Fig. 2
From: Investigation of regional variation in core flow models using spherical Slepian functions
Location of the tangent cylinder and tangentially geostrophic ambiguous patches. The tangent cylinder can be described by two caps subtending an angle of \(21^\circ\) at the Earth’s center (red) projecting the inner core to the surface of the core–mantle boundary (green) along the rotation axis. A schematic illustration of the tangentially geostrophic ambiguous patches is also shown in blue