[Fwd: Re: Reliable ETA80 Grib data containing dewpoint data]

[Sestak, Dr. Michael]

The formula probably only includes the saturation vapor pressure over water.
For upper levels (and anywhere with air temperature below 0 C, you probably
need a conversion that includes saturation vapor pressure over ice.  I don't
have it at my fingertips, but any good atmospheric physics book should cover
this.

-----Original Message-----
From: Daniel Leins [mailto:Daniel.Leins at NOAA.GOV]
Sent: Friday, April 15, 2005 10:45 AM
To: GRADSUSR at LIST.CINECA.IT
Subject: [Fwd: Re: Reliable ETA80 Grib data containing dewpoint data]


------List,

Yeah, I discovered that formula is useless once you get up into the
midlevels of the atmosphere.  I plotted actual dewpoint at 500 on top of
my calculated dewpoint at 500, and there was about a 10ºC difference,
where the calculated dpt was cooler than the actual.  Back to looking
for full blown grib data I guess...Anyone have any ideas?

Dan



Matt Alonso wrote:

> Hey Dan, I use the NAM 212 (nam.t**z.awip3d**.tm00) from the NCEP ftp
> site and it has relative humidity on all of the layers in the data
> file.  Give those a try.  Let me know how this works out for you.
> Regards, Matt