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1

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

National Technical Information Service (NTIS)

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

C. Riordan

1987-01-01

2

Extraterrestrial spectral solar irradiance data for modeling spectral solar irradiance at the earth's surface  

SciTech Connect

This report describes the extraterrestrial (air mass zero, AMO) spectral solar irradiance data used by the Solar Energy Research Institute's Resource Assessment Branch in models to calculate spectral solar irradiance at the earth's surface. The report contains tables and graphs of the AMO spectrum updated by the World Radiation Center in Daveos, Switzerland, in 1985.

Riordan, C.

1987-05-01

3

Remeasuring the extraterrestrial solar spectral irradiance  

NASA Astrophysics Data System (ADS)

We will measure the solar spectral irradiance by deploying a CCD-array solar spectrograph to a high altitude favorable site, as part of a self-contained autonomous system with a calibration system using a monochromator and absolute photodiode "trap detectors." Data will be reduced using Langley extrapolation (and in the stronger absorption bands methods similar to Reagan-Brugge fitting), to yield the solar output free of atmospheric absorption. This measurement system will substantially improve the accuracy of the field measurements by making the instrument continuously self-calibrating against a local absolute standard in the range 400 - 900 nm. In the ranges 360 - 400 nm and also 900 - 1100 the trap detectors are not an absolute standard, but serve as a very reproducible transfer standard from an irradiance scale to be taken from either NIST lamps, or more recently-introduced detectors with calibrated efficiencies. We expect an absolute accuracy of 0.3% for solar-spectrum determination in the range 400 to 900 nm, not including the O2 band at 760 nm, and the H2O bands at 820 and 940 nm. In the 360 - 400 nm domain we may be able to extend trap-detector quantum efficiency to allow an accuracy better than a secondary irradiance transfer, otherwise this domain and the range 900 to 1100 nm will have an accuracy of ? 1 %. The extrapolations in the strong-absorption bands will have an increased uncertainty which can be estimated from the statistics of the data. We describe the instrument and self-calibration methadologies and design.

Harrison, Lee; Berndt, Jerry L.; Kiedron, Piotr W.

2003-11-01

4

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

5

Searching for Extraterrestrial Technologies Within Our Solar System  

NASA Astrophysics Data System (ADS)

We speculate about possible cosmic exploration by extraterrestrial civilizations using interstellar smart probes. We call attention to some emerging technologies that may be used for interstellar exploration. We estimate that advanced civilizations may already have these technologies and may be using them to contact their galactic neighbors. We explore some observational consequences of these contacting strategies.

Tough, Allen; Lemarchand, Guillermo A.

2004-06-01

6

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

7

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

Microsoft Academic Search

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

David A. Blank; Chih Wu

1995-01-01

8

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

Microsoft Academic Search

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

Robert C. Reedy

2000-01-01

9

A high-resolution near-infrared extraterrestrial solar spectrum derived from ground-based Fourier transform spectrometer measurements  

NASA Astrophysics Data System (ADS)

A detailed spectrally resolved extraterrestrial solar spectrum (ESS) is important for line-by-line radiative transfer modeling in the near-IR. Very few observationally based high-resolution ESS are available in this spectral region. Consequently, the theoretically calculated ESS by Kurucz has been widely adopted. We present the CAVIAR (Continuum Absorption at Visible and Infrared Wavelengths and its Atmospheric Relevance) ESS, which is derived using the Langley technique applied to calibrated observations using a ground-based high-resolution Fourier transform spectrometer (FTS) in atmospheric windows from 2000 to 10,000 cm-1 (1-5 µm). There is good agreement between the strengths and positions of solar lines between the CAVIAR and the satellite-based Atmospheric Chemistry Experiment-FTS ESS, in the spectral region where they overlap, and good agreement with other ground-based FTS measurements in two near-IR windows. However, there are significant differences in the structure between the CAVIAR ESS and spectra from semiempirical models. In addition, we found a difference of up to 8% in the absolute (and hence the wavelength-integrated) irradiance between the CAVIAR ESS and that of Thuillier et al., which was based on measurements from the Atmospheric Laboratory for Applications and Science satellite and other sources. In many spectral regions, this difference is significant, because the coverage factor k = 2 (or 95% confidence limit) uncertainties in the two sets of observations do not overlap. Because the total solar irradiance is relatively well constrained, if the CAVIAR ESS is correct, then this would indicate an integrated "loss" of solar irradiance of about 30 W m-2 in the near-IR that would have to be compensated by an increase at other wavelengths.

Menang, Kaah P.; Coleman, Marc D.; Gardiner, Tom D.; Ptashnik, Igor V.; Shine, Keith P.

2013-06-01

10

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

11

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

Microsoft Academic Search

Ionising radiation is an energy source capable of generating and altering complex organic matter. A full understanding of the radiolytic formation and evolution of organic matter is essential to appreciate the budget of organic chemicals that exist in cometary and interstellar ices, carbonaceous meteorites, and to understand the results of analyses of irradiated extraterrestrial organic matter, such as that in

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

2006-01-01

12

SORCE Solar Irradiance Data Products  

Microsoft Academic Search

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

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

2008-01-01

13

Solar Spectral Irradiance and Climate  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

14

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

15

Spectral solar irradiance data sets for selected terrestrial conditions  

NASA Astrophysics Data System (ADS)

Direct normal and global spectral solar irradance data sets are presented for selected terrestrial conditions, along with a brief review of previous data sets. The new data sets presented cover the 0.305 micron to 4.045 microns region and were generated with the rigorous BRITE Monte Carlo radiative transfer code, the revised Neckel and Labs extraterrestrial solar spectrum, the U.S. standard atmosphere model, and a rural aerosol model. The data for the 2.45 microns to 4.045 microns region were taken from existing ASTM standards (E891-82 and E892-82). Tabular and graphical data presentations include irradiance versus wavelength, photon flux density versus wavelength, and photon flux density versus photon energy.

Hulstrom, R.; Brid, R.; Riordan, C.

1985-12-01

16

Diffuse and global solar spectral irradiance under cloudless skies  

SciTech Connect

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

Brine, D.T.; Iqbal, M.

1982-01-01

17

Updates to ISO 21348 (determining solar irradiances)  

NASA Astrophysics Data System (ADS)

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

Tobiska, W. Kent

2012-07-01

18

Total solar irradiance trend during solar cycles 21 and 22  

SciTech Connect

Results from Activity Cavity Radiometer Irradiance Monitor (ACRIM) experiments show an upward trend in total solar irradiance of 0.036 percent per decade between the minima of solar cycles 21 and 22. The trend follows the increasing solar activity of recent decades and, if sustained, could raise global temperatures. Trends of total solar irradiance near this rate have been implicated as causal factors in climate change on century to millennial time scales. 20 refs., 2 figs., 2 tabs.

Willson, R.C. [Columbia Univ., Altadena, CA (United States)

1997-09-26

19

Solar Irradiance Variability and Climate  

NASA Astrophysics Data System (ADS)

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

Solanki, Sami K.; Krivova, Natalie A.; Haigh, Joanna D.

2013-08-01

20

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

21

The demography of extraterrestrial civilizations  

Microsoft Academic Search

Studies carried out within the last ten years on the nature and distribution of extraterrestrial intelligent life are reviewed. Arguments for the absence of intelligent life in the Galaxy based on the assumption that at least some of these would have engaged in colonization and for the presence of colonies of extraterrestrials in some undiscovered location in the solar system

J. Billingham

1981-01-01

22

Contributions of the solar ultraviolet irradiance to the total solar irradiance during large flares  

Microsoft Academic Search

The solar X-ray radiation varies more than other wavelengths during flares; thus solar X-ray irradiance measurements are relied upon for detecting flare events as well as used to study flare parameters. There is new information about the spectral and temporal variations of flares using solar irradiance measurements from NASA's Solar Radiation and Climate Experiment (SORCE) and the Thermosphere, Ionosphere, Mesosphere,

Thomas N. Woods; Greg Kopp; Phillip C. Chamberlin

2006-01-01

23

Historical Variations in Solar UV Irradiance  

NASA Astrophysics Data System (ADS)

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

DeLand, M. T.

2011-12-01

24

Solar Irradiance Short Wave Radiation Users Guide.  

National Technical Information Service (NTIS)

Solar irradiance for short wave radiation (400-700 nm) at the sea surface can be calculated using inputs obtained from satellite systems and model estimates. The short wave solar irradiance is important for estimating the surface heating that occurs in th...

P. Martinolich R. A. Arnone

1995-01-01

25

Variations in total solar irradiance during solar cycle 22  

Microsoft Academic Search

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

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

1996-01-01

26

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

27

Solar Extreme Ultraviolet Irradiance During Solar Cycle Minimum  

NASA Astrophysics Data System (ADS)

There have been very few measurements of the solar cycle minimum irradiance in the extreme ultraviolet (EUV: 1- 120 nm) range. The solar activity is currently very low, perhaps at the solar cycle minimum this spring, and the solar EUV irradiance for these conditions will be measured by satellite instruments and a sounding rocket payload. The satellite instruments are aboard NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and Solar Radiation and Climate Experiment (SORCE) satellites. The NASA 36.240 sounding rocket payload is being launched from White Sand Missile Range in April 2008 to provide an underflight calibration for the satellite instruments. The primary instrument on the rocket payload is the prototype EUV Variability Experiment (EVE) that will measure the solar irradiance from 0.1-105 nm with 0.1 nm resolution. The other rocket instrument is the prototype X-Ray Photometer System (XPS), similar to the flight versions on TIMED and SORCE. This rocket XPS has been modified to contain X-ray channels with the same bandpasses as the GOES X-ray Sensor (XRS). While the primary goal of this rocket launch is to provide a underflight calibration for TIMED Solar EUV Experiment (SEE), the other important goal is to obtain the most accurate solar EUV irradiance spectrum during solar cycle minimum. This solar minimum irradiance measurement will also contribute to the April 2008 Whole Heliosphere Interval (WHI) campaign titled "Characterizing the Energetics and Dynamics of the Quiet Sun" (lead: Scott McIntosh).

Chamberlin, P. C.; Woods, T. N.; Eparvier, F. G.

2008-05-01

28

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

29

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

30

Climatology of Solar Irradiance on Inclined Surfaces; Part 1.  

National Technical Information Service (NTIS)

The following solar input variables were measured from March 1979 to October 1979 in Cabauw in the Netherlands: (1) the global solar irradiance, with an Eppley pyranometer, for five different orientations; (2) the direct solar irradiance on a surface perp...

W. H. Slob D. E. Brethouwer C. Den Ouden

1981-01-01

31

Determination of Potential Direct Beam Solar Irradiance.  

National Technical Information Service (NTIS)

Procedures are presented for calculating potential direct beam solar irradiance, corrected for latitude, azimuth and inclination of slope, date, and time of day. Equations are structured to permit the user to calculate instantaneous or total daily irradia...

M. R. Kaufmann J. D. Weatherred

1982-01-01

32

Active-region evolution and solar rotation variations in solar UV irradiance, total solar irradiance, and soft X ray  

Microsoft Academic Search

Variations in the solar UV spectral irradiance, the total solar irradiance, and solar soft X ray emission over days and weeks are analyzed by using concurrent measurements from the NUMBUS 7 and GOES satellites. The UV variations at wavelengths (160-400 nm) of interest to ozone photochemistry and the physics of the middle atmosphere are emphasized. The nonflare variations studied are

R. F. Donnelly; D. F. Heath; J. L. Lean

1982-01-01

33

Active-Region Evolution and Solar Rotation Variations in Solar UV Irradiance, Total Solar Irradiance, and Soft X Rays  

Microsoft Academic Search

Variations in the solar UV spectral irradiance, the total solar irradiance, and solar soft X ray emission over days and weeks are analyzed by using concurrent measurements from the NIMBUS 7 and GOES satellites. The UV variations at wavelengths (160-400 nm) of interest to ozone photochemistry and the physics of the middle atmosphere are emphasized. The nonflare variations studied are

R. F. Donnelly; D. F. Heath; J. L. Lean

1982-01-01

34

Rotational Variability in Ultraviolet Solar Spectral Irradiance  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

35

The LASP Interactive Solar IRradiance Datacenter (LISIRD)  

NASA Astrophysics Data System (ADS)

LASP has created an online resource for combined solar irradiance datasets from the SORCE, TIMED, UARS, and SME missions. The LASP Interactive Solar IRradiance Datacenter (LISIRD) not only provides unified access to the individual datasets, but also combines them for ease of use by scientists, educators, and the general public. In particular, LISIRD makes available composite spectra and time series. The TIMED SEE, SORCE SOLSTICE, and SORCE SIM instruments produce spectra that together cover the solar spectrum from 1 to 2700 nm. Through the LISIRD interface, the user can get data that bridges the various missions in both wavelength and time. LISIRD also hosts data products of interest to the space weather community. They have slightly different needs than the atmospheric modelers that are the typical users of irradiance data. For space weather applications, high time cadence and near real-time data delivery are key. For these users, we make our observations available shortly after spacecraft contact, and append the observations to a single data file which they can retrieve using anonymous ftp every few hours. The third component of LISIRD is the Solar Physical Radiation Model (SPRM) results of Fontenla et al. It provides a model of current solar activity, the synthetic spectral irradiance, and tools that permit one to model the solar activity source of the spectral irradiance variations.

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

2005-12-01

36

Cosmogenic nuclides in extraterrestrial materials  

SciTech Connect

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.

Vogt, S.; Herzog, G.F.; Reedy, R.C. (Rutgers Univ., New Brunswick, NJ (USA) Los Alamos National Lab., NM (USA))

1990-08-01

37

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

38

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

39

Diamond, Graphitic and Amorphous Carbons in Primitive Extraterrestrial Solar System Materials. (Abstract Only).  

National Technical Information Service (NTIS)

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 variou...

F. J. M. Rietmeijer

1990-01-01

40

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

41

Ionospheric Change and Solar EUV Irradiance  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

42

A New Look at Solar Irradiance Variation  

NASA Astrophysics Data System (ADS)

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

Foukal, Peter

2012-08-01

43

Long-Term Solar Irradiance Variability: 1984-1989 Observations.  

National Technical Information Service (NTIS)

Long-term variability in the total solar irradiance has been observed in the Earth Radiation Budget Experiment (ERBE) solar monitor measurements. The monitors have been used to measure the irradiance from the Earth Radiation Budget Satellite (ERBS) and th...

R. B. Lee

1990-01-01

44

Subduction of solar-type noble gases from extraterrestrial dust: constraints from high-pressure low-temperature metamorphic deep-sea sediments  

NASA Astrophysics Data System (ADS)

Solar-type helium (He) and neon (Ne) in the Earth’s mantle were suggested to be the result of solar-wind loaded extraterrestrial dust that accumulated in deep-sea sediments and was subducted into the Earth’s mantle. To obtain additional constraints on this hypothesis, we analysed He, Ne and argon (Ar) in high pressure low temperature metamorphic rocks representing equivalents of former pelagic clays and cherts from Andros (Cyclades, Greece) and Laytonville (California, USA). While the metasediments contain significant amounts of 4He, 21Ne and 40Ar due to U, Th and K decay, no solar-type primordial noble gases were observed. Most of these were obviously lost during metamorphism preceding 30 km subduction depth. We also analysed magnetic fines from two Pacific ODP drillcore samples, which contain solar-type He and Ne dominated by solar energetic particles (SEP). The existing noble gas isotope data of deep-sea floor magnetic fines and interplanetary dust particles demonstrate that a considerable fraction of the extraterrestrial dust reaching the Earth has lost solar wind (SW) ions implanted at low energies, leading to a preferential occurrence of deeply implanted SEP He and Ne, fractionated He/Ne ratios and measurable traces of spallogenic isotopes. This effect is most probably caused by larger particles, as these suffer more severe atmospheric entry heating and surface ablation. Only sufficiently fine-grained dust may retain the original unfractionated solar composition that is characteristic for the Earth’s mantle He and Ne. Hence, in addition to the problem of metamorphic loss of solar noble gases during subduction, the isotopic and elemental fractionation during atmospheric entry heating is a further restriction for possible subduction hypotheses.

Schwarz, W. H.; Trieloff, M.; Altherr, R.

2005-08-01

45

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

46

A simple spectral solar irradiance model for cloudless maritime atmospheres  

Microsoft Academic Search

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

WATSON W. GREGG; K. L. CARDER

1990-01-01

47

Solar Ultraviolet Irradiance Variability During the Decline of Cycle 23  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

48

Modeled soft X-ray solar irradiances  

NASA Astrophysics Data System (ADS)

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 108 to a flux greater than 1 x 109 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

1994-06-01

49

Parameterization of Solar Global Uv Irradiation  

NASA Astrophysics Data System (ADS)

Daily doses of solar global UV-B, UV-A, and erythemal irradiation have been param- eterized to be calculated from pyranometer data of global and diffuse irradiation as well as from atmospheric column ozone measured at Potsdam (52 N, 107 m asl). The method has been validated against independent data of measured UV irradiation. A gain of information is provided by use of the parameterization for the three UV compo- nents (UV-B, UV-A and erythemal) referring to average values of UV irradiation. Ap- plying the method to UV irradiation measured at the mountain site Hohenpeissenberg (48 N, 977 m asl) shows that the parameterization even holds under completely differ- ent climatic conditions. On a long-term average (1953 - 2000), parameterized annual UV irradiation values are by 15 % (UV-A) and 21 % (UV-B), respectively, higher at Hohenpeissenberg, than they are at Potsdam. Using measured input data from 27 Ger- man weather stations, the method has been also applied to estimate the spatial distribu- tion of UV irradiation across Germany. Daily global and diffuse irradiation measured at Potsdam (1937 -2000) as well as atmospheric column ozone measured at Potsdam between1964 - 2000 have been used to derive long-term estimates of daily and annual totals of UV irradiation that include the effects of changes in cloudiness, in aerosols and, at least for the period 1964 to 2000, also in atmospheric ozone. It is shown that the extremely low ozone values observed mainly after the volcanic eruptions of Mt. Pinatubo in 1991 have substantially enhanced UV-B irradiation in the first half of the 90ies of the last century. The non-linear long-term changes between 1968 and 2000 amount to +4% ...+5% for annual global and UV-A irradiation mainly due to changing cloudiness, and +14% ... +15% for UV-B and erythemal irradiation due to both chang- ing cloudiness and decreasing column ozone. Estimates of long-term changes in UV irradiation derived from data measured at other German sites are addressed as well.

Feister, U.; Jaekel, E.; Gericke, K.

50

Lower Limit on Solar Irradiance Variation  

NASA Astrophysics Data System (ADS)

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

Goode, P. R.

2005-12-01

51

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

Microsoft Academic Search

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

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

1993-01-01

52

Extraterrestrial hydrogeology  

Microsoft Academic Search

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

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

2005-01-01

53

Some Characteristics of Global Solar Irradiation and Sunshine at Trieste.  

National Technical Information Service (NTIS)

Monthly data of global solar irradiation (GSI) and sunshine, GSI frequency tables per month and per year and monthly average hourly GSI are presented, in a form suitable for solar energy scientists, engineers and architects. Data refer to the meteorologic...

F. Stravisi P. C. Jain

1984-01-01

54

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

55

Solar irradiance variability during the October 2003 solar storm period  

NASA Astrophysics Data System (ADS)

The extraordinary solar storms between 18 October 2003 and 5 November 2003 include over 140 flares, primarily from two different large sunspot groups. There were 11 large X-class flares during this period, including an X17 flare on 28 October 2003 and an X28 flare on 4 November 2003. The X28 flare is the largest flare since GOES began its solar X-ray measurements in 1976. The solar (full-disk) irradiance during these flares was observed by the instruments aboard the NASA Solar Radiation and Climate Experiment (SORCE) spacecraft and the NASA Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) spacecraft. The total solar irradiance (TSI) dropped by unprecedented 0.34% during this period due to the dark, large sunspots. In addition, the TSI increased by 270 ppm during the X17 (4B optical) flare on 28 October, the first definitive measurement of a TSI flare event. The ultraviolet (UV) variations for this X17 flare range from a factor of about 50 shortward of 10 nm to about 10% for the Mg II 280 nm emission. One interesting result for the UV flare variations is that the broad wings of the H I Lyman-? (121.6 nm) emission increased by more than a factor of 2 during the X17 flare while the core of the Lyman-? emission only increased by 20%. Another interesting result is the time profile of the Si III 120.6 nm emission, which shows a sharp 1-minute long increase by a factor of 17 during the impulsive phase.

Woods, Thomas N.; Eparvier, Francis G.; Fontenla, Juan; Harder, Jerald; Kopp, Greg; McClintock, William E.; Rottman, Gary; Smiley, Byron; Snow, Martin

2004-05-01

56

Optimisation of buildings' solar irradiation availability  

SciTech Connect

In order to improve the sustainability of new and existing urban settlements it is desirable to maximise the utilisation of the solar energy incident on the building envelope, whether by passive or active means. To this end we have coupled a multi-objective optimisation algorithm with the backwards ray tracing program RADIANCE which itself uses a cumulative sky model for the computation of incident irradiation (W h/m{sup 2}) in a single simulation. The parameters to optimise are geometric (the height of buildings up to their facade and the height and orientation of roofs), but with the constraint of maintaining an overall built volume, and the objective function is heating season solar irradiation offset by envelope heat losses. This methodology has been applied to a range of urban typologies and produces readily interpretable results. The focus of this work is on the design of new urban forms but the method could equally be applied to examine the relative efficiency of existing urban settlements, by comparison of existing forms with the calculated optima derived from relevant specifications of the building envelope. (author)

Kaempf, Jerome Henri; Montavon, Marylene; Bunyesc, Josep; Robinson, Darren [Solar Energy and Building Physics Laboratory, Station 18, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Bolliger, Raffaele [Industrial Energy Systems Laboratory, Station 9, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)

2010-04-15

57

Reconstruction of solar spectral irradiance since the Maunder minimum  

NASA Astrophysics Data System (ADS)

Solar irradiance is the main external driver of the Earth's climate. Whereas the total solar irradiance is the main source of energy input into the climate system, solar UV irradiance exerts control over chemical and physical processes in the Earth's upper atmosphere. The time series of accurate irradiance measurements are, however, relatively short and limit the assessment of the solar contribution to the climate change. Here we reconstruct solar total and spectral irradiance in the range 115-160,000 nm since 1610. The evolution of the solar photospheric magnetic flux, which is a central input to the model, is appraised from the historical record of the sunspot number using a simple but consistent physical model. The model predicts an increase of 1.25 W/m2, or about 0.09%, in the 11-year averaged solar total irradiance since the Maunder minimum. Also, irradiance in individual spectral intervals has generally increased during the past four centuries, the magnitude of the trend being higher toward shorter wavelengths. In particular, the 11-year averaged Ly-? irradiance has increased by almost 50%. An exception is the spectral interval between about 1500 and 2500 nm, where irradiance has slightly decreased (by about 0.02%).

