Search

There is a need today to recreate the Havana observational solar station because of the importance of obtaining a regular forecast of solar activity in a wide range of time intervals. The concept of the created observation network and the infrastructure of the monitoring station as a network element are described in detail. The functions of this network will provide continuous observational material for the Russian Sun and Space Weather Services and will be independent of space observations, but capable of using them for quality control. The physical foundations of complex observations for a wide range of heliogeophysical phenomena are considered. [ABSTRACT FROM AUTHOR]

The study involves the obtainment of regular tracers of the solar cycle in the radio range by activity manifestations in the chromosphere and corona. Our research method consists of the systematic processing of the RATAN-600 radio data at frequencies 3–18 GHz obtained during more than one cycle of solar activity and their comparison with other databases of time series characterizing the magnetic activity of the Sun at the photospheric level. In the first phase of this work, we identified an array of approximately 600 active regions that evenly covers all phases of solar cycle 24 in approximately 9 years, for which we reliably identified the local radio sources based on RATAN-600 data, as well as data from other databases, such as spacecraft of the Space Weather Prediction Center of the National Oceanic and Atmospheric Administration and the Solar Dynamics Observatory. The sample is statistically homogeneous and evenly distributed over solar latitudes in both hemispheres. The statistical relationships between the sunspot areas and the parameters of intensity and polarization of local radio sources are obtained. It is shown how the spectral flux density of local radio sources in the chromosphere and corona at different frequencies increases with the increase in the sunspot area (and, consequently, the magnetic flux). The estimates of exponents of this dependence are obtained. [ABSTRACT FROM AUTHOR]

We present the results of forecasting flare activity based on the data from microwave spectropolarimetric observations of active regions (ARs) obtained with the RATAN-600 radio telescope and the X-ray data from the GOES satellite as well as monitoring data. The method is designed for short-term (1-3-days) flare forecasts. Proton events are considered as part of the general flare problem. Obtaining a reliable forecast is a difficult process in view of the multi-parameter and multi-dimensional system of plasma parameter variations and multiple non-linear interconnections.We used a modified Tanaka-Enome criterion, as well a database of observational material collected over many years. The forecasting efficiency was analyzed depending on the threshold values of the criterion. We show that the quality of the radio astronomical forecast is determined by the level of sensitivity of the detector at short centimeterwavelengths and by the solar activity level. [ABSTRACT FROM AUTHOR]

Application of the mode of azimuthal observations on RATAN-600 has made it possible to realize multiple daily observations [1]. The results of multiwavelength observations of the Sun in this mode point to the existence of sharp spectral irregularities in the polarized radiation of flare-productive active regions (FPARs) producing especially powerful flares [2]. These phenomena occur in a broad range of radio-emission fluxes (0.05–200 s.f.u.), in a rather narrow wavelength band (2–5 cm), and they are recorded during the time interval from several hours to several days before a powerful flare, as well as during the flare. Frequently, such events indicate an eruption of powerful coronal mass ejections and high-energy particle (proton) fluxes, which, when reaching the Earth’s magnetosphere, trigger its disturbances. Here, we analyze events in the microwave band connected with the strongest flares which took place on October 28 and November 4, 2003. [ABSTRACT FROM AUTHOR]

We present new observational data on the phenomena of extremely high activity on the Sun and in the heliosphere that took place in October-November 2003. A large variety of solar and heliospheric parameters give evidence that the interval under consideration is unique over the entire observation time. Based on these data, comparing them with similar situations in the past and using available theoretical concepts, we discuss possible cause-and-effect connections between the processes observed. The paper includes the first results and conclusions derived by the collaboration "Solar Extreme Events-2003" organized in Russia for detailed investigations of these events. As a result of our consideration, it is beyond question that the physical causes of solar and heliospheric phenomena in October-November 2003 are not exclusively local and do not belong only to the active regions and solar atmosphere above them. The energy reservoirs and driving forces of these processes have a more global nature. In general, they are hidden from an observer, since ultimately their sources lie in the subphotospheric layers of the Sun, where changes that are fast and difficult to predict can sometimes take place (and indeed they do). Solar flares can serve as sufficiently good tracers of these sudden changes and reconstructions on the Sun, although one can still find other diagnostic indicators among the parameters of magnetic fields, motions of matter, and emission characteristics. [ABSTRACT FROM AUTHOR]