As a couple of times before, we will use multiplot to align the various figures. Here is the code
reset set palette rgbformulae 33, 13, 10 set cbrange [-0.3:1] a=-0.1 b=0.13 set multiplot unset ztics unset xtics unset ytics set size 1.1, 0.5 set samples 100,100 set isosamples 100, 100 set origin 0,a set border 0 unset colorbox unset key set view 55,30 set xlabel 'x' set ylabel 'y' sp besj0(x*x+y*y) w pm3d at b unset xlabel unset ylabel set origin 0,a+b sp besj0(x*x/1.2+y*y/1.2)/1.2 w pm3d at b set origin 0,a+2*b sp besj0(x*x/1.4+y*y/1.4)/1.4 w pm3d at b set origin 0,a+3*b sp besj0(x*x/1.65+y*y/1.65)/1.65 w pm3d at b set origin 0,a+4*b sp besj0(x*x/1.95+y*y/1.95)/1.95 w pm3d at b set origin 0,a+5*b set arrow 1 from screen 0.1, 0.1 to screen 0.1, 0.8 set label 1 "time" at screen 0.08, 0.45 centre rotate by 90 sp besj0(x*x/2.2+y*y/2.2)/2.2 w pm3d at b unset multiplot
And here is the figure that it produces
As you can see, as time goes on, the waves move radially outwards. (You shouldn't be carried away by the exact time evolution. This is only a demonstration:) Basically, we plot the functions on maps, and each time we translate the position of the new plot.