Re: CCSM4 geopotential heights

Hi Mike

I do not see any issues.

Perhaps another approach at evaluation.

http://www.ncl.ucar.edu/Document/Functions/Built-in/cz2ccm.shtml

Use 'pres_hybrid_ccm' to get the pressure at the mid levels.
then use 'int2p' to interpolate to 500hPa?

Good luck

On 3/7/13 11:54 PM, Michael Notaro wrote:
> Does the script below for computing 500hPa geopotential heights from CCSM4 data
> look ok? The resulting values are slightly higher than I expected, by maybe 100 m,
> but perhaps I am wrong in my concern.
>
> Thanks, Michael
>
>
> nlat=192
> nlon=288
>
> mns=(/"JAN","FEB","MAR","APR","MAY","JUN","JUL","AUG","SEP","OCT","NOV","DEC"/)
>
> a=addfile("/data/Share/regcm_inputdata/CCSM4/historical/ccsm4.shumJAN.1971.nc","r")
> lat=a->lat
> lon=a->lon
> lev=a->lev(::-1)
> coefa=a->a(::-1)
> coefb=a->b(::-1)
> p0=a->p0
>
> b=addfile("/data/Share/regcm_inputdata/CCSM4/historical/orog_fx_CCSM4_historical_r0i0p0.nc","r")
> topo=b->orog ; height above sea level (m)
>
> data=new((/32,12,nlat,nlon/),float) ; 1973-2004
>
> do iy=0,31
> do im=0,11
>
> a=addfile("/data/Share/regcm_inputdata/CCSM4/historical/ccsm4.shum"+mns(im)+"."+(iy+1973)+".nc","r")
> q=a->hus(:,::-1,:,:) ; kg/kg spec hum
> w=q/(1.-q) ; convert spec hum to mixing ratio
> q=(/w/)
>
> time=a->time
> b=addfile("/data/Share/regcm_inputdata/CCSM4/historical/ccsm4.pres"+mns(im)+"."+(iy+1973)+".nc","r")
> ps=b->ps
> ps=ps/100.
> copy_VarCoords(b->ps,ps)
> c=addfile("/data/Share/regcm_inputdata/CCSM4/historical/ccsm4.air"+mns(im)+"."+(iy+1973)+".nc","r")
> t=c->ta(:,::-1,:,:)
>
> copy_VarCoords(t,q)
>
> zsfc=new((/dimsizes(time),nlat,nlon/),float)
> do it=0,dimsizes(time)-1
> zsfc(it,:,:)=topo
> end do
> copy_VarCoords(ps,zsfc)
> t=t*(1.+0.61*q) ; virtual T
> copy_VarCoords(q,t)
>
> p=new((/dimsizes(time),dimsizes(coefa),nlat,nlon/),float)
> do i=0,dimsizes(coefa)-1
> p(:,i,:,:)=doubletofloat(coefa(i))*p0+doubletofloat(coefb(i))*ps
> end do
> copy_VarCoords(t,p) ; suppose to be hPa
>
> z=p(time|:,lat|:,lon|:,lev|::-1)
> z=hydro(p(time|:,lat|:,lon|:,lev|::-1),t(time|:,lat|:,lon|:,lev|::-1),zsfc)
> z=z(:,:,:,::-1)
>
> p1=p(time|:,lat|:,lon|:,lev|:)
> h500=int2p(p1,z,500.,2)
> h500_less=h500(:,:,:,0)
> copy_VarCoords(ps,h500_less)
> v=h500_less(lat|:,lon|:,time|:)
> data(iy,im,:,:)=dim_avg_Wrap(v)
>
> delete(time)
> delete(a)
> delete(b)
> delete(c)
> delete(q)
> delete(ps)
> delete(t)
> delete(zsfc)
> delete(p)
> delete(z)
> delete(p1)
> delete(h500)
> delete(h500_less)
> delete(v)
> delete(w)
>
> end do
> end do
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Received on Fri Mar 8 08:05:53 2013