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1

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

2

Radio propagation through solar and other extraterrestrial ionized media  

NASA Technical Reports Server (NTRS)

The present S- and X-band communications needs in deep space are addressed to illustrate the aspects which are affected by propagation through extraterrestrial plasmas. The magnitude, critical threshold, and frequency dependence of some eight propagation effects for an S-band propagation path passing within 4 solar radii of the Sun are described. The theory and observation of propagation in extraterrestrial plasmas are discussed and the various plasma states along a near solar propagation path are illustrated. Classical magnetoionic theory (cold anisotropic plasma) is examined for its applicability to the path in question. The characteristics of the plasma states found along the path are summarized and the errors in some of the standard approximations are indicated. Models of extraterrestrial plasmas are included. Modeling the electron density in the solar corona and solar wind, is emphasized but some cursory information on the terrestrial planets plus Jupiters is included.

Smith, E. K.; Edelson, R. E.

1980-01-01

3

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

4

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

5

Solar irradiance since 1874 revisited  

Microsoft Academic Search

We reconstruct the solar irradiance since 1874 employing an evolved version of previously published models and improved sunspot and facular data. A good correlation between reconstructed irradiance and Earth's global air temperature on time scales longer than the solar cycle is obtained and, in contrast to many earlier models, solar irradiance does not on average lag behind global temperature prior

S. K. Solanki; M. Fligge

1998-01-01

6

4, 84398469, 2004 Solar irradiance  

E-print Network

ACPD 4, 8439­8469, 2004 Solar irradiance W. Gurlit et al. Title Page Abstract Introduction-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements W. Gurlit1 , H. B¨osch2, * , H

Paris-Sud XI, Université de

7

Solar Cycle Variation in Solar Irradiance  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

8

Solar cycle variation in solar irradiance  

E-print Network

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

Yeo, K L; Solanki, S K

2014-01-01

9

Observations of solar irradiance variability  

Microsoft Academic Search

High-precision measurements of total solar irradiance, made by the active cavity radiometer irradiance monitor on the Solar Maximum Mission satellite, show the irradiance to have been variable throughout the first 153 days of observations. The corrected data resolve orbit-to-orbit variations with uncertainties as small as 0.001 percent. Irradiance fluctuations are typical of a band-limited noise spectrum with high-frequency cutoff near

R. C. Willson; M.. Janssen; H. S. Hudson; G. A. Chapman; S. Bulkis

1981-01-01

10

The LASP Interactive Solar IRradiance Datacenter (LISIRD)  

Microsoft Academic Search

The Laboratory for Atmospheric and Space Physics (LASP) has been making space-based measurements of solar irradiance for many decades, and thus has established an extensive catalog of past and ongoing space- based solar irradiance measurements. In order to maximize the accessibility and usability of solar irradiance data and information from multiple missions, LASP is developing the LASP Interactive Solar IRradiance

C. K. Pankratz; D. M. Lindholm; M. Snow; B. Knapp; D. Woodraska; B. Templeman; T. N. Woods; F. G. Eparvier; J. Fontenla; J. Harder; W. E. McClintock

2007-01-01

11

Fluid-induced organic synthesis in the solar nebula recorded in extraterrestrial dust from meteorites.  

PubMed

Isotopically anomalous carbonaceous grains in extraterrestrial samples represent the most pristine organics that were delivered to the early Earth. Here we report on gentle aberration-corrected scanning transmission electron microscopy investigations of eight (15)N-rich or D-rich organic grains within two carbonaceous Renazzo-type (CR) chondrites and two interplanetary dust particles (IDPs) originating from comets. Organic matter in the IDP samples is less aromatic than that in the CR chondrites, and its functional group chemistry is mainly characterized by C-O bonding and aliphatic C. Organic grains in CR chondrites are associated with carbonates and elemental Ca, which originate either from aqueous fluids or possibly an indigenous organic source. One distinct grain from the CR chondrite NWA 852 exhibits a rim structure only visible in chemical maps. The outer part is nanoglobular in shape, highly aromatic, and enriched in anomalous nitrogen. Functional group chemistry of the inner part is similar to spectra from IDP organic grains and less aromatic with nitrogen below the detection limit. The boundary between these two areas is very sharp. The direct association of both IDP-like organic matter with dominant C-O bonding environments and nanoglobular organics with dominant aromatic and C-N functionality within one unique grain provides for the first time to our knowledge strong evidence for organic synthesis in the early solar system activated by an anomalous nitrogen-containing parent body fluid. PMID:25288736

Vollmer, Christian; Kepaptsoglou, Demie; Leitner, Jan; Busemann, Henner; Spring, Nicole H; Ramasse, Quentin M; Hoppe, Peter; Nittler, Larry R

2014-10-28

12

SIPS: Solar Irradiance Prediction System Stefan Achleitner  

E-print Network

SIPS: Solar Irradiance Prediction System Stefan Achleitner Computer Science and Engineering the variability and dynamics are the largest. We propose SIPS, Solar Irradiance Prediction System, a novel sensing infrastructure using wireless sensor networks (WSNs) to enable sensing of solar irradiance for solar power

Cerpa, Alberto E.

13

SOLAR IRRADIANCE FORECASTING FOR THE MANAGEMENT OF SOLAR ENERGY SYSTEMS  

E-print Network

SOLAR IRRADIANCE FORECASTING FOR THE MANAGEMENT OF SOLAR ENERGY SYSTEMS Detlev Heinemann Oldenburg or progress with respect to the development of solar irradiance forecasting methods. Heck and Takle (1987 presents different state-of-the-art approaches to solar irradiance forecasting in different time scales

Heinemann, Detlev

14

Total solar irradiance trend during solar cycles 21 and 22  

Microsoft Academic Search

Results from Activity Cavity Radiometer Irradiance Monitor (ACRIM) experiments show an upward trend in total solar irradiance of 0.036 percent per decade between the minima of solar cycles 21 and 22. The trend follows the increasing solar activity of recent decades and, if sustained, could raise global temperatures. Trends of total solar irradiance near this rate have been implicated as

R. C. Willson

1997-01-01

15

Total Solar Irradiance Variability: A Review  

NASA Technical Reports Server (NTRS)

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

Pap, Judit M.

1996-01-01

16

Solar ultraviolet irradiance variations - A review  

Microsoft Academic Search

The absolute solar UV spectrum and the magnitude and structure of its temporal variations are examined. Solar magnetic activity and UV irradiance variations over the time scales of the evolution and rotation of solar active regions and over the 11-year solar cycle are studied and described. Data on EUV, Lyman-alpha, far UV, and middle UV irradiances are analyzed. Problems in

Judith Lean

1987-01-01

17

The SOLAR2000 empirical solar irradiance model and forecast tool  

Microsoft Academic Search

SOLAR2000 is a collaborative project for accurately characterizing solar irradiance variability across the spectrum. A new image- and full-disk proxy empirical solar irradiance model, SOLAR2000, is being developed that is valid in the spectral range of 1–1,000,000 nm for historical modeling and forecasting throughout the solar system. The overarching scientific goal behind SOLAR2000 is to understand how the Sun varies

W. Kent Tobiska; Tom Woods; Frank Eparvier; Rodney Viereck; Linton Floyd; Dave Bouwer; Gary Rottman; O. R. White

2000-01-01

18

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

19

Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

20

Solar Irradiance Variability and Climate  

E-print Network

The brightness of the Sun varies on all time scales on which it has been observed, and there is increasing evidence that it has an influence on climate. The amplitudes of such variations depend on the wavelength and possibly on the time scale. Although many aspects of this variability are well established, the exact magnitude of secular variations (going beyond a solar cycle) and the spectral dependence of variations are under discussion. The main drivers of solar variability are thought to be magnetic features at the solar surface. The climate reponse can be, on a global scale, largely accounted for by simple energetic considerations, but understanding the regional climate effects is more difficult. Promising mechanisms for such a driving have been identified, including through the influence of UV irradiance on the stratosphere and dynamical coupling to the surface. Here we provide an overview of the current state of our knowledge, as well as of the main open questions.

Solanki, S K; Haigh, J D

2013-01-01

21

Solar irradiance variations due to active regions  

Microsoft Academic Search

Questions regarding changes in solar irradiance due to activity are important, since such changes may have a significant effect on the earth's climate. Solar irradiance measurements conducted outside the earth's atmosphere and, therefore, not affected by it have become possible by utilizing for such measurements satellites, such as the Nimbus 7 and the Solar Maximum Mission satellite (ACRIM experiment). The

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

1982-01-01

22

The solar spectral irradiance since 1700  

Microsoft Academic Search

The change in the irradiance spectrum of the Sun from 1700 to the last solar minimum is determined and compared to the change in the spectrum between activity minimum and maximum. For this purpose we have used detailed model flux spectra of solar magnetic features. Also, time-series of the solar spectral irradiance since 1700 in different wavelength bands are reconstructed.

M. Fligge; S. K. Solanki

2000-01-01

23

Total Solar Irradiance Satellite Composites and their  

E-print Network

Chapter 12 Total Solar Irradiance Satellite Composites and their Phenomenological Effect on Climate Nicola Scafetta Active Cavity Radiometer Irradiance Monitor (ACRIM) Lab, Coronado, CA 92118, USA, Duke. Phenomenological solar signature on climate 310 9. Conclusion 312 1. INTRODUCTION A contiguoustotal solar

Scafetta, Nicola

24

The Solar EUV Irradiance: New Insights  

NASA Astrophysics Data System (ADS)

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

Eparvier, Francis

2012-07-01

25

Long-Term Solar Irradiance Variability  

NASA Technical Reports Server (NTRS)

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

Pap, J. M.

1996-01-01

26

Solar spectral irradiance 1200--2550 A at solar maximum  

Microsoft Academic Search

Full-disk solar solar spectral irradiances at solar maximum were obtained in the spectral range 1200--2550 A at a spectral resolution of approximately 1 A from rocket observations above White Sands, New Mexico, on June 5, 1979. Comparison with measurements made near solar minimum indicates approximately a factor of 2.5 increase in the irradiance at 1200 A, a 20% increase near

George H. Mount; Gary J. Rottman; J. Gethyn Timothy

1980-01-01

27

Correlations of solar cycle 22 UV irradiance  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

28

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

29

Thematic Mapper bandpass solar exoatmospheric irradiances  

Microsoft Academic Search

Based on solar irradiance data published by Neckel and Labs (1984) and Iqbal (1983), the solar exoatmospheric irradiances for Thematic Mapper (TM) bands 1, 2, 3 and 4 have been calculated. Results vary by up to 1 per cent from our previously published values which were based on earlier data of Neckel and Labs. For TM bands 5 and 7,

B. L. MARKHAM; J. L. BARKER

1987-01-01

30

The LASP Interactive Solar IRradiance Datacenter (LISIRD)  

Microsoft Academic Search

LASP has created an online resource for combined solar irradiance datasets from the SORCE, TIMED, UARS, and SME missions. The LASP Interactive Solar IRradiance Datacenter (LISIRD) not only provides unified access to the individual datasets, but also combines them for ease of use by scientists, educators, and the general public. In particular, LISIRD makes available composite spectra and time series.

M. Snow; T. N. Woods; F. G. Eparvier; J. Fontenla; J. Harder; W. E. McClintock; C. Pankratz; E. Richard; A. Windnagel; D. Woodraska

2005-01-01

31

Variations in total solar irradiance during solar cycle 22  

Microsoft Academic Search

In this study, we have attempted to model the variations in total solar irradiance from two spacecraft. Specifically, we have modeled the Earth Radiation Budget on the Nimbus 7 spacecraft and the active cavity radiometer irradiance monitor (ACRIM-I) on the Solar Maximum Mission (SMM) spacecraft using ground-based photometry of sunspots and faculae from the San Fernando Observatory (SFO). Additionally, for

G. A. Chapman; A. M. Cookson; J. J. Dobias

1996-01-01

32

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

33

Long-term changes in composition of solar particles implanted in extraterrestrial materials  

NASA Technical Reports Server (NTRS)

Analysis of lunar surface samples for elements implanted therein by solar corpuscular radiation reveals evidence for the following compositional changes over a time period between 1.5 and 3 Gyr: 50-percent decreases in the ratios He-4/Ar-36 and Xe/Ar-36; a 20-percent increase in the ratio He-3/He-4; a 3-percent increase in the ratio Ne-20/Ne-22; and a 50-percent increase in the ratio N-15/N-14. The causes of these changes are not resolved at this time but may include (1) a change in acceleration conditions of the solar wind, (2) a change in flux of solar energetic particles relative to that of the solar wind, and (3) a change in composition of the solar convective zone. There is good evidence for a long-term decrease in the solar-wind flux.

Kerridge, J. F.; Signer, P.; Wieler, R.; Becker, R. H.; Pepin, R. O.

1991-01-01

34

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

Microsoft Academic Search

The Laboratory for Atmospheric and Space Physics (LASP) has developed the LASP Interactive Solar IRradiance Datacenter (LISIRD) to provide access to a comprehensive set of solar irradiance measurements. LISIRD has recently been updated to serve many new datasets and models, including data from SORCE, UARS-SOLSTICE, SME, and TIMED-SEE, and model data from the Flare Irradiance Spectral Model (FISM). The user

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

2010-01-01

35

Downscaling of global solar irradiation in R  

E-print Network

A methodology for downscaling solar irradiation from satellite-derived databases is described using R software. Different packages such as raster, parallel, solaR, gstat, sp and rasterVis are considered in this study for improving solar resource estimation in areas with complex topography, in which downscaling is a very useful tool for reducing inherent deviations in satellite-derived irradiation databases, which lack of high global spatial resolution. A topographical analysis of horizon blocking and sky-view is developed with a digital elevation model to determine what fraction of hourly solar irradiation reaches the Earth's surface. Eventually, kriging with external drift is applied for a better estimation of solar irradiation throughout the region analyzed. This methodology has been implemented as an example within the region of La Rioja in northern Spain, and the mean absolute error found is a striking 25.5% lower than with the original database.

Antonanzas-Torres, F; Antonanzas, J; Perpiñán, O

2013-01-01

36

Sources of Solar Total Irradiance Variations  

NASA Astrophysics Data System (ADS)

The daily images and magnetograms acquired by MDI are a rich source of information about the contributions of different types of solar regions to variations in the total solar irradiance (TSI). These data have been used to determine the temporal variation of the MDI irradiance, the mean intensity of the solar disk in the continuum at 676.8 nm. The short-term (days to weeks) variations of the MDI irradiance and TSI are in excellent agreement with rms differences of 0.011%. This indicates that MDI irradiance is an excellent proxy for short-term variations of TSI from the competing irradiance contributions of regions causing irradiance increases, such as plages and bright network, and regions causing irradiance decreases, such as sunspots. However, the long-term or solar cycle variation of the MDI proxy and TSI differ over the 11-year period studied. The results indicate that the primary sources of the long-term (several months or more) variations in TSI are regions with magnetic fields between about 80 and 600 G. The results also suggest that the difference in the long-term variations of the MDI proxy and TSI is due to a component of TSI associated with sectors of the solar spectrum where the contrast in intensity between plages and the quiet Sun is enhanced ( e.g., the UV) compared to the MDI proxy. This is evidence that the long-term variation of TSI is due primarily to solar cycle variations of the irradiance from these portions of solar spectrum, a finding consistent with modeling calculations indicating that approximately 60% of the change in TSI between solar minimum and maximum is produced by the UV part of the spectrum shortward of 400 nm (Solanki and Krivova, Space Sci. Rev. 125, 53, 2006).

Withbroe, George L.

2009-06-01

37

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

38

The integration of terrestrial and extraterrestrial solar generators into existing power generation systems  

NASA Astrophysics Data System (ADS)

The effectiveness of a decentralized terrestrial solar-power generation system and a solar-power-satellite/microwave-transmission generation system is analyzed comparatively for the case of the Federal Republic of Germany (FRG). The models considered are a 5-GW-peak-capacity network comprising one million 50-sq-m roof arrays of Si solar cells and the 5-GW-capacity 52-sq-km-array 100-sq-km-receiver reference satellite system proposed by the DOE and NASA; both models are assumed to be integrated into the present FRG power network, and the load requirements and system outputs are compared in a series of graphs and diagrams. The terrestrial system is found to provide no savings in grid-capacity or plant-capacity requirements and minimal fuel savings (at least in the FRG climate) corresponding to at most 5 Pfennig/kWh. The satellite system, assuming that a European grid can provide an emergency reserve, offers substantial fuel and plant-capacity savings corresponding to about 8.75 Pfennig/kWh. It is pointed out that the overall economy of these systems depends on the investment costs of installing them (plus the investment cost of additional conventional plant capacity for the terrestrial model).

Stoy, B.; Beyer, U.

39

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.

40

Secular total solar irradiance trend during solar cycles 2123 Richard C. Willson  

E-print Network

Secular total solar irradiance trend during solar cycles 21­23 Richard C. Willson Center solar irradiance (TSI) observations can be combined in a precise solar magnetic cycle length composite, Astrophysics, and Astronomy: Solar irradiance; 7594 Solar Physics, Astrophysics, and Astronomy: Instruments

41

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

42

Spectral solar irradiance data sets for selected terrestrial conditions  

Microsoft Academic Search

Direct normal and global spectral solar irradance data sets are presented for selected terrestrial conditions, along with a brief review of previous data sets. The new data sets presented cover the 0.305 micron to 4.045 microns region and were generated with the rigorous BRITE Monte Carlo radiative transfer code, the revised Neckel and Labs extraterrestrial solar spectrum, the U.S. standard

R. Hulstrom; R. Brid; C. Riordan

1985-01-01

43

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

44

SPECTRAL SOLAR IRRADIANCE AND ITS ENTROPIC EFFECT ON EARTH'S CLIMATE  

E-print Network

SPECTRAL SOLAR IRRADIANCE AND ITS ENTROPIC EFFECT ON EARTH'S CLIMATE Wei Wu1 , Yangang Liu1 of the spectral solar irradiance (SSI) at the top of the Earth's atmosphere by the Solar Radiation and Climate the total solar irradiance (TSI) at the top of the Earth's atmosphere (TOA) varies little (only about 0

45

LISIRD: Where to go for Solar Irradiance Data  

Microsoft Academic Search

LASP, the Laboratory for Atmospheric and Space Physics, has been providing web access to solar irradiance measurements, reference spectra, composites and model data covering the solar spectrum from .1 to 2400 nm through LISIRD, the LASP Interactive Solar IRradiance Datacenter. No single instrument can measure the solar spectral irradiance from X-rays to the IR, but the ensemble of LASP instruments

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

2008-01-01

46

Extraterrestrial hydrogeology  

Microsoft Academic Search

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

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

2005-01-01

47

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

2006-01-16

48

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

49

Total solar irradiance during the Holocene F. Steinhilber,1  

E-print Network

Total solar irradiance during the Holocene F. Steinhilber,1 J. Beer,1 and C. Fro¨hlich2 Received 20 solar irradiance covering 9300 years is presented, which covers almost the entire Holocene. This reconstruction is based on a recently observationally derived relationship between total solar irradiance

Wehrli, Bernhard

50

RETHINKING SATELLITE BASED SOLAR IRRADIANCE MODELLING R. W. Mueller  

E-print Network

RETHINKING SATELLITE BASED SOLAR IRRADIANCE MODELLING R. W. Mueller , K.F. Dagestad ¡ , R-German Aerospace Center; 5-Ecole des Mines de Paris ABSTRACT Accurate solar irradiance data are not only Heliosat-3 a new type of solar irradiance scheme is developed. This new type will be based on radiative

Heinemann, Detlev

51

How the inclination of Earth's orbit affects incoming solar irradiance  

E-print Network

How the inclination of Earth's orbit affects incoming solar irradiance L. E. A. Vieira,1 A. Norton of the evolution of climate. Accurate measurements of total solar irradiance (TSI) variability by instruments to millennia time-scales. Additionally, long- term changes in Earth's orbit modulate the solar irradiance

52

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

53

Climatic change due to solar irradiance changes  

Microsoft Academic Search

Solar irradiance reconstructions back to 1874 are used to estimate the effect of the Sun on global-mean temperature. The importance of the history effect of the Sun on global-mean temperature. The importance of the history effect, whereby recent temperature changes may be influenced significantly by past forcing changes, is evaluated. Modelled temperature changes are shown to be relatively insensitive to

T. M. L. Wigley; S. C. B. Raper

1990-01-01

54

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

Microsoft Academic Search

The Laboratory for Atmospheric and Space Physics (LASP) is enhancing the LASP Interactive Solar IRradiance Datacenter (LISIRD) to provide access to a comprehensive set of solar spectral irradiance measurements. LISIRD has recently been updated to serve many new datasets and models, including sunspot index, photometric sunspot index, Lyman-alpha, and magnesium-II core-to-wing ratio. A new user interface emphasizes web-based interactive visualizations,

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

2009-01-01

55

Irradiation chemistry in the outer solar system  

NASA Astrophysics Data System (ADS)

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

Brown, Michael E.

2014-11-01

56

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

57

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases for  

E-print Network

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases explores the possibilities provided by satellite-based surface solar irradiation databases synthesis of 17 satellite-based surface solar irradiation databases available so far is presented through

Paris-Sud XI, Université de

58

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases for  

E-print Network

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases explores the possibilities provided by satellite-based surface solar irradiation databases. Selection and/or peer-review under responsibility of ISES Keywords: surface solar irradiation; satellite

Recanati, Catherine

59

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

E-print Network

COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA with spacecraft measurements of total solar irradiance (TSI) variations for 8 yr beginning with the declining. Daily averages of total solar irradiance (TSI) observations from several spacecraft radiometers over

60

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

E-print Network

COMPARISON OF TOTAL SOLAR IRRADIANCE WITH NASA/NATIONAL SOLAR OBSERVATORY SPECTROMAGNETOGRAPH DATA with spacecraft measurements of total solar irradiance (TSI) variations for 8 yr beginning with the declining in terrestrial climate. Daily averages of total solar irradiance (TSI) observations from several spacecraft

61

Behavior of lithium in irradiated solar cells.  

NASA Technical Reports Server (NTRS)

The current state of the art in radiation resistant lithium-doped silicon solar cells is reviewed. Fabrication techniques are reviewed. Characteristics of lithium-doped cells are discussed. Behavior of lithium-doped cells during 1 MeV electron irradiation are studied for various types of cells. Effects of variations in lithium and oxygen concentration are shown and discussed. Capacitance measurements at various voltages, frequencies and temperatures are used to detect charges in lithium donor concentration and the formation of defects during irradiation. Physical models to explain the observed effects are presented.

Carter, J. R., Jr.; Downing, R. G.

