Science.gov

Sample records for absolute solar irradiance

  1. Absolute Radiometer for Reproducing the Solar Irradiance Unit

    NASA Astrophysics Data System (ADS)

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

    1989-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  6. A Helium-Cooled Absolute Cavity Radiometer For Solar And Laboratory Irradiance Measurement

    NASA Astrophysics Data System (ADS)

    Foukal, P.; Miller, P.

    1983-09-01

    We describe the design and testing of a helium-cooled absolute radiometer (HCAR) devel-oped for highly reproducible measurements of total solar irradiance and ultraviolet flux, and for laboratory standards uses. The receiver of this cryogenic radiometer is a blackened cone of pure copper whose temperature is sensed by a germanium resistance thermometer. During a duty cycle, radiant power input is compared to electrical heating in an accurate resistor wound on the receiver, as in conventional self-calibrating radiometers of the PACRAD and ACR type. But operation at helium temperatures enables us to achieve excellent radia-tive shielding between the receiver and the radiometer thermal background. This enables us to attain a sensitivity level of 10-7 watts at 30 seconds integration time, at least 10 times better than achieved by room temperature cavities. The dramatic drop of copper specific heat at helium temperatures reduces the time constant for a given mass of receiver, by a factor of 103. Together with other cryogenic materials properties such as electrical superconductivity and the high thermal conductivity of copper, this can be used to greatly reduce non-equivalence errors between electrical and radiant heating, that presently limit the absolute accuracy of radiometers to approximately 0,2%. Absolute accuracy of better than 0.01% has been achieved with a similar cryogenic radiometer in laboratory measurements of the Stefan-Boltzmann constant at NPL in the U.K. Electrical and radiometric tests con-ducted so far on our prototype indicate that comparable accuracy and long-term reproducibility can be achieved in a versatile instrument of manageable size for Shuttle flight and laboratory standards uses. This work is supported at AER under NOAA contract NA8ORAC00204 and NSF grant DMR-8260273.

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

    PubMed

    Meindl, Peter; Wähmer, Martin; Monte, Christian

    2014-10-20

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  10. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

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

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

    USGS Publications Warehouse

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

    2002-01-01

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

  12. Absolute measurement of the extreme UV solar flux

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  13. Correlations of solar cycle 22 UV irradiance

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  15. Modeled soft X-ray solar irradiances

    NASA Technical Reports Server (NTRS)

    Tobiska, W. Kent

    1994-01-01

    Solar soft X-rays have historically been inaccurately modeled in both relative variations and absolute magnitudes by empirical solar extreme ultraviolet (EUV) irradiance models. This is a result of the use of a limited number of rocket data sets which were primarily associated with the calibration of the AE-E satellite EUV data set. In this work, the EUV91 solar EUV irradiance model has been upgraded to improve the accuracy of the 3.0 to 5.0 nm relative irradiance variations. The absolute magnitude estimate of the flux in this wavelength range has also been revised upwards. The upgrade was accomplished by first digitizing the SOLRAD 11 satellite 4.4 to 6.0 nm measured energy flux data set, then extracting and extrapolating a derived 3.0 to 5.0 nm photon flux from these data, and finally by performing a correlation between these derived data and the daily and 81-day mean 10.7 cm radio flux emission using a multiple linear regression technique. A correlation coefficient of greater than 0.9 was obtained between the dependent and independent data sets. The derived and modeled 3.0 to 5.0 nm flux varies by more than an order of magnitude over a solar cycle, ranging from a flux below 1 x 10(exp 8) to a flux greater than 1 x 10(exp 9) photons per sq cm per sec. Solar rotational (27-day) variations in the flux magnitude are a factor of 2. The derived and modeled irradiance absolute values are an order of magnitude greater than previous values from rocket data sets related to the calibration of the AE-E satellite.

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

    NASA Technical Reports Server (NTRS)

    Thekaekara, M. P.

    1975-01-01

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

  17. Characterization of the DARA solar absolute radiometer

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  18. Total Irradiance Monitor Observations of Total Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Kopp, G.

    2007-12-01

    The Total Irradiance Monitor (TIM) is the most recent instrument launched to measure total solar irradiance (TSI) from space. This electrical substitution radiometer has on-orbit degradation tracking to provide very stable long- term measurements of the net solar radiation incident on the Earth, and the instrument continues the 29-year record of this natural driver of Earth climate. Currently flying on the SOlar Radiation and Climate Experiment (SORCE), the TIM has been providing stable, low-noise, and accurate measurements of TSI since early 2003. The TIM will next be flying on NASA's Glory climate mission and is one instrument of the Total Solar Irradiance Sensor (TSIS) selected to continue this important climate record well into the future. The SORCE/TIM has created renewed interest in the TSI absolute value and has acquired the first measurements of the total radiant energy released by large solar flares. Improvements in ground-based calibrations starting with the Glory/TIM will establish traceability linking current to upcoming measurements, solidifying the existing TSI climate data record in the undesirable event of a future data gap.

  19. Measurements of Absolute Abundances in Solar Flares

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.

    2014-05-01

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

  20. MEASUREMENTS OF ABSOLUTE ABUNDANCES IN SOLAR FLARES

    SciTech Connect

    Warren, Harry P.

    2014-05-01

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

  1. Absolute Abundance Measurements in Solar Flares

    NASA Astrophysics Data System (ADS)

    Warren, Harry

    2014-06-01

    We present measurements of elemental abundances in solar flares with EVE/SDO and EIS/Hinode. EVE observes both high temperature Fe emission lines Fe XV-XXIV and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (F). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is F=1.17+-0.22. Furthermore, we have compared the EVE measurements with corresponding flare observations of intermediate temperature S, Ar, Ca, and Fe emission lines taken with EIS. Our initial calculations also indicate a photospheric composition for these observations. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation in the non-flaring corona occurs.

  2. Solar Spectral Irradiance and Climate

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  3. Modeling Solar Lyman Alpha Irradiance

    NASA Technical Reports Server (NTRS)

    Pap, J.; Hudson, H. S.; Rottman, G. J.; Willson, R. C.; Donnelly, R. F.; London, J.

    1990-01-01

    Solar Lyman alpha irradiance is estimated from various solar indices using linear regression analyses. Models developed with multiple linear regression analysis, including daily values and 81-day running means of solar indices, predict reasonably well both the short- and long-term variations observed in Lyman alpha. It is shown that the full disk equivalent width of the He line at 1083 nm offers the best proxy for Lyman alpha, and that the total irradiance corrected for sunspot effect also has a high correlation with Lyman alpha.

  4. Forecasting solar extreme and far ultraviolet irradiance

    NASA Astrophysics Data System (ADS)

    Henney, C. J.; Hock, R. A.; Schooley, A. K.; Toussaint, W. A.; White, S. M.; Arge, C. N.

    2015-03-01

    A new method is presented to forecast the solar irradiance of selected wavelength ranges within the extreme ultraviolet (EUV) and far ultraviolet (FUV) bands. The technique is similar to a method recently published by Henney et al. (2012) to predict solar 10.7 cm (2.8 GHz) radio flux, abbreviated F10.7, utilizing advanced predictions of the global solar magnetic field generated by a flux transport model. In this and the previous study, we find good correlation between the absolute value of the observed photospheric magnetic field and selected EUV/FUV spectral bands. By evolving solar magnetic maps forward 1 to 7 days with a flux transport model, estimations of the Earth side solar magnetic field distribution are generated and used to forecast irradiance. For example, Pearson correlation coefficient values of 0.99, 0.99, and 0.98 are found for 1 day, 3 day, and 7 day predictions, respectively, of the EUV band from 29 to 32 nm. In the FUV, for example, the 160 to 165 nm spectral band, correlation values of 0.98, 0.97, and 0.96 are found for 1 day, 3 day, and 7 day predictions, respectively. In the previous study, the observed F10.7 signal is found to correlate well with strong magnetic field (i.e., sunspot) regions. Here we find that solar EUV and FUV signals are significantly correlated with the weaker magnetic fields associated with plage regions, suggesting that solar magnetic indices may provide an improved indicator (relative to the widely used F10.7 signal) of EUV and FUV nonflaring irradiance variability as input to ionospheric and thermospheric models.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  6. Total Solar Irradiance Variability: A Review

    NASA Technical Reports Server (NTRS)

    Pap, Judit M.

    1996-01-01

    Observations of total solar irradiance from space within the last two decaades convinced the skeptics that total irradiance varies over a wide range of periodicities: from minutes to the 11-year solar activity cycle. Analyses based on these space-borne observations have demonstrated that the irradiance variations are directly related to changes at the photosphere and the solar interior.

  7. Solar Irradiance: Observations, Proxies, and Models (Invited)

    NASA Astrophysics Data System (ADS)

    Lean, J.

    2013-12-01

    Solar irradiance has been measured from space for more than thirty years. Variations in total (spectrally integrated) solar irradiance associated with the Sun's 11-year activity cycle and 27-day rotation are now well characterized. But the magnitude, and even the sign, of spectral irradiance changes at near ultraviolet, visible and near infrared wavelengths, remain uncertain on time scales longer than a few months. Drifts in the calibration of the instruments that measure solar irradiance and incomplete understanding of the causes of irradiance variations preclude specification of multi-decadal solar irradiance variations with any confidence, including whether, or not, irradiance levels were lower during the 2008-2009 anomalously low solar activity minimum than in prior minima. The ultimate cause of solar irradiance variations is the Sun's changing activity, driven by a sub-surface dynamo that generates magnetic features called sunspots and faculae, which respectively deplete and enhance the net radiative output. Solar activity also alters parameters that have been measured from the ground for longer periods and with greater stability than the solar irradiance datasets. The longest and most stable such record is the Sun's irradiance at 10.7 cm in the radio spectrum, which is used frequently as a proxy indicator of solar irradiance variability. Models have been developed that relate the solar irradiance changes - both total and spectral - evident in extant databases to proxies chosen to best represent the sunspot darkening and facular brightening influences. The proxy models are then used to reconstruct solar irradiance variations at all wavelengths on multi-decadal time scales, for input to climate and atmospheric model simulations that seek to quantity the Sun's contribution to Earth's changing environment. This talk provides an overview of solar total and spectral irradiance observations and their relevant proxies, describes the formulation and construction of

  8. Total solar irradiance measurements with PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Schmutz, Werner; Fehlmann, André; Finsterle, Wolfgang; Kopp, Greg; Thuillier, Gerard

    2013-05-01

    PREMOS on the French satellite PICARD is the first spaceborne absolute radiometer measuring Total Solar Irradiance that has been irradiance-calibrated in vacuum with SI-traceability. The measurements of PREMOS at first light on July 27, 2010, yield a TSI value of 1360.9±0.4 W/m2 (k=1). This value agrees with the absolute TSI value measured by TIM/SORCE for this date within their combined uncertainties, and it differs by more than ten sigma from the absolute value of other space experiments, e.g. VIRGO/SOHO. The PREMOS measurements thus establish SI-traceability to a solar constant value of 1361 W/m2.

  9. Variability of solar ultraviolet irradiance

    NASA Technical Reports Server (NTRS)

    Pap, J. M.; Donnelly, R. F.; Hudson, H. S.; Rottman, G. J.; Willson, R. C.

    1991-01-01

    A model of solar Lyman alpha irradiance developed by multiple linear regression analysis, including the daily values and 81-day running means of the full disk equivalent width of the Helium line at 1083 nm, predicts reasonably well both the short- and long-term variations observed in Lyman alpha. In contrast, Lyman alpha models calculated from the 10.7-cm radio flux overestimate the observed variations in the rising portion and maximum period of solar cycle, and underestimates them during solar minimum. Models are shown of Lyman alpha based on the He-line equivalent width and 10.7-cm radio flux for those time intervals when no satellite observations exist, namely back to 1974 and after April 1989, when the measurements of the Solar Mesosphere Satellite were terminated.

  10. Updates to ISO 21348 (determining solar irradiances)

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent

    2012-07-01

    The ISO 21348 (Determining Solar Irradiances) International Standard is going through a document update. A consensus solar spectrum, solar indices/proxies descriptions, solar model descriptions, and solar measurement descriptions are among the Annexes that are proposed to the standard. These topics will be reviewed and described. The International Standards Organization (ISO) published IS 21348 in 2007 after 7 years of development by the international scientific community. In ISO, documents are reviewed on a regular basis and reaffirmed, updated, or deleted according to the votes of national delegations represented in ISO. IS 21348 provides guidelines for specifying the process of determining solar irradiances. Solar irradiances are reported through products such as measurement sets, reference spectra, empirical models, theoretical models and solar irradiance proxies or indices. These products are used in scientific and engineering applications to characterize within the natural space environment solar irradiances that are relevant to space systems and materials. Examples of applications using input solar irradiance energy include the determination of atmospheric densities for spacecraft orbit determination, attitude control and re-entry calculations, as well as for debris mitigation and collision avoidance activity. Direct and indirect pressure from solar irradiance upon spacecraft surfaces also affects attitude control separately from atmospheric density effects. Solar irradiances are used to provide inputs for a) calculations of ionospheric parameters, b) photon-induced radiation effects, and c) radiative transfer modeling of planetary atmospheres. Input solar irradiance energy is used to characterize material properties related to spacecraft thermal control, including surface temperatures, reflectivity, absorption and degradation. Solar energy applications requiring a standard process for determining solar irradiance energy include i) solar cell power

  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. Evolution Character Analysis of Total Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Xiang, N. B.

    2013-05-01

    The significant periods of total solar irradiance are 35 days and 26 days in solar cycle 23 and 24, respectively. It is inferred that the solar quasi-rotation periods are 35 days and 26 days in solar cycle 23 and 24, respectively. The value of total solar irradiance in solar cycle 24 minimum should be close to the value of Maunder minimum. On short time scales, sunspots should be the main reason to cause variations of total solar irradiance on the scale of one solar rotation cycle to several months, but not the unique one, and the variations of total solar irradiance are notrelated with the Mg II index on the scale of a few days to one solar rotation cycle.

  13. Future Satellite Observations of Solar Irradiance

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Rottman, G.; Woods, T.; Lawrence, G.; Harder, J.; McClintock, W.; Kopp, G.

    2003-01-01

    Required solar irradiance measurements for climate studies include those now being made by the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) onboard the SORCE satellite, part of the Earth Observing System fleet of NASA satellites. Equivalent or better measures of Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI, 200 to 2000 nm) are planned for the post-2010 satellites of the National Polar-orbiting Operational Environmental Satellite System ("OESS). The design life of SORCE is 5 years, so a "Solar Irradiance Gap Filler" EOS mission is being planned for launch in the 2007 time frame, to include the same TSI and SSI measurements. Besides avoiding any gap, overlap of the data sources is also necessary for determination of possible multi-decadal trends in solar irradiance. We discuss these requirements and the impacts of data gaps, and data overlaps, that may occur in the monitoring of the critical solar radiative forcing.

  14. Thematic Mapper bandpass solar exoatmospheric irradiances

    NASA Technical Reports Server (NTRS)

    Markham, B. L.; Barker, J. L.

    1987-01-01

    Based on solar irradiance data published by Neckel and Labs (1984) and Iqbal (1983), the solar exoatmospheric irradiances for Thematic Mapper (TM) bands 1, 2, 3, and 4 have been calculated. Results vary by up to 1 percent from previous published values, which were based on the earlier data of Neckel and Labs. For TM bands 5 and 7, integrated solar exoatmospheric irradiances have also been recalculated using solar irradiance data published by Labs and Neckel (1968), Arvesen et al. (1969), and Iqbal (1983). These irradiances vary by up to 6 percent from previously published results, which were based on data published by Thekaekara (1972).

  15. Absolute solar 30.4 nm flux from sounding rocket observations during the solar cycle 23 minimum

    NASA Astrophysics Data System (ADS)

    Judge, Darrell L.; McMullin, Donald R.; Ogawa, Howard S.

    A transmission grating extreme ultraviolet (EUV) spectrometer, nominally identical to the Charge, Element, and Isotope Analysis System/Solar EUV Monitor (CELIAS/SEM) instrument on the Solar and Heliospheric Observatory (SOHO), has obtained accurate measurements of the integrated absolute solar extreme ultraviolet irradiance in an 8 nm band pass centered at 30.4 nm. The spectrometer also measured the EUV/soft X-ray flux, but those data will be reported in a later paper. The instrument was launched on two sounding rocket flights from White Sands Missile Range, New Mexico, on June 26, 1996, and again on August 11, 1997, to provide a SOHO underflight calibration database in the EUV. The full disk solar 30.4+/-40nm fluxes measured by it on the above 2 days were 1.21×1010 and 1.42×1010 photons cm-2 s-1 at 1 AU, respectively. These measurements have an absolute 1σ uncertainty of 8.1%.

  16. Resolving Differences in Absolute Irradiance Measurements Between the SOHO/CELIAS/SEM and the SDO/EVE

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    The Solar EUV Monitor (SEM) onboard SOHO has measured absolute extreme ultraviolet (EUV) and soft X-ray solar irradiance nearly continuously since January 1996. The EUV Variability Experiment (EVE) on SDO, in operation since April of 2010, measures solar irradiance in a wide spectral range that encompasses the band passes (26 - 34 nm and 0.1 - 50 nm) measured by SOHO/SEM. However, throughout the mission overlap, irradiance values from these two instruments have differed by more than the combined stated uncertainties of the measurements. In an effort to identify the sources of these differences and eliminate them, we investigate in this work the effect of reprocessing the SEM data using a more accurate SEM response function (obtained from synchrotron measurements with a SEM sounding-rocket clone instrument taken after SOHO was already in orbit) and time-dependent, measured solar spectral distributions - i.e., solar reference spectra that were unavailable prior to the launch of the SDO. We find that recalculating the SEM data with these improved parameters reduces mean differences with the EVE measurements from about 20 % to less than 5 % in the 26 - 34 nm band, and from about 35 % to about 15 % for irradiances in the 0.1 - 7 nm band extracted from the SEM 0.1 - 50 nm channel.

  17. Absolute Cavity Pyrgeometer to Measure the Absolute Outdoor Longwave Irradiance with Traceability to International System of Units, SI

    SciTech Connect

    Reda, I.; Zeng, J.; Scheuch, J.; Hanssen, L.; Wilthan, B.; Myers, D.; Stoffel, T.

    2012-03-01

    This article describes a method of measuring the absolute outdoor longwave irradiance using an absolute cavity pyrgeometer (ACP), U.S. Patent application no. 13/049, 275. The ACP consists of domeless thermopile pyrgeometer, gold-plated concentrator, temperature controller, and data acquisition. The dome was removed from the pyrgeometer to remove errors associated with dome transmittance and the dome correction factor. To avoid thermal convection and wind effect errors resulting from using a domeless thermopile, the gold-plated concentrator was placed above the thermopile. The concentrator is a dual compound parabolic concentrator (CPC) with 180{sup o} view angle to measure the outdoor incoming longwave irradiance from the atmosphere. The incoming irradiance is reflected from the specular gold surface of the CPC and concentrated on the 11 mm diameter of the pyrgeometer's blackened thermopile. The CPC's interior surface design and the resulting cavitation result in a throughput value that was characterized by the National Institute of Standards and Technology. The ACP was installed horizontally outdoor on an aluminum plate connected to the temperature controller to control the pyrgeometer's case temperature. The responsivity of the pyrgeometer's thermopile detector was determined by lowering the case temperature and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The responsivity is then used to calculate the absolute atmospheric longwave irradiance with an uncertainty estimate (U{sub 95}) of {+-}3.96 W m{sup 02} with traceability to the International System of Units, SI. The measured irradiance was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the Interim World Infrared Standard Group, WISG. A total of 408 readings were collected over three different nights. The calculated irradiance measured by the ACP was 1.5 W/m{sup 2} lower than that

  18. An absolute cavity pyrgeometer to measure the absolute outdoor longwave irradiance with traceability to international system of units, SI

    NASA Astrophysics Data System (ADS)

    Reda, Ibrahim; Zeng, Jinan; Scheuch, Jonathan; Hanssen, Leonard; Wilthan, Boris; Myers, Daryl; Stoffel, Tom

    2012-03-01

    This article describes a method of measuring the absolute outdoor longwave irradiance using an absolute cavity pyrgeometer (ACP), U.S. Patent application no. 13/049, 275. The ACP consists of domeless thermopile pyrgeometer, gold-plated concentrator, temperature controller, and data acquisition. The dome was removed from the pyrgeometer to remove errors associated with dome transmittance and the dome correction factor. To avoid thermal convection and wind effect errors resulting from using a domeless thermopile, the gold-plated concentrator was placed above the thermopile. The concentrator is a dual compound parabolic concentrator (CPC) with 180° view angle to measure the outdoor incoming longwave irradiance from the atmosphere. The incoming irradiance is reflected from the specular gold surface of the CPC and concentrated on the 11 mm diameter of the pyrgeometer's blackened thermopile. The CPC's interior surface design and the resulting cavitation result in a throughput value that was characterized by the National Institute of Standards and Technology. The ACP was installed horizontally outdoor on an aluminum plate connected to the temperature controller to control the pyrgeometer's case temperature. The responsivity of the pyrgeometer's thermopile detector was determined by lowering the case temperature and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The responsivity is then used to calculate the absolute atmospheric longwave irradiance with an uncertainty estimate (U95) of ±3.96 W m-2 with traceability to the International System of Units, SI. The measured irradiance was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the Interim World Infrared Standard Group, WISG. A total of 408 readings were collected over three different nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two

  19. Studying Solar Irradiance Variability with Wavelet Technique

    NASA Technical Reports Server (NTRS)

    Vigouroux, Anne; Pap, Judit

    1995-01-01

    The detection of variations in solar irradiance by satellite-based experiments during the last 17 years stimulated modelling efforts to help to identify their causes and to provide estimates for irradiance data when no satellite observations exist.

  20. Long-Term Solar Irradiance Variability

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1996-01-01

    Measurements of the solar energy throughout the solar spectrum and understanding its variability provide important information about the physical processes and structural changes in the solar interior and in the solar atmosphere...The aim of this paper is to discuss the solar-cycle-related long-term changes in solar total and UV irradiances. The spaceborne irradiance observations are compared to ground-based indices of solar magnetic activity, such as the Photometric Sunspot Index, full disk magnetic flux, and the Mt. Wilson Magnetic Plage Strength Index.

  1. Solar extreme ultraviolet irradiance: Present, past, and future

    NASA Astrophysics Data System (ADS)

    Lean, J. L.; Woods, T. N.; Eparvier, F. G.; Meier, R. R.; Strickland, D. J.; Correira, J. T.; Evans, J. S.

    2011-01-01

    New models of solar extreme ultraviolet (EUV) irradiance variability are constructed in 1 nm bins from 0 to 120 nm using multiple regression of the Mg II and F10.7 solar activity indices with irradiance observations made during the descending phase of cycle 23. The models have been used to reconstruct EUV spectra daily since 1950, annually since 1610, to forecast daily EUV irradiance and to estimate future levels in cycle 24. A two-component model developed by scaling the observed rotational modulation of the two solar indices underestimates the solar cycle changes that the Solar EUV Experiment (SEE) reports at wavelengths shorter than 40 nm and longer than 80 nm. A three-component model implemented by including an additional term derived from the smoothed Mg II index better reproduces the measurements at all wavelengths. The three-component model is consistent with variations in the EUV energy from 0 to 45 nm that produces the far ultraviolet (FUV) terrestrial dayglow observed by the Global Ultraviolet Imager (GUVI). However, the spectral structure of this third component is complex, and its origin is uncertain. Analogous two- and three-component models are also developed with absolute scales determined by the NRLEUV2 spectrum of the quiet Sun rather than by the SEE average spectrum. Assessment of the EUV absolute spectrum and variability of the four different models indicate that during solar cycle 23, the EUV irradiance (0 to 120 nm) increased 100 ± 30%, from 2.9 ± 0.2 to 5.8 ± 0.9 mWm-2, and may have been as low as 1.9 ± 0.5 mWm-2 during the 17th-century Maunder Minimum. Near the peak of upcoming solar cycle 24, EUV irradiance is expected to increase 40% to 80% above the 2008 minimum values.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Comparison of Solar UV Spectral Irradiance from SUSIM and SORCE

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Knowledge of solar spectral irradiance (SSI) is important in determining the impact of solar variability on climate. Observations of UV SSI have been made by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) on the Upper Atmosphere Research Satellite (UARS), the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE), and the Solar Irradiance Monitor (SIM), both on the Solar Radiation and Climate Experiment (SORCE) satellite. Measurements by SUSIM and SORCE overlapped from 2003 to 2005. SUSIM and SORCE observations represent ˜ 20 years of absolute UV SSI. Unfortunately, significant differences exist between these two data sets. In particular, changes in SORCE UV SSI measurements, gathered at moderate and minimum solar activity, are a factor of two greater than the changes in SUSIM observations over the entire solar cycle. In addition, SORCE UV SSI have a substantially different relationship with the Mg ii index than did earlier UV SSI observations. Acceptance of these new SORCE results impose significant changes on our understanding of UV SSI variation. Alternatively, these differences in UV SSI observations indicate that some or all of these instruments have changes in instrument responsivity that are not fully accounted for by the current calibration. In this study, we compare UV SSI changes from SUSIM with those from SIM and SOLSTICE. The primary results are that (1) long-term observations by SUSIM and SORCE generally do not agree during the overlap period (2003 - 2005), (2) SUSIM observations during this overlap period are consistent with an SSI model based on Mg ii and early SUSIM SSI, and (3) when comparing the spectral irradiance for times of similar solar activity on either side of solar minimum, SUSIM observations show slight differences while the SORCE observations show variations that increase with time between spectra. Based on this work, we conclude that the instrument responsivity for SOLSTICE and SIM need to be reevaluated before these

  4. Solar spectral irradiance and total solar irradiance at a solar minimum

    NASA Astrophysics Data System (ADS)

    Benevolenskaya, E. E.; Shapovalov, S. N.; Kostuchenko, I. G.

    2014-12-01

    Results are presented for a wavelet analysis of solar spectral irradiance (SSI) in the ultraviolet to infrared range and total solar irradiance (TSI). The study is based on data collected by the Solar Radiation and Climate Experiment ( SORCE) satellite from March 10, 2007 to January 23, 2010. Cross-wavelet analysis finds relationships of varying degrees of tightness between SSI, TSI, and magnetic flux in a sunspot zone on the surface rotation timescales of solar activity complexes. Wavelet coherence shows how magnetic flux variations within a latitudinal sunspot zone are related with spectral irradiance variations. For example, variations in ultraviolet radiation at UV 200.5 nm are in phase with those of the magnetic flux associated with solar activity complexes. However, there is an unusual interval UV 310 to 380 nm, in which coherent structures disappear and UV radiation variations do not follow the changes in the magnetic flux.

  5. Solar irradiance short wave radiation users guide

    NASA Astrophysics Data System (ADS)

    Martinolich, Paul; Arnone, Robert A.

    1995-05-01

    Solar irradiance for short wave radiation (400-700 nm) at the sea surface can be calculated using inputs obtained from satellite systems and model estimates. The short wave solar irradiance is important for estimating the surface heating that occurs in the near surface and estimating the available irradiance for biological growth in the upper ocean. The variability of the solar irradiance is believed to have significant influence on the global carbon cycle. This users guide provides an understanding of the models and operational procedures for using the software and understanding the results.

  6. The Contribution of the Solcon Instrument to the Long Term Total Solar Irradiance Observation

    NASA Technical Reports Server (NTRS)

    Dewitte, S.; Joukoff, A.; Crommelynck, D.; Lee, R. B., III; Helizon, R.

    1999-01-01

    On century time scales, the variation in the total solar irradiance received by the earth is believed to be a major climate change driver. Therefore accurate and time stable measurements of the total solar irradiance are necessary. We present the latest contribution of the SOLar CONstant (SOLCON) instrument to these measurements, namely its measurements during the International Extreme Ultraviolet Hitchhiker (IEH) 3 space shuttle flight, and its results: the verification of the ageing of the Earth Radiation Budget Satellite (ERBS), and the measurement of the Space Absolute Radiometric Reference (SARR) adjustment coefficients for the Variability of solar IRradiance and Gravity Oscillations (VIRGO) radiometers.

  7. Simultaneous measurement of the total solar irradiance and solar diameter by the PICARD mission

    NASA Astrophysics Data System (ADS)

    Thuillier, Gérard; Dewitte, Steven; Schmutz, Werner; Picard Team

    2006-01-01

    A mission dedicated to simultaneous measurements of the solar diameter, spectral, and total solar irradiance is presently in development for launch end of the year 2008 on board of a microsatellite under the responsibility of Centre National d'Etudes Spatiales. The payload will consist of an imaging telescope, three filter radiometers with in total twelve channels, and two independent absolute radiometers. The scientific aims are presented as well as the concepts and properties of the instrumentation. This mission is named PICARD after the pioneering work of Jean Picard (1620-1682) who precisely determined the solar diameter during the Maunder minimum.

  8. Total solar irradiance record accuracy and recent improvements

    NASA Astrophysics Data System (ADS)

    Kopp, Greg

    The total solar irradiance (TSI) data record includes uninterrupted measurements from over 10 spaceborne instruments spanning the last 31 years. Continuity of on-orbit measurements allows adjustments for instrument offsets to create a TSI composite needed for estimating solar influences on Earth's climate. Because climate sensitivities to solar forcings are determined not only from direct TSI measurements over recent 11-year solar cycles but also from reconstructions of historical solar variability based on the recent measurements, the accuracy of the TSI record is critical. This climate data record currently relies on both instrument stability and measurement continuity, although improvements in absolute accuracy via better instrument calibrations and new test facilities promise to reduce this current reliance on continuity. The Total Irradiance Monitor (TIM) is striving for improved levels of absolute accuracy, and a new TSI calibration facility is now able to validate the accuracy of modern instruments and diagnose causes of offsets between different TSI instruments. The instrument offsets are due to calibration errors. As of early 2010, none of the on-orbit instruments have been calibrated end-to-end to the needed accuracy levels. The new TSI Radiometer Facility (TRF) built for NASA's Glory mission provides these new calibration capabilities. Via direct optical power comparisons to a NIST-calibrated cryogenic radiometer, this ground-based facility provides calibrations of a TSI instrument much as the instrument is operated in space: under vacuum, at full solar irradiance power levels, and with uniform incoming light for irradiance measurements. Both the PICARD/PREMOS and the upcoming Glory/TIM instruments have been tested in this new facility, helping improve the absolute accuracy of the TSI data record and diagnose the causes of existing instrument offsets. In addition to being benchmarked to this new ground-based reference, the Glory/TIM and the future TSIS

  9. Solar irradiance measurements - Minimum through maximum solar activity

    NASA Technical Reports Server (NTRS)

    Lee, R. B., III; Gibson, M. A.; Shivakumar, N.; Wilson, R.; Kyle, H. L.; Mecherikunnel, A. T.

    1991-01-01

    The Earth Radiation Budget Satellite (ERBS) and the NOAA-9 spacecraft solar monitors were used to measure the total solar irradiance during the period October 1984 to December 1989. Decreasing trends in the irradiance measurements were observed as sunspot activity decreased to minimum levels in 1986; after 1986, increasing trends were observed as sunspot activity increased. The magnitude of the irradiance variability was found to be approximately 0.1 percent between sunspot minimum and maximum (late 1989). When compared with the 1984 to 1989 indices of solar magnetic activity, the irradiance trends appear to be in phase with the 11-year sunspot cycle. Both irradiance series yielded 1,365/sq Wm as the mean value of the solar irradiance, normalized to the mean earth/sun distance. The monitors are electrical substitution, active-cavity radiometers with estimated measurement precisions and accuracies of less than 0.02 and 0.2 percent, respectively.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  11. Introducing an Absolute Cavity Pyrgeometer for Improving the Atmospheric Longwave Irradiance Measurement (Presentation)

    SciTech Connect

    Reda, I.; Hansen, L.; Zeng, J.

    2012-08-01

    Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technology (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG. A total of 408 readings was collected over three different clear nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two pyrgeometers that are traceable to WISG. Further development and characterization of the ACP might contribute to the effort of improving the uncertainty and traceability of WISG to SI.

  12. TSIS: The Total Solar Irradiance Sensor

    NASA Astrophysics Data System (ADS)

    Sparn, T.; Pilewskie, P.; Harder, J.; Kopp, G.; Richard, E.; Fontenla, J.; Woods, T.

    2008-12-01

    The Total Solar Irradiance Sensor (TSIS) is a dual-instrument package that will acquire solar irradiance in the next decade on the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Originally de-manifested during the 2006 NPOESS restructuring, TSIS was restored following a decision by the NPOESS Executive Committee earlier this year because of its critical role in determining the natural forcings of the climate system and the high priority given it by the 2007 Earth Science Decadal Survey. TSIS is comprised of the Total Irradiance Monitor, or TIM, which measures the total solar irradiance (TSI) that is incident at the boundaries of the atmosphere; and the Spectral Irradiance Monitor, or SIM, which measures solar spectral irradiance (SSI) from 200 nm to 2400 nm (96 percent of the TSI). The TSIS TIM and SIM are heritage instruments to those currently flying on the NASA Solar Irradiance and Climate Experiment (SORCE). Both were selected as part of the TSIS because of their unprecedented measurement accuracy and stability, and because both measurements are essential to constraining the energy input to the climate system and interpreting the response of climate to external forcing. This paper will describe those attributes of TSIS which uniquely define its capability to continue the 30-year record of TSI and to extend the new 5-year record of SSI. The role of the solar irradiance data record in the present climate state, as well as in past and future climate change, will also be presented.

  13. Measuring Broadband IR Irradiance in the Direct Solar Beam (Presentation)

    SciTech Connect

    Reda, I.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 um and 50 um, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 um to 3 um, while the present photovoltaic cells are limited to approximately 0.3 um to 1 um. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and are calibrated with traceability to consensus reference, yet are calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 um to 50 um, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degrees to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  14. Measuring Broadband IR Irradiance in the Direct Solar Beam (Poster)

    SciTech Connect

    Reda, I.; Konings, J.; Xie, Y.; Dooraghi, M.; Sengupta, M.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 micrometers and 50 micrometers, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 micrometers to 3 micrcometers, while the present photovoltaic cells are limited to approximately 0.3 micrometers to 1 micrometers. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus reference, yet calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 micrometers to 50 micrometers, as first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degres to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  15. Reconstruction of solar UV irradiance since 1974

    NASA Astrophysics Data System (ADS)

    Krivova, N. A.; Solanki, S. K.; Wenzler, T.; Podlipnik, B.

    2009-09-01

    Variations of the solar UV irradiance are an important driver of chemical and physical processes in the Earth's upper atmosphere and may also influence global climate. Here we reconstruct solar UV irradiance in the range 115-400 nm over the period 1974-2007 by making use of the recently developed empirical extension of the Spectral And Total Irradiance Reconstruction (SATIRE) models employing Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) data. The evolution of the solar photospheric magnetic flux, which is a central input to the model, is described by the magnetograms and continuum images recorded at the Kitt Peak National Solar Observatory between 1974 and 2003 and by the Michelson Doppler Imager instrument on SOHO since 1996. The reconstruction extends the available observational record by 1.5 solar cycles. The reconstructed Ly-α irradiance agrees well with the composite time series by Woods et al. (2000). The amplitude of the irradiance variations grows with decreasing wavelength and in the wavelength regions of special interest for studies of the Earth's climate (Ly-α and oxygen absorption continuum and bands between 130 and 350 nm) is 1-2 orders of magnitude stronger than in the visible or if integrated over all wavelengths (total solar irradiance).

  16. The Next Spaceflight Solar Irradiance Sensor: TSIS

    NASA Astrophysics Data System (ADS)

    Kopp, Greg; Pilewskie, Peter; Richard, Erik

    2016-05-01

    The Total and Spectral Solar Irradiance Sensor (TSIS) will continue measurements of the solar irradiance with improved accuracies and stabilities over extant spaceflight instruments. The two TSIS solar-observing instruments include the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) for measuring total- and spectral- solar-irradiance, respectively. The former provides the net energy powering the Earth’s climate system while the latter helps attribute where that energy is absorbed by the Earth’s atmosphere and surface. Both spaceflight instruments are assembled and being prepared for integration on the International Space Station. With operations commencing in late 2017, the TSIS is intended to overlap with NASA’s ongoing SOlar Radiation and Climate Experiment (SORCE) mission, which launched in 2003 and contains the first versions of both the TIM and SIM instruments, as well as with the TSI Calibration Transfer Experiment (TCTE), which began total solar irradiance measurements in 2013. We summarize the TSIS’s instrument improvements and intended solar-irradiance measurements.

  17. Error budget for a calibration demonstration system for the reflected solar instrument for the climate absolute radiance and refractivity observatory

    NASA Astrophysics Data System (ADS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2013-09-01

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

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

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2013-01-01

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

  19. Introducing an Absolute Cavity Pyrgeometer (ACP) for Improving the Atmospheric Longwave Irradiance Measurement (Poster)

    SciTech Connect

    Reda, I.; Stoffel, T.

    2012-03-01

    Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technology (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG.

  20. Variability of Solar Irradiances Using Wavelet Analysis

    NASA Technical Reports Server (NTRS)

    Pesnell, William D.

    2007-01-01

    We have used wavelets to analyze the sunspot number, F10.7 (the solar irradiance at a wavelength of approx.10.7 cm), and Ap (a geomagnetic activity index). Three different wavelets are compared, showing how each selects either temporal or scale resolution. Our goal is an envelope of solar activity that better bounds the large amplitude fluctuations form solar minimum to maximum. We show how the 11-year cycle does not disappear at solar minimum, that minimum is only the other part of the solar cycle. Power in the fluctuations of solar-activity-related indices may peak during solar maximum but the solar cycle itself is always present. The Ap index has a peak after solar maximum that appears to be better correlated with the current solar cycle than with the following cycle.

  1. Preliminary error budget for the reflected solar instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Astrophysics Data System (ADS)

    Thome, K.; Gubbels, T.; Barnes, R.

    2011-10-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as the most critical method to determine the accuracy of climate change. The CLARREO Project will implement a spaceborne earth observation mission designed to provide rigorous SI-traceable observations (i.e., radiance, reflectance, and refractivity) that are sensitive to a wide range of key decadal change variables. The instrument suite includes emitted infrared spectrometers, global navigation receivers for radio occultation, and reflected solar spectrometers. The measurements will be acquired for a period of five years and will enable follow-on missions to extend the climate record over the decades needed to understand climate change. This work describes a preliminary error budget for the RS sensor. The RS sensor will retrieve at-sensor reflectance over the spectral range from 320 to 2300 nm with 500-m GIFOV and a 100-km swath width. The current design is based on an Offner spectrometer with two separate focal planes each with its own entrance aperture and grating covering spectral ranges of 320-640, 600-2300 nm. Reflectance is obtained from the ratio of measurements of radiance while viewing the earth's surface to measurements of irradiance while viewing the sun. The requirement for the RS instrument is that the reflectance must be traceable to SI standards at an absolute uncertainty <0.3%. The calibration approach to achieve the ambitious 0.3% absolute calibration uncertainty is predicated on a reliance on heritage hardware, reduction of sensor complexity, and adherence to detector-based calibration standards. The design above has been used to develop a preliminary error budget that meets the 0.3% absolute requirement. Key components in the error budget are geometry differences between the solar and earth views, knowledge of attenuator behavior when viewing the sun, and

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

    PubMed

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

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Gubbels, Timothy; Barnes, Robert

    2011-01-01

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

  4. Rotational Variability in Ultraviolet Solar Spectral Irradiance

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  5. Total solar irradiance reconstruction using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Tebabal Yirdaw, Ambelu; Damtie, Baylie; Nigussie, Melessew; Bires, Abiyot; Yizengaw, Endawoke

    2015-08-01

    A feed-forward neural network which can account for nonlinear relationships was used to reconstruct total solar irradiance (TSI). A single layer feed forward neural network with back-propagation algorithm have been implemented for reconstructing daily total solar irradiance from daily photometric sunspot index, and core to wing ratio of Mg II index data. The data year from 1978 to 2013 was used for the training, validation and testing purpose. In order to obtain the optimum neural network for TSI reconstruction, the root mean square error (RMSE), mean absolute error (MAE) and regression coefficient have been taken into account. We have carried out the analysis is made by comparing the reconstructed TSI from neural networks (NNs ) and TSI measurement from satellite. We have found out that the reconstructed TSI and the PMOD composite have the correlation coefficient of about R=0.9307 over the span of the recorded, 1978 to 2013. The NNs model output indicates that reconstructed TSI from solar proxies (photometric index and MgII ) can explain 86.6% of the variance of TSI. Neural network is able to recreate TSI observations on a time scale of a day. This reconstructed TSI using NNs further strengthens the view that surface magnetism indeed plays a dominant role in modulating solar irradiance.

  6. Solar EUV irradiance for space weather applications

    NASA Astrophysics Data System (ADS)

    Viereck, R. A.

    2015-12-01

    Solar EUV irradiance is an important driver of space weather models. Large changes in EUV and x-ray irradiances create large variability in the ionosphere and thermosphere. Proxies such as the F10.7 cm radio flux, have provided reasonable estimates of the EUV flux but as the space weather models become more accurate and the demands of the customers become more stringent, proxies are no longer adequate. Furthermore, proxies are often provided only on a daily basis and shorter time scales are becoming important. Also, there is a growing need for multi-day forecasts of solar EUV irradiance to drive space weather forecast models. In this presentation we will describe the needs and requirements for solar EUV irradiance information from the space weather modeler's perspective. We will then translate these requirements into solar observational requirements such as spectral resolution and irradiance accuracy. We will also describe the activities at NOAA to provide long-term solar EUV irradiance observations and derived products that are needed for real-time space weather modeling.

  7. Effect of aerosols on solar UV irradiances during the Photochemical Activity and Solar Ultraviolet Radiation Campaign

    NASA Astrophysics Data System (ADS)

    Kylling, A.; Bais, A. F.; Blumthaler, M.; Schreder, J.; Zerefos, C. S.; Kosmidis, E.

    1998-10-01

    Surface UV irradiances were measured at two different sites in Greece during June 1996 under noncloudy conditions. The measured UV irradiances are simulated by a radiative transfer model using measured ozone density and aerosol optical depth profiles. The absolute difference between model and measurements ranges between -5% and +5% with little dependence on wavelength. The temporal and solar zenith angle dependence in the difference between model and measurement suggests that part of this difference may be explained by assumptions made about the aerosol single-scattering albedo and phase function. Simulated spectra including aerosols are compared with calculated spectra excluding aerosols. It is found that for otherwise similar atmospheric conditions the UVB irradiance is reduced with respect to aerosol free conditions by 5% to 35% depending on the aerosol optical depth and single-scattering albedo. For the campaign period, changes in the aerosol loading gave larger variations in the surface UV irradiances than the changes seen in the ozone column.

  8. A new absolute reference for atmospheric longwave irradiance measurements with traceability to SI units

    NASA Astrophysics Data System (ADS)

    Gröbner, J.; Reda, I.; Wacker, S.; Nyeki, S.; Behrens, K.; Gorman, J.

    2014-06-01

    Two independently designed and calibrated absolute radiometers measuring downwelling longwave irradiance were compared during two field campaigns in February and October 2013 at Physikalisch Meteorologisches Observatorium Davos/World Radiation Center (PMOD/WRC). One absolute cavity pyrgeometer (ACP) developed by NREL and up to four Integrating Sphere Infrared Radiometers (IRIS) developed by PMOD/WRC took part in these intercomparisons. The internal consistency of the IRIS radiometers and the agreement with the ACP were within ±1 W m-2, providing traceability of atmospheric longwave irradiance to the international system of units with unprecedented accuracy. Measurements performed during the two field campaigns and over the past 4 years have shown that the World Infrared Standard Group (WISG) of pyrgeometers is underestimating clear-sky atmospheric longwave irradiance by 2 to 6 W m-2, depending on the amount of integrated water vapor (IWV). This behavior is an instrument-dependent feature and requires an individual sensitivity calibration of each pyrgeometer with respect to an absolute reference such as IRIS or ACP. For IWV larger than 10 mm, an average sensitivity correction of +6.5% should be applied to the WISG in order to be consistent with the longwave reference represented by the ACP and IRIS radiometers. A concerted effort at international level will need to be implemented in order to correct measurements of atmospheric downwelling longwave irradiance traceable to the WISG.

  9. Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

    NASA Technical Reports Server (NTRS)

    Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.

    2012-01-01

    Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

  10. Sounding rocket measurement of the absolute solar EUV flux utilizing a silicon photodiode

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.

  11. Solar EUV irradiance variability derived from terrestrial far ultraviolet dayglow observations

    NASA Astrophysics Data System (ADS)

    Strickland, D. J.; Lean, J. L.; Meier, R. R.; Christensen, A. B.; Paxton, L. J.; Morrison, D.; Craven, J. D.; Walterscheid, R. L.; Judge, D. L.; McMullin, D. R.

    2004-02-01

    Remotely sensed ultraviolet emissions from the Earth's upper atmosphere are shown to mirror fluctuations in solar EUV irradiance during July 2002, including the overall increase and decrease as the Sun rotated, and episodic increases associated with multiple solar flares. The TIMED/GUVI dayglow observations are used to derive a new quantity, QEUVGUVI, which is a measure of integrated solar EUV electromagnetic energy shortward of 45 nm. Both the absolute QEUVGUVI values and their modulation by solar rotation agree well with the corresponding solar EUV energy estimated by the NRLEUV irradiance variability model. The QEUVGUVI values do not support recent suggestions that the solar EUV irradiances estimated by the model of Hinteregger et al. be increased by a factor of four, nor even a factor of two.

  12. The IAG solar flux atlas: Accurate wavelengths and absolute convective blueshift in standard solar spectra

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Mrotzek, N.; Lemke, U.; Hinrichs, J.; Reinsch, K.

    2016-03-01

    We present a new solar flux atlas with the aim of understanding wavelength precision and accuracy in solar benchmark data. The atlas covers the wavelength range 405-2300 nm and was observed at the Institut für Astrophysik, Göttingen (IAG), with a Fourier transform spectrograph (FTS). In contrast to other FTS atlases, the entire visible wavelength range was observed simultaneously using only one spectrograph setting. We compare the wavelength solution of the new atlas to the Kitt Peak solar flux atlases and to the HARPS frequency-comb calibrated solar atlas. Comparison reveals systematics in the two Kitt Peak FTS atlases resulting from their wavelength scale construction, and shows consistency between the IAG and the HARPS atlas. We conclude that the IAG atlas is precise and accurate on the order of ± 10 m s-1 in the wavelength range 405-1065 nm, while the Kitt Peak atlases show deviations as large as several ten to 100 m s-1. We determine absolute convective blueshift across the spectrum from the IAG atlas and report slight differences relative to results from the Kitt Peak atlas that we attribute to the differences between wavelength scales. We conclude that benchmark solar data with accurate wavelength solution are crucial to better understand the effect of convection on stellar radial velocity measurements, which is one of the main limitations of Doppler spectroscopy at m s -1 precision. Data (FITS files of the spectra) and Table A.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A65

  13. Solar Irradiance Observations during Solar Cycles 22 and 23

    NASA Astrophysics Data System (ADS)

    White, O. R.; de Toma, G.; Chapman, G. A.; Walton, S. R.; Preminger, D. G.; Cookson, A. M.; Harvey, K. L.; Livingston, W. C.

    2002-05-01

    We present a study of Total Solar Irradiance (TSI) variations during solar cycles 22 and 23 from 1986 to the present. We will review the recent measurements of solar magnetism, solar activity, and radiative variability from both ground-based and space observatories and compare TSI observations with empirical models of solar irradiance variability based on facular and sunspot observations. To estimate facular/plage and sunspot contribution to TSI we use the photometric indices derived from the SFO full-disk solar images from 1988 to the present in the CaIIK line at 393.4nm and in the red continuum at 672.3 nm. In these indices, each solar structure is included with its measured contrast and area. We also use the MgII core-to-wing index from space observatories as an alternative index for plages and network. Comparison of the rising and maximum phases of the two solar cycles, shows that cycle 23 is magnetically weaker with sunspot and facular area almost a factor of two lower than in solar cycle 22. However, analysis of multi-wavelength observations indicate that different wavelengths respond differently to the decreased magnetic activity during solar cycle 23.

  14. The solar irradiance: observations and modelling

    NASA Astrophysics Data System (ADS)

    Cessateur, Gaël; Schmutz, Werner; Shapiro, Alexander

    2015-04-01

    The knowledge of the solar spectral irradiance (SSI) and its variability is an essential parameter for space weather and space climate studies. Many observations of the SSI have been performed in a recent past, but the level of confidence is rather low when considering long time scales, since space instruments are often suffering from degradation problems. Many SSI models have been also developed, and some of them are excellent inputs for many space climate models. We will then review the different data sets available of the SSI for the short term time-scales as well as for the long term, including both observations and models. We will also emphasize about our new irradiance model, COSIR for Code of Solar Irradiance Reconstruction, which is successful at reproducing the solar rotational modulation as seen in the PREMOS, Virgo and SORCE data.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  16. Comparison of absolute spectral irradiance responsivity measurement techniques using wavelength-tunable lasers

    SciTech Connect

    Ahtee, Ville; Brown, Steven W.; Larason, Thomas C.; Lykke, Keith R.; Ikonen, Erkki; Noorma, Mart

    2007-07-10

    Independent methods for measuring the absolute spectral irradiance responsivity of detectors have been compared between the calibration facilities at two national metrology institutes, the Helsinki University of Technology (TKK), Finland, and the National Institute of Standards and Technology (NIST). The emphasis is on the comparison of two different techniques for generating a uniform irradiance at a reference plane using wavelength-tunable lasers. At TKK's Laser Scanning Facility (LSF) the irradiance is generated by raster scanning a single collimated laser beam, while at the NIST facility for Spectral Irradiance and Radiance Responsivity Calibrations with Uniform Sources (SIRCUS), lasers are introduced into integrating spheres to generate a uniform irradiance at a reference plane. The laser-based irradiance responsivity results are compared to a traditional lamp-monochromator-based irradiance responsivity calibration obtained at the NIST Spectral Comparator Facility (SCF). A narrowband filter radiometer with a24 nm bandwidth and an effective band-center wavelength of 801 nm was used as the artifact. The results of the comparison between the different facilities, reported for the first time in the near-infrared wavelength range, demonstrate agreement at the uncertainty level of less than 0.1%. This result has significant implications in radiation thermometry and in photometry as well as in radiometry.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  18. Ionospheric Change and Solar EUV Irradiance

    NASA Astrophysics Data System (ADS)

    Sojka, J. J.; David, M.; Jensen, J. B.; Schunk, R. W.

    2011-12-01

    The ionosphere has been quantitatively monitored for the past six solar cycles. The past few years of observations are showing trends that differ from the prior cycles! Our good statistical relationships between the solar radio flux index at 10.7 cm, the solar EUV Irradiance, and the ionospheric F-layer peak density are showing indications of divergence! Present day discussion of the Sun-Earth entering a Dalton Minimum would suggest change is occurring in the Sun, as the driver, followed by the Earth, as the receptor. The dayside ionosphere is driven by the solar EUV Irradiance. But different components of this spectrum affect the ionospheric layers differently. For a first time the continuous high cadence EUV spectra from the SDO EVE instrument enable ionospheric scientists the opportunity to evaluate solar EUV variability as a driver of ionospheric variability. A definitive understanding of which spectral components are responsible for the E- and F-layers of the ionosphere will enable assessments of how over 50 years of ionospheric observations, the solar EUV Irradiance has changed. If indeed the evidence suggesting the Sun-Earth system is entering a Dalton Minimum periods is correct, then the comprehensive EVE solar EUV Irradiance data base combined with the ongoing ionospheric data bases will provide a most fortuitous fiduciary reference baseline for Sun-Earth dependencies. Using the EVE EUV Irradiances, a physics based ionospheric model (TDIM), and 50 plus years of ionospheric observation from Wallops Island (Virginia) the above Sun-Earth ionospheric relationship will be reported on.

