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1

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

Microsoft Academic Search

The extraterrestrial solar spectrum between 295 and 355 nm has been determined from direct irradiance measurements made with a Brewer double spectrophotometer, using the Langley method. The measurements in this study consist of 449 half days of data collected during 1998 at Mauna Loa Observatory, Hawaii. The +\\/-2.3% accuracy of this extraterrestrial solar spectrum is obtained by a careful investigation

J. Gröbner; J. B. Kerr

2001-01-01

2

Extraterrestrial Solar Neutrino Physics  

E-print Network

We advocate the extraterrestrial solar neutrino physics (etSNP) as a means of investigating solar neutrino physics (SNP). As we already know, the dominant and subdominant (vacuum) oscillation lengths would be approximately one kilometer and one hundred kilometers. On the other hand, we know so far that the matter-enhanced oscillations take place only in the core of the Sun. Thus, the etSNP, i.e. solar neutrino physics that could be extracted outside the Earth, would assume a special unique role. The etSNP experiments include (1) a satellite (detector) around the Earth or around the Jupiter or others (to provide the shadow, for the matter-enhanced neutrino oscillations), (2) during the Sun-Venus-Earth eclipse or similar, and (3) the chemical compositions of the geology type (as in the Jupiter or in the Venus, to study the origins of these planets). To be specific, we note that the reactions induced by the ^8B solar neutrinos, in view of the sole high energy nature (E_\

W-Y. Pauchy Hwang; Jen-Chieh Peng

2010-03-23

3

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

4

Calibration of EOS multispectral imaging sensors and solar irradiance variability  

NASA Technical Reports Server (NTRS)

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

Mecherikunnel, Ann

1991-01-01

5

Extraterrestrial applications of solar optics for interior illumination  

NASA Technical Reports Server (NTRS)

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

Eijadi, David A.; Williams, Kyle D.

1992-01-01

6

The effect of chosen extraterrestrial solar spectrum on clear-sky atmospheric absorption and heating rates in the near infrared  

NASA Astrophysics Data System (ADS)

The extraterrestrial solar spectrum (ESS) is an important component in near infrared (near-IR) radiative transfer calculations. However, the impact of a particular choice of the ESS in these regions has been given very little attention. A line-by-line (LBL) transfer model has been used to calculate the absorbed solar irradiance and solar heating rates in the near-IR from 2000-10000 cm-1(1-5 ?m) using different ESS. For overhead sun conditions in a mid-latitude summer atmosphere, the absorbed irradiances could differ by up to about 11 Wm-2 (8.2%) while the tropospheric and stratospheric heating rates could differ by up to about 0.13 K day-1 (8.1%) and 0.19 K day-1 (7.6%). The spectral shape of the ESS also has a small but non-negligible impact on these factors in the near-IR.

Menang, Kaah P.; Shine, Keith P.

2013-05-01

7

Laboratory Study of Extraterrestrial Ices Electrical Properties and Interaction with Irradiation  

NASA Astrophysics Data System (ADS)

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

Shi, Jianming

8

Relationship between diffuse, total, and extraterrestrial solar radiation  

Microsoft Academic Search

A method of approximating diffuse beam solar radiation is extended to the upper middle latitudes through the use of several years of mean monthly data and one year of daily data recorded at four stations in Canada which represent a variety of climatic regions as well as both highly urbanized and remote localities. (WDM)

S TULLER

1976-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

10

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

NASA Technical Reports Server (NTRS)

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

Reedy, Robert C.

1999-01-01

11

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

NASA Technical Reports Server (NTRS)

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

Reedy, Robert C.

2000-01-01

12

Modeling monthly mean variation of the solar global irradiation  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

13

Observations of solar irradiance variability  

NASA Technical Reports Server (NTRS)

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 0.01%. Irradiance fluctuations are typical of a band-limited noise spectrum with high-frequency cutoff near 0.15/day; their amplitudes about the mean value of 1368.31 watts per square meter approach plus or minus 0.05%. Two large decreases in irradiance of up to 0.2% lasting about one week are highly correlated with the development of sunspot groups. The magnitude and time scale of the irradiance variability suggest that considerable energy storage occurs within the convection zone in solar active regions.

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

1981-01-01

14

Laser power and solar irradiance  

Microsoft Academic Search

This paper presents experience with two accurate and stable detectors of optical radiation: a Scientech disk calorimeter used as a standard for laser power measurement and a Kendall radiometer system (Technical Measurements, Inc.) used as a standard for solar irradiance measurements. The construction, calibration, and maintenance of each detector are first presented both for general interest and to contrast one

P. D. Thacher

1977-01-01

15

On the depth-dependent production of radionuclides (44?A?59) by solar protons in extraterrestrial matter  

Microsoft Academic Search

In order to interpret cosmogenic radionuclides in extraterrestrial matter one has to differentiate between p- and ?-induced\\u000a reactions with solar (SCR) and with galactic (GCR) cosmic rays. Our earlier studies have shown that for a satisfactory description\\u000a of GCR-interactions with dense matter rather few but characteristic high energy cross sections are required. In contrast,\\u000a for the low and medium energy

R. Michel; G. Brinkmann

1980-01-01

16

Total solar irradiance during the Holocene  

Microsoft Academic Search

For the first time a record of total 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 and the open solar magnetic field. Here we show that the open solar magnetic field can be obtained from the cosmogenic radionuclide 10Be measured in

F. Steinhilber; J. Beer; C. Fröhlich

2009-01-01

17

SORCE Solar Irradiance Data Products  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

18

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

19

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

20

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

21

Reconstruction of solar UV irradiance since 1974  

Microsoft Academic Search

Variations of the solar UV irradiance are an important driver of chemical and physical processes in the Earth's upper atmosphere and may also influence global climate. Here we reconstruct solar UV irradiance in the range 115–400 nm over the period 1974–2007 by making use of the recently developed empirical extension of the Spectral And Total Irradiance Reconstruction (SATIRE) models employing

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

2009-01-01

22

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-scaling capacities of renewable energy sources such as wind and solar. However, variability and uncertainty in power

Cerpa, Alberto E.

23

Calculation of Solar Irradiances. I. Synthesis of the Solar Spectrum  

Microsoft Academic Search

Variations in the total radiative output of the Sun as well as the detailed spectral irradiance are of interest to terrestrial and solar-stellar atmosphere studies. Recent observations provide measurements of spectral irradiance variations at wavelengths in the range 1100-8650 Å with improved accuracy, and correlative studies give procedures for estimating the spectral irradiance changes from solar activity records using indicators

Juan Fontenla; Oran R. White; Peter A. Fox; Eugene H. Avrett; Robert L. Kurucz

1999-01-01

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

Studying Solar Irradiance Variability with Wavelet Technique  

NASA Technical Reports Server (NTRS)

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

Vigouroux, Anne; Pap, Judit

1995-01-01

26

Total Solar Irradiance Satellite Composites and their  

E-print Network

Chapter 12 Total Solar Irradiance Satellite Composites and their Phenomenological Effect on Climate. Phenomenological solar signature on climate 310 9. Conclusion 312 1. INTRODUCTION A contiguoustotal solar from each other, in particular about whether the TSI minimum during solar Cycles 22e23 (1995

Scafetta, Nicola

27

Solar spectral irradiance and total solar irradiance at a solar minimum  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

28

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

29

Solar Irradiance Variations Measured from Spacecraft  

NASA Astrophysics Data System (ADS)

As the solar energy flux is deposited in various parts of the Earth's atmosphere, oceans, and land, it controls the heating, ionization, radiative, chemical, and dynamical processes characterizing the terrestrial atmosphere and climate system. Therefore, the accurate knowledge of the solar energy received by Earth and understanding its variability are critical issues for an understanding of the climate response to the increasing greenhouse gas concentrations. Solar irradiance (both bolometric and at UV wavelengths) has been measured continuously from various space platforms since late 1978. These irradiance measurements established conclusively that solar irradiance varies on time scales from minutes to decades. The most important discovery of the space-based irradiance measurements is that total irradiance varies with about 0.1% over the solar cycle, being higher during maximum activity conditions. Since even small variations in total irradiance over long time scales may lead to climate changes, it is extremely important (1) to maintain a long-term high precision irradiance data base for climate studies and (2) to understand the underlying physical mechanisms. In this paper we summarize the results gained from the multi-decade long space-based irradiance measurements. This research was supported by a grant NAG5-10876 from the SOHO Office of NASA's Office of Space Science and by NASA grants NAG5-9207 and NAG5-11326 from NASA's Office of Earth Science. SOHO is a mission of international cooperation between ESA and NASA.

Pap, J. M.

2001-12-01

30

Variability of Solar Irradiances Using Wavelet Analysis  

NASA Technical Reports Server (NTRS)

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

Pesnell, William D.

2007-01-01

31

Extraterrestrial Samples at JSC  

NASA Technical Reports Server (NTRS)

A viewgraph presentation on the curation of extraterrestrial samples at NASA Johnson Space Center is shown. The topics include: 1) Apollo lunar samples; 2) Meteorites from Antarctica; 3) Cosmic dust from the stratosphere; 4) Genesis solar wind ions; 5) Stardust comet and interstellar grains; and 5) Space-Exposed Hardware.

Allen, Carlton C.

2007-01-01

32

Reconstruction of solar UV irradiance since 1974  

Microsoft Academic Search

Variations of the solar UV irradiance are an important driver of chemical and\\u000aphysical processes in the Earth's upper atmosphere and may also influence\\u000aglobal climate. Here we reconstruct solar UV irradiance in the range 115-400 nm\\u000aover the period 1974-2007 by making use of the recently developed empirical\\u000aextension of the SATIRE models employing SUSIM data. The evolution of

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

2009-01-01

33

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.

34

Extraterrestrial Water  

NASA Astrophysics Data System (ADS)

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 Europa both probably have subsurface water. Researchers from NASA and elsewhere are hoping to eventually probe these subsurface reservoirs and determine whether life exists there. A more promising venue for finding extraterrestrial life is on Earth-like planets around other stars. Such planets can in principle be located and analyzed spectroscopically using large space-based telescopes like NASA's proposed Terrestrial Planet Finder (TPF) Mission (1). The chances of success for this mission depend critically on the abundance of Earth-like planets with liquid water at their surfaces because only there could a biota exist that would be widespread enough to modify the planet's atmosphere in a way that would be detectable. Models of planetary accretion suggest that most terrestrial planets should be endowed with substantial amounts of water (2). Climate models suggest that the "habitable zone" around solar-type stars is relatively wide so that water can remain liquid on a planet's surface for long times (3). Thus, the chances of finding water, and maybe life, elsewhere appear to be good. References: (1) Beichman, C. A., Woolf, N. J. and Lindensmith, C. A. The Terrestrial Planet Finder (TPF): A NASA Origins Program to Search for Habitable Planets (JPL Publication 99-3) (NASA Jet Propulsion Laboratory, Pasadena, CA, 1999). (2) Morbidelli, A., Chambers, J., Lunine, J. I., Petit, J. M., Robert, F., Valsecchi, G. B. and Cyr, K. E. Meteoritics and Planet. Sci. 35, 1309-1320 (2000). (3) Kasting, J. F., Whitmire, D. P. and Reynolds, R. T. Icarus 101, 108-128 (1993).

Kasting, J. F.

2002-12-01

35

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

36

Magnetic Modulation of Solar 304 Å Irradiance  

NASA Astrophysics Data System (ADS)

Solar 304 Å irradiance is an important source of heating and ionization in the Earth's upper atmosphere. Because only intermittent observations exist prior to solar cycle 23, the absolute levels and solar cycle variability of 304 Å irradiance are uncertain by a factor of two, based on the range of estimates from four current EUV irradiance variability models. Large active regions are a significant source of 304 Å radiation but their characteristics are not well specified, with contrasts reported in the range of two to ten. Statistical quantification of the role of small scale active regions and network is also lacking. During solar cycle 23, three different instruments are observing the Sun's 304 Å radiation concurrently. The EIT on SOHO records the brightness distribution on the solar disk in a 20 Å band, SEM on SOHO monitors the disk-integrated emission in an 80 Å band, and the SEE grating spectrometer on the TIMED spacecraft recently began observing EUV irradiance spectra with 4 Å resolution. We calculate daily histograms of the brightness distributions of EIT images after adjustments for various instrumental effects. Deconstructions of the histograms permit statistical characterizations of magnetic sources of 304 Å irradiance variability during solar cycle 23, in terms of fractional disk areas and contrasts. We also study center-to-limb variations. The calculations provide independent irradiance variability estimates for comparison with the SEM and SEE direct irradiance observations, and the models. We utilize the source characterizations to revise the NRLEUV model, the present version of which estimates 304 Å emission by assuming that a bright active region has a contrast of ten, and that source region evolution is temporally similar to the Mg chromospheric irradiance index. Funded by NASA SEC GI Program.

Lean, J. L.; Mariska, J. T.; Warren, H. P.; Woods, T. N.; Eparvier, F. G.; McMullin, D. R.; Judge, D. L.; Newmark, J. S.; Viereck, R. A.

2003-05-01

37

Extraterrestrial imperative  

NASA Technical Reports Server (NTRS)

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

Ehricke, K. A.

1972-01-01

38

Spallation reactions in extraterrestrial matter  

SciTech Connect

This paper describes the cosmic-ray-induced production of stable and radioactive residual nuclides, the so-called cosmogenic nuclides. In extraterrestrial solar-system matter, i.e. planetary surfaces, meteorites, cosmic dust and the heavy component of the galactic cosmic radiation, these nuclides are experimentally observable as positive anomalies of isotopic abundances. They preserve a record of cosmic ray exposure which can be interpreted with respect to the collision and exposure history of the irradiated objects as well as to intensities and spectral distributions of cosmic ray particles in the past. To decipher the cosmic ray record in extraterrestrial matter and to obtain information which cannot be obtained by any other means reliable models are needed for the calculation of the production rates of cosmogenic nuclides. On the basis of thin-target and thick-target accelerator experiments such a model has been developed which is applied here exemplarily to interprete cosmogenic nuclide abundances in stony meteorites and lunar surface materials.

Michel, Rolf [Zentrum fuer Strahlenschutz und Radiooekologie, Universitaet Hannover, Am Kleinen Felde 30, D-30167 Hannover (Germany)

1998-02-15

39

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

40

Earth Radiation Budget Satellite extraterrestrial solar constant measurements - 1986-1987 increasing trend  

NASA Technical Reports Server (NTRS)

From June 1986 through Nov 1987, the Earth Radiation Budget Satellite (ERBS) pyrheliometric measurements indicated that the solar constant was increasing approximately +0.02 percent per year. Earlier ERBS measurements indicated that the solar constant was declining approximately -0.03 percent per year during the 1984 through mid-1986 period. Since mid-1986 represents the beginning of solar cycle 22, it is believed that the reversal in the long-term solar constant trend may be linked to increased solar activity associated with the beginning of the 11-year sunspot cycle. The typical value of the solar constant was found to be 1365 Wm-2.

Lee, Robert B., III; Barkstrom, Bruce R.; Harrison, Edwin F.; Gibson, Michael A.; Natarajan, Sudha M.; Edmonds, William L.; Mecherikunnel, Ann T.; Kyle, H. Lee

1988-01-01

41

Earth Radiation Budget Satellite extraterrestrial solar constant measurements - 1986-1987 increasing trend  

Microsoft Academic Search

From June 1986 through Nov 1987, the Earth Radiation Budget Satellite (ERBS) pyrheliometric measurements indicated that the solar constant was increasing approximately +0.02 percent per year. Earlier ERBS measurements indicated that the solar constant was declining approximately -0.03 percent per year during the 1984 through mid-1986 period. Since mid-1986 represents the beginning of solar cycle 22, it is believed that

Robert B. Lee III; Bruce R. Barkstrom; Edwin F. Harrison; Michael A. Gibson; Sudha M. Natarajan; William L. Edmonds; Ann T. Mecherikunnel; H. Lee Kyle

1988-01-01

42

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

43

Life on other worlds : the twentieth century extraterrestrial life debate  

NASA Astrophysics Data System (ADS)

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

Dick, Steven J.

1998-12-01

44

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

45

Implications for global warming of intercycle solar irradiance variations  

NASA Astrophysics Data System (ADS)

The implications of solar irradiance variations on global warming are explored. Strong circumstantial evidence is provided that there have been intercycle variations in solar irradiance which have contributed to the observed temperature changes since 1856. However, it is found that since the nineteenth century greenhouse gases, not solar irradiance variations, have been the dominant contributor to the observed temperature changes.

Schlesinger, Michael E.; Ramankutty, Navin

1992-11-01

46

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

SciTech Connect

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

Sutton, Stephen R. [University of Chicago

2006-04-05

47

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

Microsoft Academic Search

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

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

1995-01-01

48

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

49

Cosmogenic nuclides in extraterrestrial materials  

Microsoft Academic Search

Research on cosmogenic nuclides in extraterrestrial materials is summarized. Methods for determining average production rates in meteorites are considered as well as the composition dependence of production rates. Also discussed are lunar meteorites, solar-gas-rich meteorites, presolar grains, and solar cosmic rays. 202 refs.

S. Vogt; G. F. Herzog; R. C. Reedy

1990-01-01

50

Modeled soft X-ray solar irradiances  

NASA Technical Reports Server (NTRS)

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

Tobiska, W. Kent

1994-01-01

51

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

Microsoft Academic Search

Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H)

Frans J. M. Rietmeijer

1990-01-01

52

The effects of sunspots on solar irradiance  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

53

Solar variability in irradiance and oscillations  

NASA Technical Reports Server (NTRS)

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

Kuhn, Jeff R.

1995-01-01

54

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

NASA Technical Reports Server (NTRS)

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

Ho, D.; Sobon, L. E.

1979-01-01

55

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

56

Extraterrestrial He in Sediments: From Recorder of Asteroid Collisions  

E-print Network

Extraterrestrial He in Sediments: From Recorder of Asteroid Collisions to Timekeeper of Global 3 He/4 He ratios during atmospheric entry heating. This extraterrestrial 3 He (3 HeET) is retained. As a tracer of fine-grained extraterrestrial material, 3 HeET offers unique insights into solar system events

Mukhopadhyay, Sujoy

57

Confronting a solar irradiance reconstruction with solar and stellar data  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

58

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

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics (LASP) has developed the LASP Interactive Solar IRradiance Datacenter (LISIRD, http://lasp.colorado.edu/lisird/) web site to provide access to a comprehensive set of solar irradiance measurements and related datasets. Current data holdings include products from NASA missions SORCE, UARS, SME, and TIMED-SEE. The data provided covers a wavelength range from soft X-ray (XUV) at 0.1 nm up to the near infrared (NIR) at 2400 nm, as well as Total Solar Irradiance (TSI). Other datasets include solar indices, spectral and flare models, solar images, and more. The LISIRD web site features updated plotting, browsing, and download capabilities enabled by dygraphs, JavaScript, and Ajax calls to the LASP Time Series Server (LaTiS). In addition to the web browser interface, most of the LISIRD datasets can be accessed via the LaTiS web service interface that supports the OPeNDAP standard. OPeNDAP clients and other programming APIs are available for making requests that subset, aggregate, or filter data on the server before it is transported to the user. This poster provides an overview of the LISIRD system, summarizes the datasets currently available, and provides details on how to access solar irradiance data products through LISIRD's interfaces.

