We demonstrate that for weak flares the dependence on spottedness can be rather weak. The fact is such occur both in small and large active regions. At same time, powerful of classes M X much more often In energy estimates, mean magnetic field starspots also assumed equal to sunspot umbra. So effective 900 Mx/cm$^2$ sunspots 2000 starspots. Moreover, height storage cannot strictly proportional ...

This analysis was conducted on 31 synoptic stations in Iran. Initially, the Mann-Kendall test was administered in order to analyse the trend of alterations of these two components over time and the results suggest that 16% of the stations show significant relationship with annual precipitation (positive and negative). More stations showed significant relationships between sunspots and minimum a...

The study of solar flares (SF) is significant for a more understanding the nature and dynamics sun as well its impact on space weather. This paper will present new idea by studying monthly activity SFs collecting data SFs, flare index (FI), sunspots number (SSN) period from 1986 to 2019, which represents three cycles 22, 23 24. Extracting averages shows us that southern hemisphere active than n...

Abstract We investigated the probability distributions of sunspot area and magnetic flux by using data from Royal Greenwich Observatory USAF/NOAA. constructed a sample 2995 regions with maximum-development areas ≥500 MSH (millionths solar hemisphere), covering 146.7 yr (1874–2020). The were fitted power-law distribution four two-parameter (tapered-power-law, gamma, lognormal, Weibull distributi...

We report on velocity and magnetic field oscillations observed in sunspots using the MDI instrument onboard SOHO. In addition to the well-known velocity oscillations, the data clearly show highly localised oscillations of the magnetogram signal in different parts of the sunspots. We show that only oscillations of the magnetic field vector can produce the observed magnetogram oscillations, and t...

By endowing his agents with simple forecasting models, or representations, Woodford (1990) found that finite state Markov sunspot equilibria may be stable under learning. We show that common factor representations generalize to all sunspot equilibria the representations used by Woodford (1990). We find that if finite state Markov sunspots are stable under learning then all sunspots are stable u...

Sunspots are known to be strong absorbers of solar oscillation modal power. The most convincing way demonstrate this is done via Fourier-Hankel decomposition (FHD), where the local field separated into in- and outgoing waves, showing reduction in Due Helioseismic Magnetic Imager's high-cadence Doppler measurements, power absorption can investigated at frequencies beyond acoustic cutoff frequenc...

A new robust technique is presented for automated identification of sunspots on full-disk white-light (WL) solar images obtained from SOHO/MDI instrument and Ca II K1 line images from the Meudon Observatory. Edge-detection methods are applied to find sunspot candidates followed by local thresholding using statistical properties of the region around sunspots. Possible initial oversegmentation of...