  19. A New Look at Solar Irradiance Variation

    NASA Astrophysics Data System (ADS)

    Foukal, Peter

    2012-08-01

    We compare total solar irradiance (TSI) and ultraviolet ( F uv) irradiance variation reconstructed using Ca K facular areas since 1915, with previous values based on less direct proxies. Our annual means for 1925 - 1945 reach values 30 - 50 % higher than those presently used in IPCC climate studies. A high facula/sunspot area ratio in spot cycles 16 and 17 seems to be responsible. New evidence from solar photometry increases the likelihood of greater seventeenth century solar dimming than expected from the disappearance of magnetic active regions alone. But the large additional brightening in the early twentieth century claimed from some recent models requires complete disappearance of the magnetic network. The network is clearly visible in Ca K spectroheliograms obtained since the 1890s, so these models cannot be correct. Changes in photospheric effective temperature invoked in other models would be powerfully damped by the thermal inertia of the convection zone. Thus, there is presently no support for twentieth century irradiance variation besides that arising from active regions. The mid-twentieth century irradiance peak arising from these active regions extends 20 years beyond the early 1940s peak in global temperature. This failure of correlation, together with the low amplitude of TSI variation and the relatively weak effect of Fuv driving on tropospheric temperature, limits the role of solar irradiance variation in twentieth century global warming.

  20. Electron irradiation of modern solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.

    1977-01-01

    A number of modern solar cell types representing 1976 technology (as well as some older types) were irradiated with 1 MeV electrons (and a limited number with 2 MeV electrons and 10 MeV protons). After irradiation, the cells were annealed, with I-V curves measured under AMO at 30 C. The purpose was to provide data to be incorporated in the revision of the solar cell radiation handbook. Cell resistivities ranged from 2 to 20 ohm-cm, and cell thickness from 0.05 to 0.46 mm. Cell types examined were conventional, shallow junction, back surface field (BSF), textured, and textured with BSF.

  1. Calibration of the Odyssey Photosynthetic Irradiance Recorder for Absolute Irradiance Measures

    EPA Science Inventory

    Researchers are increasingly interested in measuring hotosynthetically active radiation (PAR) because of its importance in determining the structure and function of lotic ecosystems. The Odyssey Photosynthetic Irradiance Recorder is an affordable PAR meter gaining popularity am...

  2. Solar Irradiance and Thermospheric Airglow Rocket Experiments

    NASA Astrophysics Data System (ADS)

    Solomon, Stanley C.

    1998-01-01

    This report describes work done in support of the Solar Irradiance and Thermospheric Air-glow Rocket Experiments at the University of Colorado for NASA grant NAG5-5021 under the direction of Dr. Stanley C. Solomon. (The overall rocket program is directed by Dr. Thomas N. Woods, formerly at the National Center for Atmospheric Research, and now also at the University of Colorado, for NASA grant NAG5-5141.) Grant NAG5-5021 provided assistance to the overall program through analysis of airglow and solar data, support of two graduate students, laboratory technical services, and field support. The general goals of the rocket program were to measure the solar extreme ultraviolet spectral irradiance, measure the terrestrial far-ultraviolet airglow, and analyze their relationship at various levels of solar activity, including near solar minimum. These have been met, as shown below. In addition, we have used the attenuation of solar radiation as the rocket descends through the thermosphere to measure density changes. This work demonstrates the maturity of the observational and modeling methods connecting energetic solar photon fluxes and airglow emissions through the processes of photoionization and photoelectron production and loss. Without a simultaneous photoelectron measurement, some aspects of this relationship remain obscure, and there are still questions pertaining to cascade contributions to molecular and atomic airglow emissions. However, by removing the solar irradiance as an "adjustable parameter" in the analysis, significant progress has been made toward understanding the relationship of far-ultraviolet airglow emissions to the solar and atmospheric conditions that control them.

  3. Accuracies of Incoming Radiation: Calibrations of Total Solar Irradiance Instruments

    NASA Astrophysics Data System (ADS)

    Kopp, G.; Harber, D.; Heuerman, K.

    2009-04-01

    All of the energy tracked by the GEWEX Radiative Flux Assessment and the driving energy for Earth climate is incident at the top of the Earth's atmosphere as solar radiation. The total solar irradiance (TSI) has been monitored continually for over 30 years from space. Continuity of these measurements has enabled the creation of composite time series from which the radiative forcing inputs to climate models are derived and solar forcing sensitivities are determined. None of the ten spaceborne TSI instruments contributing to the solar climate data record have been calibrated or validated end-to-end for irradiance accuracy under flight-like conditions, and calibration inaccuracies contribute to seemingly large offsets between the TSI values reported by each instrument. The newest of the flight TSI instruments, the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor (TIM), measures lower solar irradiance than prior instruments. I will review the accuracies of flight TSI instruments, discuss possible causes for the offsets between them, and describe a recently built calibration facility to improve the accuracies of future TSI instruments. The TSI Radiometer Facility (TRF) enables end-to-end comparisons of TSI instruments to a NIST-calibrated cryogenic radiometer. For the first time, TSI instruments can be validated directly against a cryogenic radiometer under flight-like conditions for measuring irradiance (rather than merely optical power) at solar power levels while under vacuum. The TRF not only validates TSI instrument accuracy, but also can help diagnose the causes of offsets between different instruments. This facility recently validated the accuracy of the TIM to be launched this year on NASA's Glory mission, establishing a baseline that can link the Glory/TIM to future TSI instruments via this ground-based comparison. Similar tests on the TRF with a ground-based SORCE/TIM support the lower TSI values measured by the SORCE flight unit. These

  4. Irradiation chemistry in the outer solar system

    NASA Astrophysics Data System (ADS)

    Brown, Michael E.

    2014-11-01

    The dark, reddish tinged surfaces of icy bodies in the outer solar are usually attributed to the long term irradiation of simple hydrocarbons such as methane leading to the loss of hydrogen and the production of long carbon chains. While methane is stable and detected on the most massive bodies in the Kuiper belt, evidence of active irradiation chemistry is scant except for the presence of ethane on methane-rich Makemake and possible detections of ethane on more methane-poor Pluto and Quaoar. We have obtained deep high signal-to-noise spectra of Makemake from 1.5 to 2.5 microns in an attempt to trace the radiation chemistry in the outer solar system beyond the initial ethane formation. We present the first astrophysical detections of solid ethylene, acetylene, and possibly propane -- all expected products of the continued irradiation of methane, and use these species to map the chemical pathway from methane to long-chain hydrocarbons.

  5. Solar cycle variation in UV solar spectral irradiance

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  6. Contributions of the Solar Ultraviolet Irradiance to the Total Solar Irradiance During Large Flares

    NASA Astrophysics Data System (ADS)

    Woods, T. N.; Kopp, G.

    2005-12-01

    The TIMED satellite was launched in December 2001 and the SORCE satellite was launched in January 2003. Since then the solar activity has evolved from solar maximum conditions to moderately low activity in 2005. The XUV Photometer System (XPS), aboard both TIMED and SORCE, is measuring the solar soft X-ray (XUV) irradiance shortward of 34 nm with 7-10 nm spectral resolution and the bright hydrogen emission at 121.5 nm. The XPS instrument is best known for observing over 200 flares during the TIMED mission with its 3% solar observing duty cycle and over 800 flares during the SORCE mission with its 70% duty cycle. The XUV radiation, being mostly from coronal emissions, varies more than other wavelengths in the solar spectrum during a flare event, with each flare lasting from minutes to hours. The XPS measurements indicate variations by a factor of 50 for the largest flares during the October-November 2003 solar storm period and that the XUV variations can be as much as 20% of the total flare energy as determined from the total solar irradiance (TSI) measurements by the SORCE Total Irradiance Monitor (TIM). The flare variations of the solar XUV irradiance and TSI will be discussed in the context of the TIMED and SORCE missions and their relationship to the GOES X-ray flare measurements.

  7. Analysis of Cumulus Solar Irradiance Reflectance (CSIR) Events

    NASA Technical Reports Server (NTRS)

    Laird, John L.; Harshvardham

    1996-01-01

    Clouds are extremely important with regard to the transfer of solar radiation at the earth's surface. This study investigates Cumulus Solar Irradiance Reflection (CSIR) using ground-based pyranometers. CSIR events are short-term increases in solar radiation observed at the surface as a result of reflection off the sides of convective clouds. When sun-cloud observer geometry is favorable, these occurrences produce characteristic spikes in the pyranometer traces and solar irradiance values may exceed expected clear-sky values. Ultraviolet CSIR events were investigated during the summer of 1995 using Yankee Environmental Systems UVA-1 and UVB-1 pyranometers. Observed data were compared to clear-sky curves which were generated using a third degree polynomial best-fit line technique. Periods during which the observed data exceeded this clear-sky curve were identified as CSIR events. The magnitude of a CSIR event was determined by two different quantitative calculations. The MAC (magnitude above clear-sky) is an absolute measure of the difference between the observed and clear-sky irradiances. Maximum MAC values of 3.4 Wm(exp -2) and 0.069 Wm(exp -2) were observed at the UV-A and UV-B wavelengths, respectively. The second calculation determined the percentage above clear-sky (PAC) which indicated the relative magnitude of a CSIR event. Maximum UV-A and UV-B PAC magnitudes of 10.1% and 7.8%, respectively, were observed during the study. Also of interest was the duration of the CSIR events which is a function of sun-cloud-sensor geometry and the speed of cloud propagation over the measuring site. In both the UV-A and UV-B wavelengths, significant CSIR durations of up to 30 minutes were observed.

  8. Analysis of cumulus solar irradiance reflectance (CSIR) events

    NASA Astrophysics Data System (ADS)

    Laird, John L.; Harshvardhan

    Clouds are extremely important with regard to the transfer of solar radiation at Earth's surface. This study investigates Cumulus Solar Irradiance Reflection (CSIR) using ground-based pyranometers. CSIR events are short-term increases in solar radiation observed at the surface as a result of reflection off the sides of convective clouds. When Sun-cloud observer geometry is favorable, these occurrences produce characteristic spikes in the pyranometer traces and solar irradiance values may exceed expected clear-sky values. Ultraviolet CSIR events were investigated during the summer of 1995 using UVA and UVB pyranometers. Observed data were compared to clear-sky curves which were generated using a third degree polynomial best-fit line technique. Periods during which the observed data exceeded this clear-sky curve were identified as CSIR events. The magnitude of a CSIR event was determined by two different quantitative calculations. The MAC (magnitude above clear-sky) is an absolute measure of the difference between the observed and clear-sky irradiances. Maximum MAC values of 3.4 Win -2 and 0.0169 Wm -2 were observed at the UV-A and UV-B wavelengths, respectively. The second calculation determined the percentage above clear-sky (PAC) which indicated the relative magnitude of a CSIR event. Maximum UV-A and UV-B PAC magnitudes of 10.1% and 7.8%, respectively, were observed during the study. Also of interest was the duration of the CSIR events which is a function of Sun-cloud-sensor geometry and the speed of cloud propagation over the measuring site. In both the UV-A and UV-B wavelengths, significant CSIR durations of up to 30 minutes were observed. C 1997 Elsevier Science B.V.

  9. Solar Ultraviolet Irradiance Variability During the Decline of Cycle 23

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Observations from the SOLar-STellar Irradiance Comparision Experiment (SOLSTICE) on the SOlar Radiation and Climate Experiment (SORCE) began in 2003 and continue through the present. This time period includes the decline of solar cycle 23 through solar minimum. SOLSTICE measures solar irradiance from 115 nm to 300 nm with a spectral resolution of 0.1 nm. The variability seen by SORCE SOLSTICE is greater than the variability recorded by the instruments on the Upper Atmosphere Research Satellite(UARS). This poster will describe the magnitude and uncertainty of solar irradiance variability in the ultraviolet part of the spectrum during the SORCE mission with comparisons to irradiance models based on UARS measurements.

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

    PubMed Central

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

    2015-01-01

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

  11. The effects of sunspots on solar irradiance

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.; Silva, S.; Woodard, M.; Willson, R. C.

    1982-01-01

    It is pointed out that the darkness of a sunspot on the visible hemisphere of the sun will reduce the solar irradiance on the earth. Approaches are discussed for obtaining a crude estimate of the irradiance deficit produced by sunspots and of the total luminosity reduction for the whole global population of sunspots. Attention is given to a photometric sunspot index, a global measure of spot flux deficit, and models for the compensating flux excess. A model is shown for extrapolating visible-hemisphere spot areas to the invisible hemisphere. As an illustration, this extrapolation is used to calculate a very simple model for the reradiation necessary to balance the flux deficit.

  12. Estimating Ultraviolet Solar Irradiance from Total Solar Irradiance: A Nine City Comparison

    NASA Astrophysics Data System (ADS)

    Clark, Eugene

    2010-10-01

    This paper presents new empirical equations that estimate hourly solar ultraviolet irradiance from the measured total solar irradiance and the solar zenith angle. These equations are based on data taken in 4 US cities (San Antonio, TX, Atlanta, GA, Albany, NY and Fairbanks, AK). Data taken in all 4 of these US cities utilized Eppley model PSP and TUVR radiometers. The response of the TUVR is dominated by UVA, but also includes some of the UVB region of the spectrum. The empirical equations based on the US data are compared with previously published equations based on data measured in 4 cities in Spain and one city in northern China. In all nine cities, the UV fraction of the total solar irradiance increases from about 4% under cloud free conditions to about 8% under heavily overcast conditions.

  13. Total Solar Irradiance: Present status of TSI observations

    NASA Astrophysics Data System (ADS)

    Schmutz, Werner; Fehlmann, Andr; Finsterle, Wolfgang; Rozanov, Eugene

    Total Solar Irradiance is measured by pyrheliometers. These instruments are either fully charac-terized and measure in absolute units or they are traceable to the World Radiometric Reference (WRR) at the World Radiation Center in Davos. The WRR in turn is so far only traceable to SI in power but not in irradiance. The added difficulty when discussing metrology of pyrheliome-ters in space is that the WRR is operated in air. Thus, so far, measurements of TSI in space rely on the full characterization of the instruments and a fully traceable TSI measurements has not yet been flown. This talk will give an overview over existing space observations of TSI and discusses the dif-ferences in the absolute and relative values between the various experiments. The challenge for future experiments is to get full traceability of the measurements in space. There are two upcoming experiments, PREMOS on PICARD and GLORY/TIM, which will yield TSI measurements which will be SI traceable.

  14. Solar variability in irradiance and oscillations

    NASA Technical Reports Server (NTRS)

    Kuhn, Jeff R.

    1995-01-01

    The signature of the solar cycle appears in helioseismic frequencies and splittings. It is known that the changing outer superadiabatic region of the sun is responsible for this. The deeper solar-cycle mechanism from the surface changes, and, in particular, how magnetic fields perturb the global modes, the solar irradiance and the luminosity, is discussed. The irradiance and helioseismic changes are described. The interpretation of seismic and photometric data is discussed, considering current one-dimensional models and phenomenology. It is discussed how the long term solar-cycle luminosity effect could be caused by changes occurring near the base of the convection zone (CZ). It is shown that a thin toroidal flux sheath at the top of the radiative zone changed the thermal stratification immediately below the CZ over a solar-cycle timescale in two ways: the temperature of the magnetized fluid becomes hotter than the surrounding fluid, and the temperature gradient steepens above the magnetized region. The testing of CZ dynamics and extension of numerical experiments to global scales are considered.

  15. Solar Irradiance, Plage and SOHO UV Images

    NASA Astrophysics Data System (ADS)

    Lopresto, James C.; Manross, Kevin

    1996-05-01

    Calcium K and H alpha plage and sunspot area have been monitored using Big Bear Observatory images on the INTERNET since November of 1992. The purpose of the project is to determine the correlation of changing plage area and solar irradiance changes. We also monitor changes in the K2 spec- tral index provided daily from Sacramento Peak. With the recent launching of the SOHO satellite, we are able to monitor the plage in the He II 304 Angstroms UV image. This image is near the top of the chromosphere nar or just under the transition region. The images show limb brightening as expected. Since it is widely believed that short time scale changes in the UV may be the dominant cause for low amplitude solar irradiance changes, the comparison of the "plage" ara in these UV images to those in conventional visible images should prove instructive.

  16. Fall 2010 Total Solar Irradiance Calibration Workshop

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; Socker, D. G.; Willson, R. C.; Kopp, G.

    2010-12-01

    As part of a NASA-Sponsored program to understand the differences in Total Solar Irradiance (TSI) results reported by various space-based radiometers, the Naval Research Laboratory is hosting a Total Solar Irradiance Calibration Workshop. This workshop is a follow-on meeting to a similar workshop hosted by the National Institute for Standards and Technology in 2005. These workshops have been attended by many of the PI teams of the past and current TSI measuring instruments. The discussions at these workshops have addressed calibration methods and the numerous instrumental differences that need to be understood in order to bring the complete ensemble of results onto a common scale. In this talk we will present an overview of the NRL Calibration Workshop which will include results of recent calibration studies at various laboratories and have involved several TSI instruments.

  17. Electron irradiation of tandem junction solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.; Scott-Monck, J. A.

    1979-01-01

    The electrical behavior of 100 micron thick tandem junction solar cells manufactured by Texas Instruments was studied as a function of 1 MeV electron fluence, photon irradiation, and 60 C annealing. These cells are found to degrade rapidly with radiation, the most serious loss occurring in the blue end of the cell's spectral response. No photon degradation was found to occur, but the cells did anneal a small amount at 60 C.

  18. Long-term variations in total solar and UV irradiances

    NASA Technical Reports Server (NTRS)

    Pap, J. M.; Floyd, L.; Lee, R. B.; Parker, D.; Puga, L.; Ulrich, R.; Varadi, F.; Viereck, R.

    1997-01-01

    The variations of total solar and UV irradiances during solar cycles 21 and 22 are compared. The total solar irradiance data used were obtained by the SMM/active cavity radiometer irradiance monitoring (ACRIM) 1, upper atmosphere research satellite (UARS)/ACRIM 2 and ERBS experiments. The space-based irradiance observations are compared to the Mount Wilson Magnetic Plage and Photometric Sunspot Index, which is derived from the area and position of sunspots published by the NOAA World Data Center Solar Geophysical Data Catalog. It is found that the variations in solar UV irradiance were similar during the maximum and minimum of solar cycles 21 and 22. The possible reasons for the differences in the irradiance values during the minima of the two solar cylces are discussed.

  19. Solar Irradiance: Recent Results and Future Research Plans

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.

    2009-05-01

    The solar irradiance, being the radiance integrated over the full disk, is the primary energy input for Earth's environment. Understanding the solar input is key for several terrestrial research topics concerning, to name a few, atmospheric ozone photochemistry, natural forcings on climate change, and improving space weather forecasting. From a solar physics viewpoint, the solar irradiance offers interesting challenges on understanding the sources of the variability of the solar irradiance, which has a strong dependence in wavelength and varies over all time periods from seconds to centuries. Recent solar irradiance results from the TIMED and SORCE satellite missions, such as concerning the current solar cycle minimum, will be presented. In addition, some outstanding questions for solar irradiance research will be addressed within the context of how they can be answered with the new missions, SDO, Glory, and PICARD, that are expected to be launched in late 2009.

  20. Photometric quantities for solar irradiance modeling

    NASA Astrophysics Data System (ADS)

    Preminger, D. G.; Walton, S. R.; Chapman, G. A.

    2002-11-01

    We analyze photometric quantities for the modeling of the total solar irradiance, S. These quantities are derived from full-disk solar images taken at the San Fernando Observatory. We introduce a new quantity, the photometric sum, Σ, which is the sum over an entire image of each pixel's contribution to the irradiance in that image. Σ combines both bright and dark features; and because the sum is over the entire image, it will include low contrast features that cannot be identified directly. Specifically, we examine Σr, Σb, and ΣK, the photometric sums over broadband red, broadband blue, and 1-nm bandpass Ca II K images, respectively. Σr and Σb measure the effects of solar features on the variability in S at two different continuum wavelengths. ΣK measures the variability in spectral lines due to solar features. We find that Σr and Σb have no long-term trend. ΣK, however, varies in phase with the solar cycle. We carry out several multiple linear regressions on the value of S from cycle 22; the best fit uses Σr and ΣK and reproduces the observed composite S with a multiple regression coefficient R = 0.96. We conclude that the long-term change in S over the solar cycle can be accounted for by the variability in the spectral lines as measured by ΣK, assuming no change in the quiet Sun; the contribution of the continuum to the variations in S is only on active region timescales.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  2. Solar Irradiance Data Products at the LASP Interactive Solar IRradiance Datacenter (LISIRD)

    NASA Astrophysics Data System (ADS)

    Ware Dewolfe, A.; Wilson, A.; Lindholm, D. M.; Pankratz, C. K.; Snow, M. A.; Woods, T. N.

    2010-12-01

    The Laboratory for Atmospheric and Space Physics (LASP) has developed the LASP Interactive Solar IRradiance Datacenter (LISIRD) to provide access to a comprehensive set of solar irradiance measurements. LISIRD has recently been updated to serve many new datasets and models, including data from SORCE, UARS-SOLSTICE, SME, and TIMED-SEE, and model data from the Flare Irradiance Spectral Model (FISM). The user interface emphasizes web-based interactive visualizations, allowing users to explore and compare this data before downloading it for analysis. The data provided covers a wavelength range from soft X-ray (XUV) at 0.1 nm up to the near infrared (NIR) at 2400 nm, as well as wavelength-independent Total Solar Irradiance (TSI). Combined data from the SORCE, TIMED-SEE, UARS-SOLSTICE, and SME instruments provide continuous coverage from 1981 to the present, while Lyman-alpha measurements, FISM daily data, and TSI models date from the 1940s to the present. LISIRD will also host Glory TSI data as part of the SORCE data system. This poster provides an overview of the LISIRD system, summarizes the data sets currently available, describes future plans and capabilities, and provides details on how to access solar irradiance data through LISIRD’s interfaces.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  5. Multivariate Analysis of Solar Spectral Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Pilewskie, P.; Rabbette, M.

    2001-01-01

    Principal component analysis is used to characterize approximately 7000 downwelling solar irradiance spectra retrieved at the Southern Great Plains site during an Atmospheric Radiation Measurement (ARM) shortwave intensive operating period. This analysis technique has proven to be very effective in reducing a large set of variables into a much smaller set of independent variables while retaining the information content. It is used to determine the minimum number of parameters necessary to characterize atmospheric spectral irradiance or the dimensionality of atmospheric variability. It was found that well over 99% of the spectral information was contained in the first six mutually orthogonal linear combinations of the observed variables (flux at various wavelengths). Rotation of the principal components was effective in separating various components by their independent physical influences. The majority of the variability in the downwelling solar irradiance (380-1000 nm) was explained by the following fundamental atmospheric parameters (in order of their importance): cloud scattering, water vapor absorption, molecular scattering, and ozone absorption. In contrast to what has been proposed as a resolution to a clear-sky absorption anomaly, no unexpected gaseous absorption signature was found in any of the significant components.

  6. Solar Spectral Irradiance Changes during Cycle 24

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  7. Solar Spectral Irradiance Changes During Cycle 24

    NASA Technical Reports Server (NTRS)

    Marchenko, Sergey; Deland, Matthew

    2014-01-01

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

  8. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (Editor); Chapman, G. A. (Editor); Hudson, H. S. (Editor); Willson, R. C. (Editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Solar irradiance observed from PVO and inferred solar rotation

    NASA Astrophysics Data System (ADS)

    Wolff, Charles L.; Hoegy, Walter R.

    1990-08-01

    Solar irradiance in the extreme ultraviolet flux (EUV) has been monitored for 11 years by the Pioneer Venus Orbiter (PVO). Since the experiment moves around the Sun with the orbital rate of Venus rather than that of Earth, the measurement gives us a second viewing location from which to begin unravelling which irradiance variations are intrinsic to the Sun, and which are merely rotational modulations whose periods depend on the motion of the observer. Researchers confirm an earlier detection, made with only 8.6 years of data, that the EUV irradiance is modulated by rotation rates of two families of global oscillation modes. One family is assumed to be r-modes occupying the convective envelope and sharing its rotation, while the other family (g-modes) lies in the radiative interior which as a slower rotation. Measured power in r-modes of low angular harmonic number indicates that the Sun's envelope rotated about 0.7 percent faster near the last solar maximum (1979 thru 1982) than it did during the next rise to maximum (1986 to 1989). No change was seen in the g-mode family of lines, as would be expected from the much greater rotational inertia of the radiative interior.

  11. A new observational solar irradiance composite

    NASA Astrophysics Data System (ADS)

    Schoell, Micha; Dudok de Wit, Thierry; Haberreiter, Margit; Kretzschmar, Matthieu; Misios, Stergios; Tourpali, Klairie; Schmutz, Werner

    2016-04-01

    Variations of the spectral solar irradiance (SSI) are an important driver for the chemistry, temperature and dynamics of the Earth's atmosphere and ultimately the Earth's climate. Due to the sparce and scattered SSI data sets it is important to establish tools to derive a consistent SSI dataset, including realistic uncertainties. We present the a new SSI composite based on the face values of SSI observations and applying a probabilistic method that takes into account the uncertainty of the data set scale-wise. We will present the data set and discuss its effects on the Earth's atmosphere in relation to SSI reconstruction models.

  12. Solar spectral irradiance and atmospheric transmission at Mauna Loa Observatory.

    PubMed

    Shaw, G E

    1982-06-01

    A radiometer was operated at the Mauna Loa Observatory during calendar year 1980 to estimate the spectral irradiance of the sun and its possible fluctuation in time near the peak of solar activity. Data were also acquired on seasonal trends of atmospheric transmissivity above the marine mixing layer in the central Pacific. Spectral irradiance remained constant to at least (1/2)% at all wavelengths monitored. Furthermore its absolute magnitude was in agreement with the Labs and Neckel values to +/-2% except at blue wavelengths where the Mauna Loa values are from 4 to 12% higher and at lambda = 850 nm where the Mauna Loa value is 9% lower. The residual aerosol optical depth above Mauna Loa Observatory during 1980 averaged tau(0) = 0.020. An intrusion of dust into the central Pacific from the Gobi Desert (as deduced by the composition of collected particles) invaded the Central Pacific from Mar. to May 1980 and caused a perturbation in optical depth (at lambda = 500 nm) of Deltatau(0) ~ 0.01-0.02. The optical depth increment caused by the Mt. St. Helens volcano was <0.005 in the 2-month period following the eruption. PMID:20389986

  13. Solar spectral irradiance and atmospheric transmission at Mauna Loa Observatory

    SciTech Connect

    Shaw, G.E.

    1982-06-01

    A radiometer was operated at the Mauna Loa Observatory during calendar year 1980 to estimate the spectral irradiance of the sun and its possible fluctuation in time near the peak of solar activity. Data were also acquired on seasonal trends of atmospheric transmissivity above the marine mixing layer in the central Pacific. Spectral irradiance remained c constant to at least 1/2% at all wavelengths monitored. Furthermore its absolute magnitude was in agreement with the Labs and Neckel values to +- 2% except at blue wavelengths where the Mauna Loa values are from 4 to 12% higher and at lambda = 850 nm where the Mauna Loa value is 9% lower. The residual aerosol optical depth above Mauna Loa Observatory during 1980 averaged tau/sub 0/ = 0.020. An intrusion of dust into the central Pacific from the Gobi Desert (as deduced by the composition of collected particles) invaded the Central Pacific from Mar. to May 19890 and caused a perturbation in optical depth (at lambda = 500 nm) of ..delta..tau/sub 0/approx.0.01--0.02. The optical depth increment caused by the Mt. St. Helens volcano was <0.005 in the 2-month period following the eruption.

  14. Direct solar spectral irradiance and transmittance measurements from 350 to 2500 nm.

    PubMed

    Kindel, B C; Qu, Z; Goetz, A F

    2001-07-20

    A radiometrically stable, commercially available spectroradiometer was used in conjunction with a simple, custom-designed telescope to make spectrally continuous measurements of solar spectral transmittance and directly transmitted solar spectral irradiance. The wavelength range of the instrument is 350-2500 nm and the resolution is 3-11.7 nm. Laboratory radiometric calibrations show the instrument to be stable to better than 1.0% over a nine-month period. The instrument and telescope are highly portable, can be set up in a matter of minutes, and can be operated by one person. A method of absolute radiometric calibration that can be tied to published top-of-the-atmosphere (TOA) solar spectra in valid Langley channels as well as regions of strong molecular absorption is also presented. High-altitude Langley plot calibration experiments indicate that this technique is limited ultimately by the current uncertainties in the TOA solar spectra, approximately 2-3%. Example comparisons of measured and modtran-modeled direct solar irradiance show that the model can be parameterized to agree with measurements over the large majority of the wavelength range to the 3% level for the two example cases shown. Side-by-side comparisons with a filter-based solar radiometer are in excellent agreement, with a mean absolute difference of tau = 0.0036 for eight overlapping wavelengths over three experiment days. PMID:18360373

  15. Long-term Solar Irradiance Variability: 1984-1989 Observations

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III

    1990-01-01

    Long-term variability in the total solar irradiance has been observed in the Earth Radiation Budget Experiment (ERBE) solar monitor measurements. The monitors have been used to measure the irradiance from the Earth Radiation Budget Satellite (ERBS) and the National Oceanic and Atmospheric Administration NOAA-9 and NOAA-10 spacecraft platforms since October 25, 1984, January 23, 1985, and October 22, 1986, respectively. Before September 1986, the ERBS irradiance values were found to be decreasing -0.03 percent per year. This period was marked by decreasing solar magnetic activity. Between September 1986 and mid-1989, the irradiance values increased approximately 0.1 percent. The latter period was marked by increasing solar activity which was associated with the initiations of the sunspot cycle number 22 and of a new 22-year Hale solar magnetic cycle. Therefore, long-term solar-irradiance variability appears to be correlated directly with solar activity. The maximum smoothed sunspot number occurred during September 1989, according to the Sunspot Index Data Center. Therefore, the recent irradiance increasing trend should disappear during early 1990 and change into a decreasing trend if the observed irradiance variability is correlated more so with the 11-year sunspot cycle than the 22-year Hale cycle. The ERBE irradiance values are presented and compared with sunspot activity for the 1984 to 1989 period. The ERBE values are compared with those available from the Nimbus-7 and Solar Maximum Mission spacecraft experiments.

  16. Application of Singular Spectrum Analysis to Solar Irradiance Variability

    NASA Technical Reports Server (NTRS)

    Pap, Judit M.; Varadi, Ferenc

    1995-01-01

    Studies of solar variability improve our knowledge of the internal structure and dynamical processes taking place within the Sun that lead to solar irradiance changes. Becuase of the astrophysical and climatic significance of irradiance variability, considerable effort has been devoted to model and understand its physical origin.

  17. Solar irradiance variations due to active regions

    SciTech Connect

    Oster, L.; Schatten, K.H.; Sofia, S.

    1982-05-15

    We have been able to reproduce the variations of the solar irradiance observed by ACRIM to an accuracy of better than +- 0.4 W m/sup -2/, assuming that during the 6 month observation period in 1980 the solar luminosity was constant. The improvement over previous attempts is primarily due to the inclusion of faculae. The reproduction scheme uses simple geometrical data on spot and facula areas, and conventional parameters for the respective fluxes and angular dependencies. The quality of reproduction is not very sensitive to most of the details of these parameters; nevertheless, there conventional parameters cannot be very different from their actual values in the solar atmosphere. It is interesting that the time average of the integrated excess emission (over directions) of the faculae cancels out the integrated deficit produced by the spots, within an accuracy of about 10%. If this behavior were maintained over longer periods of time, say, on the order of an activity cycle, active regions could be viewed as a kind of lighthouse where the energy deficit near the normal direction, associated with the spots, is primarily reemitted close to the tangential directions by the faculae. The currently available data suggest that energy ''storage'' associated with the redirection of flux near active regions on the Sun is comparable to the lifetime of the faculae.

  18. Modelling rotational and cyclical spectral solar irradiance variations

    NASA Astrophysics Data System (ADS)

    Unruh, Yvonne

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

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  20. Solar total irradiance in cycle 23

    NASA Astrophysics Data System (ADS)

    Krivova, N. A.; Solanki, S. K.; Schmutz, W.

    2011-05-01

    Context. The most recent minimum of solar activity was deeper and longer than the previous two minima as indicated by different proxies of solar activity. This is also true for the total solar irradiance (TSI) according to the PMOD composite. Aims: The apparently unusual behaviour of the TSI has been interpreted as evidence against solar surface magnetism as the main driver of the secular change in the TSI. We test claims that the evolution of the solar surface magnetic field does not reproduce the observed TSI in cycle 23. Methods: We use sensitive, 60-min averaged MDI magnetograms and quasi-simultaneous continuum images as an input to our SATIRE-S model and calculate the TSI variation over cycle 23, sampled roughly every two weeks. The computed TSI is then compared with the PMOD composite of TSI measurements and with the data from two individual instruments, SORCE/TIM and UARS/ACRIM II, that monitored the TSI during the declining phase of cycle 23 and over the previous minimum in 1996, respectively. Results: Excellent agreement is found between the trends shown by the model and almost all sets of measurements. The only exception is the early, i.e. 1996 to 1998, PMOD data. Whereas the agreement between the model and the PMOD composite over the period 1999-2009 is almost perfect, the modelled TSI shows a steeper increase between 1996 and 1999 than implied by the PMOD composite. On the other hand, the steeper trend in the model agrees remarkably well with the ACRIM II data. A closer look at the VIRGO data, which are the basis of the PMOD composite after 1996, reveals that only one of the two VIRGO instruments, the PMO6V, shows the shallower trend present in the composite, whereas the DIARAD measurements indicate a steeper trend. Conclusions: Based on these results, we conclude that (1) the sensitivity changes of the PMO6V radiometers within VIRGO during the first two years have very likely not been correctly evaluated; and that (2) the TSI variations over cycle 23

  1. Long-term variations in total solar irradiance

    NASA Technical Reports Server (NTRS)

    Pap, Judit M.; Willson, Richard C.; Froelich, Claus; Donnelly, Richard F.; Puga, Larry

    1994-01-01

    For more than a decade total solar irradiance has been monitored simultaneously from space by different satellites. The detection of total solar irradiance variations by satellite-based experiments during the past decade and a half has stimulated modeling efforts to help identify their causes and to provide estimates of irradiance data, using `proxy' indicators of solar activity, for time intervals when no satellite observations exist. In this paper total solar irradiance observed by the Nimbus-7/Earth Radiation Budget (ERB), Solar Maximum Mission (SMM)/Active Cavity Radiometer Irradiance Monitor (ACRIM) 1, and Upper Atmosphere Research Satellite (UARS)/ACRIM 2 radiometers is modeled with the Photometric Sunspot Index and the Mg II core-to-wing ratio. Since the formation of the Mg II line is very similar to that of the Ca II K line, the Mg core-to-wing ratio, derived from the irradiance observations of the Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements. It is shown that the observed changes in solar irradiance are underestimated by the proxy models at the time of maximum and during the beginning of the declining portion of solar cycle 22 similar to behavior just before the maximum of solar cycle 21. This disagreement between total irradiance observations and their model estimates is indicative of the fact that the underlying physical mechanism of the changes observed in the solar radiative output is not well-understood. Furthermore, the uncertainties in the proxy data used for irradiance modeling and the resulting limitation of the models should be taken into account, especially when the irradiance models are used for climatic studies.

  2. Space-based Observations of the Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.

    2015-08-01

    Solar photon radiation is the dominant energy input to the Earth system, and this energy determines the temperature, structure, and dynamics of the atmosphere, warms the Earth surface, and sustains life. Observations of true solar variability became possible only after attaining access to space, so the observational record of the solar irradiance for sun-climate studies extends back only about 40 years. The total solar irradiance (TSI) and solar spectral irradiance (SSI) observations will be presented along with the discussion of the solar variability during the past four decades. The solar radiation varies on all time scales ranging from minutes to hours for solar eruptive events (flares), days to months for active region evolution and solar rotation (~27 days), and years to decades over the solar activity cycle (~11 years). The amount of solar variability is highly dependent on wavelength and ranges from orders of magnitude for the X-ray to 10-60% for part of the ultraviolet to only 0.1% for the visible and infrared. The accuracy and precision of the solar irradiance measurements have steadily improved with each new generation of instrumentation and with new laboratory (pre-flight) calibration facilities.

  3. Solar irradiance dictates settlement timing and intensity of marine mussels

    PubMed Central

    Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X. Antón; Fernández-Reiriz, Mª José

    2016-01-01

    Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance. PMID:27384527

  4. Solar irradiance dictates settlement timing and intensity of marine mussels.

    PubMed

    Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X Antón; Fernández-Reiriz, M José

    2016-01-01

    Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance. PMID:27384527

  5. Solar resource assessment with a solar spectral irradiance meter

    NASA Astrophysics Data System (ADS)

    Tatsiankou, Viktar; Hinzer, Karin; Muron, Aaron; Haysom, Joan; Schriemer, Henry; Myrskog, Stefan

    2014-09-01

    The SSIM prototype was designed at the University of Ottawa as a cost-effective alternative to a field spectrora-diometer. The instrument was installed at the University of Ottawa's CPV testing facility in September, 2013, collecting the environmental and spectral data from October, 2013 to March, 2014. The SSIM's performance was compared against an ASD field spectroradiometer and an Eppley pyrheliometer during a six month study. It was observed that the SSIM can accurately reproduce the solar spectrum and the direct normal irradiance. The mean difference between the SSIM and the Eppley pyrheliometer was within ±1.5% for cloudless periods in October, 2013. However, bandpass filter degradation and moisture ingress limited the long term performance of the device.

  6. Modeling of the Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Shapiro, A.; Cessateur, G.; Dominique, M.; Krivova, N. A.; Lachat, D.; Rozanov, E.; Schmutz, W. K.; Shapiro, A. V.; Tagirov, R. V.; Thuillier, G. O.; Wehrli, C.

    2011-12-01

    Measurements and modeling of the solar irradiance have gained an increased attention during the last few decades. Nevertheless a complete picture of the solar variability is still missing. Therefore a launch of every new space mission devoted to the measurements of the spectral solar irradiance provides a crucial piece of complementary information and nourishes the theoretical models. We present here spectral solar irradiance data from the recent European missions PROBA-2 (launched on November 2, 2009) and PICARD (launched on June 15, 2010) and their theoretical interpretation. The PREMOS package onboard PICARD comprises two experiments, one observing solar irradiance in five (two UV, one visible and two near infrared) spectral channels with filter radiometers the other measuring TSI with absolute radiometers. LYRA is a solar VUV radiometer onboard PROBA-2, which is a technologically oriented ESA micro-mission, and is observing the solar irradiance in two UV and two EUV spectral channels. The passbands of the UV channels in the both experiments were selected on the ground of relevance for the terrestrial ozone concentration. The PREMOS and LYRA measurements were carefully corrected for the degradation and cleaned for non-solar signatures. We provide a comparison with the VIRGO/SOHO and SOLSTICE+SIM/SORCE data. Both LYRA and PREMOS have observed several solar eclipses. The analysis of these observations allows us to accurately retrieve the center-to-limb variations (CLV) of the solar brightness, which play an important role in the modeling of the solar irradiance variability on the time scale of the solar rotation. We show that the calculations with the recently developed and published COde for Solar Irradiance (COSI) yield the CLV which are in a good agreement with the measurements. The irradiance in all channels shows a clear variability on time-scale of the solar rotation. The amplitude and the profile of the variability strongly depend on the wavelength. We use

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  8. Magnitudes and timescales of total solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Kopp, Greg

    2016-07-01

    The Sun's net radiative output varies on timescales of minutes to gigayears. Direct measurements of the total solar irradiance (TSI) show changes in the spatially- and spectrally-integrated radiant energy on timescales as short as minutes to as long as a solar cycle. Variations of ~0.01% over a few minutes are caused by the ever-present superposition of convection and oscillations with very large solar flares on rare occasion causing slightly-larger measurable signals. On timescales of days to weeks, changing photospheric magnetic activity affects solar brightness at the ~0.1% level. The 11-year solar cycle shows variations of comparable magnitude with irradiances peaking near solar maximum. Secular variations are more difficult to discern, being limited by instrument stability and the relatively short duration of the space-borne record. Historical reconstructions of the Sun's irradiance based on indicators of solar-surface magnetic activity, such as sunspots, faculae, and cosmogenic isotope records, suggest solar brightness changes over decades to millennia, although the magnitudes of these variations have high uncertainties due to the indirect historical records on which they rely. Stellar evolution affects yet longer timescales and is responsible for the greatest solar variabilities. In this manuscript I summarize the Sun's variability magnitudes over different temporal regimes and discuss the irradiance record's relevance for solar and climate studies as well as for detections of exo-solar planets transiting Sun-like stars.

  9. A method to measure the broadband longwave irradiance in the terrestrial direct solar beam

    NASA Astrophysics Data System (ADS)

    Reda, Ibrahim; Konings, Jörgen; Xie, Yu

    2015-07-01

    Shortwave radiometers such as pyranometers, pyrheliometers, photovoltaic cells, and longwave radiometers such as pyrgeometers are calibrated with traceability to consensus References, which are maintained by Absolute Cavity Radiometers (ACRs) and the World InfraRed Standard Group (WISG), respectively. Since the ACR is an open cavity with no window, and was developed to measure the extended broadband spectrum of the terrestrial direct solar beam irradiance, then there would be discrepancy in calibrating the shortwave radiometers because of their limited spectral band. On the other hand, pyrgeometers are calibrated during the nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This article describes a method to measure the broadband longwave irradiance in the terrestrial direct solar beam from 3 μm to 50 μm. The method might be used in developing calibration methods to address the mismatch between the broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometer calibration. We used the described method to measure the irradiance from sunrise to sunset; the irradiance varied from approximately 1 W m-2 to 16 W m-2 with an estimated uncertainty of 1.46 W m-2, for a solar zenith angle range from 80° to 16°, respectively.

  10. Long-term downward trend in total solar irradiance

    SciTech Connect

    Willson, R.C.; Hudson, H.S.; Frohlich, C.; Brusa, R.W.

    1986-11-28

    The first 5 years (from 1980 to 1985) of total solar irradiance observations by the first Active Cavity Radiometer Irradiance Monitor (ACRIM I) experiment on board the Solar Maximum Mission spacecraft show a clearly defined downward trends of -0.019% per year. The existence of this trend has been confirmed by the internal self-calibrations of ACRIM I, by independent measurements from sounding rockets and balloons, and by observations from the Nimbus-7 spacecraft. The trend appears to be due to unpredicted variations of solar luminosity on time scales of years, and it may be related to solar cycle magnetic activity.

  11. Long-term downward trend in total solar irradiance.

    PubMed

    Willson, R C; Hudson, H S; Frohlich, C; Brusa, R W

    1986-11-28

    The first 5 years (from 1980 to 1985) of total solar irradiance observations by the first Active Cavity Radiometer Irradiance Monitor (ACRIM I) experiment on board the Solar Maximum Mission spacecraft show a clearly defined downward trend of -0.019% per year. The existence of this trend has been confirmed by the internal self-calibrations of ACRIM I, by independent measurements from sounding rockets and balloons, and by observations from the Nimbus-7 spacecraft. The trend appears to be due to unpredicted variations of solar luminosity on time scales of years, and it may be related to solar cycle magnetic activity. PMID:17778952

  12. Long-term reconstructions of total solar irradiance

    NASA Astrophysics Data System (ADS)

    Krivova, Natalie; Solanki, Sami K.; Dasi Espuig, Maria

    2012-07-01

    Solar irradiance is the main external driver of the Earth's climate, although its relative contribution compared to other internal and anthropogenic factors is not yet well determined. Variations of total solar irradiance have being measured for over three decades and are relatively well understood. Reconstructions of the irradiance into the past remain, however, rather uncertain. In particular, the magnitude of the secular change is highly debated. The reason is the lack of direct and well-sampled proxies of solar magnetic activity on time scales longer than a few decades. Reconstructions on time scales of centuries rely on sunspot observations available since 1610. Reconstructions on millennial time scales use concentrations of the cosmogenic isotopes in terrestrial archives. We will review long-term reconstructions of the solar irradiance using the SATIRE set of models, compare them with other recent models and discuss the remaining uncertainties.

  13. Atmosphere, Ocean, Land, and Solar Irradiance Data Sets

    NASA Technical Reports Server (NTRS)

    Johnson, James; Ahmad, Suraiya

    2003-01-01

    The report present the atmosphere, ocean color, land and solar irradiation data sets. The data presented: total ozone, aerosol, cloud optical and physical parameters, temperature and humidity profiles, radiances, rain fall, drop size distribution.

  14. The absolute chronology and thermal processing of solids in the solar protoplanetary disk.

    PubMed

    Connelly, James N; Bizzarro, Martin; Krot, Alexander N; Nordlund, Åke; Wielandt, Daniel; Ivanova, Marina A

    2012-11-01

    Transient heating events that formed calcium-aluminum-rich inclusions (CAIs) and chondrules are fundamental processes in the evolution of the solar protoplanetary disk, but their chronology is not understood. Using U-corrected Pb-Pb dating, we determined absolute ages of individual CAIs and chondrules from primitive meteorites. CAIs define a brief formation interval corresponding to an age of 4567.30 ± 0.16 million years (My), whereas chondrule ages range from 4567.32 ± 0.42 to 4564.71 ± 0.30 My. These data refute the long-held view of an age gap between CAIs and chondrules and, instead, indicate that chondrule formation started contemporaneously with CAIs and lasted ~3 My. This time scale is similar to disk lifetimes inferred from astronomical observations, suggesting that the formation of CAIs and chondrules reflects a process intrinsically linked to the secular evolution of accretionary disks. PMID:23118187

  15. A reconstruction of solar irradiance using a flux transport model

    NASA Astrophysics Data System (ADS)

    Dasi Espuig, Maria; Jiang, Jie; Krivova, Natalie; Solanki, Sami

    2013-04-01

    Reconstructions of solar irradiance into the past are of considerable interest for studies of solar influence on climate. Models based on the assumption that irradiance changes are caused by the evolution of the photospheric magnetic field have been the most successful in reproducing the measured irradiance variations. Our SATIRE-S model is one of these. It uses solar full-disc magnetograms as an input, and these are available for less than four decades. Thus, to reconstruct the irradiance back to times when no observed magnetograms are available, we combine the SATIRE-S model with synthetic magnetograms, produced using a surface flux transport model. The model is fed with daily, observed or modelled statistically, records of sunspot positions, areas, and tilt angles. To describe the secular change in the irradiance, we used the concept of overlapping ephemeral region cycles. With this technique TSI can be reconstructed back to 1610.

  16. Modelling total solar irradiance using a flux transport model

    NASA Astrophysics Data System (ADS)

    Dasi Espuig, Maria; Jiang, Jie; Krivova, Natalie; Solanki, Sami

    2014-05-01

    Reconstructions of solar irradiance into the past are of considerable interest for studies of solar influence on climate. Models based on the assumption that irradiance changes are caused by the evolution of the photospheric magnetic field have been the most successful in reproducing the measured irradiance variations. Our SATIRE-S model is one of these. It uses solar full-disc magnetograms as an input, and these are available for less than four decades. Thus, to reconstruct the irradiance back to times when no observed magnetograms are available, we combine the SATIRE-S model with synthetic magnetograms, produced using a surface flux transport model. The model is fed with daily, observed or modelled statistically, records of sunspot positions, areas, and tilt angles. To describe the secular change in the irradiance, we used the concept of overlapping ephemeral region cycles. With this technique TSI can be reconstructed back to 1700.

  17. The satellite total solar irradiance database

    NASA Astrophysics Data System (ADS)

    Willson, R. C.

    2009-12-01

    A precise knowledge of the total solar irradiance (TSI) over time is essential to understanding the physics of solar luminosity variation and its impact on the Earth in the form of climate change. A National Research Council study found that sustained trends as small as 0.25% per century were the most likely forcing for ‘little ice age’ climate minima during the 12th - 19th centuries. Recent phenomenological analyses of TSI observations and proxies indicate that TSI variation is an important climate change forcing on many timescales including the industrial era. The profound sociological and economic implications of understanding the relative climate change contributions of natural and anthropogenic forcings makes it essential that the satellite TSI database be precisely sustained into the foreseeable future. There are currently three satellite TSI monitoring experiments in operation: SOHO/VIRGO, ACRIMSAT/ACRIM3 and SORCE/TIM, in order of deployment (1996, 2000 and 2003, resp.). Results reported on their ‘native scales show the same basic variations in TSI over time, yet some smaller variations detected by ACRIM3 are less well defined or absent in the results of VIRGO and TIM. There is also a scale difference issue: TIM results are 0.35% lower than those of ACRIM3 and VIRGO, outside the ± 0.1% uncertainty bounds predicted for ACRIM3 and VIRGO, and well outside TIM’s ± 0.01% uncertainty design goal. TIM’s failure to achieve 0.01% uncertainty in flight demonstrates that the TSI monitoring paradigm shift of relying on measurement accuracy rather than a redundant/overlap strategy to provide long term traceability cannot be realized with current ‘ambient temperature’ technology. The only viable monitoring approach for the foreseeable future continues to be the redundant/overlap strategy that has provided the 31 year satellite TSI database to date with useful traceability. Intercomparisons of flight experiments at their levels of mutual precision can

  18. On the variation of the Nimbus 7 total solar irradiance

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1992-01-01

    For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.65 Wm(exp -2), a coefficient of variation (mean divided by the standard deviation) of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of -8.019 (inferring a highly significant non-random variation in the solar irradiance measurements, presumably related to the action of the solar cycle). Comparison of the 12-month moving average (also called the 13-month running mean) of solar irradiance to those of the usual descriptors of the solar cycle (i.e., sunspot number, 10.7-cm solar radio flux, and total corrected sunspot area) suggests possibly significant temporal differences. For example, solar irradiance is found to have been greatest on or before mid 1979 (leading solar maximum for cycle 21), lowest in early 1987 (lagging solar minimum for cycle 22), and was rising again through late 1990 (thus, lagging solar maximum for cycle 22), having last reported values below those that were seen in 1979 (even though cycles 21 and 22 were of comparable strength). Presuming a genuine correlation between solar irradiance and the solar cycle (in particular, sunspot number) one infers that the correlation is weak (having a coefficient of correlation r less than 0.84) and that major excursions (both as 'excesses' and 'deficits') have occurred (about every 2 to 3 years, perhaps suggesting a pulsating Sun).

