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Showing papers on "Solar constant published in 1976"


Journal ArticleDOI
TL;DR: In this paper, the sensitivity of the earth's surface temperature to factors which can induce long-term climate change, such as a variation in solar constant, is estimated by employing two readily observable climate changes.
Abstract: The sensitivity of the earth's surface temperature to factors which can induce long-term climate change, such as a variation in solar constant, is estimated by employing two readily observable climate changes. One is the latitudinal change in annual mean climate, for which an interpretation of climatological data suggests that cloud amount is not a significant climate feedback mechanism, irrespective of how cloud amount might depend upon surface temperature, since there are compensating changes in both the solar and infrared optical properties of the atmosphere. It is further indicated that all other atmospheric feedback mechanisms, resulting, for example, from temperature-induced changes in water vapor amount, cloud altitude and lapse rate, collectively double the sensitivity of global surface temperature to a change in solar constant. The same conclusion is reached by considering a second type of climate change, that associated with seasonal variations for a given latitude zone. The seasonal in...

283 citations


Journal ArticleDOI
TL;DR: A simple mean hemispheric temperature model has been constructed in the form of a differential equation which is a function of three independent variables: carbon dioxide content of the air, volcanic ejecta and anthropogenic particulate pollution as mentioned in this paper.
Abstract: A simple mean hemispheric temperature model has been constructed in the form of a differential equation which is a function of three independent variables: carbon dioxide content of the air, volcanic ejecta and anthropogenic particulate pollution. This model appears to simulate the behavior of Northern Hemisphere mean temperatures as well as they are known and gives a different pattern of behavior for the Southern Hemisphere. By more completely accounting for those anthropogenic processes which produce both lower tropospheric aerosols and carbon dioxide, such as fossil fuel burning and agricultural burning, we calculate an expected slight decrease in surface temperature with an increase in CO2 content. Though an invariant “solar constant” was assumed, an unmistakable 20–25 year periodicity was found in the difference between the calculated and observed direct solar flux reaching the earth's surface, suggesting a definite but small periodic variation in the solar constant.

51 citations


Journal ArticleDOI
01 May 1976-Nature
TL;DR: In this article, the authors demonstrate that a much more modest ISM density of 102−103 cm−3 (a value typical of dense interstellar clouds in spiral arms) would prevent the solar wind from reaching the Earth, and propose that such a change in the Earth's space environment may trigger drastic climatic changes.
Abstract: SEVERAL authors1–3 have discussed whether past immersion of the Solar System in dense interstellar matter (ISM) might have left observable imprints on the Earth. Accretion cannot affect the solar constant significantly unless the surrounding ISM attains densities of 105–107 cm−3 (refs 2 and 3). We demonstrate here, however, that a much more modest ISM density of 102–103 cm−3 (a value typical of dense interstellar clouds in spiral arms) would prevent the solar wind from reaching the Earth, and propose that such a change in the Earth's space environment may trigger drastic climatic changes.

50 citations


Journal ArticleDOI
TL;DR: In this article, data from nine spacecraft are combined to study the properties of solar wind protons and the interplanetary magnetic field under unusual conditions that proton speed, density, and temperature variations are small over periods comparable to the solar wind expansion time.
Abstract: Data from nine spacecraft are combined to study the properties of solar wind protons and the interplanetary magnetic field under unusual conditions that proton speed, density, and temperature variations are small over periods comparable to the solar wind expansion time. From the 14 quiet intervals studied it is determined that (1) the square root of T versus velocity relation is less steep than was calculated from long-term-averaged or 3-hour quiet data; (2) the density varies approximately as the inverse square of the velocity; however, the data scatter is large, and an alternative interpretation is that mass flux is constant for velocities over about 400 km/s, in agreement with earlier studies; (3) the magnitude of the interplanetary magnetic field is independent of solar wind speed and density; and (4) the average field direction varies with the solar wind speed as predicted by Parker's spiral model. The intercalibration of solar wind measurements by different spacecraft is discussed in an appendix.

