Necessary Core‐Mantle Boundary Heat Flux Patterns for Recovering the Latitude of the South Atlantic Anomaly

Abstract The present‐day geomagnetic field at Earth's surface is characterized by an anomalously weak region known as the South Atlantic Anomaly (SAA). Numerical dynamo simulations with an imposed outer boundary heat flux pattern inferred from lowermost mantle seismic anomalies reproduce well the longitude of the SAA, but the latitudes of the modeled surface intensity minima are significantly lower than the observed (Terra‐Nova et al., 2019, https://doi.org/10.1093/gji/ggy519 ). Here we explore numerical dynamos with a variety of large‐scale synthetic patterns of outer boundary heat flux in order to gain fundamental insight into what patterns may yield large latitudes of surface intensity minima. We find that equatorially anti‐symmetric heat flux patterns are required in order to produce large latitudes of surface intensity minima. However, these dynamo models often reverse and their dipole dominance is lost. This trade‐off between dipole‐dominated models with low latitudes of surface intensity minima as opposed to multipolar models with large latitudes of surface intensity minima is also evident upon increase in the strength of the convection vigor. Snapshots of dynamo models that satisfy the geomagnetic observations in terms of both large latitudes of surface intensity minima as well as large dipolarity exist, but are rare. We speculate that reconciling these two fundamental geomagnetic constraints may be achieved with a larger amplitude of an equatorially anti‐symmetric outer boundary heat flux combined with a more rapidly rotating dynamo model.