The Search for Extraterrestrial Life

NASA Astrophysics Data System (ADS)

Peter, Ulmschneider

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?

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

NASA Astrophysics Data System (ADS)

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

2009-12-01

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

Spectral solar UV irradiance data for cycle 21

NASA Astrophysics Data System (ADS)

DeLand, Matthew T.; Cebula, Richard P.

2001-10-01

The Nimbus 7 Solar Backscatter Ultraviolet (SBUV) instrument, which began taking data in November 1978, was the first instrument to make solar UV irradiance measurements covering both the minimum and maximum activity levels of a solar cycle. The currently archived irradiance data set was processed with an instrument characterization which fails to completely account for sensor degradation in the later part of the data record, thus limiting the accuracy of estimated long-term solar activity variations and the scientific value of the data. In this paper, we describe an improved Nimbus 7 SBUV spectral irradiance data set, which utilizes a more accurate model for instrument sensitivity and treats other time-dependent problems in the archived data. Estimated long-term irradiance changes during solar cycle 21 are 8.3(+/-2.6%) at 205 nm, and 4.9(+/-1.8)% at 240 nm. The revised Nimbus 7 SBUV irradiance data are in good agreement with predictions of solar cycle variations from the Mg II index proxy model. These solar irradiance changes are also consistent with overlapping irradiance data from the declining phase of solar cycle 21 measured by the Solar Mesosphere Explorer (SME). The Nimbus 7 SBUV irradiance data represent the earliest component of a 20+ year continuous record of solar spectral UV activity.

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

NASA Technical Reports Server (NTRS)

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.;

Reconstruction of solar UV irradiance since 1974

NASA Astrophysics Data System (ADS)

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

2009-09-01

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

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

NASA Astrophysics Data System (ADS)

Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

2016-09-01

Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

Solar Rotational Modulations of Spectral Irradiance and Correlations with the Variability of Total Solar Irradiance

NASA Technical Reports Server (NTRS)

Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

2016-01-01

Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

Solar Spectral Irradiance and Climate

NASA Technical Reports Server (NTRS)

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

2012-01-01

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.

Terrestrial solar spectral modeling. [SOLTRAN, BRITE, and FLASH codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bird, R.E.

The utility of accurate computer codes for calculating the solar spectral irradiance under various atmospheric conditions was recognized. New absorption and extraterrestrial spectral data are introduced. Progress is made in radiative transfer modeling outside of the solar community, especially for space and military applications. Three rigorous radiative transfer codes SOLTRAN, BRITE, and FLASH are employed. The SOLTRAN and BRITE codes are described and results from their use are presented.

Solar EUV irradiance for space weather applications

NASA Astrophysics Data System (ADS)

Viereck, R. A.

2015-12-01

Solar EUV irradiance is an important driver of space weather models. Large changes in EUV and x-ray irradiances create large variability in the ionosphere and thermosphere. Proxies such as the F10.7 cm radio flux, have provided reasonable estimates of the EUV flux but as the space weather models become more accurate and the demands of the customers become more stringent, proxies are no longer adequate. Furthermore, proxies are often provided only on a daily basis and shorter time scales are becoming important. Also, there is a growing need for multi-day forecasts of solar EUV irradiance to drive space weather forecast models. In this presentation we will describe the needs and requirements for solar EUV irradiance information from the space weather modeler's perspective. We will then translate these requirements into solar observational requirements such as spectral resolution and irradiance accuracy. We will also describe the activities at NOAA to provide long-term solar EUV irradiance observations and derived products that are needed for real-time space weather modeling.

Guide to solar reference spectra and irradiance models

NASA Astrophysics Data System (ADS)

Tobiska, W. Kent

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

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

PubMed

Schmitz, Birger; Häggström, Therese; Tassinari, Mario

2003-05-09

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

Ionospheric Change and Solar EUV Irradiance

NASA Astrophysics Data System (ADS)

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

2011-12-01

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.

Solar total and spectral irradiance reconstruction over last 9000 years

NASA Astrophysics Data System (ADS)

Wu, Chi-Ju; Usoskin, Ilya; Krivova, Natalie; Solanki, Sami K.

2016-07-01

Although the mechanisms of solar influence on Earth climate system are not yet fully understood, solar total and spectral irradiance are considered to be among the main determinants. Solar total irradiance is the total flux of solar radiative energy entering Earth's climate system, whereas the spectral irradiance describes this energy is distributed over the spectrum. Solar irradiance in the UV band is of special importance since it governs chemical processes in the middle and upper atmosphere. On timescales of the 11-year solar cycle and shorter, solar irradiance is measured by space-based instruments while models are needed to reconstruct solar irradiance on longer timescale. The SATIRE-M model (Spectral And Total Irradiance Reconstruction over millennia) is employed in this study to reconstruct solar irradiance from decadal radionuclide isotope data such as 14C and 10Be stored in tree rings and ice cores, respectively. A reconstruction over the last 9000 years will be presented.

Solar Total and Spectral Irradiance Reconstruction over Last 9000 Years

NASA Astrophysics Data System (ADS)

Wu, C. J.; Krivova, N.; Solanki, S. K.; Usoskin, I. G.

2016-12-01

Although the mechanisms of solar influence on Earth climate system are not yet fully understood, solar total and spectral irradiance are considered to be among the main determinants. Solar total irradiance is the total flux of solar radiative energy entering Earth's climate system, whereas the spectral irradiance describes this energy is distributed over the spectrum. Solar irradiance in the UV band is of special importance since it governs chemical processes in the middle and upper atmosphere. On timescales of the 11-year solar cycle and shorter, solar irradiance is measured by space-based instruments while models are needed to reconstruct solar irradiance on longer timescale. The SATIRE-M model (Spectral And Total Irradiance Reconstruction over millennia) is employed in this study to reconstruct solar irradiance from decadal radionuclide isotope data such as 14C and 10Be stored in tree rings and ice cores, respectively. A reconstruction over the last 9000 years will be presented.

A hybrid system for solar irradiance specification

NASA Astrophysics Data System (ADS)

Tobiska, W.; Bouwer, S.

2006-12-01

Space environment research and space weather operations require solar irradiances in a variety of time scales and spectral formats. We describe the development of solar irradiance characterization using four models and systems that are also used for space weather operations. The four models/systems include SOLAR2000 (S2K), SOLARFLARE (SFLR), APEX, and IDAR, which are used by Space Environment Technologies (SET) to provide solar irradiances from the soft X-rays through the visible spectrum. SFLR uses the GOES 0.1 0.8 nm X-rays in combination with a Mewe model subroutine to provide 0.1 30.0 nm irradiances at 0.1 nm spectral resolution, at 1 minute time resolution, and in a 6-hour XUV EUV spectral solar flare evolution forecast with a 7 minute latency and a 2 minute cadence. These irradiances have been calibrated with the SORCE XPS observations and we report on the inclusion of these irradiances into the S2K model. The APEX system is a real-time data retrieval system developed in conjunction with the University of Southern California Space Sciences Center (SSC) to provide SOHO SEM data processing and distribution. SSC provides the updated SEM data to the research community and SET provides the operational data to the space operations community. We describe how the SOHO SEM data, and especially the new S10.7 index, is being integrated directly into the S2K model for space weather operations. The IDAR system has been developed by SET to extract coronal hole boundaries, streamers, coronal loops, active regions, plage, network, and background (internetwork) features from solar images for comparison with solar magnetic features. S2K, SFLR, APEX, and IDAR outputs are integrated through the S2K solar irradiance platform that has become a hybrid system, i.e., a system that is able to produce irradiances using different processes, including empirical and physics-based models combined with real-time data integration.

Reconstruction of solar spectral irradiance since the Maunder minimum

NASA Astrophysics Data System (ADS)

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

2010-12-01

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-α 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%).

Classification of daily solar irradiation by fractional analysis of 10-min-means of solar irradiance

NASA Astrophysics Data System (ADS)

Harrouni, S.; Guessoum, A.; Maafi, A.

2005-02-01

This paper deals with fractal analysis of daily solar irradiances measured with a time step of 10 minutes at Golden and Boulder located in Colorado. The aim is to estimate the fractal dimensions in order to perform classification of daily solar irradiances. The estimated fractal dimension hat{D} and the clearness index KT are used as classification criteria. The results show that these criteria lead to three classes: clear sky, partially covered sky and overcast sky. The results also show that the evaluation of the fractal dimension of the irradiance signal based on a data set with 10 minutes time step is possible.

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

NASA Technical Reports Server (NTRS)

Bada, Jeffrey L.

2003-01-01

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

Modelling rotational and cyclical spectral solar irradiance variations

NASA Astrophysics Data System (ADS)

Unruh, Yvonne

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

Long-term reconstructions of total solar irradiance

NASA Astrophysics Data System (ADS)

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

2012-07-01

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.

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

NASA Technical Reports Server (NTRS)

Moore, Christopher S.; Chamberlin, Phillip Clyde; Hock, Rachel

2014-01-01

The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.

Solar Irradiance Variations on Active Region Time Scales

NASA Technical Reports Server (NTRS)

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

1984-01-01

The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

Reconstructions of solar irradiance on centennial time scales

NASA Astrophysics Data System (ADS)

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

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

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

NASA Technical Reports Server (NTRS)

Mueller, Robert L.

1987-01-01

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

Estimation of height-dependent solar irradiation and application to the solar climate of Iran

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samimi, J.

1994-05-01

An explicitly height-dependent model has been used to estimate the solar irradiation over Iran which has a vast range of altitudes. The parameters of the model have been chosen on general grounds and not by parameters best fitting to any of the available measured irradiation data in Iran. The estimated global solar irradiation on the horizontal surface shows a very good agreement (4.1% deviation) with the 17-year long pyranometric measurements in Tehran, and also, is in good agreement with other, shorter available measured data. The entire data base of the Iranian meteorological stations have been used to establish a simplemore » relation between the sunshine duration records and the cloud cover reports which can be utilized in solar energy estimations for sites with no sunshine duration recorders. Clear sky maps of Iran for direct solar irradiation on tracking, horizontal, and south-facing vertical planes are presented. The global solar irradiation map for horizontal surface with cloudiness is zoned into four irradiation zones. In about four-fifths of the land in Iran, the annual-mean daily global solar irradiation on horizontal surface ranges from 4.5 to 5.4 kWh/m[sup 2].« less

Improving photovoltaic performance through radiative cooling in both terrestrial and extraterrestrial environments.

PubMed

Safi, Taqiyyah S; Munday, Jeremy N

2015-09-21

The method of detailed balance, introduced by Shockley and Queisser, is often used to find an upper theoretical limit for the efficiency of semiconductor pn-junction based photovoltaics. Typically the solar cell is assumed to be at an ambient temperature of 300 K. In this paper, we describe and analyze the use of radiative cooling techniques to lower the solar cell temperature below the ambient to surpass the detailed balance limit for a cell in contact with an ideal heat sink. We show that by combining specifically designed radiative cooling structures with solar cells, efficiencies higher than the limiting efficiency achievable at 300 K can be obtained for solar cells in both terrestrial and extraterrestrial environments. We show that our proposed structure yields an efficiency 0.87% higher than a typical PV module at operating temperatures in a terrestrial application. We also demonstrate an efficiency advantage of 0.4-2.6% for solar cells in an extraterrestrial environment in near-earth orbit.

VIRGO: Experiment for helioseismology and solar irradiance monitoring

NASA Technical Reports Server (NTRS)

Froehlich, Claus; Andersen, Bo N.

1995-01-01

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

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

NASA Astrophysics Data System (ADS)

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

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

The Search for Extraterrestrial Intelligence in Earth's Solar Transit Zone.

PubMed

Heller, René; Pudritz, Ralph E

2016-04-01

Over the past few years, astronomers have detected thousands of planets and candidate planets by observing their periodic transits in front of their host stars. A related method, called transit spectroscopy, might soon allow studies of the chemical imprints of life in extrasolar planetary atmospheres. Here, we address the reciprocal question, namely, from where is Earth detectable by extrasolar observers using similar methods. We explore Earth's transit zone (ETZ), the projection of a band around Earth's ecliptic onto the celestial plane, where observers can detect Earth transits across the Sun. ETZ is between 0.520° and 0.537° wide due to the noncircular Earth orbit. The restricted Earth transit zone (rETZ), where Earth transits the Sun less than 0.5 solar radii from its center, is about 0.262° wide. We first compile a target list of 45 K and 37 G dwarf stars inside the rETZ and within 1 kpc (about 3260 light-years) using the Hipparcos catalogue. We then greatly enlarge the number of potential targets by constructing an analytic galactic disk model and find that about 10(5) K and G dwarf stars should reside within the rETZ. The ongoing Gaia space mission can potentially discover all G dwarfs among them (several 10(4)) within the next 5 years. Many more potentially habitable planets orbit dim, unknown M stars in ETZ and other stars that traversed ETZ thousands of years ago. If any of these planets host intelligent observers, they could have identified Earth as a habitable, or even as a living, world long ago, and we could be receiving their broadcasts today. The K2 mission, the Allen Telescope Array, the upcoming Square Kilometer Array, or the Green Bank Telescope might detect such deliberate extraterrestrial messages. Ultimately, ETZ would be an ideal region to be monitored by the Breakthrough Listen Initiatives, an upcoming survey that will constitute the most comprehensive search for extraterrestrial intelligence so far.

The Search for Extraterrestrial Intelligence in Earth's Solar Transit Zone

NASA Astrophysics Data System (ADS)

Heller, René; Pudritz, Ralph E.

2016-04-01

Over the past few years, astronomers have detected thousands of planets and candidate planets by observing their periodic transits in front of their host stars. A related method, called transit spectroscopy, might soon allow studies of the chemical imprints of life in extrasolar planetary atmospheres. Here, we address the reciprocal question, namely, from where is Earth detectable by extrasolar observers using similar methods. We explore Earth's transit zone (ETZ), the projection of a band around Earth's ecliptic onto the celestial plane, where observers can detect Earth transits across the Sun. ETZ is between 0.520° and 0.537° wide due to the noncircular Earth orbit. The restricted Earth transit zone (rETZ), where Earth transits the Sun less than 0.5 solar radii from its center, is about 0.262° wide. We first compile a target list of 45 K and 37 G dwarf stars inside the rETZ and within 1 kpc (about 3260 light-years) using the Hipparcos catalogue. We then greatly enlarge the number of potential targets by constructing an analytic galactic disk model and find that about 105 K and G dwarf stars should reside within the rETZ. The ongoing Gaia space mission can potentially discover all G dwarfs among them (several 104) within the next 5 years. Many more potentially habitable planets orbit dim, unknown M stars in ETZ and other stars that traversed ETZ thousands of years ago. If any of these planets host intelligent observers, they could have identified Earth as a habitable, or even as a living, world long ago, and we could be receiving their broadcasts today. The K2 mission, the Allen Telescope Array, the upcoming Square Kilometer Array, or the Green Bank Telescope might detect such deliberate extraterrestrial messages. Ultimately, ETZ would be an ideal region to be monitored by the Breakthrough Listen Initiatives, an upcoming survey that will constitute the most comprehensive search for extraterrestrial intelligence so far.

Evolution of the solar irradiance during the Holocene

NASA Astrophysics Data System (ADS)

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

2011-07-01

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

UV solar irradiance in observations and the NRLSSI and SATIRE-S models

NASA Astrophysics Data System (ADS)

Yeo, K. L.; Ball, W. T.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Morrill, J.

2015-08-01

Total solar irradiance and UV spectral solar irradiance has been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the variability to solar magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models provide the most comprehensive reconstructions of total and spectral solar irradiance over the period of satellite observation currently available. There is persistent controversy between the various measurements and models in terms of the wavelength dependence of the variation over the solar cycle, with repercussions on our understanding of the influence of UV solar irradiance variability on the stratosphere. We review the measurement and modeling of UV solar irradiance variability over the period of satellite observation. The SATIRE-S reconstruction is consistent with spectral solar irradiance observations where they are reliable. It is also supported by an independent, empirical reconstruction of UV spectral solar irradiance based on Upper Atmosphere Research Satellite/Solar Ultraviolet Spectral Irradiance Monitor measurements from an earlier study. The weaker solar cycle variability produced by NRLSSI between 300 and 400 nm is not evident in any available record. We show that although the method employed to construct NRLSSI is principally sound, reconstructed solar cycle variability is detrimentally affected by the uncertainty in the SSI observations it draws upon in the derivation. Based on our findings, we recommend, when choosing between the two models, the use of SATIRE-S for climate studies.

Solar irradiance dictates settlement timing and intensity of marine mussels

PubMed Central

Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X. Antón; Fernández-Reiriz, Mª José

2016-01-01

Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance. PMID:27384527

Solar irradiance dictates settlement timing and intensity of marine mussels

NASA Astrophysics Data System (ADS)

Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X. Antón; Fernández-Reiriz, Mª José

2016-07-01

Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance.

Evaluation of solar irradiance models for climate studies

NASA Astrophysics Data System (ADS)

Ball, William; Yeo, Kok-Leng; Krivova, Natalie; Solanki, Sami; Unruh, Yvonne; Morrill, Jeff

2015-04-01

Instruments on satellites have been observing both Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI), mainly in the ultraviolet (UV), since 1978. Models were developed to reproduce the observed variability and to compute the variability at wavelengths that were not observed or had an uncertainty too high to determine an accurate rotational or solar cycle variability. However, various models and measurements show different solar cycle SSI variability that lead to different modelled responses of ozone and temperature in the stratosphere, mainly due to the different UV variability in each model, and the global energy balance. The NRLSSI and SATIRE-S models are the most comprehensive reconstructions of solar irradiance variability for the period from 1978 to the present day. But while NRLSSI and SATIRE-S show similar solar cycle variability below 250 nm, between 250 and 400 nm SATIRE-S typically displays 50% larger variability, which is however, still significantly less then suggested by recent SORCE data. Due to large uncertainties and inconsistencies in some observational datasets, it is difficult to determine in a simple way which model is likely to be closer to the true solar variability. We review solar irradiance variability measurements and modelling and employ new analysis that sheds light on the causes of the discrepancies between the two models and with the observations.

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

PubMed

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

2011-11-01

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

White Paper on SBUV/2 Solar Irradiance Measurements

NASA Technical Reports Server (NTRS)

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

1996-01-01

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

Response of Solar Irradiance to Sunspot-area Variations

NASA Astrophysics Data System (ADS)

Dudok de Wit, T.; Kopp, G.; Shapiro, A.; Witzke, V.; Kretzschmar, M.

2018-02-01

One of the important open questions in solar irradiance studies is whether long-term variability (i.e., on timescales of years and beyond) can be reconstructed by means of models that describe short-term variability (i.e., days) using solar proxies as inputs. Preminger & Walton showed that the relationship between spectral solar irradiance and proxies of magnetic-flux emergence, such as the daily sunspot area, can be described in the framework of linear system theory by means of the impulse response. We significantly refine that empirical model by removing spurious solar-rotational effects and by including an additional term that captures long-term variations. Our results show that long-term variability cannot be reconstructed from the short-term response of the spectral irradiance, which questions the extension of solar proxy models to these timescales. In addition, we find that the solar response is nonlinear in a way that cannot be corrected simply by applying a rescaling to a sunspot area.

Influence of Solar Irradiance on Polar Ionospheric Convection

NASA Astrophysics Data System (ADS)

Burrell, A. G.; Yeoman, T. K.; Stephen, M.; Lester, M.

2016-12-01

Plasma convection over the poles shows the result of direct interactions between the terrestrial atmosphere, magnetosphere, and the sun. The paths that the ionospheric plasma takes in the polar cap form a variety of patterns, which have been shown to depend strongly on the direction of the Interplanetary Magnetic Field (IMF) and the reconnection rate. While the IMF and level of geomagnetic activity clearly alter the plasma convection patterns, the influence of changing solar irradiance is also important. The solar irradiance and magnetospheric particle precipitation regulate the rate of plasma production, and thus the ionospheric conductivity. Previous work has demonstrated how season alters the convection patterns observed over the poles, demonstrating the importance that solar photoionisation has on plasma convection. This study investigates the role of solar photoionisation on convection more directly, using measurements of ionospheric convection made by the Super Dual Auroral Radar Network (SuperDARN) and solar irradiance observations made by the Solar EUV Experiment (SEE) to explore the influence of the solar cycle on ionospheric convection, and the implications this may have on magnetosphere-ionosphere coupling.

Studies of Solar EUV Irradiance from SOHO

NASA Technical Reports Server (NTRS)

Floyd, Linton

2002-01-01

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

New solar irradiances for use in space research

NASA Astrophysics Data System (ADS)

Tobiska, W.; Bouwer, D.; Jones, A.

Space environment research applications require solar irradiances in a variety of time scales and spectral formats We describe the development of research grade modeled solar irradiances using four models and systems that are also used for space weather operations The four models systems include SOLAR2000 S2K SOLARFLARE SFLR APEX and IDAR which are used by Space Environment Technologies SET to provide solar irradiances from the soft X-rays through the visible spectrum SFLR uses the GOES 0 1--0 8 nm X-rays in combination with a Mewe model subroutine to provide 0 1--30 0 nm irradiances at 0 1 nm spectral resolution at 1 minute time resolution and in a 6-hour XUV--EUV spectral solar flare evolution forecast with a 7 minute latency and a 2 minute cadence These irradiances have been calibrated with the SORCE XPS observations and we report on the inclusion of these irradiances in the S2K model There are additional developments with S2K that we discuss particularly the method by which S2K is emerging as a hybrid model empirical plus physics-based and real-time data integration platform Numerous new solar indices have been recently developed for the operations community and we describe their inclusion in S2K The APEX system is a real-time data retrieval system developed under contract to the University of Southern California Space Sciences Center SSC to provide SOHO SEM data processing and distribution SSC provides the updated SEM data to the research community and SET provides the operational data to the space operations community We

A discussion of plausible solar irradiance variations, 1700-1992

NASA Technical Reports Server (NTRS)

Hoyt, Douglas V.; Schatten, Kenneth H.

1993-01-01

From satellite observations the solar total irradiance is known to vary. Sunspot blocking, facular emission, and network emission are three identified causes for the variations. In this paper we examine several different solar indices measured over the past century that are potential proxy measures for the Sun's irradiance. These indices are (1) the equatorial solar rotation rate, (2) the sunspot structure, the decay rate of individual sunspots, and the number of sunspots without umbrae, and (3) the length and decay rate of the sunspot cycle. Each index can be used to develop a model for the Sun's total irradiance as seen at the Earth. Three solar indices allow the irradiance to be modeled back to the mid-1700s. The indices are (1) the length of the solar cycle, (2) the normalized decay rate of the solar cycle, and (3) the mean level of solar activity. All the indices are well correlated, and one possible explanation for their nearly simultaneous variations is changes in the Sun's convective energy transport. Although changes in the Sun's convective energy transport are outside the realm of normal stellar structure theory (e.g., mixing length theory), one can imagine variations arising from even the simplest view of sunspots as vertical tubes of magnetic flux, which would serve as rigid pillas affecting the energy flow patterns by ensuring larger-scale eddies. A composite solar irradiance model, based upon these proxies, is compared to the northern hemisphere temperature depatures for 1700-1992. Approximately 71% of the decadal variance in the last century can be modeled with these solar indices, although this analysis does not include anthropogenic or other variations which would affect the results. Over the entire three centuries, approx. 50% of the variance is modeled. Both this analysis and previous similar analyses have correlations of model solar irradiances and measured Earth surface temperatures that are significant at better than the 95% confidence level

Solar spectral irradiance variability in cycle 24: observations and models

NASA Astrophysics Data System (ADS)

Marchenko, Sergey V.; DeLand, Matthew T.; Lean, Judith L.

2016-12-01

Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265 and 500 nm during the ongoing cycle 24. We supplement the OMI data with concurrent observations from the Global Ozone Monitoring Experiment-2 (GOME-2) and Solar Radiation and Climate Experiment (SORCE) instruments and find fair-to-excellent, depending on wavelength, agreement among the observations, and predictions of the Naval Research Laboratory Solar Spectral Irradiance (NRLSSI2) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models.

The demography of extraterrestrial civilizations

NASA Technical Reports Server (NTRS)

Billingham, J.

1981-01-01

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

Development, Production and Validation of the NOAA Solar Irradiance Climate Data Record

NASA Astrophysics Data System (ADS)

Coddington, O.; Lean, J.; Pilewskie, P.; Snow, M. A.; Lindholm, D. M.

2015-12-01

A new climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), including source code and supporting documentation is now publicly available as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program. Daily and monthly averaged values of TSI and SSI, with associated time and wavelength dependent uncertainties, are estimated from 1882 to the present with yearly averaged values since 1610, updated quarterly for the foreseeable future. The new Solar Irradiance Climate Data Record, jointly developed by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes from quiet Sun conditions when bright faculae and dark sunspots are present on the solar disk. The magnitudes of the irradiance changes that these features produce are determined from linear regression of the proxy Mg II index and sunspot area indices against the approximately decade-long solar irradiance measurements made by instruments on the SOlar Radiation and Climate Experiment (SORCE) spacecraft. We describe the model formulation, uncertainty estimates, operational implementation and validation approach. Future efforts to improve the uncertainty estimates of the Solar Irradiance CDR arising from model assumptions, and augmentation of the solar irradiance reconstructions with direct measurements from the Total and Spectral Solar Irradiance Sensor (TSIS: launch date, July 2017) are also discussed.

LISIRD: Where to go for Solar Irradiance Data

NASA Astrophysics Data System (ADS)

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

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

Long-term downward trend in total solar irradiance.

PubMed

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

1986-11-28

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

Advanced solar irradiances applied to satellite and ionospheric operational systems

NASA Astrophysics Data System (ADS)

Tobiska, W. Kent; Schunk, Robert; Eccles, Vince; Bouwer, Dave

Satellite and ionospheric operational systems require solar irradiances in a variety of time scales and spectral formats. We describe the development of a system using operational grade solar irradiances that are applied to empirical thermospheric density models and physics-based ionospheric models used by operational systems that require a space weather characterization. The SOLAR2000 (S2K) and SOLARFLARE (SFLR) models developed by Space Environment Technologies (SET) provide solar irradiances from the soft X-rays (XUV) through the Far Ultraviolet (FUV) spectrum. The irradiances are provided as integrated indices for the JB2006 empirical atmosphere density models and as line/band spectral irradiances for the physics-based Ionosphere Forecast Model (IFM) developed by the Space Environment Corporation (SEC). We describe the integration of these irradiances in historical, current epoch, and forecast modes through the Communication Alert and Prediction System (CAPS). CAPS provides real-time and forecast HF radio availability for global and regional users and global total electron content (TEC) conditions.

On the variation of the Nimbus 7 total solar irradiance

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

1992-01-01

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

Evaluation of the Applicability of Solar and Lamp Radiometric Calibrations of a Precision Sun Photometer Operating Between 300 and 1025 nm

NASA Technical Reports Server (NTRS)

Schmid, Beat; Spyak, Paul R.; Biggar, Stuart F.; Joerg, Sekler; Ingold, Thomas; Maetzler, Christian; Kaempfer, Niklaus

2000-01-01

Over a period of 3 year a precision Sun photometer (SPM) operating between 300 and 1025 nm was calibrated four times at three different high-mountain sites in Switzerland, Germany, and the United States by means of the Langley-plot technique. We found that for atmospheric window wavelengths the total error (2 sigma-statistical plus systematic errors) of the calibration constants V(sub 0)(lambda), the SPM voltage in the absence of any attenuating atmosphere, can be kept below 1.60% in the UV-A and blue, 0.9% in the mid-visible, and 0.6% in the near-infra red spectral region. For SPM channels within strong water-vapor or ozone absorption bands a modified Langley-plot technique was used to determine V(sub 0)(lambda) with a lower accuracy. Within the same period of time, we calibrated the SPM five times using irradiance standard lamps in the optical labs of the Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center, Switzerland, and of the Remote Sensing Group of the Optical Sciences Center, University of Arizona, Tucson, Arizona. The lab calibration method requires knowledge of the extraterrestrial spectral irradiance. When we refer the standard lamp results to the World Radiation Center extraterrestrial solar irradiance spectrum, they agree with the Langley results within 2% at 6 or 13 SPM wavelengths. The largest disagreement (4.4%) is found for the channel centered at 610 nm. The results of these intercomparisons change significantly when the lamp results are referred to two different extraterrestrial solar irradiance spectra that have become recently available.

Computation of glint, glare, and solar irradiance distribution

DOEpatents

Ho, Clifford Kuofei; Khalsa, Siri Sahib Singh

2017-08-01

Described herein are technologies pertaining to computing the solar irradiance distribution on a surface of a receiver in a concentrating solar power system or glint/glare emitted from a reflective entity. At least one camera captures images of the Sun and the entity of interest, wherein the images have pluralities of pixels having respective pluralities of intensity values. Based upon the intensity values of the pixels in the respective images, the solar irradiance distribution on the surface of the entity or glint/glare corresponding to the entity is computed.

Computation of glint, glare, and solar irradiance distribution

DOEpatents

Ho, Clifford Kuofei; Khalsa, Siri Sahib Singh

2015-08-11

Described herein are technologies pertaining to computing the solar irradiance distribution on a surface of a receiver in a concentrating solar power system or glint/glare emitted from a reflective entity. At least one camera captures images of the Sun and the entity of interest, wherein the images have pluralities of pixels having respective pluralities of intensity values. Based upon the intensity values of the pixels in the respective images, the solar irradiance distribution on the surface of the entity or glint/glare corresponding to the entity is computed.

Modelling total solar irradiance using a flux transport model

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Variations in solar Lyman alpha irradiance on short time scales

NASA Astrophysics Data System (ADS)

Pap, J. M.

1992-10-01

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

Variations in solar Lyman alpha irradiance on short time scales

NASA Technical Reports Server (NTRS)

Pap, J. M.

1992-01-01

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

Extraterrestrial Radiation Chemistry and Molecular Astronomy

NASA Technical Reports Server (NTRS)

Hudson, Reggie L.; Moore, Marla H.

2009-01-01

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

[Extraterrestrial influences on health and disease].

PubMed

Sitar, J

1994-02-14

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.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2011-08-01

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

Extraterrestrial intelligence? The search is on

NASA Technical Reports Server (NTRS)

Coulter, Gary R.

1991-01-01

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

Analysis of satellite-derived solar irradiance over the Netherlands

NASA Astrophysics Data System (ADS)

Dirksen, Marieke; Fokke Meirink, Jan; Sluiter, Raymond

2017-04-01

Measurements from geostationary satellites allow the retrieval of surface solar irradiance homogeneously over large areas, thereby providing essential information for the solar energy sector. In this paper, the SICCS solar irradiance data record derived from 12 years of Meteosat Second Generation satellite measurements is analysed with a focus on the Netherlands, where the spatial resolution is about 6 by 3 km2. Extensive validation of the SICCS data with pyranometer observations is performed, indicating a bias of approximately 3 W/m2 and RMSE of 11 W/m2 for daily data. Long term averages and seasonal variations of solar irradiance show regional patterns related to the surface type (e.g., coastal waters, forests, cities). The inter-annual variability over the time frame of the data record is quantified. Methods to merge satellite and surface observations into an optimized data record are explored.