  19. Open Surface Solar Irradiance Observations - A Challenge

    NASA Astrophysics Data System (ADS)

    Menard, Lionel; Nüst, Daniel; Jirka, Simon; Maso, Joan; Ranchin, Thierry; Wald, Lucien

    2015-04-01

    The newly started project ConnectinGEO funded by the European Commission aims at improving the understanding on which environmental observations are currently available in Europe and subsequently providing an informational basis to close gaps in diverse observation networks. The project complements supporting actions and networking activities with practical challenges to test and improve the procedures and methods for identifying observation data gaps, and to ensure viability in real world scenarios. We present a challenge on future concepts for building a data sharing portal for the solar energy industry as well as the state of the art in the domain. Decision makers and project developers of solar power plants have identified the Surface Solar Irradiance (SSI) and its components as an important factor for their business development. SSI observations are crucial in the process of selecting suitable locations for building new plants. Since in-situ pyranometric stations form a sparse network, the search for locations starts with global satellite data and is followed by the deployment of in-situ sensors in selected areas for at least one year. To form a convincing picture, answers must be sought in the conjunction of these EO systems, and although companies collecting SSI observations are willing to share this information, the means to exchange in-situ measurements across companies and between stakeholders in the market are still missing. We present a solution for interoperable exchange of SSI data comprising in-situ time-series observations as well as sensor descriptions based on practical experiences from other domains. More concretely, we will apply concepts and implementations of the Sensor Web Enablement (SWE) framework of the Open Geospatial Consortium (OGC). The work is based on an existing spatial data infrastructure (SDI), which currently comprises metadata, maps and coverage data, but no in-situ observations yet. This catalogue is already registered in the

  20. White Paper on SBUV/2 Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    The importance of solar irradiance measurements by the Solar Backscatter Ultraviolet, Model 2 (SBUV/2) instruments on NOAA's operational satellites is described. These measurements are necessary accurately monitor the long-term changes in the global column ozone amount, the altitude distribution of ozone in the upper stratosphere, and the degree to which ozone changes are caused by anthropogenic sources. Needed to accomplish these goals are weekly solar irradiance measurements at the operational ozone wavelengths, daily measurements of the Mg II proxy index, instrument-specific Mg II scale factors, and daily measurements of the solar spectral irradiance at photochemically important wavelengths. Two solar measurement schedules are provided: (1) a baseline schedule for all instruments except the NOAA-14 instrument and (2) a modified schedule for the NOAA-14 SBUV/2 instrument. This latter schedule is needed due to the NOAA-14 grating drive problems.

  1. Variations in solar Lyman alpha irradiance on short time scales

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1992-01-01

    Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

  2. First light measurements of the Total Solar Irradiance experiment CLARA on NORSAT-1

    NASA Astrophysics Data System (ADS)

    Schmutz, Werner

    2016-07-01

    NORSAT-1 is a Norwegian micro-satellite, which will be launched April 22, 2016. (In the future at the time of writing this abstract.) The satellite carries two scientific instruments and an AIS receiver for performing ship detection from space. One of the scientific instruments is a Compact Light-weight Absolute RAdiometer (CLARA) and the other is a Langmuir Probe instrument comprising four probes mounted on booms. The latter experiment will measure electron density and the platform's floating potential along the orbit. The University of Oslo provides the Langmuir probes. The radiometer experiment CLARA has been built by PMOD/WRC funded through the Swiss PRODEX program. It will measure Total Solar Irradiance with an instrument of novel design that is optimized for minimizing mass and size by still ensuring highest measuring accuracy and thermal stability. The radiometers of CLARA have been fully characterized as well as calibrated at the TRF facility. It is expected that the first light accuracy of the absolute measurement of Total Solar Irradiance will be better than pm0.3 W/m^{2, allowing to probe the current TSI composite for its absolute level. The presentation will give an overview of the CLARA instrument and its calibration. It is expected that at the time of the COSPAR conference the first light TSI value of CLARA/NORSAT-1 is ready for publication. Together with a previous absolute TSI measurements available for July 27, 2010 measured by PREMOS/PICARD the new absolute TSI measurement will be used to test the accuracy of long term TSI trend given by the relative TSI composite.

  3. Evaluation of solar irradiance models for climate studies

    NASA Astrophysics Data System (ADS)

    Ball, William; Yeo, Kok-Leng; Krivova, Natalie; Solanki, Sami; Unruh, Yvonne; Morrill, Jeff

    2015-04-01

    Instruments on satellites have been observing both Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI), mainly in the ultraviolet (UV), since 1978. Models were developed to reproduce the observed variability and to compute the variability at wavelengths that were not observed or had an uncertainty too high to determine an accurate rotational or solar cycle variability. However, various models and measurements show different solar cycle SSI variability that lead to different modelled responses of ozone and temperature in the stratosphere, mainly due to the different UV variability in each model, and the global energy balance. The NRLSSI and SATIRE-S models are the most comprehensive reconstructions of solar irradiance variability for the period from 1978 to the present day. But while NRLSSI and SATIRE-S show similar solar cycle variability below 250 nm, between 250 and 400 nm SATIRE-S typically displays 50% larger variability, which is however, still significantly less then suggested by recent SORCE data. Due to large uncertainties and inconsistencies in some observational datasets, it is difficult to determine in a simple way which model is likely to be closer to the true solar variability. We review solar irradiance variability measurements and modelling and employ new analysis that sheds light on the causes of the discrepancies between the two models and with the observations.

  4. Reconstructions of solar irradiance on centennial time scales

    NASA Astrophysics Data System (ADS)

    Krivova, Natalie; Solanki, Sami K.; Dasi Espuig, Maria; Kok Leng, Yeo

    Solar irradiance is the main external source of energy to Earth's climate system. The record of direct measurements covering less than 40 years is too short to study solar influence on Earth's climate, which calls for reconstructions of solar irradiance into the past with the help of appropriate models. An obvious requirement to a competitive model is its ability to reproduce observed irradiance changes, and a successful example of such a model is presented by the SATIRE family of models. As most state-of-the-art models, SATIRE assumes that irradiance changes on time scales longer than approximately a day are caused by the evolving distribution of dark and bright magnetic features on the solar surface. The surface coverage by such features as a function of time is derived from solar observations. The choice of these depends on the time scale in question. Most accurate is the version of the model that employs full-disc spatially-resolved solar magnetograms and reproduces over 90% of the measured irradiance variation, including the overall decreasing trend in the total solar irradiance over the last four cycles. Since such magnetograms are only available for about four decades, reconstructions on time scales of centuries have to rely on disc-integrated proxies of solar magnetic activity, such as sunspot areas and numbers. Employing a surface flux transport model and sunspot observations as input, we have being able to produce synthetic magnetograms since 1700. This improves the temporal resolution of the irradiance reconstructions on centennial time scales. The most critical aspect of such reconstructions remains the uncertainty in the magnitude of the secular change.

  5. Absolute high spectral resolution measurements of surface solar radiation for detection of water vapour continuum absorption.

    PubMed

    Gardiner, T D; Coleman, M; Browning, H; Tallis, L; Ptashnik, I V; Shine, K P

    2012-06-13

    Solar-pointing Fourier transform infrared (FTIR) spectroscopy offers the capability to measure both the fine scale and broadband spectral structure of atmospheric transmission simultaneously across wide spectral regions. It is therefore suited to the study of both water vapour monomer and continuum absorption behaviours. However, in order to properly address this issue, it is necessary to radiatively calibrate the FTIR instrument response. A solar-pointing high-resolution FTIR spectrometer was deployed as part of the 'Continuum Absorption by Visible and Infrared radiation and its Atmospheric Relevance' (CAVIAR) consortium project. This paper describes the radiative calibration process using an ultra-high-temperature blackbody and the consideration of the related influence factors. The result is a radiatively calibrated measurement of the solar irradiation at the ground across the IR region from 2000 to 10 000 cm(-1) with an uncertainty of between 3.3 and 5.9 per cent. This measurement is shown to be in good general agreement with a radiative-transfer model. The results from the CAVIAR field measurements are being used in ongoing studies of atmospheric absorbers, in particular the water vapour continuum. PMID:22547234

  6. 13 Years of SOHO/CELIAS/SEM Calibrated Solar Extreme Ultraviolet Irradiance Data

    NASA Astrophysics Data System (ADS)

    Judge, D.; Didkovsky, L.; Wieman, S.; Gangopadhyay, P.

    2008-12-01

    A verified and updated version of the calibrated SOHO/CELIAS/SEM (absolute) solar extreme ultraviolet (EUV) measurements from the beginning of the mission in 1996 through the present is available at the University of Southern California Space Sciences Center website. To complete this new version, six (1999- 2006) sounding rocket under-flights were analyzed using measurements from both a very stable Rare Gas (Ne) Ionization Cell (RGIC) and a clone of the flight SEM instrument. These sounding rocket under-flights have provided a number of reference points that have been compared with the solar flux data published on our web site (last revised in 2000). These reference points are in good agreement with the solar cycle EUV flux for the 30.4 nm first order (26 nm to 34 nm) SEM channels, indicating a very small (less than 1 percent) averaged difference from the published flux for the six under-flights. Thirteen years of continuous and accurate SEM data will continue to provide important information about short term (solar flares) and long term (solar cycle) changes of EUV solar irradiance, and will be used for advancing solar models, for more accurate Earth atmosphere drag models, ionization proxies, and atmospheric dynamics generally, and will also provide solar EUV measurement overlap with the new SDO Extreme ultraviolet Variability Experiment (EVE), to be launched in 2009.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  8. Computation of glint, glare, and solar irradiance distribution

    SciTech Connect

    Ho, Clifford Kuofei; Khalsa, Siri Sahib Singh

    2015-08-11

    Described herein are technologies pertaining to computing the solar irradiance distribution on a surface of a receiver in a concentrating solar power system or glint/glare emitted from a reflective entity. At least one camera captures images of the Sun and the entity of interest, wherein the images have pluralities of pixels having respective pluralities of intensity values. Based upon the intensity values of the pixels in the respective images, the solar irradiance distribution on the surface of the entity or glint/glare corresponding to the entity is computed.

  9. Long-term solar irradiance variability: knowns and unknowns

    NASA Astrophysics Data System (ADS)

    Krivova, Natalie; Solanki, Sami K.; Dasi Espuig, Maria; Leng Yeo, Kok; Wu, Chi-Ju

    2016-07-01

    Long-term reconstructions of solar irradiance variability are crucial to our understanding of solar influence on climate. They are only possible with the help of suitable models, which in turn require a thorough understanding of the mechanisms of this variability. With the advance of such models, also the past reconstructions are becoming more reliable. Nevertheless, the remaining uncertainties spread out when extrapolating back over long periods of time, amplified by the increasingly poorer quality and reliability of the available data that bear information on past solar activity. We will discuss the progress and the reliability of irradiance reconstructions on time scales of decades to millennia.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  11. Observed solar UV irradiance variations of importance to middle atmosphere energetics and photochemistry

    NASA Technical Reports Server (NTRS)

    London, Julius

    1994-01-01

    Absorption of solar UV irradiance in the spectral interval 120-420 nm is chiefly responsible for radiative heating and photodissociation of important atmospheric constituents (e.g., O2, O3, H2O, NO2, etc.) in the stratosphere, mesosphere, and lower thermosphere. Thus, the absolute value and time perturbations of the UV irradiance could significantly affect the energetics, photochemistry, and subsequent dynamics of these regions. Analysis of preliminary data from the SOLSTICE (UARS) observations for a period of 244 days (3 Oct 1991-2 Jun 1992) is discussed in this paper. The data provide mean daily values of the spectral distribution of the observed irradiances at 1-nm resolution and their solar rotation and semirotation variations. The average amplitudes of the 27-day irradiance oscillations for the 244-day data period were 5.7% at Lyman-alpha (121 nm), 1% at 200 nm, 0.5% at 210 nm, and generally less than 0.2% at wavelengths longer than 280 nm. The average amplitudes of 13.5-day oscillations were, by and large, about half of these values. Solar irradiance variations at 10.7 cm are highly correlated with those at Ly-alpha and other chromospheric emission lines (r = 0.7 to 0.8) and only moderately correlated with irradiances at wavelengths of 180-208 nm (r = 0.5). The correlation decreases as the source region of the irradiance gets closer to the base of the photosphere. At the 2-nm interval 279-281 nm, however, which contains the cores of the Mg II h and k lines, the correlation is again approximately 0.8.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  13. A reconstruction of solar irradiance using a flux transport model

    NASA Astrophysics Data System (ADS)

    Dasi Espuig, Maria; Krivova, Natalie; Solanki, Sami K.; Jiang, Jie

    2012-07-01

    Solar irradiance is one of the important drivers of the Earth's global climate, but it has only been measured for the past 33 years. Its reconstructions are therefore crucial to study longer term variations relevant to climate timescales. Most successful in reproducing the measured irradiance variations have being the models that are based on the assumption that irradiance changes are caused by the evolution of the photospheric magnetic field. Our SATIRE-S model is one of these, which uses solar full-disc magnetograms as an input, and these are available for less than four decades. To reconstruct the irradiance back to times when no observed magnetograms are available, we combine the SATIRE-S model with synthetic magnetograms, produced using a surface flux transport model. The model is fed with daily, observed or modelled statistically, records of sunspot positions, areas, and tilt angles. The concept of overlapping ephemeral region cycles is used to describe the secular change in the irradiance.

  14. Two-parameter model of total solar irradiance variation over the solar cycle

    NASA Technical Reports Server (NTRS)

    Pap, Judit M.; Willson, Richard C.; Donnelly, Richard F.

    1991-01-01

    Total solar irradiance measured by the SMM/ACRIM radiometer is modelled from the Photometric Sunspot Index and the Mg II core-to-wing ratio with multiple regression analysis. Considering that the formation of the Mg II line is very similar to that of the Ca II K line, the Mg II core-to-wing ratio, measured by the Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements, including faculae and the magnetic network. It is shown that the relationship between the variations in total solar irradiance and the above solar activity indices depends upon the phase of the solar cycle. Thus, a better fit between total irradiance and its model estimates can be achieved if the irradiance models are calculated for the declining portion and minimum of solar cycle 21, and the rising portion of solar cycle 22, respectively. There is an indication that during the rising portion of solar cycle 22, similar to the maximum time of solar cycle 21, the modelled total irradiance values underestimate the measured values. This suggests that there is an asymmetry in the long-term total irradiance variability.

  15. The solar irradiance registered at a flat- hemispherical field of view- bolometric oscillation sensor on board PICARD satellite

    NASA Astrophysics Data System (ADS)

    Zhu, Ping; Karatekin, Ozgur; van Ruymbeke, Michel; Dewitte, Steven; Thuillier, Gerard

    2014-05-01

    The value of the Total Solar Irradiance (TSI) is varying over the 11-year sunspot cycle. The cycle amplitude is about 0.1% solar constant, which could be traced with the absolute radiometers onboard dedicated space missions. The operating principle of the absolute radiometer is measuring the electrical heating power of the heat sensing unit during the closed and opened phase of each measurement cycle. The difference between the power integrated cross the closed phase and the power integrated cross the open phase gives the value of the solar irradiance. The cadence of the measurement is usually from one to several minutes. The final TSI value in physics unit is obtained after taking into account the electronic calibration, correction of the instruments effects, and normalizing to 1 AU. The Bolometric Oscillation Sensor on board PICARD microsatellite is a new designed remote sensing instrument. The BOS is operated continually with a 10 seconds cadence to fill the time gaps between open and close phases of the SOVAP absolute radiometer. The BOS has two sensing surfaces, the main one with a light mass is black coated, the second surface is white painted with a heavier mass. The sensor has a hemispherical field of view. The heat flux absorbed by the main detector is thermally conducted by a thin shunt to the heat sink. The principle of the measurements is that the sum of the power of the blacked coated surface and the power along the shunt is equal to the incoming electromagnetic radiation. However as the BOS has a HFOV, the incoming radiation caught by it, has three kinds of origin: the solar irradiance, the reflected solar visible light form the Earth and the terrestrial infrared radiation. In this work, we are going to discuss the solar irradiance isolated from the measurements of the BOS instrument as well as the comparison with the sunspot number and the TSI composite from the VIRGO/SOHO and TIM/SORCE experiments.

  16. LISIRD: Where to go for Solar Irradiance Data

    NASA Astrophysics Data System (ADS)

    Wilson, A.; Pankratz, C. K.; Lindholm, D. M.; Snow, M.; Knapp, B.; Woodraska, D.; Templeman, B.; Woods, T.; Eparvier, F.; Fontenla, J.; Harder, J.; Bill, M.

    2008-12-01

    LASP, the Laboratory for Atmospheric and Space Physics, has been providing web access to solar irradiance measurements, reference spectra, composites and model data covering the solar spectrum from .1 to 2400 nm through LISIRD, the LASP Interactive Solar IRradiance Datacenter. No single instrument can measure the solar spectral irradiance from X-rays to the IR, but the ensemble of LASP instruments can. LISIRD uses a single interface to provide easy, logical access to a variety of mission data, merged in time and wavelength. Daily space weather measurements are available, including total solar irradiance (TSI), Lyman Alpha (121 nm), Magnesium II Index (280 nm), He II (30.4 nm), FE XVI (33.5 nm), and the FUV continuum (145 to 165 nm). More recently, LISIRD has recently added the Whole Heliosphere Interval (WHI) Solar Irradiance time series, which provides a quiet sun reference spectra for the period of April 10-16 of 2008. LISIRD also recently added a composite solar spectral irradiance product over the range of 120 to 400 nm for the time period from November 8, 1978 to August 1, 2005. This product, created by Mathew Deland at SSAI, merges data from six different satellites into a single SSI product. And, we are currently adding a time series for daily solar spectral irradiance from 1950 to 2006, created by Judith Lean of the Naval Research Lab. This product adjusts observed irradiance for a given wavelength with parameters that represent known sources of variability at that wavelength. LISIRD remains committed to improving data access in a variety of ways. We are planning and developing a means for the broader community of scientists to easily determine data availability for a particular date range without having to know mission or instrument details. Improved data subsetting will allow users to request only the time range or spectra that users need, making data management generally easier. We expect to continue to enhance our data offerings. Future vision for

  17. Principal Component Analysis of Arctic Solar Irradiance Spectra

    NASA Technical Reports Server (NTRS)

    Rabbette, Maura; Pilewskie, Peter; Gore, Warren J. (Technical Monitor)

    2000-01-01

    During the FIRE (First ISCPP Regional Experiment) Arctic Cloud Experiment and coincident SHEBA (Surface Heat Budget of the Arctic Ocean) campaign, detailed moderate resolution solar spectral measurements were made to study the radiative energy budget of the coupled Arctic Ocean - Atmosphere system. The NASA Ames Solar Spectral Flux Radiometers (SSFRs) were deployed on the NASA ER-2 and at the SHEBA ice camp. Using the SSFRs we acquired continuous solar spectral irradiance (380-2200 nm) throughout the atmospheric column. Principal Component Analysis (PCA) was used to characterize the several tens of thousands of retrieved SSFR spectra and to determine the number of independent pieces of information that exist in the visible to near-infrared solar irradiance spectra. It was found in both the upwelling and downwelling cases that almost 100% of the spectral information (irradiance retrieved from 1820 wavelength channels) was contained in the first six extracted principal components. The majority of the variability in the Arctic downwelling solar irradiance spectra was explained by a few fundamental components including infrared absorption, scattering, water vapor and ozone. PCA analysis of the SSFR upwelling Arctic irradiance spectra successfully separated surface ice and snow reflection from overlying cloud into distinct components.

  18. Advanced solar irradiances applied to satellite and ionospheric operational systems

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent; Schunk, Robert; Eccles, Vince; Bouwer, Dave

    Satellite and ionospheric operational systems require solar irradiances in a variety of time scales and spectral formats. We describe the development of a system using operational grade solar irradiances that are applied to empirical thermospheric density models and physics-based ionospheric models used by operational systems that require a space weather characterization. The SOLAR2000 (S2K) and SOLARFLARE (SFLR) models developed by Space Environment Technologies (SET) provide solar irradiances from the soft X-rays (XUV) through the Far Ultraviolet (FUV) spectrum. The irradiances are provided as integrated indices for the JB2006 empirical atmosphere density models and as line/band spectral irradiances for the physics-based Ionosphere Forecast Model (IFM) developed by the Space Environment Corporation (SEC). We describe the integration of these irradiances in historical, current epoch, and forecast modes through the Communication Alert and Prediction System (CAPS). CAPS provides real-time and forecast HF radio availability for global and regional users and global total electron content (TEC) conditions.

  19. 1/f noise in the UV solar spectral irradiance

    NASA Astrophysics Data System (ADS)

    Varotsos, Costas A.; Melnikova, Irina; Efstathiou, Maria N.; Tzanis, Chris

    2013-02-01

    The investigation of the intrinsic properties of the solar spectral irradiance as a function of the ultraviolet (UV) wavelength is attempted by exploiting rare observations performed at the Villard St. Pancrace station of the Lille University of Sciences and Technology ranging from 278 to 400 nm with a step of 0.05 nm every half an hour from nearly sunrise to sunset. To achieve this goal, the modern method of the detrended fluctuation analysis was applied on the solar spectral irradiance values versus wavelength. This analysis revealed that the solar incident flux at the top of the atmosphere and the solar spectral irradiance at the ground during two overcast sky days fluctuate with the UV wavelength exhibiting persistent long-range power-law behavior. More interestingly, the exponent of the power-law relationship between the fluctuations of the solar spectral irradiance versus UV wavelength at both the top of the atmosphere and the ground is consistently close to unity (of 1/f-type) throughout the day. This 1/f behavior has been detected in many complex dynamical systems, but despite much effort to derive a theory for its widespread occurrence in nature, it remains unexplained so far. According to the above-mentioned findings we speculate that the 1/f property of the incident solar UV flux at the top of the atmosphere could probably drive both the 1/f behavior depicted in the atmospheric components and the solar UV irradiance at the Earth's surface. The latter could influence the UV-sensitive biological ecosystems, giving rise to a 1/f-type variability in the biosphere, which has already been proven by recent observational data. We finally propose that Wien approximation could be multiplied by a 1/f function of wavelength (e.g., of the type of the fractional Brownian motion) in order to reproduce the aforementioned 1/f feature of the solar UV flux.

  20. Radiation pneumonitis following large single dose irradiation: a re-evaluation based on absolute dose to lung

    SciTech Connect

    Van Dyk, J.; Keane, T.J.; Kan, S.; Rider, W.D.; Fryer, C.J.H.

    1981-04-01

    The acute radiation pneumonitis syndrome is a major complication for patients receiving total thoracic irradiation in a large single dose. Previous studies have evaluated the onset of radiation pneumonitis on the basis of radiation doses calculated assuming unit density tissues. In this report, the incidence of radiation pneumonitis is determined as a function of absolute dose to lung. A simple algorithm relating dose correction factor to anterior-posterior patient diameter has been derived using a CT-aided treatment planning system. This algorithm was used to determine, retrospectively, the dose to lung for a group of 303 patients who had been treated with large field irradiation techniques. Of this group, 150 patients had no previous lung disease and had virtually no additional lung irradiation prior or subsequent to their large field treatment. The actuarial incidence of radiation pneumonitis versus dose to lung was evaluated using a simplified probit analysis. The resultant best fit sigmoidal complication curve demonstrates the onset of radiation pneumonitis to occur at about 750 rad with the 5% actuarial incidence occurring at approximately 820 rad. The errors associated with the dose determination procedure as well as the actuarial incidence calculations are considered. The time of onset of radiation pneumonitis occurs between 1 to 7 months after irradiation for 90% of the patients who developed pneumonitis with the peak incidence occurring at 2 at 3 months. No correlation was found between time of onset and the dose to lung over a dose range of 650 to 1250 rad.

  1. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1994-02-01

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with approximately 15-nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy, providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates.

  2. Spectrum line intensity as a surrogate for solar irradiance variations.

    PubMed

    Livingston, W C; Wallace, L; White, O R

    1988-06-24

    Active Cavity Radiometer Irradiance Monitor (ACRIM) solar constant measurements from 1980 to 1986 are compared with ground-based, irradiance spectrophotometry of selected Fraunhofer lines. Both data sets were identically sampled and smoothed with an 85-day running mean, and the ACRIM total solar irradiance (S) values were corrected for sunspot blocking (S(c)). The strength of the mid-photospheric manganese 539.4-nanometer line tracks almost perfectly with ACRIM S(e), Other spectral features formed high in the photosphere and chromosphere also track well. These comparisons independently confirm the variability in the ACRIM S(e), signal, indicate that the source of irradiance is faculae, and indicate that ACRIM S(e), follows the 11-year activity cycle. PMID:17842428

  3. A Compact Solar Spectral Irradiance Monitor for Future Small Satellite and CubeSat Science Opportunities

    NASA Astrophysics Data System (ADS)

    Richard, E. C.; Harber, D.; Snow, M. A.; Harder, J. W.

    2013-12-01

    Accurate and continuous measurements of solar spectral irradiance (SSI) is recognized as being increasingly important to advancing our understanding of the solar influence on Earth's climate. For example, the magnitude of SSI UV variability has significant implications, both directly and indirectly, for the response of the stratosphere and mesosphere, whereas the visible and near infrared SSI variability influences the radiative balance, thermal structure, and dynamics of the lower atmosphere and ocean layers. Recent SSI measurements are providing critical inputs in evaluating and improving present climate models, however they are not yet of sufficient accuracy to stand alone without overlapping records - gaps in the observational record, caused by future mission delays or early failures of existing missions, effectively destroy our ability to link records from different instruments into a continuous, long-term climate quality record. Recent advancements in calibration facilities and techniques make it now possible to improve significantly the accuracy and traceability of future SSI observations and assure quantification of uncertainty as input to increasingly more sophisticated climate models. The goal of the proposed compact SSI monitor is to cover 200-2400 nm with the required SI-traceable accuracy and on-orbit stability to meet the solar input measurement requirements defined in the Earth Science Decadal Survey for establishing benchmark climate records. Building upon our experiences and resources from the Total and Spectral Solar Irradiance Sensor (TSIS) program, the instrument will reduce the cost, size, and characterization and calibration schedule of a solar spectral irradiance monitor with SI-traceable absolute calibration at the 0.2% uncertainty level (k=1) while maintaining 100 ppm relative stability. System level performance characterizations and final end-to-end absolute irradiance calibration will be accomplished with the LASP Spectral Radiometer

  4. Solar-Stellar Irradiance Comparison Experiment 1. II - Instrument calibrations

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Rottman, Gary J.; Ucker, Gregory J.

    1993-01-01

    The science objective for the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) is to accurately measure the full disk solar spectral irradiance in the ultraviolet (UV) spectral region over a long time period. The SOLSTICE design was driven by the requirement for long-term, precise solar photometry conducted from space. The SOLSTICE 1 is on the Upper Atmosphere Research Satellite (UARS), launched in September 1991 with the possibility for a 10-year operational mission. The in-flight calibration for SOLSTICE to meet its primary objective is the routine measurements of the UV radiation from a set of early-type stars, using the identical optical elements employed for the solar observations. The extensive preflight calibrations of the instrument have yielded a precise characterization of the three SOLSTICE channels. Details of the preflight and in-flight SOLSTICE calibrations are discussed in this paper.

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

    NASA Astrophysics Data System (ADS)

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

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

  6. Quality assessment of solar UV irradiance measured with array spectroradiometers

    NASA Astrophysics Data System (ADS)

    Egli, Luca; Gröbner, Julian; Hülsen, Gregor; Bachmann, Luciano; Blumthaler, Mario; Dubard, Jimmy; Khazova, Marina; Kift, Richard; Hoogendijk, Kees; Serrano, Antonio; Smedley, Andrew; Vilaplana, José-Manuel

    2016-04-01

    The reliable quantification of ultraviolet (UV) radiation at the earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers (ASRMs) are small, light, robust and cost-effective instruments, and are increasingly used for spectral irradiance measurements. Within the European EMRP ENV03 project "Solar UV", new devices, guidelines and characterization methods have been developed to improve solar UV measurements with ASRMs, and support to the end user community has been provided. In order to assess the quality of 14 end user ASRMs, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the blind intercomparison revealed that ASRMs, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema-weighted UV index - in particular at large solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available ASRMs within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range of solar zenith angles. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 and 400 nm under all atmospheric conditions.

  7. Quality assessment of solar UV irradiance measured with array spectroradiometers

    NASA Astrophysics Data System (ADS)

    Egli, L.; Gröbner, J.; Hülsen, G.; Bachmann, L.; Blumthaler, M.; Dubard, J.; Khazova, M.; Kift, R.; Hoogendijk, K.; Serrano, A.; Smedley, A. R. D.; Vilaplana, J.-M.

    2015-12-01

    The reliable quantification of ultraviolet (UV) radiation at the Earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers are small, light, robust and cost effective instruments and are increasingly used for spectral irradiance measurements. Within the European EMRP-ENV03 project "Solar UV", new devices, guidelines, and characterization methods have been developed to improve solar UV measurements with array spectroradiometers and support to the end-user community has been provided. In order to assess the quality of 14 end-user array spectroradiometers, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the intercomparison revealed that array spectroradiometers, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema weighted UV index - in particular at low solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available array spectroradiometer within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range or solar zenith angle. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 to 400 nm under all atmospheric conditions.

  8. The solar spectral irradiance 1200-3184 a near solar maximum, 15 July 1980

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Full disk solar spectral irradiances near solar maximum were obtained in the spectral range 1200 to 3184 A at a spectral resolution of approximately 1 A from rocket observations above White Sands Missile Range. Comparison with measurements made during solar minimum confirm a large increase at solar maximum in the solar irradiance near 1200 A with no change within the measurement errors near 2000 A. Irradiances in the range 1900 to 2100 A are in excellent agreement with previous measurements, and those in the 2100 to 2500 A range are lower than separate previous results in this range. Agreement is found with previous values 2500 to 2900 A A, and then fall below those values 2900 to 3184 A.

  9. Lyman alpha solar spectral irradiance line profile observations and models

    NASA Astrophysics Data System (ADS)

    Snow, Martin; Machol, Janet; Quemerais, Eric; Curdt, Werner; Kretschmar, Matthieu; Haberreiter, Margit

    2016-04-01

    Solar lyman alpha solar spectral irradiance measurements are available on a daily basis, but only the 1-nm integrated flux is typically published. The International Space Science Institute (ISSI) in Bern, Switzerland has sponsored a team to make higher spectral resolution data available to the community. Using a combination of SORCE/SOLSTICE and SOHO/SUMER observations plus empirical and semi-empirical modeling, we will produce a dataset of the line profile. Our poster will describe progress towards this goal.

  10. Solar Spectral Irradiance Variability in November/December 2012: Comparison of Observations by Instruments on the International Space Station and Models

    NASA Astrophysics Data System (ADS)

    Thuillier, G.; Schmidtke, G.; Erhardt, C.; Nikutowski, B.; Shapiro, A. I.; Bolduc, C.; Lean, J.; Krivova, N.; Charbonneau, P.; Cessateur, G.; Haberreiter, M.; Melo, S.; Delouille, V.; Mampaey, B.; Yeo, K. L.; Schmutz, W.

    2014-12-01

    Onboard the International Space Station (ISS), two instruments are observing the solar spectral irradiance (SSI) at wavelengths from 16 to 2900 nm. Although the ISS platform orientation generally precludes pointing at the Sun more than 10 - 14 days per month, in November/December 2012 a continuous period of measurements was obtained by implementing an ISS `bridging' maneuver. This enabled observations to be made of the solar spectral irradiance (SSI) during a complete solar rotation. We present these measurements, which quantify the impact of active regions on SSI, and compare them with data simultaneously gathered from other platforms, and with models of spectral irradiance variability. Our analysis demonstrates that the instruments onboard the ISS have the capability to measure SSI variations consistent with other instruments in space. A comparison among all available SSI measurements during November-December 2012 in absolute units with reconstructions using solar proxies and observed solar activity features is presented and discussed in terms of accuracy.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  12. Evolution of the solar irradiance during the Holocene

    NASA Astrophysics Data System (ADS)

    Vieira, L. E. A.; Solanki, S. K.; Krivova, N. A.; Usoskin, I.

    2011-07-01

    Context. Long-term records of solar radiative output are vital for understanding solar variability and past climate change. Measurements of solar irradiance are available for only the last three decades, which calls for reconstructions of this quantity over longer time scales using suitable models. Aims: We present a physically consistent reconstruction of the total solar irradiance for the Holocene. Methods: We extend the SATIRE (Spectral And Total Irradiance REconstruction) models to estimate the evolution of the total (and partly spectral) solar irradiance over the Holocene. The basic assumption is that the variations of the solar irradiance are due to the evolution of the dark and bright magnetic features on the solar surface. The evolution of the decadally averaged magnetic flux is computed from decadal values of cosmogenic isotope concentrations recorded in natural archives employing a series of physics-based models connecting the processes from the modulation of the cosmic ray flux in the heliosphere to their record in natural archives. We then compute the total solar irradiance (TSI) as a linear combination of the jth and jth + 1 decadal values of the open magnetic flux. In order to evaluate the uncertainties due to the evolution of the Earth's magnetic dipole moment, we employ four reconstructions of the open flux which are based on conceptually different paleomagnetic models. Results: Reconstructions of the TSI over the Holocene, each valid for a different paleomagnetic time series, are presented. Our analysis suggests that major sources of uncertainty in the TSI in this model are the heritage of the uncertainty of the TSI since 1610 reconstructed from sunspot data and the uncertainty of the evolution of the Earth's magnetic dipole moment. The analysis of the distribution functions of the reconstructed irradiance for the last 3000 years, which is the period that the reconstructions overlap, indicates that the estimates based on the virtual axial dipole

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  15. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  16. Rocket measurements of the solar spectral irradiance during solar minimum, 1972-1977

    NASA Technical Reports Server (NTRS)

    Rottman, G. J.

    1981-01-01

    Five sounding rocket experiments conducted between December 1972 and March 1977, a period spanning solar minimum between cycles 20 and 21, provide full disc solar irradiance data in the spectral range 120-190 nm. The five measurements have been combined to give a solar minimum reference table. This spectrum is compared with other measurements obtained during the same time period. A table of intensities for the strong emission lines at wavelengths between 120 and 190 nm is presented.

  17. 1978-1988 Total Solar Irradiance (TSI) Variability Trends

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Priestley, Kory J.; Wilson, Robert S.; Al-Hajjah, Aiman; Paden, Jack; Pandey, Dhirendra K.; Thomas, Susan

    1999-01-01

    Total solar irradiance (TSI), normalized to the mean earth-sun distance, is analyzed to assess long-term solar variability which may affect climate. TSI data sets are reviewed primarily from the 1984-1999 Earth Radiation Budgets Satellite (ERBS), 1978-1993 Nimbus7, 1980-1989 Solar Maximum Mission (SMM), 19911998 Upper Atmospheric Research Satellite (UARS), and 1996-1998 Solar and Heliospheric Observatory (SOHO)/ Variability of solar IRradiance and Gravity Oscillations (VIRGO) Spacecraft missions. The data sets indicate that 1365 W/sq m [Watts per meter square] is the most likely TSI amplitude at minimum solar magnetic activity as indicated by minimum sunspot numbers. The TSI long-term variability component was found to vary with a period of approximately 10 years and with an amplitude of 2 W/sq m. An empirical TSI fit model, based upon 10.7-cm solar radio fluxes and prompt photometric sunspot indices, was used to characterize TSI variability. Comparisons among TSI measurements and empirical fit trends are reviewed as well as inconsistencies among current spacecraft TSI data set trends. The 1996-1998, SOHO/VIRGO measurement indicate stronger TSI increasing trends than those suggested by the corresponding ERBS and UARS measurement and by the empirical model fit. 1978-1999 TSI data sets are analyzed to identify the probable existence of another long-term TSI variability component.

  18. SORCE and Future Satellite Observations of Solar Irradiance

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Rottman, G.; Woods, T.; Lawrence, G.; Kopp, G.; Harder, J.; McClintock, W.

    2003-01-01

    With solar activity just passing the maximum of cycle 23, SORCE is beginning a 5 year mission to measure total solar irradiance (TSI) with unprecedented accuracy using phase-sensitive detection, and to measure spectral solar irradiance (SSI) with unprecedented spectral coverage, from 1 to 2000 nm. The new Total Irradiance Monitor (TIM) has 4 active cavity radiometers, any one of which can be used as a fixed-temperature reference against any other that is exposed to the Sun via a shutter that cycles at a rate designed to minimize noise at the shutter frequency. The new Spectral Irradiance Monitor (SIM) is a dual Fery prism spectrometer that can employ either prism as a monochromatic source on the other prism, thus monitoring its transmission during the mission lifetime. Either prism can measure SSI from 200 to 2000 nm, employing the same phase-sensitive electrical substitution strategy as TIM. SORCE also carries dual SOLSTICE instruments to cover the spectral range 100-320 nm, similar to the instruments onboard UARS, and also an XUV Photometer System (XPS) similar to that on TIMED. SSI has now been added to TSI as a requirement of EOS and NPOESS, because different spectral components drive different components of the climate system - UV into upper atmosphere and stratospheric ozone, IR into tropospheric water vapor and clouds, and Visible into the oceans and biosphere. Succeeding satellite missions being planned for 2006 and 2011 will continue to monitor these critical solar variables.

  19. Models of Solar Irradiance Variability and the Instrumental Temperature Record

    NASA Technical Reports Server (NTRS)

    Marcus, S. L.; Ghil, M.; Ide, K.

    1998-01-01

    The effects of decade-to-century (Dec-Cen) variations in total solar irradiance (TSI) on global mean surface temperature Ts during the pre-Pinatubo instrumental era (1854-1991) are studied by using two different proxies for TSI and a simplified version of the IPCC climate model.

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

    SciTech Connect

    Adeyefa, Z.D.; Holmgren, B.

    1996-09-01

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

  1. Modeling monthly mean variation of the solar global irradiation

    NASA Astrophysics Data System (ADS)

    Vindel, J. M.; Polo, J.; Zarzalejo, L. F.

    2015-01-01

    The monthly mean variation of the solar global reaching the Earth's surface has been characterized at a global level by a regression model. This model considers the monthly variation itself (to different horizons and even the maximum annual variation) as the study variable, and it is applied without using data corresponding to measured meteorological variable. Two explicative variables have been used, the variation of the extraterrestrial irradiation and the variation of the clear sky global horizontal irradiation. The work has been carried out from datasets including average global daily solar irradiation for each month of the year measured on the ground. The model quality has been proven to be very dependent of the temporal variation considered, in such a way that higher variations, that is to say, higher distances between months, lead to an improvement in the model outcomes.

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

    PubMed

    Schuster, Michaela; Nevas, Saulius; Sperling, Armin

    2014-05-01

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

  3. Annealing characteristics of irradiated hydrogenated amorphous silicon solar cells

    NASA Technical Reports Server (NTRS)

    Payson, J. S.; Abdulaziz, S.; Li, Y.; Woodyard, J. R.

    1991-01-01

    It was shown that 1 MeV proton irradiation with fluences of 1.25E14 and 1.25E15/sq cm reduces the normalized I(sub SC) of a-Si:H solar cell. Solar cells recently fabricated showed superior radiation tolerance compared with cells fabricated four years ago; the improvement is probably due to the fact that the new cells are thinner and fabricated from improved materials. Room temperature annealing was observed for the first time in both new and old cells. New cells anneal at a faster rate than old cells for the same fluence. From the annealing work it is apparent that there are at least two types of defects and/or annealing mechanisms. One cell had improved I-V characteristics following irradiation as compared to the virgin cell. The work shows that the photothermal deflection spectroscopy (PDS) and annealing measurements may be used to predict the qualitative behavior of a-Si:H solar cells. It was anticipated that the modeling work will quantitatively link thin film measurements with solar cell properties. Quantitative predictions of the operation of a-Si:H solar cells in a space environment will require a knowledge of the defect creation mechanisms, defect structures, role of defects on degradation, and defect passivation and annealing mechanisms. The engineering data and knowledge base for justifying space flight testing of a-Si:H alloy based solar cells is being developed.

  4. Distinct EUV minimum of the solar irradiance (16-40 nm) observed by SolACES spectrometers onboard the International Space Station (ISS) in August/September 2009

    NASA Astrophysics Data System (ADS)

    Nikutowski, B.; Brunner, R.; Erhardt, Ch.; Knecht, St.; Schmidtke, G.

    2011-09-01

    In the field of terrestrial climatology the continuous monitoring of the solar irradiance with highest possible accuracy is an important goal. SolACES as a part of the ESA mission SOLAR on the ISS is measuring the short-wavelength solar EUV irradiance from 16-150 nm. This data will be made available to the scientific community to investigate the impact of the solar irradiance variability on the Earth's climate as well as the thermospheric/ionospheric interactions that are pursued in the TIGER program. Since the successful launch with the shuttle mission STS-122 on February 7th, 2008, SolACES initially recorded the low EUV irradiance during the extended solar activity minimum. Thereafter it has been observing the EUV irradiance during the increasing solar activity with enhanced intensity and changing spectral composition. SolACES consists of three grazing incidence planar grating spectrometers. In addition there are two three-signal ionisation chambers, each with exchangeable band-pass filters to determine the absolute EUV fluxes repeatedly during the mission. One important problem of space-borne instrumentation recording the solar EUV irradiance is the degradation of the spectrometer sensitivity. The two double ionisation chambers of SolACES, which could be re-filled with three different gases for each recording, allow the recalibration of the efficiencies of the three SolACES spectrometers from time to time.

  5. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  6. Granulation, Irradiance and Diameter Solar Variations

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Reis Neto, Eugenio

    2015-08-01

    Though granulation forms the very face of sun’s photosphere, there are no long term registers of it. Observational and computational hardships to define and follow such highly variable “face” have so far prevented the realization of those registers. However, in recent years a large, coherent body of white light images became available. We retrieved white light, full solar disk images from the BBSO, to a total of 1104 treated ones and 1245 treated and compensated for limb darkening ones. The time coverage extends from the year 2000 to 2005, thus covering the rise and fall of the solar cycle 23. For the analysis, only the central 0.35R portion of the Sun was considered. The central portion was then divided into 100 subsectors, to average and discard the deviant results. The analysis goal is to derive the long term behavior of the photosphere granulation, in broad statistical sense. Three statistics were this way calculated: the standard deviation of the counts (that answers to the grains size); the counts difference between the maximum and minimum tenths (that answers to the grains brightness); the degree of the best fit polynomial along lines and columns (that answers to the grains numbers). According to the statistics, there is no significant variation in the number of grains. The grains sizes are the largest by the solar maximum, in excellent agreement with the maximum of the measured diameter. The grains brightness, on the contrary, is minimum at the solar maximum, and again an excellent agreement is verified with the maximum of the measured diameter.

  7. Evaluation of the Delta-T SPN1 radiometer for the measurement of solar irradiance components

    NASA Astrophysics Data System (ADS)

    Estelles, Victor; Serrano, David; Segura, Sara; Wood, John; Webb, Nick; Utrillas, Maria Pilar

    2016-04-01

    In this study we analyse the performance of an SPN1 radiometer built by Delta-T Devices Ltd. to retrieve global solar irradiance at ground and its components (diffuse, direct) in comparison with measurements from two Kipp&Zonen CMP21 radiometers and a Kipp&Zonen CHP1 pirheliometer, mounted on an active Solys-2 suntracker at the Burjassot site (Valencia, Spain) using data acquired every minute during years 2013 - 2015. The measurement site is close to sea level (60 m a.s.l.), near the Mediterranean coast (10 km) and within the metropolitan area of Valencia City (over 1.500.000 inhabitants). The SPN1 is an inexpensive and versatile instrument for the measurement of the three components of the solar radiation without any mobile part and without any need to azimuthally align the instrument to track the sun (http://www.delta-t.co.uk). The three components of the solar radiation are estimated from a combination of measurements performed by 7 different miniature thermopiles. The SPN1 pyranometer measures the irradiance between 400 and 2700 nm, and the nominal uncertainty for the individual readings is about 8% ± 10 W/m2 (5% for the daily averages). The pyranometer Kipp&Zonen CMP21 model is a secondary standard for the measurement of broadband solar global irradiance in horizontal planes. Two ventilated CMP21 are used for the measurement of the global and diffuse irradiances. The expected total daily uncertainty of the radiometer is estimated to be 2%. The pirheliometer Kipp&Zonen CHP1 is designed for the measurement of the direct irradiance. The principles are similar to the CMP21 pyranometer. The results of the comparison show that the global irradiance from the SPN1 compares very well with the CMP21, with absolute RMSD and MBD differences below the combined uncertainties (15 W/m2 and -5.4 W/m2, respectively; relative RMSD of 3.1%). Both datasets are very well correlated, with a correlation coefficient higher than 0.997 and a slope and intercept very close to 1 and 0

  8. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-08-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  9. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-01-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  10. Irradiance optimization of outdoor microalgal cultures using solar tracked photobioreactors.

    PubMed

    Hindersin, Stefan; Leupold, Marco; Kerner, Martin; Hanelt, Dieter

    2013-03-01

    Photosynthetic activity and temperature regulation of microalgal cultures (Chlorella vulgaris and Scenedesmus obliquus) under different irradiances controlled by a solar tracker and different cell densities were studied in outdoor flat panel photobioreactors. An automated process control unit regulated light and temperature as well as pH value and nutrient concentration in the culture medium. CO2 was supplied using flue gas from an attached combined block heat and power station. Photosynthetic activity was determined by pulse amplitude modulation fluorometry. Compared to the horizontal irradiance of 55 mol photons m(-2) d(-1) on a clear day, the solar tracked photobioreactors enabled a decrease and increase in the overall light absorption from 19 mol photons m(-2) d(-1) (by rotation out of direct irradiance) to 79 mol photons m(-2) d(-1) (following the position of the sun). At biomass concentrations below 1.1 g cell dry weight (CDW) L(-1), photoinhibition of about 35 % occurred at irradiances of ≥1,000 μmol photons m(-2) s(-1) photosynthetic active radiation (PAR). Using solar tracked photobioreactors, photoinhibition can be reduced and at optimum biomass concentration (≥2.3 g CDW L(-1)), the culture was irradiated up to 2,000 μmol photons m(-2) s(-1) to overcome light limitation with biomass yields of 0.7 g CDW mol photons(-1) and high photosynthetic activities indicated by an effective quantum yield of 0.68 and a maximum quantum yield of 0.80 (F v/F m). Overheating due to high irradiance was avoided by turning the PBR out of the sun or using a cooling system, which maintained the temperature close to the species-specific temperature optima. PMID:22847362

  11. The Missing Solar Irradiance Spectrum: 1 to 7 nm

    NASA Astrophysics Data System (ADS)

    Sojka, J. J.; Lewis, M.; David, M.; Schunk, R. W.; Woods, T. N.; Eparvier, F. G.; Warren, H. P.

    2015-12-01

    During large X-class flares the Earth's upper atmospheric E-region responds immediately to solar photons in the 1 to 7 nm range. The response can change the E-region density by factors approaching 10, create large changes in conductivity, and plague HF communications. GOES-XRS provide 0.1 to 0.8 nm and a 0.05 to 0.4 nm integral channels; SOHO-SEM provided a 0 to 50 nm irradiance; TIMED and SORCE-XPS diode measurements also integrated down to 0.1 nm; and most recently SDO-EVE provided a 0.1 to 7 nm irradiance. For atmospheric response to solar flares the cadence is also crucial. Both GOES and SDO provided integral measurements at 10 seconds or better. Unfortunately these measurements have failed to capture the 1 to 7 nm spectral changes that occur during flares. It is these spectral changes that create the major impact since the ionization cross-section of the dominant atmospheric species, N2 and O2, both contain step function changes in the cross-sections. Models of the solar irradiance over this critical wavelength regime have suffered from the need to model the spectral variability based on incomplete measurements. The most sophisticated empirical model FISM [Chamberlin et al., 2008] used 1 nm spectral binning and various implementations of the above integral measurements to describe the 1 to 7 nm irradiance. Since excellent solar observations exist at other wavelengths it is possible to construct an empirical model of the solar atmosphere and then use this model to infer the spectral distribution at wavelengths below 5 nm. This differential emission measure approach has been used successfully in other contexts [e.g., Warren, 2005, Chamberlin et al., 2009]. This paper contrasts the broadband versus spectrally resolved descriptions of the incoming irradiance that affects the upper atmospheric E-layer. The results provide a prescription of what wavelength resolution would be needed to adequately measure the incoming solar irradiance in the 1 to 7 nm range.

  12. Photometric measurements of solar irradiance variations due to sunspots

    NASA Technical Reports Server (NTRS)

    Chapman, G. A.; Herzog, A. D.; Laico, D. E.; Lawrence, J. K.; Templer, M. S.

    1989-01-01

    A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage.

  13. Photometric measurements of solar irradiance variations due to sunspots

    SciTech Connect

    Chapman, G.A.; Herzog, A.D.; Laico, D.E.; Lawrence, J.K.; Templer, M.S. )

    1989-08-01

    A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage. 23 refs.

  14. Effect of solar irradiation on extracellular enzymes of Aeromonas proteolytica

    NASA Technical Reports Server (NTRS)

    Foster, B. G.

    1973-01-01

    The bacterium Aeromonas proteolytica was selected for studying the effects of solar irradiation on extracellular enzymes because it produces an endopeptidase that is capable of degrading proteins and a hemolysin that is active in lysing human erythrocytes. Possible alterations in the rate of enzyme production in response to the test conditions are currently underway and are not available for this preliminary report. Completed viability studies are indicative that little difference exists among the survival curves derived for cells exposed to various components of ultraviolet irradiation in space.

  15. Electron irradiation effects in epitaxial InP solar cells

    NASA Technical Reports Server (NTRS)

    Pearsall, N. M.; Robson, N.; Sambell, A. J.; Anspaugh, B.; Cross, T. A.

    1991-01-01

    Performance data for InP-based solar cells after irradiation with 1-MeV electrons up to a fluence of 1 x 1016 e/cm2 are presented. Three InP cell structures are considered. Two of these have epitaxially grown active regions, these being a homojunction design and in ITO/InP structure. These are compared with ITO/InP cells without the epitaxial base region. The cell parameter variations, the influence of illumination during irradiation, and the effect on cell spectral response and capacitance measurements are discussed. Substantial performance recovery after thermal annealing at 90 C is reported.

  16. Properties of solar gravity mode signals in total irradiance observations

    SciTech Connect

    Kroll, R.J.; Chen, J.; Hill, H.A.

    1988-01-01

    Further evidence has been found that a significant fraction of the gravity mode power density in the total irradiance observations appears in sidebands of classified eigenfrequencies. These sidebands whose amplitudes vary from year to year are interpreted as harmonics of the rotational frequencies of the nonuniform solar surface. These findings are for non axisymmetric modes and corroborate the findings of Kroll, Hill and Chen for axisymmetric modes. It is demonstrated the the generation of the sidebands lifts the usual restriction on the parity of the eigenfunctions for modes detectable in total irradiance observations. 14 refs.

  17. What Causes the Inter-solar-cycle Variation of Total Solar Irradiance?

    NASA Astrophysics Data System (ADS)

    Xiang, N. B.; Kong, D. F.

    2015-12-01

    The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statistical significance test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.

  18. Method to Calculate Uncertainty Estimate of Measuring Shortwave Solar Irradiance using Thermopile and Semiconductor Solar Radiometers

    SciTech Connect

    Reda, I.

    2011-07-01

    The uncertainty of measuring solar irradiance is fundamentally important for solar energy and atmospheric science applications. Without an uncertainty statement, the quality of a result, model, or testing method cannot be quantified, the chain of traceability is broken, and confidence cannot be maintained in the measurement. Measurement results are incomplete and meaningless without a statement of the estimated uncertainty with traceability to the International System of Units (SI) or to another internationally recognized standard. This report explains how to use International Guidelines of Uncertainty in Measurement (GUM) to calculate such uncertainty. The report also shows that without appropriate corrections to solar measuring instruments (solar radiometers), the uncertainty of measuring shortwave solar irradiance can exceed 4% using present state-of-the-art pyranometers and 2.7% using present state-of-the-art pyrheliometers. Finally, the report demonstrates that by applying the appropriate corrections, uncertainties may be reduced by at least 50%. The uncertainties, with or without the appropriate corrections might not be compatible with the needs of solar energy and atmospheric science applications; yet, this report may shed some light on the sources of uncertainties and the means to reduce overall uncertainty in measuring solar irradiance.

  19. An Improved Total Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

    Kopp, G.

