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Sample records for absolute solar spectral

  1. 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.

  2. 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°.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. Spectral distribution of solar radiation

    NASA Technical Reports Server (NTRS)

    Mecherikunnel, A. T.; Richmond, J.

    1980-01-01

    Available quantitative data on solar total and spectral irradiance are examined in the context of utilization of solar irradiance for terrestrial applications of solar energy. The extraterrestrial solar total and spectral irradiance values are also reviewed. Computed values of solar spectral irradiance at ground level for different air mass values and various levels of atmospheric pollution or turbidity are presented. Wavelengths are given for computation of solar, absorptance, transmittance and reflectance by the 100 selected-ordinate method and by the 50 selected-ordinate method for air mass 1.5 and 2 solar spectral irradiance for the four levels of atmospheric pollution.

  8. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  9. Solar spectral irradiance model validation using Solar Spectral Irradiance and Solar Radius measurements

    NASA Astrophysics Data System (ADS)

    Thuillier, Gérard; Zhu, Ping; Shapiro, Alexander; Sofia, Sabatino; Tagirov, Rinat; Van Ruymbeke, Michel; Schmutz, Werner

    2016-04-01

    The importance of the reliable solar spectral irradiance (SSI) data for solar and climate physics is now well acknowledged. In particular, the irradiance time series are necessary for most of the current studies concerning climate evolution. However, space instruments are vulnerable to the degradation due to the environment while ground based measurements are limited in wavelength range and need atmospheric effects corrections. This is why SSI modeling is necessary to understand the mechanism of the solar irradiance variability and to provide long and uninterrupted irradiance records to climate and Earth atmosphere scientists. Here we present COSI (COde for Solar Irradiance) model of the SSI variability. The COSI model is based on the Non local thermodynamic Equilibrium Spectral SYnthesis Code (NESSY). We validate NESSY by two independent datasets: - The SSI at solar minimum occurring in 2008, - The radius variation with wavelength and absolute values determined from PREMOS and BOS instruments onboard the PICARD spacecraft. Comparisons between modeling and measured SSI will be shown. However, since SSI measurements have an accuracy estimated between 2 to 3%, the comparison with the solar radius data provides a very important additional constrains on model. For that, 17 partial solar occultations by the Moon are used providing solar radii clearly showing the dependence of the solar radius with wavelength. These results are compared with the NESSY predictions. The agreement between NESSY and observations is within the model and measurements accuracy.

  10. 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%.

  11. Solar Spectral Irradiance and Climate

    NASA Technical Reports Server (NTRS)

    Pilewskie, P.; Woods, T.; Cahalan, R.

    2012-01-01

    Spectrally resolved solar irradiance is recognized as being increasingly important to improving our understanding of the manner in which the Sun influences climate. There is strong empirical evidence linking total solar irradiance to surface temperature trends - even though the Sun has likely made only a small contribution to the last half-century's global temperature anomaly - but the amplitudes cannot be explained by direct solar heating alone. The wavelength and height dependence of solar radiation deposition, for example, ozone absorption in the stratosphere, absorption in the ocean mixed layer, and water vapor absorption in the lower troposphere, contribute to the "top-down" and "bottom-up" mechanisms that have been proposed as possible amplifiers of the solar signal. New observations and models of solar spectral irradiance are needed to study these processes and to quantify their impacts on climate. Some of the most recent observations of solar spectral variability from the mid-ultraviolet to the near-infrared have revealed some unexpected behavior that was not anticipated prior to their measurement, based on an understanding from model reconstructions. The atmospheric response to the observed spectral variability, as quantified in climate model simulations, have revealed similarly surprising and in some cases, conflicting results. This talk will provide an overview on the state of our understanding of the spectrally resolved solar irradiance, its variability over many time scales, potential climate impacts, and finally, a discussion on what is required for improving our understanding of Sun-climate connections, including a look forward to future observations.

  12. The total and spectral solar irradiance and its possible variations

    NASA Technical Reports Server (NTRS)

    Thekaekara, M. P.

    1975-01-01

    The present status of knowledge of the total and spectral irradiance of the sun is briefly reviewed. Currently accepted values of the solar constant and the extraterrestrial solar spectral irradiance are presented along with a discussion of how they were derived. Data on the variability of the solar constant are shown to be conflicting and inconclusive. Some of the alleged sun-weather relationships are cited in support of the need of knowing more precisely the variations in total and spectral solar irradiance. An overview of a solar monitoring program is discussed, with special emphasis on the Solar Energy Monitor in Space experiment which was proposed for several spacecraft missions. It is a combination of a solar constant detector and a prism monochromator. The determination of absolute values and the possible variations of the total and spectral solar irradiance, from measurements outside of the atmosphere is discussed.

  13. 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.

  14. 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).

  15. 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).

  16. 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.

  17. SOHO/CELIAS Solar EUV Monitor (SEM) Absolute Solar EUV Irradiance Measurements Spanning Two Solar Minima (Invited)

    NASA Astrophysics Data System (ADS)

    Wieman, S. R.; Didkovsky, L. V.; Judge, D.

    2010-12-01

    The SOHO/CELIAS Solar EUV Monitor (SEM) has measured absolute EUV solar irradiance nearly continuously over a 15 year period that includes both the cycle 22/23 (1996) and cycle 23/24 (2008) solar minima. These measurements indicate that irradiance in the 26-34 nm spectral range, including the dominant He II 30.4 nm spectral line, was about 15% ± 6% lower during the more recent minimum compared to the previous minimum. The SEM data have been verified against measurements from seven sounding rocket calibration underflights that included a NIST calibrated SEM clone instrument as well as a Rare Gas Ionization Cell (RGIC) absolute extreme ultraviolet (EUV) detector. Additionally, the SEM measurements are in good agreement with measurements from the EUV Spectrophotomer (ESP) part of the EUV Variability Experiment (EVE) on SDO. ESP measurements from the EVE sounding rocket flight (2008) confirmed the very low solar EUV irradiance observed during the 23/24 minimum. A comparison of SEM and ESP data in the 30.4 nm spectral windows is presented.

  18. 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.

  19. Characterization of the DARA solar absolute radiometer

    NASA Astrophysics Data System (ADS)

    Finsterle, W.; Suter, M.; Fehlmann, A.; Kopp, G.

    2011-12-01

    The Davos Absolute Radiometer (DARA) prototype is an Electrical Substitution Radiometer (ESR) which has been developed as a successor of the PMO6 type on future space missions and ground based TSI measurements. The DARA implements an improved thermal design of the cavity detector and heat sink assembly to minimize air-vacuum differences and to maximize thermal symmetry of measuring and compensating cavity. The DARA also employs an inverted viewing geometry to reduce internal stray light. We will report on the characterization and calibration experiments which were carried out at PMOD/WRC and LASP (TRF).

  20. Spectral solar radiation data base documentation

    SciTech Connect

    Riordan, C.J.; Myers, D.R.; Hulstrom, R.L.

    1990-01-01

    The Solar Energy Research Institute (SERI), Electric Power Research Institute, Florida Solar Energy Center, and Pacific Gas and Electric Company cooperated to produce a spectral solar radiation data base representing a range of atmospheric conditions. These data will help to characterize the neutral variability in the spectral (color) content to outdoor solar radiation so that the sensitivity of spectrally selective solar devices (such as photovoltaics) to these variations can be studied quantitatively. Volume 1 of this report documents the history, approach, content, and format of the data base; Volume 2 contains graphs and field notes for each of the spectral data sets. The data reside on magnetic tape at SERI.

  1. MEASUREMENTS OF ABSOLUTE ABUNDANCES IN SOLAR FLARES

    SciTech Connect

    Warren, Harry P.

    2014-05-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory. EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (f). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is f = 1.17 ± 0.22. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation occurs.

  2. Determination of extraterrestrial solar spectral irradiance from a research aircraft.

    PubMed

    Arvesen, J C; Griffin, R N; Pearson, B D

    1969-11-01

    Results are presented of an experiment to determine extraterrestrial solar spectral irradiance at the earth's mean solar distance within the 300-2500 nm wavelength region. Spectroradiometric measurements were performed during eleven research flights on board a NASA CV-990 aircraft at altitudes between 11.6 km and 12.5 km. Precision of the measurements was better than +/-1%. Absolute accuracy of the resultant extraterrestrial solar spectral irradiance is approximately +/-3% over most of the measurement range. A listing of results is presented at intervals varying from 0.1 nm throughout most of the uv-visible Fraunhofer region to 5 nm in the continuum region of the ir. Additionally, a listing of solar spectral irradiance, smoothed over the detailed Fraunhofer structure, is presented for engineering use.

  3. Absolute measurement of the extreme UV solar flux

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Ogawa, H. S.; Judge, D. L.; Phillips, E.

    1984-01-01

    A windowless rare-gas ionization chamber has been developed to measure the absolute value of the solar extreme UV flux in the 50-575-A region. Successful results were obtained on a solar-pointing sounding rocket. The ionization chamber, operated in total absorption, is an inherently stable absolute detector of ionizing UV radiation and was designed to be independent of effects from secondary ionization and gas effusion. The net error of the measurement is + or - 7.3 percent, which is primarily due to residual outgassing in the instrument, other errors such as multiple ionization, photoelectron collection, and extrapolation to the zero atmospheric optical depth being small in comparison. For the day of the flight, Aug. 10, 1982, the solar irradiance (50-575 A), normalized to unit solar distance, was found to be 5.71 + or - 0.42 x 10 to the 10th photons per sq cm sec.

  4. The Measurement of the Solar Spectral Irradiance Variability during the Solar Cycle 24 using SOLAR/SOLSPEC on ISS

    NASA Astrophysics Data System (ADS)

    Bolsée, David; Pereira, Nuno; Pandey, Praveen; Cessateur, Gaël; Gillotay, Didier; Foujols, Thomas; Hauchecorne, Alain; Bekki, Slimane; Marchand, Marion; Damé, Luc; Meftah, Mustapha; Bureau, Jerôme

    2016-04-01

    Since April 2008, SOLAR/SOLSPEC measures the Solar Spectral Irradiance (SSI) from 166 nm to 3088 nm. The instrument is a part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station. As the SSI is a key input for the validation of solar physics models, together with playing a role in the climate system and photochemistry of the Earth atmosphere, SOLAR/SOLSPEC spectral measurements becomes important. In this study, the in-flight operations and performances of the instrument -including the engineering corrections- will be presented for seven years of the SOLAR mission. Following an accurate absolute calibration, the SSI variability in the UV as measured by SOLAR/SOLSPEC in the course of the solar cycle 24 will be presented and compared to other instruments. The accuracy of these measurements will be also discussed here.

  5. 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.

  6. 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.

  7. Absolute Radiometer for Reproducing the Solar Irradiance Unit

    NASA Astrophysics Data System (ADS)

    Sapritskii, V. I.; Pavlovich, M. N.

    1989-01-01

    A high-precision absolute radiometer with a thermally stabilized cavity as receiving element has been designed for use in solar irradiance measurements. The State Special Standard of the Solar Irradiance Unit has been built on the basis of the developed absolute radiometer. The Standard also includes the sun tracking system and the system for automatic thermal stabilization and information processing, comprising a built-in microcalculator which calculates the irradiance according to the input program. During metrological certification of the Standard, main error sources have been analysed and the non-excluded systematic and accidental errors of the irradiance-unit realization have been determined. The total error of the Standard does not exceed 0.3%. Beginning in 1984 the Standard has been taking part in a comparison with the Å 212 pyrheliometer and other Soviet and foreign standards. In 1986 it took part in the international comparison of absolute radiometers and standard pyrheliometers of socialist countries. The results of the comparisons proved the high metrological quality of this Standard based on an absolute radiometer.

  8. 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.

  9. 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

  10. Rotational Variability in Ultraviolet Solar Spectral Irradiance

    NASA Astrophysics Data System (ADS)

    Snow, M. A.; Richard, E. C.; Harder, J. W.; Thuillier, G. O.

    2011-12-01

    There are currently many observations and models of the Solar Spectral Irradiance (SSI) in the ultraviolet (UV). The models and the observations are often in agreement, but sometimes have significant differences. Using the decline of solar cycle 23 and the rise of solar cycle 24 as a test case, we will investigate the systematic differences between the short term SSI variation observed by satellite instruments and the predictions of proxy models.

  11. Solar Spectral Irradiance Changes During Cycle 24

    NASA Technical Reports Server (NTRS)

    Marchenko, Sergey; Deland, Matthew

    2014-01-01

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by approximately 0.6% +/- 0.2% around 265 nm. These changes gradually diminish to 0.15% +/- 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar "continuum." Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar "continuum," the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at lambda approximately or greater than 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  12. Solar spectral irradiance changes during cycle 24

    SciTech Connect

    Marchenko, S. V.; DeLand, M. T.

    2014-07-10

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by ∼0.6% ± 0.2% around 265 nm. These changes gradually diminish to 0.15% ± 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar 'continuum'. Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar 'continuum', the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at λ ≳ 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  13. Spectral Solar Radiation Data Base at NREL

    DOE Data Explorer

    The Solar Energy Research Institute (SERI)*, Electric Power Research Institute (EPRI), Florida Solar Energy Center (FSEC), and Pacific Gas and Electric Company (PG&E) cooperated to produce a spectral solar radiation data base representing a range of atmospheric conditions (or climates) that is applicable to several different types of solar collectors. Data that are included in the data base were collected at FSEC from October 1986 to April 1988, and at PG&E from April 1987 to April 1988. FSEC operated one EPRI and one SERI spectroradiometer almost daily at Cape Canaveral, which contributed nearly 2800 spectra to the data base. PG&E operated one EPRI spectroradiometer at San Ramon, Calif., as resources permitted, contributing nearly 300 spectra to the data base. SERI collected about 200 spectra in the Denver/Golden, Colo., area form November 1987 to February 1988 as part of a research project to study urban spectral solar radiation, and added these data to the data base. *In September 1991 the Solar Energy Research Institute became the National Renewable Energy Laboratory. [Description taken from http://rredc.nrel.gov/solar/old_data/spectral/

  14. Solar spectral measurements and modeling

    SciTech Connect

    Bird, R.E.; Hulstrom, R.L.

    1981-01-01

    A newly developed spectroradiometer for routine measurement of the solar spectra is described. This instrument measures the solar spectrum between 300 and 2500 nm in less than 2.5 min, with 0.7-nm resolution in the visible and 10-nm resolution in the infrared. Many examples of global, direct, and diffuse spectra are illustrated for Bedford, Mass. and Golden, Colo. The effects of air mass, turbidity, and sun tracking on the spectrum are presented, and radiative transfer modeling capabilities and comparisons between models and between models and experiment are discussed.

  15. High spectral resolution in the solar spectrum

    NASA Technical Reports Server (NTRS)

    Baret, F.; Green, R. O.

    1994-01-01

    A session dedicated to high spectral resolution in the solar spectrum, covering topics of calibration, atmospheric correction, geology/pedology, inland water, and vegetation, is reported. The session showed a high degree of diversity in the topics and the approaches used. It was highlighted that high spectral resolution data could provide atmospherically corrected ground level calibrated reflectance values. Important advances were shown in the use of radiative transfer models applied either on water bodies or vegetation. Several studies highlighted the high degree of redundancy contained in high spectral resolution data.

  16. SOLAR/SOLSPEC ultraviolet solar spectral irradiance variability since 2008

    NASA Astrophysics Data System (ADS)

    Damé, Luc; Bolsee, David; Hauchecorne, Alain; Meftah, Mustapha; Bekki, Slimane; Pereira, Nuno

    2016-07-01

    The SOLAR/SOLSPEC experiment measures the Solar Spectral Irradiance (SSI) from the Space Station since April 2008. Measurements are carried between 166 nm and 3088 nm by three double-monochromators. SSI, particularly in the ultraviolet, is a key input to determine the dynamics and coupling of Earth's atmosphere in response to solar and terrestrial inputs. In-flight operations and performances of the instrument, including corrections, will be presented for the 8 years of the mission. After an accurate calibration following recent special on-orbit new operations, we present the variability measured in the UV by SOLAR/SOLSPEC. The accuracy of these measurements will be discussed.

  17. [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.

  18. 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.

  19. Solar abundances with the SPICE spectral imager on Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin, Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany

    2016-07-01

    Elemental composition of the solar atmosphere and in particular abundance bias of low and high First Ionization Potential (FIP) elements are a key tracer of the source regions of the solar wind. These abundances and their spatio-temporal variations, as well as the other plasma parameters , will be derived by the SPICE (Spectral Imaging of the Coronal Environment) EUV spectral imager on the upcoming Solar Orbiter mission. SPICE is designed to provide spectroheliograms (spectral images) using a core set of emission lines arising from ions of both low-FIP and high-FIP elements. These lines are formed over a wide range of temperatures, enabling the analysis of the different layers of the solar atmosphere. SPICE will use these spectroheliograms to produce dynamic composition maps of the solar atmosphere to be compared to in-situ measurements of the solar wind composition of the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to study the connectivity between the spacecraft (the Heliosphere) and the Sun. We will discuss the SPICE capabilities for such composition measurements.

  20. Solar cycle variation in UV solar spectral irradiance

    NASA Astrophysics Data System (ADS)

    Leng Yeo, Kok; Krivova, Natalie; Solanki, Sami K.

    2015-08-01

    Solar spectral irradiance, SSI, in the UV has been measured from space, almost without interruption, since 1978. This is accompanied by the development of models aimed at reconstructing SSI by relating its variability to solar magnetic activity. The various satellite records and model reconstructions differ significantly in terms of the variation over the solar cycle, with the consequence that their application to climate models yield qualitatively different results. Here, we highlight the key discrepancies between available records and reconstructions, and discuss the possible underlying causes.

  1. Normal incidence spectrophotometer using high density transmission grating technology and highly efficiency silicon photodiodes for absolute solar EUV irradiance measurements

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Korde, R.

    1992-01-01

    New developments in transmission grating and photodiode technology now make it possible to realize spectrometers in the extreme ultraviolet (EUV) spectral region (wavelengths less than 1000 A) which are expected to be virtually constant in their diffraction and detector properties. Time dependent effects associated with reflection gratings are eliminated through the use of free standing transmission gratings. These gratings together with recently developed and highly stable EUV photodiodes have been utilized to construct a highly stable normal incidence spectrophotometer to monitor the variability and absolute intensity of the solar 304 A line. Owing to its low weight and compactness, such a spectrometer will be a valuable tool for providing absolute solar irradiance throughout the EUV. This novel instrument will also be useful for cross-calibrating other EUV flight instruments and will be flown on a series of Hitchhiker Shuttle Flights and on SOHO. A preliminary version of this instrument has been fabricated and characterized, and the results are described.

  2. 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.

  3. Long-term measurements of solar spectral irradiance variability: toward the establishment of a climate record

    NASA Astrophysics Data System (ADS)

    Richard, Erik; Harder, Jerald; Pilewskie, Peter; Fontenla, Juan; Woods, Thomas; Brown, Steven; Lykke, Keith

    Knowledge of the top of the atmosphere (TOA) solar spectral irradiance (SSI) is crucial in interpreting the spectrally dependent radiative processes throughout Earth's climate system. Where this energy is deposited into the atmosphere and surface, how the climate responds to solar variability, and the mechanisms of climate response, are highly dependent on how the incident solar radiation is distributed with wavelength. In order to advance understanding of how natural and anthropogenic process affect Earth's climate system there is a strong scientific imperative to maintain accurate, long-term records of climate forcing and response. The contin-uation of SSI measurements provides a unique opportunity to characterize poorly understood wavelength dependent climate processes. Coupled chemistry-climate models require realistic assessments of the magnitudes and long-term trends in SSI for the interpretation and quantifi-cation of solar forcing in climate change scenarios. This places stringent requirements on the absolute calibration of the instrument (tied directly to international standards) and the ability to maintain that calibration on-orbit (long-term stability). The Spectral Irradiance Monitor (SIM) is a solar spectral radiometer that continuously monitors the SSI from 200 nm -2400 nm, a wavelength region encompassing 96% of the total solar irradiance. The SIM instrument is included as part of the Total and Spectral Solar Irradiance Sensor (TSIS) to continue the mea-surement of SSI, which began with the SOlar Radiation and Climate Experiment (SORCE), launched in 2003. SORCE SIM measurements have characterized SSI variability during the descending phase of Solar Cycle (SC) 23, but the determination of multi-solar cycle dependen-cies remains a key climatic uncertainty. Analysis of the measured spectral irradiance variability during the SORCE mission has resulted in a number of instrument design refinements central to maintaining, on-orbit, the long-term absolute

  4. 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%.

  5. 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.

  6. 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

  7. 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.

  8. Solar total and spectral irradiance reconstruction over last 9000 years

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Ju; Usoskin, Ilya; Krivova, Natalie; Solanki, Sami K.

    2016-07-01

    Although the mechanisms of solar influence on Earth climate system are not yet fully understood, solar total and spectral irradiance are considered to be among the main determinants. Solar total irradiance is the total flux of solar radiative energy entering Earth's climate system, whereas the spectral irradiance describes this energy is distributed over the spectrum. Solar irradiance in the UV band is of special importance since it governs chemical processes in the middle and upper atmosphere. On timescales of the 11-year solar cycle and shorter, solar irradiance is measured by space-based instruments while models are needed to reconstruct solar irradiance on longer timescale. The SATIRE-M model (Spectral And Total Irradiance Reconstruction over millennia) is employed in this study to reconstruct solar irradiance from decadal radionuclide isotope data such as 14C and 10Be stored in tree rings and ice cores, respectively. A reconstruction over the last 9000 years will be presented.

  9. 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.

  10. 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% .

  11. 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.

  12. 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.

  13. 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

  14. Observation and Modeling of the Solar Transition Region. 1; Multi-Spectral Solar Telescope Array Observations

    NASA Technical Reports Server (NTRS)

    Oluseyi, Hakeem M.; Walker, A. B. C., II; Porter, Jason; Hoover, Richard B.; Barbee, Troy W., Jr.

    1999-01-01

    We report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.

  15. Future Long-term Measurements of Solar Spectral Irradiance Variability: Achievements and Lessons from the SORCE SIM

    NASA Astrophysics Data System (ADS)

    Richard, E. C.; Harder, J. W.; Pilewskie, P.; Woods, T. N.; Lykke, K.; Brown, S.

    2010-12-01

    In order to advance understanding of how natural and anthropogenic process affect Earth’s climate system there is a strong scientific importance of maintaining accurate, long-term records of climate forcing. The continuation of solar spectral irradiance (SSI) measurements are needed to characterize poorly understood wavelength dependent climate processes. A major challenge quantifying the influence of SSI variability relates directly to the radiometric absolute accuracy and long-term precision of the measurements. The strong reliance on radiative transfer modeling for interpretation and quantification of the deposition of solar radiation in the atmosphere makes it imperative that the spectral distribution of radiant energy entering the atmosphere be known to a high degree of absolute accuracy (tied directly to international standards). The Spectral Irradiance Monitor (SIM) is a solar spectral radiometer that continuously monitors the SSI across the wavelength region spanning the ultraviolet, visible and near infrared (200 nm - 2400 nm, a region encompassing 96% of the total solar irradiance). A future SIM instrument is included as part of the Total and Spectral Solar Irradiance Sensor (TSIS) to continue the measurement of SSI, which began with the SOlar Radiation and Climate Experiment (SORCE), launched in 2003. SORCE SIM measurements have now monitored SSI for a sufficiently long time and over a wide range in solar activity to quantify wavelength-dependent variability form the UV to the near IR. The analysis of the SORCE SIM measurements of solar spectral variability have resulted in a number of instrument design refinements central to maintaining the long-term calibration to SI irradiance standards and achieve the necessary measurement precision and long-term reproducibility (0.05-0.01% per year) to meet the needs for establishing a climate record of solar spectral irradiance into the future.

  16. Spectral light management for solar energy conversion systems

    NASA Astrophysics Data System (ADS)

    Stanley, Cameron; Mojiri, Ahmad; Rosengarten, Gary

    2016-06-01

    Due to the inherent broadband nature of the solar radiation, combined with the narrow spectral sensitivity range of direct solar to electricity devices, there is a massive opportunity to manipulate the solar spectrum to increase the functionality and efficiency of solar energy conversion devices. Spectral splitting or manipulation facilitates the efficient combination of both high-temperature solar thermal systems, which can absorb over the entire solar spectrum to create heat, and photovoltaic cells, which only convert a range of wavelengths to electricity. It has only recently been possible, with the development of nanofabrication techniques, to integrate micro- and nano-photonic structures as spectrum splitters/manipulators into solar energy conversion devices. In this paper, we summarize the recent developments in beam splitting techniques, and highlight some relevant applications including combined PV-thermal collectors and efficient algae production, and suggest paths for future development in this field.

  17. Spectral changes in the zenith skylight during total solar eclipses.

    PubMed

    Hall, W N

    1971-06-01

    The relative spectral intensity of the zenith sky was measured with an optical scanning spectrometer at Nantucket Island, Massachusetts, during the total solar eclipse of 7 March 1970. The spectral ratios I(5100 A)/I(4300 A) and I(5900 A)/I(5100 A) at Nantucket remained unchanged for 96% or less obscuration of the sun by the moon. The results are compared with other recent relative spectral intensity measurements made during total solar eclipses. Comparison with other eclipse measurements for solar elevation angle at totality less than 45 degrees shows a blue color shift consistent with rayleigh scattering. Eclipses with solar elevation angles at totality greater than 45 degrees do not show consistent color shifts. This inconsistency may be due to difficulty in establishing a suitable reference spectrum for comparison with the spectral distribution of the zenith sky at totality. Selection of a suitable reference spectrum is discussed.

  18. Spectral changes in the zenith skylight during total solar eclipses.

    PubMed

    Hall, W N

    1971-06-01

    The relative spectral intensity of the zenith sky was measured with an optical scanning spectrometer at Nantucket Island, Massachusetts, during the total solar eclipse of 7 March 1970. The spectral ratios I(5100 A)/I(4300 A) and I(5900 A)/I(5100 A) at Nantucket remained unchanged for 96% or less obscuration of the sun by the moon. The results are compared with other recent relative spectral intensity measurements made during total solar eclipses. Comparison with other eclipse measurements for solar elevation angle at totality less than 45 degrees shows a blue color shift consistent with rayleigh scattering. Eclipses with solar elevation angles at totality greater than 45 degrees do not show consistent color shifts. This inconsistency may be due to difficulty in establishing a suitable reference spectrum for comparison with the spectral distribution of the zenith sky at totality. Selection of a suitable reference spectrum is discussed. PMID:20111100

  19. Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements

    PubMed Central

    Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Toshimitsu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I–V relations of individual subcells without the need for referencing measured I–V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the “balance sheets” of tandem solar cells. PMID:25592484

  20. A spectral solar/climatic model

    NASA Technical Reports Server (NTRS)

    Sleeper, H. P., Jr.

    1975-01-01

    A summary is presented of pertinent research on solar activity variations and climate variations, together with the presentation of an empirical solar/climatic model that attempts to clarify the nature of the relationships.

  1. Analysis of Solar Spectral Irradiance Measurements from the SBUV/2-Series and the SSBUV Instruments

    NASA Technical Reports Server (NTRS)

    Cebula, Richard P.; DeLand, Matthew T.; Hilsenrath, Ernest

    1996-01-01

    The purpose of this research is to develop a NOAA-11 SBUV/2 solar spectral irradiance data set which is free from long-term instrument drift, then perform scientific analysis using the data set. During the current period of performance, 29 February 1996 through 31 August 1996, we finalized the NOAA-11 SBUV/2 characterization using internal data. This included updating the instrument's electronic, photomultiplier tube gain, wavelength, diffuser degradation, and goniometric calibrations. We have also completed the SSBUV characterization, 1989-1994, and produced SSBUV irradiances for the first seven SSBUV flights. Both of these steps were needed before the long-term calibration of the NOAA-11 SBUV/2 solar spectral irradiance data set via SSBUV can be undertaken. A second major aspect of this work is to compare solar spectral irradiances from the SBUV/2 instruments and SSBUV with corresponding data from other instruments. In the preceding six months, SSBUV data from the ATLAS-3 (November 1994) mission were compared to coincident SUSIM ATLAS-3 data. The GOME instrument was launched by the European Space Agency in early 1995 and began making solar irradiance measurements in May 1995. Working with GOME scientists, we are using SSBUV data to validate the GOME solar irradiance data. Based in part on those findings, the GOME absolute calibration data were reanalyzed.

  2. The Impact of Different Absolute Solar Irradiance Values on Current Climate Model Simulations

    NASA Technical Reports Server (NTRS)

    Rind, David H.; Lean, Judith L.; Jonas, Jeffrey

    2014-01-01

    Simulations of the preindustrial and doubled CO2 climates are made with the GISS Global Climate Middle Atmosphere Model 3 using two different estimates of the absolute solar irradiance value: a higher value measured by solar radiometers in the 1990s and a lower value measured recently by the Solar Radiation and Climate Experiment. Each of the model simulations is adjusted to achieve global energy balance; without this adjustment the difference in irradiance produces a global temperature change of 0.48C, comparable to the cooling estimated for the Maunder Minimum. The results indicate that by altering cloud cover the model properly compensates for the different absolute solar irradiance values on a global level when simulating both preindustrial and doubled CO2 climates. On a regional level, the preindustrial climate simulations and the patterns of change with doubled CO2 concentrations are again remarkably similar, but there are some differences. Using a higher absolute solar irradiance value and the requisite cloud cover affects the model's depictions of high-latitude surface air temperature, sea level pressure, and stratospheric ozone, as well as tropical precipitation. In the climate change experiments it leads to an underestimation of North Atlantic warming, reduced precipitation in the tropical western Pacific, and smaller total ozone growth at high northern latitudes. Although significant, these differences are typically modest compared with the magnitude of the regional changes expected for doubled greenhouse gas concentrations. Nevertheless, the model simulations demonstrate that achieving the highest possible fidelity when simulating regional climate change requires that climate models use as input the most accurate (lower) solar irradiance value.

  3. Spectral sensitization of nanocrystalline solar cells

    DOEpatents

    Spitler, Mark T.; Ehret, Anne; Stuhl, Louis S.

    2002-01-01

    This invention relates to dye sensitized polycrystalline photoelectrochemical solar cells for use in energy transduction from light to electricity. It concerns the utility of highly absorbing organic chromophores as sensitizers in such cells and the degree to which they may be utilized alone and in combination to produce an efficient photoelectrochemical cell, e.g., a regenerative solar cell.

  4. Deployment dynamics of a simplified spinning IKAROS solar sail via absolute coordinate based method

    NASA Astrophysics Data System (ADS)

    Zhao, Jiang; Tian, Qiang; Hu, Hai-Yan

    2013-02-01

    The spinning solar sail of large scale has been well developed in recent years. Such a solar sail can be considered as a rigid-flexible multibody system mainly composed of a spinning central rigid hub, a number of flexible thin tethers, sail membranes, and tip masses. A simplified interplanetary kite-craft accelerated by radiation of the Sun (IKAROS) model is established in this study by using the absolute-coordinate-based (ACB) method that combines the natural coordinate formulation (NCF) describing the central rigid hub and the absolute nodal coordinate formulation (ANCF) describing flexible parts. The initial configuration of the system in the second-stage deployment is determined through both dynamic and static analyses. The huge set of stiff equations of system dynamics is solved by using the generalized-alpha method, and thus the deployment dynamics of the system can be well understood.

  5. High solar cycle spectral variations inconsistent with stratospheric ozone observations

    NASA Astrophysics Data System (ADS)

    Ball, W. T.; Haigh, J. D.; Rozanov, E. V.; Kuchar, A.; Sukhodolov, T.; Tummon, F.; Shapiro, A. V.; Schmutz, W.

    2016-03-01

    Solar variability can influence surface climate, for example by affecting the mid-to-high-latitude surface pressure gradient associated with the North Atlantic Oscillation. One key mechanism behind such an influence is the absorption of solar ultraviolet (UV) radiation by ozone in the tropical stratosphere, a process that modifies temperature and wind patterns and hence wave propagation and atmospheric circulation. The amplitude of UV variability is uncertain, yet it directly affects the magnitude of the climate response: observations from the SOlar Radiation and Climate Experiment (SORCE) satellite show broadband changes up to three times larger than previous measurements. Here we present estimates of the stratospheric ozone variability during the solar cycle. Specifically, we estimate the photolytic response of stratospheric ozone to changes in spectral solar irradiance by calculating the difference between a reference chemistry-climate model simulation of ozone variability driven only by transport (with no changes in solar irradiance) and observations of ozone concentrations. Subtracting the reference from simulations with time-varying irradiance, we can evaluate different data sets of measured and modelled spectral irradiance. We find that at altitudes above pressure levels of 5 hPa, the ozone response to solar variability simulated using the SORCE spectral solar irradiance data are inconsistent with the observations.

  6. Terrestrial solar spectral distributions derived from broadband hourly solar radiation data

    NASA Astrophysics Data System (ADS)

    Myers, Daryl R.

    2009-08-01

    Multiple junction and thin film photovoltaic (PV) technologies respond differently to varying terrestrial spectral distributions of solar energy. PV device and system designers are concerned with the impact of spectral variation on PV specific technologies. Spectral distribution data is generally very rare, expensive, and difficult to obtain. We modified an existing empirical spectral conversion model to convert hourly broadband global (total hemispherical) horizontal and direct normal solar radiation to representative spectral distributions. Hourly average total hemispherical and direct normal beam solar radiation, such as provided in typical meteorological year (TMY) data are model spectral model input data. Default or prescribed atmospheric aerosols and water vapor are possible inputs. Individual hourly and monthly and annual average spectral distributions are computed for a specified tilted surface. The spectral range is from 300 nm to 1400 nm. The model is a modified version of the Nann and Riordan SEDES2 model. Measured hemispherical spectral distributions for a wide variety of conditions at the Solar Radiation Research Laboratory at the National Renewable Energy Laboratory, Golden, Co. and Florida Solar Energy Center (Cocoa, FL) show that reasonable spectral accuracy of about +/-20% is obtainable, with notable exceptions for weather events such as snow.

  7. Spectral estimates of solar radiation intercepted by corn canopies

    NASA Technical Reports Server (NTRS)

    Bauer, M. E. (Principal Investigator); Daughtry, C. S. T.; Gallo, K. P.

    1982-01-01

    Reflectance factor data were acquired with a Landsat band radiometer throughout two growing seasons for corn (Zea mays L.) canopies differing in planting dates, populations, and soil types. Agronomic data collected included leaf area index (LAI), biomass, development stage, and final grain yields. The spectral variable, greenness, was associated with 78 percent of the variation in LAI over all treatments. Single observations of LAI or greenness have limited value in predicting corn yields. The proportions of solar radiation intercepted (SRI) by these canopies were estimated using either measured LAI or greenness. Both SRI estimates, when accumulated over the growing season, accounted for approximately 65 percent of the variation in yields. Models which simulated the daily effects of weather and intercepted solar radiation on growth had the highest correlations to grain yields. This concept of estimating intercepted solar radiation using spectral data represents a viable approach for merging spectral and meteorological data for crop yield models.

  8. Spectral analysis of natural solar ultraviolet B to promote synthesis of vitamin D

    NASA Astrophysics Data System (ADS)

    Hung, Min-Wei; Lin, Yu-Hsuan; Chang, Han-Chao; Huang, Kuo-Cheng

    2016-10-01

    This paper presents a spectral analysis system for the measurement of solar ultraviolet B over long durations. The proposed system provides high resolution at low cost in a highly robust and flexible format. We obtained information pertaining to the absolute irradiance of sunlight in a fixed location with the aim of identifying the best period in which to seek exposure to the sun with regard to maximizing the synthesis of vitamin D while minimizing damage to the skin. This study also provides a means of establishing a database for the development of healthy lamp technology.

  9. Spectral analysis of natural solar ultraviolet B to promote synthesis of vitamin D

    NASA Astrophysics Data System (ADS)

    Hung, Min-Wei; Lin, Yu-Hsuan; Chang, Han-Chao; Huang, Kuo-Cheng

    2016-06-01

    This paper presents a spectral analysis system for the measurement of solar ultraviolet B over long durations. The proposed system provides high resolution at low cost in a highly robust and flexible format. We obtained information pertaining to the absolute irradiance of sunlight in a fixed location with the aim of identifying the best period in which to seek exposure to the sun with regard to maximizing the synthesis of vitamin D while minimizing damage to the skin. This study also provides a means of establishing a database for the development of healthy lamp technology.

  10. Modelling rotational and cyclical spectral solar irradiance variations

    NASA Astrophysics Data System (ADS)

    Unruh, Yvonne

    Solar irradiance changes are highly wavelength dependent: solar-cycle variations in the UV can be on the order of tens of percent, while changes in the visible are typically only of the order of one or two permille. With the launch of a number of instruments to measure spectral solar irradiance, we are now for a first time in a good position to explore the changing solar irradiance over a large range of wavelengths and to test our irradiance models as well as some of their underlying assumptions. I will introduce some of the current modelling approaches and present model-data comparisons, using the SATIRE irradiance model and SORCE/SIM measurements as an example. I will conclude by highlighting a number of outstanding questions regarding the modelling of spectral irradiance and current approaches to address these.

  11. Solar Spectral Irradiance Observations from the PICARD/PREMOS Radiometer

    NASA Astrophysics Data System (ADS)

    Cessateur, G.; Schöll, M.; Schmutz, W. K.; Wehrli, C.; Groebner, J.; Haberreiter, M.; Kretzschmar, M.; Shapiro, A.; Thuillier, G. O.; Finsterle, W.; Fox, N.; Hochedez, J. F.; Koller, S.; Meftah, M.; Nyeki, S.; Pfiffner, D.; Roth, H.; Rouze, M.; Spescha, M.; Tagirov, R.; Werner, L.; Wyss, J.

    2015-12-01

    Space weather and space climate studies require accurate Solar Spectral Irradiance (SSI) observations. The PREcision Monitoring Sensor (PREMOS) instrument aboard the PICARD satellite acquired solar irradiance measurements in specific spectral windows in the UV, visible and near infrared from October 2010 to March 2014. This contribution aims at presenting the Level 3 data, corrected for non solar features as well as for degradation. These level 3 data has been tested over different scientific cases, such as observations during the Venus transit and the presence of the p-mode signature within high-cadence data. The PREMOS Level 3 data have also been compared to others data sets, namely the SOLSTICE and SIM instruments aboard SORCE, for nearly 3 and half years. An excellent correlation has been found for the UV spectral ranges. We have also found a rather good correlation for visible and near-infrared observations for short-term variations, for which an error of about 200 ppm has been estimated within PREMOS visible and near-infrared observations. The PREMOS data could also be used to address several scientific topics, i.e. for validating semi-empirical models of the solar irradiance. We will emphasize about our new irradiance model, COSIR for Code of Solar Irradiance Reconstruction, which is successful at reproducing the solar modulation as seen in the PREMOS, SoHO/Virgo and SORCE data.

  12. Solar Confocal Interferometers for Sub-Picometer-Resolution Spectral Filters

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Pietraszewski, Chris; West, Edward A.; Dines, Terence C.

    2006-01-01

    The confocal Fabry-Perot interferometer allows sub-picometer spectral resolution of Fraunhofer line profiles. Such high spectral resolution is needed to keep pace with the higher spatial resolution of the new set of large-aperture solar telescopes. The line-of-sight spatial resolution derived for line profile inversions would then track the improvements of the transverse spatial scale provided by the larger apertures. The confocal interferometer's unique properties allow a simultaneous increase in both etendue and spectral power. Methods: We have constructed and tested two confocal interferometers. Conclusions: In this paper we compare the confocal interferometer with other spectral imaging filters, provide initial design parameters, show construction details for two designs, and report on the laboratory test results for these interferometers, and propose a multiple etalon system for future testing of these units and to obtain sub-picometer spectral resolution information on the photosphere in both the visible and near-infrared.

  13. Photographic films for the Multi-Spectral Solar Telescope Array

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest, Craig E.; Allen, Maxwell J.; Lindblom, Joakim F.; Gilliam, Lou; November, Larry; Brown, Todd; Dewan, Clyde A.

    1992-01-01

    The rocketborne Multi-Spectral Solar Telescope Array (MSSTA) uses an array of Ritchey-Chretien, Cassegrain, and Herschelian telescopes to produce ultrahigh-resolution full-disk images of the sun within the soft X-ray, EUV, and FUV ranges. Such imaging of the solar disk and corona out to several solar radii placed great demands on the MSSTA's data storage capabilities; in addition, its photographic films required very low outgassing rates. Results are presented from calibration tests conducted on the MSSTA's emulsions, based on measurements at NIST's synchrotron facility.

  14. Lanthanide ions as spectral converters for solar cells.

    PubMed

    van der Ende, Bryan M; Aarts, Linda; Meijerink, Andries

    2009-12-21

    The use of lanthanide ions to convert photons to different, more useful, wavelengths is well-known from a wide range of applications (e.g. fluorescent tubes, lasers, white light LEDs). Recently, a new potential application has emerged: the use of lanthanide ions for spectral conversion in solar cells. The main energy loss in the conversion of solar energy to electricity is related to the so-called spectral mismatch: low energy photons are not absorbed by a solar cell while high energy photons are not used efficiently. To reduce the spectral mismatch losses both upconversion and downconversion are viable options. In the case of upconversion two low energy infrared photons that cannot be absorbed by the solar cell, are added up to give one high energy photon that can be absorbed. In the case of downconversion one high energy photon is split into two lower energy photons that can both be absorbed by the solar cell. The rich and unique energy level structure arising from the 4f(n) inner shell configuration of the trivalent lanthanide ions gives a variety of options for efficient up- and downconversion. In this perspective an overview will be given of recent work on photon management for solar cells. Three topics can be distinguished: (1) modelling of the potential impact of spectral conversion on the efficiency of solar cells; (2) research on up- and downconversion materials based on lanthanides; and (3) proof-of-principle experiments. Finally, an outlook will be given, including issues that need to be resolved before wide scale application of up- and downconversion materials can be anticipated.

  15. Spectral Calibration of the MSFC Solar Ultraviolet Magnetograph

    NASA Technical Reports Server (NTRS)

    West, Edward; Kobayashi, Ken; Cirtain, Jonathan; Gary, Allen; Davis, John; Reader, Joseph

    2009-01-01

    This paper describes the scientific goals of a sounding rocket program called the Solar Ultraviolet Magnetograph Investigation (SUMI), presents a brief description of the optics that were developed to meet those goals and discusses the spectral, spatial and polarization characteristics of SUMI's Toroidal Variable-Line-Space (TVLS) gratings; which are critical to SUMI's measurements of the magnetic field in the Sun's transition region.

  16. Solar cycle effects of spectrally varying solar irradiance in a coupled chemistry--climate model

    NASA Astrophysics Data System (ADS)

    Swartz, W. H.; Stolarski, R. S.; Oman, L.; Fleming, E. L.; Jackman, C. H.

    2010-12-01

    Variation of the solar spectral irradiance (SSI) with solar cycle impacts the composition and temperature of the atmosphere. Stratosphere ozone and temperature, for example, respond through both direct solar heating and photolysis. We have implemented an 11-year solar cycle in the Goddard Earth Observing System Chemistry--Climate Model (GEOS CCM). One of the SSI datasets used is a multi-decadal historical reconstruction based on contemporary observations of solar irradiance and historical proxies for solar activity. We examine the atmospheric response to SSI variations through direct solar heating and photolysis individually and also when coupled in the model. Ozone response is dominated by photolysis, whereas both direct heating and photolysis affect stratospheric temperatures approximately equally. We also find that the magnitude of the atmospheric response is sensitive to the spectral characteristics of the SSI dataset used.

  17. The source of multi spectral energy of solar energetic electron

    SciTech Connect

    Herdiwijaya, Dhani

    2015-04-16

    We study the solar energetic electron distribution obtained from ACE and GOES satellites which have different altitudes and electron spectral energy during the year 1997 to 2011. The electron spectral energies were 0.038–0.315 MeV from EPAM instrument onboard ACE satellite and >2 MeV from GOES satellite. We found that the low electron energy has no correlation with high energy. In spite of we have corrected to the altitude differences. It implied that they originated from time dependent events with different sources and physical processes at the solar atmosphere. The sources of multi spectral energetic electron were related to flare and CME phenomena. However, we also found that high energetic electron comes from coronal hole.

  18. Absolute velocity measurements in the solar transition region and corona from observations of ultraviolet emission line profiles

    NASA Astrophysics Data System (ADS)

    Hassler, Donald M.

    An experimental technique to measure absolute velocities of minor ions formed in the solar transition region and corona is presented. A sounding rocket experiment July 27, 1987 obtained high resolution extreme ultraviolet (EUV) spectra along a solar diameter with spatial resolution of 20 x 20 arcseconds. The center-to-limb behavior of four representative lines (Si II 1553, Fe II 1563, CIV 1548, Ne VIII 770) formed at different heights in the solar atmosphere is discussed. Assuming that horizontal motions cancel statistically so that the line-of-sight velocity approaches zero at the limb, we find a net radial downflow of approximately 7.5 +/- 1.0 km/s for C IV, 2.7 +/- 1.5 km/s for Fe II 1563, and upper limits of 0 +/- 1.2 km/s and 0 +/- 4 km/s for Si II and Ne VIII, respectively. The absolute wavelengths of each emission line were determined by direct comparison with wavelengths of known platinum lines generated by an inflight calibration lamp. We then test the assumption of line-of-sight velocity approaching zero at the limb by comparing our wavelengths with recently published laboratory rest wavelengths of the solar emission lines. We find agreement within the published uncertainties of the laboratory wavelengths. The result for Si II indicates that the next radial flow in the chromosphere is near zero, although small scale velocity structures may vary by as much as 4-6 km/sec. The center-to-limb behavior of Fe II 1563 suggests, contrary to previous thinking, that there might be a significant contribution of Fe II emission at higher temperatures characteristic of the lower transition region. Finally, the upper limit on the radial flow velocity for Ne VIII provides a constraint on the radial flow at coronal temperatures. Complicating the accurate measurement of Doppler velocities is the presence of small nonlinearities in the microchannel plates used in UV and EUV detectors which introduce small position offsets between the input and output of the detector. The

  19. High angular resolution absolute intensity of the solar continuum from 1400 to 1790 A.

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.; Moe, O. K.

    1972-01-01

    Absolute intensities of the solar UV continuum from 1400 to 1790 A have been measured from rocket spectra taken on August 13, 1970. The spectra had an angular resolution of 2 arc sec by 1 arc min, and the pointing accuracy of the instrument was plus or minus 2 arc sec. This permits us to study the center-to-limb variation of the intensity with a spatial resolution of 2 arc sec. Four positions on the solar disk have been studied corresponding to values of cos theta = 0.12, 0.22, 0.28 and 0.72, where theta is the heliocentric position angle. The measurements give higher values for the intensity than recent photoelectric measurement, but are in good agreement with the intensities of Widing et al.

  20. Spectral and spatial properties of solar microflares

    NASA Technical Reports Server (NTRS)

    Simnett, G. M.; Dennis, B. R.

    1985-01-01

    Solar microflares are studied using both hard ( 28 keV) and soft (3.5 to 8.0 keV) X-ray observations. The soft X-ray events have durations 3 m at 0.1x maximum intensity, and typically have similar rise and decay times. The fastest decay observed was 15 s (1/e). Soft and hard X-ray intensities are uncorrelated. The events are very compact, consistent with a projected area approximately 8 x 8 inches. They are normally not associated with H alpha or type 3 emissions and their time profiles suggest a thermal origin at the top of the chromosphere. If the primary energy release site is in the corona, an energy transfer agent consistent with the observations is a non-thermal proton beam.

  1. 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

  2. Solar Confocal interferometers for Sub-Picometer-Resolution Spectral Filters

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Pietraszewski, Chris; West, Edward A.; Dines. Terence C.

    2007-01-01

    The confocal Fabry-Perot interferometer allows sub-picometer spectral resolution of Fraunhofer line profiles. Such high spectral resolution is needed to keep pace with the higher spatial resolution of the new set of large-aperture solar telescopes. The line-of-sight spatial resolution derived for line profile inversions would then track the improvements of the transverse spatial scale provided by the larger apertures. In particular, profile inversion allows improved velocity and magnetic field gradients to be determined independent of multiple line analysis using different energy levels and ions. The confocal interferometer's unique properties allow a simultaneous increase in both etendue and spectral power. The higher throughput for the interferometer provides significant decrease in the aperture, which is important in spaceflight considerations. We have constructed and tested two confocal interferometers. A slow-response thermal-controlled interferometer provides a stable system for laboratory investigation, while a piezoelectric interferometer provides a rapid response for solar observations. In this paper we provide design parameters, show construction details, and report on the laboratory test for these interferometers. The field of view versus aperture for confocal interferometers is compared with other types of spectral imaging filters. We propose a multiple etalon system for observing with these units using existing planar interferometers as pre-filters. The radiometry for these tests established that high spectral resolution profiles can be obtained with imaging confocal interferometers. These sub-picometer spectral data of the photosphere in both the visible and near-infrared can provide important height variation information. However, at the diffraction-limited spatial resolution of the telescope, the spectral data is photon starved due to the decreased spectral passband.

  3. Astronomy and solar physics: measurement of the solar spectral irradiance from 200 to 3000 nanometers.

    PubMed

    Thuillier, G; Goutail, J P; Simon, P C; Pastiels, R; Labs, D; Neckel, H

    1984-07-13

    The solar spectrum experiment on Spacelab 1 measured 98 percent of the sun's total energy output. It improved the absolute accuracy of solar irradiance data, especially in the ultraviolet and infrared regions. In order to detect any variation in the spectrum on future shuttle flights, the data were obtained in a radiation scale that can be preserved with high precision over many years. The instrument performance and preliminary data reduction are described.

  4. Spectral solar irradiance before and during a Harmattan dust spell

    SciTech Connect

    Adeyefa, Z.D.; Holmgren, B.

    1996-09-01

    Measurements of the ground-level spectral distributions of the direct, diffuse and global solar irradiance between 300 and 1100 nm were made at Akure (7.15{degree}N, 5.5{degree}E), Nigeria, in December 1991 before and during a Harmattan dust spell employing a spectroradiometer (LICOR LI-1800) with 6 nm resolution. The direct spectral solar irradiance which was initially reduced before the dust storm was further attenuated by about 50% after the spell. Estimated values of the Angstrom turbidity coefficient {beta} indicated an increase of about 146% of this parameter while the Angstrom wavelength-exponent {alpha} decreased by about 65% within the 2-day study period. The spectral diffuse-to-direct and diffuse-to-global ratios suggest that the main cause of the significant reduction in solar irradiance at the surface was the scattering by the aerosol which led to an increase in the diffuse component. The global irradiance though reduced, was less sensitive to changing Harmattan conditions. It is recommended that solar energy devices that use radiation from Sun and sky be used under fluctuating Harmattan conditions. There are some deviations from the Angstrom formula under very turbid Harmattan conditions which could be explained by the relative increase of the particle sizes. 31 refs., 12 figs., 3 tabs.

  5. Total and Spectral Solar Irradiance Sensor (TSIS) Project Overview

    NASA Technical Reports Server (NTRS)

    Carlisle, Candace; Wedge, Ronnice; Wu, Dong; Stello, Harry; Robinson, Renee

    2015-01-01

    The main objective of the Total and Spectral solar Irradiance Sensor (TSIS) is to acquire measurements to determine the direct and indirect effects of solar radiation on climate. TSIS total solar irradiance measurements will extend a 37-year long uninterrupted measurement record of incoming solar radiation, the dominant energy source driving the Earths climate and the most precise indicator of changes in the Suns energy output. TSIS solar spectral irradiance measurements will determine the regions of the Earths multi-layered atmosphere that are affected by solar variability, from which the solar forcing mechanisms causing changes in climate can be quantified. TSIS includes two instruments: the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), integrated into a single payload. The TSIS TIM and SIM instruments are upgraded versions of the two instruments that are flying on the Solar Radiation and Climate Experiment (SORCE) mission launched in January 2003. TSIS was originally planned for the nadir-pointing National Polar-orbiting Operational Environmental Satellite System (NPOESS) spacecraft. The TSIS instrument passed a Critical Design Review (CDR) for NPOESS in December 2009. In 2010, TSIS was re-planned for the Joint Polar Satellite System (JPSS) Polar Free Flyer (PFF). The TSIS TIM, SIM, and associated electronics were built, tested, and successfully completed pre-ship review as of December 2013.In early 2014, NOAA and NASA agreed to fly TSIS on the International Space Station (ISS). In the FY16 Presidents Budget, NASA assumes responsibility for the TSIS mission on ISS. The TSIS project includes requirements, interface, design, build and test of the TSIS payload, including an updated pointing system, for accommodation on the ISS. It takes advantage of the prior development of the TSIS sensors and electronics. The International Space Station (ISS) program contributions include launch services and robotic installation of the TSIS payload

  6. Modeling the spectral solar irradiance in the SOTERIA Project Framework

    NASA Astrophysics Data System (ADS)

    Vieira, Luis Eduardo; Dudok de Wit, Thierry; Kretzschmar, Matthieu; Cessateur, Gaël

    The evolution of the radiative energy input is a key element to understand the variability of the Earth's neutral and ionized atmospheric components. However, reliable observations are limited to the last decades, when observations realized above the Earth's atmosphere became possible. These observations have provide insights about the variability of the spectral solar irradiance on time scales from days to years, but there is still large uncertainties on the evolu-tion on time scales from decades to centuries. Here we discuss the physics-based modeling of the ultraviolet solar irradiance under development in the Solar-Terrestrial Investigations and Archives (SOTERIA) project framework. In addition, we compare the modeled solar emission with variability observed by LYRA instrument onboard of Proba2 spacecraft.

  7. Solar EUV Monitor (SEM) absolute irradiance measurements and how they are affected by choice of reference spectrum

    NASA Astrophysics Data System (ADS)

    Wieman, Seth R.; Judge, Darrell L.; Didkovsky, Leonid V.

