Contribution of Ultraviolet Irradiance Variations to Changes in the Sun's Total Irradiance

The sun's total irradiance decreased from 1980 to mid-1985, remained approximately constant until mid-1987, and has recently begun to increase. This time interval covered the decrease in solar activity from the maximum of solar cycle 21 to solar minimum and the onset of cycle 22. The sun's ultraviolet irradiance also decreased during the descending phase of cycle 21 and, like the total irradiance, is now increasing concurrently with the increase in cycle 22 activity. Although only 1 percent of the sun's energy is emitted at ultraviolet wavelengths between 200 and 300 nanometers, the decrease in this radiation from 1 July 1981 to 30 June 1985 accounted for 19 percent of the decrease in the total irradiance over the same period.     

A model of solar luminosity modulation by magnetic activity between 1954 and 1984

A simple model based on the changes in excess radiation from bright magnetic faculae and on changes in reduced radiation from dark spots is remarkably successful in matching the slow variations of total solar irradiance measured simultaneously by the ERB and ACRIM satellite radiometers between 1981 and 1984. This model was extended back to 1954 to reconstruct the modulation of irradiance by magnetic activity during the past three 11-year solar cycles. The model predicts that the sun is consistently brighter at activity maximum than at minimum. The 0.07 percent brightening at the peak of the last cycle in 1980 was more pronounced than the brightenings found for either of the two previous cycles, even though cycle 19, which peaked around 1957, had the largest sunspot number amplitude in the history of reliable sunspot records.     

Solar cycle variability, ozone, and climate

Results from a global climate model including an interactive parameterization of stratospheric chemistry show how upper stratospheric ozone changes may amplify observed, 11-year solar cycle irradiance changes to affect climate. In the model, circulation changes initially induced in the stratosphere subsequently penetrate into the troposphere, demonstrating the importance of the dynamical coupling between the stratosphere and troposphere. The model reproduces many observed 11-year oscillations, including the relatively long record of geopotential height variations; hence, it implies that these oscillations are likely driven, at least in part, by solar variability.     

Astronomy and solar physics: measurement of the solar spectral irradiance from 200 to 3000 nanometers

The solar spectrum experiment on Spacelab 1 measured 98 percent of the sun's total energy output. It improved the absolute accuracy of solar irradiance data, especially in the ultraviolet and infrared regions. In order to detect any variation in the spectrum on future shuttle flights, the data were obtained in a radiation scale that can be preserved with high precision over many years. The instrument performance and preliminary data reduction are described.     

The Impact of Solar Variability on Climate

A general circulation model that simulated changes in solar irradiance and stratospheric ozone was used to investigate the response of the atmosphere to the 11-year solar activity cycle. At solar maximum, a warming of the summer stratosphere was found to strengthen easterly winds, which penetrated into the equatorial upper troposphere, causing poleward shifts in the positions of the subtropical westerly jets, broadening of the tropical Hadley circulations, and poleward shifts of the storm tracks. These effects are similar to, although generally smaller in magnitude than, those observed in nature. A simulation in which only solar irradiance was changed showed a much weaker response.     

Ozone and temperature trends associated with the 11-year solar cycle

Evidence is presented which suggests that trends in the ozone concentration and stratospheric temperature, reported between the early 1960's and 1976, are to a large extent due to solar ultraviolet flux variability associated with the 11-year solar cycle. Radiative-convective-photochemical simulations of ozone and temperature variations have been made with a solar ultraviolet flux variability model. Results for temperatures and ozone concentrations, when compared with published data, show good agreement.     

Length of the solar cycle: an indicator of solar activity closely associated with climate

It has recently been suggested that the solar irradiance has varied in phase with the 80- to 90-year period represented by the envelope of the 11-year sunspot cycle and that this variation is causing a significant part of the changes in the global temperature. This interpretation has been criticized for statistical reasons and because there are no observations that indicate significant changes in the solar irradiance. A set of data that supports the suggestion of a direct influence of solar activity on global climate is the variation of the solar cycle length. This record closely matches the long-term variations of the Northern Hemisphere land air temperature during the past 130 years.     

