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Sample records for diffuse solar radiation

  1. Influence of Diffused Solar Radiation on the Solar Concentrating System of a Plant Shoot Configuration

    NASA Astrophysics Data System (ADS)

    Obara, Shin'ya

    Investigation of a plant shoot configuration is used to obtain valuable information concerning the received light system. Additionally, analysis results concerning a plant shoot configuration interaction with direct solar radiation were taken from a past study. However, in order to consider a plant shoot as a received sunlight system, it is necessary to understand the received light characteristics of both direct solar radiation and diffused solar radiation. Under a clear sky, the ratio of direct solar radiation to diffused solar radiation is large. However, under a clouded sky, the amount of diffused solar radiation becomes larger. Therefore, in this paper, we investigate the received light characteristics of a plant shoot configuration under the influence of diffused solar radiation. As a result, we clarify the relationship between the amount of diffused solar radiation and the amount of received light as a function of the characteristics of the plant shoot configuration. In order to obtain diffused solar radiation, it is necessary to correspond to the radiation of the multi-directions. In the analysis, the characteristic of the difference in arrangement of the top leaf and the other leaf was obtained. Therefore, in analysis, leaves other than the top were distributed in the wide range.

  2. Diffuse solar radiation and associated meteorological parameters in India

    NASA Astrophysics Data System (ADS)

    Bhattacharya, A. B.; Kar, S. K.; Bhattacharya, R.

    1996-10-01

    Solar diffuse radiation data including global radiation, shortwave and longwave balances, net radiation and sunshine hours have been extensively analyzed to study the variation of diffuse radiation with turbidity and cloud discharges appearing in the form of atmospherics over the tropics. Results of surface radiation measurements at Calcutta, Poona, Delhi and Madras are presented together with some meteorological parameters. The monthly values of diffuse radiation and the monthly ratios of diffuse to global solar radiation have been examined, with a special emphasis in relation to the noise level of atmospherics at Calcutta in the very low frequency band. The results exhibit some definite seasonal changes which appear to be in close agreement with one another. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->

  3. Understanding Coupling of Global and Diffuse Solar Radiation with Climatic Variability

    NASA Astrophysics Data System (ADS)

    Hamdan, Lubna

    Global solar radiation data is very important for wide variety of applications and scientific studies. However, this data is not readily available because of the cost of measuring equipment and the tedious maintenance and calibration requirements. Wide variety of models have been introduced by researchers to estimate and/or predict the global solar radiations and its components (direct and diffuse radiation) using other readily obtainable atmospheric parameters. The goal of this research is to understand the coupling of global and diffuse solar radiation with climatic variability, by investigating the relationships between these radiations and atmospheric parameters. For this purpose, we applied multilinear regression analysis on the data of National Solar Radiation Database 1991--2010 Update. The analysis showed that the main atmospheric parameters that affect the amount of global radiation received on earth's surface are cloud cover and relative humidity. Global radiation correlates negatively with both variables. Linear models are excellent approximations for the relationship between atmospheric parameters and global radiation. A linear model with the predictors total cloud cover, relative humidity, and extraterrestrial radiation is able to explain around 98% of the variability in global radiation. For diffuse radiation, the analysis showed that the main atmospheric parameters that affect the amount received on earth's surface are cloud cover and aerosol optical depth. Diffuse radiation correlates positively with both variables. Linear models are very good approximations for the relationship between atmospheric parameters and diffuse radiation. A linear model with the predictors total cloud cover, aerosol optical depth, and extraterrestrial radiation is able to explain around 91% of the variability in diffuse radiation. Prediction analysis showed that the linear models we fitted were able to predict diffuse radiation with efficiency of test adjusted R2 values

  4. Diffuse radiation

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.

  5. Modeling Suomi-NPP VIIRS Solar Diffuser Degradation due to Space Radiation

    NASA Astrophysics Data System (ADS)

    Shao, X.; Cao, C.

    2014-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP uses a solar diffuser (SD) as on-board radiometric calibrator for the reflective solar band (RSB) calibration. Solar diffuser is made of Spectralon (one type of fluoropolymer) and was chosen because of its controlled reflectance in the VIS-NIR-SWIR region and its near-Lambertian reflectance profile. Spectralon is known to degrade in reflectance at the blue end of the spectrum due to exposure to space radiations such as solar UV radiation and energetic protons. These space radiations can modify the Spectralon surface through breaking C-C and C-F bonds and scissioning or cross linking the polymer, which causes the surface roughness and degrades its reflectance. VIIRS uses a SDSM (Solar Diffuser Stability Monitor) to monitor the change in the Solar Diffuser reflectance in the 0.4 - 0.94 um wavelength range and provide a correction to the calibration constants. The H factor derived from SDSM reveals that reflectance of 0.4 to 0.6um channels of VIIRS degrades faster than the reflectance of longer wavelength RSB channels. A model is developed to derive characteristic parameters such as mean SD surface roughness height and autocovariance length of SD surface roughness from the long term spectral degradation of SD reflectance as monitored by SDSM. These two parameters are trended to assess development of surface roughness of the SD over the operation period of VIIRS.

  6. Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

    1987-01-01

    Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

  7. Building global and diffuse solar radiation series and assessing decadal trends in Girona (NE Iberian Peninsula)

    NASA Astrophysics Data System (ADS)

    Calbó, Josep; González, Josep-Abel; Sanchez-Lorenzo, Arturo

    2016-05-01

    Measurement of solar radiation was initiated in Girona, northeast of the Iberian Peninsula, in the late 1980s. Initially, two pyranometers were installed, one of them equipped with a shadowband for measuring the diffuse component. Two other pyranometers currently exist, both ventilated and one of them shadowed, with a sphere, and a pyrheliometer for measuring direct radiation. Additional instruments for other shortwave and longwave components, clouds, and atmospheric aerosols have been installed in recent years. The station is subject to daily inspection, data are saved at high temporal resolution, and instruments are periodically calibrated, all in accordance with the directions of the Baseline Surface Radiation Network. The present paper describes how the entire series of global solar radiation (1987-2014) and diffuse radiation (1994-2014) were built, including the quality control process. Appropriate corrections to the diffuse component were made when a shadowband was employed to make measurements. Analysis of the series reveals that annual mean global irradiance presents a statistically significant increase of 2.5 W m-2 (1.4 %) decade-1 (1988-2014 period), mainly due to what occurs in summer (5.6 W m-2 decade-1). These results constitute the first assessment of solar radiation trends for the northeastern region of the Iberian Peninsula and are consistent with trends observed in the regional surroundings and also by satellite platforms, in agreement with the global brightening phenomenon. Diffuse radiation has decreased at -1.3 W m-2 (-2 %) decade-1 (1994-2014 period), which is a further indication of the reduced cloudiness and/or aerosol load causing the changes.

  8. Effects of Radiative Diffusion on Thin Flux Tubes in Turbulent Solar-like Convection

    NASA Astrophysics Data System (ADS)

    Weber, M. A.; Fan, Y.

    2015-05-01

    We study the combined effects of convection and radiative diffusion on the evolution of thin magnetic flux tubes in the solar interior. Radiative diffusion is the primary supplier of heat to convective motions in the lower convection zone, and it results in a heat input per unit volume of magnetic flux tubes that has been ignored by many previous thin flux tube studies. We use a thin flux tube model subject to convection taken from a rotating spherical shell of turbulent, solar-like convection as described by Weber, Fan, and Miesch ( Astrophys. J. 741, 11, 2011; Solar Phys. 287, 239, 2013), now taking into account the influence of radiative heating on 1022 Mx flux tubes, corresponding to flux tubes of large active regions. Our simulations show that flux tubes of ≤ 60 kG that are subject to solar-like convective flows do not anchor in the overshoot region, but rather drift upward because of the increased buoyancy of the flux tube earlier in its evolution, which results from including radiative diffusion. Flux tubes of magnetic field strengths ranging from 15 kG to 100 kG have rise times of ≤ 0.2 years and exhibit a Joy's Law tilt-angle trend. Our results suggest that radiative heating is an effective mechanism by which flux tubes can escape from the stably stratified overshoot region. Moreover, flux tubes do not necessarily need to be anchored in the overshoot region to produce emergence properties similar to those of active regions on the Sun.

  9. An anisotropic model of diffuse solar radiation with application to an optimization of compound parabolic collectors

    NASA Astrophysics Data System (ADS)

    Perez, R. R.

    Based on a simple geometrical description of the sky hemisphere and the magnitude of the horizontal diffuse radiation, a model for estimating diffuse radiation impinging on sloping surfaces was developed. Tests against data show that substantial improvement is achieved over the classical isotropic model for any collector slope or orientation. Improvement is found for instantaneous as well as accumulated data. The application of the model to compound parabolic collectors (CPC) accounts partly for the role played by forward scattered radiation in the total energy they receive. An optimization of CPC's geometrical characteristics is performed for photovoltaic generation in the area of Albany, NY. This calculation is used to assess the relative effects of meteorological conditions and economic assumptions or optimum concentration values, and provides the reader with information pertaining to the variation of the cost of electrical energy produced as a function of the cost of silicon solar cells.

  10. Radiative heating of interstellar grains falling toward the solar nebula: 1-D diffusion calculations.

    PubMed

    Simonelli, D P; Pollack, J B; McKay, C P

    1997-02-01

    As the dense molecular cloud that was the precursor of our Solar System was collapsing to form a protosun and the surrounding solar-nebula accretion disk, infalling interstellar grains were heated much more effectively by radiation from the forming protosun than by radiation from the disk's accretion shock. Accordingly, we have estimated the temperatures experienced by these infalling grains using radiative diffusion calculations whose sole energy source is radiation from the protosun. Although the calculations are 1-dimensional, they make use of 2-D, cylindrically symmetric models of the density structure of a collapsing, rotating cloud. The temperature calculations also utilize recent models for the composition and radiative properties of interstellar grains (Pollack et al. 1994. Astrophys. J. 421, 615-639), thereby allowing us to estimate which grain species might have survived, intact, to the disk accretion shock and what accretion rates and molecular-cloud rotation rates aid that survival. Not surprisingly, we find that the large uncertainties in the free parameter values allow a wide range of grain-survival results: (1) For physically plausible high accretion rates or low rotation rates (which produce small accretion disks), all of the infalling grain species, even the refractory silicates and iron, will vaporize in the protosun's radiation field before reaching the disk accretion shock. (2) For equally plausible low accretion rates or high rotation rates (which produce large accretion disks), all non-ice species, even volatile organics, will survive intact to the disk accretion shock. These grain-survival conclusions are subject to several limitations which need to be addressed by future, more sophisticated radiative-transfer models. Nevertheless, our results can serve as useful inputs to models of the processing that interstellar grains undergo at the solar nebula's accretion shock, and thus help address the broader question of interstellar inheritance in

  11. Experimental measurements of a prototype high concentration Fresnel lens CPV module for the harvesting of diffuse solar radiation.

    PubMed

    Yamada, Noboru; Okamoto, Kazuya

    2014-01-13

    A prototype concentrator photovoltaic (CPV) module with high solar concentration, an added low-cost solar cell, and an adjoining multi-junction solar cell is fabricated and experimentally demonstrated. In the present CPV module, the low cost solar cell captures diffuse solar radiation penetrating the concentrator lens and the multi-junction cell captures concentrated direct solar radiation. On-sun test results show that the electricity generated by a Fresnel lens-based CPV module with an additional crystalline silicon solar cell is greater than that for a conventional CPV module by a factor of 1.44 when the mean ratio of diffuse normal irradiation to global normal irradiation at the module aperture is 0.4. Several fundamental optical characteristics are presented for the present module.

  12. Solar UV-B in tropical forest gaps: Analysis using direct and diffuse radiation

    SciTech Connect

    Flint, S.D.; Caldwell, M.M.

    1995-06-01

    Experiments with natural levels of solar ultraviolet-B radiation (UV-B) have recently shown inhibition of the growth of some tropical forest tree seedlings. A knowledge of forest radiation environments is needed to help assess UV-B effects in natural situations. Although forest canopies strongly attenuate solar radiation, treefall gaps provide a very different radiation environment. We simultaneously measured both UV-B and photosynthetically active radiation (PAR) in forest gaps on Barro Colorado Island, Panama. Outside the forest, UV-B is predominately diffuse even under clear sky conditions. In sunflecks of small forest gaps, most of the UV-B was in the direct beam component. Compared to conditions outside the forest, the UV-B in these sunflecks was low relative to PAR. Shaded portions of the gap, in contrast, had proportionately high levels of UV-B relative to PAR. There are indications in the literature that relatively low UV-B levels may be effective under low PFD. Seasonal trends of PAR and UV-B in different locations in gaps can be inferred from hemispherical canopy photographs.

  13. The dependence on solar elevation of the correlation between monthly average hourly diffuse and global radiation

    SciTech Connect

    Soler, A. )

    1988-01-01

    In the present work, the dependence on {anti {gamma}} of the correlation between {anti K}{sub d} = {anti I}{sub d}/{anti I}{sub O} and {anti K}{sub t} = {anti I}/{anti I}{sub o} is studied, {anti I}, {anti I}{sub d}, and {anti I}{sub o} respectively being the monthly average hourly values of the global, diffuse, and extraterrestrial radiation, all of them on a horizontal surface, and {anti {gamma}} the solar elevation at midhour. The dependence is studied for Uccle for the following sky conditions. Condition A: clear skies (fraction of possible sunshine = 1) and the maximum values of direct radiation measured during the period considered (each of the hours before or after the solar noon for which radiation is received); Condition B corresponding to all the values of radiation measured when the sunshine fraction is 1 during the period considered; Condition C; corresponding to all the data collected, independently of the state of the sky; Condition D: corresponding to overcast skies ({anti I} = {anti I}{sub d}). From the available values of {anti I} and {anti I}{sub d} (monthly average hourly direct radiation on a horizontal surface), values of {anti K}{sub d} and {anti K}{sub t} for 5{degree} {le} {anti {gamma}} {le} 45{degree} and {Delta} {anti {gamma}} = 5{degree} are calculated using Newton's divided difference interpolation formula.

  14. Installation of a variable-angle spectrometer system for monitoring diffuse and global solar radiation

    NASA Astrophysics Data System (ADS)

    Ormachea, O.; Abrahamse, A.; Tolavi, N.; Romero, F.; Urquidi, O.; Pearce, J. M.; Andrews, R.

    2013-11-01

    We report on the design and installation of a spectrometer system for monitoring solar radiation in Cochabamba, Bolivia. Both the light intensity and the spectral distribution affect the power produced by a photovoltaic device. Local variations in the solar spectrum (especially compared to the AM1.5 standard) may have important implications for device optimization and energy yield estimation. The spectrometer system, based on an Ocean Optics USB4000 (300-900nm) spectrometer, was designed to increase functionality. Typically systems only record the global horizontal radiation. Our system moves a fiber-optic cable 0-90 degrees and takes measurements in 9 degree increments. Additionally, a shadow band allows measurement of the diffuse component of the radiation at each position. The electronic controls utilize an Arduino UNO microcontroller to synchronizes the movement of two PAP bipolar (stepper) motors with the activation of the spectrometer via an external trigger. The spectrometer was factory calibrated for wavelength and calibrated for absolute irradiance using a Sellarnet SL1-Cal light source. We present preliminary results from data taken March-June, 2013, and comment on implications for PV devices in Cochabamba.

  15. Solar radiation on Mars

    NASA Technical Reports Server (NTRS)

    Appelbaum, Joseph; Flood, Dennis J.

    1989-01-01

    Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. Presented here is a procedure and solar radiation related data from which the diurnally, hourly and daily variation of the global, direct beam and diffuse insolation on Mars are calculated. The radiation data are based on measured optical depth of the Martian atmosphere derived from images taken of the sun with a special diode on the Viking cameras; and computation based on multiple wavelength and multiple scattering of the solar radiation.

  16. Modeling the impacts of solar radiation partitioning into direct and diffuse fractions for the global water cycle

    NASA Astrophysics Data System (ADS)

    Oliveira, Paulo J. C.; Davin, Edouard L.; Seneviratne, Sonia I.

    2010-05-01

    Incident solar radiation at the Earth's surface affects plant photosynthesis and evapotranspiration, and consequently the global water budget. Observations from 1960-1990's across the Northern Hemisphere suggest that increased aerosol loadings from industrialization led not only to a decline in the intensity of solar radiation at the surface (global dimming), but also to a higher fraction of scattered light, which enhanced plant photosynthesis and the land carbon sink, with probable concurrent impacts on the water cycle. Thus, we used the NCAR Community Land Model (version 3.5) to perform global offline simulations and study the effects of the imposition of changes to radiation partitioning in diffuse and direct fractions on trends in evapotranspiration and runoff. We find that most modeled land surface variables respond to an increased-diffuse simulation where the relative fraction of radiation is changed globally at a high rate of increased diffuse as reported by some observation stations. Increased-diffuse partitioning causes a rise in total ET in all regions, an effect of opposite sign but smaller absolute value than that resulting from global dimming. Evapotranspiration rises by over 0.5 watt/m2 per decade in the tropics, due to increased shaded leaf stomatal conductance, with an opposite effect noted elsewhere due to lower ground evaporation. In the eastern U.S.A. and the Amazon basin, decadal trend anomalies in evapotranspiration for increased-diffuse radiation change reach 25-30% the absolute magnitude of those caused by dimming. Reductions to river runoff are modest nearly everywhere outside the Amazon. Understanding the mechanisms behind the interactions between solar radiation and the various land-surface components will help the development of climate models, improving predictions, in particular regarding changes in terrestrial hydrologic resources.

  17. Effects of the partitioning of diffuse and direct solar radiation on satellite-based modeling of crop gross primary production

    NASA Astrophysics Data System (ADS)

    Xin, Qinchuan; Gong, Peng; Suyker, Andrew E.; Si, Yali

    2016-08-01

    Modeling crop gross primary production (GPP) is critical to understanding the carbon dynamics of agro-ecosystems. Satellite-based studies have widely used production efficiency models (PEM) to estimate cropland GPP, wherein light use efficiency (LUE) is a key model parameter. One factor that has not been well considered in many PEMs is that canopy LUE could vary with illumination conditions. This study investigates how the partitioning of diffuse and direct solar radiation influences cropland GPP using both flux tower and satellite data. The field-measured hourly LUE under cloudy conditions was 1.50 and 1.70 times higher than that under near clear-sky conditions for irrigated corn and soybean, respectively. We applied a two-leaf model to simulate the canopy radiative transfer process, where modeled photosynthetically active radiation (PAR) absorbed by canopy agreed with tower measurements (R2 = 0.959 and 0.914 for corn and soybean, respectively). Derived canopy LUE became similar after accounting for the impact of light saturation on leaf photosynthetic capacity under varied illumination conditions. The impacts of solar radiation partitioning on satellite-based modeling of crop GPP was examined using vegetation indices (VI) derived from MODIS data. Consistent with the field modeling results, the relationship between daily GPP and PAR × VI under varied illumination conditions showed different patterns in terms of regression slope and intercept. We proposed a function to correct the influences of direct and diffuse radiation partitioning and the explained variance of flux tower GPP increased in all experiments. Our results suggest that the non-linear response of leaf photosynthesis to light absorption contributes to higher canopy LUE on cloudy days than on clear days. We conclude that accounting for the impacts of solar radiation partitioning is necessary for modeling crop GPP on a daily or shorter basis.

  18. Spectroscopy of diffuse light in dust clouds. Scattered light and the solar neighbourhood radiation field

    NASA Astrophysics Data System (ADS)

    Lehtinen, K.; Mattila, K.

    2013-01-01

    Context. The optical surface brightness of dark nebulae is mainly due to scattering of integrated starlight by classical dust grains. It contains information on the impinging interstellar radiation field, cloud structure, and grain scattering properties. We have obtained spectra of the scattered light from 3500 to 9000 Å in two globules, the Thumbprint Nebula and DC 303.8-14.2. Aims. We use observations of the scattered light to study the impinging integrated starlight spectrum as well as the scattered Hα and other line emissions from all over the sky. We search also for the presence of other than scattered light in the two globules. Methods. We obtained long-slit spectra encompassing the whole globule plus adjacent sky in a one-slit setting, thus enabling efficient elimination of airglow and other foreground sky components. We calculated synthetic integrated starlight spectra for the solar neighbourhood using HIPPARCOS-based stellar distributions and the spectral library of Pickles. Results. Spectra are presented separately for the bright rims and dark cores of the globules. The continuum spectral energy distributions and absorption line spectra can be well modelled with the synthetic integrated starlight spectra. Emission lines of Hα +[N II], Hβ, and [S II] are detected and are interpreted in terms of scattered light plus an in situ warm ionized medium component behind the globules. We detected an excess of emission over the wavelength range 5200-8000 Å in DC 303.8-14.2 but the nature of this emission remains open. Based on observations collected at the European Southern Observatory, Chile, under programme ESO No. 073.C-0239(A). Appendix A is available in electronic form at http://www.aanda.org.

  19. Diffuse UV Background Radiation

    NASA Astrophysics Data System (ADS)

    Conn Henry, Richard; Murthy, J.

    2012-01-01

    The diffuse UV sky is expected to glow with significant amounts of starlight that is scattered from the interstellar dust. The albedo and scattering pattern of the dust in the ultraviolet are both well established, and are both fairly independent of wavelength from 912 Å to 3000 Å. We present 1943 Voyager spectra of the diffuse cosmic background radiation from 500 Å to 1200 Å, and we compare their brightnesses, and their distribution on the sky, to those observed (Murthy et al., ApJ 724, 1389, 2010) from the GALEX mission at longer wavelengths (1530 Å). Significant differences appear, suggesting that background radiation components in addition to dust-scattered starlight may be present in both spectral regions.

  20. Solar Radiation Empirical Quality Assessment

    1994-03-01

    The SERIQC1 subroutine performs quality assessment of one, two, or three-component solar radiation data (global horizontal, direct normal, and diffuse horizontal) obtained from one-minute to one-hour integrations. Included in the package is the QCFIT tool to derive expected values from historical data, and the SERIQC1 subroutine to assess the quality of measurement data.

  1. Solar radiation on inclined surfaces

    NASA Astrophysics Data System (ADS)

    1980-05-01

    Mean monthly values of daily shortwave radiation on inclined surfaces are presented for 13 locations in India. Values of direct, diffuse sky, reflected, and total shortwave radiation incident on an inclined surface are given for 9 slope angles (measured from the horizontal) and 8 aspects. All the data are computed using measured values of the total shortwave radiation on a horizontal surface according to the techniques described. Maximum and minimum values of direct solar radiation during each month are underlined and marked by asterisk respectively. Actual and potential users of radiation data, particularly those in the fields of agriculture, horticulture, forestry, architecture, heating and ventilating engineering, and photovoltaic systems, it is hoped, would find this publication useful in planning and designing of solar radiation devices.

  2. [Solar cosmic radiation and the radiation hazard of space flight].

    PubMed

    Miroshnichenko, L I

    1983-01-01

    Present-day data on the spectrum of solar radiation in the source and near the Earth are discussed as applied to the radiation safety of crewmembers and electronics onboard manned and unmanned spacecraft. It is shown that the slope of the solar radiation spectrum changes (flattens) in the low energy range. Quantitative information about absolute solar radiation fluxes near the Earth is summarized in relation to the most significant flares of 1956--1978. The time-related evolution of the solar radiation spectrum in the interplanetary space is described in quantitative terms (as illustrated by the solar flare of 28 September 1961). It is indicated that the nonmonotonic energy dependence of the transport path of solar radiation in the interplanetary space should be taken into consideration. It is demonstrated that the diffusion model of propagation can be verified using solar radiation measurements in space flights.

  3. Diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1977-01-01

    An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

  4. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Carter, J. R., Jr.; Tada, H. Y.

    1973-01-01

    A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

  5. Solar radiation on Mars: Stationary photovoltaic array

    NASA Technical Reports Server (NTRS)

    Appelbaum, J.; Sherman, I.; Landis, G. A.

    1993-01-01

    Solar energy is likely to be an important power source for surface-based operation on Mars. Photovoltaic cells offer many advantages. In this article we have presented analytical expressions and solar radiation data for stationary flat surfaces (horizontal and inclined) as a function of latitude, season and atmospheric dust load (optical depth). The diffuse component of the solar radiation on Mars can be significant, thus greatly affecting the optimal inclination angle of the photovoltaic surface.

  6. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.

    1977-01-01

    Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

  7. Solar radiation on Mars: Update 1991

    NASA Technical Reports Server (NTRS)

    Appelbaum, Joseph; Landis, Geoffrey A.

    1991-01-01

    Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned solar energy systems operating on the surface of Mars. A procedure and solar radiation related data are presented from which the daily variation of the global, direct beam and diffuse insolation on Mars are calculated. Given the optical depth of the Mars atmosphere, the global radiation is calculated from the normalized net flux function based on multiple wavelength and multiple scattering of the solar radiation. The direct beam was derived from the optical depth using Beer's law, and the diffuse component was obtained from the difference of the global and the direct beam radiation. The optical depths of the Mars atmosphere were derived from images taken of the Sun with a special diode on the cameras used on the two Viking Landers.

  8. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  9. Measurement of solar radiation

    SciTech Connect

    Braunstein, A.; Levite, T.; Sohar, E.

    1984-11-27

    There is provided a device for indicating the level of solar radiation intensity, and especially that region of the spectrum in the ultraviolet region which causes sunburn. The device may be provided with an output subdivided into a plurality of discrete levels of intensity indicated as numerals and figures. It may be provided with means of adjustment to the physiology of the user.

  10. Characterizations of the mirror attenuator mosaic - Solar diffuser plate

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Avis, Lee M.; Gibson, M. A.; Kopia, Leonard P.

    1992-01-01

    The mirror attenuator mosaic (MAM), a solar diffuser plate, was used for the flight calibration of the broadband shortwave (0.2-5-microns) and total (0.2 to greater than 200-microns) Earth Radiation Budget Experiment scanning thermistor bolometer radiometers. The MAM solar-reflecting surface consisted of a tightly packed array of vacuum-deposited aluminum, concave spherical mirrors, while its solar-absorbing surface consisted of black chrome. The effective reflectance of the MAM was constant to within +/- 2 percent after almost 2 years in orbit, a marked improvement over earlier solar diffusers.

  11. Automatic actinometric system for diffuse radiation measurement

    NASA Astrophysics Data System (ADS)

    Litwiniuk, Agnieszka; Zajkowski, Maciej

    2015-09-01

    Actinometric station is using for measuring solar of radiation. The results are helpful in determining the optimal position of solar panels relative to the Sun, especially in today's world, when the energy coming from the Sun and other alternative sources of energy become more and more popular. Polish climate does not provide as much energy as in countries in southern Europe, but it is possible to increase the amount of energy produced by appropriate arrangement of photovoltaic panels. There is the possibility of forecasting the amount of produced energy, the cost-effectiveness and profitability of photovoltaic installations. This implies considerable development opportunities for domestic photovoltaic power plants. This article presents description of actinometric system for diffuse radiation measurement, which is equipped with pyranometer - thermopile temperature sensor, amplifier AD620, AD Converter ADS1110, microcontroller Atmega 16, SD card, GPS module and LCD screen.

  12. The diffuse component of erythemal ultraviolet radiation.

    PubMed

    Silva, Abel A

    2015-11-01

    The diffuse (Dif) component of ultraviolet radiation (UVR) plays an important role in the daily exposure of humans to solar radiation. This study proposes a semi-empirical method to obtain the Dif component of the erythemal dose rate, or the erythemally weighted irradiance, (EDRDif) calculated from synchronized measurements of the Dif component of UVR (UVDif) and the global (G) irradiances of both UVR (UVG) and the erythemal dose rate (EDRG). Since the study was conducted in the tropics, results involve a wide range of solar zenith angles to which EDRDif is seasonally dependent. Clouds are the main atmospheric agent affecting Dif radiation. The ratio between Dif and G (Dif/G) showed a quadratic dependence on cloud cover with a coefficient of determination r(2) = 0.79. The maxima of EDRDif were mainly above the moderate range (>137.5 mW m(-2)) of the UV-Index and reached the extreme range (>262.5 mW m(-2)) for the spring-summer period. The fraction of the global daily erythemal dose (daily EDG) corresponding to Dif radiation (daily EDDif) ranged from 936 J m(-2) to 5053 J m(-2) and averaged 2673 J m(-2). Daily EDDif corresponded to at least 48% of daily EDG for a practically cloudless sky. Therefore, Dif radiation is a real threat. Lighter skin people (types I and II) can get sunburnt in a couple of minutes under such an incidence of radiation. Moreover, accumulative harm can affect all skin types.

  13. Diffuse Cosmic Infrared Background Radiation

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2002-01-01

    The diffuse cosmic infrared background (CIB) consists of the cumulative radiant energy released in the processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In this lecture I will review the observational data that provided the first detections and limits on the CIB, and the theoretical studies explaining the origin of this background. Finally, I will also discuss the relevance of this background to the universe as seen in high energy gamma-rays.

  14. Simple device measures solar radiation

    NASA Technical Reports Server (NTRS)

    Humphries, W. R.

    1977-01-01

    Simple inexpensive thermometer, insolated from surroundings by transparent glass or plastic encasement, measures intensities of solar radiation, or radiation from other sources such as furnaces or ovens. Unit can be further modified to accomplish readings from remote locations.

  15. Diffusion length and solar cell efficiency

    NASA Astrophysics Data System (ADS)

    Huber, D.; Wahlich, R.; Bachmaier, A.

    The diffusion length of the minority carriers of a solar cell defines the appropriate technology which should be applied for the solar cell fabrication. Back surface techniques only pay off if the diffusion length is long enough. Monocrystalline material with different lifetime killing defects was investigated and an experimental correlation between the diffusion length measured on the unprocessed wafer and the efficiency of the finished cell could be established.

  16. Local effects of partly cloudy skies on solar and emitted radiations

    NASA Technical Reports Server (NTRS)

    Whitney, D. A.; Venable, D. D.

    1981-01-01

    Solar radiation measurements are made on a routine basis. Global solar, atmospheric emitted, downwelled diffuse solar, and direct solar radiation measurement systems are fully operational with the first two in continuous operation. Fractional cloud cover measurements are made from GOES imagery or from ground based whole sky photographs. Normalized global solar irradiance values for partly cloudy skies were correlated to fractional cloud cover.

  17. Dependence on solar elevation and the daily sunshine fraction of the correlation between monthly-average-hourly diffuse and global radiation

    SciTech Connect

    Soler, A. )

    1992-01-01

    In the present work the authors study for Uccle, Belgium data (50{degree}48 minutes N, 4{degree}21 minutes E), the dependence on {anti {gamma}} and {sigma} of the correlations between {anti K}{sub d} = {anti I}{sub d}/{anti I}{sub o} and {anti I}{sub t} = {anti I}/{anti I}{sub o}, where {anti I}, {anti I}{sub d}, and {anti I}{sub o} are respectively, the monthly-average-hourly value of global, diffuse, and extraterrestrial radiation (all of them on a horizontal surface), {anti {gamma}} is the solar elevation at midhour and {sigma} the daily sunshine fraction. The dependence on {sigma} is studied for different ranges of values, from {sigma} = 0 to {sigma} > 0.9. The dependence on {anti {gamma}} is studied for {anti {gamma}} = 5{degree}, 10{degree}, 15{degree}, 25{degree}-30{degree}; 35{degree}-40{degree}; 45{degree}-60{degree} ({delta}{anti {gamma}} = 5{degree}). Relating the dependence on {sigma}, for increasing values of {sigma}({sigma} {>=} 0), there is an increase in {anti K}{sub d} with the increase in {anti K}{sub t}. For 0.42 < {anti K}{sub t} < 0.52 a maximum is obtained for {anti K}{sub d}. After the maximum, as the skies become clearer, {anti K}{sub d} decreases as {anti K}{sub t} increases. Relating the dependence on {anti {gamma}}, for each range of values of {sigma} ({sigma} > 0.2), values of the slope for linear {anti K}{sub d} = f({anti K}{sub t}) correlations show a tendency to decrease as {anti {gamma}} increases. For each value of {anti {gamma}} the slopes of the linear {anti K}{sub d} = f({anti K}{sub t}) correlations tend to decrease when {sigma} increases.

  18. Solar Radiation Modeling and Measurements for Renewable Energy Applications: Data and Model Quality; Preprint

    SciTech Connect

    Myers, D. R.

    2003-03-01

    Measurement and modeling of broadband and spectral terrestrial solar radiation is important for the evaluation and deployment of solar renewable energy systems. We discuss recent developments in the calibration of broadband solar radiometric instrumentation and improving broadband solar radiation measurement accuracy. An improved diffuse sky reference and radiometer calibration and characterization software and for outdoor pyranometer calibrations is outlined. Several broadband solar radiation model approaches, including some developed at the National Renewable Energy Laboratory, for estimating direct beam, total hemispherical and diffuse sky radiation are briefly reviewed. The latter include the Bird clear sky model for global, direct beam, and diffuse terrestrial solar radiation; the Direct Insolation Simulation Code (DISC) for estimating direct beam radiation from global measurements; and the METSTAT (Meteorological and Statistical) and Climatological Solar Radiation (CSR) models that estimate solar radiation from meteorological data. We conclude that currently the best model uncertainties are representative of the uncertainty in measured data.

  19. MODIS Solar Diffuser: Modelled and Actual Performance

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xiong, Xiao-Xiong; Esposito, Joe; Wang, Xin-Dong; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument's solar diffuser is used in its radiometric calibration for the reflective solar bands (VIS, NTR, and SWIR) ranging from 0.41 to 2.1 micron. The sun illuminates the solar diffuser either directly or through a attenuation screen. The attenuation screen consists of a regular array of pin holes. The attenuated illumination pattern on the solar diffuser is not uniform, but consists of a multitude of pin-hole images of the sun. This non-uniform illumination produces small, but noticeable radiometric effects. A description of the computer model used to simulate the effects of the attenuation screen is given and the predictions of the model are compared with actual, on-orbit, calibration measurements.

  20. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    SciTech Connect

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  1. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  2. Measurements of the diffuse ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Fix, John D.; Craven, John D.; Frank, Louis A.

    1989-01-01

    The imaging instrumentation on the Dynamics Explorer 1 satellite has been used to measure the intensity of the diffuse ultraviolet radiation on two great circles about the sky. It is found that the isotropic component of the diffuse ultraviolet radiation (possibly of extragalactic origin) has an intensity of 530 + or - 80 units (a unit is 1 photon per sq cm s A sr) at a wavelength of 150 nm. The Galactic component of the diffuse ultraviolet radiation has a dependence on Galactic latitude which requires strongly forward scattering particles if it is produced by dust above the Galactic plane.

  3. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    History of GaAs solar cell development is provided. Photovoltaic equations are described along with instrumentation techniques for measuring solar cells. Radiation effects in solar cells, electrical performance, and spacecraft flight data for solar cells are discussed. The space radiation environment and solar array degradation calculations are addressed.

  4. Diffusion processes in general relativistic radiating spheres

    SciTech Connect

    Barreto, W.; Herrera, L.; Santos, N.O.; Universidad Central de Venezuela, Caracas; Observatorio Nacional do Brasil, Rio de Janeiro )

    1989-09-01

    The influence of diffusion processes on the dynamics of general relativistic radiating spheres is systematically studied by means of two examples. Differences between the streaming-out limit and the diffusion limit are exhibited, for both models, through the evolution curves of dynamical variables. In particular it is shown the Bondi mass decreases, for both models, in the diffusion limit as compared with its value at the streaming-out regime. 15 refs.

  5. Analytic expressions for ULF wave radiation belt radial diffusion coefficients

    PubMed Central

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-01-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440

  6. Ground truth data for test sites (SL-4). [thermal radiation brightness temperature and solar radiation measurments

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Field measurements performed simultaneous with Skylab overpass in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. Wavelength region covered include: solar radiation (400 to 1300 nanometer), and thermal radiation (8 to 14 micrometer). Measurements consisted of general conditions and near surface meteorology, atmospheric temperature and humidity vs altitude, the thermal brightness temperature, total and diffuse solar radiation, direct solar radiation (subsequently analyzed for optical depth/transmittance), and target reflectivity/radiance. The particular instruments used are discussed along with analyses performed. Detailed instrument operation, calibrations, techniques, and errors are given.

  7. Separating the effects of phenology and diffuse radiation on gross primary productivity in winter wheat

    NASA Astrophysics Data System (ADS)

    Williams, Ian N.; Riley, William J.; Kueppers, Lara M.; Biraud, Sebastien C.; Torn, Margaret S.

    2016-07-01

    Gross primary productivity (GPP) has been reported to increase with the fraction of diffuse solar radiation, for a given total irradiance. The correlation between GPP and diffuse radiation suggests effects of diffuse radiation on canopy light-use efficiency, but potentially confounding effects of vegetation phenology have not been fully explored. We applied several approaches to control for phenology, using 8 years of eddy-covariance measurements of winter wheat in the U.S. Southern Great Plains. The apparent enhancement of daily GPP due to diffuse radiation was reduced from 260% to 75%, after subsampling over the peak growing season or by subtracting a 15 day moving average of GPP, suggesting a role of phenology. The diffuse radiation effect was further reduced to 22% after normalizing GPP by a spectral reflectance index to account for phenological variations in leaf area index LAI and canopy photosynthetic capacity. Canopy photosynthetic capacity covaries with diffuse fraction at a given solar irradiance at this site because both factors are dependent on day of year or solar zenith angle. Using a two-leaf Sun-shaded canopy radiative transfer model, we confirmed that the effects of phenological variations in photosynthetic capacity can appear qualitatively similar to the effects of diffuse radiation on GPP and therefore can be difficult to distinguish using observations. The importance of controlling for phenology when inferring diffuse radiation effects on GPP raises new challenges and opportunities for using radiation measurements to improve carbon cycle models.

  8. Methods to Estimate Solar Radiation Dosimetry in Coral Reefs Using Remote Sensed, Modeled, and in Situ Data.

    EPA Science Inventory

    Solar irradiance has been increasingly recognized as an important determinant of bleaching in coral reefs, but measurements of solar radiation exposure within coral reefs have been relatively limited. Solar irradiance and diffuse down welling attenuation coefficients (Kd, m-1) we...

  9. Solar radiation and cutaneous melanoma.

    PubMed

    Viola, M V; Houghton, A N

    1982-09-01

    Exposure to solar radiation has been widely implicated in the dramatic rise in the incidence of cutaneous melanoma throughout the world. The association may be more complex than originally suspected, involving such factors as sunspot-activity cycles and changes in the ozone layer affecting ultraviolet flux at the earth's surface. The evidence for these relationships is examined.

  10. SORCE: Solar Radiation and Climate Experiment

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert; Rottman, Gary; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Contents include the following: Understanding the Sun's influence on the Earth; How the Sun affect Earth's climate; By how much does the Sun's radiation very; Understanding Solar irradiance; History of Solar irradiance observations; The SORCE mission; How do the SORCE instruments measure solar radiation; Total irradiance monitor (TIM); Spectral irradiance monitor (SIM); Solar stellar irradiance comparison experiment (SOLSTICE); XUV photometer system (XPS).

  11. Early solar mass loss, element diffusion, and solar oscillation frequencies

    SciTech Connect

    Guzik, J.A.; Cox, A.N.

    1994-07-01

    Swenson and Faulkner, and Boothroyd et al. investigated the possibility that early main-sequence mass loss via a stronger early solar wind could be responsible for the observed solar lithium and beryllium depiction. This depletion requires a total mass loss of {approximately}0.1 M{circle_dot}, nearly independent of the mass loss timescale. We have calculated the evolution and oscillation frequencies of solar models including helium and element diffusion, and such early solar mass loss. We show that extreme mass loss of 1 M{circle_dot} is easily ruled out by the low-degree p-modes that probe the solar center and sense the steeper molecular weight gradient produced by the early phase of more rapid hydrogen burning. The effects on central structure are much smaller for models with an initial mass of 1.1 M{circle_dot} and exponentially-decreasing mass loss irate with e-folding timescale 0.45 Gyr. While such mass loss slightly worsens the agreement between observed and calculated low-degree modes, the observational uncertainties of several tenths of a microhertz weaken this conclusion. Surprisingly, the intermediate-degree modes with much smaller observational uncertainties that probe the convection zone bottom prove to be the key to discriminating between models: The early mass loss phase decreases the total amount of helium and heavier elements diffused from the convection zone, and the extent of the diffusion produced composition gradient just below the convection zone, deteriorating the agreement with observed frequencies for these modes. Thus it appears that oscillations can also rule out this smaller amount of gradual early main-sequence mass loss in the young Sun. The mass loss phase must be confined to substantially under a billion years, probably 0.5 Gyr or less, to simultaneously solve the solar Li/Be problem and avoid discrepancies with solar oscillation frequencies.

  12. Commission 12: Solar Radiation & Structure

    NASA Astrophysics Data System (ADS)

    Bogdan, Thomas. J.; Martínez Pillet, Valentin; Asplund, M.; Christensen-Dalsgaard, J.; Cauzzi, G.; Cram, L. E.; Dravins, D.; Gan, W.; Henzl, P.; Kosovichev, A.; Mariska, J. T.; Rovira, M. G.; Venkatakrishnan, P.

    2007-03-01

    Commission 12 covers research on the internal structure and dynamics of the Sun, the "quiet" solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. There is considerable productive overlap with the other Commissions of Division II as investigations move progressively toward the fertile intellectual boundaries between traditional research disciplines. In large part, the solar magnetic field provides the linkage that connects these diverse themes. The same magnetic field that produces the more subtle variations of solar structure and radiative output over the 11 yr activity cycle is also implicated in rapid and often violent phenomena such as flares, coronal mass ejections, prominence eruptions, and episodes of sporadic magnetic reconnection.The last three years have again brought significant progress in nearly all the research endeavors touched upon by the interests of Commission 12. The underlying causes for this success remain the same: sustained advances in computing capabilities coupled with diverse observations with increasing levels of spatial, temporal and spectral resolution. It is all but impossible to deal with these many advances here in anything except a cursory and selective fashion. Thankfully, the Living Reviews in Solar Physics; has published several extensive reviews over the last two years that deal explicitly with issues relevant to the purview of Commission 12. The reader who is eager for a deeper and more complete understanding of some of these advances is directed to http://www.livingreviews.org for access to these articles.

  13. Estimating solar radiation for plant simulation models

    SciTech Connect

    Hodges, T.; French, V.; Leduc, S.

    1985-01-01

    Five algorithms producing daily solar radiation surrogates using daily temperatures and rainfall were evaluated using measured solar radiation data for seven U.S. locations. The algorithms were compared both in terms of accuracy of daily solar radiation estimates and terms of response when used in a plant growth simulation model (CERES-wheat). Requirements for accuracy of solar radiation for plant growth simulation models are discussed. One algorithm is recommended as being best suited for use in these models when neither measured nor satellite estimated solar radiation values are available.

  14. Cloud Induced Enhancement of Ground Level Solar Radiation

    NASA Astrophysics Data System (ADS)

    Inman, R.; Chu, Y.; Coimbra, C.

    2013-12-01

    Atmospheric aerosol and cloud cover are typically associated with long and short-term variability of all three solar radiation components at the ground level. Although aerosol attenuation can be a substantial factor for Direct Normal Irradiance (DNI) in some microclimates, the strongest factor for ground level irradiance attenuation is cloud cover which acts on time-scales associated with strong solar power generation fluctuations. Furthermore, the driving effects of clouds on radiative energy budgets include shortwave cooling, as a result of absorption of incoming solar radiation, and longwave heating, due to reduced emission of thermal radiation by relatively cool cloud tops. Under special circumstances, the presence of clouds in the circumsolar region may lead to the reverse; a local increase in the diffuse downwelling solar radiation due to directional scattering from clouds. This solar beam effect exceed the losses resulting from the backscattering of radiation into space. Such conditions result in radiation levels that temporarily exceed the localized clear sky values. These phenomena are referred to as Cloud Enhancement Events (CEEs). There are currently two fundamental CEE mechanisms discussed in the literature. The first involves well-defined, and optically thick cloud edges close to, but not obscuring, the solar disk. The effect here is of producing little or no change in the normal beam radiation. In this case, cloud edges in the vicinity of the sun create a non-isotropic increase in the local diffuse radiation field with respect to the isotropic scattering of a clear-sky atmosphere. The second type of CEE allows for partial or full obstruction of the solar disk by an optically thin diffuser such as fine clouds, haze or fog; which results in an enhanced but still nearly isotropic diffuse radiation field. In this study, an entire year of solar radiation data and total sky images taken at 30 second resolution at the University of California, Merced (UCM

  15. Comparative performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.; Parat, K. K.

    1987-01-01

    A comparison is made between indium phosphide solar cells whose p-n junctions were processed by open tube capped diffusion, and closed tube uncapped diffusion, of sulfur into Czochralski grown p-type substrates. Air mass zero, total area, efficiencies ranged from 10 to 14.2 percent, the latter value attributed to cells processed by capped diffusion. The radiation resistance of these latter cells was slightly better, under 1 MeV electron irradiation. However, rather than being process dependent, the difference in radiation resistance could be attributed to the effects of increased base dopant concentration. In agreement with previous results, both cells exhibited radiation resistance superior to that of gallium arsenide. The lowest temperature dependency of maximum power was exhibited by the cells prepared by open tube capped diffusion. Contrary to previous results, no correlation was found between open circuit voltage and the temperature dependency of Pmax. It was concluded that additional process optimization was necessary before concluding that one process was better than another.

  16. NREL Solar Radiation Resource Assessment Project: Status and outlook

    SciTech Connect

    Renne, D.; Riordan, C.; Maxwell, E.; Stoffel, T.; Marion, B.; Rymes, M.; Wilcox, S.; Myers, D.

    1992-05-01

    This report summarizes the activities and accomplishments of NREL's Solar Radiation Resource Assessment Project during fiscal year 1991. Currently, the primary focus of the SRRAP is to produce a 1961--1990 National Solar Radiation Data Base, providing hourly values of global horizontal, diffuse, and direct normal solar radiation at approximately 250 sites around the United States. Because these solar radiation quantities have been measured intermittently at only about 50 of these sites, models were developed and applied to the majority of the stations to provide estimates of these parameters. Although approximately 93% of the data base consists of modeled data this represents a significant improvement over the SOLMET/ERSATZ 1952--1975 data base. The magnitude and importance of this activity are such that the majority of SRRAP human and financial in many other activities, which are reported here. These include the continued maintenance of a solar radiation monitoring network in the southeast United States at six Historically Black Colleges and Universities (HBCU's), the transfer of solar radiation resource assessment technology through a variety of activities, participation in international programs, and the maintenance and operation of NREL's Solar Radiation Research Laboratory. 17 refs.

  17. Diffuse ionizing radiation within HH jets

    SciTech Connect

    Esquivel, A.; Raga, A. C. E-mail: raga@nucleares.unam.mx

    2013-12-20

    We present numerical hydrodynamical simulations of a time-dependent ejection velocity precessing jet. The parameters used in our models correspond to a high excitation Herbig-Haro object, such as HH 80/81. We have included the transfer of ionizing radiation produced within the shocked regions of the jet. The radiative transfer is computed with a ray-tracing scheme from all the cells with an emissivity above a certain threshold. We show the development of a radiative precursor, and compare the morphology with a model without the diffuse radiation. Our simulations show that the morphology of the Hα emission is affected considerably if the diffuse ionizing radiation is accounted for. The predicted Hα position-velocity diagram (i.e., spatially resolved emission line profiles) from a model with the transfer of ionizing radiation has a relatively strong component at zero velocity, corresponding to the radiative precursor. Qualitatively similar 'zero velocity components' are observed in HH 80/81 and in the jet from Sanduleak's star in the Large Magellanic Cloud.

  18. 1961-1990 Solar Radiation Data Base

    SciTech Connect

    Not Available

    1990-01-01

    A new 1961-1990 Solar Radiation Data Base for the United States is being compiled at the Solar Energy Research Institute. Using solar radiation and climate data collected by the National Weather Service (NWS) from 1977 to 1990 and improved computer models to fill in missing data, this update will significantly upgrade the current national SOLMET/ERSATZ data base.

  19. Fires increase Amazon forest productivity through increases in diffuse radiation

    NASA Astrophysics Data System (ADS)

    Rap, A.; Spracklen, D. V.; Mercado, L.; Reddington, C. L.; Haywood, J. M.; Ellis, R. J.; Phillips, O. L.; Artaxo, P.; Bonal, D.; Restrepo Coupe, N.; Butt, N.

    2015-06-01

    Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8% and net primary production (NPP) by 1.4-2.8%, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156 Tg C a-1 is equivalent to 33-65% of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60 Tg C a-1 of this NPP enhancement is within woody tissue, accounting for 8-16% of the observed carbon sink across mature Amazonian forests.

  20. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    The handbook discusses the history of GaAs solar cell development, presents equations useful for working with GaAs solar cells, describes commonly used instrumentation techniques for assessing radiation effects in solar cells and fundamental processes occurring in solar cells exposed to ionizing radiation, and explains why radiation decreases the electrical performance of solar cells. Three basic elements required to perform solar array degradation calculations: degradation data for GaAs solar cells after irradiation with 1 MeV electrons at normal incidence; relative damage coefficients for omnidirectional electron and proton exposure; and the definition of the space radiation environment for the orbit of interest, are developed and used to perform a solar array degradation calculation.

  1. Radiation hydrodynamics in solar flares

    SciTech Connect

    Fisher, G.H.

    1985-10-18

    Solar flares are rather violent and extremely complicated phenomena, and it should be made clear at the outset that a physically complete picture describing all aspects of flares does not exist. From the wealth of data which is available, it is apparent that many different types of physical processes are involved during flares: energetic particle acceleration, rapid magnetohydrodynamic motion of complex field structures, magnetic reconnection, violent mass motion along magnetic field lines, and the heating of plasma to tens of millions of degrees, to name a few. The goal of this paper is to explore just one aspect of solar flares, namely, the interaction of hydrodynamics and radiation processes in fluid being rapidly heated along closed magnetic field lines. The models discussed are therefore necessarily restrictive, and will address only a few of the observed or observable phenomena. 46 refs., 6 figs.

  2. Historically Black Colleges and Universities (HBCU) Solar Radiation Monitoring Network

    DOE Data Explorer

    The Historically Black Colleges and Universities (HBCU) Solar Radiation Monitoring Network operated from November 1985 through December 1996. The six-station network provided 5-minute averaged measurements of global and diffuse horizontal solar irradiance. The data were processed at the National Renewable Energy Laboratory (NREL) to improve the assessment of the solar radiation resources in the southeastern United States. Three of the stations also measured the direct-normal solar irradiance with a pyrheliometer mounted in an automatic sun tracker. All data are archived in the Standard Broadband Format (SBF) with quality-assessment indicators. Monthly data summaries and plots are also available for each month. In January 1997 the HBCU sites became part of the CONFRRM solar monitoring network.

  3. Solar Atmospheric Magnetic Energy Coupling: Radiative Redistribution Efficiency

    NASA Astrophysics Data System (ADS)

    Orange, N. Brice; Gendre, Bruce; Morris, David C.; Chesny, David

    2016-07-01

    Essential to many outstanding solar and stellar physics problems is elucidating the dynamic magnetic to radiative energy coupling of their atmospheres. Using three years of Solar Dynamics Observatory's Atmospheric Imaging Assembly and Heliosemic Magnetic Imager data of gross atmospheric feature classes, an investigation of magnetic and radiative energy redistribution is detailed. Self-consistent radiative to temperature distributions, that include magnetic weighting, of each feature class is revealed via utilizing the upper limit of thermodynamic atmospheric conditions provided by Active Region Cores (ARCs). Distinctly interesting is that our radiative energy distributions, though indicative to a linearly coupling with temperature, highlight the manifestation of diffuse ``unorganized" emission at upper transition region -- lower coronal regimes. Results we emphasize as correlating remarkably with emerging evidence for similar dependencies of magnetic energy redistribution efficiency with temperature, i.e., linearly with an embedded diffuse emitting region. We present evidence that our magnetic and radiative energy coupling descriptions are consistent with established universal scaling laws for large solar atmospheric temperature gradients and descriptions to the unresolved emission, as well as their insight to a potential origin of large variability in their previous reports. Finally, our work casts new light on the utility of narrowband observations as ad hoc tools for detailing solar atmospheric thermodynamic profiles, thus, presenting significant provisions to the field of solar and stellar physics, i.e., nature of coronae heating.

  4. Solar Radiation Data from the World Radiation Data Centre (WRDC) Online Archive

    DOE Data Explorer

    The WRDC, located at the Main Geophysical Observatory in St. Petersburg, Russia, serves as a central depository for solar radiation data collected at over 1000 measurement sites throughout the world. The WRDC was established in accordance with Resolution 31 of WMO Executive Committee XVIII in 1964. The WRDC centrally collects, archives and published radiometric data from the world to ensure the availability of these data for research by the international scientific community. The WRDC archive contains the following measurements (not all observations are made at all sites): • Global solar radiationDiffuse solar radiation • Downward atmospheric radiation • Sunshine duration • Direct solar radiation (hourly and instantaneous) • Net total radiation • Net terrestrial surface radiation (upward) • Terrestrial surface radiation • Reflected solar radiation • Spectral radiation components (instantaneous fluxes) At present, this online archive contains a subset of the data stored at the WRDC. As new measurements are received and processed, they are added to the archive. The archive currently contains all available data from 1964-1993.[From ôBackground on the WRDCö at http://wrdc-mgo.nrel.gov/html/about.html

  5. Variability of Solar Radiation under Cloud-Free Skies in China: The Role of Aerosols

    NASA Technical Reports Server (NTRS)

    Qian, Yun; Wang, Weiguo; Leung, L. ruby; Kaiser, Dale P.

    2007-01-01

    In this study, we analyzed long-term surface global and diffuse solar radiation, aerosol single scattering albedo (SSA), and relative humidity (RH) from China. Our analysis reveals that much of China experienced significant decreases in global solar radiation (GSR) and increases in diffuse solar radiation under cloud-free skies between the 1960s and 1980s. With RH and aerosol SSA being rather constant during that time period, we suggest that the increasing aerosol loading from emission of pollutants is responsible for the observed reduced GSR and increased diffuse radiation in cloud-free skies. Although pollutant emissions continue to increase after the 1980s, the increment of aerosol SSA since 1980s can partly explain the transition of GSR from a decreasing trend to no apparent trend around that time. Preliminary analysis is also provided on the potential role of RH in affecting the global and diffuse solar radiation reaching the earth surface.

  6. Diffusion models for Jupiter's radiation belt

    NASA Technical Reports Server (NTRS)

    Jacques, S. A.; Davis, L., Jr.

