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1

Extraterrestrial Spectral Solar Irradiance Data for Modeling Spectral Solar Irradiance at the Earth's Surface.  

National Technical Information Service (NTIS)

This report describes the extraterrestrial (air mass zero, AMO) spectral solar irradiance data used by the Solar Energy Research Institute's Resource Assessment Branch in models to calculate spectral solar irradiance at the earth's surface. The report con...

C. Riordan

1987-01-01

2

Extraterrestrial solar spectral irradiance during a solar eclipse  

Microsoft Academic Search

A theoretical model of solar irradiance at the top of the atmosphere during an eclipse is presented and compared with ground-based broadband data. Data taken during annular, partial and total eclipses are compared with model predictions, which are based on a spectrally degraded version of a 168 wavelength model developed by the World Radiation Center in 1983. Both the model

J. E. Tansil

1986-01-01

3

Ground-based determination of the spectral ultraviolet extraterrestrial solar irradiance: Providing a link between space-based and ground-based solar UV measurements  

NASA Astrophysics Data System (ADS)

The extraterrestrial solar spectrum between 295 and 355 nm has been determined from direct irradiance measurements made with a Brewer double spectrophotometer, using the Langley method. The measurements in this study consist of 449 half days of data collected during 1998 at Mauna Loa Observatory, Hawaii. The +/-2.3% accuracy of this extraterrestrial solar spectrum is obtained by a careful investigation of the instrument calibration and the systematic errors that can arise because of atmospheric and instrument instabilities as well as finite slit width effects and is limited by the uncertainty of the absolute irradiance scale transfer between the standard laboratory and the instrument. A comparison between this extraterrestrial solar spectrum measured from the ground with the mean UARS and ATLAS-1 spectrum show an agreement better than 3%. The mean ratios are 1.002 for the mean UARS spectrum, 1.003 for the mean ATLAS-1 spectrum, 1.013 for the SOLSPEC spectrum, and 1.017 for the ATLAS-3 spectrum.

Gröbner, J.; Kerr, J. B.

2001-04-01

4

Data on total and spectral solar irradiance  

NASA Technical Reports Server (NTRS)

This paper presents a brief survey of the data available on solar constant and extraterrestrial solar spectral irradiance. The spectral distribution of solar radiation at ground surface, computed from extraterrestrial solar spectral irradiance for several air mass values and for four levels of atmospheric pollution, is also presented. The total irradiance at ground level is obtained by integration of the area under the spectral irradiance curves. It is significant that, as air mass increases or as turbidity increases, the amount of energy in the infrared relative to the total increases and that the energy in the UV and visible decreases.

Mecherikunnel, A. T.; Gatlin, J. A.; Richmond, J. C.

1983-01-01

5

Extraterrestrial intelligence in the Solar System - Resolving the Fermi Paradox  

Microsoft Academic Search

The assertion that extraterrestrial intelligences (ETI) do not exist, based on the apparent contradictions inherent in the Fermi Paradox, rests upon an unproven and untenable presumption: that ETI are not now present in the Solar System. The current observational status of the Solar System is insufficient to support the assumption that ETI are not here. Most advanced civilizations also would

R. A. Freitas Jr.

1983-01-01

6

Extraterrestrial applications of solar optics for interior illumination  

NASA Technical Reports Server (NTRS)

Solar optics is a terrestrial technology that has potential extraterrestrial applications. Active solar optics (ASO) and passive solar optics (PSO) are two approaches to the transmission of sunlight to remote interior spaces. Active solar optics is most appropriate for task illumination, while PSO is most appropriate for general illumination. Research into solar optics, motivated by energy conservation, has produced lightweight and low-cost materials, products that have applications to NASA's Controlled Ecological Life Support System (CELSS) program and its lunar base studies. Specifically, prism light guides have great potential in these contexts. Several applications of solar optics to lunar base concepts are illustrated.

Eijadi, David A.; Williams, Kyle D.

1992-01-01

7

Calibration of EOS multispectral imaging sensors and solar irradiance variability  

NASA Technical Reports Server (NTRS)

Earth Observation System (EOS) optical multispectral imaging sensors provide images of the earth at various spectral and spatial resolutions, in the visible (VIS) and infrared (IR) regions of the solar spectrum. Accurate knowledge of extraterrestrial solar spectral irradiance and its variations with time, are needed to trace sensor calibration in space, and for the development of terrestrial atmospheric models needed in data validation. A brief review of the extraterrestrial solar VIS/IR spectral irradiance available in the literature will be reviewed, and the need to develop an extraterrestrial solar spectral irradiance for the EOS studies will be pointed out. The solar calibration of the Earth Radiation Budget Experiments (ERBE), earth-viewing sensors will be discussed. Observed variations in the solar constant (solar irradiance, at the mean sun-earth distance of one astronomical unit, integrated over all wavelengths), and solar spectral irradiance with solar activity and its implications for EOS studies also will be discussed.

Mecherikunnel, Ann

1991-01-01

8

Mechanistical Studies on the Irradiation of Methanol in Extraterrestrial Ices  

NASA Astrophysics Data System (ADS)

Pure ices of amorphous methanol, CH3OH(X1A'), were irradiated at 11 K by 5 keV electrons at 100 nA for 1 hr. These energetic electrons simulate electronic energy transfer processes that occur as interstellar ices, comets, and icy solar system bodies are subjected to irradiation from MeV ions and secondary electrons produced in this process. The results were analyzed quantitatively via absorption-reflection-absorption Fourier transform infrared (FTIR) spectroscopy, with the identification of new species aided by high-level electronic structure calculations. The unimolecular decomposition of methanol was found to proceed via the formation of (1) the hydroxymethyl radical, CH2OH(X2A''), and atomic hydrogen, H(2S1/2), (2) the methoxy radical, CH3O(X2A'), plus atomic hydrogen, (3) formaldehyde, H2CO(X1A1) plus molecular hydrogen, H2(X1?+g), and (4) the formation of methane, CH4(X1A1), together with atomic oxygen, O(1D). The accessibility of the last channel indicates that the reverse process, oxygen addition into methane to form methanol, should also be feasible. A kinetic model is presented for the decomposition of methanol into these species, as well as the formyl radical, HCO(X2A'), and carbon monoxide, CO(X1?+). During the subsequent warming up of the sample, radicals previously generated within the matrix were mobilized and found to recombine to form methyl formate, CH3OCHO(X1A'), glycolaldehyde, CH2OHCHO(X1A'), and ethylene glycol, HOCH 2CH2OH(X1A). Upper limits for the production of these species by the recombination of neighboring radicals produced during irradiation as well as during the warm-up procedure are presented. The generation of these molecules by irradiation of ices in the solid state and their subsequent sublimation into the gas phase can help explain their high abundances as observed toward hot molecular cores and underlines their importance in astrobiology.

Bennett, Chris J.; Chen, Shih-Hua; Sun, Bing-Jian; Chang, Agnes H. H.; Kaiser, Ralf I.

2007-05-01

9

A Model for Extraterrestrial Solar Degradation of Zinc Oxide  

Microsoft Academic Search

Discoloration of ZnO from ultraviolet absorption can be produced in the laboratory, but is most severe in extraterrestrial environments, when microcrystalline ZnO is used as a pigment for spacecraft thermal control surfaces. Understanding of this degradation process should lead to development of pigments with improved thermal stability under prolonged ultraviolet exposure. It is noted that movement of photoexcited holes to

J. S. Blakemore

1966-01-01

10

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials  

PubMed Central

Cosmochemistry is the chemical analysis of extraterrestrial materials. This term generally is taken to mean laboratory analysis, which is the cosmochemistry gold standard because of the ability for repeated analysis under highly controlled conditions using the most advanced instrumentation unhindered by limitations in power, space, or environment. Over the past 40 y, advances in technology have enabled telescopic and spacecraft instruments to provide important data that significantly complement the laboratory data. In this special edition, recent advances in the state of the art of cosmochemistry are presented, which range from instrumental analysis of meteorites to theoretical–computational and astronomical observations.

MacPherson, Glenn J.; Thiemens, Mark H.

2011-01-01

11

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials.  

PubMed

Cosmochemistry is the chemical analysis of extraterrestrial materials. This term generally is taken to mean laboratory analysis, which is the cosmochemistry gold standard because of the ability for repeated analysis under highly controlled conditions using the most advanced instrumentation unhindered by limitations in power, space, or environment. Over the past 40 y, advances in technology have enabled telescopic and spacecraft instruments to provide important data that significantly complement the laboratory data. In this special edition, recent advances in the state of the art of cosmochemistry are presented, which range from instrumental analysis of meteorites to theoretical-computational and astronomical observations. PMID:22128323

MacPherson, Glenn J; Thiemens, Mark H

2011-11-29

12

The total and spectral solar irradiance and its possible variations  

NASA Technical Reports Server (NTRS)

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.

Thekaekara, M. P.

1975-01-01

13

Distributed modeling of extraterrestrial solar radiation over the rugged terrains of Pakistan  

Microsoft Academic Search

In Pakistan, the solar analogue has been addressed but its surface geographical parameterization has given least attention.\\u000a Inappropriate density of stations and their spatial coverage particularly in difficult peripheral national territories, little\\u000a or no solar radiation data, nonsatisfactory sunshine hours data, and low quality of ground observed cloud cover data create\\u000a a situation in which the spatial modeling of Extraterrestrial

Romana Ambreen; Xinfa Qiu; Iftikhar Ahmad

2011-01-01

14

The effect of irradiation on the magnetic properties of rock and synthetic samples with implications to irradiation of extraterrestrial materials in space  

NASA Astrophysics Data System (ADS)

Before reaching the Earth through meteorite falls or sample return, most extraterrestrial materials have been exposed to space radiations at different stages in their history. In the Solar System there are three main types of particle radiation: large fluxes of low-energy solar wind (SW) particles, smaller fluxes of high-energy galactic-cosmic-ray (GCR) particles, and intermittent intense fluxes of solar-flare-associated particles, also called solar cosmic rays or solar energetic particles (SEP). We report here the results of laboratory analog experiments to consider the potential effects of SEP and GCR on the magnetic properties of extraterrestrial materials. We carried out proton bombardment experiments (with irradiation energies E1=400 keV and E2=850 keV and three irradiation fluences in 1014-1016 p/cm2 range) and lead-ion bombardment experiments (E=1 GeV) on (previously demagnetized by 120 mT alternating magnetic field) rock and synthetic samples with the following magnetic carriers: metallic iron and nickel iron, Ti-rich and Ti-free magnetite, pyrrhotite. Irradiation experiments resulted in either further demagnetization or magnetization of irradiated samples depending on the type of magnetic mineralogy and type of ionizing radiation involved. Apart for the formation of radiation-induced remanent magnetization (RIRM), we observed major changes in bulk magnetic properties, i.e., a moderate to dramatic decrease (up to 93%) in the coercivity of remanence Bcr for all iron-bearing phases (iron-in-epoxy and Bensour meteorite samples). Contrary to iron-bearing samples, several magnetite-bearing samples experienced a radiation-induced magnetic hardening (increase in Bcr). Magnetic hardening was also observed for Ar2+ ion-irradiated nickel iron-bearing HED meteorites, measured for comparison with the previously stated results. Therefore, the combined effect of SEP with GCR may magnetically soften iron-bearing materials and harden magnetite-bearing materials. In order to answer the question weather RIRM may account for natural remanent magnetization of meteorites and lunar samples, physical mechanism of RIRM formation and potential dependence of RIRM intensity on the background magnetic field present during irradiation event should be investigated.

Bezaeva, N. S.; Gattacceca, J.; Rochette, P.; Duprat, J.; Rizza, G.; Vernazza, P.; Trukhin, V. I.

2013-05-01

15

Solar Cycle Variation in Solar Irradiance  

NASA Astrophysics Data System (ADS)

The correlation between solar irradiance and the 11-year solar activity cycle is evident in the body of measurements made from space, which extend over the past four decades. Models relating variation in solar irradiance to photospheric magnetism have made significant progress in explaining most of the apparent trends in these observations. There are, however, persistent discrepancies between different measurements and models in terms of the absolute radiometry, secular variation and the spectral dependence of the solar cycle variability. We present an overview of solar irradiance measurements and models, and discuss the key challenges in reconciling the divergence between the two.

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

2014-07-01

16

Enantiomeric Excesses Induced in Amino Acids by Ultraviolet Circularly Polarized Light Irradiation of Extraterrestrial Ice Analogs: A Possible Source of Asymmetry for Prebiotic Chemistry  

NASA Astrophysics Data System (ADS)

The discovery of meteoritic amino acids with enantiomeric excesses of the L-form (ee L) has suggested that extraterrestrial organic materials may have contributed to prebiotic chemistry and directed the initial occurrence of the ee L that further led to homochirality of amino acids on Earth. A proposed mechanism for the origin of ee L in meteorites involves an asymmetric photochemistry of extraterrestrial ices by UV circularly polarized light (CPL). We have performed the asymmetric synthesis of amino acids on achiral extraterrestrial ice analogs by VUV CPL, investigating the chiral asymmetry transfer at two different evolutionary stages at which the analogs were irradiated (regular ices and/or organic residues) and at two different photon energies (6.6 and 10.2 eV). We identify 16 distinct amino acids and precisely measure the L-enantiomeric excesses using the enantioselective GC × GC-TOFMS technique in five of them: ?-alanine, 2,3-diaminopropionic acid, 2-aminobutyric acid, valine, and norvaline, with values ranging from ee L = -0.20% ± 0.14% to ee L = -2.54% ± 0.28%. The sign of the induced ee L depends on the helicity and the energy of CPL, but not on the evolutionary stage of the samples, and is the same for all five considered amino acids. Our results support an astrophysical scenario in which the solar system was formed in a high-mass star-forming region where icy grains were irradiated during the protoplanetary phase by an external source of CPL of a given helicity and a dominant energy, inducing a stereo-specific photochemistry.

Modica, Paola; Meinert, Cornelia; de Marcellus, Pierre; Nahon, Laurent; Meierhenrich, Uwe J.; Le Sergeant d'Hendecourt, Louis

2014-06-01

17

Solar irradiance spectrum at Madrid  

NASA Astrophysics Data System (ADS)

An experimental study of the spectrum of direct solar irradiance in Madrid on dear days has been made. The expression I(?) = (1/S)I 0(?)exp(-?)sec? s){(cos? s)[1 + sec? s(0.13 ?/? 1.5)]} is proposed to describe more realistically the real direct solar spectral irradiance in Madrid.

Pons, A.; Corróns, A.

18

The alteration of organic matter in response to ionising irradiation: Chemical trends and implications for extraterrestrial sample analysis  

NASA Astrophysics Data System (ADS)

Ionising radiation is an energy source capable of generating and altering complex organic matter. A full understanding of the radiolytic formation and evolution of organic matter is essential to appreciate the budget of organic chemicals that exist in cometary and interstellar ices, carbonaceous meteorites, and to understand the results of analyses of irradiated extraterrestrial organic matter, such as that in cometary nuclei. The effects of ionising radiation on a set of 10 naturally occurring, terrestrial organic assemblages have been revealed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), carbon isotopic analysis, and stepped combustion-isotope ratio mass spectrometry (SC-IRMS). Progressive radiolytic alteration of biogenic complex-hydrocarbon mixtures induces a decrease in the average size and extent of alkylation of polyaromatic hydrocarbons (PAH) and an increase in the abundance of oxygen-containing compounds, as indicated by Py-GC-MS, and an enrichment in 13C. These changes are attributed to reactions with free radicals, produced by ionising radiation. In contrast, the progressive radiolytic alteration of bitumens proposed to have derived from the radiolytic polymerisation of methane into an organic solid produces, upon pyrolysis, PAH of increasing average size and degree of alkylation. This, the opposite of the trend observed in the irradiated complex-hydrocarbons mixtures, cannot be explained in terms of the radiolytic alteration of a pre-existing array of complex organic molecules. Instead, it suggests the gradual construction of PAH from smaller molecules, supporting the hypothesis of a methane origin. Radiolytic alteration is also associated with a previously unrecognised increase in the mean combustion temperature of organic matter. This leads to predictions regarding the combustion characteristics of the irradiated organic matter present on cometary nuclei. A full understanding of the relationship between the combustion characteristics of organic polymers, radiation dose and the atomic H/C ratio should lead to the better design and implementation of in situ extraterrestrial sample analysis hardware and aid the interpretation of data from such missions. This study establishes predictable organic chemical responses of organic matter, upon exposure to ionising radiation. Our results support proposals that extraterrestrial PAH may be formed by the cosmic irradiation of simple hydrocarbons in interstellar ices. Our data may also be relevant to analogous material formed in other hydrocarbon-rich environments, such as the surface and atmosphere of Titan and other icy bodies, such as comets, and to the results of in situ analyses of extraterrestrial organic matter.

Court, Richard W.; Sephton, Mark A.; Parnell, John; Gilmour, Iain

2006-02-01

19

Solar Spectral Irradiance and Climate  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

20

Solar Irradiation over Zambia.  

National Technical Information Service (NTIS)

Angstroem-Page linear regression equation between global irradiation and sunshine duration is fitted for five Zambian locations for which the direct measured values of the global irradiation exist. Excellent correlation is found to exist for all the five ...

P. C. Jain

1983-01-01

21

Status of knowledge of the extraterrestrial solar 'constant' and spectral distribution  

NASA Technical Reports Server (NTRS)

Current knowledge of the total solar flux (the solar constant) and its spectral distribution at the top of the earth's atmosphere is reviewed. The development of pyrheliometers and radiation scales is traced, noting that active cavity pyrheliometers have been developed to reduce measurement uncertainty to within 0.1/%. The weighted mean solar constant from ground-based, aircraft, balloon, spacecraft and sounding rocket observations has been calculated to be 1369 W/sq m. Future observations are planned in order to reduce uncertainty to the 0.1% level required for climatological studies. A comparison of the measurement and models of solar spectral irradiance obtained by Thekaekara (1969, 1974), Arvesen (1969) and Labs and Neckel (1968, 1975) shows that the spectrum of Labs and Neckel is most accurate in the 0.4 to 1.25 micron range, that of Arvesen is best in the 0.3 to 0.4 abd 1.25 to 2.5 micron ranges and the model of Labs and Neckel is best at wavelengths greater than 2.5 microns.

Willson, R. C.

1978-01-01

22

Diffuse and global solar spectral irradiance under cloudless skies  

SciTech Connect

A simple empirical model to calculate solar spectral diffuse and global irradiance under cloudless skies was investigated. This formulation takes into account absorption of radiation by molecules such as O/sub 3/, H/sub 2/O and the uniformly-mixed absorbing gases CO/sub 2/ and O/sub 2/. Attenuation by Rayleigh-scattering and aerosol extinction are included. Aerosol attenuation is calculated through Angstroem's turbidity parameters ..cap alpha.. and ..beta... The diffuse radiation is assumed to be composed of three parts: (1) Rayleigh-scattered diffuse irradiance; (2) aerosol-scattered diffuse irradiance; and (3) irradiance arising out of multiple reflections between the atmosphere and the ground. The global irradiance is the sum of these three components of diffuse irradiance plus the direct irradiance. The input parameters include an extraterrestrial spectrum, zenith angle theta, turbidity coefficient ..beta.., wavelength exponent ..cap alpha.., ground albedo rho/sub g/, water vapor content and ozone content. The model is shown to yield very good results up to air mass two when compared to accurate theoretical calculations. No comparisons with measured spectra are presented because of a lack of accurate specifications of the input parameters. Results are presented to show the effect of variation of certain of the input parameters.

Brine, D.T.; Iqbal, M.

1982-01-01

23

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

NASA Astrophysics Data System (ADS)

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 proxy models of solar irradiance variability, compares the observed and modeled irradiance variations on multiple time scales, and illustrates terrestrial applications of solar irradiance variability models.

Lean, J.

2013-12-01

24

SORCE Solar Irradiance Data Products  

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado manages the SOlar Radiation and Climate Experiment (SORCE) Science Data System. This data processing system routinely produces Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI) data products, which are formulated using measurements from the four primary instruments on board the SORCE spacecraft. The TIM instrument provides measurements of the TSI, whereas the SIM, SOLSTICE, and XPS instruments collectively provide measurements of the solar irradiance spectrum from 1 nm to 2400 nm (excluding 31-115 nm, which is measured by the SEE instrument on NASA's TIMED mission). Derived products, such as the Magnesium II Core-to-Wing Index which can be used for space weather applications, are also produced. The SORCE Science Data System utilizes raw spacecraft and instrument telemetry, calibration data, and other ancillary information to produce a variety of solar irradiance data products that have been corrected for all known instrumental and operational factors. Since launch of the SORCE spacecraft in January 2003, science processing algorithms have continued to mature, instrument calibrations (e.g. degradation corrections) have improved, and regularly updated versions of data products have been released. "Level 3" data products (time-averaged over daily and six-hourly periods and/or spectrally re-sampled onto uniform wavelength scales) are routinely produced and delivered to the public via the SORCE web site (http://lasp.colorado.edu/sorce/data/), and are archived at the Goddard Earth Sciences (GES) Data and Information Services Center (DISC). Native resolution "Level 2" products are also available for scientific studies. This poster provides an overview of the SORCE data processing system, summarizes the present state of the processing algorithms, describes the quality of the current SORCE data products, provides details on how to access SORCE science data, and presents future plans.

Lindholm, D. M.; Pankratz, C. K.; Knapp, B. G.; Meisner, R.; Fontenla, J.; Harder, J. W.; McClintock, W. E.; Kopp, G.; Snow, M.; Woods, T. N.

2008-12-01

25

Updates to ISO 21348 (determining solar irradiances)  

NASA Astrophysics Data System (ADS)

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 simulation, ii) material degradation, and iii) the development of lamps and filters for terrestrial solar simulators. A solar irradiance product certifies compliance with this process-based standard by following compliance criteria that are described in this International Standard.

Tobiska, W. Kent

2012-07-01

26

Extraterrestrial imperative  

NASA Technical Reports Server (NTRS)

The future benefits of extraterrestrial space to man and his problems, both personal and environmental, are discussed. Particular attention was given to space manufacturing, development of space power plants, mineral exploration, and transportation costs of such activities.

Ehricke, K. A.

1972-01-01

27

Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

28

Rethinking satellite-based solar irradiance modelling  

Microsoft Academic Search

Accurate solar irradiance data are not only of particular importance for the assessment of the radiative forcing of the climate system, but also absolutely necessary for efficient planning and operation of solar energy systems. Within the European project Heliosat-3, a new type of solar irradiance scheme is developed. This new type will be based on radiative transfer models (RTM) using

R. W. Mueller; K. F. Dagestad; P. Ineichen; M. Schroedter-Homscheidt; S. Cros; D. Dumortier; R. Kuhlemann; J. A. Olseth; G. Piernavieja; C. Reise; L. Wald; D. Heinemann

2004-01-01

29

RETHINKING SATELLITE BASED SOLAR IRRADIANCE MODELLING  

Microsoft Academic Search

Accurate solar irradiance data are not only of particular importance for the assessment of the radiative forcing of the climate system, but also absolutely necessary for an efficient planning and operation of solar energy systems. Within the European project Heliosat-3 a new type of solar irradiance scheme is developed. This new type will be based on radiative transfer models (RTM)

R. W. Mueller; K. F. Dagestad; R. Kuhlemann; J. A. Olseth; C. Reise; M. Schroedter; L. Wald; D. Heinemann

30

The Solar EUV Irradiance: New Insights  

NASA Astrophysics Data System (ADS)

A key to understanding variability in the Earth's atmosphere is understanding the variability in the solar irradiance that is a primary source of energy into the Earth system. Variations in this input drive variability in different atmospheric regions depending on where solar photons of particular wavelengths are absorbed. Of particular interest to the TIGER community is the solar extreme ultraviolet (EUV) irradiance that creates the ionosphere and heats the thermosphere. The ten-year record of solar spectral irradiance in the extreme ultraviolet (EUV) from Solar EUV Experiment (SEE) on NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission, now continued at higher spectral and temporal resolution by the EUV Variability Experiment (EVE) on NASA's Solar Dynamics Observatory (SDO) provide us with an excellent set of well-calibrated data with which to study the variability of the important solar EUV spectral irradiance on timescales of the solar cycle, solar rotation, and now flares, and how it impacts the Earth's atmospheric variability.

Eparvier, Francis

2012-07-01

31

ISO 21348 - Process for determining solar irradiances  

NASA Astrophysics Data System (ADS)

A new international standard is being published by the International Standards Organization ISO The document ISO 21348 Space Environment natural and artificial -- Process for determining solar irradiances describes the process for representing solar irradiances We report on the content of the final version of this new standard Because solar irradiance measurements and modeling are constantly evolving through improved instrumentation measurement techniques and modeling capabilities the new standard has been written as a process-based standard to encourage development in solar irradiance determination The standard covers all representations of solar irradiances and is applicable to measurements reference spectra empirical models physics-based models as well as solar proxies and indices The purpose of the standard is to provide a common specification for all solar irradiances for use by space systems materials and environment users A solar irradiance product or specification is compliant with the standard if four criteria are followed First solar irradiances are reported at the minimum in SI units of Watts per square meter corrected to 1 AU Second the method of determining irradiances is documented for data collection processing archiving validation accuracy precision methodology and algorithm information Where applicable a description of proxies and independent data sets used in the derivation of empirical models including the rationale for proxy selection and the mathematical formulation for numerical models is

Tobiska, W.; Nusinov, A.

32

Extraterrestrial Life  

NASA Technical Reports Server (NTRS)

Extraterrestrial Intelligence is intelligent life that developed somewhere other than the earth. Such life has not yet been discovered. However, scientific research, including astronomy, biology, planetary science and studies of fossils here on earth have led many scientists to conclude that such life may exist on planets orbiting at least some of the hundreds of billions of stars in our Milky Way Galaxy. Today, some researchers are trying to find evidence for extraterrestrial intelligence. This effort is often called SETI, which stands for Search for Extraterrestrial Intelligence. SETI researchers decided that looking for evidence of their technology might be the best way to discover other intelligent life in the Galaxy. They decided to use large radio telescopes to search the sky over a wide range of radio frequencies...

Klein, M. J.

1993-01-01

33

Historical Variations in Solar UV Irradiance  

NASA Astrophysics Data System (ADS)

Satellite measurements of solar UV variability have been made by at least fifteen different instruments since 1978. While it is difficult to keep a single UV irradiance instrument operating throughout a complete solar cycle, many of these instruments (Nimbus-7 SBUV, SME, NOAA-9 SBUV/2, NOAA-11 SBUV/2, UARS SUSIM, UARS SOLSTICE) were able to observe both maximum and minimum irradiance levels during either rising or declining phases of solar activity. Comparisons of these published results for solar cycles 21, 22, and 23 show consistent solar cycle irradiance changes at key wavelengths for terrestrial effects (e.g. 205 nm, 240 nm) within instrumental uncertainties. All historical data sets also show the same relative spectral dependence in the ultraviolet for both short-term (rotational) and long-term (solar cycle) variations. Empirical solar irradiance models that employ multiple proxy data sets to represent spectral irradiance produce long-term solar UV variations that are in good agreement with merged observational data through 2005. Recent UV irradiance data from the SORCE mission covering the declining phase of Cycle 23 present a different picture of long-term solar variations, with significantly larger temporal changes and different spectral dependence. We present comparisons of the SORCE irradiance data with previous solar UV observations and current model predictions. Scaling factors for use with solar UV proxy indexes have been derived from SORCE SIM and SORCE SOLSTICE data during 2004-2005. These scale factors, based on short-term irradiance variations, agree very well with results derived from concurrent NOAA-17 SBUV/2 and UARS SUSIM measurements. The 2004-2005 scale factors are consistent with previously derived scale factors that produce calculated long-term irradiance changes in good agreement with observations. The SORCE long-term solar UV irradiance results, corresponding to the early part of the mission, are consistent with undercorrection of instrument response changes during the first few years of SORCE measurements.

DeLand, M. T.

2011-12-01

34

Life on other worlds : the twentieth century extraterrestrial life debate  

NASA Astrophysics Data System (ADS)

List of illustrations; List of tables; Acknowledgements; Introduction; 1. From the physical world to the biological universe: Democritus to Lowell; 2. Life in the solar system; 3. Solar systems beyond; 4. Extraterrestrials in literature and the arts: the role of imagination; 5. The UFO controversy and the extraterrestrial hypothesis; 6. The origin and evolution of life in the extraterrestrial context; 7. SETI: the search for extraterrestrial intelligence; 8. The meaning of life; 9. Summary and conclusion: the biological universe; Select bibliographical essay; Index.

Dick, Steven J.

1998-12-01

35

TSIS: The Total Solar Irradiance Sensor  

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

36

An introduction to solar radiation  

Microsoft Academic Search

This book was written for energy analysts, designers of thermal devices, photovoltaic engineers, architects, agronomists, and hydrologists who must calculate an amount of solar radiation incident on a surface. Includes reading lists, diagrams, a subject index and tables with useful data. Contents, abridged: Sun-earth astronomical relationship. The solar constant and its spectral distribution. Extraterrestrial solar irradiation. Solar spectral radiation under

M. Iqbal

1983-01-01

37

The search for extraterrestrial artifacts (SETA)  

NASA Astrophysics Data System (ADS)

The Artifact Hypothesis states that an advanced extraterrestrial intelligence has undertaken a long-term program of galactic exploration via the transmission of material artifacts. An attempt to verify this hypothesis experimentally, the search for extraterrestrial artifacts (SETA), is proposed to detect such evidence in the Solar System by telescopic, radar, infrared, direct probe, or other available means.

Freitas, R. A., Jr.

1983-11-01

38

Extraterrestrial fiberglass production using solar energy. [lunar plants or space manufacturing facilities  

NASA Technical Reports Server (NTRS)

A conceptual design is presented for fiberglass production systems in both lunar and space environments. The raw material, of lunar origin, will be plagioclase concentrate, high silica content slag, and calcium oxide. Glass will be melted by solar energy. The multifurnace in the lunar plant and the spinning cylinder in the space plant are unique design features. Furnace design appears to be the most critical element in optimizing system performance. A conservative estimate of the total power generated by solar concentrators is 1880 kW; the mass of both plants is 120 tons. The systems will reproduce about 90 times their total mass in fiberglass in 1 year. A new design concept would be necessary if glass rods were produced in space.

Ho, D.; Sobon, L. E.

1979-01-01

39

Spectral distribution of solar radiation  

NASA Technical Reports Server (NTRS)

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

Mecherikunnel, A. T.; Richmond, J.

1980-01-01

40

A global rain of micrometeorites following breakup of the L-chondrite parent body - Evidence from solar wind-implanted Ne in fossil extraterrestrial chromite grains from China  

NASA Astrophysics Data System (ADS)

Previous studies of limestone beds of mid-Ordovician age from both Sweden and China show that the Earth saw an at least two orders of magnitude increase in the influx of extraterrestrial material approximately 470 Ma, following the disruption of an L-chondrite parent body in the asteroid belt. Recovered extraterrestrial material consists of fossil meteorites and sediment-dispersed extraterrestrial chromite (SEC) grains, both with L-chondritic origin. Ne isotope analysis of SEC grains from one of the Swedish limestone sections revealed that the vast majority of the grains were delivered to Earth as micrometeorites. In this study, we extend the previous work, both in time and geographically, by measuring concentrations and isotopic ratios of Ne in individual SEC grains (60-120 ?m in diameter) from three different beds from a contemporary Middle Ordovician limestone section in China. All of the Chinese SEC grains, 44 in total, contain surface-implanted Ne of fractionated solar wind composition, implying that these grains were, as in the case of the Swedish SEC grains, delivered to Earth as micrometeorites. This gives further compelling evidence that the two to three orders of magnitude increase in the influx of micrometeoritic material following the breakup of the L-chondrite parent body was indeed a global event. The rain of micrometeorites prevailed for at least 2 Myr (the estimated time of the deposition of the topmost Chinese bed) after the breakup event.

Alwmark, C.; Schmitz, B.; Meier, M. M. M.; Baur, H.; Wieler, R.

2012-08-01

41

Operational solar irradiances for satellite drag applications  

Microsoft Academic Search

We report on major improvements to operational solar energy inputs for use in Jacchia-type empirical thermospheric density models to significantly improve Low Earth Orbit (LEO) satellite drag estimation. Three solar indices, compared to only one in the original Jacchia-type and MSIS-type models, best represent the complex interaction between a) the solar emission source (photosphere, chromosphere, corona), b) the irradiances' penetration

S. Bouwer; W. Tobiska

2006-01-01

42

Rotational Variability in Ultraviolet Solar Spectral Irradiance  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

43

CIRA Solar Irradiances and Solar\\/Geomagnetic Indices  

Microsoft Academic Search

Solar and geomagnetic inputs are required for use in empirical thermospheric density models. The constituent species in the thermosphere absorb spectrally resolved solar irradiances from soft X-ray (XUV) to Far Ultraviolet (FUV) wavelengths which deposit their energy at varying optical depths. In the high latitude regions, Joule heating and particle precipitation contribute secondary heating, which can be transported to lower

W. Kent Tobiska

2008-01-01

44

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

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

45

Measurement and analysis of diffuse solar irradiance  

SciTech Connect

Measurements of the diffuse irradiance on a horizontal surface using a continuous tracking occulting disc and a pyranometer have been examined for cloudless days. The part of the diffuse component that is blocked by the occulting disc (circumsolar component) is analyzed with respect to the aerosol optical depth at a wavelength of 500 nanometers, solar zenith angle, and precipitable water. The magnitude of the circumsolar component is determined from the direct normal irradiance measured with a pyrheliometer, aerosol optical depth and precipitable water measured with a Volz sun photometer, and direct normal irradiance calculated from a direct beam model. The pyrheliometer measures the direct beam as well as the circumsolar component. The model was used to estimate only the direct beam over the same spectral interval as measured by the pyrheliometer. The computed component is subtracted from the measured direct normal irradiance and multiplied by the cosine of the solar zenith angle. The difference is an approximate value of the circumsolar irradiance on a horizontal surface. It is found that the circumsolar irradiance is a maximum for small solar zenith angles, low aerosol optical depths, and small amounts of precipitable water. The largest change occurred for an increase in aerosol optical depth from .153 to .337, a solar zenith angle of 35/sup 0/, and 0.5 precipitable centimeters of water. The circumsolar component decreased by 17% and the measured diffuse increased by 50%.

Baker, C.B.

1983-01-01

46

Extraterrestrial hydrogeology  

Microsoft Academic Search

Subsurface water processes are common for planetary bodies in the solar system and are highly probable for exoplanets (planets outside the solar system). For many solar system objects, the subsurface water exists as ice. For Earth and Mars, subsurface saturated zones have occurred throughout their planetary histories. Earth is mostly clement with the recharge of most groundwater reservoirs from ample

Victor R. Baker; James M. Dohm; Alberto G. Fairén; Ty P. A. Ferré; Justin C. Ferris; Hideaki Miyamoto; Dirk Schulze-Makuch

2005-01-01

47

The search for extraterrestrial intelligence.  

PubMed

As far as we know, humanity is alone in the Universe: there is no definite evidence for the existence of extraterrestrial life, let alone extraterrestrial civilizations (ETCs) capable of communicating or travelling over interstellar distances. Yet popular speculation about the existence of ETCs abounds, including reports of alien visitations either now or in the past. But there is a middle way. It is now possible to put limits on the existence of ETCs of varying capabilities, within arbitrary distances from the Solar System, and conceive of real-world strategies whereby we might communicate with ETCs, or they with us. PMID:11234025

Wilson, T L

2001-02-22

48

The search for extraterrestrial intelligence  

NASA Astrophysics Data System (ADS)

As far as we know, humanity is alone in the Universe: there is no definite evidence for the existence of extraterrestrial life, let alone extraterrestrial civilizations (ETCs) capable of communicating or travelling over interstellar distances. Yet popular speculation about the existence of ETCs abounds, including reports of alien visitations either now or in the past. But there is a middle way. It is now possible to put limits on the existence of ETCs of varying capabilities, within arbitrary distances from the Solar System, and conceive of real-world strategies whereby we might communicate with ETCs, or they with us.

Wilson, T. L.

