Continuing its tradition of bringing the international community together annually at Sacramento Peak to review and discuss the most recent results in various topics in solar physics, this year NSO hosted the "Solar Electromagnetic Radiation Study for Solar Cycle 22" (SOLERS22) 1996 Workshop during the week of June 17. This workshop was a fine match for NSO's workshop series because it considered both basic physical processes on the Sun and their terrestrial consequences, and because NSO leads the Precision Solar Photometric Telescopes (PSPT) component of the NSF-sponsored Radiative Inputs from the Sun to Earth (RISE) program.
SOLERS22 has been organized under the auspices of the Solar-Terrestrial Energy Program (STEP) Working Group on "The Sun as a Source of Energy and Disturbances". STEP is sponsored by the Scientific Committee on Solar Terrestrial Physics (SCOSTEP) of the International Council of Scientific Unions (ICSU).
The main goals of SOLERS22 are to monitor, study, model, and interpret the observed changes in the solar electromagnetic radiation, both bolometric and in spectral bands from X-ray to infrared and radio. Since the Sun is a representative of one class of stars showing cyclic variability, the study of the variability of solar-type stars is also an important interest of SOLERS22. Understanding and predicting solar variability, especially on long time scales, is of extraordinary practical importance because the solar radiative output is one of the major natural driving forces of the terrestrial atmosphere and climate system. Therefore, SOLERS22 is also concerned about the climate impact of solar variability.
More than 100 scientists from many countries attended this year's meeting. Variations in solar and stellar irradiances and the climate impact of solar variability were discussed in detail. The contributed papers will be refereed and published in Solar Physics. The Workshop Proceedings will be edited by Judit Pap, Claus Fröhlich, and Roger Ulrich and published by Kluwer Academic Publishers.
Results presented during the Workshop demonstrate that considerable progress has been made since the SOLERS22 Workshop held in 1991. Several new measurements of solar irradiance have been performed from space, from the Upper Atmosphere Research Satellite (UARS), the ATLAS and EURECA missions, and more recently from the SOHO mission. These space-borne observations of the solar radiation have confirmed that solar total and spectral irradiances have indeed changed in parallel with the solar magnetic activity cycle. In addition to space observations, considerable efforts have been made in improving the ground-based observations of solar activity. Since the satellite-based irradiance monitoring experiments observe the Sun as a star, high quality, spatially resolved images are necessary to reveal and interpret the causes of the observed irradiance changes. In addition to the ground-based observations of solar variability, several experiments on the SOHO mission provide high resolution solar images to study solar variability on time scales from minutes to years. Results presented at the SOLERS22 1996 Workshop have demonstrated that considerable efforts have been put forward to improve irradiance models using the results of image decomposition techniques and new statistical methods. Coupling the studies of changes in solar irradiance and the frequency of solar oscillations, as well as the solar radius, have provided an additional tool for probing the solar interior and to study the physical causes of irradiance changes.
Since the current STEP project and its activities will expire in December 1997, the Workshop participants discussed the future of SOLERS22. SOLERS22 members and Workshop participants agreed that the near-term SOLERS22 effort will concentrate on the following: 1) producing a reference solar spectrum from X-ray to far infrared for solar minimum between cycles 21 and 22; 2) gathering information about the solar cycle dependence of spectral irradiance changes; and 3) improving physical models of solar irradiance variability by incorporating the results gained from image analysis, radius measurements, and studying the frequency changes of p-mode oscillations. A better understanding of the physical causes of irradiance changes will certainly lead to improvement of the reliability of climate models. Based on the discussions during the SOLERS22 1996 Workshop, a continuation of SOLERS22 in the post-STEP era, during the period 1998-2002, has been proposed to SCOSTEP.
The Workshop was sponsored by the Air Force Office of Scientific Research (AFOSR)/ European Office of Aerospace Research and Development; AFOSR/Asian Office of Scientific Research and Development; Jet Propulsion Laboratory, California Institute of Technology; National Aeronautics and Space Administration; National Optical Astronomy Observatories, National Solar Observatory; Scientific Committee on Solar-Terrestrial Physics (SCOSTEP); Solar-Terrestrial Energy Program (STEP); and University of California, Los Angeles.
The Scientific Organizing Committee consisted of R.P. Cebula, R.F. Donnelly, F. Farnik, C. Fröhlich (Co-Chair), D. Gillotay, K. Harvey, D.F. Heath, J. Kuhn, A. Mecherikunnel, L. November (Co-Chair), H. Ogawa, J.M. Pap (Chair), G.J. Rottman, P.C. Simon, G. Thuillier, W.K. Tobiska, C.H. Wehrli, T.N. Woods. The Local Organizing Committee consisted of R. Altrock, R. Coleman, R. Elrod, R. Hunter (Chair), R. Kariyappa, J. Kuhn, L. November.
Judit Pap, Claus Fröhlich, Dick Altrock