Showing papers on "Solar constant published in 2011"

A new, lower value of total solar irradiance: Evidence and climate significance

Abstract: [1] The most accurate value of total solar irradiance during the 2008 solar minimum period is 1360.8 ± 0.5 W m−2 according to measurements from the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This value is significantly lower than the canonical value of 1365.4 ± 1.3 W m−2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher irradiance values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM's lower solar irradiance value is not a change in the Sun's output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates.

Holocene climate variability of the Norwegian Atlantic Current during high and low solar insolation forcing

Abstract: [1] A high-resolution sediment core from the Voring Plateau has been studied to document the centennial to millennial variability of the surface water conditions during the Holocene Climate Optimum (HCO) and the late Holocene period (LHP) in order to evaluate the effects of solar insolation on surface ocean climatology. Quantitative August summer sea surface temperatures (SSSTs) with a time resolution of 2–40 years are reconstructed by using three different diatom transfer function methods. Spectral- and scale-space methods are applied to the records to explore the variability present in the time series at different time scales. The SSST development in core MD95-2011 shows a delayed response to Northern Hemisphere maximum summer insolation at ∼11,000 years B.P. The record shows the maximum SSST of the HCO to be from 7.3 to 8.9 kyr B.P., which implies that the site was located in the regional warm water pool removed from the oceanic fronts and Arctic waters. Superimposed on the general cooling trend are higher-frequency variabilities at time scales of 80–120, 210–320, 320–640, and 640–1280 years. The climate variations at the time scale of 320–640 years are documented both for periods of high and low solar orbital insolation. We found evidence that the submillennial-scale mode of variability (640–900 years) in SSST evident during the LHP is directly associated with varying solar forcing. At the shorter scale of 260–450 years, the SSST during the LHP displays a lagged response to solar forcing with a phase-locked behavior indicating the existence of a feedback mechanism in the climate system triggered by variations in the solar constant as well as the role of the thermal inertia of the ocean. The abruptness of the cooling events in the LHP, especially pronounced during the onsets of the Holocene Cold Period I (approximately 2300 years B.P.) and the Little Ice Age (approximately 550 years B.P.), can be explained by a shutdown of deep convection in the Nordic Seas in response to negative solar insolation anomalies. These cooling events are on the order of 1.5°C.

The Sun's small-scale magnetic elements in Solar Cycle 23

Abstract: With the unique database from Michelson Doppler Imager aboard the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million small-scale magnetic elements are selected, and the following results are unclosed. (1) The quiet regions dominated the Sun's magnetic flux for about 8 years in the 12.25 year duration of Cycle 23. They contributed (0.94 - 1.44) $\times 10^{23}$ Mx flux to the Sun from the solar minimum to maximum. The monthly average magnetic flux of the quiet regions is 1.12 times that of active regions in the cycle. (2) The ratio of quiet region flux to that of the total Sun equally characterizes the course of a solar cycle. The 6-month running-average flux ratio of quiet region had been larger than 90.0% for 28 continuous months from July 2007 to October 2009, which characterizes very well the grand solar minima of Cycles 23-24. (3) From the small to large end of the flux spectrum, the variations of numbers and total flux of the network elements show no-correlation, anti-correlation, and correlation with sunspots, respectively. The anti-correlated elements, covering the flux of (2.9 - 32.0)$\times 10^{18}$ Mx, occupies 77.2% of total element number and 37.4% of quiet Sun flux. These results provide insight into reason for anti-correlated variations of small-scale magnetic activity during the solar cycle.

Clear sky global solar irradiance on tilt angles of photovoltaic module in Perlis, Northern Malaysia

