WorldWideScience

Sample records for net solar flux

  1. Aeronet Solar Flux

    Data.gov (United States)

    National Aeronautics and Space Administration — SolRad-Net (Solar Radiation Network) is an established network of ground-based sensors providing high-frequency solar flux measurements in quasi-realtime to the...

  2. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  3. The effect of Arctic sea-ice extent on the absorbed (net solar flux at the surface, based on ISCCP-D2 cloud data for 1983–2007

    Directory of Open Access Journals (Sweden)

    C. Matsoukas

    2010-01-01

    Full Text Available We estimate the effect of the Arctic sea ice on the absorbed (net solar flux using a radiative transfer model. Ice and cloud input data to the model come from satellite observations, processed by the International Satellite Cloud Climatology Project (ISCCP and span the period July 1983–June 2007. The sea-ice effect on the solar radiation fluctuates seasonally with the solar flux and decreases interannually in synchronisation with the decreasing sea-ice extent. A disappearance of the Arctic ice cap during the sunlit period of the year would radically reduce the local albedo and cause an annually averaged 19.7 W m−2 increase in absorbed solar flux at the Arctic Ocean surface, or equivalently an annually averaged 0.55 W m−2 increase on the planetary scale. In the clear-sky scenario these numbers increase to 34.9 and 0.97 W m−2, respectively. A meltdown only in September, with all other months unaffected, increases the Arctic annually averaged solar absorption by 0.32 W m−2. We examined the net solar flux trends for the Arctic Ocean and found that the areas absorbing the solar flux more rapidly are the North Chukchi and Kara Seas, Baffin and Hudson Bays, and Davis Strait. The sensitivity of the Arctic absorbed solar flux on sea-ice extent and cloud amount was assessed. Although sea ice and cloud affect jointly the solar flux, we found little evidence of strong non-linearities.

  4. Sol-Rad Net Flux (L 1.0, 1.5, 2.0)

    Data.gov (United States)

    National Aeronautics and Space Administration — SolRad-Net (Solar Radiation Network) is an established network of ground-based sensors providing high-frequency solar flux measurements in quasi-realtime to the...

  5. Solar Indices - Solar Radio Flux

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  6. GALILEO PROBE NET FLUX RADIOMETER DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Galileo Probe Net Flux Radiometer (NFR) measured net and upward radiation fluxes in Jupiter's atmosphere between about 0.44 bars and 14 bars, using five spectral...

  7. High-flux solar photon processes

    Energy Technology Data Exchange (ETDEWEB)

    Lorents, D C; Narang, S; Huestis, D C; Mooney, J L; Mill, T; Song, H K; Ventura, S [SRI International, Menlo Park, CA (United States)

    1992-06-01

    This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

  8. Periods of High Intensity Solar Proton Flux

    Science.gov (United States)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

    2012-01-01

    Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  9. Thermal net flux measurements on the Pioneer Venus entry probes

    Science.gov (United States)

    Revercomb, H. E.; Sromovsky, L. A.; Suomi, V. E.; Boese, R. W.

    1985-01-01

    Corrected thermal net (upward minus downward flux) radiation data from four Pioneer Venus probes at latitudes of 4 deg and 60 deg N, and 27 deg and 31 deg S, are presented. Comparisons of these fluxes with radiative transfer calculations were interpreted in terms of cloud properties and the global distribution of water vapor in the lower atmosphere of Venus. The presence of an as yet undetected source of IR opacity is implied by the fluxes in the upper cloud range. It was also shown that beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and a decrease of the water vapor mixing ratios toward the equator.

  10. Net carbon flux in organic and conventional olive production systems

    Science.gov (United States)

    Saeid Mohamad, Ramez; Verrastro, Vincenzo; Bitar, Lina Al; Roma, Rocco; Moretti, Michele; Chami, Ziad Al

    2014-05-01

    Agricultural systems are considered as one of the most relevant sources of atmospheric carbon. However, agriculture has the potentiality to mitigate carbon dioxide mainly through soil carbon sequestration. Some agricultural practices, particularly fertilization and soil management, can play a dual role in the agricultural systems regarding the carbon cycle contributing to the emissions and to the sequestration process in the soil. Good soil and input managements affect positively Soil Organic Carbon (SOC) changes and consequently the carbon cycle. The present study aimed at comparing the carbon footprint of organic and conventional olive systems and to link it to the efficiency of both systems on carbon sequestration by calculating the net carbon flux. Data were collected at farm level through a specific and detailed questionnaire based on one hectare as a functional unit and a system boundary limited to olive production. Using LCA databases particularly ecoinvent one, IPCC GWP 100a impact assessment method was used to calculate carbon emissions from agricultural practices of both systems. Soil organic carbon has been measured, at 0-30 cm depth, based on soil analyses done at the IAMB laboratory and based on reference value of SOC, the annual change of SOC has been calculated. Substracting sequestrated carbon in the soil from the emitted on resulted in net carbon flux calculation. Results showed higher environmental impact of the organic system on Global Warming Potential (1.07 t CO2 eq. yr-1) comparing to 0.76 t CO2 eq. yr-1 in the conventional system due to the higher GHG emissions caused by manure fertilizers compared to the use of synthetic foliar fertilizers in the conventional system. However, manure was the main reason behind the higher SOC content and sequestration in the organic system. As a resultant, the organic system showed higher net carbon flux (-1.7 t C ha-1 yr-1 than -0.52 t C ha-1 yr-1 in the conventional system reflecting higher efficiency as a

  11. Ozone flux over a Norway spruce forest and correlation with net ecosystem production

    Energy Technology Data Exchange (ETDEWEB)

    Zapletal, Milos, E-mail: milos.zapletal@ekotoxa.cz [Ekotoxa s.r.o. - Centre for Environment and Land Assessment, Oticka 37, 746 01 Opava (Czech Republic); Silesian University at Opava, Faculty of Philosophy and Science, Masarykova 37, 746 01 Opava (Czech Republic); Cudlin, Pavel [Institute of Systems Biology and Ecology of the AS CR, v.v.i., Na Sadkach 7, 37005 Ceske Budejovice (Czech Republic); Chroust, Petr [Ekotoxa s.r.o. - Centre for Environment and Land Assessment, Oticka 37, 746 01 Opava (Czech Republic); Urban, Otmar; Pokorny, Radek [Institute of Systems Biology and Ecology of the AS CR, v.v.i., Porici 3b, 60300 Brno (Czech Republic); Edwards-Jonasova, Magda [Institute of Systems Biology and Ecology of the AS CR, v.v.i., Na Sadkach 7, 37005 Ceske Budejovice (Czech Republic); Czerny, Radek; Janous, Dalibor; Taufarova, Klara [Institute of Systems Biology and Ecology of the AS CR, v.v.i., Porici 3b, 60300 Brno (Czech Republic); Vecera, Zbynek; Mikuska, Pavel [Institute of Analytical Chemistry of the AS CR, v.v.i., Veveri 97, 60200 Brno (Czech Republic); Paoletti, Elena [Institute of Plant Protection, National Research Council of Italy, via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)

    2011-05-15

    Daily ozone deposition flux to a Norway spruce forest in Czech Republic was measured using the gradient method in July and August 2008. Results were in good agreement with a deposition flux model. The mean daily stomatal uptake of ozone was around 47% of total deposition. Average deposition velocity was 0.39 cm s{sup -1} and 0.36 cm s{sup -1} by the gradient method and the deposition model, respectively. Measured and modelled non-stomatal uptake was around 0.2 cm s{sup -1}. In addition, net ecosystem production (NEP) was measured by using Eddy Covariance and correlations with O{sub 3} concentrations at 15 m a.g.l., total deposition and stomatal uptake were tested. Total deposition and stomatal uptake of ozone significantly decreased NEP, especially by high intensities of solar radiation. - Highlights: > We estimate ozone deposition flux to a Norway spruce forest using the gradient method and model. > The mean stomatal uptake of ozone is approximately 47% of the total deposition. > We measure net ecosystem production (NEP) using Eddy Covariance. > We test whether elevated total deposition and stomatal uptake of O{sub 3} imply a reduction of NEP. > Deposition and stomatal uptake of O{sub 3} decrease NEP, especially by high intensities of solar radiation. - Net ecosystem production of a Norway spruce forest decreases with increasing deposition and stomatal uptake of ozone.

  12. MetaFluxNet: the management of metabolic reaction information and quantitative metabolic flux analysis.

    Science.gov (United States)

    Lee, Dong-Yup; Yun, Hongsoek; Park, Sunwon; Lee, Sang Yup

    2003-11-01

    MetaFluxNet is a program package for managing information on the metabolic reaction network and for quantitatively analyzing metabolic fluxes in an interactive and customized way. It allows users to interpret and examine metabolic behavior in response to genetic and/or environmental modifications. As a result, quantitative in silico simulations of metabolic pathways can be carried out to understand the metabolic status and to design the metabolic engineering strategies. The main features of the program include a well-developed model construction environment, user-friendly interface for metabolic flux analysis (MFA), comparative MFA of strains having different genotypes under various environmental conditions, and automated pathway layout creation. http://mbel.kaist.ac.kr/ A manual for MetaFluxNet is available as PDF file.

  13. Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

    Science.gov (United States)

    Perez-Hoyos, Santiago; Sánchez-Lavega, A.

    2009-09-01

    We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  14. Surface Net Solar Radiation Estimated from Satellite Measurements: Comparisons with Tower Observations

    Science.gov (United States)

    Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

    1993-01-01

    A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation, which is presumably due to the predominance of different cloud types throughout the day. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged by using the temporally averaged column water vapor amount and the temporally averaged cosine of the solar zenith angle. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

  15. Production of fullerenes with concentrated solar flux

    Energy Technology Data Exchange (ETDEWEB)

    Hale, M. J.; Fields, C.; Lewandowski, A.; Bingham, C.; Pitts, R.

    1994-01-01

    Research at the National Renewable Energy Laboratory (NREL) has demonstrated that fullerenes can be produced using highly concentrated sunlight from a solar furnace. Since they were first synthesized in 1989, fullerenes have been the subject of intense research. They show considerable commercial potential in advanced materials and have potential applications that include semiconductors, superconductors, high-performance metals, and medical technologies. The most common fullerene is C{sub 60}, which is a molecule with a geometry resembling a soccer ball. Graphite vaporization methods such as pulsed-laser vaporization, resistive heating, and carbon arc have been used to produce fullerenes. None of these, however, seems capable of producing fullerenes economically on a large scale. The use of concentrated sunlight may help avoid the scale-up limitations inherent in more established production processes. Recently, researchers at NREL made fullerenes in NREL`s 10 kW High Flux Solar Furnace (HFSF) with a vacuum reaction chamber designed to deliver a solar flux of 1200 W/cm{sup 2} to a graphite pellet. Analysis of the resulting carbon soot by mass spectrometry and high-pressure liquid chromatography confirmed the existence of fullerenes. These results are very encouraging and we are optimistic that concentrated solar flux can provide a means for large-scale, economical production of fullerenes. This paper presents our method, experimental apparatus, and results of fullerene production research performed with the HFSF.

  16. Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model)

    Science.gov (United States)

    2017-09-01

    ARL-TR-8155 ● SEP 2017 US Army Research Laboratory Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model... Energy Research, Volume 5 (Solar Radiation Flux Model) by Clayton Walker and Gail Vaucher Computational and Information Sciences Directorate, ARL...2017 June 28 4. TITLE AND SUBTITLE Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model) 5a. CONTRACT NUMBER ROTC Internship

  17. Assessing surface solar radiation fluxes in CMIP5 model simulations

    Science.gov (United States)

    Loew, Alexander; Itkin, Mikhail; Andersson, Axel; Trentmann, Jörg; Fennig, Karsten; Schröder, Marc

    2014-05-01

    Sophisticated Earth System models (ESM) are an essential research tool for better understanding the global climate system and its interactions. They are indispensable tools for providing projections about potential evolutions of the Earth climate in the future. Given the complexity of these deterministic models, it is essential to have a solid knowledge of the uncertainties of the model results in difference aspects of the models. The present paper presents results from a comprehensive study analyzing the shortwave surface radiation fluxes. State-of-the-art globals datasets of surface radiation components (surface solar radiation flux, surface albedo, surface net radiation flux) are used to benchmark results from the recent Coupled Model Intercomparison Project (CMIP5) in a standardized manner at the regional to global scale. Different skill score metrices are compared. All CMIP5 models are ranked according to their performance skill scores. The uncertainties from current observational records compared to uncertainties in climate model simulations are also analyzed. The results indicate that there are still large uncertainties (inconsistencies) among the different existing global surface radiation dataset which lead to rather different (relative) model rankings. In other words, the rank of a model is not only determined by the skill of the model itself, but also largely by the choice of a benchmarking (reference) dataset. As the differences resulting from the choice of different observational datasets are larger than between different models, progress in surface radiation flux simulations of climate models might depend on further progress in achieving consistent observations of surface radiation fluxes from space.

  18. Flux Cancelation: The Key to Solar Eruptions

    Science.gov (United States)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald; Chakrapani, Prithi; Innes, Davina; Schmit, Don; Tiwari, Sanjiv

    2017-01-01

    Solar coronal jets are magnetically channeled eruptions that occur in all types of solar environments (e.g. active regions, quiet-Sun regions and coronal holes). Recent studies show that coronal jets are driven by the eruption of small-scare filaments (minifilaments). Once the eruption is underway magnetic reconnection evidently makes the jet spire and the bright emission in the jet base. However, the triggering mechanism of these eruptions and the formation mechanism of the pre-jet minifilaments are still open questions. In this talk, mainly using SDOAIA and SDOHIM data, first I will address the question: what triggers the jet-driving minifilament eruptions in different solar environments (coronal holes, quiet regions, active regions)? Then I will talk about the magnetic field evolution that produces the pre-jet minifilaments. By examining pre-jet evolutionary changes in line-of-sight HMI magnetograms while examining concurrent EUV images of coronal and transition-region emission, we find clear evidence that flux cancelation is the main process that builds pre-jet minifilaments, and is also the main process that triggers the eruptions. I will also present results from our ongoing work indicating that jet-driving minifilament eruptions are analogous to larger-scare filament eruptions that make flares and CMEs. We find that persistent flux cancellation at the neutral line of large-scale filaments often triggers their eruptions. From our observations we infer that flux cancelation is the fundamental process from the buildup and triggering of solar eruptions of all sizes.

  19. Zero-Net Mass-Flux Actuator Cavity Vortex

    Science.gov (United States)

    Krieg, Michael; Mohseni, Kamran

    2013-11-01

    Zero-Net Mass-Flux (ZNMT) devices are used commonly as synthetic jet actuators for flow control in various applications. The authors have recently proposed using larger ZNMF jet actuators for underwater propulsion; similar to squid and jellyfish. Generally the external flow generated by these devices is characterized according to momentum and energy transfer rates, and little attention is paid to the dynamics of flow inside the cavity. In fact the flow inside the cavity, especially during the refilling phase is not only highly dynamic but greatly influences the pressure distribution at the opening as well as the external flow during the following jetting phase. A completely transparent axisymmetric ZNMF cavity was constructed in order to investigate the internal vortex dynamics. The flow is seeded with reflective particles and illumined with a laser sheet bisecting the axis of symmetry. Standard 2D DPIV techniques are used to recover the velocity field in this cross section. During filling it is observed that a starting jet extending from the opening to the inside of the cavity rolls into a vortex ring much like the jetting phase. However, the effect of the cavity walls becomes apparent almost immediately. In this talk we characterize how the circulation within the cavity decays as a function of both cavity/orifice geometry and the mass flux program. In addition a load cell measures the total thrust acting on the device which is used to validate pressure calculations performed on the moving surface inside the cavity, showing excellent agreement. This work is supported by a grant from the Office of Naval Research.

  20. Properties of Flux Tubes and the Relation with Solar Irradiance ...

    Indian Academy of Sciences (India)

    At the solar surface the magnetic field is bundled into discrete elements of concentrated flux, often referred to as magnetic flux tubes, which cover only a small fraction of the solar surface. Flux tubes span a whole spectrum of sizes, ranging from sunspots to features well below the best currently obtainable spatial resolution.

  1. Mapping Daily Net CO2 Flux From Grasslands Using Remote Sensing

    Science.gov (United States)

    Holifield, C.; Emmerich, W.; Moran, M. S.; Bryant, R.; Verdugo, C.

    2003-12-01

    The daily net carbon dioxide (CO2) flux from extensive grassland ecosystems is an important component of the global carbon cycle. In previous studies, instantaneous net CO2 flux was estimated using a Water Deficit Index (WDI) determined from the relation between surface reflectance and temperature. The mean absolute difference between measured and WDI-derived CO2 flux was 0.23 over a range of CO2 flux values from -0.10 to 1.10 (mg m-2 s-1). The objective of this study was to determine daily net CO2 flux from instantaneous estimates for a semiarid grassland site in Southeast Arizona. This objective was reached through two main steps. First, a linear relationship (R2 = 0.95) was found between instantaneous net CO2 flux and net daytime (6 a.m. to 6 p.m.) flux and used to generate maps of daytime CO2 flux. Second, a field study was conducted to relate night time flux measurements to daytime measurements. These relations made it possible to map daily (24-hour) net CO2 flux from a single satellite image and basic meteorological information. A limitation of this approach is the dependence upon empirical relations for deriving daytime and night time estimates from instantaneous measurements. On the other hand, the empirical relations derived at this location were strong and consistent for the six-year study period.

  2. A Compact, Multi-view Net Flux Radiometer for Future Uranus and Neptune Probes

    Science.gov (United States)

    Aslam, S.; Amato, M.; Atkinson, D. H.; Hewagama, T.; Jennings, D. E.; Nixon, C. A.; Mousis, O.

    2017-01-01

    A Net Flux Radiometer (NFR) is presented that can be included in an atmospheric structure instrument suite for future probe missions to the icy giants Uranus and Neptune. The baseline design has two spectral channels i.e., a solar channel (0.4-to-3.5 m) and a thermal channel (4-to-300 m). The NFR is capable of viewing five distinct viewing angles during the descent. Non-imaging Winston cones with band-pass filters are used for each spectral channel and to define a 5 angular acceptance. Uncooled thermopile detectors are used in each spectral channel and are read out using a custom radiation hard application specific integrated circuit (ASIC). The baseline design can easily be changed to increase the number of detector channels from two to seven.

  3. Spatial-temporal variability in GHG fluxes and their functional interpretation in RusFluxNet

    Science.gov (United States)

    Vasenev, Ivan; Meshalkina, Julia; Sarzhanov, Dmitriy; Mazirov, Ilia; Yaroslavtsev, Alex; Komarova, Tatiana; Tikhonova, Maria

    2016-04-01

    High spatial and temporal variability is mutual feature for most modern boreal landscapes in the European Territory of Russia. This variability is result of their relatively young natural and land-use age with very complicated development stories. RusFluxNet includes a functionally-zonal set of representative natural, agricultural and urban ecosystems from the Central Forest Reserve in the north till the Central Chernozemic Reserve in the south (more than 1000 km distance). Especial attention has been traditionally given to their soil cover and land-use detailed variability, morphogenetic and functional dynamics. Central Forest Biosphere Reserve (360 km to North-West from Moscow) is the principal southern-taiga one in the European territory of Russia with long history of mature spruce ecosystem structure and dynamics investigation. Our studies (in frame of RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) have been concentrated on the soil carbon stocks and GHG fluxes spatial variability and dynamics due to dominated there windthrow and fallow-forest successions. In Moscow RTSAU campus gives a good possibility to develop the ecosystem and soil monitoring of GHG fluxes in the comparable sites of urban forest, field crops and lawn ecosystems taking especial attention on their meso- and micro-relief, soil cover patterns and subsoil, vegetation and land-use technologies, temperature and moisture spatial and temporal variability. In the Central Chernozemic Biosphere Reserve and adjacent areas we do the comparative analysis of GHG fluxes and balances in the virgin and mowed meadow-steppe, forest, pasture, cropland and three types of urban ecosystems with similar subsoil and relief conditions. The carried out researches have shown not only sharp (in 2-5 times) changes in GHG ecosystem and soil fluxes and balances due to seasonal and daily microclimate variation, vegetation and crop development but their essential (in 2-4 times) spatial variability due to

  4. NACP North American 8-km Net Ecosystem Exchange and Component Fluxes, 2004

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides modeled carbon flux estimates at 8-km spatial resolution over North America for the year 2004 of (1) net ecosystem exchange (NEE) of carbon...

  5. Development of a Net Flux Radiometer for the Hera Saturn Probe Mission

    Science.gov (United States)

    Aslam, Shahid; Amato, Michael; Atkinson, David; Mousis, Olivier; Nixon, Conor; Simon, Amy A.; Hera Probe Mission Team

    2016-10-01

    In situ exploration of all the giant planets in the outer solar system is an imperative and a Saturn probe is the next compelling step beyond Galileo's in situ exploration of Jupiter, the remote investigation of its interior, gravity, and magnetic fields by the Juno mission, and the Cassini spacecraft's similar orbital reconnaissance of Saturn. One such proposed future mission is "HERA: an international atmospheric probe to unveil the depths of Saturn" a nominal configuration is a combined ESA/Class-M probe mission accompanied by a launch vehicle and carrier relay spacecraft provided by NASA. One of the instruments being considered for inclusion on the probe is a Net Flux Radiometer (NFR) to unravel the vertical structure and properties of Saturn's cloud and haze layers. A NFR concept is presented that can be included in an atmospheric structure instrument suite for the Hera mission. The current design has two spectral channels i.e., a solar channel (0.4-to-5 µm) and a thermal channel (4-to-50 µm). The NFR is capable of viewing five distinct viewing angles during the descent. Non-imaging Winston cones with window and filter combinations define the spectral channels with a 5° Field-Of View (FOV). Uncooled thermopile detectors are used in each spectral channel and are read out using a custom designed radiation-hard Application Specific Integrated Circuit (ASIC).

  6. Time Exceedances for High Intensity Solar Proton Fluxes

    Science.gov (United States)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adam, James H., Jr.; Dietrich, William F.

    2011-01-01

    A model is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  7. A Study of the Solar Proton Flux Model

    Science.gov (United States)

    Li, Ting-Ting; Shi, Li-Qin; Liu, Si-Qing

    2011-01-01

    The solar proton event (SPE) may become a serious threat to the cosmonautical activities of human beings, so the prediction of the flux of solar protons within a certain period has important guiding significance for the projection of the anti-radiation solidification of space vehicles. On the basis of a statistical analysis of the data of SPEs in the 20th to 23rd cycles of solar activity, a new model of solar proton fluxes with E > 10 MeV and E > 30 MeV is established. In comparison with the JPL model, which is frequently adopted in the present aerospace engineering, the influence factor of solar activity on the occurrence of proton events is introduced, and it can be used to estimate the proton fluxes under various levels of solar activity. The results can better match the characteristics of the distribution of proton events.

  8. Tracking heat flux sensors for concentrating solar applications

    Science.gov (United States)

    Andraka, Charles E; Diver, Jr., Richard B

    2013-06-11

    Innovative tracking heat flux sensors located at or near the solar collector's focus for centering the concentrated image on a receiver assembly. With flux sensors mounted near a receiver's aperture, the flux gradient near the focus of a dish or trough collector can be used to precisely position the focused solar flux on the receiver. The heat flux sensors comprise two closely-coupled thermocouple junctions with opposing electrical polarity that are separated by a thermal resistor. This arrangement creates an electrical signal proportional to heat flux intensity, and largely independent of temperature. The sensors are thermally grounded to allow a temperature difference to develop across the thermal resistor, and are cooled by a heat sink to maintain an acceptable operating temperature.

  9. Flux ropes in the magnetic solar convection zone

    DEFF Research Database (Denmark)

    Dorch, S. B. F.

    2006-01-01

    In this contribution results are presented on how twisted magnetic flux ropes interact with a magnetized model envelope similar to the solar convection zone. Both the flux ropes and the atmosphere are modelled as idealized 2.5-dimensional concepts using high resolution numerical MHD simulations (on...

  10. Net carbon flux from agricultural ecosystems: methodology for full carbon cycle analyses.

    Science.gov (United States)

    West, T O; Marland, G

    2002-01-01

    Agricultural ecosystems have the potential to sequester carbon in soils by altering agricultural management practices (i.e. tillage practice, cover crops, and crop rotation) and using agricultural inputs (i.e. fertilizers and irrigation) more efficiently. Changes in agricultural practices can also cause changes in CO2 emissions associated with these practices. In order to account for changes in net CO2 emissions, and thereby estimate the overall impact of carbon sequestration initiatives on the atmospheric CO2 pool, we use a methodology for full carbon cycle analysis of agricultural ecosystems. The analysis accounts for changes in carbon sequestration and emission rates with time, and results in values representing a change in net carbon flux. Comparison among values of net carbon flux for two or more systems, using the initial system as a baseline value, results in a value for relative net carbon flux. Some results from using the full carbon cycle methodology, along with US national average values for agricultural inputs, indicate that the net carbon flux averaged over all crops following conversion from conventional tillage to no-till is -189 kg C ha(-1) year(-1) (a negative value indicates net transfer of carbon from the atmosphere). The relative net carbon flux, using conventional tillage as the baseline, is -371 kg C ha(-1) year(-1), which represents the total atmospheric CO2 reduction caused by changing tillage practices. The methodology used here illustrates the importance of (1) delineating system boundaries, (2) including CO2 emissions associated with sequestration initiatives in the accounting process, and (3) comparing the new management practices associated with sequestration initiatives with the original management practices to obtain the true impact of sequestration projects on the atmospheric CO2 pool.

  11. Evaluation of satellite and reanalysis-based global net surface energy flux and uncertainty estimates

    Science.gov (United States)

    Allan, Richard; Liu, Chunlei

    2017-04-01

    The net surface energy flux is central to the climate system yet observational limitations lead to substantial uncertainty (Trenberth and Fasullo, 2013; Roberts et al., 2016). A combination of satellite-derived radiative fluxes at the top of atmosphere (TOA) adjusted using the latest estimation of the net heat uptake of the Earth system, and the atmospheric energy tendencies and transports from the ERA-Interim reanalysis are used to estimate surface energy flux globally (Liu et al., 2015). Land surface fluxes are adjusted through a simple energy balance approach using relations at each grid point with the consideration of snowmelt to improve regional realism. The energy adjustment is redistributed over the oceans using a weighting function to avoid meridional discontinuities. Uncertainties in surface fluxes are investigated using a variety of approaches including comparison with a range of atmospheric reanalysis input data and products. Zonal multiannual mean surface flux uncertainty is estimated to be less than 5 Wm-2 but much larger uncertainty is likely for regional monthly values. The meridional energy transport is calculated using the net surface heat fluxes estimated in this study and the result shows better agreement with observations in Atlantic than before. The derived turbulent fluxes (difference between the net heat flux and the CERES EBAF radiative flux at surface) also have good agreement with those from OAFLUX dataset and buoy observations. Decadal changes in the global energy budget and the hemisphere energy imbalances are quantified and present day cross-equator heat transports is re-evaluated as 0.22±0.15 PW southward by the atmosphere and 0.32±0.16 PW northward by the ocean considering the observed ocean heat sinks (Roemmich et al., 2006) . Liu et al. (2015) Combining satellite observations and reanalysis energy transports to estimate global net surface energy fluxes 1985-2012. J. Geophys. Res., Atmospheres. ISSN 2169-8996 doi: 10.1002/2015JD

  12. Net Ecosystem Fluxes of Hydrocarbons from a Ponderosa Pine Forest in Colorado

    Science.gov (United States)

    Rhew, R. C.; Turnipseed, A. A.; Ortega, J. V.; Smith, J. N.; Guenther, A. B.; Shen, S.; Martinez, L.; Koss, A.; Warneke, C.; De Gouw, J. A.; Deventer, M. J.

    2015-12-01

    Light (C2-C4) alkenes, light alkanes and isoprene (C5H8) are non-methane hydrocarbons that play important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. Natural terrestrial fluxes of the light hydrocarbons are poorly characterized, with global emission estimates based on limited field measurements. In 2014, net fluxes of these compounds were measured at the Manitou Experimental Forest Observatory, a semi-arid ponderosa pine forest in the Colorado Rocky Mountains and site of the prior BEACHON campaigns. Three field intensives were conducted between June 17 and August 10, 2014. Net ecosystem flux measurements utilized a relaxed eddy accumulation system coupled to an automated gas chromatograph. Summertime average emissions of ethene and propene were up to 90% larger than those observed from a temperate deciduous forest. Ethene and propene fluxes were also correlated to each other, similar to the deciduous forest study. Emissions of isoprene were small, as expected for a coniferous forest, and these fluxes were not correlated with either ethene or propene. Unexpected emissions of light alkanes were also observed, and these showed a distinct diurnal cycle. Understory flux measurements allowed for the partitioning of fluxes between the surface and the canopy. Full results from the three field intensives will be compared with environmental variables in order to parameterize the fluxes for use in modeling emissions.

  13. Channelling can affect concentrations of metabolic intermediates at constant net flux: artefact or reality?

    Science.gov (United States)

    Cornish-Bowden, A; Cárdenas, M L

    1993-04-01

    We show that if a metabolic intermediate is directly transferred ('channelled') from an enzyme that catalyses its production to another that uses it as substrate, there is no change in its free concentration compared with a system with the same net flux in which there is no direct transfer. Thus the widespread idea that channelling provides a mechanism for decreasing metabolite concentrations at constant flux is false. Results from computer simulation that suggest otherwise [Mendes, P., Kell, D. B. & Westerhoff, H. V. (1992) Eur. J. Biochem. 204, 257-266] are artefacts either of variations in flux or of alterations in opposite directions of the activities of the relevant enzymes.

  14. Validation of a minimum microclimate disturbance chamber for net ecosystem flux measurements

    NARCIS (Netherlands)

    Graf, A.; Werner, J.; Langensiepen, M.; Boer, van de A.; Schmidt, M.; Kupisch, M.; Vereecken, H.

    2013-01-01

    A minimum-disturbance chamber for canopy net CO2 and H2O flux measurements is described. The system is a passively (optionally actively) ventilated tunnel with large (similar to 0.14 m2) in- and outlet cross sections covering a surface area of approximately 1.6 m2. A differential, non-drying

  15. Solar neutrino flux at keV energies

    Science.gov (United States)

    Vitagliano, Edoardo; Redondo, Javier; Raffelt, Georg

    2017-12-01

    We calculate the solar neutrino and antineutrino flux in the keV energy range. The dominant thermal source processes are photo production (γ e→ e νbar nu), bremsstrahlung (e+Ze→ Ze+e+νbar nu), plasmon decay (γ→νbar nu), and νbar nu emission in free-bound and bound-bound transitions of partially ionized elements heavier than hydrogen and helium. These latter processes dominate in the energy range of a few keV and thus carry information about the solar metallicity. To calculate their rate we use libraries of monochromatic photon radiative opacities in analogy to a previous calculation of solar axion emission. Our overall flux spectrum and many details differ significantly from previous works. While this low-energy flux is not measurable with present-day technology, it could become a significant background for future direct searches for keV-mass sterile neutrino dark matter.

  16. Net Ecosystem Fluxes of Methyl Halides from a Coastal Salt Marsh with Invasive Pepperweed

    Science.gov (United States)

    Deventer, M. J.; Jiao, Y.; Lewis, J. A.; Weiss, R. F.; Rhew, R. C.; Turnipseed, A. A.

    2016-12-01

    Terrestrial emissions of methyl bromide (CH3Br) and methyl chloride (CH3Cl) are believed to constitute the `missing' source of these compounds to the atmosphere, but the variability of emission rates from natural ecosystems has led to large uncertainties in scaling up. Since April 2016, surface-atmosphere fluxes for methyl halides have been measured at Suisun Marsh, a coastal salt marsh in northern California, USA. Flux measurements are performed in two ways: tower based relaxed eddy accumulation (REA) for net ecosystem fluxes and static flux chamber measurements for plant-scale fluxes. The study site is invaded by perennial pepperweed (Lepidium latifolium), a methyl halide emitting species, covering a significant part of the flux source area. Both, REA and chamber samples are analyzed for methyl chloride (CH3Cl) and methyl bromide (CH3Br) using gas chromatography with electron capture detector (GC-ECD). The analytical precision [ppt] and REA flux detection limits [μmol m-2 d-1] are on the order of 3.9/0.6 for CH3Cl and 0.01/0.2 for CH3Br. Chamber measurements confirmed that methyl halide emissions of pepperweed are large, but that the native alkali heath (Frankenia salina) is a much stronger emitter, when normalized by biomass. REA measurements show that during the summer, the studied marsh is a substantial methyl halide source with net fluxes of 20 μmol m-2 d-1 (CH3Cl) and 1 μmol m-2 d-1 (CH3Br). Notably, these fluxes are comparable with reported chamber based emissions from southern California salt marshes. Furthermore, a positive response to light and temperature was found. The presentation will also expand on the diurnal variability and seasonality of the measured fluxes.

  17. Flux concentrations on solar dynamic components due to mispointing

    Science.gov (United States)

    Rylicki, Daniel S.

    1992-01-01

    Mispointing of the solar dynamic (SD) concentrator designed for use on Space Station Freedom (SSF) causes the optical axis of the concentrator to be nonparallel to the incoming rays from the Sun. This causes solar flux not to be focused into the aperture hole of the receiver and may position the flux on other SSF components. A Rocketdyne analysis has determined the thermal impact of off-axis radiation due to mispointing on elements of the SD module and photovoltaic (PV) arrays. The conclusion was that flux distributions on some of the radiator components, the two-axis gimbal rings, the truss, and the PV arrays could present problems. The OFFSET computer code was used at Lewis Research Center to further investigate these flux distributions incident on components. The Lewis study included distributions for a greater range of mispoint angles than the Rocketdyne study.

  18. Equilibrium model of thin magnetic flux tubes. [solar atmosphere

    Science.gov (United States)

    Bodo, G.; Ferrari, A.; Massaglia, S.; Kalkofen, W.; Rosner, R.

    1984-01-01

    The existence of a physically realizable domain in which approximations that lead to a self consistent solution for flux tube stratification in the solar atmosphere, without ad hoc hypotheses, is proved. The transfer equation is solved assuming that no energy transport other than radiative is present. Convective motions inside the tube are assumed to be suppressed by magnetic forces. Only one parameter, the plasma beta at tau = 0, must be specified, and this can be estimated from observations of spatially resolved flux tubes.

  19. Caprolactam production by direct solar flux

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, J.; Wong, E.H.S.; Mathur, V.K. (Univ. of New Hampshire, Durham (United States))

    1991-01-01

    The use of solar energy for the photonitrozation of cyclohexane for the production of cyclohexanone oxime hydrochloride, an intermediate for the manufacture of caprolactam, is discussed. Experimental results show the technical feasibility of such a reaction in the presence of radiation of wavelength 350-550 nm simulating sunlight.

  20. Solar and Net Radiation for Estimating Potential Evaporation from Three Vegetation Canopies

    Science.gov (United States)

    D.M. Amatya; R.W. Skaggs; G.W. Cheschier; G.P. Fernandez

    2000-01-01

    Solar and net radiation data are frequent/y used in estimating potential evaporation (PE) from various vegetative surfaces needed for water balance and hydrologic modeling studies. Weather parameters such as air temperature, relative humidity, wind speed, solar radiation, and net radiation have been continuously monitored using automated sensors to estimate PE for...

  1. Galileo probe measurements of thermal and solar radiation fluxes in the Jovian atmosphere

    Science.gov (United States)

    Sromovsky, L. A.; Collard, A. D.; Fry, P. M.; Orton, G. S.; Lemmon, M. T.; Tomasko, M. G.; Freedman, R. S.

    1998-09-01

    The Galileo probe net flux radiometer (NFR) measured radiation fluxes in Jupiter's atmosphere from about 0.44 to 14 bars, using five spectral channels to separate solar and thermal components. Onboard calibration results confirm that the NFR responded to radiation approximately as expected. NFR channels also responded to a superimposed thermal perturbation, which can be approximately removed using blind channel measurements and physical constraints. Evidence for the expected NH3 cloud was seen in the spectral character of spin-induced modulations of the direct solar beam signals. These results are consistent with an overlying cloud of small NH3 ice particles (0.5-0.75 μm in radius) of optical depth 1.5-2 at 0.5 μm. Such a cloud would have so little effect on thermal fluxes that NFR thermal channels provide no additional constraints on its properties. However, evidence for heating near 0.45 bar in the NFR thermal channels would seem to require either an additional opacity source beyond this small-particle cloud, implying a heterogeneous cloud structure to avoid conflicts with solar modulation results, or a change in temperature lapse rate just above the probe measurements. The large thermal flux levels imply water vapor mixing ratios that are only 6% of solar at 10 bars, but possibly increasing with depth, and significantly subsaturated ammonia at pressures less than 3 bars. If deep NH3 mixing ratios at the probe entry site are 3-4 times ground-based inferences, as suggested by probe radio signal attenuation, then only half as much water is needed to match NFR observations. No evidence of a water cloud was seen near the 5-bar level. The 5-μm thermal channel detected the presumed NH4SH cloud base near 1.35 bars. Effects of this cloud were also seen in the solar channel upflux measurements but not in the solar net fluxes, implying that the cloud is a conservative scatterer of sunlight. The minor thermal signature of this cloud is compatible with particle radii near

  2. Predicting Solar Cycle 25 using Surface Flux Transport Model

    Science.gov (United States)

    Imada, Shinsuke; Iijima, Haruhisa; Hotta, Hideyuki; Shiota, Daiko; Kusano, Kanya

    2017-08-01

    It is thought that the longer-term variations of the solar activity may affect the Earth’s climate. Therefore, predicting the next solar cycle is crucial for the forecast of the “solar-terrestrial environment”. To build prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar activity is intensively discussed. Because we can determine the polar magnetic field at the solar minimum roughly 3 years before the next solar maximum, we may discuss the next solar cycle 3years before. Further, the longer term (~5 years) prediction might be achieved by estimating the polar magnetic field with the Surface Flux Transport (SFT) model. Now, we are developing a prediction scheme by SFT model as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction) and adapting to the Cycle 25 prediction. The predicted polar field strength of Cycle 24/25 minimum is several tens of percent smaller than Cycle 23/24 minimum. The result suggests that the amplitude of Cycle 25 is weaker than the current cycle. We also try to obtain the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters will be used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle and discuss the initial results for Cycle 25 prediction.

  3. Temporal and spatial changes in mixed layer properties and atmospheric net heat flux in the Nordic Seas

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A; Alekseev, G [SI ' Arctic and Antarctic Research Institute' , St. Petersburg (Russian Federation); Korablev, A; Esau, I, E-mail: avsmir@aari.nw.r [Nansen Environmental and Remote Sensing Centre, Bergen (Norway)

    2010-08-15

    The Nordic Seas are an important area of the World Ocean where warm Atlantic waters penetrate far north forming the mild climate of Northern Europe. These waters represent the northern rim of the global thermohaline circulation. Estimates of the relationships between the net heat flux and mixed layer properties in the Nordic Seas are examined. Oceanographic data are derived from the Oceanographic Data Base (ODB) compiled in the Arctic and Antarctic Research Institute. Ocean weather ship 'Mike' (OWS) data are used to calculate radiative and turbulent components of the net heat flux. The net shortwave flux was calculated using a satellite albedo dataset and the EPA model. The net longwave flux was estimated by Southampton Oceanography Centre (SOC) method. Turbulent fluxes at the air-sea interface were calculated using the COARE 3.0 algorithm. The net heat flux was calculated by using oceanographic and meteorological data of the OWS 'Mike'. The mixed layer depth was estimated for the period since 2002 until 2009 by the 'Mike' data as well. A good correlation between these two parameters has been found. Sensible and latent heat fluxes controlled by surface air temperature/sea surface temperature gradient are the main contributors into net heat flux. Significant correlation was found between heat fluxes variations at the OWS 'Mike' location and sea ice export from the Arctic Ocean.

  4. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    Science.gov (United States)

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P < 0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P < 0.001). Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise. © 2015 John Wiley & Sons Ltd.

  5. Updated determination of the solar neutrino fluxes from solar neutrino data

    Energy Technology Data Exchange (ETDEWEB)

    Bergström, Johannes [Departament d’Estructura i Constituents de la Matèria and Institut de Ciencies del Cosmos,Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Gonzalez-Garcia, M. C. [Departament d’Estructura i Constituents de la Matèria and Institut de Ciencies del Cosmos,Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA) (Spain); C.N. Yang Institute for Theoretical Physics,State University of New York at Stony Brook, Stony Brook, NY 11794-3840 (United States); Maltoni, Michele [Instituto de Física Teórica UAM/CSIC,Calle de Nicolás Cabrera 13-15, Universidad Autónoma de Madrid,Cantoblanco, E-28049 Madrid (Spain); Peña-Garay, Carlos [Instituto de Física Corpuscular (IFIC), CSIC and Universitat de Valencia,Calle Catedrático José Beltrán, 2, E-46090 Paterna, Valencia (Spain); Serenelli, Aldo M. [Institut de Ciencies de l’Espai (ICE-CSIC/IEEC),Campus UAB, Carrer de Can Magrans s/n, 08193 Cerdanyola del Valls (Spain); Song, Ningqiang [C.N. Yang Institute for Theoretical Physics,State University of New York at Stony Brook, Stony Brook, NY 11794-3840 (United States)

    2016-03-18

    We present an update of the determination of the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. We then use these results to compare the description provided by different Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with equivalent statistical agreement. We also argue that even with the present experimental precision the solar neutrino data have the potential to improve the accuracy of the solar model predictions.

  6. SURFACE ALFVEN WAVES IN SOLAR FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Andries, J.; Soler, R.; Van Doorsselaere, T. [Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Arregui, I.; Terradas, J., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2012-07-10

    Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. Alfven waves and magneto-sonic waves are particular classes of MHD waves. These wave modes are clearly different and have pure properties in uniform plasmas of infinite extent only. Due to plasma non-uniformity, MHD waves have mixed properties and cannot be classified as pure Alfven or magneto-sonic waves. However, vorticity is a quantity unequivocally related to Alfven waves as compression is for magneto-sonic waves. Here, we investigate MHD waves superimposed on a one-dimensional non-uniform straight cylinder with constant magnetic field. For a piecewise constant density profile, we find that the fundamental radial modes of the non-axisymmetric waves have the same properties as surface Alfven waves at a true discontinuity in density. Contrary to the classic Alfven waves in a uniform plasma of infinite extent, vorticity is zero everywhere except at the cylinder boundary. If the discontinuity in density is replaced with a continuous variation of density, vorticity is spread out over the whole interval with non-uniform density. The fundamental radial modes of the non-axisymmetric waves do not need compression to exist unlike the radial overtones. In thin magnetic cylinders, the fundamental radial modes of the non-axisymmetric waves with phase velocities between the internal and the external Alfven velocities can be considered as surface Alfven waves. On the contrary, the radial overtones can be related to fast-like magneto-sonic modes.

  7. Solar axion flux from the axion-electron coupling

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier, E-mail: redondo@mpp.mpg.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstr. 37, D-80333 München (Germany)

    2013-12-01

    In non-hadronic axion models, where axions couple to electrons at tree level, the solar axion flux is completely dominated by the ABC reactions (Atomic recombination and deexcitation, Bremsstrahlung and Compton). In this paper the ABC flux is computed from available libraries of monochromatic photon radiative opacities (OP, LEDCOP and OPAS) by exploiting the relations between axion and photon emission cross sections. These results turn to be ∼ 30% larger than previous estimates due to atomic recombination (free-bound electron transitions) and deexcitation (bound-bound), which where not previously taken into account.

  8. Effect of site of starch digestion on portal nutrient net fluxes in steers.

    Science.gov (United States)

    Nozière, Pierre; Rémond, Didier; Lemosquet, Sophie; Chauveau, Béatrice; Durand, Denys; Poncet, Claude

    2005-08-01

    Processing of maize grain is known to modulate the site of starch digestion, thus the nature and amount of nutrients delivered for absorption. We assessed the effect of site of starch digestion on nutrient net fluxes across portal-drained viscera (PDV). Three steers, fitted with permanent digestive cannulas and blood catheters, successively received two diets containing 35 % starch as dent maize grain. Diets differed according to maize presentation: dry and cracked (by-pass, BP) v. wet and ground (control, C). Ruminal physicochemical parameters were not significantly affected. Between C and BP, the decrease in ruminal starch digestion was compensated by an increase in starch digestion in the small intestine. The amount of glucose and soluble alpha-glucoside reaching the ileum was not affected. The amount of glucose disappearing in the small intestine increased from 238 to 531 g/d between C and BP, but portal net flux of glucose remained unchanged (-97 g/d). The portal O2 consumption and net energy release were not significantly affected, averaging 16 % and 57 % of metabolizable energy intake, respectively. The whole-body glucose appearance rate, measured by jugular infusion of [6,6-2H2]glucose, averaged 916 g/d. The present study shows that the increase in the amount of glucose disappearing in the small intestine of conventionally fed cattle at a moderate intake level induces no change in portal net flux of glucose, reflecting an increase in glucose utilization by PDV. That could contribute to the low response of whole-body glucose appearance rate observed at this moderate level of intestinal glucose supply.

  9. High-flux solar photon processes: Opportunities for applications

    Energy Technology Data Exchange (ETDEWEB)

    Steinfeld, J.I.; Coy, S.L.; Herzog, H.; Shorter, J.A.; Schlamp, M.; Tester, J.W.; Peters, W.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1992-06-01

    The overall goal of this study was to identify new high-flux solar photon (HFSP) processes that show promise of being feasible and in the national interest. Electric power generation and hazardous waste destruction were excluded from this study at sponsor request. Our overall conclusion is that there is promise for new applications of concentrated solar photons, especially in certain aspects of materials processing and premium materials synthesis. Evaluation of the full potential of these and other possible applications, including opportunities for commercialization, requires further research and testing. 100 refs.

  10. Helical Motion of Magnetic Flux Tubes in the Solar Atmosphere

    Science.gov (United States)

    Zaqarashvili, T. V.; Skhirtladze, N.

    2008-08-01

    Photospheric granulation may excite transverse kink pulses in anchored vertical magnetic flux tubes. The pulses propagate upward along the tubes with the kink speed, while oscillating wakes are formed behind the wave front in a stratified atmosphere. The wakes oscillate at the kink cutoff frequency of stratified medium and gradually decay in time. When two or more consecutive kink pulses with different polarizations propagate in the same thin tube, then the wakes corresponding to different pulses may be superimposed. The superposition sets up helical motions of magnetic flux tubes in the photosphere/chromosphere as seen in recent Hinode movies. The energy carried by the pulses is enough to heat the solar chromosphere/corona and accelerate the solar wind.

  11. Fluting Modes in Transversely Nonuniform Solar Flux Tubes

    Science.gov (United States)

    Soler, Roberto

    2017-12-01

    Magnetohydrodynamic waves of different types are frequently observed in magnetic flux tubes of the solar atmosphere and are often modeled using simple models. In the standard flux tube model made of a straight uniform tube with an abrupt boundary, transverse wave modes are classified according to their azimuthal wavenumber, m. Sausage (m = 0) and kink (m = 1) modes produce pulsations of the cross section and transverse oscillations of tube axis, respectively. Both sausage and kink modes have been observed in the solar atmosphere. Fluting (m≥slant 2) modes produce perturbations that are essentially confined around the boundary of the tube, I.e., they have a strong surface-like character. Unlike sausage and kink modes, the detection of fluting modes remains elusive. Here we show that the inclusion of transverse inhomogeneity in the flux tube model dramatically affects the properties of fluting modes. Even in a thin tube, kink and fluting modes are no longer degenerate in frequency when the tube has a smooth boundary. In addition, fluting modes become heavily damped by resonant absorption in a timescale shorter than the oscillation period. The perturbations loose their global shape and their distinctive surface-like appearance. As a consequence of that, we argue that nonuniform flux tubes with smooth boundaries may not be able to support fluting-like perturbations as coherent, global modes.

  12. Flow instabilities of magnetic flux tubes. IV. Flux storage in the solar overshoot region

    Science.gov (United States)

    Işık, E.; Holzwarth, V.

    2009-12-01

    Context: Flow-induced instabilities of magnetic flux tubes are relevant to the storage of magnetic flux in the interiors of stars with outer convection zones. The stability of magnetic fields in stellar interiors is of importance to the generation and transport of solar and stellar magnetic fields. Aims: We consider the effects of material flows on the dynamics of toroidal magnetic flux tubes located close to the base of the solar convection zone, initially within the overshoot region. The problem is to find the physical conditions in which magnetic flux can be stored for periods comparable to the dynamo amplification time, which is of the order of a few years. Methods: We carry out nonlinear numerical simulations to investigate the stability and dynamics of thin flux tubes subject to perpendicular and longitudinal flows. We compare the simulations with the results of simplified analytical approximations. Results: The longitudinal flow instability induced by the aerodynamic drag force is nonlinear in the sense that the growth rate depends on the perturbation amplitude. This result is consistent with the predictions of linear theory. Numerical simulations without friction show that nonlinear Parker instability can be triggered below the linear threshold of the field strength, when the difference in superadiabaticity along the tube is sufficiently large. A localised downflow acting on a toroidal tube in the overshoot region leads to instability depending on the parameters describing the flow, as well as the magnetic field strength. We determined ranges of the flow parameters for which a linearly Parker-stable magnetic flux tube is stored in the middle of the overshoot region for a period comparable to the dynamo amplification time. Conclusions: The longitudinal flow instability driven by frictional interaction of a flux tube with its surroundings is relevant to determining the storage time of magnetic flux in the solar overshoot region. The residence time for

  13. Sustained Magnetorotational Turbulence in Local Simulations of Stratified Disks with Zero Net Magnetic Flux

    DEFF Research Database (Denmark)

    W. Davis, S.; M. Stone, J.; Pessah, Martin Elias

    2010-01-01

    We examine the effects of density stratification on magnetohydrodynamic turbulence driven by the magnetorotational instability in local simulations that adopt the shearing box approximation. Our primary result is that, even in the absence of explicit dissipation, the addition of vertical gravity...... leads to convergence in the turbulent energy densities and stresses as the resolution increases, contrary to results for zero net flux, unstratified boxes. The ratio of total stress to midplane pressure has a mean of ~0.01, although there can be significant fluctuations on long (>~50 orbit) timescales...

  14. [Net CO2 exchange and carbon isotope flux in Acacia mangium plantation].

    Science.gov (United States)

    Zou, Lu-Liu; Sun, Gu-Chou; Zhao, Ping; Cai, Xi-An; Zeng, Xiao-Ping; Wang, Quan

    2009-11-01

    By using stable carbon isotope technique, the leaf-level 13C discrimination was integrated to canopy-scale photosynthetic discrimination (Deltacanopy) through weighted the net CO2 assimilation (Anet) of sunlit and shaded leaves and the stand leaf area index (L) in an A. mangium plantation, and the carbon isotope fluxes from photosynthesis and respiration as well as their net exchange flux were obtained. There was an obvious diurnal variation in Deltacanopy, being lower at dawn and at noon time (18.47 per thousand and 19.87 per thousand, respectively) and the highest (21.21 per thousand) at dusk. From the end of November to next May, the Deltacanopy had an increasing trend, with an annual average of (20.37 +/- 0.29) per thousand. The carbon isotope ratios of CO2 from autotrophic respiration (excluding daytime foliar respiration) and heterotrophic respiration were respectively (- 28.70 +/- 0.75) per thousand and (- 26.75 +/- 1.3) per thousand in average. The delta13 C of nighttime ecosystem-respired CO2 in May was the lowest (-30.14 per thousand), while that in November was the highest (-28.01 per thousand). The carbon isotope flux of CO2 between A. mangium forest and atmosphere showed a midday peak of 178.5 and 217 micromol x m(-2) x s(-1) x per thousand in May and July, with the daily average of 638.4 and 873.2 micromol x m(-2) x s(-1) x per thousand, respectively. The carbon isotope flux of CO2 absorbed by canopy leaves was 1.6-2.5 times higher than that of CO2 emitted from respiration, suggesting that a large sum of CO2 was absorbed by A. mangium, which decreased the atmospheric CO2 concentration and improved the environment.

  15. Origin and Structures of Solar Eruptions I: Magnetic Flux Rope

    Science.gov (United States)

    Cheng, Xin; Guo, Yang; Ding, MingDe

    2017-08-01

    Coronal mass ejections (CMEs) and solar flares are the large-scale and most energetic eruptive phenomena in our solar system and able to release a large quantity of plasma and magnetic flux from the solar atmosphere into the solar wind. When these high-speed magnetized plasmas along with the energetic particles arrive at the Earth, they may interact with the magnetosphere and ionosphere, and seriously affect the safety of human high-tech activities in outer space. The travel time of a CME to 1 AU is about 1-3 days, while energetic particles from the eruptions arrive even earlier. An efficient forecast of these phenomena therefore requires a clear detection of CMEs/flares at the stage as early as possible. To estimate the possibility of an eruption leading to a CME/flare, we need to elucidate some fundamental but elusive processes including in particular the origin and structures of CMEs/flares. Understanding these processes can not only improve the prediction of the occurrence of CMEs/flares and their effects on geospace and the heliosphere but also help understand the mass ejections and flares on other solar-type stars. The main purpose of this review is to address the origin and early structures of CMEs/flares, from multi-wavelength observational perspective. First of all, we start with the ongoing debate of whether the pre-eruptive configuration, i.e., a helical magnetic flux rope (MFR), of CMEs/flares exists before the eruption and then emphatically introduce observational manifestations of the MFR. Secondly, we elaborate on the possible formation mechanisms of the MFR through distinct ways. Thirdly, we discuss the initiation of the MFR and associated dynamics during its evolution toward the CME/flare. Finally, we come to some conclusions and put forward some prospects in the future.

  16. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    Science.gov (United States)

    Lockwood, Mike; Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.Plain Language SummaryThere is growing interest in being able to predict the evolution in solar conditions on a better basis than past experience, which is necessarily limited. Two of the key features of the solar magnetic cycle are that the polar fields reverse just after the peak of each sunspot cycle and that the polar field that has accumulated by the time of each sunspot minimum is a good indicator of the amplitude

  17. Asteroidal and cometary dust flux in the inner solar system

    Science.gov (United States)

    Borin, P.; Cremonese, G.; Marzari, F.; Lucchetti, A.

    2017-09-01

    Context. Meteoroids impacting terrestrial planets at high speed may have different effects. On bodies without atmospheres, such as the Moon and Mercury, they form impact craters and contribute to the gardening process through which the surface material is constantly mixed. The interaction of high-speed meteoroids with the atmosphere of Venus, the Earth, and Mars, may lead to the deposition in the ionosphere of species such as neutral Mg or Fe and their ionized atoms, caused by ablation processes during the entry. Aims: In this work we estimate and compare the flux and impact speeds onto the planets of the inner solar system by numerically integrating the orbital evolution of putative dust particles of asteroidal and cometary origin. Methods: The trajectories of dust particles of different sizes are computed with a numerical code that accounts for the gravitational forces due to all planets, the Poynting-Robertson drag and the solar wind drag. The flux of dust grains on each planet is estimated by calibrating the outcome of our model with the flux on the Earth reported previously. Results: We obtain new estimates of the flux and impact velocities for both asteroidal and cometary dust particles on Venus and Mars. For Venus we find that cometary grains enter the planet atmosphere at higher speeds, possibly contributing to the upper layers, while asteroidal grains would be relevant for the lower layers, possibly leading to a compositional gradient. This effect is also present for Mars, but it is less marked. We also find that analytical predictions, not taking radiative forces into account, of both flux and average impact speed are reliable for Mars but fail for Venus because of the complex dynamical evolution of grains in the inner solar system. Conclusions: Our results on the velocity distributions and fluxes of micrometeoroids on the terrestrial planets can be used to put stringent contraints on models that estimate either the superficial material mixing that is due

  18. Land Use Effects on Net Greenhouse Gas Fluxes in the US Great Plains: Historical Trends and Model Projections

    Science.gov (United States)

    Del Grosso, S. J.; Parton, W. J.; Ojima, D. S.; Mosier, A. R.; Mosier, A. R.; Paustian, K.; Peterson, G. A.

    2001-12-01

    We present maps showing regional patterns of land use change and soil C levels in the US Great Plains during the 20th century and time series of net greenhouse gas fluxes associated with different land uses. Net greenhouse gas fluxes were calculated by accounting for soil CO2 fluxes, the CO2 equivalents of N2O emissions and CH4 uptake, and the CO2 costs of N fertilizer production. Both historical and modern agriculture in this region have been net sources of greenhouse gases. The primary reason for this, prior to 1950, is that agriculture mined soil C and resulted in net CO2 emissions. When chemical N fertilizer became widely used in the 1950's agricultural soils began to sequester CO2-C but these soils were still net greenhouse gas sources if the effects of increased N2O emissions and decreased CH4 uptake are included. The sensitivity of net greenhouse gas fluxes to conventional and alternative land uses was explored using the DAYCENT ecosystem model. Model projections suggest that conversion to no-till, reduction of the fallow period, and use of nitrification inhibitors can significantly decrease net greenhouse gas emissions in dryland and irrigated systems, while maintaining or increasing crop yields.

  19. Development of an ensemble-adjoint optimization approach to derive uncertainties in net carbon fluxes

    Directory of Open Access Journals (Sweden)

    T. Ziehn

    2011-11-01

    Full Text Available Accurate modelling of the carbon cycle strongly depends on the parametrization of its underlying processes. The Carbon Cycle Data Assimilation System (CCDAS can be used as an estimator algorithm to derive posterior parameter values and uncertainties for the Biosphere Energy Transfer and Hydrology scheme (BETHY. However, the simultaneous optimization of all process parameters can be challenging, due to the complexity and non-linearity of the BETHY model. Therefore, we propose a new concept that uses ensemble runs and the adjoint optimization approach of CCDAS to derive the full probability density function (PDF for posterior soil carbon parameters and the net carbon flux at the global scale. This method allows us to optimize only those parameters that can be constrained best by atmospheric carbon dioxide (CO2 data. The prior uncertainties of the remaining parameters are included in a consistent way through ensemble runs, but are not constrained by data. The final PDF for the optimized parameters and the net carbon flux are then derived by superimposing the individual PDFs for each ensemble member. We find that the optimization with CCDAS converges much faster, due to the smaller number of processes involved. Faster convergence also gives us much increased confidence that we find the global minimum in the reduced parameter space.

  20. Net anthropogenic nitrogen inputs and nitrogen fluxes from Indian watersheds: An initial assessment

    Science.gov (United States)

    Swaney, D. P.; Hong, B.; Paneer Selvam, A.; Howarth, R. W.; Ramesh, R.; Purvaja, R.

    2015-01-01

    In this paper, we apply an established methodology for estimating Net Anthropogenic Nitrogen Inputs (NANI) to India and its major watersheds. Our primary goal here is to provide initial estimates of major nitrogen inputs of NANI for India, at the country level and for major Indian watersheds, including data sources and parameter estimates, making some assumptions as needed in areas of limited data availability. Despite data limitations, we believe that it is clear that the main anthropogenic N source is agricultural fertilizer, which is being produced and applied at a growing rate, followed by N fixation associated with rice, leguminous crops, and sugar cane. While India appears to be a net exporter of N in food/feed as reported elsewhere (Lassaletta et al., 2013b), the balance of N associated with exports and imports of protein in food and feedstuffs is sensitive to protein content and somewhat uncertain. While correlating watershed N inputs with riverine N fluxes is problematic due in part to limited available riverine data, we have assembled some data for comparative purposes. We also suggest possible improvements in methods for future studies, and the potential for estimating riverine N fluxes to coastal waters.

  1. Nutrient fluxes and net metabolism in a coastal lagoon SW peninsula of Baja California, Mexico

    Directory of Open Access Journals (Sweden)

    Cervantes Duarte, R.

    2016-09-01

    Full Text Available Fluxes of nutrients and net metabolism were estimated in coastal lagoon Magdalena Bay using LOICZ biogeochemical model. In situ data were obtained from 14 sites in the lagoon and also from a fixed site in the adjacent ocean area. Intense upwelling (February to July and faint upwelling (August to January were analyzed from monthly time series. The Temperature, nitrite + nitrate, ammonium and phosphate within the lagoon showed significant differences (p<0.05 between the two periods. Salinity (p=0.408 was more homogeneous (no significantly different due to mixing processes. During the intense upwelling period, nutrients increased in and out of the lagoon due to the influence of Transitional Water and Subartic Water transported by the California Current. However, during the faint upwelling, from August to January, the Transition Water and Subtropical Surface Water were predominant. Magdalena Bay showed denitrification processes of throughout the year as it occurred in other semi-arid coastal lagoons. It also showed a net autotrophic metabolism during intense upwelling and heterotrophic metabolism during faint upwelling. Understanding nutrient flows and net metabolism through simple biogeochemical models can provide tools for better management of the coastal zone.

  2. Solar magnetic fields - The generation of emerging flux

    Science.gov (United States)

    Golub, L.; Rosner, R.; Vaiana, G. S.; Weiss, N. O.

    1981-01-01

    X-ray observations have provided information about magnetic fields on the sun, and the implications of these observations are discussed. The pattern of small-scale flux emergence is quite different from that of active regions. It is inferred that the small-scale fields originate fairly high in the convective zone, while the fields in active regions have a deeper origin. The small-scale turbulent fields are only loosely related to the fields that define the normal solar cycle. The way in which dynamo models must be modified in the light of these results is indicated.

  3. Solar flare neon and solar cosmic ray fluxes in the past using gas-rich meteorites

    Science.gov (United States)

    Nautiyal, C. M.; Rao, M. N.

