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Sample records for absolute spectral radiance

  1. Spectral radiance source based on supercontinuum laser and wavelength tunable bandpass filter: the spectrally tunable absolute irradiance and radiance source.

    PubMed

    Levick, Andrew P; Greenwell, Claire L; Ireland, Jane; Woolliams, Emma R; Goodman, Teresa M; Bialek, Agnieszka; Fox, Nigel P

    2014-06-01

    A new spectrally tunable source for calibration of radiometric detectors in radiance, irradiance, or power mode has been developed and characterized. It is termed the spectrally tunable absolute irradiance and radiance source (STAIRS). It consists of a supercontinuum laser, wavelength tunable bandpass filter, power stabilization feedback control scheme, and output coupling optics. It has the advantages of relative portability and a collimated beam (low étendue), and is an alternative to conventional sources such as tungsten lamps, blackbodies, or tunable lasers. The supercontinuum laser is a commercial Fianium SC400-6-02, which has a wavelength range between 400 and 2500 nm and a total power of 6 W. The wavelength tunable bandpass filter, a PhotonEtc laser line tunable filter (LLTF), is tunable between 400 and 1000 nm and has a bandwidth of 1 or 2 nm depending on the wavelength selected. The collimated laser beam from the LLTF filter is converted to an appropriate spatial and angular distribution for the application considered (i.e., for radiance, irradiance, or power mode calibration of a radiometric sensor) with the output coupling optics, for example, an integrating sphere, and the spectral radiance/irradiance/power of the source is measured using a calibration optical sensor. A power stabilization feedback control scheme has been incorporated that stabilizes the source to better than 0.01% for averaging times longer than 100 s. The out-of-band transmission of the LLTF filter is estimated to be < -65 dB (0.00003%), and is sufficiently low for many end-user applications, for example the spectral radiance calibration of earth observation imaging radiometers and the stray light characterization of array spectrometers (the end-user optical sensor). We have made initial measurements of two end-user instruments with the STAIRS source, an array spectrometer and ocean color radiometer.

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

    PubMed

    Fat'yanov, O V; Asimow, P D

    2015-10-01

    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

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

    SciTech Connect

    Fat’yanov, O. V. Asimow, P. D.

    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

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

    PubMed

    Fat'yanov, O V; Asimow, P D

    2015-10-01

    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

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

    NASA Astrophysics Data System (ADS)

    Fat'yanov, O. V.; Asimow, P. D.

    2015-10-01

    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

  6. Climate Absolute Radiance and Refractivity Observatory (CLARREO)

    NASA Technical Reports Server (NTRS)

    Leckey, John P.

    2015-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a mission, led and developed by NASA, that will measure a variety of climate variables with an unprecedented accuracy to quantify and attribute climate change. CLARREO consists of three separate instruments: an infrared (IR) spectrometer, a reflected solar (RS) spectrometer, and a radio occultation (RO) instrument. The mission will contain orbiting radiometers with sufficient accuracy, including on orbit verification, to calibrate other space-based instrumentation, increasing their respective accuracy by as much as an order of magnitude. The IR spectrometer is a Fourier Transform spectrometer (FTS) working in the 5 to 50 microns wavelength region with a goal of 0.1 K (k = 3) accuracy. The FTS will achieve this accuracy using phase change cells to verify thermistor accuracy and heated halos to verify blackbody emissivity, both on orbit. The RS spectrometer will measure the reflectance of the atmosphere in the 0.32 to 2.3 microns wavelength region with an accuracy of 0.3% (k = 2). The status of the instrumentation packages and potential mission options will be presented.

  7. Spectral Dimensionality and Scale of Urban Radiance

    NASA Technical Reports Server (NTRS)

    Small, Christopher

    2001-01-01

    Characterization of urban radiance and reflectance is important for understanding the effects of solar energy flux on the urban environment as well as for satellite mapping of urban settlement patterns. Spectral mixture analyses of Landsat and Ikonos imagery suggest that the urban radiance field can very often be described with combinations of three or four spectral endmembers. Dimensionality estimates of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) radiance measurements of urban areas reveal the existence of 30 to 60 spectral dimensions. The extent to which broadband imagery collected by operational satellites can represent the higher dimensional mixing space is a function of both the spatial and spectral resolution of the sensor. AVIRIS imagery offers the spatial and spectral resolution necessary to investigate the scale dependence of the spectral dimensionality. Dimensionality estimates derived from Minimum Noise Fraction (MNF) eigenvalue distributions show a distinct scale dependence for AVIRIS radiance measurements of Milpitas, California. Apparent dimensionality diminishes from almost 40 to less than 10 spectral dimensions between scales of 8000 m and 300 m. The 10 to 30 m scale of most features in urban mosaics results in substantial spectral mixing at the 20 m scale of high altitude AVIRIS pixels. Much of the variance at pixel scales is therefore likely to result from actual differences in surface reflectance at pixel scales. Spatial smoothing and spectral subsampling of AVIRIS spectra both result in substantial loss of information and reduction of apparent dimensionality, but the primary spectral endmembers in all cases are analogous to those found in global analyses of Landsat and Ikonos imagery of other urban areas.

  8. Cloud altitude determination from infrared spectral radiances

    NASA Technical Reports Server (NTRS)

    Smith, William L.; Frey, Richard

    1990-01-01

    The CO2 slicing method is generally recognized as the most accurate means of inferring cloud altitude from passive infrared radiance observations. The method is applicable to semi-transparent and broken clouds. During the cirrus FIRE and COHMEX field experiments, CO2 channel radiance data suitable for cloud altitude specification were achieved from moderate spectral resolution satellite sounders (NOAA-TOVS and GOES-VAS) and from a High spectral resolution Interferometer Spectrometer (HIS) flown on the NASA U2/ER2 aircraft. Also aboard the ER2 was a down-looking active lidar unit capable of providing cloud top pressure verifications with high accuracy. A third instrument, the Multispectral Atmospheric Mapping Sensor (MAMS) provided 50 meter resolution infrared window data which is used wtih radiosonde data to verify the heights of middle and low level clouds. Comparisons of lidar and MAMS/radiosonde ground truth cloud heights are made with those determined from: high resolution (0.5/cm) HIS spectra, HIS spectra degraded to the moderate resolution (15/cm) of the VAS/TOVS instruments, and spectrally averaged HIS radiances for individual pairs of VAS spectral channels. The results show that the best results are achieved from high resolution spectra; the RMS difference with the ground truth is 23 mb. The RMS differences between the infrared radiance determination and ground truth increase by 35 percent when the spectral resolution is degraded to the moderate spectral resolution of the VAS/TOVS instruments and by 52 to 183 percent, depending upon channel combinations, when only two spectral channels at VAS/TOVS spectral resolution are used.

  9. Xenon arc lamp spectral radiance modelling for satellite instrument calibration

    NASA Astrophysics Data System (ADS)

    Rolt, Stephen; Clark, Paul; Schmoll, Jürgen; Shaw, Benjamin J. R.

    2016-07-01

    Precise radiometric measurements play a central role in many areas of astronomical and terrestrial observation. We focus on the use of continuum light sources in the absolute radiometric calibration of detectors in an imaging spectrometer for space applications. The application, in this instance, revolves around the ground based calibration of the Sentinel-4/UVN instrument. This imaging spectrometer instrument is expected to be deployed in 2019 and will make spatially resolved spectroscopic measurements of atmospheric chemistry. The instrument, which operates across the UV/VIS and NIR spectrum from 305-775 nm, is designed to measure the absolute spectral radiance of the Earth and compare it with the absolute spectral irradiance of the Sun. Of key importance to the fidelity of these absolute measurements is the ground based calibration campaign. Continuum lamp sources that are temporally stable and are spatially well defined are central to this process. Xenon short arc lamps provide highly intense and efficient continuum illumination in a range extending from the ultra-violet to the infra-red and their spectrum is well matched to this specific application. Despite their widespread commercial use, certain aspects of their performance are not well documented in the literature. One of the important requirements in this calibration application is the delivery of highly uniform, collimated illumination at high radiance. In this process, it cannot be assumed that the xenon arc is a point source; the spatial distribution of the radiance must be characterised accurately. We present here careful measurements that thoroughly characterise the spatial distribution of the spectral radiance of a 1000W xenon lamp. A mathematical model is presented describing the spatial distribution. Temporal stability is another exceptionally important requirement in the calibration process. As such, the paper also describes strategies to re-inforce the temporal stability of the lamp output by

  10. Issues in Absolute Spectral Radiometric Calibration: Intercomparison of Eight Sources

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Kindel, Bruce; Pilewskie, Peter

    1998-01-01

    The application of atmospheric models to AVIRIS and other spectral imaging data to derive surface reflectance requires that the sensor output be calibrated to absolute radiance. Uncertainties in absolute calibration are to be expected, and claims of 92% accuracy have been published. Measurements of accurate surface albedos and cloud absorption to be used in radiative balance calculations depend critically on knowing the absolute spectral-radiometric response of the sensor. The Earth Observing System project is implementing a rigorous program of absolute radiometric calibration for all optical sensors. Since a number of imaging instruments that provide output in terms of absolute radiance are calibrated at different sites, it is important to determine the errors that can be expected among calibration sites. Another question exists about the errors in the absolute knowledge of the exoatmospheric spectral solar irradiance.

  11. Establishing the moon as a spectral radiance standard

    USGS Publications Warehouse

    Kieffer, H.H.; Wildey, R.L.

    1996-01-01

    A new automated observatory dedicated to the radiometry of the moon has been constructed to provide new radiance information for calibration of earth-orbiting imaging instruments, particularly Earth Observing System instruments. Instrumentation includes an imaging photometer with 4.5-in. resolution on a fully digital mount and a full-aperture radiance calibration source. Interference filters within 0.35-0.95 ??m correspond to standard stellar magnitude systems, accommodate wavelengths of lunar spectral contrast, and approximate some band-passes of planned earth-orbiting instruments (ASTER, Landsat-7 ETM, MISR, MODIS, and SeaWIFS). The same equipment is used for lunar and stellar observations, with the use of an aperture stop in lunar imaging to comply with Nyquist's theorem and lengthen exposure times to avoid scintillation effects. A typical robotic night run involves observation of about 60 photometric standard stars and the moon; about 10 of the standard stars are observed repeatedly to determine atmospheric extinction, and the moon is observed several times. Observations are to be made on every photometric night during the bright half of the month for at least 4.5 years to adequately cover phase and libration variation. Each lunar image is reduced to absolute exoatmospheric radiance and reprojected to a fixed selenographic grid system. The collection of these images at various librations and phase angles will be reduced to photometric models for each of the approximately 120 000 points in the lunar grid for each filter. Radiance models of the moon can then be produced for the precise geometry of an orbiting instrument observation. Expected errors are under 1% relative and 2.5% absolute. A second telescope operating from 1.0 to 2.5 ??m is planned.

  12. On-Orbit Absolute Radiance Standard for Future IR Remote Sensing Instruments

    NASA Astrophysics Data System (ADS)

    Best, F. A.; Adler, D. P.; Pettersen, C.; Revercomb, H. E.; Gero, P. J.; Taylor, J. K.; Knuteson, R. O.; Perepezko, J. H.

    2010-12-01

    Future NASA infrared remote sensing missions, including the climate benchmark CLARREO mission will require better absolute measurement accuracy than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. As an example, instrumentation designed to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K will require high-emissivity (>0.999) calibration blackbodies with emissivity uncertainty of better than 0.06%, and absolute temperature uncertainties of better than 0.045K (3 sigma). Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and are undergoing Technology Readiness Level (TRL) advancement under the NASA Instrument Incubator Program (IIP). We present the new technologies that underlie the OARS and the results of laboratory testing that demonstrate the required accuracy is being met. The underlying technologies include on-orbit absolute temperature calibration using the transient melt signatures of small quantities (<1g) of reference materials (gallium, water, and mercury) imbedded in the blackbody cavity; and on-orbit cavity spectral emissivity measurement using a heated halo. For these emissivity measurements, a carefully baffled heated cylinder is placed in front of a blackbody in the infrared spectrometer system, and the combined radiance of the blackbody and Heated Halo reflection is observed. Knowledge of key temperatures and the viewing geometry allow the blackbody cavity spectral emissivity to be calculated. This work will culminate with an integrated subsystem that can provide on-orbit end-to-end radiometric accuracy validation for infrared remote sensing instruments.

  13. A new method for the absolute radiance calibration for UV-vis measurements of scattered sunlight

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Dörner, S.; Penning de Vries, M.; Remmers, J.; Rozanov, A.; Shaiganfar, R.

    2015-10-01

    Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds, and the shortwave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV-vis instruments that measure the spectrally resolved sky radiance, for example zenith sky differential optical absorption spectroscopy (DOAS) instruments or multi-axis (MAX)-DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method, clear-sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about < 7 %. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements be constant and known.

  14. Theory of spectral radiance of pollutants at sea

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Remote measurement of soluble pollutants that change the color of the water in the sea is reported. The sensor is a spectral radiometer that flies over the polluted area and compares its spectral radiance to that of surrounding clean seawater. A quantitative analysis of the concentration of pollutants using the measured radiance of the sea compared to laboratory measurements of reflection and transmission spectra of the pollutants is presented. The quantities involved are defined and means for measuring them are described. The equations for remote sensing with a low-flying aircraft, in which case the absorption and radiance of intervening air is negligible are derived. High-flying aircraft and satellites, in which case the radiance of intervening air is the major problem are applied.

  15. Theory of spectral radiance of pollutants at sea, volume 1

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Remote measurement of pollutants dumped in the sea, not oil slicks, but soluble pollutants that change the color of the water, is addressed. The sensor is a spectral radiometer that flies over the polluted area and compares its spectral radiance (color) to that of surrounding clean seawater. The goal is to infer the concentration of pollutants using the measured radiance of the sea compared to laboratory measurements of reflection and transmission spectra of the pollutants. The subject is treated in three steps: (1) the quantities involved are defined and means for measuring them are described; (2) the equations for remote sensing with a low-flying aircraft are derived, in which wase the absorption and radiance of intervening air is negligible; and (3) high-flying aircraft and satellites are applied, in which case the radiance of intervening air is the major problem.

  16. Calibration of the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Barnes, Robert; Baize, Rosemary; O'Connell, Joseph; Hair, Jason

    2010-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) plans to observe climate change trends over decadal time scales to determine the accuracy of climate projections. The project relies on spaceborne earth observations of SI-traceable variables sensitive to key decadal change parameters. The mission includes a reflected solar instrument retrieving at-sensor reflectance over the 320 to 2300 nm spectral range with 500-m spatial resolution and 100-km swath. Reflectance is obtained from the ratio of measurements of the earth s surface to those while viewing the sun relying on a calibration approach that retrieves reflectance with uncertainties less than 0.3%. The calibration is predicated on heritage hardware, reduction of sensor complexity, adherence to detector-based calibration standards, and an ability to simulate in the laboratory on-orbit sources in both size and brightness to provide the basis of a transfer to orbit of the laboratory calibration including a link to absolute solar irradiance measurements.

  17. Solar spectral radiance and irradiance at 225.2-319.6 nanometers

    NASA Astrophysics Data System (ADS)

    Kohl, J. L.; Parkinson, W. H.; Zapata, C. A.

    1980-11-01

    Mean absolute intensities (spectral radiance) over 0.1 nm intervals between 225.2 nm and 319.6 nm at disk center and near the limb of the sun (mu = 0.23 + or - 0.04) are derived from the high spectral resolution measurements published by Kohl, Parkinson, and Kurucz. The corresponding limb-to-center ratios and spectral irradiance values are provided. A comparison with existing measurements of solar spectral radiance and spectral irradiance for the most part shows agreement within the estimated error limits, although some narrow band variations may be outside experimental errors. The contribution to the solar constant of the 230-305 nm band is derived to be 19.7 W/square m + or - 12%.

  18. Estimates of absolute flux and radiance factor of localized regions on Mars in the 2-4 micron wavelength region

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Roush, Eileen A.; Singer, Robert B.; Lucey, Paul G.

    1992-01-01

    IRTF spectrophotometric observations of Mars obtained during the 1986 opposition are the bases for the present estimates of 2.0-4.15 micron absolute flux and radiance factor values. The bright/dark ratios obtained show a wavelength dependence similar to that observed by Bell and Crisp (1991) in 1990, but the spectral contrast for 1986 is lower than in those observations; this difference could be due to changes in the location, sample are size, and/or suspended atmospheric dust.

  19. Spectral reflectance and radiance characteristics of water pollutants

    NASA Technical Reports Server (NTRS)

    Wezernak, C. T.; Turner, R. E.; Lyzenga, D. R.

    1976-01-01

    Spectral reflectance characteristics of water pollutants and water bodies were compiled using the existing literature. Radiance calculations were performed at satellite altitude for selected illumination angles and atmospheric conditions. The work described in this report was limited to the reflective portion of the spectrum between 0.40 micrometer to 1.0 micrometer.

  20. Radiance factor calibration of near-infrared spectral images of Mars

    NASA Astrophysics Data System (ADS)

    Klassen, David R.; Bell, James F.

    2003-05-01

    We present radiometrically calibrated spectrophotometric images of Mars taken at the NASA Infrared Telescope Facility (IRTF) near and during the 1995 and 1999 oppositions. Absolute intensity and radiance factor ( r F = I/F) values have been calculated for approximately 95% of the surface over all longitudes between -70° to 90° latitude in the 1.5- to 4.1-μm spectral region at a spectral resolution (Δλ/λ) of 1.5%. Values of radiance factor range from r F = 0.4 to 0.6 at 2.2 μm for the bright regions such as Moab and Arabia to r F = 0.12 to 0.3 at 2.2 μm around the dark regions Syrtis Major and Acidalia Planitia. Variations are seen due to seasonal dust and/or condensate cloud cover and viewing geometry. Our results are generally consistent with the few reported previous radiance factor determinations for Mars. These data are unique among ground-based data in their relatively high spatial resolution (≲200 km/pixel at the sub-Earth point) and coverage combined with their spectral resolution and coverage. These radiometrically calibrated observations can be used as input to studies focusing on spectral unmixing of surface and atmospheric components, radiative transfer modeling of disk and limb radiances, and photometric modeling of the martian phase function.

  1. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  2. Quantitative Spectral Radiance Measurements in the HYMETS Arc Jet

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Hires, Drew V.; Johansen, Craig T.; Bathel, Brett F.; Jones, Stephen B.; Gragg, Jeffrey G.; Splinter, Scott C.

    2012-01-01

    Calibrated spectral radiance measurements of gaseous emission spectra have been obtained from the HYMETS (Hypersonic Materials Environmental Test System) 400 kW arc-heated wind tunnel at NASA Langley Research Center. A fiber-optic coupled spectrometer collected natural luminosity from the flow. Spectral radiance measurements are reported between 340 and 1000 nm. Both Silicon Carbide (SiC) and Phenolic Impregnated Carbon Ablator (PICA) samples were placed in the flow. Test gases studied included a mostly-N2 atmosphere (95% nitrogen, 5% argon), a simulated Earth Air atmosphere (75% nitrogen, 20% oxygen, 5% argon) and a simulated Martian atmosphere (71% carbon dioxide, 24% nitrogen, 5% argon). The bulk enthalpy of the flow was varied as was the location of the measurement. For the intermediate flow enthalpy tested (20 MJ/kg), emission from the Mars simulant gas was about 10 times higher than the Air flow and 15 times higher than the mostly-N2 atmosphere. Shock standoff distances were estimated from the spectral radiance measurements. Within-run, run-to-run and day-to-day repeatability of the emission were studied, with significant variations (15-100%) noted.

  3. Preliminary Error Budget for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Gubbels, Timothy; Barnes, Robert

    2011-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) plans to observe climate change trends over decadal time scales to determine the accuracy of climate projections. The project relies on spaceborne earth observations of SI-traceable variables sensitive to key decadal change parameters. The mission includes a reflected solar instrument retrieving at-sensor reflectance over the 320 to 2300 nm spectral range with 500-m spatial resolution and 100-km swath. Reflectance is obtained from the ratio of measurements of the earth s surface to those while viewing the sun relying on a calibration approach that retrieves reflectance with uncertainties less than 0.3%. The calibration is predicated on heritage hardware, reduction of sensor complexity, adherence to detector-based calibration standards, and an ability to simulate in the laboratory on-orbit sources in both size and brightness to provide the basis of a transfer to orbit of the laboratory calibration including a link to absolute solar irradiance measurements. The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe high-accuracy, long-term climate change trends and to use decadal change observations as the most critical method to determine the accuracy of climate change projections such as those in the IPCC Report. A rigorously known accuracy of both decadal change observations as well as climate projections is critical in order to enable sound policy decisions. The CLARREO Project will implement a spaceborne earth observation mission designed to provide rigorous SI traceable observations (i.e., radiance, reflectance, and refractivity) that are sensitive to a wide range of key decadal change variables, including: 1) Surface temperature and atmospheric temperature profile 2) Atmospheric water vapor profile 3) Far infrared water vapor greenhouse 4) Aerosol properties and anthropogenic aerosol direct radiative forcing 5) Total and spectral solar

  4. A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Dörner, S.; Penning de Vries, M.; Remmers, J.; Rozanov, A.; Shaiganfar, R.

    2015-05-01

    Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS-) instruments or Multi-AXis (MAX-) DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

  5. The University of Wisconsin Space Science and Engineering Center Absolute Radiance Interferometer (ARI): instrument overview and radiometric performance

    NASA Astrophysics Data System (ADS)

    Taylor, Joseph K.; Revercomb, Henry E.; Best, Fred A.; Gero, P. Jonathan; Genest, Jerome; Buijs, Henry; Grandmont, Frederic J.; Tobin, David C.; Knuteson, Robert O.

    2014-11-01

    Spectrally resolved infrared (IR) and far infrared (FIR) radiances measured from orbit with extremely high absolute accuracy are a critical observation for future climate benchmark missions. For the infrared radiance spectra, it has been determined that a measurement accuracy, expressed as an equivalent brightness temperature error, of 0.1 K (k = 3) confirmed on orbit is required for signal detection above natural variability for decadal climate signatures [1, 2]. The challenge in the sensor development for a climate benchmark measurement mission is to achieve ultra-high accuracy with a design that can be flight qualified, has long design life, and is reasonably small, simple, and affordable. The required simplicity is achievable due to the large differences in the sampling and noise requirements for the benchmark climate measurement from those of the typical remote sensing infrared sounders for weather research or operational weather prediction. The University of Wisconsin Space Science and Engineering Center, with funding from the NASA Instrument Incubator Program (IIP), developed the Absolute Radiance Interferometer (ARI), which is designed to meet the uncertainty requirements needed to establish spectrally resolved thermal infrared climate benchmark measurements from space. The ARI is a prototype instrument designed to have a short upgrade path to a spaceflight instrument. Recent vacuum testing of the ARI, conducted under funding from the NASA Earth Science Technology Office, has demonstrated the capability to meet the 0.1 K (k = 3) uncertainty requirement on-orbit. An overview of the instrument design and summary of the radiometric performance verification of the UW-SSEC ARI will be presented.

  6. Infrared Spectral Radiance Intercomparisons With Satellite and Aircraft Sensors

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Zhou, Daniel K.; Liu, Xu; Smith, William L.

    2014-01-01

    Measurement system validation is critical for advanced satellite sounders to reach their full potential of improving observations of the Earth's atmosphere, clouds, and surface for enabling enhancements in weather prediction, climate monitoring capability, and environmental change detection. Experimental field campaigns, focusing on satellite under-flights with well-calibrated FTS sensors aboard high-altitude aircraft, are an essential part of the validation task. Airborne FTS systems can enable an independent, SI-traceable measurement system validation by directly measuring the same level-1 parameters spatially and temporally coincident with the satellite sensor of interest. Continuation of aircraft under-flights for multiple satellites during multiple field campaigns enables long-term monitoring of system performance and inter-satellite cross-validation. The NASA / NPOESS Airborne Sounder Testbed - Interferometer (NAST-I) has been a significant contributor in this area by providing coincident high spectral/spatial resolution observations of infrared spectral radiances along with independently-retrieved geophysical products for comparison with like products from satellite sensors being validated. This presentation gives an overview of benefits achieved using airborne sensors such as NAST-I utilizing examples from recent field campaigns. The methodology implemented is not only beneficial to new sensors such as the Cross-track Infrared Sounder (CrIS) flying aboard the Suomi NPP and future JPSS satellites but also of significant benefit to sensors of longer flight heritage such as the Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI) on the AQUA and METOP-A platforms, respectively, to ensure data quality continuity important for climate and other applications. Infrared spectral radiance inter-comparisons are discussed with a particular focus on usage of NAST-I data for enabling inter-platform cross-validation.

  7. Instrumentation and First Results of the Reflected Solar Demonstration System for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Thome, Kurtis; Hair, Jason; McAndrew, Brendan; Jennings, Don; Rabin, Douglas; Daw, Adrian; Lundsford, Allen

    2012-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission key goals include enabling observation of high accuracy long-term climate change trends, use of these observations to test and improve climate forecasts, and calibration of operational and research sensors. The spaceborne instrument suites include a reflected solar spectroradiometer, emitted infrared spectroradiometer, and radio occultation receivers. The requirement for the RS instrument is that derived reflectance must be traceable to Sl standards with an absolute uncertainty of <0.3% and the error budget that achieves this requirement is described in previo1L5 work. This work describes the Solar/Lunar Absolute Reflectance Imaging Spectroradiometer (SOLARIS), a calibration demonstration system for RS instrument, and presents initial calibration and characterization methods and results. SOLARIS is an Offner spectrometer with two separate focal planes each with its own entrance aperture and grating covering spectral ranges of 320-640, 600-2300 nm over a full field-of-view of 10 degrees with 0.27 milliradian sampling. Results from laboratory measurements including use of integrating spheres, transfer radiometers and spectral standards combined with field-based solar and lunar acquisitions are presented. These results will be used to assess the accuracy and repeatability of the radiometric and spectral characteristics of SOLARIS, which will be presented against the sensor-level requirements addressed in the CLARREO RS instrument error budget.

  8. Geophysical Information from Advanced Sounder Infrared Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Zhou, Daniel K.; Liu, Xu; Smith, William L.

    2012-01-01

    Advanced satellite sensors are tasked with improving global observations of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Satisfying this type of improvement for inferred geophysical information from these observations requires optimal usage of data from current systems as well as enhancements to future sensors. This presentation addresses the information content present in infrared spectral radiance from advanced atmospheric sounders with an emphasis on knowledge of thermodynamic state and trace species. Results of trade-off studies conducted to evaluate the impact of spectral resolution, spectral coverage, instrument noise, and a priori knowledge on remote sensing system information content will be discussed. A focus is placed on information achievable from the Atmospheric InfraRed Sounder (AIRS) on the NASA EOS Aqua satellite in orbit since 2002, the Infrared Atmospheric Sounding Interferometer (IASI) aboard MetOp-A since 2006, and the Cross-track Infrared Sounder (CrIS) instrument aboard the NPP and JPSS series of satellites which began 28 October 2011.

  9. Comparison of spectral radiance responsivity calibration techniques used for backscatter ultraviolet satellite instruments

    NASA Astrophysics Data System (ADS)

    Kowalewski, M. G.; Janz, S. J.

    2015-02-01

    Methods of absolute radiometric calibration of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration uncertainties. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV, Total Ozone Mapping Spectrometer, Ozone Mapping Instrument, and Global Ozone Monitoring Experiment 2 using standardized procedures traceable to national standards. These sphere-based spectral responsivities agree to within the derived combined standard uncertainty of 1.87% relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary spectral radiance responsivity calibration method for BUV instruments. The combined standard uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Center’s Radiometric Calibration and Development Laboratory is shown to less than 2% at 250 nm when using a single traceable calibration standard.

  10. Estimation of spectral distribution of sky radiance using a commercial digital camera.

    PubMed

    Saito, Masanori; Iwabuchi, Hironobu; Murata, Isao

    2016-01-10

    Methods for estimating spectral distribution of sky radiance from images captured by a digital camera and for accurately estimating spectral responses of the camera are proposed. Spectral distribution of sky radiance is represented as a polynomial of the wavelength, with coefficients obtained from digital RGB counts by linear transformation. The spectral distribution of radiance as measured is consistent with that obtained by spectrometer and radiative transfer simulation for wavelengths of 430-680 nm, with standard deviation below 1%. Preliminary applications suggest this method is useful for detecting clouds and studying the relation between irradiance at the ground and cloud distribution.

  11. Estimation of spectral distribution of sky radiance using a commercial digital camera.

    PubMed

    Saito, Masanori; Iwabuchi, Hironobu; Murata, Isao

    2016-01-10

    Methods for estimating spectral distribution of sky radiance from images captured by a digital camera and for accurately estimating spectral responses of the camera are proposed. Spectral distribution of sky radiance is represented as a polynomial of the wavelength, with coefficients obtained from digital RGB counts by linear transformation. The spectral distribution of radiance as measured is consistent with that obtained by spectrometer and radiative transfer simulation for wavelengths of 430-680 nm, with standard deviation below 1%. Preliminary applications suggest this method is useful for detecting clouds and studying the relation between irradiance at the ground and cloud distribution. PMID:26835780

  12. Results from recent vacuum testing of an on-orbit absolute radiance standard (OARS) intended for the next generation of infrared remote sensing instruments

    NASA Astrophysics Data System (ADS)

    Best, Fred A.; Adler, Douglas P.; Pettersen, Claire; Revercomb, Henry E.; Gero, P. Jonathan; Taylor, Joseph K.; Knuteson, Robert O.

    2014-11-01

    Future NASA infrared remote sensing missions will require better absolute measurement accuracies than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. To establish a CLARRREO-type climate benchmark, instrumentation will need to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K, verified onorbit. This will require an independent high-emissivity (<0.999) verification blackbody with an emissivity uncertainty of better than 0.06%, an absolute temperature uncertainty of better than 0.045K (3 sigma), and the capability of operation over a wide range of (Earth scene) temperatures. Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and have undergone further refinement under funding from NASA's Earth Science and Technology Office, culminating in an end-to-end demonstration under vacuum with a prototype climate benchmark instrument. We present the new technologies that underlie the OARS, and the results of testing that demonstrate the required accuracy is being met in a vacuum environment. The underlying technologies include: on-orbit absolute temperature calibration using the transient melt signatures of small quantities (<1g) of reference materials (gallium, water, and mercury) imbedded in the blackbody cavity; and on-orbit cavity spectral emissivity measurement using a carefully baffled heated halo placed in front of the OARS blackbody viewed by the infrared spectrometer system. Emissivity is calculated from the radiance measured from the blackbody combined with the knowledge of key temperatures and radiometric view factors.

  13. A New Measurement of the Absolute Spectral Reflectance of the Moon

    NASA Technical Reports Server (NTRS)

    Lawrence, S. J.; Lau, E.; Steutel, D.; Stopar, J. D.; Wilcox, B. B.; Lucey, P. G.

    2003-01-01

    The spectral reflectance of the Moon is an important property for studies of lunar geology, quantitative physical modeling of the moon, and in-flight calibration of spacecraft sensors. Previous studies have claimed that telescopic absolute reflectance values for the Moon are greater than laboratory reflectance measurements by a factor of two. In order to confirm these results, we performed ground-based observations of the lunar surface using a visible/near-infrared spectroradiometer and compared the measured lunar surface radiance to solar radiance corrected for atmospheric scattering and absorption. These data were compared to previously obtained laboratory reflectance measurements from Apollo soil samples.

  14. Demonstrating the Error Budget for the Climate Absolute Radiance and Refractivity Observatory Through Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2016-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

  15. Demonstrating the error budget for the Climate Absolute Radiance and Refractivity Observatory through solar irradiance measurements

    NASA Astrophysics Data System (ADS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2015-09-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a testbed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

  16. Reflectance- and radiance-based methods for the in-flight absolute calibration of multispectral sensors

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

    1987-01-01

    Variations reported in the in-flight absolute radiometric calibration of the Coastal Zone Color Scanner (CZCS) and the Thematic Mapper (TM) on Landsat 4 are reviewed. At short wavelengths these sensors exhibited a gradual reduction in response, while in the midinfrared the TM showed oscillatory variations, according to the results of TM internal calibration. The methodology and results are presented for five reflectance-based calibrations of the Landsat 5 TM at White Sands, NM, in the period July 1984 to November 1985. These show a + or - 2.8 percent standard deviation for the six solar-reflective bands. Analysis and preliminary results of a second, independent calibration method, based on radiance measurements from a helicopter at White Sands, indicate that this is potentially an accurate method for corroborating the results from the reflectance-based method.

  17. Reflectance- and radiance-based methods for the in-flight absolute calibration of multispectral sensors

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

    1987-06-01

    Variations reported in the in-flight absolute radiometric calibration of the Coastal Zone Color Scanner (CZCS) and the Thematic Mapper (TM) on Landsat 4 are reviewed. At short wavelengths these sensors exhibited a gradual reduction in response, while in the midinfrared the TM showed oscillatory variations, according to the results of TM internal calibration. The methodology and results are presented for five reflectance-based calibrations of the Landsat 5 TM at White Sands, NM, in the period July 1984 to November 1985. These show a + or - 2.8 percent standard deviation for the six solar-reflective bands. Analysis and preliminary results of a second, independent calibration method, based on radiance measurements from a helicopter at White Sands, indicate that this is potentially an accurate method for corroborating the results from the reflectance-based method.

  18. Facility for spectral irradiance and radiance responsivity calibrations using uniform sources

    SciTech Connect

    Brown, Steven W.; Eppeldauer, George P.; Lykke, Keith R

    2006-11-10

    Detectors have historically been calibrated for spectral power responsivity at the National Institute of Standards and Technology by using a lamp-monochromator system to tune the wavelength of the excitation source. Silicon detectors can be calibrated in the visible spectral region with combined standard uncertainties at the 0.1% level. However,uncertainties increase dramatically when measuring an instrument's spectral irradiance or radiance responsivity. We describe what we believe to be a new laser-based facility for spectral irradiance and radiance responsivity calibrations using uniform sources (SIRCUS) that was developed to calibrate instruments directly in irradiance or radiance mode with uncertainties approaching or exceeding those available for spectral power responsivity calibrations. In SIRCUS, the emission from high-power, tunable lasers is introduced into an integrating sphere using optical fibers, producing uniform, quasi-Lambertian, high-radiant-flux sources. Reference standard irradiance detectors, calibrated directly against national primary standards for spectral power responsivity and aperture area measurement,are used to determine the irradiance at a reference plane. Knowing the measurement geometry, the source radiance can be readily determined as well. The radiometric properties of the SIRCUS source coupled with state-of-the-art transfer standard radiometers whose responsivities are directly traceable to primary national radiometric scales result in typical combined standard uncertainties in irradiance and radiance responsivity calibrations of less than 0.1%. The details of the facility and its effect on primary national radiometric scales are discussed.

  19. A solely radiance-based spectral anisotropic distribution model and its application in deriving clear-sky spectral fluxes

    NASA Astrophysics Data System (ADS)

    Song, L.; Huang, X.

    2011-12-01

    Anisotropic distribution model (ADM) plays a uniquely central role in converting broadband radiance measurement to broadband flux. Scene type classifications are usually needed for such ADM and such classifications are usually done with auxiliary measurements and information since broadband radiance does not contain detailed information about temperature, humidity, and clouds. Recently Huang et al. (2008 and 2010) has developed spectral ADM based on such scene type classifications and successfully derived spectral flux from spectral radiance measurement. Unlike broadband radiances, the spectrally resolved radiances indeed contain rich information about temperature, humidity, and clouds. Therefore, it is meaningful to explore whether it is possible to develop scene-type classification solely based on spectral radiance and consequently to construct spectral ADM solely base on radiances measurement. Using AIRS spectrum as an example, here we develop a clear-sky scene classification algorithm solely based on AIRS radiances. The definitions of scene types are similar to those of clear-sky scene types used in CERES SSF algorithm, which are discrete intervals based on surface skin temperature, lapse rate (temperature change of the first 300 mb above the surface), and the total precipitable water (TPW). Brightness temperature of AIRS channel at 963.8 cm-1 are used for determine corresponding discrete intervals of surface skin temperature. This channel is also used in conjunction with a channel at 748.6 cm-1 for categorizing the lapse rate. Given the slow varying of water vapor continuum in the window region and the dominant weight of lower tropospheric humidity in TPW, a double-differential technique is used to categorize the TPW. By choosing two pairs of AIRS channels with similar frequency intervals, the technique can classify the TPW without any a priori information about continuum absorption since double differencing largely remove the slow-varying continuum

  20. Spectral radiance calibrations between 165-300 nm - An interlaboratory comparison

    NASA Technical Reports Server (NTRS)

    Bridges, J. M.; Ott, W. R.; Pitz, E.; Schulz, A.; Einfeld, D.; Stuck, D.

    1977-01-01

    The spectral radiance of deuterium lamps calibrated by the Max-Planck-Institut fuer Astronomie (MPI), by the U.S. National Bureau of Standards (NBS), and by the Physikalisch-Technische Bundesanstalt (PTB) are compared to check the agreement of UV radiometric scales. The NBS group used the optically thin continuum radiation from a wall-stabilized hydrogen arc as its fundamental radiometric standard, while the MPI and PTB groups used the synchrotron radiation facility in DESY. It is found that the spectral radiance scales based upon the DESY synchrotron and the NBS hydrogen arc are consistent, at least for one wavelength relative to another.

  1. Rayleigh radiance computations for satellite remote sensing: accounting for the effect of sensor spectral response function.

    PubMed

    Wang, Menghua

    2016-05-30

    To understand and assess the effect of the sensor spectral response function (SRF) on the accuracy of the top of the atmosphere (TOA) Rayleigh-scattering radiance computation, new TOA Rayleigh radiance lookup tables (LUTs) over global oceans and inland waters have been generated. The new Rayleigh LUTs include spectral coverage of 335-2555 nm, all possible solar-sensor geometries, and surface wind speeds of 0-30 m/s. Using the new Rayleigh LUTs, the sensor SRF effect on the accuracy of the TOA Rayleigh radiance computation has been evaluated for spectral bands of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP) satellite and the Joint Polar Satellite System (JPSS)-1, showing some important uncertainties for VIIRS-SNPP particularly for large solar- and/or sensor-zenith angles as well as for large Rayleigh optical thicknesses (i.e., short wavelengths) and bands with broad spectral bandwidths. To accurately account for the sensor SRF effect, a new correction algorithm has been developed for VIIRS spectral bands, which improves the TOA Rayleigh radiance accuracy to ~0.01% even for the large solar-zenith angles of 70°-80°, compared with the error of ~0.7% without applying the correction for the VIIRS-SNPP 410 nm band. The same methodology that accounts for the sensor SRF effect on the Rayleigh radiance computation can be used for other satellite sensors. In addition, with the new Rayleigh LUTs, the effect of surface atmospheric pressure variation on the TOA Rayleigh radiance computation can be calculated precisely, and no specific atmospheric pressure correction algorithm is needed. There are some other important applications and advantages to using the new Rayleigh LUTs for satellite remote sensing, including an efficient and accurate TOA Rayleigh radiance computation for hyperspectral satellite remote sensing, detector-based TOA Rayleigh radiance computation, Rayleigh radiance calculations for high altitude

  2. Rayleigh radiance computations for satellite remote sensing: accounting for the effect of sensor spectral response function.

    PubMed

    Wang, Menghua

    2016-05-30

    To understand and assess the effect of the sensor spectral response function (SRF) on the accuracy of the top of the atmosphere (TOA) Rayleigh-scattering radiance computation, new TOA Rayleigh radiance lookup tables (LUTs) over global oceans and inland waters have been generated. The new Rayleigh LUTs include spectral coverage of 335-2555 nm, all possible solar-sensor geometries, and surface wind speeds of 0-30 m/s. Using the new Rayleigh LUTs, the sensor SRF effect on the accuracy of the TOA Rayleigh radiance computation has been evaluated for spectral bands of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP) satellite and the Joint Polar Satellite System (JPSS)-1, showing some important uncertainties for VIIRS-SNPP particularly for large solar- and/or sensor-zenith angles as well as for large Rayleigh optical thicknesses (i.e., short wavelengths) and bands with broad spectral bandwidths. To accurately account for the sensor SRF effect, a new correction algorithm has been developed for VIIRS spectral bands, which improves the TOA Rayleigh radiance accuracy to ~0.01% even for the large solar-zenith angles of 70°-80°, compared with the error of ~0.7% without applying the correction for the VIIRS-SNPP 410 nm band. The same methodology that accounts for the sensor SRF effect on the Rayleigh radiance computation can be used for other satellite sensors. In addition, with the new Rayleigh LUTs, the effect of surface atmospheric pressure variation on the TOA Rayleigh radiance computation can be calculated precisely, and no specific atmospheric pressure correction algorithm is needed. There are some other important applications and advantages to using the new Rayleigh LUTs for satellite remote sensing, including an efficient and accurate TOA Rayleigh radiance computation for hyperspectral satellite remote sensing, detector-based TOA Rayleigh radiance computation, Rayleigh radiance calculations for high altitude

  3. Initial analyses of surface spectral radiance between observations and Line-By-Line calculations

    SciTech Connect

    Brown, P.D.; Clough, S.A.; Miller, N.E.; Shippert, T.R.; Turner, D.D.

    1996-04-01

    The evaluation an improvement of radiative transfer calculations are essential to attain improved performance of general circulation models (GCMs) for climate change applications. A Quality Measurement Experiment (QME) is being conducted to analyze the spectral residuals between the downwelling longwave radiance measured by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) and spectral radiance calculated by the Line-By-Line Radiative Transfer Model (LBLRTM). The three critical components of this study are (1) the assessment of the quality of the high resolution AERI measurements, (2) the assessment of the ability to define the atmospheric state in the radiating column, and (3) the evaluation of the capability of LBLRTM. Validations have been performed on spectral radiance data, obtained from April 1994 through July 1994, through the analysis of the spectral interval and physical process. The results are archived as a function of time, enabling the retrieval of specific data and facilitating investigations and diurnal effects, seasonal effects, and longer-term trends. While the initial focus is restricted to clear-sky analyses, efforts are under way to include the effects of clouds and aerosols. Plans are well formulated for the extension of the current approach to the shortwave. An overview of the concept of the QME is described by Miller et al. (1994), and a detailed description of this study is provided by Clough et al. (1994).

  4. Spectral radiance measurements and calculated soot concentrations along the length of an experimental combustor

    NASA Technical Reports Server (NTRS)

    Norgren, C. T.; Ingebo, R. D.

    1976-01-01

    Radiometric data were obtained over a range of parametric test conditions at three positions along the length of an experimental combustor segment corresponding to the primary, intermediate, and dilution zones. The concentration of soot entrained in the combustion gases was calculated by a technique using spectral radiance measurements. Tests were conducted primarily with Jet A fuel, although limited data were taken with two fuels having higher aromatic content, diesel oil number 2 and a blend of 40 percent tetralin in Jet A fuel. Radiometric observation of the combustion gases indicated that the maximum total radiance peaked at the intermediate zone, which was located immediately upstream of the dilution holes. Soot concentrations calculated from optical measurements in the dilution zone compared favorably with those obtained by in situ gas sampling at the exhaust. The total radiance increased with the higher aromatic content fuels.

  5. Lunar Spectral Irradiance and Radiance (LUSI): New Instrumentation to Characterize the Moon as a Space-Based Radiometric Standard.

    PubMed

    Smith, Allan W; Lorentz, Steven R; Stone, Thomas C; Datla, Raju V

    2012-01-01

    The need to understand and monitor climate change has led to proposed radiometric accuracy requirements for space-based remote sensing instruments that are very stringent and currently outside the capabilities of many Earth orbiting instruments. A major problem is quantifying changes in sensor performance that occur from launch and during the mission. To address this problem on-orbit calibrators and monitors have been developed, but they too can suffer changes from launch and the harsh space environment. One solution is to use the Moon as a calibration reference source. Already the Moon has been used to remove post-launch drift and to cross-calibrate different instruments, but further work is needed to develop a new model with low absolute uncertainties capable of climate-quality absolute calibration of Earth observing instruments on orbit. To this end, we are proposing an Earth-based instrument suite to measure the absolute lunar spectral irradiance to an uncertainty(1) of 0.5 % (k=1) over the spectral range from 320 nm to 2500 nm with a spectral resolution of approximately 0.3 %. Absolute measurements of lunar radiance will also be acquired to facilitate calibration of high spatial resolution sensors. The instruments will be deployed at high elevation astronomical observatories and flown on high-altitude balloons in order to mitigate the effects of the Earth's atmosphere on the lunar observations. Periodic calibrations using instrumentation and techniques available from NIST will ensure traceability to the International System of Units (SI) and low absolute radiometric uncertainties.

  6. Lunar Spectral Irradiance and Radiance (LUSI): New Instrumentation to Characterize the Moon as a Space-Based Radiometric Standard

    PubMed Central

    Smith, Allan W.; Lorentz, Steven R.; Stone, Thomas C.; Datla, Raju V.

    2012-01-01

    The need to understand and monitor climate change has led to proposed radiometric accuracy requirements for space-based remote sensing instruments that are very stringent and currently outside the capabilities of many Earth orbiting instruments. A major problem is quantifying changes in sensor performance that occur from launch and during the mission. To address this problem on-orbit calibrators and monitors have been developed, but they too can suffer changes from launch and the harsh space environment. One solution is to use the Moon as a calibration reference source. Already the Moon has been used to remove post-launch drift and to cross-calibrate different instruments, but further work is needed to develop a new model with low absolute uncertainties capable of climate-quality absolute calibration of Earth observing instruments on orbit. To this end, we are proposing an Earth-based instrument suite to measure the absolute lunar spectral irradiance to an uncertainty1 of 0.5 % (k=1) over the spectral range from 320 nm to 2500 nm with a spectral resolution of approximately 0.3 %. Absolute measurements of lunar radiance will also be acquired to facilitate calibration of high spatial resolution sensors. The instruments will be deployed at high elevation astronomical observatories and flown on high-altitude balloons in order to mitigate the effects of the Earth’s atmosphere on the lunar observations. Periodic calibrations using instrumentation and techniques available from NIST will ensure traceability to the International System of Units (SI) and low absolute radiometric uncertainties. PMID:26900523

  7. A rapid retrieval methodology based on the spectrally integrated Voigt function for space observation spectral radiance data

    NASA Astrophysics Data System (ADS)

    Quine, Brendan M.; Abrarov, Sanjar M.; Jagpal, Raj K.

    2014-06-01

    In our recent publication, we proposed the application of the spectrally integrated Voigt function (SIVF) to a line-by-line (LBL) radiative transfer modelling1. We applied the GENSPECT LBL radiative transfer model that utilizes the HITRAN database to generate synthetic spectral data due to thermal or solar radiation of the Earth or planetary atmosphere2. It has been shown that the SIVF methodology enables the computation of a LBL radiative transfer at reduced spectral resolution model without loss in accuracy. In contrast to the traditional method of computation, the SIVF implementation accounts for the area under the Voigt function between adjacent grid points resulting in well-preserved shape of a spectral radiance even at low spectral resolution. This significant advantage of the SIVF methodology can be applied in the rapid retrieval of the space observation data, required for real-time control and decision making in future generation of the Argus3 remote-sensing microspectrometers. The spectrally integrated methodology can be generalized to other linebroadening profiles, such as Galatry, Rautian-Sobelman or speed dependent profiles, to prevent underestimation of the spectral radiance that always occurs at reduced spectral resolution1 in any LBL radiative transfer model using a traditional method of computation.

  8. Nimbus 7 Solar Backscatter Ultraviolet (SBUV) spectral scan solar irradiance and Earth radiance product user's guide

    NASA Technical Reports Server (NTRS)

    Schlesinger, Barry M.; Cebula, Richard P.; Heath, Donald F.; Fleig, Albert J.

    1988-01-01

    The archived tape products from the spectral scan mode measurements of solar irradiance (SUNC tapes) and Earth radiance (EARTH tapes) by the Solar Backscatter UV (SBUV) instrument aboard Nimbus 7 are described. Incoming radiation from 160 to 400 nm is measured at intervals of 0.2 nm. The scan-to-scan repeatability of the solar irradiance measurements ranges from approximately 0.5 to 1 percent longward of 280 nm, to 2 percent around 210 nm and 4 percent near 175 nm. The repeatability of the Earth radiance values ranges from 2 to 3 percent at longer wavelengths and low zenith angles to 10 percent at shorter wavelengths and high zenith angles. The tape formats are described in detail, including file structure and contents of each type of record. Catalogs of the tapes and the time period covered are provided, along with lists of the days lacking solar irradiance measurements and the days dedicated to Earth radiance measurements. The method for production of the tapes is outlined and quality control measures are described. How radiances and irradiances are derived from the raw counts, the corrections for changes in instrument sensitivity, and related uncertainties are discussed.

  9. [Study on the absolute spectral irradiation calibration method for far ultraviolet spectrometer in remote sensing].

    PubMed

    Yu, Lei; Lin, Guan-Yu; Chen, Bin

    2013-01-01

    The present paper studied spectral irradiation responsivities calibration method which can be applied to the far ultraviolet spectrometer for upper atmosphere remote sensing. It is difficult to realize the calibration for far ultraviolet spectrometer for many reasons. Standard instruments for far ultraviolet waveband calibration are few, the degree of the vacuum experiment system is required to be high, the stabilities of the experiment are hardly maintained, and the limitation of the far ultraviolet waveband makes traditional diffuser and the integrating sphere radiance calibration method difficult to be used. To solve these problems, a new absolute spectral irradiance calibration method was studied, which can be applied to the far ultraviolet calibration. We build a corresponding special vacuum experiment system to verify the calibration method. The light source system consists of a calibrated deuterium lamp, a vacuum ultraviolet monochromater and a collimating system. We used the calibrated detector to obtain the irradiance responsivities of it. The three instruments compose the calibration irradiance source. We used the "calibration irradiance source" to illuminate the spectrometer prototype and obtained the spectral irradiance responsivities. It realized the absolute spectral irradiance calibration for the far ultraviolet spectrometer utilizing the calibrated detector. The absolute uncertainty of the calibration is 7.7%. The method is significant for the ground irradiation calibration of the far ultraviolet spectrometer in upper atmosphere remote sensing.

  10. Final Report: High Spectral Resolution Atmospheric Emitted Radiance Studies with the ARM UAV

    SciTech Connect

    Revercomb, Henry E.

    1999-12-31

    The active participation in the Atmospheric Radiation Measurement (ARM) Unmanned Airborne Vehicle (UAV) science team that was anticipated in the grant proposal was indefinitely delayed after the first year due to a programmatic decision to exclude the high spectral resolution observations from the existing ARM UAV program. However, this report shows that substantial progress toward the science objectives of this grant have made with the help of separate funding from NASA and other agencies. In the four year grant period (including time extensions), a new high spectral resolution instrument has been flown and has successfully demonstrated the ability to obtain measurements of the type needed in the conduct of this grant. In the near term, the third water vapor intensive observing period (WVIOP-3) in October 2000 will provide an opportunity to bring the high spectral resolution observations of upwelling radiance into the ARM program to complement the downwelling radiance observations from the existing ARM AERI instruments. We look forward to a time when the ARM-UAV program is able to extend its scope to include the capability for making these high spectral resolution measurements from a UAV platform.

  11. Cloud discrimination and spectral radiance estimation from a digital sky images

    NASA Astrophysics Data System (ADS)

    Saito, M.; Iwabuchi, H.; Murata, I.

    2015-12-01

    Clouds cover more than 60% of the globe with high impacts on incoming solar irradiance on the ground as well as the radiative energy transfer in the Earth-atmosphere system. Several method for detecting clouds from sky images have been developed, and digital signals available from the JPEG image have nonlinear relationship with the corresponding spectral radiances, which may lead to cloud misclassifications. In this work, a method for cloud discrimination from sky images in RAW format taken from a commercial digital camera is developed. The method uses the clear sky index (CSI). In order to take into account the spectral response in red-green-blue (RGB) channels of the camera as well as lens characteristics, these characteristics are first inferred very accurately with a laboratory experiment. Spectral radiance is represented in a simple form with spectra of incoming solar radiation at the top of atmosphere and ozone transmittance and a polynominal with three coefficients that include the intensity index, the molecular index (MI) and the small particle index (SPI). These coefficients can be obtained from the digital RGB RAW counts by linear transformation. The MI and the SPI can be converted to the CSI, which takes different value from that at clear sky and cloudy pixels. Simultaneous observations with the lidar and the digital camera at Tohoku University show that the CSI can discriminate cloud and clear sky at every pixel with correct discrimination rate more than 90%. Furthermore, spectral distribution of sky radiance can also be estimated at every pixel, and estimated ones are consistent with those from spectrometer and those from radiative transfer simulations under various sky conditions in a wavelength range of 430-680 nm with mean biases lower than 3% and bias standard deviations smaller than 1%.

  12. 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)

    SciTech Connect

    Murcray, F.; Stephen, T.; Kosters, J.

    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).

  13. The spectral amplification effect of clouds to the night sky radiance in Madrid

    NASA Astrophysics Data System (ADS)

    Aubé, M.; Kocifaj, M.; Zamorano, J.; Solano Lamphar, H. A.; Sanchez de Miguel, A.

    2016-09-01

    Artificial Light at Night (ALAN) may have various environmental impacts ranging from compromising the visibility of astronomical objects to the perturbation of circadian cycles in animals and humans. In the past much research has been carried out to study the impact of ALAN on the radiance of the night sky during clear sky conditions. This was mainly justified by the need for a better understanding of the behavior of ALAN propagation into the environment in order to protect world-class astronomical facilities. More recently, alongside to the threat to the natural starry sky, many issues have emerged from the biological science community. It has been shown that, nearby or inside cities, the presence of cloud cover generally acts as an amplifier for artificial sky radiance while clouds behave as attenuators for remote observers. In this paper we show the spectral behavior of the zenith sky radiance amplification factor exerted by clouds inside a city. We compare in-situ measurements made with the spectrometer SAND-4 with a numerical model applied to the specific geographical context of the Universidad Complutense de Madrid in Spain.

  14. Simulated radiance profiles for automating the interpretation of airborne passive multi-spectral infrared images.

    PubMed

    Sulub, Yusuf; Small, Gary W

    2008-10-01

    Methodology is developed for simulating the radiance profiles acquired from airborne passive multispectral infrared imaging measurements of ground sources of volatile organic compounds (VOCs). The simulation model allows the superposition of pure-component laboratory spectra of VOCs onto spectral backgrounds that simulate those acquired during field measurements conducted with a downward-looking infrared line scanner mounted on an aircraft flying at an altitude of 2000-3000 ft (approximately 600-900 m). Wavelength selectivity in the line scanner is accomplished through the use of a multichannel Hg:Cd:Te detector with up to 16 integrated optical filters. These filters allow the detection of absorption and emission signatures of VOCs superimposed on the upwelling infrared background radiance within the instrumental field of view (FOV). By combining simulated radiance profiles containing analyte signatures with field-collected background signatures, supervised pattern recognition methods can be employed to train automated classifiers for use in detecting the signatures of VOCs during field measurements. The targeted application for this methodology is the use of the imaging system to detect releases of VOCs during emergency response scenarios. In the work described here, the simulation model is combined with piecewise linear discriminant analysis to build automated classifiers for detecting ethanol and methanol. Field data collected during controlled releases of ethanol, as well as during a methanol release from an industrial facility, are used to evaluate the methodology.

  15. Direct estimate of methane radiative forcing by use of nadir spectral radiances.

    PubMed

    Chazette, P; Clerbaux, C; Mégie, G

    1998-05-20

    Direct determination of the radiative forcing of trace gases will be made possible by use of the next generation of nadir-looking spaceborne instruments that provide measurements of atmospheric radiances in the infrared spectral range with improved spectral and spatial resolution. An inversion statistical method has thus been developed and applied to the direct determination of the radiative forcing of methane, based on such instruments as the Fourier-transform Interferometric Monitor for Greenhouse Gases launched onboard the Japanese Advanced Earth Observing Satellite in 1996 and the Infrared Atmospheric Sounding Interferometer planned for the European polar platform Meteorological Operational Satellite in 2000. The method is based on simple statistical laws that directly relate the measured radiances to the radiative forcing by use of an a priori selection of appropriate spectral intervals and global modeling of methane spatial variations. This procedure avoids the use of an indirect determination based on an inversion process that requires precise knowledge of the methane vertical profiles throughout the troposphere. The overall accuracy and precision of this new algorithm are studied, and interfering gases and instrumental characteristics are taken into account. It is shown that radiative forcing can be determined at high horizontal spatial resolution with a precision better than 7% in cloud-free conditions and with well-known surface properties.

