192 citations · 1.3k across the 41 of their papers we have counts for
4 papers · 1 filter
Limitations of force-free magnetic field extrapolations: revisiting basic assumptions
H. Peter, J. Warnecke, L. P. Chitta +1
Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. The extrapolations assume that the ratio of internal energy…
Multiple dynamo modes as a mechanism for long-term solar activity variations
Maarit J. Käpylä, Petri J. Käpylä, Nigul Olspert +4
Solar magnetic activity shows both smooth secular changes, such as the Grand Modern Maximum, and quite abrupt drops that are denoted as Grand Minima. Direct numerical simulations (…
Influence of a coronal envelope as a free boundary to global convective dynamo simulations
Jörn Warnecke, Petri J. Käpylä, Maarit J. Käpylä +1
We explore the effects of an outer stably stratified coronal envelope on rotating turbulent convection, differential rotation, and large-scale dynamo action in spherical wedge mode…
Bipolar region formation in stratified two-layer turbulence
Jörn Warnecke, Illa R. Losada, Axel Brandenburg +2
This work presents an extensive study of the previously discovered formation of bipolar flux concentrations in a two-layer model. We interpret the formation process in terms of neg…