[gradsusr] Finding zonal wind core value, and its position

[Muhammad Yunus Ahmad Mazuki]

I see, using derivatives and its product to determine the points, then I
can use it to fine tune my search. Thank you very much

Muhammad Yunus

On Thu, Dec 13, 2012 at 11:37 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:

> Perhaps look for both maxima and just automatically reject the one that is
> more poleward.  You can use the cdiff function to compute derivatives and
> run the first derivative test to find maxima.
>
> Jeff
>
>
> On Wed, Dec 12, 2012 at 8:38 PM, Muhammad Yunus Ahmad Mazuki <
> ukm.yunus at gmail.com> wrote:
>
>> Well, I'm also looking into other ways in doing this, other than
>> scripting in GrADS. There are two jet stream, subtropical and polar front,
>> and I want to track the subtropical jet even when it is weak in strength.
>> I'm also looking at how to search it degree by degree (or rather y and z
>> point in GrADS), with some rules. This is because when there is a need to
>> introduce some events in a model that literally wrecks the usual pattern of
>> the subtropical jet stream, I need to be sure that my calculation is
>> tracking purely subtropical jet stream.
>>
>> Muhammad Yunus
>>
>> On Wed, Dec 12, 2012 at 1:44 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>>
>>> This is hard to get around given the rules you've set forth.  If you
>>> can't restrict your search box yet you don't want the maxima that occur at
>>> certain spots, how can you tell a script to make that distinction?  What is
>>> it about the one jet core that makes it the one you want?  When you can
>>> answer that, then you know how to adjust your search to always get the jet
>>> core you want.
>>>
>>> Jeff Duda
>>>
>>> On Tue, Dec 11, 2012 at 1:18 AM, Muhammad Yunus Ahmad Mazuki <
>>> ukm.yunus at gmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> The picture attached is a slice of longitude 180E, from 40 S to 20S. As
>>>> you can see, the core that I wanted is at the 23S with wind speed of 18. I
>>>> have tried using maximum value function in grads, as well as maximum
>>>> location, but it would give me 39S corresponding to a core below 40S, which
>>>> I do not want. I would like to request suggestion on solving this problem.
>>>> Changing the latitude range to less than 40S however is not acceptable, as
>>>> at certain condition the core can be at 38 S.
>>>>
>>>> Sincerely,
>>>> Muhammad Yunus
>>>>
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>>>>
>>>
>>>
>>> --
>>> Jeff Duda
>>> Graduate research assistant
>>> University of Oklahoma School of Meteorology
>>> Center for Analysis and Prediction of Storms
>>>
>>>
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>>>
>>
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>>
>
>
> --
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
>
>
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