  16. An Investigation of Mars NIR Spectral Features using Absolutely Calibrated Images

    NASA Astrophysics Data System (ADS)

    Klassen, D. R.; Bell, J. F., III

    1998-09-01

    We used the NSFCAM 256x256 InSb array camera at the NASA Infrared Telescope Facility to gather near-infrared (NIR) spectral image sets of Mars through the 1995 opposition. In previous studies with these data [1-6] we noted several interesting spectral features, some of which are diagnostic volatile absorption bands that allow the discrimination between CO_2 or H_2O ices. Band depth maps of these regions show polar and morning and evening limb ices composed of water and some indication of polar CO_2 ices. Other features, near 3.33 and 3.4\\micron, appear to be confined to particular geographic regions; specifically Syrtis Major. However, the images used in these previous studies were calibrated to either the disk average or only to a rough scaled reflectance by simple division by solar-type star data gathered at the same time as the images. This only allowed determinations of spectral features either relative to some global average of the feature, or to some unit not directly comparable to other published data. For at least three of our observation nights the conditions and data are sufficient to absolutely calibrate the images to radiance factors. For this work we reinvestigate the spectra and band depth mapping results using these absolutely calibrated images. In general we find that bright regions have peak radiance factors of 0.5 to 0.6 at 2.25\\micron\\ and 0.3 to 0.4 at 3.5\\micron; dark regions have radiance factors of 0.2 to 0.25 at 2.25\\micron\\ and 0.1 to 0.15 at 3.5\\micron. Overall, precision errors are about 0.025 in radiance factor and absolute errors are at the 10-15% level. These results are consistent with previous studies that found radiance factors of 0.35 in Tharsis, 0.47 in Elysium, and 0.26 in dark regions at 2.25\\micron\\ [7,8] and 0.3 in bright regions and 0.1 in dark regions at 3.5\\micron\\ [8]. These absolute flux values will allow direct comparison of these results to radiative transfer models of the behavior of the surface and

  17. Error Budget for a Calibration Demonstration System for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2013-01-01

    A goal of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is to observe highaccuracy, long-term climate change trends over decadal time scales. The key to such a goal is to improving the accuracy of SI traceable absolute calibration across infrared and reflected solar wavelengths allowing climate change to be separated from the limit of natural variability. The advances required to reach on-orbit absolute accuracy to allow climate change observations to survive data gaps exist at NIST in the laboratory, but still need demonstration that the advances can move successfully from to NASA and/or instrument vendor capabilities for spaceborne instruments. The current work describes the radiometric calibration error budget for the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. The goal of the CDS is to allow the testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. The resulting SI-traceable error budget for reflectance retrieval using solar irradiance as a reference and methods for laboratory-based, absolute calibration suitable for climatequality data collections is given. Key components in the error budget are geometry differences between the solar and earth views, knowledge of attenuator behavior when viewing the sun, and sensor behavior such as detector linearity and noise behavior. Methods for demonstrating this error budget are also presented.

  18. REDSHIFTS, WIDTHS, AND RADIANCES OF SPECTRAL LINES EMITTED BY THE SOLAR TRANSITION REGION

    SciTech Connect

    Feldman, U.; Dammasch, I. E.; Doschek, G. A.

    2011-12-20

    A long-standing problem in understanding the physics of the transition region has been the ubiquitous redshifts of transition region ultraviolet spectral lines relative to chromospheric emission lines, a result known since the Skylab era. Extended spectral scans performed for various regions of the solar disk by the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory contain thousands of line profiles per study and allow a thorough investigation of the redshift phenomenon. In using these data from seven distinct disk areas made in lines spanning the chromosphere to coronal temperature range, we derive a relationship between Doppler wavelength shifts and radiances and a relationship between line widths and radiances. While chromospheric and coronal lines emitted by very bright plasmas may in some cases show pronounced redshifts, transition-region lines predominantly show redshifts everywhere in the quiet Sun and in active regions. In coronal holes, however, they display a reduced shift, which at times altogether disappears. The observations and the findings will be described, and possible explanations will be considered.

  19. Test Plan for a Calibration Demonstration System for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; Hair, Jason; McAndrew, Brendan; Daw, Adrian; Jennings, Donald; Rabin, Douglas

    2012-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe high-accuracy, long-term climate change trends and to use decadal change observations as the most critical method to determine the accuracy of climate change. One of the major objectives of CLARREO is to advance the accuracy of SI traceable absolute calibration at infrared and reflected solar wavelengths. This advance is required to reach the on-orbit absolute accuracy required to allow climate change observations to survive data gaps while remaining sufficiently accurate to observe climate change to within the uncertainty of the limit of natural variability. While these capabilities exist at NIST in the laboratory, there is a need to demonstrate that it can move successfully from NIST to NASA and/or instrument vendor capabilities for future spaceborne instruments. The current work describes the test plan for the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. The goal of the CDS is to allow the testing and evaluation of calibration approaches , alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. The end result of efforts with the SOLARIS CDS will be an SI-traceable error budget for reflectance retrieval using solar irradiance as a reference and methods for laboratory-based, absolute calibration suitable for climate-quality data collections. The CLARREO mission addresses the need to observe high-accuracy, long-term climate change trends and advance the accuracy of SI traceable absolute calibration. The current work describes the test plan for the SOLARIS which is the calibration demonstration

  20. Comparison of Spectral Radiance Calibration Techniques Used for Backscatter Ultraviolet Satellite Instruments

    NASA Technical Reports Server (NTRS)

    Kowalewski, Matthew G.; Janz, Scott

    2014-01-01

    Methods for determining the absolute radiometric calibration sensitivities of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration errors. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV (SSBUV), Total Ozone Mapping Spectrometer (TOMS), Ozone Mapping Instrument (OMI), and Global Ozone Monitoring Experiment 2 (GOME-2) using standardized procedures traceable to national standards. These sphere-based sensitivities agree to within three percent [k equals 2] relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary radiance calibration method for BUV instruments. The uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Centers Radiometric Calibration and Development Laboratory is shown to be 4 percent at 250nm [k equals 2] when using a single traceable calibration standard. Significant reduction in the uncertainty of nearly 1 percent is demonstrated when multiple calibration standards are used.

  1. Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) Earth limb spectral measurements, calibration, and atmospheric O3, HNO3, CFC-12, and CFC-11 profile retrieval

    NASA Astrophysics Data System (ADS)

    Bingham, G. E.; Zhou, D. K.; Bartschi, B. Y.; Anderson, G. P.; Smith, D. R.; Chetwynd, J. H.; Nadile, R. M.

    1997-02-01

    During the Space Transportation System 39 (STS 39) flight of April 28 to May 6, 1991, the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) measured spectral and spatial ("Earth limb scan") distributions of the atmospheric infrared (IR) emissions using a Michelson interferometer. The IR spectral radiant emissions from the greenhouse gases were collected at a shuttle altitude of 260 km in the 9-13 μm atmosphere infrared window. Before and after the flight, the response of CIRRIS 1A to the IR spectral emission sources was calibrated using absolute and spectral source types. The Fast Atmospheric Signature Code 3, which used the HITRAN92 database and predetermined temperature-pressure profiles from the National Meteorological Center, was used in an onion-peeling routine to retrieve gas concentrations from absolutely calibrated spectral data (moderate resolution ˜1.0 cm-1). Vertical profiles of O3, HNO3, CFC-12, and CFC-11 are presented. An error analysis is presented to show the quality of the measured spectral data and the accuracy of these retrieval results. The concentrations of CFC-11 (3.0×10-4 ppmv) and CFC-12 (4.9×10-4 ppmv) in the tropopause region are consistent with a global flux increment rate of about 5% yr-1. The observed concentrations of HNO3 are consistent with previous reports for a relatively clean stratosphere.

  2. From Hubble's Next Generation Spectral Library (NGSL) to Absolute Fluxes

    NASA Astrophysics Data System (ADS)

    Heap, S. R.; Lindler, D.

    2016-05-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R˜1000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.03 μ. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsl/. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We have therefore developed an observing procedure, data-reduction procedure, and correction algorithms that should yield fluxes with uncertainties less than 1%.

  3. The QME AERI LBLRTM: A Closure Experiment for Downwelling High Spectral Resolution Infrared Radiance.

    NASA Astrophysics Data System (ADS)

    Turner, D. D.; Tobin, D. C.; Clough, S. A.; Brown, P. D.; Ellingson, R. G.; Mlawer, E. J.; Knuteson, R. O.; Revercomb, H. E.; Shippert, T. R.; Smith, W. L.; Shephard, M. W.

    2004-11-01

    Research funded by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program has led to significant improvements in longwave radiative transfer modeling over the last decade. These improvements, which have generally come in small incremental changes, were made primarily in the water vapor self- and foreign-broadened continuum and the water vapor absorption line parameters. These changes, when taken as a whole, result in up to a 6 W m-2 improvement in the modeled clear-sky downwelling longwave radiative flux at the surface and significantly better agreement with spectral observations. This paper provides an overview of the history of ARM with regard to clear-sky longwave radiative transfer, and analyzes remaining related uncertainties in the ARM state-of-the-art Line-by-Line Radiative Transfer Model (LBLRTM).A quality measurement experiment (QME) for the downwelling infrared radiance at the ARM Southern Great Plains site has been ongoing since 1994. This experiment has three objectives: 1) to validate and improve the absorption models and spectral line parameters used in line-by-line radiative transfer models, 2) to assess the ability to define the atmospheric state, and 3) to assess the quality of the radiance observations that serve as ground truth for the model. Analysis of data from 1994 to 1997 made significant contributions to optimizing the QME, but is limited by small but significant uncertainties and deficiencies in the atmospheric state and radiance observations. This paper concentrates on the analysis of QME data from 1998 to 2001, wherein the data have been carefully selected to address the uncertainties in the 1994 97 dataset. Analysis of this newer dataset suggests that the representation of self-broadened water vapor continuum absorption is 3% 8% too strong in the 750 1000 cm-1 region. The dataset also provides information on the accuracy of the self- and foreign-broadened continuum absorption in the 1100 1300 cm-1 region. After

  4. Reflectance Mechanism and Biophysical Characteristics of a Boreal Forest through Analyses of Airborne Spectral Radiance Observations

    NASA Astrophysics Data System (ADS)

    Dim, J. R.; Kajiwara, K.; Honda, Y.

    2006-12-01

    Hyperspectral radiance data were recorded from airborne observations simultaneously with whiteboard measurements in order to identify the reflectance mechanism patterns of the vegetation of a boreal forest located in the northern part of Japan. Because the degree of reflectance of a leaf depends on the leaf surface properties and internal structure as well as its water content and biochemical composition, the canopy reflectance signature may be used to understand the vegetation growing conditions and influencing factors. In this study a radio-controlled helicopter flying at a height just above the trees and bearing a portable spectral radiometer, a digital camera, a video camera and a laser scanner, was used to obtain the vegetation spectral reflectance data and biophysical characteristics of this forest. Spectral reflectance discrimination analyses show that vegetation types of the study field can be well distinguished. And, the amount of vegetation reflectance tends to decrease with the complexity of the canopy structure, as a result of increasing radiation scattering of these surfaces. The mechanism of multiple reflection was suggested to explain the relation between reflectance and irregularities of the canopy structures.

  5. First derivative versus absolute spectral reflectance of citrus varieties

    NASA Astrophysics Data System (ADS)

    Blazquez, Carlos H.; Nigg, H. N.; Hedley, Lou E.; Ramos, L. E.; Sorrell, R. W.; Simpson, S. E.

    1996-06-01

    Spectral reflectance measurements from 400 to 800 nm were taken from immature and mature leaves of grapefruit ('McCarty' and 'Rio Red'), 'Minneola' tangelo, 'Satsuma' mandarin, 'Dancy' tangerine, 'Nagami' oval kumquat, and 'Valencia' sweet orange, at the Florida Citrus Arboretum, Division of Plant Industry, Winter Haven, Florida. Immature and mature leaves of 'Minneola' tangelo had greater percent reflectance in the 400 to 800 nm range than the other varieties and leaf ages measured. The slope of the citrus spectral curves in the 800 nm range was not as sharp as conventional spectrometers, but had a much higher reflectance value than those obtained with a DK-2 spectrometer. Statistical analyses of absolute spectral data yielded significant differences between mature and immature leaves and between varieties. First derivative data analyses did not yield significant differences between varieties.

  6. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%–0.68% (k  =  2).

  7. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%-0.68% (k  =  2).

  8. Characterization of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) ability to serve as an infrared satellite intercalibration reference

    NASA Astrophysics Data System (ADS)

    Tobin, David; Holz, Robert; Nagle, Fred; Revercomb, Henry

    2016-04-01

    Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a future mission employing an infrared spectrometer with unprecedented calibration accuracy and the ability to assess its calibration on-orbit using a novel verification system. Utilizing this capability for satellite intercalibration is a primary objective of the mission. This paper presents a new infrared intercalibration methodology that minimizes the intercalibration uncertainties and provides uncertainty estimates resulting from the scene variability and instrument noise. Results of a simulation study to characterize realistic spatial and temporal matching differences for simultaneous nadir overpasses (SNOs) of CLARREO and existing hyperspectral sounders are presented. This study, along with experience with intercalibration of real data, finds that intercalibration uncertainties are minimized when the SNOs are not screened for sky conditions but instead weighted based on the observed scene variability. Intercalibration performance is investigated for a 90° polar orbit mission and for a Pathfinder mission on the International Space Station, for various potential CLARREO footprint sizes, and as a function of mission length, scene brightness temperature, and wavelength. The results are encouraging and suggest that biases between CLARREO and sounder observations can be determined with low uncertainty and with high time frequency during a CLARREO mission. For example, the simulations suggest that a CLARREO footprint of 50 to 100 km in diameter is optimal for intercalibration, and that the 3 sigma intercalibration uncertainty is less than 0.1 K for channels at infrared window wavelengths using 2 months of accumulated SNOs, and for more absorbing channels with less scene variability the uncertainties are less than 50 mK.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Estimation of aerosol single scattering albedo from solar direct spectral radiance and total broadband irradiances measured in China

    NASA Astrophysics Data System (ADS)

    Zhao, Fengsheng; Li, Zhanqing

    2007-11-01

    Aerosol single scattering albedo (ωo) is a primary factor dictating aerosol radiative effect. Ground-based remote sensing of ωo has been employed most widely using spectral sky radiance measurements made from a scanning Sun photometer. Reliable results can be achieved for high aerosol loadings and for solar zenith angle >50°. This study presents an alternative method using spectral direct radiance measurements or aerosol optical depths together with total sky irradiance to retrieve ωo. The method does not require sky radiance data that can only be acquired by the expensive scanning Sun photometer. The method is evaluated using extensive measurements by a suite of instruments deployed in northern China under the East Asian Study of Tropospheric Aerosols: An International Regional Experiment (EAST-AIRE) project. The sensitivities of the retrieval to various uncertain factors were first examined by means of radiative transfer simulations. It was found the retrieval is most sensitive to cloud screening, total irradiance and the Angstrom Exponent (AE), but only weakly depends on surface albedo and the fine structure of aerosol size distribution. Using 1 year of rigorously screened clear-sky measurements made at the Xianghe site, the retrieved ωo values were found to agree with those retrieved from the Cimel Sun photometer by the AERONET method to within ˜0.03 (RMS), and ˜0.003 (mean bias). As part of the differences originate from different sky views seen by the Sun photometers and pyranometer under comparison, a further test was conducted by using total sky irradiances simulated with the retrieved aerosol properties from the AERONET. The resulting estimates of ωo agree to within 0.01-0.02 (RMS differences) and 0.002-0.003 (mean bias). These values are better measure of the true retrieval uncertainties, as they are free from any data mismatch. The characteristics of ωo retrievals were discussed.

  11. An integrated model of soil-canopy spectral radiances, photosynthesis, fluorescence, temperature and energy balance

    NASA Astrophysics Data System (ADS)

    van der Tol, C.; Verhoef, W.; Timmermans, J.; Verhoef, A.; Su, Z.

    2009-12-01

    This paper presents the model SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes), which is a vertical (1-D) integrated radiative transfer and energy balance model. The model links visible to thermal infrared radiance spectra (0.4 to 50 μm) as observed above the canopy to the fluxes of water, heat and carbon dioxide, as a function of vegetation structure, and the vertical profiles of temperature. Output of the model is the spectrum of outgoing radiation in the viewing direction and the turbulent heat fluxes, photosynthesis and chlorophyll fluorescence. A special routine is dedicated to the calculation of photosynthesis rate and chlorophyll fluorescence at the leaf level as a function of net radiation and leaf temperature. The fluorescence contributions from individual leaves are integrated over the canopy layer to calculate top-of-canopy fluorescence. The calculation of radiative transfer and the energy balance is fully integrated, allowing for feedback between leaf temperatures, leaf chlorophyll fluorescence and radiative fluxes. Leaf temperatures are calculated on the basis of energy balance closure. Model simulations were evaluated against observations reported in the literature and against data collected during field campaigns. These evaluations showed that SCOPE is able to reproduce realistic radiance spectra, directional radiance and energy balance fluxes. The model may be applied for the design of algorithms for the retrieval of evapotranspiration from optical and thermal earth observation data, for validation of existing methods to monitor vegetation functioning, to help interpret canopy fluorescence measurements, and to study the relationships between synoptic observations with diurnally integrated quantities. The model has been implemented in Matlab and has a modular design, thus allowing for great flexibility and scalability.

  12. Comparisons of brightness temperature measurements and calculations obtained during the spectral radiance experiment

    SciTech Connect

    Han, Y.; Snider, J.B.; Westwater, E.R.; Melfi, S.H.; Ferrare, R.A.

    1995-04-01

    In radiometric remote sensing of the atmosphere, the ability to calculate radiances from underlying state variables is fundamental. To infer temperature and water vapor profiles from satellite- or ground-based radiometers, one must determine cloud-free regions and then calculate clear-sky radiance emerging from the top of the earth`s atmosphere from the underlying profiles of temperature and water vapor. Equally important is the validation of the radiometric retrievals. Usually such validation is made by comparing retrievals with profiles derived from other sensors. Traditionally, such {open_quotes}forward model{close_quotes} calculations and validations have coupled radiosonde observations of the state variables with detailed absorption and radiative transfer models. However, for a variety of reasons, radiosonde moisture measurements are not always satisfactory, especially during low humidity conditions or when there are large horizontal or temporal gradients in the humidity structure. A recent alternative to radiosonde moisture measurements is Raman lidar. The Raman lidar provides humidity measurements with temporal and spatial resolution far superior to radiosonde measurements. In November-December 1991, a substantial number of remote sensor and in-situ instruments were operated together in Coffeyville, Kansas, during the First ISCCP Regional Experiment (FIRE) 11. Included in the suite of instruments were (1) the Environmental Technology Laboratory`s (ETL) three-channel microwave radiometer, (2) the NASA/Goddard Space Flight Center`s (GSFC) Raman lidar, (3) ETL`s radio acoustic sounding system (RASS), and (4) frequent research-quality radiosondes. The Raman lidar operated only at night, and this portion of the experiment focused on cloud-free conditions. In this presentation, we present results of simultaneous microwave radiometer measurements with collocated Raman lidar measurements of water vapor over 10 nights during the experiments.

  13. Spectral radiance estimates of leaf area and leaf phytomass of small grains and native vegetation

    NASA Technical Reports Server (NTRS)

    Aase, J. K.; Brown, B. S.; Millard, J. P.

    1986-01-01

    Similarities and/or dissimilarities in radiance characteristics were studied among barley (Hordeum vulgare L.), oats (Avena fatua L.), spring and winter wheat (Triticum aestivum L.), and short-grass prairie vegetation. The site was a Williams loam soil (fine-loamy mixed, Typic Argiborolls) near Sidney, Montana. Radiances were measured with a truck-mounted radiometer. The radiometer was equipped with four wavelength bands: 0.45 to 0.52, 0.52 to 0.60, 0.63 to 0.69, and 0.76 to 0.90 micron. Airborne scanner measurements were made at an altitude of 600 m four times during the season under clear sky conditions. The airborne scanner was equipped with the same four bands as the truck-mounted radiometer plus the following: 1.00 to 1.30, 1.55 to 1.75, 2.08 to 2.35, and 10.4 to 12.5 microns. Comparisons using individual wave bands, the near IR/red, (0.76 to 0.90 micron)/(0.63 to 0.69 micron) ratio and the normalized difference vegetation index, ND = (IR - red)/(IR + red), showed that only during limited times during the growing season were some of the small grains distinguishable from one another and from native rangeland vegetation. There was a common relation for all small grains between leaf area index and green leaf phytomass and between leaf area index or green leaf phytomass and the IR/red ratio.

  14. Homomorphism between cloudy and clear spectral radiance in the 800-900-cm(-1) atmospheric window region.

    PubMed

    Masiello, Guido; Matricardi, Marco; Rizzi, Rolando; Serio, Carmine

    2002-02-20

    The sensitivity of a new algorithm for cloud detection over a sea surface has been assessed on the basis of extensive simulations of clear and cloudy radiance spectra, including water and ice and low- and high-altitude clouds. The new algorithm makes use of autocorrelation and cross correlation between an observed spectrum and either a synthetic or a laboratory spectrum and can be used to determine quantitatively the degree of homogeneity of two spectra in the 800-900-cm(-1) region (11.11-12.5 microm). The scheme is intended for high-spectral-resolution observations and could form the basis for an operational stand-alone cloud-detection algorithm for next-generation sounding spectrometers. Application of the scheme to real observations is presented and discussed.

  15. High Altitude Measurements of Radiance at High Spectral and Spatial Resolution for SIMBIOS Sensor Calibration, Validation, and Intercomparisons. Chapter 11

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Pavri, Betina; Chrien, Thomas G.

    2001-01-01

    The successful combination of data from different ocean color sensors depends on the correct interpretation of signal from each of these sensors. Ideally, the sensor measured signals are calibrated to geophysical units of spectral radiance, and sensor artifacts are removed and corrected. The calibration process resamples the signal into a common radiometric data space so that subsequent ocean color algorithms that are applied to the data are based on physical processes and are inherently sensor independent. The objective of this project is to calibrate and validate the on-orbit radiometric characteristics of Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) with underflights of NASA's calibrated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). This objective is feasible because AVIRIS measures the same spectral range as SeaWIFS at higher spectral resolution. In addition to satellite sensor underflights, the AVIRIS project has supported comparison and analysis of the radiometric calibration standards used for AVIRIS and SeaWIFS. To date, both the OCTS and SeaWIFS satellite sensors have been underflown by AVIRIS with matching spectral, spatial, geometric, radiometric, and temporal domains. The calibration and validation objective of this project is pursued for the following reasons: (1) Calibration is essential for the quantitative use of SeaWIFS and other SIMBIOS (Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies) sensor data; (2) Calibration in the laboratory of spaceborne sensors is challenging; (3) Satellite sensors are subjected aging on the ground and to trauma during launch; (4) The Earth orbit environment is significantly different than the laboratory calibration environment; (5) Through years of effort AVIRIS has been demonstrated to be well calibrated; and (6) AVIRIS can match the spectral and spatial observation characteristics near the top of the atmosphere at the time of SeaWIFS measurements.

  16. Atmospheric Emitted Radiance Interferometer (AERI) Handbook

    SciTech Connect

    Demirgian, J; Dedecker, R

    2005-01-01

    The atmospheric emitted radiance interferometer (AERI) measures the absolute infrared (IR) spectral radiance (watts per square meter per steradian per wavenumber) of the sky directly above the instrument. The spectral measurement range of the instrument is 3300 to 520 wavenumbers (cm-1) or 3-19.2 microns for the normal-range instruments and 3300 to 400 cm-1 or 3-25 microns, for the extended-range polar instruments. Spectral resolution is 1.0 cm-1. Instrument field-of-view is 1.3 degrees. A calibrated sky radiance spectrum is produced every 8 minutes in normal mode and every minute in rapid sampling mode. The actual sample scan time is 20-30 sec in rapid sampling mode with periodic gaps when the instrument is looking at the blackbodies. Rapid sampling will become available in all AERIs. Rapid sampling time will eventually be reduced to data every 20 seconds. The AERI data can be used for 1) evaluating line-by-line radiative transport codes, 2) detecting/quantifying cloud effects on ground-based measurements of infrared spectral radiance (and hence is valuable for cloud property retrievals), and 3) calculating vertical atmospheric profiles of temperature and water vapor and the detection of trace gases.

  17. Algal Accessory Pigment Detection Using AVIRIS Image-Derived Spectral Radiance Data

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Ambrosia, Vincent G.

    1996-01-01

    Visual and derivative analyses of AVIRIS spectral data can be used to detect algal accessory pigments in aquatic communities. This capability extends the use of remote sensing for the study of aquatic ecosystems by allowing detection of taxonomically significant pigment signatures which yield information about the type of algae present. Such information allows remote sensing-based assessment of aquatic ecosystem health, as in the detection of nuisance blooms of cyanobacteria or toxic blooms of dinoflagellates. Remote sensing of aquatic systems has traditionally focused on quantification of chlorophyll a, a photoreactive (and light-harvesting) pigment which is common to all algae as well as cyanobacteria (bluegreen algae). Due to the ubiquitousness of this pigment within algae, chl a is routinely measured to estimate algal biomass both during ground-truthing and using various airborne or satellite based sensors, including AVIRIS. Within the remote sensing and aquatic sciences communities, ongoing research has been performed to detect algal accessory pigments for assessment of algal population composition. This research is based on the fact that many algal accessory pigments are taxonomically significant, and all are spectrally unique. Aquatic scientists have been refining pigment analysis techniques, primarily high performance liquid chromatography, or HPLC, to detect specific pigments as a time-saving alternative to individual algal cell identifications and counts. Remote sensing scientists are investigating the use of pigment signatures to construct pigment libraries analogous to mineral spectral libraries used in geological remote sensing applications. The accessory pigment approach has been used successfully in remote sensing using data from the Thematic Mapper, low-altitude, multiple channel scanners, field spectroradiometers and the AVIRIS hyperspectral scanner. Due to spectral and spatial resolution capabilities, AVIRIS is the sensor of choice for such

  18. Using the solar elevation angle and radiance conversion to normalize forest spectral signatures

    NASA Technical Reports Server (NTRS)

    Middleton, E. M.; Lu, Y.-C.

    1984-01-01

    A number of spectral signals associated with forest cover were selected in order to test the usefulness of adjustments to Landsat MSS digital count values. The signatures were taken from 26 independent regional land cover inventories in the northeastern US. A regression analysis was conducted which revealed a significant relationship between digital count values and variation in the solar elevation angles in MSS bands four, six, and seven for deciduous forests and in all MSS bands for conifers. When signatures were adjusted for solar elevation angles and MSS sensor calibration differences, the dependence on solar elevation angle was reduced. The adjustments also significantly reduced the variance with Level II forest categories among scenes.

  19. CCPR-S1 Supplementary comparison for spectral radiance in the range of 220 nm to 2500 nm

    NASA Astrophysics Data System (ADS)

    Khlevnoy, Boris; Sapritsky, Victor; Rougie, Bernard; Gibson, Charles; Yoon, Howard; Gaertner, Arnold; Taubert, Dieter; Hartmann, Juergen

    2009-08-01

    In 1997, the Consultative Committee for Photometry and Radiometry (CCPR) initiated a supplementary comparison of spectral radiance in the wavelength range from 220 nm to 2500 nm (CCPR-S1) using tungsten strip-filament lamps as transfer standards. Five national metrology institutes (NMIs) took part in the comparison: BNM/INM (France), NIST (USA), NRC (Canada), PTB (Germany) and VNIIOFI (Russia), with VNIIOFI as the pilot laboratory. Each NMI provided the transfer lamps that were used to transfer their measurements to the pilot laboratory. The intercomparison sequence began with the participant measurements, then the pilot measurements, followed by a second set of measurements by the participant laboratory. The measurements were carried out from 1998 to 2002, with the final report completed in 2008. This paper presents the descriptions of measurement facilities and uncertainties of the participants, as well as the comparison results that were analysed in accordance with the Guidelines for CCPR Comparisons Report Preparation, and a re-evaluation of the results taking into account the instability of some of the transfer lamps. Excluding a few wavelengths, all participants agree with each other within ±1.5%. The disagreement decreases to approximately ±1.0% when the anomalous data are excluded from the analysis.

  20. Use of Spectral Radiance to Estimate In-Season Biomass and Grain Yield in Nitrogen- and Water-Stressed Corn.

    PubMed

    Osborne, S. L.; Schepers, J. S.; Francis, D. D.; Schlemmer, M. R.

    2002-01-01

    Current technologies for measuring plant water status are limited, while recently remote sensing techniques for estimating N status have increased with limited research on the interaction between the two stresses. Because plant water status methods are time-consuming and require numerous observations to characterize a field, managers could benefit from remote sensing techniques to assist in irrigation and N management decisions. A 2-yr experiment was initiated to determine specific wavelengths and/or combinations of wavelengths indicative of water stress and N deficiencies, and to evaluate these wavelengths for estimating in-season biomass and corn (Zea mays L.) grain yield. The experiment was a split-plot design with three replications. The treatment structure had five N rates (0, 45, 90, 134, and 269 kg N ha(-1)) and three water treatments [dryland, 0.5 evapotranspiration (ET), and full ET]. Canopy spectral radiance measurements (350-2500 nm) were taken at various growth stages (V6-V7, V13-V16, and V14-R1). Specific wavelengths for estimating crop biomass, N concentration, grain yield, and chlorophyll meter readings changed with growth stage and sampling date. Changes in total N and biomass in the presence of a water stress were estimated using near-infrared (NIR) reflectance and the water absorption bands. Reflectance in the green and NIR regions were used to estimate total N and biomass without water stress. Reflectance at 510, 705, and 1135 nm were found for estimating chlorophyll meter readings regardless of year or sampling date.

  1. Establishing a New NIST Facility for the Primary Realization of both Spectral Radiance and Reflectance in the Mid-and Far-Infrared

    NASA Astrophysics Data System (ADS)

    Mekhontsev, S.; Khromchenko, V.; Prokhorov, A.; Wilthan, B.; Hanssen, L.

    2009-12-01

    In the framework of the research initiative “Climate Change: Measurements & Standards”, a new primary standard facility is being established for realization of both spectral radiance and reflectance in the mid-and far-infrared. The objective of the CBS3 (which stands for Controlled Background Spectroradiometry and Spectrophotometry System) is to develop an advanced primary standard with proven accuracy and based on fundamental and reproducible physical standards to assure SI traceability. Derivation of the infrared spectral directional-hemispherical reflectance scale for materials and cavities is achieved using active control of radiation background directional-hemispherical reflectance. The measurements of diffuse reflectance will be supported for the wavelengths up to 50 micrometers, incidence angles up to 85 degrees, and temperatures from 200 K to 350 K. Derivation of spectral radiance and radiance temperature scale is based on use of primary blackbody sources, whose emissivity is defined via reflectometry as mentioned above, and temperature is defined by fundamental and reproducible properties of phase change processes of pure substances, including mercury, water and gallium. Along with derivation and dissemination of spectral radiance and reflectance scales, the facility will support additional tests for user sources, sensors and components, as well as continue support of NIST TXR radiometer. Controlled radiation background feature will also be used for prediction of performance of NIST transfer standards and user payloads at different environmental conditions. Specialized instrumentation will be developed, including primary blackbody sources, a test chamber, a far IR reflectometer, and a spectral comparator, as well as transfer standards to ensure dissemination of radiometric and spectrophotometric scales and their validation via international comparisons. A demonstration study and the conceptual design of core components of the facility have been

  2. Radiance Covariance and Climate Models

    NASA Technical Reports Server (NTRS)

    Haskins, R.; Goody, R.; Chen, L.

    1998-01-01

    Spectral Empirical Orhtogonal Functions (EOFs) derived from the covariance of satellite radiance spectra may be interpreted in terms of the vertical distribution of the covariance of temperature, water vapor, and clouds. The purpose of the investigation is to demonstrate the important constraints that resolved spectral radiances can place upon climate models.

  3. LADAR performance simulations with a high spectral resolution atmospheric transmittance and radiance model: LEEDR

    NASA Astrophysics Data System (ADS)

    Roth, Benjamin D.; Fiorino, Steven T.

    2012-06-01

    In this study of atmospheric effects on Geiger Mode laser ranging and detection (LADAR), the parameter space is explored primarily using the Air Force Institute of Technology Center for Directed Energy's (AFIT/CDE) Laser Environmental Effects Definition and Reference (LEEDR) code. The expected performance of LADAR systems is assessed at operationally representative wavelengths of 1.064, 1.56 and 2.039 μm at a number of locations worldwide. Signal attenuation and background noise are characterized using LEEDR. These results are compared to standard atmosphere and Fast Atmospheric Signature Code (FASCODE) assessments. Scenarios evaluated are based on air-toground engagements including both down looking oblique and vertical geometries in which anticipated clear air aerosols are expected to occur. Engagement geometry variations are considered to determine optimum employment techniques to exploit or defeat the environmental conditions. Results, presented primarily in the form of worldwide plots of notional signal to noise ratios, show a significant climate dependence, but large variances between climatological and standard atmosphere assessments. An overall average absolute mean difference ratio of 1.03 is found when climatological signal-to-noise ratios at 40 locations are compared to their equivalent standard atmosphere assessment. Atmospheric transmission is shown to not always correlate with signal-to-noise ratios between different atmosphere profiles. Allowing aerosols to swell with relative humidity proves to be significant especially for up looking geometries reducing the signal-to-noise ratio several orders of magnitude. Turbulence blurring effects that impact tracking and imaging show that the LADAR system has little capability at a 50km range yet the turbulence has little impact at a 3km range.

  4. The solar absolute spectral irradiance 1150-3173 A - May 17, 1982

    NASA Technical Reports Server (NTRS)

    Mount, G. H.; Rottman, G. J.

    1983-01-01

    The full-disk solar spectral irradiance in the spectral range 1150-3173 A was obtained from a rocket observation above White Sands Missile Range, NM, on May 17, 1982, half way in time between solar maximum and solar minimum. Comparison with measurements made during solar maximum in 1980 indicate a large decrease in the absolute solar irradiance at wavelengths below 1900 A to approximately solar minimum values. No change above 1900 A from solar maximum to this flight was observed to within the errors of the measurements. Irradiance values lower than the Broadfoot results in the 2100-2500 A spectral range are found, but excellent agreement with Broadfoot between 2500 and 3173 A is found. The absolute calibration of the instruments for this flight was accomplished at the National Bureau of Standards Synchrotron Radiation Facility which significantly improves calibration of solar measurements made in this spectral region.

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

    SciTech Connect

    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.

  6. Assessing the contribution from different parts of Canary islands to the hemispheric spectral sky radiance levels over European Northern Observatories

    NASA Astrophysics Data System (ADS)

    Aubé, Martin

    2015-03-01

    In this paper, we suggest to use a sky radiance model which accounts for heterogeneous distribution of light fixtures, their photometry, the ground reflectance and topography, to infer the point to point contribution of Canary Islands to the artificial sky radiance at Observatorio del Teide (Tenerife) and Observatorio Roque de los Muchachos (La Palma). In-situ hyperspectral sky radiance measurements, acquired on site in 2010, have been used to calibrate the model and to evaluate its inherent error. We aim to identify and characterize zones at which any lighting level increase or decrease may have a larger impact on light pollution at both European Northern Observatory sites, and then help to control and/or reduce their light pollution levels. This innovative methodology, can then be seen as a high level decision tool to help local authorities to restrict or reduce light pollution with the objective of protecting research class astronomical sites.

  7. Absolute radiometric calibration of advanced remote sensing systems

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1982-01-01

    The distinction between the uses of relative and absolute spectroradiometric calibration of remote sensing systems is discussed. The advantages of detector-based absolute calibration are described, and the categories of relative and absolute system calibrations are listed. The limitations and problems associated with three common methods used for the absolute calibration of remote sensing systems are addressed. Two methods are proposed for the in-flight absolute calibration of advanced multispectral linear array systems. One makes use of a sun-illuminated panel in front of the sensor, the radiance of which is monitored by a spectrally flat pyroelectric radiometer. The other uses a large, uniform, high-radiance reference ground surface. The ground and atmospheric measurements required as input to a radiative transfer program to predict the radiance level at the entrance pupil of the orbital sensor are discussed, and the ground instrumentation is described.

  8. Experimental feasibility of the airborne measurement of absolute oil fluorescence spectral conversion efficiency

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1983-01-01

    Airborne lidar oil spill experiments carried out to determine the practicability of the AOFSCE (absolute oil fluorescence spectral conversion efficiency) computational model are described. The results reveal that the model is suitable over a considerable range of oil film thicknesses provided the fluorescence efficiency of the oil does not approach the minimum detection sensitivity limitations of the lidar system. Separate airborne lidar experiments to demonstrate measurement of the water column Raman conversion efficiency are also conducted to ascertain the ultimate feasibility of converting such relative oil fluorescence to absolute values. Whereas the AOFSCE model is seen as highly promising, further airborne water column Raman conversion efficiency experiments with improved temporal or depth-resolved waveform calibration and software deconvolution techniques are thought necessary for a final determination of suitability.

  9. Retrieval of atmospheric-temperature and water-vapor profiles by use of combined satellite and ground-based infrared spectral-radiance measurements.

    PubMed

    Ho, Shu-Peng; Smith, William L; Huang, Hung-Lung

    2002-07-10

    A nonlinear sounding retrieval algorithm is used to produce vertical-temperature and water-vapor profiles from coincident observations taken by the airborne High-resolution Interferometer Sounder (HIS) and the ground-based Atmospheric Emitted Radiance Interferometer (AERI) during the SUbsonic Contrails and Clouds Effects Special Study (SUCCESS). Also, clear sky Geostationary Operational Environmental Satellite (GOES) and AERI radiance measurements, achieved on a daily real-time basis at the Department of Energy's Oklahoma CART (Cloud and Radiation Testbed) site, are used to demonstrate the current profiling capability by use of simultaneous geostationary satellite and ground-based remote sensing observations under clear-sky conditions. The discrepancy principle, a method to find the proper smoothing parameters from the minimum value between the normalized spectral residual norm and the a priori upper bound, is used to demonstrate the feasibility and effectiveness of on-line simultaneous tuning of the multiple weighting and smoothing parameters from the combined satellite/airborne and ground-based measurements for the temperature and water-vapor retrieval in this nonlinear-retrieval process. An objective method to determine the degrees of freedom (d.f.) of the observation signal is derived. The d.f. of the radiance signal for the combined GOES and AERI measurements is larger than that for either instrument alone; while the d.f. of the observation signal for the combined GOES and AERI measurements is larger than that for either instrument alone and of the combined GOES and AERI measurements. The use of simultaneous clear-sky AERI and GOES data now provides improved vertical temperature and moisture soundings on an hourly basis for use in the Atmospheric Radiation Measurement program [J. Appl. Meteorol. 37, 875 (1998)]. PMID:12141504

  10. Retrieval of atmospheric-temperature and water-vapor profiles by use of combined satellite and ground-based infrared spectral-radiance measurements.

    PubMed

    Ho, Shu-Peng; Smith, William L; Huang, Hung-Lung

    2002-07-10

    A nonlinear sounding retrieval algorithm is used to produce vertical-temperature and water-vapor profiles from coincident observations taken by the airborne High-resolution Interferometer Sounder (HIS) and the ground-based Atmospheric Emitted Radiance Interferometer (AERI) during the SUbsonic Contrails and Clouds Effects Special Study (SUCCESS). Also, clear sky Geostationary Operational Environmental Satellite (GOES) and AERI radiance measurements, achieved on a daily real-time basis at the Department of Energy's Oklahoma CART (Cloud and Radiation Testbed) site, are used to demonstrate the current profiling capability by use of simultaneous geostationary satellite and ground-based remote sensing observations under clear-sky conditions. The discrepancy principle, a method to find the proper smoothing parameters from the minimum value between the normalized spectral residual norm and the a priori upper bound, is used to demonstrate the feasibility and effectiveness of on-line simultaneous tuning of the multiple weighting and smoothing parameters from the combined satellite/airborne and ground-based measurements for the temperature and water-vapor retrieval in this nonlinear-retrieval process. An objective method to determine the degrees of freedom (d.f.) of the observation signal is derived. The d.f. of the radiance signal for the combined GOES and AERI measurements is larger than that for either instrument alone; while the d.f. of the observation signal for the combined GOES and AERI measurements is larger than that for either instrument alone and of the combined GOES and AERI measurements. The use of simultaneous clear-sky AERI and GOES data now provides improved vertical temperature and moisture soundings on an hourly basis for use in the Atmospheric Radiation Measurement program [J. Appl. Meteorol. 37, 875 (1998)].

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

    SciTech Connect

    Hauchecorne, A.; Meftah, M.; Irbah, A.; Hochedez, J.-F.

    2014-03-10

    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.

  12. Absolute spectral irradiance measurements of lightning from 375 to 880 nm

    NASA Technical Reports Server (NTRS)

    Orville, R. E.; Henderson, R. W.

    1984-01-01

    The time-integrated emissions from cloud-to-ground lightning have been recorded in the 375-880 nm region, using a spectrometer-detector and multichannel analyzer system capable of absolute spectral irradiance measurements. A schematic drawing of the detector-analyzer system is presented, and the experimental setup is described. A total of ten flashes containing 46 individual strikes were recorded and compared to recordings of 500 flashes from 1981. The average spectral irradiance from 375 to 695 nm for flashes at about 15 km was 3.5 x 10 to the -5th J/sq m per stroke with a standard deviation of 2.0 x 10 to the -5th and a range from 0.7 x 10 to the 0.7-6.8 x 10 to the -5th J/sq m per stroke. The average stroke spectra irradiance from 650 to 880 nm for the same strokes was 1.2 x 10 to the -5th, with a standard deviation of 0.7 x 10 to the -5th and a range from 0.5 to 3.2 x 10 to the -5th J/sq m per stroke. A summary table of spectral irradiance values in 50 nm increment is presented. Analysis of the spectral emission data show that unresolved neutral hydrogen lines (NI) at 744.2 nm were more intense than H-alpha emission at 656.3 nm. The strong emission of a flash with a continuing current was identified as cyanogen (CN) emission.

  13. Absolute intensities of CO2 lines in the 3140-3410/cm spectral region

    NASA Technical Reports Server (NTRS)

    Benner, D. Chris; Devi, V. Malathy; Ferry-Leeper, Penelope S.; Rinsland, Curtis P.

    1988-01-01

    Absolute intensities for 430 transitions belonging to eleven rotation-vibration bands of (C-12)(O-16)2, (C-13)(O-16)2, and (O-16)(C-18)(O-18) in the 3140-3410/cm spectral region have been determined by analyzing spectra recorded at 0.01/cm resolution with the Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory on Kitt Peak. The data were recorded at room temperature and low pressures (less than 10 torr) using a natural sample of carbon dioxide. Intensities were derived using a nonlinear least-squares spectral fitting procedure, and the values obtained for each band have been analyzed to determine the vibrational band intensity and nonrigid rotor coefficients. An alternative mathematical formulation is shown in the case of bands for which the Coriolis effect is large and the Q-branch line intensities were not determinable either because they were severely blended or absent from the spectra. Comparison are made between the results obtained in this study and other published values.

  14. Absolute intensities of CO(2) lines in the 3140-3410-cm(-1) spectral region.

    PubMed

    Benner, D C; Devi, V M; Rinsland, C P; Ferry-Leeper, P S

    1988-04-15

    Absolute intensities for 430 transitions belonging to eleven rotation-vibration bands of (12)C(16)O(2),(13)C(16)O(2) and(16)O(12)C(18)O in the 3140-3410-cm(-1) spectral region have been determined by analyzing spectra recorded at 0.01-cm(-1) resolution with the Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory on Kitt Peak. The data were recorded at room temperature and low pressures (<10 Torr) using a natural sample of carbon dioxide. Intensities were derived using a nonlinear least-squares spectral fitting procedure, and the values obtained for each band have been analyzed to determine the vibrational band intensity and nonrigid rotor coefficients. An alternative mathematical formulation is shown in the case of bands for which the Coriolis effect is large and the Q-branch line intensities were not determinate either because they were severely blended or absent from the spectra. Comparisons are made between the results obtained in this study and other published values.

  15. Generalized Effective Radiance Temperature

    NASA Astrophysics Data System (ADS)

    Yuan, Z.

    2015-12-01

    Radiance temperature is one of the most important and widely used concepts in radiation thermometry. The usual definition of radiance temperature does not strictly apply for complex situations, such as when surrounding radiation is non-negligible or when corrections are applied to measurements made using an inappropriate emissivity setting. A novel concept, generalized effective radiance temperature (GERT), that adopts a graybody as the reference radiator is proposed in this study to express and explain the actual measurands that exist extensively in practical radiation thermometry applications; for example, a measurement result by a spectral-band radiation thermometer whose instrumental emissivity setting is less than 1. An effective wavelength approach has been developed to elucidate the relationship between a thermometer-dependent temperature (reading from an actual spectral-band radiation thermometer) and the object-side parameter GERT. The characteristics of GERT and the effective wavelength of a GERT measurement are discussed. Choosing an arbitrary emissivity setting to correct for the emissivity of a real target is equivalent to using this value as the emissivity of the reference graybody of the GERT. The GERT can be used in calibrations of both sources and thermometers.

  16. Prelaunch absolute radiometric calibration of LANDSAT-4 protoflight Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Ball, D. L.; Leung, K. C.; Walker, J. A.

    1984-01-01

    Results are summarized and analyzed from several prelaunch tests with a 122 cm integrating sphere used as part of the absolute radiometric calibration experiments for the protoflight TM sensor carried on the LANDSAT-4 satellite. The calibration procedure is presented and the radiometric sensitivity of the TM is assessed. The internal calibrator and dynamic range after calibration are considered. Tables show dynamic range after ground processing, spectral radiance to digital number and digital number to spectral radiance values for TM bands 1, 2, 3, 4, 5, 7 and for channel 4 of band 6.

  17. Effects of inelastic radiative processes on the determination of water-leaving spectral radiance from extrapolation of underwater near-surface measurements.

    PubMed

    Li, Linhai; Stramski, Dariusz; Reynolds, Rick A

    2016-09-01

    Extrapolation of near-surface underwater measurements is the most common method to estimate the water-leaving spectral radiance, Lw(λ) (where λ is the light wavelength in vacuum), and remote-sensing reflectance, Rrs(λ), for validation and vicarious calibration of satellite sensors, as well as for ocean color algorithm development. However, uncertainties in Lw(λ) arising from the extrapolation process have not been investigated in detail with regards to the potential influence of inelastic radiative processes, such as Raman scattering by water molecules and fluorescence by colored dissolved organic matter and chlorophyll-a. Using radiative transfer simulations, we examine high-depth resolution vertical profiles of the upwelling radiance, Lu(λ), and its diffuse attenuation coefficient, KLu (λ), within the top 10 m of the ocean surface layer and assess the uncertainties in extrapolated values of Lw(λ). The inelastic processes generally increase Lu and decrease KLu in the red and near-infrared (NIR) portion of the spectrum. Unlike KLu in the blue and green spectral bands, KLu in the red and NIR is strongly variable within the near-surface layer even in a perfectly homogeneous water column. The assumption of a constant KLu with depth that is typically employed in the extrapolation method can lead to significant errors in the estimate of Lw. These errors approach ∼100% at 900 nm, and the desired threshold of 5% accuracy or less cannot be achieved at wavelengths greater than 650 nm for underwater radiometric systems that typically take measurements at depths below 1 m. These errors can be reduced by measuring Lu within a much shallower surface layer of tens of centimeters thick or even less at near-infrared wavelengths longer than 800 nm, which suggests a

  18. Simultaneous physical retrieval of surface emissivity spectrum and atmospheric parameters from infrared atmospheric sounder interferometer spectral radiances.

    PubMed

    Masiello, Guido; Serio, Carmine

    2013-04-10

    The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water-vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand.

  19. Applications of CrIS Full Spectral Resolution Data in NWP Models to Improve the Quality Control of IR Radiance Assimilation

    NASA Astrophysics Data System (ADS)

    Zou, X.

    2015-12-01

    The Advanced Technology of Microwave Sounder (ATMS) and the Cross-track Infrared Sounder (CrIS) on board Suomi National Polar-Orbiting Partnership (SNPP) satellite provide data for profiling atmospheric temperature and moisture under all weather conditions and supporting continuing advances in data assimilation and NWP modeling. As of today, both ATMS and CrIS radiances are well calibrated and the SDR data have reached a validated level for user applications. This study will present the assimilation of ATMS and CrIS data in the Hurricane Weather Research and Forecast Model (HWRF) Gridpoint Statistical Interpolation (GSI) system and the impacts from uses of new satellite data on hurricane track and intensity forecasts in the Western Pacific. A new quality control (QC) approach is developed based on CrIS longwave and shortwave CO2 channels to detect the clouds at different altitudes. The double CO2 bands allow for retrieving the optically thin clouds due to their differential absorption and scattering properties. The cloud masks derived from CrIS double CO2 bands are compared with the current GSI baseline QC algorithm in different cloud regimes. Impacts of an improved QC on the prediction of hurricane and typhoon track and intensity are demonstrated with the 2014 Typhoon cases. Since November 2011, NOAA has begun generating the CrIS full resolution data. The improvements in the quality control from using CrIS full spectral resolution data are expected since an increase in CrIS shortwave channel resolution that is consistent with CrIS longwave resolution can lead to more and better matches in the weighting function heights of those paired CO2 bands and thus more detailed vertical structures of detected clouds. The potential impacts from the CrIS full spectral resolution QC on tropical cyclone forecasts are also assessed.

  20. Absolute radiometric calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

    1986-01-01

    Calibration data for the solar reflective bands of the Landsat-5 TM obtained from five in-flight absolute radiometric calibrations from July 1984-November 1985 at White Sands, New Mexico are presented and analyzed. Ground reflectance and atmospheric data were utilized to predict the spectral radiance at the entrance pupil of the TM and the average number of digital counts in each TM band. The calibration of each of the TM solar reflective bands was calculated in terms of average digital counts/unit spectral radiance for each band. It is observed that for the 12 reflectance-based measurements the rms variation from the means as a percentage of the mean is + or - 1.9 percent; for the 11 measurements in the IR bands, it is + or - 3.4 percent; and the rms variation for all 23 measurements is + or - 2.8 percent.

  1. Hyperspectral radiance simulator: cloudy radiance modeling and beyond

    NASA Astrophysics Data System (ADS)

    Huang, Hung-Lung; Tobin, David C.; Li, Jun; Olson, Erik R.; Baggett, Kevin; Huang, Bormin; Mecikalski, John; Knuteson, Robert O.; Osborne, Brian; Posselt, Derek; Antonelli, Paolo B.; Revercomb, Henry E.; Smith, William L.; Yang, Ping

    2003-04-01

    Current and future advanced atmospheric profile sounding and imaging instruments are evolving to enable global or hemispherical hyperspectral resolution measurements from space. The NASA/Navy/NOAA Geosynchronous Imaging FTS (GIFTS) for EO-3, NOAA Hyperspectral Environmental Sounder (HES) for GOES-R, and the currently operational Atmospheric Infrared Sounder (AIRS) on the NASA's Aqua Spacecraft will collect infrared high-spectral resolution/hyperspectral radiance spectra for remote sensing of the atmosphere, clouds, land, and ocean surfaces. These semi-continuous infrared high spectral- resolution/hyperspectral radiances will provide unprecedented information in the infrared region that is highly sensitive to absorption and emission of clouds. For sounding the atmospheric profiles one must perform cloud clearing or model the radiative effects of cloud explicitly if sounding is desired under cloud-contaminated conditions. We will describe the approach for modeling cloud attenuation in a fast-parameterized forward model that treats clouds as an additional absorber. Together with the usual clear forward model spectroscopic inputs, cloud altitude, effective particle size and shape and its ice or liquid water content are required input variables. Based on this efficient cloudy radiative transfer model, the simulation of the spatial and temporal coherent radiance images in three dimensions becomes possible. We will further explain how these 3-D GIFTS radiance cubes are used as test bed for a variety of trade studies.

  2. Validation of short-pulse-laser-based measurement setup for absolute spectral irradiance responsivity calibration.

    PubMed

    Schuster, Michaela; Nevas, Saulius; Sperling, Armin

    2014-05-01

    This paper describes the validation process of mode-locked lasers in the "tunable lasers in photometry" (TULIP) setup at Physikalisch-Technische Bundesanstalt (PTB) regarding spectral irradiance responsivity calibrations. Validation has been carried out in the visible spectral range, 400-700 nm, with two different photometer heads and in the long wavelength range, 690-780 nm, with a filtered radiometer. A comparison of the results against those from two different validated measurement setups has been carried out for validation. For the visible spectral range, the comparison is conducted against the data obtained from a lamp-based monochromator setup for spectral irradiance responsivity calibrations and against the photometric values (integral quantity) measured at the photometric bench setup of PTB. For the long wavelength range, comparisons against results from two different lamp-based monochromator measurement setups were made. Additionally, the effect of different radiation bandwidths on interference oscillations has been determined for a filter radiometer without a diffuser. A procedure for the determination of the optimum bandwidth of the setup for the respective measurement device is presented. PMID:24921865

  3. Absolute irradiance of the Moon for on-orbit calibration

    USGS Publications Warehouse

    Stone, T.C.; Kieffer, H.H.; ,

    2002-01-01

    The recognized need for on-orbit calibration of remote sensing imaging instruments drives the ROLO project effort to characterize the Moon for use as an absolute radiance source. For over 5 years the ground-based ROLO telescopes have acquired spatially-resolved lunar images in 23 VNIR (Moon diameter ???500 pixels) and 9 SWIR (???250 pixels) passbands at phase angles within ??90 degrees. A numerical model for lunar irradiance has been developed which fits hundreds of ROLO images in each band, corrected for atmospheric extinction and calibrated to absolute radiance, then integrated to irradiance. The band-coupled extinction algorithm uses absorption spectra of several gases and aerosols derived from MODTRAN to fit time-dependent component abundances to nightly observations of standard stars. The absolute radiance scale is based upon independent telescopic measurements of the star Vega. The fitting process yields uncertainties in lunar relative irradiance over small ranges of phase angle and the full range of lunar libration well under 0.5%. A larger source of uncertainty enters in the absolute solar spectral irradiance, especially in the SWIR, where solar models disagree by up to 6%. Results of ROLO model direct comparisons to spacecraft observations demonstrate the ability of the technique to track sensor responsivity drifts to sub-percent precision. Intercomparisons among instruments provide key insights into both calibration issues and the absolute scale for lunar irradiance.

  4. Usability of a Fourier transform spectroradiometer for absolute surface spectral solar UV irradiance measurements.

    PubMed

    Meindl, Peter; Wähmer, Martin; Monte, Christian

    2014-10-20

    The suitability of a commercially available Fourier transform spectrometer equipped with a fiber-coupled global entrance optic as a reference spectroradiometer for the measurement of spectral solar ultraviolet irradiance at ground level has been investigated. The instrument has been characterized with respect to the wavelength uncertainty, and a calibration of the spectral irradiance responsivity has been performed by using the calculable irradiance of a high temperature black-body radiator and by using a secondary irradiance standard lamp. The relative standard uncertainty of solar irradiance measurements in the wavelength range from 310 nm to 400 nm with this spectroradiometer, based on the described methodology, is 1.6% for solar zenith angles of less than 60°.

  5. Usability of a Fourier transform spectroradiometer for absolute surface spectral solar UV irradiance measurements.

    PubMed

    Meindl, Peter; Wähmer, Martin; Monte, Christian

    2014-10-20

    The suitability of a commercially available Fourier transform spectrometer equipped with a fiber-coupled global entrance optic as a reference spectroradiometer for the measurement of spectral solar ultraviolet irradiance at ground level has been investigated. The instrument has been characterized with respect to the wavelength uncertainty, and a calibration of the spectral irradiance responsivity has been performed by using the calculable irradiance of a high temperature black-body radiator and by using a secondary irradiance standard lamp. The relative standard uncertainty of solar irradiance measurements in the wavelength range from 310 nm to 400 nm with this spectroradiometer, based on the described methodology, is 1.6% for solar zenith angles of less than 60°. PMID:25401540

  6. In-flight absolute radiometric calibration of the thematic mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1983-01-01

    The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer.

  7. The NBS scale of radiance temperature

    NASA Technical Reports Server (NTRS)

    Waters, William R.; Walker, James H.; Hattenburg, Albert T.

    1988-01-01

    The measurement methods and instrumentation used in the realization and transfer of the International Practical Temperature Scale (IPTS-68) above the temperature of freezing gold are described. The determination of the ratios of spectral radiance of tungsten-strip lamps to a gold-point blackbody at a wavelength of 654.6 nm is detailed. The response linearity, spectral responsivity, scattering error, and polarization properties of the instrumentation are described. The analysis of the sources of error and estimates of uncertainty are presented. The assigned uncertainties (three standard deviations) in radiance temperature range from + or - 2 K at 2573 K to + or - 0.5 K at 1073 K.

  8. Absolute spectral characterization of silicon barrier diode: Application to soft X-ray fusion diagnostics at Tore Supra

    SciTech Connect

    Vezinet, D.; Mazon, D.; Malard, P.

    2013-07-14

    This paper presents an experimental protocol for absolute calibration of photo-detectors. Spectral characterization is achieved by a methodology that unlike the usual line emissions-based method, hinges on the Bremsstrahlung radiation of a Soft X-Ray (SXR) tube only. Although the proposed methodology can be applied virtually to any detector, the application presented in this paper is based on Tore Supra's SXR diagnostics, which uses Silicon Surface Barrier Diodes. The spectral response of these n-p junctions had previously been estimated on a purely empirical basis. This time, a series of second-order effects, like the spatial distribution of the source radiated power or multi-channel analyser non linearity, are taken into account to achieve accurate measurements. Consequently, a parameterised physical model is fitted to experimental results and the existence of an unexpected dead layer (at least 5 {mu}m thick) is evidenced. This contribution also echoes a more general on-going effort in favour of long-term quality of passive radiation measurements on Tokamaks.

  9. Absolute Rovibrational Intensities of C-12O2-16 Absorption Bands in the 3090-3850/ CM Spectral Region

    NASA Technical Reports Server (NTRS)

    Devi, V. Malathy; Benner, D. Chris; Rinsland, Curtis P.; Smith, Mary Ann H.