    2011-12-01

    The dominant driver of the Earth's climate system is the Sun, which exceeds all other energy sources combined by a factor of 2500. Small as they are, variations in the enormous amount of energy received from the Sun can have climatic effects on the Earth over annual to millennial time scales. Climate studies rely on recent spaceborne measurements of total solar irradiance (TSI) and estimates of its historical variability to discern natural from anthropogenic climatic influences. Because the Sun is relatively stable, the TSI measurements providing this solar record must be of high accuracy, extremely good stability, and long duration. New instrument calibrations and diagnostics have improved the accuracy of the existing record and future instruments promise further improvements. I will discuss the status of the current solar climate data record based on recent findings, explain the climate-driven solar irradiance measurement requirements, show estimates of solar influences on climate, and give an overview of planned missions to provide this needed record for climate studies.

  20. Some Impacts of Solar Irradiance Variation on Terrestrial Climate

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    As chairman of the Special Session addressing the above topic, a brief overview of the problem will be offered, after which 20-minute talks will be given on the determination of solar irradiance variations from space observations (Dr. Judit Pap) and from groundbased measurements of solar magnetic fields (Dr. Harrison Jones). The chairman will then introduce four panel members representing different areas of expertise bearing on the topic. Each panel member will offer a brief 5-minute summary of his views. Panel members are: Chick Keller, Los Alamos National Laboratory; Drew Shindell, Goddard Institute for Space Science, Columbia University; Michael Schlesinger, University of Illinois; Sabatino Sofia, Yale University. General Circulation Models of the terrestrial atmosphere, the possible impact on this atmosphere of large percentage changes in the solar EUV over a solar cycle, and the role of strong magnetic field in the solar convection zone on irradiance variation will all be considered in brief summaries. The chairman will conclude the session by facilitating a discussion between the audience, the main speakers, and the panel members.

  1. The Belgian DIARAD Total Solar Irradiance Observations, Historical Objectives, Achievements and Particularities.

    NASA Astrophysics Data System (ADS)

    Crommelynck, D.

    2007-12-01

    The origin of the Total Solar Irradiance (TSI) observations at the Royal Meteorological Institute of Belgium is the will to monitor the Earth Radiation Budget (ERB) whereoff the TSI is one of the terms, the two others are the reflected solar radiation and the Earth emitted radiation actually measured operationnaly by the Geostationnary Earth Radiation Budget (GERB) experiment on board of EUMETSAT MSG. This concerns atmospheric physics as well as climate. The new design of a differential absolute radiometer (DIARAD) characterised in air as well as in vacuum, led to its incorporation in the set of instruments defining the World Radiometric Reference (WRR); adapted for space, it flew repetitively on the space shuttle as well as on the european retrievable carrier (EURECA). Since 1996 DIARAD operates contineously without any failure from VIRGO on SOHO. Our strategic principles required to insure a long range high quality TSI data base are developed . It incorporates the usage of Space Absolute Radiometric Reference (SARR) coefficients to normalise the observations in time. The compared characteristics of DIARAD and PMO instruments are presented as well as the chronological events and behaviours of the radiometers flying on VIRGO/SOHO. It is concluded that a minimum of three simultaneous flying radiometers are required to guarantee the value of the TSI data base.

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

    NASA Technical Reports Server (NTRS)

    Platnick, Steven; Fontenla, Juan M.

    2006-01-01

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

  3. Accessing Solar Irradiance Data via LISIRD, the Laboratory for Atmospheric and Space Physics Interactive Solar Irradiance Datacenter

    NASA Astrophysics Data System (ADS)

    Pankratz, C. K.; Wilson, A.; Snow, M. A.; Lindholm, D. M.; Woods, T. N.; Traver, T.; Woodraska, D.

    2015-12-01

    The LASP Interactive Solar Irradiance Datacenter, LISIRD, http://lasp.colorado.edu/lisird, allows the science community and the public to explore and access solar irradiance and related data sets using convenient, interactive or scriptable, standards-based interfaces. LISIRD's interactive plotting allows users to investigate and download irradiance data sets from a variety of sources, including space missions, ground observatories, and modeling efforts. LISIRD's programmatic interfaces allow software-level data retrievals and facilitate automation. This presentation will describe the current state of LISIRD, provide details of the data sets it serves, outline data access methods, identify key technologies in-use, and address other related aspects of serving spectral and other time series data. We continue to improve LISIRD by integrating new data sets, and also by advancing its data management and presentation capabilities to meet evolving best practices and community needs. LISIRD is hosted and operated by the Laboratory for Atmospheric and Space Physics, LASP, which has been a leader in Atmospheric and Heliophysics science for over 60 years. LASP makes a variety of space-based measurements of solar irradiance, which provide crucial input for research and modeling in solar-terrestrial interactions, space physics, planetary, atmospheric, and climate sciences. These data sets consist of fundamental measurements, composite data sets, solar indices, space weather products, and models. Current data sets available through LISIRD originate from the SORCE, SDO (EVE), UARS (SOLSTICE), TIMED (SEE), and SME space missions, as well as several other space and ground-based projects. LISIRD leverages several technologies to provide flexible and standards-based access to the data holdings available through LISIRD. This includes internet-accessible interfaces that permit data access in a variety of formats, data subsetting, as well as program-level access from data analysis

  4. Influence of solar UVA on erythemal irradiances.

    PubMed

    Parisi, A V; Turnbull, D J; Kimlin, M G

    2006-06-21

    Many materials in everyday use such as window glass in homes and offices, glass in sunrooms and greenhouses, vehicle glass and some brands of sunscreens act as a barrier to the shorter UVB wavelengths while transmitting some of the longer UVA wavelengths. This paper reports on the erythemal exposures due to the UVA waveband encountered over a 12-month period for a solar zenith angle (SZA) range of 4 degrees to 80 degrees and the resulting times required for an erythemal exposure of one standard erythemal dose (SED) due to the erythemal exposures to the UVA wavelengths. The minimum time for an exposure of one SED due to the UVA wavelengths in winter is approximately double that what it is in summer. The time period of 40 to 60 min was the most frequent length of time for an exposure of one SED with 60 to 80 min the next frequent length of time required for a one SED exposure. PMID:16757874

  5. Temperature dependence of damage coefficient in electron irradiated solar cells

    NASA Technical Reports Server (NTRS)

    Faith, T. J.

    1973-01-01

    Measurements of light-generated current vs cell temperature on electron-irradiated n/p silicon solar cells show the temperature coefficient of this current to increase with increasing fluence for both 10-ohm and 20-ohm cells. A relationship between minority-carrier diffusion length and light-generated current was derived by combining measurements of these two parameters: vs fluence at room temperature, and vs cell temperature in cells irradiated to a fluence of 1 x 10 to the 15th power e/sq cm. This relationship was used, together with the light-generated current data, to calculate the temperature dependence of the diffusion-length damage coefficient. The results show a strong decrease in the damage coefficient with increasing temperature in the range experienced by solar panels in synchronous earth orbit.

  6. The incident solar irradiance at the sea surface

    NASA Technical Reports Server (NTRS)

    Van Tran, AN; Collins, Donald J.

    1990-01-01

    Computations have been performed of the incident spectral irradiance at the sea surface using LOWTRAN-7 as the basis to describe the incident scalar and vector irradiance in terms of the true solar zenith angle and the nominal visibility in the atmosphere. These computations have been used to describe the contributions to the incident irradiance from the direct and the sky components of the total irradiance and the average cosine of the sky component as a measure of the radiance distribution of the sky for varying atmospheric conditions. Comparisons of the computations from LOWTRAN-7 have been made with the results from other models, and with data obtained from field measurements, and excellent agreement has been obtained for the daily profiles of the vector and scalar irradiance at the surface. These computations have been used to provide a description of the irradiance at the sea surface for use in the analysis of remotely sensed data based on information on the radiative transfer through the atmosphere above the sea surface.

  7. Measurements and modeling of total solar irradiance in X-class solar flares

    SciTech Connect

    Moore, Christopher Samuel; Chamberlin, Phillip Clyde; Hock, Rachel

    2014-05-20

    The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.

  8. Measurements and Modeling of Total Solar Irradiance in X-class Solar Flares

    NASA Technical Reports Server (NTRS)

    Moore, Christopher S.; Chamberlin, Phillip Clyde; Hock, Rachel

    2014-01-01

    The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.

  9. Fuzzy Sets Theory Applied for Computing Global Solar Irradiation

    NASA Astrophysics Data System (ADS)

    St. Boata, R.; Paulescu, M.; Tulcan-Paulescu, E.; Gravila, P.

    2011-10-01

    A new model to estimate daily global solar irradiation via air temperature data developed inside Takagi-Sugeno fuzzy approach is reported. A critical assessment of the model performance and limitations is conducted, overall results demonstrating a reasonable level of accuracy. The model uses as input only the daily air temperature extremes, worldwide the most available meteorological parameters, which greatly increases its area of application.

  10. Variability in solar irradiance observed at two contrasting Antarctic sites

    NASA Astrophysics Data System (ADS)

    Petkov, Boyan H.; Láska, Kamil; Vitale, Vito; Lanconelli, Christian; Lupi, Angelo; Mazzola, Mauro; Budíková, Marie

    2016-05-01

    The features of erythemally weighted (EW) and short-wave downwelling (SWD) solar irradiances, observed during the spring-summer months of 2007-2011 at Johann Gregor Mendel (63°48‧S, 57°53‧W, 7 m a.s.l.) and Dome Concordia (75°06‧S, 123°21‧E, 3233 m a.s.l.) stations, placed at the Antarctic coastal region and on the interior plateau respectively, have been analysed and compared to each other. The EW and SWD spectral components have been presented by the corresponding daily integrated values and were examined taking into account the different geographic positions and different environmental conditions at both sites. The results indicate that at Mendel station the surface solar irradiance is strongly affected by the changes in the cloud cover, aerosols and albedo that cause a decrease in EW between 20% and 35%, and from 0% to 50% in SWD component, which contributions are slightly lower than the seasonal SWD variations evaluated to be about 71%. On the contrary, the changes in the cloud cover features at Concordia station produce only a 5% reduction of the solar irradiance, whilst the seasonal oscillations of 94% turn out to be the predominant mode. The present analysis leads to the conclusion that the variations in the ozone column cause an average decrease of about 46% in EW irradiance with respect to the value found in the case of minimum ozone content at each of the stations. In addition, the ratio between EW and SWD spectral components can be used to achieve a realistic assessment of the radiation amplification factor that quantifies the relationship between the atmospheric ozone and the surface UV irradiance.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  12. Spatial and temporal variability of global surface solar irradiance

    NASA Technical Reports Server (NTRS)

    Bishop, James K. B.; Rossow, William B.

    1991-01-01

    Consideration is given to a fast scheme for computing surface solar irradiance using data from the International Satellite Cloud Climatology Project (ISCCP). Daily mean solar irradiances from the fast scheme reproduce the detailed global results from full radiative transfer model calculations to within 6 and 10 W/sq m over the ocean and land, respectively. Comparison of calculated monthly mean results using 5 m of ISCCP data (July 1983-July 1984) with climatology from the 1970s at six temperature-latitude ocean weather stations shows agreement within published estimates of interannual variability of monthly means at the individual stations. A further test against a 17-day time series at a continental site, where ground and satellite data were spatially and temporally coincident, showed an accuracy of better than 9 W/sq m on a daily basis and less than 4 percent bias in the 17-day mean. Frequently used bulk formulas for solar irradiance are also evaluated in each of these tests.

  13. Real Solar Irradiance Data for Planetary Surface Studies

    NASA Astrophysics Data System (ADS)

    Kramer, G.; Harder, J.; McCord, T.

    2008-12-01

    The precise determination of the solar irradiance (or extraterrestrial spectrum - ETS) is of primary importance for converting space-borne remote sensing radiance data to accurate reflectance values necessary for geological interpretations of planetary surfaces. Historically, the ETS has been determined from either calculating an emitted spectrum based on the Sun's composition, or modeling and removing atmospheric interferences on a solar spectrum obtained by telescopic observations, aircraft, and/or ground measurements. However, modeling an atmosphere is incredibly complex. A solar spectrum thus measured is replete with absorptions caused by molecular vibrations of atmospheric gases and scattering by particulates at wavelengths that would otherwise be diagnostic of petrological or atmospherical properties. An ETS calculated from these measurements must make some general assumptions about atmospheric conditions at the time of acquisition in order to compensate for their effects. However, variations in local pressures, humidity, and particulate compositions present a many-bodied problem that preclude a truly accurate model. Nevertheless, these model spectra are the basis for the ETS used for atmospheric and planetary surface studies. The Spectral Irradiance Monitor (SIM) onboard the Solar Radiation and Climate Experiment (SORCE) provides a better alternative to theoretically-derived ETS by directly measuring the solar irradiance, outside the Earth's atmosphere. For almost six years, SIM has been taking daily measurements of the ETS at wavelengths between 200 and 2400 nm. This spectral range covers most absorption bands diagnostic of mafic mineralogy, thus making SIM's data ideal for terrestrial planetary mapping. Furthermore, SIM's daily measurements allow for enhanced meteorologic studies of other planetary atmospheres. SIM's spectral resolution and signal to noise ratio meet or exceed the sensitivity of current spectrometer detectors.

  14. Solar Irradiance Models and Measurements: A Comparison in the 220-240 nm wavelength band

    NASA Astrophysics Data System (ADS)

    Unruh, Yvonne C.; Ball, Will T.; Krivova, Natalie A.

    2012-07-01

    Solar irradiance models that assume solar irradiance variations to be due to changes in the solar surface magnetic flux have been successfully used to reconstruct total solar irradiance on rotational as well as cyclical and secular time scales. Modelling spectral solar irradiance is not yet as advanced, and also suffers from a lack of comparison data, in particular on solar cycle time scales. Here, we compare solar irradiance in the 220-240 nm band as modelled with SATIRE-S and measured by different instruments on the UARS and SORCE satellites. We find good agreement between the model and measurements on rotational time scales. The long-term trends, however, show significant differences. Both SORCE instruments, in particular, show a much steeper gradient over the decaying part of cycle 23 than the modelled irradiance or that measured by UARS/SUSIM.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  16. Optical reflectance of pyrheliometer absorption cavities: progress toward SI-traceable measurements of solar irradiance.

    PubMed

    Patrick, Heather J; Germer, Thomas A; Zarobila, Clarence J; Cooksey, Catherine C; Yoon, Howard W

    2016-08-10

    We have accurately determined the absorptance of three pyrheliometer cavities at 532 nm by measuring the residual reflectance using an angle-resolved bidirectional reflectometer. Measurements were performed at a normal incidence as a function of the viewing angle and position on the cavity cone. By numerically integrating the measured angle-resolved scatter over both the direction and position and accounting for an obstructed view of the cavity, we determined that the effective cavity reflectance was between 8×10-4 and 9×10-4. Thus, the absorptance of the three cavities ranged from 0.99909±0.00014 to 0.99922±0.00012 (k=2 combined expanded uncertainties). These measurements, when extended over the spectral range of operation of the pyrheliometer, are required to establish SI traceability for absolute solar irradiance measurements. PMID:27534478

  17. Satellite Observations of Solar Irradiance and Sun-Climate Impacts

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    Solar activity is now near its maximum, with events such as the 2001 "Bastille Day Event", a Coronal Mass Ejection which merited a full session at AGUs annual meeting - and two major sunspot groupings earlier this year, with associated variations in TSI (Total Solar Irradiance). We discuss recent satellite measurements of TSI by ACRIM 2 and 3 and Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) expected from the SORCE mission, planned to launch in fall 2002. SSI has been added to TSI as a required EOS and NPOESS measurement because different spectral components provide energy inputs to different components of the climate system - UV into upper atmosphere and ozone, IR into lower atmosphere and clouds, and Visible into the biosphere. Succeeding satellite missions being planned for 2006 and 2010 will continue to monitor both TSI and SSI. We summarize current ideas about the potential impact of solar variability on Earth's climate on time scales from days to decades to centuries.

  18. Satellite Observations of Solar Irradiance and Sun-Climate Impacts

    NASA Technical Reports Server (NTRS)

    Cahalan, R.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Solar activity is now near its maximum, with events such as the 2001 "Bastille Day Event", a Coronal Mass Ejection which merited a full session at AGO'S annual meeting - and two major sunspot groupings earlier this year, with associated variations in TSI (Total Solar Irradiance). We discuss recent satellite measurements of TSI by ACRIM 2 and 3 And Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) expected from the SORCE mission, planned to launch in fall 2002. SSG has been added to TSI as a required EOS and NPOESS measurement because different spectral components provide energy inputs to different components of the climate system - UV into upper atmosphere and ozone, IR into lower atmosphere and clouds, and Visible into the biosphere. Succeeding satellite missions being planned for 2006 and 2010 will continue to monitor both TSI and SSI. We summarize current ideas about the potential impact of solar variability on Earth's climate on time scales from days to decades to centuries.

  19. Does a slowly varying component of solar irradiance exist?

    NASA Astrophysics Data System (ADS)

    Foukal, P.

    2003-04-01

    Fluctuations of total irradiance, S, caused by sunspots and faculae, are too small (˜0.1%) to force current climate models. Recent reconstructions of S incorporate an additional, slowly varying component, which follows the smoothed spot or group number, or the cycle period. But evidence for this larger (0.2--0.5%) variation, originally based on photometry of sun-like stars, is weakened by recent findings that true solar analog stars are difficult to find. Also, disappearance of the chromospheric network in the early 20th century, implied by these reconstructions, is not observed in archival solar images. I will show some new evidence for an additional component, suggested by the high correlation found between global temperature and the (small-amplitude) variation of S reconstructed using recently digitized facular areas between 1915--1999.The UV irradiance variation modeled from the same data exhibits much lower correlation with global warming, so it is less likely to account for a solar activity signature in 20th century climate. This indirect evidence suggests a mechanism that might amplify the small modulation of S caused specifically by the net effect of bright faculae and dark spots. We now recognize that amplification on multi-decadal time scales could only operate in near- photospheric layers, given the enormous thermal inertia of the deeper solar atmosphere. Also, increasingly tight constraints on such a mechanism are placed by solar photometry and radiometry, by spectro-photometric monitoring of the quiet photospheric effective temperature, and by absence of detectable solar diameter variations. The shrinking set of mechanisms that might satisfy these constraints deserves closer study, and I will discuss some interesting new observational diagnostics, such as bolometric imaging of the photosphere, planned to search for such processes. But at present, little direct evidence exists for a large-amplitude, multi-decadal variation of S (or of UV flux). A

  20. Measurements of Solar Irradiance from a High-Density Radiometer Network

    NASA Astrophysics Data System (ADS)

    Hinkelman, L. M.; Wilcox, S.; Sengupta, M.

    2011-12-01

    Widespread deployment of photovoltaic (PV) energy production systems is currently limited by uncertainty about how high-frequency variability in PV output can be accommodated by the large-scale power grid. Solar flux variability at a point has been shown to cause ramps as high as 1000 Wm-2 over one minute intervals. Several studies have shown that the correlation between the solar irradiance measured at two locations decreases as the distance between the measurement sites increases, indicating that PV array output is smoothed when the array size is increased or the outputs of several stations are combined. However, the level of correlation between sites is a function of meteorological conditions in addition to site separation. Here we present results of a study of irradiance data collected at a high-density radiometer network on Oahu Island. This network contains 17 instruments over an area of about 1 km x 1 km, with station separations ranging from 100 to 1200 m. This unusually high-density network makes it possible to compare irradiances and ramps at the scale of individual PV installations. Using a complete year of measurements, we show ramp statistics for both individual radiometers and simulated plants with capacities of 5-60 MW in terms of absolute irradiance and relative changes. Some seasonal variability is found despite the fairly uniform weather conditions at this location. We also examine the correlations among the time series from all possible combinations of stations at scales from 10 to 300 seconds. A range of results is found from different site pairs at the same distances. For this reason, we separately examine correlations for site pairs oriented along and across the prevailing trade wind direction. Significant differences are found for these two cases, which depend on time scale as well as separation distance. A possible explanation for this finding will be presented in addition to the overall statistical results.

  1. Ionospheric model-observation comparisons: E layer at Arecibo Incorporation of SDO-EVE solar irradiances

    NASA Astrophysics Data System (ADS)

    Sojka, Jan J.; Jensen, Joseph B.; David, Michael; Schunk, Robert W.; Woods, Tom; Eparvier, Frank; Sulzer, Michael P.; Gonzalez, Sixto A.; Eccles, J. Vincent

    2014-05-01

    This study evaluates how the new irradiance observations from the NASA Solar Dynamics Observatory (SDO) Extreme Ultraviolet Variability Experiment (EVE) can, with its high spectral resolution and 10 s cadence, improve the modeling of the E region. To demonstrate this a campaign combining EVE observations with that of the NSF Arecibo incoherent scatter radar (ISR) was conducted. The ISR provides E region electron density observations with high-altitude resolution, 300 m, and absolute densities using the plasma line technique. Two independent ionospheric models were used, the Utah State University Time-Dependent Ionospheric Model (TDIM) and Space Environment Corporation's Data-Driven D Region (DDDR) model. Each used the same EVE irradiance spectrum binned at 1 nm resolution from 0.1 to 106 nm. At the E region peak the modeled TDIM density is 20% lower and that of the DDDR is 6% higher than observed. These differences could correspond to a 36% lower (TDIM) and 12% higher (DDDR) production rate if the differences were entirely attributed to the solar irradiance source. The detailed profile shapes that included the E region altitude and that of the valley region were only qualitatively similar to observations. Differences on the order of a neutral-scale height were present. Neither model captured a distinct dawn to dusk tilt in the E region peak altitude. A model sensitivity study demonstrated how future improved spectral resolution of the 0.1 to 7 nm irradiance could account for some of these model shortcomings although other relevant processes are also poorly modeled.

  2. Quantum dot solar cell tolerance to alpha-particle irradiation

    SciTech Connect

    Cress, Cory D.; Hubbard, Seth M.; Landi, Brian J.; Raffaelle, Ryne P.; Wilt, David M.

    2007-10-29

    The effects of alpha-particle irradiation on an InAs quantum dot (QD) array and GaAs-based InAs QD solar cells were investigated. Using photoluminescence (PL) mapping, the PL intensity at 872 and 1120 nm, corresponding to bulk GaAs and InAs QD emissions, respectively, were measured for a five-layer InAs QD array which had a spatially varying total alpha-particle dose. The spectral response and normalized current-voltage parameters of the solar cells, measured as a function of alpha-particle fluence, were used to investigate the change in device performance between GaAs solar cells with and without InAs QDs.

  3. Deriving historical total solar irradiance from lunar borehole temperatures

    NASA Astrophysics Data System (ADS)

    Miyahara, Hiroko; Wen, Guoyong; Cahalan, Robert F.; Ohmura, Atsumu

    2008-01-01

    We study the feasibility of deriving historical TSI (Total Solar Irradiance) from lunar borehole temperatures. As the Moon lacks Earth's dynamic features, lunar borehole temperatures are primarily driven by solar forcing. Using Apollo observed lunar regolith properties, we computed present-day lunar regolith temperature profiles for lunar tropical, mid-latitude, and polar regions for two scenarios of solar forcing reconstructed by Lean (2000) and Wang et al. (2005). Results show that these scenarios can be distinguished by small but potentially detectable differences in temperature, on the order of 0.01 K and larger depending on latitude, within ~10 m depth of the Moon's surface. Our results provide a physical basis and guidelines for reconstructing historical TSI from data obtainable in future lunar exploration.

  4. Spectral irradiance curve calculations for any type of solar eclipse

    NASA Technical Reports Server (NTRS)

    Deepak, A.; Merrill, J. E.

    1974-01-01

    A simple procedure is described for calculating the eclipse function (EF), alpha, and hence the spectral irradiance curve (SIC), (1-alpha), for any type of solar eclipse: namely, the occultation (partial/total) eclipse and the transit (partial/annular) eclipse. The SIC (or the EF) gives the variation of the amount (or the loss) of solar radiation of a given wavelength reaching a distant observer for various positions of the moon across the sun. The scheme is based on the theory of light curves of eclipsing binaries, the results of which are tabulated in Merrill's Tables, and is valid for all wavelengths for which the solar limb-darkening obeys the cosine law: J = sub c (1 - X + X cost gamma). As an example of computing the SIC for an occultation eclipse which may be total, the calculations for the March 7, 1970, eclipse are described in detail.

  5. Measuring solar spectral and angle-of-incidence effects on photovoltaic modules and solar irradiance sensors

    SciTech Connect

    King, D.L.; Kratochvil, J.A.; Boyson, W.E.

    1997-11-01

    Historically, two time-of-day dependent factors have complicated the characterization of photovoltaic module and array performance; namely, changes in the solar spectrum over the day and optical effects in the module that vary with the solar angle-of-incidence. This paper describes straightforward methods for directly measuring the effects of these two factors. Measured results for commercial modules, as well as for typical solar irradiance sensors (pyranometers) are provided. The empirical relationships obtained from the measurements can be used to improve the methods used for system design, verification of performance after installation, and diagnostic monitoring of performance during operation.

  6. Evaluation of simulated photolysis rates and their response to solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Sukhodolov, Timofei; Rozanov, Eugene; Ball, William T.; Bais, Alkiviadis; Tourpali, Kleareti; Shapiro, Alexander I.; Telford, Paul; Smyshlyaev, Sergey; Fomin, Boris; Sander, Rolf; Bossay, Sébastien; Bekki, Slimane; Marchand, Marion; Chipperfield, Martyn P.; Dhomse, Sandip; Haigh, Joanna D.; Peter, Thomas; Schmutz, Werner

    2016-05-01

    The state of the stratospheric ozone layer and the temperature structure of the atmosphere are largely controlled by the solar spectral irradiance (SSI) through its influence on heating and photolysis rates. This study focuses on the uncertainties in the photolysis rate response to solar irradiance variability related to the choice of SSI data set and to the performance of the photolysis codes used in global chemistry-climate models. To estimate the impact of SSI uncertainties, we compared several photolysis rates calculated with the radiative transfer model libRadtran, using SSI calculated with two models and observed during the Solar Radiation and Climate Experiment (SORCE) satellite mission. The importance of the calculated differences in the photolysis rate response for ozone and temperature changes has been estimated using 1-D a radiative-convective-photochemical model. We demonstrate that the main photolysis reactions, responsible for the solar signal in the stratosphere, are highly sensitive to the spectral distribution of SSI variations. Accordingly, the ozone changes and related ozone-temperature feedback are shown to depend substantially on the SSI data set being used, which highlights the necessity of obtaining accurate SSI variations. To evaluate the performance of photolysis codes, we compared the results of eight, widely used, photolysis codes against two reference schemes. We show that, in most cases, absolute values of the photolysis rates and their response to applied SSI changes agree within 30%. However, larger errors may appear in specific atmospheric regions because of differences, for instance, in the treatment of Rayleigh scattering, quantum yields, or absorption cross sections.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  8. Surface solar irradiance from SCIAMACHY measurements: algorithm and validation

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.; Mueller, R.

    2011-02-01

    Broadband surface solar irradiances (SSI) are, for the first time, derived from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) satellite measurements. The retrieval algorithm, called FRESCO (Fast REtrieval Scheme for Clouds from Oxygen A band) SSI, is similar to the Heliosat method. In contrast to the standard Heliosat method, the cloud index is replaced by the effective cloud fraction derived from the FRESCO cloud algorithm. The MAGIC (Mesoscale Atmospheric Global Irradiance Code) algorithm is used to calculate clear-sky SSI. The SCIAMACHY SSI product is validated against the globally distributed BSRN (Baseline Surface Radiation Network) measurements and compared with the ISCCP-FD (International Satellite Cloud Climatology Project Flux Dataset) surface shortwave downwelling fluxes (SDF). For one year of data in 2008, the mean difference between the instantaneous SCIAMACHY SSI and the hourly mean BSRN global irradiances is -4 W m-2(-1%) with a standard deviation of 101 W m-2 (20%). The mean difference between the globally monthly mean SCIAMACHY SSI and ISCCP-FD SDF is less than -12 W m-2 (-2%) for every month in 2006 and the standard deviation is 62 W m-2 (12%). The correlation coefficient is 0.93 between SCIAMACHY SSI and BSRN global irradiances and is greater than 0.96 between SCIAMACHY SSI and ISCCP-FD SDF. The evaluation results suggest that the SCIAMACHY SSI product achieves similar mean bias error and root mean square error as the surface solar irradiances derived from polar orbiting satellites with higher spatial resolution.

  9. Surface solar irradiance from SCIAMACHY measurements: algorithm and validation

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.; Mueller, R.

    2011-05-01

    Broadband surface solar irradiances (SSI) are, for the first time, derived from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) satellite measurements. The retrieval algorithm, called FRESCO (Fast REtrieval Scheme for Clouds from the Oxygen A band) SSI, is similar to the Heliosat method. In contrast to the standard Heliosat method, the cloud index is replaced by the effective cloud fraction derived from the FRESCO cloud algorithm. The MAGIC (Mesoscale Atmospheric Global Irradiance Code) algorithm is used to calculate clear-sky SSI. The SCIAMACHY SSI product is validated against globally distributed BSRN (Baseline Surface Radiation Network) measurements and compared with ISCCP-FD (International Satellite Cloud Climatology Project Flux Dataset) surface shortwave downwelling fluxes (SDF). For one year of data in 2008, the mean difference between the instantaneous SCIAMACHY SSI and the hourly mean BSRN global irradiances is -4 W m-2 (-1 %) with a standard deviation of 101 W m-2 (20 %). The mean difference between the globally monthly mean SCIAMACHY SSI and ISCCP-FD SDF is less than -12 W m-2 (-2 %) for every month in 2006 and the standard deviation is 62 W m-2 (12 %). The correlation coefficient is 0.93 between SCIAMACHY SSI and BSRN global irradiances and is greater than 0.96 between SCIAMACHY SSI and ISCCP-FD SDF. The evaluation results suggest that the SCIAMACHY SSI product achieves similar mean bias error and root mean square error as the surface solar irradiances derived from polar orbiting satellites with higher spatial resolution.

  10. UV solar irradiance in observations and the NRLSSI and SATIRE-S models

    NASA Astrophysics Data System (ADS)

    Yeo, K. L.; Ball, W. T.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Morrill, J.

    2015-08-01

    Total solar irradiance and UV spectral solar irradiance has been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the variability to solar magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models provide the most comprehensive reconstructions of total and spectral solar irradiance over the period of satellite observation currently available. There is persistent controversy between the various measurements and models in terms of the wavelength dependence of the variation over the solar cycle, with repercussions on our understanding of the influence of UV solar irradiance variability on the stratosphere. We review the measurement and modeling of UV solar irradiance variability over the period of satellite observation. The SATIRE-S reconstruction is consistent with spectral solar irradiance observations where they are reliable. It is also supported by an independent, empirical reconstruction of UV spectral solar irradiance based on Upper Atmosphere Research Satellite/Solar Ultraviolet Spectral Irradiance Monitor measurements from an earlier study. The weaker solar cycle variability produced by NRLSSI between 300 and 400 nm is not evident in any available record. We show that although the method employed to construct NRLSSI is principally sound, reconstructed solar cycle variability is detrimentally affected by the uncertainty in the SSI observations it draws upon in the derivation. Based on our findings, we recommend, when choosing between the two models, the use of SATIRE-S for climate studies.

  11. Development, Production and Validation of the NOAA Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    A new climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), including source code and supporting documentation is now publicly available as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program. Daily and monthly averaged values of TSI and SSI, with associated time and wavelength dependent uncertainties, are estimated from 1882 to the present with yearly averaged values since 1610, updated quarterly for the foreseeable future. The new Solar Irradiance Climate Data Record, jointly developed by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes from quiet Sun conditions when bright faculae and dark sunspots are present on the solar disk. The magnitudes of the irradiance changes that these features produce are determined from linear regression of the proxy Mg II index and sunspot area indices against the approximately decade-long solar irradiance measurements made by instruments on the SOlar Radiation and Climate Experiment (SORCE) spacecraft. We describe the model formulation, uncertainty estimates, operational implementation and validation approach. Future efforts to improve the uncertainty estimates of the Solar Irradiance CDR arising from model assumptions, and augmentation of the solar irradiance reconstructions with direct measurements from the Total and Spectral Solar Irradiance Sensor (TSIS: launch date, July 2017) are also discussed.

  12. Browsing, Understanding, and Accessing Solar Irradiance Data via LISIRD

    NASA Astrophysics Data System (ADS)

    Wilson, A.; Lindholm, D. M.; Pankratz, C. K.

    2012-12-01

    The Laboratory for Atmospheric and Space Physics, LASP, has been conducting research in Atmospheric and Space science for over 60 years. In particular, LASP has made a variety of space-based measurements of solar irradiance, which provide crucial input for research and modeling in solar-terrestrial interactions, space physics, planetary, atmospheric, and climate sciences. These data sets are generally time series of measurements, solar indices, and spectra. Unlike many Earth science data sets, they are not geolocated and so cannot be referenced via latitude and longitude coordinates. Thus they are not appropriate for or interoperable with many existing geo scientific data access and analysis tools and need somewhat specialized tools to aid users in their understanding and use. The LASP Solar Irradiance Data Center, LISIRD, http://lasp.colorado.edu/lisird, is designed to allow the science community and the public to explore and access solar irradiance and related data sets. LISIRD's interactive plotting allows users to investigate and download spectral data sets from a variety of missions. We have recently expanded our offerings and now serve TIMED SEE Level 2, Level 3, and Level 4 data sets. We continue to serve SORCE Solar Spectral Irradiance, Total Solar Irradiance, and Magnesium II and well as the Flare Irradiance Spectral Model (FISM) and other data sets. LISIRD leverages middleware, the LASP Time series Server (LaTiS), that provides access to time series data based on time, wavelength, and parameter. LaTiS can read a wide variety of input formats from both local and remote sources, so many data sets can be served in their native format. It also supports dynamic data reformatting, so users can request the data and times in formats of their choice. LaTiS supports data subsetting so that users may download only regions of interest, and can stream the data directly into a computer program via a RESTful API in an automated fashion. We continue to improve LISIRD not

  13. Diffusion lengths in irradiated N/P InP-on-Si solar cells

    NASA Technical Reports Server (NTRS)

    Wojtczuk, Steven; Colerico, Claudia; Summers, Geoffrey P.; Walters, Robert J.; Burke, Edward A.

    1995-01-01

    Indium phosphide (InP) solar cells are being made on silicon (Si) wafers (InP/Si) to take advantage of both the radiation-hardness properties of the InP solar cell and the light weight and low cost of Si wafers compared to InP or germanium (Ge) wafers. The InP/Si cell application is for long duration and/or high radiation orbit space missions. InP/Si cells have higher absolute efficiency after a high radiation dose than gallium arsenide (GaAs) or silicon (Si) solar cells. In this work, base electron diffusion lengths in the N/P cell are extracted from measured AM0 short-circuit photocurrent at various irradiation levels out to an equivalent 1 MeV fluence of 1017 1 MeV electrons/sq cm for a 1 sq cm 12% BOL InP/Si cell. These values are then checked for consistency by comparing measured Voc data with a theoretical Voc model that includes a dark current term that depends on the extracted diffusion lengths.

  14. A Semantically Enabled Metadata Repository for Solar Irradiance Data Products

    NASA Astrophysics Data System (ADS)

    Wilson, A.; Cox, M.; Lindholm, D. M.; Nadiadi, I.; Traver, T.

    2014-12-01

    The Laboratory for Atmospheric and Space Physics, LASP, has been conducting research in Atmospheric and Space science for over 60 years, and providing the associated data products to the public. LASP has a long history, in particular, of making space-based measurements of the solar irradiance, which serves as crucial input to several areas of scientific research, including solar-terrestrial interactions, atmospheric, and climate. LISIRD, the LASP Interactive Solar Irradiance Data Center, serves these datasets to the public, including solar spectral irradiance (SSI) and total solar irradiance (TSI) data. The LASP extended metadata repository, LEMR, is a database of information about the datasets served by LASP, such as parameters, uncertainties, temporal and spectral ranges, current version, alerts, etc. It serves as the definitive, single source of truth for that information. The database is populated with information garnered via web forms and automated processes. Dataset owners keep the information current and verified for datasets under their purview. This information can be pulled dynamically for many purposes. Web sites such as LISIRD can include this information in web page content as it is rendered, ensuring users get current, accurate information. It can also be pulled to create metadata records in various metadata formats, such as SPASE (for heliophysics) and ISO 19115. Once these records are be made available to the appropriate registries, our data will be discoverable by users coming in via those organizations. The database is implemented as a RDF triplestore, a collection of instances of subject-object-predicate data entities identifiable with a URI. This capability coupled with SPARQL over HTTP read access enables semantic queries over the repository contents. To create the repository we leveraged VIVO, an open source semantic web application, to manage and create new ontologies and populate repository content. A variety of ontologies were used in

  15. Reconstruction of total solar irradiance 1974-2009

    NASA Astrophysics Data System (ADS)

    Ball, W. T.; Unruh, Y. C.; Krivova, N. A.; Solanki, S.; Wenzler, T.; Mortlock, D. J.; Jaffe, A. H.

    2012-05-01

    Context. The study of variations in total solar irradiance (TSI) is important for understanding how the Sun affects the Earth's climate. Aims: Full-disk continuum images and magnetograms are now available for three full solar cycles. We investigate how modelled TSI compares with direct observations by building a consistent modelled TSI dataset. The model, based only on changes in the photospheric magnetic flux can then be tested on rotational, cyclical and secular timescales. Methods: We use Kitt Peak and SoHO/MDI continuum images and magnetograms in the SATIRE-S model to reconstruct TSI over cycles 21-23. To maximise independence from TSI composites, SORCE/TIM TSI data are used to fix the one free parameter of the model. We compare and combine the separate data sources for the model to estimate an uncertainty on the reconstruction and prevent any additional free parameters entering the model. Results: The reconstruction supports the PMOD composite as being the best historical record of TSI observations, although on timescales of the solar rotation the IRMB composite provides somewhat better agreement. Further to this, the model is able to account for 92% of TSI variations from 1978 to 2009 in the PMOD composite and over 96% during cycle 23. The reconstruction also displays an inter-cycle, secular decline of 0.20+0.12-0.09 W m-2 between cycle 23 minima, in agreement with the PMOD composite. Conclusions: SATIRE-S is able to recreate TSI observations on all timescales of a day and longer over 31 years from 1978. This is strong evidence that changes in photospheric magnetic flux alone are responsible for almost all solar irradiance variations over the last three solar cycles.

  16. Diffusion lengths in irradiated N/P InP-on-Si solar cells

    NASA Technical Reports Server (NTRS)

    Wojtczuk, Steven; Colerico, Claudia; Summers, Geoffrey P.; Walters, Robert J.; Burke, Edward A.

    1996-01-01

    Indium phosphide (InP) solar cells were made on silicon (Si) wafers (InP/Si) by to take advantage of both the radiation-hardness properties of the InP solar cell and the light weight and low cost of Si wafers. The InP/Si cell application is for long duration and/or high radiation orbit space missions. Spire has made N/P InP/Si cells of sizes up to 2 cm by 4 cm with beginning-of-life (BOL) AM0 efficiencies over 13% (one-sun, 28C). These InP/Si cells have higher absolute efficiency and power density after a high radiation dose than gallium arsenide (GaAs) or silicon (Si) solar cells after a fluence of about 2e15 1 MeV electrons/sq. cm. In this work, we investigate the minority carrier (electron) base diffusion lengths in the N/P InP/Si cells. A quantum efficiency model was constructed for a 12% BOL AM0 N/P InP/Si cell which agreed well with the absolutely measured quantum efficiency and the sun-simulator measured AM0 photocurrent (30.1 mA/sq. cm). This model was then used to generate a table of AM0 photocurrents for a range of base diffusion lengths. AM0 photocurrents were then measured for irradiations up to 7.7e16 1 MeV electrons/sq. cm (the 12% BOL cell was 8% after the final irradiation). By comparing the measured photocurrents with the predicted photocurrents, base diffusion lengths were assigned at each fluence level. A damage coefficient K of 4e-8 and a starting (unirradiated) base electron diffusion length of 0.8 microns fits the data well. The quantum efficiency was measured again at the end of the experiment to verify that the photocurrent predicted by the model (25.5 mA/sq. cm) agreed with the simulator-measured photocurrent after irradiation (25.7 mA/sq. cm).

  17. Solar EUV Irradiance Measurements by the Auto-Calibrating EUV Spectrometers (SolACES) Aboard the International Space Station (ISS)

    NASA Astrophysics Data System (ADS)

    Schmidtke, G.; Nikutowski, B.; Jacobi, C.; Brunner, R.; Erhardt, C.; Knecht, S.; Scherle, J.; Schlagenhauf, J.

    2014-05-01

    SolACES is part of the ESA SOLAR ISS mission that started aboard the shuttle mission STS-122 on 7 February 2008. The instrument has recorded solar extreme ultraviolet (EUV) irradiance from 16 to 150 nm during the extended solar activity minimum and the beginning solar cycle 24 with rising solar activity and increasingly changing spectral composition. The SOLAR mission has been extended from a period of 18 months to > 8 years until the end of 2016. SolACES is operating three grazing incidence planar grating spectrometers and two three-current ionization chambers. The latter ones are considered as primary radiometric detector standards. Re-filling the ionization chambers with three different gases repeatedly and using overlapping band-pass filters, the absolute EUV fluxes are derived in these spectral intervals. This way the serious problem of continuing efficiency changes in space-borne instrumentation is overcome during the mission. Evaluating the three currents of the ionization chambers, the overlapping spectral ranges of the spectrometers and of the filters plus inter-comparing the results from the EUV photon absorption in the gases with different absorption cross sections, there are manifold instrumental possibilities to cross-check the results providing a high degree of reliability to the spectral irradiance derived. During the mission a very strong up-and-down variability of the spectrometric efficiency by orders of magnitude is observed. One of the effects involved is channeltron degradation. However, there are still open questions on other effects contributing to these changes. A survey of the measurements carried out and first results of the solar spectral irradiance (SSI) data are presented. Inter-comparison with EUV data from other space missions shows good agreement such that the international effort has started to elaborate a complete set of EUV-SSI data taking into account all data available from 2008 to 2013.

  18. Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Kretzschmar, Matthieu; Dammasch, Ingolf E.; Dominique, Marie; Zender, Joe; Cessateur, Gaël; D'Huys, Elke

    2012-08-01

    The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this paper, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE. We find that the solar EUV irradiance has increased by a factor of 2 since the last solar minimum (between solar cycles 23 and 24), which agrees reasonably well with the EVE observations.

  19. Solar EUV irradiance derived from a sounding rocket experiment on November 10, 1988

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.

    1990-05-01

    Results are presented on the solar EUV irradiance measurements in the range 30-100 nm obtained in a sounding rocket experiment launched from the White Sands Missile Range, New Mexico, on November 10, 1988. The observed solar EUV irradiance was found to be about 20 percent less than the solar EUV flux from a proxy model based on the daily 10.7-cm solar flux and its 81-day mean and the AE-E solar EUV data taken in the 1970s. The November 10 measurement of the solar EUV flux provides a good calibration reference spectrum for the solar EUV instruments on the San Marco satellite.

  20. Solar EUV irradiance derived from a sounding rocket experiment on November 10, 1988

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Rottman, Gary J.

    1990-01-01

    Results are presented on the solar EUV irradiance measurements in the range 30-100 nm obtained in a sounding rocket experiment launched from the White Sands Missile Range, New Mexico, on November 10, 1988. The observed solar EUV irradiance was found to be about 20 percent less than the solar EUV flux from a proxy model based on the daily 10.7-cm solar flux and its 81-day mean and the AE-E solar EUV data taken in the 1970s. The November 10 measurement of the solar EUV flux provides a good calibration reference spectrum for the solar EUV instruments on the San Marco satellite.

  1. Simulated solar UV-irradiation of endocrine disrupting chemical octylphenol.

    PubMed

    Neamţu, Mariana; Popa, Dana-Melania; Frimmel, Fritz H

    2009-05-30

    The photolysis of octylphenol (OP) was investigated using a solar simulator in the absence/presence of dissolved natural organic matter (DNOM), HCO(3)(-), NO(3)(-) and Fe(III) ions. The effects of different parameters such as initial pH, initial concentration of substrate, temperature, and the effect of hydrogen peroxide concentration on photodegradation of octylphenol in aqueous solution have been assessed. The results indicate that the oxidation rate increases in the presence of H(2)O(2), nitrate and DNOM. Phenol, 1,4-dihydroxylbenzene and 1,4-benzoquinone were identified as intermediate products of photodegradation of octylphenol, through an HPLC method. In addition, the disappearance of the estrogenic activity of octylphenol during irradiation using YES test was investigated. Based upon the YES test results, there was a strong decrease of estrogenic activity of octylphenol after 8h irradiation in the presence of hydrogen peroxide. PMID:18829169

  2. Panel Discussions on Total Solar Irradiance Variations and the Maunder Minimum

    NASA Technical Reports Server (NTRS)

    Pap, J. M.; White, O. R.

    1993-01-01

    For more than a decade, total solar irradiance has been monitored from several satellites, namely and Nimbus-7, Solar Maximum Mission (SMM), the NASA ERBS, NOAA9 and NOAA10,EURECA, and the Upper Atmospheric Research Satellite (SARS).

  3. Preliminary low temperature electron irradiation of triple junction solar cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2005-01-01

    JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature.

  4. Earth Climate Changes Connected To Solar Diameter and Irradiance Variabilities

    NASA Astrophysics Data System (ADS)

    Lefebvre, S.; Rozelot, J. P.

    Recent studies indicate that small but persistent variations in the total solar irradiance may play an important role in climate changes. If it is known that such changes are mainly due to changes in sunspots darkness and faculae brightness, it begins to be understood that changes in the radius of the Sun may also play a role. In a first part of this paper, we will show how the irradiance is affected by small distortions of the solar shape. Indeed such departures to a pure spherical Sun can be modelized as they reflect the gravitational distortions inside the Sun (variability of the rotation rate both in latitude and in depth as deduced by helioseismic measurements). These departures have been also observed from space (MDI on board SOHO) and from ground (solar astrolabes, scanning heliometer or other means). Such a variability on the Sun's di- ameter, certainly of no more than 40 mas (maybe less), will imply a change in the luminosity of about 6 parts per 10000. For the time being such variations have not been yet taken into account in the Earth climate changes. In the second part of this paper, we will focus on a longer period of time. We will briefly review the variabil- ity of the solar diameter over the last past four centuries, as it is suspected now with a rather good confidence that such a temporal variability may have a sense. We will compare this variability with the global Earth temperatures used as a climatic proxy. It can be seen that diameter changes over such a long period of time are indicative of an external variability on the Earth climate. The physical mechanism involved is obviously through the irradiance changes for which we will emphasize the need to get accurate and simultaneous measurements of the Sun's radius. The determination of the commonly used ratio W, which measures the relative variations of the radius over the relative variations of the irradiance, and as deduced in the first part of this paper, is helpful to pinpoint the source of

  5. Radiation damage in proton irradiated indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Yamaguchi, Masafumi

    1986-01-01

    Indium phosphide solar cells exposed to 10 MeV proton irradiations were found to have significantly greater radiation resistance than either GaAs or Si. Performance predictions were obtained for two proton dominated orbits and one in which both protons and electrons were significant cell degradation factors. Array specific power was calculated using lightweight blanket technology, a SEP array structure, and projected cell efficiencies. Results indicate that arrays using fully developed InP cells should out-perform those using GaAs or Si in orbits where radiation is a significant cell degradation factor.

  6. Solar spectral irradiance and summary outputs using excel.

    PubMed

    Diffey, Brian

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. Photoelectrons as a tool to evaluate spectral and temporal variations of solar EUV and XUV irradiance models over solar rotation and solar cycle time scales

    NASA Astrophysics Data System (ADS)

    Peterson, W. K.; Woods, T. N.; Fontenla, J. M.; Richards, P. G.; Tobiska, W.; Solomon, S. C.; Warren, H. P.

    2010-12-01

    Solar radiation below 50 nm produces a substantial portion of the F region ionization and most of the E region ionization that drives chemical reactions in the thermosphere. Because of a lack of high temporal and spectral resolution Solar EUV and XUV observations, particularly below 27 nm, various solar irradiance models have been developed. We have developed a technique to use observations of escaping photoelectron fluxes from the FAST satellite and two different photoelectron production codes driven by model solar irradiance values to systematically examine differences between observed and calculated escaping photoelectron fluxes. We have compared modeled and observed photoelectron fluxes from the start of TIMED/SEE data availability (2002) to the end of FAST photoelectron observations (2009). Solar irradiance inputs included TIMED/SEE data, which is derived from a model below 27 nm, and the FISM Version 1, the SRPM predictive model based on solar observation, HEUVAC, S2000, and NRL, solar irradiance models. We used the GLOW and FLIP photoelectron production codes. We find that model photoelectron spectra generated using the HEUVAC solar irradiance model have the best overall agreement with observations. Photoelectron spectra generated with the the TIMED/SEE based FISM model best agree with the observations on solar cycle time scales. Below ~27 nm all but the HEUVAC solar irradiance model produces photoelectron fluxes that are systematically below observations. We also noted systematic differences in the photoelectron energy spectra below 25 eV produced by the GLOW and FLIP photoelectron production codes for all solar irradiance inputs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  10. Skin Cancer, Irradiation, and Sunspots: The Solar Cycle Effect

    PubMed Central

    Zurbenko, Igor

    2014-01-01

    Skin cancer is diagnosed in more than 2 million individuals annually in the United States. It is strongly associated with ultraviolet exposure, with melanoma risk doubling after five or more sunburns. Solar activity, characterized by features such as irradiance and sunspots, undergoes an 11-year solar cycle. This fingerprint frequency accounts for relatively small variation on Earth when compared to other uncorrelated time scales such as daily and seasonal cycles. Kolmogorov-Zurbenko filters, applied to the solar cycle and skin cancer data, separate the components of different time scales to detect weaker long term signals and investigate the relationships between long term trends. Analyses of crosscorrelations reveal epidemiologically consistent latencies between variables which can then be used for regression analysis to calculate a coefficient of influence. This method reveals that strong numerical associations, with correlations >0.5, exist between these small but distinct long term trends in the solar cycle and skin cancer. This improves modeling skin cancer trends on long time scales despite the stronger variation in other time scales and the destructive presence of noise. PMID:25126567

  11. Multi-waveband solar irradiance on tree-shaded vertical and horizontal surfaces: cloud-free and partly cloudy skies.

    PubMed

    Grant, R H; Heisler, G M

    2001-01-01

    Irradiance measurements of short wave (SW), photosynthetically active (PAR), ultraviolet-A (UVA) and ultraviolet-B (UVB) solar radiations were made on horizontal and vertical surfaces in the shade of trees under cloud-free and partly cloudy skies. All measurements were referenced to the irradiance of a horizontal surface above the canopy. For horizontal shaded surfaces under cloud-free skies, the values of the ratio (Rh) of below- to above-canopy horizontal irradiance were similar for the UVA and UVB wavebands and for the SW and PAR wavebands. However, Rh for the UV wavebands differed from that for the PAR and SW wavebands. Overall, values of Rh in the shade typically varied as PAR < SW < UVA < UVB. The irradiance ratios for vertical surface in the shade typically varied as UVB > UVA = SW > PAR. In absolute terms, UVB irradiance (Ih) on tree-shaded horizontal surfaces increased relative to a cloud-free sky when a translucent cirroform cloud was in front of the sun, but decreased when the cloud was in a region of sky away from the sun. Translucent cirroform cloud cover also tended to decrease the UVB irradiance (Iv) for a shaded vertical surface (either facing the sun or south) relative to that under cloud-free skies, regardless of where the clouds were in the sky. In all other wavebands the shaded Ih and Iv increased under translucent cirroform cloud cover relative to cloud-free skies, regardless of where the clouds were in the sky. PMID:11202362

  12. The Mg 280-nm doublet as a monitor of changes in solar ultraviolet irradiance

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Schlesinger, B. M.