    2011-10-01

    The SOHO/CELIAS Solar EUV Monitor (SEM) has measured absolute extreme ultraviolet (EUV) solar irradiance nearly continuously over a 15 year period that includes two solar cycle minima, 22/23 (1996) and 23/24 (2008). Calibration of the SEM flight instrument and verification of the data have been maintained through measurements from a series of sounding rocket calibration underflights that have included a NIST calibrated SEM clone instrument as well as a Rare Gas Ionization Cell (RGIC) absolute detector. From the beginning of SEM data collection in 1996, the SOLERS 22 fixed reference solar spectrum has been used to calculate absolute EUV flux values from SEM raw data. Specifically, the reference spectrum provides a set of weighting factors for determining a weighted average for the wavelength dependent SEM response. The spectrum is used for calculation of the second order contamination in the first order channel signals, and for the comparison between SEM flux measurements with broader-band absolute RGIC measurements. SOHO/SEM EUV flux measurements for different levels of solar activity will be presented to show how the choice of reference spectra now available affects these SEM data. Both fixed (i.e. SOLERS 22) and non-fixed (Solar Irradiance Platform/Solar 2000 and SDO/EVE/MEGS) reference spectra have been included in this analysis.

  8. The correction for spectral mismatch effects on the calibration of a solar cell when using a solar simulator

    NASA Technical Reports Server (NTRS)

    Seaman, C. H.

    1981-01-01

    A general expression was derived to enable calculation of the calibration error. The information required includes the relative spectral response of the reference cell, the relative spectral response of the cell under test, and the relative spectral irradiance of the simulator (over the spectral range defined by cell response). The spectral irradiance of the solar AMX is assumed to be known.

  9. Solar UV Spectral Irradiance Measured by SUSIM During Solar Cycle 22 and 23

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; Floyd, L. E.; McMullin, D. R.

    2011-12-01

    Understanding the impact of solar variability on terrestrial climate requires detailed knowledge of both solar spectral irradiance (SSI) and total solar irradiance (TSI). Observations of SSI in the ultraviolet (UV) have been made by various space-based missions since 1978. Of these missions, the Upper Atmosphere Research Satellite (UARS) included the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) experiment which measured the UV SSI from 1991 into 2005. In this talk, we present the UV spectral irradiance observations from SUSIM on UARS during solar cycles 22 and 23 along with results of a recent review of the calibration, stability, and in-flight performance. Another more recent mission is the Solar Radiation and Climate Experiment (SORCE) satellite which carries the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) and Solar Irradiance Monitor (SIM). Together, the SORCE instruments have measured the UV, Visible, and IR SSI over the period of 2003 to the present. This talk will include a comparison between SUSIM and SORCE during the period of overlapping observations as well as comparisons of UV spectra observed at various times, particularly during the last two solar minima. These comparisons show that the UV observations by SORCE are inconsistent with those measured by SUSIM.

  10. SOLAR RADIO BURSTS WITH SPECTRAL FINE STRUCTURES IN PREFLARES

    SciTech Connect

    Zhang, Yin; Tan, Baolin; Huang, Jing; Tan, Chengming; Karlický, Marian; Mészárosová, Hana; Simões, Paulo J.A.

    2015-01-20

    Good observations of preflare activities are important for us to understand the origin and triggering mechanism of solar flares, and to predict the occurrence of solar flares. This work presents the characteristics of microwave spectral fine structures as preflare activities of four solar flares observed by the Ondřejov radio spectrograph in the frequency range of 0.8-2.0 GHz. We found that these microwave bursts which occurred 1-4 minutes before the onset of flares have spectral fine structures with relatively weak intensities and very short timescales. They include microwave quasi-periodic pulsations with very short periods of 0.1-0.3 s and dot bursts with millisecond timescales and narrow frequency bandwidths. Accompanying these microwave bursts are filament motions, plasma ejection or loop brightening in the EUV imaging observations, and non-thermal hard X-ray emission enhancements observed by RHESSI. These facts may reveal certain independent, non-thermal energy releasing processes and particle acceleration before the onset of solar flares. They may help us to understand the nature of solar flares and to predict their occurrence.

  11. Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

    NASA Astrophysics Data System (ADS)

    Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

    2016-09-01

    Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

  12. Radiation scales on which standard values of the solar constant and solar spectral irradiance are based

    NASA Technical Reports Server (NTRS)

    Thekaekara, M. P.

    1972-01-01

    The question of radiation scales is critically examined. There are two radiation scales which are of fundamental validity and there are several calibration standards and radiation scales which have been set up for practical convenience. The interrelation between these scales is investigated. It is shown that within the limits of accuracy of irradiance measurements in general and solar irradiance measurements in particular, the proposed standard values of the solar constant and solar spectrum should be considered to be on radiation scales of fundamental validity; those based on absolute electrical units and on the thermodynamic Kelvin temperature scale.

  13. PREMOS Absolute Radiometer Calibration and Implications to on-orbit Measurements of the Total Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Fehlmann, A.; Kopp, G.; Schmutz, W. K.; Winkler, R.; Finsterle, W.; Fox, N.

    2011-12-01

    On orbit measurements starting in the late 1970's, have revealed the 11 year cycle of the Total Solar Irradiance (TSI). However, the absolute results from individual experiments differ although all instrument teams claim to measure an absolute value. Especially the data from the TIM/SORCE experiment confused the community as it measures 0.3 % lower than the other instruments, e.g. VIRGO/SOHO by PMOD/WRC, which clearly exceeds the uncertainty stated for the absolute characterization of the experiments. The PREMOS package on the PICARD platform launched in June 2010 is the latest space experiment by PMOD/WRC measuring the TSI. We have put great effort in the calibration and characterization of this instrument in order to resolve the inter-instrument differences. We performed calibrations at the National Physical Laboratory (NPL) in London and the Laboratory for Atmospheric and Space Physics (LASP) in Boulder against national SI standards for radiant power using a laser beam with a diameter being smaller than the aperture of the instrument. These measurements together with the World Radiometric Reference (WRR) calibration in Davos allowed to compare the WRR and the SI radiant power scale. We found that the WRR lies 0.18 % above the SI radiant power scale which explains a part of the VIRGO-TIM difference. The Total solar irradiance Radiometer Facility (TRF) at the LASP allows to generate a beam that over fills the apertures of our instruments, giving the presently best available representation of solar irradiance in a laboratory. These irradiance calibrations revealed a stray light contribution between 0.09 and 0.3 % to the measurements which had been underestimated in the characterization of our instruments. Using the irradiance calibrations, we found that the WRR lies 0.32 % above the TRF scale which in turn explains the full VIRGO-TIM difference. The first light PREMOS measurements in space confirmed our findings. If we use the WRR calibration, PREMOS yields a TSI

  14. A rare gas optics-free absolute photon flux and energy analyzer for solar and planetary observations

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    We have developed a prototype spectrometer for space applications requiring long term absolute EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  15. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    NASA Astrophysics Data System (ADS)

    Stolarski, R. S.; Swartz, W. H.; Jackman, C. H.; Fleming, E. L.

    2011-12-01

    Recent measurements from the SIM instrument on the SORCE satellite have been interpreted by Harder et al (Geophys. Res. Lett., 36, L07801, doi:10.1029/2008GL036797, 2009) as implying a different spectral irradiance variation over the solar cycle than that put forward by Lean (Geophys. Res. Lett., 27, 2425-2428, 2000). When we inserted this new wavelength dependent solar cycle variation into our 3D CCM we found a different solar cycle dependence of the ozone concentration as a function of altitude from that we derived using the traditional Lean wavelength dependence. Examination of these results led us to realize that the main issue is the solar cycle variation of radiation at wavelengths less than 240 nm versus the solar cycle variation of radiation at wavelengths between 240 nm and 300 nm. The impact of wavelengths less than 240 nm occurs through photodissociation of O2 leading to the production of ozone. The impact of wavelengths between 240 nm and 300 nm occurs through photodissociation of O3 leading to an increase in O atoms and enhanced ozone destruction. Thus one wavelength region gives an in-phase relationship of ozone with the solar cycle while the other wavelength region gives an out-of-phase relationship of ozone with the solar cycle. We have used the Goddard two-dimensional (2D) photochemistry transport model to examine this relationship in more detail. We calculate the altitude and latitude sensitivity of ozone to changes in the solar UV irradiance as a function of wavelength. These results can be used to construct the ozone response to arbitrary wavelength dependencies of solar UV variation.

  16. SBUV/2 Long-Term Measurements of Solar Spectral Variability

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Cebula, Richard P.

    1997-01-01

    The NOAA-11 SBUV/2 spectral solar data have been corrected for long-term instrument changes to produce a 5.5 year data record during solar cycle 22 (December 1988 - October 1994). Residual drifts in the data at long wavelengths are +/- 1% or less. At 200-205 nm, where solar variations drive stratospheric photochemistry, these data indicate long-term solar changes of 5-7% from the maximum of Cycle 22 in April 1991 through the end of the NOAA-11 data record. Comparisons of NOAA-11 data with UARS SUSIM and SOLSTICE for the period October 1991 - October 1994, when all 3 instruments were operating simultaneously, show that the observed long-term variations in 200-205 nm irradiance agree to within 2%. This result is consistent with predictions from the Mg-2 proxy index. The SBUV/2 instruments represent a valuable resource for long-term solar UV activity studies because of their overlapping data records. In addition to the NOAA-11 data presented here, the NOAA-9 SBUV/2 instrument began taking data in March 1985 and is still operating, providing a complete record of Cycle 22 behavior from a single instrument. Three additional SBUV/2 instruments are scheduled to be launched between 1997 and 2003, which should permit full coverage of solar cycle 23.

  17. Solar-Reflectance-Based Calibration of Spectral Radiometers

    NASA Technical Reports Server (NTRS)

    Cattrall, Christopher; Carder, Kendall L.; Thome, Kurtis J.; Gordon, Howard R.

    2001-01-01

    A method by which to calibrate a spectral radiometer using the sun as the illumination source is discussed. Solar-based calibrations eliminate several uncertainties associated with applying a lamp-based calibration to field measurements. The procedure requires only a calibrated reflectance panel, relatively low aerosol optical depth, and measurements of atmospheric transmittance. Further, a solar-reflectance-based calibration (SRBC), by eliminating the need for extraterrestrial irradiance spectra, reduces calibration uncertainty to approximately 2.2% across the solar-reflective spectrum, significantly reducing uncertainty in measurements used to deduce the optical properties of a system illuminated by the sun (e.g., sky radiance). The procedure is very suitable for on-site calibration of long-term field instruments, thereby reducing the logistics and costs associated with transporting a radiometer to a calibration facility.

  18. Uncertainty of measurements of spectral solar UV irradiance

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Seckmeyer, G.

    Most investigations on the nature and effects of solar ultraviolet (UV) radiation at the Earth's surface require measurements of high accuracy combined with well-defined procedures to assess their quality. Here we present a general evaluation of all relevant errors and uncertainties associated with measurements of spectral global irradiance in the UV. The uncertainties are quantified in terms of dependence of the characteristics of the spectroradiometer, the uncertainty of calibration standards, the solar zenith angle, and atmospheric conditions. The methodologies and equations presented can be applied to most spectroradiometers currently employed for UV research. The sources of error addressed include radiometric calibration, cosine error, spectral resolution, wavelength misalignment, stability, noise, stray light, and timing errors. The practical application of the method is demonstrated by setting up a complete uncertainty table for the mobile spectroradiometer of the Fraunhofer Institute for Atmospheric Environmental Research (IFU). This instrument has successfully participated in several international intercomparisons of UV spectroradiometers. The expanded uncertainty (coverage factor k=2) for measurements of global spectral irradiance conducted with this instrument varies between 6.3% in the UVA and 12.7% at 300 nm and 60° solar zenith angle. The expanded uncertainties in erythemally and DNA weighted irradiances are 6.1% and 6.6%, respectively. These expanded uncertainties are comparable to uncertainties at the 2σ level in conventional statistics. A substantial reduction of these uncertainties would require smaller uncertainties in the irradiance standards used to calibrate the instrument. Though uncertainties caused by wavelength misalignment and noise become prominent in the shortwave UVB, which is the most important spectral range for UV trend detection, the results indicate that the accuracy of the IFU radiometer is sufficient to detect long-term trends

  19. 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.

  20. High spectral resolution imager for solar induced fluorescence observation

    NASA Astrophysics Data System (ADS)

    Barducci, A.; Guzzi, D.; Lastri, C.; Marcoionni, P.; Nardino, V.; Pippi, I.; Raimondi, V.; Sandri, P.

    2011-11-01

    The use of high-resolution imagers for determination of solar-induced fluorescence of natural bodies by observing the infilling of Fraunhofer lines has been frequently adopted as a tool for vegetation characterization. The option to perform those measurements from airborne platforms was addressed in the past. In-field observations gave evidence of the main requirements for an imaging spectrometer to be used for Sun-induced fluorescence measurements such as high spectral resolution and fine radiometric accuracy needed to resolve the shape of observed Fraunhofer lines with a high level of accuracy. In this paper, some solutions for the design of a high spectral resolution push-broom imaging spectrometer for Sun-induced fluorescence measurements are analysed. The main constraints for the optical design are a spectral resolution better than 0.01 nm and a wide field of view. Due to the fine instrumental spectral resolution, bidimensional focal plane arrays characterized by high quantum efficiency, low read-out noise, and high sensitivity are requested. The development of a lightweight instrument is a benefit for aerospace implementations of this technology. First results coming from laboratory measurements and optical simulations are presented and discussed taking into account their feasibility.

  1. A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Bell, Cameron P. M.; Mamajek, Eric E.; Naylor, Tim

    2015-11-01

    We present a self-consistent, absolute isochronal age scale for young ( ≲ 200 Myr), nearby ( ≲ 100 pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-empirical pre-main-sequence model isochrones using the τ2 maximum-likelihood fitting statistic of Naylor & Jeffries in the MV, V - J colour-magnitude diagram. The final adopted ages for the groups are as follows: 149^{+51}_{-19} {Myr} for the AB Dor moving group, 24 ± 3 Myr for the β Pic moving group (BPMG), 45^{+11}_{-7} {Myr} for the Carina association, 42^{+6}_{-4} {Myr} for the Columba association, 11 ± 3 Myr for the η Cha cluster, 45 ± 4 Myr for the Tucana-Horologium moving group (Tuc-Hor), 10 ± 3 Myr for the TW Hya association and 22^{+4}_{-3} {Myr} for the 32 Ori group. At this stage we are uncomfortable assigning a final, unambiguous age to the Argus association as our membership list for the association appears to suffer from a high level of contamination, and therefore it remains unclear whether these stars represent a single population of coeval stars. Our isochronal ages for both the BPMG and Tuc-Hor are consistent with recent lithium depletion boundary (LDB) ages, which unlike isochronal ages, are relatively insensitive to the choice of low-mass evolutionary models. This consistency between the isochronal and LDB ages instils confidence that our self-consistent, absolute age scale for young, nearby moving groups is robust, and hence we suggest that these ages be adopted for future studies of these groups. Software implementing the methods described in this study is available from http://www.astro.ex.ac.uk/people/timn/tau-squared/.

  2. Solar spectral irradiance and summary outputs using excel.

    PubMed

    Diffey, Brian

    2015-01-01

    The development of an Excel spreadsheet is described that calculates solar spectral irradiance between 290-3000 nm on an unshaded, horizontal surface under a cloudless sky at sea level, together with summary outputs such as global UV index, illuminance and percentage of energy in different wavebands. A deliberate goal of the project was to adopt the principle of Ockham's razor and to develop a model that is as simple as it can be commensurate with delivering results of adequate accuracy. Consequently, just four inputs are required-geographical latitude, month, day of month and time of day-resulting in a spreadsheet that is easily usable by anyone with an interest in sunlight and solar power irrespective of their background. The accuracy of the calculated data is sufficient for many applications where knowledge of the ultraviolet, visible and infrared levels in sunlight is of interest. PMID:25644778

  3. Solar spectral irradiance and summary outputs using excel.

    PubMed

    Diffey, Brian

    2015-01-01

    The development of an Excel spreadsheet is described that calculates solar spectral irradiance between 290-3000 nm on an unshaded, horizontal surface under a cloudless sky at sea level, together with summary outputs such as global UV index, illuminance and percentage of energy in different wavebands. A deliberate goal of the project was to adopt the principle of Ockham's razor and to develop a model that is as simple as it can be commensurate with delivering results of adequate accuracy. Consequently, just four inputs are required-geographical latitude, month, day of month and time of day-resulting in a spreadsheet that is easily usable by anyone with an interest in sunlight and solar power irrespective of their background. The accuracy of the calculated data is sufficient for many applications where knowledge of the ultraviolet, visible and infrared levels in sunlight is of interest.

  4. Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms

    NASA Astrophysics Data System (ADS)

    Dasi-Espuig, M.; Jiang, J.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Yeo, K. L.

    2016-05-01

    Aims: We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a surface flux transport model fed with semi-synthetic records of emerging sunspot groups. Methods: The record of sunspot group areas and positions from the Royal Greenwich Observatory (RGO) is only available since 1874. We used statistical relationships between the properties of sunspot group emergence, such as the latitude, area, and tilt angle, and the sunspot cycle strength and phase to produce semi-synthetic sunspot group records starting in the year 1700. The semi-synthetic records are fed into a surface flux transport model to obtain daily simulated magnetograms that map the distribution of the magnetic flux in active regions (sunspots and faculae) and their decay products on the solar surface. The magnetic flux emerging in ephemeral regions is accounted for separately based on the concept of extended cycles whose length and amplitude are linked to those of the sunspot cycles through the sunspot number. The magnetic flux in each surface component (sunspots, faculae and network, and ephemeral regions) was used to compute the spectral and total solar irradiance (TSI) between the years 1700 and 2009. This reconstruction is aimed at timescales of months or longer although the model returns daily values. Results: We found that SATIRE-T2, besides reproducing other relevant observations such as the total magnetic flux, reconstructs the TSI on timescales of months or longer in good agreement with the PMOD composite of observations, as well as with the reconstruction starting in 1878 based on the RGO-SOON data. The model predicts an increase in the TSI of 1.2+0.2-0.3 Wm-2 between 1700 and the present. The spectral irradiance reconstruction is in good agreement with the UARS/SUSIM measurements as well as the Lyman-α composite. The

  5. The Multi-Spectral Solar Telescope Array (MSSTA)

    NASA Technical Reports Server (NTRS)

    Walker, A. B. C., Jr.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1997-01-01

    In 1987, our consortium pioneered the application of normal incidence multilayer X-ray optics to solar physics by obtaining the first high resolution narrow band, "thermally differentiated" images of the corona', using the emissions of the Fe IX/Fe X complex at ((lambda)lambda) approx. 171 A to 175 A, and He II Lyman (beta) at 256 A. Subsequently, we developed a rocket borne solar observatory, the Multi Spectral Solar Telescope Array (MSSTA) that pioneered multi-thermal imaging of the solar atmosphere, using high resolution narrow band X-ray, EUV and FUV optical systems. Analysis of MSSTA observations has resulted in four significant insights into the structure of the solar atmosphere: (1) the diameter of coronal loops is essentially constant along their length; (2) models of the thermal and density structure of polar plumes based on MSSTA observations have been shown to be consistent with the thesis that they are the source of high speed solar wind streams; (3) the magnetic structure of the footpoints of polar plumes is monopolar, and their thermal structure is consistent with the thesis that the chromosphere at their footpoints is heated by conduction from above; (4) coronal bright points are small loops, typically 3,500 - 20,000 km long (5 sec - 30 sec); their footpoints are located at the poles of bipolar magnetic structures that are are distinguished from other network elements by having a brighter Lyman a signature. Loop models derived for 26 bright points are consistent with the thesis that the chromosphere at their footpoints is heated by conduction from the corona.

  6. 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.

  7. The Solar Spectral Irradiance as a Function of the Mg II Index for Atmosphere and Climate Modelling

    NASA Technical Reports Server (NTRS)

    Thuillier, Gerard; DeLand, Matthew; Shapiro, Alexander; Schmutz, Werner; Bolsee, David; Melo, Stella

    2011-01-01

    In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar

  8. 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

  9. Fine structure of the age-chromospheric activity relation in solar-type stars. I. The Ca II infrared triplet: Absolute flux calibration

    NASA Astrophysics Data System (ADS)

    Lorenzo-Oliveira, D.; Porto de Mello, G. F.; Dutra-Ferreira, L.; Ribas, I.

    2016-10-01

    Context. Strong spectral lines are useful indicators of stellar chromospheric activity. They are physically linked to the convection efficiency, differential rotation, and angular momentum evolution and are a potential indicator of age. However, for ages > 2 Gyr, the age-activity relationship remains poorly constrained thus hampering its full application. Aims: The Ca II infrared triplet (IRT lines, λλ 8498, 8542, and 8662) has been poorly studied compared to classical chromospheric indicators. We report in this paper absolute chromospheric fluxes in the three Ca II IRT lines, based on a new calibration tied to up-to-date model atmospheres. Methods: We obtain the Ca II IRT absolute fluxes for 113 FGK stars from high signal-to-noise ratio (S/N) and high-resolution spectra covering an extensive domain of chromospheric activity levels. We perform an absolute continuum flux calibration for the Ca II IRT lines anchored in atmospheric models calculated as an explicit function of effective temperatures (Teff), metallicity ([Fe/H]), and gravities (log g) avoiding the degeneracy usually present in photometric continuum calibrations based solely on color indices. Results: The internal uncertainties achieved for continuum absolute flux calculations are ≈2% of the solar chromospheric flux, one order of magnitude lower than for photometric calibrations. Using Monte Carlo simulations, we gauge the impact of observational errors on the final chromospheric fluxes due to the absolute continuum flux calibration and find that Teffuncertainties are properly mitigated by the photospheric correction leaving [Fe/H] as the dominating factor in the chromospheric flux uncertainty. Conclusions: Across the FGK spectral types, the Ca II IRT lines are sensitive to chromospheric activity. The reduced internal uncertainties reported here enable us to build a new chromospheric absolute flux scale and explore the age-activity relation from the active regime down to very low activity levels and

  10. 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.

  11. Solar Irradiance from 165 to 400 nm in 2008 and UV Variations in Three Spectral Bands During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Bolsée, D.; Damé, L.; Hauchecorne, A.; Pereira, N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thiéblemont, R.

    2016-10-01

    Accurate measurements of the solar spectral irradiance (SSI) and its temporal variations are of primary interest to better understand solar mechanisms, and the links between solar variability and Earth's atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to carry out SSI measurements from 165 to 3088 nm. We focus here on the ultraviolet (UV) part of the measured solar spectrum (wavelengths less than 400 nm) because the UV part is potentially important for understanding the solar forcing of Earth's atmosphere and climate. We present here SOLAR/SOLSPEC UV data obtained since 2008, and their variations in three spectral bands during Solar Cycle 24. They are compared with previously reported UV measurements and model reconstructions, and differences are discussed.

  12. Enhancement of Spectral Response of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Chang, Shuai

    Dye-Sensitized solar cell (DSSC) is a class of third-generation solar devices. A notable feature of DSSC is that it can be manufactured by solution-based approach; this non-vacuum processing renders significant reduction in manufacturing costs. Different from conventional solar cells, in a DSSC, mesoporous semiconductor film with large surface areas is utilized for anchoring dye molecules, serving as light absorbing layer. Dye sensitizers play an important role in determining the final performance in DSSCs. Since the first highly-efficient DSSC was reported in 1991 sensitized by a ruthenium-based dye, numerous researchers have been focused on the development and characterization of various kinds of dyes for the applications in DSSCs. These include mainly metal complexes dyes, organic dyes, porphyrins and phthalocyanines dyes. The first part of my thesis work is to develop and test new dyes for DSSCs and a series of phenothiazine-based organic dyes and new porphyrin dyes are reported during the process. It has been realized that extending the response of dye sensitizers to a wider range of the solar spectrum is a key step in further improving the device efficiency. Typically, there are two ways for expanding the strong spectral response of DSSCs from visible to far red/NIR region. One approach is called co-sensitization. Herein, we demonstrate a new co-sensitization concept where small molecules is used to insert the interstitial site of between the pre-adsorbed large molecules. In this case, the co-adsorbed small ones is found to improve the light response and impede the back recombination, finally leading to the power conversion efficiency over 10% in conventional DSSC devices and a record-equaling efficiency of 9.2% in quasi-solid-state devices. I also implemented graphene sheets in the anode films for better charge transfer efficiency and break the energy conversion limit of co-sensitization in DSSCs. The optimal configuration between porphyrin dyes and

  13. Solar Spectral Irradiance Variations in 240 - 1600 nm During the Recent Solar Cycles 21 - 23

    NASA Astrophysics Data System (ADS)

    Pagaran, J.; Weber, M.; Deland, M. T.; Floyd, L. E.; Burrows, J. P.

    2011-08-01

    Regular solar spectral irradiance (SSI) observations from space that simultaneously cover the UV, visible (vis), and the near-IR (NIR) spectral region began with SCIAMACHY aboard ENVISAT in August 2002. Up to now, these direct observations cover less than a decade. In order for these SSI measurements to be useful in assessing the role of the Sun in climate change, records covering more than an eleven-year solar cycle are required. By using our recently developed empirical SCIA proxy model, we reconstruct daily SSI values over several decades by using solar proxies scaled to short-term SCIAMACHY solar irradiance observations to describe decadal irradiance changes. These calculations are compared to existing solar data: the UV data from SUSIM/UARS, from the DeLand & Cebula satellite composite, and the SIP model (S2K+VUV2002); and UV-vis-IR data from the NRLSSI and SATIRE models, and SIM/SORCE measurements. The mean SSI of the latter models show good agreement (less than 5%) in the vis regions over three decades while larger disagreements (10 - 20%) are found in the UV and IR regions. Between minima and maxima of Solar Cycles 21, 22, and 23, the inferred SSI variability from the SCIA proxy is intermediate between SATIRE and NRLSSI in the UV. While the DeLand & Cebula composite provide the highest variability between solar minimum and maximum, the SIP/Solar2000 and NRLSSI models show minimum variability, which may be due to the use of a single proxy in the modeling of the irradiances. In the vis-IR spectral region, the SCIA proxy model reports lower values in the changes from solar maximum to minimum, which may be attributed to overestimations of the sunspot proxy used in modeling the SCIAMACHY irradiances. The fairly short timeseries of SIM/SORCE shows a steeper decreasing (increasing) trend in the UV (vis) than the other data during the descending phase of Solar Cycle 23. Though considered to be only provisional, the opposite trend seen in the visible SIM data

  14. A STATISTICAL STUDY OF SPECTRAL HARDENING IN SOLAR FLARES AND RELATED SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Grayson, James A.; Krucker, Saem; Lin, R. P. E-mail: krucker@ssl.berkeley.ed

    2009-12-20

    Using hard X-ray observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we investigate the reliability of spectral hardening during solar flares as an indicator of related solar energetic particle (SEP) events at Earth. All RHESSI data are analyzed, from 2002 February through the end of Solar Cycle 23, thereby expanding upon recent work on a smaller sample of flares. Previous investigations have found very high success when associating soft-hard-harder (SHH) spectral behavior with energetic proton events, and confirmation of this link would suggest a correlation between electron acceleration in solar flares and SEPs seen in interplanetary space. In agreement with these past findings, we find that of 37 magnetically well-connected flares (W30-W90), 12 of 18 flares with SHH behavior produced SEP events and none of 19 flares without SHH behavior produced SEPs. This demonstrates a statistically significant dependence of SHH and SEP observations, a link that is unexplained in the standard scenario of SEP acceleration at the shock front of coronal mass ejections and encourages further investigation of the mechanisms which could be responsible.

  15. The Effects of Water Vapor and Clouds on the Spectral Distribution of Solar Radiation at the...

    NASA Technical Reports Server (NTRS)

    Pilewskie, P.; Bergstrom, R.; Mariani, P.; Gore, Warren J. Y. (Technical Monitor)

    1997-01-01

    During the Subsonic Contrail and Cloud Effect Special Study (SUCCESS) a Solar Spectral Flux Radiometer was deployed at the surface in a zenith observing position. The instrument measured the solar spectral downwelling irradiance between 350 and 2500 nm with 10 nm resolution. From April 12 through April 29 approximately 18000 spectra were acquired, under a variety of meteorological conditions including cloud free, cirrus, Stearns, and cumulonimbus clouds. This study focuses on the effect of cirrus and cirrus contrails on the spectral distribution of solar irradiance at the surface and on inferring cirrus properties from their spectral transmittance. The observations have also proven to be useful for comparing the solar spectral irradiance measurements with model predictions, and in particular, for inferring the amount of solar radiation absorbed in the clear and cloudy atmosphere.

  16. Solar Spectral Irradiance, Solar Activity, and the Near-Ultra-Violet

    NASA Astrophysics Data System (ADS)

    Fontenla, J. M.; Stancil, P. C.; Landi, E.

    2015-08-01

    The previous calculations of the Solar Spectral Irradiance (SSI) by the Solar Radiation Physical Modeling, version 2 system, are updated in this work by including new molecular photodissociation cross-sections of important species, and many more levels and lines in its treatment of non-LTE radiative transfer. The current calculations including the new molecular photodissociation opacities produce a reduced over-ionizaton of heavy elements in the lower chromosphere and solve the problems with prior studies of the UV SSI in the wavelength range 160-400 nm and now reproduce the available observations with much greater accuracy. Calculations and observations of the near-UV at 0.1 nm resolution and higher are compared. The current set of physical models includes four quiet-Sun and five active-region components, from which radiance is computed for ten observing angles. These radiances are combined with images of the solar disk to obtain the SSI and Total Solar Irradiance and their variations. The computed SSI is compared with measurements from space at several nm resolution and agreement is found within the accuracy level of these measurements. An important result is that the near-UV SSI increase with solar activity is significant for the photodissociation of ozone in the terrestrial atmosphere because a number of highly variable upper chromospheric lines overlap the ozone Hartley band.

  17. The measurement of solar spectral irradiances at wavelengths between 40 and 4000 A

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1983-01-01

    Two 1/8-meter Ebert-Fastie spectrometers were refurbished and upgraded in order to measure the solar spectral irradiances between 1160 A and 3100 A. An evacuated 1/4-meter normal-incidence spectrometer was also fabricated for spectral irradiance measurements over the wavelength range from 1250 A to 250 A. Procedures were developed for the calibration of all three instruments utilizing standards at the National Bureau of Standards. The two 1/8-meter spectrometers were flown to measure the solar spectral irradiances near solar maximum on two different dates. Data from these flights were analyzed. The performance of the spectrometers, and the results of an analysis of the variabilities of the solar spectral irradiances over the solar cycles 20 and 21 are discussed.

  18. Absolute integrated intensity and individual line parameters for the 6.2-micron band of NO2. [in solar spectrum

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Bonomo, F. S.; Williams, W. J.; Murcray, D. G.; Snider, D. E.

    1975-01-01

    The absolute integrated intensity of the 6.2-micron band of NO2 at 40 C was determined from quantitative spectra at about 10 per cm resolution by the spectral band model technique. A value of 1430 plus or minus 300 per sq cm per atm was obtained. Individual line parameters, positions, intensities, and ground-state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at about 0.5 per cm resolution.

  19. Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.

    1976-01-01

    Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

  20. 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.

  1. A new solar irradiance calibration from 3295 A to 8500 A derived from absolute spectrophotometry of Vega

    NASA Technical Reports Server (NTRS)

    Lockwood, G. W.; Tueg, H.; White, N. M.

    1992-01-01

    By imaging sunlight diffracted by 20- and 30-micron diameter pinholes onto the entrance aperture of a photoelectric grating scanner, the solar spectral irradiance was determined relative to the spectrophotometric standard star Vega, observed at night with the same instrument. Solar irradiances are tabulated at 4 A increments from 3295 A to 8500 A. Over most of the visible spectrum, the internal error of measurement is less than 2 percent. This calibration is compared with earlier irradiance measurements by Neckel and Labs (1984) and by Arvesen et al. (1969) and with the high-resolution solar atlas by Kurucz et al. The three calibrations agree well in visible light but differ by as much as 10 percent in the ultraviolet.

  2. Solar Spectral Proxy Irradiance from GOES (SSPRING): a model for solar EUV irradiance

    NASA Astrophysics Data System (ADS)

    Suess, Katherine; Snow, Martin; Viereck, Rodney; Machol, Janet

    2016-02-01

    Several currently operating instruments are able to measure the full EUV spectrum at sufficient wavelength resolution for use in upper-atmosphere modeling, the effects of space weather, and modeling satellite drag. However, no missions are planned at present to succeed the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and Solar Dynamics Observatory (SDO) missions, which currently provide these data sources. To develop a suitable replacement for these measurements, we use two broadband EUV channels on the NOAA GOES satellites, the magnesium core-to-wing ratio (Mg II index) from the SOlar Radiation and Climate Experiment (SORCE) as well as EUV and Mg II time averages to model the EUV spectrum from 0.1 to 105 nm at 5-nm spectral resolution and daily time resolution. A Levenberg-Marquardt least squares fitting algorithm is used to determine a coefficient matrix that best reproduces a reference data set when multiplied by input data. The coefficient matrix is then applied to model data outside of the fitting interval. Three different fitting intervals are tested, with a variable fitting interval utilizing all days of data before the prediction date producing the best results. The correlation between the model results and the observed spectrum is found to be above 95% for the 0.1-50 nm range, and between 74% and 95% for the 50-105 nm range. We also find a favorable comparison between our results and the Flare Irradiance Spectral Model (FISM). These results provide a promising potential source for an empirical EUV spectral model after direct EUV measurements are no longer available, and utilize a similar EUV modeling technique as the upcoming GOES-R satellites.

  3. Solar rotation measurements at Mount Wilson. II - Systematic instrumental effects and the absolute rotation rate

    NASA Technical Reports Server (NTRS)

    Labonte, B. J.; Howard, R.

    1981-01-01

    Possible sources of systematic error in solar Doppler rotational velocities are examined. Scattered light is shown to affect the Mount Wilson solar rotation results, but this effect is not enough to bring the spectroscopic results in coincidence with the sunspot rotation. Interference fringes at the spectrograph focus at Mount Wilson have in two intervals affected the rotation results. It has been possible to correlate this error with temperature and thus correct for it. A misalignment between the entrance and exit slits is a possible source of error, but for the Mount Wilson slit configuration, the amplitude of this effect is negligibly small. Rapid scanning of the solar image also produces no measurable effect.

  4. 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.

  5. Calibration of a Solar Absolute Cavity Radiometer with Traceability to the World Radiometric Reference

    SciTech Connect

    Reda, I.

    1996-01-01

    This report describes the present method of establishing traceability of absolute cavity radiometers to the World Radiometric Reference (WRR) through the process employed in the International Pyrheliometer Comparisons (IPC). This method derives the WRR reduction factor for each of the participating cavity radiometers. An alternative method is proposed, described, and evaluated as a way to reduce the uncertainty in the comparison process. The two methods are compared using a sample of data from the recent IPC-VIII conducted from September 25th to October 13th, 1995 at the World Radiation Center in Davos, Switzerland. A description of absolute cavity radiometers is also included, using a PMO-6 as an example of active cavity radiometers, and a HF as an example of passive cavity radiometers.

  6. Quantifying solar spectral irradiance in aquatic habitats for the assessment of photoenhanced toxicity

    USGS Publications Warehouse

    Barron, M.G.; Little, E.E.; Calfee, R.; Diamond, S.

    2000-01-01

    The spectra and intensity of solar radiation (solar spectral irradiance [SSI]) was quantified in selected aquatic habitats in the vicinity of an oil field on the California coast. Solar spectral irradiance measurements consisted of spectral scans (280-700 rim) and radiometric measurements of ultraviolet (UV): UVB (280-320 nm) and UVA (320-400 nm). Solar spectral irradiance measurements were taken at the surface and at various depths in two marsh ponds, a shallow wetland, an estuary lagoon, and the intertidal area of a high-energy sandy beach. Daily fluctuation in SSI showed a general parabolic relationship with time; maximum structure-activity relationship (SAR) was observed at approximate solar noon. Solar spectral irradiance measurements taken at 10-cm depth at approximate solar noon in multiple aquatic habitats exhibited only a twofold variation in visible light and UVA and a 4.5-fold variation in UVB. Visible light ranged from 11,000 to 19,000 ??W/cm2, UVA ranged from 460 to 1,100 ??W/cm2, and UVB ranged from 8.4 to 38 ??W/cm2. In each habitat, the attenuation of light intensity with increasing water depth was differentially affected over specific wavelengths of SSI. The study results allowed the development of environmentally realistic light regimes necessary for photoenhanced toxicity studies.

  7. Solar Spectral Irradiance at 782 nm as Measured by the SES Sensor Onboard Picard

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki, S.; Damé, L.; Bolsée, D.; Pereira, N.

    2016-04-01

    Picard is a satellite dedicated to the simultaneous measurement of the total and solar spectral irradiance, the solar diameter, the solar shape, and to the Sun's interior through the methods of helioseismology. The satellite was launched on June 15, 2010, and pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the satellite. The SES sensor produced an image of the Sun at 782 ± 2.5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782 nm from 2010 to 2014. During this period of Solar Cycle 24, the amplitude of the changes has been of the order of ± 0.08 %, corresponding to a range of about 2× 10^{-3} W m^{-2} nm^{-1}. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm. SES data show similar amplitude variations with the semi-empirical model Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S), whereas the Spectral Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and Climate Experiment satellite (SORCE) highlights higher amplitudes.

  8. Dynamic Power Spectral Analysis of Solar Measurements from Photospheric, Chromospheric, and Coronal Sources

    NASA Technical Reports Server (NTRS)

    Bouwer, S. D.; Pap, J.; Donnelly, R. F.

    1990-01-01

    An important aspect in the power spectral analysis of solar variability is the quasistationary and quasiperiodic nature of solar periodicities. In other words, the frequency, phase, and amplitude of solar periodicities vary on time scales ranging from active region lifetimes to solar cycle time scales. Here, researchers employ a dynamic, or running, power spectral density analysis to determine many periodicities and their time-varying nature in the projected area of active sunspot groups (S sub act). The Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor (SMM/ACRIM) total solar irradiance (S), the Nimbus-7 MgII center-to-wing ratio (R (MgII sub c/w)), the Ottawa 10.7 cm flux (F sub 10.7), and the GOES background x ray flux (X sub b) for the maximum, descending, and minimum portions of solar cycle 21 (i.e., 1980 to 1986) are used. The technique dramatically illustrates several previously unrecognized periodicities. For example, a relatively stable period at about 51 days has been found in those indices which are related to emerging magnetic fields. The majority of solar periodicities, particularly around 27, 150 and 300 days, are quasiperiodic because they vary in amplitude and frequency throughout the solar cycle. Finally, it is shown that there are clear differences between the power spectral densities of solar measurements from photospheric, chromospheric, and coronal sources.

  9. Reconstruction of total and spectral solar irradiance in the satellite era

    NASA Astrophysics Data System (ADS)

    Kok Leng, Yeo; Krivova, Natalie; Solanki, Sami

    2014-05-01

    Total and spectral solar irradiance are key to understanding the influence of the Sun on changes in the Earth's climate, and also represent a useful index of solar activity from the apparent relationship with solar magnetism. We present a SATIRE-S model reconstruction of total and spectral solar irradiance spanning the period of 1974 to 2013. The model ascribes variation in solar irradiance, on timescales greater than a day, to the occurrence and evolution of magnetic structures on the photosphere. This is an update of preceding efforts with the model based on full disc magnetograms from the KPVT and SoHO/MDI. We extended the model to the present with similar observations from SDO/HMI, and cross calibrated the various magnetogram data sets to yield a single, consistent solar irradiance time series. The decadal trend in the PMOD composite record of total solar irradiance is almost exactly reproduced, giving support to solar surface magnetism as a driver of secular variation in solar irradiance. The reconstruction exhibits excellent agreement with various measurements of spectral solar irradiance (R2 ≠³ 0.9) but diverge significantly from the observations from SORCE/SIM, adding to existing evidence that SIM measurements might contain unresolved instrumental trends.

  10. 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.

  11. 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.

  12. First Steps Towards a Homogeneous Solar Spectral Irradiance Data Set: Selection, merging and quality assessment

    NASA Astrophysics Data System (ADS)

    Scholl, Micha; Kretzschmar, Matthieu; Dudok de Wit, Thierry

    2014-05-01

    The Sun varies over different timescales, from minutes to months, decades and millennia. Its variation is an important driver of terrestrial climate change and as such a significant input to climate models. While several observations exist to date over a broad frequency range, they are sparse over both frequency and time. As part of the SOLID (First European comprehensive SOlar Irradiance Data Exploitation) project we will show first results of constructing a homogeneous solar spectral irradiance data set of the UV. By combining a large variety of solar spectral irradiance data sets, we aim to reconstruct spectral solar variability further back in time and to deliver a data set that can be used by others, e.g. climate researchers in order to account for the non-constant solar forcing. We present the data used, together with preliminary internal uncertainty and error-estimates, self-consistent quality assessments, gap-filling methods and selection criteria. We use a combination of observed solar spectral irradiance from several missions, starting with OSO III in 1967, as well as available proxy data to identify outliers and trace them back to either instrumental or physical cause. The SOLID project is part of the seventh European framework programme. SOLID brings together representatives from all European solar space experiments and European teams specialized in irradiance modelling, reconstruction and solar image processing.

  13. Relative spectral absorption of solar radiation by water vapor and cloud droplets

    NASA Technical Reports Server (NTRS)

    Davies, R.; Ridgway, W. L.

    1983-01-01

    A moderate (20/cm) spectral resolution model which accounts for both the highly variable spectral transmission of solar radiation through water vapor within and above cloud, as well as the more slowly varying features of absorption and anisotropic multiple scattering by the cloud droplets, is presented. Results from this model as applied to the case of a typical 1 km thick stratus cloud in a standard atmosphere, with cloud top altitude of 2 km and overhead sun, are discussed, showing the relative importance of water vapor above the cloud, water vapor within the cloud, and cloud droplets on the spectral absorption of solar radiation.

  14. 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

  15. The Variability of Solar Spectral Irradiance and Solar Surface Indices Through the Solar Activity Cycles 21-23

    NASA Astrophysics Data System (ADS)

    Deniz Goker, Umit

    2016-07-01

    A study of variations of solar spectral irradiance (SSI) in the wavelength ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We developed a special software for extracting the data and reduced this data by using the MATLAB. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) emission lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar cycles (SCs) 23 and 24. We also compared our results with the ground-based telescopes as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal Data (KKL) and NGDC Homepage (Rome and Learmonth Solar Observatories). We studied the variations of total solar irradiance (TSI), magnetic field, sunspots/sunspot groups, Ca II K-flux, faculae and plage areas data with these ground-based telescopes, respectively. We reduced the selected data using the Phyton programming language and plot with the IDL programme. Therefore, we found that there was a decrease in the area of bright faculae and chromospheric plages while the percentage of dark faculae and plage decrease, as well. However, these decreases mainly occurred in small sunspots, contrary to this, these terms in large sunspot groups were comparable to previous SCs or even larger. Nevertheless, negative correlations between ISSN and SSI data indicate that these emissions are in close connection with the classes of sunspots/sunspot groups and "PLAGE" regions. Finally, we applied the time series of the chemical elements correspond to the wavelengths 121.5 nm-300.5 nm and compared with the ISSN data. We found an unexpected increasing in the 298.5 nm for the Fe II element. The variability of Fe II (298.5 nm) is in close connection with the plage regions and the sizes of the

  16. Application of Solar Spectral Irradiance Variability in a Earth Atmospheric Model

    NASA Astrophysics Data System (ADS)

    Harder, J. W.; Merkel, A.; Fontenla, J.; Marsh, D.; Woods, T. N.

    2010-12-01

    The Spectral Irradiance Monitor (SIM) measures solar spectral variability in the 200-2400 nm range, accounting for about 97% of the total solar irradiance (TSI). SIM monitored the descending phase of solar cycle 23 and is now continuing these observations into the rising phase of cycle 24. The SIM observations indicate a slower evolutionary trend in solar spectral irradiance (SSI) over solar cycle times periods that are both in and out of phase with the TSI. To estimate the atmospheric response to the solar variability implied by these observations, quiet sun and active solar reference spectra were created as input into the Whole Atmosphere Community Climate Model (WACCM). The SIM observations were combined with the SORCE SOLSTICE instrument in the 110-240 nm range and SRPM (Solar Radiation Physical Modeling) estimates in the infrared beyond the 2400 nm measurement limit of SIM to generate the reference spectra. The model output suggest a very different response in ozone than from atmospheric forcing from semi-empirical models of SSI. The model predicts a reduction in lower mesosphere at higher solar activity and a large increase in mid- to upper stratosphere. This structure can be explained by enhanced production of HOx,, and O3 self-healing effect. This structure is commensurate with contemporaneous observations of O3 from AURA-MLS and SABER.

  17. The new climate data record of total and spectral solar irradiance: Current progress and future steps

    NASA Astrophysics Data System (ADS)

    Coddington, Odele; Lean, Judith; Rottman, Gary; Pilewskie, Peter; Snow, Martin; Lindholm, Doug

    2016-04-01

    We present a climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. TSI and SSI are constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor (TIM), Spectral Irradiance Monitor (SIM), and SOlar Stellar Irradiance Comparison Experiment (SOLSTICE). We show that TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales and we assume that SSI measurements are reliable on solar rotational time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled TSI and SSI with the measurement record and with other solar irradiance models. We also discuss ongoing work to assess the sensitivity of the modeled irradiances to model assumptions, namely, the scaling of solar variability from rotational-to-cycle time scales and the representation of the sunspot darkening index.

  18. Absolute fluxes, equivalent width and centre-to-limb profiles of the solar MG II resonance lines

    NASA Astrophysics Data System (ADS)

    Greve, A.; McKeith, C. D.

    1980-10-01

    For the average quiet Sun we derive from high resolution Fabry Perot-echelle spectrograms profiles of the Mg II resonance lines in the wavelength region 2760 Å ≲ λ ≲ 2820 Å for the radial positions 1.0 ≧ = μ ≧ 0.995, 0.60±0.06 and 0.43±0.10. The profile of a plage region near the disc centre is also presented. From the absolute flux calibrated observations of Kachalov and Jakovleva (1962), and Tousey et al. (1974), we derive the Mg II flux profile in the wavelength region 2660 Å ≲ λ ≲ 2940 Å. The Minnaert-Houtgast method is applied to the far wings of this profile in order to determine the undisturbed continuum level. Related to this continuum the equivalent width of the Mg II resonance lines is 83 Å. For the region 2770 Å ≲ λ ≲ 2820 Å a wavelength averaged limb darkening curve is derived. The Mg II profiles are calibrated using a combination of this limb darkening curve and the low spectral resolution flux profile. Our profile for the disc centre agrees in shape and absolute intensity with Kohl and Parkinson's (1976) recent observation. In the Appendix we generalize the Minnaert-Houtgast method for a blend of two strong multiplet lines and a linear variation of the continuum intensity.

  19. What Do Millimeter Continuum and Spectral Line Observations Tell Us about Solar System Bodies?

    NASA Technical Reports Server (NTRS)

    Milam, Stefanie N.

    2013-01-01

    Solar system objects are generally cold and radiate at low frequencies and tend to have strong molecular rotational transitions. Millimeter continuum and spectral line observations provide detailed information for nearly all solar system bodies. At these wavelengths, details of the bulk physical composition of icy surfaces, the size and albedo of small objects, the composition of planetary atmospheres can be measured as well as monitoring of time variable phenomena for extended periods (not restricted to nighttime observations), etc. Major issues in solar system science can be addressed by observations in the millimeter/sub-millimeter regime such as the origin of the solar system (isotope ratios, composition) and the evolution of solar system objects (dynamics, atmospheric constituents, etc). ALMA s exceptional sensitivity, large spectral bandwidth, high spectral resolution, and angular resolution (down to 10 milliarcsec) will enable researchers for the first time to better resolve the smallest bodies in the solar system and provide detailed maps of the larger objects. Additionally, measurements with nearly 8 GHz of instantaneous bandwidth to fully characterize solar system object s spectrum and detect trace species. The spatial information and line profiles can be obtained over 800 GHz of bandwidth in 8 receiver bands to not only assist in the identification of spectral lines and emission components for a given species but also to help elucidate the chemistry of the extraterrestrial bodies closest to us.

  20. THE HUBBLE WIDE FIELD CAMERA 3 TEST OF SURFACES IN THE OUTER SOLAR SYSTEM: SPECTRAL VARIATION ON KUIPER BELT OBJECTS

    SciTech Connect

    Fraser, Wesley C.; Brown, Michael E.; Glass, Florian

    2015-05-01

    Here, we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 (WFC3) Test of Surfaces in the Outer Solar System. Twelve targets were re-observed with the WFC3 in the optical and NIR wavebands designed to complement those used during the first visit. Additionally, all of the observations originally presented by Fraser and Brown were reanalyzed through the same updated photometry pipeline. A re-analysis of the optical and NIR color distribution reveals a bifurcated optical color distribution and only two identifiable spectral classes, each of which occupies a broad range of colors and has correlated optical and NIR colors, in agreement with our previous findings. We report the detection of significant spectral variations on five targets which cannot be attributed to photometry errors, cosmic rays, point-spread function or sensitivity variations, or other image artifacts capable of explaining the magnitude of the variation. The spectrally variable objects are found to have a broad range of dynamical classes and absolute magnitudes, exhibit a broad range of apparent magnitude variations, and are found in both compositional classes. The spectrally variable objects with sufficiently accurate colors for spectral classification maintain their membership, belonging to the same class at both epochs. 2005 TV189 exhibits a sufficiently broad difference in color at the two epochs that span the full range of colors of the neutral class. This strongly argues that the neutral class is one single class with a broad range of colors, rather than the combination of multiple overlapping classes.

  1. A New Climate Data Record of Solar Spectral Irradiance from 1610 to Present

    NASA Astrophysics Data System (ADS)

    Coddington, O.; Lean, J.; Pilewskie, P.; Snow, M. A.; Lindholm, D. M.

    2015-12-01

    We present a climate data record of Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. SSI is constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM); the measurements are assumed to be reliable on solar rotational time scales. We extend the SSI record to longer time scales by reproducing the integral of the SSI with independent measurements of Total Solar Irradiance (TSI) measurements made by the SORCE Total Irradiance Monitor (TIM); TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled SSI with the measurement record and with other solar irradiance models. We also discuss future work to improve the Solar Irradiance Climate Data Record with new measurements from the Total and Spectral Solar Irradiance Sensor (TSIS), different proxy representations of sunspot darkening and facular brightening, including the improved composite record of Mg II index being developed as part of the European-led SOlar Irradiance Data exploitation (SOLID) project, and to expand the uncertainty estimates to include model assumptions.

  2. Are solar spectral variations a drive for climatic change

    NASA Technical Reports Server (NTRS)

    Pollack, J. R.; Borucki, W. J.; Toon, O. B.

    1979-01-01

    The effects of UV variations on atmospheric ozone content and climate for time scales encompassing the 27-day solar rotation period, the sunspot period, twice the solar magnetic, and also longer time periods are examined. The studies of the relationship between solar UV variations, atmospheric ozone content and atmospheric temperatures were conducted by estimating the impact of such variations on tropospheric temperature. The total luminosity constant is then held and the dependence of the ozone variations on the forcing period is calculated. It is concluded that solar UV variations on time scales of weeks to months occasionally perturb total ozone and stratospheric temperatures by noticeable amounts but result in only minor changes in the troposphere.

  3. 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…

  4. Solar spectral irradiance observations between 200 and 360 NM made during the Atlas 1 mission: Comparisons between the SOLSPEC, SUSIM, and SSBUV measurements

    NASA Technical Reports Server (NTRS)

    Thuillier, G. O.; VanHoosier, M. E.; Cebula, R. P.

    1995-01-01

    The SOLSPEC, SSBUV, and SUSIM spectrometers observed the solar spectral irradiance simultaneously during the ATLAS-1 mission flown on board the Space Shuttle in March 1992. The three instruments use different methods and means of absolute calibration and were calibrated pre- and post-flight. The three data sets are reported from 200-360 nm at 1.1 nm resolution. The method of comparing the three independent data sets will be discussed. The importance of a common precise wavelength scale will be shown when comparing the data in the wavelength region of the strong Fraunhofer lines. The consistency of the three measurements is better than 5%. The fact that the calibrations of the three instruments were based on three independent national standards ensures that the absolute solar spectral irradiance in the range of 200-360 nm is now known with an accuracy of better than 5%. The data taken from this mission are compared with solar observations from other space based missions.

  5. Recent Progress and Spectral Robustness Study for Mechanically Stacked Multi-junction Solar Cells

    NASA Astrophysics Data System (ADS)

    Zhao, Lu; Flamand, Giovanni; Poortmans, Jef

    2010-10-01

    Multi-terminal mechanically stacked multi-junction solar cells are an attractive candidate for terrestrial concentrator photovoltaics applications. Unlike monolithically integrated multi-junction solar cells which require current matching, all the available photon currents can be fully extracted from each junction of a mechanically stacked solar cell. Therefore, it has a high performance potential, and more importantly is less sensitive to spectrum variations. Lower losses due to current mismatch translate into a higher annual energy output for the mechanical stack. This paper presents the baseline processing developed at imec for the mechanical stacking process, and the most recent cell results by means of this technology. A GaAs-Ge dual-junction mechanically stacked multi-junction solar cell is demonstrated, with 24.7% plus 2.52% under AM1.5g, and 27.7% plus 4.42% under 30Suns concentration. In addition, spectral sensitivity is studied for both monolithically stacked and mechanically stacked solar cells, to learn the influence of spectrum variations on multi-junction solar cell performance. SMARTS model is used to predict the spectral irradiances, with solar radiation and meteorological elements from typical meteorological year 3 (TMY3) data set. The generated spectra are then fed into TCAD numerical simulation tool, to simulate the device performance. The simulation results show a reduced spectral sensitivity for mechanically stacked cell, and there is a 6% relative gain in annual energy production for the site studied (Las Vegas), compared with the monolithic stack.

