Showing papers on "Solar constant published in 1992"
TL;DR: In this article, a correlation between measured total solar irradiance (corrected for sunspot effects) and a Ca II surrogate for bright magnetic features was found, and it was estimated that the Sun's radiative output in the absence of such features to be 1365.43 w/m2, or 0.24% below its mean value for the 1980 to 1986 period.
Abstract: The coincidence between the Maunder Minimum of solar magnetic activity from 1645 to 1715 and the coldest temperatures of the Little Ice Age raises the question of possible solar forcing of the Earth's climate. Using a correlation which we find between measured total solar irradiance (corrected for sunspot effects) and a Ca II surrogate for bright magnetic features, we estimate the Sun's radiative output in the absence of such features to be 1365.43 w/m2, or 0.15% below its mean value of 1367.54 W/m2 measured during the period 1980 to 1986 by the ACRIM experiment. Observations of extant solar-type stars suggest that the Ca II surrogate vas darker during the Maunder Minimum. Allowing for this, we estimate the total solar irradiance to be 1364.28 W/m2 or 0.24% below its mean value for the 1980 to 1986 period. The decrease in the global equilibrium temperature of the Earth due to a decrease of 0.24% in total solar irradiance lies in the range from 0.2° C to 0.6° C, which can be compared with the approximately 1° C cooling experienced during the Little Ice Age, relative to the present.
185 citations
TL;DR: In this paper, an analytical solution for the effective albedo, the effective emissivity, and the radiative equilibrium temperature in the shadowed portions of a spherical bowl-shaped crater is presented.
150 citations
01 Jan 1992
TL;DR: The oceans have a major influence on the climate of the earth through effects on the global solar radiation budget, on meridional heat transport, and on the trace gas composition of the atmosphere as discussed by the authors.
Abstract: The oceans have a major influence on the climate of the earth through effects on the global solar radiation budget, on meridional heat transport, and on the trace gas composition of the atmosphere. The climate of the ocean-atmosphere system is sensitive to variations of the solar constant and the orbital characteristics of the earth. However, the properties of surface ocean waters and of the marine atmosphere are modified also by the optical and biochemical properties of marine organisms, in particular, the phytoplankton. It is generally recognized that the global climate would have been quite different through geological time in the absence of life in the sea.
52 citations
TL;DR: By imaging sunlight diffracted by 20-and 30-micron diameter pinholes onto the entrance aperture of a photoelectric grating scanner, the solar spectral irradiance was determined relative to the spectrophotometric standard star Vega, observed at night with the same instrument as mentioned in this paper.
Abstract: By imaging sunlight diffracted by 20- and 30-micron diameter pinholes onto the entrance aperture of a photoelectric grating scanner, the solar spectral irradiance was determined relative to the spectrophotometric standard star Vega, observed at night with the same instrument. Solar irradiances are tabulated at 4 A increments from 3295 A to 8500 A. Over most of the visible spectrum, the internal error of measurement is less than 2 percent. This calibration is compared with earlier irradiance measurements by Neckel and Labs (1984) and by Arvesen et al. (1969) and with the high-resolution solar atlas by Kurucz et al. The three calibrations agree well in visible light but differ by as much as 10 percent in the ultraviolet.
37 citations
TL;DR: In this article, global relationships among the earth's radiation budget, cloudiness, solar constant, volcanic aerosols, and surface temperature were analyzed using data obtained by the Nimbus-7 spacecraft.
Abstract: Global relationships among the earth's radiation budget, cloudiness, solar constant, volcanic aerosols, and surface temperature are analyzed using data obtained by the Nimbus-7 spacecraft. It was found that these parameters were interrelated on interannual time scales, demonstrating that the interannual variability in the earth's climate (i.e., radiation budget) is detectable and observable by current spaceborne instruments. The degree of global interannual variation is on the order of tenths of percent.
30 citations
TL;DR: In this paper, the authors examined the effect of external forcing on large-scale surface temperature by analyzing several long runs of the Community Climate Model (CCMO) with idealized boundary conditions and forcing.
