scholarly journals Evaluating the Solar Slowly Varying Component at C-Band Using Dual- and Single-Polarization Weather Radars in Europe

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
M. Gabella ◽  
A. Huuskonen ◽  
M. Sartori ◽  
I. Holleman ◽  
M. Boscacci ◽  
...  
Keyword(s):  
Solar Radio ◽  
Reference Signal ◽  
Active Regions ◽  
Solar Radio Emission ◽  
Reference Ranges ◽  
Volume Data ◽  
Horizontal Polarization ◽  
Weather Radars ◽  
Solar Microwave ◽  
Single Polarization

Six C-band weather radars located in Europe (Finland, Netherlands, and Switzerland) have been used to monitor the slowly varying solar emission, which is an oscillation with an amplitude of several decibels and a period of approximately 27 days. It is caused by the fact that the number of active regions that enhance the solar radio emission with respect to the quiet component, as seen from Earth, varies because of the Sun’s rotation about its axis. The analysis is based on solar signals contained in the polar volume data produced during the operational weather scan strategy. This paper presents hundreds of daily comparisons between radar estimates and the Sun’s reference signal, during the current active Sun period (year 2014). The Sun’s reference values are accurately measured by the Dominion Radio Astrophysical Observatory (DRAO) at S-band and converted to C-band using a standard DRAO formula. Vertical and horizontal polarization receivers are able to capture the monthly oscillation of the solar microwave signal: the standard deviation of the log-transformed ratio between radars and the DRAO reference ranges from 0.26 to 0.4 dB. A larger coefficient (and a different value for the quiet Sun component) in the standard formula improves the agreement.

scholarly journals Structural and Evolutionary Features of Flare-Producing Active Regions During 1988-1990

1993 ◽  
Vol 141 ◽  
pp. 388-390
Author(s):  
A. A. Golovko
Keyword(s):  
Solar Activity ◽  
Radio Emission ◽  
Solar Radio ◽  
Active Regions ◽  
Magnetic Activity ◽  
High Solar Activity ◽  
Solar Radio Emission ◽  
Evolutionary Features ◽  
Siberian Solar Radio Telescope ◽  
Flare Productivity

During the period of high solar activity (1988-1990) the Sayan and Baikal Observatories of the ISTP carried out observations of the chromosphere in the H-alpha line, the photosphere and of sunspot magnetic fields; at the Siberian Solar Radio Telescope, solar radio emission observations at 5.2 cm wavelength were made. Using those observations a study is made of the evolution of “centers of magnetic activity” (Bumba, 1986) in nine active regions with different flare productivity, for which the most complete observations were available. In three cases (NOAA Nos. 5229, 5643 and 5669) they were the targets of the cooperative international Max’91 program.

scholarly journals Estimation of Magnetic Field Strength from Enhanced Solar Radio Emission

1994 ◽  
Vol 47 (6) ◽  
pp. 811 ◽  
Author(s):  
SBSS Sarma
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Solar Radio ◽  
Active Regions ◽  
Shock Velocity ◽  
Solar Radio Emission ◽  
Type I ◽  
Radio Noise ◽  
Coronal Magnetic Fields

The manifestation of solar activity on radio noise records at 28.6 MHz is discussed with special emphasis on Type-I noise storms and the associated coronal magnetic fields above the active regions in time. Magnetic fields are estimated, assuming that the Type-I radio emission at decametre wavelengths is due to shock waves, by making use of the observed shock velocity. The results are comparable with the existing estimates.

Polarization features of solar radio emission and possible existence of current sheets in active regions

Solar Physics ◽  
1994 ◽  
Vol 155 (2) ◽  
pp. 339-350 ◽  
Author(s):  
N. Gopalswamy ◽  
V. V. Zheleznyakov ◽  
S. M. White ◽  
M. R. Kundu
Keyword(s):  
Radio Emission ◽  
Solar Radio ◽  
Active Regions ◽  
Solar Radio Emission ◽  
Current Sheets

scholarly journals Properties of sources of the slowly varying component of 2 cm solar radio emission

1968 ◽  
Vol 35 ◽  
pp. 575-580
Author(s):  
V. G. Nagnibeda
Keyword(s):  
High Resolution ◽  
Radio Emission ◽  
Radio Astronomy ◽  
Solar Radio ◽  
Emission Spectra ◽  
Active Regions ◽  
Solar Radio Emission ◽  
Radio Sources ◽  
Pulkovo Observatory ◽  
Local Sources

To study the nature of the local sources of solar radio emission connected with active regions, it is important to investigate the structure of such sources and their emission spectra. These problems are being investigated in detail by a group of workers of the Radio Astronomy Department of the Pulkovo Observatory led by G.B. Gelfreikh. The Pulkovo large radio telescope used for the observations allows them to investigate the solar radio sources at the whole cm-wavelength range with a high resolution reaching 40 sec of arc at the 2-cm wave. Observations are taken at 2·0, 3·2, 4·4, 6·6, and 9-cm waves. The author observes at the 2-cm wave.

Thermal Cyclotron Radiation from Solar Active Regions

1980 ◽  
Vol 86 ◽  
pp. 87-99
Author(s):  
V.V. Zheleznyakov ◽  
E. Ya. Zlotnik
Keyword(s):  
Fine Structure ◽  
Radio Emission ◽  
Frequency Spectrum ◽  
Solar Radio ◽  
Active Regions ◽  
Solar Radio Emission ◽  
Kinetic Temperature ◽  
Frequency Spectra ◽  
Solar Active Regions ◽  
Thermal Cyclotron Radiation

Various frequency spectra with the fine structure resulting from the thermal cyclotron radio emission from solar active regions are discussed. The conditions in sources (distribution of magnetic field and kinetic temperature over the height) are put forward which provide the frequency spectrum as a set of cyclotron lines and high frequency cut-offs. For each kind of distribution the frequency spectrum and polarization are of peculiar character. This permits one to find the conditions in the source through the properties of the observed microwave solar radio emission. To obtain reliable data on the fine structure and judge about conditions in the sources it is necessary to study microwave solar radio emission using the swept-frequency or multi-channel receivers combined with high directional antennae.

Mid-term Periodicities in Solar Radio Emission Corresponding to Sunspot Number During Solar Cycle 23

Solar Physics ◽  
2021 ◽  
Vol 296 (3) ◽  
Author(s):  
Mahender Aroori ◽  
Panditi Vemareddy ◽  
Partha Chowdhury ◽  
Ganji Yellaiah
Keyword(s):  
Solar Cycle ◽  
Radio Emission ◽  
Sunspot Number ◽  
Solar Radio ◽  
Solar Radio Emission ◽  
Solar Cycle 23

Flare-plasma diagnostics from millisecond pulsations of the solar radio emission

2002 ◽  
Vol 46 (6) ◽  
pp. 497-514 ◽  
Author(s):  
V. F. Melnikov ◽  
G. D. Fleishman ◽  
Q. J. Fu ◽  
G.-L. Huang
Keyword(s):  
Radio Emission ◽  
Plasma Diagnostics ◽  
Solar Radio ◽  
Solar Radio Emission ◽  
Flare Plasma
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