Abstract: The performance of a photovoltaic (PV) is highly influenced by its orientation and its tilt angle with the horizontal, due to the fact that both the orientation and tilt angle change the amount of solar radiation reaching the surface of the PV module. This paper presents a calculation of tilt angle and global solar irradiance on PV module in Perlis, Northern Malaysia. A mathematic method is used to calculate tilt angles and clear sky global solar irradiance, which depend on latitude and day number. The clear sky global solar irradiance consists of beam, diffuse and reflected solar irradiance. The tilt angles and clear sky global solar irradiance change every day in a year and analyzed. The monthly average beam, diffuse, reflected and clear sky global solar irradiance are shown and analyzed in this paper. The tilt angles of PV module in Perlis, Northern Malaysia are −17.16° to 29.74°. The positive, zero and negative tilt angles indicate that the PV module is facing south, on horizontal surface and north, respectively. The monthly average beam solar irradiance give a highest value compared with the diffuse and reflected solar irradiance. The average monthly beam solar irradiance of a year is, 968.36 W/m2, diffuse and reflected solar irradiance are 88.22 W/m2, and 4.70 W/m2, respectively. Based on global solar irradiance of a year, Perlis has a big global solar irradiance potential, its average is 1019 W/m2. These data show that the clear sky global solar irradiance can be used for certain application, especially in PV power generation.

Prediction of optimum angle of inclination for flat plate solar collector in Zaria, Nigeria.

Abstract: A flat plate surface solar collector of dimension 0.5 m 2 , hinged on a horizontal support for quick adjustment of inclination from 0 to 90 o was fabricated, marked out at 1 o intervals on a telescopic leg graduated in degrees. Measurement of the solar radiation, varying degrees of inclination were taken between 12:00 noon and 2:30 pm for 4 days at clear sky hours, within the week of n th day of the year. The measurements were made for each month of the year in Zaria, Kaduna State, Nigeria. At each degree of inclination, the solar radiation intensity was replicated three times and the average value was taken. The flat plate was set truly facing south with an engineering prismatic compass. The result showed that the optimum angle of inclination of a flat plate for maximum collection of solar radiation intensities are 26.5, 24.5, 10.0, 19.5, 26.0, 30.0, 24.0, 21.0, 11.5, 19.5, 27.0 and 30.0 o , in the months of January to December, respectively. This work also revealed that the average angle of inclination at which a flat surface solar collector will be mounted at fixed position in Zaria is 22.5 o . The analysis indicated that when a flat surface was located at the predicted optimum angle of inclination for each month of the year, an average annual increment of 4.23 % solar radiation intensity was achieved, when compared with the yearly average solar radiation intensity harnessed by the same flat plate collector on horizontal position, and under the same condition. This percentage increase amounted to annual average solar energy gain of 370,670 MJ/m 2 , at no extra-cost, other than positioning the solar collector at the identified optimum angle of inclination. Comparison of the measured and calculated optimum values of angle of inclination of a flat plate surface for trapping maximum solar radiation intensity for each month of the year indicated a high correlation with R 2 of 0.97.

Ceramic Based Intelligent Piezoelectric Energy Harvesting Device

Abstract: In 2008, total worldwide energy consumption was 474 exajoules (474×1018 J) with 80 to 90 percent derived from fossil fuels(1). This is equivalent to an average power consumption rate of 15 terawatts (1.504×1013 W). Most of the world's energy resources are from the sun's rays hitting Earth. Some of that energy has been preserved as fossil energy; some are directly or indirectly usable, for example via wind, hydroor wave power. The term solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just visible light. The estimates of remaining non-renewable worldwide energy resources vary, with the remaining fossil fuels totalling an estimated 0.4YJ (1YJ = 1024J) and the available nuclear fuel such as uranium exceeding 2.5YJ. Fossil fuels range from 0.6-3YJ if estimates of reserves of methane are accurate and become technically extractable. The twentieth century saw a rapid twenty-fold increase in the use of fossil fuels. Between 1980 and 2006, the worldwide annual growth rate was 2%(1). According to the US Energy Information Administration's 2006, the estimated 471.8EJ total consumption in 2004 was divided as follows, with fossil fuels supplying 86% of the world's energy, see Figure 1. Coal fuelled the industrial revolution in the 18th and 19th century. With the advent of the automobile, airplanes and the spreading use of electricity, oil became the dominant fuel during the twentieth century. The growth of oil as the largest fossil fuel was further enabled by steadily dropping prices from 1920 until 1973.