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

2010-12-01

58

Research Spotlight: More accurate measurements of total solar irradiance  

NASA Astrophysics Data System (ADS)

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

Tretkoff, Ernie

2011-02-01

59

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

60

Extraterrestrial Water  

Microsoft Academic Search

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

J. F. Kasting

2002-01-01

61

The measurement of solar irradiance on a tilted surface  

Microsoft Academic Search

The measurement of solar irradiance on a tilted plane has been compared using two methods. The irradiance was calculated from the measured total and diffuse irradiance in the horizontal plane assuming an isotropic sky and compared with that measured in the tilted plane. Differences were observed which depended on how the tilted solarimeter was mounted. It is concluded that provided

B. Justin; D. B. Pye; J. L. J. Rosenfeld

1979-01-01

62

Solar total irradiance in cycle 23  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

63

Anomalously low solar extreme-ultraviolet irradiance and thermospheric density during solar minimum  

Microsoft Academic Search

Solar activity during 2007–2009 was very low, and during this protracted solar minimum period, the terrestrial thermosphere was cooler and lower in density than expected. Measurements from instruments on the SOHO and TIMED spacecraft, and by suborbital rocket flights, indicate that solar extreme-ultraviolet irradiance levels were lower than they were during the previous solar minimum. Analysis of atmospheric drag on

Stanley C. Solomon; Thomas N. Woods; Leonid V. Didkovsky; John T. Emmert; Liying Qian

2010-01-01

64

A presentation of solar irradiation data suitable for solar energy application  

Microsoft Academic Search

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

R. L. Lougeay; A. J. Brazel

1984-01-01

65

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

66

Analysis of Different Solar Spectral Irradiance Reconstructions and Their Impact on Solar Heating Rates  

NASA Astrophysics Data System (ADS)

Proper numerical simulation of the Earth's climate change requires reliable knowledge of solar irradiance and its variability on different time scales, as well as the wavelength dependence of this variability. As new measurements of the solar spectral irradiance have become available, so too have new reconstructions of historical solar irradiance variations, based on different approaches. However, these various solar spectral irradiance reconstructions have not yet been compared in detail to quantify differences in their absolute values, variability, and implications for climate and atmospheric studies. In this paper we quantitatively compare five different reconstructions of solar spectral irradiance changes during the past four centuries, in order to document and analyze their differences. The impact on atmosphere and climate studies is discussed in terms of the calculation of short wave solar heating rates.

Thuillier, G.; Melo, S. M. L.; Lean, J.; Krivova, N. A.; Bolduc, C.; Fomichev, V. I.; Charbonneau, P.; Shapiro, A. I.; Schmutz, W.; Bolsée, D.

2013-09-01

67

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

Microsoft Academic Search

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in

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

1995-01-01

68

Long-term reconstructions of total solar irradiance  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

69

A reconstruction of solar irradiance using a flux transport model  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

70

The Search for Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

Looking at the nature, origin, and evolution of life on Earth is one way of assessing whether extraterrestrial life exists on Earth-like planets elsewhere (see Chaps. 5 and 6). A more direct approach is to search for favorable conditions and traces of life on other celestial bodies, both in the solar system and beyond. Clearly, there is little chance of encountering nonhuman intelligent beings in the solar system. But there could well be primitive life on Mars, particularly as in the early history of the solar system the conditions on Mars were quite similar to those on Earth. In addition, surprisingly favorable conditions for life once existed on the moons of Jupiter. Yet even if extraterrestrial life is not encountered in forthcoming space missions, it would be of utmost importance to recover fossils of past organisms as such traces would greatly contribute to our basic understanding of the formation of life. In addition to the planned missions to Mars and Europa, there are extensive efforts to search for life outside the solar system. Rapid advances in the detection of extrasolar planets, outlined in Chap. 3, are expected to lead to the discovery of Earth-like planets in the near future. But how can we detect life on these distant bodies?

Peter, Ulmschneider

71

Algorithms for estimating hourly solar irradiation on slopes  

Microsoft Academic Search

Solar radiation intensity on vertical walls and sloped surfaces is required in air conditioning plant design for buildings. This Note gives a comprehensive account of simple and 'user-friendly' algorithms for determining the sun's position, and then estimating hourly solar irradiation on a surface of given orientation and tilt.

T. Muneer

1989-01-01

72

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

73

Total solar irradiance observations from DIARAD/VIRGO  

NASA Astrophysics Data System (ADS)

The Differential Absolute Radiometer is making measurements of the total solar irradiance as part of the Variability of Irradiance and Gravity Oscillations experiment on the Solar and Heliospheric Observatory. We present the measurements made during its 7.8 years of operation, from 1996 until the present (2003). The aging due to UV exposure of the continuously measuring left channel is determined by comparison with the backup right channel; the loss in sensitivity of the left channel is 0.5 W/m2 or 364 ppm over 7.8 years. A raise of the total solar irradiance from a level of 1365.5 W/m2 at the end of the solar minimum in 1996 towards a maximum level of 1368 W/m2 at the beginning of 2002 has been measured by DIARAD.

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

2004-02-01

74

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

75

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

Microsoft Academic Search

Solar irradiance forecast is an important area of research for the future of the solar-based renewable energy systems. Numerical Weather Prediction models (NWPs) have proved to be a valuable tool for solar irradiance forecasting with lead time up to a few days. Nevertheless, these models show low skill in forecasting the solar irradiance under cloudy conditions. Additionally, climatic (averaged over

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

2010-01-01

76

Reconstructed and measured total solar irradiance: Is there a secular trend between 1978 and 2003?  

Microsoft Academic Search

Total solar irradiance reconstructed between 1978 and 2003 using solar surface magnetic field distributions is compared with three composites of total solar irradiance measurements. A good correspondence is found with the total solar irradiance composite from PMOD\\/WRC, with no bias between the three cycles. The agreement with the other composites (the ACRIM composite, mainly based on the Active Cavity Radiometer

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

2009-01-01

77

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

78

LISIRD: Where to go for Solar Irradiance Data  

NASA Astrophysics Data System (ADS)

LASP, the Laboratory for Atmospheric and Space Physics, has been providing web access to solar irradiance measurements, reference spectra, composites and model data covering the solar spectrum from .1 to 2400 nm through LISIRD, the LASP Interactive Solar IRradiance Datacenter. No single instrument can measure the solar spectral irradiance from X-rays to the IR, but the ensemble of LASP instruments can. LISIRD uses a single interface to provide easy, logical access to a variety of mission data, merged in time and wavelength. Daily space weather measurements are available, including total solar irradiance (TSI), Lyman Alpha (121 nm), Magnesium II Index (280 nm), He II (30.4 nm), FE XVI (33.5 nm), and the FUV continuum (145 to 165 nm). More recently, LISIRD has recently added the Whole Heliosphere Interval (WHI) Solar Irradiance time series, which provides a quiet sun reference spectra for the period of April 10-16 of 2008. LISIRD also recently added a composite solar spectral irradiance product over the range of 120 to 400 nm for the time period from November 8, 1978 to August 1, 2005. This product, created by Mathew Deland at SSAI, merges data from six different satellites into a single SSI product. And, we are currently adding a time series for daily solar spectral irradiance from 1950 to 2006, created by Judith Lean of the Naval Research Lab. This product adjusts observed irradiance for a given wavelength with parameters that represent known sources of variability at that wavelength. LISIRD remains committed to improving data access in a variety of ways. We are planning and developing a means for the broader community of scientists to easily determine data availability for a particular date range without having to know mission or instrument details. Improved data subsetting will allow users to request only the time range or spectra that users need, making data management generally easier. We expect to continue to enhance our data offerings. Future vision for LISIRD also includes integration of improved data visualization and analysis tools. We welcome contributions from solar science community members who wish to share data and tools they have developed. We also expect to integrate LISIRD with the Virtual Solar Observatory (VSO) and other relevant Virtual Observatories (VOs) for a more integrated and complete user experience. We are actively seeking input and feedback to improve LISIRD from interested users of this data. Towards this end we have provided a survey at our website and to AGU attendees. Those who use LISIRD and provide feedback will have the opportunity to help steer LISIRD development. Let us know what you would like to see and we will try to make it happen!

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

2008-12-01

79

1/f noise in the UV solar spectral irradiance  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

80

Tsiolkovsky and extraterrestrial intelligence  

NASA Astrophysics Data System (ADS)

Where is everybody? Fermi's famous question about the apparent absence of evidence of extraterrestrials and the answers to it offered by Ball, Kuiper and Morris during the search for extraterrestrial intelligence (SETI) debates of the 1970s were anticipated in the writings of the pioneering Russian space theorist Konstantin Tsiolkovsky. Although Tsiolkovsky is most widely known for his work on spaceflight theory and his visions of humans living in space, he was also a dedicated monist who believed life existed throughout the cosmos and that we were surrounded by extraterrestrial species far more intelligent than us. To explain why advanced extraterrestrials had not made their presence known to us, or, more importantly, had not interfered with our evolution to raise us to their own level, Tsiolkovsky proposed that they were deliberately leaving us alone in the hope that we might develop "a new and wonderful stream of life that will renew and supplement their already perfected life".

Finney, B.; Lytkin, V.; Finney, L.

2000-06-01

81

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

82

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

83

The extraterrestrial Casimir Effect  

NASA Astrophysics Data System (ADS)

Application of the Electro-Gravi-Magnetic (EGM) Photon radiation method to the Casimir Effect (CE), suggests that the experimentally verified (terrestrially) neutrally charged Parallel-Plate configuration force, may differ within extraterrestrial gravitational environments from the gravitationally independent formulation by Casimir. Consequently, the derivation presented herein implies that a gravitationally dependent CE may become an important design factor in nanotechnology for extraterrestrial applications (ignoring finite conductivity + temperature effects and evading the requirement for Casimir Force corrections due to surface roughness).

Storti, Riccardo C.

2011-09-01

84

Solar extreme ultraviolet irradiance: Present, past, and future  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

85

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

Microsoft Academic Search

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

John H. Jerome; Robert P. Bukata

1998-01-01

86

Proton irradiated heteroepitaxial InP solar cells  

Microsoft Academic Search

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

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

1993-01-01

87

Measuring and modeling solar irradiance on vertical surfaces  

NASA Astrophysics Data System (ADS)

Presented are the first evaluations of 5 algorithms for converting global horizontal and direct normal solar irradiance components to global irradiance on tilted surfaces using measurements from the Solar Radiation Research Laboratory (SRRL) at SERI. High resolution (15-min) measurements from 8 thermopile radiometers oriented vertically in the 4 cardinal directions were available for a 169-day period ending 31 December 1984. Concurrent measurements of global horizontal and direct normal solar irradiance components were also used. The pyranometers used were intercompared on horizontal, north-facing, and south-facing vertical orientations. The conversion algorithms each attempt to account for the very complex atmospheric interactions with incoming solar radiation. The sky and ground radiance contributions to tilted surface are assumed to be isotropic, anisotropic, or a combination of the two depending on the algorithm. Results from the analysis of measurements on vertical surfaces for 22 July through 4 September indicate a general overestimate (18% to 46.5%) of solar irradiance on north-facing surfaces by all 5 of the algorithms. The best agreement with measured data was demonstrated for south-facing surfaces where all but one algorithm were within the present measurement by as much as 23% of the observed 15-min data.

Maxwell, E. L.; Stoffel, T. L.; Bird, R. E.

1986-07-01

88

Genesis capturing the sun: Solar wind irradiation at Lagrange 1  

NASA Astrophysics Data System (ADS)

Genesis, a member of NASAs Discovery Mission program, is the world’s first sample return mission since the Apollo program to bring home solar matter in ultra-pure materials. Outside the protection of Earth’s magnetosphere at the Earth-Sun Lagrange 1 point, the deployed sample collectors were directly exposed to solar wind irradiation. The natural process of solar wind ion implantation into a highly pure silicon (Si) bulk composition array collector has been measured by spectroscopic ellipsometry and scanning transmission electron microscopy (STEM). Ellipsometry results show that bulk solar wind ions composed of approximately 95% H+, 4% He+ and <1% other elements physically altered the first 59-63 nm of crystalline silicon substrate during 852.8 days of solar exposure. STEM analysis confirms that the solar accelerated ions caused significant strain and visible structural defects to the silicon structure forming a 60-75 nm thick irradiation damage region directly below the surface SiO2 native oxide layer. Monte Carlo simulations of solar wind H, He, C, O, Ne, Mg, Si and Fe ion collisions in the Si collector with fluences calculated from the Genesis and ACE spacecrafts were used to estimate the energy deposited and Si vacancies produced by nuclear stopping in a flight-like Si bulk array collector. The coupled deposited energy model with the flown Genesis Si in situ measurements provides new insight into the basic principles of solar wind diffusion and space weathering of materials outside Earth’s magnetosphere.

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

2009-04-01

89

Analysis of Solar Irradiation Anomalies in Long Term Over India  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

90

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

PubMed

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

Sola, Yolanda; Lorente, Jerónimo; Ossó, Albert

2012-09-21

91

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

92

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

NASA Astrophysics Data System (ADS)

The variability in solar irradiance, the main external energy source of the Earth's system, must be critically studied in order to place the effects of human-driven climate change into perspective and allow plausible predictions of the evolution of climate. Accurate measurements of total solar irradiance (TSI) variability by instruments onboard space platforms during the last three solar cycles indicate changes of approximately 0.1% over the sunspot cycle. Physics-based models also suggest variations of the same magnitude on centennial to millennia time-scales. Additionally, long-term changes in Earth's orbit modulate the solar irradiance reaching the top of the atmosphere. Variations of orbital inclination in relation to the Sun's equator could potentially impact incoming solar irradiance as a result of the anisotropy of the distribution of active regions. Due to a lack of quantitative estimates, this effect has never been assessed. Here, we show that although observers with different orbital inclinations experience various levels of irradiance, modulations in TSI are not sufficient to drive observed 100 kyr climate variations. Based on our model we find that, due to orbital inclination alone, the maximum change in the average TSI over timescales of kyrs is ˜0.003 Wm-2, much smaller than the ˜1.5 Wm-2 annually integrated change related to orbital eccentricity variations, or the 1-8 Wm-2 variability due to solar magnetic activity. Here, we stress that out-of-ecliptic measurements are needed in order to constrain models for the long-term evolution of TSI and its impact on climate.

Vieira, L. E. A.; Norton, A.; Dudok de Wit, T.; Kretzschmar, M.; Schmidt, G. A.; Cheung, M. C. M.

2012-08-01

93

Space settlements and extraterrestrial resources: what benefits to SPS construction  

SciTech Connect

Two views widely held by space resources advocates are challenged, and an evolutionary approach is suggested rather than all-up or bootstrap approaches to space resources utilization. The first challenge is that potential cost savings accruable through use of large habitats that allow extended space crew tours of duty may be the economic lever that allows utilization of extraterrestrial resources. The conventional view challenged is that extraterrestrial resources will provide the economic lever that allows the large habitats. The second challenge asserts that the available estimates of labor required to manufacture solar power satellites from extraterrestrial materials are low by a wide margin, and that the economic advantages claimed for extraterrestrial resources for solar power satellite manufacture may not exist. Cost estimation techniques and their application to this question are emphasized. (LEW)

Woodcock, G.R.

1982-01-01

94

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

95

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

96

Variation of the Nimbus 7 Total Solar Irradiance.  

National Technical Information Service (NTIS)

For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.65 Wm(exp -2), a coefficient o...

R. M. Wilson

1992-01-01

97

Daily, Monthly and Annual Variations in Solar Ultraviolet Irradiance.  

National Technical Information Service (NTIS)

Solar ultraviolet-B (290-320 nm: UV-B), ultraviolet A (320-400 nm: UV-A) and Total (300-3000 nm) irradiances on the ground had been measured at Shonan Campus of Tokai University, Hiratsuka (35 deg N) for two years from October 1990 to September 1992, usin...

S. Takeshita N. Sudo T. Sakata M. Sasaki

1993-01-01

98

Systematic error in the measurement of very high solar irradiance  

Microsoft Academic Search

The measurement of very high solar irradiance is required in an increasingly wide variety of technical applications. There is really only one commercial supplier of heat flux sensors that can be used for this purpose. These gages are calibrated using a black body as the radiant source. A systematic error has been detected when these heat flux sensors are later

J Ballestr??n; S Ulmer; A Morales; A Barnes; L. W Langley; M Rodr??guez

2003-01-01

99

Surface solar irradiance from SCIAMACHY measurements: algorithm and validation  

Microsoft Academic Search

Broadband surface solar irradiances (SSI) are, for the first time, derived from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) satellite measurements. The retrieval algorithm, called FRESCO (Fast REtrieval Scheme for Clouds from the Oxygen A band) SSI, is similar to the Heliosat method. In contrast to the standard Heliosat method, the cloud index is replaced by the effective cloud

P. Wang; P. Stammes; R. Mueller

2011-01-01

100

Surface solar irradiance from SCIAMACHY measurements: algorithm and validation  

Microsoft Academic Search

Broadband surface solar irradiances (SSI) are, for the first time, derived from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) satellite measurements. The retrieval algorithm, called FRESCO (Fast REtrieval Scheme for Clouds from Oxygen A band) SSI, is similar to the Heliosat method. In contrast to the standard Heliosat method, the cloud index is replaced by the effective cloud fraction

P. Wang; P. Stammes; R. Mueller

2011-01-01

101

Fuzzy modeling of solar irradiance on inclined surfaces  

Microsoft Academic Search

A model of solar irradiance on arbitrarily oriented inclined surfaces is proposed, based on fuzzy logic procedures. The behavior of the proposed model is similar to that of other models of increased performance such as the models of Perez or Gueymard, though it requires only a very limited number of classes and adjustable parameters. The use of fuzzy clustering optimizes

V. Gómez; A. Casanovas

2003-01-01

102

Spectral Irradiance Curve Calculations for Any Type of Solar Eclipse.  

National Technical Information Service (NTIS)

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

A. Deepak J. E. Merrill

1974-01-01

103

Solar irradiance variability during the October 2003 solar storm period  

Microsoft Academic Search

The extraordinary solar storms between 18 October 2003 and 5 November 2003 include over 140 flares, primarily from two different large sunspot groups. There were 11 large X-class flares during this period, including an X17 flare on 28 October 2003 and an X28 flare on 4 November 2003. The X28 flare is the largest flare since GOES began its solar

Thomas N. Woods; Francis G. Eparvier; Juan Fontenla; Jerald Harder; Greg Kopp; William E. McClintock; Gary Rottman; Byron Smiley; Martin Snow

2004-01-01

104

Solar total irradiance and sunspot area in 1981  

NASA Astrophysics Data System (ADS)

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.

105

Solar UV irradiation and dermal photoaging  

Microsoft Academic Search

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

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

2001-01-01

106

Solar irradiance, cosmic rays and cloudiness over daily timescales  

NASA Astrophysics Data System (ADS)

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

Laken, Benjamin A.; ?alogovi?, Jasa

2011-12-01

107

Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow  

NASA Astrophysics Data System (ADS)

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.

1993-08-01

108

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

109

Solar spectral irradiance variability in the ultraviolet from SORCE and UARS SOLSTICE  

NASA Astrophysics Data System (ADS)

The SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) on the SOlar Radiation and Climate Experiment (SORCE) has been measuring the solar spectral irradiance on a daily basis since early 2003. This time period includes near-solar maximum conditions, the Halloween storms of 2003, and solar minimum conditions. These results can be compared to observations from the SOLSTICE I experiment that flew on the Upper Atmosphere Research Satellite (UARS) during the decline of the previous solar cycle as well as with currently operating missions. We will discuss similarities and differences between the two solar cycles in the long-term ultraviolet irradiance record.

Snow, M.; McClintock, W. E.; Woods, T. N.

2010-08-01

110

Estimation of solar irradiance on tilted surfaces facing south for Tanta, Egypt  

Microsoft Academic Search

This paper aims to investigate a computer program using Pascal language to estimate solar irradiance on inclined surfaces. The global solar irradiance on horizontal surfaces is measured for Tanta at 30°47? latitude and 30°99? longitude for the period 2008–2009. The computer program has been prepared to calculate the monthly average daily irradiance and hourly solar irradiance on inclined surfaces using

A. Ibrahim; A. A. El-Sebaii; M. R. I. Ramadan; S. M. El-Broullesy

2011-01-01

111

Extraterrestrial Materials Processing.  

National Technical Information Service (NTIS)

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 o...

W. H. Steurer

1982-01-01

112

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

113

Irradiance optimization of outdoor microalgal cultures using solar tracked photobioreactors.  

PubMed

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

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

2012-07-31

114

Accuracies of Incoming Radiation: Calibrations of Total Solar Irradiance Instruments  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

115

An Improved Total Solar Irradiance Climate Data Record  

NASA Astrophysics Data System (ADS)

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

Kopp, G.

2011-12-01

116

Photometric measurements of solar irradiance variations due to sunspots  

SciTech Connect

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

Chapman, G.A.; Herzog, A.D.; Laico, D.E.; Lawrence, J.K.; Templer, M.S. (San Fernando Observatory, El Segundo, CA (USA))

1989-08-01

117

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

Microsoft Academic Search

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

P. C. Simon

1983-01-01

118

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

119

Mechanisms for total and spectral solar irradiance variations  

NASA Astrophysics Data System (ADS)

The total and spectral irradiance varies over short time scales, i.e. from days to months, and longer time scales from years to decades, centuries, and beyond. In this talk we review the current understanding of irradiance changes from days to decades. We present the current status of observations and discuss proposed reconstruction approaches to understand these variations. The main question that ultimately needs to be answered is what are the physical processes that could explain the enhanced heating of the photosphere, chromosphere, transition region, and corona, leading to a change in the solar radiative output at various wavelengths. As semi-empirical models allow us to reproduce the solar spectrum over a broad wavelength range, they offer a powerful tool to determine the energy necessary to heat certain layers and at the same time balance the radiative losses.

Haberreiter, Margit

2010-02-01

120

Assessment of the Solar Irradiance Record for Climate Studies  

NASA Astrophysics Data System (ADS)

The total solar irradiance has been measured from space for an uninterrupted 34 years, providing a record of the total radiative energy driving the Earth's climate system. This climate driver, which is 2500 times greater than all other energy sources combined, is observed to vary on scales of minutes and years and likely varies over much longer time periods; although definitive knowledge of such long-term variations, while critical for climate studies, is currently limited by instrument accuracy and stability. I assess the current knowledge of the spaceborne measurement record's accuracy, stability, and requirements, and present recent and upcoming improvements to the existing record resulting from current international calibration and collaboration efforts. I also discuss the status of the instruments currently providing irradiance measurements and future plans to maintain this solar climate data record.

Kopp, Greg

2013-04-01

121

An Analysis of Solar Radiation Data for Fort Collins, Colorado.  

National Technical Information Service (NTIS)

Work with solar radiation reaching the earth's surface frequently requires a knowledge of the extraterrestrial solar radiation. A method of calculating extraterrestrial solar radiation over various time scales (i.e. instantaneous, hourly, daily, etc.) wit...

J. R. Conley

1982-01-01

122

Solar Bolometric Imager for Investigating the Sources of Solar Irradiance Variability  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

123

Selection of input parameters to model direct solar irradiance by using artificial neural networks  

Microsoft Academic Search

A very important factor in the assessment of solar energy resources is the availability of direct irradiance data of high quality. However, this component of solar radiation is seldom measured and thus must be estimated from data of global solar irradiance, which is registered in most radiometric stations. In recent years, artificial neural networks (ANN) have shown to be a

G. López; F. J. Batlles; J. Tovar-Pescador

2005-01-01

124

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

Microsoft Academic Search

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

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

2006-01-01

125

Extraterrestrial Intelligent Life  

NASA Astrophysics Data System (ADS)

Having laid some extensive groundwork, we are finally ready to address the central questions of the existence and possible nature of extraterrestrial intelligent life. Although no trace of such life has so far been found, there are clearly compelling reasons for its existence. In Chap. 4 we estimated that Earth-like planets should occur quite frequently in our galaxy, and in Chaps. 5 and 6 it was shown how life, and intelligent life, have formed on Earth. Using the Drake formula, these results will now be combined to estimate the expected number of extraterrestrial intelligent societies. Since many probability factors entering this equation are controversial, the opinions of various authors will be discussed.

