Correcting Surface Pressure to Sea Level

[Kevin M Levey]

Hi Mark,

If you are plotting from the GFS grib data, then use the mean sea-level pressure variable instead of geopotential height, i.e. 

'define mslp = prmslmsl/100' 

prmslmsl is in Pascals, hence divide by 100 to get hPa (or mb).

Regards,

Kevin M Levey, MSc in Oceans and Atmospheric Sciences (University of Cape Town)
Director of Meteorological Operations
CustomWeather, Inc.
San Francisco, California, USA

"Taking the World by Storm!"

http://www.customweather.com
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email: klevey at customweather.com

On Mar 11, 2010, at 03/11/10 - 12:16 PM, Mark Hess wrote:

> I tried to access the GrADS User archives for this answer, but the page would not allow me to search.Perhaps someone can point me in the right direction.  When plotting surface pressure (isobars)  from the GFS GRIB files, my data show very low pressure values over land.  While not sure, I am guessing this is because the data need to be corrected to sea level.  Is this correct? If so, can someone provide a resource which explains how to 'correct' the data? If I am incorrect, Can you please explain what I am doing wrong? Thanks.
>  
> Mark
>  

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