    1998-01-01

    A multispectrum nonlinear least-squares fitting technique has been used to determine the absolute intensities for approximately 1500 spectral lines in 36 vibration - rotation bands Of C-12O2-16 between 3090 and 3850/ cm. A total of six absorption spectra of a high- purity (99.995% minimum) natural sample of carbon dioxide were used in the analysis. The spectral data (0.01/cm resolution) were recorded at room temperature and low pressure (1 to 10 Torr) using the McMath-Pierce Fourier transform spectrometer of the National Solar Observatory (NSO) on Kitt Peak. The absorption path lengths for these spectra varied between 24.86 and 385.76 m. The first experimental determination of the intensity of the theoretically predicted 2(nu)(sub 2, sup 2) + nu(sub 3) "forbidden" band has been made. The measured line intensities obtained for each band have been analyzed to determine the vibrational band intensity, S(sub nu), in /cm/( molecule/sq cm) at 296 K, square of the rotationless transition dipole moment |R|(exp 2) in Debye, as well as the nonrigid rotor coefficients. The results are compared to the values listed in the 1996 HITRAN database which are obtained using the direct numerical diagonalization (DND) technique as well as to other published values where available.

  10. Modeling and Assimilating Ocean Color Radiances

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2012-01-01

    Radiances are the source of information from ocean color sensors to produce estimates of biological and geochemical constituents. They potentially provide information on various other aspects of global biological and chemical systems, and there is considerable work involved in deriving new information from these signals. Each derived product, however, contains errors that are derived from the application of the radiances, above and beyond the radiance errors. A global biogeochemical model with an explicit spectral radiative transfer model is used to investigate the potential of assimilating radiances. The results indicate gaps in our understanding of radiative processes in the oceans and their relationships with biogeochemical variables. Most important, detritus optical properties are not well characterized and produce important effects of the simulated radiances. Specifically, there does not appear to be a relationship between detrital biomass and its optical properties, as there is for chlorophyll. Approximations are necessary to get beyond this problem. In this reprt we will discuss the challenges in modeling and assimilation water-leaving radiances and the prospects for improving our understanding of biogeochemical process by utilizing these signals.

  11. Improved entrance optics design for ground-based solar spectral ultraviolet irradiance measurements and system absolute calibration

    NASA Astrophysics Data System (ADS)

    Dai, Caihong; Yu, Jialin; Huang, Bo; Tian, Yan

    2009-07-01

    The angular response of entrance optics is an important parameter for solar spectral UV measurements, and ideal cosine entrance optics is required to measure ground-based global solar spectral UV irradiance including direct and diffuse radiation over a solid angle of 2π sr. Early international comparisons have shown that deviations from the ideal cosine response lead to uncertainties in solar measurements of more than 10%. A special spectroradiometer used for solar spectral UV measurements was developed at National Institute of Metrology (NIM). Based on Polytetrafluoroethylene (PTFE) integrating sphere, seven kinds of cosine-entrance system were designed and compared. A special cosine measurement apparatus was developed to measure the angular response of the entrance optics. Experimental results show that, the integral cosine error is 1.41% for a novel combination entrance optics, which is composed by a PTFE integrating sphere, a spherical ground quartz diffuser and a special correction ring, and the cosine error is 0.08% for an incidence angle of θ=+/-30°, 0.84% at θ=+/-45°, -0.47% at θ=+/-60°, -0.74% at θ=+/-70°, and 5.47% at θ=+/-80°. With the new non-plane entrance optics, the angular response of the solar UV spectroradiometer is improved evidently, but on the other side, the system's absolute calibration becomes more difficult owing to the curved geometry of the new diffuser. The calibration source is a 1000W tungsten halogen lamp, but the measurement object is the global radiation of the solar, so a small error of the calibration distance will lead to an enormous measurement error of solar spectral UV irradiance. When the calibration distance is 500mm, for an actual diffuser with spherical radius 32.5mm and spherical height 20mm, the calibration error will be up to 3%~10% on the assumption that the starting point was calculated just from the acme or the bottom of the half-spherical diffuser. It was investigated that which point inside the

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Use of the ARM Measurement of Spectral Zenith Radiance For Better Understanding Of 3D Cloud-Radiation Processes and Aerosol-Cloud Interaction

    SciTech Connect

    Chiu, Jui-Yuan

    2010-10-19

    Our proposal focuses on cloud-radiation processes in a general 3D cloud situation, with particular emphasis on cloud optical depth and effective particle size. We also focus on zenith radiance measurements, both active and passive. The proposal has three main parts. Part One exploits the "solar-background" mode of ARM lidars to allow them to retrieve cloud optical depth not just for thin clouds but for all clouds. This also enables the study of aerosol cloud interactions with a single instrument. Part Two exploits the large number of new wavelengths offered by ARM's zenith-pointing ShortWave Spectrometer (SWS), especially during CLASIC, to develop better retrievals not only of cloud optical depth but also of cloud particle size. We also propose to take advantage of the SWS's 1 Hz sampling to study the "twilight zone" around clouds where strong aerosol-cloud interactions are taking place. Part Three involves continuing our cloud optical depth and cloud fraction retrieval research with ARM's 2NFOV instrument by, first, analyzing its data from the AMF-COPS/CLOWD deployment, and second, making our algorithms part of ARM's operational data processing.

  14. Measurement of zone plate efficiencies in the extreme ultraviolet and applications to radiation monitors for absolute spectral emission

    NASA Astrophysics Data System (ADS)

    Seely, John; Holland, Glenn; Bremer, James C.; Zukowski, Tim; Feser, Michael; Feng, Yan; Kjornrattanawanich, Benjawan; Goray, Leonid

    2006-08-01

    The diffraction efficiencies of a Fresnel zone plate (ZP), fabricated by Xradia Inc. using the electron-beam writing technique, were measured using polarized, monochromatic synchrotron radiation in the extreme ultraviolet wavelength range 3.4-22 nm. The ZP had 2 mm diameter, 3330 zones, 150 nm outer zone width, and a 1 mm central occulter. The ZP was supported by a 100 nm thick Si 3N 4 membrane. The diffraction patterns were recorded by CMOS imagers with phosphor coatings and with 5.2 μm or 48 μm pixels. The focused +n orders (n=1-4), the diverging -1 order, and the undiffracted 0 order were observed as functions of wavelength and off-axis tilt angle. Sub-pixel focusing of the +n orders was achieved. The measured efficiency in the +1 order was in the 5% to 30% range with the phase-shift enhanced efficiency occurring at 8.3 nm where the gold bars are partially transmitting. The +2 and higher order efficiencies were much lower than the +1 order efficiency. The efficiencies were constant when the zone plate was tilted by angles up to +/-1° from the incident radiation beam. This work indicates the feasibility and benefits of using zone plates to measure the absolute EUV spectral emissions from solar and laboratory sources: relatively high EUV efficiency in the focused +1 order, good out-of-band rejection resulting from the low higher-order efficiencies and the ZP focusing properties, insensitivity to (unfocused) visible light scattered by the ZP, flat response with off-axis angle, and insensitivity to the polarization of the radiation based on the ZP circular symmetry. EUV sensors with Fresnel zone plates potentially have many advantages over existing sensors intended to accurately measure absolute EUV emission levels, such as those implemented on the GOES N-P satellites that use transmission gratings which have off-axis sensitivity variations and poor out-of-band EUV and visible light rejection, and other solar and laboratory sensors using reflection gratings which

  15. SOLSPEC investigation on board the International Space Station: The Absolute Solar Spectral Irradiance in the Infrared Domain

    NASA Astrophysics Data System (ADS)

    Thuillier, Gérard; Harder, Jerry; Shapiro, Alexander; Woods, Thomas; Perrin, Jean-Marie; Snow, Marty; Sukhodolov, Timofei; Schmutz, Werner

    2015-04-01

    Onboard the SOLAR payload of the International Space Station (ISS), the SOLSPEC spectrometer measures the solar spectral irradiance (SSI) from 16 to 2900 nm. This instrument uses lamps to monitor its behavior in orbit. In particular, it employs two tungsten ribbon lamps in the IR domain (1000-2900 nm). Initially, the infrared absolute irradiance scale was determined from the preflight laboratory calibration coefficients and the in-flight measurements gathered at first light in April 2008. Subsequent publications suggest a systematic discrepancy between SOLAR-ISS measurements and the ATLAS 3 spectrum obtained from SOLSPEC observations onboard the shuttle-ATLAS missions with the discrepancy reaching 10 % at 1800 nm. We show that such a discrepancy has strong implications for the Total Solar Irradiance (TSI) and the brightness temperature of the lower solar photosphere. Furthermore, comparisons with independent spectra either obtained on ground and in space will be also shown and commented. The origin of the ATLAS 3 to SOLSPEC differences have been extensively analyzed; the onboard lamp and solar data time series indicates that the IR spectrometer did not reach a permanent regime until after several months of operation. The solar measurements at first light and in permanent regime show a difference, which provides an effective wavelength dependent correction factor for the first light spectrum. The SOLSPEC-ISS spectrum obtained in this permanent regime is consistent with the ATLAS 3 spectrum within their combined uncertainties and will be identified in the literature as SOLAR 2rev. We present analysis of this SOLAR 2rev spectrum in terms of its contribution to TSI, the lower photospheric temperature, and comparisons with independently measured IR spectra from ground-based and on-orbit platforms.

  16. Infrared cloud radiance.

    PubMed

    Kattawar, G W; Plass, G N

    1969-06-01

    The radiance of clouds is calculated at nine wavelengths in the ir. The single scattering function is obtained by Mie theory from the measured values of the complex index of refraction and with two different drop size distributions. Multiple scattering is taken into account by a Monte Carlo technique which computes the exact three-dimensional paths of the photons. The upward and downward radiance is obtained as a function of optical thickness, angle of observation, drop size distribution, and incident solar angle. The mean optical path of the photon, the cloud albedo, and the flux at the lower and upper boundaries are also given.

  17. Radiance Measurement for Low Density Mars Entry

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.

    2012-01-01

    We report measurements of radiance behind a shock wave in Martian simulant (96% CO2, 4% N2) atmosphere at conditions relevant for aerodynamic decelerators. Shock waves are generated in the NASA Ames Electric Arc Shock Tube (EAST) facility at velocities from 6-8 km/s and freestream densities from 1.2-5.9 x 10(exp -4) kilograms per cubic meter (0.05-0.25 Torr, corresponding to 35-50 km altitude). Absolute radiance is measured as a function of wavelength and position in the shock. Radiance measurements extend from the vacuum ultraviolet to near infrared (120-1650 nm). As at higher density/velocity, radiation is dominate by CO 4th positive radiation in the vacuum ultraviolet, though CN contribution is also significant. At most low density conditions, the shock does not relax to equilibrium over several centimeters. A small number of measurements in the mid-infrared were performed to quantify radiation from the fundamental vibrational transition in CO, and this is found to be a minor contributor to the overall radiance at these speeds. Efforts to extend test time and reliability in the 60 cm (24) shock tube will be discussed in the full paper.

  18. Solar radiance models for determination of ERBE scanner filter factor

    NASA Technical Reports Server (NTRS)

    Arduini, R. F.

    1985-01-01

    Shortwave spectral radiance models for use in the spectral correction algorithms for the ERBE Scanner Instrument are provided. The required data base was delivered to the ERBe Data Reduction Group in October 1984. It consisted of two sets of data files: (1) the spectral bidirectional angular models and (2) the spectral flux modes. The bidirectional models employ the angular characteristics of reflection by the Earth-atmosphere system and were derived from detailed radiance calculations using a finite difference model of the radiative transfer process. The spectral flux models were created through the use of a delta-Eddington model to economically simulate the effects of atmospheric variability. By combining these data sets, a wide range of radiances may be approximated for a number of scene types.

  19. Experimental and Metrological Basis for SI-Traceable Infrared Radiance Measurements From Space

    NASA Astrophysics Data System (ADS)

    Gero, P. J.; Dykema, J. A.; Anderson, J. G.; Leroy, S. S.

    2007-12-01

    In order to establish a climate benchmark record and to be useful in interdecadal climate forecast testing, satellite measurements of high spectral resolution infrared radiance must have uncertainty estimates that can be proven beyond a doubt. An uncertainty in radiance of about 1 part in 1000 is required for climate applications. This can be accomplished by appealing to the best measurement practices of the metrology community. The International System of Units (SI) are linked to fundamental physical properties of matter, and can be realized anywhere in the world without bias. By doing so, one can make an accurate observation to within a specified uncertainty. Achieving SI-traceable radiance measurements from space is a novel requirement, and requires specialized sensor design and a disciplined experimental approach. Infrared remote sensing satellite instruments typically employ blackbody calibration targets, which are tied to the SI through Planck's law and the definition of the Kelvin. The blackbody temperature and emissivity, however, must be determined accurately on- orbit, in order for the blackbody emission scale to be SI-traceable. We outline a methodology of instrument design, pre-flight calibration and on-orbit diagnostics for realizing SI- traceable infrared radiance measurements. This instrument is intended as a component of the Climate Absolute Radiance and Refractivity Earth Observatory (CLARREO), a high priority recommendation of the National Research Council decadal survey. Calibration blackbodies for remote sensing differ from a perfect Planckian blackbody; thus the component uncertainties must be evaluated in order to confer traceability. We have performed traceability experiments in the laboratory to verify blackbody temperature, emissivity and the end-to-end radiance scale. We discuss the design of the Harvard standard blackbody and an intercomparison campaign that will be conducted with the GIFTS blackbody (University of Wisconsin, Madison) and

  20. Snow Radiance Assimilation Studies

    NASA Astrophysics Data System (ADS)

    Kim, E. J.; Durand, M. T.; Toure, A.; Margulis, S. A.; Goita, K.; Royer, A.; Lu, H.

    2009-12-01

    Passive microwave-based retrievals of terrestrial snow parameters from satellite observations form a 30-year global record which will continue for the forseeable future. So far, these snow retrievals have been generated primarily by regression-based empirical “inversion” methods based on snapshots in time, and are limited to footprints around 25 km in diameter. Assimilation of microwave radiances into physical land surface models may be used to create a retrieval framework that is inherently self-consistent with respect to model physics as well as a more physically-based approach vs. legacy retrieval/inversion methods. This radiance assimilation approach has been used for years for atmospheric parameters by the operational weather forecasting community with great success, and represents one motivation for our work. A radiance assimilation scheme for snow requires a snowpack land surface model (LSM) coupled to a radiative transfer model (RTM). In previous local-scale studies, Durand, Kim, & Margulis (2008) explored the requirements on LSM model fidelity (i.e., snowpack state information) required in order for the RTM to produce brightness temperatures suitable for radiance assimilation purposes at a local scale, using the well-known Microwave Emission Model for Layered Snowpacks (MEMLS) as the RTM and a combination of Simple SIB (SSiB) and Snow Atmosphere (SAST) as the LSM. They also demonstrated improvement of simulated snow depth through the use of an ensemble Kalman filter scheme at this local scale (2009). This modeling framework reflects another motivation—namely, possibilities for downscaling. Our focus at this stage has been at the local scale where high-quality ground truth data is available in order to evaluate radiance assimilation under a “best case scenario.” The quantitative results then form a benchmark for future assessment of effects such as sparse forcing data, upscaling/downscaling, forest attenuation, and model details. Field data from

  1. Absolute Radiometric Calibration of KOMPSAT-3A

    NASA Astrophysics Data System (ADS)

    Ahn, H. Y.; Shin, D. Y.; Kim, J. S.; Seo, D. C.; Choi, C. U.

    2016-06-01

    This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3A (KOMPSAT-3A) performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG) in 2015.The primary stages of this study are summarized as follows: (1) A field campaign to determine radiometric calibrated target fields was undertaken in Mongolia and South Korea. Surface reflectance data obtained in the campaign were input to a radiative transfer code that predicted at-sensor radiance. Through this process, equations and parameters were derived for the KOMPSAT-3A sensor to enable the conversion of calibrated DN to physical units, such as at-sensor radiance or TOA reflectance. (2) To validate the absolute calibration coefficients for the KOMPSAT-3A sensor, we performed a radiometric validation with a comparison of KOMPSAT-3A and Landsat-8 TOA reflectance using one of the six PICS (Libya 4). Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3A sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. The average difference in TOA reflectance between KOMPSAT-3A and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB) region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3A was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3Aensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. Toovercome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor.

  2. Temporal radiance caching.

    PubMed

    Gautron, Pascal; Bouatouch, Kadi; Pattanaik, Sumanta

    2007-01-01

    We present a novel method for fast, high quality computation of glossy global illumination in animated environments. Building on the irradiance caching and radiance caching algorithms, our method leverages temporal coherence by sparse temporal sampling and interpolation of the indirect lighting. In our approach, part of the global illumination solution computed in previous frames is reused in the current frame. Our reusing scheme adapts to the change of incoming radiance by updating the indirect lighting only where there is a significant change. By reusing data in several frames, our method removes the flickering artifacts and yields a significant speedup compared to classical computation in which a new cache is computed for every frame. We also define temporal gradients for smooth temporal interpolation. A key aspect of our method is the absence of any additional complex data structure, making the implementation into any existing renderer based on irradiance and radiance caching straightforward. We describe the implementation of our method using graphics hardware for improved performance.

  3. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Subhash, Hrebesh M.; Choudhury, Niloy; Jacques, Steven L.; Wang, Ruikang K.; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.

    2012-01-01

    Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from each of the delay-encoded vibration images with a noise floor of ~0.3nm at 200Hz.

  4. Absolute Radiometric Calibration of Narrow-Swath Imaging Sensors with Reference to Non-Coincident Wide-Swath Sensors

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Thome, Kurtis; Lockwood, Ronald

    2012-01-01

    An inter-calibration method is developed to provide absolute radiometric calibration of narrow-swath imaging sensors with reference to non-coincident wide-swath sensors. The method predicts at-sensor radiance using non-coincident imagery from the reference sensor and knowledge of spectral reflectance of the test site. The imagery of the reference sensor is restricted to acquisitions that provide similar view and solar illumination geometry to reduce uncertainties due to directional reflectance effects. Spectral reflectance of the test site is found with a simple iterative radiative transfer method using radiance values of a well-understood wide-swath sensor and spectral shape information based on historical ground-based measurements. At-sensor radiance is calculated for the narrow-swath sensor using this spectral reflectance and atmospheric parameters that are also based on historical in situ measurements. Results of the inter-calibration method show agreement on the 2 5 percent level in most spectral regions with the vicarious calibration technique relying on coincident ground-based measurements referred to as the reflectance-based approach. While the variability of the inter-calibration method based on non-coincident image pairs is significantly larger, results are consistent with techniques relying on in situ measurements. The method is also insensitive to spectral differences between the sensors by transferring to surface spectral reflectance prior to prediction of at-sensor radiance. The utility of this inter-calibration method is made clear by its flexibility to utilize image pairings with acquisition dates differing in excess of 30 days allowing frequent absolute calibration comparisons between wide- and narrow-swath sensors.

  5. Atmospheric Emitted Radiance Interferometer (AERI) Handbook

    DOE Data Explorer

    Gero, Jonathan; Hackel, Denny; Garcia, Raymond

    2005-01-01

    The atmospheric emitted radiance interferometer (AERI) is a ground-based instrument that measures the downwelling infrared radiance from the Earth’s atmosphere. The observations have broad spectral content and sufficient spectral resolution to discriminate among gaseous emitters (e.g., carbon dioxide and water vapor) and suspended matter (e.g., aerosols, water droplets, and ice crystals). These upward-looking surface observations can be used to obtain vertical profiles of tropospheric temperature and water vapor, as well as measurements of trace gases (e.g., ozone, carbon monoxide, and methane) and downwelling infrared spectral signatures of clouds and aerosols.The AERI is a passive remote sounding instrument, employing a Fourier transform spectrometer operating in the spectral range 3.3–19.2 μm (520–3020 cm-1) at an unapodized resolution of 0.5 cm-1 (max optical path difference of 1 cm). The extended-range AERI (ER-AERI) deployed in dry climates, like in Alaska, have a spectral range of 3.3–25.0 μm (400–3020 cm-1) that allow measurements in the far-infrared region. Typically, the AERI averages views of the sky over a 16-second interval and operates continuously.

  6. Service Oriented Gridded Atmospheric Radiances (SOAR)

    NASA Astrophysics Data System (ADS)

    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

  7. Automatic gonio-spectrophotometer for the absolute measurement of the spectral BRDF at in- and out-of-plane and retroreflection geometries

    NASA Astrophysics Data System (ADS)

    Rabal, A. M.; Ferrero, A.; Campos, J.; Fontecha, J. L.; Pons, A.; Rubiño, A. M.; Corróns, A.

    2012-06-01

    This paper presents the description and the characterization of the gonio-spectrophotometer GEFE (the acronym for 'Gonio-EspectroFotómetro Español'). This device has been designed and built for the low-uncertainty absolute measurement of the bidirectional reflectance distribution function (BRDF). It comprises a fixed, collimated and uniform light source, a six-axis robot-arm to rotate the sample and a spectroradiometer that may revolve around the sample to be able to vary the source-to-detector angular separation. This gonio-spectrophotometer makes it possible to perform spectral measurements in the visible range, both inside and outside the incidence plane, as well as measurements in retroreflection conditions. This fully automated system is able to measure autonomously a sample's complete spectral BRDF (comprising around 1000 different angular configurations) in less than 4 h.

  8. First-principles calculation of spectral features, chemical shift and absolute threshold of ELNES and XANES using a plane wave pseudopotential method

    NASA Astrophysics Data System (ADS)

    Mizoguchi, Teruyasu; Tanaka, Isao; Gao, Shang-Peng; Pickard, Chris J.

    2009-03-01

    Spectral features, chemical shifts, and absolute thresholds of electron energy loss near-edge structure (ELNES) and x-ray absorption near-edge structure (XANES) for selected compounds, i.e. TiO2 (rutile), TiO2 (anatase), SrTiO3, Ti2O3, Al2O3, AlN and β-Ga2O3, were calculated by a plane wave pseudopotential method. Experimental ELNES/XANES of those compounds were well reproduced when an excited pseudopotential, which includes a core hole, was used. In addition to the spectral features, it was found that chemical shifts among different compounds were also reproduced by correcting the contribution of the excited pseudopotentials to the energy of the core orbital.

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

    SciTech Connect

    La Lone, B. M. Stevens, G. D.; Turley, W. D.; Holtkamp, D. B.; Iverson, A. J.; Hixson, R. S.; Veeser, L. R.

    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.

  10. Release Path Temperatures of Shock-Compressed Tin from Dynamic Reflectance and Radiance Measurements

    SciTech Connect

    La Lone, B. M.; Stevens, G. D.; Turley, W. D.; Holtkamp, D. B.; Iverson, A. J.; Hixson, R. S.; Veeser, L. R.

    2013-08-01

    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/R0 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.

  11. Sea-based Infrared Radiance Measurements of Ocean and Atmosphere from the ACAPEX/CalWater2 Campaign

    NASA Astrophysics Data System (ADS)

    Gero, P. J.; Knuteson, R.; Hackel, D.; Phillips, C.; Westphall, M.

    2015-12-01

    The ARM Cloud Aerosol Precipitation Experiment (ACAPEX) / CalWater2 was a joint DOE/NOAA field campaign in early 2015 to study atmospheric rivers in the Pacific Ocean and their impacts on the western United States. The campaign goals were to improve understanding and modeling of large-scale dynamics and cloud and precipitation processes associated with atmospheric rivers and aerosol-cloud interactions that influence precipitation variability and extremes in the western United States. Coordinated measurements were made from ground-, aircraft- and sea-based platforms. The second ARM mobile facility (AMF-2) was deployed on board the NOAA Ship Ronald H. Brown for this campaign, which included a new Marine Atmospheric Emitted Radiance Interferometer (M-AERI) to measure the atmospheric downwelling and reflected infrared radiance spectrum at the Earth's surface with high absolute accuracy. The M-AERI measures spectral infrared radiance between 520-3020 cm-1 (3.3-19 μm) at a resolution of 0.5 cm-1. The M-AERI can selectively view the atmospheric scene at zenith, and ocean/atmospheric scenes over a range of ±45° from the horizon. The AERI uses two high-emissivity blackbodies for radiometric calibration, which in conjunction with the instrument design and a suite of rigorous laboratory diagnostics, ensures the radiometric accuracy to be better than 1% (3σ) of the ambient radiance. The M-AERI radiance spectra can be used to retrieve profiles of temperature and water vapor in the troposphere, as well as measurements of trace gases, cloud properties, surface emissivity and ocean skin temperature. We present preliminary results on measurements of ocean skin temperature, ocean emissivity properties as a function of view angle and wind speed, as well as comparisons with radiosondes and satellite observations.

  12. Directional radiance measurements: Challenges in the sampling of landscapes

    NASA Technical Reports Server (NTRS)

    Deering, D. W.

    1994-01-01

    Most earth surfaces, particularly those supporting natural vegetation ecosystems, constitute structurally and spectrally complex surfaces that are distinctly non-Lambertian reflectors. Obtaining meaningful measurements of the directional radiances of landscapes and obtaining estimates of the complete bidirectional reflectance distribution functions of ground targets with complex and variable landscape and radiometric features are challenging tasks. Reasons for the increased interest in directional radiance measurements are presented, and the issues that must be addressed when trying to acquire directional radiances for vegetated land surfaces from different types of remote sensing platforms are discussed. Priority research emphases are suggested, concerning field measurements of directional surface radiances and reflectances for future research. Primarily, emphasis must be given to the acquisition of more complete and directly associated radiometric and biometric parameter data sets that will empower the exploitation of the 'angular dimension' in remote sensing of vegetation through enabling the further development and rigorous validation of state of the art plant canopy models.

  13. Radiance-ratio algorithm wavelengths for remote oceanic chlorophyll determination

    NASA Technical Reports Server (NTRS)

    Hoge, Frank E.; Wright, C. Wayne; Swift, Robert N.

    1987-01-01

    Two-band radiance-ratio in-water algorithms in the visible spectrum have been evaluated for remote oceanic chlorophyll determination. Airborne active-passive (laser-solar) data from coastal, shelf-slope, and blue-water regions were used to generate two-dimensional chlorophyll-fluorescence and radiance-ratio statistical correlation matrices containing all possible two-band ratio combinations from the thirty-two available contiguous 11.25-nm passive bands. The principal finding was that closely spaced radiance-ratio bands yield chlorophyll estimates which are highly correlated with laser-induced chlorophyll fluorescence within several distinct regions of the ocean color spectrum. Band combinations in the yellow, orange-red, spectral regions showed considerable promise for satisfactory chlorophyll pigment estimation in near-coastal Case II waters. Pigment recovery in Case I waters was best accomplished using blue-green radiance ratios in the 490/500-nm region.

  14. A reference radiance-meter system for thermodynamic temperature measurements

    NASA Astrophysics Data System (ADS)

    Salim, S. G. R.; Briaudeau, S.; Bourson, F.; Rougié, B.; Truong, D.; Kozlova, O.; Coutin, J.-M.; Sadli, M.

    2016-06-01

    This paper presents the work carried out to evaluate the radiometric performance of a radiance-meter system which has been built at the LNE-Cnam to determine the thermodynamic temperature of high-temperature fixed points. The work comes as an integral part of the ‘implementing the new Kelvin’ (INK) project in which nine National Metrology Institutes (NMIs) strive to assign the thermodynamic temperatures to the melting curve of high-temperature fixed points with the lowest possible uncertainty. The method used in this research is based on the radiance approach. It exploits a system based on a laser-illuminated integrating sphere source whose radiance is absolutely measured by a trap detector through a well-defined geometry. The trap detector is calibrated traceable to the LNE-Cnam’s cryogenic radiometer. Once the radiance of the sphere is defined, a single grating-based spectroradiometer is used to measure the radiance of the fixed point source at the laser wavelength through direct comparison with the sphere radiance. This allows the thermodynamic temperature of the fixed point to be determined using Planck’s radiation law. The work provides a thorough evaluation of the system along with a detailed study of all related systematic effects and their corresponding uncertainties.

  15. In-flight Absolute Radiometric Calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, D.; Savage, R. K.

    1984-01-01

    The Thematic Mapper (TM) multispectral scanner system was placed into Earth orbit on July 16, 1982, as part of NASA's LANDSAT 4 payload. To determine temporal changes of the absolute radiometric calibration of the entire system in flight, spectroradiometric measurements of the ground and the atmosphere are made simultaneously with TM image acquisitions over the White Sands, New Mexico area. By entering the measured values into an atmospheric radiative transfer program, the radiance levels at the entrance pupil of the TM in four of the TM spectral bands are determined. These levels are compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors. By reference to an adjacent, larger uniform area, the calibration is extended to all 16 detectors in each of the three bands.

  16. In-flight absolute radiometric calibration of the thematic mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1984-01-01

    In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, New Mexico area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1:0.45 to 0.52 micrometers, band 2:0.53 to 0.61 micrometers band 3:0.62 to 0.70 micrometers and 4:0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors.

  17. In-flight absolute radiometric calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1984-01-01

    In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, NM area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1: 0.45 to 0.52 micrometers, band 2: 0.53 to 0.61 micrometers, band 3: 0.62 to 0.70 micrometers, and 4: 0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors. Previously announced in STAR as N84-15633

  18. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

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

    PubMed Central

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

    2016-01-01

    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. PMID:27478293

  20. MODIS Radiances for Earth System Science Studies

    NASA Astrophysics Data System (ADS)

    Ahmad, S. P.; Salomonson, V. V.; Barnes, W. L.; Xiong, X.; Leptoukh, G. G.; Serafino, G. N.

    2002-05-01

    MODIS, a major NASA's Earth Observing System (EOS) instrument, was launched aboard the Terra satellite on December 18, 1999 (10:30 am equator crossing time) for global monitoring of the atmosphere, the terrestrial ecosystems and oceans, to develop better understanding of the 'Total Earth System', and to study the effects of natural and human-induced changes on the global environment. MODIS with its 2330 km viewing swath width provides almost daily global coverage. It acquires data in 36 high spectral resolution bands between 0.415 and 14.235 micron with spatial resolutions of 250 m (2 bands), 500 m (5 bands), and 1000 m (29 bands). This year a similar instrument will be flown on the EOS-Aqua satellite (1:30 pm equator crossing time). This will enable us to study diurnal variation of the rapidly varying systems. The radiance data measured by MODIS at high spatial resolution with some new channels (never used before for remote sensing from space) provides improved and valuable information about the physical structure of the Earth system, such as vertical distribution of temperature and humidity, cloud and aerosol characteristics, sources and sinks of trace gases, surface emissivity, land and sea surface temperature, land cover and primary productivity, snow cover and sea ice concentration, glacier and polar ice sheets, ocean currents, ocean color, and phytoplankton. Almost all key climate and environmental parameters are available as standard MODIS products and are derived from MODIS high spatial resolution radiances. However, these radiometrically corrected and geolocated high spatial resolution radiance data (referred as Level 1B product) are much in demand by the science user community. These radiances are needed to enhance existing algorithms, to test new algorithms for the retrieval of existing or new parameters, and for developing simulation datasets for characterization of new sensors. MODIS radiance counts, calibrated radiance/reflectance, geolocation

  1. The Pathfinder Mission for Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Baize, R. R.; Boyer, C.; Cageao, R.; Currey, C.; Fleming, G. A.; Jackson, T.; Johnson, D. G.; Leckey, J.; Liu, X.; Lukashin, C.; McCorkel, J.; Mlynczak, M. G.; Shea, Y.; Thome, K. J.; Wielicki, B. A.; Sun, W.

    2016-01-01

    Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.

  2. Asteroid 951 Gaspra Near Infrared Mapping Spectrometer Radiance Data

    NASA Astrophysics Data System (ADS)

    Granahan, J. C., Jr.

    2015-12-01

    Five radiance spectra of asteroid 951 Gaspra have been archived in the Small Bodies Node of the NASA Planetary Data System [Granahan, 2014]. The radiance spectra were created from uncalibrated Galileo spacecraft Near Infrared Mapping Spectrometer files archived in the Imaging Node of the NASA Planetary Data System. The NASA Galileo spacecraft observed asteroid 951 Gaspra on October 29, 1991 with the Near Infrared Mapping Spectrometer (NIMS) at wavelengths ranging from 0.7 - 5.2 micrometers [Carlson et al., 1992]. The five radiance spectra consist of two 17, two 100, and one 329 spectral channel data sets. They record data that was acquired by NIMS at ranges between 27232.6 to 14723.8 kilometers from asteroid 951 Gaspra. The uncalibrated NIMS data were converted into radiance spectra using calibration coefficients obtained during the Galileo mission's first Earth encounter on December 8, 1990. The archived radiance spectral data is located at the URL (Universal Record Locator): http://sbn.psi.edu/pds/resource/gaspraspec.html and contains radiance, solar, incidence over flux, and data documentation. This archived data set contains a variety of spectral signatures. These signatures include absorptions near 1.0, 2.0, 2.8, 3.4, and 4.5 micrometers. The 1.0 and 2.0 micrometer features are indicators of olivine and pyroxene on the asteroid surface. The 2.8 micrometer feature has a shape similar to the combined spectra of multiple iron bearing phyllosilicates. The 3.4 micrometer feature is in the same location as absorptions created by a carbon-hydrogen bond. The 4.5 micrometer feature, present only in the 329 channel data set, corresponds in position to absorptions detected in sulfate minerals. Carlson, R. W., et al. (1992) Bull. of the A.A.S., 24, 932. Granahan, J. C. (2014), GO-A-NIMS-3-GASPRASPEC-V1.0, NASA Planetary Data System.

  3. Cross-calibration of Imaging Sensors using Model-based, SI-traceable Predictions of At-sensor Radiance

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel

    2012-01-01

    Many inter-consistency efforts force empirical agreement between sensors viewing a source nearly coincident in time and geometry that ensures consistency between sensors rather than obtain an SI-traceable calibration with documented error budgets. The method described here provides interconsistency via absolute radiometric calibration with defensible error budget avoiding systematic errors through prediction of at-sensor radiance for a site viewed by multiple sensors but not necessarily viewed at coincident times. The method predicts spectral radiance over a given surface site for arbitrary view and illumination angles and for any date dominated by clear-sky conditions. The foundation is a model-based, SI-traceable prediction of at-sensor radiance over selected sites based on physical understanding of the surface and atmosphere. The calibration of the ground site will include spatial, spectral, and sunview geometric effects based on satellite and ground-based data. The result is an interconsistency of hyperspectral and multispectral sensors spanning spatial resolutions from meters to kilometers all relative to the surface site rather than a single sensor. The source-centric philosophy of calibrating the site inherently accounts for footprint size mismatch, spectral band mismatch, and temporal and spatial sampling effects. The method for characterizing the test site allows its use for SI-traceable calibration of any sensor that can view the calibrated test site. Interconsistency is obtained through the traceability and error budget rather than coincident views. Such an approach to inter-consistency provides better understanding of biases between sensors as well producing more accurate results with documented SI-traceability that reduces the need for overlapping data sets.

  4. Advances in simulating radiance signatures for dynamic air/water interfaces

    NASA Astrophysics Data System (ADS)

    Goodenough, Adam A.; Brown, Scott D.; Gerace, Aaron

    2015-05-01

    The air-water interface poses a number of problems for both collecting and simulating imagery. At the surface, the magnitude of observed radiance can change by multiple orders of magnitude at high spatiotemporal frequency due to glinting effects. In the volume, similarly high frequency focusing of photons by a dynamic wave surface significantly changes the reflected radiance of in-water objects and the scattered return of the volume itself. These phenomena are often manifest as saturated pixels and artifacts in collected imagery (often enhanced by time delays between neighboring pixels or interpolation between adjacent filters) and as noise and greater required computation times in simulated imagery. This paper describes recent advances made to the Digital Image and Remote Sensing Image Generation (DIRSIG) model to address the simulation issues to better facilitate an understanding of a multi/hyper-spectral collection. Glint effects are simulated using a dynamic height field that can be driven by wave frequency models and generates a sea state at arbitrary time scales. The volume scattering problem is handled by coupling the geometry representing the surface (facetization by the height field) with the single scattering contribution at any point in the water. The problem is constrained somewhat by assuming that contributions come from a Snell's window above the scattering point and by assuming a direct source (sun). Diffuse single scattered and multiple scattered energy contributions are handled by Monte Carlo techniques employed previously. The model is compared to existing radiative transfer codes where possible, with the objective of providing a robust movel of time-dependent absolute radiance at many wavelengths.

  5. Final Scientific/Technical Report Grant title: Use of ARM Measurements of Spectral Zenith Radiance for Better Understanding of 3D Cloud-Radiation Processes and Aerosol-Cloud Interaction This is a collaborative project with the NASA GSFC project of Dr. A. Marshak and W. Wiscombe (PIs). This report covers BU activities from February 2011 to June 2011 and BU "no-cost extension" activities from June 2011 to June 2012. This report summarizes results that complement a final technical report submitted by the PIs in 2011.

    SciTech Connect

    Knyazikhin, Y

    2012-09-10

    Main results are summarized for work in these areas: spectrally-invariant approximation within atmospheric radiative transfer; spectral invariance of single scattering albedo for water droplets and ice crystals at weakly absorbing wavelengths; seasonal changes in leaf area of Amazon forests from leaf flushing and abscission; and Cloud droplet size and liquid water path retrievals from zenith radiance measurements.

  6. Camera response prediction for various capture settings using the spectral sensitivity and crosstalk model.

    PubMed

    Qiu, Jueqin; Xu, Haisong

    2016-09-01

    In this paper, a camera response formation model is proposed to accurately predict the responses of images captured under various exposure settings. Differing from earlier works that estimated the camera relative spectral sensitivity, our model constructs the physical spectral sensitivity curves and device-dependent parameters that convert the absolute spectral radiances of target surfaces to the camera readout responses. With this model, the camera responses to miscellaneous combinations of surfaces and illuminants could be accurately predicted. Thus, creating an "imaging simulator" by using the colorimetric and photometric research based on the cameras would be of great convenience. PMID:27607275

  7. Camera response prediction for various capture settings using the spectral sensitivity and crosstalk model.

    PubMed

    Qiu, Jueqin; Xu, Haisong

    2016-09-01

    In this paper, a camera response formation model is proposed to accurately predict the responses of images captured under various exposure settings. Differing from earlier works that estimated the camera relative spectral sensitivity, our model constructs the physical spectral sensitivity curves and device-dependent parameters that convert the absolute spectral radiances of target surfaces to the camera readout responses. With this model, the camera responses to miscellaneous combinations of surfaces and illuminants could be accurately predicted. Thus, creating an "imaging simulator" by using the colorimetric and photometric research based on the cameras would be of great convenience.

  8. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    SciTech Connect

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-11

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k= 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k= 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  9. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    NASA Astrophysics Data System (ADS)

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-01

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k = 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k = 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  10. Achieving Climate Change Absolute Accuracy in Orbit

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  11. Atmospheric radiance profile codes. Technical report

    SciTech Connect

    Yap, B.K.

    1986-09-17

    This report presents and describes the computer codes developed to generate atmospheric radiance profiles for various molecules, species, and rotational bands. Researchers extracted radiance profiles from the standard NLTE program output files and transferred them from the Cyber system to the Apollo system. Efforts include a routine to plot the radiance profiles sum total and SPIRE program measured data.

  12. Physical Retrieval of Surface Emissivity Spectrum from Hyperspectral Infrared Radiances

    NASA Technical Reports Server (NTRS)

    Li, Jun; Weisz, Elisabeth; Zhou, Daniel K.

    2007-01-01

    Retrieval of temperature, moisture profiles and surface skin temperature from hyperspectral infrared (IR) radiances requires spectral information about the surface emissivity. Using constant or inaccurate surface emissivities typically results in large retrieval errors, particularly over semi-arid or arid areas where the variation in emissivity spectrum is large both spectrally and spatially. In this study, a physically based algorithm has been developed to retrieve a hyperspectral IR emissivity spectrum simultaneously with the temperature and moisture profiles, as well as the surface skin temperature. To make the solution stable and efficient, the hyperspectral emissivity spectrum is represented by eigenvectors, derived from the laboratory measured hyperspectral emissivity database, in the retrieval process. Experience with AIRS (Atmospheric InfraRed Sounder) radiances shows that a simultaneous retrieval of the emissivity spectrum and the sounding improves the surface skin temperature as well as temperature and moisture profiles, particularly in the near surface layer.

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

    PubMed

    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

  14. Super-radiance in the sodium resonance lines from sodium iodide arc lamps

    SciTech Connect

    Karabourniotis, D.; Drakakis, E.

    2010-08-09

    Super-radiance observed within the centers of the sodium resonance D lines emitted by arc lamps containing sodium iodide as additive in a high-pressure mercury plasma environment was studied by high-resolution emission spectroscopy. The spectral radiance of these self-reversed lines including super-radiance was simulated by considering a local enhancement of the source function due to the presence of an additional source of radiation near the arc wall. Causes of this hitherto unrecognized source of radiation are given.

  15. Monochromator-Based Absolute Calibration of a Standard Radiation Thermometer

    NASA Astrophysics Data System (ADS)

    Mantilla, J. M.; Hernanz, M. L.; Campos, J.; Martín, M. J.; Pons, A.; del Campo, D.

    2014-04-01

    Centro Español de Metrología (CEM) is disseminating the International Temperature Scale (ITS-90), at high temperatures, by using the fixed points of Ag and Cu and a standard radiation thermometer. However, the future mise-en-pratique for the definition of the kelvin ( MeP-K) will include the dissemination of the kelvin by primary methods and by indirect approximations capable of exceptionally low uncertainties or increased reliability. Primary radiometry is, at present, able to achieve uncertainties competitive with the ITS-90 above the silver point with one of the possible techniques the calibration for radiance responsivity of an imaging radiometer (radiance method). In order to carry out this calibration, IO-CSIC (Spanish Designated Institute for luminous intensity and luminous flux) has collaborated with CEM, allowing traceability to its cryogenic radiometer. A monochromator integrating sphere-based spectral comparator facility has been used to calibrate one of the CEM standard radiation thermometers. The absolute calibrated standard radiation thermometer has been used to determine the temperatures of the fixed points of Cu, Co-C, Pt-C, and Re-C. The results obtained are 1357.80 K, 1597.10 K, 2011.66 K, and 2747.64 K, respectively, with uncertainties ranging from 0.4 K to 1.1 K.

  16. Principal component and sensitivity analysis of cirrus clouds using high-resolution IR radiance spectra: simulations and observations

    NASA Technical Reports Server (NTRS)

    Eldering, A.; Braverman, A.; Fetzer, E. J.

    2003-01-01

    A set of simulated and observed nadir-oriented high-resolution infrared emission spectra of synthetic cirrus clouds is analyzed to assess the spectrally dependent variability of radiance from the adjustment of some microphysical and bulk cirrus cloud properties.

  17. The Global Distribution of Limb Radiance Measured by the Midcourse Space Experiment (MSX)

    NASA Astrophysics Data System (ADS)

    Kendra, M. J.; Griffin, J. M.; O'Neil, R. R.; Gibson, J. J.

    2002-12-01

    The MSX SPIRIT III radiometer recorded infrared limb radiance simultaneously in five spectral bands in which the dominant signatures were due to 4.3 and 15 micron CO2, 9.6 micron O3 and 18 - 25 micron rotational water vapor emissions. In a vertical alignment, the detector columns covered a tangent altitude range of 60 km with 300 x 300 m resolution. The measurements were made in 153 episodic data collection events in the period from May 1996 to February 1997 over tangent heights from 25 to 150 km. They were recorded at all latitudes from a high inclination orbit and were made primarily in the eastern and northern hemispheres. Global radiance databases were constructed for each radiometer band by combining all valid detector values into one-second time and one km tangent altitude bins. Each database contains nearly 1e7 mean radiance values, indexed by latitude, longitude, altitude, date, solar illumination, and geomagnetic index. Radiance measurements from this database were binned in a variety of ways: latitude and longitude; latitude and month; latitude and local time; geomagnetic latitude and geomagnetic time; altitude and latitude; altitude and solar zenith angle; and altitude and month. Bin parameters were adjusted to achieve adequate coverage for determining population statistics within the distribution space. Global maps, seasonal summaries, and multi-dimensional plots of mean radiance, standard deviation of mean radiance, their ratio, minimum radiance, and maximum radiance will be presented. Special emphasis will be given to the 4.22-4.36 and 4.24-4.45 micron carbon dioxide bands and the 6.8-10.8 micron ozone band. Extreme values of limb radiance will be identified for each of the five spectral bands.

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

    NASA Technical Reports Server (NTRS)

    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.

  19. ScaRaB: first results of absolute and cross calibration

    NASA Astrophysics Data System (ADS)

    Trémas, Thierry L.; Aznay, Ouahid; Chomette, Olivier

    2015-10-01

    ScaRaB (SCAnner for RAdiation Budget) is the name of three radiometers whose two first flight models have been launched in 1994 and 1997. The instruments were mounted on-board Russian satellites, METEOR and RESURS. On October 12th 2011, a last model has been launched from the Indian site of Sriharikota. ScaRaB is a passenger of MEGHA-TROPIQUES, an Indo-French joint Satellite Mission for studying the water cycle and energy exchanges in the tropics. ScaRaB is composed of four parallel and independent channels. Channel-2 and channel-3 are considered as the main ones. Channel-1 is dedicated to measure solar radiance (0.5 to 0.7 μm) while channel-4 (10 to 13 μm) is an infrared window. The absolute calibration of ScaRab is assured by internal calibration sources (black bodies and a lamp for channel-1). However, during the commissioning phase, the lamp used for the absolute calibration of channel-1 revealed to be inaccurate. We propose here an alternative calibration method based on terrestrial targets. Due to the spectral range of channel-1, only calibration over desert sites (temporal monitoring) and clouds (cross band) is suitable. Desert sites have been widely used for sensor calibration since they have a stable spectral response over time. Because of their high reflectances, the atmospheric effect on the upward radiance is relatively minimal. In addition, they are spatially uniform. Their temporal instability without atmospheric correction has been determined to be less than 1-2% over a year. Very-high-altitude (10 km) bright clouds are good validation targets in the visible and near-infrared spectra because of their high spectrally consistent reflectance. If the clouds are very high, there is no need to correct aerosol scattering and water vapor absorption as both aerosol and water vapor are distributed near the surface. Only Rayleigh scattering and ozone absorption need to be considered. This method has been found to give a 4% uncertainty. Radiometric cross

  20. Tree canopy radiance measurement system

    NASA Technical Reports Server (NTRS)

    Caldwell, William; Vanderbilt, V. C.

    1989-01-01

    A system is described for obtaining both an estimate of the spatial mean bidirectional reflectance factor (BRF) for a tree canopy (displaying a horizontally heterogeneous foliage distribution) and the statistical significance of that estimate. The system includes a manlift supporting a horizontal beam 7 m long on which are mounted four radiometers. These radiometers may be pointed, and radiance data acquired, in any of 11 view directions in the principal plane of the sun. A total of 80 data points, acquired in 3 min, were used to estimate the BRF of a walnut orchard 5 m tall and detect true differences of 12 percent of the mean approximately 90 percent of the time.

  1. Uncertainty propagation algorithm from the radiometric calibration to the restored earth observation radiance.

    PubMed

    Guorui, Jia; Huijie, Zhao; Hao, Lei

    2014-04-21

    The uncertainty of the radiometric calibration affects the accuracy of the earth observation (EO) radiance restored from the remote sensing digital number (DN) data. However, it has not been intensively analyzed whether they are equivalent to each other. The algorithm to deduce the uncertainty of the restored EO radiance in the solar-reflective spectral range (400-2500 nm) along the uncertainty propagation chain in the radiometric calibration process is proposed. It was validated compared with the traditional calibration uncertainty algorithm through an example of calibrating an imaging spectrometer. The interval about the real EO radiance and the corresponding level of confidence was reported as a result, which shows the possibility to accurately expressing the quality of the restored EO radiance following the rules used in the field of metrology.

  2. Modeling the Radiance of the Moon for On-orbit Calibration

    USGS Publications Warehouse

    Stone, T.C.; Kieffer, H.H.; Becker, K.J.; ,

    2003-01-01

    The RObotic Lunar Observatory (ROLO) project has developed radiometric models of the Moon for disk-integrated irradiance and spatially resolved radiance. Although the brightness of the Moon varies spatially and with complex dependencies upon illumination and viewing geometry, the surface photometric properties are extremely stable, and therefore potentially knowable to high accuracy. The ROLO project has acquired 5+ years of spatially resolved lunar images in 23 VNIR and 9 SWIR filter bands at phase angles up to 90??. These images are calibrated to exoatmospheric radiance using nightly stellar observations in a band-coupled extinction algorithm and a radiometric scale based upon observations of the star Vega. An effort is currently underway to establish an absolute scale with direct traceability to NIST radiometric standards. The ROLO radiance model performs linear fitting of the spatially resolved lunar image data on an individual pixel basis. The results are radiance images directly comparable to spacecraft observations of the Moon. Model-generated radiance images have been produced for the ASTER lunar view conducted on 14 April 2003. The radiance model is still experimental - simplified photometric functions have been used, and initial results show evidence of computational instabilities, particularly at the lunar poles. The ROLO lunar image dataset is unique and extensive and presents opportunities for development of novel approaches to lunar photometric modeling.

  3. Radiance Data Products at the GES DAAC

    NASA Technical Reports Server (NTRS)

    Savtchenko, A.; Ouzounov, D.; Acker, J.; Johnson, J.; Leptoukh, G.; Qin, J.; Rui, H.; Smith, P.; Teng, W.

    2004-01-01

    The Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) has been archiving and distributing Radiance data, and serving science and application users of these data, for over 10 years now. The user-focused stewardship of the Radiance data from the AIRS, AVHRR, MODIS, SeaWiFS, SORCE, TOMS, TOVS, TRMM, and UARS instruments exemplifies the GES DAAC tradition and experience. Radiance data include raw radiance counts, onboard calibration data, geolocation products, radiometric calibrated and geolocated-calibrated radiance/reflectance. The number of science products archived at the GES DAAC is steadily increasing, as a result of more sophisticated sensors and new science algorithms. Thus, the main challenge for the GES DAAC is to guide users through the variety of Radiance data sets, provide tools to visualize and reduce the volume of the data, and provide uninterrupted access to the data. This presentation will describe the effort at the GES DAAC to build a bridge between multi-sensor data and the effective scientific use of the data, with an emphasis on the heritage of the science products. The intent is to inform users of the existence of this large collection of Radiance data; suggest starting points for cross-platform science projects and data mining activities; provide data services and tools information; and to give expert help in the science data formats and applications.

  4. Lunar absolute reflectance as observed by Chang'E-1 Imaging Interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jiang; Ling, ZongCheng; Liu, JianZhong; Wu, ZhongChen; Li, Bo; Ni, YuHeng

    2015-08-01

    Lunar absolute reflectance, which describes the fraction of solar radiation reflected by the Moon, is fundamental for the Chang'E-1 Imaging Interferometer (IIM) to map lunar mineralogical and elemental distributions. Recent observations made by the Spectral Irradiance Monitor (SIM) onboard the Solar Radiation and Climate Experiment (SORCE) spacecraft indicate that temporal variation in the solar radiation might have non-negligible influence on reflectance calculation, and the SIM measurements are different from the two previously used solar irradiances, i.e., ATLAS3 and Newkur. To provide reliable science results, we examined solar irradiance variability with the SIM daily observations, derived lunar absolute reflectances from the IIM 2A radiance with the SIM, ATLAS3 and Newkur data, and compared them with the Chandrayaan-1 Moon Mineralogy Mapper (M3), the Robotic Lunar Observatory (ROLO) and the Kaguya Multispectral Imager (MI) results. The temporal variability of the SIM solar irradiance is 0.25%-1.1% in the IIM spectral range, and less than 0.2% during the IIM observations. Nevertheless, the differences between the SIM measurements and the ATLAS3 and Newkur data can respectively rise up to 8% and 5% at particular IIM bands, resulting in discrepancy between which might affect compositional mapping. The IIM absolute reflectance we derived for the Moon using the SIM data, except for the last two bands, is consistent with the ROLO and the MI observations, although it is lower.

  5. Infrared radiance and solar glint at the ocean-sky horizon.

    PubMed

    Mermelstein, M D; Shettle, E P; Takken, E H; Priest, R G

    1994-09-01

    An analytic model is developed for the mean and clutter infrared radiance emitted from the ocean surface near the horizon and in the presence of solar glint. The model is based on the identification of a characteristic facet dimension over which the ocean surface is essentially flat. Fluctuations in the facet orientation generated by the water wave motion are modeled by a parameterized wave height power spectral density that provides the two orthogonal wave slope variances. The mean and root-meansquare facet radiances are calculated with Gaussian probability-density functions for the wave slopes. One can determine the number of facets within the field of view of a single detector by estimating the exposed ocean area and dividing by the facet area. This estimation takes into account shadowing effects of the swell wave, the swell wavelength, and the transverse detector field of view. The number of exposed facets together with the central-limit theorem permits computation of the radiance clutter as a function of look-down angle below the horizon. Vertical radiance profiles, parameterized by the azimuthal offset from the solar position, are calculated over a sensor look-down angle range of ±50 mrad about the horizon. The results of this analysis are compared with infrared radiance measurements of the ocean surface near the horizon and in the presence of solar glint. Agreement between the measured and calculated values of the mean and clutter radiances is good.

  6. Intercomparison of Laboratory Radiance Calibration Standards

    NASA Technical Reports Server (NTRS)

    Pavri, Betina; Chrien, Tom; Green, Robert; Williams, Orlesa

    2000-01-01

    Several standards for radiometric calibration were measured repeatedly with a spectroradiometer in order to understand how they compared in accuracy and stability. The tested radiance standards included a NIST 1000 W bulb and halon panel, two calibrated and stabilized integrating spheres, and a cavity blackbody. Results indicate good agreement between the blackbody and 1000 W bulb/spectralon panel, If these two radiance sources are assumed correct, then the integrating spheres did not conform. to their manufacturer-reported radiances in several regions of the spectrum. More detailed measurements am underway to investigate the discrepancy.

  7. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  8. The Intercalibration of Geostationary Visible Imagers Using Operational Hyperspectral SCIAMACHY Radiances

    NASA Technical Reports Server (NTRS)

    Doelling, David R.; Scarino, Benjamin R.; Morstad, Daniel; Gopalan, Arun; Bhatt, Rajendra; Lukashin, Constantine; Minnis, Patrick

    2013-01-01

    Spectral band differences between sensors can complicate the process of intercalibration of a visible sensor against a reference sensor. This can be best addressed by using a hyperspectral reference sensor whenever possible because they can be used to accurately mitigate the band differences. This paper demonstrates the feasibility of using operational Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) large-footprint hyperspectral radiances to calibrate geostationary Earth-observing (GEO) sensors. Near simultaneous nadir overpass measurements were used to compare the temporal calibration of SCIAMACHY with Aqua Moderate Resolution Imaging Spectroradiometer band radiances, which were found to be consistent to within 0.44% over seven years. An operational SCIAMACHY/GEO ray-matching technique was presented, along with enhancements to improve radiance pair sampling. These enhancements did not bias the underlying intercalibration and provided enough sampling to allow up to monthly monitoring of the GEO sensor degradation. The results of the SCIAMACHY/GEO intercalibration were compared with other operational four-year Meteosat-9 0.65-µm calibration coefficients and were found to be within 1% of the gain, and more importantly, it had one of the lowest temporal standard errors of all the methods. This is more than likely that the GEO spectral response function could be directly applied to the SCIAMACHY radiances, whereas the other operational methods inferred a spectral correction factor. This method allows the validation of the spectral corrections required by other methods.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Comparison of radiances observed from satellite and aircraft with calculations by using two atmospheric transmittance models.

    PubMed

    Murty, D G; Smith, W L; Woolf, H M; Hayden, C M

    1993-03-20

    An evaluation of two different atmospheric transmittance models is performed by using radiance data from the high-resolution infraRed Sounder (HIRS) instrument onboard the National Oceanic and Atmospheric Administration's NOAA-9 satellite and the airborne high-resolution interferometer sounder (HIS) instrument. Synthetic radiances have been derived from collocated radiosondes by using the television infrared observation satellite (TIROS) operational vertical sounder (TOVS) operational transmittance model and the fast atmospheric signature code (FASCOD2) line-by-line transmittance model for comparison with the two independent instrument observations. Radiance observations in various spectral channels from the HIRS and HIS instruments along with the synthetic radiances derived from the FASCOD2 and operational TOVS transmittance models are used for the performance evaluation. The results of the comparison reveal a significant discrepancy between 707 and 717 cm(-l) in the radiance calculation for both models. Exce llent agreement is observed between observation and calculation for the lower tropospheric long-wave temperature sounding channels. Serious problems are noted with the modeling of water vapor in the operational TOVS transmittance model. In addition, poor performance by FASCOD2 is revealed for the short-wavelength N(2)O-CO(2) HIRS spectral channels. In general the operational TOVS transmittance model is found to be only slightly inferior to the FASCOD2 model. Regarding the performance of the instruments, observations from the NOAA-9 HIRS and the aircraft HIS are comparable in terms of their agreement with theoretical computations.

  11. Towards high-accuracy primary spectral radiometry from 400 K to 1300 K.

    PubMed

    Yoon, H W; Khromchenko, V B; Eppeldauer, G P; Gibson, C E; Woodward, J T; Shaw, P S; Lykke, K R

    2016-03-28

    We describe the design, construction, calibration and use of a near-infrared thermodynamic radiation thermometer to measure blackbodies from 400 K to 1300 K. The motivation for this work is the pending redefinition of the kelvin and the need for direct, thermodynamic temperature measurements of the fixed-point blackbodies presently used in the realization of the temperature scale. The challenges of accurately measuring Planck radiances which vary greatly in radiance level and spectral shape are discussed. Methods to characterize the components used in the radiation thermometer design are described. The use of this radiation thermometer as a relative primary thermometer and the resulting residuals are shown. We describe radiometric calibration procedures for using the radiation thermometer as an absolute primary thermometer. Preliminary data showing the initial radiometric calibration steps are discussed. PMID:26903100

  12. In-progress absolute radiometric inflight calibration of the LANDSAT-4 sensors

    NASA Technical Reports Server (NTRS)

    Castle, K.; Dinguirard, M.; Ezra, C. E.; Holm, R. G.; Jackson, R. J.; Kastner, C. J.; Palmer, J. M.; Savage, R.; Slater, P. N.

