuations are crucial to accounting for the electronic properties of Sr2IrO4 even in the high-temperature paramagnetic phase, long-range magnetic order is not a necessary ingredient of the insulating state. Upon doping, an exotic metallic state is generated, exhibiting cuprate-like pseudo-gap spectral properties, for which we propose a surprisingly simple theoretical mechanism.

A calibration method for the measurement of IR detector spectral responses using a FTIR spectrometer equipped with a DTGS reference cell

Science.gov (United States)

Gravrand, Olivier; Wlassow, J.; Bonnefond, L.

2014-07-01

Various high performance IR detectors are today available on the market from QWIPs to narrow gap semiconductor photodiodes, which exhibit various spectral features. In the astrophysics community, the knowledge of the detector spectral shape is of first importance. This quantity (spectral QE or response) is usually measured by means of a monochromator followed by an integrating sphere and compared to a calibrated reference detector. This approach is usually very efficient in the visible range, where all optical elements are very well known, particularly the reference detector. This setup is also widely used in the near IR (up to 3μm) but as the wavelength increases, it becomes less efficient. For instance, the internal emittance of integrating spheres in the IR, and the bad knowledge of reference detectors for longer wavelengths tend to degrade the measurement reliability. Another approach may therefore be considered, using a Fourier transform IR spectrometer (FTIR). In this case, as opposed to the monochromator, the tested detector is not in low flux condition, the incident light containing a mix of different wavelengths. Therefore, the reference detector has to be to be sensitive (and known) in the whole spectral band of interest, because it will sense all those wavelengths at the same time. A popular detector used in this case is a Deuterated Triglycine Sulfate thermal detector (DTGS). Being a pyro detetector, the spectral response of such a detector is very flat, mainly limited by its window. However, the response of such a detector is very slow, highly depending on the temporal frequency of the input signal. Moreover, being a differential detector, it doesn't work in DC. In commercial FTIR spectrometers, the source luminance is usually continuously modulated by the moving interferometer, and the result is that the interferogram mixes optical spectral information (optical path difference) and temporal variations (temporal frequency) so that the temporal

A spectral measurement method for determining white OLED average junction temperatures

Science.gov (United States)

Zhu, Yiting; Narendran, Nadarajah

2016-09-01

The objective of this study was to investigate an indirect method of measuring the average junction temperature of a white organic light-emitting diode (OLED) based on temperature sensitivity differences in the radiant power emitted by individual emitter materials (i.e., "blue," "green," and "red"). The measured spectral power distributions (SPDs) of the white OLED as a function of temperature showed amplitude decrease as a function of temperature in the different spectral bands, red, green, and blue. Analyzed data showed a good linear correlation between the integrated radiance for each spectral band and the OLED panel temperature, measured at a reference point on the back surface of the panel. The integrated radiance ratio of the spectral band green compared to red, (G/R), correlates linearly with panel temperature. Assuming that the panel reference point temperature is proportional to the average junction temperature of the OLED panel, the G/R ratio can be used for estimating the average junction temperature of an OLED panel.

The design and application of a multi-band IR imager

Science.gov (United States)

Li, Lijuan

2018-02-01

Multi-band IR imaging system has many applications in security, national defense, petroleum and gas industry, etc. So the relevant technologies are getting more and more attention in rent years. As we know, when used in missile warning and missile seeker systems, multi-band IR imaging technology has the advantage of high target recognition capability and low false alarm rate if suitable spectral bands are selected. Compared with traditional single band IR imager, multi-band IR imager can make use of spectral features in addition to space and time domain features to discriminate target from background clutters and decoys. So, one of the key work is to select the right spectral bands in which the feature difference between target and false target is evident and is well utilized. Multi-band IR imager is a useful instrument to collect multi-band IR images of target, backgrounds and decoys for spectral band selection study at low cost and with adjustable parameters and property compared with commercial imaging spectrometer. In this paper, a multi-band IR imaging system is developed which is suitable to collect 4 spectral band images of various scenes at every turn and can be expanded to other short-wave and mid-wave IR spectral bands combination by changing filter groups. The multi-band IR imaging system consists of a broad band optical system, a cryogenic InSb large array detector, a spinning filter wheel and electronic processing system. The multi-band IR imaging system's performance is tested in real data collection experiments.

Modeling of SOC-700 Hyperspectral Imagery with the CAMEO-SIM Code

National Research Council Canada - National Science Library

Evans, Roger

2007-01-01

The CAMEO-SIM software program provides a physics-based spectral radiance simulation over the complete range from UV to Far-IR, the only real limitation being one of obtaining the necessary input data...

The effects of downwelling radiance on MER surface spectra: the evil that atmospheres do

Science.gov (United States)

Wolff, M.; Ghosh, A.; Arvidson, R.; Christensen, P.; Guinness, E.; Ruff, S.; Seelos, F.; Smith, M.; Athena Science

2004-11-01

While it may not be surprising to some that downwelling radiation in the martian atmosphere may contribute a non-negligible fraction of the radiance for a given surface scene, others remain shocked and surprised (and often dismayed) to discover this fact; particularly with regard to mini-TES observations. Naturally, the relative amplitude of this sky ``contamination'' is often a complicated function of meteorological conditions, viewing geometry, surface properties, and (for the IR) surface temperature. Ideally, one would use a specialized observations to mimic the actual hemispherical-directional nature of the problem. Despite repeated attempts to obtain Pancam complete sky observations and mini-TES sky octants, such observations are not available in the MER observational database. As a result, one is left with the less-enviable, though certainly more computationally intensive, task of connecting point observations (radiance and derived meteorological parameters) to a hemispherical integral of downwelling radiance. Naturally, one must turn to a radiative transfer analysis, despite oft-repeated attempts to assert otherwise. In our presentation, we offer insight into the conditions under which one must worry about atmospheric removal, as well as semi-empirical approaches (based upon said radiative transfer efforts) for producing the correction factors from the available MER atmospheric observations. This work is proudly supported by the MER program through NASA/JPL Contract No. 1242889 (MJW), as well as the contracts for the co-authors.

Normal spectral emissivity measurement of molten copper using an electromagnetic levitator superimposed with a static magnetic field

International Nuclear Information System (INIS)

Kurosawa, Ryo; Inoue, Takamitsu; Baba, Yuya; Sugioka, Ken-ichi; Kubo, Masaki; Tsukada, Takao; Fukuyama, Hiroyuki

2013-01-01

The normal spectral emissivity of molten copper was determined in the wavelength range of 780–920 nm and in the temperature range of 1288–1678 K, by directly measuring the radiance emitted by an electromagnetically levitated molten copper droplet under a static magnetic field of 1.5 T. The spectrometer for radiance measurement was calibrated using the relation between the theoretical blackbody radiance from Planck's law and the light intensity of a quasi-blackbody radiation source measured using a spectrometer at a given temperature. As a result, the normal spectral emissivity of molten copper was determined as 0.075 ± 0.011 at a wavelength of 807 nm, and it was found that its temperature dependence is negligible in the entire measurement temperature range tested. In addition, the results of the normal spectral emissivity and its wavelength dependence were discussed, in comparison with those obtained using the Drude free-electron model. (paper)

Quantitative impact of aerosols on numerical weather prediction. Part II: Impacts to IR radiance assimilation

Science.gov (United States)

Marquis, J. W.; Campbell, J. R.; Oyola, M. I.; Ruston, B. C.; Zhang, J.

2017-12-01

This is part II of a two-part series examining the impacts of aerosol particles on weather forecasts. In this study, the aerosol indirect effects on weather forecasts are explored by examining the temperature and moisture analysis associated with assimilating dust contaminated hyperspectral infrared radiances. The dust induced temperature and moisture biases are quantified for different aerosol vertical distribution and loading scenarios. The overall impacts of dust contamination on temperature and moisture forecasts are quantified over the west coast of Africa, with the assistance of aerosol retrievals from AERONET, MPL, and CALIOP. At last, methods for improving hyperspectral infrared data assimilation in dust contaminated regions are proposed.

One year of downwelling spectral radiance measurements from 100 to 1400 cm-1 at Dome Concordia: Results in clear conditions

Science.gov (United States)

Rizzi, R.; Arosio, C.; Maestri, T.; Palchetti, L.; Bianchini, G.; Del Guasta, M.

2016-09-01

The present work examines downwelling radiance spectra measured at the ground during 2013 by a Far Infrared Fourier Transform Spectrometer at Dome C, Antarctica. A tropospheric backscatter and depolarization lidar is also deployed at same site, and a radiosonde system is routinely operative. The measurements allow characterization of the water vapor and clouds infrared properties in Antarctica under all sky conditions. In this paper we specifically discuss cloud detection and the analysis in clear sky condition, required for the discussion of the results obtained in cloudy conditions. First, the paper discusses the procedures adopted for the quality control of spectra acquired automatically. Then it describes the classification procedure used to discriminate spectra measured in clear sky from cloudy conditions. Finally a selection is performed and 66 clear cases, spanning the whole year, are compared to simulations. The computation of layer molecular optical depth is performed with line-by-line techniques and a convolution to simulate the Radiation Explorer in the Far InfraRed-Prototype for Applications and Development (REFIR-PAD) measurements; the downwelling radiance for selected clear cases is computed with a state-of-the-art adding-doubling code. The mean difference over all selected cases between simulated and measured radiance is within experimental error for all the selected microwindows except for the negative residuals found for all microwindows in the range 200 to 400 cm-1, with largest values around 295.1 cm-1. The paper discusses possible reasons for the discrepancy and identifies the incorrect magnitude of the water vapor total absorption coefficient as the cause of such large negative radiance bias below 400 cm-1.

A Web Service Tool (SOAR) for the Dynamic Generation of L1 Grids of Coincident AIRS, AMSU and MODIS Satellite Sounding Radiance Data for Climate Studies

Science.gov (United States)

Halem, M.; Yesha, Y.; Tilmes, C.; Chapman, D.; Goldberg, M.; Zhou, L.

2007-05-01

Three decades of Earth remote sensing from NASA, NOAA and DOD operational and research satellites carrying successive generations of improved atmospheric sounder instruments have resulted in petabytes of radiance data with varying spatial and spectral resolutions being stored at different data archives in various data formats by the respective agencies. This evolution of sounders and the diversities of these archived data sets have led to data processing obstacles limiting the science community from readily accessing and analyzing such long-term climate data records. We address this problem by the development of a web based Service Oriented Atmospheric Radiance (SOAR) system built on the SOA paradigm that makes it practical for the science community to dynamically access, manipulate and generate long term records of L1 pre-gridded sounding radiances of coincident multi-sensor data for regions specified according to user chosen criteria. SOAR employs a modification of the standard Client Server interactions that allows users to represent themselves directly to the Process Server through their own web browsers. The browser uses AJAX to request Javascript libraries and DHTML interfaces that define the possible client interactions and communicates the SOAP messages to the Process server allowing for dynamic web dialogs with the user to take place on the fly. The Process Server is also connected to an underlying high performance compute cluster and storage system which provides much of the data processing capabilities required to service the client requests. The compute cluster employs optical communications to NOAA and NASA for accessing the data and under the governance of the Process Server invokes algorithms for on-demand spatial, temporal, and spectral gridding. Scientists can choose from a variety of statistical averaging techniques for compositing satellite observed sounder radiances from the AIRS, AMSU or MODIS instruments to form spatial-temporal grids for

Performance of spectral fitting methods for vegetation fluorescence quantification

NARCIS (Netherlands)

Meroni, M.; Busetto, D.; Colombo, R.; Guanter, L.; Moreno, J.; Verhoef, W.

2010-01-01

The Fraunhofer Line Discriminator (FLD) principle has long been considered as the reference method to quantify solar-induced chlorophyll fluorescence (F) from passive remote sensing measurements. Recently, alternative retrieval algorithms based on the spectral fitting of hyperspectral radiance

Generalized radiative transfer theory for scattering by particles in an absorbing gas: Addressing both spatial and spectral integration in multi-angle remote sensing of optically thin aerosol layers

Science.gov (United States)

Davis, Anthony B.; Xu, Feng; Diner, David J.

2018-01-01

We demonstrate the computational advantage gained by introducing non-exponential transmission laws into radiative transfer theory for two specific situations. One is the problem of spatial integration over a large domain where the scattering particles cluster randomly in a medium uniformly filled with an absorbing gas, and only a probabilistic description of the variability is available. The increasingly important application here is passive atmospheric profiling using oxygen absorption in the visible/near-IR spectrum. The other scenario is spectral integration over a region where the absorption cross-section of a spatially uniform gas varies rapidly and widely and, moreover, there are scattering particles embedded in the gas that are distributed uniformly, or not. This comes up in many applications, O2 A-band profiling being just one instance. We bring a common framework to solve these problems both efficiently and accurately that is grounded in the recently developed theory of Generalized Radiative Transfer (GRT). In GRT, the classic exponential law of transmission is replaced by one with a slower power-law decay that accounts for the unresolved spectral or spatial variability. Analytical results are derived in the single-scattering limit that applies to optically thin aerosol layers. In spectral integration, a modest gain in accuracy is obtained. As for spatial integration of near-monochromatic radiance, we find that, although both continuum and in-band radiances are affected by moderate levels of sub-pixel variability, only extreme variability will affect in-band/continuum ratios.

UNTANGLING THE NEAR-IR SPECTRAL FEATURES IN THE PROTOPLANETARY ENVIRONMENT OF KH 15D

Energy Technology Data Exchange (ETDEWEB)

Arulanantham, Nicole A.; Herbst, William; Gilmore, Martha S.; Cauley, P. Wilson [Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States); Leggett, S. K., E-mail: nicole.arulanantham@colorado.edu [Gemini Observatory (North), Hilo, HI 96720 (United States)

2017-01-10

We report on Gemini/GNIRS observations of the binary T Tauri system V582 Mon (KH 15D) at three orbital phases. These spectra allow us to untangle five components of the system: the photosphere and magnetosphere of star B, the jet, scattering properties of the ring material, and excess near-infrared (near-IR) radiation previously attributed to a possible self-luminous planet. We confirm an early-K subgiant classification for star B and show that the magnetospheric He i emission line is variable, possibly indicating increased mass accretion at certain times. As expected, the H{sub 2} emission features associated with the inner part of the jet show no variation with orbital phase. We show that the reflectance spectrum for the scattered light has a distinctive blue slope and spectral features consistent with scattering and absorption by a mixture of water and methane ice grains in the 1–50 μ m size range. This suggests that the methane frost line is closer than ∼5 au in this system, requiring that the grains be shielded from direct radiation. After correcting for features from the scattered light, jet, magnetosphere, and photosphere, we confirm the presence of leftover near-IR light from an additional source, detectable near minimum brightness. A spectral emission feature matching the model spectrum of a 10 M {sub J}, 1 Myr old planet is found in the excess flux, but other expected features from this model are not seen. Our observations, therefore, tentatively support the picture that a luminous planet is present within the system, although they cannot yet be considered definitive.

Emissivity compensated spectral pyrometry—algorithm and sensitivity analysis

International Nuclear Information System (INIS)

Hagqvist, Petter; Sikström, Fredrik; Christiansson, Anna-Karin; Lennartson, Bengt

2014-01-01

In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and evaluated. The method uses spectral radiance measurements and converts them to temperature readings. It proves to be resilient towards changes in spectral emissivity and tolerates noisy spectral measurements. It is based on an assumption of smooth changes in emissivity and uses historical values of spectral emissivity and temperature for estimating current spectral emissivity. The algorithm, its constituent steps and accompanying parameters are described and discussed. A thorough sensitivity analysis of the method is carried out through simulations. No rigorous instrument calibration is needed for the presented method and it is therefore industrially tractable. (paper)

An overview of surface radiance and biology studies in FIFE

Science.gov (United States)

Blad, B. L.; Schimel, D. S.

1992-01-01

The use of satellite data to study and to understand energy and mass exchanges between the land surface and the atmosphere requires information about various biological processes and how various reflected or emitted spectral radiances are influenced by or manifested in these processes. To obtain such information, studies were conducted by the First ISLSCP Field Experiment (FIFE) surface radiances and biology (SRB) group using surface, near-surface, helicopter, and aircraft measurements. The two primary objectives of this group were to relate radiative fluxes to biophysical parameters and physiological processes and to assess how various management treatments affect important biological processes. This overview paper summarizes the results obtained by various SRB teams working in nine different areas: (1) measurements of bidirectional reflectance and estimation of hemispherical albedo; (2) evaluation of spatial and seasonal variability reflectance and vegetation indices; (3) determination of surface and radiational factors and their effects on vegetation indices and photosynthetically active radiation relationships; (4) use of surface temperatures to estimate sensible heat flux; (5) controls over photosynthesis and respiration at small scales; (6) soil surface CO2 fluxes and grassland carbon budget; (7) landscape variations in controls over gas exchange and energy partitioning; (8) radiometric response of prairie to management and topography; and (9) determination of nitrogen gas exchanges in a tallgrass prairie.

Interstitial diffuse radiance spectroscopy of gold nanocages and nanorods in bulk muscle tissues.

Science.gov (United States)

Grabtchak, Serge; Montgomery, Logan G; Pang, Bo; Wang, Yi; Zhang, Chao; Li, Zhiyuan; Xia, Younan; Whelan, William M

2015-01-01

Radiance spectroscopy was applied to the interstitial detection of localized inclusions containing Au nanocages or nanorods with various concentrations embedded in porcine muscle phantoms. The radiance was quantified using a perturbation approach, which enabled the separation of contributions from the porcine phantom and the localized inclusion, with the inclusion serving as a perturbation probe of photon distributions in the turbid medium. Positioning the inclusion at various places in the phantom allowed for tracking of photons that originated from a light source, passed through the inclusion's location, and reached a detector. The inclusions with high extinction coefficients were able to absorb nearly all photons in the range of 650-900 nm, leading to a spectrally flat radiance signal. This signal could be converted to the relative density of photons incident on the inclusion. Finally, the experimentally measured quantities were expressed via the relative perturbation and arranged into the classical Beer-Lambert law that allowed one to extract the extinction coefficients of various types of Au nanoparticles in both the transmission and back reflection geometries. It was shown that the spatial variation of perturbation could be described as 1/r dependence, where r is the distance between the inclusion and the detector. Due to a larger absorption cross section, Au nanocages produced greater perturbations than Au nanorods of equal particle concentration, indicating a better suitability of Au nanocages as contrast agents for optical measurements in turbid media. Individual measurements from different inclusions were combined into detectability maps.

Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region

Science.gov (United States)

Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping

2016-01-01

A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.

Study on IR Properties of Reduced Graphene Oxide

Science.gov (United States)

Ma, Deyue; Li, Xiaoxia; Guo, Yuxiang; Zeng, Yurun

2018-01-01

Firstly, the reduced graphene oxide was prepared by modified hummer method and characterized. Then, the complex refractive index of reduced graphene oxide in IR band was tested and its IR absorption and radiation properties were researched by correlated calculation. The results show that reduced graphene oxide prepared by hummer method are multilayered graphene with defects and functional groups on its surface. Its absorption in near and far IR bands is strong, but it’s weaker in middle IR band. At the IR atmosphere Window, its normal spectral emissivity decreases with wavelength increasing, and its total normal spectral emissivity in 3 ∼ 5μm and 8 ∼ 14μm are 0.75 and 0.625, respectively. Therefore, reduced graphene oxide can be used as IR absorption and coating materials and have a great potential in microwave and infrared compatible materials.

Glue Film Thickness Measurements by Spectral Reflectance

International Nuclear Information System (INIS)

Marshall, B.R.

2010-01-01

Spectral reflectance was used to determine the thickness of thin glue layers in a study of the effect of the glue on radiance and reflectance measurements of shocked-tin substrates attached to lithium fluoride windows. Measurements based on profilometry of the components were found to be inaccurate due to flatness variations and deformation of the tin substrate under pressure during the gluing process. The accuracy of the spectral reflectance measurements were estimated to be ±0.5 (micro)m, which was sufficient to demonstrate a convincing correlation between glue thickness and shock-generated light.

Glue Film Thickness Measurements by Spectral Reflectance

Energy Technology Data Exchange (ETDEWEB)

B. R. Marshall

2010-09-20

Spectral reflectance was used to determine the thickness of thin glue layers in a study of the effect of the glue on radiance and reflectance measurements of shocked-tin substrates attached to lithium fluoride windows. Measurements based on profilometry of the components were found to be inaccurate due to flatness variations and deformation of the tin substrate under pressure during the gluing process. The accuracy of the spectral reflectance measurements were estimated to be ±0.5 μm, which was sufficient to demonstrate a convincing correlation between glue thickness and shock-generated light.

Super-radiance in Nuclear Physics

International Nuclear Information System (INIS)

Auerbach, N

2015-01-01

The theory of the super-radiant mechanism as applied to various phenomena in nuclear physics is presented. The connection between super-radiance and the notion of doorway is presented. The statistics of resonance widths in a many-body Fermi system with open channels is discussed. Depending on the strength of the coupling to the continuum such systems show deviations from the standard Porter-Thomas distribution. The deviations result from the process of increasing interaction of the intrinsic states via the common decay channels. In the limit of very strong coupling this leads to super-radiance. (paper)

Disk and circumsolar radiances in the presence of ice clouds

Directory of Open Access Journals (Sweden)

P. Haapanala

2017-06-01

Full Text Available The impact of ice clouds on solar disk and circumsolar radiances is investigated using a Monte Carlo radiative transfer model. The monochromatic direct and diffuse radiances are simulated at angles of 0 to 8° from the center of the sun. Input data for the model are derived from measurements conducted during the 2010 Small Particles in Cirrus (SPARTICUS campaign together with state-of-the-art databases of optical properties of ice crystals and aerosols. For selected cases, the simulated radiances are compared with ground-based radiance measurements obtained by the Sun and Aureole Measurements (SAM instrument. First, the sensitivity of the radiances to the ice cloud properties and aerosol optical thickness is addressed. The angular dependence of the disk and circumsolar radiances is found to be most sensitive to assumptions about ice crystal roughness (or, more generally, non-ideal features of ice crystals and size distribution, with ice crystal habit playing a somewhat smaller role. Second, in comparisons with SAM data, the ice cloud optical thickness is adjusted for each case so that the simulated radiances agree closely (i.e., within 3 % with the measured disk radiances. Circumsolar radiances at angles larger than ≈ 3° are systematically underestimated when assuming smooth ice crystals, whereas the agreement with the measurements is better when rough ice crystals are assumed. Our results suggest that it may well be possible to infer the particle roughness directly from ground-based SAM measurements. In addition, the results show the necessity of correcting the ground-based measurements of direct radiation for the presence of diffuse radiation in the instrument's field of view, in particular in the presence of ice clouds.

Measured Polarized Spectral Responsivity of JPSS J1 VIIRS Using the NIST T-SIRCUS

Science.gov (United States)

McIntire, Jeff; Young, James B.; Moyer, David; Waluschka, Eugene; Xiong, Xiaoxiong

2015-01-01

Recent pre-launch measurements performed on the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) using the National Institute of Standards and Technology (NIST) Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources (T-SIRCUS) monochromatic source have provided wavelength dependent polarization sensitivity for select spectral bands and viewing conditions. Measurements were made at a number of input linear polarization states (twelve in total) and initially at thirteen wavelengths across the bandpass (later expanded to seventeen for some cases). Using the source radiance information collected by an external monitor, a spectral responsivity function was constructed for each input linear polarization state. Additionally, an unpolarized spectral responsivity function was derived from these polarized measurements. An investigation of how the centroid, bandwidth, and detector responsivity vary with polarization state was weighted by two model input spectra to simulate both ground measurements as well as expected on-orbit conditions. These measurements will enhance our understanding of VIIRS polarization sensitivity, improve the design for future flight models, and provide valuable data to enhance product quality in the post-launch phase.

RADIANCE DOMAIN COMPOSITING FOR HIGH DYNAMIC RANGE IMAGING

Directory of Open Access Journals (Sweden)

M.R. Renu

2013-02-01

Full Text Available High dynamic range imaging aims at creating an image with a range of intensity variations larger than the range supported by a camera sensor. Most commonly used methods combine multiple exposure low dynamic range (LDR images, to obtain the high dynamic range (HDR image. Available methods typically neglect the noise term while finding appropriate weighting functions to estimate the camera response function as well as the radiance map. We look at the HDR imaging problem in a denoising frame work and aim at reconstructing a low noise radiance map from noisy low dynamic range images, which is tone mapped to get the LDR equivalent of the HDR image. We propose a maximum aposteriori probability (MAP based reconstruction of the HDR image using Gibb’s prior to model the radiance map, with total variation (TV as the prior to avoid unnecessary smoothing of the radiance field. To make the computation with TV prior efficient, we extend the majorize-minimize method of upper bounding the total variation by a quadratic function to our case which has a nonlinear term arising from the camera response function. A theoretical justification for doing radiance domain denoising as opposed to image domain denoising is also provided.

Modeling Top of Atmosphere Radiance over Heterogeneous Non-Lambertian Rugged Terrain

Directory of Open Access Journals (Sweden)

Alijafar Mousivand

2015-06-01

Full Text Available Topography affects the fraction of direct and diffuse radiation received on a pixel and changes the sun–target–sensor geometry, resulting in variations in the observed radiance. Retrieval of surface–atmosphere properties from top of atmosphere radiance may need to account for topographic effects. This study investigates how such effects can be taken into account for top of atmosphere radiance modeling. In this paper, a system for top of atmosphere radiance modeling over heterogeneous non-Lambertian rugged terrain through radiative transfer modeling is presented. The paper proposes an extension of “the four-stream radiative transfer theory” (Verhoef and Bach 2003, 2007 and 2012 mainly aimed at representing topography-induced contributions to the top of atmosphere radiance modeling. A detailed account for BRDF effects, adjacency effects and topography effects on the radiance modeling is given, in which sky-view factor and non-Lambertian reflected radiance from adjacent slopes are modeled precisely. The paper also provides a new formulation to derive the atmospheric coefficients from MODTRAN with only two model runs, to make it more computationally efficient and also avoiding the use of zero surface albedo as used in the four-stream radiative transfer theory. The modeling begins with four surface reflectance factors calculated by the Soil–Leaf–Canopy radiative transfer model SLC at the top of canopy and propagates them through the effects of the atmosphere, which is explained by six atmospheric coefficients, derived from MODTRAN radiative transfer code. The top of the atmosphere radiance is then convolved with the sensor characteristics to generate sensor-like radiance. Using a composite dataset, it has been shown that neglecting sky view factor and/or terrain reflected radiance can cause uncertainty in the forward TOA radiance modeling up to 5 (mW/m2·sr·nm. It has also been shown that this level of uncertainty can be translated

All-sky radiance simulation of Megha-Tropiques SAPHIR microwave ...

Indian Academy of Sciences (India)

used as input to the RTTOV model to simulate cloud-affected SAPHIR radiances. ... All-sky radiance simulation; Megha tropiques; microwave SAPHIR sensor; radiative transfer; data ... versions of these non-linear processes (Ohring and.

An unbiased spectral line survey toward R CrA IRS7B in the 345 GHz window with ASTE

DEFF Research Database (Denmark)

Watanabe, Yoshimasa; Sakai, Nami; Lindberg, Johan

2012-01-01

We have conducted a spectral line survey in the 332-364 GHz region with the Atacama Submillimeter Telescope Experiment 10 m telescope toward R CrA IRS7B, a low-mass protostar in the Class 0 or Class 0/I transitional stage. We have also performed some supplementary observations in the 450 GHz band...... corino. These results suggest a weak hot corino activity in R CrA IRS7B. On the other hand, the carbon-chain related molecules, CCH and c-C3H2, are found to be abundant. However, this source cannot be classified as a WCCC source, since long carbon-chain molecules are not detected. If WCCC and hot corino...... chemistry represent the two extremes in chemical compositions of low-mass Class 0 sources, R CrA IRS7B would be a source with a mixture of these two chemical characteristics. The UV radiation from the nearby Herbig Ae star R CrA may also affect the chemical composition. The present line survey demonstrates...

Plane parallel radiance transport for global illumination in vegetation

Energy Technology Data Exchange (ETDEWEB)

Max, N.; Mobley, C.; Keating, B.; Wu, E.H.

1997-01-05

This paper applies plane parallel radiance transport techniques to scattering from vegetation. The leaves, stems, and branches are represented as a volume density of scattering surfaces, depending only on height and the vertical component of the surface normal. Ordinary differential equations are written for the multiply scattered radiance as a function of the height above the ground, with the sky radiance and ground reflectance as boundary conditions. They are solved using a two-pass integration scheme to unify the two-point boundary conditions, and Fourier series for the dependence on the azimuthal angle. The resulting radiance distribution is used to precompute diffuse and specular `ambient` shading tables, as a function of height and surface normal, to be used in rendering, together with a z-buffer shadow algorithm for direct solar illumination.

Preliminary Inter-Comparison between AHI, VIIRS and MODIS Clear-Sky Ocean Radiances for Accurate SST Retrievals

Directory of Open Access Journals (Sweden)

Xingming Liang

2016-03-01

Full Text Available Clear-sky brightness temperatures (BT in five bands of the Advanced Himawari Imager (AHI; flown onboard Himawari-8 satellite centered at 3.9, 8.6, 10.4, 11.2, and 12.3 µm (denoted by IR37, IR86, IR10, IR11, and IR12, respectively are used in the NOAA Advanced Clear-Sky Processor for Oceans (ACSPO sea surface temperature (SST retrieval system. Here, AHI BTs are preliminarily evaluated for stability and consistency with the corresponding VIIRS and MODIS BTs, using the sensor observation minus model simulation (O-M biases and corresponding double differences. The objective is to ensure accurate and consistent SST products from the polar and geo sensors, and to prepare for the launch of the GOES-R satellite in 2016. All five AHI SST bands are found to be largely in-family with their polar counterparts, but biased low relative to the VIIRS and MODIS (which, in turn, were found to be stable and consistent, except for Terra IR86, which is biased high by 1.5 K. The negative biases are larger in IR37 and IR12 (up to ~−0.5 K, followed by the three remaining longwave IR bands IR86, IR10, and IR11 (from −0.3 to −0.4 K. These negative biases may be in part due to the uncertainties in AHI calibration and characterization, although uncertainties in the coefficients of the Community Radiative Transfer Model (CRTM, used to generate the “M” term may also contribute. Work is underway to add AHI analyses in the NOAA Monitoring of IR Clear-Sky Radiances over Oceans for SST (MICROS system and improve AHI BTs by collaborating with the sensor calibration and CRTM teams. The Advanced Baseline Imager (ABI analyses will be also added in MICROS when GOES-R is launched in late 2016 and the ABI IR data become available.

Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases

Directory of Open Access Journals (Sweden)

N. C. Atkinson

2010-07-01

Full Text Available Principal component (PC analysis has received considerable attention as a technique for the extraction of meteorological signals from hyperspectral infra-red sounders such as the Infrared Atmospheric Sounding Interferometer (IASI and the Atmospheric Infrared Sounder (AIRS. In addition to achieving substantial bit-volume reductions for dissemination purposes, the technique can also be used to generate reconstructed radiances in which random instrument noise has been reduced. Studies on PC analysis of hyperspectral infrared sounder data have been undertaken in the context of numerical weather prediction, instrument monitoring and geophysical variable retrieval, as well as data compression. This study examines the potential of PC analysis for chemistry applications.

A major concern in the use of PC analysis for chemistry is that the spectral features associated with trace gases may not be well represented in the reconstructed spectra, either due to deficiencies in the training set or due to the limited number of PC scores used in the radiance reconstruction. In this paper we show examples of reconstructed IASI radiances for several trace gases: ammonia, sulphur dioxide, methane and carbon monoxide. It is shown that care must be taken in the selection of spectra for the initial training set: an iterative technique, in which outlier spectra are added to a base training set, gives the best results. For the four trace gases examined, key features of the chemical signatures are retained in the reconstructed radiances, whilst achieving a substantial reduction in instrument noise.

A new regional re-transmission service for IASI is scheduled to start in 2010, as part of the EUMETSAT Advanced Retransmission Service (EARS. For this EARS-IASI service it is intended to include PC scores as part of the data stream. The paper describes the generation of the reference eigenvectors for this new service.

Quantitative gas analysis with FT-IR

DEFF Research Database (Denmark)

Bak, J.; Larsen, A.

1995-01-01

Calibration spectra of CO in the 2.38-5100 ppm concentration range (22 spectra) have been measured with a spectral resolution of 4 cm(-1), in the mid-IR (2186-2001 cm(-1)) region, with a Fourier transform infrared (FT-IR) instrument. The multivariate calibration method partial least-squares (PLS1...

Composite multi-lobe descriptor for cross spectral face recognition: matching active IR to visible light images

Science.gov (United States)

Cao, Zhicheng; Schmid, Natalia A.

2015-05-01

Matching facial images across electromagnetic spectrum presents a challenging problem in the field of biometrics and identity management. An example of this problem includes cross spectral matching of active infrared (IR) face images or thermal IR face images against a dataset of visible light images. This paper describes a new operator named Composite Multi-Lobe Descriptor (CMLD) for facial feature extraction in cross spectral matching of near-infrared (NIR) or short-wave infrared (SWIR) against visible light images. The new operator is inspired by the design of ordinal measures. The operator combines Gaussian-based multi-lobe kernel functions, Local Binary Pattern (LBP), generalized LBP (GLBP) and Weber Local Descriptor (WLD) and modifies them into multi-lobe functions with smoothed neighborhoods. The new operator encodes both the magnitude and phase responses of Gabor filters. The combining of LBP and WLD utilizes both the orientation and intensity information of edges. Introduction of multi-lobe functions with smoothed neighborhoods further makes the proposed operator robust against noise and poor image quality. Output templates are transformed into histograms and then compared by means of a symmetric Kullback-Leibler metric resulting in a matching score. The performance of the multi-lobe descriptor is compared with that of other operators such as LBP, Histogram of Oriented Gradients (HOG), ordinal measures, and their combinations. The experimental results show that in many cases the proposed method, CMLD, outperforms the other operators and their combinations. In addition to different infrared spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated in this paper. Performance of CMLD is evaluated for of each of the three cases of distances.

New stratospheric UV/visible radiance measurements

Directory of Open Access Journals (Sweden)

F. J. Marceau

1994-01-01

Full Text Available A stratospheric balloon was launched on 12 October 1986 from the "CNES" base at Aire sur l'Adour (France to record twilight radiance in the stratosphere. The near-UV and visible radiances were continuously monitored by a photometer during sunrise. Some observations are presented for different viewing azimuthal planes and viewing elevation angles. They show the influence of aerosols layers and clouds which can be also seen on related photographs. The results as a whole may be used for testing some radiative models, especially for twilight conditions.

Radiance limits of ceramic phosphors under high excitation fluxes

Science.gov (United States)

Lenef, Alan; Kelso, John; Zheng, Yi; Tchoul, Maxim

2013-09-01

Ceramic phosphors, excited by high radiance pump sources, offer considerable potential for high radiance conversion. Interestingly, thermodynamic arguments suggest that the radiance of the luminescent spot can even exceed that of the incoming light source. In practice, however, thermal quenching and (non-thermal) optical saturation limit the maximum attainable radiance of the luminescent source. We present experimental data for Ce:YAG and Ce:GdYAG ceramics in which these limits have been investigated. High excitation fluxes are achieved using laser pumping. Optical pumping intensities exceeding 100W/mm2 have been shown to produce only modest efficiency depreciation at low overall pump powers because of the short Ce3+ lifetime, although additional limitations exist. When pump powers are higher, heat-transfer bottlenecks within the ceramic and heat-sink interfaces limit maximum pump intensities. We find that surface temperatures of these laser-pumped ceramics can reach well over 150°C, causing thermal-quenching losses. We also find that in some cases, the loss of quantum efficiency with increasing temperature can cause a thermal run-away effect, resulting in a rapid loss in converted light, possibly over-heating the sample or surrounding structures. While one can still obtain radiances on the order of many W/mm2/sr, temperature quenching effects ultimately limit converted light radiance. Finally, we use the diffusion-approximation radiation transport models and rate equation models to simulate some of these nonlinear optical pumping and heating effects in high-scattering ceramics.

THE ORION FINGERS: NEAR-IR SPECTRAL IMAGING OF AN EXPLOSIVE OUTFLOW

Energy Technology Data Exchange (ETDEWEB)

Youngblood, Allison; Bally, John [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Ginsburg, Adam, E-mail: allison.youngblood@colorado.edu [ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)

2016-06-01

We present near-IR (1.1–2.4 μ m) position–position–velocity cubes of the 500 year old Orion BN/KL explosive outflow with spatial resolution 1″ and spectral resolution 86 km s{sup −1}. We construct integrated intensity maps free of continuum sources of 15 H{sub 2} and [Fe ii] lines while preserving kinematic information of individual outflow features. Included in the detected H{sub 2} lines are the 1-0 S(1) and 1-0 Q(3) transitions, allowing extinction measurements across the outflow. Additionally, we present dereddened flux ratios for over two dozen outflow features to allow for the characterization of the true excitation conditions of the BN/KL outflow. All of the ratios show the dominance of the shock excitation of the H{sub 2} emission, although some features exhibit signs of fluorescent excitation from stellar radiation or J-type shocks. We also detect tracers of the PDR/ionization front north of the Trapezium stars in [O i] and [Fe ii] and analyze other observed outflows not associated with the BN/KL outflow.

Primary Radiometry for the mise-en-pratique: The Laser-Based Radiance Method Applied to a Pyrometer

Science.gov (United States)

Briaudeau, S.; Sadli, M.; Bourson, F.; Rougi, B.; Rihan, A.; Zondy, J.-J.

2011-12-01

A new setup has been implemented at LCM-LNE-CNAM for the determination "of the spectral responsivity of radiation thermometers for the determination" of the thermodynamic temperature of high-temperature blackbodies at the temperature of a metal-carbon eutectic phase transition. In this new setup, an innovative acoustic-optic modulator feedback loop is used to stabilize the radiance of a wavelength tunable laser. The effect of residual optical interferences on the calibration of a test pyrometer is analyzed. The full uncertainty budget is presented.

Accuracy in mineral identification: image spectral and spatial resolutions and mineral spectral properties

Directory of Open Access Journals (Sweden)

L. Pompilio

2006-06-01

Full Text Available Problems related to airborne hyperspectral image data are reviewed and the requirements for data analysis applied to mineralogical (rocks and soils interpretation are discussed. The variability of mineral spectral features, including absorption position, shape and depth is considered and interpreted as due to chemical composition, grain size effects and mineral association. It is also shown how this variability can be related to well defined geologic processes. The influence of sensor noise and diffuse atmospheric radiance in classification accuracy is also analyzed.

A climate index derived from satellite measured spectral infrared radiation. Ph.D. Thesis

Science.gov (United States)

Abel, M. D.; Fox, S. K.

1982-01-01

The vertical infrared radiative emitting structure (VIRES) climate index, based on radiative transfer theory and derived from the spectral radiances typically used to retrieve temperature profiles, is introduced. It is assumed that clouds and climate are closely related and a change in one will result in a change in the other. The index is a function of the cloud, temperature, and moisture distributions. It is more accurately retrieved from satellite data than is cloudiness per se. The VIRES index is based upon the shape and relative magnitude of the broadband weighting function of the infrared radiative transfer equation. The broadband weighting curves are retrieved from simulated satellite infrared sounder data (spectral radiances). The retrieval procedure is described and the error error sensitivities of the method investigated. Index measuring options and possible applications of the VIRES index are proposed.

Retrieved Products from Simulated Hyperspectral Observations of a Hurricane

Science.gov (United States)

Susskind, Joel; Kouvaris, Louis; Iredell, Lena; Blaisdell, John

2015-01-01

Demonstrate via Observing System Simulation Experiments (OSSEs) the potential utility of flying high spatial resolution AIRS class IR sounders on future LEO and GEO missions.The study simulates and analyzes radiances for 3 sounders with AIRS spectral and radiometric properties on different orbits with different spatial resolutions: 1) Control run 13 kilometers AIRS spatial resolution at nadir on LEO in Aqua orbit; 2) 2 kilometer spatial resolution LEO sounder at nadir ARIES; 3) 5 kilometers spatial resolution sounder on a GEO orbit, radiances simulated every 72 minutes.

The DMSP/MFR total ozone and radiance data base

International Nuclear Information System (INIS)

Ellis, J.S.; Lovill, J.E.; Luther, F.M.; Sullivan, T.J.; Taylor, S.S.; Weichel, R.L.

1992-01-01

The radiance measurements by the multichannel filter radiometer (MFR), a scanning instrument carried on the Defense Meteorological Satellite Program (DMSP) Block 5D series of satellites (flight models F1, F2, F3 and F4), were used to calculate the total column ozone globally for the period March 1977 through February 1980. These data were then calibrated and mapped to earth coordinates at LLNL. Total column ozone was derived from these calibrated radiance data and placed both the ozone and calibrated radiance data into a computer data base called SOAC (Satellite Ozone Analysis Center) using the FRAMIS database manager. The uncalibrated radiance data tapes were initially sent on to the National Climate Center, Asheville, North Carolina and then to the Satellite Data Services Branch /EDS/NOAA in Suitland, Maryland where they were archived. Copies of the data base containing the total ozone and the calibrated radiance data reside both at LLNL and at the National Space Science Data Center, NASA Goddard Space Flight Center, Greenbelt, Maryland. This report describes the entries into the data base in sufficient detail so that the data base might be useful to others. The characteristics of the MFR sensor are briefly discussed and a complete index to the data base tapes is given

Cloud Computing Infusion for Generating ESDRs of Visible Spectra Radiances

Science.gov (United States)

Golpayegani, N.; Halem, M.; Nguyen, P.

2008-12-01

The AIRS and AVHRR instruments have been collecting radiances of the Earth in the visible spectrum for over 25 years. These measurements have been used to develop such useful products as NDVI, Snow cover and depth, Outgoing long wave radiation and other products. Yet, no long-term data record of the level 1b visible spectra is available in a grid form to researchers for various climate studies. We present here an Earth System Data Record observed in the visible spectrum as gridded radiance fields of 8kmx10km grid resolution for the six years in the case of AIRS and from 1981 to the present for AVHRR. The AIRS data has four visible channels from 0.41μm to 0.94μm with an IFOV of 1 km and AVHRR has two visible channels in the 0.58μm to 1.00μm range also at 1 km. In order to process such large amounts of data on demand, two components need to be implemented,(i) a processing system capable of gridding TBs of data in a reasonable amount of time and (ii) a download mechanism to access and deliver the data to the processing system. We implemented a cloud computing approach to be able to process such large amounts of data. We use Hadoop, a distributed computation system developed by the Apache Software Foundation. With Hadoop, we are able to store the data in a distributed fashion, taking advantage of Hadoop's distributed file system (dfs). We also take advantage of Hadoop's MapReduce functionality to perform as much computations as is possible on available nodes of the UMBC bluegrit Cell cluster system that contain the data. We make use of the SOAR system developed under the ACCESS program to acquire and process the AIRS and AVHRR observations. Comparisons of the AIRS data witth selected periods of MODIS visible spectral channels on the same sattelite indicate the two instruments have maintained calibration consistency and continuity of their measurements over the six year period. Our download mechanism transfers the data from these instruments into hadoop's dfs. Our

Upconversion applied for mid-IR hyperspectral image acquisition

DEFF Research Database (Denmark)

Tidemand-Lichtenberg, Peter; Kehlet, Louis Martinus; Sanders, Nicolai Højer

2015-01-01

Different schemes for upconversion mid-IR hyperspectral imaging is implemented and compared in terms of spectral coverage, spectral resolution, speed and noise. Phasematch scanning and scanning of the object within the field of view is considered....

The Accuracy of RADIANCE Software in Modelling Overcast Sky Condition

OpenAIRE

Baharuddin

2013-01-01

A validation study of the sky models of RADIANCE simulation software against the overcast sky condition has been carried out in order to test the accuracy of sky model of RADIANCE for modeling the overcast sky condition in Hong Kong. Two sets of data have been analysed. Firstly, data collected from a set of experiments using a physical scale model. In this experiment, the illuminance of four points inside the model was measured under real sky conditions. Secondly, the RADIANCE simulation has ...

Measurements of downwelling far-infrared radiance during the RHUBC-II campaign at Cerro Toco, Chile and comparisons with line-by-line radiative transfer calculations

Science.gov (United States)

Mast, Jeffrey C.; Mlynczak, Martin G.; Cageao, Richard P.; Kratz, David P.; Latvakoski, Harri; Johnson, David G.; Turner, David D.; Mlawer, Eli J.

2017-09-01

Downwelling radiances at the Earth's surface measured by the Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument in an environment with integrated precipitable water (IPW) as low as 0.03 cm are compared with calculated spectra in the far-infrared and mid-infrared. FIRST (a Fourier transform spectrometer) was deployed from August through October 2009 at 5.38 km MSL on Cerro Toco, a mountain in the Atacama Desert of Chile. There FIRST took part in the Radiative Heating in Unexplored Bands Campaign Part 2 (RHUBC-II), the goal of which is the assessment of water vapor spectroscopy. Radiosonde water vapor and temperature vertical profiles are input into the Atmospheric and Environmental Research (AER) Line-by-Line Radiative Transfer Model (LBLRTM) to compute modeled radiances. The LBLRTM minus FIRST residual spectrum is calculated to assess agreement. Uncertainties (1-σ) in both the measured and modeled radiances are also determined. Measured and modeled radiances nearly all agree to within combined (total) uncertainties. Features exceeding uncertainties can be corrected into the combined uncertainty by increasing water vapor and model continuum absorption, however this may not be necessary due to 1-σ uncertainties (68% confidence). Furthermore, the uncertainty in the measurement-model residual is very large and no additional information on the adequacy of current water vapor spectral line or continuum absorption parameters may be derived. Similar future experiments in similarly cold and dry environments will require absolute accuracy of 0.1% of a 273 K blackbody in radiance and water vapor accuracy of ∼3% in the profile layers contributing to downwelling radiance at the surface.

Impact of AIRS radiance in the NCUM 4D-VAR assimilation system

Science.gov (United States)

Srinivas, Desamsetti; Indira Rani, S.; Mallick, Swapan; George, John P.; Sharma, Priti

2016-04-01

The hyperspectral radiances from Atmospheric InfraRed Sounder (AIRS), on board NASA-AQUA satellite, have been processed through the Observation Processing System (OPS) and assimilated in the Variational Assimilation (VAR) System of NCMRWF Unified Model (NCUM). Numerical experiments are conducted in order to study the impact of the AIRS radiance in the NCUM analysis and forecast system. NCMRWF receives AIRS radiance from EUMETCAST through MOSDAC. AIRS is a grating spectrometer having 2378 channels covering the thermal infrared spectrum between 3 and 15 μm. Out of 2378 channels, 324 channels are selected for assimilation according to the peaking of weighting function and meteorological importance. According to the surface type and day-night conditions, some of the channels are not assimilated in the VAR. Observation Simulation Experiments (OSEs) are conducted for a period of 15 days to see the impact of AIRS radiances in NCUM. Statistical parameters like bias and RMSE are calculated to see the real impact of AIRS radiances in the assimilation system. Assimilation of AIRS in the NCUM system reduced the bias and RMSE in the radiances from instruments onboard other satellites. The impact of AIRS is clearly seen in the hyperspectral radiances like IASI and CrIS and also in infrared (HIRS) and microwave (AMSU, ATMS, etc.) sensors.

Effects of Nighttime Light Radiance on the Sleep of the General Population

Science.gov (United States)

Ohayon, Maurice M.; Milesi, Cristina

2015-01-01

The objectives of this study is to verify if the exposure to greater nighttime radiance is associated with changes in the sleep/wake schedule and with greater sleep disturbances. Methods: The target population was the adults (18 years and older) living in California, USA. This represents 24 million of inhabitants. A total of 3,104 subjects participated in the survey (participation rate 85.6%). The participants were interviewed by telephone using the Sleep-EVAL system. The interviews covered several topics including sleeping habits, sleep quality, sleep disturbances, physical symptoms related to menopause. Chronic insomnia was defined as difficulty initiating or maintaining sleep for at least 3 months. Global nighttime light emissions have been collected by the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) sensors. We extracted the radiance calibrated nighttime lights corresponding to the date of the interviews for a three by three window centered on each coordinate corresponding to an interview address. Results: Dissatisfaction with sleep quantity and/or quality was associated with an increased nighttime radiance (p=0.02). Similarly, excessive sleepiness accompanied with impaired functioning was significantly associated with an increased nighttime radiance (p (is) less than 0.0001). The association remained significant after controlling for age, gender and use of a night lamp in the bedroom. Confusional arousals were also significantly associated with an increased nighttime radiance (p (is) less than 0.0001). Bedtime hour was linearly increasing with the intensity of nighttime radiance: the later the bedtime, the greater the nighttime radiance (p (is) less than 0.0001). Similarly, wakeup time became progressively later as the nighttime radiance increased (p (is) less than 0.0001). Both associations remained significant after controlling for age, gender and use of a night lamp in the bedroom. Circadian Rhythm Disorders were the

Target vs. background discrimination using multispectral data in 1.5-14.5 micron

Science.gov (United States)

Cogliandro, Santo; Panizza, Marco; Castelli, Paola

1987-01-01

LOWTRAN V model calculations are compared to experimental spectral background radiance and spectral transmittance data in the 1.5 to 14.5-micron band, in order to identify the most important parameters affecting the discrimination of targets from background. Attention is accordingly given to the IR energy emitted by a reference plate at different values of temperature and emissivity vs various previously investigated backgrounds. Targets at near-ambient temperature are also considered.

Investigation into the mechanisms of time dependent deformation of hard rocks.

CSIR Research Space (South Africa)

Drescher, K

2002-02-01

Full Text Available , very pure spectral and extremely high density level of radiance in the portion of the spectrum extending from UV to microwave. They provide very short light impulses. IR light emitting diodes (LED=s) are a very compact and fairly efficient (4.... A tungsten-halogen lamp with a quartz envelope is a sufficient source of IR radiation for the selected wavelength which radiates about 70 % of power in the IR spectrum up to 4,0 ìm, beyond which their glass envelopes are not transparent. The gas...

Sky glint correction in measurements of upward radiance above the sea surface

Directory of Open Access Journals (Sweden)

Jerzy Olszewski

2000-06-01

Full Text Available An experiment has been performed to determine the upward water-leaving radiance by non-contact measurement of the total upward and downward radiance above the sea surface from a moving ship. The method for achieving this aim is described: the radiance meters are both tilted in such a way that the upward radiance meter can 'see' that part of the measured downward radiance which would be reflected if the water surface were smooth and which is not derived directly from solar glitter. Both meters are firmly fixed in a special frame, which ensures that the required orientation is the most probable one. Time records of the measured parameters are analysed. The results are presented in several forms: frequency (histogram analysis appears to be the most promising one.

