Re: [ferret_users] Ferret unit conversion

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

Hi Krishnapriya,

In short, if the units of the coordinates are in recognized time or location units, which are called "world units" in the documentation, then Ferret will handle units conversion internally, and you do not need to do your own conversion.

The details are discussed in the documentation about Transformations: http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/variables-xpressions/XPRESSIONS#GeneralInfo, and in the DEFINE AXIS/UNITS= documentation.  There is further useful information in the rest of the section about Transformation.

If the units are not recognized, either from the metadata in a netCDF dataset, or on a DEFINE AXIS command, Ferret will issue a note to indicate that.

           *** NOTE: (fyi) units are not subject to auto-conversion: unit_name

-Ansley

On 11/17/2016 8:39 PM, Krishnapriya M wrote:

Hi,

    I would like to know the unit conversions in ferret while doing integration, differentiation and other transformations. I have a vague idea about how ferret is considering the units. First of all my data is in daily format. My variables are v1(in kg) and v2(in kg/s). I want to calculate forward derivative of v1 w.r.t time(v1[T=@DDF]) and v2[x=@sum,y=@sum]. My question is whether it necessary to convert my v1 in terms of seconds before applying transformations also @sum over spatial axes(v2[x=@sum,y=@sum]) makes any changes in its unit..

Could you please help me to sort out this.

Looking forward your reply.
    

With Regards,
Krishnapriya M

Senior Research Fellow,

Ocean Integrated Biogeochemical Modeling Group(OIBM),

National Remote Sensing Centre (ISRO),

Balanagar,

Hyderabad-500037

Ph:040-23884576