2001-02-01

49

Ionospheric Change and Solar EUV Irradiance  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

50

Electron irradiation of modern solar cells  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

51

Measurement and analysis of diffuse solar irradiance  

NASA Astrophysics Data System (ADS)

Measurements of the diffuse irradiance on a horizontal surface using a continuous tracking occulting disc and a pyranometer have been examined for cloudless days. The part of the diffuse component that is blocked by the occulting disc (circumsolar component) is analyzed with respect to the aerosol optical depth at a wavelength of 500 nanometers, solar zenith angle, and precipitable water. The magnitude of the circumsolar component is determined from the direct normal irradiance measured with a pyrheliometer, aerosol optical depth and precipitable water measured with a Volz sun photometer, and direct normal irradiance calculated from a direct beam model. The model was used to estimate only the direct beam over the same spectral interval as measured by the pyrheliometer. The computed component is subtracted from the measured direct normal irradiance and multiplied by the cosine of the solar zenith angle. The difference is an approximate value of the circumsolar irradiance on a horizontal surface. It is found that the circumsolar irradiance is a maximum for a small solar zenith angles, low aerosol optical depths, and small amounts of precipitable water.

Baker, C. B.

52

The effects of irradiation on the magnetic properties of rock and synthetic samples  

Microsoft Academic Search

Irradiations in space, by solar wind (SW), solar cosmic rays (SCR) (i.e., solar-flare-associated particles or solar energetic particles) and galactic cosmic rays (GCR) - the main source of space weathering of the solid Solar System bodies - may result in changes in magnetic properties of extraterrestrial materials, thus complicating the interpretation of the magnetism of meteorites, micrometeorites and lunar samples.

N. S. Bezaeva; P. Rochette; J. Gattacceca; J. Duprat; G. Rizza; P. Vernazza; V. I. Trukhin

2009-01-01

53

Measurement and Analysis of Diffuse Solar Irradiance.  

NASA Astrophysics Data System (ADS)

Measurements of the diffuse irradiance on a horizontal surface using a continuous tracking occulting disc and a pyranometer have been examined for cloudless days. The part of the diffuse component that is blocked by the occulting disc (circumsolar component) is analyzed with respect to the aerosol optical depth at a wavelength of 500 nanometers, solar zenith angle, and precipitable water. The magnitude of the circumsolar component is determined from the direct normal irradiance measured with a pyrheliometer, aerosol optical depth and precipitable water measured with a Volz sun photometer, and direct normal irradiance calculated from a direct-beam model (Bird, 1982). The pyrheliometer measures the direct beam as well as the circumsolar component. The model was used to estimate only the direct beam over the same spectral interval as measured by the pyrheliometer. The computed component is subtracted from the measured direct normal irradiance and multiplied by the cosine of the solar zenith angle. The difference is an approximate value of the circumsolar irradiance on a horizontal surface. It is found that the circumsolar irradiance is a maximum for a small solar zenith angles, low aerosol optical depths, and small amounts of precipitable water. The total diffuse component is a minimum for these conditions. The magnitude of the portion blocked is within 10% of the measured diffuse. In general, for a given solar zenith angle and low precipitable water, the correction to the measured diffuse decreases with an increase in aerosol optical depth; the diffuse component for these conditions increases while the circumsolar component decreases. The largest change occurred for an increase in aerosol optical depth from .153 to .337, a solar zenith angle of 35 degrees, and 0.5 precipitable centimeters of water. The circumsolar component decreased by 17% and the measured diffuse increased by 50%. This corresponded to a 33% reduction in the multiplying factor applied to the measured diffuse to obtain agreement with the measured diffuse plus the circumsolar component.

Baker, Clifford Bruce

54

Studies of Solar EUV Irradiance from SOHO  

NASA Technical Reports Server (NTRS)

The Extreme Ultraviolet (EUV) irradiance central and first order channel time series (COC and FOC) from the Solar EUV Monitor aboard the Solar and Heliospheric observatory (SOHO) issued in early 2002 covering the time period 1/1/96-31/1201 were analyzed in terms of other solar measurements and indices. A significant solar proton effect in the first order irradiance was found and characterized. When this effect is removed, the two irradiance time series are almost perfectly correlated. Earlier studies have shown good correlation between the FOC and the Hall core-to-wing ratio and likewise, it was the strongest component of the COC. Analysis of the FOC showed dependence on the F10.7 radio flux. Analysis of the CDC signals showed additional dependences on F10.7 and the GOES x-ray fluxes. The SEM FOC was also well correlated with thein 30.4 nm channel of the SOHO EUV Imaging Telescope (EIT). The irradiance derived from all four EIT channels (30.4 nm, 17.1 nm, 28.4 nm, and 19.5 nm) showed better correlation with MgII than F10.7.

Floyd, Linton

2002-01-01

55

ACRIM total solar irradiance monitoring during solar cycles 21 - 23  

NASA Astrophysics Data System (ADS)

A series of Active Cavity Radiometer Irradiance Monitoring experiments have provided state of the art Total Solar Irradiance (TSI) results during the 20 of past 22 years during solar activity cycles 21 - 23. A composite TSI record of more than 23 years has been constructed using results from the Nimbus7/ERB, SMM/ACRIM1, UARS/ACRIM2, SOHO/VIRGO and ACRIMSAT/ACRIM3 experiments. An upward trend in TSI between the successive solar cycle minima of 1986 and 1996 has been found in this r cord with a slope of 0.04 % per decade. If a trend ofe comparable magnitude were sustained on multi-decadal or century timescales, TSI variation could be an important component of climate change. Overlap and redundancy of TSI flight experiments have been e sential in the compilation of as precision TSI database. The strategy required to extend it depends crucially on the accuracy, precision and redundancy of future experiments.

Willson, R.; Mordvinov, A.

56

Solar Ultraviolet Irradiance Variability During the Decline of Cycle 23  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

57

Correlations Between Total Solar Irradiance and Spectral Irradiances Using SORCE Measurements  

Microsoft Academic Search

The SOlar Radiation and Climate Experiment (SORCE) was launched in January 2003 to measure both total solar irradiance (TSI) and spectral solar irradiance (SSI). The available spectral irradiances are contiguous from 115 nm to 1600 nm with nearly daily coverage, providing useful inputs to climate models since the Earth's atmospheric response is highly wavelength dependent. By correlating these relatively recent

G. Kopp

2006-01-01

58

Extraterrestrial Water  

Microsoft Academic Search

Life as we know it, i.e., carbon-based organisms that rely on RNA and DNA for information storage and transfer, requires liquid water. Thus, the search for life elsewhere in the universe generally begins with a search for liquid water. In our own Solar System, Earth is the only planet (or moon) that has liquid water at its surface. Mars and

J. F. Kasting

2002-01-01

59

Comparisons of modeled and measured spectral solar irradiance data  

SciTech Connect

This report contains comparisons of modeled and measured spectral solar irradiance data made at the Solar Energy research Institute (SERI). The modeled data were generated using a simple, spectral solar irradiance model developed at SERI; measured data were obtained with LI-COR model LI-1800 portable spectroradiometers specially modified at SERI. This work is part of a continuing endeavor to verify spectral irradiance models and to generate spectral irradiance data for different locations and climates.

Riordan, C.J.

1986-02-01

60

Solar Irradiance, Plage and SOHO UV Images  

NASA Astrophysics Data System (ADS)

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.

Lopresto, James C.; Manross, Kevin

1996-05-01

61

Fall 2010 Total Solar Irradiance Calibration Workshop  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

62

Solar spectral and total irradiance data from the SORCE mission  

Microsoft Academic Search

The SOlar Radiation and Climate Experiment (SORCE) satellite is scheduled to launch in December of 2002, to provide scientists with precise measurements of spectral and total solar irradiance data. T ese measurements are critical in theh understanding of solar activity and solar events, and the influence of solar variability on the upper atmospheric chemistry, dynamics, and climate change. SORCE will

S. Ahmad; J. Johnson; G. Serafino

2002-01-01

63

Long-term variations in total solar and UV irradiances  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

64

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

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) has developed the LASP Interactive Solar IRradiance Datacenter (LISIRD, http://lasp.colorado.edu/lisird/) web site to provide access to a comprehensive set of solar irradiance measurements and related datasets. Current data holdings include products from NASA missions SORCE, UARS, SME, and TIMED-SEE. 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 Total Solar Irradiance (TSI). Other datasets include solar indices, spectral and flare models, solar images, and more. The LISIRD web site features updated plotting, browsing, and download capabilities enabled by dygraphs, JavaScript, and Ajax calls to the LASP Time Series Server (LaTiS). In addition to the web browser interface, most of the LISIRD datasets can be accessed via the LaTiS web service interface that supports the OPeNDAP standard. OPeNDAP clients and other programming APIs are available for making requests that subset, aggregate, or filter data on the server before it is transported to the user. This poster provides an overview of the LISIRD system, summarizes the datasets currently available, and provides details on how to access solar irradiance data products through LISIRD's interfaces.

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

2011-12-01

65

Possible dependence between the total solar irradiance and di- methylsulphide  

Microsoft Academic Search

Solar variability is one of the main natural influences on the Earth's climate. Biological processes are pro - foundly affected by the solar irradiance. Some of these processes have been proposed to change the cloud albedo and therefore impact the climate. Here we investigate the relation between the total solar irradiance (TSI) and the global concentration of Dimethylsulphide (DMS), produced

B. Mendoza; E. L. Flores-Márquez; A. Ramírez-Rojas; A. Martínez-Arroyo

2009-01-01

66

Solar irradiance estimation from geostationary satellite data: 1. Statistical models  

Microsoft Academic Search

The use of satellite data to estimate solar irradiance at ground level represents a valid alternative to ground measurements of solar radiation. The best known methods of estimating the solar irradiance at the earth's surface using geostationary satellite data are reviewed. The models may be classified into statistical and physical models, depending on the approach used to treat the interaction

M. Noia; C. F. Ratto; R. Festa

1993-01-01

67

Tools For Understanding And Forecasting Solar Spectral Irradiance Variations  

Microsoft Academic Search

We describe the application and current status of the Solar Radiation Physical Modeling (SRPM) project for understanding the nature of the solar spectral irradiance (SSI) variations from EUV to IR wavelengths. These tools enable up to a few weeks forecast of variations of the spectrum of the solar irradiance at any location in the Heliosphere. These methods are been also

Juan Fontenla; M. Haberreiter; J. Harder

2009-01-01

68

Life on Other Worlds: The 20th- Century Extraterrestrial Life Debate  

NASA Astrophysics Data System (ADS)

List of illustrations; List of tables; Acknowledgements; Introduction; 1. From the physical world to the biological universe: Democritus to Lowell; 2. Life in the solar system; 3. Solar systems beyond; 4. Extraterrestrials in literature and the arts: the role of imagination; 5. The UFO controversy and the extraterrestrial hypothesis; 6. The origin and evolution of life in the extraterrestrial context; 7. SETI: the search for extraterrestrial intelligence; 8. The meaning of life; 9. Summary and conclusion: the biological universe; Select bibliographical essay; Index.

Dick, Steven J.

2001-06-01

69

Zone plate EUV solar irradiance monitor  

NASA Astrophysics Data System (ADS)

Measuring the solar extreme ultraviolet (EUV) irradiance is a high priority for space weather and upper atmospheric research. We have designed and fabricated a sensor to measure the total solar irradiance in the extremely variable 17.1- 19.5 nm spectral band that contains numerous Fe emission lines and we are developing another similar sensor for the 30.4 nm He II spectral line. Each of these sensors uses a 4 mm diameter zone plate (ZP) to focus the in-band solar radiation onto a small pinhole in front of a detector. The focal length of a ZP is inversely proportional to wavelength, and the pinhole's diameter is sufficient to admit the in-band radiation from the full solar disk and inner corona. A 2 mm diameter central occulting disk minimizes the undiffracted (0-order) and out-of-band radiation that reaches the pinhole. Two thin Al film filters, one in front of the ZP and one deposited on the detector, are virtually opaque to wavelengths longer than EUV and prevent the detector from responding to most of the solar spectrum. A ZP has a number of advantages over a diffraction grating. Because it focuses in-band radiation, a ZP allows the detector to be smaller than the aperture, reducing both the dark current and the out-of-band response. The circular symmetry of the ZP eliminates both the polarization sensitivity and the shift in the spectral band with field angle that are intrinsic to a linear grating. The optical assembly is contained in a very small volume. We are planning to fly the Fe-band sensor as a secondary payload on NRL's VERIS sounding rocket solar measurement mission in the near future and are investigating the feasibility of flying both sensors on a future CubeSat mission.

Bremer, James C.; Seely, John F.; Holland, Glenn E.; Feng, Yan

2009-08-01

70

CIRA Solar Irradiances and Solar/Geomagnetic Indices  

NASA Astrophysics Data System (ADS)

Solar and geomagnetic inputs are required for use in empirical thermospheric density models. The constituent species in the thermosphere absorb spectrally resolved solar irradiances from soft X-ray (XUV) to Far Ultraviolet (FUV) wavelengths which deposit their energy at varying optical depths. In the high latitude regions, Joule heating and particle precipitation contribute secondary heating, which can be transported to lower latitudes by meridional winds. However, empirical models generally do not use the sophistication of spectrally resolved solar irradiances or Joule heating and particle precipitation. Instead, simplification of an energy input is accomplished in the form solar and geomagnetic surrogates, i.e., proxies and indices. A proxy is a substitute for a distinctly different energy input while an index expresses the activity level of an energy input. Recently, in addition to the traditional 10.7-cm flux (F10.7) that is a proxy for solar Extreme Ultraviolet (EUV) irradiances, a new solar irradiance index (S10.7) and a new proxy (M10.7) have been developed for use in empirical thermospheric density models. These three solar indices and proxies best represent the complex interaction between the solar emission source (photosphere, chromosphere, corona) with the irradiances' penetration into the thermosphere (unit optical depth in the middle and lower thermosphere) and the length of time for energy transfer between thermospheric layers (thermal process of molecular conduction or kinetic process of molecular diffusion). The S10.7 index (previously called SEUV) accounts for the majority of the daily density variability with a 1-day lag, is reported in units of F10.7, is the chromospheric EUV energy between 26-34 nm as measured by the SOHO SEM instrument, and is deposited above 200 km. The M10.7 proxy accounts for the next significant factor of the daily density variability with a 5-day lag and is the Mg II core-to-wing ratio reported in units of F10.7. It is used as a substitute for the FUV Schumann-Runge Continuum (SRC) energy dominated by the 145-165 nm range that has a unit optical depth in the lower thermosphere and is the main source of thermospheric molecular oxygen dissociation that is not historically included in Jacchiaand MSIS-type models. The F10.7 proxy accounts for a minority of the daily density variability with a 1-day lag and represents the transition region/coronal XUV/EUV energy less than 121 nm with a unit optical depth throughout the thermosphere. We describe the use of these three solar irradiance indices and proxies in research and operational empirical thermospheric density models. We also describe the use of Ap and Dst geomagnetic indices as applied to thermospheric density modeling.

Tobiska, W. Kent

71

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

72

Bolometric imager for solar irradiance studies  

NASA Astrophysics Data System (ADS)

We are presently developing a solar imager with spectrally uniform photometric response over all wavelengths between the UV and IR. Such a Solar Bolometric Imager (SBI) will be capable of accurately measuring heat flow inhomogeneities at the sun's photosphere and will provide an innovative new tool for identifying mechanisms of long-term solar luminosity variation. Our work builds on recent advances in uncooled, relatively high-definition thermal arrays. We have shown that the spectral absorptance of these arrays can be modified by deposition of gold blacks, to provide spectrally uniform response over at least the wavelength range between about 0.3(mu) and 2.5(mu) containing over 95 percent of the total solar irradiance. Our ongoing work is intended to show that quantitative photometry of the solar disc can be performed with such a modified array. We are constructing a breadboard SBI for immediate use with an 8-bit ferro- electric camera, developing a 12-bit camera to make full use of the ferro-electric array's capabilities, and optimizing our process of gold-blacking the TI arrays. Much of the science potential of the SBI could be realized in a balloon experiment. The combination of the SBI and a cavity radiometer would also constitute an excellent SMEX experiment to address a key challenge identified in the Sun- Earth Connection Roadmap recently issued by NASA/OSS.

Foukal, Peter V.

1998-11-01

73

Reconstructing the Solar VUV Irradiance Over the Past 60 Years  

NASA Technical Reports Server (NTRS)

Actual observations of the solar spectral irradiance are extremely limited on climate time scales; therefore, various empirical models use solar proxies to reconstruct the actual output of the Sun over long time scales. The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a I-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric. A brief overview of the proxies used in the FISM model will be given, and also discussed is how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM estimates and its accuracies. Also presented will be a discussion of other solar irradiance proxies and measurements, and their associated uncertainties, used for solar spectral reconstructions.

Chamberlin, Phillip C.

2011-01-01

74

The variability of the solar ultraviolet spectral irradiances  

NASA Technical Reports Server (NTRS)

Available data on the solar spectral irradiances at wavelengths below 3100 A are extremely limited and there are major uncertainties in many of the measurements. In particular, there is major disagreement on the magnitude of the variability of the spectral irradiances over the solar cycle. The effects of different solar features on the ultraviolet spectral irradiances over both the 28 day solar rotation period and over the solar cycle are discussed. It is proposed that any attempt to predict the magnitudes of the ultraviolet spectral irradiances must take into account a long term variability of emission from quiet regions of the solar disk over the solar cycle. The need for direct long term monitoring of the ultraviolet spectral irradiances is emphasized.

Timothy, J. G.

1979-01-01

75

Solar Irradiance Variations on Active Region Time Scales  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

76

Variations in solar Lyman alpha irradiance on short time scales  

Microsoft Academic Search

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

J. M. Pap

1992-01-01

77

Multivariate Analysis of Solar Spectral Irradiance Measurements  

NASA Technical Reports Server (NTRS)

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.

Pilewskie, P.; Rabbette, M.

2001-01-01

78

Intermittency and variability of daily solar irradiation  

NASA Astrophysics Data System (ADS)

This paper deals the study of variability and intermittency of solar irradiation using an analogy with the turbulence and thus making use of some methodologies used in the study of intermittency of the turbulence. An analysis of the shape of the PDFs corresponding to the increments in the clearness and transmittance indexes, for direct and global radiations, is presented. In addition a study of the relations between the scaling exponents of the structure functions of the clearness and transmittance indexes and the orders of these structure functions has been carried out. According to the study, the range of relative variability is due to changes in the atmospheric components that play a role in the attenuation of solar irradiation. This range of variability is higher in the case of the global irradiation than in the case of the direct. Moreover, the multifractality is showed more intense in sites where, due to local effects, sharper variations in the radiation can be expected, as the case of deserts.

Vindel, J. M.; Polo, J.

2014-06-01

79

Solar Spectral Irradiance Changes during Cycle 24  

NASA Astrophysics Data System (ADS)

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 ? >~ 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.

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

2014-07-01

80

AEM of Extraterrestrial Materials.  

National Technical Information Service (NTIS)

Modifications to and maintenance of the JEOL 100 CX electron microscope are discussed. Research activity involving extraterrestrial matter, cosmic dust, stratosphere dust, and meteorites is summarized.

I. D. R. Mackinnon

1982-01-01

81

AEM of extraterrestrial materials  

NASA Technical Reports Server (NTRS)

Modifications to and maintenance of the JEOL 100 CX electron microscope are discussed. Research activity involving extraterrestrial matter, cosmic dust, stratosphere dust, and meteorites is summarized.

Mackinnon, I. D. R.

1982-01-01

82

Accessing Solar Irradiance Data Products From the LASP Interactive Solar IRradiance Datacenter (LISIRD)  

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) is enhancing the LASP Interactive Solar IRradiance Datacenter (LISIRD) to provide access to a comprehensive set of solar spectral irradiance measurements. LISIRD has recently been updated to serve many new datasets and models, including sunspot index, photometric sunspot index, Lyman-alpha, and magnesium-II core-to-wing ratio. A new 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 almost continuous coverage from 1981 to the present, while Hydrogen Lyman-alpha (121.6 nm) measurements / models date from 1947 to the present. 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 interfaces at http://lasp.colorado.edu/lisird/.

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

2009-12-01

83

Christ and extraterrestrial life  

Microsoft Academic Search

This paper explores the relationship between Incarnation and extraterrestrial life in view of the question: can extraterrestrials be saved? The Franciscan theology of Bonaventure and Scotus is used to explore “exoChristology” by examining the Incarnation as a theological rather than anthropological event. The primacy of Christ, held by Franciscan theologians, provides an integral relationship between Christ and creation. From this

Ilia Delio O. S. F

2007-01-01

84

LISIRD: LASP Interactive Solar Irradiance Data Center  

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder has been involved in numerous space-borne missions to directly measure and understand the variability of the Sun's energy output and its impact on global climate change. The LASP Interactive Solar Irradiance Data Center (LISIRD) provides a web site with interactive graphics to explore, subset, and download these and other solar related datasets. The LISIRD collections include observations of total and spectral irradiance with coverage from the X-ray to the infrared from projects such as SME, UARS SOLSTICE, SNOE, TIMED SEE, SORCE, and SDO EVE plus a growing number of related data products, proxies, and models. The LISIRD data services are backed by the LaTiS data server which presents a unified RESTful web service interface to slice, dice, and perform select server-side operations as the data are dynamically streamed to files of your desired format or directly into your code or analysis tools. Come see the data products and services that LISIRD has available and help us to improve them to better meet your needs.

Lindholm, D. M.; Wilson, A.

2013-12-01

85

Reconstruction of solar irradiance since 1610: Implications for climate change  

Microsoft Academic Search

Solar total and ultraviolet (UV) irradiances are reconstructed annually from 1610 to the present. This epoch includes the Maunder Minimum of anomalously low solar activity (circa 1645-1715) and the subsequent increase to the high levels of the present Modern Maximum. In this reconstruction, the Schwabe (11-year) irradiance cycle and a longer term variability component are determined separately, based on contemporary

Judith Lean; Juerg Beer; Raymond Bradley

1995-01-01

86

Solar extreme ultraviolet irradiance: Present, past, and future  

Microsoft Academic Search

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

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

2011-01-01

87

Research Spotlight: More accurate measurements of total solar irradiance  

NASA Astrophysics Data System (ADS)

Radiation from the Sun is the dominant source of energy input to the Earth's climate system; even small variations in solar irradiance can produce noticeable climate changes on global and regional scales. Determining how much of the observed global change can be attributed to variations in the Sun's output and how much can be attributed to human or other influences requires an accurate record of solar irradiance. Measurements of solar irradiance made by the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) satellite give a value of total solar irradiance that is significantly lower than previously accepted values. Kopp and Lean show that this new, lower value is more accurate than measurements made using older instruments. They used laboratory studies and satellite calibrations to diagnose and quantify error sources on TIM and other space-based solar radiometers and found that earlier radiometers measured higher values of solar irradiance because they included scattered instrument light in their signals, while the different optical design of the TIM radiometer reduces this spurious signal and acquires more accurate measurements. They also show that TIM's high stability gives improved agreement with models estimating solar variability, concluding that this new instrument provides the most accurate value of solar irradiance and helps improve estimates of the Sun's influence on climate. (Geophysical Research Letters, doi:10.1029/2010GL045777, 2011)

Tretkoff, Ernie

2011-02-01

88

GOME and SCIAMACHY solar measurements: Solar spectral irradiance and Mg II solar activity proxy indicator .  

NASA Astrophysics Data System (ADS)

GOME (Global Ozone Monitoring Experiment, 1995-present) and SCIAMACHY (SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY, 2002-present) provide solar observations in the visible and near UV since 1995. SCIAMACHY also measures in the near IR with some gaps up to 2380 nm. The solar spectral irradiance measured by SCIAMACHY is compared with results from other data sources such as SIM, SOLSPEC, SOLSTICE, and SUSIM and is generally in good agreement within 2 to 3% in most cases. The Mg II index is derived from daily solar observations in the near UV spectral region which provides a good measure of the solar EUV variability. For the understanding of the solar-terrestrial climate interaction the establishment of a long Mg II time series spanning several decades is important. A continuous solar Mg II index from 1995 to 2005 composed from GOME and SCIAMACHY solar measurements is presented and compared with Mg II data available from NOAA.

Skupin, J.; Weber, M.; Noël, S.; Bovensmann, H.; Burrows, J. P.

89

Operational solar irradiances for satellite drag applications  

NASA Astrophysics Data System (ADS)

We report on major improvements to operational solar energy inputs for use in Jacchia-type empirical thermospheric density models to significantly improve Low Earth Orbit (LEO) satellite drag estimation. Three solar indices, compared to only one in the original Jacchia-type and MSIS-type models, best represent the complex interaction between a) the solar emission source (photosphere, chromosphere, corona), b) the irradiances' penetration into the thermosphere (unit optical depth in the middle and lower thermosphere), and c) the length of time for energy transfer between thermospheric layers, i.e., the thermal process of molecular conduction or the kinetic process of molecular diffusion. We have found that the existing 10.7-cm radio flux (F10.7) solar proxy plus two new solar indices/proxies substantially improve density modeling. First, the new S10.7 index accounts for 75 percent of the daily density variability with a 1-day lag, is reported in units of F10.7, is the chromospheric EUV energy between 26-34 nm as measured by the SOHO SEM instrument, and is absorbed by atomic oxygen above 200 km. Second, the new M10.7 proxy accounts for 12 percent of the daily density variability with a 5-day lag. It is formed by the Mg II core-to-wing ratio reported in units of F10.7, is used as a substitute for the far ultraviolet (FUV) lower chromosphere/photosphere Schumann-Runge Continuum (SRC) energy that is dominated by the 145-165 nm range and has a unit optical depth in the lower thermosphere, and is the main source of thermospheric molecular oxygen dissociation not historically included in Jacchia- and MSIS-type models. Third, the F10.7 proxy accounts for 13 percent of the daily density variability with a 1-day lag, is the transition region/coronal XUV/EUV energy less than 121 nm and has a unit optical depth throughout the thermosphere, being absorbed by many neutral species. We describe the deployment of the new solar indices in an operational system for use by the space systems community that is concerned with LEO satellite drag.

Bouwer, S.; Tobiska, W.

2006-12-01

90

A reference solar spectral irradiance for use in atmospheric modeling  

NASA Technical Reports Server (NTRS)

The present state of knowledge concerning the absolute magnitude and temporal variability of the solar spectral irradiance is outlined with emphasis on wavelengths relevant to the mesosphere and stratosphere. Reference spectra for the wavelength region 175 to 850 nm are presented including estimates for solar maximum and solar minimum conditions. Values for the Lyman alpha emission are given separately.

1982-01-01

91

Genesis capturing the sun: Solar wind irradiation at Lagrange 1  

Microsoft Academic Search

Genesis, a member of NASAs Discovery Mission program, is the world's first sample return mission since the Apollo program to bring home solar matter in ultra-pure materials. Outside the protection of Earth's magnetosphere at the Earth-Sun Lagrange 1 point, the deployed sample collectors were directly exposed to solar wind irradiation. The natural process of solar wind ion implantation into a

Michael J. Calaway; Eileen K. Stansbery; Lindsay P. Keller

2009-01-01

92

7. The Search for Extraterrestrial Life  

Microsoft Academic Search

Looking at the nature, origin, and evolution of life on Earth is one way of assessing whether extraterrestrial life exists on Earth-like planets elsewhere (see Chaps. 5 and 6). A more direct approach is to search for favorable conditions and traces of life on other celestial bodies, both in the solar system and beyond. Clearly, there is little chance of

Ulmschneider Peter

2003-01-01

93

A Prediction Model Of Solar Euv Irradiance On The Basis Of Solar Magnetic Flux Evolution  

Microsoft Academic Search

Harvey (1991, 1994) determined the correlation between total solar surface magnetic flux and solar irradiance (i.e. F10.7, 1-8 Å and Lyman alpha). This implies that if one could predict the solar magnetic flux as it changes over time, then Harvey's correlation could be used to also predict solar EUV irradiance. Wu et al. (1993) have developed a magnetohydrodynamic (MHD) photospheric

S. T. Wu; A. H. Wang; C. D. Fry; W. K. Tobiska; J. Pap

2004-01-01

94

Guide to solar reference spectra and irradiance models  

NASA Astrophysics Data System (ADS)

The international standard for determining solar irradiances was published by the International Standards Organization (ISO) in May 2007. The document, ISO 21348 Space Environment (natural and artificial) - Process for determining solar irradiances, describes the process for representing solar irradiances. We report on the next progression of standards work, i.e., the development of a guide that identifies solar reference spectra and irradiance models for use in engineering design or scientific research. This document will be produced as an AIAA Guideline and ISO Technical Report. It will describe the content of the reference spectra and models, uncertainties and limitations, technical basis, data bases from which the reference spectra and models are formed, publication references, and sources of computer code for reference spectra and solar irradiance models, including those which provide spectrally-resolved lines as well as solar indices and proxies and which are generally recognized in the solar sciences. The document is intended to assist aircraft and space vehicle designers and developers, heliophysicists, geophysicists, aeronomers, meteorologists, and climatologists in understanding available models, comparing sources of data, and interpreting engineering and scientific results based on different solar reference spectra and irradiance models.

Tobiska, W. Kent

95

The Search for Extraterrestrial Artifacts (SETA)  

NASA Astrophysics Data System (ADS)

The rationale for the use of interstellar artifacts by intelligent life in the universe is described. The advantages of using interstellar probes as a means of exploration and communication are presented and shown to be significant enough to counter the time, energy, and technology arguments generally raised against contact via extraterrestrial artifacts. Four classes of artifacts are defined: Those seeking contact, those seeking to avoid contact, those intended to provide a passive technological threshold for detection, and those for which detection is irrelevant. The Search for Extraterrestrial Artifacts (SETA) is based on the latter two classes. Under the assumption that an extraterrestrial probe will be interested in life in the solar system, a near-earth search space is defined. This search space is accessible now with ground and satellite observing facilities. The current observational status of SETA is reviewed and contrasted with the achievable detection limits for the different parts of the search space.

Freitas, R. A., Jr.; Valdes, F.

1984-10-01

96

Absolute, Extreme-Ultraviolet Solar Spectral Irradiance Monitor (AESSIM).  

National Technical Information Service (NTIS)

The goal of this research program was development of a method for obtaining daily radiometrically accurately, solar spectral irradiance data at EUV wavelengths. In orbit radiometric instrumentation recalibration is a fundamental requirement for accurate s...

W. H. Parkinson P. L. Smith

1994-01-01

97

Absolute, Extreme Ultraviolet Solar Spectral Irradiance Monitor (AESSIM).  

National Technical Information Service (NTIS)

The goal of this research program is development of a method for obtaining daily, radiometrically accurate, solar spectral irradiance data at extreme-ultraviolet (EUV) wavelengths. In-orbit radiometric instrumentation recalibration is a fundamental requir...

W. H. Parkinson

1992-01-01

98

Absolute, Extreme Ultraviolet Solar Spectral Irradiance Monitor (AESSIM).  

National Technical Information Service (NTIS)

The goal of this research program is development of a method for obtaining daily, radiometrically accurate, solar spectral irradiance data at extreme-ultraviolet (EUV) wavelengths. In-orbit radiometric instrumentation recalibration is a fundamental requir...

W. H. Parkinson

1991-01-01

99

The Signature of Solar Activity in the Infrared Spectral Irradiance  

Microsoft Academic Search

The effects of solar activity on the spectral irradiance have been studied using atmospheric semiempirical models developed from observations of the various surface features observed on the Sun. From these models, it has been the long-standing belief that the contributions of active regions to solar irradiance at wavelengths in the range of 1.2-3 mum is negative; that is, their net

J. M. Fontenla; J. Harder; G. Rottman; T. N. Woods; G. M. Lawrence; S. Davis

2004-01-01

100

The satellite total solar irradiance database  

NASA Astrophysics Data System (ADS)

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 provide better than 5 ppm/yr (0.0005%/yr) traceability. The most scientifically useful application of the series of satellite TSI experiments since 1978 is the compilation of a precise, long-term composite TSI database for comparative studies of climate change and solar physics. Comparisons of overlapping observations are used to provide a contiguous database that transfers traceability at the level of TSI observational precision. Several TSI composites have been constructed from the satellite database. The ACRIM composite is unique in that it uses results published by the satellite experiment science teams to produce a TSI time series with an unbiased relationship to their original calibrations. Others modify the data sets to conform the results to TSI proxy models.

Willson, R. C.

2009-12-01

101

Variations in solar Lyman alpha irradiance on short time scales  

NASA Technical Reports Server (NTRS)

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.

Pap, J. M.

1992-01-01

102

Solar spectral irradiance and atmospheric transmission at Mauna Loa Observatory  

Microsoft Academic Search

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

Glenn E. Shaw

1982-01-01

103

Lower Solar Extreme Ultraviolet Irradiances During the Solar Cycle 23/24 Minimum (Invited)  

NASA Astrophysics Data System (ADS)

The solar cycle 23/24 minimum in 2007-2010 is deeper and broader than recent cycle minima, and this minimum appears similar to the minima in the early 1900s. With the best-ever solar irradiance measurements from SOHO, SORCE, and TIMED, this minimum offers a unique opportunity to advance our understanding of secular (long-term) changes in the solar irradiance. A first task towards this goal is the comparison of the 2007-2009 irradiance results of this current minimum to the irradiance levels during the previous minimum in 1996. The solar extreme ultraviolet (EUV: 10-120 nm) irradiance is lower in 2008 than in 1996 by about 15%. There are uncertainties in these irradiance results because they depend strongly on understanding instrument degradation trends over 12 years. Nonetheless, the reduced solar EUV irradiance in 2008 are consistent with the reduced solar magnetic field and increase in low-latitude coronal holes during this recent cycle minimum. Furthermore, Earth’s thermosphere is cooler and less dense during this period in response to there being lower solar EUV irradiance.

Woods, T. N.

2010-12-01

104

Photo-Recovery of Electron-Irradiated GAAS Solar Cells.  

National Technical Information Service (NTIS)

The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, in...

A. Meulenberg

1995-01-01

105

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

106

Genesis capturing the sun: Solar wind irradiation at Lagrange 1  

Microsoft Academic Search

Genesis, a member of NASAs Discovery Mission program, is the world’s first sample return mission since the Apollo program to bring home solar matter in ultra-pure materials. Outside the protection of Earth’s magnetosphere at the Earth–Sun Lagrange 1 point, the deployed sample collectors were directly exposed to solar wind irradiation. The natural process of solar wind ion implantation into a

Michael J. Calaway; Eileen K. Stansbery; Lindsay P. Keller

2009-01-01

107

Solar spectral and total irradiance data from the SORCE mission  

NASA Astrophysics Data System (ADS)

The SOlar Radiation and Climate Experiment (SORCE) satellite is scheduled to launch in December of 2002, to provide scientists with precise measurements of spectral and total solar irradiance data. These measurements are critical in the understanding of solar activity and solar events, and the influence of solar variability on the upper atmospheric chemistry, dynamics, and climate change. SORCE will carry four instruments including Total Irradiance Monitor (TIM), Solar Stellar Irradiance Comparison Experiment (SOLSTICE), Spectral Irradiance Monitor (SIM), and the Extreme Ultraviolet Photometer System (XPS). These instruments using enhanced technology will provide more accurate spectral and total solar irradiance measurements compared to the precursor sensors. Scientists realized very early that long-term precise measurements of total solar irradiance are necessary to fully understand the effect of solar variability on the climate. The TIM instrument on SORCE will provide a measurement of Total Solar Irradiance (TIS) with an absolute accuracy of 0.01%. It will continue the long-term data record of TIS measurements which started with the Earth Radiation Budget instrument on Nimbus-7 in 1979, followed by a series of Active Cavity Radiometer Irradiance Monitor (ACRIM) instruments. ACRIM I flew on the Solar Maximum Mission in 1980, ACRIM II on the Upper Air Research Satellite (UARS) in 1991, and recently (December 20, 1999) the ACRIM III flew on the ACRIMSAT. Precise knowledge of fluctuations of Solar Ultra-Violet (UV) radiation is much needed since this radiation is highly variable and strongly influences upper atmospheric chemistry and dynamics. SOLSTICE will measure spectral irradiance from 115 nm to 300 nm with a resolution of 1 nm, and an absolute accuracy of better than 5%. SOLSTICE nighttime UV measurements from selected bright blue stars provide a calibration source enabling the direct comparison of solar irradiance measurements made during the SORCE mission with previous and future observations. Radiation at the longer visible and infrared wavelengths penetrates into the lower atmosphere and plays a dominant role in the global energy balance, and is an essential determinant of atmospheric stability and convection. The SIM instrument will provide precise near UV, visible, and near infrared spectral irradiance between 200 nm and 2000 nm with a resolution varying from 1 nm to 34 nm and an absolute accuracy of 0.03%. The XPS instrument will take readings in the far or extreme ultraviolet, with wavelengths much shorter than those measured by SOLSTICE, and down into the soft or low-energy X-ray region. It will provide six broadband samples of the XUV from 1 31 nm and at Lyman- (121.6 nm) with an absolute accuracy of 12%.- Scientists will use XPS data to study the Sun's corona and transition zone. All standard products from SORCE will be archived at the Goddard Earth Sciences DAAC, thus extending the ten year long data records of solar data from the UARS mission, e.g. UV spectral data from the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and SOLSTICE onboard UARS. The continuity of solar measurements will be provided with the launch of the Aura spacecraft in early 2004 (the third mission in NASA's Earth Observing System program), in conjunction with the second Solar Radiation and Climate Experiment (SORCE) satellite slated for launch in late 2005. This presentation will provide an overview of the SORCE data products, which will be freely available from the GES DAAC. The presentation will also provide details of the data support and services provided by the DAAC Upper Atmosphere Data Support Team, in support of the users of the satellite data products.

