9:00 AM - 9:15 AM
[S17-1-02] Erosion of a thermally induced stably stratified layer by compositional convection in the Earth's outer core
We propose to use radial distribution of power induced by thermal and compositional buoyancy (rate of kinetic energy production) as measure of occurrence of thermal and compositional convection.The power consists of the terms proportional to heat flux and compositional flux. The region with positive power is considered that convection is active there because kinetic energy can be produced by buoyancy force. On the other hand, in the region with negative power convection is suppressed and stably stratified layer may be produced.
We constructed a 1-dimensional thermal and compositional balance model of the Earth's core with the updated values of thermal conductivity under conditions of planetary cores derived by recent high-pressure experiments and first principle calculations, and obtained radial distributions of power for various values of the core-mantle boundary (CMB) heat flux Q. When Q > 9.3 TW, it is suggested that convection occurs in the whole outer core, however, a stable layer with O(100km) thickness could be produced below CMB when Q < 4.8 TW. Our result is in contrast with the previous studies on the assumption that the region with negative heat flux is stably stratified, where a stable layer whose thickness of O(1000km) could be produced when the heat flux across CMB is small.
We constructed a 1-dimensional thermal and compositional balance model of the Earth's core with the updated values of thermal conductivity under conditions of planetary cores derived by recent high-pressure experiments and first principle calculations, and obtained radial distributions of power for various values of the core-mantle boundary (CMB) heat flux Q. When Q > 9.3 TW, it is suggested that convection occurs in the whole outer core, however, a stable layer with O(100km) thickness could be produced below CMB when Q < 4.8 TW. Our result is in contrast with the previous studies on the assumption that the region with negative heat flux is stably stratified, where a stable layer whose thickness of O(1000km) could be produced when the heat flux across CMB is small.