Dear Mai, Mason and Ricardo<br>I really appreciate your help since I'm not familiar with the subject. now i understand the trends in the equation. i had checked out the results in different levels ( including 700mb). but all these values were about the same order ( 10^-3 (m/s) ). I'm using reanalysis data of NCEP from the following link:<br>
<br><a href="http://dss.ucar.edu/pub/cfsr.html">html</a><a href="http://dss.ucar.edu/pub/cfsr.html">http://dss.ucar.edu/pub/cfsr.html</a><br><br>I'm trying to use this data to compute vertical velocities of air which affect the airplanes passing through these air parcels. (I don't think values below 1 (m/s) have any effects on airliners) . but it seems either I used a wrong datasets which cannot simulate reality conditions or these downwash and upwash streams are local and rapid changes which can't be found in any datasets! <br>
Regards,<br>Alireza<br><br><br><div class="gmail_quote">On Wed, Nov 16, 2011 at 4:51 AM, Ricardo Hallak <span dir="ltr"><<a href="mailto:hallak@model.iag.usp.br" target="_blank">hallak@model.iag.usp.br</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#ffffff">
Hi Alireza,
<br>
<br>next to surface, where the air density (rho) is about 1.2 kg/m^3, a w=1 m/s gives omg=11.8 Pa/s.
<br>In your example, your omg~0.1 Pa/s, so it is a low value. In large-scale, the vertical motion is actually low.
<br>
<br>In thunderstorms (and clusters of thunderstorms as well, which are mesoscale in temporal and spatial range), however, w can frequently be > 20 m/s. If you are dealing with large-scale (synoptic scale) data, your data will not be able to "see" thunderstorms.
<br>
<br>What are the dx and dy intervals of your data? Probably your data can not explicitly resolve big vertical motions. Try to compute w in a region where there is a cold front in activity at, for example, 700 mb level.
<br>
<br>Hope this helps,
<br>Ricardo
<br>
<br><font size="2"><b>On Wed, 16 Nov 2011 04:32:43 +0330, Alireza Azargoun wrote</b>
<br><div><div>> thnx
Tereza
<br>>
<br>> but I don't understand it. did you mean that my
answer [W=0.00912 (m/s)] is not (m/s) and it's in (cm/sec)!? supposing that
isn't a 0.912 cm/sec a low speed vertical velocity airflow!? if there's
any reference on this subject I'll be glad if you anyone notify me about it.
<br>>
<br>> On Wed, Nov 16, 2011 at 4:18 AM, <span dir="ltr"><<a href="mailto:tcavazos@cicese.mx" target="_blank">tcavazos@cicese.mx</a>></span>
wrote:
<br>> <blockquote style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex" class="gmail_quote">
Hi
<br>>
<br>>
The usual unit (magnitude) of vertical velocity is in cm/seg.
<br>>
So, it is fine.
<br>>
<br>>
Cheers,
<br>>
Tereza
<br>>
<br>>
> Dear GrADS users
<br>>
> Hi
<br>>
>
<br>>
> I'm recently working on a project about the vertical speed of air
in
<br>>
> different elevations. I'm using CFSR data in grb2 format. these data
sets
<br>>
> have omega (Pa/s) instead . I tried to convert them to vertical
velocity
<br>>
> (m/s) using this equation:
<br>>
> omega= - rho * g * w ( or omega=- (P/RT) *g * w )
<br>>
> but the results in (m/s ) are in the order of 10^-3. I know it's not
a
<br>>
> Grads problem. but I'm an aerospace student and I need to find out
if
<br>>
> anything is wrong with this equation or the results or not. ( I'm
not
<br>>
> really familiar with meteorology!)
<br>>
>
<br>>
> for example:
<br>>
> if omega= 0.10595
<br>>
> & g=9.807
<br>>
> & R=287
<br>>
> & P= 100000 Pa
<br>>
> & T=294.27
<br>>
> resulted value is W=0.00912 (m/s)
<br>>
>
<br>>
>
<br>>
> Thanks in advance,
<br>>
> Alireza
<br>>
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<br>>
>
<br>>
<span><font color="#888888">
<br>>
<br>>
--
<br>>
Tereza Cavazos
<br>>
Departamento de Oceanografia Fisica
<br>>
CICESE
<br>>
Ensenada, Baja California, MEXICO
<br>>
<a href="http://usuario.cicese.mx/%7Etcavazos/" target="_blank">http://usuario.cicese.mx/~tcavazos/</a>
<br>>
<br>>
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</font></span></blockquote>
<br>>
<br clear="all">
<br>> --
<br>> Alireza
Azargoun
<br>
</div></div></font>
</div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Alireza Azargoun<br>