These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

2

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

3

Extraterrestrials  

NASA Astrophysics Data System (ADS)

1. An explanation for the absence of extraterrestrials on Earth Michael H. Hart; 2. One attempt to find where they are: NASA's high resolution microwave survey Jill Tarter; 3. An examination of claims that extraterrestrial visitors to Earth are being observed Robert Sheaffer; 4. The likelihood of interstellar colonization, and the absence of its evidence Sebastian von Hoerner; 5. Preemption of the galaxy by the first advanced civilization Ronald Bracewell; 6. Stellar evolution: motivation for the mass interstellar migrations Ben Zuckerman; 7. Interstellar propulsion systems Freeman Dyson; 8. Interstellar travel: a review Ian A. Crawford; 9. Settlements in space, and interstellar travel Cliff Singer; 10. Terraforming James Oberg; 11. Estimates of expansion time scales Eric M. Jones; 12. A search for tritium sources in our Solar System may reveal the presence of space-probes from other stellar systems Michael D. Papagiannis; 13. Primordial organic cosmochemistry Cyril Ponnamperuma and Rafael Navarro-Gonzalez; 14. Chance and the origin of life Edward Argyle; 15. The RNA world: life before DNA and protein Gerald F. Joyce; 16. The search for extraterrestrial intelligence Ernst Nayr; 17. Alone in a crowded universe Jared Diamond; 18. Possible forms of life in environments very different from the Earth Robert Shapiro and Gerald Feinberg; 19. Cosmological SETI frequency standards J. Richard Gott, III; 20. Galactic chemical evolution: implications for the existence of habitable planets Virginia Trimble; 21. The frequency of planetary systems in the galaxy Jonathan I. Lunine; 22. Atmospheric evolution, the Drake equation, and DNA: sparse life in an infinite universe Michael H. Hart.

Zuckerman, Ben; Hart, Michael H.

1995-09-01

4

Solar spectral irradiance at ground level  

NASA Technical Reports Server (NTRS)

Available quantitative data on solar total and spectral irradiance is examined in the context of utilization of solar irradiance for terrestrial applications of solar energy. A brief review is given on the extraterrestrial solar total and spectral irradiance values. Computed values of solar spectral irradiance at ground level for different air mass values and various levels of atmospheric pollution or turbidity are also 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 from air mass two solar spectral irradiance for the four degrees of atmospheric pollution. Total solar spectral irradiance measured with a prism monochromator is examined to evaluate the direct solar spectral irradiance for a surface normal to the sun's rays and to compare the computed spectrum with the experimentally observed one.

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

1978-01-01

5

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

6

A high-resolution extraterrestrial solar spectrum and water vapour continuum at near infrared wavelengths from ground-based spectrometer measurements  

NASA Astrophysics Data System (ADS)

A high resolution extraterrestrial solar spectrum (CAVIAR solar spectrum) and water vapour continuum have been derived in near infrared windows from 2000-10000 cm-1 (105?m), by applying the Langley technique to calibrated ground-based high-resolution Fourier transform spectrometer measurements, made under clear-sky conditions. The effect of the choice of an extraterrestrial solar spectrum for radiative transfer calculations of clear-sky absorption and heating rates in the near infrared was also studied. There is a good agreement between the solar lines strengths and positions of the CAVIAR solar spectrum and those from both high-resolution satellite and ground-based measurements in their regions of spectral overlap. However, there are significant differences between the structure of the CAVIAR solar spectrum and spectra from models. Many of the detected lines are missing from widely-used modelled extraterrestrial solar spectrum. The absolute level and hence wavenumber-integrated solar irradiance of the CAVIAR solar spectrum was also found to be 8% lower than the satellite-based Thuillier et al spectra from 5200-10000 cm-1. Using different extraterrestrial solar spectra for radiative transfer calculations in the near infrared led to differences of up to about 11 W m-2 (8.2%) in the absorbed solar irradiance while the tropospheric and stratospheric heating rates could respectively differ by up to about 0.13K day-1 (8.1%) and 0.19 K day-1 (7.6%) for an overhead Sun and mid-latitude summer atmosphere. This work has shown that the widely-used empirically modelled continuum may be underestimating the strength of the water vapour continuum from 2000-10000 cm-1, with the derived continuum up to more than 2 orders of magnitude stronger at some wavenumbers in the windows. The derived continuum is also stronger than that implied by laboratory measurements, by a factor of up to 40 in some spectral regions.

Menang, K. P.

7

Laboratory Study of Extraterrestrial Ices Electrical Properties and Interaction with Irradiation  

NASA Astrophysics Data System (ADS)

This dissertation describes experimental efforts intended to investigate various physical and chemical processes relevant to the ice coated objects in the outer solar system and interstellar medium. These cold icy surfaces are constantly bombarded by energetic ions, electrons, UV photons and micrometeorites, which alter the physical and chemical properties of the surfaces. Experimental investigations on laboratory analogs are useful to accurately interpret the astronomical observations. Ultra high vacuum, UV photons/electrons/ions irradiation and low temperature prepared ices are usual ways to simulate the space environment. We present an improved method to better simulate the radiation environment, by maintaining an ambient pressure of relevant molecules during irradiation. This ambient gas mimics the tenuous molecular atmospheres surrounding icy objects, such as the O2 exospheres of Jovian satellites Europa and Ganymede and Saturn's icy Rings and satellite Rhea, formed from sputtering/sublimating of radiolysis and photolysis products near the surface. The coexistence of ambient gas and energetic magnetospheric ion / UV photon irradiation leads to enhanced oxygen adsorption in the nanoporous ice films (T < 70K), due to ion induced pore collapse. The high release temperatures of O2 molecules (T > 140K) helps explain the detected solid O2 on Jovian satellites, Europa, Ganymede and Callisto at surface temperatures high enough to sublime solid O2. Besides, we found that the environment analog leads to new mechanisms in molecule synthesis. Oxygen enrichment due to ion-dissociated ambient O2 results in enhanced H2O2 production, while hydrogen enrichment from UV photon-dissociated H2 within ice+H2 mixtures suppresses the synthesis of H2O 2. These radiation chemical processes may help understanding the origin of detected extraterrestrial molecules. Moreover, we researched on the electrostatic charging/discharging effect of ices due to ion bombardment. Ice films can be charged to a surface potential >200 Volts. Further charging of the ice is limited by the dielectric strength of the ices. The findings help characterizing the surface potential of the icy objects which, if high enough, may reflect low energy magnetospheric ions.

Shi, Jianming

8

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

9

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. PMID:22128323

MacPherson, Glenn J.; Thiemens, Mark H.

2011-01-01

10

Power optimization of an extra-terrestrial, solar-radiant stirling heat engine  

Microsoft Academic Search

The power output and thermal efficiency of a finite-time, optimized, extra-terrestrial, solar-radiant Stirling heat engine have been studied. The thermodynamic model adopted is a regenerative gas Stirling cycle coupled to a heat source and heat sink by radiant heat transfer. Both the heat source and sink are assumed to have infinite heat-capacity rates. Expressions are obtained for optimum power and

David A. Blank; Chih Wu

1995-01-01

11

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

NASA Technical Reports Server (NTRS)

There are two main types of cosmic rays that have sufficient energy to induce nuclear reactions -- the galactic cosmic rays (GCR) and solar cosmic rays (also called solar energetic particles). Both types of particles can have production rates and production ratios in the small objects often found in cold and hot deserts that are different from those seen for most meteorites, which typically have radii of approx.10-100 centimeters. GCR production rates are often lower than those for most meteorites. GCR production ratios, such as Ne-22/Ne-21, are also often different in small objects. Smaller meteoroids also are more likely to have nuclides made by solar-cosmic-ray (SCR) particles than typically-sized meteorites. The very small meteorite Salem had large amounts of SCR-produced radionuclides. Meteorites recovered in Antarctica are more likely to contain SCR-produced nuclides than other meteorites. Martian and lunar meteorites are also likely to have SCR-produced nuclides. Production rates and profiles for SCR-produced nuclides in meteoroids have been calculated previously. However, the cross sections for the nuclear reactions making many SCR-produced nuclides, such as Be-10, were not well measured then. New rates and profiles are calculated here using good cross sections for the reactions making these nuclides.

Reedy, Robert C.

2000-01-01

12

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

NASA Technical Reports Server (NTRS)

There are two main types of cosmic rays that have sufficient energy to induce nuclear reactions -- the galactic cosmic rays (GCR) and solar cosmic rays (also called solar energetic particles). Both types of particles can have production rates and production ratios in the small objects often found in cold and hot deserts that are different from those seen for most meteorites, which typically have radii of approx. 10-100 centimeters. GCR production rates are often lower than those for most meteorites. GCR production ratios, such as Ne-22/Ne-21, are also often different in small objects. Smaller meteoroids also are more likely to have nuclides made by solar-cosmic-ray (SCR) particles than typically-sized meteorites. The very small meteorite Salem had large amounts of SCR-produced radionuclides. Meteorites recovered in Antarctica are more likely to contain SCR-produced nuclides than other meteorites. Martian and lunar meteorites are also likely to have SCR-produced nuclides. Production rates and profiles for SCR-produced nuclides in meteoroids have been calculated previously. However, the cross sections for the nuclear reactions making many SCR-produced nuclides, such as Be-10 were not well measured then. New rates and profiles are calculated here using good cross sections for the reactions making these nuclides.

Reedy, Robert C.

1999-01-01

13

The PUR Experiment on the EXPOSE-R facility: biological dosimetry of solar extraterrestrial UV radiation  

NASA Astrophysics Data System (ADS)

The aim of our experiment Phage and Uracil Response was to extend the use of bacteriophage T7 and uracil biological dosimeters for measuring the biologically effective ultraviolet (UV) dose in the harsh extraterrestrial radiation conditions. The biological detectors were exposed in vacuum-tightly cases in the European Space Agency (ESA) astrobiological exposure facility attached to the external platform of Zvezda (EXPOSE-R). EXPOSE-R took off to the International Space Station (ISS) in November 2008 and was installed on the External platform of the Russian module Zvezda of the ISS in March 2009. Our goal was to determine the dose-effect relation for the formation of photoproducts (i.e. damage to phage DNA and uracil, respectively). The extraterrestrial solar UV radiation ranges over the whole spectrum from vacuum-UV (?<200 nm) to UVA (315 nmextraterrestrial UV radiation. From this aspect the role of the photoreversion in the extension of the biological UV dosimetry are discussed.

Bérces, A.; Egyeki, M.; Fekete, A.; Horneck, G.; Kovács, G.; Panitz, C.

2015-01-01

14

Modeling monthly mean variation of the solar global irradiation  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

15

Absolute spectral measurements of direct solar ultraviolet irradiance with a Brewer spectrophotometer  

NASA Astrophysics Data System (ADS)

A methodology for the absolute calibration of spectral measurements of direct solar ultraviolet radiation, performed with a Brewer spectrophotometer is presented. The method uses absolute measurements of global and diffuse solar irradiance obtained practically simultaneously at each wavelength with the direct-Sun component. On the basis of this calibration, direct-Sun spectra, measured over a wide range of solar zenith angles at a high altitude site, were used to determine the extraterrestrial solar spectrum by applying the Langley extrapolation method. Finally this spectrum is compared with a solar spectrum derived from the airborne tunable laser absorption spectrometer 3 Space Shuttle mission, showing an agreement of better than 3 .

Bais, Alkiviadis F.

1997-07-01

16

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

17

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

18

SIPS: Solar Irradiance Prediction System Stefan Achleitner  

E-print Network

-scaling capacities of renewable energy sources such as wind and solar. However, variability and uncertainty in power potentially limit the impact of fluctuations in solar power generation, specifically in cloudy days when infrastructure using wireless sensor networks (WSNs) to enable sensing of solar irradiance for solar power

Cerpa, Alberto E.

19

Unraveling the chemical history of the Solar System as recorded in extraterrestrial organic matter  

NASA Astrophysics Data System (ADS)

We have initiated an extensive program of molecular analysis of extraterrestrial organic matter isolated from a broad range of meteorites (spanning multiple classes, groups, and petrologic types), including recent molecular spectroscopic analyses of the organic matter in the Comet 81P/Wild 2 samples. The results of these analyses clearly reveal the signature of multiple reaction pathways that transformed extraterrestrial organic matter away from its primitive roots. The most significant molecular transformation occurred in the post-accretionary phase of the parent body. However, each of the various chemical transformation trajectories point unambiguously back to a common primitive origin. Applying a wide range of spectroscopic techniques we find that the primitive organic precursor is striking in its chemical complexity exhibiting a broad array of oxygen- and nitrogen-bearing functional groups. The ?-bonded carbon exists as predominately highly substituted single ring aromatics, there exists no evidence for abundant, large, polycyclic aromatic hydrocarbons (PAHs). We find that the molecular structure of primitive extraterrestrial organics is consistent with synthesis from small reactive molecules, e. g. formaldehyde, whose random condensation and subsequent rearrangement chemistry at low temperatures leads to a highly cross-linked macromolecule.

Cody, George D.; Alexander, Conel M. O'D.; Kilcoyne, A. L. David; Yabuta, Hikaru

2008-10-01

20

Reconstruction of solar UV irradiance since 1974  

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

21

UV solar irradiance low during recent solar minimum  

NASA Astrophysics Data System (ADS)

Solar irradiance, which varies with the 11-year solar cycle and on longer time scales, can affect temperatures and winds in the atmosphere, influencing Earth's climate. As the Sun currently wakes up from a period of low sunspot activity, researchers want to know how irradiance during the recent solar minimum compares to historical levels. In addition to understanding the total received power, it is important to know how various spectral bands behave, in particular, the ultraviolet, which causes heating and winds in the stratosphere. Lockwood analyzed solar ultraviolet spectral irradiance data from May 2003 to August 2005 from both the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) instrument on board the Upper Atmosphere Research Satellite (UARS) and the Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument on the Solar Radiation and Climate Experiment (SORCE) satellite. Using several different methods to intercalibrate the data, he developed a data composite that can be used to determine differences between the recent solar minimum and previous minima. The author found that solar irradiance during the recent sunspot minimum has been especially low. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2010JD014746, 2011)

Balcerak, Ernie

2011-10-01

22

The Sun and Climate Solar Irradiance  

E-print Network

The Sun and Climate #12;Solar Irradiance The Solar Constant f = 1.4 x 106 erg/cm2/s. Over is higher when the Sun is more magnetically active. ·The Sun was magnetically active, and the climate the Sun Drive Climate? #12;The Temperature's Rising #12;Sunspots and CO2 What is Cause and What is Effect

Walter, Frederick M.

23

SOLAR IRRADIANCE FORECASTING FOR THE MANAGEMENT OF SOLAR ENERGY SYSTEMS  

E-print Network

of renewable energy sources into existing energy supply structures. This not only demands substantial efforts. A key issue hereby is the prediction of renewable energy fluxes, typically for time scales from the subSOLAR IRRADIANCE FORECASTING FOR THE MANAGEMENT OF SOLAR ENERGY SYSTEMS Detlev Heinemann Oldenburg

Heinemann, Detlev

24

Nanostructured solar irradiation control materials for solar energy conversion  

NASA Astrophysics Data System (ADS)

Tailoring the solar absorptivity (?s) and thermal emissivity (?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 ?s and ?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 ?s and ?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, Jin Ho; Marshall, Iseley A.; Torrico, Mattew N.; Taylor, Chase R.; Ely, Jeffry; Henderson, Angel; Sauti, Godfrey; Gibbons, Luke J.; Kim, Jae-Woo; Park, Cheol; Lowther, Sharon E.; Lillehei, Peter T.; Bryant, Robert G.

2012-10-01

25

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

26

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

27

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

28

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

29

The Role of Radiation in the Solar Nebula: Correlated Chemistry-Structure- Isotope Studies of Laboratory and Extraterrestrial Organics  

NASA Astrophysics Data System (ADS)

This proposal outlines an interdisciplinary effort aimed at quantitatively evaluating the roles that irradiation played in the evolution of ices and organics in the solar nebula and the potential trapping of noble gases in primitive solids. The collective effort outlined here and in two partnered proposals (PIs Scott Sandford and Fred Ciesla) involves individuals at five primary institutions. We define a series of coordinated experimental, theoretical, and observational projects that are necessary to begin to recognize and understand the complex effects of irradiation in the early Solar System. This coordinated effort is in line with the latest emphasis on interdisciplinary work by the Origins of Solar System program. The specific goal of the CIW-NRL component of the effort is to conduct comparative studies of the isotope composition, chemistry and structure of organic residues from ices subjected to controlled radiation exposures, with those of organic matter in primitive Solar System materials, primarily interplanetary dust particles (IDPs). Three broad tasks will be undertaken: 1) Evaluate the extent to which organic molecules were formed and restructured as they and their icy precursors were irradiated by UV, x-rays and cosmic-rays in the solar nebula. Specifically, we will revisit the model of Ciesla and Sandford (Science, 2012), and evaluate the irradiation doses seen by ices and organics in the disk, as well as the chemical evolution of these species as they move through more realistic disk structures. The detailed consequences of this irradiation, as well as the rates and fluences required to drive changes in chemistry and physical structure, will be determined by complementary experiments and analytic studies. 2) Quantitatively explore the history of noble gases in ices and organics in the outer solar nebula as water ice is desorbed (due to thermal or photo effects) and reformed in the solar nebula. We will also explore how such ices are irradiated and the structural changes that occur in these ices and resulting photo-products. We will determine the extent to which noble gases remain trapped in these ices after processing and in the residues that form from this irradiation, and the extent to which this residue replicates the properties of the enigmatic phase Q carrier of noble gases in meteorites. 3) Determine the isotopic effects of C, H, and N induced by irradiation of ices and organics. We will carry out experiments to determine how enrichments in heavy isotopes may be passed forward from target ices into organics and the extent to which irradiation itself results in isotopic differences between target materials and residues. These results will be combined with dynamical models to determine the range of isotopic ratios expected from irradiative processing in the solar nebula. Each of these experimental and theoretical tasks will be complemented by coordinated microanalytical (chemical-microstructural-isotopic) studies of relevant, naturally- occurring, organic matter in anhydrous chondritic porous IDPs and, if available, ultracarbonaceous micrometeorites. Both are among the most primitive planetary materials available for laboratory study. These observations will be used to better understand the range of properties of early Solar System organic matter and to directly search for evidence of the radiation processing signatures identified by the three major tasks above. Thus, the IDP and micrometeorite analyses are necessary to provide ground-truth for the extensive theoretical and experimental work.

Nittler, Larry

30

Extraterrestrial Communications.  

ERIC Educational Resources Information Center

Discusses the embargo hypothesis--the theory that Earth is apparently free from alien exploitation because of a presumed cosmic quarantine against this planet--which implies that, instead of being only a few hundred years technologically in advance of earthly civilization, extraterrestrials in charge are likely tens of thousands of years in…

Deardorff, James W.

1987-01-01

31

Extraterrestrial Materials: The Role of Synchrotron Radiation Analyses in the Study of our Solar System  

SciTech Connect

Sample-return missions and natural collection processes have provided us with a surprisingly extensive collection of matter from Solar System bodies other than the Earth. These collections include samples from the Moon, Mars, asteroids, interplanetary dust, and, recently, from the Sun (solar wind) and a comet. This presentation will describe some of these materials, how they were collected, and what we have learned from them. Synchrotron radiation analyses of these materials are playing an increasingly valuable role in unraveling the histories and properities of the parent Solar System bodies.

Sutton, Stephen R. [University of Chicago

2006-04-05

32

Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind  

Microsoft Academic Search

Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

R. O. Pepin; R. H. Becker; P. E. Rider

1995-01-01

33

Solar Irradiance and Thermospheric Airglow Rocket Experiments  

NASA Technical Reports Server (NTRS)

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

Solomon, Stanley C.

1998-01-01

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

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

36

Studies of Solar EUV Irradiance from SOHO  

NASA Astrophysics Data System (ADS)

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

2002-06-01

37

Total Solar Irradiance Variability and the Solar Activity Cycle  

E-print Network

It is suggested that the solar variability is due to the perturbed nature of the solar core and this variability is provided by the variability of the solar neutrino flux from the solar neutrino detectors i.e., Homestake, Superkamiokande, SAGE and GALLEX-GNO. The solar neutrino flux in the standard solar model (SSM) was calculated on the assumption of L_nu (neutrino luminosity) = L_gamma (optical luminosity) which implies that if there is a change in optical luminosity then solar neutrino flux data will also be changed. An internal dynamo due to the cyclic variation of nuclear energy generation inside the core of the sun is responsible for the solar activity cycle was suggested and thus the internal magnetic field is also variable. Again the changes in the nuclear energy generation induce structural changes that result in variations of the global solar parameters i.e., luminosity, radius and temperatures etc. From the analysis of total solar irradiance (TSI) data during the year from 1970 to 2003 we have found five phases within the solar activity cycle. The first phase (I) starts before two years from the sunspot minimum. The second phase (II) starts at the time of sunspot minimum and phase (III) starts before 2/3 years from sunspot maximum whereas phase (IV) starts at sunspot maximum and fifth phase (V) starts at after 2-3 years from sunspot maximum.

Probhas Raychaudhuri

2006-05-06

38

Direct solar radiation: spectrum and irradiance derived from sun-photometer measurements.  

PubMed

The continuous spectrum of the direct solar radiation from lambda= 330 to 2690 nm, penetrating a cloudless atmosphere and arriving on the earth surface, is determined by measuring the solar irradiance in ten selected discrete spectral ranges defined by interference filters. Heretofore knowledge of the extraterrestrial solar spectrum has been required as well as of the transmittance functions to describe the spectral optical properties of the atmosphere. A set of appropriate and simple functions is given and discussed, which allows calculation of the molecular, aerosol, oxygen, and ozone optical thicknesses. The influence of atmospheric water vapor is considered through line by line calculations. The dominant and most fluctuating extinction parameters are the aerosol optical thickness and the content of precipitable water vapor. These are obtained by measurements with two sun photometers, developed according to the WMO recommendation. To test the derived solar spectrum at ground level the photometers are also run with nine broadband filters. The values observed differ little from those obtained by integration of the deduced spectral irradiance. Furthermore, the integral value of the resulting entire spectrum agrees reasonably well with the total direct irradiance gained from actinometer measurements. PMID:20531745

Wobrock, W; Eiden, R

1988-06-01

39

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

40

A simple spectral solar irradiance model for cloudless maritime atmospheres  

Microsoft Academic Search

A simple spectral atmospheric radiative transfer model specific for oceanographic applications begins with spectral extraterrestrial solar u-radiance corrected for earth-sun orbital distance. Ir- radiance is then attenuated in passing through the atmosphere by Rayleigh scattering, ozone, oxygen, and water vapor absorption, and marine aerosol scattering and absorption, and is finally reduced by reflectance at the air-sea interface. The model is

WATSON W. GREGG; K. L. CARDER

1990-01-01

41

Solar variability in irradiance and oscillations  

NASA Technical Reports Server (NTRS)

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

Kuhn, Jeff R.

1995-01-01

42

Confronting a solar irradiance reconstruction with solar and stellar data  

NASA Astrophysics Data System (ADS)

Context. A recent paper by Shapiro and colleagues (2011, A&A, 529, A67) reconstructs spectral and total irradiance variations of the Sun during the holocene. Aims. In this note, we comment on why their methodology leads to large (0.5%) variations in the solar TSI on century-long time scales, in stark contrast to other reconstructions which have ˜ 0.1% variations. Methods. We examine the amplitude of the irradiance variations from the point of view of both solar and stellar data. Results. Shapiro et al.'s large amplitudes arise from differences between the irradiances computed from models A and C of Fontenla and colleagues, and from their explicit assumption that the radiances of the quiet Sun vary with the cosmic ray modulation potential. We suggest that the upper photosphere, as given by model A, is too cool, and discuss relative contributions of local vs. global dynamos to the magnetism and irradiance of the quiet Sun. We compare the slow (>22 yr) components of the irradiance reconstructions with secular changes in stellar photometric data that span 20 years or less, and find that the Sun, if varying with such large amplitudes, would still lie within the distribution of stellar photometric variations measured over a 10-20 year period. However, the stellar time series are individually too short to see if the reconstructed variations will remain consistent with stellar variations when observed for several decades more. Conclusions. By adopting model A, Shapiro et al. have over-estimated quiet-Sun irradiance variations by about a factor of two, based upon a re-analysis of sub-mm data from the James Clerk Maxwell telescope. But both estimates are within bounds set by current stellar data. It is therefore vital to continue accurate photometry of solar-like stars for at least another decade, to reveal secular and cyclic variations on multi-decadal time scales of direct interest to the Sun.

Judge, P. G.; Lockwood, G. W.; Radick, R. R.; Henry, G. W.; Shapiro, A. I.; Schmutz, W.; Lindsey, C.

2012-08-01

43

On diamond, graphitic and amorphous carbons in primitive extraterrestrial solar system materials  

NASA Astrophysics Data System (ADS)

Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H) and chaoite. Elemental carbon also occurs as amorphous carbon and poorly graphitized (or turbostratic) carbon but of all the forms of elemental carbon only graphite is stable under physical conditions that prevail in small Solar System bodies and in the interstellar medium. The recent discovery of cubic diamond in carbonaceous chondrites and hexagonal diamond in chondritic interplanetary dust particles (IDPs) have created a renewed interest in the crystalline elemental carbons that were not formed by shock processes on a parent body. Another technique, Raman spectroscopy, confirms a widespread occurrence of disordered graphite in the Allende carbonaceous chondrite and in chondritic IDPs. Elemental carbons have also been identified by their characteristic K-edge features in electron energy loss spectra (EELS). However, the spectroscopic data do not necessarily coincide with those obtained by selected area electron diffraction (SAED). In order to interpret these data in terms of rational crystalline structures, it may be useful to consider the principles underlying electron diffraction and spectroscopic analyses. Electron diffraction depends on electron scattering, on the type of atom and the distance between atoms in a crystal lattice. Spectroscopic data are a function of the type of atom and the energy of bonds between atoms. Also, SAED is a bulk sampling technique when compared to techniques such as Raman spectroscopy or EELS. Thus, it appears that combined analyses provide contradictory results and that amorphous, or short-range ordered, carbon identified by conventional TEM imaging and SAED may show evidence for sp(3) bonds in EELS spectra. It is suggested that complex, nanometer-scale, mineralogical interrelations are common to all elemental carbons irrespective of their origin. The subsequent thermal history, or energy balance, will determine the ultimate microstructure.

Rietmeijer, Frans J. M.

1990-04-01

44

On diamond, graphitic and amorphous carbons in primitive extraterrestrial solar system materials  

NASA Technical Reports Server (NTRS)

Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H) and chaoite. Elemental carbon also occurs as amorphous carbon and poorly graphitized (or turbostratic) carbon but of all the forms of elemental carbon only graphite is stable under physical conditions that prevail in small Solar System bodies and in the interstellar medium. The recent discovery of cubic diamond in carbonaceous chondrites and hexagonal diamond in chondritic interplanetary dust particles (IDPs) have created a renewed interest in the crystalline elemental carbons that were not formed by shock processes on a parent body. Another technique, Raman spectroscopy, confirms a widespread occurrence of disordered graphite in the Allende carbonaceous chondrite and in chondritic IDPs. Elemental carbons have also been identified by their characteristic K-edge features in electron energy loss spectra (EELS). However, the spectroscopic data do not necessarily coincide with those obtained by selected area electron diffraction (SAED). In order to interpret these data in terms of rational crystalline structures, it may be useful to consider the principles underlying electron diffraction and spectroscopic analyses. Electron diffraction depends on electron scattering, on the type of atom and the distance between atoms in a crystal lattice. Spectroscopic data are a function of the type of atom and the energy of bonds between atoms. Also, SAED is a bulk sampling technique when compared to techniques such as Raman spectroscopy or EELS. Thus, it appears that combined analyses provide contradictory results and that amorphous, or short-range ordered, carbon identified by conventional TEM imaging and SAED may show evidence for sp(3) bonds in EELS spectra. It is suggested that complex, nanometer-scale, mineralogical interrelations are common to all elemental carbons irrespective of their origin. The subsequent thermal history, or energy balance, will determine the ultimate microstructure.

Rietmeijer, Frans J. M.

1990-01-01

45

Estimating probability distributions of solar irradiance  

NASA Astrophysics Data System (ADS)

In the presence of clouds the ability to calculate instantaneous spectral irradiance values is limited by the ability to acquire appropriate input parameters for radiative transfer solvers. However, the knowledge of the statistical characteristics of spectral irradiance as a function of season and time of the day is relevant for solar energy and health applications. For this purpose a method to derive the wavelength dependent probability density functions (PDFs) and its seasonal site variability is presented. In contrast to the UVB range, the derived PDFS at three stations in Europe (Bilthoven, Garmisch-Partenkirchen and Thessaloniki) show only minor wavelength dependence above 315 nm. But there are major differences of the PDFs that are attributed to the site specific cloud climatology at these stations. Furthermore the results suggest that the previously described relationship between air mass and bimodality is the consequence of seasonal cloud variations. For Thessaloniki it is shown that the pyranometer sample spread around the cloudless value is proportional to the secant of the solar zenith angle and therefore scales according to air mass. Cloud amount observations are utilized to associate the local maxima of the multimodal PDFs with rough cloudiness states confirming the already established interpretation of broadband data for spectral data as well. As one application example the likelihood of irradiance enhancements over the clear sky case due to clouds is assessed.

Voskrebenzev, A.; Riechelmann, S.; Bais, A.; Slaper, H.; Seckmeyer, G.