    1972-01-01

    Solutions are given for the diffusion of trapped particles in a planetary magnetic field in which the first and second adiabatic invariants are preserved but the third is not, using as boundary conditions a fixed density at the outer boundary (the magnetopause) and a zero density at an inner boundary (the planetary surface). Losses to an orbiting natural satellite are included and an approximate evaluation is made of the effects of the synchrotron radiation on the energy of relativistic electrons. Choosing parameters appropriate to Jupiter, the electrons required to produce the observed synchrotron radiation are explained. If a speculative mechanism in which the diffusion is driven by ionospheric wind is the true explanation of the electrons producing the synchrotron emission it can be concluded that Jupiter's inner magnetosphere is occupied by an energetic proton flux that would be a serious hazard to spacecraft.

  7. Solar radiation and human health

    NASA Astrophysics Data System (ADS)

    Juzeniene, Asta; Brekke, Pål; Dahlback, Arne; Andersson-Engels, Stefan; Reichrath, Jörg; Moan, Kristin; Holick, Michael F.; Grant, William B.; Moan, Johan

    2011-06-01

    The Sun has played a major role in the development of life on Earth. In Western culture, people are warned against Sun exposure because of its adverse effects: erythema, photoimmunosuppression, photoageing, photocarcinogenesis, cataracts and photokeratitis. However, Sun exposure is also beneficial, since moderate doses give beneficial physiological effects: vitamin D synthesis, reduction of blood pressure and mental health. Shortage of Sun exposure may be even more dangerous to human health than excessive exposure. Avoiding Sun exposure leads to vitamin D deficiency which is associated not only with rickets and osteomalacia, but also with increased risk of cardiovascular disease, multiple sclerosis, rheumatoid arthritis, diabetes, influenza, many types of cancer and adverse pregnancy outcomes. Solar radiation induces nitric oxide release in tissue and immediate pigment darkening which certainly play important roles, although these are still unknown. Action spectra relevant for health are described. We will also review what is known about spectral and intensity variations of terrestrial solar radiation as well as its penetration through the atmosphere and into human skin and tissue.

  8. Gallium arsenide solar cell radiation damage study

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

  9. Inward diffusion and loss of radiation belt protons

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Baker, D. N.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Hudson, M. K.; Kress, B. T.

    2016-03-01

    Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at fixed values of the first two adiabatic invariants. It is postulated that these protons were trapped with enhanced efficiency during the 7 March 2012 solar proton event. A model that includes radial diffusion, along with known trapped proton source and loss processes, shows that the observed average rate of increase near L = 2 is predicted by the same model diffusion coefficient that is required to form the entire proton radiation belt, down to low L, over an extended (˜103 year) interval. A slower intensity decrease for lower energies near L = 1.5 may also be caused by inward diffusion, though it is faster than predicted by the model. Higher-energy (≳40 MeV) protons near the L = 1.5 intensity maximum are from cosmic ray albedo neutron decay. Their observed intensity is lower than expected by a factor ˜2, but the discrepancy is resolved by adding an unspecified loss process to the model with a mean lifetime ˜120 years.

  10. 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.

  11. Workshop Report on Managing Solar Radiation

    NASA Technical Reports Server (NTRS)

    Lane, Lee (Compiler); Caldeira, Ken (Compiler); Chatfield, Robert (Compiler); Langhoff, Stephanie (Compiler)

    2007-01-01

    The basic concept of managing Earth's radiation budget is to reduce the amount of incoming solar radiation absorbed by the Earth so as to counterbalance the heating of the Earth that would otherwise result from the accumulation of greenhouse gases. The workshop did not seek to decide whether or under what circumstances solar radiation management should be deployed or which strategies or technologies might be best, if it were deployed. Rather, the workshop focused on defining what kinds of information might be most valuable in allowing policy makers more knowledgeably to address the various options for solar radiation management.

  12. Coordinated weather balloon solar radiation measurements during a solar eclipse.

    PubMed

    Harrison, R G; Marlton, G J; Williams, P D; Nicoll, K A

    2016-09-28

    Solar eclipses provide a rapidly changing solar radiation environment. These changes can be studied using simple photodiode sensors, if the radiation reaching the sensors is unaffected by cloud. Transporting the sensors aloft using standard meteorological instrument packages modified to carry extra sensors, provides one promising but hitherto unexploited possibility for making solar eclipse radiation measurements. For the 20 March 2015 solar eclipse, a coordinated campaign of balloon-carried solar radiation measurements was undertaken from Reading (51.44°N, 0.94°W), Lerwick (60.15°N, 1.13°W) and Reykjavik (64.13°N, 21.90°W), straddling the path of the eclipse. The balloons reached sufficient altitude at the eclipse time for eclipse-induced variations in solar radiation and solar limb darkening to be measured above cloud. Because the sensor platforms were free to swing, techniques have been evaluated to correct the measurements for their changing orientation. In the swing-averaged technique, the mean value across a set of swings was used to approximate the radiation falling on a horizontal surface; in the swing-maximum technique, the direct beam was estimated by assuming that the maximum solar radiation during a swing occurs when the photodiode sensing surface becomes normal to the direction of the solar beam. Both approaches, essentially independent, give values that agree with theoretical expectations for the eclipse-induced radiation changes.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'. PMID:27550757

  13. Coordinated weather balloon solar radiation measurements during a solar eclipse

    PubMed Central

    2016-01-01

    Solar eclipses provide a rapidly changing solar radiation environment. These changes can be studied using simple photodiode sensors, if the radiation reaching the sensors is unaffected by cloud. Transporting the sensors aloft using standard meteorological instrument packages modified to carry extra sensors, provides one promising but hitherto unexploited possibility for making solar eclipse radiation measurements. For the 20 March 2015 solar eclipse, a coordinated campaign of balloon-carried solar radiation measurements was undertaken from Reading (51.44°N, 0.94°W), Lerwick (60.15°N, 1.13°W) and Reykjavik (64.13°N, 21.90°W), straddling the path of the eclipse. The balloons reached sufficient altitude at the eclipse time for eclipse-induced variations in solar radiation and solar limb darkening to be measured above cloud. Because the sensor platforms were free to swing, techniques have been evaluated to correct the measurements for their changing orientation. In the swing-averaged technique, the mean value across a set of swings was used to approximate the radiation falling on a horizontal surface; in the swing-maximum technique, the direct beam was estimated by assuming that the maximum solar radiation during a swing occurs when the photodiode sensing surface becomes normal to the direction of the solar beam. Both approaches, essentially independent, give values that agree with theoretical expectations for the eclipse-induced radiation changes. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’. PMID:27550757

  14. Coordinated weather balloon solar radiation measurements during a solar eclipse.

    PubMed

    Harrison, R G; Marlton, G J; Williams, P D; Nicoll, K A

    2016-09-28

    Solar eclipses provide a rapidly changing solar radiation environment. These changes can be studied using simple photodiode sensors, if the radiation reaching the sensors is unaffected by cloud. Transporting the sensors aloft using standard meteorological instrument packages modified to carry extra sensors, provides one promising but hitherto unexploited possibility for making solar eclipse radiation measurements. For the 20 March 2015 solar eclipse, a coordinated campaign of balloon-carried solar radiation measurements was undertaken from Reading (51.44°N, 0.94°W), Lerwick (60.15°N, 1.13°W) and Reykjavik (64.13°N, 21.90°W), straddling the path of the eclipse. The balloons reached sufficient altitude at the eclipse time for eclipse-induced variations in solar radiation and solar limb darkening to be measured above cloud. Because the sensor platforms were free to swing, techniques have been evaluated to correct the measurements for their changing orientation. In the swing-averaged technique, the mean value across a set of swings was used to approximate the radiation falling on a horizontal surface; in the swing-maximum technique, the direct beam was estimated by assuming that the maximum solar radiation during a swing occurs when the photodiode sensing surface becomes normal to the direction of the solar beam. Both approaches, essentially independent, give values that agree with theoretical expectations for the eclipse-induced radiation changes.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.

  15. Adaptive Implicit Non-Equilibrium Radiation Diffusion

    SciTech Connect

    Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael

    2013-01-01

    We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

  16. Integrated Solar Concentrator and Shielded Radiator

    NASA Technical Reports Server (NTRS)

    Clark, David Larry

    2010-01-01

    A shielded radiator is integrated within a solar concentrator for applications that require protection from high ambient temperatures with little convective heat transfer. This innovation uses a reflective surface to deflect ambient thermal radiation, shielding the radiator. The interior of the shield is also reflective to provide a view factor to deep space. A key feature of the shield is the parabolic shape that focuses incoming solar radiation to a line above the radiator along the length of the trough. This keeps the solar energy from adding to the radiator load. By placing solar cells along this focal line, the concentration of solar energy reduces the number and mass of required cells. By shielding the radiator, the effective reject temperature is much lower, allowing lower radiator temperatures. This is particularly important for lower-temperature processes, like habitat heat rejection and fuel cell operations where a high radiator temperature is not feasible. Adding the solar cells in the focal line uses the concentrating effect of the shield to advantage to accomplish two processes with a single device. This shield can be a deployable, lightweight Mylar structure for compact transport.

  17. Solar Radiation Research Laboratory (Poster)

    SciTech Connect

    Stoffel, T.; Andreas, A.; Reda, I.; Dooraghi, M.; Habte, A.; Kutchenreiter, M.; Wilcox, S.

    2012-07-01

    SunShot Initiative awardee posters describing the different technologies within the four subprograms of the DOE Solar Program (Photovoltaics, Concentrating Solar Power, Soft Costs, and Systems Integration).

  18. Gas phase radiative effects in diffusion flames

    NASA Astrophysics Data System (ADS)

    Bedir, Hasan

    Several radiation models are evaluated for a stagnation point diffusion flame of a solid fuel in terms of accuracy and computational time. Narrowband, wideband, spectral line weighted sum of gray gases (SLWSGG), and gray gas models are included in the comparison. Radiative heat flux predictions by the nongray narrowband, wideband, and SLWSGG models are found to be in good agreement with each other, whereas the gray gas models are found to be inaccurate. The narrowband model, the most complex among the models evaluated, is then applied first to a solid fuel and second to a pure gaseous diffusion flame. A polymethylmethacrylate (PMMA) diffusion flame in a stagnation point geometry is solved with the narrowband model with COsb2, Hsb2O, and MMA vapor included in participating species. A detailed account of the emission and absorption from these species as well as the radiative heat fluxes are given as a function of the stretch rate. It is found that at low stretch rate the importance of radiation is increased due to an increase in the optical thickness, and a decrease in the conductive heat flux. Results show that COsb2 is the biggest emitter and absorber in the flame, MMA vapor is the second and Hsb2O is the least important. A pure gaseous flame in an opposed jet configuration is solved with the narrowband radiation model with CO as the fuel, and Osb2 as the oxidizer. Detailed. chemical kinetics and transport are incorporated into the combustion model with the use of the CHEMKIN and TRANSPORT software packages. The governing equations are solved with a modified version of the OPPDIF code. Dry and wet CO flames as well as COsb2 dilution are studied. Comparison of the results with and without the consideration of radiation reveals that the radiation is important for the whole flammable range of dry CO flames and for the low stretch rates of wet flames. Without the consideration of radiation the temperature and the species mole fractions (especially of minor species

  19. 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.

  20. Solar radiation reduction by water and dust in the area of Thessaloniki

    SciTech Connect

    Sahsamanoglou, H.S.; Bloutsos, A.A. )

    1989-01-01

    In the present work, an attempt is made to present the realistic condition of the atmosphere over the city of Thessaloniki by comparing the direct solar radiation reaching the city centre with the solar radiation reaching the rural areas. The comparison is made possible by making use of the values of direct solar radiation and of turbidity factors, such as the Linke turbidity factor Tg or the Angstrom turbidity coefficient {beta}. The values of direct solar radiation which were measured inside the city were significantly lower than the ones measured out in the rural area. It has been found that the direct solar radiation in the city exhibits a reduction of the order of 10-20%. The reduced values of direct solar radiation measured inside the city are sometimes due to the increased concentration of dust particles and sometimes due to the increased quantities of water vapor coming from Thermaikos bay and diffused in the atmosphere.

  1. Diffusion length measurements in solar cells: An analysis and comparison of techniques

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Khan, A. A.; Soukup, R. J.; Hermann, A. M.

    1982-01-01

    A brief review of the major techniques for measuring minority carrier diffusion lengths in solar cells is given. Emphasis is placed on comparing limits of applicability for each method, especially as applied to silicon cells or to gallium arsenide cells, including the effects of radiation damage.

  2. Decadal Variations in Surface Solar Radiation

    NASA Astrophysics Data System (ADS)

    Wild, M.

    2007-05-01

    Satellite estimates provide some information on the amount of solar radiation absorbed by the planet back to the 1980s. The amount of solar radiation reaching the Earth surface can be traced further back in time, untill the 1960s at widespread locations and into the first half of the 20th Century at selected sites. These surface sites suggest significant decadal variations in solar radiation incident at the surface, with indication for a widespread dimming from the 1960s up to the mid 1980s, and a recovery thereafter. Indications for changes in surface solar radiation may also be seen in observatinal records of diurnal temperature range, which provide a better global coverage than the radiation measurrements. Trends in diurnal temperature ranges over global land surfaces show, after decades of decline, a distinct tendency to level off since the mid 1980s. This provides further support for a significant shift in surface solar radiation during the 1980s. There is evidence that the changes in surface solar radiation are linked to associated changes in atmospheric aerosol. Variations in scattering sulfur and absorbing black carbon aerosols are in line with the variations in surface solar radiation. This suggests that at least a part of the variations in surface solar radiation should also be seen in the clear sky planetary albedo. Model simulations with a GCM which includes a sophisticated interactive treatment of aerosols and their emission histories (ECHAM5 HAM), can be used to address this issue. The model is shown to be capable of reproducing the reversal from dimming to brightening under cloud-free conditions in many parts of the world, in line with observational evidence. Associated changes can also be seen in the clear sky planetary albedo, albeit of smaller magnitude.

  3. Global and diffuse solar irradiances in urban and rural areas in southeast Brazil

    NASA Astrophysics Data System (ADS)

    Codato, G.; Oliveira, A. P.; Soares, J.; Escobedo, J. F.; Gomes, E. N.; Pai, A. D.

    2008-06-01

    The seasonal evolution of daily and hourly values of global and diffuse solar radiation at the surface are compared for the cities of São Paulo and Botucatu, both located in Southeast Brazil and representative of urban and rural areas, respectively. The comparisons are based on measurements of global and diffuse solar irradiance carried out at the surface during a six year simultaneous period in these two cities. Despite the similar latitude and altitude, the seasonal evolution of daily values indicate that São Paulo receives, during clear sky days, 7.8% less global irradiance in August and 5.1% less in June than Botucatu. On the other hand, São Paulo receives, during clear sky days, 3.6% more diffuse irradiance in August and 15.6% more in June than Botucatu. The seasonal variation of the diurnal cycle confirms these differences and indicates that they are more pronounced during the afternoon. The regional differences are related to the distance from the Atlantic Ocean, systematic penetration of the sea breeze and daytime evolution of the particulate matter in São Paulo. An important mechanism controlling the spatial distribution of solar radiation, on a regional scale, is the sea breeze penetration in São Paulo, bringing moisture and maritime aerosol that in turn further increases the solar radiation scattering due to pollution and further reduces the intensity of the direct component of solar radiation at the surface. Surprisingly, under clear sky conditions the atmospheric attenuation of solar radiation in Botucatu during winter the biomass burning period due to the sugar cane harvest is equivalent to that at São Paulo City, indicating that the contamination during sugar cane harvest in Southeast Brazil has a large impact in the solar radiation field at the surface.

  4. Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation.

    PubMed

    Kume, Atsushi; Akitsu, Tomoko; Nasahara, Kenlo Nishida

    2016-07-01

    The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (μmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies. PMID:26943164

  5. Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation.

    PubMed

    Kume, Atsushi; Akitsu, Tomoko; Nasahara, Kenlo Nishida

    2016-07-01

    The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (μmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies.

  6. High Radiation Resistance IMM Solar Cell

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  7. Estimating worldwide solar radiation resources on a 40km grid

    SciTech Connect

    Maxwell, E.L.; George, R.L.; Brady, E.H.

    1996-11-01

    During 1995, the National Renewable Energy Laboratory (NREL), initiated the Data Grid Task under the auspices of DOE`s Resource Assessment Program. A data grid is a framework of uniformly spaced locations (grid points) for which data are available. Estimates of monthly averages of direct normal, diffuse horizontal, and global horizontal daily-total solar radiation energy (kWh/m{sup 2}) are being made for each point on a grid covering the US, Mexico, the Caribbean, and southern Canada. The grid points are separated by approximately 40 km. Using interpolation methods, the digital data grid can be used to estimate solar resources at any location. The most encouraging result to date has been the location of sources providing worldwide data for most of the input parameters required for modeling daily total solar radiation. This is a multiyear task expected to continue through the rest of this century.

  8. Effects of solar radiation on glass

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Kinser, Donald L.

    1991-01-01

    The effects of solar radiation of selected glasses are reported. Optical property degradation is studied using UV-Vis spectrophotometry. Strength changes are measured using a concentric ring bend test. Direct fracture toughness measurements using an indentation test are planned.

  9. Spectrometer system for diffuse extreme ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Labov, Simon E.

    1989-01-01

    A unique grazing incidence spectrometer system has been designed to study diffuse line emission between 80 and 650 A with 10-30 A resolution. The minimum detectable emission line strength during a 5-min observation ranges from 100-2000 ph/sq cm sec str. The instrument uses mechanically ruled reflection gratings placed in front of a linear array of mirrors. These mirrors focus the spectral image on microchannel plate detectors located behind thin filters. The field of view is 40 min of arc by 15 deg, and there is no spatial imaging. This instrument has been fabricated, calibrated, and successfully flown on a sounding rocket to observe the astronomical background radiation.

  10. Radiation degradation of solar cell arrays

    NASA Technical Reports Server (NTRS)

    Hill, C. W.

    1975-01-01

    A method of incorporating a detailed solar cell radiation degradation model into a convenient computational scheme suitable for the solar electric propulsion system is outlined. The study shows that several existing codes may be applied in sequence to solve the problem.

  11. Commission 12: Solar Radiation and Structure

    NASA Astrophysics Data System (ADS)

    Kosovichev, Alexander; Cauzzi, Gianna; Pillet, Valentin Martinez; Asplund, Martin; Brandenburg, Axel; Chou, Dean-Yi; Christensen-Dalsgaard, Jorgen; Gan, Weiqun; Kuznetsov, Vladimir D.; Rovira, Marta G.; Shchukina, Nataliya; Venkatakrishnan, P.

    2012-04-01

    Commission 12 of the International Astronomical Union encompasses investigations of the internal structure and dynamics of the Sun, mostly accessible through the techniques of local and global helioseismology, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. The Commission sees participation of over 350 scientists worldwide.

  12. Solar ultraviolet radiation: definitions and terminology.

    PubMed

    Matts, Paul J

    2006-01-01

    In the rapidly developing field of photobiology as it relates to solar ultraviolet radiation (UVR), there is a need as never before to ensure that definitions and terminology are current, correct, and standard. This article provides a basic definition of UVR; a review of correct UVR radiometric symbols, units, and nomenclature; defines extraterrestrial and terrestrial solar UVR; and reviews the measurement of biologically effective dose of solar UVR in humans.

  13. Solar ultraviolet radiation: definitions and terminology.

    PubMed

    Matts, Paul J

    2006-01-01

    In the rapidly developing field of photobiology as it relates to solar ultraviolet radiation (UVR), there is a need as never before to ensure that definitions and terminology are current, correct, and standard. This article provides a basic definition of UVR; a review of correct UVR radiometric symbols, units, and nomenclature; defines extraterrestrial and terrestrial solar UVR; and reviews the measurement of biologically effective dose of solar UVR in humans. PMID:16311162

  14. On-orbit characterization of the VIIRS solar diffuser and solar diffuser screen.

    PubMed

    Sun, Junqiang; Wang, Menghua

    2015-01-10

    We analyze bidirectional reflectance factors (BRF) of the solar diffuser (SD) and vignetting function (VF) of the SD screen (SDS) for on-board calibration of the visible infrared imaging radiometer suite (VIIRS). Specific focus is placed on the products of the BRF and VF, which are the main inputs for calibration of the SD and its accompanying solar diffuser stability monitor (SDSM), which tracks SD degradation. A set of 14 spacecraft yaw maneuvers for the Suomi National Polar-Orbiting Partnership satellite, which houses the VIIRS instrument, was carefully planned and carried out over many orbits to provide the necessary information on the dependence of VIIRS instrument response on solar angles. Along with the prelaunch measurements for the SDS VF and SD BRF, the absolute form of the BRF-VF product is determined for each of the reflective solar bands (RSB) and the SDSM detectors. Consequently, the absolute form of the SDS VF also is obtained from the RSB and SDSM detectors using the yaw maneuver data. The results show that the BRF-VF product for an RSB is independent of the detector, gain status, and half-angle mirror side. The derived VFs from the RSB and the SDSM detectors also show reasonable agreement with each other, as well as with the prelaunch VF measurements, and further demonstrate only geometrical dependence, which, in this work, is characterized by solar angles. The derived calibration coefficients, called the F-factors, from the application of the derived functions in this study show a significantly improved pattern. A small band-dependent residual seasonal fluctuation on the level of ∼0.2%-0.4% remains in the F-factors for each RSB and is further improved by a corrective function with linear dependence on the solar azimuth angle in the nominal attitude instrument coordinate system to the VF. For satellite ocean color remote sensing, on-orbit instrument calibration and characterization are particularly important for producing accurate and consistent

  15. Radiation transfer in plant canopies - Scattering of solar radiation and canopy reflectance

    NASA Technical Reports Server (NTRS)

    Verstraete, Michel M.

    1988-01-01

    The one-dimensional vertical model of radiation transfer in a plant canopy described by Verstraete (1987) is extended to account for the transfer of diffuse radiation. This improved model computes the absorption and scattering of both visible and near-infrared radiation in a multilayer canopy as a function of solar position and leaf orientation distribution. Multiple scattering is allowed, and the spectral reflectance of the vegetation stand is predicted. The results of the model are compared to those of other models and actual observations.

  16. Ground-based monitoring of solar radiation in Moldova

    NASA Astrophysics Data System (ADS)

    Aculinin, Alexandr; Smicov, Vladimir

    2010-05-01

    Integrated measurements of solar radiation in Kishinev, Moldova have been started by Atmospheric Research Group (ARG) at the Institute of Applied Physics from 2003. Direct, diffuse and total components of solar and atmospheric long-wave radiation are measured by using of the radiometric complex at the ground-based solar radiation monitoring station. Measurements are fulfilled at the stationary and moving platforms equipped with the set of 9 broadband solar radiation sensors overlapping wavelength range from UV-B to IR. Detailed description of the station can be found at the site http://arg.phys.asm.md. Ground station is placed in an urban environment of Kishinev city (47.00N; 28.56E). Summary of observation data acquired at the station in the course of short-term period from 2004 to 2009 are presented below. Solar radiation measurements were fulfilled by using CM11(280-3000 nm) and CH1 sensors (Kipp&Zonen). In the course of a year maximum and minimum of monthly sums of total radiation was ~706.4 MJm-2 in June and ~82.1MJm-2 in December, respectively. Monthly sums of direct solar radiation (on horizontal plane) show the maximum and minimum values of the order ~456.9 MJm-2 in July and ~25.5MJm-2 in December, respectively. In an average, within a year should be marked the predominance of direct radiation over the scattered radiation, 51% and 49%, respectively. In the course of a year, the percentage contribution of the direct radiation into the total radiation is ~55-65% from May to September. In the remaining months, the percentage contribution decreases and takes the minimum value of ~ 28% in December. In an average, annual sum of total solar radiation is ~4679.9 MJm-2. For the period from April to September accounts for ~76% of the annual amount of total radiation. Annual sum of sunshine duration accounts for ~2149 hours, which is of ~ 48% from the possible sunshine duration. In an average, within a year maximum and minimum of sunshine duration is ~ 304 hours in

  17. RADIATIVE HEATING OF THE SOLAR CORONA

    SciTech Connect

    Moran, Thomas G.

    2011-10-20

    We investigate the effect of solar visible and infrared radiation on electrons in the Sun's atmosphere using a Monte Carlo simulation of the wave-particle interaction and conclude that sunlight provides at least 40% and possibly all of the power required to heat the corona, with the exception of dense magnetic flux loops. The simulation uses a radiation waveform comprising 100 frequency components spanning the solar blackbody spectrum. Coronal electrons are heated in a stochastic manner by low coherence solar electromagnetic radiation. The wave 'coherence time' and 'coherence volume' for each component is determined from optical theory. The low coherence of solar radiation allows moving electrons to gain energy from the chaotic wave field which imparts multiple random velocity 'kicks' to these particles causing their velocity distribution to broaden or heat. Monte Carlo simulations of broadband solar radiative heating on ensembles of 1000 electrons show heating at per particle levels of 4.0 x 10{sup -21} to 4.0 x 10{sup -20} W, as compared with non-loop radiative loss rates of {approx}1 x 10{sup -20} W per electron. Since radiative losses comprise nearly all of the power losses in the corona, sunlight alone can explain the elevated temperatures in this region. The volume electron heating rate is proportional to density, and protons are assumed to be heated either by plasma waves or through collisions with electrons.

  18. Solar radiation transmission in and around canopy gaps in an uneven-aged Nothofagus betuloides forest.

    PubMed

    Promis, Alvaro; Schindler, Dirk; Reif, Albert; Cruz, Gustavo

    2009-07-01

    The transmission of direct, diffuse and global solar radiation in and around canopy gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006-March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest canopy, but also by low angles of the sun's path. The below-canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the canopy gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-canopy solar radiation in the forest. The model that best fit the transmitted below-canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable (R (2) = 0.263). Both diffuse and global solar radiation were very sensitive to canopy openness, and for both cases a quadratic model provided the best fit for these data (R (2) = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.

  19. Solar Radiation and Climate Experiment (SORCE) Satellite

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This is a close-up of the NASA-sponsored Solar Radiation and Climate Experiment (SORCE) Satellite. The SORCE mission, launched aboard a Pegasus rocket January 25, 2003, will provide state of the art measurements of incoming x-ray, ultraviolet, visible, near-infrared, and total solar radiation. Critical to studies of the Sun and its effect on our Earth system and mankind, SORCE will provide measurements that specifically address long-term climate change, natural variability and enhanced climate prediction, and atmospheric ozone and UV-B radiation. Orbiting around the Earth accumulating solar data, SORCE measures the Sun's output with the use of state-of-the-art radiometers, spectrometers, photodiodes, detectors, and bolo meters engineered into instruments mounted on a satellite observatory. SORCE is carrying 4 instruments: The Total Irradiance Monitor (TIM); the Solar Stellar Irradiance Comparison Experiment (SOLSTICE); the Spectral Irradiance Monitor (SIM); and the XUV Photometer System (XPS).

  20. Application of semiconductor diffusants to solar cells by screen printing

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr.; Mazaris, G. A.; Scudder, L. R. (Inventor)

    1978-01-01

    Diffusants were applied onto semiconductor solar cell substrates, using screen printing techniques. The method was applicable to square and rectangular cells and can be used to apply dopants of opposite types to the front and back of the substrate. Then, simultaneous diffusion of both dopants can be performed with a single furnace pass.

  1. The engineering analysis of solar radiation

    NASA Technical Reports Server (NTRS)

    Reid, M. S.; Hamilton, C. L.; Hester, O. V.

    1978-01-01

    A necessary precursor to construction of well-designed, efficient, and economically viable solar energy systems is the engineering analysis not only of the systems themselves but also of the solar radiation that will drive them. This paper presents the first steps in such an analysis to support the design of solar thermal power systems. A rationale for development of an integrated approach to this analysis is outlined, and elements of the approach are described. A dynamic computer simulation of a conceptual system was employed in an initial sensitivity analysis to explore how performance estimates might be affected by the precision and amount of detail in solar radiation data used as model input. A measurement program, including instrumentation, used to characterize precisely and in detail the solar resource at one location is described as is a probabilistic model derived from it, for predicting insolation as a function of time.

  2. Solar radiation decreases parasitism in Daphnia.

    PubMed

    Overholt, Erin P; Hall, Spencer R; Williamson, Craig E; Meikle, Claire K; Duffy, Meghan A; Cáceres, Carla E

    2012-01-01

    Climate change and variation in atmospheric ozone are influencing the intensity of ultraviolet radiation (UVR) reaching ecosystems. Changing UVR regimes, in turn, may alter epidemics of infectious disease. This possibility hinges on the sensitivity of epidemiologically relevant traits of host and parasite to UVR. We address this issue using a planktonic system (a zooplankton host, Daphnia dentifera, and its virulent fungal parasite, Metschnikowia bicuspidata). Controlled laboratory experiments, coupled with in situ field incubations of spores, revealed that quite low levels of UVR (as well as longer wavelength light) sharply reduced the infectivity of fungal spores but did not affect host susceptibility to infection. The parasite's sensitivity to solar radiation may underlie patterns in a lake survey: higher penetration of solar radiation into lakes correlated with smaller epidemics that started later in autumn (as incident sunlight declined). Thus, solar radiation, by diminishing infectivity of the parasite, may potently reduce disease. PMID:22034950

  3. LAGEOS Solar Radiation Force: Contribution from Cube-Corner Retroreflection

    NASA Astrophysics Data System (ADS)

    Slabinski, Victor J.

    2016-05-01

    The surface of a spherical LAGEOS satellite contains 426 Cube Corner Reflectors (CCRs) for the retro-reflection of incident laser ranging beams back to their source. For practical reasons, the number of CCRs is finite, so their distribution over the surface is not perfectly uniform.At any time, the ~9 CCRs near the sub-solar point on the LAGEOS surface will also retroreflect incident sunlight back toward the Sun. This concentration of reflected sunlight into a parallel beam increases the resulting radiation force on the satellite over what occurs for the usual broad-beam specular and diffuse reflection by ordinary surfaces. Because of the non-uniform CCR distribution, the retroreflection of sunlight (and hence the solar radiation force on the satellite) varies with the Sun aspect angle, even when averaged over the spin period. The Sun aspect angle is the co-latitude of the sub-solar surface point measured from the spin pole.We use ray tracing of sunlight through the CCRs to determine the Sun angle dependence of the solar radiation force and the resulting variation in secular perturbation rates for the LAGEOS orbit, especially for the eccentricity elements. We investigate the possibility of using the observed variations in the eccentricity vector as a check on the spacecraft spin-axis attitude. Attitude information is important for computing radiation-force perturbations to the orbit node when determining the Lense-Thirring effect.

  4. Solar Position Algorithm for Solar Radiation Applications (Revised)

    SciTech Connect

    Reda, I.; Andreas, A.

    2008-01-01

    This report is a step-by-step procedure for implementing an algorithm to calculate the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of ?0.0003/. It is written in a step-by-step format to simplify otherwise complicated steps, with a focus on the sun instead of the planets and stars in general. The algorithm is written in such a way to accommodate solar radiation applications.

  5. Diffuse radiation increases global ecosystem-level water-use efficiency

    NASA Astrophysics Data System (ADS)

    Moffat, A. M.; Reichstein, M.; Cescatti, A.; Knohl, A.; Zaehle, S.

    2012-12-01

    Current environmental changes lead not only to rising atmospheric CO2 levels and air temperature but also to changes in air pollution and thus the light quality of the solar radiation reaching the land-surface. While rising CO2 levels are thought to enhance photosynthesis and closure of stomata, thus leading to relative water savings, the effect of diffuse radiation on transpiration by plants is less clear. It has been speculated that the stimulation of photosynthesis by increased levels of diffuse light may be counteracted by higher transpiration and consequently water depletion and drought stress. Ultimately, in water co-limited systems, the overall effect of diffuse radiation will depend on the sensitivity of canopy transpiration versus photosynthesis to diffuse light, i.e. whether water-use efficiency changes with relative levels of diffuse light. Our study shows that water-use efficiency increases significantly with higher fractions of diffuse light. It uses the ecosystem-atmosphere gas-exchange observations obtained with the eddy covariance method at 29 flux tower sites. In contrast to previous global studies, the analysis is based directly on measurements of diffuse radiation. Its effect on water-use efficiency was derived by analyzing the multivariate response of carbon and water fluxes to radiation and air humidity using a purely empirical approach based on artificial neural networks. We infer that per unit change of diffuse fraction the water-use efficiency increases up to 40% depending on diffuse fraction levels and ecosystem type. Hence, in regions with increasing diffuse radiation positive effects on primary production are expected even under conditions where water is co-limiting productivity.

  6. Obliquity Modulation of the Incoming Solar Radiation

    NASA Technical Reports Server (NTRS)

    Liu, Han-Shou; Smith, David E. (Technical Monitor)

    2001-01-01

    Based on a basic principle of orbital resonance, we have identified a huge deficit of solar radiation induced by the combined amplitude and frequency modulation of the Earth's obliquity as possibly the causal mechanism for ice age glaciation. Including this modulation effect on solar radiation, we have performed model simulations of climate change for the past 2 million years. Simulation results show that: (1) For the past 1 million years, temperature fluctuation cycles were dominated by a 100-Kyr period due to amplitude-frequency resonance effect of the obliquity; (2) From 2 to 1 million years ago, the amplitude-frequency interactions. of the obliquity were so weak that they were not able to stimulate a resonance effect on solar radiation; (3) Amplitude and frequency modulation analysis on solar radiation provides a series of resonance in the incoming solar radiation which may shift the glaciation cycles from 41-Kyr to 100-Kyr about 0.9 million years ago. These results are in good agreement with the marine and continental paleoclimate records. Thus, the proposed climate response to the combined amplitude and frequency modulation of the Earth's obliquity may be the key to understanding the glaciation puzzles in paleoclimatology.

  7. Diffuse galactic annihilation radiation from supernova nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Higdon, J. C.

    1985-01-01

    The propagation of MeV positrons in the outer ejecta of type I supernovae was investigated. It was found that the positrons created at times of approx 100 days propagated along magnetic field lines in the outer ejecta without any appreciable pitch-angle scattering or excitation of hydromagnetic waves. The lack of significant pitch-angle scattering is well consistent with models of wave excitation and scattering by resonant interactions. This occurs because time periods to scatter the particles or to excite waves are significantly longer than escape times. Thus it is expected that, when positrons are not coupled to the ejecta by Coulomb collisions, they escape from the relatively cold, dense ejecta and reside predominantly in the tenuous, hotter, shock-heated interstellar gas. In the tenuous shock-heated gas the positron lifetime against annihilation is much greater than lifetimes in the dense ejectra. Thus the production of steady-state diffuse annihilation radiation by some fraction of these escaped positrons seems probable.

  8. Orbiter radiator panel solar focusing test

    NASA Technical Reports Server (NTRS)

    Howell, H. R.

    1982-01-01

    A test was conducted to determine the solar reflections from the Orbiter radiator panels. A one-tenth scale model of the forward and mid-forward radiator panels in the deployed position was utilized in the test. Test data was obtained to define the reflected one-sun envelope for the embossed silver/Teflon radiator coating. The effects of the double contour on the forward radiator panels were included in the test. Solar concentrations of 2 suns were measured and the one-sun envelope was found to extend approximately 86 inches above the radiator panel. A limited amount of test data was also obtained for the radiator panels with the smooth silver/Teflon coating to support the planned EVA on the Orbiter STS-5 flight. Reflected solar flux concentrations as high as 8 suns were observed with the smooth coating and the one-sun envelope was determined to extend 195 inches above the panel. It is recommended that additional testing be conducted to define the reflected solar environment beyond the one-sun boundary.

  9. Exospheric cleaning of the Earth Radiation Budget solar radiometer during solar maximum

    NASA Technical Reports Server (NTRS)

    Predmore, R. E.; Jacobowitz, H.; Hickey, J. R.

    1983-01-01

    Anomalous behavior of the Earth Sensor Assemblies (ESA) had been observed on the Defense Meteorological Satellite Program (DMSP) 5D/1 satellites and the Tiros-N satellite. The present investigation is concerned with the reasons for the observed phenomena. Degradation of the Earth Radiation Budget (ERB) solar channels and the Solar Backscatter Ultraviolet and Total Ozone Mapping Spectrometer (SBUV/TOMS) diffuser plate is attributed to transmission or reflection loss originating from the growth of an organic film by photolytic polymerization. Simultaneous degradation of the ESA interference filter coated lenses facing the flight direction and the recovery of the ERB solar channels on Nimbus 6 and 7 is caused by a reaction with the increase in the exospheric atmospheric density caused by solar maximum.

  10. Evaluating solar radiation on a tilted surfaces - a study case in Timis (Romania)

    NASA Astrophysics Data System (ADS)

    Vasar, C.; Prostean, O.; Prostean, G.

    2016-02-01

    In the last years the usage of solar energy has grown considerably in Romania, as well as in Europe, stimulated by various factors as government programs, green pricing policies, decreasing of photovoltaic components cost etc. Also, the rising demand of using Solar Energy Conversion Systems (SECS) is driven by the desire of individuals or companies to obtain energy from a clean renewable source. In many applications, remote consumers far from other energetic grids can use solar systems more cost-effectively than extending the grid to reach the location. Usually the solar energy is measured or forecast on horizontal surface, but in SECS there is needed the total solar radiation incident on the collector surface, that is oriented in a position that maximize the harvested energy. There are many models that convert the solar radiation from horizontal surface to a tilted surface, but they use empirical coefficients and the accuracy is influenced by different facts as geographical location or sky conditions. Such models were used considering measured values for solar radiation on horizontal plane, in the western part of Romania. Hourly values measured for global solar irradiation on the horizontal plane, diffuse solar irradiation on the horizontal plane and reflected solar irradiation by ground are used to compute the total solar radiation incident on different tilted surfaces. The calculated incident radiation is then compared with the real radiation measured on tilted surface in order to evaluate the performance of the considered conversion models.

  11. Particulate and solar radiation stable coating for spacecraft

    NASA Technical Reports Server (NTRS)

    Slemp, W. S. (Inventor)

    1977-01-01

    A laminate thermal control coating for spacecraft comprising a layer of solar radiation stable film, a layer of particulate radiation stable film applied to the upper surface of the solar radiation stable film, and a layer of reflecting material applied to the lower surface of the solar radiation stable film was described. The coating experiences no increase in solar radiation absorptance (the proportion of radiant energy absorbed) upon exposure to particulate or solar radiation as the particulate radiation is substantially absorbed in the particulate radiation stable layer and the solar radiation partially absorbed by the particulate radiation stable layer is transmitted by the solar radiation stable film to the reflecting material which reflects it back through the laminate and into space.

  12. LDEF solar cell radiation effects analysis

    NASA Technical Reports Server (NTRS)

    Rives, Carol J.; Azarewicz, Joseph L.; Massengill, Lloyd

    1993-01-01

    Because of the extended time that the Long Duration Exposure Facility (LDEF) mission stayed in space, the solar cells on the satellite experienced greater environments than originally planned. The cells showed an overall degradation in performance that is due to the combined effects of the various space environments. The purpose of this analysis is to calculate the effect of the accumulated radiation on the solar cells, thereby helping Marshall Space Flight Center (MSFC) to unravel the relative power degradation from the different environments.

  13. Fast dynamic processes of solar radiation

    SciTech Connect

    Tomson, Teolan

    2010-02-15

    This paper studies dynamic processes of fast-alternating solar radiation which are assessed by alternation of clouds. Most attention is devoted to clouds of type Cumulus Humilis, identified through visual recognition and/or a specially constructed automatic sensor. One second sampling period was used. Recorded data series were analyzed with regard to duration of illuminated 'windows' between shadows, their stochastic intervals, fronts and the magnitude of increments of solar irradiance. (author)

  14. Hydrogen diffusion in chalcopyrite solar cell materials

    SciTech Connect

    Weidinger, A.; Krauser, J.; Riedle, T.; Klenk, R.; Lux-Steiner, M.C.; Yakushev, M.V.

    1998-12-31

    Hydrogen diffusion in CuInSe{sub 2} single crystals and CuInS{sub 2} thin films was studied by measuring the spreading of implantation profiles upon annealing. Deep implantation with an ion energy of 10 keV and sub-surface implantation with 300 eV were applied. The diffusion coefficients in both materials were found to be in the order of 10{sup {minus}14} to 10{sup {minus}13} cm{sup 2}/s in the temperature range between 400 and 520 K. These fairly low diffusivities are typical for a trap and release transport process rather than intrinsic diffusion of interstitial hydrogen. In the polycrystalline CuInS{sub 2} films, hydrogen leaves the sample through the grain boundaries.

  15. Measurement of solar radiation at the Earth's surface

    NASA Technical Reports Server (NTRS)

    Bartman, F. L.

    1982-01-01

    The characteristics of solar energy arriving at the surface of the Earth are defined and the history of solar measurements in the United States presented. Radiation and meteorological measurements being made at solar energy meteorological research and training sites and calibration procedures used there are outlined. Data illustrating the annual variation in daily solar radiation at Ann Arbor, Michigan and the diurnal variation in radiation at Albuquerque, New Mexico are presented. Direct normal solar radiation received at Albuquerque is contrasted with that received at Maynard, Massachusetts. Average measured global radiation for a period of one year for four locations under clear skies, 50% cloud cover, and 100% cloud cover is given and compared with the solar radiation at the top of the atmosphere. The May distribution of mean daily direct solar radiation and mean daily global solar radiation over the United States is presented. The effects of turbidity on the direct and circumsolar radiation are shown.

  16. Wetlands Evapotranspiration Using Remotely Sensed Solar Radiation

    NASA Astrophysics Data System (ADS)

    Jacobs, J. M.; Myers, D. A.; Anderson, M. C.

    2001-12-01

    The application of remote sensing methods to estimate evapotranspiration has the advantage of good spatial resolution and excellent spatial coverage, but may have the disadvantage of infrequent sampling and considerable expense. The GOES satellites provide enhanced temporal resolution with hourly estimates of solar radiation and have a spatial resolution that is significantly better than that available from most ground-based pyranometer networks. As solar radiation is the primary forcing variable in wetland evapotranspiration, the opportunity to apply GOES satellite data to wetland hydrologic analyses is great. An accuracy assessment of the remote sensing product is important and the subsequent validation of the evapotranspiration estimates are a critical step for the use of this product. A wetland field experiment was conducted in the Paynes Prairie Preserve, North Central Florida during a growing season characterized by significant convective activity. Evapotranspiration and other surface energy balance components of a wet prairie community dominated by Panicum hemitomon (maiden cane), Ptilimnium capillaceum (mock bishop's weed), and Eupatorium capillifolium (dog fennel) were investigated. Incoming solar radiation derived from GOES-8 satellite observations, in combination with local meteorological measurements, were used to model evapotranspiration from a wetland. The satellite solar radiation, derived net radiation and estimated evapotranspiration estimates were compared to measured data at 30-min intervals and daily times scales.

  17. 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/

  18. Modeling Copper Diffusion in Polycrystalline CdTe Solar Cells

    SciTech Connect

    Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Guo, Da; Vasileska, Dragica; Ringhofer, Christain

    2014-06-06

    It is well known that Cu plays an important role in CdTe solar cell performance as a dopant. In this work, a finite-difference method is developed and used to simulate Cu diffusion in CdTe solar cells. In the simulations, which are done on a two-dimensional (2D) domain, the CdTe is assumed to be polycrystalline, with the individual grains separated by grain boundaries. When used to fit experimental Cu concentration data, bulk and grain boundary diffusion coefficients and activation energies for CdTe can be extracted. In the past, diffusion coefficients have been typically obtained by fitting data to simple functional forms of limited validity. By doing full simulations, the simplifying assumptions used in those analytical models are avoided and diffusion parameters can thus be determined more accurately

  19. Asteroseismic tests of element diffusion in solar type stars

    NASA Astrophysics Data System (ADS)

    Théado, S.; Vauclair, S.; Castro, M.; Charpinet, S.; Dolez, N.

    2005-07-01

    Following the success of helioseismology, asteroseismology is now becoming a fundamental tool for penetrating the secrets of the internal structure of stars. In preparation of this new era in stellar physics, we study the effects of element diffusion on the computed frequencies of stellar oscillation modes for main-sequence solar-type stars. As the observed stars will be constrained by their atmospheric parameters, stellar models were computed with different physical inputs (whether including element diffusion or not) and iterated in order to fit the same observables (effective temperature, luminosity, surface chemical composition). The theoretical oscillation frequencies of these models were derived and compared. The results show that diffusion alters the internal structure of the models and their oscillation frequencies in a significant way. Although observational uncertainties in stellar external parameters are still important, comparisons between oscillation frequencies observed with the future space mission COROT and theoretically computed ones might provide evidence for diffusion processes in solar type stars.

  20. Research on gallium arsenide diffused junction solar cells

    NASA Technical Reports Server (NTRS)

    Borrego, J. M.; Ghandi, S. K.

    1984-01-01

    The feasibility of using bulk GaAs for the fabrication of diffused junction solar cells was determined. The effects of thermal processing of GaAs was studied, and the quality of starting bulk GaAs for this purpose was assessed. These cells are to be made by open tube diffusion techniques, and are to be tested for photovoltaic response under AMO conditions.

  1. Diffusion and radiation in magnetized collisionless plasmas with small-scale Whistler turbulence

    NASA Astrophysics Data System (ADS)

    Keenan, Brett D.; Medvedev, Mikhail V.

    2016-04-01

    > Magnetized high-energy-density plasmas can often have strong electromagnetic fluctuations whose correlation scale is smaller than the electron Larmor radius. Radiation from the electrons in such plasmas - which markedly differs from both synchrotron and cyclotron radiation - is tightly related to their energy and pitch-angle diffusion. In this paper, we present a comprehensive theoretical and numerical study of particle transport in cold, `small-scale' Whistler-mode turbulence and its relation to the spectra of radiation simultaneously produced by these particles. We emphasize that this relation is a superb diagnostic tool of laboratory, astrophysical, interplanetary and solar plasmas with a mean magnetic field and strong small-scale turbulence.

  2. SOLAR UV RADIATION AND AQUATIC BIOGEOCHEMISTRY

    EPA Science Inventory

    During the past decade significant interest has developed in the influence of solar UV radiation on biogeochemical cycles in surface waters of lakes and the sea. A major portion of this research has focused on photoreactions of the colored component of dissolved organic matter, ...

  3. MODELING ACUTE EXPOSURE TO SOLAR RADIATION

    EPA Science Inventory

    One of the major technical challenges in calculating solar flux on the human form has been the complexity of the surface geometry (i.e., the surface normal vis a vis the incident radiation). The American Cancer Society reports that over 80% of skin cancers occur on the face, he...

  4. Radiation balances and the solar constant

    NASA Astrophysics Data System (ADS)

    Crommelynck, D.

    1981-07-01

    The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.

  5. Discrete diffusion Monte Carlo for frequency-dependent radiative transfer

    SciTech Connect

    Densmore, Jeffrey D; Kelly, Thompson G; Urbatish, Todd J

    2010-11-17

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.

  6. Radiation Diffusion: An Overview of Physical and Numerical Concepts

    SciTech Connect

    Graziani, F R

    2005-01-14

    An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed

  7. Ultraviolet Radiation in the Solar System

    NASA Astrophysics Data System (ADS)

    Vázquez, M., Hanslmeier, A.

    UV radiation is an important part in the electromagnetic spectrum since the energy of the photons is great enough to produce important chemical reactions in the atmospheres of planets and satellites of our Solar System, thereby affecting the transmission of this radiation to the ground and its physical properties. Scientists have used different techniques (balloons and rockets) to access to the information contained in this radiation, but the pioneering of this new frontier has not been free of dangers. The Sun is our main source of UV radiation and its description occupies the first two chapters of the book. The Earth is the only known location where life exists in a planetary system and therefore where the interaction of living organism with UV radiation can be tested through different epochs and on distinct species. The development of the human technology has affected the natural shield of ozone that protects complex lifeforms against damaging UV irradiation. The formation of the ozone hole and its consequences are described, together with the possible contribution of UV radiation to recent climate changes. Finally, we will discuss the the potential role of ultraviolet light in the development of life on bodies such as Mars, Europa and Titan. The Solar System is not isolated; other external sources can contribute to the enhancement of the UV radiation in our environment. The influence of such events as nearby supernovae and gamma-ray bursts are described, together with the consequences to terrestrial life from such events.

  8. Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

    1993-01-01

    Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

  9. Solar radiation monitoring for high altitude aircraft

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.

    1981-01-01

    Ground-based and satellite-based ionizing radiation monitoring systems are considered as alternative methods for ensuring safe radiation levels for high-altitude aircraft. It is found that ground-based methods are of limited accuracy due to insensitivity to solar particles of energies between the riometer upper cutoff of about 50 MeV and the neutron monitor threshold of about 450 MeV. This energy range is demonstrated to be essential for atmospheric radiation monitoring at high altitude, and must be covered by satellite measurement. On the basis of presently available data, the accuracy to which the incident solar particle flux must be measured by satellite-borne detectors is examined and recommendations are made to establish minimum requirements.

  10. Solar radiation monitoring for high altitude aircraft

    NASA Astrophysics Data System (ADS)

    Wilson, J. W.

    1981-10-01

    Ground-based and satellite-based ionizing radiation monitoring systems are considered as alternative methods for ensuring safe radiation levels for high-altitude aircraft. It is found that ground-based methods are of limited accuracy due to insensitivity to solar particles of energies between the riometer upper cutoff of about 50 MeV and the neutron monitor threshold of about 450 MeV. This energy range is demonstrated to be essential for atmospheric radiation monitoring at high altitude, and must be covered by satellite measurement. On the basis of presently available data, the accuracy to which the incident solar particle flux must be measured by satellite-borne detectors is examined and recommendations are made to establish minimum requirements.

  11. Turning collectors for solar radiation

    DOEpatents

    Barak, Amitzur Z.

    1976-01-01

    A device is provided for turning a solar collector about the polar axis so that the collector is directed toward the sun as the sun tracks the sky each day. It includes two heat-expansive elements and a shadow plate. In the morning a first expansive element is heated, expands to turn the collector to face the sun, while the second expansive element is shaded by the plate. In the afternoon the second element is heated, expands to turn the collector to face the sun, while the first is shaded by the plate.

  12. Diffuser for intravessels radiation based on plastic fiber

    NASA Astrophysics Data System (ADS)

    Pich, Justyna; Grobelny, Andrzej; Beres-Pawlik, Elzbieta

    2006-03-01

    Laser radiation is used in such contemporary medicine as: sport medicine, gynecology etc. Because of many radiations inside the system, there is a need of an element, which allows to supply the place of illness with energy. The dimensions of this element are often small and the one that meets these conditions is diffuser.

  13. Societal Impacts of Solar Electromagnetic Radiation

    NASA Astrophysics Data System (ADS)

    Lean, J. L.

    2000-05-01

    Changes in solar electromagnetic radiation, which occur continuously and at all wavelengths of the spectrum, can have significant societal impacts on a wide range of time scales. Detection of climate change and ozone depletion requires reliable specification of solar-induced processes that mask or exacerbate anthropogenic effects. Living with, and mitigating, climate change and ozone depletion has significant economic, habitat and political impacts of international extent. As an example, taxes to restrict carbon emission may cause undue economic stress if the role of greenhouse gases in global warming is incorrectly diagnosed. Ignoring solar-induced ozone changes in the next century may lead to incorrect assessment of the success of the Montreal Protocol in protecting the ozone layer by limiting the use of ozone-destroying chlorofluorocarbons. Societal infrastructure depends in many ways on space-based technological assets. Communications and navigation for commerce, industry, science and defense rely on satellite signals transmitted through, and reflected by, electrons in the ionosphere. Electron densities change in response to solar flares, and by orders of magnitude in response to EUV and X-ray flux variations during the Sun's 11-year activity cycle. Spacecraft and space debris experience enhanced drag on their orbits when changing EUV radiation causes upper atmosphere densities to increase. Especially affected are spacecraft and debris in lower altitude orbits, such as Iridium-type communication satellites, and the International Space Station (ISS). Proper specification of solar-induced fluctuations in the neutral upper atmosphere can, for example, aid in tracking the ISS and surrounding space debris, reducing the chance of ISS damage from collisions, and maximizing its operations. Aspects of solar electromagnetic radiation variability will be briefly illustrated on a range of time scales, with specific identification of the societal impacts of different

  14. Clothing as solar radiation protection.

    PubMed

    Menter, Julian M; Hatch, Kathryn L

    2003-01-01

    The sun is essential for life. Yet, sunlight can also be a source of such deleterious effects as sunburn, and suntanning, as well as premalignant and malignant lesions. These may all occur in individuals with normal responses to sunlight. In addition, there exist a variety of 'abnormal' photosensitivity responses to sunlight that may result from either endogenous imbalances (e.g. the porphyrias) or from added exogenous factors (e.g. drug photosensitivity). The 'normal' responses to sunlight, by and large, are produced preferentially by UVB (290-320 nm), with minor contribution by UVA (320-400 nm) wavelengths. In contrast, the 'abnormal' photosensitivity responses are, for the most part, elicited predominantly by long UVA and, in some cases, visible light. In the last 20 years or so, considerable attention has been paid to the use of fabrics as photoprotective materials. The vast majority of work in this area has been concerned with fabric protection against sunburn. In addition to in vivo measurement of fabric SPF, in vitro evaluation of fabric UPF has been carried out in numerous laboratories around the world. The UPF is estimated from the wavelength-dependent transmission of the fabric, the solar UV spectrum and the erythemal action spectrum over the wavelength region 290-400 nm. Depending on the fabric, UPF values range from 2 to several thousand. More recently, it has become clear that such environmental influences as laundering, solarization, humidity, wetting and degree of stretching may play a major role in fabric protection. Protection also may be altered by addition of dyes, UV absorbers and fluorescent whitening agents. To date, there have been relatively few studies of fabric protection for endpoints other than sunburn erythema. Yet, many fabrics that provide good protection against sunburn may provide inadequate protection against photosensitization by intrinsic or extrinsic absorbing molecules or against (pre)malignant lesions. Future work should

  15. Solar ultraviolet radiation from cancer induction to cancer prevention: solar ultraviolet radiation and cell biology.

    PubMed

    Tuorkey, Muobarak J

    2015-09-01

    Although decades have elapsed, researchers still debate the benefits and hazards of solar ultraviolet radiation (UVR) exposure. On the one hand, humans derive most of their serum 25-hydroxycholecalciferol [25(OH)D3], which has potent anticancer activity, from solar UVB radiation. On the other hand, people are more aware of the risk of cancer incidence associated with harmful levels of solar UVR from daily sunlight exposure. Epidemiological data strongly implicate UV radiation exposure as a major cause of melanoma and other cancers, as UVR promotes mutations in oncogenes and tumor-suppressor genes. This review highlights the impact of the different mutagenic effects of solar UVR, along with the cellular and carcinogenic challenges with respect to sun exposure.

