Heat Index plots in GRADS

[Kevin M Levey]

FRI 11MAY07: 0915PDT

Hi Bernd

Thank you so much for the help - I had another response instructing me  to
use the same.

Have a great weekend!


Regards

Kevin M Levey, MSc (University of Cape Town)
Director of Meteorological Operations
CustomWeather, Inc
San Francisco, CA, USA

http://www.1stweather.com
http://www.myforecast.com
http://www.customweather.com


> -----Original Message-----
> From: GRADSUSR at LIST.CINECA.IT [mailto:GRADSUSR at LIST.CINECA.IT] On
> Behalf Of bernd.becker at METOFFICE.GOV.UK
> Sent: Friday, May 11, 2007 2:00 AM
> To: GRADSUSR at LIST.CINECA.IT
> Subject: Re: Heat Index plots in GRADS
>
> Kevin,
>
> lookup in the grads documentation under "maskout"!
> That should do the trick.
> Bernd.
>
> On Thu, 2007-05-10 at 09:51 -0700, Kevin M Levey wrote:
> > THU 10MAY07: 0940PDT
> >
> >
> >
> > Hi
> >
> >
> >
> > I was wondering if anyone has done Heat Index (HI) plotting in GRADS?
> > I have the correct HI formula, but I get erroneous output since GRADS
> > is calculating the HI at every point for every temp. However, HI
> > should only be calculated for temps > 80F (26C). So, what happens is,
> > GRADS calculates the HI for values < 80F (< 26C) when these points
> > should NOT have HI values and the plot is a mess - showing both valid
> > and non-valid HI values. I am pretty adept using GRADS, however, I've
> > been working on this for days and can't seem to figure out how to get
> > GRADS to ignore values below the HI threshold. Has anyone come across
> > this problem before? I am using GFS data.
> >
> >
> >
> > Many thanks!
> >
> >
> >
> > Below is a typical GRADS script for producing HI.
> >
> >
> >
> > Regards
> >
> >
> >
> > Kevin M Levey, MSc (University of Cape Town)
> >
> > Director of Meteorological Operations
> >
> > CustomWeather, Inc
> >
> > San Francisco, CA, USA
> >
> >
> >
> > http://www.1stweather.com
> >
> > http://www.myforecast.com
> >
> > http://www.customweather.com
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > *002hr 0 DAY 1
> >
> > 'set mpdset hires'
> >
> > 'set mpt * off'
> >
> > 'set mpt 0 1 1 6'
> >
> > 'set mpt 1 1 1 1'
> >
> > 'set display color white'
> >
> > 'clear'
> >
> > 'open /prod/custom/intModel/GFS/temp/gfs_001.ctl'
> >
> > 'set xsize 800 600'
> >
> > 'set lat -36 -16'
> >
> > 'set lon 10 36'
> >
> > 'set map auto 1 1 6'
> >
> > 'set lev 1000'
> >
> > 'define temp = TMP2M - 273.16'
> >
> > 'define tempF = (temp *1.8) +32'
> >
> > 'define v = VGRDprs*3.6'
> >
> > 'define u = UGRDprs*3.6'
> >
> > 'define windkmh = mag(u,v)'
> >
> > 'define rh = RH2M'
> >
> > 'define HI = ((-42.379 + (2.04901523*tempF) + (10.14333127*rh) -
> > (0.22475541*tempF*rh) - (0.00683783*pow(tempF,2)) - (0.05481717*pow
> > (rh,2)) + (0.00122874*pow(tempF,2)*rh) + (0.00085282*tempF*pow(rh,2))
> > - (0.00000199*pow(tempF,2)*pow(rh,2)))-32)*5/9'
> >
> > *draw heat index map
> >
> > 'run /prod/custom/intModel/GFS/scripts/rgbset_HI1.gs'
> >
> > 'set gxout shaded'
> >
> > 'set cint 2.5'
> >
> > 'set cmin 40'
> >
> > 'set csmooth on'
> >
> > 'set grads off'
> >
> > 'd HI'
> >
> > 'set ccolor 0'
> >
> > 'set gxout contour'
> >
> > 'set cint 2.5'
> >
> > 'set cmin 30'
> >
> > 'set csmooth on'
> >
> > 'd HI'
> >
> > 'run /prod/custom/intModel/GFS/scripts/SA_cities.gs'
> >
> > 'run /prod/custom/intModel/GFS/scripts/cbarn'
> >
> >
> >
> > 'draw title HEAT INDEX (C)\INIT: 12UTC 13MAR07
> > VALID: 02H00 TUE 13 MAR 2007'
> >
> > 'printim /prod/custom/intModel/GFS/temp/GFS_HEAT_INDEX_PLOT1.png
> png
> > x800 y600'
> >
> > 'reinit'
> >
> >
> --
> Bernd Becker   The Monthly Outlook
> Met Office  FitzRoy Road  Exeter   Devon EX1 3PB  United Kingdom
> Tel.: +44 (0) 1392 884511 Fax: +44 (0)870 900 5050
> E-mail:bernd.becker at metoffice.gov.uk -  http://www.metoffice.gov.uk