Peter, Ulmschneider

126

[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

127

Total solar irradiance record accuracy and recent improvements  

NASA Astrophysics Data System (ADS)

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

Kopp, Greg

128

Total Solar Irradiance Variability from 1978 to present  

NASA Astrophysics Data System (ADS)

Since February 1996 VIRGO radiometers observe total solar irradiance from SOHO at L1, allowing continuous and uninterrupted observations of the Sun. Besides the 3-month gap during the SOHO vacation in summer 1998 and a few other minor gaps the record covers more than 99% of the almost 8 years of operation. This allows a very detailed assessment of the long-term behaviour of the two VIRGO radiometers, PMO6V and DIARAD. The results of this analysis are presented and their implications for other space radiometers discussed. With these data and those from HF/NIMBUS7, ACRIM-I/SMM and ACRIM-II/UARS a composite of total solar irradiance (TSI) is presented (updated and improved from Fröhlich and Lean, 1998), which covers now almost three solar cycles starting in November 1978, just before the maximum of solar cycle 21. Radiometrically the composite is based on ACRIM-I and ACRIM-II, with the latter shifted to the scale of ACRIM-I. During the gap between ACRIM-I and II the results from the HF radiometer are used. These data need to be corrected for a change which was first detected by comparison with ERBS. The inclusion or omittance of this change is the main reason for the discrepancy between this composite and the one presented by Willson and Mordvinov (2003). The discussion concentrates on this change and its determination by comparison of HF with ERBS and a proxy model for interpolation between its 14-day observations. Comparison of the composite with ERBS over the period from 1984-2003 supports very strongly the validity and need of the HF correction and confirms that TSI had no significant trend over the last 25 years of observation from space. References: C. Fröhlich and J. Lean, 1998, The Sun's Total Irradiance: Cycles and Trends in the Past Two Decades and Associated Climate Change Uncertainties, Geophys. Res. Let., 25, 4377--4380 R. C. Willson and A.~V. Mordvinov, 2003, Secular Total Solar Irradiance trend during solar cycles 21-23, Geophys. Res. Let., 30, 1199--1202

Fröhlich, C.

2003-12-01

129

Measurements of Solar UV Irradiance during Solar Cycles 22 and 23  

NASA Astrophysics Data System (ADS)

During the past two solar cycles, absolutely calibrated measurements of the solar UV spectral irradiance (120-400 nm) have been gathered by several instruments on a daily cadence over durations extending for several years. Accurate and ongoing calibration is of primary impor-tance for these solar UV measurements because of changes in their responsivities experienced by these instruments. The SBUV2 instrument aboard the NOAA-11 spacecraft was calibrated via measurements of a similar instrument (SSBUV) aboard 7 flights of the space shuttle and conducted measurements during the SC 22 maximum and most of its decline (1988-1994). The SUSIM and SOLSTICE instruments aboard UARS measurements during the decline of SC 22 and through the SC 23 maximum (1991-2005); their calibration was provided by redundant channels/lamps and by stellar observations, respectively. The TIMED/SEE performed mea-surements during the decline of SC 23 (2002-present); its calibration was provided by onboard redundant channels and measurements by a similar instrument aboard rockets. Variations in these solar UV irradiance time series generally agree with one another despite occasional trends introduced by responsivity that are unaccounted for. Significant variations are present that correspond to solar cycle and rotation periodicities. The amplitudes of the solar cycle variations range from in excess of 50line to less than 1in irradiance variation with respect to wavelength, the variations are nevertheless linearly related to one another and to the MgII core-to-wing ratio index. Comparisons with the MgII index are used as a tool to better understand the measured variations among the experiments and between the solar cycles 22 and 23. Correspondence with MgII is especially useful above above 300 nm where the solar variations are comparable or less than instrumental trends.

Floyd, Linton

130

Microorganisms and extraterrestrial travel  

Microsoft Academic Search

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

Alfred W. Crosby

131

Variability of the solar spectral irradiance and energetic particles  

NASA Astrophysics Data System (ADS)

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

Silva-Válio, Adriana

2010-02-01

132

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

NASA Astrophysics Data System (ADS)

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

Frohlich, C.

2010-12-01

133

Atmospheric water vapour of extraterrestrial origin - A discussion of its possible role in sun-weather relationships  

Microsoft Academic Search

It is shown that at the present time the influx (or accretion) of extraterrestrial hydrogen to the earth atmosphere makes an insignificant contribution to the concentration of water vapor in the atmosphere. The sources of extraterrestrial hydrogen that are investigated quantitatively are: (1) solar flare protons, (2) galactic cosmic ray protons, (3) solar wind (including auroral) protons, and (4) neutral

D. M. Willis

1978-01-01

134

Modelling solar irradiance from HRV images of Meteosat Second Generation  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

135

Reconstruction of total solar irradiance 1974-2009  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

136

Surface Solar Irradiance in the Central Pacific during Tropic Heat: Comparisons between in Situ Measurements and Satellite Estimates  

Microsoft Academic Search

We present the first results concerning solar radiation at the ocean surface during the Tropic Heat experiment. Using calibrated GOES visible brightness measurements, a simple radiative transfer model calculates hourly and daily surface solar irradiance values. To validate the satellite-estimated solar irradiance, surface solar irradiance measurements are taken from three sources; the Tropic Heat buoy 3, the R\\/V Weeama, and

Catherine Gautier

1988-01-01

137

A "Toy" Simulation of Total Solar Irradiance Variations  

NASA Astrophysics Data System (ADS)

Recently, we have developed a method for deducing the total solar irradiance S from sunspot area AS using a finite impulse response FIR which, when convolved with AS, produces S (Preminger & Walton 2005, JGR, submitted). In an effort to gain physical insight into the meaning of the FIR, we have produced a simple model of the solar cycle with the following characteristics: (1) nd sunspots per day are generated, each with a fixed area AS = 500 millionths of the solar hemisphere; (2) sunspots decay exponentially with time constant ?S = 10 days; (3) decayed sunspot area becomes faculae, which in turn decay with a time constant ?F = 45 days. These parameters were deduced from various characteristics of the actual solar cycle. Each sunspot is generated at a random solar longitude, and the faculae remain at the same longitude as the sunspots. Latitude variation is not modeled; that is, they are always zero. We allow nd to vary as a simple cosine bell from 0 up to nd,max. Simple models of sunspot and facular contrast are used to compute a pseudo-TSI. When nd,max=1, the resulting model reproduces a few of the observed characteristics of the solar activity cycle; e.g., the projected sunspot and facular area peak at about 1500 and 45,000 parts per million of the solar disk. If we use this simple model to compute a FIR, it has a very similar shape to the one found empirically from the actual measured S and AS. The model FIR is also independent of nd,max over the range 0.1 to 10. It is missing some qualitatively important characteristics, however, in particular the fact that S actually begins to rise some time before AS; we are investigating refinements to our model which might reproduce this property of the empirical FIR.

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

2005-05-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

139

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

140

Possible extraterrestrial strategy for earth  

Microsoft Academic Search

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

J. W. Deardorff

1986-01-01

141

The analysis of extraterrestrial materials  

Microsoft Academic Search

The impact of the planetary exploration program and the study of extraterrestrial materials are examined. Terrestrial laboratories and techniques (chemical and rare gas analyses, age determinations, gamma-ray measurements, electron-probe studies, and the ion microprobe) for analyzing meteorites and lunar samples, and cosmochronology methods are described. The remote analysis of extraterrestrial materials, remote sensing by reflectance spectroscopy, surface analysis from orbiting

I. Adler

1986-01-01

142

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

143

Solar Surface Magnetism and Irradiance on Time Scales from Days to the 11-Year Cycle  

NASA Astrophysics Data System (ADS)

The uninterrupted measurement of the total solar irradiance during the last three solar cycles and an increasing amount of solar spectral irradiance measurements as well as solar imaging observations (magnetograms and photometric data) have stimulated the development of models attributing irradiance variations to solar surface magnetism. Here we review the current status of solar irradiance measurements and modelling efforts based on solar photospheric magnetic fields. Thereby we restrict ourselves to the study of solar variations from days to the solar cycle. Phenomenological models of the solar atmosphere in combination with imaging observations of solar electromagnetic radiation and measurements of the photospheric magnetic field have reached high enough quality to show that a large fraction (at least, about 80%) of the solar irradiance variability can be explained by the radiative effects of the magnetic activity present in the photosphere. Also, significant progress has been made with magnetohydrodynamic simulations of convection that allow us to relate the radiance of the photospheric magnetic structures to the observations.

Domingo, V.; Ermolli, I.; Fox, P.; Fröhlich, C.; Haberreiter, M.; Krivova, N.; Kopp, G.; Schmutz, W.; Solanki, S. K.; Spruit, H. C.; Unruh, Y.; Vögler, A.

2009-07-01

144

The Sensitivity Of d2h Of Antarctic Peninsula Ice To Changes In Total Solar Irradiance  

Microsoft Academic Search

The effective solar irradiance is a net result of processes in the solar photosphere due to, mainly, the sunspots and the magnetic bright faculae. Since by the end of the 70's decade, instruments on board of satellites were able to measure this parameter. Although, two independent data set from the Active Cavity Radiometer Irradiance Monitor (ACRIM I) and the Earth

H. Evangelista; N. R. Rigozo; J. Cardia Simoes

2004-01-01

145

Calibration of the solar EUV spectral irradiance instruments aboard the TIMED and SDO satellites  

Microsoft Academic Search

Understanding both the absolute value and time variability of the solar extreme ultraviolet (EUV) spectral irradiance is necessary for understanding the structure and variability of the Earth's thermosphere and ionosphere. Long-term measurement of the solar EUV irradiance requires a calibration scheme that addresses the following issues: (1) The calibration must be referenced to repeatable radiometric standards; (2) Changes in calibration

F. G. Eparvier; T. N. Woods

2004-01-01

146

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

NASA Astrophysics Data System (ADS)

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

Sofia, Sabatino

2004-06-01

147

An evaluation of the correlation between open solar flux and total solar irradiance  

NASA Astrophysics Data System (ADS)

The correlation between the coronal source flux FS and the total solar irradiance ITS is re-evaluated in the light of an additional 5 years' data from the rising phase of solar cycle 23 and also by using cosmic ray fluxes detected at Earth. Tests on monthly averages show that the correlation with FS deduced from the interplanetary magnetic field (correlation coefficient, r = 0.62) is highly significant (99.999%), but that there is insufficient data for the higher correlation with annual means (r = 0.80) to be considered significant. Anti-correlations between ITS and cosmic ray fluxes are found in monthly data for all stations and geomagnetic rigidity cut-offs (r ranging from -0.63 to -0.74) and these have significance levels between 85% and 98%. In all cases, the fit is poorest for the earliest data (i.e., prior to 1982). Excluding these data improves the anticorrelation with cosmic rays to r = -0.93 for one-year running means. Both the interplanetary magnetic field data and the cosmic ray fluxes indicate that the total solar irradiance lags behind the open solar flux with a delay that is estimated to have an optimum value of 2.8 months (and is within the uncertainty range 0.8-8.0 months at the 90% level).

Lockwood, M.

2002-02-01

148

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.

149

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

NASA Astrophysics Data System (ADS)

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

Ortegón Gallego, A.

2010-09-01

150

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

NASA Astrophysics Data System (ADS)

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

Kretzschmar, Matthieu; Dominique, Marie; Dammasch, Ingolf

2013-04-01

151

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

NASA Astrophysics Data System (ADS)

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

Huang, Yanshi

2012-10-01

152

Solar total irradiance variations and the global sea surface temperature record  

Microsoft Academic Search

The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the 11-year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the solar ``constant'') that is in phase with the solar-cycle envelope, supporting and updating

George C. Reid

1991-01-01

153

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

Microsoft Academic Search

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

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

1992-01-01

154

Extraterrestrials - Where are they?  

NASA Astrophysics Data System (ADS)

Explanations for the absence of evidence for extraterrestrial beings are discussed, together with the probabilities of other habitable planets in the universe, programs to detect radio signals from other civilizations, and the processes that can lead to the appearance of life. Probability estimates are presented for the appearance of life, the occurrence of interstellar colonization, and the times involved in interstellar colonization. It is suggested that the first civilization to begin interstellar colonization will be the civilization that colonizes the Galaxy, and calculations are presented for the propulsion methods, techniques for terraforming planets, and the incidence of habitable planets in the Galaxy. Primordial organic chemistry is reviewed, together with nucleosynthesis and evolution in the Galaxy, and consideration is devoted to the rate of formation of DNA strands and other substances by which life forms could exist in the infinite universe. For individual items see A83-41502 to A83-41515

Hart, M. H.; Zuckerman, B.

155

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

156

[Extraterrestrial influences on health and disease].  

PubMed

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

Sitar, J

1994-02-14

157

A Cryogenic Pyrheliometer for More Accurate Solar Irradiance Measurements  

NASA Astrophysics Data System (ADS)

Space-borne pyrheliometry over the past two solar cycles has demonstrated the variability of total solar irradiance in response to photospheric magnetic structures such as sunspots or faculae, over the 11-yr activity cycle.But the reproducibility of the measurements remains marginal to detect or rule out possible trends in irradiance below the 0.05-0.1% variation over the 11-yr cycle, but conceivably dominant over multi-decadal time scales of greatest relevance to climate. In metrology laboratories,conventional radiometers similar to those presently flown by NASA and ESA have been superseded in the past ten years by cryogenic radiometers of ten times higher absolute accuracy and long term reproducibility.But their helium cooling makes them difficult to use in space. Recently, advances in superconducting transition thermometry at NIST, and in high-temperature superconducting materials,have presented the opportunity to reach cryogenic radiometer performance at LN2 temperatures attainable with space qualified single stage cryocoolers. We report here on our results with a prototype SCT-based radiometer, developed to investigate this opportunity to improve the accuracy of space borne pyrheliometry.We show that the sensitivity achieved is an order of magnitude better than with conventional radiometers, although the noise threshold falls short of values attainable with LHe cooling.The measured non-equivalence errors, and results of monochromatic intercomparisons against trap detectors, are both consistent with absolute accuracy at the 0.01% level, thus comparable to LHe cooled radiometers. Improved thermal and mechanical design will be required to reduce slow drifts, to test this accuracy conclusively.

Foukal, P.

2003-05-01

158

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

NASA Astrophysics Data System (ADS)

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.

1983-03-01

159

Total Solar Irradiance: Present status of TSI observations  

NASA Astrophysics Data System (ADS)

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

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

160

Apparent absorption of solar spectral irradiance in heterogeneous ice clouds  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

161

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

NASA Astrophysics Data System (ADS)

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

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

162

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

NASA Astrophysics Data System (ADS)

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

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

163

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

PubMed

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

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

2004-07-20

164

Finding Extraterrestrial Organisms Living on Thermosynthesis  

NASA Astrophysics Data System (ADS)

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

Muller, Anthonie W. J.

2003-11-01

165

Finding extraterrestrial organisms living on thermosynthesis.  

PubMed

During thermal cycling, organisms could live on thermosynthesis, a theoretical mechanism applicable to the origin of life and the early evolution of biological energy conversion. All extraterrestrial ice may be a repository for frozen dead or dormant organisms from earlier stages of evolution. In the presence of a thermal gradient within the ice, organisms might still be harvesting energy from thermosynthesis. Possible habitats for thermosynthesizers can be found throughout the Solar System, particularly in the cold traps on Mercury and the Moon, convecting waters on Mars, the oceans on moons in the outer Solar System, and smaller bodies rotating in the sunlight such as cosmic dust, meteorites, asteroids, and comets. A general strategy for detecting thermosynthetic organisms on Earth is offered, and highlights of current and upcoming robotic exploratory missions relevant to the detection of thermosynthesis are reviewed. PMID:14678664

Muller, Anthonie W J

2003-01-01

166

Changes in surface solar UV irradiances and total ozone during the solar eclipse of August 11, 1999  

NASA Astrophysics Data System (ADS)

During the solar eclipse of August 11, 1999, intensive measurements of UV solar irradiance and total ozone were performed at a number of observatories located near the path of the Moon's shadow. At the Laboratory of Atmospheric Physics (LAP) of the Aristotle University of Thessaloniki, Greece, global and direct spectra of UV solar irradiances (285-365 nm) were recorded with a double monochromator, and erythemal irradiances were measured with broadband pyranometers. In addition, higher-frequency measurements of global and direct irradiances at six UV wavelengths were performed with a single Brewer spectrophotometer. Total ozone measurements were also performed with Dobson and Brewer spectrophotometers at Hradec Kralove (Czech Republic), Ispra (Italy), Sestola (Italy), Hohenpeissenberg (Germany), Bucharest (Romania), Arosa (Switzerland), and Thessaloniki (Greece). From the spectral UV measurements the limb darkening effect of the solar disk was tentatively quantified from differences of measured solar spectral irradiances at the peak of the eclipse (near to limb conditions) and before the eclipse. Two blackbody curves were fit to the preeclipse and peak eclipse spectra, which have shown a difference in effective temperatures of about 165°K between the limb and the whole of the solar disk. The limb darkening effect is larger at the shorter UV wavelengths. The ratio of the diffuse to direct solar irradiances during the eclipse shows that the diffuse component is reduced much less compared to the decline of the direct solar irradiance at the shorter wavelengths. Moreover, a 20-min oscillation of erythemal UV-B solar irradiance was observed before and after the time of the eclipse maximum under clear skies, indicating a possible 20-min fluctuation in total ozone, presumably caused by the eclipse-induced gravity waves. This work also shows that routine total ozone measurements with a Brewer or a Dobson spectrophotometer should be used with caution during a solar eclipse. This is because the diffuse light increases by more than 30% with respect to the direct solar radiation, increasing more at the shorter wavelength side of the UV spectrum. This plausible mechanism introduces an artificial decrease in total ozone during solar eclipse of more than 30 Dobson units (DU), which is confirmed by all Brewer and Dobson measurements. Changes in total ozone cited earlier in the refereed literature have not been confirmed in the present study.

Zerefos, C. S.; Balis, D. S.; Meleti, C.; Bais, A. F.; Tourpali, K.; Kourtidis, K.; Vanicek, K.; Cappellani, F.; Kaminski, U.; Colombo, T.; Stübi, R.; Manea, L.; Formenti, P.; Andreae, M. O.

2000-11-01

167

A method for filling gaps in solar irradiance and solar proxy data  

NASA Astrophysics Data System (ADS)

Context. Data gaps are ubiquitous in spectral irradiance data, and yet, little effort has been put into finding robust methods for filling them. Aims: We introduce a data-adaptive and nonparametric method that allows us to fill data gaps in multi-wavelength or in multichannel records. Methods: This method, which is based on the iterative singular value decomposition, uses the coherency between simultaneous measurements at different wavelengths (or between different proxies) to fill the missing data in a self-consistent way. The interpolation is improved by handling different time scales separately. Results: Two major assets of this method are its simplicity, with few tuneable parameters, and its robustness. Two examples of missing data are given: one from solar EUV observations, and one from solar proxy data. The method is also appropriate for building a composite out of partly overlapping records.

Dudok de Wit, T.

2011-09-01

168

A new approach to the long-term reconstruction of the solar irradiance leads to large historical solar forcing  

NASA Astrophysics Data System (ADS)

Context. The variable Sun is the most likely candidate for the natural forcing of past climate changes on time scales of 50 to 1000 years. Evidence for this understanding is that the terrestrial climate correlates positively with the solar activity. During the past 10 000 years, the Sun has experienced the substantial variations in activity and there have been numerous attempts to reconstruct solar irradiance. While there is general agreement on how solar forcing varied during the last several hundred years - all reconstructions are proportional to the solar activity - there is scientific controversy on the magnitude of solar forcing. Aims: We present a reconstruction of the total and spectral solar irradiance covering 130 nm-10 ?m from 1610 to the present with an annual resolution and for the Holocene with a 22-year resolution. Methods: We assume that the minimum state of the quiet Sun in time corresponds to the observed quietest area on the present Sun. Then we use available long-term proxies of the solar activity, which are 10Be isotope concentrations in ice cores and 22-year smoothed neutron monitor data, to interpolate between the present quiet Sun and the minimum state of the quiet Sun. This determines the long-term trend in the solar variability, which is then superposed with the 11-year activity cycle calculated from the sunspot number. The time-dependent solar spectral irradiance from about 7000 BC to the present is then derived using a state-of-the-art radiation code. Results: We derive a total and spectral solar irradiance that was substantially lower during the Maunder minimum than the one observed today. The difference is remarkably larger than other estimations published in the recent literature. The magnitude of the solar UV variability, which indirectly affects the climate, is also found to exceed previous estimates.We discuss in detail the assumptions that lead us to this conclusion. Appendix is only available in electronic form at http://www.aanda.org

Shapiro, A. I.; Schmutz, W.; Rozanov, E.; Schoell, M.; Haberreiter, M.; Shapiro, A. V.; Nyeki, S.

2011-05-01

169

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

PubMed

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

Junk, Jürgen; Feister, Uwe; Helbig, Alfred

2007-02-22

170

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

171

Hegel, Analogy, and Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

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

Ross, Joseph T.

172

NOAA 11 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument solar spectral irradiance measurements in 1989-1994 2. Results, validation, and comparisons  

NASA Astrophysics Data System (ADS)

Accurately measuring long-term solar UV variability is an experimental challenge because instrument response degradations are typically large enough to obscure solar change. For satellite instruments, one solution is a series of regular comparisons with a well-calibrated reference. The NOAA 11 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument made solar spectral irradiance measurements between 170 and 400 nm from December 1988 to October 1994, covering the maximum and most of the decline of solar cycle 22. The NOAA 11 irradiance data were corrected for long-term instrument sensitivity changes using comparisons with coincident flights of the Shuttle SBUV (SSBUV) instrument. The NOAA 11 data show a decrease of 7.0(+/-1.8)% in smoothed 200-208 nm irradiance from Cycle 22 maximum in mid-1989 to October 1994, near solar minimum. The long-term decrease in solar irradiance at 250 nm was ~3.5(+/-1.8)%. Longward of 300 nm, no solar variations were observed to within the 1% accuracy of the data. The NOAA 11 measurements overlap observations from the Upper Atmosphere Research Satellite (UARS) Solar Stellar Irradiance Comparison Experiment (SOLSTICE) and Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) instruments from October 1991 to October 1994, providing the first opportunity to compare three coincident long-term solar UV irradiance data sets. We find reasonable agreement between the NOAA 11, SOLSTICE, and SUSIM results at all wavelengths in the 170-400 nm region. Power spectral analysis gives consistent results for all three instruments on solar rotational timescales, and reveals the evolution of solar rotation periodicity and strength during a solar cycle. We find significant differences between instruments in both period and spectral location when the spectral irradiance data are analyzed on intermediate (50-250 days) timescales. The NOAA 11 spectral irradiance data provide a valuable complement to the UARS solar data, and capture the entire maximum of solar cycle 22.

DeLand, Matthew T.; Cebula, Richard P.

1998-07-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

174

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

175

Towards a long-term record of solar total and spectral irradiance  

NASA Astrophysics Data System (ADS)

The variation of total solar irradiance (TSI) has been measured since 1978 and that of the spectral irradiance for an even shorter amount of time. Semi-empirical models are now available that reproduce over 80% of the measured irradiance variations. An extension of these models into the more distant past is needed in order to serve as input to climate simulations. Here we review our most recent efforts to model solar total and spectral irradiance on time scales from days to centuries and even longer. Solar spectral irradiance has been reconstructed since 1947. Reconstruction of solar total irradiance goes back to 1610 and suggests a value of about 1-1.5W/m2 for the increase in the cycle-averaged TSI since the end of the Maunder minimum, which is significantly lower than previously assumed but agrees with other modern models. First steps have also been made towards reconstructions of solar total and spectral irradiance on time scales of millennia.

Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.

2011-02-01

176

Universalist ethics in extraterrestrial encounter  

NASA Astrophysics Data System (ADS)

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

Baum, Seth D.

2010-02-01

177

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

178

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

179

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

PubMed

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

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

2010-03-04

180

Estimating Integrated Cloud Liquid Water from Extended Time Observations of Solar Irradiance.  