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

NASA Astrophysics Data System (ADS)

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

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

ACRIM total solar irradiance monitoring during solar cycles 21 - 23

NASA Astrophysics Data System (ADS)

Willson, R.; Mordvinov, A.

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

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

NASA Astrophysics Data System (ADS)

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

2012-07-01

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

Possible Existence of Extra-Terrestrial Technology in the Solar System

NASA Astrophysics Data System (ADS)

Burke-Ward, R.

Potential features of the design and function of extra-terrestrial probes are discussed with the aim of establishing criteria for search, detection and contact. Probes are categorised according to three primary areas of function - data-gathering, direct action, and sentient entities. Conclusions are drawn about possible probe technologies and modes of behaviour.

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

PubMed

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

2013-11-20

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

An Empirical Model of the Variation of the Solar Lyman-α Spectral Irradiance

NASA Astrophysics Data System (ADS)

Kretzschmar, Matthieu; Snow, Martin; Curdt, Werner

2018-03-01

We propose a simple model that computes the spectral profile of the solar irradiance in the hydrogen Lyman alpha line, H Ly-α (121.567 nm), from 1947 to present. Such a model is relevant for the study of many astronomical environments, from planetary atmospheres to interplanetary medium. This empirical model is based on the SOlar Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation observations of the Ly-α irradiance over solar cycle 23 and the Ly-α disk-integrated irradiance composite. The model reproduces the temporal variability of the spectral profile and matches the independent SOlar Radiation and Climate Experiment/SOLar-STellar Irradiance Comparison Experiment spectral observations from 2003 to 2007 with an accuracy better than 10%.

Astrophysics with Extraterrestrial Materials

NASA Astrophysics Data System (ADS)

Nittler, Larry R.; Ciesla, Fred

2016-09-01

Extraterrestrial materials, including meteorites, interplanetary dust, and spacecraft-returned asteroidal and cometary samples, provide a record of the starting materials and early evolution of the Solar System. We review how laboratory analyses of these materials provide unique information, complementary to astronomical observations, about a wide variety of stellar, interstellar and protoplanetary processes. Presolar stardust grains retain the isotopic compositions of their stellar sources, mainly asymptotic giant branch stars and Type II supernovae. They serve as direct probes of nucleosynthetic and dust formation processes in stars, galactic chemical evolution, and interstellar dust processing. Extinct radioactivities suggest that the Sun's birth environment was decoupled from average galactic nucleosynthesis for some tens to hundreds of Myr but was enriched in short-lived isotopes from massive stellar winds or explosions shortly before or during formation of the Solar System. Radiometric dating of meteorite components tells us about the timing and duration over which solar nebula solids were assembled into the building blocks of the planets. Components of the most primitive meteoritical materials provide further detailed constraints on the formation, processing, and transport of material and associated timescales in the Sun's protoplanetary disk as well as in other forming planetary systems.

Solar Spectral Irradiance Variability in Cycle 24: Model Predictions and OMI Observations

NASA Technical Reports Server (NTRS)

Marchenko, S.; DeLand, M.; Lean, J.

2016-01-01

Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265-500 nanometers during the ongoing Cycle 24. We supplement the OMI data with concurrent observations from the GOME-2 (Global Ozone Monitoring Experiment - 2) and SORCE (Solar Radiation and Climate Experiment) instruments and find fair-to-excellent agreement between the observations and predictions of the NRLSSI2 (Naval Research Laboratory Solar Spectral Irradiance - post SORCE) and SATIRE-S (the Naval Research Laboratory's Spectral And Total Irradiance REconstruction for the Satellite era) models.

A reconstruction of solar irradiance using a flux transport model

NASA Astrophysics Data System (ADS)

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

2013-04-01

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.

Measuring Broadband IR Irradiance in the Direct Solar Beam (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, I.; Konings, J.; Xie, Y.

Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 micrometers and 50 micrometers, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 micrometers to 3 micrcometers, while the present photovoltaic cells are limited to approximately 0.3 micrometers to 1 micrometers. The broadband mismatch of ACR versusmore » such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus reference, yet calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 micrometers to 50 micrometers, as first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degres to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.« less

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

PubMed

Harrison, Albert A

2011-02-13

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.

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

NASA Technical Reports Server (NTRS)

Kendall, J. M., Sr.

1981-01-01

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

Coproduction of volatiles and metals from extraterrestrial materials

NASA Technical Reports Server (NTRS)

Lewis, John S.

1991-01-01

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

Extraterrestrial Life

NASA Technical Reports Server (NTRS)

Klein, M. J.

1993-01-01

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

Nonimaging solar concentrator with uniform irradiance

NASA Astrophysics Data System (ADS)

Winston, Roland; O'Gallagher, Joseph J.; Gee, Randy C.

2004-09-01

We report results of a study our group has undertaken under NREL/DOE auspices to design a solar concentrator with uniform irradiance on a planar target. This attribute is especially important for photovoltaic concentrators.

Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Continuing the Total and Spectral Solar Irradiance Climate Data Record

NASA Astrophysics Data System (ADS)

Coddington, O.; Pilewskie, P.; Kopp, G.; Richard, E. C.; Sparn, T.; Woods, T. N.

2017-12-01

Radiative energy from the Sun establishes the basic climate of the Earth's surface and atmosphere and defines the terrestrial environment that supports all life on the planet. External solar variability on a wide range of scales ubiquitously affects the Earth system, and combines with internal forcings, including anthropogenic changes in greenhouse gases and aerosols, and natural modes such as ENSO, and volcanic forcing, to define past, present, and future climates. Understanding these effects requires continuous measurements of total and spectrally resolved solar irradiance that meet the stringent requirements of climate-quality accuracy and stability over time. The current uninterrupted 39-year total solar irradiance (TSI) climate data record is the result of several overlapping instruments flown on different missions. Measurement continuity, required to link successive instruments to the existing data record to discern long-term trends makes this important climate data record susceptible to loss in the event of a gap in measurements. While improvements in future instrument accuracy will reduce the risk of a gap, the 2017 launch of TSIS-1 ensures continuity of the solar irradiance record into the next decade. There are scientific and programmatic motivations for addressing the challenges of maintaining the solar irradiance data record beyond TSIS-1. The science rests on well-founded requirements of establishing a trusted climate observing network that can monitor trends in fundamental climate variables. Programmatically, the long-term monitoring of solar irradiance must be balanced within the broader goals of NASA Earth Science. New concepts for a low-risk, cost efficient observing strategy is a priority. New highly capable small spacecraft, low-cost launch vehicles and a multi-decadal plan to provide overlapping TSI and SSI data records are components of a low risk/high reliability plan with lower annual cost than past implementations. This paper provides the

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

NASA Technical Reports Server (NTRS)

Heath, D. F.

1972-01-01

Satellite observations of the ultraviolet solar irradiance in selected wavelength bands between 1200 and 3000 a were made continuously by photometers consisting of broad-band sensors operated on Numbus 3 and 4 which were launched in April 1969 and 1970. In addition, spectrophotometer measurements of the solar irradiance were made with a dispersive instrument at 12 selected wavelengths from 2550 to 3400 a with a 10 a bandpass on Nimbus 4. Variations of the solar irradiance associated with the solar rotational period were observed since the launch of Nimbus 3. These variations are apparently associated with two source regions separated by about 180 deg in solar longitude. The change in irradiance with solar rotation was found to increase with decreasing wavelengths. Different types of the observed variations in uv solar irradiance can be classified in accordance with characteristics times, e.g. in the order of increasing periods as follows: (1)flare associated enhancements (2) 27-day variations due to solar rotation; (3) a possible biennial effect; and (4) long term variations associated with the 11-year solar cycle.

Stochastic Short-term High-resolution Prediction of Solar Irradiance and Photovoltaic Power Output

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melin, Alexander M.; Olama, Mohammed M.; Dong, Jin

The increased penetration of solar photovoltaic (PV) energy sources into electric grids has increased the need for accurate modeling and prediction of solar irradiance and power production. Existing modeling and prediction techniques focus on long-term low-resolution prediction over minutes to years. This paper examines the stochastic modeling and short-term high-resolution prediction of solar irradiance and PV power output. We propose a stochastic state-space model to characterize the behaviors of solar irradiance and PV power output. This prediction model is suitable for the development of optimal power controllers for PV sources. A filter-based expectation-maximization and Kalman filtering mechanism is employed tomore » estimate the parameters and states in the state-space model. The mechanism results in a finite dimensional filter which only uses the first and second order statistics. The structure of the scheme contributes to a direct prediction of the solar irradiance and PV power output without any linearization process or simplifying assumptions of the signal’s model. This enables the system to accurately predict small as well as large fluctuations of the solar signals. The mechanism is recursive allowing the solar irradiance and PV power to be predicted online from measurements. The mechanism is tested using solar irradiance and PV power measurement data collected locally in our lab.« less

Measuring Broadband IR Irradiance in the Direct Solar Beam and Recent Developments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, Ibrahim; Andreas, Afshin; Dooraghi, Mike

2016-12-14

Solar and atmospheric science radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference which is maintained by Absolute Cavity Radiometers (ACRs). An ACR is an open cavity with no window, developed to measure the extended broadband spectrum of the terrestrial direct solar beam irradiance that extends beyond the ultraviolet and infrared bands; i.e. below 0.2 um and above 50 um, respectively. On the other hand, the pyranometers and pyrheliometers were developed to measure broadband shortwave irradiance from approximately 0.3 um to 3 um, while the present photovoltaic cells are limited to the spectralmore » range of approximately 0.3 um to 1 um. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers, which measure the atmospheric longwave irradiance, are also used for solar and atmospheric science applications and calibrated with traceability to a consensus reference, yet they are calibrated during nighttime only, because no consensus reference has been established for the daytime longwave irradiance. This poster describes a method to measure the broadband longwave irradiance in the terrestrial direct solar beam from 3 um to 50 um, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The described method is used to measure the irradiance from sunrise to sunset; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 with an estimated uncertainty of 1.5 Wm-2, for a solar zenith angle range from 80 degrees to 16 degrees, respectively. Recent development shows that there is greater than 1.1 percent bias in measuring shortwave solar irradiance.« less

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

NASA Technical Reports Server (NTRS)

Timothy, J. G.

1983-01-01

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.

Results of the SOLCON FREESTAR Total Solar Irradiance measurements

NASA Astrophysics Data System (ADS)

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

2003-04-01

The measurement of the Total Solar Irradiance from space is ongoing since 1978. A long term series requires the combination of the time limited measurements of individual measurements. The accuracy of the long term series is limited by the absolute accuracy of the instruments, and by their ageing in space, due to exposure to UV radiation. As a reference for the combination of the different instruments, we use the measurements of the SOLar CONstant (SOLCON) instrument, which is flown regularly on the space shuttle. In this paper we will present the results of the most recent SOLCON flight, which is the Fast Reaction Experiments Enabling Science, Technology, Applications and Research (FREESTAR) flight foreseen from 16 Jan. 2003 to 1 Feb. 2003. The anticipated results are: 1) comparison of SOLCON with the new instruments Active Cavity Radiometer Irradiance Monitor (ACRIM) III, and 2) the Total Irradiance Monitor (TIM) on the Solar Radiation and Climate Experiment (SORCE) satellite, 3) verification of the ageing of the Variability of IRradiance and Gravity Oscillations (VIRGO) radiometers.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Luis; Marchante, Ruth; Cony, Marco

2010-10-15

Due to strong increase of solar power generation, the predictions of incoming solar energy are acquiring more importance. Photovoltaic and solar thermal are the main sources of electricity generation from solar energy. In the case of solar thermal energy plants with storage energy system, its management and operation need reliable predictions of solar irradiance with the same temporal resolution as the temporal capacity of the back-up system. These plants can work like a conventional power plant and compete in the energy stock market avoiding intermittence in electricity production. This work presents a comparisons of statistical models based on time seriesmore » applied to predict half daily values of global solar irradiance with a temporal horizon of 3 days. Half daily values consist of accumulated hourly global solar irradiance from solar raise to solar noon and from noon until dawn for each day. The dataset of ground solar radiation used belongs to stations of Spanish National Weather Service (AEMet). The models tested are autoregressive, neural networks and fuzzy logic models. Due to the fact that half daily solar irradiance time series is non-stationary, it has been necessary to transform it to two new stationary variables (clearness index and lost component) which are used as input of the predictive models. Improvement in terms of RMSD of the models essayed is compared against the model based on persistence. The validation process shows that all models essayed improve persistence. The best approach to forecast half daily values of solar irradiance is neural network models with lost component as input, except Lerida station where models based on clearness index have less uncertainty because this magnitude has a linear behaviour and it is easier to simulate by models. (author)« less

Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

NASA Technical Reports Server (NTRS)

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

2007-01-01

For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

Total solar irradiance values determined using Earth Radiation Budget Experiment (ERBE) radiometers

NASA Technical Reports Server (NTRS)

Lee, Robert B., III; Gibson, Michael A.; Natarajan, Sudha

1988-01-01

During the October 1984 through January 1988 period, the ERBE solar monitors on the NASA Earth Radiation Satellite and on the National Oceanic and Atmospheric Administration NOAA 9 and NOAA 10 spacecraft were used to obtain mean total solar irradiance values of 1365, 1365, and 1363 W/sq m, respectively. Secular variations in the solar irradiance have been observed, and they appear to be correlated with solar activity.

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

NASA Technical Reports Server (NTRS)

Pendleton, Yvonne J.; Cruikshank, Dale P.

1994-01-01

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

A I-V analysis of irradiated Gallium Arsenide solar cells

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Influence of synoptic weather patterns on solar irradiance variability in Europe

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

A lunar base for SETI (Search for Extraterrestrial Intelligence)

NASA Technical Reports Server (NTRS)

Oliver, Bernard M.

1988-01-01

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

Parameterization of daily solar global ultraviolet irradiation.

PubMed

Feister, U; Jäkel, E; Gericke, K

2002-09-01

Daily values of solar global ultraviolet (UV) B and UVA irradiation as well as erythemal irradiation have been parameterized to be estimated from pyranometer measurements of daily global and diffuse irradiation as well as from atmospheric column ozone. Data recorded at the Meteorological Observatory Potsdam (52 degrees N, 107 m asl) in Germany over the time period 1997-2000 have been used to derive sets of regression coefficients. The validation of the method against independent data sets of measured UV irradiation shows that the parameterization provides a gain of information for UVB, UVA and erythemal irradiation referring to their averages. A comparison between parameterized daily UV irradiation and independent values of UV irradiation measured at a mountain station in southern Germany (Meteorological Observatory Hohenpeissenberg at 48 degrees N, 977 m asl) indicates that the parameterization also holds even under completely different climatic conditions. On a long-term average (1953-2000), parameterized annual UV irradiation values are 15% and 21% higher for UVA and UVB, respectively, at Hohenpeissenberg than they are at Potsdam. Daily global and diffuse irradiation measured at 28 weather stations of the Deutscher Wetterdienst German Radiation Network and grid values of column ozone from the EPTOMS satellite experiment served as inputs to calculate the estimates of the spatial distribution of daily and annual values of UV irradiation across Germany. Using daily values of global and diffuse irradiation recorded at Potsdam since 1937 as well as atmospheric column ozone measured since 1964 at the same site, estimates of daily and annual UV irradiation have been derived for this site over the period from 1937 through 2000, which include the effects of changes in cloudiness, in aerosols and, at least for the period of ozone measurements from 1964 to 2000, in atmospheric ozone. It is shown that the extremely low ozone values observed mainly after the eruption of Mt

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, I.

2011-07-01

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 tomore » 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.« less

The moral status of extraterrestrial life.

PubMed

Persson, Erik

2012-10-01

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.

Finding extraterrestrial sites for thermophiles.

PubMed

Naylor, T

2004-04-01

Virtually our entire knowledge of the universe comes from two sorts of measurement of the electromagnetic radiation from the stars and galaxies within it; either their flux through relatively wide bandpasses (photometry), or measurements of the shape and wavelength of relatively narrow lines via spectroscopy. These techniques are now being used to discover planets outside our solar system, and perhaps in the next 10 years will begin to characterize them. If a serious search is to be made for extraterrestrial thermophiles, we need predictions for the effects of thermophiles on their host planets that are observable with these techniques. In this paper I shall outline what sorts of observation are likely to be used in the next 15 years for extra-solar planet work. All of the journal articles quoted here can be found through http://adsabs.harvard.edu/abstract_service.html, and often also accessed as preprints at http://uk.arxiv.org/form/astro%20ph?MULTI=form%20+/-%20interface.

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Toward Improved Modeling of Spectral Solar Irradiance for Solar Energy Applications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Yu; Sengupta, Manajit

This study introduces the National Renewable Energy Laboratory's (NREL's) recent efforts to extend the capability of the Fast All-sky Radiation Model for Solar applications (FARMS) by computing spectral solar irradiances over both horizontal and inclined surfaces. A new model is developed by computing the optical thickness of the atmosphere using a spectral irradiance model for clear-sky conditions, SMARTS2. A comprehensive lookup table (LUT) of cloud bidirectional transmittance distribution functions (BTDFs) is precomputed for 2002 wavelength bands using an atmospheric radiative transfer model, libRadtran. The solar radiation transmitted through the atmosphere is given by considering all possible paths of photon transmissionmore » and the relevent scattering and absorption attenuation. Our results indicate that this new model has an accuracy that is similar to that of state-of-the-art radiative transfer models, but it is significantly more efficient.« less

Total and Spectral Solar Irradiance Sensor (TSIS) Project Overview

NASA Technical Reports Server (NTRS)

Carlisle, Candace; Wedge, Ronnice; Wu, Dong; Stello, Harry; Robinson, Renee

2015-01-01

The main objective of the Total and Spectral solar Irradiance Sensor (TSIS) is to acquire measurements to determine the direct and indirect effects of solar radiation on climate. TSIS total solar irradiance measurements will extend a 37-year long uninterrupted measurement record of incoming solar radiation, the dominant energy source driving the Earths climate and the most precise indicator of changes in the Suns energy output. TSIS solar spectral irradiance measurements will determine the regions of the Earths multi-layered atmosphere that are affected by solar variability, from which the solar forcing mechanisms causing changes in climate can be quantified. TSIS includes two instruments: the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), integrated into a single payload. The TSIS TIM and SIM instruments are upgraded versions of the two instruments that are flying on the Solar Radiation and Climate Experiment (SORCE) mission launched in January 2003. TSIS was originally planned for the nadir-pointing National Polar-orbiting Operational Environmental Satellite System (NPOESS) spacecraft. The TSIS instrument passed a Critical Design Review (CDR) for NPOESS in December 2009. In 2010, TSIS was re-planned for the Joint Polar Satellite System (JPSS) Polar Free Flyer (PFF). The TSIS TIM, SIM, and associated electronics were built, tested, and successfully completed pre-ship review as of December 2013.In early 2014, NOAA and NASA agreed to fly TSIS on the International Space Station (ISS). In the FY16 Presidents Budget, NASA assumes responsibility for the TSIS mission on ISS. The TSIS project includes requirements, interface, design, build and test of the TSIS payload, including an updated pointing system, for accommodation on the ISS. It takes advantage of the prior development of the TSIS sensors and electronics. The International Space Station (ISS) program contributions include launch services and robotic installation of the TSIS payload

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

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

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

NASA Astrophysics Data System (ADS)

Munawwar, S.; Ghedira, H.

2012-12-01

Middle East's growing interest in renewable energy has led to increased activity in solar technology development with the recent commissioning of several utility-scale solar power projects and many other commercial installations across the Arabian Peninsula. The region, lying in a virtually rainless sunny belt with a typical daily average solar radiation exceeding 6 kWh/m2, is also one of the most promising candidates for solar energy deployment. However, it is not the availability of resource, but its characterization and reasonably accurate assessment that determines the application potential. Solar irradiance, magnitude and variability inclusive, is the key input in assessing the economic feasibility of a solar system. The accuracy of such data is of critical importance for realistic on-site performance estimates. This contribution aims to identify the key stages in developing a robust solar database for desert climate by focusing on the challenges that an arid environment presents to parameterization of solar irradiance attenuating factors. Adjustments are proposed based on the currently available resource assessment tools to produce high quality data for assessing bankability. Establishing and maintaining ground solar irradiance measurements is an expensive affair and fairly limited in time (recently operational) and space (fewer sites) in the Gulf region. Developers within solar technology industry, therefore, rely on solar radiation models and satellite-derived data for prompt resource assessment needs. It is imperative that such estimation tools are as accurate as possible. While purely empirical models have been widely researched and validated in the Arabian Peninsula's solar modeling history, they are known to be intrinsically site-specific. A primal step to modeling is an in-depth understanding of the region's climate, identifying the key players attenuating radiation and their appropriate characterization to determine solar irradiance. Physical approach

Quarantine provisions for unmanned extra-terrestrial missions

NASA Technical Reports Server (NTRS)

1976-01-01

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

A technique for global monitoring of net solar irradiance at the ocean surface. I - Model

NASA Technical Reports Server (NTRS)

Frouin, Robert; Chertock, Beth

1992-01-01

An accurate long-term (84-month) climatology of net surface solar irradiance over the global oceans from Nimbus-7 earth radiation budget (ERB) wide-field-of-view planetary-albedo data is generated via an algorithm based on radiative transfer theory. Net surface solar irradiance is computed as the difference between the top-of-atmosphere incident solar irradiance (known) and the sum of the solar irradiance reflected back to space by the earth-atmosphere system (observed) and the solar irradiance absorbed by atmospheric constituents (modeled). It is shown that the effects of clouds and clear-atmosphere constituents can be decoupled on a monthly time scale, which makes it possible to directly apply the algorithm with monthly averages of ERB planetary-albedo data. Compared theoretically with the algorithm of Gautier et al. (1980), the present algorithm yields higher solar irradiance values in clear and thin cloud conditions and lower values in thick cloud conditions.

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

NASA Astrophysics Data System (ADS)

Junk, Jürgen; Feister, Uwe; Helbig, Alfred

2007-08-01

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.

The solar spectral irradiances from x ray to radio wavelengths

NASA Technical Reports Server (NTRS)

White, O. R.

1993-01-01

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

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

NASA Technical Reports Server (NTRS)

Lee, Robert B., III

1992-01-01

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

Total and Spectral Solar Irradiance Sensor (TSIS) Project Status

NASA Technical Reports Server (NTRS)

Carlisle, Candace

2018-01-01

TSIS-1 studies the Sun's energy input to Earth and how solar variability affects climate. TSIS-1 will measure both the total amount of light that falls on Earth, known as the total solar irradiance (TSI), and how that light is distributed among ultraviolet, visible and infrared wavelengths, called solar spectral irradiance (SSI). TSIS-1 will provide the most accurate measurements of sunlight and continue the long-term climate data record. TSIS-1 includes two instruments: the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), integrated into a single payload on the International Space Station (ISS). The TSIS-1 TIM and SIM instruments are upgraded versions of the two instruments that are flying on the Solar Radiation and Climate Experiment (SORCE) mission launched in January 2003. NASA Goddard's TSIS project responsibilities include project management, system engineering, safety and mission assurance, and engineering oversight for TSIS-1. TSIS-1 was installed on the International Space Station in December 2017. At the end of the 90-day commissioning phase, responsibility for TSIS-1 operations transitions to the Earth Science Mission Operations (ESMO) project at Goddard for its 5-year operations. NASA contracts with the University of Colorado Laboratory for Atmospheric and Space Physics (LASP) for the design, development and testing of TSIS-1, support for ISS integration, science operations of the TSIS-1 instrument, data processing, data evaluation, calibration and delivery to the Goddard Earth Science Data and Information Services Center (GES DISC).

Quality assessment of solar UV irradiance measured with array spectroradiometers

NASA Astrophysics Data System (ADS)

Egli, Luca; Gröbner, Julian; Hülsen, Gregor; Bachmann, Luciano; Blumthaler, Mario; Dubard, Jimmy; Khazova, Marina; Kift, Richard; Hoogendijk, Kees; Serrano, Antonio; Smedley, Andrew; Vilaplana, José-Manuel

2016-04-01

The reliable quantification of ultraviolet (UV) radiation at the earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers (ASRMs) are small, light, robust and cost-effective instruments, and are increasingly used for spectral irradiance measurements. Within the European EMRP ENV03 project "Solar UV", new devices, guidelines and characterization methods have been developed to improve solar UV measurements with ASRMs, and support to the end user community has been provided. In order to assess the quality of 14 end user ASRMs, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the blind intercomparison revealed that ASRMs, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema-weighted UV index - in particular at large solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available ASRMs within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range of solar zenith angles. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 and 400 nm under all atmospheric conditions.

Quality assessment of solar UV irradiance measured with array spectroradiometers

NASA Astrophysics Data System (ADS)

Egli, L.; Gröbner, J.; Hülsen, G.; Bachmann, L.; Blumthaler, M.; Dubard, J.; Khazova, M.; Kift, R.; Hoogendijk, K.; Serrano, A.; Smedley, A. R. D.; Vilaplana, J.-M.

2015-12-01

The reliable quantification of ultraviolet (UV) radiation at the Earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers are small, light, robust and cost effective instruments and are increasingly used for spectral irradiance measurements. Within the European EMRP-ENV03 project "Solar UV", new devices, guidelines, and characterization methods have been developed to improve solar UV measurements with array spectroradiometers and support to the end-user community has been provided. In order to assess the quality of 14 end-user array spectroradiometers, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the intercomparison revealed that array spectroradiometers, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema weighted UV index - in particular at low solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available array spectroradiometer within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range or solar zenith angle. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 to 400 nm under all atmospheric conditions.

Measurements of the Solar Spectral Irradiance Variability over Solar Cycles 21 to 24

NASA Astrophysics Data System (ADS)

Woods, T. N.

2017-12-01

The solar irradiance is the primary natural energy input into Earth's atmosphere and climate system. Understanding the long-term variations of the solar spectral irradiance (SSI) over time scales of the 11-year solar activity cycle and longer is critical for most Sun-climate research topics. There are satellite measurements of the SSI since the 1970s that contribute to understanding the solar cycle variability over Solar Cycles 21 to 24. A limiting factor for the accuracy of these results is the uncertainties for the instrument degradation corrections, for which there are fairly large corrections relative to the amount of solar cycle variability at some wavelengths. A summary of these satellite SSI measurements, which are primarily in the ultraviolet and only recently in the visible and near infrared, will be presented. Examining SSI trends using a new analysis technique is helping to identify some uncorrected instrumental trends, which once applied to the SSI trends has the potential to provide more accurate solar cycle variability results. This new technique examines the SSI trends at different levels of solar activity to provide long-term trends in a SSI record, and one of the most common components of these derived long-term trends is a downward trend that we attribute to being most likely from uncorrected instrument degradation. Examples of this analysis will be presented for some of the satellite SSI measurements to demonstrate this new technique and how it has potential to improve the understanding of solar cycle variability and to clarify the uncertainties of the trends.

Mechanistical Studies on the Irradiation of Methanol in Extraterrestrial Ices

NASA Astrophysics Data System (ADS)

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

2007-05-01

Pure ices of amorphous methanol, CH3OH(X1A'), were irradiated at 11 K by 5 keV electrons at 100 nA for 1 hr. These energetic electrons simulate electronic energy transfer processes that occur as interstellar ices, comets, and icy solar system bodies are subjected to irradiation from MeV ions and secondary electrons produced in this process. The results were analyzed quantitatively via absorption-reflection-absorption Fourier transform infrared (FTIR) spectroscopy, with the identification of new species aided by high-level electronic structure calculations. The unimolecular decomposition of methanol was found to proceed via the formation of (1) the hydroxymethyl radical, CH2OH(X2A''), and atomic hydrogen, H(2S1/2), (2) the methoxy radical, CH3O(X2A'), plus atomic hydrogen, (3) formaldehyde, H2CO(X1A1) plus molecular hydrogen, H2(X1Σ+g), and (4) the formation of methane, CH4(X1A1), together with atomic oxygen, O(1D). The accessibility of the last channel indicates that the reverse process, oxygen addition into methane to form methanol, should also be feasible. A kinetic model is presented for the decomposition of methanol into these species, as well as the formyl radical, HCO(X2A'), and carbon monoxide, CO(X1Σ+). During the subsequent warming up of the sample, radicals previously generated within the matrix were mobilized and found to recombine to form methyl formate, CH3OCHO(X1A'), glycolaldehyde, CH2OHCHO(X1A'), and ethylene glycol, HOCH 2CH2OH(X1A). Upper limits for the production of these species by the recombination of neighboring radicals produced during irradiation as well as during the warm-up procedure are presented. The generation of these molecules by irradiation of ices in the solid state and their subsequent sublimation into the gas phase can help explain their high abundances as observed toward hot molecular cores and underlines their importance in astrobiology.

Solar Spectral Irradiance at 782 nm as Measured by the SES Sensor Onboard Picard

NASA Astrophysics Data System (ADS)

Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki, S.; Damé, L.; Bolsée, D.; Pereira, N.

2016-04-01

Picard is a satellite dedicated to the simultaneous measurement of the total and solar spectral irradiance, the solar diameter, the solar shape, and to the Sun's interior through the methods of helioseismology. The satellite was launched on June 15, 2010, and pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the satellite. The SES sensor produced an image of the Sun at 782 ± 2.5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782 nm from 2010 to 2014. During this period of Solar Cycle 24, the amplitude of the changes has been of the order of ± 0.08 %, corresponding to a range of about 2× 10^{-3} W m^{-2} nm^{-1}. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm. SES data show similar amplitude variations with the semi-empirical model Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S), whereas the Spectral Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and Climate Experiment satellite (SORCE) highlights higher amplitudes.

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

NASA Technical Reports Server (NTRS)

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

2009-01-01

In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

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

NASA Astrophysics Data System (ADS)

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

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

Elimination of disinfection byproduct formation potential in reclaimed water during solar light irradiation.

PubMed

Qian-Yuan, Wu; Chao, Li; Ye, Du; Wen-Long, Wang; Huang, Huang; Hong-Ying, Hu

2016-05-15

Ecological storage of reclaimed water in ponds and lakes is widely applied in water reuse. During reclaimed water storage, solar light can degrade pollutants and improve water quality. This study investigated the effects of solar light irradiation on the disinfection byproduct formation potential in reclaimed water, including haloacetonitriles (HANs), trichloronitromethane (TCNM), trihalomethanes (THMs), haloketones (HKs) and chloral hydrate (CH). Natural solar light significantly decreased the formation potential of HANs, TCNM, and HKs in reclaimed water, but had a limited effect on the formation potential of THMs and CH. Ultraviolet (UV) light in solar radiation played a dominant role in the decrease of the formation potential of HANs, TCNM and HKs. Among the disinfection byproducts, the removal kinetic constant of dichloroacetonitrile (DCAN) with irradiation dose was much larger than those for dichloropropanone (1,1-DCP), trichloropropanone (1,1,1-TCP) and TCNM. During solar irradiation, fluorescence spectra intensities of reclaimed water also decreased significantly. The removal of tyrosine (Tyr)-like and tryptophan (Trp)-like protein fluorescence spectra intensity volumes was correlated to the decrease in DCAN formation potential. Solar irradiation was demonstrated to degrade Trp, Tyr and their DCAN formation potential. The photolysis products of Trp after solar irradiation were detected as kynurenine and tryptamine, which had chloroform, CH and DCAN formation potential lower than those of Trp. Copyright © 2016. Published by Elsevier Ltd.

