[ncl-talk] Dealing with 2D lat and lon outputs of WRF

[Prashanth Bhalachandran]

Dear NCL'ers,
I have a question on dealing with the 2D lat and long variables from WRF
output. For example, in my code below, I am having trouble using the lat
long information to either use them as coordinate variables or to be used
as inputs to the horizontal gradient function. What is the best way to
create or extract 1D lat and long information so that I can use them here?

Thank you,
Prashanth

begin


a = addfile("wrfout_d04_2005-07-29_12:06:00","r")


ctt = wrf_user_getvar(a,"ctt",-1) ; Cloud top temperatures in degree Celsius

lat = wrf_user_getvar(a,"XLAT",-1)

lon = wrf_user_getvar(a,"XLONG",-1)


;Original Dimensions and sizes: [Time | 10] x [south_north | 480] x
[west_east | 480]


; Take the horizontal gradient

  cttLatLon  = grad_latlon_cfd (ctt, lat, lon, False, False)


  ctt_grad_lat  = gradLatLon[0]    ; Extract Individual gradients in
latitudinal direction

  ctt_grad_lon  = gradLatLon[1]    ; Gradient in longitudinal directional


  delete(cttLatLon)


   if(all(ismissing(ctt_grad_lat))) then

    print("ctt_grad_lat contains all missing values, cannot continue.")

    return

  end if


    if(all(ismissing(ctt_grad_lon))) then

    print("ctt_grad_lon contains all missing values, cannot continue.")

    return

  end if
end


Output:

I can't prescribe lat and lon as coordinate variables since they are 2D.

$ ncl -n -Q cloud_top.ncl

fatal:Coordinate variables must have one dimension only

fatal:No coordinate variable exists for dimension (lat) in variable (ctt)

fatal:["Execute.c":8637]:Execute: Error occurred at or near line 12 in file
cloud_top.ncl


or use them as inputs to the gradient function:

$ ncl -n -Q cloud_top.ncl

fatal:Number of dimensions in parameter (1) of (grad_latlon_cfd) is (3),
(1) dimensions were expected

fatal:["Execute.c":8637]:Execute: Error occurred at or near line 12 in file
cloud_top.ncl
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