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

2011-12-01

59

The calculated influence of atmospheric conditions on solar cell ISC under direct and global solar irradiances  

NASA Technical Reports Server (NTRS)

Calculations of the influence of atmospheric conditions on solar cell short-circuit current (Isc) are made using a recently developed computer model for solar spectral irradiance distribution. The results isolate the dependence of Isc on changes in the spectral irradiance distribution without the direct influence of the total irradiance level. The calculated direct normal irradiance and percent diffuse irradiance are given as a reference to indicate the expected irradiance levels. This method can be applied to the calibration of photovoltaic reference cells. Graphic examples are provided for amorphous silicon and monocrystalline silicon solar cells under direct normal and global normal solar irradiances.

Mueller, Robert L.

1987-01-01

60

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

61

Reconstruction of solar irradiance using the Group sunspot number  

Microsoft Academic Search

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,

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

2007-01-01

62

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

NASA Technical Reports Server (NTRS)

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

Rietmeijer, Frans J. M.

1990-01-01

63

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 of solar dataset or time-series is addressed with the example of the French national meteorological network

Recanati, Catherine

64

Photoelectrons as a tool to evaluate spectral variations in solar EUV irradiance over solar cycle timescales  

Microsoft Academic Search

There is limited information about the relative magnitude of the spectral variations in the ionizing component of solar irradiance on solar cycle timescales. We found that the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)\\/Solar Extreme Ultraviolet Experiment (SEE) Version 9 irradiance values predict relatively more ionospheric heating at solar minimum than those from Version 8. These changes have direct impacts

W. K. Peterson; E. N. Stavros; P. G. Richards; P. C. Chamberlin; T. N. Woods; S. M. Bailey; S. C. Solomon

2009-01-01

65

Forecasting Solar EUV Irradiance, Validation and Automation  

NASA Astrophysics Data System (ADS)

A new forecasting technique of the EUV solar irradiance was developed and a test case tried. This method is based on physical semi-empirical models of the solar atmosphere that are essentially different from empirical proxies based only on mathematical correlation. The physics based forecast can readily incorporate the large body of solar physics and radiative transfer knowledge, and any future developments in the understanding of the physical processes that operate in the solar atmosphere. In this paper it is shown how this forecast method is applied to a wide range of wavelengths and produces indices related to Earth upper atmospheric processes that can be correlated to observed patterns, as well as full spectra in the range 0.2 nm to 12 micron that can be utilized in GCM models. It is also shown how the forecast method is now in the process of being automated and applied to the onset of the solar activity cycle 24. In addition to the GONG and SWAN helioseismic and Ly alpha backscattering data, respectively, and the ground-based PSPT data, new measurements by SDO instruments (AIA and EVE) are being used to feed current data into the forecast technique. Furthermore, SDO/EVE data is starting to being used to validate the forecast in a substantial part of the UV range, from 6 to 100 nm.

Fontenla, J. M.; Gonzalez Hernandez, I.; Quémerais, E.; Lindsey, C.; Mason, J. P.

2010-12-01

66

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

67

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

68

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

69

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

70

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

71

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

72

Solar extreme ultraviolet irradiance: Present, past, and future  

Microsoft Academic Search

New models of solar extreme ultraviolet (EUV) irradiance variability are constructed in 1 nm bins from 0 to 120 nm using multiple regression of the Mg II and F10.7 solar activity indices with irradiance observations made during the descending phase of cycle 23. The models have been used to reconstruct EUV spectra daily since 1950, annually since 1610, to forecast

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

2011-01-01

73

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 Utrecht ABSTRACT In this paper, we describe a surveillance procedure for grid connected photovoltaic (PV of a year offering 90 % of the annual solar irradiation. 1 INTRODUCTION Photovoltaic (PV) Systems generate

Heinemann, Detlev

74

Reconstruction of solar irradiance since 1610: Implications for climate change  

Microsoft Academic Search

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

Judith Lean; Juerg Beer; Raymond Bradley

1995-01-01

75

Solar irradiance variations due to active regions  

SciTech Connect

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

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

1982-05-15

76

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$^{-2}$}.

Balmaceda, L; Solanki, S K

2007-01-01

77

Long-term variations in total solar irradiance  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

78

A reference solar spectral irradiance for use in atmospheric modeling  

NASA Technical Reports Server (NTRS)

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

1982-01-01

79

Utilization of extraterrestrial resources: the US case  

SciTech Connect

This is a policy oriented work that examines the possibilities of utilization of extraterrestrial space resources by the United States public and private sectors alike. Specific emphasis is placed on the resources of space located up to the geosynchronous orbit. Resources examined include the space vacuum, the infinitesimally small gravitational forces, the extraterrestrial solar energy, and the geosynchronous orbit. The impact of extraterrestrial resources is analyzed vis-a-vis the United States security, energy, economic, technological, and political (domestic, international) concerns. Scenarios to promote the efficient utilization of these resources are considered, and cost-benefit analyses are developed to examine the degree of justification of these undertakings.

Kraniou, D.J.

1984-01-01

80

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

Microsoft Academic Search

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

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

2004-01-01

81

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

NASA Astrophysics Data System (ADS)

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

Dick, Steven J.

2001-06-01

82

Long-term downward trend in total solar irradiance.  

PubMed

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

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

1986-11-28

83

Extraterrestrial materials processing  

NASA Technical Reports Server (NTRS)

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

Steurer, W. H.

1982-01-01

84

The extraterrestrial UV-background and the nearby interstellar medium  

Microsoft Academic Search

Recent measurements of the extraterrestrial UV- and EUV-radiation, and the various theoretical approaches used in explaining the measured features of these radiations are reviewed. Whereas the structures and intensities of extraterrestrial EUV-radiation are essentially undetermined up to now, the observations of the extraterrestrial UV-sky give a clear indication of the existence of neutral interstellar hydrogen within the solar system.

H. J. Fahr

1974-01-01

85

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

86

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

87

White Paper on SBUV/2 Solar Irradiance Measurements  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

88

Variations in solar Lyman alpha irradiance on short time scales  

NASA Technical Reports Server (NTRS)

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

Pap, J. M.

1992-01-01

89

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

90

Reconstructions of solar irradiance on centennial time scales  

NASA Astrophysics Data System (ADS)

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

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

91

The solar spectral irradiances from x ray to radio wavelengths  

NASA Technical Reports Server (NTRS)

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

White, O. R.

1993-01-01

92

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

93

Influence of Extraterrestrial Radiation on Radiation Portal Monitors  

Microsoft Academic Search

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,

Paul E. Keller; Richard T. Kouzes

2009-01-01

94

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

95

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 the isotopic records of extraterrestrial materials range widely in environmental conditions from very high in the solar nebula to lower temperature fluid-rock interactions in asteroids and planets. In extraterrestrial

96

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

97

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.

98

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

99

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

PubMed

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

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

1979-05-11

100

Evaluation of enhancement events of total solar irradiance during cloudy conditions at Granada (Southeastern Spain)  

NASA Astrophysics Data System (ADS)

Among the factors affecting the solar radiation that reaches the ground, clouds play a key role in its short-term variability causing events ranging from almost total reduction to substantial enhancements under particular conditions. The purpose of this paper is to detect and to analyze the enhancement events on total solar horizontal irradiance at Granada (Southeastern Spain) using one-minute data during a study period of five years (January 2006 to December 2010). For this goal, an empirical model for cloud-free conditions has been used together with information on cloud cover (i.e., oktas) provided by a sky camera. Around 6% of the one-minute data were classified as enhancements, but only those episodes with duration longer than 5 min were studied. For all these episodes, the relative increases over the expected cloud-free values were, on average, 13.5%, reaching maximum values up to 50%. The enhancement episodes were related to broken-cloud situations (2-7 oktas) without prevalence for a particular number of oktas. The analysis of the seasonal distribution of those events showed that ~ 50% of them occur in spring, followed distantly by the other seasons with percentages below 20%. Additionally, a long enhancement event (74 min) was analyzed in detail, showing the relevant role of the diffuse component in this event. Finally, extreme enhancements (those episodes with surface solar levels higher than their extraterrestrial value) were also reported, consisting in 0.14% of the one-minute data. They occurred only under heavy cloudy situations (6-7 oktas), showing relative increases between 30% and 60% with respect to expected cloud-free conditions.

Piedehierro, A. A.; Antón, M.; Cazorla, A.; Alados-Arboledas, L.; Olmo, F. J.

2014-01-01

101

Uncertainty analysis of solar simulator's spectral irradiance measurement  

NASA Astrophysics Data System (ADS)

Solar simulator is a key instrument for photovoltaic field, which aims to act the role of natural sunlight irradiance indoor, and we should identify how similar they are in quantity. The critical factor of similarity lies in its spectral irradiance, because of solar cells' wavelength-dependent spectral responsivity, spectral mismatch of solar simulator and sunlight can induce large errors during characteristic parameters measurement. In this article, a method for measuring solar simulator's spectral irradiance was proposed along with its uncertainty analysis. A calibrated fiber optic spectrometer was employed here for spectral measurement, which was used for calibrating various kinds of solar simulators manufactured with different mechanisms. Considering three main sources of measurement uncertainty, that is, the declared uncertainty of the calibrated spectrometer (u1), cosine correction (u2) and repeatability of measurement (u3), we estimated its combined expanded uncertainty is U = 6.2% (with coverage factor k = 2). Also, we have made a comparison of our spectral measurement results with methods traceable to other country's national institute of metrology, such as NIST traceable. This work is significant for the performance calibration and classification of solar simulators, so that plays a great role in solar energy industry.

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

2012-10-01

102

Solar cycle effects of spectrally varying solar irradiance in a coupled chemistry--climate model  

NASA Astrophysics Data System (ADS)

Variation of the solar spectral irradiance (SSI) with solar cycle impacts the composition and temperature of the atmosphere. Stratosphere ozone and temperature, for example, respond through both direct solar heating and photolysis. We have implemented an 11-year solar cycle in the Goddard Earth Observing System Chemistry--Climate Model (GEOS CCM). One of the SSI datasets used is a multi-decadal historical reconstruction based on contemporary observations of solar irradiance and historical proxies for solar activity. We examine the atmospheric response to SSI variations through direct solar heating and photolysis individually and also when coupled in the model. Ozone response is dominated by photolysis, whereas both direct heating and photolysis affect stratospheric temperatures approximately equally. We also find that the magnitude of the atmospheric response is sensitive to the spectral characteristics of the SSI dataset used.

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

2010-12-01

103

Modelling Solar Spectral Irradiance Variations at Ultraviolet Wavelengths  

NASA Technical Reports Server (NTRS)

Solar UV irradiance variations with solar activity are examined using a three component model of the CaII K chromospheric emission. This model, developed from ground based observations of the location, area and relative intensity of CaII K plage, in conjunction with measurements throughout solar cycle 21 of the full disc CaII K emission, includes the contributions to the ultraviolet flux from both plage and active network emission. The model successfully replicates changes in the Lyman alpha flux related to the 27 day rotation of solar plage, outbreaks (or rounds) of activity over periods of a year or more, and the growth and accumulation of active regions over the eleven year solar activity cycles. Estimates of the magnitude of the solar cycle variability of the UV emission between 200 and 300 nm are presented but cannot currently be verified by available observations.

Lean, J. L.; Livingston, W. C.; White, O. R.; Skumanich, A.

1984-01-01

104

Determinants of skin sensitivity to solar irradiation  

Microsoft Academic Search

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

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

2003-01-01

105

Thermal annealing of proton-irradiated silicon solar cells  

Microsoft Academic Search

Solar cells made from 1.5- and 10-??cm p-type silicon, with silver-titanium evaporated electrodes, were irradiated by 4.6-MeV protons at room temperature to fluences ranging from 1 × 1010to 1 × 1012protons\\/cm2. The photovoltaic current-voltage characteristics, the photovoltaic spectral response, and the minority carrier diffusion length were studied as the solar cells were annealed isochronally to temperatures up to 600°C. The

BRUCE J. FARADAY; R. L. Statler; REGINA V. TAUKE

1968-01-01

106

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

107

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

108

Evolution of the solar irradiance during the Holocene  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

109

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.

110

Solar irradiance variations in the visible and infrared - observations and model calculations  

Microsoft Academic Search

The Spectral Irradiance Monitor, SIM, is now providing the first continuous record of solar irradiance variations throughout the visible and near infrared. This instrument is aboard the Solar Radiation and Climate Experiment, SORCE, which was launched in January 2003. SIM is a prism spectrometer that makes precise measurements of the solar irradiance four times a day over the entire spectral

J. Harder; J. Fontenla; S. Davis; G. Rottman; T. Woods; O. White

2004-01-01

111

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

E-print Network

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

Nahar, Sultana Nurun

112

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

113

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 the possibility to test the claimed links between climate and TSI forcing. Citation: Steinhilber, F., J. Beer- gested by Tapping et al. [2007]. Moreover, Fro¨hlich [2009] shows that there is a strong correlation

Wehrli, Bernhard

114

Solar Forecasting System and Irradiance Variability Characterization  

E-print Network

variability. The report was submitted by HNEI to the U.S. Department of Energy Office of Electricity Delivery Variability in Hawai`i Prepared for the U.S. Department of Energy Office of Electricity Delivery and Energy of the Hawaiian Islands, with locations of the data sets used in the analysis 2 2. Statistics from irradiance

115

The Search for Extraterrestrial Artifacts (SETA)  

NASA Astrophysics Data System (ADS)

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

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

1984-10-01

116

Solar total irradiance and sunspot area in 1981  

NASA Technical Reports Server (NTRS)

Precise observations of the total solar irradiance in 1980 from the solar-maximum mission, showed a strong correlation with the projected total sunspot area. This correlation explained about half of the variance (r of about 0.75) in the total-irradiance data, leaving the other half for other solar phenomena and errors in the data. The analysis of the intervening three years of spin-mode data, which have reduced coverage, has begun. It is found that the correlation persists at about the same qualitative level, but with increased scatter that can be attributed to the smaller amount of data. The flatness of the distribution of areas of sunspot groups makes it possible to estimate PSI approximately from only the large groups.

Hudson, H. S.

1984-01-01

117

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

118

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

119

Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

120

The Search for Extraterrestrials  

NASA Astrophysics Data System (ADS)

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

Ross, Monte

121

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

122

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

123

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

124

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

125

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

126

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

SciTech Connect

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

Reda, I.

2011-07-01

127

XUV Photometer System (XPS): Improved Solar Irradiance Algorithm Using CHIANTI Spectral Models  

Microsoft Academic Search

Solar soft X-ray (XUV) radiation is highly variable on all time scales and strongly affects Earth’s ionosphere and upper atmosphere;\\u000a consequently, the solar XUV irradiance is important for atmospheric studies and for space weather applications. Although there\\u000a have been several recent measurements of the solar XUV irradiance, detailed understanding of the solar XUV irradiance, especially\\u000a its variability during flares, has

Thomas N. Woods; Phillip C. Chamberlin; W. K. Peterson; R. R. Meier; Phil G. Richards; Douglas J. Strickland; Gang Lu; Liying Qian; Stanley C. Solomon; B. A. Iijima; A. J. Mannucci; B. T. Tsurutani

2008-01-01

128

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

129

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

130

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

131

Solar irradiance forcing of centennial climate variability during the Holocene  

Microsoft Academic Search

Centennial climate variability during the Holocene has been simulated in two 10,000 year experiments using the intermediate-complexity ECBilt model. ECBilt contains a dynamic atmosphere, a global 3-D ocean model and a thermodynamic sea-ice model. One experiment uses orbital forcing and solar irradiance forcing, which is based on the Stuiver et al. residual 14C record spliced into the Lean et al.

S. L. Weber; T. J. Crowley; G. van der Schrier

2004-01-01

132

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

2006-04-19

133

Response of global upper ocean temperature to changing solar irradiance  

Microsoft Academic Search

By focusing on time sequences of basin-average and global-average upper ocean temperature (i.e., from 40øS to 60øN) we find temperatures responding to changing solar irradiance in three separate frequency bands with periods of >100 years, 18-25 years, and 9-13 years. Moreover, we find them in two different data sets, that is, surface marine weather observations from 1990 to 1991 and

Warren B. White; Judith Lean; Daniel R. Cayan; Michael D. Dettinger

1997-01-01

134

Spatial and temporal variability of global surface solar irradiance  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

135

UNCORRECTED Extraterrestrial He in Sediments  

E-print Network

UNCORRECTED PROOF 1 2 3 Extraterrestrial He in Sediments: 4 From Recorder of Asteroid Collisions 5 This extraterrestrial 3 He (3 HeET) is retained in sediments for geologically 15 long durations, having been detected in sedimentary rocks as old as 16 480 Ma. As a tracer of fine-grained extraterrestrial material, 3 HeET offers 17

Mukhopadhyay, Sujoy

136

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

137

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

138

Searching for extraterrestrial civilizations  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

139

Radiometer for accurate (+ or - 1%) measurement of solar irradiance equal to 10,000 solar constants  

NASA Technical Reports Server (NTRS)

The 10,000 solar constant radiometer was developed for the accurate (+ or - 1%) measurement of the irradiance produced in the image formed by a parabolic reflector or by a multiple mirror solar installation. This radiometer is water cooled, weighs about 1 kg, and is 5 cm (2 in.) in diameter by 10 cm (4 in.) long. A sting is provided for mounting the radiometer in the solar installation capable of measuring irradiances as high as 20,000 solar constants, the instrument is self calibrating. Its accuracy depends on the accurate determination of the cavity aperture, and absorptivity of the cavity, and accurate electrical measurements. The spectral response is flat over the entire spectrum from far UV to far IR. The radiometer responds to a measurement within 99.7% of the final value within 8 s. During a measurement of the 10,000 solar constant irradiance, the temperature rise of the water is about 20 C. The radiometer has perfect cosine response up to 60 deg off the radiometer axis.

Kendall, J. M., Sr.

1981-01-01

140

Extraterrestrial intelligence? The search is on  

NASA Technical Reports Server (NTRS)

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

Coulter, Gary R.

1991-01-01

141

Browsing, Understanding, and Accessing Solar Irradiance Data via LISIRD  

NASA Astrophysics Data System (ADS)

The Laboratory for Atmospheric and Space Physics, LASP, has been conducting research in Atmospheric and Space science for over 60 years. In particular, LASP has made a variety of space-based measurements of solar irradiance, which provide crucial input for research and modeling in solar-terrestrial interactions, space physics, planetary, atmospheric, and climate sciences. These data sets are generally time series of measurements, solar indices, and spectra. Unlike many Earth science data sets, they are not geolocated and so cannot be referenced via latitude and longitude coordinates. Thus they are not appropriate for or interoperable with many existing geo scientific data access and analysis tools and need somewhat specialized tools to aid users in their understanding and use. The LASP Solar Irradiance Data Center, LISIRD, http://lasp.colorado.edu/lisird, is designed to allow the science community and the public to explore and access solar irradiance and related data sets. LISIRD's interactive plotting allows users to investigate and download spectral data sets from a variety of missions. We have recently expanded our offerings and now serve TIMED SEE Level 2, Level 3, and Level 4 data sets. We continue to serve SORCE Solar Spectral Irradiance, Total Solar Irradiance, and Magnesium II and well as the Flare Irradiance Spectral Model (FISM) and other data sets. LISIRD leverages middleware, the LASP Time series Server (LaTiS), that provides access to time series data based on time, wavelength, and parameter. LaTiS can read a wide variety of input formats from both local and remote sources, so many data sets can be served in their native format. It also supports dynamic data reformatting, so users can request the data and times in formats of their choice. LaTiS supports data subsetting so that users may download only regions of interest, and can stream the data directly into a computer program via a RESTful API in an automated fashion. We continue to improve LISIRD not just by integrating new data sets, but also by improving its data management and presentation. This means assigning unique identifiers to data sets and the granules that constitute them, which will support better identification and citation of our data sets. We will explore identification issues and solutions related to the dynamic generation of new data sets enabled by LaTiS. We are also improving the access to our metadata, including semantically enabling the site so that our data can be discovered, related concepts can be explored, our inventory can be browsed and searched, and our data understood well enough to be understood and used appropriately. This poster will describe the current state of LISIRD, provide details of the data sets it serves, demonstrate the role of the LaTiS middleware, discuss the assignment of unique identifiers to our data products, describe plans for integration of a semantically metadata database, and address other related aspects of serving spectral and other time series data.

