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Re: [ferret_users] regriding of variable by using lat lon as a variable


When you say longitude[J=@1:'npts'], you have an extra @ sign. I think you mean J=1:`npts`.  Also, make sure you are using the grave-accent surrounding the `npts`, not single-quotes.


On 11/29/2016 4:00 AM, Yogesh Tiwari wrote:
Hi Ansley,


I tried to grid data variable using ferret link you forwarded, but there is an error in LOC transformation: 

 ! FERRET v6.95
 ! Linux 2.6.32-573.7.1.el6.x86_64 64-bit - 10/27/15
 ! 29-Nov-16 16:44

use ESACCI-GHG-L2-CH4-SCIAMACHY-WFMD-20111231-fv1.nc
sh d
     currently SET data sets:
    1> ./ESACCI-GHG-L2-CH4-SCIAMACHY-WFMD-20111231-fv1.nc  (default)
 name     title                             I         J         K         L         M         N
 TIME     time                            ...       1:1755    ...       ...       ...       ...
 LATITUDE latitude                  ...       1:1755    ...       ...       ...       ...
 LONGITUDE   longitude         ...       1:1755    ...       ...       ...       ...
 XCH4     column-averaged dry air mole fr  ...       1:1755    ...       ...       ...       ...

let xdif=longitude[J=@DDF]
let xcross=xdif[J=@EVNT:0]
list longitude, xdif, xcross
             DATA SET: ./ESACCI-GHG-L2-CH4-SCIAMACHY-WFMD-20111231-fv1.nc
             Y: 0.5 to 1755.5
 Column  1: LONGITUDE is longitude (degree_east)
 Column  2: XDIF is LONGITUDE[J=@DDF]
 Column  3: XCROSS is XDIF[J=@EVNT:0]
1      /    1:   144.1    0.5    0.0
2      /    2:   144.6   -0.5    1.0
3      /    3:   144.1    0.5    2.0
4      /    4:   144.5   -0.5    3.0

let npts = 'xcross[J=@LOC:1]'
define axis/x/units=degrees_east xaxis=longitude[J=@1:'npts']
 **ERROR: command syntax: Unknown transformation:J=@1:'npts'
          Use SHOW TRANSFORMS for a list of legal transformations

On Mon, Nov 28, 2016 at 11:23 PM, Ansley C. Manke <ansley.b.manke@xxxxxxxx> wrote:


Do the "lat" and "lon" variables represent a grid?  If so, then you need to define X and Y axes which correspond to the lon/lat data.  This FAQ, http://ferret.pmel.noaa.gov/Ferret/faq/reading-ascii-data-representing-a-grid, though it discusses reading ASCII data, shows an example of defining axes using what is in lists of  lat/lon values.  Once you have defined the X-Y grid, then you'd use RESHAPE to put your data onto that grid.  Pay attention to whether your data lists longitude varying fastest.

If the "lat" and "lon" variables represent scattered data, then you would define use one of the SCAT2GRID functions.  To see a list of the options, type

yes? show function scat2grid*xy


On 11/25/2016 2:07 AM, 'Yogesh Tiwari' via _OAR PMEL Ferret Users wrote:
Dear Ferret Users,

I am using ferret v 6.95 on Linux OS

I have a netcdf file with three different variables as "v1". "lat", "lon" on J-axis
How to regrid "v1" on i-axis & j-axis using "lat" and "lon". Data looks like below:

  FERRET v6.95  
  Linux 2.6.32-573.7.1.el6.x86_64 64-bit - 10/27/15
  25-Nov-16 15:25     

yes? use data.nc
yes? sh d
     currently SET data sets:
    1> ./data.nc  (default)
 name     title                             I         J         K         L         M         N
 v1            var                        ...       1:1869    ...       ...       ...       ...
lat             latitude                  ...       1:1869    ...       ...       ...       ...
lon            longitude               ...       1:1869    ...       ...       ...       ...



Yogesh K. Tiwari (Dr.rer.nat),
Centre for Climate Change Research,
Indian Institute of Tropical Meteorology,
Homi Bhabha Road,

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