[gradsusr] Max Value Coordinates

[sushant puranik]

What if i want to find the level of maximum wind and also the track how
maximum wind flows?

sushant

On Mon, Oct 25, 2010 at 10:13 PM, Charles Seman <Charles.Seman at noaa.gov>wrote:

> Andrew and Jeff and GrADS Users,
>
> Kun-Hsuan Chou provided the reference code for this technique (which can be
> found in the attached file hurricane_tracking.txt, taken from an email
> exchange posted to the GrADS Listserv by Kun-Hsuan Chou and Arturo Caracas
> Uribe in Oct, 2004).
>
> Chuck
>
> Jeffrey Duda wrote:
>
>> Andrew,
>> I had posted a request on this forum about this exact question in August.
>>  I believe it was Charles Seaman who provided the answer.  The meat of the
>> code is
>>
>> 'd maxloc(max('ans',x='x1',x='x2'),y='y1',y='y2')'
>>  yline = sublin(result,2)
>>  ymax = subwrd(yline,4)
>> 'd maxloc(max('ans',y='y1',y='y2'),x='x1',x='x2')'
>>  xline = sublin(result,2)
>>  xmax = subwrd(xline,4)
>>
>>
>> where "ans" refers to the field for which you want to find the max/min,
>> and x1, x2 refer to x-grid values or longitude points and y1, y2 refer to
>> y-grid values or latitude points.  xmax, ymax are the coordinates of the
>> maximum value.  To find the minimum, just replace maxloc and max with minloc
>> and min.
>>
>> Jeff Duda
>>
>> On Fri, Oct 22, 2010 at 7:43 PM, Andrew Revering <andy at f5data.com<mailto:
>> andy at f5data.com>> wrote:
>>
>>    I'd like to have the coordinates of our 'max value'… I know about
>>    maxloc(), and tried various examples I found in forums,
>>    documentation and email conversations, but I can't seem to get it
>>    to perform as I expect.
>>
>>
>>    When it supposedly works, I just see some white lines on the
>>    bottom and right of my image (not where the max value is)… is
>>    there a way to actually get lat/lon coordinates of the max value?
>>
>>
>>    I should note that in my situation there will be the teeniest dot
>>    of plotted value, the rest of the grid is blank. I don't know if
>>    that matters in these functions.
>>
>>
>>    Andrew Revering
>>
>>    Convective Development, Inc.
>>
>>    http://www.convectivedevelopment.com/
>>
>>
>>
>>
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>>
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>>
>>
>>
>>
>> --
>> Jeff Duda
>> Iowa State University
>> Meteorology Graduate Student
>> 3134 Agronomy Hall
>> www.meteor.iastate.edu/~jdduda <http://www.meteor.iastate.edu/%7Ejdduda><
>> http://www.meteor.iastate.edu/%7Ejdduda>
>> ------------------------------------------------------------------------
>>
>>
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>>
>
> --
>
> Please note that Charles.Seman at noaa.gov should be considered my NOAA
> email address, not cjs at gfdl.noaa.gov.
>
> ********************************************************************
> Charles Seman                                Charles.Seman at noaa.gov
> U.S. Department of Commerce / NOAA / OAR
> Geophysical Fluid Dynamics Laboratory         voice: (609) 452-6547
> 201 Forrestal Road                              fax: (609) 987-5063
> Princeton, NJ  08540-6649            http://www.gfdl.noaa.gov/~cjs/<http://www.gfdl.noaa.gov/%7Ecjs/>
> ********************************************************************
>
> "The contents of this message are mine personally and do not reflect any
> official or unofficial position of the United States Federal Government,
> the United States Department of Commerce, or NOAA."
>
>
> *
> *
> * Subject: Re: Tracking Hurricanes
> * From: Kun-Hsuan Chou <cwujou at TYPHOON.AS.NTU.EDU.TW>
> * Date: Fri, 8 Oct 2004 08:03:20 +0800
> * To: GRADSUSR at LIST.CINECA.IT
> *
> * Hi,
> *
> * I write a sample to track the maxminum wind speed, it should be the
> script that you want.
> *
> 'd maxloc(max(mag(u,v),lon=120,lon=130),lat=15,lat=25)'
>  line=sublin(result,2)
>  ygrd=subwrd(line,4)
> 'd maxloc(max(mag(u,v),lat=15,lat=25),lon=120,lon=130)'
>  line=sublin(result,2)
>  xgrd=subwrd(line,4)
> 'set x 'xgrd
> lonval = subwrd(result,4)
> 'set y 'ygrd
> latval = subwrd(result,4)
> 'q w2xy 'lonval' 'latval
> xpos = subwrd(result,3)
> ypos = subwrd(result,6)
> 'draw mark 1 'xpos' 'ypos' .2'
>
>
> *============================================================================
> *Kun-Hsuan Chou
> *Postdoctoral Researcher
> *Department of Atmospheric Sciences
> *National Taiwan University
> *No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan.
> *Phone:   886-2-23625896 ext. 243
> *Mobile:  0920079247
> *E-mail:   cwujou at typhoon.as.ntu.edu.tw
> *----- Original Message -----
> *From: Arturo Caracas Uribe
> *To: GRADSUSR at LIST.CINECA.IT
> *Sent: Thursday, October 07, 2004 11:48 PM
> *Subject: Tracking Hurricanes
> *
> *Does anyone know how to get the maximum values of vorticity of a domain?
> (the value, lat and lon).I need the positions in order to track a hurricane.
> *Thanks in advance
> *
> *Arturo Caracas
> *Atmospheric Sciences, México.
>
>
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