Solar Influences on Global Change (1994) / Chapter Skim
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EXECUTIVE SUMMARY
EXECUTIVE SUMMARY
Pages 1-12
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From page 1... ...
Observations indicate as well that changes in ultraviolet radiation and energetic particles from the Sun, also connected with solar activity, modulate the layer of ozone that protects the biosphere from solar ultraviolet radiation. This report reassesses solar influences on global change in the light of this new knowledge of solar and atmospheric variability.
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From page 2... ...
There are no firm plans at present to implement the primary recommendation of this report, a program of continuous monitoring of solar irradiance to provide the data needed to diagnose and interpret solar influences on climate change. Because current solar radiometric techniques are insufficiently accurate, ensuring data continuity over many decades will require a series of space based observations with sufficient temporal overlap for calibration transfer and prevention of data loss from instrument failure.
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From page 3... ...
Thus, during the recent descending phase of the 11-year solar activity, solar forcing canceled much of the net anthropogenic forcing. The climate system's response to various forcings depends on the history, altitude, and latitude of the forcing and the climate sensitivity, V'.
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From page 4... ...
The coincidence of the Sun's Maunder Minimum with the lowest temperatures of the Little ice Age is the best documented of such associations in the recent past. That a physical mechanism might be responsible for the similarity of the historical climate and solar activity records has become more plausible because of observational proof that the Sun's radiative output varied throughout the only ~ i-year activity cycle during which it has thus far been monitored (Wilison and Hudson, 1991~.
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From page 5... ...
Both the solar ultraviolet radiative energy and the energetic particle output are modulated by solar activity. The Sun's UV radiation is an order of magnitude more variable than the visible solar radiation that penetrates to the Earth's surface, and these variations generate natural changes in the ozone layer.
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From page 6... ...
Determining whether an observed ozone recovery in the twenty-first century is the consequence of successful CFC mitigation or, instead, of increased solar activity will require continuous, reliable monitoring of solar energy inputs to the middle atmosphere. As well as the UV irradiance, sporadic solar influences, such as energetic particles that may destroy ozone for periods of days to many months, must also be understood.
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From page 7... ...
Solar energy inputs control the state of the Earth's upper atmosphere where spacecraft orbit, and efficient use of space requires operational understanding of the variability of the upper atmosphere, a part of the global Earth system that is highly sensitive to solar forcing. in the context of global change within the upper atmosphere, know1edge of solar forcing is essential.
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From page 8... ...
It is tightly coupled to the upper atmosphere and is also involved in the global electric circuit. Any study of solar influences on global change must therefore consider potential coupling to the biosphere.
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From page 9... ...
The appearance and disappearance of bright active regions throughout the ~ i-year activity cycle control the solar radiative output variations that perturb the Earth's ozone layer and also, more dramatically, the upper regions of the Earth's atmosphere. Energetic particles traveling from the Sun to the Earth are guided by lines of the solar and terrestrial magnetic fields, while the solar wind continually transports plasmas and magnetic fields to the Earth's near-space environment.
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From page 10... ...
It may be obtained through analysis and interpretation of solar images and surrogates that connect the changes in global solar energy output to the fundamental physical parameter changes underlying all solar variability, the magnetic field. Records of solar activity during the past few thousand years can serve as surrogates for solar energy inputs to Earth, providing the physical connections are adequately understood.
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From page 11... ...
8. Understand convection, turbulence, oscillations, and magnetic field evolution in the solar plasma so as to develop techniques for assessing solar activity levels in the past and to predict them in the future.
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From page 12... ...
~ ~ . Monitor globally over long periods the basic structure of the lower thermosphere and upper mesosphere so as to properly define the present structure and its response to solar forcing.
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