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

2012-12-01

142

Searching for extraterrestrial civilizations  

Microsoft Academic Search

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

T. B. H. Kuiper; M. Morris

1977-01-01

143

Search for extraterrestrial intelligence  

Microsoft Academic Search

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

P. Morrison; J. Billingham; J. Wolfe

1979-01-01

144

ExtraTerrestrial Intelligence  

E-print Network

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

Walter, Frederick M.

145

Panel Discussions on Total Solar Irradiance Variations and the Maunder Minimum  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

146

Isotopic anomalies and proton irradiation in the early solar system  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

147

The Role of Solar Flares in the Variability of the Extreme Ultraviolet Solar Spectral Irradiance  

NASA Astrophysics Data System (ADS)

X-ray and extreme ultraviolet (EUV, 0--121.6 nm) emission from the solar corona has long been used to provide insight into the dynamics and evolution of solar flares. The EUV Variability Experiment (EVE) onboard NASA's Solar Dynamics Observatory (SDO) measures the solar spectral irradiance in the EUV at a wide range of temperatures (7,000 K to 10 MK), capturing the complete evolution of the transition region and corona during solar flares. The goal of this thesis is to use the new observations obtained by EVE to quantify how the EUV spectral irradiance varies in response to solar flares. Most observation-based research on solar flares is done by studying individual, usually large, solar flares. My work takes a different approach. From 1 May 2010 to 31 August 2011, SDO observed over 750 solar flares. I created the EVE flare catalog to examine all of these events to produce a complete picture of the EUV variability of flares. In the process, I discovered that flares can be placed into one of five EUV flare categories. The EUV irradiance signature of these categories is unique and closely related to the magnetic structure of the flare region. Confined flares are the most ubiquitous type of flare. They are non-eruptive flares and appear as the sudden brightening of a coherent bundle of coronal loops. Localized eruptive flares are small point-like flares associated with EUV surges or jets. Arcade flares are the classic CSHKP-type flare and are identified observationally by an eruption followed by arcade of flare loops in the corona and two bright ribbons of footpoint emission in the chromosphere and transition region. EUV late phase flares are characterized by two spatially and temporally separate but related reconnection events. Finally, flares that do not fit into any of the four other flare categories are called "strange" flares. I also used the Enthaply-Based Thermal Evolution of Loops (EBTEL) code to model the heating rate of the corona during flares. By fitting the input parameters of the model to the EVE data, I determined that the rate of energy release during reconnection strongly influences the EUV irradiance signature. Each of these EUV flare categories has a different heating rate profile, which is related to the underlying magnetic structure of the flare region.

Hock, Rachel Allison

148

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

149

Radiation damage in proton irradiated indium phosphide solar cells  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

150

Preliminary low temperature electron irradiation of triple junction solar cells  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

151

An Independent Review of Existing Total Solar Irradiance Records  

NASA Astrophysics Data System (ADS)

With the advent of space-based total solar irradiance (TSI) observations about 35 years ago, researchers' understanding of solar variability and its causes has greatly improved. Controversies regarding the cross-calibration of the data from various TSI instruments have resulted in many different TSI composite time series. These composites agree well with each other on timescales ranging from days to years, but due to the limited stability of the instruments contributing to the composites, their quality is not yet sufficient to unambiguously detect possible changes between subsequent cycle minima. In this paper, the construction of the three most prominent TSI composite time series and the underlying TSI models is addressed. The difficulties associated with the cross-calibration of the data are considered, and the viewpoints of the different groups involved in the development of the composites are discussed.

Zacharias, Pia

2014-07-01

152

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

E-print Network

is strongly influenced by solar activity, in particular irradiance in the extreme ultraviolet range (EUV) which modulates the ioni- zation rate. On the other hand, space weather effects like solar flares plasma circulation initiated when solar wind magnetic field connects with the Earth's magnetic field

Bergen, Universitetet i

153

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

PubMed Central

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

Zurbenko, Igor

2014-01-01

154

[An encounter with extraterrestrial intelligence].  

PubMed

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

Hisabayashi, Hisashi

2003-12-01

155

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

156

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

SAS Honors Seminar 256: Extraterrestrial Life 12/1/2011 #12; Readings for Tuesday Cushman responses to extraterrestrial life" #12; Audio recordings for Tuesday From the 2010 Royal Society conference "Towards a scientific and societal agenda on extraterrestrial life" (http

Baker, Andrew J.

157

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

158

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

159

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

Microsoft Academic Search

Solar radiation below 50 nm produces a substantial portion of the F region ionization and most of the E region ionization that drives chemical reactions in the thermosphere. Because of a lack of high temporal and spectral resolution Solar EUV and XUV observations, particularly below 27 nm, various solar irradiance models have been developed. We have developed a technique to

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

2010-01-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

161

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

162

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

163

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

164

The search for extraterrestrial intelligence  

Microsoft Academic Search

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

T. L. Wilson

2001-01-01

165

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

166

Identification of Extraterrestrial Microbiology  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

167

Relation of White Light Coronal Brightness to Total Solar Irradiance  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

168

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

169

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

NASA Technical Reports Server (NTRS)

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

Timothy, J. G.

1983-01-01

170

Optical Search for Extraterrestrial Intelligence with Air Cerenkov Telescopes  

Microsoft Academic Search

We propose using large Air Cerenkov telescopes (ACTs) to search for optical, pulsed signals from extraterrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of solar luminosities at a distance of 100 pc. The field of view for giant ACTs can be on the order of 10 square degrees, and they

David Eichler; Gregory Beskin

2001-01-01

171

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

172

The Extraterrestrial Life Debate from Antiquity to 1900  

NASA Astrophysics Data System (ADS)

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

Crowe, Michael J.; Dowd, Matthew F.

173

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

2000-10-20

174

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

175

A comparison of solar total irradiance observations from spacecraft: 1985-1992  

NASA Technical Reports Server (NTRS)

This paper presents a statistical comparison of the solar total irradiance measured from the Nimbus-7, the Solar Maximum Mission (SMM), the Earth Radiation Budget Satellite (ERBS), and the Upper Atmosphere Research Satellite (UARS) spacecraft platforms, for the period 1985-1992. The mean irradiance, standard deviation, and the correlation among the daily irradiance remained high during periods of high solar activity. Linear regression models are established to estimate the irradiance measurements from one platform by the others. The results are consistent with the observations. However, the Nimbus-7 ERB responses show a drift during 1989-1992. The absolute irradiance observed by each instrument varies within the uncertainty associated with the corresponding radiometer.

Mecherikunnel, A. T.

1994-01-01

176

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

PubMed

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

Meindl, Peter; Wähmer, Martin; Monte, Christian

2014-10-20

177

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

178

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

NASA Astrophysics Data System (ADS)

Improvements to spectral and temporal solar irradiances are often based upon increasingly accurate and precise measurements as well as upon better understood physics. This paper reports on one example in an emerging trend for solar irradiance models that can be characterized as hybrid irradiance modeling. Empirical and physics-based modeling of irradiances are combined and take advantage of strengths within both methods to provide a variety of solar irradiance products to science and engineering users. The SOLAR2000 (S2K) version 1.24 model (v1.24) described in this paper has gone through 17 upgrades since it was originally released in 1999 as v0.10 and now incorporates three theoretical continua, 13 rocket spectra, and time series data from five satellites using 17 instruments. S2K currently produces six integrated irradiance proxies for science and engineering applications in addition to spectrally resolved irradiances in three common wavelength formats. Integrated irradiance proxies include the E10.7 integrated EUV energy flux, QEUV total thermospheric EUV heating rate, PEUV hemispheric EUV power, T? exospheric temperature, RSN derived sunspot number, and S integrated spectrum. Besides three spectral wavelength and six integrated irradiance formats there are three time frames of historical, nowcast, and forecast irradiance products produced by four model grades. The Research Grade (RG) model is developed for aeronomical and climate change research, the Professional Grade (PG) model is developed for space system engineering applications, the Operational Grade (OP) model is developed for institutional and agency real-time operational space weather applications, and the System Grade (SY) model is developed for commercial operational and production applications. This report describes these model characteristics as well as the current state of operational irradiances which are now in the second release of a first generation forecast methodology. Forecast Generation 1x (FGen 1x) produces a 72-h forecast of E10.7 at high solar activity with 1-sigma uncertainties at the 8% level. All SOLAR2000 irradiance products from each of the versions, grades, and forecast generations are compliant with the ISO CD 21348 solar irradiance draft standard being developed as a standard method to specify all solar irradiances for use by space systems and materials users.

Tobiska, W. Kent

2004-01-01

179

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

180

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

181

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

182

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 of trends in direct normal irradiance from three sites around Oregon over a period of 25 years. An overall. Changes in clear noon values are also examined. This article analyzes direct normal data unlike other

Oregon, University of

183

Speculated Long-Term Trends in Solar Irradiance and Their Implications for the Future  

NASA Astrophysics Data System (ADS)

Solar irradiance varies in response to changes in solar magnetism. Enhanced emission in faculae is a primary source of total irradiance variability. Bright chromospheric plages and network overlying photospheric faculae are dominant sources of variations in UV irradiance that affect ozone, and in strong EUV emission lines that impact neutral and ionized densities in the upper atmosphere. Knowledge of the sources of long-term trends in solar irradiance is important for specifying the Sun's role in global change and space weather, in the past and in the future. Neither irradiance nor the chromospheric Ca and Mg indices that are sensitive indicators of bright emission sources, was monitored prior to 1976 so scenarios for their long-term variability must be developed indirectly. One approach utilizes the range of variability evident in Ca emission in Sun-like stars; another correlates measured solar fluxes with historical proxies of solar activity, such as the aa index. The amplitudes of long-term total solar irradiance variability estimated by these two independent approaches agree quite well. But irradiances reconstructed from smoothed group sunspot numbers increase primarily in the first part of the twentieth century and lack a significant long-term rising trend in their cycle minima in the past 50 years, such as is inferred from geomagnetic indices. The historical reconstructions, though speculative, provide a basis for assessing future solar irradiance trends. Progress in specifying the sources of long-term solar irradiance trends requires new understanding of how the closed flux associated with bright magnetic sources in the solar atmosphere relates to the open flux associated primarily with coronal holes. The closed flux produces irradiance variations whereas the open flux extends into the heliosphere, modulates the interplanetary magnetic field and produces geomagnetic activity. Initial results based on potential field extrapolations show that the emergence of new active regions together with flux transport processes continually alter the relative amounts of open and closed flux. Whether or not closed and open flux evolve differently or together over long time scales is presently unknown but is essential for determining the physical relevance of geomagnetic indices for inferring historical solar irradiance variations.

Lean, J. L.; Wang, Y.

2001-05-01

184

Extraterrestrial Radiation Chemistry and Molecular Astronomy  

NASA Technical Reports Server (NTRS)

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

Hudson, Reggie L.; Moore, Marla H.

2009-01-01

185

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

E-print Network

treatment of the diurnal variation of the solar irradiance, is described. 1 INTRODUCTION Remote Sensing from; 7-Instituto Tecnologico de Canarias; 8-Fraunhofer Institute for Solar Energy Systems; 9-German section 2) as well as by the development and establishment of a new type of calculation scheme. This new

Heinemann, Detlev

186

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

NASA Astrophysics Data System (ADS)

Knowledge of the top of the atmosphere (TOA) solar spectral irradiance (SSI) is crucial in interpreting the spectrally dependent radiative processes throughout Earth's climate system. Where this energy is deposited into the atmosphere and surface, how the climate responds to solar variability, and the mechanisms of climate response, are highly dependent on how the incident solar radiation is distributed with wavelength. In order to advance understanding of how natural and anthropogenic process affect Earth's climate system there is a strong scientific imperative to maintain accurate, long-term records of climate forcing and response. The contin-uation of SSI measurements provides a unique opportunity to characterize poorly understood wavelength dependent climate processes. Coupled chemistry-climate models require realistic assessments of the magnitudes and long-term trends in SSI for the interpretation and quantifi-cation of solar forcing in climate change scenarios. This places stringent requirements on the absolute calibration of the instrument (tied directly to international standards) and the ability to maintain that calibration on-orbit (long-term stability). The Spectral Irradiance Monitor (SIM) is a solar spectral radiometer that continuously monitors the SSI from 200 nm -2400 nm, a wavelength region encompassing 96% of the total solar irradiance. The SIM instrument is included as part of the Total and Spectral Solar Irradiance Sensor (TSIS) to continue the mea-surement of SSI, which began with the SOlar Radiation and Climate Experiment (SORCE), launched in 2003. SORCE SIM measurements have characterized SSI variability during the descending phase of Solar Cycle (SC) 23, but the determination of multi-solar cycle dependen-cies remains a key climatic uncertainty. Analysis of the measured spectral irradiance variability during the SORCE mission has resulted in a number of instrument design refinements central to maintaining, on-orbit, the long-term absolute calibration to the International System of Units (SI) irradiance standards (0.2% absolute) and achieve the necessary measurement precision and long-term reproducibility (0.05 -0.01% relative per year) to meet the needs for establishing a climate record of solar spectral irradiance. We will review the findings from the SORCE SIM observations over the past 7 years, a time period encompassing the declining phase of SC 23 and the start of SC 24, and how these results guided performance enhancements that will be applied to the TSIS SIM instrument to meet the needs for climate monitoring of solar spectral irradiance into the future.

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

187

Evidence of a long-term trend in total solar irradiance  

NASA Astrophysics Data System (ADS)

Aims: During the solar minimum of 2008, the value of total solar irradiance at 1 AU (TSI) was more than 0.2 Wm-2 lower than during the last minimum in 1996, indicating for the first time a directly observed long-term change. On the other hand, chromospheric indices and hence solar UV irradiance do not exhibit a similar change. Methods: Comparison of TSI with other activity parameters indicates that only the open solar magnetic field, BR, observed from satellites at 1 AU show a similar long-term behaviour. The values at the minima correlate well and the linear fit provides a direct physical relationship between TSI and BR during the minimum times. Results: This correlation allows an unambiguous reconstruction of TSI back in time, provided the open solar magnetic field can be determined from e.g. geomagnetic indices or cosmogenic radionucleides. Since the solar UV irradiance has no long-term trend, the mechanism for the secular change of TSI must differ from the effect of surface magnetism, as manifested by sunspots, faculae, and network which indeed explain well the intra-cycle variability of both total and spectral irradiance. Conclusions: The long-term trend of TSI is most probably caused by a global temperature change of the Sun that does not influence the UV irradiance in the same way as the surface magnetic fields. Appendix is only available in electronic form at http://www.aanda.org

Fröhlich, C.

2009-07-01

188

Application of Solar Spectral Irradiance Variability in a Earth Atmospheric Model  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

189

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

190

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

NASA Astrophysics Data System (ADS)

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

Eparvier, F. G.

2011-12-01

191

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

192

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

193

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

194

Extraterrestrial magnetic minerals  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

195

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

SciTech Connect

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

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

1992-01-01

196

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

SciTech Connect

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

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

1992-12-01

197

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

SAS Honors Seminar 256: Extraterrestrial Life 11/29/2011 #12; Reading for Thursday Review for Astrobiological Research The Ethics of Terraforming The History of SETI The Media's Portrayal of Extraterrestrial

Baker, Andrew J.

198

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

199

On the possible influence of extraterrestrial volatiles on Earth's climate and the origin of the oceans  

Microsoft Academic Search

A consideration of observational and circumstantial evidence suggests that Earth may be subject to high influx rates (1011–1012 kg\\/yr) of extraterrestrial-sourced volatile elements (carbon, hydrogen, oxygen, nitrogen) derived from comets or other primitive solar-system material. The total extraterrestrial influx rate may be four to five orders of magnitude greater than previously thought, large enough to account for today's total near-surface

David Deming

1999-01-01

200

Comparisons of estimated economic burdens due to insufficient solar ultraviolet irradiance and vitamin D and excess solar UV irradiance for the United States.  

PubMed

Vitamin D sufficiency is required for optimal health, and solar ultraviolet B (UVB) irradiance is an important source of vitamin D. UVB and/or vitamin D have been found in observational studies to be associated with reduced risk for over a dozen forms of cancer, multiple sclerosis, osteoporotic fractures, and several other diseases. On the other hand, excess UV irradiance is associated with adverse health outcomes such as cataracts, melanoma, and nonmelanoma skin cancer. Ecologic analyses are used to estimate the fraction of cancer mortality, multiple sclerosis prevalence, and cataract formation that can be prevented or delayed. Estimates from the literature are used for other diseases attributed to excess UV irradiation, additional cancer estimates, and osteoporotic fractures. These results are used to estimate the economic burdens of insufficient UVB irradiation and vitamin D insufficiency as well as excess UV irradiation in the United States for these diseases and conditions. We estimate that 50,000-63,000 individuals in the United States and 19,000-25,000 in the UK die prematurely from cancer annually due to insufficient vitamin D. The U.S. economic burden due to vitamin D insufficiency from inadequate exposure to solar UVB irradiance, diet, and supplements was estimated at $40-56 billion in 2004, whereas the economic burden for excess UV irradiance was estimated at $6-7 billion. These results suggest that increased vitamin D through UVB irradiance, fortification of food, and supplementation could reduce the health care burden in the United States, UK, and elsewhere. Further research is required to confirm these estimates. PMID:16159309

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

2005-01-01

201

A Comparison of Total Solar Irradiance to the Mg II Index Based on SORCE Measurements  

NASA Astrophysics Data System (ADS)

The reconstruction of the total solar irradiance (TSI) over the long-term often uses sunspot area and a faculae proxy such as the Mg II core-to-wing index (Mg index). With interest in validating this approach, we compare the Mg index to TSI measurements using data from NASA's SOlar Radiation and Climate Experiment (SORCE). The SORCE carries four solar irradiance instruments that have been monitoring the Sun since early 2003. The Total Irradiance Monitor (TIM) measures the TSI with unprecedented stability and low noise during the daytime portion of each spacecraft orbit with a time cadence of 100 seconds. The SOLar STellar Irradiance Comparison Experiment (SOLSTICE) measures solar spectral irradiance from 115 to 320 nm, having 0.1 nm spectral resolution at the Mg II lines near 280 nm. The Mg II lines are scanned approximately seven times each day, and the Mg index provides a good indicator of chromospheric activity. We compare the SOLSTICE Mg II core-to-wing index to TIM TSI measurements, giving advantages over previous comparisons including simultaneity, low noise, and high spectral resolution for the Mg II lines.

Kopp, G.; Snow, M.; McClintock, W.; Woods, T.

2005-05-01

202

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

NASA Astrophysics Data System (ADS)

NOAA's planned Total and Spectral Solar Irradiance Sensor (TSIS) mission will fly along with the NOAA user service payloads Advanced Data Collection System (ADCS) and Search and Rescue Satellite Aided Tracking (SARSAT). In order to guarantee continuity in the 33-year solar irradiance climate data record, TSIS must be launched in time to overlap with current on-orbit solar irradiance instruments. Currently TSIS is moving towards a launch readiness date of January 2015. TSIS provides for continuation of the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) currently onboard NASA's Solar Radiation and Climate Experiment (SORCE) platform, launched in January 2003. The difficulty of ensuring continuity has increased due to the launch failure of NASA's Glory mission with its improved TIM. Achieving the needed overlap must now rely on extending SORCE, and maintaining the TSIS schedule. TSIS is one component of a NASA-NOAA joint program (JPSS) planned to transition certain climate observations to operational mode. We summarize issues of continuity, improvements being made to the TIM and SIM sensors, and plans to provide for traceability of total and spectral irradiance measurements to ground-based cryogenic standards.

