Fig. 3
From: A candidate secular variation model for IGRF-12 based on Swarm data and inverse geodynamo modelling
Core-flow estimate. a Core-flow estimate at Earth’s core surface for epoch 2014.3. The gray scale map is that of the toroidal velocity scalar, which measures the amount of local rotation. b The cylindrical radial component of our preferred estimate of the flow inside Earth’s core at the same epoch. Isosurfaces corresponding to +12 km/year and −12 km/year in red and blue, respectively. We are facing the Greenwich meridian (materialized by the black segment in the equatorial plane). The arrow points through the North Pole. These flow estimates are obtained using an inflation factor β=95.7 and are truncated at spherical harmonic degree and order 30 (see text for details)