Showing papers on "Solar constant published in 1988"
TL;DR: In this article, the authors used the solar distortion telescope to measure the limb shape and latitude dependence of the limb brightness during the summer months for a 5-year period -a time base sufficient to detect solar cycle trends in the data.
Abstract: The solar distortion telescope has been used to measure the limb shape and latitude
dependence of the limb brightness during the summer months for a 5-year period - a time base sufficient to detect solar cycle trends in the data. Comparison of these
observations with spaceborne measurements of the solar constant suggests that a
significant part of the solar cycle variation in irradiance is a result of temporal changes
in the latitude-dependent surface temperature of the sun.
165 citations
01 Jan 1988
TL;DR: The Earth Radiation Budget Experiment (ERBE) data studied at present are as follows: (1) solar data from ERBS, NOAA-9, and NOAA-10 as discussed by the authors, which serve as a calibration check on the earth viewing radiometers, as well as provide the experimental value of the solar constant needed in net radiation computations.
Abstract: The Earth Radiation Budget Experiment (ERBE) data studied at present are as follows: (1) Solar Data from ERBS, NOAA-9, and NOAA-10. The solar total irradiance data obtained by the ERBE solar monitors serve as a calibration check on the earth viewing radiometers, as well as provide the experimental value of the solar constant needed in the net radiation computations. (2) The collocated satellite altitude irradiances from ERBS and Nimbus-7 Earth Radiation Budget Measurements are investigated. The sun-synchronous, near-local-noon Nimbus-7 satellite has coincident orbital intersections with the non-sun-synchronous ERBS spacecraft. The objective here is to compare the WFOV and MFOV (wide and medium field-of-view) observations of the ERBS/ERBE, and the Nimbus-7 ERB data sets at the points of their orbital intersections. (3) Globally and zonally averaged ERBE/ERBS data are examined. Investigations of the globally and zonally averaged ERB obtained from the ERBS SCANNER, MFOV and WFOV and the Nimbus-7 WFOV is being carried out to assess the sensor performance.
154 citations
TL;DR: In this article, the effects of solar variations on the earth climate and the implications of the observations for theoretical models of convective-envelope processes (thermal diffusion near the surface and magnetic pressure in the interior) are discussed.
Abstract: Data on solar luminosity variations are compiled in graphs and analyzed, with a focus on the SMM satellite bolometric measurements and other observations made since 1983. Consideration is given to total irradiance measurements in integrated light; emission-line variability in the visible, UV, and IR; mechanisms contributing to the solar variability (sunspots, faculae, rotation, oscillations, granulation, and active networks); the role of the solar magnetic cycle; and other observable parameters indicating variability. Also discussed are the effects of solar variations on the earth climate and the implications of the observations for theoretical models of convective-envelope processes (thermal diffusion near the surface and magnetic pressure in the interior).
83 citations
TL;DR: In this paper, the authors describe the nine-year Nimbus-7 total solar irradiance data set and compare it with similar data sets from the solar maximum mission (SMM) and other satellite solar monitoring programs.
Abstract: The advent of reliable extraterrestrial solar irradiance measurements from satellites has supplied the impetus for new research in solar physics and solar-terrestrial relationships. The records for the principal experiments now extend beyond nine years. The Nimbus-7 measurements began in November 1978 and the Solar Maximum Mission (SMM) results started in February 1980. Both the ERB experiment of Nimbus-7 and the ACRIM experiment of SMM are still operational as of this writing (June 1988). We describe the nine-year Nimbus-7 total solar irradiance data set and compare it with similar data sets from the SMM and other satellite solar monitoring programs. Long-term downward trends of less than 0.02 % per year had been noted during the decaying portion of solar cycle 21 with indications that a leveling off and possible reversal of the trend was being experienced as we enter the new cycle. It had been demonstrated that fluctuations in the data over shorter periods corresponded to solar activity, from a primary discovery of irradiance depletions in times of building large sunspot groups to more subtle effects on the scale of solar rotation. Studies of the frequency spectra of the measurements have advanced the interest in helioseismology or mode analysis. Studies of photospheric activity have advanced by modelling of the sunspot blocking and photospheric brightening versus the measured irradiance. The theories are being extended to longer time-scales which indicate that solar irradiance is higher near solar cycle maximum, as defined by activity, and somewhat lower during the period between cycles. While measurements of total solar irradiance, the solar constant, alone cannot be employed to answer all of the questions of solar physics or helioclimatology, these long-term, high-precision data sets are valuable to both disciplines. The continuation of such measurements to more meaningful, longer time-scales should have a high priority in the international space community.