Exposure amount and timing of solar irradiation during pregnancy and the risk of sensitization in children.

PubMed

Koh, Hyun Yong; Cho, Eunhae; Lee, So-Yeon; Kim, Woo Kyung; Park, Yong Mean; Kim, Jihyun; Ahn, Kangmo; Lee, Seung Won; Kim, Mi Ae; Hahm, Myung-Il; Chae, Yoomi; Lee, Kee-Jae; Kwon, Ho-Jang; Han, Man Yong

2018-04-01

Solar irradiation affects sensitization to aeroallergens and the prevalence of allergic diseases. Little is known, however, about how the time and amount of solar irradiation during pregnancy affects such risks in children. We aimed to find out how solar irradiation during pregnancy affects sensitization to aero-allergens and the prevalence of allergic diseases in children. This population-based cross-sectional study involved 7301 aged 6 years and aged 12 years children. Maternal exposure to solar irradiation during pregnancy was evaluated using data from weather stations closest to each child's birthplace. Monthly average solar irradiation during the second and third trimesters was calculated with rank by quartiles. Risks of allergic sensitization and allergic disease were estimated. Relative to the first (lowest) quartile, the adjusted odds ratio (aOR) for allergic sensitization in the fourth (highest) quartile was lowest within solar irradiation during pregnancy months 5-6 (aOR = 0.823, 95% CI 0.720-0.942, p < 0.05). During months 9-10, the aOR for allergic sensitization for the fourth was higher than the first quartile of solar irradiation (aOR = 1.167, 95% CI 1.022-1.333, p < 0.05). Similar results were observed when solar irradiation was analyzed as a continuous variable during months 5 (aOR = 0.975, 95% CI 0.962-0.989, p < 0.001) and month 9 (aOR = 1.018, 95% CI 1.004-1.031, p = 0.003). Increased solar irradiation during months 7-8 increased the risk of asthma (aOR = 1.309, 95% CI 1.024-1.674, p = 0.032). Maternal exposure to solar irradiation during the second trimester of pregnancy associated with reduced aeroallergen sensitization, whereas solar irradiation during the third trimester was related to increased sensitization to aeroallergens. Copyright © 2017 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

Solar Arrays for Low-Irradiance Low-Temperature and High-Radiation Environments

NASA Technical Reports Server (NTRS)

Boca, Andreea (Principal Investigator); Stella, Paul; Kerestes, Christopher; Sharps, Paul

2017-01-01

This is the Base Period final report DRAFT for the JPL task 'Solar Arrays for Low-Irradiance Low-Temperature and High-Radiation Environments', under Task Plan 77-16518 TA # 21, for NASA's Extreme Environments Solar Power (EESP) project. This report covers the Base period of performance, 7/18/2016 through 5/2/2017.The goal of this project is to develop an ultra-high efficiency lightweight scalable solar array technology for low irradiance, low temperature and high-radiation (LILT/Rad) environments. The benefit this technology will bring to flight systems is a greater than 20 reduction in solar array surface area, and a six-fold reduction in solar array mass and volume. The EESP project objectives are summarized in the 'NRA Goal' column of Table 1. Throughout this report, low irradiance low temperature (LILT) refers to 5AU -125 C test conditions; beginning of life (BOL) refers to the cell state prior to radiation exposure; and end of life (EOL) refers to the test article condition after exposure to a radiation dose of 4e15 1MeV e(-)/cm(exp 2).

The new climate data record of total and spectral solar irradiance: Current progress and future steps

NASA Astrophysics Data System (ADS)

Coddington, Odele; Lean, Judith; Rottman, Gary; Pilewskie, Peter; Snow, Martin; Lindholm, Doug

2016-04-01

We present a climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. TSI and SSI are constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor (TIM), Spectral Irradiance Monitor (SIM), and SOlar Stellar Irradiance Comparison Experiment (SOLSTICE). We show that TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales and we assume that SSI measurements are reliable on solar rotational time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled TSI and SSI with the measurement record and with other solar irradiance models. We also discuss ongoing work to assess the sensitivity of the modeled irradiances to model assumptions, namely, the scaling of solar variability from rotational-to-cycle time scales and the representation of the sunspot darkening index.

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

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Measuring Broadband IR Irradiance in the Direct Solar Beam and Recent Development

NASA Astrophysics Data System (ADS)

Reda, I.; Andreas, A.; Dooraghi, M.; Habte, A.; Sengupta, M.; Kutchenreiter, M.

2016-12-01

Solar and atmospheric science radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to consensus Reference, which is maintained by Absolute Cavity Radiometers (ACRs). An ACR is an open cavity with no window, and developed to measure extended broadband spectrum of the terrestrial direct solar beam irradiance, extends beyond the ultraviolet and infrared bands; i.e. below 0.2 µm and above 50 µm, respectively. On the other hand, the pyranometers and pyrheliometers were developed to measure broadband shortwave irradiance from approximately 0.3 µm to 3 µm, while the present photovoltaic cells are limited to the spectral range of approximately 0.3 µm to 1 µm. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus Reference, yet they are calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster describes a method to measure the broadband longwave irradiance in the terrestrial direct solar beam from 3 µm to 50 µm, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The described method is used to measure the irradiance from sunrise to sunset; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 with an estimated uncertainty of 1.5 Wm-2, for a solar zenith angle range from 80° to 16°, respectively.

Extraterrestrial Organic Chemistry: From the Interstellar Medium to the Origins of Life

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Extraterrestrially delivered organics in the origin of cellular life. Various processes leading to the emergence of cellular life from organics delivered from space to earth or other planetary bodies in the solar system will be reviewed. The focus will be on: (1) self-assembly of amphiphilic material to vesicles and other structures, such as micelles and multilayers, and its role in creating environments suitable for chemical catalysis, (2) a possible role of extraterrestrial delivery of organics in the formation of the simplest bioenergetics (3) mechanisms leading from amino acids or their precursors to simple peptides and, subsequently, to the evolution of metabolism. These issues will be discussed from two opposite points of view: (1) Which molecules could have been particularly useful in the protobiological evolution; this may provide focus for searching for these molecules in interstellar media. (2) Assuming that a considerable part of the inventory of organic matter on the early earth was delivered extraterrestrially, what does relative abundance of different organics in space tell us about the scenario leading to the origin of life.

The Measurement of the Solar Spectral Irradiance Variability at 782 nm during the Solar Cycle 24 using the SES on-board PICARD

NASA Astrophysics Data System (ADS)

Meftah, Mustapha; Hauchecorne, Alain; Irbah, Abdanour; Bekki, Slimane

2016-04-01

A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the PICARD satellite. The SES sensor produced an image of the Sun at 782+/-5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782nm from 2010 to 2014. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm during the solar cycle 24. Comparisons will be made with Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) semi-empirical model and with the Spectral Irradiance Monitor instrument (SIM) on-board the Solar Radiation and Climate Experiment satellite (SORCE). These data will help to improve the representation of the solar forcing in the IPSL Global Circulation Model.

Total solar irradiance reconstruction since 1700 using a flux transport model

NASA Astrophysics Data System (ADS)

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

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

Aeronomic Impacts of a Revision to the Solar Irradiance Forcing for CMIP6

NASA Astrophysics Data System (ADS)

Marsh, D. R.; Chiodo, G.

2016-12-01

In preparation for the sixth phase of the Coupled Model Intercomparison Project (CMIP6), a revised solar forcing dataset has been the assembled as part of the Solar Influences activity of the Stratospheretroposphere Processes And their Role in Climate (SPARC) project. The new dataset differs significantly from the previous dataset used by CMIP5 models in the distribution of the mean solar spectral irradiance, particularly in the ultraviolet (UV). For example, in the 300 to 350 nm band the irradiance in the new model is reduced by approximately 0.7 Wm2. To put this in perspective, that change amounts to approximately 4 to 6 times the magnitude of the solar cycle variation in that band. Using the NCAR Whole Atmosphere Community Climate Model (WACCM), we assess the impact on stratospheric composition and dynamics of this revision to the solar irradiance by comparing WACCM experiments that are forced by either the CMIP5 or CMIP6 solar forcing dataset. We find that ozone in the middle stratosphere decreases by approximately 3% in the experiments forced with the CMIP6 dataset. At the stratopause ozone increases by over 1.6% in response to a 2% decrease in odd-hydrogen species (HOx = {H, OH and HO2} ) above 35 km. HOx reductions are caused by a decrease in the Hartley band irradiance that creates O(1D) from ozone photolysis; the reaction with O(1D) being the primary way in which H2O is converted to HOx. The reduction in UV irradiance in the CMIP6 forcing dataset also leads to a cooling of the stratosphere and lower mesosphere of up to 1.6K. Considering that smaller irradiance changes that occur over the solar cycle have been implicated in changes in surface climate, our study suggest that the mean state of climate models used in CMIP6 may be significantly different than those used in CMIP5, as a result of changes in the mean solar irradiance forcing.

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2012-01-01

NOAA's planned Total and Spectral Solar Irradiance Sensor (TSIS) mission will fly along with the NOAA user service payloads Advanced Data Collection System (ADCS) and Search and Rescue Satellite Aided Tracking (SARSAT). In ' order to guarantee continuity in the 33-year solar irradiance climate data record, TSIS must be launched in time to overlap with current on-orbit solar irradiance instruments. Currently TSIS is moving towards a launch rcadinss date of January 2015. TSIS provides for continuation of the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) ,currently onboard NASA's Solar Radiation and Climate Experiment (SORCE) platform, launched in January 2003. The difficulty of ensuring continuity has increased due to the launch failure of NASA's Glory mission with its improved TIM. Achieving the needed overlap must now rely on extending SORCE. and maintaining the TSIS schedule. TSIS is one component of a NASA-NOAA joint program (JPSS) planned to transition certain climate observations to operational mode. We summarize issues of continuity, improvements being made to the TIM and 81M sensors, and plans to provide for traceability of total and spectral irradiance measurements to ground-based cryogenic standards.

A reconstruction of solar irradiance using a flux transport model

NASA Astrophysics Data System (ADS)

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

2012-07-01

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

Extraterrestrial materials processing

NASA Technical Reports Server (NTRS)

Steurer, W. H.

1982-01-01

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

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

NASA Astrophysics Data System (ADS)

Dick, Steven J.

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.

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

NASA Astrophysics Data System (ADS)

Dick, S. J.

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.

Classification of extraterrestrial civilizations

NASA Astrophysics Data System (ADS)

Tang, Tong B.; Chang, Grace

1991-06-01

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

Multivariate Analysis of Solar Spectral Irradiance Measurements

NASA Technical Reports Server (NTRS)

Pilewskie, P.; Rabbette, M.

2001-01-01

Principal component analysis is used to characterize approximately 7000 downwelling solar irradiance spectra retrieved at the Southern Great Plains site during an Atmospheric Radiation Measurement (ARM) shortwave intensive operating period. This analysis technique has proven to be very effective in reducing a large set of variables into a much smaller set of independent variables while retaining the information content. It is used to determine the minimum number of parameters necessary to characterize atmospheric spectral irradiance or the dimensionality of atmospheric variability. It was found that well over 99% of the spectral information was contained in the first six mutually orthogonal linear combinations of the observed variables (flux at various wavelengths). Rotation of the principal components was effective in separating various components by their independent physical influences. The majority of the variability in the downwelling solar irradiance (380-1000 nm) was explained by the following fundamental atmospheric parameters (in order of their importance): cloud scattering, water vapor absorption, molecular scattering, and ozone absorption. In contrast to what has been proposed as a resolution to a clear-sky absorption anomaly, no unexpected gaseous absorption signature was found in any of the significant components.

A reference solar spectral irradiance for use in atmospheric modeling

NASA Technical Reports Server (NTRS)

1982-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2010-09-01

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

Solar Irradiance, Plage and SOHO UV Images

NASA Astrophysics Data System (ADS)

Lopresto, James C.; Manross, Kevin

1996-05-01

Calcium K and H alpha plage and sunspot area have been monitored using Big Bear Observatory images on the INTERNET since November of 1992. The purpose of the project is to determine the correlation of changing plage area and solar irradiance changes. We also monitor changes in the K2 spec- tral index provided daily from Sacramento Peak. With the recent launching of the SOHO satellite, we are able to monitor the plage in the He II 304 Angstroms UV image. This image is near the top of the chromosphere nar or just under the transition region. The images show limb brightening as expected. Since it is widely believed that short time scale changes in the UV may be the dominant cause for low amplitude solar irradiance changes, the comparison of the "plage" ara in these UV images to those in conventional visible images should prove instructive.

Traveling reference spectroradiometer for routine quality assurance of spectral solar ultraviolet irradiance measurements.

PubMed

Gröbner, Julian; Schreder, Josef; Kazadzis, Stelios; Bais, Alkiviadis F; Blumthaler, Mario; Görts, Peter; Tax, Rick; Koskela, Tapani; Seckmeyer, Gunther; Webb, Ann R; Rembges, Diana

2005-09-01

A transportable reference spectroradiometer for measuring spectral solar ultraviolet irradiance has been developed and validated. The expanded uncertainty of solar irradiance measurements with this reference spectroradiometer, based on the described methodology, is 8.8% to 4.6%, depending on the wavelength and the solar zenith angle. The accuracy of the spectroradiometer was validated by repeated site visits to two European UV monitoring sites as well as by regular comparisons with the reference spectroradiometer of the European Reference Centre for UV radiation measurements in Ispra, Italy. The spectral solar irradiance measurements of the Quality Assurance of Spectral Ultraviolet Measurements in Europe through the Development of a Transportable Unit (QASUME) spectroradiometer and these three spectroradiometers have agreed to better than 6% during the ten intercomparison campaigns held from 2002 to 2004. If the differences in irradiance scales of as much as 2% are taken into account, the agreement is of the order of 4% over the wavelength range of 300-400 nm.

Equivalence between solar irradiance and solar simulators in aging tests of sunglasses.

PubMed

Masili, Mauro; Ventura, Liliane

2016-08-26

This work is part of a broader research that focuses on ocular health. Three outlines are the basis of the pyramid that comprehend the research as a whole: authors' previous work, which has provided the public to self-check their own sunglasses regarding the ultraviolet protection compatible to their category; Brazilian national survey in order to improve nationalization of sunglasses standards; and studies conducted on revisiting requirements of worldwide sunglasses standards, in which this work is inserted. It is still controversial on the literature the ultraviolet (UV) radiation effects on the ocular media, but the World Health Organization has established safe limits on the exposure of eyes to UV radiation based on the studies reported in literature. Sunglasses play an important role in providing safety, and their lenses should provide adequate UV filters. Regarding UV protection for ocular media, the resistance-to-irradiance test for sunglasses under many national standards requires irradiating lenses for 50 uninterrupted hours with a 450 W solar simulator. This artificial aging test may provide a corresponding evaluation of exposure to the sun. Calculating the direct and diffuse solar irradiance at a vertical surface and the corresponding radiant exposure for the entire year, we compare the latter with the 50-h radiant exposure of a 450 W xenon arc lamp from a solar simulator required by national standards. Our calculations indicate that this stress test is ineffective in its present form. We provide evidence of the need to re-evaluate the parameters of the tests to establish appropriate safe limits for UV irradiance. This work is potentially significant for scientists and legislators in the field of sunglasses standards to improve the requirements of sunglasses quality and safety.

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

USGS Publications Warehouse

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

2000-01-01

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

Atmosphere, Ocean, Land, and Solar Irradiance Data Sets

NASA Technical Reports Server (NTRS)

Johnson, James; Ahmad, Suraiya

2003-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

The Sun varies over different timescales, from minutes to months, decades and millennia. Its variation is an important driver of terrestrial climate change and as such a significant input to climate models. While several observations exist to date over a broad frequency range, they are sparse over both frequency and time. As part of the SOLID (First European comprehensive SOlar Irradiance Data Exploitation) project we will show first results of constructing a homogeneous solar spectral irradiance data set of the UV. By combining a large variety of solar spectral irradiance data sets, we aim to reconstruct spectral solar variability further back in time and to deliver a data set that can be used by others, e.g. climate researchers in order to account for the non-constant solar forcing. We present the data used, together with preliminary internal uncertainty and error-estimates, self-consistent quality assessments, gap-filling methods and selection criteria. We use a combination of observed solar spectral irradiance from several missions, starting with OSO III in 1967, as well as available proxy data to identify outliers and trace them back to either instrumental or physical cause. The SOLID project is part of the seventh European framework programme. SOLID brings together representatives from all European solar space experiments and European teams specialized in irradiance modelling, reconstruction and solar image processing.

The New LASP Interactive Solar IRradiance Datacenter (LISIRD)

NASA Astrophysics Data System (ADS)

Baltzer, T.; Wilson, A.; Lindholm, D. M.; Snow, M. A.; Woodraska, D.; Pankratz, C. K.

2017-12-01

The New LASP Interactive Solar IRradiance Datacenter (LISIRD) The University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) has a long history of providing state of the art Solar instrumentation and datasets to the community. In 2005, LASP created a web interface called LISIRD which provided plotting of and access to a number of Solar Irradiance measured and modeled datasets, and it has been used extensively by members of the community both within and outside of LASP. In August of 2017, LASP is set to release a new version of LISIRD for use by anyone interested in viewing and downloading the datasets it serves. This talk will describe the new LISIRD with emphasis on features enabled by it to include: New and more functional plotting interfaces Better dataset browse and search capabilities More datasets Easier to add datasets from a wider array of resources Cleaner interface with better use of screen real estate Much easier to update metadata describing each dataset Much of this capability is leveraged off new infrastructure that will also be touched upon.

Recent Advancements in the Numerical Simulation of Surface Irradiance for Solar Energy Applications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Yu; Sengupta, Manajit; Deline, Chris

This paper briefly reviews the National Renewable Energy Laboratory's recent efforts on developing all-sky solar irradiance models for solar energy applications. The Fast All-sky Radiation Model for Solar applications (FARMS) utilizes the simulation of clear-sky transmittance and reflectance and a parameterization of cloud transmittance and reflectance to rapidly compute broadband irradiances on horizontal surfaces. FARMS delivers accuracy that is comparable to the two-stream approximation, but it is approximately 1,000 times faster. A FARMS-Narrowband Irradiance over Tilted surfaces (FARMS-NIT) has been developed to compute spectral irradiances on photovoltaic (PV) panels in 2002 wavelength bands. Further, FARMS-NIT has been extended for bifacialmore » PV panels.« less

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

NASA Technical Reports Server (NTRS)

Schlesinger, Barry M.; Heath, Donald F.

1988-01-01

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

Photo-recovery of electron-irradiated GaAs solar cells

NASA Technical Reports Server (NTRS)

Meulenberg, Andrew

1995-01-01

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

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials

PubMed Central

MacPherson, Glenn J.; Thiemens, Mark H.

2011-01-01

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

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

PubMed

MacPherson, Glenn J; Thiemens, Mark H

2011-11-29

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

Multi-objective Optimization of Solar Irradiance and Variance at Pertinent Inclination Angles

NASA Astrophysics Data System (ADS)

Jain, Dhanesh; Lalwani, Mahendra

2018-05-01

The performance of photovoltaic panel gets highly affected bychange in atmospheric conditions and angle of inclination. This article evaluates the optimum tilt angle and orientation angle (surface azimuth angle) for solar photovoltaic array in order to get maximum solar irradiance and to reduce variance of radiation at different sets or subsets of time periods. Non-linear regression and adaptive neural fuzzy interference system (ANFIS) methods are used for predicting the solar radiation. The results of ANFIS are more accurate in comparison to non-linear regression. These results are further used for evaluating the correlation and applied for estimating the optimum combination of tilt angle and orientation angle with the help of general algebraic modelling system and multi-objective genetic algorithm. The hourly average solar irradiation is calculated at different combinations of tilt angle and orientation angle with the help of horizontal surface radiation data of Jodhpur (Rajasthan, India). The hourly average solar irradiance is calculated for three cases: zero variance, with actual variance and with double variance at different time scenarios. It is concluded that monthly collected solar radiation produces better result as compared to bimonthly, seasonally, half-yearly and yearly collected solar radiation. The profit obtained for monthly varying angle has 4.6% more with zero variance and 3.8% more with actual variance, than the annually fixed angle.

The Development of Politics in Extraterrestrial Colonies

NASA Astrophysics Data System (ADS)

Sivier, D. J.

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

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

NASA Astrophysics Data System (ADS)

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

2014-11-01

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

Panel Discussions on Total Solar Irradiance Variations and the Maunder Minimum

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Analysis of Cumulus Solar Irradiance Reflectance (CSIR) Events

NASA Technical Reports Server (NTRS)

Laird, John L.; Harshvardham

1996-01-01

Clouds are extremely important with regard to the transfer of solar radiation at the earth's surface. This study investigates Cumulus Solar Irradiance Reflection (CSIR) using ground-based pyranometers. CSIR events are short-term increases in solar radiation observed at the surface as a result of reflection off the sides of convective clouds. When sun-cloud observer geometry is favorable, these occurrences produce characteristic spikes in the pyranometer traces and solar irradiance values may exceed expected clear-sky values. Ultraviolet CSIR events were investigated during the summer of 1995 using Yankee Environmental Systems UVA-1 and UVB-1 pyranometers. Observed data were compared to clear-sky curves which were generated using a third degree polynomial best-fit line technique. Periods during which the observed data exceeded this clear-sky curve were identified as CSIR events. The magnitude of a CSIR event was determined by two different quantitative calculations. The MAC (magnitude above clear-sky) is an absolute measure of the difference between the observed and clear-sky irradiances. Maximum MAC values of 3.4 Wm(exp -2) and 0.069 Wm(exp -2) were observed at the UV-A and UV-B wavelengths, respectively. The second calculation determined the percentage above clear-sky (PAC) which indicated the relative magnitude of a CSIR event. Maximum UV-A and UV-B PAC magnitudes of 10.1% and 7.8%, respectively, were observed during the study. Also of interest was the duration of the CSIR events which is a function of sun-cloud-sensor geometry and the speed of cloud propagation over the measuring site. In both the UV-A and UV-B wavelengths, significant CSIR durations of up to 30 minutes were observed.

Solar Irradiance Variability and Its Impacts on the Earth Climate System

NASA Astrophysics Data System (ADS)

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

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

Recent solar extreme ultraviolet irradiance observations and modeling: A review

NASA Technical Reports Server (NTRS)

Tobiska, W. Kent

1993-01-01

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

Solar UV-B irradiance and total ozone in Italy: Fluctuations and trends

NASA Astrophysics Data System (ADS)

Casale, G. R.; Meloni, D.; Miano, S.; Palmieri, S.; Siani, A. M.; Cappellani, F.

2000-02-01

Solar UV irradiance spectra (290-325 nm) together with daily total ozone column observations have been collected since 1992 by means of Brewer spectrophotometers at two Italian stations (Rome and Ispra). The available Brewer irradiance data, recorded around noon and at fixed solar zenith angles, together with the output of a radiative transfer model (the STAR model) are presented and analyzed. The Brewer irradiance measurements and total ozone fluctuations and anomalies are investigated, pointing out the correlation between the high-frequency O3 components and irradiance at 305 nm. In addition, the total ozone long time series of Arosa (170 km apart from Ispra) and Vigna di Valle (very close to Rome) are analyzed to illustrate evidence of temporal variations and a possible trend.

Recent changes in solar irradiance and infrared irradiance related with air temperature and cloudiness at the King Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Jung, Y.; Kim, J.; Cho, H.; Lee, B.

2006-12-01

The polar region play a critical role in the surface energy balance and the climate system of the Earth. The important question in the region is that what is the role of the Antarctic atmospheric heat sink of global climate. Thus, this study shows the trends of global solar irradiance, infrared irradiance, air temperature and cloudiness measured at the King Sejong station, Antarctica, during the period of 1996-2004 and determines their relationship and variability of the surface energy balance. Annual average of solar radiation and cloudiness is 81.8 Wm-2 and 6.8 oktas and their trends show the decrease of -0.24 Wm-2yr-1(-0.30 %yr-1) and 0.02 oktas yr-1(0.30 %yr-1). The change of solar irradiance is directly related to change of cloudiness and decrease of solar irradiance presents radiative cooling at the surface. Monthly mean infrared irradiance, air temperature and specific humidity shows the decrease of -2.11 Wm^{- 2}yr-1(-0.75 %yr-1), -0.07 'Cyr-1(-5.15 %yr-1) and -0.044 gkg-1yr-1(-1.42 %yr-1), respectively. Annual average of the infrared irradiance is 279.9 Wm-2 and correlated with the air temperature, specific humidity and cloudiness. A multiple regression model for estimation of the infrared irradiance using the components has been developed. Effects of the components on the infrared irradiance changes show 52 %, 19 % and 10 % for air temperature, specific humidity and cloudiness, respectively. Among the components, air temperature has a great influence on infrared irradiance. Despite the increase of cloudiness, the decrease in the infrared irradiance is due to the decrease of air temperature and specific humidity which have a cooling effect. Therefore, the net radiation of the surface energy balance shows radiative cooling of negative 11-24 Wm^{- 2} during winter and radiative warming of positive 32-83 Wm-2 during the summer. Thus, the amount of shortage and surplus at the surface is mostly balanced by turbulent flux of sensible and latent heat.

Reconstruction of total solar irradiance 1974-2009

NASA Astrophysics Data System (ADS)

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

2012-05-01

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.

The Impact of Different Absolute Solar Irradiance Values on Current Climate Model Simulations

NASA Technical Reports Server (NTRS)

Rind, David H.; Lean, Judith L.; Jonas, Jeffrey

2014-01-01

Simulations of the preindustrial and doubled CO2 climates are made with the GISS Global Climate Middle Atmosphere Model 3 using two different estimates of the absolute solar irradiance value: a higher value measured by solar radiometers in the 1990s and a lower value measured recently by the Solar Radiation and Climate Experiment. Each of the model simulations is adjusted to achieve global energy balance; without this adjustment the difference in irradiance produces a global temperature change of 0.48C, comparable to the cooling estimated for the Maunder Minimum. The results indicate that by altering cloud cover the model properly compensates for the different absolute solar irradiance values on a global level when simulating both preindustrial and doubled CO2 climates. On a regional level, the preindustrial climate simulations and the patterns of change with doubled CO2 concentrations are again remarkably similar, but there are some differences. Using a higher absolute solar irradiance value and the requisite cloud cover affects the model's depictions of high-latitude surface air temperature, sea level pressure, and stratospheric ozone, as well as tropical precipitation. In the climate change experiments it leads to an underestimation of North Atlantic warming, reduced precipitation in the tropical western Pacific, and smaller total ozone growth at high northern latitudes. Although significant, these differences are typically modest compared with the magnitude of the regional changes expected for doubled greenhouse gas concentrations. Nevertheless, the model simulations demonstrate that achieving the highest possible fidelity when simulating regional climate change requires that climate models use as input the most accurate (lower) solar irradiance value.

Searching for extra-terrestrial civilizations

NASA Technical Reports Server (NTRS)

Gindilis, L. M.

1974-01-01

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

Search for extraterrestrial intelligence (SETI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrison, P.; Billingham, J.; Wolfe, J.

1977-01-01

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

Annealing characteristics of irradiated hydrogenated amorphous silicon solar cells

NASA Technical Reports Server (NTRS)

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

1991-01-01

It was shown that 1 MeV proton irradiation with fluences of 1.25E14 and 1.25E15/sq cm reduces the normalized I(sub SC) of a-Si:H solar cell. Solar cells recently fabricated showed superior radiation tolerance compared with cells fabricated four years ago; the improvement is probably due to the fact that the new cells are thinner and fabricated from improved materials. Room temperature annealing was observed for the first time in both new and old cells. New cells anneal at a faster rate than old cells for the same fluence. From the annealing work it is apparent that there are at least two types of defects and/or annealing mechanisms. One cell had improved I-V characteristics following irradiation as compared to the virgin cell. The work shows that the photothermal deflection spectroscopy (PDS) and annealing measurements may be used to predict the qualitative behavior of a-Si:H solar cells. It was anticipated that the modeling work will quantitatively link thin film measurements with solar cell properties. Quantitative predictions of the operation of a-Si:H solar cells in a space environment will require a knowledge of the defect creation mechanisms, defect structures, role of defects on degradation, and defect passivation and annealing mechanisms. The engineering data and knowledge base for justifying space flight testing of a-Si:H alloy based solar cells is being developed.

The Variability of Solar Spectral Irradiance and Solar Surface Indices Through the Solar Activity Cycles 21-23

NASA Astrophysics Data System (ADS)

Deniz Goker, Umit

2016-07-01

A study of variations of solar spectral irradiance (SSI) in the wavelength ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We developed a special software for extracting the data and reduced this data by using the MATLAB. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) emission lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar cycles (SCs) 23 and 24. We also compared our results with the ground-based telescopes as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal Data (KKL) and NGDC Homepage (Rome and Learmonth Solar Observatories). We studied the variations of total solar irradiance (TSI), magnetic field, sunspots/sunspot groups, Ca II K-flux, faculae and plage areas data with these ground-based telescopes, respectively. We reduced the selected data using the Phyton programming language and plot with the IDL programme. Therefore, we found that there was a decrease in the area of bright faculae and chromospheric plages while the percentage of dark faculae and plage decrease, as well. However, these decreases mainly occurred in small sunspots, contrary to this, these terms in large sunspot groups were comparable to previous SCs or even larger. Nevertheless, negative correlations between ISSN and SSI data indicate that these emissions are in close connection with the classes of sunspots/sunspot groups and "PLAGE" regions. Finally, we applied the time series of the chemical elements correspond to the wavelengths 121.5 nm-300.5 nm and compared with the ISSN data. We found an unexpected increasing in the 298.5 nm for the Fe II element. The variability of Fe II (298.5 nm) is in close connection with the plage regions and the sizes of the

The origin of Total Solar Irradiance variability on timescales less than a day

NASA Astrophysics Data System (ADS)

Shapiro, Alexander; Krivova, Natalie; Schmutz, Werner; Solanki, Sami K.; Leng Yeo, Kok; Cameron, Robert; Beeck, Benjamin

2016-07-01

Total Solar Irradiance (TSI) varies on timescales from minutes to decades. It is generally accepted that variability on timescales of a day and longer is dominated by solar surface magnetic fields. For shorter time scales, several additional sources of variability have been proposed, including convection and oscillation. However, available simplified and highly parameterised models could not accurately explain the observed variability in high-cadence TSI records. We employed the high-cadence solar imagery from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and the SATIRE (Spectral And Total Irradiance Reconstruction) model of solar irradiance variability to recreate the magnetic component of TSI variability. The recent 3D simulations of solar near-surface convection with MURAM code have been used to calculate the TSI variability caused by convection. This allowed us to determine the threshold timescale between TSI variability caused by the magnetic field and convection. Our model successfully replicates the TSI measurements by the PICARD/PREMOS radiometer which span the period of July 2010 to February 2014 at 2-minute cadence. Hence, we demonstrate that solar magnetism and convection can account for TSI variability at all timescale it has ever been measured (sans the 5-minute component from p-modes).

