Adjoint source for single component data

[chenglongduan]

Hi,
Many recent seismic data are recorded by nodal arrays, and they are single component with channel code "DPZ". For the kernel simulation in SPECFEM3D, elastic simulation requires three component (X,Y,Z) adjoint source data to be read in by the code.
How can I prepare the adjoint sources for X and Y component, even if they don't exist? My thinking is that I manually create two zero traces (i.e., repeat zero by NSTEP times), input them to pyadjoint, and output them in specfem adjoint source file format. Now I have three component adjoint source data, but only Z-component is the real valid trace.
Just want to make sure I'm doing right and there's no shortcut to do this. Thanks.