trenberth.sh

#! /bin/bash -f
#---------------------
# GEMPAK Trenberth map
# 
# Programs used		GDCNTR
#			GDWIND
# Author		Michael James, Unidata
# Last Updated		June 2012
# 
# ABOUT
#--------------
# The traditional omega equation identifies fundamental processes
# that determine vertical motion.  However, it has the disadvantage
# of being difficult to evaluate because of two terms (temperature 
# advection term and differential vorticity advection term) cancel
# in some situations.
#
# The Trenberth formulation presents an equation which contains both 
# temperature and geostrophic vorticity at just one level, and in one
# term.  Temperature usually increases southward, so where geostrophic
# vorticity decreases toward the east, the result is positive vorticity
# advection, the result being ascent (negative omega).
#
# See http://weather.ou.edu/~mjames/gempak/TrenberthFormulation.html
# for a more detailed explanation.
#
#------------

. /home/gempak/NAWIPS/Gemenviron.profile

# set working directories
GFSdir=$MODEL/gfs

# set date/time
YYYYMMDD=`date -u +%Y%m%d`
HHNN=`date -u +%H%M`

# set forecast time to use, default 12-hr
FTIME=f012

# get latest GFS file 
lastFile=`ls $GFSdir | grep gfs211 | tail -1`

# full path and file name
GDFILE=$GFSdir/$lastFile

# GEMPAK variables: projection, data bounds, and title
DATAAREA='20;-130;52;-50'
PROJ='str/90;-100;0'
TITLE='700 mb Vorticity / 1000-500 mb Thermal Wind'

# set device
# default is gif image, user will comment/uncomment here to select X Window 
DEV='gif|trenberth.gif|1024;768'
#DEV='xw|xw|900;600'

# The Trenberth map uses two runs through GDCNTR: 
# 1) 700 mb vorticity color-filled contours
# 2) 500-1000 mb heights

gdcntr <<EOF1
 GDFILE   = $GDFILE
 GDATTIM  = $FTIME
 GLEVEL   = 700
 GVCORD   = pres
 PANEL    = 0
 SKIP     = 
 SCALE    = 5
 CTYPE    = f
 GFUNC    = avor(wnd)
 CONTUR   = 2
 CINT     = 2
 LINE     = 1/1
 FINT     = 10;12;14;16;18;20;22;24
 FLINE    = 101;21;22;23;5;19;17;16;15;5
 HILO     =
 HLSYM    =
 CLRBAR   = 31/V/LL/
 WIND     = 0
 REFVEC   =
 TITLE    = 31/-2/GFS ~
 TEXT     = 1/2//hw
 CLEAR    = n
 GAREA    = us
 IJSKIP   = 0
 PROJ     = $PROJ
 MAP      = 6
 MSCALE   = 0
 BND      = lakes/24
 LATLON   = 0
 DEVICE   = $DEV
 STNPLT   =
 SATFIL   = 
 RADFIL   =
 IMCBAR   =
 LUTFIL   = 
 STREAM   =
 POSN     = 0
 MARKER   = 0
 GRDLBL   = 0
 FILTER   = YES
r

 GLEVEL  = 500:1000
 GFUNC   = SUB(HGHT@500,HGHT@1000)
 CINT    = 60
 LINE    = 5/1/2
 SCALE   = 0
 CLRBAR  =
 TITLE   = 31/-1/ $TITLE 
 CONTUR  = 3
 SKIP    = 0/1
 FINT    = 70;90;110;130;150
 FLINE   = 0;25;24;29;7;15
 CTYPE   = c
r

e
EOF1

# overlay thermal wind
gdwind << EOF3
   GVECT   = thrm(hght)
   CTYPE   = 
   CINT    = 
   LINE    = 6/1/2
   CLEAR   = n
   WIND    = bk31/.5//2
   TEXT    = 
   CONTUR  = 0
   r

   e
EOF3

# cleanup
#
# gpend should be commented out if you're testing with X Windows, 
# otherwise it will close immediately after it opens
#
# also remove nts files from current working directory
gpend
rm last.nts
rm gemglb.nts