    1983-01-01

    An approach is described for providing periodic inflight absolute radiometric calibrations of the LANDSAT-4 sensors by reference to selected, instrumented ground areas. Results of some early ground measurements and computer simulations are presented. Selection of a suitable ground reference site, accurate measurement of the spectral reflectance of the selected area, determination of atmospheric characteristics during the morning of the sensor overpass, reduction of the measured data and their use in an appropriate atmospheric radiative transfer program, and comparison of the radiance level data with the digital counts of for the images of the selected areas are discussed. Preliminary measurements of gypsum are being made as an aid in defining the characteristics of field equipment to be constructed and calibrated for use over the White Sands Missile Range.

  13. Polarized radiance fields under a dynamic ocean surface: a three-dimensional radiative transfer solution

    SciTech Connect

    You Yu; Zhai Pengwang; Kattawar, George W.; Yang Ping

    2009-06-01

    The hybrid matrix operator, Monte Carlo (HMOMC) method previously reported [Appl. Opt.47, 1063-1071 (2008)APOPAI0003-693510.1364/AO.47.001063] is improved by neglecting higher-order terms in the coupling of the matrix operators and by introducing a dual grid scheme. The computational efficiency for solving the vector radiative transfer equation in a full 3D coupled atmosphere-surface-ocean system is substantially improved, and, thus, large-scale simulations of the radiance distribution become feasible. The improved method is applied to the computation of the polarized radiance field under realistic surface waves simulated by the power spectral density method. To the authors' best knowledge, this is the first time that the polarized radiance field under a dynamic ocean surface and the underwater image of an object above such an ocean surface have been reported.

  14. Ocean color spectrum calculations. [theoretical models relating oceanographic parameters to upwelling radiances

    NASA Technical Reports Server (NTRS)

    Mccluney, W. R.

    1974-01-01

    The development is considered of procedures for measuring a number of subsurface oceanographic parameters using remotely sensed ocean color data. It is proposed that the first step in this effort should be the development of adequate theoretical models relating the desired oceanographic parameters to the upwelling radiances to be observed. A portion of a contributory theoretical model is shown to be described by a modified single scattering approach based upon a simple treatment of multiple scattering. The resulting quasi-single scattering model can be used to predict the upwelling distribution of spectral radiance emerging from the sea. The shape of the radiance spectrum predicted by this model for clear ocean water shows encouraging agreement with measurments made at the edge of the Sargasso Sea off Cape Hatteras.

  15. Absolute calibration of remote sensing instruments

    NASA Astrophysics Data System (ADS)

    Biggar, S. F.; Bruegge, C. J.; Capron, B. A.; Castle, K. R.; Dinguirard, M. C.; Holm, R. G.; Lingg, L. J.; Mao, Y.; Palmer, J. M.; Phillips, A. L.

    1985-12-01

    Source-based and detector-based methods for the absolute radiometric calibration of a broadband field radiometer are described. Using such a radiometer, calibrated by both methods, the calibration of the integrating sphere used in the preflight calibration of the Thematic Mapper was redetermined. The results are presented. The in-flight calibration of space remote sensing instruments is discussed. A method which uses the results of ground-based reflectance and atmospheric measurements as input to a radiative transfer code to predict the radiance at the instrument is described. A calibrated, helicopter-mounted radiometer is used to determine the radiance levels at intermediate altitudes to check the code predictions. Results of such measurements for the calibration of the Thematic Mapper on Landsat 5 and an analysis that shows the value of such measurements are described.

  16. Quantyfing the global lightning activity in absolute unints using Schumann resonance spectral decomposition method and the data from the World ELF Radiolocation Array

    NASA Astrophysics Data System (ADS)

    Dyrda, M.; Kulak, A.; Mlynarczyk, J.; Ostrowski, M.

    2015-12-01

    we derived the possible locations of the storm center on the African continent and hence we construct the 2D thunderstorms activity maps. Moreover, we calculated the thunderstorm intensities in absolute units C2 m2 s-1 and compared them with our previous findings [Dyrda et al., 2014].

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

    SciTech Connect

    Revercomb, H.E.; Knuteson, R.O.; Best, F.A.; Dirkx, T.P.

    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.

  18. Validation of AIRS Cloud Cleared Radiances Using MODIS and its Affect on QualityControl

    NASA Astrophysics Data System (ADS)

    Wilson, R. C.; Schreier, M. M.

    2015-12-01

    The Atmospheric Infrared Sounder (AIRS) was launched aboard the AQUA satellite to provide measurements of temperature, humidity, and various trace gases in support of climate research and weather prediction. Only clear sky measurements of the outgoing radiance are used in the AIRS physical retrieval of temperature, water vapor, and certain trace gases. To overcome cloud contamination the clear sky radiance is estimated using an iterative procedure that combines an initial estimate of the clear state from a neural network along with a three by three grid of AIRS measurements. The radiance error estimate, a component critical to the AIRS physical retrieval, must include contributions from all assumed parameters input to the forward model on top of instrument noise and amplification from cloud clearing. When the error estimate is too large the AIRS physical retrieval becomes over-constrained to the first guess profile. Therefore quantifying the cloud cleared error estimate is essential to an effective physical retrieval. We will validate the cloud-cleared radiances through the use of nearby clear ocean scenes and with comparisons to clear pixels from the Moderate Resolution Imaging Spectro-radiometer (MODIS). AIRS cloud cleared radiances are spectrally convolved to MODIS channels for this comparison. This analysis quantifies error due to cloud-clearing and demonstrates that clear MODIS pixels can be used with the standard AIRS quality control procedure to improve identification poor retrievals.

  19. [In-flight absolute radiometric calibration of UAV hyperspectral camera and its validation analysis].

    PubMed

    Gou, Zhi-yang; Yan, Lei; Chen, Wei; Jing, Xin; Yin, Zhong-yi; Duan, Yi-ni

    2012-02-01

    With the data in Urad Front Banner, Inner Mongolia on November 14th, 2010, hyper-spectral camera on UAV was calibrated adopting reflectance-based method. During the in-flight absolute radiometric calibration, 6 hyper-spectral radiometric gray-scale targets were arranged in the validation field. These targets' reflectances are 4.5%, 20%, 30%, 40%, 50% and 60% separately. To validate the calibration result, four extra hyper-spectral targets with sharp-edge spectrum were arranged to simulate the reflection and absorption peaks in natural objectives. With these peaks, the apparent radiance calculated by radiation transfer model and that calculated through calibration coefficients are much different. The result shows that in the first 15 bands (blue bands), errors are somewhat huge due to the noises of equipment. In the rest bands with quite even spectrum, the errors are small, most of which are less than 10%. For those bands with sharp changes in spectral curves, the errors are quite considerable, varying from 10% to 25%.

  20. Radiance calibration of the High Altitude Observatory white-light coronagraph on Skylab

    NASA Technical Reports Server (NTRS)

    Poland, A. I.; Macqueen, R. M.; Munro, R. H.; Gosling, J. T.

    1977-01-01

    The processing of over 35,000 photographs of the solar corona obtained by the white-light coronograph on Skylab is described. Calibration of the vast amount of data was complicated by temporal effects of radiation fog and latent image loss. These effects were compensated by imaging a calibration step wedge on each data frame. Absolute calibration of the wedge was accomplished through comparison with a set of previously calibrated glass opal filters. Analysis employed average characteristic curves derived from measurements of step wedges from many frames within a given camera half-load. The net absolute accuracy of a given radiance measurement is estimated to be 20%.

  1. Radiance from an ice contaminated surface

    NASA Astrophysics Data System (ADS)

    Arenberg, J.; Adamson, J.; Harpole, G.; Niedner, M.; Bowers, C.; Mehalick, K.; Lightsey, P.

    2016-07-01

    The formation of water ice on key thermal and optical surfaces is a factor in the design of the James Webb Space Telescope. Many of these concerns are related to the mid-infrared stray light performance of the system. In this paper, an expression for the radiance of a contaminated surface is formulated, including directional, film thickness and cooling effects. The resulting formula is then evaluated to show how radiance emanating from the surface changes for various thicknesses of the ice layer as a function wavelength and the local thermal environment. This paper concludes with an analysis and discussion of this complex behavior.

  2. Far-infrared sensor for cirrus (FIRSC): an aircraft-based Fourier-transform spectrometer to measure cloud radiance.

    PubMed

    Vanek, M D; Nolt, I G; Tappan, N D; Ade, P A; Gannaway, F C; Hamilton, P A; Lee, C; Davis, J E; Predko, S

    2001-05-01

    We describe an aircraft-based Fourier-transform spectrometer (FTS) designed to measure the Earth outgoing radiance spectrum in the far-infrared-submillimeter spectral range. The instrument features include a rapid-scan FTS to obtain high spatial resolution from a moving aircraft platform, a sensitive two-channel detector, and a CCD camera for recording the nadir cloud scene with each scan record. Such measurements demonstrate the sensitivity of Earth radiance to high clouds and provide spectral data for improving techniques for remote sensing and retrieval of atmospheric and cloud properties.

  3. Determining index of refraction from polarimetric hyperspectral radiance measurements

    NASA Astrophysics Data System (ADS)

    Martin, Jacob A.; Gross, Kevin C.

    2015-09-01

    Polarimetric hyperspectral imaging (P-HSI) combines two of the most common remote sensing modalities. This work leverages the combination of these techniques to improve material classification. Classifying and identifying materials requires parameters which are invariant to changing viewing conditions, and most often a material's reflectivity or emissivity is used. Measuring these most often requires assumptions be made about the material and atmospheric conditions. Combining both polarimetric and hyperspectral imaging, we propose a method to remotely estimate the index of refraction of a material. In general, this is an underdetermined problem because both the real and imaginary components of index of refraction are unknown at every spectral point. By modeling the spectral variation of the index of refraction using a few parameters, however, the problem can be made overdetermined. A number of different functions can be used to describe this spectral variation, and some are discussed here. Reducing the number of spectral parameters to fit allows us to add parameters which estimate atmospheric downwelling radiance and transmittance. Additionally, the object temperature is added as a fit parameter. The set of these parameters that best replicate the measured data is then found using a bounded Nelder-Mead simplex search algorithm. Other search algorithms are also examined and discussed. Results show that this technique has promise but also some limitations, which are the subject of ongoing work.

  4. Use of near infrared/red radiance ratios for estimating vegetation biomass and physiological status

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.

    1977-01-01

    The application of photographic infrared/red (ir/red) reflectance or radiance ratios for the estimation of vegetation biomass and physiological status were investigated by analyzing in situ spectral reflectance data from experimental grass plots. Canopy biological samples were taken for total wet biomass, total dry biomass, leaf water content, dry green biomass, dry brown biomass, and total chlorophyll content at each sampling date. Integrated red and photographic infrared radiances were regressed against the various canopy or plot variables to determine the relative significance between the red, photographic infrared, and the ir/red ratio and the canopy variables. The ir/red ratio is sensitive to the photosynthetically active or green biomass, the rate of primary production, and actually measures the interaction between the green biomass and the rate of primary production within a given species type. The ir/red ratio resulted in improved regression significance over the red or the ir/radiances taken separately. Only slight differences were found between ir/red ratio, the ir-red difference, the vegetation index, and the transformed vegetation index. The asymptotic spectral radiance properties of the ir, red, ir/red ratio, and the various transformations were evaluated.

  5. Elimination of environmental effects from Landsat radiance data

    NASA Technical Reports Server (NTRS)

    Kim, S. T.; Smith, D. W.

    1979-01-01

    A critical problem involved in quantitative multi-temporal sensing of the physical processes with Landsat is the fact that variations in the spectral signatures for a given target of interest result from a combined effect of target properties and the environmental factors such as sun angles, atmospheric conditions, etc. at the time of an overpass. In an attempt to solve the problem, a transformation procedure is developed to remove the environmental effects from the MSS radiance data. Mathematical derivation of the transformation procedure is elaborated and an example of testing the procedure is illustrated using suspended sediments reflectance data obtained by Landsat MSS during four different overpasses over the lower Mississippi River valley.

  6. Assimilation of the Microwave Limb Sounder Radiances

    NASA Technical Reports Server (NTRS)

    Wargan, K.; Read, W.; Livesey, N.; Wagner, P.; Nguyen. H.; Pawson, S.

    2012-01-01

    It has been shown that the assimilation of limb-sounder data can significantly improve the representation of ozone in NASA's GEOS Data Assimilation Systems (GEOS-DAS), particularly in the stratosphere. The studies conducted so far utilized retrieved data from the MIPAS, POAM, ILAS and EOS Microwave Limb Sounder (EOS MLS) instruments. Direct assimilation of the radiance data can be seen as the natural next step to those studies. The motivation behind working with radiances is twofold. First, retrieval algorithms use a priori data which are either climatological or are obtained from previous analyses. This introduces additional uncertainty and, in some cases, may lead to "self-contamination"- when the a priori is taken from the same assimilation system in which subsequently ingests the retrieved observations. Second, radiances can be available in near real time thus providing an opportunity for operational assimilation, which could help improve the use of infrared radiance instruments from operational satellite instruments. In this presentation we summarize our ongoing work on an implementation of the assimilation of EOS MLS radiances into the GEOS-5 DAS. This work focuses on assimilation of band 7 brightness temperatures which are sensitive to ozone. Our implementation uses the MLS Callable Forward Model developed by the MLS team at NASA JPL as the observation operator. We will describe our approach and recent results which are not yet final. In particular, we will demonstrate that this approach has a potential to improve the vertical structure of ozone in the lower tropical stratosphere as compared with the retrieved MLS product. We will discuss the computational efficiency of this implementation.

  7. Laboratory measurements of upwelled radiance and reflectance spectra of Calvert, Ball, Jordan, and Feldspar soil sediments

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Usry, J. W.; Witte, W. G.; Gurganus, E. A.

    1977-01-01

    An effort to investigate the potential of remote sensing for monitoring nonpoint source pollution was conducted. Spectral reflectance characteristics for four types of soil sediments were measured for mixture concentrations between 4 and 173 ppm. For measurements at a spectral resolution of 32 mm, the spectral reflectances of Calvert, Ball, Jordan, and Feldspar soil sediments were distinctly different over the wavelength range from 400 to 980 nm at each concentration tested. At high concentrations, spectral differences between the various sediments could be detected by measurements with a spectral resolution of 160 nm. At a low concentration, only small differences were observed between the various sediments when measurements were made with 160 nm spectral resolution. Radiance levels generally varied in a nonlinear manner with sediment concentration; linearity occurred in special cases, depending on sediment type, concentration range, and wavelength.

  8. BOREAS RSS-2 Level-1B ASAS Image Data: At-Sensor Radiance in BSQ Format

    NASA Technical Reports Server (NTRS)

    Russell, C.; Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Dabney, P. W.; Kovalick, W.; Graham, D.; Bur, Michael; Irons, James R.; Tierney, M.

    2000-01-01

    The BOREAS RSS-2 team used the ASAS instrument, mounted on the NASA C-130 aircraft, to create at-sensor radiance images of various sites as a function of spectral wavelength, view geometry (combinations of view zenith angle, view azimuth angle, solar zenith angle, and solar azimuth angle), and altitude. The level-1b ASAS images of the BOREAS study areas were collected from April to September 1994 and March to July 1996.

  9. A Hand Held Ratioing Radiometer for remote radiance measurements

    NASA Technical Reports Server (NTRS)

    Daubner, L.; Davies, J.; Cumming, C.; Goetz, A.

    1982-01-01

    The small, lightweight Hand Held Ratioing Radiometer (HHRR) measures the ratio of spectral reflectance in any of 25 pairs of narrow bands in the 400 to 2500 nanometer spectral region. Two parallel optical trains view the scene through separate filters mounted in two filter wheels each containing five filters. Absolute reflectance of the scene can also be measured. HHRR is particularly useful for ground truth studies for the interpretation of imagery from Landsat, the thematic mappers and the forthcoming SPOT satellite. Its small size and simplicity of operation make it useful to geologists, botanists, oceanographers and many other geotechnologists.

  10. Estimation of evapotranspiration using satellite TOA radiances

    NASA Astrophysics Data System (ADS)

    Peng, J.; Loew, A.

    2013-12-01

    ET (Evapotranspiration) is an important variable in the water and energy balance on the Earth's surface. Accurate estimation of the temporal and spatial pattern of ET is of great significance for hydrological, agricultural and meteorological studies. A simplified single-source energy balance parameterization scheme, known as the LST/NDVI (Land Surface Temperature/Normalized Difference Vegetation Index) feature space method, has been applied successfully to estimate clear sky ET in many studies. Based on the LST/NDVI feature space method, a new method is proposed in this study to estimate ET directly using the TOA (Top of Atmosphere) radiances without performing atmospheric correction and associated complex processes. Firstly, the feasibility and uncertainties in estimating NDTI (Normalized Difference Temperature Index, a key parameter in EF (evaporative fraction) estimation) from TOA radiances are investigated. Through a physical understanding of the Planck radiation law and radiative transfer equation, together with a detailed sensitivity analysis of NDTI on surface and atmosphere variability, it is found that the NDTI can be estimated from TOA radiances with an accuracy of 90% if the spatial variabilities of atmospheric parameters (water vapor, effective atmospheric temperature) and surface emissivity are below 10%, 4 K, and 0.05, respectively. Then the applicability and robustness of the MODIS TOA radiances based EF estimation scheme are investigated using FLUXNET (a global network of eddy covariance stations) observations. From direct comparison with measured EF at different FLUXNET sites, the estimated EF from TOA radiances perform mostly well across a wide variety of climate and biome types. The accuracy level is also comparable with published results in the literature. Furthermore, the FLUXNET measurements are used to examine the assumption of EF self preservation, and the conditions under which it can hold. It is found that the instantaneous EF can

  11. Validation of the Atmospheric Infrared Sounder (AIRS) over the Antarctic Plateau: Low Radiance, Low Humidity, and Thin Clouds

    NASA Technical Reports Server (NTRS)

    Tobin, David C.

    2005-01-01

    The main goal of the project has been to use specialized measurements collected at the Antarctic Plateau to provide validation of the Atmospheric InfraRed Sounder (AIRS) spectral radiances and some AIRS Level 2 products. As proposed, efforts conducted at the University of Wisconsin are focused on providing technical information, data, and software in support of the validation studies.

  12. Extraction of Profile Information from Cloud Contaminated Radiances. Appendixes 2

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Zhou, D. K.; Huang, H.-L.; Li, Jun; Liu, X.; Larar, A. M.

    2003-01-01

    Clouds act to reduce the signal level and may produce noise dependence on the complexity of the cloud properties and the manner in which they are treated in the profile retrieval process. There are essentially three ways to extract profile information from cloud contaminated radiances: (1) cloud-clearing using spatially adjacent cloud contaminated radiance measurements, (2) retrieval based upon the assumption of opaque cloud conditions, and (3) retrieval or radiance assimilation using a physically correct cloud radiative transfer model which accounts for the absorption and scattering of the radiance observed. Cloud clearing extracts the radiance arising from the clear air portion of partly clouded fields of view permitting soundings to the surface or the assimilation of radiances as in the clear field of view case. However, the accuracy of the clear air radiance signal depends upon the cloud height and optical property uniformity across the two fields of view used in the cloud clearing process. The assumption of opaque clouds within the field of view permits relatively accurate profiles to be retrieved down to near cloud top levels, the accuracy near the cloud top level being dependent upon the actual microphysical properties of the cloud. The use of a physically correct cloud radiative transfer model enables accurate retrievals down to cloud top levels and below semi-transparent cloud layers (e.g., cirrus). It should also be possible to assimilate cloudy radiances directly into the model given a physically correct cloud radiative transfer model using geometric and microphysical cloud parameters retrieved from the radiance spectra as initial cloud variables in the radiance assimilation process. This presentation reviews the above three ways to extract profile information from cloud contaminated radiances. NPOESS Airborne Sounder Testbed-Interferometer radiance spectra and Aqua satellite AIRS radiance spectra are used to illustrate how cloudy radiances can be used

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Using radiance of cloud shadow for retrieve Investigation of AOD retrieval with Himawari-8 satellite data

    NASA Astrophysics Data System (ADS)

    Sun, Ta-Min; Chang, Yuan-Hsiang; Chang, Kuo-En; Lin, Tang-Huang

    2016-04-01

    As we know, the emission of pollutants, such as dust storm, biomass burning and anthropogenic pollution are serious issues related to the environmental change and human health topics in Asia. With the high temporal observation over a broad area, the new generated geostationary satellite, Himawari-8 (H-8) seems to be a good choice for atmospheric pollution monitor. It can provide the observation over Asia with 16 bands in visible and thermal infrared spectral every 10 minutes. For the atmospheric pollutant monitor by means of remote sensing, the retrieval of aerosol optical depth (AOD) is the most important index. In this study, the long method is employed for AOD retrieval which depends on the path radiance significantly. Apparent radiance of the suitable cloud shadow is selected as the path radiance. In order to let the atmospheric pollution monitor is used efficiently, so the distribution of the path radiance is using the objective analysis to expand it. The results of AOD retrieval from H-8 visible data are well consistent with MODIS (Moderate Resolution Imaging Spectroradiometer) AOD products and ground measurements AERONET (Aerosol Robotic Networks), indicating the practical of proposed approach for the AOD retrieval with H-8 data.

  15. Remote Sensing of Cloud Properties using Ground-based Measurements of Zenith Radiance

    NASA Technical Reports Server (NTRS)

    Chiu, J. Christine; Marshak, Alexander; Knyazikhin, Yuri; Wiscombe, Warren J.; Barker, Howard W.; Barnard, James C.; Luo, Yi

    2006-01-01

    An extensive verification of cloud property retrievals has been conducted for two algorithms using zenith radiances measured by the Atmospheric Radiation Measurement (ARM) Program ground-based passive two-channel (673 and 870 nm) Narrow Field-Of-View Radiometer. The underlying principle of these algorithms is that clouds have nearly identical optical properties at these wavelengths, but corresponding spectral surface reflectances (for vegetated surfaces) differ significantly. The first algorithm, the RED vs. NIR, works for a fully three-dimensional cloud situation. It retrieves not only cloud optical depth, but also an effective radiative cloud fraction. Importantly, due to one-second time resolution of radiance measurements, we are able, for the first time, to capture detailed changes in cloud structure at the natural time scale of cloud evolution. The cloud optical depths tau retrieved by this algorithm are comparable to those inferred from both downward fluxes in overcast situations and microwave brightness temperatures for broken clouds. Moreover, it can retrieve tau for thin patchy clouds, where flux and microwave observations fail to detect them. The second algorithm, referred to as COUPLED, couples zenith radiances with simultaneous fluxes to infer 2. In general, the COUPLED and RED vs. NIR algorithms retrieve consistent values of tau. However, the COUPLED algorithm is more sensitive to the accuracies of measured radiance, flux, and surface reflectance than the RED vs. NIR algorithm. This is especially true for thick overcast clouds where it may substantially overestimate z.

  16. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  17. Improving AIRS radiance spectra in high contrast scenes using MODIS

    NASA Astrophysics Data System (ADS)

    Pagano, Thomas S.; Aumann, Hartmut H.; Manning, Evan M.; Elliott, Denis A.; Broberg, Steven E.

    2015-09-01

    The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in 2378 channels ranging in wavelength from 3.7-15.4 um with spectral resolution of better than 1200, and spatial resolution of 13.5 km with global daily coverage. The AIRS is designed to measure temperature and water vapor profiles for improvement in weather forecast accuracy and improved understanding of climate processes. As with most instruments, the AIRS Point Spread Functions (PSFs) are not the same for all detectors. When viewing a non-uniform scene, this causes a significant radiometric error in some channels that is scene dependent and cannot be removed without knowledge of the underlying scene. The magnitude of the error depends on the combination of non-uniformity of the AIRS spatial response for a given channel and the non-uniformity of the scene, but is typically only noticeable in about 1% of the scenes and about 10% of the channels. The current solution is to avoid those channels when performing geophysical retrievals. In this effort we use data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument to provide information on the scene uniformity that is used to correct the AIRS data. For the vast majority of channels and footprints the technique works extremely well when compared to a Principal Component (PC) reconstruction of the AIRS channels. In some cases where the scene has high inhomogeneity in an irregular pattern, and in some channels, the method can actually degrade the spectrum. Most of the degraded channels appear to be slightly affected by random noise introduced in the process, but those with larger degradation may be affected by alignment errors in the AIRS relative to MODIS or uncertainties in the PSF. Despite these errors, the methodology shows the ability to correct AIRS radiances in non-uniform scenes under some of the worst case conditions and improves the ability to match

  18. Use of computer-simulated radiances to retrieve total atmospheric ozone data from satellite-mounted infrared multifilter radiometers

    NASA Astrophysics Data System (ADS)

    Weidhaas, P. P.

    1980-10-01

    Four satellites equipped with multichannel filter radiometer (MFR) sensors supplied infrared radiance data at various spectral channels. An ozone retrieval model was developed in order to derive total ozone values from the radiance data. Statistical comparison against a network of ground observatories which measure total ozone with a Dobson spectrophotometer showed good agreement between MFR derived ozone data and Dobson measurements. Thus, the scientific feasibility of the ozone retrieval model was established. Currently, SOAC has begun to automate the processing and archiving of the MFR data.

  19. Relationships between chlorophyll density and ocean radiance as measured by U2/OCS: Algorithms, examples and comparison

    NASA Technical Reports Server (NTRS)

    Kim, H. H.; Hart, W. D.

    1983-01-01

    An ocean atmosphere radiative transfer process computation method which is suitable for determining lower boundary ocean albedo and other radiation components from spectral measurements of upwelling radiance taken from a high altitude platform is described. The method was applied to a set of color scanner data taken from slope water of the South Atlantic Bight to determine the influence of cholorophyll-a pigments in the sea on the ratio of upwelling radiance to down welling irradiance as a function of wavelength. The resulting chlorophyll concentrations are compared with measurements made by ships stationed along the flight path.

  20. Retrieving Temperature and Moisture Profiles from AERI Radiance Observations: AERIPROF Value-Added Product Technical Description Revision 1

    SciTech Connect

    WF Feltz; HB Howell; RO Knuteson; JM Comstock; R Mahon; DD Turner; WL Smith; HM Woolf; C Sivaraman; TD Halter

    2007-04-30

    This document explains the procedure to retrieve temperature and moisture profiles from high-spectral resolution infrared radiance data measured by the U.S. Department Of Energy (DOE) Atmospheric Radiation (ARM) Program’s atmospheric emitted radiance interferometer (AERI) instrument. The technique has been named the AERIPROF thermodynamic retrieval algorithm. The software has been developed over the last decade at the University of Wisconsin-Madison and has matured into an ARM Value-Added Procedure. This document will describe the AERIPROF retrieval procedure, outline the algorithm routines, discuss the software heritage, and, finally, provide references with further documentation.

  1. Climate Quality Broadband and Narrowband Solar Reflected Radiance Calibration Between Sensors in Orbit

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Doelling, David R.; Young, David F.; Loeb, Norman G.; Garber, Donald P.; MacDonnell, David G.

    2008-01-01

    vAs the potential impacts of global climate change become more clear [1], the need to determine the accuracy of climate prediction over decade-to-century time scales has become an urgent and critical challenge. The most critical tests of climate model predictions will occur using observations of decadal changes in climate forcing, response, and feedback variables. Many of these key climate variables are observed by remotely sensing the global distribution of reflected solar spectral and broadband radiance. These "reflected solar" variables include aerosols, clouds, radiative fluxes, snow, ice, vegetation, ocean color, and land cover. Achieving sufficient satellite instrument accuracy, stability, and overlap to rigorously observe decadal change signals has proven very difficult in most cases and has not yet been achieved in others [2]. One of the earliest efforts to make climate quality observations was for Earth Radiation Budget: Nimbus 6/7 in the late 1970s, ERBE in the 1980s/90s, and CERES in 2000s are examples of the most complete global records. The recent CERES data products have carried out the most extensive intercomparisons because if the need to merge data from up to 11 instruments (CERES, MODIS, geostationary imagers) on 7 spacecraft (Terra, Aqua, and 5 geostationary) for any given month. In order to achieve climate calibration for cloud feedbacks, the radiative effect of clear-sky, all-sky, and cloud radiative effect must all be made with very high stability and accuracy. For shortwave solar reflected flux, even the 1% CERES broadband absolute accuracy (1-sigma confidence bound) is not sufficient to allow gaps in the radiation record for decadal climate change. Typical absolute accuracy for the best narrowband sensors like SeaWiFS, MISR, and MODIS range from 2 to 4% (1-sigma). IPCC greenhouse gas radiative forcing is approx. 0.6 W/sq m per decade or 0.6% of the global mean shortwave reflected flux, so that a 50% cloud feedback would change the global

  2. Use of computer-simulated radiances to retrieve total atmospheric ozone data from satellite-mounted infrared multifilter radiometers

    SciTech Connect

    Weidhaas, P.P.

    1980-10-01

    Between March 1977 and February 1980, four satellites equipped with multichannel filter radiometer (MFR) sensors supplied infrared radiance data at various spectral channels. The Satellite Ozone Analysis Center (SOAC) at the Lawrence Livermore National Laboratory received the radiance data from the US Air Force. An ozone retrieval model was developed by SOAC in order to derive total ozone values from the radiance data. Statistical comparison against a network of ground observatories which measure total ozone with a Dobson spectrophotometer showed good agreement between MFR-derived ozone data and Dobson measurements. Thus, the scientific feasibility of SOAC's ozone retrieval model was established. Currently, SOAC has begun to automate the processing and archiving of the MFR data. Daily computer-generated contour maps of the global ozone distribution will be produced for dissemination to the scientific community. Extensive data analysis is also in progress.

  3. Laboratory measurements of radiance and reflectance spectra of dilute secondary-treated sewage sludge

    NASA Technical Reports Server (NTRS)

    Witte, W. G.; Usry, J. W.; Whitlock, C. H.; Gurganus, E. A.

    1977-01-01

    The National Aeronautics and Space Administration (NASA), in cooperation with the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), conducted a research program to evaluate the feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge. One aspect of the research program involved the measurements of upwelled spectral signatures for sewage-sludge mixtures of different concentrations in an 11600-liter tank. This paper describes the laboratory arrangement and presents radiance and reflectance spectra in the visible and near-infrared ranges for concentrations ranging from 9.7 to 180 ppm of secondary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled radiance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations.

  4. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  5. Determination and error analysis of emittance and spectral emittance measurements by remote sensing. [of leaves, soil and plant canopies

    NASA Technical Reports Server (NTRS)

    Kumar, R.

    1977-01-01

    Theoretical and experimental determinations of the emittance of soils and leaves are reviewed, and an error analysis of emittance and spectral emittance measurements is developed as an aid to remote sensing applications. In particular, an equation for the upper bound of the absolute error in an emittance determination is derived. The absolute error is found to decrease with an increase in contact temperature and to increase with an increase in environmental integrated radiant flux density. The difference between temperature and band radiance temperature is plotted as a function of emittance for the wavelength intervals 4.5 to 5.5 microns, 8 to 13.5 microns and 10.2 to 12.5 microns.

  6. High temperature radiance spectroscopy measurements of solid and liquid uranium and plutonium carbides

    NASA Astrophysics Data System (ADS)

    Manara, D.; De Bruycker, F.; Boboridis, K.; Tougait, O.; Eloirdi, R.; Malki, M.

    2012-07-01

    In this work, an experimental study of the radiance of liquid and solid uranium and plutonium carbides at wavelengths 550 nm ⩽ λ ⩽ 920 nm is reported. A fast multi-channel spectro-pyrometer has been employed for the radiance measurements of samples heated up to and beyond their melting point by laser irradiation. The melting temperature of uranium monocarbide, soundly established at 2780 K, has been taken as a radiance reference. Based on it, a wavelength-dependence has been obtained for the high-temperature spectral emissivity of some uranium carbides (1 ⩽ C/U ⩽ 2). Similarly, the peritectic temperature of plutonium monocarbide (1900 K) has been used as a reference for plutonium monocarbide and sesquicarbide. The present spectral emissivities of solid uranium and plutonium carbides are close to 0.5 at 650 nm, in agreement with previous literature values. However, their high temperature behaviour, values in the liquid, and carbon-content and wavelength dependencies in the visible-near infrared range have been determined here for the first time. Liquid uranium carbide seems to interact with electromagnetic radiation in a more metallic way than does the solid, whereas a similar effect has not been observed for plutonium carbides. The current emissivity values have also been used to convert the measured radiance spectra into real temperature, and thus perform a thermal analysis of the laser heated samples. Some high-temperature phase boundaries in the systems U-C and Pu-C are shortly discussed on the basis of the current results.

  7. Spectral-based inferential measurement of grey-body's temperature

    NASA Astrophysics Data System (ADS)

    Zheng, Feng; Liu, Liying; Zhu, Lingxi; Huan, Kewei; Li, Ye; Shi, Xiaoguang

    2015-11-01

    Aiming at the problems of temperature measurement and the defects of radiance thermometry theory, one method of spectral-based inferential measurement is proposed, which adopts the Empirical Risk Minimization (ERM) functional model as the temperature measurement model. Then, the radiance thermometry theory and inferential measurement technology are discussed comparatively. Temperatures of some targets, such and tungsten lamp and solar surface, are measured by spectral-based inferential measurement.

  8. Evaluation of ISCCP multisatellite radiance calibration for geostationary imager visible channels using the moon

    USGS Publications Warehouse

    Stone, Thomas C.; William B. Rossow,; Joseph Ferrier,; Laura M. Hinkelman,

    2013-01-01

    Since 1983, the International Satellite Cloud Climatology Project (ISCCP) has collected Earth radiance data from the succession of geostationary and polar-orbiting meteorological satellites operated by weather agencies worldwide. Meeting the ISCCP goals of global coverage and decade-length time scales requires consistent and stable calibration of the participating satellites. For the geostationary imager visible channels, ISCCP calibration provides regular periodic updates from regressions of radiances measured from coincident and collocated observations taken by Advanced Very High Resolution Radiometer instruments. As an independent check of the temporal stability and intersatellite consistency of ISCCP calibrations, we have applied lunar calibration techniques to geostationary imager visible channels using images of the Moon found in the ISCCP data archive. Lunar calibration enables using the reflected light from the Moon as a stable and consistent radiometric reference. Although the technique has general applicability, limitations of the archived image data have restricted the current study to Geostationary Operational Environmental Satellite and Geostationary Meteorological Satellite series. The results of this lunar analysis confirm that ISCCP calibration exhibits negligible temporal trends in sensor response but have revealed apparent relative biases between the satellites at various levels. However, these biases amount to differences of only a few percent in measured absolute reflectances. Since the lunar analysis examines only the lower end of the radiance range, the results suggest that the ISCCP calibration regression approach does not precisely determine the intercept or the zero-radiance response level. We discuss the impact of these findings on the development of consistent calibration for multisatellite global data sets.

  9. Spectral measurements of ocean-dumped wastes tested in the marine upwelled spectral signature laboratory

    NASA Technical Reports Server (NTRS)

    Witte, W. G.; Usry, J. W.; Whitlock, C. H.; Gurganus, E. A.

    1979-01-01

    Transmission and inherent upwelled radiance measurements were made of various mixtures of three ocean-dumped industrial plant wastes in artificial seawater. Laboratory analyses were made of the physical and chemical properties of the various mixtures. These results and the laboratory measurements of beam attenuation and inherent upwelled radiance indicate a variety of chemical and spectral responses when industrial wastes are added to artificial seawater. In particular, increased levels of turbidity did not always cause increased levels of inherent reflectance.

  10. Transmittance and Radiance Computations for Rocket Engine Plume Environments

    NASA Technical Reports Server (NTRS)

    Tejwani, Gopal D.

    2003-01-01

    Emission and absorption characteristics of several atmospheric and combustion species have been studied and are presented with reference to rocket engine plume environments. The effects of clous, rain, and fog on plume radiance/transmittance has also been studied.Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.

  11. Spatial Heterogeneity of Reflected Radiance from Globally Distributed Clouds

    SciTech Connect

    Genkova, Iliana S.; Davies, Roger

    2003-11-06

    Reflected spectral radiance measured by the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite has been analyzed to determine the fraction of global cloudiness that appears to be spatially homogeneous over regions of specified size. We exclude scenes with reflectivities less than 0.2, and high latitudes to avoid snow and ice. About 1.4±0.3%, or 1 in 70, of 8.8 km cloudy regions measured at 275 m have a range of reflectivities less than ±5% of their central value. This pass rate changes slightly with viewing angle, and is sensitive to the size of the test window, rising to 11% for 1.1 km regions. It rises to a value of 2.3 ± 0.5% for 8.8 km regions if the measurement resolution is degraded to 1100 m. For the purposes of this study “global” cloudiness is limited to mid-morning clouds.

  12. A SWIR radiance model for cockpit instrumentation

    NASA Astrophysics Data System (ADS)

    Green, John; Robinson, Tim

    2013-06-01

    Night Vision Imaging Systems technology is advancing at a rapid pace. These advances can be broadly divided in two distinct categories; performance and data management. There is an encouraging trend towards higher sensitivity, better resolution, and lower power consuming devices. These improvements, coupled with the shift from analog to digital data output, promise to provide a powerful night vision device. Given a digital system, the data can be managed to enhance the pilot's view (image processing), overlay data from multiple sensors (image fusion), and send data to remote locations for analysis (image sharing). The US Air Force Research Laboratory (AFRL) has an active program to introduce a helmet mounted digital imaging system that extends the detection range from the near infrared (NIR) band to the short-wave infrared (SWIR) band. Aside from the digital output, part of the motivation to develop a SWIR imaging system includes the desire to exploit the SWIR ambient night glow spectrum, see through some levels of fog and haze, and use a robust sensor technology suitable for 24 hours per day imaging. Integrating this advanced SWIR imaging system into a cockpit presents some human factor issues. Light emitted from illuminated instruments may hinder the performance of the imaging system, reducing the pilot's ability to detect lowvisible objects at night. The transmission of light through cockpit transparencies and through the atmosphere may also impact performance. In this paper we propose a model that establishes cockpit lighting SWIR radiance limits, much like MIL-STD-3009 specifies NVIS radiance limits for NVGs. This model is the culmination of a two year program sponsored by AFRL.

  13. Application of oxygen A-band equivalent width to disambiguate downwelling radiances for cloud optical depth measurement

    NASA Astrophysics Data System (ADS)

    Niple, Edward R.; Scott, Herman E.; Conant, John A.; Jones, Stephen H.; Iannarilli, Frank J.; Pereira, Wellesley E.

    2016-08-01

    This paper presents the three-waveband spectrally agile technique (TWST) for measuring cloud optical depth (COD). TWST is a portable field-proven sensor and retrieval method offering a unique combination of fast (1 Hz) cloud-resolving (0.5° field of view) real-time-reported COD measurements. It entails ground-based measurement of visible and near-infrared (VNIR) zenith spectral radiances much like the Aerosol Robotic Network (AERONET) cloud-mode sensors. What is novel in our approach is that we employ absorption in the oxygen A-band as a means of resolving the COD ambiguity inherent in using up-looking spectral radiances. We describe the TWST sensor and algorithm, and assess their merits by comparison to AERONET cloud-mode measurements collected during the US Department of Energy's Atmospheric Radiation Measurements (ARM) Two-Column Aerosol Project (TCAP). Spectral radiance agreement was better than 1 %, while a linear fit of COD yielded a slope of 0.905 (TWST reporting higher COD) and offset of -2.1.

  14. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  15. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

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

    PubMed

    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. PMID:25709450

  17. A method of reducing background radiance for emissivity-compensated radiation thermometry of silicon wafers.

    PubMed

    Iuchi, T; Toyoda, Y; Seo, T

    2013-02-01

    We studied the spectral and directional emissivities of silicon wafers using an optical polarization technique. Based on simulation and experimental results, we developed two radiation thermometry methods for silicon wafers: one is based on the polarized emissivity-invariant condition and the other is based on the relationship between the ratio of the p- and s-polarized radiance and the polarized emissivity. These methods can be performed at temperatures above 600 °C and over a wide wavelength range (0.9-4.8 μm), irrespective of the dielectric film thickness and the substrate resistivity, which depends on the dopant concentration. The temperature measurements were estimated to have expanded uncertainties (k = 2) of less than 5 °C. With a view to practically applying these methods, we investigated a method to reduce the intense background radiance produced by high-intensity heating lamps. We found that the background radiance can be greatly reduced by using a radiometer that is sensitive to wavelengths of 4.5 or 4.8 μm and suitable geometrical arrangements of a quartz plate. This opens up the possibility of using the two proposed radiation thermometry methods in practical applications.

  18. Assimilation of SBUV Version 8 Radiances into the GEOS Ozone DAS

    NASA Technical Reports Server (NTRS)

    Mueller, Martin D.; Stajner, Ivanka; Bhartia, Pawan K.

    2004-01-01

    In operational weather forecasting, the assimilation of brightness temperatures from satellite sounders, instead of assimilation of 1D-retrievals has become increasingly common practice over the last two decades. Compared to these systems, assimilation of trace gases is still at a relatively early stage of development, and efforts to directly assimilate radiances instead of retrieved products have just begun a few years ago, partially because it requires much more computation power due to the employment of a radiative transport forward model (FM). This paper will focus on a method to assimilate SBUV/2 radiances (albedos) into the Global Earth Observation System Ozone Data Assimilation Scheme (GEOS-03DAS). While SBUV-type instruments cannot compete with newer sensors in terms of spectral and horizontal resolution, they feature a continuous data record back to 1978, which makes them very valuable for trend studies. Assimilation can help spreading their ground coverage over the whole globe, as has been previously demonstrated with the GEOS-03DAS using SBUV Version 6 ozone profiles. Now, the DAS has been updated to use the newly released SBUV Version 8 data. We will compare pre]lmlnarv results of SBUV radiance assimilation with the assimilation of retrieved ozone profiles, discuss methods to deal with the increased computational load, and try to assess the error characteristics and future potential of the new approach.

  19. An Investigation of the Characterization of Cloud Contamination in Hyperspectral Radiances

    NASA Technical Reports Server (NTRS)

    McCarty, William; Jedlovec, Gary J.; LeMarshall, John

    2007-01-01

    In regions lacking direct observations, the assimilation of radiances from infrared and microwave sounders is the primary method for characterizing the atmosphere in the analysis process. In recent years, technological advances have led to the launching of more advanced sounders, particularly in the thermal infrared spectrum. With the advent of these hyperspectral sounders, the amount of data available for the analysis process has and will continue to be dramatically increased. However, the utilization of infrared radiances in variational assimilation can be problematic in the presence of clouds; specifically the assessment of the presence of clouds in an instantaneous field of view (IFOV) and the contamination in the individual channels within the IFOV. Various techniques have been developed to determine if a channel is contaminated by clouds. The work presented in this paper and subsequent presentation will investigate traditional techniques and compare them to a new technique, the C02 sorting technique, which utilizes the high spectral resolution of the Atmospheric Infrared Sounder (AIRS) within the framework of the Gridpoint Statistical Interpolation (GSI) 3DVAR system. Ultimately, this work is done in preparation for the assessment of short-term forecast impacts with the regional assimilation of AIRS radiances within the analysis fields of the Weather Research and Forecast Nonhydrostatic Mesoscale Model (WRF-NMM) at the NASA Short-term Prediction Research and Transition (SPORT) Center.

  20. A Novel Method of Measuring Upwelling Radiance in the Hydrographic Sub-Hull

    NASA Astrophysics Data System (ADS)

    Rüssmeier, N.; Zielinski, O.

    2016-01-01

    In this study we present a new method useful in collecting upwelling radiance (Lu) from a platform submerged in a hydrographic sub-hull or moon pool of a research vessel. The information analyzed here was obtained during a field campaign in the Northwestern European shelf seas aboard the new research vessel SONNE. As the platform was located at the center of the ship, there is minimal effect from pitch and roll which is known to influence upwelling radiance observations. A comparison of the measurements from this platform with a free falling hyperspectral profiler was performed to determine the degree of uncertainty that results from ship shadow. For given Lu(λ) in situ data we observed ±33% intensity deviations compared to profiling measurements that can be attributed to instrument shading during moon pool installation and environmental perturbations. Furthermore Lu(λ) in situ spectra variations were observed at lower wavelengths, therefore a form fitting algorithm was adapted to receive corresponding depths with identical spectral form from Lu(z, λ) profiler casts. During an east to west transect in North Sea with a schedule speed up to 12 knots in situ radiance reflectance rrs(7, λ) measurements at 7 meter depth were performed with this novel radiometer setup. In spite of any restrictions originating from the sub-hull installation, water masses mixing zone from CDOM dominated coastal waters in the Skagerrak Strait towards the open North Sea were successfully derived thus offering an underway applicable upwelling radiance sensing not suffering from sun glint or other typical restrictions of above water radiometer installations.

  1. Influence of high altitude clouds on upper tropospheric radiance measurements.

    PubMed

    Schmidt, E O; Patterson, E M; Williams, W J

    1990-10-01

    Altitude profiles of atmospheric window radiance measured with upward-looking sensors frequently show a rapid decrease in radiance with increasing height over a narrow altitude region in the upper troposphere. This region of rapid decrease is termed a radiometric knee in the altitude profile. The top of this knee defines a radiometric tropopause with a latitudinal height dependence similar to that of the usually defined barometric tropopause. Atmospheric window (10-12-microm) radiance at these altitudes can be associated with the presence of ice particulates. Comparison of the measurements with predicted altitude profiles of atmospheric radiance from the LOWTRAN 7 atmospheric model code shows that a well-defined knee occurs when there is a cloud layer (liquid or ice) such as a subvisual cirrus cloud present. The rate and magnitude of the radiance decrease depend on the optical depth and, therefore, the water content of the layer. Atmospheric background radiance values for near horizontal (large zenith angle) viewing with upward-looking sensors can be as much as a factor of 100 lower above the knee than below it. Comparisons between calculated and observed radiance profiles were used to estimate the vertical extent, total optical depth, and water content of the clouds.

  2. A New Marine Atmospheric Emitted Radiance Interferometer (M-AERI) for Shipboard Atmospheric and Oceanic Observations

    NASA Astrophysics Data System (ADS)

    Gero, P. J.; Knuteson, R. O.; Hackel, D.; Best, F. A.; Garcia, R.; Phillips, C.; Revercomb, H. E.; Smith, W. L.; Verret, E.; Lantagne, S. M.; Roy, C. B.

    2014-12-01

    A new ship-based Fourier transform spectrometer has been developed to measure the atmospheric downwelling and reflected infrared radiance spectrum at the Earth's surface with high absolute accuracy. This instrument was designed and built by ABB (Québec, Canada) based on the heritage of the Atmospheric Emitted Radiance Interferometer (AERI) designed by the University of Wisconsin Space Science and Engineering Center (UW-SSEC) for the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program. Prior versions of the M-AERI have been operated by the University of Miami for over a decade on research ships transiting the Atlantic and Pacific in support of NASA and NOAA satellite validation. The M-AERI measures infrared radiance between 520-3020 cm-1 (3.3-19 μm), at a resolution of 1 cm-1, using two detectors cooled to cryogenic temperatures with a Stirling cycle cooler. A gold-coated rotating scene mirror allows the M-AERI to selectively view the atmospheric scene at zenith, and ocean/atmospheric scenes over a range of +/- 45° from the horizon. The AERI uses two high-emissivity blackbodies for radiometric calibration, which in conjunction with the instrument design and a suite of rigorous laboratory diagnostics, ensures the radiometric accuracy to be better than 1% (3σ) of the ambient radiance. The M-AERI radiance spectra can be used to retrieve profiles of temperature and water vapor in the troposphere, as well as measurements of trace gases, cloud properties, and ocean skin temperature. The M-AERI measurement of ocean skin temperature has a demonstrated accuracy of better than 0.1 K. The first marine deployment of the new M-AERI will be as part of the second ARM mobile facility (AMF-2) during the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) on board the NOAA Ship Ronald H. Brown in early 2015, occurring jointly with the NOAA CalWater 2 experiment. This field campaign aims to improve understanding and modeling of large-scale dynamics and cloud

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

    NASA Technical Reports Server (NTRS)

    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.; LeBlanc, S.; Schmidt, S.; Pilewskie, P.; Song, S.

    2014-01-01

    The AERONET (AErosol RObotic NETwork) ground-based suite of sunphotometers provides measurements of spectral aerosol optical depth (AOD), precipitable water and spectral sky radiance, which can be inverted to retrieve aerosol microphysical properties that are critical to assessments of aerosol-climate interactions. Because of data quality criteria and sampling constraints, there are significant limitations to the temporal and spatial coverage of AERONET data and their representativeness for global aerosol conditions.The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument, jointly developed by NASA Ames and PNNL (Pacific Northwest National Laboratory) with NASA Goddard collaboration, combines airborne sun tracking and AERONET-like sky scanning with spectroscopic detection. Being an airborne instrument, 4STAR has the potential to fill gaps in the AERONET data set. The 4STAR instrument operated successfully in the SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) experiment in Aug./Sep. 2013 aboard the NASA DC-8 and in the DoE (Department of Energy)-sponsored TCAP (Two Column Aerosol Project, July 2012 & Feb. 2013) experiment aboard the DoE G-1 aircraft. 4STAR provided direct beam measurements of hyperspectral AOD, columnar trace gas retrievals (H2O, O3, NO2), and the first ever airborne hyperspectral sky radiance scans, which can be inverted to yield the same products as AERONET ground-based observations. In this presentation, we provide an overview of the new 4STAR capabilities, with an emphasis on 26 high-quality sky radiance measurements carried out by 4STAR in SEAC4RS. We compare collocated 4STAR and AERONET sky radiances, as well as their retrievals of aerosol microphysical properties for a subset of the available case studies. We summarize the particle property and air-mass characterization studies made possible by the combined 4STAR direct beam and sky radiance

  4. Aerosol properties derived from airborne sky radiance and direct beam measurements in recent NASA and DoE field campaigns

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Flynn, C. J.; Shinozuka, Y.; Russell, P. B.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Livingston, J. M.; Schmid, B.; Dunagan, S. E.; Johnson, R. R.; LeBlanc, S. E.; Schmidt, S.; Pilewskie, P.; Song, S.

    2014-12-01

    The AERONET (AErosol RObotic NETwork) ground-based suite of sunphotometers provides measurements of spectral aerosol optical depth (AOD), precipitable water and spectral sky radiance, which can be inverted to retrieve aerosol microphysical properties that are critical to assessments of aerosol-climate interactions. Because of data quality criteria and sampling constraints, there are significant limitations to the temporal and spatial coverage of AERONET data and their representativeness for global aerosol conditions. The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument, jointly developed by NASA Ames and PNNL with NASA Goddard collaboration, combines airborne sun tracking and AERONET-like sky scanning with spectroscopic detection. Being an airborne instrument, 4STAR has the potential to fill gaps in the AERONET data set. The 4STAR instrument operated successfully in the SEAC4RS [Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys] experiment in Aug./Sep. 2013 aboard the NASA DC-8 and in the DoE [Department of Energy]-sponsored TCAP [Two Column Aerosol Project, July 2012 & Feb. 2013] experiment aboard the DoE G-1 aircraft. 4STAR provided direct beam measurements of hyperspectral AOD, columnar trace gas retrievals (H2O, O3, NO2), and the first ever airborne hyperspectral sky radiance scans, which can be inverted to yield the same products as AERONET ground-based observations. In this presentation, we provide an overview of the new 4STAR capabilities, with an emphasis on 26 high-quality sky radiance measurements carried out by 4STAR in SEAC4RS. We compare collocated 4STAR and AERONET sky radiances, as well as their retrievals of aerosol microphysical properties for a subset of the available case studies. We summarize the particle property and airmass characterization studies made possible by the combined 4STAR direct beam and sky radiance observations.

  5. Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems

    NASA Astrophysics Data System (ADS)

    Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

    2012-08-01

    This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 μm) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ("hotspot") was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm2/steradian/nm). Error analysis shows this method to be accurate to within +/- 20%, which represents a high level of accuracy for this type of measurement.

  6. Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems.

    PubMed

    Johnston, Mark D; Oliver, Bryan V; Droemer, Darryl W; Frogget, Brent; Crain, Marlon D; Maron, Yitzhak

    2012-08-01

    This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 μm) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ("hotspot") was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm(2)/steradian/nm). Error analysis shows this method to be accurate to within +∕- 20%, which represents a high level of accuracy for this type of measurement. PMID:22938275

  7. The spectral irradiance of the moon

    USGS Publications Warehouse

    Kieffer, H.H.; Stone, T.C.

    2005-01-01

    Images of the Moon at 32 wavelengths from 350 to 2450 nm have been obtained from a dedicated observatory during the bright half of each month over a period of several years. The ultimate goal is to develop a spectral radiance model of the Moon with an angular resolution and radiometric accuracy appropriate for calibration of Earth-orbiting spacecraft. An empirical model of irradiance has been developed that treats phase and libration explicitly, with absolute scale founded on the spectra of the star Vega and returned Apollo samples. A selected set of 190 standard stars are observed regularly to provide nightly extinction correction and long-term calibration of the observations. The extinction model is wavelength-coupled and based on the absorption coefficients of a number of gases and aerosols. The empirical irradiance model has the same form at each wavelength, with 18 coefficients, eight of which are constant across wavelength, for a total of 328 coefficients. Over 1000 lunar observations are fitted at each wavelength; the average residual is less than 1%. The irradiance model is actively being used in lunar calibration of several spacecraft instruments and can track sensor response changes at the 0.1% level. ?? 2005. The American Astronomical Society. All rights reserved.

  8. Time domain scattering of travelling wave radiance

    NASA Astrophysics Data System (ADS)

    Berger, Henry; Rand, Robert S.

    2002-12-01

    I present, apparently, a new description of radiative transfer problems in the time domain. It appears that for the first time a simple physical picture emerges of the underlying essence of scattered radiance when dealing with isotropic axially-symmetric scattering in nonconservative linear media as attenuated travelling waves was by analogy. The method used a new differential equation approach. Initially its accuracy in the frequency domain was demonstrated by applying it to a solved problem, where in the literature it is dealt with using the conventional 95-year-old integro-differential equation description. Confidence in the differential equation method was bolstered by showing how this new method produces the same analytical answer. The new technique converts the integro-differential equation formulation of radiative transfer into a "pure" differential equation formulation, consisting here in a mixture of ordinary and partial derivatives, and solves that. This paper analyzes the situation in the time domain using the differential equation description and again yields a travelling wave description. However, this time it is not simply by analogy that such a description is obtained. It is exact. This result of attenuated travelling waves was demonstrated in a prior paper by solving the integro-differential equation for the classic problem of axially-symmetric scalar isotropic scattering in a nonconservative linear medium. In this paper we revisit the problem, this time solving it by the differential equation method and obtain the identical result, once again confirming the method.

  9. ISCCP reduced resolution satellite radiance data

    NASA Technical Reports Server (NTRS)

    Rossow, W.

    1986-01-01

    The International Satellite Cloud Climatology Project (ISCCP) is the first active project of the World Climate Research Program. It is a multinational data collection project focused on collecting a data set that will improve the ability to predict and/or simulate the radiative effects of clouds on climate. For specified cloud parameters, the goals are to archieve values for 3-hour periods over the whole globe for 5 years at 30 km resolution. The task of collecting and processing radiance data from both geosynchronous and polar orbiting satellites began in July 1983. A diagram was shown illustrating the flow of data from the transmitting satellites to the various receiving institutions that handle it. The various stages of processing were then explained in detail, emphasizing Level B3-normalized, reformatted, reduced raw satellite data. The reduction of data by sampling is an essential step in the flow. By the time the ISCCP data reaches the Global Processing Center at Goddard Institute for Space Studies (GISS), the volume has been reduced by a factor of 1000. The Pilot Climate Data System (PLDS) will provide access to the ISCCP data set. It should prove to be one of the cleanest satellite data sets because it will have been through three filters--that of the operational agency, the Global Processing Center, and the PCDS. The ISCCP data set also includes other correlative data sets delivered in compatible format.

  10. Variations in in-flight absolute radiometric calibration. [satellite remote sensors

    NASA Technical Reports Server (NTRS)

    Slater, Philip N.

    1986-01-01

    Variations in the in-flight absolute radiometric calibration of the Coastal Zone Color Scanner and the Thematic Mapper (TM) are reviewed. At short wavelengths, the sensors show a gradual reduction in response, while in the mid-IR the TM shows oscillatory variations. One set of measurements made at White Sands, New Mexico shows anomalous results in TM bands 2 and 4. The results of a reflectance-based and a radiance-based calibration method at White Sands are described. An analysis of the radiance-based method shows the value of such measurements from helicopter altitudes for calibration.

  11. Estimation of absolute water surface temperature based on atmospherically corrected thermal infrared multispectral scanner digital data

    NASA Technical Reports Server (NTRS)

    Anderson, James E.