82 citations
TL;DR: The performance of the Eppley pyrgeometer with a silicon dome presents several anomalies during daytime measurements as mentioned in this paper, which are related mainly to the solar heating of the dome, which causes nearly instantaneous fluctuations, about ± 1% to 2% from the average value, in the longwave irradiance measured by the pyrges during cloudless days.
Abstract: The performance of the Eppley pyrgeometer with a silicon dome presents several anomalies during daytime measurements. These problems are related mainly to the solar heating of the dome, which causes nearly instantaneous fluctuations, about ±1%–2% from the average value, in the longwave irradiance measured by the pyrgeometer during cloudless days. An evaluation of the solar heating effect of the dome made with a set of sun and shade experiments indicates that the pyrgeometer output includes an equivalent of about 3.6% of the incoming solar radiation. In spite of the improvement with the use of silicon instead of KRS-5 domes, the error due to solar heating requires some kind of correction. Sun and shade experiments under a number of wind speed conditions are used to derive an empirical correction that is based on the global solar radiation.
54 citations
TL;DR: Comparisons with ground-based, irradiance spectrophotometry of selected Fraunhofer lines independently confirm the variability in the ACRIM Se, signal, indicate that the source of irradiance is faculae, and indicate that ACRim Se, follows the 11-year activity cycle.
Abstract: Active Cavity Radiometer Irradiance Monitor (ACRIM) solar constant measurements from 1980 to 1986 are compared with ground-based, irradiance spectrophotometry of selected Fraunhofer lines. Both data sets were identically sampled and smoothed with an 85-day running mean, and the ACRIM total solar irradiance ( S ) values were corrected for sunspot blocking ( S c ). The strength of the mid-photospheric manganese 539.4-nanometer line tracks almost perfectly with ACRIM S e , Other spectral features formed high in the photosphere and chromosphere also track well. These comparisons independently confirm the variability in the ACRIM S e , signal, indicate that the source of irradiance is faculae, and indicate that ACRIM S e , follows the 11-year activity cycle.
50 citations
TL;DR: In this paper, contrast models for solar active region and global photospheric features are used to reproduce the observed Active Cavity Radiometer and Earth Radiation Budget secular trends in reasonably good fashion.
Abstract: In this paper, contrast models for solar active region and global photospheric features are used to reproduce the observed Active Cavity Radiometer and Earth Radiation Budget secular trends in reasonably good fashion. A prediction for the next decade of solar constant variations is made using the model. Secular trends in the solar constant obtained from the present model support the view that the Maunder Minimum may be related to the Little Ice Age of the 17th century.
50 citations
TL;DR: The efficiency with which the two-stage solar concentrator concentrated 55 W of sunlight to a small spot suggests that the system would be an excellent candidate for solar pumping of solid state lasers.
Abstract: Measurements are reported of the irradiance produced by a two-stage solar concentrator designed to approach the thermodynamic limit. Sunlight is collected by a 40.6-cm diam parabolic primary which forms a 0.98-cm diam image. The image is reconcentrated by a nonimaging refracting secondary with index n = 1.53 to a final aperture 1.27 mm in diameter. Thus the geometrical concentration ratio is 102, 000. The highest irradiance value achieved was 4.4 +/- 0.2 kW cm(-2), or 56,000 +/- 5000 suns, relative to a solar disk insolation of 800 W m(-2). This is greater than the previous peak solar irradiance record by nearly a factor of 3, and it is 68% of that existing at the solar surface itself. The efficiency with which we concentrated 55 W of sunlight to a small spot suggests that our two-stage system would be an excellent candidate for solar pumping of solid state lasers.