2015-02-01

46

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

47

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

48

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

49

Solar Spectral Irradiance Changes During Cycle 24  

NASA Technical Reports Server (NTRS)

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

Marchenko, Sergey; Deland, Matthew

2014-01-01

50

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

51

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

52

COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA IN SOLAR CYCLES 22 AND 23  

E-print Network

and Solar Physics, Southwest Solar Station, c/o National Solar Observatory, 1 P.O. Box 26732, Tucson, AZ 85726; hjones@noao.edu Detrick D. Branston National Solar Observatory, P.O. Box 26732, Tucson, AZ 86726COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA

53

COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA IN SOLAR CYCLES 22 AND 23  

E-print Network

and Solar Physics, Southwest Solar Station, c/o National Solar Observatory,1 P.O. Box 26732, Tucson, AZ 85726; hjones@noao.edu Detrick D. Branston National Solar Observatory, P.O. Box 26732, Tucson, AZ 86726COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA

54

Total solar irradiance monitors, space instruments for measuring total solar irradiance on FY-3 satellites  

NASA Astrophysics Data System (ADS)

Total Solar Irradiance (TSI) has been recorded daily by Total Solar Irradiance Monitors (TSIM) with overlapping measurements on FY-3 (Feng Yun-3) series satellites since 2008. Instrument descriptions, operation in space and flight performance of three TSIMs are presented in this paper. TSI is measured by electrical substitution radiometers integrated in TSIM, with traceability to SI. TSIM/FY-3A and TSIM/FY-3B share nearly the same design. Since TSIM/FY-3A and TSIM/FY-3B have no pointing system, the Sun is only observed when the Sunlight sweeps TSIM's field-of-view and TSI measurements are influenced inevitably by solar pointing errors. TSIM/FY-3C, a radiometer package was constructed with a pointing system for solar tracking in order to achieve accurate solar pointing. TSIM/FY-3C was sent into orbit in September 2013 onboard FY-3C satellite. Daily TSI measurements have been performed by TSIM/FY-3C with autonomous accurate solar tracking for 1 year. TSIM/FY-3C is in a good instrument health according to its on-orbit data.

Wang, Hongrui; Wang, Yupeng; Ye, Xin; Wang, Kai; Yang, Dongjun; Fang, Wei; Li, Huiduan

2014-11-01

55

Extraterrestrial organic analysis.  

NASA Technical Reports Server (NTRS)

Brief review of relevant information on the composition of stars, interstellar matter, and individual bodies of the solar system. An attempt is made to answer fundamental questions of organic cosmochemistry - namely, the nature of the organic and related molecules present in our Galaxy and solar system, the distribution of these molecules in different parts of the two systems, the mechanism of formation of these molecules, and the relation between these molecules and prebiological chemical evolution on the one hand, and terrestrial and, possibly, extraterrestrial biology, on the other. Detailed studies are made of the formation and chemical behavior of the organogenic elements in stars, interstellar matter, comets, meteorites, carbonaceous chondrites, and the terrestrial and Jovian planets.

Oro, J.

1972-01-01

56

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

57

Solar irradiance variations due to active regions  

SciTech Connect

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

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

1982-05-15

58

Modelling rotational and cyclical spectral solar irradiance variations  

NASA Astrophysics Data System (ADS)

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

Unruh, Yvonne

59

Solar total irradiance in cycle 23  

NASA Astrophysics Data System (ADS)

Context. The most recent minimum of solar activity was deeper and longer than the previous two minima as indicated by different proxies of solar activity. This is also true for the total solar irradiance (TSI) according to the PMOD composite. Aims: The apparently unusual behaviour of the TSI has been interpreted as evidence against solar surface magnetism as the main driver of the secular change in the TSI. We test claims that the evolution of the solar surface magnetic field does not reproduce the observed TSI in cycle 23. Methods: We use sensitive, 60-min averaged MDI magnetograms and quasi-simultaneous continuum images as an input to our SATIRE-S model and calculate the TSI variation over cycle 23, sampled roughly every two weeks. The computed TSI is then compared with the PMOD composite of TSI measurements and with the data from two individual instruments, SORCE/TIM and UARS/ACRIM II, that monitored the TSI during the declining phase of cycle 23 and over the previous minimum in 1996, respectively. Results: Excellent agreement is found between the trends shown by the model and almost all sets of measurements. The only exception is the early, i.e. 1996 to 1998, PMOD data. Whereas the agreement between the model and the PMOD composite over the period 1999-2009 is almost perfect, the modelled TSI shows a steeper increase between 1996 and 1999 than implied by the PMOD composite. On the other hand, the steeper trend in the model agrees remarkably well with the ACRIM II data. A closer look at the VIRGO data, which are the basis of the PMOD composite after 1996, reveals that only one of the two VIRGO instruments, the PMO6V, shows the shallower trend present in the composite, whereas the DIARAD measurements indicate a steeper trend. Conclusions: Based on these results, we conclude that (1) the sensitivity changes of the PMO6V radiometers within VIRGO during the first two years have very likely not been correctly evaluated; and that (2) the TSI variations over cycle 23 and the change in the TSI levels between the minima in 1996 and 2008 are consistent with the solar surface magnetism mechanism.

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

2011-05-01

60

Long-term variations in total solar irradiance  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

61

Solar resource assessment with a solar spectral irradiance meter  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

62

Classification of extraterrestrial civilizations  

NASA Astrophysics Data System (ADS)

A scheme of classification of extraterrestrial intelligence (ETI) communities based on the scope of energy accessible to the civilization in question is proposed as an alternative to the Kardeshev (1964) scheme that includes three types of civilization, as determined by their levels of energy expenditure. The proposed scheme includes six classes: (1) a civilization that runs essentially on energy exerted by individual beings or by domesticated lower life forms, (2) harnessing of natural sources on planetary surface with artificial constructions, like water wheels and wind sails, (3) energy from fossils and fissionable isotopes, mined beneath the planet surface, (4) exploitation of nuclear fusion on a large scale, whether on the planet, in space, or from primary solar energy, (5) extensive use of antimatter for energy storage, and (6) energy from spacetime, perhaps via the action of naked singularities.

Tang, Tong B.; Chang, Grace

1991-06-01

63

Extraterrestrial materials processing  

NASA Technical Reports Server (NTRS)

The first year results of a multi-year study of processing extraterrestrial materials for use in space are summarized. Theoretically, there are potential major advantages to be derived from the use of such materials for future space endeavors. The types of known or postulated starting raw materials are described including silicate-rich mixed oxides on the Moon, some asteroids and Mars; free metals in some asteroids and in small quantities in the lunar soil; and probably volatiles like water and CO2 on Mars and some asteroids. Candidate processes for space materials are likely to be significantly different from their terrestrial counterparts largely because of: absence of atmosphere; lack of of readily available working fluids; low- or micro-gravity; no carbon-based fuels; readily available solar energy; and severe constraints on manned intervention. The extraction of metals and oxygen from lunar material by magma electrolysis or by vapor/ion phase separation appears practical.

Steurer, W. H.

1982-01-01

64

Extraterrestrial hydrogeology  

NASA Astrophysics Data System (ADS)

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 precipitation during transient ice- and hot-house conditions, as recorded through the geologic and fossilized records. On the other hand, Mars is mostly in an ice-house stage, which is interrupted by endogenic-driven activity. This activity catastrophically drives short-lived hydrological cycling and associated climatic perturbations. Regional aquifers in the Martian highlands that developed during past, more Earth-like conditions delivered water to the northern plains. Water was also cycled to the South Polar Region during changes in climate induced by endogenic activity and/or by changes in Mars' orbital parameters. Venus very likely had a warm hydrosphere for hundreds of millions of years, before the development of its current extremely hot atmosphere and surface. Subsequently, Venus lost its hydrosphere as solar luminosity increased and a run-away moist greenhouse took effect. Subsurface oceans of water or ammonia-water composition, induced by tidal forces and radiogenic heating, probably occur on the larger satellites Europa, Ganymede, Callisto, Titan, and Triton. Tidal forces operating between some of the small bodies of the outer solar system could also promote the fusion of ice and the stability of inner liquid-water oceans. Les processus de subsurface impliquant l'eau sont communs pour les corps planétaires du système solaire et sont très probables sur les exoplanètes (planètes en dehors du système solaire). Pour plusieurs objets du systèmes solaire, l'eau de subsurface est présente sous forme de glace. Pour la Terre et Mars, les zones saturées de subsurface apparaissent à travers toute leur histoire planétaire. La Terre est particulièrement clémente avec la recharge des réservoirs, avec de amples précipitations, des conditions glaciaires et de fortes chaleurs, comme l'atteste les enregistrements géologiques et paléontologiques. D'un autre côté, Mars se trouve dans une phase essentiellement glaciaire, qui est interrompue par des activités contraintes par les phénomènes endogéniques. Cette activité conduit de manière catastrophique à des cycles hydrologiques et à des perturbations climatiques brutaux. Les aquifères régionaux dans les haute terres martiennes qui se sont formés dans des conditions similaires aux conditions terrestres, alimentent les plaines du Nord. L'eau a également été déplacée vers le Pôle Sud martien durant des changements marqués par une forte activité endogénique et une modification des paramètres de l'orbite de Mars. Venus possèdait vrais emblablement une hydrosphère chaude durant des millions d'année, avant le développement de son atmosphère et sa surface particulièrement chaude. Par après Venus a perdit son hydrosphère alors que la luminosité solaire augmentait et qu'une humidité liée à un effet de serre s'installait. Les océans de subsurface d'eau ou d'eau ammoniacale, induits par les forces de marée et le chauffage radiogénique, apparaissent probablement sur les satellites les plus importants (Europa, Ganymede, Callisto, Titan, Triton). Les forces de marée entre les petits corps externes du système solaire peuvent également occasionner la fusion de glace et la stabilité des océans internes d'eau liquide. Los procesos hídricos subsuperficiales son comunes en cuerpos planetarios del sistema solar y son altamente probables para exoplanetas (planetas fuera del sistema solar). Para muchos cuerpos del sistema solar, el agua subsuperficial existe como hielo. Para la Tierra y Marte han ocurrido zonas saturadas subsuperficiales a través de sus historias planetarias. La Tierra es principalmente generosa con la recarga de la mayoría de rese

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

2005-03-01

65

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

66

Modelling total solar irradiance using a flux transport model  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

67

A reconstruction of solar irradiance using a flux transport model  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

68

Solar spectral irradiance variability: what do we (not) know ?  

NASA Astrophysics Data System (ADS)

Solar spectral irradiance is an important driver for the Earth's atmosphere. The irradiance spectrum received by the Earth varies at all time scale and the amplitude of the (relative or absolute) depends strongly on the considered wavelengths. We will make a review of our current knowledge of solar irradiance variability based on observations, models and solar proxy, trying to identify points where no general agreement exists in the community. In more details, we will focus on the cycle and longer-term variations of the spectrum, based on the past and present observations and their agreement with models. We will also discuss the assumption behind the models and how proxy are used to estimate solar irradiance variations in the past. The research leading to these results has received funding from the European Community's Seventh Framework Program (FP7 2012) under grant agreement n° 313188 (SOLID)

Kretzschmar, Matthieu

2014-05-01

69

Atmosphere, Ocean, Land, and Solar Irradiance Data Sets  

NASA Technical Reports Server (NTRS)

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

Johnson, James; Ahmad, Suraiya

2003-01-01

70

Long-term reconstructions of total solar irradiance  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

71

White Paper on SBUV/2 Solar Irradiance Measurements  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

72

Searching for extraterrestrial civilizations.  

PubMed

We have argued that planning for a search for extraterrestrial intelligence should involve a minimum number of assumptions. In view of the feasibility (at our present level of understanding) of using nuclear fusion to effect interstellar travel at a speed of 0.1c, it appears unwarranted (at this time) to assume that it would not occur for at least some technologically advanced civilizations. One cannot even conclude that humans would not attempt this within the next few centuries. On the contrary, the most likely future situation, given the maintenance of technological growth and the absence of extraterrestrial interference, is that our civilization will explore and colonize our galactic neighborhood. A comparison of the time scales of galactic evolution and interstellar travel leads to the conclusion that the galaxy is either essentially empty with respect to technological civilizations or extensively colonized. In the former instance, a SETI would be unproductive. In the latter, a SETI could be fruitful if a signal has been deliberately directed at the earth or at an alien outpost, probe, or communication relay station in our solar system. In the former case, an existing antenna would probably be sufficient to detect the signal. In the latter case, success would depend on the way in which the communications were coded. Failure to detect a signal could permit any of the following conclusions: (i) the galaxy is devoid of technological civilizations, advanced beyond our own, (ii) such civilizations exist, but cannot (for some reason which is presently beyond our ken) engage in interstellar colonization, or (iii) such civilizations are not attempting overt contact with terrestrial civilizations and their intercommunications, if present, are not coded in a simple way. To plan at this time for a high-cost, large-array SETI based on the last two possibilities appears to be rather premature. PMID:17760037

Kuiper, T B; Morris, M

1977-05-01

73

Laboratory for Extraterrestrial Physics  

NASA Technical Reports Server (NTRS)

The NASA Goddard Space Flight Center (GSFC) Laboratory for Extraterrestrial Physics (LEP) performs experimental and theoretical research on the heliosphere, the interstellar medium, and the magnetospheres and upper atmospheres of the planets, including Earth. LEP space scientists investigate the structure and dynamics of the magnetospheres of the planets including Earth. Their research programs encompass the magnetic fields intrinsic to many planetary bodies as well as their charged-particle environments and plasma-wave emissions. The LEP also conducts research into the nature of planetary ionospheres and their coupling to both the upper atmospheres and their magnetospheres. Finally, the LEP carries out a broad-based research program in heliospheric physics covering the origins of the solar wind, its propagation outward through the solar system all the way to its termination where it encounters the local interstellar medium. Special emphasis is placed on the study of solar coronal mass ejections (CME's), shock waves, and the structure and properties of the fast and slow solar wind. LEP planetary scientists study the chemistry and physics of planetary stratospheres and tropospheres and of solar system bodies including meteorites, asteroids, comets, and planets. The LEP conducts a focused program in astronomy, particularly in the infrared and in short as well as very long radio wavelengths. We also perform an extensive program of laboratory research, including spectroscopy and physical chemistry related to astronomical objects. The Laboratory proposes, develops, fabricates, and integrates experiments on Earth-orbiting, planetary, and heliospheric spacecraft to measure the characteristics of planetary atmospheres and magnetic fields, and electromagnetic fields and plasmas in space. We design and develop spectrometric instrumentation for continuum and spectral line observations in the x-ray, gamma-ray, infrared, and radio regimes; these are flown on spacecraft to study the interplanetary medium, asteroids, comets, and planets. Suborbital sounding rockets and groundbased observing platforms form an integral part of these research activities. This report covers the period from approximately October 1999 through September 2000.

Vondrak, Richard R. (Technical Monitor)

2001-01-01

74

Reconstructions of solar irradiance on centennial time scales  

NASA Astrophysics Data System (ADS)

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

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

75

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

76

The solar spectral irradiances from x ray to radio wavelengths  

NASA Technical Reports Server (NTRS)

Sources of new measurements of the solar EUV, UV, and visible spectrum are presented together with discussion of formation of the solar spectrum as a problem in stellar atmospheres. Agreement between the data and a modern synthetic spectrum shows that observed radiative variability is a minor perturbation on a photosphere in radiative equilibrium and local thermodynamic equilibrium (LTE). Newly observed solar variability in 1992 defines a magnetic episode on the Sun closely associated with changes in both spectral irradiances and the total irradiance. This episode offers the opportunity to track the relationship between radiation and magnetic flux evolution.

White, O. R.

1993-01-01

77

A reconstruction of solar irradiance using a flux transport model  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

78

Estimating solar irradiance using a geostationary satellite  

E-print Network

regarding grid integrated solar power. In 2008, the State‘slarge amounts of solar power into the electric grid and thesolar resource and the effects of power fluctuations on the operation of the electric grid.

Urquhart, Bryan Glenn

2011-01-01

79

787980818283848586878889909192939495969798990001 SolarIrradiance(Wm-2  

E-print Network

.1% The SOHO Solar Cycle Mission #12;Captions for figures on the cover: Figure 8, top. The solar corona at 1 instruments over the last two solar cycles. The data in green are from SOHO VIRGO sensors Figure 12, bottom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 II. Goals: SOHO and NASA

Christian, Eric

80

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

81

VIRGO: Experiment for helioseismology and solar irradiance monitoring  

NASA Technical Reports Server (NTRS)

The scientific objectives of the variability of solar irradiance and gravity oscillations (VIRGO) experiment are as follows: to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations; to measure the solar total and spectral irradiance, and to quantify their variability. Helioseismological methods can be applied to these data in order to probe the solar interior. Certain convection characteristics and their interaction with magnetic fields will be studied from the results of the irradiance monitoring and from the comparison of the amplitudes and phases of the oscillations as observed from the brightness by VIRGO and from velocity by the global oscillations at low frequency (GOLF) experiment. The VIRGO experiment contains two active-cavity radiometers that monitor the solar constant, two three-channel sunphotometers that measure the spectral irradiance, and a low resolution imager with 12 pixels that measures the radiance distribution over the solar disk at 500 nm. The scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described, and their measured performances are given.

Froehlich, Claus; Andersen, Bo N.

1995-01-01

82

Spectrum line intensity as a surrogate for solar irradiance variations.  

PubMed

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

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

1988-06-24

83

Statistical Distribution of Solar Radiation: A European Data Set of Cumulative Frequency Curves of Solar Irradiance on Tilted Planes  

Microsoft Academic Search

The monthly frequency distribution of solar irradiance has now become a common meteorological input for solar energy system sizing methods, either directly or through the concept of “Utilizability”. Cumulative Frequency Curves (CFC) of solar irradiance were investigated within the frame of the European Solar Energy R and D Programme (Project F). The aim of this study was to prepare a

B. Bourges

1985-01-01

84

Investigation of Solar about 5-Month Cycle in Human Circulating Melatonin: Signature of Weather in Extraterrestrial Space?  

NASA Astrophysics Data System (ADS)

Melatonin, produced mainly in the pineal and the gut, is often thought of as the "dark hormone" as its concentration in the circulation is high during darkness and low during light in diurnally- and nocturnally-active mammals in health. About-daily and about-yearly periodicities can thus be anticipated to characterize melatonin, matching the two major photic environmental cycles. Non-photic solar influences have also been observed, melatonin being depressed in association with magnetic storms. While less stable than the daily and yearly changes, non-photic solar dynamics also undergo various periodicities. Among them is an about 0.42-year (about 5-month or 154-day) cycle, reported by several physicists in relation to Zürich relative sunspot numbers and to solar flares. This putative signature of solar activity was found in the incidence pattern of sudden cardiac death in Minnesota, USA, among other geographic locations. A cycle with a period of about 0.42 year is here reported in data on circulating melatonin of 172 patients studied between Oct 1992 and Dec 1995 in Florence, Italy. Melatonin may mediate some of the Sun's effects upon the biosphere in certain frequency-windows such as a cis-half-year of about 5 months.

Cornélissen, G.; Tarquini, R.; Perfetto, F.; Otsuka, K.; Gigolashvili, M.; Halberg, F.

2009-12-01

85

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

86

Analyzing UV-B narrowband solar irradiance: comparison with erythemal and vitamin D production irradiances.  

PubMed

The heliotherapy and the phototherapy are mainly focused on taking benefit of the therapeutic effects of the ultraviolet (UV) irradiance on different skin diseases. The use of UV-B narrowband lamps, with emissions centered at 311 nm, has spread out among the dermatologist community because of its high therapeutic effect in comparison with its low erythema dose. For cloudless sun exposure, the balance of solar erythemal and solar narrowband (NB)-equivalent irradiances depends on several factors such as the solar zenith angle (SZA), the total ozone column (TOC) and the altitude. For SZA below 55°, the ratio of solar UV-B narrowband and erythemal irradiances increases with the SZA whereas the ratio of vitamin D production and erythemal irradiances decreases with the SZA with the maximum around midday. Furthermore, the solar NB ratio also increases with the TOC because the shorter wavelengths of the erythemal action spectrum are more affected by the ozone absorption processes. Considering the daily variations of the ratio between narrowband and erythemal irradiance, sun exposures avoiding midday hours are recommended in order to prevent negative side-effects. However to accumulate great NB doses and sufficient vitamin D in winter months is difficult because the time exposures may be longer than the day duration. PMID:23092623

Sola, Yolanda; Lorente, Jerónimo; Ossó, Albert

2012-12-01

87

Solar spectral irradiance datasets: analysis and comparison with proxies  

NASA Astrophysics Data System (ADS)

Solar spectral irradiance (SSI) measurements have been acquired in space since the late 1960's. These data are of extreme importance to assess the variability of the Sun in the last decades as well as to understand how its magnetic activity affects its radiative output, and therefore to constrain the solar variability further in time. However, these data sometimes disagree between themselves or with our expectations deduced from well known observed proxies, and it is hard to disentangle instrumental effects from possible solar behavior. In the context of the european project SOLID (First European comprehensive SOlar Irradiance Data Exploitation) project, which aims at building an SSI composite with time dependent error-bars over the space age, we will show our first results towards the construction of a carefully assessed homogeneous solar spectral irradiance datasets, focussing on the ultraviolet wavelength range, for which more data are available. We will first present the data used, together with methods for gap-filling and outlier removal. Then we will show some results obtained by comparing a single dataset at different times of the mission, as well as results obtained from the comparison of simultaneous datasets and proxies. Finally, we will discuss how these analyses can help us to estimate errors on the solar variability at a particular wavelength.

Kretzschmar, M.; Schoell, M.; Dudok de Wit, T.

2013-12-01

88

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

89

Evolution of the solar irradiance during the Holocene  

NASA Astrophysics Data System (ADS)

Context. Long-term records of solar radiative output are vital for understanding solar variability and past climate change. Measurements of solar irradiance are available for only the last three decades, which calls for reconstructions of this quantity over longer time scales using suitable models. Aims: We present a physically consistent reconstruction of the total solar irradiance for the Holocene. Methods: We extend the SATIRE (Spectral And Total Irradiance REconstruction) models to estimate the evolution of the total (and partly spectral) solar irradiance over the Holocene. The basic assumption is that the variations of the solar irradiance are due to the evolution of the dark and bright magnetic features on the solar surface. The evolution of the decadally averaged magnetic flux is computed from decadal values of cosmogenic isotope concentrations recorded in natural archives employing a series of physics-based models connecting the processes from the modulation of the cosmic ray flux in the heliosphere to their record in natural archives. We then compute the total solar irradiance (TSI) as a linear combination of the jth and jth + 1 decadal values of the open magnetic flux. In order to evaluate the uncertainties due to the evolution of the Earth's magnetic dipole moment, we employ four reconstructions of the open flux which are based on conceptually different paleomagnetic models. Results: Reconstructions of the TSI over the Holocene, each valid for a different paleomagnetic time series, are presented. Our analysis suggests that major sources of uncertainty in the TSI in this model are the heritage of the uncertainty of the TSI since 1610 reconstructed from sunspot data and the uncertainty of the evolution of the Earth's magnetic dipole moment. The analysis of the distribution functions of the reconstructed irradiance for the last 3000 years, which is the period that the reconstructions overlap, indicates that the estimates based on the virtual axial dipole moment are significantly lower at earlier times than the reconstructions based on the virtual dipole moment. We also present a combined reconstruction, which represents our best estimate of total solar irradiance for any given time during the Holocene. Conclusions: We present the first physics-based reconstruction of the total solar irradiance over the Holocene, which will be of interest for studies of climate change over the last 11 500 years. The reconstruction indicates that the decadally averaged total solar irradiance ranges over approximately 1.5 W/m2 from grand maxima to grand minima. Appendix A is available in electronic form at http://www.aanda.orgThe TSI data is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A6

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

2011-07-01

90

The spectral nature of solar irradiance variability and its phase relationship to solar activity  

NASA Technical Reports Server (NTRS)

Rather firm conclusions regarding the nature of short term solar variability have been reached on the basis of recent studies of continuous time series of solar irradiance measurements. The measurements have been conducted with the aid of satellite mounted cavity radiometers. The present paper provides an interim report on further analysis concerning the spectral nature of solar variation and its relationship to other indicators of solar variability. It is pointed out that the Nimbus 7-ERB mission was able to deliver rather precise and continuous measures of solar irradiance at a variety of spectral bands. Spectral variations observed in the Nimbus 7-ERB solar monitor measurements appear to correspond to a quasi-black body shift due to the appearance of large earth-facing sun spots.

Smith, E. A.; Vonder Haar, T. H.; Hickey, J. R.; Maschhoff, R.

1983-01-01

91

The Search for Extraterrestrials  

NASA Astrophysics Data System (ADS)

It has been said that the discovery of an extraterrestrial intelligence will be the most important event in mankind’s history. For millennia, humans have been looking at the stars at night and wondering whether we are alone in the universe. Only with the advent of large-dish radio-frequency antennas and ultra-sensitive receivers in the late-twentieth century did it become possible to attempt a search for extraterrestrial intelligence (SETI).

Ross, Monte

92

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

93

Solar Forecasting System and Irradiance Variability Characterization  

E-print Network

.1 Photovoltaic Systems: Report 3 Development of data base allowing managed access to statewide PV and insolation. It also presents details of HNEI-developed statistical techniques for characterizing irradiance September 2014 HAWAI`I NATURAL ENERGY INSTITUTE School of Ocean & Earth Science & Technology ­ University

94

Solar Irradiance of the Earth's Atmosphere Sultana N. Nahar  

E-print Network

Solar Irradiance of the Earth's Atmosphere Sultana N. Nahar Department of Astronomy, The Ohio State of terrestrial atmospheric phenomena and energy source for the earth. It emits radiation over a large energy band and radiation fluxes. Variations in these emissions interact with all atmospheric layers down to the earth

Nahar, Sultana Nurun

95

Physiological Responses of Acropora cervicornis to Increased Solar Irradiance  

E-print Network

Physiological Responses of Acropora cervicornis to Increased Solar Irradiance Juan L. Torres*1 and photoprotective mycosporine-like amino acids (MAAs) were studied in the threatened Caribbean coral Acropora cervicornis transplanted from 20 to 1 m depth in La Parguera, Puerto Rico. The UVR exposure

Gilbes, Fernando

96

Solar Irradiance of the Earth's Atmosphere Sultana N. Nahar  

E-print Network

' surface to heat it up in an energy cycle. This phenomenon is known as the Greenhouse effect and has is being perturbed due to changes in atmospheric compositions of greenhouse gases. More energy is beingSolar Irradiance of the Earth's Atmosphere Sultana N. Nahar Department of Astronomy, The Ohio State

Nahar, Sultana Nurun

97

1978-1988 Total Solar Irradiance (TSI) Variability Trends  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

98

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

99

Recent solar extreme ultraviolet irradiance observations and modeling: A review  

NASA Technical Reports Server (NTRS)

For more than 90 years, solar extreme ultraviolet (EUV) irradiance modeling has progressed from empirical blackbody radiation formulations, through fudge factors, to typically measured irradiances and reference spectra was well as time-dependent empirical models representing continua and line emissions. A summary of recent EUV measurements by five rockets and three satellites during the 1980s is presented along with the major modeling efforts. The most significant reference spectra are reviewed and threee independently derived empirical models are described. These include Hinteregger's 1981 SERF1, Nusinov's 1984 two-component, and Tobiska's 1990/1991/SERF2/EUV91 flux models. They each provide daily full-disk broad spectrum flux values from 2 to 105 nm at 1 AU. All the models depend to one degree or another on the long time series of the Atmosphere Explorer E (AE-E) EUV database. Each model uses ground- and/or space-based proxies to create emissions from solar atmospheric regions. Future challenges in EUV modeling are summarized including the basic requirements of models, the task of incorporating new observations and theory into the models, the task of comparing models with solar-terrestrial data sets, and long-term goals and modeling objectives. By the late 1990s, empirical models will potentially be improved through the use of proposed solar EUV irradiance measurements and images at selected wavelengths that will greatly enhance modeling and predictive capabilities.

Tobiska, W. Kent

1993-01-01

100

Irradiance optimization of outdoor microalgal cultures using solar tracked photobioreactors.  

PubMed

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

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

2013-03-01

101

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

102

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

103

Solar Energy Monitor In Space (SEMIS)  

NASA Technical Reports Server (NTRS)

Measurements made at high altitudes from aircraft have resulted in the establishment of standard values of the solar constant and extraterrestrial solar spectral irradiance. These standard values and other solar spectral curves are described. The problem of possible variations of the solar constant and solar spectrum and their influence on the earth-atmosphere system and weather related phenomena is examined. It is shown that the solar energy input parameters should be determined with considerably greater accuracy and precision than has been possible. An instrument package designed as a compact, low weight solar energy monitor in space (SEMIS) is described.

Thekaekara, M. P.

1974-01-01

104

Tracking the Propagation of Solar Ultraviolet Radiation: Dispersal of Ultraviolet Photons in Inland Waters  

Microsoft Academic Search

Solar extraterrestrial ultraviolet radiation is tracked from its impingement upon the Earth's atmosphere to its dispersal in natural inland waters. This is accomplished through the use of a solar spectral irradiance model, a water column optical model, directly measured (AES monitoring network) values of ground-level ultraviolet radiation and stratospheric ozone, optical properties of aquatic matter indigenous to Lake Ontario and

John H. Jerome; Robert P. Bukata

1998-01-01

105

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

106

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

SciTech Connect

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

Reda, I.

2011-07-01

107

Some Impacts of Solar Irradiance Variation on Terrestrial Climate  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

108

Searching for extraterrestrial civilizations  

NASA Technical Reports Server (NTRS)

Three interrelated assumptions are critically examined in an attempt to outline a productive strategy for a search for extraterrestrial intelligence. Questions concerning the feasibility of interstellar travel are investigated. It is concluded that the probability of interstellar travel is high enough that, given a modest number of advanced civilizations, at least one of them will engage in interstellar voyages and colonize the galaxy. Assuming, however, that technological civilizations are rare the galaxy would be essentially unpopulated. Attention is given to the present lack of contact with extraterrestrial beings and frequencies for interstellar beacons.

Kuiper, T. B. H.; Morris, M.