    1986-01-01

    Airborne remote sensing systems, as well as those on board Earth orbiting satellites, sample electromagnetic energy in discrete wavelength regions and convert the total energy sampled into data suitable for processing by digital computers. In general, however, the total amount of energy reaching a sensor system located at some distance from the target is composed not only of target related energy, but, in addition, contains a contribution originating from the atmosphere itself. Thus, some method must be devised for removing or at least minimizing the effects of the atmosphere. The LOWTRAN-6 Program was designed to estimate atmospheric transmittance and radiance for a given atmospheric path at moderate spectral resolution over an operational wavelength region from 0.25 to 28.5 microns. In order to compute the Thermal Infrared Multispectral Scanner (TIMS) digital values which were recorded in the absence of the atmosphere, the parameters derived from LOWTRAN-6 are used in a correction equation. The TIMS data were collected at 1:00 a.m. local time on November 21, 1983, over a recirculating cooling pond for a power plant in southeastern Mississippi. The TIMS data were analyzed before and after atmospheric corrections were applied using a band ratioing model to compute the absolute surface temperature of various points on the power plant cooling pond. The summarized results clearly demonstrate the desirability of applying atmospheric corrections.

  12. Plane parallel radiance transport for global illumination in vegetation

    SciTech Connect

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  15. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  16. Evaluation of Long-Term Calibrations of the AVHRR Visible Radiances

    NASA Technical Reports Server (NTRS)

    Rossow, William B.; Ferrier, Joseph

    2015-01-01

    Two systematic calibrations have been compiled for the visible radiances measured by the series of AVHRR instruments flown on the NOAA operational polar weather satellites: one by the International Satellite Cloud Climatology Project (ISCCP), anchored on NASA ER-2 underflights in the 1980s and early 1990s and covering the period 1981-2009, and one by the PATMOS-x project, anchored on comparisons to the MODIS instruments on the Aqua and Terra satellites in the 2000s and covering the period 1979-2010 (this result also includes calibration for the near-IR channels). Both methods have had to extend their anchor calibrations over a long series of instruments using different vicarious approaches, so a comparison provides an opportunity to evaluate how well this extension works by cross-checking the results at the anchor points. The basic result of this comparison is that for the ''afternoon'' series of AVHRRs, the calibrations agree to within their mutual uncertainties. However, this retrospective evaluation also shows that the representation of the time variations can be simplified. The ISCCP procedure had much more difficulty extending the calibration to the ''morning'' series of AVHRRs with the calibrations for NOAA-15 and NOAA-17 exceeding the estimated uncertainties. Given the general agreement, a new calibration for all AVHRR visible radiances (except TIROS-N, NOAA-6, NOAA-19, and MetOp-A) is proposed that is based on the average of the best linear fits to the two time records. The estimated uncertainty of these calibrations is 63% absolute (scaled radiance units).

  17. The Absolute Radiometric Calibration of Space - Sensors.

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    1987-09-01

    The need for absolute radiometric calibration of space-based sensors will continue to increase as new generations of space sensors are developed. A reflectance -based in-flight calibration procedure is used to determine the radiance reaching the entrance pupil of the sensor. This procedure uses ground-based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of five calibrations of the Landsat-5 Thematic Mapper (TM). For the 12 measurements made in TM bands 1-3, the RMS variation from the mean as a percentage of the mean is (+OR-) 1.9%, and for measurements in the IR, TM bands 4,5, and 7, the value is (+OR-) 3.4%. The RMS variation for all 23 measurements is (+OR-) 2.8%. The absolute calibration techniques were put to another test with a series of three calibration of the SPOT-1 High Resolution Visible, (HRV), sensors. The ratio, HRV-2/HRV-1, of absolute calibration coefficients compared very well with ratios of histogrammed data obtained when the cameras simultaneously imaged the same ground site. Bands PA, B1 and B3 agreed to within 3%, while band B2 showed a 7% difference. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft -based radiometer data. This procedure was applied on four dates with two different surface conditions per date. A strong correlation, R('2) = .996, was shown between reflectance values determined from satellite imagery and low-flying aircraft

  18. Aerosol, Cloud and Trace Gas Observations Derived from Airborne Hyperspectral Radiance and Direct Beam Measurements in Recent Field Campaigns

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    The AERONET (AErosol RObotic NETwork) ground-based suite of sunphotometers provides measurements of spectral aerosol optical depth (AOD), precipitable water and spectral sky radiance, which can be inverted to retrieve aerosol microphysical properties that are critical to assessments of aerosol-climate interactions. Because of data quality criteria and sampling constraints, there are significant limitations to the temporal and spatial coverage of AERONET data and their representativeness for global aerosol conditions. The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument, jointly developed by NASA Ames and PNNL with NASA Goddard collaboration, combines airborne sun tracking and AERONET-like sky scanning with spectroscopic detection. Being an airborne instrument, 4STAR has the potential to fill gaps in the AERONET data set. Dunagan et al. [2013] present results establishing the performance of the instrument, along with calibration, engineering flight test, and preliminary scientific field data. The 4STAR instrument operated successfully in the SEAC4RS [Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys] experiment in Aug./Sep. 2013 aboard the NASA DC-8 and in the DoE [Department of Energy]-sponsored TCAP [Two Column Aerosol Project, July 2012 & Feb. 2013] experiment aboard the DoE G-1 aircraft (Shinozuka et al., 2013), and acquired a wealth of data in support of mission objectives on all SEAC4RS and TCAP research flights. 4STAR provided direct beam measurements of hyperspectral AOD, columnar trace gas retrievals (H2O, O3, NO2; Segal-Rosenheimer et al., 2014), and the first ever airborne hyperspectral sky radiance scans, which can be inverted to yield the same products as AERONET ground-based observations. In addition, 4STAR measured zenith radiances underneath cloud decks for retrievals of cloud optical depth and effective diameter. In this presentation, we provide an overview of the new

  19. Urban, Forest, and Agricultural AIS Data: Fine Spectral Structure

    NASA Technical Reports Server (NTRS)

    Vanderbilt, V. C.

    1985-01-01

    Spectra acquired by the Airborne Imaging Spectrometer (AIS) near Lafayette, IN, Ely, MN, and over the Stanford University campus, CA were analyzed for fine spectral structure using two techniques: the ratio of radiance of a ground target to the radiance of a standard and also the correlation coefficient of radiances at adjacent wavelengths. The results show ramp like features in the ratios. These features are due to the biochemical composition of the leaf and to the optical scattering properties of its cuticle. The size and shape of the ramps vary with ground cover.

  20. A Principal Component Analysis Noise Filter Value-Added Procedure to Remove Uncorrelated Noise from Atmospheric Emitted Radiance Interferometer (AERI) Observations

    SciTech Connect

    C. Lo D. D. Turner R. O. Knuteson

    2006-01-31

    This technical report provide a short description of the application of the principle component analysis techniques to remove uncorrelated random noise from ground-based high spectral resolution infrared radiance observations collected by the atmospheric emitted radiance interferometers (AERIs) deployed by the Atmospheric Radiation Measurement (ARM) Program. A general overview of the technique, the input, and output datastreams of the newly generated value-added product, and the data quality checks used are provided. A more complete discussion of the theory and results is given in Turner et al. (2006).

  1. A comparative study of infrared radiance measurements by an ER-2 based radiometer and the LANDSAT 5 Thematic Mapper (TM-6)

    NASA Technical Reports Server (NTRS)

    Hammer, Philip D.; Valero, Francisco P. J.; Kinne, Stefan

    1990-01-01

    Infrared radiance measurements were acquired from a radiometer on the NASA ER-2 during a coincident LANDSAT 5 overpass on 28 Oct. 1986 as part of the FIRE Cirrus IFO in the vicinity of Lake Michigan. A comparative study is made to infer microphysical properties of the cirrus cloud field. Radiances are derived from the image by convolving the ER-2 radiometer's effective field of view along the flight path. A multistream radiative transfer model is used to account for the differences in spectral bandwidths, 10.40 to 12.50 microns for the LANDSAT band and 9.90 to 10.87 microns for the radiometer.

  2. Performance Demonstration of Miniature Phase Transition Cells in Microgravity as a Validation for their use in the Absolute Calibration of Temperature Sensors On-Orbit

    NASA Astrophysics Data System (ADS)

    Pettersen, C.; Best, F. A.; Adler, D. P.; Aguilar, D. M.; Perepezko, J. H.

    2012-12-01

    The next generation of infrared remote sensing missions, including the climate benchmark missions, will require better absolute measurement accuracy than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. As an example, instrumentation designed to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K will require high-emissivity (>0.999) calibration blackbodies requiring absolute temperature uncertainties of better than 0.045K (k=3). Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and were further refined under the NASA Instrument Incubator Program (IIP). In particular, the OARS has imbedded thermistors that can be periodically calibrated on-orbit using the melt signatures of small quantities (<0.5g) of three reference materials - mercury, water, and gallium, providing calibration from 233K to 303K. One of the many tests to determine the readiness of this technology for on-orbit application is a demonstration of performance in microgravity to be conducted on the International Space Station (ISS). This demonstration will make use of an Experiment Support Package developed by Utah State Space Dynamics Laboratory to continuously run melt cycles on miniature phase change cells containing gallium, a gallium-tin eutectic, and water. The phase change cells will be mounted in a small aluminum block along with a thermistor temperature sensor. A thermoelectric cooler will be used to change the temperature of the block. The demonstration will use the configuration of the phase transition cells developed under our NASA IIP that has been tested extensively in the laboratory under simulated mission life cycle scenarios - these included vibration, thermal soaks, and deep cycling. Melt signatures

  3. Cloud and aerosol optics by polarized micro pulse Lidar and ground based measurements of zenith radiance

    NASA Astrophysics Data System (ADS)

    Delgadillo, Rodrigo

    Clouds impact Earth's climate through cloud transmission and reflection properties. Clouds reflect approximately 15 percent of the incoming solar radiation at the top of the atmosphere. A key cloud radiative variable is cloud optical depth, which gives information about how much light is transmitted through a cloud. Historically, remote measurements of cloud optical depth have been limited to uniform overcast conditions and had low temporal and spatial resolution. We present a novel method to measure cloud optical depth for coastal regions from spectral zenith radiance measurements for optically thin clouds, which removes some of these limitations. Our measurement site is part of South Florida's Cloud-Aerosol-Rain Observatory (CAROb), located on Virginia Key, FL (6 km from Miami). This work is based on Marshak et al.'s method for finding cloud optical depth from vegetative sites that provide a strong spectral contrast between red and near infrared surface albedo. However, given the unique nature of our site, which contains water, vegetation, beach, and urban surface types, we found no such spectral contrast at those wavelength pairs. We measured albedo, with hyperspectral resolution, for different surface types around our measurement site to estimate the effective spectral albedo for the area centered on the site with a 5km radius. From this analysis, we found the best possible albedo contrast (573.9 and 673.1 nm) for our site. We tested the derived cloud optical depth from zenith radiance at these two wavelengths against a concurrently running polarized micro pulse LIDAR (MPL) and found good agreement.

  4. Temporal spectral measurements of corn and soybean crops

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    A ground-based, hand-held radiometer, configured to measure red and photographic infrared spectral radiances, was successfully used to collect in situ temporal spectral measurements of corn and soybean crops. Significant relationships were found between the radiance data and the biomass, plant height, percentage crop cover, percentage crop chlorosis, and percentage leaf loss. The results of this experiment show conclusively that hand-held radiometers can be used to collect spectral data that are highly correlated to several agronomic variables. These findings suggest approaches for agronomic research, and confirm the value of remote sensing of agricultural targets.

  5. A New Instrument for Measurement of the Solar Aureole Radiance Distribution from Unstable Platforms

    NASA Technical Reports Server (NTRS)

    Ritter, Joseph M.; Voss, Kenneth J.

    1999-01-01

    A novel imaging solar aureole radiometer, which can obtain absolute radiometric measurements of the solar aureole when operated on an unstable platform is described. A CCD array is used to image the aureole, while a neutral density occulter on a long pole blocks the direct solar radiation. This ensures accurate direction registration as the sun appears in acquired images, and the total circumsolar region is measured simultaneously. The imaging nature of this instrument along with a special triggering device permit acquisition of the circumsolar sky radiance within 7.5 degrees of the center of the solar disk, and within 1 degree of the edge of the solar disk. This innovation makes possible for the first time, reliable and accurate radiometric measurements of the solar aureole from unstable mobile platforms such as ships. This allows determination small angle atmospheric scattering. The instrument has been used in field studies of atmospheric aerosols and will be used in satellite validation and calibration campaigns.

  6. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  7. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  8. A Systematic Error Correction Method for TOVS Radiances

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Rokke, Laurie; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Treatment of systematic errors is crucial for the successful use of satellite data in a data assimilation system. Systematic errors in TOVS radiance measurements and radiative transfer calculations can be as large or larger than random instrument errors. The usual assumption in data assimilation is that observational errors are unbiased. If biases are not effectively removed prior to assimilation, the impact of satellite data will be lessened and can even be detrimental. Treatment of systematic errors is important for short-term forecast skill as well as the creation of climate data sets. A systematic error correction algorithm has been developed as part of a 1D radiance assimilation. This scheme corrects for spectroscopic errors, errors in the instrument response function, and other biases in the forward radiance calculation for TOVS. Such algorithms are often referred to as tuning of the radiances. The scheme is able to account for the complex, air-mass dependent biases that are seen in the differences between TOVS radiance observations and forward model calculations. We will show results of systematic error correction applied to the NOAA 15 Advanced TOVS as well as its predecessors. We will also discuss the ramifications of inter-instrument bias with a focus on stratospheric measurements.

  9. Future Long-term Measurements of Solar Spectral Irradiance by JPSS TSIS

    NASA Astrophysics Data System (ADS)

    Richard, E. C.; Harber, D.; Harder, J. W.; Pilewskie, P.; Brown, S.; Smith, A.; Lykke, K.

    2011-12-01

    To advance scientific understanding of how solar variability affects climate processes it is important to maintain accurate, long-term records of solar irradiance. Continuation of solar spectral irradiance (SSI) measurements is needed to characterize poorly understood wavelength-dependent climate processes. Measurement challenges in quantifying the influence of SSI variability on climate are achieving sufficient radiometric absolute accuracy and maintaining the long-term relative accuracy. The Total and Spectral Solar Irradiance Sensor (TSIS) is a dual-instrument package that will acquire solar irradiance as part of the Joint Polar Satellite System (JPSS). The TSIS Spectral Irradiance Monitor (SIM) instrument will continue the SSI measurements that began with the SORCE SIM in 2003. The TSIS SIM incorporates design and calibration improvements to better quantify long-term SSI variability. Specific improvements include the pre-launch SI-traceable calibration, the measurement precision, and the long-term relative stability needed to meet the requirements for establishing a climate record of SSI into the future. To quantify the absolute accuracy over the full spectral range, we have developed a SIM Radiometer Facility (SIMRF) utilizing the NIST Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS). This comprehensive facility includes tuneable laser light sources from the ultraviolet to the near infrared matched in radiant power to the solar spectrum and tied to a cryogenic radiometer traceable to the NIST Primary Optical Watt Radiometer (POWR). The full characterization and calibration follows a measurement equation approach at the unit-level for full validation of the end-to-end performance at the instrument-level to achieve a combined standard uncertainty of 0.25% .

  10. Comparing sources of variability in cloud-characterized HIRS radiances

    NASA Astrophysics Data System (ADS)

    Staten, P.; Kahn, B. H.; Schreier, M. M.; Heidinger, A. K.

    2014-12-01

    The difficulty of modeling and observing cloud processes continue to stymie efforts at tracking and projecting cloud behavior in a changing climate. While robust determination of the global cloud feedback remains elusive, the ~30-year radiance record from High Resolution Infrared Radiation Sounders (HIRS) and the corresponding visible imagery database may enable the constraint of individual components of the cloud feedback. Specifically, signals in region- and cloud-type-specific infrared radiances may be detectable with some significance. Using nearly simultaneous nadir cloud type information from the Clouds from AVHRR Extended (CLAVR-x) dataset, we analyze sources of variability in cloud-characterized HIRS radiances. Inter-satellite biases are large enough to hamper the determination not just of long-term trends, but also of diurnal and interannual variability. However, changes in variability, rather than the mean, may be detectable with the current state of instrumentation. Characterizing cloud variability is expected to shed light on physical climate processes.

  11. A generic fast airbreathing first stage TSTO vehicle - RADIANCE

    NASA Astrophysics Data System (ADS)

    Wagner, Alain; Dufour, Alain

    1992-12-01

    A concept is considered that reducing the delta V to be provided by the second stage reduces its mass and, hence, may allow a down scaling of the first stage despite the higher staging Mach number. The concept is based on a two-stage-to-orbit vehicle called RADIANCE that stages at Mach 12 with an airbreathing first stage and a rocket-powered second stage. A fairing is provided to avoid aerodynamic interactions between the stages. RADIANCE takes off horizontally using an integral landing gear. The booster lands horizontally on a conventional runway. After having completed its orbital mission the orbiter returns through the atmosphere for an unpowered landing to the launch base. It is noted that RADIANCE hampered by the high drag losses inherently coupled with its booster size.

  12. Modeling directional thermal radiance from a forest canopy

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    The thermal vegetation canopy radiance model of Smith et al. (1981) is extended to account for the geometrically rough structure of a forest canopy. Fourier series expansion of a canopy height profile is used to calculate improved view facts which partially account for directional variations in canopy thermal radiance transfers. Predictions from the Smith model and the modified model are compared with experimental data obtained over a deciduous forest site in Tennessee. The results show that thermal radiance from a forest canopy depends on sensor viewing angle, solar position, and the degree of geometric roughness of the canopy surface. The maximum off-nadir angle variation in the original model was 1.6 deg C, compared with 4.4 C for the modified model.

  13. Radiance limits of ceramic phosphors under high excitation fluxes

    NASA Astrophysics Data System (ADS)

    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.

  14. A 35 Year Earth Science Data Record of Gridded IR Atmospheric Radiances

    NASA Astrophysics Data System (ADS)

    Halem, M.; Chapman, D.; Nguyen, P.

    2008-12-01

    We present the generation of a 35 year Earth Science Data Record (ESDR) of gridded level 1B atmospheric radiances at a 250 km spatial resolution from sources of satellite data including the Vertical Temperature Profiler Radiometer (VTPR), High Resolution Infrared Sounder (HIRS2/3/4), and Atmospheric Infrared Sounder (AIRS). We use the MODIS long wave channels to validate the calibration of the AIRS and HIRS data. VTPR is an operational 8-spectral channel infrared sounding system with an IFOV around 55km at nadir that operated from 1972 to 1979. The HIRS/2 sensor is a 20 spectral channel instrument with an IFOV approx. 20km, that flew from 1979 to 2001 forming a 22 year record. HIRS/3, is an advanced HIRS sounder that flew on NOAA 15-17 from 1998 to the present. HIRS/4, essentially the same as HIRS/3 except for an IFOV of 10 km has flown on the ESA Met 0p A from 2006 to present. AIRS on Aqua satellite launched on May 2002 has 2374 spectral channels from 3.7 μm to 15 μm and is well calibrated as compared with MODIS channels on the same satellite. Based on the Aqua Senior Project Review of available flight fuel, power and orbital maneuvers, the assessed life span of the satellite Aqua is estimated to be 2013. No such gridded data products of just the observed IR radiances are available since the emphasis for these sensors was the inference of temperature profiles from the observations for use in weather analysis and prediction. We have developed a system, SOAR, that provides gridded radiance data for AIRS and MODIS radiances that can meet the precision and accuracy required for a Fundamental Data Record (FDR). We are exploiting the IBM Cell blade cluster (at UMBC) of 250 processors to geolocate and grid the entire data volume of AIRS and MODIS instruments employing a data intensive raycasting algorithm. The Observation Coverage (obscov) based geolocation significantly improves gridded accuracy by 1 Kelvin Brightness Temperature over most regions on Earth, when

  15. Thermal radiance observations of an active lava flow during the June 1984 eruption of Mount Etna

    SciTech Connect

    Pieri, D.C.; Glaze, L.S.; Abrams, M.J. )

    1990-10-01

    The thermal budget of an active lava flow observed on 20 June 1984 from the Southeast crater of Mount Etna, Sicily, Italy, was analyzed from data taken by the Landsat Thematic Mapper. The Thematic Mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of thermal radiation from active lava flows. Using radiance data from two reflective infrared channels, we can estimate the temperature and areas of the hottest parts of the active flow, which correspond to hot (>500{degree}C) fractures or zones at the flow surface. Using this techniques, we estimate that only 10%-20% of the total radiated thermal power output is emitted by hot zones or fractures, which constitute less than 1% of the observed surface area. Generally, it seems that only where hot fractures or zones constitute greater than about 1% of the surface area of the flow will losses from such features significantly reduce internal flow temperatures. Using our radiance observations as boundary conditions for a multicomponent thermal model of flow interior temperature, we infer that, for the parts of this flow subject to analysis, the boundary layer and flow thickness effects dominate over radiant zones in controlling the depression of core temperature.

  16. Satellite radiance bias estimation with ensemble filters: Investigations with a simple model

    NASA Astrophysics Data System (ADS)

    Hacker, J.; Auligne, T.; Anderson, J. L.; Snyder, C.

    2011-12-01

    It is well known that satellite radiance observations are contaminated with errors owing to approximations in the radiative transfer calculation and the pre-processing of the observations, representativeness error, uncertainty in the instrument spectral response function, and drift in the instrument calibration. These errors can be treated as systematic errors (biases) in the observations, but vary in time and space. Biases are typically parameterized as a series expansion consisting of two terms with parameters (β0, β1) representing the mean error and the linear bias dependence on error predictors, respectively. Those parameters, if known, appear in the forward operator for the radiances. Methods to estimate the βs on-line while assimilating satellite radiances are well established for variational data assimilation, and are somewhat less mature for ensemble data assimilation. Parameters are often estimated in a separate, but concurrent, estimation step that out of necessity assumes the correlations between the parameters and the state elements are zero. The assumption of no correlation between observation parameters and state has proven useful, but ignores the fact that correlations are non-zero in an analysis produced by increments from observations containing parameters. Correlation surviving a model advance to the next assimilation cycle then violates the assumptions in the estimation procedure. In the case of forward operators that are functions of space, as weighting functions are in radiance operators, a single bias value can introduce correlations at a scale corresponding to the spatial function. We argue that an assumption of zero correlation between parameters and state is unnecessary, allowing straightforward estimation via state augmentation in an ensemble filter. State augmentation requires non-zero correlations to update the parameters. We investigate the viability of state augmentation for observation bias parameters using the 960-variable, two

  17. Sentinel-2/MSI absolute calibration: first results

    NASA Astrophysics Data System (ADS)

    Lonjou, V.; Lachérade, S.; Fougnie, B.; Gamet, P.; Marcq, S.; Raynaud, J.-L.; Tremas, T.

    2015-10-01

    Sentinel-2 is an optical imaging mission devoted to the operational monitoring of land and coastal areas. It is developed in partnership between the European Commission and the European Space Agency. The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. It will offer a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infra-red domains). CNES is involved in the instrument commissioning in collaboration with ESA. This paper reviews all the techniques that will be used to insure an absolute calibration of the 13 spectral bands better than 5% (target 3%), and will present the first results if available. First, the nominal calibration technique, based on an on-board sun diffuser, is detailed. Then, we show how vicarious calibration methods based on acquisitions over natural targets (oceans, deserts, and Antarctica during winter) will be used to check and improve the accuracy of the absolute calibration coefficients. Finally, the verification scheme, exploiting photometer in-situ measurements over Lacrau plain, is described. A synthesis, including spectral coherence, inter-methods agreement and temporal evolution, will conclude the paper.

  18. GIFTS SM EDU Radiometric and Spectral Calibrations

    NASA Technical Reports Server (NTRS)

    Tian, J.; Reisse, R. a.; Johnson, D. G.; Gazarik, J. J.

    2007-01-01

    The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiance using a Fourier transform spectrometer (FTS). The GIFTS instrument gathers measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the processing algorithms involved in the calibration. The calibration procedures can be subdivided into three categories: the pre-calibration stage, the calibration stage, and finally, the post-calibration stage. Detailed derivations for each stage are presented in this paper.

  19. Measurement and modeling of radiance reflectance in Garda Lake

    NASA Astrophysics Data System (ADS)

    Ferratini, Silvia; Giardino, Claudia; Pierson, Donald C.; Stroembeck, Niklas; Zilioli, Eugenio

    2000-12-01

    A simple model which predicts radiance reflectance below the water surface as a function of the concentrations of chlorophyll, colored dissolved organic matter (CDOM), and suspended particulate material (SPIM) was applied in Garda lake, the largest freshwater basin in Italy and one of the most important of the European Union. The model is similar to others developed for oceanic and coastal waters predicting the radiance reflectance as a function of two inherent optical properties of water: the absorption coefficient and the backscattering coefficient. Three stations were sampled in January '98 in the southern part of Garda lake. Samples of water were collected just below the water surface to extract the optically active substances. Two underwater radiometers assembled on the same probe provided the measurement of downwelling irradiance and up welling radiance, respectively. At the same time the apparent optical properties were collected above the water volume by using a spectro radiometer. The simulated radiance reflectance spectra were compared to the ones measured and significant correlations were retrieved.

  20. The Nature of the Radiance and Polarization in Deep Oceans

    NASA Astrophysics Data System (ADS)

    You, Y.; Kattawar, G. W.; Yang, P.

    2007-12-01

    We studied the asymptotic nature of the radiance and polarization in the underwater light field in an atmosphere- ocean system. We used a vector radiative transfer code to solve for the total Stokes vector and found that the radiance of the light field becomes asymptotic more quickly than the polarization does. Our simulations imply that for a homogeneous water body described by a Petzold phase function, a single scattering albedo of ω_0 ≥ 0.8 is required to reach the asymptotic regime practically, otherwise, the radiance in the asymptotic regime becomes too small to be detected. For the asymptotic regime to be realized physically, a water body with a less anisotropic phase function and/or a larger ω0 is necessary. For a real water body described by a Case 1 water model, the asymptotic regime could be reached at wavelengths 400 nm <λ< 500 nm. The effects of Raman scattering have also been included, and it turns out that for wavelengths λ < 540 nm, the contribution from Raman scattering can be reasonably neglected in the study of the asymptotic radiance.

  1. Modeling directional thermal radiance from a forest canopy

    SciTech Connect

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

    1989-12-31

    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 view factors which partially account for the directional variations in canopy thermal radiance transfer. A modification of a previously developed thermal vegetation canopy model is presented, along with the measurements used to drive and verify the model. The evidence indicates that thermal radiance from a forest canopy depends on sensor viewing angle, solar position, and the degree of geometric roughness of the canopy surface. For the above canopy, hand-held IRT`s were not useful for investigating the nadir angle variations due to the averaging technique used. These data did show some azimuthal variations, but it is difficult to precisely interpret the trends because of the averaging employed. Comparisons were made between the ORIG and ROUGH thermal models. The data analysis and model comparisons suggest that thermal radiance from a forest canopy does depend on sensor view angle and that the variation can be partially explained by the position of the sun and the geometrically rough structure of the canopy surface.

  2. Black hole radiance, short distances, and TeV gravity.

    PubMed

    Agulló, Iván; Navarro-Salas, José; Olmo, Gonzalo J

    2006-07-28

    Using a derivation of black hole radiance in terms of two-point functions one can provide a quantitative estimate of the contribution of short distances to the spectrum. Thermality is preserved for black holes with kappalp<1. However, deviations from the Planckian spectrum can be found for mini black holes in TeV gravity scenarios, even before reaching the Planck phase.

  3. Laboratory measurements of radiance and reflectance spectra of dilute primary-treated sewage sludge

    NASA Technical Reports Server (NTRS)

    Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Gurganus, E. A.

    1977-01-01

    The feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge is evaluated. The laboratory arrangement, solar simulator, and test results from three experiments conducted in the laboratory are described. Radiance and reflectance spectra are presented for primary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled reflectance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Well-defined upwelled reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations. The spectral-reflectance values appeared to be influenced by the type of base water, but this influence was small, especially for the mixtures with low concentrations of sewage sludge.

  4. Method and program product for determining a radiance field in an optical environment

    NASA Technical Reports Server (NTRS)

    Reinersman, Phillip N. (Inventor); Carder, Kendall L. (Inventor)

    2007-01-01

    A hybrid method is presented by which Monte Carlo techniques are combined with iterative relaxation techniques to solve the Radiative Transfer Equation in arbitrary one-, two- or three-dimensional optical environments. The optical environments are first divided into contiguous regions, or elements, with Monte Carlo techniques then being employed to determine the optical response function of each type of element. The elements are combined, and the iterative relaxation techniques are used to determine simultaneously the radiance field on the boundary and throughout the interior of the modeled environment. This hybrid model is capable of providing estimates of the under-water light field needed to expedite inspection of ship hulls and port facilities. It is also capable of providing estimates of the subaerial light field for structured, absorbing or non-absorbing environments such as shadows of mountain ranges within and without absorption spectral bands such as water vapor or CO.sub.2 bands.

  5. Joint aerosol and water-leaving radiance retrieval from Airborne Multi-angle SpectroPolarimeter Imager

    NASA Astrophysics Data System (ADS)

    Xu, F.; Dubovik, O.; Zhai, P.; Kalashnikova, O. V.; Diner, D. J.

    2015-12-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) [1] has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. In step-and-stare operation mode, AirMSPI typically acquires observations of a target area at 9 view angles between ±67° off the nadir. Its spectral channels are centered at 355, 380, 445, 470*, 555, 660*, and 865* nm, where the asterisk denotes the polarimetric bands. In order to retrieve information from the AirMSPI observations, we developed a efficient and flexible retrieval code that can jointly retrieve aerosol and water leaving radiance simultaneously. The forward model employs a coupled Markov Chain (MC) [2] and adding/doubling [3] radiative transfer method which is fully linearized and integrated with a multi-patch retrieval algorithm to obtain aerosol and water leaving radiance/Chl-a information. Various constraints are imposed to improve convergence and retrieval stability. We tested the aerosol and water leaving radiance retrievals using the AirMSPI radiance and polarization measurements by comparing to the retrieved aerosol concentration, size distribution, water-leaving radiance, and chlorophyll concentration to the values reported by the USC SeaPRISM AERONET-OC site off the coast of Southern California. In addition, the MC-based retrievals of aerosol properties were compared with GRASP ([4-5]) retrievals for selected cases. The MC-based retrieval approach was then used to systematically explore the benefits of AirMSPI's ultraviolet and polarimetric channels, the use of multiple view angles, and constraints provided by inclusion of bio-optical models of the water-leaving radiance. References [1]. D. J. Diner, et al. Atmos. Meas. Tech. 6, 1717 (2013). [2]. F. Xu et al. Opt. Lett. 36, 2083 (2011). [3]. J. E. Hansen and L.D. Travis. Space Sci. Rev. 16, 527 (1974). [4]. O. Dubovik et al. Atmos. Meas. Tech., 4, 975 (2011). [5]. O. Dubovik et al. SPIE: Newsroom, DOI:10.1117/2.1201408.005558 (2014).

  6. Linking fluorescence spectroscopy to the scale of spectral sensitivity: the BAM reference fluorometer

    NASA Astrophysics Data System (ADS)

    Monte, Christian; Pilz, Walter; Resch-Genger, Ute

    2005-08-01

    Providing fluorescence and fluorescence excitation spectra traceable to the scale of spectral sensitivity (responsivity) and spectral radiance at minimized uncertainty is currently limited by two factors: The uncertainty of the available transfer standards and the uncertainty of the measurement process itself. Here the requirements on a reference fluorometer enabling measurements at minimized uncertainty, its design, the simulation and the realization are presented. The fluorometer is designed with minimized chromatic and geometrical aberrations. To realize an efficient reduction of stray light and subtractive dispersion a double monochromator design was necessary. The basic element is a so-called U-type Czerny-Turner single monochromator featuring off-axis parabolas and an entrance and exit slit virtually at the same place. Thereby spherical aberration, coma and astigmatism are effectively minimized. The here employed special double monochromator design further cancels the remaining aberrations of the single monochromator. The design of the whole spectrometer was optimized with a ray tracing program. To minimize uncertainties due to the transfer standards, the reference fluorometer is exclusively traceable to the spectral sensitivity (responsivity) scale. This enables the use of transfer standards with much smaller uncertainty. Here trap detectors are employed of common design but specially calibrated for a divergent light bundle. Based on this instrument with its achromatic design and precisely known numerical apertures the determination of absolute fluorescence spectra will be addressed.

  7. Inter-Calibration and Concatenation of Climate Quality Infrared Cloudy Radiances from Multiple Instruments

    NASA Technical Reports Server (NTRS)

    Behrangi, Ali; Aumann, Hartmut H.

    2013-01-01

    A change in climate is not likely captured from any single instrument, since no single instrument can span decades of time. Therefore, to detect signals of global climate change, observations from many instruments on different platforms have to be concatenated. This requires careful and detailed consideration of instrumental differences such as footprint size, diurnal cycle of observations, and relative biases in the spectral brightness temperatures. Furthermore, a common basic assumption is that the data quality is independent of the observed scene and therefore can be determined using clear scene data. However, as will be demonstrated, this is not necessarily a valid assumption as the globe is mostly cloudy. In this study we highlight challenges in inter-calibration and concatenation of infrared radiances from multiple instruments by focusing on the analysis of deep convective or anvil clouds. TRMM/VIRS is potentially useful instrument to make correction for observational differences in the local time and foot print sizes, and thus could be applied retroactively to vintage instruments such as AIRS, IASI, IRIS, AVHRR, and HIRS. As the first step, in this study, we investigate and discuss to what extent AIRS and VIRS agree in capturing deep cloudy radiances at the same local time. The analysis also includes comparisons with one year observations from CrIS. It was found that the instruments show calibration differences of about 1K under deep cloudy scenes that can vary as a function of land type and local time of observation. The sensitivity of footprint size, view angle, and spectral band-pass differences cannot fully explain the observed differences. The observed discrepancies can be considered as a measure of the magnitude of issues which will arise in the comparison of legacy data with current data.

  8. A new technique for retrieval of tropospheric and stratospheric ozone profiles using sky radiance measurements at multiple view angles: Application to a Brewer spectrometer

    NASA Astrophysics Data System (ADS)

    Tzortziou, Maria; Krotkov, Nickolay A.; Cede, Alexander; Herman, Jay R.; Vasilkov, Alexander

    2008-03-01

    This paper describes and applies a new technique for retrieving diurnal variability in tropospheric ozone vertical distribution using ground-based measurements of ultraviolet sky radiances. The measured radiances are obtained by a polarization-insensitive modified Brewer double spectrometer located at Goddard Space Flight Center, in Greenbelt, Maryland, USA. Results demonstrate that the Brewer angular (0-72° viewing zenith angle) and spectral (303-320 nm) measurements of sky radiance in the solar principal plane provide sufficient information to derive tropospheric ozone diurnal variability. In addition, the Brewer measurements provide stratospheric ozone vertical distributions at least twice per day near sunrise and sunset. Frequent measurements of total column ozone amounts from direct-sun observations are used as constraints in the retrieval. The vertical ozone profile resolution is shown in terms of averaging kernels to yield at least four points in the troposphere-low stratosphere, including good information in Umkehr layer 0 (0-5 km). The focus of this paper is on the derivation of stratospheric and tropospheric ozone profiles using both simulated and measured radiances. We briefly discuss the necessary modifications of the Brewer spectrometer that were used to eliminate instrumental polarization sensitivity so that accurate sky radiances can be obtained in the presence of strong Rayleigh scattering and aerosols. The results demonstrate that including a site-specific and time-dependent aerosol correction, based on Brewer direct-sun observations of aerosol optical thickness, is critical to minimize the sky radiance residuals as a function of observing angle in the optimal estimation inversion algorithm and improve the accuracy of the retrieved ozone profile.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  11. Laboratory measurements of radiance and reflectance spectra of a dilute biosolid industrial waste product

    NASA Technical Reports Server (NTRS)

    Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Gurganus, E. A.

    1979-01-01

    Experimental measurements were made of upwelled spectral signatures of various concentrations of industrial waste products mixed with water in a large water tank. Radiance and reflectance spectra for a biosolid waste product (sludge) mixed with conditioned tap water and natural river water are reported. Results of these experiments indicate that reflectance increases with increasing concentration of the sludge at practically all wavelengths for concentration of total suspended solids up to 117 ppm in conditioned tap water and 171 ppm in natural river water. Significant variations in the spectra were observed and may be useful in defining spectral characteristics for this waste product. No significant spectral differences were apparent in the reflectance spectra of the two experiments, especially for wavelengths greater than 540 nm. Reflectance values, however, were generally greater in natural river water for wavelengths greater than 540 nm. Reflectance may be considered to increase linearly with concentration of total suspended solids from 5 to 171 ppm at all wavelengths without introducing errors larger than 10 percent.

  12. Ground-based determination of atmospheric radiance for correction of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Peacock, K.

    1974-01-01

    A technique is described for estimating the atmospheric radiance observed by a downward sensor (ERTS) using ground-based measurements. A formula is obtained for the sky radiance at the time of the ERTS overpass from the radiometric measurement of the sky radiance made at a particular solar zenith angle and air mass. A graph illustrates ground-based sky radiance measurements as a function of the scattering angle for a range of solar air masses. Typical values for sky radiance at a solar zenith angle of 48 degrees are given.

  13. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  14. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  15. Generation of multi-spectral scene images under different weather conditions

    NASA Astrophysics Data System (ADS)

    Wang, Changbo; Wang, Zhangye; Wu, Yiqi; Peng, Qunsheng

    2005-10-01

    Different kinds of atmospheric media and variation of weather conditions make the generation of multi-spectral out-door scene image quite complex. In this paper, we propose a new approach to realistically generate the multi-spectral scene images under different weather conditions. We first establish the geometrical models of several special weather phenomena. The method of three-dimension cellular automata is adopted to construct the cloud, and particle system is used to model the rain. After that we calculate the radiance of different wavebands for cloud, fog, rain under different weather conditions. The radiance components, such as self-emitted radiance, reflected radiation, transmitted radiance, are calculated separately and the total radiance is thus acquired. Then, based on the spectral radiance values of cloud, rain and fog calculated by above models, we construct the scene under different weather conditions. Finally multi-spectral scene images under different weather conditions are rendered realistically. Simulation results show the potential of our approach.

  16. Radiance and polarization of light reflected from optically thick clouds.

    PubMed

    Kattawar, G W; Plass, G N

    1971-01-01

    The reflected radiance and polarization are calculated for clouds with optical thicknesses from 10 to 100. The results are presented for both the haze C and nimbostratus model. The peak in the single scattered polarization at 140 degrees for the nimbostratus model persists even with all the multiple scattering events that occur for the largest optical thicknesses considered here. The calculations are made by a Monte Carlo technique, which includes the effect of multiple scattering through all orders and a realistic anisotropic phase function for single scattering appropriate for the distribution of particle sizes in the cloud. The effect of the surface albedo is included in the calculations for the optical thickness of 10. The variation of the radiance and polarization with both the nadir and azimuthal angle is given for several solar zenith angles.

  17. Fluorescence lidar detection with shot noise and sky radiance.

    PubMed

    Rosen, D L; Gillespie, J B

    1992-07-20

    Rank annihilation-factor analysis is potentially the best method of analyzing fluorescence lidar returns because of the following capability. Rank annihilation can recognize a fluorescence signal of a component that is hidden by a large fluorescence background without a spectrum of that background. Theoretical models were developed to analyze the effectiveness of rank annihilation-factor analysis in the interpretation of lidar returns. Interferents such as background fluorescence, photon-counting noise, sky radiance, and atmospheric extinction degraded the lidar-return spectra in numerical simulations. The rank annihilation-factor analysis detection algorithm was most severely biased by the combination of photon-counting noise and sky radiance. Rank annihilation calculations were also compared with calculations done by two other detection algorithms: finding peak wavelengths and the least-squares technique. Rank annihilation is better than both techniques.

  18. Measurement of mechanoluminescence radiance of ZnS:Mn

    NASA Astrophysics Data System (ADS)

    Persits, Nili; Aharoni, Abraham; Tur, Moshe

    2015-07-01

    Mechanoluminescence (ML), the emission of light from certain crystals induced by mechanical stress, is being considered for structural health monitoring (SHM), potentially offering passive and real-time distributed detection systems. We measured the mechanoluminescent radiance of ZnS:Mn, a crystal with a relatively strong ML emission, embedded in a matrix of transparent polyurethane under different loading and fracture. This data is invaluable for the design and performance evaluation of ML sensor systems.

  19. Patterns of reflected radiance associated with geobotanical anomalies

    NASA Technical Reports Server (NTRS)

    Birnie, R. W.; Stone, T. A.; Francica, J. R.

    1985-01-01

    This paper summarizes three remote sensing experiments in which changes in remotely measured reflected radiance patterns of vegetation correlated with changes in geology. In two cases using airborne spectroradiometer data, changes in the physical properties of a uniform species correlated with zones of porphyry copper mineralization. In another case using Landsat digital data, changes were detected in the distribution and density of a number of species and combined with soil brightness data to produce a composite index useful for distinguishing lithologies.

  20. A Microwave Radiance Assimilation Study for a Tundra Snowpack

    NASA Technical Reports Server (NTRS)

    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?

  1. Infrared transfer radiometer for broadband and spectral calibration of space chambers

    NASA Astrophysics Data System (ADS)

    Jung, Timothy M.; Carter, Adriaan C.; Woods, Solomon I.; Kaplan, Simon G.; Datla, Raju U.

    2010-04-01

    The Low-Background Infrared (LBIR) facility at NIST has recently completed construction of an infrared transfer radiometer with an integrated cryogenic Fourier transform spectrometer (Cryo-FTS). This mobile system can be deployed to customer sites for broadband and spectral calibrations of space chambers and low-background HWIL testbeds. The Missile Defense Transfer Radiometer (MDXR) has many of the capabilities of a complete IR calibration facility and will replace our existing filter-based transfer radiometer (BXR) as the NIST standard detector deployed to MDA facilities. The MDXR features numerous improvements over the BXR, including: a cryogenic Fourier transform spectrometer, an on-board absolute cryogenic radiometer (ACR), an internal blackbody reference, and an integrated collimator. The Cryo-FTS can be used to measure high resolution spectra from 4 to 20 micrometers, using a Si:As blocked-impurity-band (BIB) detector. The on-board ACR can be used for self-calibration of the MDXR BIB as well as for absolute measurements of infrared sources. A set of filter wheels and a rotating polarizer within the MDXR allow for filter-based and polarization-sensitive measurements. The optical design of the MDXR makes both radiance and irradiance measurements possible and enables calibration of both divergent and collimated sources. Details of the various MDXR components will be presented as well as initial testing data on their performance.

  2. Estimation of aerosol columnar size distribution and optical thickness from the angular distribution of radiance exiting the atmosphere: simulations.

    PubMed

    Wang, M; Gordon, H R

    1995-10-20

    We report the results of simulations in which an algorithm developed for estimation of aerosol optical properties from the angular distribution of radiance exiting the top of the atmosphere over the oceans [Appl. Opt. 33, 4042 (1994)] is combined with a technique for carrying out radiative transfer computations by synthesis of the radiance produced by individual components of the aerosol-size distribution [Appl. Opt. 33, 7088 (1994)], to estimate the aerosol-size distribution by retrieval of the total aerosol optical thickness and the mixing ratios for a set of candidate component aerosol-size distributions. The simulations suggest that in situations in which the true size-refractive-index distribution can actually be synthesized from a combination of the candidate components, excellent retrievals of the aerosol optical thickness and the component mixing ratios are possible. An exception is the presence of strongly absorbing aerosols. The angular distribution of radiance in a single spectral band does not appear to contain sufficient information to separate weakly from strongly absorbing aerosols. However, when two spectral bands are used in the algorithm, retrievals in the case of strongly absorbing aerosols are improved. When pseudodata were simulated with an aerosol-size distribution that differed in functional form from the candidate components, excellent retrievals were still obtained as long as the refractive indices of the actual aerosol model and the candidate components were similar. This underscores the importance of component candidates having realistic indices of refraction in the various size ranges for application of the method. The examples presented all focus on the multiangle imaging spectroradiometer; however, the results should be as valid for data obtained by the use of high-altitude airborne sensors. PMID:21060560

  3. The absolute radiometric calibration of space-based sensors

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    A reflectance based inflight calibration procedure is used to determine the radiance reaching the entrance pupil of a sensor. This procedure uses ground based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of 5 calibrations of the LANDSAT-5 Thematic Mapper. The absolute calibration techniques were put to another test with a series of 3 calibration of the SPOT-1 High Resolution Visible sensors. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft based radiometer data. A strong correlation was shown between reflectance values determined from satellite imagery and low flying aircraft data.

  4. Atmospheric Emitted Radiance Interferometer (AERI) Archived Data at the University of Wisconsin Space Science and Engineering Center (SSEC)

    DOE Data Explorer

    The AERI instrument is an advanced version of the high spectral resolution interferometer sounder (HIS) designed and fabricated at the University of Wisconsin (Revercomb et al. 1988) to measure upwelling infrared radiances from an aircraft. The AERI is a fully automated ground-based passive infrared interferometer that measures downwelling atmospheric radiance from 3.3 - 18.2 mm (550 - 3000 cm-1) at less than 10-minute temporal resolution with a spectral resolution of one wavenumber. It has been used in DOEÆs Atmospheric Radiation Measurement (ARM) program. Much of the data available here at the Cooperative Institute for Meteorological Satellite Studies (CIMSS), an institute within the University of Wisconsin’s Space Science and Engineering Center, may also be available in the ARM Archive. On this website, data and images from six different field experiments are available, along with AERIPLUS realtime data for the Madison, Wisconsin location. Realtime data includes temperature and water vapor time-height cross sections, SKEWT diagrams, convective stability indices, and displays from a rooftop Lidar instrument. The field experiments took place in Oaklahoma and Wisconsin with the AERI prototype.

  5. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  6. 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

    NASA Astrophysics Data System (ADS)

    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

  7. An improved radiance simulation for hyperspectral infrared remote sensing of Asian dust

    NASA Astrophysics Data System (ADS)

    Han, Hyo-Jin; Sohn, Byung-Ju; Huang, Hung-Lung; Weisz, Elisabeth; Saunders, Roger; Takamura, Tamio

    2012-05-01

    The fast Radiative Transfer for Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (RTTOV) (Version 9.3) model was used for simulating the effect of East Asian dust on top of atmosphere radiances. The size distribution of Asian dust was retrieved from nine years of sky radiometer measurements at Dunhunag located in the east of Taklimakan desert of China. The default surface emissivity in RTTOV was replaced by the geographically and monthly varying data from University of Wisconsin (UW)/Cooperative Institute for Meteorological Satellite Studies (CIMSS) infrared surface spectral emissivities. For a given size distribution and surface emissivity, the effects of three refractive indices of Optical Properties of Aerosols and Clouds (OPAC) mineral aerosol, dust-like aerosol by Volz, and High Resolution Transmission (HITRAN) quartz were examined. Results indicate that the specification of surface emissivity using geographically and monthly varying UW/CIMSS data significantly improved the performance of the simulation of AIRS brightness temperature (TB) difference (BTD) between window channels, in comparison to the results from the use of default emissivity value of 0.98 in the RTTOV model, i.e., increase of the correlation coefficient from 0.1 to 0.83 for BTD between 8.9 μm and 11 μm, and from 0.31 to 0.61 for BTD between 3.8 μm and 11 μm. On the other hand, the use of Asian dust size distributions contributed to a general reduction of radiance biases over dust-sensitive window bands. A further improvement of the TB simulations has been made by considering the Volz refractive index, suggesting that hyperspectral infrared remote sensing of Asian dust can be improved using the proper optical properties of the dust and surface emissivity.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Modeling Seasonal Thermal Radiance Cycles for Change Detection at Volcanic / Geothermal Areas

    NASA Astrophysics Data System (ADS)

    Vaughan, R.; Beuttel, B. S.

    2013-12-01

    Remote sensing observations of thermal features associated with (and often preceding) volcanic activity have been used for decades to detect and monitor volcanism. However, anomalous thermal precursors to volcanic eruptions are usually only recognized retrospectively. One of the reasons for this is that precursor thermal activity is often too subtle in magnitude (spatially, temporally, or in absolute temperature) to be unambiguously detected in time to issue warnings or forecasts. Part of the reason for this is the trade-off between high spatial and high temporal resolution associated with satellite imaging systems. Thus, the goal of this work has been to develop some techniques for using high-temporal-resolution, coarse-spatial-resolution imagery to try to detect subtle thermal anomalies. To identify anomalies, background thermal activity must first be characterized. Every active, or potentially active, volcano has a unique thermal history that provides information about normal background thermal activity due to seasonal or diurnal variations. Understanding these normal variations allows recognition of anomalous activity that may be due to volcanic / hydrothermal processes - ultimately with a lead time that may be sufficient to issue eruption warnings or forecasts. Archived MODIS data, acquired ~daily from 2000 to 2012, were used to investigate seasonal thermal cycles at three volcanic areas with different types of thermal features: Mount St. Helens, which had a dacite dome-building eruption from 2004-2008; Mount Ruapehu, which has a 500-m diameter active summit crater lake; and Yellowstone, which is a large active geothermal system that has hundreds of hot springs and fumarole fields spread out over a very large area. The focus has been on using MODIS 1-km sensor radiance data in the MIR and TIR wavelength regions that are sensitive to thermal emission from features that range in temperature from hundreds of °C, down to tens of °C (below the boiling temperature

  10. Downwelling and upwelling radiance distributions sampled under cloudless conditions in Antarctica.

    PubMed

    Cordero, Raul R; Damiani, Alessandro; Ferrer, Jorge; Rayas, Juan; Jorquera, Jose; Tobar, Mario; Labbe, Fernando; Laroze, David

    2013-09-01

    We have sampled both the downwelling and upwelling radiance distributions at a camp located in the southern Ellsworth Mountains on the broad expanse of Union Glacier (700 m altitude, 79° 46' S, 82° 52' W). The measurements (at 320-440 nm wavelength range) were carried out under cloudless conditions by using a sky scanner system, during a campaign (in December, 2012) meant to assess the effects of the high albedo on the radiance distribution. The angular variations observed in both the downwelling and upwelling radiance distributions increase with the wavelength. However, these variations were considerably greater in the case of the downwelling radiance than in the case of the upwelling radiance. Indeed, we found that downwelling radiance tends to be less isotropic than the corresponding upwelling radiance. Regardless of the solar zenith angle and the wavelength, the minima of the downwelling and the upwelling radiance distributions were measured close to the zenith and to the nadir, respectively. The downwelling (upwelling) radiance increased nearly monotonically toward the horizon and peaked at zenith (nadir) angles that ranged from 75° to 90°. Comparisons with the UVSPEC radiative transfer model were used to weight up the response of the downwelling radiance distribution to changes in the albedo. PMID:24085089

  11. Efficient application of the spectrally integrated Voigt function to radiative transfer spectroscopy

    NASA Astrophysics Data System (ADS)

    Abrarov, Sanjar

    We present a new application of the spectrally integrated Voigt function (SIVF) to the radiative transfer spectroscopy that enables computation of the spectral radiance and radiance at reduced spectral resolution. Applying a technique based on the Fourier expansion of the exponential multiplier we obtain the series approximations providing high-accuracy and rapid SIVF computation. In contrast to traditional line-by-line (LBL) radiative transfer models, the proposed SIVF algorithm prevents underestimation in the absorption coefficients and, therefore, preserves the radiant energy. LBL sample computations utilizing SIVF algorithm show the advantages of the proposed methodology in terms of the accuracy and computational speed.

  12. Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1984-01-01

    The effect different wetland plant canopies have upon observed reflectance in Thematic Mapper bands is studied. The three major vegetation canopy types (broadleaf, gramineous and leafless) produce unique spectral responses for a similar quantity of live biomass. The spectral biomass estimate of a broadleaf canopy is most similar to the harvest biomass estimate when a broadleaf canopy radiance model is used. All major wetland vegetation species can be identified through TM imagery. Simple regression models are developed equating the vegetation index and the infrared index with biomass. The spectral radiance index largely agreed with harvest biomass estimates.

  13. Retrieval of red spectral albedo and bidirectional reflectance using AVHRR HRPT and GOES satellite observations of the New England region

    NASA Astrophysics Data System (ADS)

    D'Entremont, Robert P.; Schaaf, Crystal Barker; Lucht, Wolfgang; Strahler, Alan H.

    1999-03-01

    As a prototyping exercise for the moderate-resolution imaging spectroradiometer (MODIS) albedo/BRDF product, we demonstrate the retrieval of bidirectional reflectance distribution functions (BRDFs) and red spectral albedo measures for the New England region, United States, from merged AVHRR and GOES radiances at a 1 km2 (nominal) spatial scale. These data were acquired during a 25-day period in early fall 1995. The spatial pattern of BRDF retrievals shows that urban, suburban, and interurban regions exhibit directional scattering that is well modeled by the geometric optics of shadow casting. The directional reflectance of more continuous forest areas is better described by volume-scattering mechanisms. Spectral albedos are larger in urban and suburban areas than in forested regions, as might be expected from the strong absorption of leaves in the red wave band. The red spectral albedo generally increases with solar zenith angle, as has been noted in ground measurements of broadband albedo. A number of technical limitations discussed constrain the absolute accuracy of retrieved albedos presented here, although the spatial patterns of albedo and the consistency of the BRDF shapes inspire confidence. These limitations will largely be overcome with application of our algorithm to data from the MODIS and MISR instruments on the EOS AM-1 platform.

  14. New format presentation for infrared spectral emittance data. Infrared spectrometry studies, phase 5

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.; Green, A. A.

    1972-01-01

    Methods for infrared radiance measurements from geological materials were studied for airborne use over terrains with minimal vegetation. The tasks of the investigation were: (1) calculation of emittance ratios, (2) comparison of IR spectral emittance data with K-band scatterometer data over Pisgah Crater, and (3) standard infrared spectral file. Published papers reporting the research are included.

  15. Spectral emission properties of a laser-produced plasma light source in the sub-200 nm range for wafer inspection applications

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Hudgins, Duane; Abhari, Reza S.

    2015-07-01

    The spectral emission properties of a droplet-based laser-produced plasma are investigated in the vacuum ultraviolet (VUV) range. Measurements are performed with a spectrograph that operates from 30 to 180 nm with a spectral resolution of 0.1 nm. The emission spectra are recorded for different metal droplet targets, namely tin, indium, and gallium. Measurements were performed at different pressure levels of the background gas. Several characteristic emission lines are observed. The spectra are also calibrated in intensity in terms of spectral radiance to allow absolute emission power estimations from the light source in the VUV region. The presented experimental results are relevant for alternative light sources that would be needed for future wafer inspection tools. In addition, the experimental results help to determine the out-of-band radiation emission of a tin-based extreme ultraviolet (EUV) source. By tuning the type of fuel, the laser energies, and the background gas, the laser-produced plasma light source shows good capabilities to be operated as a light source that covers a spectral emission range from the EUV to the sub-200 nm range.

  16. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300-2500 nm with a spectral bandwidth of 0.5-6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  17. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300–2500 nm with a spectral bandwidth of 0.5–6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  18. Salinity, Temperature and Polarization Effects on Top of Atmosphere Radiance's for Case One Waters Using a Simple but Realistic Bio Optical Model and Full Radiative Transfer Solutions

    NASA Astrophysics Data System (ADS)

    Hollstein, A.; Fischer, J.

    2011-12-01

    Salinity, temperature and polarization have non negligible effects on water leaving radiance's for pure and case one waters. The salinity and temperature of the ocean body has an impact on the refractive index, the bulk scattering coefficient and the absorption coefficient of the sea water. In addition these are specially dependent and we use the channels of the satellite ocean color instruments MERIS and the upcoming OLCI instrument to discuss the effects. The changes in top of atmosphere radiance's caused by changes in temperature and salinity are spectral dependent and depend on viewing geometry also. For the clearest waters these effects are in the order of two to six percent and can be reduced to the order of one percent by increased chlorophyll concentration. We present our new simple but realistic bio optical model used in our full polarized radiative transfer model. The model relates the oceanic chlorophyll concentration to scattering matrices and absorption coefficients for the chlorophyll and colored dissolved organic matter. We discuss the model's advantages and limitations and its relation to other models. Polarization has impact in this scheme if it is neglected in the radiative transfer and that the polarization parameters and the degree of polarization caries information about the state of the ocean. The effects of neglecting polarization depend strongly on direction and wavelength and can reach values of six percent. Hence salinity, temperature and polarization can have impacts of similar magnitude on top of atmosphere radiance's. The degree of polarization is sensitive to chlorophyll concentration and salinity but may also be an issue for radiance sensors showing probably unknown dependencies with respect to polarization. We can conclude that all three parameters can lead to non negligible effects on top of atmosphere radiance's and hence ocean color retrieval schemes.

  19. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  20. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  1. The thermal infrared radiance properties of dust aerosol over ocean

    NASA Astrophysics Data System (ADS)

    Hao, Zengzhou; Pan, Delu; Tu, Qianguang; Gong, Fang; Chen, Jianyu

    2015-10-01

    Asian dust storms, which can long-range transport to ocean, often occur on spring. The present of Asian dust aerosols over ocean makes some difficult for other studies, such as cloud detection, and also take some advantage for ocean, such as take nutrition into the ocean by dry or wet deposition. Therefore, it is important to study the dust aerosol and retrieve the properties of dust from satellite observations that is mainly from the thermal infrared radiance. In this paper, the thermal infrared radiance properties of dust aerosol over ocean are analyzed from MODIS and MTSAT2 observations and Streamer model simulations. By analyzing some line samples and a series of dust aerosol region, it shows that the dust aerosol brightness temperature at 12μm (BT12) is always greater than BT11 and BT8.5, and BT8.5 is general greater than BT11. The brightness temperature different between 11μm and 12μm (BTD11-12) increases with the dust intensity. And the BTD11-12 will become positive when the atmospheric relative humidity is greater than 70%. The BTD11-12 increases gradually with the surface temperature while the effect on BTD11-12 of dust layer temperature is not evident. Those are caused by the transmission of the dust aerosol is different at the two thermal infrared channels. During daytime, dust infrared brightness temperature at mid-infrared bands should reduce the visual radiance, which takes about 25K or less. In general, BT3.7 is greater than BT11 for dust aerosol. Those results are helpful to monitor or retrieve dust aerosol physical properties over ocean from satellite.

