Large-scale patterns and ‘active longitudes’

Connection between Active Longitudes and Magnetic Helicity

A two-dimensional mean field dynamo model is solved where magnetic helicity conservation is fully included. The model has a negative radial velocity gradient giving rise to equatorward migration of magnetic activity patterns. In addition the model develops longitudinal variability with activity patches travelling in longitude. These patches may be associated with active longitudes.

Active longitudes, nonaxisymmetric dynamos and phase mixing

We discuss the problem of solar active longitudes from the viewpoint of dynamo theory. We start from a recent observational analysis of the problem undertaken by Berdyugina & Usoskin (2003, A&A, 405, 1121) and Usoskin et al. (2005, A&A, 441, 347) who demonstrated from a study of sunspot data that solar active longitudes rotate differentially, with a small but significant asynchrony between nort...

Comoving frames and active longitudes: Does the Sun have face?

Context. Using Greenwich sunspot data for 120 years it was recently observed that activity regions on the Sun’s surface tend to lie along smoothly changing longitude strips 180◦apart from each other. After critique of the original paper, the new arguments were found to substantiate the claim. Aims. In this paper we analyse new arguments in some detail. Methods. To check basic arguments about pe...

Large-scale temporal and spatial patterns

Phytoplankton constitute the main algal biomass in pelagic ecosystems and, therefore, play a fundamental role in the functioning of the marine trophic web. Information on long-term trends in marine phytoplankton may help to distinguish between biological responses to natural oscillations in climate and global warming, and to evaluate possible regional effects of eutrophication. The aim of this ...

Large-scale atmospheric circulation patterns associated with the occurrence of severe storms Zab basin