1971-01-01

62

Extraterrestrial Water  

Microsoft Academic Search

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

J. F. Kasting

2002-01-01

63

Lower Limit on Solar Irradiance Variation  

NASA Astrophysics Data System (ADS)

Helioseismic data reveal that the historical Sun cannot be any dimmer than it is now at activity minimum. Changes in the frequencies of solar oscillations are the most precise probe of irradiance variations over the solar cycle. Using MDI data, Dziembowski and Goode (2005) showed that f-mode changes arise from the direct effect of the evolving magnetic activity, while p-mode changes are due to small, activity induced changes in convective flows very near to the solar surface (turbulent pressure). The f-modes also sharply limit the allowed field growth with activity, and the limit is consistent with the observations of Lin and Rimmele (1999). Combining MDI data with BBSO Ca II K, we find the Sun is smooth at activity minimum and becomes increasingly corrugated with rising activity. The overall physical picture is one in which the Sun is hottest and smoothest at activity minimum, and becomes cooler, more corrugated and irradiant with rising activity. Thus, these results place a lower limit on irradiance variations, consistent with current activity minima, and are roughly consistent with a picture of Spruit (2000) and the behavior of faculae as reported by Berger et al. (2005).

Goode, P. R.

2005-12-01

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

Periodicities of solar irradiance and solar activity indices, I  

Microsoft Academic Search

Using a standard FFT time series analysis, our results show an 8–11 months periodicity in the solar total and UV irradiances, 10.7 cm radio flux, Ca-K plage index, and sunspot blocking function. The physical origin of this period is not known, but the evidence in the results exclude the possibility that the observed period is a harmonic due to the

Judit Pap; W. Kent Tobiska; S. David Bouwer

1990-01-01

66

Recurrence plots of sunspots, solar flux and irradiance  

Microsoft Academic Search

The paper shows the recurrence and cross recurrence plots of three time series, concerning data of the solar activity. The data are the sunspot number and the values of solar radio flux at 10.7 cm and of solar total irradiance, which are known as highly correlated. To compare the series, the radio flux and irradiance values are monthly averaged. Recurrence

Amelia Sparavigna

2008-01-01

67

A discussion of plausible solar irradiance variations, 1700-1992  

Microsoft Academic Search

From satellite observations the solar total irradiance is known to vary. Sunspot blocking, facular emission, and network emission are three identified causes for the variations. In this paper we examine several different solar indices measured over the past century that are potential proxy measures for the Sun's irradiance. These indices are (1) the equatorial solar rotation rate, (2) the sunspot

Douglas V. Hoyt; Kenneth H. Schatten

1993-01-01

68

The variability of the solar ultraviolet spectral irradiances  

NASA Technical Reports Server (NTRS)

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

Timothy, J. G.

1979-01-01

69

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

70

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.

2014-07-01

71

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

72

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

73

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

74

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

75

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

76

Variation of solar irradiance and mode frequencies during Maunder minimum  

E-print Network

Using the sunspot numbers reported during the Maunder minimum and the empirical relations between the mode frequencies and solar activity indices, the variations in the total solar irradiance and 10.7 cm radio flux for the period 1645 to 1715 is estimated. We find that the total solar irradiance and radio flux during the Maunder minimum decreased by 0.19% and 52% respectively, as compared to the values for solar cycle 22.

A. Bhatnagar; Kiran Jain; S. C. Tripathy

2002-01-03

77

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

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) is enhancing the LASP Interactive Solar IRradiance Datacenter (LISIRD) to provide access to a comprehensive set of solar spectral irradiance measurements. LISIRD has recently been updated to serve many new datasets and models, including sunspot index, photometric sunspot index, Lyman-alpha, and magnesium-II core-to-wing ratio. A new user interface emphasizes web-based interactive visualizations, allowing users to explore and compare this data before downloading it for analysis. The data provided covers a wavelength range from soft X-ray (XUV) at 0.1 nm up to the near infrared (NIR) at 2400 nm, as well as wavelength-independent Total Solar Irradiance (TSI). Combined data from the SORCE, TIMED-SEE, UARS-SOLSTICE, and SME instruments provide almost continuous coverage from 1981 to the present, while Hydrogen Lyman-alpha (121.6 nm) measurements / models date from 1947 to the present. This poster provides an overview of the LISIRD system, summarizes the data sets currently available, describes future plans and capabilities, and provides details on how to access solar irradiance data through LISIRD interfaces at http://lasp.colorado.edu/lisird/.

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

2009-12-01

78

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

79

SURVEILLANCE OF PHOTOVOLTAIC SOLAR ENERGY SYSTEMS USING METEOSAT DERIVED IRRADIANCES  

E-print Network

SURVEILLANCE OF PHOTOVOLTAIC SOLAR ENERGY SYSTEMS USING METEOSAT DERIVED IRRADIANCES Annette Hammer of a year offering 90 % of the annual solar irradiation. 1 INTRODUCTION Photovoltaic (PV) Systems generate. These checks are done by calculating the estimated output of the PV system with a simulation-model. The model

Heinemann, Detlev

80

Long-term downward trend in total solar irradiance  

Microsoft Academic Search

The first 5 years (from 1980 to 1985) of total solar irradiance observations by the first Active Cavity Radiometer Irradiance Monitor (ACRIM I) experiment on board the Solar Maximum Mission spacecraft show a clearly defined downward trends of -0.019% per year. The existence of this trend has been confirmed by the internal self-calibrations of ACRIM I, by independent measurements from

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

1986-01-01

81

Fuzzy algorithm for estimation of solar irradiation from sunshine duration  

Microsoft Academic Search

Solar irradiation and sunshine duration are intimately related phenomena and a model involving the relationship between them can best be derived by methods that explicitly take vagueness into account. In this paper, the theory of fuzzy sets, especially fuzzy modeling, is employed to represent solar irradiation and sunshine duration relations as a set of fuzzy rules. A fuzzy logic algorithm

Zekai ?en

1998-01-01

82

Application of Singular Spectrum Analysis to Solar Irradiance Variability  

NASA Technical Reports Server (NTRS)

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

Pap, Judit M.; Varadi, Ferenc

1995-01-01

83

Solar Cells, 18 (1986) 213-222 SOLAR IRRADIANCE CONVERSION MODELS*  

E-print Network

r, ~ Solar Cells, 18 (1986) 213-222 #12;213 SOLAR IRRADIANCE CONVERSION MODELS* RICHARD PEREZ estimating, on an hourly basis, the irradiance received by a sloping surface in a given location, depending or transposition models that use available direct and horizontal global or diffuse hourly irradiance records

Perez, Richard R.

84

Reconstruction of solar irradiance using the Group sunspot number  

E-print Network

We present a reconstruction of total solar irradiance since 1610 to the present based on variations of the surface distribution of the solar magnetic field. The latter is calculated from the historical record of the Group sunspot number using a simple but consistent physical model. Our model successfully reproduces three independent data sets: total solar irradiance measurements available since 1978, total photospheric magnetic flux from 1974 and the open magnetic flux since 1868 (as empirically reconstructed from the geomagnetic aa-index). The model predicts an increase in the total solar irradiance since the Maunder Minimum of about 1.3 \\rm{Wm$^{-2}$}.

L. Balmaceda; N. A. Krivova; S. K. Solanki

2007-03-07

85

The demography of extraterrestrial civilizations  

NASA Technical Reports Server (NTRS)

Studies carried out within the last ten years on the nature and distribution of extraterrestrial intelligent life are reviewed. Arguments for the absence of intelligent life in the Galaxy based on the assumption that at least some of these would have engaged in colonization and for the presence of colonies of extraterrestrials in some undiscovered location in the solar system are presented, and it is noted that both these views rest on the notion that interstellar travel can be achieved at high velocities in very large vehicles, which has been questioned. Alternative suggestions concerning interstellar exploration by automated probes and the possible extended time scale and motivation for galactic colonization are pointed out. Attention is then given to arguments for the extreme smallness of one of the factors in the Drake equation used to estimate the number of communicative extraterrestrial civilizations in the Galaxy, including the frequency of single stars, the likelihood that planets with the correct initial composition and conditions for life are at the proper distance from their stars, the probability of the formation of DNA and the origin of life, and the time for the evolution of intelligence. It is concluded that it seems likely that other civilizations exist in the Galaxy, although the number and distribution of such civilizations may only be determined by the detection of one or more examples.

Billingham, J.

1981-01-01

86

Creation of a composite solar ultraviolet irradiance data set  

Microsoft Academic Search

Characterization of long-term solar ultraviolet (UV) irradiance variations is important for understanding the radiative forcing of Earth's atmosphere. Extending such a characterization to multidecadal timescales requires the merging of multiple satellite data sets. Currently available irradiance data sets show both absolute offsets and time-dependent differences that vary between spectral ranges. We have created a composite spectral UV irradiance data set

Matthew T. DeLand; Richard P. Cebula

2008-01-01

87

A survey of the polar cap density based on Cluster EFW probe measurements: Solar wind and solar irradiation dependence  

E-print Network

a survey of the polar cap densities and the response to changes in the solar irradiation, solar wind on Cluster EFW probe measurements: Solar wind and solar irradiation dependence, J. Geophys. Res., 117, A01216 is strongly influenced by solar activity, in particular irradiance in the extreme ultraviolet range (EUV

Bergen, Universitetet i

88

STATUS OF HIGH RESOLUTION SOLAR IRRADIANCE MAPPING FROM SATELLITE DATA  

E-print Network

STATUS OF HIGH RESOLUTION SOLAR IRRADIANCE MAPPING FROM SATELLITE DATA Richard Perez & Marek Vignola Solar Energy Laboratory University of Oregon Eugene, OR 97403 fev@darkwing.uoregon.edu Pierre presents examples of high resolution solar radiation maps generated from satellite data using the semi

Perez, Richard R.

89

Validation of the UARS solar ultraviolet irradiances: Comparison with the ATLAS 1 and 2 measurements  

Microsoft Academic Search

The measurements of the solar ultraviolet spectral irradiance made by the two Upper Atmosphere Research Satellite (UARS) solar instruments, Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and SOLar STellar Irradiance Comparison Experiment (SOLSTICE), are compared with same-day measurements by two solar instruments on the shuttle ATmospheric Laboratory for Applications and Science (ATLAS) missions, ATLAS SUSIM and Shuttle Solar Backscatter Ultra Violet

T. N. Woods; D. K. Prinz; G. J. Rottman; P. C. Crane; R. P. Cebula; E. Hilsenrath; G. E. Brueckner; M. D. Andrews; O. R. White; M. E. VanHoosier; L. E. Floyd; L. C. Herring; B. G. Knapp; C. K. Pankratz; P. A. Reiser

1996-01-01

90

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

91

A presentation of solar irradiation data suitable for solar energy application  

Microsoft Academic Search

Temporal global solar radiation patterns are discussed for two climatically U.S. stations (Phoenix, Arizona and Geneseo, New York). A concept of the solar utilization season is developed along with methodology to assess the frequency of periods of consecutive days when solar irradiation values do not attain specified threshold values. This analysis is considered more appropriate in applications of solar energy

R. L. Lougeay; A. J. Brazel

1984-01-01

92

Guide to solar reference spectra and irradiance models  

NASA Astrophysics Data System (ADS)

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

Tobiska, W. Kent

93

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

SAS Honors Seminar 256: Extraterrestrial Life 9/27/2011 #12; Reading for Thursday (9/29) Bennett & Shostak 3.3, 3.5, 4.6 ­ background on solar system Stevenson (2001) ­ background on Jupiter's moons Canup & Ward (2002) ­ proposed model for formation of Jupiter's moons ­ read only abstract, §1

Baker, Andrew J.

94

7. The Search for Extraterrestrial Life  

Microsoft Academic Search

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

Ulmschneider Peter

2003-01-01

95

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

96

Curation of Extraterrestrial Samples  

NASA Astrophysics Data System (ADS)

NASA's current collection of extraterrestrial materials includes the Apollo lunar samples, meteorites collected in Antarctica, cosmic dust, and space-exposed hardware. During the current decade, samples are expected to be returned by spacecraft from the solar wind, a comet, and an asteroid. Future sample return missions to Mars and diverse other bodies have been planned or recommended. Curation, an integral part of any sample return mission, comprises preparation and allocation of samples for research and education, initial characterization of new samples, and secure storage for the benefit of future generations. Solar Wind: The Genesis spacecraft, launched in 2001, is scheduled to return a collection of solar wind atoms and ions to Earth in 2004. Upon return, the spacecraft will be brought to a dedicated cleanroom where the solar wind collectors will be subdivided and distributed to researchers. Comet: The Stardust spacecraft, launched in 1999, will sample interplanetary dust as well as solid particles from the coma of Comet Wild 2 before returning to Earth in 2006. The spacecraft will be brought to a dedicated laboratory where particles will be extracted from the collectors and distributed. Asteroid: The Japanese Space Agency is building a spacecraft to sample the surface material of asteroid 1998 SF36. The MUSES-C mission is scheduled to be launched late in 2002 and return to Earth in 2007. Following initial processing in Japanese laboratories, a subset of the sample will be curated and distributed to international researchers. Future Sample Return Missions: One or more robotic Mars sample return missions are currently being planned. Planetary protection requirements will likely dictate construction of a Receiving Laboratory for assessment of possible life and biohazard in the samples, as well as a separate laboratory for long-term curation. Missions have also been planned or recommended that would return samples from the surface of Venus, the far side of the Moon, the atmosphere and satellites of Mars, a near-Earth asteroid, and a comet nucleus. Curation of such samples will require laboratories dedicated to the specific characteristics of the body and the spacecraft. Concepts and technologies important to future sample curation are currently being tested in a new generation of laboratories.

Allen, C.

97

COMBINING SOLAR IRRADIANCE MEASUREMENTS AND VARIOUS SATELLITE-DERIVED PRODUCTS TO  

E-print Network

COMBINING SOLAR IRRADIANCE MEASUREMENTS AND VARIOUS SATELLITE-DERIVED PRODUCTS TO A SITE power plants depend strongly on the availability of beam irradiance. Direct solar irradiance is highly fusion, direct normal or beam irradiance, Plataforma Solar de Almería -PSA, concentrating solar power

Heinemann, Detlev

98

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

99

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

100

Solar Spectral Irradiance variations: the long-term view  

NASA Astrophysics Data System (ADS)

Solar Spectral Irradiance variations: the long-term view S.K. Solanki Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany The total and spectral irradiance of the Sun are prime candidates for external forcing of the Earth's climate system. Whereas variations of total solar irradiance have been observed and modelled with great success, our corresponding knowledge of the variation of spectral irradi-ance is, by comparison, still in its infancy. Although, on short time-scales multiple measured time series and models are now available, on longer time-scales models are the only source of information. Until recently even the models were rather restricted, being either based purely on proxies, or limited in spectral range. A new generation of models is now available, which goes beyond the limitations of the earlier approaches. An overview of the models and their results is given, with the emphasis being placed on the most recent ones.

Solanki, Sami K.

101

On the variation of the Nimbus 7 total solar irradiance  

NASA Technical Reports Server (NTRS)

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

Wilson, Robert M.

1992-01-01

102

Spectral solar irradiance before and during a Harmattan dust spell  

Microsoft Academic Search

Measurements of the ground-level spectral distributions of the direct, diffuse and global solar irradiance between 300 and 1100 nm were made at Akure (7.15°N, 5.5°E), Nigeria, in December 1991 before and during a Harmattan dust spell employing a spectroradiometer (LICOR LI-1800) with 6 nm resolution. The direct spectral solar irradiance which was initially reduced before the dust storm was further

Z. Debo Adeyefa; Björn Holmgren

1996-01-01

103

Climatology of Solar Irradiance on Inclined Surfaces 4: Parts 1, 2 and 3.  

National Technical Information Service (NTIS)

The following variables were measured (March 1979 to October 1981): global solar radiance, various directions (Eppley pyranometer); direct solar irradiance on surface perpendicular to sunbeam (Eppley pyrheliometer); ground reflected solar irradiance (Eppl...

J. K. M. Verdonschot, G. J. van den Brink, W. H. Slob

1984-01-01

104

A reconstruction of total solar irradiance since 1700  

Microsoft Academic Search

The irradiance of the Sun is reconstructed from 1700 to the present, whereby the contributions of active regions and the quiet Sun are modelled separately. A method is proposed which allows the contribution of active-region faculae and sunspots to irradiance changes to be isolated even when only a single proxy of solar activity, such as sunspot relative number, RZ is

S. K. Solanki; M. Fligge

1999-01-01

105

Measurements of solar total irradiance and its variability  

Microsoft Academic Search

The development of electrically self calibrated cavity pyrheliometric instrumentation that occurred in the early 20th century provided the technological base for experiments to detect variability of the solar total irradiance. Experiments from ground based observatories, aircraft and balloons during the 1st half of the 20th century were unable to achieve sufficient accuracy or long term precision to unambiguously detect irradiance

Richard C. Willson

1984-01-01

106

Standard Solar Spectra: Air Mass 1.5  

NSDL National Science Digital Library

This site presents information about American Society for Testing and Materials (ASTM) Standard Extraterrestrial Spectrum Reference E-490-00. Information is available in two tables, one listing the Solar Constant in alternative units, and the other listing solar irradiance at the planets. There are also links to related resources.

Renewable Resource Data Center (RReDC); Laboratory, National R.

107

Comparison of Solar UV Spectral Irradiance from SUSIM and SORCE  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

108

Ground-Based Correlates of Solar Irradiance Variation  

NASA Technical Reports Server (NTRS)

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

Jones, Harrison P.

2001-01-01

109

A technique for determining solar irradiance deficits. [photovoltaic arrays design  

NASA Technical Reports Server (NTRS)

An analytic technique which determines the variation of solar irradiance from long term averages is presented. The technique involves computer-assisted data reduction techniques, and was designed to improve system reliability by determining the amount of storage capability required to supplement a baseline system. Variations in time intervals of up to 60 days can be determined, and 10 years of data collection are reviewed. The technique involves first calculating average monthly irradiance values, then examining the average irradiance deviation over time intervals. The calculation procedure is clarified by determining solar energy level probabilities and the long term solar energy deviation (achieved by repeatedly integrating actual irradiance figures). It is found that a 15% increase in collector area and the addition of energy storage or backup are essential contributions to achieving cost-effectiveness. In addition, one to seven no-sun day storage capacities are required to accommodate weather caused deficits.

Gonzalez, C. C.; Ross, R. G., Jr.

1982-01-01

110

Recurrence plots of sunspots, solar flux and irradiance  

E-print Network

The paper shows the recurrence and cross recurrence plots of three time series, concerning data of the solar activity. The data are the sunspot number and the values of solar radio flux at 10.7 cm and of solar total irradiance, which are known as highly correlated. To compare the series, the radio flux and irradiance values are monthly averaged. Recurrence plots display the oscillating behaviour with remarkable features. Moreover, cross recurrence plots help in identifying time lags between the sunspot number maximum and the maximum of radio or irradiance signals, in circumstances where the data values are highly dispersed. Image processing is useful too, in enhancing the monitoring. An interesting behaviour is displayed by cross recurrence plots of irradiance, which are not symmetric with respect to the line of identity.

Sparavigna, Amelia

2008-01-01

111

An assessment of the solar irradiance record for climate studies  

NASA Astrophysics Data System (ADS)

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

Kopp, Greg

2014-04-01

112

Historical Studies on Extraterrestrial Materials  

NASA Astrophysics Data System (ADS)

The measurement of radioactive nuclides is one of the primary methods for dating extraterrestrial and terrestrial materials and processes. We have developed techniques to measure cosmogenic nuclides with half-lives in the range from the 1 x 105 year Ca-41 to the 1.57 x 107 year I-129. Our goal is to use these measurements to help us understand the fundamental processes affecting the evolutionary history of extraterrestrial materials, such as lunar and meteoritic samples, including lunar meteorites and Martian meteorites. In addition to the histories of meteorites and lunar surface materials themselves we study the past activities of the Sun (solar cosmic rays, SCR) and galactic cosmic rays. We also use these cosmogenic nuclides to study cosmic spherules (micrometeorites), polar ice, and terrestrial surface rocks. The advent of Accelerator Mass Spectrometry (AMS) dramatically increased the measurement sensitivity and accuracy of long lived nuclides. The detection limits are a few times 105 atoms for Be-10 , Al-26, and Cl-16 with ratios of 10-14 - 10-15 to stable isotopes.

1997-01-01

113

Climate sensitivity of the Earth to solar irradiance David H. Douglass  

E-print Network

Climate sensitivity of the Earth to solar irradiance David H. Douglass Department of Physics. A weaker effect, which must exist, is solar irradiance. We have determined the solar effect on the temperature from satellites measurements (available since 1979) of the solar irradiance and the temperature

Douglass, David H.

114

Short-term solar irradiance and irradiation forecasts via different time series techniques: A preliminary study  

E-print Network

This communication is devoted to solar irradiance and irradiation short-term forecasts, which are useful for electricity production. Several different time series approaches are employed. Our results and the corresponding numerical simulations show that techniques which do not need a large amount of historical data behave better than those which need them, especially when those data are quite noisy.

Join, Cédric; Fliess, Michel; Muselli, Marc; Nivet, Marie Laure; Paoli, Christophe; Chaxel, Frédéric

2014-01-01

115

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

116

Total Solar Irradiance Data Available for Studying Trends  

NASA Astrophysics Data System (ADS)

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

Morris, K. L.

2005-12-01

117

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

Microsoft Academic Search

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

Luis Martín; Luis F. Zarzalejo; Jesús Polo; Ana Navarro; Ruth Marchante; Marco Cony

2010-01-01

118

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

119

A new generation of satellite based solar irradiance calculation schemes R. W. Mueller, D. Heinemann, C. Hoyer & R. Kuhlemann  

E-print Network

A new generation of satellite based solar irradiance calculation schemes R. W. Mueller, D. Piernavieja Instituto Tecnologico de Canarias, Spain Keywords: radiative transfer, solar irradiance, MSG irradiance calculation scheme, including the functional treatment of the diurnal variation of the solar

Heinemann, Detlev

120

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

121

Correlation of Spectral Solar Irradiance with solar activity as measured by VIRGO  

E-print Network

Context. The variability of Solar Spectral Irradiance over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the SIM experiment on SORCE has published an unexpected negative correlation with Total Solar Irradiance of the visible spectral range. It is compensated by a strong and positive variability of the near UV range. Aims. We aim to verify whether the anti-correlated SIM/SORCE-trend in the visible can be confirmed by independent observations of the VIRGO experiment on SOHO. The challenge of all space experiments measuring solar irradiance are sensitivity changes of their sensors due to exposure to intense UV radiation, which are difficult to assess in orbit. Methods. We analyze a 10-year time series of VIRGO sun photometer data between 2002 and 2012. The variability of Spectral Solar Irradiance is correlated with the variability of the Total Solar Irradiance, which is...