    1986-01-01

    Methods were developed earlier to deduce the composition of solar flare neon and to determine the solar cosmic ray proton fluxes in the past using etched lunar samples and at present, these techniques are extended to gas rich meteorites. By considering high temperature Ne data points for Pantar, Fayetteville and other gas rich meteorites and by applying the three component Ne-decomposition methods, the solar cosmic ray and galactic cosmic ray produced spallation Ne components from the trapped SF-Ne was resolved. Using appropiate SCR and GCR production rates, in the case of Pantar, for example, a GCR exposure age of 2 m.y. was estimated for Pantar-Dark while Pantar-Light yielded a GCR age of approx. 3 m.y. However the SCR exposure age of Pantar-Dark is two orders of magnitude higher than the average surface exposure ages of lunar soils. The possibility of higher proton fluxes in the past is discussed.

  4. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    Science.gov (United States)

    Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-01-01

    Abstract Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25. PMID:28781930

  5. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution.

    Science.gov (United States)

    Lockwood, Mike; Owens, Mathew J; Imber, Suzanne M; James, Matthew K; Bunce, Emma J; Yeoman, Timothy K

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.

  6. Net Fluorescein Flux Across Corneal Endothelium Strongly Suggests Fluid Transport is due to Electro-osmosis.

    Science.gov (United States)

    Sanchez, J M; Cacace, V; Kusnier, C F; Nelson, R; Rubashkin, A A; Iserovich, P; Fischbarg, J

    2016-08-01

    We have presented prior evidence suggesting that fluid transport results from electro-osmosis at the intercellular junctions of the corneal endothelium. Such phenomenon ought to drag other extracellular solutes. We have investigated this using fluorescein-Na2 as an extracellular marker. We measured unidirectional fluxes across layers of cultured human corneal endothelial (HCE) cells. SV-40-transformed HCE layers were grown to confluence on permeable membrane inserts. The medium was DMEM with high glucose and no phenol red. Fluorescein-labeled medium was placed either on the basolateral or the apical side of the inserts; the other side carried unlabeled medium. The inserts were held in a CO2 incubator for 1 h (at 37 °C), after which the entire volume of the unlabeled side was collected. After that, label was placed on the opposite side, and the corresponding paired sample was collected after another hour. Fluorescein counts were determined with a (Photon Technology) DeltaScan fluorometer (excitation 380 nm; emission 550 nm; 2 nm bwth). Samples were read for 60 s. The cells utilized are known to transport fluid from the basolateral to the apical side, just as they do in vivo in several species. We used 4 inserts for influx and efflux (total: 20 1-h periods). We found a net flux of fluorescein from the basolateral to the apical side. The flux ratio was 1.104 ± 0.056. That difference was statistically significant (p = 0.00006, t test, paired samples). The endothelium has a definite restriction at the junctions. Hence, an asymmetry in unidirectional fluxes cannot arise from osmosis, and can only point instead to paracellular solvent drag. We suggest, once more, that such drag is due to electro-osmotic coupling at the paracellular junctions.

  7. Is the flux of solar neutrinos correlated with the solar magnetic activity cycle

    Energy Technology Data Exchange (ETDEWEB)

    VanDeKop, T.; Snodgrass, H.B. (Lewis and Clark College, Portland, OR (United States))

    1993-01-01

    A number of recent investigations (eg. Bahcall and Press 1991, Ap. J. 370, 730) have found a weak anticorrelation between solar neutrino flux and sunspot number, but according to the electroweak model for the neutrino, there should be no coupling of neutrinos with such solar parameters as magnetic field strength; hence if the magnetic cycle is produced as the authors think it is (i.e. not connected to some periodicity in the Sun's nuclear reactor) no such correlation should exist. A convincing demonstration that a correlation between SNU and magnetic activity does exist would therefore constitute a major discovery, necessarily altering current understanding either of the physics taking place within the Sun or of the neutrino itself. Bahcall and Press, using the rank-order correlation method, determined that the anticorrelation of SNU with sunspot number is of significance during the period 1977-89. The authors have redone this project, extending the data base to include all data through 1992, and they find that inclusion of the additional data greatly reduces the correlation between SNU and the solar magnetic field strength itself. Results have been obtained using both the magnetic flux for the entire sun and that within bands of latitude of varying width along the line of sight to the solar core. Here, using the entire data set 1970-92, the authors find a significant correlation for which the significance varies with the band width, being greatest when the width approximates the core diameter.

  8. Procedure to determine module distribution within a solar array to increase the net energy collection in a solar competition vehicle

    Science.gov (United States)

    Suárez-Castañeda, Nicolás.; Gil-Herrera, Ana; Barrera-Velásquez, Jorge; Osorio-Gómez, Gilberto; Mejía-Gutiérrez, Ricardo

    2014-06-01

    In solar vehicle competition, the available space for installation of the solar panel in the car is limited. In order to optimize space, it is difficult not to install solar modules in areas impacted by shadows, even if they cause reduction of efficiency in the overall photoelectric generation. Shadow patterns arise from the relative position of the sun to the earth, and the relative position of the vehicle towards both of them. Since vehicle, earth and sun are moving in semi-predictable patterns, computer simulations can cross and match data from such sources to forecast generation behavior. The outputs of such simulations are shadow patterns on the surface of the vehicle, indicating locations that are suitable or unsuitable to install solar cells. This paper will show the design procedure of the solar panel for a Challenger Class solar vehicle that participated in the World Solar Challenge 2013, intended to increase the net energy collection. The results obtained, illustrate how the employment of a computational tool can help in the acquisition of both qualitative and quantitative information, related to shadows position and their impact on energy collection. With data inputs such as vehicle geometry and its relative position towards the route, the tool was used to evaluate different possible configurations of solar panel module distribution and select the ones that are more convenient to the given scenario. Therefore, this analysis allows improving the solar panel design by considering important variables that were often overlooked.

  9. Spillage and flux density on a receiver aperture lip. [of solar thermal collector

    Science.gov (United States)

    Jaffe, L. D.

    1985-01-01

    In a dish-type point-focusing solar thermal collector, the spillage and the flux density on the receiver aperture lip are related in a very simple way, if the aperture is circular and centered on the optical axis. Specifically, the flux density on the lip is equal to the spillage times the peak flux density in the plane of the lip.

  10. A wide-beam continuous solar simulator for simulating the solar flux at the orbit of Mercury

    Science.gov (United States)

    Thomas, N.; Beck, T.; Chakraborty, S.; Gerber, M.; Graf, S.; Piazza, D.; Roethlisberger, G.

    2011-06-01

    We report on the design, construction and testing of a wide-beam continuous solar simulator which can be used to simulate air mass zero (AM0) solar irradiance at fluxes of up to 6.5 solar constants. The instrument has been designed to produce a steady collimated beam with a homogeneous flux distribution across an aperture area of diameter 290 mm. The instrument is being used to test hardware designed to fly on the ESA/JAXA space mission to Mercury, BepiColombo. It has applications for other spacecraft missions which envisage passing inside the orbit of Venus (e.g. Solar Orbiter).

  11. Characteristics of heat flux and electromagnetic electron-cyclotron instabilities driven by solar wind electrons

    Science.gov (United States)

    Saeed, Sundas; Yoon, P. H.; Sarfraz, M.; Qureshi, M. N. S.

    2017-04-01

    In situ observations reveal the existence of electron velocity distribution function in the solar wind, where the net distribution can be modelled by a combination of core, halo and strahl. These components often possess a relative drift and with respective temperature anisotropies. The relative drift between the core and halo components leads to heat flux (HF) instability, while temperature anisotropies drive electromagnetic electron-cyclotron (EMEC) instability. These instabilities have been separately studied in the literature, but for the first time, the present study combines both unstable modes in the presence of two free energy sources, namely, excessive parallel pressure and excessive perpendicular temperature. HF instability (which is a left-hand circularly polarized mode) is effectively similar to electron firehose instability, except that the free energy is provided by net relative drift among two component electrons in the background of protons. The HF instability is discussed here along with (the right-hand polarized) EMEC instability driven by temperature anisotropy. The unstable HF mode is conventionally termed the 'whistler' HF instability, but it is actually polarized in the opposite sense to the whistler wave. EMEC mode, on the other hand, reduces to the proper whistler wave in the absence of free energy source. The present combined analysis clarifies the polarization characteristics of these two modes in an unambiguous manner.

  12. MetaFluxNet, a program package for metabolic pathway construction and analysis, and its use in large-scale metabolic flux analysis of Escherichia coli.

    Science.gov (United States)

    Lee, Sang Yup; Lee, Dong-Yup; Hong, Soon Ho; Kim, Tae Yong; Yun, Hongsoek; Oh, Young-Gyun; Park, Sunwon

    2003-01-01

    We have developed MetaFluxNet which is a stand-alone program package for the management of metabolic reaction information and quantitative metabolic flux analysis. It allows users to interpret and examine metabolic behavior in response to genetic and/or environmental modifications. As a result, quantitative in silico simulations of metabolic pathways can be carried out to understand the metabolic status and to design the metabolic engineering strategies. The main features of the program include a well-developed model construction environment, user-friendly interface for metabolic flux analysis (MFA), comparative MFA of strains having different genotypes under various environmental conditions, and automated pathway layout creation. The usefulness and functionality of the program are demonstrated by applying to metabolic pathways in E. coli. First, a large-scale in silico E. coli model is constructed using MetaFluxNet, and then the effects of carbon sources on intracellular flux distributions and succinic acid production were investigated on the basis of the uptake and secretion rates of the relevant metabolites. The results indicated that among three carbon sources available, the most reduced substrate is sorbitol which yields efficient succinic acid production. The software can be downloaded from http://mbel.kaist.ac.kr/.

  13. Derivation of Surface Net Radiation at the Valencia Anchor Station from Top of the Atmosphere Gerb Fluxes by Means of Linear Models and Neural Networks

    Science.gov (United States)

    Geraldo Ferreira, A.; Lopez-Baeza, Ernesto; Velazquez Blazquez, Almudena; Soria-Olivas, Emilio; Serrano Lopez, Antonio J.; Gomez Chova, Juan

    2012-07-01

    In this work, Linear Models (LM) and Artificial Neural Networks (ANN) have been developed to estimate net radiation (RN) at the surface. The models have been developed and evaluated by using the synergy between Geostationary Earth Radiation Budget (GERB-1) and Spinning Enhanced Visible and Infrared Imager (SEVIRI) data, both instruments onboard METEOSAT-9, and ``in situ'' measurements. The data used in this work, corresponding to August 2006 and June to August 2007, proceed from Top of the Atmosphere (TOA) broadband fluxes from GERB-1, every 15 min, and from net radiation at the surface measured, every 10 min, at the Valencia Anchor Station (VAS) area, having measured independently the shortwave and the longwave radiation components (downwelling and upwelling) for different land uses and land cover. The adjustment of both temporal resolutions for the satellite and in situ data was achieved by linear interpolation that showed less standard deviation than the cubic one. The LMs were developed and validated by using satellite TOA RN and ground station surface RN measurements, only considering cloudy free days selected from the ground data. The ANN model was developed both for cloudy and cloudy-free conditions using seven input variables selected for the training/validation sets, namely, hour, day, month, surface RN, solar zenith angle and TOA shortwave and longwave fluxes. Both, LMs and ANNs show remarkably good agreement when compared to surface RN measurements. Therefore, this methodology can be successfully applied to estimate RN at surface from GERB/SEVIRI data.

  14. High-flux solar furnace processing of crystalline silicon solar cells

    Science.gov (United States)

    Tsuo, Y. S.; Pitts, J. R.; Menna, P.; Landry, M. D.; Gee, J. M.; Ciszek, T. F.

    1997-02-01

    We studied the processing of crystalline-silicon solar cells using a 10-kW, high-flux solar furnace (HFSF). Major findings of this study include: (1) hydrogenated amorphous silicon films deposited on glass substrates can be converted to microcrystalline silicon by solid-phase crystallization in 5 seconds or less in the HFSF; (2) the presence of concentrated sunlight enhances the diffusion of phosphorus into silicon from a spin-on dopant source; (3) the combination of a porous-silicon surface layer and photo-enhanced impurity diffusion is very effective in gettering impurities from a metallurgical-grade silicon wafer or thin-layer silicon deposited using liquid-phase epitaxy; (4) a 14.1%-efficient crystalline-silicon solar cell with an area of 4.6 cm2 was fabricated using the HFSF for simultaneous diffusion of front n+-p and back p-p+ junctions; and (5) we have shown that the HFSF can be used to texture crystalline-silicon surfaces and to anneal metal contacts printed on a silicon solar cell.

  15. Why and when channelling can decrease pool size at constant net flux in a simple dynamic channel.

    Science.gov (United States)

    Mendes, P; Kell, D B; Westerhoff, H V

    1996-03-15

    Cornish-Bowden and Cárdenas (Cornish-Bowden, A. and Cárdenas M.L. (1993) Eur. J. Biochem. 213, 87-92) have suggested that simulation results peviously published by us (Mendes, P., Kell, D.B. and Westerhoff, H.V. (1992) Eur. J. Biochem. 204, 255-266) which had demonstrated that large reductions of intermediate pool sizes could be accompanied by increasing channel flux in a model metabolic pathway, were an artefact of changes in the pathway's overall flux of the order of 0.0075%, or of inappropriate alterations of enzyme activities. They also asserted to prove that the "channelling of an intermediate cannot affect its free concentration at constant net flux". We consider the co-response of the intermediate metabolite concentration ('pool') and the channel flux to changes in kinetic (or thermodynamic) parameters. Both by analytical proofs and by numerical examples we show that this co-response can be positive, negative or null, depending on the parameter change. In particular, we prove that there is always a number of ways of changing parameters such that the intermediate metabolite concentration decreases with increasing channel flux, whether the total flux varies or is constant. We also show that increased stability of the (dynamic) enzyme-intermediate-enzyme complex, as well as a single parameter change that similarly displays no cross-over effects, can lead to decreased intermediate metabolite concentration and increased channel flux at constant total flux. In general, a non-zero co-response of the intermediate metabolite concentration ('pool') and the channel flux to changes in kinetic (or other) parameters is the rule rather than the exception. More specifically: (i) The algebraic analysis ('general proof') given in Cornish-Bowden and Cárdenas (1993) contains the constraint that the elasticities of various steps to the modulation parameters which were used to vary the channel flux at constant net flux were unity. This is an unfortunate and unnecessary

  16. Solar Modulation of Inner Trapped Belt Radiation Flux as a Function of Atmospheric Density

    Science.gov (United States)

    Lodhi, M. A. K.

    2005-01-01

    No simple algorithm seems to exist for calculating proton fluxes and lifetimes in the Earth's inner, trapped radiation belt throughout the solar cycle. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in Cycle 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton fluxes at any time in a given solar cycle, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From flux and its time integral fluence, one can then approximate dose rate and its time integral dose.

  17. Eddy covariance flux measurements of net ecosystem carbon dioxide exchange from a lowland peatland flux tower network in England and Wales

    Science.gov (United States)

    Morrison, Ross; Balzter, Heiko; Burden, Annette; Callaghan, Nathan; Cumming, Alenander; Dixon, Simon; Evans, Jonathan; Kaduk, Joerg; Page, Susan; Pan, Gong; Rayment, Mark; Ridley, Luke; Rylett, Daniel; Worrall, Fred; Evans, Christopher

    2016-04-01

    Peatlands store disproportionately large amounts of soil carbon relative to other terrestrial ecosystems. Over recent decades, the large amount of carbon stored as peat has proved vulnerable to a range of land use pressures as well as the increasing impacts of climate change. In temperate Europe and elsewhere, large tracts of lowland peatland have been drained and converted to agricultural land use. Such changes have resulted in widespread losses of lowland peatland habitat, land subsidence across extensive areas and the transfer of historically accumulated soil carbon to the atmosphere as carbon dioxide (CO2). More recently, there has been growth in activities aiming to reduce these impacts through improved land management and peatland restoration. Despite a long history of productive land use and management, the magnitude and controls on greenhouse gas emissions from lowland peatland environments remain poorly quantified. Here, results of surface-atmosphere measurements of net ecosystem CO2 exchange (NEE) from a network of seven eddy covariance (EC) flux towers located at a range of lowland peatland ecosystems across the United Kingdom (UK) are presented. This spatially-dense peatland flux tower network forms part of a wider observation programme aiming to quantify carbon, water and greenhouse gas balances for lowland peatlands across the UK. EC measurements totalling over seventeen site years were obtained at sites exhibiting large differences in vegetation cover, hydrological functioning and land management. The sites in the network show remarkable spatial and temporal variability in NEE. Across sites, annual NEE ranged from a net sink of -194 ±38 g CO2-C m-2 yr-1 to a net source of 784±70 g CO2-C m-2 yr-1. The results suggest that semi-natural sites remain net sinks for atmospheric CO2. Sites that are drained for intensive agricultural production range from a small net sink to the largest observed source for atmospheric CO2 within the flux tower network

  18. Solar array design based on shadow analysis for increasing net energy collection in a competition vehicle

    Science.gov (United States)

    Osorio-Gómez, Gilberto; Mejía-Gutiérrez, Ricardo; Suárez-Castañeda, Nicolás; Gil-Herrera, Ana; Barrera-Velásquez, Jorge

    2015-01-01

    Photovoltaic (PV) applications such as in the architectural, automotive, and aerospace industries face design contradictions because they are expected to produce a lot of energy but are constrained by available area, surface shape, incident irradiance, shadows, and other aspects that have a negative influence on the energy produced by the solar panel. Solar competition vehicles are some of these challenging PV applications. The design of such solar arrays needs to consider efficiency evaluation in order to optimize space; it is difficult not to install solar modules in areas impacted by shadows. A design procedure for a solar array configuration based on shadow analysis for competition vehicles is presented. The principle is that shadows in moving objects can be simulated, since the vehicle, the earth and the sun are are moving in semipredictable patterns, thus net energy collection can be forecast. The case study presented is the solar array design of a vehicle that participated in the World Solar Challenge 2013. The obtained results illustrate how the employment of the procedure gives insights on important aspects to consider and also delivers qualitative and quantitative information for decision making. In addition, the experience in competition highlights some issues to be considered, modified, or improved in further vehicle designs.

  19. Estimation of net ecosystem carbon exchange for the conterminous United States by combining MODIS and AmeriFlux data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Bolstad, Paul V.; Burns, Sean P.; Chen, Jiquan; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Law, Beverly E.; Litvak, Marcy; Ma, Siyan; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Noormets, Asko; Oechel, Walter C.; Oren, Ram; Richardson, Andrew D.; Schmid, Hans Peter; Scott, Russell L.; Starr, Gregory; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.; Paw, Kyaw; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.

    2008-10-01

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board the National Aeronautics and Space Administration's (NASA) Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a modified regression tree approach. The predictive model was trained and validated using eddy flux NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE well (r = 0.73, p < 0.001). We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day interval in 2005 using spatially explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE as determined from measurements and the literature. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets over large areas.

  20. Nimbus-7 Solar and Earth Flux Data in Native Binary Format

    Data.gov (United States)

    National Aeronautics and Space Administration — The NIMBUS7_ERB_SEFDT data set is the Solar and Earth Flux Data Tape (SEFDT) generated from Nimbus-7 Earth Radiation Budget (ERB) instrument data. The main purpose...

  1. Sounding rocket measurement of the absolute solar EUV flux utilizing a silicon photodiode

    Science.gov (United States)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Canfield, L. R.

    1990-01-01

    A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.

  2. A more accurate formula for calculating the net longwave radiation flux in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Tomasz Zapadka

    2007-12-01

    Full Text Available A new, more accurate formula for calculating the net longwave radiation fluxLW ↑↓ has been devised for the Baltic Sea region. To this end,the following sets of simultaneously measured data regarding the longwave radiation of the sea andthe atmosphere were used: the temperatures of the sea surface and its contiguous air layer,the water vapour pressure in the air above the water, and the cloud cover.These data were gathered during numerous research cruises in the Baltic in 2000-03 and were supplemented by satellitedata from Karlsson (2001 characterising the cloud cover over the whole Baltic. The formulaestablished for LW ↑↓ can be written in the form of three alternative equations,differing with respect to their cloud cover functions:LW ↑↓ =0.985σT4s - σT4a (0.685+0.00452e{(1 + d n2 average for all cloud types (Z1(1 + din2 separately for low-, mid- and high-level clouds (Z2(1 + dinϒi separately for low-, mid- and high-level clouds (Z3where σ - Stefan-Boltzmann constant; Ts - sea surface temperature [K]; Ta - air temperature [K]; e - water vapour pressure [mbar]; n - total cloud amount [0 - 1]; d - mean empirical dimensionless coefficient, determined for all cloud types or for particular months (see Tables 3 and 4; da - empirical coefficient determined for the quadratic function: d1 = 0.39 for low-level clouds, d2 = 0.305 for mid-level clouds, d3 = 0.22 for high-level clouds; di - empirical coefficient determined as follows: d1 = 0.39 for low-level clouds when γ1 = 1.3, d2 = 0.29 for mid-level clouds when γ2 = 1.1; d3 = 0.17 for high-level clouds when γ3 = 0.96. The improved accuracy of this formula (RMSE ≅ 10 W m-2 is due chiefly to the establishment of functions and coefficients characterising the cloud cover over the Baltic in particular months of the year and their incorporation into it.

  3. Evaluation and uncertainty analysis of regional-scale CLM4.5 net carbon flux estimates

    Science.gov (United States)

    Post, Hanna; Hendricks Franssen, Harrie-Jan; Han, Xujun; Baatz, Roland; Montzka, Carsten; Schmidt, Marius; Vereecken, Harry

    2018-01-01

    Modeling net ecosystem exchange (NEE) at the regional scale with land surface models (LSMs) is relevant for the estimation of regional carbon balances, but studies on it are very limited. Furthermore, it is essential to better understand and quantify the uncertainty of LSMs in order to improve them. An important key variable in this respect is the prognostic leaf area index (LAI), which is very sensitive to forcing data and strongly affects the modeled NEE. We applied the Community Land Model (CLM4.5-BGC) to the Rur catchment in western Germany and compared estimated and default ecological key parameters for modeling carbon fluxes and LAI. The parameter estimates were previously estimated with the Markov chain Monte Carlo (MCMC) approach DREAM(zs) for four of the most widespread plant functional types in the catchment. It was found that the catchment-scale annual NEE was strongly positive with default parameter values but negative (and closer to observations) with the estimated values. Thus, the estimation of CLM parameters with local NEE observations can be highly relevant when determining regional carbon balances. To obtain a more comprehensive picture of model uncertainty, CLM ensembles were set up with perturbed meteorological input and uncertain initial states in addition to uncertain parameters. C3 grass and C3 crops were particularly sensitive to the perturbed meteorological input, which resulted in a strong increase in the standard deviation of the annual NEE sum (σ ∑ NEE) for the different ensemble members from ˜ 2 to 3 g C m-2 yr-1 (with uncertain parameters) to ˜ 45 g C m-2 yr-1 (C3 grass) and ˜ 75 g C m-2 yr-1 (C3 crops) with perturbed forcings. This increase in uncertainty is related to the impact of the meteorological forcings on leaf onset and senescence, and enhanced/reduced drought stress related to perturbation of precipitation. The NEE uncertainty for the forest plant functional type (PFT) was considerably lower (σ ∑ NEE ˜ 4.0-13.5 g C

  4. An experimental investigation of flows from zero-net mass-flux actuators

    Science.gov (United States)

    Holman, Ryan Jay

    Zero-net mass-flux (ZNMF) devices consist of an oscillating driver, a cavity, and a small opening such as a rectangular slot or a circular orifice. The driver produces a series of vortex pairs (or rings) at the slot/orifice which add momentum and circulation to the flow. ZNMF devices are useful tools for flow control applications such as heat transfer, mixing enhancement, and boundary layer separation control. To date much research has been done to qualify and quantify the effects of ZNMF devices in many applications, both experimental and computational. However, a number of issues still remain. First, there is no universally accepted dimensionless parameter space, which makes device characterization and comparison between studies difficult. Second, most experimental studies do not sufficiently quantify the nearfield behavior, which hinders the fundamental understanding of the underlying flow physics. Of particular interest are the regimes of jet formation, and transition from laminar to turbulent-like flow, which are not well understood. Finally, the accuracy of experimental measurements are seldom reported in the literature. This study unifies the experimental and numerical data presented in the literature for ZNMF flowfields exhausting into a quiescent medium. A quantitative experimental database is also generated to completely characterize the topological regions of ZNMF flows over a useful range of the dimensionless parameter space. The database is derived chiefly from two-dimensional velocity field measurements using particle image velocimetry and laser Doppler anemometry. Vorticity, circulation, Reynolds stress, and turbulent kinetic energy is acquired to characterize the resulting flowfield. Significant insight into the behavior of voice coil driven ZNMF devices is uncovered. Design improvements are made by implementing a sinusoidal controller for piston motion and eliminating the need for a sealing membrane in the cavity. It is shown that the proper

  5. Direct Heat-Flux Measurement System (MDF) for Solar central Receiver Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Ballestrin, J.

    2001-07-01

    A direct flux measurement system, MDF, has been designed, constructed and mounted on top of the SSPS-CRS tower at the Plataforma Solar de Almeria (PSA) in addition to an indirect flux measurement system based on a CCD camera. It's one of the main future objectives to compare systematically both measurements of the concentrated solar power, increasing in this way the confidence in the estimate of this quantity. Today everything is prepared to perform the direct flux measurement on the aperture of solar receivers: calorimeter array, data acquisition system and software. the geometry of the receiver determines the operation and analysis procedures to obtain the indecent power onto the defined area. The study of previous experiences with direct flux measurement systems ha been useful to define a new simpler and more accurate system. A description of each component of the MDF system is included, focusing on the heat-flux sensors or calorimeters, which enables these measurements to be done in a few seconds without water-cooling. The incident solar power and the spatial flux distribution on the aperture of the volumetric receiver Hitrec II are supplied by the above-mentioned MDF system. The first results obtained during the evaluation of this solar receiver are presented including a sunrise-sunset test. All these measurements have been concentrated in one coefficient that describes the global behavior of the Solar Power Plant. (Author) 18 refs.

  6. Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Herrero, Raúl; Hidalgo, Miguel A.; Carcaboso, Fernando; Blanco, Juan J. [Dpto. de Física y Matemáticas, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid (Spain); Dresing, Nina; Klassen, Andreas; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, University of Kiel, D-24118, Kiel (Germany); Temmer, Manuela; Veronig, Astrid [Institute of Physics/Kanzelhöhe Observatory, University of Graz, A-8010 Graz (Austria); Bučík, Radoslav [Institut für Astrophysik, Georg-August-Universität Göttingen, D-37077, Göttingen (Germany); Lario, David, E-mail: raul.gomezh@uah.es [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States)

    2017-05-10

    On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation times are consistent with a low number of field line rotations N < 5 of the flux rope between the Sun and 1 au. The flux rope model used in this work suggests an even lower number of rotations.

  7. Deciphering the components of regional net ecosystem fluxes following a bottom-up approach for the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    N. Carvalhais

    2010-11-01

    Full Text Available Quantification of ecosystem carbon pools is a fundamental requirement for estimating carbon fluxes and for addressing the dynamics and responses of the terrestrial carbon cycle to environmental drivers. The initial estimates of carbon pools in terrestrial carbon cycle models often rely on the ecosystem steady state assumption, leading to initial equilibrium conditions. In this study, we investigate how trends and inter-annual variability of net ecosystem fluxes are affected by initial non-steady state conditions. Further, we examine how modeled ecosystem responses induced exclusively by the model drivers can be separated from the initial conditions. For this, the Carnegie-Ames-Stanford Approach (CASA model is optimized at set of European eddy covariance sites, which support the parameterization of regional simulations of ecosystem fluxes for the Iberian Peninsula, between 1982 and 2006.

    The presented analysis stands on a credible model performance for a set of sites, that represent generally well the plant functional types and selected descriptors of climate and phenology present in the Iberian region – except for a limited Northwestern area. The effects of initial conditions on inter-annual variability and on trends, results mostly from the recovery of pools to equilibrium conditions; which control most of the inter-annual variability (IAV and both the magnitude and sign of most of the trends. However, by removing the time series of pure model recovery from the time series of the overall fluxes, we are able to retrieve estimates of inter-annual variability and trends in net ecosystem fluxes that are quasi-independent from the initial conditions. This approach reduced the sensitivity of the net fluxes to initial conditions from 47% and 174% to −3% and 7%, for strong initial sink and source conditions, respectively.

    With the aim to identify and improve understanding of the component fluxes that drive the observed trends, the

  8. Estimation of Net Ecosystem Carbon Exchange for the Conterminous UnitedStates by Combining MODIS and AmeriFlux Data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Law, Beverly E.; Richardson, Andrew D.; Chen, Jiquan; Oren, Ram; Starr, Gregory; Noormets, Asko; Ma, Siyan; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.; Bolstad, Paul V.; Burns, Sean P.; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Falk, Matthias; Fischer, Marc L.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Litvak, Marcy; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Oechel, Walter C.; U, Kyaw Tha Paw; Schmid, Hans Peter; Scott, Russell L.; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.

    2009-03-06

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely-sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board NASA's Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a regression tree approach. The predictive model was trained and validated using NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE reasonably well at the site level. We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day period in 2005 using spatially-explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets for large areas.

  9. Solar Open Flux Migration from Pole to Pole: Magnetic Field Reversal.

    Science.gov (United States)

    Huang, G-H; Lin, C-H; Lee, L C

    2017-08-25

    Coronal holes are solar regions with low soft X-ray or low extreme ultraviolet intensities. The magnetic fields from coronal holes extend far away from the Sun, and thus they are identified as regions with open magnetic field lines. Coronal holes are concentrated in the polar regions during the sunspot minimum phase, and spread to lower latitude during the rising phase of solar activity. In this work, we identify coronal holes with outward and inward open magnetic fluxes being in the opposite poles during solar quiet period. We find that during the sunspot rising phase, the outward and inward open fluxes perform pole-to-pole trans-equatorial migrations in opposite directions. The migration of the open fluxes consists of three parts: open flux areas migrating across the equator, new open flux areas generated in the low latitude and migrating poleward, and new open flux areas locally generated in the polar region. All three components contribute to the reversal of magnetic polarity. The percentage of contribution from each component is different for different solar cycle. Our results also show that the sunspot number is positively correlated with the lower-latitude open magnetic flux area, but negatively correlated with the total open flux area.

  10. The influence of cockchafer larvae on net soil methane fluxes under different vegetation types - a mesocosm study

    Science.gov (United States)

    Görres, Carolyn-Monika; Kammann, Claudia; Chesmore, David; Müller, Christoph

    2017-04-01

    The influence of land-use associated pest insects on net soil CH4 fluxes has received little attention thus far, although e.g. soil-dwelling Scarabaeidae larvae are qualitatively known to emit CH4. The project "CH4ScarabDetect" aims to provide the first quantitative estimate of the importance of soil-dwelling larvae of two important European agricultural and forest pest insect species - the common cockchafer (Melolontha melolontha) and the forest cockchafer (M. hippocastani) - for net soil CH4 fluxes. Here we present a mesocosm study within "CH4ScarabDetect" which tests the influence of different abundances of common cockchafer larvae on net soil CH4 fluxes under different vegetation types. In August 2016, 27 PVC boxes with a base area of 50 cm x 50 cm and a height of 40 cm were buried in planting beds previously used for cultivating vegetables. The bottom of each box was filled with a 10 cm thick layer of loam which was then covered with a 25 cm thick layer of loamy sand. The soil was hand-sieved prior to filling the boxes to remove any macrofauna. The mesocosms were planted with either turf, carrots or a combination of both. Of the resulting nine replicates per vegetation type, six were infested with one cockchafer larvae each in November 2016. In three of these infested mesocosms, the larvae abundance will be further increased to three in May 2017. This mesocosm study will continue until October 2017 during which measurements of net soil CH4 fluxes will be conducted with the chamber flux method twice per month. For the in situ separation of gross CH4 production and gross CH4 oxidation, the chamber method will be combined with a 13CH4 isotope pool dilution technique. Methane concentrations and their isotopic signatures in the collected gas samples will be analysed with a state-of-the-art CRDS analyzer (cavity ring-down spectroscopy, G2201-i) equipped with the Small Sample Isotope Module 2 - A0314 (Picarro Inc., USA). Different combinations of larvae abundance and

  11. Exploring the Flux Tube Paradigm in Solar-like Convection Zones

    Science.gov (United States)

    Weber, Maria A.; Nelson, Nicholas; Browning, Matthew

    2017-08-01

    In the solar context, important insight into the flux emergence process has been obtained by assuming the magnetism giving rise to sunspots consists partly of idealized flux tubes. Global-scale dynamo models are only now beginning to capture some aspects of flux emergence. In certain regimes, these simulations self-consistently generate magnetic flux structures that rise buoyantly through the computational domain. How similar are these dynamo-generated, rising flux structures to traditional flux tube models? The work we present here is a step toward addressing this question. We utilize the thin flux tube (TFT) approximation to simply model the evolution of flux tubes in a global, three-dimensional geometry. The TFTs are embedded in convective flows taken from a global dynamo simulation of a rapidly rotating Sun within which buoyant flux structures arise naturally from wreaths of magnetism. The initial conditions of the TFTs are informed by rising flux structures identified in the dynamo simulation. We compare the trajectories of the dynamo-generated flux loops with those computed through the TFT approach. We also assess the nature of the relevant forces acting on both sets of flux structures, such as buoyancy, the Coriolis force, and external forces imparted by the surrounding convection. To achieve the fast Law trend of active regions. Our work aims to provide constraints, and possible calibrations, on the traditional flux tube model as it pertains to the Sun and other spotted stars.

  12. Inferring CO2 Fluxes from OCO-2 for Assimilation into Land Surface Models to Calculate Net Ecosystem Exchange

    Science.gov (United States)

    Prouty, R.; Radov, A.; Halem, M.; Nearing, G. S.

    2016-12-01

    Investigations of mid to high latitude atmospheric CO2 show a growing seasonal amplitude. Land surface models poorly predict net ecosystem exchange (NEE) and are unable to substantiate these sporadic observations. An investigation of how the biosphere has reacted to changes in atmospheric CO2 is essential to our understanding of potential climate-vegetation feedbacks. A global, seasonal investigation of CO2-flux is then necessary in order to assimilate into land surface models for improving the prediction of annual NEE. The Atmospheric Radiation Measurement program (ARM) of DOE collects CO2-flux measurements (in addition to CO2 concentration and various other meteorological quantities) at several towers located around the globe at half hour temporal frequencies. CO2-fluxes are calculated via the eddy covariance technique, which utilizes CO2-densities and wind velocities to calculate CO2-fluxes. The global coverage of CO2 concentrations as provided by the Orbiting Carbon Observatory (OCO-2) provide satellite-derived CO2 concentrations all over the globe. A framework relating the satellite-inferred CO2 concentrations collocated with the ground-based ARM as well as Ameriflux stations would enable calculations of CO2-fluxes far from the station sites around the entire globe. Regression techniques utilizing deep-learning neural networks may provide such a framework. Additionally, meteorological reanalysis allows for the replacement of the ARM multivariable meteorological variables needed to infer the CO2-fluxes. We present the results of inferring CO2-fluxes from OCO-2 CO2 concentrations for a two year period, Sept. 2014- Sept. 2016 at the ARM station located near Oklahoma City. A feed-forward neural network (FFNN) is used to infer relationships between the following data sets: F([ARM CO2-density], [ARM Meteorological Data]) = [ARM CO2-Flux] F([OCO-2 CO2-density],[ARM Meteorological Data]) = [ARM CO2-Flux] F([ARM CO2-density],[Meteorological Reanalysis]) = [ARM CO2-Flux

  13. Dietary supplementation of branched-chain amino acids increases muscle net amino acid fluxes through elevating their substrate availability and intramuscular catabolism in young pigs.

    Science.gov (United States)

    Zheng, Liufeng; Zuo, Fangrui; Zhao, Shengjun; He, Pingli; Wei, Hongkui; Xiang, Quanhang; Pang, Jiaman; Peng, Jian

    2017-04-01

    Branched-chain amino acids (BCAA) have been clearly demonstrated to have anabolic effects on muscle protein synthesis. However, little is known about their roles in the regulation of net AA fluxes across skeletal muscle in vivo. This study was aimed to investigate the effect and related mechanisms of dietary supplementation of BCAA on muscle net amino acid (AA) fluxes using the hindlimb flux model. In all fourteen 4-week-old barrows were fed reduced-protein diets with or without supplemental BCAA for 28 d. Pigs were implanted with carotid arterial, femoral arterial and venous catheters, and fed once hourly with intraarterial infusion of p-amino hippurate. Arterial and venous plasma and muscle samples were obtained for the measurement of AA, branched-chain α-keto acids (BCKA) and 3-methylhistidine (3-MH). Metabolomes of venous plasma were determined by HPLC-quadrupole time-of-flight-MS. BCAA-supplemented group showed elevated muscle net fluxes of total essential AA, non-essential AA and AA. As for individual AA, muscle net fluxes of each BCAA and their metabolites (alanine, glutamate and glutamine), along with those of histidine, methionine and several functional non-essential AA (glycine, proline and serine), were increased by BCAA supplementation. The elevated muscle net AA fluxes were associated with the increase in arterial and intramuscular concentrations of BCAA and venous metabolites including BCKA and free fatty acids, and were also related to the decrease in the intramuscular concentration of 3-MH. Correlation analysis indicated that muscle net AA fluxes are highly and positively correlated with arterial BCAA concentrations and muscle net BCKA production. In conclusion, supplementing BCAA to reduced-protein diet increases the arterial concentrations and intramuscular catabolism of BCAA, both of which would contribute to an increase of muscle net AA fluxes in young pigs.

  14. [Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

    Science.gov (United States)

    Zheng, You-Fei; Ni, Yan-Li; Mai, Bo-Ru; Wu, Rong-Jun; Feng, Yan; Sun, Jian; Li, Jian; Xu, Jing-Xin

    2011-06-01

    Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

  15. Dependence of thermospheric zonal winds on solar flux, geomagnetic activity, and hemisphere as measured by CHAMP

    Science.gov (United States)

    Zhang, Xiaofang; Liu, Libo; Liu, Songtao

    2017-08-01

    The thermospheric zonal winds measured by the CHAllenging Minisatellite Payload (CHAMP) satellite are used to statistically determine the climatology under quiet and active geomagnetic conditions. By collectively analyzing the bin-averaged wind trend with F10.7 and the solar-induced difference in wind structures, the solar flux dependence of global thermosphere zonal wind is determined. The increase of solar flux enhances the eastward winds at low latitudes from dusk to midnight. The increased ion drag reduces the nighttime eastward wind in the subauroral latitudes, and the daytime westward winds from 06 to 08 MLT at all latitudes decrease with increasing solar flux. Zonal winds show coupled seasonal/extreme ultraviolet (EUV) dependency. The equatorial zonal winds from 18 to 04 magnetic local time (MLT) indicate weaker eastward winds during the June solstice at high solar flux levels. Quiet time eastward winds at subauroral latitudes from 16 to 20 MLT are further decreased in the winter hemisphere. Influenced by asymmetries in solar illumination and the magnetic field, zonal winds show hemispheric asymmetries. Quiet daytime winds are additionally influenced by solar illumination effects, and the westward winds at the middle and subauroral latitudes are always stronger in the summer. The nighttime eastward winds are higher in the winter hemisphere during the solstices, as in the Southern Hemisphere during equinoxes, with the winter-summer asymmetry lessened or receding at the solar maxima. Storm-induced subauroral westward disturbance winds are higher in the summer hemisphere and in the Northern Hemisphere during equinoxes. At a high level of solar flux, the westward disturbance winds are comparable in the two hemispheres during December solstice. Geomagnetic disturbance wind observations from CHAMP agree well with the empirical geomagnetic disturbance wind model, except for stronger subauroral westward jets. Westward winds during the afternoon may be enhanced in

  16. Net primary production and seasonal CO2 and CH4 fluxes in a Trapa natans L. meadow

    Directory of Open Access Journals (Sweden)

    Marco BARTOLI

    2010-08-01

    Full Text Available The main hypothesis of this work is that Trapa natans L. and similar floating leaved macrophytes are only temporary sinks of atmospheric carbon dioxide and that they favour water hypoxia and large methane efflux from sediment to the atmosphere, due to their shading effect and scarce ability to transfer oxygen to submerged tissues. For this purpose, from April to August 2005, T. natans production, dissolved O2, CO2 and CH4 concentrations in the water column and CO2 and CH4 fluxes across the wateratmosphere interface were measured in an oxbow lake (Lanca di Po, Northern Italy where a monospecific floating mat of water chestnut develops. Net primary production by T. natans was determined via biomass harvesting while gas fluxes were determined via short-term incubations of light and dark floating chambers. From July onwards, when the water surface of the oxbow lake was entirely colonized by the plant, the dense canopy resulted in a physical barrier for light and water reareation. As a consequence of sediment and plant respiration, persistent hypoxia and often anoxia, and CO2 and CH4 supersaturation occurred in the water column. Net primary production of T. natans, calculated at peak biomass, was 13.05 ± 0.32 mol CO2 m-2. The T. natans mat was a net sink for atmospheric CO2 from mid June to mid August, with an uptake peak measured at the beginning of July (229 mmol m-2 d-1; estimated net ecosystem metabolism was ≤10.09 ± 1.90 mol CO2 m-2. Contextually, during the vegetative period of T. natans, the oxbow lake was a net source of methane (9.52 ± 2.10 mol m-2, and the resulting CH4 to CO2 flux ratio across the water-atmosphere interface was ≥0.94. The large methane release was probably due to the persistent hypoxia and anoxia induced by the T. natans meadow, which uncoupled methane production from methane oxidation.

  17. Modeling of Drift Effects on Solar Tower Concentrated Flux Distributions

    Directory of Open Access Journals (Sweden)

    Luis O. Lara-Cerecedo

    2016-01-01

    Full Text Available A novel modeling tool for calculation of central receiver concentrated flux distributions is presented, which takes into account drift effects. This tool is based on a drift model that includes different geometrical error sources in a rigorous manner and on a simple analytic approximation for the individual flux distribution of a heliostat. The model is applied to a group of heliostats of a real field to obtain the resulting flux distribution and its variation along the day. The distributions differ strongly from those obtained assuming the ideal case without drift or a case with a Gaussian tracking error function. The time evolution of peak flux is also calculated to demonstrate the capabilities of the model. The evolution of this parameter also shows strong differences in comparison to the case without drift.

  18. Design of advanced solar homes aimed at net-zero annual energy consumption in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Athienitis, Andreas

    2010-09-15

    This paper overviews the design of three sustainable low or net-zero energy solar homes in Canada. The major features of the houses are: 1. direct gain passive solar design that emphasizes utilization of distributed thermal mass in the equatorial-facing part of the ground floor; 2. a building-integrated photovoltaic-thermal system (BIPV/T); 3. a two-stage ground-source heat pump used to heat/cool air in the house or an air source heat pump using BIPV/T air as the source to heat a storage tank; 4. a floor heating system integrated in the floor mass of the direct gain zone; 5. a multizone programmable thermostat.

  19. Influence of the solar EUV flux on the Martian plasma environment

    Directory of Open Access Journals (Sweden)

    R. Modolo

    2005-02-01

    Full Text Available The interaction of the solar wind with the Martian atmosphere and ionosphere is investigated by using three-dimensional, global and multi-species hybrid simulations. In the present work we focus on the influence of the solar EUV flux on the Martian plasma environment by comparing simulations done for conditions representative of the extrema of the solar cycle. The dynamics of four ionic species (H+, He++, O+, O2+, originating either from the solar wind or from the planetary plasma, is treated fully kinetically in the simulation model in order to characterize the distribution of each component of the plasma, both at solar maximum and at solar minimum. The solar EUV flux controls the ionization frequencies of the exospheric species, atomic hydrogen and oxygen, as well as the density, the temperature, and thus the extension of the exosphere. Ionization by photons and by electron impacts, and the main charge exchange reactions are self-consistently included in the simulation model. Simulation results are in reasonable agreement with the observations made by Phobos-2 and Mars Global Surveyor (MGS spacecraft: 1 the interaction creates a cavity, void of solar wind ions (H+, He++, which depends weakly upon the phase of the solar cycle, 2 the motional electric field of the solar wind flow creates strong asymmetries in the Martian environment, 3 the spatial distribution of the different components of the planetary plasma depends strongly upon the phase of the solar cycle. The fluxes of the escaping planetary ions are computed from the simulated data and results for solar maximum are compared with estimates based on the measurements made by experiments ASPERA and TAUS on board Phobos-2.

  20. Calibration of high-heat-flux sensors in a solar furnace

    Science.gov (United States)

    Ballestrín, J.; Rodríguez-Alonso, M.; Rodríguez, J.; Cañadas, I.; Barbero, F. J.; Langley, L. W.; Barnes, A.

    2006-12-01

    The most common sensors used for the measurement of high solar irradiance are the Gardon gauges, which are usually calibrated using a black body at a certain temperature as the radiant source. This calibration procedure is assumed to produce a systematic error when solar irradiance measurements are taken using these sensors. This paper demonstrates a calorimetric method for calibrating these high-heat-flux gauges in a solar furnace. This procedure has enabled these sensors to be calibrated under concentrated solar radiation at higher irradiances under non-laboratory conditions in the CIEMAT solar furnace at the Plataforma Solar de Almería. Working at higher irradiances has allowed the uncertainty in the calibration constant of these sensors to be reduced. This work experimentally confirms the predicted systematic errors committed when measuring high solar irradiances using Gardon sensors calibrated with a black body.

  1. Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes

    Science.gov (United States)

    Gómez-Herrero, Raúl; Dresing, Nina; Klassen, Andreas; Heber, Bernd; Temmer, Manuela; Veronig, Astrid; Bučík, Radoslav; Hidalgo, Miguel A.; Carcaboso, Fernando; Blanco, Juan J.; Lario, David

    2017-05-01

    On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation times are consistent with a low number of field line rotations N model used in this work suggests an even lower number of rotations.

  2. Data Mining Solar X-Ray Flares Triggered by Emerging Magnetic Flux

    Science.gov (United States)

    Loftus, Kaitlyn; Saar, Steven H.; Schanche, Nicole

    2017-01-01

    We investigate the association between emerging magnetic flux and solar X-ray flares to identify, and if possible quantify, distinguishing physical properties of flares triggered by flux emergence versus those triggered by other sources. Our study uses as its basis GOES-classified solar flares from March 2011 through June 2016 that have been identified by the Space Weather Prediction Center’s flare detection algorithm. The basic X-ray flare data is then enriched with data about related EUV-spectrum flares, emerging fluxes, active regions, eruptions, and sigmoids, which are all characterized by event-specific keywords, identified via SDO feature finding tools, and archived in the Heliophysics Events Knowledgebase (HEK). Using appropriate spatial and temporal parameters for each event type to determine association, we create a catalogue of solar events associated with each GOES-classified flare. After accounting for the primitive state of many of these event detection algorithms, we statistically analyze the compiled dataset to determine the effects of an emerging flux trigger on flare properties. A two-sample Kolmogorov-Smirnov test confirms with 99.9% confidence that flares triggered by emerging flux have a different peak flux distribution than non-emerging-flux-associated flares. We observe no linear or logarithmic correlations between flares’ and their associated emerging fluxes’ individual properties and find flares triggered by emerging flux are ~ 10% more likely to cause an eruption inside an active region while outside of an active region, the flare’s association with emerging flux has no effect on its likeliness to cause an eruption. We also compare the morphologies of the flares triggered by emerging flux and flares not via a superposed epoch analysis of lightcurves. Our results will be of interest for predicting flare behavior as a function of magnetic activity (where we can use enhanced rates of emerging flux as a proxy for heightened stellar

  3. HOMOLOGOUS FLUX ROPES OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY ATMOSPHERIC IMAGING ASSEMBLY

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting; Zhang, Jun, E-mail: liting@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-12-01

    We present the first Solar Dynamics Observatory observations of four homologous flux ropes in the active region (AR) 11745 on 2013 May 20-22. The four flux ropes are all above the neutral line of the AR, with endpoints anchoring at the same region, and have a generally similar morphology. The first three flux ropes rose with a velocity of less than 30 km s{sup –1} after their appearance, and subsequently their intensities at 131 Å decreased and the flux ropes became obscure. The fourth flux rope erupted last, with a speed of about 130 km s{sup –1} and formed a coronal mass ejection (CME). The associated filament showed an obvious anti-clockwise twist motion at the initial stage, and the twist was estimated at 4π. This indicates that kink instability possibly triggers the early rise of the fourth flux rope. The activated filament material was spatially within the flux rope and showed consistent evolution in the early stages. Our findings provide new clues for understanding the characteristics of flux ropes. Firstly, multiple flux ropes are successively formed at the same location during an AR evolution process. Secondly, a slow-rise flux rope does not necessarily result in a CME, and a fast-eruption flux rope does result in a CME.

  4. Net ecosystem exchange and energy fluxes measured with the eddy covariance technique in a western Siberian bog

    Directory of Open Access Journals (Sweden)

    P. Alekseychik

    2017-08-01

    Full Text Available Very few studies of ecosystem–atmosphere exchange involving eddy covariance data have been conducted in Siberia, with none in the western Siberian middle taiga. This work provides the first estimates of carbon dioxide (CO2 and energy budgets in a typical bog of the western Siberian middle taiga based on May–August measurements in 2015. The footprint of measured fluxes consisted of a homogeneous mixture of tree-covered ridges and hollows with the vegetation represented by typical sedges and shrubs. Generally, the surface exchange rates resembled those of pine-covered bogs elsewhere. The surface energy balance closure approached 100 %. Net CO2 uptake was comparatively high, summing up to 202 gC m−2 for the four measurement months, while the Bowen ratio was seasonally stable at 28 %. The ecosystem turned into a net CO2 source during several front passage events in June and July. The periods of heavy rain helped keep the water table at a sustainably high level, preventing a usual drawdown in summer. However, because of the cloudy and rainy weather, the observed fluxes might rather represent the special weather conditions of 2015 than their typical magnitudes.

  5. Forest cockchafer larvae as methane production hotspots in soils and their importance for net soil methane fluxes

    Science.gov (United States)

    Görres, Carolyn-Monika; Kammann, Claudia; Murphy, Paul; Müller, Christoph

    2016-04-01

    Certain groups of soil invertebrates, namely scarab beetles and millipedes, are capable of emitting considerable amounts of methane due to methanogens inhabiting their gut system. It was already pointed out in the early 1990's, that these groups of invertebrates may represent a globally important source of methane. However, apart from termites, the importance of invertebrates for the soil methane budget is still unknown. Here, we present preliminary results of a laboratory soil incubation experiment elucidating the influence of forest cockchafer larvae (Melolontha hippocastani FABRICIUS) on soil methane cycling. In January/February 2016, two soils from two different management systems - one from a pine forest (extensive use) and one from a vegetable field (intensive use) - were incubated for 56 days either with or without beetle larvae. Net soil methane fluxes and larvae methane emissions together with their stable carbon isotope signatures were quantified at regular intervals to estimate gross methane production and gross methane oxidation in the soils. The results of this experiment will contribute to testing the hypothesis of whether methane production hotspots can significantly enhance the methane oxidation capacity of soils. Forest cockchafer larvae are only found in well-aerated sandy soils where one would usually not suspect relevant gross methane production. Thus, besides quantifying their contribution to net soil methane fluxes, they are also ideal organisms to study the effect of methane production hotspots on overall soil methane cycling. Funding support: Reintegration grant of the German Academic Exchange Service (DAAD) (#57185798).

  6. Quasi-Static Evolution, Catastrophe, and Failed Eruption of Solar Flux Ropes

    Science.gov (United States)

    2016-12-30

    intrinsic flux rope properties such as the geometry and self magnetic field. The transition to eruption is catastrophic in that τR is finite. Numerical...AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: a. REPORT 19a. NAME OF RESPONSIBLE PERSON 19b...evolution of solar flux ropes subject to slowly increasing magnetic energy, encompassing quasi-static evolution, “catastrophic” transition to an eruptive

  7. The backward ray tracing with effective solar brightness used to simulate the concentrated flux map of a solar tower concentrator

    Science.gov (United States)

    Guo, Minghuan; Sun, Feihu; Wang, Zhifeng

    2017-06-01

    The solar tower concentrator is mainly composed of the central receiver on the tower top and the heliostat field around the tower. The optical efficiencies of a solar tower concentrator are important to the whole thermal performance of the solar tower collector, and the aperture plane of a cavity receiver or the (inner or external) absorbing surface of any central receiver is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated time-changing solar flux density distributions on the flat or curved receiving surface of the collector, with main optical errors considered. The transient concentrated solar flux on the receiving surface is the superimposition of the flux density distributions of all the normal working heliostats in the field. In this paper, we will mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the flux density map on the receiving-surface. For BRT, bundles of rays are launched at the receiving-surface points of interest, strike directly on the valid cell centers among the uniformly sampled mirror cell centers in the mirror surface of the heliostats, and then direct to the effective solar cone around the incident sun beam direction after reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is here supposed to be circular Gaussian type. The mirror curvature can be adequately formulated by certain number of local normal vectors at the mirror cell centers of a heliostat. The shading & blocking mirror region of a heliostat by neighbor heliostats and also the solar tower shading on the heliostat mirror are all computed on the flat-ground-plane platform, i.e., projecting the mirror contours and the envelope cylinder of the tower onto the horizontal ground plane along the sun-beam incident direction or along the reflection directions. If the shading projection of a sampled

  8. Solar Open Flux Migration from Pole to Pole: Magnetic Field Reversal

    OpenAIRE

    Huang, G.-H.; Lin, C.-H.; Lee, L. C.

    2017-01-01

    Coronal holes are solar regions with low soft X-ray or low extreme ultraviolet intensities. The magnetic fields from coronal holes extend far away from the Sun, and thus they are identified as regions with open magnetic field lines. Coronal holes are concentrated in the polar regions during the sunspot minimum phase, and spread to lower latitude during the rising phase of solar activity. In this work, we identify coronal holes with outward and inward open magnetic fluxes being in the opposite...

  9. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  10. Reanalysis of the GALLEX solar neutrino flux and source experiments

    Science.gov (United States)

    Kaether, F.; Hampel, W.; Heusser, G.; Kiko, J.; Kirsten, T.

    2010-02-01

    After the completion of the gallium solar neutrino experiments at the Laboratori Nazionali del Gran Sasso (GALLEX: 1991-1997; GNO: 1998-2003) we have retrospectively updated the GALLEX results with the help of new technical data that were impossible to acquire for principle reasons before the completion of the low rate measurement phase (that is, before the end of the GNO solar runs). Subsequent high rate experiments have allowed the calibration of absolute internal counter efficiencies and of an advanced pulse shape analysis for counter background discrimination. The updated overall result for GALLEX (only) is 73.4-7.3+7.1 SNU. This is 5.3% below the old value of 77.5-7.8+7.5 SNU (GALLEX Collaboration, W. Hampel et al., 1999 [1]), with a substantially reduced error. A similar reduction is obtained from the reanalysis of the 51Cr neutrino source experiments of 1994/1995.

  11. Statistical partitioning of a three-year time series of direct urban net CO2 flux measurements into biogenic and anthropogenic components

    Science.gov (United States)

    Menzer, Olaf; McFadden, Joseph P.

    2017-12-01

    Eddy covariance flux measurements are increasingly used to quantify the net carbon dioxide exchange (FC) in urban areas. FC represents the sum of anthropogenic emissions, biogenic carbon release from plant and soil respiration, and carbon uptake by plant photosynthesis. When FC is measured in natural ecosystems, partitioning into respiration and photosynthesis is a well-established procedure. In contrast, few studies have partitioned FC at urban flux tower sites due to the difficulty of accounting for the temporal and spatial variability of the multiple sources and sinks. Here, we partitioned a three-year time series of flux measurements from a suburban neighborhood of Minneapolis-Saint Paul, Minnesota, USA. We segregated FC into one subset that captured fluxes from a residential neighborhood and into another subset that covered a golf course. For both land use types we modeled anthropogenic flux components based on winter data and extrapolated them to the growing season, to estimate gross primary production (GPP) and ecosystem respiration (Reco) at half-hourly, daily, monthly and annual scales. During the growing season, GPP had the largest magnitude (up to - 9.83 g C m-2 d-1) of any component CO2 flux, biogenic or anthropogenic, and both GPP and Reco were more dynamic seasonally than anthropogenic fluxes. Owing to the balancing of Reco against GPP, and the limitations of the growing season in a cold temperate climate zone, the net biogenic flux was only 1.5%-4.5% of the anthropogenic flux in the dominant residential land use type, and between 25%-31% of the anthropogenic flux in highly managed greenspace. Still, the vegetation sink at our site was stronger than net anthropogenic emissions on 16-20 days over the residential area and on 66-91 days over the recreational area. The reported carbon flux sums and dynamics are a critical step toward developing models of urban CO2 fluxes within and across cities that differ in vegetation cover.

  12. Engineering and erection of a 300kW high-flux solar simulator

    Science.gov (United States)

    Wieghardt, Kai; Laaber, Dmitrij; Hilger, Patrick; Dohmen, Volkmar; Funken, Karl-Heinz; Hoffschmidt, Bernhard

    2017-06-01

    German Aerospace Center (DLR) is currently constructing a new high-flux solar simulator synlight which shall be commissioned in late 2016. The new facility will provide three separately operated experimental spaces with expected radiant powers of about 300kW / 240kW / 240kW respectively. synlight was presented to the public for the first time at SolarPACES 2015 [1]. Its engineering and erection is running according to plan. The current presentation reports about the engineering and the ongoing erection of the novel facility, and gives an outlook on its new level of possibilities for solar testing and qualification.

  13. LONG-TERM (SOLAR CYCLE) VARIATION OF THE EXTREME ULTRAVIOLET RADIATION AND 10.7CENTIMETER FLUX FROM THE SUN.

    Science.gov (United States)

    The proposal is made that the 10.7-cm flux from the sun , generally regarded as a good index of the solar extreme ultraviolet radiation (EUV), does...in some degree, since many features of the sun vary with the solar cycle. With regard to the radio waves represented by the flux and optical

  14. Interannual variability of net ecosystem productivity in forests is explained by carbon flux phenology in autumn

    DEFF Research Database (Denmark)

    Wu, Chaoyang; Chen, Xi Jing; Black, T. Andrew

    2013-01-01

    ) and 13 evergreen needleleaf forests (ENF) across North America and Europe (212 site‐years) were used to explore the relationships between the yearly anomalies of annual NEP and several carbon flux based phenological indicators, including the onset/end of the growing season, onset/end of the carbon uptake...... period, the spring lag (time interval between the onset of growing season and carbon uptake period) and the autumn lag (time interval between the end of the carbon uptake period and the growing season). Meteorological variables, including global shortwave radiation, air temperature, soil temperature...

  15. A figure of merit to evaluate transparent conductor oxides for solar cells using photonic flux density

    Energy Technology Data Exchange (ETDEWEB)

    Mendez-Gamboa, J.A., E-mail: jmendez@uady.mx [Engineering School, University of Yucatan, AP 150 Cordemex, 97310 Mérida, Yucatán (Mexico); Castro-Rodriguez, R. [Applied Physics Department, CINVESTAV-IPN Mérida, C.P. 97310, Mérida, Yucatán (Mexico); Perez-Quintana, I.V.; Medina-Esquivel, R.A.; Martel-Arbelo, A. [Engineering School, University of Yucatan, AP 150 Cordemex, 97310 Mérida, Yucatán (Mexico)

    2016-01-29

    We report an alternative method to evaluate transparent conductor oxides (TCO) from their photonic flux density (PFD(hυ)) to be used in solar cells. From the transmittance spectrum (T(hυ)) in the visible region, we calculate the PFD(hυ) and the solar photon flux-weighted transmittance (T{sub SW}) of one specific TCO with potential application in solar cells. The photo-current density (J{sub PH}) in mA/cm{sup 2} of one specific TCO when exposed to white light is evaluated when PFD(hυ) is integrated over the whole solar electromagnetic spectrum. Finally, we define a figure of merit as J{sub PH} over the TCO film sheet resistance to find the best equilibrium between the transmission and its electrical resistance. To carry out this work, a bibliographical search of investigations about development of TCOs was extensively made to evaluate its T(hυ), T{sub SW,} PFD(hυ), J{sub PH} and the figure of merit that we propose. From our results, we consider that the proposed method is a good tool for a fine comparison of transparent conductive films in solar cell development. - Highlights: • A figure of merit is presented for the evaluation of TCO used in solar cells. • It is defined as the ratio of photo-current density over TCO sheet resistance. • It is a tool for a fine comparison of TCO films in solar cell development.

  16. Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

    Directory of Open Access Journals (Sweden)

    Barthelemy Mathieu

    2014-01-01

    Full Text Available The solar UV (UltraViolet flux, especially the EUV (Extreme UltraViolet and FUV (Far UltraViolet components, is one of the main energetic inputs for planetary upper atmospheres. It drives various processes such as ionization, or dissociation which give rise to upper atmospheric emissions, especially in the UV and visible. These emissions are one of the main ways to investigate the upper atmospheres of planets. However, the uncertainties in the flux measurement or modeling can lead to biased estimates of fundamental atmospheric parameters, such as concentrations or temperatures in the atmospheres. We explore the various problems that can be identified regarding the uncertainties in solar/stellar UV flux by considering three examples. The worst case appears when the solar reflection component is dominant in the recorded spectrum as is seen for outer solar system measurements from HST (Hubble Space Telescope. We also show that the estimation of some particular line parameters (intensity and shape, especially Lyman α, is crucial, and that both total intensity and line profile are useful. In the case of exoplanets, the problem is quite critical since the UV flux of their parent stars is often very poorly known.