  6. Total-light imager with flat spectral response for solar photometric measurements.

    PubMed

    Foukal, P; Libonate, S

    2001-03-01

    Certain applications in imaging photometry and radiometry require a telescope-detector system with (preferably constant) response over a wide spectral range from the ultraviolet through the infrared. We describe the design and characterization of the Solar Bolometric Imager (SBI), a 30-cm-aperture Dall-Kirkham telescope combined with a gold-blacked, 80, 000-element thermal array detector. Our SBI prototype provides spectrally uniform imaging in total solar light (0.28-2.6 mum) of heat-flow inhomogeneities at the solar photosphere, with better than 5-arc sec angular resolution over a 6.5 x 13 arc min field of view. A balloon-borne SBI would avoid most atmospheric transmission variation over this spectral range, enabling accurate study of the sources of total irradiance variation. PMID:18357099

  7. A Comparison of the First Solar EUV Irradiance Measurements from the SDO/EVE EUV Spectrophotometer (ESP) with the SOHO/CELIAS Solar EUV Monitor (SEM) Absolute Solar EUV Irradiance

    NASA Astrophysics Data System (ADS)

    Didkovsky, Leonid; Judge, Darrell; Wieman, Seth; Woods, Thomas; Eparvier, Francis; Jones, Andrew

    First light measurements from the SDO/EVE EUV Spectrophotometer (ESP) are calibrated based on both ESP pre-flight radiometric calibration and the SDO EVE calibration rocket un-derflight (5 May 2010) measurements obtained with the ESP and Multiple EUV Grating Spec-trometers (MEGS), which are clones of the SDO EVE onboard instruments. SDO/EVE/ESP absolute solar EUV irradiances are compared with the SOHO/CELIAS Solar EUV Monitor (SEM) data to provide uninterrupted EUV measurements of solar irradiances since 1996. The continuing EUV measurements from SDO/EVE/ESP will advance our study of long-and short-term solar EUV variability, improve existing solar EUV irradiance models, and use as input for improving ionosphere and thermosphere model results.

  8. 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).

  9. Ocean color spectral variability studies using solar-induced chlorophyll fluorescence

    NASA Technical Reports Server (NTRS)

    Hoge, Frank E.; Swift, Robert N.

    1987-01-01

    It is suggested that chlorophyll-induced ocean color spectral variability can be studied using only a passive airborne spectroradiometer instrument, with solar-induced chlorophyll fluorescence used as the standard against which all correlations are performed. The intraspectral correlation (ISC) method is demonstrated with results obtained during an airborne mapping mission in the New York Bight. The curvature algorithm is applied to the solar-induced chlorophyll fluorescence at about 690 nm, and good agreement is found with results obtained using active-passive correlation spectroscopy. The ISC method has application to spectral variability and resulting chlorophyll concentration measurement in different environmental conditions and in different water types.

  10. Antireflection treatment of thickness sensitive spectrally selective (TSSS) paints for thermal solar absorbers

    SciTech Connect

    Lundh, M.; Waeckelgaard, E.; Blom, T.

    2010-01-15

    There are several methods to produce solar absorbers, and one cheap alternative is painted absorbers, preferably painted with a spectrally selective paint. The optical properties of Thickness Sensitive Spectrally Selective (TSSS) paints are, however, limited by the thickness of the paint layer. In this study it is shown that the solar absorptance of two commercial TSSS paints can be increased between 0.01 and 0.02 units with an antireflection treatment using a silicon dioxide layer deposited from silica-gel. It was found that the thermal emittance (100 C) did not change significantly after the treatment. (author)

  11. Spectral analysis and modeling of solar flares chromospheric condensation

    NASA Astrophysics Data System (ADS)

    Cauzzi, Gianna; Graham, David; Kowalski, Adam; Zangrilli, Luca; Simoes, Paulo; Allred, Joel C.

    2016-05-01

    We follow up on our recent analysis of the X1.1 flare SOL2014-09-10T17:45, where we studied the impulsive phase dynamics of tens of individual flaring "kernels", in both coronal (Fe XXI) and chromospheric (MgII) lines observed at high cadence with IRIS.We concentrate here on the chromospheric aspect of the phenomenon, extending the analysis to multiple spectral lines of Mg II, Fe II, Si I, C II. We show that many flaring kernels display high velocity downflows in the spectra of all these chromospheric lines, exhibiting distinct, transient and strongly redshifted spectral components.From modeling using RADYN with the thick-target interpretation, the presence of two spectral components appears to be consistent with a high flux beam of accelerated electrons, characterized by a hard spectrum. In particular the highest energy electrons heat the denser, lower layers of the atmosphere, while the bulk of the beam energy, deposited higher in the atmosphere, is sufficient to produce chromospheric evaporation with a corresponding condensation.

  12. UV-VIS-IR Spectral Responsivity Measurement System for Solar Cells

    SciTech Connect

    Field, H.

    1998-11-12

    NREL's PV Cell and Module Performance Characterization group has built a new spectral responsivity measurement system for solar cells. It uses a xenon arc lamp source, a single, grating monochrometer, and a fiber-optic bundle to couple the monochromatic light to the test device. The system has a spectral bandwidth of 2 nm, minimum spot diameter of 1.6 mm, a spectral range of 280-1330 nm, and uncertainty better than {+-}3% over most of this range. It is capable of incorporating light bias with intensities exceeding one sun. This paper discusses the system's features, capabilities, calibration, and measurement uncertainties.

  13. Radiation Dose Assessments of Solar Particle Events with Spectral Representation at High Energies for the Improvement of Radiation Protection

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Hee Y.; Atwell, William; Tylka, Allan J.; Dietrich, William; Cucinotta, Francis A.

    For radiation dose assessments of major solar particle events (SPEs), spectral functional forms of SPEs have been made by fitting available satellite measurements up to 100 MeV. However, very high-energy protons (above 500 MeV) have been observed with neutron monitors (NMs) in ground level enhancements (GLEs), which generally present the most severe radiation hazards to astronauts. Due to technical difficulties in converting NM data into absolutely normalized fluence measurements, those functional forms were made with little or no use of NM data. A new analysis of NM data has found that a double power law in rigidity (the so-called Band function) generally provides a satisfactory representation of the combined satellite and NM data from 10 MeV to 10 GeV in major SPEs (Tylka and Dietrich, the 31st International Cosmic Ray Conference, Lodz, Poland, July 7-15, 2009). We use the Band function fits to re-assess human exposures from large SPEs. Using different spectral representations of large SPEs, variations of exposure levels were compared. The results can be applied to the development of approaches of improved radiation protection for astronauts, as well as the optimization of mission planning and shielding for future space missions.

  14. Radiation Dose Assessments of Solar Particle Events with Spectral Representation at High Energies for the Improvement of Radiation Protection

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee; Atwell, William; Tylka, Allan J.; Dietrich, William F.; Cucinotta, Francis A.

    2010-01-01

    For radiation dose assessments of major solar particle events (SPEs), spectral functional forms of SPEs have been made by fitting available satellite measurements up to approx.100 MeV. However, very high-energy protons (above 500 MeV) have been observed with neutron monitors (NMs) in ground level enhancements (GLEs), which generally present the most severe radiation hazards to astronauts. Due to technical difficulties in converting NM data into absolutely normalized fluence measurements, those functional forms were made with little or no use of NM data. A new analysis of NM data has found that a double power law in rigidity (the so-called Band function) generally provides a satisfactory representation of the combined satellite and NM data from approx.10 MeV to approx.10 GeV in major SPEs (Tylka & Dietrich 2009). We use the Band function fits to re-assess human exposures from large SPEs. Using different spectral representations of large SPEs, variations of exposure levels were compared. The results can be applied to the development of approaches of improved radiation protection for astronauts, as well as the optimization of mission planning and shielding for future space missions.

  15. Absolute oscillator strengths for lines of neutral cobalt between 2276 A and 9357 A and a redetermination of the solar cobalt abundance

    SciTech Connect

    Cardon, B.L.; Smith, P.L.; Scalo, J.M.; Testerman, L.; Whaling, W.

    1982-09-01

    Absolute oscillator strengths of neutral cobalt have been determined from hook measurements for 159 transitions and emission intensity measurements for 314 transitions between 2276 A and 9357 A. Ninety-five of these transitions were subjected to the procedure developed by Cardon, Smith, and Whaling which fits combined absorption and emission data to a set of consistent, optimum, relative oscillator strengths and upper level lifetimes. These relative values were normalized to the radiative lifetimes of Figger et al. and of Marek and Vogt obtained by pulsed laser fluorescence. Absolute oscillator strengths for 362 transitions and 36 lifetimes were determined. Typical uncertainties in the reported absolute oscillator strengths are +- 15-25% (2/3 confidence level). Equivalent widths were obtained for nineteen solar cobalt lines with the McMath solar telescope at Kitt Peak National Observatory. These widths were used to redetermine the solar cobalt abundance, assuming the photospheric model of Holweger and a microturbulence velocity of 1.0 km s/sup -1/. The adopted solar cobalt abundance is the mean value log +12 = 4.92 +- 0.08 ( +- 19%), from the 19 cobalt transitions. This value is in excellent agreement with the solar values of Ross and Aller, of Biemont, and of Holweger and that of Cameron for carbonaceous chondrites.

  16. Absolute oscillator strengths for lines of neutral cobalt between 2276 A and 9357 A and a redetermination of the solar cobalt abundance

    NASA Astrophysics Data System (ADS)

    Cardon, B. L.; Smith, P. L.; Scalo, J. M.; Testerman, L.; Whaling, W.

    1982-09-01

    Absolute oscillator strengths of neutral cobalt have been determined from hook measurements for 159 transitions and emission intensity measurements for 314 transitions between 2276 Å and 9357 Å. Ninety-five of these transitions were subjected to the procedure developed by Cardon, Smith, and Whaling which fits combined absorption and emission data to a set of consistent, optimum, relative oscillator strengths and upper level lifetimes. These relative values were normalized to the radiative lifetimes of Figger et al. and of Marek and Vogt obtained by pulsed laser fluorescence. Absolute oscillator strengths for 362 transitions and 36 lifetimes were determined. Typical uncertainties in the reported absolute oscillator strengths are ±15-25% (2/3 confidence level). Equivalent widths were obtained for nineteen solar cobalt lines with the McMath solar telescope at Kitt Peak National Observatory. These widths were used to redetermine the solar cobalt abundance, assuming the photospheric model of Holweger and a microturbulence velocity of 1.0 km s-1. The adopted solar cobalt abundance is the mean value log Co/NH> + 12 = 4.92 ± 0.08 (±19%), from the 19 cobalt transitions. This value is in excellent agreement with the solar values of Ross and Aller, of Biemont, and of Holweger and that of Cameron for carbonaceous chondrites.

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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

  2. Observations of Solar Spectral Irradiance Change During Cycle 22 from NOAA-9 SBUV/2

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Cebula, Richard P.; Hilsenrath, Ernest

    2003-01-01

    The NOM-9 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument is one of a series of instruments providing daily solar spectral irradiance measurements in the middle and near ultraviolet since 1978. The SBUV/2 instruments are primarily designed to measure stratospheric profile and total column ozone, using the directional albedo as the input to the ozone processing algorithm. As a result, the SBUV/2 instrument does not have onboard monitoring of all time-dependent response changes. We have applied internal comparisons and vicarious (external) comparisons to determine the long-term instrument characterization for NOAA-9 SBUV/2 to derive accurate solar spectral irradiances from March 1985 to May 1997 spanning two solar cycle minima with a single instrument. The NOAA-9 data show an amplitude of 9.3(+/- 2.3)% (81-day averaged) at 200-205 nm for solar cycle 22. This is consistent with the result of (Delta)F(sub 200-205) = 8.3(+/- 2.6)% for cycle 21 from Nimbus-7 SBUV and (Delta)F(sub 200-205) = 10(+/- 2)% (daily values) for cycle 23 from UARS SUSIM. NOAA-9 data at 245-250 nm show a solar cycle amplitude of (Delta)F(sub 245-250) = 5.7(+/- 1.8)%. NOAA-9 SBUV/2 data can be combined with other instruments to create a 25-year record of solar UV irradiance.

  3. The future of solar spectral irradiance in the ultraviolet with the SOLSIM double-monochromator

    NASA Astrophysics Data System (ADS)

    Damé, Luc; Bolsee, David; Rouanet, Nicolas; Gilbert, Pierre

    2016-07-01

    Solar Spectral Irradiance (SSI) in the UV, and its variability, are of prime importance to quantify the solar forcing on the climate through radiation and their interactions with the local stratosphere, noticeably through the "top-down" mechanism amplifying UV solar forcing on the climate (UV affects stratospheric dynamics and temperatures, altering interplanetary waves and weather patterns both poleward and downward to the lower stratosphere and tropopause regions). SOLSIM (Solar Spectral Irradiance Monitor) is a newly designed double-monochromator instrument covering the 170 - 340 nm ultraviolet spectral range. It is an enhanced and optimized version of the previously flown SOLSPEC instrument externally mounted on the Columbus module of the International Space Station. While SOLSPEC had 3 double-monochromators to cover the UV to the IR, the SOLSIM spectrometer is covering only the UV but with an almost constant 0.65 nm spectral resolution from 170 to 340 nm. To avoid thermal issues with the instrument, a sun-synchronous polar orbit 18h-6h (for almost constant observing) is preferred to the Space Station (SOLSIM is part of the model payload of the SUITS/SWUSV proposed mission). Characteristics, performances and calibrations foreseen for this new generation SSI instrument will be presented.

  4. Climate variability related to the 11 year solar cycle as represented in different spectral solar irradiance reconstructions

    NASA Astrophysics Data System (ADS)

    Kruschke, Tim; Kunze, Markus; Misios, Stergios; Matthes, Katja; Langematz, Ulrike; Tourpali, Kleareti

    2016-04-01

    Advanced spectral solar irradiance (SSI) reconstructions differ significantly from each other in terms of the mean solar spectrum, that is the spectral distribution of energy, and solar cycle variability. Largest uncertainties - relative to mean irradiance - are found for the ultraviolet range of the spectrum, a spectral region highly important for radiative heating and chemistry in the stratosphere and troposphere. This study systematically analyzes the effects of employing different SSI reconstructions in long-term (40 years) chemistry-climate model (CCM) simulations to estimate related uncertainties of the atmospheric response. These analyses are highly relevant for the next round of CCM studies as well as climate models within the CMIP6 exercise. The simulations are conducted by means of two state-of-the-art CCMs - CESM1(WACCM) and EMAC - run in "atmosphere-only"-mode. These models are quite different with respect to the complexity of the implemented radiation and chemistry schemes. CESM1(WACCM) features a chemistry module with considerably higher spectral resolution of the photolysis scheme while EMAC employs a radiation code with notably higher spectral resolution. For all simulations, concentrations of greenhouse gases and ozone depleting substances, as well as observed sea surface temperatures (SST) are set to average conditions representative for the year 2000 (for SSTs: mean of decade centered over year 2000) to exclude anthropogenic influences and differences due to variable SST forcing. Only the SSI forcing differs for the various simulations. Four different forcing datasets are used: NRLSSI1 (used as a reference in all previous climate modeling intercomparisons, i.e. CMIP5, CCMVal, CCMI), NRLSSI2, SATIRE-S, and the SSI forcing dataset recommended for the CMIP6 exercise. For each dataset, a solar maximum and minimum timeslice is integrated, respectively. The results of these simulations - eight in total - are compared to each other with respect to their

  5. Spectral scaling laws of solar wind fluctuations at 1 AU: Part 2

    SciTech Connect

    Podesta, John J.

    2013-06-13

    In-situ measurements of solar wind fluctuations at 1 AU show that the reduced energy spectrum, equal to the sum of the reduced kinetic plus magnetic energy spectra, is characterized by a power-law scaling k{sup -{alpha}} in the inertial range with an average spectral exponent {alpha} Asymptotically-Equal-To 3/2, a result confirmed by independent analyses using data from different spacecraft. Magnetic field and electron density spectra at kinetic scales {rho}{sup -1}{sub i} < k < {rho}{sup -1}{sub e} both have a spectral index of approximately 2.7. These and other recent observations of spectral scaling laws in the solar wind using single spacecraft measurements are briefly reviewed. The first part of this review, Part 1, is contained in a separate paper in these proceedings.

  6. Tropospheric Response to Estimated Spectrally Discriminated Solar Forcing Over the Past 500 Years

    NASA Technical Reports Server (NTRS)

    Rind, David; Hansen, James E. (Technical Monitor)

    2000-01-01

    The GISS Global Climate Middle Atmosphere Model (GCMAM) is used to investigate the effect of estimated solar irradiance changes on climate for the past 500 years. This model is employed to allow the impact of UV variations on the stratosphere to affect the troposphere via wave-mean flow interactions. Multiple experiments are done with only a total solar irradiance change (peaking at 0.2 percent from the Maunder Minimum to today); with estimated spectrally-varying irradiance changes (i.e., peak changes of 0.7 percent in the UV, 0.2 percent in the visible and near IR; and 0.07 percent in the IR greater than 1 micron); and the spectrally-varying changes in conjunction with model calculated ozone responses in the stratosphere. Results of the varying temperature patterns and radiation response will be discussed. Of interest is whether the different methods of forcing the solar-induced climate change produce different spatial surface temperature signatures, particularly ones that can be differentiated from greenhouse gas warming. In preliminary tests, spectrally-varying solar forcing with induced ozone changes for solar maximum minus solar minimum conditions results in a temperature signal that is primarily at high latitudes.The high latitude response arises due to solar/ozone-induced alterations in the stratospheric wind field that affect planetary wave propagation from the troposphere, and alter tropospheric advection patterns. In contrast, forcing by total solar irradiance changes produces significant response at low and subtropical latitudes as well, driven by water vapor and cloud feedbacks to the radiative perturbation.

  7. Temperature Responses to Spectral Solar Variability on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Cahalan, Robert; Wen, Guoyong; Pilewskie, Peter; Harder, Jerald

    2010-05-01

    We apply two scenarios of 11-year solar spectral forcing, namely SIM-based out-of-phase variations and proxy-based in-phase variations, as input to a time-dependent radiative-convective model (RCM), and also to the GISS modelE GCM. For both scenarios, and both models, we find that the maximum temperature response occurs in the upper stratosphere, and temperature responses decrease downward to the surface. The upper stratospheric temperature peak-to-peak responses to out-of-phase solar forcing are ~0.6 K in RCM and ~0.9 K over the tropical region in GCM simulations, a factor of ~5 times as large as responses to in-phase solar forcing. Stratospheric responses are in-phase with TSI (Total Solar Irradiance) variations. The modeled upper stratospheric temperature response to the SORCE SIM observed SSI (Spectral Solar Irradiance) forcing resembles 11-year temperature variations observed with HALOE (Halogen Occultation Experiment). Surface responses to the two SSI scenarios are small for both RCM and GCM studies, as compared to stratospheric responses. Though solar irradiance variations on centennial time scale are not well known, the two scenarios of reconstructed TSI time series (i.e., one based on 11-year cycles with background [Lean 2000] and the second from flux transport that has much less background change [Wang, Lean, and Sheeley, 2005]) provide a range of variations of TSI on centennial time scales. We apply phase relations among different spectral irradiance bands both from SIM observation and proxy reconstructions to the two scenarios of historical TSI. The spectral solar forcing is used to drive the RCM. The updated atmosphere and ocean mixed coupled RCM including diffusion to deep-ocean provides a first-order estimate of climate response. We report the different responses of stratosphere, troposphere, and ocean surface to these 4 scenarios of centennial spectral solar forcing. We further discuss the mechanisms for atmosphere-ocean and stratosphere

  8. Spectral estimates of intercepted solar radiation by corn and soybean canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Brooks, C. C.; Daughtry, C. S. T.; Bauer, M. E.; Vanderbilt, V. C.

    1982-01-01

    Attention is given to the development of methods for combining spectral and meteorological data in crop yield models which are capable of providing accurate estimates of crop condition and yields throughout the growing season. The present investigation is concerned with initial tests of these concepts using spectral and agronomic data acquired in controlled experiments. The data were acquired at the Purdue University Agronomy Farm, 10 km northwest of West Lafayette, Indiana. Data were obtained throughout several growing seasons for corn and soybeans. Five methods or models for predicting yields were examined. On the basis of the obtained results, it is concluded that estimating intercepted solar radiation using spectral data is a viable approach for merging spectral and meteorological data in crop yield models.

  9. Large-area irradiance-mode spectral response measurements of solar cells by a light-emitting, diode-based integrating sphere source.

    PubMed

    Hamadani, Behrang H; Roller, John; Shore, Andrew M; Dougherty, Brian; Yoon, Howard W

    2014-06-01

    An irradiance-mode absolute differential spectral response (SR) measurement system based on a light emitting diode (LED) array is described. The LEDs are coupled to an integrating sphere whose output irradiance is uniform to better than 2% over an area of 160 mm by 160 mm. SR measurements of solar cells when subject to diffuse irradiation, as provided by the integrating sphere, are compared with collimated irradiance SR measurements. Issues originating from the differences in angular response of the reference versus the test cells are also investigated. The SR curves of large-area cells with dimensions of up to 155 mm are measured and then used to calculate the cell's short circuit current (I(sc)), if illuminated by a defined solar spectrum. The resulting values of I(sc) agree well with the values obtained from secondary measurements. PMID:24922435

  10. THE INFLUENCE OF INTERMITTENCY ON THE SPECTRAL ANISOTROPY OF SOLAR WIND TURBULENCE

    SciTech Connect

    Wang, Xin; Tu, Chuanyi; He, Jiansen; Wang, Linghua; Marsch, Eckart

    2014-03-01

    The relation between the intermittency and the anisotropy of the power spectrum in the solar wind turbulence is studied by applying the wavelet technique to the magnetic field and flow velocity data measured by the WIND spacecraft. It is found that when the intermittency is removed from the turbulence, the spectral indices of the power spectra of the field and velocity turn out to be independent of the angle θ{sub RB} between the direction of the local scale-dependent background magnetic field and the heliocentric direction. The spectral index becomes –1.63 ± 0.02 for magnetic field fluctuations and –1.56 ± 0.02 for velocity fluctuations. These results may suggest that the recently found spectral anisotropy of solar wind power spectra in the inertial range could result from turbulence intermittency. As a consequence, a new concept is here proposed of an intermittency-associated sub-range of the inertial domain adjacent to the dissipation range. Since spectral anisotropy was previously explained as evidence for the presence of a ''critical balance'' type turbulent cascade, and also for the existence of kinetic Alfvén waves, this new finding may stimulate fresh thoughts on how to analyze and interpret solar wind turbulence and the associated heating.

  11. Shifting the Sun: Solar Spectral Conversion and Extrinsic Sensitization in Natural and Artificial Photosynthesis

    PubMed Central

    Tyystjärvi, Esa; Méndez‐Ramos, Jorge; Müller, Frank A.; Zhang, Qinyuan

    2015-01-01

    Solar energy harvesting is largely limited by the spectral sensitivity of the employed energy conversion system, where usually large parts of the solar spectrum do not contribute to the harvesting scheme, and where, of the contributing fraction, the full potential of each photon is not efficiently used in the generation of electrical or chemical energy. Extrinsic sensitization through photoluminescent spectral conversion has been proposed as a route to at least partially overcome this problem. Here, we discuss this approach in the emerging context of photochemical energy harvesting and storage through natural or artificial photosynthesis. Clearly contrary to application in photovoltaic energy conversion, implementation of solar spectral conversion for extrinsic sensitization of a photosynthetic machinery is very straightforward, and—when compared to intrinsic sensitization—less‐strict limitations with regard to quantum coherence are seen. We now argue the ways in which extrinsic sensitization through photoluminescent spectral converters will—and will not—play its role in the area of ultra‐efficient photosynthesis, and also illustrate how such extrinsic sensitization requires dedicated selection of specific conversion schemes and design strategies on system scale. PMID:27774377

  12. The Influence of Intermittency on the Spectral Anisotropy of Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Tu, Chuanyi; He, Jiansen; Marsch, Eckart; Wang, Linghua

    2014-03-01

    The relation between the intermittency and the anisotropy of the power spectrum in the solar wind turbulence is studied by applying the wavelet technique to the magnetic field and flow velocity data measured by the WIND spacecraft. It is found that when the intermittency is removed from the turbulence, the spectral indices of the power spectra of the field and velocity turn out to be independent of the angle θRB between the direction of the local scale-dependent background magnetic field and the heliocentric direction. The spectral index becomes -1.63 ± 0.02 for magnetic field fluctuations and -1.56 ± 0.02 for velocity fluctuations. These results may suggest that the recently found spectral anisotropy of solar wind power spectra in the inertial range could result from turbulence intermittency. As a consequence, a new concept is here proposed of an intermittency-associated sub-range of the inertial domain adjacent to the dissipation range. Since spectral anisotropy was previously explained as evidence for the presence of a "critical balance" type turbulent cascade, and also for the existence of kinetic Alfvén waves, this new finding may stimulate fresh thoughts on how to analyze and interpret solar wind turbulence and the associated heating.

  13. GISS GCMAM Modeled Climate Responses to Total and Spectral Solar Forcing on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Wen, G.; Cahalan, R. F.; Rind, D. H.; Jonas, J.; Pilewskie, P.; Harder, J. W.; Krivova, N.

    2014-12-01

    We examine the influence of the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral Irradiance Monitor) observed spectral solar irradiance (SSI) variations on Earth's climate. We apply two reconstructed spectral solar forcing scenarios, one SIM based, the other based on the SATIRE (Spectral And Total Irradiance REconstruction) model, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to examine the climate responses on decadal and centennial time scales. We show that the atmosphere has different temperature, ozone, and dynamic responses to the two solar spectral forcing scenarios, even when the variations in TSI (Total Solar Irradiance) are the same. We find that solar variations under either scenario contribute a small fraction of the observed temperature increase since the industrial revolution. The trend of global averaged surface air temperature response to the SIM-based solar forcing is 0.02 °C/century, about half of the temperature trend to the SATIRE-based SSI. However the temporal variation of the surface air temperature for the SIM-based solar forcing scenario is much larger compared to its SATIRE counterpart. Further research is required to examine TSI and SSI variations in the ascending phase of solar cycle 24, to assess their implications for the solar influence on climate.

  14. GISS GCMAM Modeled Climate Responses to Total and Spectral Solar Forcing on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Wen, Guoyong; Cahalan, Robert; Rind, David; Jonas, Jeffrey; Pilewskie, Peter; Harder, Jerry

    2014-05-01

    We examine the influence of the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral Irradiance Monitor) observed spectral solar irradiance (SSI) variations on Earth's climate. We apply two reconstructed spectral solar forcing scenarios, one SIM based, the other based on the SATIRE (Spectral And Total Irradiance REconstruction) model, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to examine the climate responses on decadal and centennial time scales. We show that the atmosphere has different temperature, ozone, and dynamic responses to the two solar spectral forcing scenarios, even when the variations in TSI (Total Solar Irradiance) are the same. We find that solar variations under either scenario contribute a small fraction of the observed temperature increase since the industrial revolution. The trend of global averaged surface air temperature response to the SIM-based solar forcing is 0.02 °C/century, about half of the temperature trend to the SATIRE-based SSI. However the temporal variation of the surface air temperature for the SIM-based solar forcing scenario is much larger compared to its SATIRE counterpart. Further research is required to examine TSI and SSI variations in the ascending phase of solar cycle 24, to assess their implications for the solar influence on climate.

  15. Free Flyer Total and Spectral Solar Irradiance Sensor (TSIS) and Climate Services Mission

    NASA Technical Reports Server (NTRS)

    Cahalan, R.; Pilewskie, P.; Woods, T.

    2012-01-01

    NOAA's planned Total and Spectral Solar Irradiance Sensor (TSIS) mission will fly along with the NOAA user service payloads Advanced Data Collection System (ADCS) and Search and Rescue Satellite Aided Tracking (SARSAT). In ' order to guarantee continuity in the 33-year solar irradiance climate data record, TSIS must be launched in time to overlap with current on-orbit solar irradiance instruments. Currently TSIS is moving towards a launch rcadinss date of January 2015. TSIS provides for continuation of the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) ,currently onboard NASA's Solar Radiation and Climate Experiment (SORCE) platform, launched in January 2003. The difficulty of ensuring continuity has increased due to the launch failure of NASA's Glory mission with its improved TIM. Achieving the needed overlap must now rely on extending SORCE. and maintaining the TSIS schedule. TSIS is one component of a NASA-NOAA joint program (JPSS) planned to transition certain climate observations to operational mode. We summarize issues of continuity, improvements being made to the TIM and 81M sensors, and plans to provide for traceability of total and spectral irradiance measurements to ground-based cryogenic standards.

  16. OBSERVED VARIABILITY OF THE SOLAR Mg II h SPECTRAL LINE

    SciTech Connect

    Schmit, D.; Pontieu, B. De; Bryans, P.; McIntosh, S.; Leenaarts, J.; Carlsson, M.

    2015-10-01

    The Mg ii h and k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the photosphere to the upper chromosphere. We use a double-Gaussian model to fit the Mg ii h profile for a full-Sun mosaic data set taken on 2014 August 24. We use the ensemble of high-quality profile fits to conduct a statistical study on the variability of the line profile as it relates the magnetic structure, dynamics, and center-to-limb viewing angle. The average internetwork profile contains a deeply reversed core and is weakly asymmetric at h2. In the internetwork, we find a strong correlation between h3 wavelength and profile asymmetry as well as h1 width and h2 width. The average reversal depth of the h3 core is inversely related to the magnetic field. Plage and sunspots exhibit many profiles that do not contain a reversal. These profiles also occur infrequently in the internetwork. We see indications of magnetically aligned structures in plage and network in statistics associated with the line core, but these structures are not clear or extended in the internetwork. The center-to-limb variations are compared to predictions of semi-empirical model atmospheres. We measure a pronounced limb darkening in the line core that is not predicted by the model. The aim of this work is to provide a comprehensive measurement baseline and preliminary analysis on the observed structure and formation of the Mg ii profiles observed by IRIS.

  17. Observed Variability of the Solar Mg II h Spectral Line

    NASA Astrophysics Data System (ADS)

    Schmit, D.; Bryans, P.; De Pontieu, B.; McIntosh, S.; Leenaarts, J.; Carlsson, M.

    2015-10-01

    The Mg ii h&k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the photosphere to the upper chromosphere. We use a double-Gaussian model to fit the Mg ii h profile for a full-Sun mosaic data set taken on 2014 August 24. We use the ensemble of high-quality profile fits to conduct a statistical study on the variability of the line profile as it relates the magnetic structure, dynamics, and center-to-limb viewing angle. The average internetwork profile contains a deeply reversed core and is weakly asymmetric at h2. In the internetwork, we find a strong correlation between h3 wavelength and profile asymmetry as well as h1 width and h2 width. The average reversal depth of the h3 core is inversely related to the magnetic field. Plage and sunspots exhibit many profiles that do not contain a reversal. These profiles also occur infrequently in the internetwork. We see indications of magnetically aligned structures in plage and network in statistics associated with the line core, but these structures are not clear or extended in the internetwork. The center-to-limb variations are compared to predictions of semi-empirical model atmospheres. We measure a pronounced limb darkening in the line core that is not predicted by the model. The aim of this work is to provide a comprehensive measurement baseline and preliminary analysis on the observed structure and formation of the Mg ii profiles observed by IRIS.

  18. The Measurement of the Solar Spectral Irradiance Variability at 782 nm during the Solar Cycle 24 using the SES on-board PICARD

    NASA Astrophysics Data System (ADS)

    Meftah, Mustapha; Hauchecorne, Alain; Irbah, Abdanour; Bekki, Slimane

    2016-04-01

    A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the PICARD satellite. The SES sensor produced an image of the Sun at 782+/-5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782nm from 2010 to 2014. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm during the solar cycle 24. Comparisons will be made with Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) semi-empirical model and with the Spectral Irradiance Monitor instrument (SIM) on-board the Solar Radiation and Climate Experiment satellite (SORCE). These data will help to improve the representation of the solar forcing in the IPSL Global Circulation Model.

  19. Spectral structures and their generation mechanisms for solar radio type-I bursts

    SciTech Connect

    Iwai, K.; Miyoshi, Y.; Masuda, S.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2014-07-01

    The fine spectral structures of solar radio type-I bursts were observed by the solar radio telescope AMATERAS. The spectral characteristics, such as the peak flux, duration, and bandwidth, of the individual burst elements were satisfactorily detected by the highly resolved spectral data of AMATERAS with the burst detection algorithm that is improved in this study. The peak flux of the type-I bursts followed a power-law distribution with a spectral index of 2.9-3.3, whereas their duration and bandwidth were distributed more exponentially. There were almost no correlations between the peak flux, duration, and bandwidth. That means there was no similarity in the shapes of the burst spectral structures. We defined the growth rate of a burst as the ratio between its peak flux and duration. There was a strong correlation between the growth rate and peak flux. These results suggest that the free energy of type-I bursts that is originally generated by nonthermal electrons is modulated in the subsequent stages of the generation of nonthermal electrons, such as plasma wave generation, radio wave emissions, and propagation. The variation of the timescale of the growth rate is significantly larger than that of the coronal environments. These results can be explained by the situation wherein the source region may have the inhomogeneity of an ambient plasma environment, such as the boundary of open and closed field lines, and the superposition of entire emitted bursts was observed by the spectrometer.

  20. A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy over Six-Month Intervals

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

    2015-10-01

    A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is examining the total energy of the irradiance variation during 6-month periods. This duration is selected because a solar active region typically appears suddenly and then takes 5 to 7 months to decay and disperse back into the quiet-Sun network. The solar outburst energy, which is defined as the irradiance integrated over the 6-month period and thus includes the energy from all phases of active region evolution, could be considered the primary cause for the irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the energy spectral variation may provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (6-month) variations from the Solar Radiation and Climate Experiment (SORCE) instruments can be decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These excess and deficit variations are fit over 6-month intervals every 2 months over the mission, and these fitted variations are then integrated over time for the 6-month energy. The dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1400 - 1600 nm range, with all other wavelengths having in-phase variations.

  1. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators

    PubMed Central

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2015-01-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300−2500 nm at incidence angles 15–60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0–60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350–1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article “Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators” in Solar Energy Materials and Solar Cells. PMID:26862556

  2. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

    PubMed

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2016-03-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

  3. Measured and modeled trends in the solar spectral irradiance variability using the SORCE SIM and SOLSTICE instruments

    NASA Astrophysics Data System (ADS)

    Harder, J. W.; Fontenla, J. M.; Rast, M. P.; Snow, M. A.; Woods, T. N.

    2011-12-01

    The Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) measures solar spectral variability in the 200-2400 nm range accounting for about 97% of the total solar irradiance (TSI). SIM concurrently measures ultraviolet variability from 200-310 nm with the higher spectral resolution Solar-Stellar Irradiance Comparison Experiment (SOLSTICE). These instruments monitored the descending phase of solar cycle 23 and are now continuing these observations in the rising phase of cycle 24. SIM and SOLSTICE observations clearly show rotational modulation of spectral irradiance due to the evolution of dark sunspots and bright faculae that respectively deplete and enhance solar radiation. In addition to this well-known phenomenon, SORCE observations indicate a slower evolutionary trend in solar spectral irradiance (SSI) over solar cycle time-scales that are both in and out of phase with the TSI, with the ultraviolet component indicating significantly larger UV variability than reported from the UARS era instruments. Wavelengths where the brightness temperature is less than Teff = 5770 K are in phase, and where the brightness temperature > Teff in the visible and infrared, the time series show an anti-solar cycle trend. This observation is discussed in terms of the Solar Radiation Physical Modeling (SRPM) program employing solar images from Precision Solar Photometric Telescope (PSPT) that provides the areas of active regions on the solar disk as function of time to generate a modeled SSI time series that is concurrent with the SORCE observations but extending back to solar maximum conditions. Comparative studies of the SIM and SOLSTICE will be presented along with analysis of solar variability derived from SRPM and PSPT.

  4. Pulse Analysis Spectroradiometer System for Measuring the Spectral Distribution of Flash Solar Simulators: Preprint

    SciTech Connect

    Andreas, A. M.; Myers, D. R.

    2008-07-01

    Flashing artificial light sources are used extensively in photovoltaic module performance testing and plant production lines. There are several means of attempting to measure the spectral distribution of a flash of light; however, many of these approaches generally capture the entire pulse energy. We report here on the design and performance of a system to capture the waveform of flash at individual wavelengths of light. Any period within the flash duration can be selected, over which to integrate the flux intensity at each wavelength. The resulting spectral distribution is compared with the reference spectrum, resulting in a solar simulator classification.

  5. SUITS/SWUSV: a small-size mission to address solar spectral variability, space weather and solar-climate relations

    NASA Astrophysics Data System (ADS)

    Damé, Luc; Keckhut, Philippe; Hauchecorne, Alain; Meftah, Mustapha; Bekki, Slimane

    2016-07-01

    We present the SUITS/SWUSV microsatellite mission investigation: "Solar Ultraviolet Influence on Troposphere/Stratosphere, a Space Weather & Ultraviolet Solar Variability" mission. SUITS/SWUSV was developed to determine the origins of the Sun's activity, understand the flaring process (high energy flare characterization) and onset of CMEs (forecasting). Another major objective is to determine the dynamics and coupling of Earth's atmosphere and its response to solar variability (in particular UV) and terrestrial inputs. It therefore includes the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging) the solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance measures from 170 to 400 nm). The mission is proposed on a sun-synchronous polar orbit 18h-6h (for almost constant observing) and proposes a 7 instruments model payload of 65 kg - 65 W with: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg continuum) imaging (sources of variability); SOLSIM (Solar Spectral Irradiance Monitor), a spectrometer with 0.65 nm spectral resolution from 170 to 340 nm; SUPR (Solar Ultraviolet Passband Radiometers), with UV filter radiometers at Lyman-Alpha, Herzberg, MgII index, CN bandhead and UV bands coverage up to 400 nm; HEBS (High Energy Burst Spectrometers), a large energy coverage (a few tens of keV to a few hundreds of MeV) instrument to characterize large flares; EPT-HET (Electron-Proton Telescope - High Energy Telescope), measuring electrons, protons, and heavy ions over a large energy range; ERBO (Earth Radiative Budget and Ozone) NADIR oriented; and a vector magnetometer. Complete accommodation of the payload has been performed on a PROBA type platform very nicely. Heritage is important both for instruments (SODISM and PREMOS on PICARD, LYRA on PROBA-2, SOLSPEC on ISS

  6. Role of spectral non-idealities in the design of solar thermophotovoltaics.

    PubMed

    Lenert, Andrej; Nam, Youngsuk; Bierman, David M; Wang, Evelyn N

    2014-10-20

    To bridge the gap between theoretically predicted and experimentally demonstrated efficiencies of solar thermophotovoltaics (STPVs), we consider the impact of spectral non-idealities on the efficiency and the optimal design of STPVs over a range of PV bandgaps (0.45-0.80 eV) and optical concentrations (1-3,000x). On the emitter side, we show that suppressing or recycling sub-bandgap radiation is critical. On the absorber side, the relative importance of high solar absorptance versus low thermal emittance depends on the energy balance. Both results are well-described using dimensionless parameters weighting the relative power density above and below the cutoff wavelength. This framework can be used as a guide for materials selection and targeted spectral engineering in STPVs.

  7. Recent variability of the solar spectral irradiance and its impact on climate modelling

    NASA Astrophysics Data System (ADS)

    Ermolli, I.; Matthes, K.; Dudok de Wit, T.; Krivova, N. A.; Tourpali, K.; Weber, M.; Unruh, Y. C.; Gray, L.; Langematz, U.; Pilewskie, P.; Rozanov, E.; Schmutz, W.; Shapiro, A.; Solanki, S. K.; Woods, T. N.

    2013-04-01

    The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE

  8. Discussion on the spectral coherence between planetary, solar and climate oscillations: a reply to some critiques

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola

    2014-12-01

    During the last few years a number of works have proposed that planetary harmonics regulate solar oscillations. Also the Earth's climate seems to present a signature of multiple astronomical harmonics. Herein I address some critiques claiming that planetary harmonics would not appear in the data. I will show that careful and improved analysis of the available data do support the planetary theory of solar and climate variation also in the critiqued cases. In particular, I show that: (1) high-resolution cosmogenic 10Be and 14C solar activity proxy records both during the Holocene and during the Marine Interglacial Stage 9.3 (MIS 9.3), 325-336 kyear ago, present four common spectral peaks (confidence level ⪆95 %) at about 103, 115, 130 and 150 years (this is the frequency band that generates Maunder and Dalton like grand solar minima) that can be deduced from a simple solar model based on a generic non-linear coupling between planetary and solar harmonics; (2) time-frequency analysis and advanced minimum variance distortion-less response (MVDR) magnitude squared coherence analysis confirm the existence of persistent astronomical harmonics in the climate records at the decadal and multidecadal scales when used with an appropriate window lenght ( L≈110 years) to guarantee a sufficient spectral resolution to solve at least the major astronomical harmonics. The optimum theoretical window length deducible from astronomical considerations alone is, however, L⪆178.4 years because the planetary frequencies are harmonics of such a period. However, this length is larger than the available 164-year temperature signal. Thus, the best coherence test can be currently made only using a single window as long as the temperature instrumental record and comparing directly the temperature and astronomical spectra as done in Scafetta (J. Atmos. Sol. Terr. Phys. 72(13):951-970, 2010) and reconfirmed here. The existence of a spectral coherence between planetary, solar and climatic

  9. Spectral lines observed in solar flares between 171 and 630 angstroms

    NASA Technical Reports Server (NTRS)

    Dere, K. P.

    1978-01-01

    Several hundred spectral lines emitted in solar flares between 171 and 630 A have been recorded by the Naval Research Laboratory spectroheliograph aboard Skylab. The wavelengths, identifications, and intensity estimates of these lines are presented, based on measurements of all of the suitable flare plates. Nearly 100 new and unidentified lines have been observed. Identifications of three Fe XXI and two Fe XVII lines are suggested.

  10. An evaluation of spectrally selective reflectors (cold mirror membranes) for use with concentrator solar arrays

    NASA Astrophysics Data System (ADS)

    Beauchamp, W. T.; Rancourt, J. D.; Lott, D. R.

    1980-06-01

    Spectrally selective reflector (SSR) coatings on lightweight transparent membranes were evaluated as a method of concentrating light for achieving increased power without suffering severe temperature losses on solar arrays. Analysis and laboratory tests indicate that SSR concentrators are more effective than opaque reflectors with both silicon and GaAs cells for increasing array output. Large area SSR membranes can be produced in roll to roll coaters at cost that will be competitive with other reflecting membranes.

  11. Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Goldstein, Richard M.

    1994-01-01

    Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling.

  12. Voyager 2 solar plasma and magnetic field spectral analysis for intermediate data sparsity

    NASA Astrophysics Data System (ADS)

    Gallana, Luca; Fraternale, Federico; Iovieno, Michele; Fosson, Sophie M.; Magli, Enrico; Opher, Merav; Richardson, John D.; Tordella, Daniela

    2016-05-01

    The Voyager probes are the furthest, still active, spacecraft ever launched from Earth. During their 38 year trip, they have collected data regarding solar wind properties (such as the plasma velocity and magnetic field intensity). Unfortunately, a complete time evolution of the measured physical quantities is not available. The time series contains many gaps which increase in frequency and duration at larger distances. The aim of this work is to perform a spectral and statistical analysis of the solar wind plasma velocity and magnetic field using Voyager 2 data measured in 1979, when the gap density is between the 30% and 50%. For these gap densities, we show the spectra of gapped signals inherit the characteristics of the data gaps. In particular, the algebraic decay of the intermediate frequency range is underestimated and discrete peaks result not from the underlaying data but from the gap sequence. This analysis is achieved using five different data treatment techniques coming from the multidisciplinary context: averages on linearly interpolated subsets, correlation without data interpolation, correlation of linearly interpolated data, maximum likelihood data reconstruction, and compressed sensing spectral estimation. With five frequency decades, the spectra we obtained have the largest frequency range ever computed at five astronomical units from the Sun; spectral exponents have been determined for all the components of the velocity and magnetic field fluctuations. Void analysis is also useful in recovering other spectral properties such as micro and integral scales.

  13. Accounting for spectral albedo, solar light penetration and impurity content in detailed snowpack simulations

    NASA Astrophysics Data System (ADS)

    Dumont, Marie; Lafaysse, Matthieu; Picard, Ghislain; Arnaud, Laurent; Libois, Quentin; Morin, Samuel

    2016-04-01

    The energy balance of the snowpack, driven in particular by its spectral albedo and the penetration depth of solar light, is of primary importance to drive the time evolution of snow on the ground. Here we introduce new developments of the detailed snowpack model SURFEX/ISBA-Crocus (Brun et al., 1992 ; Vionnet et al., 2012) which now includes a spectrally-resolved two-stream calculation of solar light absorption within the snowpack (Libois et al. ,2013) and of the spectral partitioning of the direct and diffuse atmospheric irradiance and a prognostic snow impurity content. The added value of these refined representation of processes is evaluated with respect to field measurements of snow spectral reflectance and snow water equivalent. Simulations were performed at Col de Porte site (Chartreuse, France, 1325 m a.s.l.) using in situ meteorological forcings during winter 2013-2014 and aerosols deposition fluxes from MOCAGE chemistry transport atmospheric model. A major Saharian dust deposition event occurred in February 2014. Using simulations and measurements, we investigate in particular the impact of this event on the physical characteristics of the snowpack with a special focus on metamorphism and on the timing of melt.

  14. Point-focus spectral splitting solar concentrator for multiple cells concentrating photovoltaic system

    NASA Astrophysics Data System (ADS)

    Maragliano, Carlo; Chiesa, Matteo; Stefancich, Marco

    2015-10-01

    In this paper we present and experimentally validate a low-cost design of a spectral splitting concentrator for the efficient conversion of solar energy. The optical device consists of a dispersive prismatic lens made of polycarbonate designed to simultaneously concentrate solar light and split it into its spectral components. With respect to our previous implementation, this device concentrates light along two axes and generates a light pattern compatible with the dimensions of a set of concentrating photovoltaic cells, while providing a higher concentration ratio. The mathematical framework and the constructive approach used for the design are presented and the device performance is simulated using ray-tracing software. We obtain spectral separation in the visible range within a 3 × 1 cm2 area and a maximum concentration of 210× for a single wavelength. The device is fabricated by injection molding and its performance is experimentally investigated. We measure an optical transmissivity above 90% in the range 400-800 nm and we observe a spectral distribution in good accordance with simulations. Our results demonstrate the feasibility of the device for cost effective high efficiency concentrated photovoltaic systems.

  15. HARD X-RAY IMAGING OF INDIVIDUAL SPECTRAL COMPONENTS IN SOLAR FLARES

    SciTech Connect

    Caspi, Amir; Shih, Albert Y.; McTiernan, James M.; Krucker, Säm

    2015-09-20

    We present a new analytical technique, combining Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) high-resolution imaging and spectroscopic observations, to visualize solar flare emission as a function of spectral component (e.g., isothermal temperature) rather than energy. This computationally inexpensive technique is applicable to all spatially invariant spectral forms and is useful for visualizing spectroscopically determined individual sources and placing them in context, e.g., comparing multiple isothermal sources with nonthermal emission locations. For example, while extreme ultraviolet images can usually be closely identified with narrow temperature ranges, due to the emission being primarily from spectral lines of specific ion species, X-ray images are dominated by continuum emission and therefore have a broad temperature response, making it difficult to identify sources of specific temperatures regardless of the energy band of the image. We combine RHESSI calibrated X-ray visibilities with spatially integrated spectral models including multiple isothermal components to effectively isolate the individual thermal sources from the combined emission and image them separately. We apply this technique to the 2002 July 23 X4.8 event studied in prior works, and image for the first time the super-hot and cooler thermal sources independently. The super-hot source is farther from the footpoints and more elongated throughout the impulsive phase, consistent with an in situ heating mechanism for the super-hot plasma.

  16. Making of a solar spectral irradiance dataset I: observations, uncertainties, and methods

    NASA Astrophysics Data System (ADS)

    Schöll, Micha; Dudok de Wit, Thierry; Kretzschmar, Matthieu; Haberreiter, Margit

    2016-03-01

    Context. Changes in the spectral solar irradiance (SSI) are a key driver of the variability of the Earth's environment, strongly affecting the upper atmosphere, but also impacting climate. However, its measurements have been sparse and of different quality. The "First European Comprehensive Solar Irradiance Data Exploitation project" (SOLID) aims at merging the complete set of European irradiance data, complemented by archive data that include data from non-European missions. Aims: As part of SOLID, we present all available space-based SSI measurements, reference spectra, and relevant proxies in a unified format with regular temporal re-gridding, interpolation, gap-filling as well as associated uncertainty estimations. Methods: We apply a coherent methodology to all available SSI datasets. Our pipeline approach consists of the pre-processing of the data, the interpolation of missing data by utilizing the spectral coherency of SSI, the temporal re-gridding of the data, an instrumental outlier detection routine, and a proxy-based interpolation for missing and flagged values. In particular, to detect instrumental outliers, we combine an autoregressive model with proxy data. We independently estimate the precision and stability of each individual dataset and flag all changes due to processing in an accompanying quality mask. Results: We present a unified database of solar activity records with accompanying meta-data and uncertainties. Conclusions: This dataset can be used for further investigations of the long-term trend of solar activity and the construction of a homogeneous SSI record.

  17. Modeling the Climate Responses to Spectral Solar Variability on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Cahalan, Robert; Wen, Guoyong; Pilewskie, Peter; Harder, Jerald

    We apply two scenarios of external forcing, namely the SIM-based out-of-phase variations and the proxy-based in-phase variations, as input to a time-dependent radiative-convective model (RCM), and also to the GISS modelE GCM, to compute climate responses to solar variation on decadal time scale. We find that the maximum temperature response occurs in the upper stratosphere, while temperature response decreases downward to the surface for both scenarios, and both models. The upper stratospheric temperature peak-to-peak responses to out-of-phase solar forcing are 0.6 K in RCM and 0.9 K over the tropical region in GCM simulations, a factor of 5 times as large as responses to in-phase solar forcing. Stratospheric responses are in-phase with TSI (Total Solar Irradiance) variations. The modeled upper stratospheric temperature responses to the SORCE SIM observed SSI (Spectral Solar Irradiance) forcing are similar to the HALOE (Halogen Occultation Experiment) observed 11-year temperature variations. Surface responses to the two SSI scenarios are small for both RCM and GCM studies, as compared to the stratospheric responses. Though solar irradiance variations on centennial time scale are not well known, the two sce-narios of reconstructed TSI time series (i.e., the one based on 11-year cycle with background [Lean 2000] and the other one from flux transport that has much less background component [Wang, Lean, and Sheeley, 2005]) provide potential range of variations of TSI on centennial time scale. We apply phase relations among different spectral irradiance bands both from SIM observation and proxy reconstructions to the two scenarios of historical TSI to derive the as-sociated historical SSI. The historical SSI is used to drive the RCM. The updated atmosphere and ocean mixed coupled RCM including diffusion to deep-ocean will provide the first order estimate of temperature response to SSI variation on centennial time scales. We anticipate the stratosphere, troposphere, and

  18. 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.

  19. Spectrally-resolved Soft X-ray Observations and the Temperature Structure of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Warren, Harry; McTiernan, James; Woods, Thomas N.

    2015-04-01

    Solar X-ray observations provide important diagnostics of plasma heating and particle acceleration, during solar flares and quiescent periods. How the corona is heated to its ~1-3 MK nominal temperature remains one of the fundamental unanswered questions of solar physics; heating of plasma to tens of MK during solar flares -- particularly to the hottest observed temperatures of up to ~50 MK -- is also still poorly understood. Soft X-ray emission (~0.1-10 keV; or ~0.1-10 nm) is particularly sensitive to hot coronal plasma and serves as a probe of the thermal processes driving coronal plasma heating. Spectrally- and temporally-resolved measurements are crucial for understanding these energetic processes, but there have historically been very few such observations. We present new solar soft X-ray spectra from the Amptek X123-SDD, measuring quiescent solar X-ray emission from ~0.5 to ~30 keV with ~0.15 keV FWHM resolution from two SDO/EVE calibration sounding rocket underflights in 2012 and 2013. Combined with observations from RHESSI, GOES/XRS, SDO/EVE, and SDO/AIA, the temperature distribution derived from these data suggest significant hot (5-10 MK) emission from active regions, and the 2013 spectra suggest a low-FIP enhancement of only ~1.6 relative to the photosphere, 40% of the usually-observed value from quiescent coronal plasma. We explore the implications of these findings on coronal heating. We discuss future missions for spectrally-resolved soft X-ray observations using the X123-SDD, including the upcoming MinXSS 3U CubeSat using the X123-SDD and scheduled for deployment in mid-2015, and the CubIXSS 6U CubeSat mission concept.

  20. Spectral Analysis on Solar Flares with an Emission > 300 keV

    NASA Astrophysics Data System (ADS)

    Vargas, R.; Connaughton, V.

    2013-12-01

    The continuum gamma-ray emission from solar flares is caused when a population of electrons is accelerated to relativistic speeds and interacts with the solar plasma. However, it has been theorized that the gamma-ray emission from some brighter flares comes from two populations of electrons. Using the Gamma-Ray Burst Monitor (GBM), we studied the gamma-ray emission spectra of solar flares and paid special attention to the solar flares that showed emission above 300 keV. We found that the emission above 300 keV was better fit with a broken power-law than a single power-law, evidence that the gamma-ray emission from certain solar flares involved two populations of electrons. Specifically, our best model involved a broken power law that had a steeper slope before the break in energy than after. We studied the spectral parameters as a function of time during the period of the high-energy emission. We also found that solar flares with emission above 300 keV form a small subset (~4%) of flares that trigger GBM above 20 keV. One of the flares with an emission greater than 300 keV was fitted with a Broken Power Law model. Only data from the BGO detector was used in making the plots. Various parameters of the fit have been plotted vs. time with the top two graphs representing the light curves of the flare from different detectors (BGO-0 and NaI-4). A spectral fit for bn100612038 for the time interval of [45s-50s] using only the BGO (0) detector file. Data from this fit was used in creating the other plots.

