Showing papers on "Solar constant published in 2015"

Modelling solar potential in the urban environment: State-of-the-art review

Abstract: Cityscapes provide a complex environment, where solar radiation is unevenly distributed, especially since urban features started to propagate more and more vertically. Due to the dynamic overshadowing effects present on building surfaces, quantifying these phenomena is essential for predicting reductions in solar radiation availability that can significantly affect potential for solar energy use. Numerical radiation algorithms coupled with GIS tools are a pathway to evaluate those complex effects. Accurate representation of the terrain, vegetation canopy and building structures allows better estimation of shadow patterns. Higher spatial and temporal resolutions deliver more detailed results, but models must compromise between accuracy and computation time. In this paper, models ranging from simple 2D visualization and solar constant methods, to more sophisticated 3D representation and analysis, are reviewed. Web-based solar maps, which rely on the previous features to successfully communicate the benefits of the solar resource to the public and support in the policy-making process, are also addressed.

The evolution of habitable climates under the brightening Sun

Abstract: On water-dominated planets, warming from increased solar insolation is strongly amplified by the water vapor greenhouse feedback. As the Sun brightens due to stellar evolution, Earth will become uninhabitable due to rising temperatures. Here we use a modified version of the Community Earth System Model from the National Center for Atmospheric Research to study Earth under intense solar radiation. For small (≤10%) increases in the solar constant (S0), Earth warms nearly linearly with climate sensitivities of ~1 K/(W m−2) and global mean surface temperatures below 310 K. However, an abrupt shift in climate is found as the solar constant is increased to +12.5% S0. Here climate sensitivity peaks at ~6.5 K/(W m−2), while global mean surface temperatures rise above 330 K. This climatic transition is associated with a fundamental change to the radiative-convective state of the atmosphere. Hot, moist climates feature both strong solar absorption and inefficient radiative cooling in the low atmosphere, thus yielding net radiative heating of the near-surface layers. This heating forms an inversion that effectively shuts off convection in the boundary layer. Beyond the transition, Earth continues to warm but with climate sensitivities again near unity. Conditions conducive to significant water loss to space are not found until +19% S0. Earth remains stable against a thermal runaway up to at least +21% S0, but at that point, global mean surface temperatures exceed 360 K, and water loss to space becomes rapid. Water loss of the oceans from a moist greenhouse may preclude a thermal runaway.

Recent Advances on Solar Global Magnetism and Variability

Abstract: We discuss recent observational, theoretical and numerical progress made in understanding the solar global magnetism and its short and long term variability. We discuss the physical process thought to be at the origin of the solar magnetic field and its 22-yr cycle, namely dynamo action, and the nonlinear interplay between convection, rotation, radiation and magnetic field, yielding modulations of the solar constant or of the large scale flows such as the torsional oscillations. We also discuss the role of the field parity and dynamo families in explaining the complex multipolar structure of the solar global magnetic field. We then present some key MHD processes acting in the deep radiative interior and discuss the probable topology of a primordial field there. Finally we summarize how helioseismology has contributed to these recent advances and how it could contribute to resolving current unsolved problems in solar global dynamics and magnetism.

The Atacama Surface Solar Maximum

Abstract: Solar radiation reaching Earth’s surface is one of the major drivers of climate dynamics. By setting the surface energy balance, downwelling solar radiation indirectly heats the atmosphere and controls the hydrological cycle. Besides its critical importance as a physical mechanism for driving climate and weather, solar radiation has attracted interest as a potentially major source of energy for human activities.For a given latitude, solar radiation at Earth’s surface depends mostly on the composition along the atmospheric path. Since the early twentieth century, major astronomical observatories have led the search for the best places for observation from Earth, which presents a similar problem to the one of finding the maximum of solar radiation at the surface. In particular, Mount Montezuma in the Atacama Desert, Chile, was identified by the pioneers of solar observation as an ideal place to conduct the search for variations of the solar constant estimated from Earth’s surface.By using available ...

Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols

Abstract: The climatic effects of Solar Radiation Management (SRM) geoengineering have been often modeled by simply reducing the solar constant. This is most likely valid only for space sunshades and not for atmosphere and surface based SRM methods. In this study, a global climate model is used to evaluate the differences in the climate response to SRM by uniform solar constant reduction and stratospheric aerosols. Our analysis shows that when global mean warming from a doubling of CO2 is nearly cancelled by both these methods, they are similar when important surface and tropospheric climate variables are considered. However, a difference of 1 K in the global mean stratospheric (61–9.8 hPa) temperature is simulated between the two SRM methods. Further, while the global mean surface diffuse radiation increases by ~23 % and direct radiation decreases by about 9 % in the case of sulphate aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (~1.0 %) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2 % decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (~8 %) and net primary productivity (~3 %). Based on our results we conclude that the climate states produced by a reduction in solar constant and addition of aerosols into the stratosphere can be considered almost similar except for two important aspects: stratospheric temperature change and the consequent implications for the dynamics and the chemistry of the stratosphere and the partitioning of direct versus diffuse radiation reaching the surface. Further, the likely dependence of global hydrological cycle response on aerosol particle size and the latitudinal and height distribution of aerosols is discussed.

On the constancy of the diameter of the sun during the rising phase of solar cycle 24

Abstract: The potential relationship between solar activity and changes in solar diameter remains the subject of debate and requires both models and measurements with sufficient precision over long periods of time. Using the PICARD instruments, we carried out precise measurements of variations in solar diameter during the rising phase of solar cycle 24. From new correction methods we found changes in PICARD space telescope solar radius amplitudes that were less than ±20 mas (i.e. ±14.5 km) for the years 2010–2011. Moreover, PICARD ground-based telescope solar radius amplitudes are smaller than ±50 mas from 2011 to 2014. Our observations could not find any direct link between solar activity and significant fluctuations in solar radius, considering that the variations, if they exist, are included within this range of values. Further, the contribution of solar radius fluctuations is low with regard to variations in total solar irradiance. Indeed, we find a small variation of the solar radius from space measurements with a typical periodicity of 129.5 days, with ±6.5 mas variation.

On the Determination and Constancy of the Solar Oblateness

Abstract: The equator-to-pole radius difference (Δr=R eq−R pol) is a fundamental property of our star, and understanding it will enrich future solar and stellar dynamical models. The solar oblateness (Δ⊙) corresponds to the excess ratio of the equatorial solar radius (R eq) to the polar radius (R pol), which is of great interest for those working in relativity and different areas of solar physics. Δr is known to be a rather small quantity, where a positive value of about 8 milli-arcseconds (mas) is suggested by previous measurements and predictions. The Picard space mission aimed to measure Δr with a precision better than 0.5 mas. The Solar Diameter Imager and Surface Mapper (SODISM) onboard Picard was a Ritchey–Chretien telescope that took images of the Sun at several wavelengths. The SODISM measurements of the solar shape were obtained during special roll maneuvers of the spacecraft by 30° steps. They have produced precise determinations of the solar oblateness at 782.2 nm. After correcting measurements for optical distortion and for instrument temperature trend, we found a solar equator-to-pole radius difference at 782.2 nm of 7.9±0.3 mas (5.7±0.2 km) at one σ. This measurement has been repeated several times during the first year of the space-borne observations, and we have not observed any correlation between oblateness and total solar irradiance variations.

On the variation of solar radius in rotation cycles

Abstract: The Date Compensated Discrete Fourier Transform and CLEANest algorithm are used to study the temporal variations of the solar radius observed at Rio de Janeiro Observatory from 1998 March 2 to 2009 November 6. The CLEANest spectra show several significant periodicities around 400, 312, 93.5, 86.2, 79.4, 70.9, 53.2, and 26.3 days. Then, combining the data on the daily solar radius measured at Calern Observatory and Rio de Janeiro Observatory and the corresponding daily sunspot areas, we study the short-term periodicity of the solar radius and the role of magnetic field in the variation of the solar radius. The rotation period of the daily solar radius is determined to be statistically significant. Moreover, its temporal evolution is anti-phase with that of sunspot activity, and it is found anti-phase with solar activity. Generally, the stronger solar activity is, the more obvious is the anti-phase relation of radius with solar activity. This indicates that strong magnetic fields have a greater inhibitive effect than weak magnetic fields on the variation of the radius.

Automotive solar constant temperature system

Abstract: The invention relates to a solar constant temperature system. The solar constant temperature system comprises a storage battery (1), a control system (2), a photovoltatic solar panel (3), a semiconductor air conditioner (4), a water tank (5), a condenser (6) and a water cooling driving pump (7) and is characterized in that positive and negative outgoing wirings of the storage battery (1) are connected to the control system (2); an electric quantity sensor is arranged inside the storage battery (1); the control system (2) controls the storage battery (1) to output currents or controls the storage battery (1) to receive currents to be stored according to electric quantity signals of the storage battery (1). The solar constant temperature system enables an air conditioning system in the automobile to be intelligentialized and relieves the severe environment inside a passenger cabin when the automobile starts in hot summer; fully utilizes the solar energy and the storage battery on the automobile to coordinately supply energy for the constant temperature system; improves the heat dissipation effect of the semiconductor air conductor and improves the refrigerating efficiency of the semiconductor; improves a traditional radiator, utilizes the radiator in a time division mode and improves the utilization rate.

