tokens: a new set of young solar-type stars. See etal. ( 2015 ) analysed the magnetic field topologies of 55 stars with masses in the range 0.11.5M and discovered that the toroidal field scales with the inverse Rossby number more steeply than the poloidal field does. The toroidal field fraction shows two different power-law dependences on the poloidal field for stars above and below 0.5M . Additionally, they found that strong toroidal fields are typically axisymmetric. To set highly resolved solar or simulated magnetic vector maps into the context of ZDI-observed cool stars, Vidotto ( 2016 ) presented a magnetic field decomposition method. The method is compatible to the description used in ZDI studies and decomposes the magnetic field into spherical harmonics of different -modes up to a maximum max . The small -modes describe the large-scale field ( 1 dipolar, 2 quadrupolar mode, etc.) and the higher -modes the small-scale field. This small-scale field can be removed from the simulations or solar observations by selecting low -modes to compare their magnetic field topology with the magnetic field topology of observed stars. In this Letter, we compare the global time-dependent non-potential simulations of Gibb etal. ( 2016 ) based on the surface flux transport model, with the sample of observed stars 1 analysed by See etal. ( 2015 ). In particular, we compare their magnetic field topologies, focusing on the poloidal, toroidal, and their axisymmetric components at different spatial scales. 2 SIMULATIONS AND METHODS The simulations of Gibb etal. ( 2016 ) used a magnetic flux transport model for the photospheric evolution, coupled with a non-potential coronal evolution model described by a magnetofrictional technique. The magnetic flux transport model solves the magnetohydrodynamic induction equation to evolve the surface magnetic flux, whilst a flux emergence pattern, e.g. bipolar starspot pairs, are advectively injected, and then sheared by surface DR, poleward meridional flow, and diffusion (Charbonneau 2014 ). The flux emergence pattern is based on Yeates ( 2014 ) who determined flux emergence properties using solar synoptic magnetograms observed by the US National Solar Observatory, Kitt Peak, between 2010 January and 2011 January. Gibb etal. ( 2016 ) then varied the flux ER using a statistical model, and the DR in the range of 1 ER/ER 5 and 1 DR/DR 5. The variation of the parameters leads us to 17 simulations ranging from solar-like stars up to stars with five times solar flux ER and DR. The immense difference in resolution prevents a direct comparison between the highly resolved simulated and the relatively poorly resolved observed stellar magnetic field vector maps. Vidotto ( 2016 ) presented a method to filter out the small-scale field from highly resolved solar magnetic field vector maps to ease the comparison with stellar magnetic field vector maps. The method decomposes the radial, azimuthal, and meridional magnetic field components into
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