  1. The Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors

    NASA Technical Reports Server (NTRS)

    Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B. C., Jr.; Allen, Max J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C.

    1992-01-01

    We have developed seven compact soft X-ray/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

  2. Analysis of Solar Spectral Irradiance Measurements from the SBUV/2-Series and the SSBUV Instruments

    NASA Technical Reports Server (NTRS)

    Cebula, Richard P.; DeLand, Matthew T.; Hilsenrath, Ernest

    1997-01-01

    During this period of performance, 1 March 1997 - 31 August 1997, the NOAA-11 SBUV/2 solar spectral irradiance data set was validated using both internal and external assessments. Initial quality checking revealed minor problems with the data (e.g. residual goniometric errors, that were manifest as differences between the two scans acquired each day). The sources of these errors were determined and the errors were corrected. Time series were constructed for selected wavelengths and the solar irradiance changes measured by the instrument were compared to a Mg II proxy-based model of short- and long-term solar irradiance variations. This analysis suggested that errors due to residual, uncorrected long-term instrument drift have been reduced to less than 1-2% over the entire 5.5 year NOAA-11 data record. Detailed statistical analysis was performed. This analysis, which will be documented in a manuscript now in preparation, conclusively demonstrates the evolution of solar rotation periodicity and strength during solar cycle 22.

  3. The applied research and solar simulation spectral design based on pulse xenon lamp with coating film

    NASA Astrophysics Data System (ADS)

    Chen, Wenzhi; Cheng, Qijin; Zhang, Fengyan

    2014-09-01

    In the paper the spectrum of realistic sunlight and pulse xenon lamp were compared to each other, the result shows that the infrared part of luminescence spectrum of xenon lamp without coating film occupies the total spectrum's 57.4%, but the infrared part of the standard solar spectrum only reaches to 28.3%. The transmittance curve of pulse xenon lamp is got by fitting. Using appropriate method and coating film parameter, the film is done to pulse xenon lamp, and the negative film coefficient transmittance is 16% is got at 935nm central wavelength. At the range of 400-760nm wavelength the average transmittance is more than 86%, and the average transmittance is more than 96% at the range of 400-760nm wavelength. A portion of infrared light can be filtered after coating film. By the spectral testing of two coating film xenon lamp, it can be found that the spectral matching rate is from 0.792 to 1.176 and it is satisfied to A grade standard request. By using A and C grade pulse xenon lamp electric performance of 40.5W thin film cell is tested and the power value by C grade simulative light source is lower than real power for 11.2W. The result indicates the spectral matching rate of solar simulator is very important for cell electric performance.

  4. Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona

    NASA Astrophysics Data System (ADS)

    Ruan, Wenzhi; He, Jiansen; Zhang, Lei; Vocks, Christian; Marsch, Eckart; Tu, Chuanyi; Peter, Hardi; Wang, Linghua

    2016-03-01

    We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data of the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the "wave + beam flow" kinetic model may be a viable interpretation for the PIDs observed in the solar corona.

  5. Spectral irradiance variations: comparison between observations and the SATIRE model on solar rotation time scales

    NASA Astrophysics Data System (ADS)

    Unruh, Y. C.; Krivova, N. A.; Solanki, S. K.; Harder, J. W.; Kopp, G.

    2008-07-01

    Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance observations taken with SORCE/SIM, SoHO/VIRGO, and UARS/SUSIM. The calculations assume LTE and are based on the SATIRE (Spectral And Total Irradiance REconstruction) model. We analyse the variability as a function of wavelength and present time series in a number of selected wavelength regions covering the UV to the NIR. We also show the facular and spot contributions to the total calculated variability. Results: In most wavelength regions, the variability agrees well between all sets of observations and the model calculations. The model does particularly well between 400 and 1300 nm, but fails below 220 nm, as well as for some of the strong NUV lines. Our calculations clearly show the shift from faculae-dominated variability in the NUV to spot-dominated variability above approximately 400 nm. We also discuss some of the remaining problems, such as the low sensitivity of SUSIM and SORCE for wavelengths between approximately 310 and 350 nm, where currently the model calculations still provide the best estimates of solar variability.

  6. 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.

  7. An Evaluation of Total Solar Reflectance and Spectral Band Ratioing Techniques for Estimating Soil Water Content

    NASA Technical Reports Server (NTRS)

    Reginato, R. J.; Vedder, J. F.; Idso, S. B.; Jackson, R. D.; Blanchard, M. B.; Goettelman, R.

    1977-01-01

    For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300-m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil-type discrimination based on identification of type-specific spectral signatures. Therefore remote sensing, conducted in the 0.4- to 1.0-micron wavelength region of the solar spectrum, would seem to be much More suited to identifying crop and soil types than to estimating of soil water content.

  8. Project STOP (Spectral Thermal Optimization Program)

    NASA Technical Reports Server (NTRS)

    Goldhammer, L. J.; Opjorden, R. W.; Goodelle, G. S.; Powe, J. S.

    1977-01-01

    The spectral thermal optimization of solar cell configurations for various solar panel applications is considered. The method of optimization depends upon varying the solar cell configuration's optical characteristics to minimize panel temperatures, maximize power output and decrease the power delta from beginning of life to end of life. Four areas of primary investigation are: (1) testing and evaluation of ultraviolet resistant coverslide adhesives, primarily FEP as an adhesive; (2) examination of solar cell absolute spectral response and corresponding cell manufacturing processes that affect it; (3) experimental work with solar cell manufacturing processes that vary cell reflectance (solar absorptance); and (4) experimental and theoretical studies with various coverslide filter designs, mainly a red rejection filter. The Hughes' solar array prediction program has been modified to aid in evaluating the effect of each of the above four areas on the output of a solar panel in orbit.

  9. WHAT DO SPECTRAL LINE PROFILE ASYMMETRIES TELL US ABOUT THE SOLAR ATMOSPHERE?

    SciTech Connect

    MartInez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo; McIntosh, Scott W.

    2011-05-10

    Recently, analysis of solar spectra obtained with the EUV Imaging Spectrograph (EIS) onboard the Hinode satellite has revealed the ubiquitous presence of asymmetries in transition region (TR) and coronal spectral line profiles. These asymmetries have been observed especially at the footpoints of coronal loops and have been associated with strong upflows that may play a significant role in providing the corona with hot plasma. Here, we perform a detailed study of the various processes that can lead to spectral line asymmetries, using both simple forward models and state-of-the-art three-dimensional radiative MHD simulations of the solar atmosphere using the Bifrost code. We describe a novel technique to determine the presence and properties of faint secondary components in the wings of spectral line profiles. This method is based on least-squares fitting of observed so-called R(ed)B(lue) asymmetry profiles with pre-calculated RB asymmetry profiles for a wide variety of secondary component properties. We illustrate how this method could be used to perform reliable double Gaussian fits that are not over- or under-constrained. We also find that spectral line asymmetries appear in TR and coronal lines that are synthesized from our three-dimensional MHD simulations. Our models show that the spectral asymmetries are a sensitive measure of the velocity gradient with height in the TR of coronal loops. The modeled TR shows a large gradient of velocity that increases with height: this occurs as a consequence of ubiquitous, episodic heating at low heights in the model atmosphere. We show that the contribution function of spectral lines as a function of temperature is critical for sensitivity to velocity gradients and thus line asymmetries: lines that are formed over a temperature range that includes most of the TR are the most sensitive. As a result, lines from lithium-like ions (e.g., O VI) are found to be the most sensitive to line asymmetries. We compare the simulated line

  10. Geoeffectiveness of solar flares in magnetic crochet (sfe) production: I—Dependence on their spectral nature and position on the solar disk

    NASA Astrophysics Data System (ADS)

    Curto, Juan José; Gaya-Piqué, Luis R.

    2009-12-01

    The influence of the spectral nature and position on the solar disk of solar flares related to the production of magnetic effects on earth (from now on, sfe) over a more than 30-year period has been studied. Regarding the spectral issue, we found that the probability of a flare to produce sfe depends on the spectral band in which we observe it, being higher when the flare is important both in H[alpha] and X-ray emissions. On the other hand, H[alpha] and X-ray emissions have been considered in many different divisions of the solar surface and their effectiveness on sfe production have been compared. We found that there is not any privileged region on the solar disk for sfe production. These results end with the controversy generated by distinct conclusions obtained in classical studies on the subject.

  11. Phase Coupling Between Spectral Components of Collapsing Langmuir Solitons in Solar Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2012-01-01

    We present the high time resolution observations of one of the Langmuir wave packets obtained in the source region of a solar type III radio burst. This wave packet satisfies the threshold condition of the supersonic modulational instability, as well as the criterion of a collapsing Langmuir soliton, i.e., the spatial scale derived from its peak intensity is less than that derived from its short time scale. The spectrum of t his wave packet contains an intense spectral peak at local electron plasma frequency, f(sub pe) and relatively weaker peaks at 2f(sub pe) and 3f(sub pe). We apply the wavelet based bispectral analysis technique on this wave packet and compute the bicoherence between its spectral components. It is found that the bicoherence exhibits two peaks at (approximately f(sub pe), approximately f(sub pe)) and (approximately f(sub pe) approximately 2f(sub pe)), which strongly suggest that the spectral peak at 2f(sub pe) probably corresponds to the second harmonic radio emission, generated as a result of the merging of antiparallel propagating Langmuir waves trapped in the collapsing Langmuir soliton, and, the spectral peak at 3f(sub pe) probably corresponds to the third harmonic radio emission, generated as a result of merging of a trapped Langmuir wave and a second harmonic electromagnetic wave.

  12. TEMPORAL SPECTRAL SHIFT AND POLARIZATION OF A BAND-SPLITTING SOLAR TYPE II RADIO BURST

    SciTech Connect

    Du, Guohui; Chen, Yao; Lv, Maoshui; Kong, Xiangliang; Feng, Shiwei; Guo, Fan; Li, Gang

    2014-10-01

    In many type II solar radio bursts, the fundamental and/or the harmonic branches of the bursts can split into two almost parallel bands with similar spectral shapes and frequency drifts. However, the mechanisms accounting for this intriguing phenomenon remain elusive. In this study, we report a special band-splitting type II event in which spectral features appear systematically earlier on the upper band (with higher frequencies) than on the lower band (with lower frequencies) by several seconds. Furthermore, the emissions carried by the splitting band are moderately polarized with the left-hand polarized signals stronger than the right-hand ones. The polarization degree varies in a range of –0.3 to –0.6. These novel observational findings provide important constraints on the underlying physical mechanisms of band-splitting of type II radio bursts.

  13. Airborne Sunphotometer and Solar Spectral Flux Radiometer Measurements During INTEX/ITCT 2004

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Pilewski, P.; Redemann, J.; Schmid, B.; Kahn, R.; Livingston, J.; Chu, A.; Eilers, J.; Pommier, J.; Howard, S.

    2005-01-01

    During the period 12 July - 8 August 2004, the NASA Ames 14-channel Airborne Tracking Sunphotometer (MTS-14) and Solar Spectral Flux Radiometer (SSFR) were operated aboard a Jetstream 31 (J31) aircraft and acquired measurements during nineteen science flights (approx. 53 flight hours) over the Gulf of Maine in support of the INTEX-NA (INtercontinental chemical Transport Experiment-North America) and ITCT (Intercontinental Transport and Chemical Transformation of anthropogenic pollution) field studies. In this paper, we will present results from analyses of those data sets. AATS-14 measures the direct solar beam transmission at fourteen discrete wavelengths (354-2138 nm), and provides instantaneous measurements of aerosol optical depth (AOD) spectra and water vapor column content, in addition to vertical profiles of aerosol extinction and water vapor density during suitable aircraft ascents and descents. SSFR consists of separate nadir and zenith viewing hemispheric FOV sensors that yield measurements of up- and downwelling solar irradiance at a spectral resolution of approx. 8-12 nm over the wavelength range 300-1700 nm. The objectives of the J31-based measurements during INTEX/ITCT were to provide AOD data for the evaluation of MODIS (MODerate-resolution Imaging Spectroradiometer) and MISR (Multi-angle Imaging Spectro-Radiometer) AOD retrievals, quantify sea surface spectral albedo (which can contribute the largest uncertainty to satellite aerosol retrievals for low aerosol loading), test closure (consistency) among suborbital results, test chemical-transport models using AOD profiles, and assess regional radiative forcing by combining satellite and suborbital results. Specific J31 flight patterns were designed to achieve these objectives, and they included a mixture of vertical profiles (spiral and ramped ascents and descents) and constant altitude horizontal transects at a variety of altitudes. Additional information is included in the original extended abstract.

  14. Power spectral density and scaling exponent of high frequency global solar radiation sequences

    NASA Astrophysics Data System (ADS)

    Calif, Rudy; Schmitt, François G.; Huang, Yongxiang

    2013-04-01

    The part of the solar power production from photovlotaïcs systems is constantly increasing in the electric grids. Solar energy converter devices such as photovoltaic cells are very sensitive to instantaneous solar radiation fluctuations. Thus rapid variation of solar radiation due to changes in the local meteorological condition can induce large amplitude fluctuations of the produced electrical power and reduce the overall efficiency of the system. When large amount of photovoltaic electricity is send into a weak or small electricity network such as island network, the electric grid security can be in jeopardy due to these power fluctuations. The integration of this energy in the electrical network remains a major challenge, due to the high variability of solar radiation in time and space. To palliate these difficulties, it is essential to identify the characteristic of these fluctuations in order to anticipate the eventuality of power shortage or power surge. The objective of this study is to present an approach based on Empirical Mode Decomposition (EMD) and Hilbert-Huang Transform (HHT) to highlight the scaling properties of global solar irradiance data G(t). The scale of invariance is detected on this dataset using the Empirical Mode Decomposition in association with arbitrary-order Hilbert spectral analysis, a generalization of (HHT) or Hilbert Spectral Analysis (HSA). The first step is the EMD, consists in decomposing the normalized global solar radiation data G'(t) into several Intrinsic Mode Functions (IMF) Ci(t) without giving an a priori basis. Consequently, the normalized original solar radiation sequence G'(t) can be written as a sum of Ci(t) with a residual rn. From all IMF modes, a joint PDF P(f,A) of locally and instantaneous frequency f and amplitude A, is estimated. To characterize the scaling behavior in amplitude-frequency space, an arbitrary-order Hilbert marginal spectrum is defined to: Iq(f) = 0 P (f,A)A dA (1) with q × 0 In case of scale

  15. EUV/FUV response characteristics of photographic films for the Multi-Spectral Solar Telescope Array

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest, Craig E.; Allen, Maxwell J.; Lindblom, Joakim F.

    1991-01-01

    The photographic film employed by NASA's Multi-Spectral Solar Telescope Array must have high-to-ultrahigh resolution; since the spacecraft bearing the telescope must be evacuated to prevent the failure of delicate EUV and soft X-ray filters due to acoustic vibration during launch, the films must also have very low outgassing rates. An account is presently given of the properties of important new emulsions selected for flight, together with response-characteristics data for the experimental XUV 100 film and an uncoated Spectroscopic 649 emulsion.

  16. Spectral reflectance properties of electroplated and converted zinc for use as a solar selective coating

    NASA Technical Reports Server (NTRS)

    Mcdonald, G. E.; Curtis, H. B.; Gianelos, L.

    1975-01-01

    The spectral reflectance properties of electroplated and chemically converted zinc were measured for both chromate and chloride conversion coatings. The reflectance properties were measured for various times of conversion and for conversion at various chromate concentrations. The values of absorptance, integrated over the solar spectrum, and of infrared emittance, integrated over black body radiation at 250 F were then calculated from the measured reflectance values. The interdependent variations of absorptance and infrared emittance were plotted. The results indicate that the optimum combination of the highest absorptance in the solar spectrum and the lowest emittance in the infrared of the converted electroplated zinc is produced by chromate conversion at 1/2 concentration of the standard NEOSTAR chromate black solution for 0.50 minute or by chloride conversion for 0.50 minute.

  17. Spectral anisotropy of solar wind turbulence in the inertial range and dissipation range

    SciTech Connect

    Podesta, J. J.

    2010-03-25

    Wavelet analysis is a tool that can simultaneously analyze spacecraft data in both time and frequency. This enables the magnetic energy spectrum (trace spectrum) to be measured for different angles between the local mean magnetic field B{sub 0} and the direction of the mean flow within a single data set. Examples obtained around solar minimum using Ulysses data at high latitudes and Stereo data for high-speed streams in the ecliptic plane show that the spectral exponent in the inertial range varies nearly monotonically from approximately 1.6 when B{sub 0} is perpendicular to the flow to 2.0 when B{sub 0} is parallel to the flow, roughly consistent with anisotropic theories of incompressible MHD turbulence. This and other new information about the 3D wavector spectrum of solar wind fluctuations in the inertial range and the dissipation range are briefly discussed.

  18. Spectral Atlas of X-ray Lines Emitted During Solar Flares Based on CHIANTI

    NASA Technical Reports Server (NTRS)

    Landi, E.; Phillips, K. J. H.

    2005-01-01

    A spectral atlas of X-ray lines in the wavelength range 7.47-18.97 Angstroms is presented, based on high-resolution spectra obtained during two M-class solar flares (on 1980 August 25 and 1985 July 2) with the Flat Crystal Spectrometer on board the Solar Maximum Mission. The physical properties of the flaring plasmas are derived as a function of time using strong, isolated lines. From these properties predicted spectra using the CHIANTI database have been obtained which were then compared with wavelengths and fluxes of lines in the observed spectra to establish line identifications. identifications for nearly all the observed lines in the resulting atlas are given, with some significant corrections to previous analysis of these flare spectra.

  19. Modeling the Temperature Responses to Spectral Solar Variability on Decadal and Centennial Time Scales

    NASA Astrophysics Data System (ADS)

    Cahalan, R. F.; Wen, G.; Pilewskie, P.; Harder, J. W.

    2010-12-01

    Atmospheric temperature responses to decadal solar variations are computed for two scenarios of solar spectral irradiance (SSI), SIM-based out-of-phase and proxy-based in-phase variations, using a time-dependent radiative-convective model (RCM), and also GISS modelE (GCM.) For both scenarios and both models, maximum responses occur in upper stratosphere, decreasing downward to the surface. Upper stratospheric temperature peak-to-peak responses to out-of-phase forcing are ~0.6 K in RCM and ~0.9 K over tropics in GCM, ~5x as large as responses to in-phase forcing. Stratospheric responses are in-phase with TSI (Total Solar Irradiance). Modeled upper stratospheric temperature responses to SIM-based forcing are similar to 11-year temperature variations observed with HALOE (Halogen Occultation Experiment). For both RCM and GCM, surface responses to the two scenarios are significantly smaller than stratospheric responses. On centennial timescales, SSI variations are poorly known. However, two scenarios of reconstructed TSI, one based on 11-year cycle with background [Lean 2000] and the other on flux transport with much less background [Wang, Lean, and Sheeley, 2005], provide a potential range of TSI variations. We apply phase relations among different SSI bands both from SIM observations and proxy reconstructions to the two scenarios of historical TSI to derive associated historical SSI, which then drives the RCM. The updated atmosphere and ocean mixed coupled RCM including diffusion to deep-ocean provide a first order estimate of temperature responses to SSI variations on centennial time scales. We discuss potential mechanisms for atmosphere-ocean and stratosphere-troposphere couplings responsible for the climate responses to spectral solar variations.

  20. Spectrally-selective all-inorganic scattering luminophores for solar energy-harvesting clear glass windows

    NASA Astrophysics Data System (ADS)

    Alghamedi, Ramzy; Vasiliev, Mikhail; Nur-E-Alam, Mohammad; Alameh, Kamal

    2014-10-01

    All-inorganic visibly-transparent energy-harvesting clear laminated glass windows are the most practical solution to boosting building-integrated photovoltaics (BIPV) energy outputs significantly while reducing cooling- and heating-related energy consumption in buildings. By incorporating luminophore materials into lamination interlayers and using spectrally-selective thin-film coatings in conjunction with CuInSe2 solar cells, most of the visible solar radiation can be transmitted through the glass window with minimum attenuation while ultraviolet (UV) radiation is down-converted and routed together with a significant part of infrared radiation to the edges for collection by solar cells. Experimental results demonstrate a 10 cm × 10 cm vertically-placed energy-harvesting clear glass panel of transparency exceeding 60%, invisible solar energy attenuation greater than 90% and electrical power output near 30 Wp/m2 mainly generated by infrared (IR) and UV radiations. These results open the way for the realization of large-area visibly-transparent energy-harvesting clear glass windows for BIPV systems.

  1. The SPICE Spectral Imager on Solar Orbiter: Linking the Sun to the Heliosphere

    NASA Astrophysics Data System (ADS)

    Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Davila, Joseph; Giunta, Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo

    2016-07-01

    The SPICE (Spectral Imaging of the Coronal Environment) instrument is one of the key remote sensing instruments onboard the upcoming Solar Orbiter Mission. SPICE has been designed to contribute to the science goals of the mission by investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. In particular, SPICE will provide quantitative information on the physical state and composition of the solar atmosphere plasma. For example, SPICE will access relative abundances of ions to study the origin and the spatial/temporal variations of the 'First Ionization Potential effect', which are key signatures to trace the solar wind and plasma ejections paths within the heliosphere. Here we will present the instrument and its performance capability to attain the scientific requirements. We will also discuss how different observation modes can be chosen to obtain the best science results during the different orbits of the mission. To maximize the scientific return of the instrument, the SPICE team is working to optimize the instrument operations, and to facilitate the data access and their exploitation.

  2. Spectrally-selective all-inorganic scattering luminophores for solar energy-harvesting clear glass windows.

    PubMed

    Alghamedi, Ramzy; Vasiliev, Mikhail; Nur-E-Alam, Mohammad; Alameh, Kamal

    2014-10-16

    All-inorganic visibly-transparent energy-harvesting clear laminated glass windows are the most practical solution to boosting building-integrated photovoltaics (BIPV) energy outputs significantly while reducing cooling- and heating-related energy consumption in buildings. By incorporating luminophore materials into lamination interlayers and using spectrally-selective thin-film coatings in conjunction with CuInSe2 solar cells, most of the visible solar radiation can be transmitted through the glass window with minimum attenuation while ultraviolet (UV) radiation is down-converted and routed together with a significant part of infrared radiation to the edges for collection by solar cells. Experimental results demonstrate a 10 cm × 10 cm vertically-placed energy-harvesting clear glass panel of transparency exceeding 60%, invisible solar energy attenuation greater than 90% and electrical power output near 30 Wp/m(2) mainly generated by infrared (IR) and UV radiations. These results open the way for the realization of large-area visibly-transparent energy-harvesting clear glass windows for BIPV systems.

  3. Spectrally-selective all-inorganic scattering luminophores for solar energy-harvesting clear glass windows.

    PubMed

    Alghamedi, Ramzy; Vasiliev, Mikhail; Nur-E-Alam, Mohammad; Alameh, Kamal

    2014-01-01

    All-inorganic visibly-transparent energy-harvesting clear laminated glass windows are the most practical solution to boosting building-integrated photovoltaics (BIPV) energy outputs significantly while reducing cooling- and heating-related energy consumption in buildings. By incorporating luminophore materials into lamination interlayers and using spectrally-selective thin-film coatings in conjunction with CuInSe2 solar cells, most of the visible solar radiation can be transmitted through the glass window with minimum attenuation while ultraviolet (UV) radiation is down-converted and routed together with a significant part of infrared radiation to the edges for collection by solar cells. Experimental results demonstrate a 10 cm × 10 cm vertically-placed energy-harvesting clear glass panel of transparency exceeding 60%, invisible solar energy attenuation greater than 90% and electrical power output near 30 Wp/m(2) mainly generated by infrared (IR) and UV radiations. These results open the way for the realization of large-area visibly-transparent energy-harvesting clear glass windows for BIPV systems. PMID:25321890

  4. Fabrication of spectrally selective solar surfaces by the thermal treatment of austenitic stainless steel aisi 321

    SciTech Connect

    Sharma, V.C.

    1981-05-19

    The spectrally selective solar surfaces have been produced after heating the austenitic stainless steel aisi 321 at a firing temperature of 843* K. And for firing times ranging from 10 to 20 minutes. The heating was carried out in a constant temperature oven under normal atmospheric conditions. The optimum values of solar absorptance alpha S and near-normal emittance epsilon S were found to be alpha S 0.92+0.02, epsilon S 0.22 + or - 0.02 respectively. The corresponding values for the unheated steel were 0.50 + or - 0.02 and 0.22 + or - 0.22. Severe temperature treatments like quenching in liquid nitrogen at 77* K. Produced no adverse visible affect on the quality of the selective surfaces. It shows that the thermal coatings so produced are very tough and durable. The value of solar absorptance and near-normal thermal emittance remained unchanged after quenching in liquod nitrogen. The thermal coatings so produced not only offer a technical advantage but also economic advantage over any of the existing techniques for the manufacture of stainless steel solar panels.

  5. 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.

  6. Spectral analysis of the solar wind turbulence in the vicinity of Venus

    NASA Astrophysics Data System (ADS)

    Teodorescu, Eliza; Echim, Marius; Munteanu, Costel; Voitcu, Gabriel; Zhang, Tielong; Barabash, Stanislav; Budnik, Elena; Fedorov, Andrei

    2014-05-01

    In this study we analyze magnetic field data provided by Venus Express (VEX) between 2007 and 2008. During each of the probe's eccentric polar orbit around Venus, VEX performs plasma and magnetic field measurements in the environment around the planet both in Venus induced magnetosphere and in the solar wind at several tens of thousands of kilometers away from the magnetosphere. This latter data set has a unique scientific value as it provides observations of magnetic turbulence in the solar wind around 0.72 AU, in the vicinity of Venus. We discuss a semi-automated method to select solar wind magnetic field data at 1 Hz from Venus Express Magnetometer (MAG) data by using plasma data from the Analyser of Space Plasma and Energetic Atoms (ASPERA). The time intervals when VEX is in the solar wind are automatically determined for 2007 and 2008. We apply a Fourier transform on the selected data and calculate the power spectral densities (PSD) of the turbulent magnetic field through Welch's algorithm. We compute the PSD of the three components of the magnetic field for the time intervals when both MAG and ASPERA were operating in the solar wind, for each VEX orbit between 1st of January 2007 and 31st of December 2008. The data base includes a number of 374 individual spectra. We discuss the spectral properties of turbulence and illustrate similarities between fast and slow wind during the minimum phase of the solar cycle for each of VEX's orbit which satisfies the selection criteria for a period of two years. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418. Data analysis was done with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (IRAP, Université Paul Sabatier, Toulouse) supported by CNRS and CNES.

  7. International Photolysis Frequency Measurement and Model Intercomparison (IPMMI): Spectral actinic solar flux measurements and modeling

    NASA Astrophysics Data System (ADS)

    Bais, A. F.; Madronich, S.; Crawford, J.; Hall, S. R.; Mayer, B.; van Weele, M.; Lenoble, J.; Calvert, J. G.; Cantrell, C. A.; Shetter, R. E.; Hofzumahaus, A.; Koepke, P.; Monks, P. S.; Frost, G.; McKenzie, R.; Krotkov, N.; Kylling, A.; Swartz, W. H.; Lloyd, S.; Pfister, G.; Martin, T. J.; Roeth, E.-P.; Griffioen, E.; Ruggaber, A.; Krol, M.; Kraus, A.; Edwards, G. D.; Mueller, M.; Lefer, B. L.; Johnston, P.; Schwander, H.; Flittner, D.; Gardiner, B. G.; Barrick, J.; Schmitt, R.

    2003-08-01

    The International Photolysis Frequency Measurement and Model Intercomparison (IPMMI) took place in Boulder, Colorado, from 15 to 19 June 1998, aiming to investigate the level of accuracy of photolysis frequency and spectral downwelling actinic flux measurements and to explore the ability of radiative transfer models to reproduce the measurements. During this period, 2 days were selected to compare model calculations with measurements, one cloud-free and one cloudy. A series of ancillary measurements were also performed and provided parameters required as input to the models. Both measurements and modeling were blind, in the sense that no exchanges of data or calculations were allowed among the participants, and the results were objectively analyzed and compared by two independent referees. The objective of this paper is, first, to present the results of comparisons made between measured and modeled downwelling actinic flux and irradiance spectra and, second, to investigate the reasons for which some of the models or measurements deviate from the others. For clear skies the relative agreement between the 16 models depends strongly on solar zenith angle (SZA) and wavelength as well as on the input parameters used, like the extraterrestrial (ET) solar flux and the absorption cross sections. The majority of the models (11) agreed to within about ±6% for solar zenith angles smaller than ˜60°. The agreement among the measured spectra depends on the optical characteristics of the instruments (e.g., slit function, stray light rejection, and sensitivity). After transforming the measurements to a common spectral resolution, two of the three participating spectroradiometers agree to within ˜10% for wavelengths longer than 310 nm and at all solar zenith angles, while their differences increase when moving to shorter wavelengths. Most models agree well with the measurements (both downwelling actinic flux and global irradiance), especially at local noon, where the agreement

  8. A simple framework for modelling the photochemical response to solar spectral irradiance variability in the stratosphere

    NASA Astrophysics Data System (ADS)

    Muncaster, R.; Bourqui, M. S.; Chabrillat, S.; Viscardy, S.; Melo, S. M. L.; Charbonneau, P.

    2012-08-01

    The stratosphere is thought to play a central role in the atmospheric response to solar irradiance variability. Recent observations suggest that the spectral solar irradiance (SSI) variability involves significant time-dependent spectral variations, with variable degrees of correlation between wavelengths, and new reconstructions are being developed. In this paper, we propose a simplified modelling framework to characterise the effect of short term SSI variability on stratospheric ozone. We focus on the pure photochemical effect, for it is the best constrained one. The photochemical effect is characterised using an ensemble simulation approach with multiple linear regression analysis. A photochemical column model is used with interactive photolysis for this purpose. Regression models and their coefficients provide a characterisation of the stratospheric ozone response to SSI variability and will allow future inter-comparisons between different SSI reconstructions. As a first step in this study, and to allow comparison with past studies, we take the representation of SSI variability from the Lean (1997) solar minimum and maximum spectra. First, solar maximum-minimum response is analysed for all chemical families and partitioning ratios, and is compared with past studies. The ozone response peaks at 0.18 ppmv (approximately 3%) at 37 km altitude. Second, ensemble simulations are regressed following two linear models. In the simplest case, an adjusted coefficient of determination R2 larger than 0.97 is found throughout the stratosphere using two predictors, namely the previous day's ozone perturbation and the current day's solar irradiance perturbation. A better accuracy (R2 larger than 0.9992) is achieved with an additional predictor, the previous day's solar irradiance perturbation. The regression models also provide simple parameterisations of the ozone

  9. A STATISTICAL STUDY OF THE SPECTRAL HARDENING OF CONTINUUM EMISSION IN SOLAR FLARES

    SciTech Connect

    Kong, X.; Chen, Y.; Li, G. E-mail: gang.li@uah.edu

    2013-09-10

    The observed hard X-ray and {gamma}-ray continuum in solar flares is interpreted as Bremsstrahlung emission of accelerated non-thermal electrons. It has been noted for a long time that in many flares the energy spectra show hardening at energies around or above 300 keV. In this paper, we first conduct a survey of spectral hardening events that were previously studied in the literature. We then perform a systematic examination of 185 flares from the Solar Maximum Mission. We identify 23 electron-dominated events whose energy spectra show clear double power laws. A statistical study of these events shows that the spectral index below the break ({gamma}{sub 1}) anti-correlates with the break energy ({epsilon}{sub b}). Furthermore, {gamma}{sub 1} also anti-correlates with Fr, the fraction of photons above the break compared to the total photons. A hardening spectrum, as well as the correlations between ({gamma}{sub 1}, {epsilon}{sub b}) and ({gamma}{sub 1}, Fr), provide stringent constraints on the underlying electron acceleration mechanism. Our results support a recent proposal that electrons are being accelerated diffusively at a flare termination shock with a width of the order of an ion inertial length scale.

  10. Solar spectral conversion for improving the photosynthetic activity in algae reactors.

    PubMed

    Wondraczek, Lothar; Batentschuk, Miroslaw; Schmidt, Markus A; Borchardt, Rudolf; Scheiner, Simon; Seemann, Benjamin; Schweizer, Peter; Brabec, Christoph J

    2013-01-01

    Sustainable biomass production is expected to be one of the major supporting pillars for future energy supply, as well as for renewable material provision. Algal beds represent an exciting resource for biomass/biofuel, fine chemicals and CO2 storage. Similar to other solar energy harvesting techniques, the efficiency of algal photosynthesis depends on the spectral overlap between solar irradiation and chloroplast absorption. Here we demonstrate that spectral conversion can be employed to significantly improve biomass growth and oxygen production rate in closed-cycle algae reactors. For this purpose, we adapt a photoluminescent phosphor of the type Ca0.59Sr0.40Eu0.01S, which enables efficient conversion of the green part of the incoming spectrum into red light to better match the Qy peak of chlorophyll b. Integration of a Ca0.59Sr0.40Eu0.01S backlight converter into a flat panel algae reactor filled with Haematococcus pluvialis as a model species results in significantly increased photosynthetic activity and algae reproduction rate.

  11. Solar spectral conversion for improving the photosynthetic activity in algae reactors

    NASA Astrophysics Data System (ADS)

    Wondraczek, Lothar; Batentschuk, Miroslaw; Schmidt, Markus A.; Borchardt, Rudolf; Scheiner, Simon; Seemann, Benjamin; Schweizer, Peter; Brabec, Christoph J.

    2013-06-01

    Sustainable biomass production is expected to be one of the major supporting pillars for future energy supply, as well as for renewable material provision. Algal beds represent an exciting resource for biomass/biofuel, fine chemicals and CO2 storage. Similar to other solar energy harvesting techniques, the efficiency of algal photosynthesis depends on the spectral overlap between solar irradiation and chloroplast absorption. Here we demonstrate that spectral conversion can be employed to significantly improve biomass growth and oxygen production rate in closed-cycle algae reactors. For this purpose, we adapt a photoluminescent phosphor of the type Ca0.59Sr0.40Eu0.01S, which enables efficient conversion of the green part of the incoming spectrum into red light to better match the Qy peak of chlorophyll b. Integration of a Ca0.59Sr0.40Eu0.01S backlight converter into a flat panel algae reactor filled with Haematococcus pluvialis as a model species results in significantly increased photosynthetic activity and algae reproduction rate.

  12. HARD X-RAY AND MICROWAVE EMISSIONS FROM SOLAR FLARES WITH HARD SPECTRAL INDICES

    SciTech Connect

    Kawate, T.; Nishizuka, N.; Oi, A.; Ohyama, M.; Nakajima, H.

    2012-03-10

    We analyze 10 flare events that radiate intense hard X-ray (HXR) emission with significant photons over 300 keV to verify that the electrons that have a common origin of acceleration mechanism and energy power-law distribution with solar flares emit HXRs and microwaves. Most of these events have the following characteristics. HXRs emanate from the footpoints of flare loops, while microwaves emanate from the tops of flare loops. The time profiles of the microwave emission show delays of peak with respect to those of the corresponding HXR emission. The spectral indices of microwave emissions show gradual hardening in all events, while the spectral indices of the corresponding HXR emissions are roughly constant in most of the events, though rather rapid hardening is simultaneously observed in some for both indices during the onset time and the peak time. These characteristics suggest that the microwave emission emanates from the trapped electrons. Then, taking into account the role of the trapping of electrons for the microwave emission, we compare the observed microwave spectra with the model spectra calculated by a gyrosynchrotron code. As a result, we successfully reproduce the eight microwave spectra. From this result, we conclude that the electrons that have a common acceleration and a common energy distribution with solar flares emit both HXR and microwave emissions in the eight events, though microwave emission is contributed to by electrons with much higher energy than HXR emission.

  13. Analysis of the Solar magnetograms evolution using a spectral gap of critical nets

    NASA Astrophysics Data System (ADS)

    Knyazeva, I. S.; Makarenko, N. G.; Makarenko, I.; Vdovina, A.; Urtiev, F. A.

    2016-08-01

    Analyzing the dynamics of the photospheric magnetic field of the Sun is one of the most important problems in Solar Physics. Different estimates of the complexity of magnetograms of the Sun Active Regions (AR) are used to predict the time and the strength of the solar flares, but the quality of the forecasts are still insufficient. A magnetogram is a highly variable discrete image with a very large number of local extrema. We use an idea of extraction of stable critical points within a framework of the scale-space theory. Two sequential convolutions of the image with the same Gaussian kernel and calculating the difference between the produced images allow to get a stable estimation of the Laplacian of the image. A critical graph is constructed using maxima and minima of the Laplacian. Dynamics of critical graphs can be used for diagnostics of dynamical regimes of ARs. The so-called spectral gap is proposed to be used as a numerical descriptor. This is the difference between the two largest eigenvalues of the discrete Laplacian of the graph constructed on critical networks. We investigated several ARs and found that there was a sudden increase in the spectral gap values one or two days before the flares.

  14. Solar spectral conversion for improving the photosynthetic activity in algae reactors.

    PubMed

    Wondraczek, Lothar; Batentschuk, Miroslaw; Schmidt, Markus A; Borchardt, Rudolf; Scheiner, Simon; Seemann, Benjamin; Schweizer, Peter; Brabec, Christoph J

    2013-01-01

    Sustainable biomass production is expected to be one of the major supporting pillars for future energy supply, as well as for renewable material provision. Algal beds represent an exciting resource for biomass/biofuel, fine chemicals and CO2 storage. Similar to other solar energy harvesting techniques, the efficiency of algal photosynthesis depends on the spectral overlap between solar irradiation and chloroplast absorption. Here we demonstrate that spectral conversion can be employed to significantly improve biomass growth and oxygen production rate in closed-cycle algae reactors. For this purpose, we adapt a photoluminescent phosphor of the type Ca0.59Sr0.40Eu0.01S, which enables efficient conversion of the green part of the incoming spectrum into red light to better match the Qy peak of chlorophyll b. Integration of a Ca0.59Sr0.40Eu0.01S backlight converter into a flat panel algae reactor filled with Haematococcus pluvialis as a model species results in significantly increased photosynthetic activity and algae reproduction rate. PMID:23797513

  15. Investigation of a cloud-cover modification to SPCTRAL2, SERI's simple model for cloudless-sky, spectral solar irradiance

    SciTech Connect

    Bird, R.E.; Riordan, C.J.; Myers, D.R.

    1987-06-01

    This report summarizes the investigation of a cloud-cover modification to SPCTRAL2, SERI's simple model for cloudless-sky, spectral solar irradiance. Our approach was to develop a modifier that relies on commonly acquired meteorological and broadband-irradiance data rather than detailed cloud properties that are generally not available. The method was to normalize modeled, cloudless-sky spectral irradiance to a measured broadband-irradiance value under cloudy skies, and then to compare the normalized, modeled data with measured spectral-irradiance data to empirically derive spectral modifiers that improve the agreement between modeled and measured data. Results indicate the possible form of the spectral corrections; however, we must analyze additional data to develop a spectral transmission function for cloudy-sky conditions.

  16. On the temporal variability of the surface solar radiation by means of spectral representations

    NASA Astrophysics Data System (ADS)

    Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

    2016-07-01

    This work deals with the temporal variability of daily means of the global broadband surface solar irradiance (SSI) impinging on a horizontal plane by studying a decennial time-series of high-quality measurements recorded at a BSRN ground station. Since the data have a non-linear and non-stationary character, two time-frequency-energy representations of signal processing are compared in their ability to resolve the temporal variability of the pyranometric signal. First, the continuous wavelet transform is used to construct the wavelet power spectrum of the data. Second, the adaptive, noise-assisted empirical mode decomposition is employed to extract the intrinsic mode functions of the signal, followed by Hilbert spectral analysis. In both spectral representations, the temporal variability of the SSI is portrayed having clearly distinguishable features: a plateau between scales of two days and two-three months that has decreasing power with increasing scale, a large spectral peak corresponding to the annual variability cycle, and a low power regime in between the previous two. It is shown that the data-driven, noise-assisted method yields a somewhat more sparse representation and that it is a suitable tool for inspecting the temporal variability of SSI measurements.

  17. Coherent Events and Spectral Shape at Ion Kinetic Scales in the Fast Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Lion, Sonny; Alexandrova, Olga; Zaslavsky, Arnaud

    2016-06-01

    In this paper we investigate spectral and phase coherence properties of magnetic fluctuations in the vicinity of the spectral transition from large, magnetohydrodynamic to sub-ion scales using in situ measurements of the Wind spacecraft in a fast stream. For the time interval investigated by Leamon et al. (1998) the phase coherence analysis shows the presence of sporadic quasi-parallel Alfvén ion cyclotron (AIC) waves as well as coherent structures in the form of large-amplitude, quasi-perpendicular Alfvén vortex-like structures and current sheets. These waves and structures importantly contribute to the observed power spectrum of magnetic fluctuations around ion scales; AIC waves contribute to the spectrum in a narrow frequency range whereas the coherent structures contribute to the spectrum over a wide frequency band from the inertial range to the sub-ion frequency range. We conclude that a particular combination of waves and coherent structures determines the spectral shape of the magnetic field spectrum around ion scales. This phenomenon provides a possible explanation for a high variability of the magnetic power spectra around ion scales observed in the solar wind.

  18. Spectral evolution of multiply-impulsive solar bursts. Ph.D. Thesis - Maryland Univ.

    NASA Technical Reports Server (NTRS)

    Karpen, J. T.; Crannell, C. J.; Frost, K. J.

    1978-01-01

    Hard X-ray and microwave observations of multiply-impulsive solar bursts, identified in the OSO-5 data were analyzed. Spectra in both frequency ranges were used to determine whether or not the source properties change from peak to peak within individual bursts. Two categories of microwave spectral behavior were identified: those events during which the microwave turnover frequency and spectral shape remain the same from peak to peak, and those during which the turnover frequency and spectral shape change significantly. These categories correspond to two classes of multiply-impulsive bursts: those for which the emission can be characterized by a constant magnetic field and therefore a single source region, in which case the multiplicity may be due to modulation of the emission process; and those in which groups of component spikes appear to originate in regions of different magnetic-field strengths, corresponding to separate source regions which flare sequentially. Examples of the latter type of events are presented. The discrete flaring regions are analyzed and their spatial separations estimated.

  19. Survey of the spectral properties of turbulence in the solar wind, the magnetospheres of Venus and Earth, at solar minimum and maximum

    NASA Astrophysics Data System (ADS)

    Echim, Marius M.

    2014-05-01

    In the framework of the European FP7 project STORM ("Solar system plasma Turbulence: Observations, inteRmittency and Multifractals") we analyze the properties of turbulence in various regions of the solar system, for the minimum and respectively maximum of the solar activity. The main scientific objective of STORM is to advance the understanding of the turbulent energy transfer, intermittency and multifractals in space plasmas. Specific analysis methods are applied on magnetic field and plasma data provided by Ulysses, Venus Express and Cluster, as well as other solar system missions (e.g. Giotto, Cassini). In this paper we provide an overview of the spectral properties of turbulence derived from Power Spectral Densities (PSD) computed in the solar wind (from Ulysses, Cluster, Venus Express) and at the interface of planetary magnetospheres with the solar wind (from Venus Express, Cluster). Ulysses provides data in the solar wind between 1992 and 2008, out of the ecliptic, at radial distances ranging between 1.3 and 5.4 AU. We selected only those Ulysses data that satisfy a consolidated set of selection criteria able to identify "pure" fast and slow wind. We analyzed Venus Express data close to the orbital apogee, in the solar wind, at 0.72 AU, and in the Venus magnetosheath. We investigated Cluster data in the solar wind (for time intervals not affected by planetary ions effects), the magnetosheath and few crossings of other key magnetospheric regions (cusp, plasma sheet). We organize our PSD results in three solar wind data bases (one for the solar maximum, 1999-2001, two for the solar minimum, 1997-1998 and respectively, 2007-2008), and two planetary databases (one for the solar maximum, 2000-2001, that includes PSD obtained in the terrestrial magnetosphere, and one for the solar minimum, 2007-2008, that includes PSD obtained in the terrestrial and Venus magnetospheres and magnetosheaths). In addition to investigating the properties of turbulence for the minimum

  20. Spectral splitting photovoltaics using perovskite and wideband dye-sensitized solar cells.

    PubMed

    Kinoshita, Takumi; Nonomura, Kazuteru; Jeon, Nam Joong; Giordano, Fabrizio; Abate, Antonio; Uchida, Satoshi; Kubo, Takaya; Seok, Sang Il; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Grätzel, Michael; Segawa, Hiroshi

    2015-01-01

    The extension of the light absorption of photovoltaics into the near-infrared region is important to increase the energy conversion efficiency. Although the progress of the lead halide perovskite solar cells is remarkable, and high conversion efficiency of >20% has been reached, their absorption limit on the long-wavelength side is ∼800 nm. To further enhance the conversion efficiency of perovskite-based photovoltaics, a hybridized system with near-infrared photovoltaics is a useful approach. Here we report a panchromatic sensitizer, coded DX3, that exhibits a broad response into the near-infrared, up to ∼1100 nm, and a photocurrent density exceeding 30 mA cm(-2) in simulated air mass 1.5 standard solar radiation. Using the DX3-based dye-sensitized solar cell in conjunction with a perovskite cell that harvests visible light, the hybridized mesoscopic photovoltaics achieved a conversion efficiency of 21.5% using a system of spectral splitting.

  1. Effects of Spectral Error in Efficiency Measurements of GaInAs-Based Concentrator Solar Cells

    SciTech Connect

    Osterwald, C. R.; Wanlass, M. W.; Moriarty, T.; Steiner, M. A.; Emery, K. A.

    2014-03-01

    This technical report documents a particular error in efficiency measurements of triple-absorber concentrator solar cells caused by incorrect spectral irradiance -- specifically, one that occurs when the irradiance from unfiltered, pulsed xenon solar simulators into the GaInAs bottom subcell is too high. For cells designed so that the light-generated photocurrents in the three subcells are nearly equal, this condition can cause a large increase in the measured fill factor, which, in turn, causes a significant artificial increase in the efficiency. The error is readily apparent when the data under concentration are compared to measurements with correctly balanced photocurrents, and manifests itself as discontinuities in plots of fill factor and efficiency versus concentration ratio. In this work, we simulate the magnitudes and effects of this error with a device-level model of two concentrator cell designs, and demonstrate how a new Spectrolab, Inc., Model 460 Tunable-High Intensity Pulsed Solar Simulator (T-HIPSS) can mitigate the error.

  2. SPATIALLY AND SPECTRALLY RESOLVED OBSERVATIONS OF A ZEBRA PATTERN IN A SOLAR DECIMETRIC RADIO BURST

    SciTech Connect

    Chen Bin; Bastian, T. S.; Gary, D. E.; Jing Ju

    2011-07-20

    We present the first interferometric observation of a zebra-pattern radio burst with simultaneous high spectral ({approx}1 MHz) and high time (20 ms) resolution. The Frequency-Agile Solar Radiotelescope Subsystem Testbed (FST) and the Owens Valley Solar Array (OVSA) were used in parallel to observe the X1.5 flare on 2006 December 14. By using OVSA to calibrate the FST, the source position of the zebra pattern can be located on the solar disk. With the help of multi-wavelength observations and a nonlinear force-free field extrapolation, the zebra source is explored in relation to the magnetic field configuration. New constraints are placed on the source size and position as a function of frequency and time. We conclude that the zebra burst is consistent with a double-plasma resonance model in which the radio emission occurs in resonance layers where the upper-hybrid frequency is harmonically related to the electron cyclotron frequency in a coronal magnetic loop.

  3. Imaging and Spectral Observations of Quasi-periodic Pulsations in a Solar Flare

    NASA Astrophysics Data System (ADS)

    Li, D.; Ning, Z. J.; Zhang, Q. M.

    2015-07-01

    We explore the quasi-periodic pulsations (QPPs) in a solar flare observed by Fermi Gamma-ray Burst Monitor, Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, and Interface Region Imaging Spectrograph (IRIS) on 2014 September 10. QPPs are identified as the regular and periodic peaks on the rapidly varying components, which are the light curves after removing the slowly varying components. The QPPs display only three peaks at the beginning on the hard X-ray emissions, but 10 peaks on the chromospheric and coronal line emissions, and more than seven peaks (each peak corresponds to a type III burst on the dynamic spectra) at the radio emissions. A uniform quasi-period of about 4 minutes is detected among them. AIA imaging observations exhibit that the 4-minute QPPs originate from the flare ribbon and tend to appear on the ribbon front. IRIS spectral observations show that each peak of the QPPs tends to a broad line width and a red Doppler velocity at C i, O iv, Si iv, and Fe xxi lines. Our findings indicate that the QPPs are produced by the non-thermal electrons that are accelerated by the induced quasi-periodic magnetic reconnections in this flare.

  4. IMAGING AND SPECTRAL OBSERVATIONS OF QUASI-PERIODIC PULSATIONS IN A SOLAR FLARE

    SciTech Connect

    Li, D.; Ning, Z. J.; Zhang, Q. M.

    2015-07-01

    We explore the quasi-periodic pulsations (QPPs) in a solar flare observed by Fermi Gamma-ray Burst Monitor, Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, and Interface Region Imaging Spectrograph (IRIS) on 2014 September 10. QPPs are identified as the regular and periodic peaks on the rapidly varying components, which are the light curves after removing the slowly varying components. The QPPs display only three peaks at the beginning on the hard X-ray emissions, but 10 peaks on the chromospheric and coronal line emissions, and more than seven peaks (each peak corresponds to a type III burst on the dynamic spectra) at the radio emissions. A uniform quasi-period of about 4 minutes is detected among them. AIA imaging observations exhibit that the 4-minute QPPs originate from the flare ribbon and tend to appear on the ribbon front. IRIS spectral observations show that each peak of the QPPs tends to a broad line width and a red Doppler velocity at C i, O iv, Si iv, and Fe xxi lines. Our findings indicate that the QPPs are produced by the non-thermal electrons that are accelerated by the induced quasi-periodic magnetic reconnections in this flare.

  5. International Intercomparison of Solar UVR Spectral Measurement Systems in Melbourne in 2013.

    PubMed

    Gies, Peter; Hooke, Rebecca; McKenzie, Richard; O'Hagan, John; Henderson, Stuart; Pearson, Andy; Khazova, Marina; Javorniczky, John; King, Kerryn; Tully, Matt; Kotkamp, Michael; Forgan, Bruce; Rhodes, Stephen

    2015-01-01

    Monitoring ambient solar UVR levels provides information on how much there is in both real time and historically. Quality assurance of ambient measurements of solar UVR is critical to ensuring accuracy and stability and this can be achieved by regular intercomparisons of spectral measurement systems with those of other organizations. In October and November of 2013 a solar UVR spectroradiometer from Public Health England (PHE) was brought to Melbourne for a campaign of intercomparisons with a new Bentham spectrometer of Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) and one at the Australian Bureau of Meteorology (BOM), supported by New Zealand's National Institute for Water and Atmosphere (NIWA). Given all three spectroradiometers have calibrations that are traceable to various national standards, the intercomparison provides a chance to determine measurement uncertainties and traceability that support UV measurement networks in Australia, New Zealand and the UK. UV Index measurements from all three systems were compared and ratios determined for clear sky conditions when the scans from each instrument were within 2 min of each other. While wavelengths below 305 nm showed substantial differences between the PHE unit and the two other systems, overall the intercomparison results were encouraging, with mean differences in measured UV Index between the BOM/NIWA and those of PHE and ARPANSA of <0.1% and 7.5%, respectively. PMID:26147793

  6. Spectral splitting photovoltaics using perovskite and wideband dye-sensitized solar cells

    PubMed Central

    Kinoshita, Takumi; Nonomura, Kazuteru; Joong Jeon, Nam; Giordano, Fabrizio; Abate, Antonio; Uchida, Satoshi; Kubo, Takaya; Seok, Sang Il; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Grätzel, Michael; Segawa, Hiroshi

    2015-01-01

    The extension of the light absorption of photovoltaics into the near-infrared region is important to increase the energy conversion efficiency. Although the progress of the lead halide perovskite solar cells is remarkable, and high conversion efficiency of >20% has been reached, their absorption limit on the long-wavelength side is ∼800 nm. To further enhance the conversion efficiency of perovskite-based photovoltaics, a hybridized system with near-infrared photovoltaics is a useful approach. Here we report a panchromatic sensitizer, coded DX3, that exhibits a broad response into the near-infrared, up to ∼1100 nm, and a photocurrent density exceeding 30 mA cm−2 in simulated air mass 1.5 standard solar radiation. Using the DX3-based dye-sensitized solar cell in conjunction with a perovskite cell that harvests visible light, the hybridized mesoscopic photovoltaics achieved a conversion efficiency of 21.5% using a system of spectral splitting. PMID:26538097

  7. Spectral Properties of Large Gradual Solar Energetic Particle Events. I. Fe, O, and Seed Material

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Mason, G. M.; Dayeh, M. A.; Ebert, R. W.; Mccomas, D. J.; Li, G.; Cohen, C. M. S.; Mewaldt, R. A.; Schwadron, N. A.; Smith, C. W.

