In the history of science the opening up of a new observational or experimental window is always followed by an increase in knowledge of the subject concerned. This is also the case with the subject of this book, ultraviolet radiation (hereafter UV). In principle, the ultraviolet range might be just one more of these windows, of no particular importance. However, the energy per UV photon provides the main peculiarity, its magnitude being great enough to produce important ch- ical reactions in the atmospheres of planets and satellites, thereby a?ecting the transmission of this radiation to the ground. The Sun is the main natural source of UV radiation in the Solar System and our planet is the body where its in?uences can be best tested and the only one where its relation with life can be studied. However, the terrestrial atmosphere blocksmostofthephotonsinthiselectromagneticrangeandastronomershavehad to develop various techniques (balloons, planes and rockets) to cross this barrier and access the information. These tools have been used in parallel to investigate the physical properties of the terrestrial atmosphere and the interaction of its constituents with light. This book will addresses most of these topics.

In the history of science the opening up of a new observational or experimental window is always followed by an increase in knowledge of the subject concerned. This is also the case with the subject of this book, ultraviolet radiation (hereafter UV). In principle, the ultraviolet range might be just one more of these windows, of no particular importance. However, the energy per UV photon provides the main peculiarity, its magnitude being great enough to produce important ch- ical reactions in the atmospheres of planets and satellites, thereby a?ecting the transmission of this radiation to the ground. The Sun is the main natural source of UV radiation in the Solar System and our planet is the body where its in?uences can be best tested and the only one where its relation with life can be studied. However, the terrestrial atmosphere blocksmostofthephotonsinthiselectromagneticrangeandastronomershavehad to develop various techniques (balloons, planes and rockets) to cross this barrier and access the information. These tools have been used in parallel to investigate the physical properties of the terrestrial atmosphere and the interaction of its constituents with light. This book will addresses most of these topics.

Presents a collection of essays that discuss the role of the sun in the solar system, and covers such topics as solar winds and storms, magnetism, sunspots, ultraviolet radiation, and solar energy.

The inspiration for this monograph derived from the realization that human technical capacity has become so great that we can, even without malice, substantially modify and damage the gigantic and remote outer limit of our planet, the stratosphere. Above the atmosphere of our ordinary experience, the stratosphere is a tenuous layer of gas, blocked from rapid exchange with the troposphere, some twenty kilometers above the surface of the earth, seldom reached by humans, and yet a fragile shell which shields life on earth from a band of solar radiation of demonstrable injurious potential. It is immediately obvious that if stratospheric ozone were reduced and consequently the intensity of solar ultraviolet radiation reaching the earth's surface were increased, then human skin cancer, known to be related to solar ultraviolet exposure, would also be increased. But how does one even begin to estimate the impact of changed solar ultraviolet radiation on such a diverse. interacting, and complex ecosystem as the oceans? Studies which I conducted in Iceland focused on this question and were noted to the Marine Sciences Panel of the Scientific Affairs Committee of NATO by Professor Unnsteinn Stefansson, leading to a request to investigate the possibility of organizing a NATO sponsored Advanced Research Institute on this topic.

Following the rapid developments in the UV-B measurement techniques and the rapidly growing research in the field in the late 80's and early 90's, we organized a large gathering of distinguished experts in a NATO Advanced Study Institute, held in Halkidiki, Greece on October, 2-11. 1995. The Institute was organized so as to include state of the art lectures on most aspects of solar ultraviolet radiation and its effects. This was achieved by extended lectures and discussions given in five sessions by 27 lecturers and a demonstration of filed measurements and calibration techniques at the end of the Institute. The ASI began with the sun and fundamentals on solar radiative emissions and their variability in time and continued with the interaction of solar Ultraviolet with the atmosphere through the complex scattering processes and photochemical reactions involved. Particular emphasis was given to changes in atmospheric composition imposed by different manifestations of the solar activity cycle. as well as on the modelling of radiative transfer through the atmosphere and the ocean under variable environmental conditions. Overviews on the ozone issue. its monitoring and variability were 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 world-wide distributed stations.

Are variations in the energy generated by the Sun sufficient to modify the Earth's global environment at levels comparable to expected anthropogenic changes? Debated contentiously for more than a century, this question must now be posed with new urgency: the proper specification of natural global changes is a prerequisite for detecting anthropogenic impacts. Important advances over the past decade in our knowledge of the Sun and of the terrestrial responses to solar variability provides the basis for answering this question with unprecedented surety, but significant uncertainties remain. This book addresses current monitoring and understanding of solar influences on both the climate system and the ozone layer and prioritizes the research effort that will be needed to provide a sound scientific basis for policymaking related to global change issues.

Presents a contemporary picture of the solar system, including a description of the Earth, Mars, Venus, cratered worlds, exotic rocks and ices, and giant planets. It is pitched at an introductory level and assumes no previous knowledge of planetary astronomy. Little mathematics is used in the text and the numerous graphs and diagrams are kept as simple as possible. End of chapter exercises are provided. The book can be used as an end in itself, or as a preparation for more advanced study, for which references are given.

Numerous studies report that ultraviolet (UV) radiation is harmful to living organisms and detrimental to human health. Growing concerns regarding the increased levels of UV-B radiation that reach the earth's surface have led to the development of ground- and space-based measurement programs. Further study is needed on the measurement, modeling, and effects of UV radiation. The chapters of this book describe the research conducted across the globe over the past three decades in the areas of: (1) current and predicted levels of UV radiation and its associated impact on ecosystems and human health, as well as economic and social implications; (2) new developments in UV instrumentation, advances in calibration (ground- and satellite-based), measurement methods, modeling efforts, and their applications; and (3) the effects of global climate change on UV radiation. Dr. Wei Gao is a Senior Research Scientist and the Director of the USDA UV-B Monitoring and Research Program, Natural Resource Ecology Laboratory, Colorado State University. Dr. Gao is a SPIE fellow and serves as the Editor-in-Chief for the Journal of Applied Remote Sensing. Dr. Daniel L. Schmoldt is the National Program Leader for instrumentation and sensors at the National Institute of Food and Agriculture (NIFA) of the U.S. Department of Agriculture. Dr. Schmoldt served as joint Editor-in-Chief of the journal, Computers & Electronics in Agriculture, from 1997 to 2004. Dr. James R. Slusser retired in 2007 from the USDA UV-B Monitoring and Research Program at Colorado State University. He was active in the Society of Photo-Optical Instrumentation Engineers, the American Geophysical Union, and the American Meteorological Society. Dr. Slusser is currently pursuing his interests in solar energy and atmospheric transmission.