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

2012-04-01

203

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

NASA Technical Reports Server (NTRS)

Satellite observations of the sun over almost five years have shown that principally two UV active longitudes have persisted over a significant portion. A comparison between the position of solar magnetic sector boundaries and UV enhancements of the sun indicates that the UV maxima tend to occur near the times when a solar sector boundary is near central meridian. An estimate of the magnitude of the variable UV solar energy input into the atmosphere resulting from the rotation of active solar longitudes is that for wavelengths less than 175 nm and down to H. Lyman-alpha it exceeds the annual variation, whereas at longer wavelengths it is less. The total observed peak-to-peak variation in the UV irradiance from 120 to 300 nm over a solar rotation is typically at least 230 ergs/sq cms.

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

1974-01-01

204

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.

205

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

206

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

207

Evidence for High-Energy Extraterrestrial Neutrinos  

E-print Network

Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector IceCube Collaboration, however, consistent with generic predictions for an additional component of extraterrestrial origin. H igh of an extraterrestrial source (3). Although that analysis had some sensitivity to neutrino events of all flavors above 1

Woschnagg, Kurt

208

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

SAS Honors Seminar 256: Extraterrestrial Life 11/22/2011 #12; Where are the Pioneers on discovery of extraterrestrial (un)intelligence McKay (2009) & Bailey (2011) ­ deliberately terraforming Research The History of SETI The Media's Portrayal of Extraterrestrial Life and its Influence on Public

Baker, Andrew J.

209

ADVANCING THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE  

E-print Network

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

210

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

], which is the portion of the total solar irradiation that is most useful for solar concentrators. Solar concentrators that can concentrate in excess of 500 times the solar flux are currently considered the most

Cerpa, Alberto E.

211

Short-term changes in solar spectral irradiance - synthesis calculations  

Microsoft Academic Search

We present the latest results from the SunRISE spectral synthesis in specific spectral bands in the UV, visible, and near-IR in response to short-term (days-months) solar activity in the latter stage of solar cycle 23 and compare to observations from SORCE\\/SIM and other datasets. We will comment on the degree of redundancy in parts of the solar spectrum and how

O. R. White; P. A. Fox

2004-01-01

212

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

213

The collection and analysis of extraterrestrial dust particles  

NASA Technical Reports Server (NTRS)

Techniques used for the collection of interplanetary dust particles (IDPs) from the earth's surface, upper atmosphere, and space and for the particles' curation and examination are discussed together with the properties of the collected IDPs and the information available on the interplanetary and interstellar dust from astronomical observations. Consideration is given to the physical and spectral properties of chondritic IDPs as well as of nonchondritic Al- and Ca-rich particles of extraterrestrial origin. Special attention is given to the determination of the sources of the extraterrestrial particles by spectral comparisons with meteorites, asteroids, and comets and by examination of the solar flare track densities within mineral grains in the IDPs. A spectral comparison with interstellar spectra revealed common features supporting the belief that some of the collected IDPs contain 'primitive' components that date back to the origin of the solar system and perhaps beyond.

Sandford, Scott A.

1987-01-01

214

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

215

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

216

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

NASA Technical Reports Server (NTRS)

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

Lee, T.

1978-01-01

217

Solar irradiance variations in the visible and infrared - observations and model calculations  

NASA Astrophysics Data System (ADS)

The Spectral Irradiance Monitor, SIM, is now providing the first continuous record of solar irradiance variations throughout the visible and near infrared. This instrument is aboard the Solar Radiation and Climate Experiment, SORCE, which was launched in January 2003. SIM is a prism spectrometer that makes precise measurements of the solar irradiance four times a day over the entire spectral range 200-2700 nm. The SIM data provide important new information on both the mechanisms of solar variability and on how the changing Sun influences our terrestrial environment. One important new finding has resulted from a comparison of SIM observations with corresponding spectral irradiance time series synthesized by the model of Fontenla, White, Fox, Avrett, and Kurucz (ApJ, 1999, 518, 480). Their model directly accounts for the distribution and evolution of features on the Sun that contribute to irradiance variations. This SUNRISE model uses seven semi-empirical spectral models to represent sunspots, plage, network, and quiet atmosphere, and these models are then combined according to a decomposition of solar images. The comparison of the model and observations indicate good agreement at visible wavelengths, but in the infrared the model and observations differ significantly. The models assume that in the infrared, near the peak of the H- opacity at about 1600 nm, the active regions are somewhat dark relative to the quite Sun decreasing the irradiance when they are present. The IR disagreements between the SIM observations and the models indicate that the "dark plage" assumptions used in the model(s) will need to be adjusted. The models must incorporate "bright plage" at all wavelengths so that the infrared irradiance will vary in a manner similar to the shorter wavelength visible and ultraviolet wavelength.

Harder, J.; Fontenla, J.; Davis, S.; Rottman, G.; Woods, T.; White, O.

218

A lunar base for SETI (Search for Extraterrestrial Intelligence)  

NASA Technical Reports Server (NTRS)

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

Oliver, Bernard M.

1988-01-01

219

Evaluation of solarization resistant optical fibers under gamma-ray irradiation and temperature stress  

Microsoft Academic Search

Five types of large diameter optical fibers (600 ?m and 1000 ?m core diameter) having either an enhanced UV transmission or being solarization resistant were subjected to gamma-ray irradiation, at a dose rate of 0.3 kGy\\/h ± 5%, up to a total irradiation dose of 113 kGy, at room temperature. The radiation induced optical absorption in the UV-visible spectral range

Dan Sporea; Adelina Sporea

2005-01-01

220

Mechanism of degradation of electrolyte solutions for dye-sensitized solar cells under ultraviolet light irradiation  

NASA Astrophysics Data System (ADS)

We studied the mechanism of the degradation of I-/I3--containing electrolyte solutions for dye-sensitized solar cells under UV light irradiation. The yellow electrolyte solutions underwent achromatization during irradiation, indicating the reduction of I3-. We propose a mechanism involving the production of holes in TiO2, reaction of the holes with solvent molecules, and subsequent reduction of I3- by electrons remaining in the TiO2. Although the quantum yield of the photodegradation reaction is estimated to be low (3 × 10-3), this reaction can nevertheless be expected to affect the long-term stability of dye-sensitized solar cell devices.

Nakajima, Shohei; Katoh, Ryuzi

2015-01-01

221

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

222

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

PubMed

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

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

2014-08-20

223

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

NASA Technical Reports Server (NTRS)

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.

1988-01-01

224

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

225

Can Collimated Extraterrestrial Signals be Intercepted?  

E-print Network

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

Forgan, Duncan H

2014-01-01

226

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

227

Nuclear power: key to man's extraterrestrial civilization  

SciTech Connect

The start of the Third Millennium will be highlighted by the establishment of man's extraterrestrial civilization with three technical cornerstones leading to the off-planet expansion of the human resource base. These are (1) the availability of compact energy sources for power and propulsion, (2) the creation of permanent manned habitats in space, and (3) the ability to process materials anywhere in the Solar System. In the 1990s and beyond, nuclear reactors could represent the prime source of both space power and propulsion. The manned and unmanned space missions of tomorrow will demand first kilowatt and then megawatt levels of power. Various nuclear power plant technologies will be discussed, with emphasis on derivatives from the nuclear rocket technology.

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

1982-01-01

228

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

Microsoft Academic Search

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

Bailey

1995-01-01

229

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

230

Climate signature of solar irradiance variations: analysis of long-term instrumental, historical, and proxy data  

Microsoft Academic Search

The signature of solar irradiance variations on decadal-to-centennial climate variability is analysed by means of statistical analysis of long-term instrumental, historical, and proxy data sets. Solar variations associated with the Schwabe, Hale, and Gleissberg cycles are detected by their spatial patterns in sea-surface temperature and sea-level pressure. Different statistical methods for instrumental and proxy data show that the mode related

Gerrit Lohmann; Norel Rimbu; Mihai Dima

2004-01-01

231

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

232

The search for extraterrestrial intelligence  

Microsoft Academic Search

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

Barrie W Jones

2003-01-01

233

The Search for Extraterrestrial Intelligence.  

ERIC Educational Resources Information Center

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

Jones, Barrie W.

2003-01-01

234

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

235

Beyond Earth: How extra-terrestrial volcanism stretches our definition of a volcano  

Microsoft Academic Search

Volcanism is a fundamental geologic process that has affected every solid body in the solar system and, presumably, in other solar systems as well. As we explore other worlds, we come across signs of active and past volcanism, some in unexpected places. Volcanism in extraterrestrial worlds can be much different from the examples we see on Earth, but the similarities

R. Lopes

2007-01-01

236

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

NASA Technical Reports Server (NTRS)

The uncertainty in ground-based estimates of solar irradiance is quantitatively related to the temporal variability of the atmosphere's optical thickness. The upper and lower bounds of the accuracy of estimates using the Langley Plot technique are proportional to the standard deviation of aerosol optical thickness (approx. +/- 13 sigma(delta tau)). The estimates of spectral solar irradiance (SSI) in two Cimel sun photometer channels from the Mauna Loa site of AERONET are compared with satellite observations from SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on UARS (Upper Atmospheric Research Satellite) for almost two years of data. The true solar variations related to the 27-day solar rotation cycle observed from SOLSTICE are about 0.15% at the two sun photometer channels. The variability in ground-based estimates is statistically one order of magnitude larger. Even though about 30% of these estimates from all Level 2.0 Cimel data fall within the 0.4 to approx. 0.5% variation level, ground-based estimates are not able to capture the 27-day solar variation observed from SOLSTICE.

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

2003-01-01

237

ACRIM total solar irradiance satellite composite validation versus TSI proxy models  

NASA Astrophysics Data System (ADS)

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

Scafetta, Nicola; Willson, Richard C.

2014-04-01

238

Disinfection of contaminated water by using solar irradiation.  

PubMed

Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min. PMID:14766599

Caslake, Laurie F; Connolly, Daniel J; Menon, Vilas; Duncanson, Catriona M; Rojas, Ricardo; Tavakoli, Javad

2004-02-01

239

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

240

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

241

Space Weathering of TNOs: Constraints from Laboratory Experiments on Extraterrestrial Carbons and Analogs  

NASA Astrophysics Data System (ADS)

Complex organic materials on small outer Solar System icy bodies probably include a primary native component accreted during the formation of planetesimals, and a secondary component that is a by-product of (cosmic and/or solar wind) ion and photon irradiation of simpler C-bearing volatile ices such as CH4, CH3OH, etc. This irradiation-induced processing of surfaces is known as space weathering (SW). Although less abundant than the primary native component, this secondary SW-produced organic component can strongly affect the remote sensing studies of Centaurs and trans-Neptunian objects (TNOs). In fact, SW may play an important role in determining the observed spectral variety of these objects, in particular the low surface albedos and the variety of colors from red to black that are commonly attributed to organic compounds and carbonaceous refractories. In order to de-bias the observations from the SW component and to better constrain these processes, laboratory experiments are needed. Here I will show spectroscopic data of some irradiated laboratory analogs: organic icy residues, soot, and hydrogenated amorphous carbon. These data will be compared with those of some chondritic porous interplanetary dust particles of cometary origin. I will discuss how this comparison can provide interesting inputs and help constraining the origin of TNO organic materials. In particular, I will emphasize the role of Raman spectroscopy in characterizing the structural properties of the analyzed samples, in interpreting the observed heterogeneity of the extraterrestrial carbonaceous component, and in constraining the irradiation dose accumulated before and after the formation of planetesimals.

Brunetto, R.

2011-12-01

242

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

NASA Astrophysics Data System (ADS)

Measurements of the distributions of the aerosol characteristics and solar ultraviolet irradiance were conducted by using instrumentation flown on a Falcon aircraft over the entire Greek area from the sea up to the middle troposphere. To study the impact of the aerosol abundance to the solar ultraviolet irradiance at various altitudes, complementary observations of ozone concentration, relative humidity, and temperature have been also performed using instrumentation flown on free balloons. In addition to a detailed description of the observed aerosol characteristics we attempt an improvement of the earlier proposed theoretical algorithms regarding the absolute values of the solar ultraviolet irradiance at various tropospheric altitudes. This is achieved by taking into account the measured accumulation aerosol particle and cloud droplet size distributions. The measurements showed that a double-layer structure in the vertical distribution of the number density of the cloud droplets and particle size aerosol was prevalent. In particular, over the area west of Crete the aerosol particles possessed a bimodal size distribution with mean diameters of 0.11 and 0.225 ?m. Moreover, upon using the obtained aerosol distribution data in the radiative transfer calculations, we find that the calculated values of the solar ultraviolet irradiance correlate well with the observed ones, showing an 4.3 ± 0.1% km-1 increase for altitudes ranging from the ground to 6.2 km.

Varotsos, Costas

2005-05-01

243

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

244

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

246

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

SciTech Connect

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

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

2014-12-08

247

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

248

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

249

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

250

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

251

TOTAL SOLAR IRRADIANCE VARIATION DURING RAPID SUNSPOT H. JABRAN ZAHID1, HUGH S. HUDSON1 and CLAUS FRHLICH2  

E-print Network

of correlation, a result consistent with a large thermal conductivity in solar convection zone. In addition weTOTAL SOLAR IRRADIANCE VARIATION DURING RAPID SUNSPOT GROWTH H. JABRAN ZAHID1, HUGH S. HUDSON1 December 2003; accepted 23 March 2004) Abstract. Large sunspot areas correspond to dips in the total solar

California at Berkeley, University of

252

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

253

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

254

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

NASA Technical Reports Server (NTRS)

Monitoring of the near ultraviolet (UV) solar irradiance is important because the solar UV radiation is the primary energy source in the upper atmosphere. The solar irradiance at wavelengths shortward of roughly 300 nm heats the stratosphere via photodissociation of ozone in the Hartley bands. Shortward of 242 nm the solar UV flux photodissociates O2, which is then available for ozone formation. Upper stratosphere ozone variations coincident with UV solar rotational modulation have been previously reported (Gille et al., 1984). Clearly, short and long term solar irradiance observations are necessary to separate solar-forced ozone variations from anthropogenic changes. The SBUV/2 instrument onboard the NOAA-9 spacecraft has made daily measurements of the solar spectral irradiance at approximately 0.15 nm intervals in the wavelength region 160-405 nm at 1 nm resolution since March 1985. These data are not needed to determine the terrestrial ozone overburden or altitude profile, and hence are not utilized in the NOAA Operational Ozone Product System (OOPS). Therefore, assisted by the ST System Corporation, NASA has developed a scientific software system to process the solar sweep mode data from the NOAA-9 instrument. This software will also be used to process the sweep mode solar irradiance data from the NOAA-11 and later SBUV/2 instruments. An overview of the software system and a brief discussion of analysis findings to date are provided. Several outstanding concerns/problems are also presented.

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

1990-01-01

255

Extraterrestrial Mössbauer spectrometry  

Microsoft Academic Search

We describe a combined backscatter Mössbauer spectrometer and X-ray fluorescence analyzer (BaMS\\/XRF) instrument suitable for\\u000a planetary missions to the surfaces of Mars (MESUR Program), the Moon, asteroids, or other solid solar-system objects. The\\u000a BaMS\\/XRF instrument is designed to be capable of concurrent analysis of a sample for its elemental abundances (XRF) and for\\u000a the mineralogy of its iron-bearing phases (BaMS)

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

1992-01-01

256

Total solar irradiance variation during rapid sunspot H. Jabran Zahid  

E-print Network

pattern of correlation, a result consistent with a large thermal conductivity in solar convection zone that the sunspot deficit will simply diffuse throughout the convection zone and subsequently re-appear only are comparable to the rotation period of the Sun. As a result the purely geometrical foreshortening of sunspot

Hudson, Hugh

257

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.

258

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

259

The search for extraterrestrial intelligence  

Microsoft Academic Search

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

Carl Sagan; Frank Drake

1975-01-01

260

Extraterrestrial accretion and glacial cycles  

NASA Technical Reports Server (NTRS)

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

Muller, R. A.

1994-01-01

261

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

NASA Technical Reports Server (NTRS)

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

Simon, P. C.

1983-01-01

262

Markov processes and Zipf's law in daily solar irradiation at earth's surface  

NASA Astrophysics Data System (ADS)

Sequences of two consecutive days of solar irradiation (global horizontal and direct normal) have been studied here by different approaches. The frequency vs. rank relationships have been analyzed as an attempt to explore whether the Zifp's law is fulfilled, yielding to a partial fulfillment and observing that a good logarithmic fit can be applied to the data in the whole range. In addition, the pdfs of increments in two consecutive daily irradiation values are also studied, showing a relationship between persistence and the coefficients of the logarithmic fit. Finally, it has been shown that a Markov process can represent properly sequences of two consecutive daily irradiation values, for both global horizontal and direct normal components. Thus, synthetic series can be generated by Markov chains for characterizing daily global and direct irradiation.

Vindel, J. M.; Polo, J.

2014-01-01

263

The response of the MLS mesospheric daytime hydroxyl radical and water vapor to the short-term solar irradiance variability  

NASA Astrophysics Data System (ADS)

Solar radiation, which is the main energy source in the terrestrial atmosphere, is highly variable on different time-scales. The variations of the SSI may have substantial impact on chemical and physical processes in the atmosphere. The mesospheric hydroxyl radical (OH), which is the main ozone destructor, is produced due to the photolysis of the water vapor (H2O) by highly variable short wave solar radiation. Chemistry-climate models suggest strong response of the mesospheric OH and H2O caused by the solar irradiance variability. However the response was not yet defined with observed data. We analyzed the response of the tropical mean OH and H2O data observed by Aura Microwave Limb Sounder (MLS) to the solar irradiance variations during rotational cycle. We performed the analysis for the two time periods. The data from December 2004 to December 2005 were used to estimate the OH and H2O responses to the solar irradiance variability in high solar activity conditions (when the 27-day rotational cycle is well pronounced). The response for the solar minimum conditions (when the 27-day rotational cycle is vague) was considered using the data from November 2008 to November 2009. We found, for the first time, that during the period of the high solar activity the daily time series of the mesospheric OH correlate well with the solar irradiance at zero time-lag and the correlation coefficient reaches 0.79 at 76-82 km. The H2O for the same period anticorrelates with the solar irradiance at about 6-7 days time-lag with the correlation coefficient up to -0.7. At the same time the OH and H2O responses are negligible for the solar minimum period. This confirms that the 27-day solar cycles in OH, H2O and solar irradiance are physically connected.

Shapiro, A. V.; Rozanov, E.; Shapiro, A.; Wang, S.; Egorova, T. A.; Schmutz, W. K.; Peter, T.

2011-12-01

264

Solar Spectral Irradiance under Clear Skies around a Major Metropolitan Area.  