Ahmad, S.; Johnson, J.; Serafino, G.

108

Solar spectral and total irradiance data from the SORCE mission  

NASA Astrophysics Data System (ADS)

The SOlar Radiation and Climate Experiment (SORCE) satellite is scheduled to launch in December of 2002, to provide scientists with precise measurements of spectral and total solar irradiance data. T ese measurements are critical in theh understanding of solar activity and solar events, and the influence of solar variability on the upper atmospheric chemistry, dynamics, and climate change. SORCE will carry four instruments including Total Irradiance Monitor (TIM), Solar Stellar Irradiance Comparison Experiment (SOLSTICE), Spectral Irradiance Monitor (SIM), and the Extreme Ultraviolet Photometer System (XPS). These instruments using enhanced technology will provide more accurate spectral and total solar irradiance measurements compared to the precursor sensors. Scientists realized very early that long-term precise measurements of total solar irradiance are necessary to fully understand the effect of solar variability on the climate. The TIM instrument on SORCE will provide a measurement of Total Solar Irradiance (TIS) with an absolute accuracy of 0.01%. It will continue the long-term data record of TIS measurements which started with the Earth Radiation Budget instrument on Nimbus-7 in 1979, followed by a series of Active Cavity Radiometer Irradiance Monitor (ACRIM) instruments. ACRIM I flew on the Solar Maximum Mission in 1980, ACRIM II on the Upper Air Research Satellite (UARS) in 1991, and recently (December 20, 1999) the ACRIM III flew on the ACRIMSAT. Precise knowledge of fluctuations of Solar Ultra-Violet (UV) radiation is much needed since this radiation is highly variable and strongly influences upper atmospheric chemistry and dynamics. SOLSTICE will measure spectral irradiance from 115 nm to 300 nm with a resolution of 1 nm, and an absolute accuracy of better than 5%. SOLSTICE nighttime UV measurements from selected bright blue stars provide a calibration source enabling the direct comparison of solar irradiance measurements made during the SORCE mission with previous and future observations. Radiation at the longer visible and infrared wavelengths penetrates into the lower atmosphere and plays a dominant role in the global energy balance, and is an essential determinant of atmospheric stability and convection. The SIM instrument will provide precise near UV, visible, and near infrared spectral irradiance between 200 nm and 2000 nm with a resolution varying from 1 nm to 34 nm and an absolute accuracy of 0.03%. The XPS instrument will take readings in the far or extreme ultraviolet, with wavelengths much shorter than those measured by SOLSTICE, and down into the soft or low-energy X-ray region. It will provide six broadband samples of the XUV from 1-31 nm and at Lyman- (121.6 nm) with an absolute accuracy of 12%. Scientists will use XPS data to study the Sun's corona and transition zone. All standard products from SORCE will be archived at the Goddard Earth Sciences DAAC, thus extending the ten year long data records of solar data from the UARS mission, e.g. UV spectral data from the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and SOLSTICE onboard UARS. The continuity of solar measurements will be provided with the launch of the Aura spacecraft in early 2004 (the third mission in NASA's Earth Observing System program), in conjunction with the second Solar Radiation and Climate Experiment (SORCE) satellite slated for launch in late 2005. This presentat ion will provide an overview of the SORCE data products, which will be freely available from the GES DAAC. The presentation will also provide details of the data support and services provided by the DAAC Upper Atmosphere Data Support Team, in support of the users of the satellite data products.

Ahmad, S.; Johnson, J.; Serafino, G.

109

Comparison of Solar UV Spectral Irradiance from SUSIM and SORCE  

NASA Astrophysics Data System (ADS)

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 uc(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 uc(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 results can be used for climate-modeling studies.

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

2014-04-01

110

Ground-Based Correlates of Solar Irradiance Variation  

NASA Technical Reports Server (NTRS)

Ground-based instruments cannot directly measure solar irradiance variability at the 0.1% level at which it occurs because of the earth's atmosphere. However, many forms of ground-based solar observations correlate well with solar irradiance variations, and this fact has been used to construct facular-sunspot models which can explain about 90% of the variance of total solar irradiance as observed by spacecraft radiometers. It is not yet clear whether remaining discrepancies are observational or require additional sources in the model. This paper is a selective review of the current status of the use of ground-based data to understand spacecraft observations of solar irradiance and to apply this understanding to periods before space-based measurements were available. New results from the extension of the histogram analysis of NASA/NSO spectromagnetograph observations (Jones et al., 2000, ApJ529, 1070) to the period from Nov. 1992 to Sep. 2000 are reported which confirm that strong mixed polarity magnetic regions (quiet network) are not significantly correlated with total solar irradiance and which show an unexplained linear trend in the residuals of a multiple regression.

Jones, Harrison P.

2001-01-01

111

A combined irradiance-transmittance solar spectrum and its application to photovoltaic efficiency calculations.  

PubMed

SOLTRAN is a flexible computer model for the direct solar beam intensity spectrum at the earth's surface. It has been derived by combining the extra-terrestrial solar spectrum with the atmospheric transmittance spectrum. Application of SOLTRAN to the calculation of the potential efficiency of photovoltaic cells demonstrates the effect of atmospheric absorption bands. These bands prevent unequivocal assignment of optimum energy gap values. PMID:17839483

Ireland, P J; Wagner, S; Kazmerski, L L; Hulstrom, R L

1979-05-11

112

An assessment of the solar irradiance record for climate studies  

NASA Astrophysics Data System (ADS)

Total solar irradiance, the spatially and spectrally integrated radiant output from the Sun at a mean Sun-Earth distance of 1 astronomical unit, provides nearly all the energy driving the Earth's climate system. Variations in this energy, particularly over long time scales, contribute to changes in Earth's climate and have been linked to historical glaciation and inter-glacial periods as well as having a small effect on more recent global warming. Accurate measurements of solar irradiances require measurements above the Earth's atmosphere. The total solar irradiance spaceborne record began in 1978 and has been uninterrupted since, with over a dozen instruments contributing to the present solar climate data record. I assess the required and achieved accuracies of this record with a focus on its value for climate studies.

Kopp, Greg

2014-04-01

113

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

Microsoft Academic Search

The SOHO\\/CELIAS Solar EUV Monitor (SEM) has measured absolute EUV solar irradiance nearly continuously over a 15 year period that includes both the cycle 22\\/23 (1996) and cycle 23\\/24 (2008) solar minima. These measurements indicate that irradiance in the 26-34 nm spectral range, including the dominant He II 30.4 nm spectral line, was about 15% ± 6% lower during the

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

2010-01-01

114

Solar Spectral Irradiance Variability in the Near Infrared and Correlations to the Variability of Total Solar Irradiance During the Declining Phase of Solar Cycle 23  

Microsoft Academic Search

The Spectral Irradiance Monitor (SIM) as part of the NASA EOS SORCE mission continuously monitors the solar spectral irradiance (SSI) across the wavelength region spanning the ultraviolet, visible and near infrared (a region encompassing >97% of the TSI measured by the SORCE Total Irradiance Monitor, TIM). These are the first daily measurements from space with the required precision to detect

E. C. Richard; J. W. Harder; J. Fontenla; P. Pilewskie; G. Kopp; T. N. Woods

2007-01-01

115

Application of Solar Spectral Irradiance Variability in a Earth Atmospheric Model  

Microsoft Academic Search

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

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

2010-01-01

116

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion.  

National Technical Information Service (NTIS)

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 sola...

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

2012-01-01

117

Principal Component Analysis of Arctic Solar Irradiance Spectra  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

118

Total Solar Irradiance Data Available for Studying Trends  

NASA Astrophysics Data System (ADS)

The Atmospheric Science Data Center (ASDC) at NASA Langley Research Center archives total solar irradiance (TSI) data from the Active Cavity Radiometer Irradiance Monitor (ACRIM) II and III, Nimbus-7 Earth Radiation Budget (ERB), and Earth Radiation Budget Experiment (ERBE) projects. These data span approximately 27 years and can be used to study trends in solar activity. Some of the goals of ACRIM are to monitor variability of TSI including solar cycles and sunspots and to analyze relationships between TSI and climate change. ACRIM II data are available for October 1991 through August 1997. ACRIM III data are available from April 2000 through the present. Some of the objectives of Nimbus-7 ERB are to obtain accurate measurements of solar irradiance, monitor its variation in time, and to observe the temporal variation of the solar spectrum. The data are available for November 1978 through December 1993. Measurements of the total solar irradiance provide one of the important elements of Earth's radiation budget. These measurements also provide possibilities for "climate experiments" by allowing the sensitivity of the radiation budget to various forcings to be studied empirically. One of those forcings is the variation in the Sun's total energy output which drives our climate system. The ERBE data are available for October 1984 through March 2003. These data along with documentation and read software may be obtained from the NASA Langley ASDC at http://eosweb.larc.nasa.gov.

Morris, K. L.

2005-12-01

119

Extraterrestrial intelligence? The search is on  

NASA Technical Reports Server (NTRS)

NASA's SETI-Microwave Observing Project, beginning on October 12, 1992, will search the closest solar-type stars for radio signals from extraterrestrial civilizations. When completed in the year 2000, the NASA search will have surpassed the search volume of all prior searches by a factor of 10 exp 10. The world's largest radio telescopes will be employed, in conjunction with the NASA Deep Space Network communications antennas. The program will be led by NASA-Ames, with substantial contribution by JPL.

Coulter, Gary R.

1991-01-01

120

1/f noise in the UV solar spectral irradiance  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

121

The Solar Backscatter Ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) experiment  

NASA Technical Reports Server (NTRS)

The SBUV/TOMS is designed to measure the extraterrestrial ultraviolet solar irradiation and the solar ultraviolet radiation from the earth and its atmosphere. Methods to recover the ozone information from backscattered ultraviolet measurements are described. Mapping of the total ozone and 200 mb height fields is obtained.

Heath, D. F.; Krueger, A. J.; Park, H.

1978-01-01

122

Proton irradiated heteroepitaxial InP solar cells  

Microsoft Academic Search

Heteroepitaxial InP solar cells, processed using GaAs substrates, were proton irradiated over the energy range from 0.2 to 10 MeV. Results for carrier removal, cell performance and minority carrier diffusion length were found to be separable into either dislocation dominated or energy dependent categories. High dislocation densities were dominant in determining low pre-irradiation minority carrier diffusion lengths and cell efficiencies.

I. Weinberg; R. K. Jain; C. K. Swartza; H. B. Curtis; D. J. Brinker; C. Vargas-Aburtob; P. J. Drevinsky

1993-01-01

123

Genesis capturing the sun: Solar wind irradiation at Lagrange 1  

NASA Astrophysics Data System (ADS)

Genesis, a member of NASAs Discovery Mission program, is the world's first sample return mission since the Apollo program to bring home solar matter in ultra-pure materials. Outside the protection of Earth's magnetosphere at the Earth-Sun Lagrange 1 point, the deployed sample collectors were directly exposed to solar wind irradiation. The natural process of solar wind ion implantation into a highly pure silicon (Si) bulk composition array collector has been measured by spectroscopic ellipsometry and scanning transmission electron microscopy (STEM). Ellipsometry results show that bulk solar wind ions composed of approximately 95% H +, 4% He + and <1% other elements physically altered the first 59-63 nm of crystalline silicon substrate during 852.8 days of solar exposure. STEM analysis confirms that the solar accelerated ions caused significant strain and visible structural defects to the silicon structure forming a 60-75 nm thick irradiation damage region directly below the surface SiO 2 native oxide layer. Monte Carlo simulations of solar wind H, He, C, O, Ne, Mg, Si and Fe ion collisions in the Si collector with fluences calculated from the Genesis and ACE spacecrafts were used to estimate the energy deposited and Si vacancies produced by nuclear stopping in a flight-like Si bulk array collector. The coupled deposited energy model with the flown Genesis Si in situ measurements provides new insight into the basic principles of solar wind diffusion and space weathering of materials outside Earth's magnetosphere.

Calaway, Michael J.; Stansbery, Eileen K.; Keller, Lindsay P.

2009-04-01

124

Atmospheric temperature responses to solar irradiance and geomagnetic activity  

Microsoft Academic Search

The relative effects of solar irradiance and geomagnetic activity on the atmospheric temperature anomalies (Ta) are examined from the monthly to interdecadal timescales. Geomagnetic Ap (Ap) signals are found primarily in the stratosphere, while the solar F10.7-cm radio flux (Fs) signals are found in both the stratosphere and troposphere. In the troposphere, 0.1–0.4 K increases in Ta are associated with

Hua Lu; Martin J. Jarvis; Hans-F. Graf; Peter C. Young; Richard B. Horne

2007-01-01

125

New Solar Extreme-ultraviolet Irradiance Observations during Flares  

Microsoft Academic Search

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

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

2011-01-01

126

Determinants of skin sensitivity to solar irradiation  

Microsoft Academic Search

Background: Acute effects of UV irradiation include UV-induced erythema. Sunlight plays an important role in the development of skin cancer. Several predictive factors of UV-induced erythema could also be predictive for skin cancer.Objective: Our objective was to quantitatively assess phenotypical and nutritional determinants of sensitivity to UV irradiation, as assessed by the minimal erythema dose (MED).Design: We conducted a cross-sectional

W M R Broekmans; A. A. Vink; E. Boelsma; W. A. A. Klöpping-Ketelaars; L. B. M. Tijburg; P van't Veer; G van Poppel; A. F. M. Kardinaal; AFM Kardinaal

2003-01-01

127

Solar Irradiance Variations and Flare Frequencies during the Interesting Solar Cycle 24  

NASA Astrophysics Data System (ADS)

The current solar cycle 24 has had a slow rise during its first three years, more than a factor of two slower than recent solar cycles. While solar maximum may not have yet been reached for this cycle, the solar irradiance remains significantly lower than the previous cycle 23 maximum level. In spite of a lower activity cycle, there have been episodes of intense and frequent solar storms, such as in February and March 2011. However, these storms appear to be weaker than previous cycles, and a decrease in storm frequency appears to have started back in the late 1990s because the solar flares during solar cycle 23 are about a factor of two less frequent than those in solar cycles 21 and 22. Much of the activity in cycle 24 has been from the solar northern hemisphere, and only recently has the southern hemisphere become more active. This north-south asymmetry in solar activity may influence a slow rise for this cycle, as well as lower activity level, because both hemispheres are not contributing at the same time. These topics will be discussed using data from several different solar irradiance sensors and the GOES X-ray flare monitor over the past four solar cycles.

Woods, T. N.

2012-12-01

128

Analysis of Solar Irradiation Anomalies in Long Term Over India  

NASA Astrophysics Data System (ADS)

India has a high potential for solar energy applications due to its geographic position within the Sun Belt and the large number of cloudless days in many regions of the country. However, certain regions of India, particularly those largely populated, can exhibit large aerosol loading in the atmosphere as a consequence of anthropogenic emissions that could have a negative feedback in the solar resource potential. This effect, named as solar dimming, has already been observed in India, and in some other regions in the world, by some authors using ground data from the last two decades. The recent interest in the promotion of solar energy applications in India highlights the need of extending and improving the knowledge of the solar radiation resources in this country, since most of the long term measurements available correspond to global horizontal radiation and most of them are also located big cities or highly populated areas. In addition, accurate knowledge on the aerosol column quantification and on its dynamical behavior with high spatial resolution is particularly important in the case of India, due to their impact on direct normal irradiation. Long term studies of solar irradiation over India can be performed using monthly means of global hemispheric irradiation measurements from the Indian Meteorological Department. Ground data are available from 1964 till today through the World Radiation Data Centre that publish these values in the web. This work shows a long term analysis of solar irradiation in India using anomalies techniques and trends in ten places over India. Most of the places have exhibit a decreasing trend and negative anomalies confirming thus the darkening effect already reported by solar dimming studies. The analysis of anomalies has also found two periods of different behavior. From 1964 till 1988 the anomalies observed were positive and the last 20 years seems to be a period of negative anomalies. This observation is also consequent with solar dimming effect, apparently increased during the last two decades due to the increase of aerosol loading in the atmosphere. These results remark the important of having accurate knowledge of atmospheric aerosol loading and its dynamics over India with high spatial resolution in the framework of solar energy deployment in the country. It is worth to mention that greater anomalies and a noticeable decreasing trend found in Calcutta could be correlated with the highly population rate, and thus the greater the population density of the area the greater the negative anomalies and the decreasing trend of solar irradiation monthly means.

Cony, M.; Polo, J.; Martin, L.; Navarro, A.; Serra, I.

2012-04-01

129

Long-Term Solar Irradiance Variations Over Solar Cycles 21 to 23  

NASA Astrophysics Data System (ADS)

In this paper we present the work accomplished during the three years long LWS TR&T grant (NAG5-13513). As part of the work we addressed the following questions: (1) How does various total irradiance composites relate to each other? (2) How well various solar indices can be used as surrogates for solar irradiance variations? As part of the research under question (1) we have constructed a new composite using both the Nimbus-7 and ERBS/ERBE total irradiance measurements. While the PMOD composite has shown a symmetrical long-term total irradiance variations with the same maximum and minimum level over the last three consecutive solar cycles, the ACRIM composite has shown a slow 0.05% secular trend from the minimum of cycle~21 to the minimum of cycle~22. Our reconstruction indicates a much smaller trend (about half of the one shown by the ACRIM composite). Our results also show that the linear relation between solar variability, as represented by total irradiance variations, and solar activity, as represented by magnetic indices, breaks down during the maximum and minimum of solar cycles 23. While most of the magnetic indices showed that cycle 23 was a weak cycle, both total and UV irradiances reached as high maxima as during the previous strong cycles. Furthermore, we have found that during the declining portion of cycle 23, total irradiance already reached minimum activity levels, while surrogates used in the empirical models were still in their declining phase. Considering the lack of good surrogates and physical understanding of the underlying mechanisms of irradiance variations, we will address briefly the perspectives of future space-based irradiance experiments.

Pap, J. M.

2006-12-01

130

Soft X-ray Irradiance during a Solar Flare  

NASA Astrophysics Data System (ADS)

Solar soft X-ray irradiance provides a highly variable energy source to the lower thermosphere. Solar flares are a dramatic source of this variability. Observations from the NASA satellite mission Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics - Solar Extreme Ultraviolet Experiment (TIMED-SEE) are being analyzed to determine how the solar soft X-ray energy deposition varies during a solar flare. The XUV Photometer System (XPS) aboard TIMED-SEE observes the solar soft X-ray irradiance between 0.1 and 27 nm for a 3 minute period approximately every 96 minutes. Contrary to initial assumptions based on the nature and infrequency of solar flares, XPS observations have shown that flares significantly impact the daily averaged energy input and thus the atmospheric chemistry of the lower thermosphere. The XPS observed, on average, eight solar flares of various strengths per month during a five month period in 2002 while the Student Nitric Oxide Explorer (SNOE) observed nitric oxide (NO) between 95 and 135 km. It has been shown that SNOE observed a significant increase in NO during the April 21, 2002 solar flare that was observed by the XPS. The eight XPS photodiodes are broadband detectors and a reference spectrum is required to interpret the signal because the sensitivity varies within each detector bandpass. A solar flare spectrum is inferred from the XPS detectors by an algorithm that iterates through differential emission measures until they produce a model spectrum that can reproduce the XPS detector observations. These flare spectra will be used to determine the soft X-ray energy input to Earth's lower thermosphere during a solar flare. Results and a description of this analysis will be presented.

Rodgers, E. M.; Bailey, S. M.; Woods, T. N.; Eparvier, F. G.

2005-05-01

131

[An encounter with extraterrestrial intelligence].  

PubMed

It is much easier to find extraterrestrial intelligence than to detect simple organisms living on other planets. However, it is hard to communicate with such intelligence without the mutual understanding of inter-stellar communication protocol. The radio SETI (The Search for Extra-Terrestrial Intelligence) was initiated with the pioneering work of F. Drake in 1960, one year after the historical SETI paper by Cocconi and Morrison. This talk explains that SETI evolves with two bases of science; the understanding of our universe and the development of technology. Since SETI has had strong connection with radio astronomy from its early beginning, the impacts of radio astronomical findings and technological breakthrough can be seen in many aspects of the SETI history. Topics of this talk include the detection of microwave 3 K background radiation in the universe. Interstellar atomic and molecular lines found in radio-wave spectra provide the evidence of pre-biotic chemical evolution in such region. Radio telescope imaging and spectral technique are closely associated with methodology of SETI. Topics of the talk extend to new Allen Telescope Array and projected Square Kilometer Array. Recent optical SETI and the discoveries of extra solar planets are also explained. In the end, the recent understanding of our universe is briefly introduced in terms of matter, dark matter and dark energy. Even our understanding of the universe has been evolutionarily revolved and accumulated after 1960, we must recognize that our universe is still poorly understood and that astronomy and SETI are required to proceed hand in hand. PMID:15136757

Hisabayashi, Hisashi

2003-12-01

132

Measured and modeled trends in solar spectral irradiance variability in the visible and infrared  

Microsoft Academic Search

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). This instrument monitored the descending phase of solar cycle 23 and is now continuing these observations in the rising phase of cycle 24. The SIM observations clearly show rotational modulation of spectral irra-diance due to the

Jerald Harder; Juan Fontenla; Mark Rast; Peter Pilewskie; Thomas Woods

2010-01-01

133

The Improved Solar Irradiance Platform (SIP) using SDO EVE data  

NASA Astrophysics Data System (ADS)

The Solar Irradiance Platform (SIP) produces the variable, full solar spectrum in assorted spectral formats for historical, nowcast, and forecast applications. In addition, it produces an array of solar irradiance and thermospheric proxies. SIP has recently been upgraded to v2.37 and now provides improved Lyman-alpha (121.6 nm) reporting for nearly 6 solar cycles. Accurate values of H Lyman-alpha are important for modeling solar chromospheric emissions as well as understanding solar system phenomena such as planetary corona and interstellar hydrogen abundances. The Lyman-alpha values rely on a composite of measurements and modeling results, all scaled to the commonly accepted reference level from the Upper Atmosphere Research Satellite (UARS) and extended by NASA's Solar Dynamics Observatory (SDO) Extreme ultraviolet Variability Experiment (EVE) measurements. In particular, v2.37 uses an updated running linear regression with the Mg II core-to-wing ratio as a proxy to obtain Lyman-alpha values for unavailable days.

Bouwer, S.; Bailey, J. J.; Tobiska, W.

2011-12-01

134

Solar irradiance variability: progress in measurement and empirical analysis  

NASA Astrophysics Data System (ADS)

Here we report the progress in both measurements and analysis of total solar irradiance (TSI) during the last 24 years. Recent TSI measurements made by ACRIM III and VIRGO in the last two years agree to within 0.5 W m -2 and show the same pattern of short-term variability. A 24-year composite record of TSI measurements gives estimates of its variation for two solar cycles. Such composites give the first estimates of secular variation of the solar output. Our analysis of TSI data from solar minimum to maximum for cycles 22 and 23 gives nearly identical regression equations because of improvement in VIRGO degradation corrections, thus, resolving the empirical issue raised by de Toma et al. [Astrophys. J. Lett. 549 (2001) L131]. This agreement occurs despite a decrease in cycle 23 of sunspot number by ?33% below solar maximum values for cycles 21 and 22.

de Toma, G.; White, O. R.; Chapman, G. A.; Walton, S. R.

2004-01-01

135

Aircraft observations of the solar ultraviolet irradiance throughout the troposphere  

Microsoft Academic Search

Observations of the biological effective solar ultraviolet irradiance, made by instrumentation flown on a Falcon aircraft over the entire Greek area, from the sea up to the tropopause level, obtained in the frame of the Radiation Field in the Troposphere-Scientific Training and Access to Aircraft for Atmospheric Research Throughout Europe project, are presented to discuss among others its altitude dependence.

C. Varotsos; D. Alexandris; G. Chronopoulos; C. Tzanis

2001-01-01

136

SORCE and Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

137

Forbush decreases, solar irradiance variations, and anomalous cloud changes  

NASA Astrophysics Data System (ADS)

Changes in the galactic cosmic ray (GCR) flux due to variations in solar activity may provide an indirect connection between the Sun's and the Earth's climates. Epoch superpositional (composite) analyses of high-magnitude GCR fluctuations, known as Forbush decrease (FD) events, have been widely used to test this hypothesis, with varied results. This work provides new information regarding the interpretation of this approach, suggesting that FD events do not isolate the impacts of GCR variations from those of solar irradiance changes. On average, irradiance changes of ˜0.4 W m-2 outside the atmosphere occur around 2 days in advance of FD-associated GCR decreases. Using this 2 day gap to separate the effects of irradiance variations from GCR variations on cloud cover, we demonstrate small, but statistically significant, anomalous cloud changes occurring only over areas of the Antarctic plateau in association with the irradiance changes, which previous workers had attributed to GCR variations. Further analysis of the sample shows that these cloud anomalies occurred primarily during polar darkness, precluding the possibility of a causal link to a direct total solar irradiance effect. This work suggests that previous FD-based studies may have ineffectively isolated the impacts of GCR variations on the Earth's atmosphere.

Laken, Benjamin; Kniveton, Dominic; Wolfendale, Arnold

2011-05-01

138

Reconstructing the Solar VUV Irradiance over the Past 60 Years  

NASA Technical Reports Server (NTRS)

The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at I nm spectral resolution and on a 1-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric models, as well as climate studies over 60 years. A brief overview of the FISM model will be given, and also discussed is how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM and its accuracies. Results will also be shown quantifying the VUV contributions to the total flare energy budget, and more importantly discuss the increased errors associated by not including flares in the solar energy input to the Earth's system. Concluding the talk will be a discussion of the proxies, and their associated uncertainties, used for solar spectral reconstructions prior to 1947 going back hundreds of years.

Chamberlin, Phillip

2010-01-01

139

EUV-PHOKA measurements of solar spectral irradiance variations in the EUV\\/XUV region  

Microsoft Academic Search

The Extreme Ultraviolet Photocathode Experiment EUV-PHOKA measures solar spectral irradiance in six windows between 1 and 130 nm. The authors determine absolute calibrated intensities with a time resolution between fractions of a second (flare mode and occultation measurements) and 10 s. Their scientific goals are the investigation of solar eruptive processes, solar irradiance variations in relation to solar activity, and

K. Pflug; Yu. D. Kotov; G. Schmidtke

1996-01-01

140

Variations of solar spectral irradiance from near UV to the infrared-measurements and results  

NASA Astrophysics Data System (ADS)

Solar spectral irradiance variations are known to exhibit a strong wavelength dependence with the amount of variability increasing towards shorter wavelengths. The bulk of solar radiation is emitted at visible and infrared wavelengths. Thus, the spectral radiation length of 300nm accounts for 99% of the total solar radiative output. Deposited in the Earth's troposphere and biosphere, this part of the solar irradiance spectrum determines direct solar radiative forcing and is therefore of particular interest for climate studies. First, measurements of solar irradiance and irradiance variability from near UV to the IR are reviewed with particular emphasis on the results obtained from the Variability of Irradiance and Gravity Oscillations (VIRGO) on SOHO and Solar Spectrum Measurement (SOLSPEC) instruments. In the second part a model is presented which describes solar spectral irradiance variations in terms of the changing distribution of solar surface magnetic features.

Fligge, M.; Solanki, S. K.; Pap, J. M.; Fröhlich, C.; Wehrli, C.

2001-09-01

141

Annealing characteristics of irradiated hydrogenated amorphous silicon solar cells  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

142

Solar irradiance, cosmic rays and cloudiness over daily timescales  

NASA Astrophysics Data System (ADS)

Although over centennial and greater timescales solar variability may be one of the most influential climate forcing agents, the extent to which solar activity influences climate over shorter time periods is poorly understood. If a link exists between solar activity and climate, it is likely via a mechanism connected to one (or a combination) of the following parameters: total solar irradiance (TSI), ultraviolet (UV) spectral irradiance, or the galactic cosmic ray (GCR) flux. We present an analysis based around a superposed epoch (composite) approach focusing on the largest TSI increases and decreases (the latter occurring in both the presence and absence of appreciable GCR reductions) over daily timescales. Using these composites we test for the presence of a robust link between solar activity and cloud cover over large areas of the globe using rigorous statistical techniques. We find no evidence that widespread variations in cloud cover at any tropospheric level are significantly associated with changes in the TSI, GCR or UV flux, and further conclude that TSI or UV changes occurring during reductions in the GCR flux are not masking a solar-cloud response. However, we note the detectability of any potential links is strongly constrained by cloud variability.

Laken, Benjamin A.; ?alogovi?, Jasa

2011-12-01

143

Volcanic ash - Terrestrial versus extraterrestrial  

NASA Technical Reports Server (NTRS)

A principal difference between terrestrial and extraterrestrial lavas may consist in the greater ability of terrestrial lavas to form thin films (like those of soap bubbles) and hence foams. It would follow that, in place of the pumice and spiny shards found in terrestrial volcanic ash, an extraterrestrial ash should contain minute spherules. This hypothesis may help to explain lunar microspherules.

Okeefe, J. A.

1976-01-01

144

The search for extraterrestrial intelligence  

Microsoft Academic Search

As far as we know, humanity is alone in the Universe: there is no definite evidence for the existence of extraterrestrial life, let alone extraterrestrial civilizations (ETCs) capable of communicating or travelling over interstellar distances. Yet popular speculation about the existence of ETCs abounds, including reports of alien visitations either now or in the past. But there is a middle

T. L. Wilson

2001-01-01

145

Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow  

NASA Technical Reports Server (NTRS)

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 Radiation Facility (SURF) at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland.

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

1993-01-01

146

Evaluating Ground-based Proxies for Solar Irradiance variation  

NASA Astrophysics Data System (ADS)

In order to determine what ground-based proxies are best for evaluating solar irradiance variation before the advent of space observations, it is necessary to test these proxies against space observations. We have tested sunspot number, total sunspot area, and sunspot umbral area against the Nimbus-7 measurements of total solar irradiance variation over the eleven year period 1980-1990. The umbral area yields the best correlation and the total sunspot area yields the poorest. Reasons for expecting the umbral area to yield the best correlation are given, the statistical procedure followed to obtain the results is described, and the value of determining the best proxy is discussed. The latter is based upon the availability of an excellent database from the Greenwich Observatory obtained over the period 1876-1976, which can be used to estimate the total solar irradiance variation before sensitive space observations were available. The ground-based observations used were obtained at the Coimbra Solar Observatory. The analysis was done at Goddard using these data and data from the Nimbus-7 satellite.

Jordan, S. D.; Garcia, M. A.

2003-05-01

147

Trends in solar spectral irradiance variability in the visible and infrared  

Microsoft Academic Search

The Spectral Irradiance Monitor (SIM) on-board the Solar Radiation and Climate Experiment (SORCE) satellite provides the first multi-year continuous measurements of solar spectral irradiance (SSI) variability from 200–2400 nm, accounting for about 97% of the total solar irradiance (TSI). In addition to irradiance modulation from active region passage, the SSI values for wavelengths with a brightness temperature greater than 5770

Jerald W. Harder; Juan M. Fontenla; Peter Pilewskie; Erik C. Richard; Thomas N. Woods

2009-01-01

148

Effect of solar irradiation on extracellular enzymes of Aeromonas proteolytica  

NASA Technical Reports Server (NTRS)

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.

Foster, B. G.

1973-01-01

149

Properties of solar gravity mode signals in total irradiance observations  

SciTech Connect

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.

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

1988-01-01

150

An Improved Total Solar Irradiance Climate Data Record  

NASA Astrophysics Data System (ADS)

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.

Kopp, G.

2011-12-01

151

Total solar irradiance at Table Mtn, California 1926-77  

NASA Technical Reports Server (NTRS)

It is suggested that the mean direct solar irradiance at Table Mountain, California (100 km NE of Los Angeles at an elevation of 2460 m) in July over the 1926-77 period has not changed by more than the standard errors associated with the means of the observations. Data were not collected systematically in the years between 1952 and 1977. If the conclusion which is based partly on a single month of observation in 1977 is valid, change in the atmospheric transmission-solar 'constant' product does not exceed plus or minus one percent.

Wilson, R. C.; Butler, C. P.

1978-01-01

152

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

153

Temperature dependence of damage coefficient in electron irradiated solar cells  

NASA Technical Reports Server (NTRS)

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.

Faith, T. J.

1973-01-01

154

Recent changes in solar irradiance in Antarctica  

SciTech Connect

A significant decrease in the annual sums of global irradiance reaching the surface in Antarctica, averaging -0.28 W m{sup -2} yr{sup -1}, was derived from an analysis of all complete years of measurement available from 12 pyranometer stations, 10 of which were on the coast. The decrease was greater than could be attributed to the nonhomogeneous nature of the database, the estimated errors of measurement, or changes in the amount of cloud cover. The smaller database of radiation balance measurements available showed no statistically significant change. Possible causes of these results are discussed, as is the implication that the recent surface warming in Antarctica is not due to radiative forcing. 49 refs., 3 figs., 5 tabs.

Stanhill, G.; Cohen, S. [Institute of Soils and Water, Bet Dagan (Israel)] [Institute of Soils and Water, Bet Dagan (Israel)

1997-08-01

155

Influence of solar UVA on erythemal irradiances  

NASA Astrophysics Data System (ADS)

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° to 80° 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.

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

2006-06-01

156

A model of solar total and spectral irradiance variations  

Microsoft Academic Search

We model solar spectral irradiance variations under the assumption that they are produced by sunspots and faculae alone. The model is based on three components, i.e. quiet Sun, assumed to be temporally invariant, sunspots and faculae whose temporal variations are mimicked using time series of sunspot areas and Mg II core-to-wing ratios. The detailed flux spectrum for each component is

M. Fligge; S. K. Solanki; Y. C. Unruh; C. Frohlich

1998-01-01

157

On the Relation Between Solar Activity and Clear-Sky Terrestrial Irradiance  

NASA Astrophysics Data System (ADS)

The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958 - 2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance data exhibit a marked seasonal cycle, extended periods of lower irradiance due to emissions of volcanic aerosols, and a long-term decrease in atmospheric transmission independent of solar activity. After correcting for these effects, it is found that clear-sky terrestrial irradiance typically varies by ? 0.2±0.1 % over the course of the solar cycle, a change of the same order of magnitude as the variations of the total solar irradiance above the atmosphere. An investigation of changes in the clear-sky atmospheric transmission fails to find a significant trend with sunspot number. Hence there is no evidence for a yet unknown effect amplifying variations of clear-sky irradiance with solar activity.

Feulner, G.

2013-02-01

158

Creation of a Composite Solar Ultraviolet Spectral Irradiance Data Set  

NASA Astrophysics Data System (ADS)

Solar ultraviolet (UV) irradiance is deposited in the atmosphere at altitudes ranging from the lower stratosphere to the lower thermosphere. Understanding the spectral and temporal dependence of solar UV variations is thus critical to characterizing the long-term terrestrial energy input over a wide vertical region. Regular spectral solar UV measurements from space began in late 1978 with the Nimbus-7 SBUV instrument, and have continued to the present using overlapping data sets from multiple instruments (SME, SBUV/2 on NOAA satellites, SUSIM and SOLSTICE on UARS). However, wavelength-dependent absolute biases and drifts are observed when any two data sets are compared. We are developing a composite spectral irradiance data set covering the wavelength range 120-400 nm for the period 1978-2004 as part of the Living With a Star Targeted Research and Technology program. We will describe the methods being used to evaluate and merge the individual data sets, and the status of the project. This work is being done in collaboration with the respective instrument scientists from each mission to ensure that the final product is accurate. The composite UV irradiance data set produced by this project will be extended into the future using data from the SOLSTICE and SIM instruments on the SORCE mission.