    1986-01-01

    Solar irradiance data gathered with the Nimbus 7 spacecraft from 1978-1985 are compared with atmospheric MG 289-nm doublet emission line data to evaluate the possibility of using the rotational line data to calculate the total solar UV input. The satellite instrumentation is described, including the calibration equipment and procedures. The spacecraft records solar irradiance once per day and the remainder of the time records irradiance scattered by the atmosphere. The measured irradiances are converted to equivalent brightness temperatures, which can be interpolated for specific layers of the atmosphere. Sample daily data are provided to illustrate the correlation between variations in the Mg-II core radiation and the soalr UV irradiance. Techniques are defined for correcting for periodic variations in instrument performance to quantify long-term solar UV radiance variations. Using the atmospheric Mg-II doublet radiation for measuring soalr UV irradiance is concluded of value for characterizing the effects of solar radiation on the atmosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  14. SME Observations of Solar Ultraviolet Irradiance, October 1981 to April 1989

    NASA Astrophysics Data System (ADS)

    Rottman, G. J.

    2011-12-01

    The primary science objective of the Solar Mesosphere Explorer was to establish the natural relation between solar ultraviolet irradiance and atmospheric ozone. To this end the SME instruments measured both solar spectral irradiance and altitude profiles of ozone from 50 km to 90 km. The Chapman reaction controlling atmospheric ozone production requires solar radiation in the O2 Schumann-Runge and Herzberg bands between 140 nm and 240 nm, and the commensurate ozone destruction involves longer wavelengths in the O3 Hartley band between 230nm and 290nm. The SME solar irradiance spectrometer made daily observations of these relevant spectral bands and extended further down to 115 nm to include Lyman-α. This talk reviews the original SME data and the reported solar variations at both intermediate time scales (especially 27-day variations related to solar rotation) and over the 11-year solar cycle. Recent reprocessing the SME solar data are providing small but important improvements to the data set.

  15. Atmospheric Longwave Irradiance Uncertainty: Pyrgeometers Compared to an Absolute Sky-Scanning Radiometer, Atmospheric Emitted Radiance Interferometer, and Radiative Transfer Model Calculations

    SciTech Connect

    Philipona, J. R.; Dutton, Ellsworth G.; Stoffel, T.; Michalsky, Joseph J.; Reda, I.; Stifter, Armin; Wendling, Peter; Wood, Norm; Clough, Shepard A.; Mlawer, Eli J.; Anderson, Gail; Revercomb, Henry E.; Shippert, Timothy R.

    2001-06-04

    Because atmospheric longwave radiation is one of the most fundamental elements of an expected climate change, there has been a strong interest in improving measurements and model calculations in recent years. Important questions are how reliable and consistent are atmospheric longwave radiation measurements and calculations and what are the uncertainties? The First International Pyrgeometer and Absolute Sky-scanning Radiometer Comparison, which was held at the Atmospheric Radiation Measurement program's Souther Great Plains site in Oklahoma, answers these questions at least for midlatitude summer conditions and reflects the state of the art for atmospheric longwave radiation measurements and calculations. The 15 participating pyrgeometers were all calibration-traced standard instruments chosen from a broad international community. Two new chopped pyrgeometers also took part in the comparison. And absolute sky-scanning radiometer (ASR), which includes a pyroelectric detector and a reference blackbody source, was used for the first time as a reference standard instrument to field calibrate pyrgeometers during clear-sky nighttime measurements. Owner-provided and uniformly determined blackbody calibration factors were compared. Remarkable improvements and higher pyrgeometer precision were achieved with field calibration factors. Results of nighttime and daytime pyrgeometer precision and absolute uncertainty are presented for eight consecutive days of measurements, during which period downward longwave irradiance varied between 260 and 420 W m-2. Comparisons between pyrgeometers and the absolute ASR, the atmospheric emitted radiance interferometer, and radiative transfer models LBLRTM and MODTRAN show a surprisingly good agreement of <2 W m-2 for nighttime atmospheric longwave irradiance measurements and calculations.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. Analysis of clear hour solar irradiation for seven Canadian stations

    SciTech Connect

    Garrison, J.; Sahami, K.

    1995-12-31

    Hourly global and diffuse irradiation and corresponding surface meteorological data have been analyzed for the seven Canadian stations at Edmonton, Goose Bay, Montreal, Port Hardy, Resolute, Toronto, and Winnipeg. The variation of the most probable clear hour values of clearness index k{sub t}, diffuse index k{sub d}, direct beam index k{sub b}, and Angstrom turbidity coefficient {beta} with solar elevation, atmospheric precipitable water, and snow depth are obtained. Values of these quantities are presented which are consistent with the attenuation and scattering of solar radiation by the atmosphere which is expected. The most probable values of {beta} tend to be lower than the average values of {beta} recently reported by Gueymard. The data indicate a drift in the calibration of the instruments used for measurements of the irradiation data for the stations at Goose Bay and Resolute. The data for the other five stations indicate that the instrument calibration is maintained over the years of the data. 4 refs., 8 figs., 5 tabs.

  18. Atmospheric Sensitivity to Spectral Top-of-Atmosphere Solar Irradiance Perturbations, Using MODTRAN-5 Radiative Transfer Algorithm

    NASA Astrophysics Data System (ADS)

    Anderson, G.; Berk, A.; Harder, G.; Fontenla, J.; Shettle, E.; Pilewski, P.; Kindel, B.; Chetwynd, J.; Gardner, J.; Hoke, M.; Jordan, A.; Lockwood, R.; Felde, G.; Archarya, P.

    2006-12-01

    expected to be very small in visible wavelengths, although absolute power is substantial. SORCE's Spectral Irradiance Monitor measurements are readily included in comparative MOD5 calculations. (2) The embedded solar irradiance within MOD5 must be compatible with the chosen band model resolution binning. By matching resolutions some issues related to the correlated-k band model parameterizations can be tested. Two high resolution solar irradiances, the MOD5 default irradiance (Kurucz) and a new compilation associated with Solar Radiation Physical Modeling project (Fontenla), are compared to address the potential impact of discrepancies between any sets of irradiances. The magnitude of solar variability, as measured and calculated, can lead to subtle changes in heating/cooling rates throughout the atmosphere, as a function of altitude and wavelength. By holding chemical & dynamical responses constant, only controlled distributions of absorbing gases, aerosols and clouds will contribute to observed 1st order radiative effects.

  19. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

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

  20. Photoelectrons as a tool to evaluate solar EUV and XUV model irradiance spectra

    NASA Astrophysics Data System (ADS)

    Peterson, W. K.; Woods, T. N.; Fontenla, J. M.; Richards, P. G.; Tobiska, W.; Solomon, S. C.; Warren, J.

    2011-12-01

    Solar radiation below 50 nm produces a substantial portion of the F region ionization and most of the E region ionization that drives chemical reactions in the thermosphere. At times before the launch of the SDO spacecraft there is a lack of high temporal and spectral resolution Solar EUV and XUV observations, particularly below 27 nm. To address the space data various solar irradiance models have been developed. We have developed a technique to use observations of escaping photoelectron fluxes from the FAST satellite and two different photoelectron production codes driven by model solar irradiance values to systematically examine differences between observed and calculated escaping photoelectron fluxes. We have compared modeled and observed photoelectron fluxes for the interval from September 14, 2006 to January 1, 2007. This is an interval included ~ 4 solar rotations and is characterized by modest solar and geomagnetic activity. Solar irradiance models included TIMED/SEE data, which is derived from a model below 27 nm, and the FISM Version 1, the SRPM predictive model based on solar observation, HEUVAC, S2000, and NRL, solar irradiance models. We used the GLOW and FLIP photoelectron production codes. Here we focus on the differences between solar irradiance models and small differences between photoelectron production code outputs using the same solar irradiance spectra over this time period.

  1. Comparison of model estimated and measured direct-normal solar irradiance

    SciTech Connect

    Halthore, R.N.; Schwartz, S.E.; Michalsky, J.J.; Anderson, G.P.; Holben, B.N.; Ten Brink, H.M.

    1997-12-01

    Direct-normal solar irradiance (DNSI), the energy in the solar spectrum incident in unit time at the Earth{close_quote}s surface on a unit area perpendicular to the direction to the Sun, depends only on atmospheric extinction of solar energy without regard to the details of the extinction, whether absorption or scattering. Here we report a set of closure experiments performed in north central Oklahoma in April 1996 under cloud-free conditions, wherein measured atmospheric composition and aerosol optical thickness are input to a radiative transfer model, MODTRAN 3, to estimate DNSI, which is then compared with measured values obtained with normal incidence pyrheliometers and absolute cavity radiometers. Uncertainty in aerosol optical thickness (AOT) dominates the uncertainty in DNSI calculation. AOT measured by an independently calibrated Sun photometer and a rotating shadow-band radiometer agree to within the uncertainties of each measurement. For 36 independent comparisons the agreement between measured and model-estimated values of DNSI falls within the combined uncertainties in the measurement (0.3{endash}0.7{percent}) and model calculation (1.8{percent}), albeit with a slight average model underestimate ({minus}0.18{plus_minus}0.94){percent}; for a DNSI of 839Wm{sup {minus}2} this corresponds to {minus}1.5{plus_minus}7.9Wm{sup {minus}2}. The agreement is nearly independent of air mass and water-vapor path abundance. These results thus establish the accuracy of the current knowledge of the solar spectrum, its integrated power, and the atmospheric extinction as a function of wavelength as represented in MODTRAN 3. An important consequence is that atmospheric absorption of short-wave energy is accurately parametrized in the model to within the above uncertainties. {copyright} 1997 American Geophysical Union

  2. Sensitivity of the photolysis rate to the uncertainties in spectral solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Sukhodolov, Timofei; Rozanov, Eugene; Bais, Alkiviadis; Tourpali, Kleareti; Shapiro, Alexander; Telford, Paul; Peter, Thomas; Schmutz, Werner

    2014-05-01

    The state of the stratospheric ozone layer and temperature structure are mostly maintained by the photolytical processes. Therefore, the uncertainties in the magnitude and spectral composition of the spectral solar irradiance (SSI) evolution during the declining phase of 23rd solar cycle have substantial implications for the modeling of the middle atmosphere evolution, leading not only to a pronounced differences in the heating rates but also affecting photolysis rates. To estimate the role of SSI uncertainties we have compared the most important photolysis rates (O2, O3, and NO2) calculated with the reference radiation code libRadtran using SSI for June 2004 and February 2009 obtained from two models (NRL, COSI) and one observation data set based on SORCE observations. We found that below 40 km changes in the ozone and oxygen photolysis can reach several tenths of % caused by the changes of the SSI in the Harley and Huggins bands for ozone and several % for oxygen caused by the changes of the SSI in the Herzberg continuum and Schumann-Runge bands. For the SORCE data set these changes are 2-4 times higher. We have also evaluated the ability of the several photolysis rates calculation methods widely used in atmospheric models to reproduce the absolute values of the photolysis rates and their response to the implied SSI changes. With some remarks all schemes show good results in the middle stratosphere compare to libRadtran. However, in the troposphere and mesosphere there are more noticeable differences.

  3. ACRIM3 and the Total Solar Irradiance database

    NASA Astrophysics Data System (ADS)

    Willson, Richard C.

    2014-08-01

    The effects of scattering and diffraction on the observations of the ACRIMSAT/ACRIM3 satellite TSI monitoring mission have been characterized by the preflight calibration approach for satellite total solar irradiance (TSI) sensors implemented at the LASP/TRF (Laboratory for Atmospheric and Space Physics/Total Solar Irradiance Radiometer Facility). The TRF also calibrates the SI (International System of units) traceability to the NIST (National Institute of Standards and Technology) cryo-radiometric scale. ACRIM3's self-calibration agrees with NIST to within the uncertainty of the test procedure (˜500 ppm). A correction of ˜5000 ppm was found for scattering and diffraction that has significantly reduced the scale difference between the results of the ACRIMSAT/ACRIM3 and SORCE/TIM satellite experiments. Algorithm updates reflecting more than 10 years of mission experience have been made that further improve the ACRIM3 results by eliminating some thermally driven signal and increasing the signal to noise ratio. The result of these changes is a more precise and detailed picture of TSI variability. Comparison of the results from the ACRIM3, SORCE/TIM and SOHO/VIRGO satellite experiments demonstrate the near identical detection of TSI variability on all sub-annual temporal and amplitude scales during the TIM mission. The largest occurs at the rotational period of the primary solar activity longitudes. On the decadal timescale, while ACRIM3 and VIRGO results exhibit close agreement throughout, TIM exhibits a consistent 500 ppm upward trend relative to ACRIM3 and VIRGO. A solar magnetic activity area proxy for TSI has been used to demonstrate that the ACRIM TSI composite and its +0.037 %/decade TSI trend during solar cycles 21-23 is the most likely correct representation of the extant satellite TSI database. The occurrence of this trend during the last decades of the 20th century supports a more robust contribution of TSI variation to detected global temperature increase

  4. A proposed update to the solar irradiance spectrum used in LOWTRAN and MODTRAN

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Gao, Bo-Cai

    1993-01-01

    The calibrated upwelling radiance spectra measured by AVIRIS are increasingly being analyzed with radiative transfer codes. Analysis of AVIRIS data with the LOWTRAN and MODTRAN radiative transfer codes has led to indications of an error in the solar irradiance spectra used by these codes. This paper presents evidence for the error and proposed update to the solar irradiance spectra used by LOWTRAN and MODTRAN.

  5. Do Flares Contribute to Total Solar Irradiance Variability ?

    NASA Astrophysics Data System (ADS)

    Kretzschmar, M.; Dudok de Wit, T.

    2010-12-01

    The Total Solar Irradiance (TSI) varies on all time scales and a major fraction of its variability can be reproduced by considering the appearance and disappearance of features, such as sunspots and faculae, on the solar disk. Other effects (e.g. the so called network), however, are contributing to the variability of the TSI, as evidenced by its unusually low level during the last solar minimum. Here we show that flares of various amplitudes also have a significant impact on the TSI. In contrast to standard belief, the dominant contribution comes from the visible domain. We next estimate the probability distribution of flares versus their total radiative output; previous estimates were restricted to a specific spectral range only (e.g. in the soft X-ray or radio domain) whereas we consider the total energy. The obtained distribution follows a power law; we investigate the possibility of small flares to have a major contribution to the TSI variability. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SOTERIA (project n° 218816, www.soteria-space.eu)

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

    SciTech Connect

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

    1996-04-01

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

  7. [Optical multi-channel detection and analysis on solar ultra-violet irradiance spectrum].

    PubMed

    Zhao, Xiao-yan; He, Jie; Zuo, Hao-yi; Liang, Hui-min; Yang, Jing-guo

    2007-05-01

    The present paper reports a new type of ultraviolet CCD optical multi-channel analyzer and its application to detecting solar ultraviolet irradiance spectrum. Spectral detecting range of 200-1 100 nm, spectral resolution of 0.1 nm and detecting sensitivity of 0.02 lx were reached in this instrument. The solar spectra of UVB and UVA were measured in real time in Chengdu area. The measurement results have good correlation with the detection using normal solar ultraviolet irradiance detector. Primary analysis on the detection results of solar spectra in UVB and UVA indicated that in the morning and in the afternoon the irradiance of solar ultraviolet is smaller than that at noon, and reverse correlation holds for the change of SZA (Solar Zenith Angle). In different wavelength interval of UVA and UVB, generally, the radiation flux of long wavelength is greater than that of short. Clouds and aerosols in the atmosphere have important influence on ultraviolet irradiance. PMID:17655086

  8. Prediction of global solar irradiance based on time series analysis: Application to solar thermal power plants energy production planning

    SciTech Connect

    Martin, Luis; Marchante, Ruth; Cony, Marco; Zarzalejo, Luis F.; Polo, Jesus; Navarro, Ana

    2010-10-15

    Due to strong increase of solar power generation, the predictions of incoming solar energy are acquiring more importance. Photovoltaic and solar thermal are the main sources of electricity generation from solar energy. In the case of solar thermal energy plants with storage energy system, its management and operation need reliable predictions of solar irradiance with the same temporal resolution as the temporal capacity of the back-up system. These plants can work like a conventional power plant and compete in the energy stock market avoiding intermittence in electricity production. This work presents a comparisons of statistical models based on time series applied to predict half daily values of global solar irradiance with a temporal horizon of 3 days. Half daily values consist of accumulated hourly global solar irradiance from solar raise to solar noon and from noon until dawn for each day. The dataset of ground solar radiation used belongs to stations of Spanish National Weather Service (AEMet). The models tested are autoregressive, neural networks and fuzzy logic models. Due to the fact that half daily solar irradiance time series is non-stationary, it has been necessary to transform it to two new stationary variables (clearness index and lost component) which are used as input of the predictive models. Improvement in terms of RMSD of the models essayed is compared against the model based on persistence. The validation process shows that all models essayed improve persistence. The best approach to forecast half daily values of solar irradiance is neural network models with lost component as input, except Lerida station where models based on clearness index have less uncertainty because this magnitude has a linear behaviour and it is easier to simulate by models. (author)

  9. Soft X-ray irradiance measured by the Solar Aspect Monitor on the Solar Dynamic Observatory Extreme ultraviolet Variability Experiment

    NASA Astrophysics Data System (ADS)

    Lin, C. Y.; Bailey, S. M.; Jones, A.; Woodraska, D.; Caspi, A.; Woods, T. N.; Eparvier, F. G.; Wieman, S. R.; Didkovsky, L. V.

    2016-04-01

    The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme ultraviolet Variability Experiment (EVE) aboard the Solar Dynamics Observatory. SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass. Contamination from energetic particles and out-of-band irradiance is, however, significant in the SAM observations. We present a technique for isolating the 0.01-7 nm integrated irradiance from the SAM signal to produce the first results of broadband irradiance for the time period from May 2010 to May 2014. The results of this analysis agree with a similar data product from EVE's EUV SpectroPhotometer to within 25%. We compare our results with measurements from the Student Nitric Oxide Explorer Solar X-ray Photometer and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics Solar EUV Experiment at similar levels of solar activity. We show that the full-disk SAM broadband results compared well to the other measurements of the 0.01-7 nm irradiance. We also explore SAM's capability toward resolving spatial contribution from regions of solar disk in irradiance and demonstrate this feature with a case study of several strong flares that erupted from active regions on 11 March 2011.

  10. How does clear-sky terrestrial irradiance vary with solar activity?

    NASA Astrophysics Data System (ADS)

    Feulner, Georg

    2013-04-01

    I investigate recent claims for a strong variation of clear-sky terrestrial solar irradiance with solar activity (on the level of O(1%) over the 11-year cycle) derived from ground-based observations of the Sun. As it turns out, these erroneous results arise because important effects like the dimming by volcanic aerosols and long-term changes in atmospheric transmission independent of solar activity have to be corrected for. After taking these into account, clear-sky terrestrial solar irradiance can be shown to vary by O(0.1%) as expected from satellite-based measurements of the changes in Total Solar Irradiance over the solar cycle. On the one hand this example illustrates the usefulness of ground-based monitoring of solar irradiance data, but on the other hand it highlights the difficulties which can hamper an unbiased analysis of such datasets. References Feulner, G., 2011: The Smithsonian solar constant data revisited: no evidence for a strong effect of solar activity in ground-based insolation data, Atmos. Chem. Phys., 11, 3291-3301, doi:10.5194/acp-11-3291-2011 Feulner, G., 2013: On the relation between solar activity and clear-sky terrestrial irradiance, Solar Phys., 282, 615-627, doi:10.1007/s11207-012-0129-z

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Solar EUV irradiance during solar cycle 24 as observed by PROBA2/LYRA and SDO/EVE

    NASA Astrophysics Data System (ADS)

    Kretzschmar, Matthieu; Dominique, Marie; Dammasch, Ingolf

    2013-04-01

    Solar EUV irradiance affects the upper atmospheres of planets and is a fundamental parameters for space weather. The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this presentation, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE and several proxies.

  13. Detectability of active triangulation range finder: a solar irradiance approach.

    PubMed

    Liu, Huizhe; Gao, Jason; Bui, Viet Phuong; Liu, Zhengtong; Lee, Kenneth Eng Kian; Peh, Li-Shiuan; Png, Ching Eng

    2016-06-27

    Active triangulation range finders are widely used in a variety of applications such as robotics and assistive technologies. The power of the laser source should be carefully selected in order to satisfy detectability and still remain eye-safe. In this paper, we present a systematic approach to assess the detectability of an active triangulation range finder in an outdoor environment. For the first time, we accurately quantify the background noise of a laser system due to solar irradiance by coupling the Perez all-weather sky model and ray tracing techniques. The model is validated with measurements with a modeling error of less than 14.0%. Being highly generic and sufficiently flexible, the proposed model serves as a guide to define a laser system for any geographical location and microclimate. PMID:27410637

  14. ABSOLUTE PROPERTIES OF THE HIGHLY ECCENTRIC, SOLAR-TYPE ECLIPSING BINARY HD 74057

    SciTech Connect

    Sowell, James R.; Henry, Gregory W.; Fekel, Francis C. E-mail: gregory.w.henry@gmail.com

    2012-01-15

    We have obtained Stroemgren b and y differential photometric observations of the solar-type eclipsing binary HD 74057 plus follow-up high-resolution, red wavelength spectroscopic observations. The system has an orbital period of 31.2198 days, a high eccentricity of 0.47, and is seen almost exactly edge on with an inclination of 89.{sup 0}8. The two main-sequence G0 stars are nearly identical in all physical characteristics. We used the Wilson-Devinney program to obtain a simultaneous solution of our photometric and spectroscopic observations. The resulting masses of the components are M{sub 1} = 1.138 {+-} 0.003 M{sub Sun} and M{sub 2} = 1.131 {+-} 0.003 M{sub Sun }, and the radii are R{sub 1} = 1.064 {+-} 0.002 R{sub Sun} and R{sub 2} = 1.049 {+-} 0.002 R{sub Sun }. The effective temperatures are 5900 K (fixed) and 5843 K, and the iron abundance, [Fe/H], is estimated to be +0.07. A comparison with evolutionary tracks suggests that the system may be even more metal rich. The components rotate with periods of 8.4 days, significantly faster than the predicted pseudosynchronous period of 12.7 days. We see evidence that one or both components have cool spots. Both stars are close to the zero-age main sequence and are about 1.0 Gyr old.

  15. Modelling total solar irradiance since 1878 from simulated magnetograms

    NASA Astrophysics Data System (ADS)

    Dasi-Espuig, M.; Jiang, J.; Krivova, N. A.; Solanki, S. K.

    2014-10-01

    Aims: We present a new model of total solar irradiance (TSI) based on magnetograms simulated with a surface flux transport model (SFTM) and the Spectral And Total Irradiance REconstructions (SATIRE) model. Our model provides daily maps of the distribution of the photospheric field and the TSI starting from 1878. Methods: The modelling is done in two main steps. We first calculate the magnetic flux on the solar surface emerging in active and ephemeral regions. The evolution of the magnetic flux in active regions (sunspots and faculae) is computed using a surface flux transport model fed with the observed record of sunspot group areas and positions. The magnetic flux in ephemeral regions is treated separately using the concept of overlapping cycles. We then use a version of the SATIRE model to compute the TSI. The area coverage and the distribution of different magnetic features as a function of time, which are required by SATIRE, are extracted from the simulated magnetograms and the modelled ephemeral region magnetic flux. Previously computed intensity spectra of the various types of magnetic features are employed. Results: Our model reproduces the PMOD composite of TSI measurements starting from 1978 at daily and rotational timescales more accurately than the previous version of the SATIRE model computing TSI over this period of time. The simulated magnetograms provide a more realistic representation of the evolution of the magnetic field on the photosphere and also allow us to make use of information on the spatial distribution of the magnetic fields before the times when observed magnetograms were available. We find that the secular increase in TSI since 1878 is fairly stable to modifications of the treatment of the ephemeral region magnetic flux.

  16. NEW SOLAR EXTREME-ULTRAVIOLET IRRADIANCE OBSERVATIONS DURING FLARES

    SciTech Connect

    Woods, Thomas N.; Hock, Rachel; Eparvier, Frank; Jones, Andrew R.; Chamberlin, Phillip C.; Klimchuk, James A.; Didkovsky, Leonid; Judge, Darrell; Mariska, John; Warren, Harry; Schrijver, Carolus J.; Webb, David F.; Bailey, Scott; Tobiska, W. Kent

    2011-10-01

    New solar extreme-ultraviolet (EUV) irradiance observations from the NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment provide full coverage in the EUV range from 0.1 to 106 nm and continuously at a cadence of 10 s for spectra at 0.1 nm resolution and even faster, 0.25 s, for six EUV bands. These observations can be decomposed into four distinct characteristics during flares. First, the emissions that dominate during the flare's impulsive phase are the transition region emissions, such as the He II 30.4 nm. Second, the hot coronal emissions above 5 MK dominate during the gradual phase and are highly correlated with the GOES X-ray. A third flare characteristic in the EUV is coronal dimming, seen best in the cool corona, such as the Fe IX 17.1 nm. As the post-flare loops reconnect and cool, many of the EUV coronal emissions peak a few minutes after the GOES X-ray peak. One interesting variation of the post-eruptive loop reconnection is that warm coronal emissions (e.g., Fe XVI 33.5 nm) sometimes exhibit a second large peak separated from the primary flare event by many minutes to hours, with EUV emission originating not from the original flare site and its immediate vicinity, but rather from a volume of higher loops. We refer to this second peak as the EUV late phase. The characterization of many flares during the SDO mission is provided, including quantification of the spectral irradiance from the EUV late phase that cannot be inferred from GOES X-ray diagnostics.

  17. Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Cessateur, G.; Shapiro, A. I.; Dominique, M.; Kretzschmar, M.; Krivova, N.; Shapiro, A. V.; Schmutz, W.; Schoell, M.; Solanki, S.; Tagirov, R.; Thuillier, G.; Wehrli, C.; Yeo, K. L.

    2012-04-01

    Total and Spectral Solar Irradiance are key input parameters to atmospheric/oceanic and space weather models. Both vary on time-scales ranging from days to millennia, although a complete picture of the solar irradiance variability is still missing. The recent launch of two European missions PROBA-2 with LYRA radiometer onboard and PICARD with PREMOS package onboard provides therefore valuable information and nourishes theoretical models. Both instruments covers the solar spectrum from the EUV to near-infrared. Here we present spectral solar irradiance data from these two recent missions. After a proper correction of the degradation and non-solar signatures, we compare these data with those from the VIRGO/SOHO and SOLSTICE+SIM/SORCE experiments. Both LYRA and PREMOS have also observed several solar eclipses, which allows us to accurately retrieve the center-to-limb variations (CLVs) of the quiet Sun's brightness at the wavelengths of the corresponding channels. CLVs play indeed an important role in modelling of the solar irradiance variability. We show that calculations with the published COde for Solar Irradiance (COSI) yield CLVs that are in good agreement with measurements. Finally we use COSI to model the variability of the irradiance, assuming that the latter is determined by the evolution of the solar surface magnetic field as seen with SDO/HMI data. These theoretical results are compared to PREMOS and LYRA measurements.

  18. The variations of geomagnetic energy and solar irradiance and their impacts on Earth's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Huang, Yanshi

    2012-10-01

    It is important to understand and estimate the energy inputs to the upper atmosphere, in order to provide accurate calculation and prediction of the thermospheric neutral density, which is important for satellite orbital determination. The primary energy sources of Earth's upper atmosphere are the solar irradiance and geomagnetic energy including Joule heating and particle precipitation. Various data (OMNI2, CHAMP, DMSP) and models (SOLAR2000, FISM, Weimer05, AMIE, NCAR TIE-GCM) are utilized to investigate the variations of energy inputs and their influences on the coupled thermosphere-ionosphere system, with focus on the wavelength dependence of solar irradiance enhancement during are events, the geomagnetic energy associated with high-speed solar wind streams, the altitudinal distribution of Joule heating in different solar conditions, and the variation of solar irradiance and geomagnetic energy inputs during last solar cycle.

  19. 18-months of UV irradiance observations from the Solar Mesosphere Explorer

    NASA Technical Reports Server (NTRS)

    London, J.; Bjarnason, G. G.; Rottman, G. J.

    1984-01-01

    An instrument on the Solar Mesosphere Explorer has been making daily solar irradiance measurements in the 120-305 nm (UV) spectral interval since October 6, 1981. Calculations of the highest to lowest value of the irradiance within each solar rotation yield percent range values indicative of variations that are useful as input data for model calculations of stratosphere/mesosphere responses to short period solar variability, since solar radiation in the UV is largely responsible for the photochemical interactions and radiative heating of the stratosphere, mesosphere, and lower thermosphere.

  20. A Collaborative FP7 Effort towards the First European Comprehensive SOLar Irradiance Data Exploitation (SOLID)

    NASA Astrophysics Data System (ADS)

    Haberreiter, Margit; Dasi, Maria; Delouille, Veronique; Del Zanna, Giulio; Dudok de Wit, Thierry; Ermolli, Ilaria; Kretzschmar, Matthieu; Krivova, Natalie; Mason, Helen; Qahwaji, Rami; Schmutz, Werner; Solanki, Sami; Thuillier, Gerard; Tourpali, Kleareti; Unruh, Yvonne; Verbeeck, Cis; Weber, Mark; Woods, Tom

    2013-04-01

    Variations of solar irradiance are the most important natural factor in the terrestrial climate and as such, the time dependent spectral solar irradiance is a crucial input to any climate modelling. There have been previous efforts to compile solar irradiance but it is still uncertain by how much the spectral and total solar irradiance changed on yearly, decadal and longer time scales. Observations of irradiance data exist in numerous disperse data sets. Therefore, it is important to bring together the European expertise in the field to analyse and merge the complete set of European irradiance data, complemented by archive data that include data from non-European missions. We report on the initiation of a collaborative effort to unify representatives from all European solar space experiments and European teams specialized in multi-wavelength solar image processing. It is intended to include the European groups involved in irradiance modelling and reconstruction. They will work with two different state of the art approaches to produce reconstructed spectral and total solar irradiance data as a function of time. These results will be used to bridge gaps in time and wavelength coverage of the observational data. This will allow the proposing SOLID team to reduce the uncertainties in the irradiance time series - an important requirement by the climate community - and to provide uniform data sets of modelled and observed solar irradiance data from the beginning of the space era to the present including proper error and uncertainty estimates. Climate research needs these data sets and therefore, the primary benefit is for the climate community, but the stellar community, planetary, lunar, and ionospheric researchers are also interested in having at their disposition incident radiation of the Sun. The proposing team plans to realize a wide international synergy in solar physics from 7 European countries, and collaborators from the US, complemented by representatives from

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

    NASA Astrophysics Data System (ADS)

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

    1982-09-01

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

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

    SciTech Connect

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

    1982-09-01

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

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

    PubMed

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

    2004-01-01

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

  4. Numerical modeling of solar irradiance on earth's surface

    NASA Astrophysics Data System (ADS)

    Mera, E.; Gutierez, L.; Da Silva, L.; Miranda, E.

    2016-05-01

    Modeling studies and estimation of solar radiation in base area, touch from the problems of estimating equation of time, distance equation solar space, solar declination, calculation of surface irradiance, considering that there are a lot of studies you reported the inability of these theoretical equations to be accurate estimates of radiation, many authors have proceeded to make corrections through calibrations with Pyranometers field (solarimeters) or the use of satellites, this being very poor technique last because there a differentiation between radiation and radiant kinetic effects. Because of the above and considering that there is a weather station properly calibrated ground in the Susques Salar in the Jujuy Province, Republic of Argentina, proceeded to make the following modeling of the variable in question, it proceeded to perform the following process: 1. Theoretical Modeling, 2. graphic study of the theoretical and actual data, 3. Adjust primary calibration data through data segmentation on an hourly basis, through horizontal and adding asymptotic constant, 4. Analysis of scatter plot and contrast series. Based on the above steps, the modeling data obtained: Step One: Theoretical data were generated, Step Two: The theoretical data moved 5 hours, Step Three: an asymptote of all negative emissivity values applied, Solve Excel algorithm was applied to least squares minimization between actual and modeled values, obtaining new values of asymptotes with the corresponding theoretical reformulation of data. Add a constant value by month, over time range set (4:00 pm to 6:00 pm). Step Four: The modeling equation coefficients had monthly correlation between actual and theoretical data ranging from 0.7 to 0.9.

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

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1983-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

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

  7. Space observations of the variability of solar irradiance in the near and far ultraviolet

    NASA Technical Reports Server (NTRS)

    Heath, D. F.

    1972-01-01

    Satellite observations of the ultraviolet solar irradiance in selected wavelength bands between 1200 and 3000 a were made continuously by photometers consisting of broad-band sensors operated on Numbus 3 and 4 which were launched in April 1969 and 1970. In addition, spectrophotometer measurements of the solar irradiance were made with a dispersive instrument at 12 selected wavelengths from 2550 to 3400 a with a 10 a bandpass on Nimbus 4. Variations of the solar irradiance associated with the solar rotational period were observed since the launch of Nimbus 3. These variations are apparently associated with two source regions separated by about 180 deg in solar longitude. The change in irradiance with solar rotation was found to increase with decreasing wavelengths. Different types of the observed variations in uv solar irradiance can be classified in accordance with characteristics times, e.g. in the order of increasing periods as follows: (1)flare associated enhancements (2) 27-day variations due to solar rotation; (3) a possible biennial effect; and (4) long term variations associated with the 11-year solar cycle.

  8. Absolute isotopic composition of molybdenum and the solar abundances of the p-process nuclides Mo92,94

    NASA Astrophysics Data System (ADS)

    Wieser, M. E.; de Laeter, J. R.

    2007-05-01

    The isotopic composition of molybdenum has been measured with high precision using a thermal ionization mass spectrometer, the linearity of which has been verified by measuring the isotopically-certified reference material for strontium (NIST 987). The abundance sensitivity of the mass spectrometer in the vicinity of the molybdenum ion beams has been carefully examined to ensure the absence of tailing effects. Particular care was given to ensuring that potential isobaric interferences from zirconium and ruthenium did not affect the measurement of the isotopic composition of molybdenum. Gravimetric mixtures of two isotopically enriched isotopes, Mo92 and Mo98, were analyzed mass spectrometrically to calibrate the mass spectrometer, in order to establish the isotope fractionation of the spectrometer for the molybdenum isotopes. This enabled the “absolute” isotopic composition of molybdenum to be determined. An accurate determination of the isotopic composition is required in order to calculate the atomic weight of molybdenum, which is one of the least accurately known values of all the elements. The absolute isotope abundances (in atom %) of molybdenum measured in this experiment are as follows: Mo92=14.5246±0.0015; Mo94=9.1514±0.0074; Mo95=15.8375±0.0098; Mo96=16.672±0.019; Mo97=9.5991±0.0073; Mo98=24.391±0.018; and Mo100=9.824±0.050, with uncertainties at the 1s level. These values enable an atomic weight Ar(Mo) of 95.9602±0.0023 (1s) to be calculated, which is slightly higher than the current Standard Atomic Weight Ar(Mo) =95.94±0.02 and with a much improved uncertainty interval. These “absolute” isotope abundances also enable the Solar System abundances of molybdenum to be calculated for astrophysical purposes. Of particular interest are the Solar System abundances of the two p-process nuclides—Mo92 and Mo94, which are present in far greater abundance than p-process theory suggests. The Solar System abundances for Mo92 and Mo94 of 0.364±0

  9. Differences Between the Response of the Equatorial TEC and foF2 to Solar Soft X-ray Irradiances

    NASA Astrophysics Data System (ADS)

    Wang, X.; Eastes, R.; Reinisch, B. W.; Bailey, S.; Valladares, C.; Woods, T.

    2005-12-01

    Measurements of the solar soft X-ray irradiances from the SNOE satellite; the TEC from Ancon, Peru; and the foF2 from Jicamarca, Peru have been compared for a period of almost two years. While both TEC and foF2 have a significant response to changes in the solar irradiances, each responds differently. At noon time, solar irradiances have a stronger correlation with TEC than with foF2 and the solar irradiances lead TEC by ~1 day but they do not lead foF2. At earlier local times, the solar irradiances have a stronger correlation with foF2 than with TEC. The solar irradiances lead TEC by ~2 days and foF2 by ~1 day. The study shows that the ionospheric densities have a more significant dependence on solar soft X-ray irradiances than on F10.7.

  10. Evidence for Trends, and Lack Thereof, in Surface Solar Irradiance as Seen in Calibration-error-free Records of Cloud Shortwave Transmission for the Past Three Decades at Five Globally Diverse Sites

    NASA Astrophysics Data System (ADS)

    Dutton, E. G.

    2004-05-01

    Prior to the mid 1970's there did not exist a method of making observations of solar irradiance to an absolute accuracy better than a few percent. Until the mid 1980s, even that low level of accuracy was only achievable through extraordinary effort because commercial pyranometers are known to drift in sensitivity by up to several percent per year under some conditions. To maintain a stable measurement it is necessary to physically relate routine field measurements to international reference standards using transfer standards. Prior to the early 1980s many of these transfer standards were of less than desirable stability, especially in some countries, and while at the same time international reference standards were just undergoing development. Since the early 1990's considerable effort has gone into maintaining the absolute accuracy of ground-based solar irradiance observations. A brief review of this documented history will be presented for background along with the long-term variability in a number of surface irradiance records. To further analyze long-term observational records extending back into the period of dubious calibration pedigree, rationing or differencing methods are often utilized where the parameter of interest is the short term change in radiation, often over diurnal cycles or between periods of clear and cloudy skies. These short term changes can be expressed in percent or as the ratio of the irradiance and hence only the linearity and zero of the irradiance sensor are required to be known and not sensor's correspondence to an absolute irradiance scale. In this manner, conditions that contribute to affecting the amount of solar irradiance reaching the ground can be monitored over the long term. Using this general differencing procedure, we have examined the long-term changes in clear sky and cloudy sky irradiance relative to closely associated reference irradiances thereby having a tool to continuously monitor the solar transmission of clouds or

  11. On the effective solar zenith and azimuth angles to use with measurements of hourly irradiation

    NASA Astrophysics Data System (ADS)

    Blanc, P.; Wald, L.

    2016-02-01

    Several common practices are tested for assessing the effective solar zenith angle that can be associated to each measurement in time-series of in situ or satellite-derived measurements of hourly irradiation on horizontal surface. High quality 1 min measurements of direct irradiation collected by the BSRN stations in Carpentras in France and Payerne in Switzerland, are aggregated to yield time series of hourly direct irradiation on both horizontal and normal planes. Time series of hourly direct horizontal irradiation are reconstructed from those of hourly direct normal irradiation and estimates of the effective solar zenith angle by one of the six practices. Differences between estimated and actual time series of the direct horizontal irradiation indicate the performances of six practices. Several of them yield satisfactory estimates of the effective solar angles. The most accurate results are obtained if the effective angle is computed by two time series of the direct horizontal and normal irradiations that should be observed if the sky were cloud-free. If not possible, then the most accurate results are obtained from using irradiation at the top of atmosphere. Performances show a tendency to decrease during sunrise and sunset hours. The effective solar azimuth angle is computed from the effective solar zenith angle.

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

    NASA Astrophysics Data System (ADS)

    Deniz Goker, Umit

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  14. Solar EUV irradiance from the San Marco ASSI - A reference spectrum

    NASA Technical Reports Server (NTRS)

    Schmidtke, Gerhard; Woods, Thomas N.; Worden, John; Rottman, Gary J.; Doll, Harry; Wita, Claus; Solomon, Stanley C.

    1992-01-01

    The only satellite measurement of the solar EUV irradiance during solar cycle 22 has been obtained with the Airglow Solar Spectrometer Instrument (ASSI) aboard the San Marco 5 satellite flown in 1988. The ASSI in-flight calibration parameters are established by using the internal capabilities of ASSI and by comparing ASSI results to the results from other space-based experiments on the ASSI calibration rocket and the Solar Mesospheric Explorer (SME). A solar EUV irradiance spectrum derived from ASSI observations on November 10, 1988 is presented as a reference spectrum for moderate solar activity for the aeronomy community. This ASSI spectrum should be considered as a refinement and extension of the solar EUV spectrum published for the same day by Woods and Rottman (1990).

  15. Solar EUV irradiance from the San Marco ASSI - A reference spectrum

    NASA Astrophysics Data System (ADS)

    Schmidtke, Gerhard; Woods, Thomas N.; Worden, John; Rottman, Gary J.; Doll, Harry; Wita, Claus; Solomon, Stanley C.

    1992-11-01

    The only satellite measurement of the solar EUV irradiance during solar cycle 22 has been obtained with the Airglow Solar Spectrometer Instrument (ASSI) aboard the San Marco 5 satellite flown in 1988. The ASSI in-flight calibration parameters are established by using the internal capabilities of ASSI and by comparing ASSI results to the results from other space-based experiments on the ASSI calibration rocket and the Solar Mesospheric Explorer (SME). A solar EUV irradiance spectrum derived from ASSI observations on November 10, 1988 is presented as a reference spectrum for moderate solar activity for the aeronomy community. This ASSI spectrum should be considered as a refinement and extension of the solar EUV spectrum published for the same day by Woods and Rottman (1990).

  16. Initial Results of Aperture Area Comparisons for Exo-Atmospheric Total Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Johnson, B. Carol; Litorja, Maritoni; Fowler, Joel B.; Butler, James J.

    2009-01-01

    In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

  17. Discrepant responses of the global electron content to the solar cycle and solar rotation variations of EUV irradiance

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Le, Huijun; Zhang, Hui

    2015-05-01

    In this paper, the responses of the ionosphere to the solar cycle and solar rotation variations of extreme ultraviolet (EUV) irradiance are comparatively investigated using daily mean global electron content (GEC) and 0.1-50 nm EUV daily flux. GEC is well correlated with EUV on both the solar cycle and solar rotation timescales; however, the responses of GEC to the solar cycle and solar rotation variations of EUV are significantly different in terms of the following two aspects: (1) There is a significant time lag between the solar rotation variations of GEC and EUV; the lag is dominated by a 1-day lag and generally presents a decrease trend with solar activity decreasing. For the solar cycle variations of GEC and EUV, however, there are no evident time lags. (2) The GEC versus EUV slopes are different for the solar cycle and solar rotation variations of GEC and EUV; the solar cycle GEC versus EUV slope is higher than the solar rotation GEC versus EUV slope, and this difference occurs in different seasons and latitudinal bands. The results present an aspect of the difference between ionospheric climatology and weather.

  18. SOLAR2000 irradiances for climate change research, aeronomy and space system engineering

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent

    2004-01-01

    Improvements to spectral and temporal solar irradiances are often based upon increasingly accurate and precise measurements as well as upon better understood physics. This paper reports on one example in an emerging trend for solar irradiance models that can be characterized as hybrid irradiance modeling. Empirical and physics-based modeling of irradiances are combined and take advantage of strengths within both methods to provide a variety of solar irradiance products to science and engineering users. The SOLAR2000 (S2K) version 1.24 model (v1.24) described in this paper has gone through 17 upgrades since it was originally released in 1999 as v0.10 and now incorporates three theoretical continua, 13 rocket spectra, and time series data from five satellites using 17 instruments. S2K currently produces six integrated irradiance proxies for science and engineering applications in addition to spectrally resolved irradiances in three common wavelength formats. Integrated irradiance proxies include the E10.7 integrated EUV energy flux, QEUV total thermospheric EUV heating rate, PEUV hemispheric EUV power, T∞ exospheric temperature, RSN derived sunspot number, and S integrated spectrum. Besides three spectral wavelength and six integrated irradiance formats there are three time frames of historical, nowcast, and forecast irradiance products produced by four model grades. The Research Grade (RG) model is developed for aeronomical and climate change research, the Professional Grade (PG) model is developed for space system engineering applications, the Operational Grade (OP) model is developed for institutional and agency real-time operational space weather applications, and the System Grade (SY) model is developed for commercial operational and production applications. This report describes these model characteristics as well as the current state of operational irradiances which are now in the second release of a first generation forecast methodology. Forecast Generation

  19. Solar Spectrum (SOLSPEC) measurement from 180 to 3000 nanometers

    NASA Technical Reports Server (NTRS)

    Thuiller, G.; Simon, P. C.

    1988-01-01

    The SOLSPEC experiment, planned for the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission, is described. The purpose of this experiment is the measurement of the absolute solar irradiances in the wavelength range from 180 to 3000 nm and the variabilities of the solar irradiances in this wavelength range. Measurements of the irradiances and variabilities are used in: (1) solar-terrestrial/planetary relationships, in particular aeronomy of the stratosphere and mesosphere; (2) climatoglogy; and (3) solar physics.

  20. Determination of time-dependent uncertainty of the total solar irradiance records from 1978 to present

    NASA Astrophysics Data System (ADS)

    Fröhlich, Claus

    2016-03-01

    Aims: The existing records of total solar irradiance (TSI) since 1978 differ not only in absolute values, but also show different trends. For the study of TSI variability these records need to be combined and three composites have been devised; however, the results depend on the choice of the records and the way they are combined. A new composite should be based on all existing records with an individual qualification. It is proposed to use a time-dependent uncertainty for weighting of the individual records. Methods: The determination of the time-dependent deviation of the TSI records is performed by comparison with the square root of the sunspot number (SSN). However, this correlation is only valid for timescales of the order of a year or more because TSI and SSN react quite differently to solar activity changes on shorter timescales. Hence the results concern only periods longer than the one-year-low-pass filter used in the analysis. Results: Besides the main objective to determine an investigator-independent uncertainty, the comparison of TSI with √SSN turns out to be a powerful tool for the study of the TSI long-term changes. The correlation of √SSN with TSI replicates very well the TSI minima, especially the very low value of the recent minimum. The results of the uncertainty determination confirm not only the need for adequate corrections for degradation, but also show that a rather detailed analysis is needed. The daily average of all TSI values available on that day, weighted with the correspondingly determined uncertainty, is used to construct a "new" composite, which, overall, compares well with the Physikalisch-Meteorologisches Observatorium Davos (PMOD) composite. Finally, the TSI - √SSN comparison proves to be an important diagnostic tool not only for estimating uncertainties of observations, but also for a better understanding of the long-term variability of TSI.

  1. Compact Flyeye concentrator with improved irradiance uniformity on solar cell

    NASA Astrophysics Data System (ADS)

    Zhuang, Zhenfeng; Yu, Feihong

    2013-08-01

    A Flyeye concentrator with improved irradiance distribution on the solar cell in a concentrator photovoltaic system is proposed. This Flyeye concentrator is composed of four surfaces: a refractive surface, mirror surface, freeform surface, and transmissive surface. Based on the principles of geometrical optics, the contours of the proposed Flyeye concentrator are calculated according to Fermat's principle, the edge-ray principle, and the ray reversibility principle without solving partial differential equations or using an optimization algorithm, therefore a slope angle control method is used to construct the freeform surface. The solid model is established by applying a symmetry of revolution around the optical axis. Additionally, the optical performance for the Flyeye concentrator is simulated and analyzed by Monte-Carlo method. Results show that the Flyeye concentrator optical efficiency of >96.2% is achievable with 1333× concentration ratio and ±1.3 deg acceptance angle, and 1.3 low aspect ratio (average thickness to entry aperture diameter ratio). Moreover, comparing the Flyeye concentrator specification to that of the Köhler concentrator and the traditional Fresnel-type concentrator, results indicate that this concentrator has the advantages of improved uniformity, reduced thickness, and increased tolerance to the incident sunlight.

  2. Response of the Upper Atmosphere to Variations in the Solar Soft X-Ray Irradiance

    NASA Astrophysics Data System (ADS)

    Bailey, Scott Martin

    1995-11-01

    Terrestrial Far Ultraviolet (FUV) airglow emissions have been suggested as a means for remote sensing the structure of the upper atmosphere. The energy which leads to the excitation of FUV airglow emissions is solar irradiance at Extreme Ultraviolet (EUV) and soft x-ray wavelengths. Solar irradiance at these wavelengths is known to be highly variable; studies of Nitric Oxide (NO) in the lower thermosphere have suggested a variability of more than an order of magnitude in the solar soft x-ray irradiance. To properly interpret the FUV airglow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N _2 to infer the flux of photoelectrons in the atmosphere and thus to infer the magnitude of the solar irradiance. This dissertation presents the first simultaneous measurements of the FUV airglow, the major atmospheric constituent densities, and the solar EUV and soft x-ray irradiances. The measurements were made on three flights of an identical sounding rocket payload at different levels of solar activity. The linear response in brightness of the LBH bands to variations in solar irradiance is demonstrated. In addition to the N_2 LBH bands, atomic oxygen lines at 135.6 and 130.4 nm are also studied. Unlike the LBH bands, these emissions undergo radiative transfer effects in the atmosphere. The OI emission at 135.6 nm is found to be well modeled using a radiative transfer calculation and the known excitation processes. Unfortunately, the assumed processes leading to OI 130.4 nm excitation are found to be insufficient to reproduce the observed variability of this emission. Production of NO in the thermosphere is examined; it is shown that a lower than previously reported variability in the solar soft x-ray irradiance is required to explain the variability of NO.

  3. Solar global horizontal and direct normal irradiation maps in Spain derived from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Polo, J.

    2015-08-01

    Solar radiation derived from satellite imagery is a powerful and highly accurate technique for solar resource assessment due to its maturity and to the long term database of observation images available. This work presents the methodology developed at CIEMAT for mapping solar radiation from geostationary satellite information and it also shows solar irradiation maps of global horizontal and direct normal components elaborated for Spain. The maps presented here have been developed from daily solar irradiation estimated for eleven years of satellite images (2001-2011). An attempt to evaluate the uncertainty of the presented maps is made using ground measurements from 27 meteorological stations available in Spain for global horizontal irradiation obtained from the World Radiation Data Centre. In the case of direct normal irradiation the ground measurement database was scarce, having available only six ground stations with measurements for a period of 4 years. Yearly values of global horizontal irradiation are around 1800 kWh m-2 in most of the country and around 1950-2000 kWh m-2 for annual direct normal irradiation. Root mean square errors in monthly means were of 11% and of 29% for global horizontal and direct normal irradiation, respectively.

  4. Implications of solar irradiance variability upon long-term changes in the Earth's atmospheric temperatures

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III

    1992-01-01

    From 1979 through 1987, it is believed that variability in the incoming solar energy played a significant role in changing the Earth's climate. Using high-precision spacecraft radiometric measurements, the incoming total solar irradiance (total amount of solar power per unit area) and the Earth's mean, global atmospheric temperatures were found to vary in phase with each other. The observed irradiance and temperature changes appeared to be correlated with the 11-year cycle of solar magnetic activity. During the period from 1979 through 1985, both the irradiance and temperature decreased. From 1985 to 1987, they increased. The irradiance changed approximately 0.1 percent, while the temperature varied as much as 0.6 C. During the 1979-1987 period, the temperatures were forecasted to rise linearly because of the anthropogenic build-up of carbon dioxide and the hypothesized 'global warming', 'greenhouse effect', scenarios. Contrary to these scenarios, the temperatures were found to vary in a periodic manner in phase with the solar irradiance changes. The observed correlations between irradiance and temperature variabilily suggest that the mean, global temperature of the Earth may decline between 1990 and 1997 as solar magnetic activity decreases.

