[ncl-talk] Getting time series from several files in ncl

Mon Apr 20 05:56:56 MDT 2020

 Thanks I have looked at examples of wrf_user_ll_to_ij, It does not help. Let me clarify two things1. I used tc just to test that I can at least access tc, but that syntax does not give me tc at a specific location.2. When I talk of a specific location, I do not need interpolation. I know WRF will give me the value at the nearest grid location. That is enough for me. My core problem is: how do I put it to get one value, instead of the whole grid?

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wrf_user_ll_to_ij

NCL WRFUserARW.ncl functions (lat/lon functions)
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    On Monday, April 20, 2020, 12:02:28 PM GMT+2, Barry Lynn <barry.h.lynn at gmail.com> wrote:  

 If you know when these values occur within the time series, then you can index them quite easily.
Why don't you use wrf_user_getvar and then the wrf interpolation program.
If you want them at a specific point, I think you know how to do this.  There is also a get location program
https://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_ll_to_ij.shtml

Barry
On Mon, Apr 20, 2020 at 11:55 AM zilore mumba <zmumba at yahoo.com> wrote:

 Barry,My intention is to have RH and U, V time series. That's what I had in mind when I put 48. T2 only has time, lon ,lat. I have several daily output files, and I want an n-day series of 48 hour forecasts of T2

    On Monday, April 20, 2020, 8:00:41 AM GMT+2, Barry Lynn <barry.h.lynn at gmail.com> wrote:  

 Zilore:
T2 is a three dimensional variable.  Also, T2 is the two meter temperature. 
You want tc or tk (see: https://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_getvar.shtml).
Could you please explain how you are interpolating to 850 mb?  There is a WRF program to do this, and I am not sure how the indexing you are using works. How are you indexing the 48 time slot?  WRF has a program to list times, and you can match the time you want to the listed times to find the index.
Barry
On Mon, Apr 20, 2020 at 8:17 AM zilore mumba via ncl-talk <ncl-talk at ucar.edu> wrote:

 Sorry Rick I put in a surface variable T2 which only 3 coordinates, so I put "x = a[:]->T2(0,{-15},{30})". Now I am getting error of coordinates west-east and south-north not having  associated coordinate variables. I have seen this error before. I will find out how to get out of it 

    On Sunday, April 19, 2020, 11:53:33 PM GMT+2, Rick Brownrigg <brownrig at ucar.edu> wrote:  

 Perhaps do a printVarSummary(a[0]->T2)  ; it sounds like its not the shape you think it might/should be; i.e. 3D vs 4D

On Sun, Apr 19, 2020 at 3:29 PM zilore mumba <zmumba at yahoo.com> wrote:

    On Sunday, April 19, 2020, 11:27:47 PM GMT+2, zilore mumba <zmumba at yahoo.com> wrote:  

  Thanks Rick, that is close. The error am getting now is: fatal:Number of subscripts on rhs do not match number of dimensions of aggregated cat type variable, (4) Subscripts used, (3) Subscripts expected

    On Sunday, April 19, 2020, 10:17:12 PM GMT+2, Rick Brownrigg <brownrig at ucar.edu> wrote:  

 HI Zilore,
I think the issue is that addfiles() return a *list* of filevars, where addfile returns a single filevar.  Lists are indexed with [ ] notation; perhaps something like this will work:
  x = a[:]->T2(0,{850},{-15},{30})
Rick

On Sun, Apr 19, 2020 at 1:54 PM zilore mumba via ncl-talk <ncl-talk at ucar.edu> wrote:

I am trying to get time series at given locations from several WRF output files, e.g. 48H forecast temperature at 850hPa. Each file contains a day's model run. I have used ncl for years by adapting existing scripts, without really understanding. One issue I have difficulty with is getting variables from a file, especially WRF output.I thought the script to get a time series at 15S, 30E would be as simple as the one below. I am able to print the varsummary, but printing x tells me that "a is not a valid file reference.I would appreciate ant assistance.begin
files = systemfunc("ls -1 data/wrfout_d01_2020*") + ".nc"
  a = addfiles(files,"r")

  ListSetType (a, "cat")          ; concatenate (=default)
  tc = wrf_user_getvar(a,"tc",0)
  printVarSummary (tc)

  x = a->T2(0,{850},{-15},{30})
  asciiwrite("outfile.txt",x)
end

Zilore Mumba
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-- 
Barry H. Lynn, Ph.DSenior Associate Scientist, Lecturer,The Institute of the Earth Science, 
The Hebrew University of Jerusalem, 
Givat Ram, Jerusalem 91904, Israel 
Tel: 972 547 231 170
Fax: (972)-25662581
C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525

-- 
Barry H. Lynn, Ph.DSenior Associate Scientist, Lecturer,The Institute of the Earth Science, 
The Hebrew University of Jerusalem, 
Givat Ram, Jerusalem 91904, Israel 
Tel: 972 547 231 170
Fax: (972)-25662581
C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525

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