NASA Astrophysics Data System (ADS)

This paper investigates the influence of gaseous pollutants and aerosol on the spectral composition of various segments of the solar spectrum in cloudless conditions. This investigation is done by using data of the spectral energy distribution of global and diffuse solar irradiances collected during a field experiment in Athens. The authors found that the Ångström turbidity coefficient always shows a temporal pattern with high values in the morning and the afternoon and low values at midday, and the wavelength exponent widely varies over 1.02-1.4.Atmospheric turbidity produced a measurable but variable effect on spectral solar irradiances. The authors found that the relative attenuations caused by high urban aerosol can exceed 36% ± 7.5%, 30% ± 5.8%, and 26% ± 4.1% in the ultraviolet, visible, and near-infrared portions of the solar spectrum, respectively, as compared with `background' values. On the other hand, the relative increase in scattered irradiance was greater in the near-infrared band (40% ± 4.8%), and in visible and ultraviolet bands the relative increase reached 31% ± 5.5% and 18% ± 6.5%, respectively.Spectrally reduced (Rayleigh corrected) and aerosol (Ångström) optical depths were retrieved, representing different aerosol loadings over the Athens atmosphere. The effects of altitude and the temporal and spatial variability of spectral optical depth values were analyzed. The overall results suggest that the shortest wavelengths are very sensitive to aerosol loading.

Jacovides, C. P.; Steven, Michael D.; Asimakopoulos, D. N.

2000-06-01

265

Analysis of Ca II K spectroheliogram time-series for solar irradiance studies  

NASA Astrophysics Data System (ADS)

Historic Ca II K observations constitute an extremely valuable resource for many research topics, including investigations of solar activity and irradiance variations on century timescales. In fact, the intensities measured on these observations can serve as proxies for magnetic activity, due to the strong correlation found between the Ca II K emission and the line-of-sight magnetic flux density. We analyzed three time-series of historic Ca II K observations, specifically those obtained by the digitization of the Arcetri, Kodaikanal, and Mt Wilson spectroheliohram archives. We examined the quality of these data, in order to estimate their value for irradiance studies focusing on time-scales longer than the solar cycle. We employ different processing techniques in order to investigate whether uniform results on the evolution of the solar magnetic field, both in quiet and active regions, can be obtained for the three analyzed series. ——-Session A1.1 Atmosphere Chemistry and Physics (i) Solar Spectral Irradiance Variations and Their Influence on the Earth's Atmosphere

Ermolli, Ilaria; Krivova, Natalie; Solanki, Sami K.

266

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

NASA Astrophysics Data System (ADS)

The solar EUV spectrum has important effects on the upper atmosphere of the Earth and any planet. For a detailed investigation of these effects it is important to have a constistent data series of the EUV spectral irradiance available. Here, we present the reconstruction of the solar EUV irradiance based on PSPT and SOHO/EIT images and along with synthetic spectra calculated for six different coronal features representing the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA tool which allows to identify the features based on a consistent brightness classification for each feature. With the SOLMOD code we then calculate intensity spectra for 10 nm to 100 nm for each of the coronal feature. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed time series is then validated against the spectral irradiance as observed with PROBA2/LYRA. This is an important step towards the understanding of the variations of the solar EUV spectrum and ultimately its detailed effect on the Earth's upper atmosphere.

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

2014-05-01

267

Reconstruction of the solar EUV irradiance from 1996 to 2012 based on SOHO/EIT images  

NASA Astrophysics Data System (ADS)

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

Haberreiter, Margit; Delouille, Veronique; Mampaey, Benjamin; Verbeeck, Cis; Wieman, Seth

2014-05-01

268

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

2006-10-22

269

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

270

What Irradiance Studies Tell Us about Solar/Stellar Convection and Magnetism  

NASA Astrophysics Data System (ADS)

Despite their enormous thermal inertia, many late - type stars exhibit luminosity fluctuations caused by changing photospheric magnetic structures. These fluctuations exist only because of the high heat diffusivity of stellar convection. Were it lower, the dark spots would be surrounded by intense bright rings, as Gene Parker pointed out in 1974. These rings would cancel the spot - induced luminosity dips. Conversely, dark rings around the bright faculae would cancel their positive luminosity contribution. Photometric measurements of this heat diffusivity place independent constraints on solar magnetic diffusivities - a key parameter in dynamo models. Irradiance studies also suggest that the structure of emerging magnetic fields shifts toward lower spatial frequencies with increasing activity. This finding could provide new information on the field source function in dynamo models. Differential and near - IR imaging photometry reveal the decreased temperature gradient of facular magnetic flux tubes and the sunspot- like darkness of their deepest observable layers. Both of these features support current mhd flux tube models. Bolometric imaging measures the wide- band contribution to total irradiance variation, of spot and facular magnetic flux tubes. The remarkably constant solar limb - darkening measured over the past 33 years constrains fluctuations in quiet photospheric temperature gradient and thus, in global convective efficiency over the past three solar cycles. Reconstruction of irradiance variation over past millennia relies on radio- isotope studies. These provide many interesting insights, but they assume that C14 and Be10 are formed only by solar modulation of the galactic cosmic ray flux. This assumption would break down if solar activity and particle fluxes much exceeded levels experienced in cycle 19. Such a "hyperactive” Sun would vary more in its radiative outputs, be dimmer in total irradiance, although brighter in the EUV and X rays. Work is supported by NASA grant NNX09AP96G

Foukal, Peter V.

2010-05-01

271

The Development of Politics in Extraterrestrial Colonies  

NASA Astrophysics Data System (ADS)

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

Sivier, D. J.

272

15. PALEOLIMNOLOGY OF EXTREME COLD TERRESTRIAL AND EXTRATERRESTRIAL ENVIRONMENTS  

E-print Network

15. PALEOLIMNOLOGY OF EXTREME COLD TERRESTRIAL AND EXTRATERRESTRIAL ENVIRONMENTS 475 R. Pienitz, M understanding of life's origins on our planet and other extraterrestrial bodies. Liquid water is essential

Priscu, John C.

273

Photo-recovery of electron-irradiated GaAs solar cells  

NASA Astrophysics Data System (ADS)

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

Meulenberg, Andrew

1995-10-01

274

Photo-recovery of electron-irradiated GaAs solar cells  

NASA Technical Reports Server (NTRS)

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

Meulenberg, Andrew

1995-01-01

275

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

NASA Astrophysics Data System (ADS)

Based on the technological advances and recent growth rates in deployment, solar energy will contribute significantly in the prospective global energy system. However, the intermittent output characteristics of solar energy systems pose a major challenge for the integration of this renewable power resource into the existing power grid. The intra-day solar variability causing output ramps is primarily caused by clouds and aerosols interacting with solar radiation passing through the atmosphere. Recent advances proposed different methods to assess and quantify irradiance fluctuations at the earth's surface. While remote sensing models based on satellite imagery can provide variability data for a vast domain, the temporal resolution is low and show a dearth of validation. In contrast to that, the spatial resolution of ground based instrumentation is limited whereas temporal resolution, precision and accuracy is high. Our validation of satellite based assessment of solar variability with ground truth measurements shows that the satellite based methods provide an accurate picture of variability with half hourly temporal resolution. However, half hourly variability values disregard a large portion of amplitude and frequency of solar variability on shorter timescales. This contribution seeks to investigate the characteristics of different measures of solar irradiance variability, evaluates the accuracy of common variability assessment techniques and finally proposes methods to estimate solar variability in different microclimates under different atmospheric conditions with improved accuracy. Our work shows a novel hybrid approach based on a combination of satellite and sky imager observations to scale down variability values from a 30 minute resolution to a significantly shorter timescale. Current research investigates the applicability and universality of a scaling-law with multiple inputs to derive temporal variability characteristics.

Nonnenmacher, L.; Coimbra, C.

2013-12-01

276

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

277

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

NASA Astrophysics Data System (ADS)

The IHY2007 Whole Heliosphere Interval (WHI) for solar Carrington Rotation 2068 (20 March to 16 April 2008) has been very successful in obtaining a wide variety of solar, heliospheric, and planetary observations during times of solar cycle minimum conditions. One of these efforts is the generation of solar irradiance reference spectra (SIRS) from 0.1 nm to 2400 nm using a combination of satellite and sounding rocket observations. These reference spectra include daily satellite observations from TIMED Solar EUV Experiment (SEE) from 0.1 nm to 116 nm and from Solar Radiation and Climate Experiment (SORCE) instruments from 116 nm to 2400 nm. The EUV range is also improved with higher spectral resolution observations from 6 nm to 105 nm using the prototype SDO EUV Variability Experiment (EVE) aboard a sounding rocket launched on 14 April 2008. The SIRS result is an important accomplishment in that it is the first time in having simultaneous measurements over the full spectral coverage up to 2400 nm and during solar cycle minimum conditions. The SIRS data from 0.1 nm to 2400 nm and in 0.1-nm intervals (on 0.05 nm centers) are available from http://ihy2007.org/WHI/.

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

2008-12-01

278

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

280

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

E-print Network

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

Thomas, Brian C; Snyder, Brock R

2015-01-01

281

Interannual variability in solar ultraviolet irradiance over decadal time scales at latitude 55 degrees south.  

PubMed

Ground-based measurements of solar UV spectral irradiance made from Ushuaia, Argentina at latitude 55 degrees S reveal a large degree of variability among corresponding months of different years over the period from September 1990 through April 1998. The magnitude and wavelength dependence of year-to-year changes in monthly spectral UV-B irradiation are consistent with expectations based on the behavior of column ozone and cloudiness. When combined with satellite measurements of column ozone, a regression model fit to the ground-based data set allows estimates of monthly UV-B irradiation over a time frame of two decades, 1978-1998, during several months of the year. Results show a general increase in ground-level irradiation at 305.0 nm from the end of the 1970s to the early 1990s during calendar months from September through December. This is followed by generally smaller irradiances through the middle to late 1990s for all months except November, where the increase continues through the end of the data record. The long-term variability in monthly irradiation over the time period studied is more complicated than can be described by a simple linear trend. PMID:11783932

Frederick, J E; Manner, V W; Booth, C R

2001-12-01

282

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

283

The Search for Extraterrestrial Intelligence, SETI  

Microsoft Academic Search

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

Philip Morrison; John Billingham; John Wolfe

1977-01-01

284

The search for extraterrestrial intelligence: Telecommunications technology  

Microsoft Academic Search

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

R. Edelson; G. Levy

1977-01-01

285

The search for extraterrestrial intelligence: Telecommunications technology  

Microsoft Academic Search

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

R. E. Edelson; G. S. Levy

1980-01-01

286

The Search for Extraterrestrial Intelligence (SETI)  

Microsoft Academic Search

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

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

1999-01-01

287

The Search for Extraterrestrial Intelligence (SETI)  

Microsoft Academic Search

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

Jill Tarter

2001-01-01

288

Searching for extraterrestrial intelligence - The ultimate exploration  

Microsoft Academic Search

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

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

1977-01-01

289

SAS Honors Seminar 259: Extraterrestrial Life  

E-print Network

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

Baker, Andrew J.

290

SAS Honors Seminar 256: Extraterrestrial Life  

E-print Network

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

Baker, Andrew J.

291

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

NASA Technical Reports Server (NTRS)

The detection of a significant correlation between the solar irradiance, corrected for flux deficit due to sunspots, and both the 205 nm flux and a photometric facular index were examined. A detailed analysis supports facular emission as the more likely source of correlation with the corrected radiance, rather then the error in sunspot correction. A computer program which simulates two dimensional convection in a compressible, stratified medium was investigated. Subroutines to calculate ionization and other thermodynamic variables were also completed.

Petro, L. D.

1986-01-01

292

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

PubMed

Ion irradiation of carbon containing ices produces several effects among which the formation of complex molecules and even refractory organic materials whose spectral color and molecular complexity both depend on the amount of deposited energy. Here results from laboratory experiments are summarized. Their relevance for the formation and evolution of simple molecules and complex organic materials on planetary bodies in the external Solar System is outlined. PMID:11541336

Strazzulla, G

1997-01-01

293

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

Microsoft Academic Search

The ultraviolet narrowband filter radiometer (UV-RAD) designed by the authors to take ground-based measurements of UV solar irradiance, total ozone, and biological dose rate is described, together with the main characteristics of the seven blocked filters mounted on it, all of which have full widths at half maxima that range 0.67 to 0.98 nm. We have analyzed the causes of

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

2006-01-01

294

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

295

Interaction effects of root-zone salinity and solar irradiance on the physiology and biochemistry of Olea europaea  

Microsoft Academic Search

Root-zone salinity stress and high solar irradiance concomitantly occurs in the Mediterranean basin, where Olea europaea is the dominating fruit-tree crop-species. Although the effect of each individual stressor on plant performance has been widely investigated, much less is known on the interaction effects of salinity stress and solar irradiance on the physiology and biochemistry of olive plants. Here we analyzed

Damiano Remorini; Juan Carlos Melgar; Lucia Guidi; Elena Degl’Innocenti; Silvana Castelli; Maria Laura Traversi; Rossano Massai; Massimiliano Tattini

2009-01-01

296

In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions  

Microsoft Academic Search

The performance of triple junction InGaP\\/(In)GaAs\\/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V

R. D. Harris; M. Imaizumi; R. J. Walters; J. R. Lorentzen; S. R. Messenger; J. G. Tischler; T. Ohshima; S. Sato; P. R. Sharps; N. S. Fatemi

2008-01-01

297

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

298

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

PubMed

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

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

2006-06-20

299

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

SciTech Connect

The ultraviolet narrowband filter radiometer (UV-RAD) designed by the authors to take ground-based measurements of UV solar irradiance, total ozone, and biological dose rate is described, together with the main characteristics of the seven blocked filters mounted on it, all of which have full widths at half maxima that range 0.67 to 0.98 nm. We have analyzed the causes of cosine response and calibration errors carefully to define the corresponding correction terms, paying particular attention to those that are due to the spectral displacements of the filter transmittance peaks from the integer wavelength values. The influence of the ozone profile on the retrieved ozone at large solar zenith angles has also been examined by means of field measurements. The opportunity of carrying out nearly monochromatic irradiance measurements offered by the UV-RAD allowed us to improve the procedure usually followed to reconstruct the solar spectrum at the surface by fitting the computed results, using radiative transfer models with field measurements of irradiance. Two long-term comparison campaigns took place, showing that a mean discrepancy of+0.3% exists between the UV-RAD total ozone values and those given by the Brewer no. 63 spectroradiometer and that mean differences of+0.3% and-0.9% exist between the erythemal dose rates determined with the UV-RAD and those obtained with the Brewer no. 63 and the Brewer no. 104 spectroradiometers, respectively.

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

2006-06-20

300

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

301

Cloud Coverage Based on All-Sky Imaging and Its Impact on Surface Solar Irradiance  

SciTech Connect

In Lauder, Central Otago, two all-sky imaging systems have been operated for more than one year measuring the total, opaque, and thin cloud fraction as well as an indicator of whether the sun is obscured by clouds. The data provide a basis for investigating the impact of clouds on the surface radiation field. We aligned the all-sky cloud parameters with measurements of global, direct and diffuse surface solar irradiance over the spectral interval from 0.3 to 3 mm. Here we describe results of ongoing analysis of this data set. As a reference for the magnitude of the cloud influence, clear sky irradiance values are estimated as a simple function of solar zenith angle and Earth-Sun distance. The function is derived from a least-square fit to measurements taken when available cloud images show clear sky situations. Averaged over a longer time period, such as a month, cloud fraction and surface irradiance are clearly negatively correlated. Monthly means in the ratio of the measured surface irradiance to the clear-sky value had a correlation coefficient of about -0.9 with means of cloud fraction for the months July 2000 to June 2001. In the present work we analyze reductions in the surface irradiance and also situations where clouds cause radiation values to exceed the expected clear sky amount. Over one year of observations, 1-minute-average radiation measurements exceeding the expected clear sky value by more than 10% were observed with a frequency of 5%. In contrast, a reduction of more than 10% below estimated clear sky values occurred in 66% of the cases, while clear sky irradiances (measured irradiance within {+-}10% of estimated clear sky value) were observed 29% of the time. Low cloud fractions frequently lead to moderate enhancement, as the sun is often unobscured and the clouds are brighter than the sky that they hide. As cloud fraction increases the sun is likely to be obscured, causing irradiance values to fall well below clear sky values. However, in case of unobscured sun, there is a tendency for strongest enhancements when cloud fractions are highest. Enhancements, especially at high solar zenith angle, are also often observed in association with thin clouds.

Pfister, G.; McKenzie, R. L.; Liley, J. B.; Thomas, A.; Forgan, B. W.; Long, Charles N.

2003-10-31

302

Solar ultraviolet irradiation induces decorin degradation in human skin likely via neutrophil elastase.  

PubMed

Exposure of human skin to solar ultraviolet (UV) irradiation induces matrix metalloproteinase-1 (MMP-1) activity, which degrades type I collagen fibrils. Type I collagen is the most abundant protein in skin and constitutes the majority of skin connective tissue (dermis). Degradation of collagen fibrils impairs the structure and function of skin that characterize skin aging. Decorin is the predominant proteoglycan in human dermis. In model systems, decorin binds to and protects type I collagen fibrils from proteolytic degradation by enzymes such as MMP-1. Little is known regarding alterations of decorin in response to UV irradiation. We found that solar-simulated UV irradiation of human skin in vivo stimulated substantial decorin degradation, with kinetics similar to infiltration of polymorphonuclear (PMN) cells. Proteases that were released from isolated PMN cells degraded decorin in vitro. A highly selective inhibitor of neutrophil elastase blocked decorin breakdown by proteases released from PMN cells. Furthermore, purified neutrophil elastase cleaved decorin in vitro and generated fragments with similar molecular weights as those resulting from protease activity released from PMN cells, and as observed in UV-irradiated human skin. Cleavage of decorin by neutrophil elastase significantly augmented fragmentation of type I collagen fibrils by MMP-1. Taken together, these data indicate that PMN cell proteases, especially neutrophil elastase, degrade decorin, and this degradation renders collagen fibrils more susceptible to MMP-1 cleavage. These data identify decorin degradation and neutrophil elastase as potential therapeutic targets for mitigating sun exposure-induced collagen fibril degradation in human skin. PMID:24023624

Li, Yong; Xia, Wei; Liu, Ying; Remmer, Henriette A; Voorhees, John; Fisher, Gary J

2013-01-01

303

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

304

The impact of solar spectral irradiance variability on middle atmospheric ozone  

NASA Astrophysics Data System (ADS)

This study presents the impact of solar spectral irradiance (SSI) variability on middle atmospheric ozone over the declining phase of solar cycle 23. Two different types of spectral forcing are applied to the Whole Atmosphere Community Climate Model (WACCM) to simulate the ozone response between periods of quiet and high solar activity. One scenario uses the solar proxy reconstructions model from the Naval Research Laboratory (NRLSSI), and the other is based on SSI observations from the Solar Radiation and Climate Experiment (SORCE). The SORCE observations show 3-5 times more variability in ultraviolet (UV) radiation than predicted by the proxy model. The NRLSSI forcing had minimal impact on ozone, however, the higher UV variability from SORCE induced a 4% reduction in ozone concentration above 40 km at solar active conditions. The model result is supported by 8 years (2002-2010) of ozone observations from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The SABER ozone variations have greater similarity with the SORCE SSI model simulations. The model and satellite data suggests that the ozone response is due to enhanced photochemical activity associated with larger UV variability.

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

2011-07-01

305

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

Microsoft Academic Search

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

Eamonn Ansbro; Catherine Overhauser

2001-01-01

306

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

Microsoft Academic Search

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

Fred H. Thaheld

2006-01-01

307

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

Microsoft Academic Search

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

T. Joseph W. Lazio

2004-01-01

308

Search for organics in extraterrestrial environments by in situ gas chromatography analysis  

Microsoft Academic Search

Many organic molecules are present in interstellar clouds and might be carried to the early Earth by comets and meteorites during the heavy bombardment period in the first few hundred million years of the solar system. It has been suggested that extraterrestrial organic material may well represent an important part of the organic material available for the origin of life.