Wehrli, C; Shapiro, A I

2013-01-01

122

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

Microsoft Academic Search

Surface UV irradiances were measured at two different sites in Greece during June 1996 under noncloudy conditions. The measured UV irradiances are simulated by a radiative transfer model using measured ozone density and aerosol optical depth profiles. The absolute difference between model and measurements ranges between -5% and +5% with little dependence on wavelength. The temporal and solar zenith angle

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

1998-01-01

123

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

124

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

125

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

126

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

127

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

128

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). Within this paper, the new type of the solar irradiance calculation scheme, including the functional treatment of the diurnal variation of the solar irradiance, is described. 1 INTRODUCTION Remote Sensing from

Paris-Sud XI, Université de

129

Solar Physics (2005) 230: 129139 C Springer 2005 THE TOTAL IRRADIANCE MONITOR (TIM): SCIENCE RESULTS  

E-print Network

Solar Physics (2005) 230: 129­139 C Springer 2005 THE TOTAL IRRADIANCE MONITOR (TIM): SCIENCE observations from the Total Irradiance Monitor (TIM) are discussed since the SOlar Radiation and Climate noise level. The total solar irradiance (TSI) from the TIM is about 1361 W/m2, or 4­5 W/m2 lower than

130

Estimation of 5-min solar global irradiation on tilted planes by ANN method in Bouzareah, Algeria  

E-print Network

Estimation of 5-min solar global irradiation on tilted planes by ANN method in Bouzareah, Algeria K irradiation data of Bouzareah (Algeria). The ANN is developed and optimized on the basis of two years of solar is around 8% for the nRMSE. Keywords- Solar irradiation; Artificial Neural Network; Estimation I

Paris-Sud XI, Université de

131

The TSI Radiometer Facility -absolute calibrations for total solar irradiance instruments  

E-print Network

The TSI Radiometer Facility - absolute calibrations for total solar irradiance instruments Greg, CO 80303 ABSTRACT The total solar irradiance (TSI) climate data record includes overlapping to calibrate a TSI instrument end-to-end for irradiance at solar power levels to these needed accuracy levels

132

Total Solar Irradiance Calibration Transfer Experiment/TIM Frequently Asked Questions  

E-print Network

TCTE Total Solar Irradiance Calibration Transfer Experiment/TIM Frequently Asked Questions What is the purpose of the TCTE mission? The Total Solar Irradiance Calibration Transfer Experiment (TCTE to monitor changes in solar irradiance at the top of the Earth's atmosphere. TCTE will launch as one of five

Mojzsis, Stephen J.

133

Was UV spectral solar irradiance lower during the recent low sunspot minimum?  

E-print Network

Was UV spectral solar irradiance lower during the recent low sunspot minimum? Mike Lockwood1 analysis is presented of solar UV spectral irradiance for the period between May 2003 and August 2005, when data are available from both the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) instrument (on

Lockwood, Mike

134

Data-Driven Model for Solar Irradiation Based on Satellite Observations  

E-print Network

Data-Driven Model for Solar Irradiation Based on Satellite Observations Ilias Bilionisa , Emil M a data-driven model for solar irradiation based on satellite ob- servations. The model yields Preprint ANL/MCS-P5141-0514 1. Introduction Solar irradiation is the amount of power per square meter

Anitescu, Mihai

135

Ecological Modelling 143 (2001) 227243 A globally applicable model of daily solar irradiance  

E-print Network

Ecological Modelling 143 (2001) 227­243 A globally applicable model of daily solar irradiance at many ground stations, the total daily solar irradiance (Rs) received at the earth's surface to measured solar irradiance. In a global comparison for the year 1987, VP-RAD-estimated and satellite

Hunt Jr., E. Raymond

136

Models of Solar Irradiance Variability and the Instrumental Temperature Record  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

137

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

E-print Network

trapped than released, leading to global warming and climate change. Depletion of atmospheric ozone by the ABC? Such studies should lead to an improved understanding of global warming and climate change;3.1 Chemical Compositions and Global Warming Global warming is directly related to solar irradiance. The earth

Nahar, Sultana Nurun

138

SORCE and Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

139

Uncertainty of measurements of spectral solar UV irradiance  

Microsoft Academic Search

Most investigations on the nature and effects of solar ultraviolet (UV) radiation at the Earth's surface require measurements of high accuracy combined with well-defined procedures to assess their quality. Here we present a general evaluation of all relevant errors and uncertainties associated with measurements of spectral global irradiance in the UV. The uncertainties are quantified in terms of dependence of

G. Bernhard; G. Seckmeyer

1999-01-01

140

Spectral Irradiance Curve Calculations for Any Type of Solar Eclipse.  

National Technical Information Service (NTIS)

A simple procedure is described for calculating the eclipse function (EF), alpha, and hence the spectral irradiance curve (SIC), (1-alpha), for any type of solar eclipse: namely, the occultation (partial/total) eclipse and the transit (partial/annular) ec...

A. Deepak, J. E. Merrill

1974-01-01

141

Reconstructing the Solar VUV Irradiance over the Past 60 Years  

NASA Technical Reports Server (NTRS)

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

Chamberlin, Phillip

2010-01-01

142

Solar UV irradiation and dermal photoaging  

Microsoft Academic Search

The skin is increasingly exposed to ambient UV-irradiation thus increasing risks for photooxidative damage with long-term detrimental effects like photoaging, characterized by wrinkles, loss of skin tone and resilience. Photoaged skin displays alterations in the cellular component and extracellular matrix with accumulation of disorganized elastin and its microfibrillar component fibrillin in the deep dermis and a severe loss of interstitial

Meinhard Wlaschek; Iliana Tantcheva-Poór; Lale Naderi; Wenjian Ma; Lars Alexander Schneider; Ziba Razi-Wolf; Jutta Schüller; Karin Scharffetter-Kochanek

2001-01-01

143

Optimisation of buildings' solar irradiation availability  

Microsoft Academic Search

In order to improve the sustainability of new and existing urban settlements it is desirable to maximise the utilisation of the solar energy incident on the building envelope, whether by passive or active means. To this end we have coupled a multi-objective optimisation algorithm with the backwards ray tracing program RADIANCE which itself uses a cumulative sky model for the

Jerome Henri Kaempf; Marylene Montavon; Josep Bunyesc; Darren Robinson; Raffaele Bolliger

2010-01-01

144

Solar Spectral Irradiance under Clear and Cloudy Skies: Measurements and a Semiempirical Model  

Microsoft Academic Search

In a combined effort, the Centre for Solar Energy and Hydrogen Research in Germany and the Solar Energy Research Institute in the United States analyzed several thousand measurements of the solar spectral irradiance recorded at four sites. The goal was to develop a semiempirical model that describes the total solar spectral irradiance for clear and cloudy sky conditions based on

Stefan Nann; Carol Riordan

1991-01-01

145

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

146

Solar total irradiance in cycle 23  

E-print Network

The apparently unusual behaviour of the TSI during the most recent minimum of solar activity 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. We use sensitive, 60-minute 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 twice-monthly. The computed TSI is then compared to the PMOD composite of TSI measurements and to 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. 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...

Krivova, N A; Schmutz, W

2011-01-01

147

Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

148

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

149

Recent solar extreme ultraviolet irradiance observations and modeling: A review  

NASA Astrophysics Data System (ADS)

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

1993-11-01

150

Evaluating Ground-based Proxies for Solar Irradiance Variation  

NASA Technical Reports Server (NTRS)

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

Oegerle, William (Technical Monitor); Jordan, Stuart

2003-01-01

151

Design and calibration of the solar irradiance monitor  

NASA Astrophysics Data System (ADS)

The solar irradiance monitor (SIM), with the design accuracy of 5%, used to monitor the secular changes of the total solar irradiance on FY-3 satellite, takes the sun-scanning measurement method on-orbit. Compared to the sun-tracking measurement method, this method simplifies the structure and cuts the cost, but the measuring accuracy is affected by the sun-synchronous orbit, sunlight incidence angle and the installing angle of the SIM in the satellite. Through the ground calibration experiment, studies on the affection of different sunlight incidence angles to the measurement accuracy. First, by the satellite tool kit (STK) simulation software, simulates the orbital parameters of the sun-synchronous satellite, and calculates the Sun ascension and declination at any time. By the orbit coordinate transformation matrix gets the components of the Sun vectors to the axes of the satellite, and base on the components designs the field of view and the installing angles of the SIM. Then, designs and completes the calibration experiment to calibrate the affection of the incidence angles. Selecting 11 different angles between the sunlight and the satellite X-axis, measures the total solar irradiance by the SIM at each angle, and compares to the irradiances of the SIAR reference radiometers, and gets the coefficient curves of the three channels of the SIM. Finally, by the quadratic fitting, gets the correction equations on the incidence angles: 5 2 3 R1 5.71x10-5?2 - 2.453 10-5 ?2 1.0302, R2 = 2.84×10-5?2-1.965x10-3?+1.0314 and R3 =1.72x10-5?2-4.184x10-4?+0.9946. The equations will improve the on-orbit measurement accuracy of the solar irradiance, and are very important to the on-orbit data processing after the satellite launched.

Yang, Dong-jun; Fang, Wei; Ye, Xin; Wang, Yu-peng; Gong, Cheng-hu; Zhang, Guang-wei

2011-08-01

152

Measurement of the absolute solar UV irradiance and variability  

NASA Technical Reports Server (NTRS)

Radiation in the wavelength interval 150-350 nm initiates chemical reactions in the lower mesosphere and the stratosphere through the photodissociation of ambient molecular species. This experiment measures the total solar irradiance, above the Earth's atmosphere, in this wavelength interval, using three spectrometers. Measurements are made from rockets on a once-a-year basis and are used with satellite observations to determine both the absolute irradiance and the long term variability of the sun in the UV. A fourth spectrometer is being added to the payload to measure the emission in the hydrogen Lyman-alpha emission at 121.67 nm.

Mentall, James E.

1990-01-01

153

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

154

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

155

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

National Technical Information Service (NTIS)

Accurate understanding of global solar variability is of clear astrophysical interest and is also vital to distinguish natural from anthropogenic causes of long-term changes in terrestrial climate. Daily averages of total solar irradiance (TSI) observatio...

H. P. Jones, D. D. Branston, P. B. Jones, M. D. Popescu

2003-01-01

156

27Solar Irradiance Changes and the Sunspot Cycle Irradiance (also called insolation) is a measure of the amount of sunlight power  

E-print Network

27Solar Irradiance Changes and the Sunspot Cycle Irradiance (also called insolation) is a measure the solar irradiance and sunspot number since January 1979 according to NOAA's National Geophysical Data climate. The solar irradiance data obtained by the ACRIM satellite, measures the total number of watts

157

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

158

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

159

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

160

Secular total solar irradiance trend during solar cycles 21-23  

Microsoft Academic Search

A series of satellite total solar irradiance (TSI) observations can be combined in a precise solar magnetic cycle length composite TSI database by determining the relationship between two non-overlapping components: ACRIM1 and ACRIM2. [Willson and Hudson, 1991; Willson, 1994] An ACRIM composite TSI time series using the Nimbus7\\/ERB results [Hoyt et al., 1992] to relate ACRIM1 and ACRIM2 demonstrates a

Richard C. Willson; Alexander V. Mordvinov

2003-01-01

161

PUBLISHED ONLINE: 15 AUGUST 2010 | DOI: 10.1038/NPHYS1741 The effect of flares on total solar irradiance  

E-print Network

solar irradiance Matthieu Kretzschmar1 *, Thierry Dudok de Wit1 , Werner Schmutz2 , Sabri Mekaoui3 from relatively moderate solar flares in total solar irradiance data. We find that the total energy identified up to now7 in the total solar irradiance (TSI), that is, the flux of solar light received at all

Loss, Daniel

162

Do flares count for the variations of total solar irradiance?  

Microsoft Academic Search

Observations made with radiometers on board of space missions offer us the total solar irradiance (TSI) data since 1978 (from ERB\\/Nimbus to VIRGO\\/SOHO). This 25-year interval made possible the reveal of the 11-year cycle variability in the data series, with a difference in amplitude of about 0.15% from minimum to maximum. A major part of this variation is explained as

Adrian Oncica; Miruna Daniela Popescu; Marilena Mierla; Georgeta Maris

2002-01-01

163

Microquasar Jet Irradiation of the Proto-Solar Nebula?  

E-print Network

We explore the possibility that a now-extinct microquasar may have irradiated the proto-solar neighborhood, causing the 'anomalously' high local 11B/10B isotopic ratio. Given the population and typical lifetimes of radio-emitting X-ray binaries, we find the probability of such an event having occurred is not unreasonable. We comment on some tests of the scenario that could be carried out by observing the elemental abundances in the vicinity of microquasars, in particular SS433.

Yousaf Butt; Nikos Prantzos

2006-02-09

164

Correlation of spectral solar irradiance with solar activity as measured by VIRGO  

NASA Astrophysics Data System (ADS)

Context. The variability of solar spectral irradiance (SSI) over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the Spectral Irradiance Monitor (SIM) experiment on the Solar Radiation and Climate Experiment (SORCE) has published an unexpected negative correlation with total solar irradiance (TSI) of the visible spectral range. It is compensated by a strong and positive variability of the near UV range. Aims: We aim to verify whether the anti-correlated SIM-trend in the visible can be confirmed by independent observations of the Variability of solar IRadiance and Gravity Oscillations (VIRGO) experiment on the SOlar and Heliospheric Observatory (SOHO) satellite. The challenge of all space experiments measuring solar irradiance are sensitivity changes of their sensors due to exposure to intense UV radiation, which are difficult to assess in orbit. Methods: We exclude the first six years prior to 2002 where one or more fast processes contributed to instrumental changes and analyse a ten-year timeseries of VIRGO sun photometer data between 2002 and 2012. The variability of SSI is correlated with the variability of the TSI, which is taken as a proxy for solar activity. Results: Observational evidence indicates that after six years only one single long-term process governs the degradation of the backup sun photometer in VIRGO which is operated once a month. This degradation can be well approximated by a linear function over ten years. The analysis of the residuals from the linear trend yield robust positive correlations of spectral irradiance at 862, 500, and 402 nm with total irradiance. In the analysis of annual averages of these data the positive correlations change into weak negative correlations, but with little statistical significance for the 862 nm and 402 nm data. At 500 nm the annual spectral data are still positively correlated with TSI. The persisting positive correlation at 500 nm is in contradiction to the SIM results. Appendix A is available in electronic form at http://www.aanda.org

Wehrli, C.; Schmutz, W.; Shapiro, A. I.

2013-08-01

165

Estimating Solar Irradiance on Inclined Surfaces: A Review and Assessment of Methodologies  

Microsoft Academic Search

A variety of numerical models for calculating the solar irradiance for an inclined surface are described and evaluated using data for Vancouver, B.C., Canada. While all the hourly models have a common approach for calculating the direct component of the solar irradiance there is a variety of methods for calculating the diffuse irradiance based on the portion of the sky

JOHN E. HAY; DONALD C. McKAY

1985-01-01

166

Satellite Observations of Solar Irradiance and Sun-Climate Impacts  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

167

Satellite Observations of Solar Irradiance and Sun-Climate Impacts  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

168

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

169

Variation of collector efficiency and receiver thermal loss as a function of solar irradiance  

NASA Astrophysics Data System (ADS)

Efficiency and thermal loss of a parabolic trough concentrating solar collector have been measured for values of solar irradiance between 400 W/sq m and 100 W/sq m. Both parameters are shown to vary significantly with changing solar irradiance. Significant errors can result from improper use of currently published efficiency data.

Dudley, V. E.; Workhoven, R. M.

170

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

Microsoft Academic Search

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

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

2006-01-01

171

Rethinking satellite-based solar irradiance modelling The SOLIS clear-sky module  

Microsoft Academic Search

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

R. W. Muellera; K. F. Dagestadb; P. Ineichenc; M. Schroedter-Homscheidtd; S. Crose; D. Dumortierf; R. Kuhlemanng; J. A. Olsethb; G. Piernaviejah; C. Reisei; L. Walde; D. Heinemanng

172

The total solar irradiance, UV emission and magnetic flux during the last solar cycle minimum  

E-print Network

We have analyzed the total solar irradiance (TSI) and the spectral solar irradiance as ultraviolet emission (UV) in the wavelength range 115-180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (The Solar Radiation and Climate Experiment) during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the mid-latitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long- lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots) a coherent structure has been found, in which the phase between th...

Benevolenskaya, E E

2013-01-01

173

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

174

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

175

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

Microsoft Academic Search

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

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

2002-01-01

176

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

177

Which solar EUV indices are best for reconstructing the solar EUV irradiance ?  

E-print Network

The solar EUV irradiance is of key importance for space weather. Most of the time, however, surrogate quantities such as EUV indices have to be used by lack of continuous and spectrally resolved measurements of the irradiance. The ability of such proxies to reproduce the irradiance from different solar atmospheric layers is usually investigated by comparing patterns of temporal correlations. We consider instead a statistical approach. The TIMED/SEE experiment, which has been continuously operating since Feb. 2002, allows for the first time to compare in a statistical manner the EUV spectral irradiance to five EUV proxies: the sunspot number, the f10.7, Ca K, and Mg II indices, and the He I equivalent width. Using multivariate statistical methods such as multidimensional scaling, we represent in a single graph the measure of relatedness between these indices and various strong spectral lines. The ability of each index to reproduce the EUV irradiance is discussed; it is shown why so few lines can be effectively reconstructed from them. All indices exhibit comparable performance, apart from the sunspot number, which is the least appropriate. No single index can satisfactorily describe both the level of variability on time scales beyond 27 days, and relative changes of irradiance on shorter time scales.

T. Dudok de Wit; M. Kretzschmar; J. Aboudarham; P. -O. Amblard; F. Auchere; J. Lilensten

2007-02-02

178

Climate-regime cospectrum analysis: shortwave solar irradiance with other meteorological parameters for regionally spaced locales.  

E-print Network

??Solar irradiance has both short-term (less than 12 hour) and long-term (intra-seasonal) variations. Understanding these fluctuations is crucial for improving solar resource forecasting and evaluating… (more)

Rayl, Jeffrey

2012-01-01

179

Maintenance of a long term total solar irradiance data series  

NASA Technical Reports Server (NTRS)

The dispersion of the measurements that contributed to the previously defined space absolute radiometric reference (SARR) is investigated by objective statistical analysis. The estimated standard deviation with which the reference is known is 0.22 W/sq m, corresponding to 0.016 percent of its mean value. Several updates are made in the SARR referenced total solar irradiance data series, which was previously obtained from November 1978 until December 1993. The shift in 1898-1990 of the NIMBUS 7 instrument identified by Lee in 1995 is investigated and taken into account, resulting in new values for the NIMBUS 7 measurements before 1990 and in a new SARR adjustment coefficient for the active cavity radiometer irradiance monitoring (ACRIM) 1 instrument. The data series is extended to the present by adding level 1 data of DIARAD/VIRGO on board SOHO. A preliminary SARR coefficient for level 1 DIARAD/VIRGO was obtained by comparison with SARR referenced ACRIM 2 data.

Dewitte, S.; Crommelynck, D.; Joukoff, A.

1997-01-01

180

An investigation on the relationship between solar irradiance signal from ERBS and 8B solar neutrino flux signals from SNO  

NASA Astrophysics Data System (ADS)

In the present work an attempt has been made to investigate statistical association between solar neutrino flux data (both D2O and Salt data) collected from Sudbury Neutrino Observatory and solar irradiance data detected by Earth Radiation Budget Satellite. To serve the present purpose we have used the Multifractal Detrended Cross Correlation Analysis (MF-DCCA) based on Detrended Fluctuation Analysis (MF-X-DFA) method and the Detrending Moving Average Analysis (MF-X-DMA) which explores the long term power-law cross correlations between above two pairs of data sets. Investigation also has been made to find the frequency and time dependent local phase relationship in each pair of data sets using continuous wavelet transform (CWT) based Semblance Analysis. The Semblance Analysis reveals that there exists positive phase correlation as well as negative phase correlation between solar irradiance and D2O data at different time sub-intervals. This type of mixed phase correlation is also experienced between solar irradiance and Salt data at different time sub-intervals. The causal relationship between the D2O and the solar irradiance time series and that between Salt and solar irradiance time series have been revealed using Singular Spectral Analysis (SSA). Calculations indicate that possibly the present solar neutrino flux data (both D2O and Salt data) is supportive to predict the solar irradiance data but may not the vice versa which in turn suggests that the variability of nuclear energy generation process inside the Sun may influence the solar activity.

Khondekar, Mofazzal H.; Ghosh, Dipendra N.; Ghosh, Koushik; Bhattacharya, Anup Kumar

2012-12-01

181

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

182

Skin cancer, irradiation, and sunspots: the solar cycle effect.  

PubMed

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

Valachovic, Edward; Zurbenko, Igor

2014-01-01

183

Influence of Extraterrestrial Radiation on Radiation Portal Monitors  

SciTech Connect

Cosmic radiation and solar flares can be a major source of background radiation at the Earth’s surface. This paper examines the relationship between extraterrestrial radiation and the detectable background in radiation portal monitors used for homeland security applications. Background radiation data from 13 radiation portal monitor facilities are examined and compared against external sources of data related to extraterrestrial radiation, including measurements at neutron monitors located at 53 cosmic-ray observatories around the Earth, four polar orbiting satellites, three geostationary satellites, ground-based geomagnetic field data from observatories around the Earth, a solar magnetic index, solar radio flux data, and sunspot activity data. Four-years (January 2003 through December 2006) of data are used in this study, which include the latter part of Solar Cycle 23 as solar activity was on the decline. The analysis shows a significant relationship between some extraterrestrial radiation and the background detected in the radiation portal monitors. A demonstrable decline is shown in the average gamma ray and neutron background at the radiation portal monitors as solar activity declined over the period of the study.

Keller, Paul E.; Kouzes, Richard T.

2009-06-01

184

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

185

Modelling total solar irradiance since 1878 from simulated magnetograms  

E-print Network

We present a new model of total solar irradiance (TSI) based on magnetograms simulated with a surface flux transport model (SFTM) and the SATIRE (Spectral And Total Irradiance REconstructions) model. Our model provides daily maps of the distribution of the photospheric field and the TSI starting from 1878. 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 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. To model the ephemeral region cycles, we assume that their length and amplitude are related to that of the sunspot 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 magn...

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

2014-01-01

186

TRENDS IN DIRECT NORMAL SOLAR IRRADIANCE IN OREGON FROM 1979-2003 Laura Riihimaki  

E-print Network

TRENDS IN DIRECT NORMAL SOLAR IRRADIANCE IN OREGON FROM 1979-2003 Laura Riihimaki Frank Vignola To better understand the characteristics of the region's solar resource, a preliminary study was undertaken of trends in direct normal irradiance from three sites around Oregon over a period of 25 years. An overall

Oregon, University of

187

American Solar Energy Society Proc. ASES Annual Conference, Raleigh, NC, 2011 SHORT-TERM IRRADIANCE VARIABILITY  

E-print Network

be estimated from hourly satellite-derived irradiances data such as Solar Anywhere [9] or the NSRDB [10© American Solar Energy Society ­ Proc. ASES Annual Conference, Raleigh, NC, 2011 SHORT-TERM IRRADIANCE VARIABILITY -- STATION PAIR CORRELATION AS A FUNCTION OF DISTANCE Richard Perez ASRC, 251 Fuller

Perez, Richard R.