  2. Miniature High Stability High Temperature Space Rated Blackbody Radiance Source

    NASA Astrophysics Data System (ADS)

    Jones, J. A.; Beswick, A. G.

    1987-09-01

    This paper presents the design and test performance of a conical cavity type blackbody radiance source that will meet the requirements of the Halogen Occultation Experiment (HALOE) on the NASA Upper Atmospheric Research Satellite program (UARS). Since a radiance source meeting the requirements of this experiment was unavailable in the commercial market, a development effort was undertaken by the HALOE Project. The blackbody radiance source operates in vacuum at 1300 K + 0.5 K over any 15-minute interval, uses less than 7.5 watts of power, maintains a 49°C outer case temperature, and fits within the 2.5 x 2.5 x 3.0 inch envelope allocated inside the HALOE instrument. Also, the unit operates in air, during ground testing of the HALOE instrument, where it uses 17 watts of power with an outer case temperature of 66°C. The thrust of this design effort was to minimize the heat losses, in order to keep the power usage under 7.5 watts, and to minimize the amount of silica in the materials. Silica in the presence of the platinum heater winding used in this design would cause the platinum to erode, changing the operating temperature set-point. The design required the development of fabrication techniques which would provide very small, close tolerance parts from extremely difficult-to-machine materials. Also, a space rated ceramic core and unique, low thermal conductance, ceramic-to-metal joint was developed, tested and incorporated in this design. The completed flight qualification hardware has undergone performance, environmental and life testing. The design configuration and test results are discussed in detail in this paper.

  3. Active fire detection using a peat fire radiance model

    NASA Astrophysics Data System (ADS)

    Kushida, K.; Honma, T.; Kaku, K.; Fukuda, M.

    2011-12-01

    The fire fractional area and radiances at 4 and 11 μm of active fires in Indonesia were estimated using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images. Based on these fire information, a stochastic fire model was used for evaluating two fire detection algorithms of Moderate Resolution Imaging Spectroradiometer (MODIS). One is single-image stochastic fire detection, and the other is multitemporal stochastic fire detection (Kushida, 2010 - IEEE Geosci. Remote Sens. Lett.). The average fire fractional area per one 1 km2 ×1 km2 pixel was 1.7%; this value corresponds to 32% of that of Siberian and Mongolian boreal forest fires. The average radiances at 4 and 11 μm of active fires were 7.2 W/(m2.sr.μm) and 11.1 W/(m2.sr.μm); these values correspond to 47% and 91% of those of Siberian and Mongolian boreal forest fires, respectively. In order to get false alarms less than 20 points per 106 km2 area, for the Siberian and Mongolian boreal forest fires, omission errors (OE) of 50-60% and about 40% were expected for the detections by using the single and multitemporal images, respectively. For Indonesian peat fires, OE of 80-90% was expected for the detections by using the single images. For the peat-fire detections by using the multitemporal images, OE of about 40% was expected, provided that the background radiances were estimated from past multitemporal images with less than the standard deviation of 1K. The analyses indicated that it was difficult to obtain sufficient active-fire information of Indonesian peat fires from single MODIS images for the fire fighting, and that the use of the multitemporal images was important.

  4. Spectral ratio method for measuring emissivity

    USGS Publications Warehouse

    Watson, K.

    1992-01-01

    The spectral ratio method is based on the concept that although the spectral radiances are very sensitive to small changes in temperature the ratios are not. Only an approximate estimate of temperature is required thus, for example, we can determine the emissivity ratio to an accuracy of 1% with a temperature estimate that is only accurate to 12.5 K. Selecting the maximum value of the channel brightness temperatures is an unbiased estimate. Laboratory and field spectral data are easily converted into spectral ratio plots. The ratio method is limited by system signal:noise and spectral band-width. The images can appear quite noisy because ratios enhance high frequencies and may require spatial filtering. Atmospheric effects tend to rescale the ratios and require using an atmospheric model or a calibration site. ?? 1992.

  5. Stratospheric thickness determined directly from satellite radiance measurements.

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.; Gelman, M. E.

    1972-01-01

    Discussion of the use of satellite radiance data for determining the thickness of deep stratospheric layers. Empirical regression equations are shown to provide better estimates of stratospheric thickness than do mean weighted temperatures obtained from the Planck equation. The best regression equations were found for thick layers emitting a substantial portion of the CO2-band infrared radiation measured by satellites. By adding the layer thickness to the observed height field for the lower boundary, it is possible to construct constant-pressure maps at very high altitudes.

  6. Mesoscale Gravity Wave Variances from AMSU-A Radiances

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.

    2004-01-01

    A variance analysis technique is developed here to extract gravity wave (GW) induced temperature fluctuations from NOAA AMSU-A (Advanced Microwave Sounding Unit-A) radiance measurements. By carefully removing the instrument/measurement noise, the algorithm can produce reliable GW variances with the minimum detectable value as small as 0.1 K2. Preliminary analyses with AMSU-A data show GW variance maps in the stratosphere have very similar distributions to those found with the UARS MLS (Upper Atmosphere Research Satellite Microwave Limb Sounder). However, the AMSU-A offers better horizontal and temporal resolution for observing regional GW variability, such as activity over sub-Antarctic islands.

  7. Characterization of the oceanic light field within the photic zone: Fluctuations of downward irradiance and asymmetry of horizontal radiance

    NASA Astrophysics Data System (ADS)

    Gassmann, Ewa

    Two distinctive features of underwater light field in the upper ocean were examined: the wave-induced high-frequency light fluctuations within the near-surface layer under sunny skies, and the asymmetry of horizontal radiance within the photic layer of the ocean. To characterize the spatiotemporal statistical properties of the wave-induced light fluctuations, measurements of downward plane irradiance were made with novel instrumentation within the top 10 m layer of the ocean at depths as shallow as 10 cm under sunny skies, different solar zenith angles, and weak to moderate wind speeds. It was found that the maximum intensity of light fluctuations occurs at depths as shallow as 20 cm under the most favorable conditions for wave focusing, which correspond to high sun in a clear sky with weak wind. The strong frequency dependence of light fluctuations at shallow near-surface depths indicates dominant frequency range of 1 -- 3 Hz under favorable conditions that shifts toward lower frequencies with increasing depth. The light fluctuations were found to be spatially correlated over horizontal distances varying from few up to 10 -- 20 cm at temporal scales of 0.3 -- 1 sec (at the dominant frequency of 1 -- 3 Hz). The distance of correlation showed a tendency to increase with increasing depth, solar zenith angle, and wind speed. The observed variations in spatiotemporal statistical properties of underwater light fluctuations with depth and environmental conditions are driven largely by weakening of sunlight focusing which is associated with light scattering within the water column, in the atmosphere and at the air-sea interface. To investigate the underwater horizontal radiance field, measurements of horizontal spectral radiance in two opposite directions (solar and anti-solar azimuths) within the solar principal plane were made within the photic layer of the open ocean. The ratio of these two horizontal radiances represents the asymmetry of horizontal radiance field. In

  8. The Effect of Cirrus Clouds on 8-13-micro Infrared Sky Radiance.

    PubMed

    Hall, F F

    1968-05-01

    An experimental investigation of ir sky radiance and radiance fluctuations in the 8-13-micro atmospheric window is reported. Measurements were made with ground-based, filtered bolometer detector radiometers under clear sky and cirrus overcast conditions. Sky radiance was measured very close to the limb of the sun to permit detection of the solar aureole caused by forward scattering by cirrus ice crystals. Polarized sky radiance was found at large zenith angles and is attributed to scattering by cirrus of thermal emission from the earth. The radiance due to tropospheric water vapor is predicted by means of a radiation chart. Measurements of clear sky radiance exceeded that predicted by the chart in all but one case. The radiance of visible cirrus greatly exceeds the radiation chart prediction. Diffraction about cirrus cloud particles leads to a prediction of a solar aureole of a size that corresponds to the measured aureole. It is concluded that even a cirrus haze, which is quite difficult for an unaided, observer to detect, can cause an excess zenith radiance of 0.1 mW cm(-2)sr(-1), which increases to twice this value at a zenith angle of 60 degrees . Even thin but visible cirrus clouds can easily produce an excess zenith radiance of 1 mW cm(-2)sr(-1), which increases by a factor 1.4 at a zenith angle of 60 degrees .

  9. Glue Film Thickness Measurements by Spectral Reflectance

    SciTech Connect

    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.

  10. The assimilation of hyperspectral satellite radiances in Global Numerical Weather Prediction

    NASA Astrophysics Data System (ADS)

    Jung, James Alan

    Hyperspectral infrared radiance data present opportunities for significant improvements in data assimilation and Numerical Weather Prediction (NWP). The increase in spectral resolution available from the Atmospheric Infrared Sounder (AIRS) sensor, for example, will make it possible to improve the accuracy of temperature and moisture fields. Improved accuracy of the NWP analyses and forecasts should result. In this thesis we incorporate these hyperspectral data, using new assimilation methods, into the National Centers for Environmental Prediction's (NCEP) operational Global Data Assimilation System/Global Forecast System (GDAS/GFS) and investigate their impact on the weather analysis and forecasts. The spatial and spectral resolution of AIRS data used by NWP centers was initially based on theoretical calculations. Synthetic data were used to determine channel selection and spatial density for real time data assimilation. Several problems were previously not fully addressed. These areas include: cloud contamination, surface related issues, dust, and temperature inversions. In this study, several improvements were made to the methods used for assimilation. Spatial resolution was increased to examine every field of view, instead of one in nine or eighteen fields of view. Improved selection criteria were developed to find the best profile for assimilation from a larger sample. New cloud and inversion tests were used to help identify the best profiles to be assimilated in the analysis. The spectral resolution was also increased from 152 to 251 channels. The channels added were mainly near the surface, in the water vapor absorption band, and in the shortwave region. The GFS was run at or near operational resolution and contained all observations available to the operational system. For each experiment the operational version of the GFS was used during that time. The use of full spatial and enhanced spectral resolution data resulted in the first demonstration of

  11. Enhancing skin radiance through the use of effect pigments.

    PubMed

    Funk, David; Kovarovic, Brandon; Uzunian, Gabriel; Litchauer, Jill; Daley-Bowles, Tricia; Hubschmitt, Amber

    2015-01-01

    In this study, the radiance contribution from formulating various pearlescent effect pigments into a skin cream was modeled using gloss map histograms created from digital photographs of clinical panelists. CIELab color data from the various pearlescent effect pigments applied to simulated skin tone drawdown cards was first collected to screen experimental candidates and to help select the concentration of pigment used in the formula. Optical microscopy was used to develop a simple coverage model to control for the differences in particle size and density of the effect pigments. In the subsequent in vivo study, panelists applied a weighed amount of cream containing various pearlescent effect pigments to the face and high-resolution digital photography images were collected on each panelist for image analysis. Gloss map histograms were developed through the software analysis of gray-scale images, which were used to describe the gloss, whiteness, and/or radiance contribution of each pearlescent effect pigment. The resulting gloss map histograms shared identifiable characteristics useful for statistical analysis and description. This methodology could serve as a novel way to investigate and describe the visual impact and benefit of formulating effect pigments in cosmetic creams intended for application on the skin.

  12. Imaging spectrometer measurement of water vapor in the 400 to 2500 nm spectral region

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Roberts, Dar A.; Conel, James E.; Dozier, Jeff

    1995-01-01

    The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) measures the total upwelling spectral radiance from 400 to 2500 nm sampled at 10 nm intervals. The instrument acquires spectral data at an altitude of 20 km above sea level, as images of 11 by up to 100 km at 17x17 meter spatial sampling. We have developed a nonlinear spectral fitting algorithm coupled with a radiative transfer code to derive the total path water vapor from the spectrum, measured for each spatial element in an AVIRIS image. The algorithm compensates for variation in the surface spectral reflectance and atmospheric aerosols. It uses water vapor absorption bands centered at 940 nm, 1040 nm, and 1380 nm. We analyze data sets with water vapor abundances ranging from 1 to 40 perceptible millimeters. In one data set, the total path water vapor varies from 7 to 21 mm over a distance of less than 10 km. We have analyzed a time series of five images acquired at 12 minute intervals; these show spatially heterogeneous changes of advocated water vapor of 25 percent over 1 hour. The algorithm determines water vapor for images with a range of ground covers, including bare rock and soil, sparse to dense vegetation, snow and ice, open water, and clouds. The precision of the water vapor determination approaches one percent. However, the precision is sensitive to the absolute abundance and the absorption strength of the atmospheric water vapor band analyzed. We have evaluated the accuracy of the algorithm by comparing several surface-based determinations of water vapor at the time of the AVIRIS data acquisition. The agreement between the AVIRIS measured water vapor and the in situ surface radiometer and surface interferometer measured water vapor is 5 to 10 percent.

  13. High spectral resolution measurements for the ARM Program

    SciTech Connect

    Revercomb, H.E.

    1992-05-22

    This report focuses on the design and fabrication of high spectral resolution FTIR (Fourier Transform Infrared) instrumentation for the CART sites of the Atmospheric Radiation Measurement (ARM) Program. The ultimate objective of this grant is to develop three different types of instruments, named the AERI, AERI-X, and SORT. The Atmospheric Emitted Radiance Interferometer (AERI) is the simplest. It will be available for early deployment at the first ARM site and will be deployable at several locations in the extended network to give horizontal coverage. The AERI will be an 0.5 cm{sup {minus}1} resolution instrument, which measures accurately calibrated radiance spectra for radiation studies and for remote sensing of atmospheric state variables. The AERI-X and the SORTI are higher spectral resolution instruments for obtaining the highest practical resolution for spectroscopy at the ARM central sites. The AERI-X, like the AERI will measure atmospheric emitted radiance, but with resolutions as high as 0.1 cm{sup {minus}1}. The Solar Radiance Transmission Interferometer will measure the total transmission of the atmosphere by tracking the sun through changes in atmospheric air mass. The large solar signal makes it practical for this instrument to offer the ultimate in spectral resolution, about 0.002 cm{sup {minus}1}.

  14. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.

  15. Columnar Aerosol Single-Scattering Albedo and Phase Function Retrieved from Sky Radiance Over the Ocean: Measurements of African Dust

    NASA Technical Reports Server (NTRS)

    Cattrall, Christopher; Carder, Kendall L.; Gordon, Howard R.

    2001-01-01

    The single-scattering albedo and phase function of African mineral dust are retrieved from ground-based measurements of sky radiance collected in the Florida Keys. The retrieval algorithm employs the radiative transfer equation to solve by iteration for these two properties which best reproduce the observed sky radiance using an assumed aerosol vertical structure and measured aerosol optical depth. Thus, no assumptions regarding particle size, shape, or composition are required. The single-scattering albedo, presented at fourteen wavelengths between 380 and 870 nm, displays a spectral shape expected of iron-bearing minerals but is much higher than current dust models allow. This indicates the absorption of light by mineral dust is significantly overestimated in climate studies. Uncertainty in the retrieved albedo is less than 0.02 due to the small uncertainty in the solar-reflectance-based calibration (12.2%) method employed. The phase function retrieved at 860 nm is very robust under simulations of expected experimental errors, indicating retrieved phase functions at this wavelength may be confidently used to describe aerosol scattering characteristics. The phase function retrieved at 443 nm is very sensitive to expected experimental errors and should not be used to describe aerosol scattering. Radiative forcing by aerosol is the greatest source of uncertainty in current climate models. These results will help reduce uncertainty in the absorption of light by mineral dust. Assessment of the radiative impact of aerosol species is a key component to NASA's Earth System Enterprise.

  16. On the Estimation of Photometric Spectral Types

    NASA Astrophysics Data System (ADS)

    Oblak, E.; Chareton, M.

    1981-09-01

    We have estimated a photometric spectral type based on indices of the uvbyβ photometry for the normal stars of the Hauck and Mermilliod (1975) compilation. In this sample 1563 stars have no MK spectral types for 440 stars it is difficult or impossible to estimate a spectral type from the photometry for 436 stars having an estimated photometric spectral type we have found an MK spectral type on the literature which allowed a comparative study. We give the absolute magnitudes for the MK and photometric spectral types.

  17. In-flight absolute calibration of the CBERS-2 CCD sensor data.

    PubMed

    Ponzoni, Flávio J; Zullo Junior, Jurandir; Lamparelli, Rubens A C

    2008-06-01

    Since the first images of the sensors on board of CBERS-2 (China-Brazil Earth Resources Satellite) satellite were made available by the National Institute for Space Research (INPE), users have asked information about the conversion of image digital numbers to physical data (radiance or reflectance). This paper describes the main steps that were carried out to calculate the in-flight absolute calibration coefficients for CBERS-2 CCD level 2 (radiometric and geometric correction) images considering the reflectance-based method. Remarks about the preliminary evaluation of these coefficients application are also presented.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Asymptotic radiance and polarization in optically thick media: ocean and clouds.

    PubMed

    Kattawar, G W; Plass, G N

    1976-12-01

    Deep in a homogeneous medium that both scatters and absorbs photons, such as a cloud, the ocean, or a thick planetary atmosphere, the radiance decreases exponentially with depth, while the angular dependence of the radiance and polarization is independent of depth. In this diffusion region, the asymptotic radiance and polarization are also independent of the incident distribution of radiation at the upper surface of the medium. An exact expression is derived for the asymptotic radiance and polarization for Rayleigh scattering. The approximate expression for the asymptotic radiance derived from the scalar theory is shown to be in error by as much as 16.4%. An exact expression is also derived for the relation between the diffusion exponent k and the single scattering albedo. A method is developed for the numerical calculation of the asymptotic radiance and polarization for any scattering matrix. Results are given for scattering from the haze L and cloud C3 distributions for a wide range of single scattering albedos. When the absorption is large, the polarization in the diffusion region approaches the values obtained for single scattered photons, while the radiance approaches the value calculated from the expression: phase function divided by (1 + kmicro), where micro is the cosine of the zenith angle. The asymptotic distribution of the radiation is of interest since it depends only on the inherent optical properties of the medium. It is, however, difficult to observe when the absorption is large because of the very low radiance values in the diffusion region.

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

    EPA Science Inventory

    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...

  1. Mars Exploration Rover Pancam Observations of Spectral Diversity in Fine-Grained Materials at the Gusev and Meridiani Landing Sites

    NASA Astrophysics Data System (ADS)

    Bell, James F.; Fraeman, A.; Grossman, L. I.; Athena Science Team

    2006-09-01

    During 900 sols on Mars, the Mars Exploration Rover Spirit and Opportunity Pancam instruments have acquired more than 1500 "13 filter" single-pointing multispectral image cubes of targets of interest along each rover's traverse. These image cubes sample 11 distinct narrowband wavelengths between 432 nm and 1009 nm, and have been calibrated to absolute radiance and I/F using pre-flight calibration data and in-flight observations of the Pancam calibration target. The data were acquired in order to help constrain the iron-bearing mineralogy of martian materials, to help choose targets for in situ chemical and mineralogic measurements, and to provide context and visible to near-IR color data to augment chemical, Microscopic Imager, and Mini-TES observations. Our analysis here focuses on the Pancam spectral properties of the fine-grained components: mostly soil and dust materials but also sand, cobbles, spherules, RAT grindings, and some rock/outcrop surfaces. We analyzed about 900 and 600 Pancam image cubes acquired through Spirit sol 831 and Opportunity sol 754, respectively. Distinctive potential spectral units were identified in a subset of these cubes first through visual inspection of false-color composite images. Spectra from these units were then examined in detail and average unit spectra were extracted using manually defined regions of interest. Our final data set consisted of about 1200 spectra from Spirit and 350 spectra from Opportunity. These were then grouped into spectral classes using a combination of band parameterizations, spectral similarity algorithms, and visual inspection. Our 20 current Spirit classes include 4 bright, 3 dark, and 8 white/yellow soil classes, 4 rock/rock dust classes, and a sky class. Our 19 current Opportunity classes include 7 for soils, 3 for spherules, 3 for small rocks/cobbles, 3 for rocks/rock dust, and 3 sky/other classes. Here we show examples of these spectral classes and discuss their distribution and mineralogic

  2. Model Calculations of Solar Spectral Irradiance in the 3.7 Micron Band for Earth Remote Sensing Applications

    NASA Technical Reports Server (NTRS)

    Platnick, Steven; Fontenla, Juan M.

    2006-01-01

    Since the launch of the first Advanced Very High Resolution Radiometer (AVHRR) instrument aboard TIROS-N, measurements in the 3.7 micron atmospheric window have been exploited for use in cloud detection and screening, cloud thermodynamic phase and surface snow/ice discrimination, and quantitative cloud particle size retrievals. The utility of the band has led to the incorporation of similar channels on a number of existing satellite imagers and future operational imagers. Daytime observations in the band include both reflected solar and thermal emission energy. Since 3.7 micron channels are calibrated to a radiance scale (via onboard blackbodies), knowledge of the top-of-atmosphere solar irradiance in the spectral region is required to infer reflectance. Despite the ubiquity of 3.7 micron channels, absolute solar spectral irradiance data comes from either a single measurement campaign (Thekaekara et al. 1969) or synthetic spectra. In this study, we compare historical 3.7 micron band spectral irradiance data sets with the recent semi-empirical solar model of the quiet-Sun by Fontenla et al. (2006). The model has expected uncertainties of about 2 % in the 3.7 pm spectral region. We find that channel-averaged spectral irradiances using the observations reported by Thekaekara et al. are 3.2-4.1% greater than those derived from the Fontenla et al. model for MODIS and AVHRR instrument bandpasses; the Kurucz spectrum (1995) as included in the MODTRAN4 distribution, gives channel-averaged irradiances 1.2-1.5 % smaller than the Fontenla model. For the MODIS instrument, these solar irradiance uncertainties result in cloud microphysical retrievals uncertainties comparable with other fundamental reflectance error sources.

  3. The effect of variations in relative spectral response on the retrieval of land surface parameters from multiple sources of remotely sensed imagery

    USGS Publications Warehouse

    Meyer, D.J.; Chander, G.

    2008-01-01

    Airborne Visible Infrared Imaging Spectrometer (AVIRIS) images , collected over Sioux Falls, South Dakota, were used to quantify the effect of spectral response on different surface materials and to develop spectral "figures-of-merit" for spectral responses covering similar, but not identical spectral bands. In this simulation, AVIRIS images were converted to radiance, then spectrally resampled to six wavelength bands commonly used for terrestrial observation. Preliminary results indicate that differences between the simulations can be attributed to variations in surface reflectance within spectral bands, and suggest influences due to water vapor absorption. Radiance simulated from the spectrally narrow Moderate Resolution Imaging Spectroradiometer (MODIS) Relative Spectral Responses (RSR) was generally higher than that using the broader Enhanced Thematic Mapper Plus (ETM+) RSRs over most targets encountered over the test area. This is consistent with many MODIS bands being biased toward shorter wavelengths compared to corresponding ETM+ bands when viewing targets whose radiance decreases with wavelength. In some cases the higher radiance values appeared to occur where the MODIS RSR is better situated over peak reflected wavelengths. Simulation differences between MODIS & ETM+ bands in the near-infrared indicated higher MODIS radiance values that suggest the influence of water vapor absorption at 820 nanometers. This result agreed with water vapor values retrieved from the AVIRIS images themselves at around 2.7 cm precipitable water, and measurements made at a nearby AERONET node at around 2.8cm during the AVIRIS overflight ?? 2007 IEEE.

  4. Determination of the in-flight spectral calibration of AVIRIS using atmospheric absorption features

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    1995-01-01

    Spectral calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) as data are acquired in flight is essential to quantitative analysis of the measured upwelling spectral radiance. In each spectrum measured by AVIRIS in flight, there are numerous atmospheric gas absorption bands that drive this requirement for accurate spectral calibration. If the surface and atmospheric properties are measured independently, these atmospheric absorption bands may be used to deduce the in-flight spectral calibration of an imaging spectrometer. Both the surface and atmospheric characteristics were measured for a calibration target during an in-flight calibration experiment held at Lunar Lake, Nevada on April 5, 1994. This paper uses upwelling spectral radiance predicted for the calibration target with the MODTRAN radiative transfer code to validate the spectral calibration of AVIRIS in flight.

  5. [Spectral radiometric calibration research of Quick Bird digital image].

    PubMed

    Zhang, Guo-Kun; Chen, Chun; Xing, Fu; Zhang, Hong-Yan; Zhao, Yun-Sheng

    2008-03-01

    The present article uses the basic operation of the digital remote image radiometric calibration of the Quickbird with high distinguishing rate, including the physical attribute and the mathematical basement of digital images, the annotation as well as the format of image data. The study makes use of information of spectral radiance from the ground-atmosphere system, which is recorded by the digital remote image of Quick Bird in Honghe area. This dissertation offered the calculation means of radiometric calibration, and changed the pixel digital number into band-integrated radiance. Then, the spectral radiance was calculated. After the radiometric calibration, the Quick Bird image showed the quantitative information of spectral feature from various ground items. Only through the calibration can the Quick Bird image be quantitatively compared and analyzed with other remote sensor images. Thus, the inversion image has the value of application. The significance consists in offering important basic condition for the image amalgamation and better disposal of the special inforation pick-up. This effort also offered spectral information of the ground items for the inversion of the remote image. Therefore, the authors can combine the research of the spectral character of ground items with the establishment of the remote application model in order to quantitatively analyze the ground items.

  6. Feasibility of quasi-random band model in evaluating atmospheric radiance

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Mirakhur, N.

    1980-01-01

    The use of the quasi-random band model in evaluating upwelling atmospheric radiation is investigated. The spectral transmittance and total band adsorptance are evaluated for selected molecular bands by using the line by line model, quasi-random band model, exponential sum fit method, and empirical correlations, and these are compared with the available experimental results. The atmospheric transmittance and upwelling radiance were calculated by using the line by line and quasi random band models and were compared with the results of an existing program called LOWTRAN. The results obtained by the exponential sum fit and empirical relations were not in good agreement with experimental results and their use cannot be justified for atmospheric studies. The line by line model was found to be the best model for atmospheric applications, but it is not practical because of high computational costs. The results of the quasi random band model compare well with the line by line and experimental results. The use of the quasi random band model is recommended for evaluation of the atmospheric radiation.

  7. Direct determination of the thickness of stratospheric layers from single-channel satellite radiance measurements.

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.; Gelman, M. E.

    1972-01-01

    The direct use of measured radiances for determining the thickness of stratospheric layers is investigated. Layers based at 100-10 mb, with upper boundaries at 10-0.5 mb, are investigated using a carefully selected family of stratospheric temperature profiles and computed radiances. On the basis of physical reasoning, a high correlation of thickness with radiance is anticipated for deep layers, such as the 100- to 2-mb layer (from about 15 to 43 km), that emit a substantial part of the infrared energy reaching a satellite radiometer in a particular channel. Empirical regression curves relating thickness and radiance are developed and are compared with blackbody curves obtained by substituting the blackbody temperature in the hydrostatic equation. Maximum thickness-radiance correlation is found, for each infrared channel, for the layer having the best agreement of empirical and blackbody curves.

  8. NIMS Radiance Point Spectra of Gaspra V1.0

    NASA Astrophysics Data System (ADS)

    Granahan, J. C.

    2014-10-01

    This data volume contains radiometrically corrected point spectra of asteroid 951 as acquired by the Galileo spacecraft Near Infrared Mapping Spectrometer (NIMS) on October 29, 1991. They record the spectra collected as the Galileo spacecraft approached the target asteroid. These data are products of the calibration of the raw data number files gap015tn.qub, gap035tn.qub, gap036tn.qub, gap037tn.qub, and gap038tn.qub (DATA SET ID ='GO-A-NIMS-3 TUBE-V1.0') with calibration factors acquired during the first Earth/Moon encounter of the Galileo mission. These raw data .qub files are archived in the Imaging Node of the NASA Planetary Data System (PDS). The calibrated spectra consist of radiance measurements for wavelengths between 0.7 - 5.2 micrometers.

  9. Determination of Saharan dust radiance and chlorophyll from CZCS imagery

    NASA Technical Reports Server (NTRS)

    Carder, K. L.; Costello, D. K.; Gregg, W. W.; Haddad, K.; Prospero, J. M.

    1991-01-01

    This paper presents an algorithm, called the two-component method, to distinguish between two aerosol types in a remote color-scanner image and to determine their relative concentrations by observing the radiance contribution from each aerosol type at the satellite. The algorithm is applied to data from a time series of CZCS orbits during which both the Saharan dust and a bluish haze due to chlorophyll presence have been observed in the coastal zone. The results are compared with in situ measurements and to values derived from CZCS imagery by single-component methods, showing reasonable agreement between in situ measurements and values estimated by the two-component method. In imagery derived using single-component methods, the aerosol and chlorophyll fields appeared confounded in imagery where several types of aerosol were present.

  10. Effect of forest canopy closure on incoming solar radiance

    SciTech Connect

    Dottavio, C.L.

    1981-04-01

    In order to better understand the physical processes involved in defoliation assessment from remotely sensed data, a field study was designed to investigate the effect of forest canopy closure and other environmental variables on incoming solar radiation. Diffuse radiation measurements were recorded in red, infrared, and middle infrared wavelengths using the Mark 2 three band field radiometer. Results to date indicate that the percent canopy closure is the single most important variable affecting incoming solar radiation. In the visible and near infrared regions, interaction between time of day and date (defined later as solar zenith angle) also affect radiometric response. Aspect has only limited influence on radiance response. These same variables do not influence middle infrared response, however. Uniformity of the forest canopy appears to be more important. These results are compared to LANDSAT MSS classification results of gypsy moth defoliation.

  11. Effect of forest canopy closure on incoming solar radiance

    NASA Technical Reports Server (NTRS)

    Dottavio, C. L. (Principal Investigator)

    1981-01-01

    In order to better understand the physical processes involved in defoliation assessment from remotely sensed data, a field study was designed to investigate the effect of forest canopy closure and other environmental variables on incoming solar radiation. Diffuse radiation measurements were recorded in red, infrared, and middle infrared wavelengths using the Mark 2 three band field radiometer. Results to date indicate that the percent canopy closure is the single most important variable affecting incoming solar radiation. In the visible and near infrared regions, interaction between time of day and date (defined later as solar zenith angle) also affect radiometric response. Aspect has only limited influence on radiance response. These same variables do not influence middle infrared response, however. Uniformity of the forest canopy appears to be more important. These results are compared to LANDSAT MSS classification results of gypsy moth defoliation.

  12. A robust pseudo-inverse spectral filter applied to the Earth Radiation Budget Experiment (ERBE) scanning channels

    NASA Technical Reports Server (NTRS)

    Avis, L. M.; Green, R. N.; Suttles, J. T.; Gupta, S. K.

    1984-01-01

    Computer simulations of a least squares estimator operating on the ERBE scanning channels are discussed. The estimator is designed to minimize the errors produced by nonideal spectral response to spectrally varying and uncertain radiant input. The three ERBE scanning channels cover a shortwave band a longwave band and a ""total'' band from which the pseudo inverse spectral filter estimates the radiance components in the shortwave band and a longwave band. The radiance estimator draws on instantaneous field of view (IFOV) scene type information supplied by another algorithm of the ERBE software, and on a priori probabilistic models of the responses of the scanning channels to the IFOV scene types for given Sun scene spacecraft geometry. It is found that the pseudoinverse spectral filter is stable, tolerant of errors in scene identification and in channel response modeling, and, in the absence of such errors, yields minimum variance and essentially unbiased radiance estimates.

  13. Gravity Wave Variances and Propagation Derived from AIRS Radiances

    NASA Technical Reports Server (NTRS)

    Gong, Jie; Wu, Dong L.; Eckermann, S. D.

    2012-01-01

    As the first gravity wave (GW) climatology study using nadir-viewing infrared sounders, 50 Atmospheric Infrared Sounder (AIRS) radiance channels are selected to estimate GW variances at pressure levels between 2-100 hPa. The GW variance for each scan in the cross-track direction is derived from radiance perturbations in the scan, independently of adjacent scans along the orbit. Since the scanning swaths are perpendicular to the satellite orbits, which are inclined meridionally at most latitudes, the zonal component of GW propagation can be inferred by differencing the variances derived between the westmost and the eastmost viewing angles. Consistent with previous GW studies using various satellite instruments, monthly mean AIRS variance shows large enhancements over meridionally oriented mountain ranges as well as some islands at winter hemisphere high latitudes. Enhanced wave activities are also found above tropical deep convective regions. GWs prefer to propagate westward above mountain ranges, and eastward above deep convection. AIRS 90 field-of-views (FOVs), ranging from +48 deg. to -48 deg. off nadir, can detect large-amplitude GWs with a phase velocity propagating preferentially at steep angles (e.g., those from orographic and convective sources). The annual cycle dominates the GW variances and the preferred propagation directions for all latitudes. Indication of a weak two-year variation in the tropics is found, which is presumably related to the Quasi-biennial oscillation (QBO). AIRS geometry makes its out-tracks capable of detecting GWs with vertical wavelengths substantially shorter than the thickness of instrument weighting functions. The novel discovery of AIRS capability of observing shallow inertia GWs will expand the potential of satellite GW remote sensing and provide further constraints on the GW drag parameterization schemes in the general circulation models (GCMs).

  14. Absolute Radiometric Calibration of EUNIS-06

    NASA Technical Reports Server (NTRS)

    Thomas, R. J.; Rabin, D. M.; Kent, B. J.; Paustian, W.

    2007-01-01

    The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a soundingrocket payload that obtains imaged high-resolution spectra of individual solar features, providing information about the Sun's corona and upper transition region. Shortly after its successful initial flight last year, a complete end-to-end calibration was carried out to determine the instrument's absolute radiometric response over its Longwave bandpass of 300 - 370A. The measurements were done at the Rutherford-Appleton Laboratory (RAL) in England, using the same vacuum facility and EUV radiation source used in the pre-flight calibrations of both SOHO/CDS and Hinode/EIS, as well as in three post-flight calibrations of our SERTS sounding rocket payload, the precursor to EUNIS. The unique radiation source provided by the Physikalisch-Technische Bundesanstalt (PTB) had been calibrated to an absolute accuracy of 7% (l-sigma) at 12 wavelengths covering our bandpass directly against the Berlin electron storage ring BESSY, which is itself a primary radiometric source standard. Scans of the EUNIS aperture were made to determine the instrument's absolute spectral sensitivity to +- 25%, considering all sources of error, and demonstrate that EUNIS-06 was the most sensitive solar E W spectrometer yet flown. The results will be matched against prior calibrations which relied on combining measurements of individual optical components, and on comparisons with theoretically predicted 'insensitive' line ratios. Coordinated observations were made during the EUNIS-06 flight by SOHO/CDS and EIT that will allow re-calibrations of those instruments as well. In addition, future EUNIS flights will provide similar calibration updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI.

  15. Remotely sensed and laboratory spectral signatures of an ocean-dumped acid waste

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Collins, V. G.

    1977-01-01

    An ocean-dumped acid waste plume was studied by using a rapid scanning spectrometer to remotely measure ocean radiance from a helicopter. The results of these studies are presented and compared with results from sea truth samples and laboratory experiments. An ocean spectral reflectance signature and a laboratory spectral transmission signature were established for the iron-acid waste pollutant. The spectrally and chemically significant component of the acid waste pollutant was determined to be ferric iron.

  16. Retrieval of temperature and water vapor from combined satellite and ground based ultra-spectral measurements

    NASA Astrophysics Data System (ADS)

    Jian, Yongxiao

    Ultra-spectrometers with a spectral resolution better than 1 cm-1, such as AIRS on the AQUA, IASI on the Metop-A/B, and CrIS on the Suomi-NPP, have become operational during the past decade. The radiance spectra measured by these satellite-borne spectrometers provide soundings of the atmosphere with relatively high vertical resolution and high accuracy except for the lower atmosphere. Meanwhile, many ground-based ultra-spectrometers based on the Michelson Interferometer have been incorporated into the Department of Energy Atmospheric Radiation Measurement facilities and aboard NOAA research vessels. These instruments provide temperature and water vapor soundings within the planetary boundary layer continuously with very high vertical resolution. This dissertation develops a retrieval procedure which can combine the radiance measured by ground-based spectrometers and coincident observation from satellite-borne instruments to improve retrieval results throughout the lower atmosphere. To verify the feasibility and improved accuracy of the combined retrieval, 90 clear sky cases from four in-situ radiosonde measurement locations or geographical regions, were selected for this study. Each region consists of radiosonde measurements of temperature and water vapor, downwelling radiance spectra measured at approximately the balloon launch time, and upwelling radiance observation by IASI at the location and time coincident with the surface radiance and radiosonde measurements. These cases indicate, that when compared with the retrieval from upwelling radiance or downwelling radiance spectra only, there is a significant improvement of the retrieval using combined upwelling and downwelling radiance spectra is observed. At altitude below the 800 hPa pressure level, the errors using the combined retrieval are about 0.5 -- 1 K in temperature, and 20 -- 40 % for water vapor mixing ratio. These errors are approximately one-third the magnitude of errors for the sounding retrieval

  17. A Sphere-Scanning Radiometer for Rapid Directional Measurements of Sky and Ground Radiance: the PARABOLA Field Instrument

    NASA Technical Reports Server (NTRS)

    Deering, D. W.; Leone, P.

    1984-01-01

    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.

  18. Optically based technique for producing merged spectra of water-leaving radiances from ocean color remote sensing.

    PubMed

    Mélin, Frédéric; Zibordi, Giuseppe

    2007-06-20

    An optically based technique is presented that produces merged spectra of normalized water-leaving radiances L(WN) by combining spectral data provided by independent satellite ocean color missions. The assessment of the merging technique is based on a four-year field data series collected by an autonomous above-water radiometer located on the Acqua Alta Oceanographic Tower in the Adriatic Sea. The uncertainties associated with the merged L(WN) obtained from the Sea-viewing Wide Field-of-view Sensor and the Moderate Resolution Imaging Spectroradiometer are consistent with the validation statistics of the individual sensor products. The merging including the third mission Medium Resolution Imaging Spectrometer is also addressed for a reduced ensemble of matchups.

  19. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  20. Comparative study of spectral diffuse-only and diffuse-specular radiative transfer models and field-collected data in the LWIR

    NASA Astrophysics Data System (ADS)

    Stoyanov, Dimitar M.; Marciniak, Michael A.; Meola, Joseph

    2015-09-01

    The sensitivity of hyper-spectral remote sensing to the directional reflectance of surfaces was studied using both laboratory and field measurements. Namely, the effects of the specular- and diffuse-reflectance properties of a set of eight samples, ranging from high to low in both total reflectance and specularity, on diffuse-only and diffusespecular radiative transfer models in the long-wave infrared (LWIR, 7-14-μm wavelength) were studied. The samples were measured in the field as a set of eight panels, each in two orientations, with surface normal pointing toward zenith and tipped at 45° from zenith. The field-collected data also included down-welling spectral sky radiance at several angles from zenith to the horizon, ground spectral radiance, panel spectral radiances in both orientations, Infragold® spectral radiances in both orientations near each panel location, and panel temperatures. Laboratory measurements included spectral hemispherical, specular and diffuse directional reflectance (HDR, SDR and DDR) for each sample for several reflectance angles with respect to the surface normal. The diffuse-only radiative transfer model used the HDR data, while the diffuse-specular model used the SDR and DDR data. Both calculated spectral reflected and self-emitted radiances for each panel, using the field-collected sky radiance data to avoid uncertainties associated with atmospheric models. The modeled spectral radiances were then compared to the field-collected values to quantify differences in moving from an HDR-based model to an SDR/DDR model in the LWIR for a variety of surface-reflectance types.

  1. Constrained adaptive bias correction for satellite radiances assimilation in the ECMWF 4D-Var

    NASA Astrophysics Data System (ADS)

    Han, Wei; Bormann, Niels

    2016-04-01

    Satellite radiance observations are typically affected by biases that arise from uncertainties in the absolute calibration, the radiative transfer modeling, or other aspects. These biases have to be removed for the successful assimilation of the data in NWP systems. Two key problems have been identified in bias correction: Firstly, bias corrections can drift towards unrealistic values in regions where there is strong model error and relatively few "anchor" observations, ie, observations that have little systematic error and therefore allow the separation between model and observation bias. Examples where this has been particularly problematic are channels sensitive to ozone or stratospheric temperature. Secondly, there is undesired interaction between the quality control and bias correction for observations where bias-corrected observation departures are used for quality control and where these departures show skewed distributions (e.g., in case of cloud detection). In the study, we investigated potential solutions to these problems by providing further constraints using potential available information, such as constraints on the size of the bias correction and innovative bias correction metrics using uncertainty estimation from calibration and radiative transfer. This has been studied in the full ECMWF global 4D-Var system, using data from microwave sounders which are sensitive to stratospheric temperature. The resulting enhanced bias corrections was assessed in the context of other assimilated observations (in particular radiosondes and GPS radio occultation measurements), and through comparisons of MLS temperature retrieval data in stratosphere and mesosphere. The constrained adaptive bias correction of AMSU-A stratospheric sounding channels reduces the biases in stratosphere and improves the medium range forecasts in both stratosphere and troposphere.

  2. Reflectance-based calibration of SeaWiFS. II. Conversion to radiance.

    PubMed

    Barnes, Robert A; Zalewski, Edward F

    2003-03-20

    For instruments that carry onboard solar diffusers to orbit, such as the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), it is possible to convert the instrument's reflectance measurements to radiance measurements by knowledge of the solar irradiance. This process, which generally requires the application of a solar irradiance model, is described. The application of the irradiance model is separate from the measurements by the instrument and from the instrument's reflectance calibration. In addition, SeaWiFS was calibrated twice before launch for radiance response by use of radiance sources with calibrations traceable to the National Institute of Standards and Technology. With the inclusion of the at-launch diffuser-based radiance calibration, SeaWiFS has three possible radiance calibrations forthe start of on-orbit operations. The combination of these three into a single calibration requires changes of 4% or less for the current at-launch radiance calibration of the instrument. Finally, this process requires changes of 4% or less for the reflectance calibration coefficients to provide consistency among the radiance calibration, the reflectance calibration, and the solar irradiance.

  3. SeaWiFS technical report series. Volume 23: SeaWiFS prelaunch radiometric calibration and spectral characterization

    NASA Technical Reports Server (NTRS)

    Barnes, Robert A.; Holmes, Alan W.; Barnes, William L.; Esaias, Wayne E.; Mcclain, Charles R.; Svitek, Tomas; Hooker, Stanford B.; Firestone, Elaine R.; Acker, James G.

    1994-01-01

    Based on the operating characteristics of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), calibration equations have been developed that allow conversion of the counts from the radiometer into Earth-existing radiances. These radiances are the geophysical properties the instrument has been designed to measure. SeaWiFS uses bilinear gains to allow high sensitivity measurements of ocean-leaving radiances and low sensitivity measurements of radiances from clouds, which are much brighter than the ocean. The calculation of these bilinear gains is central to the calibration equations. Several other factors within these equations are also included. Among these are the spectral responses of the eight SeaWiFS bands. A band's spectral response includes the ability of the band to isolate a portion of the electromagnetic spectrum and the amount of light that lies outside of that region. The latter is termed out-of-band response. In the calibration procedure, some of the counts from the instrument are produced by radiance in the out-of-band region. The number of those counts for each band is a function of the spectral shape of the source. For the SeaWiFS calibration equations, the out-of-band responses are converted from those for the laboratory source into those for a source with the spectral shape of solar flux. The solar flux, unlike the laboratory calibration, approximates the spectral shape of the Earth-existing radiance from the oceans. This conversion modifies the results from the laboratory radiometric calibration by 1-4 percent, depending on the band. These and other factors in the SeaWiFS calibration equations are presented here, both for users of the SeaWiFS data set and for researchers making ground-based radiance measurements in support of Sea WiFS.

  4. The Use of Correlated k-Distributions to Account for the Radiative Effect of Molecular Absorption Upon Satellite Measured Radiances

    NASA Technical Reports Server (NTRS)

    Kratz, David P.

    1998-01-01

    Establishing the radiative effect of molecular absorption (emission) in the atmosphere is critical to the proper interpretation of satellite retrieved radiances. Without an accurate accounting for molecular absorption, the assignment of radiative transfer processes to observed radiative effects could be fraught errors. Moreover, since the spectral characteristics of molecular absorption can change quickly with wavenumber, the adaptation of climate model parameterizations has the potential to lead to dubious results unless the chosen spectral range corresponds closely to the response function of the satellite instrument. Thus, an initiative has been undertaken to construct parameterizations that will account for the molecular absorption found in the spectral ranges of several satellite radiometers. Because of its efficiency and accuracy in calculating the molecular absorption for nonhomogeneous paths, the correlated k-distribution procedure has proven to be the most effective parameterization (Fu and Liou, 1992, and Kratz, 1995). A further advantage of the correlated k- distribution procedure is its ability to be incorporated directly into multiple scattering routines that consider scattering, as well as absorption, by clouds and aerosol particles.

  5. Influence the temperatures of the surface and gaseous environment of Mercury on IR radiance spectra -the results of numerical simulation

    NASA Astrophysics Data System (ADS)

    Blecka, Maria I.

    Mercury's atmosphere is very thin and is mainly made out of sodium but also tracers like potassium, oxygen and tiny amount of helium have been detected. There are various sources which provide supply of gases to the surface of the planet. The major sources are: the Solar Wind, which delivers hydrogen and helium, meteoritic impacts, which vaporize the surface rocks, and as the incoming objects, provides a small amounts of oxygen, iron, silicon and other components to the gaseous mixture, and also "volcanic" events as a sources of sulfurous gases can appear. The surface of Mercury shows quite extreme differences in temperature from one place to another, as well as temporal variations. The differences that occur are due to changes in distance from the Sun, day/night differences and changes, related to the latitude. The model we present provides estimates of the spectral radiance of Mercury in the Mid-Infrared spectral range. In our simulation the cumulative effects of the surface and detected species of the thin atmosphere of Mercury have been taken into account. The spectral shape of emissivity, taken from existing databases or published papers, characteristic for already known mineralogical composition were used. The various temperatures of the surface and parameters of the atmosphere have been taken into account. Our calculations are directly connected with the future spectrometric measurements of "MERTIS" on Bepi Colombo mission to Mercury. We expect that the future interpretation of data will benefit from our simulation of the signal to be acquired.

  6. Absolute intensity of radiation emitted by uranium plasmas

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.; Lee, J. H.; Mcfarland, D. R.

    1975-01-01

    The absolute intensity of radiation emitted by fissioning and nonfissioning uranium plasmas in the spectral range from 350 nm to 1000 nm was measured. The plasma was produced in a plasma-focus apparatus and the plasma properties are simular to those anticipated for plasma-core nuclear reactors. The results are expected to contribute to the establishment of design criteria for the development of plasma-core reactors.

  7. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  8. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  9. Results in coastal waters with high resolution in situ spectral radiometry: The Marine Optical System ROV

    NASA Astrophysics Data System (ADS)

    Yarbrough, Mark; Feinholz, Michael; Flora, Stephanie; Houlihan, Terrance; Johnson, B. Carol; Kim, Yong S.; Murphy, Marilyn Y.; Ondrusek, Michael; Clark, Dennis

    2007-09-01

    The water-leaving spectral radiance is a basic ocean color remote sensing parameters required for the vicarious calibration. Determination of water-leaving spectral radiance using in-water radiometry requires measurements of the upwelling spectral radiance at several depths. The Marine Optical System (MOS) Remotely Operated Vehicle (ROV) is a portable, fiber-coupled, high-resolution spectroradiometer system with spectral coverage from 340 nm to 960 nm. MOS was developed at the same time as the Marine Optical Buoy (MOBY) spectrometer system and is optically identical except that it is configured as a profiling instrument. Concerns with instrument self-shadowing because of the large exterior dimensions of the MOS underwater housing led to adapting MOS and ROV technology. This system provides for measurement of the near-surface upwelled spectral radiance while minimizing the effects of shadowing. A major advantage of this configuration is that the ROV provides the capability to acquire measurements 5 cm to 10 cm below the water surface and is capable of very accurate depth control (1 cm) allowing for high vertical resolution observations within the very near-surface. We describe the integrated system and its characterization and calibration. Initial measurements and results from observations of coral reefs in Kaneohe Bay, Oahu, extremely turbid waters in the Chesapeake Bay, Maryland, and in Case 1 waters off Southern Oahu, Hawaii are presented.

  10. Basic optics, aerosol optics, and the role of scattering for sky radiance

    NASA Astrophysics Data System (ADS)

    Horvath, Helmuth

    2014-05-01

    The radiance of the night sky is determined by the available light and the scattering properties of the atmosphere (particles and gases). The scattering phase function of the aerosol has a strong dependence on the scattering angle, and depending on the viewing direction different parts of the atmosphere and the ground reflectivity give the most important contribution. The atmospheric radiance cannot be altered by optical instruments. On the other hand the light flux of a distant star increases with the size of the telescope, thus fainter stars become visible. Light extinction, scattering function, atmospheric radiance, ground reflectivity, color effects and others are discussed in detail and a simple theoretical treatment is given.

  11. Dependence of NOAA-AVHRR recorded radiance on scan angle, atmospheric turbidity and unresolved cloud

    NASA Technical Reports Server (NTRS)

    Piwinski, D. J.; Schoch, L. B.; Duggin, M. J.; Whitehead, V.; Ryland, E.

    1984-01-01

    Experimental evidence on the scan angle and sun angle dependence of radiance recorded by the Advanced Very High Resolution Radiometer (AVHRR) devices on the NOAA-6 and NOAA-7 satellites is presented. The effects of atmospheric turbidity at various scan angles is shown, and simulations of angular anisotropy and recorded radiance are compared with the recorded digital data from the AVHRR obtained over the Great Plains area of the US. Evidence is presented on the effects of unresolved cloud on the recorded radiance and vegetative indices from uniform, vegetative targets.

  12. Electroacoustical imaging technique for encoding incoherent radiance fields as Gabor elementary signals

    NASA Technical Reports Server (NTRS)

    Fales, C. L.; Huck, F. O.

    1985-01-01

    A technique is presented for directly encoding incoherent radiance fields as Gabor elementary signals. This technique uses an electro-acoustic sensor to modulate the electronic charges induced by the incident radiance field with the electric fields generated by Gaussian modulated sinusoidal acoustic waves. The resultant signal carries the amplitude and phase information required for localizing spatial frequencies of the radiance field. These localized spatial frequency representations provide a link between the either geometric or Fourier transform representations currently used in computer vision and pattern recognition.

  13. Relationship of crop radiance to alfalfa agronomic values

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Red and photographic infrared spectral data of alfalfa were collected at the time of the third and fourth cuttings using a hand-held radiometer for the earlier alfalfa cutting. 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 alfalfa of the later cutting, which had experienced a period of severe drought stress which limited growth, the spectral variables were found to be highly correlated with the estimated drought scores.

  14. Bandwidth and spectral stray light effects in the NASA GSFC Radiometric Calibration Facility primary transfer radiometer

    NASA Astrophysics Data System (ADS)

    Barnes, Robert A.; Cooper, John W.; Marketon, John E.; Brown, Steven W.; Johnson, B. Carol; Butler, James J.

    2006-08-01

    As part of an effort to reduce uncertainties in the radiometric calibrations of integrating sphere sources and standard lamp irradiance sources, the Goddard Space Flight Center (GSFC) Radiometric Calibration Facility's (RCF) primary radiometer was characterized at the NIST facility for Spectral Irradiance and Radiance Calibrations with Uniform Sources (SIRCUS). Based on those measurements, a nominal slit scattering function was developed for the radiometer. This allowed calculations of band averaged spectral radiances and irradiances for the radiometer's measurements of sphere and standard lamp sources, respectively. From these calculations the effects of bandwidth and spectral stray light were isolated for measurements in the blue spectral region. These effects, which depend on the spectral distribution of the source being measured, can be as large as 8% for measurements at 400 nm. The characterization results and a correction algorithm for these effects are presented here.

  15. Determination and error analysis of emittance and spectral emittance measurements by remote sensing

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Kumar, R.

    1977-01-01

    The author has identified the following significant results. From the theory of remote sensing of surface temperatures, an equation of the upper bound of absolute error of emittance was determined. It showed that the absolute error decreased with an increase in contact temperature, whereas, it increased with an increase in environmental integrated radiant flux density. Change in emittance had little effect on the absolute error. A plot of the difference between temperature and band radiance temperature vs. emittance was provided for the wavelength intervals: 4.5 to 5.5 microns, 8 to 13.5 microns, and 10.2 to 12.5 microns.

  16. Scientific applications of the Marine-Atmospheric Emitted Radiance Interferometer

    NASA Astrophysics Data System (ADS)

    Minnett, P. J.; Hanafin, J.; Szczodrak, M.; Key, E. L.; Izaguirre, M.; Brown, O. B.

    2006-12-01

    The Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) is a well-calibrated, ship-based Fourier Transform Infrared spectroradiometer. Its development by the University of Wisconsin SSEC in the mid- 90's was founded on a land-based analog, the AERI, which has been in continuous operation at several ARM (Atmospheric Radiation Measurement) sites around the world. The primary objective of the M-AERI was to provide accurate skin sea-surface temperatures (SST) for the validation of satellite retrievals, specifically those from MODIS (MODerate-resolution Imaging Spectroradiometer on the NASA satellites Terra and Aqua). Over the past decade, the measured spectra from the oceanic and atmospheric emission have found a wide range of applications beyond SST retrievals. Just a few topics that have been addressed using M-AERI spectra include the study of the physical behavior of the oceanic skin layer, the oceanic infrared emissivity, and the near-surface air temperature and air-sea temperature differences, and in deriving profiles of temperature and humidity in the lower marine troposphere. Here we present an overview of such applications and results.

  17. Spectral emissivity of cirrus clouds

    NASA Technical Reports Server (NTRS)

    Beck, Gordon H.; Davis, John M.; Cox, Stephen K.

    1993-01-01

    The inference of cirrus cloud properties has many important applications including global climate studies, radiation budget determination, remote sensing techniques and oceanic studies from satellites. Data taken at the Parsons Kansas site during the FIRE II project are used for this study. On November 26 there were initially clear sky conditions gradually giving way to a progressively thickening cirrus shield over a period of a few hours. Interferometer radiosonde and lidar data were taken throughout this event. Two techniques are used to infer the downward spectral emittance of the observed cirrus layer. One uses only measurements and the other involves measurements and FASCODE III calculations. FASCODE III is a line-by line radiance/transmittance model developed at the Air Force Geophysics Laboratory.

  18. Spectral and Spread Spectral Teleportation

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  19. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  20. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate.

  1. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate. PMID:11262641

  2. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  3. Classification images predict absolute efficiency.

    PubMed

    Murray, Richard F; Bennett, Patrick J; Sekuler, Allison B

    2005-02-24

    How well do classification images characterize human observers' strategies in perceptual tasks? We show mathematically that from the classification image of a noisy linear observer, it is possible to recover the observer's absolute efficiency. If we could similarly predict human observers' performance from their classification images, this would suggest that the linear model that underlies use of the classification image method is adequate over the small range of stimuli typically encountered in a classification image experiment, and that a classification image captures most important aspects of human observers' performance over this range. In a contrast discrimination task and in a shape discrimination task, we found that observers' absolute efficiencies were generally well predicted by their classification images, although consistently slightly (approximately 13%) higher than predicted. We consider whether a number of plausible nonlinearities can account for the slight under prediction, and of these we find that only a form of phase uncertainty can account for the discrepancy.

  4. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

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

    SciTech Connect

    Not Available

    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.

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

    NASA Technical Reports Server (NTRS)

    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.)

  7. Assessment of the first radiances received from the VSSR Atmospheric Sounder (VAS) instrument

    NASA Technical Reports Server (NTRS)

    Chesters, D.; Uccellini, L. W.; Montgomery, H.; Mostek, A.; Robinson, W.

    1981-01-01

    The first orderly, calibrated radiances from the VAS-D instrument on the GOES-4 satellite are examined for: image quality, radiometric precision, radiation transfer verification at clear air radiosonde sites, regression retrieval accuracy, and mesoscale analysis features. Postlaunch problems involving calibration and data processing irregularities of scientific or operational significance are included. The radiances provide good visual and relative radiometric data for empirically conditioned retrievals of mesoscale temperature and moisture fields in clear air.

  8. A Fast Radiative Transfer Parameterization Under Cloudy Condition in Solar Spectral Region

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Liu, X.; Yang, P.; Wang, C.