1977-01-01

109

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

110

Fuzzy Sets Theory Applied for Computing Global Solar Irradiation  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

111

The sun’s total and spectral irradiance for solar energy applications and solar radiation models  

Microsoft Academic Search

Using the most recent composite time series of total solar irradiance spaceborne measurements, a solar constant value of 1366.1 Wm?2 is confirmed, and simple quadratic expressions are proposed to predict its daily value from the Zurich sunspot number, the MgII index, or the 10.7 cm radio flux index. Whenever these three indices are available on a daily basis (since 1978),

Christian A. Gueymard

2004-01-01

112

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

114

Searching for extraterrestrial civilizations  

Microsoft Academic Search

Three interrelated assumptions are critically examined in an attempt to outline a productive strategy for a search for extraterrestrial intelligence. Questions concerning the feasibility of interstellar travel are investigated. It is concluded that the probability of interstellar travel is high enough that, given a modest number of advanced civilizations, at least one of them will engage in interstellar voyages and

T. B. H. Kuiper; M. Morris

1977-01-01

115

Search for extraterrestrial intelligence  

Microsoft Academic Search

The findings of a series of workshops on the search for extraterrestrial intelligence are presented. The major conclusions of the deliberations are presented. Six of the most interesting and significant elements of the debate are presented in the form of Colloquies. A selection of detailed technical arguments about various aspects of the SETI endeavor is documented. (GHT)

P. Morrison; J. Billingham; J. Wolfe

1979-01-01

116

ExtraTerrestrial Intelligence  

E-print Network

SETI Search for ExtraTerrestrial Intelligence I know perfectly well that at this moment the whole, The Madwoman of Chaillot #12;Options Passive SETI: Listen Active SETI: Transmit #12;Search Strategies Suppose you find a civilization. You want to communicate. How? #12;Search Strategies There are two issues: A

Walter, Frederick M.

117

Solar EUV Spectral Irradiance Throughout The 3-Dimensional Heliosphere  

NASA Astrophysics Data System (ADS)

When Ulysses moved from 30 to 80 degrees in solar latitude (July 2001), the Ulysses GAS instrument measured an apparent increase in the neutral He density. This is more naturally interpreted as a latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than a true increase of the neutral He density. This concept has been tested through the development of a 3-Dimensional solar EUV model for the Heliosphere. The model concept has been presented earlier, and we are now presenting results and applications of the new model. Using daily SOHO EIT observations, over successive Carrington rotations, we have developed a three- dimensional model for solar EUV fluxes observed at any heliospheric position, projected to any heliospheric position. The combined effects of solar rotational and latitude-dependent flux variability are explicitly treated in this model. The flux model will be compared with other direct spectral irradiance observations in the ecliptic plane, such as those available from the TIMED SEE instrument as well as broadband measurements available from the SOHO/SEM irradiance time series. These comparisons will be used in part to validate the current results. We then use this flux to compute the photoionization rate of the in-flowing neutral Helium, and compare the modeled change with that observed along the spacecraft trajectory with the direct measurements from the out-of-ecliptic Ulysses GAS observations. The unique GAS comparisons will provide validation of the original hypothesis as to the latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than an increase of the neutral He density.

McMullin, D. R.; Auchere, F.; Cook, J. W.; Newmark, J. S.; Quemerais, E.; von Steiger, R.; Witte, M.

2008-12-01

118

A Critical Review of the Time Series of Total Solar Irradiance Satellite Observations  

Microsoft Academic Search

Continuous time series of total solar irradiance (TSI) observations have been constructed from the set of contiguous, redundant, overlapping total solar irradiance (TSI) measurements made by satellite experiments during the past 28 years. One, the ACRIM composite time series [Willson &Mordvinov, 2003], detects a significant upward trend in TSI of 0.04 percent per decade during solar cycles 21-23. Another, the

R. C. Willson

2006-01-01

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

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

121

Surface solar irradiance from SCIAMACHY measurements: algorithm and validation  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

122

Surface solar irradiance from SCIAMACHY measurements: algorithm and validation  

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

123

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

124

Modelling solar irradiance from HRV images of Meteosat Second Generation  

NASA Astrophysics Data System (ADS)

Knowledge of solar radiation at the earth's surface is a need in designing any solar energy application. In particular both photovoltaic and solar thermal systems required high accurate data of solar radiation components. Nowadays the use of satellite images as input to models for deriving solar irradiance time series is accepted as a reliable methodology with good accuracy. In this sense, there are several models aimed at this objective. Among them it can be pointed out the Heliosat-2 method, based upon the first generation of Meteosat satellites, which has been broadly used. Taken this approach as reference a modified model was proposed including additional independent variables to the cloud index, such as the moments of the cloud index distribution and the air mass. This model was successfully assessed with about 30 ground data sites in Spain showing a good response. However, since 2006 the Meteosat Second Generation (MSG) is observing the earth-atmosphere system centred in zero longitude. This new satellite generation has improved technical characteristics compared to the former one, particularly those focused on radiometric, spectral, spatial and time resolutions. This work is aimed at describing the work to accommodate the former model based on Heliosat-2 to operate with the MSG images and characteristics. A comparison with the old model will be made in the overlapping period, 2006, and an assessment with available ground data will also be performed as well.

Cony, Marco; Zarzalejo, Luis; Polo, Jesús; Marchante, Ruth; Martín, Luis

2010-05-01

125

Time-delayed upper atmospheric responses to solar EUV irradiation  

NASA Astrophysics Data System (ADS)

It is well recognized that solar EUV irradiations at various wavelengths are the dominant driver of the quiet-time upper atmospheric variations, including thermospheric temperature and densities, as well as ionospheric density and temperatures. However, responses of the upper atmosphere have been found not as straightforward as expected, but rather complicated with time-delays for approximately 2 days relative to solar flux proxy F10.7. Using measurements of TIMED/SEE solar UV flux at various wavelengths and incoherent scatter radar-based ionospheric and thermospheric parameters, this paper addresses characteristic upper atmospheric variability on the time scales from hours to days, and the associated solar UV variations. It is found that exospheric temperature Tex is most sensitive to solar EUV flux with an approximately 2-day delay at wavelengths of 27--34 nm (including 30.4 nm). In fact, a 20--60-hour time delay occurs in Tex response to EUV flux at the 27-34 nm band, with shorter delays in the morning and longer delays in the afternoon and at night. Ionospheric electron delays are altitude dependent: in the E-region, there is no time delay, and in the F2 region, there exist delays for 2-3 days in both electron density and ion temperature. These delays are perhaps representatives of the upper atmospheric memory and will be discussed in the paper.

Zhang, Shunrong; Erickson, Philip; Goncharenko, Larisa

2015-04-01

126

Reconstruction of total solar irradiance 1974-2009  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

127

Inferences of all-sky solar irradiance using Terra and Aqua MODIS satellite data  

Microsoft Academic Search

Solar irradiance is a key environmental control, and accurate spatial and temporal solar irradiance data are important for a wide range of applications related to energy and carbon cycling, weather prediction, and climate change. This study presents a satellite-based scheme for the retrieval of all-sky solar irradiance components, which links a physically based clear-sky model with a neural network version

R. Houborg; H. Soegaard; W. Emmerich; S. Moran

2007-01-01

128

Extraterrestrial Handedness: A Reply  

NASA Astrophysics Data System (ADS)

Recent investigations of stable isotope ratios of amino acids from the Murchison meteorite have shown them to be of unambiguous extraterrestrial origin, and examinations of their enantiomeric compositions, where terrestrial contamination can be excluded, have found a consistent excess of L-enantiomers. One explanation for this observation has been the asymmetric photolysis of racemic extraterrestrial amino acids by circularly polarized light (CPL) in the synchrotron radiation from orbiting electrons around the pulsar remnants of supernovae. Mason (1997) has attempted to discredit this mechanism on the grounds that circular dichroism (CD) bands for optically active molecules alternate in sign and sum to zero over the entire spectrum, and hence enantioselective photochemical reactions cannot be induced by broad band CPL. We submit arguments disputing this conclusion and present reasons for expecting that broad band CPL synchrotron radiation would be quite capable of inducing asymmetric photolysis, particularly in aliphatic amino acids.

Bonner, William A.; Rubenstein, Edward; Brown, George S.

1999-05-01

129

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

NASA Technical Reports Server (NTRS)

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

Woods, Thomas N.; Rottman, Gary J.

1990-01-01

130

Microorganisms and extraterrestrial travel  

Microsoft Academic Search

I am taking as given that more practical means of space travel than exist now will be developed in the next century or two\\u000a and that colonization — actual settlement — of extraterrestrial bodies will follow. Neither of these is certain or even close\\u000a to certain, but they might happen, and if they do, problems will arise about which we

Alfred W. Crosby

131

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

132

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

133

First Solar EUV Irradiances Obtained from SOHO by the Celias\\/Sem  

Microsoft Academic Search

The first results obtained with the Solar EUV Monitor (SEM), part of the Charge, Element, and Isotope Analysis System (CELIAS) instrument, aboard the SOlar and Heliospheric Observatory (SOHO) satellite are presented. The instrument monitors the full-disk absolute value of the solar Heii irradiance at 30.4 nm, and the full-disk absolute solar irradiance integrated between 0.1 nm and 77 nm. The

D. L. Judge; D. R. McMullin; H. S. Ogawa; D. Hovestadt; B. Klecker; M. Hilchenbach; E. Möbius; L. R. Canfield; R. E. Vest; R. Watts; C. Tarrio; M. Kühne; P. Wurz

1998-01-01

134

[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

135

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

PubMed Central

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

Zurbenko, Igor

2014-01-01

136

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

137

Analysis of clear hour solar irradiation for seven Canadian stations  

SciTech Connect

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

Garrison, J.; Sahami, K. [San Diego State Univ., CA (United States)] [San Diego State Univ., CA (United States)

1995-12-31

138

THE EFFECT OF THE TRANSIT OF VENUS ON ACRIM'S TOTAL SOLAR IRRADIANCE MEASUREMENTS: IMPLICATIONS FOR TRANSIT  

E-print Network

THE EFFECT OF THE TRANSIT OF VENUS ON ACRIM'S TOTAL SOLAR IRRADIANCE MEASUREMENTS: IMPLICATIONS North Cherry Avenue, Tucson, AZ 85721; gschneider@as.arizona.edu J. M. Pasachoff Williams College of the ToV on the total solar irradiance (TSI). Contemporaneous high-resolution broadband imagery with NASA

Schneider, Glenn

139

Spatial and spectral non-uniform irradiance distribution effects on multijunction solar cells  

Microsoft Academic Search

When refractive optical systems are used to concentrate light onto high efficiency solar cells chromatic aberration creates irradiance distributions over the cells which are neither spatially nor spectrally uniform. Multijunction solar cells are the photovoltaic device with the highest conversion efficiency. However, their efficiency under a concentration system can be significantly lower than the measured efficiency under uniform irradiance and

M. Victoria; R. Herrero; C. Domínguez; I. Antón; S. Askins; G. Sala

2011-01-01

140

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

141

INFERENCES OF ALL-SKY SOLAR IRRADIANCE USING TERRA AND AGUA MODIS SATELLITE DATA 1763  

Technology Transfer Automated Retrieval System (TEKTRAN)

Solar irradiance is a key environmental control and accurate spatial and temporal solar irradiance data are important for a wide range of applications related to energy and carbon cycling, weather prediction and climate change. This study presents a satellite-based scheme for the retrieval of all-sk...

142

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.

2014-08-01

143

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

144

Identification of Extraterrestrial Microbiology  

NASA Technical Reports Server (NTRS)

Many of the key questions addressed in the field of Astrobiology are based upon the assumption that life exists, or at one time existed, in locations throughout the universe. However, this assumption is just that, an assumption. No definitive proof exists. On Earth, life has been found to exist in many diverse environment. We believe that this tendency towards diversity supports the assumption that life could exists throughout the universe. This paper provides a summary of several innovative techniques for the detection of extraterrestrial life forms. The primary questions addressed are does life currently exist beyond Earth and if it does, is that life evolutionary related to life on Earth?

Flynn, Michael; Rasky, Daniel J. (Technical Monitor)

1998-01-01

145

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

146

Possible extraterrestrial strategy for earth  

Microsoft Academic Search

A hypothesis concerning the nature of extraterrestrial messages to the earth is proposed. The hypothesis is based on the following assumptions about (1) that they exist in abundance in the Galaxy; (2) that they are benevolent toward earth-based life forms, and (3) that the lack of any human detection of extraterrestrials is due to an embargo designed to prevent any

J. W. Deardorff

1986-01-01

147

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

148

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

149

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

150

Correlation of solar irradiance and atmospheric temperature variations derived from spacecraft radiometry  

NASA Technical Reports Server (NTRS)

Long-term changes in the mean global atmospheric temperature and the total solar irradiance were examined utilizing 1979-1989 spacecraft measurements. Outgoing longwave radiation at the top of the atmosphere was employed to infer global atmospheric temperatures. Evidence was determined that indicates the global temperatures should decline in the 1990-1997 period as the magnitude of the incoming solar irradiance declines with decreasing solar magnetic activity.

Lee, Robert B., III; Bolden, William C.; Gibson, M. A.; Paden, Jack; Pandey, Dhirendra K.; Thomas, Susan; Wilson, Robert S.

1992-01-01

151

Modelling total solar irradiance since 1878 from simulated magnetograms  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

152

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

153

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

154

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

155

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

156

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

157

Empirical validation of models to compute solar irradiance on inclined surfaces for building energy simulation  

Microsoft Academic Search

Accurately computing solar irradiance on external facades is a prerequisite for reliably predicting thermal behavior and cooling loads of buildings. Validation of radiation models and algorithms implemented in building energy simulation codes is an essential endeavor for evaluating solar gain models. Seven solar radiation models implemented in four building energy simulation codes were investigated: (1) isotropic sky, (2) Klucher, (3)

P. G. Loutzenhiser; H. Manz; C. Felsmann; P. A. Strachan; T. Frank; G. M. Maxwell

2007-01-01

158

Extraterrestrial Organic Compounds in Meteorites  

NASA Technical Reports Server (NTRS)

Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

2003-01-01

159

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

160

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

161

The Case for the Extraterrestrial Origin of Flying Saucers  

Microsoft Academic Search

Careful review of a vast array of relevant evidence clearly leads to the conclusion that some unidentified flying objects are intelligently controlled vehicles whose origin is outside our solar system. All the arguments against the extraterrestrial origin seem to be based upon false reasoning, misrepresentation of evidence, neglect of relevant information, ignorance of relevant technology, or pseudo sophisticated assumptions about

Stanton T. Friedman; Pembroke Crescent

162

Optical Search for Extraterrestrial Intelligence with Air Cerenkov Telescopes  

Microsoft Academic Search

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

David Eichler; Gregory Beskin

2001-01-01

163

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.

164

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

165

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

166

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

167

Extraterrestrial Radiation Chemistry and Molecular Astronomy  

NASA Technical Reports Server (NTRS)

Astronomical observations of both solar system and interstellar regions have revealed a rich chemical inventory that includes most classes of organic molecules and selected inorganics. For example, gas-phase ethylene glycol and SOz have been observed by astronomers, while solidphase detections include OCS, H2O2 , and the cyanate anion.' All of these are found in environments that are, by earthly standards, exceedingly hostile: temperatures of 10 - 100 K, miniscule densities, and near-ubiquitous ionizing-radiation fields. Beyond the simplest chemical species, these conditions have made it difficult-to-impassible to account for the observed molecular abundances using gas-phase chemistry, suggesting solid-phase reactions play an important role. In extraterrestrial environments, cosmic rays, UV photons, and magnetospheric radiation all drive chemical reactions, even at cryogenic temperatures. To study this chemistry, radiation astrochemists conduct experiments on icy materials, frozen under vacuum and exposed to sources such as keV electrons and MeV protons. Compositional changes usually are followed with IR spectroscopy and, in selected cases, more-sensitive mass-spectral techniques. This talk will review some recent results on known and suspected extraterrestrial molecules and ions. Spectra and reaction pathways will be presented, and predictions made for interstellar chemistry and the chemistry of selected solar system objects. Some past radiation-chemical contributions, and future needs, will be explored.

Hudson, Reggie L.; Moore, Marla H.

2009-01-01

168

A Technique for Global Monitoring of Net Solar Irradiance at the Ocean Surface. Part II: Validation  

Microsoft Academic Search

The present study constitutes the generation and validation of the first satellite-based, long-term record of surface solar irradiance over the global oceans. The record is generated using Nimbus-7 earth radiation budget (ERB) wide-field-of-view (WFOV) planetary-albedo data as input to a numerical algorithm designed and implemented for this study based on radiative transfer theory. Net surface solar irradiance is obtained by

Beth Chertock; Robert Frouin; Catherine Gautier

1992-01-01

169

In-Flight Performance of the Virgo Solar Irradiance Instruments on Soho  

Microsoft Academic Search

The in-flight performance of the total and spectral irradiance instruments within VIRGO (Variability of solar IRradiance and\\u000a Gravity Oscillations) on the ESA\\/NASA Mission SOHO (SOlar and Heliospheric Observatory) is in most aspects better than expected.\\u000a The behaviour during the first year of operation of the two types of radiometers and the sunphotometers together with a description\\u000a of their data evaluation

Claus Fröhlich; Dominique A. Crommelynck; Christoph Wehrli; Martin Anklin; Steven Dewitte; Alain Fichot; Wolfgang Finsterle; Antonio Jiménez; André Chevalier; Hansjörg Roth

1997-01-01

170

Photodegradation of veterinary ionophore antibiotics under UV and solar irradiation.  

PubMed

The veterinary ionophore antibiotics (IPAs) are extensively used as coccidiostats and growth promoters and are released to the environment via land application of animal waste. Due to their propensity to be transported with runoff, IPAs likely end up in surface waters where they are subject to photodegradation. This study is among the first to investigate the photodegradation of three commonly used IPAs, monensin (MON), salinomycin (SAL) and narasin (NAR), under UV and solar irradiation. Results showed that MON was persistent in a deionized (DI) water matrix when exposed to UV and sunlight, whereas SAL and NAR could undergo direct photolysis with a high quantum yield. Water components including nitrate and dissolved organic matter had a great impact on the photodegradation of IPAs. A pseudosteady state kinetic model was successfully applied to predict IPAs' photodegradation rates in real water matrices. Applying LC/MS/MS, multiple photolytic transformation products of IPAs were observed and their structures were proposed. The direct photolysis of SAL and NAR occurred via cleavage on the ketone moiety and self-sensitized photolysis. With the presence of nitrate, MON was primarily degraded by hydroxyl radicals, whereas SAL showed reactivity toward both hydroxyl and nitrogen-dioxide radicals. Additionally, toxicity tests showed that photodegradation of SAL eliminated its antibiotic properties against Bacillus subtilis. PMID:25343749

Sun, Peizhe; Pavlostathis, Spyros G; Huang, Ching-Hua

2014-11-18

171

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

172

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

NASA Technical Reports Server (NTRS)

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

Lee, Robert B., III

1992-01-01

173

Results of aperture area comparisons for exo-atmospheric total solar irradiance measurements.  

PubMed

Exo-atmospheric solar irradiance measurements made by the solar irradiance community since 1978 have incorporated limiting apertures with diameters measured by a number of metrology laboratories using a variety of techniques. Knowledge of the aperture area is a critical component in the conversion of radiant flux measurements to solar irradiance. A National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) sponsored international comparison of aperture area measurements of limiting apertures provided by solar irradiance researchers was performed, the effort being executed by the National Institute of Standards and Technology (NIST) in coordination with the EOS Project Science Office. Apertures that had institutional heritage with historical solar irradiance measurements were measured using the absolute aperture measurement facility at NIST. The measurement technique employed noncontact video microscopy using high-accuracy translation stages. We have quantified the differences between the participating institutions' aperture area measurements and find no evidence to support the hypothesis that preflight aperture area measurements were the root cause of discrepancies in long-term total solar irradiance satellite measurements. Another result is the assessment of uncertainties assigned to methods used by participants. We find that uncertainties assigned to a participant's values may be underestimated. PMID:24513747

Johnson, B Carol; Litorja, Maritoni; Fowler, Joel B; Shirley, Eric L; Barnes, Robert A; Butler, James J

2013-11-20

174

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

175

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

176

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

177

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

NASA Astrophysics Data System (ADS)

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

Wang, Hongrui; Fang, Wei; Li, Huiduan

2015-04-01

178

Finding extraterrestrial organisms living on thermosynthesis.  

PubMed

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. PMID:14678664

Muller, Anthonie W J

2003-01-01

179

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.

180

FIRST RESULTS FROM VIRGO, THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO  

Microsoft Academic Search

First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA\\/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the

Claus Frohlich; Bo N. Andersen; Thierry Appourchaux; Gabrielle Berthomieu; Dominique A. Crommelynck; Vicente Domingo; Alain Fichot; Wolfgang Finsterle; Maria F. Gómez; Douglas Gough; Antonio Jimenez; Torben Leifsen; Marc Lombaerts; Judit M. Pap; Janine Provost; Teodoro Roca Cortés; Jose Romero; Hansjorg Roth; Takashi Sekii; Udo Telljohann; Thierry Toutain; Christoph Wehrli

1997-01-01

181

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

182

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

183

First results of statistical analysis applied on different solar spectral irradiance datasets acquired from different satellites  

NASA Astrophysics Data System (ADS)

Spectral solar irradiance (SSI) datasets are crucial input to atmospheric and climate modelling. The spectral and total solar irradiances (SSI and TSI) change on scales ranging from few days up to the 11-yr sunspot cycle. The European comprehensive SOLar Irradiance Data exploitation (SOLID) project aims at providing a uniform dataset of observed SSI data from the beginning of the space era to the present for the time period of around thirty years from a combination of satellite datasets. As a first step continuous wave and FFT analyses are applied to different observational datasets to diagnose and characterize the variability of the datasets and compare the results to commonly used solar proxies like Mg II and photometric sunspot indices. First results are presented.

Chehade, Wissam; Weber, Mark; Burrows, John P.

2014-05-01

184

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.

185

Dynamic mesh-based analysis of irradiance characteristics of solar simulator  

NASA Astrophysics Data System (ADS)

The unsteady motion of a solar simulator was simulated using dynamic mesh technology in Fluent software. The dynamic irradiation characteristics of the simulator were studied under various conditions. Mesh updates were achieved using a dynamic layering method, and the periodic lifting motion of the simulator was defined using user-defined functions (UDF). Detailed dynamic irradiance characteristics were obtained for comparison with experimental results. The results showed that the simulator height and the number of light sources used were the main factors that affected the irradiance. The irradiance has a linear relationship with the simulator height, which means that the irradiance nonuniformity decreases with decreasing solar height; in addition, the sum of the irradiances under the various operating conditions matches the superposition of the irradiance. The dynamic irradiation numerical results are consistent with the experimental results at typical points, which verifies the reliability of the moving mesh numerical model. The validated model can be used to study various simulator conditions and provides forecast data for diurnal variation simulation of solar radiation.

Meng, Qinglong; Li, Yanpeng; Gu, Yaxiu

2014-09-01

186

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

187

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

USGS Publications Warehouse

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

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

2000-01-01

188

Detection of Extraterrestrial Ecology (Exoecology)  

NASA Technical Reports Server (NTRS)

Researchers in the Astrobiology Technology Branch at Ames Research Center have begun investigating alternate concepts for the detection of extraterrestrial life. We suggest searching for extraterrestrial ecology, exoecology, as well as for extraterrestrial biology, exobiology. Ecology describes the interactions of living things with their environment. All ecosystems are highly constrained by their environment and are constrained by well-known system design principles. Ecology could exist wherever there is an energy source and living I things have discovered some means to capture, store, and use the available energy. Terrestrial ecosystems use as energy sources, light, organic molecules, and in thermal vents and elsewhere, simple inorganic molecules. Ecosystem behavior is controlled by matter and energy conservation laws and can be described by linear and nonlinear dynamic systems theory. Typically in an ecosystem different molecules are not in chemical equilibrium and scarce material is conserved, stored, or recycled. Temporal cycles and spatial variations are often observed. These and other -eneral principles of exoecology can help guide the search for extraterrestrial life. The chemical structure observed in terrestrial biology may be highly contingent on evolutionary accidents. Oxygen was not always abundant on Earth. Primitive sulfur bacteria use hydrogen sulfide and sulfur to perform photosynthesis instead of water and oxygen. Astrobiologists have assumed, for the sake of narrowing and focusing our life detection strategies, that extraterrestrial life will have detailed chemical similarities with terrestrial life. Such assumptions appear very reasonable and they allow us to design specific and highly sensitive life detection experiments. But the fewer assumptions we make, the less chance we have of being entirely wrong The best strategy for the detection of extraterrestrial life could be a mixed strategy. We should use detailed assumptions based on terrestrial biology to guide some but not all future searches for alien life. The systems principles of exoecology seem much more fundamental and inescapable than the terrestrial biology analogies of exobiology. We should search for exoecology as well as exobiology.

Jones, Harry; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

189

ADVANCING THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE  

E-print Network

ADVANCING THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE Jill Tarter SETI Institute 515 N. Whisman ­ Space Sciences Lab, UC Berkeley #12;Advancing the Search for Extraterrestrial Intelligence Executive for extraterrestrial intelligence. Today SETI falls under the umbrella of astrobiology, a suite of cross

190

Segmentation of coronal features to understand the solar EUV and UV irradiance variability  

NASA Astrophysics Data System (ADS)

Context. The study of solar irradiance variability is of great importance in heliophysics, the Earth's climate, and space weather applications. These studies require careful identifying, tracking and monitoring of active regions (ARs), coronal holes (CHs), and the quiet Sun (QS). Aims: We studied the variability of solar irradiance for a period of two years (January 2011-December 2012) using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Methods: We used the spatial possibilistic clustering algorithm (SPoCA) to identify and segment coronal features from the EUV observations of AIA. The AIA segmentation maps were then applied on SWAP images, and parameters such as the intensity, fractional area, and contribution of ARs/CHs/QS features were computed and compared with the full-disk integrated intensity and LYRA irradiance measurements. Results: We report the results obtained from SDO/AIA and PROBA2/SWAP images taken from January 2011 to December 2012 and compare the resulting integrated full-disk intensity with PROBA2/LYRA irradiance. We determine the contributions of the segmented features to EUV and UV irradiance variations. The variations of the parameters resulting from the segmentation, namely the area, integrated intensity, and relative contribution to the solar irradiance, are compared with LYRA irradiance. We find that the active regions have a great impact on the irradiance fluctuations. In the EUV passbands considered in this study, the QS is the greatest contributor to the solar irradiance, with up to 63% of total intensity values. Active regions, on the other hand, contribute to about 10%, and off-limb structures to about 24%. We also find that the area of the features is highly variable suggesting that their area has to be taken into account in irradiance models, in addition to their intensity variations. Conclusions: We successfully show that the feature extraction allows us to use EUV telescopes to measure irradiance fluctuations and to quantify the contribution of each part to the EUV spectral solar irradiance observed with a calibrated radiometer. This study also shows that SPoCA is viable, and that the segmentation of images can be a useful tool. We also provide the measurement correlation between SWAP and AIA during this analysis.

Kumara, S. T.; Kariyappa, R.; Zender, J. J.; Giono, G.; Delouille, V.; Chitta, L. P.; Damé, L.; Hochedez, J.-F.; Verbeeck, C.; Mampaey, B.; Doddamani, V. H.

2014-01-01

191

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

192

Variations in Solar Activity and Irradiance and Their Implications for Energy Input Into the Terrestrial Atmosphere  

NASA Astrophysics Data System (ADS)

This dissertation presents research into the question of how variations in the physical properties of resolved solar magnetic surface features combine to produce variations in the physical properties of the integrated Sun and the possible impacts of those variations on the terrestrial climate system. The core approach to the research was development of techniques to apply automated Bayesian statistical pattern recognition methods as implemented in the AutoClass software to magnetic and intensity-like solar images from the Mount Wilson Solar Observatory (MWO) 150 Foot Solar Telescope. The goals were to: (1) identify in an objective and quantifiable manner the solar surface features responsible for changes in solar irradiance, (2) enhance understanding of the evolution of these features and the resultant solar irradiance variations over the most recent solar cycles, (3) develop methods to identify the specific features responsible for variations in specific wavelengths, (4) use global observations of global solar irradiance indices to identify the spatially resolved features which contribute to them, (5) attempt to apply these results to specific topics of current interest in solar-stellar astronomy. Using these techniques, a method was developed to identify classes of features from thousands of MWO solar images based on the per pixel values of absolute magnetic field strength and an intensity measure known as a "ratio-gram" in MWO images. Using these classes along with observations from independent, usually satellite based, sources in different wavelengths, models were constructed of total solar irradiance (TSI) and solar UV indices. These models were able to reproduce with high correlations solar observations in a number of different solar wavelengths. These classes were also used to construct images mapping different wavelength emissions to the areas to the solar surface features from which they originated. These techniques proved able to reproduce with high accuracy many of the different wavelengths comprising solar irradiance and to identify the features producing them on the solar surface. The results of this research imply constraints on the fraction of variations in solar TSI and other wavelength emissions which can be accounted for by magnetic field variations without resort to other explanatory mechanisms. These findings in turn imply constraints on the extent to which variations in solar irradiance may be a factor contributing to observed global warming. These findings include: (1) constraining possible non-magnetic sources of TSI variations to a range of 5--6% versus 10--20% in earlier research, suggesting a limitation on solar TSI forcing of terrestrial climate to the 0.1% solar cycle variations in magnetic activity and (2) a failure to find an upward minimum to minimum trend in TSI from Cycle 21/22 to 22/23 such as reported by others and the detection of a downward trend from the Cycle 22/23 to 23/24 minimum. The results are also useful diagnostics for the inference of the surface properties study of solar-type stars for which resolved spatial images are not available.

