VINT

[Remi Meynadier]

Well thanks for you answer

but :
> If ps>1000, e.g., 1030mb, I guess (from the explanation above) that only
> levels
> starting at 1000mb and above will be used... and the 30mb between ps and
> first
> level will just be lost.

let's consider the case where ps=1030 >1000
I ve tried vint(ps,q,300) and vint(const(q,1000),q,300) and it's not the
same the result !!

And i have not tried for the reverse case (ps=915)<1000 but let's say the
variable are defined on levels 1000 925 850, i am not sure that :
vint((ps=915),q,300)=vint(const(q,850),q,300).

So for me there is still something not clear in grads documentation.
I believe that these questions are especially relevant to regions with
high altitude relief.
Thanks in advance

Remi


> Dear Meynadier,
>
> From the grads documentation:
>
> (...)The summation is done for each layer present that is between the
> bounds. The layers are determined by the Z levels of the default file.
> Each layer is considered to be from the midpoints between the levels
> actually present, and is assumed to have the same value throughout the
> layer, namely the value of the gridpoint at the middle of the layer.
>
> If ps<1000, e.g. 915mb, the integration will exclude all levels below
> 915mb.
>
> If ps>1000, e.g., 1030mb, I guess (from the explanation above) that only
> levels
> starting at 1000mb and above will be used... and the 30mb between ps and
> first
> level will just be lost.
>
> Sincerely,
> Henrique
>
> On Thu, Feb 28, 2008 at 8:33 PM, Remi Meynadier
> <remi.meynadier at aero.jussieu.fr> wrote:
>> Hi folks
>>  I am using the vint fonction to integrate specific humidity to obtain
>>  precipitable water.
>>
>>  This is what I ve done : vint(ps,q,100) with ps surface pressure.
>>
>>  What does the vint fonction do when the first pressure level (ie
>> 1000hPa)
>>  is above surface pressure ? An extrapolation from the first pressure
>> level
>>  ?
>>
>>  and in the same time what if ps is lower than 1000hPa ?
>>
>>  Thanks in advance
>>  Regards
>>
>>
>>  --
>>  Rémi Meynadier
>>  Institut Pierre Simon Laplace
>>  Service d'Aéronomie du CNRS, UMR 7620
>>  Université Pierre et Marie Curie
>>  Tour 45-46, 3e étage, Case 102
>>  4 place Jussieu, 75252 PARIS Cedex 05
>>  Tél: 01 44 27 84 45 Fax: 01 44 27 37 76
>>
>


--
Rémi Meynadier
Institut Pierre Simon Laplace
Service d'Aéronomie du CNRS, UMR 7620
Université Pierre et Marie Curie
Tour 45-46, 3e étage, Case 102
4 place Jussieu, 75252 PARIS Cedex 05
Tél: 01 44 27 84 45 Fax: 01 44 27 37 76