[ncl-talk] calculate a variable from other wrf variables and plot it

[Agud Pique, Enric]

Hello people,

I would like to plot a variable calculated from several wrf variables....for example, the following code....get temperature, pressure and relative humidity and after I select tempC and relhum in 850 hPa... after calculate Theta E, I want to plot it, but when I execute the scripts it fails...what is wrong?

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
begin
a = addfile("./wrfout_d01_2016-05-24_18:00:00","r")
wks = gsn_open_wks("X11","plt_Surface")


tc = wrf_user_getvar(a,"tc",0)
p = wrf_user_getvar(a,"pressure",0)
rh = wrf_user_getvar(a,"rh",0)
pressure = 850.
res = True

tempC = wrf_user_intrp3d(tc,p,"h",850.,0.,res)
relhum= wrf_user_intrp3d(rh,p,"h",850.,0.,res)

pltres = True
mpres = True

opts = res
opts at cnFillOn = True
opts at cnLevelSelectionMode = "ExplicitLevels"

;-----------------------------------------
; Calculate Theta E
;-----------------------------------------


undef("calc_thetae")

function calc_thetae(tempC,pres,relhum)

local tempC, pres, relhum, tc, tk, pp, p0, rh, es, en, rv, rd, cp, kd, td, tl, thetal, thetae

begin
pres = 850.
Tc = tempC                                                          ; [C]
tk = tempC+273.15                                                   ; [K]
pp = pres                        ; [hPa]
p0 = 1000                                        ; [hPa]
rh = relhum/100                          ; [no dimensions]
es = 6.112*exp(17.67*Tc/(Tc+243.5))                  ; [hPa]
en = rh*es                                       ; [hPa]
rv = 0.622*en/(pp-en)                  ; [no dimensions]
rd = 287.04                          ; [J/kgK]
cp = 1005.7                                    ; [J/kgK]
kd = rd/cp                                 ; [no dimensions]
tl = (1/((1/(tk-55))-(log(rh)/2840)))+55                 ; [K]
thetal = tk*((p0/(pp-en))^kd)*((tk/tl)^(0.28*rv))        ; [K]
thetae = thetal*exp(((3036/tl)-1.78)*rv*(1+0.448*rv))    ; [K]
thetae = thetae-273.15                                              ; [C]
return(thetae)
end

contour_t2 = wrf_contour(a,wks,thetae,opts)

plot= wrf_map_overlays(a,wks,(/contour_t2/),pltres ,mpres)

end

Best

Enric
De: Agud Pique, Enric
Enviat: dimarts, 24 / maig / 2016 21:17
Per a: ncl-talk at ucar.edu
Tema: get some variables from wrf output

Hello people,

I would like to use wrf_user_getvar or another function in order to get from a wrf filet he following variables:

Temperature on 850 hPa-Level in ºC,
Geopotential height on 850 hPa-Level
Relative humidity on 850 hPa-Level

I know how to get the temperature on T2
T2 = wrf_user_getvar(a,"T2",0)
where a is the wrf file...but in 850hPa?

Thank you
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