IR Spectroscopy and Photo-Chemistry of Extraterrestrial Ices

NASA Technical Reports Server (NTRS)

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

2005-01-01

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

Space transportation and destination considerations for extraterrestrial disposal of radioactive waste

NASA Technical Reports Server (NTRS)

Zimmerman, A. V.; Thompson, R. L.; Lubick, R. J.

1973-01-01

A feasibility study is summarized of extraterrestrial (space) disposal of radioactive waste. The initial work on the evaluation and comparison of possible space destinations and launch vehicles is reported. Only current or planned space transportation systems were considered. The currently planned space shuttle was found to be more cost effective than current expendable launch vehicles, by about a factor of two. The space shuttle will require a third stage to perform the disposal missions. Depending on the particular mission this could be either a reusable space tug or an expendable stage such as a Centaur. Of the destinations considered, high earth orbits (between geostationary and lunar orbit altitudes), solar orbits (such as a 0.90 AU circular solar orbit) or a direct injection to solar system escape appear to be the best candidates. Both earth orbits and solar orbits have uncertainties regarding orbit stability and waste package integrity for times on the order of a million years.

Laboratory for Extraterrestrial Physics

NASA Technical Reports Server (NTRS)

Vondrak, Richard R. (Technical Monitor)

2001-01-01

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

Irradiance optimization of outdoor microalgal cultures using solar tracked photobioreactors.

PubMed

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

2013-03-01

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 μmol 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 μmol 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.

[An encounter with extraterrestrial intelligence].

PubMed

Hisabayashi, Hisashi

2003-12-01

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.

Nonimaging solar concentrator with near-uniform irradiance for photovoltaic arrays

NASA Astrophysics Data System (ADS)

O'Gallagher, Joseph J.; Winston, Roland; Gee, Randy

2001-11-01

We report results of a study our group has undertaken to design a solar concentrator with uniform irradiance on a planar target. This attribute is especially important for photovoltaic concentrators. We find that a variety of optical mixers, some incorporating a moderate level of concentration, can be quite effective in achieving near uniform irradiance.

Extraterrestrial civilizations: Problems of their evolution

NASA Technical Reports Server (NTRS)

Leskov, L. V.

1987-01-01

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

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

NASA Astrophysics Data System (ADS)

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

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

Possible external sources of terrestrial cloud cover variability: the solar wind

NASA Astrophysics Data System (ADS)

Voiculescu, Mirela; Usoskin, Ilya; Condurache-Bota, Simona

2014-05-01

Cloud cover plays an important role in the terrestrial radiation budget. The possible influence of the solar activity on cloud cover is still an open question with contradictory answers. An extraterrestrial factor potentially affecting the cloud cover is related to fields associated with solar wind. We focus here on a derived quantity, the interplanetary electric field (IEF), defined as the product between the solar wind speed and the meridional component, Bz, of the interplanetary magnetic field (IMF) in the Geocentric Solar Magnetospheric (GSM) system. We show that cloud cover at mid-high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Since the IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others. We also present results showing that the link between cloud cover and IMF varies depending on composition and altitude of clouds.

How calibration and reference spectra affect the accuracy of absolute soft X-ray solar irradiance measured by the SDO/EVE/ESP during high solar activity

NASA Astrophysics Data System (ADS)

Didkovsky, Leonid; Wieman, Seth; Woods, Thomas

2016-10-01

The Extreme ultraviolet Spectrophotometer (ESP), one of the channels of SDO's Extreme ultraviolet Variability Experiment (EVE), measures solar irradiance in several EUV and soft x-ray (SXR) bands isolated using thin-film filters and a transmission diffraction grating, and includes a quad-diode detector positioned at the grating zeroth-order to observe in a wavelength band from about 0.1 to 7.0 nm. The quad diode signal also includes some contribution from shorter wavelength in the grating's first-order and the ratio of zeroth-order to first-order signal depends on both source geometry, and spectral distribution. For example, radiometric calibration of the ESP zeroth-order at the NIST SURF BL-2 with a near-parallel beam provides a different zeroth-to-first-order ratio than modeled for solar observations. The relative influence of "uncalibrated" first-order irradiance during solar observations is a function of the solar spectral irradiance and the locations of large Active Regions or solar flares. We discuss how the "uncalibrated" first-order "solar" component and the use of variable solar reference spectra affect determination of absolute SXR irradiance which currently may be significantly overestimated during high solar activity.

Solar light irradiation significantly reduced cytotoxicity and disinfection byproducts in chlorinated reclaimed water.

PubMed

Lv, Xiao-Tong; Zhang, Xue; Du, Ye; Wu, Qian-Yuan; Lu, Yun; Hu, Hong-Ying

2017-11-15

Chlorinated reclaimed water is widely used for landscaping and recreational purposes, resulting in human exposure to toxic disinfection byproducts. Although the quality of chlorinated reclaimed water might be affected by sunlight during storage, the effects of solar light irradiation on the toxicity remain unknown. This study investigated the changes in cytotoxicity and total organic halogen (TOX) of chlorinated reclaimed water exposed to solar light. Irradiation with solar light for 12 h was found to significantly reduce the cytotoxicity of chlorinated reclaimed water by about 75%, with ultraviolet light being responsible for the majority of this reduction. Chlorine residual in reclaimed water tended to increase the cytotoxicity, and the synergy between solar light and free chlorine could not enhance the reduction of cytotoxicity. Adding hydroxyl radical scavengers revealed that the contribution of hydroxyl radical to cytotoxicity reduction was limited. Solar light irradiation concurrently reduced TOX. The low molecular weight (<1 kDa) fraction was the major contributor of cytotoxicity and TOX in chlorinated reclaimed water. Detoxification of the low molecular weight fraction by light irradiation was mainly a result of TOX dehalogenation, while detoxification of the high molecular weight (>1 kDa) fraction was probably caused by photoconversion from high toxic TOX to low toxic TOX. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Kiang, Richard K.; Kyle, H. Lee

2000-01-01

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

A novel procedure for generating solar irradiance TSYs

NASA Astrophysics Data System (ADS)

Fanego, Vicente Lara; Rubio, Jesús Pulgar; Peruchena, Carlos M. Fernández; Romeo, Martín Gastón; Tejera, Sara Moreno; Santigosa, Lourdes Ramírez; Balderrama, Rita X. Valenzuela; Tirado, Luis F. Zarzalejo; Pantaleón, Diego Bermejo; Pérez, Manuel Silva; Contreras, Manuel Pavón; García, Ana Bernardos; Anarte, Sergio Macías

2017-06-01

Typical Solar Years (TSYs) are key parameters for the solar energy industry. In particular, TSYs are mainly used for the design and bankability analysis of solar projects. In essence, a TSY intends to describe the expected long-term behavior of the solar resource (direct and/or global irradiance) into a condensed period of one year at the specific location of interest. A TSY differs from a conventional Typical Meteorological Year (TMY) by its absence of meteorological variables other than solar radiation. Concerning the probability of exceedance (Pe) needed for bankability, various scenarios are commonly used, with Pe90, Pe95 or even Pe99 being most usually required as unfavorable scenarios, along with the most widely used median scenario (Pe50). There is no consensus in the scientific community regarding the methodology for generating TSYs for any Pe scenario. Furthermore, the application of two different construction methods to the same original dataset could produce differing TSYs. Within this framework, a group of experts has been established by the Spanish Association for Standardization and Certification (AENOR) in order to propose a method that can be standardized. The method developed by this working group, referred to as the EVA method, is presented in this contribution. Its evaluation shows that it provides reasonable results for the two main irradiance components (direct and global), with low errors in the annual estimations for any given Pe. The EVA method also preserves the long-term statistics when the computed TSYs for a specific Pe are expanded from the monthly basis used in the generation of the TSY to higher time resolutions, such as 1 hour, which are necessary for the precise energy simulation of solar systems.

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

NASA Astrophysics Data System (ADS)

Ortegón Gallego, A.

2010-09-01

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

Influence of spatiotemporally distributed irradiance data input on temperature evolution in parabolic trough solar field simulations

NASA Astrophysics Data System (ADS)

Bubolz, K.; Schenk, H.; Hirsch, T.

2016-05-01

Concentrating solar field operation is affected by shadowing through cloud movement. For line focusing systems the impact of varying irradiance has been studied before by several authors with simulations of relevant thermodynamics assuming spatially homogeneous irradiance or using artificial test signals. While today's simulation capabilities allow more and more a higher spatiotemporal resolution of plant processes there are only few studies on influence of spatially distributed irradiance due to lack of available data. Based on recent work on generating real irradiance maps with high spatial resolution this paper demonstrates their influence on solar field thermodynamics. For a case study an irradiance time series is chosen. One solar field section with several loops and collecting header is modeled for simulation purpose of parabolic trough collectors and oil as heat transfer medium. Assuming homogeneous mass flow distribution among all loops we observe spatially varying temperature characteristics. They are analysed without and with mass flow control and their impact on solar field control design is discussed. Finally, the potential of distributed irradiance data is outlined.

Smartphone-Based Android app for Determining UVA Aerosol Optical Depth and Direct Solar Irradiances.

PubMed

Igoe, Damien P; Parisi, Alfio; Carter, Brad

2014-01-01

This research describes the development and evaluation of the accuracy and precision of an Android app specifically designed, written and installed on a smartphone for detecting and quantifying incident solar UVA radiation and subsequently, aerosol optical depth at 340 and 380 nm. Earlier studies demonstrated that a smartphone image sensor can detect UVA radiation and the responsivity can be calibrated to measured direct solar irradiance. This current research provides the data collection, calibration, processing, calculations and display all on a smartphone. A very strong coefficient of determination of 0.98 was achieved when the digital response was recalibrated and compared to the Microtops sun photometer direct UVA irradiance observations. The mean percentage discrepancy for derived direct solar irradiance was only 4% and 6% for observations at 380 and 340 nm, respectively, lessening with decreasing solar zenith angle. An 8% mean percent difference discrepancy was observed when comparing aerosol optical depth, also decreasing as solar zenith angle decreases. The results indicate that a specifically designed Android app linking and using a smartphone image sensor, calendar and clock, with additional external narrow bandpass and neutral density filters can be used as a field sensor to evaluate both direct solar UVA irradiance and low aerosol optical depths for areas with low aerosol loads. © 2013 The American Society of Photobiology.

Searching for extraterrestrial civilizations.

PubMed

Kuiper, T B; Morris, M

1977-05-06

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

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

NASA Technical Reports Server (NTRS)

Bailey, Scott Martin

1995-01-01

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

Extraterrestrial imperative

NASA Technical Reports Server (NTRS)

Ehricke, K. A.

1972-01-01

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

The effects of sunspots on solar irradiance

NASA Technical Reports Server (NTRS)

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

1982-01-01

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

Optical search for extraterrestrial intelligence with Air Cerenkov telescopes.

PubMed

Eichler, D; Beskin, G

2001-01-01

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.

Volcanic ash - Terrestrial versus extraterrestrial

NASA Technical Reports Server (NTRS)

Okeefe, J. A.

1976-01-01

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

Modelling of electric characteristics of 150-watt peak solar panel using Boltzmann sigmoid function under various temperature and irradiance

NASA Astrophysics Data System (ADS)

Sapteka, A. A. N. G.; Narottama, A. A. N. M.; Winarta, A.; Amerta Yasa, K.; Priambodo, P. S.; Putra, N.

2018-01-01

Solar energy utilized with solar panel is a renewable energy that needs to be studied further. The site nearest to the equator, it is not surprising, receives the highest solar energy. In this paper, a modelling of electrical characteristics of 150-Watt peak solar panels using Boltzmann sigmoid function under various temperature and irradiance is reported. Current, voltage, temperature and irradiance data in Denpasar, a city located at just south of equator, was collected. Solar power meter is used to measure irradiance level, meanwhile digital thermometer is used to measure temperature of front and back panels. Short circuit current and open circuit voltage data was also collected at different temperature and irradiance level. Statistically, the electrical characteristics of 150-Watt peak solar panel can be modelled using Boltzmann sigmoid function with good fit. Therefore, it can be concluded that Boltzmann sigmoid function might be used to determine current and voltage characteristics of 150-Watt peak solar panel under various temperature and irradiance.

Decomposition Behavior of Curcumin during Solar Irradiation when Contact with Inorganic Particles

NASA Astrophysics Data System (ADS)

Nandiyanto, A. B. D.; Wiryani, A. S.; Rusli, A.; Purnamasari, A.; Abdullah, A. G.; Riza, L. S.

2017-03-01

Curcumin is one of materials which have been widely used in medicine, Asian cuisine, and traditional cosmetic. Therefore, understanding the stability of curcumin has been widely studied. The purpose of this study was to investigate the stability of curcumin solution against solar irradiation when making contact with inorganic material. As a model for the inorganic material, titanium dioxide (TiO2) was used. In the experimental method, the curcumin solution was irradiated using a solar irradiation. To confirm the stability of curcumin when contact with inorganic material, we added TiO2 micro particles with different concentrations. The results showed that the concentration of curcumin decreased during solar irradiation. The less concentration of curcumin affected the more decomposition rate obtained. The decomposition rate was increased greatly when TiO2 was added, in which the more TiO2 concentration added allowed the faster decomposition rate. Based on the result, we conclude that the curcumin is relatively stable as long as using higher concentration of curcumin and is no inorganic material existed. Then, the decomposition can be minimized by avoiding contact with inorganic material.

Universalist ethics in extraterrestrial encounter

NASA Astrophysics Data System (ADS)

Baum, Seth D.

2010-02-01

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.

Advanced Curation of Current and Future Extraterrestrial Samples

NASA Technical Reports Server (NTRS)

Allen, Carlton C.

2013-01-01

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. Curation includes documentation, preservation, preparation, and distribution of samples. The current collections of extraterrestrial samples include: Lunar rocks / soils collected by the Apollo astronauts Meteorites, including samples of asteroids, the Moon, and Mars "Cosmic dust" (asteroid and comet particles) collected by high-altitude aircraft Solar wind atoms collected by the Genesis spacecraft Comet particles collected by the Stardust spacecraft Interstellar dust collected by the Stardust spacecraft Asteroid particles collected by the Hayabusa spacecraft These samples were formed in environments strikingly different from that on Earth. Terrestrial contamination can destroy much of the scientific significance of many extraterrestrial materials. In order to preserve the research value of these precious samples, contamination must be minimized, understood, and documented. In addition the samples must be preserved - as far as possible - from physical and chemical alteration. In 2011 NASA selected the OSIRIS-REx mission, designed to return samples from the primitive asteroid 1999 RQ36 (Bennu). JAXA will sample C-class asteroid 1999 JU3 with the Hayabusa-2 mission. ESA is considering the near-Earth asteroid sample return mission Marco Polo-R. The Decadal Survey listed the first lander in a Mars sample return campaign as its highest priority flagship-class mission, with sample return from the South Pole-Aitken basin and the surface of a comet among additional top priorities. The latest NASA budget proposal includes a mission to capture a 5-10 m asteroid and return it to the vicinity of the Moon as a target for future sampling. Samples, tools, containers, and contamination witness materials from any of these missions carry unique requirements for acquisition and curation. Some of these requirements represent significant advances over

Curating NASA's Extraterrestrial Samples - Past, Present, and Future

NASA Technical Reports Server (NTRS)

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

2011-01-01

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. The Astromaterials Acquisition and Curation Office at the NASA Johnson Space Center (JSC) is responsible for curating NASA s extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10E "Curation of Extraterrestrial Materials", JSC is charged with ". . . curation of all extraterrestrial material under NASA control, including future NASA missions." The Directive goes on to define Curation as including "documentation, preservation, preparation, and distribution of samples for research, education, and public outreach."

Curating NASA's Extraterrestrial Samples - Past, Present, and Future

NASA Technical Reports Server (NTRS)

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

2010-01-01

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. The Astromaterials Acquisition and Curation Office at the NASA Johnson Space Center (JSC) is responsible for curating NASA's extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10E "Curation of Extraterrestrial Materials," JSC is charged with ". . . curation of all extraterrestrial material under NASA control, including future NASA missions." The Directive goes on to define Curation as including documentation, preservation, preparation, and distribution of samples for research, education, and public outreach.

Deployment and early results from the CanSIM (Canadian Solar Spectral Irradiance Meter) network

NASA Astrophysics Data System (ADS)

Tatsiankou, Viktar; Hinzer, Karin; Schriemer, Henry; McVey-White, Patrick; Beal, Richard

2017-09-01

Three of seven stations have been deployed as part of the Canadian Solar Spectral Irradiance (CanSIM) network situated in Ottawa, Varennes and Egbert to measure long term spectral variation of the direct normal (DNI) and global horizontal irradiances (GHI) across the country. Every station is equipped with a solar tracker, SolarSIM-D2+, SolarSIM-G+, and SR20 pyranometer, reporting the spectral DNI, GHI, diffuse horizontal irradiance (DHI) and aerosol optical depth in the 280-4000 nm range, broadband DNI, GHI, and DHI, atmospheric total column ozone and water vapour amounts. The spectral GHI as measured by the SolarSIM-G+ was within 5% as compared to EKO MS-700 spectroradiometer in 350-1050 nm range on 17 March 2017. The difference in the GHI as reported by SolarSIM-G+ and SR20 pyranometer from all stations was within 2% on 14 April 2017. Furthermore, on this day, the daily GHI sum for the Ottawa, Varennes, and Egbert stations was 7.01, 6.95, and 7.11 kWh/m2, respectively, while the daily DNI sum was 10.65, 10.86, 10.04 kWh/m2, respectively.

Instruments and methods to search for extraterrestrial life

NASA Astrophysics Data System (ADS)

Hoover, Richard B.

2015-09-01

Is Life restricted to the Planet Earth? or Does life exist elsewhere in the Cosmos? The existence of extraterrestrial life is the fundamental question of Astrobiology. Detecting evidence for living organisms beyond our planet is even more difficult than finding fossilized remains of ancient organisms. Microbiological investigations during the past century have established the fundamental physical and chemical requirements and limits for life on Earth. It is now known that life requires only water, a source of energy, and a small suite of biogenic elements under a surprisingly wide range of environmental conditions. The discovery that microbial extremophiles live and grow over a very broad span of temperature, pH, salinity, pressure and radiation levels has greatly enhanced the possibility that life may be present on many bodies of our Solar System. Recent discoveries by Space Missions and Rovers have invalidated many long held paradigms regarding the distribution of water, organic chemicals and the possibility of life elsewhere in the Cosmos. This paper considers the discovery of water, ice and organics on distant planets, moons and comets and evidence for fossil organisms on Mars and in SNC and carbonaceous meteorites. Instruments and methods are considered for spectroscopy and fluorescence of biomolecules (e.g., photosynthetic pigments) for remote detection of conclusive evidence for extraterrestrial life. Optical Video Microscopy is discussed as a direct means for detecting extraterrestrial life using small visible light/UV video microscopes, with ample magnification to record motile bacteria and other living organisms in samples collected by Rovers or Landers. Locomotion of living cells of bacteria and other microbes requires great expenditure of energy and motile cells can be distinguished by video microscopy from the physico-chemical movements (by Brownian Motion, Diffusion or Current Drift) of dead cells, dust particles and abiotic mineral grains.

PELS (Planetary Environmental Liquid Simulator): a new type of simulation facility to study extraterrestrial aqueous environments.

PubMed

Martin, Derek; Cockell, Charles S

2015-02-01

Investigations of other planetary bodies, including Mars and icy moons such as Enceladus and Europa, show that they may have hosted aqueous environments in the past and may do so even today. Therefore, a major challenge in astrobiology is to build facilities that will allow us to study the geochemistry and habitability of these extraterrestrial environments. Here, we describe a simulation facility (PELS: Planetary Environmental Liquid Simulator) with the capability for liquid input and output that allows for the study of such environments. The facility, containing six separate sample vessels, allows for statistical replication of samples. Control of pressure, gas composition, UV irradiation conditions, and temperature allows for the precise replication of aqueous conditions, including subzero brines under martian atmospheric conditions. A sample acquisition system allows for the collection of both liquid and solid samples from within the chamber without breaking the atmospheric conditions, enabling detailed studies of the geochemical evolution and habitability of past and present extraterrestrial environments. The facility we describe represents a new frontier in planetary simulation-continuous flow-through simulation of extraterrestrial aqueous environments.

Detection of Extraterrestrial Ecology (Exoecology)

NASA Technical Reports Server (NTRS)

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

2000-01-01

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

The recognition of extraterrestrial artificial signals

NASA Technical Reports Server (NTRS)

Seeger, C. L.

1980-01-01

Considerations in the design of receivers for the detection and recognition of artificial microwave signals of extraterrestrial origin are discussed. Following a review of the objectives of SETI and the probable reception and detection characteristics of extraterrestrial signals, means for the improvement of the sensitivity, signal-to-noise ratios and on-line data processing capabilities of SETI receivers are indicated. The characteristics of the signals likely to be present at the output of an ultra-low-noise microwave receiver are then examined, including the system background noise, terrestrial radiations, astrophysical radiations, accidental artificial radiations of terrestrial origin, and intentional radiations produced by humans and by extraterrestrial intelligence. The classes of extraterrestrial signals likely to be detected, beacons and leakage signals, are considered, and options in the specification of gating and thresholding for a high-spectral resolution, high-time-resolution signal discriminator are indicated. Possible tests for the nonhuman origin of a received signal are also pointed out.

Nuclear power--key to man's extraterrestrial civilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angelo, J.A.; Buden, D.

1982-08-01

The start of the Third Millennium will be highlighted by the establishment of man's extraterrestrial civilization with three technical cornerstones leading to the off-planet expansion of the human resource base. These are the availability of compact energy sources for power and propulsion, the creation of permanent manned habitats in space, and the ability to process materials anywhere in the Solar 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 powermore » plant technologies are discussed, with emphasis on derivatives from the nuclear rocket technology.« less

Variability in solar irradiance observed at two contrasting Antarctic sites

NASA Astrophysics Data System (ADS)

Petkov, Boyan H.; Láska, Kamil; Vitale, Vito; Lanconelli, Christian; Lupi, Angelo; Mazzola, Mauro; Budíková, Marie

2016-05-01

The features of erythemally weighted (EW) and short-wave downwelling (SWD) solar irradiances, observed during the spring-summer months of 2007-2011 at Johann Gregor Mendel (63°48‧S, 57°53‧W, 7 m a.s.l.) and Dome Concordia (75°06‧S, 123°21‧E, 3233 m a.s.l.) stations, placed at the Antarctic coastal region and on the interior plateau respectively, have been analysed and compared to each other. The EW and SWD spectral components have been presented by the corresponding daily integrated values and were examined taking into account the different geographic positions and different environmental conditions at both sites. The results indicate that at Mendel station the surface solar irradiance is strongly affected by the changes in the cloud cover, aerosols and albedo that cause a decrease in EW between 20% and 35%, and from 0% to 50% in SWD component, which contributions are slightly lower than the seasonal SWD variations evaluated to be about 71%. On the contrary, the changes in the cloud cover features at Concordia station produce only a 5% reduction of the solar irradiance, whilst the seasonal oscillations of 94% turn out to be the predominant mode. The present analysis leads to the conclusion that the variations in the ozone column cause an average decrease of about 46% in EW irradiance with respect to the value found in the case of minimum ozone content at each of the stations. In addition, the ratio between EW and SWD spectral components can be used to achieve a realistic assessment of the radiation amplification factor that quantifies the relationship between the atmospheric ozone and the surface UV irradiance.

Worldwide multi-model intercomparison of clear-sky solar irradiance predictions

NASA Astrophysics Data System (ADS)

Ruiz-Arias, Jose A.; Gueymard, Christian A.; Cebecauer, Tomas

2017-06-01

Accurate modeling of solar radiation in the absence of clouds is highly important because solar power production peaks during cloud-free situations. The conventional validation approach of clear-sky solar radiation models relies on the comparison between model predictions and ground observations. Therefore, this approach is limited to locations with availability of high-quality ground observations, which are scarce worldwide. As a consequence, many areas of in-terest for, e.g., solar energy development, still remain sub-validated. Here, a worldwide inter-comparison of the global horizontal irradiance (GHI) and direct normal irradiance (DNI) calculated by a number of appropriate clear-sky solar ra-diation models is proposed, without direct intervention of any weather or solar radiation ground-based observations. The model inputs are all gathered from atmospheric reanalyses covering the globe. The model predictions are compared to each other and only their relative disagreements are quantified. The largest differences between model predictions are found over central and northern Africa, the Middle East, and all over Asia. This coincides with areas of high aerosol optical depth and highly varying aerosol distribution size. Overall, the differences in modeled DNI are found about twice larger than for GHI. It is argued that the prevailing weather regimes (most importantly, aerosol conditions) over regions exhibiting substantial divergences are not adequately parameterized by all models. Further validation and scrutiny using conventional methods based on ground observations should be pursued in priority over those specific regions to correctly evaluate the performance of clear-sky models, and select those that can be recommended for solar concentrating applications in particular.

Searching for extraterrestrial civilizations

NASA Technical Reports Server (NTRS)

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

1977-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1997-01-01

The NOAA-9 SBEV/2 instrument has made the first regular measurements ot solar UV activity over a complete solar cycle, beginning in March 1985 and continuing as of this writing. The NOAA-9 solar irradiance data set includes the minimum between Cycles 21-22 and the current minimum at the end of Cycle 22. Although overall solar activity is low during these periods, 27-day rotational modulation is frequently present. The episode of 13-day periodicity observed during September 1994 - March 1995 shows that phenomena previously associated with high levels of solar activity can occur at any point in the solar cycle. The 205 nm irradiance and Mg II index measured by NOAA-9 showed very similar behavior during the Cycle 21-22 minimum in 1985-1986, when 27-day periodicity dominated short-term solar variations, but behaved differently in 1994-1995 during the episode of 13-day periodicity. We plan further investigations into the physical causes of this result, since it affects the extent to which the Mg II index is an accurate proxy for 205 nm irradiance variations during such episodes. The NOAA-9 Mg II data are available.

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

NASA Technical Reports Server (NTRS)

Deland, Matthew T.; Cebula, Richard P.

1994-01-01

Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy over Six-Month Intervals.

PubMed

Woods, Thomas N; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is examining the total energy of the irradiance variation during 6-month periods. This duration is selected because a solar active region typically appears suddenly and then takes 5 to 7 months to decay and disperse back into the quiet-Sun network. The solar outburst energy, which is defined as the irradiance integrated over the 6-month period and thus includes the energy from all phases of active region evolution, could be considered the primary cause for the irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the energy spectral variation may provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (6-month) variations from the Solar Radiation and Climate Experiment (SORCE) instruments can be decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These excess and deficit variations are fit over 6-month intervals every 2 months over the mission, and these fitted variations are then integrated over time for the 6-month energy. The dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1400 - 1600 nm range, with all other wavelengths having in-phase variations.

A Semantically Enabled Metadata Repository for Solar Irradiance Data Products

NASA Astrophysics Data System (ADS)

Wilson, A.; Cox, M.; Lindholm, D. M.; Nadiadi, I.; Traver, T.

2014-12-01

The Laboratory for Atmospheric and Space Physics, LASP, has been conducting research in Atmospheric and Space science for over 60 years, and providing the associated data products to the public. LASP has a long history, in particular, of making space-based measurements of the solar irradiance, which serves as crucial input to several areas of scientific research, including solar-terrestrial interactions, atmospheric, and climate. LISIRD, the LASP Interactive Solar Irradiance Data Center, serves these datasets to the public, including solar spectral irradiance (SSI) and total solar irradiance (TSI) data. The LASP extended metadata repository, LEMR, is a database of information about the datasets served by LASP, such as parameters, uncertainties, temporal and spectral ranges, current version, alerts, etc. It serves as the definitive, single source of truth for that information. The database is populated with information garnered via web forms and automated processes. Dataset owners keep the information current and verified for datasets under their purview. This information can be pulled dynamically for many purposes. Web sites such as LISIRD can include this information in web page content as it is rendered, ensuring users get current, accurate information. It can also be pulled to create metadata records in various metadata formats, such as SPASE (for heliophysics) and ISO 19115. Once these records are be made available to the appropriate registries, our data will be discoverable by users coming in via those organizations. The database is implemented as a RDF triplestore, a collection of instances of subject-object-predicate data entities identifiable with a URI. This capability coupled with SPARQL over HTTP read access enables semantic queries over the repository contents. To create the repository we leveraged VIVO, an open source semantic web application, to manage and create new ontologies and populate repository content. A variety of ontologies were used in

Duties to Extraterrestrial Microscopic Organisms

NASA Astrophysics Data System (ADS)

Cockell, C. S.

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.

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

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

A search strategy for SETI - The search for extraterrestrial intelligence

NASA Technical Reports Server (NTRS)

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

1980-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2006-12-01

The opportunity to insert state-of-the-art solar irradiance measurements and calculations, with subtle perturbations, into a narrow spectral resolution radiative transfer model has recently been facilitated through release of MODTRAN-5 (MOD5). The new solar data are from: (1) SORCE satellite measurements of solar variability over solar rotation cycle, & (2) ultra-narrow calculation of a new solar source irradiance, extending over the full MOD5 spectral range, from 0.2 um to far-IR. MODTRAN-5, MODerate resolution radiance and TRANsmittance code, has been developed collaboratively by Air Force Research Laboratory and Spectral Sciences, Inc., with history dating back to LOWTRAN. It includes approximations for all local thermodynamic equilibrium terms associated with molecular, cloud, aerosol and surface components for emission, scattering, and reflectance, including multiple scattering, refraction and a statistical implementation of Correlated-k averaging. The band model is based on 0.1 cm-1 (also 1.0, 5.0 and 15.0 cm-1 statistical binning for line centers within the interval, captured through an exact formulation of the full Voigt line shape. Spectroscopic parameters are from HITRAN 2004 with user-defined options for additional gases. Recent validation studies show MOD5 replicates line-by-line brightness temperatures to within ~0.02ºK average and <1.0ºK RMS. MOD5 can then serve as a surrogate for a variety of perturbation studies, including the two modes for the solar source function, Io. (1) Data from the Solar Radiation and Climate Experiment (SORCE) satellite mission provide state-of-the-art measurements of UV, visible, near-IR, plus total solar radiation, on near real-time basis. These internally consistent estimates of Sun's output over solar rotation and longer time scales are valuable inputs for studying effects of Sun's radiation on Earth's atmosphere and climate. When solar rotation encounters bright plage and dark sunspots, relative variations are

A Center for Extraterrestrial Engineering and Construction (CETEC)

NASA Technical Reports Server (NTRS)

Leigh, Gerald G.

1992-01-01

A group of knowledgeable scientists and engineers in New Mexico has recognized the need for such a testing capability and has proposed a project to evelop an extraterrestrial surface simulation facility. A group of universities, national laboratories, and private industrial firms is proposing to establish a Center for Extraterrestrial Engineering and Construction (CETEC) and to develop large extraterrestrial surface simulation facilities in which this needed testing can be realistically performed. The CETEC is envisioned to be both a center of knowledge and data regarding engineering, construction, mining, and material process operations on extraterrestrial bodies and a set of extraterrestrial surface simulation facilities. The primary CETEC facility is proposed to be a large domed building made of steel reinforced concrete with more than one acre of test floor area covered with several feet of simulated lunar soil and dust. Various aspects of the project are presented in viewgraph form.