C. Rodier; R. Sternberg; C. Szopa; A. Buch; M. Cabane; F. Raulin

2004-01-01

309

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

Microsoft Academic Search

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

R. MICHEL; I. LEYA

310

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

311

First performance results of two novel spectroradiometers developed for fast scanning of solar spectra UV irradiance  

NASA Astrophysics Data System (ADS)

Two recently developed different types of fast spectroradiometers measuring solar UV irradiance have been compared in a field campaign: i) the UV spectroradiometer on filter model basis (UV-SPRAFIMO) and ii) the modified version of the spectroradiometer SPECTRO 320D by Instrument Systems. The all-weather UV-SPRAFIMO instrument combines a UV filter radiometer with 5 narrow-band (FBHM ~ 2.0 to 2.5 nm) filters centered within +/- 0.01 nm at 303.5, 309.0, 314.5, 327.0 and 387.0 nm, and an advanced neural network-based model. It allows up to 5 measurements per second to be taken that are averaged within time intervals between 5 and 30 s. The neural networks model that is embedded in the PC-based processing software converts the 5 measured irradiances into a full spectrum from 280 to 450 nm at small wavelength steps (>= 0.05 nm). These spectra can be convoluted with user-defined slit function and integrated to broad-band and action-spectra-weighted irradiance values. Users can access the data stored in the internal data logger by a serial RS232 interface or by a modem and display them on a PC-based Graphical User Interface. The spectroradiometer SPECTRO320D consists of a grating double monochromator with a cooled (-20°C) PMT receiver. The modified instrument version run by DWD uses a Schreder type cosine diffuser that directs the solar global irradiance via quartz fiber optics onto the spectroradiometer's entrance slit. The spectroradiometer used at the campaign was installed in a thermostatted (22 +/- 0.02)°C aluminum box. The modified instrument version performs a spectral scan over the whole UV region in two subsequent parts, with a lower speed in the UV-B than in the UV-A to account for the exponential changes of solar irradiance with increasing wavelengths in the UV-B and for the almost linear change in the UV-A region. In the configuration applied in the comparison, i.e. wavelength steps of 0.2 nm within the scan range from 290 nm to 450 nm, the resulting scan time of the SPECTRO 320D was 23 s. The two spectroradiometers, which both have been absolutely calibrated in the DWD lab using FEL 1000 W halogen lamps traceable to the German Physikalisch-Technische Bundesanstalt (PTB), were used in a field campaign at Izana (Tenerife Island) at a height of 2409 m to compare measured spectral and integral values of solar irradiance. Results of that comparison and the instruments" characteristics revealed under those special field conditions will be discussed.

Feister, Uwe; Kaifel, Anton K.; Grewe, Rolf-Dieter; Kaptur, Jasmine; Reutter, Oliver; Wohlfart, Michael; Gericke, Klaus

2003-11-01

312

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 of the atmosphere and the earth's cloud cover on a space-and-time continuous basis with a ground resolution

Perez, Richard R.

313

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

314

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

315

A simple analytical formula to compute clear sky total and photosynthetically available solar irradiance at the ocean surface  

NASA Technical Reports Server (NTRS)

A simple but accurate analytical formula was developed for computing the total and the photosynthetically available solar irradiances at the ocean surface under clear skies, which takes into account the processes of scattering by molecules and aerosols within the atmosphere and of absorption by the water vapor, ozone, and aerosols. These processes are parameterized as a function of solar zenith angle, aerosol type, atmospheric visibility, and vertically integrated water-vapor and ozone amounts. Comparisons of the calculated and measured total and photosynthetically available solar irradiances for several experiments in tropical and mid-latitude ocean regions show 39 and 14 Wm/sq m rms errors (6.5 and 4.7 percent of the average measured values) on an hourly time scale, respectively. The proposed forumula is unique in its ability to predict surface solar irradiance in the photosynthetically active spectral interval.

Frouin, Robert; Lingner, David W.; Gautier, Catherine; Baker, Karen S.; Smith, Ray C.

1989-01-01

316

Solar surgery: remote fiber optic irradiation with highly concentrated sunlight in lieu of lasers  

NASA Astrophysics Data System (ADS)

Highly concentrated sunlight has the power density required by many laser fiber optic surgical procedures. Thanks to recent progress in optical design, the means now exist to concentrate solar radiation in dielectrics to levels that exceed those at the surface of the sun, and to efficiently deliver it remotely. Since surgical power requirements are typically only several watts, the solar collection unit can be miniaturized. Although generating uncollimated radiation, solar surgery can serve as a low-cost alternative to laser fiber optic systems in treatments where wide-angle emissions are preferable. Even nominally monochromatic treatments such as photodynamic therapy can use highly concentrated sunlight because the power density within a typical wavelength window for these treatments (around 0.004 micrometer) is adequate to the task. Scheduling of solar surgery should not pose difficulties in clear climates. Solar concentration is performed in two stages: a paraboloidal reflector dish and a second-stage nonimaging concentrator. Concentrated irradiation would be transported via low-attenuation silica optical fibers to the operating room. With power delivery typically emanating from a disk of diameter 0.6 mm, the dish diameter would be in the vicinity of 200 mm with an even smaller system depth. The system could deliver a flux density as high as 70 W mm-2 for contact surgery and 30 W mm-2 for noncontact surgery. Aside from lasers, sunlight is uniquely suited to the task, in contrast to today's available light sources.

Feuermann, Daniel; Gordon, Jeffrey M.

1998-10-01

317

NIEL Dose Dependence for Solar Cells Irradiated with Electrons and Protons  

E-print Network

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

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

2014-02-10

318

Simulation of solar-cycle response in tropical total column ozone using SORCE irradiance  

NASA Astrophysics Data System (ADS)

Total column ozone (XO3) abundance in Earth's atmosphere is intimately related to atmospheric chemistry and dynamics. Understanding the solar-cycle modulations of XO3 helps distinguish anthropogenic perturbations from natural variability during the ozone recovery. Here, the solar-cycle signal of tropical XO3 in the Whole Atmosphere Community Climate Model (WACCM) model has been examined using solar spectral irradiance (SSI) estimated from the Naval Research Laboratory (NRL) solar model and that from recent satellite measurements observed by the Solar Radiation and Climate Experiment (SORCE). Four experiments have been conducted with NRL/SORCE SSI and climatological/realistic sea surface temperatures and ice, and all other variability is fixed. In the tropical region 24° S-24° N, using the SORCE SSI as a model input leads to a solar-cycle response of ~5.4 DU/100F10.7, which is ~2 times of that obtained using NRL SSI. The results are slightly different in the presence of El Niño/Southern Oscillation (ENSO) when realistic SST/ice is used, but these differences are within the regression uncertainty of ~0.6 DU/100F10.7. The solar-cycle responses simulated using SORCE SSI agree with those obtained from the merged TOMS/SBUV satellite observations. Using NRL SSI as a model input results in solar-cycle responses that are closer to the ground-based observations, although the accuracy of the latter is limited by the number of stations in the tropics. In all model experiments, the tropical distribution of the solar-cycle response is constant to within ~0.5 DU/100F10.7, which is of the same order as the regression uncertainty. The spatial structures of the regression uncertainty are shown to be correlated with ENSO in the Pacific region. The solar-cycle response obtained using SORCE SSI implies a maximum change in lower stratospheric temperature of ~0.8 K. This may lead to significant impacts on the model solar-cycle responses in atmospheric circulation, precipitation and other hydrological variables that are important for the climate change.

Li, K.-F.; Jiang, X.; Liang, M.-C.; Yung, Y. L.

2012-01-01

319

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

320

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

NASA Astrophysics Data System (ADS)

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

Dick, S. J.

321

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

NASA Astrophysics Data System (ADS)

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

Dick, Steven J.

322

Extraterrestrial Studies Using Nuclear Interactions  

NASA Technical Reports Server (NTRS)

Cosmogenic nuclides were used to study the recent histories of the aubrite Norton County and the pallasite Brenham using calculated production rates. Calculations were done of the rates for making cosmogenic noble-gas isotopes in the Jovian satellite Europa by the interactions of galactic cosmic rays and especially trapped Jovian protons. Cross sections for the production of cosmogenic nuclides were reported and plans made to measure additional cross sections. A new code, MCNPX, was used to numerically simulate the interactions of cosmic rays with matter and the subsequent production of cosmogenic nuclides. A review was written about studies of extraterrestrial matter using cosmogenic radionuclides. Several other projects were done. Results are reviewed here with references to my recent publications for details.

Reedy, Robert C.

2003-01-01

323

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

324

UV testing of solar cells: Effects of antireflective coating, prior irradiation, and UV source  

NASA Astrophysics Data System (ADS)

Short-circuit current degradation of electron irradiated double-layer antireflective-coated cells after 3000 hours ultraviolet (UV) exposure exceeds 3 percent; extrapolation of the data to 10(exp 5) hours (11.4 yrs.) gives a degradation that exceeds 10 percent. Significant qualitative and quantitative differences in degradation were observed in cells with double- and single-layer antireflective coatings. The effects of UV-source age were observed and corrections were made to the data. An additional degradation mechanism was identified that occurs only in previously electron-irradiated solar cells since identical unirradiated cells degrade to only 6 +/- 3 percent when extrapolated 10(exp 5) hours of UV illumination.

Meulenberg, A.

1993-05-01

325

Puzzles of Biochemistry of Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

Biological exclusion principles are briefly explained. The author would like to discuss whether or not the exclusion principle can also be applied on biochemistry and molecular biology of extraterrestrial life.

Oshima, T.

2013-11-01

326

Unidentified flying objects and extraterrestrial life  

NASA Astrophysics Data System (ADS)

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

Marsh, Carole

327

Estimating aerosol characteristics from solar irradiance measurements at an urban location in southeastern Spain  

NASA Astrophysics Data System (ADS)

cloudless conditions aerosols are the main atmospheric components responsible for direct effects on solar radiation. Measurements of aerosol optical properties along with simultaneous measurements of solar irradiances (global -G- and diffuse -D-) were recorded at an urban site (Granada, Spain) to characterize the radiative effect of atmospheric aerosols from 2006 to 2008. The selection of cloudless conditions was made considering cases with 0 oktas. To avoid cloud contamination, a restricted data set with clearness index larger than 0.65 and maximum D of 200 W/m2 was used. The analysis was performed evaluating G, D, and IN (direct normal irradiance) and the ratios between them in association with aerosol optical depth (AOD) at 675 nm. Results show an aerosol forcing efficiency of -279 ± 21 W/m2 per unit of AOD at 675 nm at 15° solar zenith angle and a maximum value in June for monthly mean aerosol radiative forcing of -23 ± 7 W/m2. Large dependency was shown of the ratios D/G and D/IN which increased with increasing AOD, while IN/G decreased. On the other hand, the ratio D/IN was the most reliable parameter to estimate AOD with a coefficient of determination of 0.94; the empirical relationship obtained was validated using an independent data set obtaining 2.5% mean bias deviation and 13.5% root-mean-square deviation. This relationship constitutes an alternative tool for estimating AOD from routine irradiance measurements available from numerous radiometric stations worldwide.

Foyo-Moreno, I.; Alados, I.; Antón, M.; Fernández-Gálvez, J.; Cazorla, A.; Alados-Arboledas, L.

2014-02-01

328

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

329

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

330

Coproduction of volatiles and metals from extraterrestrial materials  

NASA Technical Reports Server (NTRS)

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

Lewis, John S.

1991-01-01

331

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

332

Direct-normal solar irradiance measurements and turbidity coefficient evaluation in central Spain.  

NASA Astrophysics Data System (ADS)

In order to study the characteristics of solar direct radiation and the atmospheric turbidity in Valladolid, Spain, global, diffuse and direct irradiance data were recorded from May 2010 to December 2011, with a frequency of 10 minute. Measurements used were taken by the Energy and Atmosphere Group (http://www3.uva.es/renova), University of Valladolid, Spain at the Solar Radiometric Station (41,81°N 4.93°W, 840m a.s.l.) located on the Atmosphere Researcher Centre, Villalba de los Alcores, Valladolid, Spain. Sensors were installed in a Sun tracker (Solys 2, Kipp & Zonen) that blocks direct solar radiation using a shadow ball. The system consists of two pyranometers CMP-21 and one pyrheliometer CHP-1 (Kipp & Zonen), respectively. Based on these measurements, the characteristics of direct solar irradiance data were evaluated in order to know the main statistical parameters of the distribution. Angström turbidity coefficient values, beta, were estimated from direct solar irradiance and clear sky conditions. The beta coefficient values were obtained from MODIS satellite instrument, and the aerosol optical depth values, AOD(550nm), were evaluated. The turbidity coefficient beta shows seasonal variation, with higher values in summer (< 0.15) and lower in winter (< 0.05). It could be due to high temperatures in summer and less rainy days which would induce more atmospheric turbidity, increasing vertical convection and particles enhancement. The scattered graph of aerosol optical depth from satellite and the obtained from Angström expression has been plotted. The slope presents a value around the unity, 0.96, and the correlation coefficient shows a value of 0.6 . It was observed that turbidity coefficients increased in April 2011, and in order to now the origin the change, air masses trajectories, deduced from HYSPLIT model (http://ready.arl.noaa.gov/HYSPLIT.php) were studied. From the results it has been obtained that a situation of low pressures in the Atlantic Portuguese coast and high pressure in the North of Spain induced the movement of dust from Sahara desert into the Iberian Peninsula.

Bllbao, Julia; Román, Roberto; Miguel, Argimiro

2013-04-01

333

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

334

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

335

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

336

A new solar irradiance calibration from 3295 A to 8500 A derived from absolute spectrophotometry of Vega  

NASA Technical Reports Server (NTRS)

By imaging sunlight diffracted by 20- and 30-micron diameter pinholes onto the entrance aperture of a photoelectric grating scanner, the solar spectral irradiance was determined relative to the spectrophotometric standard star Vega, observed at night with the same instrument. Solar irradiances are tabulated at 4 A increments from 3295 A to 8500 A. Over most of the visible spectrum, the internal error of measurement is less than 2 percent. This calibration is compared with earlier irradiance measurements by Neckel and Labs (1984) and by Arvesen et al. (1969) and with the high-resolution solar atlas by Kurucz et al. The three calibrations agree well in visible light but differ by as much as 10 percent in the ultraviolet.

Lockwood, G. W.; Tueg, H.; White, N. M.

1992-01-01

337

IR Spectroscopy and Photo-Chemistry of Extraterrestrial Ices  

NASA Technical Reports Server (NTRS)

Dense molecular clouds from which planetary systems form and the outer Solar System are both cold environments dominated by ices. Infrared (IR) spectroscopy is used to probe these ices, but the IR absorptions of molecules depend on the conditions. As a result appropriate lab data is needed to correctly fit spectra of extraterrestrial ices. Such fits have shown that most of these ices are composed primarily of H2O, but also contain 1-10 percent of other simple molecules such as CO2, CO, CH4, & NH3;. We shall present near IR spectra of ice mixtures of relevance to icy outer Solar System bodies and show that they still hold surprises, such as the Cheshire cat-like CO2 (2v3) overtone near 2.134 micrometers (4685 cm-1) that is absent from spectra of pure CO2 but present in H2O-CO2 mixtures.

Bernstein, Max P.; Mastrapa, Rachel; Elsila, Jamie; Sandford, Scott

2005-01-01

338

A search strategy for SETI - The search for extraterrestrial intelligence  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

339

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

340

Measuring spectral diffuse solar irradiance with non-cosine flat-plate diffusers  

SciTech Connect

In spectral diffuse solar irradiance measurements, when diffusing devices used are neither perfectly Lambertian nor have an ideal cosine response, significant errors may spoil the collected data. An optical method permits the determination of a spectral correction factor (SCF) which fully compensates for the diffusers` imperfection when the sky radiance is isotropic. A study of the errors introduced when using such a isotropic SCF in anisotropic radiance conditions is presented for two common flat-plate diffusers fitted with a shadow-ring or a tracking disk. The wavelength band explored is 0.29 - 0.90 {mu}m and the clear sky radiance model used is Kittler`s. The relevance of several diffuse irradiance spectra measured on clear sky days with isotropic SCF is analysed by comparison with Brine-Iqbal model spectra and total diffuse measurements. A remarkable coherence is found for small solar zenith angles when using a tracking disk and a diffuser with an isotropic SCF smaller than 1.2. 17 refs., 7 figs., 2 tabs.

Casiniere, A.A. de; Cabot, T. [Universite Joseph Fourier, Grenoble (France)] [Universite Joseph Fourier, Grenoble (France); Benmansour, S. [U.S.T.H.B., El-Alia Bab-Ezzouar (Algeria)] [U.S.T.H.B., El-Alia Bab-Ezzouar (Algeria)

1995-03-01

341

Fast measurements of solar spectral UV irradiance—first performance results of two novel spectroradiometers  

NASA Astrophysics Data System (ADS)

Short spectral scan times of preferably less than 1 min in the UV region are an important prerequisite for modern spectroradiometers to reflect short-term solar irradiance radiation variations that can occur as a result of fast changes in cloud cover and/or cloud optical depth. Two different types of fast measuring spectroradiometers for solar UV irradiance are compared in a first field campaign: (1) the UV spectroradiometer on filter model basis (UV-SPRAFIMO) and (2) the modified version of the spectroradiometer SPECTRO 320D by Instrument Systems. The UV-SPRAFIMO instrument combines a filter radiometer with five narrowband (FWHM?2.0 to 2.7 nm) filters centered at fixed wavelengths in the UV-B and UV-A regions with an advanced neural network-based model. Up to 5 measurements/s can be taken concurrently in the five wavelength channels. After averaging the measurements over preselectable time intervals, the measured irradiances are converted by the neural network model into a full spectrum from 280 to 450 nm at arbitrary wavelength steps (>=0.05 nm). The SPECTRO 320D spectroradiometer consists of a grating double monochromator with a cooled photomultiplier tube (PMT) receiver. The instrument version run by Deutscher Wetterdienst (DWD) is thermostatted and equipped with a Schreder type cosine diffuser as the entrance optics. A spectral scan from 290 to 450 nm with a selected 0.2-nm wavelength step takes less than 30 s. The two spectroradiometers are used in a field campaign at Izana (Tenerife Island) at a height of 2440 m above sea level (ASL) to compare measured spectral and integral values of solar irradiance. Results of that comparison and the instruments' characteristics are discussed. This first field comparison shows that due to the fast measurements regime, cloud effects on the measured spectra can be appreciably reduced. The campaign shows an acceptable agreement between the spectra measured by both instruments. It also reveals some issues for further improvements of the instrument design.

Feister, Uwe; Kaifel, Anton K.; Grewe, Rolf-Dieter; Kaptur, Jasmine; Reutter, Oliver; Wohlfart, Michael; Gericke, Klaus

2005-04-01

342

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

343

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

SciTech Connect

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

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

2014-04-24

344

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

345

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

346

Extraterrestrial intelligence - An observational approach  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

347

Extraterrestrial Organic Compounds in Meteorites  

NASA Astrophysics Data System (ADS)

Many organic compounds or their precursorsfound in meteorites originated in the interstellar or circumstellarmedium and were later incorporated intoplanetesimals during the formation of thesolar system. There they either survivedintact or underwent further processing tosynthesize secondary products on themeteorite parent body.The most distinct feature of CI and CM carbonaceouschondrites, two typesof stony meteorites, is their high carbon content(up to 3% of weight), either in theform of carbonates or of organic compounds. The bulkof the organic carbon consistsof an insoluble macromolecular material with a complexstructure. Also present is asoluble organic fraction, which has been analyzedby several separation and analyticalprocedures. Low detection limits can be achievedby derivatization of the organicmolecules with reagents that allow for analysisby gas chromatography/massspectroscopy and high performance liquidchromatography. The CM meteoriteMurchison has been found to contain more than70 extraterrestrial amino acids andseveral other classes of compounds includingcarboxylic acids, hydroxy carboxylicacids, sulphonic and phosphonic acids, aliphatic,aromatic and polar hydrocarbons,fullerenes, heterocycles as well as carbonylcompounds, alcohols, amines and amides.The organic matter was found to be enriched indeuterium, and distinct organiccompounds show isotopic enrichments of carbon andnitrogen relative to terrestrialmatter.

