[gradsusr] If Statements for Gridded Model Data Open GrADS

[Becker, Bernd]

Matt,

read up on maskout and const:

'define mx = const( const( maskout(tmax     ,tmax     -30),1),0,-u)'
'define mn =const(  const( maskout(tmin     ,tmin     -15),1),0,-u)'

in your case something like:

'define mx = const( const( maskout(NAMcape     ,NAMcape    -1500),1),0,-u)'
might work .
Cheers,
Bernd.

From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Baker, Matt (Quebec - Atlantic)
Sent: 22 June 2016 14:25
To: gradsusr at gradsusr.org
Subject: [gradsusr] If Statements for Gridded Model Data Open GrADS

Hi all,

I have a question regarding Open GrADS.

I’m trying to use if statements for scalar model data (eg. GFS and NAM) over a grid and I’m wondering if it’s possible to do this. As an example, I’m using if statements for these parameters: surface based CAPE, LI, and 500 mb relative humidity to create an index to plot on a map. So far GrADS isn’t showing that this is working, however, I can plot the model data individually so I don’t think it’s a case of missing data.

Here’s some of the code for the NAM model. Note that I define the variable NAMHail to equal 0 at the start of the function.

   if (modelNumberNAM>0)
        set_maps(_map,_hasNegativeNAM)
        'set grads off'
        'set grid off'
        'set gxout contour'
        'set ccolor 0'
        'set clopts -1 1 0.15'
        'set cint 1'
        'set cthick 6'
        'set clab on'
        'set csmooth on'

        'NAMcape = CAPEsfc.'modelNumberNAM
        if (NAMcape > 1500 & NAMcape < 2200)
            'NAMHail = NAMHail + 1'
        endif
        if (NAMcape > 2199 & NAMcape < 3100)
            'NAMHail = NAMHail + 2'
        endif
        if (NAMcape > 3099)
            'NAMHail = NAMHail + 3'
        endif

        'set lev 500'
        'NAMrh500=RHprs.'modelNumberNAM
        if (NAMrh500 < 35)
            'NAMHail = NAMHail + 3'
        endif
        if (NAMrh500 > 35 & NAMrh500 < 44)
            'NAMHail = NAMHail + 1'
        endif

    endif

    'set gxout contour'
    'set ccolor 0'
    'set clopts -1 1 0.15'
    'set cint 200'
    'set cthick 6'
    'set clab on'
    'set csmooth on'

    'd NAMcape'

Thanks!

Matt Baker
Meteorologist, Met-Ocean Services, Amec Foster Wheeler Environment & Infrastructure
133 Crosbie Road, PO Box 13216, St. John’s, NL A1B 4A5, Canada
matt.baker at amecfw.com<mailto:matt.baker at amecfw.com>­­      amecfw.com
ISO 9001:2008 Quality Management System (St. John's)

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