Large-scale photospheric motions determined from granule tracking and helioseismology from SDO/HMI data

Context. Large-scale flows in the Sun play an important role in the dynamo process linked to the solar cycle. The important large-scale flows are the differential rotation and the meridional circulation with an amplitude of km s−1 and few m s−1, respectively. These flows also have a cycle-related components, namely the torsional oscillations.Aim. Our attempt is to determine large-scale plasma flows on the solar surface by deriving horizontal flow velocities using the techniques of solar granule tracking, dopplergrams, and time–distance helioseismology.Methods. Coherent structure tracking (CST) and time-distance helioseismology were used to investigate the solar differential rotation and meridional circulation at the solar surface on a 30-day HMI/SDO sequence. The influence of a large sunspot on these large-scale flows with a specific 7-day HMI/SDO sequence has been also studied.Results. The large-scale flows measured by the CST on the solar surface and the same flow determined from the same data with the helioseismology in the first 1 Mm below the surface are in good agreement in amplitude and direction. The torsional waves are also located at the same latitudes with amplitude of the same order. We are able to measure the meridional circulation correctly using the CST method with only 3 days of data and after averaging between ± 15° in longitude.Conclusions. We conclude that the combination of CST and Doppler velocities allows us to detect properly the differential solar rotation and also smaller amplitude flows such as the meridional circulation and torsional waves. The results of our methods are in good agreement with helioseismic measurements.

Some peculiarities in longitude distribution of sunspot groups over last four eleven-year solar cycles

This paper considers a longitude distribution of sunspot groups over 1982–2013, using data from the National Geophysical Data Center (Boulder, USA). The space-time distribution of sunspot groups is analyzed in coordinate sectors calculated from heliographic longitudes of the groups. A longitude extent of a coordinate sector is compared to the average size of one active region (30–40°). Then, in each coordinate sector, evolutionary activity of sunspot groups is summarized according to classification values after Malde throughout the observation period. The longitude distribution of large sunspot groups plotted in such a way does not reveal anticorrelation between Northern and Southern hemispheres in sunspot cycle 23.

Mating success of resident versus non-resident males in a territorial butterfly

Male–male competition over territorial ownership suggests that winning is associated with considerable benefits. In the speckled wood butterfly, Pararge aegeria , males fight over sunspot territories on the forest floor; winners gain sole residency of a sunspot, whereas losers patrol the forest in search of females. It is currently not known whether residents experience greater mating success than non-residents, or whether mating success is contingent on environmental conditions. Here we performed an experiment in which virgin females of P. aegeria were allowed to choose between a resident and a non-resident male in a large enclosure containing one territorial sunspot. Resident males achieved approximately twice as many matings as non-residents, primarily because matings were most often preceded by a female being discovered when flying through a sunspot. There was no evidence that territorial residents were more attractive per se , with females seen to reject them as often as non-residents. Furthermore, in the cases where females were discovered outside of the sunspot, they were just as likely to mate with non-residents as residents. We hypothesize that the proximate advantage of territory ownership is that light conditions in a large sunspot greatly increase the male's ability to detect and intercept passing receptive females.