  17. Large-scale Flow and Transport of Magnetic Flux in the Solar ...

    Indian Academy of Sciences (India)

    tribpo

    Abstract. Horizontal large-scale velocity field describes horizontal displacement of the photospheric magnetic flux in zonal and meridian directions. The flow systems of solar plasma, constructed according to the velocity field, create the large-scale cellular-like patterns with up-flow in the center and the down-flow on the ...

  18. Effect of Step-Change Radiation Flux on Dynamic Characteristics in Tower Solar Cavity Receiver

    Directory of Open Access Journals (Sweden)

    Zhengwei Chen

    2013-01-01

    Full Text Available The heat flux on the inner surface of the tower solar thermal power plant system will show the characteristics of noncontinuous step change, especially in nonnormal and transient weather conditions, which may result in a continuous dynamic variation of the characteristic parameters. Therefore, the research of dynamic characteristics plays a very important role in the operation and the control safely in solar cavity receiver system. In this paper, based on the noncontinuous step change of radiation flux, a non-linear dynamic model is constructed to obtain the effects of the non-continuous step change radiation flux and step change feed water flow on the receiver performance by sequential modular approach. The subject investigated in our study is a 1 MW solar power station constructed in Yanqing county, Beijing, China. This study has obtained the dynamic responses of the characteristic parameters in the cavity receiver such as drum pressure, drum water level, main steam flow, and main steam enthalpy under step change radiation flux. And the influence of step-change feed water flow to the dynamic characteristics has also been analyzed. The results could provide general guidance for security operation and control in solar cavity receiver system.

  19. Zonal winds in the equatorial upper thermosphere : Decomposing the solar flux, geomagnetic activity, and seasonal dependencies

    NARCIS (Netherlands)

    Liu, H.; Lühr, H.; Watanabe, S.; Köhler, W.; Henize, V.; Visser, P.N.A.M.

    2006-01-01

    Using 3 years (2002–2004), over 16,400 orbits of measurements from the accelerometer on board the CHAMP satellite, we have studied the climatology of the equatorial zonal wind in the upper thermosphere. Several main features are noticed. The most prominent one is that the solar flux significantly

  20. Changed Relation between Solar 10.7-cm Radio Flux and some ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 35; Issue 1. Changed Relation between Solar 10.7-cm Radio Flux and some Activity Indices which describe the Radiation at Different Altitudes of Atmosphere during Cycles 21–23. E. A. Bruevich V. V. Bruevich G. V. Yakunina. General ...

  1. Study and Simulation of the Density of the Incident Solar Flux on the Walls of a Building in Adrar, Algeria

    Directory of Open Access Journals (Sweden)

    A. Oudrane

    2017-10-01

    Full Text Available In this work, we studied the effect of external climatic conditions on the evolution of the daily solar flux incident on the walls of a building located at Adrar region in the South of Algeria. This building is designed for heating or air conditioning applications. Numerical simulations allowed to compare the variation of the incident solar flux over a full day on the south, east, north and west walls of the building to the values of the solar flux on a horizontal wall (the outer ceiling. The horizontal global solar flux is calculated using a Gaussian sinusoidal function. The simulations were carried out in the case of a building located in a desert zone. The results of the numerical simulation showed the effect of the orientation of the building on the evolution of the incident daily solar flux.

  2. Martian ionosphere observed by Mars Express. 2. Influence of solar irradiance on upper ionosphere and escape fluxes

    Science.gov (United States)

    Dubinin, E.; Fraenz, M.; Pätzold, M.; Andrews, D.; Vaisberg, O.; Zelenyi, L.; Barabash, S.

    2017-10-01

    We present multi-instrument observations of the effects of solar irradiance on the upper Martian ionosphere and escape fluxes based on Mars Express measurements obtained over almost 12 years. It is shown that the variations in the upper ionosphere caused by solar irradiance lead to significant changes in the trans-terminator fluxes of low-energy ions and total ion losses through the tail. The observed dependence of the electron number density in the upper ionosphere at altitudes above 300 km on solar irradiance implies that the ionosphere at such altitudes was denser by a factor of ten during the periods of solar maxima in solar cycles 22-23. Correspondingly, the trans-terminator fluxes of cold ions and escape fluxes through the tail were also significantly higher. We estimate an increase of total ion losses through the tail during these solar maxima by a factor of 5-6.

  3. The Net Carbon Flux due to Deforestation and Forest Re-Growth in the Brazilian Amazon: Analysis using a Process-Based Model

    Science.gov (United States)

    Hirsch, A. I.; Little, W. S.; Houghton, R. A.; Scott, N. A.; White, J. D.

    2004-01-01

    We developed a process-based model of forest growth, carbon cycling, and land cover dynamics named CARLUC (for CARbon and Land Use Change) to estimate the size of terrestrial carbon pools in terra firme (non-flooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study of the impact of Amazonian deforestation, selective logging, and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re-growth over the period from 1970-1998. We calculate that the net flux to the atmosphere during this period reached a maximum of approx. 0.35 PgC/yr (1PgC = 1 x 10(exp I5) gC) in 1990, with a cumulative release of approx. 7 PgC from 1970- 1998. The net flux is higher than predicted by an earlier study by a total of 1 PgC over the period 1989-1 998 mainly because CARLUC predicts relatively high mature forest carbon storage compared to the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by approx. 1 PgC from 1970-1998, while different assumptions about land cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte-Carlo approach, is roughly 35% of the mean value (1 SD).

  4. GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC FLUX TUBES BY PHOTOSPHERIC MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mumford, S. J.; Fedun, V.; Erdélyi, R., E-mail: s.mumford@sheffield.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH UK (United Kingdom)

    2015-01-20

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

  5. Preliminary Design of a Solar Photovoltaic Array for Net-Zero Energy Buildings at NASA Langley

    Science.gov (United States)

    Cole, Stuart K.; DeYoung, Russell J.

    2012-01-01

    An investigation was conducted to evaluate photovoltaic (solar electric systems) systems for a single building at NASA Langley as a representative case for alternative sustainable power generation. Building 1250 in the Science Directorate is comprised of office and laboratory space, and currently uses approximately 250,000 kW/month of electrical power with a projected use of 200,000 kW/month with additional conservation measures. The installation would be applied towards a goal for having Building 1250 classified as a net-zero energy building as it would produce as much energy as it uses over the course of a year. Based on the facility s electrical demand, a photovoltaic system and associated hardware were characterized to determine the optimal system, and understand the possible impacts from its deployment. The findings of this investigation reveal that the 1.9 MW photovoltaic electrical system provides favorable and robust results. The solar electric system should supply the needed sustainable power solution especially if operation and maintenance of the system will be considered a significant component of the system deployment.

  6. Net radiation, sensible and latent heat flux densities on slopes computed by the energy balance method

    Science.gov (United States)

    Fritschen, Leo; Qian, Ping

    1990-01-01

    Energy balance components obtained over five grass-covered sloping surfaces near Manhattan, KS, using the Bowen ratio energy balance technique with the instruments mounted horizontally were compared with calculated values when the instruments were mounted parallel to the surfaces. Hourly values of the components changed when the instruments were parallel to the surfaces. The changes were larger at low solar angles (spring and fall) and on steeper slopes. An area average of daylight totals, assuming that all aspects were equally represented, changed only 0.1 percent on June 6 and 2.3 percent on October 11. The calculations, extended to steeper slopes, indicated small changes in the daylight totals for slopes of less than 10 deg.

  7. Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

    Science.gov (United States)

    Martin, Patrick; van der Loeff, Michiel Rutgers; Cassar, Nicolas; Vandromme, Pieter; d'Ovidio, Francesco; Stemmann, Lars; Rengarajan, R.; Soares, Melena; González, Humberto E.; Ebersbach, Friederike; Lampitt, Richard S.; Sanders, Richard; Barnett, Bruce A.; Smetacek, Victor; Naqvi, S. Wajih A.

    2013-09-01

    closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled after fertilization, and photosynthetic quantum yield (FV/FM) increased from 0.33 to ≥0.40. Silicic acid (artificially fertilized bloom with very low diatom biomass. Net community production (NCP) inside the patch, estimated from O2:Ar ratios, averaged 21 mmol POC m-2 d-1, probably ±20%. 234Th profiles implied constant export of 6.3 mmol POC m-2 d-1 in the patch, similar to unfertilized waters. The difference between NCP and 234Th-derived export partly accumulated in the mixed layer and was partly remineralized between the mixed layer and 100 m. Neutrally buoyant sediment traps at 200 and 450 m inside and outside the patch caught mostly fertilization. Our data thus indicate intense flux attenuation between 100 and 200 m, and probably between the mixed layer and 100 m. We attribute the lack of fertilization-induced export to silicon limitation of diatoms and reprocessing of sinking particles by detritus feeders. Our data are consistent with the view that nitrate-rich but silicate-deficient waters are not poised for enhanced particle export upon iron addition.

  8. Plasma β Scaling of Anisotropic Magnetic Field Fluctuations in the Solar Wind Flux Tube

    Science.gov (United States)

    Sarkar, Aveek; Bhattacharjee, Amitava; Ebrahimi, Fatima

    2014-03-01

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of "spaghetti"-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma β dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma β. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  9. Plasma β scaling of anisotropic magnetic field fluctuations in the solar wind flux tube

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Aveek [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Bhattacharjee, Amitava; Ebrahimi, Fatima, E-mail: aveek.sarkar@unh.edu, E-mail: amitava@princeton.edu, E-mail: ebrahimi@princeton.edu [Department of Astrophysical Sciences and Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States)

    2014-03-10

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of 'spaghetti'-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma β dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma β. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  10. Heat flux: thermohydraulic investigation of solar air heaters used in agro-industrial applications

    Science.gov (United States)

    Rahmati Aidinlou, H.; Nikbakht, A. M.

    2017-03-01

    A new design of solar air heater simulator is presented to comply with the extensive applications inagro-industry. A wise installation of increased heat transfer surface area provided uniform and efficient heat diffusion over the duct. Nusselt number and friction factor have been investigated based on the constant roughness parameters such as relative roughness height (e/D), relative roughness pitch (P/e), angle of attack (α) and aspect ratio with Reynolds numbers ranging from 5000 to 19,000 in the fully developed region. Heat fluxes of 800, 900 and 1000 Wm-2 were provided. The enhancement in friction factor is observed to be 3.1656, 3.47 and 3.0856 times, and for the Nusselt number either, augmentation is calculated to be 1.4437, 1.4963 and 1.535 times, respectively, over the smooth duct for 800, 900 and 1000 Wm-2 heat fluxes. Thermohydraulic performance is plotted versus the Reynolds number based on the aforementioned roughness parameters at varying heat fluxes. The results show up that thermohydraulic performance is found to be maximum for 1000 Wm-2 at the average Reynolds number of 5151. Based on the results, we can verify that the introduced solar simulator can help analyzing and developing solar collector installations at the simulated heat fluxes.

  11. Flux-transport and mean-field dynamo theories of solar cycles

    Science.gov (United States)

    Choudhuri, Arnab Rai

    2013-07-01

    We point out the difficulties in carrying out direct numerical simulation of the solar dynamo problem and argue that kinematic mean-field models are our best theoretical tools at present for explaining various aspects of the solar cycle in detail. The most promising kinematic mean-field model is the flux transport dynamo model, in which the toroidal field is produced by differential rotation in the tachocline, the poloidal field is produced by the Babcock-Leighton mechanism at the solar surface and the meridional circulation plays a crucial role. Depending on whether the diffusivity is high or low, either the diffusivity or the meridional circulation provides the main transport mechanism for the poloidal field to reach the bottom of the convection zone from the top. We point out that the high-diffusivity flux transport dynamo model is consistent with various aspects of observational data. The irregularities of the solar cycle are primarily produced by fluctuations in the Babcock-Leighton mechanism and in the meridional circulation. We summarize recent work on the fluctuations of meridional circulation in the flux transport dynamo, leading to explanations of such things as the Waldmeier effect.

  12. Interplanetary Magnetic Flux Ropes as Agents Connecting Solar Eruptions and Geomagnetic Activities

    Science.gov (United States)

    Marubashi, K.; Cho, K.-S.; Ishibashi, H.

    2017-12-01

    We investigate the solar wind structure for 11 cases that were selected for the campaign study promoted by the International Study of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group 4. We can identify clear flux rope signatures in nine cases. The geometries of the nine interplanetary magnetic flux ropes (IFRs) are examined with a model-fitting analysis with cylindrical and toroidal force-free flux rope models. For seven cases in which magnetic fields in the solar source regions were observed, we compare the IFR geometries with magnetic structures in their solar source regions. As a result, we can confirm the coincidence between the IFR orientation and the orientation of the magnetic polarity inversion line (PIL) for six cases, as well as the so-called helicity rule as regards the handedness of the magnetic chirality of the IFR, depending on which hemisphere of the Sun the IFR originated from, the northern or southern hemisphere; namely, the IFR has right-handed (left-handed) magnetic chirality when it is formed in the southern (northern) hemisphere of the Sun. The relationship between the orientation of IFRs and PILs can be taken as evidence that the flux rope structure created in the corona is in most cases carried through interplanetary space with its orientation maintained. In order to predict magnetic field variations on Earth from observations of solar eruptions, further studies are needed about the propagation of IFRs because magnetic fields observed at Earth significantly change depending on which part of the IFR hits the Earth.

  13. The empirical and semiempirical methodology in the cosmic ray and solar energetic particle flux model development

    Science.gov (United States)

    Nymmik, R. A.

    Due to the complexity of processes, causing the occurrence of cosmic ray and solar energetic particle fluxes in space, the available physical models are hardly capable of giving a complete description of the fluxes and their dynamics. In order to describe the particle fluxes numerically, empirical and semi-empirical models are developed. Empirical models restrict themselves to a quantitative description of the final effect - particle fluxes and their dynamics or variations in the form of simple approximations, represented as tables or figures. When developing semi-empirical models, descriptions of intermediate regularities are used. The set of such intermediate regularities, comprising a logic series leads to the final effect. Such models are capable of describing not only the final effect, but also the intermediate phenomena, refinement of which permit to increase the reliability of the model in general. As an example of an empirical model we can indicate CRÈME-81, where particle flux variations during the solar cycle were described by means of a sinusoidal function. Later, a semi-empirical model was developed at Moscow State University. This model used Wolf numbers as the initial parameter, and accounted for effects, caused by the 22-year dynamics of the large-scale magnetic field. One of the versions of this model was used in CRÈME-96 and adopted as an International Standard (ISO 15390). A similar situation currently exists for SEP particle fluxes. Along with such empirical models as JPL-91 and Xapsos et al. (a number of publications), a semi-empirical model has been developed at MSU. This model has been submitted for discussion as the draft of an international standard. Whilst empirical models describe proton fluxes for some abstract active Sun period and for proton fluxes of certain fixed energies, a semi-empirical model describes particle fluxes for any solar activity level, providing the output data in analytical form and giving the user with additional

  14. Nonlinearity measurements of solar cells with an LED-based combinatorial flux addition method.

    Science.gov (United States)

    Hamadani, Behrang H; Shore, Andrew; Roller, John; Yoon, Howard W; Campanelli, Mark

    2016-02-01

    We present a light emitting diode (LED)-based system utilizing a combinatorial flux addition method to investigate the nonlinear relationship in solar cells between the output current of the cell and the incident irradiance level. The magnitude of the light flux is controlled by the supplied currents to two LEDs (or two sets of them) in a combinatorial fashion. The signals measured from the cell are arranged within a related overdetermined linear system of equations derived from an appropriately chosen Nth degree polynomial representing the relationship between the measured signals and the incident fluxes. The flux values and the polynomial coefficients are then solved for by linear least squares to obtain the best fit. The technique can be applied to any solar cell, under either monochromatic or broadband spectrum. For the unscaled solution, no reference detectors or prior calibrations of the light flux are required. However, if at least one calibrated irradiance value is known, then the entire curve can be scaled to an appropriate spectral responsivity value. Using this technique, a large number of data points can be obtained in a relatively short time scale over a large signal range.

  15. Process for reducing series resistance of solar cell metal contact systems with a soldering flux etchant

    Science.gov (United States)

    Coyle, R. T.; Barrett, Joy M.

    1984-01-01

    Disclosed is a process for substantially reducing the series resistance of a solar cell having a thick film metal contact assembly thereon while simultaneously removing oxide coatings from the surface of the assembly prior to applying solder therewith. The process includes applying a flux to the contact assembly and heating the cell for a period of time sufficient to substantially remove the series resistance associated with the assembly by etching the assembly with the flux while simultaneously removing metal oxides from said surface of said assembly.

  16. INVESTIGATION OF SOLAR ABSORPTANCE OF BUILDING EXTERNAL SURFACES FROM HEAT FLUX POINT OF VIEW

    Directory of Open Access Journals (Sweden)

    Meral ÖZEL

    2006-02-01

    Full Text Available In this study, solar absorptance of external surfaces of buildings has been numerically investigated from the heat gain and losses point of view. For this purpose, external surface solar absorptance was icreased from 0 to 1with an ratio of 0.1 and, for the summer and winter conditions, heat fluxs was calculated by considering orientations of the wall and its roof for brick and concrete structure materials. Besides, external surface absorptance was assumed as 0.2, 0.5 and 0.9, respectively. Than, heat gain and losses were calculated to insulation thickness increasing on the outdoor surface of wall. Results obtained were presented as graphics

  17. Determining the Flavour Content of the Low-Energy Solar Neutrino Flux

    CERN Document Server

    De Gouvêa, A; Gouvea, Andre de; Murayama, Hitoshi

    2000-01-01

    We study the sensitivity of the HELLAZ and Borexino solar neutrino experiments on discriminating the neutrino species nu_e, anti-nu_e, nu_{mu,tau}, anti-nu_{mu,tau}, and nu_{sterile} using the difference in the recoil electron kinetic energy spectra in elastic neutrino-electron scattering. We find that one can observe a non-vanishing nu_{mu,tau} component in the solar neutrino flux, especially when the nu_e survival probability is low. Also, if the data turn out to be consistent with nu_e nu_{mu,tau} oscillations, an anti-nu_e component can be excluded effectively.

  18. High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

    Science.gov (United States)

    Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.

    1997-01-01

    As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near

  19. Effect of resistant starch on net portal-drained viscera flux of glucose, volatile fatty acids, urea, and ammonia in growing pigs

    NARCIS (Netherlands)

    Meulen, van der J.; Bakker, G.C.M.; Bakker, J.G.M.; Visser, de H.; Jongbloed, A.W.; Everts, H.

    1997-01-01

    Net portal-drained viscera (PDV) flux of glucose, VFA, ammonia, and urea was determined in pigs fed diets with or without resistant starch. Diets consisted of 65% cornstarch (diet CS), 32.5% cornstarch and 32.5% raw potato starch (diet CPS), or 65% raw potato starch (diet PS); the remaining 35%

  20. Measurement of the 8B Solar Neutrino Flux with KamLAND

    Energy Technology Data Exchange (ETDEWEB)

    Abe, S.; Furuno, K.; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K.; Kibe, Y.; Kimura, W.; Kishimoto, Y.; Koga, M.; Minekawa, Y.; Mitsui, T.; Morikawa, T.; Nagai, N.; Nakajima, K.; Nakamura, K.; Nakamura, M.; Narita, K.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F.; Suzuki, A.; Takahashi, H.; Takahashi, N.; Takemoto, Y.; Tamae, K.; Watanabe, H.; Xu, B.D.; Yabumoto, H.; Yonezawa, E.; Yoshida, H.; Yoshida, S.; Enomoto, S.; Kozlov, A.; Murayama, H.; Grant, C.; Keefer, G.; McKee, D.; Piepke, A.; Banks, T.I.; Bloxham, T.; Detwiler, J.A.; Freedman, S.J.; Fujikawa, B.K.; Han, K.; Kadel, R.; O' Donnell, T.; Steiner, H.M.; Winslow, L.A.; Dwyer, D.A.; Mauger, C.; McKeown, R.D.; Zhang, C.; Berger, B.E.; Lane, C.E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J.G.; Matsuno, S.; Pakvasa, S.; Sakai, M.; Horton-Smith, G.A.; Tang, A.; Downum, K.E.; Gratta, G.; Tolich, K.; Efremenko, Y.; Kamyshkov, Y.; Perevozchikov, O.; Karwowski, H.J.; Markoff, D.M.; Tornow, W.; Heeger, K.M.; Piquemal, F.; Ricol, J.-S.; Decowski, M.P.

    2011-06-04

    We report a measurement of the neutrino-electron elastic scattering rate from {sup 8}B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 {+-} 0.14(stat) {+-} 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a {sup 8}B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 {+-} 0.26(stat) {+-} 0.32(syst) x 10{sup 6} cm{sup -2}s{sup -1}. The analysis threshold is driven by {sup 208}Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic {sup 11}Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.

  1. Measurement of the 8B Solar Neutrino Flux with KamLAND

    CERN Document Server

    Abe, S; Gando, A; Gando, Y; Ichimura, K; Ikeda, H; Inoue, K; Kibe, Y; Kimura, W; Kishimoto, Y; Koga, M; Minekawa, Y; Mitsui, T; Morikawa, T; Nagai, N; Nakajima, K; Nakamura, K; Nakamura, M; Narita, K; Shimizu, I; Shimizu, Y; Shirai, J; Suekane, F; Suzuki, A; Takahashi, H; Takahashi, N; Takemoto, Y; Tamae, K; Watanabe, H; Xu, B D; Yabumoto, H; Yonezawa, E; Yoshida, H; Yoshida, S; Enomoto, S; Kozlov, A; Murayama, H; Grant, C; Keefer, G; McKee, D; Piepke, A; Banks, T I; Bloxham, T; Detwiler, J A; Freedman, S J; Fujikawa, B K; Han, K; Kadel, R; O'Donnell, T; Steiner, H M; Winslow, L A; Dwyer, D A; Mauger, C; McKeown, R D; Zhang, C; Berger, B E; Lane, C E; Maricic, J; Miletic, T; Batygov, M; Learned, J G; Matsuno, S; Pakvasa, S; Sakai, M; Horton-Smith, G A; Tang, A; Downum, K E; Gratta, G; Tolich, K; Efremenko, Y; Kamyshkov, Y; Perevozchikov, O; Karwowski, H J; Markoff, D M; Tornow, W; Heeger, K M; Piquemal, F; Ricol, J -S; Decowski, M P

    2011-01-01

    We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.

  2. On the Relationship Between High Speed Solar Wind Streams and Radiation Belt Electron Fluxes

    Science.gov (United States)

    Zheng, Yihua

    2011-01-01

    Both past and recent research results indicate that solar wind speed has a close connection to radiation belt electron fluxes [e.g., Paulikas and Blake, 1979; Reeves et aI., 2011]: a higher solar wind speed is often associated with a higher level of radiation electron fluxes. But the relationship can be very complex [Reeves et aI., 2011]. The study presented here provides further corroboration of this viewpoint by emphasizing the importance of a global perspective and time history. We find that all the events during years 2010 and 2011 where the >0.8 MeV integral electron flux exceeds 10(exp 5) particles/sq cm/sr/s (pfu) at GEO orbit are associated with the high speed streams (HSS) following the onset of the Stream Interaction Region (SIR), with most of them belonging to the long-lasting Corotating Interaction Region (CIR). Our preliminary results indicate that during HSS events, a maximum speed of 700 km/s and above is a sufficient but not necessary condition for the > 0.8 MeV electron flux to reach 10(exp 5) pfu. But in the exception cases of HSS events where the electron flux level exceeds the 10(exp 5) pfu value but the maximum solar wind speed is less than 700 km/s, a prior impact can be noted either from a CME or a transient SIR within 3-4 days before the arrival of the HSS - stressing the importance of time history. Through superposed epoch analysis and studies providing comparisons with the CME events and the HSS events where the flux level fails to reach the 10(exp 5) pfu, we will present the quantitative assessment of behaviors and relationships of various quantities, such as the time it takes to reach the flux threshold value from the stream interface and its dependence on different physical parameters (e.g., duration of the HSS event, its maximum or average of the solar wind speed, IMF Bz, Kp). The ultimate goal is to apply what is derived to space weather forecasting.

  3. Biogenic carbon fluxes from global agricultural production and consumption: Gridded, annual estimates of net ecosystem carbon exchange

    Science.gov (United States)

    Wolf, J.; West, T. O.; le Page, Y.; Thomson, A. M.

    2014-12-01

    Quantification of biogenic carbon fluxes from agricultural lands is needed to generate globally consistent bottom-up estimates for carbon monitoring and model input. We quantify agricultural carbon fluxes associated with annual (starting in 1961) crop net primary productivity (NPP), harvested biomass, and human and livestock consumption and emissions, with estimates of uncertainty, by applying region- and species-specific carbon parameters to annual crop, livestock, food and trade inventory data, and generate downscaled, gridded (0.05 degree resolution) representations of these fluxes. In 2011, global crop NPP was 5.25 ± 0.46 Pg carbon (excluding root exudates), of which 2.05 ± 0.051 Pg carbon was harvested as primary crops; an additional 0.54 Pg of crop residue carbon was collected for livestock fodder. In 2011, total livestock feed intake was 2.42 ± 0.21 Pg carbon, of which 2.31 ± 0.21 Pg carbon was emitted as carbon dioxide and 0.072 ± 0.005 Pg carbon was emitted as methane. We estimate that livestock grazed 1.18 Pg carbon from non-crop lands in 2011, representing 48.5 % of global total feed intake. In 2009, the latest available data year, we estimate global human food intake (excluding seafood and orchard fruits and nuts) at 0.52 ± 0.03 Pg carbon, with an additional 0.24 ± 0.01 Pg carbon of food supply chain losses. Trends in production and consumption of agricultural carbon between 1961 and recent years, such as increasing dominance of oilcrops and decreasing percent contribution of pasturage to total livestock feed intake, are discussed, and accounting of all agricultural carbon was done for the years 2005 and 2009. Gridded at 0.05 degree resolution, these quantities represent local uptake and release of agricultural biogenic carbon (e.g. biomass production and removal, residue and manure inputs to soils) and may be used with other gridded data to help estimate current and future changes in soil organic carbon.

  4. Flux-Tube Texture of the Solar Wind: Weakly Compressible MHD Theory and Direct Numerical Simulations

    Science.gov (United States)

    Bhattacharjee, A.; Sarkar, A.; Ebrahimi, F.

    2012-10-01

    Over the years, there has been a steady accumulation of observational evidence that the solar wind may be thought of as a network of individual magnetic flux tubes each with its own magnetic and plasma characteristics [Bartley et al. 1966, Marliani et al. 1973, Tu and Marsch 1990, Bruno et al. 2001, Borovsky 2008]. The weakly compressible MHD (WC-MHD) model [Bhattacharjee et al., 1998], which incorporates the effect of background spatial inhomogeneities, has been used recently to characterize the anisotropic magnetic fluctuation spectra (the so-called variance anisotropy) observed by ACE spacecraft. For a model of local pressure-driven interchange turbulence in a generic solar wind flux tube, the WC-MHD theory uses the Invariance Principle approach [Connor and Taylor 1997, Bhattacharjee and Hameiri 1988] to calculate explicitly the scaling of magnetic field fluctuations with plasma beta and other background plasma parameters. We test these theoretical predictions by direct numerical simulations of interchange turbulence in a flux tube using the DEBS MHD code. Synthetic variance anisotropy within a generic flux tube is computed in the high-Lundquist-number regime, and shows remarkable similarity with ACE observations.

  5. Equilibrium force balance and eruptive instabilities in solar-relevant laboratory magnetic flux ropes

    Science.gov (United States)

    Myers, C. E.; Yamada, M.; Belova, E. V.; Ji, H.; Yoo, J.; Jara-Almonte, J.

    2013-10-01

    Quasi-statically driven line-tied magnetic flux ropes are studied in the context of storage-and-release eruptions in the solar corona. The Magnetic Reconnection Experiment (MRX) facility is utilized to produce these arched low- β flux ropes. Detailed in situ magnetic measurements and supporting MHD simulations permit quantitative analysis of the plasma behavior. We find that the orientation of the applied potential magnetic field arcade with respect to the flux rope footpoints (i.e., the electrodes) is key. With an arcade that is aligned parallel to the footpoints, force free currents induced in the expanding flux rope modify the pressure and tension in the arcade to produce a confined, quiescent discharge and a saturated kink instability. In an obliquely aligned arcade, on the other hand, a sigmoidal equilibrium forms that can dynamically erupt. Both the kink instability and the torus instability are studied as candidate eruptive mechanisms--the latter by varying the vertical gradient of the potential field arcade. New 2D magnetic measurements of these equilibrium and eruptive features facilitate comparisons to solar observations and modeling. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the Center for Magnetic Self-Organization (CMSO).

  6. A Comparison of Three Gap Filling Techniques for Eddy Covariance Net Carbon Fluxes in Short Vegetation Ecosystems

    Directory of Open Access Journals (Sweden)

    Xiaosong Zhao

    2015-01-01

    Full Text Available Missing data is an inevitable problem when measuring CO2, water, and energy fluxes between biosphere and atmosphere by eddy covariance systems. To find the optimum gap-filling method for short vegetations, we review three-methods mean diurnal variation (MDV, look-up tables (LUT, and nonlinear regression (NLR for estimating missing values of net ecosystem CO2 exchange (NEE in eddy covariance time series and evaluate their performance for different artificial gap scenarios based on benchmark datasets from marsh and cropland sites in China. The cumulative errors for three methods have no consistent bias trends, which ranged between −30 and +30 mgCO2 m−2 from May to October at three sites. To reduce sum bias in maximum, combined gap-filling methods were selected for short vegetation. The NLR or LUT method was selected after plant rapidly increasing in spring and before the end of plant growing, and MDV method was used to the other stage. The sum relative error (SRE of optimum method ranged between −2 and +4% for four-gap level at three sites, except for 55% gaps at soybean site, which also obviously reduced standard deviation of error.

  7. In vivo modulation of rat distal tubule net HCO3 flux by VIP, isoproterenol, angiotensin II, and ADH.

    Science.gov (United States)

    Levine, D Z; Iacovitti, M; Buckman, S; Harrison, V

    1994-06-01

    To examine the in vivo effects of agonists reported to influence bicarbonate flux (JtCO2), microperfusion experiments were carried out on distal tubules of normally fed or overnight-fasted rats. As we previously reported, distal tubules from fed rats reabsorbed no bicarbonate, whereas overnight-fasted rats consistently reabsorbed bicarbonate (JtCO2 10 +/- 3 pmol.min-1.mm-1; P < 0.01). Vasoactive intestinal peptide and isoproterenol infused intravenously (7.3 and 4.0 micrograms.kg-1.h-1, respectively) in fasted rats suppressed JtCO2 and, in the case of vasoactive intestinal peptide, elicited net bicarbonate secretion (JtCO2 -10 +/- 2 and -4 +/- 4 pmol.min-1.mm-1, respectively). In fed rats, angiotensin II infused at a rate of 1.2 micrograms.kg-1.h-1 stimulated bicarbonate reabsorption (JtCO2 16 +/- 3 pmol.min-1.mm-1), while antidiuretic hormone infused at 0.024 micrograms.kg-1.h-1 elicited a similar response (17 +/- 4 pmol.min-1.mm-1), both values being significantly different from control. These results, therefore, demonstrate for the first time that these agonists can modulate JtCO2 at the distal tubule site in vivo and therefore may be potential regulators of systemic acid-base balance.

  8. The 30 cm radio flux as a solar proxy for thermosphere density modelling

    Directory of Open Access Journals (Sweden)

    Dudok de Wit Thierry

    2017-01-01

    Full Text Available The 10.7 cm radio flux (F10.7 is widely used as a proxy for solar UV forcing of the upper atmosphere. However, radio emissions at other centimetric wavelengths have been routinely monitored since the 1950 s, thereby offering prospects for building proxies that may be better tailored to space weather needs. Here we advocate the 30 cm flux (F30 as a proxy that is more sensitive than F10.7 to longer wavelengths in the UV and show that it improves the response of the thermospheric density to solar forcing, as modelled with DTM (Drag Temperature Model. In particular, the model bias drops on average by 0–20% when replacing F10.7 by F30; it is also more stable (the standard deviation of the bias is 15–40% smaller and the density variation at the the solar rotation period is reproduced with a 35–50% smaller error. We compare F30 to other solar proxies and discuss its assets and limitations.

  9. Solar Coronal Heating and the Magnetic Flux Content of the Network

    Science.gov (United States)

    Moore, R. L.; Falconer, D. A.; Porter, J. G.; Hathaway, D. H.

    2003-01-01

    We investigate the heating of the quiet corona by measuring the increase of coronal luminosity with the amount of magnetic flux in the underlying network at solar minimum when there were no active regions on the face of the Sun. The coronal luminosity is measured from Fe IX/X-Fe XII pairs of coronal images from SOHO/EIT. The network magnetic flux content is measured from SOHO/MDI magnetograms. We find that the luminosity of the corona in our quiet regions increases roughly in proportion to the square root of the magnetic flux content of the network and roughly in proportion to the length of the perimeter of the network magnetic flux clumps. From (1) this result, (2) other observations of many fine-scale explosive events at the edges of network flux clumps, and (3) a demonstration that it is energetically feasible for the heating of the corona in quiet regions to be driven by explosions of granule-sized sheared-core magnetic bipoles embedded in the edges of network flux clumps, we infer that in quiet regions that are not influenced by active regions the corona is mainly heated by such magnetic activity in the edges of the network flux clumps. Our observational results together with our feasibility analysis allow us to predict that (1) at the edges of the network flux clumps there are many transient sheared-core bipoles of the size and lifetime of granules and having transverse field strengths greater than approximately - 100 G, (2) approximately 30 of these bipoles are present per supergranule, and (3) most spicules are produced by explosions of these bipoles.

  10. Remote sensing as a tool for watershed-wide estimation of net solar radiation and water loss to the atmosphere

    Science.gov (United States)

    Khorram, S.; Thomas, R. W.

    1976-01-01

    Results are presented for a study intended to develop a general remote sensing-aided cost-effective procedure to estimate watershed-wide water loss to the atmosphere via evapotranspiration and to estimate net solar radiation over the watershed. Evapotranspiration estimation employs a basic two-stage two-phase sample of three information resolution levels. Net solar radiation is taken as one of the variables at each level of evapotranspiration modeling. The input information for models requiring spatial information will be provided by Landsat digital data, environmental satellite data, ground meteorological data, ground sample unit information, and topographic data. The outputs of the sampling-estimation/data bank system will be in-place maps of evapotranspiration on a data resolution element basis, watershed-wide evapotranspiration isopleths, and estimates of watershed and subbasin total evapotranspiration with associated statistical confidence bounds. The methodology developed is being tested primarily on the Spanish Creek Watershed Plumas County, California.

  11. A model to calculate solar radiation fluxes on the Martian surface

    Directory of Open Access Journals (Sweden)

    Vicente-Retortillo Álvaro

    2015-01-01

    Full Text Available We present a new comprehensive radiative transfer model to study the solar irradiance that reaches the surface of Mars in the spectral range covered by MetSIS, a sensor aboard the Mars MetNet mission that will measure solar irradiance in several bands from the ultraviolet (UV to the near infrared (NIR. The model includes up-to-date wavelength-dependent radiative properties of dust, water ice clouds, and gas molecules. It enables the characterization of the radiative environment in different spectral regions under different scenarios. Comparisons between the model results and MetSIS observations will allow for the characterization of the temporal variability of atmospheric optical depth and dust size distribution, enhancing the scientific return of the mission. The radiative environment at the Martian surface has important implications for the habitability of Mars as well as a strong impact on its atmospheric dynamics and climate.

  12. Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions

    Directory of Open Access Journals (Sweden)

    Mike Lockwood

    2013-09-01

    Full Text Available Historic geomagnetic activity observations have been used to reveal centennial variations in the open solar flux and the near-Earth heliospheric conditions (the interplanetary magnetic field and the solar wind speed. The various methods are in very good agreement for the past 135 years when there were sufficient reliable magnetic observatories in operation to eliminate problems due to site-specific errors and calibration drifts. This review underlines the physical principles that allow these reconstructions to be made, as well as the details of the various algorithms employed and the results obtained. Discussion is included of: the importance of the averaging timescale; the key differences between “range” and “interdiurnal variability” geomagnetic data; the need to distinguish source field sector structure from heliospherically-imposed field structure; the importance of ensuring that regressions used are statistically robust; and uncertainty analysis. The reconstructions are exceedingly useful as they provide calibration between the in-situ spacecraft measurements from the past five decades and the millennial records of heliospheric behaviour deduced from measured abundances of cosmogenic radionuclides found in terrestrial reservoirs. Continuity of open solar flux, using sunspot number to quantify the emergence rate, is the basis of a number of models that have been very successful in reproducing the variation derived from geomagnetic activity. These models allow us to extend the reconstructions back to before the development of the magnetometer and to cover the Maunder minimum. Allied to the radionuclide data, the models are revealing much about how the Sun and heliosphere behaved outside of grand solar maxima and are providing a means of predicting how solar activity is likely to evolve now that the recent grand maximum (that had prevailed throughout the space age has come to an end.

  13. SOLAR PROMINENCES EMBEDDED IN FLUX ROPES: MORPHOLOGICAL FEATURES AND DYNAMICS FROM 3D MHD SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Terradas, J.; Soler, R.; Oliver, R.; Ballester, J. L. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Luna, M. [Instituto de Astrofsíca de Canarias, E-38205 La Laguna, Tenerife (Spain); Wright, A. N., E-mail: jaume.terradas@uib.es [School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS (United Kingdom)

    2016-04-01

    The temporal evolution of a solar prominence inserted in a three-dimensional magnetic flux rope is investigated numerically. Using the model of Titov and Démoulin under the regime of weak twist, the cold and dense prominence counteracts gravity by modifying the initially force-free magnetic configuration. In some cases a quasi-stationary situation is achieved after the relaxation phase, characterized by the excitation of standing vertical oscillations. These oscillations show a strong attenuation with time produced by the mechanism of continuum damping due to the inhomogeneous transition between the prominence and solar corona. The characteristic period of the vertical oscillations does not depend strongly on the twist of the flux rope. Nonlinearity is responsible for triggering the Kelvin–Helmholtz instability associated with the vertical oscillations and that eventually produces horizontal structures. Contrary to other configurations in which the longitudinal axis of the prominence is permeated by a perpendicular magnetic field, like in unsheared arcades, the orientation of the prominence along the flux rope axis prevents the development of Rayleigh–Taylor instabilities and therefore the appearance of vertical structuring along this axis.

  14. Sensitivity of boreal forest regional water flux and net primary production simulations to sub-grid-scale land cover complexity

    Science.gov (United States)

    Kimball, J. S.; Running, S. W.; Saatchi, S. S.

    1999-11-01

    We use a general ecosystem process model (BIOME-BGC) coupled with remote sensing information to evaluate the sensitivity of boreal forest regional evapotranspiration (ET) and net primary production (NPP) to land cover spatial scale. Simulations were conducted over a 3 year period (1994-1996) at spatial scales ranging from 30 to 50 km within the BOREAS southern modeling subarea. Simulated fluxes were spatially complex, ranging from 0.1 to 3.9 Mg C ha-1 yr-1 and from 18 to 29 cm yr-1. Biomass and leaf area index heterogeneity predominantly controlled this complexity, while biophysical differences between deciduous and coniferous vegetation were of secondary importance. Spatial aggregation of land cover characteristics resulted in mean monthly NPP estimation bias from 25 to 48% (0.11-0.20 g C m-2 d-1) and annual estimation errors from 2 to 14% (0.04-0.31 Mg C ha-1 yr-1). Error was reduced at longer time intervals because coarse scale overestimation errors during spring were partially offset by underestimation of fine scale results during summer and winter. ET was relatively insensitive to land cover spatial scale with an average bias of less than 5% (0.04 kg m-2 d-1). Factors responsible for differences in scaling behavior between ET and NPP included compensating errors for ET calculations and boreal forest spatial and temporal NPP complexity. Careful consideration of landscape spatial and temporal heterogeneity is necessary to identify and mitigate potential error sources when using plot scale information to understand regional scale patterns. Remote sensing data integrated within an ecological process model framework provides an efficient mechanism to evaluate scaling behavior, interpret patterns in coarse resolution data, and identify appropriate scales of operation for various processes.

  15. Estimation of Community Land Model parameters for an improved assessment of net carbon fluxes at European sites

    Science.gov (United States)

    Post, Hanna; Vrugt, Jasper A.; Fox, Andrew; Vereecken, Harry; Hendricks Franssen, Harrie-Jan

    2017-03-01

    The Community Land Model (CLM) contains many parameters whose values are uncertain and thus require careful estimation for model application at individual sites. Here we used Bayesian inference with the DiffeRential Evolution Adaptive Metropolis (DREAM(zs)) algorithm to estimate eight CLM v.4.5 ecosystem parameters using 1 year records of half-hourly net ecosystem CO2 exchange (NEE) observations of four central European sites with different plant functional types (PFTs). The posterior CLM parameter distributions of each site were estimated per individual season and on a yearly basis. These estimates were then evaluated using NEE data from an independent evaluation period and data from "nearby" FLUXNET sites at 600 km distance to the original sites. Latent variables (multipliers) were used to treat explicitly uncertainty in the initial carbon-nitrogen pools. The posterior parameter estimates were superior to their default values in their ability to track and explain the measured NEE data of each site. The seasonal parameter values reduced with more than 50% (averaged over all sites) the bias in the simulated NEE values. The most consistent performance of CLM during the evaluation period was found for the posterior parameter values of the forest PFTs, and contrary to the C3-grass and C3-crop sites, the latent variables of the initial pools further enhanced the quality-of-fit. The carbon sink function of the forest PFTs significantly increased with the posterior parameter estimates. We thus conclude that land surface model predictions of carbon stocks and fluxes require careful consideration of uncertain ecological parameters and initial states.

  16. Effects of solar radiation on the abiotic and bacterially mediated carbon flux in aquatic ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Anesio, A.M.

    2000-05-01

    In this thesis, I studied some of the current aspects of organic matter photochemistry. I analyzed abiotic photo transformations of several types of dissolved (DOM) and particulate organic matter (POM). I also evaluated the effects of photo transformation of several types of DOM on bacteria. Finally, in a field experiment, I analyzed net effects of solar radiation on organic matter decomposition. DOM undergoes several transformations due to solar irradiation. One such transformation is photooxidation of organic matter into inorganic carbon. Results of this Thesis show that photooxidation is ubiquitous to all kinds of organic matter in both dissolved and particulate forms. The intensity of this process depends on several factors, including DOM composition, radiation type and time of exposure. Besides mineralization to inorganic carbon, DOM undergoes other chemical transformations due to UV radiation, with profound consequences to DOM availability for bacteria. Bioavailability was tested by measuring bacterial growth and respiration on irradiated and nonirradiated DOM from several types of humic matter and plant leachates. Irradiation of freshly-leached DOM often produced negative effects on bacteria, whereas irradiation of humic material was followed by stimulation of bacterial growth. The degree of stimulation seems to be related to the initial bioavailability of the DOM and to the capability of the DOM to produce hydrogen peroxide upon irradiation. Other factors also accounted for differences in bacterial response to photochemical modification of DOM, including length and type of irradiation exposure. The effects of solar radiation on litter decomposition were also evaluated using experiments that more closely mimic natural conditions. I could not observe differences between dry weight loss of leaves and culms exposed to solar radiation or kept in darkness, which may be explained by the fact that abiotic decomposition under solar radiation is counterbalanced by

  17. If sterile neutrinos exist, how can one determine the total 8B and 7Be solar neutrino fluxes?

    CERN Document Server

    Bahcall, J N; Peña-Garay, C; Bahcall, John N.

    2002-01-01

    The 8B solar neutrino flux inferred from solar neutrino experiments is within 33% (3sigma) of the predicted standard solar model value if only active neutrinos exist, but could be as large as 2.3 times the standard prediction if sterile neutrinos exist. We show that the total 8B neutrino flux (active plus sterile neutrinos) can be determined experimentally to about 11% (1 sigma) by combining charged current measurements made with the KamLAND reactor experiment and with the SNO solar neutrino experiment, provided the LMA neutrino oscillation solution is correct and the simulated performance of KamLAND is valid. Including also SNO NC data, the sterile component of the 8B neutrino flux can be measured by this method to an accuracy of about 14% (1 sigma) of the standard solar model flux. Combining Super-Kamiokande and KamLAND measurements and assuming the oscillations occur only among active neutrinos, the 8B neutrino flux can be measured to 4%(1 sigma); the total flux can be measured to an accuracy of about 14%....

  18. Effects of particle size and dry matter content of a total mixed ration on intraruminal equilibration and net portal flux of volatile fatty acids in lactating dairy cows

    DEFF Research Database (Denmark)

    Storm, Adam Christian; Kristensen, Niels Bastian

    2010-01-01

    ration (44.3 and 53.8%). The feed DM did not affect chewing time, ruminal variables, or net portal flux of VFA. However, decreasing the FPS decreased the overall chewing and rumination times by 151 ± 55 and 135 ± 29 min/d, respectively. No effect of the reduced chewing time was observed on ruminal p...

  19. Optical design of a high radiative flux solar furnace for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Riveros-Rosas, D.; Perez-Rabago, C.A.; Arancibia-Bulnes, C.A.; Jaramillo, O.A.; Estrada, C.A. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Av. Xochicalco s/n, A.P. 34, Temixco, 62580 Morelos (Mexico); Herrera-Vazquez, J.; Vazquez-Montiel, S.; Granados-Agustin, F. [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, A.P. 216, 72000 Puebla (Mexico); Sanchez-Gonzalez, M. [Centro Nacional de Energias Renovables, Calle Somera 7-9, 28026 Madrid (Spain)

    2010-05-15

    In the present work, the optical design of a new high radiative flux solar furnace is described. Several optical configurations for the concentrator of the system have been considered. Ray tracing simulations were carried out in order to determine the concentrated radiative flux distributions in the focal zone of the system, for comparing the different proposals. The best configuration was chosen in terms of maximum peak concentration, but also in terms of economical and other practical considerations. It consists of an arrangement of 409 first surface spherical facets with hexagonal shape, mounted on a spherical frame. The individual orientation of the facets is corrected in order to compensate for aberrations. The design considers an intercepted power of 30 kW and a target peak concentration above 10,000 suns. The effect of optical errors was also considered in the simulations. (author)

  20. Generation of twist on magnetic flux tubes at the base of the solar convection zone

    Science.gov (United States)

    Hotta, H.; Yokoyama, T.

    2012-12-01

    Using two-dimensional magnetohydrodynamics calculations, we investigate a twist generation mechanism on a magnetic flux tube at the base of the solar convection zone based on the idea of Choudhuri (2003, Sol. Phys., 215, 31) in which a toroidal magnetic field is wrapped by a surrounding mean poloidal field. During generation of the twist, the flux tube follows four phases. (1) It quickly splits into two parts with vortex motions rolling up the poloidal magnetic field. (2) Owing to the physical mechanism similar to that of the magneto-rotational instability, the rolled-up poloidal field is bent and amplified. (3) The magnetic tension of the disturbed poloidal magnetic field reduces the vorticity, and the lifting force caused by vortical motion decreases. (4) The flux tube gets twisted and begins to rise again without splitting. Investigation of these processes is significant because it shows that a flux tube without any initial twist can rise to the surface in relatively weak poloidal fields.

  1. Heating of coronal plasma by anomalous current dissipation. [induced by solar magnetic flux

    Science.gov (United States)

    Rosner, R.; Golub, L.; Coppi, B.; Vaiana, G. S.

    1978-01-01

    It is shown that there exist heating mechanisms which connect the observed radiative properties of the inner corona in a simple way to the underlying solar magnetic field. The mechanisms considered involve the generation and consequent dissipation of coronal currents. It is argued that the spatially and temporally inhomogeneous nature of the erupting solar magnetic field is an essential element of coronal heating. Unlike heating theories conceived in the context of the 'homogeneous' corona, this class of current heating models incorporates the observed stochastic coronal structuring at the onset, and does not view it as a complication of an otherwise straightforward model. Attention is given to the generation of coronal currents, the flux-tube emergence, the gradual growth and decay of active regions, the energetics of current dissipation, current sheath geometry and heat transport, and anomalous current dissipation.

  2. Parameters of solar wind electron heat-flux pitch-angle distributions and IMF topologies

    Science.gov (United States)

    Feuerstein, W. M.; Larson, D. E.; Luhmann, J. G.; Lin, R. P.; Kahler, S. W.; Crooker, N. U.

    2004-11-01

    Pitch-angle distributions (PADs) of solar wind heat-flux (HF) electrons are used as a proxy for interplanetary magnetic field (IMF) topology. Unidirectional PADs yield IMF solar polarities, and bidirectional electron (BDE) PADs are interpreted as signatures of closed fields. A general perception exists that the directionalities are easily distinguished, clearly defining open and closed IMFs. We quantify PADs with the ratios of the HF parallel and anti-parallel to the IMF to that perpendicular to the IMF plotting these parameters against each other in a directionality distribution for six years of electron data from the 3DP experiment on the Wind satellite. This bimodal plot clearly shows the unidirectional populations, but shows no evidence for a separate bidirectional HF population. A similar plot of magnetic clouds is double-banded with no evidence of a bifurcation between bidirectional and unidirectional regimes. In conclusion, this basic parameterization shows no distinction between open and closed field topologies.

  3. Properties of Longitudinal Flux Tube Waves. III; Wave Propagation in Solar and Stellar Wind FLows

    Science.gov (United States)

    Cuntz, M.; Suess, S. T.

    2004-01-01

    We discuss the analytic properties of longitudinal tube waves taking into account ambient wind flows. This is an extension of the studies of Papers I and II, which assumed a mean flow speed of zero and also dealt with a simplified horizontal pressure balance. Applications include the study of longitudinal flux tube waves in stars with significant mass loss and the heating and dynamics of plumes in the solar wind. Slow magnetosonic waves, also called longitudinal waves, have been observed in solar plumes and are likely an important source of heating. We show that the inclusion of ambient wind flows considerably alters the limiting shock strength as well as the energy damping length of the waves.

  4. Twist accumulation and topology structure of a solar magnetic flux rope

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Ding, M. D.; Cheng, X. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Zhao, J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Pariat, E., E-mail: guoyang@nju.edu.cn [LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, F-92190 Meudon (France)

    2013-12-20

    To study the buildup of a magnetic flux rope before a major flare and coronal mass ejection (CME), we compute the magnetic helicity injection, twist accumulation, and topology structure of the three-dimensional (3D) magnetic field, which is derived by the nonlinear force-free field model. The Extreme-ultraviolet Imaging Telescope on board the Solar and Heliospheric Observatory observed a series of confined flares without any CME before a major flare with a CME at 23:02 UT on 2005 January 15 in active region NOAA 10720. We derive the vector velocity at eight time points from 18:27 UT to 22:20 UT with the differential affine velocity estimator for vector magnetic fields, which were observed by the Digital Vector Magnetograph at Big Bear Solar Observatory. The injected magnetic helicity is computed with the vector magnetic and velocity fields. The helicity injection rate was (– 16.47 ± 3.52) × 10{sup 40} Mx{sup 2} hr{sup –1}. We find that only about 1.8% of the injected magnetic helicity became the internal helicity of the magnetic flux rope, whose twist increasing rate was –0.18 ± 0.08 Turns hr{sup –1}. The quasi-separatrix layers (QSLs) of the 3D magnetic field are computed by evaluating the squashing degree, Q. We find that the flux rope was wrapped by QSLs with large Q values, where the magnetic reconnection induced by the continuously injected magnetic helicity further produced the confined flares. We suggest that the flux rope was built up and heated by the magnetic reconnection in the QSLs.

  5. A semi-analytical computation of the theoretical uncertainties of the solar neutrino flux

    DEFF Research Database (Denmark)

    Jorgensen, Andreas C. S.; Christensen-Dalsgaard, Jorgen

    2017-01-01

    We present a comparison between Monte Carlo simulations and a semi-analytical approach that reproduces the theoretical probability distribution functions of the solar neutrino fluxes, stemming from the pp, pep, hep, Be-7, B-8, N-13, O-15 and F-17 source reactions. We obtain good agreement between...... the two approaches. Thus, the semi-analytical method yields confidence intervals that closely match those found, based on Monte Carlo simulations, and points towards the same general symmetries of the investigated probability distribution functions. Furthermore, the negligible computational cost...

  6. Propagation of nonlinear, radiatively damped longitudinal waves along magnetic flux tubes in the solar atmosphere

    Science.gov (United States)

    Herbold, G.; Ulmschneider, P.; Spruit, H. C.; Rosner, R.

    1985-01-01

    For solar magnetic flux tubes three types of waves are compared: longitudinal MHD tube waves, acoustic tube waves propagating in the same tube geometry but with rigid walls and ordinary acoustic waves in plane geometry. It is found that the effect of the distensibility of the tube is small and that longitudinal waves are essentially acoustic tube waves. Due to the tube geometry there is considerable difference between longitudinal waves or acoustic tube waves and ordinary acoustic waves. Longitudinal waves as well as acoustic tube waves show a smaller amplitude growth, larger shock formation heights, smaller mean chromospheric temperature but a steeper dependence of the temperature gradient on wave period.

  7. Forecasting F10.7 with Solar Magnetic Flux Transport Modeling (Postprint)

    Science.gov (United States)

    2012-04-03

    22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to any penalty for failing to...Power law relating 10.7 cm flux to sunspot number, Astrophys. Space Sci., 332, 73–79, doi:10.1007/s10509-010- 0500-1. Jones, H. P., T. L. Duvall Jr., J. W...2009JD012375. Lean, J. L., J. M. Picone, and J. T. Emmert (2009), Quantitative fore- casting of near-term solar activity and upper atmospheric density, J

  8. Stratospheric O3 changes during 2001–2010: the small role of solar flux variations in a chemical transport model

    Directory of Open Access Journals (Sweden)

    S. S. Dhomse

    2013-10-01

    Full Text Available Solar spectral fluxes (or irradiance measured by the SOlar Radiation and Climate Experiment (SORCE show different variability at ultraviolet (UV wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S. Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008 can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM, forced by meteorology from the European Centre for Medium-Range Weather Forecasts (ECMWF, to simulate middle atmospheric O3 using three different solar flux data sets (SORCE, NRL-SSI and SATIRE-S. Simulated O3 changes are compared with Microwave Limb Sounder (MLS and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER satellite data. Modelled O3 anomalies from all solar flux data sets show good agreement with the observations, despite the different flux variations. The off-line CTM reproduces these changes through dynamical information contained in the analyses. A notable feature during this period is a robust positive solar signal in the tropical middle stratosphere, which is due to realistic dynamical changes in our simulations. Ozone changes in the lower mesosphere cannot be used to discriminate between solar flux data sets due to large uncertainties and the short time span of the observations. Overall this study suggests that, in a CTM, the UV variations detected by SORCE are not necessary to reproduce observed stratospheric O3 changes during 2001–2010.

  9. Multifractal scaling of the kinetic energy flux in solar wind turbulence

    Science.gov (United States)

    Marsch, E.; Rosenbauer, H.; Tu, C.-Y.

    1995-01-01

    The geometrical and scaling properties of the energy flux of the turbulent kinetic energy in the solar wind have been studied. By present experimental technology in solar wind measurements, we cannot directly measure the real volumetric dissipation rate, epsilon(t), but are constrained to represent it by surrogating the energy flux near the dissipation range at the proton gyro scales. There is evidence for the multifractal nature of the so defined dissipation field epsilon(t), a result derived from the scaling exponents of its statistical q-th order moments. The related generalized dimension D(q) has been determined and reveals that the dissipation field has a multifractal structure. which is not compatible with a scale-invariant cascade. The associated multifractal spectrum f(alpha) has been estimated for the first time for MHD turbulence in the solar wind. Its features resemble those obtained for turbulent fluids and other nonlinear multifractal systems. The generalized dimension D(q) can, for turbulence in high-speed streams, be fitted well by the functional dependence of the p-model with a comparatively large parameter, p = 0.87. indicating a strongly intermittent multifractal energy cascade. The experimental value for D(p)/3, if used in the scaling exponent s(p) of the velocity structure function, gives an exponent that can describe some of the observations. The scaling exponent mu of the auto correlation function of epsilon(t) has also been directly evaluated. It has the value of 0.37. Finally. the mean dissipation rate was determined, which could be used in solar wind heating models.

  10. New predictive impact on cancer formation related to solar neutrinos flux crossing the human body

    Science.gov (United States)

    Meer, Sneer

    2001-08-01

    The aim of this paper is to study a new predictive impact on Cancer Formation constituted by the Solar Neutrinos Flux. Billions of Solar Neutrinos particles cross the human body each second without our feeling anything, and this phenomenon can give a valid reply to three basic questions on Cancer Formation such as: 1. Why Cancer appears at all types of cells 2. Why Cancer appears at all ages 3. Why Cancer appears in all segments of the human body It is experimentally proved that Solar Neutrinos interact with an atom of Chlorine 37, converting this stable atom in an unstable radioactive atom as Argon 37, and Molybdenum, is converted under Solar Neutrinos Flux in a radioactive atom of Technitium, Gallium 71 is converted into an unstable radioactive atom of Germanium, and I think that the list is not closed. It is well known that Chlorine 37 atoms and others are found in each cell in the human body assuring the vital metabolism of all our cells and astrophysicists experiments related to this subject of Chlorine 37 have a crucial importance for general medical sciences also especially in the field of Cancer diseases. Today, for the first time in the world, studies in Cancer Formation under Neutrinos Effects crossing the human body, can be made as soon as possible under an International and an Interdisciplinary Cooperation with special equipment such as the Biocassette-Telebiological-Microscopy (BTM) and its versatility, presented in this paper with some preliminary experiments. The purpose of this BTM system is to be able to see and follow in a continuous and dynamic form by Video-TV-Recorder system any changes or transformations of a normal human cell into a malignant cell in all its forms. Results will be concluded after this first proposal of such first kinds of experiments in the Medical Field related to a Common Denominator in Cancer.

  11. Angrite meteorites record the onset and flux of water to the inner solar system

    Science.gov (United States)

    Sarafian, Adam R.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Hauri, Erik H.; Righter, Kevin; Sarafian, Emily

    2017-09-01

    Earth and the other rocky bodies that make up the inner solar system are systematically depleted in hydrogen (H) and other cosmochemically volatile elements (e.g., carbon (C), fluorine (F), chlorine (Cl), and thallium (Tl)) relative to primitive undifferentiated meteorites known as carbonaceous chondrites. If we are to understand how and when Earth gained its life-essential elements, it is critical to determine the timing, flux, and nature of the delivery of condensed volatiles into the presumed hot and dry early inner solar system. Here we present evidence preserved in ancient basaltic angrite meteorites for an addition of volatiles to the hot and dry inner solar system within the first two million years of solar system history. Our data demonstrate that the angrite parent body was enriched in highly volatile elements (H, C, F, and Tl) relative to those predicted on the basis of the angrite parent body's overall volatile depletion trend (e.g., H is enriched by up to a factor of 106). This relative enrichment is best explained by mixing of extremely volatile-depleted material, located well inside the snow line, with volatile-rich material derived from outside the snow line.

  12. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

  13. Global and Regional Climate Responses Solar Radiation Management: Results from a climateprediction.net Geoengineering Experiment

    Science.gov (United States)

    Ricke, Katharine; Allen, Myles; Ingram, William; Keith, David; Granger Morgan, M.

    2010-05-01

    To date modeling studies suggest that, while significant hydrological anomalies could result from the artificial addition of reflecting aerosols in the stratosphere for the purpose of solar radiation management (SRM), even at the regional level such a geoengineered world would bear a much closer resemblance to a low CO2 world, than to an unmodified high CO2 world. These previous modeling studies have generally compared one or two SRM forcing scenarios to various business-as-usual controls. However, such approaches cannot provide much information about regional sensitivities to the levels of SRM that might realistically result. Should engaging in SRM every be seriously contemplated, such regional analysis of a range of realistic scenarios will be an essential input to any process of geopolitical decision-making. Here we present the results from a large-ensemble experiment that used the HadCM3L GCM, implemented through climateprediction.net. The analysis examines 135 globally-uniform stratospheric optical depth modification scenarios designed to stabilize global temperatures under SRES A1B. Scenarios were tested using ten-member subensembles which made small perturbations to initial conditions. All simulations use identical standard settings of model physics parameters and are initiated from historically-forced runs from 1920-2005. A total of 7,331 simulations of the years 2000-2080 were performed for this experiment using computing resources donated by the general public. Our analysis of regional temperature and precipitation anomalies, normalized to account for variability, shows that SRM compensations for anthropogenic greenhouse gas forcing do generally return regional climates closer to their baseline climate states than the no-geoengineering, business-as-usual scenarios. However, we find that the magnitudes and sensitivities of regional responses to this type of activity, as modeled in HadCM3L, are highly variable. As the amount of SRM increases to compensate

  14. A Proposed Paradigm for Solar Cycle Dynamics Mediated via Turbulent Pumping of Magnetic Flux in Babcock-Leighton-type Solar Dynamos

    Science.gov (United States)

    Hazra, Soumitra; Nandy, Dibyendu

    2016-11-01

    At present, the Babcock-Leighton flux transport solar dynamo models appear to be the most promising models for explaining diverse observational aspects of the sunspot cycle. The success of these flux transport dynamo models is largely dependent upon a single-cell meridional circulation with a deep equatorward component at the base of the Sun’s convection zone. However, recent observations suggest that the meridional flow may in fact be very shallow (confined to the top 10% of the Sun) and more complex than previously thought. Taken together, these observations raise serious concerns on the validity of the flux transport paradigm. By accounting for the turbulent pumping of magnetic flux, as evidenced in magnetohydrodynamic simulations of solar convection, we demonstrate that flux transport dynamo models can generate solar-like magnetic cycles even if the meridional flow is shallow. Solar-like periodic reversals are recovered even when meridional circulation is altogether absent. However, in this case, the solar surface magnetic field dynamics does not extend all the way to the polar regions. Very importantly, our results demonstrate that the Parker-Yoshimura sign rule for dynamo wave propagation can be circumvented in Babcock-Leighton dynamo models by the latitudinal component of turbulent pumping, which can generate equatorward propagating sunspot belts in the absence of a deep, equatorward meridional flow. We also show that variations in turbulent pumping coefficients can modulate the solar cycle amplitude and periodicity. Our results suggest the viability of an alternate magnetic flux transport paradigm—mediated via turbulent pumping—for sustaining solar-stellar dynamo action.