  16. Solar and thermal radiation in the Venus atmosphere

    NASA Technical Reports Server (NTRS)

    Moroz, V. I.; Ekonomov, A. P.; Moshkin, B. E.; Revercomb, H. E.; Sromovsky, L. A.; Schofield, J. T.

    1985-01-01

    Attention is given to the solar and thermal radiation fields of Venus. Direct measurements and the results of numerical models based on direct measurements are presented. Radiation outside the atmosphere is considered with emphasis placed on global energy budget parameters, spectral and angular dependences, spatial distribution, and temporal variations of solar and thermal radiation. Radiation fluxes inside the atmosphere below 90 km are also considered with attention given to the solar flux at the surface, solar and thermal radiation fluxes from 100 km to the surface, and radiative heating and cooling below 100 km.

  17. Absorption of solar radiation in broken clouds

    SciTech Connect

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B.

    1996-04-01

    It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.

  18. Ultrarelativistic electrons and solar flare gamma-radiation

    NASA Technical Reports Server (NTRS)

    Semukhin, P. E.; Kovaltsov, G. A.

    1985-01-01

    Ten solar flares with gamma radiation in excess of 10 MeV were observed. Almost all took place within a heliolatitude greater than 60 deg, close to the solar limb, an indication of the essential anisotropy of high-energy gamma radiation. This high-energy solar flare gamma radiation can be explained by the specific features of the bremsstrahlung of ultrarelativistic electrons trapped within the magnetic arc of the solar atmosphere, even if the acceleration of the electrons is anisotropic.

  19. NREL Solar Radiation Resource Assessment Project: Status and outlook. FY 1991 annual progress report

    SciTech Connect

    Renne, D.; Riordan, C.; Maxwell, E.; Stoffel, T.; Marion, B.; Rymes, M.; Wilcox, S.; Myers, D.

    1992-05-01

    This report summarizes the activities and accomplishments of NREL`s Solar Radiation Resource Assessment Project during fiscal year 1991. Currently, the primary focus of the SRRAP is to produce a 1961--1990 National Solar Radiation Data Base, providing hourly values of global horizontal, diffuse, and direct normal solar radiation at approximately 250 sites around the United States. Because these solar radiation quantities have been measured intermittently at only about 50 of these sites, models were developed and applied to the majority of the stations to provide estimates of these parameters. Although approximately 93% of the data base consists of modeled data this represents a significant improvement over the SOLMET/ERSATZ 1952--1975 data base. The magnitude and importance of this activity are such that the majority of SRRAP human and financial in many other activities, which are reported here. These include the continued maintenance of a solar radiation monitoring network in the southeast United States at six Historically Black Colleges and Universities (HBCU`s), the transfer of solar radiation resource assessment technology through a variety of activities, participation in international programs, and the maintenance and operation of NREL`s Solar Radiation Research Laboratory. 17 refs.

  20. Solar radiation on a catenary collector

    NASA Technical Reports Server (NTRS)

    Crutchik, M.; Appelbaum, J.

    1992-01-01

    A tent-shaped structure with a flexible photovoltaic blanket acting as a catenary collector is presented. The shadow cast by one side of the collector produces a shadow on the other side of the collector. This self-shading effect is analyzed. The direct beam, the diffuse, and the albedo radiation on the collector are determined. An example is given for the insolation on the collector operating on Viking Lander 1 (VL1).

  1. Solar radiation on a catenary collector

    NASA Technical Reports Server (NTRS)

    Crutchik, M.; Appelbaum, J.

    1992-01-01

    A tent-shaped structure with a flexible photovoltaic blanket acting as a catenary collector is presented. The shadow cast by one side of the collector on the other side producing a self shading effect is analyzed. The direct beam, the diffuse and the albedo radiation on the collector are determined. An example is given for the insolation on the collector operating on the martian surface for the location of Viking Lander 1 (VL1).

  2. SUMER: Solar Ultraviolet Measurements of Emitted Radiation

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch, E.; Poland, A. I.

    1988-01-01

    The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

  3. SUMER: Solar Ultraviolet Measurements of Emitted Radiation

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.; Lemaire, P.; Marsch, E.

    1992-01-01

    The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of Extreme Ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy, provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature from 10,000 to more than 1,800,000 K.

  4. Polyethylene bags and solar ultraviolet radiation

    SciTech Connect

    Holm-Hansen, O.; Helbling, E.W. )

    1993-01-22

    This technical comment questions the use of polyethylene bags to collect and store samples in a previously reported study on the effects of solar ultraviolet radiation on natural phytoplankton assemblages in Antarctic waters. A significant difference in the photosynthetic rates was noted for samples in glassware as opposed to bags, although the overall conclusions remained similar. A response by the original authors is included. 1 tab.

  5. On-Orbit Performance of MODIS Solar Diffuser Stability Monitor

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Angal, Amit; Choi, Taeyoung; Sun, Jungiang; Johnson, Eric

    2014-01-01

    MODIS reflective solar bands (RSB) calibration is provided by an on-board solar diffuser (SD). On-orbit changes in the SD bi-directional reflectance factor (BRF) are tracked by a solar diffuser stability monitor (SDSM). The SDSM consists of a solar integration sphere (SIS) with nine detectors covering wavelengths from 0.41 to 0.94 microns. It functions as a ratioing radiometer, making alternate observations of the sunlight through a fixed attenuation screen and the sunlight diffusely reflected from the SD during each scheduled SD/SDSM calibration event. Since launch, Terra and Aqua MODIS SD/SDSM systems have been operated regularly to support the RSB on-orbit calibration. This paper provides an overview of MODIS SDSM design functions, its operation and calibration strategies, and on-orbit performance. Changes in SDSM detector responses over time and their potential impact on tracking SD on-orbit degradation are examined. Also presented in this paper are lessons learned from MODIS SD/SDSM calibration system and improvements made to the VIIRS SD/SDSM system, including preliminary comparisons of MODIS and VIIRS SDSM on-orbit performance.

  6. ESTIMATING SOLAR RADIATION EXPOSURE IN WETLANDS USING RADIATION MODELS, FIELD DATA, AND GEOGRAPHIC INFORMATION SYSTEMS

    EPA Science Inventory

    This seminar will describe development of methods for the estimation of solar radiation doses in wetlands. The methodology presents a novel approach to incorporating aspects of solar radiation dosimetry that have historically received limited attention. These include effects of a...

  7. High mortality of Red Sea zooplankton under ambient solar radiation.

    PubMed

    Al-Aidaroos, Ali M; El-Sherbiny, Mohsen M O; Satheesh, Sathianeson; Mantha, Gopikrishna; Agustī, Susana; Carreja, Beatriz; Duarte, Carlos M

    2014-01-01

    High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiation doses with zooplankton mortality were evaluated by exposing organisms, enclosed in quartz bottles, allowing all the wavelengths of solar radiation to penetrate, to five different levels of ambient solar radiation (100%, 21.6%, 7.2%, 3.2% and 0% of solar radiation). The maximum mortality rates under ambient solar radiation levels averaged (±standard error of the mean, SEM) 18.4±5.8% h(-1), five-fold greater than the average mortality in the dark for the eight taxa tested. The UV-B radiation required for mortality rates to reach ½ of maximum values averaged (±SEM) 12±5.6 h(-1)% of incident UVB radiation, equivalent to the UV-B dose at 19.2±2.7 m depth in open coastal Red Sea waters. These results confirm that Red Sea zooplankton are highly vulnerable to ambient solar radiation, as a consequence of the combination of high incident radiation and high water transparency allowing deep penetration of damaging UV-B radiation. These results provide evidence of the significance of ambient solar radiation levels as a stressor of marine zooplankton communities in tropical, oligotrophic waters. Because the oligotrophic ocean extends across 70% of the ocean surface, solar radiation can be a globally-significant stressor for the ocean ecosystem, by constraining zooplankton use of the upper levels of the water column and, therefore, the efficiency of food transfer up the food web in the oligotrophic ocean. PMID:25309996

  8. High mortality of Red Sea zooplankton under ambient solar radiation.

    PubMed

    Al-Aidaroos, Ali M; El-Sherbiny, Mohsen M O; Satheesh, Sathianeson; Mantha, Gopikrishna; Agustī, Susana; Carreja, Beatriz; Duarte, Carlos M

    2014-01-01

    High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiation doses with zooplankton mortality were evaluated by exposing organisms, enclosed in quartz bottles, allowing all the wavelengths of solar radiation to penetrate, to five different levels of ambient solar radiation (100%, 21.6%, 7.2%, 3.2% and 0% of solar radiation). The maximum mortality rates under ambient solar radiation levels averaged (±standard error of the mean, SEM) 18.4±5.8% h(-1), five-fold greater than the average mortality in the dark for the eight taxa tested. The UV-B radiation required for mortality rates to reach ½ of maximum values averaged (±SEM) 12±5.6 h(-1)% of incident UVB radiation, equivalent to the UV-B dose at 19.2±2.7 m depth in open coastal Red Sea waters. These results confirm that Red Sea zooplankton are highly vulnerable to ambient solar radiation, as a consequence of the combination of high incident radiation and high water transparency allowing deep penetration of damaging UV-B radiation. These results provide evidence of the significance of ambient solar radiation levels as a stressor of marine zooplankton communities in tropical, oligotrophic waters. Because the oligotrophic ocean extends across 70% of the ocean surface, solar radiation can be a globally-significant stressor for the ocean ecosystem, by constraining zooplankton use of the upper levels of the water column and, therefore, the efficiency of food transfer up the food web in the oligotrophic ocean.

  9. Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols

    NASA Astrophysics Data System (ADS)

    Kalidindi, Sirisha; Bala, Govindasamy; Modak, Angshuman; Caldeira, Ken

    2015-05-01

    The climatic effects of Solar Radiation Management (SRM) geoengineering have been often modeled by simply reducing the solar constant. This is most likely valid only for space sunshades and not for atmosphere and surface based SRM methods. In this study, a global climate model is used to evaluate the differences in the climate response to SRM by uniform solar constant reduction and stratospheric aerosols. Our analysis shows that when global mean warming from a doubling of CO2 is nearly cancelled by both these methods, they are similar when important surface and tropospheric climate variables are considered. However, a difference of 1 K in the global mean stratospheric (61-9.8 hPa) temperature is simulated between the two SRM methods. Further, while the global mean surface diffuse radiation increases by ~23 % and direct radiation decreases by about 9 % in the case of sulphate aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (~1.0 %) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2 % decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (~8 %) and net primary productivity (~3 %). Based on our results we conclude that the climate states produced by a reduction in solar constant and addition of aerosols into the stratosphere can be considered almost similar except for two important aspects: stratospheric temperature change and the consequent implications for the dynamics and the chemistry of the stratosphere and the partitioning of direct versus diffuse radiation reaching the surface. Further, the likely dependence of global hydrological cycle response on aerosol particle size and the latitudinal and

  10. Three-temperature plasma shock solutions with gray radiation diffusion

    NASA Astrophysics Data System (ADS)

    Johnson, B. M.; Klein, R. I.

    2016-04-01

    The effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron-ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  11. Three-temperature plasma shock solutions with gray radiation diffusion

    DOE PAGESBeta

    Johnson, Bryan M.; Klein, Richard I.

    2016-04-19

    Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation.more » Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.« less

  12. Improvements of VIIRS and MODIS Solar Diffuser and Lunar Calibration

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Butler, James J.; Lei, Ning; Sun, Junqiang; Fulbright, Jon; Wang, Zhipeng; McIntire, Jeff; Angal, Amit Avinash

    2013-01-01

    Both VIIRS and MODIS instruments use solar diffuser (SD) and lunar observations to calibrate their reflective solar bands (RSB). A solar diffuser stability monitor (SDSM) is used to track the SD on-orbit degradation. On-orbit observations have shown similar wavelength-dependent SD degradation (larger at shorter VIS wavelengths) and SDSM detector response degradation (larger at longer NIR wavelengths) for both VIIRS and MODIS instruments. In general, the MODIS scan mirror has experienced more degradation in the VIS spectral region whereas the VIIRS rotating telescope assembly (RTA) mirrors have seen more degradation in the NIR and SWIR spectral region. Because of this wavelength dependent mirror degradation, the sensor's relative spectral response (RSR) needs to be modulated. Due to differences between the solar and lunar spectral irradiance, the modulated RSR could have different effects on the SD and lunar calibration. In this paper, we identify various factors that should be considered for the improvements of VIIRS and MODIS solar and lunar calibration and examine their potential impact. Specifically, we will characterize and assess the calibration impact due to SD and SDSM attenuation screen transmission (uncertainty), SD BRF uncertainty and onorbit degradation, SDSM detector response degradation, and modulated RSR resulting from the sensor's optics degradation. Also illustrated and discussed in this paper are the calibration strategies implemented in the VIIRS and MODIS SD and lunar calibrations and efforts that could be made for future improvements.

  13. Radiation Belts Throughout the Solar System

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.

    2008-12-01

    The several preceding decades of deep space missions have demonstrated that the generation of planetary radiation belts is a universal phenomenon. All strongly magnetized planets show well developed radiation regions, specifically Earth, Jupiter, Saturn, Uranus, and Neptune. The similarities occur despite the tremendous differences between the planets in size, levels of magnetization, external environments, and most importantly, in the fundamental processes that power them. Some planets like Jupiter are powered overwhelmingly by planetary rotation, much like astrophysical pulsars, whereas others, like Earth and probably Uranus, are powered externally by the interplanetary environment. Uranus is a particularly interesting case in that despite the peculiarities engendered by its ecliptic equatorial spin axis orientation, its magnetosphere shows dynamical behavior similar to that of Earth as well as radiation belt populations and associated wave emissions that are perhaps more intense than expected based on Earth-derived theories. Here I review the similarities and differences between the radiation regions of radiation belts throughout the solar system. I discuss the value of the comparative approach to radiation belt physics as one that allows critical factors to be evaluated in environments that are divorced from the special complex conditions that prevail in any one environment, such as those at Earth.

  14. Is there a transition of solar radiation from dimming to brightening over India?

    NASA Astrophysics Data System (ADS)

    Soni, V. K.; Pandithurai, G.; Pai, D. S.

    2016-03-01

    Recent observational studies show that solar radiation incident on ground has not been stable over the last several decades but underwent significant multi-decadal variations. From the 1950s, solar radiation has had a general decreasing trend, named dimming. Since the late 1980s, a trend reversal and partial recovery has been observed at many observations sites across the globe; it is the so-called brightening. The present study examined temporal and spatial trends in surface solar radiation (global and diffuse) and sunshine duration in India using a 40-year data set (1971-2010) of the twelve stations of solar radiation network of the India Meteorological Department. The research work examines the global solar radiation trends in all-sky and cloud-free sky conditions. The long-term variability in the diffuse components of solar radiation, bright sunshine duration, and cloud cover has also been studied over India. India is one of the few regions that showed a continuous and steady decline in global solar radiation from the 1970s to 2000. The declining trend of all-sky global irradiance over India as a whole was 0.6 Wm- 2 year- 1 during 1971-2000 and 0.2 Wm- 2 year - 1 during 2001-2010. A third-order polynomial fit to the data indicated a reversal in all-sky global irradiance around 2001 at some sites. Reversal or stabilization of global irradiance is also seen in seasonal mean values at some of the stations. The reversal in clear-sky global irradiance was clearly evident from 2001. Similar trend is also observed in bright sunshine duration. This confirms the well-known phenomenon of global dimming and global brightening over India. The analysis of global irradiance data highlights the fact that in general the dimming/brightening is station dependent because of regional sources and meteorology which contribute to the variation in solar irradiance.

  15. Theoretical and Numerical Investigation of Radiative Extinction of Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ray, Anjan

    1996-01-01

    The influence of soot radiation on diffusion flames was investigated using both analytical and numerical techniques. Soot generated in diffusion flames dominate the flame radiation over gaseous combustion products and can significantly lower the temperature of the flame. In low gravity situations there can be significant accumulation of soot and combustion products in the vicinity of the primary reaction zone owing to the absence of any convective buoyant flow. Such situations may result in substantial suppression of chemical activities in a flame, and the possibility of a radiative extinction may also be anticipated. The purpose of this work was to not only investigate the possibility of radiative extinction of a diffusion flame but also to qualitatively and quantitatively analyze the influence of soot radiation on a diffusion flame. In this study, first a hypothetical radiative loss profile of the form of a sech(sup 2) was assumed to influence a pure diffusion flame. It was observed that the reaction zone can, under certain circumstances, move through the radiative loss zone and locate itself on the fuel side of the loss zone contrary to our initial postulate. On increasing the intensity and/or width of the loss zone it was possible to extinguish the flame, and extinction plots were generated. In the presence of a convective flow, however, the movement of the temperature and reaction rate peaks indicated that the flame behavior is more complicated compared to a pure diffusional flame. A comprehensive model of soot formation, oxidation and radiation was used in a more involved analysis. The soot model of Syed, Stewart and Moss was used for soot nucleation and growth and the model of Nagle and Strickland-Constable was used for soot oxidation. The soot radiation was considered in the optically thin limit. An analysis of the flame structure revealed that the radiative loss term is countered both by the reaction term and the diffusion term. The essential balance for

  16. Stability of Stationary Solutions of the Multifrequency Radiation Diffusion Equations

    SciTech Connect

    Hald, O H; Shestakov, A I

    2004-01-20

    A nondimensional model of the multifrequency radiation diffusion equation is derived. A single material, ideal gas, equation of state is assumed. Opacities are proportional to the inverse of the cube of the frequency. Inclusion of stimulated emission implies a Wien spectrum for the radiation source function. It is shown that the solutions are uniformly bounded in time and that stationary solutions are stable. The spatially independent solutions are asymptotically stable, while the spatially dependent solutions of the linearized equations approach zero.

  17. Diffuse Radiation from the Aquila Rift

    NASA Astrophysics Data System (ADS)

    Jyothy, S. N.; Murthy, Jayant; Karuppath, Narayanankutty; Sujatha, N. V.

    2015-12-01

    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm-2 s-1 sr-1 Å-1 with no correlation with either the Galactic latitude or the 100 μm infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6-0.7 in the UV with a phase function asymmetry factor (g) of 0.2-0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

  18. A model for inactivation of microbes suspended in the atmosphere by solar ultraviolet radiation.

    PubMed

    Ben-David, Avishai; Sagripanti, Jose-Luis

    2010-01-01

    Solar ultraviolet (UV) light within 280-320 nm (UVB) is the primary cause for virus inactivation in the atmosphere. Only the effect of the direct component has been previously evaluated. We developed a simple regression model to estimate the inactivation of a virus due to direct (unscattered), diffuse (scattered) and total (direct + diffuse) components of solar UV (daily integrated irradiances). The model predicts the maximum number of radiation-days a virus will survive at a given altitude above the ground in rural and urban environments under clear skies. We explored the effect of several environmental variables: visibility, altitude and ground reflectivity. We found that the effect of diffuse radiation on virus inactivation was larger than the direct component. The diffuse irradiance increased with ground albedo (mainly due to reflection of the direct attenuated solar off the ground) and decreased with increased visibility (proportional to aerosol loading in the atmosphere). The diffuse component increased with altitude, but the ratio of diffuse to the total decreased with increased altitude, highlighting the importance of the diffuse component of UV near the ground. Our model may help public health studies in predicting and understanding the effect of environmental parameters on the survival of germs.

  19. Radiative Extinction of Gaseous Spherical Diffusion Flames in Microgravity

    NASA Technical Reports Server (NTRS)

    Santa, K. J.; Chao, B. H.; Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Axelbaum, R. L.

    2007-01-01

    Radiative extinction of spherical diffusion flames was investigated experimentally and numerically. The experiments involved microgravity spherical diffusion flames burning ethylene and propane at 0.98 bar. Both normal (fuel flowing into oxidizer) and inverse (oxidizer flowing into fuel) flames were studied, with nitrogen supplied to either the fuel or the oxygen. Flame conditions were chosen to ensure that the flames extinguished within the 2.2 s of available test time; thus extinction occurred during unsteady flame conditions. Diagnostics included color video and thin-filament pyrometry. The computations, which simulated flow from a porous sphere into a quiescent environment, included detailed chemistry, transport and radiation, and yielded transient results. Radiative extinction was observed experimentally and simulated numerically. Extinction time, peak temperature, and radiative loss fraction were found to be independent of flow rate except at very low flow rates. Radiative heat loss was dominated by the combustion products downstream of the flame and was found to scale with flame surface area, not volume. For large transient flames the heat release rate also scaled with surface area and thus the radiative loss fraction was largely independent of flow rate. Peak temperatures at extinction onset were about 1100 K, which is significantly lower than for kinetic extinction. One observation of this work is that while radiative heat losses can drive transient extinction, this is not because radiative losses are increasing with time (flame size) but rather because the heat release rate is falling off as the temperature drops.

  20. [Research on clouds affecting the spectra of solar ultraviolet radiation].

    PubMed

    Zhao, Xiao-Yan; Yan, Hai-Tao; Zhen, Zhi-Qiang; Tang, Zheng-Xin; Wang, Hui

    2011-01-01

    In the present paper, using UV CCD optical multi-channel analyzer, the solar ultraviolet radiation spectra under the conditions of cloud cover were measured, and the impact of clouds on the solar ultraviolet radiation spectra were studied mostly. The results of spectral analysis showed that the intensity of solar ultraviolet radiation spectra was weakened by the clouds. The solar ultraviolet radiation spectral intensity attenuation depended on the wavelength and decreased with decreasing wavelength. The greater the cloud cover, the stronger the attenuation, The solar ultraviolet radiation spectral intensity at wavelengths below 315 nm was affected relatively less by the cloud cover. These results have more important practical applications. When we use solar ultraviolet radiation spectrum to study the atmospheric composition, we should choose the spectral band that is less affected by the atmospheric environment.

  1. Attenuation coefficient of usable solar radiation of the global oceans

    NASA Astrophysics Data System (ADS)

    Lin, Junfang; Lee, Zhongping; Ondrusek, Michael; Kahru, Mati

    2016-05-01

    Usable solar radiation (USR) represents spectrally integrated solar energy in the spectral range of 400-560 nm, a domain where photons penetrate the most in oceanic waters and thus contribute to photosynthesis and heating at deeper depths. Through purely numerical simulations, it was found that the diffuse attenuation coefficient of downwelling USR (Kd(USR), m-1) is nearly a constant vertically in the upper water column for clear waters and most turbid waters. Subsequently an empirical model was developed to estimate Kd(USR) based on the diffuse attenuation coefficient at 490 nm (Kd(490), m-1). We here evaluate this relationship using data collected from a wide range of oceanic and coastal environments and found that the relationship between Kd(490) and Kd(USR) developed via the numerical simulation is quite robust. We further refined this relationship to extend the applicability to "clearest" natural waters. This refined relationship was then used to produce sample distribution of Kd(USR) of global oceans. As expected, extremely low Kd(USR) (˜0.02 m-1) was observed in ocean gyres, while significantly higher Kd(USR) (˜5.2 m-1) was found in very turbid coastal regions. A useful application of Kd(USR) is to easily and accurately propagate surface USR to deeper depths, potentially to significantly improve the estimation of basin scale primary production and heat fluxes in the upper water column.

  2. A rapid radiative transfer model for reflection of solar radiation

    NASA Technical Reports Server (NTRS)

    Xiang, X.; Smith, E. A.; Justus, C. G.

    1994-01-01

    A rapid analytical radiative transfer model for reflection of solar radiation in plane-parallel atmospheres is developed based on the Sobolev approach and the delta function transformation technique. A distinct advantage of this model over alternative two-stream solutions is that in addition to yielding the irradiance components, which turn out to be mathematically equivalent to the delta-Eddington approximation, the radiance field can also be expanded in a mathematically consistent fashion. Tests with the model against a more precise multistream discrete ordinate model over a wide range of input parameters demonstrate that the new approximate method typically produces average radiance differences of less than 5%, with worst average differences of approximately 10%-15%. By the same token, the computational speed of the new model is some tens to thousands times faster than that of the more precise model when its stream resolution is set to generate precise calculations.

  3. A Rapid Radiative Transfer Model for Reflection of Solar Radiation.

    NASA Astrophysics Data System (ADS)

    Xiang, X.; Smith, E. A.; Justus, C. G.

    1994-07-01

    A rapid analytical radiative transfer model for reflection of solar radiation in plane-parallel atmospheres is developed based on the Sobolev approach and the delta function transformation technique. A distinct advantage of this model over alternative two-stream solutions is that in addition to yielding the irradiance components, which turn out to be mathematically equivalent to the delta-Eddington approximation, the radiance field can also be expanded in a mathematically consistent fashion. Tests with the model against a more precise multistream discrete ordinate model over a wide range of input parameters demonstrate that the new approximate method typically produces average radiance differences of less than 5%, with worst average differences of 10%-15%. By the same token, the computational speed of the new model is some tens to thousands times faster than that of the more precise model when its stream resolution is set to generate precise calculations.

  4. Implicit solution of large-scale radiation diffusion problems

    SciTech Connect

    Brown, P N; Graziani, F; Otero, I; Woodward, C S

    2001-01-04

    In this paper, we present an efficient solution approach for fully implicit, large-scale, nonlinear radiation diffusion problems. The fully implicit approach is compared to a semi-implicit solution method. Accuracy and efficiency are shown to be better for the fully implicit method on both one- and three-dimensional problems with tabular opacities taken from the LEOS opacity library.

  5. Ground truth data for test sites (SL-3). [solar radiation and thermal radiation brightness temperature measurements

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Field measurements performed simultaneously with Skylab overpasses in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. The solar radiation region from 400 to 1300 nanometers and the thermal radiation region from 8 to 14 micrometer region were investigated. The measurements of direct solar radiation were analyzed for atmospheric optical depth; the total and reflected solar radiation were analyzed for target reflectivity. These analyses were used in conjunction with a radiative transfer computer program in order to calculate the amount and spectral distribution of solar radiation at the apertures of the EREP sensors. The instrumentation and techniques employed, calibrations and analyses performed, and results obtained are discussed.

  6. The diffuse component of the cosmic X-radiation

    NASA Technical Reports Server (NTRS)

    Boldt, E. A.; Garmire, C.

    1978-01-01

    The A-2 experiment on HEAO-1 is specifically developed to study the diffuse radiation of the entire X-ray sky over a wide bandwidth, covering both the soft X-ray emission from nearby regions of the galaxy and the isotropic hard X-radiation indicative of remote extragalactic origins. A partial conclusion from the experiment is that a hot thermal plasma, on a scale comparable to that of the universe, may be the principal source of hard X-radiation characteristic of the extragalactic sky. Some key features of this background were defined.

  7. Plant response to solar ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Caldwell, M. M.

    1981-01-01

    Plant reactions and mechanisms of reaction to solar UV radiation are reviewed, along with characteristics of plants which enhance UV tolerance. Wavelength regions to which proteins are particularly sensitive are examined and the possibility of synergistic effects from photoreactions to multiple wavelengths is considered, along with available evidence of nonadditive plant spectral responses to UV radiation. Decreases in atmospheric ozone content are explored in terms of UV wavelengths which would increase with the ozone decreases, particularly for UV-B, which depresses photosynthesis and would increase 1% with a 16% reduction of stratospheric ozone. Higher elevations are projected to display effects of increased UV incident flux first, and global distributions of UV increases due to atmospheric inhomogeneity and water surface clarity are examined. Finally, the response of plant nucleic acids, DNA, chlorophyll to enhanced UV are described, along with repair, avoidance, and optical mechanisms which aid plant survival

  8. Comparison of the Radiative Two-Flux and Diffusion Approximations

    NASA Technical Reports Server (NTRS)

    Spuckler, Charles M.

    2006-01-01

    Approximate solutions are sometimes used to determine the heat transfer and temperatures in a semitransparent material in which conduction and thermal radiation are acting. A comparison of the Milne-Eddington two-flux approximation and the diffusion approximation for combined conduction and radiation heat transfer in a ceramic material was preformed to determine the accuracy of the diffusion solution. A plane gray semitransparent layer without a substrate and a non-gray semitransparent plane layer on an opaque substrate were considered. For the plane gray layer the material is semitransparent for all wavelengths and the scattering and absorption coefficients do not vary with wavelength. For the non-gray plane layer the material is semitransparent with constant absorption and scattering coefficients up to a specified wavelength. At higher wavelengths the non-gray plane layer is assumed to be opaque. The layers are heated on one side and cooled on the other by diffuse radiation and convection. The scattering and absorption coefficients were varied. The error in the diffusion approximation compared to the Milne-Eddington two flux approximation was obtained as a function of scattering coefficient and absorption coefficient. The percent difference in interface temperatures and heat flux through the layer obtained using the Milne-Eddington two-flux and diffusion approximations are presented as a function of scattering coefficient and absorption coefficient. The largest errors occur for high scattering and low absorption except for the back surface temperature of the plane gray layer where the error is also larger at low scattering and low absorption. It is shown that the accuracy of the diffusion approximation can be improved for some scattering and absorption conditions if a reflectance obtained from a Kubelka-Munk type two flux theory is used instead of a reflection obtained from the Fresnel equation. The Kubelka-Munk reflectance accounts for surface reflection and

  9. Simulation of solar radiative transfer in cumulus clouds

    SciTech Connect

    Zuev, V.E.; Titov, G.A.

    1996-04-01

    This work presents a 3-D model of radiative transfer which is used to study the relationship between the spatial distribution of cumulus clouds and fluxes (albedo and transmittance) of visible solar radiation.

  10. Diffusion tensor imaging of the optic radiations after optic neuritis.

    PubMed

    Kolbe, Scott; Bajraszewski, Clare; Chapman, Caron; Nguyen, Tan; Mitchell, Peter; Paine, Mark; Butzkueven, Helmut; Johnston, Leigh; Kilpatrick, Trevor; Egan, Gary

    2012-09-01

    Trans-synaptic degeneration could exacerbate neurodegeneration in multiple sclerosis (MS). We aimed to assess whether anterograde trans-synaptic degeneration could be identified in the primary visual pathway in vivo. Diffusion tensor imaging (DTI) was used to assess the optic radiations in 15 patients with previous optic nerve inflammation and 9 healthy volunteers. A probabilistic atlas of the optic radiations was created from healthy diffusion tractography data. Lengthwise profiles for DTI parameters (axial [λ(||) ], radial [λ(⟂) ] and mean diffusivity [MD], fractional anisotropy [FA] and the angle of deviation of the principal eigenvector [α]) were analyzed for patients and controls. Patients also underwent multifocal visual evoked potential (mfVEP) assessments to characterize the latency and amplitude of cortical potentials. Correlations were performed between mfVEP latency and amplitude in the left and right visual hemi-fields and DTI parameters in the contra-lateral optic radiations. Patients displayed a significant decrease in λ(||) within the body of both optic radiations, which significantly correlated with loss of mfVEP amplitude. Abnormal λ(⟂) and FA were detected bilaterally throughout the optic radiations in patients but the abnormality was not associated with amplitude reduction or latency prolongation of the mfVEP. An abnormal α value was observed in the left optic radiations of patients, and the α value in the body of the optic radiations also correlated with mfVEP amplitude loss. The assocation between bilateral DTI abnormalities within the optic radiations and loss of afferent electrical activity could indicate anterograde trans-synaptic degeneration occurs following optic neuritis.

  11. Using a simple apparatus to measure direct and diffuse photosynthetically active radiation at remote locations.

    PubMed

    Cruse, Michael J; Kucharik, Christopher J; Norman, John M

    2015-01-01

    Plant canopy interception of photosynthetically active radiation (PAR) drives carbon dioxide (CO2), water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM) Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal) of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the potential to support

  12. Using a Simple Apparatus to Measure Direct and Diffuse Photosynthetically Active Radiation at Remote Locations

    PubMed Central

    Cruse, Michael J.; Kucharik, Christopher J.; Norman, John M.

    2015-01-01

    Plant canopy interception of photosynthetically active radiation (PAR) drives carbon dioxide (CO2), water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM) Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal) of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the potential to support

  13. 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.

  14. Biological sensors for solar ultraviolet radiation.

    PubMed

    Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Menck, Carlos F M; Schuch, André P

    2011-01-01

    Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products.

  15. Biological sensors for solar ultraviolet radiation.

    PubMed

    Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Menck, Carlos F M; Schuch, André P

    2011-01-01

    Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products. PMID:22163847

  16. Outdoor Exposure to Solar Ultraviolet Radiation and Legislation in Brazil.

    PubMed

    Silva, Abel A

    2016-06-01

    The total ozone column of 265 ± 11 Dobson Units in the tropical-equatorial zones and 283 ± 16 Dobson Units in the subtropics of Brazil are among the lowest on Earth, and as a result, the prevalence of skin cancer due to solar ultraviolet radiation is among the highest. Daily erythemal doses in Brazil can be over 7,500 J m. Erythemal dose rates on cloudless days of winter and summer are typically about 0.147 W m and 0.332 W m, respectively. However, radiation enhancement events yielded by clouds have been reported with erythemal dose rates of 0.486 W m. Daily doses of the diffuse component of erythemal radiation have been determined with values of 5,053 J m and diffuse erythemal dose rates of 0.312 W m. Unfortunately, Brazilians still behave in ways that lead to overexposure to the sun. The annual personal ultraviolet radiation ambient dose among Brazilian youths can be about 5.3%. Skin cancer in Brazil is prevalent, with annual rates of 31.6% (non-melanoma) and 1.0% (melanoma). Governmental and non-governmental initiatives have been taken to increase public awareness of photoprotection behaviors. Resolution #56 by the Agência Nacional de Vigilância Sanitária has banned tanning devices in Brazil. In addition, Projects of Law (PL), like PL 3730/2004, propose that the Sistema Único de Saúde should distribute sunscreen to members of the public, while PL 4027/2012 proposes that employers should provide outdoor workers with sunscreen during professional outdoor activities. Similar laws have already been passed in some municipalities. These are presented and discussed in this study.

  17. Outdoor Exposure to Solar Ultraviolet Radiation and Legislation in Brazil.

    PubMed

    Silva, Abel A

    2016-06-01

    The total ozone column of 265 ± 11 Dobson Units in the tropical-equatorial zones and 283 ± 16 Dobson Units in the subtropics of Brazil are among the lowest on Earth, and as a result, the prevalence of skin cancer due to solar ultraviolet radiation is among the highest. Daily erythemal doses in Brazil can be over 7,500 J m. Erythemal dose rates on cloudless days of winter and summer are typically about 0.147 W m and 0.332 W m, respectively. However, radiation enhancement events yielded by clouds have been reported with erythemal dose rates of 0.486 W m. Daily doses of the diffuse component of erythemal radiation have been determined with values of 5,053 J m and diffuse erythemal dose rates of 0.312 W m. Unfortunately, Brazilians still behave in ways that lead to overexposure to the sun. The annual personal ultraviolet radiation ambient dose among Brazilian youths can be about 5.3%. Skin cancer in Brazil is prevalent, with annual rates of 31.6% (non-melanoma) and 1.0% (melanoma). Governmental and non-governmental initiatives have been taken to increase public awareness of photoprotection behaviors. Resolution #56 by the Agência Nacional de Vigilância Sanitária has banned tanning devices in Brazil. In addition, Projects of Law (PL), like PL 3730/2004, propose that the Sistema Único de Saúde should distribute sunscreen to members of the public, while PL 4027/2012 proposes that employers should provide outdoor workers with sunscreen during professional outdoor activities. Similar laws have already been passed in some municipalities. These are presented and discussed in this study. PMID:27115230

  18. Glass diffusion source for constraining BSF region of a solar cell

    DOEpatents

    Lesk, I.A.; Pryor, R.A.; Coleman, M.G.

    1982-08-27

    The present invention is directed to a method of fabricating a solar cell comprising simultaneous diffusion of the p and n dopant materials into the solar cell substrate. The simultaneous diffusion process is preceded by deposition of a capping layer impervious to doping by thermal diffusion processes.

  19. SUB-THz RADIATION MECHANISMS IN SOLAR FLARES

    SciTech Connect

    Fleishman, Gregory D.; Kontar, Eduard P.

    2010-02-01

    Observations in the sub-THz range of large solar flares have revealed a mysterious spectral component increasing with frequency and hence distinct from the microwave component commonly accepted to be produced by gyrosynchrotron (GS) emission from accelerated electrons. Evidently, having a distinct sub-THz component requires either a distinct emission mechanism (compared to the GS one), or different properties of electrons and location, or both. We find, however, that the list of possible emission mechanisms is incomplete. This Letter proposes a more complete list of emission mechanisms, capable of producing a sub-THz component, both well known and new in this context, and calculates a representative set of their spectra produced by (1) free-free emission, (2) GS emission, (3) synchrotron emission from relativistic positrons/electrons, (4) diffusive radiation, and (5) Cherenkov emission. We discuss the possible role of the mechanisms in forming the sub-THz emission and emphasize their diagnostics potential for flares.

  20. Stratospheric Aerosols for Solar Radiation Management

    NASA Astrophysics Data System (ADS)

    Kravitz, Ben

    SRM in the context of this entry involves placing a large amount of aerosols in the stratosphere to reduce the amount of solar radiation reaching the surface, thereby cooling the surface and counteracting some of the warming from anthropogenic greenhouse gases. The way this is accomplished depends on the specific aerosol used, but the basic mechanism involves backscattering and absorbing certain amounts of solar radiation aloft. Since warming from greenhouse gases is due to longwave (thermal) emission, compensating for this warming by reduction of shortwave (solar) energy is inherently imperfect, meaning SRM will have climate effects that are different from the effects of climate change. This will likely manifest in the form of regional inequalities, in that, similarly to climate change, some regions will benefit from SRM, while some will be adversely affected, viewed both in the context of present climate and a climate with high CO2 concentrations. These effects are highly dependent upon the means of SRM, including the type of aerosol to be used, the particle size and other microphysical concerns, and the methods by which the aerosol is placed in the stratosphere. SRM has never been performed, nor has deployment been tested, so the research up to this point has serious gaps. The amount of aerosols required is large enough that SRM would require a major engineering endeavor, although SRM is potentially cheap enough that it could be conducted unilaterally. Methods of governance must be in place before deployment is attempted, should deployment even be desired. Research in public policy, ethics, and economics, as well as many other disciplines, will be essential to the decision-making process. SRM is only a palliative treatment for climate change, and it is best viewed as part of a portfolio of responses, including mitigation, adaptation, and possibly CDR. At most, SRM is insurance against dangerous consequences that are directly due to increased surface air

  1. Radiation from Gas-Jet Diffusion Flames in Microgravity Environments

    NASA Technical Reports Server (NTRS)

    Bahadori, M. Yousef; Edelman, Raymond B.; Sotos, Raymond G.; Stocker, Dennis P.

    1991-01-01

    This paper presents the first demonstration of quantitative flame-radiation measurement in microgravity environments, with the objective of studying the influences and characteristics of radiative transfer on the behavior of gas-jet diffusion flames with possible application to spacecraft fire detection. Laminar diffusion flames of propane, burning in quiescent air at atmospheric pressure, are studied in the 5.18-Second Zero-Gravity Facility of NASA Lewis Research Center. Radiation from these flames is measured using a wide-view angle, thermopile-detector radiometer, and comparisons are made with normal-gravity flames. The results show that the radiation level is significantly higher in microgravity compared to normal-gravity environments due to larger flame size, enhanced soot formation, and entrapment of combustion products in the vicinity of the flame. These effects are the consequences of the removal of buoyancy which makes diffusion the dominant mechanism of transport. The results show that longer test times may be needed to reach steady state in microgravity environments.

  2. [Radiation diagnosis of diffuse lung diseases: Part I].

    PubMed

    Stashuk, G A; Dubrova, S E

    2005-01-01

    Based on the data on 150 patients with diffuse lung diseases, the authors present the X-ray and computed topographic semiotics of changes in lung tissue in a number of diseases from this group. The differential diagnosis of diffuse lung diseases has certain difficulties whose solution is association with the application of complex radiation studies (digital fluorography, classical X-ray study, X-ray computed tomography, and magnetic resonance imaging). These techniques not only assess the status of the parenchyma of the lung and the extent of a process, but also permit a follow-up monitoring and evaluation of the efficiency of the therapy performed.

  3. Silicon diffusion in aluminum for rear passivated solar cells

    SciTech Connect

    Urrejola, Elias; Peter, Kristian; Plagwitz, Heiko; Schubert, Gunnar

    2011-04-11

    We show that the lateral spread of silicon in a screen-printed aluminum layer increases by (1.50{+-}0.06) {mu}m/ deg. C, when increasing the peak firing temperature within an industrially applicable range. In this way, the maximum spread limit of diffused silicon in aluminum is predictable and does not depend on the contact area size but on the firing temperature. Therefore, the geometry of the rear side pattern can influence not only series resistance losses within the solar cell but the process of contact formation itself. In addition, too fast cooling lead to Kirkendall void formations instead of an eutectic layer.

  4. Solar terrestrial radiation data from the Sleepers River Research Watershed

    NASA Astrophysics Data System (ADS)

    Hardy, Janet P.

    1994-08-01

    A long-term (24-year) database of solar and terrestrial radiation, as monitored in northern Vermont, has been compiled. This extensive database is a result of cooperative efforts among many different government agencies. This report summarizes the present status of the solar and terrestrial radiation database, the instrumentation and calibration, and methods of data measurement, acquisition and analysis.

  5. Distribution of solar radiation including slope effect in South Korea

    NASA Astrophysics Data System (ADS)

    Baek, Shin Chul; Park, Jong-Hwa; Na, Sang Il; Park, Jin-Ki

    2012-10-01

    Agriculture and ecosystems are very solar radiation-sensitive making them useful for monitoring the impact on future food production. Accurate solar radiation data are necessary to evaluate major physiological reaction of crops and an impact of climate change. For most upland crops and orchard plants growing in sloping terrain, however the meteorological data are often limited. Considering the scarcity of detailed meteorological data around the country, there is a need for methods which can estimate reference solar radiation with limited data. This study describes a method to estimate monthly average daily solar radiation of considering the slope distribution. It was calculated using the 2010's meteorological data and KT method which is entered DEM and spatial interpolation data of both monthly average daily extraterrestrial radiation and monthly average daily radiation on land surface. Extracted slope from the DEM in South Korea include range between 0∘ to 77∘ and most of the land is mountainous. According to the slope, solar radiation characteristic show to have high value in spring season (April) relatively other season. Summer season interrupt to reach direct solar radiation, cause is unstable atmospheric and cloud. The distributions of monthly accumulated solar radiation indicated that differences caused by the topography effect are more important in winter than in other season because of the dependency on the solar altitude angle and duration of sunshine. Result of KT method is confirmed to overestimate monthly average 1.38MJ⁄m􀬶⁄day than solar radiation weather station measurement values. Solar radiation of slope error value will need continuous research and correction through both fields survey and topography factor.

  6. Pulsar and diffuse contributions to the observed galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1980-01-01

    With the acquisition of satellite data on the energy spectrum of galactic gamma-radiation, it is clear that such radiation has a multicomponent nature. A calculation of the pulsar gamma ray emission spectrum is used together with a statistical analysis of recent data on 328 known pulsars to make a new determination of the pulsar contribution to galactic gamma ray emission. The contributions from diffuse interstellar cosmic ray induced production mechanisms to the total emission are then reexamined. It is concluded that pulsars may account for a significant fraction of galactic gamma ray emission.

  7. VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD

    SciTech Connect

    Murthy, Jayant; Henry, Richard Conn; Holberg, Jay B.

    2012-03-01

    The two Voyager spacecraft have completed their planetary exploration mission and are now probing the outer realms of the heliosphere. The Voyager ultraviolet spectrometers continued to operate well after the Voyager 2 Neptune encounter in 1989. We present a complete database of diffuse radiation observations made by both Voyagers: a total of 1943 spectra (500-1600 A) scattered throughout the sky. These include observations of dust-scattered starlight, emission lines from the hot interstellar medium, and a number of locations where no diffuse radiation was detected, with the very low upper limit of about 25 photons cm{sup -2} s{sup -1} sr{sup -1} A{sup -1}. Many of these observations were from late in the mission when there was significantly less contribution from interplanetary emission lines and thus less contamination of the interstellar signal.

  8. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  9. Solar Radiation Estimated Through Mesoscale Atmospheric Modeling over Northeast Brazil

    NASA Astrophysics Data System (ADS)

    de Menezes Neto, Otacilio Leandro; Costa, Alexandre Araújo; Ramalho, Fernando Pinto; de Maria, Paulo Henrique Santiago

    2009-03-01

    The use of renewable energy sources, like solar, wind and biomass is rapidly increasing in recent years, with solar radiation as a particularly abundant energy source over Northeast Brazil. A proper quantitative knowledge of the incoming solar radiation is of great importance for energy planning in Brazil, serving as basis for developing future projects of photovoltaic power plants and solar energy exploitation. This work presents a methodology for mapping the incoming solar radiation at ground level for Northeast Brazil, using a mesoscale atmospheric model (Regional Atmospheric Modeling System—RAMS), calibrated and validated using data from the network of automatic surface stations from the State Foundation for Meteorology and Water Resources from Ceará (Fundação Cearense de Meteorologia e Recursos Hídricos- FUNCEME). The results showed that the model exhibits systematic errors, overestimating surface radiation, but that, after the proper statistical corrections, using a relationship between the model-predicted cloud fraction, the ground-level observed solar radiation and the incoming solar radiation estimated at the top of the atmosphere, a correlation of 0.92 with a confidence interval of 13.5 W/m2 is found for monthly data. Using this methodology, we found an estimate for annual average incoming solar radiation over Ceará of 215 W/m2 (maximum in October: 260 W/m2).

  10. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    SciTech Connect

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua E-mail: jmurthy@yahoo.com E-mail: 97tyler@cardinalmail.cua.edu

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a ''second population'' of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 μm emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such ''smaller'' grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Lyα—it could be that our ''second component'' of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  11. Characterization of MODIS Solar Diffuser On-Orbit Degradation

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Chen, H.; Wang, Z.; Sun, J.; Angal, A.

    2010-01-01

    MODIS reflective solar bands (RSB) are calibrated using a solar diffuser (SD). The SD on-orbit degradation is determined by a solar diffuser stability monitor (SDSM) at 9 wavelengths from 0.41 to 0.94 microns via alternate observations of its sunlight reflected from the SD (SD view) and direct sunlight through an attenuation screen (Sun view). For each SDSM detector, a time series of ratios of its SD view to its Sun view responses tracks on-orbit changes in the SD bidirectional reflectance factor (BRF) at its wavelength. Due to an SDSM component design error, however, there exist large ripples in its Sun view responses, which have made it extremely difficult to use the original ratio approach for accurate characterization of SD on-orbit degradation. In order to mitigate the impact due to unexpected ripples, MODIS Characterization Support Team (MCST) developed a normalization approach. It relies on the fact that all SDSM detectors (D1 to D9) experience similar ripples and assumes that the SD degradation at its D9 wavelength (0.94 micron) is extremely small and can be ignored. As mission continues, the normalization approach becomes inadequate since the accumulated SD degradation at 0.94[tm can no longer be ignored. This paper presents a new approach to further improve on-orbit characterization of SD degradation. It uses a took-up table (LUT) with parameters derived from D9 observations made over a short period. Compared to other approaches, this approach can significantly reduce the impact due to ripples and that due to accumulated SD degradation at the reference detector wavelength.

  12. Online educative activities for solar ultraviolet radiation based on measurements of cloud amount and solar exposures.

    PubMed

    Parisi, A V; Downs, N; Turner, J; Amar, A

    2016-09-01

    A set of online activities for children and the community that are based on an integrated real-time solar UV and cloud measurement system are described. These activities use the functionality of the internet to provide an educative tool for school children and the public on the influence of cloud and the angle of the sun above the horizon on the global erythemal UV or sunburning UV, the diffuse erythemal UV, the global UVA (320-400nm) and the vitamin D effective UV. Additionally, the units of UV exposure and UV irradiance are investigated, along with the meaning and calculation of the UV index (UVI). This research will help ensure that children and the general public are better informed about sun safety by improving their personal understanding of the daily and the atmospheric factors that influence solar UV radiation and the solar UV exposures of the various wavebands in the natural environment. The activities may correct common misconceptions of children and the public about UV irradiances and exposure, utilising the widespread reach of the internet to increase the public's awareness of the factors influencing UV irradiances and exposures in order to provide clear information for minimizing UV exposure, while maintaining healthy, outdoor lifestyles.

  13. Online educative activities for solar ultraviolet radiation based on measurements of cloud amount and solar exposures.

    PubMed

    Parisi, A V; Downs, N; Turner, J; Amar, A

    2016-09-01

    A set of online activities for children and the community that are based on an integrated real-time solar UV and cloud measurement system are described. These activities use the functionality of the internet to provide an educative tool for school children and the public on the influence of cloud and the angle of the sun above the horizon on the global erythemal UV or sunburning UV, the diffuse erythemal UV, the global UVA (320-400nm) and the vitamin D effective UV. Additionally, the units of UV exposure and UV irradiance are investigated, along with the meaning and calculation of the UV index (UVI). This research will help ensure that children and the general public are better informed about sun safety by improving their personal understanding of the daily and the atmospheric factors that influence solar UV radiation and the solar UV exposures of the various wavebands in the natural environment. The activities may correct common misconceptions of children and the public about UV irradiances and exposure, utilising the widespread reach of the internet to increase the public's awareness of the factors influencing UV irradiances and exposures in order to provide clear information for minimizing UV exposure, while maintaining healthy, outdoor lifestyles. PMID:27450297

  14. Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.

    PubMed

    Sun, Junqiang; Chu, Mike; Wang, Menghua

    2016-08-01

    The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this

  15. Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.

    PubMed

    Sun, Junqiang; Chu, Mike; Wang, Menghua

    2016-08-01

    The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this

  16. An Exact Solution of the Linearized Multifrequency Radiation Diffusion Equation

    SciTech Connect

    Shestakov, A

    2002-02-01

    An exact solution, based on Fourier and Laplace (FL) transforms, is developed for a linearization of the system modeling the multifrequency radiation diffusion and matter energy balance equations. The model uses an ideal gas equation of state. Opacities are proportional to the inverse of the cube of the frequency, thereby simulating free-free transitions. The solution is obtained in terms of integrals over the FL coefficients of the initial conditions and explicit sources. Results are presented for two special cases. (1) No sources, initially cold radiation field, and a localized matter energy profile. (2) Initially cold matter and radiation fields and a source of matter energy extending over finite space and time intervals.

  17. The origin of the diffuse background gamma-radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations have now provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV. There is some evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation have been observed which provide evidence for its origin in nuclear processes in the early stages of the big-band cosmology and tie in these processes with galaxy fromation theory. A crucial test of the theory may lie in future observations of the background radiation in the 100 MeV to 100 GeV energy range which may be made with large orbiting spark-chamber satellite detectors. A discussion of the theoretical interpretations of present data, their connection with baryon symmetric cosmology and galaxy formation theory, and the need for future observations are given.

  18. The origin of the diffuse background gamma radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV, and evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation were observed which provide evidence for its origin in nuclear processes in the early stages of big-bang cosmology, and connect these processes with the galaxy formation theory. A test of the theory is in future observations of the background radiation in the 100 MeK to 100 GeV energy range which are made with large orbiting spark-chamber satellite detectors. The theoretical interpretations of present data, their connection with baryon-symmetric cosmology and galaxy formation theory, and the need for future observations are discussed.

  19. Effects of solar radiation on collagen and chitosan films.

    PubMed

    Sionkowska, Alina

    2006-01-01

    Photo-aging and photo-degradation are the deleterious effect of chronic exposure to sun light of many materials made of natural polymers. The resistance of the products on the action of solar radiation is very important for material scientists. The effect of solar radiation on two natural polymers: collagen and chitosan as well as collagen/chitosan blends in the form of thin films has been studied by UV-Vis and FTIR spectroscopy. It was found that UV-Vis spectra, which characterise collagen and collagen/chitosan films, were significantly altered by solar radiation. FTIR spectra of collagen and collagen/chitosan films showed that after solar irradiation the positions of amide A and amide I bands were shifted to lower wavenumbers. There was not any significant alteration of chitosan UV-Vis and FTIR spectra after solar radiation. In the condition of the experiment chitosan films were resistant to the action of solar radiation. The effect of solar UV radiation in comparison to artificial UV radiation has been discussed.

  20. Solar irradiance computations compared with observations at the Baseline Surface Radiation Network Payerne site

    SciTech Connect

    Nowak, Daniela; Vuilleumier, Laurent; Long, Charles N.; Ohmura, Atsumu

    2008-07-18

    Radiative transfer model calculations of solar fluxes during cloud free periods often show considerable discrepancies with surface radiation observations. Many efforts have been undertaken to explain the differences between modeled and observed shortwave downward radiation (SDR). In this study, MODTRAN4v3r1TM (designed later simply as MODTRANTM) was used for model simulations and compared with high quality radiation observations of the Baseline Surface Radiation Network (BSRN) site at Payerne, Switzerland. Results are presented for cloud free shortwave downward radiation calculations. The median differences of modeled minus observed global SDR are small (< 1%) and within the instrumental error. The differences of modeled and observed direct and diffuse SDR show larger discrepancies of -1.8% and 5.2% respectively. The diffuse SDR is generally overestimated by the model and more important, the model to observation linear regression slope and zero-intercept differs significantly from their ideal values of 1 and 0. Possible reasons for the discrepancies are presented and discussed and some modifications are investigated for decreasing such differences between modeled and observed diffuse SDR. However, we could not resolve all the discrepancies. The best agreement is obtained when comparing model simulations whose 550nm aerosol optical depth input is inferred from observations using nine spectral channels, and using BSRN observations performed with a new and more precise shading disk and sun tracker system. In this case, the median bias between model simulations and observed diffuse SDR is -0.4 Wm-2 (< 1%).