Deland, M. T.; Cebula, R. P.

2006-12-01

159

Total solar irradiance in Maunder minimum derived from 14C record  

NASA Astrophysics Data System (ADS)

Maunder Minimum provide a critical check on the influence of solar variation on climate. Some previous studies show the total solar irradiance change from 0.5 W/m2 to 1.5 W/m2 based on sunspot number and possible evolution effect on Sun-like stars. A major faults of this method is sunspot number can only lower to 0, where total solar irradiance can be lower! This study tries to evaluate the effect from 1 4C record and reconstruct the expected sunspot number, which can be negative; then reconstructed total solar irradiance from modern measurements of total solar irradiance and sunspot numbers.

Huang, Ming-Huey A.

160

Solar Bolometric Imager for Investigating the Sources of Solar Irradiance Variability  

NASA Astrophysics Data System (ADS)

The Solar Bolometric Imager is an innovative instrument for the investigation of the sources of solar irradiance variability. It makes precise, wavelength-integrated, photometric measurements of the irradiance variations originating in the solar photosphere. It provides images with spectrally flat response over the range 200-2600 nm, which includes about 95% of the total solar irradiance (TSI). It is important to realize that the SBI measures broad band contrast of thermal structures relative to their surroundings, so it does not require absolute accuracy or even high long term reproducibility. Its angular resolution (1 arcsecs/pixel) and field of view (320x240 arcsecs) are optimized to discriminate between TSI contributions from different magnetic and non-magnetic solar regions. The detector is an uncooled bolometric array with 320x240 ferro-electric pixels, coated with gold-black to achieve uniform sensitivity at all wavelengths of incident light. We are in the process of developing a space based SBI that builds upon the heritage of a stratospheric balloon-borne instrument successfully flown in 2003, and 2007. A space-based SBI will directly attack one of the most challenging problems in solar research: “What are the origins of long term solar total output variation on centennial and millennial time scales?” In addition, SBI measurements will continue to increase our understanding of solar magneto-convection, and more generally the underlying physics of solar magnetic variability. Here we present the results of our latest instrument development efforts aimed at bringing the current SBI prototype to a Technology Readiness Level suitable for a SMEX or a Mission of Opportunity.

Bernasconi, Pietro N.; Foukal, P. V.

2012-05-01

161

Effects of solar UV irradiation on dynamics of ozone hole in Antarctica  

Microsoft Academic Search

To study relationship between changes in solar ultraviolet (UV) irradiance and dynamics of the Antarctic ozone hole during the final breakup of the Antarctic polar vortex the composite Mg II index has been used as a proxy for the solar UV irradiance. The short-term changes in the UV-irradiation have been separated after removing the long- and middle term variations. Examination

O. Troshichev; I. Gabis

2005-01-01

162

Estimating Solar Irradiance using a Geostationary Satellite  

NASA Astrophysics Data System (ADS)

A method to estimate global horizontal irradiance (GHI) at the surface using a geostationary satellite is presented. The spatial variation of ground and cloud albedo of California is characterized in the 0.55-0.75 im wavelength spectral region by analyzing a series of images from the visible channel on the GOES West satellite. Using these two characteristic albedo maps a cloud index is generated for each pixel in subsequent images as an estimate of the cloud fraction in that pixel. The cloud index is converted into a clear sky index which is then coupled with the modeled GHI under a clear sky to generate estimates of the GHI under the current cloud conditions. The model was applied to 914 images over 65 days and validated with ground truth measurements in California. The mean bias difference from 119 stations in the California Irrigation Management Information System was 6.7 W/m 2 (3.2%) and the root mean square difference was 78.6 W/m2 (21.9%) which is consistent with previously reported results for satellite algorithms. A Matlab-Java code to execute the model is documented.

Urquhart, Bryan Glenn

163

Curating NASA's extraterrestrial samples—Past, present, and future  

Microsoft Academic Search

The NASA Johnson Space Center Astromaterials Acquisition and Curation Office has the unique responsibility to curate NASA's extraterrestrial samples – from past and forthcoming missions – into the indefinite future. Presently curation includes documentation, preservation, preparation, and distribution of samples from the Moon, asteroids, comets, the solar wind, and the planet Mars. Each of these sample sets has a unique

Carlton Allen; Judith Allton; Gary Lofgren; Kevin Righter; Michael Zolensky

2011-01-01

164

Nuclear power--key to man's extraterrestrial civilization  

Microsoft Academic Search

The start of the Third Millennium will be highlighted by the establishment of man's extraterrestrial civilization with three technical cornerstones leading to the off-planet expansion of the human resource base. These are the availability of compact energy sources for power and propulsion, the creation of permanent manned habitats in space, and the ability to process materials anywhere in the Solar

J. A. Angelo; D. Buden

1982-01-01

165

Spectral irradiance curve calculations for any type of solar eclipse  

NASA Technical Reports Server (NTRS)

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.

Deepak, A.; Merrill, J. E.

1974-01-01

166

Iterative filtering of ground data for qualifying statistical models for solar irradiance estimation from satellite data  

Microsoft Academic Search

A new technique of filtering solar radiation ground data is proposed for generating models for solar irradiance estimation from geostationary satellite data. The filtering processes consists of an iterative way of selecting the training data set to achieve the best model response. Although in this paper the proposed methodology has been used for solar irradiance modeling, it could be applied

Jesus Polo; Luis F. Zarzalejo; Lourdes Ramirez; Bella Espinar

2006-01-01

167

Analysis of non-uniformity of irradiance measurement uncertainties of a pulsed solar simulator  

NASA Astrophysics Data System (ADS)

The conversion efficiency measurement accuracy of solar cell is heavily rely on the measurement uncertainty of pulsed solar simulator. The measurement uncertainty assessment method of pulsed solar simulator is widely analyzed and studied. This paper describes uncertainty assessment method of measurement of irradiance non-uniformity which is one of the three most important factors(spectral mismatch, non-uniformity of irradiance and instability of irradiance) influencing pulsed solar simulator measurement uncertainties. An experiment using a real pulsed solar simulator was performed to testify the validity of uncertainty assessment method. The results provide a theoretical and data basis for further analysis of overall uncertainties of solar simulators.

He, Yingwei; Xiong, Limin; Meng, Haifeng; Zhang, Junchao; Liu, Dingpu; Zhang, Jieyu

2012-11-01

168

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

169

A criterion study of solar irradiation patterns for the performance testing of thermosyphon solar water heaters  

Microsoft Academic Search

A Taiwan test standard was established in 1989 using outdoor daily efficiency test methods. This test standard has been implemented for 12 years with satisfactory results. However, it was also found from field applications that the pattern of solar irradiation would affect the result of the performance test. In the present study, we used a distribution factor Ri defined as

J. M Chang; M. C Shen; B. J Huang

2002-01-01

170

Variability of the solar spectral irradiance and energetic particles  

NASA Astrophysics Data System (ADS)

The total spectral irradiance of the Sun is seen to vary on many time scales. Three timescales are more prominent: (1) the longest one of about 11 years; (2) an intermediate timescale of the order of a few weeks; and (3) the shortest variation from hours to seconds. Every 11 years, the total solar irradiance periodically shows intervals of great activity and periods of almost no activity. The peak to peak variability, however, is less than 0.1%. This periodic variation of 11 years is called the solar cycle, which main tracer are sunspots. During times of maximum activity, there are many sunspots on the surface of the Sun, whereas during minimum there may be none. Sunspots are dark, and therefore cool, regions of enhanced magnetic fields of about a few hundred Gauss, that usually appear in groups on the solar photosphere. Basically, the solar cycle is regulated by the magnetic dynamo acting below the solar surface. Right now, the Sun is going through a time of minimum activity. The sunspot lifetime is of the order of one to two weeks, and are thus responsible for the intermediate variability timescale. The magnetic loops seen in ultraviolet and X-ray images have their footpoints anchored on sunspots. The most energetic phenomena of solar activity are flares and coronal mass ejections. Flares are large explosions that occur on the solar atmosphere and may last from a few seconds to hours. A solar flare is caused by a sudden, and yet unpredicted, energy release high above the magnetic loops. This magnetic energy is then used into particle acceleration and heating of the surrounding atmosphere. Both the energetic particles and the hot gas produce emission throughout the whole electromagnetic spectrum, from the very energetic gamma-rays all the way to long radio waves. From the observation of the emission produced during flares it is possible to infer the energetic particles spectra and thus have a clue on the acceleration mechanism that produced these particles. The recent findings of flare observations at gamma-rays by the RHESSI satellite and at high radio frequencies by the Solar Submillimeter Telescope are presented and discussed.

Silva-Válio, Adriana

2010-02-01

171

Uncertainty of measurements of spectral solar UV irradiance  

NASA Astrophysics Data System (ADS)

Most investigations on the nature and effects of solar ultraviolet (UV) radiation at the Earth's surface require measurements of high accuracy combined with well-defined procedures to assess their quality. Here we present a general evaluation of all relevant errors and uncertainties associated with measurements of spectral global irradiance in the UV. The uncertainties are quantified in terms of dependence of the characteristics of the spectroradiometer, the uncertainty of calibration standards, the solar zenith angle, and atmospheric conditions. The methodologies and equations presented can be applied to most spectroradiometers currently employed for UV research. The sources of error addressed include radiometric calibration, cosine error, spectral resolution, wavelength misalignment, stability, noise, stray light, and timing errors. The practical application of the method is demonstrated by setting up a complete uncertainty table for the mobile spectroradiometer of the Fraunhofer Institute for Atmospheric Environmental Research (IFU). This instrument has successfully participated in several international intercomparisons of UV spectroradiometers. The expanded uncertainty (coverage factor k=2) for measurements of global spectral irradiance conducted with this instrument varies between 6.3% in the UVA and 12.7% at 300 nm and 60° solar zenith angle. The expanded uncertainties in erythemally and DNA weighted irradiances are 6.1% and 6.6%, respectively. These expanded uncertainties are comparable to uncertainties at the 2? level in conventional statistics. A substantial reduction of these uncertainties would require smaller uncertainties in the irradiance standards used to calibrate the instrument. Though uncertainties caused by wavelength misalignment and noise become prominent in the shortwave UVB, which is the most important spectral range for UV trend detection, the results indicate that the accuracy of the IFU radiometer is sufficient to detect long-term trends in UV arising from a 3% change in atmospheric ozone. The detection of trends caused by a 1% change in ozone may be beyond the capabilities of current instrumentation.

Bernhard, G.; Seckmeyer, G.

172

Analysis of Cumulus Solar Irradiance Reflectance (CSIR) Events  

NASA Technical Reports Server (NTRS)

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.

Laird, John L.; Harshvardham

1996-01-01

173

Spectral Solar Irradiance over Solar Cycle 23 from Sunphotometers of VIRGO on SOHO (Invited)  

NASA Astrophysics Data System (ADS)

Within the VIRGO experiment on SOHO two 3-channel sunphotometers (SPM) measure solar spectral irradiance at 402, 500 and 862 nm with a bandwidth (FWHM) of 5 nm. The time series cover the period from April 1996 until present, more than 14 years and a full solar cycle from the minimum in 1996 to the one in late 2008. SPMA measures the irradiance continuously with a 1-minute sampling and after being exposed to the sun during more than 14 years the sensitivities of the red, green and blue channels are at 74.1, 24.3 and 7.1 percent of their first light values, respectively. SPMB, is exposed rarely and is used to monitor degradation; the result of a detailed analysis of these data can then be used to correct SPMA for long-term changes and degradation effects. These are determined by a degradation model and the result shows that the changes due to exposure to the sun depend not only on the exposure time and the cumulated dose of radiation received, but also on the temperature of the instrument (Boltzmann factor). This indicates that simple degradation corrections by e.g. fitting multi-degree polynomials may not be adequate. The result of this detailed analysis are reliable time series of solar spectral irradiance at the three wavelengths. The results confirm the positive correlation of all three channels with solar activity and TSI, which is in contrast to the results from SIM on SORCE - at least for the green channel. A possible long-term trend of the spectral irradiance is also discussed in comparison with the behaviour of total solar irradiance (TSI).

Frohlich, C.

2010-12-01

174

The Extraterrestrial Life Debate from Antiquity to 1900  

NASA Astrophysics Data System (ADS)

This chapter provides an overview of the Western historical debate regarding extraterrestrial life from antiquity to the beginning of the twentieth century. Though schools of thought in antiquity differed on whether extraterrestrial life existed, by the Middle Ages, the Aristotelian worldview of a unified, finite cosmos without extraterrestrials was most influential, though there were such dissenters as Nicholas of Cusa. That would change as the Copernican revolution progressed. Scholars such as Bruno, Kepler, Galileo, and Descartes would argue for a Copernican system of a moving Earth. Cartesian and Newtonian physics would eventually lead to a view of the universe in which the Earth was one of many planets in one of many solar systems extended in space. As this cosmological model was developing, so too were notions of extraterrestrial life. Popular and scientific writings, such as those by Fontenelle and Huygens, led to a reversal of fortunes for extraterrestrials, who by the end of the century were gaining recognition. From 1700 to 1800, many leading thinkers discussed extraterrestrial intelligent beings. In doing so, they relied heavily on arguments from analogy and such broad principles and ideas as the Copernican Principle, the Principle of Plenitude, and the Great Chain of Being. Physical evidence for the existence of extraterrestrials was minimal, and was always indirect, such as the sighting of polar caps on Mars, suggesting similarities between Earth and other places in the universe. Nonetheless, the eighteenth century saw writers from a wide variety of genres—science, philosophy, theology, literature—speculate widely on extraterrestrials. In the latter half of the century, increasing research in stellar astronomy would be carried out, heavily overlapping with an interest in extraterrestrial life. By the end of the eighteenth century, belief in intelligent beings on solar system planets was nearly universal and certainly more common than it would be by 1900, or even today. Moreover, natural theology led to most religious thinkers being comfortable with extraterrestrials, at least until 1793 when Thomas Paine vigorously argued that although belief in extraterrestrial intelligence was compatible with belief in God, it was irreconcilable with belief in God becoming incarnate and redeeming Earth's sinful inhabitants. In fact, some scientific analyses, such as Newton's determination of the comparative masses and densities of planets, as well as the application of the emerging recognition of the inverse square law for light and heat radiation, might well have led scientists to question whether all planets are fully habitable. Criticism would become more prevalent throughout the nineteenth century, and especially after 1860, following such events as the "Moon Hoax" and Whewell's critique of belief in extraterrestrials. Skepticism about reliance on arguments from analogy and on such broad metaphysical principles as the Principle of Plenitude also led scientists to be cautious about claims for higher forms of life elsewhere in the universe. At the start of the twentieth century, the controversy over the canals of Mars further dampened enthusiasm for extraterrestrials. By 1915 astronomers had largely rejected belief in higher forms of life anywhere in our solar system and were skeptical about the island universe theory.

Crowe, Michael J.; Dowd, Matthew F.

175

Forecast Method of Solar Irradiance with Just-In-Time Modeling  

NASA Astrophysics Data System (ADS)

PV power output mainly depends on the solar irradiance which is affected by various meteorological factors. So, it is required to predict solar irradiance in the future for the efficient operation of PV systems. In this paper, we develop a novel approach for solar irradiance forecast, in which we introduce to combine the black-box model (JIT Modeling) with the physical model (GPV data). We investigate the predictive accuracy of solar irradiance over wide controlled-area of each electric power company by utilizing the measured data on the 44 observation points throughout Japan offered by JMA and the 64 points around Kanto by NEDO. Finally, we propose the application forecast method of solar irradiance to the point which is difficulty in compiling the database. And we consider the influence of different GPV default time on solar irradiance prediction.

Suzuki, Takanobu; Goto, Yusuke; Terazono, Takahiro; Wakao, Shinji; Oozeki, Takashi

176

Browsing, Understanding, and Accessing Solar Irradiance Data via LISIRD  

NASA Astrophysics Data System (ADS)

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 just by integrating new data sets, but also by improving its data management and presentation. This means assigning unique identifiers to data sets and the granules that constitute them, which will support better identification and citation of our data sets. We will explore identification issues and solutions related to the dynamic generation of new data sets enabled by LaTiS. We are also improving the access to our metadata, including semantically enabling the site so that our data can be discovered, related concepts can be explored, our inventory can be browsed and searched, and our data understood well enough to be understood and used appropriately. This poster will describe the current state of LISIRD, provide details of the data sets it serves, demonstrate the role of the LaTiS middleware, discuss the assignment of unique identifiers to our data products, describe plans for integration of a semantically metadata database, and address other related aspects of serving spectral and other time series data.

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

2012-12-01

177

Recent advances in observations and modeling of the solar ultraviolet and X-ray spectral irradiance  

Microsoft Academic Search

There have been significant, recent advances in understanding the solar ultraviolet (UV) and X-ray spectral irradiance from several different satellite missions and from new efforts in modeling the variations of the solar spectral irradiance. The recent satellite missions with solar UV and X-ray spectral irradiance observations include the X-ray Sensor (XRS) aboard the series of NOAA GOES spacecraft, the Upper

Thomas N. Woods

2008-01-01

178

New Technique for Predicting Silicon Solar Cell Short-Circuit Currents at Reference-Irradiance Conditions.  

National Technical Information Service (NTIS)

A combined analytical/experimental technique for the prediction of silicon solar cell short circuit currents at any reference irradiance condition has been developed. Concurrent short-circuit current and spectral irradiance measurements are used to comput...

D. R. Lorentz C. E. Backus

1981-01-01

179

Solar cycle variability of the total solar irradiance (TSI) out-of-the-ecliptic plane  

NASA Astrophysics Data System (ADS)

Variations of the Total Solar Irradiance (TSI) are expected to arise due to the presence and evolution of bright (faculae and active network) and dark (sunspots) structures on the solar surface. Space-based measurements, which have been realized since 1978, indicate that the TSI varies up to 0.4% on daily time scale and approximately 0.1% from minimum to maximum of solar activity. These observations suggest that the Sun is subdued in photometric variability compared to its stellar analogs. However, as these measurements of the solar irradiance are limited to a region near the solar equator, which is not necessarily the case for other stars. Consequently, any latitudinal asymmetry in the flux density is not taken into account in these comparisons. Here we show that the variability of the solar irradiance depends on the latitude of the observer. we have investigated the variability of the flux density out-of-the-ecliptic that was previously modeled employing a physics-based model based on the distribution of magnetic concentrations on the solar surface. In order to investigate the dependence of the time scale and timing of the variations on the latitude, we have decomposed the time series for each latitude using the discrete wavelet transform based on the orthonormal Daubechies kernel of order 5 (db5). We estimate that the range of daily variations of the flux density in the equatorial region is from 1356.2 to 1363.4 Wm-2, while the variation near the poles is approximately 1.8 Wm-2. This happens because the effect of bright elements (faculae and active network) extends farther toward the poles than the depletions caused by sunspots. The uncertainties are also discussed in details. This work is partially supported by CNPq under grant agreement no. 312488/2012-2 and by FAPESP under the grant agreement no. 2008/58161-1 (PFPMCG - Projeto Temático) and no. 2011/13976-0.

Vieira, L.; Da Silva, L. A.; Prestes, A.; Dal Lago, A.

2013-05-01

180

Effects of the solar spectral irradiance changes during the first half of 20th century on chemistry and climate  

Microsoft Academic Search

The attribution of climate and chemistry changes in the past requires understanding of the role of different natural forcing such as volcanic eruptions and solar irradiance. The first half of the 20th century is characterized by an increase in solar activity (and presumably solar irradi-ance) reaching the maximum in the year 1957. Therefore, to elucidate the contribution of the solar

Eugene Rozanov; Davos Dorf; F. Arfeuille; S. Brünnimann; M. Calisto; T. Egorova; A. Fischer; P. Heckendorn; B.-P. Luo; T. Peter; A. V. Shapiro; W. Schmutz; M. Schraner; A. Stenke; V. Zubov

2010-01-01

181

[Extraterrestrial influences on health and disease].  

PubMed

As to extraterrestrial influences on man in health and disease so far only the effect of the sun and moon are known. This concerns the effect of solar radiation of different wavelengths and the effect of corpuscular solar radiation which has an impact on the condition of the terrestrial magnetic field and electric conditions in the atmosphere. Moreover there is also a question of important influences of gravitation (tides). Here the influence of the position of the moon in relation to the connecting line between sun and earth is involved. In the course of the synodic month (from new moon to the next new moon) a semilunar periodicity of different medical and geomagnetic indicators as well as meteorological ones plays a part. Based on his own research and that of others the author reaches the conclusion that extraterrestrial and terrestrial influences are interrelated and exert a mutual influence on each other and that it is not sensible to separate them strictly. Investigation of all the mentioned influences is important not only for biomedical prognosis but also for basic geophysical and meteorological research. Perspectively it would be useful to plan model experiments. The author feels it is his duty to refuse publication of different horoscopes in the mass media, whatever the intention. In the lay public this may lead to popularization of astrology which has nothing in common with serious research. PMID:8137381

Sitar, J

1994-02-14

182

Extraterrestrial magnetic minerals  

NASA Astrophysics Data System (ADS)

Thermomagnetic and microprobe analyses are carried out and a set of magnetic characteristics are measured for 25 meteorites and 3 tektites from the collections of the Vernadsky Geological Museum of the Russian Academy of Sciences and Museum of Natural History of the North-East Interdisciplinary Science Research Institute, Far Eastern Branch of the Russian Academy of Sciences. It is found that, notwithstanding their type, all the meteorites contain the same magnetic minerals and only differ by concentrations of these minerals. Kamacite with less than 10% nickel is the main magnetic mineral in the studied samples. Pure iron, taenite, and schreibersite are less frequent; nickel, various iron spinels, Fe-Al alloys, etc., are very rare. These minerals are normally absent in the crusts of the Earth and other planets. The studied meteorites are more likely parts of the cores and lower mantles of the meteoritic parent bodies (the planets). Uniformity in the magnetic properties of the meteorites and the types of their thermomagnetic (MT) curves is violated by secondary alterations of the meteorites in the terrestrial environment. The sediments demonstrate the same monotony as the meteorites: kamacite is likely the only extraterrestrial magnetic mineral, which is abundant in sediments and associated with cosmic dust. The compositional similarity of kamacite in iron meteorites and in cosmic dust is due to their common source; the degree of fragmentation of the material of the parent body is the only difference.

Pechersky, D. M.; Markov, G. P.; Tsel'movich, V. A.; Sharonova, Z. V.

2012-07-01

183

Extraterrestrial Fluvial Channel Patterns  

NASA Astrophysics Data System (ADS)

Fluvial (i.e., riverine or river-like) channel patterns are prominently displayed on the subaerial surfaces of the terrestrial planets Venus, Earth and Mars. They also occur in submarine settings, as well as on the surfaces of the Moon and on Saturn's moon Titan. Some of these channel patterns seem clearly to derive from morphodynamical processes, i.e., processes involving the interaction and adjustment of the channel morphology to the entrainment, transport, and deposition of sediment. Other patterns, many with considerable resemblance to known morphodynamical ones, seem best explained by purely erosional processes or by construction that does not involve sedimentation (I.e., lava channels). While water is the best understood fluid in regard to causal association with many of these channels, other fluids with water-like properties are also involved. The latter include various lava compositions, particularly basaltic, and liquid methane (for Titan), both of which are capable to generating river-like channels. Indeed, for many extraterrestrial cases the formative fluid cannot be uniquely identified on the basis of the channel morphology alone. Instead, one must employ a search for consistency, coherence, and consilience among associated geological features in order to narrow the limits of possibility. The similarities in channel forms produced by these diverse fluid compositions and associated processes suggest that any general theory of fluvial channel patterns will have to encompass a much broader range of reality than what can be most commonly observed on Earth.

Baker, V. R.

2012-12-01

184

The impact of solar spectral irradiance variability on middle atmospheric ozone  

Microsoft Academic Search

This study presents the impact of solar spectral irradiance (SSI) variability on middle atmospheric ozone over the declining phase of solar cycle 23. Two different types of spectral forcing are applied to the Whole Atmosphere Community Climate Model (WACCM) to simulate the ozone response between periods of quiet and high solar activity. One scenario uses the solar proxy reconstructions model

Aimee W. Merkel; Jerald W. Harder; Daniel R. Marsh; Anne K. Smith; Juan M. Fontenla; Thomas N. Woods

2011-01-01

185

The Solar Bolometric Imager -A New Direction in Solar Irradiance Studies  

NASA Astrophysics Data System (ADS)

The Solar Bolometric Imager (SBI) is a novel solar imaging system with spectrally constant photometric response over all wavelengths between the UV and IR, which will provide a new tool for studying mechanisms of total irradiance variation. The SBI utilizes an 80,000 pixel, uncooled thermal IR imaging array whose spectral absorptance has been modified by CRI to provide uniform response over the wavelength range between at least 0.3 um and 2.5 um, containing 95% of the total solar irradiance. We have demonstrated that ferro-electric uncooled arrays can be modified to meet the SBI's spectral uniformity requirements with the deposition of gold blacks, and we have also identified two promising approaches for modifying the spectral absorptance of uncooled microbolometer arrays. A modified 8-bit Raytheon ferro-electric camera is being tested in the lab and on a telescope, while a 12-bit camera that will accommodate either ferro-electric or microbolometer arrays, is under development. The prototype SBI telescope utilizes a Dall-Kirkham design with uncoated (i.e. bare glass) primary and secondary mirrors in order to provide uniform spectral response and reduce the irradiance at the focal plane. Our present research focuses on image quality, photometric precision, stray light, and solar heating in this ground-based, prototype SBI. Ultimately, the SBI will be used to measure and remove temporal variations in solar irradiance due to photospheric magnetic structures, so that the importance of residual variations that may drive secular climate variations associated with global warming, can be determined. Much of the science potential of the SBI could be realized in a balloon experiment while the combination of the SBI and a cavity radiometer would constitute an excellent SMEX experiment to address a key challenge identified in the Sun-Earth Connection Roadmap issued by NASA/OSS. This work is supported by NASA research grant number NAG5-6979.

Libonate, S.; Foukal, P. V.

1999-05-01

186

Isotopic anomalies and proton irradiation in the early solar system  

NASA Technical Reports Server (NTRS)

Nuclear cross sections relevant to the various isotopic-abundance anomalies found in solar-system objects are evaluated in an attempt to set constraints on the hypothesized mechanism of irradiation of forming planetesimals by energetic protons from the young sun. A power-law proton spectrum is adopted, attention is restricted to proton energies less than about 20 MeV, and average cross sections are calculated for several reactions that might be expected to lead to the observed anomalies. The following specific anomalies are examined in detail: Al-26, Na-22, Xe-126, I-129, Kr-80, V-50, Nb-92, La-138, Ta-180, Hg-196, K-40, Ar-36, O-17, O-18, N-15, C-13, Li, Be, and B. It is suggested that the picture of presolar-grain carriers accounts for the facts more naturally than do irradiation models.

Clayton, D. D.; Dwek, E.; Woosley, S. E.

1977-01-01

187

Biological dosimetry of solar radiation for different simulated ozone column thicknesses.  

PubMed

During the Spacelab mission D-2, in the experiment RD-UVRAD, precalibrated biofilms consisting of dry monolayers of immobilised spores of Bacillus subtilis (strain Marburg) were exposed, for defined intervals, to extraterrestrial solar radiation filtered through an optical filtering system, to simulate different ozone column thicknesses. After the mission, the biofilms were processed and optical densities indicative of any biological activity were determined for each exposure condition by image analysis. For the different simulated ozone column thicknesses, biologically effective irradiances were experimentally determined from the biofilm data and compared with calculated data using a radiative transfer model and the known biofilm action spectrum. The data show a strong increase in biologically effective solar UV irradiance with decreasing (simulated) ozone concentrations. The full spectrum of extraterrestrial solar radiation leads to an increment of the biologically effective irradiance by nearly three orders of magnitude compared with the solar spectrum at the surface of the Earth for average total ozone columns. PMID:8622182

Horneck, G; Rettberg, P; Rabbow, E; Strauch, W; Seckmeyer, G; Facius, R; Reitz, G; Strauch, K; Schott, J U

1996-02-01

188

Preliminary low temperature electron irradiation of triple junction solar cells  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

189

Finding Extraterrestrial Organisms Living on Thermosynthesis  

NASA Astrophysics Data System (ADS)

During thermal cycling, organisms could live on thermosynthesis, a theoretical mechanism applicable to the origin of life and the early evolution of biological energy conversion. All extraterrestrial ice may be a repository for frozen dead or dormant organisms from earlier stages of evolution. In the presence of a thermal gradient within the ice, organisms might still be harvesting energy from thermosynthesis. Possible habitats for thermosynthesizers can be found throughout the Solar System, particularly in the cold traps on Mercury and the Moon, convecting waters on Mars, the oceans on moons in the outer Solar System, and smaller bodies rotating in the sunlight such as cosmic dust, meteorites, asteroids, and comets. A general strategy for detecting thermosynthetic organisms on Earth is offered, and highlights of current and upcoming robotic exploratory missions relevant to the detection of thermosynthesis are reviewed.

Muller, Anthonie W. J.

2003-11-01

190

Reconstruction of total and spectral solar irradiance in the satellite era  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

191

Solar total irradiance variability measurements by the SMM/ACRIM I experiment  

NASA Technical Reports Server (NTRS)

Convincing evidence of solar total irradiance variability and its relationships with solar activity was provided by the Active Cavity Radiometer Irradiance Monitor I (ACRIM I) experiment on the NASA Solar Maximum Mission (SMM). SMM/ACRIM I, the first flight experiment dedicated to the task of solar irradiance monitoring, has produced a multiyear solar total irradiance data base with + or - 0.02% or better long term precision since its launch in February, 1980. While the climatological significance of the results will not be apparent until many more years of continuous data are acquired, the discovery of variability on solar active region time scales has provided new insight into the physics of solar activity in the early years of the mission.

Willson, R. C.

1984-01-01

192

Solar irradiance and total ozone over El Arenosillo (Spain) during the solar eclipse of 3 October 2005  

NASA Astrophysics Data System (ADS)

The ground track of the annular eclipse of 3 October 2005 crossed the Iberian Peninsula. The main objective of this work was to analyze the variability of the solar irradiance and the total ozone column during the course of this event at El Arenosillo (Southwestern Spain). For achieving this goal, two Kipp Zonen broadband radiometers (one for measuring total solar irradiance and other for measuring ultraviolet erythemal solar irradiance), one NILU-UV multi-band instrument and one Brewer spectroradiometer were used in this work. Total irradiance (310-2800 nm), and ultraviolet erythemal radiation (UVER) were recorded at a high frequency of 5 s, showing a strong reduction (higher than 80%) of the irradiance at the maximum solar obscuration which was of 79.6%. The irradiance decrease during the course of the eclipse was positively correlated with the percentage of eclipse obscuration, showing a very high agreement (R2~0.99). The irradiance recorded at selected wavelengths from the NILU-UV instrument shows a more pronounced decrease in the UV irradiance at the lower wavelengths during the solar eclipse. Finally, the evolution of the total ozone column (TOC) derived from Brewer and NILU instruments during the eclipse presented an opposite behavior: while the Brewer derived TOC values increase about 15 DU, the NILU derived TOC values decrease about 11 DU. This opposite behavior is mainly related to an artifact in the spectral irradiances recorded by the two instruments.

Antón, M.; Serrano, A.; Cancillo, M. L.; Vaquero, J. M.; Vilaplana, J. M.

2010-06-01

193

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

194

Impact of simulated solar irradiation on disinfection byproduct precursors.  

PubMed

The Sacramento-San Joaquin Delta is the major drinking water source for 23 million California residents. Consequently, many studies have examined disinfection byproduct (DBP) formation in relation to Delta dissolved organic carbon (DOC) concentration. However, DOC characteristics within the Delta are not the same as those entering downstream water treatment facilities. As water is transferred to Southern California through the California Aqueduct, a 714.5 km-open channel, it is exposed to sunlight, potentially altering DBP precursors. We collected water from three sites within the Delta and one nearthe California Aqueduct, representing different DOC sources, and irradiated them in a solar simulator at a dose equivalent to that received during four days conveyance in the aqueduct. Photolytic changes in DOC were assessed by measuring CO2 and organic acid production, fluorescence, and ultraviolet absorbance over time. Trihalomethane (THM) and haloacetic acid (HAA) formation potentials, as well as the distribution of hydrophobic, transphilic, and hydrophilic acid fractions were determined at exposures equivalent to one and four days. Solar irradiation significantly decreased ultraviolet absorbance and fluorescence intensity, produced organic acids, and increased the hydrophilic fraction of waters. These changes in DOC caused a shift in bromine incorporation among the THM and HAA species. Our results are the first to demonstrate the importance of sunlight in altering DOC with respect to DBP formation. PMID:18754480

Chow, Alex T; Leech, Dina M; Boyer, Treavor H; Singer, Philip C

2008-08-01

195

Extraterrestrial Nucleobases in Carbonaceous Chondrites  

NASA Astrophysics Data System (ADS)

Nucleobases in Carbonaceous Chondrites Z. Martins (1), O. Botta (2), M. L. Fogel (3), M. A. Sephton (4), D. P. Glavin (2), J. S. Watson (5), J. P. Dworkin (2), A. W. Schwartz (6) and P. Ehrenfreund (1,6). (1) Astrobiology Laboratory, Leiden Institute of Chemistry, Leiden, The Netherlands, (2) NASA Goddard Space Flight Center, Goddard Center for Astrobiology, Greenbelt, MD, USA, (3) GL, Carnegie Institution of Washington, Washington DC, USA, (4) Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, South Kensington Campus, Imperial College, London, UK, (5) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes, UK, (6) Radboud University Nijmegen, Nijmegen, The Netherlands. E-mail: z.martins@chem.leidenuniv.nl/Phone:+31715274440 Nucleobases are crucial compounds in terrestrial biochemistry, because they are key components of DNA and RNA. Carbonaceous meteorites have been analyzed for nucleobases by different research groups [1-5]. However, significant quantitative and qualitative differences were observed, leading to the controversial about the origin of these nucleobases. In order to establish the origin of these compounds in carbonaceous chondrites and to assess the plausibility of their exogenous delivery to the early Earth, we have performed formic acid extraction of samples of the Murchison meteorite [6], followed by an extensive purification procedure, analysis and quantification by high-performance liquid chromatography with UV absorption detection and gas chromatography-mass spectrometry. Our results were qualitatively consistent with previous results [3, 4], but showed significant quantitative differences. Compound specific carbon isotope values were obtained, using gas chromatography-combustion- isotope ratio mass spectrometry. A soil sample collected in the proximity of the Murchison meteorite fall site was subjected to the same extraction, purification and analysis procedure. Our stable carbon isotope measurements clearly demonstrate that the nucleobases in the Murchison meteorite are indigenous to the meteorite, and clearly differ from the values determined for the terrestrial nucleobases measured in the soil collected at the impact site. These results support the hypothesis that nucleobases were exogenously delivered to the early Earth, and may have been important for the prebiotic chemistry on our young planet. With regard to the detection of traces of life on other planets such as Mars it is essential to characterize organic materials that have been exogenously delivered to the early planets. The analysis of the composition and isotopic fractionation of extraterrestrial material using complementary techniques can provide crucial insights into the formation of our Solar System, extraterrestrial delivery processes and subsequent addition and incorporation into the carbonaceous material available on the young planets. Ultimately, these parameters form an essential reference point for interpreting biosignatures that may be left in the ancient rock record on a planetary body. References: [1] Hayatsu R. et al. 1975. Geochimica et Cosmochimica Acta 39: 471- 488. [2] Folsome C. E. et al. 1971. Nature 232: 108-109. [3] Stoks P. G. & Schwartz A. W. 1979. Nature 282: 709-710. [4] Stoks P.G. & Schwartz A. W. 1981. Geochimica et Cosmochimica Acta 45: 563-569. [5] Shimoyama A. et al. 1990. Geochemical Journal 24: 343-348. [6] Martins Z. et al. 2004. Meteoritics & Planetary Science 39: A5145. 2

Martins, Z.; Botta, O.; Fogel, M.; Sephton, M.; Glavin, D.; Watson, J.; Dworkin, J.; Schwartz, A.; Ehrenfreund, P.