Role of the ocean in controlling atmospheric CO 2 concentration in the course of global glaciations

Abstract: Responses of ocean circulation and ocean carbon cycle in the course of a global glaciation from the present Earth conditions are investigated by using a coupled climate-biogeochemical model. We investigate steady states of the climate system under colder conditions induced by a reduction of solar constant from the present condition. A globally ice-covered solution is obtained under the solar constant of 92.2% of the present value. We found that because almost all of sea water reaches the frozen point, the ocean stratification is maintained not by temperature but by salinity just before the global glaciation (at the solar constant of 92.3%). It is demonstrated that the ocean circulation is driven not by the surface cooling but by the surface freshwater forcing associated with formation and melting of sea ice. As a result, the deep ocean is ventilated exclusively by deep water formation in southern high latitudes where sea ice production takes place much more massively than northern high latitudes. We also found that atmospheric CO2 concentration decreases through the ocean carbon cycle. This reduction is explained primarily by an increase of solubility of CO2 due to a decrease of sea surface temperature, whereas the export production weakens by 30% just before the global glaciation. In order to investigate the conditions for the atmospheric CO2 reduction to cause global glaciations, we also conduct a series of simulations in which the total amount of carbon in the atmosphere–ocean system is reduced from the present condition. Under the present solar constant, the results show that the global glaciation takes place when the total carbon decreases to be 70% of the present-day value. Just before the glaciation, weathering rate becomes very small (almost 10% of the present value) and the organic carbon burial declines due to weakened biological productivity. Therefore, outgoing carbon flux from the atmosphere–ocean system significantly decreases. This suggests the atmosphere–ocean system has strong negative feedback loops against decline of the total carbon content. The results obtained here imply that some processes outside the atmosphere–ocean feedback loops may be required to cause global glaciations.

The Smithsonian solar constant data revisited: no evidence for a strong effect of solar activity in ground-based insolation data

Abstract: . Apparent evidence for a strong signature of solar activity in ground-based insolation data was recently reported. In particular, a strong increase of the irradiance of the direct solar beam with sunspot number as well as a decline of the brightness of the solar aureole and the measured precipitable water content of the atmosphere with solar activity were presented. The latter effect was interpreted as evidence for cosmic-ray-induced aerosol formation. Here I show that these spurious results are due to a failure to correct for seasonal variations and the effects of volcanic eruptions and local pollution in the data. After correcting for these biases, neither the atmospheric water content nor the brightness of the solar aureole show any significant change with solar activity, and the variations of the solar-beam irradiance with sunspot number are in agreement with previous estimates. Hence there is no evidence for the influence of solar activity on the climate being stronger than currently thought.

Spectral solar irradiance and its entropic effect on earth's climate

Abstract: . The high-resolution measurements of the spectral solar irradiance at the top of the Earth's atmosphere by the Solar Radiation and Climate Experiment (SORCE) satellite suggest significant deviation of solar radiation from the commonly assumed blackbody radiation. Here, we use these spectral irradiance measurements to estimate the Earth's incident solar radiation entropy flux, and examine the importance of a proper estimation approach. The Earth's incident solar radiation entropy flux estimated by directly applying the observed spectral solar irradiance into the most accurate Planck expression is compared with that estimated with a conventional approach that uses the Sun's brightness temperature under the assumption of a blackbody Sun. The globally averaged non-blackbody incident solar radiation entropy flux at the top of the Earth's atmosphere equals 0.31 W m−2 K−1. This value is about 4 times larger than that estimated from the conventional blackbody approach, with the difference comparable to the typical value of the entropy production rate associated with atmospheric latent heat process. Further analysis reveals that the decrease of spectral solar radiation entropy flux with radiation traveling distance, unlike the decrease of spectral solar radiation energy flux with radiation traveling distance, is wavelength dependent, and that the difference between the two estimates can be attributed to the fact that the conventional approach ignores the influence of radiation traveling distance on the spectral solar radiation entropy flux. Moreover, sensitivity study further shows that the distribution of top-of-atmosphere spectral solar irradiance could significantly impact the magnitude of the estimated Earth's incident solar radiation entropy flux. These results together suggest that the spectral distribution of incident solar radiation is critical for determining the Earth's incident solar radiation entropy flux, and thus the Earth's climate.

