[Wrf-users] Doubt regarding Wind speed measurement in WRF-ARW model output

[Eric Altshuler]

Dipak,

For WRF state variables such as winds, the output is for a particular instant in time (or more precisely, the values of the wind components following the integration of the model over the most recent time step). They are not averaged over any specific time period, unlike some flux variables such as radiative and heat fluxes which may be averaged over a certain time interval (e.g. the history interval).

Check the units of your observational data and be sure they are the same as the WRF wind units (m/s), and if the obs winds are in different units, convert them to m/s.

Best regards,

Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793

----- Original Message -----
From: "dipak sahu" <dipakmath at gmail.com>
To: wrfhelp at wrf-model.org, wrf-users at ucar.edu
Sent: Saturday, May 15, 2010 3:21:33 PM
Subject: [Wrf-users] Doubt regarding Wind speed measurement in WRF-ARW model output

Dear sir
I've one doubt regarding wind speed calculation in WRF-ARW model output
by using GrADS. I'm using WRF-ARW model since last 2-3yrs for my PhD
pupose. Always it one doubt in my mind regading the calculation of wind
speed and wind direction in model output through GrADS.
1- Suppose history interval was set in my model run as 1hr,and after
postprocessing i want to know the wind speed at t=12th hour of forecast.
So how it gives the value? Is it gives the instant wind speed value at
that time or the average wind speed of some past time? Because after my
model comparison with observation , I found that the observation wind
speed and model wind speed has a huge gap.

with regards

Dipak


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