    2016-01-01

    We have surveyed ˜0.1-100 MeV nucleon-1 O and Fe fluence spectra during 46 isolated, large gradual SEP events observed at ACE during solar cycles 23 and 24. Most SEP spectra are well represented by the four-parameter Band function with a normalization constant, low-energy spectral slope, high-energy spectral slope, and break energy. The O and Fe spectral slopes are similar and most spectra steepen above the break energy, probably due to common acceleration and transport processes affecting different ion species. SEP spectra above the break energies depend on the origin of the seed population; larger contributions of suprathermal flare material result in higher Fe/O ratios and flatter spectra at higher energies. SEP events with steeper O spectra at low energies and higher break energies are associated with slower coronal mass ejections (CMEs), while those associated with fast (>2000 km s-1) CMEs and ground level enhancements have harder or flatter spectra at low and high energies, and O break energies between ˜1 and 10 MeV nucleon-1. The latter events are enriched in 3He and higher-energy Fe, and have Fe spectra that rollover at significantly lower energies compared with O, probably because Fe ions with smaller Q/M ratios can escape from the distant shock more easily than O ions with larger Q/M ratios. We conclude that SEP spectral properties result from many complex and competing effects, namely Q/M-dependent scattering, shock properties, and the origin of the seed populations, all of which must be taken into account to develop a comprehensive picture of CME-driven shock acceleration of large gradual SEP events.

  8. Spectral Properties of Large Gradual Solar Energetic Particle Events. II. Systematic Q/M Dependence of Heavy Ion Spectral Breaks

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Mason, G. M.; Dayeh, M. A.; Ebert, R. W.; McComas, D. J.; Li, G.; Cohen, C. M. S.; Mewaldt, R. A.; Schwadron, N. A.; Smith, C. W.

    2016-09-01

    We fit ∼0.1–500 MeV nucleon‑1 H–Fe spectra in 46 large solar energetic particle (SEP) events with the double power-law Band function to obtain a normalization constant, low- and high-energy parameters γ a and γ b, and break energy E B, and derive the low-energy spectral slope γ 1. We find that: (1) γ a, γ 1, and γ b are species-independent and the spectra steepen with increasing energy; (2) E B decreases systematically with decreasing Q/M scaling as (Q/M) α ; (3) α varies between ∼0.2–3 and is well correlated with the ∼0.16–0.23 MeV nucleon‑1 Fe/O; (4) in most events, α < 1.4, γ b–γ a > 3, and O E B increases with γ b–γ a; and (5) in many extreme events (associated with faster coronal mass ejections (CMEs) and GLEs), Fe/O and 3He/4He ratios are enriched, α ≥ 1.4, γ b–γ a < 3, and E B decreases with γ b–γ a. The species-independence of γ a, γ 1, and γ b and the Q/M dependence of E B within an event and the α values suggest that double power-law SEP spectra occur due to diffusive acceleration by near-Sun CME shocks rather than scattering in interplanetary turbulence. Using γ 1, we infer that the average compression ratio for 33 near-Sun CME shocks is 2.49 ± 0.08. In most events, the Q/M dependence of E B is consistent with the equal diffusion coefficient condition and the variability in α is driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker than the spectra for extreme events. In contrast, in extreme events, enhanced wave power enables faster CME shocks to accelerate impulsive suprathermal ions more efficiently than ambient coronal ions.

  9. Spectral Properties of Large Gradual Solar Energetic Particle Events. II. Systematic Q/M Dependence of Heavy Ion Spectral Breaks

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Mason, G. M.; Dayeh, M. A.; Ebert, R. W.; McComas, D. J.; Li, G.; Cohen, C. M. S.; Mewaldt, R. A.; Schwadron, N. A.; Smith, C. W.

    2016-09-01

    We fit ˜0.1-500 MeV nucleon-1 H-Fe spectra in 46 large solar energetic particle (SEP) events with the double power-law Band function to obtain a normalization constant, low- and high-energy parameters γ a and γ b, and break energy E B, and derive the low-energy spectral slope γ 1. We find that: (1) γ a, γ 1, and γ b are species-independent and the spectra steepen with increasing energy; (2) E B decreases systematically with decreasing Q/M scaling as (Q/M) α ; (3) α varies between ˜0.2-3 and is well correlated with the ˜0.16-0.23 MeV nucleon-1 Fe/O; (4) in most events, α < 1.4, γ b-γ a > 3, and O E B increases with γ b-γ a; and (5) in many extreme events (associated with faster coronal mass ejections (CMEs) and GLEs), Fe/O and 3He/4He ratios are enriched, α ≥ 1.4, γ b-γ a < 3, and E B decreases with γ b-γ a. The species-independence of γ a, γ 1, and γ b and the Q/M dependence of E B within an event and the α values suggest that double power-law SEP spectra occur due to diffusive acceleration by near-Sun CME shocks rather than scattering in interplanetary turbulence. Using γ 1, we infer that the average compression ratio for 33 near-Sun CME shocks is 2.49 ± 0.08. In most events, the Q/M dependence of E B is consistent with the equal diffusion coefficient condition and the variability in α is driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker than the spectra for extreme events. In contrast, in extreme events, enhanced wave power enables faster CME shocks to accelerate impulsive suprathermal ions more efficiently than ambient coronal ions.

  10. Quality assurance of solar spectral UV-measurements: methods and use of the SHICrivm software tool

    NASA Astrophysics Data System (ADS)

    Williams, J. E.; den Outer, P. N.; Slaper, H.

    2003-04-01

    Ground-based UV-irradiance measurements are crucial for determining the long-term changes and trends in biologically and/or photo-chemically relevant solar UV-radiation reaching the Earth's surface. Such changes in UV-radiation levels have probably occurred and/or are expected due to ozone depletion and climate change. In order to analyse UV-irradiation levels in relation to atmospheric parameters and to facilitate an assessment of the European UV-climate a European database (EUVDatabase) has been set up within the EDUCE-project (EC-contract EVK2-CT-1999-00028). High quality UV-data-sets from across the continent are assessable from the EUVDatabase (http://uv.fmi.fi/uvdb/). An accurate analysis of the UV-climate and long term changes therein requires quality assurance of the spectral data. The SHICrivm software tool (http://www.rivm.nl/shicrivm) is developed to analyse several quality aspects of measured UV-spectra. The SHICrivm tool is applied to over one million spectra from the EUVDatabase and detects for each measured spectrum: the accuracy of the wavelength calibration from 290 up to 500 nm, the lowest detectable irradiance level, the occurrence of non-natural spikes in spectra, deviations in spectral shape, and identifies possible irradiance scale errors in the UV-range. In addition the SHIC-package can be used to correct wavelength scale errors and non-natural spectral spikes. A deconvolution and convolution algorithm is included to improve the comparibility of spectra obtained with different instruments, and to allow a fully comparable analysis of biologically weighted UV-dose for instruments with various spectral characteristics. Within the context of the EDUCE-project data from over 20 UV-monitoring stations are retrieved from the database and a quality assessment is performed using the SHIC-tool. The quality parameters are presented by means of a simple scheme of coloured quality flags. Spectra that meet the WMO-criteria for spectral measurements are

  11. High Spectral Resolution, High Cadence, Imaging X-Ray Microcalorimeters for Solar Physics

    NASA Technical Reports Server (NTRS)

    Bandler, Simon R.; Bailey, Catherine N.; Bookbinder, Jay A.; DeLuca, Edward E.; Chervenak, Jay A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Daniel P.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, Jack E.; Smith, Stephen J.; Smith, Randall K.

    2010-01-01

    High spectral resolution, high cadence, imaging x-ray spectroscopy has the potential to revolutionize the study of the solar corona. To that end we have been developing transition-edge-sensor (TES) based x-ray micro calorimeter arrays for future solar physics missions where imaging and high energy resolution spectroscopy will enable previously impossible studies of the dynamics and energetics of the solar corona. The characteristics of these x-ray microcalorimeters are significantly different from conventional micro calorimeters developed for astrophysics because they need to accommodate much higher count rates (300-1000 cps) while maintaining high energy resolution of less than 4 eV FWHM in the X-ray energy band of 0.2-10 keV. The other main difference is a smaller pixel size (less than 75 x 75 square microns) than is typical for x-ray micro calorimeters in order to provide angular resolution less than 1 arcsecond. We have achieved at energy resolution of 2.15 eV at 6 keV in a pixel with a 12 x 12 square micron TES sensor and 34 x 34 x 9.1 micron gold absorber, and a resolution of 2.30 eV at 6 keV in a pixel with a 35 x 35 micron TES and a 57 x 57 x 9.1 micron gold absorber. This performance has been achieved in pixels that are fabricated directly onto solid substrates, ie. they are not supported by silicon nitride membranes. We present the results from these detectors, the expected performance at high count-rates, and prospects for the use of this technology for future Solar missions.

  12. Spectral Absorption of Solar Radiation by Aerosols during ACE-Asia

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Pilewskie, P.; Pommier, J.; Rabbette, M.; Russell, P. B.; Schmid, B.; Redermann, J.; Higurashi, A.; Nakajima, T.; Quinn, P. K.

    2004-01-01

    As part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), the upward and downward spectral solar radiant fluxes were measured with the Spectral Solar Flux Radiometer (SSFR), and the aerosol optical depth was measured with the Ames Airborne Tracking Sunphotometer (AATS-14) aboard the Center for INterdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. IN this paper, we examine the data obtained for two cases: a moderately thick aerosol layer, 12 April, and a relatively thin aerosol case, 16 April 2001. ON both days, the Twin Otter flew vertical profiles in the Korean Strait southeast of Gosan Island. For both days we determine the aerosol spectral absorption of the layer and estimate the spectral aerosol absorption optical depth and single-scattering albedo. The results for 12 April show that the single-scattering albedo increases with wavelength from 0.8 at 400 nm to 0.95 at 900 nm and remains essentially constant from 950 to 1700 nm. On 16 April the amount of aerosol absorption was very low; however, the aerosol single-scattering albedo appears to decrease slightly with wavelength in the visible region. We interpret these results in light of the two absorbing aerosol species observed during the ACE-asia study: mineral dust and black carbon. The results for 12 April are indicative of a mineral dust-black carbon mixture. The 16 April results are possibly caused by black carbon mixed with nonabsorbing pollution aerosols. For the 12 April case we attempt to estimate the relative contributions of the black carbon particles and the mineral dust particles. We compare our results with other estimates of the aerosol properties from a Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) satellite analysis and aerosol measurements made aboard the Twin Otter, aboard the National Oceanic and Atmospheric Administration Ronald H Brown ship, and at ground sites in Gosan and Japan. The results indicate a relatively complicated aerosol

  13. PEAK FLUX DISTRIBUTIONS OF SOLAR RADIO TYPE-I BURSTS FROM HIGHLY RESOLVED SPECTRAL OBSERVATIONS

    SciTech Connect

    Iwai, K.; Masuda, S.; Miyoshi, Y.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2013-05-01

    Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the radio telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each type-I burst element from complex noise storm spectra that include numerous instances of radio frequency interference (RFI). This algorithm removes RFI from the observed radio spectra by applying a moving median filter along the frequency axis. Burst and continuum components are distinguished by a two-dimensional maximum and minimum search of the radio dynamic spectra. The analysis result shows that each type-I burst element has one peak flux without double counts or missed counts. The peak flux distribution of type-I bursts derived using this algorithm follows a power law with a spectral index between 4 and 5.

  14. On the causes of spectral enhancements in solar wind power spectra

    NASA Technical Reports Server (NTRS)

    Unti, T.; Russell, C. T.

    1976-01-01

    Enhancements in power spectra of the solar-wind ion flux in the frequency neighborhood of 0.5 Hz had been noted by Unti et al. (1973). It was speculated that these were due to convected small-scale density irregularities. In this paper, 54 flux spectra calculated from OGO 5 data are examined. It is seen that the few prominent spectral peaks which occur were not generated by density irregularities, but were due to several different causes, including convected discontinuities and propagating transverse waves. A superposition of many spectra, however, reveals a moderate enhancement at a frequency corresponding to convected features with a correlation length of a proton gyroradius, consistent with the results of Neugebauer (1975).

  15. Solar spectral optical properties of pigments--Part II: survey ofcommon colorants

    SciTech Connect

    Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem

    2004-06-15

    Various pigments are characterized by determination ofparameters S (backscattering) and K (absorption) as functions ofwavelength in the solar spectral range of 300 to 2500 nm. Measured valuesof S for generic titanium dioxide (rutile) white pigment are in roughagreement with values computed from the Mie theory, supplemented by asimple multiple scattering model. Pigments in widespread use areexamined, with particular emphasis on those that may be useful forformulating non-white materials that can reflect the near-infrared (NIR)portion of sunlight, such as the complex inorganic color pigments (mixedmetal oxides). These materials remain cooler in sunlight than comparablecolors. NIR-absorptive pigments are to be avoided. High NIR reflectancecan be produced by a reflective metal substrate, a NIR-reflectiveunderlayer, or directly by the use of a pigment that scatters strongly inthe NIR.

  16. Small Pitch Transition-Edge Sensors with Broadband High Spectral Resolution for Solar Physics

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Adams, J. S.; Eckart, M. E.; Smith, Adams; Bailey, C. N.; Bandler, S. R.; Chevenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.

    2012-01-01

    We are developing small pitch transition-edge sensor (TES) X-ray detectors optimized for solar astronomy. These devices are fabricated on thick Si substrates with embedded Cu heat-sink layer. We use 35 x 35 square micrometers Mo/Au TESs with 4.5 micrometer thick Au absorbers. We have tested devices with different geometric absorber stem contact areas with the TES and surrounding substrate area. This allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between thc stem contact area and a broadening in the spectral line shape indicative of athermal phonon loss. When the contact area is minimized we have obtained exceptional broadband spectral resolution of 1.28 plus or minus 0.03 eV at an energy of 1.5 keV, 1.58 plus or minus 0.07 eV at 5.9 keV and 1.96 plus or minus 0.08 eV at 8 keV. The linearity in the measured gain scale is understood in the context of the longitudinal proximity effect from the electrical bias leads resulting in transition characteristics that are strongly dependent upon TES size.

  17. Measurements of solar spectral downwelling irradiance in the water column of a large reservoir in Portugal

    NASA Astrophysics Data System (ADS)

    Potes, Miguel; João Costa, Maria; Salgado, Rui; Morais, Manuela; Bortoli, Daniele; Kostadinov, Ivan

    2016-04-01

    Periodic profiles of spectral downwelling irradiance were performed at Alqueva reservoir, southeast of Portugal, with a new apparatus developed by the team. The device presents a hemispherical tip (180° of FOV) allowing measurements to be independent of solar zenith angle. It is coupled to a portable spectroradiometer through a fiber bundle driven by a customized frame for protection and to keep the tip pointing to the zenith direction in underwater environment. The profiles obtained can be used to estimate the spectral and broadband light attenuation coefficients in the water column. The attenuation coefficients are relevant for the water surface layer energy budget, in particular, this coefficient is important in the computation of the water surface temperature, which is a key parameter for heat and moisture transfers between the reservoirs and the atmosphere, namely by the lake models. A comparison measurement was performed with this new apparatus (180° of FOV) and the previous device (22° of FOV) in order to demonstrate the importance of using the hemispherical radiance. The comparison show resembling results between both devices, however the previous device tends to underestimate the attenuation coefficient and increase the degree of uncertainty.

  18. High-spectral-resolution Observations of the Solar Chromosphere and Corona

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Bruck, M. A.

    2007-05-01

    We continue to reduce high-spectral-resolution observations of the solar chromosphere from the Swedish 1-m Solar Telescope (SST) and TRACE; and, at the 29 March 2006 total solar eclipse, of the solar corona in the [Fe XIV] green line and the [Fe X] red line. (a) The SST observations in 2006 used the SOUP Lyot filter to observe H-alpha limb spicules in five positions with 128 milliangstrom resolution for velocity imaging with several cameras to allow restoration of even noisy images. One camera is near H-alpha, providing high S/N images for extracting wavefront information. The other is deliberately defocused for Phase Diversity information. We use Multi-Object Multi-Frame Blind Deconvolution (MOMFBD; momfbd.org), assisted by Michiel Van Noort and Mats Löfdahl (Royal Swedish Academy of Sciences) and the CfA Hinode center. Simultaneous TRACE observations show spicules in emission and, silhouetted against the EUV corona, in absorption. (b) Our Fabry-Perot 2006-eclipse coronal spectra were taken with David Rust's (JHUAPL) 0.16 angstrom Y-cut lithium-niobate filter. With Rust and Matthew Noble, the etalon was stepped across the red coronal line every 0.22 angstrom. We present the profile and Doppler shifts of the [Fe X] line. (c) We collected simultaneous 10 Hz observations in the red and green coronal lines at the 2006 eclipse, with the goal of detecting high-frequency intensity oscillations ( 1 Hz), which can be relevant to coronal heating, and to confirm previous results. We present FFT and wavelet analysis of the aligned data. We thank Bryce Babcock and Steven Souza (Williams) for their eclipse collaboration. We acknowledge grants NNG04GK44G, NNG04GE48G, and NN05GG75G from NASA Planetary Astronomy. The eclipse observations were supported by NSF grant ATM-0552116 from the Solar Terrrestrial Program of the Atmospheres Sciences Division. Additional eclipse support was received from National Geographic's Committee on Research and Exploration and Williams's Rob Spring

  19. Spectral Absorption Depth Profile: A Step Forward to Plasmonic Solar Cell Design

    NASA Astrophysics Data System (ADS)

    Hossain, Mohammad K.; Mukhaimer, Ayman W.; Drmosh, Qasem A.

    2016-11-01

    Absorption depth profile, a deterministic and key factor that defines the quality of excitons generation rate in optoelectronic devices, is numerically predicted using finite different time domain analysis. A typical model, nanoparticles array on silicon slab, was devised considering the concept of plasmonic solar cell design. The trend of spectral absorption depth profile distributions at various wavelengths of the solar spectrum, 460 nm, 540 nm, 650 nm, 815 nm, and 1100 nm, was obtained. A stronger and well-distributed absorption profile was obtained at ˜650 nm of the solar spectrum (i.e. ˜1.85 eV, c-Si bandgap), although the absorbing layer was affected more than a half micron depth at shorter wavelengths. Considering the observations obtained from this simulation, we have shown a simple two-step method in fabricating ultra-pure silver (Ag) nanoparticles that can be used as plasmonic nanoscatterers in a thin film solar cell. The morphology and elemental analysis of as-fabricated Ag nanoparticles was confirmed by field emission scanning electron microscope (FESEM) and FESEM-coupled electron diffraction spectroscopy. The size of the as-fabricated Ag nanoparticles was found to range from 50 nm to 150 nm in diameter. Further investigations on structural and optical properties of the as-fabricated specimen were carried out using ultraviolet-visible (UV-Vis) absorption, photoluminesce, and x-ray diffraction (XRD). Preferential growth of ZnO along {002} was confirmed by XRD pattern that was more intense and broadened at increasing annealing temperatures. The lattice parameter c was found to increase, whereas grain size increased with increasing annealing temperature. The optical bandgap was also observed to decrease from 3.31 eV to 3.25 eV at increasing annealing temperatures through UV-Vis measurements. This parallel investigation on optical properties by simulation is in line with experimental studies and, in fact, facilitates devising optimum process cost for

  20. Spectral Absorption Depth Profile: A Step Forward to Plasmonic Solar Cell Design

    NASA Astrophysics Data System (ADS)

    Hossain, Mohammad K.; Mukhaimer, Ayman W.; Drmosh, Qasem A.

    2016-07-01

    Absorption depth profile, a deterministic and key factor that defines the quality of excitons generation rate in optoelectronic devices, is numerically predicted using finite different time domain analysis. A typical model, nanoparticles array on silicon slab, was devised considering the concept of plasmonic solar cell design. The trend of spectral absorption depth profile distributions at various wavelengths of the solar spectrum, 460 nm, 540 nm, 650 nm, 815 nm, and 1100 nm, was obtained. A stronger and well-distributed absorption profile was obtained at ˜650 nm of the solar spectrum (i.e. ˜1.85 eV, c-Si bandgap), although the absorbing layer was affected more than a half micron depth at shorter wavelengths. Considering the observations obtained from this simulation, we have shown a simple two-step method in fabricating ultra-pure silver (Ag) nanoparticles that can be used as plasmonic nanoscatterers in a thin film solar cell. The morphology and elemental analysis of as-fabricated Ag nanoparticles was confirmed by field emission scanning electron microscope (FESEM) and FESEM-coupled electron diffraction spectroscopy. The size of the as-fabricated Ag nanoparticles was found to range from 50 nm to 150 nm in diameter. Further investigations on structural and optical properties of the as-fabricated specimen were carried out using ultraviolet-visible (UV-Vis) absorption, photoluminesce, and x-ray diffraction (XRD). Preferential growth of ZnO along {002} was confirmed by XRD pattern that was more intense and broadened at increasing annealing temperatures. The lattice parameter c was found to increase, whereas grain size increased with increasing annealing temperature. The optical bandgap was also observed to decrease from 3.31 eV to 3.25 eV at increasing annealing temperatures through UV-Vis measurements. This parallel investigation on optical properties by simulation is in line with experimental studies and, in fact, facilitates devising optimum process cost for

  1. Solar thermal drying of apricots: Effect of spectrally-selective cabinet materials on drying rate and quality metrics (abstract)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solar thermal (ST) drying is currently not in widespread commercial use due to concerns about slow drying rates and poor product quality. ST dryer cabinets could be constructed from spectrally-selective materials (materials which transmit only certain sunlight wavelength bands), but these types of ...

  2. Dual-mode spectral convertors as a simple approach for the enhancement of hematite's solar water splitting efficiency

    NASA Astrophysics Data System (ADS)

    Atabaev, Timur Sh.; Vu, Hong Ha Thi; Ajmal, Muhammad; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2015-06-01

    Storing solar energy via a chemical fuel of hydrogen from water splitting represents a clean alternative for petroleum fuel. Thus, it is highly desirable for the production of hydrogen using environment-friendly and cost-effective methods. Most photoelectrodes used for this conversion are semiconductor materials whose band gaps match the UV and visible radiation of solar energy. However, further improvement in electrodes performance may be possible by improving photoabsorption efficiency in near-infrared region. This report represents our attempt to utilize IR photons for water splitting, and thus, spectral convertors were incorporated within the hematite nanorods (NRs) grown directly on a FTO glass. The results demonstrate that incorporation of spectral convertors within the hematite NRs leads to higher efficiency and performance in solar water splitting, because the convertors enable harvesting more photons both at UV and IR regions than conventional hematite.

  3. New Instruments for Spectrally-Resolved Solar Soft X-ray Observations from CubeSats, and Larger Missions

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Shih, A.; Warren, H. P.; DeForest, C. E.; Woods, T. N.

    2015-12-01

    Solar soft X-ray (SXR) observations provide important diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are critical for understanding energy transport. A better understanding of the thermal plasma informs our interpretation of hard X-ray (HXR) observations of nonthermal particles, improving our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection. We introduce a new proposed mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-SDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. An X123-CdTe cadmium-telluride detector is also included for ~5-100 keV HXR spectroscopy with ~0.5-1 keV FWHM resolution. CubIXSS also includes a novel spectro-spatial imager -- the first ever solar imager on a CubeSat -- utilizing a pinhole aperture and X-ray transmission diffraction grating to provide full-Sun imaging from ~0.1 to ~10 keV, with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions, respectively. We discuss scaled versions of these instruments, with greater sensitivity and dynamic range, and significantly improved spectral and spatial resolutions for the imager, for deployment on larger platforms such as Small Explorer missions.

  4. A STUDY OF A NEW INCREASING SUBMILLIMETER SPECTRAL COMPONENT OF AN X28 SOLAR FLARE

    SciTech Connect

    Zhou, A. H.; Li, J. P.; Wang, X. D.

    2011-01-20

    In this paper, we study a novel spectral component that increases with frequency above 200 GHz in an X28 solar flare that occurred on 2003 November 4. A maximum flux density of {approx}20,000 sfu was observed at 405 GHz at main phase. We model its spectra based on gyrosynchrotron (GS) radiation computations in the case of a magnetic dipole field. Our computations show that the new increasing submillimeter spectral component at the main peak P1 can be generated by energetic electrons with a harder spectral index (2.3), low-energy cutoff of 30 keV, and number density of 10{sup 10} cm{sup -3} in a compact source (0.''5 radius) with a strong local magnetic field varying from 780 to 4590 G via GS emission. The associated microwave (MW) spectral component can be produced by energetic electrons via GS emission, but with a 10 keV low-energy cutoff and number density 1.2 x 10{sup 6} cm{sup -3} in an extended source (40'' radius) with mean magnetic field strengths from 100 to 576 G. The MW and submillimeter emission sources, inferred from the magnetic dipole field model, are located in the corona and {approx}1000 km low atmosphere levels above the photosphere, respectively. Energy flux, energy loss rate, and total energy released by energetic electrons are estimated for the first time. It is found that the energy flux can attain values of 7.2 x 10{sup 13} erg cm{sup -2} s{sup -1} in the submillimeter source. This value is four orders higher than that in the MW source. The energies released by electrons in the submillimeter and MW sources reach, respectively, 1.2 x 10{sup 32} and 1.9 x 10{sup 31} erg. The total energy released by energetic electrons is 1.4 x 10{sup 32} erg during the flare in the MW and submillimeter sources. The mean energy released by energetic electrons for a subsecond pulse, i.e., the fragment energy, is estimated to be about 5.2 x 10{sup 26} erg.

  5. 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.

  6. Presence of terrestrial atmospheric gas absorption bands in standard extraterrestrial solar irradiance curves in the near-infrared spectral region.

    PubMed

    Gao, B C; Green, R O

    1995-09-20

    The solar irradiance curves compiled by Wehrli [Physikalisch-Meteorologisches Observatorium Publ. 615 (World Radiation Center, Davosdorf, Switzerland, 1985)] and by Neckel and Labs [Sol. Phys. 90, 205 (1984)] are widely used. These curves were obtained based on measurements of solar radiation from the ground and from aircraft platforms. Contaminations in these curves by atmospheric gaseous absorptions were inevitable. A technique for deriving the transmittance spectrum of the Sun's atmosphere from high-resolution (0.01 cm(-1)) solar occultation spectra measured above the Earth's atmosphere by the use of atmospheric trace molecule spectroscopy (ATMOS) aboard the space shuttle is described. The comparisons of the derived ATMOS solar transmittance spectrum with the two solar irradiance curves show that he curve derived by Wehrli contains many absorption features in the 2.0-2.5-µm region that are not of solar origin, whereas the curve obtained by Neckel and Labs is completely devoid of weak solar absorption features that should be there. An Earth atmospheric oxygen band at 1.268 µm and a water-vapor band near 0.94 µm are likely present in the curve obtained by Wehrli. It is shown that the solar irradiance measurement errors in some narrow spectral intervals can be as large as 20%. An improved solar irradiance spectrum is formed by the incorporation of the solar transmittance spectrum derived from the ATMOS data into the solar irradiance spectrum from Neckel and Labs. The availability of a new solar spectrum from 50 to 50 000 cm(-1) from the U.S. Air Force Phillips Laboratory is also discussed.

  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. An algorithm to evaluate solar irradiance and effective dose rates using spectral UV irradiance at four selected wavelengths.

    PubMed

    Anav, A; Rafanelli, C; Di Menno, I; Di Menno, M

    2004-01-01

    The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Alesund (Svalbard Islands, Norway) and Ushuaia (Tierra del Fuego, Argentina). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectroradiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about +/-2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than approximately 20% for solar zenith angles <50 degrees . PMID:15266087

  9. Investigation of Solar Flares Using Spectrally, Spatially, and Temporally Resolved Observations in Gamma Rays, Hard X Rays, and Microwaves

    NASA Technical Reports Server (NTRS)

    Crannell, Carol Jo; Oegerle, William (Technical Monitor)

    2003-01-01

    The high-energy components of solar flares radiate at a wide range of wavelengths. We are using spatially, spectrally, and temporally resolved hard X-ray, gamma-ray, and microwave observations of solar flares to investigate flare models and to understand the flare acceleration process. The hard X-ray and gamma-ray observations are obtained with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) spacecraft that was launched on February 5, 2002. The microwave observations are obtained with the Owens Valley Radio Observatory (OVRO), which has been dedicated to daily observations of solar flares in microwaves with a five-element interferometer since June 1992. These studies are expected to yield exciting new insights into the fundamental physics of the flare acceleration processes.

  10. Shape, Pose, and Material Recovery of Solar-Illuminated Surfaces from Compressive Spectral-Polarimetric Image Data

    NASA Astrophysics Data System (ADS)

    Prasad, S.; Zhang, Q.; Plemmons, R.

    2013-09-01

    Passive solar illumination of a space object gives rise, in general, to both specular reflections and diffuse scattering which a ground-based imaging system would observe as spatially localized glints and spatially generalized brightness patterns, respectively. The glints have nontrivial polarimetric signatures but their spectral signatures are typically only slightly modified versions of the solar spectrum, while the diffuse, generalized scattering is essentially unpolarized and spatially uniform over a pure material but carries spectral signatures that are characteristic of the surface material content. The spatial shape and extension of a glint about a point at which the surface normal of the underlying smooth mean surface bisects the solar angle in the solar illumination plane are determined directly by the degree of roughness of the underlying mean smooth surface. By contrast, the diffuse scattering is largely independent of the angle of incidence of sunlight locally at a surface point, with a uniform spectral signature. It is this dichotomy of features between specular and diffuse scattering in the spectral-polarimetric data that can permit one to recover rather robustly the three-dimensional (3D) shape, pose, and spectral signature of a solar-reflecting surface from its spatial-spectral-polarimetric brightness data. Indeed, for a smooth mean surface made of a pure material that can be characterized via a low-dimensional parametric shape model and thus permits a highly sparse mathematical description, the recovery of these surface attributes as well as its roughness can be obtained well even from compressive spectral-polarimetric image data obtained using a focal-plane spatial code. Such data can be obtained from systems like the Coded-Aperture Snapshot Spectral Polarimetric Imager (CASSPI) [1]. Here we present a computer-simulation-based analysis of the feasibility of our approach to disentangle the spectral, geometrical, and textural (roughness) attributes

  11. Relationship between the durations of jumps in solar wind time series and the frequency of the spectral break

    NASA Astrophysics Data System (ADS)

    Podesta, John J.; Borovsky, Joseph E.

    2016-03-01

    Several physically motivated examples of stochastic processes that exhibit discontinuous jumps at random times are used to show that if the discontinuous jumps are replaced by continuous or smooth transitions with an average duration Δt, then the power spectral density of the process develops a high-frequency spectral break at a frequency of order ωb = π/Δt. Conversely, if the spectrum of the original process is altered by imposing a high-frequency spectral break, as may be accomplished by filtering with a low-pass filter of some kind, then the discontinuous jumps in the original signal are replaced by continuous jumps having a duration of magnitude Δt = π/ωb, where ωb is the break frequency of the altered spectrum. These results suggest that for any stochastic process containing randomly occurring jumps in the time domain and a high-frequency spectral break in the spectral domain with break frequency ωb, the average durations of the jumps are of order Δt = π/ωb. This result is closely connected with the sampling theorem and the uncertainty principle for Fourier transform pairs and demonstrates that the physical processes responsible for the dissipation of solar wind turbulence also determine the thicknesses of the strongest current sheets in the solar wind.

  12. Ultraviolet spectral distribution and erythema-weighted irradiance from indoor tanning devices compared with solar radiation exposures.

    PubMed

    Sola, Yolanda; Baeza, David; Gómez, Miguel; Lorente, Jerónimo

    2016-08-01

    Concern regarding the impact of indoor tanning devices on human health has led to different regulations and recommendations, which set limits on erythema-weighted irradiance. Here, we analyze spectral emissions from 52 tanning devices in Spanish facilities and compare them with surface solar irradiance for different solar zenith angles. Whereas most of the devices emitted less UV-B radiation than the midday summer sun, the unweighted UV-A irradiance was 2-6 times higher than solar radiation. Moreover, the spectral distributions of indoor devices were completely different from that of solar radiation, differing in one order of magnitude at some UV-A wavelengths, depending on the lamp characteristics. In 21% of the devices tested, the erythema-weighted irradiance exceeded 0.3Wm(-2): the limit fixed by the European standard and the Spanish regulation. Moreover, 29% of the devices fall within the UV type 4 classification, for which medical advice is required. The high variability in erythema-weighted irradiance results in a wide range of exposure times to reach 1 standard erythemal dose (SED: 100Jm(-2)), with 62% of devices requiring exposures of <10min to reach 1 SED. Nevertheless, the unweighted UV-A dose during this time period would be from 1.4 to 10.3 times more than the solar UV-A dose. PMID:27318601

  13. Ultraviolet spectral distribution and erythema-weighted irradiance from indoor tanning devices compared with solar radiation exposures.

    PubMed

    Sola, Yolanda; Baeza, David; Gómez, Miguel; Lorente, Jerónimo

    2016-08-01

    Concern regarding the impact of indoor tanning devices on human health has led to different regulations and recommendations, which set limits on erythema-weighted irradiance. Here, we analyze spectral emissions from 52 tanning devices in Spanish facilities and compare them with surface solar irradiance for different solar zenith angles. Whereas most of the devices emitted less UV-B radiation than the midday summer sun, the unweighted UV-A irradiance was 2-6 times higher than solar radiation. Moreover, the spectral distributions of indoor devices were completely different from that of solar radiation, differing in one order of magnitude at some UV-A wavelengths, depending on the lamp characteristics. In 21% of the devices tested, the erythema-weighted irradiance exceeded 0.3Wm(-2): the limit fixed by the European standard and the Spanish regulation. Moreover, 29% of the devices fall within the UV type 4 classification, for which medical advice is required. The high variability in erythema-weighted irradiance results in a wide range of exposure times to reach 1 standard erythemal dose (SED: 100Jm(-2)), with 62% of devices requiring exposures of <10min to reach 1 SED. Nevertheless, the unweighted UV-A dose during this time period would be from 1.4 to 10.3 times more than the solar UV-A dose.

  14. Structure, optical properties and thermal stability of Al2O3-WC nanocomposite ceramic spectrally selective solar absorbers

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Hu; Wang, Cheng-Bing; Guo, Zhi-Ming; Geng, Qing-Fen; Theiss, Wolfgang; Liu, Gang

    2016-08-01

    Traditional metal-dielectric composite coating has found important application in spectrally selective solar absorbers. However, fine metal particles can easily diffuse, congregate, or be oxidized at high temperature, which causes deterioration in the optical properties. In this work, we report a new spectrally selective solar absorber coating, composed of low Al2O3 ceramic volume fraction (Al2O3(L)-WC) layer, high Al2O3 ceramic volume fraction (Al2O3(H)-WC layer) and Al2O3 antireflection layer. The features of our work are: 1) compared with the metal-dielectric composites concept, Al2O3-WC nanocomposite ceramic successfully achieves the all-ceramic concept, which exhibits a high solar absorptance of 0.94 and a low thermal emittance of 0.08, 2) Al2O3 and WC act as filler material and host material, respectively, which are different from traditional concept, 3) Al2O3-WC nanocomposite ceramic solar absorber coating exhibits good thermal stability at 600 °C. In addition, the solar absorber coating is successfully modelled by a commercial optical simulation programme, the result of which agrees with the experimental results.

  15. 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.

  16. Spectral Analyses and Radiation Exposures from Several Ground-Level Enhancement (GLE) Solar Proton Events: A Comparison of Methodologies

    NASA Technical Reports Server (NTRS)

    Atwell, William; Tylka, Allan; Dietrich, William; Badavi, Francis; Rojdev, Kristina

    2011-01-01

    Several methods for analyzing the particle spectra from extremely large solar proton events, called Ground-Level Enhancements (GLEs), have been developed and utilized by the scientific community to describe the solar proton energy spectra and have been further applied to ascertain the radiation exposures to humans and radio-sensitive systems, namely electronics. In this paper 12 GLEs dating back to 1956 are discussed, and the three methods for describing the solar proton energy spectra are reviewed. The three spectral fitting methodologies are EXP [an exponential in proton rigidity (R)], WEIB [Weibull fit: an exponential in proton energy], and the Band function (BAND) [a double power law in proton rigidity]. The EXP and WEIB methods use low energy (MeV) GLE solar proton data and make extrapolations out to approx.1 GeV. On the other hand, the BAND method utilizes low- and medium-energy satellite solar proton data combined with high-energy solar proton data deduced from high-latitude neutron monitoring stations. Thus, the BAND method completely describes the entire proton energy spectrum based on actual solar proton observations out to 10 GeV. Using the differential spectra produced from each of the 12 selected GLEs for each of the three methods, radiation exposures are presented and discussed in detail. These radiation exposures are then compared with the current 30-day and annual crew exposure limits and the radiation effects to electronics.

  17. A New SATIRE-S Spectral Solar Irradiance Reconstruction for Solar Cycles 21-23 and Its Implications for Stratospheric Ozone*

    NASA Astrophysics Data System (ADS)

    Ball, William T.; Krivova, Natalie A.; Unruh, Yvonne C.; Haigh, Joanna D.; Solanki, Sami K.

    2014-11-01

    We present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the SATIRE-S model. The SSI reconstruction covers wavelengths between 115 and 160,000 nm and all dates between August 1974 and October 2009. This represents the first full-wavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the NRLSSI model and SORCE/SOLSTICE ultraviolet (UV) observations. SATIRE-S displays similar cycle behaviour to NRLSSI for wavelengths below 242 nm and almost twice the variability between 242 and 310 nm. During the decline of last solar cycle, between 2003 and 2008, SSI from SORCE/SOLSTICE version 12 and 10 typically displays more than three times the variability of SATIRE-S between 200 and 300 nm. All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modelled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE/SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE/SOLSTICE irradiances. The recalibrated SORCE/SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than when using version 10 and now similar in magnitude to SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient to warrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.

  18. Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors

    NASA Technical Reports Server (NTRS)

    Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B.; Allen, Maxwell J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C., Jr.

    1991-01-01

    The Multispectral Solar Telescope Array is a rocket-borne observatory which encompasses seven compact soft X-ray/EUV, multilayer-coated, and two compact far-UV, interference film-coated, Cassegrain and Ritchey-Chretien telescopes. Extensive measurements are presented on the efficiency and spectral bandpass of the X-ray/EUV telescopes. Attention is given to systematic errors and measurement errors.

  19. Solar Spectral Irradiance Measured from 11.58 km with a Leiss Monochromator and a Photoelectric Filter Radiometer.

    PubMed

    Webb, J J; Duncan, C H; McIntosh, R; Lester, D

    1970-02-01

    Solar spectral irradiance measurements were made from NASA's Convair 990 research aircraft using a Leiss double prism monochromator and a GSFC modified Eppley Mark V radiometer. Six flights were made over the Pacific and western United States at an altitude of 11.58 km. Excellent agreement is noted between the two instruments through a wavelength range of 0.3-1.1 micro, even though they are optically and electronically dissimilar. Instrument calibrations were performed in flight using an NBS type quartz-iodine standard of spectral irradiance. Extrapolation to zero air mass was facilitated by the fact that at 11.58 km the aircraft was above 80% of the permanent gases of the atmosphere and more importantly above 99.9% of the water vapor and all the atmospheric pollutants. The resulting solar spectral curves differ significantly from Johnson's in several regions. Solar constant measurements made with other flight instruments resulted in a value of 0.1351 W cm(-2), which is about 3.3% less than Johnson's, but is in good agreement with recently published values of Drummond, Laue, and others.

  20. Simulation for spectral response of solar-blind AlGaN based p-i-n photodiodes

    NASA Astrophysics Data System (ADS)

    Xue, Shiwei; Xu, Jintong; Li, Xiangyang

    2015-04-01

    In this article, we introduced how to build a physical model of refer to the device structure and parameters. Simulations for solar-blind AlGaN based p-i-n photodiodes spectral characteristics were conducted in use of Silvaco TCAD, where device structure and parameters are comprehensively considered. In simulation, the effects of polarization, Urbach tail, mobility, saturated velocities and lifetime in AlGaN device was considered. Especially, we focused on how the concentration-dependent Shockley-Read-Hall (SRH) recombination model affects simulation results. By simulating, we analyzed the effects in spectral response caused by TAUN0 and TAUP0, and got the values of TAUN0 and TAUP0 which can bring a result coincides with test results. After that, we changed their values and made the simulation results especially the part under 255 nm performed better. In conclusion, the spectral response between 200 nm and 320 nm of solar-blind AlGaN based p-i-n photodiodes were simulated and compared with test results. We also found that TAUN0 and TAUP0 have a large impact on spectral response of AlGaN material.

  1. Absolute Solar EUV Irradiance Measurements Obtained on NASA Sounding Rocket Flights 36.286 (23 June 2012) and 36.263 (24 July 2012) For Comparison with Solar EUV Irradiance Measurements from the EUV Spectrophotometer (ESP) Onboard the SDO/EVE and with the Solar EUV Monitor (SEM) Onboard the SOHO/CELIAS

    NASA Astrophysics Data System (ADS)

    Didkovsky, L. V.; Wieman, S. R.; Judge, D. L.; Woods, T. N.

    2012-12-01

    Two sounding rocket flights, SDO/EVE under-flight NASA 36.286 (23 June 2012) and Degradation-Free solar Spectrometers NASA 36.263 (24 July 2012) provided high-quality EUV data for comparison with the SDO/EVE EUV Spectrophotometer (ESP) and SOHO/CELIAS/SEM Solar Irradiance Measurements. These two rocket flights allowed us to compare flight and rocket solar EUV irradiances during relatively quiet solar conditions (36.286) and during a C4 solar flare (36.263). The results of these comparisons are presented and discussed using two types of solar reference spectra, a time independent SOLERS-22 spectrum built for moderate solar activity, and currently available EVE spectra representing spectral variability of the dynamical Sun.

  2. 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.

  3. 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].

  4. Using Spectral Shape and Predictor Fluence to Evaluate Temporal Exposures to Solar Particle Events

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Blattnig, Steve R.

    2016-01-01

    Real-time estimation of exposure levels has been considered in NASA's operational strategies and structural capability for the protection of astronauts from exposure to large solar particle events (SPEs) with high energy levels. The temporal profile of dose rates is also important for the analysis of dose-rate-dependent biological responses, the improvement of radiation protection by minimizing the overall exposure levels at sensitive organ sites, and the optimization of future mission planning. However, making a realistic temporal estimation in a timely manner has not been readily available because the exposure analysis relies on required components. They include the complete energy spectrum of SPE to define the boundary condition for radiation transport simulation, the radiation transport code with detailed shielding and body geometry models to determine particle transmission into areas of internal shielding and at each critical body organ, and the assessment of organ dosimetric quantities and biological risks by applying the corresponding response models for space radiation against the particle spectra that have been accurately determined from the transport code. This paper introduces the process of estimating temporal exposures to SPEs by implementing the distributions of the organ doses and the spectral shape dependencies of the major SPEs. The probability that a dose to a blood-forming organ will exceed the NASA limit is simultaneously calculated by taking into account the variability of detailed spectra of SPEs at a given temporal flux. These temporal evaluations of SPEs can be applied to the development of real-time guidance on improving mitigation of adverse effects during space missions.

  5. Optical Spectral Observations of a Flickering White-light Kernel in a C1 Solar Flare

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam F.; Cauzzi, Gianna; Fletcher, Lyndsay

    2015-01-01

    We analyze optical spectra of a two-ribbon, long-duration C1.1 flare that occurred on 2011 August 18 within AR 11271 (SOL2011-08-18T15:15). The impulsive phase of the flare was observed with a comprehensive set of space-borne and ground-based instruments, which provide a range of unique diagnostics of the lower flaring atmosphere. Here we report the detection of enhanced continuum emission, observed in low-resolution spectra from 3600 Å to 4550 Å acquired with the Horizontal Spectrograph at the Dunn Solar Telescope. A small, <=0.''5 (1015 cm2) penumbral/umbral kernel brightens repeatedly in the optical continuum and chromospheric emission lines, similar to the temporal characteristics of the hard X-ray variation as detected by the Gamma-ray Burst Monitor on the Fermi spacecraft. Radiative-hydrodynamic flare models that employ a nonthermal electron beam energy flux high enough to produce the optical contrast in our flare spectra would predict a large Balmer jump in emission, indicative of hydrogen recombination radiation from the upper flare chromosphere. However, we find no evidence of such a Balmer jump in the bluemost spectral region of the continuum excess. Just redward of the expected Balmer jump, we find evidence of a "blue continuum bump" in the excess emission which may be indicative of the merging of the higher order Balmer lines. The large number of observational constraints provides a springboard for modeling the blue/optical emission for this particular flare with radiative-hydrodynamic codes, which are necessary to understand the opacity effects for the continuum and emission line radiation at these wavelengths.

  6. OPTICAL SPECTRAL OBSERVATIONS OF A FLICKERING WHITE-LIGHT KERNEL IN A C1 SOLAR FLARE

    SciTech Connect

    Kowalski, Adam F.; Cauzzi, Gianna; Fletcher, Lyndsay

    2015-01-10

    We analyze optical spectra of a two-ribbon, long-duration C1.1 flare that occurred on 2011 August 18 within AR 11271 (SOL2011-08-18T15:15). The impulsive phase of the flare was observed with a comprehensive set of space-borne and ground-based instruments, which provide a range of unique diagnostics of the lower flaring atmosphere. Here we report the detection of enhanced continuum emission, observed in low-resolution spectra from 3600 Å to 4550 Å acquired with the Horizontal Spectrograph at the Dunn Solar Telescope. A small, ≤0.''5 (10{sup 15} cm{sup 2}) penumbral/umbral kernel brightens repeatedly in the optical continuum and chromospheric emission lines, similar to the temporal characteristics of the hard X-ray variation as detected by the Gamma-ray Burst Monitor on the Fermi spacecraft. Radiative-hydrodynamic flare models that employ a nonthermal electron beam energy flux high enough to produce the optical contrast in our flare spectra would predict a large Balmer jump in emission, indicative of hydrogen recombination radiation from the upper flare chromosphere. However, we find no evidence of such a Balmer jump in the bluemost spectral region of the continuum excess. Just redward of the expected Balmer jump, we find evidence of a ''blue continuum bump'' in the excess emission which may be indicative of the merging of the higher order Balmer lines. The large number of observational constraints provides a springboard for modeling the blue/optical emission for this particular flare with radiative-hydrodynamic codes, which are necessary to understand the opacity effects for the continuum and emission line radiation at these wavelengths.

  7. The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Hu, LiWen; Wang, Fang; Gao, YanYan; Zheng, Yang; Wang, Yu; Liu, Yang

    2016-01-01

    To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.

  8. Requirements of a solar diffuser and measurements of some candidate materials. [for calibration of satellite sensors

    NASA Technical Reports Server (NTRS)

    Guzman, Carmen T.; Palmer, James M.; Slater, Philip N.; Bruegge, Carol J.; Miller, Edward A.

    1991-01-01

    If the solar spectral irradiance and the orientation and directional reflectance of a solar diffuser are known, then the spectral radiance of the diffuser is readily calculated and it can be used for the accurate absolute calibration of a satellite sensor. However, the solar diffuser is exposed during in-flight satellite sensor calibration to high-energy ultraviolet irradiance, particle impacts and atomic oxygen effects. This paper describes desirable solar diffuser characteristics and the results of proton and UV irradiation on the directional-hemispheric spectral reflectance, the bidirectional spectral reflectance factor and the polarization properties of candidate diffuser materials.

  9. Absolute dimensions of solar-type eclipsing binaries. III. EW Orionis: stellar evolutionary models tested by a G0 V system

    NASA Astrophysics Data System (ADS)

    Clausen, J. V.; Bruntt, H.; Olsen, E. H.; Helt, B. E.; Claret, A.

    2010-02-01

    Context. Recent studies of inactive and active solar-type binaries suggest that chromospheric activity, and its effect on envelope convection, is likely to cause significant radius and temperature discrepancies. Accurate mass, radius, and abundance determinations from additional solar-type binaries exhibiting various levels of activity are needed for a better insight into the structure and evolution of these stars. Aims: We aim to determine absolute dimensions and abundances for the G0 V detached eclipsing binary EW Ori, and to perform a detailed comparison with results from recent stellar evolutionary models. Methods: uvby light curves and {uvby}β standard photometry were obtained with the Strömgren Automatic Telescope, published radial velocity observations from the CORAVEL spectrometer were reanalysed, and high-resolution spectra were observed at the FEROS spectrograph; all are/were ESO, La Silla facilities. State-of-the-art methods were applied for the photometric and spectroscopic analyses. Results: Masses and radii that are precise to 0.9% and 0.5%, respectively, have been established for both components of EW Ori. The 1.12 M⊙ secondary component reveals weak Ca ii H and K emission and is probably mildly active; no signs of activity are seen for the 1.17 M⊙ primary. We derive an [Fe/H] abundance of +0.05 ± 0.09 and similar abundances for Si, Ca, Sc, Ti, Cr, and Ni. Yonsai-Yale and Granada solar-scaled evolutionary models for the observed metal abundance reproduce the components fairly well at an age of ≈2 Gyr. Perfect agreement is, however, obtained at an age of 2.3 Gyr for a combination of a) a slight downwards adjustment of the envelope mixing length parameter for the secondary, as seen for other active solar-type stars; and b) a slightly lower helium content than prescribed by the Y-Z relations adopted for the standard model grids. The orbit is eccentric (e = 0.0758 ± 0.0020), and apsidal motion with a 62% relativistic contribution has been

  10. Correlations of solar cycle 22 UV irradiance

    NASA Technical Reports Server (NTRS)

    Floyd, L.; Brueckner, G.; Crane, P.; Prinz, D.; Herring, L.

    1997-01-01

    The solar ultraviolet spectral irradiance monitor (SUSIM) onboard the upper atmosphere research satellite (UARS) is an absolutely calibrated UV spectrometer which has measured the solar spectral irradiance over the wavelengths 115 nm to 410 nm since October 1991. This data set now extends for about six years from near the peak of solar cycle 22, through its minimum, to the initial rise associated with solar cycle 23. Generally, the time series of UV spectral irradiances obtained shows behavior similar to that of other solar activity indices. The conditions on the sun, which can in result in dominant 13.5-day periodicity, are analyzed and illustrated. It is found that any combination of presence or absence of dominant 13.5-day in UV irradiance and solar wind velocity is possible depending entirely on the particular surface distribution and orientation of solar active regions.

  11. Construction of a SORCE-based Solar Spectral Irradiance (SSI) Record for Input into Chemistry Climate Models

    NASA Astrophysics Data System (ADS)

    Harder, J. W.; Fontenla, J. M.

    2015-12-01

    We present a research program to produce a solar spectral irradiance (SSI) record suitable for whole atmosphere chemistry-climate model (CCM) transient studies over the 2001-2015 time period for Solar Cycle 23 and 24 (SC23-24). Climate simulations during this time period are particularly valuable because SC23-24 represents the best-observed solar cycle in history - both from the perspective of solar physics and in terms of Earth observation systems. This record will be based predominantly on the observed irradiance of the SORCE mission as measured by the SIM and SOLSTICE instruments from April of 2003 to the present time. The SSI data record for this proposed study requires very broad wavelength coverage (115-100000 nm), daily spectral coverage, compliance of the integrated SSI record with the TSI, and well-defined and documented uncertainty estimates. While the majority of the record will be derived from SORCE observations, extensions back to the SC23 maximum time period (early 2001) and closure of critical gaps in the SORCE record will be generated employing the Fontenla et al. (2015) Solar Radiation Physical Model (SRPMv2). Since SRPM is a physics-based model, estimates of the SSI for wavelengths outside the SORCE measurement range can be meaningfully included. This model now includes non-LTE contributions from metals in the atomic number range 22-28 (i.e. titanium through nickel) as well as important molecular photo-disassociation contributions from molecules such as NH, molecular hydrogen, CH, and OH led have led to greatly improved agreement between the model and the observed 0.1 nm SOLSTICE spectrum. Thus comparative studies of the SORCE observations with SRPMv2 provide meaningful insight into the nature of solar variability critical for subsequent Earth atmospheric modeling efforts.

  12. Tandem Polymer Solar Cells Featuring a Spectrally Matched Low-Bandgap Polymer

    SciTech Connect

    Dou, L.; You, J.; Yang, J.; Chen, C. C.; He, Y.; Murase, S.; Moriarty, T.; Emery, K.; Li, G.; Yang, Y.

    2012-03-01

    Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of a suitable low-bandgap polymer. Here, we demonstrate highly efficient single and tandem polymer solar cells featuring a low-bandgap conjugated polymer (PBDTT-DPP: bandgap, {approx}1.44 eV). A single-layer device based on the polymer provides a power conversion efficiency of {approx}6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which is, to the best of our knowledge, the highest certified efficiency for a polymer solar cell to date.

  13. The dynamics and spectral characteristics of the GPS TEC wave packets excited by the solar terminator

    NASA Astrophysics Data System (ADS)

    Afraimovich, E. L.; Edemsky, I. K.; Voeykov, S. V.; Yasukevich, Y. V.; Zhivetiev, I. V.

    2009-04-01

    The great variety of solar terminator (ST) -linked phenomena in the atmosphere gave rise to a num¬ber of studies on the analysis of ionosphere parameter variations obtained by different ionosphere sounding methods. Main part of experimental data was obtained using methods for analyzing the spectrum of ionosphere parameter variations in separate local points. To identify ST-generated wave disturbances it is necessary to measure the dynamic and spectral characteristics of the wave disturbances and to compare it with spatial-temporal characteristics of ST. Using TEC measurements from the dense network of GPS sites GEONET (Japan), we have obtained the first GPS-TEC image of the space structure of medium-scale traveling wave packets (MS TWP) excited by the solar terminator. We use two known forms of the 2D GPS-TEC image for our presentation of the space structure of ST-generated MS TWP: 1) - the diagram "distance-time"; 2) - the 2D-space distribution of the values of filtered TEC series dI (λ, φ, t) on the latitude φ and longitude λ for each 30-sec TEC counts. We found that the time period and wave-length of ST-generated wave packets are about 10-20 min and 200-300 km, respectively. Dynamic images analysis of dI (λ, φ, t) gives precise estimation of velocity and azimuth of TWP wave front propagation. We use the method of determining velocity of traveling ionosphere disturbances (SADM-GPS), which take into account the relative moving of subionosphere points. We found that the velocity of the TWP phase front, traveling along GEONET sites, varies in accordance with the velocity of the ST line displacement. The space image of MS TWP manifests itself in pronounced anisotropy and high coherence over a long distance of about 2000 km. The TWP wave front extends along the ST line with the angular shift of about 20°. The hypothesis on the connection between the TWP generation and the solar terminator can be tested in the terminator local time (TLT) system: d

  14. Daily spectral effects on concentrating PV solar cells as affected by realistic aerosol optical depth and other atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Gueymard, Christian A.