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

The NOM-9 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument is one of a series of instruments providing daily solar spectral irradiance measurements in the middle and near ultraviolet since 1978. The SBUV/2 instruments are primarily designed to measure stratospheric profile and total column ozone, using the directional albedo as the input to the ozone processing algorithm. As a result, the SBUV/2 instrument does not have onboard monitoring of all time-dependent response changes. We have applied internal comparisons and vicarious (external) comparisons to determine the long-term instrument characterization for NOAA-9 SBUV/2 to derive accurate solar spectral irradiances from March 1985 to May 1997 spanning two solar cycle minima with a single instrument. The NOAA-9 data show an amplitude of 9.3(+/- 2.3)% (81-day averaged) at 200-205 nm for solar cycle 22. This is consistent with the result of (Delta)F(sub 200-205) = 8.3(+/- 2.6)% for cycle 21 from Nimbus-7 SBUV and (Delta)F(sub 200-205) = 10(+/- 2)% (daily values) for cycle 23 from UARS SUSIM. NOAA-9 data at 245-250 nm show a solar cycle amplitude of (Delta)F(sub 245-250) = 5.7(+/- 1.8)%. NOAA-9 SBUV/2 data can be combined with other instruments to create a 25-year record of solar UV irradiance.

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

NASA Technical Reports Server (NTRS)

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

1982-01-01

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

Isotopic, Chemical and Mineralogical Investigation's of Extraterrestrial Materials

NASA Technical Reports Server (NTRS)

Lugmair, G. W.

2003-01-01

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

Solar Irradiance from GOES Albedo performance in a Hydrologic Model Simulation of Snowmelt Runoff

NASA Astrophysics Data System (ADS)

Sumargo, E.; Cayan, D. R.; McGurk, B. J.

2015-12-01

In many hydrologic modeling applications, solar radiation has been parameterized using commonly available measures, such as the daily temperature range, due to scarce in situ solar radiation measurement network. However, these parameterized estimates often produce significant biases. Here we test hourly solar irradiance derived from the Geostationary Operational Environmental Satellite (GOES) visible albedo product, using several established algorithms. Focusing on the Sierra Nevada and White Mountain in California, we compared the GOES irradiance and that from a traditional temperature-based algorithm with incoming irradiance from pyranometers at 19 stations. The GOES based estimates yielded 21-27% reduction in root-mean-squared error (average over 19 sites). The derived irradiance is then prescribed as an input to Precipitation-Runoff Modeling System (PRMS). We constrain our experiment to the Tuolumne River watershed and focus our attention on the winter and spring of 1996-2014. A root-mean-squared error reduction of 2-6% in daily inflow to Hetch Hetchy at the lower end of the Tuolumne catchment was achieved by incorporating the insolation estimates at only 8 out of 280 Hydrologic Response Units (HRUs) within the basin. Our ongoing work endeavors to apply satellite-derived irradiance at each individual HRU.

8 years of Solar Spectral Irradiance Observations from the ISS with the SOLAR/SOLSPEC Instrument

NASA Astrophysics Data System (ADS)

Damé, L.; Bolsée, D.; Meftah, M.; Irbah, A.; Hauchecorne, A.; Bekki, S.; Pereira, N.; Cessateur, G.; Marchand, M.; Thiéblemont, R.; Foujols, T.

2016-12-01

Accurate measurements of Solar Spectral Irradiance (SSI) are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). The acquisition of a top of atmosphere reference solar spectrum and of its temporal and spectral variability during the unusual solar cycle 24 is of prime interest for these studies. These measurements are performed since April 2008 with the SOLSPEC spectro-radiometer from the far ultraviolet to the infrared (166 nm to 3088 nm). This instrument, developed under a fruitful LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station (ISS). The SOLAR mission, with its actual 8 years duration, will cover almost the entire solar cycle 24. We present here the in-flight operations and performances of the SOLSPEC instrument, including the engineering corrections, calibrations and improved know-how procedure for aging corrections. Accordingly, a SSI reference spectrum from the UV to the NIR will be presented, together with its UV variability, as measured by SOLAR/SOLSPEC. Uncertainties on these measurements and comparisons with other instruments will be briefly discussed.

A new method for reconstruction of solar irradiance

NASA Astrophysics Data System (ADS)

Privalsky, Victor

2018-07-01

The purpose of this research is to show how time series should be reconstructed using an example with the data on total solar irradiation (TSI) of the Earth and on sunspot numbers (SSN) since 1749. The traditional approach through regression equation(s) is designed for time-invariant vectors of random variables and is not applicable to time series, which present random functions of time. The autoregressive reconstruction (ARR) method suggested here requires fitting a multivariate stochastic difference equation to the target/proxy time series. The reconstruction is done through the scalar equation for the target time series with the white noise term excluded. The time series approach is shown to provide a better reconstruction of TSI than the correlation/regression method. A reconstruction criterion is introduced which allows one to define in advance the achievable level of success in the reconstruction. The conclusion is that time series, including the total solar irradiance, cannot be reconstructed properly if the data are not treated as sample records of random processes and analyzed in both time and frequency domains.

Tilt to horizontal global solar irradiance conversion: application to PV systems data

NASA Astrophysics Data System (ADS)

Housmans, Caroline; Leloux, Jonathan; Bertrand, Cédric

2017-04-01

Many transposition models have been proposed in the literature to convert solar irradiance on the horizontal plane to that on a tilted plane requiring that at least two of the three solar components (i.e. global, direct and diffuse) are known. When only global irradiance measurements are available, the conversion from horizontal to tilted planes is still possible but in this case transposition models have to be coupled with decomposition models (i.e. models that predict the direct and diffuse components from the global one). Here, two different approaches have been considered to solve the reverse process, i.e. the conversion from tilted to horizontal: (i) one-sensor approach and (ii) multi-sensors approach. Because only one tilted plane is involved in the one-sensor approach, a decomposition model need to be coupled with a transposition model to solve the problem. By contrast, at least two tilted planes being considered in the multi-sensors approach, only a transposition model is required to perform the conversion. First, global solar irradiance measurements recorded on the roof of the Royal Meteorological Institute of Belgium's radiation tower in Uccle were used to evaluate the performance of both approaches. Four pyranometers (one mounted in the horizontal plane and three on inclined surfaces with different tilts and orientations) were involved in the validation exercise. Second, the inverse transposition was applied to tilted global solar irradiance values retrieved from the energy production registered at residential PV systems located in the vicinity of Belgian radiometric stations operated by RMI (for validation purposes).

Photometric measurements of solar irradiance variations due to sunspots

NASA Technical Reports Server (NTRS)

Chapman, G. A.; Herzog, A. D.; Laico, D. E.; Lawrence, J. K.; Templer, M. S.

1989-01-01

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.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-10-28

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

Increasing the temporal resolution of direct normal solar irradiance forecasted series

NASA Astrophysics Data System (ADS)

Fernández-Peruchena, Carlos M.; Gastón, Martin; Schroedter-Homscheidt, Marion; Marco, Isabel Martínez; Casado-Rubio, José L.; García-Moya, José Antonio

2017-06-01

A detailed knowledge of the solar resource is a critical point in the design and control of Concentrating Solar Power (CSP) plants. In particular, accurate forecasting of solar irradiance is essential for the efficient operation of solar thermal power plants, the management of energy markets, and the widespread implementation of this technology. Numerical weather prediction (NWP) models are commonly used for solar radiation forecasting. In the ECMWF deterministic forecasting system, all forecast parameters are commercially available worldwide at 3-hourly intervals. Unfortunately, as Direct Normal solar Irradiance (DNI) exhibits a great variability due to the dynamic effects of passing clouds, 3-h time resolution is insufficient for accurate simulations of CSP plants due to their nonlinear response to DNI, governed by various thermal inertias due to their complex response characteristics. DNI series of hourly or sub-hourly frequency resolution are normally used for an accurate modeling and analysis of transient processes in CSP technologies. In this context, the objective of this study is to propose a methodology for generating synthetic DNI time series at 1-h (or higher) temporal resolution from 3-h DNI series. The methodology is based upon patterns as being defined with help of the clear-sky envelope approach together with a forecast of maximum DNI value, and it has been validated with high quality measured DNI data.

The Latest SORCE Solar Spectral Irradiance Data Release: Inter-Comparison and a First Look at TSIS SIM Measurement.

NASA Astrophysics Data System (ADS)

Beland, S.; Sandoval, L.; Vanier, B.; Elliott, J.; Harder, J. W.; Snow, M. A.; Woods, T. N.; Richard, E. C.; Pilewskie, P.

2017-12-01

The Spectral Irradiance Monitor (SIM), the SOLar STellar Irradiance Comparison Experiment (SOLSTICE), and the XUV Photometer System (XPS) instruments on board the Solar Radiation and Climate Experiment (SORCE) mission have been taking daily Solar spectral irradiance (SSI) measurements since April 2003. We present the latest data releases from these instruments, describing the improvements in the new datasets and the trends measured during Solar cycles 23 and 24. An inter-comparison of the SSI over the overlapping wavelengths for SIM and SOLSTICE is presented as well as, if the data is available, a comparison with the first light measurements from TSIS-SIM.

Temperature dependence of damage coefficient in electron irradiated solar cells

NASA Technical Reports Server (NTRS)

Faith, T. J.

1973-01-01

Measurements of light-generated current vs cell temperature on electron-irradiated n/p silicon solar cells show the temperature coefficient of this current to increase with increasing fluence for both 10-ohm and 20-ohm cells. A relationship between minority-carrier diffusion length and light-generated current was derived by combining measurements of these two parameters: vs fluence at room temperature, and vs cell temperature in cells irradiated to a fluence of 1 x 10 to the 15th power e/sq cm. This relationship was used, together with the light-generated current data, to calculate the temperature dependence of the diffusion-length damage coefficient. The results show a strong decrease in the damage coefficient with increasing temperature in the range experienced by solar panels in synchronous earth orbit.

Biological UV dosimeters in simulated space irradiation conditions

NASA Astrophysics Data System (ADS)

Rontó, G.; Bérces, A.; Fekete, A.; Kovács, G.; Lammer, H.

For the measurement of the harmful biological effect of solar UV radiation bacteriophage T7 and polycrystalline uracil dosimeters were used. For terrestrial dosimetric purposes bacteriophage T7 has been applied in solution, while uracil in the form of thin layers. For space irradiation dosimetry the uracil, phage T7-DNA and bacteriophage T7 thin layer samples were prepared in vacuum tightly closed sandwich forms covered either by calciumfluoride or quartz windows. The experimental conditions tested correspond to the conditions planned in the EXPOSE facility: the samples were surrounded by nitrogen atmosphere at various humidities, their vacuum stability was tested in the vacuum chamber of the Institute of Space Research,, Graz. All kinds of the thin film samples have been stored in an atmosphere containing Nitrogen and Hidrogen, in quality control no change in the structure of them has been found. To attenuate the high extraterrestrial irradiance neutral filters of 0.5 and 1.0 optical densities have been tested. Irradiation of the samples has been performed with various UV sources: solar simulator, low pressure Mercury lamp, Deuterium lamp. Dose-effect functions have been determined using for the evaluation spectrophotometry in the characteristic UV range, HPLC of photoproducts, PCR of two different primer sequences of phage T7-DNA. Photoproduct formation kinetics was followed by the saturation level of uracil thin layer. Attenuation ability of the neutral filters was controlled with low pressure Mercury lamp by the exposure necessary for saturation of uracil dosimeters. A three and tenfold increase in the exposure was found respectively, while the influence of spectral composition of the irradiation source was tested using Deuterium lamp supplied with Ca F2 and quartz filters respectively. A doubling of the irradiance was necessary for the saturation of uracil with quartz filter.

Solar Spectral Irradiance Reconstruction over 9 Millennia from a Composite 14C and 10Be Series

NASA Astrophysics Data System (ADS)

Wu, C. J.; Usoskin, I. G.; Krivova, N.; Kovaltsov, G.; Solanki, S. K.

2017-12-01

The Sun is the main external energy source to the Earth and thus the knowledge of solar variability on different time scales is important for understanding the solar influence on the terrestrial atmosphere and climate. The overall energy input and its spectral distribution are described by the total (TSI) and spectral (SSI) solar irradiance, respectively. Direct measurements of the solar irradiance provide information on solar variability on the decadal and shorter time scales, while the sunspot number record covers four centuries. On yet longer time scales only indirect proxies can be used, such as the concentrations of the cosmogenic isotopes 10Be and 14C in terrestrial archives. These isotopes are produced in the terrestrial atmosphere by impinging cosmic rays, whose flux is modulated by solar activity. Therefore the isotope data retrieved from various natural archives around the globe show a very high degree of similarity reflecting changes in the solar activity. Nevertheless, significant short-term deviations can be observed due to the different geochemical production processes and local climatic conditions. We will present the newest TSI/SSI reconstruction over the last 9000 years based on a new consistent composite multi-isotope proxy series. The solar irradiance reconstruction reveals the global and robust pattern of solar variability in the past.

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

NASA Astrophysics Data System (ADS)

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

2011-01-01

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

Engaging space: extraterrestrial architecture and the human psyche

NASA Astrophysics Data System (ADS)

Marie Seguin, Angel

2005-05-01

The human fascination with exploring and inhabiting the space that lies beyond Earth's atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel.

SETI - The search for extraterrestrial intelligence - Plans and rationale

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

Ultraviolet spectral distribution and erythema-weighted irradiance from indoor tanning devices compared with solar radiation exposures.

PubMed

Sola, Yolanda; Baeza, David; Gómez, Miguel; Lorente, Jerónimo

2016-08-01

Concern regarding the impact of indoor tanning devices on human health has led to different regulations and recommendations, which set limits on erythema-weighted irradiance. Here, we analyze spectral emissions from 52 tanning devices in Spanish facilities and compare them with surface solar irradiance for different solar zenith angles. Whereas most of the devices emitted less UV-B radiation than the midday summer sun, the unweighted UV-A irradiance was 2-6 times higher than solar radiation. Moreover, the spectral distributions of indoor devices were completely different from that of solar radiation, differing in one order of magnitude at some UV-A wavelengths, depending on the lamp characteristics. In 21% of the devices tested, the erythema-weighted irradiance exceeded 0.3Wm(-2): the limit fixed by the European standard and the Spanish regulation. Moreover, 29% of the devices fall within the UV type 4 classification, for which medical advice is required. The high variability in erythema-weighted irradiance results in a wide range of exposure times to reach 1 standard erythemal dose (SED: 100Jm(-2)), with 62% of devices requiring exposures of <10min to reach 1 SED. Nevertheless, the unweighted UV-A dose during this time period would be from 1.4 to 10.3 times more than the solar UV-A dose. Copyright © 2016 Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Pap, Judit

1995-01-01

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

Extraterrestrial Communications.

ERIC Educational Resources Information Center

Deardorff, James W.

1987-01-01

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…

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

NASA Astrophysics Data System (ADS)

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

2010-09-01

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.

Chemical studies on the existence of extraterrestrial life.

PubMed

Ponnamperuma, C; Honda, Y; Navarro-González, R

1992-01-01

Although the search for extraterrestrial intelligence has not produced any direct evidence of extraterrestrial life, the emergence of life on Earth, which appears to be controlled by universal laws of physics and chemistry, must have been repeated elsewhere in the universe. The experimental approaches in our laboratory to understand the origin of life on the Earth are summarized in an attempt to obtain a better insight into the chemical basis of extraterrestrial life.

Effects of Solar Irradiance on Ion Fluxes at Mars. MARS EXPRESS and MAVEN Observations

NASA Astrophysics Data System (ADS)

Dubinin, E.; Fraenz, M.; McFadden, J. P.; Eparvier, F. G.; Brain, D. A.; Jakosky, B. M.; Andrews, D. J.; Barbash, S.

2016-12-01

Recent observations by Mars Express and MAVEN spacecraft have shown that the Martian atmosphere/ionosphere is exposed to the impact of solar wind which results in losses of volatiles from Mars. This erosion is an important factor for the evolution of the Martian atmosphere and its water inventory. To estimate the escape forced by the solar wind during the early Solar system conditions we need to know how the ionosphere of Mars and escape fluxes depend on variations in the strength of the external drivers, in particularly, of solar wind and solar EUV flux. We present multi-instrument observations of the influence of the solar irradiance on the Martian ionosphere and escape fluxes. We use data obtained by the ASPERA-3 and MARSIS experiments on Mars Express and by the STATIC instrument and EUV monitor on MAVEN. Observations by Mars Express supplemented by the EUV monitoring at Earth orbit and translated to Mars orbit provide us information about this dependence over more than 10 years whereas the measurements made by MAVEN provide us for the first time the opportunity to study these processes with simultaneous monitoring of the ionospheric variations, planetary ion fluxes and solar irradiance. We can show that fluxes of planetary ions through different escape channels (trans-terminator fluxes, ion plume, plasma sheet) respond differently on the EUV variations. The most significant effect on the ion scavenging with increase of the solar irradiance is observed for low energy ions extracted from the ionosphere while the ion fluxes in the plume are almost insensitive to the EUV variations.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padovan, Andrea; Col, Davide del

2010-12-15

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

Thin-sectioning and microanalysis of individual extraterrestrial particles

NASA Technical Reports Server (NTRS)

Bradley, J. P.

1986-01-01

A long standing constraint on the study of micrometeorites has centered on difficulties in preparing them for analysis. This is due largely to their small dimensions and consequent practical limitations on sample manipulation. Chondritic micrometeorites provide a good example; although much has been learned about their chemistry and mineralogy almost nothing was known about such basic properties as texture and petrographic associations. The only way to assess such properties is to examine microstructure indigenous to the particles. Unfortunately, almost all micrometeorites, out of necessity, have been crushed and dispersed onto appropriate substances prior to analysis, and most information about texture and petrography was lost. Recently, thin-sections of individual extraterrestrial particles have been prepared using an ultramicrotome equipped with a diamond knife. This procedure has been applied to stratospheric micrometeorites and Solar Max impact debris. In both cases the sections have enabled observation of a variety of internal particle features, including textures, porosity, and petrographic associations. The sectioning procedure is described and analysis results for chondritic micrometeoroids and select particles from Solar Max are presented.

Engaging space: extraterrestrial architecture and the human psyche.

PubMed

Sequin, Angel Marie

2005-01-01

The human fascination with exploring and inhabiting the space that lies beyond Earth's atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel. c2005 Elsevier Ltd. All rights reserved.

An Empirical Model of the Variations of the Solar Lyman-Alpha Spectral Irradiance

NASA Astrophysics Data System (ADS)

Kretzschmar, M.; Snow, M. A.; Curdt, W.

2017-12-01

We propose a simple model that computes the spectral profile of the solar irradiance in the Hydrogen Lyman alpha line, H Ly-α (121.567nm), from 1947 to present. Such a model is relevant for the study of many astronomical environments, from planetary atmospheres to interplanetary medium, and can be used to improve the analysis of data from mission like MAVEN or GOES-16. This empirical model is based on the SOHO/SUMER observations of the Ly-α irradiance over solar cycle 23, which we analyze in details, and relies on the Ly-α integrated irradiance composite. The model reproduces the temporal variability of the spectral profile and matches the independent SORCE/SOSLTICE spectral observations from 2003 to 2007 with an accuracy better than 10%.

Radiance And Irradiance Of The Solar HeII 304 Emission Line

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janjai, Serm

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-derivedmore » 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)« less

Organic Dye Degradation Under Solar Irradiation by Hydrothermally Synthesized ZnS Nanospheres

NASA Astrophysics Data System (ADS)

Samanta, Dhrubajyoti; Chanu, T. Inakhunbi; Basnet, Parita; Chatterjee, Somenath

2018-02-01

The green synthesis of ZnS nanospheres using Citrus limetta (sweet lime) juice as a capping agent through a conventional hydrothermal method was studied. The particle size, morphology, chemical composition, band gap, and optical properties of the synthesized ZnS nanospheres were characterized using x-ray diffraction spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet-visible spectroscopy. The photocatalytic activity of the ZnS nanospheres was evaluated by degradation of rhodamine B (RhB) and methyl orange (MO) under solar irradiation. Upon 150 min of solar irradiation, the extent of degradation was 94% and 77% for RhB and MO, respectively.

Comparison of High-Frequency Solar Irradiance: Ground Measured vs. Satellite-Derived

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lave, Matthew; Weekley, Andrew

2016-11-21

High-frequency solar variability is an important to grid integration studies, but ground measurements are scarce. The high resolution irradiance algorithm (HRIA) has the ability to produce 4-sceond resolution global horizontal irradiance (GHI) samples, at locations across North America. However, the HRIA has not been extensively validated. In this work, we evaluate the HRIA against a database of 10 high-frequency ground-based measurements of irradiance. The evaluation focuses on variability-based metrics. This results in a greater understanding of the errors in the HRIA as well as suggestions for improvement to the HRIA.

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

NASA Astrophysics Data System (ADS)

Wang, Hongrui; Fang, Wei; Li, Huiduan

2015-04-01

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

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

PubMed

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

2010-03-01

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

Short-term solar irradiance forecasting via satellite/model coupling

DOE PAGES

Miller, Steven D.; Rogers, Matthew A.; Haynes, John M.; ...

2017-12-01

The short-term (0-3 h) prediction of solar insolation for renewable energy production is a problem well-suited to satellite-based techniques. The spatial, spectral, temporal and radiometric resolution of instrumentation hosted on the geostationary platform allows these satellites to describe the current cloud spatial distribution and optical properties. These properties relate directly to the transient properties of the downwelling solar irradiance at the surface, which come in the form of 'ramps' that pose a central challenge to energy load balancing in a spatially distributed network of solar farms. The short-term evolution of the cloud field may be approximated to first order simplymore » as translational, but care must be taken in how the advection is handled and where the impacts are assigned. In this research, we describe how geostationary satellite observations are used with operational cloud masking and retrieval algorithms, wind field data from Numerical Weather Prediction (NWP), and radiative transfer calculations to produce short-term forecasts of solar insolation for applications in solar power generation. The scheme utilizes retrieved cloud properties to group pixels into contiguous cloud objects whose future positions are predicted using four-dimensional (space + time) model wind fields, selecting steering levels corresponding to the cloud height properties of each cloud group. The shadows associated with these clouds are adjusted for sensor viewing parallax displacement and combined with solar geometry and terrain height to determine the actual location of cloud shadows. For mid/high-level clouds at mid-latitudes and high solar zenith angles, the combined displacements from these geometric considerations are non-negligible. The cloud information is used to initialize a radiative transfer model that computes the direct and diffuse-sky solar insolation at both shadow locations and intervening clear-sky regions. Here, we describe the formulation of

Short-term solar irradiance forecasting via satellite/model coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Steven D.; Rogers, Matthew A.; Haynes, John M.

The short-term (0-3 h) prediction of solar insolation for renewable energy production is a problem well-suited to satellite-based techniques. The spatial, spectral, temporal and radiometric resolution of instrumentation hosted on the geostationary platform allows these satellites to describe the current cloud spatial distribution and optical properties. These properties relate directly to the transient properties of the downwelling solar irradiance at the surface, which come in the form of 'ramps' that pose a central challenge to energy load balancing in a spatially distributed network of solar farms. The short-term evolution of the cloud field may be approximated to first order simplymore » as translational, but care must be taken in how the advection is handled and where the impacts are assigned. In this research, we describe how geostationary satellite observations are used with operational cloud masking and retrieval algorithms, wind field data from Numerical Weather Prediction (NWP), and radiative transfer calculations to produce short-term forecasts of solar insolation for applications in solar power generation. The scheme utilizes retrieved cloud properties to group pixels into contiguous cloud objects whose future positions are predicted using four-dimensional (space + time) model wind fields, selecting steering levels corresponding to the cloud height properties of each cloud group. The shadows associated with these clouds are adjusted for sensor viewing parallax displacement and combined with solar geometry and terrain height to determine the actual location of cloud shadows. For mid/high-level clouds at mid-latitudes and high solar zenith angles, the combined displacements from these geometric considerations are non-negligible. The cloud information is used to initialize a radiative transfer model that computes the direct and diffuse-sky solar insolation at both shadow locations and intervening clear-sky regions. Here, we describe the formulation of

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

NASA Astrophysics Data System (ADS)

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

2011-06-01

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

ACRIM3 and the Total Solar Irradiance database

NASA Astrophysics Data System (ADS)

Willson, Richard C.

2014-08-01

The effects of scattering and diffraction on the observations of the ACRIMSAT/ACRIM3 satellite TSI monitoring mission have been characterized by the preflight calibration approach for satellite total solar irradiance (TSI) sensors implemented at the LASP/TRF (Laboratory for Atmospheric and Space Physics/Total Solar Irradiance Radiometer Facility). The TRF also calibrates the SI (International System of units) traceability to the NIST (National Institute of Standards and Technology) cryo-radiometric scale. ACRIM3's self-calibration agrees with NIST to within the uncertainty of the test procedure (˜500 ppm). A correction of ˜5000 ppm was found for scattering and diffraction that has significantly reduced the scale difference between the results of the ACRIMSAT/ACRIM3 and SORCE/TIM satellite experiments. Algorithm updates reflecting more than 10 years of mission experience have been made that further improve the ACRIM3 results by eliminating some thermally driven signal and increasing the signal to noise ratio. The result of these changes is a more precise and detailed picture of TSI variability. Comparison of the results from the ACRIM3, SORCE/TIM and SOHO/VIRGO satellite experiments demonstrate the near identical detection of TSI variability on all sub-annual temporal and amplitude scales during the TIM mission. The largest occurs at the rotational period of the primary solar activity longitudes. On the decadal timescale, while ACRIM3 and VIRGO results exhibit close agreement throughout, TIM exhibits a consistent 500 ppm upward trend relative to ACRIM3 and VIRGO. A solar magnetic activity area proxy for TSI has been used to demonstrate that the ACRIM TSI composite and its +0.037 %/decade TSI trend during solar cycles 21-23 is the most likely correct representation of the extant satellite TSI database. The occurrence of this trend during the last decades of the 20th century supports a more robust contribution of TSI variation to detected global temperature increase

Solar Spectral Irradiance Changes During Cycle 24

NASA Technical Reports Server (NTRS)

Marchenko, Sergey; Deland, Matthew

2014-01-01

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

Dancing to the MUSSIC: Steps towards creating a Multisatellite Ultraviolet Solar Spectral Irradiance Composite

NASA Astrophysics Data System (ADS)

Snow, M. A.; Machol, J. L.; Richard, E. C.

2016-12-01

Solar spectral irradiance (SSI) has been measured since the beginning of the satellite era in 1978, but the observational record has many gaps in both wavelength and time. We describe our current effort in linking several such datasets ranging from the Extreme Ultraviolet to the Near Ultraviolet (0-400 nm). This wavelength range includes two important solar activity proxies, the Magnesium II core—to-wing ratio and the Lyman alpha irradiance, and special attention will be applied to these two wavelength intervals.

Analytical SuperSTEM for extraterrestrial materials research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, J P; Dai, Z R

2009-09-08

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

AEM of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Mackinnon, I. D. R.

1982-01-01

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

New Solar Irradiance Measurements from the Miniature X-Ray Solar Spectrometer Cubesat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, Thomas N.; Jones, Andrew; Kohnert, Richard

The goal of the Miniature X-ray Solar Spectrometer ( MinXSS ) CubeSat is to explore the energy distribution of soft X-ray (SXR) emissions from the quiescent Sun, active regions, and during solar flares and to model the impact on Earth's ionosphere and thermosphere. The energy emitted in the SXR range (0.1–10 keV) can vary by more than a factor of 100, yet we have limited spectral measurements in the SXRs to accurately quantify the spectral dependence of this variability. The MinXSS primary science instrument is an Amptek, Inc. X123 X-ray spectrometer that has an energy range of 0.5–30 keV withmore » a nominal 0.15 keV energy resolution. Two flight models have been built. The first, MinXSS -1, has been making science observations since 2016 June 9 and has observed numerous flares, including more than 40 C-class and 7 M-class flares. These SXR spectral measurements have advantages over broadband SXR observations, such as providing the capability to derive multiple-temperature components and elemental abundances of coronal plasma, improved irradiance accuracy, and higher resolution spectral irradiance as input to planetary ionosphere simulations. MinXSS spectra obtained during the M5.0 flare on 2016 July 23 highlight these advantages and indicate how the elemental abundance appears to change from primarily coronal to more photospheric during the flare. MinXSS -1 observations are compared to the Geostationary Operational Environmental Satellite ( GOES ) X-ray Sensor (XRS) measurements of SXR irradiance and estimated corona temperature. Additionally, a suggested improvement to the calibration of the GOES XRS data is presented.« less

Design principles and field performance of a solar spectral irradiance meter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatsiankou, V.; Hinzer, K.; Haysom, J.

2016-08-01

A solar spectral irradiance meter (SSIM), designed for measuring the direct normal irradiance (DNI) in six wavelength bands, has been combined with models to determine key atmospheric transmittances and the resulting spectral irradiance distribution of DNI under all sky conditions. The design principles of the SSIM, implementation of a parameterized transmittance model, and field performance comparisons of modeled solar spectra with reference radiometer measurements are presented. Two SSIMs were tested and calibrated at the National Renewable Energy Laboratory (NREL) against four spectroradiometers and an absolute cavity radiometer. The SSIMs' DNI was on average within 1% of the DNI values reportedmore » by one of NREL's primary absolute cavity radiometers. An additional SSIM was installed at the SUNLAB Outdoor Test Facility in September 2014, with ongoing collection of environmental and spectral data. The SSIM's performance in Ottawa was compared against a commercial pyrheliometer and a spectroradiometer over an eight month study. The difference in integrated daily spectral irradiance between the SSIM and the ASD spectroradiometer was found to be less than 1%. The cumulative energy density collected by the SSIM over this duration agreed with that measured by an Eppley model NIP pyrheliometer to within 0.5%. No degradation was observed.« less

Effect of solar irradiation on extracellular enzymes of Aeromonas proteolytica

NASA Technical Reports Server (NTRS)

Foster, B. G.

1973-01-01

The bacterium Aeromonas proteolytica was selected for studying the effects of solar irradiation on extracellular enzymes because it produces an endopeptidase that is capable of degrading proteins and a hemolysin that is active in lysing human erythrocytes. Possible alterations in the rate of enzyme production in response to the test conditions are currently underway and are not available for this preliminary report. Completed viability studies are indicative that little difference exists among the survival curves derived for cells exposed to various components of ultraviolet irradiation in space.

Solar UV irradiation conditions on the surface of Mars.