37 citations
TL;DR: In this article, the solar EUV irradiance data base acquired over the past 25 years is briefly described, and the extent to which emissions at different EUV wavelengths and ground-based solar indices are similar, is examined statistically over time scales of the 27-day solar rotation, and less rigorously over the eleven year solar cycle.
27 citations
TL;DR: In this paper, the authors compare the solar irradiance data obtained by the NOAA 9 and 10 spacecraft with those obtained by NASA's Active Cavity Irradiance Monitor 1, as well as sounding rockets and the Nimbus 7 Earth Radiation Budget channel 10C.
Abstract: Earth Radiation Budget Experiment solar total irradiance data obtained by the solar monitors of the NOAA 9 and 10 spacecraft are presently compared with those obtained by the Solar Maximum Mission's Active Cavity Irradiance Monitor 1, as well as sounding rockets and the Nimbus 7 Earth Radiation Budget channel 10C. A disparity is noted among total irradiance values obtained in near-simultaneous measurements with absolute pyrheliometers of similar design and operational modes which (1) indicates the uncertainty associated with currently available instruments, and (2) recommends intercalibration of electrically self-calibrating pyrheliometers from spacecraft.
23 citations
TL;DR: A recent article by Schotland and Lea discusses the errors in radiometer calibration by the Langley method and the detail required for very precise work, and by using multiple-pass Langley analyses the errors due to air mass assignments can be reduced significantly.
Abstract: A recent article by Schotland and Lea [
Appl Opt25,
2486 (
1986)] discusses the errors in radiometer calibration by the Langley method and the detail required for very precise work Their numerical methods on aerosol air mass can be simplified for use in the calibration of the worldwide sunphotometer network by using geometric considerations, assuming aerosol scale heights of ~1 Km and using the apparent solar zenith angle at the instrument as the independent variable in these formulas, so that refraction effects are incorporated By using multiple-pass Langley analyses the errors due to air mass assignments can be reduced significantly
TL;DR: In this article, two Kipp and Zonen solarimeters, one of which incorporated a shadow ring, were used for the measurement of the global and diffuse components of solar radiation for Kano.
TL;DR: In this paper, the authors show that bright, contiguous active regions cause much of the observed variability in the full disc UV irradiances over time scales of solar rotation and active region evolution, but can account for only about half variability observed over the 11-year solar cycle.
TL;DR: From June 1986 through Nov 1987, the Earth Radiation Budget Satellite (ERBS) pyrheliometric measurements indicated that the solar constant was increasing approximately +0.02 percent per year.
TL;DR: In this paper, a study of the solar total irradiance data of the Active Cavity Radiometer Irradiance Monitor on the SMM satellite shows a small but formally significant shift in the frequencies of solar acoustic (p-mode) oscillations between the epochs of maximum and minimum solar activity.
Abstract: A study of the solar total irradiance data of the Active Cavity Radiometer Irradiance Monitor on the SMM satellite shows a small but formally significant shift in the frequencies of solar acoustic (p-mode) oscillations between the epochs of maximum and minimum solar activity. Specifically, the mean frequency of the strongest p-mode resonances of low spherical-harmonic degree (l = 0-2) is approximately 1.3 parts in 10,000 higher in 1980, near the time of sunspot maximum, than at around 1985, near sunspot minimum. The observed frequency shift may be an 11-yr effect but the precise mechanism is not clear.
TL;DR: The cavity pyrheliometer sensor aboard Nimbus 7 is now in its tenth year of operation and results for 9 1/2 years show a decreasing trend through the end of solar cycle 21 of approximately -0.015 percent per year, a leveling off near solar minimum and an increasing irradiance for the beginning of cycle 22.
TL;DR: The difficulty in correlating models of solar irradiance variations from ground-based observations with spacecraft data is examined in this paper, where a photometric program is described which produces sunspot irradiance fluctuation information that is repeatable to within 10 millionths of the mean irradiance.
01 Jan 1988
TL;DR: In this paper, the power spectra of the time series of 270 days in 1980 and of 240 days in 1984 are analyzed using a statistical method for the determination of the basic g-mode period separation To and the rotational frequency v R.