Solar spectral irradiance variability from SCIAMACHY on daily to several decades timescales

Abstract: The sun's radiative output is the primary energy input to the Earth, planets, and the entire heliosphere. It determines the thermal structure of the Earth s atmosphere, and overall it sustains life as we know it. The solar spectral irradiance (SSI) determines the general circulation, ozone photochemistry, and weather-climate system. Both SSI and the total solar irradiance (TSI or 'solar constant') vary in time. The 'solar constant' is obtained by integrating SSI over the entire electromagnetic spectrum. It is now established to vary about 0.2 0.4% during the 27-day solar rotation due to transit of active region across the solar disk and 0.1% over an 11-year solar cycle due to variations of magnetic surface activity of the sun related to the reversal of the solar magnetic field. While SSI variability in the UV is moderately well understood, little is known about variability in the optical and near IR (vis-IR) spectral range. This is because while the variations in UV are large, vis-IR variations are small, which are within the noise level of the instrument. The overall goal of this dissertation, therefore, is to improve our understanding of SSI variability especially at longer wavelengths beyond the UV. Regular monitoring of SSI from space covering the entire UV and vis-IR has become available at a moderately high spectral resolution with SCIAMACHY aboard ENVISAT since 2002. This cumulative dissertation presents in three published manuscripts the most recent progress in understanding SSI variability not only in the UV but also in the vis-IR spectral region using SCIAMACHY data. The first published manuscript ad- dresses the validation of radiometrically calibrated SSI from SCIAMACHY to existing SSI data (from ground and space) and to compare SCIAMACHY SSI variations with various other satellite data from SIM onboard SORCE, SUSIM onboard UARS, and SBUVs. The second published manuscript describes the parametrization of SCIAMACHY SSI time series in terms of solar proxies: Mg II core-to-wing (ctw) ratio for faculae brightening and photometric sunspot index (PSI) for sunspot darkening. This simple irradiance model is referred to as the SCIA proxy model. This model allows us to estimate past solar irradiance variations over several decades well beyond the observation period of the SCIAMACHY satellite. Most satellites observing in the optical spectral range suffer from hard radiation in space, particular in the UV, therefore these satellites optically degrade with time. The parametrization using the solar proxy model also enables the application of a simple degradation correction with the need for detailed re-calibration of solar irradiance measurements, which is not always possible or feasible. So far these two goals focus on short timescales (days to several months). The third published manuscript deals with the application of the model to reconstruct daily SSI variability from 1978 to present, covering several decades. The reconstructed SSI from SCIA proxy on daily to decadal timescales are compared to the solar…

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

Abstract: 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).

A solar cell design for the Bepi Colombo high intensity — High temperature mission

Abstract: An extensive set of environmental tests revealed that the standard solar cell design incorporated in the typical photovoltaic array configuration performs less than expected in the high intensity high temperature environment (HIHT) of the Bepi Colombo mission, characterized by temperatures between 200 and 230 °C and an incident irradiance of up to 11 times the air mass zero spectrum. Fill factor driven performance degradations of up to 20 % were observed. With the help of electroluminescence imaging and a set of root cause tests with limited material combinations, the degradation mechanism was identified. A new cell design was developed based on these results and verified in a 1500 actual test hour UV test. Despite a cell temperature of 230 °C and 11 solar constant irradiance, the cell performance remained unaffected. This shows the general suitability of this design for HIHT missions.

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

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

A new solution method for black-body radiation inversion and the solar area-temperature distribution

Abstract: The effective temperature of the solar photosphere is usually obtained according to the solar constant, based on the Stefan-Boltzmann law. However its temperature distribution is not homogeneous. A hopeful way to obtain the area-temperature distribution of the solar photosphere is to solve the Black-body Radiation Inversion (BRI) problem. In this paper, a new practical solution method for BRI is developed. The theoretical analysis and numerical calculations show the low-temperature distribution difficulty of BRI is solved by this new method. Then the area-temperature distribution of the solar photosphere is obtained, according to the measured absolute solar spectral irradiance. It is the first realization of BRI for a real system after almost three decades of efforts. The results are comparable to that from the Stefan-Boltzmann law.