National Technical Information Service (NTIS)

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 sam...

C. W. Fairall R. E. Rabadi J. B. Snider

1990-01-01

181

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

National Technical Information Service (NTIS)

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

J. D. Broder S. J. Marsik

1975-01-01

182

Modelling solar irradiance variations with an area dependent photometric sunspot index  

Microsoft Academic Search

The He 1083 nm line equivalent width and the 10.7 cm radio flux are employed to model the total solar irradiance corrected for sunspot deficit. A new “area dependent photometric sunspot index” (APSI) based on sunspot photometry by Steinegger et al. (1990) is used to correct the irradiance data for sunspot deficits. Two periods of time are investigated: firstly, the

P. N. Brandt; M. Stix; H. Weinhardt

1994-01-01

183

Modeling solar irradiance variations with an area dependent photometric sunspot index  

Microsoft Academic Search

The He 1083 nm line equivalent width and the 10.7 cm radio flux are employed to model the total solar irradiance corrected for sunspot deficit. A new `area dependent photometric sunspot index' (APSI) based on sunspot photometry by Steinegger et al. (1990) is used to correct the irradiance data for sunspot deficits. Two periods of time are investigated: firstly, the

P. N. Brandt; M. Stix; H. Weinhardt

1994-01-01

184

Measurement of Solar Spectral Irradiances at Wavelengths Between 40 and 4000 A.  

National Technical Information Service (NTIS)

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 measureme...

J. G. Timothy

1983-01-01

185

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

Microsoft Academic Search

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

M. Nicolet

1981-01-01

186

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

Microsoft Academic Search

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

Ivonete Rossi Bautitz; Raquel F. Pupo Nogueira

2007-01-01

187

Combined Analysis of Solar Neutrino and Solar Irradiance Data: Further Evidence for Variability of the Solar Neutrino Flux and Its Implications Concerning the Solar Core  

NASA Astrophysics Data System (ADS)

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

Sturrock, P. A.

2009-02-01

188

Comparison of model estimated and measured direct-normal solar irradiance  

Microsoft Academic Search

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

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

1997-01-01

189

Measured and modeled solar spectral irradiance and absorption for TC4 ice and water cloud scenes  

NASA Astrophysics Data System (ADS)

The TC4 experiment provided extensive coordinated above- and below-cloud measurements of solar spectral irradiance (Solar Spectral Flux Radiometer) onboard the NASA ER-2 and DC-8 aircraft, which also carried various active and passive cloud remote sensing as well as in-situ cloud instrumentation. We present measured spectral irradiance and absorption along coordinated flight legs for water and ice clouds. We derive effective radius from reflected and absorbed irradiance along those legs and relate those to CAPS (Cloud Aerosol and Precipitation Spectrometer) in-situ measurements onboard the DC-8 and to retrievals from MAS (MODIS Airborne Simulator) and MASTER (MODIS and ASTER Airborne Simulator) onboard the ER-2.

Wind, G.; Schmidt, S.; Pilewskie, P.; King, M.; Bansemer, A.; Kindel, B.; McBride, P.

2007-12-01

190

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

191

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

192

The role of extraterrestrial phenomena in extinction.  

PubMed

In the several years since the Alvarez report of anomalously high iridium concentrations at the Cretaceous-Tertiary boundary, evidence for the involvement of meteorite impacts in biological extinction has increased dramatically. Much more research will be needed, however, before meteorite impact is established as a general causal factor in extinction. Of ever greater long-term interest is the possibility that other extraterrestrial forces have had important influences on the evolution of life. To recognize the effects of such forces, it will be necessary to coordinate the research of astronomy and paleontology so that testable predictions can be formulated. It is possible that known, systematic changes in the Solar System or Galaxy have had effects on global biology and that these effects have been preserved in the paleontological record. PMID:11542144

Raup, D M

1988-01-01

193

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

NASA Astrophysics Data System (ADS)

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

Foukal, P.; Spruit, H.

2004-12-01

194

A Comparison of the First Solar EUV Irradiance Measurements from the SDO/EVE EUV Spectrophotometer (ESP) with the SOHO/CELIAS Solar EUV Monitor (SEM) Absolute Solar EUV Irradiance  

NASA Astrophysics Data System (ADS)

First light measurements from the SDO/EVE EUV Spectrophotometer (ESP) are calibrated based on both ESP pre-flight radiometric calibration and the SDO EVE calibration rocket un-derflight (5 May 2010) measurements obtained with the ESP and Multiple EUV Grating Spec-trometers (MEGS), which are clones of the SDO EVE onboard instruments. SDO/EVE/ESP absolute solar EUV irradiances are compared with the SOHO/CELIAS Solar EUV Monitor (SEM) data to provide uninterrupted EUV measurements of solar irradiances since 1996. The continuing EUV measurements from SDO/EVE/ESP will advance our study of long-and short-term solar EUV variability, improve existing solar EUV irradiance models, and use as input for improving ionosphere and thermosphere model results.

Didkovsky, Leonid; Judge, Darrell; Wieman, Seth; Woods, Thomas; Eparvier, Francis; Jones, Andrew

195

Extraterrestrial resources - A metallogenical typology  

NASA Astrophysics Data System (ADS)

It is noted that numerous extraterrestrial exploration programs have been suggested since the end of the 1980's. A properly defined classification of the objectives will be needed if this exploration is to be organized in a rational manner. A metallogenic study could lead to a typology of these resources, permitting the objectives of long term exploration to be hierarchically sorted.

Giannoni, A.

196

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

197

The Search for Extraterrestrial Intelligence.  

ERIC Educational Resources Information Center

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

Jones, Barrie W.

2003-01-01

198

Extraterrestrial Matter Chronometry of Sediments  

Microsoft Academic Search

Tracer records of extraterrestrial matter (ET) accumulation in sediments suggest that ET accretion rates are reasonable constant on time scales relevant to sediment accumulation in terrestrial and marine environments (1000-100,000 years), except during impact events. Geochemical tracers of ET matter in sediments are therefore informative rate indicators applicable to individual samples. This alleviates the need for interpolating rates between known

B. Peucker-Ehrenbrink; C. A. Waters; P. F. Hoffman; M. D. Kurz

2010-01-01

199

Duties to Extraterrestrial Microscopic Organisms  

NASA Astrophysics Data System (ADS)

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

Cockell, C. S.

200

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

201

Towards a Solar Cycle Average Model for Heliospheric Irradiation of Small Icy Bodies in the Outer Solar System  

NASA Astrophysics Data System (ADS)

Abundant data are available from operational interplanetary spacecraft to construct model flux spectra and dosage profiles for irradiation of icy bodies including Centaurs, Kuiper Belt Objects, and Oort Cloud comets by ions at plasma to cosmic ray energies. Data sources include the Advanced Composition Explorer (ACE) and other spacecraft in interplanetary space near Earth, the Ulysses spacecraft in an eccentric six-year polar orbit around the Sun, and the two Voyager spacecraft now moving through the outer Solar System towards the boundaries of the heliosphere. For applications to irradiation of solar system objects there is a need to compile flux averages of past and future data extending over the 11-year solar activity cycle, and the 22-year solar magnetic cycle, as approximations to irradiation over much longer periods of time. Heliospheric plasma and cosmic ray transport models can be used to extrapolate from multiple spacecraft observation points to heliocentric orbits of specific bodies at given phases of these cycles. In this report we focus on interstellar pickup ions accelerated from initial plasma (eV - keV) energies up to 100 MeV/nucleon at the solar wind termination shock, thought to be located at 90 - 100 AU from the Sun, and propagated by diffusion and gradient-curvature drifts throughout the heliosphere. These ions show large changes in intensity and spatial gradients during both cycles, while being very important for surface irradiation of small bodies in the outer solar system. Overall positive radial gradients are predicted for ACR ion intensities averaged over 22 years at orbits of Centaurs and KBOs, possibly contributing to perihelion and eccentricity gradients in visible color of the Classical KBO population. Compression of heliospheric boundaries inward in response to increasing density of local interstellar gas could occasionally expose these objects to stronger radial gradients and higher irradiation dosages over billions of years.

Cooper, J. F.; Cummings, A. C.; Mewaldt, R. A.; Richardson, J. D.; Wang, C.; Johnson, R. E.

2003-05-01

202

Discharge phenomenon on solar array surface due to RF irradiation  

Microsoft Academic Search

Space solar power system (SSPS) transfers enormous amount of electrical energy of microwave. As the microwave may diffract to solar array surface, there is concern of multipactor discharge caused by the microwave. There has been no experiment on interaction between high intensity microwave and solar array. The verification experiment is essential for SSPS to become a reality. We examined interaction

K. Kasedo; S. Hosoda; K. Toyoda; Mengu Cho; Y. Hisada

2006-01-01

203

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

204

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

205

Solar Irradiance Reference Spectra (SIRS) for the 2008 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 Extreme ultraviolet Experiment (SEE) and Solar Radiation and Climate Experiment (SORCE) instruments. The extreme ultraviolet range is also improved with higher spectral resolution observations using the prototype SDO Extreme ultraviolet Variability Experiment (EVE) aboard a sounding rocket launched on 14 April 2008. The SIRS result is an important accomplishment in that it is the first data set to have simultaneous measurements over the full spectral coverage up to 2400 nm during solar cycle minimum conditions.

Woods, Thomas N.; Chamberlin, Phillip C.; Harder, Jerald W.; Hock, Rachel A.; Snow, Martin; Eparvier, Francis G.; Fontenla, Juan; McClintock, William E.; Richard, Erik C.

2009-01-01

206

Extraterrestrial Mössbauer spectrometry  

NASA Astrophysics Data System (ADS)

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

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

1992-05-01

207

Extraterrestrial Mössbauer spectrometry.  

NASA Astrophysics Data System (ADS)

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

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

1992-05-01

208

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

NASA Astrophysics Data System (ADS)

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

Parker, Daryl Gray

209

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

210

Solar UV Spectral Irradiance Measurements at 0.15 nm Resolution by SUSIM  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

211

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

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

212

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

SciTech Connect

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

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

2010-09-15

213

Solar uv irradiance, its variation, and its relevance to the earth  

NASA Astrophysics Data System (ADS)

Originating in the sun's upper photosphere, chromosphere, transition zone, and corona, solar UV (including EUV) emissions have a profound effect on Earth's ionosphere, thermosphere, mesosphere, and stratosphere. Through ionization, dissociation and excitation processes, solar UV is the primary source of energy input to the atmosphere and, as a result, it plays a central role in the atmosphere's vertical, thermal, and electronic structure. Further, the solar UV irradiance is a principal driver of the strong dynamics in the atmosphere and its cycles of chemical species, especially those of nitrogen and oxygen. Over the past three decades, numerous space-based measurements of solar UV light have been made in order to better understand its nature and effects. They show that the UV irradiance does varies through time, primarily on 27-day solar rotation and 11-year solar cycle time scales, and that this wavelength-dependent variation is primarily associated with the emergence, growth, and decay of active regions on the solar disk. Numerous models and proxies have been developed with some success to better understand and predict solar UV variations and their wavelength dependence. However, in spite of considerable progress, the present estimates of solar variability together with atmospheric models still do not provide complete and accurate descriptions of atmospheric phenomena. Acordingly, we cannot be sure that the accuracy of current measurements is sufficient. Moreover, in some cases, correlation studies of both atmosphere and climate, imply that solar variations are more important than physics-based models would indicate. We discuss the current international UV irradiance measurement and modeling program and make recommendations about its continuation. Also, we outline some evidence for and possible causes of a solar connection in the evolution of atmosphere and climate.

Floyd, Linton; Tobiska, W. Kent; Cebula, Richard P.

214

Searching for extraterrestrial artifacts.  

NASA Astrophysics Data System (ADS)

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

Freitas, R. A.

215

Extraterrestrial Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

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

Klingelhöfer, Göstar

216

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

217

Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation  

NASA Astrophysics Data System (ADS)

The impact of NOx and HOx production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

Semeniuk, K.; Fomichev, V. I.; McConnell, J. C.; Fu, C.; Melo, S. M. L.; Usoskin, I. G.

2011-05-01

218

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

219

Extraterrestrial life contradicts dark energy  

NASA Astrophysics Data System (ADS)

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

Gibson, Carl H.

2012-10-01

220

A classification of extraterrestrial cultures  

NASA Astrophysics Data System (ADS)

A novel classification of the forms that an extraterrestrial culture might take is made, the classification being based on well-established physical principles as an aid in the search for extraterrestrial intelligences. The most popular current classification (Kardeshev, 1964), which has three divisions identified by the energy consumption of the culture, is critically examined. The new classification of the technically developing cultures, based on the energy sources that a culture has harnessed, is described in detail. It is assumed that all intelligent species evolved on or near the surface of planets similar to the earth in that they are part of the inner system of a stable star and possess a hard surface. Areas of activity (e.g., favorable surface conditions, nearby planetary systems, widespread in the Galaxy), energy sources (e.g., unmodified and modified surface sources, fusion of all light isotopes, annihilation of matter), and primary energy sources (e.g., local primary, ancient supernova events, later and early stages of 'Big Bang') are examined for the six classes of civilization. Inferences, that might suggest improved approaches to the current searches for extraterrestrial intelligences, are drawn from the proposed classification.

Stephenson, D. G.

1981-11-01

221

Influence of scattering phenomena on the solar zenith angle dependence of in-water irradiance levels  

SciTech Connect

A Monte Carlo analysis is utilized to determine the influence of the inherent properties of a water mass on the solar zenith angle dependence of subsurface irradiance levels. It is shown that the proportion of scattering interactions (as represented by the scattering albedo ..omega..) has a greater influence on this dependence that does the backscattering probability B. Several representations of direct and/or diffuse incident radiation are considered, and their effects on the solar zenith angle dependence are evaluated. Irradiance level data collected in Lake Erie are compared to the predictions of the Monte Carlo analysis.

Jerome, J.H.; Bruton, J.E.; Bukata, R.P.

1982-02-15

222

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

NASA Astrophysics Data System (ADS)

This study focuses on the design of an automatic algorithm for classification of the cloudiness condition based only on global irradiance measurements. Clouds are a major modulating factor for the Earth radiation budget. They attenuate the solar radiation and control the terrestrial radiation participating in the energy balance. Generally, cloudiness is a limiting factor for the solar radiation reaching the ground, highly contributing to the Earth albedo. Additionally it is the main responsible for the high variability shown by the downward irradiance measured at ground level. Being a major source for the attenuation and high-frequency variability of the solar radiation available for energy purposes in solar power plants, the characterization of the cloudiness condition is of great interest. This importance is even higher in Southern Europe, where very high irradiation values are reached during long periods within the year. Thus, several indexes have been proposed in the literature for the characterization of the cloudiness condition of the sky. Among these indexes, those exclusively involving global irradiance are of special interest since this variable is the most widely available measurement in most radiometric stations. Taking this into account, this study proposes an automatic algorithm for classifying the cloudiness condition of the sky into three categories: cloud-free, partially cloudy and overcast. For that aim, solar global irradiance was measured by Kipp&Zonen CMP11 pyranometer installed on the terrace of the Physics building in the Campus of Badajoz (Spain) of the University of Extremadura. Measurements were recorded at one-minute basis for a period of study extending from 23 November 2009 to 31 March 2010. The algorithm is based on the clearness index kt, which is calculated as the ratio between the solar global downward irradiance measured at ground and the solar downward irradiance at the top of the atmosphere. Since partially cloudy conditions exhibit large variability in the solar global irradiance measured at ground and, therefore, in the kt index, the algorithm is based, along with the value of the kt index, on the local variability. This variability was locally computed as the coefficient of variation of a two-neighbor window around each measurement. The consideration of both, the value of kt index and its local variability, highly improves previous classifications consisting in applying fixed thresholds to the kt index value. The proposed algorithm is applied to certain selected cases and compared to classifications proposed by other authors.

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

2010-09-01

223

Solar Irradiance Variations in the Visible and Infrared:Comparison of the SORCE SIM instrument to the RISE model  

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. The SIM observations will be compared with concurrent computations of the solar spectral irradiance generated from the RISE (Radiative Inputs from the Sun to the Earth) synthesis code with decompositions of PSPT (Precision Solar Photometric Telescope) images. This irradiance synthesis directly accounts for the distribution and evolution of features on the Sun that contribute to irradiance variations. The RISE method uses seven solar atmospheric models (Fontenla, Avrett, and Loeser, ApJ, 406, 319, 1993) to represent sunspots, plage, network, and quiet atmosphere. The contributions of these seven atmospheric models are then weighted according to the decomposition of the solar images. Time series comparisons at visible wavelengths between the model and the SIM observations indicate good agreement. However, current models of IR spectral irradiance are inaccurate at long wavelengths; this behavior is due to the fact that, contrary to the current model assumptions, the presence of active regions on the solar disk increase the spectral irradiance at all wavelengths even near the opacity minimum at 1.6 microns in a manner similar to the observed TSI. Consequently, calculations of solar spectral irradiance at wavelengths near 1.6 microns need to be revised to match the observed solar irradiance.

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

2004-05-01

224

A comparison of variable solar total and ultraviolet irradiance outputs in the 20th century  

Microsoft Academic Search

Differences in time- variation between total and ultraviolet solar irradiance could help in separating their influence on climate. We present the first models based on area measurements of magnetic plages from CaK spectroheliograms obtained between 1915-1999. Correlation of our time series of UV irradiance with global temperature, T, accounts for only 20% of the global temperature variance during the 20th

Peter Foukal

2002-01-01

225

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

Microsoft Academic Search

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

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

226

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

Microsoft Academic Search

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

J. G. Timothy

1983-01-01

227

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

Microsoft Academic Search

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

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

1996-01-01

228

Basic study on the prediction of solar irradiation and its application to photovoltaic-diesel hybrid generation system  

Microsoft Academic Search

This paper at first describes a basic study on the prediction of hourly or daily amount of solar irradiation. The method is based on theoretical equation and observation of solar irradiance. Then, the novel method to control photovoltaic-diesel hybrid generation system using the prediction is proposed to improve the total efficiency of the system. A numerical simulation result shows the

Shigehiro Yamamoto; Jae-Shik Park; Masahiko Takata; Koichiro Sasaki; Takeshi Hashimoto

2003-01-01

229

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

Microsoft Academic Search

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

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

2007-01-01

230

The moral status of extraterrestrial life.  

PubMed

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

Persson, Erik

2012-09-26

231

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

Microsoft Academic Search

Within the framework of the ENVISAT\\/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV\\/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA\\/DOAS balloon gondola at around 32 km balloon

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

2004-01-01

232

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

Microsoft Academic Search

Within the framework of the ENVISAT\\/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV\\/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA\\/DOAS balloon gondola at around 32 km balloon

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

2005-01-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

234

Modeling solar irradiance variations through PSPT images and semiempirical models  

NASA Astrophysics Data System (ADS)

We try to reconstruct the variations of the disk integrated spectrum, both in the spectral ranges of VIRGO (blue at 403 nm, green at 501 nm and red at 863 nm) and in the bolometric flux, using semiempirical models (FAL models, Fontenla et al. 1999), built to reproduce different features in the solar atmosphere. Each computed spectrum is weighted with the disk coverage factor of the corresponding feature provided by the PSPT observations carried out at the Rome Observatory. We present the results obtained reconstructing the variations measured by VIRGO bolometers during periods of about one solar rotation and of the entire ascending phase of Solar Cycle 23.

Penza, V.; Caccin, B.; Ermolli, I.; Centrone, M.; Gomez, M. T.

2003-09-01

235

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

NASA Astrophysics Data System (ADS)

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

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

236

Influence of crystal tilt on solar irradiance of cirrus clouds.  

PubMed

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

Klotzsche, Susann; Macke, Andreas

2006-02-10

237

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

NASA Astrophysics Data System (ADS)

This work is a part of ESA/EU SURE project aiming to quantify the survival probability of fungal spores in space under solar irradiation in the vacuum ultraviolet (VUV) (110-180 nm) spectral region. The contribution and impact of VUV photons, vacuum, low temperature and their synergies on the survival probability of Aspergillus terreus spores is measured at simulated space conditions on Earth. To simulate the solar VUV irradiation, the spores are irradiated with a continuous discharge VUV hydrogen photon source and a molecular fluorine laser, at low and high photon intensities at 1015 photon m-2 s-1 and 3.9×1027 photons pulse-1 m-2 s-1, respectively. The survival probability of spores is independent from the intensity and the fluence of photons, within certain limits, in agreement with previous studies. The spores are shielded from a thin carbon layer, which is formed quickly on the external surface of the proteinaceous membrane at higher photon intensities at the start of the VUV irradiation. Extrapolating the results in space conditions, for an interplanetary direct transfer orbit from Mars to Earth, the spores will be irradiated with 3.3×1021 solar VUV photons m-2. This photon fluence is equivalent to the irradiation of spores on Earth with 54 laser pulses with an experimental ˜92% survival probability, disregarding the contribution of space vacuum and low temperature, or to continuous solar VUV irradiation for 38 days in space near the Earth with an extrapolated ˜61% survival probability. The experimental results indicate that the damage of spores is mainly from the dehydration stress in vacuum. The high survival probability after 4 days in vacuum (˜34%) is due to the exudation of proteins on the external membrane, thus preventing further dehydration of spores. In addition, the survival probability is increasing to ˜54% at 10 K with 0.12 K/s cooling and heating rates.

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

2011-01-01

238

Low temperature quantum efficiency measurements on irradiated multijunction solar cells  

Microsoft Academic Search

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

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

2008-01-01

239

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

240

New developments in solar irradiance proxies for operational space weather  

Microsoft Academic Search

Six new solar proxies have been developed in the past two years in support of a sec- ond-generation forecasting capability. These proxies help characterize the energy input into op- erational space physics models. In addition to hourly-to-daily forecasts that produce a full solar spectrum used in numerical atmospheric and ionospheric models relevant to climatological stud- ies, the E10.7 index is

W. Kent Tobiska

2002-01-01

241

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

242

A simple method for estimating solar irradiation on inclined surface at any location using data analysis techniques  

Microsoft Academic Search

This paper proposes a simple method for estimating the monthly global hourly solar irradiation (GHSI) on an inclined surface at any location. The method employs simple analytical solar position and GHSI calculation models to calculate the Sun's position at any solar time and the GHSI in clear?sky condition for both horizontal and inclined surfaces at any target location, respectively. Then,

2010-01-01

243

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

Microsoft Academic Search

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

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

2004-01-01

244

Electron irradiation damage in radiation-resistant InP solar cells  

Microsoft Academic Search

Minority carrier diffusion length and carrier concentration studies on defects induced by 1 MeV electron irradiation in InP solar cells have been examined, and the correlation between the measured defect parameters and the performance characteristics of the cells has been elucidated. Decreases in carrier concentration and minority carrier diffusion are the causes of performance degradation in cells with low and

Masafumi Yamaguchi; Chikao Uemura; Akio Yamamoto; Atsushi Shibukawa

1984-01-01

245

Estimating surface solar irradiance from METEOSAT SEVIRI-derived cloud properties  

Microsoft Academic Search

A satellite retrieval of surface solar irradiance based on METEOSAT SEVIRI-derived cloud properties is presented and validated for the Netherlands with one year of pyranometer measurements from 35 stations. The approach requires two independent steps: 1. Cloud properties are determined from narrow-band satellite radiances. 2. These cloud properties are used together with data on water vapor column and surface albedo

H. M. Deneke; A. J. Feijt; R. A. Roebeling

2008-01-01

246

Photocatalytic degradation of phenol under solar radiation using microwave irradiated zinc oxide  

Microsoft Academic Search

The effect of preparation method on the photocatalytic degradation of phenol using zinc oxides under solar radiation was studied in batch reactors. Zinc oxide was prepared by different methods by varying precipitating agents and the source of precursors and microwave irradiation time and characterized by XRD, surface area, acid sites and crystallite sizes. The photocatalytic reactions were carried out by

K. M. Parida; S. Parija

2006-01-01

247

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

Microsoft Academic Search

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

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

2005-01-01

248

Quantification of solar irradiation caused by restrictions or extensions of the horizon  

NASA Astrophysics Data System (ADS)

The First Technical Report of the intended research project 'Development of a Measuring Equipment for the Quantification of Solar Irradiation Reductions caused by Restrictions of the Horizon' contains fundamental ideas for a realization of this project. Based on a description of the main objectives of this project and a subsequent critical review of present procedures, used for the determination of shading effects, three technical possibilities to realize the hardware are pointed out. In view of this, main advantages and disadvantages of these are discussed. In order to understand the substantial steps of these procedures, the most important operational principles of some of the components are described in detail. The subsequent comparative assessment, considering the expenditure of maintenance and development, the use of commercial components, the compactness of arrangements as well as the costs, leads to the selection of a suitable measuring equipment. The software development is described in the third chapter of this report. Different kinds of possibilities to generate hourly data of solar irradiation on horizontal surfaces (clear horizon) are discussed, regarding their usefulness within this project. Restrictions of the horizon have an influence on direct and diffuse solar irradiation. The related various effects are presented shortly. Furthermore, difficulties in calculating solar irradiation on arbitrary inclined and orientated surfaces are explained.