    2009-08-01

    This contribution addresses the need for more information about the spectral effect affecting solar cells specifically designed for concentrating photovoltaic (CPV) applications. Spectral effects result from differences between the actual (dynamically variable) solar spectrum incident on a solar cell in the field and the standard (fixed) solar spectrum used for rating purposes. A methodology is proposed to quantify this spectral effect at any site where basic atmospheric information exists, and predict what semiconductor material(s) may benefit from operating under non-standard conditions. Using the same SMARTS radiative code as for the development of the improved reference spectrum for concentrating PV rating, an analysis of the spectral sensitivity of five specific PV technologies to varying atmospheric factors is presented, using simulated spectra at 5-nm resolution. (The alternative of using the average photon energy (APE) concept was also considered, but proved inappropriate in the present context.) The technologies investigated here include a 21.5%-efficient CIGS cell, a 22%-efficient crystalline silicon cell (both appropriate for low-concentration applications), as well as three high-performance multijunction cells, which are specifically designed for high-concentration applications. To the difference of most previous studies, the approach taken here considers realistic atmospheric conditions. The proposed Daily Spectral Enhancement Factor (DSEF) is obtained from a typical daily-average incident spectrum, which is purposefully weighted to minimize the incidence of large spectral effects at low sun. Calculations of DSEF are performed here at fifteen world sites from an atmospheric monitoring network. These sites have largely different latitudes and climates, and yet are all potentially interesting for CPV applications. Results are obtained for a typical clear day of January and July, and for each of the five PV technologies just mentioned. This analysis

  15. Investigating the ion-scale spectral properties of solar wind turbulence with high-resolution hybrid simulations

    NASA Astrophysics Data System (ADS)

    Franci, L.; Landi, S.; Matteini, L.; Verdini, A.; Hellinger, P.

    2015-12-01

    We investigate the properties of the solar wind turbulence from MHD to sub-ion scales by means of two-dimensional, large-scale, high-resolution hybrid particle-in-cell simulations. These constitute the most accurate hybrid simulations of ion-scale turbulence ever presented so far, and let us explore a very wide range of scales, i.e., three decades in wave vectors simultaneously. We impose an initial ambient magnetic field perpendicular to the simulation box, and we add a spectrum of in-plane large-scale magnetic and kinetic fluctuations, with energy equipartition and vanishing correlation. We perform a set of simulations with many different values of two fundamental parameters, i.e., the plasma beta, β, and the amplitude of the initial fluctuations, Brms, in order to investigate their relevance in determining the spectral properties of the turbulent cascade around ion scales. Once turbulence is fully developed, we observe the power spectrum of the magnetic fluctuations following a power law with a spectral index of -5/3 in the inertial range, with a spectral break around ion scales and a steeper power law in the sub-ion range. The scale at which the steepening of the spectrum occurs changes when exploring the (β,Brms) parameter space. Such a movement of the spectral break is clearer when looking at the spectra of the parallel magnetic fluctuations and of the density fluctuations. Moreover, these share the same power law behavior at sub-ion scales, exhibiting a spectral index of -2.8, which seems to be independent on the values of the two varying parameters. We compare our results with solar wind observations, and we suggest possible explanations for such behavior.

  16. The Sun-Earth connect 1: A fractional d-matrix of solar emissions compared to spectral analysis evidence of solar measurements and climate proxies

    NASA Astrophysics Data System (ADS)

    Baker, Robert G. V.

    2016-02-01

    The possibility that there is a constant ratio underpinning published solar cycles provides an opportunity to explore the harmonics within emission processes. This idea is initially developed by a phenomenological matrix where the elements or emission phases are underpinned by a cyclic fractional dimension d (0.39807) which is shown here to include the fine structure constant (1/137.0356). The Sun's Carrington synodic rotation (27.275d) multiplied by the inverse of the fine structure constant creates elements of this d-matrix which yields possible sequences of self-similar phase periods between harmonic elements of solar emissions. The periodicities of the Carrington rotation is defined by row 1 (R1) and subsequent rows R2,R3,R4 are the potential phase periods of possible twisting permutations of the tachocline. For solar measurements, the first four rows of the matrix predict at least 98% of the top hundred significant periodicities determined from multi-taper spectral analysis of solar data sets (the satellite ACRIM composite irradiance; the terrestrial 10.7cm Penticton Adjusted Daily Radio Flux, Series D; and the historical mean monthly International Sunspot Number). At centennial and millennial time scales, the same matrix predicts 'average' significant periodicities (greater than 95%) reported in 23 published climate data sets. This discovery suggests there is strong empirical evidence for a d-cyclic fractional 'solar clock', where the corresponding spectrum of cycles and switching events are embedded into the historical, climatic and geological records of the Earth.

  17. 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.

  18. Spectral Signature of Column Solar Radiation Absorption During the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE). Revision

    SciTech Connect

    O'Hirok, William; Gautier, Catherine; Ricchiazzi, Paul

    1999-11-01

    Spectral and broadband shortwave radiative flux data obtained from the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) are compared with 3-D radiative transfer computations for the cloud field of October 30, 1995. Because the absorption of broadband solar radiation in the cloudy atmosphere deduced from observations and modeled differ by 135 Wm{sup -2}, we performed a consistency analysis using spectral observations and the model to integrate for wavelengths between the spectral observations. To match spectral measurements, aerosols need a reduction in both single scattering albedo (from 0.938 to 0.82) and asymmetry factor (from 0.67 to 0.61), and cloud droplets require a three-fold increase in co-albedo. Even after modifying the model inputs and microphysics the difference in total broadband absorption is still of the order of 75Wm{sup -2}. Finally, an unexplained absorber centered around 1.06 {micro}m appears in the comparison that is much too large to be explained by dimers.

  19. The making of a new solar spectral irradiance composite - overview of the results from the SOLID Project

    NASA Astrophysics Data System (ADS)

    Haberreiter, M.; Dudok de Wit, T.; Kretzschmar, M.; Schöll, M.; Del Zanna, G.; Ermolli, I.

    2015-12-01

    Solar spectral irradiance (SSI) is a key driver for the Earth's climate system. To understand in detail the processes at play a consistent SSI time series with realistic uncertainty estimates is needed as input for climate models. However, irradiance observations exist only as numerous and disperse data sets. Also, different SSI instruments show varying instrumental noise and degradation. Due to these effects it is a challenge to build a consistent SSI data set. Within the European Project SOLID we developed tools to derive an objective SSI time series based on existing SSI measurements, complemented with reconstruction models. We present the SOLID SSI composite with a focus on the UV spectral range and compare it with other available SSI reconstructions.

  20. Scale-dependent Normalized Amplitude and Weak Spectral Anisotropy of Magnetic Field Fluctuations in the Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Tu, Chuanyi; Marsch, Eckart; He, Jiansen; Wang, Linghua

    2016-01-01

    Turbulence in the solar wind was recently reported to be anisotropic, with the average power spectral index close to -2 when sampling parallel to the local mean magnetic field {{\\boldsymbol{B}}}0 and close to -5/3 when sampling perpendicular to the local {{\\boldsymbol{B}}}0. This result was widely considered to be observational evidence for the critical balance theory (CBT), which is derived by making the assumption that the turbulence strength is close to one. However, this basic assumption has not yet been checked carefully with observational data. Here we present for the first time the scale-dependent magnetic-field fluctuation amplitude, which is normalized by the local {{\\boldsymbol{B}}}0 and evaluated for both parallel and perpendicular sampling directions, using two 30-day intervals of Ulysses data. From our results, the turbulence strength is evaluated as much less than one at small scales in the parallel direction. An even stricter criterion is imposed when selecting the wavelet coefficients for a given sampling direction, so that the time stationarity of the local {{\\boldsymbol{B}}}0 is better ensured during the local sampling interval. The spectral index for the parallel direction is then found to be -1.75, whereas the spectral index in the perpendicular direction remains close to -1.65. These two new results, namely that the value of the turbulence strength is much less than one in the parallel direction and that the angle dependence of the spectral index is weak, cannot be explained by existing turbulence theories, like CBT, and thus will require new theoretical considerations and promote further observations of solar-wind turbulence.

  1. Spectral Kernel Approach to Study Radiative Response of Climate Variables and Interannual Variability of Reflected Solar Spectrum

    NASA Technical Reports Server (NTRS)

    Jin, Zhonghai; Wielicki, Bruce A.; Loukachine, Constantin; Charlock, Thomas P.; Young, David; Noeel, Stefan

    2011-01-01

    The radiative kernel approach provides a simple way to separate the radiative response to different climate parameters and to decompose the feedback into radiative and climate response components. Using CERES/MODIS/Geostationary data, we calculated and analyzed the solar spectral reflectance kernels for various climate parameters on zonal, regional, and global spatial scales. The kernel linearity is tested. Errors in the kernel due to nonlinearity can vary strongly depending on climate parameter, wavelength, surface, and solar elevation; they are large in some absorption bands for some parameters but are negligible in most conditions. The spectral kernels are used to calculate the radiative responses to different climate parameter changes in different latitudes. The results show that the radiative response in high latitudes is sensitive to the coverage of snow and sea ice. The radiative response in low latitudes is contributed mainly by cloud property changes, especially cloud fraction and optical depth. The large cloud height effect is confined to absorption bands, while the cloud particle size effect is found mainly in the near infrared. The kernel approach, which is based on calculations using CERES retrievals, is then tested by direct comparison with spectral measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) (a different instrument on a different spacecraft). The monthly mean interannual variability of spectral reflectance based on the kernel technique is consistent with satellite observations over the ocean, but not over land, where both model and data have large uncertainty. RMS errors in kernel ]derived monthly global mean reflectance over the ocean compared to observations are about 0.001, and the sampling error is likely a major component.

  2. Spectral measurements of ultraviolet and visible solar irradiance at the Weddell-Scotia Confluence during 1993 austral spring

    SciTech Connect

    Sikorski, R.J.; Sigleo, A.C.; Neale, P.J.

    1994-12-31

    Spectral measurements were made of incident and undersea solar irradiance in the October and November 1993 austral spring, during transits of low ozone {open_quotes}hole{close_quotes} over the Weddell-Scotia Confluence. Several scanning radiometers were intercalibrated between research groups and used for measurements of ultraviolet (UV) and visible exposure for in situ processes and for on-deck and in-lab productivity, photoinhibition, and photochemistry experiments. The intercalibration of instruments also gave valuable information for comparison of data from various published and unpublished sources. 2 refs., 3 figs., 1 tab.

  3. Spectral properties of water ice and contaminants. [of importance to remote sensing of ice in solar system

    NASA Technical Reports Server (NTRS)

    Lucey, P. G.; Clark, R. N.

    1985-01-01

    For remote sensing studies of ices in the solar system, it is important to understand the optical properties of water ice, and mixtures of ice and particulate materials. The present paper has the objective to review the current understanding of the spectral properties of ice, and mixtures of ice and particulates. The review is to provide a basis for the understanding of the remote sensing of ice. It is found that reflectance spectra of ice-soil intimate mixtures are complex, nonlinear functions of the optical and physical properties of the components which comprise the surface.

  4. Measures of the solar spectral irradiance between 1200 and 3000 A. [tables (data)

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Thekaekara, M. P.

    1976-01-01

    Tabulated data on solar flux measurements are presented. The measurements, taken from balloons, rockets and satellites, are not new data, but have been critically re-evaluated. The eleven year sunspot cycle is discussed. Also discussed is the brightness temperature. The effect of solar radiation at various wavelengths, on the photochemistry of stratospheric ozone is briefly discussed.

  5. [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.

  6. Spectral Characterization of Solar Active Region NOAA 8242 in Quiet and Sunspot Locations

    NASA Astrophysics Data System (ADS)

    Janve, Vaibhav A.; Ambastha, Ashok

    2005-09-01

    We present results from the analysis of simultaneous Stokes I profile measurements in Fe I twin line in 6302 Å region and Ca II K 3934 Å line over NOAA 8242 on 13th June 1998. Advanced Stokes Polarimeter (ASP) instrument of the Vacuum Tower Telescope (VTT) of Sac Peak, NSO, U.S.A was used for obtaining these observations. Along with the spectral data simultaneous filtergrams in G-band, Hα 6562.8 Å, and 6118.7 Å continuum were also obtained using the UBF filter. The slope corrected spectral data was used to construct spectroheliograms, and the maps of spectral asymmetry, velocity, FWHM, Equivalent width by a Gaussian fitting of spectral line profiles for both the quiet and sunspot regions. The implications for strong and weak magnetic field locations have been discussed.

  7. Spectral researches of solar system giant planets using 2-m telescope at the Peak Terskol

    NASA Astrophysics Data System (ADS)

    Kuznyetsova, Yu.; Matsiaka, O.; Shliakhetskaya, Ya.; Krushevska, V.; Vidmachenko, A.; Andreev, M.; Sergeev, A.

    2014-03-01

    Results of observations, processing and an analysis of Uranus and Neptune spectra obtained from 2001-2012 are presented. Observations were carried out at the peak Terskol observatory (Northern Caucasus, Russia) using the coude échelle high-resolution spectrograph and the 2-meter mirror telescope Zeiss-2000. Data were obtained with spectral resolution R=45000 within 3700 - 9000 Ångstroms range. Combination of the specified equipment and spectral resolution allowed to solve the following problems: detecting of contribution of Raman scattering in planet spectra; calculating of spectral geometric albedo Ag taking into account of Raman scattering; research of long- and short-periodic variations for Ag and intensities of some chosen spectral lines; calculations of vertical structure parameters of giant planet atmospheres; search of ammonia NH3 lines in planet spectra. A comparative analysis of Uranus and Neptune spectra for different years was done.

  8. Analysis of Solar Spectral Irradiance Measurements from the SBUV/2-Series and the SSBUV Instruments

    NASA Technical Reports Server (NTRS)

    Cebula, Richard P.; DeLand, Matthew T.; Hilsenrath, Ernest

    1997-01-01

    The NOAA-9 SBEV/2 instrument has made the first regular measurements ot solar UV activity over a complete solar cycle, beginning in March 1985 and continuing as of this writing. The NOAA-9 solar irradiance data set includes the minimum between Cycles 21-22 and the current minimum at the end of Cycle 22. Although overall solar activity is low during these periods, 27-day rotational modulation is frequently present. The episode of 13-day periodicity observed during September 1994 - March 1995 shows that phenomena previously associated with high levels of solar activity can occur at any point in the solar cycle. The 205 nm irradiance and Mg II index measured by NOAA-9 showed very similar behavior during the Cycle 21-22 minimum in 1985-1986, when 27-day periodicity dominated short-term solar variations, but behaved differently in 1994-1995 during the episode of 13-day periodicity. We plan further investigations into the physical causes of this result, since it affects the extent to which the Mg II index is an accurate proxy for 205 nm irradiance variations during such episodes. The NOAA-9 Mg II data are available.

  9. 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.

  10. The SATIRE-S model and why getting solar cycle spectral irradiance trends correct is so important

    NASA Astrophysics Data System (ADS)

    Ball, William; Haigh, Joanna; Krivova, Natalie; Unruh, Yvonne; Solanki, Sami

    2014-05-01

    There is currently a wide range of potential spectral solar irradiance (SSI) solar cycle (SC) amplitudes suggested by observations and models. Therefore, SSI SC changes are still not fully understood. The magnitude of the SC flux changes has a direct impact upon the temperature and chemistry of the Earth's atmosphere. To contribute to an understanding of the solar-climate connection, it is critical that we, as the solar community, communicate effectively with the climate community, providing uncertainties in SSI data and assessments of possible SSI options. We present the SATIRE-S reconstruction in the context of these SSI datasets. SATIRE-S is a physically based, consistent SSI reconstruction over the last three solar cycles. It shows different SC spectral variability at all wavelengths compared to the NRLSSI model, widely used in climate research. Most-importantly, SC changes in the ultra-violet (UV) can be twice as large in SATIRE-S as NRLSSI. Typically NRLSSI provides a lower limit of SC SSI UV variability. SORCE satellite observations provide SC magnitudes at the upper limit of variability, exceeding that of SATIRE-S by a factor of three at some UV wavelengths. There is currently no way to be certain if any of these three SSI datasets, or others, is correct. We also present the SSI datasets in terms of their impact on stratospheric ozone, within a 2D atmospheric model, as an example of why it is important to get SC changes correct. Using NRLSSI results in the 2D atmospheric model, we see a decrease in ozone concentration at all altitudes from solar maximum to minimum. SATIRE-S and SORCE/SOLSTICE observations instead show an increase in ozone concentration in the mesosphere. The magnitude of the increase in the mesosphere when using SOLSTICE also depends greatly upon the version of the data, which means that studies using different data versions of SOLSTICE may lead to different conclusions. These results highlight why an accurate understanding of SC SSI

  11. Discovery of Peculiar Periodic Spectral Modulations in a Small Fraction of Solar-type Stars

    NASA Astrophysics Data System (ADS)

    Borra, Ermanno F.; Trottier, Eric

    2016-11-01

    A Fourier transform analysis of 2.5 million spectra in the Sloan Digital Sky Survey was carried out to detect periodic spectral modulations. Signals having the same period were found in only 234 stars overwhelmingly in the F2 to K1 spectral range. The signals cannot be caused by instrumental or data analysis effects because they are present in only a very small fraction of stars within a narrow spectral range and because signal-to-noise ratio considerations predict that the signal should mostly be detected in the brightest objects, while this is not the case. We consider several possibilities, such as rotational transitions in molecules, rapid pulsations, Fourier transform of spectral lines, and signals generated by extraterrestrial intelligence (ETI). They cannot be generated by molecules or rapid pulsations. It is highly unlikely that they come from the Fourier transform of spectral lines because too many strong lines located at nearly periodic frequencies are needed. Finally, we consider the possibility, predicted in a previous published paper, that the signals are caused by light pulses generated by ETI to makes us aware of their existence. We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis. The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the Sun is also in agreement with the ETI hypothesis. However, at this stage, this hypothesis needs to be confirmed with further work. Although unlikely, there is also a possibility that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars.

  12. Spectral response of the intrinsic region of a GaAs-InAs quantum dot solar cell considering the absorption spectra of ideal cubic dots

    NASA Astrophysics Data System (ADS)

    Biswas, Sayantan; Chatterjee, Avigyan; Biswas, Ashim Kumar; Sinha, Amitabha

    2016-10-01

    Recently, attempts have been made by some researchers to improve the efficiency of quantum dot solar cells by incorporating different types of quantum dots. In this paper, the photocurrent density has been obtained considering the absorption spectra of ideal cubic dots. The effects of quantum dot size dispersion on the spectral response of the intrinsic region of a GaAs-InAs quantum dot solar cell have been studied. The dependence of the spectral response of this region on the size of quantum dots of such solar cell has also been investigated. The investigation shows that for smaller quantum dot size dispersion, the spectral response of the intrinsic region of the cell increases significantly. It is further observed that by enlarging the quantum dot size it is possible to enhance the spectral response of such solar cells as it causes better match between absorption spectra of the quantum dots and the solar spectrum. These facts indicate the significant role of quantum dot size and size dispersion on the performance of such devices. Also, the power conversion efficiency of such solar cell has been studied under 1 sun, AM 1.5 condition.

  13. A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy of a Solar Outburst Period in 2005 and its Comparison to Solar Cycle 23 and 24 Measured Variability

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

    2015-08-01

    A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is by examining the total energy of the irradiance variation during solar outburst periods. A solar active region typically appears suddenly and then takes about seven months to decay and disperse back into the quiet Sun network. An outburst period is defined as a time when one major active region dominates the irradiance variation. The solar outburst energy, which includes the energy from all phases of active region evolution, could be considered the primary cause for irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the variation from a single active region outburst can provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (~6 months) variations from the Solar Radiation and Climate Experiment (SORCE) instruments during a solar outburst period in early 2005 are decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These fitted excess and deficit variations are then integrated over time for the energy during this outburst period, and the dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1210-1600 nm range, with all other wavelengths having in-phase variations.

  14. 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…

  15. Can we use the ozone response in a CCM to say which solar spectral irradiance is most likely correct?

    NASA Astrophysics Data System (ADS)

    Ball, William; Rozanov, Eugene; Shapiro, Anna

    2015-04-01

    Ozone plays a key role in the temperature structure of the Earth's atmosphere and absorbs damaging ultraviolet (UV) solar radiation. Evidence suggests that variations in stratospheric ozone resulting from changes in solar UV output may have an important role to play in weather over the North Atlantic and Europe on decadal timescales through a "top-down" coupling with the troposphere. However, the magnitude of the stratospheric response to the Sun over the 11-year solar cycle (SC) depends primarily on how much the UV changes. SC UV changes differ significantly between different observational instruments and the observations and models. The substantial disagreements between existing SSI datasets lead to different atmospheric responses when they are used in climate models and, therefore, we still cannot fully understand and simulate the ozone variability. We use the SOCOL chemistry-climate model, in specified dynamics mode, to calculate the atmospheric response from using different spectral irradiance from the SATIRE-S and NRLSSI models and with SORCE observations and a constant Sun. We compare the ozone and hydroxl results from these runs with observations to try to determine which SSI dataset is most likely to be correct. This is important to get a better understanding of which SSI dataset should be used in climate modelling and what magnitude of UV variability the Sun has. This will lead to a better understanding of the Sun's influence upon our climate and weather.

  16. CuO-PANI nanostructure with tunable spectral selectivity for solar selective coating application

    NASA Astrophysics Data System (ADS)

    Cindrella, L.; Prabhu., S.

    2016-08-01

    CuO-PANI nanostructure has been demonstrated as the solar selective absorber coating for the first time. The effortless chemical methods and easily scalable techniques such as precipitation, in-situ polymerization and spray coating were adopted for the fabrication of CuO nanorods and CuO-PANI nanostructures for solar application. The synthesis was carried out without using any template. The morphology and phase structure of fabricated CuO nanorods and CuO-PANI nanostructure coatings were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction analysis. The energy dispersive X-ray spectra and elemental mapping confirm the presence of the chosen elements in the nanostructure. The solar absorptance (αs), thermal emittance (εt) and selectivity (ξ) of the nanostructure coatings on glass substrate were optimized to 0.94, 0.01 and 94 respectively by changing the polyaniline content on the surface of the CuO nanorods. The efficiency of the solar selective coatings were evaluated. The optimized solar absorber coating of CuO-PANI nanostructure is highly promising for its selective optical properties.

  17. Measurements of the zenith sky intensity and spectral distribution during the solar eclipse of 12 november 1966 at bage, Brazil, and on an aircraft.

    PubMed

    Lloyd, J W; Silverman, S M

    1971-06-01

    Measurements of the zenith sky intensity and spectral distribution during the solar eclipse of 12 November 1966 at Bage, Brazil, and on an aircraft over the Atlantic are reported. These, together with measurements reported elsewhere from Santa Ines, Peru, and Quehua, Bolivia, are used to define the intensities and changes in spectral distribution during totality and to discuss the dependence of these on such factors as height and terrain.

  18. The Importance of Solar Spectral Irradiance to the Sun-Earth Connection: Lessons-learned from SORCE and Their Relevance to Future Missions

    NASA Astrophysics Data System (ADS)

    Harder, J. W.; Snow, M. A.; Richard, E. C.; Rast, M.; Merkel, A. W.; Woods, T. N.

    2014-12-01

    The Solar Radiation and Climate Experiment (SORCE) mission has provided for the first time solar spectral irradiance (SSI) observations over a full solar cycle time period with wavelength coverage from the X-ray through the near infrared. This paper will discuss the lessons-learned from SORCE including the need to develop more effective methods to track on-orbit spectroscopic response and sensitivity degradation. This is especially important in using these data products as input to modern day chemistry-climate models that require very broad spectral coverage with moderate-to-high spectral and temporal resolution to constrain the solar component to the atmospheric response. A basic requirement to obtain this essential climate record is to 1) perform preflight radiometric calibrations that are traceable SI standards along with a complete specification of the instruments spectroscopic response, and 2) design the instrument to have the ability to perform instrument-only sensitivity corrections to objectively account for on-orbit degradation. The development of the NIST SIRCUS (National Institute of Science and Technology, Sources for Irradiance and Radiance Calibration with Uniform Sources) now permits the full characterization of the spectral radiometer's response, and on-orbit degradation characterization through comparisons of redundant detectors and spectrometers appears to be the most practical method to perform these corrections for the near ultraviolet through the near infrared. Going forward, we discuss a compact spectral radiometer development that will couple with advances in CubeSat technology to allow for shorter mission lengths, relatively inexpensive development and launch costs, and reduce the risk of data gaps between successive missions without compromising measurement accuracy. We also discuss the development of a radiometric solar imager that will both greatly improve the interpretation of existing Sun-as-a-star irradiance observations and provide a

  19. Adequacy of the rigorous coupled-wave approach for thin-film silicon solar cells with periodically corrugated metallic backreflectors: spectral analysis.

    PubMed

    Shuba, Mikhail V; Faryad, Muhammad; Solano, Manuel E; Monk, Peter B; Lakhtakia, Akhlesh

    2015-07-01

    The rigorous coupled-wave approach (RCWA) is extensively used to compute optical absorption and photon absorption in thin-film photovoltaic solar cells backed by 1D metallic gratings when the wave vector of the incident light lies wholly in the grating plane. The RCWA algorithm converges rapidly for incident s-polarized light over the entire 400-1100 nm solar spectrum. It also performs well for incident p-polarized light in the 400-650 nm spectral regime, but even with a large number of Floquet harmonics in the solution, the total reflectance is underestimated in the 650-1100 nm spectral regime. Despite that shortcoming, the RCWA underestimates the solar-spectrum-integrated photon absorption rate only by 5%-10% for p-polarized light. As sunlight is almost unpolarized, the RCWA should be considered adequate to design thin-film silicon solar cells with periodically corrugated metallic backreflectors.

  20. Adequacy of the rigorous coupled-wave approach for thin-film silicon solar cells with periodically corrugated metallic backreflectors: spectral analysis.

    PubMed

    Shuba, Mikhail V; Faryad, Muhammad; Solano, Manuel E; Monk, Peter B; Lakhtakia, Akhlesh

    2015-07-01

    The rigorous coupled-wave approach (RCWA) is extensively used to compute optical absorption and photon absorption in thin-film photovoltaic solar cells backed by 1D metallic gratings when the wave vector of the incident light lies wholly in the grating plane. The RCWA algorithm converges rapidly for incident s-polarized light over the entire 400-1100 nm solar spectrum. It also performs well for incident p-polarized light in the 400-650 nm spectral regime, but even with a large number of Floquet harmonics in the solution, the total reflectance is underestimated in the 650-1100 nm spectral regime. Despite that shortcoming, the RCWA underestimates the solar-spectrum-integrated photon absorption rate only by 5%-10% for p-polarized light. As sunlight is almost unpolarized, the RCWA should be considered adequate to design thin-film silicon solar cells with periodically corrugated metallic backreflectors. PMID:26367148

  1. Spectral properties and temperature radial profiles of Saturn's main rings by Cassini-VIMS: variability with solar phase and elevation

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, F.; Ciarniello, M.; Clark, R. N.; Nicholson, P. D.; Cruikshank, D. P.; Brown, R. H.; Cuzzi, J. N.; Altobelli, N.; Spilker, L. J.; Hedman, M. M.; Dalle Ore, C. M.; Cerroni, P.

    2013-10-01

    We report about Saturn's rings average spectral properties and temperature as retrieved from ten Cassini VIMS radial mosaics acquired between october 2004 and january 2010. The dataset includes observations taken with solar phase running between 12° to 136° and elevation angle between -21° to +5°. These observations, after being reduced in spectrograms, e.g. 2D arrays containing the VIS-IR spectral (0.35-5.0 μm) and spatial (from 73.500 to 141.375 km) information, allow us a direct comparison of the derived spectral properties on a common spatial scale. Significant changes in VIS reddening, water ice abundance and grain sizes are observed across different rings radial regions. When observed at high solar phases, a remarkable increase of VIS reddening and water ice band depths is found, as a consequence of the presence of a red contaminant intimately mixed within water ice grains. Ring's particles temperature is retrieved by using the wavelength of the 3.6 μm continuum peak on reflectance spectra as a marker. For pure water ice the position of the peak, as measured in laboratory, shifts towards shorter wavelengths when temperature decreases, from about 3.65 μm at 123 K to about 3.55 μm at 88 K. When applied to VIMS rings observations, this method allow us to infer the average temperature across ring regions sampled with 400 km-wide radial bins. VIMS temperature radial profiles are compared with similar CIRS measurements acquired at the same time. We have found a substantial agreement between VIMS and CIRS results for the A and B ring while VIMS measures higher temperatures than CIRS across C ring and CD as a consequence of the lower optical depth and deviation from pure water ice composition. In summary, VIMS results show that 1) across C ring and CD the 3.6 μm peak wavelength is always higher than across B and A rings: C and CD are warmer than A and B rings; 2) when the solar elevation angle decreases to 0° (equinox) the peak's position shifts at shorter

  2. SPECTRAL SLOPE VARIATION AT PROTON SCALES FROM FAST TO SLOW SOLAR WIND

    SciTech Connect

    Bruno, R.; Trenchi, L.; Telloni, D.

    2014-09-20

    We investigated the behavior of the spectral slope of interplanetary magnetic field fluctuations at proton scales for selected high-resolution time intervals from the WIND and MESSENGER spacecraft at 1 AU and 0.56 AU, respectively. The analysis was performed within the profile of high-speed streams, moving from fast to slow wind regions. The spectral slope showed a large variability between –3.75 and –1.75 and a robust tendency for this parameter to be steeper within the trailing edge, where the speed is higher, and to be flatter within the subsequent slower wind, following a gradual transition between these two states. The value of the spectral index seems to depend firmly on the power associated with the fluctuations within the inertial range; the higher the power, the steeper the slope. Our results support previous analyses suggesting that there must be some response of the dissipation mechanism to the level of the energy transfer rate along the inertial range.

  3. The two-micron spectral characteristics of the Titanian haze derived from Cassini/VIMS solar occultation spectra

    NASA Astrophysics Data System (ADS)

    Sim, Chae Kyung; Kim, Sang Joon; Courtin, Régis; Sohn, Mirim; Lee, Dong-Hun

    2013-11-01

    Vertically-resolved spectral characteristics of the Titanian haze in the 2-μm wavelength range were derived from solar occultation spectra measured by Cassini/VIMS on January 15, 2006. At the various altitudes probed by the solar occultation measurements, we reproduced the observed spectra using a radiative transfer program including absorption by CH4 ro-vibrational bands, collision-induced absorption by N2-N2 pairs, and H2-N2 dimers, as well as absorption and scattering by the haze particles. The retrieved optical depth spectra (or τ-spectra) for the haze show marked variations in the 2.1-2.8 μm range, with peaks near 2.30 and 2.35 μm, and the relative amplitude of these peaks changing with altitude. The gross spectral shape of the τ-spectra is found similar to the typical 2-μm absorption spectra of the alkane group of hydrocarbon (CnH2n+2) ices. The τ-spectra retrieved at 2 μm and those previously retrieved at 3 μm by Kim et al. (2011) are simultaneously reproduced by combinations of 2- and 3-μm absorbance spectra of alkane ices such as CH4, C2H6, C5H12, C6H14, with the addition of a nitrile ice, CH3CN. These combinations are neither unique nor limited and need more fine-tuning to fit the detailed features of the τ-spectra. There is a need for additional laboratory measurements of absorbance and indices of refraction for a wider variety of hydrocarbon and nitrile ices in the temperature range relevant to Titan.

  4. EVIDENCE FOR THE FULL HARD X-RAY SPECTRAL SIGNATURE OF NONUNIFORM IONIZATION IN A SOLAR FLARE

    SciTech Connect

    Su Yang; Holman, Gordon D.; Dennis, Brian R. E-mail: gordon.d.holman@nasa.gov

    2011-04-20

    The hard X-ray (HXR) emission from solar flares is observed primarily from the footpoints of flare magnetic loops, where nonthermal electrons are understood to emit thick-target bremsstrahlung as they stream from the fully ionized hot corona to the denser, cooler, and partially ionized chromosphere. The change in the plasma ionization along the path of the electrons should result in a characteristic upward break and corresponding flattening of the X-ray spectrum with increasing energy at lower energies, and a downward break at higher energies. Due to the presence of thermal emission, the upward break usually cannot be observed. We report the first evidence for both breaks in spectra measured with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) during the GOES X1.2 class flare that happened on 2002 October 31. The RHESSI X-ray spectral analysis shows both the breakup at {approx}49 keV and the breakdown at {approx}134 keV at the HXR peak time. The time evolution of both breaks also agrees with the nonuniform ionization (NUI) model. Other possible explanations for the breaks are considered, but the NUI model provides the simplest explanation for the spectral shape and its time evolution. We find that the average column density of the fully ionized plasma changed from 2 x10{sup 19} cm{sup -2} in the rise phase to 7 x10{sup 21} cm{sup -2} after the peak. This indicates that plasma in the target was heated and became ionized during the flare, in agreement with heating by the nonthermal electrons and chromospheric evaporation expected in the collisional thick-target model.

  5. Experimental study of spectral and spatial distribution of solar X-rays

    NASA Technical Reports Server (NTRS)

    Acton, L. W.; Catura, R. C.; Culhane, J. L.

    1972-01-01

    The study of the physical conditions within the solar corona and the development of instrumentation and technical expertise necessary for advanced studies of solar X-ray emission are reported. Details are given on the Aerobee-borne-X-ray spectrometer/monochromator and also on the observing program. Preliminary discussions of some results are presented and include studies of helium-like line emission, mapping O(VII) and Ne(IX) lines, survey of O(VII) and Ne(IX) lines, study of plage regions and small flares, and analysis of line emission from individual active regions. It is concluded that the use of large-area collimated Bragg spectrometers to scan narrow wavelength intervals and the capability of the SPARCS pointing control to execute a complex observing program are established.

  6. Vegetation Red-edge Spectral Modeling for Solar-induced Chlorophyll Fluorescence Retrieval at O2-B Band

    NASA Astrophysics Data System (ADS)

    Huang, C.; Zhang, L.; Qiao, N.; Zhang, X.; Li, Y.

    2015-12-01

    Remotely sensed solar-induced chlorophyll fluorescence (SIF) has been considered an ideal probe in monitoring global vegetation photosynthesis. However, challenges in accurate estimate of faint SIF (less than 5% of the total reflected radiation in near infrared bands) from the observed apparent reflected radiation greatly limit its wide applications. Currently, the telluric O2-B (~688nm) and O2-A (~761nm) have been proved to be capable of SIF retrieval based on Fraunhofer line depth (FLD) principle. They may still work well even using conventional ground-based commercial spectrometers with typical spectral resolutions of 2~5 nm and high enough signal-to-noise ratio (e.g., the ASD spectrometer). Nevertheless, almost all current FLD based algorithms were mainly developed for O2-A, a few concentrating on the other SIF emission peak in O2-B. One of the critical reasons is that it is very difficult to model the sudden varying reflectance around O2-B band located in the red-edge spectral region (about 680-800 nm). This study investigates a new method by combining the established inverted Gaussian reflectance model (IGM) and FLD principle using diurnal canopy spectra with relative low spectral resolutions of 1 nm (FluorMOD simulations) and 3 nm (measured by ASD spectrometer) respectively. The IGM has been reported to be an objective and good method to characterize the entire vegetation red-edge reflectance. Consequently, the proposed SIF retrieval method (hereinafter called IGMFLD) could exploit all the spectral information along the whole red-edge (680-800 nm) to obtain more reasonable reflectance and fluorescence correction coefficients than traditional FLD methods such as the iFLD. Initial results show that the IGMFLD can better capture the spectrally non-linear characterization of the reflectance in 680-800 nm and thereby yields much more accurate SIFs in O2-B than typical FLD methods, including sFLD, 3FLD and iFLD (see figure 1). Finally, uncertainties and prospect

  7. Assessment of performances of sun zenith angle and altitude parameterisations of atmospheric radiative transfer for spectral surface downwelling solar irradiance

    NASA Astrophysics Data System (ADS)

    Wald, L.; Blanc, Ph.

    2010-09-01

    Satellite-derived assessments of surface downwelling solar irradiance are more and more used by engineering companies in solar energy. Performances are judged satisfactory for the time being. Nevertheless, requests for more accuracy are increasing, in particular in the spectral definition and in the decomposition of the global radiation into direct and diffuse radiations. One approach to reach this goal is to improve both the modelling of the radiative transfer and the quality of the inputs describing the optical state. Within their joint project Heliosat-4, DLR and MINES ParisTech have adopted this approach to create advanced databases of solar irradiance succeeding to the current ones HelioClim and SolEMi. Regarding the model, we have opted for libRadtran, a well-known model of proven quality. As many similar models, running libRadtran is very time-consuming when it comes to process millions or more pixels or grid cells. This is incompatible with real-time operational process. One may adopt the abacus approach, or look-up tables, to overcome the problem. The model is run for a limited number of cases, covering the whole range of values taken by the various inputs of the model. Abaci are such constructed. For each real case, the irradiance value is computed by interpolating within the abaci. In this way, real-time can be envisioned. Nevertheless, the computation of the abaci themselves requires large computing capabilities. In addition, searching the abaci to find the values to interpolate can be time-consuming as the abaci are very large: several millions of values in total. Moreover, it raises the extrapolation problem of parameter out-of-range during the utilisation of the abaci. Parameterisation, when possible, is a means to reduce the amount of computations to be made and subsequently, the computation effort to create the abaci, the size of the abaci, the extrapolation and the searching time. It describes in analytical manner and with a few parameters the

  8. Middle Atmosphere Response to Different Descriptions of the 11-Year Solar Cycle in Spectral Irradiance in a Chemistry-Climate Model

    NASA Technical Reports Server (NTRS)

    Swartz, W. H.; Stolarski, R. S.; Oman, L. D.; Fleming, E. L.; Jackman, C. H.

    2012-01-01

    The 11-year solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response 50 using the SORCE SSI is nearly 2 K per 100 units 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the

  9. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    NASA Astrophysics Data System (ADS)

    Swartz, W. H.; Stolarski, R. S.; Oman, L. D.; Fleming, E. L.; Jackman, C. H.

    2012-03-01

    The 11-yr solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 - 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the

  10. The role of the spectral sensitivity curve in the selection of relevant biological dosimeters for solar UV monitoring.

    PubMed

    Modos, K; Gaspar, S; Kerekgyarto, T; Vink, A A; Roza, L; Fekete, A

    1999-01-01

    To estimate the risk of enhanced UV-B radiation due to stratospheric ozone depletion, phage T7 and uracil thin-layer biological dosimeters have been developed, which weight the UV irradiance according to induced DNA damage. To study the molecular basis of the biological effects observed after UV irradiation, the spectral sensitivity curves of the two dosimeters and induction of the two major DNA photoproducts, cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts ((6-4)PDs), in phage T7 have been determined for polychromatic UV sources. CPDs and (6-4)PDs are determined by lesion-specific monoclonal antibodies in an immunodotblot assay. Phage T7 and uracil biological dosimeters together with a Robertson-Berger (RB) meter have been used for monitoring environmental radiation from the polar region to the equator. The biologically effective dose (BED) established with the three different dosimeters increases according to the changes in the solar angle and ozone column, but the degree of the change differs significantly. The results can be explained based on the different spectral sensitivities of the dosimeters. A possible method for determining the trend of the increase in the biological risk due to ozone depletion is suggested.

  11. 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 ...

  12. Effects of High Ion Temperatures on Spectral Line Diagnostics in the Source Region of the High-speed Solar Wind

    NASA Astrophysics Data System (ADS)

    Brickhouse, N. S.; Esser, R.

    1997-04-01

    Theoretical work on solar wind acceleration has suggested that the proton and electron temperatures at the base of the solar coronal hole region are not thermally equilibrated but that instead the proton temperature may exceed the electron temperature significantly. Recently, Kohl, Strachan, & Gardner have measured both broad and narrow components of the H Lyα profile and have suggested that the broad component may be the signature of high proton temperatures, ~4-6 × 106 K or more. Since proton impact excitation can contribute to the emission line excitation processes, high proton temperatures have important implications for some spectral line emissivities that are useful for electron temperature and density determinations. The diagnostics most affected are those which are sensitive to the distribution of population within the fine structure of the ground state configuration. We discuss selected case studies. For modest proton temperatures (Tp = 3Te) we have found effects on temperature diagnostics to be less than 30% but effects on some density diagnostics may be as large as 1 order of magnitude.

  13. First evidence of non-Gaussian solar flare EUV spectral line profiles and accelerated non-thermal ion motion

    NASA Astrophysics Data System (ADS)

    Jeffrey, Natasha L. S.; Fletcher, Lyndsay; Labrosse, Nicolas

    2016-05-01

    Context. The properties of solar flare plasma can be determined from the observation of optically thin lines. The emitting ion distribution determines the shape of the spectral line profile, with an isothermal Maxwellian ion distribution producing a Gaussian profile. Non-Gaussian line profiles may indicate more complex ion distributions. Aims: We investigate the possibility of determining flare-accelerated non-thermal ion and/or plasma velocity distributions. Methods: We study EUV spectral lines produced during a flare SOL2013-05-15T01:45 using the Hinode EUV Imaging Spectrometer (EIS). The flare is located close to the eastern solar limb with an extended loop structure, allowing the different flare features: ribbons, hard X-ray (HXR) footpoints and the loop-top source to be clearly observed in UV, EUV and X-rays. EUV line spectroscopy is performed in seven different regions covering the flare. We study the line profiles of the isolated and unblended Fe XVI lines (λ262.9760 Å ) mainly formed at temperatures of ~2 to 4 MK. Suitable Fe XVI line profiles at one time close to the peak soft X-ray emission and free of directed mass motions are examined using: 1. a higher moments analysis, 2. Gaussian fitting, and 3. by fitting a kappa distribution line profile convolved with a Gaussian to account for the EIS instrumental profile. Results: Fe XVI line profiles in the flaring loop-top, HXR footpoint and ribbon regions can be confidently fitted with a kappa line profile with an extra variable κ, giving low, non-thermal κ values between 2 and 3.3. An independent higher moments analysis also finds that many of the spectral line kurtosis values are higher than the Gaussian value of 3, even with the presence of a broad Gaussian instrumental profile. Conclusions: A flare-accelerated non-thermal ion population could account for both the observed non-Gaussian line profiles, and for the Fe XVI "excess" broadening found from Gaussian fitting, if the emitting ions are interacting

  14. Solar monochromatic images in magneto-sensitive spectral lines and maps of vector magnetic fields

    NASA Technical Reports Server (NTRS)

    Shihui, Y.; Jiehai, J.; Minhan, J.

    1985-01-01

    A new method which allows by use of the monochromatic images in some magneto-sensitive spectra line to derive both the magnetic field strength as well as the angle between magnetic field lines and line of sight for various places in solar active regions is described. In this way two dimensional maps of vector magnetic fields may be constructed. This method was applied to some observational material and reasonable results were obtained. In addition, a project for constructing the three dimensional maps of vector magnetic fields was worked out.

  15. Nanocomposite Architecture for Rapid, Spectrally-Selective Electrochromic Modulation of Solar Transmittance.

    PubMed

    Kim, Jongwook; Ong, Gary K; Wang, Yang; LeBlanc, Gabriel; Williams, Teresa E; Mattox, Tracy M; Helms, Brett A; Milliron, Delia J

    2015-08-12

    Two active electrochromic materials, vacancy-doped tungsten oxide (WO(3-x)) nanocrystals and amorphous niobium oxide (NbOx) glass are arranged into a mesostructured architecture. In a strategy applicable across electrochemical applications, the critical dimensions and interfacial connections in the nanocomposite are designed to optimize pathways for electrochemical charging and discharging. The result is an unprecedented optical range for modulation of visible and near-infrared solar radiation with rapid switching kinetics that indicate the WO(3-x) nanocrystal framework effectively pumps charge out of the normally sluggish NbOx glass. The material is durable for at least 2000 electrochemical cycles. PMID:26189324

  16. A formula for calculating theoretical photoelectron fluxes resulting from the He/+/ 304 A solar spectral line

    NASA Technical Reports Server (NTRS)

    Richards, P. G.; Torr, D. G.

    1981-01-01

    A simplified method for the evaluation of theoretical photoelectron fluxes in the upper atmosphere resulting from the solar radiation at 304 A is presented. The calculation is based on considerations of primary and cascade (secondary) photoelectron production in the two-stream model, where photoelectron transport is described by two electron streams, one moving up and one moving down, and of loss rates due to collisions with neutral gases and thermal electrons. The calculation is illustrated for the case of photoelectrons at an energy of 24.5 eV, and it is noted that the 24.5-eV photoelectron flux may be used to monitor variations in the solar 304 A flux. Theoretical calculations based on various ionization and excitation cross sections of Banks et al. (1974) are shown to be in generally good agreement with AE-E measurements taken between 200 and 235 km, however the use of more recent, larger cross sections leads to photoelectron values a factor of two smaller than observations but in agreement with previous calculations. It is concluded that a final resolution of the photoelectron problem may depend on a reevaluation of the inelastic electron collision cross sections.

  17. ON THE SPECTRAL HARDENING AT {approx}>300 keV IN SOLAR FLARES

    SciTech Connect

    Li, G.; Kong, X.; Zank, G.; Chen, Y.

    2013-05-20

    It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies {approx}>300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range {approx}k {sup -2.7}. A {approx}k {sup -2.7} dissipation range spectrum is consistent with recent solar wind observations.

  18. Light trapping efficiency comparison of Si solar cell textures using spectral photoluminescence.

    PubMed

    Barugkin, Chog; Allen, Thomas; Chong, Teck K; White, Thomas P; Weber, Klaus J; Catchpole, Kylie R

    2015-04-01

    The band-to-band absorption enhancement due to various types of light trapping structures is studied experimentally with photoluminescence (PL) on monocrystalline silicon wafers. Four basic light trapping structures are examined: reactive ion etched texture (RIE), metal-assisted etched texture (MET), random pyramid texture (RAN) and plasmonic Ag nanoparticles with a diffusive reflector (Ag/DR). We also compare two novel combined structures of front side RIE/rear side RAN and front side RIE/rear side Ag/DR. The use of photoluminescence allows us to measure the absorption due to band-to-band transitions only, and excludes parasitic absorption from free carriers and other sources. The measured absorptance spectra are used to calculate the maximum generation current for each structure, and the light trapping efficiency is compared to a recently-proposed figure of merit. The results show that by combining RIE with RAN and Ag/DR, we can fabricate two structures with excellent light trapping efficiencies of 55% and 52% respectively, which is well above previously reported values for similar wafer thicknesses. A comparison of the measured band-band absorption and the EQE of back-contact silicon solar cells demonstrates that PL extracted absorption provides a very good indication of long wavelength performance for high efficiency silicon solar cells. PMID:25968804

  19. An intense NIR emission from Ca14Al10Zn6O35:Mn(4+),Yb(3+)via energy transfer for solar spectral converters.

    PubMed

    Lü, Wei; Jiao, Mengmeng; Shao, Baiqi; Zhao, Lingfei; Feng, Yang; You, Hongpeng

    2016-01-14

    To date, most current reports on the development and optimization of solar spectral converters have described the utilization of energy transfer among rare-earth ions. Here, we introduce non-rare-earth ion Mn(4+) to transfer energy to Yb(3+), which can exhibit strong near-infrared luminescence. It can harvest UV-blue photons and exhibits intense NIR emission of Yb(3+) around 1000 nm, perfectly matching the maximum spectral response of Si solar cells. It demonstrates for the first time that efficient energy transfer occurs with a decrease in the excited state lifetime and red photoluminescence (PL) from Mn(4+) with increasing Yb(3+) concentration. These results demonstrate that the Mn(4+) ions can be an efficient and direct sensitizer harvesting UV-blue photons. It could provide new avenues for developing harvesting Si-based solar cells.

  20. Spectral properties of the extreme solar system objects 2012 DR30 and 2013 AZ60

    NASA Astrophysics Data System (ADS)

    Szabo, G.; Kiss, Cs.; Duffard, R.; Pinilla-Alonso, N.; Licandro, J.

    2014-04-01

    2012 DR30 and 2013 AZ60 represent two examples of TNOs with very large aphelion distances (2405 and 1951 AU, respectively), thus standing for the currently best candidates of possible scattered-in Oort-cloud objects. Though they possibly shared a similar dynamical scenario, the two bodies exhibit surprisingly diverging prediction for orbital evolution and also quite different surface properties (Kiss et al. 2013, Kiss et al. 2014). Here we compare these optical and infrared photometry and spectra of the two bodies. Both show a generaly flat spectrum, but with significantly differing slope. We find clear signs of water ice on 2013 DR30 particulary, which is an exciting diagnostic of a possible water reservoir at very large perihelion distances, and on the other hand, suggests a close link between the giant cometary nuclei of the Oort Cloud (for that Hale-Bopp is the only known example in our Solar System) and these exotic TNOs.

  1. Spectral and Imaging Observations of a White-light Solar Flare in the Mid-infrared

    NASA Astrophysics Data System (ADS)

    Penn, Matt; Krucker, Säm; Hudson, Hugh; Jhabvala, Murzy; Jennings, Don; Lunsford, Allen; Kaufmann, Pierre

    2016-03-01

    We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17:50 (C7.0), using Quantum Well Infrared Photodetector cameras at an auxiliary of the McMath-Pierce telescope. The flare emissions, the first simultaneous observations in two mid-infrared bands at 5.2 and 8.2 μ {{m}} with white-light and hard X-ray coverage, revealed impulsive time variability with increases on timescales of ˜4 s followed by exponential decay at ˜10 s in two bright regions separated by about 13\\prime\\prime . The brightest source is compact, unresolved spatially at the diffraction limit (1\\_\\_AMP\\_\\_farcs;72 at 5.2 μ {{m}}). We identify the IR sources as flare ribbons also seen in white-light emission at 6173 Å observed by SDO/HMI, with twin hard X-ray sources observed by Reuven Ramaty High Energy Solar Spectroscopic Imager, and with EUV sources (e.g., 94 Å) observed by SDO/AIA. The two infrared points have nearly the same flux density (fν, W m-2 Hz) and extrapolate to a level of about an order of magnitude below that observed in the visible band by HMI, but with a flux of more than two orders of magnitude above the free-free continuum from the hot (˜15 MK) coronal flare loop observed in the X-ray range. The observations suggest that the IR emission is optically thin; this constraint and others suggest major contributions from a density less than about 4× {10}13 cm-3. We tentatively interpret this emission mechanism as predominantly free-free emission in a highly ionized but cool and rather dense chromospheric region.

  2. NIMBUS-7 SBUV (Solar Backscatter Ultraviolet) observations of solar UV spectral irradiance variations caused by solar rotation and active-region evolution for the period November 7, 1978 - November 1, 1980

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Repoff, T. P.; Donnelly, R. F.

    1984-01-01

    Observations of temporal variations of the solar UV spectral irradiance over several days to a few weeks in the 160-400 nm wavelength range are presented. Larger 28-day variations and a second episode of 13-day variations occurred during the second year of measurements. The thirteen day periodicity is not a harmonic of the 28-day periodicity. The 13-day periodicity dominates certain episodes of solar activity while others are dominated by 28-day periods accompanied by a week 14-day harmonic. Techniques for removing noise and long-term trends are described. Time series analysis results are presented for the Si II lines near 182 nm, the Al I continuum in the 190 nm to 205 nm range, the Mg I continuum in the 210 nm to 250 nm range, the MgII H & K lines at 280 nm, the Mg I line at 285 nm, and the Ca II K & H lines at 393 and 397 nm.

  3. Measuring the Spectral Expression of Carbon Dioxide in the Solar Reflected Spectrum with AVIRIS

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    2001-01-01

    Carbon dioxide is a low-concentration, but important, component of the Earth's atmosphere. This gas absorbs electromagnetic radiation (EMR) in several regions of the spectrum. Absorption of energy by carbon dioxide adds heat to the atmosphere. In the world today, the burning of fossil fuels and other anthropogenic processes adds carbon dioxide to the atmosphere. Other natural processes in the Earth's system both add and remove carbon dioxide. Overall, measurements of atmospheric carbon dioxide at selected sites around the globe show an increased carbon dioxide concentration in the atmosphere. A figure shows the measured carbon dioxide from Mauna Loa, Hawaii, from 1958 to 2000. Overall, the concentration has increased from 315 to 365 ppm at this site over this period. (There is also a yearly cycle to the concentration that is timed with and hypothesized to be related to the vegetation growing season in the Northern Hemisphere.) The overall expected effect of this increase of atmospheric carbon dioxide is trapping of heat in the atmosphere and global warming. While this overall relationship between carbon dioxide and global warming seems straightforward, many of the specific details relating to regional and local sources and sinks and gradients of carbon dioxide are not well understood. A remote sensing capability to measure carbon dioxide could provide important inputs for scientific research to better understand the distribution and change in atmospheric carbon dioxide at detailed spatial and temporal levels. In pursuit of this remote sensing of carbon dioxide objective, this paper analyzes the expression of carbon dioxide in the spectral range measured by the Airborne Visible/Infrared Imagery Spectrometer (AVIRIS). Based on these analyses, a spectral-fitting algorithm that uses AVIRIS measured spectra and MODTRAN radiative-transfer code modeled spectra to derive total column carbon dioxide abundance has been developed. This algorithm has been applied to an AVIRIS

  4. Absolute intensity measurements of CO2 bands in the 2395-2680/cm region

    NASA Technical Reports Server (NTRS)

    Malathy Devi, V.; Benner, D. C.; Rinsland, C. P.