Metallicity and the spectral energy distribution and spectral types of dwarf O-stars

NARCIS (Netherlands)

Mokiem, MR; Martin-Hernandez, NL; Lenorzer, A; de Koter, A; Tielens, AGGA

We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of 0 main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used for spectral classification. The spectra are based on

Metallicity and the spectral energy distribution and spectral types of dwarf O-stars

NARCIS (Netherlands)

Mokiem, M.R.; Martín-Hernández, N.L.; Lenorzer, A.; de Koter, A.; Tielens, A.G.G.M.

2004-01-01

We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of O main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used for spectral classification. The spectra are based on

Composite multilobe descriptors for cross-spectral recognition of full and partial face

Science.gov (United States)

Cao, Zhicheng; Schmid, Natalia A.; Bourlai, Thirimachos

2016-08-01

Cross-spectral image matching is a challenging research problem motivated by various applications, including surveillance, security, and identity management in general. An example of this problem includes cross-spectral matching of active infrared (IR) or thermal IR face images against a dataset of visible light images. A summary of recent developments in the field of cross-spectral face recognition by the authors is presented. In particular, it describes the original form and two variants of a local operator named composite multilobe descriptor (CMLD) for facial feature extraction with the purpose of cross-spectral matching of near-IR, short-wave IR, mid-wave IR, and long-wave IR to a gallery of visible light images. The experiments demonstrate that the variants of CMLD outperform the original CMLD and other recently developed composite operators used for comparison. In addition to different IR spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated. Performance of CMLD I to III is evaluated for each of the three cases of distances. The newly developed operators, CMLD I to III, are further utilized to conduct a study on cross-spectral partial face recognition where different facial regions are compared in terms of the amount of useful information they contain for the purpose of conducting cross-spectral face recognition. The experimental results show that among three facial regions considered in the experiments the eye region is the most informative for all IR spectra at all standoff distances.

CORRELATION ANALYSIS OF IR, 1 H- AND 13 C-NMR SPECTRAL DATA OF N-ALKYL AND N-CYCLOALKYL CYANOACETAMIDES

Directory of Open Access Journals (Sweden)

Aleksandar D. Marinković

2011-09-01

Full Text Available Linear free energy relationships (LFER were applied to the IR, 1H- and 13C--NMR spectral data in N-alkyl and N-cycloalkyl cyanoacetamides. N-alkyl and N-cycloalkyl cyanocetamides were synthesized from corresponding amine and ethyl cyanoacetate. A number of substituents were employed for alkyl substitution, and fairly good correlations were obtained, using simple Hammett equation. In N-alkyl and N-cycloalkyl cyanoacetamides substituent cause SCS of N-H hydrogen primarily by steric interaction, polar subtituent effect influences SCS shift of C=O carbon, while steric effect of N-alkyl substituent causes IR stretching frequencies of N-H, C=O and CN group. The conformations of investigated compounds have been studied by the use of semiempirical PM6 method, and together with LFER analysis, give a better insight into the influence of such a structure on the transmission of electronic substituent effects. Negative ρ values for several correlations (reverse substituent effect were found.

Analytically derived conversion of spectral band radiance to brightness temperature

Energy Technology Data Exchange (ETDEWEB)

Berk, Alexander [Spectral Sciences, Inc., 44th Avenue, Burlington, MA 01803 (United States)], E-mail: lex@spectral.com

2008-05-15

Simple analytic expressions for brightness temperature have been derived in terms of band response function spectral moments. Accuracy measures are also derived. Application of these formulas to GOES-12 Sounder thermal infrared bands produces brightness temperature residuals between -5.0 and 2.5 mK for a 150-400 K temperature range. The magnitude of residuals for the five ASTER Radiometer thermal infrared bands over the same temperature range is less than 0.22 mK.

MOPITT Level 1 Radiances V007

Data.gov (United States)

National Aeronautics and Space Administration — The MOPITT Level 1 data product consists of the geolocated, calibrated earth scene radiances, associated instrument engineering data summaries, and inflight...

Calculation of the radiance distribution at the boundary of an isotropically scattering slab

NARCIS (Netherlands)

Doosje, M; Hoenders, B.J; Rinzema, K.

The radiance arising from an anisotropically scattering illuminated stack of n slabs is calulated using the equation of radiative transfer. It appears to be unnecessary to calculate the radiance inside the material; including only the radiance at the boundary surfaces is sufficient to obtain the

ERTS-1 imagery and native plant distributions

Science.gov (United States)

Musick, H. B.; Mcginnies, W.; Haase, E.; Lepley, L. K.

1974-01-01

A method is developed for using ERTS spectral signature data to determine plant community distribution and phenology without resolving individual plants. An Exotech ERTS radiometer was used near ground level to obtain spectral signatures for a desert plant community, including two shrub species, ground covered with live annuals in April and dead ones in June, and bare ground. It is shown that comparisons of scene types can be made when spectral signatures are expressed as a ratio of red reflectivity to IR reflectivity or when they are plotted as red reflectivity vs. IR reflectivity, in which case the signature clusters of each component are more distinct. A method for correcting and converting the ERTS radiance values to reflectivity values for comparison with ground truth data is appended.

Modeling forest defoliation using simulated BRDF and assessing its effect on reflectance and sensor reaching radiance

Science.gov (United States)

Rengarajan, Rajagopalan; Schott, John R.

2016-09-01

Remote sensing techniques such as change detection are widely used for mapping and monitoring forest cover to detect the declining health and vigor of forests. These techniques rely on the assumption that the biophysical variation in the forest introduces a corresponding variation in its reflectance. The biophysical variations are assessed by foresters, but these assessment techniques are expensive and cannot be performed frequently to identify a specific level of change in the forest, for example, infection due to gypsy moths that results in forest defoliation. Further, the interaction of atmosphere, sensor characteristics, and phenology that are inherent in the remotely sensed images makes it difficult to separate biophysical changes from observational effects. We have addressed these limitations by developing a method to model the spectral reflectance properties of forests with varying degrees of defoliation using the Digital Image and Remote Sensing Image Generation (DIRSIG) tool. This paper discusses the in-canopy radiative approach and the impact of defoliation on the reflectance and radiance observed by sensors such as Landsat. The results indicate that the relative variation in forest reflectance between a non-defoliated and a 30% defoliated deciduous forest can be as high as 10% in the NIR spectral band. A function can be fit to predict the level of defoliation from the relative variation in radiance. The modeling and analysis techniques can be extended to assess the impact of atmospheric factors and sensor characteristics relative to the biophysical changes as well as for assessing other biophysical variables in forests.

Third-generation intelligent IR focal plane arrays

Science.gov (United States)

Caulfield, H. John; Jack, Michael D.; Pettijohn, Kevin L.; Schlesselmann, John D.; Norworth, Joe

1998-03-01

SBRC is at the forefront of industry in developing IR focal plane arrays including multi-spectral technology and '3rd generation' functions that mimic the human eye. 3rd generation devices conduct advanced processing on or near the FPA that serve to reduce bandwidth while performing needed functions such as automatic target recognition, uniformity correction and dynamic range enhancement. These devices represent a solution for processing the exorbitantly high bandwidth coming off large area FPAs without sacrificing systems sensitivity. SBRC's two-color approach leverages the company's HgCdTe technology to provide simultaneous multiband coverage, from short through long wave IR, with near theoretical performance. IR systems that are sensitive to different spectral bands achieve enhanced capabilities for target identification and advanced discrimination. This paper will provide a summary of the issues, the technology and the benefits of SBRC's third generation smart and two-color FPAs.

Modeling directional thermal radiance from a forest canopy

International Nuclear Information System (INIS)

McGuire, M.J.; Balick, L.K.; Smith, J.A.; Hutchison, B.A.

1989-01-01

Recent advances in remote sensing technology have increased interest in utilizing the thermal-infared region to gain additional information about surface features such as vegetation canopies. Studies have shown that sensor view angle, canopy structure, and percentage of canopy coverage can affect the response of a thermal sensor. These studies have been primarily of agricultural regions and there have been relatively few examples describing the thermal characteristics of forested regions. This paper describes an extension of an existing thermal vegetation canopy radiance model which has been modified to partially account for the geometrically rough structure of a forest canopy. Fourier series expansion of a canopy height profile is used to calculate improved view factors which partially account for the directional variations in canopy thermal radiance transfers. The original and updated radiance model predictions are compared with experimental data obtained over a deciduous (oak-hickory) forest site. The experimental observations are also used to document azimuthal and nadir directional radiance variations. Maximum angular variations in measured canopy temperatures were 4–6°C (azimuth) and 2.5°C (nadir). Maximum angular variations in simulated temperatures using the modified rough surface model was 4°C. The rough surface model appeared to be sensitive to large gaps in the canopy height profile, which influenced the resultant predicted temperature. (author)

A new theory and its application to remove the effect of surface-reflected light in above-surface radiance data from clear and turbid waters

International Nuclear Information System (INIS)

Dev, Pravin Jeba; Shanmugam, Palanisamy

2014-01-01

Water-leaving radiances (L w ) measured from the deck of a ship or boat in oceanic and lake waters are widely and operationally used for satellite sensor vicarious calibration and validation and development of remote-sensing algorithms to understand interdisciplinary coastal ocean properties and processes. However, accurate determination of L w remains to be a challenging issue because of the limitations of the existing methods to accurately remove the undesired signal (surface-reflected light of the sky and sun) from above-surface measurements of the total upwelling radiance leaving the water surface. In this study, a new theory is developed and applied to the above-surface radiometric data measured from clear, turbid and eutrophic waters. The new method effectively removes surface-reflected contributions from the total upwelling radiance signal under different sky (clear sky to overcast sky) and sun glint conditions. The L w spectra obtained from the above-surface radiance data using the new method are found to match well with those extrapolated from the upwelling radiances (L u ) measured with another set of underwater radiometers (used just below the sea surface). The new method proves to be a viable alternative, especially in circumstances when the above-surface measurements of radiances are severally contaminated by the surface-reflected light fields. Since spectral radiance measurements are also sensitive to the observation angles, and to the magnitude of the radiometer's solid angle field of view, above-surface radiances are also measured for different viewing angles in highly eutrophic waters. Such measurements show large deviations in L w spectra except at lower viewing angles (30°). When applied to these data, the new method eliminates the undesired signal encountered at higher viewing angles and delivers accurate water-leaving radiance data. These results suggest that the new method is capable of removing the surface-reflected light fields from both

Estimation of the Potential Detection of Diatom Assemblages Based on Ocean Color Radiance Anomalies in the North Sea

Directory of Open Access Journals (Sweden)

Anne-Hélène Rêve-Lamarche

2017-12-01

Full Text Available Over the past years, a large number of new approaches in the domain of ocean-color have been developed, leading to a variety of innovative descriptors for phytoplankton communities. One of these methods, named PHYSAT, currently allows for the qualitative detection of five main phytoplankton groups from ocean-color measurements. Even though PHYSAT products are widely used in various applications and projects, the approach is limited by the fact it identifies only dominant phytoplankton groups. This current limitation is due to the use of biomarker pigment ratios for establishing empirical relationships between in-situ information and specific ocean-color radiance anomalies in open ocean waters. However, theoretical explanations of PHYSAT suggests that it could be possible to detect more than dominance cases but move more toward phytoplanktonic assemblage detection. Thus, to evaluate the potential of PHYSAT for the detection of phytoplankton assemblages, we took advantage of the Continuous Plankton Recorder (CPR survey, collected in both the English Channel and the North Sea. The available CPR dataset contains information on diatom abundance in two large areas of the North Sea for the period 1998-2010. Using this unique dataset, recurrent diatom assemblages were retrieved based on classification of CPR samples. Six diatom assemblages were identified in-situ, each having indicators taxa or species. Once this first step was completed, the in-situ analysis was used to empirically associate the diatom assemblages with specific PHYSAT spectral anomalies. This step was facilitated by the use of previous classifications of regional radiance anomalies in terms of shape and amplitude, coupled with phenological tools. Through a matchup exercise, three CPR assemblages were associated with specific radiance anomalies. The maps of detection of these specific radiances anomalies are in close agreement with current in-situ ecological knowledge.

AIS radiometry and the problem of contamination from mixed spectral orders

Science.gov (United States)

Conel, J. E.; Adams, S.; Alley, R. E.; Hoover, G.; Schultz, S.

1988-01-01

The spectral radiance of test areas under solar illumination is ascertained in view of Airborne Imaging Spectrometer (AIS) data from Mono Lake, CA, establishing an atmospheric correction method for major absorbers on the basis of the spectrometric data themselves. The apparent low contrast of all atmospheric absorption bands leads to a study of contamination from overlapping spectral orders in the AIS data; this contamination is found unambiguously above 1500 nm with a magnitude that is a factor of 1.5-2.0 greater than the expected uncontaminated signal alone.

General theory of three-dimensional radiance measurements with optical microprobes RID A-1977-2009

DEFF Research Database (Denmark)

FukshanskyKazarinova, N.; Fukshansky, L.; Kuhl, M.

1997-01-01

Measurements of the radiance distribution and fluence rate within turbid samples with fiber-optic radiance microprobes contain a large variable instrumental error caused by the nonuniform directional sensitivity of the microprobes. A general theory of three-dimensional radiance measurements...

High Resolution Infrared Radiation Sounder (HIRS) for the Nimbus F Spacecraft

Science.gov (United States)

Koenig, E. W.

1975-01-01

Flown on Nimbus F in June 1975, the high resolution infrared radiation sounder (HIRS) scans with a geographical resolution of 23KM and samples radiance in seventeen selected spectral channels from visible (.7 micron) to far IR (15 micron). Vertical temperature profiles and atmospheric moisture content can be inferred from the output. System operation and test results are described.

Spectral reflectance relationships to leaf water stress

Science.gov (United States)

Ripple, William J.

1986-01-01

Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

Calibrated Mid-wave Infrared (IR) (MidIR) and Long-wave IR (LWIR) Stokes and Degree-of-Liner Polarization (DOLP)

Science.gov (United States)

2008-09-01

radiance from natural surfaces, was recorded continuously using an Eppley long-wave pyranometer . The long-wave pyranometer is designed to measure radiance...meteorological parameters as well as the ambient radiant loading experienced during the test recorded by the Eppley long-wave pyranometer . Tables 1

Airborne observations of far-infrared upwelling radiance in the Arctic

Directory of Open Access Journals (Sweden)

Q. Libois

2016-12-01

Full Text Available The first airborne measurements of the Far-InfraRed Radiometer (FIRR were performed in April 2015 during the panarctic NETCARE campaign. Vertical profiles of spectral upwelling radiance in the range 8–50 µm were measured in clear and cloudy conditions from the surface up to 6 km. The clear sky profiles highlight the strong dependence of radiative fluxes to the temperature inversion typical of the Arctic. Measurements acquired for total column water vapour from 1.5 to 10.5 mm also underline the sensitivity of the far-infrared greenhouse effect to specific humidity. The cloudy cases show that optically thin ice clouds increase the cooling rate of the atmosphere, making them important pieces of the Arctic energy balance. One such cloud exhibited a very complex spatial structure, characterized by large horizontal heterogeneities at the kilometre scale. This emphasizes the difficulty of obtaining representative cloud observations with airborne measurements but also points out how challenging it is to model polar clouds radiative effects. These radiance measurements were successfully compared to simulations, suggesting that state-of-the-art radiative transfer models are suited to study the cold and dry Arctic atmosphere. Although FIRR in situ performances compare well to its laboratory performances, complementary simulations show that upgrading the FIRR radiometric resolution would greatly increase its sensitivity to atmospheric and cloud properties. Improved instrument temperature stability in flight and expected technological progress should help meet this objective. The campaign overall highlights the potential for airborne far-infrared radiometry and constitutes a relevant reference for future similar studies dedicated to the Arctic and for the development of spaceborne instruments.

FT-IR Microspectroscopy of Rat Ear Cartilage.

Directory of Open Access Journals (Sweden)

Benedicto de Campos Vidal

Full Text Available Rat ear cartilage was studied using Fourier transform-infrared (FT-IR microspectroscopy to expand the current knowledge which has been established for relatively more complex cartilage types. Comparison of the FT-IR spectra of the ear cartilage extracellular matrix (ECM with published data on articular cartilage, collagen II and 4-chondroitin-sulfate standards, as well as of collagen type I-containing dermal collagen bundles (CBs with collagen type II, was performed. Ear cartilage ECM glycosaminoglycans (GAGs were revealed histochemically and as a reduction in ECM FT-IR spectral band heights (1140-820 cm-1 after testicular hyaluronidase digestion. Although ear cartilage is less complex than articular cartilage, it contains ECM components with a macromolecular orientation as revealed using polarization microscopy. Collagen type II and GAGs, which play a structural role in the stereo-arrangement of the ear cartilage, contribute to its FT-IR spectrum. Similar to articular cartilage, ear cartilage showed that proteoglycans add a contribution to the collagen amide I spectral region, a finding that does not recommend this region for collagen type II quantification purposes. In contrast to articular cartilage, the symmetric stretching vibration of -SO3- groups at 1064 cm-1 appeared under-represented in the FT-IR spectral profile of ear cartilage. Because the band corresponding to the asymmetric stretching vibration of -SO3- groups (1236-1225 cm-1 overlapped with that of amide III bands, it is not recommended for evaluation of the -SO3- contribution to the FT-IR spectrum of the ear cartilage ECM. Instead, a peak (or shoulder at 1027-1016 cm-1 could be better considered for this intent. Amide I/amide II ratios as calculated here and data from the literature suggest that protein complexes of the ear cartilage ECM are arranged with a lower helical conformation compared to pure collagen II. The present results could motivate further studies on this tissue

Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements.

Science.gov (United States)

Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

2017-08-07

A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs (λ). 3C provides a spectrally resolved offset Δ(λ) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction Δ. Correction with Δ(λ) instead of Δ consistently reduced the (mean normalized root-mean-square) deviation between Rrs (λ) and reference reflectances to comparable levels for clear (Δ: 14.3 ± 2.5 %, Δ(λ): 8.2 ± 1.7 %), partly clouded (Δ: 15.4 ± 2.1 %, Δ(λ): 6.5 ± 1.4 %), and completely overcast (Δ: 10.8 ± 1.7 %, Δ(λ): 6.3 ± 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance. Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in a eutrophic freshwater lake in the Netherlands. Rrs (λ) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available.

Broadly tunable picosecond ir source

International Nuclear Information System (INIS)

Campillo, A.J.; Hyer, R.C.; Shapiro, S.L.

1979-01-01

A completely grating tuned (1.9 to 2.4 μm) picosecond traveling wave IR generator capable of controlled spectral bandwidth operation down to the Fourier Transform limit is reported. Subsequent down conversion in CdSe extends tuning to 10 to 20 μm

IASI Radiance Data Assimilation in Local Ensemble Transform Kalman Filter

Science.gov (United States)

Cho, K.; Hyoung-Wook, C.; Jo, Y.

2016-12-01

Korea institute of Atmospheric Prediction Systems (KIAPS) is developing NWP model with data assimilation systems. Local Ensemble Transform Kalman Filter (LETKF) system, one of the data assimilation systems, has been developed for KIAPS Integrated Model (KIM) based on cubed-sphere grid and has successfully assimilated real data. LETKF data assimilation system has been extended to 4D- LETKF which considers time-evolving error covariance within assimilation window and IASI radiance data assimilation using KPOP (KIAPS package for observation processing) with RTTOV (Radiative Transfer for TOVS). The LETKF system is implementing semi operational prediction including conventional (sonde, aircraft) observation and AMSU-A (Advanced Microwave Sounding Unit-A) radiance data from April. Recently, the semi operational prediction system updated radiance observations including GPS-RO, AMV, IASI (Infrared Atmospheric Sounding Interferometer) data at July. A set of simulation of KIM with ne30np4 and 50 vertical levels (of top 0.3hPa) were carried out for short range forecast (10days) within semi operation prediction LETKF system with ensemble forecast 50 members. In order to only IASI impact, our experiments used only conventional and IAIS radiance data to same semi operational prediction set. We carried out sensitivity test for IAIS thinning method (3D and 4D). IASI observation number was increased by temporal (4D) thinning and the improvement of IASI radiance data impact on the forecast skill of model will expect.

Calculation of the angular radiance distribution for a coupled atmosphere and canopy

Science.gov (United States)

Liang, Shunlin; Strahler, Alan H.

1993-01-01

The radiative transfer equations for a coupled atmosphere and canopy are solved numerically by an improved Gauss-Seidel iteration algorithm. The radiation field is decomposed into three components: unscattered sunlight, single scattering, and multiple scattering radiance for which the corresponding equations and boundary conditions are set up and their analytical or iterational solutions are explicitly derived. The classic Gauss-Seidel algorithm has been widely applied in atmospheric research. This is its first application for calculating the multiple scattering radiance of a coupled atmosphere and canopy. This algorithm enables us to obtain the internal radiation field as well as radiances at boundaries. Any form of bidirectional reflectance distribution function (BRDF) as a boundary condition can be easily incorporated into the iteration procedure. The hotspot effect of the canopy is accommodated by means of the modification of the extinction coefficients of upward single scattering radiation and unscattered sunlight using the formulation of Nilson and Kuusk. To reduce the computation for the case of large optical thickness, an improved iteration formula is derived to speed convergence. The upwelling radiances have been evaluated for different atmospheric conditions, leaf area index (LAI), leaf angle distribution (LAD), leaf size and so on. The formulation presented in this paper is also well suited to analyze the relative magnitude of multiple scattering radiance and single scattering radiance in both the visible and near infrared regions.

Spectral filter for splitting a beam with electromagnetic radiation having wavelengths in the extreme ultraviolet (EUV) or soft X-Ray (Soft X) and the infrared (IR) wavelength range

NARCIS (Netherlands)

van Goor, F.A.; Bijkerk, Frederik; van den Boogaard, Toine; van den Boogaard, A.J.R.; van der Meer, R.

2012-01-01

Spectral filter for splitting the primary radiation from a generated beam with primary electromagnetic radiation having a wavelength in the extreme ultraviolet (EUV radiation) or soft X-ray (soft X) wavelength range and parasitic radiation having a wavelength in the infrared wavelength range (IR

Spectral characterization of surface emissivities in the thermal infrared

Science.gov (United States)

Niclòs, Raquel; Mira, Maria; Valor, Enric; Caselles, Diego; García-Santos, Vicente; Caselles, Vicente; Sánchez, Juan M.

2015-04-01

Thermal infrared (TIR) remote sensing trends to hyperspectral sensors on board satellites in the last decades, e.g., the current EOS-MODIS and EOS-ASTER and future missions like HyspIRI, ECOSTRESS, THIRSTY and MISTIGRI. This study aims to characterize spectrally the emissive properties of several surfaces, mostly soils. A spectrometer ranging from 2 to 16 μm, D&P Model 102, has been used to measure samples with singular spectral features, e.g. a sandy soil rich in gypsum sampled in White Sands (New Mexico, USA), salt samples, powdered quartz, and powdered calcite. These samples were chosen for their role in the assessment of thermal emissivity of soils, e.g., the calcite and quartz contents are key variables for modeling TIR emissivities of bare soils, along with soil moisture and organic matter. Additionally, the existence of large areas in the world with abundance of these materials, some of them used for calibration/validation activities of satellite sensors and products, makes the chosen samples interesting. White Sands is the world's largest gypsum dune field encompassing 400 km^2; the salt samples characterize the Salar of Uyuni (Bolivia), the largest salt flat in the world (up to 10,000 km^2), as well as the Jordanian and Israeli salt evaporation ponds at the south end of the Dead Sea, or the evaporation lagoons in Aigües-Mortes (France); and quartz is omnipresent in most of the arid regions of the world such as the Algodones Dunes or Kelso Dunes (California, USA), with areas around 700 km2 and 120 km^2, respectively. Measurements of target leaving radiance, hemispherical radiance reflected by a diffuse reflectance panel, and the radiance from a black body at different temperatures were taken to obtain thermal spectra with the D&P spectrometer. The good consistency observed between our measurements and laboratory spectra of similar samples (ASTER and MODIS spectral libraries) indicated the validity of the measurement protocol. Further, our study showed the

Vacuum Radiance-Temperature Standard Facility for Infrared Remote Sensing at NIM

Science.gov (United States)

Hao, X. P.; Song, J.; Xu, M.; Sun, J. P.; Gong, L. Y.; Yuan, Z. D.; Lu, X. F.

2018-06-01

As infrared remote sensors are very important parts of Earth observation satellites, they must be calibrated based on the radiance temperature of a blackbody in a vacuum chamber prior to launch. The uncertainty of such temperature is thus an essential component of the sensors' uncertainty. This paper describes the vacuum radiance-temperature standard facility (VRTSF) at the National Institute of Metrology of China, which will serve to calibrate infrared remote sensors on Chinese meteorological satellites. The VRTSF can be used to calibrate vacuum blackbody radiance temperature, including those used to calibrate infrared remote sensors. The components of the VRTSF are described in this paper, including the VMTBB, the LNBB, the FTIR spectrometer, the reduced-background optical system, the vacuum chamber used to calibrate customers' blackbody, the vacuum-pumping system and the liquid-nitrogen-support system. The experimental methods and results are expounded. The uncertainty of the radiance temperature of VMTBB is 0.026 °C at 30 °C over 10 μm.

The X-Shooter spectral library

NARCIS (Netherlands)

Chen, Y. P.; Trager, S. C.; Peletier, R. F.; Lançon, A.; Prugniel, Ph.; Koleva, M.

2012-01-01

We are building a new spectral library with the X-Shooter instrument on ESO's VLT: XSL, the X-Shooter Spectral Library. We present our progress in building XSL, which covers the wavelength range from the near-UV to the near-IR with a resolution of R˜10000. As of now we have collected spectra for

MOPITT Beta Level 1 Radiances V107

Data.gov (United States)

National Aeronautics and Space Administration — The MOPITT Beta Level 1 data product consists of the geolocated, calibrated earth scene radiances, associated instrument engineering data summaries, and inflight...

Market analysis, energy savings potential, and future development requirements for Radiance. Final report

Energy Technology Data Exchange (ETDEWEB)

1993-10-01

The Department of Energy (DOE) Office of Conservation and Renewable Energy (CE), Building Equipment Division has funded the development of a sophisticated computer rendering program called Radiance at Lawrence Berkeley Laboratories (LBL). The project review study included: (1) Surveys of the lighting profession to determine how designers would use an improved, user-friendly Radiance, (2) Elucidation of features, including how Radiance could be used to save energy, which could be incorporated into Radiance to facilitate its more widespread use, (3) Outline of a development plan and determination of what costs the DOE might incur if it were to proceed with the development of an improved version, and (4) Weighing the anticipated development costs against anticipated energy-saving benefits.

Evaluation of Daytime Evaporative Fraction from MODIS TOA Radiances Using FLUXNET Observations

Directory of Open Access Journals (Sweden)

Jian Peng

2014-06-01

Full Text Available In recent decades, the land surface temperature/vegetation index (LST/NDVI feature space has been widely used to estimate actual evapotranspiration (ETa or evaporative fraction (EF, defined as the ratio of latent heat flux to surface available energy. Traditionally, it is essential to pre-process satellite top of atmosphere (TOA radiances to obtain LST before estimating EF. However, pre-processing TOA radiances is a cumbersome task including corrections for atmospheric, adjacency and directional effects. Based on the contextual relationship between LST and NDVI, some studies proposed the direct use of TOA radiances instead of satellite retrieved LST products to estimate EF, and found that use of TOA radiances is applicable in some regional studies. The purpose of the present study is to test the robustness of the TOA radiances based EF estimation scheme over different climatic and surface conditions. Flux measurements from 16 FLUXNET (a global network of eddy covariance towers sites were used to validate the Moderate Resolution Imaging Spectro radiometer (MODIS TOA radiances estimated daytime EF. It is found that the EF estimates perform well across a wide variety of climate and biome types—Grasslands, crops, cropland/natural vegetation mosaic, closed shrublands, mixed forest, deciduous broadleaf forest, and savannas. The overall mean bias error (BIAS, mean absolute difference (MAD, root mean square difference (RMSD and correlation coefficient (R values for all the sites are 0.018, 0.147, 0.178 and 0.590, respectively, which are comparable with published results in the literature. We conclude that the direct use of measured TOA radiances instead of LST to estimate daytime EF can avoid complex atmospheric corrections associated with the satellite derived products, and would facilitate the relevant applications where minimum pre-processing is important.

Theory of equidistant three-dimensional radiance measurements with optical microprobes RID A-1977-2009

DEFF Research Database (Denmark)

FukshanskyKazarinova, N.; Fukshansky, L.; Kuhl, Morten

1996-01-01

Fiber-optic radiance microprobes, increasingly applied for measurements of internal light fields in living tissues, provide three-dimensional radiance distribution solids and radiant energy fluence rates at different depths of turbid samples. These data are, however, distorted because of an inher...... of application is presented. The limitations of this theory and the prospects for this approach are discussed....... of an inherent feature of optical fibers: nonuniform angular sensitivity. Because of this property a radiance microprobe during a single measurement partly underestimates light from the envisaged direction and partly senses light from other directions. A theory of three-dimensional equidistant radiance...

Modeling bidirectional radiance measurements collected by the advanced solid-state array spectroradiometer (ASAS) over Oregon transect conifer forests

International Nuclear Information System (INIS)

Abuelgasim, A.A.; Strahler, A.H.

1994-01-01

A geometric-optical model of the bidirectional reflectance of a forest canopy, developed by Li and Strahler, fits observed directional radiance measurements with good accuracy. This model treats the forest cover as a scene of discrete, three-dimensional objects (trees) that are illuminated and viewed from different positions in the hemisphere. The shapes of the objects, their count densities and patterns of placement, are the driving variables, and they condition the mixture of sunlit and shaded objects and background that are observed from a particular viewing direction, given a direction of illumination. This mixture, in turn, controls the brightness apparent to an observer or a radiometric instrument. The Advanced Solid-State Array Spectroradiometer (ASAS) was used to validate this model. This aircraft sensor presently acquires images in 29 spectral bands in the range (465–871 nm) and is pointable fore-and-aft, allowing directional measurements of radiance as a target is approached and imaged at view angles ranging ± 45° from nadir. Through atmospheric correction, ASAS radiances were reduced to bidirectional reflectance factors (BRFs). These were compared to corresponding BRF values computed from the Li-Strahler model using, wherever possible, ground measured component BRFs for calibration. The comparisons showed a good match between the modeled and measured reflectance factors for four of the five Oregon Transect Sites. Thus, the geometric-optical approach provides a realistic model for the bidirectional reflectance distribution function of such natural vegetation canopies. Further modifications are suggested to improve the predicted BRFs and yield still better results. (author)

Observations and Modeling of Atmospheric Radiance Structure

National Research Council Canada - National Science Library

Wintersteiner, Peter

2001-01-01

The overall purpose of the work that we have undertaken is to provide new capabilities for observing and modeling structured radiance in the atmosphere, particularly the non-LTE regions of the atmosphere...

Unmixing of spectral components affecting AVIRIS imagery of Tampa Bay

Science.gov (United States)

Carder, Kendall L.; Lee, Z. P.; Chen, Robert F.; Davis, Curtiss O.

1993-09-01

According to Kirk's as well as Morel and Gentili's Monte Carlo simulations, the popular simple expression, R approximately equals 0.33 bb/a, relating subsurface irradiance reflectance (R) to the ratio of the backscattering coefficient (bb) to absorption coefficient (a), is not valid for bb/a > 0.25. This means that it may no longer be valid for values of remote-sensing reflectance (above-surface ratio of water-leaving radiance to downwelling irradiance) where Rrs4/ > 0.01. Since there has been no simple Rrs expression developed for very turbid waters, we developed one based in part on Monte Carlo simulations and empirical adjustments to an Rrs model and applied it to rather turbid coastal waters near Tampa Bay to evaluate its utility for unmixing the optical components affecting the water- leaving radiance. With the high spectral (10 nm) and spatial (20 m2) resolution of Airborne Visible-InfraRed Imaging Spectrometer (AVIRIS) data, the water depth and bottom type were deduced using the model for shallow waters. This research demonstrates the necessity of further research to improve interpretations of scenes with highly variable turbid waters, and it emphasizes the utility of high spectral-resolution data as from AVIRIS for better understanding complicated coastal environments such as the west Florida shelf.

High-radiance LDP source for mask inspection and beam line applications (Conference Presentation)

Science.gov (United States)

Teramoto, Yusuke; Santos, Bárbara; Mertens, Guido; Kops, Ralf; Kops, Margarete; von Wezyk, Alexander; Bergmann, Klaus; Yabuta, Hironobu; Nagano, Akihisa; Ashizawa, Noritaka; Taniguchi, Yuta; Yamatani, Daiki; Shirai, Takahiro; Kasama, Kunihiko

2017-04-01

High-throughput actinic mask inspection tools are needed as EUVL begins to enter into volume production phase. One of the key technologies to realize such inspection tools is a high-radiance EUV source of which radiance is supposed to be as high as 100 W/mm2/sr. Ushio is developing laser-assisted discharge-produced plasma (LDP) sources. Ushio's LDP source is able to provide sufficient radiance as well as cleanliness, stability and reliability. Radiance behind the debris mitigation system was confirmed to be 120 W/mm2/sr at 9 kHz and peak radiance at the plasma was increased to over 200 W/mm2/sr in the recent development which supports high-throughput, high-precision mask inspection in the current and future technology nodes. One of the unique features of Ushio's LDP source is cleanliness. Cleanliness evaluation using both grazing-incidence Ru mirrors and normal-incidence Mo/Si mirrors showed no considerable damage to the mirrors other than smooth sputtering of the surface at the pace of a few nm per Gpulse. In order to prove the system reliability, several long-term tests were performed. Data recorded during the tests was analyzed to assess two-dimensional radiance stability. In addition, several operating parameters were monitored to figure out which contributes to the radiance stability. The latest model that features a large opening angle was recently developed so that the tool can utilize a large number of debris-free photons behind the debris shield. The model was designed both for beam line application and high-throughput mask inspection application. At the time of publication, the first product is supposed to be in use at the customer site.

The Goddard Snow Radiance Assimilation Project: An Integrated Snow Radiance and Snow Physics Modeling Framework for Snow/cold Land Surface Modeling

Science.gov (United States)

Kim, E.; Tedesco, M.; Reichle, R.; Choudhury, B.; Peters-Lidard C.; Foster, J.; Hall, D.; Riggs, G.

2006-01-01

Microwave-based retrievals of snow parameters from satellite observations have a long heritage and have so far been generated primarily by regression-based empirical "inversion" methods based on snapshots in time. Direct assimilation of microwave radiance into physical land surface models can be used to avoid errors associated with such retrieval/inversion methods, instead utilizing more straightforward forward models and temporal information. This approach has been used for years for atmospheric parameters by the operational weather forecasting community with great success. Recent developments in forward radiative transfer modeling, physical land surface modeling, and land data assimilation are converging to allow the assembly of an integrated framework for snow/cold lands modeling and radiance assimilation. The objective of the Goddard snow radiance assimilation project is to develop such a framework and explore its capabilities. The key elements of this framework include: a forward radiative transfer model (FRTM) for snow, a snowpack physical model, a land surface water/energy cycle model, and a data assimilation scheme. In fact, multiple models are available for each element enabling optimization to match the needs of a particular study. Together these form a modular and flexible framework for self-consistent, physically-based remote sensing and water/energy cycle studies. In this paper we will describe the elements and the integration plan. All modules will operate within the framework of the Land Information System (LIS), a land surface modeling framework with data assimilation capabilities running on a parallel-node computing cluster. Capabilities for assimilation of snow retrieval products are already under development for LIS. We will describe plans to add radiance-based assimilation capabilities. Plans for validation activities using field measurements will also be discussed.

Assessment of Mars Atmospheric Temperature Retrievals from the Thermal Emission Spectrometer Radiances

Science.gov (United States)

Hoffman, Matthew J.; Eluszkiewicz, Janusz; Weisenstein, Deborah; Uymin, Gennady; Moncet, Jean-Luc

2012-01-01

Motivated by the needs of Mars data assimilation. particularly quantification of measurement errors and generation of averaging kernels. we have evaluated atmospheric temperature retrievals from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) radiances. Multiple sets of retrievals have been considered in this study; (1) retrievals available from the Planetary Data System (PDS), (2) retrievals based on variants of the retrieval algorithm used to generate the PDS retrievals, and (3) retrievals produced using the Mars 1-Dimensional Retrieval (M1R) algorithm based on the Optimal Spectral Sampling (OSS ) forward model. The retrieved temperature profiles are compared to the MGS Radio Science (RS) temperature profiles. For the samples tested, the M1R temperature profiles can be made to agree within 2 K with the RS temperature profiles, but only after tuning the prior and error statistics. Use of a global prior that does not take into account the seasonal dependence leads errors of up 6 K. In polar samples. errors relative to the RS temperature profiles are even larger. In these samples, the PDS temperature profiles also exhibit a poor fit with RS temperatures. This fit is worse than reported in previous studies, indicating that the lack of fit is due to a bias correction to TES radiances implemented after 2004. To explain the differences between the PDS and Ml R temperatures, the algorithms are compared directly, with the OSS forward model inserted into the PDS algorithm. Factors such as the filtering parameter, the use of linear versus nonlinear constrained inversion, and the choice of the forward model, are found to contribute heavily to the differences in the temperature profiles retrieved in the polar regions, resulting in uncertainties of up to 6 K. Even outside the poles, changes in the a priori statistics result in different profile shapes which all fit the radiances within the specified error. The importance of the a priori statistics prevents

ENVIRONMENTAL TECHNOLOGY INITIATIVE: CHEMICAL-FREE CLEANING OF SEMICONDUCTORS BY THE RADIANCE PROCESS

Science.gov (United States)

The Radiance Process is a patented dry process for removing contaminants from surfaces. It uses light, usually from a pulsed laser and a gas inert to the surface, to entrain released contaminants. The focus of this effort is to assess the applicability of the Radiance Process t...

Interstitial diffuse radiance spectroscopy of gold nanocages and nanorods in bulk muscle tissues

Directory of Open Access Journals (Sweden)

Grabtchak S

2015-02-01

Full Text Available Serge Grabtchak,1,2 Logan G Montgomery,1 Bo Pang,3,4 Yi Wang,4,5 Chao Zhang,6,7 Zhiyuan Li,6,7 Younan Xia,4,8 William M Whelan1,91Department of Physics, University of Prince Edward Island, Charlottetown, PEI, Canada; 2Departments of Electrical and Computer Engineering, and Physics, Dalhousie University, Halifax, Canada; 3Department of Biomedical Engineering, Peking University, Beijing, People’s Republic of China; 4The Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; 5Key Laboratory of Green Synthesis and Applications, College of Chemistry, Chongqing Normal University, Chongqing, People’s Republic of China; 6Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, People’s Republic of China; 7College of Physics and Optoelectronics, South China University of Technology, Guangzhou, People’s Republic of China; 8School of Chemistry and Biochemistry, and School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA; 9Atlantic Veterinary College, Charlottetown, PEI, CanadaAbstract: Radiance spectroscopy was applied to the interstitial detection of localized inclusions containing Au nanocages or nanorods with various concentrations embedded in porcine muscle phantoms. The radiance was quantified using a perturbation approach, which enabled the separation of contributions from the porcine phantom and the localized inclusion, with the inclusion serving as a perturbation probe of photon distributions in the turbid medium. Positioning the inclusion at various places in the phantom allowed for tracking of photons that originated from a light source, passed through the inclusion’s location, and reached a detector. The inclusions with high extinction coefficients were able to absorb nearly all photons in the range of 650–900 nm, leading to a spectrally flat radiance signal. This signal could be

Profiles of CH4, HDO, H2O, and N2O with improved lower tropospheric vertical resolution from Aura TES radiances

Directory of Open Access Journals (Sweden)

D. Noone

2012-02-01

Full Text Available Thermal infrared (IR radiances measured near 8 microns contain information about the vertical distribution of water vapor (H2O, the water isotopologue HDO, and methane (CH4, key gases in the water and carbon cycles. Previous versions (Version 4 or less of the TES profile retrieval algorithm used a "spectral-window" approach to minimize uncertainty from interfering species at the expense of reduced vertical resolution and sensitivity. In this manuscript we document changes to the vertical resolution and uncertainties of the TES version 5 retrieval algorithm. In this version (Version 5, joint estimates of H2O, HDO, CH4 and nitrous oxide (N2O are made using radiances from almost the entire spectral region between 1100 cm−1 and 1330 cm−1. The TES retrieval constraints are also modified in order to better use this information. The new H2O estimates show improved vertical resolution in the lower troposphere and boundary layer, while the new HDO/H2O estimates can now profile the HDO/H2O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 500 hPa; whereas in previous versions the sensitivity peaked at 200 hPa. However, the upper troposphere methane concentrations are biased high relative to the lower troposphere by approximately 4% on average. This bias is likely related to temperature, calibration, and/or methane spectroscopy errors. This bias can be mitigated by normalizing the CH4 estimate by the ratio of the N2O estimate relative to the N2O prior, under the assumption that the same systematic error affects both the N2O and CH4 estimates. We demonstrate that applying this ratio theoretically reduces the CH4 estimate for non-retrieved parameters that jointly affect both the N2O and CH4 estimates. The relative upper troposphere to lower troposphere bias is approximately 2.8% after this bias

SPATIAL VARIATIONS OF PAH PROPERTIES IN M17SW REVEALED BY SPITZER /IRS SPECTRAL MAPPING

Energy Technology Data Exchange (ETDEWEB)

Yamagishi, M. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Chuo-ku, Sagamihara 252-5210 (Japan); Kaneda, H.; Ishihara, D.; Oyabu, S.; Suzuki, T.; Nishimura, A.; Kohno, M. [Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Onaka, T.; Ohashi, S. [Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nagayama, T.; Matsuo, M. [Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Umemoto, T.; Minamidani, T.; Fujita, S. [Nobeyama Radio Observatory, National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS), 462-2, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305 (Japan); Tsuda, Y., E-mail: yamagish@ir.isas.jaxa.jp [Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-0042 (Japan)

2016-12-20

We present Spitzer /IRS mid-infrared spectral maps of the Galactic star-forming region M17 as well as IRSF/SIRIUS Br γ and Nobeyama 45 m/FOREST {sup 13}CO ( J = 1–0) maps. The spectra show prominent features due to polycyclic aromatic hydrocarbons (PAHs) at wavelengths of 6.2, 7.7, 8.6, 11.3, 12.0, 12.7, 13.5, and 14.2  μ m. We find that the PAH emission features are bright in the region between the H ii region traced by Br γ and the molecular cloud traced by {sup 13}CO, supporting that the PAH emission originates mostly from photo-dissociation regions. Based on the spatially resolved Spitzer /IRS maps, we examine spatial variations of the PAH properties in detail. As a result, we find that the interband ratio of PAH 7.7  μ m/PAH 11.3  μ m varies locally near M17SW, but rather independently of the distance from the OB stars in M17, suggesting that the degree of PAH ionization is mainly controlled by local conditions rather than the global UV environments determined by the OB stars in M17. We also find that the interband ratios of the PAH 12.0  μ m, 12.7  μ m, 13.5  μ m, and 14.2  μ m features to the PAH 11.3  μ m feature are high near the M17 center, which suggests structural changes of PAHs through processing due to intense UV radiation, producing abundant edgy irregular PAHs near the M17 center.

Mid-IR laser system for advanced neurosurgery

Science.gov (United States)

Klosner, M.; Wu, C.; Heller, D. F.

2014-03-01

We present work on a laser system operating in the near- and mid-IR spectral regions, having output characteristics designed to be optimal for cutting various tissue types. We provide a brief overview of laser-tissue interactions and the importance of controlling certain properties of the light beam. We describe the principle of operation of the laser system, which is generally based on a wavelength-tunable alexandrite laser oscillator/amplifier, and multiple Raman conversion stages. This configuration provides robust access to the mid-IR spectral region at wavelengths, pulse energies, pulse durations, and repetition rates that are attractive for neurosurgical applications. We summarize results for ultra-precise selective cutting of nerve sheaths and retinas with little collateral damage; this has applications in procedures such as optic-nerve-sheath fenestration and possible spinal repair. We also report results for cutting cornea, and dermal tissues.

High Spectral Resolution Infrared and Raman Lidar Observations for the ARM Program: Clear and Cloudy Sky Applications

Energy Technology Data Exchange (ETDEWEB)

Revercomb, Henry; Tobin, David; Knuteson, Robert; Borg, Lori; Moy, Leslie

2009-06-17

This grant began with the development of the Atmospheric Emitted Radiance Interferometer (AERI) for ARM. The AERI has provided highly accurate and reliable observations of downwelling spectral radiance (Knuteson et al. 2004a, 2004b) for application to radiative transfer, remote sensing of boundary layer temperature and water vapor, and cloud characterization. One of the major contributions of the ARM program has been its success in improving radiation calculation capabilities for models and remote sensing that evolved from the multi-year, clear-sky spectral radiance comparisons between AERI radiances and line-by-line calculations (Turner et al. 2004). This effort also spurred us to play a central role in improving the accuracy of water vapor measurements, again helping ARM lead the way in the community (Turner et al. 2003a, Revercomb et al. 2003). In order to add high-altitude downlooking AERI-like observations over the ARM sites, we began the development of an airborne AERI instrument that has become known as the Scanning High-resolution Interferometer Sounder (Scanning-HIS). This instrument has become an integral part of the ARM Unmanned Aerospace Vehicle (ARM-UAV) program. It provides both a cross-track mapping view of the earth and an uplooking view from the 12-15 km altitude of the Scaled Composites Proteus aircraft when flown over the ARM sites for IOPs. It has successfully participated in the first two legs of the “grand tour” of the ARM sites (SGP and NSA), resulting in a very good comparison with AIRS observations in 2002 and in an especially interesting data set from the arctic during the Mixed-Phase Cloud Experiment (M-PACE) in 2004.

Iterative discrete ordinates solution of the equation for surface-reflected radiance

Science.gov (United States)

Radkevich, Alexander

2017-11-01

This paper presents a new method of numerical solution of the integral equation for the radiance reflected from an anisotropic surface. The equation relates the radiance at the surface level with BRDF and solutions of the standard radiative transfer problems for a slab with no reflection on its surfaces. It is also shown that the kernel of the equation satisfies the condition of the existence of a unique solution and the convergence of the successive approximations to that solution. The developed method features two basic steps: discretization on a 2D quadrature, and solving the resulting system of algebraic equations with successive over-relaxation method based on the Gauss-Seidel iterative process. Presented numerical examples show good coincidence between the surface-reflected radiance obtained with DISORT and the proposed method. Analysis of contributions of the direct and diffuse (but not yet reflected) parts of the downward radiance to the total solution is performed. Together, they represent a very good initial guess for the iterative process. This fact ensures fast convergence. The numerical evidence is given that the fastest convergence occurs with the relaxation parameter of 1 (no relaxation). An integral equation for BRDF is derived as inversion of the original equation. The potential of this new equation for BRDF retrievals is analyzed. The approach is found not viable as the BRDF equation appears to be an ill-posed problem, and it requires knowledge the surface-reflected radiance on the entire domain of both Sun and viewing zenith angles.

The spectral emissivity of the anode of a carbon arc.

Science.gov (United States)

Schurer, K

1968-03-01

Data in the literature on the spectral emissivity of carbon and graphite show a great divergence, ranging from 0.75 to 0.99 in the visible region. A new determination has been undertaken at a number of wavelengths using an integrating sphere and modulated light. Emissivities ranging from 0.99 in the visible to 0.96 at 0.28 micro and 1.7 micro have been found for several different graphite anodes; the values for lampblack anodes are about 0.005 lower. There is a good agreement with the highest values thus far published. Most of the literature data on the spectral radiance of the anode are consistent with the emissivities found by the present author.

MOPITT Level 1 Radiances HDF file V006

Data.gov (United States)

National Aeronautics and Space Administration — The MOPITT Level 1 data product consists of the geolocated, calibrated earth scene radiances, associated instrument engineering data summaries, and inflight...

Multi-pollutants sensors based on near-IR telecom lasers and mid-IR difference frequency generation: development and applications

International Nuclear Information System (INIS)

Cousin, J.

2006-12-01

At present the detection of VOC and other anthropic trace pollutants is an important challenge in the measurement of air quality. Infrared spectroscopy, allowing spectral regions rich in molecular absorption to be probed, is a suitable technique for in-situ monitoring of the air pollution. Thus the aim of this work was to develop instruments capable of detecting multiple pollutants for in-situ monitoring by IR spectroscopy. A first project benefited from the availability of the telecommunications lasers emitting in near-IR. This instrument was based on an external cavity diode laser (1500 - 1640 nm) in conjunction with a multipass cell (100 m). The detection sensitivity was optimised by employing a balanced detection and a sweep integration procedure. The instrument developed is deployable for in-situ measurements with a sensitivity of -8 cm -1 Hz -1/2 and allowed the quantification of chemical species such as CO 2 , CO, C 2 H 2 , CH 4 and the determination of the isotopic ratio 13 CO 2 / 12 CO 2 in combustion environment The second project consisted in mixing two near-IR fiber lasers in a non-linear crystal (PPLN) in order to produce a laser radiation by difference frequency generation in the middle-IR (3.15 - 3.43 μm), where the absorption bands of the molecules are the most intense. The first studies with this source were carried out on detection of ethylene (C 2 H 4 ) and benzene (C 6 H 6 ). Developments, characterizations and applications of these instruments in the near and middle IR are detailed and the advantages of the 2 spectral ranges is highlighted. (author)

Long-term stability of TES satellite radiance measurements

Directory of Open Access Journals (Sweden)

T. C. Connor

2011-07-01

Full Text Available The utilization of Tropospheric Emission Spectrometer (TES Level 2 (L2 retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window regions of the spectrum. The Global Modeling and Assimilation Office (GMAO profiles for temperature and water vapor and the Real-Time Global Sea Surface Temperature (RTGSST are used as input to the Optimal Spectral Sampling (OSS radiative transfer model to calculate the simulated spectra. The TES reference measurements selected cover a 4-year period of time from mid 2005 through mid 2009 with the selection criteria being; observation latitudes greater than −30° and less than 30°, over ocean, Global Survey mode (nadir view and retrieved cloud optical depth of less than or equal to 0.01. The TES cloud optical depth retrievals are used only for screening purposes and no effects of clouds on the radiances are included in the forward model. This initial screening results in over 55 000 potential reference spectra spanning the four year period. Presented is a trend analysis of the time series of the residuals (observation minus calculations in the TES 2B1, 1B2, 2A1, and 1A1 bands, with the standard deviation of the residuals being approximately equal to 0.6 K for bands 2B1, 1B2, 2A1, and 0.9 K for band 1A1. The analysis demonstrates that the trend in the residuals is not significantly different from zero over the 4-year period. This is one method used to demonstrate that the relative radiometric calibration is stable over time, which is very important for any longer term analysis of TES retrieved products (L2, particularly well-mixed species such as carbon dioxide and methane.

