Re: anyone can help me to plot the skew T

From: Adam Phillips <asphilli_at_nyahnyahspammersnyahnyah>
Date: Thu Mar 04 2010 - 09:55:26 MST

Hi Ali,
Our apologies that it took so long for someone to get back to you on
this. The quick answer is that the skew-t coding does not draw the CAPE
parcel profile if the calculated CAPE value is less than 0. In your
case, it's -17515. You can manually override this behavior by modifying
the skew-t code, located here:
$NCARG_ROOT/lib/ncarg/nclscripts/csm/skewt_func.ncl

On line 827, alter this:
       if (localOpts@Cape .and. cape.gt.0.) then
to this:
       if (localOpts@Cape) then

Adam

On 03/02/2010 07:27 PM, z3303149@unsw.edu.au wrote:
> Hi group
>
> i'm trying to plot skew T digram , i got the plot but without the
> pseudoadiabates curve (red line) like in example 2 in skewt examples , i have
> attachment the figure i got it if anyone can help me.
>
> thanks
>
> Ali
>
>
>
>
>
>
>
>
>
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/skewt_func.ncl"
>
>
>
> begin
>
>
>
>
>
>
>
> colmin = 40
> colmax = 47
> rowmin = 33
> rowmax = 40
>
>
>
> class = 4
>
>
>
>
> diri = "/srv/science/maths1/z3236814/data02/swap/co2/fc/"
>
>
>
> f = addfile(diri+"evb_minclass_200noev_2000.nc","r") ; open data netcdf file
>
> topo = f->terrain
> w = f->w(class-1,:,:,:,:)
> u = f->u(class-1,:,:,:,:)
> v = f->v(class-1,:,:,:,:)
> t = f->t(class-1,:,:,:,:)
> q = f->q(class-1,:,:,:,:)
> pp = f->pp(class-1,:,:,:,:)
> sigma = f->sigma_level
> ps = f->pstarcrs
> time = f->time
> lat = f->latitcrs
> lon = f->longicrs
> ptop = f->ptop
>
>
>
>
> dsize = dimsizes(q)
> pres = new(dsize,float)
>
>
> ;to calculate the pressure for each grid point
> pres = pp + ptop +conform(pp,ps,(/2,3/))*conform(pp,sigma,1)
>
>
> rel = relhum(t,q,pres)
>
>
>
> ;to calculates the dewpoint temperature
> dewpoint= dewtemp_trh(t,rel)
>
>
> dewpoint = dewpoint -273 ;returned depoint temperature in (C)
>
>
> ; to define the dewpoint
> dewpoint!0 = "time"
> dewpoint!1 = "sigma_level"
> dewpoint!2 = "i_cross"
> dewpoint!3 = "j_cross"
>
> pres = pres*0.01 ; to converte it to (hPa)
>
> ;calculate virtual temperature
> vir_temp = new(dsize,float)
> vir_temp = t*(1.+q*0.61)
>
>
>
> ; to define the pres
> pres!0 = "time"
> pres!1 = "sigma_level"
> pres!2 = "i_cross"
> pres!3 = "j_cross"
>
> ; to define the virtual temperature
> vir_temp!0 = "time"
> vir_temp!1 = "sigma_level"
> vir_temp!2 = "i_cross"
> vir_temp!3 = "j_cross"
>
>
>
>
>
> t = t-273 ; to converte it to (C)
>
>
>
>
> gh = hydro(pres(time|:,i_cross|:,j_cross|:,sigma_level|::-1), \
> vir_temp(time|:,i_cross|:,j_cross|:,sigma_level|::-1), \
> conform(vir_temp(:,0,:,:),topo,(/1,2/)))
>
>
>
>
> ; to define the geopotential height
> gh!0 = "time"
> gh!1 = "i_cross"
> gh!2 = "j_cross"
> gh!3 = "sigma_level"
>
>
>
>
>
>
>
> ;to calculates the meteorological wind direction
> r2d = 45.0/atan(1.0) ;to conversion from radians to degrees because the return
> value in radians
> wdir = atan2(u,v)* r2d + 180
>
>
>
> wdir!0 = "time"
> wdir!1 = "sigma_level"
> wdir!2 = "i_cross"
> wdir!3 = "j_cross"
>
>
> wks = gsn_open_wks ("eps", "skewclass62095")
>
>
> pres1=
> dim_avg(dim_avg(pres(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
> z =
> dim_avg(dim_avg(gh(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
> wind =
> dim_avg(dim_avg(v(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
> windd=
> dim_avg(dim_avg(wdir(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
> temp =
> dim_avg(dim_avg(t(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
> dew1 =
> dim_avg(dim_avg(dewpoint(time|:,sigma_level|:,i_cross|rowmin:rowmax,j_cross|colmin:colmax)))
>
>
>
>
>
>
> skewtOpts = True
> skewtOpts@DrawFahrenheit = False
> skewtOpts@DrawWind = True
> skewtOpts@DrawHeightScale = True
>
>
> dataOpts = True ; options describing data and ploting
> dataOpts@linePatternDewPt = 1
> dataOpts@colDewPt = "red"
>
> ;add legend
> legend = create "Legend" legendClass wks
> "vpXF" : 0.15
> "vpYF" : 0.88
> "vpWidthF" : 0.24 ; width
> "vpHeightF" : 0.09 ; height
> "lgPerimOn" : True ; perimeter
> "lgItemCount" : 2 ; how many
> "lgLabelStrings" : (/"Temperature","Dew point Temperature"/)
> "lgLineThicknessF" : 3.0
> "lgBoxMinorExtentF" : 0.2
> end create
>
>
>
>
> skewt_bkgd = skewT_BackGround (wks, skewtOpts)
>
> skewt_data=skewT_PlotData(wks,skewt_bkgd,pres1(15,:),temp(15,:),dew1(15,:),z(15,:),wind(15,:),windd(15,:),dataOpts)
>
>
>
>
>
> draw (skewt_data)
> draw (skewt_bkgd)
>
> draw(legend)
> frame(wks)
>
>
>
>
> end
>
>
>
>
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-- 
__________________________________________________
Adam Phillips 
asphilli@ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
Climate and Global Dynamics Division         fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000    http://www.cgd.ucar.edu/cas/asphilli
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Received on Thu Mar 4 09:55:31 2010

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