Skiba, M.; Mohr, M.; Unger, H.

1995-01-01

249

Space Observations of the Variability of Solar Irradiance in the Near and Far Ultraviolet.  

National Technical Information Service (NTIS)

Satellite observations of the ultraviolet solar irradiance in selected wavelength bands between 1200 and 3000 a were made continuously by photometers consisting of broad-band sensors operated on Numbus 3 and 4 which were launched in April 1969 and 1970. I...

D. F. Heath

1972-01-01

250

Solar EUV and X-ray Irradiance: Recent Results and New Prospects  

Microsoft Academic Search

Solar irradiance in the vacuum ultraviolet and X-ray regions of the spectrum creates planetary ionospheres and thermospheres, and is the most important source of their variability. Accurate measurements of the far ultraviolet are available, but spectrally resolved extreme ultraviolet and soft X-ray estimates have relied on older, variously calibrated observations. Recent broadband measurements by the SNOE satellite have revealed that

T. N. Woods; S. C. Solomon; S. M. Bailey

2001-01-01

251

Remote sensing of surface solar irradiance with corrections for 3-D cloud effects  

Microsoft Academic Search

Surface solar irradiance (ISFC) can be inferred from satellite-observed radiance with retrieval algorithms based on the independent pixel approximation (IPA). As the spatial resolution of satellite sensors increases, the effects from spatially inhomogeneous cloud fields become more important. Clouds affect the distribution of radiation in a region larger than the resolution of an individual pixel and IPA is no longer

Klaus Wyser; William O'Hirok; Catherine Gautier; Charles Jones

2002-01-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

253

Middle Atmosphere Response to Different Descriptions of the 11-Year Solar Cycle in Spectral Irradiance in a Chemistry-Climate Model.  

National Technical Information Service (NTIS)

The 11-year solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone ...

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

2012-01-01

254

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

255

The spectral effects of clouds on solar irradiance  

NASA Astrophysics Data System (ADS)

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

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

1998-12-01

256

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

NASA Astrophysics Data System (ADS)

The Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) measures solar spectral variability in the 200-2400 nm range accounting for about 97% of the total solar irradiance (TSI). SIM concurrently measures ultraviolet variability from 200-310 nm with the higher spectral resolution Solar-Stellar Irradiance Comparison Experiment (SOLSTICE). These instruments monitored the descending phase of solar cycle 23 and are now continuing these observations in the rising phase of cycle 24. SIM and SOLSTICE observations clearly show rotational modulation of spectral irradiance due to the evolution of dark sunspots and bright faculae that respectively deplete and enhance solar radiation. In addition to this well-known phenomenon, SORCE observations indicate a slower evolutionary trend in solar spectral irradiance (SSI) over solar cycle time-scales that are both in and out of phase with the TSI, with the ultraviolet component indicating significantly larger UV variability than reported from the UARS era instruments. Wavelengths where the brightness temperature is less than Teff = 5770 K are in phase, and where the brightness temperature > Teff in the visible and infrared, the time series show an anti-solar cycle trend. This observation is discussed in terms of the Solar Radiation Physical Modeling (SRPM) program employing solar images from Precision Solar Photometric Telescope (PSPT) that provides the areas of active regions on the solar disk as function of time to generate a modeled SSI time series that is concurrent with the SORCE observations but extending back to solar maximum conditions. Comparative studies of the SIM and SOLSTICE will be presented along with analysis of solar variability derived from SRPM and PSPT.

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

2011-12-01

257

Observations of the solar soft X-ray irradiance by the student nitric oxide explorer  

NASA Astrophysics Data System (ADS)

The student nitric oxide explorer (SNOE) satellite made daily solar observations of the solar soft X-ray irradiance over most of the period from March 10, 1998 through March 16, 2002. Wavelengths below 30 nm, referred to as soft X-rays, were measured in broadband channels consisting of photodiodes with thin film filters deposited directly on the diode surfaces. SNOE had three such channels measuring in the bands 0.1 7, 6 19 , and 17 20 nm. The solar rotational (˜27-day) variability in these bands is 44%, 28%, and 14%, respectively, and the solar cycle (11-year) variability is approximately factors of 11, 6 and 5, respectively. The SNOE observations are compared to more recent observations by the TIMED SEE instrument which uses the same technique at similar levels of solar activity and are found to be larger by a factor nearing two. The SNOE observations are shown however to be in excellent agreement with the EUVAC empirical model of solar irradiance.

Bailey, Scott M.; Woods, Thomas N.; Eparvier, Francis G.; Solomon, Stanley C.

258

Variability in the solar constant from irradiances shortward of Lyman-Alpha  

NASA Astrophysics Data System (ADS)

The variation in the solar constant, S(t), is reproduced by the SOLAR2000 Research Grade v1.05 empirical solar irradiance model and is described for 5 solar cycles between cycles 18 and 23 (February 14, 1947 through May 31, 2000). This solar constant variation is dependent upon the derivation data sets and the formulation of SOLAR2000 which are described in more detail. The S(t) temporal variability in SOLAR2000 is shown for the solar spectrum between 1-122 nm. The variability is consistent with previous discussions in the literature and a new result is shown where the 1-122 nm wavelength range accounts for about 5-14% of the standard deviation reported in the ASTM E-490 standard. The minimum-maximum range of S(t) variation due to 1-122 nm variability is between 1367.2768 Wm-2 on 1986-152 and 1367.2877 Wm-2 on 1957-340. The mean S(t) in these data is 1367.2796 Wm-2.

Tobiska, W. Kent

259

Optical Search for Extraterrestrial Intelligence with Air Cerenkov Telescopes  

NASA Astrophysics Data System (ADS)

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

Eichler, David; Beskin, Gregory

2001-12-01

260

Comparison of shadow-ring correction models for diffuse solar irradiance  

NASA Astrophysics Data System (ADS)

Reliable and accurate measurements of diffuse solar irradiance are needed in order to partition global irradiance into its direct and diffuse components. Diffuse irradiance is commonly measured using sun tracking systems or shadow rings. Data obtained using a shadow ring must be corrected for the portion of diffuse irradiance blocked by the ring. In this paper we have examined and evaluated six of the most widely used correction models. Approaches that account for radiation anisotropy perform notably better than those using only geometric corrections. Our results also argue for the need to adjust empirical models to local conditions. Empirical approaches developed by LeBaron et al. (1990) and by Batlles et al. (1995) perform best when compared with the more theoretical models.

SáNchez, G.; Serrano, A.; Cancillo, M. L.; GarcíA, J. A.

2012-05-01

261

Detailed defect study in proton irradiated InP/Si solar cells  

NASA Astrophysics Data System (ADS)

A detailed study of the effects of proton irradiation-induced defects in heteroepitaxially grown InP/Si solar cells has been made through a combination of cathodoluminescence (CL), electron beam induced current (EBIC), and electrochemical capacitance versus voltage (ECV) carrier profiling measurements. The CL data indicate the distribution of nonradiative recombination centers both before and after proton irradiation, and temperature dependent and spectroscopic analysis of the CL signal give an estimate of the energies of the dominant defect levels. The EBIC data yield an estimate of the magnitude and spatial variation of the minority carrier diffusion length (L) in the base region. Values of L determined from EBIC measurements made on solar cells irradiated by protons ranging in energy from 0.1 up to 4.5 MeV follow a single curve when plotted versus displacement dose, Dd, allowing a single proton damage coefficient to be determined. The ECV measurements show the evolution of the carrier concentration profile in the cell under irradiation, as carrier removal first depletes and eventually type converts the base region. From an in-depth analysis of the combined data, the physical defects that give rise the radiation-induced energy levels are suggested, and a detailed understanding of the physical mechanisms causing the radiation response of InP/Si solar cells is developed.

Walters, R. J.; Romero, M. J.; Araújo, D.; García, R.; Messenger, S. R.; Summers, G. P.

1999-10-01

262

Towards the reconstruction of the EUV irradiance for solar Cycle 23  

NASA Astrophysics Data System (ADS)

We present preliminary reconstructions of the EUV from 26 to 34 nm from February 1997 to May 2005, covering most of solar cycle 23. The reconstruction is based on synthetic EUV spectra calculated with the spectral synthesis code Solar Modeling in 3D (SolMod3D). These spectra are weighted by the relative area coverage of the coronal features as identified from EIT images. The calculations are based on one-dimensional atmospheric structures that represent a temporal and spatial mean of the chromosphere, transition region, and corona. The employed segmentation analysis considers coronal holes, the quiet corona, and active regions identified on the solar disk. The reconstructed EUV irradiance shows a good agreement with observations taken with the CELIAS/SEM instrument onboard SOHO. Further improvement of the reconstruction including more solar features as well as the off-limb detection of activity features will be addressed in the near future.

Haberreiter, Margit

2012-07-01

263

The need for operating guidelines and a decision making framework applicable to the discovery of non-intelligent extraterrestrial life  

Microsoft Academic Search

While formal principles have been adopted for the eventuality of detecting intelligent life in our galaxy (SETI Principles), no such guidelines exist for the discovery of non-intelligent extraterrestrial life within the solar system. Current scientifically based planetary protection policies for solar system exploration address how to undertake exploration, but do not provide clear guidance on what to do if and

Margaret S. Race; Richard O. Randolph

2002-01-01

264

Solar Irradiance of the Earth’s Atmosphere  

Microsoft Academic Search

\\u000a The sun is the primary driver of terrestrial atmospheric phenomena and energy source for the earth. It emits radiation over\\u000a a large energy band and ejects highly energetic plasma fluxes of charged particles into space. The sun is an active star that\\u000a (i) goes through a 12-year maximum–minimum emission cycle, (ii) has huge, non-periodic eruptions in solar flares and coronal

Sultana N. Nahar

265

Solar Irradiance: a Key to the Earth's Ionosphere and Thermosphere  

Microsoft Academic Search

Solar radiation at extreme ultraviolet (EUV) wavelengths creates the ionosphere and is re-sponsible for much of the daily and longer term variations seen in both the ionosphere and thermosphere. Although this has been appreciated for decades, there are still two critical questions for advancing our ability to model and predict the ionosphere-thermosphere (I-T) system: 1 Is the thermosphere-ionosphere \\

Richard Eastes; Stanley Solomon; Douglas Strickland

2010-01-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

267

Measurements of thermospheric molecular oxygen from the Solar Ultraviolet Spectral Irradiance Monitor  

NASA Astrophysics Data System (ADS)

We present a new data set of thermospheric O2 density profiles retrieved from solar occultation measurements made by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) instrument on board the UARS satellite. SUSIM is nominally a solar experiment whose mission was to measure the magnitude and variability of the UV solar irradiance. However, it was also capable of remotely sensing the Earth's upper atmosphere using occultation. SUSIM measurements of solar attenuation in the O2 Schumann Runge continuum are used to retrieve O2 density profiles between 110 and 240 km. Between October 1991 and February 2005, SUSIM performed solar occultation measurements up to one day per week, measuring full-disk solar extinction as a function of tangent altitude at three nominal wavelengths (144, 161 and 171 nm). These data have been inverted using an optimal estimation algorithm to produce altitude profiles of O2 density. This unique data set comprises approximately 1550 measurements, which span a wide range of solar and geomagnetic activity and latitudes up to 75° in each hemisphere. We present a discussion of the SUSIM instrument, the measurement technique employed for occultations, and the operational retrieval algorithm. A full error analysis and retrieval characterization study demonstrates that the SUSIM retrievals have uncertainties of 10-15% and a vertical resolution of 5-15 km, depending on altitude and measurement wavelength. The data thus have sufficient accuracy and resolution to provide scientifically useful constraints on the O2 abundance and variability, and initial comparisons show good overall agreement between the NRLMSIS-00 model and the SUSIM measurements.

Lumpe, J. D.; Floyd, L. E.; Herring, L. C.; Gibson, S. T.; Lewis, B. R.

2007-08-01

268

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

NASA Astrophysics Data System (ADS)

The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments.

Ermolli, I.; Matthes, K.; Dudok de Wit, T.; Krivova, N. A.; Tourpali, K.; Weber, M.; Unruh, Y. C.; Gray, L.; Langematz, U.; Pilewskie, P.; Rozanov, E.; Schmutz, W.; Shapiro, A.; Solanki, S. K.; Woods, T. N.

2013-04-01

269

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

NASA Astrophysics Data System (ADS)

The present study constitutes the generation and validation of the first satellite-based, long-term record of surface solar irradiance over the global oceans. The record is generated using Nimbus-7 earth radiation budget (ERB) wide-field-of-view (WFOV) planetary-albedo data as input to a numerical algorithm designed and implemented for this study based on radiative transfer theory. Net surface solar irradiance is obtained by subtracting the solar radiation reflected by the ocean-atmosphere system (measured by satellite) and the solar radiation absorbed by atmospheric constituents (modeled theoretically) from the solar irradiance at the top of the atmosphere (a known quantity). The resulting monthly mean values are computed on a 9° latitude-longitude spatial grid for November 1978°October 1985.Because direct measurements of surface solar irradiance are not available on the global spatial scales needed to validate the new approach, the ERB-based values cannot be verified directly against in situ pyranometer data. Although the ERB-based annual and monthly mean climatologies are compared with those obtained from ship observations and empirical formulas, a comparison with long-term mean climatologies does not provide an assessment of the month-to-month accuracies achieved using the new technique. Furthermore, the accuracy of the ship-based climatologies is questionable.Therefore, the new dataset is validated in comparisons with short-term, regional, high-resolution, satellite- based records (which were generated using methods that in turn have been validated using in situ measurements). The ERB-based values of net surface solar irradiance are compared with corresponding values based on radiance measurements taken by the VISSR (Visible-Infrared Spin Scan Radiometer) aboard GOES (Geostationary Operational Environmental Satellite) series satellites during the TOGA (Tropical Ocean Global Atmosphere), Tropic Heat, and MONEX (Monsoon Experiment) field experiments. The rms differences are 14.5 W m2 (i.e., 6.2% of the average VISSR-based value on monthly time scales) for the TOGA data comparison, 6.4 W m2 (i.e., 2.5% of the average VISSR-based value on monthly time scales) for the Tropic Heat data comparison, and 16.8 W m2 (i.e., 7.5% of the average VISSR-based value on monthly time scales) for the MONEX data comparison. The ERB-based record is also compared with an additional satellite-based dataset, focused primarily over the Atlantic Ocean, that was generated using radiance measurements from the Meteosat radiometer. On the basis of these validation studies, errors in the new dataset are estimated to lie between 10 and 20 W m2 on monthly time scales.

Chertock, Beth; Frouin, Robert; Gautier, Catherine

1992-09-01

270

Extraterrestrials  

NSDL National Science Digital Library

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

271

Short-term relationship between solar irradiances and equatorial peak electron densities  

NASA Astrophysics Data System (ADS)

The short-term relationship of the equatorial peak electron density and the solar short-wavelength irradiance is examined using foF2 observations from Jicamarca, Peru and recent solar irradiance measurements from satellites. Solar soft X-ray measurements from both the Student Nitric Oxide Explorer (SNOE) (1998-2000) and Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) (2002-2004) satellites as well as extreme ultraviolet (EUV) measurements from the TIMED satellite are used. Soft X-rays show similar or higher correlation with foF2 at short timescales (27 days or less) than EUV does, although the EUV correlation is higher for longer periods. For the short-term variations, both SNOE and TIMED observations have a higher correlation in the morning (˜0.46) than in the afternoon (˜0.1). In the afternoon, SNOE observations have a higher correlation (˜0.2) with foF2 than the TIMED observations (˜0.1 correlation), which may be due to differences in the solar cycle. At morning times, foF2 has a ˜27-day variation, consistent with the solar rotation rate. After noon, but not in the morning, a ˜13.5-day variation consistently appears in foF2. This ˜13.5-day variation is attributed to geomagnetic influences.

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

2007-06-01

272

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

273

Accurate monitoring of terrestrial aerosols and total solar irradiance: the NASA Glory mission  

NASA Astrophysics Data System (ADS)

Current uncertainties in the total solar irradiance (TSI) and aerosol radiative forcings of climate are so large that they limit quantitative evaluation of climate models against global temperature change. Reducing these uncertainties is the objective of the NASA Glory mission scheduled for launch in November 2010 as part of the NASA A-Train. Glory is intended to meet the following scientific objectives: Improve the quantification of solar variability by continuing the uninterrupted 32-year satellite measurement record of TSI, facilitate the quantification of the aerosol direct and indirect forcings of climate, and provide better aerosol representations for use by other operational satellite instruments.

Cairns, Brian; Mishchenko, Michael; Maring, Hal; Fafaul, Bryan; Pszcolka, Steve

2010-10-01

274

The Development of a New Model of Solar EUV Irradiance Variability  

NASA Astrophysics Data System (ADS)

The goal of this research project is the development of a new model of solar EUV (Extreme Ultraviolet) irradiance variability. The model is based on combining differential emission measure distributions derived from spatially and spectrally resolved observations of active regions, coronal holes, and the quiet Sun with full-disk solar images. An initial version of this model was developed with earlier funding from NASA. The new version of the model developed with this research grant will incorporate observations from SoHO as well as updated compilations of atomic data. These improvements will make the model calculations much more accurate.

Warren, Harry

2002-04-01

275

Intercomparison of spectroradiometers for solar spectral irradiance measurements preliminary results  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

276

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.

277

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.

278

Intra-hour Direct Normal Irradiance Solar Forecasting Using Genetic Programming  

NASA Astrophysics Data System (ADS)

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

Queener, Benjamin Daniel

279

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

Microsoft Academic Search

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

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

2002-01-01

280

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

Microsoft Academic Search

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

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

1999-01-01

281

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

282

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

Microsoft Academic Search

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

R. C. Willson

2008-01-01

283

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

Microsoft Academic Search

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

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

1993-01-01

284

Atrazine Degradation in Solar Irradiation\\/S-Doped Titanium Dioxide Treatment  

Microsoft Academic Search

Atrazine is a widely-used herbicide and always contaminates water bodies due to its relatively higher solubility and persistence. The removal efficiency of atrazine in water and the influencing factors by combined process of solar irradiation and S- doped TiO2 were studied in detail, in which S-doped TiO2 photo-catalyst with high sunlight activity was prepared by acid catalyzed hydrolysis method using

Cheng Liu; Wei Chen; Yu Sheng; Lei Li

2009-01-01

285

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

Microsoft Academic Search

Solar UV irradiance is measured in Westerland, Germany (54.9 degree(s) N, 8.3 degree(s) E) in the immediate vicinity of the North Sea shoreline. Measurements have been done since July 1993, focussing on the biologically effective UV radiation and the human body geometry. A grid double monochromator radiometer (DM 150, Bentham Instruments Comp., Reading, England) is used to measure the spectral

Carsten Stick; Volker Harms; Liane Pielke

1994-01-01

286

The Ecological Complex in Extraterrestrial Bases.  

National Technical Information Service (NTIS)

Several desirable requirements for life-support systems in extra-terrestrial bases are discussed: high reliability, minimum weight transported from Earth, ease of installation and maintenance, effective conversion of metabolic waste products, and maximum ...

S. H. Dole

1964-01-01

287

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

288

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

289

Effects of assumed solar spectral irradiance on intercomparisons of Earth-observing sensors  

NASA Astrophysics Data System (ADS)

Recent work by the Remote Sensing Group at the University of Arizona has focused on the calibration and radiance validation of numerous sensors that are part of NASA's Earth Observation System and Earth Sciences Enterprise. The unique orbital combination of many of these sensors, both from formation flying as well as from multi-sensor platforms, provides an unprecedented opportunity with which to cross- compare results from these sensors. This work presents the results of cross-comparisons between the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Moderate Resolution Imaging Spectroradiometer (MODIS), the Enhanced Thematic Mapper Plus (ETM+) sensor, the MODIS- ASTER Simulator (MASTER), and the Advanced Land Imager (ALI). Differences in the cross-comparison between these sensors can be attributed to numerous causes, including spatial registration effects, spectral differences in the sensors, and temporal changes in the atmosphere and surface between sensor collections. One aspect of cross-comparison studies that is often overlooked is the solar spectral irradiance that is used by each sensor's calibration and validation teams, and with the advent of onboard diffusers the selection of the solar irradiance values becomes even more critical. This work describes the differences between typical solar irradiance spectra that are being used for the above-listed sensors and the effect of these spectra on the intercomparison of at-sensor radiances from earth-observing sensors.

Thome, Kurtis J.; Biggar, Stuart F.; Slater, Philip N.

2001-12-01

290

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

291

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

292

Ion irradiation induced effects on airless bodies in the Solar System  

NASA Astrophysics Data System (ADS)

Irradiation by cosmic ions plays a relevant role in the "space weathering" of solid materials in the airless bodies (rocky and/or icy objects) in the Solar System. Here, I discuss about some of the effects that have been studied in "simulation" experiments with a view to their astrophysical relevance. In particular I review some experimental results obtained so far after irradiation of relevant materials, namely: sputtering, ion implantation, and chemical synthesis of molecular species different from the original ones. All of those effects are accomplished by changes in the optical properties of irradiated layers and then of the color of the surfaces of the airless bodies. Some specific examples of the application of the experimental results to the physics and chemistry of planetary surfaces are discussed as well.

Strazzulla, G.

2012-02-01

293

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

2013-08-30

294

Clouds, solar irradiance and mean surface temperature over the last century  

NASA Astrophysics Data System (ADS)

The inter-relation of clouds, solar irradiance and surface temperature is complex and subject to different interpretations. Here, we continue our recent work, which related mainly to the period from 1960 to the present, back to 1900 with further, but less detailed, analysis of the last 1000 years. The last 20 years is examined especially. Attention is given to the mean surface temperature, solar irradiance correlation, which appears to be present (with decadal smoothing) with a 22-year period; it is stronger than the 11-year cycle correlation with one year resolution. UV in the solar radiation is a likely cause. Cloud data are taken from synoptic observations back to 1952 and, again, there appears to be a correlation--with opposite phase for high and low clouds--at the 20-30 y level. Particular attention is devoted to answering the question, [`]what fraction of the observed increase in mean Global temperature () can be attributed to solar, as distinct from man-made, effects?' We conclude that a best estimate is [`]essentially' all from 1900 to 1956 and <14% from 1956 to the present.

Erlykin, A. D.; Sloan, T.; Wolfendale, A. W.