28 citations


Journal ArticleDOI
TL;DR: An overview of the solar monitoring program of NASA is presented, with special emphasis on the Solar Energy Monitor in Space (SEMIS) experiment, a combination of a solar constant detector and a prism monochromator which has been proposed for several of the spacecraft missions.
Abstract: The present status of our knowledge of the total and spectral irradiance of the sun is briefly reviewed. The currently accepted NASA/ASTM standard values of the solar constant and the extraterrestrial solar spectral irradiance are presented. The uncertainties in these values are relatively high. Data on the variability of the solar constant are conflicting and inconclusive. The variability of solar spectral irradiance. is almost totally unknown and unexplored. Some alleged sun-weather relationships are cited in support of the need of knowing more precisely the variations in total and spectral solar irradiance. An overview of the solar monitoring program of NASA is presented, with special emphasis on the Solar Energy Monitor in Space (SEMIS) experiment which has been proposed for several of the spacecraft missions. It is a combination of a solar constant detector and a prism monochromator.

27 citations


Journal ArticleDOI
TL;DR: In this article, the authors provided a set of tables listing the ratio of total daily solar energy received on a surface of given aspect and slope to that received on the horizontal surface at latitude 37° 30' S. By multiplying this figure by the total short wave radiation recorded on a horizontal plane subject to similar cloud and atmospheric conditions, daily or monthly values of solar radiation on a sloping surface may be estimated.
Abstract: An important parameter necessary for describing the microclimate or heat budget at the earth's surface is the quantity of incident solar radiation. However, measurements of radiation on other than a horizontal surface are not normally available. This article provides a set of tables listing the ratio of total daily solar energy received on a surface of given aspect and slope to that received on a horizontal surface at latitude 37° 30' S. By multiplying this figure by the total short wave radiation recorded on a horizontal plane subject to similar cloud and atmospheric conditions, daily or monthly values of solar radiation on a sloping surface may be approximated.

17 citations


Book ChapterDOI
01 Jan 1976
TL;DR: In this article, the authors consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone.
Abstract: Our understanding of the internal structure of the Sun and solar type stars has been undermined by recent observations. In this paper we consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone. The picture that emerges is one of confusion, and so it should be since we have no idea of what is going on inside the Sun and a fortiori of what is going on inside other stars.

12 citations


Journal ArticleDOI
TL;DR: In this paper, an analytical study is made of the number, stability and bifurcations of solutions of time-dependent Budyko-type climate models with various nonlinear albedo parameterizations.
Abstract: An analytical study is made of the number, stability and bifurcations of solutions of time-dependent Budyko-type climate models with various nonlinear albedo parameterizations. With Budyko's (1969) albedo, a general stability criterion is derived and it is found that, for the present value of the solar constant, the present climate and ice-covered earth solutions are stable, a spurious solution is unstable and there is an ice-free solution which is stable. A Seller's (1969) type albedo leads to a stable present climate and an ice-covered earth solution as well as an unstable climate. Faegre's (1972) albedo produces a present climate which is unstable and has an incorrect behavior as the solar constant or the infrared flux is changed, as well as a stable warmer climate and an ice-covered earth solution. It is found that latidutinal variations in the albedo way have a profound effect on the number and stability of the solutions.

