mixed layer depth from 3D ocean temperature

[ramesh <kv_ramesh@xxxxxxxxxxxxxx>]

Dear ferret users,

       I  copied the mixid layer depth script
from mail archives.  I  tried to calculate the
mixed layer depth. But it writes all values as undefined.

the script  is as follows:
USE ptemp5801.nc
show data
     currently SET data sets:
    1> ./ptemp5801.nc  (default)
 name     title                             I         J
K         L
 PTEMP    Potential Temperature            1:192     1:128     1:32
1:528
let diff = ptemp - ptemp[k=1] + 0.5
let mld = diff[z=@loc:0]
set r/i=1:192/j=1:128/k=1/l=1:528
save/file=mixlay5801.nc mld


please help me in finding the mixed layer depth.


Ramesh


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