Calibration Device Development for Spherical Solar Radiation Sensors

Abstract: Measuring the solar radiation received by a plant canopy is necessary to analyze its physiological aspects. A spherical photodiode has been developed for this purpose. However, a horizontally set calibrated solarimeter using a flat type sensor cannot be used for calibration because it must remain unaffected by the cosine law. Therefore, an inexpensive automatic tracking solar disk system has been developed for the calibration of a spherical type solarimeter. A calibrated solarimeter was mounted on the tracking system and was inclined according to the altitude and the declination angle of the location on the day of the experiment. The system calibrated all four spherical solarimeters with high correlation coefficients . Some data exceed the so-called solar constant, which is measured similarly, but outside of the earth atmospheric layer because the device developed this time measured hemispherical solar radiation normal to the sun disk. Similar data were reported even from horizontal measurements.

Influences of Greenhouse Gas, Sea Surface Temperature, Solar Constant, and Volcanic Activity on Surface Temperature in China

Abstract: Using the Community Atmospheric Model Version 3.1(CAM3.1) of NCAR, the influence of greenhouse gas, global sea surface temperature(SST), solar constant, and volcanic activity on surface temperature is studied. The results show that increase of greenhouse gas and global SST contributes to the warming trend. Over recent 100 years, annual surface temperature in China undergoes two decadal oscillations and increases. China experienced two warm-periods during 1940 s and 1990 s respectively and two relative cold periods during 1910 s and the period of 1950s-1960 s. The variations of surface temperate over China, solar constant and SST have an oscillation period of 60 years, two decadal oscillations of surface temperature over China are induced by two decadal oscillations of solar constant and SST, the variation of surface temperature lagged behind of solar constant and SST. The volcanic activities before 1920 s and after 1960 s are one of the reasons of cooling trend during 1910 s and 1960s-1980 s.

Value of Solar Array Technology Advancement

Abstract: In making investment decisions for spacecraft technology development, it is critical to understand how such advances impact spacecraft budgets such as mass, volume, and power. Beneficial effects on spacecraft budgets translate into improved payload capability and/or reduced spacecraft cost. Reduced cost and improved capability are central goals for the space enterprise, including both military and commercial entities. This work systematically evaluates the effect of increasing solar array performance on spacecraft mass, volume, power, and cost budgets for three assumed missions: low Earth orbit (3 kW), medium Earth orbit (10 kW), and geostationary Earth orbit (20 kW). Solar array metrics used to quantify improved solar array performance are specific power (watts per kilogram), stowed power density (kilowatts per cubic meter), and solar cell efficiency (percent). Changes in solar array metrics are translated into the effect on spacecraft mass, volume, power, and cost budgets for the three assumed missions....

Solar constant temperature barbecuing device

Abstract: The invention provides a solar constant temperature barbecuing device The solar constant temperature barbecuing device comprises a solar heat collection tube, a light condenser plate and a support; the light condenser plate is arranged on the support; the solar heat collection tube is connected with the support and arranged on the inner side of the light condenser plate; the solar constant temperature barbecuing device also comprises a heat accumulation tube which is arranged on the inner side of the solar heat collection tube and filled with heat accumulation materials; the cross section of the light condenser plate is in a U shape; the solar heat collection tube is arranged in a U-shape opening of the light condenser plate; the heat accumulation materials are inorganic salt composite phase change heat accumulation materials or expanded graphite composite phase change heat accumulation materials According to the solar constant temperature barbecuing device, the energy regulation and the temperature control are performed on the solar barbecuing process through the phase change heat accumulation materials and accordingly the defect of the nonuniform heat of the solar energy is overcome and harmful materials such as heterocyclic amines which are harmful to the health of human bodies can be effectively reduced

Optimization of Stationary Flat-Plate Solar Collectors

Abstract: The optimum design of stationary flat-plate solar collectors is considered using the game theory approach for multiple objectives. The clear day solar beam radiation and diffuse radiation at the location of the solar collector are estimated. Three objectives are considered in the optimization problem formulation: maximization of the annual average incident solar energy, maximization of the lowest month incident solar energy and minimization of the cost. The game theory solution represents the best compromise in terms of the supercriterion selected. Because some design parameters such as solar constant, altitude, typical day of each month and most of the design variables are not precisely known, a probabilistic approach is also proposed in this work. The results obtained by the determinist and probabilistic approaches are compared. It is found that the absolute value of each objective function decreases with an increase in either the probability of constraint satisfaction or the coefficient of variation of the random variables. This work represents the first work aimed at the application of multi-objective optimization strategy, particularly the game theory approach, for the solution of the solar collector design problem.Copyright © 2015 by ASME