    2014-12-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) system, which is proposed and developed by NASA, will directly measure the Earth's thermal infrared spectrum (IR), the spectrum of solar radiation reflected by the Earth and its atmosphere (RS), and radio occultation (RO). IR, RS, and RO measurements provide information on the most critical but least understood climate forcings, responses, and feedbacks associated with the vertical distribution of atmospheric temperature and water vapor, broadband reflected and emitted radiative fluxes, cloud properties, surface albedo, and surface skin temperature. To perform Observing System Simulation Experiments (OSSE) for long term climate observations, accurate and fast radiative transfer models are needed. The principal component-based radiative transfer model (PCRTM) is one of the efforts devoted to the development of fast radiative transfer models for simulating radiances and reflecatance observed by various hyperspectral instruments. Retrieval algorithm based on PCRTM forward model has been developed for AIRS, NAST, IASI, and CrIS. It is very fast and very accurate relative to the training radiative transfer model. In this work, we are extending PCRTM to UV-VIS-near IR spectral region. To implement faster cloudy radiative transfer calculations, we carefully investigated the radiative transfer process under cloud condition. The cloud bidirectional reflectance was parameterized based on off-line 36-stream multiple scattering calculations while few other lookup tables were generated to describe the effective transmittance and reflectance of the cloud-clear-sky coupling system in solar spectral region. The bidirectional reflectance or the irradiance measured by satellite may be calculated using a simple fast radiative transfer model providing the type of cloud (ice or water), optical depth of the cloud, optical depth of both atmospheric trace gases above and below clouds, particle size of the cloud, as well

  9. CONTINUATION OF DATA ANALYSIS SOFTWARE DEVELOPMENT FOR THE ATMOSPHERIC EMITTED RADIANCE INTER- FEROMETER (AERI)

    SciTech Connect

    Robert Knuteson; Wayne Feltz; Shepard Clough

    2005-09-30

    Data from the Atmospheric Emitted Radiance Interferometer (AERI) has been analyzed under the ARM Fourier Transform Data Analysis Tools science team project. A portion of the effort was accomplished through a subcontract to S. A. Clough of Atmospheric Environmental Research (AER), Inc. This section of the proposal highlights a few important accomplishments obtained during the past grant period. Specific accomplishments include: 1) The AERIplus temperature and moisture retrieval algorithm (Feltz et al. 2003, 2005) has now implemented a new fast model based upon LBLRTM. The fast model provides a doubling of vertical resolution within the first 100 hPa of atmosphere (surface to 900 hPa) from 10 hPa spacing to 5 hPa. This algorithm has been implemented at Pacific Northwest National Laboratories to upgrade previous AERI retrieval software. A peer reviewed paper has been published with regard to this work along with Value Added Product (VAP) technical document available through ARM web site. 2) Developed an objective methodology to detect planetary boundary layer (PBL) height using the AERI derived potential temperature field. AERI temperature and moisture data are also used to correlate the perturbation temperature and moisture in time within the planetary boundary layer (PBL) to view the structure of PBL turbulence and convection. 3) The temporal resolution of the DOE ARM AERI systems is now being increased to less than 20 seconds (currently ~ 8 minutes depending on system). The University of Wisconsin mobile AERI system was deployed three times (Texas 2002 at SGP, CRYSTAL-FACE in southern Florida, and AWEX 2003 at SGP) collecting data at 40 second temporal resolution. The DOE ARM science team has requested that all DOE ARM AERI systems be upgraded to run in rapid sampling mode (including the ARM Mobile Facility AERI) to provide improved sampling of changing cloud characteristics using high spectral resolution infrared data. This grant has facilitated in the

  10. Validity Assessment of Pixel Linear Spectral Mixing Through Laboratory Measurements

    NASA Astrophysics Data System (ADS)

    Mobasheri, M. R.; Dehnavi, S.; Maghsoudi, Y.

    2015-12-01

    In order to understand the characteristics of the data collected by hyperspectral imaging systems, it is important to discuss the physics behind the scene radiance field incident on the imaging system. A dominant effect in hyperspectral remote sensing is the mixing of radiant energies contributed from different materials present in a given pixel. The basic assumption of mixture modelling is that within a given scene, the surface is covered by a small number of distinct materials that have relatively constant spectral properties. It is most common to assume that the radiance reflected by different materials in a pixel can spectrally combine in a linear additive manner to produce the pixel radiance/reflectance, even when that might not be the case e.g. where the mixing process leads to nonlinear combinations of the radiance and where the linear assumption fails to hold. This can occur where there is significant relative three-dimensional structure within a given pixel. Without detailed knowledge of the dimensional structure, it can be very difficult to correctly ``un-mix'' the contributions of the various materials. This work aims to evaluate the correctness of the linear assumption in the mixture modelling using some laboratory measurements. Study was conducted using some sheets made of cellulose materials of different colours in 400-800 nm spectral range. Experimental results have shown that a correction term must be applied to the gains and offsets in the linear model. The obtained results can be extended to satellite sensors that acquire images in the above mentioned spectral range.

  11. Influence of Humidity on the Aerosol Scattering Coefficient and Its Effect on the Upwelling Radiance During ACE-2

    NASA Technical Reports Server (NTRS)

    Gasso, B. S.; Hegg, D. A.; Covert, D. S.; Collins, D.; Noone, K.; Oestroem, E.; Schmid, B.; Russell, P. B.; Livingston, J. M.; Durkee, P. A.; Jonsson, H.

    2000-01-01

    Aerosol scattering coefficients (sigma(sub sp)) have been measured over the ocean at different relative humidities (RH) as a function of attitude in the region surrounding the Canary Islands during the Second Aerosol Characterization Experiment (ACE-2) in June and July 1997. The data were collected by the University of Washington passive humidigraph (UWPH) mounted on the Pelican research aircraft. Concurrently, particle size distributions absorption coefficients and aerosol optical depth were measured throughout 17 flights. A parameterization of sigma(sub sp) as a function of RH was utilized to assess the impact of aerosol hydration on the upwelling radiance (normalized to the solar constant and cosine of zenith angle). The top of the atmosphere radiance signal was simulated at wavelengths corresponding to visible and near-infrared bands or the EOS-AM ("Terra") detectors, MODIS and MISR. The UWPH measured (sigma(sub sp)) at 2 RHs, one below and the other above ambient conditions. Ambient (sigma(sub sp)) was obtained by interpolation of these 2 measurements. The data were stratified in terms of 3 types of aerosols: Saharan dust, clean marine (marine boundary layer background) and polluted marine aerosols (i.e., 2- or 1-day old polluted aerosols advected from Europe). An empirical relation for the dependence of (sigma(sub sp)) on RH, defined by (sigma(sub sp))(RH) = k. ((1 - RH/100)(exp -gamma), was used with the hygroscopic exponent gamma derived from the data. The following gamma values were obtained for the 3 aerosol types: gamma(dust) = 0.23 +/- 0.05, gamma(clean marine) = 0.69 +/- 0.06 and gamma(polluted marine) = 0.57 + 0.06. Based on the measured (gamma)(s), the above equation was utilized to derive aerosol models with different hygroscopicities. The satellite simulation signal code 6S was used to compute the upwelling radiance corresponding to each of those aerosol models at several ambient humidities. For the pre-launch estimated precision of the sensors and

  12. Influence of Humidity On the Aerosol Scattering Coefficient and Its Effect on the Upwelling Radiance During ACE-2

    NASA Technical Reports Server (NTRS)

    Gasso, S.; Hegg, D. A.; Covert, D. S.; Collins, D.; Noone, K. J.; Oestroem, E.; Schmid, B.; Russell, P. B.; Livingston, J. M.; Durkee, P. A.

    2000-01-01

    Aerosol scattering coefficients (sigma(sub sp)) have been measured over the ocean at different relative humidities (RH) as a function of altitude in the region surrounding the Canary Islands during the Second Aerosol Characterization Experiment (ACE-2) in June and July 1997. The data were collected by the University of Washington passive humidigraph (UWPH) mounted on the Pelican research aircraft. Concurrently, particle size distributions, absorption coefficients and aerosol optical depth were measured throughout 17 flights. A parameterization of sigma(sub sp) as a function of RH was utilized to assess the impact of aerosol hydration on the upwelling radiance (normalized to the solar constant and cosine of zenith angle). The top of the atmosphere radiance signal was simulated at wavelengths corresponding to visible and near-infrared bands of the EOS (Earth Observing System) AM-1 (Terra) detectors, MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multi-angle Imaging Spectroradiometer). The UWPH measured sigma(sub sp) at two RHs, one below and the other above ambient conditions. Ambient sigma(sub sp) was obtained by interpolation of these two measurements. The data were stratified in terms of three types of aerosols: Saharan dust, clean marine (marine boundary layer background) and polluted marine aerosols (i.e., two- or one-day old polluted aerosols advected from Europe). An empirical relation for the dependence of sigma(sub sp) on RH, defined by sigma(sub sp)(RH) = k.(1 - RH/100)(sup gamma), was used with the hygroscopic exponent gamma derived from the data. The following gamma values were obtained for the 3 aerosol types: gamma(dust) = 0.23 +/- 0.05, gamma(clean marine) = 0.69 +/- 0.06 and gamma(polluted marine) = 0.57 +/- 0.06. Based on the measured gammas, the above equation was utilized to derive aerosol models with different hygroscopicities. The satellite simulation signal code 6S was used to compute the upwelling radiance corresponding to each

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  15. Joint retrieval of aerosol and water-leaving radiance from multispectral, multiangular and polarimetric measurements over ocean

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Dubovik, Oleg; Zhai, Peng-Wang; Diner, David J.; Kalashnikova, Olga V.; Seidel, Felix C.; Litvinov, Pavel; Bovchaliuk, Andrii; Garay, Michael J.; van Harten, Gerard; Davis, Anthony B.

    2016-07-01

    An optimization approach has been developed for simultaneous retrieval of aerosol properties and normalized water-leaving radiance (nLw) from multispectral, multiangular, and polarimetric observations over ocean. The main features of the method are (1) use of a simplified bio-optical model to estimate nLw, followed by an empirical refinement within a specified range to improve its accuracy; (2) improved algorithm convergence and stability by applying constraints on the spatial smoothness of aerosol loading and Chlorophyll a (Chl a) concentration across neighboring image patches and spectral constraints on aerosol optical properties and nLw across relevant bands; and (3) enhanced Jacobian calculation by modeling and storing the radiative transfer (RT) in aerosol/Rayleigh mixed layer, pure Rayleigh-scattering layers, and ocean medium separately, then coupling them to calculate the field at the sensor. This approach avoids unnecessary and time-consuming recalculations of RT in unperturbed layers in Jacobian evaluations. The Markov chain method is used to model RT in the aerosol/Rayleigh mixed layer and the doubling method is used for the uniform layers of the atmosphere-ocean system. Our optimization approach has been tested using radiance and polarization measurements acquired by the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) over the AERONET USC_SeaPRISM ocean site (6 February 2013) and near the AERONET La Jolla site (14 January 2013), which, respectively, reported relatively high and low aerosol loadings. Validation of the results is achieved through comparisons to AERONET aerosol and ocean color products. For comparison, the USC_SeaPRISM retrieval is also performed by use of the Generalized Retrieval of Aerosol and Surface Properties algorithm (Dubovik et al., 2011). Uncertainties of aerosol and nLw retrievals due to random and systematic instrument errors are analyzed by truth-in/truth-out tests with three Chl a concentrations, five aerosol loadings

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

    NASA Technical Reports Server (NTRS)

    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

  17. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  18. Familial Aggregation of Absolute Pitch

    PubMed Central

    Baharloo, Siamak; Service, Susan K.; Risch, Neil; Gitschier, Jane; Freimer, Nelson B.

    2000-01-01

    Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as “AP-1.” As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed. PMID:10924408

  19. Spectral super-resolution reflectance retrieval from remotely sensed imaging spectrometer data.

    PubMed

    Jia, Guorui; Hueni, Andreas; Tao, Dongxing; Geng, Ruonan; Schaepman, Michael E; Zhao, Huijie

    2016-08-22

    Existing atmospheric correction methods retrieve surface reflectance keeping the same nominal spectral response functions (SRFs) as that of the airborne/spaceborne imaging spectrometer radiance data. Since the SRFs vary dependent on sensor type and configuration, the retrieved reflectance of the same ground object varies from sensor to sensor as well. This imposes evident limitations on data validation efforts between sensors at surface reflectance level. We propose a method to retrieve super-resolution reflectance at the surface, by combining the first-principles atmospheric correction method FLAASH (fast line-of-sight atmospheric analysis of spectral hypercubes) with spectral super-resolution of imaging spectrometer radiance data. This approach is validated by comparing airborne AVIRIS (airborne visible/infrared imaging spectrometer) and spaceborne Hyperion data. The results demonstrate that the super-resolution reflectance in spectral bands with sufficiently high signal-to-noise ratio (SNR) serves as intermediate quantity to cross validate data originating from different imaging spectrometers.

  20. Role of laser beam radiance in different ceramic processing: A two wavelengths comparison

    NASA Astrophysics Data System (ADS)

    Shukla, Pratik; Lawrence, Jonathan

    2013-12-01

    Effects of laser beam radiance (brightness) of the fibre and the Nd3+:YAG laser were investigated during surface engineering of the ZrO2 and Si3N4 advanced ceramics with respect to dimensional size and microstructure of both of the advanced ceramics. Using identical process parameters, the effects of radiance of both the Nd3+:YAG laser and a fibre laser were compared thereon the two selected advanced ceramics. Both the lasers showed differences in each of the ceramics employed in relation to the microstructure and grain size as well as the dimensional size of the laser engineered tracks-notwithstanding the use of identical process parameters namely spot size; laser power; traverse speed; Gaussian beam modes; gas flow rate and gas composition as well the wavelengths. From this it was evident that the difference in the laser beam radiance between the two lasers would have had much to do with this effect. The high radiance fibre laser produced larger power per unit area in steradian when compared to the lower radiance of the Nd3+:YAG laser. This characteristically produced larger surface tracks through higher interaction temperature at the laser-ceramic interface. This in turn generated bigger melt-zones and different cooling rates which then led to the change in the microstructure of both the Si3N4 and ZrO2 advance ceramics. Owing to this, it was indicative that lasers with high radiance would result in much cheaper and cost effective laser assisted surface engineering processes, since lower laser power, faster traverse speeds, larger spot sizes could be used in comparison to lasers with lower radiance which require much slower traverse speed, higher power levels and finer spot sizes to induce the same effect thereon materials such as the advanced ceramics.

  1. The spectral emissivity of prairie and pasture grasses at Konza Prairie, Kansas

    NASA Technical Reports Server (NTRS)

    Palluconi, Frank; Kahle, Anne B.; Hoover, Gordon; Conel, James E.

    1990-01-01

    Field measurements of spectral radiances are used to determine precise values of the spectral emissivity of grass-thatch-soil complexes to facilitate remote temperature determinations. The emissivity variation with wavelength is very small, emissivity is close to unity, and emissivity is fairly constant in terms of emission angle, land practice, and season. The prairie surface is therefore similar to a grey body and a quasiideal emitter, although determinations of the kinetic temperature are required to confirm the results.

  2. On the Relative Stability of CERES Reflected Shortwave and MISR and MODIS Visible Radiance Measurements During the Terra Satellite Mission

    NASA Technical Reports Server (NTRS)

    Corbett, J. G.; Loeb, N. G.

    2015-01-01

    Fifteen years of visible, near-infrared, and broadband shortwave radiance measurements from Clouds and the Earth's Radiant Energy System (CERES), Multiangle Imaging Spectroradiometer (MISR), and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board NASA's Terra satellite are analyzed in order to assess their long-term relative stability for climate purposes. A regression-based approach between CERES, MODIS, and MISR (An camera only) reflectances is used to calculate the bias between the different reflectances relative to a reference year. When compared to the CERES shortwave broadband reflectance, relative drift between the MISR narrowbands is within 1%/decade. Compared to the CERES shortwave reflectance, the MODIS narrowband reflectances show a relative drift of less than -1.33%/decade. When compared to MISR, the MODIS reflectances show a relative drift of between -0.36%/decade and -2.66%/decade. We show that the CERES Terra SW measurements are stable over the time period relative to CERES Aqua. Using this as evidence that CERES Terra may be absolutely stable, we suggest that the CERES, MISR, and MODIS instruments meet the radiometric stability goals for climate applications set out in Ohring et al. (2005).

  3. Assimilation of hyperspectral infrared sounder radiances under cloudy skies in a regional NWP model

    NASA Astrophysics Data System (ADS)

    Wang, Pei

    Satellite measurements are an important source of global observations in support of numerical weather prediction (NWP). The assimilation of satellite radiances under clear skies has greatly improved NWP forecast scores. Since most of the data assimilation models are used for the clear radiances assimilation, an important step for satellite radiances assimilation is the clear location detection. Good clear detection could effectively remove the cloud contamination and keep the clear observations for assimilation. In this dissertation, a new detection method uses collocated high spatial resolution imager data onboard the same platform as the satellite sounders to help IR sounders subpixel cloud detection, such as the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS), the Crosstrack Infrared Sounder (CrIS) and Visible Infrared Imaging Radiometer Suite (VIIRS). The MODIS cloud mask provides a level of confidence for the observed skies to help AIRS Field-of-View (FOVs) cloud detection. By reducing the cloud contamination, a cold bias in the temperature field and a wet bias in the moisture field are corrected for the atmospheric analysis fields. These less cloud affected analysis fields further improve hurricane track and intensity forecast. The availability of satellite observations that can be assimilated in the model is limited if only the clear radiances are assimilation. An effective way to use the thermodynamic information under partially cloudy regions is to assimilate the "cloud-cleared" radiances (CCRs); CCRs are also called clear equivalent radiances. Because the CCRs are the equivalent clear radiances from the partially cloudy FOVs, they can be directly assimilated into the current data assimilation models without modifications. The AIRS CCRs are assimilated and compared with the AIRS using stand-alone cloud detection and collocated cloud detection. The assimilation of AIRS cloud-cleared radiances directly affects

  4. Effect of Aerosol Variation on Radiance in the Earth's Atmosphere-Ocean System.

    PubMed

    Plass, G N; Kattawar, G W

    1972-07-01

    The reflected and transmitted radiance is calculated for a realistic model of the atmosphere-ocean system. Multiple scattering to all orders as well as anisotropic scattering from aerosols are taken into account by a Monte Carlo technique. The probability for reflection or refraction at the ocean surface is calculated for each photon. Scattering and absorption by water molecules (Rayleigh) and by hydrosols (Mie) are taken into account within the ocean. The radiance is calculated for a normal aerosol distribution as well as for a three and ten times normal distribution. Calculations are also made for an aerosol layer near the earth as well as for one in the stratosphere. The upward radiance at the top of the atmosphere depends strongly on the total number of aerosols but not on their spatial distribution. Variations in the ozone amount also have little effect on the upward radiance. The calculations are made at the following wavelengths: 0.7 micro, 0.9 micro, 1.67 micro. The radiance above and below the ocean surface as well as the flux at various levels are also discussed.

  5. Radiance and photon noise: imaging in geometrical optics, physical optics, quantum optics and radiology

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    The statistics of detector outputs produced by an imaging system are derived from basic radiometric concepts and definitions. We show that a fundamental way of describing a photon-limited imaging system is in terms of a Poisson random process in spatial, angular, and wavelength variables. We begin the paper by recalling the concept of radiance in geometrical optics, radiology, physical optics, and quantum optics. The propagation and conservation laws for radiance in each of these domains are reviewed. Building upon these concepts, 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 (capable of measuring radiance on a photon-by-photon basis). This allows us to rigorously show how the concept of radiance is related to the statistical properties of detector outputs and to the information content of a single detected photon. A Monte-Carlo technique, which is derived from the Boltzmann transport equation, is presented as a way to estimate probability density functions to be used in reconstruction from photon-processing data.

  6. Advanced infrared sounder subpixel cloud detection with imagers and its impact on radiance assimilation in NWP

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Li, Jun; Li, Jinlong; Li, Zhenglong; Schmit, Timothy J.; Bai, Wenguang

    2014-03-01

    Accurate cloud detection is very important for infrared (IR) radiance assimilation; improved cloud detection could reduce cloud contamination and hence improve the assimilation. Although operational numerical weather prediction (NWP) centers are using IR sounder radiance data for cloud detection, collocated high spatial resolution imager data could help sounder subpixel cloud detection and characterization. IR sounder radiances with improved cloud detection using Atmospheric Infrared Sounder (AIRS)/Moderate Resolution Imaging Spectroradiometer (MODIS) were assimilated for Hurricane Sandy (2012). Forecast experiments were run with Weather Research and Forecasting (WRF) as the forecast model and the Three-Dimensional Variational Assimilation (3DVAR)-based Gridpoint Statistical Interpolation (GSI) as the analysis system. Results indicate that forecasts of both hurricane track and intensity are substantially improved when the collocated high spatial resolution MODIS cloud mask is used for AIRS subpixel cloud detection for assimilating radiances. This methodology can be applied to process Crosstrack Infrared Sounder (CRIS)/Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPOESS Preparatory Project (NPP)/Joint Polar Satellite System (JPSS) and Infrared Atmospheric Sounding Interferometer (IASI)/Advanced Very High Resolution Radiometer (AVHRR) onboard the Metop series for improved radiance assimilation in NWP.

  7. Field observations of the relation between satellite and sea radiances in coastal waters

    NASA Astrophysics Data System (ADS)

    Aas, Eyvind; Sørensen, Kai

    1995-08-01

    Estimates of the different contributions to the satellite radiance above the outer Oslofjord are presented. The contribution from the sea is of the order of 10% of the total signal, and the part due to reflection from the sea surface constitutes 10-20%. The presence of land may increase the satellite radiance up to 4-9%, but such effects, which are probably reduced to 1/e at a distance of 1 km from the coast, cannot be detected in the present measurements. In situ observations of the marine radiance are corrected for shadings by ship and instrument and for varying solar altitude. The average correction for the self-shading effect of the marine instrument becomes 30-50% in these waters. The linear relations between satellite and sea radiances are determined with correlation coefficients of better than 0.95. The observed minimum value of the satellite radiance (or darkest pixel) is not a satisfactory approximation for the atmospheric correction. It is concluded that, in coastal waters and at the present stage, satellite observations have to be combined with field measurements to obtain reliable results.

  8. Evaluation of the Impact of AIRS Radiance and Profile Data Assimilation in Partly Cloudy Regions

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi; Jedlovec, Gary

    2013-01-01

    Improvements to global and regional numerical weather prediction have been demonstrated through assimilation of data from NASA s Atmospheric Infrared Sounder (AIRS). Current operational data assimilation systems use AIRS radiances, but impact on regional forecasts has been much smaller than for global forecasts. Retrieved profiles from AIRS contain much of the information that is contained in the radiances and may be able to reveal reasons for this reduced impact. Assimilating AIRS retrieved profiles in an identical analysis configuration to the radiances, tracking the quantity and quality of the assimilated data in each technique, and examining analysis increments and forecast impact from each data type can yield clues as to the reasons for the reduced impact. By doing this with regional scale models individual synoptic features (and the impact of AIRS on these features) can be more easily tracked. This project examines the assimilation of hyperspectral sounder data used in operational numerical weather prediction by comparing operational techniques used for AIRS radiances and research techniques used for AIRS retrieved profiles. Parallel versions of a configuration of the Weather Research and Forecasting (WRF) model with Gridpoint Statistical Interpolation (GSI) are run to examine the impact AIRS radiances and retrieved profiles. Statistical evaluation of a long-term series of forecast runs will be compared along with preliminary results of in-depth investigations for select case comparing the analysis increments in partly cloudy regions and short-term forecast impacts.

  9. Use of MODIS Cloud Top Pressure to Improve Assimilation Yields of AIRS Radiances in GSI

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi

    2014-01-01

    Radiances from hyperspectral sounders such as the Atmospheric Infrared Sounder (AIRS) are routinely assimilated both globally and regionally in operational numerical weather prediction (NWP) systems using the Gridpoint Statistical Interpolation (GSI) data assimilation system. However, only thinned, cloud-free radiances from a 281-channel subset are used, so the overall percentage of these observations that are assimilated is somewhere on the order of 5%. Cloud checks are performed within GSI to determine which channels peak above cloud top; inaccuracies may lead to less assimilated radiances or introduction of biases from cloud-contaminated radiances.Relatively large footprint from AIRS may not optimally represent small-scale cloud features that might be better resolved by higher-resolution imagers like the Moderate Resolution Imaging Spectroradiometer (MODIS). Objective of this project is to "swap" the MODIS-derived cloud top pressure (CTP) for that designated by the AIRS-only quality control within GSI to test the hypothesis that better representation of cloud features will result in higher assimilated radiance yields and improved forecasts.

  10. Adjusting the tasseled cap brightness and greenness factors for atmospheric path radiance and absorption on a pixel by pixel basis

    NASA Technical Reports Server (NTRS)

    Jackson, R. D.; Slater, P. N.; Pinter, P. J. (Principal Investigator)

    1982-01-01

    A radiative transfer model was used to convert ground measured reflectances into the radiance at the top of the atmosphere, for several levels of atmospheric path radiance. The radiance in MSS7 (0.8 to 1.1 m) was multiplied by the transmission fraction for atmospheres having different levels of precipitable water. The radiance values were converted to simulated LANDSAT digital counts for four path radiance levels and four levels of precipitable water. These values were used to calculate the Kauth-Thomas brightness, greenness, yellowness, and nonsuch factors. Brightness was affected by surface conditions and path radiance. Greenness was affected by surface conditions, path radiance, and precipitable water. Yellowness was affected by path radiance and nonsuch by precipitable water, and both factors changed only slightly with surface conditions. Yellowness and nonsuch were used to adjust brightness and greenness to produce factors that were affected only by surface conditions such as soils and vegetation, and not by path radiance and precipitable water.

  11. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  12. Apparatus for absolute pressure measurement

    NASA Technical Reports Server (NTRS)

    Hecht, R. (Inventor)

    1969-01-01

    An absolute pressure sensor (e.g., the diaphragm of a capacitance manometer) was subjected to a superimposed potential to effectively reduce the mechanical stiffness of the sensor. This substantially increases the sensitivity of the sensor and is particularly useful in vacuum gauges. An oscillating component of the superimposed potential induced vibrations of the sensor. The phase of these vibrations with respect to that of the oscillating component was monitored, and served to initiate an automatic adjustment of the static component of the superimposed potential, so as to bring the sensor into resonance at the frequency of the oscillating component. This establishes a selected sensitivity for the sensor, since a definite relationship exists between resonant frequency and sensitivity.

  13. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  14. Comparison of Reflected Solar Radiance Using Aqua Modis and Airborne Remote Sensing (case : Deep Convective Clouds and Cirrus Clouds)

    NASA Astrophysics Data System (ADS)

    Krisna, T. C.; Ehrlich, A.; Werner, F.; Wendisch, M.

    2015-12-01

    Deep Convective Clouds (DCCs) have key role in the tropical region. Despite they only have small spatial coverage, but they account most of the total precipitation in these region which often make flooding. There are such of aviation accidents caused by strong vertical wind, hailing, icing and lightning inside the clouds. Pollutions caused by biomass burning and land degradation can change the aerosol properties as well as cloud properties, therefore will influence the radiation and formation of the DCCs. Those are the major reasons that better understanding of DCCs formation and life cycle are necessary. Between Sept. 01 - Oct. 14, ACRIDICON (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Concevtive Clouds Systems) campaign was conducted over Amazonia. It is suitable area to be the site-study due to has strong contrast environtment (pristine and polluted), regular convection activities and stable meteorological condition. In this study we focus on the 2 satellite validation missions designed to fly collocated but in different altitude with A-TRAIN constellation. In order to study DCCs-solar radiation interaction, we use SMART (Spectral Modular Airborne Radiation Measurements System) installed on HALO (High Altitude and Long-Range Research Aircraft) which measures spectral Irradiance (F) and Radiance (I) at the wavelength between 300-2200 nm corresponding to satellite. Due to the limitation in spatial and temporal, airborne measurements only give snapshots of atmosphere condition and DCCs formation, therefore we use multi-satellite data as DCCs have high vertical and horizontal distance, long temporal development and complex form. The comparison of AQUA MODIS and SMART Radiance at 645 nm (non-absorbing) in the clear-sky condition gives strong agreement, but in the multilayer-cloud condition gives worse and results in high underestimation (-86%) in SMART data especially at lower altitude. The bias is caused by interference from clouds

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

    NASA Astrophysics Data System (ADS)

    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

  16. Hyper-spectral Atmospheric Sounding. Appendixes 1

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Zhou, D. K.; Revercomb, H. E.; Huang, H. L.; Antonelli, P.; Mango, S. A.

    2002-01-01

    The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) is the first hyper-spectral remote sounding system to be orbited aboard a geosynchronous satellite. The GETS is designed to obtain revolutionary observations of the four dimensional atmospheric temperature, moisture, and wind structure as well as the distribution of the atmospheric trace gases, CO and O3. Although GIFTS will not be orbited until 2006-2008, a glimpse at the its measurement capabilities has been obtained by analyzing data from the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Test-bed-Interferometer (NAST-I) and Aqua satellite Atmospheric Infrared Sounder (AIRS). In this paper we review the GIFTS experiment and empirically assess measurement expectations based on meteorological profiles retrieved from the NAST aircraft and Aqua satellite AIRS spectral radiances.

  17. Atmospheric effect on spectral signature - measurements

    NASA Astrophysics Data System (ADS)

    Kaufman, Yoram J.

    In order to improve the quality of remote sensing there is a need to estimate the atmospheric effect on the remotely sensed image, from the image itself. This can be done by recognition of some surface features with known radiative characteristics. For this purpose measurements of the atmospheric effect on the spectral signature of surface cover were conducted during hazy conditions. Simultaneous measurements of the aerosol optical thickness and its vertical distribution were carried. The results of the measurements are used here to study the spectral dependence of the atmospheric effect on remote sensing of vegetated fields (forest, corn field etc.) and water bodies, and to verify theoretical predictions. It is suggested that the radiances over dark areas (e.g. water in the near IR and forest in the visible) can be used to derive the aerosol optical thickness. Combined with climatological information, the derived optical thickness can be used to perform corrections of the atmospheric effect (not given here).

  18. In-Flight Absolute Radiometric Calibration of the Landsat Thematic Mapper

    NASA Astrophysics Data System (ADS)

    Kastner, Carol Jane

    The in-flight absolute radiometric calibration of the Thematic Mapper (TM) is being conducted using the results of field measurements at White Sands, New Mexico. These measurements are made to characterize the ground and atmosphere at the time the TM is acquiring an image of White Sands. The data are used as input to a radiative transfer code that computes the radiance at the entrance pupil of the TM. The calibration is obtained by comparing the digital counts associated with the TM image of the measured ground site with the radiative transfer code result. The calibrations discussed here are for the first four visible and near -infrared bands of the TM. In this dissertation the data reduction for the first calibration attempts on January 3, 1983, and July 8, 1984, is discussed. Included are a review of radiative transfer theory and a discussion of model atmospheric parameters as defined for the White Sands area. These model parameters are used to assess the errors associated with the calibration procedure. Each input parameter to the radiative transfer code is varied from its model value in proportion to the uncertainty with which it can be determined. The effects of these uncertainties on the predicted radiances are determined. It is thought that the optical depth components (tau)(,Ray), (tau)(,Mie), (tau)(,oz), and (tau)(,H(,2)O) can be measured to within 10%, 2%, 10%, and 30%, respectively. For the white gypsum sand, surface reflectance uniformity is on the order of 1.5%, and the overall uncertainty in measured reflectance is about 2%. This is due to an uncertainty in the reflectance factor of the calibration plates. The greatest uncertainty in calibration is attributed to our uncertainty in the aerosol parameters, in particular the imaginary component of refractive index. The cumulative effect of these uncertainties is thought to produce an uncertainty in computed radiance of about 5%.

  19. Remote application for spectral collection

    NASA Astrophysics Data System (ADS)

    Cone, Shelli R.; Steele, R. J.; Tzeng, Nigel H.; Firpi, Alexer H.; Rodriguez, Benjamin M.

    2016-05-01

    In the area of collecting field spectral data using a spectrometer, it is common to have the instrument over the material of interest. In certain instances it is beneficial to have the ability to remotely control the spectrometer. While several systems have the ability to use a form of connectivity to capture the measurement it is essential to have the ability to control the settings. Additionally, capturing reference information (metadata) about the setup, system configuration, collection, location, atmospheric conditions, and sample information is necessary for future analysis leading towards material discrimination and identification. This has the potential to lead to cumbersome field collection and a lack of necessary information for post processing and analysis. The method presented in this paper describes a capability to merge all parts of spectral collection from logging reference information to initial analysis as well as importing information into a web-hosted spectral database. This allows the simplification of collecting, processing, analyzing and storing field spectra for future analysis and comparisons. This concept is developed for field collection of thermal data using the Designs and Prototypes (D&P) Hand Portable FT-IR Spectrometer (Model 102). The remote control of the spectrometer is done with a customized Android application allowing the ability to capture reference information, process the collected data from radiance to emissivity using a temperature emissivity separation algorithm and store the data into a custom web-based service. The presented system of systems allows field collected spectra to be used for various applications by spectral analysts in the future.

  20. New spectral methods in cloud and aerosol remote sensing applications

    NASA Astrophysics Data System (ADS)

    Schmidt, K. Sebastian; McBride, Patrick; Pilewskie, Peter; Feingold, Graham; Jiang, Hongli

    2010-05-01

    We present new remote sensing techniques that rely on spectral observations of clouds and aerosols in the solar wavelength range. As a first example, we show how the effects of heterogeneous clouds, aerosols of changing optical properties, and the surface within one pixel can be distinguished by means of their spectral signatures. This example is based on data from the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS, Houston, Texas, 2006), Large Eddy Simulations (LES) of polluted boundary layer clouds, and 3-dimensional radiative transfer calculations. In a second example, we show that the uncertainty of cloud retrievals can be improved considerably by exploiting the spectral information around liquid water absorption features in the near-infrared wavelength range. This is illustrated with spectral transmittance data from the NOAA International Chemistry Experiment in the Arctic LOwer Troposphere (ICEALOT, 2008). In contrast to reflected radiance, transmitted radiance is only weakly sensitive to cloud effective drop radius, and only cloud optical thickness can be obtained from the standard dual-channel technique. We show that effective radius and liquid water path can also be retrieved with the new spectral approach, and validate our results with microwave liquid water path measurements.

  1. A Study of Global Cirrus Cloud Morphology with AIRS Cloud-clear Radiances (CCRs)

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Gong, Jie

    2012-01-01

    Version 6 (V6) AIRS cloud-clear radiances (CCR) are used to derive cloud-induced radiance (Tcir=Tb-CCR) at the infrared frequencies of weighting functions peaked in the middle troposphere. The significantly improved V 6 CCR product allows a more accurate estimation of the expected clear-sky radiance as if clouds are absent. In the case where strong cloud scattering is present, the CCR becomes unreliable, which is reflected by its estimated uncertainty, and interpolation is employed to replace this CCR value. We find that Tcir derived from this CCR method are much better than other methods and detect more clouds in the upper and lower troposphere as well as in the polar regions where cloud detection is particularly challenging. The cloud morphology derived from the V6 test month, as well as some artifacts, will be shown.

  2. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-07-03

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  3. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2008-10-21

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  4. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-07-17

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  5. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-10-02

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  6. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2009-09-01

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. An approximation to multiple scattering in the earth's atmosphere Almucantar radiance formulation

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Deepak, A.

    1981-01-01

    An empirical expression is derived to account for the molecular multiple scattering contribution to the almucantar radiance field. Formulas for the correction factors which incorporate the effects of multiple scattering and nonzero ground albedo are also given. The use and accuracy of the multiple-scattering approximation in direct problems of radiative transfer associated with almucantar radiance are discussed and illustrated by examples. It is shown that in almost all instances, inclusion of the molecular multiple-scattering contribution reduces the errors obtained with the single-scattering approximation by a factor of at least 2.

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

    SciTech Connect

    Feltz, W. F.; Howell, H. B.; Comstock, J.; Mahon, R.; Turner, D. D.; Smith, W. L.; Woolf, H. M.; Halter, T.

    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.

  10. Upwelling radiance at 976 nm measured from space using the OPALS CCD camera on the ISS

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Kovalik, Joseph M.; Oaida, Bogdan V.; Abrahamson, Matthew; Wright, Malcolm W.

    2015-03-01

    The Optical Payload for Lasercomm Science (OPALS) Flight System on-board the International Space Station uses a charge coupled device (CCD) camera to detect a beacon laser from Earth. Relative measurements of the background contributed by upwelling radiance under diverse illumination conditions and varying surface terrain is presented. In some cases clouds in the field-of-view allowed a comparison of terrestrial and cloud-top upwelling radiance. In this paper we will report these measurements and examine the extent of agreement with atmospheric model predictions.

  11. Modeling hyperspectral observations of vegetation fluorescence from photosystem level to top-of-atmosphere radiance spectra

    NASA Astrophysics Data System (ADS)

    Verhoef, W.

    2011-12-01

    In support of the candidate ESA mission FLEX, models have been developed to simulate vegetation chlorophyll fluorescence and its observation on the level of single leaves, the canopy and from space. The Fluspect model is based on the PROSPECT leaf model and includes an additional module which calculates the excitation-fluorescence matrix for both sides of the leaf by means of an efficient doubling algorithm. Fluorescence spectra for white incident light, and of course the spectra of reflectance and transmittance, are computed as well. The FluorSAIL model is a numerical variant of SAIL which calculates top-of-canopy fluorescent radiance in the direction of viewing for given incident radiation spectra from the sun and the sky, obtained from the MODTRAN radiative transfer code. In a recent version called FluorSAIL3, high spectral resolution data (0.1 nm) from MODTRAN5 (beta) are used by the model to simulate observations by the candidate FLEX mission. The model computes the directional canopy reflectance with and without fluorescence for the given incident radiation spectra obtained from MODTRAN and the results have been used to evaluate several algorithms for the retrieval of fluorescence from the apparent reflectance signal. In this contribution emphasis will be on the detection of the fluorescence signal, the dependence of fluorescence observations on leaf chlorophyll content and other PROSPECT parameters, canopy structure, and observational conditions, including the properties of the atmosphere. In addition, some attention is paid to the definition of fluorescence quantum efficiencies at photosystem level, leaf level, and canopy level. This is important for the study of the relation between canopy fluorescence and actual photosynthesis. From the simulations it can be concluded that the interpretation of the fluorescence signal is complex, and probably the comparison of actual observations of spectra of fluorescence and reflectance with spectra simulated by a

  12. [Research on ground scenery spectral radiation source with tunable spectra].

    PubMed

    Xiang, Jin-rong; Ren, Jian-wei; Li, Bao-yong; Wan, Zhi; Liu, Ze-xun; Liu, Hong-xing; Li, Xian-sheng; Sun, Jing-xu

    2015-02-01

    A spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a ground scenery spectral database was established in the control system. An improved genetic algorithm was proposed, and a large number of ground scenery spectra were produced by the simulator. Spectral similarity and the average spectral matching error of several typical ground scenery spectra were further analyzed. Spectral similarity of red bands, green bands, blue bands and near-infrared spectral band also was discussed. When the radiance of the target was 50 W x (m2 x sr)(-1), the average spectral matching error was less than 10% and spectral similarity was greater than 0.9, up to 0.983. Spectral similarity of red band, green band, blue band and near-infrared band (especially green band and near-infrared band) was less than that of full-band. Compared with blue band and red band, spectral similarity of green band and near-infrared band low-amplitude maximum can rearch 50%. Ground scenery spectrum radiation source can be used as radiometric calibration source for optical remote sensor, and calibration error, which is caused by objectives and calibration sources spectral mismatch, can be effectively reduced. PMID:25970881

  13. Feasibility of interstitial near-infrared radiance spectroscopy platform for ex vivo canine prostate studies: optical properties extraction, hemoglobin and water concentration, and gold nanoparticles detection.

    PubMed

    Grabtchak, Serge; Montgomery, Logan G; Whelan, William M

    2014-05-01

    The canine prostate is a close match for the human prostate and is used in research of prostate cancers. Determining accurately optical absorption and scattering properties of the gland in a wide spectral range (preferably in a minimally invasive way), linking optical properties to concentrations of major endogenous chromophores, and detecting the presence of localized optical inhomogeneities like inclusions of gold nanoparticles for therapeutic and diagnostic purposes, are among the major challenges for researchers. The goal of the article is to demonstrate a feasibility of the multifunctional radiance spectroscopy platform in providing the required information. For ex vivo canine prostate, extraction of the effective attenuation and diffusion coefficients using relative cw radiance measurements was demonstrated in the 650- to 900-nm range. The derived absorption coefficient was decomposed to contributions from 9.0 μM HbO₂, 29.6 μM Hb, and 0.47 fractional volume of H₂O. Detection of a localized inclusion containing ∼1.5·1010 gold nanorods (0.8 μg Au) at 10 mm distance from the urethra was achieved with the detector in the urethra and the light source in a virtual rectum position. The platform offers the framework for a systematic study of various chromophores in the prostate that can be used as comprehensive diagnostic markers.

  14. Absolute configuration of isovouacapenol C

    PubMed Central

    Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

    2010-01-01

    The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003 Å). An intra­molecular C—H⋯O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H⋯O hydrogen bonds. C⋯O [3.306 (2)–3.347 (2) Å] short contacts and C—H⋯π inter­actions also occur. PMID:21588364

  15. Pre-Launch Absolute Calibration of CCD/CBERS-2B Sensor

    PubMed Central

    Ponzoni, Flávio Jorge; Albuquerque, Bráulio Fonseca Carneiro

    2008-01-01

    Pre-launch absolute calibration coefficients for the CCD/CBERS-2B sensor have been calculated from radiometric measurements performed in a satellite integration and test hall in the Chinese Academy of Space Technology (CAST) headquarters, located in Beijing, China. An illuminated integrating sphere was positioned in the test hall facilities to allow the CCD/CBERS-2B imagery of the entire sphere aperture. Calibration images were recorded and a relative calibration procedure adopted exclusively in Brazil was applied to equalize the detectors responses. Averages of digital numbers (DN) from these images were determined and correlated to their respective radiance levels in order to calculate the absolute calibration coefficients. It has been the first time these pre-launch absolute calibration coefficients have been calculated considering the Brazilian image processing criteria. Now it will be possible to compare them to those that will be calculated from vicarious calibration campaigns. This comparison will permit the CCD/CBERS-2B monitoring and the frequently data updating to the user community.

  16. Tropospheric Ozone Near-Nadir-Viewing IR Spectral Sensitivity and Ozone Measurements from NAST-I

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Smith, William L.; Larar, Allen M.

    2001-01-01

    Infrared ozone spectra from near nadir observations have provided atmospheric ozone information from the sensor to the Earth's surface. Simulations of the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I) from the NASA ER-2 aircraft (approximately 20 km altitude) with a spectral resolution of 0.25/cm were used for sensitivity analysis. The spectral sensitivity of ozone retrievals to uncertainties in atmospheric temperature and water vapor is assessed in order to understand the relationship between the IR emissions and the atmospheric state. In addition, ozone spectral radiance sensitivity to its ozone layer densities and radiance weighting functions reveals the limit of the ozone profile retrieval accuracy from NAST-I measurements. Statistical retrievals of ozone with temperature and moisture retrievals from NAST-I spectra have been investigated and the preliminary results from NAST-I field campaigns are presented.

  17. Frequency-domain analysis of absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Svitlov, S.

    2012-12-01

    An absolute gravimeter is analysed as a linear time-invariant system in the frequency domain. Frequency responses of absolute gravimeters are derived analytically based on the propagation of the complex exponential signal through their linear measurement functions. Depending on the model of motion and the number of time-distance coordinates, an absolute gravimeter is considered as a second-order (three-level scheme) or third-order (multiple-level scheme) low-pass filter. It is shown that the behaviour of an atom absolute gravimeter in the frequency domain corresponds to that of the three-level corner-cube absolute gravimeter. Theoretical results are applied for evaluation of random and systematic measurement errors and optimization of an experiment. The developed theory agrees with known results of an absolute gravimeter analysis in the time and frequency domains and can be used for measurement uncertainty analyses, building of vibration-isolation systems and synthesis of digital filtering algorithms.

  18. Aerosol Properties From Combined Oxygen A Band Radiances and Lidar

    NASA Technical Reports Server (NTRS)

    Winker, Dave; Zhai, Peng-Wang; Hu, Yongxiang

    2015-01-01

    We have developed a new aerosol retrieval technique based on combing high-resolution A band spectra with lidar profiles. Our goal is the development of a technique to retrieve aerosol absorption, one of the critical parameters affecting the global radiation budget and one which is currently poorly constrained by satellite measurements. Our approach relies on two key factors: 1) the use of high spectral resolution (17,000:1) measurements which resolve the A-band line structure, and 2) the use of co-located lidar profile measurements to constrain the vertical distribution of scatterers in the forward model. The algorithm has been developed to be applied to observations from the CALIPSO and OCO-2 satellites, flying in formation as part of the A-train constellation. We describe the approach and present simulated retrievals to illustrate performance potential.

  19. Retrieval of cloud top height, effective emissivity, and particle size, from aircraft high-spectral-resolution infrared measurements

    NASA Astrophysics Data System (ADS)

    Antonelli, Paolo B.; Ackerman, Steven A.; Menzel, W. Paul; Huang, Hung-Lung; Baum, Bryan A.; Smith, William L.

    2002-02-01

    In this study we compare different approaches to retrieve Cloud Top Height (CTH), Cloud Effective Emissivity (CEE), and the Cloud Particle Size (CPS) from aircraft high-spectral resolution infrared measurements. Two independent methods are used to infer CTH. One approach is based on a high spectral resolution version of the CO2 Slicing algorithm characterized by a statistically based selection of the optimal channel pairs. Another approach the Minimum Local Emissivity Variance algorithm (MLEV) takes advantage of high-resolution observations in the 8-12 micron region to simultaneously derive CTH and CEE. Once CTH has been retrieved a third method, based on the comparison between simulated and observed radiances, is used to infer CPS and CEE. Simulated radiances are computed for 18 microwindows between 8.5 and 12 microns. The cirrus scattering calculations are based on three-dimensional randomly oriented ice columns assuming six different particle size distributions. Multiple scattering calculations are performed for 26 different cloud optical thicknesses (COT) between 0 and 20. The simulated radiances are then compared to the observed radiances to infer COT and CPS for each spectral measurement. We applied these approaches to High-resolution Interferometer Sounder (HIS), National Polar-Orbiting Operational Environmental Satellite System Airborne Sounder Testbed-Interferometer (NAST-I) and Scanning-HIS (S-HIS) data. The preliminary results, consistent between the different algorithms, suggest that the high spectral resolution measurements improve the accuracy of the cloud property retrievals.

  20. Absolute vicarious calibration of Landsat-8 OLI and Resourcesat-2 AWiFS sensors over Rann of Kutch site in Gujarat

    NASA Astrophysics Data System (ADS)

    Sharma, Shweta; Sridhar, V. N.; Prajapati, R. P.; Rao, K. M.; Mathur, A. K.

    2016-05-01

    In this work, vicarious calibration coefficients for all the four bands (green, red, NIR and SWIR) of Resourcesat-2 AWiFS sensor for four dates during Dec 2013-Nov 2014 and for seven bands (blue, green, red, NIR, SWIR1, SWIR2 and PAN) of OLI sensor onboard Landsat-8 for six dates during Dec 2013-Feb 2015 were estimated using field measured reflectance and measured atmospheric parameters during sensor image acquisition over Rann of Kutch site in Gujarat. The top of atmosphere (TOA) at-satellite radiances for all the bands were simulated using 6S radiative transfer code with field measured reflectance, synchronous atmospheric measurements and respective sensor's spectral response functions as an input. These predicted spectral radiances were compared with the radiances from the respective sensor's image in the respective band over the calibration site. Cross-calibration between the sensors AWiFS and OLI was also attempted using near-simultaneous same day image acquisition. Effect of spectral band adjustment factor was also studied with OLI sensor taken as reference sensor. Results show that the variation in average estimated radiance ratio for the AWiFS sensor was found to be within 10% for all the bands, whereas, for OLI sensor, the variation was found to be within 6% for all the bands except green and SWIR2 for which the variation was 8% and 11% respectively higher than the 5% uncertainty of the OLI sensor specification for TOA spectral radiance. At the 1σ level, red, NIR, SWIR1 and Panchromatic bands of OLI sensor showed close agreement between sensor-measured and vicarious TOA radiance resulting no change in calibration coefficient and hence indicating no sensor degradation. Two sets of near-simultaneous SBAFs were derived from respective ground measured target reflectance profiles and applied to the AWiFS and it was observed that overall, SBAF compensation provides a significant improvement in sensor agreement. The reduction in the difference between AWiFS and

  1. Path-radiance correction by polarization observation of Sun glint glitter for remote measurements of tropospheric greenhouse gases.

    PubMed

    Aoki, Tadao; Aoki, Teruo; Fukabori, Masashi

    2002-08-20

    High-accuracy remote measurement of greenhouse gases is hampered by contamination of the field of view by the path radiance of solar radiation scattered from clouds and aerosols. A method is proposed for eliminating the effect of path radiance by differentiating two components of polarized light. The polarization of path radiance is measured directly at the wave-number region of strong water-vapor absorption. Using this measurement, we eliminate the components of path radiance involved in other bands, which are used for greenhouse gas measurements, by differentiating two components of the polarized light. It is shown that the effect of path radiance on retrieving the column amount of gases potentially can be reduced to below 0.1%. PMID:12206201

  2. Path-radiance correction by polarization observation of Sun glint glitter for remote measurements of tropospheric greenhouse gases.

    PubMed

    Aoki, Tadao; Aoki, Teruo; Fukabori, Masashi

    2002-08-20

    High-accuracy remote measurement of greenhouse gases is hampered by contamination of the field of view by the path radiance of solar radiation scattered from clouds and aerosols. A method is proposed for eliminating the effect of path radiance by differentiating two components of polarized light. The polarization of path radiance is measured directly at the wave-number region of strong water-vapor absorption. Using this measurement, we eliminate the components of path radiance involved in other bands, which are used for greenhouse gas measurements, by differentiating two components of the polarized light. It is shown that the effect of path radiance on retrieving the column amount of gases potentially can be reduced to below 0.1%.

  3. Radiance and polarization in the diffusion region with an arbitrary scattering phase matrix

    NASA Astrophysics Data System (ADS)

    Sun, Bingqiang; Kattawar, George W.; Yang, Ping

    2016-11-01

    Radiance and polarization patterns in an optically deep region, the so-called diffusion region or asymptotic region, of a homogeneous atmosphere or ocean, depend mainly on the scattering phase matrix and the single-scattering albedo of the medium. The radiance and polarization properties in the diffusion region for an arbitrary scattering phase matrix can be obtained in terms of a series of the generalized spherical functions. The number of terms is closely related to the single-scattering albedo of the medium. If the medium is conservative, the radiance is isotropic in conjunction with no polarization. If the single-scattering albedo is close to 1, several terms are sufficient to obtain the patterns, in which the degree of polarization feature is less than 1%. If the medium is highly absorptive, more expansion terms are required to obtain the diffusion patterns. The examples of simulated radiance and polarization patterns for Rayleigh scattering, Henyey-Greenstein-Rayleigh scattering, and haze L and cloud C1 scattering, defined by Deirmendjian, are calculated.

  4. Interior radiances in optically deep absorbing media. 3: Scattering from Haze L

    NASA Technical Reports Server (NTRS)

    Kattawar, G. W.; Plass, G. N.

    1974-01-01

    The interior radiances are calculated within an optically deep absorbing medium scattering according to the Haze L phase function. The dependence on the solar zenith angle, the single scattering albedo, and the optical depth within the medium is calculated by the matrix operator method. The development of the asymptotic angular distribution of the radiance in the diffusion region is illustrated through a number of examples; it depends only on the single scattering albedo and on the phase function for single scattering. The exact values of the radiance in the diffusion region are compared with values calculated from the approximate equations proposed by Van de Hulst. The variation of the radiance near the lower boundary of an optically thick medium is illustrated with examples. The attenuation length is calculated for various single scattering albedos and compared with the corresponding values for Rayleigh scattering. The ratio of the upward to the downward flux is found to be remarkably constant within the medium. The heating rate is calculated and found to have a maximum value at an optical depth of two within a Haze L layer when the sun is at the zenith.

  5. Spatial characteristics of airglow and solar-scatter radiance from the earth's atmosphere

    SciTech Connect

    Huguenin, R.; Wohlers, R.; Weinberg, M.; Huffman, R.; Eastes, R.

    1989-08-09

    Data measured by the Polar BEAR/AIRS UV Experiment were processed to extract spatial-radiance characteristics. Photometer-mode 1304A dayside data measured on Julian Day 219, 1987, near mid-day were analyzed. The spatial structure of thermospheric dayside radiance at 1304A appeared to be controlled principally by turbulence over spatial scales of 10 million - 100 meters, with modifications imposed by Rayleigh-scattering effects and magnetospherically forced phenomena. Spatial structure can be adequately modeled fractally, using dimensions based on Kolmogorov formalism modified by the Rayleigh scattering phase function. Mean radiance can be modeled using existing models of radiant intensity, resonance scattering, and absorption combined with thermospheric composition and general circulation models, such as MSIS-83, scaled to the mean and RHS intensities measured by Polar BEAR. The results can be incorporated in a background radiance simulation model that will provide a means for testing and refining phenomenological models of the structured earth background. This will be important not only for improving physical and chemical models of atmospheric features and processes, but it will allow parametric predictions of spatial structure and clutter to be developed for sensor applications.

  6. Bidirectional reflectance of oceanic waters: A comparison of modeled and measured upward radiance fields

    NASA Technical Reports Server (NTRS)

    Morel, Andre; Voss, Kenneth J.; Gentili, Bernard

    1995-01-01

    The bidirectional reflectance of oceanic waters is conveniently described in a normalized way by forming the ratio of the upwelling irradiance E(sub u) to any upwelling radiance L(sub u)(theta prime, phi). This ratio, Q (theta prime, theta(sub 0), (phi(sub 0) - phi), where theta prime, phi are the nadir and azimuth angles for the upward radiance and theta(sub 0), phi(sub 0) are the zenith and azimuth angles of the Sun, has been determined from measurements at sea and computed via Monte Carlo simulations using the inherent optical properties measured in the field and appropriate boundary conditions (clear sky, no wind, varying Sun angle). Experimental ad computed Q values are in excellent agreement. This successful comparison confirms the importance of the bidirectional character of ocean reflectance, already pointed out from a purely numerical approach without field validation, and corroborates the extended range of the Q variations. The later point is of importance when interpreting the marine signals detected by an ocean color satellite-borne sensor. The validation is extended by considering the historical data for the radiance distributions in Lake Pend Oreille determined at various depths. The closure issue in ocean optics is examined by solving the direct problem of radiative transfer and through a model-data comparison in terms of radiance field.

  7. -30° C to 960° C Variable Temperature Blackbody (VTBB) Radiance Temperature Calibration Facility

    NASA Astrophysics Data System (ADS)

    Yuan, Z.; Wang, J.; Hao, X.; Wang, T.; Dong, W.

    2015-12-01

    A blackbody radiance temperature calibration facility (RTCF) has recently been established at the National Institute of Metrology, China, offering calibration and verification services for variable temperature blackbody (VTBB) radiation sources. The RTCF includes reference VTBBs in the range of -30° C to 960° C and consists of a stirred liquid bath blackbody of -30° C to 80° C and water, cesium, and sodium heat-pipe blackbodies spanning 50° C to 960° C. In addition, the facility is equipped with a set of radiation thermometers with different working wavelengths (or wavebands); these thermometers are used to transfer radiance temperatures from the reference to customers' VTBBs. Cavities with V-notch grooves in the inner surface have an estimated emissivity from 0.99986 to 0.99994. The temperature control stability and temperature uniformity of VTBBs are characterized. Furthermore, we test the difference between a cavity and thermometer well temperatures and compare the radiance temperatures of the Cs and Na heat-pipe blackbodies. The expanded uncertainty (k = 2) of VTBBs' radiance temperatures at 10 \\upmu m (8 \\upmu m to 14 \\upmu m) is evaluated from 0.016° C to 0.23° C. The facility has been used to calibrate and characterize customers' VTBBs.

  8. Structures observed on the spot radiance fields during the FIRE experiment

    NASA Technical Reports Server (NTRS)

    Seze, Genevieve; Smith, Leonard; Desbois, Michel

    1990-01-01

    Three Spot images taken during the FIRE experiment on stratocumulus are analyzed. From this high resolution data detailed observations of the true cloud radiance field may be made. The structure and inhomogeneity of these radiance fields hold important implications for the radiation budget, while the fine scale structure in radiance field provides information on cloud dynamics. Wieliki and Welsh, and Parker et al., have quantified the inhomogeneities of the cumulus clouds through a careful examination of the distribution of cloud (and hole) size as functions of an effective cloud diameter and radiance threshold. Cahalan (1988) has compared for different cloud types of (stratocumulus, fair weather cumulus, convective clouds in the ITCZ) the distributions of clouds (and holes) sizes, the relation between the size and the perimeter of these clouds (and holes), and examining the possibility of scale invariance. These results are extended from LANDSAT resolution (57 m and 30 m) to the Spot resolution (10 m) resolution in the case of boundary layer clouds. Particular emphasis is placed on the statistics of zones of high and low reflectivity as a function of a threshold reflectivity.

  9. [Research on absolute calibration of sun channel of sun photometer using laser raster scanning method].

    PubMed

    Xu, Wen-Bin; Li, Jian-Jun; Zheng, Xiao-Bing

    2013-01-01

    In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3.75%. In the last, the uncertainties of calibration were evaluated and reached to 2.06%. The principle feasibility of the new method was validated.

