Search

Proper numerical simulation of the Earth’s climate change requires reliable knowledge of solar irradiance and its variability on different time scales, as well as the wavelength dependence of this variability. As new measurements of the solar spectral irradiance have become available, so too have new reconstructions of historical solar irradiance variations, based on different approaches. However, these various solar spectral irradiance reconstructions have not yet been compared in detail to quantify differences in their absolute values, variability, and implications for climate and atmospheric studies. In this paper we quantitatively compare five different reconstructions of solar spectral irradiance changes during the past four centuries, in order to document and analyze their differences. The impact on atmosphere and climate studies is discussed in terms of the calculation of short wave solar heating rates. [ABSTRACT FROM AUTHOR]

A mechanism is proposed for the generation of zebra-patterns in solar radio bursts due to the excitation of nonlinear ion-sound waves in a nonisothermal plasma and their scattering on fast particles. The appearance of the ion sound at the fundamental frequency can take place in the interaction of two opposing Alfvén or whistler waves. The presence of quasi-equidistant stripes in electro-magnetic radiation is ultimately determined by weak ion-sound dispersion resulting in the formation of higher harmonics. [ABSTRACT FROM AUTHOR]

Polarization measurements of type III bursts at 23.5 and 29.5 MHz have been compared for several years with indicators of magnetic fields in different height levels such as sunspot data, S-component characteristics, and noise storm data. By applying the Mount-Wilson and Brunner types of the related spot groups there results a positive relationship between the average degree of type III burst polarization and the magnitude or complexity of photospheric magnetic fields. For other parameters (leading spot area, peak intensity of the S-component at 9.1 cm wavelength) such a clear monotonic relation has not been found. Possibly the degree of polarization is influenced by height variations of the emitting level of the type III bursts at a fixed frequency due to variable electron densities. No connection has been detected between the type III burst polarization and noise storm fluxes which may be due to the local distance of the origin of both emissions. [ABSTRACT FROM AUTHOR]

Simultaneous observations of spectra and polarization of two noise storms with high time resolution have been performed in IZMIRAN during the periods: May 17-23 and June 7-13, 1969. The results of the analysis show that for different noise storms Type I bursts and chains of Type I bursts possess different spectral and polarization characteristics and different tendencies in variation of these characteristics from day to day. In particular, the first stage of the noise storm in May presented some Type I bursts which displayed a varying degree of polarization within their individual lifetimes. In addition, 112 Type III bursts with weak or moderate polarization were observed. [ABSTRACT FROM AUTHOR]