  15. Interacting effects of elevated temperature and additional water on plant physiology and net ecosystem carbon fluxes in a high Arctic ecosystem

    Science.gov (United States)

    Maseyk, Kadmiel; Seibt, Ulrike; Lett, Céline; Lupascu, Massimo; Czimczik, Claudia; Sullivan, Patrick; Welker, Jeff

    2013-04-01

    Arctic ecosystems are experiencing temperature increases more strongly than the global average, and increases in precipitation are also expected amongst the climate impacts on this region in the future. These changes are expected to strongly influence plant physiology and soil biogeochemistry with subsequent implications for system carbon balance. We have investigated the effects of a long-term (10 years) increase in temperature, soil water and the combination of both on a tundra ecosystem at a field manipulation experiment in NW Greenland. Leaf gas exchange, chlorophyll fluorescence, carbon (C) and nitrogen (N) content and leaf isotopic composition, and leaf morphology were measured on Salix arctica plants in treatment and control plots in June-July 2011, and continuous measurements of net plant and soil fluxes of CO2 and water were made using automatic chambers coupled to a trace gas laser analyzer. Plants in the elevated temperature (T2) treatment had the highest photosynthetic capacity in terms of net CO2 assimilation rates and photosystem II efficiencies, and lowest rates of non-photochemical energy dissipation during photosynthesis. T2 plants also had the highest leaf N content, specific leaf area (SLA) and saturation light level of photosynthesis. It appears that warming increases soil N availability, which the plants direct towards increasing photosynthetic capacity and producing larger thinner leaves. On the other hand, the plants in the plots with both elevated temperatures and additional water (T2W) had the lowest photosystem II efficiencies and the highest rates of non-photochemical energy dissipation, due more to higher levels of constitutive energy dissipation than regulated thermal quenching. Watering, both in combination with higher temperatures and alone (W treatment), also reduced leaf SLA and leaf N relative to control plots. However, net photosynthetic rates remained similar to control plants, due in part to higher stomatal conductance (W) and

  16. Modification of vortex dynamics and transport properties of transitional axisymmetric jets using zero-net-mass-flux actuation

    Energy Technology Data Exchange (ETDEWEB)

    Önder, Asim; Meyers, Johan, E-mail: johan.meyers@mech.kuleuven.be [Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300A, B3001 Leuven (Belgium)

    2014-07-15

    We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub μ} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.

  17. Effect of solar flares flux on the propagation and modal composition of VLF signal in the lower ionosphere

    Science.gov (United States)

    Bouderba, Yasmina; Nait Amor, Samir; Tribeche, Mouloud

    2015-04-01

    The VLF radio waves propagating in the Earth-Ionosphere waveguide are sensitive to the ionospheric disturbances due to X rays solar flux. In order to understand the VLF signal response to the solar flares, the LWPC code is used to simulate the signal perturbation parameters (amplitude and phase) at fixed solar zenith angle. In this work, we used the NRK-Algiers signal data and the study was done for different flares classes. The results show that the perturbed parameters increase with the increasing solar flares flux. This increases is due to the growth of the electron density resulting from the changes of the Wait's parameters. However, the behavior of the perturbation parameters as function of distance shows different forms of signal perturbations. It was also observed that the null points move towards the transmitter location when the flare flux increases which is related to the modal composition of the propagating signal. Effectively, for a given mode, the plot of the attenuation coefficient as function of the flare flux shows a decreases when the flux increases which is more significant for high modes. Thus, the solar flares effect is to amplify the VLF signal by reducing the attenuation coefficient.

  18. O2 absorption cross sections /187-225 nm/ from stratospheric solar flux measurements

    Science.gov (United States)

    Herman, J. R.; Mentall, J. E.

    1982-10-01

    The absorption cross sections of molecular oxygen are calculated in the wavelength range from 187 to 230 nm from solar flux measurements obtained within the stratosphere. Within the Herzberg continuum wavelength region the molecular oxygen cross sections are found to be about 30% smaller than the laboratory results of Shardanand and Rao (1977) from 200 to 210 nm and about 50% smaller than those of Hasson and Nicholls (1971). At wavelengths longer than 210 nm the cross sections agree with those of Shardanand and Rao. The effective absorption cross sections of O2 in the Schumann-Runge band region from 187 to 200 nm are calculated and compared to the empirical fit given by Allen and Frederick (1982). The calculated cross sections indicate that the transmissivity of the atmosphere may be underestimated by the use of the Allen and Frederic cross sections between 195 and 200 nm. The ozone column content between 30 and 40 km and the relative ozone cross sections are determined from the same solar flux data set.

  19. A theoretical framework for the net land-to-atmosphere CO2 flux and its implications in the definition of "emissions from land-use change"

    Directory of Open Access Journals (Sweden)

    T. Gasser

    2013-06-01

    Full Text Available We develop a theoretical framework and analysis of the net land-to-atmosphere CO2 flux in order to discuss possible definitions of "emissions from land-use change". The terrestrial biosphere is affected by two perturbations: the perturbation of the global carbon-climate-nitrogen system (CCN with elevated atmospheric CO2, climate change and nitrogen deposition; and the land-use change perturbation (LUC. Here, we progressively establish mathematical definitions of four generic components of the net land-to-atmosphere CO2 flux. The two first components are the fluxes that would be observed if only one perturbation occurred. The two other components are due to the coupling of the CCN and LUC perturbations, which shows the non-linear response of the terrestrial carbon cycle. Thanks to these four components, we introduce three possible definitions of "emissions from land-use change" that are indeed used in the scientific literature, often without clear distinctions, and we draw conclusions as for their absolute and relative behaviors. Thanks to the OSCAR v2 model, we provide quantitative estimates of the differences between the three definitions, and we find that comparing results from studies that do not use the same definition can lead to a bias of up to 20% between estimates of those emissions. After discussion of the limitations of the framework, we conclude on the three major points of this study that should help the community to reconcile modeling and observation of emissions from land-use change. The appendix mainly provides more detailed mathematical expressions of the four components of the net land-to-atmosphere CO2 flux.

  20. A theoretical framework for the net land-to-atmosphere CO2 flux and its implications in the definition of "emissions from land-use change"

    Science.gov (United States)

    Gasser, T.; Ciais, P.

    2013-06-01

    We develop a theoretical framework and analysis of the net land-to-atmosphere CO2 flux in order to discuss possible definitions of "emissions from land-use change". The terrestrial biosphere is affected by two perturbations: the perturbation of the global carbon-climate-nitrogen system (CCN) with elevated atmospheric CO2, climate change and nitrogen deposition; and the land-use change perturbation (LUC). Here, we progressively establish mathematical definitions of four generic components of the net land-to-atmosphere CO2 flux. The two first components are the fluxes that would be observed if only one perturbation occurred. The two other components are due to the coupling of the CCN and LUC perturbations, which shows the non-linear response of the terrestrial carbon cycle. Thanks to these four components, we introduce three possible definitions of "emissions from land-use change" that are indeed used in the scientific literature, often without clear distinctions, and we draw conclusions as for their absolute and relative behaviors. Thanks to the OSCAR v2 model, we provide quantitative estimates of the differences between the three definitions, and we find that comparing results from studies that do not use the same definition can lead to a bias of up to 20% between estimates of those emissions. After discussion of the limitations of the framework, we conclude on the three major points of this study that should help the community to reconcile modeling and observation of emissions from land-use change. The appendix mainly provides more detailed mathematical expressions of the four components of the net land-to-atmosphere CO2 flux.

  1. Evidence for a Magnetic Flux Rope in Observations of a Solar Prominence-Cavity System

    Directory of Open Access Journals (Sweden)

    Patricia R. Jibben

    2016-03-01

    Full Text Available Coronal cavities are regions of low coronal emission that usually sit above solar prominences. These systems can exist for days or months before erupting. The magnetic structure of the prominence-cavity system during the quiescent period is important to understanding the pre-eruption phase. We describe observations of a coronal cavity situated above a solar prominence observed on the western limb as part of an Interface Region Imaging Spectrograph (IRIS and Hinode coordinated Observation Program (IHOP 264. During the observation run, an inflow of hot plasma observed by the Hinode X-Ray Telescope (XRT envelopes the coronal cavity and triggers an eruption of chromospheric plasma near the base of the prominence. During and after the eruption, bright X-ray emission forms within the cavity and above the prominence. IRIS and the Hinode EUV Imaging Spectrometer (EIS show strong blue shifts in both chromospheric and coronal lines during the eruption. The Hinode Solar Optical Telescope (SOT Ca II H-line data show bright emission during the ejection with complex, turbulent, flows near the prominence and along the cavity wall. These observations suggest a cylindrical flux rope best represents the cavity structure with the ejected material flowing along magnetic field lines supporting the cavity. We also find evidence for heating of the plasma inside the cavity after the flows. A model of the magnetic structure of the cavity comprised of a weakly twisted flux rope can explain the observed loops in the X-ray and EUV data. Observations from the Coronal Multichannel Polarimeter (CoMP are compared to predicted models and are inconclusive. We find that more sensitive measurements of the magnetic field strength along the line-of-sight are needed to verify this configuration.

  2. Simulated solar wind plasma interaction with the Martian exosphere: influence of the solar EUV flux on the bow shock and the magnetic pile-up boundary

    Directory of Open Access Journals (Sweden)

    R. Modolo

    2006-12-01

    Full Text Available The solar wind plasma interaction with the Martian exosphere is investigated by means of 3-D multi-species hybrid simulations. The influence of the solar EUV flux on the bow shock and the magnetic pile-up boundary is examined by comparing two simulations describing the two extreme states of the solar cycle. The hybrid formalism allows a kinetic description of each ions species and a fluid description of electrons. The ionization processes (photoionization, electron impact and charge exchange are included self-consistently in the model where the production rate is computed locally, separately for each ionization act and for each neutral species. The results of simulations are in a reasonable agreement with the observations made by Phobos 2 and Mars Global Surveyor spacecraft. The position of the bow shock and the magnetic pile-up boundary is weakly dependent of the solar EUV flux. The motional electric field creates strong asymmetries for the two plasma boundaries.

  3. Flux

    DEFF Research Database (Denmark)

    Ravn, Ib

    Med udgangspunkt i kompleksistetsforskning og studiet af selvorganiserende systemer beskriver lb Ravn den fysiske og biologiske evolution og menneskets udvikling. Han fortolker begreber som kultur, sprog, frihed, værdier, mening, smerte og det ondes problem i lyset af en procesbaseret ontologi...... kanalisering af den flux eller energi, der strømmer igennem os og giver sig til kende i vore daglige aktiviteter. Skal vores tanker, handlinger, arbejde, samvær og politiske liv organiseres efter stramme og faste regelsæt, uden slinger i valsen? Eller skal de tværtimod forløbe ganske uhindret af regler og bånd...

  4. Electron heat flux instability

    Science.gov (United States)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  5. A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1984-01-01

    Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  6. A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1986-01-01

    Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  7. The May 17, 2012 solar event: back-tracing analysis and flux reconstruction with PAMELA

    Science.gov (United States)

    Bruno, A.; Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bravar, U.; Cafagna, F.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; Christian, E. C.; De Donato, C.; de Nolfo, G. A.; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Lee, M.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergè, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Ryan, J. M.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stochaj, S.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.; Zverev, V. G.

    2016-02-01

    The PAMELA space experiment is providing first direct observations of Solar Energetic Particles (SEPs) with energies from about 80 MeV to several GeV in near-Earth orbit, bridging the low energy measurements by other spacecrafts and the Ground Level Enhancement (GLE) data by the worldwide network of neutron monitors. Its unique observational capabilities include the possibility of measuring the flux angular distribution and thus investigating possible anisotropies associated to SEP events. The analysis is supported by an accurate back-tracing simulation based on a realistic description of the Earth's magnetosphere, which is exploited to estimate the SEP energy spectra as a function of the asymptotic direction of arrival with respect to the Interplanetary Magnetic Field (IMF). In this work we report the results for the May 17, 2012 event.

  8. A semi-analytical computation of the theoretical uncertainties of the solar neutrino flux

    Science.gov (United States)

    Jørgensen, Andreas C. S.; Christensen-Dalsgaard, Jørgen

    2017-11-01

    We present a comparison between Monte Carlo simulations and a semi-analytical approach that reproduces the theoretical probability distribution functions of the solar neutrino fluxes, stemming from the pp, pep, hep, 7Be, 8B, 13N, 15O and 17F source reactions. We obtain good agreement between the two approaches. Thus, the semi-analytical method yields confidence intervals that closely match those found, based on Monte Carlo simulations, and points towards the same general symmetries of the investigated probability distribution functions. Furthermore, the negligible computational cost of this method is a clear advantage over Monte Carlo simulations, making it trivial to take new observational constraints on the input parameters into account.

  9. Parametric study on kink instabilities of twisted magnetic flux ropes in the solar atmosphere

    Science.gov (United States)

    Mei, Z. X.; Keppens, R.; Roussev, I. I.; Lin, J.

    2018-01-01

    Aims: Twisted magnetic flux ropes (MFRs) in the solar atmosphere have been researched extensively because of their close connection to many solar eruptive phenomena, such as flares, filaments, and coronal mass ejections (CMEs). In this work, we performed a set of 3D isothermal magnetohydrodynamic (MHD) numerical simulations, which use analytical twisted MFR models and study dynamical processes parametrically inside and around current-carrying twisted loops. We aim to generalize earlier findings by applying finite plasma β conditions. Methods: Inside the MFR, approximate internal equilibrium is obtained by pressure from gas and toroidal magnetic fields to maintain balance with the poloidal magnetic field. We selected parameter values to isolate best either internal or external kink instability before studying complex evolutions with mixed characteristics. We studied kink instabilities and magnetic reconnection in MFRs with low and high twists. Results: The curvature of MFRs is responsible for a tire tube force due to its internal plasma pressure, which tends to expand the MFR. The curvature effect of toroidal field inside the MFR leads to a downward movement toward the photosphere. We obtain an approximate internal equilibrium using the opposing characteristics of these two forces. A typical external kink instability totally dominates the evolution of MFR with infinite twist turns. Because of line-tied conditions and the curvature, the central MFR region loses its external equilibrium and erupts outward. We emphasize the possible role of two different kink instabilities during the MFR evolution: internal and external kink. The external kink is due to the violation of the Kruskal-Shafranov condition, while the internal kink requires a safety factor q = 1 surface inside the MFR. We show that in mixed scenarios, where both instabilities compete, complex evolutions occur owing to reconnections around and within the MFR. The S-shaped structures in current distributions

  10. Adaptive Rule-Based Piece-Wise Regression Models for Estimating Regional Net Ecosystem Exchange in Grassland and Shrubland Ecoregions Using Regional and Flux Tower Data

    Science.gov (United States)

    Fosnight, E. A.; Wylie, B. K.; Zhang, L.

    2005-12-01

    The scientific understanding of the global carbon cycle requires quantitative documentation, monitoring, and projection of carbon stocks and fluxes at various scales across the landscape. The challenge is to develop predictive models using carbon flux towers at site-specific locations, and to extrapolate these models to landscapes and regions. We use remote sensing and national climate and soil databases within data-driven models to estimate carbon fluxes. To accommodate the study of coupled human-environmental relationships and their influences on carbon dynamics, a coherent suite of models is being developed for agricultural, wooded and wetland ecosystems within predominantly grassland and shrubland ecoregions. In previous work, we have mapped carbon fluxes in terms of Net Ecosystem Exchange (NEE), Gross Primary Production (GPP), and Respiration (Re) in the Northern Great Plains, the Sagebrush Steppes and the Kazakh Steppes at 1-km resolution and 10-day time steps. We now extend this work beyond fairly uniform ecological conditions to accommodate more complex spatial mixtures of ecological types within ecoregions. The models need to adapt to both the complexity of the environmental variables and the land cover patterns. Our rule-based models adapt to local climatic, soil and phenology through the definition of piece-wise regression models. A suite of such models is needed to capture the phenologic and climatic variability across the wide range of shrubland and grassland ecoregions that exist. The result is a multi-year time series of 1-km maps of carbon flux that are suitable for trend and anomaly analysis. We seek sensitive models that permit the effective study of localized carbon dynamics while avoiding over-fitting the available carbon flux tower measurement data. Two critical components of the project are (1) sensitivity and cross-validation studies to evaluate the internal consistencies of the models and (2) intercomparison studies to help isolate

  11. Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States

    Science.gov (United States)

    Xueri Dang; Chun-Ta Lai; David Y. Hollinger; Andrew J. Schauer; Jingfeng Xiao; J. William Munger; Clenton Owensby; James R. Ehleringer

    2011-01-01

    We evaluated an idealized boundary layer (BL) model with simple parameterizations using vertical transport information from community model outputs (NCAR/NCEP Reanalysis and ECMWF Interim Analysis) to estimate regional-scale net CO2 fluxes from 2002 to 2007 at three forest and one grassland flux sites in the United States. The BL modeling...

  12. Low-energy solar neutrino spectroscopy with Borexino. Towards the detection of the solar pep and CNO neutrino flux

    Energy Technology Data Exchange (ETDEWEB)

    Maneschg, Werner

    2011-05-11

    Borexino is a large-volume organic liquid scintillator detector of unprecedented high radiopurity which has been designed for low-energy neutrino spectroscopy in real time. Besides the main objective of the experiment, the measurement of the solar {sup 7}Be neutrino flux, Borexino also aims at detecting solar neutrinos from the pep fusion process and from the CNO cycle. The detectability of these neutrinos is strictly connected to a successful rejection of all relevant background components. The identification and reduction of these background signals is the central subject of this dissertation. In the first part, contaminants induced by cosmic-ray muons and muon showers were analyzed. The dominant background is the cosmogenic radioisotope {sup 11}C. Its rate is {proportional_to}10 times higher than the expected combined pep and CNO neutrino rate in the preferred energy window of observation at [0.8,1.3] MeV. Since {sup 11}C is mostly produced under the release of a free neutron, {sup 11}C can be tagged with a threefold coincidence (TFC) consisting of the muon signal, the neutron capture and the subsequent {sup 11}C decay. By optimizing the TFC method and other rejection techniques, a {sup 11}C rejection efficiency of 80% was achieved. This led to a neutrino-to-background ratio of 1:1.7, whereby 61% of statistics is lost. The second part of the work concerns the study of the external background. Especially long-range 2.6 MeV gamma rays from {sup 208}Tl decays in the outer detector parts can reach the scintillator in the innermost region of the detector. For the determination of the resultant spectral shape, a custom-made {proportional_to}5 MBq {sup 228}Th source was produced and an external calibration was carried out for the first time. The obtained calibration data and the achieved {sup 11}C rejection efficiency will allow for the direct detection of solar pep and possibly also CNO neutrinos with Borexino. (orig.)

  13. Sunward Strahl: A Method to Unambiguously Determine Open Solar Flux from In Situ Spacecraft Measurements Using Suprathermal Electron Data

    Science.gov (United States)

    Owens, M. J.; Lockwood, M.; Riley, P.; Linker, J.

    2017-11-01

    A fraction of the magnetic flux which threads the photosphere reaches sufficient coronal altitude to be dragged out by the solar wind and form the heliospheric magnetic field (HMF). Directly measuring this "open solar flux" (OSF) component, however, is difficult. While OSF can be extrapolated from photospheric magnetic field measurements, the most direct method is from in situ spacecraft measurements of the HMF. The difficultly is unambiguously distinguishing between HMF which connects directly back to the Sun (the OSF) and that which is locally distorted by waves, turbulence, and near-Sun reconnection. Suitable temporal filtering of the data can remove such "noise," but the level of filtering cannot be known a priori and varies with solar cycle, solar wind types, etc. Here we use the suprathermal electron beam, or "strahl," to distinguish between different HMF topologies. As strahl moves antisunward on global scales, times when strahl is observed to be moving sunward indicate that the HMF is locally inverted. By subtracting the inverted HMF, we compute the OSF without need for arbitrary filtering of the data. We find that the OSF obtained in this manner is slightly larger than the proposed "kinematic correction" based on observed solar wind velocity structure, though in general agreement. Our new OSF estimate agrees with methods based wholly on HMF data, if the data are first used to compute approximately 1 day averages during solar minimum and approximately 3 day averages during solar maximum, stressing the point that the filter method is unreliable because the required characteristics vary.

  14. Is There a CME Rate Floor? CME and Magnetic Flux Values for the Last Four Solar Cycle Minima

    Science.gov (United States)

    Webb, D. F.; Howard, R. A.; St. Cyr, O. C.; Vourlidas, A.

    2017-12-01

    The recent prolonged activity minimum has led to the question of whether there is a base level of the solar magnetic field evolution that yields a “floor” in activity levels and also in the solar wind magnetic field strength. Recently, a flux transport model coupled with magneto-frictional simulations has been used to simulate the continuous magnetic field evolution in the global solar corona for over 15 years, from 1996 to 2012. Flux rope eruptions in the simulations are estimated (Yeates), and the results are in remarkable agreement with the shape of the SOlar Heliospheric Observatory/Large Angle and Spectrometric Coronagraph Experiment coronal mass ejection (CME) rate distribution. The eruption rates at the two recent minima approximate the observed-corrected CME rates, supporting the idea of a base level of solar magnetic activity. In this paper, we address this issue by comparing annual averages of the CME occurrence rates during the last four solar cycle minima with several tracers of the global solar magnetic field. We conclude that CME activity never ceases during a cycle, but maintains a base level of 1 CME every 1.5 to ∼3 days during minima. We discuss the sources of these CMEs.

  15. Sensitivity of the KM3NeT detector to neutrino fluxes from Galactic point-like sources

    NARCIS (Netherlands)

    Trovato, A.; Kooijman, P.; Coniglione, R.; Sapienza, P.

    2014-01-01

    The KM3NeT collaboration has started the implementation of the first phase of a cubic-kilometre-scale neutrino telescope in the Northern hemisphere with an integrated platform for Earth and deep sea sciences. The location in the Mediterranean Sea will allow for surveying a large part of the sky,

  16. Measurement of the Solar Neutrino Flux with an Array of Neutron Detectors in the Sudbury Neutrino Observatory

    CERN Document Server

    Jamieson, Blair

    2008-01-01

    The Sudbury Neutrino Observatory has measured the $^8$B solar neutrino flux using an array of 3He proportional counters. Results obtained using a Markov-Chain Monte-Carlo (MCMC) parameter estimation, integrating over a standard extended likelihood, yield effective neutrino fluxes of: phi_nc=5.54+0.33-0.31(stat)+0.36-0.34(syst) x 10^6 /cm^2/s, phi_cc=1.67+0.05-0.04(stat)+0.07-0.08(syst) x 10^6 /cm^2/s, and phi_es=1.77+0.24-0.21(stat)+0.09-0.10(syst) x 10^6 /cm^2/s. These measurements are in agreement with previous solar neutrino flux measurements, and with neutrino oscillation model results. Including these flux measurements in a global analysis of solar and reactor neutrino results yields an improved precision on the solar neutrino mixing angle of theta=34.4+1.3-1.2 degrees, and Delta m^2=7.59+0.19-0.21 eV^2.

  17. Solar Sustainable Heating, Cooling and Ventilation of a Net Zero Energy House

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Skrupskelis, Martynas; Olesen, Bjarne W.

    Present work addresses the heating, cooling and ventilation concerns of the Technical University of Denmark’s house, Fold, for Solar Decathlon Europe 2012. Various innovative approaches are investigated, namely, utilization of ground, photo-voltaic/thermal (PV/T) panels and phase change materials...... by the embedded pipes which are coupled with the ground. Ventilation is mainly used to control the humidity and to remove sensory and chemical pollution. PV/T panels enable the house to be a “plus” energy house. PV/T also yields to a solar fraction of 63% and 31% for Madrid and Copenhagen, respectively...

  18. Assessing the net effect of long-term drainage on a permafrost ecosystem through year-round eddy-covariance flux measurements

    Science.gov (United States)

    Kittler, F.; Heimann, M.; Goeckede, M.; Zimov, S. A.; Zimov, N.

    2014-12-01

    Permafrost regions in the Northern high latitudes play a key role in the carbon budget of the earth system because of their massive carbon reservoir and the uncertain feedback processes with future climate change. For an improved understanding of mechanisms and drivers dominating permafrost carbon cycling, more observations in high-latitude regions are needed. Particularly the contribution of wintertime fluxes to the annual carbon budget and the impact of disturbances on biogeochemical and biogeophysical ecosystem properties, and the resulting modification of the carbon cycle, have rarely been studied to date. In summer of 2013, we established a new eddy-covariance station for continuous, year-round monitoring of carbon fluxes and their environmental drivers near Cherskii in Northeast Siberia (68.75°N, 161.33°E). Parts of the observation area have been disturbed by drainage since 2004, altering the soil water conditions in a way that is expected for degrading ice-rich permafrost under a warming climate. With two eddy-covariance towers running in parallel over the disturbed (drained) area and a reference area nearby, respectively, we can directly infer the disturbance effect on the carbon cycle budgets and the dominating biogeochemical mechanisms. This study presents findings based on 16 months of continuous eddy-covariance CO2 flux measurements (July 2013 - October 2014) for both observation areas. At both towers, we observed systematic, non-zero flux contributions outside the growing seasons that significantly altered annual CO2 budgets. A direct comparison of fluxes between the two disturbance regimes indicates a net reduction of the sink strength for CO2 in the disturbed area during the growing season, mostly caused by reduced CO2 uptake with low water levels in late summer. Moreover, shifts in soil temperatures and snow cover caused by reduced soil water levels result in lower net CO2 emissions during the winter at the drained area, which is partly

  19. Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

    Digital Repository Service at National Institute of Oceanography (India)

    Martin, P.; Loeff, M.M.R. van der.; Cassar, N.; Vandromme, P.; d'Ovidio, F.; Stemmann, L.; Rengarajan, R.; Soares, M.A.; Gonzalez, H.E.; Ebersbach, F.; Lampitt, R.S.; Sanders, R.; Barnett, B.A.; Smetacek, V.; Naqvi, S.W.A.

    A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux...

  20. Formation of a Double-decker Magnetic Flux Rope in the Sigmoidal Solar Active Region 11520

    Science.gov (United States)

    Cheng, X.; Ding, M. D.; Zhang, J.; Sun, X. D.; Guo, Y.; Wang, Y. M.; Kliem, B.; Deng, Y. Y.

    2014-07-01

    In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s-1. The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.

  1. Quantification of industrial VOC emissions in China using Solar Occultation Flux (SOF)

    Science.gov (United States)

    Johansson, John; Mellqvist, Johan; Lingbo, Li

    2017-04-01

    As a part of a comprehensive measurement campaign in Beijing during the spring 2016, a two week study to quantify industrial VOC emissions from industrial sources using the Solar Occultation Flux (SOF) method was undertaken in Tianjin. Located approximately 100 km east of Beijing, Tianjin is the largest port in northern China and the largest hub of oil and petrochemical industries in the area. The aim of the study was to investigate how well industrial VOC emissions are accounted for in emission inventories, and the importance of these emissions for the formation of photochemical smog and secondary aerosols. The SOF method is based on absorption spectroscopy of direct infrared sunlight, which is performed from a measurement van, while driving through emission plumes containing the species of interest. Using the measured gas columns in the plume, GPS information of the movement of the van and wind measurements, the total flux of the species can be calculated. The method has previously been used to quantify VOC emissions from a large number of oil refineries and petrochemical industries in Europe, North America and the Middle East. Preliminary emission rates of alkanes as well as number of alkenes, such as ethene, propene, 1,3-butadiene and vinyl chloride has been compiled for most of the largest industrial sources in the Tianjin area. These emissions have been incorporated into a Lagrangian atmospheric chemistry model along simulated trajectories passing Tianjin on their way to Beijing. This has yielded some preliminary results for the total impact of these emissions on photochemical smog in the area.

  2. 3D GCM modelling of thermospheric nitric oxide during the 2003 Halloween Storm using high resolution solar flux data.

    Science.gov (United States)

    Dobbin, A.; Aylward, A.

    Radiative emission by excited nitric oxide NO is an important cooling mechanism in the lower thermosphere Numerical modelling of thermospheric temperatures must therefore include a realistic representation of NO densities At low latitudes the abundance of this key constituent is thought to be is directly related to the flux of solar soft X-ray radiation while at high latitudes NO is affected by the flux of precipitating electrons In the present study the coupled middle atmosphere and thermosphere CMAT general circulation model has been used to simulate the 11-day period from 23rd October to 3rd November 2003 During this time the Earth was subject to highly variable solar irradiance and extremely high levels of geomagnetic activity The 3D model used incorporates a complex ion and neutral chemical scheme including a detailed self consistent calculation of NO production and transport High-resolution solar flux data taken from the SOLAR2000 irradiance model is incorporated along with variable auroral energy inputs Predictions of the global distribution of nitric oxide in the lower thermosphere are presented along with thermospheric temperatures for the storm period

  3. Borexino: New results on the solar 8B-neutrino flux and outlook on pep- and CNO-neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Meindl, Quirin [TU Muenchen (Germany)

    2011-07-01

    Borexino is a 300 t liquid-scintillator detector designed for the real-time detection of solar neutrinos in the sub-MeV energy range. The experiment is taking data since August 2007 and has published the first real-time spectral measurements of solar {sup 7}Be-neutrinos. Based on the statistics of 3 years, Borexino has recently achieved new results for the solar {sup 8}B-neutrinos, measuring this rate down to an unprecedented energy threshold of 3 MeV. The measurements of the remaining solar neutrino fluxes of the pep-, CNO- and pp-neutrinos are currently under investigation. The talk presents the new {sup 8}B-neutrino results of Borexino and give an outlook on the current efforts on the measurements of the pep- and CNO-neutrinos.

  4. Process for reducing series resistance of solar-cell metal-contact systems with a soldering-flux etchant

    Science.gov (United States)

    Coyle, R.T.; Barrett, J.M.

    1982-05-04

    Disclosed is a process for substantially reducing the series resistance of a solar cell having a thick film metal contact assembly thereon while simultaneously removing oxide coatings from the surface of the assembly prior to applying solder therewith. The process includes applying a flux to the contact assembly and heating the cell for a period of time sufficient to substantially remove the series resistance associated with the assembly by etching the assembly with the flux while simultaneously removing metal oxides from said surface of said assembly.

  5. Formation of Cool and Warm Jets by Magnetic Flux Emerging from the Solar Chromosphere to Transition Region

    Science.gov (United States)

    Yang, Liping; Peter, Hardi; He, Jiansen; Tu, Chuanyi; Wang, Linghua; Zhang, Lei; Yan, Limei

    2018-01-01

    In the solar atmosphere, jets are ubiquitous at various spatial-temporal scales. They are important for understanding the energy and mass transports in the solar atmosphere. According to recent observational studies, the high-speed network jets are likely to be intermittent but continual sources of mass and energy for the solar wind. Here, we conduct a 2D magnetohydrodynamics simulation to investigate the mechanism of these network jets. A combination of magnetic flux emergence and horizontal advection is used to drive the magnetic reconnection in the transition region between a strong magnetic loop and a background open flux. The simulation results show that not only a fast warm jet, much similar to the network jets, is found, but also an adjacent slow cool jet, mostly like classical spicules, is launched. Differing from the fast warm jet driven by magnetic reconnection, the slow cool jet is mainly accelerated by gradients of both thermal pressure and magnetic pressure near the outer border of the mass-concentrated region compressed by the emerging loop. These results provide a different perspective on our understanding of the formation of both the slow cool jets from the solar chromosphere and the fast warm jets from the solar transition region.

  6. High-flux/high-temperature solar thermal conversion: technology development and advanced applications

    Directory of Open Access Journals (Sweden)

    Romero Manuel

    2016-01-01

    Full Text Available Solar Thermal Power Plants have generated in the last 10 years a dynamic market for renewable energy industry and a pro-active networking within R&D community worldwide. By end 2015, there are about 5 GW installed in the world, most of them still concentrated in only two countries, Spain and the US, though a rapid process of globalization is taking place in the last few years and now ambitious market deployment is starting in countries like South Africa, Chile, Saudi Arabia, India, United Arab Emirates or Morocco. Prices for electricity produced by today's plants fill the range from 12 to 16 c€/kWh and they are capital intensive with investments above 4000 €/kW, depending on the number of hours of thermal storage. The urgent need to speed up the learning curve, by moving forward to LCOE below 10 c€/kWh and the promotion of sun-to-fuel applications, is driving the R&D programmes. Both, industry and R&D community are accelerating the transformation by approaching high-flux/high-temperature technologies and promoting the integration with high-efficiency conversion systems.

  7. Atmospheric 14CO2 Constraints on and Modeling of Net Carbon Fluxes 06-ERD-031 An LLNL Exploratory Research in the Directorate's Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Guilderson, T P; Cameron-Smith, P; Bergmann, D; Graven, H D; Keeling, R; Boering, K; Caldeira, K

    2009-03-18

    A critical scientific question is: 'what are the present day sources and sinks of carbon dioxide (CO{sub 2}) in the natural environment, and how will these sinks evolve under rising CO{sub 2} concentrations and expected climate change and ecosystem response'? Sources and sinks of carbon dioxide impart their signature on the distribution, concentration, and isotopic composition of CO{sub 2}. Spatial and temporal trends (variability) provide information on the net surface (atmosphere to ocean, atmosphere to terrestrial biosphere) fluxes. The need to establish more reliable estimates of sources and sinks of CO{sub 2} has lead to an expansion of CO{sub 2} measurement programs over the past decade and the development of new methodologies for tracing carbon flows. These methodologies include high-precision pCO{sub 2}, {delta}{sup 13}CO{sub 2}, and [O{sub 2}/N{sub 2}] measurements on atmospheric constituents that, when combined, have allowed estimates of the net terrestrial and oceanic fluxes at decadal timescales. Major gaps in our understanding remain however, and resulting flux estimates have large errors and are comparatively unconstrained. One potentially powerful approach to tracking carbon flows is based on observations of the {sup 14}C/{sup 12}C ratio of atmospheric CO{sub 2}. This ratio can be used to explicitly distinguish fossil-fuel CO{sub 2} from other sources of CO{sub 2} and also provide constraints on the mass and turnover times of carbon in land ecosystems and on exchange rates of CO{sub 2} between air and sea. Here we demonstrated measurement of {sup 14}C/{sup 12}C ratios at 1-2{per_thousand} on archived and currently collected air samples. In parallel we utilized the LLNL-IMPACT global atmospheric chemistry transport model and the TransCom inversion algorithm to utilize these data in inversion estimates of carbon fluxes. This project has laid the foundation for a more expanded effort in the future, involving collaborations with other air

  8. Origin of the High-speed Jets Fom Magnetic Flux Emergence in the Solar Transition Region as well as Their Mass and Energy Contribuctions to the Solar Wind

    Science.gov (United States)

    Liping, Y.; He, J.; Peter, H.; Tu, C. Y.; Feng, X. S.

    2015-12-01

    In the solar atmosphere, the jets are ubiquitous and found to be at various spatia-temporal scales. They are significant to understand energy and mass transport in the solar atmosphere. Recently, the high-speed transition region jets are reported from the observation. Here we conduct a numerical simulation to investigate the mechanism in their formation, as well as their mass and energy contributions to the solar wind. Driven by the supergranular convection motion, the magnetic reconnection between the magnetic loop and the background open flux occurring in the transition region is simulated with a two-dimensional MHD model. The simulation results show that not only a fast hot jet, much resemble the found transition region jets, but also a adjacent slow cool jet, mostly like classical spicules, is launched. The force analysis shows that the fast hot jet is continually driven by the Lorentz force around the reconnection region, while the slow cool jet is induced by an initial kick through the Lorentz force associated with the emerging magnetic flux. Also, the features of the driven jets change with the amount of the emerging magnetic flux, giving the varieties of both jets.With the developed one-dimensional hydrodynamic solar wind model, the time-dependent pulses are imposed at the bottom to simulate the jet behaviors. The simulation results show that without other energy source, the injected plasmas are accelerated effectively to be a transonic wind with a substantial mass flux. The rapid acceleration occurs close to the Sun, and the resulting asymptotic speeds, number density at 0.3 AU, as well as mass flux normalized to 1 AU are compatible with in site observations. As a result of the high speed, the imposed pulses lead to a train of shocks traveling upward. By tracing the motions of the injected plasma, it is found that these shocks heat and accelerate the injected plasma to make part of them propagate upward and eventually escape. The parametric study shows

  9. Generation of daily solar irradiation by means of artificial neural net works

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, Adalberto N.; Tiba, Chigueru; Fraidenraich, Naum [Departamento de Energia Nuclear, da Universidade Federal de Pernambuco, Av. Prof. Luiz Freire, 1000 - CDU, CEP 50.740-540 Recife, Pernambuco (Brazil)

    2010-11-15

    The present study proposes the utilization of Artificial Neural Networks (ANN) as an alternative for generating synthetic series of daily solar irradiation. The sequences were generated from the use of daily temporal series of a group of meteorological variables that were measured simultaneously. The data used were measured between the years of 1998 and 2006 in two temperate climate localities of Brazil, Ilha Solteira (Sao Paulo) and Pelotas (Rio Grande do Sul). The estimates were taken for the months of January, April, July and October, through two models which are distinguished regarding the use or nonuse of measured bright sunshine hours as an input variable. An evaluation of the performance of the 56 months of solar irradiation generated by way of ANN showed that by using the measured bright sunshine hours as an input variable (model 1), the RMSE obtained were less or equal to 23.2% being that of those, although 43 of those months presented RMSE less or equal to 12.3%. In the case of the model that did not use the measured bright sunshine hours but used a daylight length (model 2), RMSE were obtained that varied from 8.5% to 37.5%, although 38 of those months presented RMSE less or equal to 20.0%. A comparison of the monthly series for all of the years, achieved by means of the Kolmogorov-Smirnov test (to a confidence level of 99%), demonstrated that of the 16 series generated by ANN model only two, obtained by model 2 for the months of April and July in Pelotas, presented significant difference in relation to the distributions of the measured series and that all mean deviations obtained were inferior to 0.39 MJ/m{sup 2}. It was also verified that the two ANN models were able to reproduce the principal statistical characteristics of the frequency distributions of the measured series such as: mean, mode, asymmetry and Kurtosis. (author)

  10. RADIO DIAGNOSTICS OF ELECTRON ACCELERATION SITES DURING THE ERUPTION OF A FLUX ROPE IN THE SOLAR CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Carley, Eoin P.; Gallagher, Peter T. [Astrophysics Research Group, School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Vilmer, Nicole, E-mail: eoin.carley@obspm.fr [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France)

    2016-12-10

    Electron acceleration in the solar corona is often associated with flares and the eruption of twisted magnetic structures known as flux ropes. However, the locations and mechanisms of such particle acceleration during the flare and eruption are still subject to much investigation. Observing the exact sites of particle acceleration can help confirm how the flare and eruption are initiated and how they evolve. Here we use the Atmospheric Imaging Assembly to analyze a flare and erupting flux rope on 2014 April 18, while observations from the Nançay Radio Astronomy Facility allow us to diagnose the sites of electron acceleration during the eruption. Our analysis shows evidence of a pre-formed flux rope that slowly rises and becomes destabilized at the time of a C-class flare, plasma jet, and the escape of ≳75 keV electrons from the rope center into the corona. As the eruption proceeds, continued acceleration of electrons with energies of ∼5 keV occurs above the flux rope for a period over 5 minutes. At the flare peak, one site of electron acceleration is located close to the flare site, while another is driven by the erupting flux rope into the corona at speeds of up to 400 km s{sup −1}. Energetic electrons then fill the erupting volume, eventually allowing the flux rope legs to be clearly imaged from radio sources at 150–445 MHz. Following the analysis of Joshi et al. (2015), we conclude that the sites of energetic electrons are consistent with flux rope eruption via a tether cutting or flux cancellation scenario inside a magnetic fan-spine structure. In total, our radio observations allow us to better understand the evolution of a flux rope eruption and its associated electron acceleration sites, from eruption initiation to propagation into the corona.

  11. Response of Earth's Atmosphere to Increases in Solar Flux and Implications for Loss of Water from Venus

    Science.gov (United States)

    Kasting, J. F.; Pollock, J. G.; Ackerman, T. P.

    1985-01-01

    A one dimensional radiative convective model is used to compute temperature and water vapor profiles as functions of solar flux for earthlike atmosphere. The troposphere is assumed to be fully saturated with a moist adiabatic lapse rate, and changes in cloudiness are neglected. Predicted surface temperatures increase monotonically from -1 to 111 C as the solar flux is increased from 0.81 to 1.45 times its present value. The results imply that the surface temperature of a primitive water rich Venus should have been at least 80-100 C and may have been much higher, water vapor should have been a major atmospheric constituent at all altitudes, leading to the rapid hydrodynamic escape of hydrogen. The oxygen left behind by this process was presumably consumed by reactions with reduced minerals in the crust.

  12. Observational Evidence for Self-generation of Small-scale Magnetic Flux Ropes from Intermittent Solar Wind Turbulence

    Science.gov (United States)

    Zheng, Jinlei; Hu, Qiang

    2018-01-01

    We present unique and additional observational evidence for the self-generation of small-scale coherent magnetic flux rope structures in the solar wind. Such structures with durations between 9 and 361 minutes are identified from Wind in situ spacecraft measurements through the Grad–Shafranov (GS) reconstruction approach. The event occurrence counts are on the order of 3500 per year on average and have a clear solar-cycle dependence. We build a database of small-scale magnetic flux ropes from 20 yr worth of Wind spacecraft data. We show a power-law distribution of the wall-to-wall time corresponding well to the inertial range turbulence, which agrees with relevant observations and numerical simulation results. We also provide the axial current density distribution from the GS-based observational analysis, which yields a non-Gaussian probability density function consistent with numerical simulation results.

  13. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...

  14. Summer extreme climatic event in the future: impact on the net CO2 and water fluxes of an upland grassland and buffering impact of elevated atmospheric CO2

    Science.gov (United States)

    Roy, Jacques; Ravel, Olivier; Landais, Damien; Piel, Clément; Defossez, Marc; Escape, Christophe; Devidal, Sébastien; Didier, Philippe; Bahn, Michael; Volaire, Florence; Augusti, Angela; Soussana, Jean-François; Picon-Cochard, Catherine

    2013-04-01

    Extreme climatic events are expected to be more frequent and intense in a few decades, but they will also occur in a climatic context different from the current one. In the Montpellier Ecotron, we studied the response of intact grassland monoliths (1m², 60 cm deep) sampled in an upland grassland of the French Massif Central. The first year the grasslands were acclimated to the average climatic conditions of the years around 2050 (+ 4 °C and - 56 mm for summer precipitations). The second year, the same climate was maintained but in half of the experimental units we imposed a summer drought and heat wave (50 % reduction of precipitations for a month and then 100 % precipitation reduction combined with a 3,4 °C increase in temperature for two weeks). A CO2 treatment (520 vs 380 µmol/mol) was crossed with the climatic treatment. Net CO2 fluxes were measured continuously during the second year of the experiment. The extreme climatic event induced a total senescence of the canopy whatever the CO2 treatment. The interactive effect of elevated CO2 with the drought treatment was significant at the onset of the drought and particularly large in the fall after the recovery period, with a net photosynthesis twice as high in the (extreme climate+ CO2) treatment compared to the control. Integrated over the year, elevated CO2 totally buffered the impact of the extreme climatic event on net CO2 exchanges. These results are discussed together with the evapotranspiration and soil humidity data.

  15. Methane Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Methane (CH4) flux is the net rate of methane exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS LandCarbon project...

  16. Net sea–air CO2 flux uncertainties in the Bay of Biscay based on the choice of wind speed products and gas transfer parameterizations

    Directory of Open Access Journals (Sweden)

    P. Otero

    2013-05-01

    Full Text Available The estimation of sea–air CO2 fluxes is largely dependent on wind speed through the gas transfer velocity parameterization. In this paper, we quantify uncertainties in the estimation of the CO2 uptake in the Bay of Biscay resulting from the use of different sources of wind speed such as three different global reanalysis meteorological models (NCEP/NCAR 1, NCEP/DOE 2 and ERA-Interim, one high-resolution regional forecast model (HIRLAM-AEMet, winds derived under the Cross-Calibrated Multi-Platform (CCMP project, and QuikSCAT winds in combination with some of the most widely used gas transfer velocity parameterizations. Results show that net CO2 flux estimations during an entire seasonal cycle (September 2002–September 2003 may vary by a factor of ~ 3 depending on the selected wind speed product and the gas exchange parameterization, with the highest impact due to the last one. The comparison of satellite- and model-derived winds with observations at buoys advises against the systematic overestimation of NCEP-2 and the underestimation of NCEP-1. In the coastal region, the presence of land and the time resolution are the main constraints of QuikSCAT, which turns CCMP and ERA-Interim in the preferred options.

  17. A Search for Periodicities in the $^8$B Solar Neutrino Flux Measured by the Sudbury Neutrino Observatory

    CERN Document Server

    Aharmim, B; Anthony, A E; Beier, E W; Bellerive, A; Bergevin, M; Biller, S D; Boulay, M G; Bowler, M G; Chan, Y D; Chen, M; Chen, X; Cleveland, B T; Costin, T; Cox, G A; Currat, C A; Dai, X; Deng, H; Detwiler, J; Doe, P J; Dosanjh, R S; Doucas, G; Duba, C A; Duncan, F A; Dunford, M; Dunmore, J A; Earle, E D; Elliott, S R; Evans, H C; Ewan, G T; Farine, J; Fergani, H; Fleurot, F; Formaggio, J A; Frati, W; Fulsom, B G; Gagnon, N; Goon, J T M; Graham, K; Hahn, R L; Hallin, A L; Hallman, E D; Handler, W B; Hargrove, C K; Harvey, P J; Hazama, R; Heeger, K M; Heelan, L; Heintzelman, W J; Heise, J; Helmer, R L; Hemingway, R J; Hime, A; Howe, M A; Huang, M; Inrig, E; Jagam, P; Jelley, N A; Klein, J R; Kormos, L L; Kos, M S; Krüger, A; Kraus, C V; Krauss, C B; Krumins, A V; Kutter, T; Kyba, C C M; Labranche, H; Lange, R; Law, J; Lawson, I T; Lesko, K T; Leslie, J R; Levine, I; Loach, J C; Luoma, S; MacLellan, R; Majerus, S; Maneira, J; Marino, A D; McCauley, N; McDonald, A B; McGee, S; Miin, C; Miknaitis, K K S; Nickel, B G; Noble, A J; Norman, E B; Oblath, N S; Okada, C E; O'Keeffe, H M; Ollerhead, R W; Orebi-Gann, G D; Orrell, J L; Oser, S M; Ouvarova, T; Peeters, S J M; Poon, A W P; Pun, C S J; Rielage, K; Robertson, B C; Robertson, R G H; Rollin, E; Rosendahl, S S E; Schwendener, M H; Seibert, S R; Simard, O; Simpson, J J; Sims, C J; Sinclair, D; Sinclair, L; Skensved, P; Smith, M W E; Stokstad, R G; Stonehill, L C; Tafirout, R; Takeuchi, Y; Tesic, G; Thomson, M; Tsang, K V; Tsui, T; Van Berg, R; Virtue, C J; Wall, B L; Waller, D; Waltham, C E; Wan Chan Tseung, H; Wark, D L; Wendland, J; West, N; Wilkerson, J F; Wilson, J R; Wouters, J M; Yeh, M; Zuber, K

    2005-01-01

    A search has been made for sinusoidal periodic variations in the $^8$B solar neutrino flux using data collected by the Sudbury Neutrino Observatory over a 4-year time interval. The variation at a period of one year is consistent with modulation of the $^8$B neutrino flux by the Earth's orbital eccentricity. No significant sinusoidal periodicities are found with periods between 1 day and 10 years with either an unbinned maximum likelihood analysis or a Lomb-Scargle periodogram analysis. The data are inconsistent with the hypothesis that the results of the recent analysis by Sturrock et al., based on elastic scattering events in Super-Kamiokande, can be attributed to a 7% sinusoidal modulation of the total $^8$B neutrino flux.

  18. Long-term Measurements of Solar Proton Fluxes (1963-present) and the Subsequent Impact on Stratospheric Constituents

    Science.gov (United States)

    Jackman, Charles H.; Fleming, Eric L.

    2005-01-01

    The fluxes of solar protons have been measured by satellites for over forty years (1963-present). Eight Interplanetary Monitoring Platform (IMP) satellites measured solar proton fluxes from 1963-1993 and five NOAA Geostationary Operational Environmental Satellites (GOES) were used for the period 1994present. These high energy solar protons precipitate on the Earth's polar atmosphere sporadically, especially during solar proton events (SPEs), which typically last a few days. Solar protons with energies greater than 30 MeV are capable of reaching the stratosphere and causing increases in odd hydrogen (HOx) and odd nitrogen (NOy) constituents at polar latitudes (greater than 60 degrees geomagnetic). The enhanced HOx leads to short-lived ozone depletion (-days) due to the short lifetime of HOx constituents. The enhanced NOy leads to long-lived ozone changes because of the long lifetime of the NOy family in the stratosphere. Several very large SPEs (August 1972, August and October 1989, July and November 2000, September and November 2001, and October 2003) over the 1963-2004 time period were simulated in the GSFC two-dimensional chemistry and transport model and were predicted to cause significant polar upper stratospheric ozone depletion greater than 10%, which lasted for several weeks past the events. Several satellite instruments (BUV, SBUV, SBW/2, SAGE II, HALOE, etc.) have shown constituent changes as a result of SPEs. Long-term (greater than 40 year) model simulations of the influence of the solar protons and satellite measurements during and after some of the very large SPEs will be shown.

  19. Relation of net portal flux of nitrogen compounds with dietary characteristics in ruminants: a meta-analysis approach.

    Science.gov (United States)

    Martineau, R; Sauvant, D; Ouellet, D R; Côrtes, C; Vernet, J; Ortigues-Marty, I; Lapierre, H

    2011-06-01

    Decrease of N intake (NI) with the aim of increasing efficiency of N utilization and decreasing the negative environmental effects of animal production requires assessment of the forms in which N is absorbed. A meta-analysis was conducted on 68 publications (90 experiments and 215 treatments) to study the effect of NI on net portal appearance (NPA) of nitrogenous nutrients [amino acids (AA), ammonia, and urea] in ruminants. In addition, the effect of several dietary energy and protein factors on this relationship was investigated. These factors were: dry matter intake; proportion of concentrate; diet concentrations and intakes of nonfiber carbohydrates and neutral detergent fiber (NDF); diet concentrations of total digestible nutrients (TDN) and crude protein; rumen-degradable protein and rumen-undegradable protein, as percent dry matter or percent crude protein. The effect of species and physiological stage was also investigated. Within-experiment analyses revealed that the NPA of AA-N and ammonia-N increased linearly, whereas the NPA of urea-N decreased (or recycling of urea-N increased) linearly with NI. Besides NI, many significant covariates could be introduced in each NPA model. However, only TDN and neutral detergent fiber intake (NDFi) were common significant covariates of NI in each NPA model. In this database, ruminants converted 60% of incremental NI into NPA of AA-N with no species effect on that slope. However, at similar NI, TDN, and NDFi, sheep absorbed more AA-N than did cattle and dairy cows. On the other hand, species tended to affect the slope of the relationship between NPA of ammonia-N and NI, which varied from 0.19 for the sheep to 0.38 for dairy cows. On average, the equivalent of 11% of incremental NI was recycled as urea-N to the gut through the portal-drained viscera, which excludes salivary contribution, and no species difference was detected. Overall, at similar TDN and NDFi, sheep and cattle increased their NPA of AA-N relative to NI

  20. Combined effects of ULF, VLF, and EMIC Waves, Substorms, and Solar Wind Parameters on Relativistic Electron Flux: Multiple Regression Analysis

    Science.gov (United States)

    Simms, L. E.; Engebretson, M. J.; Rodger, C. J.; Gjerloev, J. W.; Lessard, M.; Clilverd, M. A.; Pilipenko, V.; Reeves, G. D.

    2016-12-01

    Relativistic electron flux may be influenced by energy inputs from the solar wind (velocity, number density, and IMF Bz), substorm activity, source and seed electron populations (tens of keV and hundreds of keV, respectively), as well as by the ULF, VLF, and EMIC waves triggered by these factors. As all these variables are intercorrelated, we use multiple regression analyses to determine which are most influential when other factors are controlled. For the years 2005-2011, we use daily averages of LANL geostationary orbit electron data (three high energy channels, as well as source and seed electrons), number of substorms per day from the SUPERMAG substorm list, a ULF index from ground magnetometers, lower band whistler mode chorus power (VLF) observed by the DEMETER satellite, and EMIC (support several hypotheses. ULF and VLF waves enhance the 1.8-3.5 MeV electron flux but their effect falls off (or becomes negative) on higher energy fluxes (3.5-6.0 and 6.0-7.8 MeV). EMIC waves reduce high energy electron flux mainly in the highest energy channel (6.0-7.8 MeV); their effect on the lower 1.8-3.5 MeV channel is minimal. A higher number of substorms in a day also enhance relativistic electron flux, with more impact at higher energy channels. We explore the relations between these parameters using path analysis to determine the mechanisms driving wave power which subsequently impact flux levels. We also assess the predictive ability of these models in forecasting flux.

  1. Magnetic Flux Rope Shredding By a Hyperbolic Flux Tube: The Detrimental Effects of Magnetic Topology on Solar Eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Chintzoglou, Georgios [Lockheed Martin Solar and Astrophysics Laboratory, 3176 Porter Drive, Palo Alto, CA 94304 (United States); Vourlidas, Angelos [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Savcheva, Antonia; Tassev, Svetlin [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Beltran, Samuel Tun; Stenborg, Guillermo, E-mail: gchintzo@lmsal.com [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2017-07-10

    We present the analysis of an unusual failed eruption captured in high cadence and in many wavelengths during the observing campaign in support of the Very high Angular resolution Ultraviolet Telescope ( VAULT2.0 ) sounding rocket launch. The refurbished VAULT2.0 is a Ly α ( λ 1216 Å) spectroheliograph launched on 2014 September 30. The campaign targeted active region NOAA AR 12172 and was closely coordinated with the Hinode and IRIS missions and several ground-based observatories (NSO/IBIS, SOLIS, and BBSO). A filament eruption accompanied by a low-level flaring event (at the GOES C-class level) occurred around the VAULT2.0 launch. No coronal mass ejection was observed. The eruption and its source region, however, were recorded by the campaign instruments in many atmospheric heights ranging from the photosphere to the corona in high cadence and spatial resolution. This is a rare occasion that enabled us to perform a comprehensive investigation on a failed eruption. We find that a rising Magnetic Flux Rope (MFR)-like structure was destroyed during its interaction with the ambient magnetic field, creating downflows of cool plasma and diffuse hot coronal structures reminiscent of “cusps.” We employ magnetofrictional simulations to show that the magnetic topology of the ambient field is responsible for the destruction of the MFR. Our unique observations suggest that the magnetic topology of the corona is a key ingredient for a successful eruption.

  2. Using the Synergy Between GERB/SEVIRI and Micrometeorological Data to Study the Relationship Between Surface Net Radiation and Soil Heat Flux at Local and Regional Scales

    Science.gov (United States)

    Ferreira, A. G.; Velázquez Blázquez, A.; Soria, E.; Lopez-Baeza, E.

    2009-04-01

    The surface energy exchange between the land surface and the atmosphere can be described by the energy balance equation Rn - H - LE - G = 0, where Rn represents net radiation, H the sensible heat flux, LE, the latent heat flux and G the soil heat flux. In this work the relationship between Rn and G is studied over vineyard crops, a relative sparse vegetation cover crop where, according to the literature, it is expected that G consumes a significant proportion of Rn. In order to study this relationship at local and regional scales, micrometeorological observations and METEOSAT Second Generation (MSG) satellite data have been used. MSG through the GERB (Geostationary Earth Radiation Budget) and the SEVIRI (Spinning Enhanced Visible and Infrared Imager) sensors can provide estimates of net radiation and required land surface temperature (LST) information with a frequency of 15 min intervals. The necessary micrometeorological parameters, to compare with satellite data, were collected during the full vine growing season of 2007 (May to September) in a field experiment carried out at the Valencia Anchor Station (VAS) site area. The VAS is a robust reference meteorological station which is successfully used preferentially for validation of low spatial resolution satellite data and products. It is located on the natural region of the Utiel-Requena Plateau, at about 80 km west from the city of Valencia, Spain, and represents a reasonable homogeneous area of about 50 km x 50 km dedicated primarily to growing vines. The methodology utilized to study the relationship between Rn and G at local and regional scales, was that proposed by Santanello and Friedel (2002), where surface temperature can be obtained from SEVIRI that provides estimates of LST with unprecedented frequency of 15 min intervals with a spatial resolution of 3.1 km, thus totally covering its diurnal course. The preliminary results show that: 1- the correlation between the ground measurements and SEVIRI LST is

  3. Clustering of Emerging Flux

    Science.gov (United States)

    Ruzmaikin, A.

    1997-01-01

    Observations show that newly emerging flux tends to appear on the Solar surface at sites where there is flux already. This results in clustering of solar activity. Standard dynamo theories do not predict this effect.

  4. Willingness to pay for small solar powered bed net fans: results of a Becker-DeGroot-Marschak auction in Ghana.

    Science.gov (United States)

    Yukich, Joshua O; Briët, Olivier J T; Ahorlu, Collins K; Nardini, Peter; Keating, Joseph

    2017-08-07

    Long-lasting insecticidal nets (LLINs) are one of the main interventions recommended by the World Health Organization for malaria vector control. LLINs are ineffective if they are not being used. Subsequent to the completion of a cluster randomized cross over trial conducted in rural Greater Accra where participants were provided with the 'Bɔkɔɔ System'-a set of solar powered net fan and light consoles with a solar panel and battery-or alternative household water filters, all trial participants were invited to participate in a Becker-DeGroot-Marschak auction to determine the mean willingness to pay (WTP) for the fan and light consoles and to estimate the demand curve for the units. Results demonstraed a mean WTP of approximately 55 Cedis (~13 USD). Demand results suggested that at a price which would support full manufacturing cost recovery, a majority of households in the area would be willing to purchase at least one such unit.

  5. Optical Calibration Of The Sudbury Neutrino Observatory And Determination Of The Boron-8 Solar Neutrino Flux In The Salt Phase

    CERN Document Server

    Grant, D R

    2004-01-01

    An improved measurement of the 8B solar neutrino flux has been made at the Sudbury Neutrino Observatory (SNO). This measurement has an increased sensitivity to the neutral current reaction. This is due to an enhanced neutron capture efficiency, accomplished by adding salt, NaCl, to the heavy water in the detector. The data set analyzed in the salt phase consists of approximately 254 days of neutrino data. The data set has been analyzed using independently developed probability density functions (PDFs) in an extended maximum likelihood calculation. The final 8B model-constrained results of this analysis are given by the fluxes (in units of 106 neutrinos/(cm2s)): •FSunCC=1 .69±0.07stat +0.07- 0.08 syst •FSunNC=4.91±0.2 3stat +0.32-0.27 syst •FSumES=2.11 +0.29- 0.27 stat+0.13 -0.19syst These fluxes give a CC/NC ratio of 0.344 ± 0.021(stat) +0.07- 0.08 syst . The results clearly demonstrate that solar neutrinos are oscillating from one flavor to a...

  6. THE BEHAVIOR OF TRANSVERSE WAVES IN NONUNIFORM SOLAR FLUX TUBES. I. COMPARISON OF IDEAL AND RESISTIVE RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramón [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Goossens, Marcel, E-mail: roberto.soler@uib.es [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)

    2013-11-10

    Magnetohydrodynamic (MHD) waves are ubiquitously observed in the solar atmosphere. Kink waves are a type of transverse MHD waves in magnetic flux tubes that are damped due to resonant absorption. The theoretical study of kink MHD waves in solar flux tubes is usually based on the simplification that the transverse variation of density is confined to a nonuniform layer much thinner than the radius of the tube, i.e., the so-called thin boundary approximation. Here, we develop a general analytic method to compute the dispersion relation and the eigenfunctions of ideal MHD waves in pressureless flux tubes with transversely nonuniform layers of arbitrary thickness. Results for kink waves are produced and compared with fully numerical resistive MHD eigenvalue computations in the limit of small resistivity. We find that the frequency and resonant damping rate are the same in both ideal and resistive cases. The actual results for thick nonuniform layers deviate from the behavior predicted in the thin boundary approximation and strongly depend on the shape of the nonuniform layer. The eigenfunctions in ideal MHD are very different from those in resistive MHD. The ideal eigenfunctions display a global character regardless of the thickness of the nonuniform layer, while the resistive eigenfunctions are localized around the resonance and are indistinguishable from those of ordinary resistive Alfvén modes. Consequently, the spatial distribution of wave energy in the ideal and resistive cases is dramatically different. This poses a fundamental theoretical problem with clear observational consequences.