  1. Solar radiation measurements from coordinated radiosonde flights during the 20th March 2015 solar eclipse

    NASA Astrophysics Data System (ADS)

    Harrison, R. Giles; Marlton, Graeme; Williams, Paul; Nicoll, Keri

    2016-04-01

    Solar radiation sensors can be carried on standard weather balloon packages and provide additional information about the atmosphere's vertical structure beyond the traditional thermodynamic measurements [1]. An interesting set of circumstances for such sensors occurs during a solar eclipse, which provides a rapidly changing solar radiation environment within the duration of a typical free balloon flight. Coordinating several launches of solar radiation measuring radiosondes brings a good likelihood of at least one being above any cloud during the maximum eclipse, allowing solar eclipse radiation measurements for comparison with theory. For the 20th March 2015 solar eclipse, a coordinated campaign of balloon-carried solar radiation measurements was undertaken from Reading (51.44N, 0.94W), Lerwick (60.15N, 1.13W) and Reykjavik (64.13N, 21.90W), straddling the path of the eclipse. All three balloons reached sufficient altitude at the eclipse time for eclipse-induced variations in solar radiation and solar limb darkening to be measured above cloud. Because the sensor platforms were free to swing, techniques have been evaluated to correct the measurements for their changing orientation. These approaches, which are essentially independent, give values that agree with theoretical expectations for the eclipse-induced radiation changes. [1] K.A. Nicoll and R.G. Harrison, Balloon-borne disposable radiometer Rev Sci Instrum 83, 025111 (2012) doi: 10.1063/1.3685252

  2. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1984-01-01

    The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hydrogen, the galactic photon density, and a revised cosmic ray galactic scale height, are included. The predictions are compared to the observational gamma ray longitude distributions, the latitude distribution, and energy spectrum, including the COS-B satellite results, and the COS-B background estimate. Considering the uncertainties, the agreement between the theoretical predictions and the gamma ray data seems generally reasonable, suggesting that the general concepts are likely to be correct. Both the results determined here alone and in conjunction with other work calculating source functions assuming only cosmic ray matter contributions indicate no necessity for a significant point source contribution to the diffuse gamma radiation in the energy range being considered (E(gamma)10 MeV). Previously announced in STAR as N84-18151

  3. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1984-01-01

    The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hydrogen, the galactic photon density, and a revised cosmic ray galactic scale height, are included. The predictions are compared to the observational gamma ray longitude distributions, the latitude distribution, and energy spectrum, including the COS-B satellite results, and the COS-B background estimate. Considering the uncertainties, the agreement between the theoretical predictions and the gamma ray data seems generally reasonable, suggesting that the general concepts are likely to be correct. Both the results determined here alone and in conjunction with other work calculating source functions assuming only cosmic ray matter contributions indicate no necessity for a significant point source contribution to the diffuse gamma radiation in the energy range being considered (E(gamma)10 MeV).

  4. The Gamma-ray galactic diffuse radiation and Cerenkov telescopes

    SciTech Connect

    Chardonnet, P. |; Salati, P. ||; Silk, J.; Grenier, I.; Smoot, G.

    1995-12-01

    By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

  5. Diffusion length variation and proton damage coefficients for InP/In(x)Ga(1-x)As/GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Weinberg, I.; Flood, D. J.

    1993-01-01

    Indium phosphide solar cells are more radiation resistant than gallium arsenide and silicon solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of lighter, mechanically strong and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5 and 3 MeV proton irradiations are explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence is calculated by simulating the cell performance. The diffusion length damage coefficient K(L) is plotted as a function of proton fluence.

  6. Materials That Enhance Efficiency and Radiation Resistance of Solar Cells

    NASA Technical Reports Server (NTRS)

    Sun, Xiadong; Wang, Haorong

    2012-01-01

    A thin layer (approximately 10 microns) of a novel "transparent" fluorescent material is applied to existing solar cells or modules to effectively block and convert UV light, or other lower solar response waveband of solar radiation, to visible or IR light that can be more efficiently used by solar cells for additional photocurrent. Meanwhile, the layer of fluorescent coating material remains fully "transparent" to the visible and IR waveband of solar radiation, resulting in a net gain of solar cell efficiency. This innovation alters the effective solar spectral power distribution to which an existing cell gets exposed, and matches the maximum photovoltaic (PV) response of existing cells. By shifting a low PV response waveband (e.g., UV) of solar radiation to a high PV response waveband (e.g. Vis-Near IR) with novel fluorescent materials that are transparent to other solar-cell sensitive wavebands, electrical output from solar cells will be enhanced. This approach enhances the efficiency of solar cells by converting UV and high-energy particles in space that would otherwise be wasted to visible/IR light. This innovation is a generic technique that can be readily implemented to significantly increase efficiencies of both space and terrestrial solar cells, without incurring much cost, thus bringing a broad base of economical, social, and environmental benefits. The key to this approach is that the "fluorescent" material must be very efficient, and cannot block or attenuate the "desirable" and unconverted" waveband of solar radiation (e.g. Vis-NIR) from reaching the cells. Some nano-phosphors and novel organometallic complex materials have been identified that enhance the energy efficiency on some state-of-the-art commercial silicon and thin-film-based solar cells by over 6%.

  7. Variation of solar cell sensitivity and solar radiation on tilted surfaces

    NASA Technical Reports Server (NTRS)

    Klucher, T. M.

    1978-01-01

    The validity is studied that one of various insolation models used to compute solar radiation incident on tilted surfaces from global data measured on horizontal surfaces. The variation of solar cell sensitivity to solar radiation is determined over a wide range of atmospheric condition. A new model was formulated that reduced the deviations between measured and predicted insolation to less than 3 percent. Evaluation of solar cell sensitivity data indicates small change (2-3 percent) in sensitivity from winter to summer for tilted cells. The feasibility of using such global data as a means for calibrating terrestrial solar cells is discussed.

  8. Diffused P+-N solar cells in bulk GaAs

    NASA Technical Reports Server (NTRS)

    Borrego, J. M.; Ghandhi, S. K.

    1982-01-01

    Recently melt grown GaAs, made by liquid encapsulation techniques, has become available. This material is of sufficiently good quality to allow the fabrication of solar cells by direct diffusion. Results obtained with p(+)/n junction solar cells made by zinc diffusion are described. The quality of bulk GaAs for this application is evaluated.

  9. Phytochemicals for prevention of solar ultraviolet radiation-induced damages.

    PubMed

    Adhami, Vaqar M; Syed, Deeba N; Khan, Naghma; Afaq, Farrukh

    2008-01-01

    While solar light is indispensable for sustenance of life, excessive exposure can cause several skin-related disorders. The UV part of solar radiation, in particular, is linked to disorders ranging from mild inflammatory effects of the skin to as serious as causing several different types of cancers. Changes in lifestyle together with depletion in the atmospheric ozone layer during the last few decades have led to an increase in the incidence of skin cancer. Skin cancers consisting of basal and squamous cell carcinomas are especially linked to the UVB part of solar radiation. Reducing excessive exposure to solar radiation is desirable; however, as this approach is unavoidable, it is suggested that other novel strategies be developed to reduce the effects of solar radiation to skin. One approach to reduce the harmful effects of solar radiation is through the use of phytochemicals, an approach that is popularly known as "Photochemoprotection." In recent years many phytochemicals with potential antioxidant properties have been identified and found to be photoprotective in nature. We describe here some of the most popular phytochemicals being studied that have the potential to reduce the harmful effects associated with solar UV radiation.

  10. A simple solar radiation index for wildlife habitat studies

    USGS Publications Warehouse

    Keating, Kim A.; Gogan, Peter J.; Vore, John N.; Irby, Lynn R.

    2007-01-01

    Solar radiation is a potentially important covariate in many wildlife habitat studies, but it is typically addressed only indirectly, using problematic surrogates like aspect or hillshade. We devised a simple solar radiation index (SRI) that combines readily available information about aspect, slope, and latitude. Our SRI is proportional to the amount of extraterrestrial solar radiation theoretically striking an arbitrarily oriented surface during the hour surrounding solar noon on the equinox. Because it derives from first geometric principles and is linearly distributed, SRI offers clear advantages over aspect-based surrogates. The SRI also is superior to hillshade, which we found to be sometimes imprecise and ill-behaved. To illustrate application of our SRI, we assessed niche separation among 3 ungulate species along a single environmental axis, solar radiation, on the northern Yellowstone winter range. We detected no difference between the niches occupied by bighorn sheep (Ovis canadensis) and elk (Cervus elaphus; P = 0.104), but found that mule deer (Odocoileus hemionus) tended to use areas receiving more solar radiation than either of the other species (P < 0.001). Overall, our SRI provides a useful metric that can reduce noise, improve interpretability, and increase parsimony in wildlife habitat models containing a solar radiation component.

  11. 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.

  12. Attitude Control Flight Experience: Coping with Solar Radiation and Ion Engines Leak Thrust in Hayabusa (MUSES-C)

    NASA Technical Reports Server (NTRS)

    Kawaguchi, Jun'ichiro; Kominato, Takashi; Shirakawa, Ken'ichi

    2007-01-01

    The paper presents the attitude reorientation taking the advantage of solar radiation pressure without use of any fuel aboard. The strategy had been adopted to make Hayabusa spacecraft keep pointed toward the Sun for several months, while spinning. The paper adds the above mentioned results reported in Sedona this February showing another challenge of combining ion engines propulsion tactically balanced with the solar radiation torque with no spin motion. The operation has been performed since this March for a half year successfully. The flight results are presented with the estimated solar array panel diffusion coefficient and the ion engine's swirl torque.

  13. A Theoretical Framework for Utilizing Long-Term Measurements of Radiation and Clouds for Solar Energy Research

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Xie, Y.

    2015-12-01

    One of the greatest challenges facing solar energy research is accurately predicting global horizontal irradiance (GHI) for photovoltaic (PV) modules and direct normal irradiance (DNI) for concentrated solar power (CSP) plants at the surface with a high temporal resolution. Addressing this solar energy challenge is tied ultimately to the quantitative relationship between the direct, diffuse and total radiation reaching the surface and clouds in the atmosphere, which remains elusive. Here we will first introduce a theoretical framework that relates DNI and GHI to cloud fraction and cloud albedo through two dimensionless numbers: the relative cloud radiative forcing for the direct radiation (defined as the difference between the clear sky and all sky direct downwelling radiative fluxes normalized by the clear sky direct downwelling radiative fluxes) is primarily determined by cloud fraction; the ratio of the relative cloud radiative forcing for the total downwelling radiation to the relative cloud radiative forcing for the direct radiation is primarily determined by cloud albedo. We then use decade-long measurements of partitioned radiation and cloud properties at the ARM sites to validate the theoretical relationships between the two dimensionless radiation-based parameters and cloud properties. We will also explore the potentials and challenges of using the relationships between cloud properties and radiation partition at the surface for solar energy research, opening new avenues to utilizing ARM measurements.

  14. Multidecadal solar radiation trends in the United States and Germany and direct tropospheric aerosol forcing

    NASA Astrophysics Data System (ADS)

    Liepert, Beate; Tegen, Ina

    2002-06-01

    In recent studies, anthropogenic aerosols have been recognized as important radiative forcing factors of climate because of their ability to scatter and/or absorb sunlight. At clear-sky conditions the direct aerosol forcing at ground is negative and implies less solar heating of the surface because of aerosols. In this study, an intensified direct aerosol forcing of -7 to -8 W/m2 has been detected in the United States for the interval from 1960 to 1990. In Germany a weakened aerosol forcing of +3 W/m2 was observed during the same time period. Even though the aerosol forcing is stronger in the eastern United States compared to the western United States, the positive trend is almost equal. We attained these results by scrutinizing clear-sky global solar radiation recordings for these regions and this time period. Additionally, the diurnal cycle and the direct to diffuse ratio of solar radiation were used for constraining the observed trends. Increased absorption and declined light scattering are presumably responsible for the intensified direct aerosol forcing in the United States. While at the same time in Germany, both aerosol absorption and scattering must have declined to explain the parallel weakened aerosol forcing and the increased direct/diffuse ratio. To estimate the possible anthropogenic portion of these observed changes, we compared the observational results with modeled aerosol forcing scenarios retrieved from the Goddard Institute for Space Studies general circulation model (GISS GCM). Modeled surface solar radiation, aerosol optical thickness, and single-scattering albedo are derived from emission trends of anthropogenic sulfate and carbonaceous aerosols. The emission distributions are calculated from fossil fuel consumption databases. On the basis of these simulations we suspect that the declining trend of sulfate burden over Germany between 1960 and 1990 was stronger than estimated with the model. Over the United States the simulated small increase

  15. Photosynthetically active radiation (PAR) x ultraviolet radiation (UV) interact to initiate solar injury in apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunburn or solar injury (SI) in apple is associated with high temperature, high visible light and ultraviolet radiation (UV). Fruit surface temperature (FST) thresholds for SI related disorders have been developed but there are no thresholds established for solar radiation. The objectives of the s...

  16. High voltage thermally diffused p(+)n solar cells

    NASA Technical Reports Server (NTRS)

    Faur, M.; Faur, M.; Flood, D. J.; Brinker, D. J.; Weinberg, I.; Goradia, C.; Fatemi, N.; Goradia, M.; Thesling, W.

    1991-01-01

    The possibility of fabricating thermally diffused p(+)n InP solar-cells with high open-circuit voltage without sacrificing the short circuit current is discussed. The p(+)n InP junctions were formed by Cd and Zn diffusion through a 3-5-nm-thick anodic or chemical phosphorus-rich oxide cap layer grown on n:InP:S (with ND-NA = 3.5 x 10 exp 16 and 4.5 x 10 exp 17/cu cm) Czochralski LEC-grown substrates. After thinning the emitter from its initial thickness of 1 to 2.5 micron down to 0.06-0.15 micron, the maximum efficiency was found when the emitter was 0.2 to 0.3 micron thick. Typical AM0, 25 C values of 854-860 mV were achieved for Voc, Jsc values were from 25.9 to 29.1 mA/sq cm using only the P-rich passivating layer left after the thinning process as an antireflection coating.

  17. Analysis of VIIRS TEB noise using solar diffuser measurements

    NASA Astrophysics Data System (ADS)

    Choi, Taeyoung; Cao, Changyong; Weng, Fuzhong

    2015-09-01

    The Soumi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) was launched on October 28th, 2011 and its Sensor Data Record (SDR) product reached maturity status in March of 2014. Although the VIIRS SDR products are declared at the validated maturity level, there remain issues such as residual stripings in some thermal bands along with the scan direction. These horizontal striping issues in the Thermal Emissive Bands (TEB) were reflected in the sea surface temperature (SST) products. The observed striping magnitude can reach to 0.2 K, especially at the band M14 and M15. As an independent source of calibration, the Solar Diffuser (SD) is utilized in this study. The SD is originally designed for the Reflective Solar Band (RSB), however, it is assumed to be thermally stable at the time of SD observation. For each detector, a linear slope is developed by Integrated Calibration and Validation System (ICVS), which is applied on converting digital number (DN) to radiance unit. After the conversion, detector based noise analyses in VIIRS band M15 and M16 are performed on in-scan and scan-by-scan SD responses. Since SD radiance varies within an orbit, the noise calculation must be derived from the neighborhood Allan deviation. The noise derived Allan deviation shows that detector 1 and 2 in band M15 and detector 9 in band M16 have higher noise content compared to other detectors.

  18. An economic evaluation of solar radiation management.

    PubMed

    Aaheim, Asbjørn; Romstad, Bård; Wei, Taoyuan; Kristjánsson, Jón Egill; Muri, Helene; Niemeier, Ulrike; Schmidt, Hauke

    2015-11-01

    Economic evaluations of solar radiation management (SRM) usually assume that the temperature will be stabilized, with no economic impacts of climate change, but with possible side-effects. We know from experiments with climate models, however, that unlike emission control the spatial and temporal distributions of temperature, precipitation and wind conditions will change. Hence, SRM may have economic consequences under a stabilization of global mean temperature even if side-effects other than those related to the climatic responses are disregarded. This paper addresses the economic impacts of implementing two SRM technologies; stratospheric sulfur injection and marine cloud brightening. By the use of a computable general equilibrium model, we estimate the economic impacts of climatic responses based on the results from two earth system models, MPI-ESM and NorESM. We find that under a moderately increasing greenhouse-gas concentration path, RCP4.5, the economic benefits of implementing climate engineering are small, and may become negative. Global GDP increases in three of the four experiments and all experiments include regions where the benefits from climate engineering are negative.

  19. The growth of solar radiated yeast

    SciTech Connect

    Kraft, T.

    1995-09-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  20. Denoising solar radiation data using coiflet wavelets

    SciTech Connect

    Karim, Samsul Ariffin Abdul Janier, Josefina B. Muthuvalu, Mohana Sundaram; Hasan, Mohammad Khatim; Sulaiman, Jumat; Ismail, Mohd Tahir

    2014-10-24

    Signal denoising and smoothing plays an important role in processing the given signal either from experiment or data collection through observations. Data collection usually was mixed between true data and some error or noise. This noise might be coming from the apparatus to measure or collect the data or human error in handling the data. Normally before the data is use for further processing purposes, the unwanted noise need to be filtered out. One of the efficient methods that can be used to filter the data is wavelet transform. Due to the fact that the received solar radiation data fluctuates according to time, there exist few unwanted oscillation namely noise and it must be filtered out before the data is used for developing mathematical model. In order to apply denoising using wavelet transform (WT), the thresholding values need to be calculated. In this paper the new thresholding approach is proposed. The coiflet2 wavelet with variation diminishing 4 is utilized for our purpose. From numerical results it can be seen clearly that, the new thresholding approach give better results as compare with existing approach namely global thresholding value.

  1. Public understanding of solar radiation management

    NASA Astrophysics Data System (ADS)

    Mercer, A. M.; Keith, D. W.; Sharp, J. D.

    2011-10-01

    We report the results of the first large-scale international survey of public perception of geoengineering and solar radiation management (SRM). Our sample of 3105 individuals in the United States, Canada and the United Kingdom was recruited by survey firms that administer internet surveys to nationally representative population samples. Measured familiarity was higher than expected, with 8% and 45% of the population correctly defining the terms geoengineering and climate engineering respectively. There was strong support for allowing the study of SRM. Support decreased and uncertainty rose as subjects were asked about their support for using SRM immediately, or to stop a climate emergency. Support for SRM is associated with optimism about scientific research, a valuing of SRM's benefits and a stronger belief that SRM is natural, while opposition is associated with an attitude that nature should not be manipulated in this way. The potential risks of SRM are important drivers of public perception with the most salient being damage to the ozone layer and unknown risks. SRM is a new technology and public opinions are just forming; thus all reported results are sensitive to changes in framing, future information on risks and benefits, and changes to context.

  2. The growth of solar radiated yeast

    NASA Technical Reports Server (NTRS)

    Kraft, Tyrone

    1995-01-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  3. An economic evaluation of solar radiation management.

    PubMed

    Aaheim, Asbjørn; Romstad, Bård; Wei, Taoyuan; Kristjánsson, Jón Egill; Muri, Helene; Niemeier, Ulrike; Schmidt, Hauke

    2015-11-01

    Economic evaluations of solar radiation management (SRM) usually assume that the temperature will be stabilized, with no economic impacts of climate change, but with possible side-effects. We know from experiments with climate models, however, that unlike emission control the spatial and temporal distributions of temperature, precipitation and wind conditions will change. Hence, SRM may have economic consequences under a stabilization of global mean temperature even if side-effects other than those related to the climatic responses are disregarded. This paper addresses the economic impacts of implementing two SRM technologies; stratospheric sulfur injection and marine cloud brightening. By the use of a computable general equilibrium model, we estimate the economic impacts of climatic responses based on the results from two earth system models, MPI-ESM and NorESM. We find that under a moderately increasing greenhouse-gas concentration path, RCP4.5, the economic benefits of implementing climate engineering are small, and may become negative. Global GDP increases in three of the four experiments and all experiments include regions where the benefits from climate engineering are negative. PMID:26057725

  4. Skin cancer and solar UV radiation.

    PubMed

    de Gruijl, F R

    1999-12-01

    Ultraviolet (UV) radiation in sunlight is the most prominent and ubiquitous physical carcinogen in our natural environment. It is highly genotoxic but does not penetrate the body any deeper than the skin. Like all organisms regularly exposed to sunlight, the human skin is extremely well adapted to continuous UV stress. Well-pigmented skin is clearly better protected than white Caucasian skin. The sun-seeking habits of white Caucasians in developed countries are likely to have contributed strongly to the increase in skin cancer observed over the last century. Skin cancer is by far the most common type of cancer in the U.S.A. and Australia, which appears to be the result of an 'unnatural displacement' of people with sun-sensitive skin to sub-tropical regions. Although campaigns have been successful in informing people about the risks of sun exposure, general attitudes and behaviour do not yet appear to have changed to the extent that trends in skin cancer morbidity and the corresponding burden on public healthcare will be reversed. The relationship between skin cancer and regular sun exposure was suspected by physicians in the late 19th century, and subsequently substantiated in animal experiments in the early part of the 20th century. UV radiation was found to be highly genotoxic, and DNA repair proved to be crucial in fending off detrimental effects such as mutagenesis and cell death. In fact, around 1940 it was shown that the wavelength dependence of mutagenicity paralleled the UV absorption by DNA. In the 1970s research on UV carcinogenesis received a new impetus from the arising concern about a possible future depletion of the stratospheric ozone layer: the resulting increases in ambient UV loads were expected to raise skin cancer incidences. Epidemiological studies in the last decades of the 20th century have greatly refined our knowledge on the aetiology of skin cancers. Analyses of gene mutations in skin carcinomas have identified UV radiation as the cause

  5. The atmospheric cosmic- and solar energetic particle radiation environment at aircraft altitudes.

    PubMed

    O'Brien, K; Friedberg, W; Smart, D F; Sauer, H H

    1998-01-01

    Galactic cosmic rays interact with the solar wind, the earth's magnetic field and hadron, lepton and photon fields at aircraft altitudes. In addition to cosmic rays, energetic particles generated by solar activity bombard the earth from time to time. These particles, while less energetic than cosmic rays, also produce radiation fields at aircraft altitudes which have qualitatively the same properties as atmospheric cosmic rays. We have used a code based on transport theory to calculate atmospheric cosmic-ray quantities and compared them with experimental data. Agreement with these data is seen to be good. We have then used this code to calculate equivalent doses to aircraft crews. We have also used the code to calculate radiation doses from several large solar energetic particle events which took place in 1989, including the very large event that occurred on September 29th and 30th of that year. The spectra incident on the atmosphere were determined assuming diffusive shock theory.

  6. Ecological study of solar radiation and cancer mortality in Japan.

    PubMed

    Mizoue, Tetsuya

    2004-11-01

    Geographic observation of the increased mortality of some cancers at higher latitudes has led to a hypothesis that vitamin D produced after exposure to solar radiation has anti-carcinogenic effects. However, it is unclear whether such association would be observed in countries like Japan, where fish consumption, and therefore dietary vitamin D intake, is high. Pearson correlation coefficients were calculated between averaged annual solar radiation levels for the period from 1961 through 1990 and cancer mortality in the year 2000 in 47 prefectures in Japan, with adjustments for regional per capita income and dietary factors. A moderate, inverse correlation with solar radiation was observed for cancers of the esophagus, stomach, colon, rectum, pancreas, and gallbladder and bile ducts in both sexes (correlation coefficient, ranging from -0.6 to -0.3). The results of this study support the hypothesis that increased exposure to solar radiation reduces the risk of cancers of the digestive organs. PMID:15551791

  7. National Solar Radiation Database 1991-2005 Update: User's Manual

    SciTech Connect

    Wilcox, S.

    2007-04-01

    This manual describes how to obtain and interpret the data products from the updated 1991-2005 National Solar Radiation Database (NSRDB). This is an update of the original 1961-1990 NSRDB released in 1992.

  8. National Solar Radiation Database 1991-2010 Update: User's Manual

    SciTech Connect

    Wilcox, S. M.

    2012-08-01

    This user's manual provides information on the updated 1991-2010 National Solar Radiation Database. Included are data format descriptions, data sources, production processes, and information about data uncertainty.

  9. Solar and Photovoltaic Data from the University of Oregon Solar Radiation Monitoring Laboratory (UO SRML)

    DOE Data Explorer

    The UO SRML is a regional solar radiation data center whose goal is to provide sound solar resource data for planning, design, deployment, and operation of solar electric facilities in the Pacific Northwest. The laboratory has been in operation since 1975. Solar data includes solar resource maps, cumulative summary data, daily totals, monthly averages, single element profile data, parsed TMY2 data, and select multifilter radiometer data. A data plotting program and other software tools are also provided. Shade analysis information and contour plots showing the effect of tilt and orientation on annual solar electric system perfomance make up a large part of the photovoltaics data.(Specialized Interface)

  10. Modelling thermal radiation in buoyant turbulent diffusion flames

    NASA Astrophysics Data System (ADS)

    Consalvi, J. L.; Demarco, R.; Fuentes, A.

    2012-10-01

    This work focuses on the numerical modelling of radiative heat transfer in laboratory-scale buoyant turbulent diffusion flames. Spectral gas and soot radiation is modelled by using the Full-Spectrum Correlated-k (FSCK) method. Turbulence-Radiation Interactions (TRI) are taken into account by considering the Optically-Thin Fluctuation Approximation (OTFA), the resulting time-averaged Radiative Transfer Equation (RTE) being solved by the Finite Volume Method (FVM). Emission TRIs and the mean absorption coefficient are then closed by using a presumed probability density function (pdf) of the mixture fraction. The mean gas flow field is modelled by the Favre-averaged Navier-Stokes (FANS) equation set closed by a buoyancy-modified k-ɛ model with algebraic stress/flux models (ASM/AFM), the Steady Laminar Flamelet (SLF) model coupled with a presumed pdf approach to account for Turbulence-Chemistry Interactions, and an acetylene-based semi-empirical two-equation soot model. Two sets of experimental pool fire data are used for validation: propane pool fires 0.3 m in diameter with Heat Release Rates (HRR) of 15, 22 and 37 kW and methane pool fires 0.38 m in diameter with HRRs of 34 and 176 kW. Predicted flame structures, radiant fractions, and radiative heat fluxes on surrounding surfaces are found in satisfactory agreement with available experimental data across all the flames. In addition further computations indicate that, for the present flames, the gray approximation can be applied for soot with a minor influence on the results, resulting in a substantial gain in Computer Processing Unit (CPU) time when the FSCK is used to treat gas radiation.

  11. Radiation forces on small particles in the solar system

    NASA Technical Reports Server (NTRS)

    Burns, J. A.; Lamy, P. L.; Soter, S.

    1979-01-01

    Solar radiation forces on small particles in the solar system are examined, and the resulting orbital evolution of interplanetary and circumplanetary dust is considered. An expression is derived for the effects of radiation pressure and Poynting-Robertson drag on small, spherical particles using the energy and momentum transformation laws of special relativity, and numerical examples are presented to illustrate that radiation pressure and Poynting-Robertson drag are only important for particles within a narrow size range. The orbital consequences of these radiation forces are considered both for heliocentric and planetocentric orbiting particles, and the coupling between particle sizes and dynamics is discussed. A qualitative derivation is presented for the differential Doppler effect, which is due to the differential Doppler shifting of radiation from approaching and receding solar hemispheres, and the Yarkovsky effect, which is important for rotating meter-to kilometer-sized particles, is briefly described.

  12. Sunspot bright rings and the thermal diffusivity of solar convection

    NASA Technical Reports Server (NTRS)

    Duvall, T., Jr.; Fowler, L. A.; Foukal, P.

    1983-01-01

    Raster-scan observations of 10 sunspots, made in 1980 and 1981 with the 512-channel diode array and vacuum telescope at the Kitt Peak National Observatory, are reported. Data from several 10-min scans of 0.25-A passbands of clean continuum were summed to give an rms noise level of 0.25 percent, corrected by applying a limb-darkening curve, and analyzed to determine the average intensity for each of eight segments of a series of concentric rings around each sunspot. Faculae and pores were identified and discarded in constructing radial intensity profiles. Marginally significant bright symmetric rings (peak amplitude 0.1-0.3 percent) not attributable to residual facular signal or instrumental effects were observed around 6 of 10 sunspots. No evidence of more intense bright rings was found. These findings are discussed in terms of thermal-diffusion models proposed to explain the fate of the radiative flux blocked by sunspots.

  13. Methodology to estimate variations in solar radiation reaching densely forested slopes in mountainous terrain

    NASA Astrophysics Data System (ADS)

    Sypka, Przemysław; Starzak, Rafał; Owsiak, Krzysztof

    2016-05-01

    Solar radiation reaching densely forested slopes is one of the main factors influencing the water balance between the atmosphere, tree stands and the soil. It also has a major impact on site productivity, spatial arrangement of vegetation structure as well as forest succession. This paper presents a methodology to estimate variations in solar radiation reaching tree stands in a small mountain valley. Measurements taken in three inter-forest meadows unambiguously showed the relationship between the amount of solar insolation and the shading effect caused mainly by the contour of surrounding tree stands. Therefore, appropriate knowledge of elevation, aspect and tilt angles of the analysed planes had to be taken into consideration during modelling. At critical times, especially in winter, the diffuse and reflected components of solar radiation only reached some of the sites studied as the beam component of solar radiation was totally blocked by the densely forested mountain slopes in the neighbourhood. The cross-section contours and elevation angles of all obstructions are estimated from a digital surface model including both digital elevation model and the height of tree stands. All the parameters in a simplified, empirical model of the solar insolation reaching a given horizontal surface within the research valley are dependent on the sky view factor (SVF). The presented simplified, empirical model and its parameterisation scheme should be easily adaptable to different complex terrains or mountain valleys characterised by diverse geometry or spatial orientation. The model was developed and validated (R 2 = 0.92 , σ = 0.54) based on measurements taken at research sites located in the Silesian Beskid Mountain Range. A thorough understanding of the factors determining the amount of solar radiation reaching woodlands ought to considerably expand the knowledge of the water exchange balance within forest complexes as well as the estimation of site productivity.

  14. Modeling topographic influences on solar radiation: A manual for the SOLARFLUX Model

    SciTech Connect

    Rich, P.M.; Hetrick, W.A.; Saving, S.C.

    1995-11-01

    SOLARFLUX is a geographical information system (GIS) based computer program (running under ARC/INFO and GRID) that models incoming solar radiation based on surface orientation (slope and aspect), solar angle (azimuth and zenith) as it shifts over time, shadows caused by topographic features, and atmospheric conditions. A convenient user interface allows specification of program parameters including latitude, time interval for simulation, file name of a topographic surface, atmospheric conditions (transmittivity), and file names for output. The user specifies a topographic surface as an array of elevation values (GRID). SOLARFLUX generates five basic types of output: 1) total direct radiation, 2) duration of direct sunlight, 3) total diffuse radiation, 4) skyview factor, and 5) hemispherical viewsheds of sky obstruction for specified surface locations. This manual serves as the comprehensive guide to SOLARFLUX. Included are discussions on modeling insolation on complex surfaces, our theoretical approach, program setup and operation, and a set of applications illustrating characteristics of topographic insolation modeling.

  15. Experimental and computer studies of the radiation effects in silicon solar cells

    NASA Technical Reports Server (NTRS)

    Leadon, R. E.; Naber, J. A.; Passenheim, B. C.

    1971-01-01

    A summary of selected experimental results obtained on lithium-diffused bulk silicon is presented. Particular emphasis is placed on the radiation-induced degradation and thermal annealing of minority carriers in bulk silicon because solar cell output is related to the minority carrier lifetime. The temperature dependence of the minority carrier lifetime indicates the density and energy levels of the recombination centers and provides clues to their identity. Electron spin resonance and infrared absorption techniques are used to investigate the introduction and anneal of three specific radiation induced defects, which are thought to contribute to the recombination process.

  16. Absorption of solar radiation by clouds: observations versus models.

    PubMed

    Cess, R D; Zhang, M H; Minnis, P; Corsetti, L; Dutton, E G; Forgan, B W; Garber, D P; Gates, W L; Hack, J J; Harrison, E F; Jing, X; Kiehi, J T; Long, C N; Morcrette, J J; Potter, G L; Ramanathan, V; Subasilar, B; Whitlock, C H; Young, D F; Zhou, Y

    1995-01-27

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  17. Absorption of Solar Radiation by Clouds: Observations Versus Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Minnis, P.; Corsetti, L.; Dutton, E. G.; Forgan, B. W.; Garber, D. P.; Gates, W. L.; Hack, J. J.; Harrison, E. F.; Jing, X.; Kiehl, J. T.; Long, C. N.; Morcrette, J.-J.; Potter, G. L.; Ramanathan, V.; Subasilar, B.; Whitlock, C. H.; Young, D. F.; Zhou, Y.

    1995-01-01

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  18. Solar radiation pressure effects on the Helios spacecraft

    NASA Technical Reports Server (NTRS)

    Georgevic, R. M.

    1976-01-01

    A mathematical model of the solar radiation force and torques, developed for the Mariner 10 Venus/Mercury spacecraft mission, was used for a detailed analysis of the effects of solar light pressure on the Helios spacecraft. Due to the fact that the main body of the Helios spacecraft is a surface of enclosure, inside of which most of the reradiated thermal energy is lost, expressions for the portion of the solar radiation force, produced by the thermal reradiation, had to be given a different form. Hence the need for the derivation of a somewhat different theoretical model for the force acting on the main body of the spacecraft.

  19. Impact of Changes in Diffuse Radiation on the Global Land Carbon Sink, 1901-2100

    NASA Astrophysics Data System (ADS)

    Mercado, L.; Bellouin, N.; Sitch, S.; Boucher, O.; Huntingford, C.; Wild, M.; Cox, P. M.

    2009-04-01

    Recent observational and theoretical studies have shown that changes in surface radiation that lead to increasing diffuse surface irradiance, enhance plant photosynthesis (Gu et al., 2003, Niyogi et al., 2004, Oliveira et al., 2007, Roderick et al., 2001). Solar radiation reaching the land surface has changed over the industrial era due to aerosols emitted from volcanoes and various anthropogenic sources (Kvalevag and Myhre, 2007). Such changes in total surface radiation are accompanied by changes in direct and diffuse surface solar radiation. Current global climate-carbon models do include the effects of changes in total surface radiation on the land biosphere but neglect the positive effects of increasing diffuse fraction on plant photosynthesis. In this study we estimate for the first time, the impact of variations in diffuse fraction on the land carbon sink using a global model (Mercado et al., 2007) modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We use meteorological forcing from the Climate Research Unit Data set. Additionally short wave and photosynthetic active radiation are reconstructed from the Hadley centre climate model, which accounts for the scattering and absorption of light by tropospheric and stratospheric aerosols and change in cloud properties due to indirect aerosol effects. References Gu L.H., Baldocchi D.D., Wofsy S.C., Munger J.W., Michalsky J.J., Urbanski S.P. & Boden T.A. (2003) Response of a deciduous forest to the Mount Pinatubo eruption: Enhanced photosynthesis. Science, 299, 2035-2038. M. M. Kvalevag and G. Myhre, J. Clim. 20, 4874 (2007). Mercado L.M., Huntingford C., Gash J.H.C., Cox P.M. & Jogireddy V. (2007) Improving the representation of radiation interception and photosynthesis for climate model applications. Tellus Series B-Chemical and Physical Meteorology, 59, 553-565. Niyogi D., Chang H.I., Saxena V.K., Holt T., Alapaty K., Booker F., Chen F., Davis K

  20. The effects of solar radiation and black body re-radiation on thermal comfort.

    PubMed

    Hodder, Simon; Parsons, Ken

    2008-04-01

    When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces

  1. The effects of solar radiation and black body re-radiation on thermal comfort.

    PubMed

    Hodder, Simon; Parsons, Ken

    2008-04-01

    When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces.

  2. Exposure to galactic cosmic radiation and solar energetic particles.

    PubMed

    O'Sullivan, D

    2007-01-01

    Several investigations of the radiation field at aircraft altitudes have been undertaken during solar cycle 23 which occurred in the period 1993-2003. The radiation field is produced by the passage of galactic cosmic rays and their nuclear reaction products as well as solar energetic particles through the Earth's atmosphere. Galactic cosmic rays reach a maximum intensity when the sun is least active and are at minimum intensity during solar maximum period. During solar maximum an increased number of coronal mass ejections and solar flares produce high energy solar particles which can also penetrate down to aircraft altitudes. It is found that the very complicated field resulting from these processes varies with altitude, latitude and stage of solar cycle. By employing several active and passive detectors, the whole range of radiation types and energies were encompassed. In-flight data was obtained with the co-operation of many airlines and NASA. The EURADOS Aircraft Crew in-flight data base was used for comparison with the predictions of various computer codes. A brief outline of some recent studies of exposure to radiation in Earth orbit will conclude this contribution. PMID:17846031

  3. Exposure to galactic cosmic radiation and solar energetic particles.

    PubMed

    O'Sullivan, D

    2007-01-01

    Several investigations of the radiation field at aircraft altitudes have been undertaken during solar cycle 23 which occurred in the period 1993-2003. The radiation field is produced by the passage of galactic cosmic rays and their nuclear reaction products as well as solar energetic particles through the Earth's atmosphere. Galactic cosmic rays reach a maximum intensity when the sun is least active and are at minimum intensity during solar maximum period. During solar maximum an increased number of coronal mass ejections and solar flares produce high energy solar particles which can also penetrate down to aircraft altitudes. It is found that the very complicated field resulting from these processes varies with altitude, latitude and stage of solar cycle. By employing several active and passive detectors, the whole range of radiation types and energies were encompassed. In-flight data was obtained with the co-operation of many airlines and NASA. The EURADOS Aircraft Crew in-flight data base was used for comparison with the predictions of various computer codes. A brief outline of some recent studies of exposure to radiation in Earth orbit will conclude this contribution.

  4. New typical meterological years and solar radiation data manual

    SciTech Connect

    Marion, W.

    1995-09-01

    A new solar radiation data manual and new typical meterological years (TMYs) were developed by the National Renewable Energy Laboratory (NREL) Analytic Studies Division under the Solar Radiation Resource Assessment Project. These tasks were funded and monitored by the Photovoltaics Branch of the Department of Energy Office of Energy Efficiency and Renewable Energy. The new manual and the new TMYs were derived from the 1961-1990 National Solar Radiation Data Base (NSRDB). The new manual is entitled Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors. It provides designers and engineers of solar-energy-related systems with average monthly and yearly solar radiation values for various types of collectors for 239 stations in the United States and its territories. The new TMY data sets are referred to as TMY2s. This distinguishes them from earlier TMY data sets derived from the 1952-1975 SOLMET/ERSATZ data base. This paper describes the new data manual and the new TMY2s.

  5. Solar radiation interactions with seasonal sea ice

    NASA Astrophysics Data System (ADS)

    Ehn, Jens Kristian

    Presently, the Arctic Ocean is undergoing an escalating reduction in sea ice and a transition towards a seasonal sea ice environment. This warrants detailed investigations into improving our understanding of the seasonal evolution of sea ice and snow covers, and their representation in climate models. The interaction of solar radiation with sea ice is an important process influencing the energy balance and biological activity in polar seas, and consequently plays a key role in the earth's climate system. This thesis focuses on characterization of the optical properties---and the underlying physical properties that determine them---of seasonal sea ice during the fall freeze-up and the spring melt periods. Both periods display high spatial heterogeneity and rapid temporal changes in sea ice properties, and are therefore poorly understood. Field data were collected in Amundsen Gulf/Franklin Bay (FB), southern-eastern Beaufort Sea, in Oct.-Nov. 2003 and Apr. 2004 and in Button Bay (BB), western Hudson Bay, in Mar.-May 2005 to address (1) the temporal and spatial evolution of surface albedo and transmittance, (2) how radiative transfer in sea ice is controlled by its physical nature, and (3) the characteristics of the bottom ice algae community and its effect on the optical properties. The fall study showed the importance of surface features such as dry or slushy bare ice, frost flowers and snow cover in determining the surface albedo. Ice thickness was also important, however, mostly because surface features were associated with thickness. For example, nilas (<10 cm thick) was typically not covered by a snow layer as snow grains were dissolved or merged with the salty and warm brine skim layer on the surface, while surface conditions on thicker ice types were cold and dry enough to support a snow cover. In general, the surface albedo increased exponentially with an ice thickness increase, however, variability within ice thickness types were very large. It is apparent

  6. Radiator selection for Space Station Solar Dynamic Power Systems

    NASA Astrophysics Data System (ADS)

    Fleming, Mike; Hoehn, Frank

    A study was conducted to define the best radiator for heat rejection of the Space Station Solar Dynamic Power System. Included in the study were radiators for both the Organic Rankine Cycle and Closed Brayton Cycle heat engines. A number of potential approaches were considered for the Organic Rankine Cycle and a constructable radiator was chosen. Detailed optimizations of this concept were conducted resulting in a baseline for inclusion into the ORC Preliminary Design. A number of approaches were also considered for the CBC radiator. For this application a deployed pumped liquid radiator was selected which was also refined resulting in a baseline for the CBC preliminary design. This paper reports the results and methodology of these studies and describes the preliminary designs of the Space Station Solar Dynamic Power System radiators for both of the candidate heat engine cycles.

  7. Effect of diffusion current on fill factor in organic solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Haomiao; Yi, Ruichen; Zhang, Jiawei; Yu, Anran; Peng, Huan; Qin, Jiajun; Hou, Xiaoyuan

    2016-05-01

    To identify the effect of drift/diffusion current on the fill factor (FF) of organic solar cells, the correlation between FF and drift/diffusion current is studied with thickness/type of donor material, temperature and doping as the experimental parameters. Experimental results show that FF is positively related to the diffusion current. Because of the suppression of carrier diffusion, generated carriers will accumulate at the donor-acceptor interface, resulting in carrier recombination.

  8. Correlations between solar wind parameters and auroral kilometric radiation intensity

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Dangelo, N.

    1981-01-01

    The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

  9. Increased radiation resistance in lithium-counterdoped silicon solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Mehta, S.

    1984-01-01

    Lithium-counterdoped n(+)p silicon solar cells are found to exhibit significantly increased radiation resistance to 1-MeV electron irradiation when compared to boron-doped n(+)p silicon solar cells. In addition to improved radiation resistance, considerable damage recovery by annealing is observed in the counterdoped cells at T less than or equal to 100 C. Deep level transient spectroscopy measurements are used to identify the defect whose removal results in the low-temperature aneal. It is suggested that the increased radiation resistance of the counterdoped cells is primarily due to interaction of the lithium with interstitial oxygen.

  10. A study of thermal radiation transfer in a solar thruster

    SciTech Connect

    Venkateswaran, S.; Thynell, S.T.; Merkle, C.L. )

    1991-11-01

    Combined convective and radiative heat transfer in an axisymmetric solar thruster is analyzed. In a solar thruster, focused solar energy is converted into thermal energy by volumetric absorption, resulting in a significant increase in the temperature of the propellant gas. The heated gas is then expanded through a propulsive nozzle in order to generate thrust. In the present theoretical analysis, submicron size particles are employed for providing the mechanism of solar energy absorption. The two-dimensional radiation problem is solved using both an exact integral method and the P{sub 1}-approximation. The overall energy transfer is solved iteratively by numerical means. The computational model is used to perform parametric studies of the effects of Boltzmann number, optical dimensions of the medium, and wall emissivity. The overall performance of the solar thruster is assessed by determining the thrust levels and the specific impulses of the device under different operating conditions.

  11. Characteristics of the earth radiation budget experiment solar monitors

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Barkstrom, Bruce R.; Cess, Robert D.

    1987-01-01

    The earth radiation budget experiment solar monitors, active cavity pyrheliometers, have been developed to measure every two weeks the total optical solar irradiance from the earth radiation budget satellite (ERBS) and the National Oceanic and Atmospheric Administration NOAA-9 spacecraft platforms. In the unfiltered 0.2-50-micron wavelength broadband region, the monitors were used to obtain 1365 W/sq m as the mean value for the solar irradiance, with measurement precisions and accuracies approaching 0.1 and 0.2 percent, respectively. The design and characteristics of the solar monitors are presented along with the data reduction model. For the October 1984 through July 1985 period, the resulting ERBS and NOAA-9 solar irradiance values are intercompared.

  12. Observed ozone response to variations in solar ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Gille, J. C.; Smythe, C. M.; Heath, D. F.

    1984-01-01

    During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers.

  13. TEMPORAL AND SPATIAL VARIATION IN SOLAR RADIATION AND PHOTO-ENHANCED TOXICITY RISKS OF SPILLED OIL IN PRINCE WILLIAM SOUND, ALASKA

    EPA Science Inventory

    Solar irradiance (W/m2) and downwelling diffuse attenuation coefficients (Kd; m-1) were determined in several locations in Prince William Sound, Alaska, USA, between April 2003 and December 2005 to assess temporal and spatial variation in solar radiation and the risks of photoenh...

  14. Multi-spacecraft observations of energetic solar particles: effect of perpendicular diffusion

    NASA Astrophysics Data System (ADS)

    Kartavykh, Yulia; Droege, Wolfgang; Klecker, Berndt; Kovaltsov, Gennady; Heber, Bernd

    Spacecraft observations of impulsive solar particle events under different angles from the accel-eration source on the Sun provide information on perpendicular diffusion in the interplanetary magnetic field. We will present results of our transport model which includes pitch angle dif-fusion, focusing, pitch-angle dependent diffusion perpendicular to the magnetic field, adiabatic deceleration and convection in the solar wind. We will in particular discuss the dependence of the shapes of the observed time profiles on the azimuthal distance of the spacecraft and compare predictions of our model with data of multi-spacecraft observations of solar particles from Helios and Stereo.

  15. Hourly global and diffuse radiation of Lagos, Nigeria-correlation with some atmospheric parameters

    SciTech Connect

    Chendo, M.A.C.; Maduekwe, A.A.L. )

    1994-03-01

    The influence of four climatic parameters on the hourly diffuse fraction in Lagos, Nigeria, has been studied. Using data for two years, new correlations were established. The standard error of the Liu and Jordan-type equation was reduced by 12.83% when solar elevation, ambient temperature, and relative humidity were used together as predictor variables for the entire data set. Ambient temperature and relative humidity proved to be very important variables for predicting the diffuse fraction of the solar radiation passing through the humid atmosphere of the coastal and tropic city of Lagos. Seasonal analysis carried out with the data showed improvements on the standard errors for the new seasonal correlations. In the case of the dry season, the improvement was 18.37%, whole for the wet season, this was 12.37%. Comparison with existing correlations showed that the performance of the one parameter model (namely K[sub t]), of Orgill and Hollands and Reindl, Beckman, and Duffie were very different from the Liu and Jordan-type model obtained for Lagos.

  16. Status of Diffused Junction p(+)n InP Solar Cells for Space Applications

    NASA Technical Reports Server (NTRS)

    Faur, Mircea; Faur, Maria; Flood, D. J.; Brinker, D. J.; Goradia, C.; Fatemi, N. S.; Jenkins, P. P.; Wilt, D. M.; Bailey, S.

    1994-01-01

    Recently, we have succeeded in fabricating diffused junction p(+)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3%. The maximum AMO, 25 C efficiency recorded to date on bare cells is, however, only 13.2%. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(+)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: 1) the formation of thin p(+) InP:Cd emitter layers, 2) electroplated front contacts, 3) surface passivation and 4) the design of a new native oxide/AI203/MgF2 three layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.

  17. Status of diffused junction p+n InP solar cells for space applications

    NASA Technical Reports Server (NTRS)

    Faur, Mircea; Goradia, C.; Faur, Maria; Fatemi, N. S.; Jenkins, P. P.; Flood, D. J.; Brinker, D. J.; Wilt, D. M.; Bailey, S.; Goradia, M.

    1994-01-01

    Recently, we have succeeded in fabricating diffused junction p(sup +)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3 percent. The maximum AMO, 25 C internal losses due to date on bare cells is, however, only 13.2 percent. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(sup +)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: (1) the formation on thin p(sup +) InP:Cd emitter layers, (2) electroplated front contacts, (3) surface passivation and (4) the design of a new native oxide/Al2O3/MgF2 tree layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.

  18. 'Averaged' Diffusion of Radiation in Spectral Lines intra Interjacent Plasma-Gas Layer

    SciTech Connect

    Demura, A. V.; Demchenko, G. V.

    2008-10-22

    The approximate model of 'averaged diffusion' for resonance radiation transfer is introduced. It allows to reduce computational efforts preserving satisfactory accuracy while modeling divertor plasmas.

  19. Solar Origin of Solar Particle Events Detected by the Standard Radiation Environment Monitor of ESA

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.; Sandberg, I.; Anastasiadis, A.; Daglis, I. A.; Panagopoulos, I.; Mavromichalaki, H.; Papaioannou, A.; Gerontidou, M.; Nieminen, P.; Glover, A.

    2010-07-01

    Solar Particle Events (SPEs) of the 23rd Solar Cycle detected by the ESA Standard Radiation Environment Monitor (SREM) onboard the INTEGRAL satellite have been studied in order to find their connection to solar sources. X-ray, optical and radio data of solar flares that were observed by several space-based instruments during the aforementioned solar cycle have been selected. The data were reduced and thoroughly analyzed in order to establish the corresponding solar origin of the selected SPEs. The extensive scientific analysis has produced clear correlations with X class solar flares for the events of the October-November 2003, January 2005 and December 2006 periods while for the events that occurred during September 2005, correlations with X class flares are possible but not straightforward due to the complexity of the registered solar particle fluxes.

  20. Soot and Radiation Measurements in Microgravity Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.

    1996-01-01

    The subject of soot formation and radiation heat transfer in microgravity jet diffusion flames is important not only for the understanding of fundamental transport processes involved but also for providing findings relevant to spacecraft fire safety and soot emissions and radiant heat loads of combustors used in air-breathing propulsion systems. Our objectives are to measure and model soot volume fraction, temperature, and radiative heat fluxes in microgravity jet diffusion flames. For this four-year project, we have successfully completed three tasks, which have resulted in new research methodologies and original results. First is the implementation of a thermophoretic soot sampling technique for measuring particle size and aggregate morphology in drop-tower and other reduced gravity experiments. In those laminar flames studied, we found that microgravity soot aggregates typically consist of more primary particles and primary particles are larger in size than those under normal gravity. Comparisons based on data obtained from limited samples show that the soot aggregate's fractal dimension varies within +/- 20% of its typical value of 1.75, with no clear trends between normal and reduced gravity conditions. Second is the development and implementation of a new imaging absorption technique. By properly expanding and spatially-filtering the laser beam to image the flame absorption on a CCD camera and applying numerical smoothing procedures, this technique is capable of measuring instantaneous full-field soot volume fractions. Results from this technique have shown the significant differences in local soot volume fraction, smoking point, and flame shape between normal and reduced gravity flames. We observed that some laminar flames become open-tipped and smoking under microgravity. The third task we completed is the development of a computer program which integrates and couples flame structure, soot formation, and flame radiation analyses together. We found good

  1. Solar neutrinos and the influence of radiative opacities on solar models

    NASA Technical Reports Server (NTRS)

    Carson, T. R.; Ezer, D.; Stothers, R.

    1973-01-01

    Use of new radiative opacities based on the hot Thomas-Fermi model of the atom yields a predicted solar neutrino flux which is still considerably larger than the flux observed in Davis's Cl-37 experiment.

  2. Newton-Krylov methods applied to nonequilibrium radiation diffusion

    SciTech Connect

    Knoll, D.A.; Rider, W.J.; Olsen, G.L.

    1998-03-10

    The authors present results of applying a matrix-free Newton-Krylov method to a nonequilibrium radiation diffusion problem. Here, there is no use of operator splitting, and Newton`s method is used to convert the nonlinearities within a time step. Since the nonlinear residual is formed, it is used to monitor convergence. It is demonstrated that a simple Picard-based linearization produces a sufficient preconditioning matrix for the Krylov method, thus elevating the need to form or store a Jacobian matrix for Newton`s method. They discuss the possibility that the Newton-Krylov approach may allow larger time steps, without loss of accuracy, as compared to an operator split approach where nonlinearities are not converged within a time step.

  3. The relationship between Saturn kilometric radiation and the solar wind

    NASA Technical Reports Server (NTRS)

    Desch, M. D.; Rucker, H. O.

    1983-01-01

    Voyager spacecraft radio, interplanetary plasma, and interplanetary magnetic field data are used to show that large amplitude fluctuations in the power generated by the Saturn kilometric radio emission are best correlated with solar wind ram pressure variation. In all, thirteen solar wind quantities previously found important in driving terrestrial magnetospheric substorms and other auroral processes were examined for evidence of correlations with the Saturn radio emission. The results are consistent with hydromagnetic wave or eddy diffusion processes driven by large scale solar wind pressure changes at Saturn's dayside magnetopause.

  4. Quality control of solar radiation data within the RMIB solar measurements network

    SciTech Connect

    Journee, Michel; Bertrand, Cedric

    2011-01-15

    Assessment of the solar resource is based upon measured data, where available. However, with any measurement there exist errors. Consequently, solar radiation data do not exhibit necessarily the same reliability and it often happens that users face time series of measurements containing questionable values though preliminary technical control has been done before the data release. To overcome such a situation, a major effort has been undertaken at the Royal Meteorological Institute of Belgium (RMIB) to develop procedures and software for performing post-measurement quality control of solar data from the radiometric stations of our in situ solar monitoring network. Moreover, because solar energy applications usually need continuous time series of solar radiation data, additional procedures have also been established to fill missing values (data initially lacking or removed via quality checks). (author)

  5. Effects of total solar eclipse of 29 March 2006 on surface radiation

    NASA Astrophysics Data System (ADS)

    Kazadzis, S.; Bais, A.; Blumthaler, M.; Webb, A.; Kouremeti, N.; Kift, R.; Schallhart, B.; Kazantzidis, A.

    2007-06-01

    Solar irradiance spectral measurements were performed during a total solar eclipse. The spectral effect of the limb darkening to the global, direct irradiance and actinic flux measurements was investigated. This effect leads to wavelength dependent changes in the measured solar spectra showing a much more pronounced decrease in the radiation at the lower wavelengths. Radiative transfer model results were used for the computation of a correction for the total ozone measurements due to the limb darkening. This correction was found too small to explain the large decrease in total ozone column derived from the standard Brewer measurements, which is an artifact in the measured irradiance due to the increasing contribution of diffuse radiation against the decreasing direct irradiance caused by the eclipse. Calculations of the Extraterrestrial spectrum and the effective sun's temperatures, as measured from ground based direct irradiance measurements, showed an artificial change in the calculations of both quantities due to the fact that radiation coming from the visible part of the sun during the eclipse phases differs from the back body radiation described by the Planck's law.

  6. Effects of total solar eclipse of 29 March 2006 on surface radiation

    NASA Astrophysics Data System (ADS)

    Kazadzis, S.; Bais, A.; Blumthaler, M.; Webb, A.; Kouremeti, N.; Kift, R.; Schallhart, B.; Kazantzidis, A.

