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Re: [ferret_users] replace data by inserting climatology

Hi Saurabh

This can be done with the "masking" capability.

Take the example in the FAQ on climatologies.

Simplifying some of the syntax in that example - define a climatology. Then go on to define a variable which replaces some values of the file variable with that climatology.

! open a dataset and define the climatology
yes? SET DATA monthly_navy_winds
yes?  LET uwnd_climatology = uwnd[GT=month_reg@MOD]

! Plot the data and the climatology together.
! Using /VLIM will make it easier to compare this plot with the next one.

yes? set view upper
yes? PLOT/X=180/Y=40/T=15-jan-1983:15-jan-1991/vlim=-6:16 uwnd
yes? PLOT/OVER/X=180/Y=40/T=15-jan-1983:15-jan-1991 uwnd_climatology

! Now define the new variable with some values of unwd replaced by the climatology.
! Plot the original variable, then overlay the new one.

yes? let uwnd_replace = if uwnd gt 8 then uwnd_climatology else uwnd
yes? set view lower
yes? PLOT/X=180/Y=40/T=15-jan-1983:15-jan-1991/vlim=-6:16 uwnd
yes? PLOT/OVER/X=180/Y=40/T=15-jan-1983:15-jan-1991 uwnd_replace
(you'll see some NOTEs about ambiguous coordinates when the 'replace' variable is computed. This is fine.)

So the only thing left is for you to find a way to define a "mask" variable which is on the time axis of SST, and has the value of say, 1 at the times when you want to keep the SST time series data, and 0 when you want to make the replacement.

   yes? let replace_var = if mask eq 1 then SST[d=1] else TEMP_CLI[d=2]


On 6/30/2016 7:31 AM, saurabh rathore wrote:
Dear Ferreters,

i am facing a problem in replacing some particular time steps data with the Climatological data of the same months.
for example i am having SST data from 1901-2014 in which i want to replace September, October, November and December of 1997 and January, February of 1998 from the climatological values of the same months i.e. Sep-1997 by Sept-Climatological value, Oct-1997 by Oct-Climatological value and so on.

this is my data description

SST data 1901-2014
 name     title                                                I         J         K         L           M         N
 SST      sea surface temperature (degc)    1:360     1:180     ...      1:1368    ...         ...

  name                                          title                             I             J         K         L         M         N
 TEMP_CLI NINO1[GT=MONTH_GREGORIAN@MOD]    1:360     1:180     ...       1:12      ...       ...

i hope i made my problem clear and i believe i will get the solution.
regards, saurabh



Saurabh Rathore
Research Scholar (PhD.)
Centre For Oceans, Rivers, Atmosphere & Land Science Technology
Indian Institute Of Technology, Kharagpur
contact :- 91- 8345984434

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