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...

We compare the zonal flow pattern in subsurface layers of the Sun with the distribution of surface magnetic features like sunspots and polar faculae. We demonstrate that in the activity belt, the butterfly pattern of sunspots coincides with the fast stream of zonal flows, although part of the sunspot distribution does spill over to the slow stream. At high latitudes, the polar faculae and zonal...

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...

We have observed high-resolution intensity spectra near the Fe i 1564.8 nm line at a single umbral point corresponding to the darkest position in over 900 sunspots from 1998 through 2005. From these data we determine that the maximum sunspot magnetic fields have been decreasing at about 52 G yr . The same data set shows a concurrent increase in the normalized umbral intensity from 0.60 to 0.75 ...

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...

Sunspots are concentrations of magnetic field on the visible solar surface that strongly affect the convective energy transport in their interior and surroundings. The filamentary outer regions (penumbrae) of sunspots show systematic radial outward flows along channels of nearly horizontal magnetic field. These flows were discovered 100 years ago and are present in all fully developed sunspots....

It is proposed that sunspots (and other flux emergence phenomena) originate due to the presence of fluctuating magnetic fields in addition to the regular, mean field in the convection zone. The mean field predicted by dynamo theories is too weak by itself to emerge at the surface of the Sun. However, the same dynamoprocesses that produce themeanfield also produce fluctuating fields. It is sugge...