Parker, Daryl Gray

193

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

SciTech Connect

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 expensive, first-class, thermopile-based radiometers respond fairly uniformly to all solar wavelengths. While the total horizontal and direct normal solar irradiance measurements made with the MFRSR unfiltered silicon channel are reasonable if carefully calibrated with a thermopile radiometer, the diffuse horizontal irradiance calibrated in this way has a large bias. These issues are common to all inexpensive, silicon-cell, solar pyranometers. In this paper we use a multivariate, linear regression technique for approximating the thermopile-measured total, diffuse, and direct broadband solar irradiances using the six, narrowband filters and the open-channel of an MFRSR. The calibration of the MFRSR for broadband solar by comparing various combinations of MFRSR channels to first-class thermopile instruments is illustrated, and methods to track the instrument response during field deployments are investigated. We also suggest an approach to calibrate the open-channel for all three components that could improve measurements that are made using typical, commercial, silicon-cell pyranometers. (author)

Michalsky, J.J.; Augustine, J.A. [National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305 (United States); Kiedron, P.W. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, 325 Broadway, Boulder, CO 80305 (United States)

2009-12-15

194

SDI: Solar Dome Instrument for Solar Irradiance Monitoring Tao Liu1, Ankur U. Kamthe1, Varick L. Erickson1, Carlos F. M. Coimbra2 and Alberto E. Cerpa1  

E-print Network

SDI: Solar Dome Instrument for Solar Irradiance Monitoring Tao Liu1, Ankur U. Kamthe1, Varick L data for ground solar irradiance (direct normal and global irradiance) is a major obstacle for the de- velopment of adequate policies to promote and take advan- tage of existing solar technologies. Although

Cerpa, Alberto E.

195

State-of-the-art Instruments for Detecting Extraterrestrial Life  

NASA Technical Reports Server (NTRS)

In the coming decades, state-of-the-art spacecraft-based instruments that can detect key components associated with life as we know it on Earth will directly search for extinct or extant extraterrestrial life in our solar system. Advances in our analytical and detection capabilities, especially those based on microscale technologies, will be important in enhancing the abilities of these instruments. Remote sensing investigations of the atmospheres of extrasolar planets could provide evidence of photosynthetic-based life outside our solar system, although less advanced life will remain undetectable by these methods. Finding evidence of extraterrestrial life would have profound consequences both with respect to our understanding of chemical and biological evolution, and whether the biochemistry on Earth is unique in the universe.

Bada, Jeffrey L.

2003-01-01

196

The search for extraterrestrial intelligence  

Microsoft Academic Search

The modern era of the search for extraterrestrial technological intelligence (SETI) began in 1960 when a radiotelescope was used to see if any messages were being sent from the vicinity of two nearby stars. Since then there have been many searches, and not just with radiotelescopes. So far ETI has not been found, but the search has only just begun.

Barrie W Jones

2003-01-01

197

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

198

The role of extraterrestrial phenomena in extinction  

NASA Technical Reports Server (NTRS)

In the several years since the Alvarez report of anomalously high iridium concentrations at the Cretaceous-Tertiary boundary, evidence for the involvement of meteorite impacts in biological extinction has increased dramatically. Much more research will be needed, however, before meteorite impact is established as a general causal factor in extinction. Of ever greater long-term interest is the possibility that other extraterrestrial forces have had important influences on the evolution of life. To recognize the effects of such forces, it will be necessary to coordinate the research of astronomy and paleontology so that testable predictions can be formulated. It is possible that known, systematic changes in the Solar System or Galaxy have had effects on global biology and that these effects have been preserved in the paleontological record.

Raup, D. M.

1988-01-01

199

Nuclear power: key to man's extraterrestrial civilization  

SciTech Connect

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 energy sources for power and propulsion, (2) the creation of permanent manned habitats in space, and (3) the ability to process materials anywhere in the Solar System. In the 1990s and beyond, nuclear reactors could represent the prime source of both space power and propulsion. The manned and unmanned space missions of tomorrow will demand first kilowatt and then megawatt levels of power. Various nuclear power plant technologies will be discussed, with emphasis on derivatives from the nuclear rocket technology.

Angelo, J.A. Jr.; Buden, D.

1982-01-01

200

Can Collimated Extraterrestrial Signals be Intercepted?  

E-print Network

The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrowband pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between two star systems with a vector that unintentionally intersects the Solar System, allowing Earth to intercept the communication. But should we expect to be able to intercept these unintentional signals? And what constraints can we place upon the frequency of intelligent civilisations if we do? We carry out Monte Carlo Realisation simulations of interstellar communications between civilisations in the Galactic Habitable Zone (GHZ) using collimated beams. We measure the frequency with which beams between two stars are intercepted by a third. The interception rate increases linearly with the fraction of communicating civilisations, and as the cube of the beam opening angle, which is somewhat stronger than theoretical expectations, which we argue is due to the geometry of the GHZ...

Forgan, Duncan H

2014-01-01

201

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

202

A lunar base for SETI (Search for Extraterrestrial Intelligence)  

NASA Technical Reports Server (NTRS)

The possibilities of using lanar based radio antennas in search of intelligent extraterrestrial communications is explored. The proposed NASA search will have two search modes: (1) An all sky survey covering the frequency range from 1 to 10 GHz; and (2) A high sensitivity targeted search listening for signals from the approx. 800 solar type stars within 80 light years of the Sun, and covering 1 to 3 GHz.

Oliver, Bernard M.

1988-01-01

203

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

204

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

205

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

206

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

PubMed

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. PMID:20370214

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

2010-03-01

207

Extraterrestrial Mössbauer spectrometry.  

NASA Astrophysics Data System (ADS)

The authors describe a combined backscatter Mössbauer spectrometer and X-ray fluorescence analyzer (BaMS/XRF) instrument suitable for planetary missions to the surfaces of Mars (MESUR Program), the Moon, asteroids, or other solid-solar-system objects. The BaMS/XRF instrument is designed to be capable of concurrent analysis of a sample for its elemental abundances (XRF) and for the mineralogy of its iron-bearing phases (BaMS) without any sample preparation.

Agresti, D. G.; Wills, E. L.; Shelfer, T. D.; Pimperl, M. M.; Shen, Minghung; Morris, R. V.; Clark, B. C.; Ramsey, B. D.

1992-05-01

208

Extraterrestrial Mössbauer spectrometry  

NASA Astrophysics Data System (ADS)

We describe a combined backscatter Mössbauer spectrometer and X-ray fluorescence analyzer (BaMS/XRF) instrument suitable for planetary missions to the surfaces of Mars (MESUR Program), the Moon, asteroids, or other solid solar-system objects. The BaMS/XRF instrument is designed to be capable of concurrent analysis of a sample for its elemental abundances (XRF) and for the mineralogy of its iron-bearing phases (BaMS) without any sample preparation.

Agresti, David G.; Morris, Richard V.; Wills, Edward L.; Shelfer, Tad D.; Pimperl, Marsha M.; Shen, Ming-Hung; Clark, Benton C.; Ramsey, Brian D.

1992-05-01

209

Total Solar Irradiance Monitor for Chinese FY-3A and FY-3B Satellites - Instrument Design  

NASA Astrophysics Data System (ADS)

The Total Solar Irradiance Monitor (TSIM) instrument is designed to perform daily observations of total solar irradiance (TSI) in space on the Chinese FY-3A and FY-3B satellites. Three absolute radiometers are constructed for the TSIM to achieve measurements with traceability to SI with an absolute accuracy better than 550 ppm. The absolute radiometers are implemented based on the principle of electrical substitution. The design of the absolute radiometers and their electrical system, operation modes in space, and uncertainty evaluation are described. A method for calculating the electrical power in the observation and reference phases is proposed to maintain the primary cavity at a nearly constant temperature.

Fang, Wei; Wang, Hongrui; Li, Huiduan; Wang, Yupeng

2014-12-01

210

Ray tracing algorithm for accurate solar irradiance prediction in urban areas.  

PubMed

A ray tracing algorithm has been developed to model solar radiation interaction with complex urban environments and, in particular, its effects, including the total irradiance on each surface and overall dissipated power contribution. The proposed model accounts for multiple reflection and diffuse scattering interactions and is based on a rigorous theory, so that the overall power balance is satisfied at the generic surface element. Such approach is validated against measurements in the present work in simple reference scenarios. The results show the importance of multiple-bounce interactions and diffuse scattering to obtain reliable solar irradiance and heat dissipation estimates in urban areas. PMID:25321121

Vitucci, Enrico M; Falaschi, Federico; Degli-Esposti, Vittorio

2014-08-20

211

Solar irradiance from Nimbus-7 compared with ground-based photometry  

NASA Technical Reports Server (NTRS)

We have compared total solar irradiance from Nimbus-7 with ground-based photometry from the San Fernando Observatory (SFO) for 109 days between 1 June and 31 December, 1988. We have also included in some analyses NOAA-9 SBUV2 data or F10.7 radio flux. The Nimbus-7 data are from orbital samples, averaged to the mean time of observation at SFO. Using the same parameters as in Chapman et al. (1992), the multiple regression gives an R(exp 2) = 0.9131 and a 'solar minimum' irradiance, S(sub 0) = 1371.76 +/- 0.18 W/sq m for the best fit.

Chapman, G. A.; Cookson, A. M.; Hoyt, D. V.

1994-01-01

212

Making of solar irradiance composite records out of multiple observations (Invited)  

NASA Astrophysics Data System (ADS)

Reconstructing homogeneous spectral or total solar irradiance data sets from multiple incomplete records is a problem that poses major scientific and statistical challenges. Interestingly, this problem is also very similar to the ones that are encountered in the reconstruction of climate records from proxy data. Here, we focus on the reconstruction of a single MgII index and a single Total Solar Irradiance composite from instruments that overlap in time. This involves several steps: handling of data gaps, estimating the noise level of each instrument, properly addressing solar variability as observed at different time scales, and, finally, using a Bayesian approach for inferring a single composite, and its confidence interval. These steps will be detailed and currently favored approaches will be presented. As a last step, the composites will be confronted with model results. This work is currently being done in the framework of the FP7 SOLID project that aims at building a single solar spectral irradiance data set, and an international team at ISSI, which pursues the same objective, for the total solar irradiance.

Dudok de Wit, T.; Schoell, M.

2013-12-01

213

Development of irradiation methods and degradation modeling for state-of-the-art space solar cells  

NASA Astrophysics Data System (ADS)

Japan Atomic Energy Agency (JAEA) together with Japan Aerospace Exploration Agency (JAXA) has developed an insitu evaluation technique for understanding radiation response of space solar cells, by which the electrical characteristics of solar cells can be measured under AM0 light illumination during proton/electron irradiation experiments (Simultaneous method). Using the simultaneous method, we revealed the radiation degradation of multi-junction solar cells such as InGaP/GaAs/Ge triple junction (3J) solar cells. A modeling of the radiation degradation of 3J solar cells based on the Non-Ionizing Energy Loss (NIEL) concept was established. Flexible multi-junction solar cells are under development for space applications.

Ohshima, Takeshi; Sato, Shin-ichiro; Sumita, Taishi; Nakamura, Tetsuya; Imaizumi, Mitsuru

2014-06-01

214

Searching for extraterrestrial artifacts.  

NASA Astrophysics Data System (ADS)

The Fermi Paradox, attributed to a famous question from physicist Enrico Fermi in 1943, asks: if there are intelligent beings elsewhere then, in time, they must achieve the technology of nuclear power and space flight and would explore and colonize the Galaxy. Thus, they should have been able to travel to Earth, but we see no evidence of such visitations. Ergo, they cannot exist. The author, of the Xenology Research Institute in California, discusses this viewpoint and suggests how and where we might be able to detect an alien presence in the Solar System.

Freitas, R. A.

215

In Search of Sun-Climate Connection Using Solar Irradiance Measurements and Climate Records  

NASA Technical Reports Server (NTRS)

The Earth's temperature has risen approximately 0.5 degree-C in the last 150 years. Because the atmospheric concentration of carbon dioxide has increased nearly 30% since the industrial revolution, a common conjecture, supported by various climate models, is that anthropogenic greenhouse gases have contributed to global warming. Another probable factor for the warming is the natural variation of solar irradiance. Although the variation is as small as 0.1 % it is hypothesized that it contributes to part of the temperature rise. Warmer or cooler ocean temperature at one part of the Globe may manifest as abnormally wet or dry weather patterns some months or years later at another part of the globe. Furthermore, the lower atmosphere can be affected through its coupling with the stratosphere, after the stratospheric ozone absorbs the ultraviolet portion of the solar irradiance. In this paper, we use wavelet transforms based on Morlet wavelet to analyze the time-frequency properties in several datasets, including the Radiation Budget measurements, the long-term total solar irradiance time series, the long-term temperature at two locations for the North and the South Hemisphere. The main solar cycle, approximately 11 years, are identified in the long-term total solar irradiance time series. The wavelet transform of the temperature datasets show annual cycle but not the solar cycle. Some correlation is seen between the length of the solar cycle extracted from the wavelet transform and the North Hemisphere temperature time series. The absence of the 11-year cycle in a time series does not necessarily imply that the geophysical parameter is not affected by the solar cycle; rather it simply reflects the complex nature of the Earth's response to climate forcings.

Kiang, Richard K.; Kyle, H. Lee

2000-01-01

216

Continental aerosol properties inferred from measurements of direct and diffuse solar irradiance  

Microsoft Academic Search

Aerosol particles affect the global energy budget and Earth's climate through the absorption and scattering of both solar and terrestrial radiation. Here we present a study of column-averaged aerosol optical properties derived from clear-sky measurements of the direct and diffuse components of the solar downwelling spectral and broadband irradiance during a 10-day observation period at the Atmospheric Radiation Measurement (ARM)

David C. Marsden; Francisco P. J. Valero; Brett C. Bush

2005-01-01

217

Fenton degradation of 4-chlorophenol contaminated water promoted by solar irradiation  

Microsoft Academic Search

The degradation of 4-chlorophenol (4-CP) contaminated water by Fenton process with or without solar irradiation assistance were investigated. It was found that the COD degradation and mineralization efficiency of 4-CP were more than 90% when a 30min treatment of solar photo-Fenton oxidation process was applied and under an optimum [H2O2]0\\/[Fe2+]0 ratio of 40, the COD degradation and mineralization efficiency increased

Wen S. Kuo; Li N. Wu

2010-01-01

218

The Sun as a variable star: Solar and stellar irradiance variations; Colloquium of the International Astronomical Union, 143rd, Boulder, CO, Jun. 20-25, 1993  

NASA Technical Reports Server (NTRS)

Variations in solar and stellar irradiances have long been of interest. An International Astronomical Union (IAU) colloquium reviewed such relevant subjects as observations, theoretical interpretations, and empirical and physical models, with a special emphasis on climatic impact of solar irradiance variability. Specific topics discussed included: (1) General Reviews on Observations of Solar and Stellar Irradiance Variability; (2) Observational Programs for Solar and Stellar Irradiance Variability; (3) Variability of Solar and Stellar Irradiance Related to the Network, Active Regions (Sunspots and Plages), and Large-Scale Magnetic Structures; (4) Empirical Models of Solar Total and Spectral Irradiance Variability; (5) Solar and Stellar Oscillations, Irradiance Variations and their Interpretations; and (6) The Response of the Earth's Atmosphere to Solar Irradiance Variations and Sun-Climate Connections.

Pap, Judit M. (editor); Froehlich, Claus (editor); Hudson, Hugh S. (editor); Tobiska, W. Kent (editor)

1994-01-01

219

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

220

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

221

Influence of crystal tilt on solar irradiance of cirrus clouds.  

PubMed

The single and multiple scattering and absorption properties of hexagonal ice columns with different degrees of particle orientation are modeled in the solar spectral range by means of a ray-tracing single-scattering code and a Monte Carlo radiative-transfer code. The scattering properties are most sensitive to particle orientation for the solar zenith angles of 50 degrees (asymmetry parameter) and 90 degrees (single-scattering albedo). Provided that the ice columns are horizontally oriented, the usual assumption of random orientation leads to an overestimation (underestimation) of the reflected (transmitted) solar broadband radiation at high Sun elevation and to an underestimation (overestimation) at medium solar zenith angles. The orientation effect is more (less) pronounced in scattering and transmission (absorption) for smaller ice crystals. PMID:16512547

Klotzsche, Susann; Macke, Andreas

2006-02-10

222

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

223

Proposed reference irradiance spectra for solar energy systems testing  

Microsoft Academic Search

In 1982, the American Society for Testing and Materials (ASTM) adopted consensus standard solar terrestrial spectra (ASTM E891-82, E892-82) to provide standard spectra for photovoltaic (PV) performance applications. These spectra have been also used for other applications such as solar energy systems, fenestration, and materials degradation. These reference spectra were recomputed and the standards revised in 1987. The International Standards

C. A. Gueymard; D. Myers; K. Emery

2002-01-01

224

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

225

An Essay on Extraterrestrial Liberty  

NASA Astrophysics Data System (ADS)

The lethal environmental conditions in outer space and the surfaces of other planetary bodies will force a need for regulations to maintain safety to an extent hitherto not seen on the Earth, even in polar environments. The level of inter-dependence between individuals that will emerge will provide mechanisms for exerting substantial control. In extraterrestrial environ- ments traditional buffers to tyranny that exist on the Earth are either absent or much weaker. Legislative and political mechanisms used to protect freedom will be needed to such a degree that they themselves are likely to become a form of despotism. Thus, the most profound irony of the settlement of space is that the endless and apparently free expanses of interplanetary and interstellar space will in fact allow for, and nurture, some of the most appalling tyrannies that human society can contrive. Thwarting this tyranny will be the greatest social challenge in the successful establishment of extraterrestrial settlements.

Cockell, C. S.

226

Possible extraterrestrial strategy for earth  

NASA Astrophysics Data System (ADS)

A hypothesis concerning the nature of extraterrestrial messages to the earth is proposed. The hypothesis is based on the following assumptions about (1) that they exist in abundance in the Galaxy; (2) that they are benevolent toward earth-based life forms, and (3) that the lack of any human detection of extraterrestrials is due to an embargo designed to prevent any premature disclosure of their existence. It is argued that any embargo not involving alien force must be a leaky one designed to allow a gradual disclosure of the alien message and its gradual acceptance on the part of the general public over a very long time-scale. The communication may take the form of what is now considered magic, and may therefore be misinterpreted as 'magic' by or a hoax by contemporary governments and scientists.

Deardorff, J. W.

1986-03-01

227

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

228

The search for extraterrestrial intelligence  

Microsoft Academic Search

Suggested means of detecting extraterrestrial civilizations are examined. Such suggestions include the construction of a $10 billion, 25-square-mile radio receiver consisting of 1500 component antennas each 100 meters in diameter. Up to the present, 200 stars have been investigated for evidence of intelligent life; the author concedes that at least 200,000 stars would have to be probed to give us

Carl Sagan; Frank Drake

1975-01-01

229

Reconstruction of the solar EUV irradiance from 1996 to 2010 based on SOHO/EIT images  

NASA Astrophysics Data System (ADS)

The solar Extreme UltraViolet (EUV) spectrum has important effects on the Earth's upper atmosphere. For a detailed investigation of these effects it is important to have a consistent data series of the EUV spectral irradiance available. We present a reconstruction of the solar EUV irradiance based on SOHO/EIT images, along with synthetic spectra calculated using different coronal features which represent the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA2 tool which separates the features based on a fixed brightness classification scheme. With the SOLMOD code we then calculate intensity spectra for the 10-100 nm wavelength range and each of the coronal features. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed spectrum is then validated against the spectral irradiance as observed with SOHO/SEM. Our approach leads to good agreement between the reconstructed and the observed spectral irradiance. This study is an important step toward understanding variations in the solar EUV spectrum and ultimately its effect on the Earth's upper atmosphere.

Haberreiter, Margit; Delouille, Véronique; Mampaey, Benjamin; Verbeeck, Cis; Del Zanna, Giulio; Wieman, Seth

2014-10-01

230

THE USE OF MSG DATA WITHIN A NEW TYPE OF SOLAR IRRADIANCE CALCULATION SCHEME  

E-print Network

THE USE OF MSG DATA WITHIN A NEW TYPE OF SOLAR IRRADIANCE CALCULATION SCHEME R. W. Mueller , H Meteosat Second Generation (MSG) satellites. The expected quality represents a substantial improvement retrieved from the MSG satellite (clouds, ozone, water vapor) and the GOME/ATSR-2 satellites (aerosols

Heinemann, Detlev

231

Simultaneous retrievals of column ozone and aerosol optical properties from direct and diffuse solar irradiance measurements  

Microsoft Academic Search

A retrieval technique has been developed to simultaneously determine column ozone amounts and aerosol optical properties using surface observations of solar ultraviolet direct normal and diffuse horizontal irradiance from a multifilter rotating shadowband radiometer. The retrieval consists of a Bayesian scheme involving a tropospheric ultraviolet radiative transfer model. The technique was tested using cloud-free observations collected during a Mexico City

Christian D. Goering; Tristan S. L'Ecuyer; Graeme L. Stephens; James R. Slusser; Gwen Scott; John Davis; James C. Barnard; Sasha Madronich

2005-01-01

232

Stratospheric ozone response to a solar irradiance reduction in a quadrupled CO2 environment  

NASA Astrophysics Data System (ADS)

We used the Goddard Space Flight Center (GSFC) global two-dimensional (2D) atmospheric model to investigate the stratospheric ozone response to a proposed geoengineering activity wherein a reduced top-of-atmosphere (TOA) solar irradiance is imposed to help counteract a quadrupled CO2 atmosphere. This study is similar to the Geoengineering Model Intercomparison Project (GeoMIP) Experiment G1. Three primary simulations were completed with the GSFC 2D model to examine this possibility: (A) a pre-industrial atmosphere with a boundary condition of 285 ppmv CO2 (piControl); (B) a base future atmosphere with 1140 ppmv CO2 (abrupt4xCO2); and (C) a perturbed future atmosphere with 1140 ppmv CO2 and a 4% reduction in the TOA total solar irradiance (G1). We found huge ozone enhancements throughout most of the stratosphere (up to 40%) as a result of a large computed temperature decrease (up to 18 K) when CO2 was quadrupled (compare simulation abrupt4xCO2 to piControl). Further, we found that ozone will additionally increase (up to 5%) throughout most of the stratosphere with total ozone increases of 1-2.5% as a result of a reduction in TOA total solar irradiance (compare simulation G1 to abrupt4xCO2). Decreases of atomic oxygen and temperature are the main drivers of this computed ozone enhancement from a reduction in TOA total solar irradiance.

Jackman, Charles H.; Fleming, Eric L.

2014-07-01

233

Towards Building Reliable, High-Accuracy Solar Irradiance Database For Arid Climates  

NASA Astrophysics Data System (ADS)

Middle East's growing interest in renewable energy has led to increased activity in solar technology development with the recent commissioning of several utility-scale solar power projects and many other commercial installations across the Arabian Peninsula. The region, lying in a virtually rainless sunny belt with a typical daily average solar radiation exceeding 6 kWh/m2, is also one of the most promising candidates for solar energy deployment. However, it is not the availability of resource, but its characterization and reasonably accurate assessment that determines the application potential. Solar irradiance, magnitude and variability inclusive, is the key input in assessing the economic feasibility of a solar system. The accuracy of such data is of critical importance for realistic on-site performance estimates. This contribution aims to identify the key stages in developing a robust solar database for desert climate by focusing on the challenges that an arid environment presents to parameterization of solar irradiance attenuating factors. Adjustments are proposed based on the currently available resource assessment tools to produce high quality data for assessing bankability. Establishing and maintaining ground solar irradiance measurements is an expensive affair and fairly limited in time (recently operational) and space (fewer sites) in the Gulf region. Developers within solar technology industry, therefore, rely on solar radiation models and satellite-derived data for prompt resource assessment needs. It is imperative that such estimation tools are as accurate as possible. While purely empirical models have been widely researched and validated in the Arabian Peninsula's solar modeling history, they are known to be intrinsically site-specific. A primal step to modeling is an in-depth understanding of the region's climate, identifying the key players attenuating radiation and their appropriate characterization to determine solar irradiance. Physical approach based models and tools can subsequently be recalibrated or improvised to address the unique features of characteristically high aerosol load, frequent dust episodes and yet, typically clear skies, in the Gulf's primarily arid region. For example, though clouds are an important factor, radiative extinction in desert climates is primarily due to aerosols; a fact that needs to be taken into consideration since most of the existing solar radiation models are technically cloud-based. Satellite derived irradiance, although carrying a tag of uncertainties (5-10%), have special relevance in the Gulf due to lack of long-term data at the source of application. Satellite data can be merged or combined with short-term ground measurements, by various techniques available in the literature, to smooth out uncertainties in the data and build high-accuracy long-term solar irradiance profiles. Such concatenation is of particular interest to investors as it provides vital information on solar resource variability.

Munawwar, S.; Ghedira, H.

2012-12-01

234

Solar Irradiances Measured using SPN1 Radiometers: Uncertainties and Clues for Development  

SciTech Connect

The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, not only for the global component but also the diffuse and direct. End users look for the best compromise between getting close to state-of-the-art measurements and keeping capital, maintenance and operating costs to a minimum. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, which results from laboratory experiments, numerical modeling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the-art measurements.

Badosa, Jordi; Wood, John; Blanc, Philippe; Long, Charles N.; Vuilleumier, Laurent; Demengel, Dominique; Haeffelin, Martial

2014-12-08

235

Solar irradiances measured using SPN1 radiometers: uncertainties and clues for development  

NASA Astrophysics Data System (ADS)

The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, for not only the global but also the diffuse and direct components. End users look for the best compromise between getting close to state-of-the-art measurements and keeping low capital, maintenance and operating costs. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, drawing on laboratory experiments, numerical modelling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the art measurements.

Badosa, J.; Wood, J.; Blanc, P.; Long, C. N.; Vuilleumier, L.; Demengel, D.; Haeffelin, M.

2014-12-01

236

Solar irradiances measured using SPN1 radiometers: uncertainties and clues for development  

NASA Astrophysics Data System (ADS)

The fast development of solar radiation and energy applications, such as photovoltaic and solar thermodynamic systems, has increased the need for solar radiation measurement and monitoring, not only for the global component but also for the diffuse and direct. End users look for the best compromise between getting close to state-of-the-art measurements and keeping low capital, maintenance and operating costs. Among the existing commercial options, SPN1 is a relatively low cost solar radiometer that estimates global and diffuse solar irradiances from seven thermopile sensors under a shading mask and without moving parts. This work presents a comprehensive study of SPN1 accuracy and sources of uncertainty, which results from laboratory experiments, numerical modeling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the art measurements.

Badosa, J.; Wood, J.; Blanc, P.; Long, C. N.; Vuilleumier, L.; Demengel, D.; Haeffelin, M.

2014-08-01

237

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

238

Modeling Effects of Vegetation and Topography on Subcanopy Solar Irradiance using Waveform Lidar  

NASA Astrophysics Data System (ADS)

Topography and canopy structure significantly affect the spatial variability of subcanopy surface solar radiation but have not been widely incorporated in radiation balance estimates due to limited information on vertical canopy structures and requirements for intensive ground based data collection. In this particular research work, we discuss the development of a 3-D model by integrating these two factors. Medium footprint waveform Lidar data from Laser Vegetation Imaging Sensor (LVIS) collected in 2008 over Sierra National Forest, California is used as input for the model. The 3-D model is based on radiative transfer principles and ray tracing techniques to estimate subcanopy surface solar irradiance. Light transmittance value is estimated for each of the canopy voxels. Transmittance at various solar positions is then converted into irradiance given, direct and diffuse components of irradiance at top of the canopy. To accommodate the effects of topography, the rays are traced from the surface towards the sun and the lower limit of horizon is calculated using the surface DEM. The study is expected to increase knowledge on topographic and vegetation effects on sub-canopy surface solar radiation. The resulting solar radiation maps can be used to improve the outcome of many physical based and ecological models.

Anand, A.; Dubayah, R.; Hofton, M. A.

2011-12-01

239

Total solar irradiance reconstruction since 1700 using a flux transport model  

NASA Astrophysics Data System (ADS)

Reconstructions of solar irradiance into the past are crucial for studies of solar influence on climate. Models based on the assumption that irradiance changes are caused by the evolution of the photospheric magnetic fields have been most successful in reproducing the measured irradiance variations. Daily magnetograms, such as those from MDI and HMI, provide the most detailed information on the changing distribution of the photospheric magnetic fields. Since such magnetograms are only available from 1974, we used a surface flux transport model to describe the evolution of the magnetic fields on the solar surface due to the effects of differential rotation, meridional circulation, and turbulent diffusivity, before 1974. In this model, the sources of magnetic flux are the active regions, which are introduced based on sunspot group areas, positions, and tilt angles. The RGO record is, however, only available since 1874. Here we present a model of solar irradiance since 1700, which is based on a semi-synthetic sunspot record. The semi-synthetic record was obtained using statistical relationships between sunspot group properties (areas, positions, tilt angles) derived from the RGO record on one hand, and the cycle strength and phase derived from the sunspot group number (Rg) on the other. These relationships were employed to produce daily records of sunspot group positions, areas, and tilt angles before 1874. The semi-synthetic records were fed into the surface flux transport model to simulate daily magnetograms since 1700. By combining the simulated magnetograms with a SATIRE-type model, we then reconstructed total solar irradiance since 1700.

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

240

An Alternative Derivation of the Nimbus 7 Total Solar Irradiance Variations  

NASA Technical Reports Server (NTRS)

Nimbus 7 solar irradiance values have been made available to the scientific community through the open literature (e.g., Hickey et al., 1988) and through NASA data centers. A comparison of these measurements to the Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor (SSM/ACRIM) time series indicated differences which might be caused in part by the method of converting the Nimbus 7 raw data counts to solar irradiance values. In an effort to see if the derivation of the solar irradiance could be improved, the raw counts were extracted from the tapes and analyzed to see how a new algorithm could be constructed. The basic form of the calibration remains the same as in the previous solar irradiance derivations. However, the input values to the equation differ from what was used before. In particular, improved values of the Earth-sun distance are incorporated and new temperature sensitivities were derived. Several problems with the instrument were uncovered which previously had not been noticed. The sun did not appear to cross the center of field of the radiometer but was systematically off by 1.5 to 2.5 degrees. The analog to digital convertor changed its properties in July 1980. The gain of the electronics apparently increased by 0.03 percent in September 1987. Applying these and other changes in the processing, the day to day variations appear much more like the SMM observations. In fact, the Nimbus 7 observations are sufficiently stable that a problem with the SSM observations in the spin mode period of 1981 to 1984 can be detected when the two time series are compared.

