Sublithospheric Small Scale Convection
Initially, the box has uniform temperature of 1 everywhere. With surface
temperature is fixed at 0 as boundary condition, the box cools with the
time. As the box cools, the top thermal boundary layer thickens with time.
Depending on activation energy and mantle viscosity, the thickened top
thermal boundary layer eventually goes unstable. The panel on the top shows
how surface heat flux evolves with time and how it compares with the cooling
half-space model prediction (in dashed line). The panel on the right shows
how the horizontally averaged temperature vs depth varies with time and it
compares with the cooling half-space model prediction (in dashed line).