2010-04-01

295

Solar irradiances and radiances of UV and EUV lines during the minimum of sunspot activity in 1996  

Microsoft Academic Search

Full Sun observations in UV and EUV emission lines were performed by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric pre-flight calibration of SUMER is traceable to a primary radiometric source standard - the electron storage ring BESSY. Based on this calibration, the irradiance values at SOHO and at 1 AU

K. Wilhelm; P. Lemaire; I. E. Dammasch; J. Hollandt; U. Schuehle; W. Curdt; T. Kucera; D. M. Hassler; M. C. E. Huber

1998-01-01

296

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

Microsoft Academic Search

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

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

1997-01-01

297

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

NASA Astrophysics Data System (ADS)

During periods of high solar activity, the Earth receives ? 0.1% higher total solar irradiance (TSI) than during low activity periods. Variations of the solar spectral irradiance (SSI) however, can be larger, with relative changes of 1 to 20% observed in the ultraviolet (UV) band, and in excess of 100% in the soft X-ray range. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. Lack of long and reliable time series of SSI measurements makes the accurate quantification of solar contributions to recent climate change difficult. In particular, the most recent SSI measurements show a larger variability in the UV spectral range and anomalous changes in the visible and near-infrared (NIR) bands with respect to those from earlier observations and from models. A number of recent studies based on chemistry-climate model (CCM) simulations discuss the effects and implications of these new SSI measurements on the Earth's atmosphere, which may depart from current expectations. This paper summarises our current knowledge of SSI variability and its impact on Earth's climate. An interdisciplinary analysis of the topic is given. New comparisons and discussions are presented on the SSI measurements and models available to date, and on the response of the Earth's atmosphere and climate to SSI changes in CCM simulations. In particular, the solar induced differences in atmospheric radiative heating, temperature, ozone, mean zonal winds, and surface signals are investigated in recent simulations using atmospheric models forced with the current lower and upper boundaries of SSI solar cycle estimated variations from the NRLSSI model data and from SORCE/SIM measurements, respectively. Additionally, the reliability of available data is discussed and additional coordinated CCM experiments are proposed.

Ermolli, I.; Matthes, K.; Dudok de Wit, T.; Krivova, N. A.; Tourpali, K.; Weber, M.; Unruh, Y. C.; Gray, L.; Langematz, U.; Pilewskie, P.; Rozanov, E.; Schmutz, W.; Shapiro, A.; Solanki, S. K.; Thuillier, G.; Woods, T. N.

2012-09-01

298

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

Microsoft Academic Search

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

Volker Quaschning

2004-01-01

299

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

300

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

301

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

NASA Astrophysics Data System (ADS)

The spectral irradiance at the center of the solar H I Lyman ? ( ?=121.5664nm, referred to as Ly? in this paper) line profile is the main excitation source responsible for the atomic hydrogen resonant scattering of cool material in our Solar System. It has therefore to be known with the best possible accuracy in order to model the various Ly? emissions taking place in planetary, cometary, and interplanetary environments. Since the only permanently monitored solar irradiance is the total one (i.e. integrated over the whole Ly? line profile), Vidal-Madjar [1975. Evolution of the solar Lyman alpha flux during four consecutive years. Solar Phys. 40, 69-86] using Orbiting Solar Observatory 5 (OSO-5) satellite Ly? data, established a semi-empirical formula allowing him to deduce the central spectral Ly? irradiance from the total one. This relation has been extensively used for three decades. But, at the low altitude of the OSO-5 orbit, the central part of the solar line profile was deeply absorbed by a large column of exospheric atomic hydrogen. Consequently, the spectral irradiance at the center of the line was obtained by a complex procedure confronting the observations with simulations of both the geocoronal absorption and the self-reversed shape of the solar Ly? profile. The SUMER spectrometer onboard SOHO positioned well outside the hydrogen geocorona, provided full-Sun Ly? profiles, not affected by such an absorption [Lemaire et al., 1998. Solar H I Lyman ? full disk profile obtained with the SUMER/SOHO spectrometer. Astron. Astrophys. 334, 1095-1098; 2002. Variation of the full Sun Hydrogen Lyman ? and ? profiles with the activity cycle. Proc. SOHO 11 Symposium, ESA SP-508, 219-222; 2004. Variation of the full Sun Hydrogen Lyman profiles through solar cycle 23. COSPAR 2004 Meeting], making it—for the first time—possible to measure the spectral and total Ly? solar irradiances directly and simultaneously. A new relation between these two quantities is derived in an expression that is formally similar to the previous one, but with significantly different parameters. After having discussed the potential causes for such differences, it is suggested that the new relation should replace the old one for any future modeling of the numerous Ly? absorptions and emissions observed in the Solar System.

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

2005-11-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

303

Climate response to changes in atmospheric carbon dioxide and solar irradiance on the time scale of days to weeks  

NASA Astrophysics Data System (ADS)

Recent studies show that fast climate response on time scales of less than a month can have important implications for long-term climate change. In this study, we investigate climate response on the time scale of days to weeks to a step-function quadrupling of atmospheric CO2 and contrast this with the response to a 4% increase in solar irradiance. Our simulations show that significant climate effects occur within days of a stepwise increase in both atmospheric CO2 content and solar irradiance. Over ocean, increased atmospheric CO2 warms the lower troposphere more than the surface, increasing atmospheric stability, moistening the boundary layer, and suppressing evaporation and precipitation. In contrast, over ocean, increased solar irradiance warms the lower troposphere to a much lesser extent, causing a much smaller change in evaporation and precipitation. Over land, both increased CO2 and increased solar irradiance cause rapid surface warming that tends to increase both evaporation and precipitation. However, the physiological effect of increased atmospheric CO2 on plant stomata reduces plant transpiration, drying the boundary layer and decreasing precipitation. This effect does not occur with increased solar irradiance. Therefore, differences in climatic effects from CO2 versus solar forcing are manifested within days after the forcing is imposed.

Cao, Long; Bala, Govindasamy; Caldeira, Ken

2012-09-01

304

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

NASA Astrophysics Data System (ADS)

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.

1989-07-01

305

Optimal design of irradiance redistribution guides for the National Renewable Energy Laboratory's high-flux solar furnace  

NASA Astrophysics Data System (ADS)

The National Renewable Energy Laboratory (NREL) has developed and operates the high-flux solar furnace (HFSF), a 10-kW solar concentrator used for research in solar energy applications. An application of ongoing interest is the heat-bonding of metallic foils to ceramic substrates, a process requiring a highly uniform irradiance distribution over a 10 by 10-cm target area, as well as a mean irradiance of at least 10 W/cm2, and a working distance of at least 10-cm from the optics. Science Applications International Corporation (SAIC) and NREL have developed designs for two reflective irradiance redistribtuion guides (IRGs) for use in conjunction with the HFSF, which provide significantly enhanced irradiance uniformity while exceeding the mean-irradiance and working-distance requirements. Irradiance- uniformity levels of 7.2% and 3.1% root-mean-square (RMS) deviation over the target area were achieved by the two IRG designs. The designs were generated using SAICs nonimaging concentrator synthesis code, which employs a global optimization procedure. The HFSF was modeled by means of an optical ray set produced by NREL's solar furnace code. The IRG designs are novel in that they feature re-entrant optics combined with the intentional use of ray paths having different nubmers of multiple reflections within a single reflective optical component in order to achieve the desired irradiance distribution.

Bortz, John C.; Shatz, Narkis E.; Lewandowski, Allan

1995-08-01

306

Are the most recent estimates for Maunder Minimum solar irradiance in agreement with temperature reconstructions?  

NASA Astrophysics Data System (ADS)

Estimates for the total solar irradiance (TSI) during the 17th-century Maunder Minimum published in the last few years have pointed towards a TSI difference of 0.2-0.7 W m-2 as compared to the 2008/2009 solar minimum. Two recent studies, however, give anomalies which differ from this emerging consensus. The first study indicates an even smaller TSI difference, placing the Maunder Minimum TSI on the same level as the 2008/2009 minimum. The second study on the other hand suggests a very large TSI difference of 5.8 W m-2. Here I use coupled climate simulations to assess the implications of these two estimates on Northern-hemisphere surface air temperatures over the past millennium. Using a solar forcing corresponding to the estimate of the first study, simulated Northern-hemisphere temperatures over the past millennium are consistent with reconstructed surface air temperatures. The large TSI differences between times of high and low solar activity as suggested by the second study, however, yield temperatures during all past grand solar minima that are too low, an excessive variance in Northern-hemisphere temperature on timescales of 50-100 years as compared to reconstructions, and temperatures during the first half of the 20th century which are too low and inconsistent with the instrumental temperature record. In summary this suggests a more moderate TSI difference of less than 1 W m-2 and possibly as low as 0-0.3 W m-2.

Feulner, Georg

2011-08-01

307

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

308

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

2013-09-01

309

Total Solar Irradiance: What Have We Learned from the Last Three Cycles and the Recent Minimum?  

NASA Astrophysics Data System (ADS)

The record of total solar irradiance (TSI) during the past 35 years shows similarities of the three solar cycles, but also important differences. During the recent minimum with an unusually long periods with no sunspots, TSI was also extremely low, namely 25% of a typical cycle amplitude lower than in 1996. Together with the values during the previous minima this points to a long-term change related to the strength of solar activity. On the other hand, activity indices as the 10.7 cm radio flux (F10.7), the CaII and MgII indices and also the Ly- ? irradiance, show a much smaller decrease. This means that proxy models for TSI based on the photometric sunspot index (PSI), and on e.g. MgII index to represent faculae and network have to be complemented by a further component for the long-term change. TSI values at minima are correlated with the simultaneous values of the open magnetic field of the Sun at 1 AU and thus, these values may be used as a surrogate for the long-term change component. Such a 4-component model explains almost 85% of the variance of TSI over the three solar cycles available. This result supports also the idea that the long-term change of TSI is not due to manifestations of surface magnetism as the solar cycle modulation, but due to a change of the global temperature of Sun modulated by the strength of activity—being lower during low activity. To explain the difference between the minima in 1996 and 2008 we need a change of only 0.25 K.

Fröhlich, Claus

2013-06-01

310

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

PubMed

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

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

2008-04-01

311

Influence of high levels of cloud cover on vitamin D effective and erythemal solar UV irradiances.  

PubMed

The solar irradiances for the initiation of vitamin D synthesis (UV(D3)) have been measured concurrently with the amount of cloud cover to investigate the influence of high cloud cover fraction. The cases of 6.5 and more octa cloud cover were considered for five solar zenith angle (SZA) ranges up to 80°. For each of the SZA ranges, the UV(D3) reduced due to the high cloud cover. The average of the ratios of the UV(D3) irradiances on a cloudy day to those on a clear day with the corresponding ozone and SZA are 0.71 for the 6.5-7.5 octa cloud and 0.45 for the more than 7.5 octa cloud ranges. The exposure times necessary to receive 1/3 MED to a horizontal plane were found to increase as the amount of cloud cover increased. For each cloud cover category, the range of values increased with cloud cover and with SZA. This research shows that the current public recommendations on the times of solar UV exposures required to produce adequate vitamin D are inappropriate for situations of more than 6.5 octa cloud. PMID:23108371

Parisi, Alfio V; Turnbull, David J; Downs, Nathan J

2012-12-01

312

How to build a new composite of the total solar irradiance out of disparate observations ?  

NASA Astrophysics Data System (ADS)

Several attempts have been made to merge all total solar irradiance (TSI) observations into a single composite, which is crucial for assessing the presence of long-term trends in the solar radiative output. There exist presently three composites, which are based on different assumptions on the data, and also exhibit differing trends. This problem of merging different and disparate observations of the same quantity occurs in various contexts, for example in the making of a composite MgII index. The Bayesian framework is ideally suited for this because it precisely allows to build a TSI composite that is consistent with all the observations, given their uncertainties. This approach has been successfully used for climate records, but apparently never for solar or for geomagnetic proxies. We show how to build a new composite of the TSI, by using a multiscale method that reconstructs the TSI separately for different time scales. We then compare this new composite to existing ones and to results from spectral irradiance models.

Dudok de Wit, Thierry; Fröhlich, Claus

2013-04-01

313

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

NASA Astrophysics Data System (ADS)

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

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

1995-09-01

314

Far-side imaging tools, front-side imaging, and EUV solar irradiance forecasting  

NASA Astrophysics Data System (ADS)

Currently we are in an advanced stage of the development of an application of both far-side and front-side imaging to EUV solar irradiance forecast. The basic method and its application to one case were described by Fontenla et al. (2009). This method uses a combination of several techniques for far-side imaging with front-side images at various wavelengths, and EUV spectral synthesis. This presentation shows that all these techniques should be used in concert to produce a reasonably accurate EUV irradiance forecast at Earth and other planets. The combination of SOHO/SWAN Ly alpha backscattering, far-side helioseismic images, and front-side imaging resolves the weaknesses of each technique by itself. In particular, the presentation will show how the SOHO/SWAN data plays a very important role in this combination by supplying unique EUV data (Ly alpha) that is not directly inferred by helioseismic methods. The SOHO/SWAN data plays a key role in the combination by allowing us to infer the evolution in EUV brightness of the active regions on the far-side of the Sun. However, because this method does not provide a good localization of the emission sources in the Sun, it needs to me complemented by the good localization that helioseismology provides. Because the Ly alpha backscattering is sensitive to active network and plage these images provide essential information for determining the far-side evolution of components to the solar flux that are not detected by helioseismology but have important effects on the EUV irradiance. However, again because of the poor localization of these features in backscattering images, front side imaging is also a necessary complement that helps in the localization on the solar surface of the changes observed in the SOHO/SWAN images.

Fontenla, J. M.; Quemerais, E.; Lindsey, C. A.

2011-12-01

315

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

316

Developments, characterization and proton irradiation damage tests of AlN detectors for VUV solar observations  

NASA Astrophysics Data System (ADS)

For next generation spaceborne solar ultraviolet radiometers, innovative metal–semiconductor–metal detectors based on wurtzite aluminum nitride are being developed and characterized. A set of measurement campaigns and proton irradiation damage tests was carried out to obtain their ultraviolet-to-visible characterization and degradation mechanisms. First results on large area prototypes up to 4.3 mm diameter are presented here. In the wavelength range of interest, this detector is reasonably sensitive and stable under brief irradiation with a negligible low dark current (3–6 pA/cm2). No significant degradation of the detector performance was observed after exposure to protons of 14.4 MeV energy, showing a good radiation tolerance up to fluences of 1 × 1011 protons/cm2.

BenMoussa, A.; Soltani, A.; Gerbedoen, J.-C.; Saito, T.; Averin, S.; Gissot, S.; Giordanengo, B.; Berger, G.; Kroth, U.; De Jaeger, J.-C.; Gottwald, A.

2013-10-01

317

A survey of diffraction effects in various total solar irradiance monitors  

NASA Astrophysics Data System (ADS)

Instruments that monitor total solar irradiance (TSI) need to be fully characterized in regards to many aspects. Important effects include proper realization of the optical watt, accurate determination of the effective area of the detector, minimization and characterization of light scatter, and correcting for diffraction effects that undermine geometrical-optics assumption. We will discuss trends in diffraction effects for the various present and past TSI instruments. Our discussion will include estimates of the effects on results because of the finite size of the sun as well as its limb darkening. Our survey will include analysis of many US and European satellite-based sensors.

Shirley, E. L.; Therniesen, A.; Gong, Q.

2010-12-01

318

Formation of solar absorber surface on nickel with femtosecond laser irradiation  

NASA Astrophysics Data System (ADS)

Through femtosecond (fs) laser pulse irradiation, we produce two-dimensional quasiperiodic arrays of nanostructure-covered conical microstructures (NC-CMs) on Ni. We also find that a significant amount of nickel oxide covers NC-CMs owing to the interaction of fs laser pulses with Ni in ambient air. We show that, by controlling the fluence of laser, the reflectance of the fs laser-treated Ni surface can change dramatically in the infrared but the surface still has a high absorptance at UV and visible wavelengths. Because of this unique spectral reflectance, the fs laser-treated Ni surface is well suited for use as a solar absorber surface.

Hwang, Taek Yong; Vorobyev, A. Y.; Guo, Chunlei

2012-08-01

319

Measurements of Solar Irradiance from a High-Density Radiometer Network  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

320

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

321

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

SciTech Connect

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. [Brookhaven National Lab., Upton, NY (United States); Michalsky, J.J. [State Univ. of New York, Albany, NY (United States); Anderson, G.P. [Hanscomb AFB (United States); Ferrare, R.A. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Ten Brink, H.M. [Energy Research Inst. (Netherlands)

1997-03-01

322

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

323

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

324

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...

325

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

SciTech Connect

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

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

2009-03-11

326

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); Benmansour, S. [U.S.T.H.B., El-Alia Bab-Ezzouar (Algeria)

1995-03-01

327

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

328

Using reduced data sets ISCCP-B2 from the Meteosat satellites to assess surface solar irradiance  

Microsoft Academic Search

This paper explores the capabilities of a combination of the reduced data set ISCCP-B2 from the Meteosat satellites and the recently developed method Heliosat-2 to assess the daily mean of the surface solar irradiance at any geographical site in Europe and Africa. Firstly, we discuss the implementation of the method Heliosat-2. Secondly, B2-derived irradiances are compared to coincident measurements made

M. Lefèvre; L. Wald; L. Diabaté

2007-01-01

329

Long-term trends in solar irradiance in Ireland and their potential effects on gross primary productivity  

Microsoft Academic Search

Long-term trends in total solar irradiance (Rs), diffuse irradiance (Rd) and pan evaporation (Epan), from various sites in Ireland, were examined over the last 20–50 years. This information was used to estimate the impact of changes in Rs and Rd on gross primary productivity (GPP) of forest, arable and grassland ecosystems. Analysis of the data indicated a significant (P<0.0001) reduction

Kevin Black; Phill Davis; Peter Lynch; Mike Jones; Michael McGettigan; Bruce Osborne

2006-01-01

330

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

NASA Astrophysics Data System (ADS)

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

Scafetta, N.

2008-12-01

331

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.

332

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.

333

HUMAN UTILIZATION OF SUBSURFACE EXTRATERRESTRIAL ENVIRONMENTS  

Microsoft Academic Search

Caves have been used in the ancient past as shelter or habitat by many organisms (including humans). Since antiquity, humans have explored caves for the minerals they contain and sometimes for ceremonial purposes. Over the past century, caves have become the target of increasing exploration, scientific research, and recreation. The use of caves on extraterrestrial bodies for human habitation has

P. J. Boston; R. D. Frederick; S. M. Welch; J. Werker; T. R. Meyer; B. Sprungman

334

Exponential evolution - Implications for intelligent extraterrestrial life  

Microsoft Academic Search

The implications for intelligent extraterrestrial life are investigated for some measures of biologic complexity, including maximal levels of brain development, which are exponential functions of time through intervals of 10 to the 6th to the 9th years. Trends in brain evolution are shown to indicate that other organisms could attain human levels within approximately 10 to the 7th years. The

D. A. Russell

1983-01-01

335

The probability of contact with extraterrestrial life  

Microsoft Academic Search

The paper attempts to explain why technologically advanced extraterrestrial civilizations have not been detected. The discussion is restricted to living matter dependent on macromolecules with carbon-carbon chains and the probability of finding a physical environment similar to the terrestrial one. Drake's (1961) equation for the probable number of technological civilizations in a galaxy is reformulated so that the fractions of

N. H. Langton

1976-01-01

336

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

337

EFFECTS OF EXTRATERRESTRIAL HYDROTHERMAL PROCESSES IN CHONDRITES  

Microsoft Academic Search

Hydrothermal reactions in terrestrial geological processes may be defined in a simplified form as those that cause numerous alterations of earlier formed rocks and minerals due to the action of hot aqueous solutions, usually in a postmagmatic stage. Under extraterrestrial conditions hydrothermal processes should occur probably less often because of the lack of the environments rich in such solutions. Only

Andrzej MANECK

338

Conway Morris: Extraterrestrials: Aliens like us?  

NASA Astrophysics Data System (ADS)

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

Morris, Simon Conway

2005-08-01

339

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

340

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

341

Analysis of terrestrial solar radiation exergy  

Microsoft Academic Search

Based on Candau’s definition of radiative exergy, the exergy of the extraterrestrial and the terrestrial solar radiation are computed and compared by using the solar spectral radiation databank developed by Gueymard. The results show that within the spectrum region from 0.28 to 4.0 ?m, the total energy quality factor (i.e., the exergy-to-energy ratio) of extraterrestrial solar radiation is about 0.9292,

S. X. Chu; L. H. Liu

2009-01-01

342

Effects of water-filtered infrared A irradiation on human fibroblasts.  

PubMed

Infrared radiation is a substantial part of the solar energy output reaching the earth surface. Therefore, exposure of humans to infrared radiation is common. However, whether and how infrared (IR) or infrared A acts on human skin cells is still under debate. Recently the generation of reactive oxygen species by water-filtered infrared A (wIRA) irradiation was postulated. wIRA shows a spectral distribution similar to that of solar irradiation at the earth's surface. Thus, the need for protection of human skin from both solar- and artificially generated infrared A irradiation was concluded. Here we demonstrate that in human dermal fibroblasts this reactive oxygen species generation is dependent on heat formation by infrared A and can be reproduced by thermal exposure. On the other hand wIRA irradiation had no detectable effect if the temperature in the cells was kept constant, even if irradiance exceeded the extraterrestrial solar irradiance in the IR range by a factor of about 4 and the maximum at noontime in the tropics by a factor up to about 6. This could be demonstrated by the measurement of oxidant formation using H(2)DCFDA and the determination of protein carbonyls. In additional experiments we could show that during thermal exposure the mitochondria contribute significantly to oxidant production. Further experiments revealed that the major absorbance of infrared is due to absorption of the energy by cellular water. PMID:19853655

Jung, Tobias; Höhn, Annika; Piazena, Helmut; Grune, Tilman

2009-10-21

343

Solar EUV Monitor (SEM) absolute irradiance measurements and how they are affected by choice of reference spectrum  

NASA Astrophysics Data System (ADS)

The SOHO/CELIAS Solar EUV Monitor (SEM) has measured absolute extreme ultraviolet (EUV) solar irradiance nearly continuously over a 15 year period that includes two solar cycle minima, 22/23 (1996) and 23/24 (2008). Calibration of the SEM flight instrument and verification of the data have been maintained through measurements from a series of sounding rocket calibration underflights that have included a NIST calibrated SEM clone instrument as well as a Rare Gas Ionization Cell (RGIC) absolute detector. From the beginning of SEM data collection in 1996, the SOLERS 22 fixed reference solar spectrum has been used to calculate absolute EUV flux values from SEM raw data. Specifically, the reference spectrum provides a set of weighting factors for determining a weighted average for the wavelength dependent SEM response. The spectrum is used for calculation of the second order contamination in the first order channel signals, and for the comparison between SEM flux measurements with broader-band absolute RGIC measurements. SOHO/SEM EUV flux measurements for different levels of solar activity will be presented to show how the choice of reference spectra now available affects these SEM data. Both fixed (i.e. SOLERS 22) and non-fixed (Solar Irradiance Platform/Solar 2000 and SDO/EVE/MEGS) reference spectra have been included in this analysis.

Wieman, Seth R.; Judge, Darrell L.; Didkovsky, Leonid V.