188

Validation of 1985-1997 Active Cavity Radiometer Spacecraft Measurements of Total Solar Irradiance Variability  

NASA Technical Reports Server (NTRS)

Since 1978, long-term variations in the total solar irradiance (solar constant) have been monitored using spacecraft radiometers, at the 0.01% precision level. The irradiance measurements were performed from the Earth Radiation Budget Satellite [ERBS], Nimbus-7, Solar Maximum Mission [SMM], Upper Atmosphere Research Satellite [UARS], European Retrievable Carrier (EURECA), Solar and Heliospheric Observatory [SOHO], and the Space Shuttle Atmospheric Laboratory for Applications and Science [ATLAS] spacecraft platforms. Radiometer responses can drift or shift at precision levels of a few hundreds of a percent. In-flight calibration sources are not available to detect radiometer response changes at radiometric accuracy or precision levels near the 0.01% (0.1 W/sq m) level. Inconsistent trends among the sets were used to identify possible instrumental drifts or shifts which may be incorrectly interpreted as solar irradiance changes while consistent trends among the different measurement sets were used to detect long-term irradiance variability components. In this paper, 1991-1998 corresponding ERBS, UARS, SOHO, and ATLAS irradiance measurements are inter-compared with each other as well as with the ERBS empirical irradiance fit. The empirical irradiance fit is based upon 10.7-cm solar radio flux (F10) and photometric sunspot index (PSI), indices of solar magnetic activity. Analyses of recent data sets identified no long-term shifts and drifts in the ERBS, SOHO, or UARS data sets. The typical value of the total solar irradiance is approximately 1365 Watts per meter squared (W/sq m).

Lee, Robert B., III; Wilson, Robert S.

1998-01-01

189

Variations of Total Solar Irradiance Produced by Structural Changes of the Solar Interior  

NASA Astrophysics Data System (ADS)

In recent years, a lively controversy has existed regarding the sources contributing to variations of the total solar irradiance (TSI) on time scales of the magnetic activity cycle or longer. On one side are those who claim that the TSI variations can be explained entirely as a consequence of surface magnetic features (sunspots, faculae, and magnetic network). On the other side, a number of researchers claim that variations of the solar luminosity emerging from the solar interior, as a consequence of structural readjustments caused by the changing internal (dynamo) magnetic field, are important; and that indeed, they may dominate on those longer time scales. The case for the first viewpoint has been recently made in Eos; the case for the second viewpoint is presented in this article. The case for the surface origin is based on two premises:(1) Surface activity dominates the TSI variability on hours to months time scales. The passage of an active region on the solar disk can be clearly seen reflected on the measured TSI. (2) The semi-analytical calculations by Spruit [1982, 1994], which concluded that structural readjustments in the solar interior could not occur on time scales shorter than the thermal time scale for the base of the solar convection zone, approximately 100,000 years.

Sofia, Sabatino

2004-06-01

190

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

191

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

192

Extraterrestrial Nucleobases in Carbonaceous Chondrites  

NASA Astrophysics Data System (ADS)

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

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

193

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

194

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

195

Hegel, Analogy, and Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

Georg Wilhelm Friedrich Hegel rejected the possibility of life outside of the Earth, according to several scholars of extraterrestrial life. Their position is that the solar system and specifically the planet Earth is the unique place in the cosmos where life, intelligence, and rationality can be. The present study offers a very different interpretation of Hegel's statements about the place of life on Earth by suggesting that, although Hegel did not believe that there were other solar systems where rationality is present, he did in fact suggest that planets in general, not the Earth exclusively, have life and possibly also intelligent inhabitants. Analogical syllogisms are superficial, according to Hegel, insofar as they try to conclude that there is life on the Moon even though there is no evidence of water or air on that body. Similar analogical arguments for life on the Sun made by Johann Elert Bode and William Herschel were considered by Hegel to be equally superficial. Analogical arguments were also used by astronomers and philosophers to suggest that life could be found on other planets in our solar system. Hegel offers no critique of analogical arguments for life on other planets, and in fact Hegel believed that life would be found on other planets. Planets, after all, have meteorological processes and therefore are "living" according to his philosophical account, unlike the Moon, Sun, and comets. Whereas William Herschel was already finding great similarities between the Sun and the stars and had extended these similarities to the property of having planets or being themselves inhabitable worlds, Hegel rejected this analogy. The Sun and stars have some properties in common, but for Hegel one cannot conclude from these similarities to the necessity that stars have planets. Hegel's arguments against the presence of life in the solar system were not directed against other planets, but rather against the Sun and Moon, both of which he said have a different nature from Earth and planets. Although he did not explicitly discuss the possibility of life on comets, the fourth type of body in his theory of the solar system, it is clear that he rejected the views of Bode and Johann Heinrich Lambert, who did defend this possibility. Again, Hegel's critique of the use of analogical argument is important here. The Sun, comets, and moons are not analogous to the Earth or to the planets; these are four different bodies with different forms of motion and different physical constitutions. Only planets have completeness according to Hegel because only they have water, air, earth, and light, and completeness in this sense is necessary for life. Hegel discerned a need to make distinctions in nature rather than to consider superficially different realities as fundamentally similar. Celestial bodies should not be considered, according to Hegel, as all of one type or nature, as one kind.

Ross, Joseph T.

196

Prebiotic significance of extraterrestrial ice photochemistry: detection of hydantoin in organic residues.  

PubMed

The delivery of extraterrestrial organic materials to primitive Earth from meteorites or micrometeorites has long been postulated to be one of the origins of the prebiotic molecules involved in the subsequent apparition of life. Here, we report on experiments in which vacuum UV photo-irradiation of interstellar/circumstellar ice analogues containing H(2)O, CH(3)OH, and NH(3) led to the production of several molecules of prebiotic interest. These were recovered at room temperature in the semi-refractory, water-soluble residues after evaporation of the ice. In particular, we detected small quantities of hydantoin (2,4-imidazolidinedione), a species suspected to play an important role in the formation of poly- and oligopeptides. In addition, hydantoin is known to form under extraterrestrial, abiotic conditions, since it has been detected, along with various other derivatives, in the soluble part of organic matter of primitive carbonaceous meteorites. This result, together with other related experiments reported recently, points to the potential importance of the photochemistry of interstellar "dirty" ices in the formation of organics in Solar System materials. Such molecules could then have been delivered to the surface of primitive Earth, as well as other telluric (exo-) planets, to help trigger first prebiotic reactions with the capacity to lead to some form of primitive biomolecular activity. PMID:22059641

de Marcellus, Pierre; Bertrand, Marylène; Nuevo, Michel; Westall, Frances; Le Sergeant d'Hendecourt, Louis

2011-11-01

197

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

198

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

) ­ television (Star Trek) Bohannon (2008) ­ video game (Spore) #12; Proposed/approved term paper topics Athar and Their Impact on Extraterrestrial Life Reichert ­ The History of SETI Sbeiti ­ Extraterrestrial Life in Popular

Baker, Andrew J.

199

Extraterrestrial civilizations: Problems of their evolution  

NASA Technical Reports Server (NTRS)

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

Leskov, L. V.

1987-01-01

200

Submitted for Publication to SOLAR ENERGY PRODUCING SATELLITE-DERIVED IRRADIANCES IN COMPLEX ARID TERRAIN  

E-print Network

Submitted for Publication to SOLAR ENERGY PRODUCING SATELLITE-DERIVED IRRADIANCES IN COMPLEX ARID describes a methodology to correct satellite-derived irradiances over complex terrain for models that use recently proposed a new semi-empirical model for deriving global and direct irradiances from the visible

Perez, Richard R.

201

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

Microsoft Academic Search

An empirical model of variations in the total solar irradiance caused by observed changes in photospheric magnetic activity between 1874 and 1988 is presented. The model provides a remarkably good representation of the irradiance variations observed by satellite-borne radiometers between 1980 and 1988. It suggests that the mean total irradiance has been rising steadily since about 1945, with the largest

P. Foukal; J. Lean

1990-01-01

202

Significant reduction of surface solar irradiance induced by aerosols in a suburban region in northeastern China  

E-print Network

Significant reduction of surface solar irradiance induced by aerosols in a suburban region-induced changes in downwelling shortwave surface irradiances are analyzed in this paper. It is shown that the mean irradiance per unit of AOD is 404.5 W mÃ?2 . About 63.8% of this reduction is offset by an increase in diffuse

Li, Zhanqing

203

Sediment-dispersed extraterrestrial chromite traces a major asteroid disruption event.  

PubMed

Abundant extraterrestrial chromite grains from decomposed meteorites occur in middle Ordovician (480 million years ago) marine limestone over an area of approximately 250,000 square kilometers in southern Sweden. The chromite anomaly gives support for an increase of two orders of magnitude in the influx of meteorites to Earth during the mid-Ordovician, as previously indicated by fossil meteorites. Extraterrestrial chromite grains in mid-Ordovician limestone can be used to constrain in detail the temporal variations in flux of extraterrestrial matter after one of the largest asteroid disruption events in the asteroid belt in late solar-system history. PMID:12738859

Schmitz, Birger; Häggström, Therese; Tassinari, Mario

2003-05-01

204

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

205

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

Microsoft Academic Search

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

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

2010-01-01

206

Solar spectral irradiance, 120 to 190nm, October 13, 1981January 3, 1982  

Microsoft Academic Search

Beginning on October 13, 1981 a two channel spectrometer aboard the Solar Mesosphere Explorer has been obtaining daily measurements of full disc solar irradiance. These observations cover the spectral interval 120 to 305nm with approx..75nm spectral resolution. The relative accuracy of the measurements from day to day over the first three solar rotations is approximately 1%. In this report we

G. J. Rottman; C. A. Barth; R. J. Thomas; G. H. Mount; G. M. Lawrence; D. W. Rusch; R. W. Sanders; G. E. Thomas

1982-01-01

207

Proton Irradiation Environment of Solar System Objects in the Heliospheric Boundary Regions  

E-print Network

Proton Irradiation Environment of Solar System Objects in the Heliospheric Boundary Regions John F, Laboratory for Solar and Space Physics, Code 612.4, NASA Goddard Space Flight Center, Greenbelt, MD 20771 of outer solar system objects, Scattered Disk Objects and comets, include many known members

Richardson, John

208

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

209

NEW SOLAR EXTREME-ULTRAVIOLET IRRADIANCE OBSERVATIONS DURING FLARES  

SciTech Connect

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

Woods, Thomas N.; Hock, Rachel; Eparvier, Frank; Jones, Andrew R. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Chamberlin, Phillip C.; Klimchuk, James A. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Greenbelt, MD 20771 (United States); Didkovsky, Leonid; Judge, Darrell [Space Sciences Center, University of Southern California, Los Angeles, CA 90089 (United States); Mariska, John; Warren, Harry [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Schrijver, Carolus J. [Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304 (United States); Webb, David F. [Institute for Scientific Research, Boston College, Chestnut Hill, MA 02467 (United States); Bailey, Scott [Electrical and Computer Engineering Department, Virginia Tech, Blacksburg, VA 24061 (United States); Tobiska, W. Kent, E-mail: tom.woods@lasp.colorado.edu [Space Environment Technologies, Pacific Palisades, CA 90272 (United States)

2011-10-01

210

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

211

Apparent absorption of solar spectral irradiance in heterogeneous ice clouds  

NASA Astrophysics Data System (ADS)

Coordinated flight legs of two aircraft above and below extended ice clouds played an important role in the Tropical Composition, Cloud and Climate Coupling Experiment (Costa Rica, 2007). The Solar Spectral Flux Radiometer measured up- and downward irradiance on the high-altitude (ER-2) and the low-altitude (DC-8) aircraft, which allowed deriving apparent absorption on a point-by-point basis along the flight track. Apparent absorption is the vertical divergence of irradiance, calculated from the difference of net flux at the top and bottom of a cloud. While this is the only practical method of deriving absorption from aircraft radiation measurements, it differs from true absorption when horizontal flux divergence is nonzero. Differences between true and apparent absorption are inevitable in any inhomogeneous atmosphere, especially clouds. We show, for the first time, the spectral shape of measured apparent absorption and compare with results from a three-dimensional radiative transfer model. The model cloud field is created from optical thickness and effective radius retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator and from reflectivity profiles from the Cloud Radar System, both on board the ER-2. Although the spectral shape is reproduced by the model calculations, the measured apparent absorption in the visible spectral range is higher than the model results along extended parts of the flight leg. This is possibly due to a net loss of photons into neighboring cirrus-free areas that are not contained within the model domain.

Schmidt, K. Sebastian; Pilewskie, Peter; Mayer, Bernhard; Wendisch, Manfred; Kindel, Bruce; Platnick, Steven; King, Michael D.; Wind, Gala; Arnold, G. Tom; Tian, Lin; Heymsfield, Gerald; Kalesse, Heike

2010-05-01

212

Benchmarking of different approaches to forecast solar irradiance Elke Lorenz1, Wolfgang Traunmller2, Gerald Steinmaurer2, Christian Kurz3,  

E-print Network

Benchmarking of different approaches to forecast solar irradiance Elke Lorenz1, Wolfgang "Solar Resource Knowledge Management" to asses the accuracy of irradiance forecasts. Different approaches and operation strategies. Due to the strong increase of solar power generation the prediction of solar yields

Heinemann, Detlev

213

Duties to Extraterrestrial Microscopic Organisms  

NASA Astrophysics Data System (ADS)

Formulating a normative axiology for the treatment of extraterrestrial microscopic organisms, should they ever be found, requires an extension of environmental ethics to beyond the Earth. Using an ethical framework for the treatment of terrestrial micro-organisms, this paper elaborates a similar ethic for the treatment of extraterrestrial microscopic organisms. An ethic of `teloempathy' allows for the moral considerability of any organism that has `interests', based on rudimentary qualities of conativism, and therefore allows for an identical treatment of all life, related or not related to life on Earth. Although, according to this ethic, individual extraterrestrial microscopic organisms have a good of their own and even `rights', at this level the ethic can only be theoretical, allowing for the inevitable destruction of many individual organisms during the course of human exploratory missions, similarly to the daily destruction of microbes by humans on Earth. A holistic teloempathy, an operative ethic, not only provides a framework for human exploration, but it also has important implications for planetary protection and proposals to implement planetary-scale atmospheric alterations on other bodies. Even prior to the discovery of extraterrestrial life, or the discovery of a complete absence of such life, this exercise yields important insights into the moral philosophy that guides our treatment of terrestrial micro-organisms.

Cockell, C. S.

214

ExtraTerrestrial Radio Transmissions  

Microsoft Academic Search

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

Leland I. Anderson

1961-01-01

215

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

NASA Astrophysics Data System (ADS)

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

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

216

Some Effects of the Yellowstone Fire Smoke Cloud on Incident Solar Irradiance.  

NASA Astrophysics Data System (ADS)

The influence of the 1988 Yellowstone National Park fire, smoke cloud on incident broadband and spectral solar irradiance was studied using measurements made at the Solar Energy Research Institute's Solar Radiation Research Laboratory, Golden, Colorado.Results indicate that the smoke cloud's optical depth (at 500 nm) on a smoke-affected day was a factor of 6.3 times greater than on a clear day. The daily total global-horizontal irradiance on the smoky day was 91 percent of that on the clear day. The daily total direct-normal irradiance on the smoky day was 63 percent of that on the clear day. The daily total diffuse sky irradiance on the smoky day was 340 percent of that on the clear day. Analysis of spectral solar irradiance data shows a much more severe attenuation of the shorter wave-lengths (UV-visible) than the infrared region.

Hulstrom, Roland L.; Stoffel, Thomas L.

1990-12-01

217

Local enhanced solar irradiance on the ground generated by cirrus: measurements and interpretation  

NASA Astrophysics Data System (ADS)

This study concerns the influence of thin cirrus on the solar irradiance budget on the ground, using data obtained by remote sensing from a set of instruments operated at the Observatoire de Haute Provence (France). Comparisons between solar irradiance ground-based measurements obtained during clear and cloudy days usually show a lower irradiance in the latter case as expected. However, there are cases lasting a maximum of 30 min for which the solar irradiance is greater in the presence of cumulus than in clear-sky conditions, and this phenomenon was named enhanced solar irradiance. Our pyranometer measurements reveal the same phenomenon associated with the presence of thin clouds alone, as revealed by a daytime wide-field camera and occurring both in total and UVB* (280 to 320 nm) solar irradiance. In the case of thin cirrus, this phenomenon can last up to several hours. To understand this phenomenon, we have developed a model of solar light scattering within thin cirrus clouds that takes into account the presence of the atmosphere. The model reproduces the enhanced solar irradiance phenomenon in total and UBV* spectral range. Monoscattering and multiscattering processes inside the cirrus clouds also will be discussed.

Thuillier, Gérard; Perrin, Jean-Marie; Keckhut, Philippe; Huppert, François

2013-01-01

218

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

219

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

220

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

221

The role of extraterrestrial phenomena in extinction.  

PubMed

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. PMID:11542144

Raup, D M

1988-01-01

222

Ethics and extraterrestrial life  

Microsoft Academic Search

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

Charles Cockell

223

ISS SOLAR Spectrometers: Solar Spectral Irradiance Variability and its 2008 Minimum  

NASA Astrophysics Data System (ADS)

Onboard the SOLAR payload of the International Space Station (ISS), the SOLSPEC and SolACES spectrometers measure the solar spectral irradiance (SSI) from 16 to 2900 nm. The status of their operations will be presented. In 2008, a SSI minimum occurred. Data from the SOLSPEC and SolACES spectrometers have been merged to generate a spectrum extending from 16 to 2900 nm. We shall present its properties and comparison with other instruments running at the same time. As SSI reconstructions play an important role in climate modeling to provide SSI at different epochs, we have reconstructed this spectrum using available proxies. The accuracy of these reconstructions will be also discussed. The ISS orientation generally does not permit to permanently point the Sun. Periods of no Sun visibility varies from 14 days to a few days per month, season dependent, which consequently does not allow the measurements of the effects of the active regions during a complete solar rotation. In December 2012 a continuous period of measurements has been achieved. We shall present these measurements. For this period, a comparison between all available SSI in absolute unit will be shown as well as reconstructions using solar proxies by several models.

Thuillier, Gérard

2014-05-01

224

Comparing Sunspot Area and Sunspot Number as Proxies for Long-term Solar Irradiance Variation  

NASA Technical Reports Server (NTRS)

Because relevant observations from space began only in 1979 with Nimbus-7, it is impossible to correlate direct measurements of small changes in solar irradiance with terrestrial temperature over a number of solar cycles. Yet there is recent evidence that some feature of solar change over a cycle may have a larger influence on climate than would result from merely introducing the additional amount of heat delivered to Earth's atmosphere at solar minimum. It would be useful to check this possibility over several solar cycles. To do this, we would need a sufficiently reliable proxy for irradiance change that at least survives a test against the space observations. Sunspot area is a fairly straightforward parameter to measure, and is associated with the extent of magnetic activity known to correlate strongly with solar irradiance change. We have tested the use of sunspot area as a long-term proxy for solar irradiance change, using observations made at the Coimbra Solar Observatory, from which we obtain both statistically weighted sunspot numbers and sunspot areas over the period 1980-1992. These are both correlated with solar irradiance values measured from Nimbus-7 spacecraft over the same time period, to see if sunspot area offers affords a strong positive correlation and also a distinct advantage over sunspot number as a useful proxy that can then be compared with terrestrial temperature records. Preliminary results yield a positive correlation of 0.71 for sunspot area, but further tests are being conducted and will be reported.

Jordan, Stuart D.; Garcia, A. G.; Oegerle, William (Technical Monitor)

2002-01-01

225

Interpretation of Solar Irradiance Monitor measurements through analysis of 3D MHD simulations  

E-print Network

Measurements from the Solar Irradiance Monitor (SIM) onboard the SORCE mission indicate that solar spectral irradiance at Visible and IR wavelengths varies in counter phase with the solar activity cycle. The sign of these variations is not reproduced by most of the irradiance reconstruction techniques based on variations of surface magnetism employed so far, and it is not clear yet whether SIM calibration procedures need to be improved, or if instead new physical mechanisms must be invoked to explain such variations. We employ three-dimensional magneto hydrodynamic simulations of the solar photosphere to investigate the dependence of solar radiance in SIM Visible and IR spectral ranges on variations of the filling factor of surface magnetic fields. We find that the contribution of magnetic features to solar radiance is strongly dependent on the location on the disk of the features, being negative close to disk center and positive toward the limb. If features are homogeneously distributed over a region around ...

Criscuoli, Serena

2014-01-01

226

Reconstruction of daily solar UV irradiation from 1893 to 2002 in Potsdam, Germany.  

PubMed

Long-term records of solar UV radiation reaching the Earth's surface are scarce. Radiative transfer calculations and statistical models are two options used to reconstruct decadal changes in solar UV radiation from long-term records of measured atmospheric parameters that contain information on the effect of clouds, atmospheric aerosols and ground albedo on UV radiation. Based on earlier studies, where the long-term variation of daily solar UV irradiation was derived from measured global and diffuse irradiation as well as atmospheric ozone by a non-linear regression method [Feister et al. (2002) Photochem Photobiol 76:281-293], we present another approach for the reconstruction of time series of solar UV radiation. An artificial neural network (ANN) was trained with measurements of solar UV irradiation taken at the Meteorological Observatory in Potsdam, Germany, as well as measured parameters with long-term records such as global and diffuse radiation, sunshine duration, horizontal visibility and column ozone. This study is focussed on the reconstruction of daily broad-band UV-B (280-315 nm), UV-A (315-400 nm) and erythemal UV irradiation (ER). Due to the rapid changes in cloudiness at mid-latitude sites, solar UV irradiance exhibits appreciable short-term variability. One of the main advantages of the statistical method is that it uses doses of highly variable input parameters calculated from individual spot measurements taken at short time intervals, which thus do represent the short-term variability of solar irradiance. PMID:17318610

Junk, Jürgen; Feister, Uwe; Helbig, Alfred

2007-08-01

227

GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 9, PAGES 1255-1258, MAY 1, 1999 Measurements of the solar soft x-ray irradiance  

E-print Network

of the solar soft x-ray irradiance from the Student Nitric Oxide Explorer Scott M. Bailey Center of the solar soft x-ray irradiance. These measurements are carried out by a multi-channel photometer system is analyzed in terms of a solar reference spectrum in order to determine solar irradiances. The irradiances

Bailey, Scott

228

Measurements of solar irradiance and effective temperature as a probe of solar interior magnetic fields  

E-print Network

We argue that a variety of solar data suggest that the activity-cycle timescale variability of the total irradiance, is produced by structural adjustments of the solar interior. Assuming these adjustments are induced by variations of internal magnetic fields, we use measurements of the total irradiance and effective temperature over the period from 1978 to 1992, to infer the magnitude and location of the magnetic field. Using an updated stellar evolution model, which includes magnetic fields, we find that the observations can be explained by fields whose peak values range from 120k to 2.3k gauss, located in the convection zone between $0.959R_{\\sun}$ and $0.997R_{\\sun}$, respectively. The corresponding maximal radius changes, are 17 km when the magnetic field is located at $0.959R_{\\sun}$ and 3 km when it is located at $0.997R_{\\sun}$. At these depths, the $W$ parameter(defined by $\\Delta \\ln R / \\Delta \\ln L$, where $R$ and $L$ are the radius and luminosity) ranges from 0.02 to 0.006. All these predictions are consistent with helioseismology and recent measurements carried out by the MDI experiment on SOHO.

L. H. Li; S. Sofia

2000-07-14

229

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

230

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

231

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.