SORCE Level 3 Total Solar Irradiance Daily Average V016

Abstract: the total solar irradiance tsi data set sor3tsid contains the total solar irradiance a k a solar constant data collected by the total irradiance monitor tim instrument covering the full wavelength spectrum averaged at daily intervals the data are normalized to one astronomical unit 1 au the tim instrument measures the total solar irradiance tsi monitoring changes in incident sunlight to the earth s atmosphere using an ambient temperature active cavity radiometer to a designed absolute accuracy of 100 parts per million ppm 1 ppm 0 0001 at 1 sigma and a precision and long term relative accuracy of 10 ppm per year due to the small size these data and to maximize ease of use to end users each delivered tsi product contains science results for the entire mission updates to level 3 tsi data occur monthly in order to reduce repeated delivery of data

Method of measuring solar activity in medium-term weather-climate forecasts

Abstract: FIELD: physics.SUBSTANCE: method includes monitoring current solar activity; predicting the area of cloud cover which is in anticorrelation with the number of sun spots and in correlation with flares of total flux of radiant solar energy (solar constant); predicting temperature anomalies of ground air, taking into account said solar data, as well as known data on the effect of changes in total cloud cover on variation of temperature anomalies of ground air.EFFECT: high accuracy and early forecast of temperature anomalies of ground air.2 cl, 3 dwg

Optimal design of stationary flat-plate solar collectors : deterministic and probabilistic approaches

Abstract: Because of the soaring energy prices, many countries have shown an increased interest in the utilization of solar energy The optimization of the solar energy collector design plays a critical role in the efficient collection of solar energy Flat-plate collectors can be designed in applications that require energy delivery at moderate temperatures (up to 100 ◦ C above ambient temperature) These collectors use both beam and diffuse solar radiation, and do not need to track the sun They are simple to manufacture and install with relatively low maintenance cost which make this kind of solar collectors more popular The design of a flat-plate solar collector embraces many relationships among the collector parameters, field parameters and solar radiation data at any given location The shading decreases the incident energy on collector plane of the field The multi-objective optimum design of stationary flat-plate solar collectors is presented in this work The clear day solar beam radiation and diffuse radiation at the location of the solar collector (Miami) are estimated The maximization of the annual average incident solar energy, maximization of the lowest month incident solar energy and minimization of the cost are considered as objectives The game theory methodology is used for the solution of the three objective problems to find the best compromise solution The sensitivity analysis with respect to the design variables and the solar constant are conducted to find the relative influence of the parameters on the design The multi-objective optimum design of stationary flat-plate solar collectors under probabilistic uncertainty is also considered The three objectives stated earlier are considered in the optimization problem The solar constant, altitude, typical day of each month and most of the design variables have been treated as probabilistic variables following normal distribution The game theory methodology is used for the solution of the three objective constrained optimization problems to find a balanced solution A parametric study is conducted with respect to changes in the standard deviation of the mean values of design variables and probability of constraint satisfaction This work represents a novel application of the multi-objective optimization strategy, including probabilistic approach, for the solution of the solar collector design problem The present study is expected to help designers in creating optimized solar collectors based on any specified requirements

General trends in the changes of indices of solar activity in the late xx - early xxi century

Abstract: The analysis of the observations of solar activity indexes SSN (NOAA Sunspot Numbers), the radio flux at a wavelength of 10.7 cm (F10.7) and the solar constant (TSI) during the cycles 22 - 24 is presented. We found a decrease of the observed values of the SSNobs which was calculated with SSNsyn (using regression relationships between SSN and F10.7) after 1990 year on 20 - 25% instead of 35%, as was previously assumed. The changes in characteristics of the most popular index, SSN, such as decrease in the number of sunspots, the reduction of the magnetic field in small and medium-sized spots are not in full compliance with the proposed scenario of solar activity predicted by radio flux F10.7 in the cycles 23 and 24, and cannot be fully explained by the influence on the SSN values of additional minimum of 50 - 70 year cycle. We have also showed that the observed changes of SSN lead to a slight increase of the solar constant TSI during the cycles 23 - 24 compared to the cycle 22.