Stratospheric ozone with added water vapor: influence of high-altitude aircraft

Simple, steady-state models for ozone photochemistry, radiative heat balance, and eddy-diffusive mass transport can be combined to estimate water-induced changes in the stratospheric ozone concentrations and temperatures, the integrated ozone column, the solar power transmitted to the earth's surface, and the surface temperature. These changes have been computed parametrically for mixing fractions of water vapor between 3 x 10(-6) and 6.5 x 10(-6). With added water from the exhausts of projected fleets of stratospheric aircraft, the ozone column may diminish by 3.8 percent, the transmitted solar power increase by 0.07 percent, and the surface temperature rise by 0.04 degrees K in the Northern Hemisphere. Due to a cancellation of terms, temperatures in the lower stratosphere remain essentially unchanged. These results are sensitive to the form of the water profile and emphasize the potential role of convective transients near 30 kilometers.     

Observations of solar irradiance variability

High-precision measurements of total solar irradiance, made by the active cavity radiometer irradiance monitor on the Solar Maximum Mission satellite, show the irradiance to have been variable throughout the first 153 days of observations. The corrected data resolve orbit-to-orbit variations with uncertainties as small as 0.001 percent. Irradiance fluctuations are typical of a band-limited noise spectrum with high-frequency cutoff near 0.15 day(-1) their amplitudes about the mean value of 1368.31 watts per square meter approach +/- 0.05 percent. Two large decreases in irrradiance of up to 0.2 percent lasting about 1 week are highly correlated with the development of sunspot groups. The magnitude and time scale of the irradiance variability suggest that considerable energy storage occurs within the convection zone in solar active regions.     

太阳辐射减弱和臭氧浓度增加对大豆荧光特性与产量的影响

【目的】研究太阳辐射减弱和臭氧（O3）浓度增加单因子及复合作用条件下对大豆荧光特性与产量的影响,为应对两因素对我国农作物的不利影响提供基础理论依据。【方法】以八月黄大豆品种为试材,采用大田开顶式气室（OTC）进行太阳辐射减弱和O3浓度增加单因子及其复合条件下对大豆荧光特性与产量的影响试验。试验设4个处理,分别为：CK（不通O3、不作辐射减弱处理）、T1（不通O3,辐射减弱20％）、T2（100nL／LO3处理）、T3（100nL／LO3和辐射减弱20％复合处理）。【结果】相对于CK,T1、T2、T3处理条件下大豆的Pm、Ik、Yield、qP显著下降;L（PFD）、NPQ、Y（NPQ）、（1-qP）／NPQ显著增大;T1、T2、T3处理对快速光响应曲线的初始斜率（α）没有明显影响;T1处理对Fv/Fm值无明显影响,T2、T3处理的Fv/Fm。值显著下降;T1处理的Y（NO）值显著增大,T2处理的Y（NO）值显著减小,而T3处理没有显著改变Y（NO）值。相对于CK,T1、T2、T3处理条件下大豆的固氮能力、生物量和产量均显著降低,且呈T1〈T2〈T3的趋势。【结论】太阳辐射减弱和O3浓度增加复合条件下相对于单因子胁迫具有更明显的胁迫效应,但复合效应小于单因子胁迫效应的简单累加。太阳辐射减弱和O3浓度增加在很大程度上影响了大豆的光合作用,造成大豆减产。     

An empirical model of total solar irradiance variation between 1874 and 1988

An empirical model of variations in the total solar irradiance caused by observed changes in photospheric magnetic activity between 1874 and 1988 is presented. The model provides a remarkably good representation of the irradiance variations observed by satellite-borne radiometers between 1980 and 1988. It suggests that the mean total irradiance has been rising steadily since about 1945, with the largest peak so far at about 1980 and another large peak expected during the current solar cycle 22. But it is doubtful whether even this rise can contribute significantly to global warming, unless the temperature increase of about 0.02 degrees C that it produces in current energy balance models seriously underestimates the sensitivity of climate to solar irradiance changes.     

大气辐射在臭氧反演中的应用

阐述了大气臭氧含量的量度方法,然后在综合分析国内外大量相关文献的基础上,总结归纳了利用太阳透射辐射、太阳紫外散射、红外辐射及微波辐射等大气辐射进行大气臭氧反演的方法、特点及应用,最后总结了利用大气辐射进行臭氧反演的现状及在臭氧探测中应该注意的问题。     

Biological weighting function for the inhibition of phytoplankton photosynthesis by ultraviolet radiation

Severe reduction of stratospheric ozone over Antarctica has focused increasing concern on the biological effects of ultraviolet-B (UVB) radiation (280 to 320 nanometers). Measurements of photosynthesis from an experimental system, in which phytoplankton are exposed to a broad range of irradiance treatments, are fit to an analytical model to provide the spectral biological weighting function that can be used to predict the short-term effects of ozone depletion on aquatic photosynthesis. Results show that UVA (320 to 400 nanometers) significantly inhibits the photosynthesis of a marine diatom and a dinoflagellate, and that the effects of UVB are even more severe. Application of the model suggests that the Antarctic ozone hole might reduce near-surface photosynthesis by 12 to 15 percent, but less so at depth. The experimental system makes possible routine estimation of spectral weightings for natural phytoplankton.     