    1984-01-01

    Absolute intensities for over 800 transitions belonging to twelve bands of (C-12)(O-16)2, (O-16)(C-12)(O-18), (O-16)(C-12)(O-17), and (O-16)(C-13)(O-18) molecules in the 2395-2680/cm spectral region have been derived using a nonlinear least-squares spectral fitting procedure. The data used in the analysis were recorded at room temperature and low pressure with the 0.01/cm resolution Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory. The measured intensities obtained for each band have been analyzed to derive the vibrational band intensity and F-factor coefficients. The results are compared with other published values.

  5. Measurements of absolute line intensities in carbon dioxide bands near 5.2 microns

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Benner, D. C.; Devi, V. M.

    1985-01-01

    A nonlinear least-squares spectral fitting procedure has been used to derive experimental absolute intensities for over 300 unblended lines belonging to twelve CO2 bands in the 5.2-micron region. The spectral data were recorded at 0.01/cm resolution and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory on Kitt Peak and have a signal-to-rms noise ratio of 2000-4000. A natural sample of carbon dioxide was used as the sample gas. For each band, the measured line intensities have been analyzed to derive the vibrational band intensity and coefficients of the F factor. The results are compared to the values used to calculate the intensities in the 1982 Air Force Geophysics Laboratory line parameters compilation.

  6. 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.

  7. Spectral response of the solar atmosphere to an X-class flare event

    NASA Astrophysics Data System (ADS)

    Lacatus, Daniela Adriana; Donea, Alina

    2016-05-01

    The only X-class flare of 2015 observed by IRIS occurred at 16:22 UT on 11 March 2015, in AR 12297. This flare generated significant seismic transients in the photosphere at the eastern location of the flare. IRIS observations of the chromosphere and transition region help us understand the physics of the sunquake. In this work we will analyse this event using data from IRIS, SDO, and RHESSI. The IRIS rasters scanned the area between the main footpoints of the solar flare, and a wealth of chromospheric information has been inferred about the dynamics of the event. The main X-ray emission dominates the eastern flare footpoint, being missed by the IRIS slit. Significant enhancements in the chromospheric and TR lines intensities were identified. The forbidden line of Fe XXI 1354.1 Å is detected after the flare peak revealing the coronal responses to the flare. Plasma downflows of up to 300 km/s were identified in the majority of the observed lines, consistent with magnetic field local reconfiguration. We have also analysed an erupting filament developing at an earlier time, which moved rapidly towards the eastern part of the active region. We discuss the possibility that this filament might have pre-conditioned the chromosphere for the flare process.

  8. Exposure to non-extreme solar UV daylight: spectral characterization, effects on skin and photoprotection.

    PubMed

    Marionnet, Claire; Tricaud, Caroline; Bernerd, Françoise

    2014-12-23

    The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320-400 nm and UVB, 280-320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky) can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1) the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2) description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3) analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure.

  9. The temperature of solar flares determined from X-ray spectral line ratios

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Feldman, U.

    1987-01-01

    The effect on derived solar flare plasma temperatures of (1) a power-law distribution of emission measure as a function of temperature, (2) a high-temperature isothermal source coupled to a low-temperature power-law distribution of emission measure, and (3) two isothermal sources is calculated for line ratios involving the ions S XV, Ca XIX, Ca XX, Fe XXV, Ni XXVII, and Fe XXVI. It is shown that if the Fe XXV temperature is less than about 25 million K, as is true for the majority of flares, then about 75 percent or more of the emission measure is produced by plasma at temperatures equal to or less than the Fe XXV temperature plus about 3 million K. If the Fe XXV temperature is 20 million K or higher, this percentage can be larger. This result is obtained even if a superhot component exists that extends up to several hundred million degrees. Temperatures determined from Fe XXVI demonstrate the presence of a superhot component.

  10. Ion-scale spectral break of solar wind turbulence at high and low beta

    PubMed Central

    Chen, C H K; Leung, L; Boldyrev, S; Maruca, B A; Bale, S D

    2014-01-01

    The power spectrum of magnetic fluctuations in the solar wind at 1 AU displays a break between two power laws in the range of spacecraft-frame frequencies 0.1 to 1 Hz. These frequencies correspond to spatial scales in the plasma frame near the proton gyroradius ρi and proton inertial length di. At 1 AU it is difficult to determine which of these is associated with the break, since and the perpendicular ion plasma beta is typically β⊥i∼1. To address this, several exceptional intervals with β⊥i≪1 and β⊥i≫1 were investigated, during which these scales were well separated. It was found that for β⊥i≪1 the break occurs at di and for β⊥i≫1 at ρi, i.e., the larger of the two scales. Possible explanations for these results are discussed, including Alfvén wave dispersion, damping, and current sheets. PMID:26074642

  11. Exposure to Non-Extreme Solar UV Daylight: Spectral Characterization, Effects on Skin and Photoprotection

    PubMed Central

    Marionnet, Claire; Tricaud, Caroline; Bernerd, Françoise

    2014-01-01

    The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320–400 nm and UVB, 280–320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky) can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1) the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2) description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3) analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure. PMID:25546388

  12. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    NASA Astrophysics Data System (ADS)

    Swartz, W. H.; Stolarski, R. S.; Oman, L. D.; Fleming, E. L.; Jackman, C. H.

    2012-07-01

    The 11-yr solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOSCCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 - 3 times larger than the simulation using the NRL SSI. The GEOSCCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. This is important in that it means that chemistry-transport models should simulate the solar cycle in ozone well, while general circulation models without coupled chemistry will underestimate the temperature response to the solar cycle significantly in the middle atmosphere. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally

  13. Spectral properties of plant leaves pertaining to urban landscape design of broad-spectrum solar ultraviolet radiation reduction.

    PubMed

    Yoshimura, Haruka; Zhu, Hui; Wu, Yunying; Ma, Ruijun

    2010-03-01

    Human exposure to harmful ultraviolet (UV) radiation has important public health implications. Actual human exposure to solar UV radiation depends on ambient UV irradiance, and the latter is influenced by ground reflection. In urban areas with higher reflectivity, UV exposure occurs routinely. To discover the solar UV radiation regulation mechanism of vegetation, the spectral reflectance and transmittance of plant leaves were measured with a spectrophotometer. Typically, higher plants have low leaf reflectance (around 5%) and essentially zero transmittance throughout the UV region regardless of plant species and seasonal change. Accordingly, incident UV radiation decreases to 5% by being reflected and is reduced to zero by passing through a leaf. Therefore, stratified structures of vegetation are working as another terminator of UV rays, protecting whole terrestrial ecosystems, while vegetation at waterfronts contributes to protect aquatic ecosystems. It is possible to protect the human population from harmful UV radiation by urban landscape design of tree shade and the botanical environment. Even thin but uniformly distributed canopy is effective in attenuating UV radiation. To intercept diffuse radiation, UV screening by vertical structures such as hedges should be considered. Reflectivity of vegetation is around 2%, as foliage surfaces reduce incident UV radiation via reflection, while also eliminating it by transmittance. Accordingly, vegetation reduces incident UV radiation to around 2% by reflection. Vegetation influence on ambient UV radiation is broad-spectrum throughout the UV region. Only trees provide cool UV protective shade. Urban landscapes aimed at abating urban heat islands integrated with a reduction of human UV over-exposure would contribute to mitigation of climate change.

  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. Wavelet analysis of the singular spectral reconstructed time series to study the imprints of solar-ENSO-geomagnetic activity on Indian climate

    NASA Astrophysics Data System (ADS)

    Lakshmi Sunkara, Sri; Krishna Tiwari, Rama

    2016-09-01

    To study the imprints of the solar-ENSO-geomagnetic activity on the Indian subcontinent, we have applied singular spectral analysis (SSA) and wavelet analysis to the tree-ring temperature variability record from the Western Himalayas. Other data used in the present study are the solar sunspot number (SSN), geomagnetic indices (aa index), and the Southern Oscillation Index (SOI) for the common time period of 1876-2000. Both SSA and wavelet spectral analyses reveal the presence of 5-7-year short-term ENSO variations and the 11-year solar cycle, indicating the possible combined influences of solar-geomagnetic activities and ENSO on the Indian temperature. Another prominent signal corresponding to 33-year periodicity in the tree-ring record suggests the Sun-temperature variability link probably induced by changes in the basic state of the Earth's atmosphere. In order to complement the above findings, we performed a wavelet analysis of SSA reconstructed time series, which agrees well with our earlier results and increases the signal-to-noise ratio, thereby showing the strong influence of solar-geomagnetic activity and ENSO throughout the entire period. The solar flares are considered responsible for causing the atmospheric circulation patterns. The net effect of solar-geomagnetic processes on the temperature record might suggest counteracting influences on shorter (about 5-6-year) and longer (about 11-12-year) timescales. The present analyses suggest that the influence of solar activities on the Indian temperature variability operates in part indirectly through coupling of ENSO on multilateral timescales. The analyses, hence, provide credible evidence of teleconnections of tropical Pacific climatic variability and Indian climate ranging from inter-annual to decadal timescales and also suggest the possible role of exogenic triggering in reorganizing the global Earth-ocean-atmospheric systems.

  17. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

    PubMed

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-12-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

  18. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties

    NASA Astrophysics Data System (ADS)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-01-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

  19. Exploration of the solar-stellar connection at high spectral resolution with the Ultraviolet Spectrometer and Polarimeter, and studies of thermal bifurcation at the photosphere-chromosphere interface

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The dynamics of high-excitation plasma in the 100,000 K transition zones of stars of late spectral type, as observed with the International Ultraviolet Explorer, was compared with the radial gas velocities of individual structural features of the solar TZ, as observed with high spatial resolution by the UVSP on the Solar Maximum Mission. The 4th-positive system of carbon monoxide in the quiet sun and in active regions was studied in order to explore the properties of thermal inhomogeneities at the critical interface between the photosphere and chromosphere.

  20. Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

  1. Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations

    NASA Astrophysics Data System (ADS)

    Yeo, K. L.; Krivova, N. A.; Solanki, S. K.; Glassmeier, K. H.

    2014-10-01

    Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. Aims: We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI. Methods: SATIRE-S ascribes variation in solar irradiance on timescales greater than a day to photospheric magnetism. The solar spectrum is reconstructed from the apparent surface coverage of bright magnetic features and sunspots in the daily data using the modelled intensity spectra of these magnetic structures. We cross-calibrated the various data sets, harmonizing the model input so as to yield a single consistent time series as the output. Results: The model replicates 92% (R2 = 0.916) of the variability in the PMOD TSI composite including the secular decline between the 1996 and 2008 solar cycle minima. The model also reproduces most of the variability in observed Lyman-α irradiance and the Mg II index. The ultraviolet solar irradiance measurements from the UARS and SORCE missions are mutually consistent up to about 180 nm before they start to exhibit discrepant rotational and cyclical variability, indicative of unresolved instrumental effects. As a result, the agreement between model and measurement, while relatively good below 180 nm, starts to deteriorate above this wavelength. As with earlier similar investigations, the reconstruction cannot reproduce the overall trends in SORCE/SIM SSI. We argue, from the lack of clear solar cycle modulation in the SIM record and the inconsistency between the total flux recorded by the instrument and TSI, that unaccounted instrumental trends are present. Conclusions: The daily solar irradiance time series is consistent with observations from multiple sources, demonstrating its validity and utility for climate models. It also provides further evidence that photospheric magnetism is the prime driver of

  2. Absolute Radiometric Calibration Of The Thematic Mapper

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.; Moran, M. S.; Palmer, J. M.; Yuan, B.

    1986-11-01

    The results are presented of five in-flight absolute radiometric calibrations, made in the period July 1984 to November 1985, at White Sands, New Mexico, of the solar reflective bands of the Landsat-5 Thematic Mapper (TM) . The 23 bandcalibrations made on the five dates show a ± 2.8% RMS variation from the mean as a percentage of the mean.

  3. Relative ultraviolet spectral intensity of direct solar radiation, sky radiation and surface reflections. Relative contribution of natural sources to the outdoor UV irradiation of man.

    PubMed

    Kromann, N; Wulf, H C; Eriksen, P; Brodthagen, H

    1986-04-01

    Relative measurements of UVA and UVB radiation from the sun and the sky, as well as the reflected intensity from various land and water surfaces, have been carried out in the Copenhagen area. The measurements were taken in January and in the period April through July and supplemented by measurements in Greenland during May. Likewise, the angular distribution of direct solar radiation and sky radiation close to the direction of the sun was measured with a 0.5 degree field of view. Absolute UV irradiances were measured with detector-filter combinations. Calculations of the relative contributions of direct solar radiation, sky radiation and reflected radiation to the irradiation of a standing person show, in particular, that if seawater with waves is the surrounding scene, its reflected radiation will account for more than 10% of the received UV dose.

  4. Temporal Evolution of Spectral and Angular Characteristics of SEP Particles during Several GLEs of Solar Cycle 23 Derived from NM Data

    NASA Astrophysics Data System (ADS)

    Mishev, Alexander; Usoskin, Ilya; Kocharov, Leon

    High-energy charged particles of solar origin could represent a severe radiation risk for astronauts and air crew. In addition, they could disrupt technological systems. When a ground-based neutron monitor register abrupt increases in solar energetic particles (SEPs), we observe a special case of solar energetic particle event, a ground-level enhancement (GLE). In order to derive the spectral and angular characteristics of GLE particles a precise computation of solar energetic particle propagation in the Earth's magnetosphere and atmosphere is necessary. It consists of detailed computation of assymptotic cones for neutron monitors (NMs) and application of inverse method using the newly computed neutron monitor yield function. Assymptotic directions are computed using the Planetocosmics code and realistic magnetospheric models, namely IGRF as the internal model and Tsyganenko 89 with the corresponding Kp index as the external one. The inverse problem solution is performed on the basis of non-linear least squares method, namely Levenberg-Marqurdt. In the study presented here, we analyse several major GLEs of the solar cycle 23 as well as the first GLE event of the solar cycle 24, namely GLE69, GLE70 and GLE 71. The SEP spectra and pitch angle distribution are obtained at different momenta since the event's onset. The obtained characteristics are compared with previously reported results. The obtained results are briefly discussed.

  5. Core and Wing Densities of Asymmetric Coronal Spectral Profiles: Implications for the Mass Supply of the Solar Corona

    NASA Technical Reports Server (NTRS)

    Patsourakos, S.; Klimchuk, J. A.; Young, P. R.

    2014-01-01

    Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding approximately equal to 50 km per sec. Here, we perform a study of the density of the rapidly upflowing material and compare it with that of the line core that corresponds to the bulk of the plasma. For this task, we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe(sub XIV) lines at 264.78 and 274.20 Angstroms is used to determine wing and core densities.We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe(sub XIV) lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.

  6. Core and wing densities of asymmetric coronal spectral profiles: Implications for the mass supply of the solar corona

    SciTech Connect

    Patsourakos, S.; Klimchuk, J. A.; Young, P. R. E-mail: james.a.klimchuk@nasa.gov

    2014-02-01

    Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding ≈50 km s{sup –1}. Here, we perform a study of the density of the rapidly upflowing material and compare it with that of the line core that corresponds to the bulk of the plasma. For this task, we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe XIV lines at 264.78 and 274.20 Å is used to determine wing and core densities. We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe XIV lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.

  7. Preliminary experiment requirements document for Solar and Terrestrial Atmospheres Spectrometer (STAS)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The principal scientific objective of the Solar and Terrestrial Atmospheres Spectrometer (STAS) project is the measurement of the absolute ultraviolet solar spectral irradiance with: (1) resolution of better than 15 mA, and (2) absolute irradiance uncertainty at the state of the art (less than or equal to 3%). High measurement accuracy coupled with high spectral resolution are necessary to identify the nature of the radiation, its variability, and to identify solar processes which may cause the changes. Solar radiation between 1200 and 3600 A dominates the photochemistry of the mesosphere and stratosphere. Some important minor species, such as NO, show very complex and fundamentally narrow structure in their photodestruction cross sections, especially in the region of the Schumann-Runge bands of O2. Understanding the photochemical processes in the terrestrial atmosphere requires knowledge of both the cross sections and of the solar spectrum with the highest possible resolution and accuracy.

  8. 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

  9. 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.

  10. Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors

    NASA Technical Reports Server (NTRS)

    Deland, Matthew T.; Cebula, Richard P.

    1994-01-01

    Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

  11. Wavelet analysis of the singular spectral reconstructed time series to study the imprints of Solar-ENSO-Geomagnetic activity on Indian climate

    NASA Astrophysics Data System (ADS)

    Sri Lakshmi, S.; Tiwari, R. K.

    2015-09-01

    In order to study the imprints of solar-ENSO-geomagnetic activity on the Indian Subcontinent, we have applied the Singular Spectral Analysis (SSA) and wavelet analysis to the tree ring temperature variability record from the western Himalayas. The data used in the present study are the Solar Sunspot Number (SSN), Geomagnetic Indices (aa Index), Southern Oscillation Index (SOI) and tree ring temperature record from western Himalayas (WH), for the period of 1876-2000. The SSA and wavelet spectra reveal the presence of 5 years short term ENSO variations to 11 year solar cycle indicating the influence of both the solar-geomagnetic and ENSO imprints in the tree ring data. The presence of 33-year cycle periodicity suggests the Sun-temperature variability probably involving the induced changes in the basic state of the atmosphere. Our wavelet analysis for the SSA reconstructed time series agrees with our previous results and also enhance the amplitude of the signals by removing the noise and showing a strong influence of solar-geomagnetic and ENSO patterns throughout the record. The solar flares are considered to be responsible for cause in the circulation patterns in the atmosphere. The net effect of solar-geomagnetic processes on temperature record thus appears to be the result of counteracting influences on shorter (about 5-6 years) and longer (about 11-12 years) time scales. The present analysis thus suggests that the influence of solar processes on Indian temperature variability operates in part indirectly through ENSO, but on more than one time scale. The analyses hence provides credible evidence for teleconnections of tropical pacific climatic variability with Indian climate ranging from interannual-decadal time scales and also demonstrate the possible role of exogenic triggering in reorganizing the global earth-ocean-atmospheric systems.

  12. PV Solar Radiometric Measurements

    SciTech Connect

    Myers, D.R.; Cannon, T.W.

    1997-02-01

    Radiometric measurements performed by the PV Solar Radiometric Measurements Task support NREL{close_quote}s centers for Measurements and Characterization, Performance Engineering and Reliability, and Renewable Energy Resources. The task provides characterization, measurements, testing, designs, and analysis of radiometric instrumentation and data for the performance of PV cells, modules, and systems. We describe recent characterization of the radiometric performance of pyranometers deployed for PV system testing at the NREL Outdoor Test Facility (OTF) and improvements undertaken in NREL broadband radiometer characterization. Typical measurement and calibration issues with diode array spectroradiometers used for absolute spectral measurements applied to PV performance and characterization are discussed. {copyright} {ital 1997 American Institute of Physics.}

  13. A Change in the Solar He II EUV Global Network Structure as an Indicator of the Geo-Effectiveness of Solar Minima

    NASA Technical Reports Server (NTRS)

    Didkovsky, L.; Gurman, J. B.

    2013-01-01

    Solar activity during 2007 - 2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor (SEM), one of instruments on the Charge Element and Isotope Analysis System (CELIAS) on board the Solar and Heliospheric Observatory (SOHO) for the two latest solar minima showed a decrease of the absolute irradiance of about 15 +/- 6 % during the solar minimum between Cycles 23 and 24 compared with the Cycle 22/23 minimum when a yearly running-mean filter was used. We found that some local, shorter-term minima including those with the same absolute EUV flux in the SEM spectral band show a higher concentration of spatial power in the global network structure from the 30.4 nm SOHO/Extreme ultraviolet Imaging Telescope (EIT) images for the local minimum of 1996 compared with the minima of 2008 - 2011.We interpret this higher concentration of spatial power in the transition region's global network structure as a larger number of larger-area features on the solar disk. These changes in the global network structure during solar minima may characterize, in part, the geo-effectiveness of the solar He II EUV irradiance in addition to the estimations based on its absolute levels.

  14. Inferring water vapor amounts with solar spectral irradiance: Measurements, modeling, and comparisons with in situ water vapor profiles in the upper troposphere lower stratosphere from ATTREX

    NASA Astrophysics Data System (ADS)

    Kindel, B. C.; Pilewskie, P.; Schmidt, S.; Thornberry, T. D.; Rollins, D. W.; LeBlanc, S. E.; Bui, T. V.

    2013-12-01

    The Airborne Tropical TRopopause Experiment (ATTREX) flew six science missions on the NASA Global Hawk aircraft from NASA Dryden, California to the Pacific tropics to sample the upper troposphere, lower stratosphere (UTLS) during February and March of 2013. After transit to the tropics, the aircraft performed a series of vertical profiles from the cruising altitude of about 18 km down to 14 km sampling the tropical tropopause layer (TTL). A science focus of ATTREX is to examine water vapor and its transport through the TTL. The extremely cold temperatures found in the TTL act to limit the transport of water vapor from the troposphere to stratosphere, making this region critical to the water vapor budget of the stratosphere. Here we investigate the use of the strong water bands centered at 1400 and 1900 nm in the telluric solar spectrum to infer the small water vapor amounts through the TTL. Measurements of spectral irradiance from the Solar Spectral Flux Radiometer (SSFR) at the top and bottom of the aircraft profiles are used to produce transmission spectra. These are compared with atmospheric radiative transfer calculations of transmission through the layer. The measured water vapor profile from the NOAA water vapor instrument, as well as temperature and pressure, were used in the modeling, providing a rare opportunity to compare water vapor amount inferred from solar transmittance to in situ measurements. Prospects for the use of these bands for determining the total column water vapor amount from the UTLS to the top of the atmosphere from aircraft are also discussed.

  15. Nonlinear generation of kinetic-scale waves by magnetohydrodynamic Alfvén waves and nonlocal spectral transport in the solar wind

    SciTech Connect

    Zhao, J. S.; Wu, D. J.; Voitenko, Y.; De Keyser, J.

    2014-04-20

    We study the nonlocal nonlinear coupling and generation of kinetic Alfvén waves (KAWs) and kinetic slow waves (KSWs) by magnetohydrodynamic Alfvén waves (MHD AWs) in conditions typical for the solar wind in the inner heliosphere. This cross-scale process provides an alternative to the turbulent energy cascade passing through many intermediate scales. The nonlinearities we study are proportional to the scalar products of wave vectors and hence are called 'scalar' ones. Despite the strong Landau damping of kinetic waves, we found fast growing KAWs and KSWs at perpendicular wavelengths close to the ion gyroradius. Using the parametric decay formalism, we investigate two independent decay channels for the pump AW: forward decay (involving co-propagating product waves) and backward decay (involving counter-propagating product waves). The growth rate of the forward decay is typically 0.05 but can exceed 0.1 of the pump wave frequency. The resulting spectral transport is nonlocal and anisotropic, sharply increasing perpendicular wavenumbers but not parallel ones. AWs and KAWs propagating against the pump AW grow with about the same rate and contribute to the sunward wave flux in the solar wind. Our results suggest that the nonlocal decay of MHD AWs into KAWs and KSWs is a robust mechanism for the cross-scale spectral transport of the wave energy from MHD to dissipative kinetic scales in the solar wind and similar media.

  16. Geometries, Electronic Structures, And Spectral Properties Of Some Metal Free Phthalonitrile Derivatives For Enhancement Of The Dye Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Anbarasan, P. M.

    2010-08-01

    New technologies for direct solar energy conversion have gained more attention in the last few years. In particular, Dye Sensitized Solar Cells (DSSCs) are promising in terms of efficiency and low cost [1,2]. Benefited from systematic device engineering and continuous material innovation, a state of the art DSC with a ruthenium sensitizer has achieved a validated efficiency of 11.1%[3] measured under the air mass 1.5 global (AM1.5G) conditions. The optimized geometries of the 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(a). The frontier molecular orbitals (MO) energies of the dyes 3, 4 Pyridinedicarbonitrile, 3-Nitrophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(b). The HOMO-LUMO gap of the dye 3, 4 Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile in vacuum is 5.96 eV, 5.54 eV, 5.57 eV, 5.76 eV respectively. The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of dyes 3, 4-Pyridinedicarbonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile were studied by using density functional theory with hybrid functional B3LYP, and the UV-Vis spectra were investigated by using TDDFT methods. The NBO results suggest that 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile 4-Aminophthalonitrile and 4-Methylphthalonitrile are all (D-pi-A) systems. The calculated isotropic polarizability of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is. 85.76, 112.72, 26.63 and 115.13 a.u., respectively. The calculated polarizability anisotropy invariant of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 74.451, 83.533, 62.653 and 88.526 a.u., respectively. The hyperpolarizabilities of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 0

  17. Geometries, Electronic Structures, And Spectral Properties Of Some Metal Free Phthalonitrile Derivatives For Enhancement Of The Dye Sensitized Solar Cells

    SciTech Connect

    Anbarasan, P. M.

    2010-08-06

    New technologies for direct solar energy conversion have gained more attention in the last few years. In particular, Dye Sensitized Solar Cells (DSSCs) are promising in terms of efficiency and low cost [1,2]. Benefited from systematic device engineering and continuous material innovation, a state of the art DSC with a ruthenium sensitizer has achieved a validated efficiency of 11.1%[3] measured under the air mass 1.5 global (AM1.5G) conditions.The optimized geometries of the 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(a). The frontier molecular orbitals (MO) energies of the dyes 3, 4 Pyridinedicarbonitrile, 3-Nitrophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(b). The HOMO-LUMO gap of the dye 3, 4 Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile in vacuum is 5.96 eV, 5.54 eV, 5.57 eV, 5.76 eV respectively. The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of dyes 3, 4-Pyridinedicarbonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile were studied by using density functional theory with hybrid functional B3LYP, and the UV-Vis spectra were investigated by using TDDFT methods. The NBO results suggest that 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile 4-Aminophthalonitrile and 4-Methylphthalonitrile are all (D-pi-A) systems. The calculated isotropic polarizability of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is. 85.76, 112.72, 26.63 and 115.13 a.u., respectively. The calculated polarizability anisotropy invariant of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 74.451, 83.533, 62.653 and 88.526 a.u., respectively. The hyperpolarizabilities of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 0

  18. 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

  19. 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.

  20. Absolute line intensities in CO2 bands near 4.8 microns

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Benner, D. C.; Devi, V. M.

    1986-01-01

    Absolute intensities for 726 unblended lines in 20 bands of C-12(O-16)2, C-13(O-16)2, O-16C-12O-18, and O-16C-12O-17 in the 4.8-micron spectral region have been determined using a natural sample of ultrahigh-purity CO2. Spectral data were recorded at low pressure (less than 10 torr) and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. Derived vibrational band intensities and coefficients of the F factor for each band were compared to values of the 1982 Air Force Geophysics Laboratory line parameters compilation. The present work fills out the CO2 lines in the 5-micron band systems. Lines in the strongest of these measured bands are being used to infer atmospheric pressure from high-resolution stratospheric spectra recorded during the Spacelab 3 Atmospheric Trace Molecule Spectroscopy experiment.

  1. Simple solar spectral model for direct and diffuse irradiance on horizontal and tilted planes at the earth's surface for cloudless atmospheres

    SciTech Connect

    Bird, R.; Riordan, C.

    1984-12-01

    A new, simple model for calculating clear-sky direct and diffuse spectral irradiance on horizontal and tilted surfaces is presented. The model is based on previously reported simple algorithms and on comparisons with rigorous radiative transfer calculations and limited outdoor measurements. Equations for direct normal irradiance are outlined; and include: Raleigh scattering; aerosol scattering and absorption; water vapor absorption; and ozone and uniformly mixed gas absorption. Inputs to the model include solar zenith angle, collector tilt angle, atmospheric turbidity, amount of ozone and precipitable water vapor, surface pressure, and ground albedo. The model calculates terrestrial spectra from 0.3 to 4.0 ..mu..m with approximately 10 nm resolution. A major goal of this work is to provide researchers with the capability to calculate spectral irradiance for different atmospheric conditions and different collector geometries using microcomputers. A listing of the computer program is provided.

  2. The TIMED solar EUV experiment

    SciTech Connect

    Woods, T.N.; Rottman, G.J.; Roble, R.; White, O.R.; Solomon, S.C.; Lawrence, G.; Lean, J.; Tobiska, W.K.

    1994-12-31

    The Solar EUV Experiment (SEE) investigation contributes primarily to the NASA Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics (TIMED) mission goal to characterize the sources of energy responsible for the thermal structure of the mesosphere, the lower thermosphere, and the ionosphere (MLTI). These energy sources include solar radiation, solar energetic particles, Joule heating, conduction, dynamical forcing, and chemical energy release. Of these energy inputs, the solar vacuum ultraviolet (VUV) radiation below 200 nm is the dominant global energy source for heating of the thermosphere, creating the ionosphere, and driving the diurnal cycles of wind and chemistry. The Solar EUV Experiment selected for the NASA TIMED mission will measure the solar vacuum ultraviolet (VUV) spectral irradiance from 0.1 to 200 nm. To cover this wide spectral range two different types of instruments are used: a grating spectrograph for spectra above 25 nm and an avalanche photodiode for spectra below 25 nm. As part of the in-flight calibration plan, silicon XUV photodiodes with thin film filters are used as stable broadband photometers between 0.1 and 40 nm. In addition, redundant spectrograph and avalanche photodiode capabilities provide calibration checks on the time scale of a month, and annual rocket underflight measurements provide absolute calibration checks traceable to NIST photometric standards. All three types of instruments have been developed and flight proven as part of a NASA solar EUV irradiance rocket experiment.

  3. Study of gap states in a-Si:H alloys by measurements of photoconductivity and spectral response of MIS solar cells

    NASA Astrophysics Data System (ADS)

    Vanier, P. E.; Delahoy, A. E.; Griffith, R. W.

    1981-06-01

    A picture of the density of gap states n (E) in glow discharge a-Si:H is constructed using four different kinds of transport measurement on a large number of samples. The minimum in n (E) lies 0.4 eV below Ec, rather than in the middle of the gap. A distribution of fast recombination centers lies at mid-gap, and two sets of hole traps lie between mid-gap and the valence band. Modifications in n (E) have been studied by the effects of selected impurities on the conversion efficiency and spectral response of MIS and pin solar cells.

  4. Carbon nanotube-based tandem absorber with tunable spectral selectivity: transition from near-perfect blackbody absorber to solar selective absorber.

    PubMed

    Selvakumar, N; Krupanidhi, S B; Barshilia, Harish C

    2014-04-23

    CVD grown CNT thin film with a thickness greater than 10 μm behaves like a near-perfect blackbody absorber (i.e., α/ε = 0.99/0.99). Whereas, for a thickness ≤ 0.4 µm, the CNT based tandem absorber acts as a spectrally selective coating (i.e., α/ε = 0.95/0.20). These selective coatings exhibit thermal stability up to 650 °C in vacuum, which can be used for solar thermal power generation. PMID:24474148

  5. Spectral Studies of UV and Solar Photocatalytic Degradation of AZO Dye and Textile Dye Effluents Using Green Synthesized Silver Nanoparticles

    PubMed Central

    Mariselvam, R.; Ranjitsingh, A. J. A.; Mosae Selvakumar, P.; Alarfaj, Abdullah A.; Munusamy, Murugan A.

    2016-01-01

    The photocatalytic degradation of the chemical dye AZO and dye effluents in different time duration has been investigated using biologically synthesized silver nanoparticles. Dye industry effluents and AZO dye undergo degradation to form harmless intermediate and colourless products following irradiation by UV and solar light in the presence of green synthesized silver nanoparticles. The degree of degradation was tested under the experimental conditions such as PH, temperature, and absorbance of the dye in UV and solar light was measured. The degradation was higher in the UV light source than in the solar light source. Green synthesized silver nanoparticles in the UV light source were found to expedite the dye degradation process. PMID:27382364

  6. Measurement of the solar constant

    NASA Technical Reports Server (NTRS)

    Crommelynck, D.

    1981-01-01

    The absolute value of the solar constant and the long term variations that exist in the absolute value of the solar constant were measured. The solar constant is the total irradiance of the Sun at a distance of one astronomical unit. An absolute radiometer removed from the effects of the atmosphere with its calibration tested in situ was used to measure the solar constant. The importance of an accurate knowledge of the solar constant is emphasized.

  7. 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.

  8. The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared - Part 2: Accurate calibration of high spectral-resolution infrared measurements of surface solar radiation

    NASA Astrophysics Data System (ADS)

    Reichert, Andreas; Rettinger, Markus; Sussmann, Ralf

    2016-09-01

    Quantitative knowledge of water vapor absorption is crucial for accurate climate simulations. An open science question in this context concerns the strength of the water vapor continuum in the near infrared (NIR) at atmospheric temperatures, which is still to be quantified by measurements. This issue can be addressed with radiative closure experiments using solar absorption spectra. However, the spectra used for water vapor continuum quantification have to be radiometrically calibrated. We present for the first time a method that yields sufficient calibration accuracy for NIR water vapor continuum quantification in an atmospheric closure experiment. Our method combines the Langley method with spectral radiance measurements of a high-temperature blackbody calibration source (< 2000 K). The calibration scheme is demonstrated in the spectral range 2500 to 7800 cm-1, but minor modifications to the method enable calibration also throughout the remainder of the NIR spectral range. The resulting uncertainty (2σ) excluding the contribution due to inaccuracies in the extra-atmospheric solar spectrum (ESS) is below 1 % in window regions and up to 1.7 % within absorption bands. The overall radiometric accuracy of the calibration depends on the ESS uncertainty, on which at present no firm consensus has been reached in the NIR. However, as is shown in the companion publication Reichert and Sussmann (2016), ESS uncertainty is only of minor importance for the specific aim of this study, i.e., the quantification of the water vapor continuum in a closure experiment. The calibration uncertainty estimate is substantiated by the investigation of calibration self-consistency, which yields compatible results within the estimated errors for 91.1 % of the 2500 to 7800 cm-1 range. Additionally, a comparison of a set of calibrated spectra to radiative transfer model calculations yields consistent results within the estimated errors for 97.7 % of the spectral range.

  9. Investigating the ion-scale spectral break of solar wind turbulence from low to high plasma beta with high-resolution hybrid simulations

    NASA Astrophysics Data System (ADS)

    Franci, Luca; Landi, Simone; Matteini, Lorenzo; Verdini, Andrea; Hellinger, Petr

    2016-04-01

    We investigate the properties of the ion-scale spectral break of solar wind turbulence by means of two-dimensional, large-scale, high-resolution hybrid particle-in-cell simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we add a spectrum of in-plane large- scale magnetic and kinetic fluctuations, with energy equipartition and vanishing correlation. We perform a set of ten simulations with different values of the ion plasma beta, β_i. In all cases, we observe the power spectrum of the total magnetic fluctuations following a power law with a spectral index of -5/3 in the inertial range, with a smooth break around ion scales and a steeper power law in the sub-ion range. This spectral break always occurs at spatial scales of the order of the proton gyroradius, ρ_i, and the proton inertial length, di = ρi / √{β_i}. When the plasma beta is of the order of 1, the two scales are very close to each other and determining which is directly related to the steepening of the spectra it's not straightforward at all. In order to overcome this limitation, we extended the range of values of βi over three orders of magnitude, from 0.01 to 10, so that the two ion scales were well separated. This let us observe that the break always seems to occur at the larger of the two scales, i.e., at di for βi 1. The effect of βi on the spectra of the parallel and perpendicular magnetic components separately and of the density fluctuations is also investigated. We compare all our numerical results with solar wind observations and suggest possible explanations for our findings.

  10. Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

    NASA Technical Reports Server (NTRS)

    Zodivaz, A. M.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Takakura, T.; Cliver, E. W.; Tapping, K. F.

    1986-01-01

    A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz.

  11. Completing the Next Generation Spectral Library

    NASA Astrophysics Data System (ADS)

    Gregg, Michael

    2014-10-01

    We propose to complete our STIS UV+optical snapshot program, the Next Generation SpectralLibrary, which now stands at 380 targets. When complete the NGSL will comprise 600 stars,roughly equally divided among four metallicities, very low {[Fe/H] < -1.5}, low {-1.5 <[Fe/H] < -0.5}, near-solar {-0.3 < [Fe/H] < 0.1}, and super-solar {[Fe/H] > 0.2},well-sampling the entire HR-diagram in each bin. The finished NGSL will be invaluable formodeling the integrated light of galaxies and clusters, as well as calibrating the stellareffective temperature scale to <1% precision. Included in the updated target list forCycle 22 are select "touchstone" stars with precise radii measured with long baselineinterferometry, which will be used in the absolute calibration of the stellar effectivetemperature scale. Upon completion, the NGSL will surpass all extant spectral librariesbecause of its combination of UV spectral coverage and comprehensive metallicity range,with lasting archival value well into the JWST era and beyond. Because of the universalutility and community-broad nature of this venture, we waive the proprietary period.While snapshot proposals are ineligible for the UV initiative, the scientific returns fromthis program stem mainly from the HST/STIS UV capabilities.

  12. Collection efficiency measurements for solar cell research

    NASA Technical Reports Server (NTRS)

    Hampton, H. L.; Olsen, L. C.

    1976-01-01

    A system was established for measuring absolute, spectral collection efficiency that is well suited to solar cell research and development. Determination of spectral collection efficiency involves measurements of the incident photon intensity, the device reflection coefficient, and the cell short circuit current. A monochromatic photon flux is obtained with a high intensity Bausch and Lomb monochromator, and an Epply thermopile detector is used to measure incident intensity. Normal incidence reflectivity measurements are achieved with a prism type beam splitter. The experimental approach is discussed, measurements of the reflectivity of evaporated silver films are considered. Collection efficiency measurements of silicon solar cells are presented, and collection efficiency studies of Cu20 solar cells are discussed.

  13. Resolving Differences in Absolute Irradiance Measurements Between the SOHO/CELIAS/SEM and the SDO/EVE

    NASA Astrophysics Data System (ADS)

    Wieman, S. R.; Didkovsky, L. V.; Judge, D. L.

    2014-08-01

    The Solar EUV Monitor (SEM) onboard SOHO has measured absolute extreme ultraviolet (EUV) and soft X-ray solar irradiance nearly continuously since January 1996. The EUV Variability Experiment (EVE) on SDO, in operation since April of 2010, measures solar irradiance in a wide spectral range that encompasses the band passes (26 - 34 nm and 0.1 - 50 nm) measured by SOHO/SEM. However, throughout the mission overlap, irradiance values from these two instruments have differed by more than the combined stated uncertainties of the measurements. In an effort to identify the sources of these differences and eliminate them, we investigate in this work the effect of reprocessing the SEM data using a more accurate SEM response function (obtained from synchrotron measurements with a SEM sounding-rocket clone instrument taken after SOHO was already in orbit) and time-dependent, measured solar spectral distributions - i.e., solar reference spectra that were unavailable prior to the launch of the SDO. We find that recalculating the SEM data with these improved parameters reduces mean differences with the EVE measurements from about 20 % to less than 5 % in the 26 - 34 nm band, and from about 35 % to about 15 % for irradiances in the 0.1 - 7 nm band extracted from the SEM 0.1 - 50 nm channel.

  14. Transient climate simulation from the Maunder Minimum to present day using prescribed changes in GHG, total/spectral solar irradiance and ozone

    NASA Astrophysics Data System (ADS)

    Spangehl, Thomas; Cubasch, Ulrich; Schimanke, Semjon

    A fully coupled AO-GCM including representation of the middle atmosphere is used for tran-sient simulation of climate from 1630 to 2000 AD. For better representation of changes in the UV/visible part of the solar spectrum an improved short-wave radiation scheme is implemented. The model is driven by changes in GHG concentrations, solar activity and volcanic eruptions. Solar variability is introduced via changes in total/spectral solar irradiance (TSI/SSI) and pre-scribed changes in stratospheric ozone. The secular trend in TSI is in the range of 0.1 percent increase from Maunder Minimum to present-day. Volcanic eruptions are represented via abrupt reduction in TSI. With the applied forcings the model does not simulate a clear reduction of the annual Northern Hemisphere (NH) mean near surface temperature during Maunder Minimum. By contrast the Dalton Minimum is characterized by distinct cooling and there is a significant raise of NH mean near surface temperature until the end of the 20th century. Focusing on the North Atlantic/European region the winter mean near surface temperature change pat-tern from Late Maunder Minimum (1675-1715) to present-day (1960-1990) reveals maximum warming over north-eastern Europe and cooling over the western North Atlantic with maxi-mum cooling west of Greenland. These changes can partly be explained by a shift of the NAO towards a more positive phase. The simulated changes in tropospheric circulation are discussed with special emphasize on the role of the solar forcing. Besides the stratospheric solar forcing which may affect NAO variability via downward propagation of the solar signal from the strato-sphere to the troposphere the magnitude of the secular trend in TSI might play a role. For the period from Maunder Minimum to present-day the simulation shows less near surface temper-ature increase especially over arctic regions when compared to simulations performed with the same model including the standard radiation scheme but

  15. Apple flavonols during fruit adaptation to solar radiation: spectral features and technique for non-destructive assessment.

    PubMed

    Merzlyak, Mark N; Solovchenko, Alexei E; Smagin, Alexei I; Gitelson, Anatoly A

    2005-02-01

    Spectral properties of flavonols of three varieties (Golden Delicious, Antonovka, and Renet Simirenko) of anthocyanin-free apple fruit were investigated with reflectance spectroscopy. The results of spectral and biochemical analyses suggested that fruit reflectance in a broad spectral range 365-430 nm is strongly dependent on and, in sunlit fruit surfaces, governed by flavonols. The build up of peel flavonols (mainly rutin and other quercetin glycosides) resulted in a dramatic decrease of fruit reflectance in this range, flattening of the spectrum, and extending the region with low reflectance (4-5%) to ca. 410 nm. The spectral features observed suggest that flavonols contribute significantly to screening of excessive radiation, not only UV-A, but in the short-wave bands of chlorophyll and carotenoid absorption in the visible part of the spectrum as well. To retrieve quantitatively flavonol content from reflectance spectra, we tested the applicability of an inversion technique developed for non-destructive leaf pigment assessment. The model for flavonol content assessment was suggested in the form (R(-1)410 - R(-1)460)R800, where Rlambda is reflectance at wavelength lambda. The model was linearly related to flavonol content between 8 and 220nmol/cm2 with the coefficient of determination r2=0.92 and root mean square error of flavonol estimation of 20 nmol/ cm2 regardless of cultivar, chlorophyll, and carotenoid content.

  16. Spectral Studies of UV and Solar Photocatalytic Degradation of AZO Dye and Textile Dye Effluents Using Green Synthesized Silver Nanoparticles.

    PubMed

    Mariselvam, R; Ranjitsingh, A J A; Mosae Selvakumar, P; Alarfaj, Abdullah A; Munusamy, Murugan A

    2016-01-01

    The photocatalytic degradation of the chemical dye AZO and dye effluents in different time duration has been investigated using biologically synthesized silver nanoparticles. Dye industry effluents and AZO dye undergo degradation to form harmless intermediate and colourless products following irradiation by UV and solar light in the presence of green synthesized silver nanoparticles. The degree of degradation was tested under the experimental conditions such as P(H), temperature, and absorbance of the dye in UV and solar light was measured. The degradation was higher in the UV light source than in the solar light source. Green synthesized silver nanoparticles in the UV light source were found to expedite the dye degradation process. PMID:27382364

  17. Controlling adverse and beneficial effects of solar UV radiation by wearing suitable clothes - spectral transmission of different kinds of fabrics.

    PubMed

    Sobolewski, Piotr S; Krzyścin, Janusz W; Jarosławski, Janusz; Wink, Jakub; Lesiak, Aleksandra; Narbutt, Joanna

    2014-11-01

    Humans should avoid prolonged exposure to the Sun during the warm subperiod of the year with naturally high solar UV level. One of the known recommendations to avoid excessive UV radiation is wearing clothes with UV protection additives. However there is an important question: how do we get an adequate solar UV radiation, which maintains a healthy status of vitamin D, without facing overexposure risks? It is found that some kind of 100% cotton knitted fabric, used in the production of normal daily clothing, has ∼15% transmittance of solar UV. Model studies show that a garment made of this fabric allows larger synthesis of vitamin D3 in human body without the erythema risks (skin redness). Thus the adequate level of vitamin D could be attained safely by a person exposing only small part of the body (face, palms) during the period (May-August) of the year. PMID:25113622

  18. Hilbert-Huang spectral analysis for characterizing the intrinsic time-scales of variability in decennial time-series of surface solar radiation

    NASA Astrophysics Data System (ADS)

    Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

    2016-04-01

    An analysis of the variability of the surface solar irradiance (SSI) at different local time-scales is presented in this study. Since geophysical signals, such as long-term measurements of the SSI, are often produced by the non-linear interaction of deterministic physical processes that may also be under the influence of non-stationary external forcings, the Hilbert-Huang transform (HHT), an adaptive, noise-assisted, data-driven technique, is employed to extract locally - in time and in space - the embedded intrinsic scales at which a signal oscillates. The transform consists of two distinct steps. First, by means of the Empirical Mode Decomposition (EMD), the time-series is "de-constructed" into a finite number - often small - of zero-mean components that have distinct temporal scales of variability, termed hereinafter the Intrinsic Mode Functions (IMFs). The signal model of the components is an amplitude modulation - frequency modulation (AM - FM) one, and can also be thought of as an extension of a Fourier series having both time varying amplitude and frequency. Following the decomposition, Hilbert spectral analysis is then employed on the IMFs, yielding a time-frequency-energy representation that portrays changes in the spectral contents of the original data, with respect to time. As measurements of surface solar irradiance may possibly be contaminated by the manifestation of different type of stochastic processes (i.e. noise), the identification of real, physical processes from this background of random fluctuations is of interest. To this end, an adaptive background noise null hypothesis is assumed, based on the robust statistical properties of the EMD when applied to time-series of different classes of noise (e.g. white, red or fractional Gaussian). Since the algorithm acts as an efficient constant-Q dyadic, "wavelet-like", filter bank, the different noise inputs are decomposed into components having the same spectral shape, but that are translated to the

  19. 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.

  20. Precision spectroscopy with a frequency-comb-calibrated solar spectrograph

    NASA Astrophysics Data System (ADS)

    Doerr, H.-P.

    2015-06-01

    The measurement of the velocity field of the plasma at the solar surface is a standard diagnostic tool in observational solar physics. Detailed information about the energy transport as well as on the stratification of temperature, pressure and magnetic fields in the solar atmosphere are encoded in Doppler shifts and in the precise shape of the spectral lines. The available instruments deliver data of excellent quality and precision. However, absolute wavelength calibration in solar spectroscopy was so far mostly limited to indirect methods and in general suffers from large systematic uncertainties of the order of 100 m/s. During the course of this thesis, a novel wavelength calibration system based on a laser frequency comb was deployed to the solar Vacuum Tower Telescope (VTT), Tenerife, with the goal of enabling highly accurate solar wavelength measurements at the level of 1 m/s on an absolute scale. The frequency comb was developed in a collaboration between the Kiepenheuer-Institute for Solar Physics, Freiburg, Germany and the Max Planck Institute for Quantum Optics, Garching, Germany. The efforts cumulated in the new prototype instrument LARS (Lars is an Absolute Reference Spectrograph) for solar precision spectroscopy which is in preliminary scientific operation since~2013. The instrument is based on the high-resolution echelle spectrograph of the VTT for which feed optics based on single-mode optical fibres were developed for this project. The setup routinely achieves an absolute calibration accuracy of 60 cm/s and a repeatability of 2.5 cm/s. An unprecedented repeatability of only 0.32 cm/s could be demonstrated with a differential calibration scheme. In combination with the high spectral resolving power of the spectrograph of 7x10^5 and virtually absent internal scattered light, LARS provides a spectral purity and fidelity that previously was the domain of Fourier-transform spectrometers only. The instrument therefore provides unique capabilities for

  1. Reflected solar radiation from horizontal, vertical and inclined surfaces: ultraviolet and visible spectral and broadband behaviour due to solar zenith angle, orientation and surface type.

    PubMed

    Turner, J; Parisi, A V; Turnbull, D J

    2008-07-24

    Ultraviolet (UV) radiation affects human life and UV exposure is a significant everyday factor that individuals must be aware of to ensure minimal damaging biological effects to themselves. UV exposure is affected by many complex factors. Albedo is one factor, involving reflection from flat surfaces. Albedo is defined as the ratio of reflected (upwelling) irradiance to incident (downwelling) irradiance and is generally accepted only for horizontal surfaces. Incident irradiance on a non horizontal surface from a variety of incident angles may cause the reflectivity to change. Assumptions about the reflectivity of a vertical surface are frequently made for a variety of purposes but are rarely quantified. As urban structures are dominated by vertical surfaces, using albedo to estimate influence on UV exposure is limiting when incident (downwelling) irradiance is not normal to the surface. Changes to the incident angle are affected by the solar zenith angle, surface position and orientation and surface type. A new characteristic describing reflection from a surface has been used in this research. The ratio of reflected irradiance (from any surface position of vertical, horizontal or inclined) to global (or downwelling) irradiance (RRG) has been calculated for a variety of metal building surfaces in winter time in the southern hemisphere for both the UV and visible radiation spectrum, with special attention to RRG in the UV spectrum. The results show that the RRG due to a vertical surface can exceed the RRG due to a horizontal surface, at smaller solar zenith angles as well as large solar zenith angles. The RRG shows variability in reflective capacities of surface according to the above mentioned factors and present a more realistic influence on UV exposure than albedo for future investigations. Errors in measuring the RRG at large solar zenith angles are explored, which equally highlights the errors in albedo measurement at large solar zenith angles. PMID:18490174

  2. 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.

  3. SSBUV and NOAA-11 SBUV/2 Solar Variability Measurements

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Cebula, Richard P.; Hilsenrath, Ernest

    1998-01-01

    The Shuttle SBUV (SSBUV) and NOAA-11 SBUV/2 instruments measured solar spectral UV irradiance during the maximum and declining phase of solar cycle 22. The SSB UV data accurately represent the absolute solar UV irradiance between 200-405 nm, and also show the long-term variations during eight flights between October 1989 and January 1996. These data have been used to correct long-term sensitivity changes in the NOAA-11 SBUV/2 data, which provide a near-daily record of solar UV variations over the 170-400 nm region between December 1988 and October 1994. The NOAA-11 data demonstrate the evolution of short-term solar UV activity during solar cycle 22.

  4. Systematic Charge-to-Mass-Dependence of Heavy Ion Spectral Breaks in Large Gradual Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Mason, Glenn; Ebert, Robert; Dayeh, Maher; McComas, David; Li, Gang; Mewaldt, Richard; Cohen, Christina; Schwadron, Nathan; Snith, Charles

    2016-04-01

    We fit the ˜0.1-500 MeV nucleon-1 H-Fe spectra in 46 large SEP events surveyed by Desai et al. (2015) with the double power-law Band function to obtain a normalization constant, low- and high-energy Band parameters γaand γb; and spectral break energy EB. We also calculate the low-energy power-law spectral slope γ1. Our results are: 1) γa, γ1, andγb are species-independent and the spectra steepen with increasing energy; 2) the low-energy power-law spectral slopes γ1are consistent with diffusive acceleration at shocks with compression ratios between ˜2 - 4 as predicted by Schwadron et al. (2015); 3) the spectral breaks EB's are well ordered by Q/M ratio, and decrease systematically with decreasing Q/M, scaling as (Q/M)α with α in most events varying between ˜0.2-2, as predicted by Li et al (2009); 4) α is well correlated with Fe/O at ˜0.16-0.23 MeV nucleon-1, but not with the ˜15-21 MeV nucleon-1 Fe/O and the ˜0.5-2.0 MeV nucleon-1 3He/4He ratios; 5) In most events: α <1.4, the spectra steepen significantly at higher energy with γb-γa >3, and O EB increases with γb-γa; and 6) Many extreme events (associated with faster CMEs and GLEs) are Fe-rich and 3He-rich, have large α ≥1.4, flatter spectra at low and high energies with γb-γa <3, and EB that anti-correlates with γb-γa. In most events, the Q/M-dependence of EB is consistent with the equal diffusion coefficient condition, while the event-to-event variations in α may be driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker when compared to extreme events. We interpret these results as being due to weaker turbulence that allows the SEPs to easily escape, resulting in weaker Q/M-dependence of EB, lower α values, and spectral steepening at higher energies. In contrast for extreme events, the stronger Q/M-dependence of EB, larger α values, and harder spectra at high and low energy occur because enhanced wave

  5. Systematic Charge-to-Mass-Dependence of Heavy Ion Spectral Breaks in Large Gradual Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Mason, Glenn; Ebert, Robert; Dayeh, Maher; McComas, David; Li, Gang; Mewaldt, Richard; Cohen, Christina; Schwadron, Nathan; Snith, Charles

    2016-04-01

    We fit the ˜0.1-500 MeV nucleon‑1 H-Fe spectra in 46 large SEP events surveyed by Desai et al. (2015) with the double power-law Band function to obtain a normalization constant, low- and high-energy Band parameters γaand γb; and spectral break energy EB. We also calculate the low-energy power-law spectral slope γ1. Our results are: 1) γa, γ1, andγb are species-independent and the spectra steepen with increasing energy; 2) the low-energy power-law spectral slopes γ1are consistent with diffusive acceleration at shocks with compression ratios between ˜2 - 4 as predicted by Schwadron et al. (2015); 3) the spectral breaks EB's are well ordered by Q/M ratio, and decrease systematically with decreasing Q/M, scaling as (Q/M)α with α in most events varying between ˜0.2-2, as predicted by Li et al (2009); 4) α is well correlated with Fe/O at ˜0.16-0.23 MeV nucleon‑1, but not with the ˜15-21 MeV nucleon‑1 Fe/O and the ˜0.5-2.0 MeV nucleon‑1 3He/4He ratios; 5) In most events: α <1.4, the spectra steepen significantly at higher energy with γb-γa >3, and O EB increases with γb-γa; and 6) Many extreme events (associated with faster CMEs and GLEs) are Fe-rich and 3He-rich, have large α ≥1.4, flatter spectra at low and high energies with γb-γa <3, and EB that anti-correlates with γb-γa. In most events, the Q/M-dependence of EB is consistent with the equal diffusion coefficient condition, while the event-to-event variations in α may be driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker when compared to extreme events. We interpret these results as being due to weaker turbulence that allows the SEPs to easily escape, resulting in weaker Q/M-dependence of EB, lower α values, and spectral steepening at higher energies. In contrast for extreme events, the stronger Q/M-dependence of EB, larger α values, and harder spectra at high and low energy occur because enhanced

  6. Study of gap states in a-Si:H alloys by measurements of photoconductivity and spectral response of MIS solar cells

    SciTech Connect

    Vanier, P.E.; Delahoy, A.E.; Griffith, R.W.