Botta, Oliver; Bada, Jeffrey L.

348

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

349

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

350

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

351

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

PubMed

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

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

2014-02-01

352

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

353

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

354

Solar Activity and Irradiance Studies with Ca II Spectroheliograms: Potential and Problems  

NASA Astrophysics Data System (ADS)

Various observatories around the globe carried out synoptic full-disk observations of the Sun since the beginning of the 20th century. The archives created by these observations, especially those including Ca II spectroheliograms, have the potential of providing far more detailed information on solar activity than the indices usually used to study activity variations, solar cycle and irradiance changes. However, these data suffer significantly from various problems including numerous defects in the photographic plates, missing or inaccurate calibration of the blackening curve, changes in the positioning of the exit slit with respect to the spectral line and variable seeing. Here we discuss the quality of images obtained by the digitization of three historic Ca II K time series, specifically those stored by the Arcetri, Kodaikanal and Mt Wilson Observatories. The aim of this work is to evaluate the potential value of these data for studies of solar activity and variability. It also shows the importance of the detailed and accurate image processing technique, in order to obtain uniform and trustable results from images coming from different historic archives.

Ermolli, I.; Tlatov, A.; Solanki, S. K.; Krivova, N. A.; Singh, J.

2007-05-01

355

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

SciTech Connect

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

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

2014-02-03

356

CONTROL ID: 1484811 TITLE: Infrared Spectroscopy of Extraterrestrial Materials  

E-print Network

CONTROL ID: 1484811 TITLE: Infrared Spectroscopy of Extraterrestrial Materials AUTHORS (FIRST NAME are measuring the infrared spectra of a wide range of extraterrestrial materials in the laboratory. The goals

Rossman. George R.

357

STABLE ISOTOPIC RESPONSE TO THE LATE EOCENE EXTRATERRESTRIAL IMPACT EVENTS  

E-print Network

STABLE ISOTOPIC RESPONSE TO THE LATE EOCENE EXTRATERRESTRIAL IMPACT EVENTS by AIMEE E PUSZ A thesis to the Late Eocene Extraterrestrial Impact Events by AIMEE ELIZABETH PUSZ Thesis Director: Dr. Kenneth G

358

Device performance and lifetime of polymer:fullerene solar cells with UV-ozone-irradiated hole-collecting buffer layers.  

PubMed

We report the influence of UV-ozone irradiation of the hole-collecting buffer layers on the performance and lifetime of polymer:fullerene solar cells. UV-ozone irradiation was targeted at the surface of the poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) layers by varying the irradiation time up to 600 s. The change of the surface characteristics in the PEDOT:PSS after UV-ozone irradiation was measured by employing optical absorption spectroscopy, photoelectron yield spectroscopy, and contact angle measurements, while Raman and X-ray photoelectron spectroscopy techniques were introduced for more microscopic analysis. Results showed that the UV-ozone irradiation changed the chemical structure/composition of the surface of the PEDOT:PSS layers leading to the gradual increase of ionization potential with irradiation time in the presence of up-and-down variations in the contact angle (polarity). This surface property change was attributed to the formation of oxidative components, as evidenced by XPS and Auger electron images, which affected the sheet resistance of the PEDOT:PSS layers. Interestingly, device performance was slightly improved by short irradiation (up to 10 s), whereas it was gradually decreased by further irradiation. The short-duration illumination test showed that the lifetime of solar cells with the UV-ozone irradiated PEDOT:PSS layer was improved due to the protective role of the oxidative components formed upon UV-ozone irradiation against the attack of sulfonic acid groups in the PEDOT:PSS layer to the active layer. PMID:22038984

Lee, Seungsoo; Nam, Sungho; Lee, Hyena; Kim, Hwajeong; Kim, Youngkyoo

2011-11-18

359

Advanced Curation of Current and Future Extraterrestrial Samples  

NASA Technical Reports Server (NTRS)

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

Allen, Carlton C.

2013-01-01

360

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

361

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

362

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

363

An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis  

E-print Network

An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis Todd A. Surovella an impact by an extraterrestrial body, an event that had devastating ecological consequences for humans any results of the Firestone et al. study and find no support for Younger Dryas extraterrestrial

Holliday, Vance T.

364

Absence of extraterrestrial 3 He in PermianTriassic  

E-print Network

Absence of extraterrestrial 3 He in Permian­Triassic age sedimentary rocks K.A. Farley a,*, P. Ward the Permian­Triassic boundary at Opal Creek, Canada, to determine whether high extraterrestrial helium concentrations are associated with a possible extinction- inducing impact event at this time. No extraterrestrial

Mukhopadhyay, Sujoy

365

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

366

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

367

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 gained from the exploitation of existing Earth observation technologies and will take advantage of the enhanced capabilities of the new Meteosat Second Generation (MSG) satellites. The expected quality

Heinemann, Detlev

368

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

PubMed

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

Ciesla, Fred J; Sandford, Scott A

2012-04-27

369

Solar/Stellar Irradiance Comparison Experiment (SOLSTICE) on the Upper Atmosphere Research Satellite (UARS)  

NASA Technical Reports Server (NTRS)

A final report on the operational activities related to the UARS Solar Stellar irradiance Comparison Experiment (SOLSTICE) is presented. Scientific activities of SOLSTICE has also been supported. The UARS SOLSTICE originated at the University of Colorado in 1981. One year after the UARS launch in 1991, the operations and research support activities for SOLSTICE were moved to the High Altitude Observatory (HAO) of the National Center for Atmospheric Research (NCAR). The SOLSTICE program continued at HAO with the National Science Foundation, and after four years, it was moved once again back to the University of Colorado. At the University after 1997 this subject grant was issued to further extend the operations activities from July 2001 through September 2002. Although this is a final report for one particular activity, in fact the SOLSTICE operations activity -first at the University, then at HAO, and now again at the University -has continued in a seamless fashion.

Rottman, Gary J.; Woods, Thomas N.; London, Julius; Ayres, Thomas R.

2003-01-01

370

Organic Synthesis via Irradiation and Warming of Ice Grains in the Solar Nebula  

NASA Technical Reports Server (NTRS)

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

Ciesla, Fred J.; Sanford, Scott A.

2012-01-01

371

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(exp -2) 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.

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

2000-01-01

372

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 around 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 W/sq m 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.

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

2000-01-01

373

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

374

The Use of Meteosat Second Generation Satellite Data Within A New Type of Solar Irradiance Calculation Scheme  

NASA Astrophysics Data System (ADS)

1-University of Oldenburg, 2-University of Appl. Sciences Magdeburg, 3-Ecole des Mines de Paris, 4-University of Bergen, 5-Ecole Nationale des Travaux Publics de l'Etat, 6-University of Geneva, 7-Instituto Tecnologico de Canarias, 8-Fraunhofer Institute for Solar Energy Systems, 9-German Aerospace Center Geostationary satellites such as Meteosat provide cloud information with a high spatial and temporal resolution. Such satellites are therefore not only useful for weather fore- casting, but also for the estimation of solar irradiance since the knowledge of the light reflected by clouds is the basis for the calculation of the transmitted light. Additionally an the knowledge of atmospheric parameters involved in scattering and absorption of the sunlight is necessary for an accurate calculation of the solar irradiance. An accurate estimation of the downward solar irradiance is not only of particular im- portance for the assessment of the radiative forcing of the climate system, but also necessary for an efficient planning and operation of solar energy systems. Currently, most of the operational calculation schemes for solar irradiance are semi- empirical. They use cloud information from the current Meteosat satellite and clima- tologies of atmospheric parameters e.g. turbidity (aerosols and water vapor). The Me- teosat Second Generation satellites (MSG, to be launched in 2002) will provide not only a higher spatial and temporal resolution, but also the potential for the retrieval of atmospheric parameters such as ozone, water vapor and with restrictions aerosols. With this more detailed knowledge about atmospheric parameters it is evident to set up a new calculation scheme based on radiative transfer models using the retrieved atmospheric parameters as input. Unfortunately the possibility of deriving aerosol in- formation from MSG data is limited. As a cosequence the use of data from additional satellite instruments ( e.g. GOME/ATSR-2) is neeeded. Within this presentation a new type of the solar irradiance calculation scheme is de- scribed. It is based on the integrated use of a radiative transfer model (RTM), whereas the information of the atmospheric parameters retrieved from satellites (MSG and GOME/ATSR-2) will be used as input for the RTM. First comparisons between calcu- lated and measured solar irradiance are presented. The improvements linked with the usage of the new calculation scheme are discussed, taking into account the benefits and limitations of the new method and the MSG satellite.

Mueller, R. W.; Beyer, H. G.; Cros, S.; Dagestad, K. F.; Dumortier, D.; Ineichen, P.; Hammer, A.; Heinemann, D.; Kuhlemann, R.; Olseth, J. A.; Piernavieja, G.; Reise, C.; Schroedter, M.; Skartveit, A.; Wald, L.

375

Mat. Res. Soc. Symp. Proc. Vol. 668 @ 2001 Materials Research Society Influence of proton irradiation and development of flexible CdTe solar cells on polyimide  

E-print Network

are highly stable under proton flux. Flexible and lightweight solar cells were developed in a superstrate will describe the photovoltaic properties of irradiated solar cells. Development of flexible and lightweight substrates. CdTe solar cells on metal foils exhibit an efficiency of ~5% [9-10]. Here, we describe

Romeo, Alessandro

376

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

377

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

EPA Science Inventory

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

378

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

379

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

380

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

381

A Short Duration of the Cretaceous-Tertiary Boundary Event: Evidence from Extraterrestrial Helium3  

Microsoft Academic Search

Analyses of marine carbonates through the interval 63.9 to 65.4 million years ago indicate a near-constant flux of extraterrestrial helium-3, a tracer of the accretion rate of interplanetary dust to Earth. This observation indicates that the bolide associated with the Cretaceous-Tertiary (K-T) extinction event was not accompanied by enhanced solar system dustiness and so could not have been a member

S. Mukhopadhyay; K. A. Farley; A. Montanari

2001-01-01

382

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

Microsoft Academic Search

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

Toshimichi Shirai; Tomoaki Oyama; Hiroshi Imai; Shinsuke Abe

2004-01-01

383

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

Microsoft Academic Search

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

Fred H. Thaheld

2006-01-01

384

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

385

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

NASA Astrophysics Data System (ADS)

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 of 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, although this might be possible by the inclusion of other external constraints. Our methodology has the potential, using wider datasets, to provide better understanding of both variations in SSI and the atmospheric response.

Ball, William T.; Mortlock, Daniel J.; Egerton, Jack S.; Haigh, Joanna D.

2014-09-01

386

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

387

Investigation of the effect of contrails on global irradiance and solar energy production  

NASA Astrophysics Data System (ADS)

In the present study we investigate the effect of contrails on global shortwave radiation and on Photovoltaic module performance. This investigation is performed using continuous hemispherical fish eye photographs of the sky, diffuse and direct shortwave measurements and short circuit current measurements of a-Si, c-Si and CdTe PV modules. These measurements have been performed at the solar observatory Kanzelhöhe (1540 m.a.s.l) located in the southern part of Austria during a period of one and half year. The time resolution of the measurements is one minute, which allows to accurately follow the formation-eventually the disappearance- or the movement of the contrails in the sky. Using the fish eye photographs we identified clear sky days with a high contrail persistence. We especially look at situations where the contrails were shading the sun. Results show that contrails shading the sun may reduce the global radiation by up to 60%. In general we however observe that during days with a high contrail persistence the diffuse irradiance is slightly increased. Finally a statistic of the contrail persistence during the period of measurement is presented and conclusions as to the relevance for the solar energy production are drawn.

Weihs, Philipp; Rennhofer, Marcus; Baumgartner, Dietmar; Wagner, Jochen; Laube, Wolfgang; Gadermaier, Josef

2013-04-01

388

Induction of UV photoproducts and DNA damage by solar simulator UV irradiation  

SciTech Connect

The recent increased incidence of skin cancer and the depletion of the ozone layer has increased interest in the ultraviolet (UV) component of natural sunlight and its role in the induction of skin cancer. Previous research on UV radiation has concentrated on UVC (254nm) but, as only UVB and UVA are present in natural sunlight, its relevance is unknown. We have investigated the induction of two forms of direct DNA damage - the pyrimidine dimer and the (6-4) photoproduct - in human DNA repair deficient XP-G (Xeroderma pigmentosum group G) lymphoblastoid cells following exposure to simulated sunlight. As exposure to natural sunlight is highly variable, a solar simulator lamp was used which is known to mimic natural sunlight at midday in Central Europe. Cells were irradiated on ice to minimise DNA repair and the relative induction of pyrimidine dimers and (6-4) photoproducts was measured using specific monoclonal antibodies and a computer assisted image analysis system. A time dependent increase in both cyclobutane dimer and (6-4) photoproduct antibody binding sites was seen. The increases in pyrimidine dimer and (6-4) photoproduct antibody binding sites differed to that reported with natural sunlight in the UK but was similar to that seen with a similar solar simulator lamp.

Wolfreys, A.; Henderson, L. [Unilever Research, Sharnbrook, Bedford (United Kingdom); Clingen, P. [Univ. of Sussex, Falmer, Brigthon (United Kingdom)

1997-10-01

389

Impact of aerosol on surface reaching solar irradiance over Mohal in the northwestern Himalaya, India  

NASA Astrophysics Data System (ADS)

The present study, for the first time during 2007, is focused to examine the impact of aerosols on surface reaching solar irradiance over Mohal (31.9°N, 77.12°E, 1154 m amsl) in the northwestern part of the Indian Himalaya. The study also aims to estimate shortwave aerosol radiative forcing (SWARF) and its effect on regional climate. The multi-wavelength solar radiometer (MWR) is used to measure aerosol optical depth (AOD) over a wider spectrum, i.e. ultraviolet, visible and near-infrared. The AOD is obtained by analyzing the data from MWR following the Langley technique. The radiative transfer model is used along with Optical Properties of Aerosols and Clouds model to estimate the SWARF. Aerosol shows a great efficiency to reduce substantial fraction of energy from the surface reaching direct solar beam, i.e. 154 W m-2 ?m-1 per unit AOD at 0.5 ?m. The SWARF at the surface, top of the atmosphere and the atmosphere is estimated to be -18.5±1.7, +0.6±3.7 and +19.1±3.1 W m-2, respectively. The large SWARF at the surface stood during the summer (April-July), while small during the monsoon (August-September). Moderate SWARF is obtained in the autumn (October-November) and winter (December-March). The study estimates a notable extinction in incoming solar radiation relatively with lower atmospheric heating from 0.41 to 0.73 K day-1. The potential effect of aerosol is found relatively higher on high aerosol loading days. On these days, the lower atmospheric heating increases by a factor 1.8 (during dust events) and 1.7 (during biomass burning). This study concludes that aerosols produce significant reduction in incoming solar radiation with substantial increase in lower atmospheric heating, leading to a remarkable effect on the atmospheric stability. In addition, as a subject of future interest, the present study has also important implications on the atmospheric circulation and regional climate.

Guleria, Raj Paul; Kuniyal, Jagdish Chandra; Dhyani, Pitamber Prasad; Joshi, Ranjan; Sharma, Nand Lal

2014-02-01

390

Isotopic, Chemical and Mineralogical Investigation's of Extraterrestrial Materials  

NASA Technical Reports Server (NTRS)

During the grant period we have concentrated on the following main topics: 1. Enstatite meteorites and original heterogeneity of Mn-53 distribution in the solar nebula. We have completed our studies of the enstatite chondrites. 2. Processes of planetary differentiation. We have completed our study of silicate clasts from the mesosiderite Vaca Muerta and found that the global Mn/Cr fractionation event that established mantle source reservoirs on the parent body of the Vaca Muerta silicate clasts occurred approx. 2 Ma after a similar event on the howardite-eucrite-diogenite (HED) parent body. 3. Carbonaceous chondrites. Much effort has been devoted during the last three years to the investigation of this important class of meteorites. 4. Early solar system timescales. Based on the studies of the Mn-53 - Cr-53 isotope system in various meteorites and using results obtained with other isotope chronometers we constructed an absolute time-scale for events in the early solar system. 5.Unusual meteorites. We have studied the anomalous pallasite Eagle Station. 6. The chromium isotopic composition as a tracer for extraterrestrial material on Earth. Based on the observed difference in the Cr-53/Cr-52 ratios between Earth and the other solar system objects we developed a method for detecting cosmic materials on Earth using the Cr-53/Cr-52 ratio as a tracer.

Lugmair, G. W.

2003-01-01

391

Recent concepts in missions to Mars - Extraterrestrial processes  

NASA Technical Reports Server (NTRS)

This paper presents some recent concepts in Mars Sample Return (MSR) missions that utilize extraterrestrial resources. The concepts examined include the power and energy needs of this mission. It is shown that solar energy is not especially attractive. Radioisotopic power generator and a Rankine cycle use are seen to be viable options. Quantitative estimates, taking into consideration state-of-the-art and projected technologies indicate that the power/energy per se is not critical to the mission - but reliability is. Hence, various modern options for the components of the power generation and utilization are discussed. The dramatic savings in Shuttle (or other) vehicle launches are quantitatively plotted. The basic system that is discussed here is the production of hydrocarbon (methane) fuel and oxygen from Martian atmosphere. For the simplest mission, it is seen that earth-carried methane burned with oxygen produced on site provides the best system.

Ramohalli, K. N.; Ash, R. L.; Lawton, E. A.; French, J. R.; Frisbee, R. H.

1986-01-01

392

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

393

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.

394

Extraterrestrial Life: Processes, Implications, and Applications.  

ERIC Educational Resources Information Center

Provided are background materials relating the study of extraterrestrial life to common biological principles. A history of the creation of the sun and earth is included, as well as a summary of one current theory regarding the origin of life on earth. Relationships are identified regarding possible origins of life on other planets. Factors…

Molyson, Joseph T.

395

Strategy for the search for extraterrestrial intelligence  

Microsoft Academic Search

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

N. S. Kardashev

1979-01-01

396

The Search for ExtraTerrestrial Intelligence  

Microsoft Academic Search

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

J. Tarter

1998-01-01

397

NASA contemplates radio Search for Extraterrestrial Intelligence  

Microsoft Academic Search

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

R. Sheaffer

1976-01-01

398

SETI [Search for ExtraTerrestrial Intelligence  

Microsoft Academic Search

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

B. M. Oliver

1994-01-01

399

SETI: Search for ExtraTerrestrial Intelligence  

E-print Network

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

Walter, Frederick M.

400

The Search for Extraterrestrial Intelligence (SETI)  

E-print Network

#12;The Search for Extraterrestrial Intelligence (SETI) Our goals for learning · What is the Drake Estimate: flife ~ 0.5 - 1 #12;NHP � flife � fciv � fnow How many planets with life develop intelligence planets have intelligent life now? Major extinction events have occurred in the past #12;NHP � flife

Shirley, Yancy

401

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

NASA Technical Reports Server (NTRS)

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

Li, S. S.

