Numerical examples of the SSGT h_ipq(r_R, t; r_Q), with both r_Q and r_R on the equator and r_R positioned to the east of r_Q. r_Q is located on the surface. All time-series have been filtered by a four-pole Butterworth bandpass filter with corner frequencies at 0.002–0.08 Hz and are plotted with the same vertical scale. Only elements with significant amplitudes are plotted.