    1981-01-01

    A picture of the density of gap states n(E) in glow discharge a-Si:H is constructed using four different kinds of transport measurement on a large number of samples. The minimum in n(E) lies 0.4 eV below E/sub c/, rather than in the middle of the gap. A distribution of fast recombination centers lies at mid-gap, and two sets of hole traps lie between mid-gap and the valence band. Modifications in n(E) have been studied by the effects of selected impurities on the conversion efficiency and spectral response of MIS and p-i-n solar cells.

  7. 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.

  8. 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.

  9. ON SPECTRAL BREAKS IN THE POWER SPECTRA OF MAGNETIC FLUCTUATIONS IN FAST SOLAR WIND BETWEEN 0.3 AND 0.9 AU

    SciTech Connect

    Bourouaine, S.; Marsch, E.; Alexandrova, O.; Maksimovic, M.

    2012-04-20

    We analyze the radial variation of the power spectra of the magnetic field from 0.3 to about 0.9 AU, using Helios 2 spacecraft measurements in the fast solar wind. The time resolution of the magnetic field data allows us to study the power spectra up to 2 Hz. Generally, the corresponding spectral break frequency f{sub b} and the Doppler-shifted frequencies, which are related to the proton gyroradius and inertial scales, are close to a frequency f of about 0.5 Hz at a distance of 1 AU from the Sun. However, studying the radial evolution of the power spectra offers us the possibility to distinguish between those scales. Recent Ulysses observations show that, while the proton scales vary, f{sub b} stays nearly constant with the heliocentric distance R. In our study we confirm that f{sub b} varies within a small interval of [0.2, 0.4] Hz only, as R varies from 0.3 to 0.9 AU. Moreover, if we assume parallel propagating fluctuations (with respect to the solar wind flow or background magnetic field), we can show that none of the proton scales are coincident with the break scale. If, however, we take into account the two-dimensional nature of the turbulent fluctuations, then we can show that the spatial scale corresponding to f{sub b} (R) does follow the proton inertial scale, {lambda}{sub p}(R), but not the proton gyroradius scale, {rho}{sub p}(R), as a function of heliocentric distance. These observations indicate that the spectral break at the proton inertial scale might be related to the Hall effect, or be controlled by the ion-cyclotron damping of obliquely propagating fluctuations or the formation of current sheets scaling like {lambda}{sub p}, which could be responsible for ion heating through magnetic reconnection.

  10. 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.

  11. Hilbert-Huang Transform: A Spectral Analysis Tool Applied to Sunspot Number and Total Solar Irradiance Variations, as well as Near-Surface Atmospheric Variables

    NASA Astrophysics Data System (ADS)

    Barnhart, B. L.; Eichinger, W. E.; Prueger, J. H.

    2010-12-01

    Hilbert-Huang transform (HHT) is a relatively new data analysis tool which is used to analyze nonstationary and nonlinear time series data. It consists of an algorithm, called empirical mode decomposition (EMD), which extracts the cyclic components embedded within time series data, as well as Hilbert spectral analysis (HSA) which displays the time and frequency dependent energy contributions from each component in the form of a spectrogram. The method can be considered a generalized form of Fourier analysis which can describe the intrinsic cycles of data with basis functions whose amplitudes and phases may vary with time. The HHT will be introduced and compared to current spectral analysis tools such as Fourier analysis, short-time Fourier analysis, wavelet analysis and Wigner-Ville distributions. A number of applications are also presented which demonstrate the strengths and limitations of the tool, including analyzing sunspot number variability and total solar irradiance proxies as well as global averaged temperature and carbon dioxide concentration. Also, near-surface atmospheric quantities such as temperature and wind velocity are analyzed to demonstrate the nonstationarity of the atmosphere.

  12. European UV DataBase (EUVDB) as a repository and quality analyser for solar spectral UV irradiance monitored in Sodankylä

    NASA Astrophysics Data System (ADS)

    Heikkilä, Anu; Kaurola, Jussi; Lakkala, Kaisa; Matti Karhu, Juha; Kyrö, Esko; Koskela, Tapani; Engelsen, Ola; Slaper, Harry; Seckmeyer, Gunther

    2016-08-01

    Databases gathering atmospheric data have great potential not only as data storages but also in serving as platforms for coherent quality assurance (QA). We report on the flagging system and QA tools designed for and implemented in the European UV DataBase (EUVDB; http://uv.fmi.fi/uvdb/) for measured data on solar spectral UV irradiance. We confine the study on the data measured by Brewer #037 MkII spectroradiometer in Sodankylä (67.37° N, 26.63° E) in 1990-2014. The quality indicators associated with the UV irradiance spectra uploaded into the database are retrieved from the database and subjected to a statistical analysis. The study demonstrates the performance of the QA tools of the EUVDB. In addition, it yields an overall view of the availability and quality of the solar UV spectra recorded in Sodankylä over a quarter of a century. Over 90 % of the four main quality indicators are flagged as GREEN, indicating the highest achievable quality. For the BLACK flags, denoting data not meeting the pre-defined requirements, the percentages for all the indicators remain below 0.12 %.

  13. Spectral analysis of ionospheric disturbances in the phase delay and radio signal amplitude at limb paths according to the COSMIC data in periods of solar activity

    NASA Astrophysics Data System (ADS)

    Shmakov, A. V.; Gorbunov, M. E.

    2016-07-01

    Based on more than 4500 sessions of radio transillumination of Earth's atmosphere along the satellite-atmosphere-satellite path obtained in the COSMIC experiment, the distribution along latitude and over local time of the spatial spectra of variations in the ionospheric phase delay and signal amplitude has been analyzed. The spatial spectra have been calculated for two height ranges, i.e., 60-80 and 80-100 km. In the phase signal spectrum within the height range 80-100 km, the second maximum in the vicinity of a frequency of 7-8 rad/km is clearly seen. Its diurnal and latitudinal behavior and its decrease towards high latitudes in both hemispheres can also be seen. In the height range of 60-80 km, this maximum is hardly observed. Although solar flares can lead to substantial local changes in the electron concentration, no substantial difference in the behavior of the spectral densities of the amplitude and phase delay at long limb paths was observed within these two height ranges on days of active and quiet sun. The latter fact makes it possible to develop a united algorithm of optimal ionospheric correction of the radio occultation data independent of solar activity.

  14. Systematic Charge-to-Mass-Dependence of Heavy Ion Spectral Breaks in Large Gradual Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Mason, Glenn; McComas, David; Cohen, Christina; Smith, Charles; Ebert, Robert; Schwadron, Nathan; Li, Gang; Mewaldt, Richard; Dayeh, Maher A.

    2016-07-01

    We fit the ˜0.1-500 MeV/nucleon H-Fe spectra in 46 large SEP events surveyed by Desai et al. (2015) with the double power-law Band function to obtain a normalization constant, low- and high-energy Band parameters γ_a and γ_b; and spectral break energy E_B. We also calculate the low-energy power-law spectral slope γ_1. Our results are: 1) γ_a, γ_1, and γ_b are species-independent and the spectra steepen with increasing energy; 2) the low-energy power-law spectral slopes γ_1 are consistent with diffusive acceleration at shocks with compression ratios between ˜2-4 as predicted by Schwadron et al. (2015); 3) the spectral breaks E_B's are well ordered by Q/M ratio, and decrease systematically with decreasing Q/M, scaling as (Q/M)^α with α in most events varying between ˜0.2-2, as predicted by Li et al (2009); 4) α is well correlated with Fe/O at ˜0.16-0.23 MeV/nucleon, but not with the ˜15-21 MeV/nucleon Fe/O and the ˜0.5-2.0 MeV/nucleon ^3He/^4He ratios; 5) In most events: α<1.4, the spectra steepen significantly at higher energy with γ_b - γ_a >3, and O E_B increases with γ_b - γ_a; and 6) Many extreme events (associated with faster CMEs and GLEs) are Fe-rich and ^3He-rich, have α≳1.4, flatter spectra at low and high energies with γ_b - γ_a <3, and E_B that anti-correlates with γ_b - γ_a. In most events, the Q/M-dependence of E_B is consistent with the equal diffusion coefficient condition, while the event-to-event variations in α may be driven by differences in the near-shock wave intensity spectra, which are flatter than the Kolmogorov turbulence spectrum but weaker when than extreme events. We interpret these results as being due to weaker turbulence that allows the SEPs to easily escape, resulting in weaker Q/M-dependence of E_B, lower α values, and spectral steepening at higher energies. In contrast for extreme events, the stronger Q/M-dependence of E_B, larger α values, and harder spectra at high and low energy occur because

  15. Spectrally selective glazings

    SciTech Connect

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  16. 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.

  17. SOLAR VARIABILITY FROM 240 TO 1750 nm IN TERMS OF FACULAE BRIGHTENING AND SUNSPOT DARKENING FROM SCIAMACHY

    SciTech Connect

    Pagaran, J.; Weber, M.; Burrows, J.

    2009-08-01

    The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

  18. Solar Variability from 240 to 1750 nm in Terms of Faculae Brightening and Sunspot Darkening from SCIAMACHY

    NASA Astrophysics Data System (ADS)

    Pagaran, J.; Weber, M.; Burrows, J.

    2009-08-01

    The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

  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. Analysis of bias voltage dependent spectral response in Ga{sub 0.51}In{sub 0.49}P/Ga{sub 0.99}In{sub 0.01}As/Ge triple junction solar cell

    SciTech Connect

    Sogabe, Tomah Ogura, Akio; Okada, Yoshitaka

    2014-02-21

    Spectral response measurement plays great role in characterizing solar cell device because it directly reflects the efficiency by which the device converts the sunlight into an electrical current. Based on the spectral response results, the short circuit current of each subcell can be quantitatively determined. Although spectral response dependence on wavelength, i.e., the well-known external quantum efficiency (EQE), has been widely used in characterizing multijunction solar cell and has been well interpreted, detailed analysis of spectral response dependence on bias voltage (SR −V{sub bias}) has not been reported so far. In this work, we have performed experimental and numerical studies on the SR −V{sub bias} for Ga{sub 0.51}In{sub 0.49}P/Ga{sub 0.99}In{sub 0.01}As/Ge triple junction solar cell. Phenomenological description was given to clarify the mechanism of operation matching point variation in SR −V{sub bias} measurements. The profile of SR−V{sub bias} curve was explained in detail by solving the coupled two-diode current-voltage characteristic transcend formula for each subcell.

  2. Optical properties of thin gold films applied to Schottky barrier solar cells

    NASA Technical Reports Server (NTRS)

    YEH Y. M.

    1974-01-01

    The Schottky barrier solar cell is considered a possible candidate for converting solar to electrical energy both for space and terrestrial applications. Knowledge of the optical constants of the ultrathin metal film used in the cell is essential for analyzing and designing higher efficiency Schottky barrier cells. The optical constants of 7.5 -nm (75-A) gold films on gallium arsenide have been obtained. In addition, the absolute collection efficiency of Schottky barrier solar cells has been determined from measured spectral response and optical constants of the gold film.

  3. New Sub-nanometer Spectral Estimates of the 0-5 nm Solar Soft X-Ray Irradiance at Mars Using the Extreme UltraViolet Monitor (EUVM) Onboard MAVEN

    NASA Astrophysics Data System (ADS)

    Thiemann, E.; Eparvier, F. G.; Chamberlin, P. C.; Woods, T. N.; Peterson, W. K.; Mitchell, D. L.; Xu, S.; Liemohn, M. W.

    2015-12-01

    characterize the effectiveness of this technique, we compare Mars atmospheric photoelectron spectral measurements made by MAVEN's Solar Wind Electron Analyzer (SWEA) against modeled photoelectron spectra which use the EUVM derived 0-5 nm solar spectrum as an input.

  4. Spectrally resolved intraband transitions on two-step photon absorption in InGaAs/GaAs quantum dot solar cell

    SciTech Connect

    Tamaki, Ryo Shoji, Yasushi; Okada, Yoshitaka; Miyano, Kenjiro

    2014-08-18

    Two-step photon absorption processes in a self-organized In{sub 0.4}Ga{sub 0.6}As/GaAs quantum dot (QD) solar cell have been investigated by monitoring the mid-infrared (IR) photoinduced modulation of the external quantum efficiency (ΔEQE) at low temperature. The first step interband and the second step intraband transitions were both spectrally resolved by scanning photon energies of visible to near-IR CW light and mid-IR pulse lasers, respectively. A peak centered at 0.20 eV corresponding to the transition to virtual bound states and a band above 0.42 eV probably due to photoexcitation to GaAs continuum states were observed in ΔEQE spectra, when the interband transition was above 1.4 eV, directly exciting wetting layers or GaAs spacer layers. On the other hand, resonant excitation of the ground state of QDs at 1.35 eV resulted in a reduction of EQE. The sign of ΔEQE below 1.40 eV changed from negative to positive by increasing the excitation intensity of the interband transition. We ascribe this to the filling of higher energy trap states.

  5. Lyman alpha SMM/UVSP absolute calibration and geocoronal correction

    NASA Technical Reports Server (NTRS)

    Fontenla, Juan M.; Reichmann, Edwin J.

    1987-01-01

    Lyman alpha observations from the Ultraviolet Spectrometer Polarimeter (UVSP) instrument of the Solar Maximum Mission (SMM) spacecraft were analyzed and provide instrumental calibration details. Specific values of the instrument quantum efficiency, Lyman alpha absolute intensity, and correction for geocoronal absorption are presented.

  6. Spectral anisotropy of subtropical deciduous forest using MISR and MODIS data acquired under large seasonal variation in solar zenith angle

    NASA Astrophysics Data System (ADS)

    Breunig, Fábio Marcelo; Galvão, Lênio Soares; dos Santos, João Roberto; Gitelson, Anatoly A.; de Moura, Yhasmin Mendes; Teles, Thiago Sousa; Gaida, William

    2015-03-01

    Recent studies in Amazonian tropical evergreen forests using the Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) have highlighted the importance of considering the view-illumination geometry in satellite data analysis. However, contrary to the observed for evergreen forests, bidirectional effects have not been evaluated in Brazilian subtropical deciduous forests. In this study, we used MISR data to characterize the reflectance and vegetation index anisotropies in subtropical deciduous forest from south Brazil under large seasonal solar zenith angle (SZA) variation and decreasing leaf area index (LAI) from the summer to winter. MODIS data were used to observe seasonal changes in the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Topographic effects on their determination were inspected by dividing data from the summer to winter and projecting results over a digital elevation model (DEM). By using the PROSAIL, we investigated the relative contribution of LAI and SZA to vegetation indices (VI) of deciduous forest. We also simulated and compared the MISR NDVI and EVI response of subtropical deciduous and tropical evergreen forests as a function of the large seasonal SZA amplitude of 33°. Results showed that the MODIS-MISR NDVI and EVI presented higher values in the summer and lower ones in the winter with decreasing LAI and increasing SZA or greater amounts of canopy shadows viewed by the sensors. In the winter, NDVI reduced local topographic effects due to the red-near infrared (NIR) band normalization. However, the contrary was observed for the three-band EVI that enhanced local variations in shaded and sunlit surfaces due to its strong dependence on the NIR band response. The reflectance anisotropy of the MISR bands increased from the summer to winter and was stronger in the backscattering direction at large view zenith angles (VZA). EVI was much more anisotropic than

  7. Radiometric calibration of optical microscopy and microspectroscopy apparata over a broad spectral range using a special thin-film luminescence standard

    SciTech Connect

    Valenta, J. Greben, M.

    2015-04-15

    Application capabilities of optical microscopes and microspectroscopes can be considerably enhanced by a proper calibration of their spectral sensitivity. We propose and demonstrate a method of relative and absolute calibration of a microspectroscope over an extraordinary broad spectral range covered by two (parallel) detection branches in visible and near-infrared spectral regions. The key point of the absolute calibration of a relative spectral sensitivity is application of the standard sample formed by a thin layer of Si nanocrystals with stable and efficient photoluminescence. The spectral PL quantum yield and the PL spatial distribution of the standard sample must be characterized by separate experiments. The absolutely calibrated microspectroscope enables to characterize spectral photon emittance of a studied object or even its luminescence quantum yield (QY) if additional knowledge about spatial distribution of emission and about excitance is available. Capabilities of the calibrated microspectroscope are demonstrated by measuring external QY of electroluminescence from a standard poly-Si solar-cell and of photoluminescence of Er-doped Si nanocrystals.

  8. 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.

  9. 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.

  10. Spectral Anisotropy of Elsässer Variables in Two-dimensional Wave-vector Space as Observed in the Fast Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Yan, Limei; He, Jiansen; Zhang, Lei; Tu, Chuanyi; Marsch, Eckart; Chen, Christopher H. K.; Wang, Xin; Wang, Linghua; Wicks, Robert T.

    2016-01-01

    Intensive studies have been conducted to understand the anisotropy of solar wind turbulence. However, the anisotropy of Elsässer variables ({{\\boldsymbol{Z}}}+/- ) in 2D wave-vector space has yet to be investigated. Here we first verify the transformation based on the projection-slice theorem between the power spectral density {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) and the spatial correlation function {{CF}}2{{D}}({r}\\parallel ,{r}\\perp ). Based on the application of the transformation to the magnetic field and the particle measurements from the WIND spacecraft, we investigate the spectral anisotropy of Elsässer variables ({{\\boldsymbol{Z}}}+/- ), and the distribution of residual energy {E}{{R}}, Alfvén ratio {R}{{A}}, and Elsässer ratio {R}{{E}} in the ({k}\\parallel ,{k}\\perp ) space. The spectra {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {\\boldsymbol{B}}, {\\boldsymbol{V}}, and {{\\boldsymbol{Z}}}{major} (the larger of {{\\boldsymbol{Z}}}+/- ) show a similar pattern that {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) is mainly distributed along a ridge inclined toward the k⊥ axis. This is probably the signature of the oblique Alfvénic fluctuations propagating outwardly. Unlike those of {\\boldsymbol{B}}, {\\boldsymbol{V}}, and {{\\boldsymbol{Z}}}{major}, the spectrum {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {{\\boldsymbol{Z}}}{minor} is distributed mainly along the k⊥ axis. Close to the k⊥ axis, | {E}{{R}}| becomes larger while {R}{{A}} becomes smaller, suggesting that the dominance of magnetic energy over kinetic energy becomes more significant at small k∥. {R}{{E}} is larger at small k∥, implying that {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {{\\boldsymbol{Z}}}{minor} is more concentrated along the k⊥ direction as compared to that of {{\\boldsymbol{Z}}}{major}. The residual energy condensate at small k∥ is consistent with simulation results in which {E}{{R}} is spontaneously generated by Alfvén wave interaction.

  11. Multispectral Photometry of the Moon and Absolute Calibration of the Clementine UV/Vis Camera

    NASA Astrophysics Data System (ADS)

    Hillier, John K.; Buratti, Bonnie J.; Hill, Kathryn

    1999-10-01

    We present a multispectral photometric study of the Moon between solar phase angles of 0 and 85°. Using Clementine images obtained between 0.4 and 1.0 μm, we produce a comprehensive study of the lunar surface containing the following results: (1) empirical photometric functions for the spectral range and viewing and illumination geometries mentioned, (2) photometric modeling that derives the physical properties of the upper regolith and includes a detailed study of the causes for the lunar opposition surge, (3) an absolute calibration of the Clementine UV/Vis camera. The calibration procedure given on the Clementine calibration web site produces reflectances relative to a halon standard and further appear significantly higher than those seen in groundbased observations. By comparing Clementine observations with prior groundbased observations of 15 sites on the Moon we have determined a good absolute calibration of the Clementine UV/Vis camera. A correction factor of 0.532 has been determined to convert the web site (www.planetary.brown.edu/clementine/calibration.html) reflectances to absolute values. From the calibrated data, we calculate empirical phase functions useful for performing photometric corrections to observations of the Moon between solar phase angles of 0 and 85° and in the spectral range 0.4 to 1.0μm. Finally, the calibrated data is used to fit a version of Hapke's photometric model modified to incorporate a new formulation, developed in this paper, of the lunar opposition surge which includes coherent backscatter. Recent studies of the lunar opposition effect have yielded contradictory results as to the mechanism responsible: shadow hiding, coherent backscatter, or both. We find that most of the surge can be explained by shadow hiding with a halfwidth of ˜8°. However, for the brightest regions (the highlands at 0.75-1.0μm) a small additional narrow component (halfwidth of <2°) of total amplitude ˜1/6 to 1/4 that of the shadow hiding surge is

  12. Dust in brown dwarfs and extra-solar planets. I. Chemical composition and spectral appearance of quasi-static cloud layers

    NASA Astrophysics Data System (ADS)

    Helling, Ch.; Woitke, P.; Thi, W.-F.

    2008-07-01

    Aims: Brown dwarfs are covered by dust cloud layers which cause inhomogeneous surface features and move below the observable τ = 1 level during the object's evolution. The cloud layers have a strong influence on the structure and spectral appearance of brown dwarfs and extra-solar planets, e.g. by providing high local opacities and by removing condensable elements from the atmosphere causing a sub-solar metalicity in the atmosphere. We aim at understanding the formation of cloud layers in quasi-static substellar atmospheres that consist of dirty grains composed of numerous small islands of different solid condensates. Methods: The time-dependent description is a kinetic model describing nucleation, growth and evaporation. It is extended to treat gravitational settling and is applied to the static-stationary case of substellar model atmospheres. From the solution of the dust moments, we determine the grain size distribution function approximately which, together with the calculated material volume fractions, provides the basis for applying effective medium theory and Mie theory to calculate the opacities of the composite dust grains. Results: The cloud particles in brown dwarfs and hot giant-gas planets are found to be small in the high atmospheric layers (a ≈ 0.01 μm), and are composed of a rich mixture of all considered condensates, in particular MgSiO3[s], Mg2SiO4[s] and SiO2[s]. As the particles settle downward, they increase in size and reach several 100 μm in the deepest layers. The more volatile parts of the grains evaporate and the particles stepwise purify to form composite particles of high-temperature condensates in the deeper layers, mainly made of Fe[s] and Al2O3[s]. The gas phase abundances of the elements involved in the dust formation process vary by orders of magnitudes throughout the atmosphere. The grain size distribution is found to be relatively broad in the upper atmospheric layers but strongly peaked in the deeper layers. This reflects

  13. Uncertainty evaluation of spectral UV irradiance measurements

    NASA Astrophysics Data System (ADS)

    Cordero, Raul R.; Seckmeyer, Gunther; Pissulla, Darius; Da Silva, Luis; Labbe, Fernando

    2008-04-01

    The reference instruments to measure the surface UV irradiance are based on a double monochromator system. The spectral irradiance yielded by these instruments is influenced by temporal instabilities and nonlinearities in the signal, the cosine error as well as uncertainties introduced in the needed prior calibrations. In this paper, we have carried out an uncertainty analysis of the spectral irradiances measured by using a mobile spectroradiometer that complies with the requirements of the Network for the Detection of Atmospheric Composition Change (NDACC). The spectral measurements were performed on 9th June 2005 (cloudless sky conditions) at the Izaña Observatory (28.3° N, 16.5° E, 2367 m above sea level, Tenerife, Spain), during an international intercomparison campaign organized in the framework of the project Quality Assurance of Spectral Ultraviolet Measurements in Europe (QASUME). At solar zenith angles smaller than 30°, we found that despite the variations due to wavelength shifts induced by the high environmental temperature the relative expanded uncertainty was about 7% in the UV-A part of the spectrum; an increment was observed at wavelengths shorter than 315 nm such that the expanded uncertainty of the UV-B irradiance at 300 nm wavelength was about 9%. The measurements of the other five teams that participated in the campaign were within the bound specified by these expanded uncertainties. We also found that, regardless of the influence of the cosine error, the uncertainties involved in the absolute calibration procedure accounted for about 65% of the irradiance uncertainty. Although only a double monochromator was used in this work, the methodology applied to evaluate the uncertainty is general and it agrees with recommendations of the ISO Guide to the Expression of Uncertainty in Measurement.

  14. Solar measurements from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.

    1994-01-01

    The analysis of the solar spectral irradiance from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite is the focus for this research grant. A pre-print copy of the paper describing the calibrations of and results from the San Marco ASSI is attached to this report. The calibration of the ASSI included (1) transfer of photometric calibration from a rocket experiment and the Solar Mesosphere Explorer (SME), (2) use of the on-board radioactive calibration sources, (3) validation of the ASSI sensitivity over its field of view, and (4) determining the degradation of the spectrometers. We have determined that the absolute values for the solar irradiance needs adjustment in the current proxy models of the solar UV irradiance, and the amount of solar variability from the proxy models are in reasonable agreement with the ASSI measurements. This research grant also has supported the development of a new solar EUV irradiance proxy model. We expected that the magnetic flux is responsible for most of the heating, via Alfen waves, in the chromosphere, transition region, and corona. From examining time series of solar irradiance data and magnetic fields at different levels, we did indeed find that the chromospheric emissions correlate best with the large magnetic field levels.

  15. Changes of solar extreme ultraviolet spectrum in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo; Huang, Jianping

    2016-07-01

    Following the extreme solar minimum during 2008 - 2009, solar activity keeps low in solar cycle 24 (SC24) and is making SC24 the weakest one of recent cycles. In this paper, we compare the solar EUV spectral irradiance between SC23 and SC24, using the measurements by the Solar EUV Experiment (SEE) on the Thermospheric Ionospheric Mesospheric Energy and Dynamics (TIMED) spacecraft. The EUV spectrum varies with solar activity, and is in general a linear function of a proxy index P= (F10.7 + F10.7A)/2. However, we find the slope of this function, i.e., the change rate of irradiance at each wavelength with P, differs between SC23 and SC24. Consequently, at a given P level, the irradiance in SC24 is higher at wavelength of 30 - 50 nm, but lower at 60 - 120 nm and longward of 140 nm; the inter-cycle variation of EUV irradiance at some wavelengths can be 30 - 40% in absolute flux. We further examine 38 most intense emission lines and find that, taking P as a reference, most of the bright coronal lines get stronger in SC24 and, by contrast, those from the chromosphere and transition region have less variability in SC24. We therefore suggest that, the empirical relation between solar EUV and P, which is derived from observations in previous solar cycles, may not adapt to SC24. The changes in EUV spectrum need to be considered in the models for aeronomic study, especially those using F10.7 index as an input parameter.

  16. Earth Observing-1 Advanced Land Imager Flight Performance Assessment: Absolute Radiometry and Stability During the First Year

    NASA Technical Reports Server (NTRS)

    Mendenhall, J. A.; Lencioni, D. E.

    2002-01-01

    The absolute radiometry of the Advanced Land Imager during the first year on orbit (November 21,2000 - November 21, 2001) is presented. Results derived from solar, lunar, ground truth, and internal reference lamp measurements are presented. An 18% drop in the radiometric response of the Band 1p data since preflight calibration at Lincoln Laboratory is observed using all techniques. This decrease cannot be accounted for by preflight calibration errors, stray light, or contamination of the focal plane. A slight drooping of the VNIR response toward the blue and a 5-12% increase in the Band 5 response is also apparent in all the data. Radiometric response correction factors have been calculated and preflight calibration coefficients have been updated in order to provide +/- 5% agreement between the measured solar, lunar, and ground truth data and the expected values. The radiometric stability of the ALI during the first year of operation is also presented for each spectral band. Internal reference lamp data indicate the focal plane has been stable to within 1% for bands 1p, 1, 2, 5p, 5, 7, pan and 3% for Bands 3,4, 4p since launch. Solar, lunar, and ground truth measurements indicate the optical train and solar diffuser of the instrument has been stable to within 1% since initial measurements on orbit in late December 2000.

  17. 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.

  18. THE INFRARED TELESCOPE FACILITY (IRTF) SPECTRAL LIBRARY: COOL STARS

    SciTech Connect

    Rayner, John T.; Cushing, Michael C.; Vacca, William D. E-mail: michael.cushing@gmail.com

    2009-12-01

    We present a 0.8-5 {mu}m spectral library of 210 cool stars observed at a resolving power of R {identical_to} {lambda}/{delta}{lambda} {approx} 2000 with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The stars have well-established MK spectral classifications and are mostly restricted to near-solar metallicities. The sample not only contains the F, G, K, and M spectral types with luminosity classes between I and V, but also includes some AGB, carbon, and S stars. In contrast to some other spectral libraries, the continuum shape of the spectra is measured and preserved in the data reduction process. The spectra are absolutely flux calibrated using the Two Micron All Sky Survey photometry. Potential uses of the library include studying the physics of cool stars, classifying and studying embedded young clusters and optically obscured regions of the Galaxy, evolutionary population synthesis to study unresolved stellar populations in optically obscured regions of galaxies and synthetic photometry. The library is available in digital form from the IRTF Web site.

  19. 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.

  20. The role of the Fraunhofer lines in solar brightness variability

    NASA Astrophysics Data System (ADS)

    Shapiro, A. I.; Solanki, S. K.; Krivova, N. A.; Tagirov, R. V.; Schmutz, W. K.

    2015-09-01

    Context. The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. Aims: We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Methods: Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and wavelength. By consecutive elimination of molecular and atomic lines from the radiative transfer calculations, we assessed the role of these lines in producing solar brightness variability. Results: We show that the variations in Fraunhofer lines define the amplitude of the solar brightness variability on timescales greater than a day and even the phase of the total solar irradiance variability over the 11-year cycle. We also demonstrate that molecular lines make substantial contribution to solar brightness variability on the 11-year activity cycle and centennial timescales. In particular, our model indicates that roughly a quarter of the total solar irradiance variability over the 11-year cycle originates in molecular lines. The maximum of the absolute spectral brightness variability on timescales greater than a day is associated with the CN violet system between 380 and 390 nm.

  1. 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.

  2. 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.

  3. Measuring the solar atmosphere

    NASA Astrophysics Data System (ADS)

    de la Cruz Rodriguez, Jaime

    2010-11-01

    The new CRISP filter at the Swedish 1-m Solar Telescope provides opportunities for observing the solar atmosphere with unprecedented spatial resolution and cadence. In order to benefit from the high quality of observational data from this instrument, we have developed methods for calibrating and restoring polarized Stokes images, obtained at optical and near infrared wavelengths, taking into account field-of-view variations of the filter properties. In order to facilitate velocity measurements, a time series from a 3D hydrodynamical granulation simulation is used to compute quiet Sun spectral line profiles at different heliocentric angles. The synthetic line profiles, with their convective blueshifts, can be used as absolute references for line-of-sight velocities. Observations of the Ca II 8542 Å line are used to study magnetic fields in chromospheric fibrils. The line wings show the granulation pattern at mid-photospheric heights whereas the overlying chromosphere is seen in the core of the line. Using full Stokes data, we have attempted to observationally verify the alignment of chromospheric fibrils with the magnetic field. Our results suggest that in most cases fibrils are aligned along the magnetic field direction, but we also find examples where this is not the case. Detailed interpretation of Stokes data from spectral lines formed in the chromospheric data can be made using non-LTE inversion codes. For the first time, we use a realistic 3D MHD chromospheric simulation of the quiet Sun to assess how well NLTE inversions recover physical quantities from spectropolarimetric observations of Ca II 8542 Å. We demonstrate that inversions provide realistic estimates of depth-averaged quantities in the chromosphere, although high spectral resolution and high sensitivity are needed to measure quiet Sun chromospheric magnetic fields.

  4. 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)

  5. 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.-

  6. High Efficiency Near Infrared Spectrometer for Zodiacal Light Spectral Study

    NASA Technical Reports Server (NTRS)

    Kutyrea, A. S.

    2008-01-01

    We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 61 2, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I lneat 5 184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

  7. Comparison of two methods for short circuit current measurement of large size solar cell

    NASA Astrophysics Data System (ADS)

    Huang, Xuebo; Quan, Chenggen; Kng, Jerald

    2015-07-01

    The differential spectral responsivity (DSR) measurement and the solar simulator based current to voltage characterisation methods are two accurate methods for measuring the short circuit current, a critical parameter, of a solar cell under standard testing conditions. For the calibration of World Photovoltaic Scale (WPVS) reference solar cell with small size (20 mm x 20 mm), the measurement results using these two methods are agreed well within 1%. But for the calibration of large size (e.g. 156 mm x 156 mm) of solar cell, the measurement results using two methods are not agreed well and their deviation could be more than 10 %. In DSR method, the short circuit current of a solar cell is determined through measuring its relative irradiance spectral responsivity in spectral range from 280 nm to 1200 nm and its absolute irradiance responsivity at wavelength of 650 nm by reference standard photodiodes. As the detective area of large size solar cell (detective area: 156 mm x 156 mm) is much bigger than that of standard photodiodes (detective area: 12.56 mm2), the spatial uniformity of irradiance of modulated monochromatic probe beam on the test solar cell and the standard photodiode is critical for calculation of absolute irradiance responsivity of the test solar cell. The correction for the calculation must be done according to the measured spatial uniformity of probe beam and the detective areas of the test solar cell and standard photodiodes. The experiment showed the correction factor and its uncertainty are smaller if the detective areas difference between the test solar cell and the standard is smaller. Based on this observation, a standard solar cell (detective area: 20 mm x 20 mm) instead of standard photodiodes was used to calibrate absolute irradiance responsivity of the test solar cell (detective area: 156 mm x 156 mm) at wavelength of 650 nm. After such improvement, measurement results using two different methods agree well about 3 % for the large size

  8. Modeling Polarized Solar Radiation from Various Scene Types for Satellite Remote-Sensing Applications

    NASA Astrophysics Data System (ADS)

    Sun, W.

    2015-12-01

    To correct the polarization-induced errors in measured reflected solar spectra, the polarization state of the reflected solar light must be known. In this presentation, recent modeling of the polarized solar radiation from the ocean, desert, forest, and clouds is reported. The modeled polarized solar radiation quantities are compared with the PARASOL satellite measurements for various scene types. A novel super-thin cloud optical depth (OD) retrieval method based on polarization measurement is also introduced. This study provides a reliable approach for making the spectral Polarization Distribution Models (PDMs) for satellite inter-calibration applications of NASA's future Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. This study also reports the advance in developing a technique to retrieve super-thin clouds with OD < ~0.3, which are missed by passive satellite sensors like the MODIS. Key words: Reflected solar radiation, polarization, correction of satellite data, retrieval of super-thin clouds.

  9. 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.

  10. Solar imaging vector magnetograph

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.

    1993-01-01

    This report describes an instrument which has been constructed at the University of Hawaii to make observations of the magnetic field in solar active regions. Detailed knowledge of active region magnetic structures is crucial to understanding many solar phenomena, because the magnetic field both defines the morphology of structures seen in the solar atmosphere and is the apparent energy source for solar flares. The new vector magnetograph was conceived in response to a perceived discrepancy between the capabilities of X ray imaging telescopes to be operating during the current solar maximum and those of existing magnetographs. There were no space-based magnetographs planned for this period; the existing ground-based instruments variously suffered from lack of sensitivity, poor time resolution, inadequate spatial resolution or unreliable sites. Yet the studies of flares and their relationship to the solar corona planned for the 1991-1994 maximum absolutely required high quality vector magnetic field measurements. By 'vector' measurements we mean that the observation attempts to deduce the complete strength and direction of the field at the measurement site, rather than just the line of sight component as obtained by a traditional longitudinal magnetograph. Knowledge of the vector field permits one to calculate photospheric electric currents, which might play a part in heating the corona, and to calculate energy stored in coronal magnetic fields as the result of such currents. Information about the strength and direction of magnetic fields in the solar atmosphere can be obtained in a number of ways, but quantitative data is best obtained by observing Zeeman-effect polarization in solar spectral lines. The technique requires measuring the complete state of polarization at one or more wavelengths within a magnetically sensitive line of the solar spectrum. This measurement must be done for each independent spatial point for which one wants magnetic field data. All the

  11. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. A rare gas optics-free absolute photon flux and energy analyzer to provide absolute photoionization rates of inflowing interstellar neutrals

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    A prototype spectrometer has been developed for space applications requiring long term absolute EUV photon flux measurements. The energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  19. 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.

  20. Wavelength variation of p-mode intensity fluctuations. [in solar photosphere and low chromosphere

    NASA Technical Reports Server (NTRS)

    Ronan, R. S.; Harvey, J. W.; Duvall, T. L, Jr.

    1991-01-01

    The oscillatory signal in the solar p-mode band has been measured as a function of optical wavelength using a grating spectrometer and Fourier transform spectrometer. The relative intensity fluctuations are found to increase with height in the solar photosphere, while the absolute level of intensity fluctuations in the p-mode band is reduced by about 50 percent in the cores and wings of Ca II H and K, H-delta, and H-gamma compared to the neighboring spectral regions. Thus, these spectral regions of diminished absolute p-mode signal could be exploited as signal references by spectrophotometers while attempting to observe nonradial p-mode oscillations in stars from the ground. High spectral and temporal resolution observations of several unblended lines in the red portion of the visible spectrum show an asymmetry in the relative and absolute p-mode intensity oscillations across the line profiles. The peak in intensity oscillations lies in the blue wing of the lines.

  1. 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.

  2. 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

  3. Airborne spectral radiometry for crop health and yield estimation

    NASA Astrophysics Data System (ADS)

    O'Mongain, Eon; Green, S. E.; Walsh, James E.; Burke, J.

    1995-01-01

    Spectral reflectance measurements have been made over sugar beet crops from a helicopter during 1991, 1992, and 1993 using a portable multichannel spectrometer system. In 1994 the studies were extended to demonstrate the potential for the measurement of stress in other crops. The observations are made from an altitude of about 150 m over the spectral range 420 nm to 810 nm, with a bandwidth of 5 nm. Downwelling solar irradiance and upwelling reflected irradiance are monitored by the multichannel spectrometer simultaneously. Both the absolute values of the reflectance at each wavelength and the variance of these reflectance values across each plot are shown to be related to the state of the crop. Concurrent agricultural ground truth consisting of fresh leaf weight and dry matter accumulation, is used in defining the crop yield models. The study aims to determine the appropriate radiometrically derived parameters which could be used as alternative model inputs. Although significant spectral differences exist and can be extracted by conventional band ratio or singular value decomposition techniques, the variance in the samples of ground truth data constrain the ability to define meaningful radiometric parameters. Improved experimental procedures are proposed.

  4. 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.

  5. Spectral response measurements with white light bias

    NASA Technical Reports Server (NTRS)

    Devaney, W.; Lorenz, S.; Meakin, J. D.

    1976-01-01

    The spectral response of solar cells such as the CdS/Cu2S cell is non-linear with distinct quenching and enhancement bands. One possible technique to produce standardized solar efficiencies is to fold in spectral response with a standard solar spectrum. The spectral response of a cell was measured in a way which matched cell behavior under white light illumination. A technique was developed to measure the response of a cell to low intensity chopped monochromatic light while the cell is also illuminated with a white light bias corresponding to AMI.

  6. Spectral analysis of the effects of 1.7 MeV electron irradiation on the current transfer characteristic of cadmium telluride solar cells.

    PubMed

    Tian, Jin-Xiu; Zeng, Guang-Gen; He, Xu-Lin; Zhang, Jing-Quan; Wu, Li-Li; Li, Wei; Li, Bing; Wang, Wen-Wu; Feng, Liang-Huan

    2014-04-01

    The effects of device performance of 1.7 MeV electron irradiation on cadmium telluride polycrystalline thin film solar cells with the structure of anti-radiation glass/ITO/ZnO/CdS/CdTe/ZnTe/ZnTe : Cu/Ni have been studied. Light and dark I-V characteristics, dark C-V characteristics, quantum efficiency (QE), admittance spectrum (AS) and other testing methods were used to analyze cells performance such as the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (eta). It was explored to find out the effects of irradiation on the current transfer characteristic of solar cells combined with the dark current density (Jo), diode ideal factor (A), quantum efficiency, carrier concentration and the depletion layer width. The decline in short-circuit current was very large and the efficiency of solar cells decreased obviously after irradiation. Reverse saturation current density increased, which indicates that p-n junction characteristics of solar cells were damaged, and diode ideal factor was almost the same, so current transport mechanism of solar cells has not changed. Quantum efficiency curves proved that the damage of solar cells' p-n junction influenced the collection of photo-generated carriers. Irradiation made carrier concentration reduce to 40.6%. The analyses have shown that. A new defect was induced by electron irradiation, whose position is close to 0.58 eV above the valence band in the forbidden band, and capture cross section is 1.78 x 10(-16) cm2. These results indicate that irradiation influences the generation of photo-generated carriers, increases the risk of the carrier recombination and the reverse dark current, and eventually makes the short-circuit current of solar cells decay.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  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. Absolute limit on rotation of gravitationally bound stars

    NASA Astrophysics Data System (ADS)

    Glendenning, N. K.

    1994-03-01

    The authors seek an absolute limit on the rotational period for a neutron star as a function of its mass, based on the minimal constraints imposed by Einstein's theory of relativity, Le Chatelier's principle, causality, and a low-density equation of state, uncertainties which can be evaluated as to their effect on the result. This establishes a limiting curve in the mass-period plane below which no pulsar that is a neutron star can lie. For example, the minimum possible Kepler period, which is an absolute limit on rotation below which mass-shedding would occur, is 0.33 ms for a M = 1.442 solar mass neutron star (the mass of PSR1913+16). If the limit were found to be broken by any pulsar, it would signal that the confined hadronic phase of ordinary nucleons and nuclei is only metastable.

  1. 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.

  2. On the absolute calibration of SO2 cameras

    NASA Astrophysics Data System (ADS)

    Lübcke, P.; Bobrowski, N.; Illing, S.; Kern, C.; Alvarez Nieves, J. M.; Vogel, L.; Zielcke, J.; Delgado Granados, H.; Platt, U.

    2012-09-01

    Sulphur dioxide emission flux measurements are an important tool for volcanic monitoring and eruption risk assessment. The SO2 camera technique remotely measures volcanic emissions by analysing the ultraviolet absorption of SO2 in a narrow spectral window between 305 nm and 320 nm using solar radiation scattered in the atmosphere. The SO2 absorption is selectively detected by mounting band-pass interference filters in front of a two-dimensional, UV-sensitive CCD detector. While this approach is simple and delivers valuable insights into the two-dimensional SO2 distribution, absolute calibration has proven to be difficult. An accurate calibration of the SO2 camera (i.e., conversion from optical density to SO2 column density, CD) is crucial to obtain correct SO2 CDs and flux measurements that are comparable to other measurement techniques and can be used for volcanological applications. The most common approach for calibrating SO2 camera measurements is based on inserting quartz cells (cuvettes) containing known amounts of SO2 into the light path. It has been found, however, that reflections from the windows of the calibration cell can considerably affect the signal measured by the camera. Another possibility for calibration relies on performing simultaneous measurements in a small area of the camera's field-of-view (FOV) by a narrow-field-of-view Differential Optical Absorption Spectroscopy (NFOV-DOAS) system. This procedure combines the very good spatial and temporal resolution of the SO2 camera technique with the more accurate column densities obtainable from DOAS measurements. This work investigates the uncertainty of results gained through the two commonly used, but quite different calibration methods (DOAS and calibration cells). Measurements with three different instruments, an SO2 camera, a NFOV-DOAS system and an Imaging DOAS (IDOAS), are presented. We compare the calibration-cell approach with the calibration from the NFOV-DOAS system. The respective

  3. 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

  4. Traceability of solar UV measurements using the Qasume reference spectroradiometer.

    PubMed

    Hülsen, Gregor; Gröbner, Julian; Nevas, Saulius; Sperfeld, Peter; Egli, Luca; Porrovecchio, Geiland; Smid, Marek

    2016-09-10

    One major objective of the European Joint Research Project "Traceability for surface spectral solar ultraviolet (UV) radiation" was to reduce the uncertainty of spectral UV measurements. The measurement instrument used for this work was the portable UV European reference spectroradiometer Qasume. The calibration uncertainty of this instrument was decreased and validated by a comparison of direct calibrations against a primary standard for spectral irradiance, a high temperature blackbody radiator, and against a reference detector using a spectrally tunable laser as a monochromatic source. The spectral irradiance responsivity of the reference detector is traceable to the primary standard of optical power, realized through a cryogenic radiometer, and to the SI unit of meter. The measuring technique was improved by the construction of a new reference spectroradiometer, QasumeII. An improved input optics removes the dependences of the measured solar irradiance on the angle of incident for solar zenith angle smaller than 75 deg. Moreover, a hybrid photon detection system enables continuous tracking of the instrument's responsivity changes. For both spectroradiometer systems an uncertainty budget was calculated. The improvements have reduced the measurement uncertainties of solar spectral UV irradiance measurements from 4.8% in 2005 to 2.0% (k=2) in the spectral region above 310 nm. The largest sources of uncertainty were the absolute spectral irradiance responsivity calibration, the angular response uncertainty, and the instrument stability using the hybrid detector, which were reduced from 3.6% to 1.1%, from 1.2% to 0.6%, and from 0.65% to 0.4%, with respect to the situation prior to the project. The new instrument was validated during a four month intercomparison relative to the Qasume reference. The mean ratio of the solar irradiance scans between the two reference spectroradiometers has an offset of +0.7% and a standard deviation of ±1.5% for a wavelength greater

  5. Traceability of solar UV measurements using the Qasume reference spectroradiometer.

    PubMed

    Hülsen, Gregor; Gröbner, Julian; Nevas, Saulius; Sperfeld, Peter; Egli, Luca; Porrovecchio, Geiland; Smid, Marek

    2016-09-10

    One major objective of the European Joint Research Project "Traceability for surface spectral solar ultraviolet (UV) radiation" was to reduce the uncertainty of spectral UV measurements. The measurement instrument used for this work was the portable UV European reference spectroradiometer Qasume. The calibration uncertainty of this instrument was decreased and validated by a comparison of direct calibrations against a primary standard for spectral irradiance, a high temperature blackbody radiator, and against a reference detector using a spectrally tunable laser as a monochromatic source. The spectral irradiance responsivity of the reference detector is traceable to the primary standard of optical power, realized through a cryogenic radiometer, and to the SI unit of meter. The measuring technique was improved by the construction of a new reference spectroradiometer, QasumeII. An improved input optics removes the dependences of the measured solar irradiance on the angle of incident for solar zenith angle smaller than 75 deg. Moreover, a hybrid photon detection system enables continuous tracking of the instrument's responsivity changes. For both spectroradiometer systems an uncertainty budget was calculated. The improvements have reduced the measurement uncertainties of solar spectral UV irradiance measurements from 4.8% in 2005 to 2.0% (k=2) in the spectral region above 310 nm. The largest sources of uncertainty were the absolute spectral irradiance responsivity calibration, the angular response uncertainty, and the instrument stability using the hybrid detector, which were reduced from 3.6% to 1.1%, from 1.2% to 0.6%, and from 0.65% to 0.4%, with respect to the situation prior to the project. The new instrument was validated during a four month intercomparison relative to the Qasume reference. The mean ratio of the solar irradiance scans between the two reference spectroradiometers has an offset of +0.7% and a standard deviation of ±1.5% for a wavelength greater

  6. 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.

  7. Electrodynamic System of Earth in Moon and Solar Tides Investigation

    NASA Astrophysics Data System (ADS)

    Grunskaya, Lubov; Isakevich, Valiriy

    Since 2000 there has been working the united system of monitoring of electrical and geomagnetic fields of ELF range of the atmosphere boundary surface layer at the spaced apart stations: Vladimir State physical experimental ground; the station of RAS Institute of Sun and Earth physics at Lake Baikal; the station in Paratunka (Kamchatka); the station in Obninsk. There has been developed a programme-analytical system (PAS) to investigate signal structures in spectral and time series, caused by geophysical and astrophysical processes based on the method of eigen vectors. There has been developed a programme and analytical system to investigate the signal structure in the spectral and time series caused by geophysical processes. There has been estimated the amplitude and investigated the properties of the Earth atmosphere boundary layer electrical field components localized spectrally at the frequencies of the moon and solar tides. There has been exposed a method of determination of relative and absolute amplitudes of the main components of the eigen series. There has been investigated coherence of the spectral components at the frequencies of solar and moon tides. The work is carried out with supporting of RFFI № 14-07-97510, State Task to Universities on 2014-2016.

  8. Absolute properties of the triple star HP Aurigae

    SciTech Connect

    Lacy, Claud H. Sandberg; Burks, Charles L.; Torres, Guillermo; Wolf, Marek E-mail: clburks@email.uark.edu E-mail: wolf@cesnet.cz

    2014-01-01

    New photometric, spectroscopic, and eclipse timing observations of the eclipsing binary star HP Aur allow for very accurate orbital determinations, even in the presence of a third body and transient starspot activity. The eclipsing binary masses are determined to an accuracy of ±0.4% and the radii to ±0.6%. The masses are 0.9543 ± 0.0041 and 0.8094 ± 0.0036 solar masses, and the radii are 1.0278 ± 0.0042 and 0.7758 ± 0.0034 solar radii, respectively. The orbital period in the outer orbit is accurately determined for the first time: 4.332 ± 0.011 yr. A comparison with current theories of stellar evolution shows that the components' absolute properties can be well-matched by the current models at an age of about 7 billion years.

  9. Absolute properties of the eclipsing binary star IM Persei

    SciTech Connect

    Lacy, Claud H. Sandberg; Torres, Guillermo; Fekel, Francis C.; Muterspaugh, Matthew W.; Southworth, John E-mail: gtorres@cfa.harvard.edu E-mail: matthew1@coe.tsuniv.edu

    2015-01-01

    IM Per is a detached A7 eccentric eclipsing binary star. We have obtained extensive measurements of the light curve (28,225 differential magnitude observations) and radial velocity curve (81 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.7831 ± 0.0094 and 1.7741 ± 0.0097 solar masses, and radii of 2.409 ± 0.018 and 2.366 ± 0.017 solar radii. The orbital period is 2.25422694(15) days and the eccentricity is 0.0473(26). A faint third component was detected in the analysis of the light curves, and also directly observed in the spectra. The observed rate of apsidal motion is consistent with theory (U = 151.4 ± 8.4 year). We determine a distance to the system of 566 ± 46 pc.

  10. Water frost and ice - The near-infrared spectral reflectance 0.65-2.5 microns. [observed on natural satellites and other solar system objects

    NASA Technical Reports Server (NTRS)

    Clark, R. N.

    1981-01-01

    The spectral reflectance of water frost and frost on ice as a function of temperature and grain size is presented with 1-1/2% spectral resolution in the 0.65- to 2.5-micron wavelength region. The well-known 2.0-, 1.65-, and 1.5-micron solid water absorption bands are precisely defined along with the little studied 1.25-micron band and the previously unidentified (in reflectance) 1.04-, 0.90-, and 0.81-micron absorption bands. The 1.5-microns band complex is quantitatively analyzed using a nonlinear least squares algorithm to resolve the band into four Gaussian components as a function of grain size and temperature. It is found that the 1.65-micron component, which was thought to be a good temperature sensor, is highly grain-size dependent and poorly suited to temperature sensing. Another Gaussian component appears to show a dependence of width on grain size while being independent of temperature. The relative apparent band depths are different for frost layers on ice than for thick layers of frost and may explain the apparent band depths seen in many planetary reflectance spectra.

  11. Multi-decade Measurements of the Long-Term Trends of Atmospheric Species by High-Spectral-Resolution Infrared Solar Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Chiou, Linda; Goldman, Aaron; Hannigan, James W.

    2010-01-01

    Solar absorption spectra were recorded for the first time in 5 years with the McMath Fourier transform spectrometer at the US National solar Observatory on Kitt Peak in southern Arizona, USA (31.91 N latitude, 111.61 W longitude, 2.09 km altitude). The solar absorption spectra cover 750-1300 and 1850-5000 cm(sup -1) and were recorded on 20 days during March-June 2009. The measurements mark the continuation of a long-term record of atmospheric chemical composition measurements that have been used to quantify seasonal cycles and long-term trends of both tropospheric and stratospheric species from observations that began i 1977. Fits to the measured spectra have been performed, and they indicate the spectra obtained since return to operational status are nearly free of channeling and the instrument line shape function is well reproduced taking into account the measurement parameters. We report updated time series measurements of total columns for six atmospheric species and their analysis for seasonal cycles and long-term trends. An sn example, the time series fit shows a decrease in the annual increase rate i Montreal-Protocol-regulated chlorofluorocarbon CCL2F2 from 1.51 plus or minus 0.38% yr(sup -1) at the beginning of the time span to -1.54 plus or minus 1.28 yr(sup -1) at the end of the time span, 1 sigma, and hence provides evidence for the impact of those regulations on the trend.

  12. Spectral reflectance data of a high temperature stable solar selective coating based on MoSi2 -Si3N4.

    PubMed

    Hernández-Pinilla, D; Rodríguez-Palomo, A; Álvarez-Fraga, L; Céspedes, E; Prieto, J E; Muñoz-Martín, A; Prieto, C

    2016-06-01

    Data of optical performance, thermal stability a