Abstract: The concept of “forced” and “free” variations of large-scale surface temperature is examined by analyzing several long runs of the Community Climate Model (CCMO) with idealized boundary conditions and forcing. 1) The planet is all land with uniform sea-level topography and fixed soil moisture. 2) The planetary surface and prescribed ozone are reflection symmetric across the equator and there is no generation of snow. 3) The obliquity is set to zero so that the climate is for a perpetual equinox solar insolation (i.e., sun fixed over the equator). After examining some relevant aspects of the undisturbed climate (surface temperature field) such as temporal and spatial autocorrelations and the corresponding spectra, two types of changes in external forcing are imposed to study the model response: 1) sinusoidal changes of the solar constant (5%, 10%, 90%, and 40% amplitudes) at periods of 15 and 30 days (the latter is the autocorrelation time for the global average surface temperature) and 20% at 60 ...
20 citations
TL;DR: In this paper, a seasonal one-and-a-half-dimensional (1 1 2 -D) energy-balance climate model including a detailed sea ice calculation and an interactive albedo formulation has been developed and is used to investigate the young sun climatic paradox.
19 citations
01 Dec 1992
TL;DR: For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of -8.019.
Abstract: For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.65 Wm(exp -2), a coefficient of variation (mean divided by the standard deviation) of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of -8.019 (inferring a highly significant non-random variation in the solar irradiance measurements, presumably related to the action of the solar cycle). Comparison of the 12-month moving average (also called the 13-month running mean) of solar irradiance to those of the usual descriptors of the solar cycle (i.e., sunspot number, 10.7-cm solar radio flux, and total corrected sunspot area) suggests possibly significant temporal differences. For example, solar irradiance is found to have been greatest on or before mid 1979 (leading solar maximum for cycle 21), lowest in early 1987 (lagging solar minimum for cycle 22), and was rising again through late 1990 (thus, lagging solar maximum for cycle 22), having last reported values below those that were seen in 1979 (even though cycles 21 and 22 were of comparable strength). Presuming a genuine correlation between solar irradiance and the solar cycle (in particular, sunspot number) one infers that the correlation is weak (having a coefficient of correlation r less than 0.84) and that major excursions (both as 'excesses' and 'deficits') have occurred (about every 2 to 3 years, perhaps suggesting a pulsating Sun).
5 citations
01 Aug 1992
4 citations
14 Nov 1992
TL;DR: In this article, a flat-field solar spectral irradiance monitor for in-orbit radiometric instrumentation recalibration has been proposed, which provides 0.1 to 0.2 nm resolution in the range 5-175 nm.
Abstract: : The goal of this research program was development of a method for obtaining daily radiometrically accurately, solar spectral irradiance data at EUV wavelengths. In orbit radiometric instrumentation recalibration is a fundamental requirement for accurate spectral flux measurements. We have studied a low-pressure version of the EUV radiance standard and concluded that a substantial redesign of it would be required if a suitable one is to be developed for in orbit calibration of a solar spectral irradiance monitor. We have reviewed the use, suitability, and the availability of thin film filters for in orbit EUV calibration. In our opinion, the availability of space qualified filters has not been verified. We have evaluated and chosen a design of a 4-spectrograph, flat-field package that provides 0.1 to 0.2 nm resolution in the range 5-175 nm with a total weight including detectors of 1.6 Kg. Several mission concepts, which involve rocket-borne, calibrated spectrometer underflights to recalibrate the Voyager spacecraft have been considered. Solar, Extreme-ultraviolet, Radiometric calibration.
2 citations
TL;DR: In this article, results of comparisons between Lowtran 6 and 7, the second including multiple scattering, are presented. And these simulations are also compared with measurements of global irradiance carried out with a radiometer UV, in the range (295÷385) nm.
Abstract: The Lowtran code is used to determine solar transmission, direct solar irradiance and total radiance. In this paper results of comparisons between Lowtran 6 and Lowtran 7, the second including multiple scattering, are presented. These simulations are also compared with measurements of global irradiance carried out with a radiometer UV, in the range (295÷385) nm.