Data fusion of Landsat TM and IRS images in forest classification

Science.gov (United States)

Guangxing Wang; Markus Holopainen; Eero Lukkarinen

2000-01-01

Data fusion of Landsat TM images and Indian Remote Sensing satellite panchromatic image (IRS-1C PAN) was studied and compared to the use of TM or IRS image only. The aim was to combine the high spatial resolution of IRS-1C PAN to the high spectral resolution of Landsat TM images using a data fusion algorithm. The ground truth of the study was based on a sample of 1,020...

Deuterium lamps as transfer standards for spectral radiance measurements

International Nuclear Information System (INIS)

Key, P.J.; Nettleton, D.H.

1985-01-01

This report describes the work carried out at NPL and PTB to improve the performance of a low pressure deuterium discharge lamp, so that it can be used as a transfer standard in the spectral range 120 to 350 nm. To this end it was necessary: - to replace the original quartz windows by magnesium fluoride single crystal plates, which were cut perpendicular to the c-axis of the crystal and which had to be free of impurities, - to construct the lamps in that way that the directional uniformity of the emitted radiation is within the demands, - to age the lamps and to preselect only those of which the irradiance was stable within ± 1% during a thirty minute period after warm-up, - to improve the commercially available electrical power supply to meet the operational needs of the lamps. Thus, the deuterium lamps drifted by about 3% over a period of 100 h at all wavelengths except at 250 nm, where the ageing increased to 4.5%. A liquid nitrogen trap has been developed which can be installed between the vacuum system and the lamp. This reduced to about 2% the decrease of the window's transmission during the first hour of operation, caused by the deposition of oil from the vacuum system

A sphere-scanning radiometer for rapid directional measurements of sky and ground radiance: The PARABOLA field instrument

Science.gov (United States)

Deering, D. W.; Leone, P.

1984-11-01

A unique field instrument, called the PARABOLA, a collapsable support boom, which is self contained and easily transportable to remote sites to enable the acquisition of radiance data for almost the complete (4 pi) sky and ground-looking hemispheres in only 11 seconds was designed. The PARABOLA samples in 15 deg instantaneous field of view sectors in three narrow bandpass spectral channels simultaneously. Field measurement on a variety of earth surface cover types using a truck boom, a specially designed pickup truck mounting system, and a hot air balloon were studied. The PARABOLA instrument has potential for climatological and other studies which require characterization of the distribution of diffuse solar radiation within the sky hemisphere.

Third-harmonic generation in silicon and photonic crystals of macroporous silicon in the spectral intermediate-IR range; Erzeugung der Dritten Harmonischen in Silizium und Photonischen Kristallen aus makroporoesem Silizium im spektralen mittleren IR-Bereich

Energy Technology Data Exchange (ETDEWEB)

Mitzschke, Kerstin

2007-11-01

Nonlinear optical spectroscopy is a powerful method to study surface or bulk properties of condensed matter. In centrosymmetric materials like silicon even order nonlinear optical processes are forbidden. Besides self-focussing or self phase modulation third-harmonic-generation (THG) is the simplest process that can be studied. This work demonstrates that THG is a adapted non-contact and non-invasive optical method to get information about bulk structures of silicon and Photonic crystals (PC), consisting of silicon. Until now most studies are done in the visible spectral range being limited by the linear absorption losses. So the extension of THG to the IR spectral range is extremely useful. This will allow the investigation of Photonic Crystals, where frequencies near a photonic bandgap are of special interest. 2D- photonic structures under investigation were fabricated via photoelectrochemical etching of the Si (100) wafer (thickness 500 {mu}m) receiving square and hexagonal arranged pores. The typical periodicity of the structures used is 2 {mu}m and the length of the pores reached to 400 {mu}m. Because of stability the photonic structures were superimposed on silicon substrate. The experimental set-up used for the THG experiments generates tuneable picosecond IR pulses (tuning range 1500-4000 cm{sup -1}). The IR-pulse hit the sample either perpendicular to the sample surface or under an angle {theta}. The sample can be rotated (f) around the surface normal. The generated third harmonic is analysed by a polarizer, spectrally filtered by a polychromator and registered by a CCD camera. The setup can be used either in transmission or in reflection mode. Optical transmission and reflection spectra of the Si bulk correspond well with the theoretical description, a 4-fold and a 8-fold dependencies of the azimuth angle resulting in the structure of the x{sup (3)}-tensor of (100)-Si. The situation changes dramatically if the PC with hexagonal structure is investigated

Using Fourier transform IR spectroscopy to analyze biological materials

Science.gov (United States)

Baker, Matthew J; Trevisan, Júlio; Bassan, Paul; Bhargava, Rohit; Butler, Holly J; Dorling, Konrad M; Fielden, Peter R; Fogarty, Simon W; Fullwood, Nigel J; Heys, Kelly A; Hughes, Caryn; Lasch, Peter; Martin-Hirsch, Pierre L; Obinaju, Blessing; Sockalingum, Ganesh D; Sulé-Suso, Josep; Strong, Rebecca J; Walsh, Michael J; Wood, Bayden R; Gardner, Peter; Martin, Francis L

2015-01-01

IR spectroscopy is an excellent method for biological analyses. It enables the nonperturbative, label-free extraction of biochemical information and images toward diagnosis and the assessment of cell functionality. Although not strictly microscopy in the conventional sense, it allows the construction of images of tissue or cell architecture by the passing of spectral data through a variety of computational algorithms. Because such images are constructed from fingerprint spectra, the notion is that they can be an objective reflection of the underlying health status of the analyzed sample. One of the major difficulties in the field has been determining a consensus on spectral pre-processing and data analysis. This manuscript brings together as coauthors some of the leaders in this field to allow the standardization of methods and procedures for adapting a multistage approach to a methodology that can be applied to a variety of cell biological questions or used within a clinical setting for disease screening or diagnosis. We describe a protocol for collecting IR spectra and images from biological samples (e.g., fixed cytology and tissue sections, live cells or biofluids) that assesses the instrumental options available, appropriate sample preparation, different sampling modes as well as important advances in spectral data acquisition. After acquisition, data processing consists of a sequence of steps including quality control, spectral pre-processing, feature extraction and classification of the supervised or unsupervised type. A typical experiment can be completed and analyzed within hours. Example results are presented on the use of IR spectra combined with multivariate data processing. PMID:24992094

Signal-to-noise ratio of FT-IR CO gas spectra

DEFF Research Database (Denmark)

Bak, J.; Clausen, Sønnik

1999-01-01

in emission and transmission spectrometry, an investigation of the SNR in CO gas spectra as a function of spectral resolution has been carried out. We present a method to (1) determine experimentally the SNR at constant throughput, (2) determine the SNR on the basis of measured noise levels and Hitran......The minimum amount of a gaseous compound which can be detected and quantified with Fourier transform infrared (FT-IR) spectrometers depends on the signal-to-noise ratio (SNR) of the measured gas spectra. In order to use low-resolution FT-IR spectrometers to measure combustion gases like CO and CO2...... simulated signals, and (3) determine the SNR of CO from high to low spectral resolutions related to the molecular linewidth and vibrational-rotational lines spacing. In addition, SNR values representing different spectral resolutions but scaled to equal measurement times were compared. It was found...

Linearly Polarized IR Spectroscopy Theory and Applications for Structural Analysis

CERN Document Server

Kolev, Tsonko

2011-01-01

A technique that is useful in the study of pharmaceutical products and biological molecules, polarization IR spectroscopy has undergone continuous development since it first emerged almost 100 years ago. Capturing the state of the science as it exists today, "Linearly Polarized IR Spectroscopy: Theory and Applications for Structural Analysis" demonstrates how the technique can be properly utilized to obtain important information about the structure and spectral properties of oriented compounds. The book starts with the theoretical basis of linear-dichroic infrared (IR-LD) spectroscop

Equivalent Sensor Radiance Generation and Remote Sensing from Model Parameters. Part 1; Equivalent Sensor Radiance Formulation

Science.gov (United States)

Wind, Galina; DaSilva, Arlindo M.; Norris, Peter M.; Platnick, Steven E.

2013-01-01

In this paper we describe a general procedure for calculating equivalent sensor radiances from variables output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint the algorithm takes explicit account of the model subgrid variability, in particular its description of the probably density function of total water (vapor and cloud condensate.) The equivalent sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies. We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products.) We focus on clouds and cloud/aerosol interactions, because they are very important to model development and improvement.

MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km V006

Data.gov (United States)

National Aeronautics and Space Administration — The MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km (MOD021KM) contains calibrated and geolocated at-aperture radiances for 36 discrete bands located in the 0.4...

CAMEX-3 ATMOSPHERIC EMITTED RADIANCE INTERFEROMETER (AERI) V1

Data.gov (United States)

National Aeronautics and Space Administration — The Atmospheric Emitted Radiance Interferometer (AERI) was used to make atmospheric temperature and moisture retrievals. AERI provides absolutely calibrated...

ASTER L2 Surface Radiance TIR V003

Data.gov (United States)

National Aeronautics and Space Administration — The ASTER L2 Surface Radiance TIR is an on-demand product generated using the five thermal infra-red (TIR) Bands (acquired either during the day or night time)...

Characterization and identification of microorganisms by FT-IR microspectrometry

Science.gov (United States)

Ngo-Thi, N. A.; Kirschner, C.; Naumann, D.

2003-12-01

We report on a novel FT-IR approach for microbial characterization/identification based on a light microscope coupled to an infrared spectrometer which offers the possibility to acquire IR-spectra of microcolonies containing only few hundred cells. Microcolony samples suitable for FT-IR microspectroscopic measurements were obtained by a replica technique with a stamping device that transfers spatially accurate cells of microcolonies growing on solid culture plates to a special, IR-transparent or reflecting stamping plate. High quality spectra could be recorded either by applying the transmission/absorbance or the reflectance/absorbance mode of the infrared microscope. Signal to noise ratios higher than 1000 were obtained for microcolonies as small as 40 μm in diameter. Reproducibility levels were established that allowed species and strain identification. The differentiation and classification capacity of the FT-IR microscopic technique was tested for different selected microorganisms. Cluster and factor analysis methods were used to evaluate the complex spectral data. Excellent discrimination between bacteria and yeasts, and at the same time Gram-negative and Gram-positive bacterial strains was obtained. Twenty-two selected strains of different species within the genus Staphylococcus were repetitively measured and could be grouped into correct species cluster. Moreover, the results indicated that the method allows also identifications at the subspecies level. Additionally, the new approach allowed spectral mapping analysis of single colonies which provided spatially resolved characterization of growth heterogeneity within complex microbial populations such as colonies.

Application of FT-IR spectroscopy on breast cancer serum analysis

Science.gov (United States)

Elmi, Fatemeh; Movaghar, Afshin Fayyaz; Elmi, Maryam Mitra; Alinezhad, Heshmatollah; Nikbakhsh, Novin

2017-12-01

Breast cancer is regarded as the most malignant tumor among women throughout the world. Therefore, early detection and proper diagnostic methods have been known to help save women's lives. Fourier Transform Infrared (FT-IR) spectroscopy, coupled with PCA-LDA analysis, is a new technique to investigate the characteristics of serum in breast cancer. In this study, 43 breast cancer and 43 healthy serum samples were collected, and the FT-IR spectra were recorded for each one. Then, PCA analysis and linear discriminant analysis (LDA) were used to analyze the spectral data. The results showed that there were differences between the spectra of the two groups. Discriminating wavenumbers were associated with several spectral differences over the 950-1200 cm- 1(sugar), 1190-1350 cm- 1 (collagen), 1475-1710 cm- 1 (protein), 1710-1760 cm- 1 (ester), 2800-3000 cm- 1 (stretching motions of -CH2 & -CH3), and 3090-3700 cm- 1 (NH stretching) regions. PCA-LDA performance on serum IR could recognize changes between the control and the breast cancer cases. The diagnostic accuracy, sensitivity, and specificity of PCA-LDA analysis for 3000-3600 cm- 1 (NH stretching) were found to be 83%, 84%, 74% for the control and 80%, 76%, 72% for the breast cancer cases, respectively. The results showed that the major spectral differences between the two groups were related to the differences in protein conformation in serum samples. It can be concluded that FT-IR spectroscopy, together with multivariate data analysis, is able to discriminate between breast cancer and healthy serum samples.

Liver Status Assessment by Spectrally and Time Resolved IR Detection of Drug Induced Breath Gas Changes

Directory of Open Access Journals (Sweden)

Tom Rubin

2016-05-01

Full Text Available The actual metabolic capacity of the liver is crucial for disease identification, liver therapy, and liver tumor resection. By combining induced drug metabolism and high sensitivity IR spectroscopy of exhaled air, we provide a method for quantitative liver assessment at bedside within 20 to 60 min. Fast administration of 13C-labelled methacetin induces a fast response of liver metabolism and is tracked in real-time by the increase of 13CO2 in exhaled air. The 13CO2 concentration increase in exhaled air allows the determination of the metabolic liver capacity (LiMAx-test. Fluctuations in CO2 concentration, pressure and temperature are minimized by special gas handling, and tracking of several spectrally resolved CO2 absorption bands with a quantum cascade laser. Absorption measurement of different 12CO2 and 13CO2 rotation-vibration transitions in the same time window allows for multiple referencing and reduction of systematic errors. This FLIP (Fast liver investigation package setup is being successfully used to plan operations and determine the liver status of patients.

A Microwave Radiance Assimilation Study for a Tundra Snowpack

Science.gov (United States)

Kim, Edward; Durand, Michael; Margulis, Steve; England, Anthony

2010-01-01

Recent studies have begun exploring the assimilation of microwave radiances for the modeling and retrieval of snow properties. At a point scale, and for short durations (i week), radiance assimilation (RA) results are encouraging. However, in order to determine how practical RA might be for snow retrievals when applied over longer durations, larger spatial scales, and/or different snow types, we must expand the scope of the tests. In this paper we use coincident microwave radiance measurements and station data from a tundra site on the North Slope of Alaska. The field data are from the 3rd Radio-brightness Energy Balance Experiment (REBEX-3) carried out in 1994-95 by the University of Michigan. This dataset will provide a test of RA over months instead of one week, and for a very different type of snow than previous snow RA studies. We will address the following questions: flow well can a snowpack physical model (SM), forced with local weather, match measured conditions for a tundra snowpack?; How well can a microwave emission model, driven by the snowpack model, match measured microwave brightnesses for a tundra snowpack?; How well does RA increase or decrease the fidelity of estimates of snow depth and temperatures for a tundra snowpack?

Preliminary Geologic/spectral Analysis of LANDSAT-4 Thematic Mapper Data, Wind River/bighorn Basin Area, Wyoming

Science.gov (United States)

Lang, H. R.; Conel, J. E.; Paylor, E. D.

1984-01-01

A LIDQA evaluation for geologic applications of a LANDSAT TM scene covering the Wind River/Bighorn Basin area, Wyoming, is examined. This involves a quantitative assessment of data quality including spatial and spectral characteristics. Analysis is concentrated on the 6 visible, near infrared, and short wavelength infrared bands. Preliminary analysis demonstrates that: (1) principal component images derived from the correlation matrix provide the most useful geologic information. To extract surface spectral reflectance, the TM radiance data must be calibrated. Scatterplots demonstrate that TM data can be calibrated and sensor response is essentially linear. Low instrumental offset and gain settings result in spectral data that do not utilize the full dynamic range of the TM system.

Extending laser plasma accelerators into the mid-IR spectral domain with a next-generation ultra-fast CO2 laser

Science.gov (United States)

Pogorelsky, I. V.; Babzien, M.; Ben-Zvi, I.; Polyanskiy, M. N.; Skaritka, J.; Tresca, O.; Dover, N. P.; Najmudin, Z.; Lu, W.; Cook, N.; Ting, A.; Chen, Y.-H.

2016-03-01

Expanding the scope of relativistic plasma research to wavelengths longer than the λ/≈   0.8-1.1 μm range covered by conventional mode-locked solid-state lasers would offer attractive opportunities due to the quadratic scaling of the ponderomotive electron energy and critical plasma density with λ. Answering this quest, a next-generation mid-IR laser project is being advanced at the BNL ATF as a part of the user facility upgrade. We discuss the technical approach to this conceptually new 100 TW, 100 fs, λ  =   9-11 μm CO2 laser BESTIA (Brookhaven Experimental Supra-Terawatt Infrared at ATF) that encompasses several innovations applied for the first time to molecular gas lasers. BESTIA will enable new regimes of laser plasma accelerators. One example is shock-wave ion acceleration (SWA) from gas jets. We review ongoing efforts to achieve stable, monoenergetic proton acceleration by dynamically shaping the plasma density profile from a hydrogen gas target with laser-produced blast waves. At its full power, 100 TW BESTIA promises to achieve proton beams at an energy exceeding 200 MeV. In addition to ion acceleration in over-critical plasma, the ultra-intense mid-IR BESTIA will open up new opportunities in driving wakefields in tenuous plasmas, expanding the landscape of laser wakefield accelerator (LWFA) studies into the unexplored long-wavelength spectral domain. Simple wavelength scaling suggests that a 100 TW CO2 laser beam will be capable of efficiently generating plasma ‘bubbles’ a thousand times greater in volume compared with a near-IR solid state laser of an equivalent power. Combined with a femtosecond electron linac available at the ATF, this wavelength scaling will facilitate the study of external seeding and staging of LWFAs.

AN UNBIASED SPECTRAL LINE SURVEY TOWARD R CrA IRS7B IN THE 345 GHz WINDOW WITH ASTE

International Nuclear Information System (INIS)

Watanabe, Yoshimasa; Sakai, Nami; Yamamoto, Satoshi; Lindberg, Johan E.; Bisschop, Suzanne E.; Jørgensen, Jes K.

2012-01-01

We have conducted a spectral line survey in the 332-364 GHz region with the Atacama Submillimeter Telescope Experiment 10 m telescope toward R CrA IRS7B, a low-mass protostar in the Class 0 or Class 0/I transitional stage. We have also performed some supplementary observations in the 450 GHz band. In total, 16 molecular species are identified in the 332-364 GHz region. Strong emission lines of CN and CCH are observed, whereas complex organic molecules and long carbon-chain molecules, which are characteristics of hot corino and warm carbon-chain chemistry (WCCC) source, respectively, are not detected. The rotation temperature of CH 3 OH is evaluated to be 31 K, which is significantly lower than that reported for the prototypical hot corino IRAS 16293-2422 (∼85 K). The deuterium fractionation ratios for CCH and H 2 CO are obtained to be 0.038 and 0.050, respectively, which are much lower than those in the hot corino. These results suggest a weak hot corino activity in R CrA IRS7B. On the other hand, the carbon-chain related molecules, CCH and c-C 3 H 2 , are found to be abundant. However, this source cannot be classified as a WCCC source, since long carbon-chain molecules are not detected. If WCCC and hot corino chemistry represent the two extremes in chemical compositions of low-mass Class 0 sources, R CrA IRS7B would be a source with a mixture of these two chemical characteristics. The UV radiation from the nearby Herbig Ae star R CrA may also affect the chemical composition. The present line survey demonstrates further chemical diversity in low-mass star-forming regions.

FT-IR spectroscopy of lipoproteins—A comparative study

Science.gov (United States)

Krilov, Dubravka; Balarin, Maja; Kosović, Marin; Gamulin, Ozren; Brnjas-Kraljević, Jasminka

2009-08-01

FT-IR spectra, in the frequency region 4000-600 cm -1, of four major lipoprotein classes: very low density lipoprotein (VLDL), low density lipoprotein (LDL) and two subclasses of high density lipoproteins (HDL 2 and HDL 3) were analyzed to obtain their detailed spectral characterization. Information about the protein domain of particle was obtained from the analysis of amide I band. The procedure of decomposition and curve fitting of this band confirms the data already known about the secondary structure of two different apolipoproteins: apo A-I in HDL 2 and HDL 3 and apo B-100 in LDL and VLDL. For information about the lipid composition and packing of the particular lipoprotein the well expressed lipid bands in the spectra were analyzed. Characterization of spectral details in the FT-IR spectrum of natural lipoprotein is necessary to study the influence of external compounds on its structure.

Infrared (IR) photon-sensitive spectromicroscopy in a cryogenic environment

Science.gov (United States)

Pereverzev, Sergey

2016-06-14

A system designed to suppress thermal radiation background and to allow IR single-photon sensitive spectromicroscopy of small samples by using both absorption, reflection, and emission/luminescence measurements. The system in one embodiment includes: a light source; a plurality of cold mirrors configured to direct light along a beam path; a cold or warm sample holder in the beam path; windows of sample holder (or whole sample holder) are transparent in a spectral region of interest, so they do not emit thermal radiation in the same spectral region of interest; a cold monochromator or other cold spectral device configured to direct a selected fraction of light onto a cold detector; a system of cold apertures and shields positioned along the beam path to prevent unwanted thermal radiation from arriving at the cold monochromator and/or the detector; a plurality of optical, IR and microwave filters positioned along the beam path and configured to adjust a spectral composition of light incident upon the sample under investigation and/or on the detector; a refrigerator configured to maintain the detector at a temperature below 1.0K; and an enclosure configured to: thermally insulate the light source, the plurality of mirrors, the sample holder, the cold monochromator and the refrigerator.

SPECTRAL COLOR INDICES BASED GEOSPATIAL MODELING OF SOIL ORGANIC MATTER IN CHITWAN DISTRICT, NEPAL

Directory of Open Access Journals (Sweden)

U. K. Mandal

2016-06-01

Full Text Available Space Technology provides a resourceful-cost effective means to assess soil nutrients essential for soil management plan. Soil organic matter (SOM is one of valuable controlling productivity of crops by providing nutrient in farming systems. Geospatial modeling of soil organic matter is essential if there is unavailability of soil test laboratories and its strong spatial correlation. In the present analysis, soil organic matter is modeled from satellite image derived spectral color indices. Brightness Index (BI, Coloration Index (CI, Hue Index (HI, Redness Index (RI and Saturation Index (SI were calculated by converting DN value to radiance and radiance to reflectance from Thematic Mapper image. Geospatial model was developed by regressing SOM with color indices and producing multiple regression model using stepwise regression technique. The multiple regression equation between SOM and spectral indices was significant with R = 0. 56 at 95% confidence level. The resulting MLR equation was then used for the spatial prediction for the entire study area. Redness Index was found higher significance in estimating the SOM. It was used to predict SOM as auxiliary variables using cokringing spatial interpolation technique. It was tested in seven VDCs of Chitwan district of Nepal using Thematic Mapper remotely sensed data. SOM was found to be measured ranging from 0.15% to 4.75 %, with a mean of 2.24 %. Remotely sensed data derived spectral color indices have the potential as useful auxiliary variables for estimating SOM content to generate soil fertility management plans.

Model for the angular distribution of sky radiance

Energy Technology Data Exchange (ETDEWEB)

Hooper, F C; Brunger, A P

1979-08-01

A flexible mathematical model is introduced which describes the radiance of the dome of the sky under various conditions. This three-component continuous distribution (TCCD) model is compounded by the superposition of three separate terms, the isotropic, circumsolar and horizon brightening terms, each representing the contribution of a particular sky characteristic. In use a particular sky condition is characterized by the values of the coefficients of each of these three terms, defining the distribution of the total diffuse component. The TCCD model has been demonstrated to fit both the normalized clear sky data and the normalized overcast sky data with an RMS error of about ten percent of the man overall sky radiance. By extension the model could describe variable or partly clouded sky conditions. The model can aid in improving the prediction of solar collector performance.

A New Algorithm for Detecting Cloud Height using OMPS/LP Measurements

Science.gov (United States)

Chen, Zhong; DeLand, Matthew; Bhartia, Pawan K.

2016-01-01

The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) ozone product requires the determination of cloud height for each event to establish the lower boundary of the profile for the retrieval algorithm. We have created a revised cloud detection algorithm for LP measurements that uses the spectral dependence of the vertical gradient in radiance between two wavelengths in the visible and near-IR spectral regions. This approach provides better discrimination between clouds and aerosols than results obtained using a single wavelength. Observed LP cloud height values show good agreement with coincident Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements.

Temperature profiles of an ablation controlled arc in PTFE: II. Simulation of side-on radiances

International Nuclear Information System (INIS)

Schneidenbach, H; Uhrlandt, D; Franke, St; Seeger, M

2007-01-01

The temperature determination by spectroscopic measurements in high-current high-pressure arcs in a polytetrafluoroethylene (PTFE) nozzle under the assumption of an optically thin plasma has been investigated. Assuming local thermodynamic equilibrium the radial temperature distributions as well as the plasma pressures have been determined by fitting a model to measured spectral radiances considering line and continuum absorption. It is shown that absorption has to be included in the error estimate of the experimental results. The different effects, which cause deviations from the optically thin case, have been analysed numerically and by using a simplified analytical model. The theoretically estimated pressures sensitively depend on the Stark broadening. In the studied plasmas the calculated large electron densities indicate a marked reduction of the Stark widths by nonideality effects. The applicability of the experimental method has been proved for suitably chosen lines

Estimating nocturnal opaque ice cloud optical depth from MODIS multispectral infrared radiances using a neural network method

Science.gov (United States)

Minnis, Patrick; Hong, Gang; Sun-Mack, Szedung; Smith, William L.; Chen, Yan; Miller, Steven D.

2016-05-01

Retrieval of ice cloud properties using IR measurements has a distinct advantage over the visible and near-IR techniques by providing consistent monitoring regardless of solar illumination conditions. Historically, the IR bands at 3.7, 6.7, 11.0, and 12.0 µm have been used to infer ice cloud parameters by various methods, but the reliable retrieval of ice cloud optical depth τ is limited to nonopaque cirrus with τ < 8. The Ice Cloud Optical Depth from Infrared using a Neural network (ICODIN) method is developed in this paper by training Moderate Resolution Imaging Spectroradiometer (MODIS) radiances at 3.7, 6.7, 11.0, and 12.0 µm against CloudSat-estimated τ during the nighttime using 2 months of matched global data from 2007. An independent data set comprising observations from the same 2 months of 2008 was used to validate the ICODIN. One 4-channel and three 3-channel versions of the ICODIN were tested. The training and validation results show that IR channels can be used to estimate ice cloud τ up to 150 with correlations above 78% and 69% for all clouds and only opaque ice clouds, respectively. However, τ for the deepest clouds is still underestimated in many instances. The corresponding RMS differences relative to CloudSat are ~100 and ~72%. If the opaque clouds are properly identified with the IR methods, the RMS differences in the retrieved optical depths are ~62%. The 3.7 µm channel appears to be most sensitive to optical depth changes but is constrained by poor precision at low temperatures. A method for estimating total optical depth is explored for estimation of cloud water path in the future. Factors affecting the uncertainties and potential improvements are discussed. With improved techniques for discriminating between opaque and semitransparent ice clouds, the method can ultimately improve cloud property monitoring over the entire diurnal cycle.

IR technology for enhanced force protection by AIM

Science.gov (United States)

Breiter, R.; Ihle, T.; Rode, W.; Wendler, J.; Rühlich, I.; Haiml, M.; Ziegler, J.

2008-04-01

In all recent missions our forces are faced with various types of asymmetric threads like snipers, IEDs, RPGs or MANPADS. 2 nd and 3 rd Gen IR technology is a backbone of modern force protection by providing situational awareness and accurate target engagement at day/night. 3 rd Gen sensors are developed for thread warning capabilities by use of spectral or spatial information. The progress on a dual-color IR module is discussed in a separate paper [1]. A 1024x256 SWIR array with flexure bearing compressor and pulse tube cold finger provides > 50,000h lifetime for space or airborne hyperspectral imaging in pushbroom geometry with 256 spectral channels for improved change detection and remote sensing of IEDs or chemical agents. Similar concepts are pursued in the LWIR with either spectroscopic imaging or a system of LWIR FPA combined with a cooled tunable Laser to do spectroscopy with stimulated absorption of specific wavelengths. AIM introduced the RangIR sight to match the requirements of sniper teams, AGLs and weapon stations, extending the outstanding optronic performance of the fielded HuntIR with position data of a target by a laser range finder (LRF), a 3 axis digital magnetic compass (DMC) and a ballistic computer for accurate engagement of remote targets. A version with flexure bearing cooler with >30,000h life time is being developed for continuous operation in e.g. gunfire detection systems. This paper gives an overview of AIM's technologies for enhanced force protection.

Functional Form of the Radiometric Equation for the SNPP VIIRS Reflective Solar Bands: An Initial Study

Science.gov (United States)

Lei, Ning; Xiong, Xiaoxiong

2016-01-01

The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite is a passive scanning radiometer and an imager, observing radiative energy from the Earth in 22 spectral bands from 0.41 to 12 microns which include 14 reflective solar bands (RSBs). Extending the formula used by the Moderate Resolution Imaging Spectroradiometer instruments, currently the VIIRS determines the sensor aperture spectral radiance through a quadratic polynomial of its detector digital count. It has been known that for the RSBs the quadratic polynomial is not adequate in the design specified spectral radiance region and using a quadratic polynomial could drastically increase the errors in the polynomial coefficients, leading to possible large errors in the determined aperture spectral radiance. In addition, it is very desirable to be able to extend the radiance calculation formula to correctly retrieve the aperture spectral radiance with the level beyond the design specified range. In order to more accurately determine the aperture spectral radiance from the observed digital count, we examine a few polynomials of the detector digital count to calculate the sensor aperture spectral radiance.

Ice contamination on satellite IR sensors: the MIPAS case

Science.gov (United States)

Niro, F.; Fehr, T.; Kleinert, A.; Laur, H.; Lecomte, P.; Perron, G.

2009-04-01

MIPAS on board the ENVISAT platform is a Michelson Interferometer measuring the atmospheric limb emission in the mid-infrared (IR), from 4.15 µm to 14.5 µm [1]. The calibrated MIPAS measurements are radiance spectra as a function of wavenumber. The radiometric and spectral calibrations of the raw data are part of the Level 1 processing in the Ground Segment [2]. The accuracy of the radiometric calibration is essential in order to ensure precise temperature and trace gas retrieval in the Level 2 processing. This calibration process requires a set of cold space measurements and a series of measurements of a black body source to determine the radiometric gain function and to correct for instrument self-emission. The deep space measurements are repeated every four limb scanning sequences with the purpose of compensating the variation of instrument's temperature along the orbit. The radiometric gain function is updated every week to correct for a degraded transmission at the detector due to ice contamination. The ice contamination leads to a decrease of the signal, mainly due to ice absorption of the incoming IR radiation. This paper presents an analysis of the effect of ice contamination during the MIPAS mission; in particular we will study its impact on the radiometric accuracy and on the Level 2 retrieval precision. We will highlight the importance of the ice monitoring for the MIPAS mission and we will show that this type of monitoring allows improving the stability and the overall performances of the MIPAS instrument. The effect of ice in other ENVISAT instruments will be also mentioned (e.g., AATSR). The lessons learned during the mission about ice contamination are very important, especially for IR sensors that are the most affected by this type of problem. These lessons will be useful in order to improve the in-flight operations of present and future satellite missions. [1] H. Fischer, M. Birk, C. Blom, B. Carli, M. Carlotti, T. von Clarmann, L. Delbouille, A

Mid-IR Reflectance (DRIFT) Spectral Variations in Basaltic Mineralogy with Direction of Impact at Lonar Crater, India

Science.gov (United States)

Basavaiah, N.; Chavan, R. S.; Arif, M.

2012-12-01

Identification of spectral changes with the direction of impact has important implications for understanding the impact cratering phenomenon occurring on both terrestrial and extraterrestrial planets and also for geology of the crater. Fortuitously, Lonar Impact Crater (India) is the only well-preserved terrestrial simple crater excavated on Deccan basalts and serves as an excellent analogue to craters on Mars and Moon. An ~570 ka old Lonar crater was suggested to be formed by an oblique impact of a chondritic impactor that struck the pre-impact target from the east into a sequence of six basaltic Deccan flows and created a 1.88 km diameter crater with two layers of ejecta blanket. Here we report preliminary laboratory studies of spectral results on fine-grained rock powers (IR (4000-400 cm-1) Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The basalts were collected from two profiles in the east and south sections of the crater wall and the upper most crater rim, which later subdivided into sector-wise samples to carry out a systematic study of spectral properties of Lonar basalts, together with impact related samples of breccias and impact melts. For the first time, data of the shock metamorphism of Lonar basalt is examined using DRIFT spectroscopy. Infrared spectra of rock powders of relatively unshocked and shocked basalts are obtained to document the mineralogical variations and the distribution of primary (e.g. Plagioclase Feldspar, Pyroxene), and secondary Phyllosilicate minerals (e.g. Illite, Smectite, Montmorillonite, Saponite, Serpentine) with direction of impact. The spectral data between pre-impact unshocked and post-impact shocked basalts are interpreted to reflect the effect of shock pressure and alteration that rock have undergone. On western crater rim sector, typical silicate spectral features in 900-1200 cm-1 which attributed to Si-O stretching, are observed to change slightly in the width and shift in position as a result of

Spectral Light Measurements in Microbenthic Phototrophic Communities with a Fiberoptic Microprobe Coupled to a Sensitive Diode-Array Detector Rid A-1977-2009

DEFF Research Database (Denmark)

KUHL, M.; JØRGENSEN, BB

1992-01-01

with microelectrode measurements of oxygenic photosynthesis in the coastal sediment. With an incident light intensity of 200 muEinst m-2 s-1, photon scalar irradiance reached a maximum of 283 muEinst m-2 s-1 at the sediment surface. The lower boundary of the euphotic zone was 2.2 mm below the surface at a light......A diode array detector system for microscale light measurements with fiber-optic microprobes was developed; it measures intensities of 400-900-nm light over >6 orders of magnitude with a spectral resolution of 2-5 nm. Fiber-optic microprobes to measure field radiance or scalar irradiance were...... extinction maxima in measured radiance spectra at 430-550 nm (Chl a and carotenoids), 620-625 nm (phycocyanin), 675 nm (Chl a), 745-750 nm (BChl c), 800-810 nm, and 860-880 nm (BChl a). Scalar irradiance spectra exhibited a different spectral composition and a higher light intensity at the sediment surface...

Hyperspectral material identification on radiance data using single-atmosphere or multiple-atmosphere modeling

Science.gov (United States)

Mariano, Adrian V.; Grossmann, John M.

2010-11-01

Reflectance-domain methods convert hyperspectral data from radiance to reflectance using an atmospheric compensation model. Material detection and identification are performed by comparing the compensated data to target reflectance spectra. We introduce two radiance-domain approaches, Single atmosphere Adaptive Cosine Estimator (SACE) and Multiple atmosphere ACE (MACE) in which the target reflectance spectra are instead converted into sensor-reaching radiance using physics-based models. For SACE, known illumination and atmospheric conditions are incorporated in a single atmospheric model. For MACE the conditions are unknown so the algorithm uses many atmospheric models to cover the range of environmental variability, and it approximates the result using a subspace model. This approach is sometimes called the invariant method, and requires the choice of a subspace dimension for the model. We compare these two radiance-domain approaches to a Reflectance-domain ACE (RACE) approach on a HYDICE image featuring concealed materials. All three algorithms use the ACE detector, and all three techniques are able to detect most of the hidden materials in the imagery. For MACE we observe a strong dependence on the choice of the material subspace dimension. Increasing this value can lead to a decline in performance.

Snowpack modeling in the context of radiance assimilation for snow water equivalent mapping

Science.gov (United States)

Durand, M. T.; Kim, R. S.; Li, D.; Dumont, M.; Margulis, S. A.

2017-12-01

Data assimilation is often touted as a means of overcoming deficiences in both snowpack modeling and snowpack remote sensing. Direct assimilation of microwave radiances, rather than assimilating microwave retrievals, has shown promise, in this context. This is especially the case for deep mountain snow, which is often assumed to be infeasible to measure with microwave measurements, due to saturation issues. We first demonstrate that the typical way of understanding saturation has often been misunderstood. We show that deep snow leads to a complex microwave signature, but not to saturation per se, because of snowpack stratigraphy. This explains why radiance assimilation requires detailed snowpack models that adequatley stratgigraphy to function accurately. We examine this with two case studies. First, we show how the CROCUS predictions of snowpack stratigraphy allows for assimilation of airborne passive microwave measurements over three 1km2 CLPX Intensive Study Areas. Snowpack modeling and particle filter analysis is performed at 120 m spatial resolution. When run without the benefit of radiance assimilation, CROCUS does not fully capture spatial patterns in the data (R2=0.44; RMSE=26 cm). Assimlilation of microwave radiances for a single flight recovers the spatial pattern of snow depth (R2=0.85; RMSE = 13 cm). This is despite the presence of deep snow; measured depths range from 150 to 325 cm. Adequate results are obtained even for partial forest cover, and bias in precipitation forcing. The results are severely degraded if a three-layer snow model is used, however. The importance of modeling snowpack stratigraphy is highlighted. Second, we compare this study to a recent analysis assimilating spaceborne radiances for a 511 km2 sub-watershed of the Kern River, in the Sierra Nevada. Here, the daily Level 2A AMSR-E footprints (88 km2) are assimilated into a model running at 90 m spatial resolution. The three-layer model is specially adapted to predict "effective

Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

Science.gov (United States)

Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

2017-03-01

As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

Rocket-borne measurements of atmospheric infrared emissions by spectrometric techniques

Science.gov (United States)

Brueckelmann, H. G.; Grossmann, K. U.; Offermann, D.

As part of the MAP/WINE Campaign 1983/84 a liquid-He-cooled IR grating spectrometer measured night zenith radiances of CO2, O3, and H2O in the mesosphere and lower thermosphere. From a comparison of the measured spectral radiances with results from LTE radiative-transfer calculations, atmospheric temperatures and concentration profiles of H2O and O3 were determined, showing some interesting features. The O3 densities appear to contradict model predictions based upon the assumption that O3 is in photochemical equilibrium at mesospheric heights. Since the O3 density distribution shows structures quite similar to the vertical wind profile, transport effects seem to play a major role in the mesospheric O3 formation.

Sky-Radiance Models for Monte Carlo Radiative Transfer Applications

Science.gov (United States)

Santos, I.; Dalimonte, D.; Santos, J. P.

2012-04-01

Photon-tracing can be initialized through sky-radiance (Lsky) distribution models when executing Monte Carlo simulations for ocean color studies. To be effective, the Lsky model should: 1) properly represent sky-radiance features of interest; 2) require low computing time; and 3) depend on a limited number of input parameters. The present study verifies the satisfiability of these prerequisite by comparing results from different Lsky formulations. Specifically, two Lsky models were considered as reference cases because of their different approach among solutions presented in the literature. The first model, developed by the Harrisson and Coombes (HC), is based on a parametric expression where the sun geometry is the unique input. The HC model is one of the sky-radiance analytical distribution applied in state-of-art simulations for ocean optics. The coefficients of the HC model were set upon broad-band field measurements and the result is a model that requires a few implementation steps. The second model, implemented by Zibordi and Voss (ZV), is based on physical expressions that accounts for the optical thickness of permanent gases, aerosol, ozone and water vapour at specific wavelengths. Inter-comparisons between normalized ^LskyZV and ^LskyHC (i.e., with unitary scalar irradiance) are discussed by means of individual polar maps and percent difference between sky-radiance distributions. Sky-radiance cross-sections are presented as well. Considered cases include different sun zenith values and wavelengths (i.e., λ=413, 490 and 665 nm, corresponding to selected center-bands of the MEdium Resolution Imaging Spectrometer MERIS). Results have shown a significant convergence between ^LskyHC and ^LskyZV at 665 nm. Differences between models increase with the sun zenith and mostly with wavelength. For Instance, relative differences up to 50% between ^ L skyHC and ^ LskyZV can be observed in the antisolar region for λ=665 nm and θ*=45°. The effects of these

MicrOmega IR: a new infrared hyperspectral imaging microscope or in situ analysis

Science.gov (United States)

Vaitua, Leroi; Bibring, Jean-Pierre; Berthé, Michel

2017-11-01

MicrOmega IR is an ultra miniaturized Near Infrared hyperspectral microscope for in situ analysis of samples. It is designed to be implemented on board space planetary vehicles (lander and/or rovers). It acquires images of samples typically some 5 mm in width with a spatial sampling of 20 μm. On each pixel, MicrOmega acquires the spectrum in the spectral range 0.9 - 2.6 μm, with a possibility to extend the sensibility up to 4 μm. The spectrum will be measured in up to 300 contiguous spectral channels (600 in the extended range): given the diagnostic spectral features present in this domain, it provides the composition of each spatially resolved constituent. MicrOmega has thus the potential to identify: minerals, such as pyroxene and olivine, ferric oxides, hydrated phases such as phyllosilicates, sulfates and carbonates, ices and organics. The composition of the various phases within a given sample is a critical record of its formation and evolution. Coupled to the mapping information, it provides unique clues to describe the history of the parent body. In particular, the capability to identify hydrated grains and to characterize their adjacent phases has a huge potential in the search for potential bio-relics in Martian samples. This purely non destructive characterization enables further analyses (e.g. through mass spectrometry) to be performed, and/or to contribute to sample selection to return to Earth. MicrOmega IR is coupled to a visible microscope: MicrOmega VIS. Thus, the MicrOmega instrument is developed by an international consortium: IAS (Orsay, France), LESIA (Meudon, France), CBM (Orléans, France), University Of Bern (Bern, Switzerland), IKI (Moscow, Russia). This instrument (MicrOmega IR, MicrOmega VIS and the electronics) is selected for the ESA Exomars mission (launch scheduled for 2013). MicrOmega IR will be used in a reduced spectral range (0.9 - 2.6 μm), due to power, mass and thermal constraints: however, most minerals and other

Very High Spectral Resolution Imaging Spectroscopy: the Fluorescence Explorer (FLEX) Mission

Science.gov (United States)

Moreno, Jose F.; Goulas, Yves; Huth, Andreas; Middleton, Elizabeth; Miglietta, Franco; Mohammed, Gina; Nedbal, Ladislav; Rascher, Uwe; Verhoef, Wouter; Drusch, Matthias

2016-01-01

The Fluorescence Explorer (FLEX) mission has been recently selected as the 8th Earth Explorer by the European Space Agency (ESA). It will be the first mission specifically designed to measure from space vegetation fluorescence emission, by making use of very high spectral resolution imaging spectroscopy techniques. Vegetation fluorescence is the best proxy to actual vegetation photosynthesis which can be measurable from space, allowing an improved quantification of vegetation carbon assimilation and vegetation stress conditions, thus having key relevance for global mapping of ecosystems dynamics and aspects related with agricultural production and food security. The FLEX mission carries the FLORIS spectrometer, with a spectral resolution in the range of 0.3 nm, and is designed to fly in tandem with Copernicus Sentinel-3, in order to provide all the necessary spectral / angular information to disentangle emitted fluorescence from reflected radiance, and to allow proper interpretation of the observed fluorescence spatial and temporal dynamics.

Radiance intensity enhanced by thin inhomogeneous lossy films

International Nuclear Information System (INIS)

Ben-Abdallah, Philippe; Ni Bo

2004-01-01

Basically, the classical radiative transfer theory assumes that the coherent component of the radiation field is equal to zero and heuristic considerations about energy conservation are used in the phenomenological derivation of the RTE. Here a self-consistent theory is presented to investigate radiative transport in the presence of diffraction processes within thin inhomogeneous films. The problem of linear optics about the transport of scalar radiation within film is solved, a new definition of the radiance is introduced in agreement with earlier definitions and a corresponding radiative transfer equation is derived. The influence of spatial variations of the bulk properties on the propagating mode is described in detail. It is analytically predicted that, unlike homogeneous media, an inhomogeneous film can enhance the radiance intensity in spite of the diffraction and the local extinction. From a practical point of view, the results of this work should be useful to perform the optimal design for many thermoelectric devices such as the new generations of photovoltaiec cells

Analytical properties of the radiance in atmospheric radiative transfer theory

International Nuclear Information System (INIS)

Otto, Sebastian

2014-01-01

It is demonstrated mathematically strictly that state density functions, as the radiance (specific intensity), exist to describe certain state properties of transported photons on microscopic and the state of the radiation field on macroscopic scale, which have independent physical meanings. Analytical properties as boundedness, continuity, differentiability and integrability of these functions to describe the photon transport are discussed. It is shown that the density functions may be derived based on the assumption of photons as real particles of non-zero and finite size, independently of usual electrodynamics, and certain historically postulated functional relationships between them were proved, that is, these functions can be derived mathematically strictly and consistently within the framework of the theory of the phenomenological radiative transfer if one takes the theory seriously by really assuming photons as particles. In this sense these functions may be treated as fundamental physical quantities within the scope of this theory, if one considers the possibility of the existence of photons. -- Highlights: • Proof of existence of the radiance within the scope of the theory of atmospheric radiative transfer. • Proof of relations between the photon number and photon energy density function and the radiance. • Strictly mathematical derivation of the analytical properties of these state density functions

Airborne pipeline leak detection: UV or IR?

Science.gov (United States)

Babin, François; Gravel, Jean-François; Allard, Martin

2016-05-01

This paper presents a study of different approaches to the measurement of the above ground vapor plume created by the spill caused by a small 0.1 l/min (or less) leak in an underground liquid petroleum pipeline. The scenarios are those for the measurement from an airborne platform. The usual approach is that of IR absorption, but in the case of liquid petroleum products, there are drawbacks that will be discussed, especially when using alkanes to detect a leak. The optical measurements studied include UV enhanced Raman lidar, UV fluorescence lidar and IR absorption path integrated lidars. The breadboards used for testing the different approaches will be described along with the set-ups for leak simulation. Although IR absorption would intuitively be the most sensitive, it is shown that UV-Raman could be an alternative. When using the very broad alkane signature in the IR, the varying ground spectral reflectance are a problem. It is also determined that integrated path measurements are preferred, the UV enhanced Raman measurements showing that the vapor plume stays very close to the ground.

Infrared spectral imaging as a novel approach for histopathological recognition in colon cancer diagnosis

Science.gov (United States)

Nallala, Jayakrupakar; Gobinet, Cyril; Diebold, Marie-Danièle; Untereiner, Valérie; Bouché, Olivier; Manfait, Michel; Sockalingum, Ganesh Dhruvananda; Piot, Olivier

2012-11-01

Innovative diagnostic methods are the need of the hour that could complement conventional histopathology for cancer diagnosis. In this perspective, we propose a new concept based on spectral histopathology, using IR spectral micro-imaging, directly applied to paraffinized colon tissue array stabilized in an agarose matrix without any chemical pre-treatment. In order to correct spectral interferences from paraffin and agarose, a mathematical procedure is implemented. The corrected spectral images are then processed by a multivariate clustering method to automatically recover, on the basis of their intrinsic molecular composition, the main histological classes of the normal and the tumoral colon tissue. The spectral signatures from different histological classes of the colonic tissues are analyzed using statistical methods (Kruskal-Wallis test and principal component analysis) to identify the most discriminant IR features. These features allow characterizing some of the biomolecular alterations associated with malignancy. Thus, via a single analysis, in a label-free and nondestructive manner, main changes associated with nucleotide, carbohydrates, and collagen features can be identified simultaneously between the compared normal and the cancerous tissues. The present study demonstrates the potential of IR spectral imaging as a complementary modern tool, to conventional histopathology, for an objective cancer diagnosis directly from paraffin-embedded tissue arrays.

Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions

International Nuclear Information System (INIS)

Grant, R.H.; Heisler, G.M.; Gao, W.

1996-01-01

The photosynthetically active radiation (PAR), defined as the wavelength band of 0.400 μm to 0.700 μm, represents most of the visible solar radiation. Although the proportion of global irradiance that originates from diffuse sky radiation is higher for PAR than for all solar shortwave radiation, it is often assumed that the PAR diffuse sky radiation is distributed identically to that of all shortwave solar radiation. This assumption has not been tested. PAR sky radiance measurements were made in a rural area over a wide range of solar zenith angles. The distribution of PAR sky radiance was modeled using physically-based, non-linear equations.For clear skies, the normalized sky radiance distribution (N) was best modeled using the scattering angle (ψ) and the zenith position in the sky (Θ) as N (Θ, ψ) = 0.0361 [6.3 + (1 + cos 2 Θ / (1 - cos ψ)] [1-e -0.31 sec ( Θ]. The angle Ψ is defined by cos ψ = cos Θ cos Θ * + sin Θ sin Θ * cos Φ, where solar zenith angle is Θ* and the difference in azimuth between the sun and the position in the sky is Φ. Modeling of the overcast sky depended on the visibility of the solar disk. The translucent middle/high cloud overcast conditions (cloud base greater than 300 m above ground level) were best modeled as: N(Θ∗, ψ) = 0.149 + 0.084Θ∗ + 1.305e −2.5ψ while the translucent low cloud overcast conditions (cloud base less than 300 m above ground level) were best modeled as: N(Θ∗, ψ) = 0.080 + 0.058Θ∗ + 0.652e −2.1ψ . The obscured overcast sky condition (solar disk obscured) was best modeled as: N(Θ) = 0.441 [1 + 4.6cos Θ] /[1 + 4.6]. The unit of N for all equations is π Sr −1 , so that integration of each function over the sky hemisphere yields 1.0.These equations can be applied directly to the sky diffuse irradiance on the horizontal, I diff , to provide radiance distributions for the sky. Estimates of actual sky radiance distribution can be estimated from N a (Θ, ψ) = I diff N(Θ, �

Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

Science.gov (United States)

Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

2017-03-05

As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR. Copyright © 2016 Elsevier B.V. All rights reserved.