196

Extraterrestrial civilizations: Problems of their evolution  

NASA Technical Reports Server (NTRS)

The problem of finding extraterrestrial civilizations and establishing contact with them is directly related to the problem of their evolution. Possible patterns in this evolution and the stages in the evolution of extraterrestrial civilizations are examined.

Leskov, L. V.

1987-01-01

197

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

Microsoft Academic Search

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

Robert O. Green; Bo-Cai Gao

1993-01-01

198

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

NASA Technical Reports Server (NTRS)

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.

Green, Robert O.; Gao, Bo-Cai

1993-01-01

199

Prediction of the performance degradation of GaAs solar cells by electron irradiation  

Microsoft Academic Search

Solar cells exposed to irradiation undergo severe degradation in their performance due to induced structural defects. To predict this effect, the current-voltage characteristics under AM0 illumination for a constant dose of electron irradiation are numerically calculated. From these characteristics the solar cell output parameters: the short circuit current density Jsc, the open circuit voltage Voc, the fill factor FF and

A. F. Meftah; N Sengouga

2008-01-01

200

Airborne measurements of aerosol, ozone, and solar ultraviolet irradiance in the troposphere  

Microsoft Academic Search

Measurements of the distributions of the aerosol characteristics and solar ultraviolet irradiance were conducted by using instrumentation flown on a Falcon aircraft over the entire Greek area from the sea up to the middle troposphere. To study the impact of the aerosol abundance to the solar ultraviolet irradiance at various altitudes, complementary observations of ozone concentration, relative humidity, and temperature

Costas Varotsos

2005-01-01

201

Impact of cirrus crystal shape on solar spectral irradiance: A case study for subtropical cirrus  

Microsoft Academic Search

Profiles of in situ measurements of ice crystal size distribution of subtropical cirrus were used to calculate solar spectral irradiances above and below the clouds. Spheres and nonspherical ice crystal habits (columns, hollows, plates, bullets, and aggregates) were assumed in the calculations. The simulation results were compared to irradiance measurements from the NASA Solar Spectral Flux Radiometer. The microphysical and

Manfred Wendisch; Peter Pilewskie; John Pommier; Steve Howard; Ping Yang; Andrew J. Heymsfield; Carl G. Schmitt; Darrel Baumgardner; Bernhard Mayer

2005-01-01

202

Universalist ethics in extraterrestrial encounter  

NASA Astrophysics Data System (ADS)

If humanity encounters an extraterrestrial civilization, or if two extraterrestrial civilizations encounter each other, then the outcome may depend not only on the civilizations' relative strength to destroy each other but also on what ethics are held by one or both civilizations. This paper explores outcomes of encounter scenarios in which one or both civilizations hold a universalist ethical framework. Several outcomes are possible in such scenarios, ranging from one civilization destroying the other to both civilizations racing to be the first to commit suicide. Thus, attention to the ethics of both humanity and extraterrestrials is warranted in human planning for such an encounter. Additionally, the possibility of such an encounter raises profound questions for contemporary human ethics, even if such an encounter never occurs.

Baum, Seth D.

2010-02-01

203

New insights on short-term solar irradiance forecast for space weather applications  

NASA Astrophysics Data System (ADS)

The conditions of the thermosphere, the ionosphere, the neutral atmosphere, and the oceans on time scales from days to millennia are highly dependent on the solar electromagnetic output, the solar irradiance. The development of physics-based solar irradiance models during the last decade improved significantly our understanding of the solar forcing on Earth's climate. These models are based on the assumption that most of the solar irradiance variability is related to the magnetic field structure of the Sun. Recently, these models were extended to allow short-term forecast (1 to 15 days) of the total and spectral solar irradiance. The extension of the irradiance models is based on solar surface magnetic flux models and/or artificial neural network models. Here, we discuss in details the irradiance forecast models based on observations of the solar surface magnetic field realized by the HMI instrument on board of SDO spacecraft. We constrained and validated the models by comparing the output of the models and observations of the solar irradiance made by instruments onboard The SORCE spacecraft. This study received funding from the European Community's Seventh Framework Programme (FP7/2007-2013, FP7-SPACE-2010-1) under the grant agreement nrs. 218816 (SOTERIA project, www.soteria-space.eu) and 261948 (ATMOP,www.atmop.eu), and by the CNPq/Brazil under the grant number 312488/2012-2. We also gratefully thank the instrument teams for making their data available.

Vieira, L. A.; Dudok de Wit, T.; Balmaceda, L. A.; Dal Lago, A.; Da Silva, L. A.; Gonzalez, W. D.

2013-12-01

204

Near-term Forecasting of Solar Total and Direct Irradiance for Solar Energy Applications  

NASA Astrophysics Data System (ADS)

Integration of solar renewable energy into the power grid, like wind energy, is hindered by the variable nature of the solar resource. One challenge of the integration problem for shorter time periods is the phenomenon of "ramping events" where the electrical output of the solar power system increases or decreases significantly and rapidly over periods of minutes or less. Advance warning, of even just a few minutes, allows power system operators to compensate for the ramping. However, the ability for short-term prediction on such local "point" scales is beyond the abilities of typical model-based weather forecasting. Use of surface-based solar radiation measurements has been recognized as a likely solution for providing input for near-term (5 to 30 minute) forecasts of solar energy availability and variability. However, it must be noted that while fixed-orientation photovoltaic panel systems use the total (global) downwelling solar radiation, tracking photovoltaic and solar concentrator systems use only the direct normal component of the solar radiation. Thus even accurate near-term forecasts of total solar radiation will under many circumstances include inherent inaccuracies with respect to tracking systems due to lack of information of the direct component of the solar radiation. We will present examples and statistical analyses of solar radiation partitioning showing the differences in the behavior of the total/direct radiation with respect to the near-term forecast issue. We will present an overview of the possibility of using a network of unique new commercially available total/diffuse radiometers in conjunction with a near-real-time adaptation of the Shortwave Radiative Flux Analysis methodology (Long and Ackerman, 2000; Long et al., 2006). The results are used, in conjunction with persistence and tendency forecast techniques, to provide more accurate near-term forecasts of cloudiness, and both total and direct normal solar irradiance availability and variability. This new system could be a long term economical solution for solar energy applications.xample of SW Flux Analysis global hemispheric (light blue) and direct (yellow) clear-sky shortwave (SW) along with corresponding actual global hemispheric (blue) and direct (red) SW, and the corresponding fractional sky cover (black, right Y-axis). Note in afternoon about 40-50% of the global SW is available, yet most times there is no direct SW.

Long, C. N.; Riihimaki, L. D.; Berg, L. K.

2012-12-01

205

ACRIM3 and the Total Solar Irradiance database  

NASA Astrophysics Data System (ADS)

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 during this period than predicted by current climate models.

Willson, Richard C.

2014-05-01

206

Do Flares Contribute to Total Solar Irradiance Variability ?  

NASA Astrophysics Data System (ADS)

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)

Kretzschmar, M.; Dudok de Wit, T.

2010-12-01

207

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

SciTech Connect

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)

Martin, Luis; Marchante, Ruth; Cony, Marco [Investigaciones y Recursos Solares Avanzados (IrSOLaV), Tres Cantos 2 8045 (Spain); Zarzalejo, Luis F.; Polo, Jesus; Navarro, Ana [Energy Department, CIEMAT, Madrid 28040 (Spain)

2010-10-15

208

Spatial interpolation of solar irradiation data over complex orography: Solar map of Canaries Islands  

NASA Astrophysics Data System (ADS)

In this paper, we describe the calculation methodology we used to determine the spatial structure of solar irradiation over a very complex orography, such as the Canary archipelago, that is broken in seven islands, with only 7500 km2, and with heights in some of the islands upper than 1800 m, that reach to 3718 m in the case of Tenerife island. Starting with the method of Cumulative Semivariograms1, already used to face the irradiation spatial interpolation problem, although not for a complex orography. In this sense, some major modifications are introduced to deal with our needs, which can be summarized as: a) interpolation of clearness index data (Kcd, defined as the division of the global horizontal data, between the corresponding clear sky global horizontal values, obtained from a suitable model) instead of solar irradiation data; b) topographic considerations are included in the clear sky model, such as topographics shadows. This impacts directly over direct component of solar irradiation, and has a minor effect over the diffuse component, arising from a non plane visible horizon; c) the meteorological stations are selected by a criteria of weather proximity, instead of geographic proximity as it was proposed in the original methodology of Cumulative Semivariograms; d) the final result is obtained as the composition of various maps obtained from error minimization within a neighborhood of each available station, instead of using irradiation isolines. A preliminary result with data registered only by Canary Islands Institute of Technology's stations, spread over the whole archipelago, is showed. From our results we can see both, the power of the developed methodology and some limitations due to the extremely complex orography as it is the case of Canary Islands, which consists of a wide variety of microclimate regions. Whenever additional information is available, either in the form of empiric knowledge of the local weather, or in the form of other available radiometric data sources, the results do improve. In the case that all available stations are already used, the empirical knowledge of weather conditions can be introduced in our model by means of a strain parameter that modifies the statistical weight associated to the corresponding station in a given neighborhood. On the other hand, whenever it is possible to increase the spatial density of data sources, that is, to incorporate data from others stations, the result improves provided that data quality is good enough. To validate the results obtained with our methodology, we calculate the error between the estimated solar irradiation at the location of the stations with the records obtained by them.

Ortegón Gallego, A.

2010-09-01

209

Turbidity coefficients from normal direct solar irradiance in Central Spain  

NASA Astrophysics Data System (ADS)

Atmospheric turbidity causes attenuation of solar radiation reaching the earth's surface under a cloudless sky. The Ångström turbidity coefficient and the aerosol optical thickness, AOD550, were obtained from 10-minute direct normal solar irradiance measurements recorded in a rural area of Castilla y León region, Spain, from July 2010 to December 2012. During the study period, the diurnal variation of the mean monthly 10-minute turbidity coefficient increased in early morning, remained with fluctuations around noon, and increased or diminished in the evening, near sunset. The monthly turbidity coefficient shows an annual cycle with minimum values in winter and maximum values in summer, varying between 0.04 in winter and 0.16 in summer. The frequency distribution of 10-min Ångström turbidity coefficient on cloudless days shows that 0.65% of values are below 0.02, 84.50% between 0.02 and 0.15, and 14.85% above 0.15. Comparing at solar noon AOD550nm retrieved from MODIS (MODerate resolution Imaging Spectroradiometer on-board the Terra satellite) with those estimated from direct normal solar radiation measurements shows a good correlation coefficient of 0.78, although MODIS values are lower than estimated ones. High turbidity situations were investigated depending on the season and air-mass origin; the results show that they might be attributed to aerosol dust from the Sahara desert.The most significant high turbidity situations were investigated on base of wind at 700 mb and air-mass origin; the result shows that this might be attributed to aerosol dust from the Sahara desert.

Bilbao, J.; Román, R.; Miguel, A.

2014-06-01

210

Solar irradiance at the Earth's surface: long-term behavior observed at the South Pole  

Microsoft Academic Search

This research examines a 17-year database of UV-A (320-400 nm) and visible (400-600 nm) solar irradiance obtained by a scanning spectroradiometer located at the South Pole. The goal is to define the variability in solar irradiance reaching the polar surface, with emphasis on the influence of cloudiness and on identifying systematic trends and possible links to the solar cycle. To

J. E. Frederick; A. L. Hodge

2010-01-01

211

Solar irradiance at the earth's surface: long-term behavior observed at the South Pole  

Microsoft Academic Search

This research examines a 17-year database of UV-A (320-400 nm) and visible (400-600 nm) solar irradiance obtained by a scanning spectroradiometer located at the South Pole. The goal is to define the variability in solar irradiance reaching the polar surface, with emphasis on the influence of cloudiness and on identifying systematic trends and possible links to the solar cycle. To

J. E. Frederick; A. L. Hodge

2011-01-01

212

Extraterrestrial coastal geomorphology  

Microsoft Academic Search

Earth is the only planet in the solar system where large amounts of liquid water have been stable at the surface throughout geologic time. This unique trait has resulted in the production of characteristic landforms and massive accumulations of aqueous sediments, as well as enabled the evolution of advanced and diverse forms of life. But while Earth is the only

Timothy J. Parker; Donald R. Currey

2001-01-01

213

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

214

Short-term solar irradiance forecast for the efficiency assessment of photovoltaic systems in Poland  

Microsoft Academic Search

Efficiency of solar based energy generation systems depend to a large extent on weather conditions. In Poland, the solar irradiance is often highly variable due to passages of frontal zones and extratropical cyclones. Consequently, electricity generation varies in time and often energy production pattern does not follow load demand. Efficient management of a solar electricity production system requires reliable short-term

K. Sobotka; J. Struzewska; J. W. Kaminski

2010-01-01

215

Solar total irradiance variations and the global sea surface temperature record  

Microsoft Academic Search

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

George C. Reid

1991-01-01

216

Status of ISO-DIS 21348 for synthetic solar spectral irradiance models  

Microsoft Academic Search

We present the current methodology in place for our development and production use of synthetic models of the solar spectral irradiance (Fontenla et al. 1999, Fox et al. 2004). The goal of the synthesis is the successful combination of realistic representations of the observed solar disk with semi-empirical models and the theory for calculation of a mixed line+continuum solar spectrum

P. Fox

2004-01-01

217

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

Microsoft Academic Search

Knowledge of the top of the atmosphere (TOA) solar spectral irradiance (SSI) is crucial in interpreting the spectrally dependent radiative processes throughout Earth's climate system. Where this energy is deposited into the atmosphere and surface, how the climate responds to solar variability, and the mechanisms of climate response, are highly dependent on how the incident solar radiation is distributed with

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

2010-01-01

218

Variations of solar spectral irradiance from near UV to the infrared—measurements and results  

Microsoft Academic Search

Solar spectral irradiance variations are known to exhibit a strong wavelength dependence with the amount of variability increasing towards shorter wavelengths. The bulk of solar radiation is emitted at visible and infrared wavelengths. Thus, the spectral radiation length of 300nm accounts for 99% of the total solar radiative output. Deposited in the Earth's troposphere and biosphere, this part of the

M. Fligge; S. K. Solanki; J. M. Pap; C. Fröhlich; Ch. Wehrli

2001-01-01

219

The Search for Extraterrestrial Intelligence.  

ERIC Educational Resources Information Center

Traces the efforts of Searching for Extraterrestrial Technological Intelligence (SETI) since 1960 when a radio-telescope was used to see if any messages were being sent from the vicinity of two nearby stars. Describes attempts to detect microwave/optical signals and technological modification of the cosmic environment. (Author/KHR)

Jones, Barrie W.

2003-01-01

220

ExtraTerrestrial Radio Transmissions  

Microsoft Academic Search

WE are witness again to a surge of interest in, and speculation about, extra-terrestrial radio transmissions which had an earlier flare in the late twenties1. The favourable change in climate for the expression of such ideas since the turn of the century has been of particular interest to me. In 1899, Nikola Tesla established an experimental station at Colorado Springs,

Leland I. Anderson

1961-01-01

221

The Solar Irradiance Spectrum at Solar Activity Minimum Between Solar Cycles 23 and 24  

NASA Astrophysics Data System (ADS)

On 7 February 2008, the SOLAR payload was placed onboard the International Space Station. It is composed of three instruments, two spectrometers and a radiometer. The two spectrometers allow us to cover the 16 - 2900 nm spectral range. In this article, we first briefly present the instrumentation, its calibration and its performance in orbit. Second, the solar spectrum measured during the transition between Solar Cycles 23 to 24 at the time of the minimum is shown and compared with other data sets. Its accuracy is estimated as a function of wavelength and the solar atmosphere brightness-temperature is calculated and compared with those derived from two theoretical models.

Thuillier, G.; Bolsée, D.; Schmidtke, G.; Foujols, T.; Nikutowski, B.; Shapiro, A. I.; Brunner, R.; Weber, M.; Erhardt, C.; Hersé, M.; Gillotay, D.; Peetermans, W.; Decuyper, W.; Pereira, N.; Haberreiter, M.; Mandel, H.; Schmutz, W.

2014-06-01

222

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

NASA Astrophysics Data System (ADS)

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 the climate community, who will accompany their research work with wide dissemination activities.

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

223

Ethics and extraterrestrial life  

Microsoft Academic Search

\\u000a The study of other planets and moons in the Solar System has revealed the presence of environments that may be conducive to\\u000a life. The discovery of sulphate- bearing rocks on Mars,201 and the suggestion that they were formed in bodies of standing water,has invigorated the debate on the subject of the past,or\\u000a even present,existence of life on Mars. In parallel,the

Charles Cockell

224

Solar spectral irradiance and atmospheric transmission at Mauna Loa Observatory  

SciTech Connect

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.

Shaw, G.E.

1982-06-01

225

Solar spectral irradiance and atmospheric transmission at Mauna Loa Observatory.  

PubMed

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

Shaw, G E

1982-06-01

226

Observations of solar spectral irradiance change during cycle 22 from NOAA9 Solar Backscattered Ultraviolet Model 2 (SBUV\\/2)  

Microsoft Academic Search

The NOAA-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 the stratospheric profile and total column amount of ozone, using the directional albedo as the input to the ozone retrieval algorithm. Almost

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

2004-01-01

227

ISS-SOLAR: Total (TSI) and spectral (SSI) irradiance measurements  

NASA Astrophysics Data System (ADS)

The primary objective of the ISS-SOLAR mission on Columbus (to be launched in 2006) is the quasi-continuous measurement of the solar irradiance variability with highest possible accuracy. For this reason the total spectral range will be recorded simultaneously from 3000 to 17 nm by three sets of instruments: SOVIM is combining two types of absolute radiometers and three-channel filter radiometers. SOLSPEC is composed of three double monochromators using concave gratings, covering the wavelength range from 3000 to 180 nm. SOL-ACES has four grazing incidence planar grating spectrometers plus two three-signal ionization chambers (two signals from a two stage chamber plus a third signal from a silicon diode at the end of the chamber) with exchangeable band pass filters to determine the absolute fluxes from 220 to 17 nm repeatedly during the mission. For the TSI the relative standard uncertainty (RSU) to be achieved is of the order of 0.15% and for the SSI from 1% in the IR/Vis, 2% in the UV, 5% in the FUV up to 10% in the XUV spectral regions. The general requirements for the TSI and SSI measurements and their conceptual realization within this payload will be discussed with emphasis on instrumental realization and calibration aspects.

Schmidtke, G.; Fröhlich, C.; Thuillier, G.

228

ISS-SOLAR: Total (TSI) and Spectral (SSI) Irradiance Measurements  

NASA Astrophysics Data System (ADS)

Related to the climatic aspects in atmospheric science the primary objective of the ISS-SOLAR Mission on Columbus (to be launched in 2006) is the quasi-continuous measurement of the solar irradiance variation with highest possible accuracy. For this reason the total spectral range will be recorded simultaneously for the first time from 3000-16 nm by three sets of instruments: SOVIM(3) is combining two types of absolute radiometers and three-channel filterradiometers. SOLSPEC(2) is composed of three concave grating spectrometers with two monochromators, each, covering the wavelength range from 3000-180 nm. SOL-ACES(1) has four grazing incidence planar grating spectrometers plus two three-signal ionization chambers with exchangeable band pass filters to determine the absolute fluxes from 220-16 nm repeatedly during the mission. For the TSI the absolute accuracy to be achieved is of the order of 0.1 % and for the SSI from 1 % in the VIS, 2 % in the UV, 5 % in the FUV to 10 % in the XUV spectral regions. The general requirements for the TSI and SSI measurements and their conceptual realization within the payload will be discussed with emphasis on instrumental realization and calibration aspects.

Schmidtke, G.; Thuillier, G.; Fröhlich, C.

229

Relation of White Light Coronal Brightness to Total Solar Irradiance  

NASA Astrophysics Data System (ADS)

The Large Angle and Spectrometric Coronagraph (LASCO) has been regularly observing the white light solar corona since 1996. The measured brightness arises from photospheric sunlight scattered by free electrons or by dust particles. Normally the intensity of the photosphere is assumed to be constant. The high sensitivity and stability of the LASCO data enables a test of that assumption by correlating the observed total brightness to Total Solar Irradiance (TSI) data sets. The data sets used were SORCE (TIM and SIM), PMOD composite, the NRL TSI Model and its components. The correlation coefficient varied from 0.83 to 0.92 depending upon the data set. This high degree of correlation and stability of LASCO provides an excellent relative calibration of the various TSI sources, enabling them to be placed on the same relative scale. This could be useful as an independent calibration check in determining the success of performing corrections to a particular TSI data set. We acknowledge the support of NASA.

Howard, R.; Battams, K.; Dennison, H.

2013-12-01

230

Results from the First Year of SOLID - the First Comprehensive European Solar Irradiance Data Exploitation  

NASA Astrophysics Data System (ADS)

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. The major objective of SOLID is to analyze and merge the complete set of European irradiance data, complemented by archive data that include data from non-European missions. The reconstructed time series will be used to bridge gaps in time and wavelength coverage of the observational data. Here we report on the first results obtained during the first year of SOLID. This includes the improvement of data analysis and error estimate of the irradiance and proxy time series, as well as an improved modeling of the solar spectral irradiance. The product is tailored towards the needs of the user communities, which were also compiled during the first phase of the project. Acknowledgement: The authors acknowledge that the research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7 2012) under grant agreement no 313188 (SOLID: First European SOLar Irradiance Data Exploitation)).

Haberreiter, Margit; Ahmed, Omar; Cessateur, Gael; Dasi, Maria; Delouille, Veronique; Del Zanna, Guilio; Dudok de Wit, Thierry; Ermolli, Ilaria; Kretzschmar, Matthieu; Krivova, Natalie; Mason, Helen; Misos, Stergios; Qahwaji, Rami; Schmutz, Werner; Schoell, Micha; Solanki, Sami; Thuillier, Gerard; Tourpali, Klairie; Unruh, Yvonne; Weber, Mark

2014-05-01

231

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

NASA Technical Reports Server (NTRS)

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.

Timothy, J. G.

1983-01-01

232

A Fundamental Study on Spectrum Center Estimation of Solar Spectral Irradiation by the Statistical Pattern Recognition  

NASA Astrophysics Data System (ADS)

With a background of environmental problems and energy issues, it is expected that PV systems will be introduced rapidly and connected with power grids on a large scale in the future. For this reason, the concern to which PV power generation will affect supply and demand adjustment in electric power in the future arises and the technique of correctly grasping the PV power generation becomes increasingly important. The PV power generation depends on solar irradiance, temperature of a module and solar spectral irradiance. Solar spectral irradiance is distribution of the strength of the light for every wavelength. As the spectrum sensitivity of solar cell depends on kind of solar cell, it becomes important for exact grasp of PV power generation. Especially the preparation of solar spectral irradiance is, however, not easy because the observational instrument of solar spectral irradiance is expensive. With this background, in this paper, we propose a new method based on statistical pattern recognition for estimating the spectrum center which is representative index of solar spectral irradiance. Some numerical examples obtained by the proposed method are also presented.

Iijima, Aya; Suzuki, Kazumi; Wakao, Shinji; Kawasaki, Norihiro; Usami, Akira

233

Solar irradiance in clear atmosphere: study of parameterisations of change with altitude  

NASA Astrophysics Data System (ADS)

Parameterisation of changes of the solar irradiance at ground level with a specific variable (e.g. solar zenithal angle, aerosol optical depth, altitude, etc.) is often used in operational processes because it saves computational time. This paper deals with the modelling of the vertical profile of downwelling solar irradiance for the first two kilometres above ground in clear sky conditions. Two analytical parameterisations are evaluated for direct and global irradiance in spectral bands as well as for the total irradiance. These parameterisations reproduce the vertical profile with good accuracy for global spectral irradiance and are less accurate for direct component, especially in turbid atmosphere. A piecewise linear interpolation technique using irradiance values known at surface and 4 altitudes every 500 m performs better in any case.

Oumbe, A.; Blanc, Ph.; Gschwind, B.; Lefevre, M.; Qu, Z.; Schroedter-Homscheidt, M.; Wald, L.

2011-08-01

234

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

NASA Technical Reports Server (NTRS)

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.

Heath, D. F.

1972-01-01

235

Extraterrestrial Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

To understand the origin of the Solar system and the origin of Life itself is one of the longest standing goals of human thought. Our Sun and its planets have formed out of an interstellar cloud which collapsed due to gravitational forces, forming a disk shaped so-called protosolar nebula, with the young star in the centre. Such disk shaped and dust grain containing protosolar nebulae have been observed. One of them is surrounding the young star Beta pictoris [1, 2]. Silicates, carbon and metal grains, oxides and sulfides should have been present. One of the important elements with relatively high abundance is iron. It is believed that simple molecules, such as water (H2O), carbon monoxide (CO), and hydrocarbons, were formed in this protosolar nebula [3]. As we know very well, at least in one case - our own Solar system - a variety of different objects were formed: planets, asteroids, and comets. At least on one of these planets, the Earth, life has formed. Today comets are believed to be remnants of the protosolar nebula, and the Sun and the planets are processed bodies, whereas asteroids are supposed to be only partially processed. The process of birth and evolution of our Solar system can be investigated indirectly by studying all the different members of the planetary system by means of remote sensing and planetary robotic space missions. One of the key elements in the evolution of the Solar system, and life itself, is iron. The chemistry of iron is strongly coupled to the chemistry of abundant elements as hydrogen, oxygen, and carbon. For instance, the oxidation state of iron in surface rocks of the planets is an important aspect because according to theoretical studies, iron contained in a planetary body should be the more oxidized the farther away from the sun this body has formed. By studying the cosmic history of iron, we have the possibility of understanding the chemical evolution of matter and life itself. Here, Mössbauer spectroscopy is the obvious tool, because it is a unique method for determining the oxidation state of the element iron, the mineralogical composition of iron containing rocks and their weathering products, meteorites and small grains from solid bodies, directly. This contributes to the understanding of the history and evolution of the planetary surfaces, for instance, the Martian surface, and their atmospheres.

Klingelhöfer, Göstar

236

Photo-recovery of electron-irradiated GaAs solar cells  

Microsoft Academic Search

The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, independent of the coverslide coatings, are of particular importance in terms of the predictability of GaAs solar-array lifetime in space: ( 1) The GaAs\\/Ge solar cells

Andrew Meulenberg

1995-01-01

237

Dependence of global temperatures on atmospheric CO2 and solar irradiance  

PubMed Central

Changes in global average temperatures and of the seasonal cycle are strongly coupled to the concentration of atmospheric CO2. I estimate transfer functions from changes in atmospheric CO2 and from changes in solar irradiance to hemispheric temperatures that have been corrected for the effects of precession. They show that changes from CO2 over the last century are about three times larger than those from changes in solar irradiance. The increase in global average temperature during the last century is at least 20 times the SD of the residual temperature series left when the effects of CO2 and changes in solar irradiance are subtracted.

Thomson, David J.

1997-01-01

238

Status of the ISO Draft Standard for Determining Solar Irradiances (CD 21348)  

NASA Astrophysics Data System (ADS)

A draft international standard has been developed through ISO TC20/SC14/WG4 to specify all representations of solar irradiances. Because solar irradiance measurements and modeling are constantly evolving through improved instrumentation, measurement techniques, and modeling capabilities, the draft standard has been written as a process-based standard. This format is designed to encourage the ongoing developments in the area of solar irradiance determination. The draft standard covers all representations of solar irradiances and is applicable to measurements, reference spectra, empirical models, and physics-based models. The purpose of the standard is to provide a common specification for all solar irradiances for use by space systems materials and environment users. A solar irradiance product or specification would be compliant with the standard if four criteria are followed. First, solar irradiances are reported, at the minimum, in SI units of Watts per square meter corrected to 1 AU. Second, the method of determining irradiances would be documented for data collection, processing, archiving, validation, accuracy, precision, methodology, and algorithm information. Where applicable, a description of proxies and independent data sets used in the derivation of empirical models, including the rationale for proxy selection, and the mathematical formulation for numerical models would be provided. Third, a compliant data set or model would be published in an internationally-available peer review journal. Fourth, the compliant data set or model would be archived in a method consistent with current technology that ensures international accessibility. A draft of the solar irradiance standard is publicly available for comment at the web site http://www.SpaceWx.com/.

Tobiska, Wk; Nusinov, Aa

239

A Three Component Proxy Model for the Solar Far Ultraviolet Irradiance  

NASA Astrophysics Data System (ADS)

This dissertation presents a solar irradiance proxy model for the solar far ultraviolet (FUV) irradiance between 120 nm and 200 nm. The solar features which emit almost all of the solar UV irradiance below 200 nm can be classified into three primary components: quiet sun, active network, and plage. Parameterization of these three components is characterized by the following equation: F(Lambda,t) = Fq(Lambda) (1 - CN(Lambda) + CN(Lambda)XN(t) + CP(Lambda)XP(t)), where F(Lambda,t) is the predicted irradiance, Fq(Lambda) is the reference irradiance. The CN and CP are linear regression coefficients. The XN and XP are the active network and plage components of the NOAA Mg 2 core to wing ratio. The highly accurate solar FUV irradiance measurements from the UARS SOLSTICE are used as input to the model. Parameterization of these three components better represents the multivariant trends that are seen in two component proxy models and which can add uncertainties of 20% or more to a model. These trends include differences between the 27-day rotation variability and the solar cycle variability when comparing solar UV irradiance time series, and a hysterisis effect which is the result of a time lag between the time series of two solar UV irradiances or indices. The daily plage area, from 1992 through 1995, is extracted from solar Ca 2 K line spectroheliograms and is used to derive the active network and plage components of the solar FUV irradiance and the Mg 2 core to wing ratio. The plage area is derived from the spectroheliograms using characteristics such as intensity, size, and filling factor. This three component proxy model is available from 1985 through 1995 and it has uncertainties of 7% or less for the solar FUV irradiance. Solar physics results are also presented. It is found that the daily averaged intensity of the Ca 2 K line active network, and plage, remains essentially constant over the solar cycle. Also, the absolute values of the plage intensity, relative to the quiet sun intensity, have been derived with unprecedented accuracy for the Ca 2 K line, Mg 2 h and k line, and the FUV wavelengths.

Worden, John R.

1996-01-01

240

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

241

Extraterrestrial accretion and glacial cycles  

NASA Technical Reports Server (NTRS)

We propose that the approx. 100-k.y. cycle seen in terrestrial glaciation is due to changes in meteor flux that come from changes in the Earth's orbit. This model can explain a 70-k.y. 'anomalous' period in climate data and the apparent discrepancy between present extraterrestrial fluxes and those in oceanic sediments. It can be tested by measuring Ir densities in sediments and ice during glacials and interglacials.

Muller, R. A.

1994-01-01

242

Originism - Ethics and Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

How should we treat extraterrestrial life, if we ever find it, and does a different origin of life imply a different ethical status? The most likely source of an ethical difference, or `originism,' is the inability to find a coherent definition of `life,' required to assess moral relevance in the first place. Although from a normative point of view biochemical architecture, in itself, does not provide a reason for a difference, there are numerous positions that might encourage us to treat an independent origin of life differently to life that is related to life on Earth. For example, from an instrumental point of view it would provide an opportunity to study another biological data point; it will be a new source of information about the evolution of life, and thus it might be afforded special status. We might consider extraterrestrial life to be special as prudence against the possibility of its mistreatment through an erroneous moral assessment of its worth. Whether extraterrestrial life exists of an independent origin or not, this analysis ultimately can provide a useful device for considering how we should treat entities on Earth whose status as `living' organisms is disputed, specifically viruses.

Cockell, C. S.

243

Sun as a variable star: solar and stellar irradiance variations. Final report.  

National Technical Information Service (NTIS)

The main objective of this Colloquium was to review the most recent results on the observations, theoretical interpretations, and empirical and physical models of the variations observed in solar and stellar irradiances, as well as on Sun-climate connecti...

J. M. Pap

1994-01-01

244

Influence of atmospheric aerosols on solar spectral irradiance in an urban area  

NASA Astrophysics Data System (ADS)

Solar radiation reaching the earth's surface at different wavelengths has been extensively discussed during the last decades. Great emphasis has been placed on the potential increase in surface UV radiation due to the depletion of stratospheric ozone. The present study reports the variation of solar spectral irradiance and its relation with aerosols over a typical urban environment in India. Synchronous measurements of aerosol optical depth, UV irradiance, aerosol-particle size, black carbon (BC) concentration and solar irradiance have been carried out at the urban station of Hyderabad located in central India. Considerable reduction in the UV intensity has been observed during periods of high aerosol loading. A comparison of the erythemal UV (UVery) intensities on normal day with those of high aerosol loading suggested a ˜24% decrease in the UVery reaching the ground. Satellite observations showed forest fire occurrence over the region. PAR and diffuse-to-direct-beam ratio of solar irradiance showed marked differences under varying aerosol-loading conditions.

Badarinath, K. V. S.; Kharol, Shailesh Kumar; Kaskaoutis, D. G.; Kambezidis, H. D.

2007-04-01

245

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

246

Controlling The Quality of Solar Irradiation Data By Means of A Web Service  

NASA Astrophysics Data System (ADS)

The control of the quality of the irradiation data is often a prerequisite to the further processing of the data. Though data are usually controlled by meteorological offices, the sources are so numerous that the user often faces time-series of measurements containing questionable values. As customers of radiation data, we established our own procedures to screen time-series of measurements. Since this problem of quality control is of concern to many researchers and engineers and since it is often a lengthy and tedious task, we decided to make this screening procedure available to everyone as a web service. This service is the purpose of this paper. The objective is not to perform a precise and fine control, an objective out of reach without details on the site and instruments, but to perform a likelihood control of the data and to check their plausibility. This is achieved by comparing observations with some expectations based upon the extraterrestrial irradiation and a simulation of the irradiation for clear skies. This service is available to everyone on the Web site www.helioclim.net. It offers a very convenient mean to check time-series of irradiation: data are input in a HTML page by a copy and paste procedure and the return is also a HTML page that can be analyzed in details for the data flagged as suspicious.

Geiger, M.; Diabaté, L.; Ménard, L.; Wald, L.

247

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

Microsoft Academic Search

The opportunity to insert state-of-the-art solar irradiance measurements and calculations, with subtle perturbations, into a narrow spectral resolution radiative transfer model has recently been facilitated through release of MODTRAN-5 (MOD5). The new solar data are from: (1) SORCE satellite measurements of solar variability over solar rotation cycle, & (2) ultra-narrow calculation of a new solar source irradiance, extending over the

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

2006-01-01

248

Solar irradiance at the earth's surface: long-term behavior observed at the South Pole  

NASA Astrophysics Data System (ADS)

This research examines a 17-year database of UV-A (320-400 nm) and visible (400-600 nm) solar irradiance obtained by a scanning spectroradiometer located at the South Pole. The goal is to define the variability in solar irradiance reaching the polar surface, with emphasis on the influence of cloudiness and on identifying systematic trends and possible links to the solar cycle. To eliminate changes associated with the varying solar elevation, the analysis focuses on data averaged over 30-35 day periods centered on each year's austral summer solstice. The long-term average effect of South Polar clouds is a small attenuation, with the mean measured irradiances being about 5-6% less than the clear-sky values, although at any specific time clouds may reduce or enhance the signal that reaches the sensor. The instantaneous fractional attenuation or enhancement is wavelength dependent, where the percent deviation from the clear-sky irradiance at 400-600 nm is typically 2.5 times that at 320-340 nm. When averaged over the period near each year's summer solstice, significant correlations appear between irradiances at all wavelengths and the solar cycle as measured by the 10.7 cm solar radio flux. An approximate 1.8 ± 1.0% decrease in ground-level irradiance occurs from solar maximum to solar minimum for the wavelength band 320-400 nm. The corresponding decrease for 400-600 nm is 2.4 ± 1.9%. The best-estimate declines appear too large to originate in the sun. If the correlations have a geophysical origin, they suggest a small variation in atmospheric attenuation with the solar cycle over the period of observation, with the greatest attenuation occurring at solar minimum.