    2007-11-01

    Solar irradiance spectral measurements were performed during a total solar eclipse. The spectral effect of the limb darkening to the global, direct irradiance and actinic flux measurements was investigated. This effect leads to wavelength dependent changes in the measured solar spectra showing a much more pronounced decrease in the radiation at the lower wavelengths. Radiative transfer model results were used for the computation of a correction for the total ozone measurements due to the limb darkening. This correction was found too small to explain the large decrease in total ozone column derived from the standard Brewer measurements, which is an artifact in the measured irradiance due to the increasing contribution of diffuse radiation against the decreasing direct irradiance caused by the eclipse. Calculations of the Extraterrestrial spectrum and the effective sun's temperatures, as measured from ground based direct irradiance measurements, showed an artificial change in the calculations of both quantities due to the fact that radiation coming from the visible part of the sun during the eclipse phases differs from the black body radiation described by the Planck's law.

  7. Solar Radiation Pressure and Attitude Modeling of GNSS Satellites

    NASA Astrophysics Data System (ADS)

    Rodriguez-Solano, C.; Hugentobler, U.; Steigenberger, P.

    2011-12-01

    The main non-gravitational orbit perturbation acting on GNSS satellites is the solar radiation pressure. There are two main approaches to model this force: 1) adjusting empirical parameters that fit best the GNSS tracking data, and 2) computing the a priori force from analytical models based on the detailed satellite structure and information available on ground. The first approach is not based on the physical interaction between solar radiation and the satellite, while the second one cannot be easily adjusted to the real on-orbit behaviour of the satellites, e.g., changes due to aging of optical properties or deviations from nominal attitude. We use here an intermediate approach, an analytical box-wing model based on the physical interaction between the solar radiation and a satellite consisting of a bus (box shape) and solar panels. Furthermore, some of the parameters of the box-wing model can be adjusted to fit the GNSS tracking data, namely the optical properties of the satellite surfaces. It was found that a pure box-wing model interacting with solar radiation is not sufficient for precise orbit determination. In particular a rotation lag angle of the solar panels was identified. This deviation of the solar panels from nominal attitude is a key factor to obtain precise GNSS orbits. Moreover, the yaw attitude of GNSS satellites during eclipse seasons deviates from nominal attitude due to maneuvers performed by the satellites. As mentioned in other studies, the phase measurements are degraded if these maneuvers are not taken into account since the modelled position of the navigation antenna may differ from the true position. In this study we focus on the impact of the yaw attitude on the solar radiation pressure parameters and the benefits for precise orbit determination and prediction.

  8. Solar Radiation Management and Olivine Dissolution Methods in Climate Engineering

    NASA Astrophysics Data System (ADS)

    Kone, S.

    2014-12-01

    An overview of solar radiation management and olivine dissolution methods allows to discuss, comparatively, the benefits and consequences of these two geoengineering techniques. The combination of those two techniques allows to concomitantly act on the two main agents intervening in global warming: solar radiation and carbon dioxide. The earth surface temperature increases due mainly to carbon dioxide (a greenhouse gas) that keeps the solar radiation and causes the global warming. Two complementary methods to mitigate climate change are overviewed: SRM method, which uses injected aerosols, aims to reduce the amount of the inbound solar radiation in atmosphere; and olivine dissolution in water, a key chemical reaction envisaged in climate engineering , aiming to reduce the amount of the carbon dioxide in extracting it from atmosphere. The SRM method works on scenarios of solar radiation decrease and the olivine dissolution method works as a carbon dioxide sequestration method. Olivine dissolution in water impacts negatively on the pH of rivers but positively in counteracting ocean acidification and in transporting the silica in ocean, which has benefits for diatom shell formation.

  9. Interplanetary Radiation and Internal Charging Environment Models for Solar Sails

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Altstatt, Richard L.; NeegaardParker, Linda

    2005-01-01

    A Solar Sail Radiation Environment (SSRE) model has been developed for defining charged particle environments over an energy range from 0.01 keV to 1 MeV for hydrogen ions, helium ions, and electrons. The SSRE model provides the free field charged particle environment required for characterizing energy deposition per unit mass, charge deposition, and dose rate dependent conductivity processes required to evaluate radiation dose and internal (bulk) charging processes in the solar sail membrane in interplanetary space. Solar wind and energetic particle measurements from instruments aboard the Ulysses spacecraft in a solar, near-polar orbit provide the particle data over a range of heliospheric latitudes used to derive the environment that can be used for radiation and charging environments for both high inclination 0.5 AU Solar Polar Imager mission and the 1.0 AU L1 solar missions. This paper describes the techniques used to model comprehensive electron, proton, and helium spectra over the range of particle energies of significance to energy and charge deposition in thin (less than 25 micrometers) solar sail materials.

  10. Trends in surface solar radiation in Spain since the 1980s: the role of the changes in the radiative effects of aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, Arturo; Mateos, David; Wild, Martin; Calbó, Josep; Antón, Manuel; Enriquez-Alonso, Aaron; Sanchez-Romero, Alex

    2014-05-01

    There is a growing interest in the study of decadal variations in surface solar radiation, although the analyses of long-term time series in some areas with major gaps in observations, such as in Spain, are still pending. In the first part of this work, a previously published surface solar radiation dataset in Spain is described (for more details, see Sanchez-Lorenzo et al., 2013) based on the longest series with ground-based records of global and diffuse solar radiation, most of them starting in the early 1980s and ending in 2012. Particular emphasis is placed upon the homogenization of this dataset in order to ensure the reliability of the trends. The linear trend in the mean annual series of global solar radiation shows a significant increase since 1981 of 4.0 Wm-2 (or 2.4 %) per decade. These results are in line with the increase of global solar radiation (i.e. brightening period) reported at many worldwide observation sites (Wild, 2009). In addition, the annual mean diffuse solar radiation series shows a significant decrease during the last three decades, but it is disturbed by strong increases in 1983 and 1991-1992, which might reflect the effects of the El Chichón and Pinatubo volcanic eruptions as a result of enhanced scattering of the aerosols emitted during these large volcanic eruptions. As clouds and aerosols are the main sources of uncertainty in the determination of the energy balance of the Earth, there is a growing interest in the evaluation of their radiative effects and their impact on the decadal variability of the surface solar radiation. Hence, in the second part of this work, the changes of the combined radiative effects of clouds and aerosols in Spain since the 1980s are investigated (for more details, see Mateos et al., 2013). In particular, the global solar radiation data above mentioned and radiative transfer simulations fed with reanalysis data of ozone, water vapour and surface albedo, are used to evaluate the cloud and aerosol

  11. The Potential of Heat Collection from Solar Radiation in Asphalt Solar Collectors in Malaysia

    NASA Astrophysics Data System (ADS)

    Beddu, Salmia; Talib, Siti Hidayah Abdul; Itam, Zarina

    2016-03-01

    The implementation of asphalt solar collectors as a means of an energy source is being widely studied in recent years. Asphalt pavements are exposed to daily solar radiation, and are capable of reaching up to 70°C in temperature. The potential of harvesting energy from solar pavements as an alternative energy source in replace of non-renewable energy sources prone to depletion such as fuel is promising. In Malaysia, the sun intensity is quite high and for this reason, absorbing the heat from sun radiation, and then utilizing it in many other applications such as generating electricity could definitely be impressive. Previous researches on the different methods of studying the effect of heat absorption caused by solar radiation prove to be quite old and inaffective. More recent findings, on the otherhand, prove to be more informative. This paper focuses on determining the potential of heat collection from solar radiation in asphalt solar collectors using steel piping. The asphalt solar collector model constructed for this research was prepared in the civil engineering laboratory. The hot mixed asphalt (HMA) contains 10% bitumen mixed with 90% aggregates of the total size of asphalt. Three stainless steel pipes were embedded into the interior region of the model according to the design criteria, and then put to test. Results show that harvesting energy from asphalt solar collectors proves highly potential in Malaysia due its the hot climate.

  12. Quality control and estimation of global solar radiation in China

    SciTech Connect

    Tang, Wenjun; He, Jie; Yang, Kun; Qin, Jun

    2010-03-15

    Measurements of surface radiation in China are too sparse to meet demand for scientific research and engineering applications. Moreover, the radiation data often include erroneous and questionable values though preliminary quality-check has been done before the data release. Therefore, quality control of radiation data is often a prerequisite for using these data. In this study, a set of quality-check procedures were implemented to control the quality of the solar radiation measurements at 97 stations in China. A hybrid model for estimating global solar radiation was then evaluated against the controlled data. The results show that the model can estimate the global radiation with accuracy of MBE less than 1.5 MJ m{sup -2} and RMSE less than 2.8 MJ m{sup -2} for daily radiation and RMSE less than 2.0 MJ m{sup -2} for monthly-mean daily radiation at individual stations over most of China except at a few stations where unsatisfactory estimates were possibly caused by severe air pollution or too dense clouds. The MBE averaged over all stations are about 0.7 MJ m{sup -2} and RMSE about 2.0 MJ m{sup -2} for daily radiation and RMSE about 1.3 MJ m{sup -2} for monthly-mean daily radiation. Finally, this model was used to fill data gaps and to expand solar radiation data set using routine meteorological station data in China. This data set would substantially contribute to some radiation-related scientific studies and engineering applications in China. (author)

  13. Characterization and Performance of the Suomi-NPP VIIRS Solar Diffuser Stability Monitor

    NASA Technical Reports Server (NTRS)

    Fulbright, Jon P.; Ning, Lei; Kwofu, Chiang; Xiaoxiong, Xiong

    2012-01-01

    We describe the on-orbit characterization and performance of the Solar Diffuser Stability Monitor (SDSM) on-board Suomi-NPP/VIIRS. This description includes the observing procedure of each SDSM event, the algorithms used to generate the Solar Diffuser degradation corrective factors, and the results for the mission to date. We will also compare the performance of the VIIRS SDSM and SD to the similar components operating on the MODIS instrument on the EOS Terra and Aqua satellites

  14. Estimating shortwave solar radiation using net radiation and meteorological measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shortwave radiation has a wide variety of uses in land-atmosphere interactions research. Actual evapotranspiration estimation that involves stomatal conductance models like Jarvis and Ball-Berry require shortwave radiation to estimate photon flux density. However, in most weather stations, shortwave...

  15. 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.

  16. Global and diffuse solar irradiance modelling over north-western Europe using MAR regional climate model : validation and construction of a 30-year climatology

    NASA Astrophysics Data System (ADS)

    Beaumet, Julien; Doutreloup, Sébastien; Fettweis, Xavier; Erpicum, Michel

    2015-04-01

    Solar irradiance modelling is crucial for solar resource management, photovoltaic production forecasting and for a better integration of solar energy in the electrical grid network. For those reasons, an adapted version of the Modèle Atmospheric Regional (MAR) is being developed at the Laboratory of Climatology of the University of Liège in order to provide high quality modelling of solar radiation, wind and temperature over north-western Europe. In this new model version, the radiation scheme has been calibrated using solar irradiance in-situ measurements and CORINE Land Cover data have been assimilated in order to improve the modelling of 10 m wind speed and near-surface temperature. In this study, MAR is forced at its boundary by ERA-40 reanalysis and its horizontal resolution is 10 kilometres. Diffuse radiation is estimated using global radiation from MAR outputs and a calibrated version of Ruiz-Arias et al., (2010) sigmoid model. This study proposes to evaluate the method performance for global and diffuse radiation modelling at both the hourly and daily time scale using data from the European Solar Radiation Atlas database for the weather stations of Uccle (Belgium) and Braunschweig (Germany). After that, a 30-year climatology of global and diffuse irradiance for the 1981-2010 period over western Europe is built. The created data set is then analysed in order to highlight possible regional or seasonal trends. The validity of the results is then evaluated after comparison with trends found in in-situ data or from different studies from the literature.

  17. Influences of atmospheric conditions and air mass on the ratio of ultraviolet to total solar radiation

    SciTech Connect

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

    1990-08-01

    The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major atmospheric variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with atmospheric conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the atmospheric effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.

  18. [Simulation and validation of diffuse radiation in Qianyanzhou area, Jiangxi, China].

    PubMed

    Han Jia-yin; Li, Sheng-gong; Zhang, Lei-ming; Wen, Xue-fa; Li, Qing-kang; Wang, Hui-min

    2015-10-01

    Accurate estimation of diffuse radiation is of great significance for evaluating its effect on terrestrial ecosystem carbon exchange. Based on the observed diffuse radiation data in the meteorological observation field in mid-subtropical Qianyanzhou, Jiangxi, China from March 1, 2012 to February 28, 2013, the simulated results of five widely used diffuse radiation decomposition models (Reindl-1, Reindl-2, Reindl-3, Boland, BRL) were validated. The results indicated that, on the 30 min scale, all of the five models could well simulate the diffuse radiation of this area overall. But the effect of models decreased significantly with the rising of clearness index (kt). Especially when kt>0.75, each model was.unable to simulate diffuse radiation in the region. Regarding the simulation of seasonal change of diffuse radiation, the five models could simulate diffuse radiation well in most months. Relative deviation between simulated and observed values of yearly diffuse radiation of five models had a maximum of 7.1% (BRL), a minimum of 0.04% (Reindl-1), and an average of 3.6%. The simulated values of the five models appeared to be overestimated in the summer when radiation was strongest, temperature was highest, and precipitation was relatively low. For example, in July, the diffuse radiation was overestimated by 14.5%-28.2%, 21.2% on average. This was primarily due to the. method of estimating diffuse radiation under the condition of high kt. The uncertainty requires further evaluation in the model application. Considering the results of validation, simulation precision and the accessibility of input variables, the order of the simulation performance of five models was BRL>Reindl-3>Reindl-2>Reindl-1 >Boland. PMID:26995906

  19. Interpretation of Tadpole Structures in the Solar Radio Radiation

    NASA Astrophysics Data System (ADS)

    Mann, Gottfried; Melnik, Valentin; Rucker, Helmut; Konovalenko, Alexander

    2016-04-01

    The new spectrometer on the Ukrainian radio telescope UTR-2 allows to observe the solar radio radiation at low frequencies (10-30 MHz) with a high spectral and temporal resolution. Tadpole structures were observed as special fine structures in the solar radio radiation. They show a fast drift (-2.13 MHz/s) in the dynamic radio spectrum. They appear as an ensemble of tadpoles drifting slowly (-8.3 kHz/s) from high to low frequencies. The tadpoles are interpreted as electron beams accelerated at shocks in the high corona.

  20. Resonant electron diffusion as a saturation process of the synchrotron maser instability. [of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kuo, S. P.

    1986-01-01

    The theory of resonant electron diffusion as an effective saturation process of the auroral kilometric radiation has been formulated. The auroral kilometric radiation is assumed to be amplified by the synchrotron maser instability that is driven by an electron distribution of the loss-cone type. The calculated intensity of the saturated radiation is found to have a significantly lower value in comparison with that caused by the quasi-linear diffusion process as an alternative saturation process. This indicates that resonant electron diffusion dominates over quasi-linear diffusion in saturating the synchrotron maser instability.

  1. Simulation of solar radiation absorption in vegetation canopies

    NASA Technical Reports Server (NTRS)

    Kimes, D. S.; Smith, J. A.

    1980-01-01

    A solar radiation canopy absorption model, including multiple scattering effects, was developed and tested for a lodgepole pine (Pinus contorta) canopy. Reflectance above the canopy, spectral transmittance to the ground layer, and geometric and spectral measurements of canopy elements were made. Relatively large differentials occurred in spectral absorption by canopy layers, especially in the photosynthetically active region, as a function of solar zenith angle. In addition, the proportion of total global irradiance absorbed by individual layers varied greatly as a function of solar zenith angle. However, absorption by the entire canopy system remained relatively constant.

  2. Radiation Belt Radial Diffusion Coefficients Derived From Ground-based and In-situ ULF Wave Measurements

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Rae, J.; Ozeke, L.; Murphy, K. R.; Milling, D. K.; Chan, A. A.; Elkington, S. R.

    2010-12-01

    Ultra Low Frequency (ULF) wave power in the Pc5 period band is thought to play an important role in the dynamics, acceleration and transport of energetic electrons in the outer radiation belt. Current estimates of radial diffusion coefficients are typically derived empirically and characterised in terms of Kp. Using the results from a statistical analysis of ground-based and in-situ electric- and magnetic field power spectral densities as a function of solar wind speed, MLT and L-shell we compile statistical representations for the transport under a diffusive approximation. Electric diffusion rates are calculated using ground-based data from the CARISMA magnetometer network and mapped into in-situ equatorial electric fields using the Ozeke et al. [2009] model. These diffusion rates are compared to those derived from the THEMIS satellites and from previously published CRRES estimates. We find an excellent comparison between the ground-based estimates and in-situ observations. Interestingly the ground-based Pc5 power spectra show evidence of mHz spectral power peaks consistent with those observed on CRRES, and consistent with a role for field line resonances in radial diffusion. We further calculate the magnetic diffusion coefficients using data from THEMIS and GOES, and compare with previous AMPTE estimates. Overall such analysis provides a wave power based method for calculating diffusive transport using observed wave fields. Future in-situ radiation belt missions such as the Canadian Space Agency Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) will enable these physics-based models to be tested and will provide an excellent complement to the single point measurements available from the satellites.

  3. Measuring Solar Radiation Incident on Earth: Solar Constant-3 (SOLCON-3)

    NASA Technical Reports Server (NTRS)

    Crommelynck, Dominique; Joukoff, Alexandre; Dewitte, Steven

    2002-01-01

    Life on Earth is possible because the climate conditions on Earth are relatively mild. One element of the climate on Earth, the temperature, is determined by the heat exchanges between the Earth and its surroundings, outer space. The heat exchanges take place in the form of electromagnetic radiation. The Earth gains energy because it absorbs solar radiation, and it loses energy because it emits thermal infrared radiation to cold space. The heat exchanges are in balance: the heat gained by the Earth through solar radiation equals the heat lost through thermal radiation. When the balance is perturbed, a temperature change and hence a climate change of the Earth will occur. One possible perturbation of the balance is the CO2 greenhouse effect: when the amount of CO2 in the atmosphere increases, this will reduce the loss of thermal infrared radiation to cold space. Earth will gain more heat and hence the temperature will rise. Another perturbation of the balance can occur through variation of the amount of energy emitted by the sun. When the sun emits more energy, this will directly cause a rise of temperature on Earth. For a long time scientists believed that the energy emitted by the sun was constant. The 'solar constant' is defined as the amount of solar energy received per unit surface at a distance of one astronomical unit (the average distance of Earth's orbit) from the sun. Accurate measurements of the variations of the solar constant have been made since 1978. From these we know that the solar constant varies approximately with the 11-year solar cycle observed in other solar phenomena, such as the occurrence of sunspots, dark spots that are sometimes visible on the solar surface. When a sunspot occurs on the sun, since the spot is dark, the radiation (light) emitted by the sun drops instantaneously. Oddly, periods of high solar activity, when a lot of sunspot numbers increase, correspond to periods when the average solar constant is high. This indicates that

  4. Nonequilibrium ionization due to thermal diffusion and mass flows. [in solar atmosphere

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, R.

    1980-01-01

    Recent calculations of diffusion coefficients are used in the continuity equation to compute ion populations of carbon in the solar transition region. Thermal diffusion causes strong departures from ionization equilibrium in the region where the temperature gradient is steepest. Mass-conserving flows are also included in our calculations. These dominate over thermal diffusion depending on the magnitude of the flows and also lead to departures from ionization equilibrium. These results have important implications for the interpretation of EUV line emission.

  5. Solar ultraviolet radiation in a changing climate

    NASA Astrophysics Data System (ADS)

    Williamson, Craig E.; Zepp, Richard G.; Lucas, Robyn M.; Madronich, Sasha; Austin, Amy T.; Ballaré, Carlos L.; Norval, Mary; Sulzberger, Barbara; Bais, Alkiviadis F.; McKenzie, Richard L.; Robinson, Sharon A.; Häder, Donat-P.; Paul, Nigel D.; Bornman, Janet F.

    2014-06-01

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex interactions between the drivers of climate change and those of stratospheric ozone depletion, and the positive and negative feedbacks among climate, ozone and ultraviolet radiation. These will result in both risks and benefits of exposure to ultraviolet radiation for the environment and human welfare. This Review synthesizes these new insights and their relevance in a world where changes in climate as well as in stratospheric ozone are altering exposure to ultraviolet radiation with largely unknown consequences for the biosphere.

  6. Distribution of ultraviolet solar radiation at Riyadh region, Saudi Arabia.

    PubMed

    Elani, U A

    2007-01-01

    The ultraviolet UV solar radiation flux is monitored over a fixed time interval to study the daily, monthly and annual variations for a nearly one decade in Riyadh. Mathematical expressions will be presented based on a comparison between theoretical and experimental values. It is believed that the present analysis of UV radiation suggest that the environmental effects led to a better understanding of UV scattering, UV reflection, ozone and clouds layers in Riyadh and other selected areas in the mid-east region.

  7. Efficiency limits for the rectification of solar radiation

    NASA Astrophysics Data System (ADS)

    Mashaal, Heylal; Gordon, Jeffrey M.

    2013-05-01

    Efficiency limits for rectifying (converting AC to DC) incoherent broadband radiation are presented, prompted by establishing a fundamental bound for solar rectennas. For an individual full-wave rectifier, the bound is 2/π. The efficiency boosts attainable with cascaded rectifiers are also derived. The derivation of the broadband limit follows from the analysis of an arbitrary number of random-phase sinusoidal signals, which is also relevant for harvesting ambient radio-frequency radiation from a discrete number of uncorrelated sources.

  8. The solar dynamic radiator with a historical perspective

    NASA Technical Reports Server (NTRS)

    Mclallin, K. L.; Fleming, M. L.; Hoehn, F. W.; Howerton, R. L.

    1988-01-01

    A historical perspective on pumped-fluid loop space radiators provides a basis for the design of the Space Station Solar Dynamic (SD) power module radiator. SD power modules, capable of generating 25 kW (electrical) each, are planned for growth in Station power requirements. The Brayton cycle SD module configuration incorporates a pumped-fluid loop radiator that must reject up to 99 kW (thermal). The thermal/hydraulic design conditions in combination with required radiator orientation and packaging envelope form a unique set of constraints as compared to previous pumped-fluid loop radiator systems. Nevertheless, past program successes have demonstrated a technology base that can be applied to the SD radiator development program to ensure a low risk, low cost system.

  9. The Solar Dynamic radiator with a historical perspective

    NASA Technical Reports Server (NTRS)

    Mclallin, K. L.; Fleming, M. L.; Hoehn, F. W.; Howerton, R.

    1988-01-01

    A historical perspective on pumped loop space radiators provides a basis for the design of the Space Station Solar Dynamic (SD) power module radiator. SD power modules, capable of generating 25 kWe each, are planned for growth Station power requirements. The Brayton (cycle) SD module configuration incorporates a pumped loop radiator that must reject up to 99 kW. The thermal/hydraulic design conditions in combination with required radiator orientation and packaging envelope form a unique set of constraints as compared to previous pumped loop radiator systems. Nevertheless, past program successes have demonstrated a technology base which can be applied to the SD radiator development program to ensure a low risk, low cost system.

  10. Diffusive transport of energetic electrons in the 2004, May 21 solar flare

    NASA Astrophysics Data System (ADS)

    Musset, Sophie; Kontar, Eduard; Vilmer, Nicole

    2016-07-01

    Solar flares are associated with efficient particle acceleration, in particular with the production of energetic electrons which are diagnosed through the X-ray and radio emissions that they produce when interacting with the solar atmosphere. Particle transport from the acceleration sites to the radiation sites remains of the challenging topic in the field of high energy solar physics and has an important impact on the interpretation of the particle emissions in the context of acceleration models. In order to address the transport of flare associated energetic electrons in the low corona, we use imaging spectroscopic observations from RHESSI of the 2004 May 21 solar flare which presents together with the usually observed HXR footpoints a well observed coronal non-thermal X-ray source. The number of X-ray emitting energetic electrons in the coronal source is compared to the number of electrons needed to produce the hard X-ray emission in the footpoints and is found twice as large. Such an excess of the number of electrons in the coronal source cannot be explained in the context of the standard model of X-ray emissions in which the dominant electron transport is collisional. In the present flare, an additional process is needed to explain how energetic electrons can be efficiently trapped in the corona. In the hypothesis of turbulent pitch-angle scattering of hard X-ray producing energetic electrons (Kontar et al, 2014), diffusive transport can indeed lead to a confinement of energetic electrons in the coronal source. Based on this assumption, we estimated for the present event the mean-free path of energetic electrons and found a value of 10^8 - 10^9 meters, much smaller than the size of the observed flaring loop itself. This implies that a diffusive transport of energetic electrons is dominant in this flare which is in good agreement with the results of a previous study based on the gyrosynchrotron emissions from the energetic electrons (Kuznetsov & Kontar, 2015).

  11. Diffusion length in CdTe by measurement of photovoltage spectra in CdS/CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Toušek, J.; Kindl, D.; Toušková, J.; Dolhov, S.; Poruba, A.

    2001-01-01

    Modified method of surface photovoltage (SPV), spectral response measurement, and constant photocurrent method (CPM) were applied to thin film CdS/CdTe solar cells with the aim of finding diffusion length of minority carriers (L) in the CdTe material. The SPV signal was theoretically calculated without constraints of absorption coefficients for the incident radiation and thickness of the sample assuming one space charge region (SCR) located on the CdS/CdTe interface. In addition to the diffusion length, the SPV is a function of the surface recombination velocity and the parameters of the SCR, which complicates the evaluation. Illuminating the back side of the solar cell (without ohmic contact) we obtain a photovoltage spectrum predominantly influenced by the diffusion length. On the other hand, the standard measurement using light penetrating from the CdS side strongly depends on the thickness of the SCR. The small signal approximation model presented here successfully explains both measured spectra and permits extraction of the diffusion length of minority carriers and thickness of the SCR in CdTe absorber. The CPM is used for determination of absorption coefficients in the CdTe layer. The absorption of this material depends on its preparation and must be known for correct evaluation of experimental data.

  12. Solar radiation measurements and their applications in climate research

    NASA Astrophysics Data System (ADS)

    Yin, Bangsheng

    Aerosols and clouds play important roles in the climate system through their radiative effects and their vital link in the hydrological cycle. Accurate measurements of aerosol and cloud optical and microphysical properties are crucial for the study of climate and climate change. This study develops/improves retrieval algorithms for aerosol single scattering albedo (SSA) and low liquid water path (LWP) cloud optical properties, evaluates a new spectrometer, and applies long-term measurements to establish climatology of aerosol and cloud optical properties. The following results were obtained. (1) The ratio of diffuse horizontal and direct normal fluxes measured from Multifilter Rotating Shadowband Radiometer (MFRSR) has been used to derive the aerosol SSA. Various issues have impacts on the accuracy of SSA retrieval, from measurements (e.g., calibration accuracy, cosine respond correction, and forward scattering correction) to input parameters and assumptions (e.g., asymmetry factor, Rayleigh scattering optical depth, and surface albedo). This study carefully analyzed these issues and extensively assessed their impacts on the retrieval accuracy. Furthermore, the retrievals of aerosol SSA from MFRSR are compared with independent measurements from co-located instruments. (2) The Thin-Cloud Rotating Shadowband Radiometer (TCRSR) has been used to derive simultaneously the cloud optical depth (COD) and cloud drop effective radius (DER), subsequently inferring the cloud liquid-water path (LWP). The evaluation of the TCRSR indicates that the error of radiometric calibration has limited impact on the cloud DER retrievals. However, the retrieval accuracy of cloud DER is sensitive to the uncertainties of background setting (e.g., aerosol loading and the existence of ice cloud) and the measured solar aureole shape. (3) A new high resolution oxygen A-band spectrometer (HABS) has been developed, which has the ability to measure both direct-beam and zenith diffuse solar radiation

  13. Solar panel thermal cycling testing by solar simulation and infrared radiation methods

    NASA Technical Reports Server (NTRS)

    Nuss, H. E.

    1980-01-01

    For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

  14. Study of diffused solar cells based on upgraded metallurgical grade silicon

    SciTech Connect

    Schlosser, V.; Seeger, K.; Wendl, K.

    1984-05-01

    Diffused solar cells were made from upgraded metallurgical silicon (UMG-Si). The influence of the diffusion temperature and time (T /SUB d/ , t /SUB d/ ) on solar cell power output is discribed by means of the minority carrier diffusion length (L), and junction current losses. Our experiments show that improvements in junction current losses by using higher process temperatures causes a decrease of L, resulting in reduced short circuit current densities. To meet both requirements low current losses as well as L>15 ..mu..m a low temperature polysilicon CVD process are discussed.

  15. Incorporating photon recycling into the analytical drift-diffusion model of high efficiency solar cells

    SciTech Connect

    Lumb, Matthew P.; Steiner, Myles A.; Geisz, John F.; Walters, Robert J.

    2014-11-21

    The analytical drift-diffusion formalism is able to accurately simulate a wide range of solar cell architectures and was recently extended to include those with back surface reflectors. However, as solar cells approach the limits of material quality, photon recycling effects become increasingly important in predicting the behavior of these cells. In particular, the minority carrier diffusion length is significantly affected by the photon recycling, with consequences for the solar cell performance. In this paper, we outline an approach to account for photon recycling in the analytical Hovel model and compare analytical model predictions to GaAs-based experimental devices operating close to the fundamental efficiency limit.

  16. Theoretical Variation of Solar Radiation in a Tropical Mountain Valley

    NASA Astrophysics Data System (ADS)

    Flórez Botero, L. Z.; Ochoa, A.; Jiménez, J. F.

    2015-12-01

    Solar radiation over the earth's surface varies in response to global factors such as the atmosphere and the relative movement of Earth around the sun, and local factors related to the earth's surface features and topography. The aim of this study is to know the effect of local factors in spatial and temporal variability of solar radiation in a tropical mountain valley in Colombia. We estimated the potential solar radiation on simplified schemes of valleys by the means of theoretical exercises with different slopes and aspects for further analysis. Despite the closeness of the studied area to the line of Ecuador where the annual variation of radiation is almost zero we detected some differences. Changes were found in solar radiation on different valley schemes in terms of hours of sunshine and total energy that reaches the surface depending on the slope, the orientation of the slopes and the diurnal variation of the solar altitude angle. Results suggest that different aspects lead changes in the annual insolation up to 4 MJ / m2 on June and a lag of about two hours in the diurnal cycle of insolation in the southeast (135°) and northwest (315°) facing peaks with the highest radiation around 8 hours after sunrise. The annual variation cycle, related to the slope, does not show major changes, but the diurnal cycle of the cells with the major slope has the lower insolation with a maximum of about one hour before the other cells. Finally, a better understanding of the real dynamics of sunshine in the Valley of Aburrá - Colombia is possible knowing the variation of the annual cycle and the diurnal cycle of insolation in a synthetic valley reliant on the different aspects and slopes allows. This represents an opportunity to improve urban planning and rural productive activities that depends directly on the availability of energy.

  17. Diffusive redistribution of water vapor in the solar nebula revisited

    NASA Technical Reports Server (NTRS)

    Sears, William D.

    1993-01-01

    Stevenson and Lunine presented a model for enhancing the abundance of solid material in the region of the solar nebula at the water condensation point. This was used to provide a means to produce a much more rapid formation of Jupiter than the standard solar nebula models. However, they underestimated the drag induced sun-ward radial drift of the planetesimals of interest. Reanalysis reveals that these particles would spread over the inner solar system and might influence the formation of the asteroids.

  18. INTERACTIONS OF SOLAR ULTRAVIOLET RADIATION AND DISSOLVED ORGANIC MATTER IN FRESHWATER AND MARINE ENVIRONMENTS

    EPA Science Inventory

    Solar radiation provides the primary driving force for the biogeochemical cycles upon which life and climate depend. Recent studies have demonstrated that the absorption of solar radiation, especially 'm the ultraviolet spectral region, results in photochemical reactions that can...

  19. Solar wind ionization temperatures inferred from the charge state composition of diffuse particle events

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

    1984-01-01

    Detailed measurements of the charge state composition of energetic heavy ions in the diffuse component are presented for the first time. Spectral characteristics and charge state measurements for 12 diffuse ion events observed upstream of the earth's bow shock are reported. One event is analyzed in order to illustrate the basic assumptions and general techniques involved in the determination of charge state composition from the data. The probable solar wind origin of the seed population of the diffuse component is used together with the charge state composition of these heavy ions to estimate the charge state composition in the concurrent solar wind, and hence to infer the equilibrium coronal temperatures associated with a variety of solar wind flows. The results are compared with predicted solar wind values.

  20. Energy-Specific Solar Radiation Data from Msg: the HELIOSAT-3 Project

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, M.

    2006-08-01

    Solar energy technologies such as photovoltaics, solar thermal power plants, passive solar heating/cooling systems and day lighting in buildings are expected to continue their very rapid growth. In this context the availability of reliable solar radiation data is of high economic value both for planning and operating these systems. HELIOSAT-3 aims the quantification of surface solar irradiance in cloud free and cloudy situations and additional energy-specific parameters as direct normal and diffuse irradiance over Europe and Africa using the enhanced capabilities of MSG. Emphasis is laid on clouds, water vapor, aerosols and ozone and their influence on surface solar irradiance. Several projects as e.g. the HELIOSAT-3 and PVSAT-2 European Commission FP5 and the ENVISOLAR (ESA Earth Observation Market Development Program) projects made profit from the data access and additional MSG product information obtained through the RAO program. The paper focuses on results obtained during the RAO project based on funding in HELIOSAT-3, PVSAT-2 and ENVISOLAR projects.

  1. Increased diffuse radiation fraction does not significantly accelerate plant growth

    NASA Astrophysics Data System (ADS)

    Angert, Alon; Krakauer, Nir

    2010-05-01

    A recent modelling study (Mercado et al., 2009) claims that increased numbers of scattering aerosols are responsible for a substantial fraction of the terrestrial carbon sink in recent decades because higher diffuse light fraction enhances plant net primary production (NPP). Here we show that observations of atmospheric CO2 seasonal cycle and tree ring data indicate that the relation between diffuse light and NPP is actually quite weak on annual timescales. The inconsistency of these data with the modelling results may arise because the relationships used to quantify the enhancement of NPP were calibrated with eddy covariance measurements of hourly carbon uptake. The effect of diffuse-light fraction on carbon uptake could depend on timescale, since this effect varies rapidly as sun angle and cloudiness change, and since plants can respond dynamically over various timescales to change in incoming radiation. Volcanic eruptions, such as the eruption of Mount Pinatubo in 1991, provide the best available tests for the effect of an annual-scale increase in the diffuse light fraction. Following the Pinatubo Eruption, in 1992 and 1993, a sharp decrease in the atmospheric CO2 growth rate was observed. This could have resulted from enhanced plant carbon uptake. Mercado et al. (2009) argue that largely as a result of the (volcanic aerosol driven) increase in diffuse light fraction, NPP was elevated in 1992, particularly between 25° N-45° N where annual NPP was modelled to be ~0.8 PgC (~10%) above average. In a previous study (Angert et al., 2004) a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH), was used to show that a diffuse-radiation driven increase in NPP in the extratropics will enhance carbon uptake mostly in summer, leading to a lower CO2 seasonal minimum. Here we use a 'toy model' to show that this conclusion is general and model-independent. The model shows that an enhanced sink of 0.8 PgC, similar to that modelled by Mercado et al. (2009

  2. Super-diffusion versus competitive advection processes on the solar surface

    NASA Astrophysics Data System (ADS)

    Del Moro, Dario; Berrilli, Francesco; Giovannelli, Luca; Scardigli, Stefano; Giannattasio, Fabio; Consolini, Giuseppe; Lepreti, Fabio

    2016-04-01

    From the analysis of the displacement spectrum of magnetic element, it has recently been agreed that a regime of super-diffusivity dominates the solar surface. Quite habitually this result is discussed in the framework of fully developed turbulence. However, the debate whether the super-diffusivity is generated by a turbulent dispersion process, by the advection due to the convective pattern, or even by another process is still open, as is the question of the amount of diffusivity at the scales relevant to the local dynamo process. To understand how such peculiar diffusion in the solar atmosphere takes place, we compared the results from two different data sets (ground-based and space-borne) and confronted those results also to simulation of passive tracers advection. The displacement spectra of the magnetic elements obtained by the data sets are consistent in retrieving a super-diffusive regime for the solar photosphere, but also the simulation shows a super-diffusive displacement spectrum: its competitive advection process can reproduce the signature of super-diffusion. Therefore, it is not necessary to hypothesize a totally developed turbulence regime to explain the motion of the magnetic elements on the solar surface.

  3. Parameterization of cloud effects on the absorption of solar radiation

    NASA Technical Reports Server (NTRS)

    Davies, R.

    1983-01-01

    A radiation parameterization for the NASA Goddard climate model was developed, tested, and implemented. Interactive and off-hire experiments with the climate model to determine the limitations of the present parameterization scheme are summarized. The parameterization of Cloud absorption in terms of solar zeith angle, column water vapors about the cloud top, and cloud liquid water content is discussed.

  4. Listing of solar radiation measuring equipment and glossary

    NASA Technical Reports Server (NTRS)

    Carter, E. A.; Greenbaum, S. A.; Patel, A. M.

    1976-01-01

    An attempt is made to list and provide all available information about solar radiation measuring equipment which are being manufactured and are available on the market. The list is in tabular form and includes sensor type, response time, cost data and comments for each model. A cost code is included which shows ranges only.

  5. RISK ASSESSMENT FOR THE EFFECTS OF SOLAR RADIATION ON AMPHIBIANS

    EPA Science Inventory

    Recent studies have demonstrated that exposure to solar ultraviolet radiation (UVR) can cause mortality and increase the occurrence of eye and limb malformation in some species of amphibians. Based on these reports and various field observations, it has been hypothesized that UV...

  6. Improved Solar-Radiation-Pressure Models for GPS Satellites

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Yoaz; Kuang, Da

    2006-01-01

    A report describes a series of computational models conceived as an improvement over prior models for determining effects of solar-radiation pressure on orbits of Global Positioning System (GPS) satellites. These models are based on fitting coefficients of Fourier functions of Sun-spacecraft- Earth angles to observed spacecraft orbital motions.

  7. Glacial Influences on Solar Radiation in a Subarctic Sea.

    EPA Science Inventory

    Understanding macroscale processes controlling solar radia­tion in marine systems will be important in interpreting the potential effects of global change from increasing ultraviolet radiation (UV) and glacial retreat. This study provides the first quantitative assessment of UV i...

  8. Progress on an Updated National Solar Radiation Data Base: Preprint

    SciTech Connect

    Wilcox, S.; Anderberg, M.; George, R.; Marion, W.; Myers, D.; Renne, D.; Beckman, W.; DeGaetano, A.; Gueymard, C.; Perez, R.; Plantico, M.; Stackhouse, P.; Vignola, F.

    2004-03-01

    In 1992, The National Renewable Energy Laboratory (NREL) released the 1961-1990 National Solar Radiation Data Base (NSRDB), a 30-year set of hourly solar radiation data. In April 2003, NREL convened a meeting of experts to investigate issues concerning a proposed update of the NSRDB. The panel determined that an important difficulty posed by the update was the shift from manual to automated cloud observations at National Weather Service stations in the United States. The solar model used in the original NSRDB relied heavily on the methodology and resolution of the manual cloud observations. The meeting participants recommended that NREL produce a plan for creating an update using currently available meteorological observations and satellite imagery. This paper describes current progress toward a plan for an updated NSRDB.

  9. The atmospheric radiation response to solar-particle-events.

    PubMed

    O'Brien, K; Sauer, H H

    2003-01-01

    High-energy solar particles, produced in association with solar flares and coronal mass ejections, occasionally bombard the earth's atmosphere. resulting in radiation intensities additional to the background cosmic radiation. Access of these particles to the earth's vicinity during times of geomagnetic disturbances are not adequately described by using static geomagnetic field models. These solar fluxes are also often distributed non uniformly in space, so that fluxes measured by satellites obtained at great distances from the earth and which sample large volumes of space around the earth cannot be used to predict fluxes locally at the earth's surface. We present here a method which uses the ground-level neutron monitor counting rates as adjoint sources of the flux in the atmosphere immediately above them to obtain solar-particle effective dose rates as a function of position over the earth's surface. We have applied this approach to the large September 29-30, 1989 ground-level event (designated GLE 42) to obtain the magnitude and distribution of the solar-particle effective dose rate from an atypically large event. The results of these calculations clearly show the effect of the softer particle spectra associated with solar particle events, as compared with galactic cosmic rays, results in a greater sensitivity to the geomagnetic field, and, unlike cosmic rays, the near-absence of a "knee" near 60 degrees geomagnetic latitude.

  10. Origin of reverse annealing in radiation-damaged silicon solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.

    1980-01-01

    The paper employs relative defect concentrations, energy levels, capture cross sections, and minority carrier diffusion lengths in order to identify the defect responsible for the reverse annealing observed in a radiation damaged n(+)/p silicon solar cell. It is reported that the responsible defect, with the energy level at +0.30 eV, has been tentatively identified as boron-oxygen-vacancy complex. In conclusion, it is shown that removal of this defect could result in significant cell recovery when annealing at temperatures well below the currently required 400 C.

  11. Treatment of Solar and Thermal Radiation in Global Climate Models

    NASA Astrophysics Data System (ADS)

    Lacis, A. A.; Oinas, V.

    2015-12-01

    It is the interaction of solar and thermal radiation with the climate system constituents that determines the prevailing climate on Earth. The principal radiative constituents of the climate system are clouds, aerosols, greenhouse gases, and the ground surface. Accurate rendering of their interaction with the incident solar radiation and the outgoing thermal radiation is required if a climate model is to be capable of simulating and predicting the complex changes that take place in the terrestrial climate system. In the GISS climate model, these radiative tasks are accomplished with a GCM radiation model that utilizes the correlated k-distribution treatment that closely matches Line-by-Line accuracy (Lacis and Oinas, 1991) for the gaseous absorbers, and an adaptation of the doubling/adding method (Lacis and Hansen, 1974) to compute multiple scattering by clouds and aerosols. The radiative parameters to model the spectral dependence of solar and longwave radiation (UV to microwave) utilizes Mie scattering and T-matrix calculations covering the broad range of particle sizes and compositions encountered in the climate system. Cloud treatment also incorporates an empirical representation of sub-grid inhomogeneity and space-time variability of cloud optical properties (derived from ISCCP data) that utilizes a Monte Carlo-based re-scaling parameterization of the cloud plane-parallel radiative parameters (Cairns et al, 2001). The longwave calculations compute correlated k-distribution radiances at three quadrature points (without scattering), and include the effects of cloud scattering in parameterized form for the outgoing and downwelling LW fluxes. For hygroscopic aerosols (e.g., sulfates, nitrates, sea salt), the effects of changing relative humidity on particle size and refractive index are explicitly taken into account. In this way, the GISS GCM radiation model calculates the SW and LW radiative fluxes, and the corresponding radiative heating and cooling rates in

  12. Solar ultraviolet radiation in a changing climate

    EPA Science Inventory

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

  13. Satellite-based surface solar radiation data provided by CM SAF - Solar energy applications

    NASA Astrophysics Data System (ADS)

    Trentmann, Jörg; Müller, Richard W.; Posselt, Rebekka; Stöckli, Reto

    2013-04-01

    The planning of solar power plants requires accurate estimates of the solar energy available at the surface. Satellite observations provide useful information on the cloud coverage, which is one of the main factors modulating the solar surface radiation. This information can be used to estimate the solar surface radiation from satellite. Observations from geostationary satellites allow the retrieval of the surface solar radiation with high temporal (up to hourly) and spatial (approx. 5 km) resolution. The EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF) is deriving surface solar radiation from geostationary and polar-orbiting satellite instruments. While CM SAF is focusing on the generation of high-quality long-term climate data records, also operationally data is provided in short time latency within 8 weeks. CM SAF has already released one data set based on geostationary Meteosat satellite covering 1983 to 2005 (doi: 10.5676/EUM_SAF_CM/RAD_MVIRI/V001) and one global data set based on measurements of the polar-orbiting AVHRR instruments covering 1982 to 2009 (doi: 10.5676/EUM_SAF_CM/CLARA_AVHRR/V001). Here, we present details and applications of the CM SAF surface radiation data generated from the observations of the geostationary Meteosat satellites. The climate data set is available at high spatial (0.03 x 0.03 deg) and temporal (hourly, daily, monthly) resolutions. Besides global radiation, also the direct beam component is provided, which is for instance required for the estimation of the energy generated by solar thermal plants. Based on comparisons with surface observations the accuracy of CM SAF surface solar radiation data is better than 10 W/m2 on a monthly basis and 25 W/m2 on a daily basis. The data sets are well documented (incl. validation using surface observations) and available in netcdf-format at no cost without restrictions at www.cmsaf.eu. Solar energy applications of the data include the Photovoltaic Geographical

  14. Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora

    NASA Technical Reports Server (NTRS)

    Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R.

    2011-01-01

    The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods

  15. Effects of solar radiation on hair and photoprotection.

    PubMed

    Dario, Michelli F; Baby, André R; Velasco, Maria Valéria R

    2015-12-01

    In this paper the negative effects of solar radiation (ultraviolet, visible and infrared wavelengths) on hair properties like color, mechanical properties, luster, protein content, surface roughness, among others, will be discussed. Despite knowing that radiation damages hair, there are no consensus about the particular effect of each segment of solar radiation on the hair shaft. The hair photoprotection products are primarily targeted to dyed hair, specially auburn pigments, and gray shades. They are usually based on silicones, antioxidants and quaternary chemical UV filters that have more affinity for negatively charged hair surface and present higher efficacy. Unfortunately, there are no regulated parameters, like for skin photoprotection, for efficacy evaluation of hair care products, which makes impossible to compare the results published in the literature. Thus, it is important that researchers make an effort to apply experimental conditions similar to a real level of sun exposure, like dose, irradiance, time, temperature and relative humidity. PMID:26454659

  16. Radiation tolerance of boron doped dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.

    1980-01-01

    The potential of dendritic web silicon for giving radiation hard solar cells is compared with the float zone silicon material. Solar cells with n(+)-p-P(+) structure and approximately 15% (AMl) efficiency were subjected to 1 MeV electron irradiation. Radiation tolerance of web cell efficiency was found to be at least as good as that of the float zone silicon cell. A study of the annealing behavior of radiation-induced defects via deep level transient spectroscopy revealed that E sub v + 0.31 eV defect, attributed to boron-oxygen-vacancy complex, is responsible for the reverse annealing of the irradiated cells in the temperature range of 150 to 350 C.

  17. Effects of solar radiation on hair and photoprotection.

    PubMed

    Dario, Michelli F; Baby, André R; Velasco, Maria Valéria R

    2015-12-01

    In this paper the negative effects of solar radiation (ultraviolet, visible and infrared wavelengths) on hair properties like color, mechanical properties, luster, protein content, surface roughness, among others, will be discussed. Despite knowing that radiation damages hair, there are no consensus about the particular effect of each segment of solar radiation on the hair shaft. The hair photoprotection products are primarily targeted to dyed hair, specially auburn pigments, and gray shades. They are usually based on silicones, antioxidants and quaternary chemical UV filters that have more affinity for negatively charged hair surface and present higher efficacy. Unfortunately, there are no regulated parameters, like for skin photoprotection, for efficacy evaluation of hair care products, which makes impossible to compare the results published in the literature. Thus, it is important that researchers make an effort to apply experimental conditions similar to a real level of sun exposure, like dose, irradiance, time, temperature and relative humidity.

  18. Study of radiatively sustained cesium plasmas for solar energy conversion

    NASA Technical Reports Server (NTRS)

    Palmer, A. J.; Dunning, G. J.

    1980-01-01

    The results of a study aimed at developing a high temperature solar electric converter are reported. The converter concept is based on the use of an alkali plasma to serve as both an efficient high temperature collector of solar radiation as well as the working fluid for a high temperature working cycle. The working cycle is a simple magnetohydrodynamic (MHD) Rankine cycle employing a solid electrode Faraday MHD channel. Research milestones include the construction of a theoretical model for coupling sunlight in a cesium plasma and the experimental demonstration of cesium plasma heating with a solar simulator in excellent agreement with the theory. Analysis of a solar MHD working cycle in which excimer laser power rather than electric power is extracted is also presented. The analysis predicts a positive gain coefficient on the cesium-xenon excimer laser transition.

  19. SeaWiFS long-term solar diffuser reflectance and sensor noise analyses

    SciTech Connect

    Eplee, Robert E. Jr.; Patt, Frederick S.; Barnes, Robert A.; McClain, Charles R

    2007-02-10

    The NASA Ocean Biology Processing Group's Calibration and Validation(Cal/Val) team has undertaken an analysis of the mission-long Sea-Viewing Wide Field-of-View Sensor (SeaWiFS)solar calibration time series to assess the long-term degradation of the solar diffuser reflectance over 9 years on orbit. The SeaWiFS diffuser is an aluminum plate coated with YB71 paint. The bidirectional reflectance distribution function of the diffuser was not fully characterized before launch,so the Cal/Val team has implemented a regression of the solar incidence angles and the drift in the node of the satellite's orbit against the diffuser time series to correct for solar incidence angle effects. An exponential function with a time constant of 200 days yields the best fit to the diffuser time series.The decrease in diffuser reflectance over the mission is wavelength dependent,ranging from 9% in the blue(412 nm) to 5% in the red and near infrared(670-865 nm). The Cal/Val team has developed a methodology for computing the signal-to-noise ratio (SNR) for SeaWiFS on orbit from the diffuser time series corrected for both the varying solar incidence angles and the diffuser reflectance degradation. A sensor noise model is used to compare on-orbit SNRs computed for radiances reflected from the diffuser with prelaunch SNRs measured at typical radiances specified for the instrument. To within the uncertainties in the measurements, the SNRs for SeaWiFS have not changed over the mission. The on-orbit performance of the SeaWiFS solar diffuser should offer insight into the long-term on-orbit performance of solar diffusers on other instruments, such as the Moderate-Resolution Imaging Spectrometer [currently flying on the Earth Observing System (EOS) Terra and Aqua satellites], the Visible and Infrared Radiometer Suite [scheduled to fly on the NASA National Polar-orbiting Operational Environmental Satellite System (NPOESS) and NPOESS Preparatory Project (NPP) satellites] and the Advanced Baseline

  20. Placement and efficiency effects on radiative forcing of solar installations

    NASA Astrophysics Data System (ADS)

    Burg, Brian R.; Ruch, Patrick; Paredes, Stephan; Michel, Bruno

    2015-09-01

    The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of different solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes.

  1. Placement and efficiency effects on radiative forcing of solar installations

    SciTech Connect

    Burg, Brian R.; Ruch, Patrick; Paredes, Stephan; Michel, Bruno

    2015-09-28

    The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of different solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes.

  2. Stratospheric Response to Intraseasonal Changes in Incoming Solar Radiation

    NASA Astrophysics Data System (ADS)

    Garfinkel, Chaim; silverman, vered; harnik, nili; Erlich, caryn

    2016-04-01

    Superposed epoch analysis of meteorological reanalysis data is used to demonstrate a significant connection between intraseasonal solar variability and temperatures in the stratosphere. Decreasing solar flux leads to a cooling of the tropical upper stratosphere above 7hPa, while increasing solar flux leads to a warming of the tropical upper stratosphere above 7hPa, after a lag of approximately six to ten days. Late winter (February-March) Arctic stratospheric temperatures also change in response to changing incoming solar flux in a manner consistent with that seen on the 11 year timescale: ten to thirty days after the start of decreasing solar flux, the polar cap warms during the easterly phase of the Quasi-Biennal Oscillation. In contrast, cooling is present after decreasing solar flux during the westerly phase of the Quasi-Biennal Oscillation (though it is less robust than the warming during the easterly phase). The estimated composite mean changes in Northern Hemisphere upper stratospheric (~ 5hPa) polar temperatures exceed 8K, and are potentially a source of intraseasonal predictability for the surface. These changes in polar temperature are consistent with the changes in wave driving entering the stratosphere. Garfinkel, C.I., V. Silverman, N. Harnik, C. Erlich, Y. Riz (2015), Stratospheric Response to Intraseasonal Changes in Incoming Solar Radiation, J. Geophys. Res. Atmos., 120, 7648-7660. doi: 10.1002/2015JD023244.

  3. Galactic and solar radiation exposure to aircrew during a solar cycle.

    PubMed

    Lewis, B J; Bennett, L G I; Green, A R; McCall, M J; Ellaschuk, B; Butler, A; Pierre, M

    2002-01-01

    An on-going investigation using a tissue-equivalent proportional counter (TEPC) has been carried out to measure the ambient dose equivalent rate of the cosmic radiation exposure of aircrew during a solar cycle. A semi-empirical model has been derived from these data to allow for the interpolation of the dose rate for any global position. The model has been extended to an altitude of up to 32 km with further measurements made on board aircraft and several balloon flights. The effects of changing solar modulation during the solar cycle are characterised by correlating the dose rate data to different solar potential models. Through integration of the dose-rate function over a great circle flight path or between given waypoints, a Predictive Code for Aircrew Radiation Exposure (PCAIRE) has been further developed for estimation of the route dose from galactic cosmic radiation exposure. This estimate is provided in units of ambient dose equivalent as well as effective dose, based on E/H x (10) scaling functions as determined from transport code calculations with LUIN and FLUKA. This experimentally based treatment has also been compared with the CARI-6 and EPCARD codes that are derived solely from theoretical transport calculations. Using TEPC measurements taken aboard the International Space Station, ground based neutron monitoring, GOES satellite data and transport code analysis, an empirical model has been further proposed for estimation of aircrew exposure during solar particle events. This model has been compared to results obtained during recent solar flare events.

  4. Emission measure distribution for diffuse regions in solar active regions

    SciTech Connect

    Subramanian, Srividya; Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2014-11-01

    Our knowledge of the diffuse emission that encompasses active regions is very limited. In this paper we investigate two off-limb active regions, namely, AR 10939 and AR 10961, to probe the underlying heating mechanisms. For this purpose, we have used spectral observations from Hinode/EIS and employed the emission measure (EM) technique to obtain the thermal structure of these diffuse regions. Our results show that the characteristic EM distributions of the diffuse emission regions peak at log T = 6.25 and the coolward slopes are in the range 1.4-3.3. This suggests that both low- as well as high-frequency nanoflare heating events are at work. Our results provide additional constraints on the properties of these diffuse emission regions and their contribution to the background/foreground when active region cores are observed on-disk.

