[gradsusr] draw contour border

[Mubashar Ahmad]

Dear Jeff,

Thank you so much for such a nice explanation. Following your commands the
following commands works as you advised.

'set clevs 0'
 'd maskout(MassFluxMean,abs(lat-32.5)-12.5)'

Regards,
Mubashar



On Mon, Feb 27, 2017 at 11:16 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:

> Mubashar,
> Again, as I suggested before, using a masking field that involves
> latitude. You can setup an alegebraic inequality that involves the absolute
> value of latitude (lat, in Grads...it is defined automatically for you)
> that will suffice as the mask expression. Basically you want to find
> 'center' and 'width' such that
>
> | lat - center | < width
>
> is satisfied by your 20-45 N band. Then you can just take the logical
> negation of that statement and use it as the mask expression. I'll give you
> a hint by telling you that the equation satisfied by latitude values of 20
> to 45 N is
> | lat - 32.5 | < 12.5
>
> All that's left for you is to negate that and bring the 12.5 over to the
> other side, because in the maskout command you can only input the LHS of
> the equation. The RHS is assumed to be zero, hence the description
> "Wherever the *mask* values are less than zero, the values in *expr* are
> set to the missing data value." in the Grads User's Guide index entry for
> the maskout function.
>
> Jeff Duda
>
> On Mon, Feb 27, 2017 at 2:00 PM, Mubashar Ahmad <mubashardogar at gmail.com>
> wrote:
>
>> Dear Jeff and Davide,
>>
>> Thank you very much. Actually I would like to plot 0 value contours as
>> shown in the attached figures, but I don't need to display these contours
>> and 0 labels between latitude 20N til 45N. I just need to have these labels
>> and contours over the tropical region. The attached plot is done using
>> following maskout expression. MassFluxMean is the name of the variable.
>>
>> 'set clevs 0'
>> 'd maskout(MassFluxMean,0)'
>>
>> Best regards,
>> Mubashar
>>
>>
>> On Mon, Feb 27, 2017 at 8:38 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>>
>>> Unless you have a strict objective way to define the ITCZ, you may not
>>> be able to get the exact results you want. But one thing you can try is to
>>> mask your field by latitude:
>>>
>>> 'd maskout(field,abs(lat)-10)'
>>>
>>> The above command would plot a field only within 10 deg. of the equator.
>>> Adjust for your specific longitude band.
>>>
>>> Jeff Duda
>>>
>>> On Mon, Feb 27, 2017 at 7:04 AM, Mubashar Ahmad <mubashardogar at gmail.com
>>> > wrote:
>>>
>>>> Dear GrADS users,
>>>>
>>>> I would like to draw 0 contour border (over tropical  ITCZ region) in
>>>> the upper panel of attached figure. If I simply use command "set gxout
>>>> contour, or 'set clevs 0'  and then display my variable it will draw many
>>>> contours, but I don't want to display 0 values every where, instead  I want
>>>> it across ITCZ area (tropical region, red color) in the upper panel of
>>>> attached figure. How can I do it in GrADS?
>>>>
>>>> Thanks and best regards,
>>>>
>>>> Mubashar
>>>>
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>>>>
>>>>
>>>
>>>
>>> --
>>> Jeff Duda
>>> Post-doctoral research fellow
>>> University of Oklahoma School of Meteorology
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
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>>>
>>>
>>
>>
>> --
>> Muhammad Mubashar Ahmad Dogar
>> Scientific Officer (Climatology Section),
>> Global Change Impact Studies Centre (GCISC),
>> NCP complex, Quaid-e-Azam University Campus,
>> Shahdra road, Islamabad, Pakistan.
>> email: muhammad.dogar at kaust.edu.sa
>>            mubashardogar at gmail.com
>>            mubashardogar at yahoo.com
>>
>
>
>
> --
> Jeff Duda
> Post-doctoral research fellow
> University of Oklahoma School of Meteorology
>



-- 
Muhammad Mubashar Ahmad Dogar
Scientific Officer (Climatology Section),
Global Change Impact Studies Centre (GCISC),
NCP complex, Quaid-e-Azam University Campus,
Shahdra road, Islamabad, Pakistan.
email: muhammad.dogar at kaust.edu.sa
           mubashardogar at gmail.com
           mubashardogar at yahoo.com
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