  7. Physics of erupting solar flux ropes: Coronal mass ejections (CMEs)—Recent advances in theory and observation

    Science.gov (United States)

    Chen, James

    2017-09-01

    Solar eruptions, observed as flares and coronal mass ejections (CMEs), are the most energetic visible plasma phenomena in the solar system. CMEs are the central component of solar eruptions and are detected as coherent magnetized plasma structures expanding in the solar wind (SW). If they reach the Earth, their magnetic fields can drive strong disturbances in the ionosphere, causing deleterious effects on terrestrial technological systems. The scientific and practical importance of CMEs has led to numerous satellite missions observing the Sun and SW. This has culminated in the ability to continuously observe CMEs expanding from the Sun to 1 AU, where the magnetic fields and plasma parameters of the evolved structures ("ejecta") can be measured in situ. Until recently, the physical mechanisms responsible for eruptions were major unanswered questions in solar and by extension stellar physics. New observations of CME dynamics and associated eruptive phenomena are now providing more stringent constraints on models, and quantitative theory-data comparisons are helping to establish the correct mechanism of solar eruptions, particularly the driving force of CMEs and the evolution of their magnetic fields in three dimensions. Recent work has demonstrated that theoretical results can simultaneously replicate the observed CME position-time data, temporal profiles of associated solar flare soft X-ray emissions, and the magnetic field and plasma parameters of CME ejecta measured at 1 AU. Thus, a new theoretical framework with testable predictions is emerging to model eruptions and the coupling of CME ejecta to geomagnetic disturbances. The key physics in CME dynamics is the Lorentz hoop force acting on toroidal "flux ropes," scalable from tokamaks and similar laboratory plasma structures. The present paper reviews the latest advances in observational and theoretical understanding of CMEs with the emphasis on quantitative comparisons of theory and observation.

  8. An Early Diagnostics of the Geoeffectiveness of Solar Eruptions from Photospheric Magnetic Flux Observations: The Transition from SOHO to SDO

    Science.gov (United States)

    Chertok, I. M.; Grechnev, V. V.; Abunin, A. A.

    2017-04-01

    In our previous articles (Chertok et al. in Solar Phys. 282, 175, 2013; Chertok et al. in Solar Phys. 290, 627, 2015), we presented a preliminary tool for the early diagnostics of the geoeffectiveness of solar eruptions based on the estimate of the total unsigned line-of-sight photospheric magnetic flux in accompanying extreme ultraviolet (EUV) arcades and dimmings. This tool was based on the analysis of eruptions observed during 1996 - 2005 with the Extreme-ultraviolet Imaging Telescope (EIT) and the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). Empirical relationships were obtained to estimate the probable importance of upcoming space weather disturbances caused by an eruption, which just occurred, without data on the associated coronal mass ejections. In particular, it was possible to estimate the intensity of a non-recurrent geomagnetic storm (GMS) and Forbush decrease (FD), as well as their onset and peak times. After 2010 - 2011, data on solar eruptions are obtained with the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We use relatively short intervals of overlapping EIT-AIA and MDI-HMI detailed observations, and additionally, a number of large eruptions over the next five years with the 12-hour cadence EIT images to adapt the SOHO diagnostic tool to SDO data. We show that the adopted brightness thresholds select practically the same areas of arcades and dimmings from the EIT 195 Å and AIA 193 Å image, with a cross-calibration factor of 3.6 - 5.8 (5.0 - 8.2) for the AIA exposure time of 2.0 s (2.9 s). We also find that for the same photospheric areas, the MDI line-of-sight magnetic flux systematically exceeds the HMI flux by a factor of 1.4. Based on these results, the empirical diagnostic relationships obtained from SOHO data are adjusted to SDO instruments. Examples of a post-diagnostics based on SDO data are presented. As before, the

  9. Open solar flux estimates from near-Earth measurements of the interplanetary magnetic field: comparison of the first two perihelion passes of the Ulysses spacecraft

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2004-04-01

    Full Text Available Results from all phases of the orbits of the Ulysses spacecraft have shown that the magnitude of the radial component of the heliospheric field is approximately independent of heliographic latitude. This result allows the use of near-Earth observations to compute the total open flux of the Sun. For example, using satellite observations of the interplanetary magnetic field, the average open solar flux was shown to have risen by 29% between 1963 and 1987 and using the aa geomagnetic index it was found to have doubled during the 20th century. It is therefore important to assess fully the accuracy of the result and to check that it applies to all phases of the solar cycle. The first perihelion pass of the Ulysses spacecraft was close to sunspot minimum, and recent data from the second perihelion pass show that the result also holds at solar maximum. The high level of correlation between the open flux derived from the various methods strongly supports the Ulysses discovery that the radial field component is independent of latitude. We show here that the errors introduced into open solar flux estimates by assuming that the heliospheric field's radial component is independent of latitude are similar for the two passes and are of order 25% for daily values, falling to 5% for averaging timescales of 27 days or greater. We compare here the results of four methods for estimating the open solar flux with results from the first and second perehelion passes by Ulysses. We find that the errors are lowest (1–5% for averages over the entire perehelion passes lasting near 320 days, for near-Earth methods, based on either interplanetary magnetic field observations or the aa geomagnetic activity index. The corresponding errors for the Solanki et al. (2000 model are of the order of 9–15% and for the PFSS method, based on solar magnetograms, are of the order of 13–47%. The model of Solanki et al. is based on the continuity equation of open flux, and uses the

  10. Optimization of permeate flux produced by solar energy driven membrane distillation process using central composite design approach.

    Science.gov (United States)

    Bouguecha, Salah T; Boubakri, Ali; Aly, Samir E; Al-Beirutty, Mohammad H; Hamdi, Mohamed M

    2016-01-01

    Membrane distillation (MD) is considered as a relatively high-energy requirement. To overcome this drawback, it is recommended to couple the MD process with solar energy as the renewable energy source in order to provide heat energy required to optimize its performance to produce permeate flux. In the present work, an original solar energy driven direct contact membrane distillation (DCMD) pilot plant was built and tested under actual weather conditions at Jeddah, KSA, in order to model and optimize permeate flux. The dependency of permeate flux on various operating parameters such as feed temperature (46.6-63.4°C), permeate temperature (6.6-23.4°C), feed flow rate (199-451L/h) and permeate flow rate (199-451L/h) was studied by response surface methodology based on central composite design approach. The analysis of variance (ANOVA) confirmed that all independent variables had significant influence on the model (where P-value <0.05). The high coefficient of determination (R(2) = 0.9644 and R(adj)(2) = 0.9261) obtained by ANOVA demonstrated good correlation between experimental and predicted values of the response. The optimized conditions, determined using desirability function, were T(f) = 63.4°C, Tp = 6.6°C, Q(f) = 451L/h and Q(p) = 451L/h. Under these conditions, the maximum permeate flux of 6.122 kg/m(2).h was achieved, which was close to the predicted value of 6.398 kg/m(2).h.

  11. Oscillations in the open solar magnetic flux with a period of 1.68 years: imprint on galactic cosmic rays and implications for heliospheric shielding

    Directory of Open Access Journals (Sweden)

    A. Rouillard

    2004-12-01

    Full Text Available An understanding of how the heliosphere modulates galactic cosmic ray (GCR fluxes and spectra is important, not only for studies of their origin, acceleration and propagation in our galaxy, but also for predicting their effects (on technology and on the Earth's environment and organisms and for interpreting abundances of cosmogenic isotopes in meteorites and terrestrial reservoirs. In contrast to the early interplanetary measurements, there is growing evidence for a dominant role in GCR shielding of the total open magnetic flux, which emerges from the solar atmosphere and enters the heliosphere. In this paper, we relate a strong 1.68-year oscillation in GCR fluxes to a corresponding oscillation in the open solar magnetic flux and infer cosmic-ray propagation paths confirming the predictions of theories in which drift is important in modulating the cosmic ray flux. Key words. Interplanetary physics (Cosmic rays, Interplanetary magnetic fields

  12. Quantifying solar flux and geomagnetic main field influence on the equatorial ionospheric current system at the geomagnetic observatory Huancayo

    Science.gov (United States)

    Matzka, Jürgen; Siddiqui, Tarique A.; Lilienkamp, Henning; Stolle, Claudia; Veliz, Oscar

    2017-10-01

    In order to analyse the sensitivity of the equatorial ionospheric current system, i.e. the solar quiet current system and the equatorial electrojet, to solar cycle variations and to the secular variation of the geomagnetic main field, we have analysed 51 years (1935-1985) of geomagnetic observatory data from Huancayo, Peru. This period is ideal to analyse the influence of the main field strength on the amplitude of the quiet daily variation, since the main field decreases significantly from 1935 to 1985, while the distance of the magnetic equator to the observatory remains stable. To this end, we digitised some 19 years of hourly mean values of the horizontal component (H), which have not been available digitally at the World Data Centres. Then, the sensitivity of the amplitude ΔH of the quiet daily variation to both solar cycle variations (in terms of sunspot numbers and solar flux F10.7) and changes of the geomagnetic main field strength (due to secular variation) was determined. We confirm an increase of ΔH for the decreasing main field in this period, as expected from physics based models (Cnossen, 2016), but with a somewhat smaller rate of 4.4% (5.8% considering one standard error) compared with 6.9% predicted by the physics based model.

  13. Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24

    Science.gov (United States)

    Martucci, M.; Munini, R.; Boezio, M.; Di Felice, V.; Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; De Santis, C.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Marcelli, N.; Mayorov, A. G.; Menn, W.; Mergè, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Osteria, G.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.; Potgieter, M. S.; Raath, J. L.

    2018-02-01

    Precise measurements of the time-dependent intensity of the low-energy (physical phenomena. The minimum phase between solar cycles 23 and 24 was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this Letter, we present proton differential spectra measured from 2010 January to 2014 February by the PAMELA experiment. For the first time the GCR proton intensity was studied over a wide energy range (0.08–50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.

  14. MHD Forces in Quasi-Static Evolution, Catastrophe, and ``Failed'' Eruption of Solar Flux Ropes

    Science.gov (United States)

    Chen, James

    2017-08-01

    This paper presents the first unified theoretical model of flux rope dynamics---a single set of flux-rope equations in ideal MHD---to describe as one dynamical process the quasi-static evolution, catastrophic transition to eruption, cessation (``failure'') of eruption, and the post-eruption quasi-equilibria. The model is defined by the major radial {\\it and} minor radial equations of motion including pressure. The initial equilibrium is a flux rope in a background plasma with pressure $p_c(Z)$ and an overlying magnetic field $B_c(Z)$. The flux rope is initially force-free, but theevolution is not required to be force- free. A single quasi-static control parameter, the rate of increase in poloidal flux, is used for the entire process. As this parameter is slowly increased, the flux rope rises, following a sequence of quasi-static equilibria. As the apex of the flux rope rises past a critical height $Z_{crt}$, it expands on a dynamical (Alfvénic) timescale. The eruption rapidly ceases, as the stored magnetic energy of eruption is exhausted, and a new equilibrium is established at height $Z_1 > Z_{crt}$. The calculated velocity profile resembles the observed velocity profiles in ``failed'' eruptions including a damped oscillation. In the post-eruption equilibria, the outward hoop force is balanced by the tension of the toroidal self magnetic field and pressure gradient force. Thus, the flux rope does not evolve in a force-free manner. The flux rope may also expand without reaching a new equilibrium, provided a sufficient amount of poloidal flux is injected on the timescale of eruption. This scenario results in a full CME eruption. It is shown that the minor radial expansion critically couples the evolution of the toroidal self-field and pressure gradient force. No parameter regime is found in which the commonly used simplifications---near-equilibrium minor radial expansion, force-free expansion, and constant aspect ratio $R/a$ (e.g., the torus instability equation

  15. Activity-dependent branching ratios in stocks, solar x-ray flux, and the Bak-Tang-Wiesenfeld sandpile model

    Science.gov (United States)

    Martin, Elliot; Shreim, Amer; Paczuski, Maya

    2010-01-01

    We define an activity-dependent branching ratio that allows comparison of different time series Xt . The branching ratio bx is defined as bx=E[ξx/x] . The random variable ξx is the value of the next signal given that the previous one is equal to x , so ξx={Xt+1∣Xt=x} . If bx>1 , the process is on average supercritical when the signal is equal to x , while if bxefficient market hypothesis.” For stock volumes, solar x-ray flux intensities, and the Bak-Tang-Wiesenfeld (BTW) sandpile model, bx is supercritical for small values of activity and subcritical for the largest ones, indicating a tendency to return to a typical value. For stock volumes this tendency has an approximate power-law behavior. For solar x-ray flux and the BTW model, there is a broad regime of activity where bx≃1 , which we interpret as an indicator of critical behavior. This is true despite different underlying probability distributions for Xt and for ξx . For the BTW model the distribution of ξx is Gaussian, for x sufficiently larger than 1, and its variance grows linearly with x . Hence, the activity in the BTW model obeys a central limit theorem when sampling over past histories. The broad region of activity where bx is close to one disappears once bulk dissipation is introduced in the BTW model—supporting our hypothesis that it is an indicator of criticality.

  16. Periodicity of variations in galactic cosmic ray fluxes and solar activity parameters near 20th cycle minimum

    Science.gov (United States)

    Gorchakov, Y. V.; Ignatyev, P. P.; Okhlopkov, V. P.; Shvidkovskaya, T. Y.

    1985-05-01

    An autocorrelation analysis of Wolf numbers clearly reveals a two year periodicity in solar activity during the period 1970-1975. Then, up to 1978, no such periodicity was detected and there was no correlation with earlier data (probably attributable to the low level of solar activity and the onset of a new solar activity cycle). Against this background, a correlation analysis was made of the mean monthly fluxes of cosmic rays measured aboard spacecraft, in the stratosphere (at Murmansk) and at the Earth's surface (Deep River), as well as Wolf numbers. The objective was to find a periodicity on the basis of the correlation dependences of two year intervals of data on cosmic rays and Wolf numbers. An approximately two year periodicity in the modulation of cosmic rays was discovered. The manifestation of this periodicity is different for different measurement periods and different energies of galactic cosmic rays. A table gives data on the maxima of the correlation coefficients, the lag relative to Wolf numbers and the extent of the modulation region on the assumption of a plasma velocity of 300 km/sec. The tabulated data characterize the dependence of the extent of the modulation region on the energy of GCR particles.

  17. A theoretical framework for the net land-to-atmosphere CO2 flux and its implications in the definition of "emissions from land-use change"

    OpenAIRE

    T. Gasser; Ciais, P

    2013-01-01

    We develop a theoretical framework and analysis of the net land-to-atmosphere CO2 flux in order to discuss possible definitions of "emissions from land-use change". The terrestrial biosphere is affected by two perturbations: the perturbation of the global carbon-climate-nitrogen system (CCN) with elevated atmospheric CO2, climate change and nitrogen deposition; and the land-use change perturbation (LUC). Here, we progressively establish mathematical definitions of four gener...

  18. A theoretical framework for the net land-to-atmosphere CO2 flux and its implications in the definition of "emissions from land-use change"

    OpenAIRE

    T. Gasser; Ciais, P

    2013-01-01

    We develop a theoretical framework and analysis of the net land-to-atmosphere CO2 flux in order to discuss possible definitions of "emissions from land-use change". The terrestrial biosphere is affected by two perturbations: the perturbation of the global Carbon-Climate-Nitrogen system (CCN) with elevated atmospheric CO2, climate change and nitrogen deposition; and the Land-Use Change perturbation (LUC). Here, we progressively establish mathematical definitions of four generic components of t...

  19. Computation of Solar Radiative Fluxes by 1D and 3D Methods Using Cloudy Atmospheres Inferred from A-train Satellite Data

    Science.gov (United States)

    Barker, Howard W.; Kato, Serji; Wehr, T.

    2012-01-01

    The main point of this study was to use realistic representations of cloudy atmospheres to assess errors in solar flux estimates associated with 1D radiative transfer models. A scene construction algorithm, developed for the EarthCARE satellite mission, was applied to CloudSat, CALIPSO, and MODIS satellite data thus producing 3D cloudy atmospheres measuring 60 km wide by 13,000 km long at 1 km grid-spacing. Broadband solar fluxes and radiances for each (1 km)2 column where then produced by a Monte Carlo photon transfer model run in both full 3D and independent column approximation mode (i.e., a 1D model).

  20. Response of the radiation belt electron flux to the solar wind velocity: Parameterization by radial distance and energy

    Science.gov (United States)

    Vassiliadis, D.

    2008-11-01

    The solar wind velocity is the primary driver of the electron flux variability in Earth's radiation belts. The response of the logarithmic flux ("log-flux") to this driver has been determined at the geosynchronous orbit and at a fixed energy [Baker, D.N., McPherron, R.L., Cayton, T.E., Klebesadel, R.W., 1990. Linear prediction filter analysis of relativistic electron properties at 6.6 RE. Journal of Geophysical Research 95(A9), 15,133-15,140) and as a function of L shell and fixed energy [Vassiliadis, D., Klimas, A.J., Kanekal, S.G., Baker, D.N., Weigel, R.S., 2002. Long-term average, solar-cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed. Journal of Geophysical Research 107, doi:10.1029/2001JA000506). In this paper we generalize the response model as a function of particle energy (0.8-6.4 MeV) using POLAR HIST measurements. All three response peaks identified earlier figure prominently in the high-altitude POLAR measurements. The positive response around the geosynchronous orbit is peak P1 ([tau]=2±1 d; L=5.8±0.5; E=0.8-6.4 MeV), associated with high-speed, low-density streams and the ULF wave activity they produce. Deeper in the magnetosphere, the response is dominated by a positive peak P0 (0±1 d; 2.9±0.5RE; 0.8-1.1 MeV), of a shorter duration and producing lower-energy electrons. The P0 response occurs during the passage of geoeffective structures containing high IMF and high-density parts, such as ICMEs and other mass ejecta. Finally, the negative peak V1 (0±0.5 d; 5.7±0.5RE; 0.8-6.4 MeV) is associated with the "Dst effect" or the quasiadiabatic transport produced by ring-current intensifications. As energies increase, the P1 and V1 peaks appear at lower L, while the Dst effect becomes more pronounced in the region L1.6 MeV because of low statistics, although it is evident in individual events. The continuity of the response across radial and energy scales supports the earlier hypothesis that each of the three

  1. Solar flux variation of the electron temperature morning overshoot in the equatorial F region

    DEFF Research Database (Denmark)

    Stolle, Claudia; Liu, H.; Truhlik, V.

    2011-01-01

    Using 8 years of CHAMP satellite observations of the equatorial electron temperature, T-e, we investigate its behavior during the morning overshoot and at ionospheric altitudes below 450 km including its variation with solar activity. The morning T-e has a maximum at the dip equator and decreases...

  2. Changed Relation between Solar 10.7-cm Radio Flux and some ...

    Indian Academy of Sciences (India)

    From 1985 the total solar irradiance was observed by Earth Radiation Bud- get Satellite (EBRS). We use the NGDC TSI data set from combined observational data of several satellites which were collected in NASA archive data (National .... The polynomial model corresponds to the following equation of a second order.

  3. Solar Magnetic Flux Ropes Boris Filippov1,∗, Olesya Martsenyuk1 ...

    Indian Academy of Sciences (India)

    2015-01-09

    . Paletou, F., Aulanier, G. 2003, in Solar Polarization Workshop 3, edited by Trujillo Bueno, J.,. Sánchez Almeida, J., CS-236, Astron. Soc. Pac., San Francisco, p. 458. Pariat, E., Antiochos, S. K., DeVore, C. R. 2009, Astrophys.

  4. Measurement of the nue and Total 8B Solar Neutrino Fluxes with theSudbury Neutrino Observatory Phase I Data Set

    Energy Technology Data Exchange (ETDEWEB)

    Aharmim, B.; Ahmad, Q.R.; Ahmed, S.N.; Allen, R.C.; Andersen,T.C.; Anglin, J.D.; Buehler, G.; Barton, J.C.; Beier, E.W.; Bercovitch,M.; Bergevin, M.; Bigu, J.; Biller, S.D.; Black, R.A.; Blevis, I.; Boardman, R.J.; Boger, J.; Bonvin, E.; Boulay, M.G.; Bowler, M.G.; Bowles, T.J.; Brice, S.J.; Browne, M.C.; Bullard, T.V.; Burritt, T.H.; Cameron, J.; Chan, Y.D.; Chen, H.H.; Chen, M.; Chen, X.; Cleveland, B.T.; Cowan, J.H.M.; Cowen, D.F.; Cox, G.A.; Currat, C.A.; Dai, X.; Dalnoki-Veress, F.; Davidson, W.F.; Deng, H.; DiMarco, M.; Doe, P.J.; Doucas, G.; Dragowsky, M.R.; Duba, C.A.; Duncan, F.A.; Dunford, M.; Dunmore, J.A.; Earle, E.D.; Elliott, S.R.; Evans, H.C.; Ewan, G.T.; Farine, J.; Fergani, H.; Ferraris, A.P.; Fleurot, F.; Ford, R.J.; Formaggio, J.A.; Fowler, M.M.; Frame, K.; Frank, E.D.; Frati, W.; Gagnon,N.; Germani, J.V.; Gil, S.; Goldschmidt, A.; Goon, J.T.M.; Graham, K.; Grant, D.R.; Guillian, E.; Hahn, R.L.; Hallin, A.L.; Hallman, E.D.; Hamer, A.S.; Hamian, A.A.; Handler, W.B.; Haq, R.U.; Hargrove, C.K.; Harvey, P.J.; Hazama, R.; Heeger, K.M.; Heintzelman, W.J.; Heise, J.; Helmer, R.L.; Henning, R.; Hepburn, J.D.; Heron, H.; Hewett, J.; Hime,A.; Howard, C.; Howe, M.A.; Huang, M.; Hykawy, J.G.; Isaac, M.C.P.; Jagam, P.; Jamieson, B.; Jelley, N.A.; Jillings, C.; Jonkmans, G.; Kazkaz, K.; Keener, P.T.; Kirch, K.; Klein, J.R.; Knox, A.B.; Komar,R.J.; Kormos, L.L.; Kos, M.; Kouzes, R.; Krueger, A.; Kraus, C.; Krauss,C.B.; Kutter, T.; Kyba, C.C.M.; Labranche, H.; Lange, R.; Law, J.; Lawson, I.T.; Lay, M.; Lee, H.W.; Lesko, K.T.; Leslie, J.R.; Levine, I.; Loach, J.C.; Locke, W.; Luoma, S.; Lyon, J.; MacLellan, R.; Majerus, S.; Mak, H.B.; Maneira, J.; Marino, A.D.; Martin, R.; McCauley, N.; McDonald,A.B.; McDonald, D.S.; McFarlane, K.; McGee, S.; McGregor, G.; MeijerDrees, R.; Mes, H.; Mifflin, C.; Miknaitis, K.K.S.; Miller, M.L.; Milton,G.; Moffat, B.A.; Monreal, B.; Moorhead, M.; Morrissette, B.; Nally,C.W.; Neubauer, M.S.; et al.

    2007-02-01

    This article provides the complete description of resultsfrom the Phase I data set of the Sudbury Neutrino Observatory (SNO). ThePhase I data set is based on a 0.65 kt-year exposure of heavy water tothe solar 8B neutrino flux. Included here are details of the SNO physicsand detector model, evaluations of systematic uncertainties, andestimates of backgrounds. Also discussed are SNO's approach tostatistical extraction of the signals from the three neutrino reactions(charged current, neutral current, and elastic scattering) and theresults of a search for a day-night asymmetry in the ?e flux. Under theassumption that the 8B spectrum is undistorted, the measurements fromthis phase yield a solar ?e flux of ?(?e) =1.76+0.05?0.05(stat.)+0.09?0.09 (syst.) x 106 cm?2 s?1, and a non-?ecomponent ?(? mu) = 3.41+0.45?0.45(stat.)+0.48?0.45 (syst.) x 106 cm?2s?1. The sum of these components provides a total flux in excellentagreement with the predictions of Standard Solar Models. The day-nightasymmetry in the ?e flux is found to be Ae = 7.0 +- 4.9 (stat.)+1.3?1.2percent (sys.), when the asymmetry in the total flux is constrained to bezero.

  5. Saldo de radiação diurno em dosséis de batata como função da radiação solar global Daytime net radiation on potato canopies as a function of global solar radiation

    Directory of Open Access Journals (Sweden)

    Arno Bernardo Heldwein

    2012-03-01

    purposes of calculation, were performed daily sums of Rn and Rg. Through these, it was calculated the Rn/Rg ratio for each day. There was obtained a good relationship between changes in Rn and Rg. This relationship was confirmed in the regression analysis, obtaining models with high correlation coefficient, indicating precisely to estimate net radiation in potato canopies as a function of incident solar radiation (Rg, irrespective of season. The function general linear obtained with data from different years, growing seasons and genotypes was not sensitive to leaf area index, resulting in: Rg Rn = 0.6410 (R² = 0.976, that in the test showed RQME = 0.75 MJ m-2 dia-1. The diurnal energy flux density of net radiation can be estimated through using the flux density of global solar radiation measured in automatic stations with sufficient accuracy for modeling.

  6. Dilation of force-free magnetic flux tubes. [solar magnetic field profiles

    Science.gov (United States)

    Frankenthal, S.

    1977-01-01

    A general study is presented of the mapping functions which relate the magnetic-field profiles across a force-free rope in segments subjected to various external pressures. The results reveal that if the external pressure falls below a certain critical level (dependent on the flux-current relation which defines the tube), the magnetic profile consists of an invariant core sheathed in a layer permeated by an azimuthal magnetic field.

  7. TIME DEPENDENCE OF THE e{sup −} FLUX MEASURED BY PAMELA DURING THE 2006 JULY–2009 DECEMBER SOLAR MINIMUM

    Energy Technology Data Exchange (ETDEWEB)

    Adriani, O.; Bongi, M. [University of Florence, Department of Physics, I-50019 Sesto Fiorentino, Florence (Italy); Barbarino, G. C. [University of Naples “Federico II,” Department of Physics, I-80126 Naples (Italy); Bazilevskaya, G. A. [Lebedev Physical Institute, RU-119991, Moscow (Russian Federation); Bellotti, R.; Bruno, A. [University of Bari, Department of Physics, I-70126 Bari (Italy); Boezio, M.; Bonvicini, V.; Formato, V. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Bogomolov, E. A. [Ioffe Physical Technical Institute, RU-194021 St. Petersburg (Russian Federation); Bottai, S. [INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence (Italy); Cafagna, F. [INFN, Sezione di Bari, I-70126 Bari (Italy); Campana, D. [INFN, Sezione di Naples, I-80126 Naples (Italy); Carlson, P. [KTH, Department of Physics, and the Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691 Stockholm (Sweden); Casolino, M.; Santis, C. De [University of Rome “Tor Vergata,” Department of Physics, I-00133 Rome (Italy); Castellini, G. [IFAC, I-50019 Sesto Fiorentino, Florence (Italy); Donato, C. De; Simone, N. De; Felice, V. Di [INFN, Sezione di Rome “Tor Vergata,” I-00133 Rome (Italy); and others

    2015-09-10

    Precision measurements of the electron component of cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy not accessible from the study of cosmic-ray nuclear components due to their differing diffusion and energy-loss processes. However, when measured near Earth, the effects of propagation and modulation of Galactic cosmic rays in the heliosphere, particularly significant for energies up to at least 30 GeV, must be properly taken into account. In this paper the electron (e{sup −}) spectra measured by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics down to 70 MeV from 2006 July to 2009 December over six-month time intervals are presented. Fluxes are compared with a state-of-the-art three-dimensional model of solar modulation that reproduces the observations remarkably well.

  8. Geomagnetically trapped, albedo and solar energetic particles: Trajectory analysis and flux reconstruction with PAMELA

    Science.gov (United States)

    Bruno, A.; Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; Christian, E. C.; De Donato, C.; de Nolfo, G. A.; De Santis, C.; De Simone, N.; Di Felice, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergè, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Ryan, J. M.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stochaj, S.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.

    2017-08-01

    The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival.

  9. Downward Heat Penetration below Seasonal Thermocline and its Impact on Sea Surface Temperature Variation Affected by Net Heat Flux during Summer Season

    Science.gov (United States)

    Hosoda, S.; Nonaka, M.; Tomita, T.; Taguchi, B.; Tomita, H.; Iwasaka, N.

    2016-02-01

    Oceanic heat capacity of the upper layer is a key of the change in the sea surface temperature (SST) affecting air-sea heat exchange and of the temporal scale of SST variability. In the past, studies of SST variability associated with the air-sea heat exchange have mainly focused on the conditions during the winter, because wintertime deep mixed layer (ML) accumulates a huge amount of heat to the atmosphere. On the contrary, ML during the warming season is thinner than it is during the cooling season, being only a few tens of meters deep at mid- and high- latitudes, bounded by a shallow and sharp seasonal thermocline. Since the ML that directly communicates with the atmosphere is thin, the ocean has been considered to play a passive role in air-sea interactions during the warming season. In this study, we clarified that subsurface ocean plays an important role to seasonal changes of SST and heat capacity during the warming season using observational data of Argo and J-OFURO2, which is net heat flux (Qnet) data from satellites. To clarify the role of upper ocean to the Qnet during summer, we introduce a concept of heat penetration depth (HPD), defined as the depth to which Qnet distinctly penetrates below the seasonal thermocline. Then we assume vertical one dimensional process between Qnet and temporal heat content (HC) change integrating temperature from surface to HPD. The vertical one dimensional process can be assumed in almost mid- and high-latitude NP, and we successfully characterize the heat capacity in terms of the HC above the HPD. The downward heat penetration below the shallow seasonal thermocline is widely found throughout the NP. On the basis of a simple estimation that the amount of heat accumulated by summer Qnet in the NP, about two-thirds of Qnet penetrates below the shallow seasonal thermocline. The effect of heat penetration also makes a magnitude of seasonal change in SST to be smaller, at least a half of that the magnitude under the assumption

  10. Meteorological pre-processing of incoming solar radiation and heat flux over a sparse boreal forest at a northern site during winter conditions

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Batchvarova, E.

    2001-01-01

    Measurements from Northern Finland on radiation and turbulent fluxes over a sparse boreal forest with snow-covered ground were analysed. The measurements represent harsh winter conditions characterized by low sun angles. The absorption of incoming solar radiation in clear skies (turbidity......) was found to be a strong function of the solar elevation. At low solar elevation angles, commonly used expressions for turbidity did not fit the measurements well. A simple energy balance type met-processor performed well during daytime, but it was not satisfactory during night time. Simplifications...

  11. Measured and calculated clear-sky solar radiative fluxes during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS)

    Energy Technology Data Exchange (ETDEWEB)

    Valero, Francisco P. J. [Atmospheric Research Laboratory, Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, California (United States); Bush, Brett C. [Atmospheric Research Laboratory, Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, California (United States)

    1999-11-27

    Modeled and measured surface insolations are compared with the purpose of evaluating the ability of a radiative transfer model to predict the amount of solar radiation reaching the surface under clear-sky conditions. Model uncertainties are estimated by performing sensitivity studies for variations in aerosol optical depth, aerosol optical properties, water vapor profiles, ozone content, solar irradiance at the top of the atmosphere, and surface albedo. In this fashion, a range of possible calculated values is determined and compared to observations. Experimental errors are evaluated by comparison with independent, simultaneous measurements performed using two World Radiation Reference instrument arrays that were operational for a limited period during SUCCESS. Assuming a mineral aerosol, it is found that there is agreement between calculated and measured fluxes, with differences approximately equal to and within one standard deviation. Such agreement improves further if a layer containing a small amount of carbonaceous aerosol is added. The presence of carbonaceous aerosols is likely because occasional biomass burning activities took place during SUCCESS in the area around the experimental site (the clouds and radiation test bed operated by the Department of Energy in Oklahoma). (c) 2000 American Geophysical Union.

  12. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 4: Near-Earth solar wind speed, IMF, and open solar flux

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2014-04-01

    Full Text Available In the concluding paper of this tetralogy, we here use the different geomagnetic activity indices to reconstruct the near-Earth interplanetary magnetic field (IMF and solar wind flow speed, as well as the open solar flux (OSF from 1845 to the present day. The differences in how the various indices vary with near-Earth interplanetary parameters, which are here exploited to separate the effects of the IMF and solar wind speed, are shown to be statistically significant at the 93% level or above. Reconstructions are made using four combinations of different indices, compiled using different data and different algorithms, and the results are almost identical for all parameters. The correction to the aa index required is discussed by comparison with the Ap index from a more extensive network of mid-latitude stations. Data from the Helsinki magnetometer station is used to extend the aa index back to 1845 and the results confirmed by comparison with the nearby St Petersburg observatory. The optimum variations, using all available long-term geomagnetic indices, of the near-Earth IMF and solar wind speed, and of the open solar flux, are presented; all with ±2σ uncertainties computed using the Monte Carlo technique outlined in the earlier papers. The open solar flux variation derived is shown to be very similar indeed to that obtained using the method of Lockwood et al. (1999.

  13. Average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit

    Directory of Open Access Journals (Sweden)

    R. Kataoka

    2008-06-01

    Full Text Available We report average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit (GEO. It is found that seven of top ten extreme events at GEO during solar cycle 23 are associated with the magnetosphere inflation during the storm recovery phase as caused by the large-scale solar wind structure of very low dynamic pressure (<1.0 nPa during rapid speed decrease from very high (>650 km/s to typical (400–500 km/s in a few days. For the seven events, the solar wind parameters, geomagnetic activity indices, and relativistic electron flux and geomagnetic field at GEO are superposed at the local noon period of GOES satellites to investigate the physical cause. The average profiles support the "double inflation" mechanism that the rarefaction of the solar wind and subsequent magnetosphere inflation are one of the best conditions to produce the extreme flux enhancement at GEO because of the excellent magnetic confinement of relativistic electrons by reducing the drift loss of trapped electrons at dayside magnetopause.

  14. Reduced uncertainty of regional scale CLM predictions of net carbon fluxes and leaf area indices with estimated plant-specific parameters

    Science.gov (United States)

    Post, Hanna; Hendricks Franssen, Harrie-Jan; Han, Xujun; Baatz, Roland; Montzka, Carsten; Schmidt, Marius; Vereecken, Harry

    2016-04-01

    Reliable estimates of carbon fluxes and states at regional scales are required to reduce uncertainties in regional carbon balance estimates and to support decision making in environmental politics. In this work the Community Land Model version 4.5 (CLM4.5-BGC) was applied at a high spatial resolution (1 km2) for the Rur catchment in western Germany. In order to improve the model-data consistency of net ecosystem exchange (NEE) and leaf area index (LAI) for this study area, five plant functional type (PFT)-specific CLM4.5-BGC parameters were estimated with time series of half-hourly NEE data for one year in 2011/2012, using the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, a Markov Chain Monte Carlo (MCMC) approach. The parameters were estimated separately for four different plant functional types (needleleaf evergreen temperate tree, broadleaf deciduous temperate tree, C3-grass and C3-crop) at four different sites. The four sites are located inside or close to the Rur catchment. We evaluated modeled NEE for one year in 2012/2013 with NEE measured at seven eddy covariance sites in the catchment, including the four parameter estimation sites. Modeled LAI was evaluated by means of LAI derived from remotely sensed RapidEye images of about 18 days in 2011/2012. Performance indices were based on a comparison between measurements and (i) a reference run with CLM default parameters, and (ii) a 60 instance CLM ensemble with parameters sampled from the DREAM posterior probability density functions (pdfs). The difference between the observed and simulated NEE sum reduced 23% if estimated parameters instead of default parameters were used as input. The mean absolute difference between modeled and measured LAI was reduced by 59% on average. Simulated LAI was not only improved in terms of the absolute value but in some cases also in terms of the timing (beginning of vegetation onset), which was directly related to a substantial improvement of the NEE estimates in

  15. The Use of Two-Stream Approximations for the Parameterization of Solar Radiative Energy Fluxes through Vegetation.

    Science.gov (United States)

    Josepoh, Joachim H.; Laquinta, Jean; Pinty, Bernard

    1996-10-01

    Two-stream approximations have been used widely and for a long time in the field of radiative transfer through vegetation in various contexts and in the last 10 years also to model the hemispheric reflectance of vegetated surfaces in numerical models of the earth-atmosphere system.For a plane-parallel and turbid vegetation medium, the existence of rotational invariance allows the application of a conventional two-stream approximation to the phase function, based on an expansion in Legendre Polynomials. Three conditions have to be fulfilled to nuke this reduction possible in the case of vegetation. The scattering function of single leaves must be bi-Lambertian, the azimuthal distribution of leaf normals must be uniform, and the azimuthally averaged Leaf Area Normal Distribution (LAND) must be either uniform or planophile. The first and second assumptions have been shown to he acceptable by other researchers and. in fact, are usually assumed explicitly or implicitly when dealing with radiative transfer through canopies. The third one, on the shape of the azimuthally averaged LAND, although investigated before, is subjected to a detailed sensitivity test in this study, using a set of synthetic LAND's as well as experimental data for 17 plant canopies.It is shown that the radiative energy flux equations are relatively insensitive to the exact form of the LAND. The experimental Ross functions and hemispheric reflectances lie between those for the synthetic cases of planophile and erectophile LANDS. However, only the uniform and planophile LANDs lead to canopy hemispheric reflectances, which are markedly different from one another.The analytical two-stream solutions for the either the planophile or the uniform LAND cases may be used to model the radiative fluxes through plant canopies in the solar spectral range. The choice between the two for any particular case must he made on the basis of experimental data.

  16. Competitiveness of grid-connected solar electricity in Sweden - as seen from the perspective of the utilities and the net owners; Konkurrenskraft foer naetansluten solel i Sverige - sett ur kraftfoeretagens och naetaegarnas perspektiv

    Energy Technology Data Exchange (ETDEWEB)

    Carlstedt, Nils-Eric [Vattenfall Power Consultant AB, Stockholm (Sweden); Karlsson, Bjoern; Kjellsson, Elisabeth; Samuelsson, Olof [Faculty of Engineering (LTH), Lund University, Lund (Sweden); Neij, Lena [International Institute for Industrial Environmental Economics, Lund University, Lund (Sweden)

    2006-12-15

    The objective of this report was to analyse the competitiveness of grid-connected solar power in Sweden - and specifically the competitiveness for energy companies and net owners. In theory, solar power could to a large extent fulfil the electricity demand in Sweden, especially in the summer. However, the high cost of solar cells is a major barrier to implementation. Future technology development and increased efficiency could, however, lead to important cost reductions. The question is if such expected cost reductions would make grid-connected solar power a preferable investment option for energy companies and an interesting alternative for the net owners. The results of the study show that solar power will not be a competitive alternative for the energy companies in Sweden, not in 2020 and probably not in 2050. Other alternatives such as new investments in wind turbines and bio-mass based technology options will be producing electricity at a lower cost. Moreover, solar power will have an unfavourable production profile, generating power in the summertime when less needed. However, by using the reservoirs of the hydro power systems in Sweden as storage capacity, approximately 5 TWh solar power could be allowed in the Swedish electricity system. The results of the study indicate that solar power could have a positive effect on the electricity distribution system since distributed generation will result in lower losses in the system. Moreover, solar power will be produced during daytime when the electricity demand will peak. One of the main challenges for the net owners would be to design the net in such a way that the net and the solar cells could work together in the best possible way. Another challenge would be the high cost for connecting the solar cells to the grid; this cost needs to be reduced. Looking instead at the house-owners as possible investors, solar cells appear as a much more attractive alternative for the future, the value of the solar power is

  17. The behavior of transverse waves in nonuniform solar flux tubes. II. Implications for coronal loop seismology

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramón [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Goossens, Marcel, E-mail: roberto.soler@uib.es [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)

    2014-02-01

    The seismology of coronal loops using observations of damped transverse oscillations in combination with results from theoretical models is a tool to indirectly infer physical parameters in the solar atmospheric plasma. Existing seismology schemes based on approximations of the period and damping time of kink oscillations are often used beyond their theoretical range of applicability. These approximations assume that the variation of density across the loop is confined to a nonuniform layer much thinner than the radius of the loop, but the results of the inversion problem often do not satisfy this preliminary hypothesis. Here, we determine the accuracy of the analytic approximations of the period and damping time, and the impact on seismology estimates when largely nonuniform loops are considered. We find that the accuracy of the approximations when used beyond their range of applicability is strongly affected by the form of the density profile across the loop, that is observationally unknown and so must be arbitrarily imposed as part of the theoretical model. The error associated with the analytic approximations can be larger than 50% even for relatively thin nonuniform layers. This error directly affects the accuracy of approximate seismology estimates compared to actual numerical inversions. In addition, assuming different density profiles can produce noncoincident intervals of the seismic variables in inversions of the same event. The ignorance about the true shape of density variation across the loop is an important source of error that may dispute the reliability of parameters seismically inferred assuming an ad hoc density profile.

  18. The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations

    Science.gov (United States)

    Nandy, Dibyendu; Bhowmik, Prantika; Yeates, Anthony R.; Panda, Suman; Tarafder, Rajashik; Dash, Soumyaranjan

    2018-01-01

    On 2017 August 21, a total solar eclipse swept across the contiguous United States, providing excellent opportunities for diagnostics of the Sun’s corona. The Sun’s coronal structure is notoriously difficult to observe except during solar eclipses; thus, theoretical models must be relied upon for inferring the underlying magnetic structure of the Sun’s outer atmosphere. These models are necessary for understanding the role of magnetic fields in the heating of the corona to a million degrees and the generation of severe space weather. Here we present a methodology for predicting the structure of the coronal field based on model forward runs of a solar surface flux transport model, whose predicted surface field is utilized to extrapolate future coronal magnetic field structures. This prescription was applied to the 2017 August 21 solar eclipse. A post-eclipse analysis shows good agreement between model simulated and observed coronal structures and their locations on the limb. We demonstrate that slow changes in the Sun’s surface magnetic field distribution driven by long-term flux emergence and its evolution governs large-scale coronal structures with a (plausibly cycle-phase dependent) dynamical memory timescale on the order of a few solar rotations, opening up the possibility for large-scale, global corona predictions at least a month in advance.

  19. Water, Energy, and Carbon with Artificial Neural Networks (WECANN): a statistically based estimate of global surface turbulent fluxes and gross primary productivity using solar-induced fluorescence

    Science.gov (United States)

    Hamed Alemohammad, Seyed; Fang, Bin; Konings, Alexandra G.; Aires, Filipe; Green, Julia K.; Kolassa, Jana; Miralles, Diego; Prigent, Catherine; Gentine, Pierre

    2017-09-01

    A new global estimate of surface turbulent fluxes, latent heat flux (LE) and sensible heat flux (H), and gross primary production (GPP) is developed using a machine learning approach informed by novel remotely sensed solar-induced fluorescence (SIF) and other radiative and meteorological variables. This is the first study to jointly retrieve LE, H, and GPP using SIF observations. The approach uses an artificial neural network (ANN) with a target dataset generated from three independent data sources, weighted based on a triple collocation (TC) algorithm. The new retrieval, named Water, Energy, and Carbon with Artificial Neural Networks (WECANN), provides estimates of LE, H, and GPP from 2007 to 2015 at 1° × 1° spatial resolution and at monthly time resolution. The quality of ANN training is assessed using the target data, and the WECANN retrievals are evaluated using eddy covariance tower estimates from the FLUXNET network across various climates and conditions. When compared to eddy covariance estimates, WECANN typically outperforms other products, particularly for sensible and latent heat fluxes. Analyzing WECANN retrievals across three extreme drought and heat wave events demonstrates the capability of the retrievals to capture the extent of these events. Uncertainty estimates of the retrievals are analyzed and the interannual variability in average global and regional fluxes shows the impact of distinct climatic events - such as the 2015 El Niño - on surface turbulent fluxes and GPP.

  20. MICROWAVE IMAGING OF A HOT FLUX ROPE STRUCTURE DURING THE PRE-IMPULSIVE STAGE OF AN ERUPTIVE M7.7 SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhao; Chen, Yao; Song, Hongqiang; Chandrashekhar, Kalugodu; Jiao, Fangran [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China); Huang, Guangli [Purple Mountain Observatory, Chinese Academy of Sciences (CAS), Nanjing, 210008 (China); Nakajima, Hiroshi [Nobeyama Radio Observatory, NAOJ, 462-2 Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305 (Japan); Melnikov, Victor [Central Astronomical Observatory at Pulkovo, Russian Academy of Sciences, Saint Petersburg 196140 (Russian Federation); Liu, Wei [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Li, Gang, E-mail: yaochen@sdu.edu.cn [Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2016-04-01

    Corona structures and processes during the pre-impulsive stage of solar eruption are crucial to understanding the physics leading to the subsequent explosive energy release. Here we present the first microwave imaging study of a hot flux rope structure during the pre-impulsive stage of an eruptive M7.7 solar flare, with the Nobeyama Radioheliograph at 17 GHz. The flux rope is also observed by the SDO/AIA in its hot passbands of 94 and 131 Å. In the microwave data, it is revealed as an overall arcade-like structure consisting of several intensity enhancements bridged by generally weak emissions, with brightness temperatures (T{sub B}) varying from ∼10,000 K to ∼20,000 K. Locations of microwave intensity enhancements along the structure remain relatively fixed at certain specific parts of the flux rope, indicating that the distribution of emitting electrons is affected by the large-scale magnetic configuration of the twisted flux rope. Wavelet analysis shows a pronounced 2 minute period of the microwave T{sub B} variation during the pre-impulsive stage of interest. The period agrees well with that reported for AIA sunward-contracting loops and upward ejective plasmoids (suggested to be reconnection outflows). This suggests that both periodicities are controlled by the same reconnection process that takes place intermittently at a 2 minute timescale. We infer that at least a part of the emission is excited by non-thermal energetic electrons via the gyro-synchrotron mechanism. The study demonstrates the potential of microwave imaging in exploring the flux rope magnetic geometry and relevant reconnection process during the onset of solar eruption.

  1. Modelling daily to seasonal carbon fluxes and annual net ecosystem carbon balance of cereal grain-cropland using DailyDayCent: A model data comparison

    OpenAIRE

    Chabbi, Abad; Smith, Pete

    2018-01-01

    Croplands are important not only for food and fibre, but also for their global climate change mitigation and carbon (C) sequestration potentials. Measurements and modelling of daily C fluxes and annual C balance, which are needed for optimizing such global potentials in croplands, are difficult since many measurements, and the correct simulation of different ecosystem processes are needed. In the present study, a biogeochemical ecosystem model (DailyDayCent) was applied to simulate daily to s...

  2. Estimativa do saldo de radiação em girassol como função da radiação solar global Estimation of net radiation in sunflower as a function of solar radiation

    Directory of Open Access Journals (Sweden)

    Arno B Heldwein

    2012-02-01

    Full Text Available Objetivou-se com este trabalho a obtenção de modelos para a estimativa do saldo de radiação (Q* a partir da radiação solar global incidente (Rg sobre dosseis de plantas de girassol. Os experimentos foram conduzidos na área experimental da Universidade Federal de Santa Maria, nos anos de 2007, 2008 e 2009. O Q* foi medido com saldos radiômetros instalados acima das plantas e a Rg em estações meteorológicas automáticas. Para fins de cálculo foram efetuadas as somas diárias de Q* e de Rg, obtendo-se a relação entre Q* e Rg para cada dia. Obtiveram-se, então, modelos com elevado coeficiente de determinação e baixo RQME no teste entre valores medidos e estimados de um banco de dados independente, indicando precisão na estimativa do saldo de radiação em dosseis de girassol, independendo da época de cultivo no ano. A função linear geral obtida com dados de diferentes épocas de cultivo foi: Q* = 0,5285 Rg (R² = 0,95, que no teste apresentou RQME = 1,04 MJ m-2 d-1. Conclui-se que o saldo de radiação (Q* pode ser estimado utilizando-se a radiação solar global medida em estações automáticas, com precisão suficiente para os diferentes fins na agrometeorologia do girassol.This study aimed to develop models for estimating the net radiation (Q * from the incident solar radiation (Rg on canopies of sunflower plants. The experiments were conducted at the Plant Science Department of the Federal University of Santa Maria in 2007, 2008 and 2009 years. Q* was measured by net radiometers above the plants and Rg by automatic weather stations. For purposes of calculation, daily sums of Q* and Rg were performed, obtaining the relationship between Q* and Rg for each day. Models with high coefficient of determination and low RQME were obtained in test between measured and estimated values from an independent database, indicating precision to estimate net radiation in sunflower canopies, regardless of cultivation time in year. The general

  3. HANPP Collection: Global Patterns in Net Primary Productivity (NPP)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Global Patterns in Net Primary Productivity (NPP) portion of the Human Appropriation of Net Primary Productivity (HANPP) Collection maps the net amount of solar...

  4. Solar Magnetic Flux Ropes

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  5. Comparison of net CO2 fluxes measured with open- and closed-path infrared gas analyzers in an urban complex environment

    DEFF Research Database (Denmark)

    Järvi, L.; Mammarella, I.; Eugster, W.

    2009-01-01

    and their suitability to accurately measure CO2 exchange in such non-ideal landscape. In addition, this study examined the effect of open-path sensor heating on measured fluxes in urban terrain, and these results were compared with similar measurements made above a temperate beech forest in Denmark. The correlation...... improved the performance of the open-path analyzer by reducing discrepancies in NSE at the urban site to 2% and decreasing the difference in NSE from 67% to 7% at the forest site. Overall, the site-specific approach gave the best results at both sites and, if possible, it should be preferred in the sensor...

  6. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  7. Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Marszal, Anna Joanna; Bourrelle, Julien S.; Musall, Eike

    2010-01-01

    and identify possible renewable energy supply options which may be considered in calculations. Finally, the gap between the methodology proposed by each organisation and their respective national building code is assessed; providing an overview of the possible changes building codes will need to undergo......The international cooperation project IEA SHC Task 40 / ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings”, attempts to develop a common understanding and to set up the basis for an international definition framework of Net Zero Energy Buildings (Net ZEBs). The understanding of such buildings...... parameters used in the calculations are discussed and the various renewable supply options considered in the methodologies are summarised graphically. Thus, the paper helps to understand different existing approaches to calculate energy balance in Net ZEBs, highlights the importance of variables selection...

  8. Global Distribution and Variations of NO Infrared Radiative Flux and Its Responses to Solar Activity and Geomagnetic Activity in the Thermosphere

    Science.gov (United States)

    Tang, Chaoli; Wei, Yuanyuan; Liu, Dong; Luo, Tao; Dai, Congming; Wei, Heli

    2017-12-01

    The global distribution and variations of NO infrared radiative flux (NO-IRF) are presented during 2002-2016 in the thermosphere covering 100-280 km altitude based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data set. For investigating the spatial variations of the mutual relationship between NO-IRF and solar activity, the altitude ranges from 100 km to 280 km are divided into 90 altitude bins, and the latitude regions of 83°S-83°N are divided into 16 latitude bins. By processing about 1.8E9 NO-IRF observation values from about 5E6 vertical nighttime profiles recorded in SABER data set, we obtained more than 4.1E8 samples of NO-IRF. The annual-mean values of NO-IRF are then calculated by all available NO-IRF samples within each latitude and altitude bin. Local latitudinal maxima in NO-IRF are found between 120 and 145 km altitude, and the maximum NO-IRF located at polar regions are 3 times more than that of the minimum at equatorial region. The influences of solar and geomagnetic activity on the spatial variations of NO-IRF are investigated. Both the NO-IRF and its response to solar and geomagnetic activity show nearly symmetric distribution between the two hemispheres. It is demonstrated that the observed changes in NO-IRF at altitudes between 100 and 225 km correlate well with the changes in solar activity. The NO-IRF at solar maximum is about 4 times than that at solar minimum, and the current maximum of NO-IRF in 2014 is less than 70% of the prior maximum in 2001. For the first time, the response ranges of the NO-IRF to solar and geomagnetic activity at different altitudes and latitudes are reported.

  9. Marine and continental aerosol effects on the upwelling solar radiation flux in Southern Portugal during the ACE-2 experiment

    Directory of Open Access Journals (Sweden)

    U. Bonafé

    2003-06-01

    CLEARCOLUMN (ACE-2 experiment in June and July 1997. These spectral series were then analysed with the King inversion method to defi ne the size-distribution curves of columnar aerosol particle total number and volume, assuming values of both real and imaginary parts of the particulate refractive index obtained on the six days by combining our measurements with simultaneous sky-brightness measurements taken by the Leipzig University group. For these results, we then calculated the daily time-patterns of the average single scattering albedo of the columnar aerosols, fi nding instantaneous values ranging between 0.70 and 0.96 on those days, with daily mean values varying from 0.83 to 0.95. Furthermore, for each spectral series of aerosol optical depth, we determined the instantaneous change DF^ induced by the columnar aerosols on the upwelling solar radiation flux leaving the atmosphere, over oceanic areas presenting low surface albedo. The 24-h average values of DF^ obtained on the six days were found to increase as a function of the daily mean value of aerosol optical depth at the 0.55 mm wavelength, following relationship curves whose positive slope coeffi cients decrease gradually with the single scattering albedo of the columnar aerosols. The said curves can be used to achieve reliable estimates of change DF^ directly from daily ground-based multispectral measurements of aerosol optical depth and skybrightness at different angular distances from the Sun.

  10. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  11. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  12. Combining Observations in the Reflective Solar and Thermal Domains for Improved Mapping of Carbon, Water and Energy FLuxes

    Science.gov (United States)

    Houborg, Rasmus; Anderson, Martha; Kustas, Bill; Rodell, Matthew

    2011-01-01

    This study investigates the utility of integrating remotely sensed estimates of leaf chlorophyll (C(sub ab)) into a thermal-based Two-Source Energy Balance (TSEB) model that estimates land-surface CO2 and energy fluxes using an analytical, light-use-efficiency (LUE) based model of canopy resistance. Day to day variations in nominal LUE (LUE(sub n)) were assessed for a corn crop field in Maryland U.S.A. through model calibration with CO2 flux tower observations. The optimized daily LUE(sub n) values were then compared to estimates of C(sub ab) integrated from gridded maps of chlorophyll content weighted over the tower flux source area. Changes in Cab exhibited a curvilinear relationship with corresponding changes in daily calibrated LUE(sub n) values derived from the tower flux data, and hourly water, energy and carbon flux estimation accuracies from TSEB were significantly improved when using C(sub ab) for delineating spatio-temporal variations in LUE(sub n). The results demonstrate the synergy between thermal infrared and shortwave reflective wavebands in producing valuable remote sensing data for monitoring of carbon and water fluxes.

  13. NETS FOR PEACH PROTECTED CULTIVATION

    Directory of Open Access Journals (Sweden)

    Evelia Schettini

    2012-06-01

    Full Text Available The aim of this paper was to investigate the radiometric properties of coloured nets used to protect a peach cultivation. The modifications of the solar spectral distribution, mainly in the R and FR wavelength band, influence plant photomorphogenesis by means of the phytochrome and cryptochrome. The phytochrome response is characterized in terms of radiation rate in the red wavelengths (R, 600-700 nm to that in the farred radiation (FR, 700-800 nm, i.e. the R/FR ratio. The effects of the blue radiation (B, 400-500 nm is investigated by the ratio between the blue radiation and the far-red radiation, i.e. the B/FR ratio. A BLUE net, a RED net, a YELLOW net, a PEARL net, a GREY net and a NEUTRAL net were tested in Bari (Italy, latitude 41° 05’ N. Peach trees were located in pots inside the greenhouses and in open field. The growth of the trees cultivated in open field was lower in comparison to the growth of the trees grown under the nets. The RED, PEARL, YELLOW and GREY nets increased the growth of the trees more than the other nets. The nets positively influenced the fruit characteristics, such as fruit weight and flesh firmness.

  14. The CU mobile Solar Occultation Flux instrument: structure functions and emission rates of NH3, NO2 and C2H6

    Science.gov (United States)

    Kille, Natalie; Baidar, Sunil; Handley, Philip; Ortega, Ivan; Sinreich, Roman; Cooper, Owen R.; Hase, Frank; Hannigan, James W.; Pfister, Gabriele; Volkamer, Rainer

    2017-02-01

    We describe the University of Colorado mobile Solar Occultation Flux instrument (CU mobile SOF). The instrument consists of a digital mobile solar tracker that is coupled to a Fourier transform spectrometer (FTS) of 0.5 cm-1 resolution and a UV-visible spectrometer (UV-vis) of 0.55 nm resolution. The instrument is used to simultaneously measure the absorption of ammonia (NH3), ethane (C2H6) and nitrogen dioxide (NO2) along the direct solar beam from a moving laboratory. These direct-sun observations provide high photon flux and enable measurements of vertical column densities (VCDs) with geometric air mass factors, high temporal resolution of 2 s and spatial resolution of 5-19 m. It is shown that the instrument line shape (ILS) of the FTS is independent of the azimuth and elevation angle pointing of the solar tracker. Further, collocated measurements next to a high-resolution FTS at the National Center for Atmospheric Research (HR-NCAR-FTS) show that the CU mobile SOF measurements of NH3 and C2H6 are precise and accurate; the VCD error at high signal to noise ratio is 2-7 %. During the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) from 21 July to 3 September 2014 in Colorado, the CU mobile SOF instrument measured median (minimum, maximum) VCDs of 4.3 (0.5, 45) × 1016 molecules cm-2 NH3, 0.30 (0.06, 2.23) × 1016 molecules cm-2 NO2 and 3.5 (1.5, 7.7) × 1016 molecules cm-2 C2H6. All gases were detected in larger 95 % of the spectra recorded in urban, semi-polluted rural and remote rural areas of the Colorado Front Range. We calculate structure functions based on VCDs, which describe the variability of a gas column over distance, and find the largest variability for NH3. The structure functions suggest that currently available satellites resolve about 10 % of the observed NH3 and NO2 VCD variability in the study area. We further quantify the trace gas emission fluxes of NH3 and C2H6 and production rates of NO2 from concentrated animal feeding

  15. Measurements of industrial emissions of VOCs, NH3, NO2 and SO2 in Texas using the Solar Occultation Flux method and mobile DOAS

    Science.gov (United States)

    Mellqvist, J.; Samuelsson, J.; Rivera, C.; Lefer, B.; Patel, M.

    2007-12-01

    Solar Occultation Flux (SOF) measurements of olefines and alkanes have been conducted to pin-point and quantify the largest sources of olefines and alkanes in the vicinity of Houston and in south eastern Texas during September 2006. The SOF measurements were part of the extensive summer campaign TexAQS 2006, included in the Second Texas Air Quality Study (TexAQS II). The SOF technique is an optical method utilizing the absorption of direct solar infrared radiation in the 1.8-14 micrometer range for retrieval of total columns of various species such as ethylene, propylene, ammonia and alkanes. The instrument is carried on a mobile platform, making it possible to conduct transects of the emission plume downwind an industry, and thus integrate all the molecules of the plume cross section in real time. By multiplying with the plume wind speed, the total flux emerging from the source is obtained. Flux estimates with SOF were obtained for the large petrochemical and refining complexes around the Houston area. This was done in parallell with airborne plume studies by other parties. The primary research goal was to supply a data set for emission inventory comparisons and for input to models looking at the strong ozone production in Texas. The SOF measurements show that the hourly gas emissions from the Houston Ship channel area correspond to about 1 metric ton of ethylene, 1.5 tons of propylene, 12 tons of alkanes, 1/4 ton of NH3 and about 5 tons of SO2 and NO2. For the VOCs this is an order of magnitude or greater than reported VOC emissions in the 2004 inventory.

  16. A THEMIS Survey of Flux Ropes and Traveling Compression Regions: Location of the Near-Earth Reconnection Site During Solar Minimum

    Science.gov (United States)

    Imber, S. M.; Slavin, J. A.; Auster, H. U.; Angelopoulos, V.

    2011-01-01

    A statistical study of flux ropes and traveling compression regions (TCRs) during the Time History of Events and Macroscale Interactions during Substorms (THEMIS) second tail season has been performed. A combined total of 135 flux ropes and TCRs in the range GSM X approx -14 to -31 R(sub E) were identified, many of these occurring in series of two or more events separated by a few tens of seconds. Those occurring within 10 min of each other were combined into aggregated reconnection events. For the purposes of this survey, these are most likely the products of reconnect ion occurring simultaneously at multiple, closely spaced x-lines as opposed to statistically independent episodes of reconnection. The 135 flux ropes and TCRs were grouped into 87 reconnection events; of these, 28 were moving tailward and 59 were moving Earthward. The average location of the near-Earth x-line determined from statistical analysis of these reconnection events is (X(sub GSM), Y*(sub GSM)) = (-30R(sub E), 5R(sub E)), where Y* includes a correction for the solar aberration angle. A strong east-west asymmetry is present in the tailward events, with >80% being observed at GSM Y* > O. Our results indicate that the Earthward flows are similarly asymmetric in the midtail region, becoming more symmetric inside - 18 R(sub E). Superposed epoch analyses indicate that the occurrence of reconnection closer to the Earth, i.e., X > -20 R(sub E), is associated with elevated solar wind velocity and enhanced negative interplanetary magnetic field B(sub z). Reconnection events taking place closer to the Earth are also far more effective in producing geomagnetic activity, judged by the AL index, than reconnection initiated beyond X approx -25 R(sub E).

  17. Net ecosystem exchange from five land-use transitions to bioenergy crops from four locations across the UK - The Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project.