PubMed

Rontó, Györgyi; Bérces, Attila; Lammer, Helmut; Cockell, Charles S; Molina-Cuberos, Gregorio J; Patel, Manish R; Selsis, Franck

2003-01-01

The UV radiation environment on planetary surfaces and within atmospheres is of importance in a wide range of scientific disciplines. Solar UV radiation is a driving force of chemical and organic evolution and serves also as a constraint in biological evolution. In this work we modeled the transmission of present and early solar UV radiation from 200 to 400 nm through the present-day and early (3.5 Gyr ago) Martian atmosphere for a variety of possible cases, including dust loading, observed and modeled O3 concentrations. The UV stress on microorganisms and/or molecules essential for life was estimated by using DNA damaging effects (specifically bacteriophage T7 killing and uracil dimerization) for various irradiation conditions on the present and ancient Martian surface. Our study suggests that the UV irradiance on the early Martian surface 3.5 Gyr ago may have been comparable with that of present-day Earth, and though the current Martian UV environment is still quite severe from a biological viewpoint, we show that substantial protection can still be afforded under dust and ice.

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

NASA Technical Reports Server (NTRS)

Li, S. S.

1981-01-01

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

Solar Irradiance from 165 to 400 nm in 2008 and UV Variations in Three Spectral Bands During Solar Cycle 24

NASA Astrophysics Data System (ADS)

Meftah, M.; Bolsée, D.; Damé, L.; Hauchecorne, A.; Pereira, N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thiéblemont, R.

2016-12-01

Accurate measurements of the solar spectral irradiance (SSI) and its temporal variations are of primary interest to better understand solar mechanisms, and the links between solar variability and Earth's atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to carry out SSI measurements from 165 to 3088 nm. We focus here on the ultraviolet (UV) part of the measured solar spectrum (wavelengths less than 400 nm) because the UV part is potentially important for understanding the solar forcing of Earth's atmosphere and climate. We present here SOLAR/SOLSPEC UV data obtained since 2008, and their variations in three spectral bands during Solar Cycle 24. They are compared with previously reported UV measurements and model reconstructions, and differences are discussed.

FIVE YEARS OF SYNTHESIS OF SOLAR SPECTRAL IRRADIANCE FROM SDID/SISA AND SDO /AIA IMAGES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontenla, J. M.; Codrescu, M.; Fedrizzi, M.

In this paper we describe the synthetic solar spectral irradiance (SSI) calculated from 2010 to 2015 using data from the Atmospheric Imaging Assembly (AIA) instrument, on board the Solar Dynamics Observatory spacecraft. We used the algorithms for solar disk image decomposition (SDID) and the spectral irradiance synthesis algorithm (SISA) that we had developed over several years. The SDID algorithm decomposes the images of the solar disk into areas occupied by nine types of chromospheric and 5 types of coronal physical structures. With this decomposition and a set of pre-computed angle-dependent spectra for each of the features, the SISA algorithm ismore » used to calculate the SSI. We discuss the application of the basic SDID/SISA algorithm to a subset of the AIA images and the observed variation occurring in the 2010–2015 period of the relative areas of the solar disk covered by the various solar surface features. Our results consist of the SSI and total solar irradiance variations over the 2010–2015 period. The SSI results include soft X-ray, ultraviolet, visible, infrared, and far-infrared observations and can be used for studies of the solar radiative forcing of the Earth’s atmosphere. These SSI estimates were used to drive a thermosphere–ionosphere physical simulation model. Predictions of neutral mass density at low Earth orbit altitudes in the thermosphere and peak plasma densities at mid-latitudes are in reasonable agreement with the observations. The correlation between the simulation results and the observations was consistently better when fluxes computed by SDID/SISA procedures were used.« less

Simulation of temperature effect on microalgae culture in a tubular photo bioreactor for local solar irradiance

NASA Astrophysics Data System (ADS)

Shahriar, M.; Deb, Ujjwal Kumar; Rahman, Kazi Afzalur

2017-06-01

Microalgae based biofuel is now an emerging source of renewable energy alternative to the fossil fuel. This paper aims to present computational model of microalgae culture taking effect of solar irradiance and corresponding temperature in a photo bioreactor (PBR). As microalgae is a photosynthetic microorganism, so irradiance of sunlight is one of the important limiting factors for the proper growth of microalgae cells as temperature is associated with it. We consider the transient behaviour of temperature inside the photo bioreactor for a microalgae culture. The optimum range of temperature for outdoor cultivation of microalgae is about 16-35°c and out of this range the cell growth inhibits. Many correlations have already been established to investigate the heat transfer phenomena inside a tubular PBR. However, none of them are validated yet numerically by using a user defined function in a simulated model. A horizontal tubular PBR length 20.5m with radius 0.05m has taken account to investigate the temperature effect for the growth of microalgae cell. As the solar irradiance varies at any geographic latitude for a year so an empirical relation is established between local solar irradiance and temperature to simulate the effect. From our simulation, we observed that the growth of microalgae has a significant effect of temperature and the solar irradiance of our locality is suitable for the culture of microalgae.

FINDING EXTRATERRESTRIAL LIFE USING GROUND-BASED HIGH-DISPERSION SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snellen, I. A. G.; Le Poole, R.; Brogi, M.

2013-02-20

Exoplanet observations promise one day to unveil the presence of extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium would point to large-scale biological activity just as oxygen and methane do in the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a dedicated space telescope to search for biomarker gases in exoplanet atmospheres will be launched within the next 25 years. Here we show that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through transit observations. Recent results on hot Jupiters show the enormous potential ofmore » high-dispersion spectroscopy to separate the extraterrestrial and telluric signals, making use of the Doppler shift of the planet. The transmission signal of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor of three smaller than that of carbon monoxide recently detected in the hot Jupiter {tau} Booetis b, albeit such a star will be orders of magnitude fainter. We show that if Earth-like planets are common, the planned extremely large telescopes can detect oxygen within a few dozen transits. Ultimately, large arrays of dedicated flux-collector telescopes equipped with high-dispersion spectrographs can provide the large collecting area needed to perform a statistical study of life-bearing planets in the solar neighborhood.« less

8 years of Solar Spectral Irradiance Variability Observed from the ISS with the SOLAR/SOLSPEC Instrument

NASA Astrophysics Data System (ADS)

Damé, Luc; Bolsée, David; Meftah, Mustapha; Irbah, Abdenour; Hauchecorne, Alain; Bekki, Slimane; Pereira, Nuno; Cessateur, Marchand; Gäel; , Marion; et al.

2016-10-01

Accurate measurements of Solar Spectral Irradiance (SSI) are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). The acquisition of a top of atmosphere reference solar spectrum and of its temporal and spectral variability during the unusual solar cycle 24 is of prime interest for these studies. These measurements are performed since April 2008 with the SOLSPEC spectro-radiometer from the far ultraviolet to the infrared (166 nm to 3088 nm). This instrument, developed under a fruitful LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station (ISS). The SOLAR mission, with its actual 8 years duration, will cover almost the entire solar cycle 24. We present here the in-flight operations and performances of the SOLSPEC instrument, including the engineering corrections, calibrations and improved know-how procedure for aging corrections. Accordingly, a SSI reference spectrum from the UV to the NIR will be presented, together with its variability in the UV, as measured by SOLAR/SOLSPEC for 8 years. Uncertainties on these measurements and comparisons with other instruments will be briefly discussed.

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Evaluation of the Delta-T SPN1 radiometer for the measurement of solar irradiance components

NASA Astrophysics Data System (ADS)

Estelles, Victor; Serrano, David; Segura, Sara; Wood, John; Webb, Nick; Utrillas, Maria Pilar

2016-04-01

In this study we analyse the performance of an SPN1 radiometer built by Delta-T Devices Ltd. to retrieve global solar irradiance at ground and its components (diffuse, direct) in comparison with measurements from two Kipp&Zonen CMP21 radiometers and a Kipp&Zonen CHP1 pirheliometer, mounted on an active Solys-2 suntracker at the Burjassot site (Valencia, Spain) using data acquired every minute during years 2013 - 2015. The measurement site is close to sea level (60 m a.s.l.), near the Mediterranean coast (10 km) and within the metropolitan area of Valencia City (over 1.500.000 inhabitants). The SPN1 is an inexpensive and versatile instrument for the measurement of the three components of the solar radiation without any mobile part and without any need to azimuthally align the instrument to track the sun (http://www.delta-t.co.uk). The three components of the solar radiation are estimated from a combination of measurements performed by 7 different miniature thermopiles. The SPN1 pyranometer measures the irradiance between 400 and 2700 nm, and the nominal uncertainty for the individual readings is about 8% ± 10 W/m2 (5% for the daily averages). The pyranometer Kipp&Zonen CMP21 model is a secondary standard for the measurement of broadband solar global irradiance in horizontal planes. Two ventilated CMP21 are used for the measurement of the global and diffuse irradiances. The expected total daily uncertainty of the radiometer is estimated to be 2%. The pirheliometer Kipp&Zonen CHP1 is designed for the measurement of the direct irradiance. The principles are similar to the CMP21 pyranometer. The results of the comparison show that the global irradiance from the SPN1 compares very well with the CMP21, with absolute RMSD and MBD differences below the combined uncertainties (15 W/m2 and -5.4 W/m2, respectively; relative RMSD of 3.1%). Both datasets are very well correlated, with a correlation coefficient higher than 0.997 and a slope and intercept very close to 1 and 0

A New Revision of the Solar Irradiance Climate Data Record Incorporates Recent Research into Proxies of Sunspot Darkening and the Sunspot Number Record

NASA Astrophysics Data System (ADS)

Coddington, O.; Lean, J.; Pilewskie, P.; Baranyi, T.; Snow, M. A.; Kopp, G.; Richard, E. C.; Lindholm, C.

2017-12-01

An operational climate data record (CDR) of total and spectral solar irradiance became available in November 2015 as part of the National Oceanographic and Atmospheric Administration's National Centers for Environmental Information Climate Data Record Program. The data record, which is updated quarterly, is available from 1610 to the present as yearly-average values and from 1882 to the present as monthly- and daily-averages, with associated time and wavelength-dependent uncertainties. It was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics and the Naval Research Laboratory, and, together with the source code and supporting documentation, is available at https://www.ncdc.noaa.gov/cdr/. In the Solar Irradiance CDR, total solar irradiance (TSI) and solar spectral irradiance (SSI) are estimated from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk. The models are constructed using linear regression of proxies of solar sunspot and facular features with the approximately decade-long irradiance observations from the SOlar Radiation and Climate Experiment. A new revision of this data record was recently released in an ongoing effort to reduce solar irradiance uncertainties in two ways. First, the sunspot darkening proxy was revised using a new cross calibration of the current sunspot region observations made by the Solar Observing Optical Network with the historical records of the Royal Greenwich Observatory. This implementation affects modeled irradiances from 1882 - 1978. Second, the impact of a revised record of sunspot number by the Sunspot Index and Long-term Solar Observations center on modeled irradiances was assessed. This implementation provides two different reconstructions of historical, yearly-averaged irradiances from 1610-1881. Additionally, we show new, preliminary results that demonstrate improvements in modeled TSI by using

A technique for global monitoring of net solar irradiance at the ocean surface. II - Validation

NASA Technical Reports Server (NTRS)

Chertock, Beth; Frouin, Robert; Gautier, Catherine

1992-01-01

The generation and validation of the first satellite-based long-term record of surface solar irradiance over the global oceans are addressed. The record is generated using Nimbus-7 earth radiation budget (ERB) wide-field-of-view plentary-albedo data as input to a numerical algorithm designed and implemented based on radiative transfer theory. The mean monthly values of net surface solar irradiance are computed on a 9-deg latitude-longitude spatial grid for November 1978-October 1985. The new data set is validated in comparisons with short-term, regional, high-resolution, satellite-based records. The ERB-based values of net surface solar irradiance are compared with corresponding values based on radiance measurements taken by the Visible-Infrared Spin Scan Radiometer aboard GOES series satellites. Errors in the new data set are estimated to lie between 10 and 20 W/sq m on monthly time scales.

Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms

NASA Astrophysics Data System (ADS)

Dasi-Espuig, M.; Jiang, J.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Yeo, K. L.

2016-05-01

Aims: We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a surface flux transport model fed with semi-synthetic records of emerging sunspot groups. Methods: The record of sunspot group areas and positions from the Royal Greenwich Observatory (RGO) is only available since 1874. We used statistical relationships between the properties of sunspot group emergence, such as the latitude, area, and tilt angle, and the sunspot cycle strength and phase to produce semi-synthetic sunspot group records starting in the year 1700. The semi-synthetic records are fed into a surface flux transport model to obtain daily simulated magnetograms that map the distribution of the magnetic flux in active regions (sunspots and faculae) and their decay products on the solar surface. The magnetic flux emerging in ephemeral regions is accounted for separately based on the concept of extended cycles whose length and amplitude are linked to those of the sunspot cycles through the sunspot number. The magnetic flux in each surface component (sunspots, faculae and network, and ephemeral regions) was used to compute the spectral and total solar irradiance (TSI) between the years 1700 and 2009. This reconstruction is aimed at timescales of months or longer although the model returns daily values. Results: We found that SATIRE-T2, besides reproducing other relevant observations such as the total magnetic flux, reconstructs the TSI on timescales of months or longer in good agreement with the PMOD composite of observations, as well as with the reconstruction starting in 1878 based on the RGO-SOON data. The model predicts an increase in the TSI of 1.2+0.2-0.3 Wm-2 between 1700 and the present. The spectral irradiance reconstruction is in good agreement with the UARS/SUSIM measurements as well as the Lyman-α composite. The

Spectral Monte Carlo simulation of collimated solar irradiation transfer in a water-filled prismatic louver.

PubMed

Cai, Yaomin; Guo, Zhixiong

2018-04-20

The Monte Carlo model was developed to simulate the collimated solar irradiation transfer and energy harvest in a hollow louver made of silica glass and filled with water. The full solar spectrum from the air mass 1.5 database was adopted and divided into various discrete bands for spectral calculations. The band-averaged spectral properties for the silica glass and water were obtained. Ray tracing was employed to find the solar energy harvested by the louver. Computational efficiency and accuracy were examined through intensive comparisons of different band partition approaches, various photon numbers, and element divisions. The influence of irradiation direction on the solar energy harvest efficiency was scrutinized. It was found that within a 15° polar angle of incidence, the harvested solar energy in the louver was high, and the total absorption efficiency reached 61.2% under normal incidence for the current louver geometry.

Models of Solar Irradiance Variability and the Instrumental Temperature Record

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

The Scientific Search for Extraterrestrial Intelligence: a Sociological Analysis.

NASA Astrophysics Data System (ADS)

Romesberg, Daniel Ray

1992-01-01

This study examines the search for extraterrestrial intelligence, as it has been conducted by scientists over the past century. The following questions are explored: (1) What are the historical patterns of American scientific interest in extraterrestrial intelligence? From a sociology of science perspective, how can these patterns of interest be explained? (2) Who are the most prominent scientists involved in SETI? What are their academic backgrounds? (3) How has the rather exotic idea of extraterrestrial intelligence managed to penetrate the realm of respectable science?. In order to measure the historical fluctuations of scientific interest in extraterrestrial intelligence, a frequency distribution of relevant articles published in American scientific journals over the past century has been constructed. The core scholars of the "extraterrestrial" field have been determined via citation analysis, in a selected portion of the scientific literature. An analysis of recent scientific literature on the Search for Extraterrestrial Intelligence (SETI) has revealed a number of tactics of legitimation and de-legitimation used by SETI proponents, as well as opponents. This study has generated the following findings: (1) Historically, there are three factors which tend to stimulate general scientific interest in extraterrestrial intelligence: First, the strong demonstration of the plausibility of extraterrestrial intelligence, or life, especially in a tangible, and therefore studiable location. Scientific laboratories are primary agents of plausibility here. Second, the organized political activity of SETI scientists. Third, the availability of government funding for searches for extraterrestrial intelligence, or life. (2) Statistically, the leading scholars of modern SETI are Sagan, Drake and Morrison. The field itself tends to be dominated by astronomers and physicists. (3) Because SETI has no concrete data, and is easily stigmatized as an illegitimate scientific activity

Crystallographic Characterization of Extraterrestrial Materials by Energy-Scanning X-ray Diffraction

NASA Technical Reports Server (NTRS)

Hagiya, Kenji; Mikouchi, Takashi; Ohsumi, Kazumasa; Terada, Yasuko; Yagi, Naoto; Komatsu, Mutsumi; Yamaguchi, Shoki; Hirata, Arashi; Kurokawa, Ayaka; Zolensky, Michael E. (Principal Investigator)

2016-01-01

We have continued our long-term project using X-ray diffraction to characterize a wide range of extraterrestrial samples. The stationary sample method with polychromatic X-rays is advantageous because the irradiated area of the sample is always same and fixed, meaning that all diffraction spots occur from the same area of the sample, however, unit cell parameters cannot be directly obtained by this method though they are very important for identification of mineral and for determination of crystal structures. In order to obtain the cell parameters even in the case of the sample stationary method, we apply energy scanning of a micro-beam of monochromatic SR at SPring-8.

The Miocene Extraterrestrial Dust Deposition Event Tracked by Helium, Neon, Chromium and Extraterrestrial Insoluble Organic Matter at the Monte Dei Corvi Beach Section

NASA Astrophysics Data System (ADS)

Meier, M. M. M.; Steele, R. C. J.; Schmitz, B.; Piani, L.; Maden, C.; Plant, A. A.; Schönbächler, M.; Busemann, H.

2017-12-01

A temporarily increased flux of extraterrestrial dust to Earth can lead to tell-tale clues in sediments of the same age. A common example is peaks of 3He in sediments, which occur because extraterrestrial material is rich in implanted solar wind that has a high 3He/4He ratio compared to the atmosphere. One of two known 3He-peaks in Cenozoic sediments is found within the Miocene, at an age of about 8 Ma (Tortonian stage). This peak has been tied to the asteroid break-up event which formed the Veritas family (Farley et al., Nature, 2006). The Global Boundary Stratotype Section and Point for the Tortonian is located near Monte Dei Corvi, in Ancona, Italy. It has previously been well characterized using both magneto- and cyclostratigraphy (Hüsing et al., EPSL, 2009), and can thus provide excellent time-constraints on the age of the event, now dated to have started at 8.47±0.05 Ma (Montanari et al., GSA Bulletin, 2017). In this project, we study these sediments with the primary goal of determining the meteoritic type of the extraterrestrial dust. We have been following three different avenues towards that goal: (1) light noble gas (He, Ne) analyses of bulk sediments (Meier et al., Annual Meeting of the Meteoritical Society, 2016), which are used as tracers of dust flux. The measured He vs. Ne allows us to characterize the preservation state of the extraterrestrial noble gases in the sediments (see Chavrit et al., EPSL, 2016); (2) Cr abundance and isotope analysis of bulk sediments and residues, which should allow us to determine the meteoritic type of the deposited dust (e.g., Rotaru et al., Nature, 1992); (3) an attempt to isolate and characterize potentially surviving meteoritic organic matter in the bulk sediments from Monte Dei Corvi. Insoluble organic matter, which contributes 1-2% of the mass in some carbonaceous chondrites (tied to C- and D-type asteroids, like the ones found abundantly in the Veritas family; Ziffer et al., Icarus, 2011) is strongly acid- and

[Current considerations around the search for extraterrestrial life].

PubMed

González de Posada, F

2000-01-01

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.

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

NASA Technical Reports Server (NTRS)

Platnick, Steven; Fontenla, Juan M.

2006-01-01

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

Decoupling Solar Variability and Instrument Trends Using the Multiple Same-Irradiance-Level (MuSIL) Analysis Technique

NASA Astrophysics Data System (ADS)

Woods, Thomas N.; Eparvier, Francis G.; Harder, Jerald; Snow, Martin

2018-05-01

The solar spectral irradiance (SSI) dataset is a key record for studying and understanding the energetics and radiation balance in Earth's environment. Understanding the long-term variations of the SSI over timescales of the 11-year solar activity cycle and longer is critical for many Sun-Earth research topics. Satellite measurements of the SSI have been made since the 1970s, most of them in the ultraviolet, but recently also in the visible and near-infrared. A limiting factor for the accuracy of previous solar variability results is the uncertainties for the instrument degradation corrections, which need fairly large corrections relative to the amount of solar cycle variability at some wavelengths. The primary objective of this investigation has been to separate out solar cycle variability and any residual uncorrected instrumental trends in the SSI measurements from the Solar Radiation and Climate Experiment (SORCE) mission and the Thermosphere, Mesosphere, Ionosphere, Energetic, and Dynamics (TIMED) mission. A new technique called the Multiple Same-Irradiance-Level (MuSIL) analysis has been developed, which examines an SSI time series at different levels of solar activity to provide long-term trends in an SSI record, and the most common result is a downward trend that most likely stems from uncorrected instrument degradation. This technique has been applied to each wavelength in the SSI records from SORCE (2003 - present) and TIMED (2002 - present) to provide new solar cycle variability results between 27 nm and 1600 nm with a resolution of about 1 nm at most wavelengths. This technique, which was validated with the highly accurate total solar irradiance (TSI) record, has an estimated relative uncertainty of about 5% of the measured solar cycle variability. The MuSIL results are further validated with the comparison of the new solar cycle variability results from different solar cycles.

Higher Efficiency for Quasi-Solid State Dye Sensitized Solar Cells Under Low Light Irradiance

NASA Astrophysics Data System (ADS)

Desilva, Ajith; Bandara, T. M. W. J.; Fernado, H. D. N. S.; Fernando, P. S. L.; Dissanayake, M. A. K. L.; Jayasundara, W. J. M. J. S. R.; Furlani, M.; Mellander, B.-E.

2014-03-01

Dye-sensitized solar cells (DSSCs), lower cost solar energy conversion devices are alternative green energy source. The liquid based electrolyte DSSCs have higher efficiencies with many practical issues while the quasi-solid-state DSSCs resolve the key problems but efficiencies are relatively low. Polyacrylonitrile (PAN) based gel polymer electrolytes were fabricated as DSSCs by incorporating ethylene carbonate and propylene carbonate plasticizers and tetrapropylammonium iodide salt. A thin layer of electrolyte was sandwiched between the TiO2 anode (sensitized with N719 dye) and the Pt counter electrode. The electrolyte had an ionic conductivity of 2.6 mS/cm at 25 degrees of Celsius. DSSCs incorporating this gel electrolyte revealed Vsc circuit, Jsc, fill factor (FF) and efficiency values of 0.71 V, 11.8 mA, 51 percent and 4.2 percent respectively under 1 sun irradiation. The efficiency of the cell increased with decreasing solar irradiance achieving up to 10 percent efficiency and 80 percent FF at low irradiance values. This work uncovers that quasi-solid state DSSCs can reach efficiencies close to that of liquid electrolytes based cells.

Recovery of shallow junction GaAs solar cells damaged by electron irradiation

NASA Technical Reports Server (NTRS)

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

1978-01-01

Solar cells operated in space are subject to degradation from electron and proton radiation damage. It has been found that for deep junction p-GaAlAs/p-GaAs solar cells some of the electron radiation damage is removed by annealing the cells at 200 C. The reported investigation shows that shallow junction p-GaAlAs/p-GaAs/n-GaAs heteroface solar cells irradiated with 1 MeV electrons show a more complete recovery of short-circuit current than do the deep junction cells. The heteroface p-GaAlAs/p-GaAs/n-GaAs solar cells studied were fabricated using the etch-back epitaxy process.

Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

NASA Technical Reports Server (NTRS)

Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

1981-01-01

The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

Liberty and the Limits to the Extraterrestrial State

NASA Astrophysics Data System (ADS)

Cockell, C. S.

The physical conditions that inhere in extraterrestrial environments have a tendency to drive society toward collectivist mechanisms of political and economic order to successfully cope with, and prevent possible disaster caused by, the lethal external conditions. Liberty will therefore be eroded by deliberate human action, through extraterrestrial authorities, and through a natural restriction in concepts of liberty that will attend the development and behaviour of people in confined environments. The emergence of extraterrestrial governance that nurtures liberty in outer space will require the formation of many institutions that encourage competition and reduce political and economic monopolies - with the legal system to sustain them. This problem is most clearly manifest in oxygen production. These considerations allow the purpose and limits of the extraterrestrial state and precursor forms of governance to be circumscribed. Far from being a purely speculative enquiry, this discussion allows requirements in physical architecture and social organisation to be identified that can be considered from the earliest stages of space exploration and settlement.

Instrument Description: The Total Solar Irradiance Monitor on the FY-3C Satellite, an Instrument with a Pointing System

NASA Astrophysics Data System (ADS)

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

2017-01-01

The Total Solar Irradiance Monitor (TSIM) onboard the nadir Feng Yun-3C (FY-3C) satellite provides measurements of the total solar irradiance with accurate solar tracking and sound thermal stability of its heat sink. TSIM/FY-3C mainly consists of the pointing system, the radiometer package, the thermal control system, and the electronics. Accurate solar tracking is achieved by the pointing system, which greatly improves the science data quality when compared with the previous TSIM/FY-3A and TSIM/FY-3B. The total solar irradiance (TSI) is recorded by TSIM/FY-3C about 26 times each day, using a two-channel radiometer package. One channel is used to perform routine observation, and the other channel is used to monitor the degradation of the cavity detector in the routine channel. From the results of the ground test, the incoming irradiance is measured by the routine channel (AR1) with a relative uncertainty of 592 ppm. A general description of the TSIM, including the instrument modules, uncertainty evaluation, and its operation, is given in this article.

Calculating Solar Ultraviolet Irradiation Of The Human Cornea And Corresponding Required Sunglass Lens Transmittances

NASA Astrophysics Data System (ADS)

Hoover, Herbert L.; Marsaud, Serge G.

1986-05-01

Tinted ophthalmic lenses are used primarily for eye comfort in a brightly lit environment. An ancillary benefit is the attenuation of ultraviolet radiation. Some national product standards specify quantitative limits for ultraviolet transmittances. Such limits ought to be founded on quantitative estimates of solar irradiances of ocular tissues, with actinic effectiveness taken into account. We use the equations of Green and coworkers for direct and diffuse solar irradiance at the earth's surface to calculate average sky and ground spectral radiances. We use the geometric factors derived by us for the coupling of radiation from these sources to the human cornea. Actinically weighted corneal spectral irradiances integrated over wavelength and time yield peak irradiances and accumulated exposure doses that are compared with recommended exposure limits. This provides the maximal effective ultraviolet transmittances of tinted ophthalmic lenses such that these exposure limits will not be exceeded in the selected exposure environment. The influences on corneal irradiation of such exposure parameters as solar zenith angle, altitude of the exposure site, characteristics of atmospheric aerosols, and ground reflectances are illustrated. The relationships between the effective transmittance (which is a function of the environmental radiation and any actinicweighting function) and readily determined characteristics of the lens itself, viz., its mean transmittance, and a selected spectral transmittance, are derived for three lens transmittance curves. Limits of lens transmittance for the UV-B and UV-A wavelength regions are presented for several representative exposure sites in Europe and the U.S.A.

Irradiation of nitrogen-rich ices by swift heavy ions. Clues for the formation of ultracarbonaceous micrometeorites

NASA Astrophysics Data System (ADS)

Augé, B.; Dartois, E.; Engrand, C.; Duprat, J.; Godard, M.; Delauche, L.; Bardin, N.; Mejía, C.; Martinez, R.; Muniz, G.; Domaracka, A.; Boduch, P.; Rothard, H.

2016-08-01

Context. Extraterrestrial materials, such as meteorites and interplanetary dust particles, provide constraints on the formation and evolution of organic matter in the young solar system. Micrometeorites represent the dominant source of extraterrestrial matter at the Earth's surface, some of them originating from large heliocentric distances. Recent analyses of ultracarbonaceous micrometeorites recovered from Antarctica (UCAMMs) reveal an unusually nitrogen-rich organic matter. Such nitrogen-rich carbonaceous material could be formed in a N2-rich environment, at very low temperature, triggered by energetic processes. Aims: Several formation scenarios have been proposed for the formation of the N-rich organic matter observed in UCAMMs. We experimentally evaluate the scenario involving high energy irradiation of icy bodies subsurface orbiting at large heliocentric distances. Methods: The effect of Galactic cosmic ray (GCR) irradiation of ices containing N2 and CH4 was studied in the laboratory. The N2-CH4 (90:10 and 98:2) ice mixtures were irradiated at 14 K by 44 MeV Ni11+ and 160 MeV Ar15+ swift heavy ion beams. The evolution of the samples was monitored using in-situ Fourier transform infrared spectroscopy. The evolution of the initial ice molecules and new species formed were followed as a function of projectile fluence. After irradiation, the target was annealed to room temperature. The solid residue of the whole process left after ice sublimation was characterized in-situ by infrared spectroscopy, and the elemental composition was measured ex-situ. Results: The infrared bands that appear during irradiation allow us to identify molecules and radicals (HCN, CN-, NH3, ...). The infrared spectra of the solid residues measured at room temperature show similarities with that of UCAMMs. The results point towards the efficient production of a poly-HCN-like residue from the irradiation of N2-CH4 rich surfaces of icy bodies. The room temperature residue provides a viable

Analysis of spatial patterns underlying the linkage between solar irradiance and near-surface air temperatures

NASA Astrophysics Data System (ADS)

Balling, Robert C.; Roy, Shouraseni Sen

2005-06-01

Many scientists have noted that global temperature anomalies were highly correlated with solar irradiance values until sometime in the 1970s, but since that time, the pronounced warming in the near-surface temperature record is not explained by variations or trends in solar receipt. In this investigation, spatial dimensions are explored in the relationship between irradiance and near-surface air temperatures. At the scale of individual 5° by 5° grid cells, the solar control on annual temperature variations is not statistically significant. When the temperature data are aggregated by 5° latitudinal bands, the solar - temperature connect is generally significant, and in every band, there is substantial evidence that a non-solar control has become dominant in recent decades. The buildup of greenhouse gases and/or some other global-scale feedback, such as widespread changes in atmospheric water vapor, emerge as potential explanations for the recent residual warming found in all latitudinal bands.

New Solar Irradiance Measurements from the Miniature X-Ray Solar Spectrometer CubeSat

NASA Astrophysics Data System (ADS)

Woods, Thomas N.; Caspi, Amir; Chamberlin, Phillip C.; Jones, Andrew; Kohnert, Richard; Mason, James Paul; Moore, Christopher S.; Palo, Scott; Rouleau, Colden; Solomon, Stanley C.; Machol, Janet; Viereck, Rodney

2017-02-01

The goal of the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat is to explore the energy distribution of soft X-ray (SXR) emissions from the quiescent Sun, active regions, and during solar flares and to model the impact on Earth's ionosphere and thermosphere. The energy emitted in the SXR range (0.1-10 keV) can vary by more than a factor of 100, yet we have limited spectral measurements in the SXRs to accurately quantify the spectral dependence of this variability. The MinXSS primary science instrument is an Amptek, Inc. X123 X-ray spectrometer that has an energy range of 0.5-30 keV with a nominal 0.15 keV energy resolution. Two flight models have been built. The first, MinXSS-1, has been making science observations since 2016 June 9 and has observed numerous flares, including more than 40 C-class and 7 M-class flares. These SXR spectral measurements have advantages over broadband SXR observations, such as providing the capability to derive multiple-temperature components and elemental abundances of coronal plasma, improved irradiance accuracy, and higher resolution spectral irradiance as input to planetary ionosphere simulations. MinXSS spectra obtained during the M5.0 flare on 2016 July 23 highlight these advantages and indicate how the elemental abundance appears to change from primarily coronal to more photospheric during the flare. MinXSS-1 observations are compared to the Geostationary Operational Environmental Satellite (GOES) X-ray Sensor (XRS) measurements of SXR irradiance and estimated corona temperature. Additionally, a suggested improvement to the calibration of the GOES XRS data is presented.

