Re: Montgomery streamfunction

Claudia,

Looking at your plot, and noting that the level you are plotting is
294K, it
appears that that level would be below ground in the western part of
your
domain where higher elevations exist. For example at 12Z
today, Denver had a surface temp of 283K and a surface
pressure of 831 mb, so the THTA at the surface was 299K. With a stable
atmosphere, THTA was >300 at all levels.

You had set SEARCH to include /EX so you are allowing extrapolation
to the higher elevations but the edge effects are apparent in your
pressure contours
in the right panel. Note that the montgomery stream function is
integrated
from Cpdt + gdz, so it will be slightly more sensitive to the bottom
level existing, 
as it integrates upward. All those contours out west are likely just
extrapolated PRES values. You may want to grid the PRES at SFC and
mask(PRES,slt(pres,PSFC)), or show where your 294K exists above ground.

Steve Chiswell
Unidata User Support


On Fri, 2007-10-05 at 16:29 -0400, Claudia Walters wrote:
> Steve, 
> 
> 
> I am plotting the Montgomery stream function for a number of low-level
> jet case studies with the shell script below  I have a number of cases
> where the other variables are plotting fine on the isentropic surface,
> but the stream function will only plot for part of the area (see
> figures), or not at all.  Do you have any advice? 
> 
> 
> Thanks,
> Claudia
> 
> 
> 
> 
> Claudia K. Walters, Ph.D.
> Assistant Research Scientist
> Lecturer II of Geography
> Department of Social Sciences
> University of Michigan - Dearborn
> 4901 Evergreen Road
> Dearborn, MI 48128
> email: address@hidden
> phone: +1.313.593.5636
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ############################################################################
> 
> 
> set yrmo=$1
> set dy=$2
> set hr=$3
> set levl=$4
> set lat1=$5
> set lon1=$6
> set lat2=$7
> set lon2=$8
> set lat3=$9
> set lon3=$10
> set lat4=$11
> set lon4=$12
> 
> 
> echo "in nenviron_ksfc.csh"
> 
> 
> set soundingpath="/data/jet/noaacdrom/"
> set gridpath="/data/jet2/jetevents/isengrids/"
> set textpath="/data/jet2/jetevents/isentext/"
> set figurepath="/data/jet2/jetevents/Northerly_environment/"
> set output=ps
> 
> 
> set iparm="uwnd;vwnd;sped;pres;hght;tmpk;thta;thte;psym"
> 
> 
> set ll_isotach_line="8/1/3/2/1/"
> set isobar_line="8/2/7/1/1"
> set stream_line="1/1/2"
> set stream_line2="9/1/1"
> set Mont_line="1/1/5/2/0"
> set wind="am1/0.8/1//0.7"
> set title_text="1.0/33/HW"
> set map="10/1/2/"
> set box_line="1/1/3/1"
> set panel="ul"
> 
> 
> ############################################################################
> #
> #  Initialize Grid File
> #
> ############################################################################
> 
> 
> oagrid << endoagrid
> 
> 
> GDFILE=$gridpath$yrmo$dy$hr$levl.grd
> DELTAN=4.
> DELTAX=1.
> DELTAY=1.
> GRDAREA=20;-120;65;-70
> EXTEND=2;2;2;2
> DTAAREA=15;-125;70;-65
> SOURCE=SN
> SNFILE=$soundingpath${yrmo}.gem
> SFFILE=GEMDATA:HRCBOB.SFC
> SNPARM=$iparm
> SFPARM=
> DATTIM=$yrmo$dy/${hr}00
> LEVELS=$levl
> MAXGRD=500
> 
> 
> run
> 
> 
> endoagrid
> 
> 
> gpend
> 
> 
> echo "before performing objective analysis"
> 
> 
> ############################################################################
> #
> #  Perform objective analysis on sounding data on isentropic surfaces
> #
> ############################################################################
> 
> 
> oabsnd << endoabsnd
> 
> 
> SNFILE=$soundingpath${yrmo}.gem
> GDFILE=$gridpath$yrmo$dy$hr$levl.grd
> SNPARM=$iparm
> STNDEX= 
> LEVELS=$levl
> VCOORD=thta
> DATTIM=$yrmo$dy/${hr}00
> DTAAREA=15;-125;70;-65
> GUESS=
> GAMMA=.3
> SEARCH=20/EX
> NPASS=2
> QCNTL=
> 
> 
> run
> 
> 
> exit
> 
> 
> endoabsnd
> 
> 
> gpend
> 
> 
> 
> 
> ############################################################################
> #
> #  Plot isobars and Montgomery streamfunction on isentropic surfaces
> #
> ############################################################################
> 
> 
> gdplot << endgdplot
> 
> 
> GDFILE=$gridpath$yrmo$dy$hr$levl.grd 
> GDATTIM=$yrmo$dy/${hr}00
> GLEVEL=$levl
> GVCORD=thta
> PANEL=$panel
> SKIP=
> SCALE=
> GFUNC=pres
> CTYPE=C
> CONTUR=0/0 
> CINT=50 
> LINE=$isobar_line
> FINT= 
> FLINE=
> HILO=
> HLSYM=
> CLRBAR=
> GVECT=
> WIND=
> STREAM=
> REFVEC=
> TITLE=1/-2/^ @ Isobars (hPa) and Streamfunc 10^2 (J/kg)
> TEXT=$title_text
> CLEAR=yes 
> GAREA=20;-120;65;-70
> PROJ=ced
> MAP=$map
> LATLON=0
> DEVICE=$output
> STNPLT=
> 
> 
> run
> 
> 
> GFUNC=psym
> CINT=
> LINE=$Mont_line
> CLEAR=no
> MAP=0
> 
> run
> 
> 
> exit
> 
> 
> endgdplot
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
-- 
Steve Chiswell <address@hidden>
Unidata