Low loss mid-IR transmission bands using silica hollow-core anisotropic anti-resonant fibers

DEFF Research Database (Denmark)

Habib, Selim; Bang, Ole; Bache, Morten

2016-01-01

In this paper, a node-free anisotropic hollow-core anti-resonant fiber has been proposed to give low transmission loss in the near-IR to mid-IR spectral regime. The proposed silica-based fiber design shows transmission loss below 10 dB/km at 2.94 μm with multiple low loss transmission bands. Tran...

Observation of Tidal Effects on LWIR Radiance Above the Mesopause

National Research Council Canada - National Science Library

Wintersteiner, Peter

2007-01-01

An examination of CO2 infrared limb radiance, directly measured by the SABER instrument aboard the TIMED satellite, reveals unusual structure in the region just above the mesopause, at tangent heights...

THE ROLE OF THE ACCRETION DISK, DUST, AND JETS IN THE IR EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Mason, R. E. [Gemini Observatory, Northern Operations Center, 670 N. A' ohoku Place, Hilo, HI 96720 (United States); Ramos Almeida, C. [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain); Levenson, N. A. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Nemmen, R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Alonso-Herrero, A., E-mail: rmason@gemini.edu [Instituto de Física de Cantabria, CSIC-UC, Avenida de los Castros s/n, E-39005 Santander (Spain)

2013-11-10

We use recent high-resolution infrared (IR; 1-20 μm) photometry to examine the origin of the IR emission in low-luminosity active galactic nuclei (LLAGN). The data are compared with published model fits that describe the spectral energy distribution (SED) of LLAGN in terms of an advection-dominated accretion flow, truncated thin accretion disk, and jet. The truncated disk in these models is usually not luminous enough to explain the observed IR emission, and in all cases its spectral shape is much narrower than the broad IR peaks in the data. Synchrotron radiation from the jet appears to be important in very radio-loud nuclei, but the detection of strong silicate emission features in many objects indicates that dust must also contribute. We investigate this point by fitting the IR SED of NGC 3998 using dusty torus and optically thin (τ{sub mid-IR} ∼ 1) dust shell models. While more detailed modeling is necessary, these initial results suggest that dust may account for the nuclear mid-IR emission of many LLAGN.

Raman and Mid-IR Spectral Analysis of the Atacamite-Structure Hydroxyl/Deuteroxyl Nickel Chlorides Ni2(OH/D)3Cl

Institute of Scientific and Technical Information of China (English)

LIU Xiao-Dong; Hagihala Masato; ZHENG Xu-Guang; MENG Dong-Doug; GUO Qi-Xin

2011-01-01

@@ Vibrational spectra(Raman 4000-95cm-1 and mid-IR 4000-400cm-1) of the atacamite-structure Ni2(OH)3Cl,including a rarely reported kind of asymmetric trimetric hydrogen bond, as a member of the geometrically frustrated material series and its deuteride Ni2(OD)3Cl are, to the best of our knowledge, reported for the first time and analyzed at room temperature.Through a comparative study of four spectra according to their crystal structural parameters, we assign OH stretching modes v(OH) in a functional group region(3700-3400 cm-1) and their deformation modes δ(NiOH/D) in the correlation peak region(900-600 cm-1)with the corresponding mode frequency ratios ωv(OD)/ωv(OH)≈73% and ωδ(NiOD)/ωδ(NiOH)≈75%, and further self-consistently suggest NiO and Ni-Cl related modes in the fingerprint region(500-200cm-1 and 200-Ocm-1, respectively) by use of the unified six-ligand NiO5Cl and NiO4Cl2 frames.This report may contribute to the spectral analysis of other hydroxyl transition-metal halides and to the understanding of the fundamental physics of their exotic magnetic geometrical frustration property from the spectral changes around the corresponding low transition temperatures.

ASTER L2 Surface Radiance VNIR and SWIR V003

Data.gov (United States)

National Aeronautics and Space Administration — The ASTER L2 Surface Radiance is a multi-file product that contains atmospherically corrected data for both the Visible Near-Infrared (VNIR) and Shortwave Infrared...

2.5 TW, two-cycle IR laser pulses via frequency domain optical parametric amplification.

Science.gov (United States)

Gruson, V; Ernotte, G; Lassonde, P; Laramée, A; Bionta, M R; Chaker, M; Di Mauro, L; Corkum, P B; Ibrahim, H; Schmidt, B E; Legaré, F

2017-10-30

Broadband optical parametric amplification in the IR region has reached a new milestone through the use of a non-collinear Frequency domain Optical Parametric Amplification system. We report a laser source delivering 11.6 fs pulses with 30 mJ of energy at a central wavelength of 1.8 μm at 10 Hz repetition rate corresponding to a peak power of 2.5 TW. The peak power scaling is accompanied by a pulse shortening of about 20% upon amplification due to the spectral reshaping with higher gain in the spectral wings. This source paves the way for high flux soft X-ray pulses and IR-driven laser wakefield acceleration.

Oxadiazole-carbazole polymer (POC)-Ir(ppy)3 tunable emitting composites

Science.gov (United States)

Bruno, Annalisa; Borriello, Carmela; Di Luccio, Tiziana; Sessa, Lucia; Concilio, Simona; Haque, Saif A.; Minarini, Carla

2017-04-01

POC polymer is an oxadiazole-carbazole copolymer we have previously synthetized and established as light emitting material in Organic Light Emitting Devices (OLEDs), although POC quantum yield emission efficiency and color purity still need to be enhanced. On the other hand, tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) complexes, namely Ir(ppy)3 are among the brightest luminophores employed in green light emitting devices. Our aim, in this work, is to take advantage of Ir(ppy)3 bright emission by combining the Ir complex with blue emitting POC to obtain tunable light emitting composites over a wide range of the visible spectrum. Here we have investigated the optical proprieties POC based nanocomposites with different concentrations of Ir(ppy)3, ranging from 1 to 10 wt%. Both spectral and time resolved fluorescence measurements show an efficient energy transfer from the polymer to the dopants, resulting in white-emitting composites. The most intense and stable emission has been found when POC was doped with about 5 wt% concentration of Ir(ppy)3.

Estimating top-of-atmosphere thermal infrared radiance using MERRA-2 atmospheric data

Science.gov (United States)

Kleynhans, Tania; Montanaro, Matthew; Gerace, Aaron; Kanan, Christopher

2017-05-01

Thermal infrared satellite images have been widely used in environmental studies. However, satellites have limited temporal resolution, e.g., 16 day Landsat or 1 to 2 day Terra MODIS. This paper investigates the use of the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data product, produced by NASA's Global Modeling and Assimilation Office (GMAO) to predict global topof-atmosphere (TOA) thermal infrared radiance. The high temporal resolution of the MERRA-2 data product presents opportunities for novel research and applications. Various methods were applied to estimate TOA radiance from MERRA-2 variables namely (1) a parameterized physics based method, (2) Linear regression models and (3) non-linear Support Vector Regression. Model prediction accuracy was evaluated using temporally and spatially coincident Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared data as reference data. This research found that Support Vector Regression with a radial basis function kernel produced the lowest error rates. Sources of errors are discussed and defined. Further research is currently being conducted to train deep learning models to predict TOA thermal radiance

A System for Compressive Spectral and Polarization Imaging at Short Wave Infrared (SWIR) Wavelengths

Science.gov (United States)

2017-10-18

UV -­‐ VIS -­‐IR   60mm   Apo   Macro  lens   Jenoptik-­‐Inc   $5,817.36   IR... VIS /NIR Compressive Spectral Imager”, Proceedings of IEEE International Conference on Image Processing (ICIP ’15), Quebec City, Canada, (September...imaging   system   will   lead   to   a   wide-­‐band   VIS -­‐NIR-­‐SWIR   compressive  spectral  and  polarimetric

Estimation of Soil Moisture Content from the Spectral Reflectance of Bare Soils in the 0.4–2.5 µm Domain

Directory of Open Access Journals (Sweden)

Sophie Fabre

2015-02-01

Full Text Available This work aims to compare the performance of new methods to estimate the Soil Moisture Content (SMC of bare soils from their spectral signatures in the reflective domain (0.4–2.5 µm in comparison with widely used spectral indices like Normalized Soil Moisture Index (NSMI and Water Index SOIL (WISOIL. Indeed, these reference spectral indices use wavelengths located in the water vapour absorption bands and their performance are thus very sensitive to the quality of the atmospheric compensation. To reduce these limitations, two new spectral indices are proposed which wavelengths are defined using the determination matrix tool by taking into account the atmospheric transmission: Normalized Index of Nswir domain for Smc estimatiOn from Linear correlation (NINSOL and Normalized Index of Nswir domain for Smc estimatiOn from Non linear correlation (NINSON. These spectral indices are completed by two new methods based on the global shape of the soil spectral signatures. These methods are the Inverse Soil semi-Empirical Reflectance model (ISER, using the inversion of an existing empirical soil model simulating the soil spectral reflectance according to soil moisture content for a given soil class, and the convex envelope model, linking the area between the envelope and the spectral signature to the SMC. All these methods are compared using a reference database built with 32 soil samples and composed of 190 spectral signatures with five or six soil moisture contents. Half of the database is used for the calibration stage and the remaining to evaluate the performance of the SMC estimation methods. The results show that the four new methods lead to similar or better performance than the one obtained by the reference indices. The RMSE is ranging from 3.8% to 6.2% and the coefficient of determination R2 varies between 0.74 and 0.91 with the best performance obtained with the ISER model. In a second step, simulated spectral radiances at the sensor level are

Multiwaveband simulation-based signature analysis of camouflaged human dismounts in cluttered environments with TAIThermIR and MuSES

Science.gov (United States)

Packard, Corey D.; Klein, Mark D.; Viola, Timothy S.; Hepokoski, Mark A.

2016-10-01

The ability to predict electro-optical (EO) signatures of diverse targets against cluttered backgrounds is paramount for signature evaluation and/or management. Knowledge of target and background signatures is essential for a variety of defense-related applications. While there is no substitute for measured target and background signatures to determine contrast and detection probability, the capability to simulate any mission scenario with desired environmental conditions is a tremendous asset for defense agencies. In this paper, a systematic process for the thermal and visible-through-infrared simulation of camouflaged human dismounts in cluttered outdoor environments is presented. This process, utilizing the thermal and EO/IR radiance simulation tool TAIThermIR (and MuSES), provides a repeatable and accurate approach for analyzing contrast, signature and detectability of humans in multiple wavebands. The engineering workflow required to combine natural weather boundary conditions and the human thermoregulatory module developed by ThermoAnalytics is summarized. The procedure includes human geometry creation, human segmental physiology description and transient physical temperature prediction using environmental boundary conditions and active thermoregulation. Radiance renderings, which use Sandford-Robertson BRDF optical surface property descriptions and are coupled with MODTRAN for the calculation of atmospheric effects, are demonstrated. Sensor effects such as optical blurring and photon noise can be optionally included, increasing the accuracy of detection probability outputs that accompany each rendering. This virtual evaluation procedure has been extensively validated and provides a flexible evaluation process that minimizes the difficulties inherent in human-subject field testing. Defense applications such as detection probability assessment, camouflage pattern evaluation, conspicuity tests and automatic target recognition are discussed.

Observation of Tidal Effects on LWIR Radiance Above the Mesopause

National Research Council Canada - National Science Library

Wintersteiner, Peter

2007-01-01

..., and season The local-time dependence, in particular, suggests a role for atmospheric tides using a tidal model, Global Scale Wave Model, and our non-GTE ARC rode, we modeled the 15 Om radiance...

Observation of Tidal Effects on LWIR Radiance Above the Mesopause

National Research Council Canada - National Science Library

Wintersteiner, Peter

2007-01-01

An examination of CO2 infrared limb radiance, directly measured by the SABER instrument aboard the TIMED satellite, reveals unusual structure in the region just above the mesopause, at tangent heights of -95-110 km...

Spectral Identification of New Galactic cLBV and WR Stars

Science.gov (United States)

Stringfellow, G. S.; Gvaramadze, V. V.; Beletsky, Y.; Kniazev, A. Y.

2012-12-01

We have undertaken a near-IR spectral survey of stars associated with compact nebulae recently revealed by the Spitzer and WISE imaging surveys. These circumstellar nebulae, produced by massive evolved stars, display a variety of symmetries and shapes and are often only evident at mid-IR wavelengths. Stars associated with ˜50 of these nebulae have been observed. We also obtained recent spectra of previously confirmed (known) luminous blue variables (LBVs) and candidate LBVs (cLBVs). The spectral similarity of the stars observed when compared directly to known LBVs and Wolf-Rayet (WR) stars indicate many are newly identified cLBVs, with a few being newly discovered WR stars, mostly of WN8-9h spectral type. These results suggest that a large population of previously unidentified cLBVs and related transitional stars reside in the Galaxy and confirm that circumstellar nebulae are inherent to most (c)LBVs.

Radiometric modeling and calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) ground based measurement experiment

Science.gov (United States)

Tian, Jialin; Smith, William L.; Gazarik, Michael J.

2008-12-01

The ultimate remote sensing benefits of the high resolution Infrared radiance spectrometers will be realized with their geostationary satellite implementation in the form of imaging spectrometers. This will enable dynamic features of the atmosphere's thermodynamic fields and pollutant and greenhouse gas constituents to be observed for revolutionary improvements in weather forecasts and more accurate air quality and climate predictions. As an important step toward realizing this application objective, the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) Engineering Demonstration Unit (EDU) was successfully developed under the NASA New Millennium Program, 2000-2006. The GIFTS-EDU instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The GIFTS calibration is achieved using internal blackbody calibration references at ambient (260 K) and hot (286 K) temperatures. In this paper, we introduce a refined calibration technique that utilizes Principle Component (PC) analysis to compensate for instrument distortions and artifacts, therefore, enhancing the absolute calibration accuracy. This method is applied to data collected during the GIFTS Ground Based Measurement (GBM) experiment, together with simultaneous observations by the accurately calibrated AERI (Atmospheric Emitted Radiance Interferometer), both simultaneously zenith viewing the sky through the same external scene mirror at ten-minute intervals throughout a cloudless day at Logan Utah on September 13, 2006. The accurately calibrated GIFTS radiances are produced using the first four PC scores in the GIFTS-AERI regression model. Temperature and moisture profiles retrieved from the PC-calibrated GIFTS radiances are verified against radiosonde measurements collected throughout the GIFTS sky measurement period. Using the GIFTS GBM calibration model, we compute the calibrated radiances from data

Predicting top-of-atmosphere radiance for arbitrary viewing geometries from the visible to thermal infrared: generalization to arbitrary average scene temperatures

Science.gov (United States)

Florio, Christopher J.; Cota, Steve A.; Gaffney, Stephanie K.

2010-08-01

In a companion paper presented at this conference we described how The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) may be used in conjunction with a limited number of runs of AFRL's MODTRAN4 radiative transfer code, to quickly predict the top-of-atmosphere (TOA) radiance received in the visible through midwave IR (MWIR) by an earth viewing sensor, for any arbitrary combination of solar and sensor elevation angles. The method is particularly useful for large-scale scene simulations where each pixel could have a unique value of reflectance/emissivity and temperature, making the run-time required for direct prediction via MODTRAN4 prohibitive. In order to be self-consistent, the method described requires an atmospheric model (defined, at a minimum, as a set of vertical temperature, pressure and water vapor profiles) that is consistent with the average scene temperature. MODTRAN4 provides only six model atmospheres, ranging from sub-arctic winter to tropical conditions - too few to cover with sufficient temperature resolution the full range of average scene temperatures that might be of interest. Model atmospheres consistent with intermediate temperature values can be difficult to come by, and in any event, their use would be too cumbersome for use in trade studies involving a large number of average scene temperatures. In this paper we describe and assess a method for predicting TOA radiance for any arbitrary average scene temperature, starting from only a limited number of model atmospheres.

Salinity and spectral reflectance of soils

Science.gov (United States)

Szilagyi, A.; Baumgardner, M. F.

1991-01-01

The basic spectral response related to the salt content of soils in the visible and reflective IR wavelengths is analyzed in order to explore remote sensing applications for monitoring processes of the earth system. The bidirectional reflectance factor (BRF) was determined at 10 nm of increments over the 520-2320-nm spectral range. The effect of salts on reflectance was analyzed on the basis of 162 spectral measurements. MSS and TM bands were simulated within the measured spectral region. A strong relationship was found in variations of reflectance and soil characteristics pertaining to salinization and desalinization. Although the individual MSS bands had high R-squared values and 75-79 percent of soil/treatment combinations were separable, there was a large number of soil/treatment combinations not distinguished by any of the four highly correlated MSS bands under consideration.

Clinical effects of an oral supplement rich in antioxidants on skin radiance in women

Directory of Open Access Journals (Sweden)

Dumoulin M

2016-10-01

Full Text Available Marion Dumoulin, David Gaudout, Benoit Lemaire Activ’Inside, Libourne, France Background: Environmental factors impact the skin aging resulting in decrease of skin radiance. Nutrition and particularly antioxidants could help to fight against skin degradation.Objective: The aim of this study was to evaluate the effects of an oral supplement rich in specific antioxidants, SkinAx2TM, on the improvement of the skin radiance in women.Methods: The open-label clinical study enrolled 35 women, aged 40–70, with facial dull complexion. Subjects were supplemented orally with a daily dosage of 150 mg of an antioxidant-rich formulation containing superoxide dismutase-rich melon concentrate, grape seed extract rich in monomers of flavanols, vitamin C, and zinc for 8 weeks. Each subject served as her own control. The C.L.B.T.™ test has been used to evaluate facial skin coloring (C, luminosity (L, brightness (B, and transparency (T involved in skin radiance. Facial skin imperfections have been assessed by clinical assessment. Firmness has been evaluated by clinical assessment and cutometer measurement. Finally, an auto-questionnaire has been carried out in order to evaluate the satisfaction of the subjects concerning different parameters involved in skin radiance and the global efficacy of the supplement.Results: Skin “red pink” and “olive” colors were significantly improved after supplementation (P<0.0001. Luminosity was increased by 25.9% (P<0.0001 whereas brightness and transparency were not affected by the supplementation. Facial skin imperfections were significantly reduced after the antioxidant-rich formulation intake (global reduction: –18.0%; P<0.0001. Indeed, dark circles, redness, and spots significantly diminished after oral treatment. Firmness and elasticity have been shown to be improved. Subjects were globally satisfied by the product (82.4% and have found improvements on their facial skin. Furthermore, 64.7% reported to look

Multichannel Dynamic Fourier-Transform IR Spectrometer

Science.gov (United States)

Balashov, A. A.; Vaguine, V. A.; Golyak, Il. S.; Morozov, A. N.; Khorokhorin, A. I.

2017-09-01

A design of a multichannel continuous scan Fourier-transform IR spectrometer for simultaneous recording and analysis of the spectral characteristics of several objects is proposed. For implementing the design, a multi-probe fiber is used, constructed from several optical fibers connected into a single optical connector and attached at the output of the interferometer. The Fourier-transform spectrometer is used as a signal modulator. Each fiber is individually mated with an investigated sample and a dedicated radiation detector. For the developed system, the radiation intensity of the spectrometer is calculated from the condition of the minimum spectral resolution and parameters of the optical fibers. Using the proposed design, emission spectra of a gas-discharge neon lamp have been recorded using a single fiber 1 mm in diameter with a numerical aperture NA = 0.22.

Simulation of at-sensor radiance over land for proposed thermal ...

Indian Academy of Sciences (India)

Satellite level at-sensor radiance corresponding to all four infrared channels of. INSAT-3D Imager payload is .... its heritage traces back to LOWTRAN. MOD-. TRAN includes all ... over tropical region (SeeBor dataset) are car- ried out with the ...

Normalization and calibration of geostationary satellite radiances for the International Satellite Cloud Climatology Project

Science.gov (United States)

Desormeaux, Yves; Rossow, William B.; Brest, Christopher L.; Campbell, G. G.

1993-01-01

Procedures are described for normalizing the radiometric calibration of image radiances obtained from geostationary weather satellites that contributed data to the International Satellite Cloud Climatology Project. The key step is comparison of coincident and collocated measurements made by each satellite and the concurrent AVHRR on the 'afternoon' NOAA polar-orbiting weather satellite at the same viewing geometry. The results of this comparison allow transfer of the AVHRR absolute calibration, which has been established over the whole series, to the radiometers on the geostationary satellites. Results are given for Meteosat-2, 3, and 4, for GOES-5, 6, and 7, for GMS-2, 3, and 4 and for Insat-1B. The relative stability of the calibrations of these radiance data is estimated to be within +/- 3 percent; the uncertainty of the absolute calibrations is estimated to be less than 10 percent. The remaining uncertainties are at least two times smaller than for the original radiance data.

Pixelated coatings and advanced IR coatings

Science.gov (United States)

Pradal, Fabien; Portier, Benjamin; Oussalah, Meihdi; Leplan, Hervé

2017-09-01

Reosc developed pixelated infrared coatings on detector. Reosc manufactured thick pixelated multilayer stacks on IR-focal plane arrays for bi-spectral imaging systems, demonstrating high filter performance, low crosstalk, and no deterioration of the device sensitivities. More recently, a 5-pixel filter matrix was designed and fabricated. Recent developments in pixelated coatings, shows that high performance infrared filters can be coated directly on detector for multispectral imaging. Next generation space instrument can benefit from this technology to reduce their weight and consumptions.

Radiance Research Particle Soot/Absorption Photometer Instrument Handbook

Energy Technology Data Exchange (ETDEWEB)

Springston, S. R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2016-03-01

Radiance Research PSAPs as described in this Handbook are deployed in the second ARM Mobile Facility (AMF2) Aerosol Observing System (AOS), the third ARM Mobile Facility (AMF3) AOS, ENA AOS and Mobile Aerosol Observing System (MAOS)-A. An earlier version of the PSAP is currently operated in the ARM Aerial Facility and at SGP. The older SGP instrument is covered in a separate Handbook.

Multi-sensor Cloud Retrieval Simulator and Remote Sensing from Model Parameters . Pt. 1; Synthetic Sensor Radiance Formulation; [Synthetic Sensor Radiance Formulation

Science.gov (United States)

Wind, G.; DaSilva, A. M.; Norris, P. M.; Platnick, S.

2013-01-01

In this paper we describe a general procedure for calculating synthetic sensor radiances from variable output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint, the algorithm takes explicit account of the model subgrid variability, in particular its description of the probability density function of total water (vapor and cloud condensate.) The simulated sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies.We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products). We focus on clouds because they are very important to model development and improvement.

NUCAPS: NOAA Unique Combined Atmospheric Processing System Cloud-Cleared Radiances (CCR)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of Cloud-Cleared Radiances (CCRs) from the NOAA Unique Combined Atmospheric Processing System (NUCAPS). NUCAPS was developed by the NOAA/NESDIS...

Multiseasonal-multispectral remote sensing of phenological change for natural vegetation inventory. Ph.D. Thesis

Science.gov (United States)

Schrumpf, B. J. (Principal Investigator)

1975-01-01

The author has identified the following significant results. Variations in phenological development among plant species was noted, as well as the tendency for the seasonal appearance of some vegetation types to be dominated by the appearance of one or a few similarly developing species. Most of the common plants in the study area could be characterized by temporal aspects of their phenological development. There was a strong similarity among the spectral signatures of vegetation types in which the spectral return was dominated by green plant material. When the soil background dominated the spectral return from a vegetation stand, then the spectral radiance and the vegetation physiognomy were apparently related. When the deciduous shrubs lost their leaves, their spectral signature altered with a slight decrease of radiance in the visible wavelengths and a strong decrease in the near infrared. As the foliage of perennial grasses cured from August to November, its apparent green radiance remained unchanged, red radiance increased over 50 percent, and near infrared radiance decreased approximately 30 percent. A reflective mineral surface exhibited high radiance levels in all four bands, thus providing a marked contrast to the absorption characteristics of vegetation canopies.

Examining Dense Data Usage near the Regions with Severe Storms in All-Sky Microwave Radiance Data Assimilation and Impacts on GEOS Hurricane Analyses

Science.gov (United States)

Kim, Min-Jeong; Jin, Jianjun; McCarty, Will; El Akkraoui, Amal; Todling, Ricardo; Gelaro, Ron

2018-01-01

Many numerical weather prediction (NWP) centers assimilate radiances affected by clouds and precipitation from microwave sensors, with the expectation that these data can provide critical constraints on meteorological parameters in dynamically sensitive regions to make significant impacts on forecast accuracy for precipitation. The Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center assimilates all-sky microwave radiance data from various microwave sensors such as all-sky GPM Microwave Imager (GMI) radiance in the Goddard Earth Observing System (GEOS) atmospheric data assimilation system (ADAS), which includes the GEOS atmospheric model, the Gridpoint Statistical Interpolation (GSI) atmospheric analysis system, and the Goddard Aerosol Assimilation System (GAAS). So far, most of NWP centers apply same large data thinning distances, that are used in clear-sky radiance data to avoid correlated observation errors, to all-sky microwave radiance data. For example, NASA GMAO is applying 145 km thinning distances for most of satellite radiance data including microwave radiance data in which all-sky approach is implemented. Even with these coarse observation data usage in all-sky assimilation approach, noticeable positive impacts from all-sky microwave data on hurricane track forecasts were identified in GEOS-5 system. The motivation of this study is based on the dynamic thinning distance method developed in our all-sky framework to use of denser data in cloudy and precipitating regions due to relatively small spatial correlations of observation errors. To investigate the benefits of all-sky microwave radiance on hurricane forecasts, several hurricane cases selected between 2016-2017 are examined. The dynamic thinning distance method is utilized in our all-sky approach to understand the sources and mechanisms to explain the benefits of all-sky microwave radiance data from various microwave radiance sensors like Advanced Microwave Sounder Unit

Improving the description of sunglint for accurate prediction of remotely sensed radiances

Energy Technology Data Exchange (ETDEWEB)

Ottaviani, Matteo [Light and Life Laboratory, Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 (United States)], E-mail: mottavia@stevens.edu; Spurr, Robert [RT Solutions Inc., 9 Channing Street, Cambridge, MA 02138 (United States); Stamnes, Knut; Li Wei [Light and Life Laboratory, Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 (United States); Su Wenying [Science Systems and Applications Inc., 1 Enterprise Parkway, Hampton, VA 23666 (United States); Wiscombe, Warren [NASA GSFC, Greenbelt, MD 20771 (United States)

2008-09-15

The bidirectional reflection distribution function (BRDF) of the ocean is a critical boundary condition for radiative transfer calculations in the coupled atmosphere-ocean system. Existing models express the extent of the glint-contaminated region and its contribution to the radiance essentially as a function of the wind speed. An accurate treatment of the glint contribution and its propagation in the atmosphere would improve current correction schemes and hence rescue a significant portion of data presently discarded as 'glint contaminated'. In current satellite imagery, a correction to the sensor-measured radiances is limited to the region at the edge of the glint, where the contribution is below a certain threshold. This correction assumes the sunglint radiance to be directly transmitted through the atmosphere. To quantify the error introduced by this approximation we employ a radiative transfer code that allows for a user-specified BRDF at the atmosphere-ocean interface and rigorously accounts for multiple scattering. We show that the errors incurred by ignoring multiple scattering are very significant and typically lie in the range 10-90%. Multiple reflections and shadowing at the surface can also be accounted for, and we illustrate the importance of such processes at grazing geometries.

Retrieving SW fluxes from geostationary narrowband radiances for the NASA-CERES SYN1deg product

Science.gov (United States)

Wrenn, F. J., IV; Doelling, D. R.; Liang, L.

2017-12-01

The CERES mission was designed to measure the natural variability of the net TOA flux over long time scales relevant to climate monitoring. To achieve this goal, CERES provides the level-3 SSF1deg, SYN1deg, and EBAF monthly 1° by 1° regional TOA flux. The single satellite (Terra or Aqua) SSF1deg 24-hour shortwave flux is based on one daytime measurements and assumes constant meteorology to model the diurnal change in albedo. To accurately describe regions with a prominent diurnal signal, the SYN1deg Edition4 dataset employs hourly geostationary (GEO) measurements. This improves upon Edition3, which used 3-hourly GEO measurements and with temporal interpolation. The EBAF product combines the temporal stability of the SSF1deg product with the diurnal information from SYN1deg and removes the CERES instrument calibration bias by constraining the net flux balance to the ocean heat storage term. The SYN-1deg product retrieves hourly SW fluxes from GEO measurements. Over regions with large diurnal cycles, such as maritime stratus and land afternoon convective locations, the GEO derived SW fluxes will capture the diurnal flux not observed with Terra or Aqua sun-synchronous satellites. Obtaining fluxes from geostationary satellite radiance is a multistep process. First, most GEO visible imagers lack calibration and must be calibrated to MODIS and VIIRS. Second, the GEO imager visible channel radiances are converted to broadband radiances using empirical and theoretical models. The lack of coincident, collocated, and co-angled GEO and CERES measurements makes building an empirical model difficult. The narrowband to broadband models are a function of surface and cloud conditions, which are difficult to identify due to the inconsistent cloud retrievals between the 16 GEO imagers used in the CERES record. Third, the GEO derived broadband radiances are passed through the CERES angular distribution model (ADM) to convert the radiances to fluxes. Lastly, the GEO derived

Signal-to-solar clutter calculations of AK-47 muzzle flash at various spectral bandpasses near the potassium D1/D2 doublet

Science.gov (United States)

Klett, Karl K., Jr.

2010-04-01

An analysis was performed, using MODTRAN, to determine the best filters to use for detecting the muzzle flash of an AK-47 in daylight conditions in the desert. Filters with bandwidths of 0.05, 0.1, 0.5, 1.0, 3.0, and 5.0 nanometers (nm) were analyzed to understand how the optical bandwidth affects the signal-to-solar clutter ratio. These filters were evaluated near the potassium D1 and D2 doublet emission lines that occur at 769.89 and 766.49 nm respectively that are observed where projectile propellants are used. The maximum spectral radiance, from the AK-47 muzzle flash, is 1.88 x 10-2 W/cm2 str micron, and is approximately equal to the daytime atmospheric spectral radiance. The increased emission, due to the potassium doublet lines, and decreased atmospheric transmission, due to oxygen absorption, combine to create a condition where the signal-to-solar clutter ratio is greater than 1. The 3 nm filter, has a signal-to-solar clutter ratio of 2.09 when centered at 765.37 nm and provides the best combination of both cost and signal sensitivity.

Comparative seasonal variations of spectral signatures of broad-leaved and coniferous stands from Landsat data. Comparison with other perennial environments

International Nuclear Information System (INIS)

Chaume, R.; Combeau, A.

1984-01-01

Spectral signatures of two distinct forest test areas were identified from digital data including 15 LANDSAT scenes covering the same geographical area: a broad-leaved forest (oak and beech) and a coniferous forest (scotch pine). Seasonal variations of the signatures were examined and were expressed in terms of various data: date, solar height and phenological state of vegetation cover. Results were compared to these obtained from other perennial surface conditions (grassland, bare soils) . Range of the seasonal variations of radiance is noted, as well as evolutionary peculiarities on each band and between themes. Rationing of spectral bands (particularly MSS 5 and 7) and their variation with time are specified [fr

Nimbus-4 Infrared Interferometer Spectrometer (IRIS) Level 1 Radiance Data V001

Data.gov (United States)

National Aeronautics and Space Administration — The Nimbus-4 Infrared Interferometer Spectrometer (IRIS) Level 1 Radiance Data contain thermal emissions of the Earth's atmosphere at wave numbers between 400 and...

Limewashed mural paintings as seen by VIS-IR reflectography

Science.gov (United States)

Fontana, R.; Striova, J.; Barucci, M.; Pampaloni, E.; Raffaelli, M.; Pezzati, L.; Mariotti, P.

2015-06-01

Near-Infrared (NIR) reflectography is a well-established technique for painting diagnostics, offering a fundamental contribution to the conservation of paintings. Since the '80s it has been routinely applied to study the execution technique of the author, as well as the presence of pentimenti, retouches, integrations or underdrawing. In the last decades IR reflectography has been extended to the visible (VIS) spectral range, providing information about the pigment composition. Up to now the multispectral analysis is still applied at an experimental level, as the processing of the image set is not straightforward. Rarely multispectral VIS-IR application has been applied to frescos, probably due to the lack, in most cases, of a scattering background. In this work we present the results provided by a multispectral scanning device based on single sensor acquisition, working in the 380-2500 nm spectral range, that is a laboratory prototype specifically built for research-grade imaging. The technique have been applied on a mock up simulating a mural painting substrate where an underdrawing, made of either carbon or iron-gall ink, was covered by different surface layers of limewash, the so-called scialbo.

Diagnostics of Coronal Magnetic Fields through the Hanle Effect in UV and IR Lines

Energy Technology Data Exchange (ETDEWEB)

Raouafi, Nour E. [The John Hopkins University Applied Physics Laboratory, Laurel, MD (United States); Riley, Pete [Predictive Science Inc., San Diego, CA (United States); Gibson, Sarah [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO (United States); Fineschi, Silvano [The Astrophysical Observatory of Turin, National Institute for Astrophysics, Turin (Italy); Solanki, Sami K., E-mail: noureddine.raouafi@jhuapl.edu [Max-Planck-Institut für Sonnensystemforschung, Göttingen (Germany); School of Space Research, Kyung Hee University, Yongin, South (Korea, Republic of)

2016-06-22

The plasma thermodynamics in the solar upper atmosphere, particularly in the corona, are dominated by the magnetic field, which controls the flow and dissipation of energy. The relative lack of knowledge of the coronal vector magnetic field is a major handicap for progress in coronal physics. This makes the development of measurement methods of coronal magnetic fields a high priority in solar physics. The Hanle effect in the UV and IR spectral lines is a largely unexplored diagnostic. We use magnetohydrodynamic (MHD) simulations to study the magnitude of the signal to be expected for typical coronal magnetic fields for selected spectral lines in the UV and IR wavelength ranges, namely the H i Ly-α and the He i 10,830 Å lines. We show that the selected lines are useful for reliable diagnosis of coronal magnetic fields. The results show that the combination of polarization measurements of spectral lines with different sensitivities to the Hanle effect may be most appropriate for deducing coronal magnetic properties from future observations.

Attenuated total reflection design for in situ FT-IR spectroelectrochemical studies

International Nuclear Information System (INIS)

Visser, Hendrik; Curtright, Aimee E.; McCusker, James K.; Sauer, Kenneth

2000-01-01

A versatile spectroelectrochemical apparatus is introduced to study the changes in IR spectra of organic and inorganic compounds upon oxidation or reduction. The design is based on an attenuated total reflection (ATR) device, which permits the study of a wide spectral range of 16,700 cm-1 (600 nm) - 250 cm-1 with a small opaque region of 2250 - 1900 cm-1. In addition, an IR data collection protocol is introduced to deal with electrochemically non-reversible background signals. This method is tested with ferrocene in acetonitrile, producing results that agree with those in the literature

Deep convective cloud characterizations from both broadband imager and hyperspectral infrared sounder measurements

Science.gov (United States)

Ai, Yufei; Li, Jun; Shi, Wenjing; Schmit, Timothy J.; Cao, Changyong; Li, Wanbiao

2017-02-01

Deep convective storms have contributed to airplane accidents, making them a threat to aviation safety. The most common method to identify deep convective clouds (DCCs) is using the brightness temperature difference (BTD) between the atmospheric infrared (IR) window band and the water vapor (WV) absorption band. The effectiveness of the BTD method for DCC detection is highly related to the spectral resolution and signal-to-noise ratio (SNR) of the WV band. In order to understand the sensitivity of BTD to spectral resolution and SNR for DCC detection, a BTD to noise ratio method using the difference between the WV and IR window radiances is developed to assess the uncertainty of DCC identification for different instruments. We examined the case of AirAsia Flight QZ8501. The brightness temperatures (Tbs) over DCCs from this case are simulated for BTD sensitivity studies by a fast forward radiative transfer model with an opaque cloud assumption for both broadband imager (e.g., Multifunction Transport Satellite imager, MTSAT-2 imager) and hyperspectral IR sounder (e.g., Atmospheric Infrared Sounder) instruments; we also examined the relationship between the simulated Tb and the cloud top height. Results show that despite the coarser spatial resolution, BTDs measured by a hyperspectral IR sounder are much more sensitive to high cloud tops than broadband BTDs. As demonstrated in this study, a hyperspectral IR sounder can identify DCCs with better accuracy.

Analysis of cirrus cloud spectral signatures in the far infrared

International Nuclear Information System (INIS)

Maestri, T.; Rizzi, R.; Tosi, E.; Veglio, P.; Palchetti, L.; Bianchini, G.; Di Girolamo, P.; Masiello, G.; Serio, C.; Summa, D.

2014-01-01

This paper analyses high spectral resolution downwelling radiance measurements in the far infrared in the presence of cirrus clouds taken by the REFIR-PAD interferometer, deployed at 3500 m above the sea level at the Testa Grigia station (Italy), during the Earth COoling by WAter vapouR emission (ECOWAR) campaign. Atmospheric state and cloud geometry are characterised by the co-located millimeter-wave spectrometer GBMS and by radiosonde profile data, an interferometer (I-BEST) and a Raman lidar system deployed at a nearby location (Cervinia). Cloud optical depth and effective diameter are retrieved from REFIR-PAD data using a limited number of channels in the 820–960 cm −1 interval. The retrieved cloud parameters are the input data for simulations covering the 250–1100 cm −1 band in order to test our ability to reproduce the REFIR-PAD spectra in the presence of ice clouds. Inverse and forward simulations are based on the same radiative transfer code. A priori information concerning cloud ice vertical distribution is used to better constrain the simulation scheme and an analysis of the degree of approximation of the phase function within the radiative transfer codes is performed to define the accuracy of computations. Simulation-data residuals over the REFIR-PAD spectral interval show an excellent agreement in the window region, but values are larger than total measurement uncertainties in the far infrared. Possible causes are investigated. It is shown that the uncertainties related to the water vapour and temperature profiles are of the same order as the sensitivity to the a priori assumption on particle habits for an up-looking configuration. In case of a down-looking configuration, errors due to possible incorrect description of the water vapour profile would be drastically reduced. - Highlights: • We analyze down-welling spectral radiances in the far infrared (FIR) spectrum. • Discuss the scattering in the fir and the ice crystals phase function

ASTER Expedited L1B Registered Radiance at the Sensor V003

Data.gov (United States)

National Aeronautics and Space Administration — The Expedited ASTER Level-1B Registered Radiance at the Sensor data set is produced with the express purpose of providing ASTER Science Team members data of their...

Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

Directory of Open Access Journals (Sweden)

Sagar Dhakal

2016-05-01

Full Text Available Turmeric powder (Curcuma longa L. is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman and Fourier Transform-Infra Red (FT-IR spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0.01% (w/w. FT-Raman and FT-IR spectra were acquired for these mixture samples as well as for pure samples of turmeric powder and metanil yellow. Spectral analysis showed that the FT-IR method in this study could detect the metanil yellow at the 5% concentration, while the FT-Raman method appeared to be more sensitive and could detect the metanil yellow at the 1% concentration. Relationships between metanil yellow spectral peak intensities and metanil yellow concentration were established using representative peaks at FT-Raman 1406 cm−1 and FT-IR 1140 cm−1 with correlation coefficients of 0.93 and 0.95, respectively.

RESOLVING THE ACTIVE GALACTIC NUCLEUS AND HOST EMISSION IN THE MID-INFRARED USING A MODEL-INDEPENDENT SPECTRAL DECOMPOSITION

Energy Technology Data Exchange (ETDEWEB)

Hernán-Caballero, Antonio; Alonso-Herrero, Almudena [Instituto de Física de Cantabria, CSIC-UC, Avenida de los Castros s/n, E-39005, Santander (Spain); Hatziminaoglou, Evanthia [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Spoon, Henrik W. W. [Cornell University, CRSR, Space Sciences Building, Ithaca, NY 14853 (United States); Almeida, Cristina Ramos [Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Santos, Tanio Díaz [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Hönig, Sebastian F. [School of Physics and Astronomy, University of Southampton, Southampton SO18 1BJ (United Kingdom); González-Martín, Omaira [Centro de Radioastronomía y Astrofísica (CRyA-UNAM), 3-72 (Xangari), 8701, Morelia (Mexico); Esquej, Pilar, E-mail: ahernan@ifca.unican.es [Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

2015-04-20

We present results on the spectral decomposition of 118 Spitzer Infrared Spectrograph (IRS) spectra from local active galactic nuclei (AGNs) using a large set of Spitzer/IRS spectra as templates. The templates are themselves IRS spectra from extreme cases where a single physical component (stellar, interstellar, or AGN) completely dominates the integrated mid-infrared emission. We show that a linear combination of one template for each physical component reproduces the observed IRS spectra of AGN hosts with unprecedented fidelity for a template fitting method with no need to model extinction separately. We use full probability distribution functions to estimate expectation values and uncertainties for observables, and find that the decomposition results are robust against degeneracies. Furthermore, we compare the AGN spectra derived from the spectral decomposition with sub-arcsecond resolution nuclear photometry and spectroscopy from ground-based observations. We find that the AGN component derived from the decomposition closely matches the nuclear spectrum with a 1σ dispersion of 0.12 dex in luminosity and typical uncertainties of ∼0.19 in the spectral index and ∼0.1 in the silicate strength. We conclude that the emission from the host galaxy can be reliably removed from the IRS spectra of AGNs. This allows for unbiased studies of the AGN emission in intermediate- and high-redshift galaxies—currently inaccesible to ground-based observations—with archival Spitzer/IRS data and in the future with the Mid-InfraRed Instrument of the James Webb Space Telescope. The decomposition code and templates are available at http://denebola.org/ahc/deblendIRS.

An interactive RADIANCE toolkit for customizable CT dose monitoring and reporting.

Science.gov (United States)

Cook, Tessa S; Sundaram, Anand; Boonn, William W; Kim, Woojin

2013-08-01

The need for tools to monitor imaging-related radiation has grown dramatically in recent years. RADIANCE, a freely available open-source dose-monitoring tool, was developed in response to the need for an informatics solution in this realm. A number of open-source as well as commercial solutions have since been developed to enable radiology practices to monitor radiation dose parameters for modalities ranging from computed tomography to radiography to fluoroscopy. However, it is not sufficient to simply collect this data; it is equally important to be able to review it in the appropriate context. Most of the currently available dose-monitoring solutions have some type of reporting capability, such as a real-time dashboard or a static report. Previous versions of RADIANCE have included a real-time dashboard with pre-set screens that plot effective dose estimates according to different criteria, as well as monthly scorecards to summarize dose estimates for individuals within a radiology practice. In this work, we present the RADIANCE toolkit, a customizable reporting solution that allows users to generate reports of interest to them, summarizing a variety of metrics that can be grouped according to useful parameters. The output of the toolkit can be used for real-time dose monitoring or scheduled reporting, such as to a quality assurance committee. Making dose parameter data more accessible and more meaningful to the user promotes dose reduction efforts such as regular protocol review and optimization, and ultimately improves patient care by decreasing unnecessary radiation exposure.

Practical Atmospheric Correction Algorithms for a Multi-Spectral Sensor From the Visible Through the Thermal Spectral Regions

Energy Technology Data Exchange (ETDEWEB)

Borel, C.C.; Villeneuve, P.V.; Clodium, W.B.; Szymenski, J.J.; Davis, A.B.

1999-04-04

Deriving information about the Earth's surface requires atmospheric corrections of the measured top-of-the-atmosphere radiances. One possible path is to use atmospheric radiative transfer codes to predict how the radiance leaving the ground is affected by the scattering and attenuation. In practice the atmosphere is usually not well known and thus it is necessary to use more practical methods. The authors will describe how to find dark surfaces, estimate the atmospheric optical depth, estimate path radiance and identify thick clouds using thresholds on reflectance and NDVI and columnar water vapor. The authors describe a simple method to correct a visible channel contaminated by a thin cirrus clouds.

UV, visible, and near-IR reflectivity data for magnetic soils/rocks from Brazil

Science.gov (United States)

Vempati, R. K.; Morris, R. V.; Lauer, H. V., Jr.; Coey, J. M. D.

1991-01-01

The objective is to obtain UV, visible, and near-IR reflectivity spectra for several magnetic Brazilian soils/rocks and compare them to corresponding data for Mars to see if these materials satisfy both magnetic and spectral constraints for Mars. Selected physical properties of the magnetic Brazilian soils/rocks are presented. In general, the spectral features resulting from ferric crystal-field transitions are much better defined in the spectra of the magnetic Brazilian soils/rocks than in Martian spectral data. Presumably, this results from a relatively higher proportion of crystalline ferric oxides for the former. The apparent masking of the spectral signature of maghemite by hematite or goethite for the Brazilian samples implies the magnetic and spectral constraints for Mars can be decoupled. That is, maghemite may be present in magnetically-significant but optically-insignificant amounts compared to crystalline hematite.

Retrieving mesospheric water vapour from observations of volume scattering radiances

Directory of Open Access Journals (Sweden)

P. Vergados

2009-02-01

Full Text Available This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC using satellite observations of Volume Scattering Radiances (VSR obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/−-IRS-1+/− Double Heterozygous (IR-IRS1dh Mice

Directory of Open Access Journals (Sweden)

Andras Franko

2017-05-01

Full Text Available Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR+/−-insulin receptor substrate-1 (IRS-1+/− double heterozygous (IR-IRS1dh mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver.

Multispectral simulation environment for modeling low-light-level sensor systems

Science.gov (United States)

Ientilucci, Emmett J.; Brown, Scott D.; Schott, John R.; Raqueno, Rolando V.

1998-11-01

Image intensifying cameras have been found to be extremely useful in low-light-level (LLL) scenarios including military night vision and civilian rescue operations. These sensors utilize the available visible region photons and an amplification process to produce high contrast imagery. It has been demonstrated that processing techniques can further enhance the quality of this imagery. For example, fusion with matching thermal IR imagery can improve image content when very little visible region contrast is available. To aid in the improvement of current algorithms and the development of new ones, a high fidelity simulation environment capable of producing radiometrically correct multi-band imagery for low- light-level conditions is desired. This paper describes a modeling environment attempting to meet these criteria by addressing the task as two individual components: (1) prediction of a low-light-level radiance field from an arbitrary scene, and (2) simulation of the output from a low- light-level sensor for a given radiance field. The radiance prediction engine utilized in this environment is the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model which is a first principles based multi-spectral synthetic image generation model capable of producing an arbitrary number of bands in the 0.28 to 20 micrometer region. The DIRSIG model is utilized to produce high spatial and spectral resolution radiance field images. These images are then processed by a user configurable multi-stage low-light-level sensor model that applies the appropriate noise and modulation transfer function (MTF) at each stage in the image processing chain. This includes the ability to reproduce common intensifying sensor artifacts such as saturation and 'blooming.' Additionally, co-registered imagery in other spectral bands may be simultaneously generated for testing fusion and exploitation algorithms. This paper discusses specific aspects of the DIRSIG radiance prediction for low

Limb darkening in Venus night-side disk as viewed from Akatsuki IR2

Science.gov (United States)

Satoh, Takehiko; Nakakushi, Takashi; Sato, Takao M.; Hashimoto, George L.

2017-10-01

Night-side hemisphere of Venus exhibits dark and bright regions as a result of spatially inhomogeneous cloud opacity which is illuminated by infrared radiation from deeper atmosphere. The 2-μm camera (IR2) onboard Akatsuki, Japan's Venus Climate Orbiter, is equipped with three narrow-band filters (1.735, 2.26, and 2.32 μm) to image Venus night-side disk in well-known transparency windows of CO2 atmosphere (Allen and Crawford 1984). In general, a cloud feature appears brightest when it is in the disk center and becomes darker as the zenith angle of emergent light increases. Such limb darkening was observed with Galileo/NIMS and mathematically approximated (Carlson et al., 1993). Limb-darkening correction helps to identify branches, in a 1.74-μm vs. 2.3-μm radiances scatter plot, each of which corresponds to a group of aerosols with similar properties. We analyzed Akatsuki/IR2 images to characterize the limb darkening for three night-side filters.There is, however, contamination from the intense day-side disk blurred by IR2's point spread function (PSF). It is found that infrared light can be multiplly reflected within the Si substrate of IR2 detector (1024x1024 pixels PtSi array), causing elongated tail in the actual PSF. We treated this in two different ways. One is to mathematically approximate the PSF (with a combination of modified Lorentz functions) and another is to differentiate 2.26-μm image from 2.32-μm image so that the blurred light pattern can directly be obtained. By comparing results from these two methods, we are able to reasonablly clean up the night-side images and limb darkening is extracted. Physical interpretation of limb darkening, as well as "true" time variations of cloud brightness will be presented/discussed.

Pulsed photothermal profiling of water-based samples using a spectrally composite reconstruction approach

International Nuclear Information System (INIS)

Majaron, B; Milanic, M

2010-01-01

Pulsed photothermal profiling involves reconstruction of temperature depth profile induced in a layered sample by single-pulse laser exposure, based on transient change in mid-infrared (IR) emission from its surface. Earlier studies have indicated that in watery tissues, featuring a pronounced spectral variation of mid-IR absorption coefficient, analysis of broadband radiometric signals within the customary monochromatic approximation adversely affects profiling accuracy. We present here an experimental comparison of pulsed photothermal profiling in layered agar gel samples utilizing a spectrally composite kernel matrix vs. the customary approach. By utilizing a custom reconstruction code, the augmented approach reduces broadening of individual temperature peaks to 14% of the absorber depth, in contrast to 21% obtained with the customary approach.

Radiation from an equilibrium CO2-N2 plasma in the [250-850 nm] spectral region: II. Spectral modelling

International Nuclear Information System (INIS)

Silva, M Lino da; Vacher, D; Andre, P; Faure, G; Dudeck, M

2008-01-01

In the first part of this work, described in a previous paper, the thermodynamic conditions in an atmospheric pressure inductively coupled CO 2 -N 2 plasma have been determined, and the radiation emission spectrum has been measured and calibrated in the [250-850 nm] spectral region. In the second part of this work, a synthetic radiation spectrum is obtained taking into account (a) the geometry of the plasma torch and (b) the local thermodynamic conditions of the plasma. This synthetic spectrum has then been compared against the measured spectrum. The good agreement between the two spectra allows validating the spectral database of the line-by-line code SPARTAN for the simulation of the radiative emission of CO 2 -N 2 plasmas from the near-UV to the near-IR spectral region.

TRMM Visible and Infrared Scanner Calibrated Radiances L1B 1.5 hours V7 (TRMM_1B01) at GES DISC

Data.gov (United States)

National Aeronautics and Space Administration — This TRMM Visible and Infrared Scanner (VIRS) Level 1B Calibrated Radiance Product (1B01) contains calibrated radiances and auxiliary geolocation information from...