    Science.gov (United States)

    Xenakis, Georgios; Perks, Mike; Harris, Zoe M.; McCalmont, Jon; Rylett, Daniel; Brooks, Milo; Evans, Jonathan G.; Finch, Jon; Rowe, Rebecca; Morrison, Ross; Alberti, Giorgio; Donnison, Ian; Siebicke, Lukas; Morison, James; Taylor, Gail; McNamara, Niall P.

    2016-04-01

    A major part of international agreements on combating climate change is the conversion from a fossil fuel economy to a low carbon economy. Bioenergy crops have been proposed as a way to improve energy security while reducing CO2 emissions to help mitigate the effects of climate change. However, the impact of land-use change from a traditional land use (e.g., arable and grassland) to bioenergy cropping systems on greenhouse gas balance (GHG) and carbon stocks are poorly quantified at this time. The Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project was commissioned and funded by the Energy Technologies Institute (ETI) to provide scientific evidence within the UK on a range of land-use conversions (LUC) to bioenergy crops. The ELUM network consists of seven partners investigating five LUCs in four locations including Scotland, Wales, North and South England. Transitions included grasslands to short rotation forestry (SRF), to short rotation coppice willow (SRC) and to Miscanthus and arable to SRC and Miscanthus Measurements of net ecosystem exchange (NEE) along with continuous measurements of meteorological conditions were made at seven sub-sites over a two-year period. Results showed that, over two years, two of the land-uses, a grassland in South England and a grassland conversion to Miscanthus in Wales were net sources of carbon. The greatest carbon sink was into the SRF site in Scotland followed by the SRC willow in South England. The annual terrestrial ecosystem respiration (TER) for the SRC willow in North and South Sussex sites were similar, but the annual GPP at the South England site was about 27% higher than that the North England site. Establishing a long term network will allow us to continue monitoring the effects of land use change on whole ecosystem carbon balance, providing an insight into which types of LUC are suitable for bioenergy cropping in the UK.

  18. Estimation of the hydrogen flux from a PEM electrolyzer, based in the solar irradiation measured in Zacatecas Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Villagrana-Munoz, L.E.; Garcia-Saldivar, V.M.; Escalante-Garcia, I.L. [Univ. Autonoma de Zacatecas, Zacatecas (Mexico). Unidad Academica de Ciencias Quimicas; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo (Mexico)

    2010-07-15

    The current cost of obtaining hydrogen from electrolyzers is higher than the cost of producing fossil fuels. However, with advances in technology and greater use of alternative energy sources, the cost of electrolytic hydrogen production may decrease to the point of being competitive. This study calculated how much hydrogen can be produced in a typical polymer exchange membrane (PEM) electrolyzer. Local solar irradiation measurements were carried out from November 2007 to April 2008 at the Campus Siglo 21 Solarimetric Station at Zacatecas University in Mexico. The mean irradiation measured was 6.6 kW-h per m{sup 2}. Based on the solar data obtained at the station, the hydrogen produced by a typical solar-hydrogen (SH) system was evaluated. The study showed that an important quantity of hydrogen as an energy vector could be obtained from solar radiation. April was determined to be the month of maximum hydrogen production. The lowest hydrogen production was in November. The data obtained during this study can be used to evaluate the solar renewable energy resource expressed as hydrogen production. 19 refs., 1 tab., 4 figs.

  19. Flux Emergence (Theory

    Directory of Open Access Journals (Sweden)

    Mark C. M. Cheung

    2014-07-01

    Full Text Available Magnetic flux emergence from the solar convection zone into the overlying atmosphere is the driver of a diverse range of phenomena associated with solar activity. In this article, we introduce theoretical concepts central to the study of flux emergence and discuss how the inclusion of different physical effects (e.g., magnetic buoyancy, magnetoconvection, reconnection, magnetic twist, interaction with ambient field in models impact the evolution of the emerging field and plasma.

  20. Temporal Variability in Vertical Groundwater Fluxes and the Effect of Solar Radiation on Streambed Temperatures Based on Vertical High Resolution Distributed Temperature Sensing

    Science.gov (United States)

    Sebok, E.; Karan, S.; Engesgaard, P. K.; Duque, C.

    2013-12-01

    Due to its large spatial and temporal variability, groundwater discharge to streams is difficult to quantify. Methods using vertical streambed temperature profiles to estimate vertical fluxes are often of coarse vertical spatial resolution and neglect to account for the natural heterogeneity in thermal conductivity of streambed sediments. Here we report on a field investigation in a stream, where air, stream water and streambed sediment temperatures were measured by Distributed Temperature Sensing (DTS) with high spatial resolution to; (i) detect spatial and temporal variability in groundwater discharge based on vertical streambed temperature profiles, (ii) study the thermal regime of streambed sediments exposed to different solar radiation influence, (iii) describe the effect of solar radiation on the measured streambed temperatures. The study was carried out at a field site located along Holtum stream, in Western Denmark. The 3 m wide stream has a sandy streambed with a cobbled armour layer, a mean discharge of 200 l/s and a mean depth of 0.3 m. Streambed temperatures were measured with a high-resolution DTS system (HR-DTS). By helically wrapping the fiber optic cable around two PVC pipes of 0.05 m and 0.075 m outer diameter over 1.5 m length, temperature measurements were recorded with 5.7 mm and 3.8 mm vertical spacing, respectively. The HR-DTS systems were installed 0.7 m deep in the streambed sediments, crossing both the sediment-water and the water-air interface, thus yielding high resolution water and air temperature data as well. One of the HR-DTS systems was installed in the open stream channel with only topographical shading, while the other HR-DTS system was placed 7 m upstream, under the canopy of a tree, thus representing the shaded conditions with reduced influence of solar radiation. Temperature measurements were taken with 30 min intervals between 16 April and 25 June 2013. The thermal conductivity of streambed sediments was calibrated in a 1D flow

  1. Measurements of the atmospheric neutrino flux by Super-Kamiokande: energy spectra, geomagnetic effects, and solar modulation

    CERN Document Server

    Richard, E; Abe, K; Haga, Y; Hayato, Y; Ikeda, M; Iyogi, K; Kameda, J; Kishimoto, Y; Miura, M; Moriyama, S; Nakahata, M; Nakajima, T; Nakano, Y; Nakayama, S; Orii, A; Sekiya, H; Shiozawa, M; Takeda, A; Tanaka, H; Tomura, T; Wendell, R A; Akutsu, R; Irvine, T; Kajita, T; Kaneyuki, K; Nishimura, Y; Labarga, L; Fernandez, P; Gustafson, J; Kachulis, C; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Berkman, S; Nantais, C M; Tanaka, H A; Tobayama, S; Goldhaber, M; Kropp, W R; Mine, S; Weatherly, P; Smy, M B; Sobel, H W; Takhistov, V; Ganezer, K S; Hartfiel, B L; Hill, J; Hong, N; Kim, J Y; Lim, I T; Park, R G; Himmel, A; Li, Z; OSullivan, E; Scholberg, K; Walter, C W; Wongjirad, T; Ishizuka, T; Tasaka, S; Jang, J S; Learned, J G; Matsuno, S; Smith, S N; Friend, M; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Suzuki, A T; Takeuchi, Y; Yano, T; Cao, S V; Hiraki, T; Hirota, S; Huang, K; Kikawa, T; Minamino, A; Nakaya, T; Suzuki, K; Fukuda, Y; Choi, K; Itow, Y; Suzuki, T; Mijakowski, P; Frankiewicz, K; Hignight, J; Imber, J; Jung, C K; Li, X; Palomino, J L; Wilking, M J; Yanagisawa, C; Fukuda, D; Ishino, H; Kayano, T; Kibayashi, A; Koshio, Y; Mori, T; Sakuda, M; Xu, C; Kuno, Y; Tacik, R; Kim, S B; Okazawa, H; Choi, Y; Nishijima, K; Koshiba, M; Totsuka, Y; Suda, Y; Yokoyama, M; Bronner, C; Hartz, M; Martens, K; Marti, Ll; Suzuki, Y; Vagins, M R; Martin, J F; Konaka, A; Chen, S; Zhang, Y; Wilkes, R J

    2015-01-01

    A comprehensive study on the atmospheric neutrino flux in the energy region from sub-GeV up to several TeV using the Super-Kamiokande water Cherenkov detector is presented in this paper. The energy and azimuthal spectra of the atmospheric ${\

  2. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  3. Altitude distribution of electron concentration in ionospheric D-region in presence of time-varying solar radiation flux

    Energy Technology Data Exchange (ETDEWEB)

    Nina, A., E-mail: sandrast@ipb.ac.rs [Institute of Physics, University of Belgrade, P.O. Box 57, Belgrade (Serbia); Cadez, V. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Sreckovic, V. [Institute of Physics, University of Belgrade, P.O. Box 57, Belgrade (Serbia); Sulic, D. [Faculty of Ecology and Environmental Protection, Union - Nikola Tesla University, Cara Dusana 62, 11000 Belgrade (Serbia)

    2012-05-15

    In this paper, we study the influence of solar flares on electron concentration in the terrestrial ionospheric D-region by analyzing the amplitude and phase time variations of very low frequency (VLF) radio waves emitted by DHO transmitter (Germany) and recorded by the AWESOME receiver in Belgrade (Serbia) in real time. The rise of photo-ionization rate in the ionospheric D-region is a typical consequence of solar flare activity as recorded by GOES-15 satellite for the event on March 24, 2011 between 12:01 UT and 12:11 UT. At altitudes around 70 km, the photo-ionization and recombination are the dominant electron gain and electron loss processes, respectively. We analyze the relative contribution of each of these two processes in the resulting electron concentration variation in perturbed ionosphere.

  4. TIME DEPENDENCE OF THE PROTON FLUX MEASURED BY PAMELA DURING THE 2006 JULY-2009 DECEMBER SOLAR MINIMUM

    Energy Technology Data Exchange (ETDEWEB)

    Adriani, O.; Bongi, M. [Department of Physics, University of Florence, I-50019 Sesto Fiorentino, Florence (Italy); Barbarino, G. C. [Department of Physics, University of Naples ' ' Federico II' ' , I-80126 Naples (Italy); Bazilevskaya, G. A. [Lebedev Physical Institute, RU-119991 Moscow (Russian Federation); Bellotti, R.; Bruno, A. [Department of Physics, University of Bari, I-70126 Bari (Italy); Boezio, M.; Bonvicini, V.; Carbone, R. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Bogomolov, E. A. [Ioffe Physical Technical Institute, RU-194021 St. Petersburg (Russian Federation); Borisov, S.; De Pascale, M. P.; De Santis, C.; De Simone, N. [INFN, Sezione di Rome ' ' Tor Vergata' ' , I-00133 Rome (Italy); Bottai, S. [INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence (Italy); Cafagna, F. [INFN, Sezione di Bari, I-70126 Bari (Italy); Campana, D. [INFN, Sezione di Naples, I-80126 Naples (Italy); Carlson, P. [KTH, Department of Physics, and the Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691 Stockholm (Sweden); Casolino, M. [Department of Physics, University of Rome ' ' Tor Vergata' ' , I-00133 Rome (Italy); Castellini, G. [IFAC, I-50019 Sesto Fiorentino, Florence (Italy); and others

    2013-03-10

    The energy spectra of galactic cosmic rays carry fundamental information regarding their origin and propagation. These spectra, when measured near Earth, are significantly affected by the solar magnetic field. A comprehensive description of the cosmic radiation must therefore include the transport and modulation of cosmic rays inside the heliosphere. During the end of the last decade, the Sun underwent a peculiarly long quiet phase well suited to study modulation processes. In this paper we present proton spectra measured from 2006 July to 2009 December by PAMELA. The large collected statistics of protons allowed the time variation to be followed on a nearly monthly basis down to 400 MV. Data are compared with a state-of-the-art three-dimensional model of solar modulation.

  5. Petri Nets

    Indian Academy of Sciences (India)

    Associate Professor of. Computer Science and. Automation at the Indian. Institute of Science,. Bangalore. His research interests are broadly in the areas of stochastic modeling and scheduling methodologies for future factories; and object oriented modeling. GENERAL I ARTICLE. Petri Nets. 1. Overview and Foundations.

  6. Petri Nets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Petri Nets - Overview and Foundations. Y Narahari. General Article Volume 4 Issue 8 August 1999 pp ... Author Affiliations. Y Narahari1. Department ot Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  7. HANPP Collection: Global Patterns in Net Primary Productivity (NPP)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Global Patterns in Net Primary Productivity (NPP) portion of the HANPP Collection maps the net amount of solar energy converted to plant organic matter through...

  8. Master Robotic Net

    Directory of Open Access Journals (Sweden)

    Vladimir Lipunov

    2010-01-01

    Full Text Available The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa, search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

  9. Surface-air mercury fluxes across Western North America: A synthesis of spatial trends and controlling variables

    Science.gov (United States)

    Eckley, Chris S.; Tate, Michael T.; Lin, Che-Jen; Gustin, Mae S.; Dent, Stephen; Eagles-Smith, Collin A.; Lutz, Michelle A; Wickland, Kimberly; Wang, Bronwen; Gray, John E.; Edwards, Grant; Krabbenhoft, David P.; Smith, David

    2016-01-01

    Mercury (Hg) emission and deposition can occur to and from soils, and are an important component of the global atmospheric Hg budget. This paper focuses on synthesizing existing surface-air Hg flux data collected throughout the Western North American region and is part of a series of geographically focused Hg synthesis projects. A database of existing Hg flux data collected using the dynamic flux chamber (DFC) approach from almost a thousand locations was created for the Western North America region. Statistical analysis was performed on the data to identify the important variables controlling Hg fluxes and to allow spatiotemporal scaling. The results indicated that most of the variability in soil-air Hg fluxes could be explained by variations in soil-Hg concentrations, solar radiation, and soil moisture. This analysis also identified that variations in DFC methodological approaches were detectable among the field studies, with the chamber material and sampling flushing flow rate influencing the magnitude of calculated emissions. The spatiotemporal scaling of soil-air Hg fluxes identified that the largest emissions occurred from irrigated agricultural landscapes in California. Vegetation was shown to have a large impact on surface-air Hg fluxes due to both a reduction in solar radiation reaching the soil as well as from direct uptake of Hg in foliage. Despite high soil Hg emissions from some forested and other heavily vegetated regions, the net ecosystem flux (soil flux + vegetation uptake) was low. Conversely, sparsely vegetated regions showed larger net ecosystem emissions, which were similar in magnitude to atmospheric Hg deposition (except for the Mediterranean California region where soil emissions were higher). The net ecosystem flux results highlight the important role of landscape characteristics in effecting the balance between Hg sequestration and (re-)emission to the atmosphere.

  10. Pressure enhancement associated with meridional flow in high-speed solar wind: possible evidence for an interplanetary magnetic flux rope

    Directory of Open Access Journals (Sweden)

    C.-Y. Tu

    1997-02-01

    Full Text Available A sizable total-pressure (magnetic pressure plus kinetic pressure enhancement was found within the high-speed wind stream observed by Helios 2 in 1976 near 0.3 AU. The proton density and temperature and the magnetic magnitude simultaneously increased for about 6 h. This pressure rise was associated with a comparatively large southward flow velocity component (with Vz ≈ –100 km · s–1 and magnetic-field rotation. The pressure enhancement was associated with unusual features in the electron distribution function. It shows a wide angular distribution of electron counting rates in the low-energy (57.8 eV channel, while previous to the enhancement it exhibits a wide angular distribution of electron count rate in the high-energy (112, 221 and 309 eV channels, perhaps indicating the mirroring of electrons in the converging field lines of the background magnetic field. These fluid and kinetic phenomena may be explained as resulting from an interplanetary magnetic flux rope which is not fully convected by the flow but moves against the background wind towards the Sun.

  11. Eddy Correlation Flux Measurement System Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind components and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.

  12. Assessment of the methods for determining net radiation at different time-scales of meteorological variables

    Directory of Open Access Journals (Sweden)

    Ni An

    2017-04-01

    Full Text Available When modeling the soil/atmosphere interaction, it is of paramount importance to determine the net radiation flux. There are two common calculation methods for this purpose. Method 1 relies on use of air temperature, while Method 2 relies on use of both air and soil temperatures. Nowadays, there has been no consensus on the application of these two methods. In this study, the half-hourly data of solar radiation recorded at an experimental embankment are used to calculate the net radiation and long-wave radiation at different time-scales (half-hourly, hourly, and daily using the two methods. The results show that, compared with Method 2 which has been widely adopted in agronomical, geotechnical and geo-environmental applications, Method 1 is more feasible for its simplicity and accuracy at shorter time-scale. Moreover, in case of longer time-scale, daily for instance, less variations of net radiation and long-wave radiation are obtained, suggesting that no detailed soil temperature variations can be obtained. In other words, shorter time-scales are preferred in determining net radiation flux.

  13. Remote sensing of soil radionuclide fluxes in a tropical ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Clegg, B.; Koranda, J.; Robinson, W.; Holladay, G.

    1980-11-06

    We are using a transponding geostationary satellite to collect surface environmental data to describe the fate of soil-borne radionuclides. The remote, former atomic testing grounds at the Eniwetok and Bikini Atolls present a difficult environment in which to collect continuous field data. Our land-based, solar-powered microprocessor and environmental data systems remotely acquire measurements of net and total solar radiation, rain, humidity, temperature, and soil-water potentials. For the past year, our water flux model predicts wet season plant transpiration rates nearly equal to the 6 to 7 mm/d evaporation pan rate, which decreases to 2 to 3 mm/d for the dry season. Radioisotopic analysis confirms the microclimate-estimated 1:3 to 1:20 soil to plant /sup 137/Cs dry matter concentration ratio. This ratio exacerbates the dose to man from intake of food plants. Nephelometer measurements of airborne particulates presently indicate a minimum respiratory radiological dose.

  14. Photosynthetic behavior, growth and essential oil production of Melissa officinalis L. cultivated under colored shade nets

    Directory of Open Access Journals (Sweden)

    Graziele C Oliveira

    2016-03-01

    Full Text Available The modulation of light is of importance during cultivation of medicinal plants to obtain desirable morphological and physiological changes associated with the maximum production of active principles. This study aimed to evaluate the effect of the light spectrum transmitted by colored shade nets on growth, essential oil production and photosynthetic behavior in plants of lemon balm (Melissa officinalis L. Plants were cultivated in pots for 4-mo under black, red, and blue nets with 50% shading, and full sunlight exposure. Biometric and anatomical variables, essential oil yield, global solar radiation, photon flux density, chlorophyll content, and gas exchange parameters were measured in M. officinalis leaves. The results showed that despite being considered a partial shade plant, this species is able to adapt to full sunlight conditions without increasing biomass production. The spectral changes provided by colored shade nets did not caused any noticeable change in leaf anatomy of M. officinalis. However, the use of blue net resulted in increments of 116% in plant height, 168% in leaf area, 42% in chlorophyll content and 30% in yield of essential oil in lemon balm plants. These plant's qualities make the use of blue net a cultivation practice suitable for commercial use.

  15. Heat and salt fluxes in the West Spitsbergen Current area in summer

    Directory of Open Access Journals (Sweden)

    Jan Piechura

    2002-09-01

    Full Text Available Fluxes of radiation, sensible and latent heat, and fluxes of heat and salt within the upper layer of the ocean were calculated on the basis of measurements carried out in the area of the Norwegian-Atlantic and West Spitsbergen Currents during summer 2000.      The sea surface radiation balance was calculated from direct measurements of downward and upward short-wave (solar radiation, the net radiation fluxes and sea surface temperature. The daily doses of radiation energy reaching and leaving the sea surface were also estimated.      To calculate the vertical heat fluxes in the atmospheric boundary layer the bulk parameterisation method was used. In most cases, the calculated heat fluxes were rather low, the average sensible heat flux was c. 10 W m-2, and the latent heat flux about one order of magnitude higher; this is what could be expected in summer. Salt fluxes to the air in the process of aerosol production are very small and can be neglected.      In summer the highest quantities of heat and salt are exchanged during mixing with surrounding waters.      According to our measurements, Atlantic Water on its northward course from about 70oN to 79oN loses about 100 TW of heat and 900 × 103 kg of salt. We thought it could be interesting to find out what happens to them. Some preliminary results of our investigation are presented here.

  16. Characteristics of absorbing aerosols during winter foggy period over the National Capital Region of Delhi: Impact of planetary boundary layer dynamics and solar radiation flux

    Science.gov (United States)

    Tyagi, S.; Tiwari, S.; Mishra, A.; Singh, S.; Hopke, Philip K.; Singh, Surender; Attri, S. D.

    2017-05-01

    Severe air pollution in the northern India coupled with the formation of secondary pollutants results in severe fog conditions during the winter. Black carbon (BC) and particulate matter (PM2.5) play a vital role within the planetary boundary layer (PBL) to degrade atmospheric visibility. These species were continuously monitored during the winter of 2014 in the National Capital Region (NCR) of Delhi. The average BC concentration was 8.0 ± 3.1 μg/m3 with the January mean (11.1 ± 5.4 μg/m3) approximately two times higher than February (5.9 ± 2.1 μg/m3). The average PM2.5 concentration was 137 ± 67 μg/m3 with monthly area-average maximum and minima in December and February, respectively. Higher concentrations of BC at 10:00 local standard time LST (8.5 μg/m3) and 22:00 LST (9.7 μg/m3) were consistently observed and assigned to morning and evening rush-hour traffic across Delhi. Daily average solar fluxes, varied between 17.9 and 220.7 W/m2 and had a negative correlation (r = - 0.5) with BC during fog episodes. Ventilation coefficient (VC) reduced from 'no fog' to fog phase over Palam Airport (PLM) (0.49) times and Hindon Airport (HND) (0.28) times and from fog to prolonged fog (> 14 h) phase over PLM (0.35) times and HND (0.41) times, respectively, indicating high pollution over the NCR of Delhi. Ground measurements showed that daily mean aerosol optical depth at 500 nm (AOD500) varied between 0.32 and 1.18 with mean AOD500 nm being highest during the prolonged fog (> 14 h) episodes (0.98 ± 0.08) consistent with variations in PM2.5 and BC. Angstrom exponent (α) and Angstrom turbidity coefficient (β) were found to be > 1 and 0.2, respectively, during fog showing the dominance of fine mode particles in the atmosphere.

  17. Solar radiation, phytoplankton pigments and the radiant heating of the equatorial Pacific warm pool

    Science.gov (United States)

    Siegel, David A.; Ohlmann, J. Carter; Washburn, Libe; Bidigare, Robert R.; Nosse, Craig T.; Fields, Erik; Zhou, Yimei

    1995-01-01

    Recent optical, physical, and biological oceanographic observations are used to assess the magnitude and variability of the penetrating flux of solar radiation through the mixed layer of the warm water pool (WWP) of the western equatorial Pacific Ocean. Typical values for the penetrative solar flux at the climatological mean mixed layer depth for the WWP (30 m) are approx. 23 W/sq m and are a large fraction of the climatological mean net air-sea heat flux (approx. 40 W/sq m). The penetrating solar flux can vary significantly on synoptic timescales. Following a sustained westerly wind burst in situ solar fluxes were reduced in response to a near tripling of mixed layer phytoplankton pigment concentrations. This results in a reduction in the penetrative flux at depth (5.6 W/sq m at 30 m) and corresponds to a biogeochemically mediated increase in the mixed layer radiant heating rate of 0.13 C per month. These observations demonstrate a significant role of biogeochemical processes on WWP thermal climate. We speculate that this biogeochemically mediated feedback process may play an important role in enhancing the rate at which the WWP climate system returns to normal conditions following a westerly wind burst event.

  18. Solar energy modulator

    Science.gov (United States)

    Hale, R. R. (Inventor); Mcdougal, A. R.

    1984-01-01

    A module is described with a receiver having a solar energy acceptance opening and supported by a mounting ring along the optic axis of a parabolic mirror in coaxial alignment for receiving solar energy from the mirror, and a solar flux modulator plate for varying the quantity of solar energy flux received by the acceptance opening of the module. The modulator plate is characterized by an annular, plate-like body, the internal diameter of which is equal to or slightly greater than the diameter of the solar energy acceptance opening of the receiver. Slave cylinders are connected to the modulator plate for supporting the plate for axial displacement along the axis of the mirror, therby shading the opening with respect to solar energy flux reflected from the surface of the mirror to the solar energy acceptance opening.

  19. NA-NET numerical analysis net

    Energy Technology Data Exchange (ETDEWEB)

    Dongarra, J. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science]|[Oak Ridge National Lab., TN (United States); Rosener, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host ``na-net.ornl.gov`` at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message ``send index`` to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user`s perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  20. NA-NET numerical analysis net

    Energy Technology Data Exchange (ETDEWEB)

    Dongarra, J. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science Oak Ridge National Lab., TN (United States)); Rosener, B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science)

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host na-net.ornl.gov'' at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message send index'' to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user's perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  1. UV sensitivity of planktonic net community production in ocean surface waters

    Science.gov (United States)

    Regaudie-de-Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-05-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we test the sensitivity of net community production (NCP) to UVB of planktonic communities in surface waters across contrasting regions of the ocean. We observed here that UVB radiation affects net plankton community production at the ocean surface, imposing a shift in NCP by, on average, 50% relative to the values measured when excluding partly UVB. Our results show that under full solar radiation, the metabolic balance shows the prevalence of net heterotrophic community production. The demonstration of an important effect of UVB radiation on NCP in surface waters presented here is of particular relevance in relation to the increased UVB radiation derived from the erosion of the stratospheric ozone layer. Our results encourage design future research to further our understanding of UVB effects on the metabolic balance of plankton communities.

  2. High-sensitive spectrometer of fast neutrons and the results of fast neutron background flux measurements at the Gallium-Germanium Solar Neutrino Experiment

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S

    2002-01-01

    The principle of operation, design, registration system and main characteristics of a fast neutron spectrometer are described. The spectrometer is intended for direct measurements of ultra low fluxes of fast neutrons. It is sensitive to neutron fluxes of 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11+-0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5+-2.1)x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4600 m of water equivalent was measured to be (7.3+-2.4)x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be <2.3x10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in 1.0-11.0 MeV energy range.

  3. ) Mold Fluxes

    Science.gov (United States)

    Seo, Myung-Duk; Shi, Cheng-Bin; Cho, Jung-Wook; Kim, Seon-Hyo

    2014-10-01

    The effects of basicity (CaO/SiO2), B2O3, and Li2O addition on the crystallization behaviors of lime-silica-based mold fluxes have been investigated by non-isothermal differential scanning calorimetry (DSC), field emission scanning electron microscopy, X-ray diffraction (XRD), and single hot thermocouple technique. It was found that the crystallization temperature of cuspidine increased with increasing the basicity of mold fluxes. The crystallization of wollastonite was suppressed with increasing the mold flux basicity due to the enhancement of cuspidine crystallization. The addition of B2O3 suppresses the crystallization of mold flux. The crystallization temperature of mold flux decreases with Li2O addition. The size of cuspidine increases, while the number of cuspidine decreases with increasing mold flux basicity. The morphology of cuspidine in mold fluxes with lower basicity is largely dendritic. The dendritic cuspidine in mold fluxes is composed of many fine cuspidine crystals. On the contrary, in mold fluxes with higher basicity, the cuspidine crystals are larger in size with mainly faceted morphology. The crystalline phase evolution was also calculated using a thermodynamic database, and compared with the experimental results determined by DSC and XRD. The results of thermodynamic calculation of crystalline phase formation are in accordance with the results determined by DSC and XRD.

  4. Physics of Magnetic Flux Ropes

    CERN Document Server

    Priest, E R; Lee, L C

    1990-01-01

    The American Geophysical Union Chapman Conference on the Physics of Magnetic Flux Ropes was held at the Hamilton Princess Hotel, Hamilton, Bermuda on March 27–31, 1989. Topics discussed ranged from solar flux ropes, such as photospheric flux tubes, coronal loops and prominences, to flux ropes in the solar wind, in planetary ionospheres, at the Earth's magnetopause, in the geomagnetic tail and deep in the Earth's magnetosphere. Papers presented at that conference form the nucleus of this book, but the book is more than just a proceedings of the conference. We have solicited articles from all interested in this topic. Thus, there is some material in the book not discussed at the conference. Even in the case of papers presented at the conference, there is generally a much more detailed and rigorous presentation than was possible in the time allowed by the oral and poster presentations.

  5. Urban Evapotranspiration and Carbon Dioxide Flux in Miami - Dade, Florida

    Science.gov (United States)

    Bernier, T.; Hopper, W.

    2010-12-01

    Atmospheric Carbon Dioxide (CO2) concentrations are leading indicators of secular climate change. With increasing awareness of the consequences of climate change, methods for monitoring this change are becoming more important daily. Of particular interest is the carbon dioxide exchange between natural and urban landscapes and the correlation of atmospheric CO2 concentrations. Monitoring Evapotranspiration (ET) is important for assessments of water availability for growing populations. ET is surprisingly understudied in the hydrologic cycle considering ET removes as much as 80 to over 100% of precipitation back into the atmosphere as water vapor. Lack of understanding in spatial and temporal ET estimates can limit the credibility of hydrologic water budgets designed to promote sustainable water use and resolve water-use conflicts. Eddy covariance (EC) methods are commonly used to estimate ET and CO2 fluxes. The EC platform consist of a (CSAT) 3-D Sonic Anemometer and a Li-Cor Open Path CO2/ H2O Analyzer. Measurements collected at 10 Hz create a very large data sets. A EC flux tower located in the Snapper Creek Well Field as part of a study to estimate ET for the Miami Dade County Water and Sewer project. Data has been collected from December 17, 2009 to August 30, 2010. QA/QC is performed with the EdiRe data processing software according to Ameri-flux protocols. ET estimates along with other data--latent-heat flux, sensible-heat flux, rainfall, air temperature, wind speed and direction, solar irradiance, net radiation, soil-heat flux and relative humidity--can be used to aid in the development of water management policies and regulations. Currently, many financial institutions have adopted an understanding about baseline environmental monitoring. The “Equator Principle” is an example of a voluntary standard for managing social and environmental risk in project financing and has changed the way in which projects are financed.

  6. SIMULATION OF HOMOLOGOUS AND CANNIBALISTIC CORONAL MASS EJECTIONS PRODUCED BY THE EMERGENCE OF A TWISTED FLUX ROPE INTO THE SOLAR CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Piyali; Fan, Yuhong, E-mail: mppiyali@ucar.edu [High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green Drive, Boulder, CO 80301 (United States)

    2013-11-20

    We report the first results of a magnetohydrodynamic simulation of the development of a homologous sequence of three coronal mass ejections (CMEs) and demonstrate their so-called cannibalistic behavior. These CMEs originate from the repeated formations and partial eruptions of kink unstable flux ropes as a result of continued emergence of a twisted flux rope across the lower boundary into a pre-existing coronal potential arcade field. The simulation shows that a CME erupting into the open magnetic field created by a preceding CME has a higher speed. The second of the three successive CMEs is cannibalistic, catching up and merging with the first into a single fast CME before exiting the domain. All the CMEs including the leading merged CME, attained speeds of about 1000 km s{sup –1} as they exit the domain. The reformation of a twisted flux rope after each CME eruption during the sustained flux emergence can naturally explain the X-ray observations of repeated reformations of sigmoids and ''sigmoid-under-cusp'' configurations at a low-coronal source of homologous CMEs.

  7. Professional Enterprise NET

    CERN Document Server

    Arking, Jon

    2010-01-01

    Comprehensive coverage to help experienced .NET developers create flexible, extensible enterprise application code If you're an experienced Microsoft .NET developer, you'll find in this book a road map to the latest enterprise development methodologies. It covers the tools you will use in addition to Visual Studio, including Spring.NET and nUnit, and applies to development with ASP.NET, C#, VB, Office (VBA), and database. You will find comprehensive coverage of the tools and practices that professional .NET developers need to master in order to build enterprise more flexible, testable, and ext

  8. Solar Activity and TECHNOSPHERE

    Science.gov (United States)

    Kuznetsov, V. D.

    2017-05-01

    A review of solar activity factors impacting on the near-Earth space and technosphere are given. Solar activity in the form of enhanced fluxes of hard electromagnetic and corpuscular radiation, solar wind streams and mass ejections is considered as a principal source of space weather creating the dangerous for the astronauts, satellites, International Space Station and for the ground technical systems. The examples of effects of solar activity on the space and ground technosphere are given.

  9. Contribution to the Solar Mean Magnetic Field from Different Solar Regions

    Science.gov (United States)

    Kutsenko, A. S.; Abramenko, V. I.; Yurchyshyn, V. B.

    2017-09-01

    Seven-year-long seeing-free observations of solar magnetic fields with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) were used to study the sources of the solar mean magnetic field, SMMF, defined as the net line-of-sight magnetic flux divided over the solar disk area. To evaluate the contribution of different regions to the SMMF, we separated all the pixels of each SDO/HMI magnetogram into three subsets: weak (BW), intermediate (BI), and strong (BS) fields. The BW component represents areas with magnetic flux densities below the chosen threshold; the BI component is mainly represented by network fields, remains of decayed active regions (ARs), and ephemeral regions. The BS component consists of magnetic elements in ARs. To derive the contribution of a subset to the total SMMF, the linear regression coefficients between the corresponding component and the SMMF were calculated. We found that i) when the threshold level of 30 Mx cm-2 is applied, the BI and BS components together contribute from 65% to 95% of the SMMF, while the fraction of the occupied area varies in a range of 2 - 6% of the disk area; ii) as the threshold magnitude is lowered to 6 Mx cm-2, the contribution from BI+BS grows to 98%, and the fraction of the occupied area reaches a value of about 40% of the solar disk. In summary, we found that regardless of the threshold level, only a small part of the solar disk area contributes to the SMMF. This means that the photospheric magnetic structure is an intermittent inherently porous medium, resembling a percolation cluster. These findings suggest that the long-standing concept that continuous vast unipolar areas on the solar surface are the source of the SMMF may need to be reconsidered.

  10. Astroparticle physics with solar neutrinos

    Science.gov (United States)

    NAKAHATA, Masayuki

    2011-01-01

    Solar neutrino experiments observed fluxes smaller than the expectations from the standard solar model. This discrepancy is known as the “solar neutrino problem”. Flux measurements by Super-Kamiokande and SNO have demonstrated that the solar neutrino problem is due to neutrino oscillations. Combining the results of all solar neutrino experiments, parameters for solar neutrino oscillations are obtained. Correcting for the effect of neutrino oscillations, the observed neutrino fluxes are consistent with the prediction from the standard solar model. In this article, results of solar neutrino experiments are reviewed with detailed descriptions of what Kamiokande and Super-Kamiokande have contributed to the history of astroparticle physics with solar neutrino measurements. PMID:21558758

  11. Astroparticle physics with solar neutrinos.

    Science.gov (United States)

    Nakahata, Masayuki

    2011-01-01

    Solar neutrino experiments observed fluxes smaller than the expectations from the standard solar model. This discrepancy is known as the "solar neutrino problem". Flux measurements by Super-Kamiokande and SNO have demonstrated that the solar neutrino problem is due to neutrino oscillations. Combining the results of all solar neutrino experiments, parameters for solar neutrino oscillations are obtained. Correcting for the effect of neutrino oscillations, the observed neutrino fluxes are consistent with the prediction from the standard solar model. In this article, results of solar neutrino experiments are reviewed with detailed descriptions of what Kamiokande and Super-Kamiokande have contributed to the history of astroparticle physics with solar neutrino measurements. (Communicated by Toshimitsu Yamazaki, M.J.A.).

  12. Determination of Energy Fluxes Over Agricultural Surfaces

    Directory of Open Access Journals (Sweden)

    Josefina Argete

    1994-12-01

    Full Text Available An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass and SEE = 81 Wm-2 over corn canopy. The calculated fluxes compared reasonably well with those obtained using the Penman equations.For an energy budget research with limited instrumentation, the aerodynamic method performed satisfactorily in estimating the daytime fluxes, when atmospheric conditions are fully convective, but failed when conditions were stably stratified as during nighttime.

  13. Solar Chameleons

    CERN Document Server

    Brax, Philippe

    2010-01-01

    We analyse the creation of chameleons deep inside the sun and their subsequent conversion to photons near the magnetised surface of the sun. We find that the spectrum of the regenerated photons lies in the soft X-ray region, hence addressing the solar corona problem. Moreover, these back-converted photons originating from chameleons have an intrinsic difference with regenerated photons from axions: their relative polarisations are mutually orthogonal before Compton interacting with the surrounding plasma. Depending on the photon-chameleon coupling and working in the strong coupling regime of the chameleons to matter, we find that the induced photon flux, when regenerated resonantly with the surrounding plasma, coincides with the solar flux within the soft X-ray energy range. Moreover, using the soft X-ray solar flux as a prior, we find that with a strong enough photon-chameleon coupling the chameleons emitted by the sun could lead to a regenerated photon flux in the CAST pipes, which could be within the reach...

  14. Gaseous elemental mercury (GEM) fluxes over canopy of two typical subtropical forests in south China

    Science.gov (United States)

    Yu, Qian; Luo, Yao; Wang, Shuxiao; Wang, Zhiqi; Hao, Jiming; Duan, Lei

    2018-01-01

    Mercury (Hg) exchange between forests and the atmosphere plays an important role in global Hg cycling. The present estimate of global emission of Hg from natural source has large uncertainty, partly due to the lack of chronical and valid field data, particularly for terrestrial surfaces in China, the most important contributor to global atmospheric Hg. In this study, the micrometeorological method (MM) was used to continuously observe gaseous elemental mercury (GEM) fluxes over forest canopy at a mildly polluted site (Qianyanzhou, QYZ) and a moderately polluted site (Huitong, HT, near a large Hg mine) in subtropical south China for a full year from January to December in 2014. The GEM flux measurements over forest canopy in QYZ and HT showed net emission with annual average values of 6.67 and 0.30 ng m-2 h-1, respectively. Daily variations of GEM fluxes showed an increasing emission with the increasing air temperature and solar radiation in the daytime to a peak at 13:00, and decreasing emission thereafter, even as a GEM sink or balance at night. High temperature and low air Hg concentration resulted in the high Hg emission in summer. Low temperature in winter and Hg absorption by plant in spring resulted in low Hg emission, or even adsorption in the two seasons. GEM fluxes were positively correlated with air temperature, soil temperature, wind speed, and solar radiation, while it is negatively correlated with air humidity and atmospheric GEM concentration. The lower emission fluxes of GEM at the moderately polluted site (HT) when compared with that in the mildly polluted site (QYZ) may result from a much higher adsorption fluxes at night in spite of a similar or higher emission fluxes during daytime. This shows that the higher atmospheric GEM concentration at HT restricted the forest GEM emission. Great attention should be paid to forests as a crucial increasing Hg emission source with the decreasing atmospheric GEM concentration in polluted areas because of Hg

  15. Where is the Open Flux?

    Science.gov (United States)

    Linker, Jon A.; Downs, Cooper; Caplan, Ronald M.; Lionello, Roberto; Mikic, Zoran; Riley, Pete; Henney, Carl John; Arge, Charles; Owens, Matthew

    2017-08-01

    The Sun’s magnetic field has been observed in the photosphere from ground- and space-based observatories for many years. Global maps of the solar magnetic field based on full disk magnetograms (either built up over a solar rotation, or evolved using flux transport models) are commonly used as boundary conditions for coronal and solar wind models. Maps from different observatories typically agree qualitatively but often disagree quantitatively. Estimation of the coronal/solar wind physics can range from potential field source surface (PFSS) models with empirical prescriptions to magnetohydrodynamic (MHD) models with realistic energy transport and sub-grid scale descriptions of heating and acceleration. Two primary observational constraints on the models are (1) The open field regions in the model should approximately correspond to coronal holes observed in emission, and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. We have investigated the July 2010 time period, using PFSS and MHD models computed using several available magnetic maps, coronal hole boundaries detected from STEREO and SDO EUV observations, and estimates of the interplanetary magnetic flux from in situ ACE measurements. We show that for all the model/map combinations, models that agree for (1) underestimate the interplanetary magnetic flux, or, conversely, for models to match (2), the modeled open field regions are larger than observed coronal holes. Alternatively, we estimate the open magnetic flux entirely from solar observations by combining detected coronal hole boundaries with observatory synoptic magnetic maps, and show that this method also underestimates the interplanetary magnetic flux. We discuss possible resolutions.Research supported by NASA, AFOSR, and NSF.

  16. Electron Energy Spectra, Fluxes, and Day-Night Asymmetries of $^{8}$B Solar Neutrinos from the 391-Day Salt Phase SNO Data Set

    CERN Document Server

    Aharmim, B; Anthony, A E; Beier, E W; Bellerive, A; Bergevin, M; Biller, S D; Boger, J; Boulay, M G; Bowler, M G; Bullard, T V; Chan, Y D; Chen, M; Chen, X; Cleveland, B T; Cox, G A; Currat, C A; Dai, X; Dalnoki-Veress, F; Deng, H; Doe, P J; Dosanjh, R S; Doucas, G; Duba, C A; Duncan, F A; Dunford, M; Dunmore, J A; Earle, E D; Elliott, S R; Evans, H C; Ewan, G T; Farine, J; Fergani, H; Fleurot, F; Formaggio, J A; Frame, K; Frati, W; Fulsom, B G; Gagnon, N; Graham, K; Grant, D R; Hahn, R L; Hall, J C; Hallin, A L; Hallman, E D; Handler, W B; Hargrove, C K; Harvey, P J; Hazama, R; Heeger, K M; Heelan, L; Heintzelman, W J; Heise, J; Helmer, R L; Hemingway, R J; Hime, A; Howard, C; Howe, M A; Huang, M; Jagam, P; Jelley, N A; Klein, J R; Kormos, L L; Kos, M S; Krüger, A; Kraus, C V; Krauss, C B; Krumins, A V; Kutter, T; Kyba, C C M; Labranche, H; Lange, R; Law, J; Lawson, I T; Lesko, K T; Leslie, J R; Levine, I; Loach, J C; Luoma, S; MacLellan, R; Majerus, S; Mak, H B; Maneira, J; Marino, A D; McCauley, N; McDonald, A B; McGee, S; McGregor, G; Miin, C; Miknaitis, K K S; Moffat, B A; Nally, C W; Neubauer, M S; Nickel, B G; Noble, A J; Norman, E B; Oblath, N S; Okada, C E; Ollerhead, R W; Orrell, J L; Oser, S M; Ouellet, C V; Peeters, S J M; Poon, A W P; Rielage, K; Robertson, B C; Robertson, R G H; Rollin, E; Rosendahl, S S E; Rusu, V L; Schwendener, M H; Seibert, S R; Simard, O; Simpson, J J; Sims, C J; Sinclair, D; Skensved, P; Smith, M W E; Starinsky, N; Stokstad, R G; Stonehill, L C; Tafirout, R; Takeuchi, Y; Tesic, G; Thomson, M; Thorman, M; Tsui, T; Van Berg, R; Van de Water, R G; Virtue, C J; Wall, B L; Waller, D; Waltham, C E; Wan Chan Tseung, H; Wark, D L; Wendland, J; West, N; Wilkerson, J F; Wilson, J R; Wittich, P; Wouters, J M; Wright, A; Yeh, M; Zuber, K

    2005-01-01

    Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the D$_2$O target. The addition of salt enhanced the signal from neutron capture, as compared to the pure D$_2$O detector. By making a statistical separation of charged-current events from other types based on event-isotropy criteria, the effective electron recoil energy spectrum has been extracted. In units of $ 10^6$ cm$^{-2}$ s$^{-1}$, the total flux of active-flavor neutrinos from $^8$B decay in the Sun is found to be $4.94^{+0.21}_{-0.21}{(stat)}^{+0.38}_{-0.34}{(syst)}$ and the integral flux of electron neutrinos for an undistorted $^8$B spectrum is $1.68^{+0.06}_{-0.06}{(stat)}^{+0.08}_{-0.09}{(syst)}$; the signal from ($\

  17. Solar neutrinos; Les neutrinos solaires

    Energy Technology Data Exchange (ETDEWEB)

    Schatzman, E. [Observatoire de Paris, 92 - Meudon (France)

    1998-07-01

    The experimental determinations of the solar neutrino flux (Homestake Goldmine GALLEX and SAGE, Kamiokande and Super-Kamiokande) show a deficit compared to what is predicted by the standard solar model. The difference between the experimental data and the theoretical results of the standard solar model can be due either to defects in the solar model or to neutrino properties. Nevertheless the neutrino flux given by Kamiokande experiment agrees with some of the solar models. The future Sudbury experiment based on the dissociation of heavy water by solar neutrinos will shed light on the debated question of neutrino mass. (author)

  18. Turbulent flux variability and energy balance closure in the TERENO prealpine observatory: a hydrometeorological data analysis

    Science.gov (United States)

    Soltani, Mohsen; Mauder, Matthias; Laux, Patrick; Kunstmann, Harald

    2017-07-01

    The temporal multiscale variability of the surface heat fluxes is assessed by the analysis of the turbulent heat and moisture fluxes using the eddy covariance (EC) technique at the TERrestrial ENvironmental Observatories (TERENO) prealpine region. The fast and slow response variables from three EC sites located at Fendt, Rottenbuch, and Graswang are gathered for the period of 2013 to 2014. Here, the main goals are to characterize the multiscale variations and drivers of the turbulent fluxes, as well as to quantify the energy balance closure (EBC) and analyze the possible reasons for the lack of EBC at the EC sites. To achieve these goals, we conducted a principal component analysis (PCA) and a climatological turbulent flux footprint analysis. The results show significant differences in the mean diurnal variations of the sensible heat (H) and latent heat (LE) fluxes, because of variations in the solar radiation, precipitation patterns, soil moisture, and the vegetation fraction throughout the year. LE was the main consumer of net radiation. Based on the first principal component (PC1), the radiation and temperature components with a total mean contribution of 29.5 and 41.3%, respectively, were found to be the main drivers of the turbulent fluxes at the study EC sites. A general lack of EBC is observed, where the energy imbalance values amount 35, 44, and 35% at the Fendt, Rottenbuch, and Graswang sites, respectively. An average energy balance ratio (EBR) of 0.65 is obtained in the region. The best closure occurred in the afternoon peaking shortly before sunset with a different pattern and intensity between the study sites. The size and shape of the annual mean half-hourly turbulent flux footprint climatology was analyzed. On average, 80% of the flux footprint was emitted from a radius of approximately 250 m around the EC stations. Moreover, the overall shape of the flux footprints was in good agreement with the prevailing wind direction for all three TERENO EC sites.

  19. Surface renewal method for estimating sensible heat flux | Mengistu ...

    African Journals Online (AJOL)

    For short canopies, latent energy flux may be estimated using a shortened surface energy balance from measurements of sensible and soil heat flux and the net irradiance at the surface. The surface renewal (SR) method for estimating sensible heat, latent energy, and other scalar fluxes has the advantage over other ...

  20. WaveNet

    Science.gov (United States)

    2015-10-30

    Coastal Inlets Research Program WaveNet WaveNet is a web-based, Graphical-User-Interface ( GUI ) data management tool developed for Corps coastal...generates tabular and graphical information for project planning and design documents. The WaveNet is a web-based GUI designed to provide users with a...data from different sources, and employs a combination of Fortran, Python and Matlab codes to process and analyze data for USACE applications

  1. Carbon balance and energy fluxes of a Mediterranean crop

    Directory of Open Access Journals (Sweden)

    Simona Consoli

    2013-09-01

    Full Text Available This paper is based on the analysis of a long-term mass (carbon dioxide, water vapour and energy (solar radiation balance monitoring programme carried out during years 2010 and 2012 in an irrigated orange orchard in Sicily, using the Eddy Covariance (EC method. Orange (Citrus sinensis L. is one of the main fruit crops worldwide and its evergreen orchard may have a great potential for carbon sequestration, but few data are currently available. In the study, the role of the orchard system in sequestering atmospheric CO2 was analyzed, thus contributing to assess the carbon balance of the specie in the specific environment.Vertical energy fluxes of net radiation, soil heat, sensible heat and latent heat fluxes were measured at orchard scale by EC. Evapotranspiration (ET values were compared with upscaled transpiration data determined by the sap flow heat pulse technique, evidencing the degree of correspondence between instantaneous transpirational flux at tree level and the micrometeorological measurement of ET at orchard level.

  2. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...... use of CP-nets — because it means that the function representation and the translations (which are a bit mathematically complex) no longer are parts of the basic definition of CP-nets. Instead they are parts of the invariant method (which anyway demands considerable mathematical skills...

  3. Game Coloured Petri Nets

    DEFF Research Database (Denmark)

    Westergaard, Michael

    2006-01-01

    This paper introduces the notion of game coloured Petri nets. This allows the modeler to explicitly model what parts of the model comprise the modeled system and what parts are the environment of the modeled system. We give the formal definition of game coloured Petri nets, a means of reachability...... analysis of this net class, and an application of game coloured Petri nets to automatically generate easy-to-understand visualizations of the model by exploiting the knowledge that some parts of the model are not interesting from a visualization perspective (i.e. they are part of the environment...

  4. Programming NET Web Services

    CERN Document Server

    Ferrara, Alex

    2007-01-01

    Web services are poised to become a key technology for a wide range of Internet-enabled applications, spanning everything from straight B2B systems to mobile devices and proprietary in-house software. While there are several tools and platforms that can be used for building web services, developers are finding a powerful tool in Microsoft's .NET Framework and Visual Studio .NET. Designed from scratch to support the development of web services, the .NET Framework simplifies the process--programmers find that tasks that took an hour using the SOAP Toolkit take just minutes. Programming .NET

  5. Annotating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    -net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... a method which makes it possible to associate auxiliary information, called annotations, with tokens without modifying the colour sets of the CP-net. Annotations are pieces of information that are not essential for determining the behaviour of the system being modelled, but are rather added to support...

  6. Net ecosystem carbon exchange of a dry temperate eucalypt forest

    Science.gov (United States)

    Hinko-Najera, Nina; Isaac, Peter; Beringer, Jason; van Gorsel, Eva; Ewenz, Cacilia; McHugh, Ian; Exbrayat, Jean-François; Livesley, Stephen J.; Arndt, Stefan K.

    2017-08-01

    Forest ecosystems play a crucial role in the global carbon cycle by sequestering a considerable fraction of anthropogenic CO2, thereby contributing to climate change mitigation. However, there is a gap in our understanding about the carbon dynamics of eucalypt (broadleaf evergreen) forests in temperate climates, which might differ from temperate evergreen coniferous or deciduous broadleaved forests given their fundamental differences in physiology, phenology and growth dynamics. To address this gap we undertook a 3-year study (2010-2012) of eddy covariance measurements in a dry temperate eucalypt forest in southeastern Australia. We determined the annual net carbon balance and investigated the temporal (seasonal and inter-annual) variability in and environmental controls of net ecosystem carbon exchange (NEE), gross primary productivity (GPP) and ecosystem respiration (ER). The forest was a large and constant carbon sink throughout the study period, even in winter, with an overall mean NEE of -1234 ± 109 (SE) g C m-2 yr-1. Estimated annual ER was similar for 2010 and 2011 but decreased in 2012 ranging from 1603 to 1346 g C m-2 yr-1, whereas GPP showed no significant inter-annual variability, with a mean annual estimate of 2728 ± 39 g C m-2 yr-1. All ecosystem carbon fluxes had a pronounced seasonality, with GPP being greatest during spring and summer and ER being highest during summer, whereas peaks in NEE occurred in early spring and again in summer. High NEE in spring was likely caused by a delayed increase in ER due to low temperatures. A strong seasonal pattern in environmental controls of daytime and night-time NEE was revealed. Daytime NEE was equally explained by incoming solar radiation and air temperature, whereas air temperature was the main environmental driver of night-time NEE. The forest experienced unusual above-average annual rainfall during the first 2 years of this 3-year period so that soil water content remained relatively high and the forest

  7. Net ecosystem carbon exchange of a dry temperate eucalypt forest

    Directory of Open Access Journals (Sweden)

    N. Hinko-Najera

    2017-08-01

    Full Text Available Forest ecosystems play a crucial role in the global carbon cycle by sequestering a considerable fraction of anthropogenic CO2, thereby contributing to climate change mitigation. However, there is a gap in our understanding about the carbon dynamics of eucalypt (broadleaf evergreen forests in temperate climates, which might differ from temperate evergreen coniferous or deciduous broadleaved forests given their fundamental differences in physiology, phenology and growth dynamics. To address this gap we undertook a 3-year study (2010–2012 of eddy covariance measurements in a dry temperate eucalypt forest in southeastern Australia. We determined the annual net carbon balance and investigated the temporal (seasonal and inter-annual variability in and environmental controls of net ecosystem carbon exchange (NEE, gross primary productivity (GPP and ecosystem respiration (ER. The forest was a large and constant carbon sink throughout the study period, even in winter, with an overall mean NEE of −1234 ± 109 (SE g C m−2 yr−1. Estimated annual ER was similar for 2010 and 2011 but decreased in 2012 ranging from 1603 to 1346 g C m−2 yr−1, whereas GPP showed no significant inter-annual variability, with a mean annual estimate of 2728 ± 39 g C m−2 yr−1. All ecosystem carbon fluxes had a pronounced seasonality, with GPP being greatest during spring and summer and ER being highest during summer, whereas peaks in NEE occurred in early spring and again in summer. High NEE in spring was likely caused by a delayed increase in ER due to low temperatures. A strong seasonal pattern in environmental controls of daytime and night-time NEE was revealed. Daytime NEE was equally explained by incoming solar radiation and air temperature, whereas air temperature was the main environmental driver of night-time NEE. The forest experienced unusual above-average annual rainfall during the first 2 years of this 3-year period so

  8. Initiation of CMEs by Magnetic Flux Emergence

    Indian Academy of Sciences (India)

    Keywords. Sun: corona, coronal mass ejections; magnetic fields; magnetohydrodynamics; flux emergence. Abstract. The initiation of solar Coronal Mass Ejections (CMEs) is studied in the framework of numerical magnetohydrodynamics (MHD). The initial CME model includes a magnetic flux rope in spherical, axisymmetric ...

  9. Net zero water

    CSIR Research Space (South Africa)

    Lindeque, M

    2013-01-01

    Full Text Available Is it possible to develop a building that uses a net zero amount of water? In recent years it has become evident that it is possible to have buildings that use a net zero amount of electricity. This is possible when the building is taken off...

  10. Kunstige neurale net

    DEFF Research Database (Denmark)

    Hørning, Annette

    1994-01-01

    Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse.......Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse....

  11. Solar monopoles and terrestrial neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Frieman, J.

    1988-04-01

    Magnetic monopoles captured in the core of the sun may give rise to a substantial flux of energetic neutrinos by catalyzing the decay of solar hydrogen. We discuss the expected neutrino flux in underground detectors under different assumptions about solar interior conditions. Although a monopole flux as low as F/sub M/ /approximately/ 10/sup /minus/24/ cm/sup /minus/2/ sec/sup /minus/1/ sr/sup /minus/1/ could give rise to a neutrino flux above atmospheric background, due to M/bar M/ annihilation, this does not translate into a reliable monopole flux bound stronger than the Parker limit. 8 refs., 1 fig.

  12. Slowly varying component of extreme ultraviolet solar radiation and its relation to solar radio radiation

    Science.gov (United States)

    Chapman, R. D.; Neupert, W. M.

    1974-01-01

    A study of the correlations between solar EUV line fluxes and solar radio fluxes has been carried out. A calibration for the Goddard Space Flight Center EUV spectrum is suggested. The results are used to obtain an equation for the absolute EUV flux for several lines in the 150- to 400-A region and the total flux of 81 intense lines in the region, the 2800-MHz radio flux being used as independent variable.

  13. Flux measurements of energy and trace gases in urban Houston, Texas

    Science.gov (United States)

    Boedeker, I.; Schade, G. W.; Adams, S.; Park, C.

    2008-12-01

    We describe the setup and some first year results of a new flux measurements tower in an urban area. An existing radio communications tower 4 km north of downtown Houston was equipped with micrometeorological instrumentation and trace gas sampling lines in spring 2007. Wind speed, temperature and relative humidity are recorded at five levels between 12 and 60 m above ground; 3-D wind speed measurements, solar and net radiances, and trace gas sampling are established from the 60 m level. A closed path IRGA is used for CO2 and water vapor fluxes, and independent instrumentation for criteria pollutant and VOC fluxes. Two CSI data loggers and software control the measurements, and EdiRe software is used to analyze turbulence data and compute fluxes. A project description is provided at http://atmo.tamu.edu/yellowcabtower. Surface properties as calculated from the gradient measurements show the site to be surprisingly uniform, with displacement heights between 5 and 9 m and roughness lengths between 0.4 and 0.7 m, despite urban heterogeneity. The latter is investigated through visible/near IR orthoimagery and LIDAR data, which are incorporated into a local GIS. Net radiation was also only marginally affected by surface heterogeneity. At this urban location it is balanced by roughly equal amounts of sensible heat, latent heat, and storage fluxes. Latent heat flux, however, is smaller outside the growing season, with an equivalent increase in winter storage fluxes, as expected. Significant differences are also observed with direction during summer, showing decreased Bowen ratios and lower CO2 emissions from sectors with a larger urban tree canopy cover in the footprint. The largely mature, dominantly oak urban canopy cover alleviates approximately 100 W m- 2 during typical summer days. On the other hand, anthropogenic CO2 emissions dominate over photosynthetic uptake all year round. Measured carbon fluxes peak during morning rush-hour traffic, especially when increasing

  14. The Solar Cycle

    Directory of Open Access Journals (Sweden)

    David H. Hathaway

    2010-03-01

    Full Text Available The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. We examine a number of other solar activity indicators including the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores that vary in association with the sunspots. We examine the characteristics of individual solar cycles including their maxima and minima, cycle periods and amplitudes, cycle shape, and the nature of active latitudes, hemispheres, and longitudes. We examine long-term variability including the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev–Ohl Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double peaked maxima. We conclude with an examination of prediction techniques for the solar cycle.

  15. Pro NET Best Practices

    CERN Document Server

    Ritchie, Stephen D

    2011-01-01

    Pro .NET Best Practices is a practical reference to the best practices that you can apply to your .NET projects today. You will learn standards, techniques, and conventions that are sharply focused, realistic and helpful for achieving results, steering clear of unproven, idealistic, and impractical recommendations. Pro .NET Best Practices covers a broad range of practices and principles that development experts agree are the right ways to develop software, which includes continuous integration, automated testing, automated deployment, and code analysis. Whether the solution is from a free and

  16. Getting to Net Zero

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

  17. Instant Lucene.NET

    CERN Document Server

    Heydt, Michael

    2013-01-01

    Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. A step-by-step guide that helps you to index, search, and retrieve unstructured data with the help of Lucene.NET.Instant Lucene.NET How-to is essential for developers new to Lucene and Lucene.NET who are looking to get an immediate foundational understanding of how to use the library in their application. It's assumed you have programming experience in C# already, but not that you have experience with search techniques such as information retrieval theory (although there will be a l

  18. Methods and systems for concentrated solar power

    Science.gov (United States)

    Ma, Zhiwen

    2016-05-24

    Embodiments described herein relate to a method of producing energy from concentrated solar flux. The method includes dropping granular solid particles through a solar flux receiver configured to transfer energy from concentrated solar flux incident on the solar flux receiver to the granular solid particles as heat. The method also includes fluidizing the granular solid particles from the solar flux receiver to produce a gas-solid fluid. The gas-solid fluid is passed through a heat exchanger to transfer heat from the solid particles in the gas-solid fluid to a working fluid. The granular solid particles are extracted from the gas-solid fluid such that the granular solid particles can be dropped through the solar flux receiver again.

  19. PhysioNet

    Data.gov (United States)

    U.S. Department of Health & Human Services — The PhysioNet Resource is intended to stimulate current research and new investigations in the study of complex biomedical and physiologic signals. It offers free...

  20. NetSig

    DEFF Research Database (Denmark)

    Horn, Heiko; Lawrence, Michael S; Chouinard, Candace R

    2018-01-01

    Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to validate at scale, and their predictive value remains unclear. We developed a robust statistic (Net......Sig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that Net......Sig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified...

  1. Solar Wind Variation with the Cycle I. S. Veselovsky,* A. V. Dmitriev ...

    Indian Academy of Sciences (India)

    tribpo

    Solar wind, energy and mass flux densities during the 20–23 solar cycles. (a) sunspot numbers; (b) solar wind energy flux density St;(c) solar wind mass flux density j. cycles with time scales from days to tens of years. The results of this investigation. (Veselovsky et al. 2000b) show a large manifold of the regular and irregular ...

  2. TideNet

    Science.gov (United States)

    2015-10-30

    query tide data sources in a desired geographic region of USA and its territories (Figure 1). Users can select a tide data source through the Google Map ...select data sources according to the desired geographic region. It uses the Google Map interface to display data from different sources. Recent...Coastal Inlets Research Program TideNet The TideNet is a web-based Graphical User Interface (GUI) that provides users with GIS mapping tools to

  3. Building Neural Net Software

    OpenAIRE

    Neto, João Pedro; Costa, José Félix

    1999-01-01

    In a recent paper [Neto et al. 97] we showed that programming languages can be translated on recurrent (analog, rational weighted) neural nets. The goal was not efficiency but simplicity. Indeed we used a number-theoretic approach to machine programming, where (integer) numbers were coded in a unary fashion, introducing a exponential slow down in the computations, with respect to a two-symbol tape Turing machine. Implementation of programming languages in neural nets turns to be not only theo...

  4. Interaction Nets in Russian

    OpenAIRE

    Salikhmetov, Anton

    2013-01-01

    Draft translation to Russian of Chapter 7, Interaction-Based Models of Computation, from Models of Computation: An Introduction to Computability Theory by Maribel Fernandez. "In this chapter, we study interaction nets, a model of computation that can be seen as a representative of a class of models based on the notion of 'computation as interaction'. Interaction nets are a graphical model of computation devised by Yves Lafont in 1990 as a generalisation of the proof structures of linear logic...