  5. Modelling of aircrew radiation exposure during solar particle events

    NASA Astrophysics Data System (ADS)

    Al Anid, Hani Khaled

    In 1990, the International Commission on Radiological Protection recognized the occupational exposure of aircrew to cosmic radiation. In Canada, a Commercial and Business Aviation Advisory Circular was issued by Transport Canada suggesting that action should be taken to manage such exposure. In anticipation of possible regulations on exposure of Canadian-based aircrew in the near future, an extensive study was carried out at the Royal Military College of Canada to measure the radiation exposure during commercial flights. The radiation exposure to aircrew is a result of a complex mixed-radiation field resulting from Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). Supernova explosions and active galactic nuclei are responsible for GCRs which consist of 90% protons, 9% alpha particles, and 1% heavy nuclei. While they have a fairly constant fluence rate, their interaction with the magnetic field of the Earth varies throughout the solar cycles, which has a period of approximately 11 years. SEPs are highly sporadic events that are associated with solar flares and coronal mass ejections. This type of exposure may be of concern to certain aircrew members, such as pregnant flight crew, for which the annual effective dose is limited to 1 mSv over the remainder of the pregnancy. The composition of SEPs is very similar to GCRs, in that they consist of mostly protons, some alpha particles and a few heavy nuclei, but with a softer energy spectrum. An additional factor when analysing SEPs is the effect of flare anisotropy. This refers to the way charged particles are transported through the Earth's magnetosphere in an anisotropic fashion. Solar flares that are fairly isotropic produce a uniform radiation exposure for areas that have similar geomagnetic shielding, while highly anisotropic events produce variable exposures at different locations on the Earth. Studies of neutron monitor count rates from detectors sharing similar geomagnetic shielding properties

  6. Directional diffusion coefficients of solar protons inside and outside the bow shock.

    NASA Technical Reports Server (NTRS)

    Verzariu, P.; Krimigis, S. M.

    1973-01-01

    The directional diffusion coefficients of low-energy (greater than or equal to 0.3 MeV) solar protons inside and outside the bow shock are examined during the solar flare event of Jan. 24, 1969. The data are derived from simultaneous observations obtained by Explorer 33 inside the magnetosheath and by Explorer 35 in the interplanetary medium. Although the gross properties of the spin-averaged intensities on a diffusion-type plot appear to be the same in both media, the directional intensities show significant variations. It is shown that directional intensities of low-energy protons can be described reasonably well by anisotropic diffusion with an associated diffusion coefficient. Directional diffusion coefficients are found to differ by a factor of as much as three among different directions in space, and from the spin-averaged diffusion coefficient. This suggests that anisotropic diffusion does indeed take place and that so called 'isotropic' diffusion coefficients derived in the past from spin-averaged intensities may actually be directional diffusion coefficients in cases where substantial anisotropies (greater than 50%) exist.

  7. Habitat Design Considerations for Implementing Solar Particle Event Radiation Protection

    NASA Technical Reports Server (NTRS)

    Simon, Mathew A.; Clowdsley, Martha S.; Walker, Steven A.

    2013-01-01

    Radiation protection is an important habitat design consideration for human exploration missions beyond Low Earth Orbit. Fortunately, radiation shelter concepts can effectively reduce astronaut exposure for the relatively low proton energies of solar particle events, enabling moderate duration missions of several months before astronaut exposure (galactic cosmic ray and solar particle event) approaches radiation exposure limits. In order to minimize habitat mass for increasingly challenging missions, design of radiation shelters must minimize dedicated, single-purpose shielding mass by leveraging the design and placement of habitat subsystems, accommodations, and consumables. NASA's Advanced Exploration Systems RadWorks Storm Shelter Team has recently designed and performed radiation analysis on several low dedicated mass shelter concepts for a year-long mission. This paper describes habitat design considerations identified during the study's radiation analysis. These considerations include placement of the shelter within a habitat for improved protection, integration of human factors guidance for sizing shelters, identification of potential opportunities for habitat subsystems to compromise on individual subsystem performances for overall vehicle mass reductions, and pre-configuration of shelter components for reduced deployment times.

  8. Photodegradation effects in materials exposed to high flux solar and solar simulated radiation

    SciTech Connect

    Ignatiev, A.

    1992-04-01

    This report contains study results about photodegradation effects in materials exposed to high flux solar and solar simulated radiation. The studies show that high flux photoirradiation of materials can result in significant changes in the stability of materials. Photodesorption and photo-enhanced oxidation were determined to be the major mechanisms. These mechanisms were shown to affect, in extremely adverse ways, the expected thermal stability of solar relevant materials, especially stainless steels, (It is expected that related high temperature alloy steels will be similarly affected.) An analytical expression was generated to predict the flux behavior of the steels using {number_sign}304 as a prototypical stainless steel system.

  9. Radiation Testing of PICA at the Solar Power Tower

    NASA Technical Reports Server (NTRS)

    White, Susan

    2010-01-01

    Sandia National Laboratory's Solar Power Tower was used to irradiate specimens of Phenolic Impregnated Carbon Ablator (PICA), in order to evaluate whether this thermal protection system material responded differently to potential shock layer radiative heating than to convective heating. Tests were run at 50, 100 and 150 Watts per square centimeter levels of concentrated solar radiation. Experimental results are presented both from spectral measurements on 1- 10 mm thick specimens of PICA, as well as from in-depth temperature measurements on instrumented thicker test specimens. Both spectral measurements and measured in-depth temperature profiles showed that, although it is a porous, low-density material, PICA does not exhibit problematic transparency to the tested high levels of NIR radiation, for all pragmatic cm-to-inch scale thicknesses. PICA acted as a surface absorber to efficiently absorb the incident visible and near infrared incident radiation in the top 2 millimeter layer in the Solar Power Tower tests up to 150 Watts per square centimeter.

  10. Acceleration and Radiation Model of Particles in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Anastasios; Dauphin, Cyril; Vilmer, Nicole

    2006-08-01

    Cellular Automata (CA) models have successfully reproduced several statistical properties of solar flares such as the peak flux or the total flux distribution. We are using a CA model based on the concept of self organized criticality (SOC) to model the evolution of the magnetic energy released in a solar flare. Each burst of magnetic energy released is assumed to be the consequence of a magnetic reconnection process, where the particles are accelerated by a direct electric field. We relate the difference of energy gain of particles (alpha particles, protons and electrons) to the magnetic energy released and we calculate the resulting kinetic energy distributions and the emitted radiation.

  11. Radiation response of n-type base InP solar cells

    NASA Astrophysics Data System (ADS)

    Walters, Robert J.; Messenger, S. R.; Summers, G. P.; Romero, M. J.; Al-Jassim, M. M.; Araújo, D.; Garcia, R.

    2001-10-01

    The effects of particle irradiation on the electrical properties of high efficiency p/n InP solar cells have been studied using a variety of techniques including current-voltage and spectral quantum efficiency measurements (QE), electron beam induced currents (EBIC), and deep level transient spectroscopy. A detailed analysis of the radiation response of the solar cell photovoltaic response is presented, and the primary damage mechanisms are identified. Data measured after irradiation by protons of various energies are correlated in terms of displacement damage dose to produce a characteristic degradation curve for the p/n InP technology. This characteristic curve is compared to that of the n/p InP technology to provide an assessment of the relative radiation hardness of the p/n devices. Radiation-induced decreases in the minority carrier diffusion length in both the p-type emitter and n-type base at low damage levels have been extracted from the QE and EBIC measurements, and damage coefficients have been determined. At high damage levels, EBIC profiles suggest that the primary device degradation mechanism is an increase in bulk resistivity due to electron trapping in the base. However, capacitance-voltage measurements did not indicate any change in the junction capacitance. A model to account for these effects based on radiation-induced defect kinetics is presented.

  12. MODELING THE DYNAMICAL COUPLING OF SOLAR CONVECTION WITH THE RADIATIVE INTERIOR

    SciTech Connect

    Brun, Allan Sacha; Toomre, Juri

    2011-12-01

    The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.

  13. Modeling the Dynamical Coupling of Solar Convection with the Radiative Interior

    NASA Astrophysics Data System (ADS)

    Brun, Allan Sacha; Miesch, Mark S.; Toomre, Juri

    2011-12-01

    The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.

  14. Radiation enhanced diffusion of cesium, strontium, and europium in silicon carbide

    NASA Astrophysics Data System (ADS)

    Dwaraknath, S. S.; Was, G. S.

    2016-06-01

    The radiation enhanced diffusion (RED) of three key fission products in SiC: cesium, europium, and strontium was investigated following ion irradiation at a damage rate of 4.6 × 10-4 dpa s-1 at temperatures between 900° C and 1100° C. The radiation enhancement of diffusion was as large as 107 at 900° C, and dropped to a value of 1 by 1300° C for all but cesium grain boundary diffusion. Strontium and cesium exhibited several orders of magnitude enhancement for both mechanisms. Europium enhancement was greatest at 900° C, but dropped to the thermal rates at 1100° C for both mechanisms. The trends in the RED mechanism correlated well with the point defect concentrations suggesting that both carbon and silicon vacancy concentrations are important for fission product diffusion. These constitute the first radiation-enhanced diffusion measurements of strontium, cesium and europium in SiC.

  15. Reflection of solar radiation by a cylindrical cloud

    NASA Technical Reports Server (NTRS)

    Smith, G. L.

    1989-01-01

    Potential applications of an analytic method for computing the solar radiation reflected by a cylindrical cloud are discussed, including studies of radiative transfer within finite clouds and evaluations of these effects on other clouds and on remote sensing problems involving finite clouds. The pattern of reflected sunlight from a cylindrical cloud as seen at a large distance has been considered and described by the bidirectional function method for finite cloud analysis, as previously studied theoretically for plane-parallel atmospheres by McKee and Cox (1974); Schmetz and Raschke (1981); and Stuhlmann et al. (1985). However, the lack of three-dimensional radiative transfer solutions for anisotropic scattering media have hampered theoretical investigations of bidirectional functions for finite clouds. The present approach permits expression of the directional variation of the radiation field as a spherical harmonic series to any desired degree and order.

  16. Global warming due to increasing absorbed solar radiation

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Fasullo, John T.

    2009-04-01

    Global climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) are examined for the top-of-atmosphere radiation changes as carbon dioxide and other greenhouse gases build up from 1950 to 2100. There is an increase in net radiation absorbed, but not in ways commonly assumed. While there is a large increase in the greenhouse effect from increasing greenhouse gases and water vapor (as a feedback), this is offset to a large degree by a decreasing greenhouse effect from reducing cloud cover and increasing radiative emissions from higher temperatures. Instead the main warming from an energy budget standpoint comes from increases in absorbed solar radiation that stem directly from the decreasing cloud amounts. These findings underscore the need to ascertain the credibility of the model changes, especially insofar as changes in clouds are concerned.

  17. SOLAR Ultraviolet Radiation AND Vitamin D

    PubMed Central

    Rajakumar, Kumaravel; Greenspan, Susan L.; Thomas, Stephen B.; Holick, Michael F.

    2007-01-01

    Rickets, the state of vitamin D deficiency, has reemerged as a potential problem in the United States. At the dawn of the 20th century, rickets was pervasive among infants residing in the polluted cities of Europe and the northeastern United States. Important milestones in the history of rickets were the understanding that photosynthesized vitamin D and dietary vitamin D were similar, the discernment of the antirachitic potency of artificial and natural ultraviolet rays, and the discovery that ultraviolet irradiation could render various foods antirachitic. Clinical guidelines were instituted to promote sensible exposure to sunlight and artificial ultraviolet radiation. In addition, irradiated ergosterol from yeast became the major vitamin D source for food fortification and the treatment of rickets, leading to a public health campaign to eradicate rickets by the 1930s. We review the sequence and turn of events pertaining to the discovery of vitamin D and the strategies for the eradication of the reemerging rickets problem. PMID:17761571

  18. Electron Radiation Effects on Candidate Solar Sail Material

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Hollerman, William A.; Hubbs, Whitney S.; Gray, Perry A.; Wertz, George E.; Hoppe, David T.; Nehls, Mary K.; Semmel, Charles L.

    2003-01-01

    Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Solar sails are not limited by reaction mass and provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this propulsion method would need to deploy a thin sail that could be as large as many kilometers in extent. The availability of strong, ultra lightweight, and radiation resistant materials will determine the future of solar sailing. The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra lightweight materials for spacecraft propulsion. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to space environmental effects. This paper will describe the irradiation of candidate solar sail materials to energetic electrons, in vacuum, to determine the hardness of several candidate sail materials.

  19. Soot formation and radiation in turbulent jet diffusion flames under normal and reduced gravity conditions

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, LI; Sun, Jun; Greenberg, Paul S.; Griffin, Devon W.

    1993-01-01

    Most practical combustion processes, as well as fires and explosions, exhibit some characteristics of turbulent diffusion flames. For hydrocarbon fuels, the presence of soot particles significantly increases the level of radiative heat transfer from flames. In some cases, flame radiation can reach up to 75 percent of the heat release by combustion. Laminar diffusion flame results show that radiation becomes stronger under reduced gravity conditions. Therefore, detailed soot formation and radiation must be included in the flame structure analysis. A study of sooting turbulent diffusion flames under reduced-gravity conditions will not only provide necessary information for such practical issues as spacecraft fire safety, but also develop better understanding of fundamentals for diffusion combustion. In this paper, a summary of the work to date and of future plans is reported.

  20. RADIATING CURRENT SHEETS IN THE SOLAR CHROMOSPHERE

    SciTech Connect

    Goodman, Michael L.; Judge, Philip G. E-mail: judge@ucar.edu

    2012-05-20

    An MHD model of a hydrogen plasma with flow, an energy equation, NLTE ionization and radiative cooling, and an Ohm's law with anisotropic electrical conduction and thermoelectric effects is used to self-consistently generate atmospheric layers over a 50 km height range. A subset of these solutions contains current sheets and has properties similar to those of the lower and middle chromosphere. The magnetic field profiles are found to be close to Harris sheet profiles, with maximum field strengths {approx}25-150 G. The radiative flux F{sub R} emitted by individual sheets is {approx}4.9 Multiplication-Sign 10{sup 5}-4.5 Multiplication-Sign 10{sup 6} erg cm{sup -2} s{sup -1}, to be compared with the observed chromospheric emission rate of {approx}10{sup 7} erg cm{sup -2} s{sup -1}. Essentially all emission is from regions with thicknesses {approx}0.5-13 km containing the neutral sheet. About half of F{sub R} comes from sub-regions with thicknesses 10 times smaller. A resolution {approx}< 5-130 m is needed to resolve the properties of the sheets. The sheets have total H densities {approx}10{sup 13}-10{sup 15} cm{sup -3}. The ionization fraction in the sheets is {approx}2-20 times larger, and the temperature is {approx}2000-3000 K higher than in the surrounding plasma. The Joule heating flux F{sub J} exceeds F{sub R} by {approx}4%-34%, the difference being balanced in the energy equation mainly by a negative compressive heating flux. Proton Pedersen current dissipation generates {approx}62%-77% of the positive contribution to F{sub J} . The remainder of this contribution is due to electron current dissipation near the neutral sheet where the plasma is weakly magnetized.

  1. Turbulent diffusion on the solar photosphere through 24-hour continuous observations of magnetic elements

    NASA Astrophysics Data System (ADS)

    Giannattasio, F.; Berrilli, F.; Del Moro, D.; Bellot Rubio, L.; Orozco Suarez, D.; Gosic, M.

    2012-12-01

    Solar atmosphere is a unique laboratory for the study of turbulent flows under extreme conditions (e.g. very high Reynolds numbers). The turbulent nature of the flow may be approached by determining how magnetic flux elements are transported on the solar surface, and measuring the spatio-temporal scales on which these small magnetic structures are organized. The process involved is diffusion. Several works explored this topic, both by simulations and observations, and the results are often contradictory, ranging from fully-developed turbulent scenarios to normal-diffusive motions. We analyze 24-hour continuous Hinode SOT observations of a supergranular region (for the first time these long scales are explored), studying the evolution of the mutual distance between magnetic element pairs and its scaling laws, in order to investigate the diffusion process. We find a super-diffusive behavior, with a gamma index depending on the spatial scale selected.

  2. 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.

  3. Modelling of radiation exposure at high altitudes during solar storms.

    PubMed

    Al Anid, H; Lewis, B J; Bennett, L G I; Takada, M

    2009-10-01

    A transport code analysis using Monte Carlo N-Particle eXtended code, MCNPX, has been used to propagate an extrapolated particle spectrum based on satellite measurements through the atmosphere to estimate radiation exposure during solar storms at high altitudes. Neutron monitor count rate data from stations around the world were used to benchmark the model calculations during a ground-level event (GLE). A comparison was made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during GLE 60. A computer code has been developed to implement the model for routine analysis.

  4. Bounds for the rectification efficiency of solar radiation

    NASA Astrophysics Data System (ADS)

    Mashaal, Heylal; Gordon, Jeffrey M.

    2013-09-01

    Efficiency bounds for the rectification (AC to DC conversion) efficiency of non-coherent broadband radiation are derived, motivated by determining a basic limit for solar rectifying antennas. The limit is shown to be 2/π for a single full-wave rectifier. We also derive the increase in rectification efficiency that is possible by cascading multiple rectifiers. The approach for deriving the broadband limit follows from an analysis of sinusoidal signals of random phase. This analysis is also germane for harvesting ambient radio-frequency radiation from multiple uncorrelated sources.

  5. Progress in p(+)n InP solar cells fabricated by thermal diffusion

    NASA Technical Reports Server (NTRS)

    Faur, Mircea; Faur, Maria; Flood, D. J.; Brinker, D. J.; Weinberg, I.; Fatemi, N. S.; Vargas-Aburto, Carlos; Goradia, C.; Goradia, Manju

    1992-01-01

    In SPRAT XI, we proposed that p(sup +)n diffused junction InP solar cells should exhibit a higher conversion efficiency than their n(sup +)p counterparts. This was mainly due to the fact that our p(sup +)n (Cd,S) cell structures consistently showed higher V (sub OC) values than our n(sup +)p (S,Cd) structures. The highest V(sub OC) obtained with the p(sup +)n (Cd,S) cell configuration was 860 mV, as compared to the highest V(sub OC) 840 mV obtained with the n(sup +)p (S,Cd) configuration (AMO, 25 C). In this work, we present the performance results of our most recent thermally diffused cells using the p(sup +)n (Cd,S) structure. We have been able to fabricate cells with V(sub OC) values approaching 880 mV. Our best cell with an unoptimized front contact grid design (GS greater than or equal to 10%) showed a conversion efficiency of 13.4% (AMO, 25 C) without an AR coating layer. The emitter surface was passivated by a -50A P rich oxide. Achievement of such high V(sub OC) values was primarily due to the fabrication of emitter surfaces, having EPD densities as low as 2E2 cm(sup -2) and N(sub a)N(sub d) of about 3E18 cm (sup -3). In addition, our preliminary investigation of p(sup +)n structures seem to suggest that Cd-doped emitter cells are more radiation resistant than Zn-doped emitter cells against both high energy electron and proton irradiation.

  6. Radiometric calibration of a 100 cm sphere integrating source for VIIRS solar diffuser stability monitor bands

    NASA Astrophysics Data System (ADS)

    Kim, Eugene D.; Murgai, Vijay; Menzel, Reinhard W.

    2012-09-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Joint Polar-orbiting Satellite System (JPSS) mission has a solar diffuser as a reflective band calibrator. Due to UV solarization of the solar diffuser, the Solar Diffuser Stability Monitor (SDSM) is on-board to track the reflectance change of the solar diffuser in visible to near IR wavelengths. A 100 cm Sphere Integrating Source (SIS) has been used to configure and test the SDSM on the ground since MODerate resolution Imaging Spectroradiometer (MODIS) programs. Recent upgrades of the radiance transfer and BRDF measurement instruments in Raytheon have enabled more spectral data and faster measurement time with comparable uncertainty to the previous methods. The SIS has a Radiance Monitor, which has been mainly used as a SIS real-time health checker. It has been observed that the Radiance Monitor response is sufficiently linear and stable thus the Radiance Monitor can be used as a calibrator for ground tests. This paper describes the upgraded SIS calibration instruments, and the changes in the calibration philosophy of the SIS for the SDSM bands.

  7. Data From HANE-Generated Radiation Belts and the Origin of Diffusion Theory

    SciTech Connect

    Winske, Dan

    2012-07-16

    In this presentation we briefly review some of the published data regarding the artificial radiation belts produced by the Starfish and R2 high altitude nuclear explosions in 1962. The data showed slow temporal variations of the belts in altitude (L) and pitch angle ({alpha}) that could be modeled as a diffusion process. That early work formed the basis for more complex radiation belt diffusion models that are in use at present.

  8. [Solar activity, dynamics of the ozone layer and possible role of ultraviolet radiation in heliobiology].

    PubMed

    Vladimirskiĭ, B M

    1982-01-01

    Solar activity influences the ozonosphere thickness, thus changing the intensity of the near-Earth ultraviolet radiation in the B band. In certain regions the radiation may change by 10--15%, with solar activity varying from its maximum to minimum. The variations in the ultraviolet intensity are very likely to be environmentally important. Thus, solar ultraviolet radiation at lambda = 290 -- 340 nm acts as one more physical agent transferring the effect of solar activity into the biosphere.

  9. Solar Radiation and Cloud Radiative Forcing in the Pacific Warm Pool Estimated Using TOGA COARE Measurements

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Chou, Shu-Hsien; Zhao, Wenzhong

    1999-01-01

    The energy budget of the tropical western Pacific (TWP) is particularly important because this is one of the most energetic convection regions on the Earth. Nearly half of the solar radiation incident at the top of atmosphere is absorbed at the surface and only about 22% absorbed in the atmosphere. A large portion of the excess heat absorbed at the surface is transferred to the atmosphere through evaporation, which provides energy and water for convection and precipitation. The western equatorial Pacific is characterized by the highest sea surface temperature (SST) and heaviest rainfall in the world ocean. A small variation of SST associated with the eastward shift of the warm pool during El-Nino/Souther Oscillation changes the atmospheric circulation pattern and affects the global climate. In a study of the TWP surface heat and momentum fluxes during the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) Intensive observing period (IOP) from November 1992 to February have found that the solar radiation is the most important component of the surface energy budget, which undergoes significant temporal and spatial variation. The variations are influenced by the two 40-50 days Madden Julian Oscillations (MJOs) which propagated eastward from the Indian Ocean to the Central Pacific during the IOP. The TWP surface solar radiation during the COARE IOP was investigated by a number of studies. In addition, the effects of clouds on the solar heating of the atmosphere in the TWP was studied using energy budget analysis. In this study, we present some results of the TWP surface solar shortwave or SW radiation budget and the effect of clouds on the atmospheric solar heating using the surface radiation measurements and Japan's Geostationary Meteorological Satellite 4 radiance measurements during COARE IOP.

  10. Radiation energy receiver for laser and solar propulsion systems

    NASA Technical Reports Server (NTRS)

    Rault, D. F. G.; Hertzberg, A.

    1983-01-01

    The concept of remotely heating a rocket propellant with a high intensity radiant energy flux is especially attractive due to its high specific impulse and large payload mass capabilities. In this paper, a radiation receiver-thruster which is especially suited to the particular thermodynamic and spectral characteristics of highly concentrated solar energy is proposed. In this receiver, radiant energy is volumetrically absorbed within a hydrogen gas seeded with alkali metal vapors. The alkali atoms and molecules absorb the radiant flux and, subsequently, transfer their internal excitation to hydrogen molecules through collisional quenching. It is shown that such a radiation receiver would outperform a blackbody cavity type receiver in both efficiency and maximum operating temperatures. A solar rocket equipped with such a receiver-thruster would deliver thrusts of several hundred newtons at a specific impulse of 1000 seconds.

  11. Mutagenic effects of solar UV-radiation on DNA

    NASA Astrophysics Data System (ADS)

    Rabbow, E.; Horneck, G.

    2001-08-01

    A decrease of the stratospheric ozone layer will result in an increase of shorter wavelengths of the solar radiation reaching in earth. To investigate the biological efficiency, especially the mutagenic specificity, of ranges of polychromatic UVA and UBV irradiations with wavelengths between 280 nm and 400 nm, the plasmid DNA pUC19 and its E. coli host strain JM83 were used as a model system. Different ranges of solar UV radiation were simulated with the SOL 2 sun simulator (Dr. Hönle) and a variety of cut-off filters (Schott). Three wavelength bands were investigated: 280 - 400 nm (simulating UV-range under a stratospheric ozone layer depletion), 300-400 nm (simulating the UV-range today) and 315-400 nm to examine the effects induced by UVA alone.

  12. Instrumentation for remote sensing solar radiation from light aircraft.

    PubMed

    Howard, J A; Barton, I J

    1973-10-01

    The paper outlines the instrumentation needed to study, from a light aircraft, the solar radiation reflected by ground surfaces and the incoming solar radiation. A global shortwave radiometer was mounted on the roof of the aircraft and a specially designed mount was used to support a downward pointing 70-mm aerial camera, a downward pointing narrow-beam pyranometer, and, sometimes, a downward pointing global shortwave pyranometer. Calibration factors were determined for the three pyranometers by comparison with a standard Angstrom compensation pyrheliometer. Results have indicated trends in the albedos of major plant communities and have shown that the calculated albedo values vary according to whether the downward pointing instrument is narrow-beam or global. Comparisons were also made with albedos measured on the ground.

  13. Prediction of aircrew radiation exposure during solar particle events

    NASA Astrophysics Data System (ADS)

    Bennett, Les

    A transport code analysis using the Monte Carlo code MCNPX is used to propagate an extrapolated particle spectrum based on GOES satellite measurements through the atmosphere to estimate aircrew radiation exposure for solar particle events. Comparison between code predictions and actual flight measurements made during ground level event (GLE) 60 and 65 are presented. Data from ground-level neutron monitoring stations around the world are also compared against the model predictions for various events. A computer code has been further developed implementing this methodology for routine aircrew exposure estimation from solar particle events to supplement those predictions from galactic cosmic radiation using the PCAIRE code in order to better determine the overall aircrew exposure at altitude.

  14. Solar ultraviolet radiation response of EBT2 Gafchromic, radiochromic film.

    PubMed

    Butson, Ethan T; Yu, Peter K N; Butson, Martin J

    2013-11-01

    Measurement of solar ultraviolet (UV) radiation is an important aspect of dosimetry for the improved knowledge of UV exposure and its associated health related issues. EBT2 Gafchromic film has been designed by its manufacturers as an improved tool for ionizing radiation dosimetry. The film is stated as exhibiting a significant reduction in UV response. However, results have shown that when exposed to UV from the 'bottom side' i.e. from the thick laminate side, the film exhibits a sensitivity to solar UV radiation which is both measurable and accurate for UV dosimetry. Films were irradiated in this position to known solar UV exposures and results are quantified showing a reproducibility of measurement to within ±7% (1 SD) when compared to calibrated UV meters. With an exposure of 20 J cm(-2) broad spectrum solar UV, the films net OD change was found to be 0.248 OD ± 0.021 OD when analysing the results using the red channel region of an Epson V700 desktop scanner. This was compared to 0.0294 OD ± 0.0053 OD change with exposure to the same UV exposure from the top side. This means that solar UV dosimetry can be performed using EBT2 Gafchromic film utilizing the underside of the film for dosimetry. The main advantages of this film type for measurement of UV exposure is the visible colour change and thus easy analysis using a desktop scanner as well as its uniformity in response and its robust physical strength for use in outside exposure situations. PMID:24113466

  15. Visual-SOLAR: Modeling and Visualization of Solar Radiation Potential on Individual Building Rooftops

    2013-05-01

    We have developed a modeling framework for estimating solar radiation potentials on individual building rooftops that is suitable for utility-scale applications as well as building-specific applications. The framework uses light detection and ranging (LIDAR) data at approximately 1-meter horizontal resolution and 0.3-meter vertical resolution as input for modeling a large number of buildings quickly. One of the strengths of this framework is the ability to parallelize its implementation. Furthermore, the framework accounts for building specificmore » characteristics, such as roof slope, roof aspect, and shadowing effects, that are critical to roof-mounted photovoltaic system. The resulting data has helped us to identify the so-called "solar panel sweet spots" on individual building rooftops and obtain accurate statistics of the variation in solar radiation as a function of time of year and geographical location.« less

  16. Visual-SOLAR: Modeling and Visualization of Solar Radiation Potential on Individual Building Rooftops

    SciTech Connect

    2013-05-01

    We have developed a modeling framework for estimating solar radiation potentials on individual building rooftops that is suitable for utility-scale applications as well as building-specific applications. The framework uses light detection and ranging (LIDAR) data at approximately 1-meter horizontal resolution and 0.3-meter vertical resolution as input for modeling a large number of buildings quickly. One of the strengths of this framework is the ability to parallelize its implementation. Furthermore, the framework accounts for building specific characteristics, such as roof slope, roof aspect, and shadowing effects, that are critical to roof-mounted photovoltaic system. The resulting data has helped us to identify the so-called "solar panel sweet spots" on individual building rooftops and obtain accurate statistics of the variation in solar radiation as a function of time of year and geographical location.

  17. A multigrid Newton-Krylov method for flux-limited radiation diffusion

    SciTech Connect

    Rider, W.J.; Knoll, D.A.; Olson, G.L.

    1998-09-01

    The authors focus on the integration of radiation diffusion including flux-limited diffusion coefficients. The nonlinear integration is accomplished with a Newton-Krylov method preconditioned with a multigrid Picard linearization of the governing equations. They investigate the efficiency of the linear and nonlinear iterative techniques.

  18. Transmission of solar ultraviolet radiation through invertebrate exteriors

    SciTech Connect

    Karentz, D.; Gast, T. )

    1993-01-01

    The occurrence of springtime ozone depletion over the Antarctic has created concern about the effects of increases ultraviolet-B on marine organisms, particularly in intertidal and subtidal populations. The first line of defense that an animal has to solar radiation exposure is its outer covering. This paper examines four species of antarctic invertebrates to determine the amount of UV protection provided by their external covering (the sea urchin, the sea star; the limpet; and the tunicate). 5 refs., 3 figs.

  19. Solar radiation: absence of air pollution trends at Mauna Loa.

    PubMed

    Ellis, H T; Pueschel, R F

    1971-05-21

    Measurements of solar radiation made at Mauna Loa, Hawaii, over a period of 13 years give no evidence that human activities affect atmospheric turbidity on a global scale. Short-term fluctuations in insolation appear to be associated with naturally produced tropospheric aerosols. The intrusion of volcanic dust into the stratosphere results in prolonged increases in atmospheric opacity due to the extended residence times of aerosols in the stratosphere. PMID:5572907

  20. The solar radiation pressure on the Mariner 9 Mars orbiter.

    NASA Technical Reports Server (NTRS)

    Georgevic, R. M.

    1973-01-01

    The refined mathematical model of the force created by the light pressure of the sun has been used to compute the solar radiation pressure force acting on the Mariner 9 (Mariner Mars 1971) spacecraft, taking into account the reflectivity characteristics of all its components. The results have been compared with values obtained from Mariner 9 observations during the cruise phase and are found to be in agreement within 0.1% of the values.

  1. Ecohydrologic role of solar radiation on landscape evolution

    NASA Astrophysics Data System (ADS)

    Yetemen, Omer; Istanbulluoglu, Erkan; Flores-Cervantes, J. Homero; Vivoni, Enrique R.; Bras, Rafael L.

    2015-02-01

    Solar radiation has a clear signature on the spatial organization of ecohydrologic fluxes, vegetation patterns and dynamics, and landscape morphology in semiarid ecosystems. Existing landscape evolution models (LEMs) do not explicitly consider spatially explicit solar radiation as model forcing. Here, we improve an existing LEM to represent coupled processes of energy, water, and sediment balance for semiarid fluvial catchments. To ground model predictions, a study site is selected in central New Mexico where hillslope aspect has a marked influence on vegetation patterns and landscape morphology. Model predictions are corroborated using limited field observations in central NM and other locations with similar conditions. We design a set of comparative LEM simulations to investigate the role of spatially explicit solar radiation on landscape ecohydro-geomorphic development under different uplift scenarios. Aspect-control and network-control are identified as the two main drivers of soil moisture and vegetation organization on the landscape. Landscape-scale and long-term implications of these short-term ecohdrologic patterns emerged in modeled landscapes. As north facing slopes (NFS) get steeper by continuing uplift they support erosion-resistant denser vegetation cover which leads to further slope steepening until erosion and uplift attains a dynamic equilibrium. Conversely, on south facing slopes (SFS), as slopes grow with uplift, increased solar radiation exposure with slope supports sparser biomass and shallower slopes. At the landscape scale, these differential erosion processes lead to asymmetric development of catchment forms, consistent with regional observations. Understanding of ecohydrogeomorphic evolution will improve to assess the impacts of past and future climates on landscape response and morphology.

  2. Modeling hydrogen diffusion for solar cell passivation and process optimization

    NASA Astrophysics Data System (ADS)

    Zhang, Yi

    A diffusion model for hydrogen (H) in crystalline silicon was established which takes into account the charged state conversion, junction field, mobile traps, and complex formation and dissociation at dopant and trap sites. Carrier exchange among the various charged species is a "fast" process compared to the diffusion process. A numerical method was developed to solve the densities of various charged species from the Poisson's equation that involves shallow-level dopants and one "negative U" impurity, e.g., H. Time domain implicit method was adopted in finite difference scheme to solve the fully coupled equations. Limiting versions of the model were applied to the problems that are of interest to photovoltaics. Simplified trap-limited model was used to describe the low temperature diffusion profiles, assuming process-induced traps, a constant bulk trap level, and trapping/detrapping mechanisms. The results of the simulation agreed with those obtained from experiments. The best fit yielded a low surface free H concentration, Cs, (˜10 14 cm-3) from high temperature extrapolated diffusivity value. In the case of ion beam hydrogenation, mobile traps needed to be considered. PAS analysis showed the existence of vacancy-type defects in implanted Si substrates. Simulation of hydrogen diffusion in p-n junction was first attempted in this work. The order of magnitude of Cs (˜10 14 cm-3) was confirmed. Simulation results showed that the preferred charged state of H is H- (H +) in n- (p-) side of the junction. The accumulation of H- (H+) species on n+ (p+) side of the n+-p (p+-n) junction was observed, which could retard the diffusion in junction. The diffusion of hydrogen through heavily doped region in a junction is trap-limited. Several popular hydrogenation techniques were evaluated by means of modeling and experimental observations. In particular, PECVD followed by RTP hydrogenation was found to be two-step process: PECVD deposition serves as a predeposition step of H

  3. Solar radiation and water vapor pressure to forecast chickenpox epidemics.

    PubMed

    Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

    2015-03-01

    The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure.

  4. Solar radiation and water vapor pressure to forecast chickenpox epidemics.

    PubMed

    Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

    2015-03-01

    The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure. PMID:25265908

  5. Effects of solar ultraviolet radiation on tropical algal communities

    SciTech Connect

    Santas, R.

    1989-01-01

    This study assessed some of the effects of solar ultraviolet (UV) radiation ion coral reef algal assemblages. The first part of the investigation was carried out under controlled laboratory conditions in the coral reef microcosm at the National Museum of Natural History in Washington, D.C., while a field counterpart was completed at the Smithsonian Institution's marine station on Grand Turk, Turks and Caicos Islands, in the eastern Caribbean. The study attempted to separate the effects of UV-A from those of UV-B. In the laboratory, algal turf assemblages exposed to simulated solar UV radiation produced 55.1% less biomass than assemblages that were not exposed to UV. Assemblages not exposed to UV were dominated by Ectocarpus rhodochondroides, whereas in the assemblage developing under high UV radiation, Enteromorpha prolifera and eventually Schizothrix calcicola dominated. Lower UV-B irradiances caused a proportional reduction in biomass production and had less pronounced effects on species composition. UV-A did not have any significant effects on either algal turf productivity or community structure. In the field, assemblages exposed to naturally occurring solar UV supported a biomass 40% lower than that of assemblages protected from UV-B exposure. Once again, UV-A did not inhibit algal turf productivity.

  6. Highly physical penumbra solar radiation pressure modeling with atmospheric effects

    NASA Astrophysics Data System (ADS)

    Robertson, Robert; Flury, Jakob; Bandikova, Tamara; Schilling, Manuel

    2015-10-01

    We present a new method for highly physical solar radiation pressure (SRP) modeling in Earth's penumbra. The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. However, we aim to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects are tabulated to significantly reduce computational cost. We present new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the high spatial and temporal variability in lower atmospheric conditions. Modeled penumbra SRP accelerations for the Gravity Recovery and Climate Experiment (GRACE) satellites are compared to the sub-nm/s2 precision GRACE accelerometer data. Comparisons to accelerometer data and a traditional penumbra SRP model illustrate the improved accuracy which our methods provide. Sensitivity analyses illustrate the significance of various atmospheric parameters and modeled effects on penumbra SRP. While this model is more complex than a traditional penumbra SRP model, we demonstrate its utility and propose that a highly physical model which considers atmospheric effects should be the basis for any simplified approach to penumbra SRP modeling.

  7. Solar UV radiation reduces the barrier function of human skin

    PubMed Central

    Biniek, Krysta; Levi, Kemal; Dauskardt, Reinhold H.

    2012-01-01

    The ubiquitous presence of solar UV radiation in human life is essential for vitamin D production but also leads to skin photoaging, damage, and malignancies. Photoaging and skin cancer have been extensively studied, but the effects of UV on the critical mechanical barrier function of the outermost layer of the epidermis, the stratum corneum (SC), are not understood. The SC is the first line of defense against environmental exposures like solar UV radiation, and its effects on UV targets within the SC and subsequent alterations in the mechanical properties and related barrier function are unclear. Alteration of the SC’s mechanical properties can lead to severe macroscopic skin damage such as chapping and cracking and associated inflammation, infection, scarring, and abnormal desquamation. Here, we show that UV exposure has dramatic effects on cell cohesion and mechanical integrity that are related to its effects on the SC’s intercellular components, including intercellular lipids and corneodesmosomes. We found that, although the keratin-controlled stiffness remained surprisingly constant with UV exposure, the intercellular strength, strain, and cohesion decreased markedly. We further show that solar UV radiation poses a double threat to skin by both increasing the biomechanical driving force for damage while simultaneously decreasing the skin’s natural ability to resist, compromising the critical barrier function of the skin. PMID:23027968

  8. Solar radiation and malignant melanoma of the skin.

    PubMed

    Houghton, A N; Viola, M V

    1981-10-01

    Several observations suggest that a majority of cases of malignant melanoma of the skin are linked to sun exposure. Evidence includes higher occurrence of melanoma on anatomic areas heavily exposed during recreation, development of melanoma more frequently in lightly pigmented persons, and correlation of melanoma incidence and mortality with proximity to the equator. The role of the sun exposure in the pathogenesis of melanoma remains unclear, however. Many cases of melanoma may be related to heavy doses of solar radiation received during recreation. Chronic sun exposure is not so clearly linked to the development of melanoma (except in the uncommon lentigo maligna variety). Sunspot cycles have been associated with changes in melanoma incidence; an excess of melanoma cases has been observed every 9 to 12 years after peak sunspot activity. These excess cases may be caused by more intense exposure to solar ultraviolet radiation during sunspot maxima, perhaps related to changes in the stratospheric ozone layer. These epidemiologic and clinical clues suggest that many cases of melanoma are related to sun exposure triggering the appearance of clinically evident melanoma. In this regard, solar radiation behaves as a cocarcinogen or promoter, rather than a dose-dependent carcinogen. These observations also suggest that other factors may be involved in the pathogenesis of melanoma, e.g., nevi, heredity, or exposure to chemical carcinogens.

  9. Solar radiation and malignant melanoma of the skin

    SciTech Connect

    Houghton, A.N.; Viola, M.V.

    1981-01-01

    Several observations suggest that a majority of cases of malignant melanoma of the skin are linked to sun exposure. Evidence includes higher occurrence of melanoma on anatomic areas heavily exposed during recreation, development of melanoma more frequently in lightly pigmented persons, and correlation of melanoma incidence and mortality with proximity to the equator. The role of the sun exposure in the pathogenesis of melanoma remains unclear, however. Many cases of melanoma may be related to heavy doses of solar radiation received during recreation. Chronic sun exposure is not so clearly linked to the development of melanoma (except in the uncommon lentigo maligna variety). Sunspot cycles have been associated with changes in melanoma incidence; an excess of melanoma cases has been observed every 9 to 12 years after peak sunspot activity. These excess cases may be caused by more intense exposure to solar ultraviolet radiation during sunspot maxima, perhaps related to changes in the stratospheric ozone layer. These epidemiologic and clinical clues suggest that many cases of melanoma are related to sun exposure triggering the appearance of clinically evident melanoma. In this regard, solar radiation behaves as a cocarcinogen or promoter, rather than a dose-dependent carcinogen. These observations also suggest that other factors may be involved in the pathogenesis of melanoma, e.g., nevi, heredity, or exposure to chemical carcinogens.

  10. Radiation response of heteroepitaxial n+p InP/Si solar cells

    NASA Astrophysics Data System (ADS)

    Walters, R. J.; Messenger, S. R.; Cotal, H. L.; Xapsos, M. A.; Wojtczuk, S. J.; Serreze, H. B.; Summers, G. P.

    1997-09-01

    The effect of 1 MeV electron and 3 MeV proton irradiation on the performance of n+p InP solar cells grown heteroepitaxially on Si (InP/Si) substrates is presented. The radiation response of the cells was characterized by a comprehensive series of measurements of current versus voltage (I-V), capacitance versus voltage (C-V), quantum efficiency (QE), and deep level transient spectroscopy (DLTS). The degradation of the photovoltaic response of the cells, measured under simulated 1 sun, AM0 solar illumination, is analyzed in terms of displacement damage dose (Dd) which enables a characteristic degradation curve to be determined. This curve is used to accurately predict measured cell degradation under proton irradiation with energies from 4.5 down to 1 MeV. From the QE measurements, the base minority carrier diffusion length is determined as a function of particle fluence, and a diffusion length damage coefficient is calculated. From the C-V measurements, the radiation-induced carrier removal rate in the base region of the cells is determined. The DLTS data show the electron and proton irradiations to produce essentially the same defect spectra, and the spectra are essentially the same as observed in irradiated homoepitaxial n+p InP. From the DLTS data, the introduction rate of each defect level is determined. From the dark I-V curves, the effect of irradiation on the various contributions to the dark current are determined. The data are analyzed, and a detailed description of the physical mechanisms for the radiation response of these cells is given. The results enable a model to be developed for the radiation response of the cells.

  11. The measurement and analysis of normal incidence solar UVB radiation and its application to the photoclimatherapy protocol for psoriasis at the Dead Sea, Israel.

    PubMed

    Kudish, Avraham I; Harari, Marco; Evseev, Efim G

    2011-01-01

    The broad-band normal incidence UVB beam radiation has been measured at Neve Zohar, Dead Sea basin, using a prototype tracking instrument composed of a Model 501A UV-Biometer mounted on an Eppley Solar Tracker Model St-1. The diffuse and beam fraction of the solar global UVB radiation have been determined using the concurrently measured solar global UVB radiation. The diffuse fraction was observed to exceed 80% throughout the year. The application of the results of these measurements to the possible revision of the photoclimatherapy protocol for psoriasis patients at the Dead Sea medical spas is now under investigation. The suggested revision would enable the sun-exposure treatment protocol to take advantage of the very high diffuse fraction by allowing the patient to receive the daily dose of UVB radiation without direct exposure to the sun, viz. receive the diffuse UVB radiation under a sunshade. This would require an increase in sun-exposure time intervals, as the UVB radiation intensity beneath a sunshade is less than that on an exposed surface. PMID:21091490

  12. Enhancement of radiation tolerance with the use of a doping superlattice solar cell

    NASA Astrophysics Data System (ADS)

    Slocum, Michael A.; Forbes, David V.; Hubbard, Seth M.

    2014-03-01

    Solar cells utilizing doping superlattices in the active region of the device have been proposed as an alternative design to increase radiation hardness. Multiple diodes are connected together in parallel, where each diode can be as thin or thick as the design requires. Thinning the doped layers reduces the diffusion length requirements ensuring efficient carrier collection and maintenance of short circuit current. Experimental comparisons between nipi and a conventional pin solar cells that were irradiated with 1 MeV electrons at fluences from 4x1014 to 2x1015 e-/cm2 show much more efficient maintenance of efficiency for the nipi design, maintaining nearly 100% efficiency up to a final dose of 2x1015 e-/cm2. Further simulations have indicated that the efficient maintenance of voltage and fill factor are likely due to traps created in the nipi solar cell during the fabrication process. Beginning of life voltage and efficiency values can be improved significantly by limiting the trap density, while this has a minor impact on the efficiency comparison between a nipi and conventional device with respect to radiation.

  13. Silicon space solar cells: progression and radiation-resistance analysis

    NASA Astrophysics Data System (ADS)

    Rehman, Atteq ur; Lee, Sang Hee; Lee, Soo Hong

    2016-02-01

    In this paper, an overview of the solar cell technology based on silicon for applications in space is presented. First, the space environment and its effects on the basis of satellite orbits, such as geostationary earth orbit (GEO) and low earth orbit (LEO), are described. The space solar cell technology based on silicon-based materials, including thin-film silicon solar cells, for use in space was appraised. The evolution of the design for silicon solar cell for use in space, such as a backsurface field (BSF), selective doping, and both-side passivation, etc., is illustrated. This paper also describes the nature of radiation-induced defects and the models proposed for understanding the output power degradation in silicon space solar cells. The phenomenon of an anomalous increase in the short-circuit current ( I sc) in the fluence irradiation range from 2 × 1016 cm-2 to 5 × 1016 cm-2 is also described explicitly from the view point of the various presented models.

  14. Measuring solar UV radiation with EBT radiochromic film.

    PubMed

    Butson, Ethan T; Cheung, Tsang; Yu, Peter K N; Butson, Martin J

    2010-10-21

    Ultraviolet radiation dosimetry has been performed with the use of a radiochromic film dosimeter called Gafchromic EBT for solar radiation exposure. The film changes from a clear colour to blue colour when exposed to ultraviolet radiation and results have shown that the colour change is reproducible within ±10% at 5 kJ m(-2) UV exposure under various conditions of solar radiation. Parameters tested included changes in season (summer versus winter exposure), time of day, as well as sky conditions such as cloudy skies versus clear skies. As the radiochromic films' permanent colour change occurs in the visible wavelengths the film can be analysed with a desktop scanner with the most sensitive channel for analysis being the red component of the signal. Results showed that an exposure of 5 kJ m(-2) (approximately 1 h exposure in full sun during summer) produced an approximate 0.28 change in the net OD when analysed in reflection mode on the desktop scanner which is significant darkening. The main advantages of this film type, and thus the new EBT2 film which has replaced EBT for measurement of UV exposure, is the visible colour change and thus easy analysis using a desktop scanner, its uniformity in response and its robust physical strength for use in outside exposure situations. PMID:20858922

  15. Effect of solar radiation on severity of soybean rust.

    PubMed

    Young, Heather M; George, Sheeja; Narváez, Dario F; Srivastava, Pratibha; Schuerger, Andrew C; Wright, David L; Marois, James J

    2012-08-01

    Soybean rust (SBR), caused by Phakopsora pachyrhizi, is a damaging fungal disease of soybean (Glycine max). Although solar radiation can reduce SBR urediniospore survival, limited information is available on how solar radiation affects SBR progress within soybean canopies. Such information can aid in developing accurate SBR prediction models. To manipulate light penetration into soybean canopies, structures of shade cloth attenuating 30, 40, and 60% sunlight were constructed over soybean plots. In each plot, weekly evaluations of severity in lower, middle, and upper canopies, and daily temperature and relative humidity were recorded. Final plant height and leaf area index were also recorded for each plot. The correlation between amount of epicuticular wax and susceptibility of leaves in the lower, middle, and upper canopies was assessed with a detached leaf assay. Final disease severity was 46 to 150% greater in the lower canopy of all plots and in the middle canopy of 40 and 60% shaded plots. While daytime temperature within the canopy of nonshaded soybean was greater than shaded soybean by 2 to 3°C, temperatures recorded throughout typical evenings and mornings of the growing season in all treatments were within the range (10 to 28.5°C) for SBR development as was relative humidity. This indicates temperature and relative humidity were not limiting factors in this experiment. Epicuticular wax and disease severity in detached leaf assays from the upper canopy had significant negative correlation (P = 0.009, R = -0.84) regardless of shade treatment. In laboratory experiments, increasing simulated total solar radiation (UVA, UVB, and PAR) from 0.15 to 11.66 MJ m(-2) increased mortality of urediniospores from 2 to 91%. Variability in disease development across canopy heights in early planted soybean may be attributed to the effects of solar radiation not only on urediniospore viability, but also on plant height, leaf area index, and epicuticular wax, which influence

  16. Factors affecting the diffusion of solar water disinfection: a field study in Bolivia.

    PubMed

    Heri, Simone; Mosler, Hans-Joachim

    2008-08-01

    This study examines a broad array of theory-based factors derived from diffusion research that affect the current and intended use of solar water disinfection (SODIS), a simple, low-cost technology for treating drinking water at the household level. The perceived attributes of an innovation, the nature of the social system in which it is diffused, the extent of change agents' promotional efforts in diffusing it, and the nature of the communication channels used were operationalized by 16 variables. The aim of the study is to determine the influence of each factor and its predictive power. Eight areas in Bolivia were visited, and 644 families were interviewed on the basis of a structured questionnaire. Simultaneous multiple regression analysis showed that 9 of the 16 factors derived from diffusion research contributed significantly to predicting the current use of SODIS. The implications of the findings for customizing future SODIS diffusion activities are outlined.

  17. The effects of solar radiation on plant growth

    SciTech Connect

    Agard, J.

    1995-09-01

    This phase of this continuing project was completed in April, 1994, using Dahlgren No. 855 hybrid sunflower seeds and Park Seeds No. 0950 non-hybrid sunflower seeds in both the control groups and the tests groups. The control groups (1, 2, 3, 4, 5, and 6) were grown under normal, un-radiated, conditions. The tests groups (1a, 2a, 3a, 4a, 5a, and 6a) were grown onboard the Space Shuttle Discovery on the STS-60 flight in February 1994. All data from this experiment (both control and test groups) will be taken and recorded in a data log and compared against each other to determine the radiation effects of solar radiation on plant germination and growth.

  18. The effects of solar radiation on plant growth

    NASA Technical Reports Server (NTRS)

    Agard, Joslyn

    1995-01-01

    This phase of this continuing project was completed in April, 1994, using Dahlgren #855 hybrid sunflower seeds and Park Seeds #0950 non-hybrid sunflower seeds in both the control groups and the tests groups. The control groups (1, 2, 3, 4, 5, and 6) were grown under normal, un-radiated, conditions. The tests groups (1a, 2a, 3a, 4a, 5a, and 6a) were grown onboard the Space Shuttle Discovery on the STS-60 flight in February 1994. All data from this experiment (both control and test groups) will be taken and recorded in a data log and compared against each other to determine the radiation effects of solar radiation on plant germination and growth.

  19. Analysis of solar radiation on the surface estimated from GWNU solar radiation model with temporal resolution of satellite cloud fraction

    NASA Astrophysics Data System (ADS)

    Zo, Il-Sung; Jee, Joon-Bum; Lee, Kyu-Tae; Kim, Bu-Yo

    2016-08-01

    Preliminary analysis with a solar radiation model is generally performed for photovoltaic power generation projects. Therefore, model accuracy is extremely important. The temporal and spatial resolutions used in previous studies of the Korean Peninsula were 1 km × 1 km and 1-h, respectively. However, calculating surface solar radiation at 1-h intervals does not ensure the accuracy of the geographical effects, and this parameter changes owing to atmospheric elements (clouds, aerosol, ozone, etc.). Thus, a change in temporal resolution is required. In this study, one-year (2013) analysis was conducted using Chollian geostationary meteorological satellite data from observations recorded at 15-min intervals. Observation data from the intensive solar site at Gangneung-Wonju National University (GWNU) showed that the coefficient of determination (R²), which was estimated for each month and season, increased, whereas the standard error (SE) decreased when estimated in 15-min intervals over those obtained in 1-h intervals in 2013. When compared with observational data from 22 solar sites of the Korean Meteorological Administration (KMA), R2 was 0.9 or higher on average, and over- or under-simulated sites did not exceed 3 sites. The model and 22 solar sites showed similar values of annual accumulated solar irradiation, and their annual mean was similar at 4,998 MJ m-2 (3.87 kWh m-2). These results show a difference of approximately ± 70 MJ m-2 (± 0.05 kWh m-2) from the distribution of the Korean Peninsula estimated in 1-h intervals and a higher correlation at higher temporal resolution.

  20. Effects of solar UV-B radiation on aquatic ecosystems

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.

    Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO 2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position

  1. Effects of solar UV-B radiation on aquatic ecosystems.

    PubMed

    Hader, D P

    2000-01-01

    Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position

  2. Aerosols attenuating the solar radiation collected by solar tower plants: The horizontal pathway at surface level

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Ramon, Didier; Dubus, Laurent; Bourdil, Charles; Cuevas-Agulló, Emilio; Zaidouni, Taoufik; Formenti, Paola

    2016-05-01

    Aerosols attenuate the solar radiation collected by solar tower plants (STP), along two pathways: 1) the atmospheric column pathway, between the top of the atmosphere and the heliostats, resulting in Direct Normal Irradiance (DNI) changes; 2) the grazing pathway close to surface level, between the heliostats and the optical receiver. The attenuation along the surface-level grazing pathway has been less studied than the aerosol impact on changes of DNI, while it becomes significant in STP of 100 MW or more. Indeed aerosols mostly lay within the surface atmospheric layer, called the boundary layer, and the attenuation increases with the distance covered by the solar radiation in the boundary layer. In STP of 100 MW or more, the distance between the heliostats and the optical receiver becomes large enough to produce a significant attenuation by aerosols. We used measured aerosol optical thickness and computed boundary layer height to estimate the attenuation of the solar radiation at surface level at Ouarzazate (Morocco). High variabilities in aerosol amount and in vertical layering generated a significant magnitude in the annual cycle and significant inter-annual changes. Indeed the annual mean of the attenuation caused by aerosols over a 1-km heliostat-receiver distance was 3.7% in 2013, and 5.4% in 2014 because of a longest desert dust season. The monthly minimum attenuation of less than 3% was observed in winter and the maximum of more than 7% was observed in summer.