  5. Description and primary results of Total Solar Irradiance Monitor, a solar-pointing instrument on an Earth observing satellite

    NASA Astrophysics Data System (ADS)

    Wang, Hongrui; Fang, Wei; Li, Huiduan

    2015-04-01

    Solar driving mechanism for Earth climate has been a controversial problem for centuries. Long-time data of solar activity is required by the investigations of the solar driving mechanism, such as Total Solar Irradiance (TSI) record. Three Total Solar Irradiance Monitors (TSIM) have been developed by Changchun Institute of Optics, Fine Mechanics and Physics for China Meteorological Administration to maintain continuities of TSI data series which lasted for nearly 4 decades.The newest TSIM has recorded TSI daily with accurate solar pointing on the FY-3C meteorological satellite since Oct 2013. TSIM/FY-3C has a pointing system for automatic solar tracking, onboard the satellite designed mainly for Earth observing. Most payloads of FY-3C are developed for observation of land, ocean and atmosphere. Consequently, the FY-3C satellite is a nadir-pointing spacecraft with its z axis to be pointed at the center of the Earth. Previous TSIMs onboard the FY-3A and FY-3B satellites had no pointing system, solar observations were only performed when the sun swept through field-of-view of the instruments. And TSI measurements are influenced inevitably by the solar pointing errors. Corrections of the solar pointing errors were complex. The problem is now removed by TSIM/FY-3C.TSIM/FY-3C follows the sun accurately by itself using its pointing system based on scheme of visual servo control. The pointing system is consisted of a radiometer package, two motors for solar tracking, a sun sensor and etc. TSIM/FY-3C has made daily observations of TSI for more than one year, with nearly zero solar pointing errors. Short time-scale variations in TSI detected by TSIM/FY-3C are nearly the same with VIRGO/SOHO and TIM/SORCE.Instrument details, primary results of solar pointing control, solar observations and etc will be given in the presentation.

  6. Global surface solar irradiance product derived from SCIAMACHY FRESCO cloud fraction

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Stammes, Piet; Müller, Richard

    The FRESCO cloud retrieval algorithm has been developed as a simple but fast and efficient algorithm for GOME and SCIAMACHY (Koelemeijer et al., 2001; Fournier et al., 2006; Wang et al., 2008). FRESCO employs the O2 A band at 760 nm to retrieve the effective cloud fraction and cloud pressure using a simple Lambertian cloud model. The effective cloud fraction is a combination of geometric cloud fraction and cloud optical thickness, which yield the same reflectance at the top of the atmosphere as the cloud in the scene. It is well-known that clouds reduce the surface solar irradiance. Therefore the all-sky irradiance can be derived from the clear-sky irradiance with a scaling factor related to the cloud index. The cloud index is very similar to the effective cloud fraction by definition. The MAGIC (Mesoscale Atmospheric Global Irradiance Code) software converts the cloud index to the surface solar irradiance using the Heliosat method (Mueller et al. 2009). The MAGIC algorithm is also used by the CM-SAF surface solar irradiance product for clear sky cases. We applied the MAGIC software to FRESCO effective cloud fraction with slight modifications. In this presentation we will show the FRESCO-SSI monthly mean product and the comparison with the BSRN global irradiance data at Cabauw, the Netherlands and surface solar irradiance measurement at Tibetan plateau in China.

  7. Elimination of disinfection byproduct formation potential in reclaimed water during solar light irradiation.

    PubMed

    Qian-Yuan, Wu; Chao, Li; Ye, Du; Wen-Long, Wang; Huang, Huang; Hong-Ying, Hu

    2016-05-15

    Ecological storage of reclaimed water in ponds and lakes is widely applied in water reuse. During reclaimed water storage, solar light can degrade pollutants and improve water quality. This study investigated the effects of solar light irradiation on the disinfection byproduct formation potential in reclaimed water, including haloacetonitriles (HANs), trichloronitromethane (TCNM), trihalomethanes (THMs), haloketones (HKs) and chloral hydrate (CH). Natural solar light significantly decreased the formation potential of HANs, TCNM, and HKs in reclaimed water, but had a limited effect on the formation potential of THMs and CH. Ultraviolet (UV) light in solar radiation played a dominant role in the decrease of the formation potential of HANs, TCNM and HKs. Among the disinfection byproducts, the removal kinetic constant of dichloroacetonitrile (DCAN) with irradiation dose was much larger than those for dichloropropanone (1,1-DCP), trichloropropanone (1,1,1-TCP) and TCNM. During solar irradiation, fluorescence spectra intensities of reclaimed water also decreased significantly. The removal of tyrosine (Tyr)-like and tryptophan (Trp)-like protein fluorescence spectra intensity volumes was correlated to the decrease in DCAN formation potential. Solar irradiation was demonstrated to degrade Trp, Tyr and their DCAN formation potential. The photolysis products of Trp after solar irradiation were detected as kynurenine and tryptamine, which had chloroform, CH and DCAN formation potential lower than those of Trp. PMID:27010786

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  9. Interpretation of solar irradiance monitor measurements through analysis of 3D MHD simulations

    SciTech Connect

    Criscuoli, S.; Uitenbroek, H.

    2014-06-20

    Measurements from the Spectral Irradiance Monitor (SIM) on board the Solar Radiation and Climate Experiment mission indicate that solar spectral irradiance at visible and IR wavelengths varies in counter phase with the solar activity cycle. The sign of these variations is not reproduced by most of the irradiance reconstruction techniques based on variations of surface magnetism employed so far, and it is not yet clear whether SIM calibration procedures need to be improved or if instead new physical mechanisms must be invoked to explain such variations. We employ three-dimensional magnetohydrodynamic simulations of the solar photosphere to investigate the dependence of solar radiance in SIM visible and IR spectral ranges on variations of the filling factor of surface magnetic fields. We find that the contribution of magnetic features to solar radiance is strongly dependent on the location on the disk of the features, which are negative close to disk center and positive toward the limb. If features are homogeneously distributed over a region around the equator (activity belt), then their contribution to irradiance is positive with respect to the contribution of HD snapshots, but decreases with the increase of their magnetic flux for average magnetic flux larger than 50 G in at least two of the visible and IR spectral bands monitored by SIM. Under the assumption that the 50 G snapshots are representative of quiet-Sun regions, we thus find that the Spectral Irradiance can be in counter-phase with the solar magnetic activity cycle.

  10. A multi-millennial reconstruction of the total solar irradiance from the carbon radioisotope production rate

    NASA Astrophysics Data System (ADS)

    Vieira, L. A.; Krivova, N.; Solanki, S.; Balmaceda, L.

    2008-05-01

    The total solar irradiance (TSI) changes by about 0.1% between solar activity minimum and maximum. In addition to this cyclic variation, a secular variation in the irradiance is also plausible. Recent models suggest that the magnitude of the secular increase in the TSI since the Maunder Minimum was comparable to the solar cycle variation. Detailed reconstructions of irradiance since the Maunder minimum are common, but on longer timescales hardly any quantitative reconstructions are available, due to the lack of solar data. Here we present a reconstruction of solar irradiance on millennial time scales. The reconstruction involves two steps: (1) modelling of the evolution of the solar open magnetic flux from the production rate of 14C (as earlier carried out by Solanki et al. 2004 and Usoskin et al. 2007) and (2) evaluation of the solar irradiance from the calculated open magnetic flux. The model is tested by comparing to the TSI reconstruction from the sunspot number for the last 4 centuries. We also discuss limits and uncertainties of the model.

  11. Wavelength Dependence of Solar Irradiance Enhancement During X-class Flares and Its Influence on the Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    Huang, Yanshi; Richmond, A. D.

    2013-01-01

    The wavelength dependence of solar irradiance enhancement during flare events is one of the important factors in determining how the Thermosphere-Ionosphere (TI) system responds to flares. To investigate the wavelength dependence of flare enhancement, the Flare Irradiance Spectral Model (FISM) was run for 61X-class flares. The absolute and the percentage increases of solar irradiance at flare peaks, compared to pre-flare conditions, have clear wavelength dependences. The 0-4 nm irradiance increases much more ((is) approximately 680 on average) than that in the 14-25 nm waveband ((is) approximately 65 on average), except at 24 nm ( (is) approximately 220). The average percentage increases for the 25-105 nm and 122-190 nm wave bands are approximately 120 and approximately 35, respectively. The influence of 6 different wavebands (0-14 nm, 14-25 nm, 25-105 nm, 105-120 nm, 121.56 nm,and122-175 nm) on the thermosphere was examined for the October 28th, 2003 flare (X17-class) event by coupling FISM with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model(TIE-GCM) under geomagnetically quiet conditions (Kp=1). While the enhancement in the0-14nm waveband caused the largest enhancement of the globally integrated solar heating, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for the 25-105 nm waveband (EUV), which accounts for about 33 K of the total 45 K temperature enhancement, and approximately 7.4% of the total approximately 11.5% neutral density enhancement. The effect of 122-175 nm flare radiation on the thermosphere is rather small. The study also illustrates that the high-altitude thermospheric response to the flare radiation at 0-175 nm is almost a linear combination of the responses to the individual wavebands. The upper thermospheric temperature and density enhancements peaked 3-5 h after the maximum flare radiation.

  12. Wavelength Dependence of Solar Irradiance Enhancement During X-Class Flares and Its Influence on the Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Chamberlin, Phillip C.; Qian, Liying; Solomon, Stanley C.; Roble, Raymond G.; Xiao, Zuo

    2013-01-01

    The wavelength dependence of solar irradiance enhancement during flare events is one of the important factors in determining how the Thermosphere-Ionosphere (T-I) system responds to flares. To investigate the wavelength dependence of flare enhancement, the Flare Irradiance Spectral Model (FISM) was run for 61 X-class flares. The absolute and the percentage increases of solar irradiance at flare peaks, compared to pre-flare conditions, have clear wavelength dependences. The 0-14 nm irradiance increases much more (approx. 680% on average) than that in the 14-25 nm waveband (approx. 65% on average), except at 24 nm (approx. 220%). The average percentage increases for the 25-105 nm and 122-190 nm wavebands are approx. 120% and approx. 35%, respectively. The influence of 6 different wavebands (0-14 nm, 14-25 nm, 25-105 nm, 105- 120 nm, 121.56 nm, and 122-175 nm) on the thermosphere was examined for the October 28th, 2003 flare (X17-class) event by coupling FISM with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) under geomagnetically quiet conditions (Kp=1). While the enhancement in the 0-14 nm waveband caused the largest enhancement of the globally integrated solar heating, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for the 25-105 nm waveband (EUV), which accounts for about 33 K of the total 45 K temperature enhancement, and approx. 7.4% of the total approx. 11.5% neutral density enhancement. The effect of 122-175 nm flare radiation on the thermosphere is rather small. The study also illustrates that the high-altitude thermospheric response to the flare radiation at 0-175 nm is almost a linear combination of the responses to the individual wavebands. The upper thermospheric temperature and density enhancements peaked 3-5 h after the maximum flare radiation.

  13. The Total Solar Irradiance Record and Its Continuity

    NASA Astrophysics Data System (ADS)

    Willson, R. C.

    2007-12-01

    Continuous time series of total solar irradiance (TSI) observations have been constructed from the set of redundant, overlapping TSI measurements made by satellite experiments during the past 29 Years. One, the ACRIM composite [Willson & Mordvinov, 2003], displays a significant upward trend in TSI of 0.04 percent per decade during solar cycles 21-23. Another, the PMOD composite [Frohlich & Lean, 1998], displays no significant trend using different combinations of TSI data sets, computational philosophy and assumptions. The potential significance of solar variability as a climate forcing makes it important to determine which TSI composites best represents the measurement database. Two types of experiments have provided TSI satellite data: self-calibrating, precision TSI monitors and Earth radiation budget (ERB) experiments. TSI monitors provide much higher accuracy and precision and are capable of self-calibrating the degradation of their sensors, providing enhanced data traceability. The ERB experiments are designed to provide less accurate and precise TSI 'boundary value' results for ERB modeling and cannot self-calibrate sensor degradation. The optimum composite TSI time series utilizes TSI monitor results where available. However, a two year gap in the TSI monitoring record between the ACRIM1 and ACRIM2 experiments (1989 - 1991) would have prevented compilation of a continuous record over the 29 years of satellite observations were it not for the availability of ERB results during the gap. The relationship between ACRIM1 and ACRIM2 results across the ACRIM gap can be derived using the overlapping ERB data sets: the Nimbus7/ERB and/or the ERBS/ERBE. These two choices are embodied in the construction of ACRIM and PMOD composites, respectively. The ACRIM composite uses the results for its constituent databases published by the experiment science teams and relates ACRIM1 and ACRIM2 using overlapping Nimbus7/ERB comparisons. The PMOD composite uses a different subset

  14. Proton irradiation of conventional and lithium solar cells - 11-37 MeV

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Carter, J. R.

    1974-01-01

    Conventional n/p and lithium solar cells were irradiated with 11- to 37-MeV protons. The energy dependence of the solar cell degradation, calculated from electrical parameters and lifetime measurements, is shown to be very slight. Damage coefficients for the n/p cells are calculated. Annealing characteristics of both the lithium cells and the n/p cells are presented.

  15. Accurate Determination of the TOA Solar Spectral NIR Irradiance Using a Primary Standard Source and the Bouguer-Langley Technique

    NASA Astrophysics Data System (ADS)

    Bolsée, D.; Pereira, N.; Decuyper, W.; Gillotay, D.; Yu, H.; Sperfeld, P.; Pape, S.; Cuevas, E.; Redondas, A.; Hernandéz, Y.; Weber, M.

    2014-07-01

    We describe an instrument dedicated to measuring the top of atmosphere (TOA) solar spectral irradiance (SSI) in the near-infrared (NIR) between 600 nm and 2300 nm at a resolution of 10 nm. Ground-based measurements are performed through atmospheric NIR windows and the TOA SSI values are extrapolated using the Bouguer-Langley technique. The interest in this spectral range arises because it plays a main role in the Earth's radiative budget and also because it is employed to validate models used in solar physics. Moreover, some differences were observed between recent ground-based and space-based instruments that take measurements in the NIR and the reference SOLSPEC(ATLAS3) spectrum. In the 1.6 μm region, the deviations vary from 6 % to 10 %. Our measuring system named IRSPERAD has been designed by Bentham (UK) and has been radiometrically characterized and absolutely calibrated against a blackbody at the Belgian Institute for Space Aeronomy and at the Physikalisch-Technische Bundesanstalt (Germany), respectively. A four-month measurement campaign was carried out at the Izaña Atmospheric Observatory (Canary Islands, 2367 m a.s.l.). A set of top-quality solar measurements was processed to obtain the TOA SSI in the NIR windows. We obtained an average standard uncertainty of 1 % for 0.8 μm< λ<2.3 μm. At 1.6 μm, corresponding to the minimum opacity of the solar photosphere, we obtained an irradiance of 234.31±1.29 mWm-2 nm-1. Between 1.6 μm and 2.3 μm, our measurements show a disagreement varying from 6 % to 8 % relative to ATLAS3, which is not explained by the declared standard uncertainties of the two experiments.

  16. Solar irradiance change and special longitudes due to r-modes

    NASA Technical Reports Server (NTRS)

    Wolff, Charles L.; Hickey, John R.

    1987-01-01

    Sluggish global oscillations, having a periodicity of months and trapped in the sun's convection zone, modulate the amount of energy reaching earth and seem to impose some large-scale order on the distribution of solar surface features. These recently recognized oscillations (r-modes) increase the predictability of solar changes and may improve understanding of rotation and variability in other stars. Most of the 13 periodicities ranging from 13 to 85 days that are caused by r-modes can be detected in Nimbus 7 observations of solar irradiance during 3 years at solar maximum. These modes may also bear on the classical question of persistent longitudes of high solar activity.

  17. Total solar irradiance measurements by ERB/Nimbus-7 - A review of nine years

    NASA Technical Reports Server (NTRS)

    Hickey, John R.; Alton, Bradley M.; Kyle, H. Lee; Hoyt, Douglas

    1988-01-01

    The total solar irradiance measurements made by the cavity sensor of the Earth Radiation Budget experiment on the Nimbus-7 spacecraft have detected the sunspot-blocking effect, established the downward trend of the declining solar cycle, and appear to be confirming an upturn in irradiance at the outset of the new cycle. Studies of the measurements' frequency spectra have advanced the interest in helioseismology or mode analysis, and studies of photospheric activity have advanced through the modeling of the sunspot blocking and photospheric brightening vs measured irradiance.

  18. The observation of structural defects in neutron-irradiated lithium-doped silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sargent, G. A.

    1971-01-01

    Electron microscopy has been used to observe the distribution and morphology of lattice defects introduced into lithium-doped silicon solar cells by neutron irradiation. Upon etching the surface of the solar cells after irradiation, crater-like defects are observed that are thought to be associated with the space charge region around vacancy clusters. Thermal annealing experiments showed that the crater defects were stable in the temperature range 300 to 1200 K in all of the lithium-doped samples. Some annealing of the crater defects was observed to occur in the undoped cells which were irradiated at the lowest doses.

  19. Temporal Variability of Surface Solar Irradiance as a Function of Satellite-retrieved Cloud

    NASA Astrophysics Data System (ADS)

    Hinkelman, L. M.; Sengupta, M.; Habte, A.

    2014-12-01

    Studies of the impact of renewables on the electrical transmission grid are needed as power production from renewable energy resources increases. These studies require estimates of high temporal and spatial resolution power output under various scenarios. Satellite-based solar resource estimates are the best source of long-term irradiance data but are generally of lower temporal and spatial resolution than needed and thus require downscaling. Likewise, weather forecast models cannot provide high spatial or temporal irradiance predictions. Downscaling requires information about solar irradiance variability in both space and time, which is primarily a function of cloud properties. In this study, we analyze the relationships between the temporal variability of surface solar irradiance and satellite-based cloud properties. One-minute resolution surface solar irradiance data were obtained from the National Oceanic and Atmospheric Administration's Surface Radiation (SURFRAD) network. These sites are distributed across the United States to cover a range of meteorological conditions. Cloud information at a nominal 4 km resolution and half hour intervals was retrieved from NOAA's Geostationary Operation Environmental Satellites (GOES). The retrieved cloud properties were then used to select and composite irradiance data from the measurement sites in order to identify the cloud properties that exert the strongest control over short-term irradiance variability. The irradiance variability was characterized using statistics of both the irradiances themselves and of irradiance differences computed for short time scales (minutes). The relationships derived using this method will be presented, comparing and contrasting the statistics computed for the different cloud properties. The implications for downscaling irradiance from satellites or forecast models will also be discussed.

  20. Wavelength dependence of solar flare irradiance enhancement and its influence on the thermosphere-ionosphere system

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Richmond, A. D.; Deng, Y.; Qian, L.; Solomon, S. C.; Chamberlin, P. C.

    2012-12-01

    The wavelength dependence of irradiance enhancement during solar flare is one of the important factors in determining how the Thermosphere-Ionosphere (T-I) system responds to flares. To investigate the wavelength dependence of irradiance, the Flare Irradiance Spectral Model (FISM) was run for 34 X-class flares. The results show that the percentage increases of solar irradiance at flare peak have a clear wavelength dependence. In the wavelength range between 0 - 195 nm, it can vary from 1% to 10000%. The solar irradiance enhancement is largest (~1000%) in the XUV range (0 - 25 nm), and is about 100% in the EUV range (25 - 120 nm). The influence of different wavebands on the T-I system during the October 28th, 2003 flare (X17.2-class) has also been examined using the latest version of the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). While the enhancement of the globally integrated solar energy deposition is largest in the 0 - 14 nm waveband, the impact of solar irradiance enhancement on the thermosphere at 400km is largest for the 25 - 105 nm waveband. The effect of the enhancement of the 122 - 195 nm waveband is small in magnitude, but it decays slowly.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  2. A possible correlation between maxima of the far ultraviolet solar irradiance and central meridian passages of solar magnetic sector boundaries

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Wilcox, J. M.

    1974-01-01

    A description is given of the relationship observed between enhancements in the far ultraviolet solar irradiance and the position of the solar magnetic sector boundaries. The ultraviolet observations were made with the monitor of ultraviolet solar energy (MUSE) experiments which were launched aboard Nimbus 3 in April 1969 and Nimbus 4 April 1970. A comparison between the positions of solar magnetic sector boundaries and ultraviolet enchancements of the sun seems to show, at least during the year of 1969, that the ultraviolet maxima tend to occur near the times when a solar sector boundary is near the central meridian. An estimate of the magnitude of the variable ultraviolet solar energy input into the atmosphere resulting from the rotation of active solar longitudes is that for wavelengths less that 175 nm and down to H Lyman alpha it exceeds the annual variation whereas at longer wavelengths it is less. The total observed peak to peak variation in the ultraviolet irradiance from 120 to 300 nm over a solar rotation is typically at least 230 ergs/sq cm sec.

  3. Variation in spectral irradiance of the SES solar simulator

    NASA Technical Reports Server (NTRS)

    Mcnutt, A. E.

    1971-01-01

    A test to determine the spectral characteristics of the solar simulation produced by the solar environment simulator (SES) comprised a statistical analysis to determine the spectral variance, and its effect on the average absorptivity of surface coatings.

  4. Solar UV Irradiances and Associated Issues for the Atmosphere and Ionosphere

    NASA Astrophysics Data System (ADS)

    Tobiska, W.

    Several new solar proxies have been developed in the past year as the beginning of a second generation solar UV modeling and forecasting capability. These proxies help characterize the energy input into operational space physics models that provide information content on the neutral thermosphere and ionosphere. Between 1999-2000, a full solar spectrum was developed (SOLAR2000) for use in numerical atmospheric and ionospheric models relevant to climatological studies and the E10.7 index was produced for empirical thermospheric and ionospheric model applications. In 20012002, new proxies have been derived including a sunspot number, Rsn, for use by operational HF radio ray-trace algorithms and the Qeuv thermospheric heating rate for use by the aeronomy community to compare airglow-derived versus solar-derived upper atmosphere heating. The Peuv heat production term has also been developed as an index for comparing solar heating to joule heating on a global scale. The S(t) index is the integrated solar spectrum used for solar radiation pressure calculations related to spacecraft attitude control. Finally, the Tinf is the exospheric temperature that is provided for long-term climate change studies. Second generation modeling and forecasting is in development and includes higher cadence solar input information beyond daily flux values where solar flare characterization will soon become reality. The second generation forecasting is also incorporating improved algorithms ranging from wavelet transforms to solar dynamo theory in order to specify solar variability on seven time scales from nowcast and 72-hour forecast to 5 solar cycle estimation. These new proxies are derivatives of the SOLAR2000 model whose solar irradiance specification is compliant with the developing ISO draft standard WD 21348 for Determining Solar Irradiances.

  5. Experimental Benchmark for an Improved Simulation of Absolute Soft-X-Ray Emission from Polystyrene Targets Irradiated with the Nike Laser

    NASA Astrophysics Data System (ADS)

    Weaver, J. L.; Busquet, M.; Colombant, D. G.; Mostovych, A. N.; Feldman, U.; Klapisch, M.; Seely, J. F.; Brown, C.; Holland, G.

    2005-02-01

    Absolutely calibrated, time-resolved spectral intensity measurements of soft-x-ray emission (hν˜0.1 1.0 keV) from laser-irradiated polystyrene targets are compared to radiation-hydrodynamic simulations that include our new postprocessor, Virtual Spectro. This new capability allows a unified, detailed treatment of atomic physics and radiative transfer in nonlocal thermodynamic equilibrium conditions for simple spectra from low-Z materials as well as complex spectra from high-Z materials. The excellent agreement (within a factor of ˜1.5) demonstrates the powerful predictive capability of the codes for the complex conditions in the ablating plasma. A comparison to data with high spectral resolution (E/δE˜1000) emphasizes the importance of including radiation coupling in the quantitative simulation of emission spectra.

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

    USGS Publications Warehouse

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

    2000-01-01

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

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

    SciTech Connect

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

    2000-04-01

    The spectra and intensity of solar radiation (solar spectral irradiance [SSI]) was quantified in selected aquatic habitats in the vicinity of an oil field on the California coast. Solar spectral irradiance measurements consisted of spectral scans and radiometric measurements of ultraviolet (UV): UVB and UVA. Solar spectral irradiance measurements were taken at the surface and at various depths in two marsh ponds, a shallow wetland, an estuary lagoon, and the intertidal area of a high-energy sandy beach. Daily fluctuation in SSI showed a general parabolic relationship with time; maximum structure-activity relationship (SAR) was observed at approximate solar noon. Solar spectral irradiance measurements taken at 10-cm depth at approximate solar noon in multiple aquatic habitats exhibited only a twofold variation in visible light and UVA and a 4.5-fold variation in UVB. Visible light ranged from 11,000 to 19,000 {micro}W/cm{sup 2}, UVA ranged from 460 to 1,100 {micro}W/cm{sup 2}, and UVB ranged from 8.4 to 38 {micro}W/cm{sup 2}. In each habitat, the attenuation of light intensity with increasing water depth was differentially affected over specific wavelengths of SSI. The study results allowed the development of environmentally realistic light regimes necessary for photoenhanced toxicity studies.

  8. Improved radiation resistant properties of electron irradiated c-Si solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Khuram; Khan, Sohail A.; MatJafri, M. Z.

    2016-08-01

    This work investigates the radiation tolerance of c-Si solar cells under electron energy of 9 MeV with fluence of 5.09×1016 cm-2. The solar cells were fabricated and characterized before and after electron irradiation through current-voltage (I-V), capacitance-voltage (C-V), and frequency dependent conductance (Gp) measurements. The results revealed that all the output parameters such as short circuit current (Isc), open circuit voltage (Voc), series resistance (Rs), and efficiency (η) were degraded after electron irradiation. Capacitance-Voltage measurements show that there is a slight decrease in the base carrier concentration (ND), while a small increase in depletion layer width (WD) was due to an increase in the base carrier concentration. Enhancements in the density of interface states (Nss), and trap time constant (τ) have been observed after electron irradiation. The results has revealed that back surface field (BSF) solar cell with front surface passivation (FSP) presented lowest efficiency degradation ratio of 11.3% as compared to 15.3% of the solar cell without FSP. The subsequent annealing of irradiated Si solar cell devices revealed that the Si solar cell with FSP demonstrated high efficiency recovery ratio of 94% as compared to non-FSP solar cell.

  9. A I-V analysis of irradiated Gallium Arsenide solar cells

    NASA Technical Reports Server (NTRS)

    Heulenberg, A.; Maurer, R. H.; Kinnison, J. D.

    1991-01-01

    A computer program was used to analyze the illuminated I-V characteristics of four sets of gallium arsenide (GaAs) solar cells irradiated with 1-MeV electrons and 10-MeV protons. It was concluded that junction regions (J sub r) dominate nearly all GaAs cells tested, except for irradiated Mitsubishi cells, which appear to have a different doping profile. Irradiation maintains or increases the dominance by J sub r. Proton irradiation increases J sub r more than does electron irradiation. The U.S. cells were optimized for beginning of life (BOL) and the Japanese for end of life (EOL). I-V analysis indicates ways of improving both the BOL and EOL performance of GaAs solar cells.

  10. Measurement of the Total Solar Irradiance over cycle 23: results from DIARAD/VIRGO.

    NASA Astrophysics Data System (ADS)

    Dewitte, S.; Mekaoui, S.; Crommelynck, D.

    2007-12-01

    The Total Solar Irradiance (TSI) is measured from space since 29 years, covering 2.6 11 year solar cycles. Over the last 12 years, covering solar cycle 23, TSI measurements are available from the VIRGO experiment on the SOHO satellite. SOHO is located at the L1 Lagrange point, offering continuous sun observation and a stable thermal environment. VIRGO contains two independent radiometers, DIARAD and PMO, each with their own ageing monitoring capabilities. From these two radiometers, DIARAD is the only one with a nominal operation over the entire mission, and DIARAD has the lowest ageing. We present the ageing correction of DIARAD and PMO by the DIARAD team, and discuss the differences with the versions available from the PMO team. In addition to the normal exposure dependent ageing corrections applied by both the DIARAD and PMO teams, the PMO team applies additional 'exposure independent corrections' or 'sensitivity changes' which create an artificial downward trend of about 0.4 W/m2 for both DIARAD and PMO. Besides the two independent measurements of the TSI variation over cycle 23 from DIARAD and PMO, two more independent measurements over the complete cycle are available, on the one hand from a combination of ACRIM 2 and ACRIM 3, on the other hand from a combination of ERBS and TIM. All together, these measurements allow to measure the decadal trend of the TSI variation over cycle 23 with an unprecedented accuracy. All instruments show a similar long term behaviour except ACRIM 3 which shows a faster decline. We construct a composite time series using DIARAD/VIRGO as a reference instrument to put all instruments at the same absolute level. From the composite time series we can conclude there is no significant decadal trend during cycle 23. This is in contradiction with the ACRIM composite which shows a decreasing trend due to the ACRIM 3 decline, and with the PMO composite which shows a decreasing trend due to the 'exposure independent corrections' applied to

  11. Photocatalytic oxidation of pesticides by solar-irradiated TiO[sub 2] systems

    SciTech Connect

    Sullivan, J.M.; Grinstead, J.H. Jr.

    1992-01-01

    Research at the Tennessee Valley Authority's National Fertilizer and Environmental Research Center has been directed toward the development of passive basin type solar evaporators as a simple means of reducing the volume of fertilizer and pesticide contaminated rinsewater generated at fertilizer and agrichemical dealerships. In conjunction with this work, investigations are also devoted to TiO[sub 2] catalyzed solar photooxidation as a potential procedure for destroying pesticides in dilute aqueous systems. Initial tests in which dilute samples of the herbicides; Bicep (atrazine and metolachlor), Lasso (alachlor), and Sencor (metribuzin); were recirculated continuously over TiO[sub 2] impregnated fiberglass gauze, under solar irradiation, gave promising results. In the case of metribuzin, solar irradiation induced oxidation appeared effective at concentrations as high as 600 ppM. Catalytic efficiency did not appear greatly affected by using tap water rather than distilled water to dilute the pesticides. Two solar reactor designs will be discussed.

  12. Photocatalytic oxidation of pesticides by solar-irradiated TiO{sub 2} systems

    SciTech Connect

    Sullivan, J.M.; Grinstead, J.H. Jr.

    1992-12-01

    Research at the Tennessee Valley Authority`s National Fertilizer and Environmental Research Center has been directed toward the development of passive basin type solar evaporators as a simple means of reducing the volume of fertilizer and pesticide contaminated rinsewater generated at fertilizer and agrichemical dealerships. In conjunction with this work, investigations are also devoted to TiO{sub 2} catalyzed solar photooxidation as a potential procedure for destroying pesticides in dilute aqueous systems. Initial tests in which dilute samples of the herbicides; Bicep (atrazine and metolachlor), Lasso (alachlor), and Sencor (metribuzin); were recirculated continuously over TiO{sub 2} impregnated fiberglass gauze, under solar irradiation, gave promising results. In the case of metribuzin, solar irradiation induced oxidation appeared effective at concentrations as high as 600 ppM. Catalytic efficiency did not appear greatly affected by using tap water rather than distilled water to dilute the pesticides. Two solar reactor designs will be discussed.

  13. High-resolution solar spectral irradiance from extreme ultraviolet to far infrared

    NASA Astrophysics Data System (ADS)

    Fontenla, J. M.; Harder, J.; Livingston, W.; Snow, M.; Woods, T.

    2011-10-01

    This paper presents new extremely high-resolution solar spectral irradiance (SSI) calculations covering wavelengths from 0.12 nm to 100 micron obtained by the Solar Irradiance Physical Modeling (SRPM) system. Daily solar irradiance spectra were constructed for most of Solar Cycle 23 based on a set of physical models of the solar features and non-LTE calculations of their emitted spectra as function of viewing angle, and solar images specifying the distribution of features on the solar disk. Various observational tests are used to assess the quality of the spectra provided here. The present work emphasizes the effects on the SSI of the upper chromosphere and full-non-LTE radiative transfer calculation of level populations and ionizations that are essential for physically consistent results at UV wavelengths and for deep lines in the visible and IR. This paper also considers the photodissociation continuum opacity of molecular species, e.g., CH and OH, and proposes the consideration of NH photodissociation which can solve the puzzle of the missing near-UV opacity in the spectral range of the near-UV. Finally, this paper is based on physical models of the solar atmosphere and extends the previous lower-layer models into the upper-transition-region and coronal layers that are the dominant source of photons at wavelengths shorter than ˜50 nm (except for the He II 30.4 nm line, mainly formed in the lower-transition-region).

  14. A method for estimating direct normal solar irradiation from satellite data for a tropical environment

    SciTech Connect

    Janjai, Serm

    2010-09-15

    In order to investigate a potential use of concentrating solar power technologies and select an optimum site for these technologies, it is necessary to obtain information on the geographical distribution of direct normal solar irradiation over an area of interest. In this work, we have developed a method for estimating direct normal irradiation from satellite data for a tropical environment. The method starts with the estimation of global irradiation on a horizontal surface from MTSAT-1R satellite data and other ground-based ancillary data. Then a satellite-based diffuse fraction model was developed and used to estimate the diffuse component of the satellite-derived global irradiation. Based on this estimated global and diffuse irradiation and the solar radiation incident angle, the direct normal irradiation was finally calculated. To evaluate its performance, the method was used to estimate the monthly average hourly direct normal irradiation at seven pyrheliometer stations in Thailand. It was found that values of monthly average hourly direct normal irradiation from the measurements and those estimated from the proposed method are in reasonable agreement, with a root mean square difference of 16% and a mean bias of -1.6%, with respect to mean measured values. After the validation, this method was used to estimate the monthly average hourly direct normal irradiation over Thailand by using MTSAT-1R satellite data for the period from June 2005 to December 2008. Results from the calculation were displayed as hourly and yearly irradiation maps. These maps reveal that the direct normal irradiation in Thailand was strongly affected by the tropical monsoons and local topography of the country. (author)

  15. Forecasting solar irradiation using WRF model and refining statistics for Northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Pereira, E. B.; Lima, F. J. L.; Martins, F. R.

    2015-12-01

    Solar energy is referred to as variable generation sources because their electricity production varies based on the availability of sun irradiance. To accommodate this variability, electricity grid operators use a variety of tools to maintain a reliable electricity supply, one of them is to forecast solar irradiation, and to adjust other electricity sources as needed. This work reports an approach to forecast solar irradiation in the Brazilian Northeastern region (NEB) by using statistically post-processing data from mesoscale model outputs. The method assimilates the diversity of climate characteristics occurring in the region presenting the largest solar energy potentials in Brazil. Untreated solar irradiance forecasts for 24h in advance were obtained using the WRF model runs. Cluster analysis technique was employed to find out areas presenting similar climate characteristics and to reduce uncertainties. Comparison analysis between WRF model outputs and site-specific measured data were performed to evaluate the model skill in forecasting the surface solar irradiation. After that, post-processing of WRF outputs using artificial neural networks (ANNs) and multiple regression methods refined the short-term solar irradiation forecasts. A set of pre-selected variables of the WRF model outputs representing the forecasted atmospheric conditions were used as predictors by the ANNs. Several predictors were tested in the adjustment and simulation of the ANNs. We found the best ANNs architecture and a group of 10 predictors, with which more in-depth analyzes were carried out, including performance evaluation for fall and spring of 2011 (rainy and dry season in NEB). The site-specific measured solar radiation data came from 110 stations distributed throughout the NEB. Data for the rainy season were acquired from March to May, and for the dry season from September to November. We concluded that the untreated numerical forecasts of solar irradiation provided by WRF exhibited a

  16. Estimation of daily global solar irradiation under different sky conditions in central and southern Iran

    NASA Astrophysics Data System (ADS)

    Didari, Shohreh; Zand-Parsa, Shahrokh

    2015-10-01

    Daily global solar irradiation (R s) is one of the main inputs in environmental modeling. Because of the lack of its measuring facilities, high-quality and long-term data are limited. In this research, R s values were estimated based on measured sunshine duration and cloud cover of our synoptic meteorological stations in central and southern Iran during 2008, 2009, and 2011. Clear sky solar irradiation was estimated from linear regression using extraterrestrial solar irradiation as the independent variable with normalized root mean square error (NRMSE) of 4.69 %. Daily R s was calibrated using measured sunshine duration and cloud cover data under different sky conditions during 2008 and 2009. The 2011 data were used for model validation. According to the results, in the presence of clouds, the R s model using sunshine duration data was more accurate when compared with the model using cloud cover data (NRMSE = 11. 69 %). In both models, with increasing sky cloudiness, the accuracy decreased. In the study region, more than 92 % of sunshine durations were clear or partly cloudy, which received close to 95 % of total solar irradiation. Hence, it was possible to estimate solar irradiation with a good accuracy in most days with the measurements of sunshine duration.

  17. A measurement of the quiet network contribution to solar irradiance variation

    NASA Astrophysics Data System (ADS)

    Foukal, Peter; Milano, Leo

    A large increase in quiet network area since the 17th century Maunder Minimum has been suggested as a mechanism for increasing solar irradiance sufficiently to drive global warming. We show that this mechanism requires essentially complete disappearance of network proceeding back in time to the beginning of the 20th century. This disappearance is ruled out by the many Ca K spectroheliograms taken since the discovery of the network in the early 1890's. Furthermore, network area measurements we have carried out on Ca K spectroheliograms digitized from the Mt. Wilson and NSO/Sacramento Peak archives, for the nine solar activity minima between 1914 and 1996, show no evidence of network area variations large enough to produce a significant long-term component of total irradiance variation. A network brightness variation of sufficient magnitude is also unlikely, given the linear dependence of solar microwave flux on area of bright structures.More generally, recent analyses of cycle 21,22 pyrheliometry, and of broadband stellar photometry, provide little support for any long-term irradiance component These results do not rule out a secular irradiance increase. But they suggest that high climate sensitivity to the relatively small changes in solar total and UV irradiance that have been observed, provides a more likely explanation of the global temperature-solar activity correlation.

  18. Determination of critical assembly absolute power using post-irradiation activation measurement of week-lived fission products.

    PubMed

    Košťál, Michal; Švadlenková, Marie; Milčák, Ján; Rypar, Vojtěch; Koleška, Michal

    2014-07-01

    The work presents a detailed comparison of calculated and experimentally determined net peak areas of longer-living fission products after 100 h irradiation on a reactor with power of ~630 W and several days cooling. Specifically the nuclides studied are (140)Ba, (103)Ru, (131)I, (141)Ce, (95)Zr. The good agreement between the calculated and measured net peak areas, which is better than in determination using short lived (92)Sr, is reported. The experiment was conducted on the VVER-1000 mock-up installed on the LR-0 reactor. The Monte Carlo approach has been used for calculations. The influence of different data libraries on results of calculation is discussed as well. PMID:24566373

  19. Segmentation of coronal features to understand the solar EUV and UV irradiance variability

    NASA Astrophysics Data System (ADS)

    Kumara, S. T.; Kariyappa, R.; Zender, J. J.; Giono, G.; Delouille, V.; Chitta, L. P.; Damé, L.; Hochedez, J.-F.; Verbeeck, C.; Mampaey, B.; Doddamani, V. H.

    2014-01-01

    Context. The study of solar irradiance variability is of great importance in heliophysics, the Earth's climate, and space weather applications. These studies require careful identifying, tracking and monitoring of active regions (ARs), coronal holes (CHs), and the quiet Sun (QS). Aims: We studied the variability of solar irradiance for a period of two years (January 2011-December 2012) using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Methods: We used the spatial possibilistic clustering algorithm (SPoCA) to identify and segment coronal features from the EUV observations of AIA. The AIA segmentation maps were then applied on SWAP images, and parameters such as the intensity, fractional area, and contribution of ARs/CHs/QS features were computed and compared with the full-disk integrated intensity and LYRA irradiance measurements. Results: We report the results obtained from SDO/AIA and PROBA2/SWAP images taken from January 2011 to December 2012 and compare the resulting integrated full-disk intensity with PROBA2/LYRA irradiance. We determine the contributions of the segmented features to EUV and UV irradiance variations. The variations of the parameters resulting from the segmentation, namely the area, integrated intensity, and relative contribution to the solar irradiance, are compared with LYRA irradiance. We find that the active regions have a great impact on the irradiance fluctuations. In the EUV passbands considered in this study, the QS is the greatest contributor to the solar irradiance, with up to 63% of total intensity values. Active regions, on the other hand, contribute to about 10%, and off-limb structures to about 24%. We also find that the area of the features is highly variable suggesting that their area has to be taken into account in irradiance models, in addition to their intensity variations

  20. Influence of spatiotemporally distributed irradiance data input on temperature evolution in parabolic trough solar field simulations

    NASA Astrophysics Data System (ADS)

    Bubolz, K.; Schenk, H.; Hirsch, T.

    2016-05-01

    Concentrating solar field operation is affected by shadowing through cloud movement. For line focusing systems the impact of varying irradiance has been studied before by several authors with simulations of relevant thermodynamics assuming spatially homogeneous irradiance or using artificial test signals. While today's simulation capabilities allow more and more a higher spatiotemporal resolution of plant processes there are only few studies on influence of spatially distributed irradiance due to lack of available data. Based on recent work on generating real irradiance maps with high spatial resolution this paper demonstrates their influence on solar field thermodynamics. For a case study an irradiance time series is chosen. One solar field section with several loops and collecting header is modeled for simulation purpose of parabolic trough collectors and oil as heat transfer medium. Assuming homogeneous mass flow distribution among all loops we observe spatially varying temperature characteristics. They are analysed without and with mass flow control and their impact on solar field control design is discussed. Finally, the potential of distributed irradiance data is outlined.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Solar Irradiance Reference Spectra (SIRS) for the 2008 Whole Heliosphere Interval (WHI)

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Chamberlin, Phillip C.; Harder, Jerald W.; Hock, Rachel A.; Snow, Martin; Eparvier, Francis G.; Fontenla, Juan; McClintock, William E.; Richard, Erik C.

    2009-01-01

    The IHY2007 Whole Heliosphere Interval (WHI) for solar Carrington Rotation 2068 (20 March to 16 April 2008) has been very successful in obtaining a wide variety of solar, heliospheric, and planetary observations during times of solar cycle minimum conditions. One of these efforts is the generation of solar irradiance reference spectra (SIRS) from 0.1 nm to 2400 nm using a combination of satellite and sounding rocket observations. These reference spectra include daily satellite observations from TIMED Solar Extreme ultraviolet Experiment (SEE) and Solar Radiation and Climate Experiment (SORCE) instruments. The extreme ultraviolet range is also improved with higher spectral resolution observations using the prototype SDO Extreme ultraviolet Variability Experiment (EVE) aboard a sounding rocket launched on 14 April 2008. The SIRS result is an important accomplishment in that it is the first data set to have simultaneous measurements over the full spectral coverage up to 2400 nm during solar cycle minimum conditions.

  3. Temporal and spectral variations of the photoelectron flux and solar irradiance during an X class solar flare

    NASA Astrophysics Data System (ADS)

    Peterson, W. K.; Chamberlin, P. C.; Woods, T. N.; Richards, P. G.

    2008-06-01

    Photoelectrons are the main energy source of airglow used to diagnose the state of the ionosphere-thermosphere system. Because of measurement uncertainties and substantial gaps in the historical record, parameterized models of the EUV irradiance and photoelectron flux are generally used to estimate airglow intensities. This paper compares observed and modeled photoelectron spectra from an X3 class flare that occurred on July 15, 2002. The photoelectron data were obtained from the FAST satellite. Model photoelectron spectra were obtained from the Field Line Inter-hemispheric Plasma (FLIP) model using 10 s cadence solar spectra at 1 nm resolution from the Flare Irradiance Spectral Model (FISM). The observed and modeled spectra agree well temporally and spectrally within the uncertainties of the models and data. Systematic differences found between observed and modeled photoelectron spectra suggest that the solar irradiance from FISM could be improved at wavelengths shortward of 17 nm.

  4. Wavelength Dependence of Solar Flare Irradiation and its Influence on the Thermosphere

    NASA Technical Reports Server (NTRS)

    Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Qian, L.; Solomon, S.; Chamberlin, P.

    2012-01-01

    The wavelength dependence of solar flare enhancement is one of the important factors determining how the Thermosphere-Ionosphere (T-I) system response to flares. To investigate the wavelength dependence of solar flare, the Flare Irradiance Spectral Model (FISM) has been run for 34 X-class flares. The results show that the percentage increases of solar irradiance at flare peak comparing to pre-flare condition have a clear wavelength dependence. In the wavelength range between 0 - 195 nm, it can vary from 1% to 10000%. The solar irradiance enhancement is largest ( 1000%) in the XUV range (0 - 25 nm), and is about 100% in EUV range (25 - 120 nm). The influence of different wavebands on the T-I system during the October 28th, 2003 flare (X17.2-class) has also been examined using the latest version of National Center for Atmospheric Research (NCAR) Thermosphere- Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). While the globally integrated solar energy deposition is largest in the 0 - 14 nm waveband, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for 25 - 105 nm waveband. The effect of 122 - 195 nm is small in magnitude, but it decays slowly.

  5. Solar simulated irradiation modulates gene expression and activity of antioxidant enzymes in cultured human dermal fibroblasts.

    PubMed

    Leccia, M T; Yaar, M; Allen, N; Gleason, M; Gilchrest, B A

    2001-08-01

    Exposure of skin to solar irradiation generates reactive oxygen species that damage DNA, membranes, mitochondria and proteins. To protect against such damage, skin cells have evolved antioxidant enzymes including glutathione peroxidase (GSH-Px), copper and zinc-dependent superoxide dismutase (SOD1), the mitochondrial manganese-dependent superoxide dismutase (SOD2), and catalase. This report examines the effect of a single low or moderate dose exposure to solar-simulating combined UVB and UVA irradiation on the gene expression and activities of these antioxidant enzymes in cultured normal human fibroblasts. We find that both doses initially decrease GSH-Px, SOD2 and catalase activities, but within 5 days after irradiation the activities of the enzymes return to pre-irradiation level (catalase) or are induced slightly (SOD1, GSH-Px) or substantially (SOD2) above the basal level. For SOD1, SOD2 and catalase, the higher dose also detectably modulates the mRNA level of these enzymes. Our results indicate that the effects of a single physiologic solar simulated irradiation dose persist for at least several days and suggest that skin cells prepare for subsequent exposure to damaging irradiation by upregulating this antioxidant defense system, in particular the mitochondrial SOD2. Our findings are consistent with the existence of a broad-based SOS-like response in irradiated human skin. PMID:11493316

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

    Fat'yanov, O V; Asimow, P D

    2015-10-01

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

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

    SciTech Connect

    Fat’yanov, O. V. Asimow, P. D.

    2015-10-15

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

  9. The origin of Total Solar Irradiance variability on timescales less than a day

    NASA Astrophysics Data System (ADS)

    Shapiro, Alexander; Krivova, Natalie; Schmutz, Werner; Solanki, Sami K.; Leng Yeo, Kok; Cameron, Robert; Beeck, Benjamin

    2016-07-01

    Total Solar Irradiance (TSI) varies on timescales from minutes to decades. It is generally accepted that variability on timescales of a day and longer is dominated by solar surface magnetic fields. For shorter time scales, several additional sources of variability have been proposed, including convection and oscillation. However, available simplified and highly parameterised models could not accurately explain the observed variability in high-cadence TSI records. We employed the high-cadence solar imagery from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and the SATIRE (Spectral And Total Irradiance Reconstruction) model of solar irradiance variability to recreate the magnetic component of TSI variability. The recent 3D simulations of solar near-surface convection with MURAM code have been used to calculate the TSI variability caused by convection. This allowed us to determine the threshold timescale between TSI variability caused by the magnetic field and convection. Our model successfully replicates the TSI measurements by the PICARD/PREMOS radiometer which span the period of July 2010 to February 2014 at 2-minute cadence. Hence, we demonstrate that solar magnetism and convection can account for TSI variability at all timescale it has ever been measured (sans the 5-minute component from p-modes).

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  12. A technique for global monitoring of net solar irradiance at the ocean surface. II - Validation

    NASA Technical Reports Server (NTRS)

    Chertock, Beth; Frouin, Robert; Gautier, Catherine

    1992-01-01

    The generation and validation of the first satellite-based long-term record of surface solar irradiance over the global oceans are addressed. The record is generated using Nimbus-7 earth radiation budget (ERB) wide-field-of-view plentary-albedo data as input to a numerical algorithm designed and implemented based on radiative transfer theory. The mean monthly values of net surface solar irradiance are computed on a 9-deg latitude-longitude spatial grid for November 1978-October 1985. The new data set is validated in comparisons with short-term, regional, high-resolution, satellite-based records. The ERB-based values of net surface solar irradiance are compared with corresponding values based on radiance measurements taken by the Visible-Infrared Spin Scan Radiometer aboard GOES series satellites. Errors in the new data set are estimated to lie between 10 and 20 W/sq m on monthly time scales.

  13. Simulation Study of Effects of Solar Irradiance and Sea Surface Temperature on Monsoons and Global Circulation

    NASA Technical Reports Server (NTRS)

    Sud, Y. C.; Walker, G. K.; Mehta, V.; Lau, W. K.-M.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A recent version of the GEOS 2 GCM was used to isolate the roles of the annual cycles of solar irradiation and/or sea-surface temperatures (SSTs) on the simulated circulation and rainfall. Four 4-year long integrations were generated with the GCM. The first integration, called Control Case, used daily-interpolated SSTs from a 30 year monthly SST climatology that was obtained from the analyzed SST-data, while the solar irradiation at the top of the atmosphere was calculated normally at hourly intervals. The next two cases prescribed the SSTs or the incoming solar irradiance at the top of the atmosphere at their annual mean values, respectively while everything else was kept the same as in the Control Case. In this way the influence of the annual cycles of both external forcings was isolated.

  14. Distribution of solar irradiance on inclined surfaces caused by moving clouds

    NASA Astrophysics Data System (ADS)

    Tomson, Teolan

    2016-05-01

    The distribution of solar irradiance in shadows of discrete (broken) clouds differs from the distribution calculated for inclined surfaces on the basis of traditional transposition models and changes fast. This phenomenon is studied in this paper. For calculations of dynamic distributions of irradiance on inclined surfaces, a formal point source of direct radiation near the real position of the sun is defined as the source of the "imaginable radiation." This notion is used to create a one-dimensional (1D) simulation model, which allows the fast-changing distribution of irradiance to be calculated. In general, the coincidence of calculated and measured irradiance on inclined surfaces is good. The paper also shows how the current value of the diffuse component of solar radiation can be derived from measurements of total radiation in four differently tilted planes.

  15. The spectral irradiance of some solar simulators and its effect on cell measurements

    SciTech Connect

    Seaman, C.H.; Anspaugh, B.E.; Downing, R.G.; Estey, R.S.

    1980-01-01

    Moderate resolution spectral irradiance measurements in the range 300 nm to 1100 nm have been made of eight radiant sources which are currently being used as solar simulators. Spectral irradiance data are presented in graphical form. To demonstrate the interplay of source spectral distribution and cell spectral response, measurements of short circuit current of five cells of differing response characteristics have been made with these sources. These results are presented in tabular and graphical form.

  16. A Comparison of Variable Total and Ultraviolet Solar Irradiance Inputs to 20 th Century Global Warming

    NASA Astrophysics Data System (ADS)

    Foukal, P. V.

    2002-05-01

    Analysis of spaceborne radiometry has shown that the total solar irradiance variation over the past two activity cycles was approximately proportional to the weighted difference between areas of dark spots and bright faculae and enhanced network. Empirical models of ultraviolet irradiance variation indicate that its behavior is dominated by changes in area of the bright component alone, whose photometric contrast increases at shorter wavelength.This difference in time behavior of total and UV irradiances could help to discriminate between their relative importance in forcing of global warming. Our recent digitization of archival Ca K images from Mt Wilson and NSO provides the first direct measurement of variations in area of the bright component, extending between 1915 and 1999 (previous models have relied on the sunspot number or other proxies to estimate the bright - component contribution). We use these more direct measurements to derive the time behavior of solar total and UV irradiance variation, over this period .We find that they are significantly different;the total irradiance variation accounts for over 80 percent of the variance in global temperature during this period, while the ultraviolet irradiance variation accounts for only about 20 percent. The amplitude of total irradiance variation in our model is smaller than required to influence global warming,in current climate models.Also, the impact of sulfate aerosol variations on the extended cooling between the 1940's and 1970's must be better understood before the significance of correlations between 20 th century global warming, and any solar activity index can be properly assessed. Despite these caveats, the lower correlation we find between global temperature and UV,compared to total, irradiance requires consideration in the search for physical mechanisms linking solar activity and climate. This work was supported in part under NASA grant NAG5-7607 to CRI, Inc., and NAG5-10998 to the Applied Physics

  17. Solar irradiance observed at Summit, Greenland: Possible links to magnetic activity on short timescales

    NASA Astrophysics Data System (ADS)

    Frederick, John E.