  10. Deriving a relationship between the radiative power and the SWIR radiance for Gas Flares

    NASA Astrophysics Data System (ADS)

    Caseiro, Alexandre; Kaiser, Johannes W.; Heil, Angelika; Rücker, Gernot; Tiemann, Joachim; Leimbach, David

    2016-04-01

    Flaring occurs in many regions and is a source of black carbon (BC) globally, among other pollutants. At higher latitudes, flaring is the main source of BC which, upon deposition on snow, lowers its albedo. Therefore, knowing the location and emissions of flares would be a valuable input to climate models. The main goal of this work is to derive a working relationship between Shortwave Infrared at 1.6 μm (SWIR) radiance and Radiative Power (RP). Such a relationship will be helpful in the processing chain use to determine the emissions from gas flares for upcoming instruments, such as the SLSTR on Sentinel-3. In order to derive the relationship between RP and SWIR, RP assigned to Gas Flares (GFs) observed by the small German satellite BIRD is related to the SWIR radiance time series as observed by AATSR at that location in a temporal window of ± 2 months around the BIRD observation. The SWIR signal was retrieved from the AATSR pixel where the GF was identified by BIRD. For each observation, the signal is considered as being above the detection limit if its value is above three times the background standard deviation. The background is a window of approximately 10 × 10 km2 around the GF location pixel. The reported SWIR radiance value is the radiance signal minus the background average. The SWIR radiance signal thus retrieved shows a large variation throughout the time window considered. Such a variation evidences temporal variation in the flaring intensity, possibly GFs are either inactive or active, with varying levels of intensity, throughout time. In a subsequent step, it is also determined whether the radiance at the GF location pixel is a local maximum (after excluding other possible GF locations within the surroundings). Then, a new average and standard deviation for each GF may be constructed, more representative of when the GF is actually on. Those figures are then compared to a normalized RP. The normalization is necessary because the BIRD fire processor

  11. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  12. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  13. Preschoolers' Success at Coding Absolute Size Values.

    ERIC Educational Resources Information Center

    Russell, James

    1980-01-01

    Forty-five 2-year-old and forty-five 3-year-old children coded relative and absolute sizes using 1.5-inch, 6-inch, and 18-inch cardboard squares. Results indicate that absolute coding is possible for children of this age. (Author/RH)

  14. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  15. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  16. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  17. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  18. Vertical structure and optical properties of Titan's aerosols from radiance measurements made inside and outside the atmosphere

    NASA Astrophysics Data System (ADS)

    Doose, Lyn R.; Karkoschka, Erich; Tomasko, Martin G.; Anderson, Carrie M.

    2016-05-01

    Prompted by the detection of stratospheric cloud layers by Cassini's Composite Infrared Spectrometer (CIRS; see Anderson, C.M., Samuelson, R.E. [2011]. Icarus 212, 762-778), we have re-examined the observations made by the Descent Imager/Spectral Radiometer (DISR) in the atmosphere of Titan together with two constraints from measurements made outside the atmosphere. No evidence of thin layers (<1 km) in the DISR image data sets is seen beyond the three previously reported layers at 21 km, 11 km, and 7 km by Karkoschka and Tomasko (Karkoschka, E., Tomasko, M.G. [2009]. Icarus 199, 442-448). On the other hand, there is evidence of a thicker layer centered at about 55 km. A rise in radiance gradients in the Downward-Looking Visible Spectrometer (DLVS) data below 55 km indicates an increase in the volume extinction coefficient near this altitude. To fit the geometric albedo measured from outside the atmosphere the decrease in the single scattering albedo of Titan's aerosols at high altitudes, noted in earlier studies of DISR data, must continue to much higher altitudes. The altitude of Titan's limb as a function of wavelength requires that the scale height of the aerosols decrease with altitude from the 65 km value seen in the DISR observations below 140 km to the 45 km value at higher altitudes. We compared the variation of radiance with nadir angle observed in the DISR images to improve our aerosol model. Our new aerosol model fits the altitude and wavelength variations of the observations at small and intermediate nadir angles but not for large nadir angles, indicating an effect that is not reproduced by our radiative transfer model. The volume extinction profiles are modeled by continuous functions except near the enhancement level near 55 km altitude. The wavelength dependence of the extinction optical depth is similar to earlier results at wavelengths from 500 to 700 nm, but is smaller at shorter wavelengths and larger toward longer wavelengths. A Hapke

  19. Assessment of a bidirectional reflectance distribution correction of above-water and satellite water-leaving radiance in coastal waters.

    PubMed

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

    2012-01-10

    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. This confirms the advantages of the proposed model over the current

  20. Spectral Predictors

    SciTech Connect

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  1. Polarization impacts on the water-leaving radiance retrieval from above-water radiometric measurements.

    PubMed

    Harmel, Tristan; Gilerson, Alexander; Tonizzo, Alberto; Chowdhary, Jacek; Weidemann, Alan; Arnone, Robert; Ahmed, Sam

    2012-12-10

    Above-water measurements of water-leaving radiance are widely used for water-quality monitoring and ocean-color satellite data validation. Reflected skylight in above-water radiometry needs to be accurately estimated prior to derivation of water-leaving radiance. Up-to-date methods to estimate reflection of diffuse skylight on rough sea surfaces are based on radiative transfer simulations and sky radiance measurements. But these methods neglect the polarization state of the incident skylight, which is generally highly polarized. In this paper, the effects of polarization on the sea surface reflectance and the subsequent water-leaving radiance estimation are investigated. We show that knowledge of the polarization field of the diffuse skylight significantly improves above-water radiometry estimates, in particular in the blue part of the spectrum where the reflected skylight is dominant. A newly developed algorithm based on radiative transfer simulations including polarization is described. Its application to the standard Aerosol Robotic Network-Ocean Color and hyperspectral radiometric measurements of the 1.5-year dataset acquired at the Long Island Sound site demonstrates the noticeable importance of considering polarization for water-leaving radiance estimation. In particular it is shown, based on time series of collocated data acquired in coastal waters, that the azimuth range of measurements leading to good-quality data is significantly increased, and that these estimates are improved by more than 12% at 413 nm. Full consideration of polarization effects is expected to significantly improve the quality of the field data utilized for satellite data validation or potential vicarious calibration purposes.

  2. View-angle-dependent AIRS Cloudiness and Radiance Variance: Analysis and Interpretation

    NASA Technical Reports Server (NTRS)

    Gong, Jie; Wu, Dong L.

    2013-01-01

    Upper tropospheric clouds play an important role in the global energy budget and hydrological cycle. Significant view-angle asymmetry has been observed in upper-level tropical clouds derived from eight years of Atmospheric Infrared Sounder (AIRS) 15 um radiances. Here, we find that the asymmetry also exists in the extra-tropics. It is larger during day than that during night, more prominent near elevated terrain, and closely associated with deep convection and wind shear. The cloud radiance variance, a proxy for cloud inhomogeneity, has consistent characteristics of the asymmetry to those in the AIRS cloudiness. The leading causes of the view-dependent cloudiness asymmetry are the local time difference and small-scale organized cloud structures. The local time difference (1-1.5 hr) of upper-level (UL) clouds between two AIRS outermost views can create parts of the observed asymmetry. On the other hand, small-scale tilted and banded structures of the UL clouds can induce about half of the observed view-angle dependent differences in the AIRS cloud radiances and their variances. This estimate is inferred from analogous study using Microwave Humidity Sounder (MHS) radiances observed during the period of time when there were simultaneous measurements at two different view-angles from NOAA-18 and -19 satellites. The existence of tilted cloud structures and asymmetric 15 um and 6.7 um cloud radiances implies that cloud statistics would be view-angle dependent, and should be taken into account in radiative transfer calculations, measurement uncertainty evaluations and cloud climatology investigations. In addition, the momentum forcing in the upper troposphere from tilted clouds is also likely asymmetric, which can affect atmospheric circulation anisotropically.

  3. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  4. Prospects for the Moon as an SI-Traceable Absolute Spectroradiometric Standard for Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Cramer, C. E.; Stone, T. C.; Lykke, K.; Woodward, J. T.

    2015-12-01

    The Earth's Moon has many physical properties that make it suitable for use as a reference light source for radiometric calibration of remote sensing satellite instruments. Lunar calibration has been successfully applied to many imagers in orbit, including both MODIS instruments and NPP-VIIRS, using the USGS ROLO model to predict the reference exoatmospheric lunar irradiance. Sensor response trending was developed for SeaWIFS with a relative accuracy better than 0.1 % per year with lunar calibration techniques. However, the Moon rarely is used as an absolute reference for on-orbit calibration, primarily due to uncertainties in the ROLO model absolute scale of 5%-10%. But this limitation lies only with the models - the Moon itself is radiometrically stable, and development of a high-accuracy absolute lunar reference is inherently feasible. A program has been undertaken by NIST to collect absolute measurements of the lunar spectral irradiance with absolute accuracy <1 % (k=2), traceable to SI radiometric units. Initial Moon observations were acquired from the Whipple Observatory on Mt. Hopkins, Arizona, elevation 2367 meters, with continuous spectral coverage from 380 nm to 1040 nm at ~3 nm resolution. The lunar spectrometer acquired calibration measurements several times each observing night by pointing to a calibrated integrating sphere source. The lunar spectral irradiance at the top of the atmosphere was derived from a time series of ground-based measurements by a Langley analysis that incorporated measured atmospheric conditions and ROLO model predictions for the change in irradiance resulting from the changing Sun-Moon-Observer geometry throughout each night. Two nights were selected for further study. An extensive error analysis, which includes instrument calibration and atmospheric correction terms, shows a combined standard uncertainty under 1 % over most of the spectral range. Comparison of these two nights' spectral irradiance measurements with predictions

  5. Spectral emissivity measurements of land-surface materials and related radiative transfer simulations

    NASA Technical Reports Server (NTRS)

    Wan, Z.; Ng, D.; Dozier, J.

    1994-01-01

    Spectral radiance measurements have been made in the laboratory and in the field for deriving spectral emissivities of some land cover samples with a spectroradiometer and an auxiliary radiation source in the wavelength range 2.5-14.5 micrometers. A easy and quick four-step method (four steps to measure the sample and a diffuse reflecting plate surface under sunshine and shadowing conditions, respectively) has been used for simultaneous determination of surface temperature and emissivity. We emphasized in-situ measurements in combination with radiative transfer simulations, and an error analysis for basic assumptions in deriving spectral emissivity of land-surface samples from thermal infrared measurements.

  6. Application of the spectrally integrated Voigt function to line-by-line radiative transfer modelling

    NASA Astrophysics Data System (ADS)

    Quine, B. M.; Abrarov, S. M.

    2013-09-01

    We show that a new approach based on the spectrally integrated Voigt function (SIVF) enables the computation of line-by-line (LBL) radiative transfer at reduced spectral resolution without loss of accuracy. The algorithm provides rapid and accurate computation of area under the Voigt function in a way that preserves spectral radiance and, consequently, radiant intensity. The error analysis we provide shows the high-accuracy of the proposed SIVF approximations. A comparison of the performance of the method with that of the traditional LBL approach is presented. Motivations for the use and advantage of the SIVF as a replacement for conventional line function computations in radiative transfer are discussed.

  7. Design and modeling of spectral-thermal unmixing targets for airborne hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Clare, Phil

    2006-05-01

    Techniques to determine the proportions of constituent materials within a single pixel spectrum are well documented in the reflective (0.4-2.5μm) domain. The same capability is also desirable for the thermal (7-14μm) domain, but is complicated by the thermal contributions to the measured spectral radiance. Atmospheric compensation schemes for the thermal domain have been described along with methods for estimating the spectral emissivity from a spectral radiance measurement and hence the next stage to be tackled is the unmixing of thermal spectral signatures. In order to pursue this goal it is necessary to collect data of well-calibrated targets which will expose the limits of the available techniques and enable more robust methods to be designed. This paper describes the design of a set of ground targets for an airborne hyperspectral imager, which will test the effectiveness of available methods. The set of targets include panels to explore a number of difficult scenarios such as isothermal (different materials at identical temperature), isochromal (identical materials, but at differing temperatures), thermal adjacency and thermal point sources. Practical fabrication issues for heated targets and selection of appropriate materials are described. Mathematical modelling of the experiments has enabled prediction of at-sensor measured radiances which are used to assess the design parameters. Finally, a number of useful lessons learned during the fielding of these actual targets are presented to assist those planning future trials of thermal hyperspectral sensors.

  8. Some paradoxes, errors, and resolutions concerning the spectral optimization of human vision

    NASA Astrophysics Data System (ADS)

    Soffer, Bernard H.; Lynch, David K.

    1999-11-01

    The peak brightness of the solar spectrum is in the green when plotted in wavelength units. It peaks in the near-infrared when plotted in frequency units. Therefore the oft-quoted notion that evolution led to an optimized eye whose sensitivity peaks where there is most available sunlight is misleading and erroneous. The confusion arises when density distribution functions like the spectral radiance are compared with ordinary functions like the sensitivity of the eye. Spectral radiance functions, excepting very narrow ones, can change peak positions greatly when transformed from wavelength to frequency units, but sensitivity functions do not. Expressing the spectral radiance in terms of photons per second, rather than power, also causes a change in the shape and peak of the distribution, even keeping the choice of bandwidth units fixed. The confusion arising from comparing simple functions to distribution functions occurs in many parts of the scientific and engineering literature aside from vision, and some examples are given. The eye does not appear to be optimized for detection of the available sunlight, including the surprisingly large amount of infrared radiation in the environment. The color sensitivity of the eye is discussed in terms of the spectral properties and the photo and chemical stability of available biological materials. It is likely that we are viewing the world with a souvenir of the human evolutionary voyage.

  9. Vacuum ultraviolet spectral emission properties of Ga, In and Sn droplet-based laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Brandstätter, Markus; Abhari, Reza S.

    2016-08-01

    The Emission Spectra of gallium, indium and tin droplet-based laser produced plasmas are presented in the Vacuum Ultraviolet (VUV) emission range from 30 nm to 160 nm. The Ga ion transitions are investigated in detail as a function of background pressure level and laser irradiance. Different wavelength emission regions were detected according to the level of background gas. At short wavelengths (i.e. 30-50 nm) the line emission from the higher charge states is reduced with increasing pressure, while at longer wavelengths (i.e. 100-160 nm) the trend is inverted, as the plasma emission intensity of the lower charge states increases with higher background gas pressure level. The emitted lines are fitted with Voigt profiles to determine the electron density. The electron temperature is obtained from a fit based on the Planck distribution. These estimations are then used to identify the relevant processes that lead to the different charge state emissions as a function of background gas. Langmuir Probe measurements are also reported for evaluating the ion kinetic energy as a function of background gas. The gallium spectra are calibrated in units of spectral radiance, together with spectra from indium and tin. This calibration allows absolute power estimations from the light source in the VUV region. The presented experimental results are relevant as fundamental plasma emission spectroscopic measurements in an almost unexplored wavelength region as well as for applications such as Extreme Ultraviolet Lithography to determine the so-called Out-of-Band (OoB) radiation emission and for metrology applications for future inspection tools.

  10. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 1: Simple forward model

    NASA Astrophysics Data System (ADS)

    Eckermann, S. D.; Wu, D. L.

    2006-08-01

    Using a simplified model of in-orbit radiance acquisition by the Advanced Microwave Sounding Unit (AMSU-A), we derive three-dimensional temperature weighting functions for Channel 9 measurements (peaking at ~60-90 hPa) at all 30 cross-track beam positions and use them to investigate the sensitivity of these radiances to gravity waves. The vertical widths of the weighting functions limit detection to waves with vertical wavelengths of ≳10 km, with slightly better vertical wavelength sensitivity at the outermost scan angles due to the limb effect. Fourier Transforms of two-dimensional cross-track weighting functions reveal optimal sensitivity to cross-track wavelengths at the near-nadir scan angles, where horizontal measurement footprints are smallest. This sensitivity is greater for the AMSU-A on the Aqua satellite than for the identical instruments on the NOAA meteorological satellites, due to a lower orbit altitude and thus smaller horizontal footprints from antenna spreading. Small cross-track asymmetries in the radiance response to gravity waves are found that peak at the mid-range scan angles, with more symmetric responses at near-nadir and far off-nadir scan angles. Three-dimensional simulations show gravity wave oscillations imaged in horizontal AMSU-A radiance maps swept out by the scan pattern and satellite motion. A distorting curvature is added to imaged wave phase lines due to vertical variations in weighting function peaks with cross-track scan angle. This wave distortion is analogous to the well-known "limb darkening" and "limb brightening" of microwave radiances acquired from purely vertical background temperature profiles by cross-track scanners. Waves propagating along track are more visible in these images at the outermost scan angles than those propagating cross track, due to oversampling and narrower widths of the horizontal measurement footprints in the along track direction. Based on nominal noise floors and representative lower stratospheric

  11. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 1: simple forward model

    NASA Astrophysics Data System (ADS)

    Eckermann, S. D.; Wu, D. L.

    2006-03-01

    Using a simplified model of in-orbit radiance acquisition by the Advanced Microwave Sounding Unit (AMSU-A), we derive three-dimensional temperature weighting functions for Channel 9 measurements (peaking at ~60-90 hPa) at all 30 cross-track beam positions and use them to investigate the sensitivity of these radiances to gravity waves. The vertical widths of the weighting functions limit detection to waves with vertical wavelengths of ≳10 km, with slightly better vertical wavelength sensitivity at the outermost scan angles due to the limb effect. Fourier Transforms of two-dimensional cross-track weighting functions reveal optimal sensitivity to cross-track wavelengths at the near-nadir scan angles, where horizontal measurement footprints are smallest. This sensitivity is greater for the AMSU-A on the Aqua satellite than for the identical instruments on the NOAA meteorological satellites, due to a lower orbit altitude and thus smaller horizontal footprints from antenna spreading. Small cross-track asymmetries in the radiance response to gravity waves are found that peak at the mid-range scan angles, with more symmetric responses at near-nadir and far off-nadir scan angles. Three-dimensional simulations show gravity wave oscillations imaged in horizontal AMSU-A radiance maps swept out by the scan pattern and satellite motion. A distorting curvature is added to imaged wave phase lines due to vertical variations in weighting function peaks with cross-track scan angle. This wave distortion is analogous to the well-known ''limb darkening'' and ''limb brightening'' of microwave radiances acquired from purely vertical background temperature profiles by cross-track scanners. Waves propagating along track are more visible in these images at the outermost scan angles than those propagating cross track, due to oversampling and narrower widths of the horizontal measurement footprints in the along track direction. Based on nominal noise floors and representative lower

  12. High spectral resolution measurements for the ARM Program. Year two technical progress report, March 15, 1991--March 15, 1992

    SciTech Connect

    Revercomb, H.E.

    1992-05-22

    This report focuses on the design and fabrication of high spectral resolution FTIR (Fourier Transform Infrared) instrumentation for the CART sites of the Atmospheric Radiation Measurement (ARM) Program. The ultimate objective of this grant is to develop three different types of instruments, named the AERI, AERI-X, and SORT. The Atmospheric Emitted Radiance Interferometer (AERI) is the simplest. It will be available for early deployment at the first ARM site and will be deployable at several locations in the extended network to give horizontal coverage. The AERI will be an 0.5 cm{sup {minus}1} resolution instrument, which measures accurately calibrated radiance spectra for radiation studies and for remote sensing of atmospheric state variables. The AERI-X and the SORTI are higher spectral resolution instruments for obtaining the highest practical resolution for spectroscopy at the ARM central sites. The AERI-X, like the AERI will measure atmospheric emitted radiance, but with resolutions as high as 0.1 cm{sup {minus}1}. The Solar Radiance Transmission Interferometer will measure the total transmission of the atmosphere by tracking the sun through changes in atmospheric air mass. The large solar signal makes it practical for this instrument to offer the ultimate in spectral resolution, about 0.002 cm{sup {minus}1}.

  13. Quantum Efficient Detectors for Use in Absolute Calibration

    NASA Technical Reports Server (NTRS)

    Faust, Jessica; Eastwood, Michael; Pavri, Betina; Raney, James

    1998-01-01

    The trap or quantum efficient detector has a quantum efficiency of greater than 0.98 for the region from 450 to 900 nm. The region of flattest response is from 600 to 900 nm. The QED consists of three windowless Hamamatsu silicon detectors. The QED was mounted below AVIRIS to monitor the Spectralon panel for changes in radiance during radiometric calibration. The next step is to permanently mount the detector to AVIRIS and monitor the overall radiance of scenes along with calibration.

  14. An alternate algorithm for correction of the scanning multichannel microwave radiometer polarization radiances using Nimbus-7 observed data

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Cavalieri, D. J.; Soule, H. V.

    1980-01-01

    The manner in which Nimbus-7 scanning multichannel microwave radiometer (SMMR) scan radiance data was used to determine its operational characteristics is described. The predicted SMMR scan radiance was found to be in disagreement at all wavelengths with a large area of average measured ocean radiances. A modified model incorporating a different phase shift for each of the SMMR horizontal and vertical polarization channels was developed and found to provide good data correlation. Additional study is required to determine the validity and accuracy of this model.

  15. Mars 1064-nm Spectral Radiance Measurements from the Receiver Noise Response of the Mars Orbiter Laser Altimeter

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Neumann, Gregory A.; Abshire, James B.; Zuber, Maria T.

    2005-01-01

    The Mars Orbiter Laser Altimeter not only provides surface topography from the laser pulse time-of-flight, but also two radiometric measurements, the active measurement of transmitted and reflected laser pulse energy, and the passive measurement of reflected solar illumination. The passive radiometry measurement is accomplished in a novel fashion by monitoring the noise density at the output of the photodetector and solving for the amount of background light. The passive radiometry measurements provide images of Mars at 1064-nm wavelength over a 2 nm bandwidth with sub-km spatial resolution and with 2% or better precision under full illumination. We describe in this paper the principle of operation, the receiver mathematical model, its calibration, and performance assessment from sample measurement data.

  16. Modeling of spectral signatures of littoral waters

    NASA Astrophysics Data System (ADS)

    Haltrin, Vladimir I.

    1997-12-01

    The spectral values of remotely obtained radiance reflectance coefficient (RRC) are compared with the values of RRC computed from inherent optical properties measured during the shipborne experiment near the West Florida coast. The model calculations are based on the algorithm developed at the Naval Research Laboratory at Stennis Space Center and presented here. The algorithm is based on the radiation transfer theory and uses regression relationships derived from experimental data. Overall comparison of derived and measured RRCs shows that this algorithm is suitable for processing ground truth data for the purposes of remote data calibration. The second part of this work consists of the evaluation of the predictive visibility model (PVM). The simulated three-dimensional values of optical properties are compared with the measured ones. Preliminary results of comparison are encouraging and show that the PVM can qualitatively predict the evolution of inherent optical properties in littoral waters.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  19. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  20. The Simplicity Argument and Absolute Morality

    ERIC Educational Resources Information Center

    Mijuskovic, Ben

    1975-01-01

    In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

  1. Operational calibration of the METEOSAT water vapor channel by calculated radiances.

    PubMed

    Schmetz, J

    1989-08-01

    A method is presented for calibrating the water vapor channel (5.7-7.1 microm) of the geostationary meteorological satellite METEOSAT by radiative transfer calculations. Radiances are calculated from the temperature and moisture profiles of conventional radiosondes and linearly related to collocated satellite measured digital counts. Collocations are considered only for areas with neither medium nor high level cloud. Radiosonde data are routinely received twice per day (1200 and 2400 UT). Radiosonde profiles from an 8-day period in May 1988, and simultaneous Meteosat-2 water vapor measurements are analyzed. The total of 340 collocations provides a calibration coefficient with a precision of 2% assuming a 95% confidence. A preliminary analysis of calibration coefficients of the recently launched METEOSAT-3 shows a significant increase of 6% over a period of 48 days in Sept./Oct. 1988. The calibrated water vapor radiances are operationally used to estimate the upper tropospheric humidity field and to correct the height assignment of semitransparent clouds.

  2. Radiance and polarization of multiple scattered light from haze and clouds.

    PubMed

    Kattawar, G W; Plass, G N

    1968-08-01

    The radiance and polarization of multiple scattered light is calculated from the Stokes' vectors by a Monte Carlo method. The exact scattering matrix for a typical haze and for a cloud whose spherical drops have an average radius of 12 mu is calculated from the Mie theory. The Stokes' vector is transformed in a collision by this scattering matrix and the rotation matrix. The two angles that define the photon direction after scattering are chosen by a random process that correctly simulates the actual distribution functions for both angles. The Monte Carlo results for Rayleigh scattering compare favorably with well known tabulated results. Curves are given of the reflected and transmitted radiances and polarizations for both the haze and cloud models and for several solar angles, optical thicknesses, and surface albedos. The dependence on these various parameters is discussed.

  3. Time-cumulated visible and infrared radiance histograms used as descriptors of surface and cloud variations

    NASA Technical Reports Server (NTRS)

    Seze, Genevieve; Rossow, William B.

    1991-01-01

    The spatial and temporal stability of the distributions of satellite-measured visible and infrared radiances, caused by variations in clouds and surfaces, are investigated using bidimensional and monodimensional histograms and time-composite images. Similar analysis of the histograms of the original and time-composite images provides separation of the contributions of the space and time variations to the total variations. The variability of both the surfaces and clouds is found to be larger at scales much larger than the minimum resolved by satellite imagery. This study shows that the shapes of these histograms are distinctive characteristics of the different climate regimes and that particular attributes of these histograms can be related to several general, though not universal, properties of clouds and surface variations at regional and synoptic scales. There are also significant exceptions to these relationships in particular climate regimes. The characteristics of these radiance histograms provide a stable well defined descriptor of the cloud and surface properties.

  4. Process of preparing metal parts to be heated by means of infrared radiance

    DOEpatents

    Mayer, Howard Robinson; Blue, Craig A.

    2009-06-09

    A method for preparing metal for heating by infrared radiance to enable uniform and consistent heating. The surface of one or more metal parts, such as aluminum or aluminum alloy parts, is treated to alter the surface finish to affect the reflectivity of the surface. The surface reflectivity is evaluated, such as by taking measurements at one or more points on the surface, to determine if a desired reflectivity has been achieved. The treating and measuring are performed until the measuring indicates that the desired reflectivity has been achieved. Once the treating has altered the surface finish to achieve the desired reflectivity, the metal part may then be exposed to infrared radiance to heat the metal part to a desired temperature, and that heating will be substantially consistent throughout by virtue of the desired reflectivity.

  5. Laboratory upwelled radiance and reflectance spectra of Kerr reservoir sediment waters

    NASA Technical Reports Server (NTRS)

    Witte, W. G.; Whitlock, C. H.; Morris, W. D.; Gurganus, E. A.

    1982-01-01

    Reflectance, chromaticity, and several other physical and chemical properties were measured for various water mixtures of bottom sediments taken from two sites at Kerr Reservoir, Virginia. Mixture concentrations ranged from 5 to 1000 ppm by weight of total suspended solids (TSS) in filtered deionized tap water. The two sets of radiance and reflectance spectra obtained were similar in shape and magnitude for comparable values of TSS. Upwelled reflectance was observed to be a nonlinear function of TSS with the degree of curvature a function of wavelength. Sediment from the downstream site contained a greater amount of particulate organic carbon than from the upstream site. No strong conclusions can be made regarding the effects of this difference on the radiance and reflectance spectra. Near-infrared wavelengths appear useful for measuring highly turbid water with concentrations up to 1000 ppm or more. Chromaticity characteristics do not appear useful for monitoring sediment loads above 150 ppm.

  6. An imaging spectro-polarimeter for measuring hemispherical spectrally resolved down-welling sky polarization

    NASA Astrophysics Data System (ADS)

    Chenault, David B.; Pezzaniti, J. L.; Roche, Michael; Hyatt, Brian

    2016-05-01

    A full sky imaging spectro-polarimeter has been developed that measures spectrally resolved (~2.5 nm resolution) radiance and polarization (𝑠0, 𝑠1, 𝑠2 Stokes Elements) of natural sky down-welling over approximately 2π sr between 400nm and 1000nm. The sensor is based on a scanning push broom hyperspectral imager configured with a continuously rotating polarizer (sequential measurement in time polarimeter). Sensor control and processing software (based on Polaris Sensor Technologies Grave' camera control software) has a straight-forward and intuitive user interface that provides real-time updated sky down-welling spectral radiance/polarization maps and statistical analysis tools.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Design Studies for a Far Infrared Absolute Spectrometer for the Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Johnson, N. J. E.

    1980-01-01

    Unrelenting symmetry of design is required to assure the thermal balance of a cryogenically cooled, rapid scan interferometer spectrometer to be mounted in vacuum with the Cosmic Background Explorer liquid helium dewar. The instrument receives inputs from Winston cone optical flux collectors, one open to space and a second coupled to a black body reference source. A differential instrument, the spectrometer produces outputs corresponding to the Fourier transform of the spectral radiance difference between the two inputs. The two outputs are sensed by four detectors, two optimized for shorter wavelength response, and two optimized for longer wavelengths. The optical design, detector and signal channel, system sensitivity, mechanics, thermal control and cryogenics, electronics and power systems, command and control, calibration, system test requirements, and the instrument interface are discussed. Recommendations for continued work are indicated for the superconducting reflective horns, the motor bearing and drive, and design detail.

  9. Using Ground Spectral Irradiance for Model Correction of AVIRIS Data

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Heidebrecht, Kathleen B.; Kindel, Bruce; Boardman, Joseph W.

    1998-01-01

    Over the last decade a series of techniques has been developed to correct hyperspectral imaging sensor data to apparent surface reflectance. The techniques range from the empirical line method that makes use of ground target measurements to model-based methods such as ATREM that derive parameters from the data themselves to convert radiance to reflectance, and combinations of the above. Here we describe a technique that combines ground measurements of spectral irradiance with existing radiative transfer models to derive the model equivalent of an empirical line method correction without the need for uniform ground targets of different reflectance.

  10. Basis for spectral curvature algorithms in remote sensing of chlorophyll

    NASA Technical Reports Server (NTRS)

    Campbell, J. W.; Esaias, W. E.

    1983-01-01

    A simple, empirically derived algorithm for estimating oceanic chlorophyll concentrations from spectral radiances measured by a low-flying spectroradiometer has proved highly successful in field experiments in 1980-82. The sensor used was the Multichannel Ocean Color Sensor, and the originator of the algorithm was Grew (1981). This paper presents an explanation for the algorithm based on the optical properties of waters containing chlorophyll and other phytoplankton pigments and the radiative transfer equations governing the remotely sensed signal. The effects of varying solar zenith, atmospheric transmittance, and interfering substances in the water on the chlorophyll algorithm are characterized, and applicability of the algorithm is discussed.

  11. Consistency of CERES Radiances and Fluxes from Aqua and Suomi-NPP

    NASA Technical Reports Server (NTRS)

    Su, Wenying; Liang, Lusheng; Miller, Walter; Loeb, Norman

    2015-01-01

    The Clouds and Earth's Radiant Energy System (CERES) instruments on board Terra, Aqua, and Suomi-NPP have been providing data products critical to advancing our understanding of the effects of clouds and aerosols on radiative energy within the Earth-atmosphere system. The CERES instrument consists of a threechannel broadband scanning radiometer. The scanning radiometer measures radiances in shortwave (SW, 0.3-5 micron), window (WN, 8-12 micron), and total (0.3-200 micron) channels. The longwave (LW) component is derived as the difference between total and SW channels. These measured radiances at a given sun-Earthsatellite geometry are converted to outgoing reflected solar and emitted thermal TOA radiative fluxes by using CERES scene-type dependent angular distribution models (ADMs). The CERES instruments must remain radiometrically stable and correctly inter-calibrated to accurately capture changes in Earth"s radiation budget from interannual to decadal timescales. This presentation will focus on comparisons between collocated radiance measurements from CERES instruments on Aqua and on Suomi-NPP. As we do not have a set of ADMs that is constructed specifically for the CERES instrument on Suomi-NPP, CERES Aqua ADMs are used to invert fluxes from radiance measurements on Suomi-NPP. But the CERES Aqua footprint size is smaller than the CERES Suomi-NPP footprint size and the scene identifications provided by MODIS and VIIRS can also be different from each other. Will using Aqua ADMs for Suomi-NPP flux inversion increase the flux uncertainty? We will examine the deseasonalized flux anomaly time series using Aqua data alone and using combined Aqua and Suomi-NPP data. We will also present a simulation study to assess the Suomi-NPP flux uncertainty from using Aqua ADMs for the flux inversion.

  12. Neural network method to correct bidirectional effects in water-leaving radiance.

    PubMed

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

    2016-01-01

    Ocean color algorithms that rely on "atmospherically corrected" nadir water-leaving radiances to infer information about marine constituents such as the chlorophyll concentration depend on a reliable method to convert the angle-dependent measured radiances from the observation direction to the nadir direction. It is also important to convert the measured radiances to the nadir direction when comparing and merging products from different satellite missions. The standard correction method developed by Morel and coworkers requires knowledge of the chlorophyll concentration. Also, the standard method was developed based on the Case 1 (open ocean) assumption, which makes it unsuitable for Case 2 situations such as turbid coastal waters. We introduce a neural network method to convert the angle-dependent water-leaving radiance (or the corresponding remote sensing reflectance) from the observation direction to the nadir direction. This method relies on neither an "atmospheric correction" nor prior knowledge of the water constituents or the inherent optical properties. It directly converts the remote sensing reflectance from an arbitrary slanted viewing direction to the nadir direction by using a trained neural network. This method is fast and accurate, and it 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 Case 1 and Case 2 waters. In Case 1 or chlorophyll-dominated waters, our neural network method produces corrections similar to those of the standard method. In Case 2 waters, especially sediment-dominated waters, a significant improvement was obtained compared to the standard method.

  13. Spectral calibration of hyperspectral imagery using atmospheric absorption features.

    PubMed

    Guanter, Luis; Richter, Rudolf; Moreno, José

    2006-04-01

    One of the initial steps in the preprocessing of remote sensing data is the atmospheric correction of the at-sensor radiance images, i.e., radiances recorded at the sensor aperture. Apart from the accuracy in the estimation of the concentrations of the main atmospheric species, the retrieved surface reflectance is also influenced by the spectral calibration of the sensor, especially in those wavelengths mostly affected by gaseous absorptions. In particular, errors in the surface reflectance appear when a systematic shift in the nominal channel positions occurs. A method to assess the spectral calibration of hyperspectral imaging spectrometers from the acquired imagery is presented in this paper. The fundamental basis of the method is the calculation of the value of the spectral shift that minimizes the error in the estimates of surface reflectance. This is performed by an optimization procedure that minimizes the deviation between a surface reflectance spectrum and a smoothed one resulting from the application of a low-pass filter. A sensitivity analysis was performed using synthetic data generated with the MODTRAN4 radiative transfer code for several values of the spectral shift and the water vapor column content. The error detected in the retrieval is less than +/- 0.2 nm for spectral shifts smaller than 2 nm, and less than +/- 1.0 nm for extreme spectral shifts of 5 nm. A low sensitivity to uncertainties in the estimation of water vapor content was found, which reinforces the robustness of the algorithm. The method was successfully applied to data acquired by different hyperspectral sensors. PMID:16608005

  14. RADIANCE: An automated, enterprise-wide solution for archiving and reporting CT radiation dose estimates.

    PubMed

    Cook, Tessa S; Zimmerman, Stefan L; Steingall, Scott R; Maidment, Andrew D A; Kim, Woojin; Boonn, William W

    2011-01-01

    There is growing interest in the ability to monitor, track, and report exposure to radiation from medical imaging. Historically, however, dose information has been stored on an image-based dose sheet, an arrangement that precludes widespread indexing. Although scanner manufacturers are beginning to include dose-related parameters in the Digital Imaging and Communications in Medicine (DICOM) headers of imaging studies, there remains a vast repository of retrospective computed tomographic (CT) data with image-based dose sheets. Consequently, it is difficult for imaging centers to monitor their dose estimates or participate in the American College of Radiology (ACR) Dose Index Registry. An automated extraction software pipeline known as Radiation Dose Intelligent Analytics for CT Examinations (RADIANCE) has been designed that quickly and accurately parses CT dose sheets to extract and archive dose-related parameters. Optical character recognition of information in the dose sheet leads to creation of a text file, which along with the DICOM study header is parsed to extract dose-related data. The data are then stored in a relational database that can be queried for dose monitoring and report creation. RADIANCE allows efficient dose analysis of CT examinations and more effective education of technologists, radiologists, and referring physicians regarding patient exposure to radiation at CT. RADIANCE also allows compliance with the ACR's dose reporting guidelines and greater awareness of patient radiation dose, ultimately resulting in improved patient care and treatment.

  15. Impact of horizontal and vertical localization scales on microwave sounder SAPHIR radiance assimilation

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, C.; Balaji, C.

    2016-05-01

    In the present study, the effect of horizontal and vertical localization scales on the assimilation of direct SAPHIR radiances is studied. An Artificial Neural Network (ANN) has been used as a surrogate for the forward radiative calculations. The training input dataset for ANN consists of vertical layers of atmospheric pressure, temperature, relative humidity and other hydrometeor profiles with 6 channel Brightness Temperatures (BTs) as output. The best neural network architecture has been arrived at, by a neuron independence study. Since vertical localization of radiance data requires weighting functions, a ANN has been trained for this purpose. The radiances were ingested into the NWP using the Ensemble Kalman Filter (EnKF) technique. The horizontal localization has been taken care of, by using a Gaussian localization function centered around the observed coordinates. Similarly, the vertical localization is accomplished by assuming a function which depends on the weighting function of the channel to be assimilated. The effect of both horizontal and vertical localizations has been studied in terms of ensemble spread in the precipitation. Aditionally, improvements in 24 hr forecast from assimilation are also reported.

  16. RADIANCE: An automated, enterprise-wide solution for archiving and reporting CT radiation dose estimates.

    PubMed

    Cook, Tessa S; Zimmerman, Stefan L; Steingall, Scott R; Maidment, Andrew D A; Kim, Woojin; Boonn, William W

    2011-01-01

    There is growing interest in the ability to monitor, track, and report exposure to radiation from medical imaging. Historically, however, dose information has been stored on an image-based dose sheet, an arrangement that precludes widespread indexing. Although scanner manufacturers are beginning to include dose-related parameters in the Digital Imaging and Communications in Medicine (DICOM) headers of imaging studies, there remains a vast repository of retrospective computed tomographic (CT) data with image-based dose sheets. Consequently, it is difficult for imaging centers to monitor their dose estimates or participate in the American College of Radiology (ACR) Dose Index Registry. An automated extraction software pipeline known as Radiation Dose Intelligent Analytics for CT Examinations (RADIANCE) has been designed that quickly and accurately parses CT dose sheets to extract and archive dose-related parameters. Optical character recognition of information in the dose sheet leads to creation of a text file, which along with the DICOM study header is parsed to extract dose-related data. The data are then stored in a relational database that can be queried for dose monitoring and report creation. RADIANCE allows efficient dose analysis of CT examinations and more effective education of technologists, radiologists, and referring physicians regarding patient exposure to radiation at CT. RADIANCE also allows compliance with the ACR's dose reporting guidelines and greater awareness of patient radiation dose, ultimately resulting in improved patient care and treatment. PMID:21969661

  17. Use of MODIS Cloud Top Pressure to Improve Assimilation Yields of AIRS Radiances in GSI

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi

    2014-01-01

    Improvements to global and regional numerical weather prediction have been demonstrated through assimilation of data from NASA's Atmospheric Infrared Sounder (AIRS). Current operational data assimilation systems use AIRS radiances, but impact on regional forecasts has been much smaller than for global forecasts. Previously, it has been shown that cloud top designation associated with quality control procedures within the Gridpoint Statistical Interpolation (GSI) system used operationally by a number of Joint Center for Satellite Data Assimilation (JCSDA) partners may not provide the best representation of cloud top pressure (CTP). Because this designated CTP determines which channels are cloud-free and, thus, available for assimilation, ensuring the most accurate representation of this value is imperative to obtaining the greatest impact from satellite radiances. This paper examines the assimilation of hyperspectral sounder data used in operational numerical weather prediction by comparing analysis increments and numerical forecasts generated using operational techniques with a research technique that swaps CTP from the Moderate-resolution Imaging Spectroradiometer (MODIS) for the value of CTP calculated from the radiances within GSI.

  18. Estimating Expressed Temperature and Fractional Area of Hot Lava at the Kilauea Vent with AVIRIS Spectral Measurements

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    2001-01-01

    Imaging spectroscopy offers a framework based in physics and chemistry for scientific investigation of a wide range of phenomena of interest in the Earth environment. In the scientific discipline of volcanology knowledge of lava temperature and distribution at the surface provides insight into the volcano status and subsurface processes. A remote sensing strategy to measure surface lava temperatures and distribution would support volcanology research. Hot targets such as molten lava emit spectral radiance as a function of temperature. A figure shows a series of Planck functions calculated radiance spectra for hot targets at different temperatures. A maximum Lambertian solar reflected radiance spectrum is shown as well. While similar in form, each hot target spectrum has a unique spectral shape and is distinct from the solar reflected radiance spectrum. Based on this temperature-dependent signature, imaging spectroscopy provides an innovative approach for the remote-sensing-based measurement of lava temperature. A natural site for investigation of the measurement of lava temperature is the Big Island of Hawaii where molten lava from the Kilauea vent is present at the surface. In the past, Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data sets have been used for the analysis of hot volcanic targets and hot burning fires. The research presented here builds upon and extends this earlier work. The year 2000 Hawaii AVIRIS data set has been analyzed to derive lava temperatures taking into account factors of fractional fill, solar reflected radiance, and atmospheric attenuation of the surface emitted radiance. The measurements, analyses, and current results for this research are presented here.

  19. Retrieving Cloud Fraction in the Field-of-View of a High-Spectral Resolution Infrared Radiometer

    SciTech Connect

    Turner, David D.; Holz, R. E.

    2005-07-01

    The combination of radiance from both clear and cloudy regions of sky adds significant uncertainty to retrievals of atmospheric state profiles and cloud microphysical properties from infrared radiometers. In this article, we use observations of radiance from both the 8-13 μm and 3-5 μm bands to retrieve estimates of the cloud fraction in the field-of-view, as well as microphysical cloud The combination of radiance from both clear and cloudy regions of sky adds significant uncertainty to retrievals of atmospheric state profiles and cloud microphysical properties from infrared radiometers. In this article, we use observations of radiance from both the 8-13 μm and 3-5 μm bands to retrieve estimates of the cloud fraction in the field-of-view, as well as microphysical cloud properties, from high-spectral-resolution infrared radiometers. Cloud fraction derived from imagers as well as high-time-resolution observations show good agreement and high correlation with our derived cloud fraction values. This is shown for both ground-based and aircraft based observations. We also demonstrate that the use of the addition information in the 3-5 μm band extends the dynamic range and accuracy of microphysical properties that can be retrieved from infrared radiance data.

  20. A single field of view method for retrieving tropospheric temperature profiles from cloud-contaminated radiance data

    NASA Technical Reports Server (NTRS)

    Hodges, D. B.; Scoggins, J. R.

    1977-01-01

    The paper presents a method for retrieving single field of view tropospheric temperature profiles directly from cloud-contaminated radiance data through the use of auxiliary data such as observed shelter temperatures and estimated cloud-top height. A model was formulated to calculate cloud parameters for use with the radiative transport equation at an estimated cloud-top level. The cloud and temperature data are used in conjunction with real and simulated radiance data from NOAA satellites.

  1. Absolute calibration of a laser system for atmospheric probing.

    PubMed

    Hall, F F; Ageno, H Y

    1970-08-01

    In order to obtain quantitative data on the backscatter function from laser irradiance backscattered from the atmosphere, the ratio of power transmitted to power received must be accurately known. No absolute measurements of power, optical system transmittance, detector quantum efficiency, or electronic gain are necessarily required. The technique of measuring the power ratio by irradiating a smoked or painted target of known diffuse reflectance at a fixed range is used to calibrate a complete lidar system. The relative area of the output power pulse is monitored by a fast response photodiode, and the relative area of the returned pulse is also recorded after passing through a filter of known high optical density. It is essential to control the temperatures of the laser rod and receiver interference prefilter to ensure proper spectral matching. Field experience gained using this technique is described, and examples of calibration measurements and backscatter functions for smog and cirrus clouds are presented.

  2. Absolute photoionization cross sections of the ions Ca+ Ni+

    NASA Astrophysics Data System (ADS)

    Hansen, J. E.; Kjeldsen, H.; Folkmann, F.; Martins, M.; West, J. B.

    2007-01-01

    Absolute measurements of the photoionization cross sections of the singly charged ions in the sequence Ca to Ni are presented, focussing on the 3p → 3d resonance region. Major differences are found in both spectral structure and cross section as the 3d shell is filled progressively. The behaviour of the total oscillator strength is studied as well as its relation to the collapse of the 3d orbital. The 3p53d 1P term is found to have an influence on the spectra even when further 3d electrons are added and this dependence combined with the effect of Hund's rule leads to a considerable simplification in the structure of the absorption spectra before the half-filled 3d shell, while from the half-filled 3d shell Hund's rule is the main simplifying effect.

  3. Absolute Radiation Measurements in Earth and Mars Entry Conditions

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.

    2014-01-01

    This paper reports on the measurement of radiative heating for shock heated flows which simulate conditions for Mars and Earth entries. Radiation measurements are made in NASA Ames' Electric Arc Shock Tube at velocities from 3-15 km/s in mixtures of N2/O2 and CO2/N2/Ar. The technique and limitations of the measurement are summarized in some detail. The absolute measurements will be discussed in regards to spectral features, radiative magnitude and spatiotemporal trends. Via analysis of spectra it is possible to extract properties such as electron density, and rotational, vibrational and electronic temperatures. Relaxation behind the shock is analyzed to determine how these properties relax to equilibrium and are used to validate and refine kinetic models. It is found that, for some conditions, some of these values diverge from non-equilibrium indicating a lack of similarity between the shock tube and free flight conditions. Possible reasons for this are discussed.

  4. Status of MODIS spatial and spectral characterization and performance

    NASA Astrophysics Data System (ADS)

    Link, Dan; Wang, Zhipeng; Xiong, Xiaoxiong

    2016-05-01

    Since launch, both Terra and Aqua MODIS instruments have continued to operate and make measurements of the earth's top of atmospheric (TOA) radiances and reflectance. MODIS collects data in 36 spectral bands covering wavelengths from 0.41 to 14.4 μm. These spectral bands and detectors are located on four focal plane assemblies (FPAs). MODIS on-board calibrators (OBC) include a spectro-radiometric calibration assembly (SRCA), which was designed to characterize and monitor sensor spatial and spectral performance, such as on-orbit changes in the band-to-band registration (BBR), modulation transfer function (MTF), spectral band center wavelengths (CW) and bandwidths (BW). In this paper, we provide a status update of MODIS spatial and spectral characterization and performance, following a brief description of SRCA functions and on-orbit calibration activities. Sensor spatial and spectral performance parameters derived from SRCA measurements are introduced and discussed. Results show that on-orbit spatial performance has been very stable for both Terra and Aqua MODIS instruments. The large BBR shifts in Aqua MODIS, an issue identified pre-launch, have remained the same over its entire mission. On-orbit changes in CW and BW are less than 0.5 nm and 1 nm, respectively, for most VIS/NIR spectral bands of both instruments.

  5. High-radiance LDP source: clean, reliable, and stable EUV source for mask inspection

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    High-throughput and -resolution actinic mask inspection tools are needed as EUVL begins to enter into volume production phase. To realize such inspection tools, a high-radiance EUV source is necessary. Ushio's laser-assisted discharge-produced plasma (LDP) source is able to meet industry's requirements in radiance, cleanliness, stability and reliability. Ushio's LDP source has shown the peak radiance at plasma of 180 W/mm2/sr and the area-averaged radiance in a 200-μm-diameter circle behind the debris mitigation system of 120 W/mm2/sr. A new version of the debris mitigation system is in testing phase. Its optical transmission was confirmed to be 73 %, which is 4 % lower than that of the previous version and therefore will be improved. Cleanliness of the system is evaluated by exposing Ru mirrors placed behind the debris mitigation system. Ru sputter rate was proven to be sufficiently low as 3~5 nm/Gpulse at 7 kHz, whereas frequency-dependent sputter rate was 1~3 nm/Gpulse at 5~9 kHz as previously reported. Sn deposition remained very low (< 0.05 nm) and did not grow over time. A new technique to suppress debris was tested and preliminary results were promising. Time-of-flight signal of fast ions was completely suppressed and Ru sputter rate of exposed mirrors at 3 kHz was approximately 1.3 nm/Gpulse, whereas the conventional mitigation system (new version) resulted in Ru sputter rate of 0.7 nm/Gpulse. This new technique also allows increasing the radiance efficiency by 30 %. Stability tests were done at several different discharge frequencies. Pulse energy stability was approximately 10 %. Dose energy stability dropped from approximately 2 % to 0.1 % when feedback control was activated. EUV emission position stability was studied at 3 kHz. Deviation of the plasma center of gravity was 6 μm, which is 3 % of plasma diameter and therefore considered to be negligible. Reliability tests were performed on both R and D and prototype machines and up to 200 hours of non

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

    PubMed Central

    Dumoulin, Marion; Gaudout, David; Lemaire, Benoit

    2016-01-01

    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 better at the end of the supplementation. Conclusion The oral supplement containing the

  7. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  8. Enabling Dark Energy and Beyond Science with Precise Absolute Photometry

    NASA Astrophysics Data System (ADS)

    Deustua, Susana E.; Hines, D. C.; Bohlin, R.; Gordon, K. D.

    2014-01-01

    We have obtain WFC3/IR observations of 15 carefully selected stars with the immediate objective of establishing their Absolute Physical Flux (ABF), and an ultimate goal of achieving the sub-1% absolute photometric accuracies required by Dark Energy science with JWST and other facilities. Even with the best data available, the current determination of ABFs is plagued by the reliance on the Vega photometric system, which is known to be problematic primarily due to the fact that Vega is a pole-on rapid rotator with an infrared excess from its circumstellar disk! which makes it difficult to model. Vega is also far too bright for large aperture telescopes. In an effort to remedy these difficulties, teams from the National Institute of Standards (NIST), the University of New Mexico, Johns Hopkins University and STScI have begun to develop a catalog of stars that have spectral energy distributions that are tied directly to NIST (diode) standards with very precisely determined physical characteristics. A key element in this pursuit has been the efforts at STScI to measure the spectra of many of these objects with STIS. We discuss our program to extend this effort into the near-IR which is crucial to reliably extend the SEDs to longer wavelengths, including the mid IR.

  9. Using dark current data to estimate AVIRIS noise covariance and improve spectral analyses

    NASA Technical Reports Server (NTRS)

    Boardman, Joseph W.

    1995-01-01

    Starting in 1994, all AVIRIS data distributions include a new product useful for quantification and modeling of the noise in the reported radiance data. The 'postcal' file contains approximately 100 lines of dark current data collected at the end of each data acquisition run. In essence this is a regular spectral-image cube, with 614 samples, 100 lines and 224 channels, collected with a closed shutter. Since there is no incident radiance signal, the recorded DN measure only the DC signal level and the noise in the system. Similar dark current measurements, made at the end of each line are used, with a 100 line moving average, to remove the DC signal offset. Therefore, the pixel-by-pixel fluctuations about the mean of this dark current image provide an excellent model for the additive noise that is present in AVIRIS reported radiance data. The 61,400 dark current spectra can be used to calculate the noise levels in each channel and the noise covariance matrix. Both of these noise parameters should be used to improve spectral processing techniques. Some processing techniques, such as spectral curve fitting, will benefit from a robust estimate of the channel-dependent noise levels. Other techniques, such as automated unmixing and classification, will be improved by the stable and scene-independence noise covariance estimate. Future imaging spectrometry systems should have a similar ability to record dark current data, permitting this noise characterization and modeling.

  10. Exploring a Black Body Source as an Absolute Radiometric Calibration Standard and Comparison with a NIST Traced Lamp Standard

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Chrien, Thomas; Sarture, Chuck

    2001-01-01

    Radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) is required for the scientific research and application objectives pursued with the spectroscopic measurements. Specifically calibration is required for: inter-comparison of AVIRIS data measured at different locations and at different times; analysis of AVIRIS data with data measured by other instruments; and analysis of AVIRIS data in conjunction with computer models. The primary effect of radiometric calibration is conversion of AVIRIS instrument response values (digitized numbers, or DN) to units of absolute radiance. For example, a figure shows the instrument response spectrum measured by AVIRIS over a portion of Rogers Dry Lake, California, and another figure shows the same spectrum calibrated to radiance. Only the calibrated spectrum may be quantitatively analyzed for science research and application objectives. Since the initial development of the AVIRIS instrument-radiometric calibration has been based upon a 1000-W irradiance lamp with a calibration traced to the National Institute of Standards and Technology (NIST). There are several advantages to this irradiance-lamp calibration approach. First, the considerable effort of NIST backs up the calibration. Second, by changing the distance to the lamp, the output can closely span the radiance levels measured by AVIRIS. Third, this type of standard is widely used. Fourth, these calibrated lamps are comparatively inexpensive. Conversely, there are several disadvantages to this approach as well. First, the lamp is not a primary standard. Second, the lamp output characteristics may change in an unknown manner through time. Third, it is difficult to assess, constrain, or improve the calibration uncertainty delivered with the lamp. In an attempt to explore the effect and potentially address some of these disadvantages a set of analyses and measurements comparing an irradiance lamp with a black-body source have been completed

  11. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  12. Benchmarking Climate Model Top-of-atmosphere Radiance in the 9.6 Micron Ozone Band Using TES and IASI Observations

    NASA Astrophysics Data System (ADS)

    Kuai, L.; Worden, H. M.; Bowman, K. W.; Pierre-Francois, C.; Doniki, S.; Neu, J. L.; Kulawik, S. S.; Shindell, D. T.; Conley, A. J.; Lamarque, J. F.; Faluvegi, G.

    2015-12-01

    Biases of present day top-of-atmosphere (TOA) flux for the 9.6 micron ozone band predicted by IPCC chemistry-climate models have never been evaluated with measurements. Ozone band TOA flux biases impact the estimates of ozone radiative forcing (RF) from pre-industrial to present day. Satellite measurements of TOA radiances and ozone profiles allow evaluation of the performance of chemistry-climate models for both TOA flux and Instantaneous Radiative Kernels (IRK), which give the sensitivity of TOA flux to changes in the vertical distribution of atmospheric state, e.g. tropospheric ozone, water or temperature. We compute the ozone band flux and IRK from Aura-TES and MetOP-IASI spectral radiance measurements. The new version of IRKs from TES have been upgraded from the single-angle anisotropy approximation to the more accurate 5-angle Gaussian quadrature integration method and the IRKs are expanded for quantities other than ozone, such as water vapor, temperature, and cloud at this ozone band. These IRKs can be used to attribute changes in ozone band flux to vertical changes in ozone, water vapor and atmospheric temperature, which will help to assess the feedback from vertical changes in the hydrological cycle on the ozone RF. We present comparisons of satellite observed TOA ozone band fluxes and IRKs with RRTMG (Rapid Radiative Transfer Model-GCM applications) in the NCAR CAM-chem chemistry/climate model and with the GISS radiative transfer model. TES observations of ozone and its radiative effect will be used to evaluate the Atmospheric Chemistry Climate Model Intercomparison (ACCMIP) and the Chemistry Climate Model Initiative (CCMI) ensembles in terms of their simulated tropospheric ozone distributions, their effect on TOA flux, and their predictions of future ozone forcing.

  13. Quantum theory allows for absolute maximal contextuality

    NASA Astrophysics Data System (ADS)

    Amaral, Barbara; Cunha, Marcelo Terra; Cabello, Adán

    2015-12-01

    Contextuality is a fundamental feature of quantum theory and a necessary resource for quantum computation and communication. It is therefore important to investigate how large contextuality can be in quantum theory. Linear contextuality witnesses can be expressed as a sum S of n probabilities, and the independence number α and the Tsirelson-like number ϑ of the corresponding exclusivity graph are, respectively, the maximum of S for noncontextual theories and for the theory under consideration. A theory allows for absolute maximal contextuality if it has scenarios in which ϑ /α approaches n . Here we show that quantum theory allows for absolute maximal contextuality despite what is suggested by the examination of the quantum violations of Bell and noncontextuality inequalities considered in the past. Our proof is not constructive and does not single out explicit scenarios. Nevertheless, we identify scenarios in which quantum theory allows for almost-absolute-maximal contextuality.

  14. Absolute calibration in vivo measurement systems

    SciTech Connect

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs.

  15. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record

  16. Quantitative standards for absolute linguistic universals.

    PubMed

    Piantadosi, Steven T; Gibson, Edward

    2014-01-01

    Absolute linguistic universals are often justified by cross-linguistic analysis: If all observed languages exhibit a property, the property is taken to be a likely universal, perhaps specified in the cognitive or linguistic systems of language learners and users. In many cases, these patterns are then taken to motivate linguistic theory. Here, we show that cross-linguistic analysis will very rarely be able to statistically justify absolute, inviolable patterns in language. We formalize two statistical methods--frequentist and Bayesian--and show that in both it is possible to find strict linguistic universals, but that the numbers of independent languages necessary to do so is generally unachievable. This suggests that methods other than typological statistics are necessary to establish absolute properties of human language, and thus that many of the purported universals in linguistics have not received sufficient empirical justification.

  17. Absolute photoacoustic thermometry in deep tissue.

    PubMed

    Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V

    2013-12-15

    Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28°C to 46°C. The temperature measurement accuracy was ~0.6°C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy.

  18. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  19. Absolute Stability And Hyperstability In Hilbert Space

    NASA Technical Reports Server (NTRS)

    Wen, John Ting-Yung

    1989-01-01

    Theorems on stabilities of feedback control systems proved. Paper presents recent developments regarding theorems of absolute stability and hyperstability of feedforward-and-feedback control system. Theorems applied in analysis of nonlinear, adaptive, and robust control. Extended to provide sufficient conditions for stability in system including nonlinear feedback subsystem and linear time-invariant (LTI) feedforward subsystem, state space of which is Hilbert space, and input and output spaces having finite numbers of dimensions. (In case of absolute stability, feedback subsystem memoryless and possibly time varying. For hyperstability, feedback system dynamical system.)

  20. Sounding rocket measurement of the absolute solar EUV flux utilizing a silicon photodiode

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Canfield, L. R.

    1990-01-01

    A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.