Hoyt, Douglas V.; Kyle, H. Lee

1990-01-01

241

Intercomparison of SCIAMACHY and SIM vis-IR irradiance over several solar rotational timescales  

NASA Astrophysics Data System (ADS)

The two satellite spectrometers SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) aboard ENVISAT (Environmental Satellite), and SIM (Spectral Irradiance Monitor) aboard SORCE (Solar Radiation and Climate Experiment) observe since 2002 and 2003, respectively, daily solar spectral irradiance (SSI) not only in UV but extending to the visible and near- infrared (vis-NIR) regions. In this work, we intercompare (1) spectra and (2) timeseries of SSI measurements from SCIAMACHY and SIM. In (1) same-day (April 21, 2004) SSI measurements from these two instruments are compared to reference spectra from ground (new Kurucz), high-altitude (Hall and Anderson, Neckel and Labs, and Wehrli composite), and space (SOLSPEC/ATLAS 3, and SUSIM/UARS). In (2) timeseries of measurements (July 3 to August 21, 2004) covering several solar rotations in 2004 are compared to VIRGO sunphotometers (SPM) aboard SOHO. In general, SCIAMACHY and SIM are in agreement to within 4% over the common spectral domain and with respect to the other reference data. Apart from SSI and its variability, we integrate SSI over selected wavelength intervals and compare qualitatively to total solar irradiance (TSI) variability from PMOD/WRC and TIM/SORCE. Timeseries of integrated SSI in the vis (400-700 nm), NIR (700-1600 nm), and UV-vis-NIR (240-1600 nm) bands are compared. The overall rise and fall of integrated SCIAMACHY and SIM irradiances over several solar rotations are in good agreement and agree in most cases qualitatively with TSI variations in the visible and near IR. The application of White Light Source (WLS) corrections brings SCIAMACHY irradiances in closer agreement with SIM. Since WLS is also degrading with time, the WLS lamp ratios cannot be used for SSI degradation corrections after 2004.

Pagaran, J.; Harder, J. W.; Weber, M.; Floyd, L. E.; Burrows, J. P.

2011-04-01

242

A Program of Photometric Measurements of Solar Irradiance Fluctuations from Ground-based Observations  

NASA Technical Reports Server (NTRS)

Photometric observations of the sun have been carried out at the San Fernando Observatory since early 1985. Since 1986, observations have been obtained at two wavelengths in order to separately measure the contributions of sunspots and bright facular to solar irradiance variations. Researchers believe that the contributions of sunspots can be measured to an accuracy of about plus or minus 30 ppm. The effect of faculae is much less certain, with uncertainties in the range of plus or minus 300 ppm. The larger uncertainty for faculae reflects both the greater difficulty in measuring the facular area, due to their lower contrast compared to sunspots, and the greater uncertainty in their contrast variation with viewing angle on the solar disk. Recent results from two separate photometric telescopes will be compared with bolometric observations from the active cavity radiometer irradiance monitor (ACRIM) that was on board the Solar Max satellite.

Chapman, G. A.; Herzog, A. D.; Lawrence, J. K.; Walton, S. R.

1990-01-01

243

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

244

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

NASA Astrophysics Data System (ADS)

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 which the cell degradation under any energy proton irradiation can be calculated. The data measured under 1 MeV electron irradiation is also analyzed in terms of displacement damage dose. The electron irradiation-induced degradation is correlated with the proton degradation curve by determining electron to proton dose ratios for each of the photovoltaic (PV) parameters. A comparison of the characteristic degradation curves for InP and GaAs/Ge solar cells, which was determined previously, shows InP to be intrinsically more resistant to displacement energy deposition. The base carrier concentration was measured during the irradiations, and significant carrier removal was observed. When analyzed as a function of displacement damage dose, the reduction in carrier concentration under both the 1 MeV electron and the 3 MeV proton irradiation is shown to follow the same degradation curve. From this common degradation curve, a characteristic carrier removal rate is calculated for InP under any irradiation. The junction dark current was also measured during both irradiations, and the data were fit to a three-term diode dark current equation. From the fits, the diffusion current is determined as a function of particle fluence. Changes in the diffusion current under electron and proton irradiation are shown to correlate in terms of displacement damage dose in the same way as the cell maximum power. The junction recombination current is also determined from the dark current data, and the results show the energy level of the dominant radiation-induced recombination center to be approximately the same in both the electron and proton irradiated samples. In addition, the dark current analysis indicates that the relative changes in the hole and electron lifetimes are essentially the same under both the electron and the proton irradiations. Based on these results and the overall correlation between the electron and proton damage, a detailed description of the mechanism of the radiation response of InP is developed which describes the cell degradation under any particle irradiation.

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

1996-06-01

245

Modelling solar irradiances using ground-based measurements  

NASA Technical Reports Server (NTRS)

The first results of photometric measurements of Ca-K plage remnants are presented. They show that during the fall of 1986 the remnants gave a significant contribution to the irradiance variations and that the averaged remnant component is less than assumed in the present UV models. The contribution of the plage remnants to the combined plage and remnant index was on average about 13 percent, and it changed with time.

Pap, J. M.; Marquette, W. H.; Donnelly, R. F.

1991-01-01

246

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

247

Evaluation of errors made in solar irradiance estimation due to averaging the Angstrom turbidity coefficient  

NASA Astrophysics Data System (ADS)

Even though the monitoring of solar radiation experienced a vast progress in the recent years both in terms of expanding the measurement networks and increasing the data quality, the number of stations is still too small to achieve accurate global coverage. Alternatively, various models for estimating solar radiation are exploited in many applications. Choosing a model is often limited by the availability of the meteorological parameters required for its running. In many cases the current values of the parameters are replaced with daily, monthly or even yearly average values. This paper deals with the evaluation of the error made in estimating global solar irradiance by using an average value of the Angstrom turbidity coefficient instead of its current value. A simple equation relating the relative variation of the global solar irradiance and the relative variation of the Angstrom turbidity coefficient is established. The theoretical result is complemented by a quantitative assessment of the errors made when hourly, daily, monthly or yearly average values of the Angstrom turbidity coefficient are used at the entry of a parametric solar irradiance model. The study was conducted with data recorded in 2012 at two AERONET stations in Romania. It is shown that the relative errors in estimating global solar irradiance (GHI) due to inadequate consideration of Angstrom turbidity coefficient may be very high, even exceeding 20%. However, when an hourly or a daily average value is used instead of the current value of the Angstrom turbidity coefficient, the relative errors are acceptably small, in general less than 5%. All results prove that in order to correctly reproduce GHI for various particular aerosol loadings of the atmosphere, the parametric models should rely on hourly or daily Angstrom turbidity coefficient values rather than on the more usual monthly or yearly average data, if currently measured data is not available.

Calinoiu, Delia-Gabriela; Stefu, Nicoleta; Paulescu, Marius; Trif-Tordai, Gavril?; Mares, Oana; Paulescu, Eugenia; Boata, Remus; Pop, Nicolina; Pacurar, Angel

2014-12-01

248

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

249

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

250

A new relation between the central spectral solar H I Lyman ? irradiance and the line irradiance measured by SUMER\\/SOHO during the cycle 23  

Microsoft Academic Search

The spectral irradiance at the center of the solar H I Lyman ? (?0=121.5664nm, referred to as Ly? in this paper) line profile is the main excitation source responsible for the atomic hydrogen resonant scattering of cool material in our Solar System. It has therefore to be known with the best possible accuracy in order to model the various Ly?

Claude Emerich; Philippe Lemaire; Jean-Claude Vial; Werner Curdt; Udo Schühle; Klaus Wilhelm

2005-01-01

251

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.

252

Report on the Workshop on Intercomparison of Solar UV Irradiance Measurements and Related Instrument Calibration  

NASA Technical Reports Server (NTRS)

The knowledge of the absolute value of the solar ultraviolet irradiance did not improve very much during the rising phase of the solar cycle 21. The variations associated with the solar rotation period were observed by means of three satellites, namely, the Atmospheric Explorer E (AE-E), Nimbus 7 and the Solar Mesospheric Explorer (SME). Long-term variations related to the solar activity cycle are not well known. Values were deduced during the solar cycle 21 from the AE-E satellite and the rocket program performed by the Laboratory for Atmospheric and Space Physics leading to variations of about a factor of 2 around 150 nm but definitely less than 20 percent beyond 175 nm. Such low level of variation is still masked by the current uncertainties and reproducibility of the observations performed since 1976. The uncertainties of recent observations are reported with their discrepancies. The gaps between the current accuracy goals and the achievements are still very important. The challenge for the next three years is to improve both the accuracy and the precision of future observations at the level of the available irradiance standards and to measure quantitatively long-term variations of the order of a few percent. The main causes of these gaps are identified.

Simon, P. C.

1983-01-01

253

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

254

Measurements of solar ultraviolet irradiance with respect to the human body surface  

NASA Astrophysics Data System (ADS)

Solar UV irradiance is measured in Westerland, Germany (54.9 degree(s) N, 8.3 degree(s) E) in the immediate vicinity of the North Sea shoreline. Measurements have been done since July 1993, focussing on the biologically effective UV radiation and the human body geometry. A grid double monochromator radiometer (DM 150, Bentham Instruments Comp., Reading, England) is used to measure the spectral resolution of 1 nm. Weighting the spectral irradiance by the action spectrum for the erythema is more appropriate for determining the biological effectiveness than simply dividing the UV radiation into the UV-A and UV-B wavebands. The erythemal irradiance shows a close relation to the sun angle during the course of a day. The exposure times, calculated from the irradiance and the minimal erythemal doses, suggest that people might underestimate the risk of getting sunburnt before noon. Diffuse radiation scattered from the sky contribute about 70% of the erythemal irradiance at a 45 degree(s) sun angle. A receiver oriented directly to the sun, i.e. 45 degree(s) inclined, receives an additional 30% of the erythemal irradiance measured by a horizontally adjusted cosine response sensor. The relative irradiance of curved surfaces like the skin is determined by UV- B-sensitive paper placed around a cylinder. This device detected UV radiation reflected by the sea, which hardly is measured by horizontally adjusted receivers.

Stick, Carsten; Harms, Volker; Pielke, Liane

1994-07-01

255

Intercomparison of spectroradiometers for solar spectral irradiance measurements preliminary results  

NASA Astrophysics Data System (ADS)

This paper describes the preliminary results of an intercomparison of spectroradiometers for direct (DNI) and global normal incidence (GNI) irradiance in the visible (VIS) and near infrared (NIR) region. Seven institutions and six spectroradiometers, representing different technologies and manufacturers were involved. All instruments were able to measure GNI; a restricted sub-group of four instruments had the possibility to also measure DNI when equipped with proper collimators. Prior to the intercomparison, all participating institutions calibrated their own instrument(s) according to their usual procedures in order to verify the entire calibration and traceability chain.

Galleano, R.; Zaaiman, W.; Morabito, P.; Minuto, A.; Spena, A.; Bartocci, S.; Fucci, R.; Leanza, G.; Pavanello, D.; Virtuani, A.; Fasanaro, D.; Catena, M.; Norton, M.

2012-10-01

256

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

257

Solar Irradiance Variability and Its Impacts on the Earth Climate System  

NASA Astrophysics Data System (ADS)

The Sun plays a vital role in the evolution of the climates of terrestrial planets. Observations of the solar spectrum are now routinely made that span the wavelength range from the X-ray portion of the spectrum (5 nm) into the infrared to about 2400 nm. Over this very broad wavelength range, accounting for about 97% of the total solar irradiance, the intensity varies by more than 6 orders of magnitude, requiring a suite of very different and innovative instruments to determine both the spectral irradiance and its variability. The origins of solar variability are strongly linked to surface magnetic field changes, and analysis of solar images and magnetograms show that the intensity of emitted radiation from solar surface features in active regions has a very strong wavelength and magnetic field strength dependence. These magnetic fields produce observable solar surface features such as sunspots, faculae, and network structures that contribute in different ways to the radiated output. Semi-empirical models of solar spectral irradiance are able to capture much of the Sun's output, but this topic remains an active area of research. Studies of solar structures in both high spectral and spatial resolution are refining this understanding. Advances in Earth observation systems and high-quality three-dimensional chemical climate models provide a sound methodology to study the mechanisms of the interaction between Earth's atmosphere and the incoming solar radiation. Energetic photons have a profound effect on the chemistry and dynamics of the thermosphere and ionosphere, and these processes are now well represented in upper atmospheric models. In the middle and lower atmosphere the effects of solar variability enter the climate system through two nonexclusive pathways referred to as the top-down and bottom-up mechanisms. The top-down mechanism proceeds through the alteration of the photochemical rates that establish the middle atmospheric temperature structure and circulation patterns. In the bottom-up mechanism, the increased solar cycle forcing at Earth's surface increases the latent heat flux and evaporation processes, thereby altering the tropical wind patterns.

Harder, J. W.; Woods, T. N.

258

How does ionospheric TEC vary if solar EUV irradiance continuously decreases?  

NASA Astrophysics Data System (ADS)

It is an interesting topic how the ionosphere varies when solar extreme ultraviolet (EUV) irradiance decreases far below normal levels. When extrapolating the total electron content (TEC)-EUV relation, significantly negative TECs at the zero solar EUV point are obtained, which indicates that TEC-EUV variation under extremely low solar EUV (ELSE) conditions does not follow the TEC-EUV trend during normal solar cycles. We suggest that there are four types of nonlinear TEC-EUV variations over the whole EUV range from zero to the solar maximum level. The features of the ionosphere under ELSE conditions were investigated using the TEC extrapolated with cubic TEC-EUV fitting. With the constraint of zero TEC at zero EUV, the cubic fitting takes not only observations but also the trend of the ionosphere (only an extremely weak ionosphere can exist when EUV vanishes) into account. The climatology features of TEC under ELSE conditions may differ from those during normal solar cycles at nighttime. Ionospheric dynamic processes are supposed to still significantly affect the ionosphere under ELSE conditions and induce this difference. With solar EUV decreasing, global electron content (GEC) should vary largely in accordance with the GEC-EUV trend during normal solar cycles, and the seasonal fluctuation of GEC declines, owing to the contraction of the ionosphere.

Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

2014-12-01

259

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

260

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

261

Searching for extra-terrestrial civilizations  

NASA Technical Reports Server (NTRS)

The probability of radio interchange with extraterrestrial civilizations is discussed. Difficulties constitute absorption, scattering, and dispersion of signals by the rarified interstellar medium as well as the deciphering of received signals and convergence of semantic concept. A cybernetic approach considers searching for signals that develop from astroengineering activities of extraterrestrial civilizations.

Gindilis, L. M.

1974-01-01

262

Searching for extraterrestrial intelligence - The ultimate exploration  

Microsoft Academic Search

A survey highlighting the central issues of the SETI program (Search for Extraterrestrial Intelligence), including its rationale, scope, search problems, and goals is presented. Electromagnetic radiation is suggested as the most likely means via which knowledge of extraterrestrial intelligence will be obtained, and the variables governing these signals are discussed, including: signal frequency and polarization, state, possible coordinates, and signal

D. Black; J. Tarter; J. N. Cuzzi; M. Conners; T. A. Clark

1977-01-01

263

The Search for Extraterrestrial Intelligence, SETI  

Microsoft Academic Search

Findings are presented of a series of workshops on the existence of extraterrestrial intelligent life and ways in which extraterrestrial intelligence might be detected. The coverage includes the cosmic and cultural evolutions, search strategies, detection of other planetary systems, alternate methods of communication, and radio frequency interference. 17 references. (JFP)

Philip Morrison; John Billingham; John Wolfe

1977-01-01

264

SAS Honors Seminar 259: Extraterrestrial Life  

E-print Network

of the assignment? #12; Reading for Wednesday (11/12) Bennett & Shostak 12.3 ­ SETI (Search for Extraterrestrial Intelligence) Alexander & Anderson (2007) and Alexander (2008): SETI@home and a new search strategy #12 SAS Honors Seminar 259: Extraterrestrial Life 11/10/2008 #12; GBT remote observing

Baker, Andrew J.

265

The search for extraterrestrial intelligence: Telecommunications technology  

Microsoft Academic Search

Efforts to discover evidence of intelligent extraterrestrial life have become not only feasible, but respectable. Fledgling observational projects have begun that will use stateof-the-art hardware to develop sophisticated receiving and data processing systems. The rationale behind the Search for Extraterrestrial Intelligence (SETI), the manner in which the program is taking shape, and the implications for telecommunications are described. We conclude

R. Edelson; G. Levy

1977-01-01

266

The search for extraterrestrial intelligence: Telecommunications technology  

Microsoft Academic Search

Efforts to discover evidence of intelligent extraterrestrial life have become not only feasible, but respectable. Fledgling observational projects have begun that will use state-of-the-art hardware to develop sophisticated receiving and data processing systems. The rationale behind the Search for Extraterrestrial Intelligence, the manner in which the program is taking shape, and the implications for telecommunications are described. It is concluded

R. E. Edelson; G. S. Levy

1980-01-01

267

The Search for Extraterrestrial Intelligence (SETI)  

Microsoft Academic Search

The search for evidence of extraterrestrial intelligence is placed in the broader astronomical context of the search for extrasolar planets and biomarkers of primitive life elsewhere in the universe. A decision tree of possible search strategies is presented as well as a brief history of the search for extraterrestrial intelligence (SETI) projects since 1960. The characteristics of 14 SETI projects

Jill Tarter

2001-01-01

268

The Search for Extraterrestrial Intelligence (SETI)  

Microsoft Academic Search

A brief review is presented of the hypotheses inherent in searches for extraterrestrial intelligence (SETI). Some of the problems associated with such work at radio wavelengths are discussed, such as the optimal choice of a search frequency. It is shown that pulsed laser signals sent from an extraterrestrial civilisation should be observed to be brighter than the parent star, even

F. P. Keenan; M. E. Phillips; S. J. Rose; D. D. Burgess

1999-01-01

269

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

/15) Bennett & Shostak 12.3 ­ SETI (Search for Extraterrestrial Intelligence) Alexander & Anderson (2007 SAS Honors Seminar 256: Extraterrestrial Life 11/10/2011 #12; Results: Mars vs. Europa vs), Alexander (2008, 2009): SETI@home, a new search strategy, and SERENDIP V Blair (2009) & Pierson (2011

Baker, Andrew J.

270

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

271

Solar irradiance variability: a six-year comparison between SORCE observations and the SATIRE model  

NASA Astrophysics Data System (ADS)

Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total solar irradiance and broken down into spectral regions on timescales of several years. Methods: We use the SATIRE model and compare modeled total solar irradiance (TSI) with TSI measurements over the period 25 February 2003 to 1 November 2009. Spectral solar irradiance over 200-1630 nm is compared with the SIM instrument on SORCE over the period 21 April 2004 to 1 November 2009. We discuss the overall change in flux and the rotational and long-term trends during this period of decline from moderate activity to the recent solar minimum in ~10 nm bands and for three spectral regions of significant interest: the UV integrated over 200-300 nm, the visible over 400-691 nm and the IR between 972-1630 nm. Results: The model captures 97% of the observed TSI variation. This is on the order at which TSI detectors agree with each other during the period considered. In the spectral comparison, rotational variability is well reproduced, especially between 400 and 1200 nm. The magnitude of change in the long-term trends is many times larger in SIM at almost all wavelengths while trends in SIM oppose SATIRE in the visible between 500 and 700 nm and again between 1000 and 1200 nm. We discuss the remaining issues with both SIM data and the identified limits of the model, particularly with the way facular contributions are dealt with, the limit of flux identification in MDI magnetograms during solar minimum and the model atmospheres in the IR employed by SATIRE. However, it is unlikely that improvements in these areas will significantly enhance the agreement in the long-term trends. This disagreement implies that some mechanism other than surface magnetism is causing SSI variations, in particular between 2004 and 2006, if the SIM data are correct. Since SATIRE was able to reproduce UV irradiance between 1991 and 2002 from UARS, either the solar mechanism for SSI variation fundamentally changed around the peak of cycle 23, or there is an inconsistency between UARS and SORCE UV measurements. We favour the second explanation.

Ball, W. T.; Unruh, Y. C.; Krivova, N. A.; Solanki, S.; Harder, J. W.

2011-06-01

272

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

273

Total Solar Irradiance Monitor for the FY-3B Satellite - Space Experiments and Primary Data Corrections  

NASA Astrophysics Data System (ADS)

We present space experiments of the Total Solar Irradiance Monitor (TSIM) on the FY-3B satellite. The total solar irradiance (TSI) has been measured by TSIM/FY-3B continuously for nearly four years, with some short data gaps. Overlapping measurements of the TSI are provided by the TSIM, with three electrical substitution radiometers that are mounted with different alignment angles onto the leading face of the satellite. TSI measurements are normalized to a distance of 1 AU and zero velocity with respect to the Sun. The relative uncertainty in the TSI measurements is 910 parts per million. TSI values measured with TSIM/FY-3B are around 1365 W m-2, slightly lower than VIRGO/SOHO and higher than TIM/SORCE values. Most of the time, it is found that short time-scale variations in TSI detected by TSIM/FY-3B agree with other space TSI instruments.

Wang, Hongrui; Li, Huiduan; Qi, Jin; Fang, Wei

2015-02-01

274

Solar irradiance changes and photobiological effects at Earth's surface following astrophysical ionizing radiation events  

E-print Network

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the TUV radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radi...

Thomas, Brian C; Snyder, Brock R

2015-01-01

275

High intensity solar irradiation testing of UV optics. [OSO-8 instruments  

NASA Technical Reports Server (NTRS)

The Orbiting Solar Observatory-I (OSO-8 in orbit) incorporates two high resolution solar pointing spectrometers operating from 1000 A to 4000 A. Energy from the sun enters a Cassegrainian telescope and is focused on a slit while the solar disk is scanned to one arc-second resolution. The stability of the secondary mirrors reflectance was of concern since they would be exposed to intense focused solar energy up to 27 suns. A test program was initiated to simulate this energy input on sample UV mirrors of the MgF2 and LiF types and to evaluate their performance after irradiation. Tests were conducted to simulate the solar spectrum at high intensities (25 suns) and at a single wavelength near Lyman-alpha, but with twenty times the solar intensity at Lyman-alpha. Post-test measurements after every exposure were made at wavelengths from 1025 A to 1849 A. After 75 simulated 'orbits', reflectance changes due to temperature effects were noted to be less than 10%. Reductions in reflectance under high intensity solar radiation were generally greater than 10%. Polymerization of surface contaminations on the LiF mirrors reduced reflectances at short wavelengths by 40%.

Greyerbiehl, J. M.; Oberright, J. E.

1976-01-01

276

Radiative Heat Transfer Analysis within Three-Dimensional Clouds Subjected to Solar and Sky Irradiation  

Microsoft Academic Search

A three-dimensional radiative heat transfer analysis of an arbitrary-shaped modeled cloud subjected to solar and sky irradiation has been performed. The Radiation Element Method by Ray Emission Model (REM2) was used for numerical simulation. Nongray, anisotropic scattering, absorbing, and emitting are taken into account in calculating the three-dimensional cloud. The modeled cloud is considered to be a low-level fair-weather cumulus

Toru Nishikawa; Shigenao Maruyama; Seigo Sakai

2004-01-01

277

Response of prostaglandin content in the red alga Gracilaria verrucosa to season and solar irradiance  

Microsoft Academic Search

The influence of solar irradiance and seasons on prostaglandin (PG) and arachidonic acid (AA) content in the marine red alga Gracilaria verrucosa (Huds.) Papenf. (unattached form) was investigated. PGA2, PGE2, PGF2, and 15-keto-PGE2 were isolated from the alga, quantitatively analyzed as 4-methyl-7-methoxycoumarin esters by high-performance liquid chromatography, and their chemical structures were confirmed by 1H NMR. In June–September, the PG

Andrey B Imbs; Anna V Vologodskaya; Natalia V Nevshupova; Svetlana V Khotimchenko; Edouard A Titlyanov

2001-01-01

278

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

279

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

280

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

281

Photoluminescence study of silicon solar cells irradiated with large fluence electrons or protons  

NASA Astrophysics Data System (ADS)

In order to investigate the anomalous degradation of space silicon solar cells which was found in large fluence region, photoluminescence measurements are carried out for the cells irradiated with 1 MeV electrons with a fluence exceeding 1×10 16 e/cm 2 and 10 MeV protons with a fluence exceeding 1×10 13 p/cm 2. For both irradiation, the intensity of boron-related bound exiton line decreases with fluence and it disappears at the fluences where the anomalous degradation occurs. The dominant defect is a complex of an interstitial carbon and an interstitial oxygen (C I-O I). The generation of five-vacancy-defects was also observed for the proton irradiation. Variations of photoluminescence line intensity are discussed in terms of displacement damage dose calculated based on non-ionizing energy loss (NIEL).

Hisamatsu, Tadashi; Kawasaki, Osamu; Matsuda, Sumio; Tsukamoto, Kazuyoshi

1999-01-01

282

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

283

Extraterrestrials  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on our attempts to reach intelligent life by sending messages into space. Students look at a visual of the message that has been sent from the Arecibo radio dish in Puerto Rico, and discuss what it means and the possibility of getting a reply. It includes objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

284

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

285

Solar Irradiance Changes and Photobiological Effects at Earth's Surface Following Astrophysical Ionizing Radiation Events  

NASA Astrophysics Data System (ADS)

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the TUV radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events.

Thomas, Brian C.; Neale, Patrick J.; Snyder, Brock R., II

2015-03-01

286

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

287

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

SciTech Connect

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, R.J.; Summers, G.P.; Messenger, S.R.; Burke, E.A. [SFA, Inc., Landover, MD (United States)

1995-10-01

288

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

NASA Astrophysics Data System (ADS)

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.

1995-10-01

289

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

290

I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar cells  

E-print Network

Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV lithium ions. Dark-IV analysis (with and without illumination) reveals differences in the effects of such irradiation on the different cell types

A. Meulenberg Jr; B. Jayashree; Ramani; M. C. Radhakrishna; A. K. Saif

2007-09-07

291

Degradation modeling of InGaP/GaAs/Ge triple-junction solar cells irradiated by protons  

NASA Astrophysics Data System (ADS)

Experimental results on triple-junction solar cells irradiated by 3 MeV proton irradiation to very high damage levels are presented. The minority carrier transport properties were obtained through quantum efficiency and EBIC measurements and an analytical drift-diffusion solver was used in understanding the results for different degradation levels where multiple damage mechanisms are evident.

Maximenko, S. I.; Lumb, M. P.; Messenger, S. R.; Hoheisel, R.; Affouda, C.; Scheiman, D.; Gonzalez, M.; Lorentzen, J.; Jenkins, P. P.; Walters, R. J.

2014-03-01

292

Modeling of biomass productivity in tubular photobioreactors for microalgal cultures: Effects of dilution rate, tube diameter, and solar irradiance  

Microsoft Academic Search

A macromodel is developed for estimating the year-long biomass productivity of outdoor cultures of microalga in tubular photobioreactors. The model evalu- ates the solar irradiance on the culture surface as a func- tion of day of the year and the geographic location. In a second step, the geometry of the system is taken into account in estimating the average irradiance

F. G. Acién Fernández; F. García Camacho; J. A. Sánchez Pérez; J. M. Fernández Sevilla; E. Molina Grima

1998-01-01

293

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

294

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.

295

A new method for assessing surface solar irradiance: Heliosat-4  

NASA Astrophysics Data System (ADS)

Downwelling shortwave irradiance at surface (SSI) is more and more often assessed by means of satellite-derived estimates of optical properties of the atmosphere. Performances are judged satisfactory for the time being but there is an increasing need for the assessment of the direct and diffuse components of the SSI. MINES ParisTech and the German Aerospace Center (DLR) are currently developing the Heliosat-4 method to assess the SSI and its components in a more accurate way than current practices. This method is composed by two parts: a clear sky module based on the radiative transfer model libRadtran, and a cloud-ground module using two-stream and delta-Eddington approximations for clouds and a database of ground albedo. Advanced products derived from geostationary satellites and recent Earth Observation missions are the inputs of the Heliosat-4 method. Such products are: cloud optical depth, cloud phase, cloud type and cloud coverage from APOLLO of DLR, aerosol optical depth, aerosol type, water vapor in clear-sky, ozone from MACC products (FP7), and ground albedo from MODIS of NASA. In this communication, we briefly present Heliosat-4 and focus on its performances. The results of Heliosat-4 for the period 2004-2010 will be compared to the measurements made in five stations within the Baseline Surface Radiation Network. Extensive statistic analysis as well as case studies are performed in order to better understand Heliosat-4 and have an in-depth view of the performance of Heliosat-4, to understand its advantages comparing to existing methods and to identify its defaults for future improvements. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 218793 (MACC project) and no. 283576 (MACC-II project).

Qu, Z.; Oumbe, A.; Blanc, P.; Lefèvre, M.; Wald, L.; Schroedter-Homscheidt, M.; Gesell, G.

2012-04-01

296

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

297

Modeling Total Solar Irradiance Variations Using Automated Classification Software on Mount Wilson Data  

NASA Astrophysics Data System (ADS)

We present the results using the AutoClass analysis application available at NASA/Ames Intelligent Systems Div. (2002) which is a Bayesian, finite mixture model classification system developed by Cheeseman and Stutz (1996). We apply this system to Mount Wilson Solar Observatory (MWO) intensity and magnetogram images and classify individual pixels on the solar surface to calculate daily indices that are then correlated with total solar irradiance (TSI) to yield a set of regression coefficients. This approach allows us to model the TSI with a correlation of better than 0.96 for the period 1996 to 2007. These regression coefficients applied to classified pixels on the observed solar surface allow the construction of images of the Sun as it would be seen by TSI measuring instruments like the Solar Bolometric Imager recently flown by Foukal et al. ( Astrophys. J. 611, L57, 2004). As a consequence of the very high correlation we achieve in reproducing the TSI record, our approach holds out the possibility of creating an on-going, accurate, independent estimate of TSI variations from ground-based observations which could be used to compare, and identify the sources of disagreement among, TSI observations from the various satellite instruments and to fill in gaps in the satellite record. Further, our spatially-resolved images should assist in characterizing the particular solar surface regions associated with TSI variations. Also, since the particular set of MWO data on which this analysis is based is available on a daily basis back to at least 1985, and on an intermittent basis before then, it will be possible to estimate the TSI emission due to identified solar surface features at several solar minima to constrain the role surface magnetic effects have on long-term trends in solar energy output.