Specific features of diffuse reflection of human face skin for laser and non-laser sources of visible and near-IR light

International Nuclear Information System (INIS)

Dolotov, L E; Sinichkin, Yu P; Tuchin, Valerii V; Al'tshuler, G B; Yaroslavskii, I V

2011-01-01

The specific features of diffuse reflection from different areas of human face skin for laser and non-laser sources of visible and near-IR light have been investigated to localise the closed-eye (eyelid) region. In the visible spectral range the reflection from the eyelid skin surface can be differentiated by measuring the slope of the spectral dependence of the effective optical density of skin in the wavelength range from 650 to 700nm. In the near-IR spectral range the reflectances of the skin surface at certain wavelengths, normalised to the forehead skin reflectance, can be used as a criterion for differentiating the eyelid skin. In this case, a maximum discrimination is obtained when measuring the skin reflectances at laser wavelengths of 1310 and 1470nm, which correspond to the spectral ranges of maximum and minimum water absorption. (optical technologies in biophysics and medicine)

Synthesis and IR spectral study of MoO2Cl2 molecular complex with acetoacetanilides. Crystal structure of MoO2Cl2 complex with acetoacet-2-toluidine

International Nuclear Information System (INIS)

Abramenko, V.L.; Sergienko, V.S.; Churakov, A.V.

2000-01-01

Certain MoO 2 Cl 2 complexes with acetoacetanilide derivatives were synthesized, two IR spectral study being performed. Crystal and molecular structure of MoO 2 Cl 2 complex with acetoacet-2-toluidine (HL) was determined using X-ray diffraction analysis. The crystals are monoclinic, a = 7.621 (7), b = 9.498 (3), c = 19.980 (9) A, β = 95.16 (7), Z = 4, sp.gr. P2 1 /n. Coordination polyhedron of Mo atom is a distorted octahedron with two O oxoatoms in cis-position, two Cl atom in mutual trans-position and two O(HL) atoms in trans-positions in reference to O(oxo) [ru

Simultaneous determination of aerosol optical thickness and water-leaving radiance from multispectral measurements in coastal waters

Science.gov (United States)

Shi, Chong; Nakajima, Teruyuki

2018-03-01

Retrieval of aerosol optical properties and water-leaving radiance over ocean is challenging since the latter mostly accounts for ˜ 10 % of the satellite-observed signal and can be easily influenced by the atmospheric scattering. Such an effort would be more difficult in turbid coastal waters due to the existence of optically complex oceanic substances or high aerosol loading. In an effort to solve such problems, we present an optimization approach for the simultaneous determination of aerosol optical thickness (AOT) and normalized water-leaving radiance (nLw) from multispectral satellite measurements. In this algorithm, a coupled atmosphere-ocean radiative transfer model combined with a comprehensive bio-optical oceanic module is used to jointly simulate the satellite-observed reflectance at the top of atmosphere and water-leaving radiance just above the ocean surface. Then, an optimal estimation method is adopted to retrieve AOT and nLw iteratively. The algorithm is validated using Aerosol Robotic Network - Ocean Color (AERONET-OC) products selected from eight OC sites distributed over different waters, consisting of observations that covered glint and non-glint conditions from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. Results show a good consistency between retrieved and in situ measurements at each site. It is demonstrated that more accurate AOTs are determined based on the simultaneous retrieval method, particularly in shorter wavelengths and sunglint conditions, where the averaged percentage difference (APD) of retrieved AOT is generally reduced by approximate 10 % in visible bands compared with those derived from the standard atmospheric correction (AC) scheme, since all the spectral measurements can be used jointly to increase the information content in the inversion of AOT, and the wind speed is also simultaneously retrieved to compensate the specular reflectance error estimated from the rough ocean surface model. For the

General review of multispectral cooled IR development at CEA-Leti, France

Science.gov (United States)

Boulard, F.; Marmonier, F.; Grangier, C.; Adelmini, L.; Gravrand, O.; Ballet, P.; Baudry, X.; Baylet, J.; Badano, G.; Espiau de Lamaestre, R.; Bisotto, S.

2017-02-01

Multicolor detection capabilities, which bring information on the thermal and chemical composition of the scene, are desirable for advanced infrared (IR) imaging systems. This communication reviews intra and multiband solutions developed at CEA-Leti, from dual-band molecular beam epitaxy grown Mercury Cadmium Telluride (MCT) photodiodes to plasmon-enhanced multicolor IR detectors and backside pixelated filters. Spectral responses, quantum efficiency and detector noise performances, pros and cons regarding global system are discussed in regards to technology maturity, pixel pitch reduction, and affordability. From MWIR-LWIR large band to intra MWIR or LWIR bands peaked detection, results underline the full possibility developed at CEA-Leti.

Spectral responsivity-based calibration of photometer and colorimeter standards

Science.gov (United States)

Eppeldauer, George P.

2013-08-01

Several new generation transfer- and working-standard illuminance meters and tristimulus colorimeters have been developed at the National Institute of Standards and Technology (NIST) [1] to measure all kinds of light sources with low uncertainty. The spectral and broad-band (illuminance) responsivities of the photometer (Y) channels of two tristimulus meters were determined at both the Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) facility and the Spectral Comparator Facility (SCF) [2]. The two illuminance responsivities agreed within 0.1% with an overall uncertainty of 0.2% (k = 2), which is a factor of two improvement over the present NIST photometric scale. The first detector-based tristimulus color scale [3] was realized. All channels of the reference tristimulus colorimeter were calibrated at the SIRCUS. The other tristimulus meters were calibrated at the SCF and also against the reference meter on the photometry bench in broad-band measurement mode. The agreement between detector- and source-based calibrations was within 3 K when a tungsten lamp-standard was measured at 2856 K and 3100 K [4]. The color-temperature uncertainty of tungsten lamp measurements was 4 K (k = 2) between 2300 K and 3200 K, which is a factor of two improvement over the presently used NIST source-based color temperature scale. One colorimeter was extended with an additional (fifth) channel to apply software implemented matrix corrections. With this correction, the spectral mismatch caused color difference errors were decreased by a factor of 20 for single-color LEDs.

Enhanced spectral emissivity of CeO2 coating with cauliflower-like microstructure

International Nuclear Information System (INIS)

Huang Jianping; Li Yibin; He Xiaodong; Song Guangping; Fan Chenglei; Sun Yue; Fei Weidong; Du Shanyi

2012-01-01

Highlights: ► Cauliflower-like microstructured CeO 2 coating is prepared on Ni based substrate. ► The infrared emissive property at high temperature is investigated. ► Rough CeO 2 coating shows high emissivity, that is, 0.9 at 873 K and 0.87 at 1073 K. ► The emissivity enhancement mechanisms for the rough CeO 2 coating are discussed. - Abstract: Cerium dioxide is a transparent oxide with high refractive index (from 1.6 to 2.5 at 633 nm) in the visible and near-IR spectral regions. However, little attention has been paid to its optical property in mid-IR (2.5–25 μm). Here we report that the cauliflower-like microstructured CeO 2 coating deposited by electron beam physical vapor deposition technique shows high emissivity up to 0.9 at 873 K in the mid-IR spectral region. The high emissivity is attributed to the coupling between free propagating waves and space-variant polarizations caused by the cauliflower-like microstructure. This high emissivity coating shows a potential application in high temperature components.

Recent Characterization of the Night-Sky Irradiance in the Visible/Near-Infrared Spectral Band

Science.gov (United States)

Moore, Carolynn; Wood, Michael; Bender, Edward; Hart, Steve

2018-01-01

The U.S. Army RDECOM CERDEC NVESD has made numerous characterizations of the night sky over the past 45 years. Up until the last four years, the measurement devices were highly detector-limited, which led to low spectral resolution, marginal sensitivity in no-moon conditions, and the need for inferential analysis of the resulting data. In 2014, however, the PhotoResearch Model PR-745 spectro-radiometer established a new state of the art for measurement of the integrated night-sky irradiance over the Visible-to-Near-Infrared (VNIR) spectral band (400-1050nm). This has enabled characterization of no-moon night-sky irradiance with a spectral bandwidth less than 15 nanometers, even when this irradiance is attenuated by heavy clouds or forest canopy. Since 2014, we have conducted a series of night-sky data collections at remote sites across the United States. The resulting data has provided new insights into natural radiance variations, cultural lighting impacts, and the spectrally-varying attenuation caused by cloud cover and forest canopy. Several new metrics have also been developed to provide insight into these newly-found components and temporal variations. The observations, findings and conclusions of the above efforts will be presented, including planned near-term efforts to further characterize the night-sky irradiance in the Visible/Near-Infrared spectral band.

Sandmeier model based topographic correction to lunar spectral profiler (SP) data from KAGUYA satellite.

Science.gov (United States)

Chen, Sheng-Bo; Wang, Jing-Ran; Guo, Peng-Ju; Wang, Ming-Chang

2014-09-01

The Moon may be considered as the frontier base for the deep space exploration. The spectral analysis is one of the key techniques to determine the lunar surface rock and mineral compositions. But the lunar topographic relief is more remarkable than that of the Earth. It is necessary to conduct the topographic correction for lunar spectral data before they are used to retrieve the compositions. In the present paper, a lunar Sandmeier model was proposed by considering the radiance effect from the macro and ambient topographic relief. And the reflectance correction model was also reduced based on the Sandmeier model. The Spectral Profile (SP) data from KAGUYA satellite in the Sinus Iridum quadrangle was taken as an example. And the digital elevation data from Lunar Orbiter Laser Altimeter are used to calculate the slope, aspect, incidence and emergence angles, and terrain-viewing factor for the topographic correction Thus, the lunar surface reflectance from the SP data was corrected by the proposed model after the direct component of irradiance on a horizontal surface was derived. As a result, the high spectral reflectance facing the sun is decreased and low spectral reflectance back to the sun is compensated. The statistical histogram of reflectance-corrected pixel numbers presents Gaussian distribution Therefore, the model is robust to correct lunar topographic effect and estimate lunar surface reflectance.

Wide-band IR imaging in the NIR-MIR-FIR regions for in situ analysis of frescoes

Science.gov (United States)

Daffara, C.; Pezzati, L.; Ambrosini, D.; Paoletti, D.; Di Biase, R.; Mariotti, P. I.; Frosinini, C.

2011-06-01

Imaging methods offer several advantages in the field of conservation allowing to perform non-invasive inspection of works of art. In particular, non-invasive techniques based on imaging in different infrared (IR) regions are widely used for the investigation of paintings. Using radiation beyond the visible range, different characteristics of the inspected artwork may be revealed according to the bandwidth acquired. In this paper we present the recent results of a joint project among the two research institutes DIMEG and CNR-INO, and the restoration facility Opificio delle Pietre Dure, concerning the wide-band integration of IR imaging techniques, in the spectral ranges NIR 0.8-2.5 μm, MIR 3-5 μm, and FIR 8-12 μm, for in situ analysis of artworks. A joint, multi-mode use of reflection and thermal bands is proposed for the diagnostics of mural paintings, and it is demonstrated to be an effective tool in inspecting the layered structure. High resolution IR reflectography and, to a greater extent, IR imaging in the 3-5 μm band, are effectively used to characterize the superficial layer of the fresco and to analyze the stratigraphy of different pictorial layers. IR thermography in the 8-12 μm band is used to characterize the support deep structure. The integration of all the data provides a multi- layered and multi-spectral representation of the fresco that yields a comprehensive analysis.

Assessment of a Bidirectional Reflectance Distribution Correction of Above-Water and Satellite Water-Leaving Radiance in Coastal Waters

Science.gov (United States)

Hlaing, Soe; Gilerson, Alexander; Harmal, Tristan; Tonizzo, Alberto; Weidemann, Alan; Arnone, Robert; Ahmed, Samir

2012-01-01

Water-leaving radiances, retrieved from in situ or satellite measurements, need to be corrected for the bidirectional properties of the measured light in order to standardize the data and make them comparable with each other. The current operational algorithm for the correction of bidirectional effects from the satellite ocean color data is optimized for typical oceanic waters. However, versions of bidirectional reflectance correction algorithms specifically tuned for typical coastal waters and other case 2 conditions are particularly needed to improve the overall quality of those data. In order to analyze the bidirectional reflectance distribution function (BRDF) of case 2 waters, a dataset of typical remote sensing reflectances was generated through radiative transfer simulations for a large range of viewing and illumination geometries. Based on this simulated dataset, a case 2 water focused remote sensing reflectance model is proposed to correct above-water and satellite water-leaving radiance data for bidirectional effects. The proposed model is first validated with a one year time series of in situ above-water measurements acquired by collocated multispectral and hyperspectral radiometers, which have different viewing geometries installed at the Long Island Sound Coastal Observatory (LISCO). Match-ups and intercomparisons performed on these concurrent measurements show that the proposed algorithm outperforms the algorithm currently in use at all wavelengths, with average improvement of 2.4% over the spectral range. LISCO's time series data have also been used to evaluate improvements in match-up comparisons of Moderate Resolution Imaging Spectroradiometer satellite data when the proposed BRDF correction is used in lieu of the current algorithm. It is shown that the discrepancies between coincident in-situ sea-based and satellite data decreased by 3.15% with the use of the proposed algorithm.

Development of Multi-Sensor Global Cloud and Radiance Composites for DSCOVR EPIC Imager with Subpixel Definition

Science.gov (United States)

Khlopenkov, K. V.; Duda, D. P.; Thieman, M. M.; Sun-Mack, S.; Su, W.; Minnis, P.; Bedka, K. M.

2017-12-01

The Deep Space Climate Observatory (DSCOVR) is designed to study the daytime Earth radiation budget by means of onboard Earth Polychromatic Imaging Camera (EPIC) and National Institute of Standards and Technology Advanced Radiometer (NISTAR). EPIC imager observes in several shortwave bands (317-780 nm), while NISTAR measures the top-of-atmosphere (TOA) whole-disk radiance in shortwave and total broadband windows. Calculation of albedo and outgoing longwave flux requires a high-resolution scene identification such as the radiance observations and cloud property retrievals from low earth orbit and geostationary satellite imagers. These properties have to be co-located with EPIC imager pixels to provide scene identification and to select anisotropic directional models, which are then used to adjust the NISTAR-measured radiance and subsequently obtain the global daytime shortwave and longwave fluxes. This work presents an algorithm for optimal merging of selected radiances and cloud properties derived from multiple satellite imagers to obtain seamless global hourly composites at 5-km resolution. The highest quality observation is selected by means of an aggregated rating which incorporates several factors such as the nearest time relative to EPIC observation, lowest viewing zenith angle, and others. This process provides a smoother transition and avoids abrupt changes in the merged composite data. Higher spatial accuracy in the composite product is achieved by using the inverse mapping with gradient search during reprojection and bicubic interpolation for pixel resampling. The composite data are subsequently remapped into the EPIC-view domain by convolving composite pixels with the EPIC point spread function (PSF) defined with a half-pixel accuracy. Within every EPIC footprint, the PSF-weighted average radiances and cloud properties are computed for each cloud phase and then stored within five data subsets (clear-sky, water cloud, ice cloud, total cloud, and no

Relationship of red and photographic infrared spectral radiances to alfalfa biomass, forage water content, percentage canopy cover, and severity of drought stress

Science.gov (United States)

Tucker, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

1979-01-01

Red and photographic infrared spectral data were collected using a handheld radiometer for two cuttings of alfalfa. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover for the earlier alfalfa cutting. The alfalfa of later cutting experienced a period of severe drought stress which limited growth. The spectral variables were found to be highly correlated with the estimated drought scores for this alfalfa cutting.

Wide-field Spatio-Spectral Interferometry: Bringing High Resolution to the Far- Infrared

Science.gov (United States)

Leisawitx, David

Wide-field spatio-spectral interferometry combines spatial and spectral interferometric data to provide integral field spectroscopic information over a wide field of view. This technology breaks through a mission cost barrier that stands in the way of resolving spatially and measuring spectroscopically at far-infrared wavelengths objects that will lead to a deep understanding of planetary system and galaxy formation processes. A space-based far-IR interferometer will combine Spitzer s superb sensitivity with a two order of magnitude gain in angular resolution, and with spectral resolution in the thousands. With the possible exception of detector technology, which is advancing with support from other research programs, the greatest challenge for far-IR interferometry is to demonstrate that the interferometer will actually produce the images and spectra needed to satisfy mission science requirements. With past APRA support, our team has already developed the highly specialized hardware testbed, image projector, computational model, and image construction software required for the proposed effort, and we have access to an ideal test facility.

Gaz Phase IR and UV Spectroscopy of Neutral Contact Ion Pairs

Science.gov (United States)

Habka, Sana; Brenner, Valerie; Mons, Michel; Gloaguen, Eric

2016-06-01

Cations and anions, in solution, tend to pair up forming ion pairs. They play a crucial role in many fundamental processes in ion-concentrated solutions and living organisms. Despite their importance and vast applications in physics, chemistry and biochemistry, they remain difficult to characterize namely because of the coexistence of several types of pairing in solution. However, an interesting alternative consists in applying highly selective gas phase spectroscopy which can offer new insights on these neutral ion pairs. Our study consists in characterizing contact ion pairs (CIPs) in isolated model systems (M+, Ph-(CH2)n-COO- with M=Li, Na, K, Rb, Cs, and n=1-3), to determine their spectral signatures and compare them to ion pairs in solution. We have used laser desorption to vaporize a solid tablet containing the desired salt. Structural information for each system was obtained by mass-selective, UV and IR laser spectroscopy combined with high level quantum chemistry calculations1. Evidence of the presence of neutral CIPs was found by scanning the π-π* transition of the phenyl ring using resonant two-photon ionization (R2PI). Then, conformational selective IR/UV double resonance spectra were recorded in the CO2- stretch region for each conformation detected. The good agreement between theoretical data obtained at the BSSE-corrected-fullCCSD(T)/dhf-TZVPP//B97-D3/dhf-TZVPP level and experimental IR spectra led us to assign the 3D structure for each ion pair formed. Spectral signatures of (M+, Ph-CH2-COO-) pairs, were assigned to a bidentate CIPs between the alkali cation and the carboxylate group. In the case of (Li+, Ph-(CH2)3-COO-) pairs, the presence of a flexible side chain promotes a cation-π interaction leading to a tridentate O-O-π structure with its unique IR and UV signatures. IR spectra obtained on isolated CIPs were found very much alike the ones published on lithium and sodium acetate in solution2. However, in the case of sodium acetate, solution

Estimation of spectral reflectance of snow from IRS-1D LISS-III ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

Marine and Water Resources Group, Space Applications Centre, Ahmedabad, 380 015, India. The sensor ... snowpack characteristics as a result of various metamorphic processes, with age, can cause varia- tions in its ... estimate the direct radiation income of slopes in ... model are: mean solar exo-atmospheric spectral.

Retrieving Temperature and Moisture Profiles from AERI Radiance Observations. AERIPROF Value-Added Product Technical Description

Energy Technology Data Exchange (ETDEWEB)

Feltz, W. F. [Univ. of Wisconsin, Madison, WI (United States); Howell, H. B. [Univ. of Wisconsin, Madison, WI (United; Knuteson, R. O. [Univ. of Wisconsin, Madison, WI (United States); Comstock, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mahon, R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Turner, D. D. [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); Smith, W. L. [NASA Langley Research Center, Hampton, VA (United States); Woolf, H. M. [Univ. of Wisconsin, Madison, WI (United; Sivaraman, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Halter, T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2007-04-01

One of the goals of the Atmospheric Radiation Measurement (ARM) Program is to collect a long-term series of radiative and atmospheric state observations to improve the parameterization of these processes in global climate models. The ARM Program intended to move away from the traditional approach of directly measuring profiles of temperature and moisture using radiosondes, which is expensive in terms of expendables and manpower, and develop methods to retrieve these profiles with ground-based remote sensors. The atmospheric emitted radiance interferometer (AERI), whose radiance data contains information on the vertical distribution of water vapor and temperature, is an integral part of the ARM profiling plan.

MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km - NRT

Data.gov (United States)

National Aeronautics and Space Administration — The MODIS Level 1B Near Real Time (NRT) data set contains calibrated and geolocated at-aperture radiances for 36 discrete bands located in the 0.4 to 14.4 micron...

FT-IR spectrum of grape seed oil and quantum models of fatty acids triglycerides

Science.gov (United States)

Berezin, K. V.; Antonova, E. M.; Shagautdinova, I. T.; Chernavina, M. L.; Dvoretskiy, K. N.; Grechukhina, O. N.; Vasilyeva, L. M.; Rybakov, A. V.; Likhter, A. M.

2018-04-01

FT-IR spectra of grape seed oil and glycerol were registered in the 650-4000 cm-1 range. Molecular models of glycerol and some fatty acids that compose the oil under study - linoleic, oleic, palmitic and stearic acids - as well as their triglycerides were developed within B3LYP/6-31G(d) density functional model. A vibrating FT-IR spectrum of grape seed oil was modeled on the basis of calculated values of vibrating wave numbers and IR intensities of the fatty acids triglycerides and with regard to their percentage. Triglyceride spectral bands that were formed by glycerol linkage vibrations were revealed. It was identified that triglycerol linkage has a small impact on the structure of fatty acids and, consequently, on vibrating wave numbers. The conducted molecular modeling became a basis for theoretical interpretation on 10 experimentally observed absorption bands in FT-IR spectrum of grape seed oil.

Test and evaluation of IR detectors and arrays II; Proceedings of the Meeting, Orlando, FL, Apr. 22, 23, 1992

Science.gov (United States)

Hoke, Forney M.

The present conference discusses a radiometric calibration system for IR cameras, a methodology for testing IR focal-plane arrays in simulated nuclear radiation environments, process optimization for Si:As In-bumped focal-plane arrays, precise MTF measurements for focal-plane arrays, and IR focal-plane array crosstalk measurement. Also discussed are an imaging metric for IR focal-plane arrays, optical stimuli for high-volume automated testing of 2D HgCdTe focal-plane arrays, the evaluation of a solid-state photomultiplier focal-plane array for SDI, spectral effects on bulk photoconductors operated at cryogenic temperatures, and a novel technique for measuring the ionizing radiation effects in MOS transistors.

IL 6: 2D-IR spectroscopy: chemistry and biophysics in real time

International Nuclear Information System (INIS)

Bredenbeck, Jens

2010-01-01

Pulsed multidimensional experiments, daily business in the field of NMR spectroscopy, have been demonstrated only relatively recently in IR spectroscopy. Similar as nuclear spins in multidimensional NMR, molecular vibrations are employed in multidimensional IR experiments as probes of molecular structure and dynamics, albeit with femtosecond time resolution. Different types of multidimensional IR experiments have been implemented, resembling basic NMR experiments such as NOESY, COSY and EXSY. In contrast to one-dimensional linear spectroscopy, such multidimensional experiments reveal couplings and correlations of vibrations, which are closely linked to molecular structure and its change in time. The use of mixed IR/VIS pulse sequences further extends the potential of multidimensional IR spectroscopy, enabling studies of ultrafast non-equilibrium processes as well as surface specific, highly sensitive experiments. A UV/VIS pulse preceding the IR pulse sequence can be used to prepare the system under study in a non-equilibrium state. 2D-IR snapshots of the evolving non-equilibrium system are then taken, for example during a photochemical reaction or during the photo-cycle of a light sensitive protein. Preparing the system in a non-equilibrium state by UV/Vis excitation during the IR pulse sequence allows for correlating states of reactant and product of the light triggered process via their 2D-IR cross peaks - a technique that has been used to map the connectivity between different binding sites of a ligand as it migrates through a protein. Introduction of a non-resonant VIS pulse at the end of the IR part of the experiment allows to selectively up-convert the infrared signal of interfacial molecules to the visible spectral range by sum frequency generation. In this way, femtosecond interfacial 2D-IR spectroscopy can be implemented, achieving sub-monolayer sensitivity. (author)

MODIS/Aqua Calibrated Radiances 5-Min L1B Swath 250m - NRT

Data.gov (United States)

National Aeronautics and Space Administration — The 250 meter MODIS Level 1B Near Real Time (NRT) data set contains calibrated and geolocated at-aperture radiances for 2 discrete bands located in the 0.62 to 0.88...

The 2003 edition of geisa: a spectroscopic database system for the second generation vertical sounders radiance simulation

Science.gov (United States)

Jacquinet-Husson, N.; Lmd Team

The GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) computer accessible database system, in its former 1997 and 2001 versions, has been updated in 2003 (GEISA-03). It is developed by the ARA (Atmospheric Radiation Analysis) group at LMD (Laboratoire de Météorologie Dynamique, France) since 1974. This early effort implemented the so-called `` line-by-line and layer-by-layer '' approach for forward radiative transfer modelling action. The GEISA 2003 system comprises three databases with their associated management softwares: a database of spectroscopic parameters required to describe adequately the individual spectral lines belonging to 42 molecules (96 isotopic species) and located in a spectral range from the microwave to the limit of the visible. The featured molecules are of interest in studies of the terrestrial as well as the other planetary atmospheres, especially those of the Giant Planets. a database of absorption cross-sections of molecules such as chlorofluorocarbons which exhibit unresolvable spectra. a database of refractive indices of basic atmospheric aerosol components. Illustrations will be given of GEISA-03, data archiving method, contents, management softwares and Web access facilities at: http://ara.lmd.polytechnique.fr The performance of instruments like AIRS (Atmospheric Infrared Sounder; http://www-airs.jpl.nasa.gov) in the USA, and IASI (Infrared Atmospheric Sounding Interferometer; http://smsc.cnes.fr/IASI/index.htm) in Europe, which have a better vertical resolution and accuracy, compared to the presently existing satellite infrared vertical sounders, is directly related to the quality of the spectroscopic parameters of the optically active gases, since these are essential input in the forward models used to simulate recorded radiance spectra. For these upcoming atmospheric sounders, the so-called GEISA/IASI sub-database system has been elaborated

Alkoholio ir tabako pasiūlos ir paklausos teisinio reguliavimo raida Lietuvos Respublikoje: problemos ir sprendimai

OpenAIRE

Mockevičius, Arminas

2014-01-01

Viešosios teisės magistro studijų programos studento Armino Mockevičiaus buvo parašytas magistro baigiamasis darbas „Alkoholio ir tabako pasiūlos ir paklausos teisinio reguliavimo raida Lietuvos Respublikoje: problemos ir sprendimai“. Šis darbas parašytas Vilniuje, 2014 metais, Mykolo Romerio universiteto Teisės fakulteto Konstitucinės ir administracinės teisės institute, vadovaujant dr. Gintautui Vilkeliui, apimtis 98 p. Darbo tikslas yra atskleisti alkoholio ir tabako pasiūlos ir paklau...

Spectral analysis of the structure of ultradispersed diamonds

Science.gov (United States)

Uglov, V. V.; Shimanski, V. I.; Rusalsky, D. P.; Samtsov, M. P.

2008-07-01

The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles changes during the treatment.

A Method of Retrieving BRDF from Surface-Reflected Radiance Using Decoupling of Atmospheric Radiative Transfer and Surface Reflection

Directory of Open Access Journals (Sweden)

Alexander Radkevich

2018-04-01

Full Text Available Bi-directional reflection distribution function (BRDF defines anisotropy of the surface reflection. It is required to specify the boundary condition for radiative transfer (RT modeling used in aerosol retrievals, cloud retrievals, atmospheric modeling, and other applications. Ground based measurements of reflected radiance draw increasing attention as a source of information about anisotropy of surface reflection. Derivation of BRDF from surface radiance requires atmospheric correction. This study develops a new method of retrieving BRDF on its whole domain, making it immediately suitable for further atmospheric RT modeling applications. The method is based on the integral equation relating surface-reflected radiance, BRDF, and solutions of two auxiliary atmosphere-only RT problems. The method requires kernel-based BRDF. The weights of the kernels are obtained with a quickly converging iterative procedure. RT modeling has to be done only one time before the start of iterative process.

Optical properties of reduced graphene oxide and CuFe2O4 composites in the IR region

Science.gov (United States)

Ma, De-yue; Li, Xiao-xia; Guo, Yu-xiang; Zeng, Yu-run

2018-01-01

The complex refractive index of reduced graphene oxide and CuFe2O4 composites prepared by hydrothermal method was calculated using infrared Micro-reflective spectra and K-K relation, and the calculation errors were analyzed according to its IR transmission and spectral reflectivity calculated by Fresnel formula. And then normal emissivity of the composite in IR atmospheric window was calculated by means of Fresnel formula and modified refraction angle formula. The calculation accuracy was verified by comparing measured normal total emissivity with the calculated one. The results show that complex refractive index and normal emissivity calculated by the formulas have a high accuracy. It has been found that the composite has a good absorption and radiation characteristics in IR atmospheric window and a strong scattering ability in middle IR region by analyzing its extinction, absorption and radiation properties in IR region. Therefore, it may be used as IR absorption, extinction and radiation materials in some special fields.

Methods of total spectral radiant flux realization at VNIIOFI

Science.gov (United States)

Ivashin, Evgeniy; Lalek, Jan; Rybczyński, Andrzej; Ogarev, Sergey; Khlevnoy, Boris; Dobroserdov, Dmitry; Sapritsky, Victor

2018-02-01

VNIIOFI carries out works on realization of independent methods for realization of the total spectral radiant flux (TSRF) of incoherent optical radiation sources - reference high-temperature blackbodies (BB), halogen lamps, and LED with quasi-Lambert spatial distribution of radiance. The paper describes three schemes for measuring facilities using photometers, spectroradiometers and computer-controlled high class goniometer. The paper describes different approaches for TSRF realization at the VNIIOFI National radiometric standard on the basis of high-temperature BB and LED sources, and gonio-spectroradiometer. Further, they are planned to be compared, and the use of fixed-point cells (in particular, based on the high-temperature δ(MoC)-C metal-carbon eutectic with a phase transition temperature of 2583 °C corresponding to the metrological optical “source-A”) as an option instead of the BB is considered in order to enhance calibration accuracy.

Spectral and thermal investigation of tetrabenzoylacetonatobenzoylacetonediuranyl

International Nuclear Information System (INIS)

Kostyuk, N.N.; Dik, T.A.; Klavsut', G.N.; Umrejko, D.S.

1989-01-01

Uranium(6) compound with benzoylacetone (NBA) of [(UO 2 ) 2 (NBA)(BA) 4 ] composition was prepared by the method of electrochemical synthesis in oxidizing medium. Spectral and thermal investigation (data of IR, Raman spectra, TG, DTA) was conducted to show that four NBA molecules entered the compound as acidoligands and one NBA molecule (being a bridge) - as neutral ligand in keto-form. Mechanism of thermal decomposition was suggested and kinetic parameters of thermolysis of examined substance were calculated

Reflectance spectral analyses for the assessment of environmental pollution in the geothermal site of Mt. Amiata (Italy)

Science.gov (United States)

Manzo, Ciro; Salvini, Riccardo; Guastaldi, Enrico; Nicolardi, Valentina; Protano, Giuseppe

2013-11-01

We studied the environmental impact of geothermal activities in the Mt. Amiata area, using on-site spectral analyses of various ecological components. Analytical techniques were based on the study of the “red-edge”, which represents the spectral feature of the reflectance spectra defined between red and infrared wavelengths (λ) within the range 670-780 nm. Since in the study area the geothermal exploitation causes the drifting of contaminants such as Hg, Sb, S, B, As and H2S (hydrogen sulfide) from power plants, the spectral response of vegetation and lichens depends on their distance from the power stations, and also on the exposed surface, material type and other physical parameters. In the present research, the spectral radiance of targets was measured in the field using an Analytical Spectral Device (ASD) Field-Spec™FR portable radiometer. Spectral measurements were made on vegetation and lichen samples located near to and far from geothermal areas and potential pollution sources (e.g., power plants), with the aim of spatially defining their environmental impact. Observations for vegetation and lichens showed correlation with laboratory chemical analyses when these organisms were under stress conditions. The evaluation of relationships was carried out using several statistical approaches, which allowed to identify methods for identifying contamination indicators for plants and lichens in polluted areas. Results show that the adopted spectral indices are sensitive to environmental pollution and their responses spatialstatically correlated to chemical and ecophysiological analyses within a notable distance.

MODIS/Aqua Raw Radiances in Counts 5-Min L1A Swath V006

Data.gov (United States)

National Aeronautics and Space Administration — The MODIS/Aqua Raw Radiances in Counts 5-Min L1A Swath (MYD01) product contains reformatted and packaged raw instrument data. MODIS instrument data, in packetized...

SU-E-T-470: Beam Performance of the Radiance 330 Proton Therapy System

International Nuclear Information System (INIS)

Nazaryan, H; Nazaryan, V; Wang, F; Flanz, J; Alexandrov, V

2014-01-01

Purpose: The ProTom Radiance 330 proton radiotherapy system is a fully functional, compact proton radiotherapy system that provides advanced proton delivery capabilities. It supports three-dimensional beam scanning with energy and intensity modulation. A series of measurements have been conducted to characterize the beam performance of the first installation of the system at the McLaren Proton Therapy Center in Flint, Michigan. These measurements were part of the technical commissioning of the system. Select measurements and results are presented. Methods: The Radiance 330 proton beam energy range is 70–250 MeV for treatment, and up to 330 MeV for proton tomography and radiography. Its 3-D scanning capability, together with a small beam emittance and momentum spread, provides a highly efficient beam delivery. During the technical commissioning, treatment plans were created to deliver uniform maps at various energies to perform Gamma Index analysis. EBT3 Gafchromic films were irradiated using the Planned irradiation maps. Bragg Peak chamber was used to test the dynamic range during a scan in one layer for high (250 MeV) and Low (70 MeV) energies. The maximum and minimum range, range adjustment and modulation, distal dose falloff (80%–20%), pencil beam spot size, spot placement accuracy were also measured. The accuracy testing included acquiring images, image registration, receiving correction vectors and applying the corrections to the robotic patient positioner. Results: Gamma Index analysis of the Treatment Planning System (TPS) data vs. Measured data showed more than 90% of points within (3%, 3mm) for the maps created by the TPS. At Isocenter Beam Size (One sigma) < 3mm at highest energy (250 MeV) in air. Beam delivery was within 0.6 mm of the intended target at the entrance and the exit of the beam, through the phantom. Conclusion: The Radiance 330 Beam Performance Measurements have confirmed that the system operates as designed with excellent clinical

SU-E-T-470: Beam Performance of the Radiance 330 Proton Therapy System

Energy Technology Data Exchange (ETDEWEB)

Nazaryan, H; Nazaryan, V; Wang, F [ProTom International, Inc., Flower Mound, TX (United States); Flanz, J [Massachusetts General Hospital, Boston, MA (United States); Alexandrov, V [ZAO ProTom, Protvino, Moscow region (Russian Federation)

2014-06-01

Purpose: The ProTom Radiance 330 proton radiotherapy system is a fully functional, compact proton radiotherapy system that provides advanced proton delivery capabilities. It supports three-dimensional beam scanning with energy and intensity modulation. A series of measurements have been conducted to characterize the beam performance of the first installation of the system at the McLaren Proton Therapy Center in Flint, Michigan. These measurements were part of the technical commissioning of the system. Select measurements and results are presented. Methods: The Radiance 330 proton beam energy range is 70–250 MeV for treatment, and up to 330 MeV for proton tomography and radiography. Its 3-D scanning capability, together with a small beam emittance and momentum spread, provides a highly efficient beam delivery. During the technical commissioning, treatment plans were created to deliver uniform maps at various energies to perform Gamma Index analysis. EBT3 Gafchromic films were irradiated using the Planned irradiation maps. Bragg Peak chamber was used to test the dynamic range during a scan in one layer for high (250 MeV) and Low (70 MeV) energies. The maximum and minimum range, range adjustment and modulation, distal dose falloff (80%–20%), pencil beam spot size, spot placement accuracy were also measured. The accuracy testing included acquiring images, image registration, receiving correction vectors and applying the corrections to the robotic patient positioner. Results: Gamma Index analysis of the Treatment Planning System (TPS) data vs. Measured data showed more than 90% of points within (3%, 3mm) for the maps created by the TPS. At Isocenter Beam Size (One sigma) < 3mm at highest energy (250 MeV) in air. Beam delivery was within 0.6 mm of the intended target at the entrance and the exit of the beam, through the phantom. Conclusion: The Radiance 330 Beam Performance Measurements have confirmed that the system operates as designed with excellent clinical

Fourier Transform Infrared Spectroscopy (FT-IR) and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Developmental Cotton Fibers.

Science.gov (United States)

Liu, Yongliang; Kim, Hee-Jin

2017-06-22

With cotton fiber growth or maturation, cellulose content in cotton fibers markedly increases. Traditional chemical methods have been developed to determine cellulose content, but it is time-consuming and labor-intensive, mostly owing to the slow hydrolysis process of fiber cellulose components. As one approach, the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy technique has also been utilized to monitor cotton cellulose formation, by implementing various spectral interpretation strategies of both multivariate principal component analysis (PCA) and 1-, 2- or 3-band/-variable intensity or intensity ratios. The main objective of this study was to compare the correlations between cellulose content determined by chemical analysis and ATR FT-IR spectral indices acquired by the reported procedures, among developmental Texas Marker-1 (TM-1) and immature fiber ( im ) mutant cotton fibers. It was observed that the R value, CI IR , and the integrated intensity of the 895 cm -1 band exhibited strong and linear relationships with cellulose content. The results have demonstrated the suitability and utility of ATR FT-IR spectroscopy, combined with a simple algorithm analysis, in assessing cotton fiber cellulose content, maturity, and crystallinity in a manner which is rapid, routine, and non-destructive.

Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

Energy Technology Data Exchange (ETDEWEB)

Younkin, K; Long, CN

2003-11-01

Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km V005

Data.gov (United States)

National Aeronautics and Space Administration — The MODIS Level 1B data set contains calibrated and geolocated at-aperture radiances for 36 discrete bands located in the 0.4 to 14.4 micron region of...

Instrument development for atmospheric radiation measurement (ARM): Status of the Atmospheric Emitted Radiance Interferometer - extended Resolution (AERI-X), the Solar Radiance Transmission Interferometer (SORTI), and the Absolute Solar Transmission Inferometer (ASTI)

Energy Technology Data Exchange (ETDEWEB)

Murcray, F.; Stephen, T.; Kosters, J. [Univ. of Denver, CO (United States)

1996-04-01

This paper describes three instruments currently under developemnt for the Atmospheric Radiation Measurement (ARM) Program at the University of Denver: the AERI-X (Atmospheric Emitted Radiance Interferometer-Extended Resolution) and the SORTI (Solar R adiance Transmission Interferometer), and ASTI (Absolute Solar transmission Interferometer).

Optimization of silicon waveguides for gas detection application at mid-IR wavelengths

Science.gov (United States)

Butt, M. A.; Kozlova, E. S.

2018-04-01

There are several trace gases such as N2O, CO, CO2, NO, H2O, NO2, NH3, CH4 etc. which have their absorption peaks in Mid-IR spectrum These gases strongly absorb in the mid-IR > 2.5 μm spectral region due to their fundamental rotational and vibrational transitions. In this work, we modelled and optimized three different kinds of waveguides such as rib, strip and slot based on silicon platform to obtain maximum evanescent field ratio. These waveguides are designed at 3.39 μm and 4.67 μm which correspond to the absorption line of methane (CH4) and carbon monoxide (CO) respectively.

Solitonic supercontinuum of femtosecond mid-IR pulses in W-type index tellurite fibers with two zero dispersion wavelengths

Directory of Open Access Journals (Sweden)

S. Kedenburg

2016-11-01

Full Text Available We present a detailed experimental parameter study on mid-IR supercontinuum generation in W-type index tellurite fibers, which reveals how the core diameter, pump wavelength, fiber length, and pump power dramatically influence the spectral broadening. As pump source, we use femtosecond mid-IR pulses from a post-amplified optical parametric oscillator tunable between 1.7 μm and 4.1 μm at 43 MHz repetition rate. We are able to generate red-shifted dispersive waves up to a wavelength of 5.1 μm by pumping a tellurite fiber in the anomalous dispersion regime between its two zero dispersion wavelengths. Distinctive soliton dynamics can be identified as the main broadening mechanism resulting in a maximum spectral width of over 2000 nm with output powers of up to 160 mW. We experimentally demonstrated that efficient spectral broadening with considerably improved power proportion in the important first atmospheric transmission window between 3 and 5 μm can be achieved in robust W-type tellurite fibers pumped at long wavelengths by ultra-fast lasers.

Temporal and spectral studies of high-order harmonics generated by polarization-modulated infrared fields

International Nuclear Information System (INIS)

Sola, I. J.; Zaier, A.; Cormier, E.; Mevel, E.; Constant, E.; Lopez-Martens, R.; Johnsson, P.; Varju, K.; Mauritsson, J.; L'Huillier, A.; Strelkov, V.

2006-01-01

The temporal confinement of high harmonic generation (HHG) via modulation of the polarization of the fundamental pulse is studied in both temporal and spectral domains. In the temporal domain, a collinear cross-correlation setup using a 40 fs IR pump for the HHG and a 9 fs IR pulse to probe the generated emission is used to measure the XUV pulse duration. The observed temporal confinement is found to be consistent with theoretical predictions. An increased confinement is observed when a 9 fs pulse is used to generate the harmonics. An important spectral broadening, including a continuum background, is also measured. Theoretical calculations show that with 10 fs driving pulses, either one or two main attosecond pulses are created depending on the value of the carrier envelope phase

Spectral dimension of the universe in quantum gravity at a lifshitz point.

Science.gov (United States)

Horava, Petr

2009-04-24

We extend the definition of "spectral dimension" d_{s} (usually defined for fractal and lattice geometries) to theories in spacetimes with anisotropic scaling. We show that in gravity with dynamical critical exponent z in D+1 dimensions, the spectral dimension of spacetime is d_{s}=1+D/z. In the case of gravity in 3+1 dimensions with z=3 in the UV which flows to z=1 in the IR, the spectral dimension changes from d_{s}=4 at large scales to d_{s}=2 at short distances. Remarkably, this is the behavior found numerically by Ambjørn et al. in their causal dynamical triangulations approach to quantum gravity.

Joint Navy and Air Force Infrared Sensor Stimulator (IRSS) Program for Installed Systems Test Facilities (ISTFs)

National Research Council Canada - National Science Library

Joyner, Tom

1998-01-01

...) sensors undergoing integrated developmental and operational testing. IRSS generates digital IR scenes in real time to provide a realistic portrayal of IR scene radiance as viewed by and IR system under test in a threat engagement scenario...

Providing radiometric traceability for the calibration home base of DLR by PTB

Energy Technology Data Exchange (ETDEWEB)

Taubert, D. R.; Hollandt, J.; Sperfeld, P.; Pape, S.; Hoepe, A.; Hauer, K.-O. [Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin, 10587 Berlin (Germany); Gege, P.; Schwarzmaier, T.; Lenhard, K.; Baumgartner, A. [Deutsches Zentrum fuer Luft- und Raumfahrt, Institut fuer Methodik der Fernerkundung, 82234 Oberpfaffenhofen (Germany)

2013-05-10

A dedicated calibration technique was applied for the calibration of the spectral radiance transfer standard (RASTA) of the German Aerospace Center (DLR) at the Physikalisch-Technische Bundesanstalt (PTB), consisting of two independent but complementing calibration procedures to provide redundancy and smallest possible calibration uncertainties. Procedure I included two calibration steps: In a first step the optical radiation source of RASTA, an FEL lamp, was calibrated in terms of its spectral irradiance E{sub {lambda}}({lambda}) in the wavelength range from 350 nm to 2400 nm using the PTB Spectral Irradiance Calibration Equipment (SPICE), while in a second step the spectral radiance factor {beta}{sub 0 Degree-Sign :45 Degree-Sign }({lambda}) of the RASTA reflection standard was calibrated in a 0 Degree-Sign :45 Degree-Sign -viewing geometry in the wavelength range from 350 nm to 1700 nm at the robot-based gonioreflectometer facility of PTB. The achieved relative standard uncertainties (k= 1) range from 0.6 % to 3.2 % and 0.1 % to 0.6 % respectively. Procedure II was completely independent from procedure I and allowed to cover the entire spectral range of RASTA from 350 nm to 2500 nm. In the second procedure, the 0 Degree-Sign :45 Degree-Sign -viewing geometry spectral radiance L{sub {lambda},0 Degree-Sign :45 Degree-Sign }({lambda}) of RASTA was directly calibrated at the Spectral Radiance Comparator Facility (SRCF) of PTB. The relative uncertainties for this calibration procedure range from 0.8 % in the visible up to 7.5 % at 2500 nm (k= 1). In the overlapping spectral range of both calibration procedures the calculated spectral radiance L{sub {lambda},0 Degree-Sign :45 Degree-Sign ,calc}({lambda}) from procedure I is in good agreement with the direct measurement of procedure II, i.e. well within the combined expanded uncertainties (k= 2) of both procedures.

An assessment of radiance in Landsat TM middle and thermal infrared wavebands for the detection of tropical forest regeneration

International Nuclear Information System (INIS)

Boyd, D.S.; Foody, G.M.; Curran, P.J.; Lucas, R.M.; Honzak, M.

1996-01-01

It has been postulated that tropical forests regenerating after deforestation constitute an unmeasured terrestrial sink of atmospheric carbon, and that the strength of this sink is a function of regeneration stage. Such regeneration stages can be characterized by biophysical properties, such as leaf and wood biomass, which influence the radiance emitted and/or reflected from the forest canopy. Remotely sensed data can therefore be used to estimate these biophysical properties and thereby determine the forest regenerative stage. Studies conducted on temperate forests have related biophysical properties successfully with red and near-infrared radiance, particularly within the Normalized Difference Vegetation Index (NDVI). However, only weak correlations have generally been observed for tropical forests and it is suggested here that the relationship between forest biophysical properties and middle and thermal infrared radiance may be stronger than that between those properties and visible and near-infrared radiance.An assessment of Landsat Thematic Mapper (TM) data revealed that radiance acquired in middle and thermal infrared wavebands contained significant information for the detection of regeneration stages in Amazonian tropical forests. It was demonstrated that tropical forest regeneration stages were most separable using middle infrared and thermal infrared wavebands and that the correlation with regeneration stage was stronger with middle infrared, thermal infrared or combinations of these wavebands than they were with visible, near infrared or combinations of these wavebands. For example, correlation coefficients increased from — 0·26 (insignificant at 95 per cent confidence level) when using the NDVI, to up to 0·93 (significant at 99 per cent confidence level) for a vegetation index containing data acquired in the middle and thermal infrared wavebands. These results point to the value of using data acquired in middle and thermal infrared wavebands for the

Near diffraction limited mid-IR spectromicroscopy using frequency upconversion

DEFF Research Database (Denmark)

Sanders, Nicolai Højer; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter

2014-01-01

morphological and spectral imaging. Recent developments in nonlinear frequency upconversion, have demonstrated the potential to perform both imaging and spectroscopy in the mid-IR range at unparalleled low levels of illumination, the low upconversion detector noise being orders of magnitude below competing...... technologies. With these applications in mind, we have incorporated microscopy optics into an image upconversion system, achieving near diffraction limited spatial resolution in the 3 μm range. Spectroscopic information is further acquired by appropriate control of the phase match condition of the upconversion...

An improved synthesis, spectroscopic (FT-IR, NMR) study and DFT computational analysis (IR, NMR, UV-Vis, MEP diagrams, NBO, NLO, FMO) of the 1,5-methanoazocino[4,3-b]indole core structure

Science.gov (United States)

Uludağ, Nesimi; Serdaroğlu, Goncagül

2018-03-01

This study examines the synthesis of azocino[4,3-b]indole structure, which constitutes the tetracyclic framework of uleine, dasycarpidoneand tubifolidineas well as ABDE substructure of the strychnosalkaloid family. It has been synthesized by Fischer indolization of 2 and through the cylization of 4 by 2,3-dichlor-5-6-dicyanobenzoquinone (DDQ). 1H and 1C NMR chemical shifts have been predicted with GIAO approach and the calculated chemical shifts show very good agreement with observed shifts. FT-IR spectroscopy is important for the analysis of functional groups of synthesized compounds and we also supported FT-IR vibrational analysis with computational IR analysis. The vibrational spectral analysis was performed at B3LYP level of the theory in both the gas and the water phases and it was compared with the observed IR values for the important functional groups. The DFT calculations have been conducted to determine the most stable structure of the 1,2,3,4,5,6,7-Hexahydro-1,5-methanoazocino [4,3-b] indole (5). The Frontier Molecular Orbital Analysis, quantum chemical parameters, physicochemical properties have been predicted by using the same theory of level in both gas phase and the water phase, at 631 + g** and 6311++g** basis sets. TD- DFT calculations have been performed to predict the UV- Vis spectral analysis for this synthesized molecule. The Natural Bond Orbital (NBO) analysis have been performed at B3LYP level of theory to elucidate the intra-molecular interactions such as electron delocalization and conjugative interactions. NLO calculations were conducted to obtain the electric dipole moment and polarizability of the title compound.

A neural network method to correct bidirectional effects in water-leaving radiance

Science.gov (United States)

Fan, Yongzhen; Li, Wei; Voss, Kenneth J.; Gatebe, Charles K.; Stamnes, Knut

2017-02-01

The standard method to convert the measured water-leaving radiances from the observation direction to the nadir direction developed by Morel and coworkers requires knowledge of the chlorophyll concentration (CHL). Also, the standard method was developed for open ocean water, which makes it unsuitable for turbid coastal waters. We introduce a neural network method to convert the water-leaving radiance (or the corresponding remote sensing reflectance) from the observation direction to the nadir direction. This method does not require any prior knowledge of the water constituents or the inherent optical properties (IOPs). This method is fast, accurate and can be easily adapted to different remote sensing instruments. Validation using NuRADS measurements in different types of water shows that this method is suitable for both open ocean and coastal waters. In open ocean or chlorophyll-dominated waters, our neural network method produces corrections similar to those of the standard method. In turbid coastal waters, especially sediment-dominated waters, a significant improvement was obtained compared to the standard method.

MODIS/Terra Calibrated Radiances 5-Min L1B Swath 500m V005

Data.gov (United States)

National Aeronautics and Space Administration — The 500 meter MODIS Level 1B data set contains calibrated and geolocated at-aperture radiances for 7 discrete bands located in the 0.45 to 2.20 micron region of the...

MODIS/Terra Calibrated Radiances 5-Min L1B Swath 250m V005

Data.gov (United States)

National Aeronautics and Space Administration — The 250 meter MODIS Level 1B data set contains calibrated and geolocated at-aperture radiances for 2 discrete bands located in the 0.62 to 0.88 micron region of the...

