We analyzed multi-wavelength observations of three surges with a recurrent period of about 70 min in H α , EUV, and soft X-ray, which occurred in the quiet-sun region on 2000 November 3. These homologous surges were associated with small flares at the same base, but their exact footpoints were spatially separated from the flare. Each surge consisted of a cool H α component and a hot, EUV or soft X-ray component, which showed different evolutions not only in space but also in time. The EUV jets had slightly converging shapes, underwent more complicate development, showed clearly twisting structures, and appeared to open to space. The H α surges, however, were smaller and only traced the edges of the jets. They always occurred later than the jets but had dark EUV counterparts appearing in the bright jets. These surge activities were closely associated with two emerging bipoles and their driven flux cancellations at the base region, and were consistent with the magnetic reconnection surge model. The possible cause of the delay between the surges and jets, of the dark structures in the jets are discussed, along with the possible role of flux cancellations in generation of these surges.

Abstract. In the present work, the dominant hemisphere of solar activity in each of solar cycles 12 to 22 has been clarified by calculating the actual probability of the hemispheric distribution of several solar activity phenomena using long-term observational records. An attempt is made to demonstrate that a long characteristic time scale, about 12-cycle length, is inferred to occur in solar activity.

Using sunspot groups and sunspot areas from May 1996 to February 2007, we find that solar activity for cycle 23 is dominant in the southern hemisphere, and our results enhance the inferred but uncertain conclusions obtained before. They are as follows: (1) each four cycles, the slope of the fitting straight lines of north‐south asymmetry values changes its sign, and (2) the asymmetry signs of solar activity at both the low (>0° − <10°) and high (≥25° − ≤90°) latitudinal bands are always the same but sometimes differ at the middle latitudinal band (≥10° − <25°). When the former two are the same as the latter, solar activity is asymmetrically distributed in the hemispheres but symmetrically distributed when the former two differ from the latter. Moreover, asymmetry values of solar activity for the whole disk are always located between the first two and the latter and seem to be the averages of the first two and the latter, suggesting that the asymmetry of solar activity may be a function of latitude. In the forthcoming cycle 24, asymmetry of solar activity is inferred as being similar to cycle 12, and solar activity should remain dominant in the southern hemisphere.

Recently, Chandra and Vats have obtained the yearly period length of the solar coronal rotation cycle by analysing the daily adjusted solar radio flux at the 10.7‐cm wavelength for the years 1947–2009. In this paper, we use the time series (series I) of the yearly period length to investigate the long‐term variation of the rotation of radio emission corona, and we find a weak decreasing trend in the time series. We use the empirical mode decomposition to decompose both the yearly mean value (series II) of the solar radio flux at the 10.7‐cm wavelength and series I into different periodical components. There is a secular trend for each of the two series, and we find a negative correlation in the two trends. The decomposed 11‐yr‐cycle components of the two series show different and complicated periods and there is a phase relation between them. We investigate the cycle‐related variation of the coronal rotation length, and we find that there is no Schwable cycle of statistical significance for the long‐term variation of the rotation cycle length.

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