[gradsusr] how to find pressure highs and lows ?

[avi kojokro]

Wow, what a great script
I do not understand one thing.
I changed the script a bit and put H500 with SLP, after I do the map I do
not understand why he do not draw the L instead the  X  I marked on the map? ,
In this place there is a ground low.
I am attaching the map and the script.


2013/10/2 Matias Mendez <matias.mendezp at gmail.com>

> Kishore
>
> I use OpenGrADS  that includes User Defined Extensions. Look at here:
>
> http://opengrads.org/doc/udxt/libmf/
>
> Good luck
> Matias
>
>
>
>
>
> 2013/10/2 Kishore Ragi <kishoreragi at gmail.com>
>
>> Matias,
>>
>> I am on the site only but, mfhilo is not working. Simply, it is saying
>> the following.
>>
>> mfhilo prmslmsl/100 CL l 1000, 300
>> Unknown command: mfhilo
>>
>> do you have any idea in which version of grads included?
>>
>> Thank you,
>>
>> Regards,
>>
>> Kishore
>>
>>
>> On Wed, Oct 2, 2013 at 11:43 PM, Matias Mendez <matias.mendezp at gmail.com>wrote:
>>
>>> Hello Kishore,
>>>
>>> Please look at the following link:
>>>
>>>
>>> http://gradsaddict.blogspot.mx/2013/05/tutorial-draw-sea-level-pressure-map.html
>>>
>>> You can get good GrADS tutorials and scripts there.
>>>
>>> Good luck.
>>>
>>>
>>> Matias
>>>
>>>
>>>
>>>
>>> 2013/10/2 Kishore Ragi <kishoreragi at gmail.com>
>>>
>>>> Dear grads users,
>>>>
>>>> Could anyone please tell me how find out pressure lows and highs with
>>>> symbols L's and H's respectively with netcdf data set?
>>>>
>>>> thank you,
>>>>
>>>> Ragards,
>>>>
>>>> Kishore
>>>>
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>>>>
>>>
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>>>
>>
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>
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radius=1000
cint=300

'sdfopen http://nomads.ncep.noaa.gov:9090/dods/gfs_hd/gfs_hd20131004/gfs_hd_00z'


'set lat 20 55'
'set lon 8 55'

prompt 'Enter day dd? '
pull day
prompt 'Enter month (Jan,Feb)? '
pull mon
prompt 'Enter hour zz? '
pull hour
'set time 'hour'z'day''mon'2013'
'set display color white'
'clear'
'set map 1'
'set mpdset hires'
'set lev 500'
'set gxout shaded'
'500colorhgt1'
'd hgtprs/10'
'cb5'
'set gxout contour'
'set cint 4'
'set ccolor 1'
'd hgtprs/10'
'set cmin 940'
'set cmax 1040'
'set cint 1'
'set ccolor 0'
'set clab masked'    
'set cthick 6'
'd prmslmsl/100'

*   ******************************DRAW L's******************************

'mfhilo prmslmsl/100 CL l 'radius', 'cint

Low_info=result
i=2         ;*Since the data starts on the 2nd line
minmax=sublin(Low_info,i)

while(subwrd(minmax,1) = 'L') 

  min_lat = subwrd(minmax, 2)
  min_lon = subwrd(minmax, 3)
  min_val = subwrd(minmax, 5)

  'q w2xy 'min_lon' 'min_lat      ;*Translate lat/lon to page coordinates
   x_min = subwrd(result,3)
   y_min = subwrd(result,6)


  'q gxinfo'                      ;*Get area boundaries
  xline=sublin(result,3)
  yline=sublin(result,4)
  xs=subwrd(xline,4)' 'subwrd(xline,6)
  ys=subwrd(yline,4)' 'subwrd(yline,6)

  if(y_min > subwrd(ys,1)+0.1 & y_min < subwrd(ys,2)-0.1 & x_min > subwrd(xs,1)+0.1 & x_min < subwrd(xs,2)-0.5)
    'set strsiz .28'
    'set string 2 c 9'
    'draw string 'x_min' 'y_min' L'
        
    'set strsiz 0.1'
    'set string 2 bl 2'
    'draw string 'x_min+0.1' 'y_min-0.15' 'min_val
  endif

  i=i+1
  minmax = sublin(Low_info,i)
endwhile

*   ******************************DRAW H's******************************

     'mfhilo prmslmsl/100 CL h 'radius', 'cint

      High_info=result
      i=2         ;*Since the data starts on the 2nd line
      minmax=sublin(High_info,i)

while(subwrd(minmax,1) = 'H') 

  min_lat = subwrd(minmax, 2)
  min_lon = subwrd(minmax, 3)
  min_val = subwrd(minmax, 5)

  'q w2xy 'min_lon' 'min_lat      ;*Translate lat/lon to page coordinates
   x_min = subwrd(result,3)
   y_min = subwrd(result,6)


  'q gxinfo'                      ;*Get area boundaries
  xline=sublin(result,3)
  yline=sublin(result,4)
  xs=subwrd(xline,4)' 'subwrd(xline,6)
  ys=subwrd(yline,4)' 'subwrd(yline,6)

  if(y_min > subwrd(ys,1)+0.1 & y_min < subwrd(ys,2)-0.1 & x_min > subwrd(xs,1)+0.1 & x_min < subwrd(xs,2)-0.5)
    'set strsiz .28'
    'set string 4 c 9'
    'draw string 'x_min' 'y_min' H'
        
    'set strsiz 0.1'
    'set string 4 bl 2'
    'draw string 'x_min+0.1' 'y_min-0.15' 'min_val
  endif

  i=i+1
  minmax = sublin(High_info,i)
endwhile


***


'q time'
btime = subwrd(result,3)
bhour = substr(btime,1,3)
bday = substr(btime,4,9)
'draw title  'bday':'bhour'  -'day'-'mon'-2013 'hour'Z SLP'
'printim hi-low1.png x1400 y1000'
'end'
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