Re: [ferret_users] problem with scat2gridgauss_zt

["Ansley C. Manke" <ansley.b.manke@xxxxxxxx>]

Hi,

Unfortunately some of these functions are not documented. The function expects the third argument, in this case theta, to be on a Z or T axis.  This would allow you to have, for instance, a whole XY grid of data at each Z and T scattered point, and the ZT gridding would result in a gridded variable in XYZT.

If you change your script so that theta is in the z direction, it will work:

set data/ez/columns=3/variables="time,pres,theta" /home/users/ansley/tarfiles/trial.dat
define axis/t=1:4:1 tax
define axis/z=100:1000:50 zax
let thetaz = zsequence(theta)
let theta_grd=scat2gridgauss_zt(pres,time,thetaz,z[gz=zax],t[gt=tax],1,1,1,0)

The SHOW FUNCTION/DETAILS output is one way to find out how the grids of the arguments are used by functions:

yes? show function/details scat2gridgauss_zt
SCAT2GRIDGAUSS_ZT(ZPTS,TPTS,F,ZAXPTS,TAXPTS,ZSCALE,TSCALE,CUTOFF,0)
    Use Gaussian weighting to grid scattered data to a ZT grid.
        Axes of result:
          X: inherited from argument(s)
          Y: inherited from argument(s)
          Z: inherited from argument(s)
          T: inherited from argument(s)
          E: inherited from argument(s)
          F: inherited from argument(s)
    ZPTS: Z coordinates of scattered ZT locations (FLOAT)
        Influence on output axes:
          X: no influence (indicate argument limits with "[]")
          Y: no influence (indicate argument limits with "[]")
          Z: no influence (indicate argument limits with "[]")
          T: no influence (indicate argument limits with "[]")
          E: no influence (indicate argument limits with "[]")
          F: no influence (indicate argument limits with "[]")
    TPTS: T coordinates of scattered ZT locations (FLOAT)
        Influence on output axes:
          X: no influence (indicate argument limits with "[]")
          Y: no influence (indicate argument limits with "[]")
          Z: no influence (indicate argument limits with "[]")
          T: no influence (indicate argument limits with "[]")
          E: no influence (indicate argument limits with "[]")
          F: no influence (indicate argument limits with "[]")
    F: variable at scattered ZT locations. May also be fcn of X,Y,E,F (FLOAT)
        Influence on output axes:
          X: passed to result grid
          Y: passed to result grid
          Z: no influence (indicate argument limits with "[]")
          T: no influence (indicate argument limits with "[]")
          E: passed to result grid
          F: passed to result grid
...

On 2/22/2017 6:10 AM, priyanka banerjee wrote:

Hi,

I have an ascii file with 3 columns: day, height in millibars and potential temperature. Everyday there are different number of height points at different intervals. I want to grid this data. As a simple example this is what I have done:

set data/ez/columns=3/variables="time,pres,theta" trial.dat
define axis/t=1:4:1 tax
define axis/z=100:1000:50 zax
let theta_grd=scat2gridgauss_zt(pres,time,theta,z[gz=zax],t[gt=tax],1,1,1,0)

When I give fill theta_grd I get the following error:

Bailing out of external function "scat2gridgauss_zt":
    No data in scattered z, t points.  F() data values must be defined on Z or T axis.
 **ERROR: error in external function

I am sending an example data file as an attachment. I am using Ferret version 6.96. I went through the ferret archive but I am not sure what I have missed.

Thanks for any help.

Regards,

Priyanka

---------

Priyanka Banerjee

Project Scientist
Centre for Atmospheric and Oceanic Sciences
Indian Institute of Science
Bangalore, India