Quality assurance of the Brewer spectral UV measurements in Finland

Directory of Open Access Journals (Sweden)

K. Lakkala

2008-06-01

Full Text Available The quality assurance of the two Brewer spectrophotometers of the Finnish Meteorological Institute is discussed in this paper. The complete data processing chain from raw signal to high quality spectra is presented. The quality assurance includes daily maintenance, laboratory characterizations, calculation of long-term spectral responsivity, data processing and quality assessment. The cosine correction of the measurements is based on a new method, and is included in the data processing software. The results showed that the actual cosine correction factor of the two Finnish Brewers can vary between 1.08–1.13 and 1.08–1.12, respectively, depending on the sky radiance distribution and wavelength. The temperature characterization showed a linear temperature dependence between the instruments' internal temperature and the photon counts per cycle, and a temperature correction was used for correcting the measurements. The long-term spectral responsivity was calculated using the time series of several lamps using two slightly different methods. The long-term spectral responsivity was scaled to the irradiance scale of the Helsinki University of Technology (HUT for the whole of the measurement time-periods 1990–2006 and 1995–2006 for Sodankylä and Jokioinen, respectively. Both Brewers have participated in many international spectroradiometer comparisons, and have shown good stability. The differences between the Brewers and the portable reference spectroradiometer QASUME have been within 5% during 2002–2007.

Spectral dependence of the main parameters of ITE silicon avalanche photodiodes

Science.gov (United States)

Wegrzecka, Iwona; Grynglas, Maria; Wegrzecki, Maciej

2001-08-01

New applications for avalanche photodiodes (APDs) as in systems using visible radiation, have prompted the need for the evaluation of detection properties of ITE APDs in the 400 divided by 700 nm spectral range. The paper presents the method and result of studies on the spectral dependence of the gain, dark and noise currents, sensitivity and excess noise factor of ITE APDs. The studies have shown that ITE APDs optimized for the near IR radiation can be effectively applied in the detection of radiation above the 500 nm wavelength.

Enhanced spectral emissivity of CeO{sub 2} coating with cauliflower-like microstructure

Energy Technology Data Exchange (ETDEWEB)

Huang Jianping [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Li Yibin, E-mail: liyibin@hit.edu.cn [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); He Xiaodong; Song Guangping [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Fan Chenglei [Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, 150001 Harbin (China); Sun Yue [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Fei Weidong [School of Materials Science and Engineering, Harbin Institute of Technology, 150001 Harbin (China); Du Shanyi [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Cauliflower-like microstructured CeO{sub 2} coating is prepared on Ni based substrate. Black-Right-Pointing-Pointer The infrared emissive property at high temperature is investigated. Black-Right-Pointing-Pointer Rough CeO{sub 2} coating shows high emissivity, that is, 0.9 at 873 K and 0.87 at 1073 K. Black-Right-Pointing-Pointer The emissivity enhancement mechanisms for the rough CeO{sub 2} coating are discussed. - Abstract: Cerium dioxide is a transparent oxide with high refractive index (from 1.6 to 2.5 at 633 nm) in the visible and near-IR spectral regions. However, little attention has been paid to its optical property in mid-IR (2.5-25 {mu}m). Here we report that the cauliflower-like microstructured CeO{sub 2} coating deposited by electron beam physical vapor deposition technique shows high emissivity up to 0.9 at 873 K in the mid-IR spectral region. The high emissivity is attributed to the coupling between free propagating waves and space-variant polarizations caused by the cauliflower-like microstructure. This high emissivity coating shows a potential application in high temperature components.

Evaluating Surgical Margins with Optical Spectroscopy and Spectral Imaging Following Breast Cancer Resection

Science.gov (United States)

2009-08-01

Raman spectral features of hydroxyapatite crystals (found in breast calcifications) through overlying lean chicken breast tissue [18]. Thus, the...Raman signature of bone through several mm of soft tissue [3-5]. It has also been used to detect the Ram an spectral features of hydroxyapatite ...all f eaturing in- line f iltering at the ir tips (Em vision). All seve n f ibers we re bin ned a fter a sing le 3 se cond acquisition, and these

Optical radiation measurements II; Proceedings of the Meeting, Orlando, FL, Mar. 27, 28, 1989

Science.gov (United States)

Palmer, James M.

1989-09-01

The present conference discusses topics in the characterization of imaging radiometers, laboratory instrumentation, field and spacecraft instrumentation, and quantum and thermal standard detectors. Attention is given to UV radiometric imaging, dual-color radiometer imagery, a novel diode-array radiometer, a novel reference spectrophotometer, radiance calibration of spherical integrators, instrumentation for measurement of spectral goniometric reflectance, and a real-time IR background discrimination radiometer. Also discussed are a multichannel radiometer for atmosphere optical property measurements, the UV spectroradiometric output of a turbojet, characterizations of the Earth Radiation Budget Experiment scanning radiometers, total-radiation thermometry, future directions in Si photodiode self-calibration, and radiometric quality Ge photodiodes.

Mid IR-fiber spectroscopy in the 2-17μm range

Science.gov (United States)

Artyushenko, Viatcheslav G.; Bocharnikov, A.; Colquhoun, Gary; Leach, Clive A.; Lobachov, Vladimir; Pirogova, Lyudmila; Sakharova, Tatjana; Savitskij, Dmitrij; Ezhevskaya, Tatjana; Bublikov, Alexandr

2007-10-01

The latest development in IR-fibre optics enables us to expand the spectral range of process spectroscopy from 2μm out to 17μm (5000 to 600cm-1) i.e. into the most informative "finger-print" part of the spectrum. Mid-IR wavelength ranges from 2 to 6-10μm may be covered by Chalcogenide IR-glass CIR-fibres while Polycrystalline PIR-fibres made of Silver Halides solid solutions transmit 4-17 μm wavelength radiation. PIR-fibre immersion ATR probes and Transmission/Reflection probes had been manufactured and successfully tested with different FTIR spectrometers in the field of remote spectroscopy for forensic substances identification, chemical reaction control, and monitoring of exhaust or exhalation gases. Using these techniques no sample preparation is necessary for fibre probes to measure evanescent, reflection and transmission spectra, in situ and in real time. QCL spectrometer may be used as a portable device for multispectral gas analysis at 1ppb level of detectivity for various applications in environmental pollution monitoring.

Development of multi-sensor global cloud and radiance composites for earth radiation budget monitoring from DSCOVR

Science.gov (United States)

Khlopenkov, Konstantin; Duda, David; Thieman, Mandana; Minnis, Patrick; Su, Wenying; Bedka, Kristopher

2017-10-01

The Deep Space Climate Observatory (DSCOVR) enables analysis of the daytime Earth radiation budget via the onboard Earth Polychromatic Imaging Camera (EPIC) and National Institute of Standards and Technology Advanced Radiometer (NISTAR). Radiance observations and cloud property retrievals from low earth orbit and geostationary satellite imagers have to be co-located with EPIC pixels to provide scene identification in order to select anisotropic directional models needed to calculate shortwave and longwave fluxes. A new algorithm is proposed for optimal merging of selected radiances and cloud properties derived from multiple satellite imagers to obtain seamless global hourly composites at 5-km resolution. An aggregated rating is employed to incorporate several factors and to select the best observation at the time nearest to the EPIC measurement. Spatial accuracy is improved using inverse mapping with gradient search during reprojection and bicubic interpolation for pixel resampling. The composite data are subsequently remapped into EPIC-view domain by convolving composite pixels with the EPIC point spread function defined with a half-pixel accuracy. PSF-weighted average radiances and cloud properties are computed separately for each cloud phase. The algorithm has demonstrated contiguous global coverage for any requested time of day with a temporal lag of under 2 hours in over 95% of the globe.

New Style of Volcanic Eruption Activity Identified in Galileo NIMS data at Marduk Fluctus, Io

Science.gov (United States)

Davies, A. G.; Davies, R. L.; Veeder, G. J.; de Kleer, K.; De Pater, I.; Matson, D.

2017-12-01

Analysis of observations of Marduk Fluctus, Io, by the Galileo Near Infrared Mapping Spectrometer (NIMS) reveals a style of volcanic activity not previously seen on Io - a very short-duration, highly-changeable, powerful thermal event, similar to what might be expected from a strombolian-like explosion. Marduk Fluctus is a persistent active volcano characterised by ≈3600 km2 of silicate flows [1]. Between 1996 and 2001, NIMS obtained 44 observations of Marduk Fluctus at a wide variety of spatial and spectral resolutions. Six observations were obtained during Galileo orbit E4, with five nighttime observations obtained on 1996 Dec 19 in the space of less than three hours. Three of these observations were each separated by one minute. Compared to the previous observation obtained a few hours earlier, the first two of these three observations show an order of magnitude increase in spectral radiance (corrected for emission angle). Spectral radiance then dropped back to the background level one minute later. The emission angles for these five E4 observations are large (>70°), but even without the emission angle radiance correction the spike in activity is still a factor of five larger than the pre- and post-spike radiances. The NIMS spectrum of the central observation shows a shift in peak of thermal emission to short wavelengths characteristic of the exposure of a large area of incandescent lava. The rapid increase and decrease in activity suggests an equally rapid physical process, the most likely being a large strombolian explosion that generated small clasts that cooled rapidly. The presence of such events provide an additional volcanic process that can be imaged with the intent of determining lava composition from eruption temperature, an important constraint on internal composition and state. For this particular eruption type, eruption temperature can be constrained if non-saturated, multiple-wavelength IR observations are obtained simultaneously and with very

Ultra-Low-Noise Sub-mm/Far-IR Detectors for Space-Based Telescopes

Science.gov (United States)

Rostem, Karwan

The sub-mm and Far-IR spectrum is rich with information from a wide range of astrophysical sources, including exoplanet atmospheres and galaxies at the peak star formation. In the 10-400 μm range, the spectral lines of important chemical species such H2O, HD, and [OI] can be used to map the formation and evolution of planetary systems. Dust emission in this spectral range is also an important tool for characterizing the morphology of debris disks and interstellar magnetic fields. At larger scales, accessing the formation and distribution of luminous Far-IR and sub-mm galaxies is essential to understanding star formation triggers, as well as the last stages of reionization at z 6. Detector technology is essential to realizing the full science potential of a next-generation Far-IR space telescope (Far-IR Surveyor). The technology gap in large-format, low-noise and ultra-low-noise Far-IR direct detectors is specifically highlighted by NASA's Cosmic Origins Program, and prioritized for development now to enable a flagship mission such as the Far-IR Surveyor that will address the key Cosmic Origins science questions of the next two decades. The detector requirements for a mid-resolution spectrometer are as follows: (1) Highly sensitive detectors with performance approaching 10^-19 - 10^-20 WHz 1/2 for background- limited operation in telescopes with cold optics. (2) Detector time constant in the sub- millisecond range. (3) Scalable architecture to a kilo pixel array with uniform detector characteristics. (4) Compatibility with space operation in the presence of particle radiation. We propose phononic crystals to meet the requirements of ultra-low-noise thermal detectors. By design, a phononic crystal exhibits phonon bandgaps where heat transport is forbidden. The size and location of the bandgaps depend on the elastic properties of the dielectric and the geometry of the phononic unit cell. A wide-bandwidth low-pass thermal filter with a cut-off frequency of 1.5 GHz and

IASI hyperspectral radiances in the NCMRWF 4D-VAR assimilation system: OSE

Science.gov (United States)

Sharma, Priti; Indira Rani, S.; Mallick, Swapan; Srinivas, D.; George, John P.; Dasgupta, Munmun

2016-04-01

Accuracy of global NWP depends more on the contribution of satellite data than the surface based observations. This is achieved through the better usage of satellite data within the data assimilation system. Efforts are going on at NCMRWF to add more and more satellite data in the assimilation system both from Indian and international satellites in geostationary and polar orbits. Impact of the new dataset is assessed through Observation System Experiments (OSEs), through which the impact of the data is evaluated comparing the forecast output with that of a control run. This paper discusses one such OSEs with Infrared Atmospheric Sounder Interferometer (IASI) onboard MetOp-A and B. IASI is the main payload instrument for the purpose of supporting NWP. IASI provides information on the vertical structure of the atmospheric temperature and humidity with an accuracy of 1K and a vertical resolution of 1 km, which is necessary to improve NWP. IASI measures the radiance emitted from the Earth in 8641 channels, covering the spectral interval 645-2760 cm-1. The high volume data resulting from IASI presents many challenges, particularly in the area of assimilation. Out of these 8641 channels, 314 channels are selected depending on the relevance of information in each channel to assimilate in the NCMRWF 4D-VAR assimilation system. Studies show that the use of IASI data in NWP accounts for 40% of the impact of all satellite observations in the NWP forecasts, especially microwave and hyperspectral infrared sounding techniques are found to give the largest impacts

Spectral Inverse Quantum (Spectral-IQ Method for Modeling Mesoporous Systems: Application on Silica Films by FTIR

Directory of Open Access Journals (Sweden)

Mihai V. Putz

2012-11-01

Full Text Available The present work advances the inverse quantum (IQ structural criterion for ordering and characterizing the porosity of the mesosystems based on the recently advanced ratio of the particle-to-wave nature of quantum objects within the extended Heisenberg uncertainty relationship through employing the quantum fluctuation, both for free and observed quantum scattering information, as computed upon spectral identification of the wave-numbers specific to the maximum of absorption intensity record, and to left-, right- and full-width at the half maximum (FWHM of the concerned bands of a given compound. It furnishes the hierarchy for classifying the mesoporous systems from more particle-related (porous, tight or ionic bindings to more wave behavior (free or covalent bindings. This so-called spectral inverse quantum (Spectral-IQ particle-to-wave assignment was illustrated on spectral measurement of FT-IR (bonding bands’ assignment for samples synthesized within different basic environment and different thermal treatment on mesoporous materials obtained by sol-gel technique with n-dodecyl trimethyl ammonium bromide (DTAB and cetyltrimethylammonium bromide (CTAB and of their combination as cosolvents. The results were analyzed in the light of the so-called residual inverse quantum information, accounting for the free binding potency of analyzed samples at drying temperature, and were checked by cross-validation with thermal decomposition techniques by endo-exo thermo correlations at a higher temperature.

Power-Law Template for IR Point Source Clustering

Science.gov (United States)

Addison, Graeme E.; Dunkley, Joanna; Hajian, Amir; Viero, Marco; Bond, J. Richard; Das, Sudeep; Devlin, Mark; Halpern, Mark; Hincks, Adam; Hlozek, Renee;

Synthesis and spectral studies of Pd(II) complexes with 2, 3-disubstituted quinazolin-(3H)-4-ones

International Nuclear Information System (INIS)

Prabhakar, B.; Lingaiah, P.; Laxima Reddy, K.

1991-01-01

A number of palladium(II) complexes of bidentate O-O and O-N donors, 2,3-disubstituted quinazoline-(3H)-4-ones, have been synthesized and characterized based on analytical, conductivity, magnetic, thermal, IR, electronic and PMR spectral data. The complexes of Pd(II) with ligands such as 2-(R)-3-(X)-substituted quinazoline-(3H)-4-ones, where R=methyl/phenyl and X=2'-hydroxybenzalimino (MHBQ/PHBQ), carboxymethyl (MCMQ/PCMQ), furfuralimino (MFQ/PFQ), acetamino (MAQ/PAQ), uramino (MUQ/PUQ) and thiouramino (MTUQ/PTUQ), yielded the complexes of the type [Pd(O-N) 2 ]Cl 2 and [Pd(O-O) 2 ]. The IR and PMR spectral data of the metal complexes indicate that MHQB, PHQB, MCMQ, and PCMQ act as uninegative bidentate ligands whereas MFQ, PFQ, MAQ, PAQ, MUQ, PUQ, MTUQ and PTUQ act as neutral bidentate ligands. The electronic spectral studies of these complexes indicate that they were square-planar geometry. (author). 23 refs., 2 tabs

Comparative Evaluation of Spectral Transmittance of Some Welding Glasses with ANSI Z87.1

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saeed Rahmani

2016-04-01

Full Text Available Background: Welding emits harmful rays to the eyes. We evaluate and compare the UV, blue light and IR transmittance characteristics of some currently available welding safety protectors with ANSI Z87.1 criteria.Materials and Methods: Three type of welding safety protectors (three of each type have been evaluated for spectral transmittance. One-sample T-test was performed to establish is there a statistically significant difference between the standard criteria and UV, blue and IR regions for the welding protectors (α=0.05.Results: In ultraviolet (UV (far and near region, two types of the tested protectors (P1, P2 transmitted lower than the maximum allowable value specified in the standard (P<0.001. In infrared (IR spectrum only one type (P3 transmitted lower than the maximum allowable value specified in the standard (P<0.001. In blue light region, all of the tested protectors transmitted lower than the maximum allowable value specified in the standard (P<0.001.Conclusion: Although all of the tested glasses could meet some parts of the criteria, but none of them could meet the complete spectral transmittance requirements of ANSI Z87.1.

Analysis of cosmetic residues on a single human hair by ATR FT-IR microspectroscopy.

Science.gov (United States)

Pienpinijtham, Prompong; Thammacharoen, Chuchaat; Naranitad, Suwimol; Ekgasit, Sanong

2018-05-15

In this work, ATR FT-IR spectra of single human hair and cosmetic residues on hair surface are successfully collected using a homemade dome-shaped Ge μIRE accessary installed on an infrared microscope. By collecting ATR spectra of hairs from the same person, the spectral patterns are identical and superimposed while different spectral features are observed from ATR spectra of hairs collected from different persons. The spectral differences depend on individual hair characteristics, chemical treatments, and cosmetics on hair surface. The "Contact-and-Collect" technique that transfers remarkable materials on the hair surface to the tip of the Ge μIRE enables an identification of cosmetics on a single hair. Moreover, the differences between un-split and split hairs are also studied in this report. These highly specific spectral features can be employed for unique identification or for differentiation of hairs based on the molecular structures of hairs and cosmetics on hairs. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of cosmetic residues on a single human hair by ATR FT-IR microspectroscopy

Science.gov (United States)

Pienpinijtham, Prompong; Thammacharoen, Chuchaat; Naranitad, Suwimol; Ekgasit, Sanong

2018-05-01

In this work, ATR FT-IR spectra of single human hair and cosmetic residues on hair surface are successfully collected using a homemade dome-shaped Ge μIRE accessary installed on an infrared microscope. By collecting ATR spectra of hairs from the same person, the spectral patterns are identical and superimposed while different spectral features are observed from ATR spectra of hairs collected from different persons. The spectral differences depend on individual hair characteristics, chemical treatments, and cosmetics on hair surface. The "Contact-and-Collect" technique that transfers remarkable materials on the hair surface to the tip of the Ge μIRE enables an identification of cosmetics on a single hair. Moreover, the differences between un-split and split hairs are also studied in this report. These highly specific spectral features can be employed for unique identification or for differentiation of hairs based on the molecular structures of hairs and cosmetics on hairs.

Spectral variation of the solar radiation during an eclipse

Directory of Open Access Journals (Sweden)

Peter Koepke

2001-05-01

Full Text Available The time dependent variation of the spectral extraterrestrial solar flux is modelled for the conditions during a total eclipse. These data are used to calculate irradiance and actinic flux at the Earth’s surface for atmospheric conditions of August 11, 1999 at Weihenstephan. These results are compared with measurements. It is shown, that the spectral composition of solar radiation varies during the eclipse, since solar limb darkening has a spectral dependence. The solar radiation differs from that of a hypothetical sun without limb darkening by up to 30% in the near IR at 1500 nm and 60% in the UV-B at 310 nm. As shown by a comparison of modelling and measurements, this spectral variation has to be taken into account for modelling of UV radiative quantities in the atmosphere and resulting photochemical processes. The effect of broken cloudiness on irradiance and actinic flux and its dependency on wavelength and receiver geometry is explained. Der Verlauf der spektralen extraterrestrischen solaren Strahlung wÄhrend einer Sonnenfinsternis wurde berechnet. Basierend auf diesen Daten, unter BerÜcksichtigung der atmosphÄrischen Bedingungen am 11. August 1999 in Weihenstephan, wurden Globalstrahlung und Aktinischer Fluss am Boden modelliert und mit Messwerten verglichen. Die spektrale Zusammensetzung der Strahlung Ändert sich wÄhrend einer Sonnenfinsternis, bedingt durch die wellenlÄngenabhÄngige Randverdunklung der Sonne. Im Vergleich zu einer hypothetischen Sonne ohne Randverdunklung ist die solare Strahlung im nahen IR um bis zu 30% gemindert und im UVB bei 310 nm um bis zu 60%. Diese spektralen Änderungen sollten bei der Modellierung von Strahlung, z.B. fÜr photochemische Prozesse berÜcksichtigt werden. Dies wurde durch Messung und Modellierung gezeigt. Der Einfluss von Wolken auf gemessene Werte von Globalstrahlung und Aktinischem Fluss wurde untersucht und erklÄrt.

Spectral properties of common intraocular lens (IOL) types

Science.gov (United States)

Milne, Peter J.; Chapon, Pascal F.; Hamaoui, Marie; Parel, Jean-Marie A.; Clayman, H.; Rol, Pascal O.

1999-06-01

Currently over 50 kinds of intraocular lenses (IOLs) are approved for patient use in the treatment of cataracts and ametropia. These lenses are manufactured from at least 2 kinds of silicones as well as several kinds of acrylic polymers including polyHEMA, Poly HOXEMA, a range of polymethacrylate and polyacrylate formulations. We sought to measure spectral transmission curves of a range of IOLS in the UV-visible and near IR spectral regions in order to better characterize their optical properties and to provide a baseline from which to assess their alteration following implantation over time. Consideration of how this may best be achieved are discussed. The variable ability of both explained IOLs and some samples from a range of manufacturers to block UV wavelengths is commented upon.

Stereoselective synthesis and spectral studies of some benzotriazolylacetyl hydrazones of 3-alkyl-2,6-diarylpiperidin-4-ones

Science.gov (United States)

Pillai, M. Velayutham; Rajeswari, K.; Kumar, C. Udhaya; Krishnan, K. Gokula; Mahendran, S.; Ramalingan, C.; Nagarajan, E. R.; Vidhyasagar, T.

2017-12-01

An effort to include biologically potent benzotriazole nucleus into piperidine ring is achieved through hydrazone formation. The characterization of the synthesized compounds was carried out using FT-IR, 1H &13C NMR, 1H-1H COSY, 1H-13C COSY, NOESY spectral techniques and GC-Mass spectrum. The spectral assignments were done without ambiguity using 2D-NMR techniques. The conformational preference of the piperidine ring deduced from the spectral studies is 'chair'. The diastereotopic nature of the methylene protons/methyl groups present in the molecules is revealed clearly in their spectral pattern observed.

IR reflectance spectroscopy of carbon dioxide clathrate hydrates. Implications for Saturn's icy moons.

Science.gov (United States)

Oancea, A.; Grasset, O.; Le Menn, E.; Bezacier, L.; Bollengier, O.; Le Mouélic, S.; Tobie, G.

2012-04-01

A CO2 spectral band was discovered by VIMS on the Saturn's satellites Dione, Hyperion, Iapetus and Phoebe [1]. The band position on the three first satellites corresponds to CO2 trapped in a complex material, but no indication exists whether this latter is water ice or some mineral or complex organic compound [1]. On Phoebe, the CO2 spectral band is consistent with solid CO2 or CO2 molecules trapped in the small cages of a clathrate hydrate structure [2]. It is thought that clathrate hydrates could play a significant role in the chemistry of the solar nebula [3] and in the physical evolution of astrophysical objects [4]. But so far, no clathrate hydrate structure has been observed in astrophysical environments. Moreover, identification of molecules trapped in a clathrate hydrate structure is extremely difficult because of the strong IR vibration modes of the water ice matrix. In this work, experimental IR reflectance spectra for CO2 clathrate hydrates are studied on grains and films. Clathrates are synthesized in a high pressure autoclave at low temperatures. IR spectral analysis is made with a low pressure and low temperature cryostat. These experimental conditions - 80 spectrum will be presented. A comparison between the absorption bands of CO2 clathrate hydrates obtained in our lab and CO2 absorption bands as detected by VIMS on the icy satellites of Saturn will be shown. This experimental work confirms that VIMS data are not consistent with the presence of structure I CO2 clathrate hydrates on the surface of the icy moons. Possibility of having metastable structure II still remains unsolved and will be discussed. [1] Dalton et al., Space Sci. Rev. 2010, 153 : 113-154. [2] Cruikshank D.P. et al, Icarus, 2010, 206: 561-572. [3] Mousis O. et al , Ap. J. 2009, 691: 1780-1786. [4] Choukroun M. et al, in Solar System Ices, edited by Castillo-Rogez, J. et al., 2011.

Extending Supernova Spectral Templates for Next Generation Space Telescope Observations

Science.gov (United States)

Roberts-Pierel, Justin; Rodney, Steven A.; Steven Rodney

2018-01-01

Widely used empirical supernova (SN) Spectral Energy Distributions (SEDs) have not historically extended meaningfully into the ultraviolet (UV), or the infrared (IR). However, both are critical for current and future aspects of SN research including UV spectra as probes of poorly understood SN Ia physical properties, and expanding our view of the universe with high-redshift James Webb Space Telescope (JWST) IR observations. We therefore present a comprehensive set of SN SED templates that have been extended into the UV and IR, as well as an open-source software package written in Python that enables a user to generate their own extrapolated SEDs. We have taken a sampling of core-collapse (CC) and Type Ia SNe to get a time-dependent distribution of UV and IR colors (U-B,r’-[JHK]), and then generated color curves are used to extrapolate SEDs into the UV and IR. The SED extrapolation process is now easily duplicated using a user’s own data and parameters via our open-source Python package: SNSEDextend. This work develops the tools necessary to explore the JWST’s ability to discriminate between CC and Type Ia SNe, as well as provides a repository of SN SEDs that will be invaluable to future JWST and WFIRST SN studies.

Power scaling of ultrafast mid-IR source enabled by high-power fiber laser technology

Energy Technology Data Exchange (ETDEWEB)

Zhou, Gengji

2017-11-15

Ultrafast laser sources with high repetition-rate (>10 MHz) and tunable in the mid-infrared (IR) wavelength range of 7-18 μm hold promise for many important spectroscopy applications. Currently, these ultrafast mid- to longwavelength-IR sources can most easily be achieved via difference-frequency generation (DFG) between a pump beam and a signal beam. However, current ultrafast mid- to longwavelength-IR sources feature a low average power, which limits their applications. In this thesis, we propose and demonstrate a novel approach to power scaling of DFG-based ultrafast mid-IR laser sources. The essence of this novel approach is the generation of a high-energy signal beam. Both the pump beam and the signal beam are derived from a home-built Yb-fiber laser system that emits 165-fs pulses centered at 1035 nm with 30-MHz repetition rate and 14.5-W average power (corresponding to 483-nJ pulse energy). We employ fiber-optic self-phase modulation (SPM) to broaden the laser spectrum and generate isolated spectral lobes. Filtering the rightmost spectral lobe leads to femtosecond pulses with >10 nJ pulse energy. Tunable between 1.1-1.2 μm, this SPM-enabled ultrafast source exhibits ∝100 times higher pulse energy than can be obtained from Raman soliton sources in this wavelength range. We use this SPM-enabled source as the signal beam and part of the Yb-fiber laser output as the pump beam. By performing DFG in GaSe crystals, we demonstrate that power scaling of a DFG-based mid-IR source can be efficiently achieved by increasing the signal energy. The resulting mid-IR source is tunable from 7.4 μm to 16.8 μm. Up to 5.04-mW mid-IR pulses centered at 11 μm are achieved. The corresponding pulse energy is 167 pJ, representing nearly one order of magnitude improvement compared with other reported DFG-based mid-IR sources at this wavelength. Despite of low pulse energy, Raman soliton sources have become a popular choice as the signal source. We carry out a detailed study on

Power scaling of ultrafast mid-IR source enabled by high-power fiber laser technology

International Nuclear Information System (INIS)

Zhou, Gengji

2017-11-01

Ultrafast laser sources with high repetition-rate (>10 MHz) and tunable in the mid-infrared (IR) wavelength range of 7-18 μm hold promise for many important spectroscopy applications. Currently, these ultrafast mid- to longwavelength-IR sources can most easily be achieved via difference-frequency generation (DFG) between a pump beam and a signal beam. However, current ultrafast mid- to longwavelength-IR sources feature a low average power, which limits their applications. In this thesis, we propose and demonstrate a novel approach to power scaling of DFG-based ultrafast mid-IR laser sources. The essence of this novel approach is the generation of a high-energy signal beam. Both the pump beam and the signal beam are derived from a home-built Yb-fiber laser system that emits 165-fs pulses centered at 1035 nm with 30-MHz repetition rate and 14.5-W average power (corresponding to 483-nJ pulse energy). We employ fiber-optic self-phase modulation (SPM) to broaden the laser spectrum and generate isolated spectral lobes. Filtering the rightmost spectral lobe leads to femtosecond pulses with >10 nJ pulse energy. Tunable between 1.1-1.2 μm, this SPM-enabled ultrafast source exhibits ∝100 times higher pulse energy than can be obtained from Raman soliton sources in this wavelength range. We use this SPM-enabled source as the signal beam and part of the Yb-fiber laser output as the pump beam. By performing DFG in GaSe crystals, we demonstrate that power scaling of a DFG-based mid-IR source can be efficiently achieved by increasing the signal energy. The resulting mid-IR source is tunable from 7.4 μm to 16.8 μm. Up to 5.04-mW mid-IR pulses centered at 11 μm are achieved. The corresponding pulse energy is 167 pJ, representing nearly one order of magnitude improvement compared with other reported DFG-based mid-IR sources at this wavelength. Despite of low pulse energy, Raman soliton sources have become a popular choice as the signal source. We carry out a detailed study on

Validation of Spectral Unmixing Results from Informed Non-Negative Matrix Factorization (INMF) of Hyperspectral Imagery

Science.gov (United States)

Wright, L.; Coddington, O.; Pilewskie, P.

2017-12-01

Hyperspectral instruments are a growing class of Earth observing sensors designed to improve remote sensing capabilities beyond discrete multi-band sensors by providing tens to hundreds of continuous spectral channels. Improved spectral resolution, range and radiometric accuracy allow the collection of large amounts of spectral data, facilitating thorough characterization of both atmospheric and surface properties. We describe the development of an Informed Non-Negative Matrix Factorization (INMF) spectral unmixing method to exploit this spectral information and separate atmospheric and surface signals based on their physical sources. INMF offers marked benefits over other commonly employed techniques including non-negativity, which avoids physically impossible results; and adaptability, which tailors the method to hyperspectral source separation. The INMF algorithm is adapted to separate contributions from physically distinct sources using constraints on spectral and spatial variability, and library spectra to improve the initial guess. Using this INMF algorithm we decompose hyperspectral imagery from the NASA Hyperspectral Imager for the Coastal Ocean (HICO), with a focus on separating surface and atmospheric signal contributions. HICO's coastal ocean focus provides a dataset with a wide range of atmospheric and surface conditions. These include atmospheres with varying aerosol optical thicknesses and cloud cover. HICO images also provide a range of surface conditions including deep ocean regions, with only minor contributions from the ocean surfaces; and more complex shallow coastal regions with contributions from the seafloor or suspended sediments. We provide extensive comparison of INMF decomposition results against independent measurements of physical properties. These include comparison against traditional model-based retrievals of water-leaving, aerosol, and molecular scattering radiances and other satellite products, such as aerosol optical thickness from

Planck intermediate results: XLIII. Spectral energy distribution of dust in clusters of galaxies

DEFF Research Database (Denmark)

Adam, R.; Ade, P. A R; Aghanim, N.

2016-01-01

Although infrared (IR) overall dust emission from clusters of galaxies has been statistically detected using data from the Infrared Astronomical Satellite (IRAS), it has not been possible to sample the spectral energy distribution (SED) of this emission over its peak, and thus to break the degene...

GOODS-HERSCHEL: IMPACT OF ACTIVE GALACTIC NUCLEI AND STAR FORMATION ACTIVITY ON INFRARED SPECTRAL ENERGY DISTRIBUTIONS AT HIGH REDSHIFT

Energy Technology Data Exchange (ETDEWEB)

Kirkpatrick, Allison; Pope, Alexandra [Department of Astronomy, University of Massachusetts, Amherst, MA 01002 (United States); Alexander, David M. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Charmandaris, Vassilis [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003, Heraklion (Greece); Daddi, Emmanuele; Elbaz, David; Gabor, Jared; Mullaney, James; Pannella, Maurilio; Aussel, Herve; Bournaud, Frederic; Dasyra, Kalliopi [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Dickinson, Mark [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Hwang, Ho Seong [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Ivison, Rob [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Scott, Douglas [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Altieri, Bruno; Coia, Daniela [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, E-28691 Madrid (Spain); Buat, Veronique [Laboratoire d' Astrophysique de Marseille (LAM), Universite d' Aix-Marseille, CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France); Dannerbauer, Helmut, E-mail: kirkpatr@astro.umass.edu [Institut fuer Astrophysik, Universitaet Wien, Tuerkenschanzstrasse 17, A-1180 Wien (Austria); and others

2012-11-10

We explore the effects of active galactic nuclei (AGNs) and star formation activity on the infrared (0.3-1000 {mu}m) spectral energy distributions (SEDs) of luminous infrared galaxies from z = 0.5 to 4.0. We have compiled a large sample of 151 galaxies selected at 24 {mu}m (S {sub 24} {approx}> 100 {mu}Jy) in the GOODS-N and ECDFS fields for which we have deep Spitzer IRS spectroscopy, allowing us to decompose the mid-IR spectrum into contributions from star formation and AGN activity. A significant portion ({approx}25%) of our sample is dominated by an AGN (>50% of the mid-IR luminosity) in the mid-IR. Based on the mid-IR classification, we divide our full sample into four sub-samples: z {approx} 1 star-forming (SF) sources, z {approx} 2 SF sources, AGNs with clear 9.7 {mu}m silicate absorption, and AGNs with featureless mid-IR spectra. From our large spectroscopic sample and wealth of multi-wavelength data, including deep Herschel imaging at 100, 160, 250, 350, and 500 {mu}m, we use 95 galaxies with complete spectral coverage to create a composite SED for each sub-sample. We then fit a two-temperature component modified blackbody to the SEDs. We find that the IR SEDs have similar cold dust temperatures, regardless of the mid-IR power source, but display a marked difference in the warmer dust temperatures. We calculate the average effective temperature of the dust in each sub-sample and find a significant ({approx}20 K) difference between the SF and AGN systems. We compare our composite SEDs to local templates and find that local templates do not accurately reproduce the mid-IR features and dust temperatures of our high-redshift systems. High-redshift IR luminous galaxies contain significantly more cool dust than their local counterparts. We find that a full suite of photometry spanning the IR peak is necessary to accurately account for the dominant dust temperature components in high-redshift IR luminous galaxies.

Spectral Signature of Radiative Forcing by East Asian Dust-Soot Mixture

Science.gov (United States)

Zhu, A.; Ramanathan, V.

2007-12-01

The Pacific Dust Experiment (PACDEX) provides the first detailed sampling of dust-soot mixtures from the western Pacific to the eastern Pacific Ocean. The data includes down and up spectral irradiance, mixing state of dust and soot, and other aerosol properties. This study attempts to simulate the radiative forcing by dust-soot mixtures during the experimental period. The MODTRAN band model was employed to investigate the spectral signatures of solar irradiance change induced by aerosols at moderate spectral resolutions. For the short wave band (300-1100nm) used in this study, the reduction of downward irradiance at surface by aerosols greatly enhances with increasing wavelength in the UV band (300-400nm), reaches a maximum in the blue band, then gradually decreases toward the red band. In the near-IR band (700-1100nm), irradiance reduction by aerosols shows great fluctuations in the band with center wavelength at around 940nm, 820nm, 720nm, 760nm, 690nm, where the aerosol effect is overwhelmed by the water vapor and O2 absorptions. The spectral pattern of irradiance reduction varies for different aerosol species. The maximum reduction lies at around 450nm for soot, and shifting to about 490nm for East Asian mineral dust. It's worth noting that although soot aerosols reduce more irradiance than East Asian dust in the UV and blue band, the impact of dust to the irradiance exceeds that by soot at the longer wavelength band (i.e. around 550nm). The reduction of irradiance by East Asian dust (soot) in the UV band, visible band, and near-IR accounts for about 6% (10%), 56% (64%), and 38% (26%) of total irradiance reduction. As large amount of soot aerosols are involved during the long range transport of East Asian dust, the optical properties of dust aerosols are modified with different mixing state with soot, the spectral pattern of the irradiance reduction will be changed. The study of aerosol forcing at moderate spectral resolutions has the potential application for

Improved spectral absorption coefficient grouping strategy of wide band k-distribution model used for calculation of infrared remote sensing signal of hot exhaust systems

Science.gov (United States)

Hu, Haiyang; Wang, Qiang

2018-07-01

A new strategy for grouping spectral absorption coefficients, considering the influences of both temperature and species mole ratio inhomogeneities on correlated-k characteristics of the spectra of gas mixtures, has been deduced to match the calculation method of spectral overlap parameter used in multiscale multigroup wide band k-distribution model. By comparison with current spectral absorption coefficient grouping strategies, for which only the influence of temperature inhomogeneity on the correlated-k characteristics of spectra of single species was considered, the improvements in calculation accuracies resulting from the new grouping strategy were evaluated using a series of 0D cases in which radiance under 3-5-μm wave band emitted by hot combustion gas of hydrocarbon fuel was attenuated by atmosphere with quite different temperature and mole ratios of water vapor and carbon monoxide to carbon dioxide. Finally, evaluations are presented on the calculation of remote sensing thermal images of transonic hot jet exhausted from a chevron ejecting nozzle with solid wall cooling system.

The TApIR experiment. IR absorption spectra of liquid hydrogen isotopologues; Das TApIR Experiment IR-Absorptionsspektren fluessiger Wasserstoffisotopologe

Energy Technology Data Exchange (ETDEWEB)

Groessle, Robin

2015-11-27

The scope of the thesis is the infrared absorption spectroscopy of liquid hydrogen isotopologues with the tritium absorption infrared spectroscopy (TApIR) experiment at the tritium laboratory Karlsruhe (TLK). The calibration process from the sample preparation to the reference measurements are described. A further issue is the classical evaluation of FTIR absorption spectra and the extension using the rolling circle filter (RCF) including the effects on statistical and systematical errors. The impact of thermal and nuclear spin temperature on the IR absorption spectra is discussed. An empirical based modeling for the IR absorption spectra of liquid hydrogen isotopologues is performed.

Effectiveness of recycling light in ultra-bright short-arc discharge lamps.

Science.gov (United States)

Malul, Asher; Nakar, Doron; Feuermann, Daniel; Gordon, Jeffrey M

2007-10-17

Recycling light back into a plasma lamp's radiant zone can enhance its radiance. Measurements are reported for the effectiveness, spectral properties and modified plasma radiance maps that result from light recycling with a specular hemispherical mirror in commercial 150 W ultrabright Xenon short-arc discharge lamps, motivated by projection, biomedical and high-temperature furnace applications. For certain spectral windows and plasma arc regions, radiance can be heightened by up to 70%. However, the overall light recycling efficiency is reduced to about half this value due to lamp geometry. The manner in which light-plasma interactions affect light recycling efficacy is also elucidated.

New horizons for Supercontinuum light sources: from UV to mid-IR

DEFF Research Database (Denmark)

Thomsen, Carsten L.; Nielsen, Frederik Donbæk; Johansen, Jeppe

2013-01-01

Commercially available supercontinuum sources continue to experience a strong growth in a wide range of industrial and scientific applications. In addition, there is a significant research effort focused on extending the wavelength coverage both towards UV and Mid-IR. Broadband sources covering...... and novel pumping schemes, whereas shifting the spectrum further towards the UV has been based on sophisticated microstructure fiber designs. Here we present our latest developments in tailoring the power and spectral coverage of spatially coherent broadband supercontinuum sources....

Tarptautinio turizmo raida ir vystymo prognozės Lietuvoje ir Lenkijoje

OpenAIRE

Veličkaitė, Dalia

2009-01-01

Išanalizuota ir įvertinta Lietuvos ir Lenkijos atvykstamojo turizmo raida 2000- 2007m., užsienio turistų srautai, apgyvendinimo paslaugų paklausa, turistų tikslai ir kelionių transporto pasirinkimas, turistų išlaidos ir šalių turizmo pajamos, iškeltos atvykstamojo turizmo problemos bei pateikti jų sprendimo siūlymai.paskutinėje darbo dalyje buvo atliktos 2008- 2015metų Lietuvos ir Lenkijos turizmo raidos prognozės. In the final master work Lithuanian and Poland arriving tourism development...

Mars atmosphere studies with the SPICAM IR emission phase function observations

Science.gov (United States)

Trokhimovskiy, Alexander; Fedorova, Anna; Montmessin, Franck; Korablev, Oleg; Bertaux, Jean-Loup

Emission Phase Function (EPF) observations is a powerful tool for characterization of atmosphere and surface. EPF sequence provides the extensive coverage of scattering angles above the targeted surface location which allow to separate the surface and aerosol scattering, study a vertical distribution of minor species and aerosol properties. SPICAM IR instrument on Mars Express mission provides continuous atmospheric observations in near IR (1-1.7 mu) in nadir and limb starting from 2004. For the first years of SPICAM operation only a very limited number of EPFs was performed. But from the mid 2013 (Ls=225, MY31) SPICAM EPF observations become rather regular. Based on the multiple-scattering radiative transfer model SHDOM, we analyze equivalent depths of carbon dioxide (1,43 mu) and water vapour (1,38 mu) absorption bands and their dependence on airmass during observation sequence to get aerosol optical depths and properties. The derived seasonal dust opacities from near IR can be used to retrieve the size distribution from comparison with simultaneous results of other instruments in different spectral ranges. Moreover, the EPF observations of water vapour band allow to access poorly known H2O vertical distribution for different season and locations.

Photochemistry of Fe:H2O Adducts in Argon Matrixes: A Combined Experimental and Theoretical Study in the Mid-IR and UV-Visible Regions.

Science.gov (United States)

Deguin, Vincent; Mascetti, Joëlle; Simon, Aude; Ben Amor, Nadia; Aupetit, Christian; Latournerie, Sandra; Noble, Jennifer A

2018-01-18

The photochemistry of Fe:H 2 O adducts is of interest in fields as diverse as catalysis and astrochemistry. Industrially, iron can be used as a catalyst to convert H 2 O to H 2 , whereas in the interstellar medium it may be an important component of dust grains, influencing the chemistry on their icy surfaces. This study consisted of the deposition and spectral characterization of binary systems of atomic iron with H 2 O in cryogenic argon matrixes. In this way, we were able to obtain information about the interaction of the two species; we observed the formation of adducts of iron monomers and dimers with water molecules in the mid-IR and UV-visible spectral domains. Upon irradiation with a UV radiation source, the iron species were inserted into the water molecules to form HFeOH and HFe 2 OH, leading in some cases to the formation of FeO possibly accompanied by the production of H 2 . DFT and correlated multireference wave function calculations confirmed our attributions. This combination of IR and UV-visible spectroscopy with theoretical calculations allowed us to determine, for the first time, the spectral characteristics of iron adducts and their photoproducts in the UV-visible and in the OH stretching region of the mid-IR domain.

Electronic structure, local magnetism, and spin-orbit effects of Ir(IV)-, Ir(V)-, and Ir(VI)-based compounds

Energy Technology Data Exchange (ETDEWEB)

Laguna-Marco, M. A.; Kayser, P.; Alonso, J. A.; Martínez-Lope, M. J.; van Veenendaal, M.; Choi, Y.; Haskel, D.

2015-06-01

Element- and orbital-selective x-ray absorption and magnetic circular dichroism measurements are carried out to probe the electronic structure and magnetism of Ir 5d electronic states in double perovskite Sr2MIrO6 (M = Mg, Ca, Sc, Ti, Ni, Fe, Zn, In) and La2NiIrO6 compounds. All the studied systems present a significant influence of spin-orbit interactions in the electronic ground state. In addition, we find that the Ir 5d local magnetic moment shows different character depending on the oxidation state despite the net magnetization being similar for all the compounds. Ir carries an orbital contribution comparable to the spin contribution for Ir4+ (5d(5)) and Ir5+ (5d(4)) oxides, whereas the orbital contribution is quenched for Ir6+ (5d(3)) samples. Incorporation of a magnetic 3d atom allows getting insight into the magnetic coupling between 5d and 3d transition metals. Together with previous susceptibility and neutron diffractionmeasurements, the results indicate that Ir carries a significant local magnetic moment even in samples without a 3d metal. The size of the (small) net magnetization of these compounds is a result of predominant antiferromagnetic interactions between local moments coupled with structural details of each perovskite structure

IR-IR Conformation Specific Spectroscopy of Na+(Glucose) Adducts

Science.gov (United States)

Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

2018-01-01

We report an IR-IR double resonance study of the structural landscape present in the Na+(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na+(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctive Na+ coordination. [Figure not available: see fulltext.

Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 2: Validation case study

Directory of Open Access Journals (Sweden)

S. D. Eckermann

2006-01-01

Full Text Available Two-dimensional radiance maps from Channel 9 (~60–90 hPa of the Advanced Microwave Sounding Unit (AMSU-A, acquired over southern Scandinavia on 14 January 2003, show plane-wave-like oscillations with a wavelength λh of ~400–500 km and peak brightness temperature amplitudes of up to 0.9 K. The wave-like pattern is observed in AMSU-A radiances from 8 overpasses of this region by 4 different satellites, revealing a growth in the disturbance amplitude from 00:00 UTC to 12:00 UTC and a change in its horizontal structure between 12:00 UTC and 20:00 UTC. Forecast and hindcast runs for 14 January 2003 using high-resolution global and regional numerical weather prediction (NWP models generate a lower stratospheric mountain wave over southern Scandinavia with peak 90 hPa temperature amplitudes of ~5–7 K at 12:00 UTC and a similar horizontal wavelength, packet width, phase structure and time evolution to the disturbance observed in AMSU-A radiances. The wave's vertical wavelength is ~12 km. These NWP fields are validated against radiosonde wind and temperature profiles and airborne lidar profiles of temperature and aerosol backscatter ratios acquired from the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II. Both the amplitude and phase of the stratospheric mountain wave in the various NWP fields agree well with localized perturbation features in these suborbital measurements. In particular, we show that this wave formed the type II polar stratospheric clouds measured by the DC-8 lidar. To compare directly with the AMSU-A data, we convert these validated NWP temperature fields into swath-scanned brightness temperatures using three-dimensional Channel 9 weighting functions and the actual AMSU-A scan patterns from each of the 8 overpasses of this region. These NWP-based brightness temperatures contain two-dimensional oscillations due to this resolved stratospheric mountain wave that have an amplitude, wavelength

PKCδ-mediated IRS-1 Ser24 phosphorylation negatively regulates IRS-1 function

International Nuclear Information System (INIS)

Greene, Michael W.; Ruhoff, Mary S.; Roth, Richard A.; Kim, Jeong-a; Quon, Michael J.; Krause, Jean A.

2006-01-01

The IRS-1 PH and PTB domains are essential for insulin-stimulated IRS-1 Tyr phosphorylation and insulin signaling, while Ser/Thr phosphorylation of IRS-1 disrupts these signaling events. To investigate consensus PKC phosphorylation sites in the PH-PTB domains of human IRS-1, we changed Ser24, Ser58, and Thr191 to Ala (3A) or Glu (3E), to block or mimic phosphorylation, respectively. The 3A mutant abrogated the inhibitory effect of PKCδ on insulin-stimulated IRS-1 Tyr phosphorylation, while reductions in insulin-stimulated IRS-1 Tyr phosphorylation, cellular proliferation, and Akt activation were observed with the 3E mutant. When single Glu mutants were tested, the Ser24 to Glu mutant had the greatest inhibitory effect on insulin-stimulated IRS-1 Tyr phosphorylation. PKCδ-mediated IRS-1 Ser24 phosphorylation was confirmed in cells with PKCδ catalytic domain mutants and by an RNAi method. Mechanistic studies revealed that IRS-1 with Ala and Glu point mutations at Ser24 impaired phosphatidylinositol-4,5-bisphosphate binding. In summary, our data are consistent with the hypothesis that Ser24 is a negative regulatory phosphorylation site in IRS-1

Impact of Assimilation of Conventional and Satellite Radiance GTS Observations on Simulation of Mesoscale Convective System Over Southeast India Using WRF-3DVar

Science.gov (United States)

Madhulatha, A.; Rajeevan, M.; Bhowmik, S. K. Roy; Das, A. K.

2018-01-01

The primary goal of present study is to investigate the impact of assimilation of conventional and satellite radiance observations in simulating the mesoscale convective system (MCS) formed over south east India. An assimilation methodology based on Weather Research and Forecasting model three dimensional variational data assimilation is considered. Few numerical experiments are carried out to examine the individual and combined impact of conventional and non-conventional (satellite radiance) observations. After the successful inclusion of additional observations, strong analysis increments of temperature and moisture fields are noticed and contributed to significant improvement in model's initial fields. The resulting model simulations are able to successfully reproduce the prominent synoptic features responsible for the initiation of MCS. Among all the experiments, the final experiment in which both conventional and satellite radiance observations assimilated has showed considerable impact on the prediction of MCS. The location, genesis, intensity, propagation and development of rain bands associated with the MCS are simulated reasonably well. The biases of simulated temperature, moisture and wind fields at surface and different pressure levels are reduced. Thermodynamic, dynamic and vertical structure of convective cells associated with the passage of MCS are well captured. Spatial distribution of rainfall is fairly reproduced and comparable to TRMM observations. It is demonstrated that incorporation of conventional and satellite radiance observations improved the local and synoptic representation of temperature, moisture fields from surface to different levels of atmosphere. This study highlights the importance of assimilation of conventional and satellite radiances in improving the models initial conditions and simulation of MCS.