1981-01-01

402

Analysis of Ca II K images aiming to determine long-term trends in solar irradiance variability  

NASA Astrophysics Data System (ADS)

The change in radiative output of the Sun on time scales longer than a day is attributed to the variability in solar surface magnetic fields. Direct irradiance measurements are only available for less than four decades. To reconstruct long term trends in solar total and spectral irradiance, proxies of solar surface magnetism like sunspot, facular and network areas are needed. Currently, sunspot records alone are used for this purpose, from which the deduction of facular and network areas is rather indirect. Historical records of full disk images of the Sun taken in the Ca II K spectral line (393.3 nm) have the potential to provide far more direct information about the distribution and evolution of faculae and network elements. The latter appear as bright regions in the Ca II K spectroheliograms and their intensity is correlated with the magnetic field strength of the features on the solar surface. Solar full disk images in the Ca II K line have been recorded since the beginning of the 20th century at a number of solar observatories such as at Arcetri (Italy), Mount Wilson(California, US) and Kodaikanal (India). The images are available in digitized archives that contain the data processed for standard instrumental calibrations. To utilize these records for irradiance studies, the next step is to identify the bright magnetic features from the images using feature recognition techniques. We test different feature identification methods which are first applied to a set of recent images from the PSPT instrument at the Osservatorio Astronomico di Roma, taken during three periods characterized by high, medium and low levels of activity. Then the performance of these methods to historical images from Arcetri, Mt. Wilson and Kodaikanal archives is tested. The results will be presented and discussed here.

Kar, Anuradha; Ermolli, Ilaria; Krivova, Natalie; Solanki, Sami

2013-04-01

403

Corroboration for the influence of a component of solar irradiance on subsurface radon signals  

NASA Astrophysics Data System (ADS)

Rn-222 occurs at highly varying levels as a trace component in subsurface air (geogas). This high variability is traced by alpha and gamma activity due to the decay of radon and its progeny. Nuclear radiation from radon in geogas and in experiments using air+radon within a confined volume exhibits systematic temporal variations. These variations are composed of periodic and non-periodic signals spanning several orders of magnitude in time - from annual to daily and sub-daily durations. Analysis of extensive data sets from three key sites 200 km apart in the arid desert of southern Israel [1-3] and from a 5-year experiment using alpha and gamma detectors [4] demonstrate that the periodic variations, observed to a depth of >100 meters, are related to an above surface driver probably due to a component of solar irradiance. Insight was also derived from the long term variations in the geological and the experimental time series [5], indicated by the occurrence of multi-year variations, and clear semiannual and ternary annual signals which are in addition to the annual periodicity. New confirmations are based on recognizing further cyclic phenomena, some of which are not linked with Earth related periodicities. A likehood analysis of the alpha and gamma time series in a long-term experiment is performed. A Combined Power Statistic formed from the gamma, alpha-H and alpha-L sensors inside the experimental tank shows that the time series of the gamma radiation contains an annual periodicity as well as a clear semi-annual and possibly a ternary-annual periodicity. The same analysis also resolves additional periodicities in the frequency range of 10-15 yr-1 in the gamma time series which are indicative of a relationship to rotation of the sun around its axis [6]. Observation of solar periodicities in the temporal pattern of the nuclear radiation of radon is a significant independent substantiation for the notion of the influence of a component in solar irradiance. An independent confirmation of the solar effect in the experimental data is obtained by observing day time and night time patterns. "Specgrams" of the power as a function of frequency and hour of day show that the peak of the annual periodicity occurs at daytime while the semi-annual and solar periodicities are seen to be prominent at night. This is interpreted to indicate a differentiation in the nuclear radiation from radon as a function of rotation of Earth. - i.e. when Earth faces the sun and when the sun is completely obstructed. This feature is also demonstrated using Continuous Wavelet Transform (CWT) analysis on separate time series composed of day-time and night-time measurements. Applying the CWT analysis yields different frequency-time variation patterns for day-time and night-time measurements in the experimental data. This confirms the utilization of the CWT analysis for detecting the phenomena. Using the CWT analysis tool the day- and night-time difference in radon time series is also detected at subsurface geological sites from Israel, Tenerife and Italy. These sites are from different geological and geophysical scenarios, different elevations and span depths from several meters to around 1000m below the surface. New multi disciplinary prospects for the research are indicated in terms of a) the radioactive behavior of radon in above surface and subsurface air, b) an above surface geophysical driver for this behavior and, c) the influence of a component of solar irradiation. 1. Steinitz, G., O. Piatibratova, and S. M. Barbosa, 2007. Radon daily signals in the Elat Granite, southern Arava, Israel, J. Geophys. Res., 112, B10211, doi:10.1029/2006JB004817. 2. Steinitz, G., Piatibratova, O., 2010a. Radon signals in the Gavnunim intrusion, Makhtesh Ramon, Israel. Geophys. J. Int. 180, 651-665. 3. Steinitz, G. and Piatibratova, O., 2010. Radon signals at the Roded site, Southern Israel, Solid Earth, 1, 99-109, doi:10.5194/se-1-99-2010. 4. Steinitz, G., Piatibratova, O., Kotlarsky, P., 2011. Possible effect of solar tides on radon signals. Journal of

Steinitz, G.; Piatibratova, O.; Kotlarsky, P.; Sturrock, P.; Maritn, C.

2012-04-01

404

On the relationship between cardboard burning in a sunshine recorder and the direct solar irradiance.  

NASA Astrophysics Data System (ADS)

Since the end of XIX century, the Campbell-Stokes recorder (CSR) has been the instrument used to measure the insolation (hours of sunshine during per day). Due to the large number of records that exist worldwide (some of them extending over more than 100 years), valuable climatic information can be extracted from them. There are various articles that relate the insolation with the cloudiness and the global solar irradiation (Angstrom-Prescott type formulas). Theoretically, the insolation is defined as the number of hours that direct solar irradiance (DSI) exceeds 120 W/m2, thus corresponding to the total length of the burning in the bands. The width of the burn has not been well studied, so the aim of this research is to relate this width, first with the DSI and then, with other variables. The research was carried out in Girona (NE Spain) for a period extending since February 2011. A CSR from Thies Clima and a pyrheliometer from Kipp&Zonen were used to measure insolation and the direct solar irradiance. Other meteorological variables were also stored for the study. For each band, we made two independent measurements of the width of the burn every 10 minutes: first, we measured directly the width of the perforated portion of the burn; second, we measured the width of the burn after applying a digital image process that increases the contrast of the burn. The burn in a band has a direct relationship with the DSI. Specifically, correlation coefficients of the perforation width and the burning width with DSI were 0.838 and 0.864 respectively. However, we found that there are times when despite of DSI is as high as 400 W/m2 (i.e. much greater than 120 W/m2), there is no burn in the band. Contrarily, sometimes a burn occurs with almost no DSI. Furthermore, a higher DSI does not always correspond to a wider burn of the band. Because of this, we consider that characteristics of band burns must also depend on other meteorological variables (temperature, humidity...). The physical characteristics of the heliograph and of the cardboard from which the bands are made may also have an important role in this relationship. The method was applied to a limited series of bands so the results and conclusions are preliminary. The first conclusion is the lack of accuracy that has the threshold value of 120 W/m2 and the difficulty of giving a single value of this threshold. The sudden changes and intermittent weather conditions, combined with the poor temporal resolution of the measure of the burn width, reduce the correlation between burn and DSI. For further research aimed at the study of the behavior of the insolation due to the changing concentration of aerosols in the atmosphere, we need to increase the number of burned sunshine bands and to describe with more accuracy the limitations of heliographs.

Sanchez, A.; Calbó, J.; González, J. A.

2012-04-01

405

Extraterrestrial organic matter: a review  

NASA Technical Reports Server (NTRS)

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

Irvine, W. M.

1998-01-01

406

Extraterrestrial organic matter: a review.  

PubMed

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. PMID:9742722

Irvine, W M

1998-10-01

407

Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations  

NASA Astrophysics Data System (ADS)

Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. Aims: We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI. Methods: SATIRE-S ascribes variation in solar irradiance on timescales greater than a day to photospheric magnetism. The solar spectrum is reconstructed from the apparent surface coverage of bright magnetic features and sunspots in the daily data using the modelled intensity spectra of these magnetic structures. We cross-calibrated the various data sets, harmonizing the model input so as to yield a single consistent time series as the output. Results: The model replicates 92% (R2 = 0.916) of the variability in the PMOD TSI composite including the secular decline between the 1996 and 2008 solar cycle minima. The model also reproduces most of the variability in observed Lyman-? irradiance and the Mg II index. The ultraviolet solar irradiance measurements from the UARS and SORCE missions are mutually consistent up to about 180 nm before they start to exhibit discrepant rotational and cyclical variability, indicative of unresolved instrumental effects. As a result, the agreement between model and measurement, while relatively good below 180 nm, starts to deteriorate above this wavelength. As with earlier similar investigations, the reconstruction cannot reproduce the overall trends in SORCE/SIM SSI. We argue, from the lack of clear solar cycle modulation in the SIM record and the inconsistency between the total flux recorded by the instrument and TSI, that unaccounted instrumental trends are present. Conclusions: The daily solar irradiance time series is consistent with observations from multiple sources, demonstrating its validity and utility for climate models. It also provides further evidence that photospheric magnetism is the prime driver of variation in solar irradiance on timescales greater than a day.

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

2014-10-01

408

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

409

Diffusion length variation in 0. 5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells  

SciTech Connect

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

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

1993-04-01

410

Stochastic model to describe atmospheric attenuation from yearly global solar irradiation  

NASA Astrophysics Data System (ADS)

A new stochastic model to describe atmospheric attenuation from yearly global solar irradiation has been developed and implemented. The proposed model takes into account the consideration that the whole of all attenuating elements can be thought of as a population where the higher the number of individuals the lesser the clearness index. Thus, the inverse of the clearness index is considered as the variable of a stochastic process. From the proposed master equation as starting point, the new model is characterized by transition rates (assessed from a growing parameter - G - and a decreasing parameter - D) which depend mainly on the climatological characteristics at each location. In this sense, different regions with an attenuation level calculated from the yearly global irradiation have been established using the Köppen-Geiger climate classification as a first approach. The model parameters G and D have been determined for different regions using the inverse of the clearness index as variable. The probability density function obtained after the application of the stochastic model for each climate zone shows how the index mode increases from the zones with lower levels of attenuation to those with higher levels of attenuation. This result confirms the proposed null hypothesis related to the use of the inverse of the clearness index as an attenuation population indicator. The fit between the empirical data and the data provided for the model is good enough according to a Kolmogorov-Smirnov test with a significance level of 0.05. Nevertheless, it is necessary to slightly modify the climate zones of Köppen-Geiger initial classification for a better explanation of the atmospheric attenuation. This climate zones modification can be considered as an additional result.

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

2015-02-01

411

A general model to predict individual exposure to solar UV by using ambient irradiance data.  

PubMed

Excessive exposure to solar ultraviolet (UV) is the main cause of skin cancer. Specific prevention should be further developed to target overexposed or highly vulnerable populations. A better characterisation of anatomical UV exposure patterns is however needed for specific prevention. To develop a regression model for predicting the UV exposure ratio (ER, ratio between the anatomical dose and the corresponding ground level dose) for each body site without requiring individual measurements. A 3D numeric model (SimUVEx) was used to compute ER for various body sites and postures. A multiple fractional polynomial regression analysis was performed to identify predictors of ER. The regression model used simulation data and its performance was tested on an independent data set. Two input variables were sufficient to explain ER: the cosine of the maximal daily solar zenith angle and the fraction of the sky visible from the body site. The regression model was in good agreement with the simulated data ER (R(2)=0.988). Relative errors up to +20% and -10% were found in daily doses predictions, whereas an average relative error of only 2.4% (-0.03% to 5.4%) was found in yearly dose predictions. The regression model predicts accurately ER and UV doses on the basis of readily available data such as global UV erythemal irradiance measured at ground surface stations or inferred from satellite information. It renders the development of exposure data on a wide temporal and geographical scale possible and opens broad perspectives for epidemiological studies and skin cancer prevention. PMID:24496216

Vernez, David; Milon, Antoine; Vuilleumier, Laurent; Bulliard, Jean-Luc; Koechlin, Alice; Boniol, Mathieu; Doré, Jean F

2015-01-01

412

A Solid-Phase Chemical Actinometer for Snowpack Solar Irradiation Measurements  

NASA Astrophysics Data System (ADS)

Research over the past decade has established the importance of polar snow as a medium for chemical processing of atmospheric species; recent laboratory studies have demonstrated the photochemical transformation of anthropogenic organic contaminants in frozen water matrices. In order to investigate the role of snow photochemistry under environmental conditions, field researchers need methods for determining the intensity of light available at the surface and also penetrating the snowpack as a function of depth. While theoretical models exist for light penetration, they rely on a number of parameters relating to the formation and history of the snowpack that field researchers are unlikely to have knowledge of; this makes direct in-situ measurements desirable. Conventional liquid-phase actinometers are of limited use in polar environments where low ambient temperatures may interfere with diffusion-controlled processes - the freezing of aqueous solutions being an extreme case - resulting in varying quantum yields. A solid-phase actinometer system based on the well-studied photoisomerization of o-nitrobenzaldehyde (oNB) has been developed as an alternative device for the measurement of solar UV light intensity. Sample films consisting of oNB incorporated in a polymethylmethacrylate matrix are exposed to light and the extent of oNB loss from the film's surface is determined by ATR-IR spectroscopy. Films are rugged enough to allow deployment in environments that are impractical to access with bulkier electronic instruments, and small enough to allow precise placement and positioning without disturbing the bulk of the snowpack under consideration. Trial measurements made in late- thaw snowpacks near Barrow, Alaska in June 2007 demonstrate the usefulness of this technique for determining relative light intensity as a function of snowpack depth. The technique could readily be extended to other environments where solar irradiance cannot readily be measured by instrumental approaches.

Rowland, G. A.; Grannas, A. M.

2007-12-01

413

Impact of differences in the solar irradiance spectrum on surface reflectance retrieval with different radiative transfer codes  

NASA Technical Reports Server (NTRS)

Surface reflectance retrieval from imaging spectrometer data as acquired with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has become important for quantitative analysis. In order to calculate surface reflectance from remotely measured radiance, radiative transfer codes such as 5S and MODTRAN2 play an increasing role for removal of scattering and absorption effects of the atmosphere. Accurate knowledge of the exo-atmospheric solar irradiance (E(sub 0)) spectrum at the spectral resolution of the sensor is important for this purpose. The present study investigates the impact of differences in the solar irradiance function, as implemented in a modified version of 5S (M5S), 6S, and MODTRAN2, and as proposed by Green and Gao, on the surface reflectance retrieved from AVIRIS data. Reflectance measured in situ is used as a basis of comparison.

Staenz, K.; Williams, D. J.; Fedosejevs, G.; Teillet, P. M.

1995-01-01

414

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

NASA Astrophysics Data System (ADS)

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 between 0.29 and 4.0 microns, with a resolution that varies from 0.005 to 0.1 micron. Absorption by water vapor, ozone and the uniformly mixed gases is included, as are both scattering and absorption by atmospheric aerosols, which are modeled with simple wavelength-dependent optical depth, single scattering albedo and asymmetry parameter functions. Comparisons are presented of the model results with spectral irradiance and radiance computed by other more sophisticated models and with measurements from both ground-based and satellite instruments. The reasonable accuracy and simplicity of the model make it suitable for a number of applications, especially those involving tests of the sensitivity of spectral irradiances or radiances to variations in water vapor, ozone and various aerosol parameters.

Justus, C. G.; Paris, M. V.

1985-03-01

415

Analytical SuperSTEM for extraterrestrial materials research  

SciTech Connect

Electron-beam studies of extraterrestrial materials with significantly improved spatial resolution, energy resolution and sensitivity are enabled using a 300 keV SuperSTEM scanning transmission electron microscope with a monochromator and two spherical aberration correctors. The improved technical capabilities enable analyses previously not possible. Mineral structures can be directly imaged and analyzed with single-atomic-column resolution, liquids and implanted gases can be detected, and UV-VIS optical properties can be measured. Detection limits for minor/trace elements in thin (<100 nm thick) specimens are improved such that quantitative measurements of some extend to the sub-500 ppm level. Electron energy-loss spectroscopy (EELS) can be carried out with 0.10-0.20 eV energy resolution and atomic-scale spatial resolution such that variations in oxidation state from one atomic column to another can be detected. Petrographic mapping is extended down to the atomic scale using energy-dispersive x-ray spectroscopy (EDS) and energy-filtered transmission electron microscopy (EFTEM) imaging. Technical capabilities and examples of the applications of SuperSTEM to extraterrestrial materials are presented, including the UV spectral properties and organic carbon K-edge fine structure of carbonaceous matter in interplanetary dust particles (IDPs), x-ray elemental maps showing the nanometer-scale distribution of carbon within GEMS (glass with embedded metal and sulfides), the first detection and quantification of trace Ti in GEMS using EDS, and detection of molecular H{sub 2}O in vesicles and implanted H{sub 2} and He in irradiated mineral and glass grains.

Bradley, J P; Dai, Z R

2009-09-08

416

Isotopic anomalies in extraterrestrial grains.  

PubMed

Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars. PMID:11541324

Ireland, T R

1996-03-01

417

Gene Expression in the Scleractinian Acropora microphthalma Exposed to High Solar Irradiance Reveals Elements of Photoprotection and Coral Bleaching  

PubMed Central

Background The success of tropical reef-building corals depends on the metabolic co-operation between the animal host and the photosynthetic performance of endosymbiotic algae residing within its cells. To examine the molecular response of the coral Acropora microphthalma to high levels of solar irradiance, a cDNA library was constructed by PCR-based suppression subtractive hybridisation (PCR-SSH) from mRNA obtained by transplantation of a colony from a depth of 12.7 m to near-surface solar irradiance, during which the coral became noticeably paler from loss of endosymbionts in sun-exposed tissues. Methodology/Principal Findings A novel approach to sequence annotation of the cDNA library gave genetic evidence for a hypothetical biosynthetic pathway branching from the shikimic acid pathway that leads to the formation of 4-deoxygadusol. This metabolite is a potent antioxidant and expected precursor of the UV-protective mycosporine-like amino acids (MAAs), which serve as sunscreens in coral phototrophic symbiosis. Empirical PCR based evidence further upholds the contention that the biosynthesis of these MAA sunscreens is a ‘shared metabolic adaptation’ between the symbiotic partners. Additionally, gene expression induced by enhanced solar irradiance reveals a cellular mechanism of light-induced coral bleaching that invokes a Ca2+-binding synaptotagmin-like regulator of SNARE protein assembly of phagosomal exocytosis, whereby algal partners are lost from the symbiosis. Conclusions/Significance Bioinformatics analyses of DNA sequences obtained by differential gene expression of a coral exposed to high solar irradiance has revealed the identification of putative genes encoding key steps of the MAA biosynthetic pathway. Revealed also by this treatment are genes that implicate exocytosis as a cellular process contributing to a breakdown in the metabolically essential partnership between the coral host and endosymbiotic algae, which manifests as coral bleaching. PMID:21103042

Starcevic, Antonio; Dunlap, Walter C.; Cullum, John; Shick, J. Malcolm; Hranueli, Daslav; Long, Paul F.

2010-01-01

418

Century-Long Monitoring of Solar Irradiance and Earth's Albedo Using a Stable Scattering Target in Space  

E-print Network

An inert sphere of a few meters diameter, placed in a special stable geosynchronous orbit in perpetuo, can be used for a variety of scientific experiments. Ground-based observations of such a sphere, "GeoSphere", can resolve very difficult problems in m