232

Long-term total solar irradiance variability during sunspot cycle 22  

NASA Technical Reports Server (NTRS)

Total solar irradiance measurements from the 1984-1993 Earth Radiation Budget Satellite (ERBS) active cavity radiometer and 1978-1993 Nimbus 7 transfer cavity radiometer spacecraft experiments are analyzed to detect the presence of 11-, 22-, and 80-year irradiance variability components. The analyses confirmed the existence of a significant 11-year irradiance variability component, associated with solar magnetic activity and the sunspot cycle. The analyses also suggest the presence of a 22- or 80-year variability component. The earlier Nimbus 7 and Solar Maximum Mission (SMM) spacecraft irradiance measurements decreased approximately 1.2 and 1.3 W/sq m, respectively, between 1980 and 1986. The Nimbus 7 values increased 1.2 W/sq m between 1986 and 1989. The ERBS irradiance measurements increased 1.3 W/sq m during 1986-1989, and then decreased 0.4 W/sq m (at an annual rate of 0.14 W/sq. m/yr) during 1990-1993. Considering the correlations between ERBS, Nimbus 7, and SMM irradiance trends and solar magnetic activity, the total solar irradiance should decrease to minimum levels by 1997 as solar activity decreases to minimum levels, and then increase to maximum levels by the year 2000 as solar activity rises. The ERBS measurements yielded 165.4 +/- 0.7 W/sq m as the mean irradiance value with measurement accuracies and precisions of 0.2% and 0.02%, respectively. The ERBS mean irradiance value is within 0.2% of the 1367.4, 1365.9, and 1366.9 W/sq m mean values for the SMM, Upper Atmosphere Research Satellite (UARS), and Space Shuttle Atmospheric Laboratory for Applications and Science (ATLAS 1) Solar Constant (SOLCON) active cavity radiometer spacecraft experiments, respectively. The Nimbus 7 measurements yielded 1372.1 W/sq m as the mean value with a measurement accuracy of 0.5%. Empirical irradiance model fits, based upon 10.7 -cm solar radio flux (F10) and photometric sunspot index (PSI), were used to assess the quality of the ERBS, Numbus 7, SMM, and the UARS irradiance data sets and to identify irradiance variability trends which may be caused by drifts or shifts in the spacecraft sensor responses. Comparisons among the fits and measured irradiances indicate that the Nimbus 7 radiometer response shifted by a total of 0.8 W/sq m between September 1989 and April 1990 and that the ERBS and UARS radiometers each drifted approximately 0.5 W/sq m during the first 5 months in orbit.

Lee, Robert B., III; Gibson, M. Alan; Wilson, Robert S.; Thomas, Susan

1995-01-01

233

A free real-time hourly tilted solar irradiation data Website for Europe  

E-print Network

The engineering of solar power applications, such as photovoltaic energy (PV) or thermal solar energy requires the knowledge of the solar resource available for the solar energy system. This solar resource is generally obtained from datasets, and is either measured by ground-stations, through the use of pyranometers, or by satellites. The solar irradiation data are generally not free, and their cost can be high, in particular if high temporal resolution is required, such as hourly data. In this work, we present an alternative method to provide free hourly global solar tilted irradiation data for the whole European territory through a web platform. The method that we have developed generates solar irradiation data from a combination of clear-sky simulations and weather conditions data. The results are publicly available for free through Soweda, a Web interface. To our knowledge, this is the first time that hourly solar irradiance data are made available online, in real-time, and for free, to the public. The ac...

Leloux, Jonathan; Gonzalez-Bonilla, Loreto

2014-01-01

234

Forecasting sub-hourly solar irradiance for prediction of photovoltaic output  

Microsoft Academic Search

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

Badrul H. Chowdhury; Saifur Rahman

1987-01-01

235

Oumbe A., Wald L., 2010. A parameterisation of vertical profile of solar irradiance for correcting solar fluxes for changes in terrain elevation. In Proceedings of the Earth Observation and Water Cycle Science Conference, 18-20  

E-print Network

Oumbe A., Wald L., 2010. A parameterisation of vertical profile of solar irradiance for correcting. A PARAMETERISATION OF VERTICAL PROFILE OF SOLAR IRRADIANCE FOR CORRECTING SOLAR FLUXES FOR CHANGES IN TERRAIN.wald@mines-paristech.fr ABSTRACT This paper deals with the modelling of vertical profile of solar irradiance for correcting solar

Paris-Sud XI, Université de

236

Extraterrestrial life contradicts dark energy  

NASA Astrophysics Data System (ADS)

Extraterrestrial life contradicts the Cold Dark Matter (CDM) Hierarchical Clustering (HC) model for cosmology, as well as its dark energy extension (by the 2011 Nobel Prize in Physics) to include an accelerating expansion of the universe (?CDMHC). The expansion is driven by the antigravitational property of dark energy that justified Einstein's cosmological constant (?). CDM stars appear only after a dark-age period lasting 300 Myr, rendering cosmic scale extraterrestrial life problematic. Turbulence stresses of Hydro-Gravitational-Dynamics (HGD) cosmology during the big bang are powerful but temporary, so CDM and dark energy ??are unnecessary. Superclusters fragment at 0.03 Myr. Hydrogen planets in proto-globular-star-cluster (PGC) clumps fragment protogalaxies at the transition to gas (0.3 Myr). The density at 0.03 Myr is preserved by old globular clusters (OGC) as a fossil of first fragmentation. Infrared observations support the HGD prediction (Gibson 1996) and quasar microlensing observation (Schild 1996) that the dark matter of galaxies is Earth-mass gas planets in dense PGC clumps. Water oceans seeded by dust of the first exploding stars at 2 Myr hosted extraterrestrial life spread on cosmic scales. Life anywhere falsifies dark energy.

Gibson, Carl H.

2012-10-01

237

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

238

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

239

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

240

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

241

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

242

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

243

Solar simulated radiation induced cell death depends on spectral distribution and irradiance but not output delivery.  

PubMed

Photo-biological investigations are dependent on calibration and characterisation to determine the relevance of an artificial irradiator to the study at hand. The importance of this has been voiced in the literature. However, the importance of output delivery is relatively unknown. The biological relevance of a high-energy, rapidly pulsing solar simulator was investigated using the clonogenic assay and was found to be reciprocity law compliant despite an exaggerated ultraviolet (UV) irradiance in excess of 1600 W m(-2) delivered per pulse. In fact, it was found to be the least cytotoxic irradiator compared with a second solar simulator and a UVB fluorescent lamp with continuous UV irradiances of 55 and 6.4 W m(-2), respectively. The reduced survival observed with the continuous irradiators is attributed to differences in spectral irradiance and distribution, particularly in the UVB, which in the absence of thorough calibration and characterisation may have resulted in erroneous conclusions. PMID:20203123

Maguire, Alanna; Lyng, Fiona M; Walsh, James E

2010-07-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

245

Global surface solar irradiance product derived from SCIAMACHY FRESCO cloud fraction  

NASA Astrophysics Data System (ADS)

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

Wang, Ping; Stammes, Piet; Müller, Richard

246

Measurements and models for total solar irradiance on inclined surface in Athens, Greece  

Microsoft Academic Search

This article presents a comparative assessment of tilted irradiation models, using hourly measurements of total solar irradiation on a surface tilted 50 degrees and oriented south in Athens. Detailed measurements on inclined surfaces are carried out at the National Observatory of Athens and are unique in Greece. Twelve sky diffuse submodels are used with four albedo submodels to estimate the

H. D. Kambezidis; B. E. Psiloglou; C. Gueymard

1994-01-01

247

Low Concentration Photovoltaic Systems (LCPV), where solar irradiance is concentrated by a factor of 1-10, present  

E-print Network

1 Abstract-- Low Concentration Photovoltaic Systems (LCPV), where solar irradiance is concentrated to multifactor and cyclic environmental stressors including solar irradiance, temperature and humidity which can each cause degradation over time. This issue is compounded in LCPV because concentration of solar

Rollins, Andrew M.

248

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

249

Correlations of solar irradiance and daylight illuminance for building energy analysis  

Microsoft Academic Search

The concept of luminous efficacy, the ratio of daylight illuminance to solar irradiance, is investigated for use in building energy analyses. Horizontal and vertical luminous efficacies are evaluated as functions of solar altitude, cloud condition, atmospheric extinction coefficient, turbidity, and season. Based on sky measurements made at the National Bureau of Standards, values of luminous efficacy for total, diffuse, and

G. Gillette; S. Treado

1984-01-01

250

The Nimbus 7 solar total irradiance: A new algorithm for its derivation  

Microsoft Academic Search

The Nimbus 7 satellite has measured the solar total irradiance from November 1978 to July 1991 (153 months). These measurements are important both in solar physics and for climate change. In this paper the changing radiometer pointing, the zero offsets, the stability of the gain, the temperature sensitivity, and the influences of other platform instruments are all examined and their

Douglas V. Hoyt; H. Lee Kyle; John R. Hickey; Robert H. Maschhoff

1992-01-01

251

The solar spectral irradiance and its action in the atmospheric photodissociation processes  

Microsoft Academic Search

A critical analysis is made of solar irradiance in the spectral region covering wavelengths from 100 nm upwards; the absorption characteristics of oxygen and ozone molecules are considered, and the results are applied to atmospheric photochemistry. The absorption of radiation by oxygen and ozone molecules results in their photodissociation both in the homosphere, and makes possible the penetration of solar

M. Nicolet

1981-01-01

252

Solar irradiance change and special longitudes due to r-modes  

NASA Technical Reports Server (NTRS)

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

Wolff, Charles L.; Hickey, John R.

1987-01-01

253

Combined analysis of solar neutrino and solar irradiance data: further evidence for variability of the solar neutrino flux and its implications concerning the solar core  

E-print Network

A search for any particular feature in any single solar neutrino dataset is unlikely to establish variability of the solar neutrino flux since the count rates are very low. It helps to combine datasets, and in this article we examine data from both the Homestake and GALLEX experiments. These show evidence of modulation with a frequency of 11.85 yr-1, which could be indicative of rotational modulation originating in the solar core. We find that precisely the same frequency is prominent in power spectrum analyses of the ACRIM irradiance data for both the Homestake and GALLEX time intervals. These results suggest that the solar core is inhomogeneous and rotates with sidereal frequency 12.85 yr-1. We find, by Monte Carlo calculations, that the probability that the neutrino data would by chance match the irradiance data in this way is only 2 parts in 10,000. This rotation rate is significantly lower than that of the inner radiative zone (13.97 yr-1) as recently inferred from analysis of Super-Kamiokande data, suggesting that there may be a second, inner tachocline separating the core from the radiative zone. This opens up the possibility that there may be an inner dynamo that could produce a strong internal magnetic field and a second solar cycle.

P. A. Sturrock

2008-05-23

254

Statistical characterisation of full-disk EUV/XUV solar irradiance and correlation with solar activity  

E-print Network

We investigate the distribution of fluctuations in solar irradiance when integrated over the full disk, obtained using extreme ultraviolet/soft X-ray observations from the SOHO CELIAS/SEM instrument. This time series sums over both the contributions of single distinguishable flares, and of many other processes. By detrending we select events with timescales of less than a few hours such as waves, slow flows, and CMEs. The statistics generated by this range of phenomena can be characterised by power-law-tailed distributions. We show that (i) during the high-activity period 2000 Jan-June the tail exponent a(T)=1.5 +/- 0.1; (ii) during the low-activity period 1996 Jan-June a(T)=3.0 +/- 0.2; and (iii) in general a(T) decreases with increasing activity.

J. Greenhough; S. C. Chapman; R. O. Dendy; V. M. Nakariakov; G. Rowlands

2003-02-14

255

Comment on ``Variations of Total Solar Irradiance Produced by Structural Changes in the Solar Interior''  

NASA Astrophysics Data System (ADS)

In a recent Eos article, Sofia [2004] argues for the influence on irradiance variation of global changes in the Sun's structure associated with its magnetic dynamo. These changes would act in addition to the relatively well understood modulation by dark sunspots and bright faculae at the surface. His assessment of the present observational evidence for such a global change agrees with our earlier conclusion that it is not widely convincing at the present time [Foukal, 2003]. But Sofia's article also claims (1) that the numerical results obtained by him and his collaborators at Yale disagree with and correct earlier work, and (2) that a hydrostatic approximation is not adequate for variations on the 11-year solar cycle timescale. These surprising claims are based on the results of recently published hydrostatic models [e.g., Sofia and Li, 2004] using the same mixing length approximation for convective heat transport used in earlier work [Spruit, 1982, 1991; Gilliland, 1988].

Foukal, P.; Spruit, H.

2004-12-01

256

Comparison of model estimated and measured direct-normal solar irradiance  

Microsoft Academic Search

Direct-normal solar irradiance (DNSI), the energy in the solar spectrum incident in unit time at the Earth{close_quote}s surface on a unit area perpendicular to the direction to the Sun, depends only on atmospheric extinction of solar energy without regard to the details of the extinction, whether absorption or scattering. Here we report a set of closure experiments performed in north

Rangasayi N. Halthore; Stephen E. Schwartz; Joseph J. Michalsky; Gail P. Anderson; Richard A. Ferrare; Brent N. Holben; Harry M. Ten Brink

1997-01-01

257

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

258

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.

259

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

260

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

261

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

SciTech Connect

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

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

2000-04-01

262

A model for solar spectral irradiance and radiance at the bottom and top of a cloudless atmosphere  

Microsoft Academic Search

A simple model is presented that, in a cloud-free atmosphere, calculates solar spectral direct and diffuse irradiance and directional radiance at the surface, spectral absorption within the atmosphere and the upward reflected spectral irradiance or directional radiance at the top of the atmosphere. The irradiance model, based on similar approaches by Brine and Iqbal and others, evaluates the spectral irradiances

C. G. Justus; M. V. Paris

1985-01-01

263

A I-V analysis of irradiated Gallium Arsenide solar cells  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

264

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

265

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

266

Sediment-Dispersed Extraterrestrial Chromite in Ordovician Limestone from Russia  

NASA Astrophysics Data System (ADS)

The high content of extraterrestrial chromite grains was discovered in Russian Ordovician sediments, those are coeval to Swedish limestones, bearing the fossil meteorites and extraterrestrial chromites.

Korochantsev, A. V.; Lorenz, C. A.; Ivanova, M. A.; Zaytsev, A. V.; Kononkova, N. N.; Roshchina, I. A.; Korochantseva, E. V.; Sadilenko, D. A.; Skripnik, A. Ya.

2009-03-01

267

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

NASA Technical Reports Server (NTRS)

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

Froehlich, Claus; Lean, Judith

1997-01-01

268

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

269

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.

270

Solar UV Spectral Irradiance Measurements at 0.15 nm Resolution by SUSIM  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

271

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

SciTech Connect

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

Janjai, Serm [Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000 (Thailand)

2010-09-15

272

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

273

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

274

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

275

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

276

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

277

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

278

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

279

Initial Solar Irradiance Determinations from Nimbus 7 Cavity Radiometer Measurements  

Microsoft Academic Search

Preliminary results from solar radiation measurements from the earth radiation budget experiment on the Nimbus 7 satellite yield a mean value of 1376.0 watts per square meter for the ``solar constant'' from 16 November 1978 to 15 May 1979. The observed variability (root-mean-square deviation) is ± 0.73 watt per square meter (± 0.05 percent) for the period.

J. R. Hickey; L. L. Stowe; H. Jacobowitz; P. Pellegrino; R. H. Maschhoff; F. House; T. H. Vonder Haar

1980-01-01

280

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

281

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

NASA Astrophysics Data System (ADS)

The primary energy sources of Earth's upper atmosphere are the solar irradiance and geomagnetic energy including Joule heating and particle precipitation. Various data and models are utilized to investigate the variations of energy inputs and their influences on the coupled thermosphere-ionosphere system. First, the Flare Irradiance Spectral Model (FISM) has been used and the data show that the solar irradiance enhancement has wavelength dependence during flare events, and it increased largest in the XUV range. NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) simulations for the X17.2-class flare event on October 28th, 2003 (X17.2) show that the impact of solar irradiance enhancement on the high-altitude thermosphere (400 km) is largest in the EUV wavebands instead. Secondly, the energy transfer processes into the upper atmosphere associated with high-speed solar wind stream has been investigated. It is a combination of Joule heating and particle precipitation, while Joule heating may play a more important role. We studied the high-latitude forcing from the measurements of DMSP satellite, empirical model Weimer05 and Assimilative mapping of ionospheric electrodynamics (AMIE) model. The yearly average of the northern hemisphere integrated Joule heating (IJH) calculated from AMIE is 85% larger than that from Weimer05. Thirdly, the TIE-GCM model has been used to examine the altitudinal distribution of Joule heating and its influence on the upper atmosphere. The simulation results indicate that most of the Joule heating is deposited under 150 km. For solar minimum, Joule heating above 150 km (18% of total heat) causes about 60% of the total temperature variation and 50% of the total density variation, while for solar maximum, 34% of the total heat is above 150 km and results in 90% of the temperature variation and 80% density variation. This indicates that the high-altitude Joule heating has a stronger impact on the atmosphere at 400 km. At last, the long-term variation of different energy inputs in the last solar cycle has been studied as well. The solar EUV power in last solar minimum (2008) was reduced by 33 GW compared to the previous solar minimum (1996). The reduction of the total geomagnetic energy was close to 29 GW including 13 GW for Joule heating and 16 GW for particle precipitation. The change of the geomagnetic energy from 1996 to 2008 was comparable to that of the solar EUV power. The TIE-GCM simulations indicate that the variation of the solar irradiance and the geomagnetic energy accounts for 3/4 and 1/4 of the total neutral density reduction in 2008, respectively.

Huang, Yanshi

282

Enhanced irradiance distribution on solar cell using optimized variable-focus-parabolic concentrator  

NASA Astrophysics Data System (ADS)

A solar cell concentrator system is proposed comprising a square solar cell and a variable-focus-parabolic (VFP) reflector in which the focal length varies as a function of the horizontal displacement of the incidence point relative to the vertical centerline of the solar cell. The light ray paths within the concentrator system are analyzed using an exact analytical model and a skew-ray tracing approach. The geometry of the VFP reflector is then optimized in such a way as to maximize the uniformity of the irradiance distribution on the solar cell given a circular focus spot and a square focus spot, respectively. The effectiveness of the optimized VFP reflector with a square focus spot is investigated by means of ZEMAX simulations. It is shown that the optimized VFP concentrator yields a significant improvement in the irradiance uniformity compared to that achieved using a conventional parabolic concentrator.

Tsai, Chung-Yu

2013-09-01

283

A comparison of solar irradiances measured by SBUV, SME, and rockets  

NASA Astrophysics Data System (ADS)

In this paper, Solar Backscatter Ultraviolet (SBUV) measurements of solar irradiance and predictions from the Mg 280-nm index are compared with each other and with coincident Solar Mesosphere Explorer (SME) and rocket measurements. The SBUV irradiances show a systematic decrease with time not seen in the rocket measurements; a correction for this decrease is introduced. The scatter and overall structure in the SME spectra is 3-5 percent, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1 percent. Such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the sun.

Schlesinger, Barry M.; Heath, Donald F.

1988-06-01

284

Solar-Stellar Irradiance Comparison Experiment 1. I - Instrument design and operation  

NASA Technical Reports Server (NTRS)

The main objective for the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) is to accurately measure the full disk solar spectral irradiance in the ultraviolet (UV) spectral region over a long time period. To meet this objective, SOLSTICE has the unique capability of making routine observations of the UV radiation from a set of early-type stars, using the identical optical elements and detectors employed for the solar observations. The stars selected for this calibration are assumed, on the basis of stellar evolution theory, to be extremely stable in the UV spectral region. Moreover, it is the average flux from a number of stars, perhaps from as many as 25, that is assumed to be stable. The SOLSTICE 1 is on the Upper Atmosphere Research Satellite (UARS), and the overall design and operation of the instrument are discussed. The quality of the solar and stellar data is extremely high and preliminary results indicate that the technique is working well.

Rottman, Gary J.; Woods, Thomas N.; Sparn, Thomas P.

1993-01-01

285

Effects of spatial sampling of satellite data on derived surface solar irradiance  

NASA Technical Reports Server (NTRS)

The effect of different spatial sampling of satellite observations on retrieved surface solar irradiance was studied. The results indicate that sampled (8-km resolution) and areally averaged (50-km resolution) visible brightness is highly correlated; the correlation has a regional, seasonal, and diurnal dependence. Using the two different resolutions of satellite observations, retrieved surface solar irradiance was computed for a whole annual cycle. On the average, the results differed by about 8-9 percent. Therefore, to validate satellite methods against ground truth to an accuracy which exceeds 8-9 percent of the mean, attention should be given to the type of satellite data and ground truth used in the validation process.

Pinker, R. T.; Laszlo, I.

1991-01-01

286

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

287

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

288

The recognition of extraterrestrial intelligence  

NASA Technical Reports Server (NTRS)

The departure from radiative equilibrium - represented by radio, television and radar technology - in the microwave spectrum of the earth is easily detectable over interstellar distances. Even with a technology no more advanced than our own, a civilization on a planet of a nearby star could easily determine, by auto-correlation techniques, the artificiality of these radio signals. Possible message contents for interstellar discourse of a modulated signal at any accessible frequency include (1) m-dimensional imagery represented by the transmission of numbers which are the products of m prime numbers; and (2) the use of a common mathematics, physics or astronomy to convey a range of information on more difficult subjects. The only direct attempts to date to communicate with extraterrestrial intelligence - the plaques aboard the Pioneer 10 and 11 spacecraft - are discussed briefly.

Sagan, C.

1975-01-01

289

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

290

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

Microsoft Academic Search

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

Ellsworth G. Dutton; Barry A. Bodhaine

2001-01-01

291

Correlations of solar irradiance and daylight illuminance for building energy analysis  

SciTech Connect

The concept of luminous efficacy, the ratio of daylight illuminance to solar irradiance, is investigated for use in building energy analyses. Horizontal and vertical luminous efficacies are evaluated as functions of solar altitude, cloud condition, atmospheric extinction coefficient, turbidity, and season. Based on sky measurements made at the National Bureau of Standards, values of luminous efficacy for total, diffuse, and direct beam radiation are presented.

Gillette, G.; Treado, S.

1984-10-01

292

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

293

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

294

Stratospheric chemical and thermal response to long-term variability in solar UV irradiance  

Microsoft Academic Search

Taking into account the thermal feedback effect on the reaction rates, a theoretical analysis of the chemical response of the stratosphere to the possible long-term variability of solar ultraviolet irradiance is presented. The variability, related to the 11-year solar cycle, is introduced in a two-dimensional stratosphere model simulating the zonally averaged distribution of chemical species related to oxygen, hydrogen, nitrogen

G. Brasseur; P. C. Simon

1981-01-01

295

Manuscript Submitted to Solar Energy 4/2002 A NEW OPERATIONAL SATELLITE-TO-IRRADIANCE MODEL DESCRIPTION AND VALIDATION  

E-print Network

Manuscript Submitted to Solar Energy 4/2002 A NEW OPERATIONAL SATELLITE-TO-IRRADIANCE MODEL, OR, USA #12;Manuscript Submitted to Solar Energy 4/2002 ABSTRACT We present a new simple model global and direct irradiances. The model is thoroughly validated against 10 US locations representing

Perez, Richard R.