Analysis of the development of missile-borne IR imaging detecting technologies

Science.gov (United States)

Fan, Jinxiang; Wang, Feng

2017-10-01

Today's infrared imaging guiding missiles are facing many challenges. With the development of targets' stealth, new-style IR countermeasures and penetrating technologies as well as the complexity of the operational environments, infrared imaging guiding missiles must meet the higher requirements of efficient target detection, capability of anti-interference and anti-jamming and the operational adaptability in complex, dynamic operating environments. Missileborne infrared imaging detecting systems are constrained by practical considerations like cost, size, weight and power (SWaP), and lifecycle requirements. Future-generation infrared imaging guiding missiles need to be resilient to changing operating environments and capable of doing more with fewer resources. Advanced IR imaging detecting and information exploring technologies are the key technologies that affect the future direction of IR imaging guidance missiles. Infrared imaging detecting and information exploring technologies research will support the development of more robust and efficient missile-borne infrared imaging detecting systems. Novelty IR imaging technologies, such as Infrared adaptive spectral imaging, are the key to effectively detect, recognize and track target under the complicated operating and countermeasures environments. Innovative information exploring techniques for the information of target, background and countermeasures provided by the detection system is the base for missile to recognize target and counter interference, jamming and countermeasure. Modular hardware and software development is the enabler for implementing multi-purpose, multi-function solutions. Uncooled IRFPA detectors and High-operating temperature IRFPA detectors as well as commercial-off-the-shelf (COTS) technology will support the implementing of low-cost infrared imaging guiding missiles. In this paper, the current status and features of missile-borne IR imaging detecting technologies are summarized. The key

Pulse shaping for high data rate ultra-wideband wireless transmission under the Russian spectral emission mask

DEFF Research Database (Denmark)

Rommel, Simon; Grakhova, Elizaveta P.; Jurado-Navas, Antonio

2017-01-01

This paper addresses impulse-radio ultra-wideband (IR-UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well......-known shapes such as the Gaussian, root-raised cosine, hyperbolic secant, and the frequency B-spline wavelet are used to form linear combinations of component pulses, shaped to make efficient use of the spectral emission mask. Analytical BER values are derived using a Nakagami-m model, and good agreement......-UWB transmission under the strict regulations of the Russian spectral emission mask....

Multi-pollutants sensors based on near-IR telecom lasers and mid-IR difference frequency generation: development and applications; Instruments de mesure multi-polluants par spectroscopie infrarouge bases sur des lasers fibres et par generation de difference de frequences: developpement et applications

Energy Technology Data Exchange (ETDEWEB)

Cousin, J

2006-12-15

At present the detection of VOC and other anthropic trace pollutants is an important challenge in the measurement of air quality. Infrared spectroscopy, allowing spectral regions rich in molecular absorption to be probed, is a suitable technique for in-situ monitoring of the air pollution. Thus the aim of this work was to develop instruments capable of detecting multiple pollutants for in-situ monitoring by IR spectroscopy. A first project benefited from the availability of the telecommunications lasers emitting in near-IR. This instrument was based on an external cavity diode laser (1500 - 1640 nm) in conjunction with a multipass cell (100 m). The detection sensitivity was optimised by employing a balanced detection and a sweep integration procedure. The instrument developed is deployable for in-situ measurements with a sensitivity of < 10{sup -8} cm{sup -1} Hz{sup -1/2} and allowed the quantification of chemical species such as CO{sub 2}, CO, C{sub 2}H{sub 2}, CH{sub 4} and the determination of the isotopic ratio {sup 13}CO{sub 2}/{sup 12}CO{sub 2} in combustion environment The second project consisted in mixing two near-IR fiber lasers in a non-linear crystal (PPLN) in order to produce a laser radiation by difference frequency generation in the middle-IR (3.15 - 3.43 {mu}m), where the absorption bands of the molecules are the most intense. The first studies with this source were carried out on detection of ethylene (C{sub 2}H{sub 4}) and benzene (C{sub 6}H{sub 6}). Developments, characterizations and applications of these instruments in the near and middle IR are detailed and the advantages of the 2 spectral ranges is highlighted. (author)

Using AVIRIS for in-flight calibration of the spectral shifts of SPOT-HRV and of AVHRR?

Science.gov (United States)

Willart-Soufflet, Veronique; Santer, Richard

1993-01-01

The response of a satellite sensor varies during its lifetime; internal calibration devices can be used to follow the sensor degradation or in-flight calibrations are conducted from estimates of the radiance at satellite level for well predictable situations. Changes in gain are evaluated assuming that the spectral response of the sensor is stable with time; i.e., that the filter response as well as the optics or the electronics are not modified since the prelaunch determinations. Nevertheless, there is some evidence that the SPOT interferometer filters are affected by outgassing effects during the launch. Tests in vacuum chambers indicated a narrowing of the filters with a shift of the upper side towards the blue of about 10 nm which is more over consistant with the loss of gain observed during the launch. Also, during the lifetime of SPOT, the relationship between the loss of sensitivity and the filter bandwidth may correspond to this effect. On the other hand, the inconsistancy of the NOAA7 calibration between two methods (desert and ocean) having a different spectral sensitivity may indicate a spectral problem with a shift of the central wavelength of -20 nm. The basic idea here is to take advantage of the good spectral definition of AVIRIS to monitor these potential spectral degradations with an experimental opportunity provided by a field campaign held in La Crau (S.E. of France) in June 1991 which associated ground-based measurements and AVIRIS, SPOT2, NOAA-11 overpasses over both the calibration site of La Crau and an agricultural area.

Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

Energy Technology Data Exchange (ETDEWEB)

Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale [Synchrotron SOLEIL, L’Orme des Merisiers, F-91192 Gif-sur-Yvette (France); Manceron, Laurent [Synchrotron SOLEIL, L’Orme des Merisiers, F-91192 Gif-sur-Yvette (France); Laboratoire MONARIS, CNRS-Université Pierre et Marie Curie, UMR 8233, 4 Place Jussieu, F-75252 Paris Cedex (France)

2016-06-15

When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6–20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

Detection of Daytime Arctic Clouds using MISR and MODIS Data

National Research Council Canada - National Science Library

Shi, Tao; Clothiaux, Eugene E; Yu, Bin; Braverman, Amy J; Groff, David N

2006-01-01

...) 7 are used operationally for detection of clouds in daytime polar regions. While the information content of clouds inherent in spectral radiances is familiar, the information content of clouds contained in angular radiances (i.e...

Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

Science.gov (United States)

Grossan, Bruce; Kistaubayev, M.; Smoot, G.; Scherr, L.

2017-06-01

While the afterglow phase of gamma-ray bursts (GRBs) has been extensively measured, detections of prompt emission (i.e. during bright X-gamma emission) are more limited. Some prompt optical measurements are regularly made, but these are typically in a single wide band, with limited time resolution, and no measurement of spectral shape. Some models predict a synchrotron self-absorption spectral break somewhere in the IR-optical region. Measurement of the absorption frequency would give extensive information on each burst, including the electron Lorentz factor, the radius of emission, and more (Shen & Zhang 2008). Thus far the best prompt observations have been explained invoking a variety of models, but often with a non-unique interpretation. To understand this apparently heterogeneous behavior, and to reduce the number of possible models, it is critical to add data on the optical - IR spectral shape.Long GRB prompt X-gamma emission typically lasts ~40-80 s. The Swift BAT instrument rapidly measures GRB positions to within a few arc minutes and communicates them via the internet within a few seconds. We have measured the time for a fast-moving D=700 mm telescope to point and settle to be less than 9 s anywhere on the observable sky. Therefore, the majority of prompt optical-IR emission can be measured responding to BAT positions with this telescope. In this presentation, we describe our observing and science programs, and give our design for the Burst Simultaneous Three-channel Instrument (BSTI), which uses dichroics to send eparate bands to 3 cameras. Two EMCCD cameras, give high-time resolution in B and V; a third camera with a HgCdTe sensor covers H band, allowing us to study extinguished bursts. For a total exposure time of 10 s, we find a 5 sigma sensitivity of 21.3 and 20.3 mag in B and R for 1" seeing and Kitt Peak sky brightness, much fainter than typical previous prompt detections. We estimate 5 sigma H-band sensitivity for an IR optimized telescope to be

Level 0 to 1 processing of the imaging Fourier transform spectrometer GLORIA: generation of radiometrically and spectrally calibrated spectra

Directory of Open Access Journals (Sweden)

A. Kleinert

2014-12-01

Full Text Available The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA is an imaging Fourier transform spectrometer that is capable of operating on various high-altitude research aircraft. It measures the atmospheric emission in the thermal infrared spectral region in limb and nadir geometry. GLORIA consists of a classical Michelson interferometer combined with an infrared camera. The infrared detector has a usable area of 128 × 128 pixels, measuring up to 16 384 interferograms simultaneously. Imaging Fourier transform spectrometers impose a number of challenges with respect to instrument calibration and algorithm development. The optical setup with extremely high optical throughput requires the development of new methods and algorithms for spectral and radiometric calibration. Due to the vast amount of data there is a high demand for scientifically intelligent optimisation of the data processing. This paper outlines the characterisation and processing steps required for the generation of radiometrically and spectrally calibrated spectra. Methods for performance optimisation of the processing algorithm are presented. The performance of the data processing and the quality of the calibrated spectra are demonstrated for measurements collected during the first deployments of GLORIA on aircraft.

Photosynthetic accessory pigments: evidence for the influence of phycoerythrin on the submarine light field

International Nuclear Information System (INIS)

Hoge, F.E.; Swift, R.N.

1990-01-01

Oceanic phytoplankton chlorophyll is known to produce a very significant influence on the optical properties of the ocean. The chlorophyll-driven optical properties are in fact so strong as to allow global satellite mapping of the pigment concentration in the upper ocean using upwelled waterleaving radiances. In this paper, extensive experimental evidence is presented to strongly suggest that upwelled water-leaving spectral radiances (and therefore the submarine light field source) also include physical scattering and absorption effects of photosynthetic accessory pigments such as phycoerythrin. In the water column, the presence of phycoerythrin was measured over wide regions of the ocean using well-established airborne laser-induced spectral fluorescence techniques. Active-passive correlation spectroscopy methods revealed that concurrently measured water-leaving spectral radiances in the ∼ 600 nm spectral region were highly correlated with the laser-induced phycoerythrin pigment fluorescence. The analysis was performed on data sets in which the phycoerythrin and chlorophyll fluorescence were not coherent in order to permit the unambiguous evaluation of results. (author)

Identification and characterization of salmonella serotypes using DNA spectral characteristics by fourier transform infrared (FT-IR) spectroscopy

Science.gov (United States)

Analysis of DNA samples of Salmonella serotypes (Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky) were performed using Fourier transform infrared spectroscopy (FT-IR) spectrometer by placing directly in contact with a diamond attenua...

Sugar and acid content of Citrus prediction modeling using FT-IR fingerprinting in combination with multivariate statistical analysis.

Science.gov (United States)

Song, Seung Yeob; Lee, Young Koung; Kim, In-Jung

2016-01-01

A high-throughput screening system for Citrus lines were established with higher sugar and acid contents using Fourier transform infrared (FT-IR) spectroscopy in combination with multivariate analysis. FT-IR spectra confirmed typical spectral differences between the frequency regions of 950-1100 cm(-1), 1300-1500 cm(-1), and 1500-1700 cm(-1). Principal component analysis (PCA) and subsequent partial least square-discriminant analysis (PLS-DA) were able to discriminate five Citrus lines into three separate clusters corresponding to their taxonomic relationships. The quantitative predictive modeling of sugar and acid contents from Citrus fruits was established using partial least square regression algorithms from FT-IR spectra. The regression coefficients (R(2)) between predicted values and estimated sugar and acid content values were 0.99. These results demonstrate that by using FT-IR spectra and applying quantitative prediction modeling to Citrus sugar and acid contents, excellent Citrus lines can be early detected with greater accuracy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Robustness of the charge-ordered phases in IrTe2 against photoexcitation

Science.gov (United States)

Monney, C.; Schuler, A.; Jaouen, T.; Mottas, M.-L.; Wolf, Th.; Merz, M.; Muntwiler, M.; Castiglioni, L.; Aebi, P.; Weber, F.; Hengsberger, M.

2018-02-01

We present a time-resolved angle-resolved photoelectron spectroscopy study of IrTe2, which undergoes two first-order structural and charge-ordered phase transitions on cooling below 270 K and below 180 K. The possibility of inducing a phase transition by photoexcitation with near-infrared femtosecond pulses is investigated in the charge-ordered phases. We observe changes of the spectral function occurring within a few hundreds of femtoseconds and persisting up to several picoseconds, which we interpret as a partial photoinduced phase transition (PIPT). The necessary time for photoinducing these spectral changes increases with increasing photoexcitation density and reaches time scales longer than the rise time of the transient electronic temperature. We conclude that the PIPT is driven by a transient increase of the lattice temperature following the energy transfer from the electrons. However, the photoinduced changes of the spectral function are small, which indicates that the low-temperature phase is particularly robust against photoexcitation. We suggest that the system might be trapped in an out-of-equilibrium state, for which only a partial structural transition is achieved.

SNSEDextend: SuperNova Spectral Energy Distributions extrapolation toolkit

Science.gov (United States)

Pierel, Justin D. R.; Rodney, Steven A.; Avelino, Arturo; Bianco, Federica; Foley, Ryan J.; Friedman, Andrew; Hicken, Malcolm; Hounsell, Rebekah; Jha, Saurabh W.; Kessler, Richard; Kirshner, Robert; Mandel, Kaisey; Narayan, Gautham; Filippenko, Alexei V.; Scolnic, Daniel; Strolger, Louis-Gregory

2018-05-01

SNSEDextend extrapolates core-collapse and Type Ia Spectral Energy Distributions (SEDs) into the UV and IR for use in simulations and photometric classifications. The user provides a library of existing SED templates (such as those in the authors' SN SED Repository) along with new photometric constraints in the UV and/or NIR wavelength ranges. The software then extends the existing template SEDs so their colors match the input data at all phases. SNSEDextend can also extend the SALT2 spectral time-series model for Type Ia SN for a "first-order" extrapolation of the SALT2 model components, suitable for use in survey simulations and photometric classification tools; as the code does not do a rigorous re-training of the SALT2 model, the results should not be relied on for precision applications such as light curve fitting for cosmology.

Characterization by Fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of a carbosilane dendrimer with peripheral ammonium groups

Energy Technology Data Exchange (ETDEWEB)

Popescu, Maria-Cristina, E-mail: cpopescu@icmpp.ro [' Petru Poni' Institute of Macromolecular Chemistry (Romania); Gomez, Rafael; Mata, Fco Javier de la; Rasines, Beatriz [Universidad de Alcala, Departamento de Quimica Inorganica (Spain); Simionescu, Bogdan C. [' Petru Poni' Institute of Macromolecular Chemistry (Romania)

2013-06-15

Fourier transform infrared spectroscopy and 2D correlation spectroscopy were used to study the microstructural changes occurring on heating of a new carbosilane dendrimer with peripheral ammonium groups. Temperature-dependent spectral variations in the 3,010-2,710, 1,530-1,170, and 1,170-625 cm{sup -1} regions were monitored during the heating process. The dependence, on temperature, of integral absorptions and position of spectral bands was established and the spectral modifications associated with molecular conformation rearrangements, allowing molecular shape changes, were found. Before 180 Degree-Sign C, the studied carbosilane dendrimer proved to be stable, while at higher temperatures it oxidizes and Si-O groups appear. 2D IR correlation spectroscopy gives new information about the effect of temperature on the structure and dynamics of the system. Synchronous and asynchronous spectra indicate that, at low temperature, conformational changes of CH{sub 3} and CH{sub 3}-N{sup +} groups take place first. With increasing temperature, the intensity variation of the CH{sub 2}, C-N, Si-C and C-C groups from the dendritic core is faster than that of the terminal units. This indicates that, with increasing temperature, the segments of the dendritic core obtain enough energy to change their conformation more easily as compared to the terminal units, due to their internal flexibility.

Characterization by Fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of a carbosilane dendrimer with peripheral ammonium groups

International Nuclear Information System (INIS)

Popescu, Maria-Cristina; Gómez, Rafael; Mata, Fco Javier de la; Rasines, Beatriz; Simionescu, Bogdan C.

2013-01-01

Fourier transform infrared spectroscopy and 2D correlation spectroscopy were used to study the microstructural changes occurring on heating of a new carbosilane dendrimer with peripheral ammonium groups. Temperature-dependent spectral variations in the 3,010–2,710, 1,530–1,170, and 1,170–625 cm −1 regions were monitored during the heating process. The dependence, on temperature, of integral absorptions and position of spectral bands was established and the spectral modifications associated with molecular conformation rearrangements, allowing molecular shape changes, were found. Before 180 °C, the studied carbosilane dendrimer proved to be stable, while at higher temperatures it oxidizes and Si–O groups appear. 2D IR correlation spectroscopy gives new information about the effect of temperature on the structure and dynamics of the system. Synchronous and asynchronous spectra indicate that, at low temperature, conformational changes of CH 3 and CH 3 –N + groups take place first. With increasing temperature, the intensity variation of the CH 2 , C–N, Si–C and C–C groups from the dendritic core is faster than that of the terminal units. This indicates that, with increasing temperature, the segments of the dendritic core obtain enough energy to change their conformation more easily as compared to the terminal units, due to their internal flexibility.

Introducing Multisensor Satellite Radiance-Based Evaluation for Regional Earth System Modeling

Science.gov (United States)

Matsui, T.; Santanello, J.; Shi, J. J.; Tao, W.-K.; Wu, D.; Peters-Lidard, C.; Kemp, E.; Chin, M.; Starr, D.; Sekiguchi, M.;

IR and NMR characterisation of extraction products of radioactively deuteromethylated coals

Energy Technology Data Exchange (ETDEWEB)

Kozlowski, M.; Wachowska, H.; Adriaensens, P.; Gelan, J. [Adam Mickiewicz University, Poznan (Poland). Faculty of Chemistry

1999-12-01

Products of reductive methylation and deuteromethylation of two Polish coals of different rank performed in the potassium/liquid ammonia system were subjected to extraction by dichloromethane. Spectral analysis of the extracts was made. A comparison of {sup 1}H and {sup 2}H NMR spectra indicated that the cleavage of C-C bonds in methylene bridges is of substantial importance for the fragmentation of the coal structure taking place under the effect of potassium in liquid ammonia. This finding was confirmed by results of IR analysis. 25 refs., 3 figs., 2 tabs.

Optical design for a breadboard high-resolution spectrometer for SIRTF/IRS

Science.gov (United States)

Brown, Robert J.; Houck, James R.; van Cleve, Jeffrey E.

1996-11-01

The optical design of a breadboard high resolution infrared spectrometer for the IRS instrument on the SIRTF mission is discussed. The spectrometer uses a crossed echelle grating configuration to cover the spectral region from 10 to 20 micrometer with a resolving power of approximately equals 600. The all reflective spectrometer forms a nearly diffraction limited image of the two dimensional spectrum on a 128 multiplied by 128 arsenic doped silicon area array with 75 micrometer pixels. The design aspects discussed include, grating numerology, image quality, packaging and alignment philosophy.

Solid state linear dichroic infrared spectral analysis of benzimidazoles and their N 1-protonated salts

Science.gov (United States)

Ivanova, B. B.

2005-11-01

A stereo structural characterization of 2,5,6-thrimethylbenzimidazole (MBIZ) and 2-amino-benzimidaziole (2-NH 2-BI) and their N 1 protonation salts was carried out using a polarized solid state linear dichroic infrared spectral (IR-LD) analysis in nematic liquid crystal suspension. All experimental predicted structures were compared with the theoretical ones, obtained by ab initio calculations. The Cs to C2v* symmetry transformation as a result of protonation processes, with a view of its reflection on the infrared spectral characteristics was described.

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

International Nuclear Information System (INIS)

Lane, Ryan A.; Shemmer, Ohad; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

2011-01-01

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 ≤ z ≤ 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame ∼0.1-5 μm spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

Energy Technology Data Exchange (ETDEWEB)

Lane, Ryan A.; Shemmer, Ohad [Department of Physics, University of North Texas, Denton, TX 76203 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Plotkin, Richard M. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam (Netherlands); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A., E-mail: RyanLane@my.unt.edu, E-mail: ohad@unt.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

2011-12-20

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 {<=} z {<=} 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame {approx}0.1-5 {mu}m spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

Accurate and independent spectral response scale based on silicon trap detectors and spectrally invariant detectors

International Nuclear Information System (INIS)

Gran, Jarle

2005-01-01

The study aims to establish an independent high accuracy spectral response scale over a broad spectral range based on standard laboratory equipment at a moderate cost. This had to be done by a primary method, where the responsivity of the detector is linked to fundamental constants. Summary, conclusion and future directions: In this thesis it has been demonstrated that an independent spectral response scale from the visual to the IR based on simple relative measurements can be established. The accuracy obtained by the hybrid self-calibration method demonstrates that state of the art accuracy is obtained with self-calibration principles. A calculable silicon trap detector with low internal losses over a wide spectral range is needed to establish the scale, in addition to a linear, spectrally independent detector with a good signal to noise ratio. By fitting the parameters in the responsivity model to a purely relative measurement we express the spectral response in terms of fundamental constants with a known uncertainty This is therefore a primary method. By applying a digital filter on the relative measurements of the InGaAs detectors in the infrared reduces the standard deviation by 30 %. In addition, by optimising the necessary scaling constant converting the relative calibration to absolute values, we have managed to establish an accurate and cost efficient spectral response scale in the IR. The full covariance analysis, which takes into account the correlation in the absolute values of the silicon detector, the correlation caused by the filter and the scaling constant, shows that the spectral response scale established in the infrared with InGaAs detectors is done with high accuracy. A similar procedure can be used in the UV, though it has not been demonstrated here. In fig. 10 the responsitivities of the detectors (a) and their associated uncertainties (b) at the 1 sigma level of confidence is compared for the three publications. We see that the responsivity

Protonation of benzimidazoles and 1,2,3-benzotriazoles Solid-state linear dichroic infrared (IR-LD) spectral analysis and ab initio calculations

Science.gov (United States)

Ivanova, Bojidarka B.; Pindeva, Liliya I.

2006-09-01

IR-LD spectroscopic data obtained by the orientated solid samples as a suspension in a nematic liquid crystal of 1-hydroxy-1,2,3-benzotriazole, 2-methyl-, 2-acetonitrilebenzimidazoles and their protonated salts have been presented. The stereo-structures have been predicted and compared with theoretical ones. The IR-characteristic bands assignments of all molecule systems have been achieved.

Toward optimal spatial and spectral quality in widefield infrared spectromicroscopy of IR labelled single cells.

Science.gov (United States)

Mattson, Eric C; Unger, Miriam; Clède, Sylvain; Lambert, François; Policar, Clotilde; Imtiaz, Asher; D'Souza, Roshan; Hirschmugl, Carol J

2013-10-07

Advancements in widefield infrared spectromicroscopy have recently been demonstrated following the commissioning of IRENI (InfraRed ENvironmental Imaging), a Fourier Transform infrared (FTIR) chemical imaging beamline at the Synchrotron Radiation Center. The present study demonstrates the effects of magnification, spatial oversampling, spectral pre-processing and deconvolution, focusing on the intracellular detection and distribution of an exogenous metal tris-carbonyl derivative 1 in a single MDA-MB-231 breast cancer cell. We demonstrate here that spatial oversampling for synchrotron-based infrared imaging is critical to obtain accurate diffraction-limited images at all wavelengths simultaneously. Resolution criteria and results from raw and deconvoluted images for two Schwarzschild objectives (36×, NA 0.5 and 74×, NA 0.65) are compared to each other and to prior reports for raster-scanned, confocal microscopes. The resolution of the imaging data can be improved by deconvolving the instrumental broadening that is determined with the measured PSFs, which is implemented with GPU programming architecture for fast hyperspectral processing. High definition, rapidly acquired, FTIR chemical images of respective spectral signatures of the cell 1 and shows that 1 is localized next to the phosphate- and Amide-rich regions, in agreement with previous infrared and luminescence studies. The infrared image contrast, localization and definition are improved after applying proven spectral pre-processing (principal component analysis based noise reduction and RMie scattering correction algorithms) to individual pixel spectra in the hyperspectral cube.

Surface core level shifts of clean and oxygen covered Ir(111)

Energy Technology Data Exchange (ETDEWEB)

Bianchi, M; Cassese, D; Cavallin, A; Comin, R; Orlando, F; Postregna, L [Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Golfetto, E; Baraldi, A [Dipartimento di Fisica e CENMAT, Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Lizzit, S [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste (Italy)], E-mail: alessandro.baraldi@elettra.trieste.it

2009-06-15

We present the results of high resolution core level photoelectron spectroscopy employed to investigate the electronic structure of clean and oxygen covered Ir(111) surface. Ir 4f{sub 7/2} core level spectra are shown to be very sensitive to the local atomic environment. For the clean surface we detected two distinct components shifted by 550 meV, originated by surface and bulk atoms. The larger Gaussian width of the bulk component is explained as due to experimentally unresolved subsurface components. In order to determine the relevance of the phonon contribution we examined the thermal behaviour of the core level lineshape using the Hedin-Rosengren theory. From the phonon-induced spectral broadening we found the Debye temperature of bulk and surface atoms to be 298 and 181 K, respectively, which confirms the softening of the vibrational modes at the surface. Oxygen adsorption leads to the appearance of new surface core level components at -200 meV and +230 meV, which are interpreted as due to first-layer Ir atoms differently coordinated with oxygen. The coverage dependence of these components demonstrates that the oxygen saturation corresponds to 0.38 ML, in good agreement with recent density functional theory calculations.

Dust-deficient Palomar-Green Quasars and the Diversity of AGN Intrinsic IR Emission

Energy Technology Data Exchange (ETDEWEB)

Lyu, Jianwei; Rieke, G. H. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Shi, Yong, E-mail: jianwei@email.arizona.edu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

2017-02-01

To elucidate the intrinsic broadband infrared (IR) emission properties of active galactic nuclei (AGNs), we analyze the spectral energy distributions (SEDs) of 87 z ≲ 0.5 Palomar-Green (PG) quasars. While the Elvis AGN template with a moderate far-IR correction can reasonably match the SEDs of the AGN components in ∼60% of the sample (and is superior to alternatives such as that by Assef), it fails on two quasar populations: (1) hot-dust-deficient (HDD) quasars that show very weak emission thoroughly from the near-IR to the far-IR, and (2) warm-dust-deficient (WDD) quasars that have similar hot dust emission as normal quasars but are relatively faint in the mid- and far-IR. After building composite AGN templates for these dust-deficient quasars, we successfully fit the 0.3–500 μm SEDs of the PG sample with the appropriate AGN template, an infrared template of a star-forming galaxy, and a host galaxy stellar template. 20 HDD and 12 WDD quasars are identified from the SED decomposition, including seven ambiguous cases. Compared with normal quasars, the HDD quasars have AGNs with relatively low Eddington ratios and the fraction of WDD quasars increases with AGN luminosity. Moreover, both the HDD and WDD quasar populations show relatively stronger mid-IR silicate emission. Virtually identical SED properties are also found in some quasars from z = 0.5 to 6. We propose a conceptual model to demonstrate that the observed dust deficiency of quasars can result from a change of structures of the circumnuclear tori that can occur at any cosmic epoch.

On the Spatially Resolved Star Formation History in M51. I. Hybrid UV+IR Star Formation Laws and IR Emission from Dust Heated by Old Stars

Science.gov (United States)

Eufrasio, R. T.; Lehmer, B. D.; Zezas, A.; Dwek, E.; Arendt, R. G.; Basu-Zych, A.; Wiklind, T.; Yukita, M.; Fragos, T.; Hornschemeier, A. E.; Markwardt, L.; Ptak, A.; Tzanavaris, P.

2017-12-01

We present LIGHTNING, a new spectral energy distribution fitting procedure, capable of quickly and reliably recovering star formation history (SFH) and extinction parameters. The SFH is modeled as discrete steps in time. In this work, we assumed lookback times of 0-10 Myr, 10-100 Myr, 0.1-1 Gyr, 1-5 Gyr, and 5-13.6 Gyr. LIGHTNING consists of a fully vectorized inversion algorithm to determine SFH step intensities and combines this with a grid-based approach to determine three extinction parameters. We apply our procedure to the extensive far-UV-to-far-IR photometric data of M51, convolved to a common spatial resolution and pixel scale, and make the resulting maps publicly available. We recover, for M51a, a peak star formation rate (SFR) between 0.1 and 5 Gyr ago, with much lower star formation activity over the past 100 Myr. For M51b, we find a declining SFR toward the present day. In the outskirt regions of M51a, which includes regions between M51a and M51b, we recover an SFR peak between 0.1 and 1 Gyr ago, which corresponds to the effects of the interaction between M51a and M51b. We utilize our results to (1) illustrate how UV+IR hybrid SFR laws vary across M51 and (2) provide first-order estimates for how the IR luminosity per unit stellar mass varies as a function of the stellar age. From the latter result, we find that IR emission from dust heated by stars is not always associated with young stars and that the IR emission from M51b is primarily powered by stars older than 5 Gyr.

Study of transition metal cations state on the catalyst surface by IR-spectroscopy of adsorbed test-molecules (CO, NO)

International Nuclear Information System (INIS)

Davydov, A.A.

1993-01-01

Using the methods of IR spectroscopy and ESR spectral manifestations of CO and NO in complexes with cations of vanadium in different oxidation degrees and coordination states have been studied. V 5+ cations do not coordinate NO and CO, but coordinate ammonia. Regular decrease of νCO values in V n+ -CO complexes with vanadium oxidation degree decrease has been shown. Spectral manifestation of NO complexes with V 4+ and V 3+ have been followed. The formation of V 4+ -NO, V 3+ -NO and V 3+ (NO) complexes has been established

A Sensitivity Study on the Effects of Particle Chemistry, Asphericity and Size on the Mass Extinction Efficiency of Mineral Dust in the Earth's Atmosphere: From the Near to Thermal IR

Science.gov (United States)

Hansell, R. A., Jr.; Reid, J. S.; Tsay, S. C.; Roush, T. L.; Kalashnikova, O. V.

2011-01-01

To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model particle size, while composition is defined by the refractive indices of minerals routinely observed in dust, including the widely used OPAC/Hess parameterization. Single-scattering properties of representative dust particle shapes are calculated using the T-matrix, Discrete Dipole Approximation and Lorenz-Mie light-scattering codes. For the parameterizations examined, MEE ranges from nearly zero to 1.2 square meters per gram, with the higher values associated with non-spheres composed of quartz and gypsum. At near-IR wavelengths, MEE for non-spheres generally exceeds those for spheres, while in the thermal IR, shape-induced changes in MEE strongly depend on volume median diameter (VMD) and wavelength, particularly for MEE evaluated at the mineral resonant frequencies. MEE spectral distributions appear to follow particle geometry and are evidence for shape dependency in the optical properties. It is also shown that non-spheres best reproduce the positions of prominent absorption peaks found in silicates. Generally, angular particles exhibit wider and more symmetric MEE spectral distribution patterns from 8-10 micrometers than those with smooth surfaces, likely due to their edge-effects. Lastly, MEE ratios allow for inferring dust optical properties across the visible-IR spectrum. We conclude the MEE of dust aerosol are significant for the parameter space investigated, and are a key component for remote sensing applications and the study of direct aerosol radiative effects.

Mid-IR Spectra of Refractory Minerals Relevant to Comets

Science.gov (United States)

Jauhari, Shekeab

2008-09-01

On 4 July 2005 the Spitzer Space Telescope obtained mid-IR ( 5-40 µm) spectra of the ejecta from the hypervelocity impact of the Deep Impact projectile with comet 9P/Tempel 1. Spectral modeling demonstrates that there are abundant minerals present in the ejecta including Ca/Fe/Mg-rich silicates, carbonates, phyllosilicates, water ice, amorphous carbon, and sulfides [1]. However, precise mineralogical identifications are hampered by the lack of comprehensive 5 - 40 µm spectral measurements of the emissivity for a broad compositional range of these materials. Here, we present our initial results for 2 - 50 µm transmission spectra and absorption constants for materials relevant to comets, including pyrrhotite, pyrite, and several phyllosilicate (clay) minerals. Measuring the transmission of materials over the full spectral range sensitive by Spitzer requires grinding the minerals into submicron powders and then mixing them with KBr (for the 1-25 um region) and polyethylene (16-50 um region) to form pellets. Transmission measurements of sub-micron sulfides are particularly difficult to obtain because the minerals oxidize rapidly upon grinding and subsequent handling unless special care is taken. A detailed description of our sample preparation and measurement technique will be provided to assist other researchers in their attempts to acquire similar spectra. References: [1] Lisse, C.M. et al., Science 313, 635 - 640 (2006)

Quantitative analysis of semivolatile organic compounds in selected fractions of air sample extracts by GC/MI-IR spectrometry

International Nuclear Information System (INIS)

Childers, J.W.; Wilson, N.K.; Barbour, R.K.

1990-01-01

The authors are currently investigating the capabilities of gas chromatography/matrix isolation infrared (GC/MI-IR) spectrometry for the determination of semivolatile organic compounds (SVOCs) in environmental air sample extracts. Their efforts are focused on the determination of SVOCs such as alkylbenzene positional isomers, which are difficult to separate chromatographically and to distinguish by conventional electron-impact ionization GC/mass spectrometry. They have performed a series of systematic experiments to identify sources of error in quantitative GC/MI-IR analyses. These experiments were designed to distinguish between errors due to instrument design or performance and errors that arise from some characteristic inherent to the GC/MI-IR technique, such as matrix effects. They have investigated repeatability as a function of several aspects of GC/MI IR spectrometry, including sample injection, spectral acquisition, cryogenic disk movement, and matrix deposition. The precision, linearity, dynamic range, and detection limits of a commercial GC/MI-IR system for target SVOCs were determined and compared to those obtained with the system's flame ionization detector. The use of deuterated internal standards in the quantitative GC/MI-IR analysis of selected fractions of ambient air sample extracts will be demonstrated. They will also discuss the current limitations of the technique in quantitative analyses and suggest improvements for future consideration

Detection of metanil yellow contamination in turmeric using FT-Raman and FT-IR spectroscopy

Science.gov (United States)

Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon; Schmidt, Walter; Chan, Dian

2016-05-01

Turmeric is well known for its medicinal value and is often used in Asian cuisine. Economically motivated contamination of turmeric by chemicals such as metanil yellow has been repeatedly reported. Although traditional technologies can detect such contaminants in food, high operational costs and operational complexities have limited their use to the laboratory. This study used Fourier Transform Raman Spectroscopy (FT-Raman) and Fourier Transform - Infrared Spectroscopy (FT-IR) to identify metanil yellow contamination in turmeric powder. Mixtures of metanil yellow in turmeric were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1% and 0.01% (w/w). The FT-Raman and FT-IR spectral signal of pure turmeric powder, pure metanil yellow powder and the 8 sample mixtures were obtained and analyzed independently to identify metanil yellow contamination in turmeric. The results show that FT-Raman spectroscopy and FT-IR spectroscopy can detect metanil yellow mixed with turmeric at concentrations as low as 1% and 5%, respectively, and may be useful for non-destructive detection of adulterated turmeric powder.

Infrared spectral line parameters of HBr and DBr at elevated temperatures

International Nuclear Information System (INIS)

Stocker, R.N.; Goldman, A.

1976-01-01

The electric dipole matrix elements for pure rotation and vibration-rotation transitions, with /m/<=40 and v<=v'<=6, having derived for HBr and DBr by using the Rydberg-Klein-Rees (RKR) potentials and numerical solutions of the Schroedinger equation. An improved dipole-moment expansion was determined by fitting these matrix elements to the available experimental data on line intensities. A least squares analysis of the available line position constants gave an improved set of Dunham coefficients good for spectral lines with both large and small quantum numbers v and J. The results were then used to generate a compilation of individual line parameters for the Δv = 1 bands of HBr and DBr at temperatures up to 3000 K. These parameters, together with previously compiled line parameters for HCl, HF, CO and NO, are being used for line-by-line calculations of radiance from a hot source as seen through an atmospheric path. (author)

A comparison of measured and calculated upwelling radiance over water as a function of sensor altitude

Science.gov (United States)

Coney, T. A.; Salzman, J. A.

1979-01-01

The present paper compares remote sensing data measured over water at altitudes ranging from 30 m to 15.2 km to data calculated for corresponding altitudes using surface measurements and an atmospheric radiative transfer model. The data were acquired on June 22, 1978 in Lake Erie and it was found that suspended solids and chlorophyll concentrations were 0.59 + or - 0.02 mg/liter and 2.42 + or - 0.03 micro gram/liter respectively throughout the duration of the experiment. Calculated and measured nadir radiances for altitudes of 152 m and 12.5 km agree to within 16% and 14% respectively. It is noted that the model offered a poor simulation of the variation in measured radiance with look angle. Finally, it is concluded that an accurate assessment of the source of error will require the inclusion in the analysis of the contributions made by the sea state and specular sky reflectance

Comparison of full-sky polarization and radiance observations to radiative transfer simulations which employ AERONET products.

Science.gov (United States)

Pust, Nathan J; Dahlberg, Andrew R; Thomas, Michael J; Shaw, Joseph A

2011-09-12

Visible-band and near infrared polarization and radiance images measured with a ground-based full-sky polarimeter are compared against a successive orders of scattering (SOS) radiative transfer model for 2009 summer cloud-free days in Bozeman, Montana, USA. The polarimeter measures radiance and polarization in 10-nm bands centered at 450 nm, 490 nm, 530 nm, 630 nm, and 700 nm. AERONET products are used to represent aerosols in the SOS model, while MISR satellite BRF products are used for the surface reflectance. While model results generally agree well with observation, the simulated degree of polarization is typically higher than observed data. Potential sources of this difference may include cloud contamination and/or underestimation of the AERONET-retrieved aerosol real refractive index. Problems with the retrieved parameters are not unexpected given the low aerosol optical depth range (0.025 to 0.17 at 500 nm) during the study and the corresponding difficulties that these conditions pose to the AERONET inversion algorithm.

MODIS/Aqua Clear Radiance Statistics Indexed to Global Grid 5-Min L2 Swath 10km V006

Data.gov (United States)

National Aeronautics and Space Administration — The MODIS/Aqua Clear Radiance Statistics Indexed to Global Grid 5-Min L2 Swath 10km (MYDCSR_G) provides a variety of statistical measures that characterize observed...

The Impact of AMSU-A Radiance Assimilation in the U.S. Navy's Operational Global Atmospheric Prediction System (NOGAPS)

National Research Council Canada - National Science Library

Baker, Nancy L; Hogan, T. F; Campbell, W. F; Pauley, R. L; Swadley, S. D

2005-01-01

...) sensor suite onboard NOAA 15 and 16 for NOGAPS. The direct assimilation of AMSU-A radiances replaced the assimilation of ATOVS temperature retrievals produced by NOAA's National Environmental Satellite, Data and Information Service (NESDIS...

Spectral data based vegetation indices to characterise crop growth parameters and radiation interception in brassica

International Nuclear Information System (INIS)

Kar, G.; Chakravarty, N.V.K.

2001-01-01

Four spectral data based vegetation indices viz., infra-red/red (IR/R) ratio, normalized difference (N.D.), greenness index (GNI) and brightness index (BNI) were derived to characterise leaf area index, above ground biomass production and intercepted photosynthetically active radiation in Brassica oilseed crop. It was found from correlation study among different spectral indices, plant growth parameters and radiation interception that there was strong relationship between infrared/red and normalized difference with green area index for all the three Brassica cultivars whereas these spectral were not significantly correlated with above ground biomass. On the other hand, the brightness and greenness indices were closely correlated with above groundry biomass as compared to infrared/red ratio and normalized difference. All the four spectral indices were correlated with intercepted photosynthetically active radiation (IP AR). The best fit equations relating them were derived, which can be incorporated in the algorithms of crop growth simulation model to estimate plant growth parameters and radiation interception using spectral indices

A UV to mid-IR study of AGN selection

Energy Technology Data Exchange (ETDEWEB)

Chung, Sun Mi; Kochanek, Christopher S. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Assef, Roberto [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Brown, Michael J. I. [School of Physics, Monash University, Clayton, Vic 3800 (Australia); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States); Jannuzi, Buell T. [Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Hickox, Ryan C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Moustakas, John [Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211 (United States)

2014-07-20

We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 deg{sup 2} Boötes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts for ∼20,000 objects, primarily from the AGN and Galaxy Evolution Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are σ/(1 + z) = 0.040 and σ/(1 + z) = 0.169, respectively, with the worst 5% outliers excluded. On the basis of the χ{sub ν}{sup 2} of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I = 23.5 mag. We compare the SED fits for a galaxy-only model and a galaxy-AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGNs, including spatially resolved AGNs with significant contributions from the host galaxy and objects with the emission line ratios of 'composite' spectra. We also use our results to compare with the X-ray, mid-IR, optical color, and emission line ratio selection techniques. For an F-ratio threshold of F > 10, we find 16,266 AGN candidates brighter than I = 23.5 mag and a surface density of ∼1900 AGN deg{sup –2}.

Fully automated dual-frequency three-pulse-echo 2DIR spectrometer accessing spectral range from 800 to 4000 wavenumbers

Energy Technology Data Exchange (ETDEWEB)

Leger, Joel D.; Nyby, Clara M.; Varner, Clyde; Tang, Jianan; Rubtsova, Natalia I.; Yue, Yuankai; Kireev, Victor V.; Burtsev, Viacheslav D.; Qasim, Layla N.; Rubtsov, Igor V., E-mail: irubtsov@tulane.edu [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Rubtsov, Grigory I. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312 (Russian Federation)

2014-08-15

A novel dual-frequency two-dimensional infrared instrument is designed and built that permits three-pulse heterodyned echo measurements of any cross-peak within a spectral range from 800 to 4000 cm{sup −1} to be performed in a fully automated fashion. The superior sensitivity of the instrument is achieved by a combination of spectral interferometry, phase cycling, and closed-loop phase stabilization accurate to ∼70 as. The anharmonicity of smaller than 10{sup −4} cm{sup −1} was recorded for strong carbonyl stretching modes using 800 laser shot accumulations. The novel design of the phase stabilization scheme permits tuning polarizations of the mid-infrared (m-IR) pulses, thus supporting measurements of the angles between vibrational transition dipoles. The automatic frequency tuning is achieved by implementing beam direction stabilization schemes for each m-IR beam, providing better than 50 μrad beam stability, and novel scheme for setting the phase-matching geometry for the m-IR beams at the sample. The errors in the cross-peak amplitudes associated with imperfect phase matching conditions and alignment are found to be at the level of 20%. The instrument can be used by non-specialists in ultrafast spectroscopy.

A research program on radiative transfer model development in support of the ARM program

International Nuclear Information System (INIS)

Clough, S.A.

1993-01-01

The objective of this research effort is to develop radiative transfer models that are consistent with ARM spectral radiance measurements for clear and cloudy atmospheres. Our approach is to develop the model physics and related databases with a line-by-line model in the context of available spectral radiance measurements. The line-by-line model then functions as an intermediate standard to both develop and validate rapid radiative transfer models appropriate to GCM applications. A preprint of an extended abstract for the 1994 AMS volume describing a Quality Measurement Experiment using the ARM spectral data is included as an attachment

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2007-07-28

We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters

Science.gov (United States)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2007-07-01

We report vertical detachment energy (VDE) and IR spectra of Br2•-•(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2•-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150K. A linear relationship is obtained for VDE versus (n+3)-1/3 and bulk VDE of Br2•- aqueous solution is calculated as 10.01eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by ˜0.5eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by ˜6.4eV. Calculated IR spectra show that the formation of Br2•--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2•-•(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Seasonal Surface Spectral Emissivity Derived from Terra MODIS Data

Science.gov (United States)

Sun-Mack, Sunny; Chen, Yan; Minnis, Patrick; Young, DavidF.; Smith, William J., Jr.

2004-01-01

The CERES (Clouds and the Earth's Radiant Energy System) Project is measuring broadband shortwave and longwave radiances and deriving cloud properties form various images to produce a combined global radiation and cloud property data set. In this paper, simultaneous data from Terra MODIS (Moderate Resolution Imaging Spectroradiometer) taken at 3.7, 8.5, 11.0, and 12.0 m are used to derive the skin temperature and the surface emissivities at the same wavelengths. The methodology uses separate measurements of clear sky temperature in each channel determined by scene classification during the daytime and at night. The relationships between the various channels at night are used during the day when solar reflectance affects the 3.7- m radiances. A set of simultaneous equations is then solved to derive the emissivities. Global monthly emissivity maps are derived from Terra MODIS data while numerical weather analyses provide soundings for correcting the observed radiances for atmospheric absorption. These maps are used by CERES and other cloud retrieval algorithms.

Spin orientations of the spin-half Ir(4+) ions in Sr3NiIrO6, Sr2IrO4, and Na2IrO3: Density functional, perturbation theory, and Madelung potential analyses.

Science.gov (United States)

Gordon, Elijah E; Xiang, Hongjun; Köhler, Jürgen; Whangbo, Myung-Hwan

2016-03-21

The spins of the low-spin Ir(4+) (S = 1/2, d(5)) ions at the octahedral sites of the oxides Sr3NiIrO6, Sr2IrO4, and Na2IrO3 exhibit preferred orientations with respect to their IrO6 octahedra. We evaluated the magnetic anisotropies of these S = 1/2 ions on the basis of density functional theory (DFT) calculations including spin-orbit coupling (SOC), and probed their origin by performing perturbation theory analyses with SOC as perturbation within the LS coupling scheme. The observed spin orientations of Sr3NiIrO6 and Sr2IrO4 are correctly predicted by DFT calculations, and are accounted for by the perturbation theory analysis. As for the spin orientation of Na2IrO3, both experimental studies and DFT calculations have not been unequivocal. Our analysis reveals that the Ir(4+) spin orientation of Na2IrO3 should have nonzero components along the c- and a-axis directions. The spin orientations determined by DFT calculations are sensitive to the accuracy of the crystal structures employed, which is explained by perturbation theory analyses when interactions between adjacent Ir(4+) ions are taken into consideration. There are indications implying that the 5d electrons of Na2IrO3 are less strongly localized compared with those of Sr3NiIrO6 and Sr2IrO4. This implication was confirmed by showing that the Madelung potentials of the Ir(4+) ions are less negative in Na2IrO3 than in Sr3NiIrO6 and Sr2IrO4. Most transition-metal S = 1/2 ions do have magnetic anisotropies because the SOC induces interactions among their crystal-field split d-states, and the associated mixing of the states modifies only the orbital parts of the states. This finding cannot be mimicked by a spin Hamiltonian because this model Hamiltonian lacks the orbital degree of freedom, thereby leading to the spin-half syndrome. The spin-orbital entanglement for the 5d spin-half ions Ir(4+) is not as strong as has been assumed.

Solvent-free synthesis of azomethines, spectral correlations and antimicrobial activities of some E-benzylidene-4-chlorobenzenamines

Directory of Open Access Journals (Sweden)

R. Suresh

2015-07-01

Full Text Available Some azomethines including substituted benzylidene-4-chlorobenzenamines (E-imines have been synthesized by fly-ash: PTS catalyzed microwave assisted condensation of 4-chloroaniline and substituted benzaldehydes under solvent-free conditions. The yield of the imines has been found to be more than 85%. The purity of all imines has been checked using their physical constants and UV, IR and NMR spectral data. These spectral data have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral data has been studied. The antimicrobial activities of all imines have been studied using standard methods.

Spectral studies of coordination compounds of cobalt(II) with thiosemicarbazone of heterocyclic ketone

Science.gov (United States)

Chandra, Sulekh; Kumar, Umendra

2005-12-01

The paper presents the spectral analysis of cobalt(II) complexes with indoxyl thiosemicarbazone (ITSC) of general composition [CoL 2X 2] (where L = ITSC, X = Cl -, NO 3-, (1/2)SO 42-, NCS -). The geometry of the complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility measurements and spectral (electronic, IR, EPR, 1H NMR, mass) studies. The various physico-chemical techniques suggested a coordination number of six (octahedral) for chloro, nitrato and thiocyanato complexes. Whereas sulfato complex was found to have five coordinate trigonal-bipyramidal geometry. All the complexes are of high spin type showing magnetic moment corresponding to three unpaired electrons.

Use of INSAT-3D sounder and imager radiances in the 4D-VAR data assimilation system and its implications in the analyses and forecasts

Science.gov (United States)

Indira Rani, S.; Taylor, Ruth; George, John P.; Rajagopal, E. N.

2016-05-01

INSAT-3D, the first Indian geostationary satellite with sounding capability, provides valuable information over India and the surrounding oceanic regions which are pivotal to Numerical Weather Prediction. In collaboration with UK Met Office, NCMRWF developed the assimilation capability of INSAT-3D Clear Sky Brightness Temperature (CSBT), both from the sounder and imager, in the 4D-Var assimilation system being used at NCMRWF. Out of the 18 sounder channels, radiances from 9 channels are selected for assimilation depending on relevance of the information in each channel. The first three high peaking channels, the CO2 absorption channels and the three water vapor channels (channel no. 10, 11, and 12) are assimilated both over land and Ocean, whereas the window channels (channel no. 6, 7, and 8) are assimilated only over the Ocean. Measured satellite radiances are compared with that from short range forecasts to monitor the data quality. This is based on the assumption that the observed satellite radiances are free from calibration errors and the short range forecast provided by NWP model is free from systematic errors. Innovations (Observation - Forecast) before and after the bias correction are indicative of how well the bias correction works. Since the biases vary with air-masses, time, scan angle and also due to instrument degradation, an accurate bias correction algorithm for the assimilation of INSAT-3D sounder radiance is important. This paper discusses the bias correction methods and other quality controls used for the selected INSAT-3D sounder channels and the impact of bias corrected radiance in the data assimilation system particularly over India and surrounding oceanic regions.

