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Re: [ferret_users] interpolating station data



Hi,

Are the stations all located quite close together in x-y and time?  If so you might consider simply regridding in Z to a common Z axis and averaging the data.  I don't know that only six stations would get you anything meaningful on a longitude/latitude grid.

Here's how the z averaging could work, if it makes sense to look at the profiles as if they are at a common location, using the ENSEMBLE capabilities in Ferret.  This method ignores the different station locations and times.

yes? use station1.nc

! regrid the temperature variable to the grid of the first station. We want to 
! keep the original name, so rename the file variable and define the new one
! using the original name.

yes? use station2.nc
yes? set variable/name=temp_in temperature

! Assign the data to the xyt grid of the data in dataset 1, and do a 
! linear regridding in z.  Assign the attributes such as unis. Now
! temperature has the same grid in dataset 1 and dataset 2.

yes? let/d=2 temperature = temp_in[d=2,gxyt=temperature[d=1]@asn,gz=temperature[d=1]]
yes? set attribute/like=temp_in[d=2] temperature[d=2]

yes? use station3.nc
yes? set variable/name=temp_in temperature
yes? let/d=3 temperature = temp_in[d=3,gxyt=temperature[d=1]@asn,gz=temperature[d=1]]
yes? set attribute/like=temp_in[d=3] temperature[d=3]

yes? use station4.nc
...

! Define the ensemble dataset.  We've only reconciled the grid of temperature, so we
! get a bunch of messages that the other variables aren't included in the ensemble
! Any other variables to include would be handled in the same way before defining
! the ensemble.

yes? ensemble all_stations =  station1.nc, station2.nc, station3.nc, ...

           *** NOTE: Variable "TEMPERATUREFLAG" excluded from aggregate: Z axis differs among members
           *** NOTE: Variable "TEMPERATURE_2" excluded from aggregate: Z axis differs among members
...

! With just two stations, this is how it looks -- see how temperature has a grid of M=1:2
! The ensemble operation defines variables containing the dataset names, and the global attributes
! of the member datasets.


yes? show data all_stations
     currently SET data sets:
    3> all_stations  (default)  Ensemble aggregation
 name     title                             I         J         K         L         M         N
 WOCE_DATE
          WOCE date                        ...       ...       ...       1:1       1:2       ...
 WOCE_TIME
          WOCE time of day                 ...       ...       ...       1:1       1:2       ...
 TEMPERATURE
          Primary Temperature              1:1       1:1       1:3730    1:1       1:2       ...
 ------------------------------
 MEMBER_DSET
          Member dataset names in Ensembl  ...       ...       ...       ...       1:2       ...
 WOCE_VERSION
          Global Att *WOCE_Version* in En  ...       ...       ...       ...       1:2       ...
 CONVENTIONS
          Global Att *Conventions* in Ens  ...       ...       ...       ...       1:2       ...
...


! Then you can do operations on "TEMPERATURE" in the E direction, save them to a dataset, etc
yes? plot temperature[m=@ave]


On 10/28/2018 4:39 PM, saurabh rathore wrote:
Dear ferreters,
G'day

I am having station data of temperature and salinity at six different station and I want to generate a gridded field from this data by using interpolation. So how can i do it ? I am attaching two example files in this email.

cheers, saurabh

--


REGARDS

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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