    2016-09-01

    Measurements of ground-level visible sunlight (400-600 nm) from Summit, Greenland over the period August 2004 through October 2014 define the attenuation provided by cloudiness, including its dependence on solar elevation and season. The long-term mean cloud-attenuation increases with increasing solar zenith angle, consistent with radiative transfer calculations which treat a cloud as a plane parallel layer with a strong bias toward forward scattering and an albedo for diffuse radiation near 0.1. The ratio of measured irradiance to clear-sky irradiance for solar zenith angles greater than 66° has a small, but statistically significant, positive correlation with the previous day's magnetic activity as measured by the daily Ap index, but no clear relationship exists between the irradiance ratio and daily changes in the ground-level neutron flux measured at Thule over the time frame considered. A high value of Ap on one day tends to be followed by a day whose ground-level solar irradiance is slightly greater than would occur otherwise. In an average sense, the visible irradiance following a day with Ap>16 exceeds that following a day with Ap≤16 by 1.2-1.3% with a 95% confidence range of approximately ±1.0%. The results are broadly compatible with small changes in atmospheric scattering following magnetic disturbances.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  19. Solar irradiance from Nimbus-7 compared with ground-based photometry

    NASA Technical Reports Server (NTRS)

    Chapman, G. A.; Cookson, A. M.; Hoyt, D. V.

    1994-01-01

    We have compared total solar irradiance from Nimbus-7 with ground-based photometry from the San Fernando Observatory (SFO) for 109 days between 1 June and 31 December, 1988. We have also included in some analyses NOAA-9 SBUV2 data or F10.7 radio flux. The Nimbus-7 data are from orbital samples, averaged to the mean time of observation at SFO. Using the same parameters as in Chapman et al. (1992), the multiple regression gives an R(exp 2) = 0.9131 and a 'solar minimum' irradiance, S(sub 0) = 1371.76 +/- 0.18 W/sq m for the best fit.

  20. Solar irradiance in the stratosphere - Implications for the Herzberg continuum absorption of O2

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Mentall, J. E.

    1982-01-01

    A set of solar irradiance observations is analyzed that were performed from the third Solar Absorption Balloon Experiment (SABE-3) as the payload ascended through the stratosphere from 32 to 39 km. Comparison of these data with calculations of the attenuated irradiance based on simultaneous ozone and pressure measurements made from the payload suggests a refinement of the cross section values used in photochemical models. More ultraviolet radiation in the 200-210 nm spectral region reaches the middle stratosphere than is predicted by the absorption data presently available. It is suggested that significantly smaller values for the Herzberg continuum of O2 be used in future models.

  1. Towards the automatic identification of cloudiness condition by means of solar global irradiance measurements

    NASA Astrophysics Data System (ADS)

    Sanchez, G.; Serrano, A.; Cancillo, M. L.

    2010-09-01

    This study focuses on the design of an automatic algorithm for classification of the cloudiness condition based only on global irradiance measurements. Clouds are a major modulating factor for the Earth radiation budget. They attenuate the solar radiation and control the terrestrial radiation participating in the energy balance. Generally, cloudiness is a limiting factor for the solar radiation reaching the ground, highly contributing to the Earth albedo. Additionally it is the main responsible for the high variability shown by the downward irradiance measured at ground level. Being a major source for the attenuation and high-frequency variability of the solar radiation available for energy purposes in solar power plants, the characterization of the cloudiness condition is of great interest. This importance is even higher in Southern Europe, where very high irradiation values are reached during long periods within the year. Thus, several indexes have been proposed in the literature for the characterization of the cloudiness condition of the sky. Among these indexes, those exclusively involving global irradiance are of special interest since this variable is the most widely available measurement in most radiometric stations. Taking this into account, this study proposes an automatic algorithm for classifying the cloudiness condition of the sky into three categories: cloud-free, partially cloudy and overcast. For that aim, solar global irradiance was measured by Kipp&Zonen CMP11 pyranometer installed on the terrace of the Physics building in the Campus of Badajoz (Spain) of the University of Extremadura. Measurements were recorded at one-minute basis for a period of study extending from 23 November 2009 to 31 March 2010. The algorithm is based on the clearness index kt, which is calculated as the ratio between the solar global downward irradiance measured at ground and the solar downward irradiance at the top of the atmosphere. Since partially cloudy conditions

  2. The solar ultraviolet spectral irradiance monitor (SUSIM) experiment on board the Upper Atmosphere Research Satellite (UARS)

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.; Edlow, K. L.; Floyd, L. E., IV; Lean, J. L.; Vanhoosier, M. E.

    1993-01-01

    The state of solar ultraviolet irradiance measurements in 1978, when NASA requested proposals for a new generation of solar ultraviolet monitors to be flown on the Upper Atmosphere Research Satellite (UARS), is described. To overcome the radiometric uncertainties that plagued the measurements at this time, the solar ultraviolet spectral irradiance monitor (SUSIM) instrument design included in-flight calibration light sources and multichannel photometers. Both are aimed at achieving a maximum precision of the SUSIM measurements over a long period of time, e.g., one solar cycle. The design of the SUSIM-UARS instrument is compared with the original design specifications for the UARS instruments. Details including optical train, filters, detectors, and contamination precautions are described. Also discussed are the SUSIM-UARS preflight calibration and characterization, as well as the results of the inflight performance of the instrument during the first 3 months of operation. Finally, flight operations, observation strategy, and data reduction schemes are outlined.

  3. A comparison of solar irradiances measured by SBUV, SME, and rockets

    NASA Technical Reports Server (NTRS)

    Schlesinger, Barry M.; Heath, Donald F.

    1988-01-01

    In this paper, Solar Backscatter Ultraviolet (SBUV) measurements of solar irradiance and predictions from the Mg 280-nm index are compared with each other and with coincident Solar Mesosphere Explorer (SME) and rocket measurements. The SBUV irradiances show a systematic decrease with time not seen in the rocket measurements; a correction for this decrease is introduced. The scatter and overall structure in the SME spectra is 3-5 percent, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1 percent. Such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the sun.

  4. A Preliminary Analysis of Solar Irradiance Measurements at TNB Solar Research Centre for Optimal Orientation of Fixed Solar Panels installed in Selangor Malaysia

    NASA Astrophysics Data System (ADS)

    Hashim, A. M.; Ali, M. A. M.; Ahmad, B.; Shafie, R. M.; Rusli, R.; Aziz, M. A.; Hassan, J.; Wanik, M. Z. C.

    2013-06-01

    The well established rule for orienting fixed solar devices is to face south for places in the northern hemisphere and northwards for the southern hemisphere. However for regions near the equator such as in Selangor Malaysia, the position of the sun at solar noon is always near zenith both to the north and south depending on location and month of year. This paper reports an analysis of global solar radiation data taken at TNB Solar Research Centre, Malaysia. The solar radiation is measured using both shaded and exposed pyranometers together with a pyrheliometer which is mounted on a sun-tracker. The analysis on the solar measurements show that a near regular solar irradiation pattern had occurred often enough during the year to recommend an optimum azimuth orientation of installing the fixed solar panels tilted facing towards east. Even though all the solar measurements were done at a single location in TNBR Solar Research Centre at Bangi, for locations near the equator with similar weather pattern, the recommended azimuth direction of installing fixed solar panels and collectors tilted eastward will also be generally valid.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  6. In Search of Sun-Climate Connection Using Solar Irradiance Measurements and Climate Records

    NASA Technical Reports Server (NTRS)

    Kiang, Richard K.; Kyle, H. Lee

    2000-01-01

    The Earth's temperature has risen approximately 0.5 degree-C in the last 150 years. Because the atmospheric concentration of carbon dioxide has increased nearly 30% since the industrial revolution, a common conjecture, supported by various climate models, is that anthropogenic greenhouse gases have contributed to global warming. Another probable factor for the warming is the natural variation of solar irradiance. Although the variation is as small as 0.1 % it is hypothesized that it contributes to part of the temperature rise. Warmer or cooler ocean temperature at one part of the Globe may manifest as abnormally wet or dry weather patterns some months or years later at another part of the globe. Furthermore, the lower atmosphere can be affected through its coupling with the stratosphere, after the stratospheric ozone absorbs the ultraviolet portion of the solar irradiance. In this paper, we use wavelet transforms based on Morlet wavelet to analyze the time-frequency properties in several datasets, including the Radiation Budget measurements, the long-term total solar irradiance time series, the long-term temperature at two locations for the North and the South Hemisphere. The main solar cycle, approximately 11 years, are identified in the long-term total solar irradiance time series. The wavelet transform of the temperature datasets show annual cycle but not the solar cycle. Some correlation is seen between the length of the solar cycle extracted from the wavelet transform and the North Hemisphere temperature time series. The absence of the 11-year cycle in a time series does not necessarily imply that the geophysical parameter is not affected by the solar cycle; rather it simply reflects the complex nature of the Earth's response to climate forcings.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  8. Limitation of Ground-based Estimates of Solar Irradiance Due to Atmospheric Variations

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Cahalan, Robert F.; Holben, Brent N.

    2003-01-01

    The uncertainty in ground-based estimates of solar irradiance is quantitatively related to the temporal variability of the atmosphere's optical thickness. The upper and lower bounds of the accuracy of estimates using the Langley Plot technique are proportional to the standard deviation of aerosol optical thickness (approx. +/- 13 sigma(delta tau)). The estimates of spectral solar irradiance (SSI) in two Cimel sun photometer channels from the Mauna Loa site of AERONET are compared with satellite observations from SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on UARS (Upper Atmospheric Research Satellite) for almost two years of data. The true solar variations related to the 27-day solar rotation cycle observed from SOLSTICE are about 0.15% at the two sun photometer channels. The variability in ground-based estimates is statistically one order of magnitude larger. Even though about 30% of these estimates from all Level 2.0 Cimel data fall within the 0.4 to approx. 0.5% variation level, ground-based estimates are not able to capture the 27-day solar variation observed from SOLSTICE.

  9. Influence of crystal tilt on solar irradiance of cirrus clouds.

    PubMed

    Klotzsche, Susann; Macke, Andreas

    2006-02-10

    The single and multiple scattering and absorption properties of hexagonal ice columns with different degrees of particle orientation are modeled in the solar spectral range by means of a ray-tracing single-scattering code and a Monte Carlo radiative-transfer code. The scattering properties are most sensitive to particle orientation for the solar zenith angles of 50 degrees (asymmetry parameter) and 90 degrees (single-scattering albedo). Provided that the ice columns are horizontally oriented, the usual assumption of random orientation leads to an overestimation (underestimation) of the reflected (transmitted) solar broadband radiation at high Sun elevation and to an underestimation (overestimation) at medium solar zenith angles. The orientation effect is more (less) pronounced in scattering and transmission (absorption) for smaller ice crystals. PMID:16512547

  10. Proton Irradiation Processing of Early Solar System Solids

    NASA Astrophysics Data System (ADS)

    Wetteland, C. J.; Sickafus, K. E.; Taylor, L. A.; McSween, H. Y.

    2015-07-01

    High-flux protons from Young Stellar Objects may result in secondary processing of early solar system solids. Chondrule precursors may be subjected to heating (possibly melting), nuclear transmutation, comminution, and carbon deposition.

  11. The Sun as a variable star: Solar and stellar irradiance variations; Colloquium of the International Astronomical Union, 143rd, Boulder, CO, Jun. 20-25, 1993

    NASA Technical Reports Server (NTRS)

    Pap, Judit M. (Editor); Froehlich, Claus (Editor); Hudson, Hugh S. (Editor); Tobiska, W. Kent (Editor)

    1994-01-01

    Variations in solar and stellar irradiances have long been of interest. An International Astronomical Union (IAU) colloquium reviewed such relevant subjects as observations, theoretical interpretations, and empirical and physical models, with a special emphasis on climatic impact of solar irradiance variability. Specific topics discussed included: (1) General Reviews on Observations of Solar and Stellar Irradiance Variability; (2) Observational Programs for Solar and Stellar Irradiance Variability; (3) Variability of Solar and Stellar Irradiance Related to the Network, Active Regions (Sunspots and Plages), and Large-Scale Magnetic Structures; (4) Empirical Models of Solar Total and Spectral Irradiance Variability; (5) Solar and Stellar Oscillations, Irradiance Variations and their Interpretations; and (6) The Response of the Earth's Atmosphere to Solar Irradiance Variations and Sun-Climate Connections.

  12. Anomalous effects in silicon solar cell irradiated by 1-MeV protons

    NASA Technical Reports Server (NTRS)

    Kachare, R.; Anspaugh, B. E.

    1989-01-01

    Several silicon solar cells having thicknesses of approximately 63 microns, with and without back-surface fields (BSF), were irradiated with 1-MeV protons having fluences between 10 to the 10th and 10 to the 12th sq cm. The irradiations were performed using both normal and isotropic incidence on the rear surfaces of the cells. It was observed that after irradiation with fluences greater than 10 to the 11th protons/sq cm, all BSF cells degraded at a faster rate than cells without BSF. The irradiation results are analyzed using a model in which irradiation-induced defects in the BSF region are taken into account. Tentatively, it is concluded that an increase in defect density due to the formation of aluminum and proton complexes in BSF cells is responsible for the higher-power loss in the BSF cells compared to the non-BSF cells.

  13. Development of local atmospheric model for estimating solar irradiance in Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Yeap, E. C.; Lau, A. M. S.; Busu, I.; Kanniah, K. D.; Rasib, A. W.; Kadir, W. H. W.

    2014-02-01

    Incoming solar irradiance covers a wide range of wavelengths with different intensities which drives almost every biological and physical cycle on earth at a selective wavelength. Estimation of the intensities of each wavelength for the solar irradiance on the earth surface provides a better way to understand and predict the radiance energy. It requires that the atmospheric and geometric input and the availability of atmospheric parameter is always the main concern in estimating solar irradiance. In this study, a local static atmospheric model for Peninsular Malaysia was built to provide the atmospheric parameters in the estimation of solar irradiance. Ten years of monthly Atmospheric Infrared Sounder (AIRS) average data (water vapor, temperature, humidity and pressure profile) of the Peninsular Malaysia was used for the building of the atmospheric model and the atmospheric model were assessed based on the measured meteorological data with RMSE of 4.7% and 0.7k for both humidity and temperature respectively. The atmospheric model were applied on a well-established radiative transfer model namely SMARTS2. Some modifications are required in order to include the atmospheric model into the radiative transfer model. The solar irradiance results were then assessed with measured irradiance data and the results show that both the radiative transfer model and atmospheric model were reliable with RMSE value of 0.5 Wm-2. The atmospheric model was further validated based on the measured meteorological data (temperature and humidity) provided by the Department of Meteorology, Malaysia and high coefficient of determination with R2 value of 0.99 (RMSE value = 4.7%) and 0.90 (RMSE value = 0.7k) were found for both temperature and humidity respectively.

  14. A semiparametric spatio-temporal model for solar irradiance data

    DOE PAGESBeta

    Patrick, Joshua D.; Harvill, Jane L.; Hansen, Clifford W.

    2016-03-01

    Here, we evaluate semiparametric spatio-temporal models for global horizontal irradiance at high spatial and temporal resolution. These models represent the spatial domain as a lattice and are capable of predicting irradiance at lattice points, given data measured at other lattice points. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple interpolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure. These results indicate a promising approach for modeling irradiance atmore » high spatial resolution consistent with available ground-based measurements. Moreover, this kind of modeling may find application in design, valuation, and operation of fleets of utility-scale photovoltaic power systems.« less

  15. The Solar Spectral Irradiance Measured on Board the International Space Station and the Picard Spacecraft

    NASA Astrophysics Data System (ADS)

    Thuillier, G. O.; Bolsee, D.; Schmidtke, G.; Schmutz, W. K.

    2011-12-01

    On board the International Space Station, the spectrometers SOL-ACES and SOLSPEC measure the solar spectrum irradiance from 17 to 150 nm and 170 to 2900 nm, respectively. On board PICARD launched on 15 June 2010, the PREMOS instrument consists in a radiometer and several sunphotometers operated at several fixed wavelengths. We shall present spectra at different solar activity levels as well as their quoted accuracy. Comparison with similar data from other missions presently running in space will be shown incorporating the PREMOS measurements. Some special solar events will be also presented and interpreted.

  16. Pollen chemistry as a tool for reconstructing past solar and ultraviolet irradiance

    NASA Astrophysics Data System (ADS)

    Jardine, Phillip; Fraser, Wesley; Lomax, Barry; Gosling, William

    2016-04-01

    Despite the importance of solar irradiance as a dominant control on Earth's energy budget, no proxy has been developed that can provide records on timescales of over 10 000 years. No independent empirical record of solar irradiance therefore exists prior to the Holocene, limiting our understanding of the relationships between solar energy inputs, global climate and biotic change over longer timescales. Here, we present a novel proxy based on the chemical composition of sporopollenin, the primary component of the outer walls of pollen and spores (sporomorphs). Sporopollenin chemistry is responsive to levels of ultraviolet-B (UV-B) radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of using fossil sporomorph chemistry as a proxy for past UV-B flux, and by extension total solar irradiance (TSI). Fourier Transform infrared (FTIR) spectroscopy provides an efficient, economical and non-destructive method for measuring phenolic compound concentration on small sample sizes (≤30 sporomorphs/sample). The high preservation potential of sporomorphs in the geologic record, and the conserved nature of sporopollenin chemistry and UV-B response across the Embryophyta, means that this new proxy has the potential to reconstruct UV-B and TSI flux over much longer timescales than has previously been possible. We demonstrate the utility of this proxy with two chemopalynological datasets. Orbital cyclicity is reconstructed using grass pollen from a 150 000 year long sediment record from Lake Bosumtwi in Ghana, and changes in solar output over the last 600 years are reconstructed using pine pollen from Nar Lake in Turkey. This proxy provides a new approach for quantifying and understanding the relationship between UV-B flux, solar insolation and past climate. The unpicking of this information offers the tantalising potential to determine how changes in solar irradiance have driven long-term changes in

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  18. Stratospheric ozone response to a solar irradiance reduction in a quadrupled CO2 environment

    NASA Astrophysics Data System (ADS)

    Jackman, Charles H.; Fleming, Eric L.

    2014-07-01

    We used the Goddard Space Flight Center (GSFC) global two-dimensional (2D) atmospheric model to investigate the stratospheric ozone response to a proposed geoengineering activity wherein a reduced top-of-atmosphere (TOA) solar irradiance is imposed to help counteract a quadrupled CO2 atmosphere. This study is similar to the Geoengineering Model Intercomparison Project (GeoMIP) Experiment G1. Three primary simulations were completed with the GSFC 2D model to examine this possibility: (A) a pre-industrial atmosphere with a boundary condition of 285 ppmv CO2 (piControl); (B) a base future atmosphere with 1140 ppmv CO2 (abrupt4xCO2); and (C) a perturbed future atmosphere with 1140 ppmv CO2 and a 4% reduction in the TOA total solar irradiance (G1). We found huge ozone enhancements throughout most of the stratosphere (up to 40%) as a result of a large computed temperature decrease (up to 18 K) when CO2 was quadrupled (compare simulation abrupt4xCO2 to piControl). Further, we found that ozone will additionally increase (up to 5%) throughout most of the stratosphere with total ozone increases of 1-2.5% as a result of a reduction in TOA total solar irradiance (compare simulation G1 to abrupt4xCO2). Decreases of atomic oxygen and temperature are the main drivers of this computed ozone enhancement from a reduction in TOA total solar irradiance.

  19. Spurious Acceleration Noise on the LISA Spacecraft Due to Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Piotrzkowski, Brandon; Frank, Barret; Bolen, Brett; Larson, Shane

    2016-03-01

    The Laser Interferometer Space Antenna (LISA) is a configuration of three satellites that will precisely measure the distance between each other in order to detect gravitational waves. Therefore, the stability of LISA satellite configuration will be crucial to its ability to measure gravitational waves, as will understanding the noise introduced in the measured gravitational wave signal from various environmental accelerations. Although solar irradiance will certainly be a large source of noise in the desired frequency band and will attempt to disrupt the satellite configuration, previous research has only considered zeroth order calculations of force by irradiance in static systems. To remedy this, we used a geometric and material based approach to calculate the force on the satellites' solar arrays, the only component facing the sun. Running our simulation of LISA based on irradiance data from the VIRGO (Variability of solar IRadiance and Gravity Oscillations) satellite, we examined the Fourier transform of force to find the associated acceleration noise within in the LISA frequency band due to solar irradiance. This research will help isolate the gravitational wave signal when LISA is flown. University of Mississippi.

  20. Reconstruction of the Solar EUV Irradiance as observed with SOHO/SEM and PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Haberreiter, M.; Delouille, V.; Mampaey, B.; Verbeeck, C.; Del Zanna, G.; Ermolli, I.; Kretzschmar, M.; Dominique, M.; Wieman, S. R.; Schmutz, W. K.

    2013-12-01

    The solar EUV spectrum has important effects on the Earth's upper atmosphere. For a detailed investigation of these effects it is important to have a constistent data series of the EUV spectral irradiance available. Here, we present the reconstruction of the solar EUV irradiance based on PSPT and SOHO/EIT images and along with synthetic spectra calculated for six different coronal features representing the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA tool which allows to identify the features based on a consistent brightness classification for each feature. With the SOLMOD code we then calculate intensity spectra for 10 nm to 100 nm for each of the coronal feature. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed time series is then validated against the spectral irradiance as observed with SOHO/SEM and PROBA2/LYRA. Our approach leads to a very good agreement between the reconstructed and the observed spectral irradiance. This is an important step towards the understanding of the variations of the solar EUV spectrum and ultimately its effect on the Earth's upper atmosphere.

  1. Solar Irradiance from GOES Albedo performance in a Hydrologic Model Simulation of Snowmelt Runoff

    NASA Astrophysics Data System (ADS)

    Sumargo, E.; Cayan, D. R.; McGurk, B. J.

    2015-12-01

    In many hydrologic modeling applications, solar radiation has been parameterized using commonly available measures, such as the daily temperature range, due to scarce in situ solar radiation measurement network. However, these parameterized estimates often produce significant biases. Here we test hourly solar irradiance derived from the Geostationary Operational Environmental Satellite (GOES) visible albedo product, using several established algorithms. Focusing on the Sierra Nevada and White Mountain in California, we compared the GOES irradiance and that from a traditional temperature-based algorithm with incoming irradiance from pyranometers at 19 stations. The GOES based estimates yielded 21-27% reduction in root-mean-squared error (average over 19 sites). The derived irradiance is then prescribed as an input to Precipitation-Runoff Modeling System (PRMS). We constrain our experiment to the Tuolumne River watershed and focus our attention on the winter and spring of 1996-2014. A root-mean-squared error reduction of 2-6% in daily inflow to Hetch Hetchy at the lower end of the Tuolumne catchment was achieved by incorporating the insolation estimates at only 8 out of 280 Hydrologic Response Units (HRUs) within the basin. Our ongoing work endeavors to apply satellite-derived irradiance at each individual HRU.

  2. Infrared Cavity Radiometer Reflectometry in Support of Total Solar Irradiance Instruments

    NASA Astrophysics Data System (ADS)

    Hanssen, L. M.; Zeng, J.; Wilthan, B.; Morrill, J. S.; Kopp, G.

    2011-12-01

    A key component required to achieve a high degree of accuracy in satellite solar irradiance measurements using cavity radiometers, is the characterization of the cavity spectral absorptance over the broad spectral range of the Solar output. This includes the infrared region up to at least 10 μm. In order to accurately measure high levels of absorptance of cavities, NIST has developed a laser and integrating sphere based facility (the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR)). The system is used for both radiometer and blackbody cavity characterization. We report the results of reflectance (1 - absorptance) measurements of radiometer cavities designed for two solar irradiance measurement instruments: 1) the Active Cavity Radiometer Irradiance Monitor (ACRIM) and 2) the Total Irradiance Monitor (TIM) instrument on the SORCE and TSIS missions. The measurements were made using the NIST CHILR instrument as well as the Infrared Reference Integrating Sphere (IRIS) for relative spectral reflectance. The IRIS was used to obtain relative spectral reflectance for the TIM cones. The IRIS was also used to obtain the spectral reflectance of other surfaces in the ACRIM instrument that also interact with the incident irradiance and potentially affect the cavity performance. These reflectance results are used to validate previously estimated performance parameters of the two instruments.

  3. Quality assurance of solar UV irradiance in the Arctic.

    PubMed

    Gröbner, Julian; Hülsen, Gregor; Wuttke, Sigrid; Schrems, Otto; De Simone, Sara; Gallo, Veronica; Rafanelli, Claudio; Petkov, Boyan; Vitale, Vito; Edvardsen, Kåre; Stebel, Kerstin

    2010-03-01

    The first Arctic intercomparison of three solar ultraviolet (UV) spectroradiometers and two multifilter radiometers was held in May and June 2009 at Ny-Alesund, Svalbard, Norway. The transportable reference spectroradiometer QASUME acted as reference instrument for this intercomparison. The measurement period extended over eleven days, comprising clear sky and overcast weather conditions. Due to the high latitude, measurements could be performed throughout the day during this period. The intercomparison demonstrated that the solar UV measurements from all instruments agreed to within +/-15% during the whole measurement period, while the spectroradiometer from the Alfred-Wegener Institute agreed to better than +/-5%. This intercomparison has demonstrated that solar UV measurements can be performed reliably in the high-latitude Arctic environment with uncertainties comparable to mid-latitude sites. PMID:20221466

  4. Solar irradiances measured using SPN1 radiometers: uncertainties and clues for development

    NASA Astrophysics Data System (ADS)

    Badosa, J.; Wood, J.; Blanc, P.; Long, C. N.; Vuilleumier, L.; Demengel, D.; Haeffelin, M.

    2014-08-01

    The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, not only for the global component but also for the diffuse and direct. End users look for the best compromise between getting close to state-of-the-art measurements and keeping low capital, maintenance and operating costs. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, which results from laboratory experiments, numerical modeling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the art measurements.

  5. Solar irradiances measured using SPN1 radiometers: uncertainties and clues for development

    NASA Astrophysics Data System (ADS)

    Badosa, J.; Wood, J.; Blanc, P.; Long, C. N.; Vuilleumier, L.; Demengel, D.; Haeffelin, M.

    2014-12-01

    The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, for not only the global but also the diffuse and direct components. End users look for the best compromise between getting close to state-of-the-art measurements and keeping low capital, maintenance and operating costs. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, drawing on laboratory experiments, numerical modelling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the art measurements.

  6. Solar Irradiances Measured using SPN1 Radiometers: Uncertainties and Clues for Development

    SciTech Connect

    Badosa, Jordi; Wood, John; Blanc, Philippe; Long, Charles N.; Vuilleumier, Laurent; Demengel, Dominique; Haeffelin, Martial

    2014-12-08

    The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, not only for the global component but also the diffuse and direct. End users look for the best compromise between getting close to state-of-the-art measurements and keeping capital, maintenance and operating costs to a minimum. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, which results from laboratory experiments, numerical modeling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the-art measurements.

  7. A methodology for calculating percentile values of annual direct normal solar irradiation series

    NASA Astrophysics Data System (ADS)

    Peruchena, Carlos M. Fernández; Ramírez, Lourdes; Silva, Manuel; Lara, Vicente; Bermejo, Diego; Gastón, Martín; Moreno, Sara; Pulgar, Jesús; Liria, Juan; Macías, Sergio; Gonzalez, Rocio; Bernardos, Ana; Castillo, Nuria; Bolinaga, Beatriz; Valenzuela, Rita X.; Zarzalejo, Luis

    2016-05-01

    A detailed knowledge of the solar resource is a critical point in the performance of an economic feasibility analysis of solar thermal electricity plants. In particular, the Direct Normal solar Irradiance (DNI) is the most determining variable in its final energy yield. Inter-annual variations of DNI can be large and seriously compromise the viability of solar energy projects. In this work, a methodology for evaluating the statistical properties of annual DNI series is presented for generating inputs to risk assessments in an economic feasibility analysis of a solar power plant. The methodology relies on the construction of a cumulative distribution function of annual DNI values, which allows for the evaluation of both mean and extreme climate characterization at a particular location in the long term.

  8. Influence of synoptic weather patterns on solar irradiance variability in Europe

    NASA Astrophysics Data System (ADS)

    Parding, Kajsa; Hinkelman, Laura; Liepert, Beate; Ackerman, Thomas; Dagestad, Knut-Frode; Asle Olseth, Jan

    2014-05-01

    Solar radiation is important for many aspects of existence on Earth, including the biosphere, the hydrological cycle, and creatures living on the planet. Previous studies have reported decadal trends in observational records of surface shortwave (SW) irradiance around the world, too strong to be caused by varying solar output. These observed decadal trends have been dubbed "solar dimming and brightening" and are believed to be related to changes in atmospheric aerosols and cloud cover. Because the observed solar variability coincides with qualitative air pollution histories, the dimming and brightening have become almost synonymous with shortwave attenuation by anthropogenic aerosols. However, there are indications that atmospheric circulation patterns have influenced the dimming and brightening in some regions, e.g., Alaska and Scandinavia. In this work, we focus on the role of atmospheric circulation patterns in modifying shortwave irradiance. An examination of European SW irradiance data from the Global Energy Balance Archive (GEBA) shows that while there are periods of predominantly decreasing (~1970-1985) and increasing (~1985-2007) SW irradiance, the changes are not spatially uniform within Europe and in a majority of locations not statistically significant. To establish a connection between weather patterns and sunshine, regression models of SW irradiance are fitted using a daily classification of European weather called Grosswetterlagen (GWL). The GWL reconstructions of shortwave irradiance represent the part of the solar variability that is related to large scale weather patterns, which should be effectively separated from the influence of varying anthropogenic aerosol emissions. The correlation (R) between observed and reconstruced SW irradiance is between 0.31 and 0.75, depending on station and season, all statistically significant (p<0.05, estimated with a bootstrap test). In central and eastern parts of Europe, the observed decadal SW variability is

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  10. Models for obtaining daily global solar irradiation from air temperature data

    NASA Astrophysics Data System (ADS)

    Paulescu, M.; Fara, L.; Tulcan-Paulescu, E.

    2006-03-01

    The study presents a critical assessment of the possibility of global solar irradiation computation by using air temperature instead of sunshine duration with the classical Ångström equations. The reason for this approach comes from the fact that, although the air temperature is a worldwide measured meteorological parameter, this is rarely used in solar radiation estimation techniques. More than that, the literature is very silent concerning the testing of such models in Eastern Europe. Two new global solar irradiation models (to be called AEAT) related to solar irradiation under clear sky conditions and having the minimum and maximum daily air temperature as input parameters were tested and compared with others from the literature against data measured at five stations in Romania in the year 2000. The accuracy of AEAT is acceptable and comparable to that of the models which use sunshine duration or cloud amount as input parameters. Since temperature-based Ångström correlations are strongly sensitive to origin, the approach for AEAT as a tool for potential users is presented in detail. Additionally reported is a new method to increase the generality of AEAT concerning the extension of the geographical application area. Based on overall results it was concluded that air temperature successfully substitutes sunshine duration in the estimation of the available solar energy.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  12. Solar Irradiance observation from Fengyun3 meteorological satellites: recent results and future plan

    NASA Astrophysics Data System (ADS)

    Qi, Jin; Zhang, Peng; Qiu, Hong; Fang, Wei

    2016-04-01

    The Solar Irradiance Monitors (SIM) on-board Fengyun3 (FY3) satellites have been observing Total Solar Irradiance since June 2008. With the lessons from the first two satellites, the SIM on FY3C has two significant improvements by adding sun tracing system and temperature control system, which is named after SIM-II. The SIM-II measurements are first really traceable to World Radiometric Reference and building an on-orbit aging model. TSI from FY3C/SIM-II has been evaluated by comparing with SORCE/TIM and RMIB composite data. The result shows a good consistency. Monitoring of strong solar activity during Oct. 2014, FY3C/SIM-II and SORCE/TIM showed the similar result about solar energy change. For the future plan, we would like to have cooperation with RMIB and PMOD on TSI observation from FY3 early-morning orbit satellite which is designed to launch in 2018. We also plan to develop a new ability to capture daily variance in solar spectral irradiance on the early-morning orbit.

  13. Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors

    NASA Technical Reports Server (NTRS)

    Deland, Matthew T.; Cebula, Richard P.

    1994-01-01

    Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

  14. Modelling the solar irradiance during the Maunder Minimum and the corresponding cooling

    SciTech Connect

    Garduno, R.; Mendoza, B.; Adem, J.

    1996-12-31

    Expressions to compute the solar irradiance as a function of the sun rotation rate, sunspot number and solar cycle length, are deduced. They yield a solar irradiance dimmed by about 0.5% during the Maunder Minimum (1660-1720). This parameter is put in the Adem thermodynamic model as an external forcing to simulate the corresponding climate change. Another forcing used is the preindustrial level of atmospheric CO{sub 2} which reinforces the cooling. The model generates three internal feedbacks: cryosphere, cloudiness and water vapor. The output is a cooling of about 0.5 to 1 C, with respect to present climate, depending on the forcings and feedbacks included. These results agree well with those from other authors and with the few historical records.

  15. Total solar irradiance reconstruction since 1700 using a flux transport model

    NASA Astrophysics Data System (ADS)

    Dasi Espuig, Maria; Krivova, Natalie; Solanki, Sami K.; Jiang, Jie

    Reconstructions of solar irradiance into the past are crucial for studies of solar influence on climate. Models based on the assumption that irradiance changes are caused by the evolution of the photospheric magnetic fields have been most successful in reproducing the measured irradiance variations. Daily magnetograms, such as those from MDI and HMI, provide the most detailed information on the changing distribution of the photospheric magnetic fields. Since such magnetograms are only available from 1974, we used a surface flux transport model to describe the evolution of the magnetic fields on the solar surface due to the effects of differential rotation, meridional circulation, and turbulent diffusivity, before 1974. In this model, the sources of magnetic flux are the active regions, which are introduced based on sunspot group areas, positions, and tilt angles. The RGO record is, however, only available since 1874. Here we present a model of solar irradiance since 1700, which is based on a semi-synthetic sunspot record. The semi-synthetic record was obtained using statistical relationships between sunspot group properties (areas, positions, tilt angles) derived from the RGO record on one hand, and the cycle strength and phase derived from the sunspot group number (Rg) on the other. These relationships were employed to produce daily records of sunspot group positions, areas, and tilt angles before 1874. The semi-synthetic records were fed into the surface flux transport model to simulate daily magnetograms since 1700. By combining the simulated magnetograms with a SATIRE-type model, we then reconstructed total solar irradiance since 1700.

  16. Comparison of Recent Total Irradiance Measurements

    NASA Astrophysics Data System (ADS)

    Helizon, R.; Pap, J.

    2002-12-01

    Total solar irradiance has been measured since 1978 from various satellites. Since the absolute accuracy of the current irradiance measurements is about 0.2%, one needs to compile composite irradiance time series to study long-term changes and to establish whether there are any secular variations over the last two and half decades. In this paper we compare the UARS/ACRIM II and SOHO/VIRGO total irradiance data as well as the SOHO/VIRGO and ACRIM III total irradiance. Our main goal is to validate the newly processed ACRIM II total irradiance. Comparison of the SOHO/VIRGO and ACRIM III data will also help to establish whether the high total irradiance values for the maximum of solar cycle 23 represent real solar, rather than, instrumental events.

  17. A status report on the analysis of the NOAA-9 SBUV/2 sweep mode solar irradiance data

    NASA Technical Reports Server (NTRS)

    Cebula, R. P.; Deland, M. T.; Schlesinger, B. M.; Hudson, R. D.

    1990-01-01

    Monitoring of the near ultraviolet (UV) solar irradiance is important because the solar UV radiation is the primary energy source in the upper atmosphere. The solar irradiance at wavelengths shortward of roughly 300 nm heats the stratosphere via photodissociation of ozone in the Hartley bands. Shortward of 242 nm the solar UV flux photodissociates O2, which is then available for ozone formation. Upper stratosphere ozone variations coincident with UV solar rotational modulation have been previously reported (Gille et al., 1984). Clearly, short and long term solar irradiance observations are necessary to separate solar-forced ozone variations from anthropogenic changes. The SBUV/2 instrument onboard the NOAA-9 spacecraft has made daily measurements of the solar spectral irradiance at approximately 0.15 nm intervals in the wavelength region 160-405 nm at 1 nm resolution since March 1985. These data are not needed to determine the terrestrial ozone overburden or altitude profile, and hence are not utilized in the NOAA Operational Ozone Product System (OOPS). Therefore, assisted by the ST System Corporation, NASA has developed a scientific software system to process the solar sweep mode data from the NOAA-9 instrument. This software will also be used to process the sweep mode solar irradiance data from the NOAA-11 and later SBUV/2 instruments. An overview of the software system and a brief discussion of analysis findings to date are provided. Several outstanding concerns/problems are also presented.

  18. Modelling solar irradiances using ground-based measurements

    NASA Technical Reports Server (NTRS)

    Pap, J. M.; Marquette, W. H.; Donnelly, R. F.

    1991-01-01

    The first results of photometric measurements of Ca-K plage remnants are presented. They show that during the fall of 1986 the remnants gave a significant contribution to the irradiance variations and that the averaged remnant component is less than assumed in the present UV models. The contribution of the plage remnants to the combined plage and remnant index was on average about 13 percent, and it changed with time.

  19. Solar Irradiance Sensor on the ExoMars 2016 Lander

    NASA Astrophysics Data System (ADS)

    Arruego, I.; Apéstigue, V.; Martínez, J.; Jiménez, J. J.; Rivas, J.; González, M.; Álvarez, J.; Azcue, J.; Martín, I.; Canchal, R.

    2015-10-01

    DREAMS-SIS is a radiometer designed to provide in-situ measurements of the Sun irradiance on Mars surface, as well as to estimate the opacity of the Mars atmosphere, due to the suspended dust. It will be included in the DREAMS package (Dust characterization, Risk assessment and Environment Analyzer on the Martian Surface), payload of the EDM (Entry and Descend Module) for the EXOMARS 2016 ESA mission [1]. We report on the development and characteristics of this miniature sensor.

  20. A Reliable and Accurate Long-term Climate Record: Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Rottman, G. J.; Woods, T. N.; Snow, M. A.

    2014-12-01

    Solar irradiance - both total irradiance and spectral irradiance— are primary climate data variables. Because of absorption and scattering by our intervening atmosphere accurate measurements of the Sun are only realized from space observations beginning in about 1978. The long-term accuracies of the resulting data sets are limited by unidentified and uncertain on-orbit instrument degradation. Nevertheless, from numerous observing programs solar variability has been well established for short and intermediate times scales, with additional clear indications of decadal variability associated with the 11-year solar cycle. How can today's solar irradiance measurements be reliably compared with those made in the future, and how will the resulting comparison stand the test of time? There is one technique that shows great promise. The Sun is a star — more or less variable like any and all other stars. Stellar astronomers have a technique of establishing a star's variability with precision of 0.01%, and over arbitrarily long periods of time. From the ground and from space they have success by simply comparing the irradiance of a target star to that of a number of standard stars. (The key here is that there exist many standard stars, and outliers are easily identified and removed from the ensemble.) For stellar comparisons it is straightforward to use a single instrument — same optics and detectors — to observe stars differing by several orders of magnitude in brightness. To observe the Sun and stars with a single instrument is far more problematic as there are easily eight to twelve orders of magnitude differences in brightness. The SOLSTICE (Solar Stellar Irradiance Comparison Experiment) has now been flown twice — on UARS from 1991 to 2005 and on SORCE from 2003 to the present. The SOLSTICE is an ultraviolet spectral instrument measuring irradiance from 115 nm to 300 nm, and it is intentionally designed to observe both the Sun and selected standard stars. In

  1. Annealing results on low-energy proton-irradiated GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Kachare, R.; Anspaugh, B. E.; O'Meara, L.

    1988-01-01

    AlGaAs/GaAs solar cells with an approximately 0.5-micron-thick Al(0.85)Ga(0.15)As window layer were irradiated using normal and isotropic incident protons having energies between 50 and 500 keV with fluence up to 1 x 10 to the 12th protons/sq cm. The irradiated cells were annealed at temperatures between 150 and 300 C in nitrogen ambient. The annealing results reveal that significant recovery in spectral response at longer wavelengths occurred. However, the short-wavelength spectral response showed negligible annealing, irrespective of the irradiation energy and annealing conditions. This indicates that the damage produced near the AlGaAs/GaAs interface and the space-charge region anneals differently than damage produced in the bulk. This is explained by using a model in which the as-grown dislocations interact with irradiation-induced point defects to produce thermally stable defects.

  2. Solar ultraviolet irradiance observed from Southern Argentina; September 1990 to March 1991

    NASA Astrophysics Data System (ADS)

    Frederick, J. E.; Soulen, P. F.; Diaz, S. B.; Smolskaia, I.; Booth, C. R.; Lucas, T.; Neuschuler, D.

    1993-05-01

    A nearly continuous data set of solar ultraviolet spectra irradiance exists for Ushuaia, Argentina, latitude 54°59' S, over the period from mid-September 1990 to mid-March 1991. This includes a season of prolonged depletion in column ozone over Antarctica, 10° or more in latitude poleward of Ushuaia. Cloudiness provides a major source of variance in the measurements. When this influence is removed, the irradiances at wavelengths between 300 and 310 nm are enhanced relative to clear sky calculations based on a 10-year ozone climatology. During December the average noontime irradiance at 306.5 nm, which is a good proxy for erythemal irradiance, is 45% larger than the zonal mean climatological prediction. The largest noontime radiation levels observed at Ushuaia are equivalent to moving 20° in latitude closer to the equator at the summer solstice.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  4. The response of the MLS mesospheric daytime hydroxyl radical and water vapor to the short-term solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Shapiro, A. V.; Rozanov, E.; Shapiro, A.; Wang, S.; Egorova, T. A.; Schmutz, W. K.; Peter, T.

    2011-12-01

    Solar radiation, which is the main energy source in the terrestrial atmosphere, is highly variable on different time-scales. The variations of the SSI may have substantial impact on chemical and physical processes in the atmosphere. The mesospheric hydroxyl radical (OH), which is the main ozone destructor, is produced due to the photolysis of the water vapor (H2O) by highly variable short wave solar radiation. Chemistry-climate models suggest strong response of the mesospheric OH and H2O caused by the solar irradiance variability. However the response was not yet defined with observed data. We analyzed the response of the tropical mean OH and H2O data observed by Aura Microwave Limb Sounder (MLS) to the solar irradiance variations during rotational cycle. We performed the analysis for the two time periods. The data from December 2004 to December 2005 were used to estimate the OH and H2O responses to the solar irradiance variability in high solar activity conditions (when the 27-day rotational cycle is well pronounced). The response for the solar minimum conditions (when the 27-day rotational cycle is vague) was considered using the data from November 2008 to November 2009. We found, for the first time, that during the period of the high solar activity the daily time series of the mesospheric OH correlate well with the solar irradiance at zero time-lag and the correlation coefficient reaches 0.79 at 76-82 km. The H2O for the same period anticorrelates with the solar irradiance at about 6-7 days time-lag with the correlation coefficient up to -0.7. At the same time the OH and H2O responses are negligible for the solar minimum period. This confirms that the 27-day solar cycles in OH, H2O and solar irradiance are physically connected.

  5. The Extreme-Ultraviolet Solar Irradiance Spectrum Observed with the Coronal Diagnostic Spectrometer (CDS) on SOHO

    NASA Astrophysics Data System (ADS)

    Brekke, P.; Thompson, W. T.; Woods, T. N.; Eparvier, F. G.

    2000-06-01

    We present a calibrated solar EUV irradiance spectrum in the ranges 307-380 Å and 515-632 Å. The ``Sun as a star'' spectrum was recorded by the Coronal Diagnostic Spectrometer (CDS) on SOHO on 1997 May 15 using the normal incidence spectrometer (NIS) with a spectral resolution between 0.3 and 0.6 Å. The relatively high spectral resolution allows the separation of blends and the differentiation of weak emission lines. The full-disk spectrum is compared with simultaneous well-calibrated EUV irradiance measurements from a NASA/LASP rocket payload to validate the preflight calibration of CDS. Significant errors in the preflight calibration were found, and a new calibration has been established for the CDS/NIS system. The present spectrum includes emission lines formed in the temperature range 104 to over 106 K. Line fluxes for the most prominent lines are extracted for the calibration and for the solar irradiance studies. This measurement should represent well solar minimum conditions as the daily 10.7 cm radio flux was 73 (units of 10-22 W m-2 Hz-1). A modest spatial resolution, constrained by the observing mode used, allows for the discrimination between quiet and active sun. The calibrated quiet-Sun irradiance spectrum is compared with previous measurements.

  6. How does ionospheric TEC vary if solar EUV irradiance continuously decreases?

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

    2014-12-01

    It is an interesting topic how the ionosphere varies when solar extreme ultraviolet (EUV) irradiance decreases far below normal levels. When extrapolating the total electron content (TEC)-EUV relation, significantly negative TECs at the zero solar EUV point are obtained, which indicates that TEC-EUV variation under extremely low solar EUV (ELSE) conditions does not follow the TEC-EUV trend during normal solar cycles. We suggest that there are four types of nonlinear TEC-EUV variations over the whole EUV range from zero to the solar maximum level. The features of the ionosphere under ELSE conditions were investigated using the TEC extrapolated with cubic TEC-EUV fitting. With the constraint of zero TEC at zero EUV, the cubic fitting takes not only observations but also the trend of the ionosphere (only an extremely weak ionosphere can exist when EUV vanishes) into account. The climatology features of TEC under ELSE conditions may differ from those during normal solar cycles at nighttime. Ionospheric dynamic processes are supposed to still significantly affect the ionosphere under ELSE conditions and induce this difference. With solar EUV decreasing, global electron content (GEC) should vary largely in accordance with the GEC-EUV trend during normal solar cycles, and the seasonal fluctuation of GEC declines, owing to the contraction of the ionosphere.

  7. Solar Irradiance Variability and Its Impacts on the Earth Climate System

    NASA Astrophysics Data System (ADS)

    Harder, J. W.; Woods, T. N.

    The Sun plays a vital role in the evolution of the climates of terrestrial planets. Observations of the solar spectrum are now routinely made that span the wavelength range from the X-ray portion of the spectrum (5 nm) into the infrared to about 2400 nm. Over this very broad wavelength range, accounting for about 97% of the total solar irradiance, the intensity varies by more than 6 orders of magnitude, requiring a suite of very different and innovative instruments to determine both the spectral irradiance and its variability. The origins of solar variability are strongly linked to surface magnetic field changes, and analysis of solar images and magnetograms show that the intensity of emitted radiation from solar surface features in active regions has a very strong wavelength and magnetic field strength dependence. These magnetic fields produce observable solar surface features such as sunspots, faculae, and network structures that contribute in different ways to the radiated output. Semi-empirical models of solar spectral irradiance are able to capture much of the Sun's output, but this topic remains an active area of research. Studies of solar structures in both high spectral and spatial resolution are refining this understanding. Advances in Earth observation systems and high-quality three-dimensional chemical climate models provide a sound methodology to study the mechanisms of the interaction between Earth's atmosphere and the incoming solar radiation. Energetic photons have a profound effect on the chemistry and dynamics of the thermosphere and ionosphere, and these processes are now well represented in upper atmospheric models. In the middle and lower atmosphere the effects of solar variability enter the climate system through two nonexclusive pathways referred to as the top-down and bottom-up mechanisms. The top-down mechanism proceeds through the alteration of the photochemical rates that establish the middle atmospheric temperature structure and

  8. Measurements of solar ultraviolet irradiance with respect to the human body surface

    NASA Astrophysics Data System (ADS)

    Stick, Carsten; Harms, Volker; Pielke, Liane

    1994-07-01

    Solar UV irradiance is measured in Westerland, Germany (54.9 degree(s) N, 8.3 degree(s) E) in the immediate vicinity of the North Sea shoreline. Measurements have been done since July 1993, focussing on the biologically effective UV radiation and the human body geometry. A grid double monochromator radiometer (DM 150, Bentham Instruments Comp., Reading, England) is used to measure the spectral resolution of 1 nm. Weighting the spectral irradiance by the action spectrum for the erythema is more appropriate for determining the biological effectiveness than simply dividing the UV radiation into the UV-A and UV-B wavebands. The erythemal irradiance shows a close relation to the sun angle during the course of a day. The exposure times, calculated from the irradiance and the minimal erythemal doses, suggest that people might underestimate the risk of getting sunburnt before noon. Diffuse radiation scattered from the sky contribute about 70% of the erythemal irradiance at a 45 degree(s) sun angle. A receiver oriented directly to the sun, i.e. 45 degree(s) inclined, receives an additional 30% of the erythemal irradiance measured by a horizontally adjusted cosine response sensor. The relative irradiance of curved surfaces like the skin is determined by UV- B-sensitive paper placed around a cylinder. This device detected UV radiation reflected by the sea, which hardly is measured by horizontally adjusted receivers.

  9. Reconstruction of the solar EUV irradiance as observed with PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Haberreiter, Margit; Delouille, Veronique; Del Zanna, Giulio; Ermolli, Ilaria; Kretzschmar, Matthieu; Mampeay, Benjamin; Dominique, Marie; Schmutz, Werner

    2014-05-01

    The solar EUV spectrum has important effects on the upper atmosphere of the Earth and any planet. For a detailed investigation of these effects it is important to have a constistent data series of the EUV spectral irradiance available. Here, we present the reconstruction of the solar EUV irradiance based on PSPT and SOHO/EIT images and along with synthetic spectra calculated for six different coronal features representing the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA tool which allows to identify the features based on a consistent brightness classification for each feature. With the SOLMOD code we then calculate intensity spectra for 10 nm to 100 nm for each of the coronal feature. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed time series is then validated against the spectral irradiance as observed with PROBA2/LYRA. This is an important step towards the understanding of the variations of the solar EUV spectrum and ultimately its detailed effect on the Earth's upper atmosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  11. What Irradiance Studies Tell Us about Solar/Stellar Convection and Magnetism

    NASA Astrophysics Data System (ADS)

    Foukal, Peter V.

