BSUM

The median mix is an estimate of the down-going wave in this example. When subtracted from the total wave-field data, the result should be up-going waves. See Figure 88 (B) .

  bsum    infile1   infile2   scalef   
     infile1  =  first  input file name
     infile2  =  second input file name
     scalef   =  scale factor
     output = input1 + scalef*input2

The up-going wave field estimate is then shifted back to 1-way time. Then the data are shifted again by the direct wave down-going times (this time without any bulk shift, to adjust the data to 2-way time. The reflections should be flattened in 2-way time (see Figure 89).

**Figure 88:** BMED: (A) median mix of the direct wave (see figure 87 B) (B) BSUM: direct down-going wave estimate subtracted from total wave field.
$\includegraphics[scale=.8]{Figurebmed.pdf}$

**Figure 89:** BSHF: (A) median mix of the direct wave (see figure 87 B) (B) BSUM: direct down-going wave estimate subtracted from total wave field. Data in 2-way time.
$\includegraphics[scale=.9]{Figurebsum.pdf}$