Evaluation of scenario-specific modeling approaches to predict plane of array solar irradiation

DOE PAGES

Moslehi, Salim; Reddy, T. Agami; Katipamula, Srinivas

2017-12-20

Predicting thermal or electric power output from solar collectors requires knowledge of solar irradiance incident on the collector, known as plane of array irradiance. In the absence of such a measurement, plane of array irradiation can be predicted using relevant transposition models which essentially requires diffuse (or beam) radiation to be to be known along with total horizontal irradiation. The two main objectives of the current study are (1) to evaluate the extent to which the prediction of plane of array irradiance is improved when diffuse radiation is predicted using location-specific regression models developed from on-site measured data as againstmore » using generalized models; and (2) to estimate the expected uncertainties associated with plane of array irradiance predictions under different data collection scenarios likely to be encountered in practical situations. These issues have been investigated using monitored data for several U.S. locations in conjunction with the Typical Meteorological Year, version 3 database. An interesting behavior in the Typical Meteorological Year, version 3 data was also observed in correlation patterns between diffuse and total radiation taken from different years which seems to attest to a measurement problem. Furthermore, the current study was accomplished under a broader research agenda aimed at providing energy managers the necessary tools for predicting, scheduling, and controlling various sub-systems of an integrated energy system.« less

Evaluation of scenario-specific modeling approaches to predict plane of array solar irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moslehi, Salim; Reddy, T. Agami; Katipamula, Srinivas

Predicting thermal or electric power output from solar collectors requires knowledge of solar irradiance incident on the collector, known as plane of array irradiance. In the absence of such a measurement, plane of array irradiation can be predicted using relevant transposition models which essentially requires diffuse (or beam) radiation to be to be known along with total horizontal irradiation. The two main objectives of the current study are (1) to evaluate the extent to which the prediction of plane of array irradiance is improved when diffuse radiation is predicted using location-specific regression models developed from on-site measured data as againstmore » using generalized models; and (2) to estimate the expected uncertainties associated with plane of array irradiance predictions under different data collection scenarios likely to be encountered in practical situations. These issues have been investigated using monitored data for several U.S. locations in conjunction with the Typical Meteorological Year, version 3 database. An interesting behavior in the Typical Meteorological Year, version 3 data was also observed in correlation patterns between diffuse and total radiation taken from different years which seems to attest to a measurement problem. Furthermore, the current study was accomplished under a broader research agenda aimed at providing energy managers the necessary tools for predicting, scheduling, and controlling various sub-systems of an integrated energy system.« less

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

NASA Astrophysics Data System (ADS)

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

2014-10-01

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

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

PubMed Central

Zurbenko, Igor

2014-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1989-01-01

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.

Improving Soft X-Ray Spectral Irradiance Models for Use Throughout the Solar System

NASA Astrophysics Data System (ADS)

Eparvier, F. G.; Thiemann, E.; Woods, T. N.

2017-12-01

Understanding the effects of solar variability on planetary atmospheres has been hindered by the lack of accurate models and measurements of the soft x-ray (SXR) spectral irradiance (0-6 nm). Most measurements of the SXR have been broadband and are difficult to interpret due to changing spectral distribution under the pass band of the instruments. Models that use reference spectra for quiet sun, active region, and flaring contributions to irradiance have been made, but with limited success. The recent Miniature X-ray Solar Spectrometer (MinXSS) CubeSat made spectral measurements in the 0.04 - 3 nm range from June 2016 to May 2017, observing the Sun at many different levels of activity. In addition, the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) has observed the Sun since May 2010, in both broad bands (including a band at 0-7 nm) and spectrally resolved (6-105 nm at 0.1 nm resolution). We will present an improved model of the SXR based on new reference spectra from MinXSS and SDO-EVE. The non-flaring portion of the model is driven by broadband SXR measurements for determining activity level and relative contributions of quiet and active sun. Flares are modeled using flare temperatures from the GOES X-Ray Sensors. The improved SXR model can be driven by any sensors that provide a measure of activity level and flare temperature from any vantage point in the solar system. As an example, a version of the model is using the broadband solar irradiance measurements from the MAVEN EUV Monitor at Mars will be presented.

A bibliography on the search for extraterrestrial intelligence

NASA Technical Reports Server (NTRS)

Mallove, E. F.; Connors, M. M.; Forward, R. L.; Paprotny, Z.

1978-01-01

This report presents a uniform compilation of works dealing with the search for extraterrestrial intelligence. Entries are by first author, with cross-reference by topic index and by periodical index. This bibliography updates earlier bibliographies on this general topic while concentrating on research related to listening for signals from extraterrestrial intelligence.

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

NASA Technical Reports Server (NTRS)

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

2011-01-01

In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar

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

NASA Technical Reports Server (NTRS)

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

2008-01-01

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

Annually and monthly resolved solar irradiance and atmospheric temperature data across the Hawaiian archipelago from 1998 to 2015 with interannual summary statistics.

PubMed

Bryce, Richard; Losada Carreño, Ignacio; Kumler, Andrew; Hodge, Bri-Mathias; Roberts, Billy; Brancucci Martinez-Anido, Carlo

2018-08-01

This article contains data and summary statistics of solar irradiance and dry bulb temperature across the Hawaiian archipelago resolved on a monthly basis and spanning years 1998-2015. This data was derived in association with an article titled "Consequences of Neglecting the Interannual Variability of the Solar Resource: A Case Study of Photovoltaic Power Among the Hawaiian Islands" (Bryce et al., 2018 [7]). The solar irradiance data is presented in terms of Direct Normal Irradiance (DNI), Diffuse Horizontal Irradiance (DHI), and Global Horizontal Irradiance (GHI) and was obtained from the satellite-derived data contained in the National Solar Radiation Database (NSRDB). The temperature data is also obtained from this source. We have processed the NSRDB data and compiled these monthly resolved data sets, along with interannual summary statistics including the interannual coefficient of variability.

Alteration of Organic Compounds in Small Bodies and Cosmic Dusts by Cosmic Rays and Solar Radiation

NASA Astrophysics Data System (ADS)

Kobayashi, Kensei; Kaneko, Takeo; Mita, Hajime; Obayashi, Yumiko; Takahashi, Jun-ichi; Sarker, Palash K.; Kawamoto, Yukinori; Okabe, Takuto; Eto, Midori; Kanda, Kazuhiro

2012-07-01

A wide variety of complex organic compounds have been detected in extraterrestrial bodies like carbonaceous chondrites and comets, and their roles in the generation of terrestrial life are discussed. It was suggested that organics in small bodies were originally formed in ice mantles of interstellar dusts in dense cloud. Irradiation of frozen mixture of possible interstellar molecules including CO (or CH _{3}OH), NH _{3} and H _{2}O with high-energy particles gave complex amino acid precursors with high molecular weights [1]. Such complex organic molecules were taken in planetesimals or comets in the early solar system. In prior to the generation of the terrestrial life, extraterrestrial organics were delivered to the primitive Earth by such small bodies as meteorites, comets and space dusts. These organics would have been altered by cosmic rays and solar radiation (UV, X-rays) before the delivery to the Earth. We examined possible alteration of amino acids, their precursors and nucleic acid bases in interplanetary space by irradiation with high energy photons and heavy ions. A mixture of CO, NH _{3} and H _{2}O was irradiated with high-energy protons from a van de Graaff accelerator (TIT, Japan). The resulting products (hereafter referred to as CAW) are complex precursors of amino acids. CAW, amino acids (dl-Isovaline, glycine), hydantoins (amino acid precursors) and nucleic acid bases were irradiated with continuous emission (soft X-rays to IR; hereafter referred to as soft X-rays irradiation) from BL-6 of NewSUBARU synchrotron radiation facility (Univ. Hyogo). They were also irradiated with heavy ions (eg., 290 MeV/u C ^{6+}) from HIMAC accelerator (NIRS, Japan). After soft X-rays irradiation, water insoluble materials were formed. After irradiation with soft X-rays or heavy ions, amino acid precursors (CAW and hydantoins) gave higher ratio of amino acids were recovered after hydrolysis than free amino acids. Nucleic acid bases showed higher stability than free

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

NASA Astrophysics Data System (ADS)

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

2012-12-01

Integration of solar renewable energy into the power grid, like wind energy, is hindered by the variable nature of the solar resource. One challenge of the integration problem for shorter time periods is the phenomenon of "ramping events" where the electrical output of the solar power system increases or decreases significantly and rapidly over periods of minutes or less. Advance warning, of even just a few minutes, allows power system operators to compensate for the ramping. However, the ability for short-term prediction on such local "point" scales is beyond the abilities of typical model-based weather forecasting. Use of surface-based solar radiation measurements has been recognized as a likely solution for providing input for near-term (5 to 30 minute) forecasts of solar energy availability and variability. However, it must be noted that while fixed-orientation photovoltaic panel systems use the total (global) downwelling solar radiation, tracking photovoltaic and solar concentrator systems use only the direct normal component of the solar radiation. Thus even accurate near-term forecasts of total solar radiation will under many circumstances include inherent inaccuracies with respect to tracking systems due to lack of information of the direct component of the solar radiation. We will present examples and statistical analyses of solar radiation partitioning showing the differences in the behavior of the total/direct radiation with respect to the near-term forecast issue. We will present an overview of the possibility of using a network of unique new commercially available total/diffuse radiometers in conjunction with a near-real-time adaptation of the Shortwave Radiative Flux Analysis methodology (Long and Ackerman, 2000; Long et al., 2006). The results are used, in conjunction with persistence and tendency forecast techniques, to provide more accurate near-term forecasts of cloudiness, and both total and direct normal solar irradiance availability and

Microchip capillary electrophoresis instrumentation for in situ analysis in the search for extraterrestrial life.

PubMed

Mora, Maria F; Stockton, Amanda M; Willis, Peter A

2012-09-01

The search for signs of life on extraterrestrial planetary bodies is among NASA's top priorities in Solar System exploration. The associated pursuit of organics and biomolecules as evidence of past or present life demands in situ investigations of planetary bodies for which sample return missions are neither practical nor affordable. These in situ studies require instrumentation capable of sensitive chemical analyses of complex mixtures including a broad range of organic molecules. Instrumentation must also be capable of autonomous operation aboard a robotically controlled vehicle that collects data and transmits it back to Earth. Microchip capillary electrophoresis (μCE) coupled to laser-induced fluorescence (LIF) detection provides this required sensitivity and targets a wide range of relevant organics while offering low mass, volume, and power requirements. Thus, this technology would be ideally suited for in situ studies of astrobiology targets, such as Mars, Europa, Enceladus, and Titan. In this review, we introduce the characteristics of these planetary bodies that make them compelling destinations for extraterrestrial astrobiological studies, and the principal groups of organics of interest associated with each. And although the technology we describe here was first developed specifically for proposed studies of Mars, by summarizing its evolution over the past decade, we demonstrate how μCE-LIF instrumentation has become an ideal candidate for missions of exploration to all of these nearby worlds in our Solar System. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proposal and evaluation of subordinate standard solar irradiance spectra for applications in solar energy systems

DOE PAGES

Jessen, Wilko; Wilbert, Stefan; Gueymard, Christian A.; ...

2018-04-10

Reference solar irradiance spectra are needed to specify key parameters of solar technologies such as photovoltaic cell efficiency, in a comparable way. The IEC 60904-3 and ASTM G173 standards present such spectra for Direct Normal Irradiance (DNI) and Global Tilted Irradiance (GTI) on a 37 degrees tilted sun-facing surface for one set of clear-sky conditions with an air mass of 1.5 and low aerosol content. The IEC/G173 standard spectra are the widely accepted references for these purposes. Hence, the authors support the future replacement of the outdated ISO 9845 spectra with the IEC spectra within the ongoing update of thismore » ISO standard. The use of a single reference spectrum per component of irradiance is important for clarity when comparing and rating solar devices such as PV cells. However, at some locations the average spectra can differ strongly from those defined in the IEC/G173 standards due to widely different atmospheric conditions and collector tilt angles. Therefore, additional subordinate standard spectra for other atmospheric conditions and tilt angles are of interest for a rough comparison of product performance under representative field conditions, in addition to using the main standard spectrum for product certification under standard test conditions. This simplifies the product selection for solar power systems when a fully-detailed performance analysis is not feasible (e.g. small installations). Also, the effort for a detailed yield analyses can be reduced by decreasing the number of initial product options. After appropriate testing, this contribution suggests a number of additional spectra related to eight sets of atmospheric conditions and tilt angles that are currently considered within ASTM and ISO working groups. The additional spectra, called subordinate standard spectra, are motivated by significant spectral mismatches compared to the IEC/G173 spectra (up to 6.5%, for PV at 37 degrees tilt and 10-15% for CPV). These mismatches

Proposal and evaluation of subordinate standard solar irradiance spectra for applications in solar energy systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jessen, Wilko; Wilbert, Stefan; Gueymard, Christian A.

Reference solar irradiance spectra are needed to specify key parameters of solar technologies such as photovoltaic cell efficiency, in a comparable way. The IEC 60904-3 and ASTM G173 standards present such spectra for Direct Normal Irradiance (DNI) and Global Tilted Irradiance (GTI) on a 37 degrees tilted sun-facing surface for one set of clear-sky conditions with an air mass of 1.5 and low aerosol content. The IEC/G173 standard spectra are the widely accepted references for these purposes. Hence, the authors support the future replacement of the outdated ISO 9845 spectra with the IEC spectra within the ongoing update of thismore » ISO standard. The use of a single reference spectrum per component of irradiance is important for clarity when comparing and rating solar devices such as PV cells. However, at some locations the average spectra can differ strongly from those defined in the IEC/G173 standards due to widely different atmospheric conditions and collector tilt angles. Therefore, additional subordinate standard spectra for other atmospheric conditions and tilt angles are of interest for a rough comparison of product performance under representative field conditions, in addition to using the main standard spectrum for product certification under standard test conditions. This simplifies the product selection for solar power systems when a fully-detailed performance analysis is not feasible (e.g. small installations). Also, the effort for a detailed yield analyses can be reduced by decreasing the number of initial product options. After appropriate testing, this contribution suggests a number of additional spectra related to eight sets of atmospheric conditions and tilt angles that are currently considered within ASTM and ISO working groups. The additional spectra, called subordinate standard spectra, are motivated by significant spectral mismatches compared to the IEC/G173 spectra (up to 6.5%, for PV at 37 degrees tilt and 10-15% for CPV). These mismatches

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

NASA Astrophysics Data System (ADS)

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

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

Solar total irradiance in cycle 23

NASA Astrophysics Data System (ADS)

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

2011-05-01

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

Christian Soteriology and Extraterrestrial Intelligence

NASA Astrophysics Data System (ADS)

Weidemann, C.

The paper presents an argument for the incompatibility of classical Christian soteriology (doctrine of salvation) with belief in numerous extraterrestrial intelligent life forms (ETI). Four popular answers to the problem are discussed and rejected: a) unlike humanity, extraterrestrial intelligent species are not in need of salvation; b) Jesus of Nazareth has reconciled the entire cosmos to God; c) God or the second person of the Trinity has incarnated (or will incarnate) himself multiple times; d) alien sinners have been or are going to be saved by means different from a divine incarnation. The final section deals with remaining options for rational Christian believers and speculates briefly about consequences for interstellar space flight.

Study of extraterrestrial disposal of radioactive wastes. Part 2: Preliminary feasibility screening study of extraterrestrial disposal of radioactive wastes in concentrations, matrix materials, and containers designed for storage on earth

NASA Technical Reports Server (NTRS)

Hyland, R. E.; Wohl, M. L.; Thompson, R. L.; Finnegan, P. M.

1972-01-01

The results are reported of a preliminary feasibility screening study for providing long-term solutions to the problems of handling and managing radioactive wastes by extraterrestrial transportation of the wastes. Matrix materials and containers are discussed along with payloads, costs, and destinations for candidate space vehicles. The conclusions reached are: (1) Matrix material such as spray melt can be used without exceeding temperature limits of the matrix. (2) The cost in mills per kw hr electric, of space disposal of fission products is 4, 5, and 28 mills per kw hr for earth escape, solar orbit, and solar escape, respectively. (3) A major factor effecting cost is the earth storage time. Based on a normal operating condition design for solar escape, a storage time of more than sixty years is required to make the space disposal charge less than 10% of the bus-bar electric cost. (4) Based on a 10 year earth storage without further processing, the number of shuttle launches required would exceed one per day.

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

NASA Astrophysics Data System (ADS)

Bllbao, Julia; Román, Roberto; Miguel, Argimiro

2013-04-01

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

Curating NASA's Past, Present, and Future Extraterrestrial Sample Collections

NASA Technical Reports Server (NTRS)

McCubbin, F. M.; Allton, J. H.; Evans, C. A.; Fries, M. D.; Nakamura-Messenger, K.; Righter, K.; Zeigler, R. A.; Zolensky, M.; Stansbery, E. K.

2016-01-01

The Astromaterials Acquisition and Curation Office (henceforth referred to herein as NASA Curation Office) at NASA Johnson Space Center (JSC) is responsible for curating all of NASA's extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10E "Curation of Extraterrestrial Materials", JSC is charged with "...curation of all extra-terrestrial material under NASA control, including future NASA missions." The Directive goes on to define Curation as including "...documentation, preservation, preparation, and distribution of samples for research, education, and public outreach." Here we describe some of the past, present, and future activities of the NASA Curation Office.

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

NASA Technical Reports Server (NTRS)

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

2008-01-01

The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

Effects of Light and Electron Beam Irradiation on Halide Perovskites and Their Solar Cells.

PubMed

Klein-Kedem, Nir; Cahen, David; Hodes, Gary

2016-02-16

Hybrid alkylammonium lead halide perovskite solar cells have, in a very few years of research, exceeded a light-to-electricity conversion efficiency of 20%, not far behind crystalline silicon cells. These perovskites do not contain any rare element, the amount of toxic lead used is very small, and the cells can be made with a low energy input. They therefore already conform to two of the three requirements for viable, commercial solar cells-efficient and cheap. The potential deal-breaker is their long-term stability. While reasonable short-term (hours) and even medium term (months) stability has been demonstrated, there is concern whether they will be stable for the two decades or more expected from commercial cells in view of the intrinsically unstable nature of these materials. In particular, they have a tendency to be sensitive to various types of irradiation, including sunlight, under certain conditions. This Account focuses on the effect of irradiation on the hybrid (and to a small degree, all-inorganic) lead halide perovskites and their solar cells. It is split up into two main sections. First, we look at the effect of electron beams on the materials. This is important, since such beams are used for characterization of both the perovskites themselves and cells made from them (electron microscopy for morphological and compositional characterization; electron beam-induced current to study cell operation mechanism; cathodoluminescence for charge carrier recombination studies). Since the perovskites are sensitive to electron beam irradiation, it is important to minimize beam damage to draw valid conclusions from such measurements. The second section treats the effect of visible and solar UV irradiation on the perovskites and their cells. As we show, there are many such effects. However, those affecting the perovskite directly need not necessarily always be detrimental to the cells, while those affecting the solar cells, which are composed of several other phases

Technologies and Methods Used at the Laboratory for Atmospheric and Space Physics (LASP) to Serve Solar Irradiance Data

NASA Technical Reports Server (NTRS)

Pankratz, Chris; Beland, Stephane; Craft, James; Baltzer, Thomas; Wilson, Anne; Lindholm, Doug; Snow, Martin; Woods, Thomas; Woodraska, Don

2018-01-01

The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder, USA operates the Solar Radiation and Climate Experiment (SORCE) NASA mission, as well as several other NASA spacecraft and instruments. Dozens of Solar Irradiance data sets are produced, managed, and disseminated to the science community. Data are made freely available to the scientific immediately after they are produced using a variety of data access interfaces, including the LASP Interactive Solar Irradiance Datacenter (LISIRD), which provides centralized access to a variety of solar irradiance data sets using both interactive and scriptable/programmatic methods. This poster highlights the key technological elements used for the NASA SORCE mission ground system to produce, manage, and disseminate data to the scientific community and facilitate long-term data stewardship. The poster presentation will convey designs, technological elements, practices and procedures, and software management processes used for SORCE and their relationship to data quality and data management standards, interoperability, NASA data policy, and community expectations.

Messages from Space: The Solar System and Beyond. Grades 508. Teacher's Guide. Great Explorations in Science (GEMS).

ERIC Educational Resources Information Center

Beals, Kevin; Erickson, John; Sneider, Cary

Building on collaborative work between the Search for Extraterrestrial Intelligence (SETI) Institute and the Lawrence Hall of Science, this curriculum takes advantage of humans' fascination with extraterrestrials to catalyze the study of the solar system and beyond. The unit begins when students attempt to decode a fictitious message from outer…

Pros and cons in the search for extraterrestrial intelligence.

PubMed

Kantha, S S

1996-03-01

I propose a new term, 'galactic organism with distinct intelligence', for the extraterrestrial forms, with which humans can make contact. This is because, among the three existing terms: (a) 'the search for extraterrestrial intelligence' 'excludes biology and is inelegant'; (b) 'extraterrestrial' does not distinguish between the micro-organisms and highly-evolved intelligent life-forms; and (c) 'unidentified flying object' projects a sense of mysticism. On the presence of galactic organisms with distinct intelligence, scientists belong to three camps. Astronomers, physicists and some biochemists belong to the believers group. Evolutionists are in the doubters category. The third camp is represented by the 'uncommitted'. Approaches for contacting galactic organisms with distinct intelligence would take three steps. These are: (a) radioastronomical observations in the galaxy and interstellar space for the presence of organic matter; (b) initiating radio contact and listening to any transmitted message, as set out by the search for extraterrestrial intelligence program, and (c) landing instruments and humans in the galaxy.

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

PubMed Central

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

2008-01-01

There is a 5 W/m2 (about 0.35 %) difference between current on-orbit Total Solar Irradiance (TSI) measurements. On 18–20 July 2005, a workshop was held at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland that focused on understanding possible reasons for this difference, through an examination of the instrument designs, calibration approaches, and appropriate measurement equations. The instruments studied in that workshop included the Active Cavity Radiometer Irradiance Monitor III (ACRIM III) on the Active Cavity Radiometer Irradiance Monitor SATellite (ACRIMSAT), the Total Irradiance Monitor (TIM) on the Solar Radiation and Climate Experiment (SORCE), the Variability of solar IRradiance and Gravity Oscillations (VIRGO) on the Solar and Heliospheric Observatory (SOHO), and the Earth Radiation Budget Experiment (ERBE) on the Earth Radiation Budget Satellite (ERBS). Presentations for each instrument included descriptions of its design, its measurement equation and uncertainty budget, and the methods used to assess on-orbit degradation. The workshop also included a session on satellite- and ground-based instrument comparisons and a session on laboratory-based comparisons and the application of new laboratory comparison techniques. The workshop has led to investigations of the effects of diffraction and of aperture area measurements on the differences between instruments. In addition, a laboratory-based instrument comparison is proposed that uses optical power measurements (with lasers that underfill the apertures of the TSI instruments), irradiance measurements (with lasers that overfill the apertures of the TSI instrument), and a cryogenic electrical substitution radiometer as a standard for comparing the instruments. A summary of the workshop and an overview of the proposed research efforts are presented here. PMID:27096120

Recent concepts in missions to Mars - Extraterrestrial processes

NASA Technical Reports Server (NTRS)

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

1986-01-01

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

Random Forests (RFs) for Estimation, Uncertainty Prediction and Interpretation of Monthly Solar Potential

NASA Astrophysics Data System (ADS)

Assouline, Dan; Mohajeri, Nahid; Scartezzini, Jean-Louis

2017-04-01

Solar energy is clean, widely available, and arguably the most promising renewable energy resource. Taking full advantage of solar power, however, requires a deep understanding of its patterns and dependencies in space and time. The recent advances in Machine Learning brought powerful algorithms to estimate the spatio-temporal variations of solar irradiance (the power per unit area received from the Sun, W/m2), using local weather and terrain information. Such algorithms include Deep Learning (e.g. Artificial Neural Networks), or kernel methods (e.g. Support Vector Machines). However, most of these methods have some disadvantages, as they: (i) are complex to tune, (ii) are mainly used as a black box and offering no interpretation on the variables contributions, (iii) often do not provide uncertainty predictions (Assouline et al., 2016). To provide a reasonable solar mapping with good accuracy, these gaps would ideally need to be filled. We present here simple steps using one ensemble learning algorithm namely, Random Forests (Breiman, 2001) to (i) estimate monthly solar potential with good accuracy, (ii) provide information on the contribution of each feature in the estimation, and (iii) offer prediction intervals for each point estimate. We have selected Switzerland as an example. Using a Digital Elevation Model (DEM) along with monthly solar irradiance time series and weather data, we build monthly solar maps for Global Horizontal Irradiance (GHI), Diffuse Horizontal Irradiance (GHI), and Extraterrestrial Irradiance (EI). The weather data include monthly values for temperature, precipitation, sunshine duration, and cloud cover. In order to explain the impact of each feature on the solar irradiance of each point estimate, we extend the contribution method (Kuz'min et al., 2011) to a regression setting. Contribution maps for all features can then be computed for each solar map. This provides precious information on the spatial variation of the features impact all

Solar radiation measurement project

NASA Technical Reports Server (NTRS)

Ioup, J. W.

1981-01-01

The Xavier solar radiation measurement project and station are described. Measurements of the total solar radiation on a horizontal surface from an Eppley pyranometer were collected into computer data files. Total radiation in watt hours was converted from ten minute intervals to hourly intervals. Graphs of this total radiation data are included. A computer program in Fortran was written to calculate the total extraterrestrial radiation on a horizontal surface for each day of the month. Educational and social benefits of the project are cited.

Comparison of several databases of downward solar daily irradiation data at ocean surface with PIRATA measurements

NASA Astrophysics Data System (ADS)

Trolliet, Mélodie; Wald, Lucien

2017-04-01

The solar radiation impinging at sea surface is an essential variable in climate system. There are several means to assess the daily irradiation at surface, such as pyranometers aboard ship or on buoys, meteorological re-analyses and satellite-derived databases. Among the latter, assessments made from the series of geostationary Meteosat satellites offer synoptic views of the tropical and equatorial Atlantic Ocean every 15 min with a spatial resolution of approximately 5 km. Such Meteosat-derived databases are fairly recent and the quality of the estimates of the daily irradiation must be established. Efforts have been made for the land masses and must be repeated for the Atlantic Ocean. The Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) network of moorings in the Tropical Atlantic Ocean is considered as a reference for oceanographic data. It consists in 17 long-term Autonomous Temperature Line Acquisition System (ATLAS) buoys equipped with sensors to measure near-surface meteorological and subsurface oceanic parameters, including downward solar irradiation. Corrected downward solar daily irradiation from PIRATA were downloaded from the NOAA web site and were compared to several databases: CAMS RAD, HelioClim-1, HelioClim-3 v4 and HelioClim-3 v5. CAMS-RAD, the CAMS radiation service, combines products of the Copernicus Atmosphere Monitoring Service (CAMS) on gaseous content and aerosols in the atmosphere together with cloud optical properties deduced every 15 min from Meteosat imagery to supply estimates of the solar irradiation. Part of this service is the McClear clear sky model that provides estimates of the solar irradiation that should be observed in cloud-free conditions. The second and third databases are HelioClim-1 and HelioClim-3 v4 that are derived from Meteosat images using the Heliosat-2 method and the ESRA clear sky model, based on the Linke turbidity factor. HelioClim-3 v5 is the fourth database and differs from v4 by the

Statistical analysis of global horizontal solar irradiation GHI in Fez city, Morocco

NASA Astrophysics Data System (ADS)

Bounoua, Z.; Mechaqrane, A.

2018-05-01

An accurate knowledge of the solar energy reaching the ground is necessary for sizing and optimizing the performances of solar installations. This paper describes a statistical analysis of the global horizontal solar irradiation (GHI) at Fez city, Morocco. For better reliability, we have first applied a set of check procedures to test the quality of hourly GHI measurements. We then eliminate the erroneous values which are generally due to measurement or the cosine effect errors. Statistical analysis show that the annual mean daily values of GHI is of approximately 5 kWh/m²/day. Daily monthly mean values and other parameter are also calculated.

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

NASA Technical Reports Server (NTRS)

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

1988-01-01

AlGaAs/GaAs solar cells with an approximately 0.5-micron-thick Al(0.85)Ga(0.15)As window layer were irradiated using normal and isotropic incident protons having energies between 50 and 500 keV with fluence up to 1 x 10 to the 12th protons/sq cm. The irradiated cells were annealed at temperatures between 150 and 300 C in nitrogen ambient. The annealing results reveal that significant recovery in spectral response at longer wavelengths occurred. However, the short-wavelength spectral response showed negligible annealing, irrespective of the irradiation energy and annealing conditions. This indicates that the damage produced near the AlGaAs/GaAs interface and the space-charge region anneals differently than damage produced in the bulk. This is explained by using a model in which the as-grown dislocations interact with irradiation-induced point defects to produce thermally stable defects.

Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

NASA Technical Reports Server (NTRS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-01-01

Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

The Effect of Solar Irradiated Vibrio cholerae on the Secretion of Pro-Inflammatory Cytokines and Chemokines by the JAWS II Dendritic Cell Line In Vitro

PubMed Central

Ssemakalu, Cornelius Cano; Ubomba-Jaswa, Eunice; Motaung, Keolebogile Shirley; Pillay, Michael

2015-01-01

The use of solar irradiation to sterilize water prior to its consumption has resulted in the reduction of water related illnesses in waterborne disease endemic communities worldwide. Currently, research on solar water disinfection (SODIS) has been directed towards understanding the underlying mechanisms through which solar irradiation inactivates the culturability of microorganisms in water, enhancement of the disinfection process, and the health impact of SODIS water consumption. However, the immunological consequences of SODIS water consumption have not been explored. In this study, we investigated the effect that solar irradiated V. cholerae may have had on the secretion of cytokines and chemokines by the JAWS II dendritic cell line in vitro. The JAWS II dendritic cell line was stimulated with the different strains of V. cholerae that had been: (i) prepared in PBS, (ii) inactivated through a combination of heat and chemical, (iii) solar irradiated, and (iv) non-solar irradiated, in bottled water. As controls, LPS (1 μg/ml) and CTB (1 μg/ml) were used as stimulants. After 48 hours of stimulation the tissue culture media from each treatment was qualitatively and quantitatively analysed for the presence of IL-1α, IL-1β, IL-6, IL-7, IL-10, IL-12p40, IL-12p70, IL-15, MIP-1α, MIP-1β, MIP-2, RANTES, TNF-α, IL-23 and IL-27. Results showed that solar irradiated cultures of V. cholerae induced dendritic cells to secrete significant (p<0.05) levels of pro-inflammatory cytokines in comparison to the unstimulated dendritic cells. Furthermore, the amount of pro-inflammatory cytokines secreted by the dendritic cells in response to solar irradiated cultures of V. cholerae was not as high as observed in treatments involving non-solar irradiated cultures of V. cholerae or LPS. Our results suggest that solar irradiated microorganisms are capable of inducing the secretion of pro-inflammatory cytokines and chemokines. This novel finding is key towards understanding the

Uncertainty Model for Total Solar Irradiance Estimation on Australian Rooftops

NASA Astrophysics Data System (ADS)

Al-Saadi, Hassan; Zivanovic, Rastko; Al-Sarawi, Said

2017-11-01

The installations of solar panels on Australian rooftops have been in rise for the last few years, especially in the urban areas. This motivates academic researchers, distribution network operators and engineers to accurately address the level of uncertainty resulting from grid-connected solar panels. The main source of uncertainty is the intermittent nature of radiation, therefore, this paper presents a new model to estimate the total radiation incident on a tilted solar panel. Where a probability distribution factorizes clearness index, the model is driven upon clearness index with special attention being paid for Australia with the utilization of best-fit-correlation for diffuse fraction. The assessment of the model validity is achieved with the adoption of four goodness-of-fit techniques. In addition, the Quasi Monte Carlo and sparse grid methods are used as sampling and uncertainty computation tools, respectively. High resolution data resolution of solar irradiations for Adelaide city were used for this assessment, with an outcome indicating a satisfactory agreement between actual data variation and model.