Ulrich, R. K.; Parker, D.; Bertello, L.; Boyden, J.

2010-01-01

298

Extraterrestrial Life: Problem Set #1 Due, in class, Thursday January 31st  

E-print Network

of heavy elements (all those elements other than hydrogen and helium) back into space. If the 1011 starsExtraterrestrial Life: Problem Set #1 Due, in class, Thursday January 31st 1) Explain briefly how to search for life? 3) Suppose that a single supernova explosion results in the ejection of 10 Solar masses

Armitage, Phil

299

SETV: opportunity for European initiative in the search for extraterrestrial intelligence  

Microsoft Academic Search

Over the last 50 years, experienced and serious scientists have put forward numerous theories suggesting the possibility that probes sent from extraterrestrial civilizations could theoretically be located within the solar system or near the Earth. A significant body of published theoretical research in this area already exists in books and peer-reviewed journals. What has been missing, however, is the funding

Eamonn Ansbro; Catherine Overhauser

2001-01-01

300

A new empirical approach in the Search for Extraterrestrial Intelligence: Astrobiological nonlocality at the cosmological level  

Microsoft Academic Search

Over a period of several decades a concerted effort has been made to determine whether intelligent life exists outside of our solar system, known as the Search for Extraterrestrial Intelligence or SETI. This has been based primarily upon attempting to intercept possible radio transmissions at different frequencies with arrays of radio telescopes. In addition, astrophysical observations have also been undertaken

Fred H. Thaheld

2006-01-01

301

The impact of gravitational microlensing on searches for extraterrestrial intelligence at optical wavelengths  

Microsoft Academic Search

The search for extraterrestrial intelligence (SETI) at optical wavelengths counts photons from target stars. The rationale is that the number of photons received from a solar-type star in a nanosecond is typically much less than unity and that an excess number of photons may be indicative of a laser pulse from a technological civilization. Extreme magnification gravitational microlensing is a

T. Joseph W. Lazio

2004-01-01

302

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

NASA Astrophysics Data System (ADS)

Accurate and continuous measurements of solar spectral irradiance (SSI) is recognized as being increasingly important to advancing our understanding of the solar influence on Earth's climate. For example, the magnitude of SSI UV variability has significant implications, both directly and indirectly, for the response of the stratosphere and mesosphere, whereas the visible and near infrared SSI variability influences the radiative balance, thermal structure, and dynamics of the lower atmosphere and ocean layers. Recent SSI measurements are providing critical inputs in evaluating and improving present climate models, however they are not yet of sufficient accuracy to stand alone without overlapping records - gaps in the observational record, caused by future mission delays or early failures of existing missions, effectively destroy our ability to link records from different instruments into a continuous, long-term climate quality record. Recent advancements in calibration facilities and techniques make it now possible to improve significantly the accuracy and traceability of future SSI observations and assure quantification of uncertainty as input to increasingly more sophisticated climate models. The goal of the proposed compact SSI monitor is to cover 200-2400 nm with the required SI-traceable accuracy and on-orbit stability to meet the solar input measurement requirements defined in the Earth Science Decadal Survey for establishing benchmark climate records. Building upon our experiences and resources from the Total and Spectral Solar Irradiance Sensor (TSIS) program, the instrument will reduce the cost, size, and characterization and calibration schedule of a solar spectral irradiance monitor with SI-traceable absolute calibration at the 0.2% uncertainty level (k=1) while maintaining 100 ppm relative stability. System level performance characterizations and final end-to-end absolute irradiance calibration will be accomplished with the LASP Spectral Radiometer Facility (SRF), a comprehensive LASP-NIST jointly developed spectral irradiance calibration facility utilizing the SIRCUS tunable laser system tied to an SI-traceable cryogenic radiometer. The instrument utilizes a straightforward low aberration optical design in a compact, folded geometry that overcomes the extremely high tolerance and costly fabrication requirements associated with previous designs while reducing the overall calibration risks. This will potentially mitigate data continuity risks associated with future mission delays by offering an instrument with implementation flexibility for alternative flight opportunities, including ride share and hosted payloads, small satellites and potentially, multi-sensor CubeSat missions, a rapidly emerging technology for low cost orbital science.

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

2013-12-01

303

Modeling Total Solar Irradiance Variations Using Automated Classification Software on Mount Wilson Data  

NASA Astrophysics Data System (ADS)

We present the results of using the AutoClass software, a Bayesian finite mixture model based pattern recognition program developed by Cheeseman and Stutz(1996), on Mount Wilson Solar Observatory (MWO) intensity and magnetogram images to identify spatially resolved areas on the solar surface associated with Total Solar Irradiance (TSI). Using indices based on the resolved solar surface patterns identified by AutoClass from MWO magnetogram and intensity ratio images, and a linear regression fit of those indices to satellite observations of TSI from the Virgo satellite, we are able to model the TSI data from the MWO images with a correlation of better than 0.96 for the period 1996 to 2007. The association of the spatially resolved surface patterns identified by AutoClass with the indices developed from them also allows construction of spatially resolved images of the Sun as it would be "seen" by TSI measuring instruments like Virgo if they were able to capture resolved images. The spatial resolution of these "images" should assist in identifying with greater accuracy the particular solar surface regions associated with TSI variations. Also, since the particular set of MWO data on which this analysis is based is available on a daily basis back to at least 1985, and on an intermittent basis before then, it may be possible to construct an independent estimate of TSI emission at several solar minima.

Ulrich, Roger K.; Parker, D.; Bertello, L.; Boyden, J.

2009-05-01

304

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

NASA Astrophysics Data System (ADS)

The stratosphere is thought to play a central role in the atmospheric response to solar irradiance variability. Recent observations suggest that the spectral solar irradiance (SSI) variability involves significant time-dependent spectral variations, with variable degrees of correlation between wavelengths, and new reconstructions are being developed. In this paper, we propose a simplified modelling framework to characterise the effect of short term SSI variability on stratospheric ozone. We focus on the pure photochemical effect, for it is the best constrained one. The photochemical effect is characterised using an ensemble simulation approach with multiple linear regression analysis. A photochemical column model is used with interactive photolysis for this purpose. Regression models and their coefficients provide a characterisation of the stratospheric ozone response to SSI variability and will allow future inter-comparisons between different SSI reconstructions. As a first step in this study, and to allow comparison with past studies, we take the representation of SSI variability from the Lean (1997) solar minimum and maximum spectra. First, solar maximum-minimum response is analysed for all chemical families and partitioning ratios, and is compared with past studies. The ozone response peaks at 0.18 ppmv (approximately 3%) at 37 km altitude. Second, ensemble simulations are regressed following two linear models. In the simplest case, an adjusted coefficient of determination R2 larger than 0.97 is found throughout the stratosphere using two predictors, namely the previous day's ozone perturbation and the current day's solar irradiance perturbation. A better accuracy (R2 larger than 0.9992) is achieved with an additional predictor, the previous day's solar irradiance perturbation. The regression models also provide simple parameterisations of the ozone perturbation due to SSI variability. Their skills as proxy models are evaluated independently against the photochemistry column model. The bias and RMS error of the best regression model are found smaller than 1% and 15% of the ozone response, respectively. Sensitivities to initial conditions and to magnitude of the SSI variability are also discussed.

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

2012-08-01

305

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 tu- bular photobioreactor under outdoor conditions is pro- posed, 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

F. G. Acién Fernández; F. García Camacho; J. A. Sánchez Pérez; J. M. Fernández Sevilla; E. Molina Grima

1997-01-01

306

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

Microsoft Academic Search

Satellite-derived assessments of surface downwelling solar irradiance are more and more used by engineering companies in solar energy. Performances are judged satisfactory for the time being. Nevertheless, requests for more accuracy are increasing, in particular in the spectral definition and in the decomposition of the global radiation into direct and diffuse radiations. One approach to reach this goal is to

L. Wald; Ph. Blanc

2010-01-01

307

Contribution of UVA irradiance to the erythema and photoaging effects in solar and sunbed exposures.  

PubMed

Even though UVA irradiance had not been considered detrimental to human skin for years, nowadays it is recognized for its role in photoaging and other biological responses. The ratio UVA/UVB is about 17 at a solar zenith angle (SZA) of 20° and it is almost constant up to 60° when it rapidly increases since the UVB wavelengths (280-320nm) are more attenuated than the UVA waveband (320-400nm). For a constant SZA, the ratio increases with the ozone content. The UVA component of the solar erythemal irradiance ranges from 20% at 20° to 30% at 60°, whereas it varies from 50% to 80% in the two different types of measured sunbeds. Moreover, the different spectral distribution of the lamps used for artificial tanning leads frequently to high UVA doses. The biological responses related to skin photoaging (skin sagging and elastosis) could be around fourfold the equivalent solar irradiance at midday in summer midlatitudes and they can be important in unprotected UVA exposures to sunbeds. The UVA dose accumulated during the time required in reaching 1 minimum erythemal dose (MED) increases with the SZA since the exposure durations are longer. Indeed, seasonal differences in the mean UVA dose are observed due to variations in the ozone content that results in longer exposure times without erythema. Although an artificial tanning session is usually shorter than one hour, the UVA dose from sunbeds during the time for 1 MED for skin type II (250Jm(-2)) can be 2-4 times larger than the solar dose, depending on the lamp spectral emission. PMID:25579807

Sola, Yolanda; Lorente, Jerónimo

2015-02-01

308

Technical and economical system comparison of photovoltaic and concentrating solar thermal power systems depending on annual global irradiation  

Microsoft Academic Search

Concentrating solar thermal power and photovoltaics are two major technologies for converting sunlight to electricity. Variations of the annual solar irradiation depending on the site influence their annual efficiency, specific output and electricity generation cost. Detailed technical and economical analyses performed with computer simulations point out differences of solar thermal parabolic trough power plants, non-tracked and two-axis-tracked PV systems. Therefore,

Volker Quaschning

2004-01-01

309

Irradiation effect on the electrical characteristics of an AlGaAs/GaAs based solar cell: Comparison between electron and proton irradiation by numerical simulation  

NASA Astrophysics Data System (ADS)

In this work we use numerical simulation to make a comparison between the effect of electron and proton irradiation on the current voltage (J-V) characteristics of a GaAs based solar cell. This is an extension of a previous work in which we have demonstrated that the use of a gradual gap AlxGa1-xAs window improves the resistivity of the cell to electron irradiation. In this paper we use the gradual gap AlxGa1-x layer as window material on the top of the GaAs cell and we study the effect of its thickness on the output parameters of the cell exposed to 1 MeV electron and proton irradiation. The external cell parameters are: the short circuit current (Jsc), the open circuit voltage (Voc), the fill factor (FF) and the conversion efficiency (?). Our results show that Jsc is more sensitive to electron irradiation while Voc is a little bit more sensitive to proton irradiation. This gives nearly the same effect of the two types of irradiation on the conversion efficiency of the cell. We found also that the increase of the gradual AlxGa1-xAs window thickness from 0.09 to 0.3 ?m improves the resistivity of the solar cell to irradiation.

Laiadi, W.; Meftah, Af.; Sengouga, N.; Meftah, Am.

2013-06-01

310

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

311

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

312

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

313

Charge-coupled device spectrograph for direct solar irradiance and sky radiance measurements.  

PubMed

The characterization of a charged-coupled device (CCD) spectrograph developed at the Laboratory of Atmospheric Physics, Thessaloniki is presented. The absolute sensitivity of the instrument for direct irradiance and sky radiance measurements was determined, respectively, with an uncertainty of 4.4% and 6.6% in the UV-B, and 3% and 6% in the UV-A, visible and near-infrared (NIR) wavelength ranges. The overall uncertainty associated with the direct irradiance and the sky radiance measurements is, respectively, of the order of 5% and 7% in the UV-B, increasing to 10% for low signals [e.g., at solar zenith angles (SZAs) larger than 70 degrees ], and 4% and 6% in the UV-A, visible, and NIR. Direct solar spectral irradiance measurements from an independently calibrated spectroradiometer (Bentham DTM 300) were compared with the corresponding CCD measurements. Their agreement in the wavelength range of 310-500nm is within 0.5% +/- 1.1% (for SZA between 20 degrees and 70 degrees ). Aerosol optical depth (AOD) derived by the two instruments using direct Sun spectra and by a collocated Cimel sunphotometer [Aerosol Robotic network (AERONET)] agree to within 0.02 +/- 0.02 in the range of 315-870 nm. Significant correlation coefficients with a maximum of 0.99 in the range of 340-360 nm and a minimum of 0.90 at 870 nm were found between synchronous AOD measurements with the Bentham and the Cimel instruments. PMID:18382591

Kouremeti, Natalia; Bais, Alkiviadis; Kazadzis, Stelios; Blumthaler, Mario; Schmitt, Rainer

2008-04-01

314

Results of 1 MeV proton irradiation of front and back surfaces of silicon solar cells  

NASA Technical Reports Server (NTRS)

Several silicon solar cells with and without back surface fields (BSF), having thicknesses of 200 microns and 63 microns were irradiated with 1 MeV protons having fluences between 1 times 10 to the 10th power and 1 times 10 to the 12th power p/square cm. The irradiation was performed using both normal and isotropic incidence on the front as well as back surfaces of the solar cells. The results of the back surface irradiations are analyzed using a model in which irradiation induced defects across the high-low (BSF) junction are considered. It is concluded that degradation of the high-low junction is responsible for the severe performance loss in thinner cells when irradiated from the rear.

Anspaugh, B. E.; Kachare, R.; Weizer, V. G.

1987-01-01

315

Niel Dose Dependence for Solar Cells Irradiated with Electrons and Protons  

NASA Astrophysics Data System (ADS)

The investigation of solar cells degradation and the prediction of its end-of-life performance is of primary importance in the preparation of a space mission. In the present work, we investigate the reduction of solar-cells' maximum power resulting from irradiations with electrons and protons. Both GaAs single junction and GalnP/GaAs/Ge triple junction solar cells were studied. The results obtained indicate how i) the dominant radiation damaging mechanism is due to atomic displacements, ii) the relative maximum power degradation is almost independent of the type of incoming particle, i.e., iii) to a first approximation, the fitted semi-empirical function expressing the decrease of maximum power depends only on the absorbed NIEL dose, and iv) the actual displacement threshold energy value (Ed = 21 eV) accounts for annealing treatments, mostly due to self-annealing induced effects. Thus, for a given type of solar cell, a unique maximum power degradation curve can be determined as a function of the absorbed NIEL dose. The latter expression allows one to predict the performance of those solar cells in space radiation environment.

Baur, C.; Gervasi, M.; Nieminen, P.; Pensotti, S.; Rancoita, P. G.; Tacconi, M.

2014-06-01

316

NIEL Dose Dependence for Solar Cells Irradiated with Electrons and Protons  

E-print Network

The investigation of solar cells degradation and the prediction of its end-of-life performance is of primary importance in the preparation of a space mission. In the present work, we investigate the reduction of solar-cells' maximum power resulting from irradiations with electrons and protons. Both GaAs single junction and GaInP/GaAs/Ge triple junction solar cells were studied. The results obtained indicate how i) the dominant radiation damaging mechanism is due to atomic displacements, ii) the relative maximum power degradation is almost independent of the type of incoming particle, i.e., iii) to a first approximation, the fitted semi-empirical function expressing the decrease of maximum power depends only on the absorbed NIEL dose, and iv) the actual displacement threshold energy value (Ed=21 eV) accounts for annealing treatments, mostly due to self-annealing induced effects. Thus, for a given type of solar cell, a unique maximum power degradation curve can be determined as a function of the absorbed NIEL dose. The latter expression allows one to predict the performance of those solar cells in space radiation environment.

C. Baur; M. Gervasi; P. Nieminen; S. Pensotti; P. G. Rancoita; M. Tacconi

2014-02-10

317

Modeling Total Solar Irradiance Variations Using Automated Classification Software On Mount Wilson Data  

E-print Network

We present results using the AutoClass analysis application available at NASA/Ames Intelligent Systems Div. (2002) which is a Bayesian, finite mixture model classification system developed by Cheeseman and Stutz (1996). We apply this system to Mount Wilson Solar Observatory (MWO) intensity and magnetogram images and classify individual pixels on the solar surface to calculate daily indices that are then correlated with total solar irradiance (TSI) to yield a set of regression coefficients. This approach allows us to model the TSI with a correlation of better than 0.96 for the period 1996 to 2007. These regression coefficients applied to classified pixels on the observed solar surface allow the construction of images of the Sun as it would be seen by TSI measuring instruments like the Solar Bolometric Imager recently flown by Foukal et al., (2004). As a consequence of the very high correlation we achieve in reproducing the TSI record, our approach holds out the possibility of creating an on-going, accurate, in...

Ulrich, R K; Bertello, L; Boyden, J

2009-01-01

318

Analyzing and simulating the variability of solar irradiance and solar PV powerplants  

E-print Network

due to the sun’s movement through the sky: maximum power ison the sun and solar energy. What a source of power! I hopeand power output timeseries are seasonal and diurnal cycles relating to changes in the Earth-Sun

Lave, Matthew S.

2012-01-01

319

Analyzing and simulating the variability of solar irradiance and solar PV powerplants  

E-print Network

grid as SRRL and NWTC will dampen fluctuations in solar powersolar photovoltaic (PV) power due to cloud-caused fluctuations is a concern for electric gridsolar PV powerplants as unanticipated changes in PV plant power output can strain the electric grid.

Lave, Matthew S.

2012-01-01

320

On the Importance of the Flare's Late Phase for the Solar Extreme Ultraviolet Irradiance  

NASA Technical Reports Server (NTRS)

The new solar extreme ultraviolet (EUV) irradiance observations from NASA Solar Dynamics Observatory (SDO) have revealed a new class of solar flares that are referred to as late phase flares. These flares are characterized by the hot 2-5 MK coronal emissions (e.g., Fe XVI 33.5 nm) showing large secondary peaks that appear many minutes to hours after an eruptive flare event. In contrast, the cool 0.7-1.5 MK coronal emissions (e.g., Fe IX 17.1 nm) usually dim immediately after the flare onset and do not recover until after the delayed second peak of the hot coronal emissions. We refer to this period of 1-5 hours after the fl amrea sin phase as the late phase, and this late phase is uniquely different than long duration flares associated with 2-ribbon flares or large filament eruptions. Our analysis of the late phase flare events indicates that the late phase involves hot coronal loops near the flaring region, not directly related to the original flaring loop system but rather with the higher post-eruption fields. Another finding is that space weather applications concerning Earth s ionosphere and thermosphere need to consider these late phase flares because they can enhance the total EUV irradiance flare variation by a factor of 2 when the late phase contribution is included.

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

2011-01-01

321

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.

322

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.

323

Evaluation of Solar Irradiance Models with a Special Referenceto Globally-Parameterized and Land Cover-Sensitive Solar123  

NASA Astrophysics Data System (ADS)

Numerical models are often the only means available to generate solar irradiance (SR) information, for historical or future SR specifications as well as due to inadequacies of contemporary SR measurements. This paper evaluates five such models that have been proposed as generic and applied as such. Special emphasis is given to Solar123, an integrative model rooted in Lambert's Cosine Law and Bouguer's Law with globally-parameterized atmospheric property functions and with input limited to precipitation, air temperature, geographic location, topography and rudimentary land cover information. The selected SR models in general perform well in reproducing the SR data for the USA, with a root mean square error-to-data mean ratio (RMSE/SRmean ratio) of 9.8-11.4%. A possible exception is the Bristow-Campbell logic as implemented by the Vegetation/Ecosystem Modeling and Analysis Project. Beyond the USA, Solar123 yields an RMSE/SRmean ratio of 8-17% by region (196 stations in total), generally outperforming the other SR models. Compared to time-sequential monthly SR data, projections by Solar123 have an RMSE/SRmean ratio of 8.6-14.1% for six weather stations representative of major climate regimes in Canada, or an RMSE/SRmean ratio of 13-24% for three forest sites in the USA, Germany and Japan. Solar123 projections also compare favorably against the output from the General Circulation Models in terms of ratio change in SR with the doubling of the atmospheric carbon-dioxide concentration: the two fall within +/-10% of each other for 85% of a total 264 cases, and within +/-20% for all but 3 of the cases. The above statistics suggest that Solar123 represents an improvement over other SR models not only in configuration but also in projection accuracy, and that Solar123 is useful for projecting spatial variation in SR across weather stations around the world and over different land covers, and for projecting temporal variation in SR under the present climate regimes and likely for regimes changed beyond the present fluctuation range. The work further calls into question the common practice of applying SR data irrespective of local land cover.

Yin, X.

324

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

325

Short circuit current changes in electron irradiated GaAlAs/GaAs solar cells  

NASA Technical Reports Server (NTRS)

Heteroface p-GaAlAs/p-GaAs/n-GaAs solar cells with junction depths of 0.8, 1.5, and 4 microns were irradiated with 1 MeV electrons. The short-circuit current for the 4 micron junction depth cells is significantly reduced by the electron irradiation. Reduction of the junction depth to 1.5 microns improves the electron radiation resistance of the cells while further reduction of the junction depth to 0.8 microns improves the stability of the cells even more. Primary degradation is in the blue region of the spectrum. Considerable recovery of lost response is obtained by annealing the cells at 200 C. Computer modeling shows that the degradation is caused primarily by a reduction in the minority carrier diffusion length in the p-GaAs.

Walker, G. H.; Conway, E. J.

1978-01-01

326

Photoluminescence analysis of electron irradiation-induced defects in GaAs/Ge space solar cells  

NASA Astrophysics Data System (ADS)

Photoluminescence measurements were carried out to investigate the degradation for GaAs/Ge space solar cells which were irradiated with 1.0, 1.8, and 11.5 MeV electrons with fluences up to 3 × 1015 cm-2. The product of the defect introduction rate and the minority carrier capture cross section by electron irradiation-induced defects was determined with photoluminescence radiative efficiency related to the non-radiative recombination lifetime. Then the cross section was acquired according to the relation between the defect introduction rate and the non-ionizing energy loss. Furthermore, the non-radiative recombination could be identified among all the detected defects by comparing the cross section of the minority carrier capture.

Ming, Lu; Rong, Wang; Kui, Yang; Tiancheng, Yi

2013-10-01

327

keV ion irradiation assisted prebiotic synthesis of oligopeptide in the solar system  

NASA Astrophysics Data System (ADS)

In this paper, keV ion assisted peptide formation from amino acid monomers is studied. To investigate the possible role of low energy ion irradiation in prebiotic synthesis of oligopeptides, we applied keV Ar + and N + ion beams to solid state phenylalanine. After ion irradiation, it was found that phenylalanine dipeptide was formed and the optimal pH value for peptide formation was 8-9. A radical mechanism was also deduced for our observations. In view of the ubiquitous existence of keV ions in early space and on the early Earth, we suggest that low energy charged particles might have played a role in chemical evolution in the solar system.

Wang, W.; Yuan, H.; Wang, X.; Yu, Z.

328

Dependence of lunar surface charging on solar wind plasma conditions and solar irradiation  

NASA Astrophysics Data System (ADS)

The surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the photoemission of electrons Jp, and the collection of plasma electrons Je, and ions Ji. These currents are dependent on the following six parameters: plasma concentration n0, electron temperature Te, ion temperature Ti, bulk flow velocity V, photoemission current at normal incidence JP0, and photoelectron temperature Tp. Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, Te is the most important parameter, especially near the terminator, while JP0 and Tp dominate over most of the dayside. In contrast, V and Ti are found to be the least effective parameters. Typically, lunar surface charging in the solar wind can be reduced to a two-current problem: on the dayside in sunlight, Jp+Je=0, since ? Jp? ? ? Je? ? ? Ji? , while near the terminator in shadow, Je+Ji=0. However, situations can arise that result in a truly three-current problem with some important consequences; e.g., very cold Te and/or very fast V can result in ? Jp? ? ? Je? ? ? Ji? on the dayside. The influence of surface charging pervades the environments of the Moon and other airless bodies, and the investigation presented here provides insights into the physical processes involved, as well as being useful for interpreting and understanding more complicated simulations

Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.; Burchill, J. K.; Collier, M. R.; Zimmerman, M. I.; Vondrak, R. R.; Delory, G. T.; Pfaff, R. F.

2014-01-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

330

Solar Irradiance Changes and Photobiological Effects at Earth's Surface Following Astrophysical Ionizing Radiation Events.  

PubMed

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance but that relative estimates for increase in exposure to DNA-damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events. Key Words: UV radiation-Supernovae-Extinctions-Radiative transfer. Astrobiology 15, 207-220. PMID:25692406

Thomas, Brian C; Neale, Patrick J; Snyder, Brock R

2015-03-01

331

Satellite observations of fog over Indo-Gangetic Plains and its influence on solar irradiance  

NASA Astrophysics Data System (ADS)

Every year, the Northern region of India, especially the Indo-Gangetic Plains (IGPs) region ex-perience severe fog conditions during winter season due to typical meteorological, environmental and prevailing terrain conditions. The IGP region is highly influenced by western disturbances during winter season, which provide ideal conditions for accumulation of pollutants within the boundary layer and often results in fog formation. The formation of fog over IGPs is believed to create numerous health hazards, economic loss and cross-country transportation of aerosols. The fog is also expected to have impact on agriculture, general economy, global and regional climate. It has attracted the global scientific community attention to address the uncertainties pertaining to its formation and physico-chemical properties. The increase in aerosol concen-tration in the lower atmosphere due to biomass-burning events and anthropogenic activities provides more fog formation with water vapor present in atmosphere over IGP region. In the present study, we made an attempt to study the fog conditions that occurred over North In-dian region and long range transport of aerosols from fog region towards southern region during November, 2008 using multi-satellite data sets and ground based observations on aerosol prop-erties and solar irradiance at urban region of Hyderabad, India. False Color Composites (FCC) of IRS-P6 AWiFS, IRS-P4 OCM and Terra/Aqua MODIS images showed an intense fog/aerosol layer over IGP region on 07th -09th November, 2008. The Terra/Aqua MODIS AOD500 and OMI-AI observations showed high values over IGP region due to fog layer and long range trans-port of aerosols from IGP to Southern Indian region. CALIPSO LIDAR observation showed thick layer of fog/aerosols up to above northern/central Indian region with thickness ranging from 1.5 to 3 Kms. NCEP temperature anomaly variation at 700 hPa showed higher values over IGP region attributed upper atmospheric heating due to scattering and absorption of solar irra-diance. Nighttime ground based micro-pulsed lidar observations at Hyderabad showed elevated layer at a height of 5km on 07 November 2008 confirming the long-range transport of aerosols from fog region (IGP) over urban region of Hyderabad, India. Ground-based sun photometer measurements showed considerable increase in AOD500 ( 30%), angstrom parameter ? ( 10%) and decrease in total solar irradiance ( 7%) over Hyderabad, India on 07 November during the fog period compared to normal day corresponding to 04 November 2008. Keywords: Fog, IGP, AOD, LIDAR and solar irradiance

Kharol, Shailesh Kumar; Rani Sharma, Anu; Kvs, Badarinath; Roy, P. S.

332

Extraterrestrial intelligence - An observational approach  

NASA Technical Reports Server (NTRS)

The article surveys present and proposed search techniques for extraterrestrial intelligence in terms of technological requirements. It is proposed that computer systems used along with existing antennas may be utilized to search for radio signals over a broad frequency range. A general search within the electromagnetic spectrum would explore frequency, received power flux, spatial locations, and modulation. Previous SETI projects (beginning in 1960) are briefly described. An observation project is proposed in which the earth's rotational motion would scan the antenna beam along one declination circle in 24 hours. The 15 degree beam width would yield a mapping of 75% of the sky in an 8-day period if the beam were shifted 15 degrees per day. With the proposed instrument parameters, a sensitivity of about 10 to the -21 watt/sq m is achieved at a 0 degree declination and 1.5 GHz. In a second phase, a 26 m antenna would yield an HPBW of 0.8 degrees at 1 GHz and 0.03 degrees at 25 GHz. It is noted that the described technology would provide secondary benefits for radio astronomy, radio communications, and other fields.

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

1978-01-01

333

On the Connection between Solar Spectral Irradiance and Planetary Wave Drag  

NASA Astrophysics Data System (ADS)

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 in PWD may have potentially far-reaching consequences for the global circulation, ranging from changes in the zonal-mean flow to changes in the Brewer-Dobson circulation, it is important to understand the connection between SSI and PWD. In this study we employ a mechanistic model that couples radiation, ozone and dynamics to derive an analytical expression that shows the explicit connection between SSI and PWD. The sensitivity of the stratospheric circulation, particularly stratospheric sudden warmings, to changes in SSI associated with the SC is explored.

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

2007-12-01

334

Do spaceborne aerosol observations limit the accuracy of modeled surface solar irradiance?  

NASA Astrophysics Data System (ADS)

play a primary role in the global climate system and the solar radiation budget at the Earth surface. Here we analyze the role of spaceborne aerosol observations and their uncertainties in the expected accuracy of the modeled cloudless surface shortwave downward radiation using a state-of-the-art numerical weather prediction model over the continental U.S. We compare five different modeling approaches for the aerosol optical effects with differing sophistication. Overall, we show that, counterintuitively, the direct and diffuse irradiances predicted by solar radiation models that use empirically adjusted fixed aerosol extinction may be more accurate than more sophisticated radiative transfer models that require inputs of aerosols. We conclude that, compared to ground observations, the mean absolute error in satellite-retrieved aerosol optical depth over the U.S., and possibly elsewhere, should be reduced to less than 0.025 aerosol optical depth unit to assure improvement over the predictions of a simpler, aerosol-insensitive radiation model.

