2018/04/07 by N. Gopalswamy, P. Mäkelä, P. Makela +2 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Atmospheric sciences #Brightness #Brightness temperature #Coronal mass ejection #Latitude #Magnetic field #Microwave #Microwave imaging #Physics #Polar #Solar and Space Plasma Dynamics #Solar cycle #Solar cycle 24 #Solar minimum #Solar prominence #Solar wind #Stellar, planetary, and galactic studies #Sunspot #astro-ph.SR
paper · pdf · doi:10.1016/j.jastp.2018.04.005
21 pages, 10 figures, 1 table, accepted for publication on April 07, 2018 in Journal of Atmospheric and Solar-Terrestrial Physics
arxiv created 2018/04/07 · openalex publication_date 2018/04/23 · arxiv updated 2018/08/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar magnetic field and the active-regions, respectively. We also use the location of prominence eruptions as a proxy to the filament locations as a function of time. We show that the polar microwave brightness temperature is highly correlated with the polar magnetic field strength and the fast solar wind speed. We also show that the polar microwave brightness at one cycle is correlated with the low latitude brightness with a lag of about half a solar cycle. We use this correlation to predict the strength of the solar cycle: the smoothed sunspot numbers in the southern and northern hemispheres can be predicted as 89 and 59, respectively. These values indicate that cycle 25 will not be too different from cycle 24 in its strength. We also combined the rush to the pole data from Nobeyama prominences with historical data going back to 1860 to study the north-south asymmetry of sign reversal at solar poles. We find that the reversal asymmetry has a quasi-periodicity of 3-5 cycles.