Frederick, J. E.; Hodge, A. L.

2011-02-01

249

Solar irradiance at the Earth's surface: long-term behavior observed at the South Pole  

NASA Astrophysics Data System (ADS)

This research examines a 17-year database of UV-A (320-400 nm) and visible (400-600 nm) solar irradiance obtained by a scanning spectroradiometer located at the South Pole. The goal is to define the variability in solar irradiance reaching the polar surface, with emphasis on the influence of cloudiness and on identifying systematic trends and possible links to the solar cycle. To eliminate changes associated with the varying solar elevation, the analysis focuses on data averaged over 30-35 day periods centered on each year's austral summer solstice. The long-term average effect of South Polar clouds is a small attenuation, with the mean measured irradiances being about 5-6% less than the clear-sky values, although at any specific time clouds may reduce or enhance the signal that reaches the sensor. The instantaneous fractional attenuation or enhancement is wavelength dependent, where the percent deviation from the clear-sky irradiance at 400-600 nm is typically 2.5 times that at 320-340 nm. When averaged over the period near each year's summer solstice, significant correlations appear between irradiances at all wavelengths and the solar cycle as measured by the 10.7 cm solar radio flux. An approximate 1.8 ± 1.0% decrease in ground-level irradiance occurs from solar maximum to solar minimum for the wavelength band 320-400 nm. The corresponding decrease for 400-600 nm is 2.4 ± 1.9%. The best-estimate declines appear too large to originate in the sun. If the correlations have a geophysical origin, they suggest a small variation in atmospheric attenuation with the solar cycle over the period of observation, with the greatest attenuation occurring at solar minimum.

Frederick, J. E.; Hodge, A. L.

2010-11-01

250

Compact Flyeye concentrator with improved irradiance uniformity on solar cell  

NASA Astrophysics Data System (ADS)

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.

Zhuang, Zhenfeng; Yu, Feihong

2013-08-01

251

The moral status of extraterrestrial life.  

PubMed

If we eventually discover extraterrestrial life, do we have any moral obligations for how to treat the life-forms we find; does it matter whether they are intelligent, sentient, or just microbial-and does it matter that they are extraterrestrial? In this paper, I examine these questions by looking at two of the basic questions in moral philosophy: What does it take to be a moral object? and What has value of what kind? I will start with the first of these questions by looking at the most important attempts to answer this question on our own planet and by asking whether and how they could be applied to extraterrestrial life. The results range from a very strong protection of all extraterrestrial life and all extraterrestrial environments, whether inhabited or not, to total exclusion of extraterrestrial life. Subsequently, I also examine whether extraterrestrial life that lacks moral status can have value to human or alien life with moral status, and if that could generate any obligations for how to treat extraterrestrial life. Based on this analysis, I conclude that extraterrestrial life-forms can have both instrumental value and end value to moral objects, which has strong implications for how to treat them. PMID:23013271

Persson, Erik

2012-10-01

252

Interpretation of Solar Irradiance Monitor Measurements through Analysis of 3D MHD Simulations  

NASA Astrophysics Data System (ADS)

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.

Criscuoli, S.; Uitenbroek, H.

2014-06-01

253

Solar spectral irradiance variation and its impact on earth's atmosphere as observed by SCIAMACHY  

NASA Astrophysics Data System (ADS)

SCIAMACHY is a UV/vis/NIR spectrometer aboard ENVISAT which provides routine observations of ozone and other trace gases in the earth's atmosphere since 2002. Ozone profile data are provided from limb, lunar, and solar occultation observations, while the nadir viewing geometry allows measurements of total ozone columns. For normalizing observed backscattered earth radiances for trace gas retrievals, daily measurements of solar irradiance at moderately high spectral resolution (<1.5 nm) from 230 nm to 2400 nm, with some gaps in the NIR, are made. From the solar observations a Mg II index can be derived that in combination with other satellite data becomes a useful solar UV activity proxy indicator during the satellite era (since 1978). Using solar proxies for faculae brightening and sunspot darkening fitted to SCIAMACHY irradiance time-series a SCIA proxy model has been derived that allows us to describe solar cycle irradiance changes covering several decades. This talk will present highlights from SCIAMACHY solar observations, comparisons with other satellite data, and presents results on solar influence on ozone, i. e. 27 day solar rotation signal in the upper stratosphere and solar cycle effects on polar ozone losses.

Weber, M.; Pagaran, J.; Burrows, J. P.; Dikty, S.; von Savigny, C.; DeLand, M. T.; Floyd, L. E.; Harder, J. W.; Langematz, U.

2011-12-01

254

Effect of Electron Irradiation in Vacuum on Fep-a Silicon Solar Cell Covers.  

National Technical Information Service (NTIS)

Fluorinated ethylene-propylene-A (FEP-A) covers on silicon solar cells were irradiated with 1-MeV electrons, in vacuum, to an accumulated fluence equivalent to approximately 28 years in synchronous orbit. The effect of irradiation on the light transmittan...

S. J. Marsik J. D. Broder

1975-01-01

255

Irradiation and Measurements of Fluorinated Ethylene-Propylene-a on Silicon Solar Cells in Vacuum.  

National Technical Information Service (NTIS)

Silicon monoxide (SiO) coated silicon solar cells covered with fluorinated ethylene-propylene-A (FEP-A) were irradiated by 1-MeV electrons in vacuum. The effect of irradiation on the light transmittance of FEP-A was checked by measuring the short-circuit ...

J. D. Broder S. J. Marsik

1975-01-01

256

Degradation of tetracycline by photo-Fenton process—Solar irradiation and matrix effects  

Microsoft Academic Search

The degradation of the antibiotic tetracycline (TC) by the photo-Fenton process was evaluated under black-light and solar irradiation. The influences of iron source (Fe(NO3)3 or ferrioxalate), hydrogen peroxide and matrix (pure water, surface water and a sewage treatment plant effluent—STP) were evaluated. Under black-light irradiation, TC degradation was favored in the presence of Fe(NO3)3, achieving total degradation after 1min irradiation,

Ivonete Rossi Bautitz; Raquel F. Pupo Nogueira

2007-01-01

257

Solar magnetic field and irradiance: how unusual is the current minimum? (Invited)  

NASA Astrophysics Data System (ADS)

In many respects the current minimum of solar activity is rather different from other minima during the last half century, which has seen the Sun in a state of unusually high activity. This uncommon minimum has fascinated solar physicists. Of particular importance for our understanding is the behaviour of the magnetic field, which is the source of all activity observed in the solar atmosphere, including the heliosphere. Furthermore, the evolution of dark and bright magnetic features on the solar surface modulates the solar irradiance, which could directly influence the Earth's climate. In this presentation observations and models of the evolution of the Sun's magnetic field and irradiance are reviewed. After discussing the variation of these quantities over the solar cycle and from cycle to cycle, the current minimum is considered in greater detail. It is compared to earlier minima going back to the Maunder minimum and, in a more averaged sense, to solar activity and irradiance during the whole Holocene. Questions that will be considered are: Are we leaving the period of high solar activity (a grand maximum) to enter into a phase of more moderate activity, or even into a grand minimum? How could such a change in the level of the magnetic field and irradiance aid us in gaining further insight into the nature of the Sun's influence on the Earth's climate?

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

2009-12-01

258

Status of the ISO draft standard for determining solar irradiances (WD 21348)  

NASA Astrophysics Data System (ADS)

A draft international standard is being developed through ISO TC20/SC14/WG4 to specify all representations of solar irradiances. Because the discipline area of solar irradiance measurements and modeling is dramatically evolving through improved instrumentation, measurement techniques, and modeling capabilities, the draft standard is proposed as a process-based standard. This format is designed to encourage the ongoing developments in the field. The draft standard covers all representations of solar irradiances and is applicable to measurements, reference spectra, empirical models, and first-principles models. The purpose of the standard is to provide a common specification for all solar irradiances for use by space systems materials and environment users. A solar irradiance specification would be compliant with the standard if four criteria are followed. First, solar irradiances would be reported, at the minimum, in SI units of Watts per square meter corrected to 1 AU. Second, the method of determining irradiances would be documented for data collection, processing, archiving, validation, accuracy, precision, methodology, and algo-rithm information. Where applicable, a description of proxies and independent data sets used in the derivation of empirical models, including the rationale for proxy selection, and the mathematical formulation for numerical models would be provided. Third, a compliant data set or model would be published in an internationally- available peer review journal. Fourth, the compliant data set or model would be archived in a method consistent with current technology that ensures international accessibility. A draft of the solar irradiance standard is publicly available for comment at the web site http://SpaceWx.com/.

Tobiska, W.; Nusinov, A.

259

The Development of Politics in Extraterrestrial Colonies  

NASA Astrophysics Data System (ADS)

The existence of feudal or totalitarian interplanetary empires has been a favourite theme in Science Fiction. Although the vast distances between the stars make the emergence of an interstellar empire impossible without the creation of a faster than light drive, this is not necessarily true for the other worlds within our solar system. Environmental constraints on the off-world colonies themselves, and repressive, hierarchical and feudalistic social and commercial institutions and customs inherited from the parent cultures on Earth and a tradition of military rule descending from the foundation of these colonies may all work to bring about a new feudal or totalitarian social order on humanity's extraterrestrial colonies. There are encouraging signs that this may not be the case, however. Already the debate over the projected colonisation of Mars is a factor influencing present controversies over repressive institutions and customs. Nevertheless, those wishing for a free, democratic, and politically, socially and technologically innovative and vigorous human society spreading throughout the solar system should not become complacent.

Sivier, D. J.

260

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

261

Total Solar Irradiance Composites and the empirical analysis of the solar contribution to global mean air surface temperature change (Invited)  

NASA Astrophysics Data System (ADS)

We discuss the Total Solar Irradiance satellite composites and show that the ACRIM/PMOD controversy is still open to further investigation. In particular we show that TSI proxy models based on solar surface magnetic field disprove the alterations made by PMOD of the Nimbus record during the ACRIM gap (1989-1992). This suggest that the TSI may have increased from 1980 to 2000 as ACRIM science team has proposed. By using alternative TSI model we evaluate the solar contribution to global mean air surface temperature change by using an empirical bi-scale climate model characterized by both fast and slow characteristic time responses to solar forcing: T1 = 0.4 +/- 0.1 yr, and T2 = 8 +/- 2 yr or T2 = 12 +/- 3 yr. Since 1980 the solar contribution to climate change is uncertain because of the severe uncertainty of the total solar irradiance satellite composites. The sun may have caused from a slight cooling, if PMOD TSI composite is used, to a significant warming (up to 65% of the total observed warming) if ACRIM, or other TSI composites are used. The model is calibrated only on the empirical 11-year solar cycle signature on the instrumental global surface temperature since 1980. The model reconstructs the major temperature patterns covering 400 years of solar induced temperature changes, as shown in recent paleoclimate global temperature records.

Scafetta, N.

2009-12-01

262

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)

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.

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

1974-01-01

263

Application of Solar Spectral Irradiance Variability in a Earth Atmospheric Model  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

264

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

265

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

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

266

Solar UV Irradiances and Associated Issues for the Atmosphere and Ionosphere  

NASA Astrophysics Data System (ADS)

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.

Tobiska, W.

267

Extraterrestrial consumables production and utilization  

NASA Technical Reports Server (NTRS)

Potential oxygen requirements for lunar-surface, lunar-orbit, and planetary missions are presented with emphasis on: (1) emergency survival of the crew, (2) provision of energy consumables for vehicles, and (3) nondependency on an earth supply of oxygen. Although many extraterrestrial resource processes are analytically feasible, this study has considered hydrogen and fluorine processing concepts to obtain oxygen or water (or both). The results are quite encouraging and are extrapolatable to other processes. Preliminary mission planning and sequencing analysis has enabled the programmatic evaluation of using lunar-derived oxygen relative to transportation cost as a function of vehicle delivery and operational capability.

Sanders, A. P.

1972-01-01

268

Extraterrestrial intelligence: an observational approach.  

PubMed

The microwave region of the electromagnetic spectrum, a plausible regime for signals from extraterrestrial intelligences, is largely unexplored. With new technology, particularly in data processing and low-noise reception, surveys can be conducted over broad regions of frequency and space with existing antennas at flux densities plausible for interstellar signals. An all-sky, broad-band survey lasting perhaps 5 years can be structured so that even negative results would establish significant boundaries on the regime in which such signals may be found. The technology and techniques developed and much of the data acquired would be applicable to radio astronomy and deep-space communications. PMID:17749999

Murray, B; Gulkis, S; Edelson, R E

1978-02-01

269

An empirical model of total solar irradiance variation between 1874 and 1988.  

PubMed

An empirical model of variations in the total solar irradiance caused by observed changes in photospheric magnetic activity between 1874 and 1988 is presented. The model provides a remarkably good representation of the irradiance variations observed by satellite-borne radiometers between 1980 and 1988. It suggests that the mean total irradiance has been rising steadily since about 1945, with the largest peak so far at about 1980 and another large peak expected during the current solar cycle 22. But it is doubtful whether even this rise can contribute significantly to global warming, unless the temperature increase of about 0.02 degrees C that it produces in current energy balance models seriously underestimates the sensitivity of climate to solar irradiance changes. PMID:17743991

Foukal, P; Lean, J

1990-02-01

270

New Insights into Solar EUV Spectral Irradiance Variability from SDO-EVE  

NASA Astrophysics Data System (ADS)

The Extreme ultraviolet (EUV) Variability Experiment (EVE) on NASA's Solar Dynamics Observatory (SDO) satellite measures the solar spectral irradiance in the EUV at high temporal and spectral resolution. The Multiple EUV Grating Spectrographs (MEGS) on EVE make 0.1 nm spectral measurements with a 10-second cadence while the EUV Spectro-Photometer (ESP) makes broadband (~ 4 nm) measurements of select bands at 0.25-second cadence. Normal operations for EVE began May 1, 2010 at low solar conditions. Since then EVE has observed the EUV spectral irradiance changes during several hundred flares ranging from A to X class, in addition to the spectral variations from active region evolution and the rise from solar minimum conditions. These EUV spectral irradiance changes will be described, as will potential impacts to understanding the impacts on the thermosphere and ionosphere.

Eparvier, F. G.

2011-12-01

271

Proton and electron irradiation of MOCVD InP solar cells - Experimental results and radiation modelling  

NASA Astrophysics Data System (ADS)

One-MeV electron and 10-MeV proton irradiation of high-efficiency InP solar cells grown by metalorganic chemical vapor deposition (MOCVD) is reported. The MOCVD InP cells are shown to be more radiation resistant than Si and GaAs cells, especially at high fluences. Deep-level transient spectroscopy (DLTS) measurements on the InP solar cells are reported. The defect behavior is compared with cell parameters following irradiation and subsequent annealing stages. The correlation between changes in the solar cell output and the majority carrier (hole) DLTS spectrum reported in irradiated diffused junction InP was not observed in MOCVD InP. An approach to correlating electron- and proton-induced damage in InP solar cells based on calculations of the nonionizing energy loss (NIEL) is described.

Walters, R. J.; Messenger, S. R.; Summers, G. P.; Burke, E. A.; Keavney, C. J.

272

Response of the Bering Sea to 11-year solar irradiance cycles during the Bølling-Allerød  

NASA Astrophysics Data System (ADS)

studies find decadal climate variability possibly related to solar activity, although the details regarding the feedback with the ocean environment and ecosystem remain unknown. Here, we explore the feedback system of solar irradiance change during the Bølling-Allerød period, based on laminated sediments in the northern Bering Sea. During this period, well-ventilated water was restricted to the upper intermediate layer, and oxygen-poor lower intermediate water preserved the laminated sediment. An 11-year cycle of diatom and radiolarian flux peaks was identified from the laminated interval. Increased fresh meltwater input and early sea-ice retreat in spring under the solar irradiance maximum follow the positive phase of Arctic Oscillation which impacted the primary production and volume of upper intermediate water production in the following winter. Strength of this 11 year solar irradiance effect might be further regulated by the pressure patterns of Pacific decadal oscillation and/or El Niño-Southern Oscillation variability.

Katsuki, Kota; Itaki, Takuya; Khim, Boo-Keun; Uchida, Masao; Tada, Ryuji

2014-04-01

273

A I-V analysis of irradiated Gallium Arsenide solar cells  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

274

Researches of the Electrotechnical Laboratory, No. 830: Measurement of the Solar Spectral Irradiance at Tanashi, Tokyo (Iii).  

National Technical Information Service (NTIS)

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 ...

M. Habu M. Suzuki T. Nagasaka

1983-01-01

275

Total solar irradiance variations: The construction of a composite and its comparison with models  

NASA Technical Reports Server (NTRS)

Measurements of the total solar irradiance (TSI) during the last 18 years from spacecraft are reviewed. Corrections are determined for the early measurements made by the HF radiometer within the ERB experiment on NIMBUS 7 and the factor to refer active cavity radiometer irradiation monitoring (ACRIM) 2 to the ACRIM 1 irradiance scale. With these corrections, a composite TSI is constructed with a model that combines a magnetic brightness proxy with observed sunspot darkening and explains nearly 90 percent of the observed short and long term variance. Possible, but still unverified degradation of the radiometers hampers conclusions about irradiance changes on decadal time scales and longer.

Froehlich, Claus; Lean, Judith

1997-01-01

276

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

SciTech Connect

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.

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

1992-12-01

277

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

SciTech Connect

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.

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

1992-01-01

278

Solar Spectral Irradiance Variability in the Visible and Infrared During the SORCE Mission  

NASA Astrophysics Data System (ADS)

The Spectral Irradiance Monitor (SIM) is a dual prism spectrometer onboard the SORCE (Solar Irradiance and Climate Experiment) satellite that was launched in January 2003. SIM covers the wavelength region 200- 2700 nm with a spectral resolution varying from 0.25 to 34 nm over this range. The primary detector for this instrument is an electrical substitution radiometer (ESR), and three additional photodiode detectors complement the ESR measurement and span the spectral range from 308 to 1600 nm; these photodiodes provide the bulk of the data used to study solar variability. The ESR calibrates the radiant sensitivities of the photodiodes in flight, and pre-flight measurements of the prism transmission and the spectral response function give the absolute calibration of the instrument. The SIM solar spectrum is in good agreement with other standard solar spectra such as the SOLSPEC spectrum (Thuillier et al. Metrologia, 35, 689, 1998) and the Davos World Radiation Center Reference Spectrum (Wehrli, C., World Radiation Center (WRC) Publication No. 615, Davos-Dorf, Switzerland, July 1985). SIM is able to detect short-term spectral irradiance variability of about 0.1% in the of 27-day solar rotation period induced by the appearance and varying intensity of solar structural features (such as sun spots and plage) relative to the quiet sun. A comparative study of the SIM solar spectrum relative to other standard spectra and an analysis of short-term solar variability as measured by SIM will be presented.

Harder, J. W.; Fontenla, J.; Smiley, B.; Rottman, G.; Lawrence, G.; Woods, T.

2003-12-01

279

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)

Satellite observations of the sun over almost five years have shown that principally two UV active longitudes have persisted over a significant portion. A comparison between the position of solar magnetic sector boundaries and UV enhancements of the sun indicates that the UV maxima tend to occur near the times when a solar sector boundary is near central meridian. An estimate of the magnitude of the variable UV solar energy input into the atmosphere resulting from the rotation of active solar longitudes is that for wavelengths less than 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 UV irradiance from 120 to 300 nm over a solar rotation is typically at least 230 ergs/sq cms.

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

1974-01-01

280

Solar UV Spectral Irradiance Measurements at 0.15 nm Resolution by SUSIM  

NASA Astrophysics Data System (ADS)

The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) measured the solar UV spectral irradiance (115-410 nm) during the 14-year period, 1991-2005. Absolutely calibrated irradiances are produced at three wavelength resolutions, 5 nm (low), 1.1 nm (mid), and 0.15 nm (high). The changing wavelength- dependent responsivity of the SUSIM optical path is maintained throughout the mission through separate measurements of 4 stable deuterium lamps and solar measurements less frequently exposed optical elements comprising alternate optical paths. The high resolution spectra were gathered at weekly cadence early in mission and and monthly or lower cadence later on, subject to spacecraft resources and scheduling constraints. Approximately 400 of these SUSIM high resolution spectra are available throughout the operational period. Data reduction work continues on these spectra including recent improvements in their wavelength scales. Of particular interest is the value of these spectra in the development of solar radiance models because the resolved spectral features are more closely associated with specific solar atmospheric temperatures. One such model (Morrill, 2011) produces UV irradiances from the extremely high resolution spectral radiance measurements from HRTS, Mt. Wilson CaII K images, sunspot size and position records, as well as the SUSIM high resolution irradiances.

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

2011-12-01

281

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

NASA Astrophysics Data System (ADS)

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 readiness 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 SIM sensors, and plans to provide for traceability of total and spectral irradiance measurements to ground-based cryogenic standards.

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

2012-04-01

282

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

283

Impact of Cirrus Crystal Shape on Solar Spectral Irradiance: A Case Study for Subtropical Cirrus  

NASA Technical Reports Server (NTRS)

Profiles of in situ measurements of ice crystal size distribution of subtropical cirrus were used to calculate solar spectral irradiances above and below the clouds. Spheres and nonspherical ice crystal habits (columns, hollows, plates, bullets, and aggregates) were assumed in the calculations. The simulation results were compared to irradiance measurements from the NASA Solar Spectral Flux Radiometer. The microphysical and radiation data were collected by three aircraft during CRYSTAL-FACE. Two cirrus cases (optical thickness of about 1 and 7) from two mission dates (26 and 23 July 2002) were investigated in detail. The measured downwelling and upwelling irradiance spectra above the cirrus could mostly be reproduced by the radiation model to within +/- 5-10% for most ice crystal habits. Below the cirrus the simulations disagreed with the measured irradiances due to surface albedo variability along the flight track, and nonoptimal colocation between the microphysical and irradiance measurements. The impact of shape characteristics of the crystals was important for the reflected irradiances above the optically thin cirrus, especially for small solar zenith angles, because in this case single-scattering dominated the solar radiation field. For the cirrus of moderate optical thickness the enhanced multiple scattering tended to diminish particular shape features caused by nonspherical single-scattering. Within the ice absorption bands the shape-related differences in the absorption characteristics of the individual nonspherical ice crystals were amplified if multiple scattering prevailed. Furthermore, it was found that below the cloud the shape sensitivity of the downwelling irradiance spectra is larger compared to the nonsphericity effects on reflected irradiances above the cirrus. Finally, it was shown that the calculated cirrus solar radiative forcing could vary by as much as 26% depending on the ice crystal habit.

Wendisch, Manfred; Pilewskie, Peter; Pommier, John; Howard, Steve; Yang, Ping; Heymsfield, Andrew J.; Schmitt, Carl G.; Baumgardner, Darrel; Mayer, Barnhard

2005-01-01

284

Wavelength Dependence of Solar Flare Irradiation and its Influence on the Thermosphere  

NASA Technical Reports Server (NTRS)

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.

Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Qian, L.; Solomon, S.; Chamberlin, P.

2012-01-01

285

The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements  

NASA Astrophysics Data System (ADS)

Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3, and NO2), the measured solar spectra are compared with previous observations. Our solar irradiance is +1.6% larger than the re-calibrated Kurucz et al. (1984) solar spectrum (Fontenla et al., 1999, called MODTRAN 3.5) in the visible spectral range (435-650 nm), +1.5% larger in the (370-415 nm) wavelength interval, but -4% smaller in the UV spectral range (316.7-370 nm), when the Kurucz spectrum is convolved to the spectral resolution of our instrument. The same comparison with the SOLSPEC solar spectrum (Thuillier et al., 1997, 1998a, b) confirms the somewhat larger solar irradiance (+1.7%) measured by the balloon instrument from 435-500 nm, but not from 500-650 nm, where the SOLSPEC is -1.3% lower than MODTRAN 3.5. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen -) with MODTRAN 3.5 indicates an agreement of +0.2% in the visible spectral range (435-585 nm). With this calibration, the SCIAMACHY solar spectrum is congruent with the balloon observations (-1%) in the 316.7-370 nm wavelength range, but both are up to -5%/-3% smaller than MODTRAN 3.5 and SOLSPEC, respectively. In agreement with findings of Skupin et al. (2002) our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

Gurlit, W.; Bösch, H.; Bovensmann, H.; Burrows, J. P.; Butz, A.; Camy-Peyret, C.; Dorf, M.; Gerilowski, K.; Lindner, A.; Noël, S.; Platt, U.; Weidner, F.; Pfeilsticker, K.

2004-12-01

286

Solar Extreme Ultraviolet and X-ray Irradiance Measurements for Thermosphere and Ionosphere Studies (Invited)  

NASA Astrophysics Data System (ADS)

The solar extreme ultraviolet (EUV: 10-120 nm) and soft X-ray (SXR: 0.1-10 nm) radiation is critical energy input for Earth's upper atmosphere above 80 km as a driver for photochemistry, ionosphere creation, temperature structure, and dynamics. Understanding the solar EUV and X-ray variations and their influences on Earth's atmosphere are important for myriad of space weather applications. The solar EUV and SXR spectral irradiances are currently being measured by NASA's Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) Solar EUV Experiment (SEE), NASA's Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE), and NOAA's GOES X-Ray Sensor (XRS) and EUV Sensor (EUVS). The solar irradiance varies on all time scales, ranging from seconds to hours from solar flare events, to days from 27-day solar rotation, and to years and longer from 11-year solar cycle. The amount of variation is strongly wavelength dependent with smaller ~50% solar cycle variations seen in the EUV for transition region emissions and larger factor of 10 and more variations seen in the SXR for coronal emissions. These solar irradiance observations are expected to be continued and to overlap with NASA's future Global-scale Observations of the Limb and Disk (GOLD) and Ionospheric Connection (ICON) missions that focus on the study of the thermosphere and ionosphere. These current measurements are only broad band in the SXR, but there are plans to have new spectral SXR measurements from CubeSat missions that may also overlap with the GOLD and ICON missions.

Woods, T. N.; Caspi, A.; Chamberlin, P. C.; Eparvier, F. G.; Jones, A. R.; Sojka, J. J.; Solomon, S. C.; Viereck, R. A.

2013-12-01

287

Solar Flare Soft X-ray Irradiance and its Impact on the Earth's Upper Atmosphere  

NASA Astrophysics Data System (ADS)

Solar flare soft X-ray irradiance provides a highly variable energy source to the lower thermosphere. Observations from three NASA satellite missions, the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics - Solar Extreme Ultraviolet Experiment (TIMED-SEE), the Solar Radiation and Climate Experiment (SORCE) and the Student Nitric Oxide Explorer (SNOE) are analyzed to determine how solar soft X-ray irradiance varies during a solar flare and how this irradiance affects the Earth's lower thermosphere. Solar soft X-rays are one of the principal energy sources that lead to the production of thermospheric nitric oxide (NO) through the dissociation of odd-nitrogen. NO is an important source of radiative cooling in the thermosphere and therefore performs an important role in the energy balance. The XUV Photometer System (XPS) aboard TIMED-SEE and the XPS aboard SORCE both include a suite of photodiode detectors that measure the solar soft X-ray irradiance in broadband channels from 0.1 to 27 nm. The TIMED-SEE XPS observed 29 flares of various strengths over a six month period in 2002 and the SORCE XPS observed several large flares during the fall of 2003. An emission measure technique is used to interpret the broadband observations and determine a solar flare spectrum with a model that calculates theoretical spectra for input differential emission measures (DEM). The DEMs are iterated until the resulting spectrum reproduces the XPS observations. These solar flare spectra are used to determine the soft X-ray energy input to the Earth's lower thermosphere. Most of the solar flare soft X-ray irradiance comes from the 1 - 2 nm range and is deposited near 106 km. The abundance of NO peaks near 106 km and responds dramatically to energy deposited in the upper atmosphere. SNOE observed a significant increase in thermospheric NO following the X17 solar flare on 28 October 2003. Analysis of solar flare NO density enhancements and a comparison to results from a photochemical model will be presented along with a description of the solar flare spectral analysis.

Rodgers, E. M.; Bailey, S. M.; Warren, H. P.; Woods, T. N.; Eparvier, F. G.

2006-05-01

288

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

289

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

290

Simulation Study of Effects of Solar Irradiance and Sea Surface Temperature on Monsoons and Global Circulation  

NASA Technical Reports Server (NTRS)

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.

Sud, Y. C.; Walker, G. K.; Mehta, V.; Lau, W. K.-M.; Einaudi, Franco (Technical Monitor)

2001-01-01

291

Optical Search for Extraterrestrial Intelligence with Air Cerenkov Telescopes  

NASA Astrophysics Data System (ADS)

We propose using large Air Cerenkov telescopes (ACTs) to search for optical, pulsed signals from extraterrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of solar luminosities at a distance of 100 pc. The field of view for giant ACTs can be on the order of 10 square degrees, and they will be able to monitor 10-100 stars simultaneously for nanosecond pulses of about 6th magnitude or brighter. Using the Earth's diameter as a baseline, orbital motion of the planet could be detected by timing the pulse arrivals.

Eichler, David; Beskin, Gregory

2001-12-01

292

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

NASA Astrophysics Data System (ADS)

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% .

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

2011-12-01

293

A local proton irradiation model for isotopic anomalies in the solar system  

NASA Technical Reports Server (NTRS)

An attempt is made to explain the O-16 and Al-26 anomalies observed in solar-system bodies in the framework of a local irradiation model wherein a small amount of solar system matter of normal isotopic composition was irradiated by energetic protons from the primeval sun. Several isotopic constraints are summarized with which the model should be consistent, and a proton energy distribution and fluence and a target elemental composition are chosen such that the extraordinary component produced by irradiation satisfies the constraints. Detailed attention is given to the relevant oxygen reactions, Al-26 production, and effects of proton irradiation on isotopes of Mg, Ca, and Ba. A scenario is outlined which satisfies all the constraints. Consequences of the model are discussed with respect to the isotopic anomalies observed in Allende inclusions.

Lee, T.

1978-01-01

294

High resolution laser beam induced current images under trichromatic laser radiation: Approximation to the solar irradiation  

NASA Astrophysics Data System (ADS)

A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

Navas, F. J.; Alcántara, R.; Fernández-Lorenzo, C.; Martín-Calleja, J.

2010-03-01

295

Medium-Energy Nuclear Data to Decipher the Cosmic Ray Record in Extraterrestrial Matter  

Microsoft Academic Search

A survey is given on the application of medium-energy nuclear data to the interpretation of cosmogenic nuclides in extraterrestrial matter. Cosmogenic nuclides in extraterrestr ial matter provide a wealth of information on the exposure and collision histories of small objects in space and on the history of the solar and galactic cosmic radiation itself. The interpreta- tion of the observed

R. MICHEL; I. LEYA

296

Thin film silicon solar cells for space applications: Study of proton irradiation and thermal annealing effects on the characteristics of solar cells and individual layers  

Microsoft Academic Search

The paper reports on the effects of a proton irradiation campaign on a series of thin-film silicon solar cells (single- and double-junction). The effect of subsequent thermal annealing on solar cells degraded by proton irradiation is investigated. A low-temperature annealing behaviour can be observed (at temperatures around 100 to 160°C) for microcrystalline silicon solar cells. To further explore this effect,

J Kuendig; M Goetz; A Shah; L Gerlach; E Fernandez

2003-01-01

297

The solar ultraviolet spectral irradiance monitor (SUSIM) experiment on board the Upper Atmosphere Research Satellite (UARS)  

NASA Technical Reports Server (NTRS)

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.

Brueckner, G. E.; Edlow, K. L.; Floyd, L. E., IV; Lean, J. L.; Vanhoosier, M. E.

1993-01-01

298

High-energy and high-fluence proton irradiation effects in silicon solar cells  

Microsoft Academic Search

We have examined proton irradiation damage in high-energy (1–10 MeV) and high-fluence (?1013 cm?2) Si n+-p-p+ structure space solar cells. Radiation testing has revealed an anomalous increase in short-circuit current Isc followed by an abrupt decrease and cell failure, induced by high-fluence proton irradiation. We propose a model to explain these phenomena by expressing the change in carrier concentration p

Masafumi Yamaguchi; Stephen J. Taylor; Ming-Ju Yang; Sumio Matsuda; Osamu Kawasaki; Tadashi Hisamatsu

1996-01-01

299

Electron and proton irradiation-induced degradation of epitaxial InP solar cells  

Microsoft Academic Search

The degradation of epitaxial, shallow homojunction n+p InP solar cells under 1 MeV electron and 3 MeV proton irradiation is presented. The data measured under 3 MeV proton irradiation are analyzed in terms of displacement damage dose which is the product of the particle fluence and the calculated non-ionizing energy loss (NIEL)[1]. A characteristic proton degradation curve is derived from

R. J. Walters; S. R. Messenger; H. L. Cotal; G. P. Summers; E. A. Burke

1996-01-01

300

Irradiation and Measurement of GaAs-Based Solar Cells at Low Intensity, Low Temperature (LILT)  

Microsoft Academic Search

This paper presents measurement and analysis of single junction GaAs and triple junction InGaP\\/GaAs\\/Ge solar cells after irradiation under low temperature and low intensity (LILT) conditions. The goal of these experiments was to quantify any annealing affects that might emerge after irradiation at low temperature and subsequent measurement after room temperature anneal. This is an important consideration for facilities that

S. Messenger; J. Tischler; M. Imaizumi; R. Harris

301

?-ray irradiation in the early Solar System and the conundrum of the 176Lu decay constant  

Microsoft Academic Search

When recent geological calibrations of the 176Lu decay constant are used, the 176Lu–176Hf ages of chondrites are consistently 4% too old (?4.75Ga). Here, we suggest that this discrepancy reflects the photoexcitation of the long-lived 176Lu ground state to the short-lived isomeric state (T1\\/2=3.7h) by ?-rays irradiating early condensates. Irradiation may have been of solar origin and taking place at the

Francis Albarède; Erik E. Scherer; Janne Blichert-Toft; Minik Rosing; Alexandre Simionovici; Martin Bizzarro

2006-01-01

302

Spectral response of InP\\/Si solar cells irradiated to high proton fluences  

Microsoft Academic Search

InP\\/Si solar cells have been irradiated with 3 MeV protons to very large fluences where carrier removal, instead of decreases in minority carrier diffusion length, dominates the radiation response. In this regime, radiation-induced expansion of the base depletion width causes I sc to increase above the pre-irradiation level before falling catastrophically to zero. Current-voltage (IV), capacitance-voltage (CV), quantum efficiency (QE),

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

1997-01-01

303

Quarantine provisions for unmanned extra-terrestrial missions  

NASA Technical Reports Server (NTRS)

This document sets forth requirements applicable to unmanned planetary flight programs which are necessary to enable the Associate Administrator for Space Science to fulfill those responsibilities pertaining to planetary quarantine as stated in NPD 8020.7 and NPD 8020.10A. This document is specifically directed to the control of terrestrial microbial contamination associated with unmanned space vehicles intended to encounter, orbit, flyby, or otherwise be in the vicinity of extra-terrestrial solar system bodies. The requirements of this document apply to all unmanned planetary flight programs. This includes solar system exploratory missions to the major planets as well as missions to planet satellites, or to other solar system objects that may be of scientific interest. This document is not applicable to terrestrial (including lunar) missions and manned missions. NASA officials having cognizance of applicable flight programs will invoke these requirements in such directives or contractual instruments as may be necessary to assure their implementation.

1976-01-01

304

Solar irradiance in the stratosphere - Implications for the Herzberg continuum absorption of O2  

NASA Technical Reports Server (NTRS)

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.

Frederick, J. E.; Mentall, J. E.

1982-01-01

305

Towards the automatic identification of cloudiness condition by means of solar global irradiance measurements  

NASA Astrophysics Data System (ADS)

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 exhibit large variability in the solar global irradiance measured at ground and, therefore, in the kt index, the algorithm is based, along with the value of the kt index, on the local variability. This variability was locally computed as the coefficient of variation of a two-neighbor window around each measurement. The consideration of both, the value of kt index and its local variability, highly improves previous classifications consisting in applying fixed thresholds to the kt index value. The proposed algorithm is applied to certain selected cases and compared to classifications proposed by other authors.

Sanchez, G.; Serrano, A.; Cancillo, M. L.