2011-09-01

344

Comparison of model estimated and measured direct-normal solar irradiance  

SciTech Connect

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

Halthore, R.N.; Schwartz, S.E. [Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States); Michalsky, J.J. [Atmospheric Sciences Research Center, State University of New York at Albany (United States); Anderson, G.P. [Phillips Laboratory/Geophysics Directorate, Hanscom Air Force Base, Massachusetts (United States); Ferrare, R.A. [Hughes STX Corporation, Lanham, Maryland (United States); Holben, B.N. [NASA Goddard Space Flight Center, Greenbelt, Maryland (United States); Ten Brink, H.M. [Netherlands Energy Research Foundation, ECN, Petten (Netherlands)

1997-12-01

345

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

2011-10-28

346

A COMPARISON OF THREE MODELS FOR ESTIMATION OF GLOBAL SOLAR IRRADIATION ON TILTED AND ORIENTED SURFACES IN ATHENS  

Microsoft Academic Search

Solar radiation data from one location in Greece (Athens), are used to test the applicability of three models for computing global irradiance on tilted surfaces. The models selected for discussion, applicability, and comparisons are the model suggested by Liu and Jordan dated 1962, the model of Klein dated 1977, and the model of Klein and Theilacker dated 1981. All these

B. M. SYNODINOU; BASIL D. KATSOULIS

1996-01-01

347

Modeling Total Solar Irradiance with San Fernando Observatory Ground-Based Photometry: Comparison with ACRIM, PMOD, and RMIB Composites  

NASA Astrophysics Data System (ADS)

We model total solar irradiance (TSI) using photometric irradiance indices from the San Fernando Observatory (SFO), and compare our model with measurements compiled from different space-based radiometers. Space-based measurements of TSI have been obtained recently from ACRIM-3 on board the ACRIMSAT. These data have been combined with other data sets to create an ACRIM-based composite. From VIRGO on board the Solar and Heliospheric Observatory (SOHO) spacecraft two different TSI composites have been developed. The VIRGO irradiance data have been combined by the Davos group to create a composite often referred to as PMOD (Physikalisch-Meteorologisches Observatorium Davos). Also using data from VIRGO, the Royal Meteorological Institute of Belgium (RMIB) has created a separate composite TSI referred to here as the RMIB composite. We also report on comparisons with TSI data from the Total Irradiance Monitor (TIM) experiment on board the Solar Radiation and Climate Experiment (SORCE) spacecraft. The SFO model correlates well with all four experiments during the seven-year SORCE interval. For this interval, the squared correlation coefficient R 2 was 0.949 for SORCE, 0.887 for ACRIM, 0.922 for PMOD, and 0.924 for RMIB. Long-term differences between the PMOD, ACRIM, and RMIB composites become apparent when we examine a 21.5-year interval. We demonstrate that ground-based photometry, by accurately removing TSI variations caused by solar activity, is useful for understanding the differences that exist between TSI measurements from different spacecraft experiments.

Chapman, G. A.; Cookson, A. M.; Preminger, D. G.

2013-04-01

348

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...

349

Solar irradiation of the seed germination stimulant karrikinolide produces two novel head-to-head cage dimers.  

PubMed

Karrikinolide is a naturally derived potent seed germination stimulant that is responsible for triggering the germination of numerous plant species from various habitats around the world. We now report that solar irradiation of karrikinolide yields two novel head-to-head cage photodimers with the formation, stability and bioactivity of both presented herein. PMID:22514031

Scaffidi, Adrian; Waters, Mark T; Skelton, Brian W; Bond, Charles S; Sobolev, Alexandre N; Bythell-Douglas, Rohan; McKinley, Allan J; Dixon, Kingsley W; Ghisalberti, Emilio L; Smith, Steven M; Flematti, Gavin R

2012-04-19

350

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

2012-03-29

351

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

NASA Astrophysics Data System (ADS)

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

Kärner, Olavi

2009-06-01

352

An Instrument-Based Method to Search for Extraterrestrial Interstellar Robotic Probes  

NASA Astrophysics Data System (ADS)

Technological advancements have allowed us to build robotic space probes to remotely explore the solar system. Interstellar robotic missions are under serious consideration. Advanced extant extraterrestrial civiliza- tions within the galaxy, if they exist, are very likely exploring with robotic probes as well, some of which may have reached our solar system and taken an interest in life on Earth. Recent technological advances make it possible to conduct a scientific search for evidence of extraterrestrial interstellar robotic probes. Modern solid-state sensing devices and scientific instruments, combined with high-speed computer hardware, can be used in an effort to detect the physical presence of a probe. The SETV (Search for Extraterrestrial Visitation) model is new and an offspring of SETA (artifacts) and SETI. SETV includes the construction of passive autonomous data acquisition platforms using “commercial off-the-shelf” hardware, to collect reliable and unambiguous data on anomalous observational phenomena that may be ETI probes. The SETV hypothesis and experimental methods will be described. The SETV hypothesis can be experimentally tested and attempts to statistically reject a null hypothesis which states that ETI probes do not exist. SETV Pre and Post-detection protocols are necessary and will be examined. SETV is a timely, results-oriented, method worthy of serious consideration in our continuing desire to answer the question “Are we alone?”.

Stride, S. L.

353

Validation of visible/near-IR atmospheric absorption and solar emission spectroscopic models at 1 cm-1 resolution  

NASA Astrophysics Data System (ADS)

A Fourier transform infrared (FTIR) spectrometer, operating at 1 cm-1 resolution between 9000 and 24,669 cm-1 (0.405-1.111 ?m) has been used to check the spectral composition of databases that form the basis for most atmospheric absorption parameterizations used in climate models, remote sensing, and other radiative transfer simulations. The spectrometer, operating near sea level under clear skies, obtained relative atmospheric transmission measurements of the direct solar beam by means of a heliostat. The spectroscopic data were compared with a line-by-line radiative transfer model (LBLRTM) calculation of direct solar beam flux, which used a input data a monochromatic model extraterrestrial solar flux spectrum currently in common use. This intercomparison revealed that the extraterrestrial solar flux spectrum contains 266 solar absorption features that do not appear in the data, resulting in an excess of approximately 1.92 W m-2 in the model's solar constant. The intercomparison also revealed 97 absorption features in the data that do not appear in the HITRAN-96 database as used by LBLRTM, resulting in a model underestimate of shortwave absorption of ˜0.23 W m-2 for a solar zenith angle of 42°. These small discrepancies revealed by the intercomparison indicate that current extraterrestrial solar irradiance models and spectroscopic databases used by shortwave atmospheric radiative transfer models are nearly entirely complete for purposes of atmospheric energy budget calculation. Thus clear or cloudy sky `excess absorption' is unlikely to be related to an incomplete identification of atmospheric absorbing gases and their spectroscopic features, at 1 cm-1 resolution, for a clean troposphere of normal composition.

Lubin, Dan; Vogelmann, Andrew; Lehr, Pamela J.; Kressin, Ann; Ehramjian, James; Ramanathan, V.

2000-09-01

354

The search for extra-terrestrial intelligence.  

PubMed

Modern history of the search for extra-terrestrial intelligence is reviewed. The history of radio searches is discussed, as well as the major advances that have occurred in radio searches and prospects for new instruments and search strategies. Recent recognition that searches for optical and infrared signals make sense, and the reasons for this are described, as well as the equipment and special detection methods used in optical searches. The long-range future of the search for extra-terrestrial intelligence (SETI) is discussed in the context of the history of rapid change, on the cosmic and even the human time scale, of the paradigms guiding SETI searches. This suggests that SETI searches be conducted with a very open mind. PMID:21220287

Drake, Frank

2011-02-13

355

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

356

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

357

Carbonaceous chondritic asteroids - The ideal extraterrestrial resource  

NASA Astrophysics Data System (ADS)

It is proposed that carbonaceous chondritic asteroids be used as extraterrestrial resources because they contain biogenic resources, water, hydrocarbons and water soluble metal salts. The chemical composition determined for carbonaceous chondritic asteroids is presented in tables and the processes for extracting iron ore and silicon, aluminum, magnesium, calcium, sulfur, and phosphorus compounds from them are examined. It is suggested that these asteroids could provide valuable resources for lunar and LEO colonies.

Kuck, David L.

358

Paleoindian demography and the extraterrestrial impact hypothesis  

Microsoft Academic Search

Recently it has been suggested that one or more large extraterrestrial (ET) objects struck northern North America 12,900 ± 100 calendar years before present (calBP) [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104: 16016-16021]. This impact is claimed to have triggered the Younger Dryas major cooling event and resulted in the extinction of the North American megafauna.

Briggs Buchanan; Mark Collard; Kevan Edinborough

2008-01-01

359

METI: Messaging to ExtraTerrestrial Intelligence  

NASA Astrophysics Data System (ADS)

Perhaps, after 50 years of listening to nothing but cosmic static, it is time to recognize that the time has come for humankind to take the lead in helping to end the Great Silence. Could it be that the future of SETI lies not in receiving, but rather in transmitting? In this chapter we introduce Messaging to Extra-Terrestrial Intelligence (METI) as a complementary science to SETI observations.

Zaitsev, Alexander L.

360

Paleoindian demography and the extraterrestrial impact hypothesis  

PubMed Central

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

Buchanan, Briggs; Collard, Mark; Edinborough, Kevan

2008-01-01

361

Advanced Curation of Current and Future Extraterrestrial Samples  

NASA Astrophysics Data System (ADS)

Advanced curation of current and future extraterrestrial samples includes: inorganic/organic contamination; preservation temperature; non-destructive examination; microscopic sample hangling/preservation; unopened lunar cores; informatics.

Allen, C. C.

2013-09-01

362

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

363

Estimation of global solar irradiation on horizontal and inclined surfaces based on the horizontal measurements  

Microsoft Academic Search

Solar radiation data are essential in the design of solar energy conversion devices. In this regard, empirical models were selected to estimate the global solar radiation on horizontal and inclined surfaces. The hourly solar radiation data measured at the study area during the period of 2004–2007, were used to calculate solar radiations using selected models. The selected models were compared

A. M. Muzathik; M. Z. Ibrahim; K. B. Samo; W. B. Wan Nik

2011-01-01

364

Solar Cycle Irradiance Variation Measured by TIMED\\/SEE and the Effect on Thermospheric Response  

Microsoft Academic Search

Measurements by the TIMED Solar EUV Experiment (SEE) are used to specify solar forcing during the declining phase of solar cycle 23 for computations by the NCAR Thermosphere- Ionosphere-Electrodynamic General Circulation Model (TIEGCM). The TIEGCM is run using SEE version 8 data, SEE version 9 data, and the EUVAC solar proxy model, as solar input. Results are compared with measurements

Liying Qian; Stanley Solomon; M. G. Mlynczak; Bruce R. Bowman

2008-01-01

365

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

366

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

367

Fear, pandemonium, equanimity and delight: human responses to extra-terrestrial life.  

PubMed

How will people respond to the discovery of extra-terrestrial life? Potentially useful resources for addressing this question include historical prototypes, disaster studies and survey research. Reactions will depend on the interplay of the characteristics of the newly found life, the unfolding of the discovery, the context and content of the message and human information processing as shaped by biology, culture and psychology. Pre-existing images of extra-terrestrials as god-like, demonic, or artificial will influence first impressions that may prove highly resistant to change. Most probably people will develop comprehensive images based on minimal information and assess extra-terrestrials in the same ways that they assess one another. Although it is easy to develop frightening scenarios, finding microbial life in our Solar System or intercepting a microwave transmission from many light years away are less likely to be met with adverse reactions such as fear and pandemonium than with positive reactions such as equanimity and delight. PMID:21220289

Harrison, Albert A

2011-02-13

368

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.

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

2010-01-01

369

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

PubMed

Exposure of normal human breast skin ex vivo to physiological levels of UV-B and solar simulated UV results in a UV dose- and time-dependent increase in epidermal p53, as determined by PAGE analysis. Peak p53 levels are detected 12 to 24 h post irradiation with UV-B (470-1410 mJ cm-2) and solar simulated UV (5-12 minimal erythema dose (MED) equivalents). Irradiation with an FS20 UV-B lamp, contaminated with UV-A and UV-C (74-1111 mJ cm-2), also induces peak levels after 12 h incubation at 37 degrees C but these levels persist to 36 h post UV irradiation. In all cases p53 levels start to return to normal by 48 h culture. A significant positive correlation is demonstrated between UV-B dose (47-1645 mJ cm-2) and p53 level (p < 0.01, R > 0.977) in explants cultured for 24 h at 37 degrees C post irradiation. The FS20 induces a 'UV-B' dose-dependent increase in p53 to a maximum from 370 to 1111 mJ cm-2. Similarly, solar simulated UV induces a plateau of peak p53 induction between 5 and 15 MED equivalents. Immunohistochemical analysis using microwave retrieval on 5 microns sections shows the same pattern of p53 staining with UV-B and solar UV insult, but proves unreliable as a method of quantification. These results suggest that the skin explant model may be a useful tool in the evaluation of UV-induced epidermal cell damage, providing a valuable alternative to in vivo studies. PMID:10392467

Davenport, V; Morris, J F; Motazed, R; Chu, A C

1999-04-01

370

Homogeneous photodegradation of C.I. Reactive Blue 4 using a photo-Fenton process under artificial and solar irradiation  

Microsoft Academic Search

The oxidation of C.I. Reactive Blue 4 (RB4) by photo-Fenton process mediated by ferrioxalate was investigated under artificial and solar irradiation. The RB4 degradation in acidic medium (pH 2.5) was evaluated by the decrease in Total Organic Carbon (TOC) content and color, measured by the decrease in chromophore absorption band (600nm). The influence of ferrioxalate and H2O2 concentrations on the

Patricia A. Carneiro; Raquel F. Pupo Nogueira; Maria Valnice B. Zanoni

2007-01-01

371

Photodegradation of 4-alkylphenols using BiVO 4 photocatalyst under irradiation with visible light from a solar simulator  

Microsoft Academic Search

A visible-light-driven photocatalyst, BiVO4, has been applied for degradation of a series of linear 4-n-alkylphenols under irradiation from a solar simulator. Degradation rates become faster with increasing alkyl chain length. Half-life of 4-n-nonylphenol (4-n-NP) is 18min, which is about eight times shorter than that of phenol. The rate law of disappearance for heptyl-, octyl- and nonylphenols exhibits zero-order kinetics. The

Shigeru Kohtani; Masaya Koshiko; Akihiko Kudo; Kunihiro Tokumura; Yasuhito Ishigaki; Akira Toriba; Kazuichi Hayakawa; Ryoichi Nakagaki

2003-01-01

372

Theology after contact: religion and extraterrestrial intelligent life.  

PubMed

The prospect of encountering extraterrestrial intelligent life raises important questions for religion and theology. Even if an actual encounter with extraterrestrials never actually takes place, or proves impractical, terrestrial religious thought already has resources that can render intelligible and allow us theologically to appreciate such an eventuality. PMID:11797759

Haught, J F

2001-12-01

373

A Fast Model for the Reconstruction of Spectral Solar Irradiance in the Near- and Mid-Ultraviolet  

NASA Astrophysics Data System (ADS)

We present a model for the reconstruction of spectral solar irradiance between 200 and 400 nm. This model is an extension of the total solar irradiance (TSI) model of Crouch et al. ( Astrophys. J. 677, 723, 2008) which is based on a data-driven Monte Carlo simulation of sunspot emergence, fragmentation, and erosion. The resulting time-evolving daily area distribution of magnetic structures of all sizes is used as input to a four-component irradiance model including contributions from the quiet Sun, sunspots, faculae, and network. In extending the model to spectral irradiance in the near- and mid-ultraviolet, the quiet Sun and sunspot emissivities are calculated from synthetic spectra at T eff=5750 K and 5250 K, respectively. Facular emissivities are calculated using a simple synthesis procedure proposed by Solanki and Unruh ( Astron. Astrophys. 329, 747, 1998). The resulting time series of ultraviolet flux is calibrated against the data from the SOLSTICE instrument on the Upper Atmospheric Research Satellite (UARS). Using a genetic algorithm, we invert quiet Sun corrections, profile of facular temperature variations with height, and network model parameters which yield the best fit to these data. The resulting best-fit time series reproduces quite well the solar-cycle timescale variations of UARS ultraviolet observations, as well as the short-timescale fluctuations about the 81 day running mean. We synthesize full spectra between 200 and 400 nm, and validate these against the spectra obtained by the ATLAS-1 and ATLAS-3 missions, finding good agreement, to better than 3 % at most wavelengths. We also compare the UV variability predicted by our reconstructions in the descending phase of sunspot cycle 23 to SORCE/SIM data as well as to other reconstructions. Finally, we use the model to reconstruct the time series of spectral irradiance starting in 1874, and investigate temporal correlations between pairs of wavelengths in the bands of interest for stratospheric chemistry and dynamics.

Bolduc, C.; Charbonneau, P.; Dumoulin, V.; Bourqui, M. S.; Crouch, A. D.

2012-08-01

374

Effects of solar irradiance forcing on the ocean circulation and sea-ice in the North Atlantic in an isopycnic coordinate ocean general circulation model  

NASA Astrophysics Data System (ADS)

The sensitivity of the ocean circulation to changes in solar irradiance is examined using an isopycnic coordinate, global ocean general circulation model (OGCM) coupled to a thermodynamic/dynamic sea-ice model. In the experiments, changes in the surface radiation forcing are calculated based on orbital data assuming that the atmospheric conditions are otherwise unchanged. Two sensitivity experiments are run with the ocean sea-ice model: one with high and one with low solar irradiance representative of the last interglacial and glacial periods, respectively. The results show that the Atlantic merdional overturning circulation (AMOC) is increased (reduced) in response to lower (higher) summer solar irradiance. It is found that changes in the Arctic sea-ice volume and area are the main reason for the response. For the low solar irradiance case, less sea-ice is melted in summer leading to a saltier Arctic Ocean. This saltier water is then advected into the sinking regions in the winter, enhancing the intermediate and deep water formation. For the high solar irradiance case, a similar, but opposite, response occurs. The results thus confirm that the AMOC is very sensitive to external forcing. It is suggested that the scheme used for calculating changes in solar irradiance could prove useful when conducting glacial inception studies with fully coupled atmosphere ocean models.

Helge Otter, Odd; Drange, Helge

2004-03-01

375

On the improbability of intelligent extraterrestrials  

NASA Astrophysics Data System (ADS)

Discussions relating to the prevalence of extraterrestrial life generally remain ambiguous due to the lack of a suitable model for the development of biology. In this paper a simple model is proposed based on neutral evolution theory which leads to quantitative values for the genome growth rate within a biosphere. It is hypothesised that the genome size is a measure of organism complexity and hence an indicator of the likelihood of intelligence. The calculations suggest that organisms with the complexity of human beings may be rare and only occur with a probability below once per galaxy.

Bond, A.

1982-05-01

376

Musical Structures and Search for Extraterrestrials  

NASA Astrophysics Data System (ADS)

Recent findings in cognitive phsychology indicate connections between human feelings and musical scales, on the one hand, and the laws of thermodynamics, on the other. The existence of such a deep correlations allows us to suggest the hypothesis that music is inherent not only to the human beings but to other sapient creatures as well. It is worth, thus, in our search for extraterrestrial civilizations to conduct a "musical" analysis of the spectra of "suspicious" objects. The results of such analysis of the Doppler spectrum of SS 433 will be presented in this paper.

Lefebvre, Vladimir A.

377

Using CAD software to simulate PV energy yield - The case of product integrated photovoltaic operated under indoor solar irradiation  

SciTech Connect

In this paper, we show that photovoltaic (PV) energy yields can be simulated using standard rendering and ray-tracing features of Computer Aided Design (CAD) software. To this end, three-dimensional (3-D) sceneries are ray-traced in CAD. The PV power output is then modeled by translating irradiance intensity data of rendered images back into numerical data. To ensure accurate results, the solar irradiation data used as input is compared to numerical data obtained from rendered images, showing excellent agreement. As expected, also ray-tracing precision in the CAD software proves to be very high. To demonstrate PV energy yield simulations using this innovative concept, solar radiation time course data of a few days was modeled in 3-D to simulate distributions of irradiance incident on flat, single- and double-bend shapes and a PV powered computer mouse located on a window sill. Comparisons of measured to simulated PV output of the mouse show that also in practice, simulation accuracies can be very high. Theoretically, this concept has great potential, as it can be adapted to suit a wide range of solar energy applications, such as sun-tracking and concentrator systems, Building Integrated PV (BIPV) or Product Integrated PV (PIPV). However, graphical user interfaces of 'CAD-PV' software tools are not yet available. (author)

Reich, N.H.; van Sark, W.G.J.H.M.; Turkenburg, W.C. [Dept. of Science, Technology and Society, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht (Netherlands); Sinke, W.C. [Dept. of Science, Technology and Society, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht (Netherlands); Energy Research Centre of the Netherlands (ECN), Petten (Netherlands)

2010-08-15

378

Cell performance and defect behavior in proton-irradiated lithium-counterdoped n(+)p silicon solar cells  

NASA Astrophysics Data System (ADS)

Lithium-counterdoped n(+)p silicon solar cells were irradiated by 10-MeV protons, and their performance was determined as a function of fluence. It was found that the cell with the highest lithium concentration exhibited the higher radiation resistance. Deep-level transient spectroscopy studies of deep-level defects were used to identify two lithium-related defects. Defect energy levels obtained after the present 10-MeV irradiations were found to be markedly different than those observed after previous 1-MeV electron irradiations. However, the present DLTS data are consistent with previous suggestion by Weinberg et al. (1984) of a lithium-oxygen interaction which tends to inhibit formation of an interstitial boron-oxygen defect.

Weinberg, I.; Stupica, J. W.; Swartz, C. K.; Goradia, C.

1986-09-01

379

TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.  

PubMed

Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates. PMID:20355842

Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

2009-10-01

380

A LUT-based approach to estimate surface solar irradiance by combining MODIS and MTSAT data  

NASA Astrophysics Data System (ADS)

In this paper, a new satellite-derived approach for obtaining instantaneous surface solar irradiance (SSI) by combining Moderate Resolution Imaging Spectroradiometer (MODIS) and Multifunctional Transport Satellite (MTSAT) data is presented and validated using one year pyranometer measurements from five stations in northern China. The approach is based on look-up tables created via comprehensive radiative transfer modeling to achieve high accuracy and high computational efficiency. The synergy of the multispectral sensor MODIS and the high-temporal-resolution geostationary satellite MTSAT enables the adequate use of multisource remote sensing information to determine the atmosphere and surface states, and thereby complements shortcomings of their own. Here we use MTSAT data to capture the changes of cloud fields in the atmosphere and use MODIS products to obtain the dynamic aerosol loading, water vapor content, surface reflectance, and other information. Meanwhile, on the basis of instantaneous retrieval results, the calculation of hourly average SSI is also explored. The preliminary validation demonstrates that both instantaneous and hourly SSIs can be produced accurately over northern China using this approach, and the retrieval quality of hourly SSI data is slightly better than that of instantaneous SSI data. However, in mountainous areas the results need further refinement.

Huang, Guanghui; Ma, Mingguo; Liang, Shunlin; Liu, Shaomin; Li, Xin

2011-11-01

381

Total Solar Irradiance at the 2006 Transit of Mercury and Application to Transiting-Exoplanet Observations  

NASA Astrophysics Data System (ADS)

Following our earlier work on the Total Solar Irradiance (TSI) at the 2004 transit of Venus, in which an 0.4 percent drop in TSI was readily detectable with the ACRIM3 instrument on NASA's ACRIMsat, we report on ACRIM3 observations of the 29 November 2006 transit of Mercury. We also observed the transit from Haleakala and from Sacramento Peak. Mercury's cross-sectional angular area is only 1/30th that of Venus's, so the expected drop in TSI was only 0.01 percent. As expected, this tiny drop was not detected, though detailed statistical analysis continues. Our Venus and Mercury transit observations provide closeup views of phenomena increasingly observed for exoplanets and provide examples by which one can assess the limits at which exoplanet discoveries can be made with the transit method. Acknowledgments: JMP's planetary occultation work and the POETS instrument (Portable Occultation, Eclipse, and Transit System) were funded in part by NASA Planetary Astronomy grants NNG04GE48G, NNG04GF25G, NNH04ZSS001N, and NNG05GG75G to M.I.T. and Williams College, and continues under NNX08AO50G. Our transit work was funded in part by the Committee for Research and Exploration of the National Geographic Society. ACRIMsat is supported by a grant from NASA to Columbia University.