  5. Programming NET 35

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Bestselling author Jesse Liberty and industry expert Alex Horovitz uncover the common threads that unite the .NET 3.5 technologies, so you can benefit from the best practices and architectural patterns baked into the new Microsoft frameworks. The book offers a Grand Tour" of .NET 3.5 that describes how the principal technologies can be used together, with Ajax, to build modern n-tier and service-oriented applications. "

  6. Effect of environmental conditions on the relationship between solar-induced fluorescence and gross primary productivity at an OzFlux grassland site

    Science.gov (United States)

    Verma, Manish; Schimel, David; Evans, Bradley; Frankenberg, Christian; Beringer, Jason; Drewry, Darren T.; Magney, Troy; Marang, Ian; Hutley, Lindsay; Moore, Caitlin; Eldering, Annmarie

    2017-03-01

    Recent studies have utilized coarse spatial and temporal resolution remotely sensed solar-induced fluorescence (SIF) for modeling terrestrial gross primary productivity (GPP) at regional scales. Although these studies have demonstrated the potential of SIF, there have been concerns about the ecophysiological basis of the relationship between SIF and GPP in different environmental conditions. Launched in 2014, the Orbiting Carbon Observatory-2 (OCO-2) has enabled fine-scale (1.3 by 2.5 km) retrievals of SIF that are comparable with measurements recorded at eddy covariance towers. In this study, we examine the effect of environmental conditions on the relationship of OCO-2 SIF with tower GPP over the course of a growing season at a well-characterized natural grassland site. Combining OCO-2 SIF and eddy covariance tower data with a canopy radiative transfer and an ecosystem model, we also assess the potential of OCO-2 SIF to constrain the estimates of Vcmax, one of the most important parameters in ecosystem models. Based on the results, we suggest that although environmental conditions play a role in determining the nature of relationship between SIF and GPP, overall, the linear relationship is more robust at ecosystem scale than the theory based on leaf-level processes might suggest. Our study also shows that the ability of SIF to constrain Vcmax is weak at the selected site.

  7. Solar Power System Design for the Solar Probe+ Mission

    Science.gov (United States)

    Landis, Geoffrey A.; Schmitz, Paul C.; Kinnison, James; Fraeman, Martin; Roufberg, Lew; Vernon, Steve; Wirzburger, Melissa

    2008-01-01

    Solar Probe+ is an ambitious mission proposed to the solar corona, designed to make a perihelion approach of 9 solar radii from the surface of the sun. The high temperature, high solar flux environment makes this mission a significant challenge for power system design. This paper summarizes the power system conceptual design for the solar probe mission. Power supplies considered included nuclear, solar thermoelectric generation, solar dynamic generation using Stirling engines, and solar photovoltaic generation. The solar probe mission ranges from a starting distance from the sun of 1 AU, to a minimum distance of about 9.5 solar radii, or 0.044 AU, from the center of the sun. During the mission, the solar intensity ranges from one to about 510 times AM0. This requires power systems that can operate over nearly three orders of magnitude of incident intensity.

  8. Development of net cage acoustic alarm system

    Science.gov (United States)

    Hong, Shih-Wei; Wei, Ruey-Chang

    2004-05-01

    In recent years, the fishery production has been drastically decreased in Taiwan, mainly due to overfishing and coast pollution; therefore, fishermen and corporations are encouraged by government to invest in ocean net cage aquaculture. However, the high-price fishes in the net cage are often coveted, so incidences of fish stealing and net cage breaking were found occasionally, which cause great economical loss. Security guards or a visual monitoring system has limited effect, especially in the night when these intrusions occur. This study is based on acoustic measure to build a net cage alarm system, which includes the sonobuoy and monitor station on land. The sonobuoy is a passive sonar that collects the sounds near the net cage and transmits the suspected signal to the monitor station. The signals are analyzed by the control program on the personal computer in the monitor station, and the alarms at different stages could be activated by the sound levels and durations of the analyzed data. To insure long hours of surveillance, a solar panel is applied to charge the battery, and a photodetector is used to activate the system.

  9. Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region

    Science.gov (United States)

    Moreira, Demerval S.; Longo, Karla M.; Freitas, Saulo R.; Yamasoe, Marcia A.; Mercado, Lina M.; Rosário, Nilton E.; Gloor, Emauel; Viana, Rosane S. M.; Miller, John B.; Gatti, Luciana V.; Wiedemann, Kenia T.; Domingues, Lucas K. G.; Correia, Caio C. S.

    2017-12-01

    Every year, a dense smoke haze covers a large portion of South America originating from fires in the Amazon Basin and central parts of Brazil during the dry biomass burning season between August and October. Over a large portion of South America, the average aerosol optical depth at 550 nm exceeds 1.0 during the fire season, while the background value during the rainy season is below 0.2. Biomass burning aerosol particles increase scattering and absorption of the incident solar radiation. The regional-scale aerosol layer reduces the amount of solar energy reaching the surface, cools the near-surface air, and increases the diffuse radiation fraction over a large disturbed area of the Amazon rainforest. These factors affect the energy and CO2 fluxes at the surface. In this work, we applied a fully integrated atmospheric model to assess the impact of biomass burning aerosols in CO2 fluxes in the Amazon region during 2010. We address the effects of the attenuation of global solar radiation and the enhancement of the diffuse solar radiation flux inside the vegetation canopy. Our results indicate that biomass burning aerosols led to increases of about 27 % in the gross primary productivity of Amazonia and 10 % in plant respiration as well as a decline in soil respiration of 3 %. Consequently, in our model Amazonia became a net carbon sink; net ecosystem exchange during September 2010 dropped from +101 to -104 TgC when the aerosol effects are considered, mainly due to the aerosol diffuse radiation effect. For the forest biome, our results point to a dominance of the diffuse radiation effect on CO2 fluxes, reaching a balance of 50-50 % between the diffuse and direct aerosol effects for high aerosol loads. For C3 grasses and savanna (cerrado), as expected, the contribution of the diffuse radiation effect is much lower, tending to zero with the increase in aerosol load. Taking all biomes together, our model shows the Amazon during the dry season, in the presence of high

  10. Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region

    Directory of Open Access Journals (Sweden)

    D. S. Moreira

    2017-12-01

    Full Text Available Every year, a dense smoke haze covers a large portion of South America originating from fires in the Amazon Basin and central parts of Brazil during the dry biomass burning season between August and October. Over a large portion of South America, the average aerosol optical depth at 550 nm exceeds 1.0 during the fire season, while the background value during the rainy season is below 0.2. Biomass burning aerosol particles increase scattering and absorption of the incident solar radiation. The regional-scale aerosol layer reduces the amount of solar energy reaching the surface, cools the near-surface air, and increases the diffuse radiation fraction over a large disturbed area of the Amazon rainforest. These factors affect the energy and CO2 fluxes at the surface. In this work, we applied a fully integrated atmospheric model to assess the impact of biomass burning aerosols in CO2 fluxes in the Amazon region during 2010. We address the effects of the attenuation of global solar radiation and the enhancement of the diffuse solar radiation flux inside the vegetation canopy. Our results indicate that biomass burning aerosols led to increases of about 27 % in the gross primary productivity of Amazonia and 10 % in plant respiration as well as a decline in soil respiration of 3 %. Consequently, in our model Amazonia became a net carbon sink; net ecosystem exchange during September 2010 dropped from +101 to −104 TgC when the aerosol effects are considered, mainly due to the aerosol diffuse radiation effect. For the forest biome, our results point to a dominance of the diffuse radiation effect on CO2 fluxes, reaching a balance of 50–50 % between the diffuse and direct aerosol effects for high aerosol loads. For C3 grasses and savanna (cerrado, as expected, the contribution of the diffuse radiation effect is much lower, tending to zero with the increase in aerosol load. Taking all biomes together, our model shows the Amazon during the dry

  11. La plataforma .NET

    OpenAIRE

    Fornas Estrada, Miquel

    2008-01-01

    L'aparició de la plataforma .NET Framework ha suposat un canvi molt important en la forma de crear i distribuir aplicacions, degut a que incorpora una sèrie d'innovacions tècniques i productives que simplifiquen molt les tasques necessàries per desenvolupar un projecte. La aparición de la plataforma. NET Framework ha supuesto un cambio muy importante en la forma de crear y distribuir aplicaciones, debido a que incorpora una serie de innovaciones técnicas y productivas que simplifican mucho...

  12. Biological Petri Nets

    CERN Document Server

    Wingender, E

    2011-01-01

    It was suggested some years ago that Petri nets might be well suited to modeling metabolic networks, overcoming some of the limitations encountered by the use of systems employing ODEs (ordinary differential equations). Much work has been done since then which confirms this and demonstrates the usefulness of this concept for systems biology. Petri net technology is not only intuitively understood by scientists trained in the life sciences, it also has a robust mathematical foundation and provides the required degree of flexibility. As a result it appears to be a very promising approach to mode

  13. Coupled Solar Wind-Magnetosphere-Ionosphere-Thermosphere System by QFT

    Science.gov (United States)

    Chen, Shao-Guang

    NM may be applied to the high-speed and the microscopic conditions. Because of the result of a test of GR with use of a hydrogen-maser frequency standard in a spacecraft launched nearly vertically upward to 10000 km (R. F. C. Vessot et.al., Phys. Rev. Lett. 45, 2081 (1980)), the isotropy of one-way velocity of light had been validated at the 1*10 (-10) level (D2.4-0030-12, H0.1-0009-12, H0.2-0008-12). Again from the Lorentz transformation (H01-0006-08) and the uncertainty principle (H05-0036-10) deduced from the metrical results of Doppler effects, SR and QM, thereby QFT and GR, all become the inferential theorems from generalized NM. Eq.(1) is as a bridge to join the modern physics and classical physics. In my paper ‘Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction’ (D31-0054-10): According to QFT the gravitation is the statistic average pressure collided by net virtual neutrinos nuν _{0} flux, the net nuν _{0} flux can press a part freedom electrons in plasma of ionosphere into the surface of celestial bodies, the static electric force of redundant positive ions prevents electrons further falling and till reach the equilibrium of stable spatial charge distribution, which is just the cause of the geomagnetic field and the geo-electric field. In the solar surface plasma add the negative charge from ionosphere electrons again rotate, thereby come into being the solar basal magnetic field. The solar surface plasma with additional electrons get the dynamic balance between the upwards force of stable positive charge distribution in the solar upside gas and the downwards force of the vacuum net nuν _{0} flux pressure (solar gravity). When the Jupiter enter into the connecting line of Sun and the center of Galaxy, the pressure (solar gravity) observed from earth will weaken because of the Jupiter stop (shield) the most net nuν _{0} flux which

  14. Reconnecting flux-rope dynamo.

    Science.gov (United States)

    Baggaley, Andrew W; Barenghi, Carlo F; Shukurov, Anvar; Subramanian, Kandaswamy

    2009-11-01

    We develop a model of the fluctuation dynamo in which the magnetic field is confined to thin flux ropes advected by a multiscale model of turbulence. Magnetic dissipation occurs only via reconnection of the flux ropes. This model can be viewed as an implementation of the asymptotic limit R_{m}-->infinity for a continuous magnetic field, where magnetic dissipation is strongly localized to small regions of strong-field gradients. We investigate the kinetic-energy release into heat mediated by the dynamo action, both in our model and by solving the induction equation with the same flow. We find that a flux-rope dynamo is an order of magnitude more efficient at converting mechanical energy into heat. The probability density of the magnetic energy release in reconnections has a power-law form with the slope -3 , consistent with the solar corona heating by nanoflares.

  15. Petri Nets-Applications

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/09/0044-0052. Author Affiliations. Y Narahari ...

  16. Safety nets or straitjackets?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    Does regulation of working hours at national and sector level impose straitjackets, or offer safety nets to employees seeking working time flexibility? This article compares legislation and collective agreements in the metal industries of Denmark, Germany and the USA. The industry has historically...

  17. Coloured Petri Nets

    CERN Document Server

    Jensen, Kurt

    2009-01-01

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. This book introduces the constructs of the CPN modelling language and presents the related analysis methods. It provides a comprehensive road map for the practical use of CPN.

  18. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  19. Game Theory .net.

    Science.gov (United States)

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  20. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism...

  1. Thermal Performance Testing of Cryogenic Multilayer Insulation with Silk Net Spacers

    Science.gov (United States)

    Johnson, W. L.; Frank, D. J.; Nast, T. C.; Fesmire, J. E.

    2015-12-01

    Early comprehensive testing of cryogenic multilayer insulation focused on the use of silk netting as a spacer material. Silk netting was used for multiple test campaigns that were designed to provide baseline thermal performance estimates for cryogenic insulation systems. As more focus was put on larger systems, the cost of silk netting became a deterrent and most aerospace insulation firms were using Dacron (or polyester) netting spacers by the early 1970s. In the midst of the switch away from silk netting there was no attempt to understand the difference between silk and polyester netting, though it was widely believed that the silk netting provided slightly better performance. Without any better reference for thermal performance data, the silk netting performance correlations continued to be used. In order to attempt to quantify the difference between the silk netting and polyester netting, a brief test program was developed. The silk netting material was obtained from Lockheed Martin and was tested on the Cryostat-100 instrument in three different configurations, 20 layers with both single and double netting and 10 layers with single netting only. The data show agreement within 15 - 30% with the historical silk netting based correlations and show a substantial performance improvement when compared to previous testing performed using polyester netting and aluminum foil/fiberglass paper multilayer insulation. Additionally, the data further reinforce a recently observed trend that the heat flux is not directly proportional to the number of layers installed on a system.

  2. Alongshore wind stress and heat flux divergence off Visakhapatnam, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Rao, B.P.; Rao, D.P.

    Annual variation of heat flux divergence (Qv) was computed for the coastal waters of Visakhapatnam. The mean values of net heat exchange (Qn) and heat flux divergence (Qv) were found to be 114 and 115 W.m/2 respectively on annual scale. The net heat...

  3. Fractal dimensions of solar activity

    Science.gov (United States)

    Watari, Shinichi

    1995-05-01

    Solar activity changes in amplitude and long-term behavior irregularly. Fractal theory is used to examine the variation of solar activity, using daily solar indices (i.e., sunspot number, 10.7 cm radio flux, the SME L alpha, Fe XIV coronal emission, and the total solar irradiance measured by the Earth Radiation Budget (ERG) on the NIMBUS-7. It can handle irregular variations quantitatively. The fractal dimension of 10.7 cm radio fluxes in cycle 21 for periods of approximately 7 days or less was 1.28, 1.3 for periods longer than approximately 272 days, and 1.86 for periods between them, for example. Fractal dimensions for other solar indices show similar tendencies. These results suggest that solar activity varies more irregularly for time scales that are longer than several days and shorter than several months. Yearly values of fractal dimensions and bending points do not change in concert with the solar cycle.

  4. Cloud effects on the solar and thermal radiation budgets of the Mediterranean basin

    Science.gov (United States)

    Pyrina, M.; Hatzianastassiou, N.; Matsoukas, C.; Fotiadi, A.; Papadimas, C. D.; Pavlakis, K. G.; Vardavas, I.

    2015-01-01

    The cloud effects on the shortwave (SW), longwave (LW) and net all-wave radiation budgets of the Mediterranean basin were computed using a detailed radiative transfer model together with satellite and reanalysis data for surface and atmospheric properties. The model radiation fluxes at TOA were validated against CERES and ERBE satellite data, while at the Earth's surface they were validated against ground-based GEBA and BSRN station measurements. The cloud radiative effects were obtained for low, middle, high-level clouds, and for total cloud cover. Overall for the basin, the effect on solar radiation is to produce radiative cooling at the top of atmosphere (TOA) and at the surface that more than balances the warming effects on terrestrial radiation. The result is a net radiative cooling at TOA and at the surface, equal to - 18.8 and - 15.9 Wm- 2, respectively. The low-level clouds are most important for the TOA budget through significant SW reflection and little LW emission to space. High clouds play an important role in net surface cooling (- 9.8 Wm- 2) through the combination of SW reflection to space and a much reduced LW warming effect at the surface. The geographical patterns of the effects are mainly characterized by a strong south to north increasing gradient. The seasonal variation of net radiative effects is dominated by solar radiation with maxima in spring and minima in winter.

  5. Mars MetNet Mission Status

    Science.gov (United States)

    Harri, Ari-Matti; Aleksashkin, Sergei; Arruego, Ignacio; Schmidt, Walter; Genzer, Maria; Vazquez, Luis; Haukka, Harri

    2015-04-01

    New kind of planetary exploration mission for Mars is under development in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested. 1. MetNet Lander The MetNet landing vehicles are using an inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used. This way the ratio of the payload mass to the overall mass is optimized. The landing impact will burrow the payload container into the Martian soil providing a more favorable thermal environment for the electronics and a suitable orientation of the telescopic boom with external sensors and the radio link antenna. It is planned to deploy several tens of MNLs on the Martian surface operating at least partly at the same time to allow meteorological network science. 2. Scientific Payload The payload of the two MNL precursor models includes the following instruments: Atmospheric instruments: 1. MetBaro Pressure device 2. MetHumi Humidity device 3. MetTemp Temperature sensors Optical devices: 1. PanCam Panoramic 2. MetSIS Solar irradiance sensor with OWLS optical wireless system for data transfer 3. DS Dust sensor The descent processes dynamic properties are monitored by a special 3-axis accelerometer combined with a 3-axis gyrometer. The data will be sent via auxiliary beacon antenna throughout the

  6. Climatology of sediment flux and composition in the subarctic Northeast Pacific Ocean with biogeochemical implications

    Science.gov (United States)

    Timothy, D. A.; Wong, C. S.; Barwell-Clarke, J. E.; Page, J. S.; White, L. A.; Macdonald, R. W.

    2013-09-01

    lithogenic component transported horizontally also reaching the 3800-m traps. A detailed description of the sampling also is provided so future experiments can benefit from the successes and failures encountered at OSP. Fluxes normalized to 2000 m are 2.7, 1.3 and 1.1 times higher than the global averages for BSi, CaCO3 and POC, respectively. The Alaska Gyre is thus a siliceous basin with unusually high calcareous fluxes. Lithogenic fluxes are minor at OSP, making this site ideal to detect dust-fall events. Fluxes of BSi and CaCO3 lag surface solar irradiance by about one month at 200 m and 1000 m, and by another ∼two weeks at 3800 m. POM is preferentially retained and recycled in the mixed layer, with maximum export occurring several months after maximum fluxes of BSi and CaCO3. Export fluxes are episodic at OSP despite perennially low chlorophyll concentrations showing little seasonality. As a result of episodically high fluxes, 40-50% of MARK7 traps with narrow sampling bottles became clogged during deployment at 3800 m. Given the common occurrence of this problem globally, traps with larger bottom orifices should become standard protocol. Sediment traps provide an excellent opportunity to test sedimentary tracers of past ocean conditions. In this regard, POC content at OSP is a poor indicator of mass or POC flux because POC is diluted by BSi and CaCO3 when mass flux is high. The annual cycle of BSi flux and a reanalysis of surface nutrient data show the spring delay in [Si(OH)4] decline, based on mixed-layer nutrient climatology, results from intense mixing in spring rather than delayed diatom growth as previously proposed. The annual cycle of POC flux, normalized to measures of net community production of organic carbon (NCPOC) in summer-fall (Emerson and Stump, 2010), implies an annual NCPOC of 3.6-5.3 mol m-2 y-1. This rate is similar to estimates of new production and of water-column OC remineralization plus deep POC flux, two equivalencies to NCPOC. It is also

  7. Global Solar Dynamo Models: Simulations and Predictions

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 29; Issue 1-2 ... Flux-transport type solar dynamos have achieved considerable success in correctly simulating many solar cycle features, and are now being used for ... We first define flux-transport dynamos and demonstrate how they work.

  8. Food Safety Nets:

    OpenAIRE

    Haggblade, Steven; Diallo, Boubacar; Staatz, John; Theriault, Veronique; Traoré, Abdramane

    2013-01-01

    Food and social safety nets have a history as long as human civilization. In hunter gatherer societies, food sharing is pervasive. Group members who prove unlucky in the short run, hunting or foraging, receive food from other households in anticipation of reciprocal consideration at a later time (Smith 1988). With the emergence of the first large sedentary civilizations in the Middle East, administrative systems developed specifically around food storage and distribution. The ancient Egyptian...

  9. Net technical assessment

    OpenAIRE

    Wegmann, David G.

    1989-01-01

    Approved for public release; distribution is unlimited. The present and near term military balance of power between the U.S. and the Soviet Union can be expressed in a variety of net assessments. One can examine the strategic nuclear balance, the conventional balance in Europe, the maritime balance, and many others. Such assessments are essential not only for policy making but for arms control purposes and future force structure planning. However, to project the future military balance, on...

  10. Estimating daytime ecosystem respiration from eddy-flux data

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Herbst, Mathias

    2011-01-01

    To understand what governs the patterns of net ecosystem exchange of CO2, an understanding of factors influencing the component fluxes, ecosystem respiration and gross primary production is needed. In the present paper, we introduce an alternative method for estimating daytime ecosystem respiration...... based on whole ecosystem fluxes from a linear regression of photosynthetic photon flux density data vs. daytime net ecosystem exchange data at forest ecosystem level. This method is based on the principles of the Kok-method applied at leaf level for estimating daytime respiration. We demonstrate...... the method with field data and provide a discussion of the limitations of the method....

  11. Dissolved organic carbon fluxes by seagrass meadows and macroalgal beds

    Directory of Open Access Journals (Sweden)

    Cristina eBarron

    2014-10-01

    Full Text Available Estimates of dissolved organic carbon (DOC release by marine macrophyte communities (seagrass meadows and macroalgal beds based on in situ benthic chambers from published and unpublished are compiled in this study. The effect of temperature and light availability on DOC release by macrophyte communities was examined. Almost 85 % of the seagrass communities and all of macroalgal communities examined acted as net sources of DOC. Net DOC fluxes in seagrass communities increase positively with water temperature. In macroalgal communities net DOC fluxes under light exceeded those under dark condition, however, this trend was weaker in seagrass communities. Shading of a mixed seagrass meadow in The Philippines led to a significant reduction on the net DOC release when shading was maintained for 6 days compared to only 2 days of shading. Net DOC fluxes increased with increasing community respiration, but were independent of primary production or net community production. The estimated global net DOC flux, and hence export, from marine macrophytes is about 0.158 ± 0.055 Pg C yr-1 or 0.175 ± 0.056 Pg C yr-1 depending on the global extent of seagrass meadows considered.

  12. Physics of magnetic flux tubes

    CERN Document Server

    Ryutova, Margarita

    2015-01-01

    This book is the first account of the physics of magnetic flux tubes from their fundamental properties to collective phenomena in an ensembles of flux tubes. The physics of magnetic flux tubes is absolutely vital for understanding fundamental physical processes in the solar atmosphere shaped and governed by magnetic fields. High-resolution and high cadence observations from recent space and  ground-based instruments taken simultaneously at different heights and temperatures not only show the ubiquity of filamentary structure formation but also allow to study how various events are interconnected by system of magnetic flux tubes. The book covers both theory and observations. Theoretical models presented in analytical and phenomenological forms are tailored for practical applications. These are welded with state-of-the-art observations from early decisive ones to the most recent data that open a new phase-space for exploring the Sun and sun-like stars. Concept of magnetic flux tubes is central to various magn...

  13. Net transport of suspended matter due to tidal straining

    Science.gov (United States)

    Jones, S. E.; Jago, C. F.; Simpson, J. H.; Rippeth, T. P.

    2003-04-01

    Net transport of suspended particulate matter (SPM) is well-known in tidal regions where there is time-velocity asymmetry due to frictional modification of the tide in shallow water. We present here observations which show a new mechanism for net flux of SPM in response to tidal straining in a region of freshwater influence (ROFI). In situ measurements of the particle size of suspended particulate matter (SPM) and turbulent energy dissipation have been made at a site in Liverpool Bay (Irish Sea) where there is significant resuspension of particles from the muddy sand substrate during spring tides. This is a ROFI where tidal straining dominates the temporal development of turbulence. On a spring tide the water column tries to stratify on the ebb and destratify on the flood, but these tendencies are masked by mixing due to tidal stirring. Nevertheless, there is a marked excess of TKE dissipation rate E on the flood, especially in the upper part of the water column. Resuspension occurs on both flood and ebb, but SPM flux is strongly asymmetric with a net shorewards component. Asymmetry is most pronounced for the larger particles which comprise most of the mass. Enhanced ? on the flood mixes large particles upwards into faster flowing water, which increases the flux. Comparable upwards mixing of large particles does not occur on the ebb where enhanced E is confined to slower bottom waters. The net flux is not seen on neap tides because, although there is more stratification due to tidal straining, there is essentially no resuspension. The net flux on springs is undoubtedly an important component of SPM transport (and any comparable particulates) in coastal regions.

  14. Characteristics of the Surface Turbulent Flux and the Components of Radiation Balance over the Grasslands in the Southeastern Tibetan Plateau

    Science.gov (United States)

    Li, H.; Xiao, Z.; Wei, J.

    2016-12-01

    Characteristics of the Surface Turbulent Flux and the Components of Radiation Balance over the Grasslands in the Southeastern Tibetan PlateauHongyi Li 1, Ziniu Xiao 2 and Junhong Wei31 China Meteorological Administration Training Centre, Beijing, China2 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China 3Theory of Atmospheric Dynamics and Climate, Institute for Atmospheric and Environmental Sciences, Goethe University of Frankfurt, Campus Riedberg, GermanyAbstract:Based on the field observation data over the grasslands in the southeastern Tibetan Plateau and the observational datasets in Nyingchi weather station for the period from May 20 to July 9, 2013, the variation characteristics of the basic meteorological elements in Nyingchi weather station, the surface turbulent fluxes and the components of radiation balance over the grasslands, as well as their relationships, are analyzed in this paper. The results show that in Nyingchi weather station, the daily variations of relative humidity and average total cloud cover are consistent with that of precipitation, but that those of daily average air temperature, daily average ground temperature, daily average wind speed and daily sunshine duration have an opposite change to that of precipitation. During the observation period, latent heat exchange is greater than sensible heat exchange, and latent heat flux is significantly higher when there is rainfall, but sensible heat flux and soil heat flux are lower. The daily variation of the total solar radiation (DR) is synchronous with that of sensible heat flux, and the daily variations of reflective solar radiation (UR), long wave radiation by earth (ULR), net radiation (Rn) and surface albedo are consistent with DR, but that of the long wave radiation by atmosphere (DLR) has an opposite change. The diurnal variations of sensible heat flux, latent

  15. Using WordNet for Building WordNets

    CERN Document Server

    Farreres, X; Farreres, Xavier; Rodriguez, Horacio; Rigau, German

    1998-01-01

    This paper summarises a set of methodologies and techniques for the fast construction of multilingual WordNets. The English WordNet is used in this approach as a backbone for Catalan and Spanish WordNets and as a lexical knowledge resource for several subtasks.

  16. Utilization of insecticide treated nets among pregnant women and ...

    African Journals Online (AJOL)

    The possibility of provision of steady light supply through the use of solar power in the homes by those who can afford it can be explored as a remedy for promoting consistent use of ITN by pregnant women and under five children in this community. Keywords: Insecticide treated nets, pregnant women, mothers, Ikot Omin, ...

  17. Global Patterns in Human Consumption of Net Primary Production

    Science.gov (United States)

    Imhoff, Marc L.; Bounoua, Lahouari; Ricketts, Taylor; Loucks, Colby; Harriss, Robert; Lawrence William T.

    2004-01-01

    The human population and its consumption profoundly affect the Earth's ecosystems. A particularly compelling measure of humanity's cumulative impact is the fraction of the planet's net primary production that we appropriate for our Net primary production-the net amount of solar energy converted to plant organic matter through photosynthesis-can be measured in units of elemental carbon and represents the primary food energy source for the world's ecosystems. Human appropriation of net primary production, apart from leaving less for other species to use, alters the composition of the atmosphere, levels of biodiversity, flows within food webs and the provision of important primary production required by humans and compare it to the total amount generated on the landscape. We then derive a spatial ba!mce sheet of net primary production supply and demand for the world. We show that human appropriation of net primary production varies spatially from almost zero to many times the local primary production. These analyses reveal the uneven footprint of human consumption and related environmental impacts, indicate the degree to which human populations depend on net primary production "imports" and suggest policy options for slowing future growth of human appropriation of net primary production.

  18. GCR flux 9-day variations with LISA Pathfinder

    Science.gov (United States)

    Grimani, C.; LISA Pathfinder Collaboration; Benella, S.; Fabi, M.; Finetti, N.; Telloni, D.

    2017-05-01

    Galactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of solar activity, the status of solar polarity and interplanetary transient magnetic structures of solar origin. A high counting rate particle detector (PD) aboard LISA Pathfinder (LPF) allows for the measurement of galactic cosmic-ray and solar energetic particle (SEP) integral fluxes at energies > 70 MeV n-1 up to 6500 counts s-1. Data are gathered with a sampling time of 15 s. A study of GCR flux depressions associated with the third harmonic of the Sun rotation period (˜ 9 days) is presented here.

  19. Calculation Tool for Determining the Net Energy Gain

    DEFF Research Database (Denmark)

    Laustsen, Jacob Birck; Svendsen, Svend

    2002-01-01

    for windows are presented. Based on these methods a program has been developed that determines the heat loss coefficient, U, and the total solar energy transmittance, g, for windows compounded of specific window components selected from a database. The program calculates the net energy gain for specific....... A proper and direct way to describe the energy performance of windows is by the net energy gain, E, which expresses the energy balance for the window. It is defined as the solar heat gain transmitted in minus the heat loss transmitted out through the window during the heating season. The net energy gain...... is dependent on both the U-values and the g-values. Beyond this it is dependent on the orientation of the windows and the climate and the actual period. This makes it difficult to choose the glazings and windows that are optimal with regard to energy performance in a given case. These facts have aroused a need...

  20. The effects of biomass burning aerosols and clouds on the CO{sub 2} flux in Amazonia

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Paulo H.F. E-mail: pauloh@if.usp.br; Artaxo, Paulo; Pires, Carlos; Lucca, Silvia De [Laboratorio de Fisica Atmosferica, Inst. de Fisica, Univ. de Sao Paulo, Rua do Matao, Travessa R, 187, Sao Paulo, SP, CEP 05508-900 (Brazil); Procopio, Aline [Dept. de Engenharia Bioquimica, Univ. Federal do Rio de Janeiro, Av. Brig. Trompowski, Rio de Janeiro, R.J., CEP: 21949-900 (Brazil); Holben, Brent; Schafer, Joel [NASA Goddard Space Flight Center, Greenbelt (United States); Cardoso, Luiz F. [UNIR Fundacao Univ. Federal de Rondonia, Campus de Ji-Parana, Ji-Parana (Brazil); Wofsy, Steven C. [Harvard Univ., Dept. of Earth and Planetary Science, 29 Oxford St., Cambridge, MA 02138 (United States); Rocha, Humberto R. [Dept. de Ciencias Atmosfericas - IAG - Univ. de Sao Paulo, Rua do Matao, 1226 - CEP 05508-900, Sao Paulo (Brazil)

    2007-07-15

    Aerosol particles associated with biomass burning emissions affect the surface radiative budget and net ecosystem exchange (NEE) over large areas in Amazonia during the dry season. We analysed CO{sub 2} fluxes as a function of aerosol loading for two forest sites in Amazonia as part of the LBA experiment. Aerosol optical thickness (AOT) measurements were made with AERONET sun photometers, and CO{sub 2} flux measurements were determined by eddy-correlation. The enhancement of the NEE varied with different aerosol loading, as well as cloud cover, solar elevation angles and other parameters. The AOT value with the strongest effect on the NEE in the FLONA-TapajOs site was 1.7, with an enhancement of the NEE of 11% compared with clear-sky conditions. In the RBJ site, the strongest effect was for AOT of 1.6 with an enhancement of 18% in the NEE. For values of AOT lager than 2.7, strong reduction on the NEE was observed due to the reduction in the total solar radiation. The enhancement in the NEE is attributed to the increase of diffuse versus direct solar radiation. Due to the fact that aerosols from biomass burning are present in most tropical areas, its effects on the global carbon budget could also be significant.

  1. Proof nets for lingusitic analysis

    NARCIS (Netherlands)

    Moot, R.C.A.

    2002-01-01

    This book investigates the possible linguistic applications of proof nets, redundancy free representations of proofs, which were introduced by Girard for linear logic. We will adapt the notion of proof net to allow the formulation of a proof net calculus which is soundand complete for the

  2. Teaching Tennis for Net Success.

    Science.gov (United States)

    Young, Bryce

    1989-01-01

    A program for teaching tennis to beginners, NET (Net Easy Teaching) is described. The program addresses three common needs shared by tennis students: active involvement in hitting the ball, clearing the net, and positive reinforcement. A sample lesson plan is included. (IAH)

  3. Net4Care Ecosystem Website

    DEFF Research Database (Denmark)

    Christensen, Henrik Bærbak; Hansen, Klaus Marius; Rasmussen, Morten

    2012-01-01

    is a tele-monitoring scenario in which Net4Care clients are deployed in a gateway in private homes. Medical devices then connect to these gateways and transmit their observations to a Net4Care server. In turn the Net4Care server creates valid clinical HL7 documents, stores them in a national XDS repository...

  4. Seasonal and latitudinal variations of surface fluxes at two Arctic terrestrial sites

    Science.gov (United States)

    Grachev, Andrey A.; Persson, P. Ola G.; Uttal, Taneil; Akish, Elena A.; Cox, Christopher J.; Morris, Sara M.; Fairall, Christopher W.; Stone, Robert S.; Lesins, Glen; Makshtas, Alexander P.; Repina, Irina A.

    2017-11-01

    This observational study compares seasonal variations of surface fluxes (turbulent, radiative, and soil heat) and other ancillary atmospheric/surface/permafrost data based on in-situ measurements made at terrestrial research observatories located near the coast of the Arctic Ocean. Hourly-averaged multiyear data sets collected at Eureka (Nunavut, Canada) and Tiksi (East Siberia, Russia) are analyzed in more detail to elucidate similarities and differences in the seasonal cycles at these two Arctic stations, which are situated at significantly different latitudes (80.0°N and 71.6°N, respectively). While significant gross similarities exist in the annual cycles of various meteorological parameters and fluxes, the differences in latitude, local topography, cloud cover, snowfall, and soil characteristics produce noticeable differences in fluxes and in the structures of the atmospheric boundary layer and upper soil temperature profiles. An important factor is that even though higher latitude sites (in this case Eureka) generally receive less annual incoming solar radiation but more total daily incoming solar radiation throughout the summer months than lower latitude sites (in this case Tiksi). This leads to a counter-intuitive state where the average active layer (or thaw line) is deeper and the topsoil temperature in midsummer are higher in Eureka which is located almost 10° north of Tiksi. The study further highlights the differences in the seasonal and latitudinal variations of the incoming shortwave and net radiation as well as the moderating cloudiness effects that lead to temporal and spatial differences in the structure of the atmospheric boundary layer and the uppermost ground layer. Specifically the warm season (Arctic summer) is shorter and mid-summer amplitude of the surface fluxes near solar noon is generally less in Eureka than in Tiksi. During the dark Polar night and cold seasons (Arctic winter) when the ground is covered with snow and air temperatures

  5. Heat flux viscosity in collisional magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C., E-mail: cliu@pppl.gov [Princeton University, Princeton, New Jersey 08544 (United States); Fox, W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Bhattacharjee, A. [Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  6. Art/Net/Work

    DEFF Research Database (Denmark)

    Andersen, Christian Ulrik; Lindstrøm, Hanne

    2006-01-01

    The seminar Art|Net|Work deals with two important changes in our culture. On one side, the network has become essential in the latest technological development. The Internet has entered a new phase, Web 2.0, including the occurrence of as ‘Wiki’s’, ‘Peer-2-Peer’ distribution, user controlled...... the praxis of the artist. We see different kinds of interventions and activism (including ‘hacktivism’) using the network as a way of questioning the invisible rules that govern public and semi-public spaces. Who ‘owns’ them? What kind of social relationships do they generate? On what principle...

  7. CO2 and heat fluxes in a recently clear-cut spruce forest in European Russia: experimental and modeling studies

    Science.gov (United States)

    Mamkin, Vadim; Kurbatova, Julia; Avilov, Vitaly; Mukhartova, Yulia; Krupenko, Alexander; Ivanov, Dmitry; Levashova, Natalia; Olchev, Alexander

    2017-04-01

    Ecosystem carbon dioxide, energy, and water fluxes were measured using eddy covariance and portable chambers in a fresh clear-cut surrounded by a mixed spruce-birch-aspen forest in the boreal zone of European Russia. Measurements were initiated in spring 2016 following timber harvest and continued for seven months until the end of October. The influence of surrounding forest on air flow and turbulent fluxes within the clear-cut were examined using a process-based two-dimensional (2D) hydrodynamic turbulent exchange model. Clear-cut was a permanent source of CO2 to the atmosphere. During the period the mean daily latent (LE) and sensible (H) heat fluxes were very similar and the Bowen ratio (β=H/LE) averaged about 1.0. During the late spring and summer months the net ecosystem exchange of CO2 (NEE) remained slightly positive following onset of vegetation growth, while β was changing in the range from 0.6 to 4.0. There was strong diurnal variability in NEE, LE and H over the measurement period that was governed by solar radiation and temperature as well as the leaf area index (LAI) of regrown vegetation. Modeled vertical CO2 and H2O fluxes along a transect that crossed the clear-cut and coincided with the dominate wind direction showed that the clear-cut strongly influenced turbulent fluxes within the atmospheric surface layer. Furthermore, modeled atmospheric dynamics suggested that the clear-cut had a large influence on turbulent fluxes in the downwind forest, but little impact on the upwind side. An aggregated approach including field measurements and process-based models can be used to estimate energy, water and carbon dioxide fluxes in non-uniform forest landscapes. This study was supported by a grant from the Russian Science Foundation (14-14-00956).

  8. Photosynthesis drives anomalies in net carbon-exchange of pine forests at different latitudes

    NARCIS (Netherlands)

    Luyssaert, S.; Janssens, I.A.; Sulkava, M.; Papale, D.; Dolman, A.J.; Reichstein, M.; Hollmén, J.; Martin, J.G.; Suni, T.; Vesala, T.; Loustau, D.; Law, B.E.; Moors, E.J.

    2007-01-01

    The growth rate of atmospheric CO2 exhibits large temporal variation that is largely determined by year-to-year fluctuations in land¿atmosphere CO2 fluxes. This land¿atmosphere CO2-flux is driven by large-scale biomass burning and variation in net ecosystem exchange (NEE). Between- and within years,

  9. Helminth.net: expansions to Nematode.net and an introduction to Trematode.net

    Science.gov (United States)

    Martin, John; Rosa, Bruce A.; Ozersky, Philip; Hallsworth-Pepin, Kymberlie; Zhang, Xu; Bhonagiri-Palsikar, Veena; Tyagi, Rahul; Wang, Qi; Choi, Young-Jun; Gao, Xin; McNulty, Samantha N.; Brindley, Paul J.; Mitreva, Makedonka

    2015-01-01

    Helminth.net (http://www.helminth.net) is the new moniker for a collection of databases: Nematode.net and Trematode.net. Within this collection we provide services and resources for parasitic roundworms (nematodes) and flatworms (trematodes), collectively known as helminths. For over a decade we have provided resources for studying nematodes via our veteran site Nematode.net (http://nematode.net). In this article, (i) we provide an update on the expansions of Nematode.net that hosts omics data from 84 species and provides advanced search tools to the broad scientific community so that data can be mined in a useful and user-friendly manner and (ii) we introduce Trematode.net, a site dedicated to the dissemination of data from flukes, flatworm parasites of the class Trematoda, phylum Platyhelminthes. Trematode.net is an independent component of Helminth.net and currently hosts data from 16 species, with information ranging from genomic, functional genomic data, enzymatic pathway utilization to microbiome changes associated with helminth infections. The databases’ interface, with a sophisticated query engine as a backbone, is intended to allow users to search for multi-factorial combinations of species’ omics properties. This report describes updates to Nematode.net since its last description in NAR, 2012, and also introduces and presents its new sibling site, Trematode.net. PMID:25392426

  10. Energy performance of windows based on the net energy gain

    DEFF Research Database (Denmark)

    Svendsen, Svend; Kragh, Jesper; Laustsen, Jacob Birck

    2005-01-01

    The paper presents a new method to set up energy performance requirements and energy classes for windows of all dimensions and configurations. The net energy gain of windows is the solar gain minus the heat loss integrated over the heating season. The net energy gain can be calculated for one...... orientation or averaged over different orientations. The averaged value may be used for energy labeling of windows of standard size. Requirements in building codes may also be based on the net energy gain instead of the thermal transmittance of the window. The size and the configuration of the window, i.......e. number of glazing units, have a very large effect on the net energy gain. Therefore the energy labeling or the requirements based on the standard size may not give valid information on the energy performance of windows of non-standard size. The paper presents a method to set up requirements and classes...

  11. Critical flux determination by flux-stepping

    DEFF Research Database (Denmark)

    Beier, Søren; Jonsson, Gunnar Eigil

    2010-01-01

    In membrane filtration related scientific literature, often step-by-step determined critical fluxes are reported. Using a dynamic microfiltration device, it is shown that critical fluxes determined from two different flux-stepping methods are dependent upon operational parameters such as step...... length, step height, and.flux start level. Filtrating 8 kg/m(3) yeast cell suspensions by a vibrating 0.45 x 10(-6) m pore size microfiltration hollow fiber module, critical fluxes from 5.6 x 10(-6) to 1.2 x 10(-5) m/s have been measured using various step lengths from 300 to 1200 seconds. Thus...

  12. How Many Solar Neutrino Experiments Are Wrong?

    OpenAIRE

    Bahcall, John N.

    1994-01-01

    Ten recently-published solar models give $\\7be$ neutrino fluxes that lie within a range of $\\pm 10$\\% of the average value, a convergence that is independent of uncertainties in the measured laboratory rate of the $\\7be(p,\\gamma)\\8b$ reaction. If nothing happens to solar neutrinos after they are created ({\\it a la} standard electroweak theory) and the operating solar neutrino experiments are correct, then the $\\7be$ solar neutrino flux must be less than 50\\% of the solar model value. At least...

  13. The equivalency between logic Petri workflow nets and workflow nets.

    Science.gov (United States)

    Wang, Jing; Yu, ShuXia; Du, YuYue

    2015-01-01

    Logic Petri nets (LPNs) can describe and analyze batch processing functions and passing value indeterminacy in cooperative systems. Logic Petri workflow nets (LPWNs) are proposed based on LPNs in this paper. Process mining is regarded as an important bridge between modeling and analysis of data mining and business process. Workflow nets (WF-nets) are the extension to Petri nets (PNs), and have successfully been used to process mining. Some shortcomings cannot be avoided in process mining, such as duplicate tasks, invisible tasks, and the noise of logs. The online shop in electronic commerce in this paper is modeled to prove the equivalence between LPWNs and WF-nets, and advantages of LPWNs are presented.

  14. Magnetic Fields in the Solar Convection Zone

    Directory of Open Access Journals (Sweden)

    Fan Yuhong

    2004-07-01

    Full Text Available Recent studies of the dynamic evolution of magnetic flux tubes in the solar convection zone are reviewed with focus on emerging flux tubes responsible for the formation of solar active regions. The current prevailing picture is that active regions on the solar surface originate from strong toroidal magnetic fields generated by the solar dynamo mechanism at the thin tachocline layer at the base of the solar convection zone. Thus the magnetic fields need to traverse the entire convection zone before they reach the photosphere to form the observed solar active regions. This review discusses results with regard to the following major topics: 1. the equilibrium properties of the toroidal magnetic fields stored in the stable overshoot region at the base of the convection zone, 2. the buoyancy instability associated with the toroidal magnetic fields and the formation of buoyant magnetic flux tubes, 3. the rise of emerging flux loops through the solar convective envelope as modeled by the thin flux tube calculations which infer that the field strength of the toroidal magnetic fields at the base of the solar convection zone is significantly higher than the value in equipartition with convection, 4. the minimum twist needed for maintaining cohesion of the rising flux tubes, 5. the rise of highly twisted kink unstable flux tubes as a possible origin of d -sunspots, 6. the evolution of buoyant magnetic flux tubes in 3D stratified convection, 7. turbulent pumping of magnetic flux by penetrative compressible convection, 8. an alternative mechanism for intensifying toroidal magnetic fields to significantly super-equipartition field strengths by conversion of the potential energy associated with the superadiabatic stratification of the solar convection zone, and finally 9. a brief overview of our current understanding of flux emergence at the surface and post-emergence evolution of the subsurface magnetic fields.

  15. Solar Indices - Solar Ultraviolet

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  16. Solar Indices - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  17. Solar Indices - Solar Corona

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  18. Solar Indices - Solar Irradiance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  19. Relationships of a growing magnetic flux region to flares

    NARCIS (Netherlands)

    Schadee, A.; Martin, S.F.; Bentley, R.D.; Antalova, A.; Kucera, A.; Dezs, L.; Gesztelyi, L.; Harvey, K.L.; Jones, H.; Livi, S.H.B.; Wang, J.

    1984-01-01

    Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic

  20. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    tribpo

    Dynamical Processes in Flux Tubes and their Role in Chromospheric. Heating. S. S. Hasan, Indian Institute of Astrophysics, Bangalore 560034, India, e-mail: hasan@iiap.ernet.in. Abstract. We model the dynamical interaction between magnetic flux tubes and granules in the solar photosphere which leads to the excitation of.

  1. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    We model the dynamical interaction between magnetic flux tubes and granules in the solar photosphere which leads to the excitation of transverse (kink) and longitudinal (sausage) tube waves. The investigation is motivated by the interpretation of network oscillations in terms of flux tube waves. The calculations show that ...

  2. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    studies that illustrate the practical use of CPN modelling and validation for design, specification, simulation, verification and implementation in various application domains. Their presentation primarily aims at readers interested in the practical use of CPN. Thus all concepts and constructs are first......Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism...... and the immense number of possible execution sequences. In this textbook, Jensen and Kristensen introduce the constructs of the CPN modelling language and present the related analysis methods in detail. They also provide a comprehensive road map for the practical use of CPN by showcasing selected industrial case...

  3. Cascade sensitivity studies for KM3NeT

    Directory of Open Access Journals (Sweden)

    Fusco Luigi Antonio

    2016-01-01

    Full Text Available KM3NeT is a future research infrastructure in the deep seas of the Mediterranean housing a large scale neutrino telescope. The first phase of construction of the telescope has started. Next step is an intermediate phase realising a detector volume of about one-third of the final detector volume. We report on calculations of the sensitivity of the KM3NeT detector to showering neutrino events, the strategy to optimise the detector to a cosmic neutrino flux analogous to the one reported by the IceCube Collaboration and the results of this strategy applied to the intermediate phase detector.

  4. Glycol/water evacuated-tube solar collector

    Science.gov (United States)

    1980-01-01

    Report describes performance of 8 tube and 10 tube commercially produced solar collectors. Tests include thermal efficiency, time constant for temperature drop after solar flux is cut, change in efficiency with Sun angle, and temperature rise if circulation is stopped.

  5. Solar electricity in the Swedish distribution net. How to handle overproduction frm PV-plants in the future; Solel i det svenska elnaetet. Hur man handskas med oeverproduktion fraan PV-anlaeggningar i framtiden

    Energy Technology Data Exchange (ETDEWEB)

    Roennelid, Mats; Estevez, Nicolas Sebastian

    2007-12-28

    Due to the continued growth of installed area of Photovoltaic (PV) panels, Sweden will face a problem with electricity overproduction when PV panel production accounts for about 9% of total yearly electricity demand. Although this scenario might be over a decade away from happening it is important to look ahead now and make sure that our current practices and standards do not lead us into trouble in the future. This thesis explores the issue of Photovoltaic electricity overproduction in Sweden. The methodology of this work includes analyzing hourly weather data measured in five Swedish cities over several years and hourly electricity demand data of whole Sweden. A solar simulation program was written that would use the hourly weather data and calculate hourly insolation on tilted surfaces. The solar simulator output was used to calculate the area of PV when overproduction becomes a problem in Sweden and to explore the effect of surface tilt and orientation on yearly usable electricity production when the PV area grows beyond that point. This area is referred to as A{sub 0} in this text, and the best guess for Sweden was about 128 million square meters. Some scenarios with an installed PV area equal to different multiples of A{sub 0} were studied. Options of varying tilt and orientation angle could be evaluated to see which one would result in the highest yearly output. For example when the installed area equals 2 x A{sub 0} the highest output from the PV panels result from pointing the panels in the same way as with no overproduction. Only a 6% overproduction loss is suffered from doubling the Max Area of Zero Over-production and PV would be able to cover about 17% of the yearly Swedish electric demand. Beyond doubling of A{sub 0} the angles become less important. This is because as the overproduction becomes higher for the optimal angles the non-optimum angles which are able to avoid overproduction will still have comparable yield. However the best yields are

  6. Jamaica National Net-Billing Pilot Program Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Doris, Elizabeth [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stout, Sherry [National Renewable Energy Lab. (NREL), Golden, CO (United States); Peterson, Kimberly [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-12-18

    This technical report discusses the effectiveness of the Jamaica Public Service Company Limited Net-Billing Pilot Program. The National Renewable Energy Laboratory (NREL) collected and analyzed data from a wide range of stakeholders, conducted in-country research, and compared program elements to common interconnection practices to form programmatic recommendations for the Jamaica context. NREL finds that the net-billing pilot program has successfully contributed to the support of the emerging solar market in Jamaica with the interconnection of 80 systems under the program for a total of 1.38 megawatts (MW) at the time of original analysis.

  7. Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

    Directory of Open Access Journals (Sweden)

    M. V. Thomas

    2011-06-01

    Full Text Available We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE data were partitioned into gross primary productivity (GPP and ecosystem respiration (Re and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1 Mg C ha−1 yr−1 and Re to be 19.8 Mg C ha−1 yr−1; net ecosystem productivity (NEP was 1.2 Mg C ha−1 yr−1. These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 ± 6.8 Mg C ha−1 yr−1, Re = 24.8 ± 6.8 Mg C ha−1 yr−1, biomass increment = ~1.7 Mg C ha−1 yr−1. Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO2 fluxes (R2 = 0.53 for the summer months for a linear regression, variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods

  8. Spectral variation of the solar radiation during an eclipse

    OpenAIRE

    Peter Koepke; Joachim Reuder; Jan Schween

    2001-01-01

    The time dependent variation of the spectral extraterrestrial solar flux is modelled for the conditions during a total eclipse. These data are used to calculate irradiance and actinic flux at the Earths surface for atmospheric conditions of August 11, 1999 at Weihenstephan. These results are compared with measurements. It is shown, that the spectral composition of solar radiation varies during the eclipse, since solar limb darkening has a spectral dependence. The solar radiation differs from ...

  9. Some solar radiation ratios and their interpretations with regards to ...

    African Journals Online (AJOL)

    Ratios of some radiation fluxes such as global (total) solar radiation, H, direct solar radiation, Hb, diffuse solar radiation, Hd, and extraterrestrial radiation, Ho were proposed to define radiation coefficients related to radiation transfer in the atmosphere and solar radiation measurement on the ground surface. The irradiative ...

  10. Solar Indices Forecasting Tool

    Science.gov (United States)

    Henney, Carl John; Shurkin, Kathleen; Arge, Charles; Hill, Frank

    2016-05-01

    Progress to forecast key space weather parameters using SIFT (Solar Indices Forecasting Tool) with the ADAPT (Air Force Data Assimilative Photospheric flux Transport) model is highlighted in this presentation. Using a magnetic flux transport model, ADAPT, we estimate the solar near-side field distribution that is used as input into empirical models for predicting F10.7(solar 10.7 cm, 2.8 GHz, radio flux), the Mg II core-to-wing ratio, and selected bands of solar far ultraviolet (FUV) and extreme ultraviolet (EUV) irradiance. Input to the ADAPT model includes the inferred photospheric magnetic field from the NISP ground-based instruments, GONG & VSM. Besides a status update regarding ADAPT and SIFT models, we will summarize the findings that: 1) the sum of the absolute value of strong magnetic fields, associated with sunspots, is shown to correlate well with the observed daily F10.7 variability (Henney et al. 2012); and 2) the sum of the absolute value of weak magnetic fields, associated with plage regions, is shown to correlate well with EUV and FUV irradiance variability (Henney et al. 2015). This work utilizes data produced collaboratively between Air Force Research Laboratory (AFRL) and the National Solar Observatory (NSO). The ADAPT model development is supported by AFRL. The input data utilized by ADAPT is obtained by NISP (NSO Integrated Synoptic Program). NSO is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation (NSF). The 10.7 cm solar radio flux data service, utilized by the ADAPT/SIFT F10.7 forecasting model, is operated by the National Research Council of Canada and National Resources Canada, with the support of the Canadian Space Agency.

  11. The heating and acceleration actions of the solar plasma wave by QFT

    Science.gov (United States)

    Chen, Shao-Guang

    measuring value of one-way velocity of light (H05-0006-08) to replace the infinity value of light speed measured by Galileo in 1607, thereby the mass m in NM will become variable m. Or else, the energy of electron in accelerator should not larger than 0.51Mev which conflict with the experimental fact. According to the variable mass and the definition of force we again get Eq.(1) from NM without hypothesis, i.e., NM is generalized in which Galileo coordinates transformation and the action at a distance will be of no effect. Eq.(1) has more reliable experimental base and generalized NM may be applied to the high-speed and the microscopic conditions. Because of the result of a test of GR with use of a hydrogen-maser frequency standard in a spacecraft launched nearly vertically upward to 10000 km (R. F. C. Vessot et.al., Phys. Rev. Lett. 45, 2081 (1980)), the isotropy of one-way velocity of light had been validated at the 1*10 (-10) level (D2.4-0030-12, H0.1-0009-12, H0.2-0008-12). Again from the Lorentz transformation (H01-0006-08) and the uncertainty principle (H05-0036-10) deduced from the metrical results of Doppler effects, SR and QM, thereby QFT and GR, all become the inferential theorems from generalized NM. Eq.(1) is as a bridge to join the modern physics and classical physics. In my paper ‘Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction’ (D31-0054-10): According to QFT the gravitation is the statistic average pressure collided by net virtual neutrinos nuν _{0} flux, the net nuν _{0} flux can press a part freedom electrons in plasma of ionosphere into the surface of celestial bodies, the static electric force of redundant positive ions prevents electrons further falling and till reach the equilibrium of stable spatial charge distribution, which is just the cause of the geomagnetic field and the geo-electric field. In the solar surface plasma add

  12. The Analytical Objective Hysteresis Model (AnOHM v1.0: methodology to determine bulk storage heat flux coefficients

    Directory of Open Access Journals (Sweden)

    T. Sun

    2017-07-01

    Full Text Available The net storage heat flux (ΔQS is important in the urban surface energy balance (SEB but its determination remains a significant challenge. The hysteresis pattern of the diurnal relation between the ΔQS and net all-wave radiation (Q∗ has been captured in the Objective Hysteresis Model (OHM parameterization of ΔQS. Although successfully used in urban areas, the limited availability of coefficients for OHM hampers its application. To facilitate use, and enhance physical interpretations of the OHM coefficients, an analytical solution of the one-dimensional advection–diffusion equation of coupled heat and liquid water transport in conjunction with the SEB is conducted, allowing development of AnOHM (Analytical Objective Hysteresis Model. A sensitivity test of AnOHM to surface properties and hydrometeorological forcing is presented using a stochastic approach (subset simulation. The sensitivity test suggests that the albedo, Bowen ratio and bulk transfer coefficient, solar radiation and wind speed are most critical. AnOHM, driven by local meteorological conditions at five sites with different land use, is shown to simulate the ΔQS flux well (RMSE values of ∼ 30 W m−2. The intra-annual dynamics of OHM coefficients are explored. AnOHM offers significant potential to enhance modelling of the surface energy balance over a wider range of conditions and land covers.

  13. The Solar Cycle

    Directory of Open Access Journals (Sweden)

    David H. Hathaway

    2015-09-01

    Full Text Available The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev–Ohl (even-odd Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

  14. Solar History An Introduction

    CERN Document Server

    Vita-Finzi, Claudio

    2013-01-01

    Beyond the four centuries of sunspot observation and the five decades during which artificial satellites have monitored the Sun – that is to say for 99.99999% of the Sun’s existence – our knowledge of solar history depends largely on analogy with kindred main sequence stars, on the outcome of various kinds of modelling, and on indirect measures of solar activity. They include the analysis of lunar rocks and meteorites for evidence of solar flares and other components of the solar cosmic-ray (SCR) flux, and the measurement of cosmogenic isotopes in wood, stratified ice and marine sediments to evaluate changes in the galactic cosmic-ray (GCR) flux and thus infer changes in the sheltering magnetic fields of the solar wind. In addition, shifts in the global atmospheric circulation which appear to result from cyclic fluctuations in solar irradiance have left their mark in river sediments and in the isotopic composition of cave deposits. In this volume the results these sources have already produced have bee...

  15. Flux-P: Automating Metabolic Flux Analysis

    Directory of Open Access Journals (Sweden)

    Birgitta E. Ebert

    2012-11-01

    Full Text Available Quantitative knowledge of intracellular fluxes in metabolic networks is invaluable for inferring metabolic system behavior and the design principles of biological systems. However, intracellular reaction rates can not often be calculated directly but have to be estimated; for instance, via 13C-based metabolic flux analysis, a model-based interpretation of stable carbon isotope patterns in intermediates of metabolism. Existing software such as FiatFlux, OpenFLUX or 13CFLUX supports experts in this complex analysis, but requires several steps that have to be carried out manually, hence restricting the use of this software for data interpretation to a rather small number of experiments. In this paper, we present Flux-P as an approach to automate and standardize 13C-based metabolic flux analysis, using the Bio-jETI workflow framework. Exemplarily based on the FiatFlux software, it demonstrates how services can be created that carry out the different analysis steps autonomously and how these can subsequently be assembled into software workflows that perform automated, high-throughput intracellular flux analysis of high quality and reproducibility. Besides significant acceleration and standardization of the data analysis, the agile workflow-based realization supports flexible changes of the analysis workflows on the user level, making it easy to perform custom analyses.

  16. Heat in the Barents Sea: transport, storage, and surface fluxes

    Directory of Open Access Journals (Sweden)

    L. H. Smedsrud

    2010-02-01

    Full Text Available A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic seasonal cycle can be reproduced fairly well.

    Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production.

    The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating.

    During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.

  17. Solar thermal financing guidebook

    Energy Technology Data Exchange (ETDEWEB)

    Williams, T.A.; Cole, R.J.; Brown, D.R.; Dirks, J.A.; Edelhertz, H.; Holmlund, I.; Malhotra, S.; Smith, S.A.; Sommers, P.; Willke, T.L.

    1983-05-01

    This guidebook contains information on alternative financing methods that could be used to develop solar thermal systems. The financing arrangements discussed include several lease alternatives, joint venture financing, R and D partnerships, industrial revenue bonds, and ordinary sales. In many situations, alternative financing arrangements can significantly enhance the economic attractiveness of solar thermal investments by providing a means to efficiently allocate elements of risk, return on investment, required capital investment, and tax benefits. A net present value approach is an appropriate method that can be used to investigate the economic attractiveness of alternative financing methods. Although other methods are applicable, the net present value approach has advantages of accounting for the time value of money, yielding a single valued solution to the financial analysis, focusing attention on the opportunity cost of capital, and being a commonly understood concept that is relatively simple to apply. A personal computer model for quickly assessing the present value of investments in solar thermal plants with alternative financing methods is presented in this guidebook. General types of financing arrangements that may be desirable for an individual can be chosen based on an assessment of his goals in investing in solar thermal systems and knowledge of the individual's tax situation. Once general financing arrangements have been selected, a screening analysis can quickly determine if the solar investment is worthy of detailed study.

  18. Solar cycle dependence of scaling in solar wind fluctuations

    Directory of Open Access Journals (Sweden)

    S. C. Chapman

    2008-06-01

    Full Text Available In this review we collate recent results for the statistical scaling properties of fluctuations in the solar wind with a view to synthesizing two descriptions: that of evolving MHD turbulence and that of a scaling signature of coronal origin that passively propagates with the solar wind. The scenario that emerges is that of coexistent signatures which map onto the well known "two component" picture of solar wind magnetic fluctuations. This highlights the need to consider quantities which track Alfvénic fluctuations, and energy and momentum flux densities to obtain a complete description of solar wind fluctuations.

  19. Solar cycle dependence of scaling in solar wind fluctuations

    Science.gov (United States)

    Chapman, S. C.; Hnat, B.; Kiyani, K.

    2008-06-01

    In this review we collate recent results for the statistical scaling properties of fluctuations in the solar wind with a view to synthesizing two descriptions: that of evolving MHD turbulence and that of a scaling signature of coronal origin that passively propagates with the solar wind. The scenario that emerges is that of coexistent signatures which map onto the well known "two component" picture of solar wind magnetic fluctuations. This highlights the need to consider quantities which track Alfvénic fluctuations, and energy and momentum flux densities to obtain a complete description of solar wind fluctuations.

  20. Benthic fluxes in San Francisco Bay

    Science.gov (United States)

    Hammond, Douglas E.; Fuller, C.; Harmon, D.; Hartman, Blayne; Korosec, M.; Miller, L.G.; Rea, R.; Warren, S.; Berelson, W.; Hager, S.W.

