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Re: [ferret_users] finding maximum value depth




Hi,

You need to make use of the @MAX and @LOC transformations as mentioned here in the user guide.

http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/variables-xpressions/XPRESSIONS#_VPID_174

You subtract the maximum velocity at each time from U and the find the depth at which this new variable is zero.

In your case

let u_max = u_new[z=@max]
let zero_at_max = u_new-u_max
let depth_at_max = zero_at_max[Z=@LOC:0]

(Ansley, this one seems to come up a few times. It's probably worth adding the example to the FAQ Analysis section.)

Cheers,
Russ


On 30/04/14 14:58, chinnu sachi wrote:
Dear ferret users,
                             I had a 48year data file consisting each year's winter season(DJF averge) velocity data with depths.

yes? use djf_avg.nc
yes? sh d/v
     currently SET data sets:
    1> ./djf_avg.nc  (default)
 
 name           title                                                 I         J            K         L
 U_NEW    U[GX=XLON,GY=YLAT]               ...       ...       1:20      1:48
       (X=65E:75E@AV4, Y=2S:2N@AV4)
        on grid GCW1 with -999.999 for missing data
             Z=-0.1569:574.8 
 
  time range: 15-FEB-1960 00:00 to 15-FEB-2007 00:00

yes? list l[g=u_new]
             VARIABLE : L
                        axis TIME
             FILENAME : djf_avg.nc
             SUBSET   : 48 points (TIME)
 FEB-1960 /  1:   1.00
 FEB-1961 /  2:   2.00
 FEB-1962 /  3:   3.00
 FEB-1963 /  4:   4.00
 FEB-1964 /  5:   5.00
 FEB-1965 /  6:   6.00
 FEB-1966 /  7:   7.00
 FEB-1967 /  8:   8.00
 FEB-1968 /  9:   9.00
 FEB-1969 / 10:  10.00
 FEB-1970 / 11:  11.00
 FEB-1971 / 12:  12.00

Now I want to find out the maximum velocity depth in each year's winter season.

Thanks in advance.

Regards,
Chinnu Sachidanandan
Physical Oceanography Division
National Institute of Oceanography
csachidanandan@xxxxxxx



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