Collected Extraterrestrial Materials: Constraints on Meteor and Fireball Compositions

NASA Astrophysics Data System (ADS)

Rietmeijer, Frans J. M.; Nuth, Joseph A., III

The bulk density and bulk porosity of IDPs and various meteorite classes show that protoplanet accretion and evolution were arrested at different stages as a function of parent body modification. The collected IDPs, micrometeorites and meteorites are aggregates of different structural entities that were inherited from the earliest times of solar system evolution. These structural entities and the extent of parent body lithification will determine the material strength of the meteoroids entering the Earth's atmosphere. There is a need for measurements of the material strength of collected extraterrestrial materials because they will in part determine the nature of the chemical interactions of descending meteors and fireballs in the atmosphere. High-precision determinations of meteor and fireball compositions are required to search for anhydrous, carbon-rich proto-CI material that has survived in the boulders of comet nuclei.

Spectral irradiance curve calculations for any type of solar eclipse

NASA Technical Reports Server (NTRS)

Deepak, A.; Merrill, J. E.

1974-01-01

A simple procedure is described for calculating the eclipse function (EF), alpha, and hence the spectral irradiance curve (SIC), (1-alpha), for any type of solar eclipse: namely, the occultation (partial/total) eclipse and the transit (partial/annular) eclipse. The SIC (or the EF) gives the variation of the amount (or the loss) of solar radiation of a given wavelength reaching a distant observer for various positions of the moon across the sun. The scheme is based on the theory of light curves of eclipsing binaries, the results of which are tabulated in Merrill's Tables, and is valid for all wavelengths for which the solar limb-darkening obeys the cosine law: J = sub c (1 - X + X cost gamma). As an example of computing the SIC for an occultation eclipse which may be total, the calculations for the March 7, 1970, eclipse are described in detail.

The Development of a New Model of Solar EUV Irradiance Variability

NASA Technical Reports Server (NTRS)

Warren, Harry; Wagner, William J. (Technical Monitor)

2002-01-01

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.

Using Global Total Electron Content to Understand Interminimum Changes in Solar EUV Irradiance and Thermospheric Composition

NASA Astrophysics Data System (ADS)

McDonald, S. E.; Emmert, J. T.; Krall, J.; Mannucci, A. J.; Vergados, P.

2017-12-01

To understand how and why the distribution of geospace plasma in the ionosphere/plasmasphere is evolving over multi-decadal time scales in response to solar, heliospheric and atmospheric forcing, it is critically important to have long-term, stable datasets. In this study, we use a newly constructed dataset of GPS-based total electron content (TEC) developed by JPL. The JPL Global Ionosphere Mapping (GIM) algorithm was used to generate a 35-station dataset spanning two solar minimum periods (1993-2014). We also use altimeter-derived TEC measurements from TOPEX-Poseidon and Jason-1 to construct a continuous dataset for the 1995-2014 time period. Both longterm datasets are compared to each other to study interminimum changes in the global TEC (during 1995-1995 and 2008-2009). We use the SAMI3 physics-based model of the ionosphere to compare the simulations of 1995-2014 with the JPL TEC and TOPEX/Jason-1 datasets. To drive SAMI3, we use the Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) model to specify the EUV irradiances, and NRLMSIS to specify the thermosphere. We adjust the EUV irradiances and thermospheric constituents to match the TEC datasets and draw conclusions regarding sources of the differences between the two solar minimum periods.

Direct-to-diffuse UV Solar Irradiance Ratio for a UV rotating Shadowband Spectroradiometer and a UV Multi-filter Rotating Shadowband Radiometer

NASA Astrophysics Data System (ADS)

Lantz, K.; Kiedron, P.; Petropavlovskikh, I.; Michalsky, J.; Slusser, J.

2008-12-01

. Two spectroradiometers reside that measure direct and diffuse UV solar irradiance are located at the Table Mountain Test Facility, 8 km north of Boulder, CO. The UV- Rotating Shadowband Spectrograph (UV-RSS) measures diffuse and direct solar irradiance from 290 - 400 nm. The UV Multi-Filter Rotating Shadowband Radiometer (UV-MFRSR) measures diffuse and direct solar irradiance in seven 2-nm wide bands, i.e. 300, 305, 311, 317, 325, and 368 nm. The purpose of the work is to compare radiative transfer model calculations (TUV) with the results from the UV-Rotating Shadowband Spectroradiometer (UV-RSS) and the UV-MFRSR to estimate direct-to-diffuse solar irradiance ratios (DDR) that are used to evaluate the possibility of retrieving aerosol single scattering albedo (SSA) under a variety of atmospheric conditions: large and small aerosol loading, large and small surface albedo. For the radiative transfer calculations, total ozone measurements are obtained from a collocated Brewer spectrophotometer.

A Global Solar Irradiance Climatology of an Intermountain Region.

DTIC Science & Technology

1986-01-01

D-A!171 97 A GLOBAL SOLAIR IRRRDIANCE CLIMATOLOGY OF AN INTERMOUNTAIN REGION(U) AIR FORCE INST OF TECH MRIGHT-PATTERSON APR ON E W DOBRY 1986...DD~ I JAN 73 1473 EDITION OF I NOV 65 IS OBSOLETE SECURITY CLASSIFICATION OF THIS PAGE Denfata E1ilered) %.ir.. , t . ~. ~ ~ ~ $~:V ( e vis ABSTRACT...Professor: Dr. G. E . Bingham De artment: Soil Science and Biometeorology A global solar irradiance climatology of an intermountain region is developed using

The use of satellite data assimilation methods in regional NWP for solar irradiance forecasting

NASA Astrophysics Data System (ADS)

Kurzrock, Frederik; Cros, Sylvain; Chane-Ming, Fabrice; Potthast, Roland; Linguet, Laurent; Sébastien, Nicolas

2016-04-01

As an intermittent energy source, the injection of solar power into electricity grids requires irradiance forecasting in order to ensure grid stability. On time scales of more than six hours ahead, numerical weather prediction (NWP) is recognized as the most appropriate solution. However, the current representation of clouds in NWP models is not sufficiently precise for an accurate forecast of solar irradiance at ground level. Dynamical downscaling does not necessarily increase the quality of irradiance forecasts. Furthermore, incorrectly simulated cloud evolution is often the cause of inaccurate atmospheric analyses. In non-interconnected tropical areas, the large amplitudes of solar irradiance variability provide abundant solar yield but present significant problems for grid safety. Irradiance forecasting is particularly important for solar power stakeholders in these regions where PV electricity penetration is increasing. At the same time, NWP is markedly more challenging in tropic areas than in mid-latitudes due to the special characteristics of tropical homogeneous convective air masses. Numerous data assimilation methods and strategies have evolved and been applied to a large variety of global and regional NWP models in the recent decades. Assimilating data from geostationary meteorological satellites is an appropriate approach. Indeed, models converting radiances measured by satellites into cloud properties already exist. Moreover, data are available at high temporal frequencies, which enable a pertinent cloud cover evolution modelling for solar energy forecasts. In this work, we present a survey of different approaches which aim at improving cloud cover forecasts using the assimilation of geostationary meteorological satellite data into regional NWP models. Various approaches have been applied to a variety of models and satellites and in different regions of the world. Current methods focus on the assimilation of cloud-top information, derived from infrared

Estimation of atmospheric turbidity and surface radiative parameters using broadband clear sky solar irradiance models in Rio de Janeiro-Brasil

NASA Astrophysics Data System (ADS)

Flores, José L.; Karam, Hugo A.; Marques Filho, Edson P.; Pereira Filho, Augusto J.

2016-02-01

The main goal of this paper is to estimate a set of optimal seasonal, daily, and hourly values of atmospheric turbidity and surface radiative parameters Ångström's turbidity coefficient ( β), Ångström's wavelength exponent ( α), aerosol single scattering albedo ( ω o ), forward scatterance ( F c ) and average surface albedo ( ρ g ), using the Brute Force multidimensional minimization method to minimize the difference between measured and simulated solar irradiance components, expressed as cost functions. In order to simulate the components of short-wave solar irradiance (direct, diffuse and global) for clear sky conditions, incidents on a horizontal surface in the Metropolitan Area of Rio de Janeiro (MARJ), Brazil (22° 51' 27″ S, 43° 13' 58″ W), we use two parameterized broadband solar irradiance models, called CPCR2 and Iqbal C, based on synoptic information. The meteorological variables such as precipitable water ( u w ) and ozone concentration ( u o ) required by the broadband solar models were obtained from moderate-resolution imaging spectroradiometer (MODIS) sensor on Terra and Aqua NASA platforms. For the implementation and validation processes, we use global and diffuse solar irradiance data measured by the radiometric platform of LabMiM, located in the north area of the MARJ. The data were measured between the years 2010 and 2012 at 1-min intervals. The performance of solar irradiance models using optimal parameters was evaluated with several quantitative statistical indicators and a subset of measured solar irradiance data. Some daily results for Ångström's wavelength exponent α were compared with Ångström's parameter (440-870 nm) values obtained by aerosol robotic network (AERONET) for 11 days, showing an acceptable level of agreement. Results for Ångström's turbidity coefficient β, associated with the amount of aerosols in the atmosphere, show a seasonal pattern according with increased precipitation during summer months (December

The search for extraterrestrial intelligence: Telecommunications technology

NASA Technical Reports Server (NTRS)

Edelson, R. E.; Levy, G. S.

1980-01-01

Efforts to discover evidence of intelligent extraterrestrial life have become not only feasible, but respectable. Fledgling observational projects have begun that will use state-of-the-art hardware to develop sophisticated receiving and data processing systems. The rationale behind the Search for Extraterrestrial Intelligence, the manner in which the program is taking shape, and the implications for telecommunications are described. It is concluded that the breadth of technological development required for the detection of signals from galactic brethren has particular relevance for the future of telecommunications in Earth oriented uses.

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

NASA Technical Reports Server (NTRS)

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

1975-01-01

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

On the plurality of inhabited worlds: a brief history of extraterrestrialism

NASA Astrophysics Data System (ADS)

Brake, Mark

2006-10-01

This paper delineates the cultural evolution of the ancient idea of a plurality of inhabited worlds, and traces its development through to contemporary extraterrestrialism, with its foundation in the physical determinism of cosmology, and its attendant myths of alien contact drawn from examples of British film and fiction. We shall see that, in the evolving debate of the existence of extraterrestrial life and intelligence, science and science fiction have benefited from an increasingly symbiotic relationship. Modern extraterrestrialism has influenced both the scientific searches for extraterrestrial intelligence (SETI), and become one of the most pervasive cultural myths of the 20th century. Not only has pluralism found a voice in fiction through the alien, but fiction has also inspired science to broach questions in the real world.

At what wavelengths should we search for signals from extraterrestrial intelligence? (SETI/infrared communication/interstellar communication/extraterrestrial intelligence)

NASA Technical Reports Server (NTRS)

Townes, C. H.

1979-01-01

Searches for extraterrestrial intelligence concentrate on attempts to receive signals in the microwave region, the argument being given that communication occurs there at minimum broadcasted power. Such a conclusion is shown to result only under a restricted set of assumptions. If generalized types of detection are considered, in particular photon detection rather than linear detection alone, and if advantage is taken of the directivity of telescopes at short wavelengths, then somewhat less power is required for communication at infrared wavelengths than in the microwave region. Furthermore, a variety of parameters other than power alone can be chosen for optimization by an extraterrestrial civilization.

Pioneer-Venus Press Clip. [Solar System formation and extraterrestrial life

NASA Technical Reports Server (NTRS)

1988-01-01

This video shows, with high quality animation, the formation of the Solar System: comets, Jupiter, Europa, Saturn, Titan, Mars, the Sun, and early Earth. The focus is on life elsewhere in the Solar System. The recording was prepared for a news conference.

Carbon arc solar simulator.

PubMed

Olson, R A; Parker, J H

1991-04-01

Measurements of the spatial, spectral, and temporal characteristics of the beam irradiance of a carbon arc solar simulator are reported. Pyroelectric radiometer measurements of total irradiance and spectroradiometer measurements of spectral irradiance are presented. The solar simulator spectral irradiance is compared with the ASTM standard AM 1.5 global solar spectral irradiance over a wavelength region of 300-2500 nm. The suitability of the solar simulator for laser receiver testing is discussed.

How Will We React to the Discovery of Extraterrestrial Life?

PubMed

Kwon, Jung Yul; Bercovici, Hannah L; Cunningham, Katja; Varnum, Michael E W

2017-01-01

How will humanity react to the discovery of extraterrestrial life? Speculation on this topic abounds, but empirical research is practically non-existent. We report the results of three empirical studies assessing psychological reactions to the discovery of extraterrestrial life using the Linguistic Inquiry and Word Count (LIWC) text analysis software. We examined language use in media coverage of past discovery announcements of this nature, with a focus on extraterrestrial microbial life (Pilot Study). A large online sample ( N = 501) was asked to write about their own and humanity's reaction to a hypothetical announcement of such a discovery (Study 1), and an independent, large online sample ( N = 256) was asked to read and respond to a newspaper story about the claim that fossilized extraterrestrial microbial life had been found in a meteorite of Martian origin (Study 2). Across these studies, we found that reactions were significantly more positive than negative, and more reward vs. risk oriented. A mini-meta-analysis revealed large overall effect sizes (positive vs. negative affect language: g = 0.98; reward vs. risk language: g = 0.81). We also found that people's forecasts of their own reactions showed a greater positivity bias than their forecasts of humanity's reactions (Study 1), and that responses to reading an actual announcement of the discovery of extraterrestrial microbial life showed a greater positivity bias than responses to reading an actual announcement of the creation of man-made synthetic life (Study 2). Taken together, this work suggests that our reactions to a future confirmed discovery of microbial extraterrestrial life are likely to be fairly positive.

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

NASA Technical Reports Server (NTRS)

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

1995-01-01

When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

Photocarrier Radiometry for Non-contact Evaluation of Monocrystalline Silicon Solar Cell Under Low-Energy (< 200 keV) Proton Irradiation

NASA Astrophysics Data System (ADS)

Oliullah, Md.; Liu, J. Y.; Song, P.; Wang, Y.

2018-06-01

A three-layer theoretical model is developed for the characterization of the electronic transport properties (lifetime τ, diffusion coefficient D, and surface recombination velocity s) with energetic particle irradiation on solar cells using non-contact photocarrier radiometry. Monte Carlo (MC) simulation is carried out to obtain the depth profiles of the proton irradiation layer at different low energies (< 200 keV). The monocrystalline silicon (c-Si) solar cells are investigated under different low-energy proton irradiation, and the carrier transport parameters of the three layers are obtained by best-fitting of the experimental results. The results show that the low-energy protons have little influence on the transport parameters of the non-irradiated layer, but high influences on both of the p and n-region irradiation layers which are consisted of MC simulation.

Extraterrestrial Organic Compounds in Meteorites

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

SEARCH FOR EXTRATERRESTRIAL ANTINEUTRINO SOURCES WITH THE KamLAND DETECTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gando, A.; Gando, Y.; Ichimura, K.

2012-02-01

We present the results of a search for extraterrestrial electron antineutrinos ({nu}-bar{sub e}'s) in the energy range 8.3 MeV < E{sub {nu}}-bar{sub e} < 31.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of {sup 8}B solar {nu}{sub e}'s converting into {nu}-bar{sub e}'s at 5.3 Multiplication-Sign 10{sup -5} (90% CL), if we assume an undistorted {nu}-bar{sub e} shape. This limit corresponds to a solar {nu}-bar{sub e} flux ofmore » 93 cm{sup -2} s{sup -1} or an event rate of 1.6 events (kton - year){sup -1} above the energy threshold (E{sub {nu}}-bar{sub e}>=8.3 MeV). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.« less

The search for extra-terrestrial intelligence.

PubMed

Drake, Frank

2011-02-13

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.

Advancing Solar Irradiance Measurement for Climate-Related Studies: Accurate Constraint on Direct Aerosol Radiative Effect (DARE)

NASA Technical Reports Server (NTRS)

Tsay, Si-Chee; Ji, Q. Jack

2011-01-01

Earth's climate is driven primarily by solar radiation. As summarized in various IPCC reports, the global average of radiative forcing for different agents and mechanisms, such as aerosols or CO2 doubling, is in the range of a few W/sq m. However, when solar irradiance is measured by broadband radiometers, such as the fleet of Eppley Precision Solar Pyranometers (PSP) and equivalent instrumentation employed worldwide, the measurement uncertainty is larger than 2% (e.g., WMO specification of pyranometer, 2008). Thus, out of the approx. 184 W/sq m (approx.263 W/sq m if cloud-free) surface solar insolation (Trenberth et al. 2009), the measurement uncertainty is greater than +/-3.6 W/sq m, overwhelming the climate change signals. To discern these signals, less than a 1 % measurement uncertainty is required and is currently achievable only by means of a newly developed methodology employing a modified PSP-like pyranometer and an updated calibration equation to account for its thermal effects (li and Tsay, 2010). In this talk, we will show that some auxiliary measurements, such as those from a collocated pyrgeometer or air temperature sensors, can help correct historical datasets. Additionally, we will also demonstrate that a pyrheliometer is not free of the thermal effect; therefore, comparing to a high cost yet still not thermal-effect-free "direct + diffuse" approach in measuring surface solar irradiance, our new method is more economical, and more likely to be suitable for correcting a wide variety of historical datasets. Modeling simulations will be presented that a corrected solar irradiance measurement has a significant impact on aerosol forcing, and thus plays an important role in climate studies.

Correlations between variations in solar EUV and soft X-ray irradiance and photoelectron energy spectra observed on Mars and Earth

NASA Astrophysics Data System (ADS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-11-01

extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.

Possible extraterrestrial strategy for earth

NASA Astrophysics Data System (ADS)

Deardorff, J. W.

1986-03-01

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

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

NASA Technical Reports Server (NTRS)

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

1975-01-01

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

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)

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

2011-09-01

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.

Shortwave Radiometer Calibration Methods Comparison and Resulting Solar Irradiance Measurement Differences: A User Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habte, Aron; Sengupta, Manajit; Andreas, Afshin

Banks financing solar energy projects require assurance that these systems will produce the energy predicted. Furthermore, utility planners and grid system operators need to understand the impact of the variable solar resource on solar energy conversion system performance. Accurate solar radiation data sets reduce the expense associated with mitigating performance risk and assist in understanding the impacts of solar resource variability. The accuracy of solar radiation measured by radiometers depends on the instrument performance specification, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methods provided by radiometric calibrationmore » service providers, such as NREL and manufacturers of radiometers, on the resulting calibration responsivity. Some of these radiometers are calibrated indoors and some outdoors. To establish or understand the differences in calibration methodology, we processed and analyzed field-measured data from these radiometers. This study investigates calibration responsivities provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The BORCAL method provides the outdoor calibration responsivity of pyranometers and pyrheliometers at 45 degree solar zenith angle, and as a function of solar zenith angle determined by clear-sky comparisons with reference irradiance. The BORCAL method also employs a thermal offset correction to the calibration responsivity of single-black thermopile detectors used in pyranometers. Indoor calibrations of radiometers by their manufacturers are performed using a stable artificial light source in a side-by-side comparison between the test radiometer under calibration and a reference radiometer of the same type. In both methods, the reference radiometer calibrations are traceable to the World Radiometric Reference (WRR). These

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

USGS Publications Warehouse

Perry, C.A.

2006-01-01

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

How Will We React to the Discovery of Extraterrestrial Life?

PubMed Central

Kwon, Jung Yul; Bercovici, Hannah L.; Cunningham, Katja; Varnum, Michael E. W.

2018-01-01

How will humanity react to the discovery of extraterrestrial life? Speculation on this topic abounds, but empirical research is practically non-existent. We report the results of three empirical studies assessing psychological reactions to the discovery of extraterrestrial life using the Linguistic Inquiry and Word Count (LIWC) text analysis software. We examined language use in media coverage of past discovery announcements of this nature, with a focus on extraterrestrial microbial life (Pilot Study). A large online sample (N = 501) was asked to write about their own and humanity’s reaction to a hypothetical announcement of such a discovery (Study 1), and an independent, large online sample (N = 256) was asked to read and respond to a newspaper story about the claim that fossilized extraterrestrial microbial life had been found in a meteorite of Martian origin (Study 2). Across these studies, we found that reactions were significantly more positive than negative, and more reward vs. risk oriented. A mini-meta-analysis revealed large overall effect sizes (positive vs. negative affect language: g = 0.98; reward vs. risk language: g = 0.81). We also found that people’s forecasts of their own reactions showed a greater positivity bias than their forecasts of humanity’s reactions (Study 1), and that responses to reading an actual announcement of the discovery of extraterrestrial microbial life showed a greater positivity bias than responses to reading an actual announcement of the creation of man-made synthetic life (Study 2). Taken together, this work suggests that our reactions to a future confirmed discovery of microbial extraterrestrial life are likely to be fairly positive. PMID:29367849

Euhedral metallic-Fe-Ni grains in extraterrestrial samples

NASA Technical Reports Server (NTRS)

Rubin, Alan E.

1993-01-01

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

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)

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

2013-04-01

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

The Ethical Implications for Discovery of Extraterrestrial Life

NASA Astrophysics Data System (ADS)

Stuart, Jill

2012-05-01

Ethical frameworks seek to normatively structure our behaviour and preconstitute expectations with regards to moral activity towards each other as well as other creatures and even non-sentient objects such as the environment. This paper considers how ongoing ethical discussions relating to earth-based interactions can be used as analogies to inform nascent conversations about potential future encounters with extraterrestrial life—while also highlighting where these geocentric conversations may fail to capture the unique dynamics of potential extraterrestrial encounters. The paper specifically considers the spectrum of ethical frameworks currently used in earth-based interactions and how they might apply outside the geocentric referent; from ethics towards non- sentient life on earth such as plants and the environment; to ethics towards sentient but ‘unintelligent' life; to intelligent life nonetheless deemed less intelligent than humans. Next the paper considers interactions that we have yet to (knowingly) have encountered here on earth: the ethics of interactions with life more intelligent than ourselves; and finally the ethics of interaction with robotic ‘post-biological' forms, which some specialists in extraterrestrial communications have speculated will likely be the form of ‘creatures' to be encountered should contact with extraterrestrials ever be made. Finally the paper will address deeper philosophical-ethical questions about the significance of such an exercise in shifting ethical frameworks from an anthropocentric perspective.

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

NASA Technical Reports Server (NTRS)

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

2002-01-01

An earlier study compared NASA/NSO Spectromagnetograph (SPM) data with spacecraft measurements of total solar irradiance (TSI) variations over a 1.5 year period in the declining phase of solar cycle 22. This paper extends the analysis to an eight-year period which also spans the rising and early maximum phases of cycle 23. The conclusions of the earlier work appear to be robust: three factors (sunspots, strong unipolar regions, and strong mixed polarity regions) describe most of the variation in the SPM record, but only the first two are associated with TSI. Additionally, the residuals of a linear multiple regression of TSI against SPM observations over the entire eight-year period show an unexplained, increasing, linear time variation with a rate of about 0.05 W m(exp -2) per year. Separate regressions for the periods before and after 1996 January 01 show no unexplained trends but differ substantially in regression parameters. This behavior may reflect a solar source of TSI variations beyond sunspots and faculae but more plausibly results from uncompensated non-solar effects in one or both of the TSI and SPM data sets.

Investigation on the Maximum Power Point in Solar Panel Characteristics Due to Irradiance Changes

NASA Astrophysics Data System (ADS)

Abdullah, M. A.; Fauziah Toha, Siti; Ahmad, Salmiah

2017-03-01

One of the disadvantages of the photovoltaic module as compared to other renewable resources is the dynamic characteristics of solar irradiance due to inconsistency weather condition and surrounding temperature. Commonly, a photovoltaic power generation systems consist of an embedded control system to maximize the power generation due to the inconsistency in irradiance. In order to improve the simplicity of the power optimization control, this paper present the characteristic of Maximum Power Point with various irradiance levels for Maximum Power Point Tracking (MPPT). The technique requires a set of data from photovoltaic simulation model to be extrapolated as a standard relationship between irradiance and maximum power. The result shows that the relationship between irradiance and maximum power can be represented by a simplified quadratic equation. The first section in your paper

Implications of extraterrestrial material on the origin of life

NASA Astrophysics Data System (ADS)

Pasek, Matthew A.

Meteoritic organic material may provide the best perspective on prebiotic chemistry. Meteorites have also been invoked as a source of prebiotic material. This study suggests a caveat to extraterrestrial organic delivery: that prebiotic meteoritic organics were too dilute to promote prebiotic reactions. However, meteoritic material provides building material for endogenous synthesis of prebiotic molecules, such as by hydrolysis of extraterrestrial organic tars, and corrosion of phosphide minerals.

Search for extraterrestrial intelligence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrison, P.; Billingham, J.; Wolfe, J.

1979-01-01

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

Intensification of depolymerization of polyacrylic acid solution using different approaches based on ultrasound and solar irradiation with intensification studies.

PubMed

Prajapat, Amrutlal L; Gogate, Parag R

2016-09-01

Depolymerization of polyacrylic acid (PAA) as sodium salt has been investigated using ultrasonic and solar irradiations with process intensification studies based on combination with hydrogen peroxide (H2O2) and ozone (O3). Effect of solar intensity, ozone flow and ultrasonic power dissipation on the extent of viscosity reduction has been investigated for individual treatment approaches. The combined approaches such as US+solar, solar+O3, solar+H2O2, US+H2O2 and US+O3 have been subsequently investigated under optimum conditions and established to be more efficient as compared to individual approaches. Approach based on US (60W)+solar+H2O2 (0.01%) resulted in the maximum extent of viscosity reduction as 98.97% in 35min whereas operation of solar+H2O2 (0.01%), US (60W), H2O2 (0.3%) and solar irradiation resulted in about 98.08%, 90.13%, 8.91% and 90.77% intrinsic viscosity reduction in 60min respectively. Approach of US (60W)+solar+ozone (400mg/h flow rate) resulted in extent of viscosity reduction as 99.47% in 35min whereas only ozone (400mg/h flow rate), ozone (400mg/h flow rate)+US (60W) and ozone (400mg/h flow rate)+solar resulted in 69.04%, 98.97% and 98.51% reduction in 60min, 55min and 55min respectively. The chemical identity of the treated polymer using combined approaches was also characterized using FTIR (Fourier transform infrared) spectra and it was established that no significant structural changes were obtained during the treatment. Overall, it can be said that the combination technique based on US and solar irradiations in the presence of hydrogen peroxide is the best approach for the depolymerization of PAA solution. Copyright © 2016 Elsevier B.V. All rights reserved.

The development of extraterrestrial civilizations and physical laws

NASA Astrophysics Data System (ADS)

Troitskii, V. S.

Consideration is given to the limiting characteristics of extraterrestrial civilizations as allowed by physical laws, and to the possible pathways and levels of development of such civilizations. The concept of an extraterrestrial civilization is defined in terms of the exchange of information, energy and matter both within a community of intelligent beings and between the community and its environment. The possible characteristics of such a civilization are then examined, including amount of populated space, population and population density, energy requirements and supply, information content, transportation capacity and lifetimes, and it is shown that the space occupiable by an extraterrestrial civilization is limited to the space around its star, due to the finite velocity of transport processes. The development of a type II civilization, making use of energy on the order of that put out by its star, is then examined, and constraints on energy production in such a civilization making impossible the establishment of an omnidirectional radio beacon detectable throughout the Galaxy are pointed out.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halthore, R.N.; Schwartz, S.E.; Michalsky, J.J.

1997-03-01

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 themore » 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.« less

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

NASA Technical Reports Server (NTRS)

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

1997-01-01

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.

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

NASA Technical Reports Server (NTRS)

Chen, LI; Brasseur, Guy; London, Julius

1994-01-01

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

A study of extraterrestrial antineutrino sources with the KamLAND detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

The KamLAND Collaboration; Gando, A.; Gando, Y.

2011-05-18

We present the results of a search for extraterrestrial electron antineutrinos ({bar {nu}}{sub e}'s) in the energy range 8.3 MeV < E{sub {bar {nu}}}{sub e} < 30.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of {sup 8}B solar {nu}{sub e}'s converting into {bar {nu}}{sub e}'s at 5.3 x 10{sup -5} (90% C.L.). The present data also allows us to set more stringent limits on the diffuse supernovamore » neutrino flux and on the annihilation rates for light dark matter particles.« less

Nucleobases and Other Prebiotic Species from the UV Irradiation of Pyrimidine in Astrophysical Ices

NASA Technical Reports Server (NTRS)

Sandford, Scott; Materese, Christopher; Nuevo, Michel

2012-01-01

Nucleobases are aromatic N-heterocycles that constitute the informational subunits of DNA and RNA and are divided into two families: pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in meteorites and their extraterrestrial origin confirmed by isotope measurement. Although no N-heterocycles have been individually identified in the ISM, the 6.2-micron interstellar emission feature seen towards many astronomical objects suggests a population of such molecules is likely present. We report on a study of the formation of pyrimidine-based molecules, including nucleobases and other species of prebiotic interest, from the ultraviolet (UV) irradiation of pyrimidine in low temperature ices containing H2O, NH3, C3OH, and CH4, to simulate the astrophysical conditions under which prebiotic species may be formed in the Solar System.

Man and his spaceships: Vehicles for extraterrestrial colonization?

PubMed

Siefert, Janet L

2012-11-01

The resiliency and adaptive ability of microbial life in real time on Earth relies heavily upon horizontal gene transfer. Based on that knowledge, how likely is earth based microbial life to colonize extraterrestrial targets such as Mars? To address this question, we consider manned and unmanned space exploration, the resident microbiota that is likely to inhabit those vehicles, the adaptive potential of that microbiota in an extraterrestrial setting especially with regards to mobile genetic elements, and the likelihood that Mars like environments could initiate and sustain colonization.

Preservation of extraterrestrial 3He in 480-Ma-old marine limestones.