Re: [ferret_users] grid interpolation

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

Hi Estanislao,

Oh, I see.  Curvilinear grids are not integrated as closely into ferret/PyFerret as rectilinear grids are.  Please see this documentation about curvilinear grids for details about graphics and functions that allow you to use these coordinates

https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/working-with-special-data-sets/CURVILINEAR-COORDINATE-DATA

The section has links to the command syntax for graphics commands, and the function calls.

Ansley

On 1/16/2020 9:46 PM, ESTANISLAO GAVILAN PASCUAL-AHU wrote:

Hi Ansley,

thanks so much for your reply. I will take a closer look to the chapter 4. The main problem of my grid is that it is a curvilinear grid. That is the reason of using gx and gy after assigning the grid to each variable. But for some reason it does not do the interpolation.

Kind regards,

Estanislao

-----Original Messages-----
From: "Ansley C. Manke" <ansley.b.manke@xxxxxxxx>
Sent Time: Wednesday, January 15, 2020
To: ferret_users@xxxxxxxx
Cc:
Subject: Re: [ferret_users] grid interpolation

Hi Estanislao,

There are several regridding transformations available.  By default a regridding operation uses linear interpolation, or you can specify @LIN explicitly, or @AVE for regridding using weighted averaging, or @ASN to do the regridding by assignment.  "yes? show transforms" will give you the complete list.  @ASN asks Ferret to simply map the data values onto the requested axis without any interpolation.

Here is the documentation about regridding: 

https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/Grids-Regions/GRIDS#Chapter4-Regridding

cheers, Ansley

On 1/12/2020 10:53 PM, ESTANISLAO GAVILAN PASCUAL-AHU wrote:

Hi community,

I would like to interpolate this data. The sea surface elevation is inside a grid where the points are in the center of the cell. I am trying to get the interpolation to the u and v points which are on the walls of the cell. I used this code but I obtain the same values for the u a v points. Thank in advance for your help

define grid/x=lon/y=lat grid_t

define grid/x=lonu/y=latu/like=velu grid_u

define grid/x=lonv/y=latv/like=velv grid_v

let t_com=etan[g=grid_t@asn]

let u_com=velu[g=grid_u@asn]

let v_com=velv[g=grid_v@asn]

let tcomu=t_com[gx=u_com,gy=u_com]

let tcomv=t_com[gx=v_com,gy=v_com]

Kind regards,

Estanislao