[Wrf-users] diff in NAM and NARR

Qian Tan qtan at umbc.edu
Mon Sep 14 09:58:28 MDT 2009


Both NAM(12km, 6hour, 40 levels) and NARR(32km, 3hour 30 levels) data on 
NOMADs/NCDC data server are available with few days' delay. (the 'http' 
link is more updated than the 'ftp4u' link).

On Mon, 14 Sep 2009, Feng Liu wrote:

> Hi, Qian
> NAM: North American Model meteorology files have 40km resolution at 3
> hour intervals. All files after Feb 2008 are grib2, and current year
> files are available. (See NCEP Eta/NAM ds609.2)
> NARR: The North American Regional Reanalysis meteorology has 32km
> resolution at 3 hour intervals so it is even more detailed than NAM.
> NARR has no files for the current year. (see NCEP GRIB GDAS ds083.0)
> Good luck.
> Feng
> -----Original Message-----
> From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On
> Behalf Of Qian Tan
> Sent: Friday, September 11, 2009 9:13 AM
> To: wrf-users at ucar.edu
> Subject: [Wrf-users] diff in NAM and NARR
> Dear WRF users,
> Can someone tell me the major difference between NAM and NARR when we
> prepare input to WPS?
> So far what I have found:
> They both cover North America, with similar resolution.
> NAM, reanalysis mode has few months delay, and it has the forecast mode.
> NARR has half month delay, and you need some extra steps to prepare them
> for WPS since not all required fields are there.
> What is other difference? In term of WRF performance, which one is
> better?
> Thanks,
> Qian
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