Re: [ferret_users] how does @DIN work on the pressure coordinate

[Ryo Furue <furue@xxxxxxxxxx>]

Hi Xiaoyu,

On Thu, Sep 5, 2019 at 9:10 AM Karl Smith - NOAA Affiliate <karl.smith@xxxxxxxx> wrote:

`@DIN` is just a numerical integral - multiply the cell width

I might add that you have to tell Ferret the cell widths if they aren't constant.

> How does it give weight to each pressure level?

Basically, you need to tell Ferret the positions of the edges of the cells if the gridspacing is not uniform.

If your data is stored in a netCDF file, the vertical (pressure) coordinate has to have an associated "_bnd" values:  You can read about the "_bnd" values in

    http://cfconventions.org

If your data doesn't provide the positions of the edges, you can manually provide it using the EDGES qualifier of the DEFINE AXIS command

    https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/commands-reference/DEFINE 

Basically, you provide the positions of the edges and ask Ferret to calculate the positions of the cell centers and to assign them to the variable you want to integrate.

Regards,

Ryo