time	zsurf	v
  975600.000	      -0.051	       0.004
  979200.000	      -0.070	       0.005
  982800.000	      -0.079	       0.003
  986400.000	      -0.063	       0.004
  990000.000	      -0.026	       0.004
  993600.000	      -0.017	       0.004