........ published in NEWSLETTER # 64
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........ published in NEWSLETTER # 64
SOLAR ULTRAVIOLET RADIATION, MODELING, MEASUREMENTS AND EFFECTS
by Professor C.S. Zerefos, Aristotle University, Thessaloniki (Greece)
The ASI proceedings (NATO ASI SERIES I52) begin with the sun and fundamentals on solar radiative emissions and their variability in time and continue with the interaction of solar ultraviolet radiation with the atmosphere through the complex scattering processes and photochemical reactions involved. Particular emphasis is given to changes in atmospheric composition imposed by different manifestations of the solar activity cycle, as well as to the modeling of radiative transfer through the atmosphere and the ocean under variable environmental conditions.
Overviews on the ozone issue, its monitoring and variability are extensively discussed with emphasis on the observed acceleration of ozone decline in the early 90's. This acceleration had as a consequence, significant increases in UV-B radiation observed at a few worldwide distributed stations. Both the spatial and temporal UV variability and its monitoring principles are extensively discussed along with the required quality assurance and quality control of this sensitive part of the solar spectrum. State-of- the-art modeling of stratospheric ozone and the perspective of related global issues are thoroughly discussed.
Several contributions discuss the effects of aerosols on UV transmittance and scattering as well as the effects of volcanic aerosols on photochemistry. An extensive discussion is dedicated to the effects of El Chichon and particularly Pinatubo in changing the ozone and UV fields. On the other hand, under the enhanced UV levels which accompany the ozone decline, important changes are expected in the oxidizing capacity of the atmosphere including changes in ozone and other active atmospheric species. In addition to modeling and observations, instrumentation techniques on UV measurements with emphasis given to spectroradiometric methods, errors and calibration techniques are discussed. An overview of the results of large spectroradiometer campaigns and methodologies involved has shown that at 300 nm or so, the interinstrumental accuracy of 5-10 % imposes an error limit in the detection of these biologically important wavelengths. Finally, personal exposure problems of UV as well as its effects on terrestrial and marine ecosystems and its role in causing skin cancer are also among the important effects discussed in this volume.
Reference books: G8, I7, I18, I32, I42, I52