  3. Solar UV Radiation and the Origin of Life on Earth

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Hubeny, Ivan; Lanz, Thierry; Gaidos, Eric; Kasting, James; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    We have started a comprehensive, interdisciplinary study of the influence of solar ultraviolet radiation on the atmosphere of of the early Earth. We plan to model the chemistry of the Earth atmosphere during its evolution, using observed UV flux distributions of early solar analogs as boundary conditions in photochemical models of the Earth's atmosphere. The study has four distinct but interlinked parts: (1) Establishing the radiation of the early Sun; (2) Determining the photochemistry of the early Earth's atmosphere; (3) Estimating the rates of H2 loss from the atmosphere; and (4) Ascertaining how sensitive is the photochemistry to the metallicity of the Sun. We are currently using STIS and EUVE to obtain high-quality far-UV and extreme-UV observations of three early-solar analogs. We will perform a detailed non-LTE study of each stars, and construct theoretical model photosphere, and an empirical model chromospheres, which can be used to extrapolate the continuum to the Lyman continuum region. Given a realistic flux distribution of the early Sun, we will perform photochemical modeling of weakly reducing primitive atmospheres to determine the lifetime and photochemistry of CH4. In particular, we will make estimates of the amount of CH4 present in the prebiotic atmosphere, and estimate the atmospheric CH4 concentration during the Late Archean (2.5-3.0 b.y. ago) and determine whether it would have been sufficiently abundant to help offset reduced solar luminosity at that time. Having obtained a photochemical model, we will solve for the concentrations of greenhouse gasses and important pre-biotic molecules, and perform a detailed radiative transfer calculations to compute the UV flux reaching the surface.

  4. Solar Radiation Pressure Binning for the Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Hejduk, M. D.; Ghrist, R. W.

    2011-01-01

    Orbital maintenance parameters for individual satellites or groups of satellites have traditionally been set by examining orbital parameters alone, such as through apogee and perigee height binning; this approach ignored the other factors that governed an individual satellite's susceptibility to non-conservative forces. In the atmospheric drag regime, this problem has been addressed by the introduction of the "energy dissipation rate," a quantity that represents the amount of energy being removed from the orbit; such an approach is able to consider both atmospheric density and satellite frontal area characteristics and thus serve as a mechanism for binning satellites of similar behavior. The geo-synchronous orbit (of broader definition than the geostationary orbit -- here taken to be from 1300 to 1800 minutes in orbital period) is not affected by drag; rather, its principal non-conservative force is that of solar radiation pressure -- the momentum imparted to the satellite by solar radiometric energy. While this perturbation is solved for as part of the orbit determination update, no binning or division scheme, analogous to the drag regime, has been developed for the geo-synchronous orbit. The present analysis has begun such an effort by examining the behavior of geosynchronous rocket bodies and non-stabilized payloads as a function of solar radiation pressure susceptibility. A preliminary examination of binning techniques used in the drag regime gives initial guidance regarding the criteria for useful bin divisions. Applying these criteria to the object type, solar radiation pressure, and resultant state vector accuracy for the analyzed dataset, a single division of "large" satellites into two bins for the purposes of setting related sensor tasking and orbit determination (OD) controls is suggested. When an accompanying analysis of high area-to-mass objects is complete, a full set of binning recommendations for the geosynchronous orbit will be available.

  5. Effects of Refractive Index and Diffuse or Specular Boundaries on a Radiating Isothermal Layer

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1994-01-01

    Equilibrium temperatures of an absorbing-emitting layer were obtained for exposure to incident radiation and with the layer boundaries either specular or diffuse. For high refractive indices the surface condition can influence the radiative heat balance if the layer optical thickness is small. Hence for a spectrally varying absorption coefficient the layer temperature is affected if there is significant radiative energy in the spectral range with a small absorption coefficient. Similar behavior was obtained for transient radiative cooling of a layer where the results are affected by the initial temperature and hence the fraction of energy radiated in the short wavelength region where the absorption coefficient is small. The results are a layer without internal scattering. If internal scattering is significant, the radiation reaching the internal surface of a boundary is diffused and the effect of the two different surface conditions would become small.

  6. Radiative diffusivity factors in cirrus and stratocumulus clouds: Application to two-stream models

    NASA Technical Reports Server (NTRS)

    Stephens, Graeme L.; Flatau, P. J.; Tsay, S.-C.; Hein, Paul F.

    1990-01-01

    A diffusion-like description of radiative transfer in clouds and the free atmosphere is often used. The two stream model is probably the best known example of such a description. The main idea behind the approach is that only the first few moments of radiance are needed to describe the radiative field correctly. Integration smooths details of the angular distribution of specific intensity and it is assumed that the closure parameters of the theory (diffusivity factors) are only weakly dependent on the distribution. The diffusivity factors are investigated using the results obtained from both Stratocumulus and Cirrus phases of FIRE experiment. A new theoretical framework is described in which two (upwards and downwards) diffusivity factors are used and a detailed multistream model is used to provide further insight about both the diffusivity factors and their dependence on scattering properties of clouds.

  7. Advances in Radiation-Tolerant Solar Arrays for SEP Missions

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Eskenazi, Michael I.; Ferguson, Dale C.

    2007-01-01

    As the power levels of commercial communications satellites reach the 20 kWe and higher, new options begin to emerge for transferring the satellite from LEO to GEO. In the past electric propulsion has been demonstrated successfully for this mission - albeit under unfortunate circumstances when the kick motor failed. The unexpected use of propellant for the electric propulsion (EP) system compromised the life of that vehicle, but did demonstrate the viability of such an approach. Replacing the kick motor on a satellite and replacing that mass by additional propellant for the EP system as well as mass for additional revenue-producing transponders should lead to major benefits for the provider. Of course this approach requires that the loss in solar array power during transit of the Van Allen radiation belts is not excessive and still enables the 15 to 20 year mission life. In addition, SEP missions to Jupiter, with its exceptional radiation belts, would mandate a radiation-resistant solar array to compete with a radioisotope alternative. Several critical issues emerge as potential barriers to this approach: reducing solar array radiation damage, operating the array at high voltage (>300 V) for extended times for Hall or ion thrusters, designing an array that will be resistant to micrometeoroid impacts and the differing environmental conditions as the vehicle travels from LEO to GEO (or at Jupiter), producing an array that is light weight to preserve payload mass fraction - and to do this at a cost that is lower than today's arrays. This paper will describe progress made to date on achieving an array that meets all these requirements and is also useful for deep space electric propulsion missions.

  8. Degradation of bulk diffusion length in CZ silicon solar cells

    SciTech Connect

    Reiss, J.H.; King, R.R.; Mitchell, K.W.

    1995-08-01

    Commercially-produced, unencapsulated, CZ silicon solar cells can lose 3 to 4% of their initial efficiency after exposure to light. After this initial, rapid ( < 30 min.) decrease, the cell power output remains stable. The cell performance recovers in a matter of hours in the dark at room temperature, and degrades again under light exposure. The different conditions under which CZ silicon cells degrade, and the reverse process, annealing, are characterized with the methods of spectral response and current-voltage (I-V) measurements. Iron impurities are a possible cause of this effect.

  9. BOREAS HYD-3 Subcanopy Incoming Solar Radiation Measurements

    NASA Technical Reports Server (NTRS)

    Hardy, Janet P.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Davis, Robert E.; Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-3 team collected several data sets related to the hydrology of forested areas. This data set contains solar radiation measurements from several pyranometers (solar radiometers) placed on the snow surface in jack pine (1994) and black spruce and aspen forests (1996) in the BOREAS southern study area (SSA). An array of radiometers was used to collect data for three to four consecutive days in each forest type to study the hypothesis that energy transfer and snow water equivalent would vary spatially as a function of canopy closure. The quality of the data is good, because the days were generally clear and the radiometers were checked daily to remove anything that landed on the radiometers. The data are available in tabular ASCII files. The subcanopy incoming solar radiation measurement data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  10. Electron Radiation Damage of (alga) As-gaas Solar Cells

    NASA Technical Reports Server (NTRS)

    Loo, R.; Kamath, G. S.; Knechtli, R.

    1979-01-01

    Solar cells (2 cm by 2 cm (AlGa) As-GaAs cells) were fabricated and then subjected to irradiation at normal incidence by electrons. The influence of junction depth and n-type buffer layer doping level on the cell's resistance to radiation damage was investigated. The study shows that (1) a 0.3 micrometer deep junction results in lower damage to the cells than does a 0.5 micrometer junction, and (2) lowering the n buffer layer doping density does not improve the radiation resistance of the cell. Rather, lowering the doping density decreases the solar cell's open circuit voltage. Some preliminary thermal annealing experiments in vacuum were performed on the (AlGa)As-GaAs solar cells damaged by 1-MeV electron irradiation. The results show that cell performance can be expected to partially recover at 200 C with more rapid and complete recovery occurring at higher temperature. For a 0.5hr anneal at 400 C, 90% of the initial power is recovered. The characteristics of the (AlGa)As-GaAs cells both before and after irradiation are described.

  11. Impact of buildings on surface solar radiation over urban Beijing

    NASA Astrophysics Data System (ADS)

    Zhao, Bin; Liou, Kuo-Nan; Gu, Yu; He, Cenlin; Lee, Wee-Liang; Chang, Xing; Li, Qinbin; Wang, Shuxiao; Tseng, Hsien-Liang R.; Leung, Lai-Yung R.; Hao, Jiming

    2016-05-01

    The rugged surface of an urban area due to varying buildings can interact with solar beams and affect both the magnitude and spatiotemporal distribution of surface solar fluxes. Here we systematically examine the impact of buildings on downward surface solar fluxes over urban Beijing by using a 3-D radiation parameterization that accounts for 3-D building structures vs. the conventional plane-parallel scheme. We find that the resulting downward surface solar flux deviations between the 3-D and the plane-parallel schemes are generally ±1-10 W m-2 at 800 m grid resolution and within ±1 W m-2 at 4 km resolution. Pairs of positive-negative flux deviations on different sides of buildings are resolved at 800 m resolution, while they offset each other at 4 km resolution. Flux deviations from the unobstructed horizontal surface at 4 km resolution are positive around noon but negative in the early morning and late afternoon. The corresponding deviations at 800 m resolution, in contrast, show diurnal variations that are strongly dependent on the location of the grids relative to the buildings. Both the magnitude and spatiotemporal variations of flux deviations are largely dominated by the direct flux. Furthermore, we find that flux deviations can potentially be an order of magnitude larger by using a finer grid resolution. Atmospheric aerosols can reduce the magnitude of downward surface solar flux deviations by 10-65 %, while the surface albedo generally has a rather moderate impact on flux deviations. The results imply that the effect of buildings on downward surface solar fluxes may not be critically significant in mesoscale atmospheric models with a grid resolution of 4 km or coarser. However, the effect can play a crucial role in meso-urban atmospheric models as well as microscale urban dispersion models with resolutions of 1 m to 1 km.

  12. MAGNETIC TRANSPORT ON THE SOLAR ATMOSPHERE BY LAMINAR AND TURBULENT AMBIPOLAR DIFFUSION

    SciTech Connect

    Hiraki, Y.; Krishan, V.; Masuda, S.

    2010-09-10

    The lower solar atmosphere consists of partially ionized turbulent plasmas harboring velocity field, magnetic field, and current density fluctuations. The correlations among these small-scale fluctuations give rise to large-scale flows and magnetic fields which decisively affect all transport processes. The three-fluid system consisting of electrons, ions, and neutral particles supports nonideal effects such as the Hall effect and ambipolar diffusion. Here, we study magnetic transport by the laminar- and turbulent-scale ambipolar diffusion processes using a simple model of the magnetic induction equation. Based on a linear analysis of the induction equation, we perform a one-dimensional numerical simulation to study the laminar ambipolar effect on medium-scale magnetic field structures. The nonlinearity of the laminar ambipolar diffusion creates magnetic structures with sharp gradients in the scale of hundreds of kilometers. We expect that these can be amenable to processes such as magnetic reconnection and energy release therefrom for heating and flaring of the solar plasma. Analyzing the characteristic timescales of these processes, we find that the turbulent diffusion timescale is smaller by several orders of magnitude than the laminar diffusion timescale. The effect of the modeled turbulent ambipolar diffusion on the obtained field structures is briefly discussed.

  13. Can we predict solar radiation at seasonal time-scale over Europe? A renewable energy perspective.

    NASA Astrophysics Data System (ADS)

    De Felice, Matteo; Alessandri, Andrea

    2015-04-01

    Surface solar radiation can be an important variable for the activities related to renewable energies (photovoltaic) and agriculture. Having accurate forecast may be of potential use for planning and operational tasks. This study examines the predictability of seasonal surface solar radiation comparing ECMWF System4 Seasonal operational forecasts with reanalyses (ERA-INTERIM, MERRA) and other datasets (NASA/GEWEX SRB, WFDEI). This work is focused on the period 1984-2007 and it tries to answer the following questions: 1) How similar are the chosen datasets looking at average and interannual variability? 2) What is the skill of seasonal forecasts in predicting solar radiation? 3) Is it useful for solar power operations and planning the seasonal prediction of solar radiation? It is important to assess the capability of climate datasets in describing surface solar radiation but at the same time it is critical to understand the needs of solar power industry in order to find the right problems to tackle.

  14. Numerical model of solar dynamic radiator for parametric analysis

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.

    1989-01-01

    Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. The SD module rejects waste heat from the power conversion cycle to space through a pumped-loop, multi-panel, deployable radiator. The baseline radiator configuration was defined during the Space Station conceptual design phase and is a function of the state point and heat rejection requirements of the power conversion unit. Requirements determined by the overall station design such as mass, system redundancy, micrometeoroid and space debris impact survivability, launch packaging, costs, and thermal and structural interaction with other station components have also been design drivers for the radiator configuration. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations. A brief description and discussion of the numerical model, it's capabilities and limitations, and results of the parametric studies performed is presented.

  15. Solar modulation of the cosmic radiation in the heliosphere

    NASA Technical Reports Server (NTRS)

    Mckibben, R. B.

    1987-01-01

    Changes in the solar modulation of galactic and anomalous component cosmic rays reflect changes in the structure and magnetic topology of the interplanetary medium. Therefore, to the extent that the modulation process is understood, the cosmic rays can be used as a probe of the medium to infer the extent and structure of the heliosphere in regions not directly sampled by spacecraft. The challenge to modulation theory and observation has been to determine which properties of the solar wind are most important for producing the observed modulation. Significant progress has been made in answering this question during the last solar cycle using observations from spacecraft at radii to 40 AU from the Sun and at latitudes up to 30 degrees with respect to the ecliptic. A brief summary of new results and observations (with specific attention to the STIP intervals XV-XIX) will be presented to illustrate the present state of our understanding of the relation between the solar wind and interplanetary magnetic field and the modulations of the cosmic radiation.

  16. Impacts of wind stilling on solar radiation variability in China.

    PubMed

    Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

    2015-01-01

    Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling. PMID:26463748

  17. Impacts of wind stilling on solar radiation variability in China.

    PubMed

    Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

    2015-01-01

    Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling.

  18. Impacts of wind stilling on solar radiation variability in China

    NASA Astrophysics Data System (ADS)

    Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

    2015-10-01

    Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling.

  19. A Proposal for a Thesaurus for Web Services in Solar Radiation

    NASA Technical Reports Server (NTRS)

    Gschwind, Benoit; Menard, Lionel; Ranchin, Thierry; Wald, Lucien; Stackhouse, Paul W., Jr.

    2007-01-01

    Metadata are necessary to discover, describe and exchange any type of information, resource and service at a large scale. A significant amount of effort has been made in the field of geography and environment to establish standards. Efforts still remain to address more specific domains such as renewable energies. This communication focuses on solar energy and more specifically on aspects in solar radiation that relate to geography and meteorology. A thesaurus in solar radiation is proposed for the keys elements in solar radiation namely time, space and radiation types. The importance of time-series in solar radiation is outlined and attributes of the key elements are discussed. An XML schema for encoding metadata is proposed. The exploitation of such a schema in web services is discussed. This proposal is a first attempt at establishing a thesaurus for describing data and applications in solar radiation.

  20. Modulation of the Southern Hemisphere climate by solar radiation management

    NASA Astrophysics Data System (ADS)

    Phipps, Steven; Lenton, Andrew; Rotstayn, Leon; Gupta, Alex Sen; Ji, Duoying; Moore, John; Niemeier, Ulrike; Schmidt, Hauke; Tilmes, Simone

    2015-04-01

    Geoengineering is increasingly being considered as a means to lessen the climatic impacts of anthropogenic greenhouse gas emissions. However, it is not without significant risks of its own. In this study, we investigate the response of the Southern Hemisphere (SH) climate to solar radiation management (SRM) using Geoengineering Model Intercomparison Project experiments G3 and G3solar. We find that the response to SRM is characterized by a contraction of the Hadley Cell and subtropical dry zones. This is accompanied by a shift towards a less positive state of the Southern Annular Mode and a northward shift of the SH westerly winds, mitigating the trends under projected future anthropogenic forcing. These changes result in an increase in precipitation minus evaporation in the SH subtropics, suggesting that SRM may be effective at counteracting the anthropogenically-driven drying trend in this region. However, any beneficial impacts cease abruptly as soon as geoengineering is terminated.

  1. Do satellites detect trends in surface solar radiation?

    PubMed

    Pinker, R T; Zhang, B; Dutton, E G

    2005-05-01

    Long-term variations in solar radiation at Earth's surface (S) can affect our climate, the hydrological cycle, plant photosynthesis, and solar power. Sustained decreases in S have been widely reported from about the year 1960 to 1990. Here we present an estimate of global temporal variations in S by using the longest available satellite record. We observed an overall increase in S from 1983 to 2001 at a rate of 0.16 watts per square meter (0.10%) per year; this change is a combination of a decrease until about 1990, followed by a sustained increase. The global-scale findings are consistent with recent independent satellite observations but differ in sign and magnitude from previously reported ground observations. Unlike ground stations, satellites can uniformly sample the entire globe. PMID:15879215

  2. Radiative transfer of X-rays in the solar corona

    NASA Technical Reports Server (NTRS)

    Acton, L. W.

    1978-01-01

    The problem of resonance scattering of X-ray emission lines in the solar corona is investigated. For the resonance lines of some helium-like ions, significant optical depths are reached over distances small compared with the size of typical coronal features. A general integral equation for the transfer of resonance-line radiation under solar coronal conditions is derived. This expression is in a form useful for modeling the complex three-dimensional temperature and density structure of coronal active regions. The transfer equation is then cast in a form illustrating the terms which give rise to the attenuation or enhancement of the resonance-line intensity. The source function for helium-like oxygen (O VII) under coronal conditions is computed and discussed in terms of the relative importance of scattering.

  3. A fast all-sky radiative transfer model and its implications for solar energy research

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Sengupta, M.

    2015-12-01

    Radiative transfer models simulating broadband solar radiation, e.g. Rapid Radiation Transfer Model (RRTM) and its GCM applications, have been widely used by atmospheric scientists to model solar resource for various energy applications such as operational forecasting. Due to the complexity of solving the radiative transfer equation, simulating solar radiation under cloudy conditions can be extremely time consuming though many approximations, e.g. two-stream approach and delta-M truncation scheme, have been utilized. To provide a new option to approximate solar radiation, we developed a Fast All-sky Radiation Model for Solar applications (FARMS) using simulated cloud transmittance and reflectance from 16-stream RRTM model runs. The solar irradiances at the land surface were simulated by combining parameterized cloud properties with a fast clear-sky radiative transfer model. Using solar radiation measurements from the US Department of Energy's Atmospheric Radiation Measurement (ARM) central facility in Oklahoma as a benchmark against the model simulations, we were able to demonstrate that the accuracy of FARMS was comparable to the two-stream approach. However, FARMS is much more efficient since it does not explicitly solve the radiative transfer equation for each individual cloud condition. We further explored the use of FARMS to promote solar resource assessment and forecasting research through the increased ability to accommodate higher spatial and temporal resolution calculations for the next generation of satellite and numerical weather prediction (NWP) models.

  4. Trends of the sunshine duration and diffuse radiation percentage on sunny days in urban agglomerations of China during 1960-2005.

    PubMed

    Fu, Chuanbo; Dan, Li; Chen, Youlong; Tang, Jiaxiang

    2015-08-01

    The long-term observational data of sunshine duration (SD) and diffuse radiation percentage (defined as diffuse solar radiation/total solar radiation, DRP) on sunny days during 1960-2005 were analyzed in 7 urban agglomerations and the whole of China. The results show that the sunny sunshine duration (SSD) has decreased significantly except at a few stations over northwestern China in the past 46 years. An obvious decrease of the SSD is found in eastern China, with the trend coefficients lower than -0.8. Accompanied by the SSD decline, the sunny diffuse radiation percentage (SDRP) in most stations shows obvious increasing trends during the 46 years. The averaged SDRP over China has increased 2.33% per decade, while the averaged SSD shows a decrease of -0.13 hr/day per decade. The correlation coefficient between SDRP and SSD is -0.88. SSD decreased over urban agglomerations (small to large city clusters) in the past 46 years, especially in large cities and medium cities, due to the strong anthropogenic activities and air pollution represented by aerosol option depth (AOD) and tropospheric column NO2 (TroNO2). On the regional scale, SSD has an opposite trend from SDRP during 1960 to 2005, and the variation trends of regional mean values of SSD and SDRP in southeastern China are more pronounced than those in northwestern China.

  5. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    PubMed Central

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q.-G.; Zhou, X.-Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y.-X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Wygant, J. R.

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons. PMID:26690250

  6. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.

    PubMed

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons. PMID:26690250

  7. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    SciTech Connect

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q. -G.; Zhou, X. -Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y. -X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Wygant, J. R.

    2015-12-22

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.

  8. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    DOE PAGESBeta

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q. -G.; Zhou, X. -Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y. -X.; Gao, Zhonglei; et al

    2015-12-22

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULFmore » waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.« less

  9. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.

    PubMed

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.

  10. Image dissector photocathode solar damage test program. [solar radiation shielding using a fast optical lens

    NASA Technical Reports Server (NTRS)

    Smith, R. A.

    1977-01-01

    Image dissector sensors of the same type which will be used in the NASA shuttle star tracker were used in a series of tests directed towards obtaining solar radiation/time damage criteria. Data were evaluated to determine the predicted level of operability of the star tracker if tube damage became a reality. During the test series a technique for reducing the solar damage effect was conceived and verified. The damage concepts are outlined and the test methods and data obtained which were used for verification of the technique's feasibility are presented. The ability to operate an image dissector sensor with the solar image focussed on the photocathode by a fast optical lens under certain conditions is feasible and the elimination of a mechanical protection device is possible.

  11. Hybrid Perovskites for Photovoltaics: Charge-Carrier Recombination, Diffusion, and Radiative Efficiencies.

    PubMed

    Johnston, Michael B; Herz, Laura M

    2016-01-19

    values extracted from OPTP measurements and their dependence on perovskite composition and morphology. The significance of the reviewed charge-carrier recombination and mobility parameters is subsequently evaluated in terms of the charge-carrier diffusion lengths and radiative efficiencies that may be obtained for such hybrid perovskites. We particularly focus on calculating such quantities in the limit of ultra-low trap-related recombination, which has not yet been demonstrated but could be reached through further advances in material processing. We find that for thin films of hybrid lead iodide perovskites with typical charge-carrier mobilities of ∼30cm(2)/(V s), charge-carrier diffusion lengths at solar (AM1.5) irradiation are unlikely to exceed ∼10 μm even if all trap-related recombination is eliminated. We further examine the radiative efficiency for hybrid lead halide perovskite films and show that if high efficiencies are to be obtained for intermediate charge-carrier densities (n ≈ 10(14) cm(-3)) trap-related recombination lifetimes will have to be enhanced well into the microsecond range. PMID:26653572

  12. THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES OBSERVED WITH AIA/SDO: FRACTAL DIFFUSION, SUB-DIFFUSION, OR LOGISTIC GROWTH?

    SciTech Connect

    Aschwanden, Markus J.

    2012-09-20

    We explore the spatio-temporal evolution of solar flares by fitting a radial expansion model r(t) that consists of an exponentially growing acceleration phase, followed by a deceleration phase that is parameterized by the generalized diffusion function r(t){proportional_to}{kappa}(t - t{sub 1}){sup {beta}/2}, which includes the logistic growth limit ({beta} = 0), sub-diffusion ({beta} = 0-1), classical diffusion ({beta} = 1), super-diffusion ({beta} = 1-2), and the linear expansion limit ({beta} = 2). We analyze all M- and X-class flares observed with Geostationary Operational Environmental Satellite and Atmospheric Imaging Assembly/Solar Dynamics Observatory (SDO) during the first two years of the SDO mission, amounting to 155 events. We find that most flares operate in the sub-diffusive regime ({beta} = 0.53 {+-} 0.27), which we interpret in terms of anisotropic chain reactions of intermittent magnetic reconnection episodes in a low plasma-{beta} corona. We find a mean propagation speed of v = 15 {+-} 12 km s{sup -1}, with maximum speeds of v{sub max} = 80 {+-} 85 km s{sup -1} per flare, which is substantially slower than the sonic speeds expected for thermal diffusion of flare plasmas. The diffusive characteristics established here (for the first time for solar flares) is consistent with the fractal-diffusive self-organized criticality model, which predicted diffusive transport merely based on cellular automaton simulations.

  13. Low temperature Zn diffusion for GaSb solar cell structures fabrication

    NASA Technical Reports Server (NTRS)

    Sulima, Oleg V.; Faleev, Nikolai N.; Kazantsev, Andrej B.; Mintairov, Alexander M.; Namazov, Ali

    1995-01-01

    Low temperature Zn diffusion in GaSb, where the minimum temperature was 450 C, was studied. The pseudo-closed box (PCB) method was used for Zn diffusion into GaAs, AlGaAs, InP, InGaAs and InGaAsP. The PCB method avoids the inconvenience of sealed ampoules and proved to be simple and reproducible. The special design of the boat for Zn diffusion ensured the uniformality of Zn vapor pressure across the wafer surface, and thus the uniformity of the p-GaSb layer depth. The p-GaSb layers were studied using Raman scattering spectroscopy and the x-ray rocking curve method. As for the postdiffusion processing, an anodic oxidation was used for a precise thinning of the diffused GaSb layers. The results show the applicability of the PCB method for the large-scale production of the GaSb structures for solar cells.

  14. Particle energization during solar maximum: Diffusive shock acceleration at multiple shocks

    SciTech Connect

    Neergaard Parker, L.; Zank, G. P.

    2014-08-01

    We present a model for the acceleration of particles at multiple shocks using an approach related to box models. A distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles out of the box by either the method used in Melrose and Pope and Pope and Melrose or by the approach introduced in Zank et al. where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (E{sub max}) appropriate for quasi-parallel and quasi-perpendicular shocks. We provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum.

  15. Particle Energization during Solar Maximum: Diffusive Shock Acceleration at Multiple Shocks

    NASA Astrophysics Data System (ADS)

    Neergaard Parker, L.; Zank, G. P.

    2014-08-01

    We present a model for the acceleration of particles at multiple shocks using an approach related to box models. A distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles out of the box by either the method used in Melrose & Pope and Pope & Melrose or by the approach introduced in Zank et al. where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (E max) appropriate for quasi-parallel and quasi-perpendicular shocks. We provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum.

  16. Radiation effects in silicon and gallium arsenide solar cells using isotropic and normally incident radiation

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Downing, R. G.

    1984-01-01

    Several types of silicon and gallium arsenide solar cells were irradiated with protons with energies between 50 keV and 10 MeV at both normal and isotropic incidence. Damage coefficients for maximum power relative to 10 MeV were derived for these cells for both cases of omni-directional and normal incidence. The damage coefficients for the silicon cells were found to be somewhat lower than those quoted in the Solar Cell Radiation Handbook. These values were used to compute omni-directional damage coefficients suitable for solar cells protected by coverglasses of practical thickness, which in turn were used to compute solar cell degradation in two proton-dominated orbits. In spite of the difference in the low energy proton damage coefficients, the difference between the handbook prediction and the prediction using the newly derived values was negligible. Damage coefficients for GaAs solar cells for short circuit current, open circuit voltage, and maximum power were also computed relative to 10 MeV protons. They were used to predict cell degradation in the same two orbits and in a 5600 nmi orbit. Results show the performance of the GaAs solar cells in these orbits to be superior to that of the Si cells.

  17. Step-by-Step Simulation of Radiation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    The irradiation of biological systems leads to the formation of radiolytic species such as H(raised dot), (raised dot)OH, H2, H2O2, e(sup -)(sub aq), etc.[1]. These species react with neighboring molecules, which result in damage in biological molecules such as DNA. Radiation chemistry is there for every important to understand the radiobiological consequences of radiation[2]. In this work, we discuss an approach based on the exact Green Functions for diffusion-influenced reactions which may be used to simulate radiation chemistry and eventually extended to study more complex systems, including DNA.

  18. Disentangling leaf area and environmental effects on the response of the net ecosystem CO2 exchange to diffuse radiation.

    PubMed

    Wohlfahrt, Georg; Hammerle, Albin; Haslwanter, Alois; Bahn, Michael; Tappeiner, Ulrike; Cernusca, Alexander

    2008-08-01

    There is an ongoing discussion about why the net ecosystem CO2 exchange (NEE) of some ecosystems is less sensitive to diffuse radiation than others and about the role other environmental factors play in determining the response of NEE to diffuse radiation. Using a six-year data set from a temperate mountain grassland in Austria we show that differences between ecosystems may be reconciled based on their green area index (GAI; square meter green plant area per square meter ground area) - the sensitivity to diffuse radiation increasing with GAI. Our data suggest diffuse radiation to have a negligible influence on NEE below a GAI of 2 m(2) m(-2). Changes in air/soil temperature and air humidity concurrent with the fraction of diffuse radiation were found to amplify the sensitivity of the investigated temperate mountain grassland ecosystem to diffuse radiation.

  19. Solar Cycle Variation and Application to the Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Kim, Myung-Hee Y.; Shinn, Judy L.; Tai, Hsiang; Cucinotta, Francis A.; Badhwar, Gautam D.; Badavi, Francis F.; Atwell, William

    1999-01-01

    The interplanetary plasma and fields are affected by the degree of disturbance that is related to the number and types of sunspots in the solar surface. Sunspot observations were improved with the introduction of the telescope in the seventeenth century, allowing observations which cover many centuries. A single quantity (sunspot number) was defined by Wolf in 1848 that is now known to be well correlated with many space observable quantities and is used herein to represent variations caused in the space radiation environment. The resultant environmental models are intended for future aircraft and space-travel-related exposure estimates.

  20. A possible radiation-resistant solar cell geometry using superlattices

    NASA Technical Reports Server (NTRS)

    Goradia, C.; Clark, R.; Brinker, D.

    1985-01-01

    A solar cell structure is proposed which uses a GaAs nipi doping superlattice. An important feature of this structure is that photogenerated minority carriers are very quickly collected in a time shorter than bulk lifetime in the fairly heavily doped n and p layers and these carriers are then transported parallel to the superlattice layers to selective ohmic contacts. Assuming that these already-separated carriers have very long recombination lifetimes, due to their across an indirect bandgap in real space, it is argued that the proposed structure may exhibit superior radiation tolerance along with reasonably high beginning-of-life efficiency.

  1. Variability of surface solar radiation in unforced CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Folini, Doris; Wild, Martin

    2016-04-01

    We examine the natural variability of surface solar radiation (SSR) under pre-industrial conditions with time-invariant forcing in control runs in global climate simulations of the latest coupled model intercomparison project, CMIP5. We consider global and regional scales, as well as annual and seasonal data. Special emphasis is given to the likelihood of spurious SSR trends. To address this question, we determine for each model the range of linear SSR trends as function of the number of years over which the trend is taken. We discuss our findings with regard to potential aerosol induced dimming and its detectability in the second half of the 20th century.

  2. Solar Radiation Monitoring Station (SoRMS): Humboldt State University, Arcata, California (Data)

    DOE Data Explorer

    Wilcox, S.; Andreas, A.

    2007-05-02

    A partnership with HSU and U.S. Department of Energy's National Renewable Energy Laboratory (NREL) to collect solar data to support future solar power generation in the United States. The measurement station monitors global horizontal, direct normal, and diffuse horizontal irradiance to define the amount of solar energy that hits this particular location.

  3. The impact of solar UV radiation on the early biosphere

    NASA Astrophysics Data System (ADS)

    Horneck, G.

    2007-08-01

    Stratospheric ozone, photochemically produced from atmospheric oxygen, is a protective filter of the Earth's atmosphere by absorbing most of the biologically harmful UV radiation of our sun in the UV-C (190-280 nm) and short wavelength-region of the UV-B (280-315 nm). Numerous lines of isotopic and geologic evidence suggest that the Archean atmosphere was essentially anoxic. As a result the column abundance of ozone would have been insufficient to affect the surface UV radiation environment. Thus, as well as UV-B radiation, UV-C radiation would have penetrated to the Earth's surface with its associated biological consequences. The history of this ultraviolet stress for the early Earth has been determined from theoretical data and data obtained in Earth orbit on the inactivation of Bacillus subtilis spores under a simulated ozone layer of different thicknesses. Although the UV-C and UV-B regions contribute only 2 % of the entire solar extraterrestrial irradiance, photobiological experiments in space have demonstrated a high mutagenicity and lethality of this UV range to living organisms. The reason for these severe effects of extraterrestrial solar UV radiation - compared to conditions on present-day Earth - lies in the absorption characteristics of the DNA, which is the decisive target for inactivation and mutation induction at this UV range. Being a strong mutagen, UV-radiation is considered as a powerful promoter of biological evolution on the one hand, one the other hand, it may have deleterious consequences to individual cells and organisms, e.g. by causing inactivation, mutations or cancer induction. In response to potential harmful effects of environmental UV radiation, life on Earth has developed several strategies of survival, either avoiding exposure to UV radiation or restoring UV damage. Mechanisms of avoidance of exposure to UV radiation include (i) moving away from the UV radiation into shadowed areas, which requires the development of UV radiation

  4. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

    PubMed Central

    van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F.; Kilpatrick, Trevor J.

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = −0.428, p = 0.009; MD: R = −0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage. PMID:27555964

  5. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis.

    PubMed

    Kolbe, Scott C; van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F; Kilpatrick, Trevor J

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of -2.6% per annum (control = -0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = -0.428, p = 0.009; MD: R = -0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

  6. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis.

    PubMed

    Kolbe, Scott C; van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F; Kilpatrick, Trevor J

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of -2.6% per annum (control = -0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = -0.428, p = 0.009; MD: R = -0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage. PMID:27555964

  7. Pulsar and diffuse contributions to observed galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1981-01-01

    The first calculation of a gamma-ray production spectrum from pulsars in the Galaxy, along with a statistical analysis of data on 328 known radio pulsars, are presented. The implications of this point source contribution to the general interpretation of the observed galactic gamma-ray spectrum are indicated. The contributions from diffuse interstellar cosmic-ray induced production mechanisms are then re-examined, concluding that pulsars may be contributing significantly to the galactic gamma-ray emission.

  8. National Solar Radiation Data Bases (NSRDB): 1961 to 1990 and 1991 to 2005

    DOE Data Explorer

    The National Solar Radiation Data Base 1961-1990 (NSRDB) contains 30 years of solar radiation and supplementary meteorological data from 237 NWS sites in the U.S., plus sites in Guam and Puerto Rico. The updated 1991-2005 National Solar Radiation Database holds solar and meteorological data for 1,454 locations in the United States and its territories. See also the interactive data maps for the 1961 to 1990 data at http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/.

  9. A limited assessment and characterization of the solar radiation energy resources in the Caribbean region

    SciTech Connect

    Hulstrom, R.L.

    1988-02-01

    The objective of our work was to produce a preliminary assessment and characterization of the Caribbean region (Barbados, Dominican Republic, Guatemala, Jamaica, and Panama) solar radiation energy resources. Such information will be used to estimate the performance of, and identify the most promising applications of, solar heat technologies in the Caribbean region. We expect the solar radiation resources in the Caribbean region to be very location specific. Sunny areas will have an annual direct-beam resource of about 3,000 kWhm/sup /minus 2// and a global solar radiation resource of about 2,500 kWhm/sup /minus 2//. Cloud-covered areas will have annual solar radiation resources of about 1,500 kWhm/sup /minus 2/ for both the direct-beam and the global solar radiation. Monthly levels of solar radiaion will vary markedly, ranging from an average of 9 to 3 kWhm/sup /minus 2//day/sup /minus 1// for the direct-beam and from an average of 7 to 4 kWhm/sup /minus 2//day/sup /minus 1// for the global solar radiation. The Caribbean region is comparable to the Great Plains region of the US, in terms of annual solar radiation resources; however, thorough ''prospecting'' is required to avoid areas having very low amounts of solar radiation.

  10. Solar UV Radiation and the Origin of Life On Earth

    NASA Technical Reports Server (NTRS)

    Heap, S. R.; Lanz, T.; Hubeny, I.; Gaidos, E.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield and energy source for life. Here, we give a progress report on the first phase of this program to establish the UV radiation from the early Sun. We have obtained ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun We are making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. Once validated, these models will allow us to extrapolate our theoretical spectra to other metallicities and to unobserved spectral regions.

  11. Solar UV Radiation and the Origin of Life on Earth

    NASA Technical Reports Server (NTRS)

    Heap, S. R.; Gaidos, E.; Hubeny, I.; Lanz, T. M.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield, and energy source for life. Here, we give a progress report on the first phase of this program: to establish the UV radiation from the early Sun. We are presently obtaining ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun. We are currently making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. once validated, these models will allow us to extrapolate our theoretical spectra to unobserved spectral regions, and to proceed to the next step: to develop photochemical models of the pre-biotic and Archean atmosphere of the Earth.

  12. Determination of incoming solar radiation in major tree species in Turkey.

    PubMed

    Yilmaz, Osman Yalcin; Sevgi, Orhan; Koc, Ayhan

    2012-07-01

    Light requirements and spatial distribution of major forest tree species in Turkey hasn't been analyzed yet. Continuous surface solar radiation data, especially at mountainous-forested areas, are needed to put forward this relationship between forest tree species and solar radiation. To achieve this, GIS-based modeling of solar radiation is one of the methods used in rangelands to estimate continuous surface solar radiation. Therefore, mean monthly and annual total global solar radiation maps of whole Turkey were computed spatially using GRASS GIS software "r.sun" model under clear-sky (cloudless) conditions. 147498 pure forest stand point-based data were used in the study for calculating mean global solar radiation values of all the major forest tree species of Turkey. Beech had the lowest annual mean total global solar radiation value of 1654.87 kWh m(-2), whereas juniper had the highest value of 1928.89 kWh m(-2). The rank order of tree species according to the mean monthly and annual total global solar radiation values, using a confidence level of p < 0.05, was as follows: Beech < Spruce < Fir species < Oak species < Scotch pine < Red pine < Cedar < Juniper. The monthly and annual solar radiation values of sites and light requirements of forest trees ranked similarly. PMID:23360013

  13. Mathematical modeling and numerical analysis of thermal distribution in arch dams considering solar radiation effect.

    PubMed

    Mirzabozorg, H; Hariri-Ardebili, M A; Shirkhan, M; Seyed-Kolbadi, S M

    2014-01-01

    The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams.

  14. Mathematical Modeling and Numerical Analysis of Thermal Distribution in Arch Dams considering Solar Radiation Effect

    PubMed Central

    Mirzabozorg, H.; Hariri-Ardebili, M. A.; Shirkhan, M.; Seyed-Kolbadi, S. M.

    2014-01-01

    The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams. PMID:24695817

  15. Impact of Atmospheric Attenuations Time Resolutions in Solar Radiation Derived from Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Cony, Marco; Liria, Juan; Weisenberg, Ralf; Serrano, Enrique

    2014-05-01

    Accurate knowledge of solar irradiance components at the earth surface is of highly interest in many scientific and technology branches concerning meteorology, climate, agriculture and solar energy applications. In the specific case of solar energy systems the solar resource analysis with accuracy is a first step in every project since it is a required data for design, power output estimations, systems simulations and risk assessments. Solar radiation measurement availability is increasing both in spatial density and in historical archiving. However, it is still quite limited and most of the situations cannot make use of a long term ground database of high quality since solar irradiance is not generally measured where users need data. Satellite-derived solar radiation estimations are a powerful and valuable tool for solar resource assessment studies that have achieved a relatively high maturity due to years of developments and improvements. However, several sources of uncertainty are still present in satellite-derived methods. In particular, the strong influence of atmospheric attenuation information as input to the method is one of the main topics of improvement. Since solar radiation attenuation by atmospheric aerosols, and water vapor in a second place, is, after clouds, the second most important factor determining solar radiation, and particularly direct normal irradiance, the accurate knowledge of aerosol optical depth and water vapor content is relevant in the final output of satellite-derived methods. This present work, two different datasets we are used for extract atmospheric attenuation information. On the one hand the monthly mean values of the Linke turbidity factor from Meteotest database, which are twelve unique values of the Linke turbidity worldwide with a spatial resolution of 1/12º. On the other hand, daily values of AOD (Aerosol Optical Depth) at 550 nm, Angstrom alpha exponent and water vapor column were taken from a gridded database that

  16. Insolation data manual and direct normal solar radiation data manual

    SciTech Connect

    1990-07-01

    The Insolation Data Manual presents monthly averaged data which describes the availability of solar radiation at 248 National Weather Service (NWS) stations, principally in the United States. Monthly and annual average daily insolation and temperature values have been computed from a base of 24--25 years of data, generally from 1952--1975, and listed for each location. Insolation values represent monthly average daily totals of global radiation on a horizontal surface and are depicted using the three units of measurement: kJ/m{sup 2} per day, Btu/ft{sup 2} per day and langleys per day. Average daily maximum, minimum and monthly temperatures are provided for most locations in both Celsius and Fahrenheit. Heating and cooling degree-days were computed relative to a base of 18.3 C (65 F). For each station, global {bar K}{sub T} (cloudiness index) values were calculated on a monthly and annual basis. Global {bar K}{sub T} is an index of cloudiness and indicates fractional transmittance of horizontal radiation, from the top of the atmosphere to the earth's surface. The second section of this volume presents long-term monthly and annual averages of direct normal solar radiation for 235 NWS stations, including a discussion of the basic derivation process. This effort is in response to a generally recognized need for reliable direct normal data and the recent availability of 23 years of hourly averages for 235 stations. The relative inaccessibility of these data on microfiche further justifies reproducing at least the long-term averages in a useful format. In addition to a definition of terms and an overview of the ADIPA model, a discussion of model validation results is presented.

  17. Detailed modeling analysis for soot formation and radiation in microgravity gas jet diffusion flames

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, LI; Greenberg, Paul S.

    1995-01-01

    Radiation heat transfer in combustion systems has been receiving increasing interest. In the case of hydrocarbon fuels, a significant portion of the radiation comes from soot particles, justifying the need for detailed soot formation model and radiation transfer calculations. For laminar gas jet diffusion flames, results from this project (4/1/91 8/22/95) and another NASA study show that flame shape, soot concentration, and radiation heat fluxes are substantially different under microgravity conditions. Our emphasis is on including detailed soot transport models and a detailed solution for radiation heat transfer, and on coupling them with the flame structure calculations. In this paper, we will discuss the following three specific areas: (1) Comparing two existing soot formation models, and identifying possible improvements; (2) A simple yet reasonably accurate approach to calculating total radiative properties and/or fluxes over the spectral range; and (3) Investigating the convergence of iterations between the flame structure solver and the radiation heat transfer solver.

  18. Chapter 1.12: Solar Radiation Resource Assessment for Renewable Energy Conversion

    SciTech Connect

    Myers, D. R.

    2012-01-01

    This chapter addresses measurements, modeling, and databases of solar energy potential that may serve as fuel for solar energy conversion systems. Developing innovative designs for capturing and converting solar radiation is only one part of the equation for solar system deployment. Identifying, locating, and prospecting for the appropriate quantity and quality of solar resources to fuel these systems is critical to system designers, investors, financial backers, utilities, governments, and owner/operators. This chapter addresses the fundamentals and state of the art for measuring, modeling, and applying solar radiation resource data to meet decision-making needs.

  19. Total ozone column, aerosol optical depth and precipitable water effects on solar erythemal ultraviolet radiation recorded in Malta.

    NASA Astrophysics Data System (ADS)

    Bilbao, Julia; Román, Roberto; Yousif, Charles; Mateos, David; Miguel, Argimiro

    2013-04-01

    The Universities of Malta and Valladolid (Spain) developed a measurement campaign, which took place in the Institute for Energy Technology in Marsaxlokk (Southern Malta) between May and October 2012, and it was supported by the Spanish government through the Project titled "Measurement campaign about Solar Radiation, Ozone, and Aerosol in the Mediterranean area" (with reference CGL2010-12140-E). This campaign provided the first ground-based measurements in Malta of erythemal radiation and UV index, which indicate the effectiveness of the sun exposure to produce sunburn on human skin. A wide variety of instruments was involved in the campaign, providing a complete atmospheric characterization. Data of erythemal radiation and UV index (from UVB-1 pyranometer), total shortwave radiaton (global and diffuse components from CM-6B pyranometers), and total ozone column, aerosol optical thickness, and precitable water column (from a Microtops-II sunphotometer) were available in the campaign. Ground-based and satellite instruments were used in the analysis, and several intercomparisons were carried out to validate remote sensing data. OMI, GOME, GOME-2, and MODIS instruments, which provide data of ozone, aerosol load and optical properties, were used to this end. The effects on solar radiation, ultraviolet and total shortwave ranges, of total ozone column, aerosol optical thickness and precipitable water column were obtained using radiation measurements at different fixed solar zenith angles. The empirical results shown a determinant role of the solar position, a negligible effect of ozone on total shortwave radiation, and a stronger attenuation provided by aerosol particles in the erythemal radiation. A variety of aerosol types from different sources (desert dust, biomass burning, continental, and maritime) reach Malta, in this campaign several dust events from the Sahara desert occurred and were analyzed establishing the air mass back-trajectories ending at Malta at

  20. Implicit Solution of Non-Equilibrium Radiation Diffusion Including Reactive Heating Source in Material Energy Equation

    SciTech Connect

    Shumaker, D E; Woodward, C S

    2005-05-03

    In this paper, the authors investigate performance of a fully implicit formulation and solution method of a diffusion-reaction system modeling radiation diffusion with material energy transfer and a fusion fuel source. In certain parameter regimes this system can lead to a rapid conversion of potential energy into material energy. Accuracy in time integration is essential for a good solution since a major fraction of the fuel can be depleted in a very short time. Such systems arise in a number of application areas including evolution of a star and inertial confinement fusion. Previous work has addressed implicit solution of radiation diffusion problems. Recently Shadid and coauthors have looked at implicit and semi-implicit solution of reaction-diffusion systems. In general they have found that fully implicit is the most accurate method for difficult coupled nonlinear equations. In previous work, they have demonstrated that a method of lines approach coupled with a BDF time integrator and a Newton-Krylov nonlinear solver could efficiently and accurately solve a large-scale, implicit radiation diffusion problem. In this paper, they extend that work to include an additional heating term in the material energy equation and an equation to model the evolution of the reactive fuel density. This system now consists of three coupled equations for radiation energy, material energy, and fuel density. The radiation energy equation includes diffusion and energy exchange with material energy. The material energy equation includes reaction heating and exchange with radiation energy, and the fuel density equation includes its depletion due to the fuel consumption.

  1. Rapid formation of Jupiter by diffuse redistribution of water vapor in the solar nebula

    NASA Technical Reports Server (NTRS)

    Stevenson, David J.; Lunine, Jonathan I.

    1988-01-01

    In the present, water-vapor diffusive redistribution and condensation model of solid material abundance enhancement in the solar nebula's Jupiter-formation region, the assumed turbulent nebula temperatures decrease inversely with radial distance from the center, and time-scales are set by turbulent viscosities. The length scale for condensation of diffusively-transported water vapor is about 0.4 AU, and the surface density of ice in the Jupiter-formation zone undergoes enhancement by a factor of as much as 75; this surface density enhancement is enough to precipitate the rapid accretion of planetesimals into a solid core.

  2. On modeling the organization of landscapes and vegetation patterns controlled by solar radiation

    NASA Astrophysics Data System (ADS)

    Istanbulluoglu, E.; Yetemen, O.

    2014-12-01

    Solar radiation is a critical driver of ecohydrologic processes and vegetation dynamics. Patterns of runoff generation and vegetation dictate landscape geomorphic response. Distinct patterns in the organization of soil moisture, vegetation type, and landscape morphology have been documented in close relation to aspect in a range of climates. Within catchments, from north to south facing slopes, studies have shown ecotone shifts from forest to shrub species, and steep diffusion-dominated landforms to fluvial landforms. Over the long term differential evolution of ecohydrology and geomorphology leads to observed asymmetric structure in the planform of channel network and valley morphology. In this talk we present examples of coupled modeling of ecohydrology and geomorphology driven by solar radiation. In a cellular automata model of vegetation dynamics we will first show how plants organize in north and south facing slopes and how biodiversity changes with elevation. When vegetation-erosion feedbacks are coupled emergent properties of the coupled system are observed in the modeled elevation and vegetation fields. Integrating processes at a range of temporal and spatial scales, coupled models of ecohydrologic and geomorphic dynamics enable examination of global change impacts on landscapes and ecosystems.

  3. Exobiology at Southern Brazil: Spore Dosimetry and the UV Solar Radiation

    NASA Astrophysics Data System (ADS)

    Rampelotto, P. H.; Rosa, M. B.; Schuch, N. J.; Pinheiro, D. K.; Schuch, A. P.; Munakata, N.

    2009-12-01

    The ultraviolet - UV is considered the range of solar radiation most immediately lethal to the life organisms on the Earth’s surface. In this context, since 2000, the monitoring of the biologically-effective solar radiation using spore dosimeter at the Southern Space Observatory (29.4° S, 53.8° W), South of Brazil, has been performed. The biological dosimeter is based in the spore inactivation doses of Bacillus subtilis strain TKJ6312, who is sensitive to the UV solar radiation. Monthly expositions of biological dosimeter have been compared with solar irradiance obtained by Brewer spectrophotometer. Correlations indices about r > 0.86 shows the potential applicability of the biosensor in the monitoring of biologically-effective solar radiation. Since spores are stabile microorganisms, considering extreme environment variations, the biosensor may be used for studies of the effects of the solar radiation in others planetary environments for future work.

  4. Prediction of the solar radiation on the Earth using support vector regression technique

    NASA Astrophysics Data System (ADS)

    Piri, Jamshid; Shamshirband, Shahaboddin; Petković, Dalibor; Tong, Chong Wen; Rehman, Muhammad Habib ur

    2015-01-01

    The solar rays on the surface of Earth is one of the major factor in water resources, environmental and agricultural modeling. The main environmental factors influencing plants growth are temperature, moisture, and solar radiation. Solar radiation is rarely obtained in weather stations; as a result, many empirical approaches have been applied to estimate it by using other parameters. In this study, a soft computing technique, named support vector regression (SVR) has been used to estimate the solar radiation. The data was collected from two synoptic stations with different climate conditions (Zahedan and Bojnurd) during the period of 5 and 7 years, respectively. These data contain sunshine hours, maximum temperature, minimum temperature, average relative humidity and daily solar radiation. In this study, the polynomial and radial basis functions (RBF) are applied as the SVR kernel function to estimate solar radiation. The performance of the proposed estimators is confirmed with the simulation results.

  5. Verification of Mars solar radiation model based on Mars Pathfinder data

    SciTech Connect

    Appelbaum, J.; Segalov, T.; Jenkins, P.P.; Landis, G.A.; Baraona, C.R.

    1997-12-31

    The solar radiation model for the Martian surface was developed based on the images taken by the two Viking Landers VL1 and VL2 cameras, and calculation of the solar flux function. This model was used for the design of the Pathfinder`s photovoltaic arrays. The Pathfinder is equipped with various instruments capable of measuring data from which solar radiation quantities may be derived. In the present study the authors use data of the Lander and Rover, and perform correlation calculation to the solar radiation model. This study shows that the solar radiation model predicts with good accuracy the solar radiation on the Martian surface for horizontal photovoltaic arrays and for an optical depth of 0.5 of the Martian atmosphere.

  6. Radiation response of multi-quantum well solar cells: Electron-beam-induced current analysis

    NASA Astrophysics Data System (ADS)

    Maximenko, S. I.; Lumb, M. P.; Hoheisel, R.; Gonzalez, M.; Scheiman, D. A.; Messenger, S. R.; Tibbits, T. N. D.; Imaizumi, M.; Ohshima, T.; Sato, S. I.; Jenkins, P. P.; Walters, R. J.

    2015-12-01

    Solar cells utilizing multi-quantum well (MQW) structures are considered promising candidate materials for space applications. An open question is how well these structures can resist the impact of particle irradiation. The aim of this work is to provide feedback about the radiation response of In0.01Ga0.99As solar cells grown on Ge with MQWs incorporated within the i-region of the device. In particular, the local electronic transport properties of the MQW i-regions of solar cells subjected to electron and proton irradiation were evaluated experimentally using the electron beam induced current (EBIC) technique. The change in carrier collection distribution across the MQW i-region was analyzed using a 2D EBIC diffusion model in conjunction with numerical modeling of the electrical field distribution. Both experimental and simulated findings show carrier removal and type conversion from n- to p-type in MQW i-region at a displacement damage dose as low as ˜6.06-9.88 × 109 MeV/g. This leads to a redistribution of the electric field and significant degradation in charge carrier collection.

  7. Radiation response of multi-quantum well solar cells: Electron-beam-induced current analysis

    SciTech Connect

    Maximenko, S. I. Scheiman, D. A.; Jenkins, P. P.; Walters, R. J.; Lumb, M. P.; Hoheisel, R.; Gonzalez, M.; Messenger, S. R.; Tibbits, T. N. D.; Imaizumi, M.; Ohshima, T.; Sato, S. I.

    2015-12-28

    Solar cells utilizing multi-quantum well (MQW) structures are considered promising candidate materials for space applications. An open question is how well these structures can resist the impact of particle irradiation. The aim of this work is to provide feedback about the radiation response of In{sub 0.01}Ga{sub 0.99}As solar cells grown on Ge with MQWs incorporated within the i-region of the device. In particular, the local electronic transport properties of the MQW i-regions of solar cells subjected to electron and proton irradiation were evaluated experimentally using the electron beam induced current (EBIC) technique. The change in carrier collection distribution across the MQW i-region was analyzed using a 2D EBIC diffusion model in conjunction with numerical modeling of the electrical field distribution. Both experimental and simulated findings show carrier removal and type conversion from n- to p-type in MQW i-region at a displacement damage dose as low as ∼6.06–9.88 × 10{sup 9} MeV/g. This leads to a redistribution of the electric field and significant degradation in charge carrier collection.

  8. Calculation of Solar Radiation by Using Regression Methods

    NASA Astrophysics Data System (ADS)

    Kızıltan, Ö.; Şahin, M.