296

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

E-print Network

Extraterrestrial Life: Problem Set #1 Due, in class, Thursday January 31st 1) Explain briefly how the terrestrial planets (such as the Earth) differ from the giant planets (such as Jupiter). Describe how to search for life? 3) Suppose that a single supernova explosion results in the ejection of 10 Solar masses

Armitage, Phil

297

Stable Isotope Variations in Extraterrestrial Materials Kevin D. McKeegan 1  

E-print Network

1 Stable Isotope Variations in Extraterrestrial Materials by Kevin D. McKeegan 1 and Laurie A bodies of the solar system contain a rich record of isotope variations in the light stable elements. As in isotope geochemistry, this record reflects physical and chemical processes involving isotopic mixing among

298

The Earth's Temperature Anomalies and the Total Solar Irradiance  

Microsoft Academic Search

The nature of the climatic response to solar variability is assessed over a long-time scale. The sun has long been suspected to influence decade-to century climate changes. One of the principal difficulties in quantifying the role of the sun in climate change has been the absence of long-term measurements of both, the climatic and solar activity phenomena. In order to

Victor Manuel Velasco Herrera

2008-01-01

299

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

300

Development of local atmospheric model for estimating solar irradiance in Peninsular Malaysia  

NASA Astrophysics Data System (ADS)

Incoming solar irradiance covers a wide range of wavelengths with different intensities which drives almost every biological and physical cycle on earth at a selective wavelength. Estimation of the intensities of each wavelength for the solar irradiance on the earth surface provides a better way to understand and predict the radiance energy. It requires that the atmospheric and geometric input and the availability of atmospheric parameter is always the main concern in estimating solar irradiance. In this study, a local static atmospheric model for Peninsular Malaysia was built to provide the atmospheric parameters in the estimation of solar irradiance. Ten years of monthly Atmospheric Infrared Sounder (AIRS) average data (water vapor, temperature, humidity and pressure profile) of the Peninsular Malaysia was used for the building of the atmospheric model and the atmospheric model were assessed based on the measured meteorological data with RMSE of 4.7% and 0.7k for both humidity and temperature respectively. The atmospheric model were applied on a well-established radiative transfer model namely SMARTS2. Some modifications are required in order to include the atmospheric model into the radiative transfer model. The solar irradiance results were then assessed with measured irradiance data and the results show that both the radiative transfer model and atmospheric model were reliable with RMSE value of 0.5 Wm-2. The atmospheric model was further validated based on the measured meteorological data (temperature and humidity) provided by the Department of Meteorology, Malaysia and high coefficient of determination with R2 value of 0.99 (RMSE value = 4.7%) and 0.90 (RMSE value = 0.7k) were found for both temperature and humidity respectively.

Yeap, E. C.; Lau, A. M. S.; Busu, I.; Kanniah, K. D.; Rasib, A. W.; Kadir, W. H. W.

2014-02-01

301

Irradiation phenomena in young solar-type stars and the early solar system: X-ray observations and ?-ray constraints  

NASA Astrophysics Data System (ADS)

The high levels of X-ray flaring activity observed in young stars and protostars suggest correspondingly high levels of low-energy particle irradiation of their circumstellar disks, and hence of early solar system material like meteorites. We first briefly review the latest X-ray observational results obtained by Chandra and XMM-Newton on two 'typical' star-forming regions, Orion and ? Ophiuchi. We then discuss a new 'accretion-ejection-irradiation-transport' model for young stars which, when scaled to the X-ray fluxes, accounts simultaneously for four extinct radioactivity ratios, in particular the purely spallogenic 10Be/ 9Be ratio, and the 26Al/ 27Al ratio. We point out the importance of the environment in which nearby star formation is taking place today, namely the Gould Belt, and the possible connection between Comptel detections of 26Al ?-ray line emission from these regions, and new constraints on the origin of the solar system.

Montmerle, Thierry

2002-07-01

302

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

of the Fermi Paradox Congressional Funding for Astrobiological Research The Ethics of Terraforming The History of SETI Extraterrestrial Life in Popular Culture The Evolution of Intelligence and Prospects of Intelligent Life in the Universe #12;

Baker, Andrew J.

303

SAS Honors Seminar 259: Extraterrestrial Life  

E-print Network

SAS Honors Seminar 259: Extraterrestrial Life 9/22/2008 #12; Star formation in Eagle Nebula) ­ background on Jupiter's moons Canup & Ward (2002) ­ proposed model for formation of Jupiter's moons ­ read

Baker, Andrew J.

304

ACRIM total solar irradiance satellite composite validation versus TSI proxy models  

E-print Network

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 TSI satellite composite was updated using corrections to ACRIMSAT/ACRIM3 results derived from recent testing at the Laboratory for Atmospheric and Space Physics/Total solar irradiance Radiometer Facility (LASP/TRF). The corrections lower the ACRIM3 scale by ~5000 ppm, in close agreement with the scale of SORCE/TIM results (solar constant ~1361 W/m^2). Relative variations and trends are not changed. Differences between the ACRIM and PMOD TSI composites, e.g. the decadal trending during solar cycles 21-22, are tested against a set of solar proxy models, including analysis of Nimbus7/ERB and ERBS/ERBE results available to bridge the ACRIM Gap (1989-1992). Our findings confirm: (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 resu...

Scafetta, Nicola

2014-01-01

305

The spectral effects of clouds on solar irradiance  

NASA Astrophysics Data System (ADS)

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

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

1998-12-01

306

Oumbe A., Blanc Ph., Schroedter-Homscheidt M., Wald L., 2010. Solar surface irradiance from new meteorological satellite data. In Proceedings of the 29th  

E-print Network

Oumbe A., Blanc Ph., Schroedter-Homscheidt M., Wald L., 2010. Solar surface irradiance from new, 320-328, doi:10.3233/978-1-60750-494-8-320 Solar surface irradiance from new meteorological satellite presents the first prototype of a new method, for assessing solar surface irradiance, benefiting from

Paris-Sud XI, Université de

307

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

308

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

Microsoft Academic Search

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

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

2006-01-01

309

Total atmospheric ozone determined from spectral measurements of direct solar UV irradiance  

Microsoft Academic Search

With a double monochromator, high resolution spectral measurements of direct solar UV-irradiance were performed in Arosa during February and March, 1993. Total atmospheric ozone amount is determined by fitting model calculations to the measured spectra. The results are compared with the operationally performed measurements of a Dobson and a Brewer spectrometer. The total ozone amount determined from spectral measurements differs

Martin Huber; Mario Blumthaler; Walter Ambach; Johannes Staehelin

1995-01-01

310

The Effect of Finite Geometry on the Three-Dimensional Transfer of Solar Irradiance in Clouds  

Microsoft Academic Search

The transfer of solar irradiance in three-dimensional clouds has been modeled by both a Monte Carlo process and an analytical technique. At the expense of considerable computation time the Monte Carlo model provides an accurate test bed of results, while for a more modest computational effort the analytical model provides approximate results which are in generally good agreement with the

R. Davies

1978-01-01

311

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

312

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

313

Influence of synoptic weather patterns on solar irradiance variability in Europe  

NASA Astrophysics Data System (ADS)

Solar radiation is important for many aspects of existence on Earth, including the biosphere, the hydrological cycle, and creatures living on the planet. Previous studies have reported decadal trends in observational records of surface shortwave (SW) irradiance around the world, too strong to be caused by varying solar output. These observed decadal trends have been dubbed "solar dimming and brightening" and are believed to be related to changes in atmospheric aerosols and cloud cover. Because the observed solar variability coincides with qualitative air pollution histories, the dimming and brightening have become almost synonymous with shortwave attenuation by anthropogenic aerosols. However, there are indications that atmospheric circulation patterns have influenced the dimming and brightening in some regions, e.g., Alaska and Scandinavia. In this work, we focus on the role of atmospheric circulation patterns in modifying shortwave irradiance. An examination of European SW irradiance data from the Global Energy Balance Archive (GEBA) shows that while there are periods of predominantly decreasing (~1970-1985) and increasing (~1985-2007) SW irradiance, the changes are not spatially uniform within Europe and in a majority of locations not statistically significant. To establish a connection between weather patterns and sunshine, regression models of SW irradiance are fitted using a daily classification of European weather called Grosswetterlagen (GWL). The GWL reconstructions of shortwave irradiance represent the part of the solar variability that is related to large scale weather patterns, which should be effectively separated from the influence of varying anthropogenic aerosol emissions. The correlation (R) between observed and reconstruced SW irradiance is between 0.31 and 0.75, depending on station and season, all statistically significant (p<0.05, estimated with a bootstrap test). In central and eastern parts of Europe, the observed decadal SW variability is poorly represented by the GWL models, but in northern Europe, the GWL model recreates observed decadal solar variability well. This finding suggests that natural and/or anthropogenic variations in circulation patterns have influenced solar dimming and brightening to a higher degree in the north than in the rest of Europe.

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

2014-05-01

314

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

315

Are Non-Magnetic Mechanisms Such As Temporal Solar Diameter Variations Conceivable for an Irradiance Variability?  

NASA Astrophysics Data System (ADS)

Irradiance variability has been monitored from space for more than two decades. Even though data come from different sources, it is well established that a temporal variability exists ?0.1%, in phase with the solar cycle. Today, one of the best explanations for such an irradiance variability is provided by the evolution of the solar surface magnetic fields. But if some 90 95% can be reproduced, what would be the origin of the 10 5% left? Non-magnetic effects are conceivable. In this paper we will consider temporal variations of the diameter of the Sun as a possible contributor for the remaining part. Such an approach imposes strong constraints on the solar radius variability. We will show that over a solar cycle, variations of no more than 20 mas of amplitude can be considered. Such a variability far from what is reported by observers conducting measurements by means of ground-based solar astrolabes may explain a little part of the irradiance changes not explained by magnetic features. Further, requirements are needed that may help to reach a conclusion. Dedicated space missions are necessary (for example PICARD, GOLF-NG or SDO, scheduled for a launch around 2008); it is also proposed to reactivate SDS flights for such a purpose.

Rozelot, J. P.; Lefebvre, S.; Pireaux, S.; Ajabshirizadeh, A.

2004-10-01

316

Are non-magnetic mechanisms such as temporal solar diameter variations conceivable for an irradiance variability?  

E-print Network

Irradiance variability has been monitored from space for more than two decades. Even if data are coming from different sources, it is well established that a temporal variability exists which can be set to as approximately 0.1%, in phase with the solar cycle. Today, one of the best explanation for such an irradiance variability is provided by the evolution of the solar surface magnetic fields. But if some 90 to 95% can be reproduced, what would be the origin of the 10 to 5% left? Non magnetic effects are conceivable. In this paper we will consider temporal variations of the diameter of the Sun as a possible contributor for the remaining part. Such an approach imposes strong constraints on the solar radius variability. We will show that over a solar cycle, variations of no more than 20 mas of amplitude can be considered. Such a variability (far from what is reported by observers conducting measurements by means of ground-based solar astrolabes) may explain a little part of the irradiance changes not explained by magnetic features. Further requirements are needed that may help to reach a conclusion. Dedicated space missions are necessary (for example PICARD, GOLF-NG or SDO, scheduled for a launch around 2008); it is also proposed to reactivate SDS flights for such a purpose.

J. P. Rozelot; S. Lefebvre; S. Pireaux; A. Ajabshirizadeh

2006-01-05

317

The dependence of the surface solar irradiance on cloud and aerosol  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

318

Life from the stars?. [extraterrestrial sources contributing to chemical evolution on Earth  

NASA Technical Reports Server (NTRS)

Scientists are now seriously considering the possibility that organic matter from interstellar space could have influenced, or even spurred, the origin of life on Earth. Various aspects of chemical evolution are discussed along with possible extraterrestrial sources responsible for contributing to Earth's life-producing, chemical composition. Specific topics covered include the following: interstellar matter, molecular clouds, asteroid dust, organic molecules in our solar system, interplanetary dust and comets, meteoritic composition, and organic-rich solar-system bodies.

Pendleton, Yvonne J.; Cruikshank, Dale P.

1994-01-01

319

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

320

Geiger M., Diabat L., Mnard L., Wald L., 2002. A web service for controlling the quality of measurements of global solar irradiation. Solar Energy, Vol. 73, No 6, pp. 475-480  

E-print Network

of measurements of global solar irradiation. Solar Energy, Vol. 73, No 6, pp. 475-480 Copyright Ecole des Mines de-480" #12;A web service for controlling the quality of global solar irradiation Copyright Ecole des Mines de Paris -Armines - UFAE 1 A WEB SERVICE FOR CONTROLLING THE QUALITY OF MEASUREMENTS OF GLOBAL SOLAR

Paris-Sud XI, Université de

321

Viable photocatalysts under solar-spectrum irradiation: nonplasmonic metal nanoparticles.  

PubMed

Supported nanoparticles (NPs) of nonplasmonic transition metals (Pd, Pt, Rh, and Ir) are widely used as thermally activated catalysts for the synthesis of important organic compounds, but little is known about their photocatalytic capabilities. We discovered that irradiation with light can significantly enhance the intrinsic catalytic performance of these metal NPs at ambient temperatures for several types of reactions. These metal NPs strongly absorb the light mainly through interband electronic transitions. The excited electrons interact with the reactant molecules on the particles to accelerate these reactions. The rate of the catalyzed reaction depends on the concentration and energy of the excited electrons, which can be increased by increasing the light intensity or by reducing the irradiation wavelength. The metal NPs can also effectively couple thermal and light energy sources to more efficiently drive chemical transformations. PMID:24604813

Sarina, Sarina; Zhu, Huai-Yong; Xiao, Qi; Jaatinen, Esa; Jia, Jianfeng; Huang, Yiming; Zheng, Zhanfeng; Wu, Haishun

2014-03-10

322

Solar irradiance and the development of endomycorrhizal green ash seedlings.  

PubMed

We investigated the effects and interaction of four irradiances, 37, 53, 70 and 100% full sunlight, and the endomycorrhizae Glomus macrocarpum and Glomus fasciculatum on the development of seedlings of Fraxinus pennsylvanica Marsh. At all irradiances, mycorrhizal seedlings were taller and larger in diameter than nonmycorrhizal seedlings. Seedlings inoculated with G. macrocarpum showed the best height growth at 70% or less of full sunlight, whereas seedlings inoculated with G. fasciculatum grew best at 37 and 53% full sunlight. Leaf area was greatest in shaded seedlings and was enhanced by mycorrhizal inoculation. Shoot/root ratios were greater for mycorrhizal than for nonmycorrhizal seedlings. At intermediate light intensities, percent root length colonized was greatest, whereas the concentrations of soluble sugar and starch in roots were at intermediate levels. PMID:14969881

Borges, R G; Chaney, W R

1993-10-01

323

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

324

Measurements of spectral solar UV irradiance in tropical-Australia  

Microsoft Academic Search

Measurements of global spectral irradiance in the UV and visible range were carried out during December 1995 and January 1996 in Townsville, Australia (19.33øS, 146.76øE, 30 m above sea level (asl)) using the mobile spectroradiometer of the Fraunhofer Institute for Atmospheric Environmental Research, Germany. These are, to our knowledge, the first reported spectral UV measurements in the tropics of Australia.

G. Bernhard; B. Mayer; G. Seckmeyer; A. Moise

1997-01-01

325

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

326

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

327

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

NASA Technical Reports Server (NTRS)

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

Noyes, Robert W.

1987-01-01

328

Particle–gas reacting flow under concentrated solar irradiation  

Microsoft Academic Search

A transient heat transfer model is developed for a reacting flow of CH4 laden with carbon particles directly exposed to concentrated solar radiation and undergoing thermal decomposition into carbon and hydrogen. The unsteady mass and energy conservation equations, coupling convective heat and mass transfer, radiative heat transfer, and chemical kinetics for a two-phase solid–gas flow, are formulated and solved numerically

G. Maag; W. Lipi?ski; A. Steinfeld

2009-01-01

329

Solar ultraviolet irradiance and cancer incidence and mortality.  

PubMed

The solar ultraviolet-B (UVB)/vitamin D/cancer hypothesis was proposed by the brothers Cedric and Frank Garland in 1980. In 2002, the list was increased to 15 types of cancer using data in the 1999 version of the atlas of cancer mortality rates in the United States. Ecological studies of cancer incidence and/or mortality rates with respect to indices of solar UVB doses have also been reported for Australia, China, France, Japan, and Spain with largely similar findings. In addition, several studies using nonmelanoma skin cancer as the index of solar UVB dose have found reduced internal cancer incidence and/or mortality rates, especially in sunny countries. A study of cancer incidence with respect to 54 categories of occupation in five Nordic countries, using lip cancer less lung cancer as the UVB index, found this index inversely correlated with 14 types of internal cancers for males and four for females. Observational studies with respect to UVB doses and serum 25-hydroxyvitamin D [25(OH)D] concentrations also support the hypothesis. Hill's criteria for causality in a biological system to assess whether solar UVB and vitamin D can be considered causal in reducing risk of cancer. The primary criteria for this analysis include strength of association, consistent findings in different populations, biological gradient, plausibility (e.g., mechanisms), and experimental verification (e.g., randomized controlled trials). The totality of evidence is judged to satisfy the criteria very well for breast and colorectal cancer, and moderately well for several other types of cancer. PMID:25207360

Grant, William B

2014-01-01

330

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

331

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

332

The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells  

NASA Astrophysics Data System (ADS)

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

Jayashree, B.; Ramani; Radhakrishna, M. C.; Agrawal, Anil; Khan, Saif Ahmad; Meulenberg, A.

2006-12-01

333

The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells  

E-print Network

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

B. Jayashree; Ramani; M. C. Radhakrishna; Anil Agrawal; Saif Ahmad Khan; A. Meulenberg

2006-10-20

334

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

335

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

336

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

337

Measurement and modeling of solar irradiance components on horizontal and tilted planes  

SciTech Connect

In this work new measurements of global and diffuse solar irradiance on the horizontal plane and global irradiance on planes tilted at 20 and 30 oriented due South and at 45 and 65 oriented due East are used to discuss the modeling of solar radiation. Irradiance data are collected in Padova (45.4 N, 11.9 E, 12 m above sea level), Italy. Some diffuse fraction correlations have been selected to model the hourly diffuse radiation on the horizontal plane. The comparison with the present experimental data shows that their prediction accuracy strongly depends on the sky characteristics. The hourly irradiance measurements taken on the tilted planes are compared with the estimations given by one isotropic and three anisotropic transposition models. The use of an anisotropic model, based on a physical description of the diffuse radiation, provides a much better accuracy, especially when measurements of the diffuse irradiance on the horizontal plane are not available and thus transposition models have to be applied in combination with a diffuse fraction correlation. This is particularly significant for the planes oriented away from South. (author)

Padovan, Andrea; Col, Davide del [Dipartimento di Fisica Tecnica, Universita degli Studi di Padova (Italy)

2010-12-15

338

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

339

Radiance And Irradiance Of The Solar HeII 304 Emission Line  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

340

Estimating integrated cloud liquid water from extended time observations of solar irradiance  

NASA Technical Reports Server (NTRS)

An analysis technique used to estimate the integrated liquid water content (LWC) from the measured solar irradiance is described. The cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the same time on a cloudless day. From the transmittance and the zenith angle, the cloud LWC is computed using the radiative transfer parameterizations of Stephens et al., (1984). The results are compared with 17 days of mm-wave (20.6 and 31.65 GHz) radiometer measurements made during the First ISCCP Regional Experiment (FIRE) Intensive Field Observation (IFO) in July of 1987.

Fairall, C. W.; Rabadi, Raja El-Salem; Snider, Jack B.

1990-01-01

341

Observations of the Spectral Distribution of Solar Irradiance at the Ground During SUCCESS  

NASA Technical Reports Server (NTRS)

During SUCCESS two independent and independently calibrated spectrometers were deployed at a surface site to determine the spectrally resolved downwelling solar irradiance. Preliminary evidence shows that for cloud-free conditions there is general agreement between measurements and model derived irradiance, at least to within instrumental and model uncertainties of 5%, with greatest disagreement Occurring in the 400 nm - 700 nm band. Cirrus effects are most prominent in the near-infrared bands beyond 1500 nm while the influence of very thin (subvisual) cirrus is evident in the scattered flux at the surface. Further remote sensing applications and the assessment of cloud absorption is contingent upon measurements of the surface spectral albedo.

Pilewskie, Peter; Goetz, Alexander F. H.; Beal, David A.; Bergstrom, Robert W.; Mariani, Peter

1998-01-01

342

Monitor PHOKA for solar XUV/EUV irradiation measurement onboard Coronas-Photon mission  

NASA Astrophysics Data System (ADS)

PHOKA is one of the scientific instruments onboard solar satellite Coronas-Photon. The instrument registries fluxes of solar disks radiation in two EUV bands (1-11nm and 27-37nm) and in Ly-?band (121.6nm). Minimum accumulating time of the fluxes is 0.1sec. The silicon Absolute XUV photodiodes AXUV-50(have been fabricated by IRD) are used in PHOKA. AXUV have one hundred percent internal carrier collection efficiency in EUV/XUV region. For blocking of light that is out of the measured EUV band the photodiodes have directly deposited metal filters: Ni-Pd for 1-11nm band and Cr/al for 27-37nm. The Cr/Al devices have at least 7 orders of magnitude visual light blocking. For the Ti/Pd filters the visual light blocking of six order magnitude is achieved. For measuring of visible light background signal the fused silica filters are used. Fused silica filters are placed in filter wheel. Different wheel positions correspond to different PHOKA operation regimes. In Ly-? channel (measuring solar irradiation at 121.6nm) the bare photodiode AXUV and two external filters Acron 122-XN-).5D are used. To ensure the flux measurements with good absolute accuracy the filtered photodiodes are calibrating at synchrotron radiation devices in VNIIOFI (Moscow) and PRB (Germany). The satellite will be launch in autumn season this year to 550km circular orbit with inclination 82.5 degrees. PHOKA instrument Data will be used for studying of development of solar flares and variation of solar irradiation over a long period. During entering and leaving the Earth shadow the instrument will measure solar irradiation passed throw the upper Earth atmosphere (for making occultation measurements to study of the Earth upper atmosphere layers). Detailed description of the instrument, used operation regimes, results of calibration and estimated values of signal/background will be presented and discussed in the report.

Kotov, Yury; Kochemasov, Alexey; Yurov, Vitaly; Korde, Raj

343

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

344

Solar Gravity Modes from ACRIM-SMM Irradiance Data  

NASA Technical Reports Server (NTRS)

The record of 280 days of continuous data of the ACRIM radiometer on board the Solar Maximum Mission satellite is analyzed in the frequency range from 10 to 80 micro Hz. Gravity modes of degree one and two with orders from about 10 to several hundreds can be localized. A statistical method to determine the fundamental period T sub 0 and the rate of rotation upsilon sub R as seen by rotational splitting is described and the results for 33.5 T sub 0 45.5 minutes and 0.4 upsilon sub R micro Hz are presented. They indicate a rather high T sub 0 and it cannot be excluded that it is above the upper limit analyzed.