Ruiz-Arias, José A.; Gueymard, Christian A.; Santos-Alamillos, Francisco J.; Pozo-Vázquez, David

2015-01-01

335

Irradiated solar cells fabricated from gallium-doped/boron-doped FZ and CZ silicon  

SciTech Connect

The purpose of this study is to compare the tolerance to various fluence levels of 1 MeV electrons of solar cells fabricated from: gallium-doped multipass FZ silicon, boron-doped multipass FZ silicon, gallium doped CZ silicon and boron doped CZ silicon. The FZ materials used for the study were of ultra high purity with low levels of oxygen and carbon. Bulk analysis of gallium doped cold crucible (C/sup 3/Z) silicon is included and compared with gallium doped FZ silicon. Bulk analysis of selected wafers in the various crystals was performed by low temperature FTIR and surface photovoltage. Measurement of AMO electrical characteristics and spectral response of solar cells fabricated from these silicon materials before and after 1 MeV electron irradiation are used to compare radiation tolerance of the materials.

Minahan, J.A.; Dionne, N.N.D.; Taylor, W.E.; Trumble, T.M.

1982-09-01

336

Displacement damage-induced electrical and structural effects in gallium arsenide solar cells following ion irradiation  

NASA Astrophysics Data System (ADS)

For nearly two decades, deviations between experimental data and the nonionizing energy loss (NIEL) have been observed for GaAs devices. In particular, previous data has suggested that electrical parameters associated with GaAs solar cells can follow different energy dependences with NIEL but only at the higher proton energies. In this paper, displacement damage-induced electrical and structural effects in GaAs solar cells were monitored before and after irradiation with various ions. The radiation-induced defects responsible for causing electrical changes were characterized using illuminated current-voltage, deep level transient spectroscopy (DLTS), and electron beam induced current (EBIC) while the structural changes were monitored using transmission electron microscopy (TEM). The EBIC images showed the existence of radiation-induced active recombination volumes or defect clusters after irradiation with high energy protons (E ? 10 MeV) and 22 MeV silicon ions, which were not produced by lower energy protons. The TEM images revealed strain related defects that correspond to the same irradiation conditions for which the defect clusters were observed, and therefore, the defects in the TEM images are associated with those observed in the EBIC images. These defects were not observed prior to irradiation so the lattice strain in the material is definitely associated with irradiation-induced lattice defects. HRTEM imaging has shown that the disordered regions are not amorphous but probably most likely a cluster of vacancies and a surrounding region rich in interstitials, which is produced when a large number of neighboring atoms are displaced in collision cascades known as the displacement spike. The formation of the U-band defect as determined by DLTS seems to evolve under the same irradiation conditions as the defects in the images. This very broad U-band peak is consistent with what would be expected from defect clusters. From analyses of the recoil spectra, high energy recoils appear to be responsible for the formation of these disordered regions and these regions are independent of the total displacement damage energy deposited. This study has shown that NIEL scaling is only violated for incident ion energies when the defect clusters are observed.

Warner, Jeffrey Hamilton

337

Solar wind and cosmic ray irradiation of grains and ices - application to erosion and synthesis of organic compounds in the solar system  

NASA Technical Reports Server (NTRS)

Solar wind and cosmic and cosmic ray irradiation of grains induces physical and chemical effects including their erosion and the synthesis of molecular compounds within the implanted layers. The experiments performed with H2O ice implanted by keV ions are presented. The ion implantation is intended to simulate the irradiation of comets, ring grains, and satellites of outer planets, either by the primitive solar particles or by contemporary solar wind (SW) or solar cosmic rays (SCR) fluxes. The detection of molecules was obtained through in-situ infrared spectroscopy. A model is proposed for the formation of organic matter within icy solar system bodies which is in agreement with experimental results of erosion rates. The organic molecules, frozen-in within the icy mantles of the grains present in the protosolar nebula, would originate from their primitive irradiation. Such an irradiation would have taken place during an early stage of the proto-sun, when both the SW and SCR particles were more intense by orders of magnitude.

Rocard, F.; Benit, J.; Meunier, J. P.; Bibring, R.; Vassent, B.

1984-01-01

338

Characterization of solar cells for space applications. Volume 12: Electrical characteristics of Solarex BSF, 2-ohm-cm, 50-micron solar cells (1978 pilot line) as a function of intensity, temperature, and irradiation  

NASA Technical Reports Server (NTRS)

Electrical characteristics of Solarex back-surface-field, 2-ohm-cm, 50-micron N/P silicon solar cells are presented in graphical and tabular format as a function of solar illumination intensity, temperature, and irradiation.

Anspaugh, B. E.; Beckert, D. M.; Downing, R. G.; Miyahira, T. F.; Weiss, R. S.

1980-01-01

339

Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22  

NASA Technical Reports Server (NTRS)

This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

1996-01-01

340

Detecting extraterrestrial life with the Colossus telescope using photosynthetic biosignatures  

NASA Astrophysics Data System (ADS)

We propose to search for life on Earth-like planets in habitable zones using photosynthesis biosignatures. Many life forms on Earth process the solar light and utilize it to support their own activity and to provide a valuable energy source for other life forms. We expect therefore that photosynthesis is very likely to arise on another planet and can produce conspicuous biosignatures. We have recently identified biological polarization effects, e.g., selective light absorption or scattering by photosynthetic molecules which can be used for remote detection of extraterrestrial life. Here we present synthetic spectra and polarization of Earth-like planets with photosynthetic life and evaluate the sensitivity of the Colossus telescope for their remote detection in the solar neighborhood.

Berdyugina, S.; Kuhn, J.; Harrington, D.; Moretto, G.; Langlois, M.; Halliday, D.; Harlingten, C.

2014-03-01

341

SETI - The search for extraterrestrial intelligence - Plans and rationale  

NASA Technical Reports Server (NTRS)

The methodology and instrumentation of a 10 yr search for extraterrestrial intelligence (SETI) program by NASA, comprising 5 yr for instrumentation development and 5 yr for observations, is described. A full sky survey in two polarizations between 1.2 and 10 GHz with resolution binwidths down to 32 Hz, and a two polarization can between 1.2-3 GHz with resolution binwidths down to 1 Hz of 700 nearby solar type stars within 20 light years of earth will extend the sensitivity of previous surveys by 300 times and cover 20,000 times more frequency space. EM signals are perceived as the only means for detecting life outside the solar system, and the SETI effort is driven by the empirical experience that once a physical process has been observed to occur, its occurrence elsewhere is assured. Further discussion is given of the history of searches for life in the Universe, the SETI search strategy, instrumentation, and signal identification.

Wolfe, J. H.; Billingham, J.; Edelson, R. E.; Crow, R. B.; Gulkis, S.; Olsen, E. T.; Oliver, B. M.; Peterson, A. M.

1981-01-01

342

A search strategy for SETI - The search for extraterrestrial intelligence  

NASA Technical Reports Server (NTRS)

A search strategy is proposed for the detection of signals of extraterrestrial intelligent origin. It constitutes an exploration of a well defined volume of search space in the microwave region of the spectrum and envisages the use of a combination of sky survey and targeted star approaches. It is predicated on the use of existing antennas equipped with sophisticated multichannel spectrum analyzers and signal processing systems operating in the digital mode. The entire sky would be surveyed between 1 and 10 GHz with resolution bin widths down to 32 Hz. More than 700 nearby solar type stars and other selected interesting directions would be searched between 1 GHz and 3 GHz with bin widths down to 1 Hz. Particular emphasis would be placed on those solar type stars that are within 20 light years of earth.

Billingham, J.; Wolfe, J.; Edelson, R.; Gulkis, S.; Olsen, E.; Oliver, B.; Tarter, J.; Seeger, C.

1980-01-01

343

Near real-time reconstruction of the solar spectral irradiance in the UV-EUV  

NASA Astrophysics Data System (ADS)

The solar radiative output in the UV and Extreme-UV (EUV) is a crucial quantity for space weather applications that require a specification of the thermosphere/ionosphere system, but also for the forcing of climate. The continuous monitoring of the UV/EUV spectrum is a major instrumental challenge, so that alternatives must be found to ensure the continuity of the observations. This is a timely issue as the SORCE satellite is not expected to last for much longer. Numerous studies have shown that the salient features of the solar spectral variability can be reconstructed from the evolution of the photospheric magnetic field. We have developed an artificial neural network model to compute the UV/EUV spectrum in near-real time, using magnetograms from SDO/HMI. The magnetic structures are identified and classified according to the area of the solar disk covered. We constrain the model by comparing its output with observations made by instruments onboard of SORCE satellite. The model allows us to nowcast and forecast the total and spectral solar irradiance up to one week days in advance. In addition, it gives deeper insight into the contributions to the spectral variability. The model output is available at http://www.lpc2e.cnrs-orleans.fr/~soteria.

Vuiets, Anatoliy; Vieira, Luis Eduardo; Dudok de Wit, Thierry; Kretzschmar, Matthieu

2013-04-01

344

A Investigation of the Relationship Between Beam and Global Irradiation with the Development of Numerical Solar Radiation Models.  

NASA Astrophysics Data System (ADS)

A number of improved numerical models have been developed to predict the beam radiation from global radiation data. The analysis was based on five years of hourly radiation data collected at the Solar Total Energy Project in Shenandoah, Georgia. Previously developed empirical correlations relate hourly values of the beam transmittance, tau _{rm b}--beam normal radiation over the extraterrestrial normal radiation, to clearness index, k_{rm t} --global radiation over the extraterrestrial global radiation. The relationship of tau_{rm b}-k_{rm t} , though, is not deterministic. Some the observed variation was explained by a seasonal dependence. Improved performance was achieved by introducing a third variable, either the atmospheric air-mass (m), or the temporal variation coefficient, eta, a new dimensionless parameter used to describe the sky condition without using any meteorological information. Seasonal effects on solar radiation caused by cloudiness and air quality were found to be significant and two methods were developed to account for this phenomenon. The air-mass dependence of solar radiation was examined through a study of the relationships between (tau _{rm b}-m) and (k _{rm t}-m). A simple clear sky beam transmittance model was developed for the region, although it was shown that clearest skies are not necessarily site specific. Two improved beam radiation models were developed, relating three variables at a time--namely (k_ {rm t},m,tau_ {rm b}) and (k_{ rm t},eta, tau_{rm b}). These correlations have significantly increased the predictive powers of the beam radiation model, without compensating for additional input information. These models can predict different values of beam radiation for a given day and over the year, for the same value of global radiation which is what is observed. Several surface fitting techniques were used to generate the response surface among which are, a best RMS triangulation method, an inversely weighted fit method, and a fifth-degree polynomial fit. The work satisfies a major deficiency in solar radiation modeling by providing the most accurate up-to -date models for the southeast United States. The proposed models were validated with data from the National Observatory of Athens, Greece. The good performance of the models is reassuring of their wide applicability.

Balaras, Constantinos Agelou

345

Estimating Total Solar Irradiance Composites (ACRIM and PMOD): From the Medieval Warm Period to the 21st century  

NASA Astrophysics Data System (ADS)

The Total Solar Irradiance is one of the fundamental energy sources of the Earth’s climate and therefore its variations can contribute to natural climate changes. This variability is characterized by, among others, decadal and secular oscillations motivating attempts to estimate future solar activity. The estimation of solar activity for the next hundred years is one of the current problems in solar physics because the possible occurrence of a future grand solar minimum will certainly have an impact on Earth’s climate. Here we attempted an estimation of the Total Solar Irradiance using the PMOD and ACRIM composites, from the Medieval Warm Period to the 21st century. We found that the solar activity grand minima periodicity is of 120 years; this periodicity could possibly be one of the principal periodicities of the magnetic solar activity. The negative 120-years phase coincides with the grand minima of the 11-years periodicity. To decide when the solar activity is “high” or “low”, we calculate the power of the TSI as a direct indicator of energy released by the solar dynamo and the level of activity for each solar cycle. We use the mean power value of the PMOD and ACRIM composites (1979 - 2013) to calculate the anomalies for each cycle. The calculated power anomalies show that low solar secular activity occurs when there are negative anomalies and high solar secular activity appears with positive anomalies. It is possible that the zero in the anomalies, represents the normal state of the dynamo. The “Prolonged Sunspot Minimum” discovered by Maunder, represents a phase of solar history and corresponds to a special state of the dynamo when it is working well below its average power.

Velasco Herrera, Victor Manuel; Mendoza, Blanca; Velasco-Herrera, Graciela

346

Estimates and Measurements of Photosynthetically Active Radiation and Global Solar Irradiance in Rondonia  

SciTech Connect

Measurements of photosynthetically active radiation (PAR) and global solar irradiance (R{sub s}) were made at a LBA (The Large Scale Biosphere-Atmosphere Experiment in Amazonia) experimental site, at Fazenda Nossa Senhora (10 deg. 45' S; 62 deg. 21' W), in Rondonia, in the years of 2004 and 2005, with the objective of estimating the seasonal variation of the ratio between the photosynthetically active radiation and the global solar irradiance. The relationship between PAR and R{sub s} were made by using linear regressions equations with data from year 2004 and tested with data from the year 2005. The seasonal variation of the ratio PAR/R{sub s} ranged from 0.43 (September) to 0.48 (January). The linear regression equations between PAR and R{sub s} obtained were: a) On an hourly basis: PAR 0.747+0.478*R{sub s},(R{sup 2} = 0.99; wet season) and PAR = -4.578+0.452*R{sub s}(R{sup 2} 0.99; dry season); b) On a daily basis: PAR = 4.956+0.466*R{sub s}(R{sup 2} = 0.99; wet season) and PAR = -6.762+0.457*R{sub s}(R{sup 2} = 0.96; dry season)

Aguiar, Leonardo J. G.; Costa, Jose M. N. da; Fischer, Graciela R. [Department of Agricultural Engineering, Federal University of Vicosa, CEP 36570000, Vicosa-MG (Brazil); Aguiar, Renata G. [Department of Ambiental Engineering, Federal University of Rondonia, CEP 78960000, Ji-Parana-RO (Brazil)

2009-03-11

347

Forecasting sub-hourly solar irradiance for prediction of photovoltaic output  

NASA Astrophysics Data System (ADS)

Short-term prediction of photovoltaic power output through forecast of global solar irradiance in the subhourly time frame is explored. The decomposition of the global solar irradiance into a deterministic clear sky component and a stochastic cloud cover component is achieved through a parameterization process. The cloud cover time series is modeled by a Box-Jenkins-type ARIMA model and forecasts issued hourly for specified interval periods throughout the hour. Results show that when compared to actual data measured at several locations in the southeastern United States, the forecasts are quite accurate and the model is site-independent. Forecasts are found to be inaccurate only when there are sudden changes in the cloud cover moving across the sun. In other words, the randomness involved in sudden extreme changes in the sun's intensity during a single interval will not be picked up by the forecast model and is generally considered impossible to predict by any forecast model. One of the many application of the forecast methodology is to dispatch photovoltaic power output in the optimal power dispatch scheme of electric utilities.

Chowdhury, Badrul H.; Rahman, Saifur

348

Assessment of underwater irradiance and absorption of solar radiation at water column from satellite data  

NASA Astrophysics Data System (ADS)

The volume absorption of solar radiation in water body determines important processes in the upper ocean such as primary bioproduction and heat balance. Assessment of penetration of solar radiation into water body can be performed with satellite data and the previous attempts in this direction were promising. This paper presents a package of the algorithms to compute the components of balance of photosynthetically available radiation (PAR) at sea level (incident, reflected from the rough sea surface, and water-leaving PAR) and to calculate the volume absorption of PAR in the upper layer from satellite ocean color data. Data measured by the SeaWiFS ocean color sensor and the ancillary data needed (such as ozone amount and wind speed) are used. Computations of the underwater irradiance are performed for the 0-25 m upper layer. The errors are estimated by direct comparison between the values of underwater irradiance and volume absorption derived by the algorithms developed and by the exact method. Monthly means of the components of PAR balance as well as the potential daily heating have been estimated in different regions.

Kopelevich, Oleg V.; Sheberstov, Sergey V.; Burenkov, Vladimir I.; Vazyulya, Svetlana V.; Likhacheva, Maria V.

2007-04-01

349

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

350

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

351

Infrared Spetroscopy 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, William T.; Yesaltis, M.; Rossman, G.

2012-10-01

352

Interannual variability of solar irradiance over the Amazon Basin including the 1982-83 El Nino Year  

NASA Technical Reports Server (NTRS)

Surface solar irradiance was derived over the extended Amazon Basin using AVHRR observations from polar-orbiting satellites during four July months (1983-1986). Observations from the geostationary satellite GOES for July 1983 were also used to assess diurnal effects. Both satellite datasets are part of the Satellite Cloud Climatology Project (ISCCP) B3 product. It was demonstrated that it is now possible to derive long-term surface solar irradiance, which can be useful in climate studies, and that the accuracy of the derived fields is sufficient to detect interannual differences that can exceed at times 70 W/sq m.

Pinker, Rachel T.; Laszlo, I.

1992-01-01

353

Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells  

SciTech Connect

The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

2014-04-24

354

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

355

Midwestern streamflow, precipitation, and atmospheric vorticity influenced by Pacific sea-surface temperatures and total solar-irradiance variations  

USGS Publications Warehouse

A solar effect on streamflow in the Midwestern United States is described and supported in a six-step physical connection between total solar irradiance (TSI), tropical sea-surface temperatures (SSTs), extratropical SSTs, jet-stream vorticity, surface-layer vorticity, precipitation, and streamflow. Variations in the correlations among the individual steps indicate that the solar/hydroclimatic mechanism is complex and has a time element (lag) that may not be constant. Correct phasing, supported by consistent spectral peaks between 0.092 and 0.096 cycles per year in all data sets within the mechanism is strong evidence for its existence. A significant correlation exists between total solar irradiance and the 3-year moving average of annual streamflow for Iowa (R = 0.67) and for the Mississippi River at St Louis, Missouri (R = 0.60), during the period 1950-2000. Published in 2005 by John Wiley & Sons, Ltd.

Perry, C.A.

2006-01-01

356

Cross Sections Needed for the Interpretation of Long-Lived and Short-Lived Cosmogenic Nuclide Production in Extraterrestrial Materials  

NASA Astrophysics Data System (ADS)

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in lunar rocks, accurate and precise cross section values for the production of these radionuclides from all relevant elements are needed. About 98% of SCR and ~87% of galactic cosmic rays (GCR) falling on extraterrestrial materials are protons. Cross section measurements were made using three proton accelerators to cover the energy range ~20 - 500 MeV. Thin target techniques used in the irradiations minimized the number of protons scattered out of the stack and the neutron production within the stack. After irradiation, the short-lived radionuclides e.g. 22Na, 7Be, 24Na, 54Mn, and 56Co were determined using gamma-ray spectroscopy. 14C, 10Be, and 26Al were determined using Accelerator Mass Spectrometry. Our main objective is to measure the production cross sections of long-lived radionuclides. We have reported new cross section values for making 10Be from O and 14C from O, Mg, Al, Si, Fe, and Ni [1,2]. Using these new results, better estimates for the solar proton flux over several time periods in the past were determined [3]. However, no single value for the SCR flux could explain the measured data from different time periods. Further cross section measurements are being made to verify that the values used in these estimates were accurate. Irradiations designed to give good cross section measurements for long-lived radionuclides also give good cross section measurements for short-lived radionuclides. Results will be presented for proton production cross sections of 22Na from Mg, Al and Si, and 54Mn and 56Co from Fe and Ni; some values at low energies were reported previously [4]. These cross sections and other reported measurements [5, 6] will be used to improve the estimates of the recent SCR fluxes from the depth profiles for 22Na measured in lunar rocks [7, 8], and to better understand the SCR cosmogenic radionuclide production observed in Salem [9] and other other extraterrestrial materials. References: [1] Sisterson J. M. et al. (1992) LPS XXIII, 1305. [2] Sisterson J. M. et al. (1995) LPS XXVI, 1309. [3] Rao M. N. et al. (1994) GCA, 58, 4231. [4] Beverding A. M. et al. (1994) USGS Circular 1107, 29. [5] Michel R. and Stueck R. (1984) Proc. LPSC 14th, in JGR, 89, B673. [6] Bodemann R. et al. (1993) Nucl. Instr. Meth. Phys. Res., B82, 9. [7] Reedy R. C. (1977) Proc. LSC 8th, 825. [8] Fruchter J. S. et al. (1982) LPS XIII, 243. [9] Evans J. C. et al. (1987) LPS XVIII, 271.

Sisterson, J. M.; Beverding, A.; Kim, K. J.; Englert, P. A. J.; Jull, A. J. T.; Donahue, D. J.; Cloudt, S.; Castaneda, C.; Vincent, J.; Caffee, M. W.; Osazuwa, C. O.; Reedy, R. C.

1995-09-01

357

Enhanced efficiency of the dye-sensitized solar cells by excimer laser irradiated carbon nanotube network counter electrode  

SciTech Connect

The carbon nanotube network decorated with Pt nanoparticles (PtCNT) irradiated by excimer laser as counter electrode (CE) of dye-sensitized solar cells (DSSCs) has been systematically demonstrated. The conversion efficiency would be improved from 7.12% to 9.28% with respect to conventional Pt-film one. It was attributed to the enhanced catalytic surface from Pt nanoparticles and the improved conductivity due to the adjoining phenomenon of PtCNTs irradiated by laser. Moreover, the laser annealing could also promote the interface contact between CE and conductive glass. Therefore, such a simple laser-irradiated PtCNT network is promising for the future flexible DSSCs applications.

Chien, Yun-San, E-mail: u930347@oz.nthu.edu.tw; Fu, Wei-En [Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Yang, Po-Yu [Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan (China); Lee, I-Che; Chu, Chih-Chieh; Chou, Chia-Hsin; Cheng, Huang-Chung [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, Taiwan (China)

2014-02-03

358

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

NASA Technical Reports Server (NTRS)

In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar spectral irradiance reconstruction back to that period. As there is no direct measurement of the spectral irradiance for this period we discuss this methodology in light of the other proposed approaches available in the literature. The use of the cosmogenic isotope data provides a major advantage: it provides information about the solar activity over several thousands years. Using technology of today we can calibrate the solar irradiance against the activity and thus reconstruct it for the times when cosmogenic isotope data are available. This calibration can be re-accessed at any time, if necessary.

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

2011-01-01

359

Advanced Curation of Current and Future Extraterrestrial Samples  

NASA Technical Reports Server (NTRS)

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. Curation includes documentation, preservation, preparation, and distribution of samples. The current collections of extraterrestrial samples include: Lunar rocks / soils collected by the Apollo astronauts Meteorites, including samples of asteroids, the Moon, and Mars "Cosmic dust" (asteroid and comet particles) collected by high-altitude aircraft Solar wind atoms collected by the Genesis spacecraft Comet particles collected by the Stardust spacecraft Interstellar dust collected by the Stardust spacecraft Asteroid particles collected by the Hayabusa spacecraft These samples were formed in environments strikingly different from that on Earth. Terrestrial contamination can destroy much of the scientific significance of many extraterrestrial materials. In order to preserve the research value of these precious samples, contamination must be minimized, understood, and documented. In addition the samples must be preserved - as far as possible - from physical and chemical alteration. In 2011 NASA selected the OSIRIS-REx mission, designed to return samples from the primitive asteroid 1999 RQ36 (Bennu). JAXA will sample C-class asteroid 1999 JU3 with the Hayabusa-2 mission. ESA is considering the near-Earth asteroid sample return mission Marco Polo-R. The Decadal Survey listed the first lander in a Mars sample return campaign as its highest priority flagship-class mission, with sample return from the South Pole-Aitken basin and the surface of a comet among additional top priorities. The latest NASA budget proposal includes a mission to capture a 5-10 m asteroid and return it to the vicinity of the Moon as a target for future sampling. Samples, tools, containers, and contamination witness materials from any of these missions carry unique requirements for acquisition and curation. Some of these requirements represent significant advances over methods currently used. New analytical and screening techniques will increase the value of current sample collections. Improved web-based tools will make information on all samples more accessible to researchers and the public. Advanced curation of current and future extraterrestrial samples includes: Contamination Control - inorganic / organic Temperature of preservation - subfreezing / cryogenic Non-destructive preliminary examination - X-ray tomography / XRF mapping / Raman mapping Microscopic samples - handling / sectioning / transport Special samples - unopened lunar cores Informatics - online catalogs / community-based characterization.

Allen, Carlton C.

2013-01-01

360

UV solar irradiance with cloudiness at high latitudes; a comparison between radiometer GUV 511 and model"s output  

NASA Astrophysics Data System (ADS)

Solar UV irradiance measurements in Antarctica are often carried out by automatic or semiautomatic equipment. The unattended way of managing instruments needs accurate knowledge of the parameters affecting experimental data, among which cloudiness plays a fundamental role. A moderate-band multifilter radiometer and a total sky camera were installed for a test in the Italian Antarctic base (Terra Nova Bay, 74.07°S, 164.08°E) during the summer campaign 2002 - 2003. This paper shows preliminary results on the radiometer spectral data and a comparison with modelled spectral irradiances. Moreover, the radiometer integrated irradiance, computed by means of a new model, was compared with the updated Green model integrated irradiance, corrected by a cloud factor obtained from the sky camera images. Results showed good agreement on the integrated irradiances but poor results, except for 305 nm, when spectral values were analyzed.

Rafanelli, Claudio; Anav, Andrea; Di Menno, Ivo; Di Menno, Massimo; Casale, Giuseppe R.

2003-11-01

361

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

SciTech Connect

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

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

1987-06-01

362

Detection of solar wind-produced water in irradiated rims on silicate minerals.  

PubMed

The solar wind (SW), composed of predominantly ?1-keV H(+) ions, produces amorphous rims up to ?150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H(+) may react with oxygen in the minerals to form trace amounts of hydroxyl (-OH) and/or water (H2O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If -OH or H2O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system. PMID:24449869

Bradley, John P; Ishii, Hope A; Gillis-Davis, Jeffrey J; Ciston, James; Nielsen, Michael H; Bechtel, Hans A; Martin, Michael C

2014-02-01

363

Evaporation and solar irradiance as regulators of sea surface temperature in annual and interannual changes  

NASA Technical Reports Server (NTRS)

Seven years of net surface solar irradiance (S) derived from cloud information provided by the International Satellite Cloud Climatology Project (ISCCP) and 4 years of surface latent heat flux (E) derived from the observations of the special sensor microwave imager (SSM/I) were used to examine the relation between surface heat fluxes and sea surface temperature (T(sub s)) in their global geographical distribution, seasonal cycle, and interannual variation. The relations of seasonal changes imply that evaporation cooling is significant over most of the ocean and that solar heating is the main drive for the change of T(sub s) away from the equatorial wave guide where ocean dynamics may be more important. However, T(sub s) is not the most direct and significant factor in the seasonal changes of S and E over most of the ocean; the solar incident angle may be more important to S, and wind speed and air humidity are found to correlate better with E. Significant local correlations between anomalies of T(sub s) and S and between anomalies of T(sub s) and E are found in the central equatorial Pacific; both types of correlation are negative. The influence of ocean dynamics in changing T(sub s) in the tropical ocean cannot be ignored.

Liu, W. Timothy; Zhang, Anzhen; Bishop, James K. B.

1994-01-01

364

Detection of solar wind-produced water in irradiated rims on silicate minerals  

PubMed Central

The solar wind (SW), composed of predominantly ?1-keV H+ ions, produces amorphous rims up to ?150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H+ may react with oxygen in the minerals to form trace amounts of hydroxyl (?OH) and/or water (H2O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If ?OH or H2O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system. PMID:24449869

Bradley, John P.; Ishii, Hope A.; Gillis-Davis, Jeffrey J.; Ciston, James; Nielsen, Michael H.; Bechtel, Hans A.; Martin, Michael C.

2014-01-01

365

The response of middle atmospheric ozone to solar UV irradiance variations with a period of 27 days  

NASA Technical Reports Server (NTRS)

A one-dimensional photochemical-dynamical-radiative time-dependent model was used to study the response of middle atmospheric temperature and ozone to solar UV irradiance variations with the period of 27 days. The model solar UV O(x), HO(x), NO(x), and CIO(x)families and modeled solar UV variations. The amplitude of the primary temperature response to the solar UV variation is plus 0.4 K at 85-90 km with a phase lag of about 6 days. A secondary maximum response of plus 0.3 K at 45-50 km appears with a phase lag of 1 day. There is a maximum positive ozone response to the 27-day solar UV oscillation of 2.5 percent at 80-90 km with a phase lag of about 10 days after the solar irradiance maximum. At 70 km the ozone response is about 1.2 percent and is out of phase with the solar variation. In the upper stratosphere (40-50 km) the relative ozone variation is small, about 0.2 percent to 0.3 percent, and there is a negative phase of about 4 days between the ozone and solar oscillations. These oscillations are in phase in the middle stratosphere (35-40 km) where there is again a maximum relative response of about 0.6 percent. The reasons for these ozone amplitude and phase variations are discussed.

Chen, LI; Brasseur, Guy; London, Julius

1994-01-01

366

Searching for extraterrestrial intelligence - The ultimate exploration  

NASA Technical Reports Server (NTRS)

A survey highlighting the central issues of the SETI program (Search for Extraterrestrial Intelligence), including its rationale, scope, search problems, and goals is presented. Electromagnetic radiation is suggested as the most likely means via which knowledge of extraterrestrial intelligence will be obtained, and the variables governing these signals are discussed, including: signal frequency and polarization, state, possible coordinates, and signal duration. The modern history of SETI and NASA's involvement is briefly reviewed, and the search strategies used by the Jet Propulsion Laboratory and the Ames Research Center are discussed and compared. Some of the potential scientific and cultural impacts of the SETI program are mentioned, noting advancements in technological, biological, and chemical research.

Black, D.; Tarter, J.; Cuzzi, J. N.; Conners, M.; Clark, T. A.

1977-01-01

367

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

NASA Technical Reports Server (NTRS)

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

Platnick, Steven; Fontenla, Juan M.

