No, that's not it. The tl_Hz here needs to be changed to ad_Hz.
The TS_MPDATA is partially coded and untested. We have not coded the tangent linear and adjoint versions of mpdata_adiff routine. We had rewritten the MPDATA algorithm in ROMS several times because we were not fully satisfied with its implementation. So there is not point to build a tangent linear and adjoint codes of an algorithm that is still under testing. It is a wait of time.
The tangent linear and adjoint linearization of the MPDATA algorithm is not trivial. MPDATA, as implemented, is highly nonlinear and we don't know if the tangent linear approximation will hold. The adjoint is a sensitivity operator and it is likely that the TLM, RPM, and ADM will go unstable.
Therefore, we currently do not support the tangent linear, representer, and adjoint for this option.