Frohlich, C.; Delache, P.

1984-01-01

345

Solar ultraviolet irradiance observed from Southern Argentina; September 1990 to March 1991  

Microsoft Academic Search

A nearly continuous data set of solar ultraviolet spectra irradiance exists for Ushuaia, Argentina, latitude 54°59' S, over the period from mid-September 1990 to mid-March 1991. This includes a season of prolonged depletion in column ozone over Antarctica, 10° or more in latitude poleward of Ushuaia. Cloudiness provides a major source of variance in the measurements. When this influence is

J. E. Frederick; P. F. Soulen; S. B. Diaz; I. Smolskaia; C. R. Booth; T. Lucas; D. Neuschuler

1993-01-01

346

Comparison of spectral direct and diffuse solar irradiance measurements and calculations for cloud?free conditions  

Microsoft Academic Search

Ground-based spectral measurements of direct and diffuse solar irradiance from the Rotating Shadowband Spectroradiometer, taken in cloud-free conditions in Oklahoma in the fall of 1997, are compared over the spectral range 10000-28500 cm-1 to corresponding calculations by an accurate multiple-scattering radiative transfer model. For each case analyzed, the aerosol optical depths used in the calculation were determined by fitting an

Eli J. Mlawer; Patrick D. Brown; Shepard A. Clough; Lee C. Harrison; Joseph J. Michalsky; Piotr W. Kiedron; Tim Shippert

2000-01-01

347

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

Microsoft Academic Search

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

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

2002-01-01

348

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

349

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

350

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

SciTech Connect

Terrestrial far ultraviolet (FUV) airglow emissions have been suggested as a means for remote sensing the structure of the upper atmosphere. The energy which leads to the excitation of FUV airglow emissions is solar irradiance at extreme ultraviolet (EUV) and soft x-ray wavelengths. Solar irradiance at these wavelengths is known to be highly variable; studies of nitric oxide (NO) in the lower thermosphere have suggested a variability of more than an order of magnitude in the solar soft x-ray irradiance. To properly interpret the FUV airglow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N2 to infer the flux of photoelectrons in the atmosphere and thus to infer the magnitude of the solar irradiance. This dissertation presents the first simultaneous measurements of the FUV airglow, the major atmospheric constituent densities, and the solar EUV and soft x-ray irradiances. The measurements were made on three flights of an identical sounding rocket payload at different levels of solar activity. The linear response in brightness of the LBH bands to variations in solar irradiance is demonstrated. In addition to the N2 LBH bands, atomic oxygen lines at 135.6 and 130.4 nm are also studied. Unlike the LBH bands, these emissions undergo radiative transfer effects in the atmosphere. The OI emission at 135.6 nm is found to be well modeled using a radiative transfer calculation and the known excitation processes. Unfortunately, the assumed processes leading to OI 130.4 nm excitation are found to be insufficient to reproduce the observed variability of this emission. Production of NO in the atmosphere is examined; it is shown that a lower than previously reported variability in the solar soft x-ray irradiance is required to explain the variability of NO.

Bailey, S.M.

1995-01-01

351

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

352

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

353

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

354

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 1x1016 e/cm2 and 10 MeV protons with a fluence exceeding 1x1013 p/cm2. 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 (CI-OI). 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).

Tsukamoto, K.; Matsuda, S.; Kawasaki, O.; Hisamatsu, T.

1999-01-01

355

Comparison of the Changes in the Visible and Infrared Irradiance Observed by the SunPhotometers on EURECA to the UARS Total Solar and UV Irradiances  

NASA Technical Reports Server (NTRS)

Solar irradiance in the near-UV (335 nm), visible (500 nm) and infrared (778 nm) spectral bands has been measured by the SunPhotometers developed at the World Radiation Center, Davos, Switzerland on board the European Retrievable Carrier between August 1992 and May 1993. Study of the variations in the visible and infrared irradiance is important for both solar and atmospheric physics. The purpose of this paper is to examine the temporal variations observed in the visible and infrared spectral bands after eliminating the trend in the data mainly related to instrument degradation. The effect of active regions in these spectral irradiances is clearly resolved. Variations in the visible and infrared irradiances are compared to total solar irradiance observed by the SOVA2 radiometer on the EURECA platform and by the ACRIMII radiometer on UARS as well as to UV observations of the UARS and NOAA9 satellites. The space-borne spectral irradiance observations are compared to the photometric sunspot deficit and CaII K irradiance measured at the San Fernando Observatory, California State University at Northridge in order to study the effect of active regions in detail.

Pap, Judit

1995-01-01

356

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

357

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

358

Long-Term Total Solar Irradiance (TSI) Variability Trends: 1984-2004  

NASA Technical Reports Server (NTRS)

The incoming total solar irradiance (TSI), typically referred to as the solar constant, is being studied to identify long-term TSI changes, which may trigger global climate changes. The TSI is normalized to the mean earth-sun distance. Studies of spacecraft TSI data sets confirmed the existence of 0.1 %, long-term TSI variability component with a period of 10 years. The component varied directly with solar magnetic activity associated with recent 10-year sunspot cycles. The 0.1 % TSI variability component is clearly present in the spacecraft data sets from the 1984-2004, Earth Radiation Budget Experiment (ERBE) active cavity radiometer (ACR) solar monitor; 1978-1993, Nimbus-7 HF; 1980-1989, Solar Maximum Mission [SMM] ACRIM; 1991-2004, Upper Atmosphere Research Satellite (UARS) ACRIM; 1996-2003, Solar and Heliospheric Observatory (SOHO)/VIRGO, Space Science (ATLAS), 2000-2004, ACRIMSAT; and 2003-2004 SOlar Radiation and Climate Experiment (SORCE) active cavity radiometer (ACR) missions. From October 1984, through March 2004, the ERBS/ERBE solar monitor was used to produce the longest continuous data set of total solar irradiance (TSI) variability measurements. The solar monitor is located on Shuttle Atmospheric Laboratory for Applications and the NASA Earth Radiation Budget Satellite (ERBS). Maximum TSI values occurred during the 1989-1991, and 1998-2002, time frames; while minimum [quiet sun] TSI levels occurred during 1986 and 1996. Recent ERBS measurements indicate that the TSI is decreasing to forecasted, minimum levels by 2006. Using the discontinuous non-operational Nimbus-7, SMM ACRIM, and UARS ACRIM mission TSI data sets, Wilson and Mordvinor (2003) suggested the existence of an additional long-term TSI variability component, 0.05 %, with a period longer than a decade. Analyses of the ERBS/ERBE data set do not support the Wilson and Mordvinor analyses approach because it used the Nimbus-7 data set which exhibited a significant ACR response shift of 0.7 Wm-2

Lee, Robert Benjamin, III; Wilson, Robert S.; Thomas, Susan

2004-01-01

359

The Visible Solar Spectral Irradiance from 350 to 850 nm As Measured by the SOLSPEC Spectrometer During the ATLAS I Mission  

Microsoft Academic Search

The SOLSPEC instrument has been built to carry out solar spectral irradiance measurements from 200 to 3000 nm. It consists of three spectrometers designed to measure the solar spectral irradiance in ultraviolet, visible, and infrared domains. It flew with the ATLAS I mission in March 1992. This paper is dedicated to the visible part of the solar spectrum. Comparisons with

Gerard Thuillier; Michel Herse; Paul C. Simon; Dietrich Labs; Holger Mandel; Didier Gillotay; Thomas Foujols

1998-01-01

360

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

361

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

362

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

363

Variation of incoming solar radiation flux during a partial eclipse episode: an improved model simulation  

E-print Network

Model simulations of solar irradiance reaching the Earth's surface during a solar eclipse constitute a useful tool for studying the impact of this phenomenon on the radiance propagation through the atmosphere. A simple approach to extend the use of an algorithm already adopted for evaluating the variations in the extraterrestrial solar radiation during a total eclipse is proposed for a partial eclipse case. The application is based on the assessment of the distance between the apparent solar and lunar disk centers on the celestial hemisphere, using the local circumstances and the ratio between the Sun and Moon radii as input parameters. It was found that during the eclipse of March 29, 2006, the present approach led to an estimate of the surface UV solar irradiance trend differing by no more than \\pm5% from the corresponding trend observed at Bologna (Italy).

Petkov, Boyan; Vitale, Vito; Lanconelli, Christian; Mazzola, Mauro

2011-01-01

364

A New Relation between Central and Total Solar H I Lyman-? Irradiances, as measured by SOHO during Solar Cycle 23 (1996-2003)  

NASA Astrophysics Data System (ADS)

The spectral irradiance at the center of the solar H Ly-? line profile is the main excitation source responsible for the atomic hydrogen resonant scattering in cool material. It has therefore to be known with the best possible accuracy to model the H Ly-? emissions taking place in planetary, cometary and interplanetary environments. On the other hand, the only permanently monitored solar irradiance is the total one - either measured by near-Earth satellites, or deduced from its correlation with solar activity indexes. It is the reason why Vidal-Madjar (1975) using OSO-5 satellite H Ly-? data, established a semi-empirical formula allowing to deduce the central H Ly-? irradiance from the integrated one. This relation has been extensively used for three decades. In fact, at the low altitude of the OSO-5 orbit, the observed central part of the solar line profiles was deeply absorbed by a large column of exospheric atomic hydrogen. Consequently, the solar line center irradiances were not measured directly, but obtained by confronting the measurements with simulations of both the geocoronal absorption and the self-reversed shape of the central solar profile itself. On the contrary, the SOHO/SUMER spectrometer orbiting well outside the H geocoronal envelope (at the L1 Sun-Earth Lagrange point), provided full Sun H Ly-? profiles, exempt from any central geocoronal absorption (Lemaire et al. (1998, 2002, 2004)). This has made it possible to directly measure the central H Ly-? solar irradiances as a function of the integrated ones, during eight years of Solar Cycle 23. The newly obtained relation confirms the general trend of the previous one, but it is characterized by significantly different coefficients. It will therefore provide new and more accurate inputs for the future modeling of the various Ly-? emissions occurring inside the Solar System.

Emerich, C.; Lemaire, P.; Vial, J.-C.; Curdt, W.; Schüle, U.; Wilhelm, K.

2004-05-01

365

Extraterrestrial amino acids and terrestrial life  

NASA Astrophysics Data System (ADS)

Since the Swedish chemist Baron Jöns Jacob Berzelius first analysed the Alais meteorite for organic molecules' in 1834, attempts to forge a link between extraterrestrial organic materials and terrestrial life have remained alluring, but often deceptive. New studies reported in this and last week's issues hold the promise of important advances in both endeavours. (AIP)

Chyba, Christopher F.

1996-07-01

366

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.

367

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

& Shostak 7.3, 9.19.2 ­ possibility of life on Europa, as well as the other moons of Jupiter articles from SAS Honors Seminar 256: Extraterrestrial Life 10/20/2011 #12; Midterm project data Option.3 ­ possibility of life on Titan, as well as the other moons of Saturn, Uranus, and Neptune articles from

Baker, Andrew J.

368

Conway Morris: Extraterrestrials: Aliens like us?  

NASA Astrophysics Data System (ADS)

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

Morris, Simon Conway

2005-08-01

369

SAS Honors Seminar 259: Extraterrestrial Life  

E-print Network

& Randolph (2002) ­ thoughts on discovery of extraterrestrial (un)intelligence Fogg (2000) ­ thoughts images of extrasolar planets (b) recent Mars lander/rover missions (c) life in terran ice (d) highlights no .docx!) Late policy: usual 10% per day Contribution to course grade: 30% #12; Term paper: evaluation

Baker, Andrew J.

370

Solar System Searches for Life  

Microsoft Academic Search

Exobiology--the search for extraterrestrial life and the study of conditions relevant to its origins--has been reborn in the past decade. This rebirth has been driven largely by discoveries related to Earth's deep biosphere, and the recognition that there may be several extraterrestrial environments within our own Solar System that could provide plausible environments for subsurface ecologies. Most prominent among these

C. F. Chyba

1998-01-01

371

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

372

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

NASA Astrophysics Data System (ADS)

The spectral irradiance at the center of the solar H I Lyman ? ( ?=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? emissions taking place in planetary, cometary, and interplanetary environments. Since the only permanently monitored solar irradiance is the total one (i.e. integrated over the whole Ly? line profile), Vidal-Madjar [1975. Evolution of the solar Lyman alpha flux during four consecutive years. Solar Phys. 40, 69-86] using Orbiting Solar Observatory 5 (OSO-5) satellite Ly? data, established a semi-empirical formula allowing him to deduce the central spectral Ly? irradiance from the total one. This relation has been extensively used for three decades. But, at the low altitude of the OSO-5 orbit, the central part of the solar line profile was deeply absorbed by a large column of exospheric atomic hydrogen. Consequently, the spectral irradiance at the center of the line was obtained by a complex procedure confronting the observations with simulations of both the geocoronal absorption and the self-reversed shape of the solar Ly? profile. The SUMER spectrometer onboard SOHO positioned well outside the hydrogen geocorona, provided full-Sun Ly? profiles, not affected by such an absorption [Lemaire et al., 1998. Solar H I Lyman ? full disk profile obtained with the SUMER/SOHO spectrometer. Astron. Astrophys. 334, 1095-1098; 2002. Variation of the full Sun Hydrogen Lyman ? and ? profiles with the activity cycle. Proc. SOHO 11 Symposium, ESA SP-508, 219-222; 2004. Variation of the full Sun Hydrogen Lyman profiles through solar cycle 23. COSPAR 2004 Meeting], making it—for the first time—possible to measure the spectral and total Ly? solar irradiances directly and simultaneously. A new relation between these two quantities is derived in an expression that is formally similar to the previous one, but with significantly different parameters. After having discussed the potential causes for such differences, it is suggested that the new relation should replace the old one for any future modeling of the numerous Ly? absorptions and emissions observed in the Solar System.

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

2005-11-01

373

Extraterrestrial Helium Trapped in Fullerenes in the Sudbury Impact Structure  

NASA Technical Reports Server (NTRS)

Fullerenes (C60 and C70) in the Sudbury impact structure contain trapped helium with a He-3/He-4 ratio of 5.5 x 10(exp -4) to 5.9 x 10(exp -4). The He-3/He-4 ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The He-3/He-4 ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C60 molecules at Sudbury is of extraterrestrial origin.

Becker, Luann; Poreda, Robert J.; Bada, Jeffrey L.

1996-01-01

374

Processing of extraterrestrial materials by high temperature vacuum vaporization  

NASA Technical Reports Server (NTRS)

It is noted that problems associated with the extraction and concentration of elements and commpounds important for the construction and operation of space habitats have received little attention. High temperature vacuum vaporization is considered a promising approach; this is a technique for which the space environment offers advantages in the form of low ambient pressures and temperatures and the possibility of sustained high temperatures via solar thermal energy. To establish and refine this new technology, experimental determinations must be made of the material release profiles as a function of temperature, of the release kinetics and chemical forms of material being transported, and of the various means of altering release kinetics. Trace element data determined by neutron activation analysis of meteorites heated to 1400 C in vacuum is summarized. The principal tool, high temperature spectrometry, is used to examine the vaporization thermodynamics and kinetics of major and minor elements from complex multicomponent extraterrestrial materials.

Grimley, R. T.; Lipschutz, M. E.

1983-01-01

375

Extraterrestrial Organic Matter: A review  

NASA Astrophysics Data System (ADS)

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, William M.

1998-10-01

376

Accuracy of CM-SAF solar irradiance incident on horizontal surface  

NASA Astrophysics Data System (ADS)

The Climate Monitoring Satellite Application Facility (CM-SAF) provides estimates of global solar irradiance incident on horizontal surface at Earth surface. Measurements performed in 2010 at five Romanian meteorological stations are used to test the accuracy of the CM-SAF irradiance data. The dataset contains null solar global irradiance values, which cannot be explained by very large values of the zenith angle neither by overcast sky conditions. Sub-databases have been created. The database Z85 consists of irradiance data, without filtering and processing. The database Z85SIS+ remove all null irradiance values. For a given database, the root mean square error (RMSE) with respect to the ground-based measurements is rather similar for all stations, i.e. around 35 % for Z85 and 24 % for Z85SIS+. On average, the database Z85SIS+ has smaller mean bias error (MBE) than the database Z85, independent of the degree of cloudiness. For the database Z85, MBE (RMSE) ranges, depending on station, between -9.4 and -1.2 % (35.3 and 39.1 %). For database Z85SIS+, the MBE (RMSE) ranges, depending on station, between -4.0 and 0.1 % (23.0 and 29.1 %). On overcast sky, we found for some stations MBE = -0.1 % and RMSE = 46.4 % when the database Z85SIS+ has been considered. The accuracy of the database Z85 is lower; we found MBE = -7.0 % and RMSE = 58.8 % as extreme cases.

Badescu, Viorel; Dumitrescu, Alexandru

2014-07-01

377

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

2013-12-02

378

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

379

[Spectral scanning measurement of high-precision solar irradiance-meter].  

PubMed

In order to measure the radiation of the sun absolutely and retrieve the characterization of the atmosphere precisely, a high-precision solar spectral irradiance meter working in 0.4-1.0 microm band was developed. A Fèry prism was employed to disperse the incident sunlight and a closed-loop control method was adopted for spectral scanning in this solar irradiance meter. The design of spectral scanning measurement was depicted in detail. The design requirements of Fèry prism were given and spectral dispersion was achieved by single element. The trap detectors were used to ensure precise spectral measurement. According to the parameters of the trap detectors, the demands and method of temperature control were introduced. The design of spectral scanning structure was introduced, and wavelengths were positioned accurately. The requirements for parameters, stability and power supply of voice coil actuator were given and the wavelength position error of 0. 025% was achieved. Spectral scanning measurement of 0.4-1.0 microm was accomplished in outdoor experiments. A comparison was carried out with visible-short wave infrared spectrometer and auto-sunphotometer (CE318). Results indicate that absorption peak locations of spectral scanning measurement of irradiance meter are correct, and the relative deviation from CE318 measurements is less than 0.13% for all day, and the relative deviation of optical depth in visible and near infrared band is less than 2% and 5%, respectively. PMID:25208375

Liu, En-Chao; Li, Xin; Zhang, Yan-Na; Li, Wen-Wei; Zheng, Xiao-Bing

2014-03-01

380

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

E-print Network

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.

Yvonne C. Unruh; Natalie A. Krivova; Sami K. Solanki; Jerald W. Harder; Greg Kopp

2008-02-28

381

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

382

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

383

Assessing Surface Solar Irradiance From ISCCP-B2 Data Sets Lefvre M., Diabat L., Wald L., Using reduced data sets ISCCP-B2 from the Meteosat satellites to  

E-print Network

Assessing Surface Solar Irradiance From ISCCP-B2 Data Sets Lefèvre M., Diabaté L., Wald L., Using reduced data sets ISCCP-B2 from the Meteosat satellites to assess surface surface solar irradiance. Solar THE METEOSAT SATELLITES TO ASSESS SURFACE SOLAR IRRADIANCE M. Lefèvre (1), L. Wald (1), L. Diabaté (2) (1

Paris-Sud XI, Université de

384

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

385

Silicon solar cell characterization at low temperatures and low illumination as a function of particulate irradiation  

NASA Technical Reports Server (NTRS)

Various configurations of back surface reflector silicon solar cells including small (2 x 2) cm and large (approx. 6 x 6) cm cells with conventional and wraparound contacts were subjected to 1 MeV electron irradiation and characterized under both Earth orbital and deep space conditions of temperatures and illuminations. Current-Voltage (I-V) data were generated from +65 C to -150 C and at incident illuminations from 135.3 mW/sq cm to 5.4 mW/sq cm for these cells. Degradation in cell performance which is manifested only under deep space conditions is emphasized. In addition, the effect of particle irradiation on the high temperature and high intensity and low temperature and low intensity performance of the cells is described. The cells with wraparound contacts were found to have lower efficiencies at Earth orbital conditions than the cells with conventional contacts.

Whitaker, A. F.; Little, S. A.; Peacock, C. L., Jr.

1983-01-01

386

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

387

Determination of Semivariogram Models to Krige Hourly and Daily Solar Irradiance in Western Nebraska(.  

NASA Astrophysics Data System (ADS)

In this paper, linear and spherical semivariogram models were determined for use in kriging hourly and daily solar irradiation for every season of the year. The data used to generate the models were from 18 weather stations in western Nebraska. The models generated were tested using cross validation. The performance of the spherical and linear semivariogram models were compared with each other and also with the semivariogram models based on the best fit to the sample semivariogram of a particular day or hour. There were no significant differences in the performance of the three models. This result and the comparable errors produced by the models in kriging indicated that the linear and spherical models could be used to perform kriging at any hour and day of the year without deriving an individual semivariogram model for that day or hour.The seasonal mean absolute errors associated with kriging, within the network, when using the spherical or the linear semivariograms models were between 10% and 13% of the mean irradiation for daily irradiation and between 12% and 20% for hourly irradiation. These errors represent an improvement of 1%-2% when compared with replacing data at a given site with the data of the nearest weather station.

Merino, G. G.; Jones, D.; Stooksbury, D. E.; Hubbard, K. G.

2001-06-01

388

Model Studies of Solar Spectral Irradiance at the Bottom and Top of a Cloudy Atmosphere  

NASA Astrophysics Data System (ADS)

This dissertation describes the development and testing of a spectral model for transmission of solar radiation through a cloudy atmosphere. Clear-sky effects include absorption by ozone, water vapor, the uniformly-mixed gases and aerosols; and scattering by air molecules (Rayleigh scattering) and aerosols. These optical effects are treated with a Beer's Law relationship using extinction coefficients for each of 145 spectral intervals from 0.29 to 4.0 (mu)m. Cloud optical effects are treated with the delta-Eddington approximation. The model calculates spectral irradiances at the surface and the top of the atmosphere. The model is tested against 221 hours of broad-band and spectral (> 630 nm) irradiances measured at the Georgia Tech Solar Energy Meteorological Research and Training Site. Upward irradiances at the top of the atmosphere are converted into directional radiances through empirical bidirectional reflectance factors and the resulting radiances are compared against radiances for 168 hours measured by satellite at the same time and at the same hours measured by satellite at the same time and at the same location. The model reproduces measured surface irradiances with a root-mean-square error of 11.7% of the model mean. The directional reflectances have an rms error of 16.4% of the model mean; when nine outlying points are removed from the data, the remaining data have an rms error of 12.5% of the mean. Testing of the model indicates that it has sufficient accuracy for such purposes as calibration of satellite sensors in the visible spectrum.