    2016-04-01

    In this study, solar radiation was estimated at 53 location over Turkey with varying climatic conditions using the Linear, Ridge, Lasso, Smoother, Partial least, KNN and Gaussian process regression methods. The data of 2002 and 2003 years were used to obtain regression coefficients of relevant methods. The coefficients were obtained based on the input parameters. Input parameters were month, altitude, latitude, longitude and landsurface temperature (LST).The values for LST were obtained from the data of the National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR) satellite. Solar radiation was calculated using obtained coefficients in regression methods for 2004 year. The results were compared statistically. The most successful method was Gaussian process regression method. The most unsuccessful method was lasso regression method. While means bias error (MBE) value of Gaussian process regression method was 0,274 MJ/m2, root mean square error (RMSE) value of method was calculated as 2,260 MJ/m2. The correlation coefficient of related method was calculated as 0,941. Statistical results are consistent with the literature. Used the Gaussian process regression method is recommended for other studies.

  9. Detection of atmospheric Cherenkov radiation using solar heliostat mirrors

    NASA Astrophysics Data System (ADS)

    Ong, R. A.; Bhattacharya, D.; Covault, C. E.; Dixon, D. D.; Gregorich, D. T.; Hanna, D. S.; Oser, S.; Québert, J.; Smith, D. A.; Tümer, O. T.; Zych, A. D.

    1996-10-01

    There is considerable interest world-wide in developing large area atmospheric Cherenkov detectors for ground-based gamma-ray astronomy. This interest stems, in large part, from the fact that the gamma-ray energy region between 20 and 250 GeV is unexplored by any experiment. Atmospheric Cherenkov detectors offer a possible way to explore this region, but large photon collection areas are needed to achieve low energy thresholds. We are developing an experiment using the heliostat mirrors of a solar power plant as the primary collecting element. As part of this development, we built a detector using four heliostat mirrors, a secondary Fresnel lens, and a fast photon detection system. In November 1994, we used this detector to record atmospheric Cherenkov radiation produced by cosmic ray particles showering in the atmosphere. The detected rate of cosmic ray events was consistent with an energy threshold near 1 TeV. The data presented here represent the first detection of atmospheric Cherenkov radiation using solar heliostats viewed from a central tower.

  10. NEW HIGHER PERFORMANCE LOW COST SELECTIVE SOLAR RADIATION CONTROL COATINGS

    SciTech Connect

    Timothy Ellison; Buddie Dotter; David Tsu

    2003-10-28

    Energy Conversion Devices, Inc., ECD, has developed a new high-speed low-cost process for depositing high quality dielectric optical coatings--Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD). This process can deposit SiO{sub x} about 10 times faster than the state-of-the-art conventional technology, magnetron sputtering, at about 1/10th the cost. This process is also being optimized for depositing higher refractive index materials such as Si{sub 3}N{sub 4} and TiO{sub 2}. In this program ECD, in collaboration with Southwall Technologies, Inc. (STI), demonstrated that this process can be used to fabricate high performance low cost Selective Solar Radiation Control (SSRC) films for use in the automotive industry. These coatings were produced on thin (2 mil thick) PET substrates in ECD's pilot roll-to-roll pilot MPECVD deposition machine. Such film can be laminated with PVB in a vehicle's windows. This process can also be used to deposit the films directly onto the glass. Such highly selective films, with a visible transmission (T{sub vis}) of > 70% and a shading coefficient of < 60% can significantly reduce the heat entering a car from solar radiation. Consequently, passenger comfort is increased and the energy needed to operate air conditioning (a/c) systems is reduced; consequently smaller a/c systems can be employed resulting in improved vehicle fuel efficiency.

  11. GaAs quantum dot solar cell under concentrated radiation

    SciTech Connect

    Sablon, K.; Little, J. W.; Hier, H.; Li, Y.; Mitin, V.; Vagidov, N.; Sergeev, A.

    2015-08-17

    Effects of concentrated solar radiation on photovoltaic performance are investigated in well-developed GaAs quantum dot (QD) solar cells with 1-Sun efficiencies of 18%–19%. In these devices, the conversion processes are enhanced by nanoscale potential barriers and/or AlGaAs atomically thin barriers around QDs, which prevent photoelectron capture to QDs. Under concentrated radiation, the short circuit current increases proportionally to the concentration and the open circuit voltage shows the logarithmic increase. In the range up to hundred Suns, the contributions of QDs to the photocurrent are proportional to the light concentration. The ideality factors of 1.1–1.3 found from the V{sub OC}-Sun characteristics demonstrate effective suppression of recombination processes in barrier-separated QDs. The conversion efficiency shows the wide maximum in the range of 40–90 Suns and reaches 21.6%. Detailed analysis of I-V-Sun characteristics shows that at low intensities, the series resistance decreases inversely proportional to the concentration and, at ∼40 Suns, reaches the plateau determined mainly by the front contact resistance. Improvement of contact resistance would increase efficiency to above 24% at thousand Suns.

  12. A solar radiation model for use in climate studies

    SciTech Connect

    Chou, M.D. )

    1992-05-01

    A solar radiation routine has been developed for use in climate studies. It includes the absorption and scattering due to ozone, water vapor, oxygen, carbon dioxide, clouds, and aerosols. Rayleigh scattering is also included. The UV and visible region ([lambda] < 0.69 [mu]m) is grouped into four bands. An effective coefficient for ozone absorption and an effective cross section for Rayleigh scattering are computed for each band. In the near-infrared region ([lambda] > 0.69 [mu]m), the broadband parameterization is used to compute the absorption by water vapor in a clear atmosphere, and the k-distribution method is applied to compute fluxes in a scattering atmosphere. The reflectivity and transmissivity of a scattering layer are computed analytically using the delta-four-stream discrete-ordinate approximation. The two-stream adding method is then applied to compute fluxes for a composite of clear and scattering layers. Compared to the results of high spectral resolution and detailed multiple-scattering calculations, fluxes and heating rate are accurately computed to within a few percent. The high accuracy of flux and heating rate calculations is achieved with a reasonable amount of computing time. With the UV and visible region grouped into four bands, this solar radiation routine is useful not only for climate but also for studies on the photolysis in the upper atmosphere and the photosynthesis in the biosphere. 19 refs., 6 figs., 6 tabs.

  13. Effects of increased solar ultraviolet radiation on materials.

    PubMed

    Andrady, A L; Hamid, S H; Hu, X; Torikai, A

    1998-10-01

    Synthetic polymers such as plastics, as well as naturally occurring polymer materials such as wood, are extensively used in building construction and other outdoor applications where they are routinely exposed to sunlight. The UV-B content in sunlight is well known to affect adversely the mechanical properties of these materials, limiting their useful life. Presently their outdoor lifetimes depend on the use of photostabilizers in the case of plastics and on protective surface coatings in the case of wood. Any increase in the solar UV-B content due to a partial ozone depletion would therefore tend to decrease the outdoor service life of these materials. It is the synergistic effect of increased UV radiation with other factors such as the temperature that would determine the extent of such reduction in service life. The increased cost associated with such a change would be felt unevenly across the globe. Those developing countries that depend on plastics as a prime material of construction and experience high ambient temperatures are likely to be particularly affected in spite of the relatively small fractional decrease in ozone at those locations. Assessment of the damage to materials, associated with ozone depletion, requires a knowledge of the wavelength dependence as well as the dose-response characteristics of the polymer degradation processes of interest. While the recent literature includes some reliable spectral sensitivity data, little dose-response information has been reported, so it is difficult to make such assessments reliably at the present time. This is particularly true for the naturally occurring materials popularly used in construction applications. To maintain polymers at the same useful lifetime in spite of increased solar UV-B content, the amount of photostabilizers used in the formulations might be increased. This strategy assumes that conventional stabilizers will continue to be effective with the spectrally altered UV-B-enhanced solar

  14. Simplified calibration for broadband solar ultraviolet radiation measurements.

    PubMed

    Oppenrieder, A; Hoeppe, P; Koepke, P; Reuder, J; Schween, J; Schreder, J

    2003-12-01

    Aspects of different calibration procedures for erythemally weighing broadband radiometers are presented in this study. These instruments are common in projects dealing with ultraviolet radiation effects on humans. Many erythemally weighing broadband radiometers are still operated using a single calibration factor (cf) that is provided with the instrument. The individual characteristics of every instrument are strongly dependent on the total ozone amount and the solar elevation. Therefore, a calibration procedure also has to take into account the ozone concentrations and the solar elevation to compensate for the effects of the individual characteristics and to provide comparable measurements. Given the variation of the ozone concentrations and the solar elevation, an individual cf has to be calculated for every measurement. Using a simplified version of the calibration procedure, which is presented in this study, can lessen this effort. Taking into account the relevant meteorological conditions for a measuring site, a single cf is calculated to compensate the individual characteristics of the instruments and therefore deliver comparable measurements with less effort. PMID:14743870

  15. Division II: Commission 12: Solar Radiation and Structure

    NASA Astrophysics Data System (ADS)

    Kosovichev, Alexander; Cauzzi, Gianna; Pillet, Valentin Martinez; Asplund, Martin; Brandenburg, Axel; Chou, Dean-Yi; Christensen-Dalsgaard, Jorgen; Gan, Weiqun; Kuznetsov, Vladimir D.; Rovira, Marta G.; Shchukina, Nataliya; Venkatakrishnan, P.

    2015-08-01

    The President of C12, Alexander Kosovichev, presented the status of the Commission and its working Group(s). Primary activities included organization of international meetings (IAU Symposia, Special Sessions and Joint Discussion); review and support of proposals for IAU sponsored meetings; organization of working groups on the Commission topics to promote the international cooperation; preparation of triennial report on the organizational and science activities of Commission members. Commission 12 broadly encompasses topics of solar research which include studies of the Sun's internal structure, composition, dynamics and magnetism (through helioseismology and other techniques), studies of the quiet photosphere, chromosphere and corona, and also research of the mechanisms of solar radiation, and its variability on various time scales. Some overlap with topics covered by Commission 10 Solar Activity is unavoidable, and many activities are sponsored jointly by these two commissions. The Commission website can be found at http://sun.stanford.edu/IAU-Com12/, with information about related IAU Symposiums and activities, and links to appropriate web sites.

  16. Effect of solar radiation on the migration of vinyl chloride monomer from unplasticized PVC pipes.

    PubMed

    Al-Malack, M H; Sheikheldin, S Y

    2001-10-01

    The effect of direct exposure to solar radiation on the migration of vinyl chloride monomer (VCM) from unplasticized polyvinyl chloride (uPVC) pipes was investigated using locally manufactured and imported pipes. Specimens 33 cm long were used throughout the research. The investigation was carried out, at different times of exposure, by exposing one part of the specimens to the direct sunlight, while keeping the other part in the shade. The VCM concentration in the water was evaluated using the gas chromatography (GC)/head-space technique. A VCM concentration of 2.5 microg/l was detected after 30 days of exposure in direct sunlight. The original initial VCM concentration in the uPVC was predicted, and the diffusion rate of VCM from uPVC pipes was expressed as a function of time.

  17. Modeling influences of topography on incoming solar radiation from satellite remote sensing data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria

    2007-08-01

    Solar radiation is the primary source of energy that drives earth system processes, such as weather patterns and rates of primary production by green plants. Accurate solar irradiance data are necessary for the radiative forcing of the climate system assessment as well as for efficient planning and operation of solar energy systems. Topography is a major factor that determines the amount of solar radiation reaching any particular location on the Earth's surface. Its variability in elevation, surface orientation (slope and aspect), and shadows is subject to quantitative modeling, based on radiative transfer models (RTM) using atmospheric parameter information retrieved from the MODIS satellites. This paper focuses on the description of a solar radiation model to describe spatial and temporal patterns of daily radiation based on topography and daily temperature regimes with a specific analysis for Dobruja area, Romania.

  18. Using hybrid implicit Monte Carlo diffusion to simulate gray radiation hydrodynamics

    SciTech Connect

    Cleveland, Mathew A. Gentile, Nick

    2015-06-15

    This work describes how to couple a hybrid Implicit Monte Carlo Diffusion (HIMCD) method with a Lagrangian hydrodynamics code to evaluate the coupled radiation hydrodynamics equations. This HIMCD method dynamically applies Implicit Monte Carlo Diffusion (IMD) [1] to regions of a problem that are opaque and diffusive while applying standard Implicit Monte Carlo (IMC) [2] to regions where the diffusion approximation is invalid. We show that this method significantly improves the computational efficiency as compared to a standard IMC/Hydrodynamics solver, when optically thick diffusive material is present, while maintaining accuracy. Two test cases are used to demonstrate the accuracy and performance of HIMCD as compared to IMC and IMD. The first is the Lowrie semi-analytic diffusive shock [3]. The second is a simple test case where the source radiation streams through optically thin material and heats a thick diffusive region of material causing it to rapidly expand. We found that HIMCD proves to be accurate, robust, and computationally efficient for these test problems.

  19. Using hybrid implicit Monte Carlo diffusion to simulate gray radiation hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cleveland, Mathew A.; Gentile, Nick

    2015-06-01

    This work describes how to couple a hybrid Implicit Monte Carlo Diffusion (HIMCD) method with a Lagrangian hydrodynamics code to evaluate the coupled radiation hydrodynamics equations. This HIMCD method dynamically applies Implicit Monte Carlo Diffusion (IMD) [1] to regions of a problem that are opaque and diffusive while applying standard Implicit Monte Carlo (IMC) [2] to regions where the diffusion approximation is invalid. We show that this method significantly improves the computational efficiency as compared to a standard IMC/Hydrodynamics solver, when optically thick diffusive material is present, while maintaining accuracy. Two test cases are used to demonstrate the accuracy and performance of HIMCD as compared to IMC and IMD. The first is the Lowrie semi-analytic diffusive shock [3]. The second is a simple test case where the source radiation streams through optically thin material and heats a thick diffusive region of material causing it to rapidly expand. We found that HIMCD proves to be accurate, robust, and computationally efficient for these test problems.

  20. Large solar flare radiation shielding requirements for manned interplanetary missions.

    PubMed

    Townsend, L W; Nealy, J E; Wilson, J W; Atwell, W

    1989-01-01

    As the 21st century approaches, there is an ever-increasing interest in launching manned missions to Mars. A major concern to mission planners is exposure of the flight crews to highly penetrating and damaging space radiations. Beyond the protective covering of the Earth's magnetosphere, the two main sources of these radiations are galactic cosmic rays and solar particle events. Preliminary analyses of potential exposures from galactic cosmic rays (GCR's) were presented elsewhere. In this Note, estimates of shielding thicknesses required to protect astronauts on interplanetary missions from the effects of large solar flare events are presented. The calculations use integral proton fluences for the February 1956, November 1960, and August 1972 solar particle events as inputs into the NASA Langley Research Center nucleon transport code BRYNTRN. This deterministic computer code transports primary protons and secondary protons and neutrons through any number of layers of target material of arbitrary thickness and composition. Contributions from target nucleus breakup (fragmentation) and recoil are also included. The results for each flare are presented as estimates of dose equivalent [in units of roentgen equivalent man (rem)] to the skin, eye, and bloodforming organs (BFO) behind various thicknesses of aluminum shielding. These results indicate that the February 1956 event was the most penetrating; however, the August 1972 event, the largest ever recorded, could have been mission- or life-threatening for thinly shielded (< or = 5 g/cm2) spacecraft. Also presented are estimates of the thicknesses of water shielding required to reduce the BFO dose equivalent to currently recommended astronaut exposure limits. These latter results suggest that organic polymers, similar to water, appear to be a much more desirable shielding material than aluminum. PMID:11537157

  1. Diffusion-Reaction Modeling of Cu Migration in CdTe Solar Devices

    SciTech Connect

    Guo, Da; Brinkman, Daniel; Fang, Tian; Akis, Richard; Sankin, Igor; Vasileska, Dragica; Ringhofer, Christian

    2015-09-04

    In this work, we report on development of one-dimensional (1D) finite-difference and two-dimensional (2D) finite-element diffusion-reaction simulators to investigate mechanisms behind Cu-related metastabilities observed in CdTe solar cells [1]. The evolution of CdTe solar cells performance has been studied as a function of stress time in response to the evolution of associated acceptor and donor states. To achieve such capability, the simu-lators solve reaction-diffusion equations for the defect states in time-space domain self-consistently with the free carrier transport. Re-sults of 1-D and 2-D simulations have been compared to verify the accuracy of solutions.

  2. Characterization of Flexible CIGS Thin Film Solar Cells or Stainless Steel with Intrinsic ZnO Diffusion Barriers.

    PubMed

    Kim, Chae-Woong; Kim, Hye Jin; Kim, Jin Hyeok; Jeong, Chaehwan

    2016-05-01

    ZnO diffusion barrier layer was deposited by RF magnetron sputtering by using the same method as intrinsic ZnO layer. The CIGS solar cells were fabricated on stainless steel substrate. The 50-200 nm thin ZnO diffusion barriers effectively reduced the diffusion of Fe and Cr, from stainless steel substrates into the CIGS absorbers. The CIGS solar cells with ZnO diffusion barriers increased the J(sc) and FF, which resulted in an increase of cell efficiency from 5.9% up to 9.06%. PMID:27483885

  3. Socio-economic and communication factors influencing the diffusion of solar-energy equipment among California homeowners

    SciTech Connect

    Mbindyo, J.M.

    1981-01-01

    This dissertation explores the influence of socio-economic, communication, and social-psychological factors on the diffusion of solar-energy equipment among California homeowners. There were four specific objectives: (1) to critique previous studies on the diffusion of solar technology; (2) to critique fundamental aspects of current diffusion models and to formulate an alternative diffusion perspective; (3) to use the proposed theoretical perspective to predict solar diffusion; and (4) to test certain of the proposed predictions about solar diffusion. Data used to test some of the predictions were based on a state-wide random survey of 812 California homeowners. The dissertation presents two major findings. First, some of the best predictors of the solar-diffusion process were found to be age, socio-economic status, knowing solar owners, ownership of a swimming pool, utility costs, efficacy towards the energy situation, voluntary simplicity, energy consciousness, community size, and perceived community interest in solar. Second, these predictors were found to be strongly related to socio-economic status. The present study argues that these predictors are in fact post indicators of socio-economic status. Thus, whereas many of the previous studies tended to underestimate the influence of socio-economic factors, this study was able to demonstrate the crucial influence of socio-economic factors in determining the rate and pattern of solar diffusion. The data show that household solar-energy equipment is basically an innovation for high and medium socio-economic groups. The implications of these findings with regard to previous studies, policy, and future research are also discussed.

  4. Photovoltaic characteristics of diffused P/+N bulk GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Borrego, J. M.; Keeney, R. P.; Bhat, I. B.; Bhat, K. N.; Sundaram, L. G.; Ghandhi, S. K.

    1982-01-01

    The photovoltaic characteristics of P(+)N junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are described in this paper.Spectral response measurements were analyzed in detail and compared to a computer simulation in order to determine important material parameters. It is projected that proper optimization of the cell parameters can increase the efficiency of the cells from 12.2 percent to close to 20 percent.

  5. Broken-cloud enhancement of solar radiation absorption

    SciTech Connect

    Byrne, R.N.; Somerville, R.C.; Subasilar, B.

    1996-04-01

    Two papers recently published in Science have shown that there is more absorption of solar radiation than estimated by current atmospheric general circulation models (GCMs) and that the discrepancy is associated with cloudy scenes. We have devised a simple model which explains this as an artifact of stochastic radiative transport. We first give a heuristic description, unencumbered by mathematical detail. Consider a simple case with clouds distributed at random within a single level whose upper and lower boundaries are fixed. The solar zenith angle is small to moderate; this is therefore an energetically important case. Fix the average areal liquid water content of the cloud layer, and take the statistics of the cloud distribution to be homogeneous within the layer. Furthermore, assume that all the clouds in the layer have the same liquid water content, constant throughout the cloud, and that apart from their droplet content they are identical to the surrounding clear sky. Let the clouds occupy on the average a fraction p{sub cld} of the volume of the cloudy layer, and let them have a prescribed distribution of sizes about some mean. This is not a fractal distribution, because it has a scale. Cloud shape is unimportant so long as cloud aspect ratios are not far from unity. Take the single-scattering albedo to be unity for the droplets in the clouds. All of the absorption is due to atmospheric gases, so the absorption coefficient at a point is the same for cloud and clear sky. Absorption by droplets is less than 10% effect in the numerical stochastic radiation calculations described below, so it is reasonable to neglect it at this level of idealization.

  6. Solar Radiation Measurements Onboard the Research Aircraft HALO

    NASA Astrophysics Data System (ADS)

    Lohse, I.; Bohn, B.; Werner, F.; Ehrlich, A.; Wendisch, M.

    2014-12-01

    Airborne measurements of the separated upward and downward components of solar spectral actinic flux densities for the determination of photolysis frequencies and of upward nadir spectral radiance were performed with the HALO Solar Radiation (HALO-SR) instrument package onboard the High Altitude and Long Range Research Aircraft (HALO). The instrumentation of HALO-SR is characterized and first measurement data from the Next-generation Aircraft Remote-Sensing for Validation Studies (NARVAL) campaigns in 2013 and 2014 are presented. The measured data are analyzed in the context of the retrieved microphysical and optical properties of clouds which were observed underneath the aircraft. Detailed angular sensitivities of the two optical actinic flux receivers were determined in the laboratory. The effects of deviations from the ideal response are investigated using radiative transfer calculations of atmospheric radiance distributions under various atmospheric conditions and different ground albedos. Corresponding correction factors are derived. Example photolysis frequencies are presented, which were sampled in the free troposphere and lower stratosphere over the Atlantic Ocean during the 2013/14 HALO NARVAL campaigns. Dependencies of photolysis frequencies on cloud cover, flight altitude and wavelength range of the photolysis process are investigated. Calculated actinic flux densities in the presence of clouds benefit from the measured spectral radiances. Retrieved cloud optical thicknesses and effective droplet radii are used as model input for the radiative transfer calculations. By comparison with the concurrent measurements of actinic flux densities the retrieval approach is validated. Acknowledgements: Funding by the Deutsche Forschungsgemeinschaft within the priority program HALO (BO 1580/4-1, WE 1900/21-1) is gratefully acknowledged.

  7. Influence of diffusion on photoinduced electron transfer. [laser radiation

    SciTech Connect

    Song, L.; Dorfman, R.C.; Swallen, S.F.; Fayer, M.D. )

    1991-05-02

    Electron transfer from an optically excited donor (rubrene) to randomly distributed acceptors (duroquinone) has been investigated experimentally. The forward electron-transfer process under the influence of diffusion in liquid solution (diethyl sebacate) is compared with that in solid solution (sucrose octaacetate). Steady-state fluorescence yield and time-resolved fluorescence measurements were used to measure the excited-state population of the donor (rubrene). The parameters were used to analyze the electron-transfer dynamics under a variety of acceptor concentrations. The agreement between theoretical predictions and experiments is very good. The forward transfer parameters (a{sub f} and R{sub 0}) in liquid solution are almost identical with those obtained in solid solution.

  8. Predictability of Solar Radiation for Photovoltaics systems over Europe: from short-term to seasonal time-scales

    NASA Astrophysics Data System (ADS)

    De Felice, Matteo; Petitta, Marcello; Ruti, Paolo

    2014-05-01

    Photovoltaic diffusion is steadily growing on Europe, passing from a capacity of almost 14 GWp in 2011 to 21.5 GWp in 2012 [1]. Having accurate forecast is needed for planning and operational purposes, with the possibility to model and predict solar variability at different time-scales. This study examines the predictability of daily surface solar radiation comparing ECMWF operational forecasts with CM-SAF satellite measurements on the Meteosat (MSG) full disk domain. Operational forecasts used are the IFS system up to 10 days and the System4 seasonal forecast up to three months. Forecast are analysed considering average and variance of errors, showing error maps and average on specific domains with respect to prediction lead times. In all the cases, forecasts are compared with predictions obtained using persistence and state-of-art time-series models. We can observe a wide range of errors, with the performance of forecasts dramatically affected by orography and season. Lower errors are on southern Italy and Spain, with errors on some areas consistently under 10% up to ten days during summer (JJA). Finally, we conclude the study with some insight on how to "translate" the error on solar radiation to error on solar power production using available production data from solar power plants. [1] EurObserver, "Baromètre Photovoltaïque, Le journal des énergies renouvables, April 2012."

  9. Sensitivity analysis of numerical weather prediction radiative schemes to forecast direct solar radiation over Australia

    NASA Astrophysics Data System (ADS)

    Mukkavilli, S. K.; Kay, M. J.; Taylor, R.; Prasad, A. A.; Troccoli, A.

    2014-12-01

    The Australian Solar Energy Forecasting System (ASEFS) project requires forecasting timeframes which range from nowcasting to long-term forecasts (minutes to two years). As concentrating solar power (CSP) plant operators are one of the key stakeholders in the national energy market, research and development enhancements for direct normal irradiance (DNI) forecasts is a major subtask. This project involves comparing different radiative scheme codes to improve day ahead DNI forecasts on the national supercomputing infrastructure running mesoscale simulations on NOAA's Weather Research & Forecast (WRF) model. ASEFS also requires aerosol data fusion for improving accurate representation of spatio-temporally variable atmospheric aerosols to reduce DNI bias error in clear sky conditions over southern Queensland & New South Wales where solar power is vulnerable to uncertainities from frequent aerosol radiative events such as bush fires and desert dust. Initial results from thirteen years of Bureau of Meteorology's (BOM) deseasonalised DNI and MODIS NASA-Terra aerosol optical depth (AOD) anomalies demonstrated strong negative correlations in north and southeast Australia along with strong variability in AOD (~0.03-0.05). Radiative transfer schemes, DNI and AOD anomaly correlations will be discussed for the population and transmission grid centric regions where current and planned CSP plants dispatch electricity to capture peak prices in the market. Aerosol and solar irradiance datasets include satellite and ground based assimilations from the national BOM, regional aerosol researchers and agencies. The presentation will provide an overview of this ASEFS project task on WRF and results to date. The overall goal of this ASEFS subtask is to develop a hybrid numerical weather prediction (NWP) and statistical/machine learning multi-model ensemble strategy that meets future operational requirements of CSP plant operators.

  10. IPR 1.0: an efficient method for calculating solar radiation absorbed by individual plants in sparse heterogeneous woody plant communities

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Chen, W.; Li, J.

    2013-12-01

    Climate change may alter the spatial distribution, composition, structure, and functions of plant communities. Transitional zones between biomes, or ecotones, are particularly sensitive to climate change. Ecotones are usually heterogeneous with sparse trees. The dynamics of ecotones are mainly determined by the growth and competition of individual plants in the communities. Therefore it is necessary to calculate solar radiation absorbed by individual plants for understanding and predicting their responses to climate change. In this study, we developed an individual plant radiation model, IPR (version 1.0), to calculate solar radiation absorbed by individual plants in sparse heterogeneous woody plant communities. The model is developed based on geometrical optical relationships assuming crowns of woody plants are rectangular boxes with uniform leaf area density. The model calculates the fractions of sunlit and shaded leaf classes and the solar radiation absorbed by each class, including direct radiation from the sun, diffuse radiation from the sky, and scattered radiation from the plant community. The solar radiation received on the ground is also calculated. We tested the model by comparing with the analytical solutions of random distributions of plants. The tests show that the model results are very close to the averages of the random distributions. This model is efficient in computation, and is suitable for ecological models to simulate long-term transient responses of plant communities to climate change.

  11. Prediction of hourly and daily diffuse solar fraction in the city of Fez (Morocco)

    NASA Astrophysics Data System (ADS)

    Ihya, B.; Mechaqrane, A.; Tadili, R.; Bargach, M. N.

    2015-05-01

    In this paper, 3-layers MLP (Multi-Layers Perceptron) Artificial Neural Network (ANN) models have been developed and tested for predicting hourly and daily diffuse solar fractions at Fez city in Morocco. In parallel, some empirical models were tested. Three years of data (2009-2011) have been used for establishing the parameters of all tested models and 1 year (2012) to test their prediction performances. To select the best ANN (3-layers MLP) architecture, we have conducted several tests by using different combinations of inputs and by varying the number of neurons in the hidden layer. The output is only the diffuse solar fraction. The performances of each model were assessed on the basis of four statistic characteristics: mean absolute error (MAE), relative mean bias error (RMBE), relative root mean square error (RRMSE) and the degree of agreement (DA). Additionally, the coefficient of correlation ( R) is used to test the linear regression between predicted and observed data. The results indicate that the ANN model is more suitable for predicting diffuse solar fraction than the empirical tested models at Fez city in Morocco.

  12. Uncertainty in assessment of radiation-induced diffusion index changes in individual patients

    NASA Astrophysics Data System (ADS)

    Nazem-Zadeh, Mohammad-Reza; Chapman, Christopher H.; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue

    2013-06-01

    The purpose of this study is to evaluate repeatability coefficients of diffusion tensor indices to assess whether longitudinal changes in diffusion indices were true changes beyond the uncertainty for individual patients undergoing radiation therapy (RT). Twenty-two patients who had low-grade or benign tumors and were treated by partial brain radiation therapy (PBRT) participated in an IRB-approved MRI protocol. The diffusion tensor images in the patients were acquired pre-RT, week 3 during RT, at the end of RT, and 1, 6, and 18 months after RT. As a measure of uncertainty, repeatability coefficients (RC) of diffusion indices in the segmented cingulum, corpus callosum, and fornix were estimated by using test-retest diffusion tensor datasets from the National Biomedical Imaging Archive (NBIA) database. The upper and lower limits of the 95% confidence interval of the estimated RC from the test and retest data were used to evaluate whether the longitudinal percentage changes in diffusion indices in the segmented structures in the individual patients were beyond the uncertainty and thus could be considered as true radiation-induced changes. Diffusion indices in different white matter structures showed different uncertainty ranges. The estimated RC for fractional anisotropy (FA) ranged from 5.3% to 9.6%, for mean diffusivity (MD) from 2.2% to 6.8%, for axial diffusivity (AD) from 2.4% to 5.5%, and for radial diffusivity (RD) from 2.9% to 9.7%. Overall, 23% of the patients treated by RT had FA changes, 44% had MD changes, 50% had AD changes, and 50% had RD changes beyond the uncertainty ranges. In the fornix, 85.7% and 100% of the patients showed changes beyond the uncertainty range at 6 and 18 months after RT, demonstrating that radiation has a pronounced late effect on the fornix compared to other segmented structures. It is critical to determine reliability of a change observed in an individual patient for clinical decision making. Assessments of the repeatability and

  13. Uncertainty in assessment of radiation-induced diffusion index changes in individual patients.

    PubMed

    Nazem-Zadeh, Mohammad-Reza; Chapman, Christopher H; Lawrence, Theodore S; Tsien, Christina I; Cao, Yue

    2013-06-21

    The purpose of this study is to evaluate repeatability coefficients of diffusion tensor indices to assess whether longitudinal changes in diffusion indices were true changes beyond the uncertainty for individual patients undergoing radiation therapy (RT). Twenty-two patients who had low-grade or benign tumors and were treated by partial brain radiation therapy (PBRT) participated in an IRB-approved MRI protocol. The diffusion tensor images in the patients were acquired pre-RT, week 3 during RT, at the end of RT, and 1, 6, and 18 months after RT. As a measure of uncertainty, repeatability coefficients (RC) of diffusion indices in the segmented cingulum, corpus callosum, and fornix were estimated by using test-retest diffusion tensor datasets from the National Biomedical Imaging Archive (NBIA) database. The upper and lower limits of the 95% confidence interval of the estimated RC from the test and retest data were used to evaluate whether the longitudinal percentage changes in diffusion indices in the segmented structures in the individual patients were beyond the uncertainty and thus could be considered as true radiation-induced changes. Diffusion indices in different white matter structures showed different uncertainty ranges. The estimated RC for fractional anisotropy (FA) ranged from 5.3% to 9.6%, for mean diffusivity (MD) from 2.2% to 6.8%, for axial diffusivity (AD) from 2.4% to 5.5%, and for radial diffusivity (RD) from 2.9% to 9.7%. Overall, 23% of the patients treated by RT had FA changes, 44% had MD changes, 50% had AD changes, and 50% had RD changes beyond the uncertainty ranges. In the fornix, 85.7% and 100% of the patients showed changes beyond the uncertainty range at 6 and 18 months after RT, demonstrating that radiation has a pronounced late effect on the fornix compared to other segmented structures. It is critical to determine reliability of a change observed in an individual patient for clinical decision making. Assessments of the repeatability and

  14. Diffusion into new markets: evolving customer segments in the solar photovoltaics market

    NASA Astrophysics Data System (ADS)

    Sigrin, Ben; Pless, Jacquelyn; Drury, Easan

    2015-08-01

    The US residential solar market is growing quickly, and as solar adoption diffuses into new populations, later adopters may differ significantly from earlier ones. Using a unique household-level survey dataset including 1234 adopters and 790 non-adopters from San Diego County, California, we explore differences in attitudinal and socio-economic factors for three groups: (i) adopters and non-adopters; (ii) early and more recent adopters; (iii) consumers adopting via buying or leasing. Our results suggest that adopters overall have higher incomes, are more educated, live in larger homes, and expect to stay in their homes for longer than their non-adopting peers. They also differ in their expectations of electricity retail rate changes and the impact solar could have on their home resale value. When examining differences between early and more recent adopters, we find that recent adopters are more representative of general homeowners and more politically moderate. They are also increasingly installing solar to protect against future electricity price increases and to lower electricity costs as opposed to adopting strictly for environmental reasons. Furthermore, more recent adopters differ significantly from earlier adopters in the situations that prompted them to adopt. The findings demonstrate how solar markets are evolving, reflecting changes in the underlying drivers of consumer adoption as well as innovative solar marketing strategies.

  15. Acute Radiation Effects Resulting from Exposure to Solar Particle Event-Like Radiation

    NASA Astrophysics Data System (ADS)

    Kennedy, Ann; Cengel, Keith

    2012-07-01

    A major solar particle event (SPE) may place astronauts at significant risk for the acute radiation syndrome (ARS), which may be exacerbated when combined with other space flight stressors, such that the mission or crew health may be compromised. The National Space Biomedical Research Institute (NSBRI) Center of Acute Radiation Research (CARR) is focused on the assessment of risks of adverse biological effects related to the ARS in animal models exposed to space flight stressors combined with the types of radiation expected during an SPE. As part of this program, FDA-approved drugs that may prevent and/or mitigate ARS symptoms are being evaluated. The CARR studies are focused on the adverse biological effects resulting from exposure to the types of radiation, at the appropriate energies, doses and dose-rates, present during an SPE (and standard reference radiations, gamma rays or electrons). The ARS is a phased syndrome which often includes vomiting and fatigue. Other acute adverse biologic effects of concern are the loss of hematopoietic cells, which can result in compromised bone marrow and immune cell functions. There is also concern for skin damage from high SPE radiation doses, including burns, and resulting immune system dysfunction. Using 3 separate animal model systems (ferrets, mice and pigs), the major ARS biologic endpoints being evaluated are: 1) vomiting/retching and fatigue, 2) hematologic changes (with focus on white blood cells) and immune system changes resulting from exposure to SPE radiation with and without reduced weightbearing conditions, and 3) skin injury and related immune system functions. In all of these areas of research, statistically significant adverse health effects have been observed in animals exposed to SPE-like radiation. Countermeasures for the management of ARS symptoms are being evaluated. New research findings from the past grant year will be discussed. Acknowledgements: This research is supported by the NSBRI Center of Acute

  16. 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.

  17. Convective instability of sludge storage under evaporation and solar radiation

    NASA Astrophysics Data System (ADS)

    Tsiberkin, Kirill; Tatyana, Lyubimova

    2014-05-01

    The sludge storages are an important part of production cycle at salt manufacturing, water supply, etc. A quality of water in the storage depends on mixing of pure water and settled sediment. One of the leading factors is thermal convection. There are two main mechanisms of the layer instability exist. First, it is instability of water due to evaporation from the free surface [1]. It cools the water from upside, increases the particles concentration and leads to the instability in the near-surface layer. Second, the sediment absorbs a solar radiation and heats the liquid from below making it unstable in the near-bottom area. We assume the initial state is the mechanical equilibrium. The water and sediment particles are motionless, the sediment forms a uniform sludge layer of thickness z0, there are no evaporation and heating by solar energy, and the temperature has a linear profile is determined by fixed upper and bottom temperatures of the layer. Taking into account the evaporation and solar radiation absorption, we obtain a non-stationary solution for the temperature using Fourier series method. The local temperature gradients increases rapidly with time, and local Rayleigh number can be estimated by thermal conduction length Lt: Raloc(z,t) = gβ(δT(z,t)/δz)L4t-/νΞ , Lt ~ √Ξt, (1) where g is gravity acceleration, β, ν and Ξ are thermal volume expansion coefficient, kinematic viscosity and thermal conductivity of the liquid, respectively. Raloc* reaches the critical value at finite time t* and water motion begins. The maximal power of solar radiation in visible band equals 230 Wt/m2 at the latitude of "Uralkalii" salt manufacturer (Berezniki, Perm Region, Russian Federation). We neglect IR and UV radiation because of its huge absorption by water [2]. The evaporation speed is found using results for shallow water reservoir [3] and meteorological data for Berezniki [4]. We get the t*~ 6 · 102 s (10 min) for the layer of 1 m depth and t*~ 2 · 103 s (40

  18. Progress on an Updated National Solar Radiation Data Base for the United States: Preprint

    SciTech Connect

    Wilcox, S.; Anderberg, M.; George, R.; Marion, W.; Myers, D.; Renne, D.; Beckman, W.; DeGaetano, A.; Gueymard, C.; Perez, R.; Plantico, M.; Stackhouse, P.; Vignola, F.

    2005-09-01

    In 1992, The National Renewable Energy Laboratory (NREL) released the 1961-1990 National Solar Radiation Data Base (NSRDB), a 30-year set of hourly solar radiation data. In 2003, NREL undertook an NSRDB update project for the decade of 1991-2000.

  19. Effects of Solar UV Radiation and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    EPA Science Inventory

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions...

  20. Changes in the relationship between solar radiation and sunshine hours in large cities of China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Based on the linear relationship between solar radiation and sunshine hours, the Angstrom model is widely used to estimate solar radiation from routinely observed meteorological variables for energy harvest. However, the relationship may have been changed in the rapidly developing regions in the rec...

  1. Multifrequency radiation diffusion equations for homogeneous, refractive, lossy media and their interface conditions

    SciTech Connect

    Shestakov, Aleksei I.

    2013-06-15

    We derive time-dependent multifrequency diffusion equations for homogeneous, refractive lossy media. The equations are applicable for a domain composed of several materials with distinct refractive indexes. In such applications, the fundamental radiation variable, the intensity I, is discontinuous across material interfaces. The diffusion equations evolve a variable ξ, the integral of I over all directions divided by the square of the refractive index. Attention is focused on boundary and internal interface conditions for ξ. For numerical solutions using finite elements, it is shown that at material interfaces, the usual diffusion coefficient 1/3κ of the multifrequency equation, where κ is the opacity, is modified by a tensor diffusion term consisting of integrals of the reflectivity. Numerical results are presented. For a single material simulation, the ξ equations yield the same result as diffusion equations that evolve the spectral radiation energy density. A second simulation solves a test problem that models radiation transport in a domain comprised of materials with different refractive indexes. Results qualitatively agree with those previously published.

  2. Diffusion mechanisms in Ir-coated Re for high-temperature, radiation-cooled rocket thrusters

    NASA Technical Reports Server (NTRS)

    Hamilton, J. C.; Yang, N. Y. C.; Clift, W. M.; Boehme, D. R.; Mccarty, K. F.

    1991-01-01

    Materials used for radiation-cooled rocket thrusters must be capable of surviving under extreme conditions of high temperatures and oxidizing environments. Thruster chambers were developed using chemical-vapor-deposited (CVD) Re coated with CVD Ir on the inside surface which is exposed to hot combustion gases. Ir serves as an oxidation barrier protecting the Re which maintains structural integrity at high temperatures. In order to predict and extend the performance limits of these Ir-coated Re thrusters, the diffusion kinetics of CVD materials at temperature are studied. Thruster end ring sections were examined using electron microprobe analysis both before and after exposure to high temperature vacuum environments. The resulting elemental maps for Re, Ir, and Mo in the near-surface region allow identification of diffusion mechanisms operating at these temperatures. Line scans for Ir and Re were fit using a diffusion model to extract relevant diffusion constants. The fastest diffusion process is seen to be grain boundary diffusion with Re diffusing down grain boundaries in the Ir overlayer. The measured dependence of the diffusion rate on temperature will allow prediction of operating lifetimes for these thrusters.

  3. Solar Radiation Estimation on Building Roofs and Web-Based Solar Cadastre

    NASA Astrophysics Data System (ADS)

    Agugiaro, G.; Nex, F.; Remondino, F.; De Filippi, R.; Droghetti, S.; Furlanello, C.

    2012-07-01

    The aim of this study is the estimation of solar irradiance on building roofs in complex Alpine landscapes. Very high resolution geometric models of the building roofs are generated by means of advanced automated image matching methods. Models are combined with raster and vector data sources to estimate the incoming solar radiation hitting the roofs. The methodology takes into account for atmospheric effects, site latitude and elevation, slope and aspect of the terrain as well as the effects of shadows cast by surrounding buildings, chimneys, dormers, vegetation and terrain topography. An open source software solution has been developed and applied to a study area located in a mountainous site and containing some 1250 residential, commercial and industrial buildings. The method has been validated by data collected with a pyranometer and results made available through a prototype WebGIS platform.

  4. Evaluation of solar radiation measurement systems: EPRI/NREL final test report. Volume 1

    SciTech Connect

    Stoffel, T; Riordan, C; Bigger, J

    1992-11-01

    Measured solar radiation resource data are needed by electric utilities to evaluate the potential of renewable energy options like photovoltaics in their service territory. In this final test report, we document a cooperative project of the Electric Power Research Institute (EPRI) and the National Renewable Energy Laboratory (NREL) to compare available measurement system options for performing solar radiation resource assessments. We present the detailed results of a 6-month field comparison of thermopile-based pyranometer and pyrheliometer solar irradiance measurement systems with two different implementations of the rotating shadowband radiometer (RSR) concept installed at NREL`s Solar Radiation Research Laboratory (SRRL) in Golden, Colorado.

  5. A comparative study of methods for computing the diffuse radiation viewfactors for complex structures

    NASA Technical Reports Server (NTRS)

    Emery, A. F.; Johansson, O.; Lobo, M.; Abrous, A.

    1988-01-01

    Several different numerical methods for calculating diffuse radiation viewfactors are described. Each is applied to a range of surface configurations, from almost completely unobstructed to a dense set of intersecting surfaces. The speed, accuracy and unique characteristics are discussed in order to define optimal methods for different surface geometries.

  6. Solar Particle Acceleration Radiation and Kinetics (SPARK). A mission to understand the nature of particle acceleration

    NASA Astrophysics Data System (ADS)

    Matthews, Sarah A.; Williams, David R.; Klein, Karl-Ludwig; Kontar, Eduard P.; Smith, David M.; Lagg, Andreas; Krucker, Sam; Hurford, Gordon J.; Vilmer, Nicole; MacKinnon, Alexander L.; Zharkova, Valentina V.; Fletcher, Lyndsay; Hannah, Iain G.; Browning, Philippa K.; Innes, Davina E.; Trottet, Gerard; Foullon, Clare; Nakariakov, Valery M.; Green, Lucie M.; Lamoureux, Herve; Forsyth, Colin; Walton, David M.; Mathioudakis, Mihalis; Gandorfer, Achim; Martinez-Pillet, Valentin; Limousin, Olivier; Verwichte, Erwin; Dalla, Silvia; Mann, Gottfried; Aurass, Henri; Neukirch, Thomas

    2012-04-01

    Energetic particles are critical components of plasma populations found throughout the universe. In many cases particles are accelerated to relativistic energies and represent a substantial fraction of the total energy of the system, thus requiring extremely efficient acceleration processes. The production of accelerated particles also appears coupled to magnetic field evolution in astrophysical plasmas through the turbulent magnetic fields produced by diffusive shock acceleration. Particle acceleration is thus a key component in helping to understand the origin and evolution of magnetic structures in, e.g. galaxies. The proximity of the Sun and the range of high-resolution diagnostics available within the solar atmosphere offers unique opportunities to study the processes involved in particle acceleration through the use of a combination of remote sensing observations of the radiative signatures of accelerated particles, and of their plasma and magnetic environment. The SPARK concept targets the broad range of energy, spatial and temporal scales over which particle acceleration occurs in the solar atmosphere, in order to determine how and where energetic particles are accelerated. SPARK combines highly complementary imaging and spectroscopic observations of radiation from energetic electrons, protons and ions set in their plasma and magnetic context. The payload comprises focusing-optics X-ray imaging covering the range from 1 to 60 keV; indirect HXR imaging and spectroscopy from 5 to 200 keV, γ-ray spectroscopic imaging with high-resolution LaBr3 scintillators, and photometry and source localisation at far-infrared wavelengths. The plasma environment of the regions of acceleration and interaction will be probed using soft X-ray imaging of the corona and vector magnetography of the photosphere and chromosphere. SPARK is designed for solar research. However, in addition it will be able to provide exciting new insights into the origin of particle acceleration in

  7. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1982-01-01

    Assuming cosmic rays pervade the Galaxy, they necessarily produced high energy gamma-rays as they interact with the instellar matter and photons. The cosmic ray nucleon interactions five rise to gamma rays primarily through the decay of pi mesons, giving a unique spectrum with a maximum at approximately 68 MeV. Cosmic ray electrons produce gamma rays through bremsstrahlung, but with a markedly different energy spectral shape, one which decreases monotonically with energy. Cosmic ray electrons also interact with the interstellar starlight, optical and infrared photons, and the blackbody radiation through the Compton process. A model of galactic gamma ray production is discussed, and the predicted spatial distribution and energy spectra are presented. Considering the uncertainty in the point source contributions, the agreement between the theoretical predictions and the gamma ray data seems quite reasonable.

  8. Generation of Z mode radiation by diffuse auroral electron precipitation

    NASA Technical Reports Server (NTRS)

    Dusenbery, P. B.; Lyons, L. R.

    1985-01-01

    The generation of Z mode waves by diffuse auroral electron precipitation is investigated assuming that a loss cone exists in the upgoing portion of the distribution due to electron interactions with the atmosphere. The waves are generated at frequencies above, but very near, the local electron cyclotron frequency omega(e) and at wave normal angles larger than 90 deg. In agreement with Hewitt et al. (1983), the group velocity is directed downward in regions where the ratio of the upper hybrid frequency omega(pe) to Omega(e) is less than 0.5, so that Z mode waves excited above a satellite propagate toward it and away from the upper hybrid resonance. Z mode waves are excited in a frequency band between Omega(e) and about 1.02 Omega(e), and with maximum growth rates of about 0.001 Omega(e). The amplification length is about 100 km, which allows Z mode waves to grow to the intensities observed by high-altitude satellites.

  9. Measurements of soot production and thermal radiation from confined turbulent jet diffusion flames of methane

    SciTech Connect

    Brookes, S.J.; Moss, J.B.

    1999-01-01

    Turbulent methane/air jet diffusion flames at atmospheric and elevated pressure have been studied experimentally to provide data for coupled thermal radiation and soot production model development and validation. Although methane is only lightly sooting at atmospheric pressure, at elevated pressure the soot yield increases greatly. This allows the creation of a highly radiating flame, of moderate optical depth, within a laboratory scale rig. Spatially resolved flame properties needed for model validation have been measured at 1 and 3 atm. These measurements include detailed maps of mean mixture fraction, mean temperature, mean soot volume fraction, and mean and instantaneous spectrally resolved, path integrated radiation intensity.

  10. Local effects of partly-cloudy skies on solar and emitted radiation

    NASA Technical Reports Server (NTRS)

    Whitney, D. A.; Venable, D. D.

    1982-01-01

    A computer automated data acquisition system for atmospheric emittance, and global solar, downwelled diffuse solar, and direct solar irradiances is discussed. Hourly-integrated global solar and atmospheric emitted radiances were measured continuously from February 1981 and hourly-integrated diffuse solar and direct solar irradiances were measured continuously from October 1981. One-minute integrated data are available for each of these components from February 1982. The results of the correlation of global insolation with fractional cloud cover for the first year's data set. A February data set, composed of one-minute integrated global insolation and direct solar irradiance, cloud cover fractions, meteorological data from nearby weather stations, and GOES East satellite radiometric data, was collected to test the theoretical model of satellite radiometric data correlation and develop the cloud dependence for the local measurement site.

  11. Synergistic effect of solar radiation and solar heating to disinfect drinking water sources.

    PubMed

    Rijal, G K; Fujioka, R S

    2001-01-01

    Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol*Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60 degrees C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of < 1 CFU/100 mL within 2-5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of < 1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < F RNA virus < enterococci < E. coli < faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with solar heating of the water to disinfect the water. Thus, effective

  12. Synergistic effect of solar radiation and solar heating to disinfect drinking water sources.

    PubMed

    Rijal, G K; Fujioka, R S

    2001-01-01

    Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol*Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60 degrees C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of < 1 CFU/100 mL within 2-5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of < 1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < F RNA virus < enterococci < E. coli < faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with solar heating of the water to disinfect the water. Thus, effective

  13. Whales use distinct strategies to counteract solar ultraviolet radiation.

    PubMed

    Martinez-Levasseur, Laura M; Birch-Machin, Mark A; Bowman, Amy; Gendron, Diane; Weatherhead, Elizabeth; Knell, Robert J; Acevedo-Whitehouse, Karina

    2013-01-01

    A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies. PMID:23989080

  14. Atmospheric aerosol variability in Estonia calculated from solar radiation measurements

    NASA Astrophysics Data System (ADS)

    Russak, Viivi

    1996-10-01

    Direct solar radiation data obtained during 1955 1994 at the Tõravere Actinometric Station (Estonia) have been used to study the long-term variations of the atmospheric aerosol. In a linear approximation, the optical thickness of atmospheric aerosol averaged over months from April to August has increased by 73% at Tõravere during the last 40years. The aerosol loading of the atmosphere depends on wind direction, the southern and southeastern winds being the main carriers of aerosol. During the last decade, the increase in the optical thickness of aerosol in the case of W-, NW- and N-winds has slowed down. This is most likely caused by a reduction in the SO2 emission in Western and Central Europe as well as in Finland. In April, the advection of aerosol is greatest from the NE-direction. We suppose that this effect points to the possibility of aerosol transfer to Estonia through the Arctic regions.

  15. Whales use distinct strategies to counteract solar ultraviolet radiation.

    PubMed

    Martinez-Levasseur, Laura M; Birch-Machin, Mark A; Bowman, Amy; Gendron, Diane; Weatherhead, Elizabeth; Knell, Robert J; Acevedo-Whitehouse, Karina

    2013-01-01

    A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies.

  16. Radiation effects in heteroepitaxial InP solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Curtis, H. B.; Swartz, C. K.; Brinker, D. J.; Vargas-Aburto, C.

    1993-01-01

    Heteroepitaxial InP solar cells, with GaAs substrates, were irradiated by 0.5 and 3 MeV protons and their performance, temperature dependency, and carrier removal rates determined as a function of fluence. The radiation resistance of the present cells was significantly greater than that of non-heteroepitaxial InP cells at both proton energies. A clear difference in the temperature dependency of V(sub oc), was observed between heteroepitaxial and homoepitaxial InP cells. The analytically predicted dependence of dV(sub oc)/dT on Voc was confirmed by the fluence dependence of these quantities. Carrier removal was observed to increase with decreasing proton energy. The results obtained for performance and temperature dependency were attributed to the high dislocation densities present in the heteroepitaxial cells while the energy dependence of carrier removal was attributed to the energy dependence of proton range.

  17. Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation

    PubMed Central

    Martinez-Levasseur, Laura M.; Birch-Machin, Mark A.; Bowman, Amy; Gendron, Diane; Weatherhead, Elizabeth; Knell, Robert J.; Acevedo-Whitehouse, Karina

    2013-01-01

    A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies. PMID:23989080

  18. Stimulation of gross dimethylsulfide (DMS) production by solar radiation

    NASA Astrophysics Data System (ADS)

    Galí, Martí; Saló, Violeta; Almeda, Rodrigo; Calbet, Albert; Simó, Rafel

    2011-08-01

    Oceanic gross DMS production (GP) exerts a fundamental control on the concentration and the sea-air flux of this climatically-active trace gas. However, it is a poorly constrained process, owing to the complexity of the microbial food web processes involved and their interplay with physical forcing, particularly with solar radiation. The “inhibitor method”, using dimethyldisulfide (DMDS) or other compounds to inhibit bacterial DMS consumption, has been frequently used to determine GP in dark incubations. In the work presented here, DMDS addition was optimized for its use in light incubations. By comparing simultaneous dark and light measurements of GP in meso- to ultraoligotrophic waters, we found a significant enhancement of GP in natural sunlight in 7 out of 10 experiments. Such stimulation, which was generally between 30 and 80% on a daily basis, occurred throughout contrasting microbial communities and oceanographic settings.

  19. Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.

    1986-01-01

    Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.

  20. Laplace plane modifications arising from solar radiation pressure

    SciTech Connect

    Rosengren, Aaron J.; Scheeres, Daniel J.

    2014-05-01

    The dynamical effects of solar radiation pressure (SRP) in the solar system have been rigorously studied since the early 1900s. This non-gravitational perturbation plays a significant role in the evolution of dust particles in circumplanetary orbits, as well as in the orbital motion about asteroids and comets. For gravitationally dominated orbits, SRP is negligible and the resulting motion is largely governed by the oblateness of the primary and the attraction of the Sun. The interplay between these gravitational perturbations gives rise to three mutually perpendicular planes of equilibrium for circular satellite orbits. The classical Laplace plane lies between the equatorial and orbital planes of the primary, and is the mean reference plane about whose axis the pole of a satellite's orbit precesses. From a previously derived solution for the secular motion of an orbiter about a small body in a SRP dominated environment, we find that SRP acting alone will cause an initially circular orbit to precess around the pole of the primary's heliocentric orbital plane. When the gravitational and non-gravitational perturbations act in concert, the resulting equilibrium planes turn out to be qualitatively different, in some cases, from those obtained without considering the radiation pressure. The warping of the surfaces swept out by the modified equilibria as the semi-major axis varies depends critically on the cross-sectional area of the body exposed. These results, together with an adiabatic invariance argument on Poynting-Robertson drag, provide a natural qualitative explanation for the initial albedo dichotomy of Saturn's moon, Iapetus.