Adaptive meshing in FD solver

Hello all,

If any one knows how the adaptive meshing is working in FD solver?
U can see in picture the first mesh was 0.4 M tetrahedrons was used. Later after adaptive meshing it increased to 1M.
I understand that the mesh accuracy will be increased in adaptive meshing. But here the mesh on the ground surface is increased.
Is there any option to reduce the mesh on ground and increase the mesh on the traces, discrete ports of the FD solver?