Paris, Mark Vaughan

389

Assessing the relationship between spectral solar irradiance and stratospheric ozone using Bayesian inference  

E-print Network

We investigate the relationship between spectral solar irradiance (SSI) and ozone in the tropical upper stratosphere. We find that solar cycle (SC) changes in ozone can be well approximated by considering the ozone response to SSI changes in a small number individual wavelength bands between 176 and 310 nm, operating independently of each other. Additionally, we find that the ozone varies approximately linearly with changes in the SSI. Using these facts, we present a Bayesian formalism for inferring SC SSI changes and uncertainties from measured SC ozone profiles. Bayesian inference is a powerful, mathematically self-consistent method of considering both the uncertainties of the data and additional external information to provide the best estimate of parameters being estimated. Using this method, we show that, given measurement uncertainties in both ozone and SSI datasets, it is not currently possible to distinguish between observed or modelled SSI datasets using available estimates of ozone change profiles, ...

Ball, William T; Egerton, Jack S; Haigh, Joanna D

2014-01-01

390

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

391

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.

392

The Discrepancy Between Measured and Modeled Downwelling Solar Irradiance at the Ground: Dependence on Water Vapor  

NASA Technical Reports Server (NTRS)

Moderate resolution spectra of the downwelling solar irradiance at the ground in north central Oklahoma were measured during the Department of Energy Atmospheric Radiation Measurement Program Intensive Observation Period in the fall of 1997. Spectra obtained under-cloud-free conditions were compared with calculations using a coarse resolution radiative transfer model to examine the dependency of model-measurement bias on water vapor. It was found that the bias was highly correlated with water vapor and increased at a rate of 9 Wm per cm of water. The source of the discrepancy remains undetermined because of the complex dependencies of other variables, most notably aerosol optical depth, on water vapor.

Pilewski, P.; Rabbette, M.; Bergstrom, R.; Marquez, J.; Schmid, B.; Russell, P. B.

2000-01-01

393

Azo-dyes photocatalytic degradation in aqueous suspension of TiO 2 under solar irradiation  

Microsoft Academic Search

The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almer??a” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs

Vincenzo Augugliaro; Claudio Baiocchi; Alessandra Bianco Prevot; Elisa Garc??a-López; Vittorio Loddo; Sixto Malato; Giuseppe Marc??; Leonardo Palmisano; Marco Pazzi; Edmondo Pramauro

2002-01-01

394

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

395

Extremophiles and the Search for Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

Extremophiles thrive in ice, boiling water, acid, the water core of nuclear reactors, salt crystals, and toxic waste and in a range of other extreme habitats that were previously thought to be inhospitable for life. Extremophiles include representatives of all three domains (Bacteria, Archaea, and Eucarya); however, the majority are microorganisms, and a high proportion of these are Archaea. Knowledge of extremophile habitats is expanding the number and types of extraterrestrial locations that may be targeted for exploration. In addition, contemporary biological studies are being fueled by the increasing availability of genome sequences and associated functional studies of extremophiles. This is leading to the identification of new biomarkers, an accurate assessment of cellular evolution, insight into the ability of microorganisms to survive in meteorites and during periods of global extinction, and knowledge of how to process and examine environmental samples to detect viable life forms. This paper evaluates extremophiles and extreme environments in the context of astrobiology and the search for extraterrestrial life.

Cavicchioli, Ricardo

2002-08-01

396

SOVAP/ Picard, a Spaceborne Radiometer to Measure the Total Solar Irradiance  

NASA Astrophysics Data System (ADS)

The Picard spacecraft was successfully launched on 15 June 2010, into a Sun-synchronous orbit. The mission represents one of the European contributions to solar observations and Essential Climate Variables (ECVs) measurements. The payload is composed of a Solar Diameter Imager and Surface Mapper (SODISM) and two radiometers: SOlar VAriability Picard (SOVAP) and PREcision MOnitor Sensor (PREMOS). SOVAP, a dual side-by-side cavity radiometer, measures the total solar irradiance (TSI). It is the sixth of a series of differential absolute-radiometer-type instruments developed and operated in space by the Royal Meteorological Institute of Belgium. The measurements of SOVAP in the summer of 2010 yielded a TSI value of 1362.1 W m-2 with an uncertainty of ± 2.4 W m-2 ( k=1). During the periods of November 2010 and January 2013, the amplitude of the changes in TSI has been on the order of 0.18 %, corresponding to a range of about 2.4 W m-2.

Meftah, M.; Dewitte, S.; Irbah, A.; Chevalier, A.; Conscience, C.; Crommelynck, D.; Janssen, E.; Mekaoui, S.

2014-05-01

397

Prediction and measurement of direct-normal solar irradiance: A closure experiment  

NASA Technical Reports Server (NTRS)

Direct-Normal Solar Irradiance (DNSI), the total energy in the solar spectrum incident on a plane perpendicular to the Sun's direction on a unit area at the earth's surface in unit time, depends only on the atmospheric extinction of sunlight without regard to the details of extinction-whether absorption or scattering. Here the authors describe a set of closure experiments performed in north-central Oklahoma, wherein measured atmospheric composition is input to a radiative transfer model, MODTRAN-3, to predict DNSI, which is then compared to measured values. Thirty six independent comparisons are presented; the agreement between predicted and measured values falls within the combined uncertainties in the prediction (2%) and measurement (0.2%) albeit with a slight bias ((approximately) 1% overprediction) that is independent of the solar zenith angle. Thus these results establish the adequacy of current knowledge of the solar spectrum and atmospheric extinction as embodied in MODTRAN-3 for use in climate models. An important consequence is the overwhelming likelihood that the atmospheric clear-sky absorption is accurately described to within comparable uncertainties.

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

1997-01-01

398

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 d...

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

2013-01-01

399

Multiscale comparative spectral analysis of satellite total solar irradiance measurements from 2003 to 2013 reveals a planetary modulation of solar activity and its nonlinear dependence on the 11 yr solar cycle  

NASA Astrophysics Data System (ADS)

Herein we adopt a multiscale dynamical spectral analysis technique to compare and study the dynamical evolution of the harmonic components of the overlapping ACRIMSAT/ACRIM3 (Active Cavity Radiometer Irradiance Monitor Satellite/Active Cavity Radiometer Irradiance Monitor 3), SOHO/VIRGO (Solar and Heliopheric Observatory/Variability of solar Irradiance and Gravity Oscillations), and SORCE/TIM (Solar Radiation and Climate Experiment/Total Irradiance Monitor) total solar irradiance (TSI) records during 2003.15 to 2013.16 in solar cycles 23 and 24. The three TSI time series present highly correlated patterns. Significant power spectral peaks are common to these records and are observed at the following periods: ~ 0.070 yr, ~ 0.097 yr, ~ 0.20 yr, ~ 0.25 yr, ~ 0.30-0.34 yr, and ~ 0.39 yr. Less certain spectral peaks occur at about 0.55 yr, 0.60-0.65 yr and 0.7-0.9 yr. Four main frequency periods at ~ 4.8 days (~ 0.068 yr), ~ 27.3 days (~ 0.075 yr), at ~ 34-35 days (~ 0.093-0.096 yr), and ~ 36-38 days (~ 0.099-0.104 yr) characterize the solar rotation cycle. The amplitude of these oscillations, in particular of those with periods larger than 0.5 yr, appears to be modulated by the ~ 11 yr solar cycle. Similar harmonics have been found in other solar indices. The observed periodicities are found highly coherent with the spring, orbital and synodic periods of Mercury, Venus, Earth and Jupiter. We conclude that solar activity is likely modulated by planetary gravitational and electromagnetic forces acting on the Sun. The strength of the Sun's response to planetary forcing depends nonlinearly on the state of internal solar dynamics; planetary-Sun coupling effects are enhanced during solar activity maxima and attenuated during minima.

Scafetta, N.; Willson, R. C.

2013-11-01

400

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

401

Paleoindian demography and the extraterrestrial impact hypothesis  

PubMed Central

Recently it has been suggested that one or more large extraterrestrial (ET) objects struck northern North America 12,900 ± 100 calendar years before present (calBP) [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104: 16016–16021]. This impact is claimed to have triggered the Younger Dryas major cooling event and resulted in the extinction of the North American megafauna. The impact is also claimed to have caused major cultural changes and population decline among the Paleoindians. Here, we report a study in which ?1,500 radiocarbon dates from archaeological sites in Canada and the United States were used to test the hypothesis that the ET resulted in population decline among the Paleoindians. Following recent studies [e.g., Gamble C, Davies W, Pettitt P, Hazelwood L, Richards M (2005) Camb Archaeol J 15:193–223), the summed probability distribution of the calibrated dates was used to identify probable changes in human population size between 15,000 and 9,000 calBP. Subsequently, potential biases were evaluated by modeling and spatial analysis of the dated occupations. The results of the analyses were not consistent with the predictions of extraterrestrial impact hypothesis. No evidence of a population decline among the Paleoindians at 12,900 ± 100 calBP was found. Thus, minimally, the study suggests the extraterrestrial impact hypothesis should be amended. PMID:18697936

Buchanan, Briggs; Collard, Mark; Edinborough, Kevan

2008-01-01

402

Siderophilic Cyanobacteria for the Development of Extraterrestrial Photoautotrophic Biotechnologies  

NASA Technical Reports Server (NTRS)

In-situ production of consumables (mainly oxygen) using local resources (In-Situ Resource Utilization-ISRU) will significantly facilitate current plans for human exploration and settlement of the solar system, starting with the Moon. With few exceptions, nearly all technologies developed to date have employed an approach based on inorganic chemistry. None of these technologies include concepts for integrating the ISRU system with a bioregenerative life support system and a food production system. Therefore, a new concept based on the cultivation of cyanobacteria (CB) in semi-closed biogeoreactor, linking ISRU, a biological life support system, and food production, has been proposed. The key feature of the biogeoreactor is to use lithotrophic CB to extract many needed elements such as Fe directly from the dissolved regolith and direct them to any technological loop at an extraterrestrial outpost. Our studies showed that siderophilic (Fe-loving) CB are capable to corrode lunar regolith stimulants because they secrete chelating agents and can tolerate [Fe] up to 1 mM. However, lunar and Martian environments are very hostile (very high UV and gamma-radiation, extreme temperatures, deficit of water). Thus, the selection of CB species with high potential for extraterrestrial biotechnologies that may be utilized in 15 years must be sponsored by NASA as soon as possible. The study of the genomes of candidate CB species and the metagenomes of the terrestrial environments which they inhabit is critical to make this decision. Here we provide preliminary results about peculiarities of the genomes of siderophilic CB revealed by analyzing the genome of siderophilic cyanobacterium JSC-1 and the metagenome of iron depositing hot spring (IDHS) Chocolate Pots (Yellowstone National Park, Wyoming, USA). It has been found that IDHS are richer with ferrous iron than the majority of hot springs around the world. Fe2+ is known to increase the magnitude of oxidative stress in prokaryotes through so called Fenton reaction. It is not surprising therefore that the CB inhabiting IDHS have larger sets of the proteins involved in the maintenance of Fe homeostasis and oxidative stress protection than non-siderophilic CB. This finding combined with our earlier results about the ability of some siderophilic CB to utilize chemical elements released from analogs of lunar and Martian regolith make them the most advanced candidates to be employed in advanced extraterrestrial biotechnologies.

Brown, I. I.; McKay, D. S.

2010-01-01

403

Euhedral metallic-Fe-Ni grains in extraterrestrial samples  

NASA Technical Reports Server (NTRS)

Metallic Fe-Ni is rare in terrestrial rocks, being largely restricted to serpentinized peridotites and volcanic rocks that assimilated carbonaceous material. In contrast, metallic Fe-Ni is nearly ubiquitous among extraterrestrial samples (i.e., meteorites, lunar rocks, and interplanetary dust particles). Anhedral grains are common. For example, in eucrites and lunar basalts, most of the metallic Fe-Ni occurs interstitially between silicate grains and thus tends to have irregular morphologies. In many porphyritic chondrules, metallic Fe-Ni and troilite form rounded blebs in the mesostasis because their precursors were immiscible droplets. In metamorphosed ordinary chondrites, metallic Fe-Ni and troilite form coarse anhedral grains. Some of the metallic Fe-Ni and troilite grains has also been mobilized and injected into fractures in adjacent silicate grains where local shock-reheating temperatures reached the Fe-FeS eutectic (988 C). In interplanetary dust particles metallic Fe-Ni most commonly occurs along with sulfide as spheroids and fragments. Euhedral metallic Fe-Ni grains are extremely rare. Several conditions must be met before such grains can form: (1) grain growth must occur at free surfaces, restricting euhedral metallic Fe-Ni grains to systems that are igneous or undergoing vapor-deposition; (2) the metal (+/-) sulfide assemblage must have an appropriate bulk composition so that taenite is the liquidus phase in igneous systems or the stable condensate phase in vapor-deposition systems; and (3) metallic Fe-Ni grains must remain underformed during subsequent compaction, thermal metamorphism, and shock. Because of these restrictions, the occurrence of euhedral metallic Fe-Ni grains in an object can potentially provide important petrogenetic information. Despite its rarity, euhedral metallic Fe-Ni occurs in a wide variety of extraterrestrial materials. Some of these materials formed in the solar nebula; others formed on parent body surfaces by meteoroid impacts.

Rubin, Alan E.

1993-01-01

404

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

405

Decoupling the effects of clear atmosphere and clouds to simplify calculations of the broadband solar irradiance at ground level  

NASA Astrophysics Data System (ADS)

In the case of infinite plane-parallel single- and double-layered cloud, the solar irradiance at ground level computed by a radiative transfer model can be approximated by the product of the irradiance under clear atmosphere and a modification factor due to cloud properties and ground albedo only. Changes in clear-atmosphere properties have negligible effect on the latter so that both terms can be calculated independently. The error made in using this approximation depends mostly on the solar zenith angle, the ground albedo and the cloud optical depth. In most cases, the maximum errors (95th percentile) on global and direct surface irradiances are less than 15 W m-2 and less than 2-5% in relative value. These values are similar to those recommended by the World Meteorological Organization for high-quality measurements of the solar irradiance. Practically, the results mean that a model for fast calculation of surface solar irradiance may be separated into two distinct and independent models, possibly abacus-based, whose input parameters and resolutions can be different, and whose creation requires less computation time and resources than a single model.

Oumbe, A.; Qu, Z.; Blanc, P.; Lefèvre, M.; Wald, L.; Cros, S.

2014-08-01

406

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

407

Analysis of the total solar irradiance composite and their contribution to global mean air surface temperature rise  

NASA Astrophysics Data System (ADS)

Herein I discuss and propose updated satellite composites of the total solar irradiance covering the period 1978-2008. The composites are compiled from measurements made with the three ACRIM experiments. Measurements from the NIMBUS7/ERB, the ERBS/ERBE satellite experiments and a total solar irradiance proxy reconstruction are used to fill the gap from June 1989 to October 1991 between ACRIM1 and ACRIM2 experiments. The result of the analysis does suggests that the total solar irradiance did increase from 1980 to 2002. The climate implications of the alternative satellite composites are discussed by using a phenomenological climate model which depends on two characteristics time response at tau1 =0.4 year and tau2=8-12 years, as determined phenomenologically [Scafetta, JGR 2008]. Reconstructions of total solar irradiance signature on climate during the last four centuries are discussed. The solar variability appears to have significantly contributed to climate change during the last four centuries, including the last century. Indirectly, the model suggests that the preindustrial climate experienced a large variability which is incompatible with an Hockey Stick temperature graph.

Scafetta, N.

2008-12-01

408

Field measurement of clear-sky solar irradiance in Badain Jaran Desert of Northwestern China  

NASA Astrophysics Data System (ADS)

The Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) sponsored and conducted an intensive field campaign on dust aerosols in Badain Jaran Desert of Northwestern China from April 20 to June 20, 2010. A set of state-of-the-art broadband radiometers and sun/sky photometers were deployed along with launched radiosonde. In this paper, we compared the simulated solar irradiances by using the SBDART radiative transfer model with those from the ground-based measurements for 69 selected cases of 7 days. It was shown that the averaged aerosol optical depth at 500nm (AOD500) is 0.18±0.09 with AOD500 less than 0.5 for all cases. The single-scattering albedo and asymmetry factor at 675nm are 0.928±0.035, 0.712±0.023, respectively. The AODs retrieved from the CIMEL sun photometer at various wavelengths agree well with those from the PREDE sky radiometer, and the columnar water vapor contents from CIMEL also agree well with radiosonde observations. In the radiative closure experiment, we used a collocated thermopile pyrgeometer with a shadow and ventilator to correct the thermal dome offset of diffuse irradiance measurement. The mean differences between model and measurements are -9.1Wm-2 (-2.6%) for the direct irradiance, +3.1Wm-2 (+2.8%) for diffuse irradiance, and -6.0Wm-2 (-1.3%) for global irradiance, which indicates an excellent radiative closure. Aerosol shortwave direct radiative forcing (ARF) and radiative heating rate are also investigated. The daily mean ARF ranges from -4.8 to +0.4Wm-2 at the top of the atmosphere, -5.2 to -15.6Wm-2 at the surface, and 5.2 to 10.8Wm-2 in the atmosphere. The corresponding radiative heating rates for the whole atmosphere due to dust aerosols are 0.07, 0.11, 0.14, 0.11, 0.10, 0.08, and 0.07K/day for the 7 selected cloudless days. These solar radiative forcing can be considered as the representative impact of background dust aerosol in Northwestern China.

Bi, Jianrong; Huang, Jianping; Fu, Qiang; Ge, Jinming; Shi, Jinsen; Zhou, Tian; Zhang, Wu

2013-06-01

409

The Twentieth Century History of the Extraterrestrial Life Debate: Major Themes and Lessons Learned  

NASA Astrophysics Data System (ADS)

In this chapter we provide an overview of the extraterrestrial life debate since 1900, drawing largely on the major histories of the subject during this period, The Biological Universe (Dick 1996), Life on Other Worlds (Dick 1998), and The Living Universe (Dick and Strick 2004), as well as other published work. We outline the major components of the debate, including (1) the role of planetary science, (2) the search for planets beyond the solar system, (3) research on the origins of life, and (4) the Search for Extraterrestrial Intelligence (SETI). We emphasize the discovery of cosmic evolution as the proper context for the debate, reserving the cultural implications of astrobiology for part III of this volume. We conclude with possible lessons learned from this history, especially in the domains of the problematic nature of evidence, inference, and metaphysical preconceptions; the checkered role of theory; and an analysis of how representative general current arguments have fared in the past.

Dick, Steven J.

410

Influence of solar UV irradiance on the quasi-biennial oscillation of zonal winds in the equatorial stratosphere  

Microsoft Academic Search

The vertical wind profiles in the equatorial stratosphere for 1953–2005 have been examined in relation to variations of solar F10.7 index to reveal influence of solar UV irradiance on the quasi-biennial oscillation (QBO) of zonal winds. Previously it was shown (Gabis, I.P., Troshichev, O.A., 2005. QBO cycle identified by changes in height profile of the zonal winds: new regularities. Journal

I. Gabis; O. Troshichev

2006-01-01

411

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

412

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

413

ACRIMSAT/ACRIM3 Recalibration and the Total Solar Irradiance Database  

NASA Astrophysics Data System (ADS)

The ACRIMSAT/ACRIM3 flight backup instrument was characterized at the LASP/TRF facility for calibration of satellite total solar irradiance (TSI) sensors. The TRF approach provides a NIST SI scale reference and characterization of the effects of scattering and diffraction using a cryogenic pyrheliometer and a laser transfer system. Agreement with the radiation standard maintained by NIST was found to be within the uncertainty of the measurements but a significant correction of - 0.5 % 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. This correction, along with algorithm updates for instrument thermal behavior and sensor degradation, provide ACRIM3 results with state of the art accuracy and precision. Comparison of the results of all three currently operational satellite TSI monitoring experiments provides new insights into the variability of TSI and reduces the uncertainty of the 34 year satellite TSI time series. A new solar magnetic activity area proxy has been used to demonstrate that the ACRIM TSI composite and its + 0.04 %/decade TSI trend during solar cycles 21 - 23 is the most likely correct representation of the extant satellite TSI database.

Willson, R. C.

2013-12-01

414

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

415

Accuracy and sensitivity analysis for 54 models of computing hourly diffuse solar irradiation on clear sky  

NASA Astrophysics Data System (ADS)

Fifty-four broadband models for computation of solar diffuse irradiation on horizontal surface were tested in Romania (South-Eastern Europe). The input data consist of surface meteorological data, column integrated data, and data derived from satellite measurements. The testing procedure is performed in 21 stages intended to provide information about the sensitivity of the models to various sets of input data. There is no model to be ranked "the best" for all sets of input data. However, some of the models performed better than others, in the sense that they were ranked among the best for most of the testing stages. The best models for solar diffuse radiation computation are, on equal footing, ASHRAE 2005 model (ASHRAE 2005) and King model (King and Buckius, Solar Energy 22:297-301, 1979). The second best model is MAC model (Davies, Bound Layer Meteor 9:33-52, 1975). Details about the performance of each model in the 21 testing stages are found in the Electronic Supplementary Material.

Badescu, Viorel; Gueymard, Christian A.; Cheval, Sorin; Oprea, Cristian; Baciu, Madalina; Dumitrescu, Alexandru; Iacobescu, Flavius; Milos, Ioan; Rada, Costel

2013-02-01

416

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

417

Middle atmosphere heating rate and photolysis response to the uncertainties in spectral solar irradiance data  

NASA Astrophysics Data System (ADS)

Solar radiation is the main source of energy for the Earth’s atmosphere and in many respects defines its composition, photochemistry, temperature profile and dynamics. Therefore, the uncertainties in the magnitude and spectral composition of the spectral solar irradiance (SSI) evolution during the declining phase of 23rd solar cycle have substantial implications for the modeling of the middle atmosphere evolution, leading to a pronounced differences in the heating rates and also affecting photolysis rates. To estimate the role of SSI uncertainties we have compared the most important photolysis rates (O2, O3, and NO2) and heating rates calculated with the reference radiation code libRadtran using SSI for June 2004 and February 2009 obtained from two models (NRL, COSI) and one observation data set based on SORCE observations. We have also evaluated the ability of the several photolysis and heating rates calculation methods widely used in atmospheric models to reproduce the absolute values of the photolysis rates and their response to the implied SSI changes.

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

418

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

419

Algorithmic communication with extraterrestrial intelligence (ACETI)  

NASA Astrophysics Data System (ADS)

Many different strategies for communication with extraterrestrial intelligence have been proposed since the invention of wireless communication. these strategies can be roughly divided into two categories: pictorial and non- pictorial (math-based) systems. Pictorial messages, such as the bitmap transmitted from the Arecibo radiotelescope in 1975, can be used to communicate a wide variety of ideas and symbols. Non-pictorial systems, such as Hans Freudenthal's language Lingua Cosmica (Lincos), allow the sender to build a symbolic vocabulary without the use of pixelated images.

McConnell, Brian

2001-08-01

420

Space nuclear power systems for extraterrestrial basing  

NASA Technical Reports Server (NTRS)

Comparative analyses reveal that the nuclear power option significantly reduces the logistic burden required to support a lunar base. The paper considers power levels from tens of kWe for early base operation up to 2000 kWe for a self-sustaining base with a CELSS. It is shown that SP-100 and NERVA derivative reactor (NDR) technology for space power can be used effectively for extraterrestrial base power systems. Recent developments in NDR design that result in major reductions in reactor mass are described.

Lance, J. R.; Chi, J. W. H.

1989-01-01