Re: vinth2p with CMIP data

oops! ... surface pressure (ps) is LESS THAN the
           constant pressure level ...

On 3/27/12 1:19 PM, Dennis Shea wrote:
> [1] If you are interpolating from hybrid to pressure levels,
> any grid point where the surface pressure (ps) is greater than the
> constant pressure level is below ground. (ps=791, the 850 is below ground).
>
> [2] Perhaps the GFDL hybrid coefficients are different than
> the ones used in vinth2p. The eqn for the 'a' and 'b' coefficients
> can take slightly different forms.
>
>
>
>
>
> On 3/27/12 12:10 PM, kelly lombardo wrote:
>> I was just interpolating to 850; 700; 500; 300; 200 hPa, nothing below
>> ground level. Could it be that this routine isn't calibrated for GFDL
>> model output, and can only be used with the CESM? I assumed that the A
>> and B coefficients would be alright since it looks like these
>> coefficients in both the GFDL and CESM are used for the middle point in
>> between the model grid levels. Maybe this was an incorrect assumption?
>>
>>
>>
>> ------------------------------------------------------------------------
>> *From:* Dennis Shea<shea@ucar.edu>
>> *To:* kelly lombardo<kellyann7319@yahoo.com>
>> *Cc:* "ncl-talk@ucar.edu"<ncl-talk@ucar.edu>
>> *Sent:* Tuesday, March 27, 2012 1:50 PM
>> *Subject:* Re: [ncl-talk] vinth2p with CMIP data
>>
>> If you are interpolating, there should be no winds that
>> look "too strong". If you are extrapolating (below ground level)
>> then this could be the case. vinth2p_ecmwf will extrapolate
>> temperature (using the lapse rate) and/or geopotential (lapse
>> rate and hydrostatic formula). *All* other variables are
>> set to the the nearest non-missing value. This could result
>> in "too strong" winds.
>>
>> As noted in the documentation, the vinth2p was taken directly
>> from the old model processor. NCL changed nothing.
>>
>> My suggestions:
>> (1) do not extrapolate [*all* extrapolations not guided
>> by physics are dangerous, even then use with caution]
>>
>> (2) Look at "Grid Fill" examples at
>> http://www.ncl.ucar.edu/Applications/grid_fill.shtml
>> In particular the ones using 'poisson_grid_fill'
>> Good Luck
>>
>> On 03/27/2012 11:27 AM, kelly lombardo wrote:
>> > Hey everyone
>> >
>> > I am trying to interpolate CMIP GFDL-ESM2M data (such as U, V, T) which
>> > is stored on hybrid sigma-pressure coordinates to pressure coordinates
>> > using vinth2p. I was able to interpolate the data, but the winds look
>> > too strong. Has anyone encountered a similar problem? Or does anyone
>> > know where I can find the vinth2p code so I can see how the
>> > interpolation is calculated?
>> >
>> > Thanks
>> > kelly
>> >
>> >
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>>
>>
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Received on Tue Mar 27 13:22:45 2012