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Publications and source records attributed to Pap, Judit.
The solar chromosphere consists of three classes-- plage, network, background -- which contribute differently to ultraviolet radiation reaching the earth. Solar physicists are interested in relating plage area and intensity to UV irradiance, as well as understanding the spatial and temporal evolution of plage shapes.
Solar irradiance in the near-UV (335 nm), visible (500 nm) and infrared (778 nm) spectral bands has been measured by the SunPhotometers developed at the World Radiation Center, Davos, Switzerland on board the European Retrievable Carrier between August 1992 and May 1993. Study of the variations in the visible and infrared irradiance is important for both solar and atmospheric physics. The purpose of this paper is to examine the temporal variations observed in the visible and infrared spectral bands after eliminating the trend in the data mainly related to instrument degradation. The effect of active regions in these spectral irradiances is clearly resolved. Variations in the visible and infrared irradiances are compared to total solar irradiance observed by the SOVA2 radiometer on the EURECA platform and by the ACRIMII radiometer on UARS as well as to UV observations of the UARS and NOAA9 satellites. The space-borne spectral irradiance observations are compared to the photometric sunspot deficit and CaII K irradiance measured at the San Fernando Observatory, California State University at Northridge in order to study the effect of active regions in detail.
The detection of variations in solar irradiance by satellite-based experiments during the last 17 years stimulated modelling efforts to help to identify their causes and to provide estimates for irradiance data when no satellite observations exist.
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The preliminary results of the photometry of CaII K spectroheliograms taken at the NationalSolar Observatory at Sacramento peak are presented in this paper. We have digitizedspectroheliograms for 1980 (maximum of SC21), 1985 (minimum of SC21), 1987 (beginning of theascending phase of SC22), 1988 and 1989 (ascending phase and maximum of SC22), and 1992(declining phase of SC22). We have analyzed images for 1992 and separated the plages, the magneticnetwork, internetwork elements and the chromospheric background using histogram method. Wehave derived the intensity and area of these features as well as the full disk intensity (Spatial KIndex). The Spatial K Index has been compared to the spectral Ca K index derived from the lineprofiles and total solar and UV irradiance measured by the UARS and NOAA9 satellites. Thecontribution of plages, the magnetic network and internetwork element to the changes observed intotal solar and UV irradiances are also estimated.
Analyses based on irradiance observations from space within the last one and a half decades have.
Analyses based on irradiance observations from space within the last one and a half decades have.
The preliminary results of the photometry of CaII K spectroheliograms taken at the National Solar
Study of changes in solar and stellar irradiances has been of high interest for a long time. Determining the absolute value of the luminosity of stars with different ages is a crucial question for the theory of stellar evolution and energy production in stellar interiors.
Continuous Measurements of the Solar UV have been made by an instrument on the Solar Mesosphere Explorer (SME) since October 1981. The results for the wavelength interval 200 to 300 nm show an irradiance decrease to a minimum in early 1987 and a subsequent increase to mid-April 1989. The observed UV changes during part of solar cycles 21 to 22 represent approx. 35 percent (during the decreasing phase) and 25 percent (during the increasing phase) of the observed variations of the solar constant for the same time period as the SME measurements.