[gradsusr] Lapse Rates

[Daniel Nairn]

Thanks Jeff, I wasn't convinced that my original formula was going to be
that accurate.  I've updated my script, as you suggested, for the 700-500
lapse rates however the images generated are now blank? The script
completes without any errors. If I revert back to my original script then
the images are produced as expected.



On 13 November 2014 22:59, Jeff Duda <jeffduda319 at gmail.com> wrote:

> 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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>
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