2006-01-01

368

Detailed calculations of the solar irradiance and optimized set-ups of Sun collectors, by the example of central Mexico  

Microsoft Academic Search

In the near future, the use of sustainable energy will become ever more important. Political support and strongly growing demand will make it more economic and affordable. Hence, more detailed theoretical calculations for the optimization of the geometrical installation of collector systems are now most useful. In this work, we describe a way to calculate the time-dependent solar irradiance. We

Carsten Holtfort; Isabel Delgadillo-Holtfort; Klaus-Peter Schröder

2012-01-01

369

Detailed calculations of the solar irradiance and optimized set-ups of Sun collectors, by the example of central Mexico  

Microsoft Academic Search

In the near future, the use of sustainable energy will become ever more important. Political support and strongly growing demand will make it more economic and affordable. Hence, more detailed theoretical calculations for the optimization of the geometrical installation of collector systems are now most useful. In this work, we describe a way to calculate the time-dependent solar irradiance. We

Carsten Holtfort; Isabel Delgadillo-Holtfort; Klaus-Peter Schröder

2010-01-01

370

Defects and annealing studies in 1-Me electron irradiated (AlGa)As-GaAs solar cells  

NASA Technical Reports Server (NTRS)

The deep-level defects and recombination mechanisms in the one-MeV electron irradiated (AlGa)As-GaAs solar cells under various irradiation and annealing conditions are discussed. Deep-level transient spectroscopy (DLTS) and capacitance-voltage (CV) techniques were used to determine the defect and recombination parameters such as energy levels and defect density, carrier capture cross sections and lifetimes for both electron and hole traps as well as hole diffusion lengths in these electron irradiated GaAs solar cells. GaAs solar cells used in this study were prepared by the infinite solution melt liquid phase epitaxial (LPE) technique at Hughes Research Lab., with (Al0.9Ga0.1)-As window layer, Be-diffused p-GaAs layer on Sn-doped n-GaAs or undoped n-GaAs active layer grown on n(+)-GaAs substrate. Mesa structure with area of 5.86x1000 sq cm was fabricated. Three different irradiation and annealing experiments were performed on these solar cells.

Li, S. S.; Wang, W. L.; Loo, R. Y.; Rahilly, W. P.

1982-01-01

371

Using direct normal irradiance models and utility electrical loading to assess benefit of a concentrating solar power plant  

Technology Transfer Automated Retrieval System (TEKTRAN)

Direct normal irradiance (DNI) is required to evaluate performance of concentrating solar energy systems. The objective of this paper is to analyze the effect of time interval (e.g. year, month, hour) on the accuracy of three different DNI models. The DNI data were measured at three different labora...

372

Life Cycle Analysis to estimate the environmental impact of residential photovoltaic systems in regions with a low solar irradiation  

Microsoft Academic Search

Photovoltaic installations (PV-systems) are heavily promoted in Europe. In this paper, the Life Cycle Analysis (LCA) method is used to find out whether the high subsidy cost can be justified by the environmental benefits. Most existing LCAs of PV only use one-dimensional indicators and are only valid for regions with a high solar irradiation. This paper, however, presents a broad

Ruben Laleman; Johan Albrecht; Jo Dewulf

2011-01-01

373

Organic synthesis via irradiation and warming of ice grains in the solar nebula.  

PubMed

Complex organic compounds, including many important to life on Earth, are commonly found in meteoritic and cometary samples, though their origins remain a mystery. We examined whether such molecules could be produced within the solar nebula by tracking the dynamical evolution of ice grains in the nebula and recording the environments to which they were exposed. We found that icy grains originating in the outer disk, where temperatures were less than 30 kelvin, experienced ultraviolet irradiation exposures and thermal warming similar to that which has been shown to produce complex organics in laboratory experiments. These results imply that organic compounds are natural by-products of protoplanetary disk evolution and should be important ingredients in the formation of all planetary systems, including our own. PMID:22461502

Ciesla, Fred J; Sandford, Scott A

2012-04-27

374

ARIMA representation for daily solar irradiance and surface air temperature time series  

NASA Astrophysics Data System (ADS)

Autoregressive integrated moving average (ARIMA) models are used to compare long-range temporal variability of the total solar irradiance (TSI) at the top of the atmosphere (TOA) and surface air temperature series. The comparison shows that one and the same type of the model is applicable to represent the TSI and air temperature series. In terms of the model type surface air temperature imitates closely that for the TSI. This may mean that currently no other forcing to the climate system is capable to change the random walk type variability established by the varying activity of the rotating Sun. The result should inspire more detailed examination of the dependence of various climate series on short-range fluctuations of TSI.

Kärner, Olavi

2009-06-01

375

Effects of space vacuum and solar ultraviolet irradiation (254 nanometers) on the colony forming ability of Bacillus subtilis spores  

NASA Technical Reports Server (NTRS)

Bacillus subtilis spores are highly resistant to harsh environments. Therefore, in the Apollo 16 Microbial Response to Space Environment Experiment (M191), these spores were exposed to space vacuum or solar ultraviolet irradiation, or both, to estimate the change of survival for terrestrial organisms in space. The survival of the spores was determined in terms of colony-forming ability. Comparison of the flight results with results of simulation experiments on earth applying high vacuum or ultraviolet irradiation, or both, revealed no remarkable difference. Simultaneous exposure to both these space factors resulted in a synergistic effect (that is, an ultraviolet supersensitivity). Therefore, the change of survival in space is assumed to depend on the degree of protection against solar ultraviolet irradiation.

Buecker, H.; Horneck, G.; Wollenhaupt, H.

1973-01-01

376

Oh emission regions and extraterrestrial intelligence  

Microsoft Academic Search

In a stimulating review paper BARRETT (1967) has tentatively broached the possibility that the galactic 18-cm hydroxyl emission might actually be part of a communications network among extraterrestrial civilizations. The high-intensity, puzzling ratios of individual lines, narrow bandwidths, origin from regions of small angular size, strong polarization, and possible time variation are the sort of properties one might associate with

Carl Sagan

1968-01-01

377

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

) black holes/wormholes (c) sociological implications of first contact (d) YOUR CHOICE HERE not clearly SAS Honors Seminar 256: Extraterrestrial Life 11/22/2011 #12; Where are the Pioneers for Life on Mars Sociological Implications of First Contact Congressional Funding for Astrobiological

Baker, Andrew J.

378

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

) multiverse theory (b) black holes/wormholes (c) sociological implications of first contact (d) astrobiology SAS Honors Seminar 256: Extraterrestrial Life 11/29/2011 #12; Reading for Thursday Review: Searching for Life on Mars Practical Implications of the Fermi Paradox Congressional Funding

Baker, Andrew J.

379

The Future, Extraterrestrial Space Humanization and Sociology.  

ERIC Educational Resources Information Center

This paper suggests that sociologists should become actively involved with the study of the future as a means for revitalizing the profession of sociology. One aspect of the future that may be most exciting and challenging is the development of human society and culture in extraterrestrial human communities. A unique combination of technological…

MacDaniel, William E.

380

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

and Life on Europa Carroll ­ The Future of Space Exploration Forrest ­ Martian Meteorites Gabbay SAS Honors Seminar 256: Extraterrestrial Life 12/6/2011 #12; Reading for Thursday ­ Searching for Life on Mars Berger ­ Practical Implications of the Fermi Paradox Blaha ­ Extremophiles

Baker, Andrew J.

381

SAS Honors Seminar 259: Extraterrestrial Life  

E-print Network

certainty comet or disintegrating asteroid? http://wwwth.bo.infn.it/tunguska/ #12; Impact craters SAS Honors Seminar 259: Extraterrestrial Life 10/29/2008 #12; Tunguska event http://wwwth.bo.infn.it/tunguska/ 2004 image of 1908 site 80 million trees felled over an area of ~2150 km2 #12; Tunguska event 2005

Baker, Andrew J.

382

Strategy for the search for extraterrestrial intelligence  

Microsoft Academic Search

The problem of detection and investigation of extraterrestrial intelligence is exceptionally important for mankind from a practical standpoint, for its culture and philosophy. Its importance can even be compared to the importance of the main problems confronting our civilization at the present time, since the information obtained as a result of the discovery of intelligence in the Universe will probably

N. S. Kardashev

1979-01-01

383

SETI: Search for ExtraTerrestrial Intelligence  

E-print Network

SETI: Search for ExtraTerrestrial Intelligence I know perfectly well that at this moment the whole, The Madwoman of Chaillot #12;Search Strategies Suppose you find a civilization. You want to communicate. How? #12;Options Passive SETI: Listen Active SETI: Transmit #12;Search Strategies There are two issues: A

Walter, Frederick M.

384

The Search for ExtraTerrestrial Intelligence  

Microsoft Academic Search

Aliens abound on the movie screens, but in reality we are still trying to find out if we share our universe with other sentient creatures. Intelligence is very difficult to define, and impossible to directly detect over interstellar distances. Therefore, SETI, the search for extraterrestrial intelligence, is actually an attempt to detect evidence of another distant technology. If we find

J. Tarter

1998-01-01

385

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

386

NASA contemplates radio Search for Extraterrestrial Intelligence  

Microsoft Academic Search

The paper examines the Search for Extra-terrestrial Intelligence (SETI), with emphasis on the nature of the SETI advisory panel, the Project Cyclops (a giant array of radio telescopes whose performance would imitate that of a single radio dish up to 5 km in diameter) the possibility of an orbiting SETI system assembled by Space Shuttle, and the possibility of a

R. Sheaffer

1976-01-01

387

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

NASA Astrophysics Data System (ADS)

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 full MOD5 spectral range, from 0.2 um to far-IR. MODTRAN-5, MODerate resolution radiance and TRANsmittance code, has been developed collaboratively by Air Force Research Laboratory and Spectral Sciences, Inc., with history dating back to LOWTRAN. It includes approximations for all local thermodynamic equilibrium terms associated with molecular, cloud, aerosol and surface components for emission, scattering, and reflectance, including multiple scattering, refraction and a statistical implementation of Correlated-k averaging. The band model is based on 0.1 cm-1 (also 1.0, 5.0 and 15.0 cm-1 statistical binning for line centers within the interval, captured through an exact formulation of the full Voigt line shape. Spectroscopic parameters are from HITRAN 2004 with user-defined options for additional gases. Recent validation studies show MOD5 replicates line-by-line brightness temperatures to within ~0.02ºK average and <1.0ºK RMS. MOD5 can then serve as a surrogate for a variety of perturbation studies, including the two modes for the solar source function, Io. (1) Data from the Solar Radiation and Climate Experiment (SORCE) satellite mission provide state-of-the-art measurements of UV, visible, near-IR, plus total solar radiation, on near real-time basis. These internally consistent estimates of Sun's output over solar rotation and longer time scales are valuable inputs for studying effects of Sun's radiation on Earth's atmosphere and climate. When solar rotation encounters bright plage and dark sunspots, relative variations are expected to be very small in visible wavelengths, although absolute power is substantial. SORCE's Spectral Irradiance Monitor measurements are readily included in comparative MOD5 calculations. (2) The embedded solar irradiance within MOD5 must be compatible with the chosen band model resolution binning. By matching resolutions some issues related to the correlated-k band model parameterizations can be tested. Two high resolution solar irradiances, the MOD5 default irradiance (Kurucz) and a new compilation associated with Solar Radiation Physical Modeling project (Fontenla), are compared to address the potential impact of discrepancies between any sets of irradiances. The magnitude of solar variability, as measured and calculated, can lead to subtle changes in heating/cooling rates throughout the atmosphere, as a function of altitude and wavelength. By holding chemical & dynamical responses constant, only controlled distributions of absorbing gases, aerosols and clouds will contribute to observed 1st order radiative effects.

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

2006-12-01

388

Total ozone column, water vapour and aerosol effects on erythemal and global solar irradiance in Marsaxlokk, Malta  

NASA Astrophysics Data System (ADS)

Observations of erythemal (UVER; 280-400 nm) and total solar shortwave irradiance (SW; 305-2800 nm), total ozone column (TOC), water vapour column (w), aerosol optical depth (AOD) and Ångström exponent (?) were carried out at Marsaxlokk, in south-east Malta. These measurements were recorded during a measurement campaign between May and October 2012, aimed at studying the influence of atmospheric compounds on solar radiation transfer through the atmosphere. The effects of TOC, AOD and w on UVER and SW (global, diffuse and direct) irradiance were quantified using irradiance values under cloud-free conditions at different fixed solar zenith angles (SZA). Results show that UVER (but not SW) irradiance correlates well with TOC. UVER variations ranged between -0.24% DU-1 and -0.32% DU-1 with all changes being statistically significant. Global SW irradiance varies with water vapour column between -2.44% cm-1 and -4.53% cm-1, these results proving statistically significant and diminishing when SZA increases. The irradiance variations range between 42.15% cm-1 and 20.30% cm-1 for diffuse SW when SZA varies between 20° and 70°. The effect of aerosols on global UVER is stronger than on global SW. Aerosols cause a UVER reduction of between 28.12% and 52.41% and a global SW reduction between 13.46% and 41.41% per AOD550 unit. Empirical results show that solar position plays a determinant role, that there is a negligible effect of ozone on SW radiation, and stronger attenuation by aerosol particles in UVER radiation.

Bilbao, Julia; Román, Roberto; Yousif, Charles; Mateos, David; de Miguel, Argimiro

2014-12-01

389

Sources of Differences in On-Orbit Total Solar Irradiance Measurements and Description of Proposed Laboratory Intercomparison  

NASA Technical Reports Server (NTRS)

There is a 5 W/sq m (about 0.35 %) difference between current on-orbit Total Solar Irradiance (TSI) measurements. On 18-20 July 2005, a workshop was held at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland that focused on understanding possible reasons for this difference, through an examination of the instrument designs, calibration approaches, and appropriate measurement equations. The instruments studied in that workshop included the Active Cavity Radiometer Irradiance Monitor III (ACRIM III) on the Active Cavity Radiometer Irradiance Monitor SATellite (ACRIMSAT), the Total Irradiance Monitor (TIM) on the Solar Radiation and Climate Experiment (SORCE), the Variability of solar IRradiance and Gravity Oscillations (VIRGO) on the Solar and Heliospheric Observatory (SOHO), and the Earth Radiation Budget Experiment (ERBE) on the Earth Radiation Budget Satellite (ERBS). Presentations for each instrument included descriptions of its design, its measurement equation and uncertainty budget, and the methods used to assess on-orbit degradation. The workshop also included a session on satellite- and ground-based instrument comparisons and a session on laboratory-based comparisons and the application of new laboratory comparison techniques. The workshop has led to investigations of the effects of diffraction and of aperture area measurements on the differences between instruments. In addition, a laboratory-based instrument comparison is proposed that uses optical power measurements (with lasers that underEll the apertures of the TSI instruments), irradiance measurements (with lasers that overfill the apertures of the TSI instrument), and a cryogenic electrical substitution radiometer as a standard for comparing the instruments. A summary of the workshop and an overview of the proposed research efforts are presented here.

Butler, J.J.; Johnson, B. C.; Rice, J. P.; Shirley, E. L.; Barnes, R.A.

2008-01-01

390

EPR and transient capacitance studies on electron-irradiated silicon solar cells  

NASA Technical Reports Server (NTRS)

One and two ohm-cm solar cells irradiated with 1 MeV electrons at 30 C were studied using both EPR and transient capacitance techniques. In 2 ohm-cm cells, Si-G6 and Si-G15 EPR spectra and majority carrier trapping levels at (E sub V + 0.23) eV and (E sub V + 0.38) eV were observed, each of which corresponded to the divacancy and the carbon-oxygen-vacancy complex, respectively. In addition, a boron-associated defect with a minority carrier trapping level at (E sub C -0.27) eV was observed. In 1 ohm-cm cells, the G15 spectrum and majority carrier trap at (E sub V + 0.38) eV were absent and an isotropic EPR line appeared at g = 1.9988 (+ or - 0.0003); additionally, a majority carrier trapping center at (E sub V + 0.32) eV, was found which could be associated with impurity lithium. The formation mechanisms of these defects are discussed according to isochronal annealing data in electron-irradiated p-type silicon.

Lee, Y. H.; Cheng, L. J.; Mooney, P. M.; Corbett, J. W.

1977-01-01

391

Correlation between Displacement Damage Dose and Proton Irradiation Effects on GaInP/GaAs/Ge Space Solar Cells  

NASA Astrophysics Data System (ADS)

The irradiation effects of 0.28-2.80 MeV protons on GaInP/GaAs/Ge solar cells have been analysed, and then correlated with the displacement damage dose. The results of I-V and spectral response measurements, combined with the SRIM-derived vacancies produced rates, show that the degradation of the solar cells is largely determined by the displacement damage of the GaAs sub-cell. Thus the SRIM-derived NIEL values for protons in the GaAs sub-cell are used to calculate the displacement damage dose. It is shown that the irradiation effects of the solar cells caused by protons at different energies are correlated well with the aid of displacement damage dose.

Liu, Yun-Hong; Wang, Rong; Cui, Xin-Yu; Wang, Yong-Xia

2009-02-01

392

Reconstruction and prediction of the total solar irradiance: From the Medieval Warm Period to the 21st century  

NASA Astrophysics Data System (ADS)

Total solar irradiance is the primary energy source of the Earth’s climate system and therefore its variations can contribute to natural climate change. This variability is characterized by, among other manifestations, decadal and secular oscillations, which has led to several attempts to estimate future solar activity. Of particular interest now is the fact that the behavior of the solar cycle 23 minimum has shown an activity decline not previously seen in past cycles for which spatial observations exist: this could be signaling the start of a new grand solar minimum. The estimation of solar activity for the next hundred years is one of the current problems in solar physics because the possible occurrence of a future grand solar minimum will probably have an impact on the Earth’s climate. In this study, using the PMOD and ACRIM TSI composites, we have attempted to estimate the TSI index from year 1000 AD to 2100 AD based on the Least Squares Support Vector Machines, which is applied here for the first time to estimate a solar index. Using the wavelet transform, we analyzed the behavior of the total solar irradiance time series before and after the solar grand minima. Depending on the composite used, PMOD (or ACRIM), we found a grand minimum for the 21st century, starting in ?2004 (or 2002) and ending in ?2075 (or 2063), with an average irradiance of 1365.5 (or 1360.5) Wm±1?=0.3 (or 0.9) Wm. Moreover, we calculated an average radiative forcing between the present and the 21st century minima of ?-0.1 (or -0.2) Wm, with an uncertainty range of -0.04 to -0.14 (or -0.12 to -0.33) Wm. As an indicator of the TSI level, we calculated its annual power anomalies; in particular, future solar cycles from 24 to 29 have lower power anomalies compared to the present, for both models. We also found that the solar activity grand minima periodicity is of 120 years; this periodicity could possibly be one of the principal periodicities of the magnetic solar activity not so previously well recognized. The negative (positive) 120-year phase coincides with the grand minima (maxima) of the 11-year periodicity.

Velasco Herrera, V. M.; Mendoza, B.; Velasco Herrera, G.

2015-01-01

393

American Solar Energy Society Proc. ASES Annual Conference, Phoenix, AZ, May 2010 IMPROVING THE PERFORMANCE OF SATELLITE-TO-IRRADIANCE MODELS USING  

E-print Network

© American Solar Energy Society ­ Proc. ASES Annual Conference, Phoenix, AZ, May 2010 IMPROVING;© American Solar Energy Society ­ Proc. ASES Annual Conference, Phoenix, AZ, May 2010 between the snow-to-irradiance model designed to complement the existing SUNY model used in the US National Solar Resource Data Base

Perez, Richard R.

394

A new empirical approach in the Search for Extraterrestrial Intelligence: Astrobiological nonlocality at the cosmological level  

Microsoft Academic Search

Over a period of several decades a concerted effort has been made to\\u000adetermine whether intelligent life exists outside of our solar system, known as\\u000athe Search for Extraterrestrial Intelligence or SETI. This has been based\\u000aprimarily upon attempting to intercept possible radio transmissions at\\u000adifferent frequencies with arrays of radio telescopes. In addition,\\u000aastrophysical observations have also been undertaken

Fred H. Thaheld

2006-01-01

395

Search for Extraterrestrial Intelligence at 22 GHz with the Very Large Array  

Microsoft Academic Search

We have conducted a direct Search for Extraterrestrial Intelligence at the Water Maser frequency, 22.235 GHz, using the Very Large Array. The targets were 13 solar-type stars that were known to host exoplanetary systems. In all cases, the RMS limits of the flux density, 20 mJy (5sigma), were sufficient to rule out any omnidirectional transmitters of the same power as

Toshimichi Shirai; Tomoaki Oyama; Hiroshi Imai; Shinsuke Abe

2004-01-01

396

Extraterrestrial Life: Problem Set #1 Solutions 1) Explain briefly how the terrestrial planets (such as the Earth) differ from  

E-print Network

Extraterrestrial Life: Problem Set #1 Solutions 1) Explain briefly how the terrestrial planets. The atmospheres of the terrestrial planets make up a very small fraction of the mass. The giant planets have planets all lie in the outer Solar System, exterior to the orbits of the terrestrial planets

Armitage, Phil

397

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

398

Extraterrestrial organic matter: a review  

NASA Technical Reports Server (NTRS)

We review the nature of the widespread organic material present in the Milky Way Galaxy and in the Solar System. Attention is given to the links between these environments and between primitive Solar System objects and the early Earth, indicating the preservation of organic material as an interstellar cloud collapsed to form the Solar System and as the Earth accreted such material from asteroids, comets and interplanetary dust particles. In the interstellar medium of the Milky Way Galaxy more than 100 molecular species, the bulk of them organic, have been securely identified, primarily through spectroscopy at the highest radio frequencies. There is considerable evidence for significantly heavier organic molecules, particularly polycyclic aromatics, although precise identification of individual species has not yet been obtained. The so-called diffuse interstellar bands are probably important in this context. The low temperature kinetics in interstellar clouds leads to very large isotopic fractionation, particularly for hydrogen, and this signature is present in organic components preserved in carbonaceous chondritic meteorites. Outer belt asteroids are the probable parent bodies of the carbonaceous chondrites, which may contain as much as 5% organic material, including a rich variety of amino acids, purines, pyrimidines, and other species of potential prebiotic interest. Richer in volatiles and hence less thermally processed are the comets, whose organic matter is abundant and poorly characterized. Cometary volatiles, observed after sublimation into the coma, include many species also present in the interstellar medium. There is evidence that most of the Earth's volatiles may have been supplied by a 'late' bombardment of comets and carbonaceous meteorites, scattered into the inner Solar System following the formation of the giant planets. How much in the way of intact organic molecules of potential prebiotic interest survived delivery to the Earth has become an increasingly debated topic over the last several years. The principal source for such intact organics was probably accretion of interplanetary dust particles of cometary origin.

Irvine, W. M.

1998-01-01

399

Artificial neural networks for the generation of direct normal solar annual irradiance synthetic series  

NASA Astrophysics Data System (ADS)

The use of concentrators implies that CPV systems only work with the Direct Normal Irradiance (DNI). So it is necessary to know DNI data in order to estimate the energy that will be produced by the system, perform economic analysis, supervise plant operation, etc. However, DNI Typical Meteorological Year datasets are expensive and rarely available due to the cost and sophistication of measurement devices and data processing requirements. Particularly, there is a lack of data on the Sunbelt countries, which are more favorable for the use of CPV. In this work, an artificial neural network is used for the generation of DNI hourly time series for some Spanish locations. The model was trained and tested with different locations and different year's data. Although several authors have proposed different methods for the generation of solar radiation synthetic series, these methods are for global radiation and flat panel, nevertheless, we calculate them for direct normal solar radiation and used for CPV systems. A Multilayer Perceptron is explained, looking over the first rudimentary initial version and the last more elaborated final version. Finally, an application of this methodology is presented.

Rodrigo, J.; Hontoria, L.; Almonacid, F.; Fernández, Eduardo F.; Rodrigo, P. M.; Pérez-Higueras, P. J.

2012-10-01

400

Development of Wide Field-of-View Cavity Radiometer for Solar Simulator Use and Intercomparison between Irradiance Measurements based on the World Radiometer Reference and Electrotechnical Laboratory Scales  

NASA Astrophysics Data System (ADS)

We have developed wide field-of-view cavity radiometers which can be used under the solar simulator radiation and are traceable to the World Radiometer Reference (WRR) scale. Simultaneous measurements of direct solar radiation were performed with these new instruments and the official standard radiometer PMO-6 which was used to maintain the WRR scale in Japan. The results show good agreement within the range of accuracy of the instruments and clarify the relationship of the new instruments to the WRR scale. In addition, the solar simulator irradiance measured by the new instruments was compared with the integrated irradiance measured by the spectroradiometer calibrated against the Electrotechnical Laboratory (ETL) spectral irradiance scale which was employed for the reference cell calibration in Japan. Consequently, we found that the irradiance based on the WRR scale was about 2% lower than the integrated irradiance based on the ETL spectral irradiance scale.

Shimokawa, Ryuichi; Ikeda, Hirosi; Miyake, Yukiharu; Igari, Sanekazu

2002-08-01

401

Wavelength dependence of solar irradiance enhancement during X-class flares and its influence on the upper atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

402

Electronic properties of deep-level defects in proton irradiated AlGaAs-GaAs solar cells  

NASA Technical Reports Server (NTRS)

Deep level transient spectroscopy and capacitance voltage techniques as well as analysis of the forward current voltage (I-V) characteristics and SEM-EIC data were carried out for proton irradiated GaAs solar cells over a wide range of proton energies and proton fluences. Defect and recombination parameters such as defect energy levels and density, carrier capture cross sections and lifetimes as well as diffusion lengths in the undoped n-GaAs LPE layers were determined. Good correlation between these defect parameters and solar cell performance parameters was obtained for GaAs solar cells irradiated by 200 and 290 KeV protons. It was found that 200 to 290 KeV protons will produce the most defects and damages to the GaAs solar cell structure used. The influence of the low temperature (200 to 400 C) periodic thermal annealing on the deep level defects and the performance of the 200 KeV proton irradiated cells is discussed.

Li, S. S.

1981-01-01

403

Impact of aerosols on the forecast accuracy of solar irradiance calculated by a numerical weather prediction model  

NASA Astrophysics Data System (ADS)

The impact of aerosols on the forecast accuracy of solar irradiance calculated by a fine-scale, one day-ahead, and operational numerical weather prediction model (NWP) is investigated in this study. In order to investigate the impact of aerosols only, the clear sky period is chosen, which is defined as when there are no clouds in the observation data and in the forecast data at the same time. The evaluation of the forecast accuracy of the solar irradiance is done at a single observation point that is sometimes affected by aerosol events. The analysis period is one year from April 2010 to March 2011. During the clear sky period, the root mean square errors (RMSE) of the global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI) are 40.0 W m-2, 84.0 Wm-2, and 47.9 W m-2, respectively. During one extreme event, the RMSEs of the GHI, DNI, and DHI are 70.1 W m-2, 211.6 W m-2, and 141.7 W m-2, respectively. It is revealed that the extreme events were caused by aerosols such as dust or haze. In order to investigate the impact of the aerosols, the sensitivity experiments of the aerosol optical depth (AOD) for the extreme events are executed. The best result is obtained by changing the AOD to 2.5 times the original AOD. This changed AOD is consistent with the satellite observation. Thus, it is our conclusion that an accurate aerosol forecast is important for the forecast accuracy of the solar irradiance.

Shimose, Ken-ichi; Ohtake, Hideaki; Fonseca, Joao Gari da Silva; Takashima, Takumi; Oozeki, Takashi; Yamada, Yoshinori

2014-10-01

404

Solar radiation based calibration of a short-wave ir radiometer and a comparison of exoatmospheric solar spectral irradiance data sets  

NASA Astrophysics Data System (ADS)

We have performed an absolute calibration comparison between the Sun and a NIST-calibrated spectral irradiance standard lamp. The comparison at seven bands ranging from 1.2 to 2.3 ?m was made using a highly stable Short Wave IR Transfer Radiometer. The experiment consisted of laboratory and outdoor measurements of an irradiated diffusely reflecting panel. Outdoors, simultaneous atmospheric transmittance measurements were also obtained in order to correct for atmospheric effects. The results were used to compare three absolute exo-atmospheric solar spectral irradiance data sets currently used in various remote sensing applications to a NIST traceable radiometric calibration. The comparison with the limited set of recently produced SORCE-SIM data showed almost no differences at 1.2 and 1.6 ?m however, the comparison with three other data sets showed larger differences.

Zalewski, Edward; Cattrall, Christopher

2005-08-01

405

SOLAR AND METEOROLOGICAL SURFACE OBSERVATION NETWORK (SAMSON) FOR NC, VA  

EPA Science Inventory

Solar and Meteorological Surface Observational Network (SAMSON) v1.0 data for 6 NWS stations in North Carolina and 4 in Virginia. Hourly solar elements are: extraterrestrial horizontal and extraterrestrial direct normal radiation; global, diffuse, and direct normal radiation. Met...

406

Analytical SuperSTEM for extraterrestrial materials research  

NASA Astrophysics Data System (ADS)

Electron-beam studies of extraterrestrial materials with significantly improved spatial resolution, energy resolution, and sensitivity are enabled using a 300 keV SuperSTEM scanning transmission electron microscope(STEM) with a monochromator and two spherical aberration correctors. The improved technical capabilities enable analyses previously not possible. Mineral structures can be directly imaged and analyzed with single-atomic-column resolution, liquids, and implanted gases can be detected, and UV-VIS optical properties can be measured. Detection limits for minor/trace elements in thin (<100 nm thick) specimens are improved such that quantitative measurements of some extend to the sub-500 ppm level. Electron energy-loss spectroscopy (EELS) can be carried out with 0.10-0.20 eV energy resolution and atomic-scale spatial resolution such that variations in oxidation state from one atomic column to another can be detected. Petrographic mapping is extended down to the atomic scale using energy dispersive X-ray spectroscopy (EDS) and energy-filtered transmission electron microscopy (EFTEM) imaging