[gradsusr] Lapse Rates

[Jeff Duda]

It would be more accurate if you used the actual height fields at the
pressure levels instead of assuming a fixed height difference.  In other
words, try

'define LR75 = (tmpprs(lev=500)-tmpprs(lev=700)) /
(hgtprs(lev=500)-hgtprs(lev=700)'

for 700-500 mb lapse rates. Note how I flipped the order of the subtraction
from your formula. You'll want to use delta_T = T_upper - T_lower when
computing lapse rates.

0-3 km lapse rates can be difficult if you only have isobaric fields. There
are scripts in the script library to interpolate isobaric fields to
constant height fields. If you don't need high accuracy, subbing in a
pressure level that is close to 3 km works. Depending on the time of year,
usually 700 mb is pretty close, but keep in mind that people usually use
0-3 km ABOVE GROUND LEVEL lapse rates, so in areas of high elevation, 700
mb will be far less than 3 km above ground.

Jeff Duda

On Thu, Nov 13, 2014 at 3:53 PM, Daniel Nairn <dannairn at gmail.com> wrote:

> Hi
>
> Could somebody please help verify my two GrAds scripts for displaying
> Lapse Rates? I have created two individual scripts, one for displaying
> 700-500mb lapse rates and the other for displaying 0-3km lapse rates, they
> are as follows:-
>
> 0-3 Script
> 'define temp = ((tmpprs(lev=1000)-tmpprs(lev=700))/2.5908)'
>
> 700-500 Script
> 'define temp = ((tmpprs(lev=700)-tmpprs(lev=500))/2.5908)'
>
> They work and seem to verify against other sources but they have been
> pieced together form many Google searches and I'm a little unsure if they
> are accurate/correct :-)
>
> Thank you
>
>
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>


-- 
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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