12 citations


Journal ArticleDOI
TL;DR: Eddy et al. as discussed by the authors showed that for a 70-year period from A.D. 1645 to 1715 sunspots were almost totally absent on the surface of the sun, a true and strange anomaly.
Abstract: The history of science contains more than a few instances in which an old idea or hypothesis, considered improbable, dubious or merely wrong by modern investigators, is, through a combination of new evidence and a more thorough look at the old evidence, shown to be correct after all. Something like this seems to be happening to modern science's view of the sun. The current dogma is that the sun is steady, dependable, constant. In this view, its well-known 11-year sunspot cycle is the manifestation of a smoothly running, well-ordered machine, clicking with regularity like astrophysical clockwork. It is a comfortable view, the sun being of some importance to us all here on earth. Now an astronomer with a historical bent has delved back through past observational records and, by making numerous independent cross checks, resurrected and made a persuasive case for an old hypothesis that the solar cycle and the sun itself have changed in historic time. The evidence shows that for a 70-year period from A.D. 1645 to 1715 sunspots were almost totally absent on the surface of the sun. Solar activity was at a near-zero level, a true and strange anomaly. "This is totally unlike the modern behavior of the sun," says the astronomer, John A. Eddy of the National Center for Atmospheric Research's High Altitude Observatory in Boulder, Colo., "and the consequences for solar and terrestrial physics seem to me profound." The evidence shows not only a minimum in solar activity from A.D. 1645 to 1715 but also an earlier minimum from A.D. 1460 to 1550 and an even earlier maximum from A.D. 1 100 to 1250. "We now have to realize," Eddy says, "that the sun's behavior has been better in the last 200 years than in the previous 1,000 years. " The view that solar activity can and has varied to such a major degree in long-term patterns in historic time alters widely accepted assumptions about the constancy of the sun. "We've shattered the Principle of Uniformitarianism for the sun," Eddy says. By this he means that the present behavior of the sun can no longer be considered a reliable guide to the behavior of the sun in the past. Eddy's conclusions imply that the often-discussed 11-year solar cycle is of far less importance and concern than are longer term variations-the overall "envelope" of solar activity. That patterns of solar activity have varied over historic time is interesting enough in itself. But beyond that, Eddy believes that the longterm fluctuations may be due to changes in the solar constant, the total radiative output of the sun. Such an idea is of fundamental importance. Whether the solar constant may vary, once considered improbable, is now being much debated. The problem has taken on new significance as solar physicists and climatologists consider the possible effects of the sun on variations in earth's climate. All this becomes even more intriguing when one observes that the period of near total absence of solar activity from 1645 to 1715 coincides almost precisely with the coldest point in the climatic minimum on earth that we now call the Little Ice Age. As Eddy puts it, "The climate curve looks a lot like the curve of variability in solar activity." Eddy described his results in a session on the sun's effects on terrestrial climate at the annual meeting of the American Association for the Advancement of Science in Boston last week (his paper will appear soon in SCIENCE). When he finished, moderator George B. Field, director of the Center for Astrophysics of the Smithsonian Astrophysical Observatory and the Harvard College Observatory in Cambridge, turned to the small but crowded lecture room and said, "Maybe we've heard a turning point in the history of science." The main contribution of Eddy's analysis is to show that the prolonged sunspot minimum beginning in the 17th century is not an artifact of incomplete or spurious data but is in fact real. This has been the major stumbling block to acceptance of the idea, which has been around since at least the late 19th century. It was then that two well-known solar astronomers, Gustav Sporer of Germany in papers published in 1887 and 1889 and E. W. Maunder of the Greenwich Observatory in more detailed papers published in 1890 and 1894, called attention to the 70-year absence of sunspots. Maunder emphasized

6 citations


Journal ArticleDOI
TL;DR: In this article, a set of numerical experiments is carried out to test the short-range sensitivity of the Goddard Institute for Space Studies global atmospheric general-circulation model to changes in solar constant and ozone amount.
Abstract: A set of numerical experiments is carried out to test the short-range sensitivity of the Goddard Institute for Space Studies global atmospheric general-circulation model to changes in solar constant and ozone amount These experiments consist of forecasts initiated with actual atmospheric data One set of forecasts is made with a standard version of the model; another set uses the model modified by very different values of the solar constant (two-thirds and three-halves of the standard value) and of the ozone amount (zero and twice the standard amount) Twelve-day integrations with these very large variations show such small effects that the effects of realistic variations would almost certainly be insignificant meteorologically on this time scale

4 citations


Journal ArticleDOI
01 Jan 1976
TL;DR: In this article, the authors consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone.
Abstract: Our understanding of the internal structure of the Sun and solar type stars has been undermined by recent observations. In this paper we consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone. The picture that emerges is one of confusion, and so it should be since we have no idea of what is going on inside the Sun and a fortiori of what is going on inside other stars.

Proceedings ArticleDOI
16 Mar 1976
TL;DR: The Active Cavity Radiometer (ACR) as discussed by the authors is an accurate absolute pyrheliometer for measurements of total solar irradiance which has been used to discover a -2.2% error in the International Pyrheliometric Scale and to make measurements in balloon flight experiments yielding a solar constant value of 136.6 (+ or - 0.7) mW/sq cm.
Abstract: The Active Cavity Radiometer (ACR), an accurate absolute pyrheliometer, has been developed for measurements of total solar irradiance. It has been used to discover a -2.2% error in the International Pyrheliometric Scale and to make measurements in balloon flight experiments yielding a solar constant value of 136.6 (+ or - 0.7) mW/sq cm. New ACRs are being developed to monitor the total output of solar optical radiation in balloon, satellite and space shuttle experiments with long-term absolute uncertainty of + or - 0.1% or less. In a separate program, instrumentation for the measurement of the scattering and extinction of solar radiation by the atmosphere is being constructed to provide data for modeling atmospheric aerosol content. The aerosol models will facilitate computation of radiative transfer effects yielding quantitative net fluxes useful in evaluating the climatological impact of aerosols.