Subarcsecond observations of NGC 7538 IRS 1: Continuum distribution and dynamics of molecular gas

Energy Technology Data Exchange (ETDEWEB)

Zhu, Lei; Shi, Hui [National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Zhao, Jun-Hui [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wright, M. C. H. [Department of Astronomy, University of California, Berkeley, Berkeley, CA 94720 (United States); Sandell, Göran [SOFIA-USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, P.O. Box 1, Moffett Field, CA 94035-0001 (United States); Wu, Yue-Fang [Department of Astronomy, Peking University, Beijing 100871 (China); Brogan, Crystal; Corder, Stuartt, E-mail: lzhu@nao.cas.cn [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

2013-12-10

We report new results based on the analysis of the Submillimeter Array (SMA) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of NGC 7538 IRS 1 at 1.3 and 3.4 mm with subarcsecond resolutions. With angular resolutions ∼0.''7, the SMA and CARMA observations show that the continuum emission at 1.3 and 3.4 mm from the hyper-compact H II region IRS 1 is dominated by a compact source with a tail-like extended structure to the southwest of IRS 1. With a CARMA B-array image at 1.3 mm convolved to 0.''1, we resolve the hyper-compact H II region into two components: an unresolved hyper-compact core, and a north-south extension with linear sizes of <270 AU and ∼2000 AU, respectively. The fine structure observed with CARMA is in good agreement with the previous Very Large Array results at centimeter wavelengths, suggesting that the hyper-compact H II region at the center of IRS 1 is associated with an ionized bipolar outflow. We image the molecular lines OCS(19-18) and CH{sub 3}CN(12-11) as well as {sup 13}CO(2-1) surrounding IRS 1, showing a velocity gradient along the southwest-northeast direction. The spectral line profiles in {sup 13}CO(2-1), CO(2-1), and HCN(1-0) observed toward IRS 1 show broad redshifted absorption, providing evidence for gas infall with rates in the range of 3-10 × 10{sup –3} M {sub ☉} yr{sup –1} inferred from our observations.

Theoretical studies of radiative properties of broken clouds

International Nuclear Information System (INIS)

Titov, G.A.

1994-01-01

One of the three goals of the Atmospheric Radiation Measurement (ARM) Program is to improve the quality of radiation models under clear sky, homogeneous cloud, and broken cloud conditions. This report is concerned with the development of the theory of radiation transfer in the broken clouds. Our approach is based on a stochastic description of the interaction between the radiation and cloud field with stochastic geometry; In the following, we discuss (1) the mean radiation fluxes in the near IR spectral range 2.7 to 3.2 μm; (2) the influence of random geometry of individual cumulus clouds on the mean fluxes of visible solar radiation; (3) the equations of the mean radiance in the statistically inhomogeneous cloud fields

Snow Radiance Data Assimilation over High Mountain Asia Using the NASA Land Information System and a Well-Trained Support Vector Machine

Science.gov (United States)

Kwon, Y.; Forman, B. A.; Yoon, Y.; Kumar, S.

2017-12-01

High Mountain Asia (HMA) has been progressively losing ice and snow in recent decades, which could negatively impact regional water supply and native ecosystems. One goal of this study is to characterize the spatiotemporal variability of snow (and ice) across the HMA region. In addition, modeled snow water equivalent (SWE) estimates will be enhanced through the assimilation of passive microwave brightness temperatures (TB) collected by the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) as part of a radiance assimilation system. The radiance assimilation framework includes the NASA Land Information System (LIS) in conjunction with a well-trained support vector machine (SVM) that acts as the observation operator. The Noah Land Surface Model with multi-parameterization options (Noah-MP) is used as the prior model for simulating snow dynamics. Noah-MP is forced by meteorological fields from the NASA Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) atmospheric reanalysis for the periods 01 Sep. 2002 to 01 Sep. 2011. The radiance assimilation system requires two separate phases: 1) training and 2) assimilation. During the training phase, a nonlinear SVM is generated for three different AMSR-E frequencies - 10.65, 18.7, and 36.5 GHz - at both vertical and horizontal polarization. The trained SVM is then used to predict TB during the assimilation phase. An ensemble Kalman filter will be used to condition the model on AMSR-E brightness temperatures not used during SVM training. The performance of the Noah-MP (with and without radiance assimilation) will be assessed via comparison to in-situ measurements, remotely-sensing geophysical retrievals, and other reanalysis products.

Investigation of spectral characteristics of tunnel photodiodes based on DLC nanofilms

Science.gov (United States)

Akchurin, Garif G.; Aban'shin, Nickolay P.; Avetisyan, Yuri A.; Akchurin, Georgy G.; Kochubey, Vyacheslav I.; Yakunin, Alexander N.

2018-04-01

The tunneling photo effect has been studied in a microdiode with an electrostatic field localized at an emitter based on a nanosized DLC structure. It is established the photocurrent, when the carbon nanoemitter is exposed by laser and tunable low-coherent radiation in the spectral range from UV to near IR with photons of low energy (below work function). A linear dependence of the photocurrent on the level of optical power in the range of micro- and milliwatt power is established. The effect of saturation of the current-voltage characteristics of the tunnel photocurrent associated with a finite concentration of non-equilibrium photoelectrons is observed. The observed spectral Watt-Amper characteristics can be adequately interpreted using a modified Fowler-Nordheim equation for non-equilibrium photoelectrons.

Simultaneous retrieval of water vapour, temperature and cirrus clouds properties from measurements of far infrared spectral radiance over the Antarctic Plateau

Science.gov (United States)

Di Natale, Gianluca; Palchetti, Luca; Bianchini, Giovanni; Del Guasta, Massimo

2017-03-01

The possibility separating the contributions of the atmospheric state and ice clouds by using spectral infrared measurements is a fundamental step to quantifying the cloud effect in climate models. A simultaneous retrieval of cloud and atmospheric parameters from infrared wideband spectra will allow the disentanglement of the spectral interference between these variables. In this paper, we describe the development of a code for the simultaneous retrieval of atmospheric state and ice cloud parameters, and its application to the analysis of the spectral measurements acquired by the Radiation Explorer in the Far Infrared - Prototype for Applications and Development (REFIR-PAD) spectroradiometer, which has been in operation at Concordia Station on the Antarctic Plateau since 2012. The code performs the retrieval with a computational time that is comparable with the instrument acquisition time. Water vapour and temperature profiles and the cloud optical and microphysical properties, such as the generalised effective diameter and the ice water path, are retrieved by exploiting the 230-980 cm-1 spectral band. To simulate atmospheric radiative transfer, the Line-By-Line Radiative Transfer Model (LBLRTM) has been integrated with a specifically developed subroutine based on the δ-Eddington two-stream approximation, whereas the single-scattering properties of cirrus clouds have been derived from a database for hexagonal column habits. In order to detect ice clouds, a backscattering and depolarisation lidar, co-located with REFIR-PAD has been used, allowing us to infer the position and the cloud thickness to be used in the retrieval. A climatology of the vertical profiles of water vapour and temperature has been performed by using the daily radiosounding available at the station at 12:00 UTC. The climatology has been used to build an a priori profile correlation to constrain the fitting procedure. An optimal estimation method with the Levenberg-Marquardt approach has been

Developing Wide-Field Spatio-Spectral Interferometry for Far-Infrared Space Applications

Science.gov (United States)

Leisawitz, David; Bolcar, Matthew R.; Lyon, Richard G.; Maher, Stephen F.; Memarsadeghi, Nargess; Rinehart, Stephen A.; Sinukoff, Evan J.

2012-01-01

Interferometry is an affordable way to bring the benefits of high resolution to space far-IR astrophysics. We summarize an ongoing effort to develop and learn the practical limitations of an interferometric technique that will enable the acquisition of high-resolution far-IR integral field spectroscopic data with a single instrument in a future space-based interferometer. This technique was central to the Space Infrared Interferometric Telescope (SPIRIT) and Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) space mission design concepts, and it will first be used on the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII). Our experimental approach combines data from a laboratory optical interferometer (the Wide-field Imaging Interferometry Testbed, WIIT), computational optical system modeling, and spatio-spectral synthesis algorithm development. We summarize recent experimental results and future plans.

Evidence of non-LTE Effects in Mesospheric Water Vapor from Spectrally-Resolved Emissions Observed by CIRRIS-1A

Science.gov (United States)

Zhou, D. K.; Mlynczak, M. G.; Lopez-Puertas, M.; Zaragoza, G.

1999-01-01

Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality, atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010 to 000) and (020 to 010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O2 in the mesosphere. An exchange rate of 1.2 x 10(exp -12)cc/s is derived.

Drift and transmission FT-IR spectroscopy of forest soils: an approach to determine decomposition processes of forest litter

International Nuclear Information System (INIS)

Haberhauer, G.; Gerzabek, M.H.

1999-06-01

A method is described to characterize organic soil layers using Fourier transformed infrared spectroscopy. The applicability of FT-IR, either dispersive or transmission, to investigate decomposition processes of spruce litter in soil originating from three different forest sites in two climatic regions was studied. Spectral information of transmission and diffuse reflection FT-IR spectra was analyzed and compared. For data evaluation Kubelka Munk (KM) transformation was applied to the DRIFT spectra. Sample preparation for DRIFT is simpler and less time consuming in comparison to transmission FT-IR, which uses KBr pellets. A variety of bands characteristics of molecular structures and functional groups has been identified for these complex samples. Analysis of both transmission FT-IR and DRIFT, showed that the intensity of distinct bands is a measure of the decomposition of forest litter. Interferences due to water adsorption spectra were reduced by DRIFT measurement in comparison to transmission FT-IR spectroscopy. However, data analysis revealed that intensity changes of several bands of DRIFT and transmission FT-IR were significantly correlated with soil horizons. The application of regression models enables identification and differentiation of organic forest soil horizons and allows to determine the decomposition status of soil organic matter in distinct layers. On the basis of the data presented in this study, it may be concluded that FT-IR spectroscopy is a powerful tool for the investigation of decomposition dynamics in forest soils. (author)

Multivariat least-squares methods applied to the quantitative spectral analysis of multicomponent samples

International Nuclear Information System (INIS)

Haaland, D.M.; Easterling, R.G.; Vopicka, D.A.

1985-01-01

In an extension of earlier work, weighted multivariate least-squares methods of quantitative FT-IR analysis have been developed. A linear least-squares approximation to nonlinearities in the Beer-Lambert law is made by allowing the reference spectra to be a set of known mixtures, The incorporation of nonzero intercepts in the relation between absorbance and concentration further improves the approximation of nonlinearities while simultaneously accounting for nonzero spectra baselines. Pathlength variations are also accommodated in the analysis, and under certain conditions, unknown sample pathlengths can be determined. All spectral data are used to improve the precision and accuracy of the estimated concentrations. During the calibration phase of the analysis, pure component spectra are estimated from the standard mixture spectra. These can be compared with the measured pure component spectra to determine which vibrations experience nonlinear behavior. In the predictive phase of the analysis, the calculated spectra are used in our previous least-squares analysis to estimate sample component concentrations. These methods were applied to the analysis of the IR spectra of binary mixtures of esters. Even with severely overlapping spectral bands and nonlinearities in the Beer-Lambert law, the average relative error in the estimated concentration was <1%

Pulse Shaping for High Capacity Impulse Radio Ultra-Wideband Wireless Links Under the Russian Spectral Emission Mask

DEFF Research Database (Denmark)

Grakhova, Elizaveta P.; Rommel, Simon; Jurado-Navas, Antonio

2016-01-01

Two pulse shapes for IR-UWB transmission under the Russian spectral emission mask are proposed and their potential experimentally demonstrated. Pulses based on the hyperbolic secant square function and the frequency B-spline wavelet are shown to enable transmission of 1.25 Gbit/s signals, reaching...

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

KAUST Repository

Wu, B. L.

2013-10-10

Effect of antiferromagnet on superconductivity has been investigated in IrMn/Nb bilayers. Significant suppression of both transition temperature (Tc) and lower critical field (Hc1) of Nb is found in IrMn/Nb bilayers as compared to a single layer Nb of same thickness; the suppression effect is even stronger than that of a ferromagnet in NiFe/Nb bilayers. The addition of an insulating MgO layer at the IrMn-Nb interface nearly restores Tc to that of the single layer Nb, but Hc1 still remains suppressed. These results suggest that, in addition to proximity effect and magnetic impurity scattering, magnetostatic interaction also plays a role in suppressing superconductivity of Nb in IrMn/Nb bilayers. In addition to reduced Tc and Hc1, the IrMn layer also induces broadening in the transition temperature of Nb, which can be accounted for by a finite distribution of stray field from IrMn.

Isolation and Spectral Analysis of Naturally Occurring Thiarubrine A

Science.gov (United States)

Reyes, Juan; Morton, Melita; Downum, Kelsey; O'Shea, Kevin E.

2001-06-01

We have designed an experiment in which students isolate and characterize thiarubrine A, a pseudo-antiaromatic 1,2-dithia-3,5-cyclohexadiene derivative. Thiarubrines are an important class of compounds which have recently received attention because of their unusual reactivity, unique biological activity, and potential medicinal applications. They possess a distinctive red color and structure features that are particularly useful for demonstrating UV-vis, NMR, and IR spectral analyses. A crude mixture containing thiarubrine A is obtained by methanol (liquid-solid) extraction of the roots of short ragweed, Ambrosia artemisiifolia. Alternatively, these compounds can be isolated from numerous taxa within the family Asteraceae. Thiarubrine A possesses alkyl, alkenyl, and alkynyl functionality, which is useful in illustrating the utility of IR and NMR in the characterization of natural products. The long wavelength UV-vis absorption band of thiarubrine is indication of the nonplanarity of dithiin ring and provides an excellent opportunity to discuss the concepts of aromaticity, conjugation, and molecular orbital theory.

Surface roughness considerations for atmospheric correction of ocean color sensors. I - The Rayleigh-scattering component. II - Error in the retrieved water-leaving radiance

Science.gov (United States)

Gordon, Howard R.; Wang, Menghua

1992-01-01

The first step in the Coastal Zone Color Scanner (CZCS) atmospheric-correction algorithm is the computation of the Rayleigh-scattering (RS) contribution, L sub r, to the radiance leaving the top of the atmosphere over the ocean. In the present algorithm, L sub r is computed by assuming that the ocean surface is flat. Calculations of the radiance leaving an RS atmosphere overlying a rough Fresnel-reflecting ocean are presented to evaluate the radiance error caused by the flat-ocean assumption. Simulations are carried out to evaluate the error incurred when the CZCS-type algorithm is applied to a realistic ocean in which the surface is roughened by the wind. In situations where there is no direct sun glitter, it is concluded that the error induced by ignoring the Rayleigh-aerosol interaction is usually larger than that caused by ignoring the surface roughness. This suggests that, in refining algorithms for future sensors, more effort should be focused on dealing with the Rayleigh-aerosol interaction than on the roughness of the sea surface.

Rapid determination and chemical change tracking of benzoyl peroxide in wheat flour by multi-step IR macro-fingerprinting

Science.gov (United States)

Guo, Xiao-Xi; Hu, Wei; Liu, Yuan; Sun, Su-Qin; Gu, Dong-Chen; He, Helen; Xu, Chang-Hua; Wang, Xi-Chang

2016-02-01

BPO is often added to wheat flour as flour improver, but its excessive use and edibility are receiving increasing concern. A multi-step IR macro-fingerprinting was employed to identify BPO in wheat flour and unveil its changes during storage. BPO contained in wheat flour (treatment of BPO in wheat flour based on 2DCOS-IR and spectral subtraction analysis, it was found that BPO in wheat flour not only decomposed into benzoic acid and benzoate, but also produced other deleterious substances, e.g., benzene. This study offers a promising method with minimum pretreatment and time-saving to identify BPO in wheat flour and its chemical products during storage in a holistic manner.

Synthesis, spectral and photophysical properties of novel phthalocyanines bearing bulky phenantroxy moiety

International Nuclear Information System (INIS)

Erdogmuş, Ali; Lütfi Ugur, Ahmet; Memişoglu, Abdussamed; Erden, İbrahim

2013-01-01

The synthesis, characterization, spectral and photophysical properties of soluble 9-Phenanthroxy substituted oxo-titanium (IV), zinc, magnesium and nickel phthalocyanines (1a, 1b, 1c and 1d) are reported for the first time. The new compounds have been characterized by elemental analysis, FT-IR, 1 H–NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for spectral, fluorescence properties and fluorescence quantum yields of these compounds in dimethylsulfoxide (DMSO) and toluene. All phthalocyanine complexes (1a to 1d) exhibited excellent solubility in organic solvents such as dichloromethane, chloroform, THF, toluene, DMF and DMSO. - Highlights: ► New metallophthalocyanines (1a–1d) were synthesized. ► These new phthalocyanine derivatives show the enhanced solubility in organic solvents. ► The spectral and photophysical properties of TiO(IV), zinc (II) and Mg(II) phthalocyanine (1a–1c) are investigated in DMSO and toluene. ► Ground state electronic absorption and fluorescence spectra.

Exchange, x-ray and IR spectral behaviour of lanthanum and praseodymium exchanged zeolite X

International Nuclear Information System (INIS)

Das, D.; Upreti, M.C.

1995-01-01

Exchange behaviour of lanthanum and praseodymium ions in zeolite X involves three steps: preferential exchange, intrazeolitic exchange and irreversible exchange. At room temperature , higher exchange has been observed with La(III) than with Pr(III) which is attributed to the smaller hydrosphere of lanthanum than praseodymium. IR spectra of these zeolites in KBr pellets show a shift in the major Si-O stretching vibration of 972 cm -1 to higher frequencies. Their x-ray diffraction patterns remain unchanged except a large decrease of the line intensities caused by the absorption of x-rays by heavy La(III) and Pr(III) ions. The present study reports the preparation and physicochemical properties of lanthanum and praseodymium exchanged zeolite X. (author). 12 refs., 3 figs., 3 tabs

Differentiation of Body Fluid Stains on Fabrics Using External Reflection Fourier Transform Infrared Spectroscopy (FT-IR) and Chemometrics.

Science.gov (United States)

Zapata, Félix; de la Ossa, Ma Ángeles Fernández; García-Ruiz, Carmen

2016-04-01

Body fluids are evidence of great forensic interest due to the DNA extracted from them, which allows genetic identification of people. This study focuses on the discrimination among semen, vaginal fluid, and urine stains (main fluids in sexual crimes) placed on different colored cotton fabrics by external reflection Fourier transform infrared spectroscopy (FT-IR) combined with chemometrics. Semen-vaginal fluid mixtures and potential false positive substances commonly found in daily life such as soaps, milk, juices, and lotions were also studied. Results demonstrated that the IR spectral signature obtained for each body fluid allowed its identification and the correct classification of unknown stains by means of principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Interestingly, results proved that these IR spectra did not show any bands due to the color of the fabric and no substance of those present in daily life which were analyzed, provided a false positive. © The Author(s) 2016.

Analyzing Black Hole Super-Radiance Emission of Particles/Energy from a Black Hole as a Gedankenexperiment to Get Bounds on the Mass of a Graviton

Directory of Open Access Journals (Sweden)

A. Beckwith

2014-01-01

Full Text Available Use of super-radiance in BH physics, so dE/dt<0 specifies conditions for a mass of a graviton being less than or equal to 1065 grams, allows for determing what role additional dimensions may play in removing the datum that massive gravitons lead to 3/4th the bending of light past the planet Mercury. The present document makes a given differentiation between super-radiance in the case of conventional BHs and Braneworld BH super-radiance, which may delineate whether Braneworlds contribute to an admissible massive graviton in terms of removing the usual problem of the 3/4th the bending of light past the planet Mercury which is normally associated with massive gravitons. This leads to a fork in the road between two alternatives with the possibility of needing a multiverse containment of BH structure or embracing what Hawkings wrote up recently, namely, a redo of the event horizon hypothesis as we know it.

Rapid, nondestructive estimation of surface polymer layer thickness using attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy and synthetic spectra derived from optical principles.

Science.gov (United States)

Weinstock, B André; Guiney, Linda M; Loose, Christopher

2012-11-01

We have developed a rapid, nondestructive analytical method that estimates the thickness of a surface polymer layer with high precision but unknown accuracy using a single attenuated total reflection Fourier transform infrared (ATR FT-IR) measurement. Because the method is rapid, nondestructive, and requires no sample preparation, it is ideal as a process analytical technique. Prior to implementation, the ATR FT-IR spectrum of the substrate layer pure component and the ATR FT-IR and real refractive index spectra of the surface layer pure component must be known. From these three input spectra a synthetic mid-infrared spectral matrix of surface layers 0 nm to 10,000 nm thick on substrate is created de novo. A minimum statistical distance match between a process sample's ATR FT-IR spectrum and the synthetic spectral matrix provides the thickness of that sample. We show that this method can be used to successfully estimate the thickness of polysulfobetaine surface modification, a hydrated polymeric surface layer covalently bonded onto a polyetherurethane substrate. A database of 1850 sample spectra was examined. Spectrochemical matrix-effect unknowns, such as the nonuniform and molecularly novel polysulfobetaine-polyetherurethane interface, were found to be minimal. A partial least squares regression analysis of the database spectra versus their thicknesses as calculated by the method described yielded an estimate of precision of ±52 nm.

Monitoring combat wound healing by IR hyperspectral imaging

Science.gov (United States)

Howle, Chris R.; Spear, Abigail M.; Gazi, Ehsan; Crane, Nicole J.

2016-03-01

In recent conflicts, battlefield injuries consist largely of extensive soft injuries from blasts and high energy projectiles, including gunshot wounds. Repair of these large, traumatic wounds requires aggressive surgical treatment, including multiple surgical debridements to remove devitalised tissue and to reduce bacterial load. Identifying those patients with wound complications, such as infection and impaired healing, could greatly assist health care teams in providing the most appropriate and personalised care for combat casualties. Candidate technologies to enable this benefit include the fusion of imaging and optical spectroscopy to enable rapid identification of key markers. Hence, a novel system based on IR negative contrast imaging (NCI) is presented that employs an optical parametric oscillator (OPO) source comprising a periodically-poled LiNbO3 (PPLN) crystal. The crystal operates in the shortwave and midwave IR spectral regions (ca. 1.5 - 1.9 μm and 2.4 - 3.8 μm, respectively). Wavelength tuning is achieved by translating the crystal within the pump beam. System size and complexity are minimised by the use of single element detectors and the intracavity OPO design. Images are composed by raster scanning the monochromatic beam over the scene of interest; the reflection and/or absorption of the incident radiation by target materials and their surrounding environment provide a method for spatial location. Initial results using the NCI system to characterise wound biopsies are presented here.

Qualitative infrared spectral analysis of products adsorbed by silica gel from ditolylmethane coolant and their adsorption isotherm

International Nuclear Information System (INIS)

Ermakov, V.A.; Benderskaya, O.S.

1987-01-01

The IR-spectral analysis has been applied to study the products adsorbed from ditolylmethane first-circuit coolant, as well as from still bottoms after coolant distillation on silicagel of various makes. The qualitative study of desorbate IR-spectra has shown that they refer to the classes of arylaldehydes, diarylketones and carbonic acids. Under actual conditions first-circuit reactor coolant also has a wide set of products of its radiolysis, therefore the spectrum of coolant oxidaton products must be wider. It is noted that adsorption on silica gel, ASK of oxygen-bearing compounds which are present in ditolyl methane coolant has 2 stages

The Need Of A Phenological Spectral Library Of Submersed Macrophytes For Lake Monitoring

Science.gov (United States)

Wolf, Patrick; Robler, Sebastian; Schneider, Thomas; Melzer, Arnulf

2013-12-01

Submersed macrophytes are bio-indicators for water quality. For plant monitoring by remote sensing, in-situ reflectance measurements are necessary. Hence, systematic measurements were carried out at Lake Starnberg and Lake Tegernsee (Germany) in the year 2011. Besides two wide-spread species (Chara spp. and Potamogeton perfoliatus), the invasive species Elodea nuttallii and Najas marina were investigated. Remote sensing reflectances were calculated from downwelling irradiance and upwelling radiance. Those were collected with RAMSES spectroradiometers (320nm-950nm, 3.3nm step). As data collection took place several times, changes in the spectral responses within the growing season were detected and could be linked to population density, growing height, biomass and pigmentation. Additionally, a stable sampling method and a processing chain for the in-situ reflectance measurements were developed. Part of the processing was a water column correction, including WASI (water colour simulator). Principal component analysis showed separability of sediment from vegetation and species differentiation.

Spectral mixture analysis for water quality assessment over the Amazon floodplain using Hyperion/EO-1 images

Directory of Open Access Journals (Sweden)

Lênio Soares Galvão

2006-12-01

Full Text Available Water composition undergoes complex spatial and temporal variations throughout the central Amazon floodplain. This study analyzed the spectral mixtures of the optically active substances (OASs in water with spaceborne hyperspectral images. The test site was located upstream the confluence of Amazon (white water and Tapajós (clear-water rivers, where two Hyperion images were acquired from the Earth Observing One (EO-1 satellite. The first image was acquired on September 16, 2001, during the falling water period of the Amazon River. The second image was acquired on June 23, 2005, at the end of the high water period. The images were pre-processed to remove stripes of anomalous pixels, convert radiance-calibrated data to surface reflectance, mask land, clouds and macrophytes targets, and spectral subset the data within the range of 457-885nm. A sequential procedure with the techniques Minimum Noise Fraction (MNF, Pixel Purity Index (PPI and n-dimensional visualization of the MNF feature space was employed to select end-members from both images. A single set of end-members was gathered to represent the following spectrally unique OASs: clear-water; dissolved organic matter; suspended sediments; and phytoplankton. The Linear Spectral Unmixing algorithm was applied to each Hyperion image in order to map the spatial distribution of these constituents, in terms of sub-pixel fractional abundances. Results showed three patterns of changes in the water quality from high to falling flood periods: decrease of suspended inorganic matter concentration in the Amazon River; increase of suspended inorganic matter and phytoplankton concentrations in varzea lakes; and increase of phytoplankton concentration in the Tapajós River.

Spectral mixture analysis for water quality assessment over the Amazon floodplain using Hyperion/EO-1 images

Directory of Open Access Journals (Sweden)

Lênio Soares Galvão

2007-06-01

Full Text Available Water composition undergoes complex spatial and temporal variations throughout the central Amazon floodplain. This study analyzed the spectral mixtures of the optically active substances (OASs in water with spaceborne hyperspectral images. The test site was located upstream the confluence of Amazon (white water and Tapajós (clear-water rivers, where two Hyperion images were acquired from the Earth Observing One (EO-1 satellite. The first image was acquired on September 16, 2001, during the falling water period of the Amazon River. The second image was acquired on June 23, 2005, at the end of the high water period. The images were pre-processed to remove stripes of anomalous pixels, convert radiance-calibrated data to surface reflectance, mask land, clouds and macrophytes targets, and spectral subset the data within the range of 457-885nm. A sequential procedure with the techniques Minimum Noise Fraction (MNF, Pixel Purity Index (PPI and n-dimensional visualization of the MNF feature space was employed to select end-members from both images. A single set of end-members was gathered to represent the following spectrally unique OASs: clear-water; dissolved organic matter; suspended sediments; and phytoplankton. The Linear Spectral Unmixing algorithm was applied to each Hyperion image in order to map the spatial distribution of these constituents, in terms of sub-pixel fractional abundances. Results showed three patterns of changes in the water quality from high to falling flood periods: decrease of suspended inorganic matter concentration in the Amazon River; increase of suspended inorganic matter and phytoplankton concentrations in varzea lakes; and increase of phytoplankton concentration in the Tapajós River.

Thermal structure of the Martian atmosphere retrieved from the IR- spectrometry in the 15 mkm CO2 band

Science.gov (United States)

Zasova, L.; Formisano, V.; Grassi, D.; Igantiev, N.; Moroz, V.

Thermal IR spectrometry is one of the methods of the Martian atmosphere investigation below 55 km. The temperature profiles retrieved from the 15 μm CO2 band may be used for MIRA database. This approach gives the vertical resolution of several kilometers and accuracy of several Kelvins. An aerosol abundance, which influences the temperature profiles, is obtained from the continuum of the same spectrum. It is taken into account in the temperature retrieval procedure in a self- consistent way. Although this method has limited vertical resolution it possesses some advantages. For example, the radio occultation method gives the temperature profiles with higher spectral resolution, but the radio observations are sparse in space and local time. Direct measurements, which give the most accurate results, enable to obtain the temperature profiles only for some chosen points (landing places). Actually, the thermal IR-spectrometry is the only method, which allows to monitor the temperature profiles with good coverage both in space and local time. The first measurements of this kind were fulfilled by IRIS, installed on board of Mariner 9. This spectrometer was characterized by rather high spectral resolution (2.4 cm-1). The temperature profiles vs. local time dependencies for different latitudes and seasons were retrieved, including dust storm conditions, North polar night, Tharsis volcanoes. The obtained temperature profiles have been compared with the temperature profiles for the same conditions, taken from Climate Data Base (European GCM). The Planetary Fourier Spectrometer onboard Mars Express (which is planned to be launched in 2003) has the spectral range 1.2-45 μm and spectral resolution of 1.5 cm- 1. Temperature retrieval is one of the main scientific goals of the experiment. It opens a possibility to get a series of temperature profiles taken for different conditions, which can later be used in MIRA producing.

Spectrally- and Time-Resolved Sum Frequency Generation (STiR-SFG): a new tool for ultrafast hydrogen bond dynamics at interfaces.

Science.gov (United States)

Benderskii, Alexander; Bordenyuk, Andrey; Weeraman, Champika

2006-03-01

The recently developed spectrally- and time-resolved Sum Frequency Generation (STiR-SFG) is a surface-selective 3-wave mixing (IR+visible) spectroscopic technique capable of measuring ultrafast spectral evolution of vibrational coherences. A detailed description of this measurement will be presented, and a noniterative method or deconvolving the laser pulses will be introduced to obtain the molecular response function. STiR-SFG, combined with the frequency-domain SFG spectroscopy, was applied to study hydrogen bonding dynamics at aqueous interfaces (D2O/CaF2). Spectral dynamics of the OD-stretch on the 50-150 fs time scale provides real-time observation of ultrafast H-bond rearrangement. Tuning the IR wavelength to the blue or red side of the OD-stretch transition, we selectively monitor the dynamics of different sub-ensembles in the distribution of the H-bond structures. The blue-side excitation (weaker H-bonding) shows monotonic red-shift of the OD-frequency. In contrast, the red-side excitation (stronger H-bonding structures) produces a blue-shift and a recursion, which may indicate the presence of an underdamped intermolecular mode of interfacial water. Effect of electrolyte concentration on the H-bond dynamics will be discussed.

Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

Energy Technology Data Exchange (ETDEWEB)

Yang, Hui; Huang, Chao; Yang, Fan [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Du, Li [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China)

2015-12-01

Graphical abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction caused by the addition of Ir. - Highlights: • Mesoporous nanoparticles were synthesized and used as support for metal catalyst. • PdIr bimetallic catalyst exhibited significantly improved hydrogenation activity. • The strong promotion of Ir was recognized firstly and investigated intensively. • PdIr exhibits 18 times higher activity than Pd to the hydrogenation of nitrobenzene. - Abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction

Ngc7538 Irs1 - A Highly Collimated Ionized Wind Source Powered By Accretion

Science.gov (United States)

Sandell, Goran H. L.; Wright, M.; Goss, W.; Corder, S.

2009-01-01

Recent images show that NGC7538 IRS1 is not a conventional Ultracompact or Hypercompact HII region, but is completely wind-excited (other broad recombination line hypercompact HII regions may be similar to IRS1). NGC 7538 IRS1 is a well studied young high-mass star (L 2 10^5 L_Sun).VLA images at 6 and 2 cm (Cambell 1984; ApJ, 282, L27) showed a compact bipolar core (lobe separation 0.2") with more extended faint lobes. Recombination line observations (Gaume et al. 1995, ApJ, 438, 776) show extremely wide line profiles indicating substantial mass motion of the ionized gas. We re-analyzed high angular resolution VLA archive data from 6 cm to 7 mm, and measured the flux from the compact core and the extended (1.5 - 2") bipolar lobes. We find that the compact core has a spectral index, alpha 0.6, which could be explained by an optically thick hypercompact core with a density gradient. However, the size of the core shrinks with increasing frequency; from 0.24" at 6 cm to 0.1" at 7 mm, consistent with that expected for a collimated jet (Reynolds 1986, ApJ, 304, 713). If we do a crude size correction so that we compare emission from the optically thick inner part of the jet for a set of 2 cm and 7 mm observations we get alpha 1.6, i.e. close to the optically thick value. BIMA and CARMA continuum observations at 3 mm show some dust excess, while. HCO+ J=1-0 observations combined with FCRAO single dish data show a clear inverse P Cygni profile towards IRS1. These observations confirm that IRS1 is heavily accreting with an accretion rate 2 10^-4 M_Sun/year, sufficient to quench the formation of an HII region.

BOOTES-IR: near IR follow-up GRB observations by a robotic system

International Nuclear Information System (INIS)

Castro-Tirado, A.J.; Postrigo, A. de Ugarte; Jelinek, M.

2005-01-01

BOOTES-IR is the extension of the BOOTES experiment, which operates in Southern Spain since 1998, to the near IR (NIR). The goal is to follow up the early stage of the gamma ray burst (GRB) afterglow emission in the NIR, alike BOOTES does already at optical wavelengths. The scientific case that drives the BOOTES-IR performance is the study of GRBs with the support of spacecraft like INTEGRAL, SWIFT and GLAST. Given that the afterglow emission in both, the NIR and the optical, in the instances immediately following a GRB, is extremely bright (reached V = 8.9 in one case), it should be possible to detect this prompt emission at NIR wavelengths too. The combined observations by BOOTES-IR and BOOTES-1 and BOOTES-2 will allow for real time identification of trustworthy candidates to have a high redshift (z > 5). It is expected that, few minutes after a GRB, the IR magnitudes be H ∼ 7-10, hence very high quality spectra can be obtained for objects as far as z = 10 by larger instruments

Development of Cytoplasmic Male Sterile IR24 and IR64 Using CW-CMS/Rf17 System.

Science.gov (United States)

Toriyama, Kinya; Kazama, Tomohiko

2016-12-01

A wild-abortive-type (WA) cytoplasmic male sterility (CMS) has been almost exclusively used for breeding three-line hybrid rice. Many indica cultivars are known to carry restorer genes for WA-CMS lines and cannot be used as maintainer lines. Especially elite indica cultivars IR24 and IR64 are known to be restorer lines for WA-CMS lines, and are used as male parents for hybrid seed production. If we develop CMS IR24 and CMS IR64, the combination of F1 pairs in hybrid rice breeding programs will be greatly broadened. For production of CMS lines and restorer lines of IR24 and IR64, we employed Chinese wild rice (CW)-type CMS/Restorer of fertility 17 (Rf17) system, in which fertility is restored by a single nuclear gene, Rf17. Successive backcrossing and marker-assisted selection of Rf17 succeeded to produce completely male sterile CMS lines and fully restored restorer lines of IR24 and IR64. CW-cytoplasm did not affect agronomic characteristics. Since IR64 is one of the most popular mega-varieties and used for breeding of many modern varieties, the CW-CMS line of IR64 will be useful for hybrid rice breeding.

Investigation of radiant millimeter wave/terahertz radiation from low-infrared signature targets

Science.gov (United States)

Aytaç, B.; Alkuş, Ü.; Sivaslıgil, M.; Şahin, A. B.; Altan, H.

2017-10-01

Millimeter (mm) and sub-mm wave radiation is increasingly becoming a region of interest as better methods are developed to detect in this wavelength range. The development of sensitive focal plane array (FPA) architectures as well as single pixel scanners has opened up a new field of passive detection and imaging. Spectral signatures of objects, a long standing area of interest in the Short Wave Infrared (SWIR), Mid-Wave (MWIR) and Long Wave-IR (LWIR) bands can now be assessed in the mm-wave/terahertz (THz) region. The advantage is that this form of radiation is not as adversely affected by poor atmospheric conditions compared to other bands. In this study, a preliminary experiment in a laboratory environment is performed to assess the radiance from targets with low infrared signatures in the millimeter wave/terahertz (THz) band (<1 THz). The goal of this approach is to be able to model the experimental results to better understand the mm-wave/THz signature of targets with low observability in the IR bands.

The TApIR experiment. IR absorption spectra of liquid hydrogen isotopologues

International Nuclear Information System (INIS)

Groessle, Robin

2015-01-01

The scope of the thesis is the infrared absorption spectroscopy of liquid hydrogen isotopologues with the tritium absorption infrared spectroscopy (TApIR) experiment at the tritium laboratory Karlsruhe (TLK). The calibration process from the sample preparation to the reference measurements are described. A further issue is the classical evaluation of FTIR absorption spectra and the extension using the rolling circle filter (RCF) including the effects on statistical and systematical errors. The impact of thermal and nuclear spin temperature on the IR absorption spectra is discussed. An empirical based modeling for the IR absorption spectra of liquid hydrogen isotopologues is performed.

New impressive capabilities of SE-workbench for EO/IR real-time rendering of animated scenarios including flares

Science.gov (United States)

Le Goff, Alain; Cathala, Thierry; Latger, Jean

2015-10-01

To provide technical assessments of EO/IR flares and self-protection systems for aircraft, DGA Information superiority resorts to synthetic image generation to model the operational battlefield of an aircraft, as viewed by EO/IR threats. For this purpose, it completed the SE-Workbench suite from OKTAL-SE with functionalities to predict a realistic aircraft IR signature and is yet integrating the real-time EO/IR rendering engine of SE-Workbench called SE-FAST-IR. This engine is a set of physics-based software and libraries that allows preparing and visualizing a 3D scene for the EO/IR domain. It takes advantage of recent advances in GPU computing techniques. The recent past evolutions that have been performed concern mainly the realistic and physical rendering of reflections, the rendering of both radiative and thermal shadows, the use of procedural techniques for the managing and the rendering of very large terrains, the implementation of Image- Based Rendering for dynamic interpolation of plume static signatures and lastly for aircraft the dynamic interpolation of thermal states. The next step is the representation of the spectral, directional, spatial and temporal signature of flares by Lacroix Defense using OKTAL-SE technology. This representation is prepared from experimental data acquired during windblast tests and high speed track tests. It is based on particle system mechanisms to model the different components of a flare. The validation of a flare model will comprise a simulation of real trials and a comparison of simulation outputs to experimental results concerning the flare signature and above all the behavior of the stimulated threat.

Synthesis and Spectral Evaluation of Some Unsymmetrical Mesoporphyrinic Complexes

Directory of Open Access Journals (Sweden)

Rica Boscencu

2012-06-01

Full Text Available Synthesis and spectral evaluation of new zinc and copper unsymmetrical mesoporphyrinic complexes are reported. Zn(II-5-(4-acetoxy-3-methoxyphenyl-10,15,20-tris-(4-carboxymethylphenylporphyrin, Zn(II-5-[(3,4-methylenedioxyphenyl]-10,15,20-tris-(4-carboxymethylphenylporphyrin, Cu(II-5-(4-acetoxy-3-methoxyphenyl-10,15,20-tris-(4-carboxymethylphenylporphyrin and Cu(II-5-[(3,4-methylenedioxyphenyl]-10,15,20-tris-(4-carboxymethylphenylporphyrin were synthesized using microwave-assisted synthesis. The complexes were characterized by elemental analysis, FT-IR, UV-Vis, EPR and NMR spectroscopy, which fully confirmed their structure. The spectral absorption properties of the porphyrinic complexes were studied in solvents with different polarities. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for the compounds under study, revealing high yields for the zinc derivatives. The copper complexes are not emissive and only display residual capacity for singlet oxygen formation.

Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as an Analytical Method to Investigate the Secondary Structure of a Model Protein Embedded in Solid Lipid Matrices.

Science.gov (United States)

Zeeshan, Farrukh; Tabbassum, Misbah; Jorgensen, Lene; Medlicott, Natalie J

2018-02-01

Protein drugs may encounter conformational perturbations during the formulation processing of lipid-based solid dosage forms. In aqueous protein solutions, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can investigate these conformational changes following the subtraction of spectral interference of solvent with protein amide I bands. However, in solid dosage forms, the possible spectral contribution of lipid carriers to protein amide I band may be an obstacle to determine conformational alterations. The objective of this study was to develop an ATR FT-IR spectroscopic method for the analysis of protein secondary structure embedded in solid lipid matrices. Bovine serum albumin (BSA) was chosen as a model protein, while Precirol AT05 (glycerol palmitostearate, melting point 58 ℃) was employed as the model lipid matrix. Bovine serum albumin was incorporated into lipid using physical mixing, melting and mixing, or wet granulation mixing methods. Attenuated total reflection FT-IR spectroscopy and size exclusion chromatography (SEC) were performed for the analysis of BSA secondary structure and its dissolution in aqueous media, respectively. The results showed significant interference of Precirol ATO5 with BSA amide I band which was subtracted up to 90% w/w lipid content to analyze BSA secondary structure. In addition, ATR FT-IR spectroscopy also detected thermally denatured BSA solid alone and in the presence of lipid matrix indicating its suitability for the detection of denatured protein solids in lipid matrices. Despite being in the solid state, conformational changes occurred to BSA upon incorporation into solid lipid matrices. However, the extent of these conformational alterations was found to be dependent on the mixing method employed as indicated by area overlap calculations. For instance, the melting and mixing method imparted negligible effect on BSA secondary structure, whereas the wet granulation mixing method promoted

Ames S-32 O-16 O-18 Line List for High-Resolution Experimental IR Analysis

Science.gov (United States)

Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

2016-01-01

By comparing to the most recent experimental data and spectra of the SO2 628 ?1/?3 bands (see Ulenikov et al., JQSRT 168 (2016) 29-39), this study illustrates the reliability and accuracy of the Ames-296K SO2 line list, which is accurate enough to facilitate such high-resolution spectroscopic analysis. The SO2 628 IR line list is computed on a recently improved potential energy surface (PES) refinement, denoted Ames-Pre2, and the published purely ab initio CCSD(T)/aug-cc-pVQZ dipole moment surface. Progress has been made in both energy level convergence and rovibrational quantum number assignments agreeing with laboratory analysis models. The accuracy of the computed 628 energy levels and line list is similar to what has been achieved and reported for SO2 626 and 646, i.e. 0.01-0.03 cm(exp -1) for bands up to 5500 cm(exp -1). During the comparison, we found some discrepancies in addition to overall good agreements. The three-IR-list based feature-by-feature analysis in a 0.25 cm(exp -1) spectral window clearly demonstrates the power of the current Ames line lists with new assignments, correction of some errors, and intensity contributions from varied sources including other isotopologues. We are inclined to attribute part of detected discrepancies to an incomplete experimental analysis and missing intensity in the model. With complete line position, intensity, and rovibrational quantum numbers determined at 296 K, spectroscopic analysis is significantly facilitated especially for a spectral range exhibiting such an unusually high density of lines. The computed 628 rovibrational levels and line list are accurate enough to provide alternatives for the missing bands or suspicious assignments, as well as helpful to identify these isotopologues in various celestial environments. The next step will be to revisit the SO2 828 and 646 spectral analyses.

Synthesis and spectral characterization of hydrazone derivative of furfural using experimental and DFT methods.

Science.gov (United States)

Babu, N Ramesh; Subashchandrabose, S; Ali Padusha, M Syed; Saleem, H; Erdoğdu, Y

2014-01-01

The Spectral Characterization of (E)-1-(Furan-2-yl) methylene)-2-(1-phenylvinyl) hydrazine (FMPVH) were carried out by using FT-IR, FT-Raman and UV-Vis., Spectrometry. The B3LYP/6-311++G(d,p) level of optimization has been performed on the title compound. The conformational analysis was performed for this molecule, in which the cis and trans conformers were studied for spectral characterization. The recorded spectral results were compared with calculated results. The optimized bond parameters of FMPVH molecule was compared with X-ray diffraction data of related molecule. To study the intra-molecular charge transfers within the molecule the Lewis (bonding) and Non-Lewis (anti-bonding) structural calculation was performed. The Non-linear optical behavior of the title compound was measured using first order hyperpolarizability calculation. The atomic charges were calculated and analyzed. Copyright © 2013 Elsevier B.V. All rights reserved.

Spectral Properties of Novel 1,3-oxazol-5(4H)-ones With Substituted Benzylidene and Phenyl Rings

DEFF Research Database (Denmark)

Palcut, Marián

2009-01-01

In the present work, five novel (4Z)-4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-ones (azlactones) were investigated by the infra-red (IR) and nuclear magnetic resonance spectroscopy (NMR) of the 1H and 13C nuclei. The spectral properties of the oxazolone ring were monitored with respect to the subst...

User's guide: Nimbus-7 Earth radiation budget narrow-field-of-view products. Scene radiance tape products, sorting into angular bins products, and maximum likelihood cloud estimation products

Science.gov (United States)

Kyle, H. Lee; Hucek, Richard R.; Groveman, Brian; Frey, Richard

1990-01-01

The archived Earth radiation budget (ERB) products produced from the Nimbus-7 ERB narrow field-of-view scanner are described. The principal products are broadband outgoing longwave radiation (4.5 to 50 microns), reflected solar radiation (0.2 to 4.8 microns), and the net radiation. Daily and monthly averages are presented on a fixed global equal area (500 sq km), grid for the period May 1979 to May 1980. Two independent algorithms are used to estimate the outgoing fluxes from the observed radiances. The algorithms are described and the results compared. The products are divided into three subsets: the Scene Radiance Tapes (SRT) contain the calibrated radiances; the Sorting into Angular Bins (SAB) tape contains the SAB produced shortwave, longwave, and net radiation products; and the Maximum Likelihood Cloud Estimation (MLCE) tapes contain the MLCE products. The tape formats are described in detail.

High-z X-ray Obscured Quasars in Galaxies with Extreme Mid-IR/Optical Colors

Science.gov (United States)

Piconcelli, E.; Lanzuisi, G.; Fiore, F.; Feruglio, C.; Vignali, C.; Salvato, M.; Grappioni, C.

2009-05-01

Extreme Optical/Mid-IR color cuts have been used to uncover a population of dust-enshrouded, mid-IR luminous galaxies at high redshifts. Several lines of evidence point towards the presence of an heavily absorbed, possibly Compton-thick quasar at the heart of these systems. Nonetheless, the X-ray spectral properties of these intriguing sources still remain largely unexplored. Here we present an X-ray spectroscopic study of a large sample of 44 extreme dust-obscured galaxies (EDOGs) with F24 μm/FR>2000 and F24 μm>1.3 mJy selected from a 6 deg2 region in the SWIRE fields. The application of our selection criteria to a wide area survey has been capable of unveiling a population of X-ray luminous, absorbed z>1 quasars which is mostly missed in the traditional optical/X-ray surveys performed so far. Advances in the understanding of the X-ray properties of these recently-discovered sources by Simbol-X observations will be also discussed.

UV-Vis-IR spectral complex refractive indices and optical properties of brown carbon aerosol from biomass burning

Science.gov (United States)

Sumlin, Benjamin J.; Heinson, Yuli W.; Shetty, Nishit; Pandey, Apoorva; Pattison, Robert S.; Baker, Stephen; Hao, Wei Min; Chakrabarty, Rajan K.

2018-02-01

Constraining the complex refractive indices, optical properties and size of brown carbon (BrC) aerosols is a vital endeavor for improving climate models and satellite retrieval algorithms. Smoldering wildfires are the largest source of primary BrC, and fuel parameters such as moisture content, source depth, geographic origin, and fuel packing density could influence the properties of the emitted aerosol. We measured in situ spectral (375-1047 nm) optical properties of BrC aerosols emitted from smoldering combustion of Boreal and Indonesian peatlands across a range of these fuel parameters. Inverse Lorenz-Mie algorithms used these optical measurements along with simultaneously measured particle size distributions to retrieve the aerosol complex refractive indices (m = n + iκ). Our results show that the real part n is constrained between 1.5 and 1.7 with no obvious functionality in wavelength (λ), moisture content, source depth, or geographic origin. With increasing λ from 375 to 532 nm, κ decreased from 0.014 to 0.003, with corresponding increase in single scattering albedo (SSA) from 0.93 to 0.99. The spectral variability of κ follows the Kramers-Kronig dispersion relation for a damped harmonic oscillator. For λ ≥ 532 nm, both κ and SSA showed no spectral dependency. We discuss differences between this study and previous work. The imaginary part κ was sensitive to changes in FPD, and we hypothesize mechanisms that might help explain this observation.

Mapping the spectral phase of isolated attosecond pulses by extreme-ultraviolet emission spectrum.

Science.gov (United States)

Liu, Candong; Zeng, Zhinan; Li, Ruxin; Xu, Zhizhan; Nisoli, Mauro

2015-04-20

An all-optical method is proposed for the measurement of the spectral phase of isolated attosecond pulses. The technique is based on the generation of extreme-ultraviolet (XUV) radiation in a gas by the combination of an attosecond pulse and a strong infrared (IR) pulse with controlled electric field. By using a full quantum simulation, we demonstrate that, for particular temporal delays between the two pulses, the IR field can drive back to the parent ions the photoelectrons generated by the attosecond pulse, thus leading to the generation of XUV photons. It is found that the generated XUV spectrum is notably sensitive to the chirp of the attosecond pulse, which can then be reliably retrieved. A classical quantum-path analysis is further used to quantitatively explain the main features exhibited in the XUV emission.

Inhibition of PTP1B Restores IRS1-Mediated Hepatic Insulin Signaling in IRS2-Deficient Mice

Science.gov (United States)

González-Rodríguez, Águeda; Gutierrez, Jose A. Mas; Sanz-González, Silvia; Ros, Manuel; Burks, Deborah J.; Valverde, Ángela M.

2010-01-01

OBJECTIVE Mice with complete deletion of insulin receptor substrate 2 (IRS2) develop hyperglycemia, impaired hepatic insulin signaling, and elevated gluconeogenesis, whereas mice deficient for protein tyrosine phosphatase (PTP)1B display an opposing hepatic phenotype characterized by increased sensitivity to insulin. To define the relationship between these two signaling pathways in the regulation of liver metabolism, we used genetic and pharmacological approaches to study the effects of inhibiting PTP1B on hepatic insulin signaling and expression of gluconeogenic enzymes in IRS2−/− mice. RESEARCH DESIGN AND METHODS We analyzed glucose homeostasis and insulin signaling in liver and isolated hepatocytes from IRS2−/− and IRS2−/−/PTP1B−/− mice. Additionally, hepatic insulin signaling was assessed in control and IRS2−/− mice treated with resveratrol, an antioxidant present in red wine. RESULTS In livers of hyperglycemic IRS2−/− mice, the expression levels of PTP1B and its association with the insulin receptor (IR) were increased. The absence of PTP1B in the double-mutant mice restored hepatic IRS1-mediated phosphatidylinositol (PI) 3-kinase/Akt/Foxo1 signaling. Moreover, resveratrol treatment of hyperglycemic IRS2−/− mice decreased hepatic PTP1B mRNA and inhibited PTP1B activity, thereby restoring IRS1-mediated PI 3-kinase/Akt/Foxo1 signaling and peripheral insulin sensitivity. CONCLUSIONS By regulating the phosphorylation state of IR, PTB1B determines sensitivity to insulin in liver and exerts a unique role in the interplay between IRS1 and IRS2 in the modulation of hepatic insulin action. PMID:20028942