2010-09-01

306

Coupling of the SORCE space-borne spectral radiometer with the SUNRISE model to study solar spectral irradiance variation  

Microsoft Academic Search

The SIM (Spectral Irradiance Monitor) on the SORCE mission (SOlar Radiation and Climate Experiment) will provide 4 spectra per day of top of the atmosphere solar spectral irradiance in the 200 to 2000 nm region for its expected 5-year mission life. SIM is a prism spectrometer with a spectral resolution ranging from 0.25 nm at 200 nm to 33 nm

J. Harder; J. Fontenla; G. Lawrence; P. Fox; O. White; T. Woods; G. Rottman

2003-01-01

307

Solar Irradiance Anomalies Caused by Clear-Sky Transmission Variations above Mauna Loa: 1958–99  

Microsoft Academic Search

The clear-sky transmission of the atmosphere contributes to determining the amount of solar irradiance that reaches various levels in the atmosphere, which in turn is fundamental to defining the climate of the earth. As of the end of 1999, sustained clear-sky solar transmission over the mid-Pacific, as viewed from Mauna Loa, Hawaii, reached its highest level of clarity since before

Ellsworth G. Dutton; Barry A. Bodhaine

2001-01-01

308

27-day variations observed in solar U.V. (120-300 nm) irradiance  

Microsoft Academic Search

A Fourier-transform analysis of 256 days of SME solar irradiance data (115-303 nm) provides an estimate of the root-mean-square 27-day solar variation. The magnitude of this 27-day variation exceeds + or - 10 percent at 120 nm and decreases with increasing wavelength to less than 1 percent above 260 nm. Qualitative aspects of the analysis include a striking decrease in

G. J. Rottman

1983-01-01

309

20th century changes in surface solar irradiance in simulations and observations  

Microsoft Academic Search

The amount of solar irradiance reaching the surface is a key parameter in the hydrological and energy cycles of the Earth's climate. We analyze 20th Century simulations using nine state-of-the-art climate models and show that all models estimate a global annual mean reduction in downward surface solar radiation of 1-4 W\\/m2 at the same time that the globe warms by

A. Romanou; B. Liepert; G. A. Schmidt; W. B. Rossow; R. A. Ruedy; Y. Zhang

2007-01-01

310

The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells  

Microsoft Academic Search

Regions of lattice disorder produced in lithium-doped float-zone melted n\\/p-type silicon solar cells by irradiation with mono-energetic\\u000a neutrons at doses between 1010 and 1013\\/cm2 have been studied. The defect regions were revealed by chemically etching the surface of the solar cells and by observing\\u000a carbon replicas in an electron microscope. It was found that the defect density increased with increasing

S. Ghosh; G. A. Sargent

1972-01-01

311

On the Connection between Solar Spectral Irradiance and Planetary Wave Drag  

Microsoft Academic Search

An ever-increasing body of evidence shows that changes in solar spectral irradiance (SSI) over the 11-year solar cycle (SC) can produce changes in stratospheric ozone. Changes in stratospheric ozone can in turn produce changes in planetary wave drag (PWD) via wave-induced ozone heating, which was recently expounded upon in a paper by Nathan and Cordero (2007, JGR-Atmospheres). Because SSI-induced changes

T. R. Nathan; J. Albers; E. Cordero

2007-01-01

312

Nano-scale current voltage characteristics of thin film solar cell with light irradiations  

Microsoft Academic Search

Nano-scale current voltage (I–V) characteristics of hydrogenated amorphous silicon (a-Si:H) solar cells were studied with and without light irradiations by using conductive Atomic Force Microscope (conductive-AFM). To obtain proper I–V characteristics, electrical contacts between the n-layer of the a-Si solar cells and the cantilever of the AFM were modified by depositing ZnO films with the thickness of 20nm on the

Masato Kawai; Tomohiro Kawakami; Tomoya Inaba; Fumitaka Ohashi; Hironori Natsuhara; Takashi Itoh; Shuichi Nonomura

2010-01-01

313

ACRIM total solar irradiance satellite composite validation versus TSI proxy models  

NASA Astrophysics Data System (ADS)

The satellite total solar irradiance (TSI) database provides a valuable record for investigating models of solar variation used to interpret climate changes. The 35-year ACRIM total solar irradiance (TSI) satellite composite time series has been revised using algorithm updates based on 13 years of accumulated mission experience and corrections to ACRIMSAT/ACRIM3 results for scattering and diffraction derived from recent testing at the Laboratory for Atmospheric and Space Physics/Total solar irradiance Radiometer Facility (LASP/TRF). The net correction lowers the ACRIM3 scale by ˜3000 ppm, in closer agreement with the scale of SORCE/TIM results (average total solar irradiance ?1361.5 W/m2). Differences between the ACRIM and PMOD TSI composites are investigated, particularly the decadal trending during solar cycles 21-22 and the Nimbus7/ERB and ERBS/ERBE results available to bridge the ACRIM Gap (1989-1992), are tested against a set of solar proxy models. Our findings confirm the following ACRIM TSI composite features: (1) The validity of the TSI peak in the originally published ERB results in early 1979 during solar cycle 21; (2) The correctness of originally published ACRIM1 results during the SMM spin mode (1981-1984); (3) The upward trend of originally published ERB results during the ACRIM Gap; (4) The occurrence of a significant upward TSI trend between the minima of solar cycles 21 and 22 and (5) a decreasing trend during solar cycles 22-23. The same analytical approach does not support some important features of the PMOD TSI composite: (1) The downward corrections applied to the originally published ERB and ACRIM1 results during solar cycle 21; (2) The step function sensitivity change in ERB results at the end-of-September 1989; (3) The downward trend of ERBE results during the ACRIM Gap and (4) the use of ERBE results to bridge the ACRIM Gap. Our analysis provides a first order validation of the ACRIM TSI composite approach and its 0.037 %/decade upward trend during solar cycles 21-22. The implications of increasing TSI during the global warming of the last two decades of the 20th century are that solar forcing of climate change may be a significantly larger factor than represented in the CMIP5 general circulation climate models.

Scafetta, Nicola; Willson, Richard C.

2014-04-01

314

Limitation of Ground-based Estimates of Solar Irradiance Due to Atmospheric Variations  

NASA Technical Reports Server (NTRS)

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.

Wen, Guoyong; Cahalan, Robert F.; Holben, Brent N.

2003-01-01

315

Analysis of direct to diffuse partitioning of global solar irradiance at the radiometric station in Badajoz (Spain)  

NASA Astrophysics Data System (ADS)

This study is aimed at the analysis of the partitioning of global solar irradiance into its direct and diffuse components at the radiometric station in Badajoz (Spain). The detailed knowledge of the solar radiation field is of increasing interest in Southern Europe due to its use as renewable energy. In particular, the knowledge of the solar radiation partitioning into direct and diffuse radiation has become a major demand for the design and suitable orientation of solar panels in solar power plants. In this study the first measurements of solar diffuse irradiance performed in the radiometric station in Badajoz (Spain) are presented and analyzed in the framework of the partitioning of solar global radiation. Thus, solar global and diffuse irradiance were measured at one-minute basis from 23 November 2009 to 31 March 2010. Solar irradiances were measured by two Kipp&Zonen CMP11 pyranometers, using a Kipp&Zonen CM121 shadow ring for the measurements of solar diffuse irradiance. Diffuse measurements were corrected from the solid angle hidden by the ring and direct irradiance was calculated as the difference between global and diffuse measurements. Irradiance was obtained from the pyranomenters by applying calibration coefficients obtained in an inter-comparison campaign performed at INTA/El Arenosillo, in Huelva (Spain), last September 2009. There, calibration coefficients were calculated using as a reference a CMP11 pyranometer which had been previously calibrated by the Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre in Switzerland. In order to study the partitioning of the solar radiation, the global and diffuse irradiances have been analyzed for three typical different sky conditions: cloud-free, broken clouds and overcast. Particular days within the period of study have been selected by visual inspection. Along with the analysis of the global and diffuse irradiances themselves, ratios of these irradiances to the downward irradiance at the top of the atmosphere have also been analyzed. Several interesting features have been found. It is particularly worth to note the decreasing relative contribution of the direct component to the global irradiance as the solar zenith angle increases, due to a longer path crossed within the atmosphere. In broken clouds and overcast conditions, the diffuse component becomes the major contribution to the irradiance being the high-frequency variability the main difference between both type of cases. While in overcast conditions the global irradiance remains remarkably low, under broken clouds the global irradiance shows a very high variability frequently reaching values higher than the irradiance at the top of the atmosphere, due to multi-reflection phenomenon. The present study contributes to a better knowledge of the radiation field and its partitioning, involving original high-frequency measurements.

Sanchez, G.; Cancillo, M. L.; Serrano, A.

2010-09-01

316

Nuclear Power: Key to Man's Extraterrestrial Civilization.  

National Technical Information Service (NTIS)

The start of the Third Millennium will be highlighted by the establishment of man's extraterrestrial civilization with three technical cornerstones leading to the off-planet expansion of the human resource base. These are (1) the availability of compact e...

J. A. Angelo D. Buden

1982-01-01

317

Unidentified flying objects and extraterrestrial life  

NASA Astrophysics Data System (ADS)

Discusses efforts to find intelligent life on other planets and theories on this topic and describes UFO sightings and other phenomena that are given as evidence of extraterrestrial visitors among us.

Marsh, Carole

318

Unidentified flying objects and extraterrestrial life  

Microsoft Academic Search

Discusses efforts to find intelligent life on other planets and theories on this topic and describes UFO sightings and other phenomena that are given as evidence of extraterrestrial visitors among us.

Carole Marsh

1996-01-01

319

Low temperature quantum efficiency measurements on irradiated multijunction solar cells  

Microsoft Academic Search

This paper presents quantum efficiency (QE) measurements and analyses on monolithic triple junction (3J) InGaP\\/GaAs\\/Ge solar cells under both room (300K) and low temperature (130K) conditions. In measuring the quantum efficiency of multijunction solar cells, one must be careful to use the proper bias conditions to isolate the subcell of interest. This may be achieved by using external light sources

S. R. Messenger; J. H. Warner; P. P. Jenkins; R. J. Walters; J. R. Lorentzen

2008-01-01

320

Subcanopy Solar Radiation Model: an irradiation model for predicting light in heavily vegetated landscapes  

NASA Astrophysics Data System (ADS)

Solar radiation flux, irradiance, affects many biological (e.g. photosynthesis, germination, metabolism) and hydrological (e.g. snow melt, water cycling) processes. Models of these processes often require data at the watershed scale. GIS based solar models that predict irradiation at the watershed scale take topographic shading into account, but do not account for vegetative shading. Methods that quantify subcanopy irradiation do so only at a single point. Further, calibrating the subcanopy models require significant field effort and knowledge of individual species characteristics (leaf area index, mean leaf angle, clumping factor, etc.). Upscaling from point values to watersheds is a significant source of uncertainty. We propose an approach to modeling irradiation that uses airborne LiDAR to estimate canopy openness as a Light Penetration Index (LPI). We coupled LPI with the GRASS GIS r.sun solar model to produce the Subcanopy Solar Radiation model (SSR). SSR accounts for both topographic shading and vegetative shading at the watershed scale. Output is 52 raster maps (one per week) of 24 hours of irradiation (watt-hours/m2). We calibrated the r.sun model to a weather station at our field site and to field measurements of direct and diffuse solar radiation taken for 24 hours at the weather station site. We validate predictions of the SSR by comparing modeled output to field measurements and to a standard method for point estimation of subcanopy radiation, hemispherical photographs processed with Gap Light Analyzer 2.0 (GLA). Based on ANCOVA analysis, SSR and GLA models exhibit a similar linear relationship with field data, and the models predict similar total solar radiation flux across the range of canopy openness. With similar quality to a standard point method, but with greatly expanded spatial coverage, SSR should become a useful tool in watershed analysis.

Bode, C. A.; Limm, M. P.; Finlay, J. C.; Power, M.

2012-12-01

321

Estimation of UV-B irradiation from total global solar meteorological data in central Spain  

NASA Astrophysics Data System (ADS)

Measurements of solar ultraviolet-B (UV-B) in the range (280-315 nm) and total global solar irradiation (G) for the period 2002-2006 in a continental Mediterranean environment have been analyzed. UV-B and G data have been recorded at the Low Atmosphere Research Laboratory, Valladolid, Spain, using a YES UVB-1 pyranometer and a Kipp&Zonen CM-6 radiometer, respectively. According to the cloud conditions, the time data series shows that the highest UV-B values are obtained in June and the lowest ones are obtained in December. A comparison of monthly UV-B values reveals that some summer months show more dispersion than winter ones. An empirical relationship between UV-B and G was established to estimate the daily UV-B irradiation from commonly measured daily total global solar irradiation. The annual cycle effects of the solar zenith angle and the ozone total column have been taken into account. A correction factor that depends on the daily total ozone column has been included in the relationship between UV-B and total global solar irradiation. The performance of this relationship has been evaluated comparing estimated and measured UV-B values in three different stations. Scatterplot, root-mean-square error (RMSE), mean bias error (MBE), and linear regression correlation coefficient have been used to compare measured and estimated values. The results of this comparison show that the correlation coefficients were similar to 1 while the RMSE ranges between 2.10 kJ m-2 and 1.94 k Jm-2 and, in percentage, 9.18% and 7.64%, respectively. According to these results, it can be concluded that total global solar irradiation is an appropriate variable to obtain UV-B daily values in places where ultraviolet radiation is not measured or to extend the existing data set back in time.

Bilbao, Julia; de Miguel, Argimiro

2010-01-01

322

Anomalous effects in silicon solar cell irradiated by 1-MeV protons  

NASA Technical Reports Server (NTRS)

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.

Kachare, R.; Anspaugh, B. E.

1989-01-01

323

Interplanetary survival probability of Aspergillus terreus spores under simulated solar vacuum ultraviolet irradiation  

NASA Astrophysics Data System (ADS)

This work is a part of ESA/EU SURE project aiming to quantify the survival probability of fungal spores in space under solar irradiation in the vacuum ultraviolet (VUV) (110-180 nm) spectral region. The contribution and impact of VUV photons, vacuum, low temperature and their synergies on the survival probability of Aspergillus terreus spores is measured at simulated space conditions on Earth. To simulate the solar VUV irradiation, the spores are irradiated with a continuous discharge VUV hydrogen photon source and a molecular fluorine laser, at low and high photon intensities at 10 15 photon m -2 s -1 and 3.9×10 27 photons pulse -1 m -2 s -1, respectively. The survival probability of spores is independent from the intensity and the fluence of photons, within certain limits, in agreement with previous studies. The spores are shielded from a thin carbon layer, which is formed quickly on the external surface of the proteinaceous membrane at higher photon intensities at the start of the VUV irradiation. Extrapolating the results in space conditions, for an interplanetary direct transfer orbit from Mars to Earth, the spores will be irradiated with 3.3×10 21 solar VUV photons m -2. This photon fluence is equivalent to the irradiation of spores on Earth with 54 laser pulses with an experimental ˜92% survival probability, disregarding the contribution of space vacuum and low temperature, or to continuous solar VUV irradiation for 38 days in space near the Earth with an extrapolated ˜61% survival probability. The experimental results indicate that the damage of spores is mainly from the dehydration stress in vacuum. The high survival probability after 4 days in vacuum (˜34%) is due to the exudation of proteins on the external membrane, thus preventing further dehydration of spores. In addition, the survival probability is increasing to ˜54% at 10 K with 0.12 K/s cooling and heating rates.

Sarantopoulou, E.; Gomoiu, I.; Kollia, Z.; Cefalas, A. C.

2011-01-01

324

Effects of the solar spectral irradiance changes during the first half of 20th century on chemistry and climate  

NASA Astrophysics Data System (ADS)

The attribution of climate and chemistry changes in the past requires understanding of the role of different natural forcing such as volcanic eruptions and solar irradiance. The first half of the 20th century is characterized by an increase in solar activity (and presumably solar irradi-ance) reaching the maximum in the year 1957. Therefore, to elucidate the contribution of the solar irradiance to the climate change we have carried out two 60-year long transient ensemble simulations with the chemistry-climate model SOCOL spanning the first half of 20th century, driven by the prescribed time evolution of the sea surface temperature, sea ice distribution, volcanic aerosols, greenhouse gases, ozone depleting substances, sources of CO and NOx, land use, and quasi-biennial oscillation. For the first run we have applied constant solar spectral irradiance, while the second run has been driven by time dependent solar spectral irradiance. The simulated time series of different atmospheric quantities have been analyzed to estimate the climate and chemistry response to the changes of solar spectral irradiance. The analyses showed statistically significant solar signal from the mesosphere down to the surface. The max-imum ozone response ( 4%) is found in the tropical middle stratosphere, while the temperature response maximizes in the tropical stratopause reaching 1.2K. The contribution of the solar spectral irradiance variability to the global mean surface temperature changes is rather small; however, the downward propagation of the solar signal leads to noticeable land surface temper-ature response over some geographical locations. Its magnitude can reach 0.6 K over Siberia, Scandinavia, Central USA and Canada. The cooling due to solar irradiance is observed over Northern Canada, China and Northern Africa.

Rozanov, Eugene; Dorf, Davos; Arfeuille, F.; Brünnimann, S.; Calisto, M.; Egorova, T.; Fischer, A.; Heckendorn, P.; Luo, B.-P.; Peter, T.; Rozanov, E.; Shapiro, A. V.; Schmutz, W.; Schraner, M.; Stenke, A.; Zubov, V.

325

The Solar Spectral Irradiance Measured on Board the International Space Station and the Picard Spacecraft  

NASA Astrophysics Data System (ADS)

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.

Thuillier, G. O.; Bolsee, D.; Schmidtke, G.; Schmutz, W. K.

2011-12-01

326

The biological universe. The twentieth century extraterrestrial life debate and the limits of science.  

NASA Astrophysics Data System (ADS)

Throughout the twentieth century, from the furor over Percival Lowell's claim of canals on Mars to the sophisticated Search for Extraterrestrial Intelligence, otherworldly life has often intrigued and occasionally consumed science and the public. Does 'biological law' reign throughout the universe? Are there other histories, religions, and philosophies outside of those on Earth? Do extraterrestrial minds ponder the mysteries of the universe? The attempts to answer these often asked questions form one of the most interesting chapters in the history of science and culture, and this is the first book to provide a rich and colorful history of those attempts during the twentieth century. Covering a broad range of topics, including the search for life in the solar system, the origins of life, UFOs, and aliens in science fiction, the author shows how the concept of extraterrestrial intelligence is a world view of its own, a 'biophysical cosmology' that seeks confirmation no less than physical views of the universe.

Dick, S. J.

327

The biological universe: the twentieth-century extraterrestrial life debate and the limits of science  

NASA Astrophysics Data System (ADS)

Throughout the twentieth century, from the furor over Percival Lowell's claim of canals on Mars to the sophisticated Search for Extraterrestrial Intelligence, otherworldly life has often intrigued and occasionally consumed science and the public. Does `biological law' reign throughout the universe? Are there other histories, religions, and philosophies outside of those on Earth? Do extraterrestrial minds ponder the mysteries of the universe? The attempts toanswer these often asked questions form one of the most interesting chapters in the history of science and culture, and The Biological Universe is the first book to provide a rich and colorful history of those attempts during the twentieth century. Covering a broad range of topics, including the search for life in the solar system, the origins of life, UFOs, and aliens in science fiction, Steven J. Dick shows how the concept of extraterrestrial intelligence is a world view of its own, a `biophysical cosmology' that seeks confirmation no less than physical views of the universe.

Dick, Steven J.

328

Retrieval of Cirrus Properties from Solar Spectral Irradiance During CRYSTAL-FACE  

Microsoft Academic Search

We examine spectrally resolved solar irradiance measured from above (NASA ER-2) and below (CIRPAS Twin Otter) tropical anvils during CRYSTAL-FACE in order to derive relationships between the scattered (reflected and transmitted) radiation and cirrus microphysical properties. Retrieved parameters are interpreted with respect to other remote sensing methods and to microphysical quantities obtained in situ. In particular we compare with simultaneous

P. Pilewskie; H. Guan; S. Platnick; P. Yang; R. Bergstrom; M. Wendisch

2003-01-01

329

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

National Technical Information Service (NTIS)

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 t...

R. P. Cebula M. T. DeLand E. Hilsenrath

1996-01-01

330

The Effect of Solar Irradiance on the Mortality of Phakopsora pachyrhizi Urediniospores  

Microsoft Academic Search

Isard, S. A., Dufault, N. S., Miles, M. R., Hartman, G. L., Russo, J. M., De Wolf, E. D., and Morel, W. 2006. The effect of solar irradiance on the mortality of Phakopsora pachyrhizi uredin- iospores. Plant Dis. 90:941-945. Soybean rust, caused by Phakopsora pachyrhizi, may be the most important foliar disease of soybean. Within the last 10 years, the

S. A. Isard; N. S. Dufault; M. R. Miles; G. L. Hartman; J. M. Russo; E. D. De Wolf; W. Morel

2006-01-01

331

Solar transmittance measurements using an integrating sphere with broad area irradiation  

Microsoft Academic Search

This paper examines the broad area irradiation method for measuring solar transmittance of advanced glazing materials. It shows that the apparent transmittance measured by this method is the product of the true transmittance, and two factors related to the reflectance of the sample. Not accounting for these other factors may lead to errors. Methods for reducing and correcting these errors

D. I. Milburn; K. G. T. Hollands

1994-01-01

332

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

NASA Astrophysics Data System (ADS)

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 COSI as a tool for modeling the variability of the irradiance, assuming that the latter is determined by the evolution of the solar surface magnetic field. The theoretical results are compared with the PREMOS and LYRA measurements. Finally we show that COSI and other semi-empirical and empirical models allow to reconstruct the entire solar spectrum from the observations in a few passbands. Hence the PREMOS and LYRA measurements can be used as a proxies for the nowcasting of the solar irradiance (UV-visible-IR) with the high cadence rate and spectral resolution.

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

333

Coproduction of volatiles and metals from extraterrestrial materials  

NASA Technical Reports Server (NTRS)

Two main efforts in support of the general goals of SERC/culpr are presented. Investigations of processes for the coproduction of metals from extra-terrestrial materials in conjunction with plausible schemes for oxygen extraction continue. The principal emphasis was on the extraction and purification of iron from the ilmenite reduction process for oxygen, from the cathode metal deposits made in the magma electrolysis process for oxygen, and from native ferrous metal alloys on the moon and asteroids. All work on the separation and purification of ferrous metals was focussed upon the gaseous carbonyl process, a scheme that involves only temperatures attainable by passive thermal control. The exploration of a variety of schemes was initiated, involving the use of several different propulsion options and both propulsive and aerobraking capture at earth, for return of extraterrestrial resources to earth orbits. In addition, the search for new opportunities in space resource utilization continues. Examples include the continuation of work underway on: (1) the feasibility of locating solar power satellites in highly eccentric earth orbit; (2) the energetics of extracting the potential clean fusion fuel He-3 from the atmosphere for return to earth; and (3) the utility of a nuclear steam rocket (using non-terrestrial water as the working fluid) for transportation in the inner solar system.

Lewis, John S.

1991-01-01

334

The spectral effects of clouds on solar irradiance  

NASA Astrophysics Data System (ADS)

Knowledge of the spectral attenuation associated with clouds is important for accurate estimates of natural irradiance at the Earth's surface. We compare spectral measurements of visible downwelling irradiance, under varying sky conditions at Halifax, Nova Scotia, Canada, with results from a clear-sky model. The spectral effect of clouds is estimated by taking the ratio of the measurements to the modeled irradiances and removing spectrally consistent instrumental effects and errors in the model. Empirical relationships derived between the spectral cloud effect and both CF, the cloud factor (the ratio of measured to modeled irradiances at 490 nm), and f, the fraction of sky covered by cloud, were found to follow a wavelength (?) dependence of the form a(CF or f)+b(CF or f)(?/490)-4 in the 412-700 nm wavelength range. Both this relationship and a previously published linear relationship were found to be inadequate for describing cloudy irradiance data from the Bering Sea, indicating that the spectral effect of clouds can vary with cloud type and location. We show here that the spectral cloud effect can be mimicked by using a clear-sky model and changing the magnitude of the sky reflectivity or the spectral shape and magnitude of the ground albedo within the model. An investigation of the effects of cloud-dependent changes in irradiance spectra on calculations of bio-optical properties is also presented. Estimates of chlorophyll concentration from near-surface radiances are found to vary by up to 30%, whereas the effects on estimates of photosynthetically available and usable radiation at the sea surface are negligible.

Bartlett, Jasmine S.; Ciotti, Áurea M.; Davis, Richard F.; Cullen, John J.

1998-12-01

335

Infrared Cavity Radiometer Reflectometry in Support of Total Solar Irradiance Instruments  

NASA Astrophysics Data System (ADS)

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 ?m. 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.

Hanssen, L. M.; Zeng, J.; Wilthan, B.; Morrill, J. S.; Kopp, G.

2011-12-01

336

Influence of solar UV irradiance on quasi-biennial oscillations in the Earth's atmosphere  

NASA Astrophysics Data System (ADS)

A study of relationships between variations in the solar ultraviolet irradiance and quasi-biennial oscillations (QBO) in the Earth's atmosphere has been carried out by using the composite MgII index as a proxy of the solar UV irradiance. Detail analysis of changes in the stratospheric wind directions at layers from 10 mB to 70 mB for 1978-2001 showed that the wind changes start at higher altitudes and go down to lower ones, the wind intensity being the greatest in layer of the maximum ozone content (about 20 mB). The definite relationship between periodicity of changes in the solar UV irradiance and QBO is found: the averaged UV irradiance is obviously larger for the east QBO phase than for the west QBO phase. The reversal of stratospheric winds proceeds from the top to down with the certain ciclicity, and efficiency of the UV irradiation influence on stratosphere seems to be different at various stages of this ciclicity. As a result, the character and duration of the mean zonal wind direction in the equatorial stratosphere is determined by proper combination of the UV variation and seasonal changes in atmospheric circulation.

Gabis, I.; Troshichev, O.

2003-04-01

337

A model for light distribution and average solar irradiance inside outdoor tubular photobioreactors for the microalgal mass culture  

Microsoft Academic Search

A mathematical model to estimate the solar irradiance profile and average light intensity inside a tubular photobioreactor under outdoor conditions is proposed, requiring only geographic, geometric, and solar position parameters. First, the length of the path into the culture traveled by any direct or disperse ray of light was calculated as the function of three variables: day of year, solar

F. G. A. Fernandez; F. G. Camacho; J. A. S. Perez; J. M. F. Sevilla; E. M. Grima

1997-01-01

338

Chemical and dynamical response to the 11-year variability of the solar irradiance simulated with a chemistry-climate model  

Microsoft Academic Search

Atmospheric effects of the solar irradiance variations during 11-year solar cycle are investigated using a chemistry-climate model. The model is enhanced by a more detailed parameterization of the oxygen and ozone UV heating rates. The simulated ozone response to the imposed solar forcing shows a positive correlation in the tropical stratosphere and a negative correlation in the tropical mesosphere, in

T. Egorova; E. Rozanov; E. Manzini; M. Haberreiter; W. Schmutz; V. Zubov; T. Peter

2004-01-01

339

Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors  

NASA Technical Reports Server (NTRS)

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.

Deland, Matthew T.; Cebula, Richard P.

1994-01-01

340

Influence of synoptic weather patterns on solar irradiance variability in Europe  

NASA Astrophysics Data System (ADS)

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 poorly represented by the GWL models, but in northern Europe, the GWL model recreates observed decadal solar variability well. This finding suggests that natural and/or anthropogenic variations in circulation patterns have influenced solar dimming and brightening to a higher degree in the north than in the rest of Europe.

Parding, Kajsa; Hinkelman, Laura; Liepert, Beate; Ackerman, Thomas; Dagestad, Knut-Frode; Asle Olseth, Jan

2014-05-01

341

The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements  

NASA Astrophysics Data System (ADS)

Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2), the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984) solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7) in the visible spectral range (415-650 nm), but it is +2.1% larger in the (370-415 nm) wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm), when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b) and SORCE/SIM (Harder et al., 2000) solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen -) with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm), -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002) our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

Gurlit, W.; Bösch, H.; Bovensmann, H.; Burrows, J. P.; Butz, A.; Camy-Peyret, C.; Dorf, M.; Gerilowski, K.; Lindner, A.; Noël, S.; Platt, U.; Weidner, F.; Pfeilsticker, K.

2005-07-01

342

The dependence of the surface solar irradiance on cloud and aerosol  

NASA Astrophysics Data System (ADS)

To quantify radiative forcing of aerosol and to investigate the dependence of the horizontal UV, visible and NIR on total optical depth (TOD) and cloudiness, narrowband surface solar irradiances were measured and analyzed for direct and diffuse component. A MFRSR (Multifilter Rotating Shadowband Ratiometer) was used to measure the global, direct and diffuse solar irradiances atone broadband of 391-955 nm and 6 narrowband channels of 412.8, 495.2, 611.9, 672.2, 869, 936.6 nm for a year from Jan. to Dec. in 2006 at Yonsei University in Seoul and a UV-MFRSR was used to measure irradiance at 7 narrowband channels of 299.1, 304.5, 310.7, 317.1, 323.8, 331.3, 367.4 nm in UV range during 7 months at the same location with the MFRSR.

Kim, Yun Mi; Kim, Jhoon; Cho, Hi Ku; Lee, Yun Gon; Koo, Ja Ho; Kim, Young Joon

2009-03-01

343

A status report on the analysis of the NOAA-9 SBUV/2 sweep mode solar irradiance data  

NASA Technical Reports Server (NTRS)

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.

Cebula, R. P.; Deland, M. T.; Schlesinger, B. M.; Hudson, R. D.

1990-01-01

344

Effects of solar UV irradiation on dynamics of ozone hole in Antarctica  

NASA Astrophysics Data System (ADS)

To study relationship between changes in solar ultraviolet (UV) irradiance and dynamics of the Antarctic ozone hole during the final breakup of the Antarctic polar vortex the composite Mg II index has been used as a proxy for the solar UV irradiance. The short-term changes in the UV-irradiation have been separated after removing the long- and middle term variations. Examination of maps of the total ozone distribution above Antarctica showed that the ozone hole collapse succeeds displacement of the hole center from the South Pole, where the absolute minimum of total ozone is usually located. Comparison with variations of the UV irradiation reveals that phase of the quick decay of the ozone hole is preceded by the maximal solar UV irradiation in course of the regular 27-days variation. Analysis of the vertical profiles of ozone density, temperature, wind speed and total column ozone above station Amundsen Scott showed that ozone hole is filled up in spring typically in two phases. During the first gradual phase the ozone filling occurs very slowly, whereas the second phase is characterized by sudden and sharp increase of the ozone content (about 50 100 Dobson units in few days). In this period the strong wind disturbances are observed in the higher stratosphere as well. Conclusion is made that rate of the ozone hole filling during the Antarctic later spring depends on the intensity of solar UV, and high level of the UV irradiation turns out to be sufficient to initiate the dynamical processes leading to the collapse of the winter circumpolar vortex.

Troshichev, O.; Gabis, I.

2005-01-01

345

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

346

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

NASA Technical Reports Server (NTRS)

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.

London, Julius

1994-01-01

347

SCIAMACHY solar irradiance observation in the spectral range from 240 to 2380nm  

NASA Astrophysics Data System (ADS)

SCIAMACHY (SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY) is part of the payload of ESA's Environmental Satellite ENVISAT which was launched into a sun-synchronous polar orbit on 2002-03-01. It is the first spaceborne instrument covering a wavelength range from 240 to 2380 nm thus including ultraviolet, visible and near infrared spectral regions. The main purpose of the instrument is to determine the amount and distribution of various trace gases and aerosol as well as cloud cover and cloud top height in Earth's atmosphere by measuring the atmospheric radiance in limb and nadir geometry. In addition several solar observations are performed with daily or orbital frequency that offer the possibility to monitor solar variations on a dense time grid. The presented results will cover the following topics:(a) Comparison of the solar irradiance measured by SCIAMACHY with other in-orbit instruments like SOLSTICE and SOLSPEC. (b) Comparison of the SCIAMACHY solar Mg II index with GOME and NOAA instruments. (c) Correlation of SCIAMACHY solar irradiance with the sun spot index. Together with the European ozone monitoring experiments GOME (launched 1995) and GOME2 (to be launched 2005) SCIAMACHY completes a triple of similar instruments ensuring a continuous record of solar and atmospheric observations starting in 1995 and ranging into the second decade of the 21st century.

Skupin, J.; Noël, S.; Wuttke, M. W.; Gottwald, M.; Bovensmann, H.; Weber, M.; Burrows, J. P.

348

Annealing results on low-energy proton-irradiated GaAs solar cells  

NASA Technical Reports Server (NTRS)

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.

Kachare, R.; Anspaugh, B. E.; O'Meara, L.

1988-01-01

349

A new technique for predicting silicon solar cell short-circuit currents at reference irradiance conditions  

NASA Astrophysics Data System (ADS)

A combined analytical/experimental technique for the prediction of silicon solar cell short circuit currents at any reference irradiance condition has been developed. Concurrent short-circuit current and spectral irradiance measurements are used to compute an approximate spectral response which can then be integrated with any desired reference spectral irradiance to predict the short-circuit current at the reference condition. Theoretical results show that absolute errors of less than + or - 1.5% are present when testing within the guidelines for the calibration of Type I primary reference cells presented in NASA TM 73702. Experimental results indicate that the use of standard glass cutoff filters OG1, RG2, and RG8 can be used for simple pyrheliometric measurements that allow calculation of sufficiently accurate irradiance functions so that the reference current prediction is repeatable within the accuracy of the pyrheliometer.

Lorentz, D. R.; Backus, C. E.

350

Irradiation and measurements of fluorinated ethylene-propylene-A on silicon solar cells in vacuum  

NASA Technical Reports Server (NTRS)

Silicon monoxide (SiO) coated silicon solar cells covered with fluorinated ethylene-propylene-A (FEP-A) were irradiated by 1-MeV electrons in vacuum. The effect of irradiation on the light transmittance of FEP-A was checked by measuring the short-circuit current of the cells while in vacuum after each dose increment, immediately after the irradiation, and again after a minimum elapsed time of 16 hr. The results indicated no apparent loss in transmission due to irradiation of FEP-A and no delamination from the SiO surface while the cells were in vacuum, but embrittlement of FEP-A occurred at the accumulated dose.

Marsik, S. J.; Broder, J. D.

1975-01-01

351

An investigation of short period oscillations of the solar irradiance and their time variations  

NASA Technical Reports Server (NTRS)

Measurements of solar irradiance fluctuations by the Active Cavity Radiometer (ACRIM) instrument onboard the Solar Maximum Mission (SMM) show variations on a time scale of about 5 minutes due to solar p-mode oscillations, as well as longer-term variations related to solar magnetic activity. The question was studied whether the p-mode frequencies change with time as a result of changing solar structure associated with the activity cycle. The ACRIM data on SMM are particularly well-suited for this purpose, because the instrument operated continuously from February 1980 to December 1980 and again from May 1984 to the present. The main activity entailed a detailed study of the observational data to determine if a change in the p-mode frequencies is evident from the time of solar maximum to that of solar minimum. It was concluded that the measured eigenfrequencies were significantly higher during the 1980 time frame than during the 1984 to 1986 time frame. The conclusion that there is significant change in the eigenfrequencies with the activity cycle remains only tentative, and needs confirmation from analysis of more data during the upcoming solar maximum.

Noyes, Robert W.

1987-01-01

352

Infrared Spectroscopy of Extraterrestrial Materials  

NASA Astrophysics Data System (ADS)

Infrared spectroscopy is diagnostic of the mineralogy and structural properties of nearly all materials, whether terrestrial, planetary, interplanetary, or interstellar. Astronomical observations of extrasolar planetary system debris as well as features in the interstellar medium have revealed some mineralogical signatures, which are generally interpreted in comparison to predictions based on pure minerals. To complement those studies, we are measuring the infrared spectra of a wide range of extraterrestrial materials in the laboratory. The goals are (1) to form a new basis for interpreting extrasolar and interstellar material by comparison to the parent bodies of meteorites rather than pure minerals and (2) to determine the infrared properties of meteorites of as wide a range of types as possible in order to study which parent body properties and histories and physical processes can affect infrared spectra. Attenuated total reflectance (ATR) spectroscopy provides convenient measurement capabilities over the range of wavelengths and signal-to-noise that are directly comparable to the remote telescopic observations, 3-150 microns. The materials for the laboratory study were obtained from the NASA Antarctic Meteorite Curatorial Facility and supplemented by terrestrial crater rocks and tektites from private sources. The mid-infrared diagnostic features of silicate minerals are richly present in most samples. The far-infrared measurements, to date, indicate a dependence of absorbance on the degree of shock history. We will examine this effect with future experiments. If confirmed, the results could have implications for understanding mineralogy of extrasolar and interstellar dust, which is likely to have experienced shocks from hypervelocity collisions.

