SOLAR CYCLE VARIATIONS OF THE OCCURRENCE OF CORONAL TYPE III RADIO BURSTS AND A NEW SOLAR ACTIVITY INDEX
- School of Physics, University of Sydney, New South Wales (Australia)
This Letter presents the results of studies of solar cycle variations of the occurrence rate of coronal type III radio bursts. The radio spectra are provided by the Learmonth Solar Radio Observatory (Western Australia), part of the USAF Radio Solar Telescope Network (RSTN). It is found that the occurrence rate of type III bursts strongly correlates with solar activity. However, the profiles for the smoothed type III burst occurrence rate differ considerably from those for the sunspot number, 10.7 cm solar radio flux, and solar flare index. The type III burst occurrence rate (T3BOR) is proposed as a new index of solar activity. T3BOR provides complementary information about solar activity and should be useful in different studies including solar cycle predictions and searches for different periodicities in solar activity. This index can be estimated from daily results of the Automated Radio Burst Identification System. Access to data from other RSTN sites will allow processing 24 hr radio spectra in near-real time and estimating true daily values of this index. It is also shown that coronal type III bursts can even occur when there are no visible sunspots on the Sun. However, no evidence is found that the bursts are not associated with active regions. It is also concluded that the type III burst productivity of active regions exhibits solar cycle variations.
- OSTI ID:
- 21562517
- Journal Information:
- Astrophysical Journal Letters, Vol. 736, Issue 1; Other Information: DOI: 10.1088/2041-8205/736/1/L20; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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