Necessary core-mantle boundary heat flux pattern ingredients for observed latitudes of geomagnetic surface intensity minima

Abstract

Thermal core-mantle interactions affect the convection pattern in the outer core and thus the morphology of the generated geomagnetic field.Correlations between longitudes of lowermost mantle seismic anomalies and prominent geomagnetic flux patches (normal and reversed) provideevidence for mantle control on the geodynamo (Gubbins et al., 2007, Terra-Nova et al., 2016). Analyses of geomagnetic field models and numerical dynamos with heterogeneous outer boundary heat flux inferred from lower mantle seismic anomalies demonstrated that the SAA longitudinal preferred position is also mantle controlled (Terra-Nova et al., 2019). In contrast, the present latitude of SAA was seldom reproduced. For fundamental understanging of the type of CMB heat flux pattern that may lead to large latitudes of surface intensity minima, we explore dynamo models with different single harmonic CMB heat flux patterns. Our goal is to unravel the core-mantle interaction that induces recurrent large latitude surface intensity minima. Here we show preliminary results from these simulations.