    2010-05-01

    Despite their enormous thermal inertia, many late - type stars exhibit luminosity fluctuations caused by changing photospheric magnetic structures. These fluctuations exist only because of the high heat diffusivity of stellar convection. Were it lower, the dark spots would be surrounded by intense bright rings, as Gene Parker pointed out in 1974. These rings would cancel the spot - induced luminosity dips. Conversely, dark rings around the bright faculae would cancel their positive luminosity contribution. Photometric measurements of this heat diffusivity place independent constraints on solar magnetic diffusivities - a key parameter in dynamo models. Irradiance studies also suggest that the structure of emerging magnetic fields shifts toward lower spatial frequencies with increasing activity. This finding could provide new information on the field source function in dynamo models. Differential and near - IR imaging photometry reveal the decreased temperature gradient of facular magnetic flux tubes and the sunspot- like darkness of their deepest observable layers. Both of these features support current mhd flux tube models. Bolometric imaging measures the wide- band contribution to total irradiance variation, of spot and facular magnetic flux tubes. The remarkably constant solar limb - darkening measured over the past 33 years constrains fluctuations in quiet photospheric temperature gradient and thus, in global convective efficiency over the past three solar cycles. Reconstruction of irradiance variation over past millennia relies on radio- isotope studies. These provide many interesting insights, but they assume that C14 and Be10 are formed only by solar modulation of the galactic cosmic ray flux. This assumption would break down if solar activity and particle fluxes much exceeded levels experienced in cycle 19. Such a "hyperactive” Sun would vary more in its radiative outputs, be dimmer in total irradiance, although brighter in the EUV and X rays. Work is

  12. Solar total irradiance variations and the global sea surface temperature record

    SciTech Connect

    Reid, G.C. Univ. of Colorado, Boulder )

    1991-02-20

    The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the 11-year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the solar constant) that is in phase with the solar-cycle envelope, supporting and updating an earlier conclusion by Eddy (1976) that such variations could have played a major role in climate change over the past millennium. Measurements of the total irradiance from spacecraft, rockets, and balloons over the past 25 years have provided evidence of long-term variations and have been used to develop a simple linear relationship between irradiance and the envelope of the sunspot cycle. This relationship has been used to force a one-dimensional model of the thermal structure of the ocean, consisting of a 100-m mixed layer coupled to a deep ocean and including a thermohaline circulation. The model was started in the mid-seventeenth century, at the time of the Maunder Minimum of solar activity, and mixed-layer temperatures were calculated at 6-month intervals up to the present. The total range of irradiance values during the period was about 1%, and the total range of SST was about 1C. Cool periods, when temperatures were about 0.5C below present-day values, were found in the early decades of both the nineteenth and twentieth centuries. The results can be taken as indicating that solar variability has been an important contributor to global climate variations in recent decades. The growing atmospheric burden of greenhouse gases may well have played an important role in the immediate past.

  13. Absolute Zero

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.; Sheibley, D.; Belloni, M.; Stamper-Kurn, D.; Vinen, W. F.

    2006-12-01

    Absolute Zero is a two hour PBS special attempting to bring to the general public some of the advances made in 400 years of thermodynamics. It is based on the book “Absolute Zero and the Conquest of Cold” by Tom Shachtman. Absolute Zero will call long-overdue attention to the remarkable strides that have been made in low-temperature physics, a field that has produced 27 Nobel Prizes. It will explore the ongoing interplay between science and technology through historical examples including refrigerators, ice machines, frozen foods, liquid oxygen and nitrogen as well as much colder fluids such as liquid hydrogen and liquid helium. A website has been established to promote the series: www.absolutezerocampaign.org. It contains information on the series, aimed primarily at students at the middle school level. There is a wealth of material here and we hope interested teachers will draw their student’s attention to this website and its substantial contents, which have been carefully vetted for accuracy.

  14. Local short-term variability in solar irradiance

    NASA Astrophysics Data System (ADS)

    Lohmann, Gerald M.; Monahan, Adam H.; Heinemann, Detlev

    2016-05-01

    Characterizing spatiotemporal irradiance variability is important for the successful grid integration of increasing numbers of photovoltaic (PV) power systems. Using 1 Hz data recorded by as many as 99 pyranometers during the HD(CP)2 Observational Prototype Experiment (HOPE), we analyze field variability of clear-sky index k* (i.e., irradiance normalized to clear-sky conditions) and sub-minute k* increments (i.e., changes over specified intervals of time) for distances between tens of meters and about 10 km. By means of a simple classification scheme based on k* statistics, we identify overcast, clear, and mixed sky conditions, and demonstrate that the last of these is the most potentially problematic in terms of short-term PV power fluctuations. Under mixed conditions, the probability of relatively strong k* increments of ±0.5 is approximately twice as high compared to increment statistics computed without conditioning by sky type. Additionally, spatial autocorrelation structures of k* increment fields differ considerably between sky types. While the profiles for overcast and clear skies mostly resemble the predictions of a simple model published by , this is not the case for mixed conditions. As a proxy for the smoothing effects of distributed PV, we finally show that spatial averaging mitigates variability in k* less effectively than variability in k* increments, for a spatial sensor density of 2 km-2.

  15. Measurement and modeling of solar irradiance components on horizontal and tilted planes

    SciTech Connect

    Padovan, Andrea; Col, Davide del

    2010-12-15

    In this work new measurements of global and diffuse solar irradiance on the horizontal plane and global irradiance on planes tilted at 20 and 30 oriented due South and at 45 and 65 oriented due East are used to discuss the modeling of solar radiation. Irradiance data are collected in Padova (45.4 N, 11.9 E, 12 m above sea level), Italy. Some diffuse fraction correlations have been selected to model the hourly diffuse radiation on the horizontal plane. The comparison with the present experimental data shows that their prediction accuracy strongly depends on the sky characteristics. The hourly irradiance measurements taken on the tilted planes are compared with the estimations given by one isotropic and three anisotropic transposition models. The use of an anisotropic model, based on a physical description of the diffuse radiation, provides a much better accuracy, especially when measurements of the diffuse irradiance on the horizontal plane are not available and thus transposition models have to be applied in combination with a diffuse fraction correlation. This is particularly significant for the planes oriented away from South. (author)

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  17. Solar Irradiance Variability: Validation of Satellite-Based Assessment and Prospective Enhancements

    NASA Astrophysics Data System (ADS)

    Nonnenmacher, L.; Coimbra, C.

    2013-12-01

    Based on the technological advances and recent growth rates in deployment, solar energy will contribute significantly in the prospective global energy system. However, the intermittent output characteristics of solar energy systems pose a major challenge for the integration of this renewable power resource into the existing power grid. The intra-day solar variability causing output ramps is primarily caused by clouds and aerosols interacting with solar radiation passing through the atmosphere. Recent advances proposed different methods to assess and quantify irradiance fluctuations at the earth's surface. While remote sensing models based on satellite imagery can provide variability data for a vast domain, the temporal resolution is low and show a dearth of validation. In contrast to that, the spatial resolution of ground based instrumentation is limited whereas temporal resolution, precision and accuracy is high. Our validation of satellite based assessment of solar variability with ground truth measurements shows that the satellite based methods provide an accurate picture of variability with half hourly temporal resolution. However, half hourly variability values disregard a large portion of amplitude and frequency of solar variability on shorter timescales. This contribution seeks to investigate the characteristics of different measures of solar irradiance variability, evaluates the accuracy of common variability assessment techniques and finally proposes methods to estimate solar variability in different microclimates under different atmospheric conditions with improved accuracy. Our work shows a novel hybrid approach based on a combination of satellite and sky imager observations to scale down variability values from a 30 minute resolution to a significantly shorter timescale. Current research investigates the applicability and universality of a scaling-law with multiple inputs to derive temporal variability characteristics.

  18. Solar irradiance variability: a six-year comparison between SORCE observations and the SATIRE model

    NASA Astrophysics Data System (ADS)

    Ball, W. T.; Unruh, Y. C.; Krivova, N. A.; Solanki, S.; Harder, J. W.

    2011-06-01

    Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total solar irradiance and broken down into spectral regions on timescales of several years. Methods: We use the SATIRE model and compare modeled total solar irradiance (TSI) with TSI measurements over the period 25 February 2003 to 1 November 2009. Spectral solar irradiance over 200-1630 nm is compared with the SIM instrument on SORCE over the period 21 April 2004 to 1 November 2009. We discuss the overall change in flux and the rotational and long-term trends during this period of decline from moderate activity to the recent solar minimum in ~10 nm bands and for three spectral regions of significant interest: the UV integrated over 200-300 nm, the visible over 400-691 nm and the IR between 972-1630 nm. Results: The model captures 97% of the observed TSI variation. This is on the order at which TSI detectors agree with each other during the period considered. In the spectral comparison, rotational variability is well reproduced, especially between 400 and 1200 nm. The magnitude of change in the long-term trends is many times larger in SIM at almost all wavelengths while trends in SIM oppose SATIRE in the visible between 500 and 700 nm and again between 1000 and 1200 nm. We discuss the remaining issues with both SIM data and the identified limits of the model, particularly with the way facular contributions are dealt with, the limit of flux identification in MDI magnetograms during solar minimum and the model atmospheres in the IR employed by SATIRE. However, it is unlikely that improvements in these areas will significantly enhance the agreement in the long-term trends. This disagreement implies that some mechanism other than surface magnetism is causing SSI variations, in particular between 2004 and 2006, if the SIM data are correct. Since SATIRE was able to reproduce UV irradiance between 1991 and 2002 from UARS, either the solar mechanism for SSI

  19. The Extreme Ultraviolet Contributions to the Solar Irradiance Reference Spectrum (SIRS)

    NASA Astrophysics Data System (ADS)

    Chamberlin, P. C.; Woods, T. N.; Harder, J. W.; Hock, R. A.; Snow, M.

    2008-12-01

    The Whole Heliosphere Interval (WHI) was a coordinated effort with inputs from over 50 models and observatories, both satellite and ground based, to characterize the Sun and heliosphere during solar minimum conditions. The time period selected for this quiet Sun WHI campaign was April 10-16, 2008. One of the goals of the solar minimum WHI was to produce a definitive Solar Irradiance Reference Spectrum (SIRS) for quiet Sun conditions ranging in wavelength from 0.1 nm up to 2400 nm. During this WHI campaign on April 14, 2008, a sounding rocket was launched from White Sands Missile Range that observed the solar spectral irradiance in these solar minimum conditions in the extreme ultraviolet (EUV) wavelength range from 0.1-106 nm as well as the bright hydrogen Lyman alpha emission at 121.6 nm. The rocket observations from 6.0-106.0 nm and at 0.1 nm spectral resolution are the EUV input for the SIRS. These rocket EUV measurements are discussed following a brief introduction to the entire SIRS spectrum developed for the WHI campaign.

  20. Simulated solar light irradiation of mesotrione in natural waters.

    PubMed

    Ter Halle, Alexandra; Richard, Claire

    2006-06-15

    Photolysis is expected to be a major degradation process for pollutants in surface waters. We report here the first photodegradation study on mesotrione, a new triketone herbicide for use in maize. In a first step, we investigated the direct photolysis of mesotrione at 365 nm from a kinetic and analytical point of view. Mesotrione sensitizes its own oxidation through singlet oxygen formation and sensitizes the oxidation of H-donors through electron or H-atom transfer. In a second step, irradiation experiments were performed under conditions prevalent in the aqueous environment. Mesotrione in submicromolar concentrations was exposed to simulated sunlight, in addition to Suwannee River natural organic matter and/or nitrates. Suwannee River natural organic matter sensitizes the oxidation of mesotrione through the intermediacy of singlet oxygen, and the rate of mesotrione transformation is significantly enhanced for Suwannee River natural organic matter concentrations equal to or above 10 mg/L. Nitrates played a negligible role in SRNOM solutions. PMID:16830551

  1. Absolute Stellar Parameters of KIC 09246715: A Double-giant Eclipsing System with a Solar-like Oscillator

    NASA Astrophysics Data System (ADS)

    Hełminiak, K. G.; Ukita, N.; Kambe, E.; Konacki, M.

    2015-11-01

    We present our results of a combined analysis of radial velocity and light curves (LCs) of a double-lined spectroscopic and eclipsing binary KIC 09246715, observed photometrically by the Kepler satellite and spectroscopically with the OAO-1.88 m telescope with the HIgh-Dispersion Echelle Spectrograph. The target was claimed to be composed of two red giants, one of which is showing solar-like oscillations. We have found that the mass and radius of the primary are {M}1=2.169+/- 0.024 {M}⊙ and {R}1=8.47+/- 0.13 {R}⊙ , and of the secondary are {M}2=2.143+/- 0.025 {M}⊙ and {R}2=8.18+/- 0.09 {R}⊙ , which confirms their double-giant status. Our secondary is the star to which the oscillations were attributed. Results of its previous asteroseismic analysis are in agreement with ours, only significantly less precise, but the subsequent LC-based study failed to derive the correct mass and radius of our primary. KIC 09246715 is one of the rare cases where asteroseismic parameters of a solar-like oscillator were confirmed by an independent method and only the third example of a Galactic double-giant eclipsing binary with masses and radii measured with precision below 2%.

  2. The Development of a New Model of Solar EUV Irradiance Variability

    NASA Technical Reports Server (NTRS)

    Warren, Harry; Wagner, William J. (Technical Monitor)

    2002-01-01

    The goal of this research project is the development of a new model of solar EUV (Extreme Ultraviolet) irradiance variability. The model is based on combining differential emission measure distributions derived from spatially and spectrally resolved observations of active regions, coronal holes, and the quiet Sun with full-disk solar images. An initial version of this model was developed with earlier funding from NASA. The new version of the model developed with this research grant will incorporate observations from SoHO as well as updated compilations of atomic data. These improvements will make the model calculations much more accurate.

  3. Solar Irradiance Reference Spectra (SIRS) for IHY2007 Whole Heliosphere Interval (WHI)

    NASA Astrophysics Data System (ADS)

    Woods, T.; Chamberlin, P.; Snow, M.; Harder, J.

    2008-12-01

    The IHY2007 Whole Heliosphere Interval (WHI) for solar Carrington Rotation 2068 (20 March to 16 April 2008) has been very successful in obtaining a wide variety of solar, heliospheric, and planetary observations during times of solar cycle minimum conditions. One of these efforts is the generation of solar irradiance reference spectra (SIRS) from 0.1 nm to 2400 nm using a combination of satellite and sounding rocket observations. These reference spectra include daily satellite observations from TIMED Solar EUV Experiment (SEE) from 0.1 nm to 116 nm and from Solar Radiation and Climate Experiment (SORCE) instruments from 116 nm to 2400 nm. The EUV range is also improved with higher spectral resolution observations from 6 nm to 105 nm using the prototype SDO EUV Variability Experiment (EVE) aboard a sounding rocket launched on 14 April 2008. The SIRS result is an important accomplishment in that it is the first time in having simultaneous measurements over the full spectral coverage up to 2400 nm and during solar cycle minimum conditions. The SIRS data from 0.1 nm to 2400 nm and in 0.1-nm intervals (on 0.05 nm centers) are available from http://ihy2007.org/WHI/.

  4. Photolysis Kinetics, Mechanisms, and Pathways of Tetrabromobisphenol A in Water under Simulated Solar Light Irradiation.

    PubMed

    Wang, Xiaowen; Hu, Xuefeng; Zhang, Hua; Chang, Fei; Luo, Yongming

    2015-06-01

    The photolysis of tetrabromobisphenol A (TBBPA) in aqueous solution under simulated solar light irradiation was studied under different conditions to find out mechanisms and pathways that control the transformation of TBBPA during photoreaction. Particular attention was paid to the identification of intermediates and elucidation of the photolysis mechanism of TBBPA by UPLC, LC/MS, FT-ICR-MS, NMR, ESR, and stable isotope techniques ((13)C and (18)O). The results showed that the photolysis of TBBPA could occur under simulated solar light irradiation in both aerated and deaerated conditions. A magnetic isotope effect (MIE)-hydrolysis transformation was proposed as the predominant pathway for TBBPA photolysis in both cases. 2,6-Dibromophenol and two isopropylphenol derivatives were identified as photooxidation products of TBBPA by singlet oxygen. Reductive debromination products tribromobisphenol A and dibromobisphenol A were also observed. This is the first report of a photolysis pathway involving the formation of hydroxyl-tribromobisphenol A. PMID:25936366

  5. Comparison between satellite and instrumental solar irradiance data at the city of Athens, Greece

    NASA Astrophysics Data System (ADS)

    Markonis, Yannis; Dimoulas, Thanos; Atalioti, Athina; Konstantinou, Charalampos; Kontini, Anna; Pipini, Magdalini-Io; Skarlatou, Eleni; Sarantopoulos, Vasilis; Tzouka, Katerina; Papalexiou, Simon; Koutsoyiannis, Demetris

    2015-04-01

    In this study, we examine and compare the statistical properties of satellite and instrumental solar irradiance data at the capital of Greece, Athens. Our aim is to determine whether satellite data are sufficient for the requirements of solar energy modelling applications. To this end we estimate the corresponding probability density functions, the auto-correlation functions and the parameters of some fitted simple stochastic models. We also investigate the effect of sample size to the variance in the temporal interpolation of daily time series. Finally, as an alternative, we examine if temperature can be used as a better predictor for the daily irradiance non-seasonal component instead of the satellite data. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  6. The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.

    NASA Technical Reports Server (NTRS)

    Ghosh, S.; Sargent, G. A.

    1972-01-01

    Study regions of lattice disorder produced in lithium-doped float-zone melted n/p-type silicon solar cells by irradiation with monoenergetic neutrons at doses between 10 to the 10th and 10 to the 13th per cu cm. The defect regions were revealed by chemically etching the surface of the solar cells and by observing carbon replicas in an electron microscope. It was found that the defect density increased with increasing irradiation dose and increased lithium content, whereas the average defect diameter was found to decrease. From thermal annealing experiments it was found that in the lithium-doped material the defect structure was stable at temperatures between 300 and 1200 K. This was found to be in contrast to the undoped material where at the lowest doses considerable annealing was observed to occur. These results are discussed in terms of the theoretical predictions and models of defect clusters proposed by Gossick (1959) and Crawford and Cleland (1959).

  7. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    NASA Astrophysics Data System (ADS)

    Sathyanarayana Bhat, P.; Rao, Asha; Sanjeev, Ganesh; Usha, G.; Priya, G. Krishna; Sankaran, M.; Puthanveettil, Suresh E.

    2015-06-01

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5-100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance-frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 -1016 cm-3.

  8. Researches of the Electrotechnical Laboratory, no. 830: Measurement of the solar spectral irradiance at Tanashi, Tokyo (III)

    NASA Astrophysics Data System (ADS)

    Habu, M.; Suzuki, M.; Nagasaka, T.

    1983-01-01

    Spectral irradiance on the horizontal plane produced by global solar radiation, that is, the combination of direct solar radiation and sky brightness was measured. Measured data of 318 sets were obtained and are classified according to seasons, grades of atmospheric turbidity, and total cloud amount. The relationships between the correlated color temperature of solar radiation and solar altitude, between the chromaticity coordinates of solar radiation and the Planckian locus, and between the illuminance produced by global solar radiation and solar altitude were examined. Tables show untreated measured values for each set, and data obtained by linear interpolation from the measured values. The spectral irradiance curve is given for easier intutitional understanding of the measured values.

  9. Comparison of high-resolution solar irradiance spectra and the solar luminosity in the period 1980-1989

    NASA Technical Reports Server (NTRS)

    Mitchell, Walter E., Jr.

    1992-01-01

    In this research, we aim to determine to what extent the solar irradiance changes measured through the 1980's from orbiting vehicles are accompanied by spectroscopic irradiance changes observable from the ground. We describe fractional changes in line absorption as 'blanketing'. In section 2, we briefly review results obtained in an earlier project and which have been published. Section 3 describes the data of this investigation; section 4 describes the data reduction; section 5 describes the observational results in terms of blanketing; and section 6 describes the interpretation of the measured changes. Section 7 contains an outline of possible uses for Doppler-shift data that emerges with the measurements of the blanketing variations. Section 8 is an outline for future research suggested by our results in this project.

  10. Interannual variability in solar ultraviolet irradiance over decadal time scales at latitude 55 degrees south.

    PubMed

    Frederick, J E; Manner, V W; Booth, C R

    2001-12-01

    Ground-based measurements of solar UV spectral irradiance made from Ushuaia, Argentina at latitude 55 degrees S reveal a large degree of variability among corresponding months of different years over the period from September 1990 through April 1998. The magnitude and wavelength dependence of year-to-year changes in monthly spectral UV-B irradiation are consistent with expectations based on the behavior of column ozone and cloudiness. When combined with satellite measurements of column ozone, a regression model fit to the ground-based data set allows estimates of monthly UV-B irradiation over a time frame of two decades, 1978-1998, during several months of the year. Results show a general increase in ground-level irradiation at 305.0 nm from the end of the 1970s to the early 1990s during calendar months from September through December. This is followed by generally smaller irradiances through the middle to late 1990s for all months except November, where the increase continues through the end of the data record. The long-term variability in monthly irradiation over the time period studied is more complicated than can be described by a simple linear trend. PMID:11783932

  11. The functional role of tabular structures for large reef fishes: avoiding predators or solar irradiance?

    NASA Astrophysics Data System (ADS)

    Kerry, J. T.; Bellwood, D. R.

    2015-06-01

    Large reef fishes may often be seen sheltering under tabular structures on coral reefs. There are two principle explanations for this behaviour: avoidance of predation or avoidance of solar irradiance. This study sought supporting evidence to distinguish between these two explanations by examining the usage of tabular structures on a shallow mid-shelf reef of the Great Barrier Reef at midday and sunset. If predation avoidance is most important, usage should increase towards sunset; conversely, if avoidance of solar radiation is most important, more fishes should use cover at midday. Underwater video observations revealed that tabular structures were extensively used by large reef fishes at midday, being characterised by numerous species, especially Lutjanidae and Haemulidae. In contrast, at sunset, tabular structures were used by significantly fewer large reef fishes, being characterised mostly by species of unicornfish ( Naso spp.). Resident times of fishes using tabular structures were also significantly longer at midday (28:06 ± 5:55 min) than at sunset (07:47 ± 2:19 min). The results suggest that the primary function of tabular structures for large reef fishes is the avoidance of solar irradiance. This suggestion is supported by the position of fishes when sheltering. The majority of large reef fishes were found to shelter under the lip of tabular structure, facing outwards. This behaviour is thought to allow protection from harmful downwelling UV-B irradiance while allowing the fish to retain photopic vision and survey more of the surrounding area. These findings help to explain the importance of tabular structures for large reef fishes on coral reefs, potentially providing a valuable energetic refuge from solar irradiance.

  12. An investigation of the energy balance of solar active regions using the ACRIM irradiance data

    NASA Technical Reports Server (NTRS)

    Petro, L. D.

    1986-01-01

    The detection of a significant correlation between the solar irradiance, corrected for flux deficit due to sunspots, and both the 205 nm flux and a photometric facular index were examined. A detailed analysis supports facular emission as the more likely source of correlation with the corrected radiance, rather then the error in sunspot correction. A computer program which simulates two dimensional convection in a compressible, stratified medium was investigated. Subroutines to calculate ionization and other thermodynamic variables were also completed.

  13. Far ultraviolet and extreme ultraviolet rocket instrumentation for measuring the solar spectral irradiance and terrestrial airglow

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Bailey, Scott M.; Solomon, Stanley C.; Rottman, Gary J.

    1992-01-01

    A sounding-rocket experiment is being developed for the study of EUV spectral irradiance and its effects on the upper atmosphere, using three solar EUV instruments devised by the Laboratory for Atmospheric and Space Physics. These include a 25-cm Rowland circle EUV spectrograph, an array of Si X-UV photodiodes, and an X-UV imager with 20 arcsec resolution of the sun.

  14. Far ultraviolet and extreme ultraviolet rocket instrumentation for measuring the solar spectral irradiance and terrestrial airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Bailey, Scott M.; Solomon, Stanley C.; Rottman, Gary J.

    1992-06-01

    A sounding-rocket experiment is being developed for the study of EUV spectral irradiance and its effects on the upper atmosphere, using three solar EUV instruments devised by the Laboratory for Atmospheric and Space Physics. These include a 25-cm Rowland circle EUV spectrograph, an array of Si X-UV photodiodes, and an X-UV imager with 20 arcsec resolution of the sun.

  15. Ion irradiation: its relevance to the evolution of complex organics in the outer solar system.

    PubMed

    Strazzulla, G

    1997-01-01

    Ion irradiation of carbon containing ices produces several effects among which the formation of complex molecules and even refractory organic materials whose spectral color and molecular complexity both depend on the amount of deposited energy. Here results from laboratory experiments are summarized. Their relevance for the formation and evolution of simple molecules and complex organic materials on planetary bodies in the external Solar System is outlined. PMID:11541336

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  17. The Short-term Relationship of Ionospheric Electron Density With Solar Irradiance and Geomagnetic Activity in Daily Observations

    NASA Astrophysics Data System (ADS)

    Wang, X.; Sun, Q.; Eastes, R.; Bailey, S.; Reinisch, B.; Valladares, C.; Woods, T.

    2006-12-01

    The short-term relationship (~ 27-day and less) between equatorial ionospheric electron density, solar irradiance and geomagnetic activity in daily observations has been studied. Hourly averages of the Total Electron Content (TEC) and foF2 are used as measures of electron content at local times of 700-800 LT, 1200- 1300 LT and 1700-1800 LT from 1998 to 1999. Hourly measurements of Dst and daily measurements (6-19 nm) of the solar soft X-ray irradiances from the SNOE satellite provide the geomagnetic activity and solar irradiance information. These data are decomposed into components at ~3-day, ~9-day and ~27-day scales using a 3-band wavelet. This 3-band wavelet allows better isolation of the 27 day variations than the 2-band wavelets available in commercial software packages. At each scale, correlations of ionospheric electron content with solar irradiance and Dst are calculated. The ionosphere has the highest correlation with solar irradiance at the~27-day scales, where the correlation with TEC is 0.8. At ~3-day and ~9-day scales, the ionosphere has a more significant correlation with geomagnetic activity than with solar irradiance. At ~3-day scales, TEC has a correlation of 0.4 with Dst. With both solar irradiances and Dst, and at all three time scales, TEC has higher correlations than foF2. The correlations also change with local time. The correlations with TEC increase from morning to afternoon, when either using solar irradiances or Dst, while the correlations with foF2 do not change significantly or even decrease from morning to afternoon.

  18. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

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

  19. Effect of front and rear incident proton irradiation on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, Bruce; Kachare, Ram

    1987-01-01

    Four solar cell types of current manufacture were irradiated through the front and rear surfaces with protons in the energy range between 1 and 10 MeV. The solar cell parameters varied for this study were cell thickness and back surface field (BSF) vs. no BSF. Some cells were irradiated at normal incidence and an equal number were irradiated with simulated isotropic fluences. The solar cell electrical characteristics were measured under simulated AM0 illumination after each fluence. Using the normal incidence data, proton damage coefficients were computed for all four types of cells for both normal and omnidirectional radiation fields. These were found to compare well with the omnidirectional damage coefficients derived directly from the rear-incidence radiation data. Similarly, the rear-incidence omnidirectional radiation data were used to compute appropriate damage coefficients. A method for calculating the effect of a spectrum of energies is derived from these calculations. It is suitable for calculating the degradation of cells in space when they have minimal rear-surface shielding.

  20. Higher Efficiency for Quasi-Solid State Dye Sensitized Solar Cells Under Low Light Irradiance

    NASA Astrophysics Data System (ADS)

    Desilva, Ajith; Bandara, T. M. W. J.; Fernado, H. D. N. S.; Fernando, P. S. L.; Dissanayake, M. A. K. L.; Jayasundara, W. J. M. J. S. R.; Furlani, M.; Mellander, B.-E.

    2014-03-01

    Dye-sensitized solar cells (DSSCs), lower cost solar energy conversion devices are alternative green energy source. The liquid based electrolyte DSSCs have higher efficiencies with many practical issues while the quasi-solid-state DSSCs resolve the key problems but efficiencies are relatively low. Polyacrylonitrile (PAN) based gel polymer electrolytes were fabricated as DSSCs by incorporating ethylene carbonate and propylene carbonate plasticizers and tetrapropylammonium iodide salt. A thin layer of electrolyte was sandwiched between the TiO2 anode (sensitized with N719 dye) and the Pt counter electrode. The electrolyte had an ionic conductivity of 2.6 mS/cm at 25 degrees of Celsius. DSSCs incorporating this gel electrolyte revealed Vsc circuit, Jsc, fill factor (FF) and efficiency values of 0.71 V, 11.8 mA, 51 percent and 4.2 percent respectively under 1 sun irradiation. The efficiency of the cell increased with decreasing solar irradiance achieving up to 10 percent efficiency and 80 percent FF at low irradiance values. This work uncovers that quasi-solid state DSSCs can reach efficiencies close to that of liquid electrolytes based cells.

  1. Comparison of the Changes in the Visible and Infrared Irradiance Observed by the SunPhotometers on EURECA to the UARS Total Solar and UV Irradiances

    NASA Technical Reports Server (NTRS)

    Pap, Judit

    1995-01-01

    Solar irradiance in the near-UV (335 nm), visible (500 nm) and infrared (778 nm) spectral bands has been measured by the SunPhotometers developed at the World Radiation Center, Davos, Switzerland on board the European Retrievable Carrier between August 1992 and May 1993. Study of the variations in the visible and infrared irradiance is important for both solar and atmospheric physics. The purpose of this paper is to examine the temporal variations observed in the visible and infrared spectral bands after eliminating the trend in the data mainly related to instrument degradation. The effect of active regions in these spectral irradiances is clearly resolved. Variations in the visible and infrared irradiances are compared to total solar irradiance observed by the SOVA2 radiometer on the EURECA platform and by the ACRIMII radiometer on UARS as well as to UV observations of the UARS and NOAA9 satellites. The space-borne spectral irradiance observations are compared to the photometric sunspot deficit and CaII K irradiance measured at the San Fernando Observatory, California State University at Northridge in order to study the effect of active regions in detail.

  2. Tests for the properties of solar gravity mode signals in total irradiance observations

    NASA Astrophysics Data System (ADS)

    Kroll, Ronald J.; Hill, Henry A.; Jian, Chen

    It has been found that a significant fraction of the gravity mode power density in the total irradiance observations appears in sidebands of classified eigenfrequencies. These sidebands are interpreted as harmonics of the rotational frequencies of the solar surface. The power density distributions in the sidebands are consistent with the observed differential rotation of the photosphere and the degree classifications of the respective gravity modes. These findings give further evidence that gravity mode signals are present in the total irradiance observations as well as give an independent check on the gravity mode detections and the l(ital) classifications. The small fraction of the power density remaining at the eigenfrequency of the gravity mode can account for the difficulty that has been experienced in detecting gravity mode signals in total irradiance observations.

  3. Correlation of electron and proton irradiation-induced damage in InP solar cells

    SciTech Connect

    Walters, R.J.; Summers, G.P.; Messenger, S.R.; Burke, E.A.

    1995-10-01

    When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using `displacement damage dose` which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

  4. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Astrophysics Data System (ADS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1995-10-01

    When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

  5. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Technical Reports Server (NTRS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1995-01-01

    When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

  6. Response of the upper atmosphere to variations in the solar soft x-ray irradiance. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Bailey, Scott Martin

    1995-01-01

    Terrestrial far ultraviolet (FUV) airglow emissions have been suggested as a means for remote sensing the structure of the upper atmosphere. The energy which leads to the excitation of FUV airglow emissions is solar irradiance at extreme ultraviolet (EUV) and soft x-ray wavelengths. Solar irradiance at these wavelengths is known to be highly variable; studies of nitric oxide (NO) in the lower thermosphere have suggested a variability of more than an order of magnitude in the solar soft x-ray irradiance. To properly interpret the FUV airflow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N2 to infer the flux of photoelectrons in the atmosphere and thus to infer the magnitude of the solar irradiance. This dissertation presents the first simultaneous measurements of the FUV airglow, the major atmospheric constituent densities, and the solar EUV and soft x-ray irradiances. The measurements were made on three flights of an identical sounding rocket payload at different levels of solar activity. The linear response in brightness of the LBH bands to variations in solar irradiance is demonstrated. In addition to the N2 LBH bands, atomic oxygen lines at 135.6 and 130.4 nm are also studied. Unlike the LBH bands, these emissions undergo radiative transfer effects in the atmosphere. The OI emission at 135.6 nm is found to be well modeled using a radiative transfer calculation and the known excitation processes. Unfortunately, the assumed processes leading to OI 130.4 nm excitation are found to be insufficient to reproduce the observed variability of this emission. Production of NO in the atmosphere is examined; it is shown that a lower than previously reported variability in the solar soft x-ray irradiance is required to explain the variability of NO.

  7. Comparison of Total Solar Irradiance with NASA/NSO Spectromagnetograph Data in Solar Cycles 22 and 23

    NASA Technical Reports Server (NTRS)

    Jones, Harrison P.; Branston, Detrick D.; Jones, Patricia B.; Popescu, Miruna D.

    2002-01-01

    An earlier study compared NASA/NSO Spectromagnetograph (SPM) data with spacecraft measurements of total solar irradiance (TSI) variations over a 1.5 year period in the declining phase of solar cycle 22. This paper extends the analysis to an eight-year period which also spans the rising and early maximum phases of cycle 23. The conclusions of the earlier work appear to be robust: three factors (sunspots, strong unipolar regions, and strong mixed polarity regions) describe most of the variation in the SPM record, but only the first two are associated with TSI. Additionally, the residuals of a linear multiple regression of TSI against SPM observations over the entire eight-year period show an unexplained, increasing, linear time variation with a rate of about 0.05 W m(exp -2) per year. Separate regressions for the periods before and after 1996 January 01 show no unexplained trends but differ substantially in regression parameters. This behavior may reflect a solar source of TSI variations beyond sunspots and faculae but more plausibly results from uncompensated non-solar effects in one or both of the TSI and SPM data sets.

  8. In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions

    NASA Technical Reports Server (NTRS)

    Harris, R.D.; Imaizumi, M.; Walters, R.J.; Lorentzen, J.R.; Messenger, S.R.; Tischler, J.G.; Ohshima, T.; Sato, S.; Sharps, P.R.; Fatemi, N.S.

    2008-01-01

    The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

  9. A new method for assessing surface solar irradiance: Heliosat-4

    NASA Astrophysics Data System (ADS)

    Qu, Z.; Oumbe, A.; Blanc, P.; Lefèvre, M.; Wald, L.; Schroedter-Homscheidt, M.; Gesell, G.

    2012-04-01

    Downwelling shortwave irradiance at surface (SSI) is more and more often assessed by means of satellite-derived estimates of optical properties of the atmosphere. Performances are judged satisfactory for the time being but there is an increasing need for the assessment of the direct and diffuse components of the SSI. MINES ParisTech and the German Aerospace Center (DLR) are currently developing the Heliosat-4 method to assess the SSI and its components in a more accurate way than current practices. This method is composed by two parts: a clear sky module based on the radiative transfer model libRadtran, and a cloud-ground module using two-stream and delta-Eddington approximations for clouds and a database of ground albedo. Advanced products derived from geostationary satellites and recent Earth Observation missions are the inputs of the Heliosat-4 method. Such products are: cloud optical depth, cloud phase, cloud type and cloud coverage from APOLLO of DLR, aerosol optical depth, aerosol type, water vapor in clear-sky, ozone from MACC products (FP7), and ground albedo from MODIS of NASA. In this communication, we briefly present Heliosat-4 and focus on its performances. The results of Heliosat-4 for the period 2004-2010 will be compared to the measurements made in five stations within the Baseline Surface Radiation Network. Extensive statistic analysis as well as case studies are performed in order to better understand Heliosat-4 and have an in-depth view of the performance of Heliosat-4, to understand its advantages comparing to existing methods and to identify its defaults for future improvements. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 218793 (MACC project) and no. 283576 (MACC-II project).

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  11. The Variation of the Solar Diameter and Irradiance:. Eclipse Observation of July 11, 2010

    NASA Astrophysics Data System (ADS)

    Koutchmy, Serge; Bazin, Cyril; Prado, Jean-Yves; Lamy, Philippe; Rocher, Patrick

    2013-03-01

    The variation of the solar diameter is the subject of hot debates due to the possible effect on the Earth climate and also due to different interpretations of long period solar variabilities, including the total irradiance. We shortly review the topic and show that rather long term variations, corresponding to a length well over a solar magnetic cycle, are interesting to consider. The very recently launched mission "Picard" is entirely devoted to the topic but will just permit a short term evaluation. At the time of the last solar total eclipse of 11/7/2010, several experiments were prepared to precisely measure the transit time of the Moon related to the precise value of the solar diameter. Preliminary results coming from the use of a specially designed CNES photometer, put on different atolls of the French Polynesia, are presented. In addition the results of new experiments devoted to fast observations of flash spectra, including their precise chrono-dating, are illustrated and discussed. A new definition of the edge of the Sun, free of spurious scattered light effects strongly affecting all out of eclipse evaluations, is emerging from these observations, in agreement with the most advanced attempts of modeling the outer layers of the photosphere. We also argue for a definite answer concerning the solar diameter measurement from eclipses based on a better precision of lunar profiles coming from lunar altimetry space experiments which will be possible in the following decades.

  12. TIMED GUVI and SEE Observations of Solar Irradiance Variations and the Terrestrial Airglow Response

    NASA Astrophysics Data System (ADS)

    Wolven, B.; Paxton, L.; Morrison, D.; Woods, T.

    2004-12-01

    Since the launch of the TIMED mission in 2001, the SEE and GUVI instruments have observed solar radiance changes during numerous solar flares, and measured their short-term impact on the terrestrial airglow, manifested as changes in both resonantly scattered and photoelectron excited emissions. The continuous coverage and higher time resolution of the GUVI airglow observations, in conjunction with the multispectral (5-color) image format, constitute a unique source of information on the time variation of the solar irradiance in different spectral regions. GUVI limb observations provide additional data on heating and composition changes in the thermosphere in response to these energy inputs. We examine changes in the observed airglow between quiet and flare conditions, and attempt to understand the differences between SEE measurements and the radiances inferred from GUVI airglow data.

  13. [Research on absolute calibration of sun channel of sun photometer using laser raster scanning method].

    PubMed

    Xu, Wen-Bin; Li, Jian-Jun; Zheng, Xiao-Bing

    2013-01-01

    In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3.75%. In the last, the uncertainties of calibration were evaluated and reached to 2.06%. The principle feasibility of the new method was validated. PMID:23586268

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  15. Anomalous effects in silicon solar cell irradiated by 1-MeV protons

    SciTech Connect

    Kachare, R.; Anspaugh, B.E. )

    1989-09-15

    Several silicon solar cells having thicknesses of approximately 63 {mu}m, with and without back-surface fields (BSF), were irradiated with 1-MeV protons having fluences between 10{sup 10} and 10{sup 12} protons/cm{sup 2}. The irradiations were performed using both normal and isotropic incidence on the rear surfaces of the cells. It was observed that after irradiation with fluences greater than 10{sup 11} protons/cm{sup 2}, all BSF cells degraded at a faster rate than cells without BSF. The irradiation results are analyzed using a model in which irradiation-induced defects in the BSF region are taken into account. A number of other possibilities for BSF cell degradation are considered. Tentatively, it is concluded that an increase in defect density due to the formation of aluminum and proton complexes in BSF cells is responsible for the higher-power loss in the BSF cells compared to the non-BSF cells.

  16. Contribution of UVA irradiance to the erythema and photoaging effects in solar and sunbed exposures.

    PubMed

    Sola, Yolanda; Lorente, Jerónimo

    2015-02-01

    Even though UVA irradiance had not been considered detrimental to human skin for years, nowadays it is recognized for its role in photoaging and other biological responses. The ratio UVA/UVB is about 17 at a solar zenith angle (SZA) of 20° and it is almost constant up to 60° when it rapidly increases since the UVB wavelengths (280-320nm) are more attenuated than the UVA waveband (320-400nm). For a constant SZA, the ratio increases with the ozone content. The UVA component of the solar erythemal irradiance ranges from 20% at 20° to 30% at 60°, whereas it varies from 50% to 80% in the two different types of measured sunbeds. Moreover, the different spectral distribution of the lamps used for artificial tanning leads frequently to high UVA doses. The biological responses related to skin photoaging (skin sagging and elastosis) could be around fourfold the equivalent solar irradiance at midday in summer midlatitudes and they can be important in unprotected UVA exposures to sunbeds. The UVA dose accumulated during the time required in reaching 1 minimum erythemal dose (MED) increases with the SZA since the exposure durations are longer. Indeed, seasonal differences in the mean UVA dose are observed due to variations in the ozone content that results in longer exposure times without erythema. Although an artificial tanning session is usually shorter than one hour, the UVA dose from sunbeds during the time for 1 MED for skin type II (250Jm(-2)) can be 2-4 times larger than the solar dose, depending on the lamp spectral emission. PMID:25579807

  17. Solar Irradiance Changes And Photobiological Effects At Earth's Surface Following Astrophysical Ionizing Radiation Events

    NASA Astrophysics Data System (ADS)

    Thomas, Brian; Neale, Patrick

    2016-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth for decades. Although there is some direct biological damage on the surface from redistributed radiation several studies have indicated that the greatest long term threat is from ozone depletion and subsequent heightened solar ultraviolet (UV) radiation. It is known that organisms exposed to this irradiation experience harmful effects such as sunburn and even direct damage to DNA, proteins, or other cellular structures. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In the present work, we employed a radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light). Using biological weighting functions we have considered a wide range of effects, including: erythema and skin cancer in humans; inhibition of photosynthesis in the diatom Phaeodactylum sp. and dinoflagellate Prorocentrum micans inhibition of carbon fixation in Antarctic phytoplankton; inhibition of growth of oat (Avena sativa L. cv. Otana) seedlings; and cataracts. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in

  18. Climate response to changes in atmospheric carbon dioxide and solar irradiance on the time scale of days to weeks

    NASA Astrophysics Data System (ADS)

    Cao, Long; Bala, Govindasamy; Caldeira, Ken

    2012-09-01

    Recent studies show that fast climate response on time scales of less than a month can have important implications for long-term climate change. In this study, we investigate climate response on the time scale of days to weeks to a step-function quadrupling of atmospheric CO2 and contrast this with the response to a 4% increase in solar irradiance. Our simulations show that significant climate effects occur within days of a stepwise increase in both atmospheric CO2 content and solar irradiance. Over ocean, increased atmospheric CO2 warms the lower troposphere more than the surface, increasing atmospheric stability, moistening the boundary layer, and suppressing evaporation and precipitation. In contrast, over ocean, increased solar irradiance warms the lower troposphere to a much lesser extent, causing a much smaller change in evaporation and precipitation. Over land, both increased CO2 and increased solar irradiance cause rapid surface warming that tends to increase both evaporation and precipitation. However, the physiological effect of increased atmospheric CO2 on plant stomata reduces plant transpiration, drying the boundary layer and decreasing precipitation. This effect does not occur with increased solar irradiance. Therefore, differences in climatic effects from CO2 versus solar forcing are manifested within days after the forcing is imposed.

  19. Electrostatic lofting variability of lunar dust under solar wind and solar uv irradiance

    NASA Astrophysics Data System (ADS)

    Cihan Örger, Necmi; Rodrigo Cordova Alarcon, Jose; Cho, Mengu; Toyoda, Kazuhiro

    2016-07-01

    It has been considered that lunar horizon glow is produced by forward scattering of the sunlight above the terminator region by the electrically charged dust grains. Previous lunar missions showed that lunar horizon glow is highly varying phenomenon; therefore, it is required to understand how this physical mechanism fundamentally occurs in order to be able to observe it. Therefore, terminator region and the dayside of the moon are the focus areas of this study in order to explain forward scattering of the sunlight towards night side region in the future steps of this work. In this paper, the results of lunar dust height calculations are presented as a function of solar zenith angle and solar wind properties. First, equilibrium surface potential, Debye length and surface electric field have been calculated to be used in the dust model to predict the lofting of lunar dust under various solar wind conditions. Dependence of the dust lofting on different parameters such as electron temperature or plasma density can be explained from the initial results. In addition, these results showed that zero potential occurs between subsolar point and terminator region as it is expected, where the maximum height of dust particles are minimum, and its position changes according to the solar wind properties and photoemission electron temperature. Relative to this work, a CubeSat mission is currently being developed in Kyushu Institute of Technology to observe lunar horizon glow.

  20. Are the most recent estimates for Maunder Minimum solar irradiance in agreement with temperature reconstructions?

    NASA Astrophysics Data System (ADS)

    Feulner, Georg

    2011-08-01

    Estimates for the total solar irradiance (TSI) during the 17th-century Maunder Minimum published in the last few years have pointed towards a TSI difference of 0.2-0.7 W m-2 as compared to the 2008/2009 solar minimum. Two recent studies, however, give anomalies which differ from this emerging consensus. The first study indicates an even smaller TSI difference, placing the Maunder Minimum TSI on the same level as the 2008/2009 minimum. The second study on the other hand suggests a very large TSI difference of 5.8 W m-2. Here I use coupled climate simulations to assess the implications of these two estimates on Northern-hemisphere surface air temperatures over the past millennium. Using a solar forcing corresponding to the estimate of the first study, simulated Northern-hemisphere temperatures over the past millennium are consistent with reconstructed surface air temperatures. The large TSI differences between times of high and low solar activity as suggested by the second study, however, yield temperatures during all past grand solar minima that are too low, an excessive variance in Northern-hemisphere temperature on timescales of 50-100 years as compared to reconstructions, and temperatures during the first half of the 20th century which are too low and inconsistent with the instrumental temperature record. In summary this suggests a more moderate TSI difference of less than 1 W m-2 and possibly as low as 0-0.3 W m-2.

  1. A simple analytical formula to compute clear sky total and photosynthetically available solar irradiance at the ocean surface

    NASA Technical Reports Server (NTRS)

    Frouin, Robert; Lingner, David W.; Gautier, Catherine; Baker, Karen S.; Smith, Ray C.

    1989-01-01

    A simple but accurate analytical formula was developed for computing the total and the photosynthetically available solar irradiances at the ocean surface under clear skies, which takes into account the processes of scattering by molecules and aerosols within the atmosphere and of absorption by the water vapor, ozone, and aerosols. These processes are parameterized as a function of solar zenith angle, aerosol type, atmospheric visibility, and vertically integrated water-vapor and ozone amounts. Comparisons of the calculated and measured total and photosynthetically available solar irradiances for several experiments in tropical and mid-latitude ocean regions show 39 and 14 Wm/sq m rms errors (6.5 and 4.7 percent of the average measured values) on an hourly time scale, respectively. The proposed forumula is unique in its ability to predict surface solar irradiance in the photosynthetically active spectral interval.

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

  3. Robustly photogenerating H2 in water using FeP/CdS catalyst under solar irradiation.

    PubMed

    Cheng, Huanqing; Lv, Xiao-Jun; Cao, Shuang; Zhao, Zong-Yan; Chen, Yong; Fu, Wen-Fu

    2016-01-01

    Photosplitting water for H2 production is a promising, sustainable approach for solar-to-chemical energy conversion. However, developing low-cost, high efficient and stable photocatalysts remains the major challenge. Here we report a composite photocatalyst consisting of FeP nanoparticles and CdS nanocrystals (FeP/CdS) for photogenerating H2 in aqueous lactic acid solution under visible light irradiation. Experimental results demonstrate that the photocatalyst is highly active with a H2-evolution rate of 202000 μmol h(-1) g(-1) for the first 5 h (106000 μmol h(-1) g(-1) under natural solar irradiation), which is the best H2 evolution activity, even 3-fold higher than the control in situ photo-deposited Pt/CdS system, and the corresponding to an apparent quantum efficiency of over 35% at 520 nm. More important, we found that the system exhibited excellent stability and remained effective after more than 100 h in optimal conditions under visible light irradiation. A wide-ranging analysis verified that FeP effectively separates the photoexcited charge from CdS and showed that the dual active sites in FeP enhance the activity of FeP/CdS photocatalysts. PMID:26818001

  4. Robustly photogenerating H2 in water using FeP/CdS catalyst under solar irradiation

    PubMed Central

    Cheng, Huanqing; Lv, Xiao-Jun; Cao, Shuang; Zhao, Zong-Yan; Chen, Yong; Fu, Wen-Fu

    2016-01-01

    Photosplitting water for H2 production is a promising, sustainable approach for solar-to-chemical energy conversion. However, developing low-cost, high efficient and stable photocatalysts remains the major challenge. Here we report a composite photocatalyst consisting of FeP nanoparticles and CdS nanocrystals (FeP/CdS) for photogenerating H2 in aqueous lactic acid solution under visible light irradiation. Experimental results demonstrate that the photocatalyst is highly active with a H2-evolution rate of 202000 μmol h−1 g−1 for the first 5 h (106000 μmol h−1 g−1 under natural solar irradiation), which is the best H2 evolution activity, even 3-fold higher than the control in situ photo-deposited Pt/CdS system, and the corresponding to an apparent quantum efficiency of over 35% at 520 nm. More important, we found that the system exhibited excellent stability and remained effective after more than 100 h in optimal conditions under visible light irradiation. A wide-ranging analysis verified that FeP effectively separates the photoexcited charge from CdS and showed that the dual active sites in FeP enhance the activity of FeP/CdS photocatalysts. PMID:26818001

  5. Robustly photogenerating H2 in water using FeP/CdS catalyst under solar irradiation

    NASA Astrophysics Data System (ADS)

    Cheng, Huanqing; Lv, Xiao-Jun; Cao, Shuang; Zhao, Zong-Yan; Chen, Yong; Fu, Wen-Fu

    2016-01-01

    Photosplitting water for H2 production is a promising, sustainable approach for solar-to-chemical energy conversion. However, developing low-cost, high efficient and stable photocatalysts remains the major challenge. Here we report a composite photocatalyst consisting of FeP nanoparticles and CdS nanocrystals (FeP/CdS) for photogenerating H2 in aqueous lactic acid solution under visible light irradiation. Experimental results demonstrate that the photocatalyst is highly active with a H2-evolution rate of 202000 μmol h-1 g-1 for the first 5 h (106000 μmol h-1 g-1 under natural solar irradiation), which is the best H2 evolution activity, even 3-fold higher than the control in situ photo-deposited Pt/CdS system, and the corresponding to an apparent quantum efficiency of over 35% at 520 nm. More important, we found that the system exhibited excellent stability and remained effective after more than 100 h in optimal conditions under visible light irradiation. A wide-ranging analysis verified that FeP effectively separates the photoexcited charge from CdS and showed that the dual active sites in FeP enhance the activity of FeP/CdS photocatalysts.

  6. Results of 1 MeV proton irradiation of front and back surfaces of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Kachare, R.; Weizer, V. G.

    1987-01-01

    Several silicon solar cells with and without back surface fields (BSF), having thicknesses of 200 microns and 63 microns were irradiated with 1 MeV protons having fluences between 1 times 10 to the 10th power and 1 times 10 to the 12th power p/square cm. The irradiation was performed using both normal and isotropic incidence on the front as well as back surfaces of the solar cells. The results of the back surface irradiations are analyzed using a model in which irradiation induced defects across the high-low (BSF) junction are considered. It is concluded that degradation of the high-low junction is responsible for the severe performance loss in thinner cells when irradiated from the rear.

  7. Correlation between total solar irradiance and global land temperatures for the last 120 years

    NASA Astrophysics Data System (ADS)

    Varonov, A.; Shopov, Y. Y.

    2016-02-01

    We analyze the solar impact on one of the main Earth climate system components—the land-near-surface air temperature—during the past 120 years. Using statistical analysis, a correlation between the variations of the total solar irradiance and of the annual-mean land-near-surface air temperatures was found. An unknown time lag between both data sets was expected to be present due to the complexity of the Earth's climate system leading to a delayed response to changes in influencing factors. We found the best correlation with coefficient over 90% for a 14-year shift of the annual mean land temperature record ahead with data before 1970, while the same comparison with data until 2006 yields 61% correlation. These results show the substantially higher influence of the total solar irradiance on the global land temperatures before 1970. The decline of this influence during the last 40 years could be attributed to the increasing concentration of anthropogenic greenhouse gases in the Earth's atmosphere.

  8. On the Importance of the Flare's Late Phase for the Solar Extreme Ultraviolet Irradiance

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Eparvier, Frank; Jones, Andrew R.; Hock, Rachel; Chamberlin, Phillip C.; Klimchuk, James A.; Didkovsky, Leonid; Judge, Darrell; Mariska, John; Bailey, Scott; Tobiska, W. Kent; Schrijver, Carolus J.; Webb, David F.; Warren, Harry

    2011-01-01

    The new sol