Abstract: Solar irradiance data from the AC RIM solar constant experiment on board the Solar Maximum Mission satellite (SMM) have been used to search for solar gravity modes. The power spectra of the time series of 270 days in 1980 and of 240 days in 1984 are analysed using a statistical method for the determination of the basic g-mode period separation To and the rotational frequency v R. In the view of the proposal of weakly interacting massive particles (WIMP) in the solar core and their impact on T0 the search has been extended down to 25 minutes. The results of the analysis of both time series in the frequency range from 10 to 40 μHz are best fitted by a T0 of 29.85 minutes. This is close to the expected value for the WIMP model. The angular velocity in the center of the Sun inferred from the rotational splitting of the g-modes amounts to 6.6•10-6 per sec, which is 2.3 times the photospheric rate.
TL;DR: The corrected values for Table 1 are, for Channel 1: Equivalent Solar Radiance = 499., a =.528, 13 = - 17.6, and for Channel 2: ESRR = 323, a=.342, /3 = - 11.2 as discussed by the authors.
TL;DR: In this paper, the authors show that most of the total solar irradiance variability is explained by the effect of active and passive sunspots and bright magnetic elements, and demonstrate the limitation of simple analyses, as linear regression or even bivariate analysis which can reveal only the most obvious correlations between the used data sets.
01 Nov 1988
TL;DR: In this paper, seven years and five months of Nimbus-7 Earth Radiation Budget (ERB) solar data are available on a single ERB solar analysis tape (ESAT) for the period covered is November 16, 1978 through March 31, 1986.
Abstract: Seven years and five months of Nimbus-7 Earth Radiation Budget (ERB) solar data are available on a single ERB Solar Analysis Tape (ESAT) The period covered is November 16, 1978 through March 31, 1986 The Nimbus-7 satellite performs approximately 14 orbits per day and the ERB solar telescope observes the sun once per orbit as the satellite crosses the southern terminator The solar data were carefully calibrated and screened Orbital and daily mean values are given for the total solar irradiance plus other spectral intervals (10 solar channels in all) In addition, selected solar activity indicators are included on the ESAT The ESAT User's Guide is an update of the previous ESAT User's Guide (NASA TM 86143) and includes more detailed information on the solar data calibration, screening procedures, updated solar data plots, and applications to solar variability Details of the tape format, including source code to access ESAT, are included
TL;DR: AESSIM as discussed by the authors, the Absolute, Extreme-Ultraviolet, Solar Spectral Irradiance Monitor, is designed to measure the absolute Solar spectral irradiance at extreme-ultraviolet (EUV) wavelengths.
TL;DR: Based on dynamical energy transport and thermodynamic energy balance in the earth's atmosphere-ocean system, a steady two-dimensional climate model with residual circulation is proposed in this paper, which includes some important physical processes with feedbacks such as ice caps-albedo, water vapor-temperature, etc.
Abstract: Based on dynamical energy transport and thermodynamic energy balance in the earth’s atmosphere-ocean system a steady two-dimensional climate model with residual circulation is proposed. In the model, we include some important physical processes with feedbacks such as ice caps-albedo, water vapor-temperature, etc. The simulated steady tempsrature field is very close to that of the real atmosphere. The numerical experiments show that doubling of the atmospheric carbon dioxide results in temperature increase of 1~2°C at the low latitude surface and 6~8°C at the high latitude surface. It is shown that a6% decrease in the solar constant is required for the — 10°C ice edge to move from its present latitude ~70° to~50°.
TL;DR: In this paper, the authors studied the association between different aspects of the magnetic field behavior in large active regions and the solar irradiance variations, and found that irradiance decreases were accompanied by enhanced flare and coronal mass ejection activity.
TL;DR: In this paper, the authors analyzed the radiometric record of the total solar irradiance obtained over the past ten years and revealed characteristic variations caused by sunspots and faculae, the magnetic network, and also the sun's internal oscillations and photospheric convection.
TL;DR: However, the spectrum persistently published by Langley in the scientific literature and reproduced since, is still worse in this respect owing to an error in the material first given to the engraver.