Anthropogenic and natural influences in the evolution of lower stratospheric cooling

Observations reveal that the substantial cooling of the global lower stratosphere over 1979-2003 occurred in two pronounced steplike transitions. These arose in the aftermath of two major volcanic eruptions, with each cooling transition being followed by a period of relatively steady temperatures. Climate model simulations indicate that the space-time structure of the observed cooling is largely attributable to the combined effect of changes in both anthropogenic factors (ozone depletion and increases in well-mixed greenhouse gases) and natural factors (solar irradiance variation and volcanic aerosols). The anthropogenic factors drove the overall cooling during the period, and the natural ones modulated the evolution of the cooling.     

Solar proton event: influence on stratospheric ozone

Large-scale reductions in the ozone content of the middle and upper stratosphere over the polar cap regions were associated with the major solar proton event of 4 August 1972. This reduction, which was determined from measurements with the backscattered ultraviolet experiment on the Nimbus 4 satellite, is interpreted as being due to the catalytic destruction of ozone by odd-nitrogen compounds (NO(x)) produced by the event.     

Possible consequences of nearby supernova explosions for atmospheric ozone and terrestrial life

Hard x-ray pulses or increased cosmic radiation originating in nearby supernova explosions may be capable of temporarily removing most of the earth's atmospheric ozone cover even when direct radiation effects at the earth's surface are negligible. Consequently, terrestrial life may be subject to relatively huge solar ultraviolet fluxes every few hundred million years.     

Stratospheric Nitric Oxide: Measurements during Daytime and Sunset

Measurements of the temporal variation in the stratospheric nitric oxide concentration covering a time period from 11:00 to 20:30 local time show the effect of solar ultraviolet sunset. The experimental results strongly support the theorized role of nitric oxide as a catalyst in the destruction of ozone and its importance in the stratospheric ozone balance.     

The Sun's Influence on the Earh's Atmosphere and Interplanetary Space

The bulk of the sun's radiation is in the visible and infrared. Solar radiation at these wavelengths controls the weather in the lowest levels of the earth's atmosphere. The rate at which this energy is emitted (the so-called solar constant) varies by a few tenths of 1 percent over a time scale of days. Longer period variations may exist, but have yet to be detected. Far more variable are the amounts of energy emitted as ultraviolet, extreme ultraviolet, and x-rays, and in the continuous outflow of ionized solar particles. The latter controls the properties of the space between the earth and the sun as well as those of the earth's magnetosphere. The ultraviolet and particle emissions control the properties of the earth's upper atmosphere, including the global wind circulation and changes therein associated with intense auroral storms. While considerable progress has been made in exploring the solar-terrestrial system since the advent of space research, many problems remain. These include the question of how magnetic energy is converted into ionized particle energy in the sun and in the earth's magnetosphere, the way in which solar and terrestrial magnetic fields join or merge, and how large electric fields are generated and sustained a few thousand kilometers above the earth's poles. Perhaps the most intriguing question concerns the possible relation between solar variability and the earth's weather and climate.     

Long-term brightness variations of neptune and the solar cycle modulation of its albedo

The visual brightness and albedo of Neptune vary periodically during the 11-year solar cycle with an amplitude of 4%, anticorrelated with the variation of solar ultraviolet output. A seasonal trend in color suggests that Neptune, like Uranus, may have a slightly reddened pole.     

Changes in stratospheric ozone

The ozone layer in the upper atmosphere is a natural feature of the earth's environment. It performs several important functions, including shielding the earth from damaging solar ultraviolet radiation. Far from being static, ozone concentrations rise and fall under the forces of photochemical production, catalytic chemical destruction, and fluid dynamical transport. Human activities are projected to deplete substantially stratospheric ozone through anthropogenic increases in the global concentrations of key atmospheric chemicals. Human-induced perturbations may be occurring already.