Reach, W. T.; Yesiltas, M.; Rossman, G. R.

2012-12-01

353

Mass mortality and extraterrestrial impacts  

NASA Technical Reports Server (NTRS)

The discovery of iridium enrichment at the Cretaceous/Tertiary boundary resulted in formulation of hypothesis of a cometary or asteroid impact as the cause of the biological extinctions at this boundary. Subsequent discoveries of geochemical anomalies at major stratigraphic boundaries like the Precambrian/Cambrian, Permian/Triassic, Middle/Late Jurassic, resulted in the application of similar extraterrestrial impact theories to explain biological changes at these boundaries. Until recently the major physical evidence, as is the location of the impact crater site, to test the impact induced biological extinction was lacking. The diameter of such a crater would be in the range of 60 to 100 km. The recent discovery of the first impact crater in the ocean provide the first opportunity to test the above theory. The crater, named Montagnais and located on the outer shelf off Nova Scotia, Canada, has a minimum diameter of 42 km, with some evidence to a diameter of more than 60 km. At the Montagnais impact site, micropaleontological analysis of the uppermost 80 m of the fall-back breccia represented by a mixture of pre-impact sediments and basement rocks which fills the crater and of the basal 50 m of post-impact marine sediments which overly the impact deposits, revealed presence of diversified foraminiferal and nannoplankton assemblages. The sediments which are intercalated within the uppermost part of the fall-back breccia, had to be deposited before the meteorite impact. The post-impact deposits were laid down almost immediately after the impact as also supported by the micropaleontological data. In conclusion, micropaleontological studies of sediments from the first submarine impact crater site identified in the ocean did not reveal any mass extinction or significant biological changes at the impact site or in the proximal deep ocean basin.

Jansa, L. F.; Gradstein, F. M.; Pierre-Aubry, M.

1988-01-01

354

Optical and Solar Cell Properties of Alpha-ray, Proton, and Gamma-ray Irradiated Cu(In,Ga)Se2 Thin Films and Solar Cells  

Microsoft Academic Search

The effects of alpha-ray, proton, and gamma-ray irradiation on the electrical properties of Cu(In,Ga)Se2 (CIGS) solar cells and the photoluminescence spectra of CIGS and CuInSe2 (CIS) thin films were investigated. Particle irradiation using alpha-ray and proton primarily degraded the interfaces of CIGS solar cells, even though the CIS and CIGS thin films did not degraded, in the case of a

Mutsumi Sugiyama; Toshihiro Yasuniwa; Hisayuki Nakanishi; Shigefusa F. Chichibu; Shinichi Kimura

2010-01-01

355

Reconstruction of the solar EUV irradiance as observed with PROBA2/LYRA  

NASA Astrophysics Data System (ADS)

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.

Haberreiter, Margit; Delouille, Veronique; Del Zanna, Giulio; Ermolli, Ilaria; Kretzschmar, Matthieu; Mampeay, Benjamin; Dominique, Marie; Schmutz, Werner

2014-05-01

356

A stochastic post-processing method for solar irradiance forecasts derived from NWPs models  

NASA Astrophysics Data System (ADS)

Solar irradiance forecast is an important area of research for the future of the solar-based renewable energy systems. Numerical Weather Prediction models (NWPs) have proved to be a valuable tool for solar irradiance forecasting with lead time up to a few days. Nevertheless, these models show low skill in forecasting the solar irradiance under cloudy conditions. Additionally, climatic (averaged over seasons) aerosol loading are usually considered in these models, leading to considerable errors for the Direct Normal Irradiance (DNI) forecasts during high aerosols load conditions. In this work we propose a post-processing method for the Global Irradiance (GHI) and DNI forecasts derived from NWPs. Particularly, the methods is based on the use of Autoregressive Moving Average with External Explanatory Variables (ARMAX) stochastic models. These models are applied to the residuals of the NWPs forecasts and uses as external variables the measured cloud fraction and aerosol loading of the day previous to the forecast. The method is evaluated for a set one-moth length three-days-ahead forecast of the GHI and DNI, obtained based on the WRF mesoscale atmospheric model, for several locations in Andalusia (Southern Spain). The Cloud fraction is derived from MSG satellite estimates and the aerosol loading from the MODIS platform estimates. Both sources of information are readily available at the time of the forecast. Results showed a considerable improvement of the forecasting skill of the WRF model using the proposed post-processing method. Particularly, relative improvement (in terms of the RMSE) for the DNI during summer is about 20%. A similar value is obtained for the GHI during the winter.

Lara-Fanego, V.; Pozo-Vazquez, D.; Ruiz-Arias, J. A.; Santos-Alamillos, F. J.; Tovar-Pescador, J.

2010-09-01

357

Solar total irradiance variations and the global sea surface temperature record  

SciTech Connect

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.

Reid, G.C. (National Oceanic and Atmospheric Administration, Boulder, CO (USA) Univ. of Colorado, Boulder (USA))

1991-02-20

358

Photo-recovery of electron-irradiated GaAs solar cells  

NASA Astrophysics Data System (ADS)

The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, independent of the coverslide coatings, are of particular importance in terms of the predictability of GaAs solar-array lifetime in space: ( 1) The GaAs/Ge solar cells used for this series of tests displayed a much higher radiation degradation than that predicted based on JPL Solar Cell Radiation Handbook data. Covered cells degraded more in Isc than did bare cells. Short-term illumination at 60 C did not produce significant recovery (-1%) of the radiation damage. (2) However, electron radiation damage to these GaAs solar celIs anneals at 40 C when exposed to approximately 1 sun AM0 UV light sources for extended periods. The effect appears to be roughly linear with time (-1% of lsc per 1000 UVSH), is large (greater than or equal to 3%), and has not yet saturated (at 3000 hours). This photo-recovery of radiation damage to GaAs solar cells is a new effect and potentially important to the spacecraft community. The figure compares the effects of extended UV on irradiated and unirradiated GaAs solar cells with INTELSAT-6 Si cells. The effect and its generality, the extent of and conditions for photo-recovery, and the implications of such recovery for missions in radiation environments have not yet been determined.

Meulenberg, Andrew

1995-10-01

359

Solar Irradiance Variability: Validation of Satellite-Based Assessment and Prospective Enhancements  

NASA Astrophysics Data System (ADS)

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.

Nonnenmacher, L.; Coimbra, C.

2013-12-01

360

Photo-recovery of electron-irradiated GaAs solar cells  

NASA Technical Reports Server (NTRS)

The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, independent of the coverslide coatings, are of particular importance in terms of the predictability of GaAs solar-array lifetime in space: ( 1) The GaAs/Ge solar cells used for this series of tests displayed a much higher radiation degradation than that predicted based on JPL Solar Cell Radiation Handbook data. Covered cells degraded more in Isc than did bare cells. Short-term illumination at 60 C did not produce significant recovery (-1%) of the radiation damage. (2) However, electron radiation damage to these GaAs solar celIs anneals at 40 C when exposed to approximately 1 sun AM0 UV light sources for extended periods. The effect appears to be roughly linear with time (-1% of lsc per 1000 UVSH), is large (greater than or equal to 3%), and has not yet saturated (at 3000 hours). This photo-recovery of radiation damage to GaAs solar cells is a new effect and potentially important to the spacecraft community. The figure compares the effects of extended UV on irradiated and unirradiated GaAs solar cells with INTELSAT-6 Si cells. The effect and its generality, the extent of and conditions for photo-recovery, and the implications of such recovery for missions in radiation environments have not yet been determined.

Meulenberg, Andrew

1995-01-01

361

Radiance And Irradiance Of The Solar HeII 304 Emission Line  

NASA Astrophysics Data System (ADS)

For over 17 years, EIT and the later EUVI instruments aboard SoHO and STEREO, respectively, have provided a time series of radiant images in the HeII 30.4 nm transition region and three coronal emission lines (FeIX/X, FeXII, and FeXV). While the EIT measurements were gathered from positions approximately on the Earth-Sun axis, EUVI images have been gathered at angles ranging to more than ×90 degrees in solar longitude relative the Earth-Sun axis. Using a Differential Emission Measure (DEM) model, these measurements provide a basis for estimates of the spectral irradiance for the solar spectrum of wavelengths between 15 and 50 nm at any position in the heliosphere. In particular, we generate the He 30.4 spectral irradiance in all directions in the heliosphere and examine its time series in selected directions. Such spectra are utilized for two distinct purposes. First, the photoionization rate of neutral He at each position is calculated. Neutral He is of interest because it traverses the heliopause relatively undisturbed and therefore provides a measure of isotopic parameters beyond the heliosphere. Second, we use these generate a time series of estimates of the solar spectral luminosity in the HeII 30.4 nm emission line extending from the recent past solar cycle 23 minimum into the current weak solar cycle 24 enabling an estimate of its variation over the solar cycle. Because this 30.4~nm spectral luminosity is the sum of such radiation in all directions, its time series is devoid of the 27-day solar rotation periodicity present in indices typically used to represent solar activity.

McMullin, D. R.; Floyd, L. E.; Auchère, F.

2013-12-01

362

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

NASA Astrophysics Data System (ADS)

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 measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments.

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

363

Solar Irradiance Reference Spectra (SIRS) for IHY2007 Whole Heliosphere Interval (WHI)  

NASA Astrophysics Data System (ADS)

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/.

Woods, T.; Chamberlin, P.; Snow, M.; Harder, J.

2008-12-01

364

Spiritualists, Aliens and UFOs: Extraterrestrials as spirit guides  

Microsoft Academic Search

One of the most striking innovations within contemporary North American Spiritualism is the adoption of extraterrestrials as spirit guides by some contemporary Spiritualists. It is here that the New Age fascination with extraterrestrials and UFOs has taken on a uniquely Spiritualist form. Extraterrestrials have come to represent for many Spiritualists the successful achievement of the ultimate Spiritualist goal: the union

Jennifer E. Porter

1996-01-01

365

The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.  

NASA Technical Reports Server (NTRS)

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).

Ghosh, S.; Sargent, G. A.

1972-01-01

366

Proton irradiation environment of solar system objects in the heliospheric boundary regions  

NASA Astrophysics Data System (ADS)

Two classes of outer solar system objects, Scattered Disk Objects and comets, include many known members that are natural counterparts of the Voyager 1 spacecraft now traversing the heliosheath enroute to the heliopause. Thirty-two Scattered Disk Objects and about ten times more comets, as cataloged by the Smithsonian Astrophysical Observatory's Minor Planets Center, have orbits passing partly or wholly through the heliosheath. Objects passing from the supersonic heliosphere, upstream of the solar wind termination shock, through the heliosheath and out into the local interstellar medium may undergo increasing surface irradiation intensities as suggested by Voyager 1 measurements and limits on interstellar proton flux spectra. Correspondingly, volume dosage rates for chemically significant surface irradiation at micron to meter depths could also increase with potential cumulative effects on surface composition, albedo, and atmospheric evolution of these objects.

Cooper, John F.; Hill, Matthew E.; Richardson, John D.; Sturner, Steven J.

2006-09-01

367

Intra-hour Direct Normal Irradiance Solar Forecasting Using Genetic Programming  

NASA Astrophysics Data System (ADS)

The development and utilization of solar energy has resulted in increased interest in solar irradiance forecasting. Ground level insolation has a natural variability due to atmospheric processes that are directly tied to the local meteorological conditions. Independent System Operators (ISOs) find that forecasting errors for small timescales are highly dependent on the characteristics and dynamics of the local cloud cover. This work seeks to explore the use of Genetic Programming to develop forecasting programs that surpass the performance of persistence forecasting. Specifically, our interest lies in forecasting a 30-second average Direct Normal Irradiance with a time horizon of five minutes. The GP-produced forecasting programs will be compared to the performance of persistence forecasting in the terms of Root Means-Squared Errors (RMSE). These proof-of-concept experiments have demonstrated that GP is a promising approach, producing forecasting programs with a 10% performance improvement over persistence forecasts.

Queener, Benjamin Daniel

368

The inference of Spectral Solar Irradiance from equatorial stratospheric ozone and current limitations of our knowledge  

NASA Astrophysics Data System (ADS)

Absorption of solar ultraviolet (UV) radiation by ozone is the main source of heating in the stratosphere. Variations in solar UV modify the ozone concentration and heating rates leading to dynamical feedbacks throughout the middle and lower atmosphere. The magnitude of spectral solar irradiance (SSI) cycle changes is still not well constrained and, therefore, the effect of solar variability on the Earth's climate system is also uncertain. Observations from the SORCE mission suggest much larger solar cycle UV variations compared to SSI models based on earlier missions. Some investigations employing SORCE and modelled SSI data in atmospheric models show similar ozone trends over the solar cycle to observed ozone profiles. However, estimates are hampered by the large uncertainties in the measurement of variability in both SSI and ozone. We combine SSI and ozone observations in an attempt to better determine variations in both, using a Bayesian formalism that considers the uncertainties in measured SC ozone profiles and SSI SC changes. We do this by showing that the tropical stratospheric ozone response to changes in solar UV irradiance can be well-approximated by the summation of independent ozone profiles that result from linear SSI changes in six wavelength bands between 176 and 310 nm. Our results indicate that using current estimates of ozone change profiles it is not possible to distinguish between different SSI datasets. In principle, it would be possible to constrain the SSI changes, but only by reducing the large uncertainty current in both ozone and SSI datasets, or by including additional constraints such as temperature or other chemical components.

Ball, William; Haigh, Joanna; Mortlock, Daniel; Egerton, Jack

2014-05-01

369

UV Radiation, Vitamin D and Human Health: An Unfolding Controversy Comparisons of Estimated Economic Burdens due to Insufficient Solar Ultraviolet Irradiance and Vitamin D and Excess Solar UV Irradiance for the United States  

Microsoft Academic Search

Vitamin D sufficiency is required for optimal health, and solar ultraviolet B (UVB) irradiance is an important source of vitamin D. UVB and\\/or vitamin D have been found in observational studies to be associated with reduced risk for over a dozen forms of cancer, multiple sclerosis, osteoporotic fractures, and several other diseases. On the other hand, excess UV irradiance is

William B. Grant; Cedric F. Garland; Michael F. Holick

370

Long-term patterns of solar irradiance forcing in model experiments and proxy based surface temperature reconstructions  

Microsoft Academic Search

Comparisons are made of long-term empirical and model-estimated patterns of solar irradiance forcing during a 200-year period (1650-1850), which precedes any apparent anthropogenic influence on climate. This interval encompasses a considerable range (approxi- mately 4 W\\/m2) of estimated variation in solar output, including the ''Maunder'' and ''Dalton'' Minima of so- lar irradiance, and an intervening interval of relatively high values

A. M. Waple; R. S. Bradley; M. E. Mann

2002-01-01

371

p53 induction in normal human skin in vitro following exposure to solar simulated UV and UV-B irradiation  

Microsoft Academic Search

Exposure of normal human breast skin ex vivo to physiological levels of UV-B and solar simulated UV results in a UV dose- and time-dependent increase in epidermal p53, as determined by PAGE analysis. Peak p53 levels are detected 12 to 24 h post irradiation with UV-B (470–1410 mJ cm?2) and solar simulated UV (5–12 minimal erythema dose (MED) equivalents). Irradiation

Victoria Davenport; Jenny F. Morris; Reza Motazed; Anthony C. Chu

1999-01-01

372

Analysis of Anomalous Degradation of Cu(In,Ga)Se2 Thin-Film Solar Cells Irradiated with Protons  

Microsoft Academic Search

We analyzed the radiation response of Cu(In,Ga)Se2 (CIGS) solar cells to high-fluence protons. An in situ measurement system was constructed to measure the electrical performance of the CIGS solar cells immediately after proton irradiation. Using this system, abrupt degradation of Isc in the cells irradiated with 0.38 MeV protons at room temperature was observed, which was caused by a decrease

Shirou Kawakita; Mitsuru Imaizumi; Koichi Kibe; Takeshi Ohshima; Hisayoshi Itoh; Shinichi Yoda; Osamu Odawara

2007-01-01

373

Three Decades of Total Solar Irradiance Monitoring and resolution of the 'ACRIM-gap' dilemma  

Microsoft Academic Search

Total solar irradiance (TSI) of the Earth has been monitored for three decades (1978 - 2008) by a series of contiguous, overlapping satellite experiments: Nimbus7\\/ERB, SMM\\/ACRIM1, ERBS\\/ERBE, UARS\\/ACRIM2, SOHO\\/VIRGO, ACRIMSAT\\/ACRIM3 and SORCE\\/TIM. The accuracy and precision of TSI results varies between experiments but the end-to-end traceability (relative precision) of the ACRIM composite time series constructed from the 30 year database

R. C. Willson

2008-01-01

374

An estimation of the surface solar ultraviolet irradiance during an extreme total ozone minimum  

Microsoft Academic Search

Summary A simple theoretical algorithm has been employed to estimate the solar ultraviolet irradiance at Athens, Greece (38.7°N, 23.4°E) during, summertime 1993, a year of extreme total ozone minimum in the existing data record. This estimation has been performed by using total ozone measurements as derived by both ground-based and satellite instrumentation. The utilization of the present investigation will assist

M. Efstathiou; C. Varotsos; K. Ya. Kondratyev

1998-01-01

375

The Delta-Sobolev Approach for Modeling Solar Spectral Irradiance and Radiance  

Microsoft Academic Search

This dissertation reports the development and evaluation of a solar radiation model, which gives irradiance and radiance results at the bottom and top of an atmosphere of specified optical depth for each of 145 spectral intervals from 0.29 to 4.05 mum. Absorption by water vapor, aerosols, ozone and uniformly mixed gases; scattering by molecules and aerosols; and non-Lambertian surface reflectance

Xuwu Xiang; Xuwu

1990-01-01

376

Study of thin-film silicon solar cells at irradiances above ten thousand suns  

Microsoft Academic Search

We used a tightly focused Gaussian beam of a HeNe laser to study accelerated light-induced degradation (Staebler-Wronski effect) and high photocarrier generation rates in amorphous and microcrystalline silicon thin-film solar cells, at up to13 MW\\/m2 irradiance. For the experiments, the spot radius was varied from a minimum of 8.6 mum in the focus to around 1 mm away from the

Yeping Lu; Amin Abdolvand; Steve Reynolds

2010-01-01

377

Nonisothermal nongray absorbing-emitting-scattering suspension of FeâOâ particles under concentrated solar irradiation  

Microsoft Academic Search

Radiation transfer within a cloud of magnetite (FeâOâ) particles contained in an infinite slab is considered. The particulate cloud is modeled as a pseudo-continuous, nongray, nonisothermal, absorbing, emitting, and anisotropically scattering medium. The energy source is concentrated solar irradiation, which is assumed to be diffusely and uniformly distributed over a circular opening and has a 5780 K blackbody spectrum. Mie-scattering

D. Mischler; A. Steinfeld

1995-01-01

378

Improved broadband solar irradiance from the multi-filter rotating shadowband radiometer  

Microsoft Academic Search

Approximations to total and diffuse horizontal and direct normal, broadband solar irradiance (280-4000 nm) can be obtained from the multi-filter rotating shadowband radiometer (MFRSR) using the unfiltered silicon channel of this seven-channel instrument. However, the unfiltered silicon channel only responds to wavelengths between 300 and 1100 nm and does not have a uniform spectral response. In contrast, the best, more

J. J. Michalsky; J. A. Augustine; P. W. Kiedron

2009-01-01

379

Improved broadband solar irradiance from the multi-filter rotating shadowband radiometer  

Microsoft Academic Search

Approximations to total and diffuse horizontal and direct normal, broadband solar irradiance (280–4000nm) can be obtained from the multi-filter rotating shadowband radiometer (MFRSR) using the unfiltered silicon channel of this seven-channel instrument. However, the unfiltered silicon channel only responds to wavelengths between 300 and 1100nm and does not have a uniform spectral response. In contrast, the best, more expensive, first-class,

J. J. Michalsky; J. A. Augustine; P. W. Kiedron

2009-01-01

380

An investigation of the energy balance of solar active regions using the ACRIM irradiance data  

NASA Technical Reports Server (NTRS)

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.

Petro, L. D.

1986-01-01

381

Ion irradiation: its relevance to the evolution of complex organics in the outer solar system.  

PubMed

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

Strazzulla, G

1997-01-01

382

Response of the upper atmosphere to variations in the solar soft x-ray irradiance. Ph.D. Thesis  

SciTech Connect

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 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.

Bailey, S.M.

1995-01-01

383

Response of the upper atmosphere to variations in the solar soft x-ray irradiance. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

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.

Bailey, Scott Martin

1995-01-01

384

A model to determine soft X-ray fluxes of solar flares - A contribution to ISO Standard Determining Solar Irradiances  

NASA Astrophysics Data System (ADS)

A model of solar flare soft X-ray fluxes is proposed as a part of ISO standard for determining solar irradiances (WD21348). The model gives values of X-ray fluxes in 13 narrow spectral intervals (from 0.1 to 10 nm), with their wavelengths adjusted for convenience of aeronomic model calculations. The model was developed as a result of data processing of more than 200 flares measured on the SOLRAD satellites and rockets. The model is presented in a convenient simple analytical form, which does not practically demand any computing facilities. An input parameter for the model was a value of soft X-ray flux in the 1 8 nm wave-range. These fluxes have been- measured for a long time as a constituent part of solar patrol. Calibration of the model was performed with using ionospheric vertical sounding data of E- region as a natural spectral-selective detector of solar radiation and then was verified with using the latest measurements data sets.

Nusinov, A.; Chulankin, D.

385

Comparison of Total Solar Irradiance with NASA/NSO Spectromagnetograph Data in Solar Cycles 22 and 23  

NASA Technical Reports Server (NTRS)

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.

Jones, Harrison P.; Branston, Detrick D.; Jones, Patricia B.; Popescu, Miruna D.

2002-01-01

386

Contribution of Solar Chromospheric Fine Scale Features to UV Irradiance Variability  

NASA Astrophysics Data System (ADS)

The Sun is the primary source of energy responsible for governing both the weather and climate of Earth. For that reason alone one would expect that changes in the amount and type of energy Earth received from the Sun could alter weather and climate on the Earth. The variations in the UV irradiance are produced by surface manifestation of solar magnetic activity. Considering the variations in the solar UV flux may cause significant changes in the Earth’s climate, understanding the physical origin of UV irradiance changes is an extremely important issue in Solar and Space Physics. We have segregated the (i) plages, (ii) magnetic network, and (iii) intranetwork + the background regions from the Call K spectroheliograms of 1980 and 1992, observed at the National Solar Observatory at Sacramento Peak, using their histograms taken for the full-disk. The different parameters like the intensity and area of the chromospheric features, the full-disk intensity (spatial K index), and the full width at half maximum (FWHM) of the histograms have been derived from the images. The spatial K index, FWHM, and the intensity of various features have been compared to the UV irradiance measured in the Mgll h and k lines by the Nimbus7 and NOAA9 satellites and it has been found that they are correlated with the Mgll h and k c/w ratio. We established, for the first time, from the results of 1992 images and of 1980 that the FWHM can be used as a good index for measuring and describing the chromospheric activity in the K-line. The results of both 1980 and 1992 images show an anticorrelation between the intensity and area of the network elements, which confirm the earlier findings derived entirely from different data set from Kodaikanal Call K spectroheliograms analyzed for the center of the solar disc in a quiet regions for a longer time interval of 1951 to 1983 (Kariyappa and Sivaraman, 1994). During solar minimum the network is fainter but covers a larger area than during solar maximum. These results suggest that the variations in both the intensity and area of the various chromospheric features have to be taken into account in irradiance models.

Kariyappa, R.

2006-11-01

387

Narrowband filter radiometer for ground-based measurements of global ultraviolet solar irradiance and total ozone.  

PubMed

The ultraviolet narrowband filter radiometer (UV-RAD) designed by the authors to take ground-based measurements of UV solar irradiance, total ozone, and biological dose rate is described, together with the main characteristics of the seven blocked filters mounted on it, all of which have full widths at half maxima that range 0.67 to 0.98 nm. We have analyzed the causes of cosine response and calibration errors carefully to define the corresponding correction terms, paying particular attention to those that are due to the spectral displacements of the filter transmittance peaks from the integer wavelength values. The influence of the ozone profile on the retrieved ozone at large solar zenith angles has also been examined by means of field measurements. The opportunity of carrying out nearly monochromatic irradiance measurements offered by the UV-RAD allowed us to improve the procedure usually followed to reconstruct the solar spectrum at the surface by fitting the computed results, using radiative transfer models with field measurements of irradiance. Two long-term comparison campaigns took place, showing that a mean discrepancy of +0.3% exists between the UV-RAD total ozone values and those given by the Brewer #63 spectroradiometer and that mean differences of +0.3% and -0.9% exist between the erythemal dose rates determined with the UV-RAD and those obtained with the Brewer #63 and the Brewer #104 spectroradiometers, respectively. PMID:16778947

Petkov, Boyan; Vitale, Vito; Tomasi, Claudio; Bonafé, Ubaldo; Scaglione, Salvatore; Flori, Daniele; Santaguida, Riccardo; Gausa, Michael; Hansen, Georg; Colombo, Tiziano

2006-06-20

388

Narrowband filter radiometer for ground-based measurements of global ultraviolet solar irradiance and total ozone  

NASA Astrophysics Data System (ADS)

The ultraviolet narrowband filter radiometer (UV-RAD) designed by the authors to take ground-based measurements of UV solar irradiance, total ozone, and biological dose rate is described, together with the main characteristics of the seven blocked filters mounted on it, all of which have full widths at half maxima that range 0.67 to 0.98 nm. We have analyzed the causes of cosine response and calibration errors carefully to define the corresponding correction terms, paying particular attention to those that are due to the spectral displacements of the filter transmittance peaks from the integer wavelength values. The influence of the ozone profile on the retrieved ozone at large solar zenith angles has also been examined by means of field measurements. The opportunity of carrying out nearly monochromatic irradiance measurements offered by the UV-RAD allowed us to improve the procedure usually followed to reconstruct the solar spectrum at the surface by fitting the computed results, using radiative transfer models with field measurements of irradiance. Two long-term comparison campaigns took place, showing that a mean discrepancy of +0.3% exists between the UV-RAD total ozone values and those given by the Brewer #63 spectroradiometer and that mean differences of +0.3% and -0.9% exist between the erythemal dose rates determined with the UV-RAD and those obtained with the Brewer #63 and the Brewer #104 spectroradiometers, respectively.

Petkov, Boyan; Vitale, Vito; Tomasi, Claudio; Bonafé, Ubaldo; Scaglione, Salvatore; Flori, Daniele; Santaguida, Riccardo; Gausa, Michael; Hansen, Georg; Colombo, Tiziano

2006-06-01

389

Local overbrightness of the solar irradiance on the ground generated by cirrus.  

NASA Astrophysics Data System (ADS)

Gérard Thuillier1, Jean-Marie Perrin2, Philippe Keckhut1, Julien Jumelet1, Nadège Montoux1, Slimane Bekki1, and François Huppert2 (1) Service d'Aéronomie du CNRS, (2) Observatoire de Haute Provence At Observatoire de Haute Provence, a set of instruments has been installed for providing measurements characterising the troposphere properties as the solar spectral irradiance on the ground, water (solid, liquid, or gaseous), aerosols, minor constituents such as ozone. These instruments are lidars, pyranometers (total and UVB), a daytime all sky camera, and a sunspectrometer. A study is presented concerning the influence of the cirrus on the solar irradiance budget on the ground. Comparison between pyranometers data and predictions by modelling based on radiative transfer processes, shows cases of overbrightness occurring in total and UVB solar irradiance on the ground, which are linked to the presence of cirrus as revealed by the daytime all sky camera images. However it exits also cases for which overbrightness in UVB does not occur. To understand the above observations, we have developed a model of scattering within a cirrus cloud. To explain the absence of overbrightness in UVB, it is necessary to include a carbonaceous core inside ice aerosols.

Thuillier, G.

2009-04-01

390

Correlation of electron and proton irradiation-induced damage in InP solar cells  

NASA Technical Reports Server (NTRS)

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.

Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

1995-01-01

391

Optical and Solar Cell Properties of Alpha-ray, Proton, and Gamma-ray Irradiated Cu(In,Ga)Se2 Thin Films and Solar Cells  

NASA Astrophysics Data System (ADS)

The effects of alpha-ray, proton, and gamma-ray irradiation on the electrical properties of Cu(In,Ga)Se2 (CIGS) solar cells and the photoluminescence spectra of CIGS and CuInSe2 (CIS) thin films were investigated. Particle irradiation using alpha-ray and proton primarily degraded the interfaces of CIGS solar cells, even though the CIS and CIGS thin films did not degraded, in the case of a low irradiation fluence of the order of 109 cm-2. On the other hand, CIS and CIGS showed good tolerance to gamma-ray irradiation because the impact of wave radiation is insufficient to degrade the crystal, in comparison with particle radiation. These results will become the first step toward realizing practical applications of CIGS solar cells in space and clarifying their degradation mechanism.

Mutsumi Sugiyama,; Toshihiro Yasuniwa,; Hisayuki Nakanishi,; Shigefusa F. Chichibu,; Shinichi Kimura,

2010-04-01

392

Correlation of electron and proton irradiation-induced damage in InP solar cells  

NASA Technical Reports Server (NTRS)

The measured degradation of epitaxial shallow homojunction n(+)/p InP solar cells under 1 MeV electron irradiation is correlated with that measured under 3 MeV proton irradiation based on 'displacement damage dose'. The measured data is analyzed as a function of displacement damage dose from which an electron to proton dose equivalency ratio is determined which enables the electron and proton degradation data to be described by a single degradation curve. It is discussed how this single curve can be used to predict the cell degradation under irradiation by any particle energy. The degradation curve is used to compare the radiation response of InP and GaAs/Ge cells on an absolute damage energy scale. The comparison shows InP to be inherently more resistant to displacement damage deposition than the GaAs/Ge.

Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

1996-01-01

393

Effect of electron irradiation in vacuum on FEP-A silicon solar cell covers  

NASA Technical Reports Server (NTRS)

Fluorinated ethylene-propylene-A (FEP-A) covers on silicon solar cells were irradiated with 1-MeV electrons, in vacuum, to an accumulated fluence equivalent to approximately 28 years in synchronous orbit. The effect of irradiation on the light transmittance of FEP-A was checked by measuring the short-circuit current of the cells after each dose increment. The results indicate no apparent overall loss in transmission due to irradiation of FEP-A. Filter wheel measurements revealed some darkening of the FEP-A at the blue end of the spectrum. Although no delamination from the cell surface was observed while in vacuum, embrittlement of FEP-A occurred at the accumulated dose.

Marsik, S. J.; Broder, J. D.

1975-01-01

394

Solar Ultraviolet Irradiation Induces Decorin Degradation in Human Skin Likely via Neutrophil Elastase  

PubMed Central

Exposure of human skin to solar ultraviolet (UV) irradiation induces matrix metalloproteinase-1 (MMP-1) activity, which degrades type I collagen fibrils. Type I collagen is the most abundant protein in skin and constitutes the majority of skin connective tissue (dermis). Degradation of collagen fibrils impairs the structure and function of skin that characterize skin aging. Decorin is the predominant proteoglycan in human dermis. In model systems, decorin binds to and protects type I collagen fibrils from proteolytic degradation by enzymes such as MMP-1. Little is known regarding alterations of decorin in response to UV irradiation. We found that solar-simulated UV irradiation of human skin in vivo stimulated substantial decorin degradation, with kinetics similar to infiltration of polymorphonuclear (PMN) cells. Proteases that were released from isolated PMN cells degraded decorin in vitro. A highly selective inhibitor of neutrophil elastase blocked decorin breakdown by proteases released from PMN cells. Furthermore, purified neutrophil elastase cleaved decorin in vitro and generated fragments with similar molecular weights as those resulting from protease activity released from PMN cells, and as observed in UV-irradiated human skin. Cleavage of decorin by neutrophil elastase significantly augmented fragmentation of type I collagen fibrils by MMP-1. Taken together, these data indicate that PMN cell proteases, especially neutrophil elastase, degrade decorin, and this degradation renders collagen fibrils more susceptible to MMP-1 cleavage. These data identify decorin degradation and neutrophil elastase as potential therapeutic targets for mitigating sun exposure-induced collagen fibril degradation in human skin.

Liu, Ying; Remmer, Henriette A.; Voorhees, John; Fisher, Gary J.

2013-01-01

395

Implications of measured differences in the spectroradiometric sensitivity of SBUV\\/2 instruments in air and vacuum on long-term measurements of stratospheric ozone and solar irradiance variations  

Microsoft Academic Search

In recent years, the consistency of ultraviolet solar spectral irradiance measurements has improved to the extent that broad band averages of solar irradiances agree to within a few percent over ranges of a few hundred nanometers. Over spectral ranges from tens to tenths of nanometers significantly larger disagreements in spectral irradiances are observed. Some well known factors which contribute to

William K. Fowler; Kevin W. Kelly; Donald F. Heath

1996-01-01

396

The Variation of the Solar Diameter and Irradiance:. Eclipse Observation of July 11, 2010  

NASA Astrophysics Data System (ADS)

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.

Koutchmy, Serge; Bazin, Cyril; Prado, Jean-Yves; Lamy, Philippe; Rocher, Patrick

2013-03-01

397

Total Solar Irradiance during the past 9300 Years inferred from the Cosmogenic Radionuclide Beryllium-10  

NASA Astrophysics Data System (ADS)

The Sun is the main source of energy for the Earth. There is growing evidence that climate changes in the past coincide with changes in solar activity. This raises the question about the Sun’s role in past, present, and future global change. To answer this question, the total solar irradiance (TSI) has to be known not only for the present period of high solar activity, but also for periods when the Sun was very quiet, such as the Maunder Minimum (1645-1715). Direct instrumental data of TSI goes only back to 1978. We present the first reconstruction of TSI covering the past 9300 years. It is based on a recently derived relationship between observed TSI and the open solar magnetic field. The open solar magnetic field can be obtained from the cosmogenic radionuclide Beryllium-10 measured in ice cores. Thus, Beryllium-10 allows reconstructing TSI much further back than the existing record of sunspots, which is often used as a proxy. The resulting increase in the average TSI from the Maunder Minimum to the present amounts to (0.9±0.4)Wm-2 corresponding to a global radiative forcing of (0.16±0.07)Wm-2. This change is smaller than previous TSI reconstructions commonly used in climate studies. In combination with climate models, our reconstruction offers the possibility to quantitatively test the claimed links between solar forcing and climate change.

Steinhilber, F.; Beer, J.; Frohlich, C.

2009-12-01

398

On the improbability of intelligent extraterrestrials  

Microsoft Academic Search

Discussions relating to the prevalence of extraterrestrial life generally remain ambiguous due to the lack of a suitable model for the development of biology. In this paper a simple model is proposed based on neutral evolution theory which leads to quantitative values for the genome growth rate within a biosphere. It is hypothesised that the genome size is a measure

A. Bond

1982-01-01

399

Conway Morris: Extraterrestrials: Aliens like us?  

NASA Astrophysics Data System (ADS)

So what are they going to be like, those long-expected extraterrestrials? Hideous hydrocarbon arachnoids, waving laser cannons as they chase screaming humans, repulsively surveying the scene through empathy-free compound eyes? Or maybe laughing bipeds, chatting away, holding a glass of wine, a bit like us?

Morris, Simon Conway

2005-08-01

400

SETI [Search for ExtraTerrestrial Intelligence  

Microsoft Academic Search

Some critics of the Search for Extra-Terrestrial Intelligence (SETI) like to bolster their arguments with what they call the Fermi Paradox. Legend has it that one day at Los Alamos, shortly after the Alamogordo test (when the first atomic bomb was exploded in the desert about 50 miles northwest of this town on July 16, 1945), Enrico Fermi abruptly broke

B. M. Oliver

1994-01-01