Pasachoff, Jay M.; Schneider, G.; Willson, R. C.

2008-09-01

382

Study of swift heavy ion irradiation effect on indium tin oxide coated electrode for the dye-sensitized solar cell application  

Microsoft Academic Search

Our long term objective is to study the swift heavy ion (SHI) irradiation effect on photoanode of dye-sensitized solar cell (DSSC) with the aim to investigate the stability of DSSC component in space irradiations and possibility of improvement in efficiency of DSSC due to ion induced effects in oxide layer. The DSSC photoanode consists of three layers viz; transparent conducting

H. K. Singh; D. C. Agarwal; P. M. Chavhan; R. M. Mehra; Shruti Aggarwal; Pawan Kumar Kulriya; Ambuj Tripathi; D. K. Avasthi

2010-01-01

383

Reduced solar irradiance effects on net primary productivity (NPP) and the ? 13C and ? 18O values in plantations of Musa sp., Musaceae  

Microsoft Academic Search

Biomass accumulation (annual net primary productivity, NPP) in a plantation of Musa sp., Musaceae is linearly correlated with solar irradiance (IR) between 100 and 32% of ambient levels (NPP = 0.82 IR + 20.42, p < 0.01, for the normalized data). The irradiance effects are clearly reflected in the ?13C values of leaf organic matter that are also linearly correlated

Dan Yakir; Yair Israeli

1995-01-01

384

Simple Solar Spectral Model for Direct and Diffuse Irradiance on Horizontal and Tilted Planes at the Earth's Surface for Cloudless Atmospheres  

Microsoft Academic Search

In a previous work, we described a simple model for calculating direct normal and diffuse horizontal spectral solar irradiance for cloudless sky conditions. In this paper, we present a new simple model (SPCTRAL2) that incorporates improvements to the simple model approach and an algorithm for calculating spectral irradiance on tilted surfaces. The model was developed using comparisons with rigorous radiative

Richard E. Bird; Carol Riordan

1986-01-01

385

Investigating the Mechanism for the Formation of Nitrous Oxide [N2O(X 1Sigma+)] in Extraterrestrial Ices  

Microsoft Academic Search

The formation of nitrous oxide, N2O(X 1Sigma+), in interstellar space and in ices on Pluto and Triton has been experimentally investigated. A molecular nitrogen (N2) and carbon dioxide (CO2) ice mixture was irradiated at 10 K with 5 keV electrons to simulate the electronic interaction effects of Galactic cosmic-ray bombardment of extraterrestrial ice samples over a time of 5×106 yr.

Corey S. Jamieson; Chris J. Bennett; Alexander M. Mebel; Ralf I. Kaiser

2005-01-01

386

A New Solar Spectral Irradiance Reconstruction based on MGII and Neutral Monitoring Indices for Use in Climate Modelling  

NASA Astrophysics Data System (ADS)

For atmosphere and climate studies, the solar spectral irradiance may be necessary at a time where no data exist. Use of proxies is then mandatory. In order to represent the solar forcing as variable in chemistry-climate numerical models, we need consistent series of temporal solar total and spectral variability covering over the periods of interest. While measurements are available, there is currently no harmonized series with some understanding of its accuracy and precision that can be readily implemented in model simulations. In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly ?-400 nm region, and its variability, based on the Mg II index and neutron monitor data. This 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 ? (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. Then, the set of coefficients expressing the spectral variability can be applied to a chosen reference spectrum to reconstruct the solar spectra within a given time frame or a Mg II index values. The accuracy of this method is estimated by calculating the standard deviation between the measured spectra and their reconstruction. For the second step, the relationship between the Mg II index and the neutron monitor data is searched for the 30-year of Mg II index availability. Finally, the reconstruction at a given date consists in using the neutron monitor data at that date, derive the corresponding Mg II index and use the coefficients of SSI variability to obtain the SSI at that date using a chosen reference spectrum. One major advantage is that using technology of today, we can reconstruct the solar spectral irradiance consistently from today to times when cosmogenic isotope data are available. This calibration can be re-accessed at any time, if necessary. Reconstruction for the Maunder minimum will be shown as well as variation of stratospheric components concentration inferred by solar variability.

Thuillier, G.; Bolsée, D.; DeLand, M.; Melo, S. M. L.; Schmutz, W.; Shapiro, A.

2012-04-01

387

Evolution of Chromospheric Structures Derived from Ca II K Spectroheliograms: Implications for Solar Ultraviolet Irradiance Variability  

Microsoft Academic Search

Over 1400 National Solar Observatory Ca II K spectroheliograms are analyzed for solar structure evolution for the years 1980, 1985, 1987, 1988, 1989, and 1992 through 1996 July with about a 50% time coverage. This time period includes the maximum of solar cycle 21 and almost all phases of solar cycle 22. The spectral bandpass and spatial resolution of these

John R. Worden; Oran R. White; Thomas N. Woods

1998-01-01

388

Human utilization of subsurface extraterrestrial environments.  

PubMed

Caves have been used in the ancient past as shelter or habitat by many organisms (including humans). Since antiquity, humans have explored caves for the minerals they contain and sometimes for ceremonial purposes. Over the past century, caves have become the target of increasing exploration, scientific research, and recreation. The use of caves on extraterrestrial bodies for human habitation has been suggested by several investigators. Lunar lava tube bases received early attention because lava tubes were clearly visible in lunar images from the Apollo Era. More recently, Mars Observer Camera data has shown us clear evidence of large tubes visible in a number of volcanic regions on Mars. The budding field of cave geomicrobiology has direct application to questions about subsurface life on other planets. Caves contain many unusual organisms making their living from unlikely materials like manganese, iron, and sulfur. This makes caves and other subsurface habitats prime targets for astrobiological missions to Mars and possibly other bodies. We present the results of a completed Phase I and on-going Phase II NASA Institute for Advanced Concepts (NIAC) study that intensively examines the possibilities of using extraterrestrial caves as both a resource for human explorers and as a highly promising scientific target for both robotic and future human missions to Mars and beyond. PMID:12959139

Boston, P J; Frederick, R D; Welch, S M; Werker, J; Meyer, T R; Sprungman, B; Hildreth-Werker, V; Thompson, S L; Murphy, D L

2003-06-01

389

Do extraterrestrials have sex (and intelligence)?  

PubMed

This thought experiment addresses the range of possible evolved psychologies likely to be associated with extraterrestrial (ET) intelligence. The analysis rests on: (1) a number of assumptions shared by the SETI project; (2) recent arguments concerning convergent evolution; and (3) current theories of how intelligence evolved in our own species. It concludes that, regardless of how and which cognitive abilities arise initially, extraterrestrially they can develop into intelligence only if an amplification process involving a form of predation and/or sexual selection occurs. Depending on the amplification process, ETs may be xenophobic; however, it is more probable that they will be ethnocentric. Their ideas of reciprocity and fairness are likely to at least overlap with our own. They will definitely be culture-bearing and probably have two sexes, both of which are intelligent. Regardless of the degree of physical similarity of ETs to ourselves, convergence makes it likely that we will at least find their evolved psychology similar enough to our own for comprehension. PMID:10818627

Barkow, J H

2000-04-01

390

Extremophiles and the search for extraterrestrial life.  

PubMed

Extremophiles thrive in ice, boiling water, acid, the water core of nuclear reactors, salt crystals, and toxic waste and in a range of other extreme habitats that were previously thought to be inhospitable for life. Extremophiles include representatives of all three domains (Bacteria, Archaea, and Eucarya); however, the majority are microorganisms, and a high proportion of these are Archaea. Knowledge of extremophile habitats is expanding the number and types of extraterrestrial locations that may be targeted for exploration. In addition, contemporary biological studies are being fueled by the increasing availability of genome sequences and associated functional studies of extremophiles. This is leading to the identification of new biomarkers, an accurate assessment of cellular evolution, insight into the ability of microorganisms to survive in meteorites and during periods of global extinction, and knowledge of how to process and examine environmental samples to detect viable life forms. This paper evaluates extremophiles and extreme environments in the context of astrobiology and the search for extraterrestrial life. PMID:12530238

Cavicchioli, Ricardo

2002-01-01

391

Predicting the production rates of cosmogenic nuclides in extraterrestrial matter  

SciTech Connect

The production rates of nuclides made by the galactic and solar cosmic rays are important in the interpretations of measurements made with lunar samples, meteorites, and cosmic spherules. Production rates of cosmogenic nuclides have been predicted by a variety of methods that are reviewed in this paper, ranging from systematic studies of one or a group of meteorites to purely theoretical calculations. Production rates can vary with the chemical composition and the preatmospheric depth of the sample and with the size and shape of the object. While the production systematics for cosmogenic nuclides are fairly well known, our ability to predict their production rates can be improved, with a corresponding increase in the scientific return. Additional detailed studies of cosmogenic nuclides in extraterrestrial objects are needed, especially for fairly small and very large objects. Nuclides made in simulation experiments and cross sections for many major nuclear reactions should be measured. Such studies are especially needed for the long-lived radionuclides that have only recently become readily measurable by accelerator mass spectrometry. 34 refs., 5 figs.

Reedy, R.C.

1987-01-01

392

Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy  

NASA Astrophysics Data System (ADS)

Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines ( Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade.

Grifoni, D.; Carreras, G.; Zipoli, G.; Sabatini, F.; Dalla Marta, A.; Orlandini, S.

2008-11-01

393

Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy.  

PubMed

Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines (Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade. PMID:18594874

Grifoni, D; Carreras, G; Zipoli, G; Sabatini, F; Dalla Marta, A; Orlandini, S

2008-07-02

394

An artificial solar spectrum substantially alters plant development compared with usual climate room irradiance spectra.  

PubMed

Plant responses to the light spectrum under which plants are grown affect their developmental characteristics in a complicated manner. Lamps widely used to provide growth irradiance emit spectra which are very different from natural daylight spectra. Whereas specific responses of plants to a spectrum differing from natural daylight may sometimes be predictable, the overall plant response is generally difficult to predict due to the complicated interaction of the many different responses. So far studies on plant responses to spectra either use no daylight control or, if a natural daylight control is used, it will fluctuate in intensity and spectrum. An artificial solar (AS) spectrum which closely resembles a sunlight spectrum has been engineered, and growth, morphogenesis, and photosynthetic characteristics of cucumber plants grown for 13 d under this spectrum have been compared with their performance under fluorescent tubes (FTs) and a high pressure sodium lamp (HPS). The total dry weight of the AS-grown plants was 2.3 and 1.6 times greater than that of the FT and HPS plants, respectively, and the height of the AS plants was 4-5 times greater. This striking difference appeared to be related to a more efficient light interception by the AS plants, characterized by longer petioles, a greater leaf unfolding rate, and a lower investment in leaf mass relative to leaf area. Photosynthesis per leaf area was not greater for the AS plants. The extreme differences in plant response to the AS spectrum compared with the widely used protected cultivation light sources tested highlights the importance of a more natural spectrum, such as the AS spectrum, if the aim is to produce plants representative of field conditions. PMID:20202994

Hogewoning, Sander W; Douwstra, Peter; Trouwborst, Govert; van Ieperen, Wim; Harbinson, Jeremy

2010-03-04

395

Interactions of water stress and solar irradiance on the physiology and biochemistry of Ligustrum vulgare.  

PubMed

We studied the interactive effects of water stress and solar irradiance on physiological and biochemical traits in Ligustrum vulgare L., with special emphasis on antioxidant enzymes and flavonoids. Water relations, photosynthetic performance, plant growth, activities of antioxidant enzymes and of phenylalanine-ammonia-lyase, and concentrations of nonstructural carbohydrates and phenylpropanoids were measured in plants growing in 12% (shade) or 100% (sun) sunlight and supplied with 100 or 40% of daily evapotranspiration-demand over a 4-week period. The mild water stress treatment caused leaf water potential and relative water content to decline on average by -0.22 MPa and 4.5%, respectively. In response to the water stress treatment, photosynthetic rates decreased more in sun plants than in shade plants, likely because of declines in photosystem II photochemistry, apparent maximum rate of carboxylation and apparent maximum electron transport rate coupled with significant reductions in stomatal conductance. Antioxidant enzymatic activities, which were much greater in sun leaves than in shade leaves under well-watered conditions, increased (particularly the enzymatic activities associated with hydrogen peroxide removal) in response to water stress only in shade leaves. Antioxidant phenylpropanoids, particularly quercetin and luteolin derivatives, markedly increased in response to full sunlight irrespective of water treatment; however, antioxidant phenylpropanoid concentrations increased in response to water stress only in shade leaves. We suggest that: (1) assimilated carbon in sun plants was used largely to support an effective antioxidant system capable of countering water-stress-induced oxidative damage--an example of cross tolerance; and (2) in shade plants, carbon was also diverted from growth to counter oxidative damage driven by the mild water-stress treatment. Both findings are consistent with the nearly exclusive distribution of L. vulgare in well-watered, partially shaded Mediterranean areas. PMID:18381268

Guidi, L; Degl'Innocenti, E; Remorini, D; Massai, R; Tattini, M

2008-06-01

396

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

NASA Astrophysics Data System (ADS)

Satellite-derived assessments of surface downwelling solar irradiance are more and more used by engineering companies in solar energy. Performances are judged satisfactory for the time being. Nevertheless, requests for more accuracy are increasing, in particular in the spectral definition and in the decomposition of the global radiation into direct and diffuse radiations. One approach to reach this goal is to improve both the modelling of the radiative transfer and the quality of the inputs describing the optical state. Within their joint project Heliosat-4, DLR and MINES ParisTech have adopted this approach to create advanced databases of solar irradiance succeeding to the current ones HelioClim and SolEMi. Regarding the model, we have opted for libRadtran, a well-known model of proven quality. As many similar models, running libRadtran is very time-consuming when it comes to process millions or more pixels or grid cells. This is incompatible with real-time operational process. One may adopt the abacus approach, or look-up tables, to overcome the problem. The model is run for a limited number of cases, covering the whole range of values taken by the various inputs of the model. Abaci are such constructed. For each real case, the irradiance value is computed by interpolating within the abaci. In this way, real-time can be envisioned. Nevertheless, the computation of the abaci themselves requires large computing capabilities. In addition, searching the abaci to find the values to interpolate can be time-consuming as the abaci are very large: several millions of values in total. Moreover, it raises the extrapolation problem of parameter out-of-range during the utilisation of the abaci. Parameterisation, when possible, is a means to reduce the amount of computations to be made and subsequently, the computation effort to create the abaci, the size of the abaci, the extrapolation and the searching time. It describes in analytical manner and with a few parameters the change in irradiance with a specific variable. The communication discusses two parameterisations found in the literature. One deals with the solar zenith angle, the other with the altitude. We assess their performances in retrieving solar irradiance for 32 spectral bands, from 240 nm to 4606 nm. The model libRadtran is run to create data sets for all sun zenith angles (every 5 degrees) and all altitudes (every km). These data sets are considered as a reference. Then, for each parameterisation, we compute the parameters using two irradiance values for specific values of angle (e.g., 0 and 60 degrees) or altitude (e.g., 0 and 3 km). The parameterisations are then applied to other values of angle and altitude. Differences between these assessments and the reference values of irradiance are computed and analysed. We conclude on the level of performances of each parameterisation for each spectral band as well as for the total irradiance. We discuss the possible use of these parameterisations in the future method Heliosat-4 and possible improvements. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 218793 (MACC project).

Wald, L.; Blanc, Ph.

2010-09-01

397

Limitation of Ground-Based Estimates of Solar Irradiance Due to Atmospheric Variations.  

National Technical Information Service (NTIS)

Solar radiation is the major energy source for Earth's biosphere. Solar radiation directly affects physical, chemical, and biological processes on the Earth. It is the direct forcing for atmospheric and oceanic circulations, and climate. Understanding thi...

G. Wen R. F. Cahalan B. N. Holben

2004-01-01

398

[Current considerations around the search for extraterrestrial life].  

PubMed

In this paper, the current cosmological topics are considered: a) The fourth centenary celebration of Giordano Bruno's death at the Roman's inquisition stake. This eminent philosopher, based on the Coppernican Revolution, concibed the Cosmos as a infinite universe with innumerable inhabited worlds. He acted on reason to believe not only in extraterrestrial life but in extraterrestrial intelligent life. Here we write a few words in his memory and honour. b) The active project SETI@home in the framework of today's classic program "Search for Extra-Terrestrial Intelligence", by means of the reception of radioelectrical signals. c) Search for extrasolar planets. PMID:11209557

González de Posada, F

2000-01-01

399

Triggering of the Younger Dryas Cooling by Extraterrestrial Impact  

NASA Astrophysics Data System (ADS)

The enigmatic Younger Dryas (YD) cooling episode (12.9-11.5 ka) is unique to late Quaternary deglacials; its timing is unexplainable by orbital forcing because Northern Hemisphere insolation was increasing at that time. The abrupt onset of YD cooling coincided with, and was likely partially in consequence of reduction in north Atlantic thermohaline circulation (THC). Triggering of YD cooling has often been attributed to major diversion of freshwater outflow from the continental interior via newly opened outlets resulting from ice sheet melt-back. However, an alternative primary trigger for YD cooling is actively being sought because of problems related to the timing of outlet openings and the relative importance of the magnitude and timing of freshwater input into the ocean. We present evidence in support of the hypothesis that the primary trigger for YD cooling may have instead been an extraterrestrial impact (the YD impact event) over northern North America at 12.9 ka. This impact event is recorded in a diverse range of impact-related proxies within the widely distributed YDB layer that indicates continent-wide impact effects. YD cooling likely resulted both from a combination of short-term atmospheric processes due to the impact itself that reduced solar radiation and from reorganization of ocean circulation. The hypothesis also posits that the impact caused partial destabilization of northern ice sheets and the opening of freshwater conduits; ice sheet melting due in part to the deposition of impact related dust (i.e. albedo) on the ice sheets; freshening of Arctic and northern Atlantic surface waters, and resulting strong reduction in north Atlantic THC. The impact hypothesis for YD triggering explains the timing enigma of the YD episode and is consistent with much existing data: 1) Abrupt and dramatic switch in Lake Agassiz outflow at 12.9 ka away from the Mississippi River's southern outlet to newly-opened outlets to the east and/or north; 2) A major and abrupt drop in ice-margin lake levels at precisely the time of the impact, based on the chronostratigraphy at Lake Hind and supported by Lake Agassiz sediment records; 3) Evidence at the onset of YD cooling in northern Atlantic and Arctic sediment cores of widespread IRD (during Heinrich event H0) reflecting ice-rafting armadas, freshwater discharges and reduced sea-surface salinity that resulted from the partial destabilization and melting of the ice sheet; 4) Evidence for an anomalous peak in Greenland ice sheet margin melting at the onset of the YD during a time of abrupt ocean and atmosphere cooling. The YD impact event supports the concept that extraterrestrial impacts, even of such limited geographic extent, can significantly and abruptly affect global climate change. Comparison of the YD event with other even larger meltwater outflow events of the last deglacial that had limited affects on the THC, suggests that the YD cooling was not triggered solely by salinity-driven ocean circulation changes. Instead, short-term climate pertubations due to the impact likely played a key role in triggering initial cooling that was reinforced or enhanced by the ocean circulation changes. Thus, the YD climate episode would not have occurred in the absence of the YD extraterrestrial impact event.

Kennett, J. P.; Becker, L.; West, A.

2007-05-01

400

Evaluation of the performance of a meso-scale NWP model to forecast solar irradiance on Reunion Island for photovoltaic power applications  

NASA Astrophysics Data System (ADS)

Solar photovoltaic power is a predominant source of electrical power on Reunion Island, regularly providing near 30% of electrical power demand for a few hours per day. However solar power on Reunion Island is strongly modulated by clouds in small temporal and spatial scales. Today regional regulations require that new solar photovoltaic plants be combined with storage systems to reduce electrical power fluctuations on the grid. Hence cloud and solar irradiance forecasting becomes an important tool to help optimize the operation of new solar photovoltaic plants on Reunion Island. Reunion Island, located in the South West of the Indian Ocean, is exposed to persistent trade winds, most of all in winter. In summer, the southward motion of the ITCZ brings atmospheric instabilities on the island and weakens trade winds. This context together with the complex topography of Reunion Island, which is about 60 km wide, with two high summits (3070 and 2512 m) connected by a 1500 m plateau, makes cloudiness very heterogeneous. High cloudiness variability is found between mountain and coastal areas and between the windward, leeward and lateral regions defined with respect to the synoptic wind direction. A detailed study of local dynamics variability is necessary to better understand cloud life cycles around the island. In the presented work, our approach to explore the short-term solar irradiance forecast at local scales is to use the deterministic output from a meso-scale numerical weather prediction (NWP) model, AROME, developed by Meteo France. To start we evaluate the performance of the deterministic forecast from AROME by using meteorological measurements from 21 meteorological ground stations widely spread around the island (and with altitudes from 8 to 2245 m). Ground measurements include solar irradiation, wind speed and direction, relative humidity, air temperature, precipitation and pressure. Secondly we study in the model the local dynamics and thermodynamics that control cloud development and solar irradiance in order to define new predictors to improve probabilistic forecast of solar irradiance.

Kalecinski, Natacha; Haeffelin, Martial; Badosa, Jordi; Periard, Christophe

2013-04-01

401

Searches for electromagnetic signals from extraterrestrial beings  

NASA Astrophysics Data System (ADS)

The techniques and rationale used in six radio-frequency surveys to detect possible signals from extraterrestrial beings (ETs) are reviewed. Reception attempts have been made by pointing antennas at the stars within 80 light years, toward F, G, K, andd M main sequence stars, and binary star systems with component separation less than one-third or more than three times the radius of the habitable zone around the main star. All of the searches explored narrow bandwidths, with attention given to rapid variability. Stars exhibiting variability were re-examined for longer periods, using the 21 cm bandwidth, which is not used for transmissions on earth. The best spectrum analyzer in operation for ET signal search purposes has a capacity of 200,000 channels. Further studies may be carried out at the 10 micron IR wavelength, which could detect planetary-size construction projects by ET civilizations.

Zuckerman, B.

402

Testing a Claim of Extraterrestrial Technology  

NASA Astrophysics Data System (ADS)

In December 2004, members of The SETI League, Inc. and the Invitation to ETI group were called upon to evaluate, and ultimately perform laboratory testing of, a claim of extraterrestrial electromagnetic technology present on Earth. These tests were undertaken because, although the claims were highly questionable, the claimant himself seemed reasonably credible, and a positive outcome, though unlikely, could have tremendous payoffs. The claim was rigorously tested but this produced a null result. This paper explores the initial claim, our reaction to it, the evaluation process, the observed results, lessons learned, and our conclusions. Despite the outcome, it was felt that all concerned showed great professionalism, and applied scientific rigor to a challenging situation.

Schuch, H. P.; Tough, A.

403

Euhedral Metallic-Fe-Ni Grains in Extraterrestrial Samples.  

National Technical Information Service (NTIS)

Metallic Fe-Ni is rare in terrestrial rocks, being largely restricted to serpentinized peridotites and volcanic rocks that assimilated carbonaceous material. In contrast, metallic Fe-Ni is nearly ubiquitous among extraterrestrial samples (i.e., meteorites...

A. E. Rubin

1993-01-01

404

Space Eyeful: A Virtual Microscope for Extraterrestrial Samples  

NASA Astrophysics Data System (ADS)

In this contribution we describe the latest developments in producing a library of virtual microscope images of a range of extraterrestrial samples for public engagement with planetary and space sciences.

Anand, M.; Pearson, V. K.; Tindle, A. G.; Kelley, S. P.; Koeberl, C.; Smith, C. L.; Whalley, P. C.

2012-03-01