The Smithsonian solar constant data revisited: no evidence for cosmic-ray induced aerosol formation in terrestrial insolation data

Abstract: This paper is effectively a technical comment on the paper by Weber in Ann Phys (Berlin). For a long time scientific practice has generally been to publish comments in the same journal as the original paper, to allow comments and corrections (and the courtesy of a reply from the author) to be associated with the first piece of work. Nowadays web linking improves this so readers of a paper cannot be unaware of comments and corrections when C984

Accumulation of Solar Irradiance Anomaly as a Mechanism for Global Temperature Dynamics

Abstract: Global temperature (GT) changes over the 20th century and glacial-interglacial periods are commonly thought to be dominated by feedbacks, with relatively small direct effects from variation of solar insolation. Here is presented a novel empirical and physically-based auto-regressive AR(1) model, where temperature response is the integral of the magnitude of solar forcing over its duration, and amplification increases with depth in the atmospheric/ocean system. The model explains 76% of the variation in GT from the 1950s by solar heating at a rate of $0.06\pm 0.03K W^{-1}m^{-2}Yr^{-1}$ relative to the solar constant of $1366Wm^{-2}$. Miss-specification of long-equilibrium dynamics by empirical fitting methods (as shown by poor performance on simulated time series) and atmospheric forcing assumptions have likely resulted in underestimation of solar influence. The solar accumulation model is proposed as a credible mechanism for explaining both paleoclimatic temperature variability and present-day warming through high sensitivity to solar irradiance anomaly.

Effects of the long -term variations of the solar wind on the near-earth space

Abstract: There are a lot of the data of the solar wind parameters accumulated during epoch of the satellite exploration of the Space. It is possible to study interconnection between the long - term variations of the parameters of the solar wind and of the near - Earth Space during the last 4 cycles of the solar activity. We analyze quasi - stationary variations of the solar wind parameters during the solar cycle 23 in comparison with the correspondent changes in the cycles 20, 21 and 22. It was found that the main peculiarities of the cycle 23 are unusually low values of the solar wind magnetic field. We suggest that such long - term variations of the solar activity could change geoefficiency of the solar wind parameters which is expressed as diminishing of the electromagnetic energy transferred into the near - Earth Space. Therefore the global electric circuit parameters are changing correspondingly producing significant variations in the Earth ionosphere and atmosphere and indirectly in the planet climate. The latest experimentally observed low values of the ground surface electric field, low concentration of the charged particles in the ionosphere, increasing area of the ice cover in the Arctic could be attributed to these changes in the solar wind parameters. 2. Experimental data In this paper we used data of the solar activity and the parameters of the solar wind accumulated in the epoch of satellite explorations. As a level of the solar activity the number of Sun spots (W) was used. Results of analysis of the long - term variations of full vector of the magnetic field of the solar wind will be presented here. Period of observation is 42 years (from 1965 till 2010). The data were taken from INTERNET OMNI system. The hourly values of different parameters of the solar wind were used as original material. Afterwards the averaged monthly and annual values were calculated from it. The long - term variations (1965 - 2007 years) of such parameters of the solar wind as its density and velocity, three components and full vector of interplanetary magnetic field (IMF) were studied. In this paper we used data of the hourly values of ionospheric parameters of the station Sodankyla, Finland (Ф' = 64.0°) from 1965 till 2007 years. Results of comparison of the solar activity and the values of the IMF full vector with parameters of the ionosphere are presented below. 3. Results of experimental data analysis Existence of long term experimental data of ionosphere were using for study of connection f0 F2 и hmax F2 with solar activity expressed by Sun spot number and full vector of the magnetic field of the solar wind which is connected with large magnetic fields of the Sun. Mean annual values of number of Sun spot (W), full vector of IMF (Bsw), critical frequency (hmax F2) and of altitude of maximum of F2 layer (hmax F2) are presented on Figure 1. Similarity of long -term variations of the Sun spot number and the f 0 F2 shows that EUV radiation is the main source of energy of ionization of atmosphere. The value of the coefficient correlation between these two parameters is very high and equal 0.95 with high level of statistical confidence. Asymmetry of cyclic solar activity is clearer in variations of the values of full vector IMF, rather than in W dynamics.

Picard satellite for solar astrometry

Abstract: The Picard solar satellite has been launched on June 15, 2010. This mission is dedicated to the measurement of the solar diameter with an expected accuracy of milliarcseconds of arc. The radiometer onboard is to measure the total solar irradiance. The final goal is the evaluation of the W, the logarithmic ratio of radius and luminosity. This parameter will help the climatologists to recover past values of the solar luminosity when the radius is available from ancient eclipses data.