    1985-01-01

    Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal

  1. Linear Logic on Petri Nets

    DEFF Research Database (Denmark)

    Engberg, Uffe Henrik; Winskel, Glynn

    This article shows how individual Petri nets form models of Girard's intuitionistic linear logic. It explores questions of expressiveness and completeness of linear logic with respect to this interpretation. An aim is to use Petri nets to give an understanding of linear logic and give some apprai...

  2. Reference Guide Microsoft.NET

    NARCIS (Netherlands)

    Zee M van der; Verspaij GJ; Rosbergen S; IMP; NMD

    2003-01-01

    Developers, administrators and managers can get more understanding of the .NET technology with this report. They can also make better choices how to use this technology. The report describes the results and conclusions of a study of the usability for the RIVM of this new generation .NET development

  3. Net neutrality and audiovisual services

    NARCIS (Netherlands)

    van Eijk, N.; Nikoltchev, S.

    2011-01-01

    Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication

  4. Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

    Directory of Open Access Journals (Sweden)

    W. R. Coley

    2014-02-01

    Full Text Available The Ion Velocity Meter (IVM, a part of the Coupled Ion Neutral Dynamic Investigation (CINDI instrument package on the Communication/Navigation Outage Forecast System (C/NOFS spacecraft, has made over 5 yr of in situ measurements of plasma temperatures, composition, densities, and velocities in the 400–850 km altitude range of the equatorial ionosphere. These measured ion velocities are then transformed into a coordinate system with components parallel and perpendicular to the geomagnetic field allowing us to examine the zonal (horizontal and perpendicular to the geomagnetic field component of plasma motion over the 2009–2012 interval. The general pattern of local time variation of the equatorial zonal ion velocity is well established as westward during the day and eastward during the night, with the larger nighttime velocities leading to a net ionospheric superrotation. Since the C/NOFS launch in April 2008, F10.7 cm radio fluxes have gradually increased from around 70 sfu to levels in the 130–150 sfu range. The comprehensive coverage of C/NOFS over the low-latitude ionosphere allows us to examine variations of the topside zonal ion velocity over a wide level of solar activity as well as the dependence of the zonal velocity on apex altitude (magnetic latitude, longitude, and solar local time. It was found that the zonal ion drifts show longitude dependence with the largest net eastward values in the American sector. The pre-midnight zonal drifts show definite solar activity (F10.7 dependence. The daytime drifts have a lower dependence on F10.7. The apex altitude (magnetic latitude variations indicate a more westerly flow at higher altitudes. There is often a net topside subrotation at low F10.7 levels, perhaps indicative of a suppressed F region dynamo due to low field line-integrated conductivity and a low F region altitude at solar minimum.

  5. A Small Universal Petri Net

    Directory of Open Access Journals (Sweden)

    Dmitry A. Zaitsev

    2013-09-01

    Full Text Available A universal deterministic inhibitor Petri net with 14 places, 29 transitions and 138 arcs was constructed via simulation of Neary and Woods' weakly universal Turing machine with 2 states and 4 symbols; the total time complexity is exponential in the running time of their weak machine. To simulate the blank words of the weakly universal Turing machine, a couple of dedicated transitions insert their codes when reaching edges of the working zone. To complete a chain of a given Petri net encoding to be executed by the universal Petri net, a translation of a bi-tag system into a Turing machine was constructed. The constructed Petri net is universal in the standard sense; a weaker form of universality for Petri nets was not introduced in this work.

  6. Solar building

    OpenAIRE

    Zhang, Luxin

    2014-01-01

    In my thesis I describe the utilization of solar energy and solar energy with building integration. In introduction it is also mentioned how the solar building works, trying to make more people understand and accept the solar building. The thesis introduces different types of solar heat collectors. I compared the difference two operation modes of solar water heating system and created examples of solar water system selection. I also introduced other solar building applications. It is conv...

  7. Flux Analysis in Process Models via Causality

    Directory of Open Access Journals (Sweden)

    Ozan Kahramanoğulları

    2010-02-01

    Full Text Available We present an approach for flux analysis in process algebra models of biological systems. We perceive flux as the flow of resources in stochastic simulations. We resort to an established correspondence between event structures, a broadly recognised model of concurrency, and state transitions of process models, seen as Petri nets. We show that we can this way extract the causal resource dependencies in simulations between individual state transitions as partial orders of events. We propose transformations on the partial orders that provide means for further analysis, and introduce a software tool, which implements these ideas. By means of an example of a published model of the Rho GTP-binding proteins, we argue that this approach can provide the substitute for flux analysis techniques on ordinary differential equation models within the stochastic setting of process algebras.

  8. Untwisting Jets Related to Magnetic Flux Cancellation

    Science.gov (United States)

    Liu, Jiajia; Erdélyi, Robert; Wang, Yuming; Liu, Rui

    2018-01-01

    The rotational motion of solar jets is believed to be a signature of the untwisting process resulting from magnetic reconnection, which takes place between twisted closed magnetic loops (i.e., magnetic flux ropes) and open magnetic field lines. The identification of the pre-existing flux rope, and the relationship between the twist contained in the rope and the number of turns the jet experiences, are then vital in understanding the jet-triggering mechanism. In this paper, we will perform a detailed analysis of imaging, spectral, and magnetic field observations of four homologous jets, among which the fourth one releases a twist angle of 2.6π. Nonlinear force-free field extrapolation of the photospheric vector magnetic field before the jet eruption presents a magnetic configuration with a null point between twisted and open fields—a configuration highly in favor of the eruption of solar jets. The fact that the jet rotates in the opposite sense of handness to the twist contained in the pre-eruption photospheric magnetic field confirms the unwinding of the twist by the jet’s rotational motion. The temporal relationship between jets’ occurrence and the total negative flux at their source region, together with the enhanced magnetic submergence term of the photospheric Poynting flux, shows that these jets are highly associated with local magnetic flux cancellation.

  9. Solar energy and the aeronautics industry. Thesis

    Science.gov (United States)

    Benedek, L.

    1985-01-01

    An introduction to the physical aspects of solar energy, incidental energy and variations in solar flux is presented, along with an explanation of the physical principles of obtaining solar energy. The history of the application of solar energy to aeronautics, including the Gossamer Penguin and the Solar Challenger is given. Finally, an analysis of the possibilities of using a reaction motor with hybrid propulsion combining solar energy with traditional fuels as well as calculations of the proposed cycle and its mode of operation are given.

  10. Gap filling strategies for long term energy flux data sets

    DEFF Research Database (Denmark)

    Falge, E.; Baldocchi, D.; Olson, R.

    2001-01-01

    At present a network of over 100 field sites are measuring carbon dioxide, water vapor and sensible heat fluxes between the biosphere and atmosphere, on a nearly continuous basis. Gaps in the long term measurements of evaporation and sensible heat flux must be filled before these data can be used...... for hydrological and meteorological applications. We adapted methods of gap filling for NEE (net ecosystem exchange of carbon) to energy fluxes and applied them to data sets available from the EUROFLUX and AmeriFlux eddy covariance databases. The average data coverage for the sites selected was 69% and 75......% for latent heat (lambdaE) and sensible heat (H). The methods were based on mean diurnal variations (half-hourly binned means of fluxes based on previous and subsequent days, MDV) and look-up tables for fluxes during assorted meteorological conditions (LookUp), and the impact of different gap filling methods...

  11. Numerical Simulations of a Flux Rope Ejection P. Pagano1,∗, D. H. ...

    Indian Academy of Sciences (India)

    Abstract. Coronal mass ejections (CMEs) are the most violent phenom- ena observed on the Sun. One of the most successful models to explain. CMEs is the flux rope ejection model, where a magnetic flux rope is expelled from the solar corona after a long phase along which the flux rope stays in equilibrium while magnetic ...

  12. Load Matching and Grid Interaction of Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Voss, Karsten; Sartori, Igor; Napolitano, Assunta

    2010-01-01

    of seasonal energy storage on-site. Even though the wording “Net Zero Energy Building” focuses on the annual energy balance, large differences may occur between solution sets in the amount of grid interaction needed to reach the goal. The paper reports on the analysis of example buildings concerning the load...... matching and grid interaction. Indices to describe both issues are proposed and foreseen as part of a harmonized definition framework. The work is part of subtask A of the IEA SHCP Task40/ECBCS Annex 52: “Towards Net Zero Energy Solar Buildings”.......“Net Zero Energy Building” has become a prominent wording to describe the synergy of energy efficient building and renewable energy utilization to reach a balanced energy budget over a yearly cycle. Taking into account the energy exchange with a grid infrastructure overcomes the limitations...

  13. Design and implementation of a 38 kW dish-Stirling concentrated solar power system

    Science.gov (United States)

    Yan, J.; Peng, Y. D.; Cheng, Z. R.; Liu, F. M.; Tang, X. H.

    2017-11-01

    Dish-Stirling concentrated solar power system (DS-CSP) is an important pathway for converting solar energy into electricity at high efficiency. In this study, a rated power 38 kW DS-CSP system was developed (installed in Xiangtan Electric Manufacturing Group). The heat engine adopted the alpha-type four cylinders double-acting Stirling engine (Stirling Biopower Flexgen S260). The absorber flux distribution simulation was conducted using ray tracing method and then the 204 m2 parabolic dish concentrator system (diameter is 17.70 m and focal length is 9.49 m) with single concentrator plus single pillar supporting has been designed and built. A water-cooled disc target and an absorber imitation device were adopted to test the tracking performance of the dish concentrator system, homogeneity of the focal spot and flux distribution of the absorber. Finally, the S260 Stirling engine was installed on the focal position of the dish concentrator and then the net output power date of the 38 kW DS-CSP system was tested. The absorber overheating problem on the DS-CSP system performance was discussed when the DS-CSP system was installed in different locations. The testing result shows that this system achieved the net output power of 38 kW and solar-to-electricity efficiency (SEE) of 25.3% with the direct normal irradiation (DNI) at 750 W/m2. The net output power can further increase to 40.5 kW with the SEE of 26.6% when the DNI reaches up to the maximum of 761 W/m2. The net output power of the 38 kW DS-CSP system has a linear function relationship with the DNI. The fitting function is Net power output=0.1003×DNI-36.129, where DNI is at the range of 460∼761 W/m2. This function could be used to predict the amount of the 38 kW DS-CSP system annual generation power.

  14. High-level Petri Nets

    DEFF Research Database (Denmark)

    High-level Petri nets are now widely used in both theoretical analysis and practical modelling of concurrent systems. The main reason for the success of this class of net models is that they make it possible to obtain much more succinct and manageable descriptions than can be obtained by means...... of low-level Petri nets - while, on the other hand, they still offer a wide range of analysis methods and tools. The step from low-level nets to high-level nets can be compared to the step from assembly languages to modern programming languages with an elaborated type concept. In low-level nets...... there is only one kind of token and this means that the state of a place is described by an integer (and in many cases even by a boolean). In high-level nets each token can carry a complex information/data - which, e.g., may describe the entire state of a process or a data base. Today most practical...

  15. Applications of nonimaging optics for very high solar concentrations

    Energy Technology Data Exchange (ETDEWEB)

    O`Gallagher, J.; Winston, R.

    1997-12-31

    Using the principles and techniques of nonimaging optics, solar concentrations that approach the theoretical maximum can be achieved. This has applications in solar energy collection wherever concentration is desired. In this paper, we survey recent progress in attaining and using high and ultrahigh solar fluxes. We review a number of potential applications for highly concentrated solar energy and the current status of the associated technology. By making possible new and unique applications for intense solar flux, these techniques have opened a whole new frontier for research and development of potentially economic uses of solar energy.

  16. NACP MCI: CO2 Flux from Inversion Modeling, Upper Midwest Region, USA, 2007

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides estimates of Net Ecosystem Exchange (NEE) flux for the U.S. Upper Midwest at 0.5-degree resolution for the year 2007. Estimates were...

  17. NACP MCI: CO2 Flux from Inversion Modeling, Upper Midwest Region, USA, 2007

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides estimates of Net Ecosystem Exchange (NEE) flux for the U.S. Upper Midwest at 0.5-degree resolution for the year 2007. Estimates were produced...

  18. LBA-ECO TG-08 Soil Gas Flux after Forest and Pasture Fertilization, Rondonia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides nitric oxide (NO), nitrous oxide (N2O), carbon dioxide (CO2) flux measurements, nitrogen (N) and phosphorus (P) pools, net N mineralization...

  19. CMS: Carbon Fluxes from Global Agricultural Production and Consumption, 2005-2011

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides global estimates of carbon fluxes associate with annual crop net primary production (NPP) and harvested biomass, annual uptake and release by...

  20. NACP VPRM NEE Parameters Optimized to North American Flux Tower Sites, 2000-2006

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides Vegetation Photosynthesis Respiration Model (VPRM) net ecosystem exchange (NEE) parameter values optimized to 65 flux tower sites across North...

  1. LBA-ECO TG-08 Soil Gas Flux after Forest and Pasture Fertilization, Rondonia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides nitric oxide (NO), nitrous oxide (N2O), carbon dioxide (CO2) flux measurements, nitrogen (N) and phosphorus (P) pools, net N...

  2. Pro asynchronous programming with .NET

    CERN Document Server

    Blewett, Richard; Ltd, Rock Solid Knowledge

    2014-01-01

    Pro Asynchronous Programming with .NET teaches the essential skill of asynchronous programming in .NET. It answers critical questions in .NET application development, such as: how do I keep my program responding at all times to keep my users happy how do I make the most of the available hardware how can I improve performanceIn the modern world, users expect more and more from their applications and devices, and multi-core hardware has the potential to provide it. But it takes carefully crafted code to turn that potential into responsive, scalable applications.With Pro Asynchronous Programming

  3. Conformal Nets II: Conformal Blocks

    Science.gov (United States)

    Bartels, Arthur; Douglas, Christopher L.; Henriques, André

    2017-08-01

    Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.

  4. Stoichiometry and Life-History Interact to Determine the Magnitude of Cross-Ecosystem Element and Biomass Fluxes.

    Science.gov (United States)

    Luhring, Thomas M; DeLong, John P; Semlitsch, Raymond D

    2017-01-01

    Ecosystems are linked through the transfer of materials and energy. Studies examining material fluxes across habitat boundaries frequently quantify unidirectional flows of nutrients and energy. However, material fluxes can be multidirectional, and we lack a conceptual framework to describe how their quantity and stoichiometry influence the net transfer of individual elements between ecosystems. Here we develop a zero net transfer isocline (ZNTI) framework that integrates the relative mass and stoichiometry of fluxes into and out of an ecosystem. We then use case studies with amphibians and salmon to elucidate how life history, ontogenetic shifts in stoichiometry, and trophic interactions shape relative fluxes of nutrients between aquatic and terrestrial ecosystems. Because they increase in both size and Ca content from ova to metamorphs, amphibian life histories strongly bias them toward net Ca export into the terrestrial environment. Because amphibian biomass, C, P, and Ca ZNTIs do not overlap, there is no value of survivorship where the net flux of biomass, C, P, and Ca are simultaneously balanced between terrestrial and aquatic habitats. The degree of iteroparity and semelparity in salmon strongly affects both the magnitude of net biomass and P flux between riverine and marine environments. While the net direction of biomass flux generally remains strongly biased toward import into the riverine system, net P flux can reach net export into the marine environment because of increasing adult breeding survival leading to reduced mass and %P of what they deposit in rivers (e.g., ova vs. whole carcasses). These examples highlight how ontogenetic shifts in body size and stoichiometry result in asymmetric fluxes of elements and biomass that can lead to simultaneous net imports and exports of different elements within the same system. Furthermore, they demonstrate how changes in life-history characteristics and stage-specific survivorship can lead to changes in net

  5. Magnetic Fields in the Solar Convection Zone

    Directory of Open Access Journals (Sweden)

    Yuhong Fan

    2009-12-01

    Full Text Available Active regions on the solar surface are generally thought to originate from a strong toroidal magnetic field generated by a deep seated solar dynamo mechanism operating at the base of the solar convection zone. Thus the magnetic fields need to traverse the entire convection zone before they reach the photosphere to form the observed solar active regions. Understanding this process of active region flux emergence is therefore a crucial component for the study of the solar cycle dynamo. This article reviews studies with regard to the formation and rise of active region scale magnetic flux tubes in the solar convection zone and their emergence into the solar atmosphere as active regions.

  6. Effects of different drivers on ion fluxes at Mars. MARS EXPRESS and MAVEN observations

    Science.gov (United States)

    Dubinin, Eduard; Fraenz, Markus; McFadden, James; Halekas, Jasper; Epavier, Frank; Connerney, Jack; Brain, David; Jakosky, Bruce; Andrews, David; Barabash, Stas

    2017-04-01

    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 wind and 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, SWIA, MAG 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 solar wind and ionospheric variations, planetary ion fluxes and solar irradiance. It will be shown that that fluxes of planetary ions through different escape channels (trans-terminator fluxes, ion plume, plasma sheet) respond differently on the variations of the different drivers.

  7. Solar Cycle 24 and the Solar Dynamo

    Science.gov (United States)

    Pesnell, W. D.; Schatten, K.

    2007-01-01

    We will discuss the polar field precursor method for solar activity prediction, which predicts cycle 24 will be significantly lower than recent activity cycles, and some new ideas rejuvenating Babcock's shallow surface dynamo. The polar field precursor method is based on Babcock and Leighton's dynamo models wherein the polar field at solar minimum plays a major role in generating the next cycle's toroidal field and sunspots. Thus, by examining the polar fields of the Sun near solar minimum, a forecast for the next cycle's activity is obtained. With the current low value for the Sun's polar fields, this method predicts solar cycle 24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 135 plus or minus 35 (2 sigma), in the 2012-2013 timeframe (equivalent to smoothed Rz near 80 plus or minus 35 [2 sigma]). One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. We discuss unusual behavior in the Sun's polar fields that support this prediction. Normally, the solar precursor method is consistent with the geomagnetic precursor method, wherein geomagnetic variations are thought to be a good measure of the Sun's polar field strength. Because of the unusual polar field, the Earth does not appear to be currently bathed in the Sun's extended polar field (the interplanetary field), hence negating the primal cause behind the geomagnetic precursor technique. We also discuss how percolation may support Babcock's original shallow solar dynamo. In this process ephemeral regions from the solar magnetic carpet, guided by shallow surface fields, may collect to form pores and sunspots.

  8. High Flux Microchannel Receiver Development with Adap-tive Flow Control

    Energy Technology Data Exchange (ETDEWEB)

    Drost, Kevin [Oregon State Univ., Corvallis, OR (United States)

    2015-08-15

    This project is focused on the demonstration of a microchannel-based solar receiver (MSR). The MSR concept consists of using a modular arrangement of arrayed microchannels to heat a working fluid in a concentrating solar receiver, allowing a much higher solar flux on the receiver and consequently a significant reduction in thermal losses, size, and cost.

  9. Detection of solar events

    Science.gov (United States)

    Fischbach, Ephraim; Jenkins, Jere

    2013-08-27

    A flux detection apparatus can include a radioactive sample having a decay rate capable of changing in response to interaction with a first particle or a field, and a detector associated with the radioactive sample. The detector is responsive to a second particle or radiation formed by decay of the radioactive sample. The rate of decay of the radioactive sample can be correlated to flux of the first particle or the field. Detection of the first particle or the field can provide an early warning for an impending solar event.

  10. Recurrence Analysis of Eddy Covariance Fluxes

    Science.gov (United States)

    Lange, Holger; Flach, Milan; Foken, Thomas; Hauhs, Michael

    2015-04-01

    The eddy covariance (EC) method is one key method to quantify fluxes in biogeochemical cycles in general, and carbon and energy transport across the vegetation-atmosphere boundary layer in particular. EC data from the worldwide net of flux towers (Fluxnet) have also been used to validate biogeochemical models. The high resolution data are usually obtained at 20 Hz sampling rate but are affected by missing values and other restrictions. In this contribution, we investigate the nonlinear dynamics of EC fluxes using Recurrence Analysis (RA). High resolution data from the site DE-Bay (Waldstein-Weidenbrunnen) and fluxes calculated at half-hourly resolution from eight locations (part of the La Thuile dataset) provide a set of very long time series to analyze. After careful quality assessment and Fluxnet standard gapfilling pretreatment, we calculate properties and indicators of the recurrent structure based both on Recurrence Plots as well as Recurrence Networks. Time series of RA measures obtained from windows moving along the time axis are presented. Their interpretation is guided by three different questions: (1) Is RA able to discern periods where the (atmospheric) conditions are particularly suitable to obtain reliable EC fluxes? (2) Is RA capable to detect dynamical transitions (different behavior) beyond those obvious from visual inspection? (3) Does RA contribute to an understanding of the nonlinear synchronization between EC fluxes and atmospheric parameters, which is crucial for both improving carbon flux models as well for reliable interpolation of gaps? (4) Is RA able to recommend an optimal time resolution for measuring EC data and for analyzing EC fluxes? (5) Is it possible to detect non-trivial periodicities with a global RA? We will demonstrate that the answers to all five questions is affirmative, and that RA provides insights into EC dynamics not easily obtained otherwise.

  11. Neutrinos do come from solar-fusion

    CERN Multimedia

    1990-01-01

    Results from Kamiokande 11 have given the first convincing evidence that neutrinos are emitted by nuclear fusion in the sun. However, the measured neutrino flux is less than half that predicted by the standard solar model (4 paragraphs).

  12. Magnetic properties of two-dimensional Josephson nets with SNS-junctions

    CERN Document Server

    Ishikaev, S M; Ryazanov, V V; Oboznov, V A

    2002-01-01

    The dependence of the magnetic moment of the square (100 x 100) Josephson nets with the SNS-transitions in the Nb-Cu sub 0 sub . sub 9 sub 5 Al sub 0 sub . 0 sub 5 -Nb on the field is studied through the SQUID-magnetometer. Significant difference in the behaviour during the process of the magnetic flux inlet into the net and its outlet from there was identified thereby. The regular periodical dependence with peaks corresponding to the whole and half number of the flux quanta per one cell is observed on the curve branches, where the increase in the field absolute value takes place. At the same time no visible peculiarities are noted by decrease in the field absolute value. The flux quasi-hydrodynamic motion in the net is explained by significant viscosity of the vortices during their passage through the Josephson junction

  13. Petri Net Tool Overview 1986

    DEFF Research Database (Denmark)

    Jensen, Kurt; Feldbrugge, Frits

    1987-01-01

    This paper provides an overview of the characteristics of all currently available net based tools. It is a compilation of information provided by tool authors or contact persons. A concise one page overview is provided as well....

  14. Understanding Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Salom, Jaume; Widén, Joakim; Candanedo, José

    2011-01-01

    Although several alternative definitions exist, a Net-Zero Energy Building (Net ZEB) can be succinctly described as a grid-connected building that generates as much energy as it uses over a year. The “net-zero” balance is attained by applying energy conservation and efficiency measures...... and by incorporating renewable energy systems. While based on annual balances, a complete description of a Net ZEB requires examining the system at smaller time-scales. This assessment should address: (a) the relationship between power generation and building loads and (b) the resulting interaction with the power grid....... This paper presents and categorizes quantitative indicators suitable to describe both aspects of the building’s performance. These indicators, named LMGI - Load Matching and Grid Interaction indicators, are easily quantifiable and could complement the output variables of existing building simulation tools...

  15. PolicyNet Publication System

    Data.gov (United States)

    Social Security Administration — The PolicyNet Publication System project will merge the Oracle-based Policy Repository (POMS) and the SQL-Server CAMP system (MSOM) into a new system with an Oracle...

  16. KM3NeT

    CERN Multimedia

    KM3NeT is a large scale next-generation neutrino telescope located in the deep waters of the Mediterranean Sea, optimized for the discovery of galactic neutrino sources emitting in the TeV energy region.

  17. Net Neutrality: Background and Issues

    National Research Council Canada - National Science Library

    Gilroy, Angele A

    2006-01-01

    .... The move to place restrictions on the owners of the networks that compose and provide access to the Internet, to ensure equal access and nondiscriminatory treatment, is referred to as "net neutrality...

  18. Petri Nets in Cryptographic Protocols

    DEFF Research Database (Denmark)

    Crazzolara, Federico; Winskel, Glynn

    2001-01-01

    A process language for security protocols is presented together with a semantics in terms of sets of events. The denotation of process is a set of events, and as each event specifies a set of pre and postconditions, this denotation can be viewed as a Petri net. By means of an example we illustrate...... how the Petri-net semantics can be used to prove security properties....

  19. The Economics of Net Neutrality

    OpenAIRE

    Hahn, Robert W.; Wallsten, Scott

    2006-01-01

    This essay examines the economics of "net neutrality" and broadband Internet access. We argue that mandating net neutrality would be likely to reduce economic welfare. Instead, the government should focus on creating competition in the broadband market by liberalizing more spectrum and reducing entry barriers created by certain local regulations. In cases where a broadband provider can exercise market power the government should use its antitrust enforcement authority to police anticompetitiv...

  20. High-heat-flux sensor calibration using calorimetry

    Science.gov (United States)

    Ballestrín, J.; Estrada, C. A.; Rodríguez-Alonso, M.; Pérez-Rábago, C.; Langley, L. W.; Barnes, A.

    2004-08-01

    This paper demonstrates a calorimetric procedure for calibrating high-heat-flux sensors. The results are in agreement with calibrations obtained using black-body radiation. However, the proposed method has the potential of being more accurate than traditional approaches. This new procedure calibrates sensors to measure correctly under conditions of concentrated solar radiation. At present, the thermal balance calibration technique in the laboratory is limited to solar irradiances of approximately 100 kW m-2. The next step is to demonstrate this methodology to higher irradiances under non-laboratory conditions in the CIEMAT solar furnace at Plataforma Solar de Almería.

  1. On the effect of $\\theta_{13}$ on the determination of solar oscillation parameters at KamLAND

    CERN Document Server

    González-Garciá, M Concepción

    2002-01-01

    If the solution to the solar neutrino puzzle falls in the LMA region, KamLAND should be able to measure with good precision the corresponding oscillation parameters after a few years of data taking. Assuming a positive signal, we study their expected sensitivity to the solar parameters (theta_{12},Delta m^2_{21}) when considered in the framework of three-neutrino mixing after taking into account our ignorance on the mixing angle theta_{13}. We find a simple ``scaling'' dependence of the reconstructed theta_{12} range with the value of theta_{13} while the Delta m^2_{12} range is practically unaffected. Our results show that the net effect is approximately equivalent to an uncertainty on the overall neutrino flux normalization of up to sim 10 %.

  2. Solar Plus: A Holistic Approach to Distributed Solar PV

    Energy Technology Data Exchange (ETDEWEB)

    OShaughnessy, Eric J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ardani, Kristen B. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cutler, Dylan S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Margolis, Robert M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-06-08

    Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domestic water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.

  3. Solar Plus: A Holistic Approach to Distributed Solar PV

    Energy Technology Data Exchange (ETDEWEB)

    O' Shaughnessy, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ardani, Kristen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cutler, Dylan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-05-25

    Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domestic water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.

  4. 75 FR 2133 - Construction and Operation of the Quartzsite Solar Energy Project, La Paz County, AZ (DOE/EIS-0440)

    Science.gov (United States)

    2010-01-14

    ...-megawatt (MW) (net) solar-powered generating facility, consisting of a solar field of heliostat mirrors... proposes to construct a 100-MW (net), solar-powered electrical generation facility in La Paz County... tower'' technology to capture the sun's heat to make steam, which would power traditional steam turbine...

  5. Solar cycle changes in the polar solar wind

    Science.gov (United States)

    Coles, W. A.; Rickett, B. J.; Rumsey, V. H.; Kaufman, J. J.; Turley, D. G.; Ananthakrishnan, S.; Armstrong, J. W.; Harmons, J. K.; Scott, S. L.; Sime, D. G.

    1980-01-01

    It is noted that although the 11 year solar cycle was first recognized in 1843, it is still only poorly understood. Further, while there are satisfactory models for the magnetic variations, the underlying physics is still obscure. New observations on the changing three-dimensional form of the solar wind are presented which help relate some of the modulations observed in geomagnetic activity, the ionosphere, and the flux of galactic cosmic rays.

  6. Modeling Net Ecosystem Exchange for Grassland in Central Kazakhstan by Combining Remote Sensing and Field Data

    Directory of Open Access Journals (Sweden)

    Pavel Propastin

    2009-07-01

    Full Text Available Carbon sequestration was estimated in a semi-arid grassland region in Central Kazakhstan using an approach that integrates remote sensing, field measurements and meteorological data. Carbon fluxes for each pixel of 1 × 1 km were calculated as a product of photosynthetically active radiation (PAR and its fraction absorbed by vegetation (fPAR, the light use efficiency (LUE and ecosystem respiration (Re. The PAR is obtained from a mathematical model incorporating Earth-Sun distance, solar inclination, solar elevation angle, geographical position and cloudiness information of localities. The fPAR was measured in field using hemispherical photography and was extrapolated to each pixel by combination with the Normalized Difference Vegetation Index (NDVI obtained by the Vegetation instrument on board the Satellite Pour l’Observation de la Terra (SPOT satellite. Gross Primary Production (GPP of the aboveground and belowground vegetation of 14 sites along a 230 km west-east transect within the study region were determined at the peak of growing season in different land cover types and linearly related to the amount of PAR absorbed by vegetation (APAR. The product of this relationship is LUE = 0.61 and 0.97 g C/MJ APAR for short grassland and steppe, respectively. The Re is estimated using complex models driven by climatic data. Growing season carbon sequestration was calculated for the modelling year of 2004. Overall, the short grassland was a net carbon sink, whereas the steppe was carbon neutral. The evaluation of the modelled carbon sequestration against independent reference data sets proved high accuracy of the estimations.

  7. The Origin and Dynamics of Solar Magnetism

    CERN Document Server

    Thompson, M. J; Culhane, J. L; Nordlund, Å; Solanki, S. K; Zahn, J.-P

    2009-01-01

    The articles collected in this volume present all aspects of solar magnetism: from its origin in the solar dynamo to its evolution and dynamics that create the variability of solar phenomena, its well-known 11-year activity cycle that leads to the ever-changing pattern of sunspots and active regions on the Sun. Several contributions deal with the solar dynamo, the driver of many solar phenomena. Other contributions treat the transport and emergence of the magnetic flux through the outer layers of the Sun. The coupling of magnetic fields from the surface to the solar corona and beyond is also described, together with current studies on the predictability of solar activity. This book is aimed at researchers and graduate students working in solar physics and space science. It provides a full review of our current understanding of solar magnetism by the foremost experts in the field.

  8. Solar Cycle #24 and the Solar Dynamo

    Science.gov (United States)

    Schatten, Kenneth; Pesnell, W. Dean

    2007-01-01

    We focus on two solar aspects related to flight dynamics. These are the solar dynamo and long-term solar activity predictions. The nature of the solar dynamo is central to solar activity predictions, and these predictions are important for orbital planning of satellites in low earth orbit (LEO). The reason is that the solar ultraviolet (UV) and extreme ultraviolet (EUV) spectral irradiances inflate the upper atmospheric layers of the Earth, forming the thermosphere and exosphere through which these satellites orbit. Concerning the dynamo, we discuss some recent novel approaches towards its understanding. For solar predictions we concentrate on a solar precursor method, in which the Sun's polar field plays a major role in forecasting the next cycle s activity based upon the Babcock-Leighton dynamo. With a current low value for the Sun s polar field, this method predicts that solar cycle #24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 130 plus or minus 30 (2 sigma), in the 2013 timeframe. One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. Concomitant effects of low solar activity upon satellites in LEO will need to be considered, such as enhancements in orbital debris. Support for our prediction of a low solar cycle #24 is borne out by the lack of new cycle sunspots at least through the first half of 2007. Usually at the present epoch in the solar cycle (approx. 7+ years after the last solar maximum), for a normal size following cycle, new cycle sunspots would be seen. The lack of their appearance at this time is only consistent with a low cycle #24. Polar field observations of a weak magnitude are consistent with unusual structures seen in the Sun s corona. Polar coronal holes are the hallmarks of the Sun's open field structures. At present, it appears that the polar coronal holes are relatively weak, and there have been many equatorial coronal holes

  9. 26 CFR 1.904(f)-3 - Allocation of net operating losses and net capital losses.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 9 2010-04-01 2010-04-01 false Allocation of net operating losses and net....904(f)-3 Allocation of net operating losses and net capital losses. For rules relating to the allocation of net operating losses and net capital losses, see § 1.904(g)-3T. ...

  10. 29 CFR 4204.13 - Net income and net tangible assets tests.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Net income and net tangible assets tests. 4204.13 Section....13 Net income and net tangible assets tests. (a) General. The criteria under this section are that either— (1) Net income test. The purchaser's average net income after taxes for its three most recent...

  11. Machine learning methods for solar radiation forecasting: a review

    OpenAIRE

    Voyant, C; Notton, G; KALOGIROU S.; M.L. Nivet; C. Paoli; Motte, F.; A. Fouilloy

    2017-01-01

    Forecasting the output power of solar systems is required for the good operation of the power grid or for the optimal management of the energy fluxes occurring into the solar system. Before forecasting the solar systems output, it is essential to focus the prediction on the solar irradiance. The global solar radiation forecasting can be performed by several methods; the two big categories are the cloud imagery combined with physical models, and the machine learning models. In this context, th...

  12. Solar cycle variations in the ionosphere of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Cano, B.; Lester, M.; Witasse, Ol; Blelly, P.L.; Cartacci, M.; Radicella, S.M.; Herraiz, M.

    2016-07-01

    Solar cycle variations in solar radiation create notable changes in the Martian ionosphere, which have been analysed with Mars Express plasma datasets in this paper. In general, lower densities and temperatures of the ionosphere are found during the low solar activity phase, while higher densities and temperatures are found during the high solar activity phase. In this paper, we assess the degree of influence of the long term solar flux variations in the ionosphere of Mars. (Author)

  13. Universal features of Solar Energetic Protons and Events

    Science.gov (United States)

    Giamini, Sigiava; Jiggens, Piers; Daglis, Ioannis A.; Sandberg, Ingmar; Papadimitriou, Constantinos

    2016-07-01

    We present novel results on analysis techniques of Solar Energetic Proton (SEP) measurements and on features of Solar Proton Events (SPEs) based on cross-calibrated GOES measurements. Extensive re-analysis of 265 SPEs reveals the existence of direct associations of SPE Peak flux, duration and fluence to each other, which can be used for SPE statistical and forecasting models. Moreover, we present a novel coherent picture of solar energetic proton fluxes by analyzing 350,000 SEP measurements. The differential proton flux spectra are described in terms of proton flux moments (including spectral integral flux and energy) revealing a coherent picture of fundamental properties of SEPs that also reflects dependencies on the Solar Cycle. The results of these studies will be used for the creation of a new Solar Proton Event Model in the framework of the ESA HERMES project.

  14. SkyNet: A Modular Nuclear Reaction Network Library

    Science.gov (United States)

    Lippuner, Jonas; Roberts, Luke F.

    2017-12-01

    Almost all of the elements heavier than hydrogen that are present in our solar system were produced by nuclear burning processes either in the early universe or at some point in the life cycle of stars. In all of these environments, there are dozens to thousands of nuclear species that interact with each other to produce successively heavier elements. In this paper, we present SkyNet, a new general-purpose nuclear reaction network that evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. SkyNet is free and open source, and aims to be easy to use and flexible. Any list of isotopes can be evolved, and SkyNet supports different types of nuclear reactions. SkyNet is modular so that new or existing physics, like nuclear reactions or equations of state, can easily be added or modified. Here, we present in detail the physics implemented in SkyNet with a focus on a self-consistent transition to and from nuclear statistical equilibrium to non-equilibrium nuclear burning, our implementation of electron screening, and coupling of the network to an equation of state. We also present comprehensive code tests and comparisons with existing nuclear reaction networks. We find that SkyNet agrees with published results and other codes to an accuracy of a few percent. Discrepancies, where they exist, can be traced to differences in the physics implementations.

  15. Standardized Automated CO2/H2O Flux Systems for Individual Research Groups and Flux Networks

    Science.gov (United States)

    Burba, George; Begashaw, Israel; Fratini, Gerardo; Griessbaum, Frank; Kathilankal, James; Xu, Liukang; Franz, Daniela; Joseph, Everette; Larmanou, Eric; Miller, Scott; Papale, Dario; Sabbatini, Simone; Sachs, Torsten; Sakai, Ricardo; McDermitt, Dayle

    2017-04-01

    In recent years, spatial and temporal flux data coverage improved significantly, and on multiple scales, from a single station to continental networks, due to standardization, automation, and management of data collection, and better handling of the extensive amounts of generated data. With more stations and networks, larger data flows from each station, and smaller operating budgets, modern tools are required to effectively and efficiently handle the entire process. Such tools are needed to maximize time dedicated to authoring publications and answering research questions, and to minimize time and expenses spent on data acquisition, processing, and quality control. Thus, these tools should produce standardized verifiable datasets and provide a way to cross-share the standardized data with external collaborators to leverage available funding, promote data analyses and publications. LI-COR gas analyzers are widely used in past and present flux networks such as AmeriFlux, ICOS, AsiaFlux, OzFlux, NEON, CarboEurope, and FluxNet-Canada, etc. These analyzers have gone through several major improvements over the past 30 years. However, in 2016, a three-prong development was completed to create an automated flux system which can accept multiple sonic anemometer and datalogger models, compute final and complete fluxes on-site, merge final fluxes with supporting weather soil and radiation data, monitor station outputs and send automated alerts to researchers, and allow secure sharing and cross-sharing of the station and data access. Two types of these research systems were developed: open-path (LI-7500RS) and enclosed-path (LI-7200RS). Key developments included: • Improvement of gas analyzer performance • Standardization and automation of final flux calculations onsite, and in real-time • Seamless integration with latest site management and data sharing tools In terms of the gas analyzer performance, the RS analyzers are based on established LI-7500/A and LI-7200

  16. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  17. Metal fluxes in the Mersey Narrows

    Directory of Open Access Journals (Sweden)

    J. A. Cole

    2001-01-01

    Full Text Available Surveys of the Mersey estuary in north-west England were undertaken near the mouth of the estuary in the region known as the Mersey Narrows. Tidal fluxes of suspended and dissolved matter, particularly heavy metals, through the Mersey Narrows were investigated. This paper gives results of conducting four intensive cross-sectional surveys of the Narrows, during which currents, salinities, turbidity and water samples were obtained systematically at numerous positions, throughout selected tidal cycles. Over 300 water samples per survey were analysed to yield suspended and dissolved concentrations of the elements As, Cd, Cr, Cu, Hg, Ni, Pb and Zn, at all states of the tide. Suspended solids, concentrations and salinities were also measured. Suspended particulates account for the majority of each element present, except for cadmium, which was present in roughly equal dissolved and suspended fractions. From the tidal current and water quality data, calculations were made of hour-by-hour fluxes of each component, to show the detailed ebb and flow of heavy metals and the net tidal transport of each component. Although some differences between landward transport on the flood tide and seaward transport on the ebb were not significant, the more definite results consistently showed a seawards net transport. For spring tides of high tidal range, there was an indication of an opposite tendency, reducing the seawards transport or even reversing it, for certain suspended components. Keywords: Mersey estuary, surveys, tidal flux, dissolved metals, particulate metals, salinity, suspended particulate matter, suspended solids

  18. Ecosystem-scale VOC fluxes during an extreme drought in a ...

    Science.gov (United States)

    Considerable amounts and varieties of biogenic volatile organic compounds (BVOCs) are exchanged between vegetation and the surrounding air. These BVOCs play key ecological and atmospheric roles that must be adequately represented for accurately modeling the coupled biosphere-atmosphere-climate Earth system. One key uncertainty in existing models is the response of BVOC fluxes to an important global change process: drought. We describe the diurnal and seasonal variation in isoprene, monoterpene and methanol fluxes from a temperate forest ecosystem before, during, and after an extreme 2012 drought event in the Ozark region of the central USA. BVOC fluxes were dominated by isoprene, which attained high emission rates of up to 35.4 mg m-2 h-1 at midday. Methanol fluxes were characterized by net deposition in the morning, changing to a net emission flux through the rest of the daylight hours. Net flux of CO2 reached its seasonal maximum approximately a month earlier than isoprenoid fluxes, which highlights the differential response of photosynthesis and isoprenoid emissions to progressing drought conditions. Nevertheless, both processes were strongly suppressed under extreme drought, although isoprene fluxes remained relatively high compared to reported fluxes from other ecosystems. Methanol exchange was less affected by drought throughout the season, confirming the complex processes driving biogenic methanol fluxes. The fraction of daytime (7-17 h) assimilated carbo

  19. Observations at geosynchronous orbit of a persistent Pc5 geomagnetic pulsation and energetic electron flux modulations

    Directory of Open Access Journals (Sweden)

    T. E. Sarris

    2007-07-01

    Full Text Available A long lasting narrow-band (4–7 mHz Pc5 fluctuation event at geosynchronous orbit is presented through measurements from GOES-8 and GOES-10 and the response of energetic electrons with drift frequencies close to the narrow-band pulsation frequency is monitored through a spectral analysis of flux data from the LANL-SOPA energetic electron instrument. This analysis shows electron flux modulations at the magnetospheric pulsation's frequency as well as at various other frequencies in the Pc5 range, related to the particles' drift-frequencies and their harmonics. A drift resonance effect can be seen, with electron flux modulation becoming more evident in the energy channels of electrons with drift frequencies closer to the wave frequency; however no net increase or decrease in energetic electron flux is observed, indicating that the net energy transfer and transport of electrons is not significant. This Pc5 event has a long duration, being observed for more than a couple of days at geosynchronous orbit over several traversals of the two GOES satellites, and is localized in azimuthal extent. Spectral analysis shows that most of the power is in the transverse components. The frequency of the narrow-band event, as observed at geosynchronous orbit shifts during the time of the event from 7±0.5 mHz to about 4±0.5 mHz. On the ground, CARISMA magnetometers record no distinct narrow-band fluctuation in the magnetic field, and neither does Geotail, which is traversing the outer magnetosphere a few RE further out from geosynchronous orbit, at the same UT and LT that GOES-8 and -10 observe the pulsations, suggesting that that there is no connection to external fluctuations originating in the solar wind. An internal generation mechanism is suggested, such as could be provided by energetic ring current particles, even though conclusive evidence could not be provided for this particular event. Through a statistical study, it is

  20. Net metering and net feed-in tariff for embedded solar PV in South Africa

    CSIR Research Space (South Africa)

    Bischof-Niemz, T

    2015-01-01

    Full Text Available the electricity crisis that South Africa is currently facing in three dimensions: First, it is cheap with effective tariff payments of 0.8-0.9 R/kWh required to stimulate the market; second, it can be implemented fast, because of the distributed nature many...

  1. Weathering of a liquid solar collector

    Science.gov (United States)

    1980-01-01

    Commercially available flate plate hot water solar collector is characterized in report that presents 10 month weathering study of system. Collector efficiency was calculated and plotted from measurements of fluid temperature and flow rate, ambient temperature and solar flux. Windspeed and wind direction were also measured during tests.

  2. Parameter optimization for surface flux transport models

    Science.gov (United States)

    Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie, G. J. D.

    2017-11-01

    Accurate prediction of solar activity calls for precise calibration of solar cycle models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies for what occurs in the interior and provide source terms for coronal models. We use a genetic algorithm to optimize surface flux transport models using National Solar Observatory (NSO) magnetogram data for Solar Cycle 23. This is applied to both a 1D model that inserts new magnetic flux in the form of idealized bipolar magnetic regions, and also to a 2D model that assimilates specific shapes of real active regions. The genetic algorithm searches for parameter sets (meridional flow speed and profile, supergranular diffusivity, initial magnetic field, and radial decay time) that produce the best fit between observed and simulated butterfly diagrams, weighted by a latitude-dependent error structure which reflects uncertainty in observations. Due to the easily adaptable nature of the 2D model, the optimization process is repeated for Cycles 21, 22, and 24 in order to analyse cycle-to-cycle variation of the optimal solution. We find that the ranges and optimal solutions for the various regimes are in reasonable agreement with results from the literature, both theoretical and observational. The optimal meridional flow profiles for each regime are almost entirely within observational bounds determined by magnetic feature tracking, with the 2D model being able to accommodate the mean observed profile more successfully. Differences between models appear to be important in deciding values for the diffusive and decay terms. In like fashion, differences in the behaviours of different solar cycles lead to contrasts in parameters defining the meridional flow and initial field strength.

  3. TimeNET Optimization Environment

    Directory of Open Access Journals (Sweden)

    Christoph Bodenstein

    2015-12-01

    Full Text Available In this paper a novel tool for simulation-based optimization and design-space exploration of Stochastic Colored Petri nets (SCPN is introduced. The working title of this tool is TimeNET Optimization Environment (TOE. Targeted users of this tool are people modeling complex systems with SCPNs in TimeNET who want to find parameter sets that are optimal for a certain performance measure (fitness function. It allows users to create and simulate sets of SCPNs and to run different optimization algorithms based on parameter variation. The development of this tool was motivated by the need to automate and speed up tests of heuristic optimization algorithms to be applied for SCPN optimization. A result caching mechanism is used to avoid recalculations.

  4. Influence of Organic Agriculture on the Net Greenhouse Effect in the Red River Valley, Minnesota

    Science.gov (United States)

    Phillips, R. L.

    2004-12-01

    Fluxes for the suite of biologically-produced greenhouse gases (CH4, N2O and CO2) are strongly influenced by agriculture, yet the influence of organic agriculture on all three gases, which comprise the net greenhouse effect (GHE), is not clear in the context of large-scale agricultural production. Greenhouse gas mitigation potential will depend upon the net balance for all three gases [GHE balance (CO2 equiv.)= CO2 flux+ 23CH4flux + 296N2Oflux]. On-farm, field-scale experiments were performed to test the hypothesis that the net GHE at the soil-atmosphere interface is reduced under organic wheat production, compared with conventional, and that effects vary inter-seasonally. Trace gas fluxes were measured at the soil-atmosphere interface for organic and conventional wheat farms in the Red River Valley, Minnesota, one of the most productive agricultural regions in the US. We utilized 40-60 ha field pairs planted with hard red spring wheat (Triticum aestivum L.). Treatment pairs were located 6km apart and consisted of fields continuously cropped for wheat/soybean/sugar beet production for over 20 yr. Ten random, permanent points were generated for each 8.1 ha sub-plot nested inside each field. Each field pair was similar with respect to crop, climate, cultivation history, tillage, rotation, soil texture, pH, macronutrients, bulk density, and water holding capacity. Differences between treatments for the last five years were soil amendments (compost or urea) and herbicide/fungicide application versus mechanical weed control. We collected gas fluxes at each of the 41 points from April (wheat emergence) until the end of July (maturity) to determine the hourly and seasonally integrated net GHE for each management practice, given similar soil/plant/climatic conditions. Moreover, we analyzed inter-seasonal variability to determine the relationship between wheat phenology and flux under field conditions for soil temperature and moisture (water-filled pore space). The net GHE

  5. Anomalously Weak Solar Convection

    Science.gov (United States)

    Hanasoge, Shravan M.; Duvall, Thomas L.; Sreenivasan, Katepalli R.

    2012-01-01

    Convection in the solar interior is thought to comprise structures on a spectrum of scales. This conclusion emerges from phenomenological studies and numerical simulations, though neither covers the proper range of dynamical parameters of solar convection. Here, we analyze observations of the wavefield in the solar photosphere using techniques of time-distance helioseismology to image flows in the solar interior. We downsample and synthesize 900 billion wavefield observations to produce 3 billion cross-correlations, which we average and fit, measuring 5 million wave travel times. Using these travel times, we deduce the underlying flow systems and study their statistics to bound convective velocity magnitudes in the solar interior, as a function of depth and spherical- harmonic degree l..Within the wavenumber band l convective velocities are 20-100 times weaker than current theoretical estimates. This constraint suggests the prevalence of a different paradigm of turbulence from that predicted by existing models, prompting the question: what mechanism transports the heat flux of a solar luminosity outwards? Advection is dominated by Coriolis forces for wavenumbers l convection may be quasi-geostrophic. The fact that isorotation contours in the Sun are not coaligned with the axis of rotation suggests the presence of a latitudinal entropy gradient.

  6. Methane Fluxes from Subtropical Wetlands

    Science.gov (United States)

    DeLucia, N.; Gomez-Casanovas, N.; Bernacchi, C.

    2013-12-01

    It is well documented that green house gas concentrations have risen at unequivocal rates since the industrial revolution but the disparity between anthropogenic sources and natural sources is uncertain. Wetlands are one example of a natural ecosystem that can be a substantial source or sink for methane (CH4) depending on climate conditions. Due to strict anaerobic conditions required for CH4-generating microorganisms, natural wetlands are one of the main sources for biogenic CH4. Although wetlands occupy less than 5% of total land surface area, they contribute approximately 20% of total CH4 emissions to the atmosphere. The processes regulating CH4 emissions are sensitive to land use and management practices of areas surrounding wetlands. Variation in adjacent vegetation or grazing intensity by livestock can, for example, alter CH4 fluxes from wetland soils by altering nutrient balance, carbon inputs and hydrology. Therefore, understanding how these changes will affect wetland source strength is essential to understand the impact of wetland management practices on the global climate system. In this study we quantify wetland methane fluxes from subtropical wetlands on a working cattle ranch in central Florida near Okeechobee Lake (27o10'52.04'N, 81o21'8.56'W). To determine differences in CH4 fluxes associated with land use and management, a replicated (n = 4) full factorial experiment was designed for wetlands where the surrounding vegetation was (1) grazed or un-grazed and (2) composed of native vegetation or improved pasture. Net exchange of CH4 and CO2 between the land surface and the atmosphere were sampled with a LICOR Li-7700 open path CH4 analyzer and Li-7500A open path CO2/H20 analyzer mounted in a 1-m3 static gas-exchange chamber. Our results showed and verified that CH4 emissions from subtropical wetlands were larger when high soil moisture was coupled with high temperatures. The presence of cattle only amplified these results. These results help quantify

  7. Implementing NetScaler VPX

    CERN Document Server

    Sandbu, Marius

    2014-01-01

    An easy-to-follow guide with detailed step-by step-instructions on how to implement the different key components in NetScaler, with real-world examples and sample scenarios.If you are a Citrix or network administrator who needs to implement NetScaler in your virtual environment to gain an insight on its functionality, this book is ideal for you. A basic understanding of networking and familiarity with some of the different Citrix products such as XenApp or XenDesktop is a prerequisite.

  8. Net4Care PHMR Library

    DEFF Research Database (Denmark)

    2014-01-01

    The Net4Care PHMR library contains a) A GreenCDA approach for constructing a data object representing a PHMR document: SimpleClinicalDocument, and b) A Builder which can produce a XML document representing a valid Danish PHMR (following the MedCom profile) document from the SimpleClinicalDocument......The Net4Care PHMR library contains a) A GreenCDA approach for constructing a data object representing a PHMR document: SimpleClinicalDocument, and b) A Builder which can produce a XML document representing a valid Danish PHMR (following the MedCom profile) document from the Simple...

  9. Pro DLR in NET 4

    CERN Document Server

    Wu, Chaur

    2011-01-01

    Microsoft's Dynamic Language Runtime (DLR) is a platform for running dynamic languages such as Ruby and Python on an equal footing with compiled languages such as C#. Furthermore, the runtime is the foundation for many useful software design and architecture techniques you can apply as you develop your .NET applications. Pro DLR in .NET 4 introduces you to the DLR, showing how you can use it to write software that combines dynamic and static languages, letting you choose the right tool for the job. You will learn the core DLR components such as LINQ expressions, call sites, binders, and dynami

  10. Hierarchies in Coloured Petri Nets

    DEFF Research Database (Denmark)

    Huber, Peter; Jensen, Kurt; Shapiro, Robert M.

    1991-01-01

    The paper shows how to extend Coloured Petri Nets with a hierarchy concept. The paper proposes five different hierarchy constructs, which allow the analyst to structure large CP-nets as a set of interrelated subnets (called pages). The paper discusses the properties of the proposed hierarchy...... constructs, and it illustrates them by means of two examples. The hierarchy constructs can be used for theoretical considerations, but their main use is to describe and analyse large real-world systems. All of the hierarchy constructs are supported by the editing and analysis facilities in the CPN Palette...

  11. Simulating solar MHD

    Directory of Open Access Journals (Sweden)

    M. Schüssler

    Full Text Available Two aspects of solar MHD are discussed in relation to the work of the MHD simulation group at KIS. Photospheric magneto-convection, the nonlinear interaction of magnetic field and convection in a strongly stratified, radiating fluid, is a key process of general astrophysical relevance. Comprehensive numerical simulations including radiative transfer have significantly improved our understanding of the processes and have become an important tool for the interpretation of observational data. Examples of field intensification in the solar photosphere ('convective collapse' are shown. The second line of research is concerned with the dynamics of flux tubes in the convection zone, which has far-reaching implications for our understanding of the solar dynamo. Simulations indicate that the field strength in the region where the flux is stored before erupting to form sunspot groups is of the order of 105 G, an order of magnitude larger than previous estimates based on equipartition with the kinetic energy of convective flows.

    Key words. Solar physics · astrophysics and astronomy (photosphere and chromosphere; stellar interiors and dynamo theory; numerical simulation studies.

  12. Effects of biomass burning on climate, accounting for heat and moisture fluxes, black and brown carbon, and cloud absorption effects

    Science.gov (United States)

    Jacobson, Mark Z.

    2014-07-01

    This paper examines the effects on climate and air pollution of open biomass burning (BB) when heat and moisture fluxes, gases and aerosols (including black and brown carbon, tar balls, and reflective particles), cloud absorption effects (CAEs) I and II, and aerosol semidirect and indirect effects on clouds are treated. It also examines the climate impacts of most anthropogenic heat and moisture fluxes (AHFs and AMFs). Transient 20 year simulations indicate BB may cause a net global warming of 0.4 K because CAE I ( 32% of BB warming), CAE II, semidirect effects, AHFs ( 7%), AMFs, and aerosol absorption outweigh direct aerosol cooling and indirect effects, contrary to previous BB studies that did not treat CAEs, AHFs, AMFs, or brown carbon. Some BB warming can be understood in terms of the anticorrelation between instantaneous direct radiative forcing (DRF) changes and surface temperature changes in clouds containing absorbing aerosols. BB may cause 250,000 (73,000-435,000) premature mortalities/yr, with >90% from particles. AHFs from all sources and AMFs + AHFs from power plants and electricity use each may cause a statistically significant +0.03 K global warming. Solar plus thermal-IR DRFs were +0.033 (+0.027) W/m2 for all AHFs globally without (with) evaporating cooling water, +0.009 W/m2 for AMFs globally, +0.52 W/m2 (94.3% solar) for all-source BC outside of clouds plus interstitially between cloud drops at the cloud relative humidity, and +0.06 W/m2 (99.7% solar) for BC inclusions in cloud hydrometeor particles. Modeled post-1850 biomass, biofuel, and fossil fuel burning, AHFs, AMFs, and urban surfaces accounted for most observed global warming.

  13. Model for Cumulative Solar Heavy Ion Energy and LET Spectra

    Science.gov (United States)

    Xapsos, Mike; Barth, Janet; Stauffer, Craig; Jordan, Tom; Mewaldt, Richard

    2007-01-01

    A probabilistic model of cumulative solar heavy ion energy and lineary energy transfer (LET) spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions.

  14. Solar Wind Earth Exchange Project (SWEEP)

    Science.gov (United States)

    2016-10-28

    highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the...Newton, an X-ray astronomical observatory. We use OMNI solar wind conditions, heavy ion composition data from ACE, the Hodges neutral hydrogen model...of SWEEP was to compare theoretical models of X-ray emission in the terrestrial magnetosphere caused by the Solar Wind Charge Exchange

  15. Suprathermal Charged Particle Acceleration by Small-scale Flux Ropes.

    Science.gov (United States)

    Zank, G. P.; le Roux, J. A.; Webb, G. M.

    2015-12-01

    We consider different limits of our recently developed kinetic transport theory to investigate the potential of super-Alvenic solar wind regions containing several small-scale flux ropes to explain the acceleration of suprathermal ions to power-law spectra as observations show. Particle acceleration is modeled in response to flux-rope activity involving contraction, merging (reconnection), and collisions in the limit where the particle gyoradius is smaller than the characteristic flux-rope scale length. The emphasis is mainly on the statistical variance in the electric fields induced by flux-rope dynamics rather than on the mean electric field induced by multiple flux ropes whose acceleration effects are discussed elsewhere. Our steady-state analytical solutions suggest that particle drift acceleration by flux ropes, irrespective of whether displaying incompressible or compressible behavior, can yield power laws asymptotically at higher energies whereas an exponential spectral rollover results asymptotically when field-aligned guiding center motion acceleration occur by reconnection electric fields from merging flux ropes. This implies that at sufficiently high particle energies, drift acceleration might dominate. We also expect compressive flux ropes to yield harder power-law spectra than incompressible flux ropes. Preliminary results will be discussed to illustrate how particle acceleration might be affected when both diffusive shock and small-scale flux acceleration occur simultaneously at interplanetary shocks.

  16. Mars MetNet Mission - Martian Atmospheric Observational Post Network

    Science.gov (United States)

    Hari, Ari-Matti; Haukka, Harri; Aleksashkin, Sergey; Arruego, Ignacio; Schmidt, Walter; Genzer, Maria; Vazquez, Luis; Siikonen, Timo; Palin, Matti

    2017-04-01

    A new kind of planetary exploration mission for Mars is under development in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested. 1. MetNet Lander The MetNet landing vehicles are using an inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used. This way the ratio of the payload mass to the overall mass is optimized. The landing impact will burrow the payload container into the Martian soil providing a more favorable thermal environment for the electronics and a suitable orientation of the telescopic boom with external sensors and the radio link antenna. It is planned to deploy several tens of MNLs on the Martian surface operating at least partly at the same time to allow meteorological network science. 2. Strawman Scientific Payload The strawman payload of the two MNL precursor models includes the following instruments: Atmospheric instruments: - MetBaro Pressure device - MetHumi Humidity device - MetTemp Temperature sensors Optical devices: - PanCam Panoramic - MetSIS Solar irradiance sensor with OWLS optical wireless system for data transfer - DS Dust sensor Composition and Structure Devices: Tri-axial magnetometer MOURA Tri-axial System Accelerometer The descent processes dynamic properties are monitored by a special 3-axis

  17. Validation of Empirical and Semi-empirical Net Radiation Models versus Observed Data for Cold Semi-arid Climate Condition

    Directory of Open Access Journals (Sweden)

    aliakbar sabziparvar

    2017-03-01

    Full Text Available Introduction: Solar Net Radiation (Rn is one of the most important component which influences soil heat flux, evapotranspiration rate and hydrological cycle. This parameter (Rn is measured based on the difference between downward and upward shortwave (SW and longwave (LW irradiances reaching the Earth’s surface. Field measurements of Rn are scarce, expensive and difficult due to the instrumental maintenance. As a result, in most research cases, Rn is estimated by the empirical, semi-empirical and physical radiation models. Almorox et al. (2008 suggested a net radiation model based on a linear regression model by using global solar radiation (Rs and sunshine hours. Alados et al. (2003 evaluated the relation between Rn and Rs for Spain. They showed that the models based on shortwave radiation works perfect in estimating solar net radiation. In another work, Irmak et al. (2003 presented two empirical Rn models, which worked with the minimum numbers of weather parameters. They evaluated their models for humid, dry, inland and coastal regions of the United States. They concluded that both Rn models work better than FAO-56 Penman-Monteith model. Sabziparvar et al. (2016 estimated the daily Rn for four climate types in Iran. They examined various net radiation models namely: Wright, Basic Regression Model (BRM, Linacre, Berliand, Irmak, and Monteith. Their results highlighted that on regional averages, the linear BRM model has the superior performance in generating the most accurate daily ET0. They also showed that for 70% of the study sites, the linear Rn models can be reliable candidates instead of sophisticated nonlinear Rn models. Having considered the importance of Rn in determining crop water requirement, the aim of this study is to obtain the best performance Rn model for cold semi-arid climate of Hamedan. Materials and Methods: We employed hourly and daily weather data and Rn data, which were measured during December 2011 to June 2013 in

  18. Results from atmospheric and solar neutrinos experiments

    CERN Document Server

    Kearns, E T

    2001-01-01

    This paper is a summary of non-accelerator neutrino physics, concentrating on the latest experimental results using atmospheric and solar neutrinos to study neutrino oscillation. Neutrino oscillation is well-established in atmospheric neutrinos and current efforts aim to better measure and understand the phenomenon. Solar neutrinos continue to present an unsolved puzzle, with the latest data from Super-Kamiokande exhibiting a large flux deficit, but no significant day-night flux difference or spectral distortion. For both atmospheric and solar neutrinos, the data prefers oscillation between active flavors ( nu /sub e/ nu /sub mu / nu /sub tau /) and disfavors a 2-flavor oscillation to nu -sterile as the primary effect.

  19. D.NET case study

    International Development Research Centre (IDRC) Digital Library (Canada)

    lremy

    developing products, marketing tools and building capacity of the grass root telecentre workers. D.Net recognized that it had several ideas worth developing into small interventions that would make big differences, but resource constraints were a barrier for scaling-up these initiatives. More demands, limited resources.

  20. Surgery for GEP-NETs

    DEFF Research Database (Denmark)

    Knigge, Ulrich; Hansen, Carsten Palnæs

    2012-01-01

    Surgery is the only treatment that may cure the patient with gastroentero-pancreatic (GEP) neuroendocrine tumours (NET) and neuroendocrine carcinomas (NEC) and should always be considered as first line treatment if R0/R1 resection can be achieved. The surgical and interventional procedures for GEP...