[ncl-talk] Define and populate plev_bnds in NetCDF
Dennis Shea
shea at ucar.edu
Sat Oct 24 08:52:14 MDT 2015
The
typeof(plev) => ....
was part of my email to indicate that the code following was for
double. It was not part of the NCL script. That was unclear ....
sorry.
Also, the 'plev' variable is just a place-holder for the name of the
variable to which you want to associate the 'plev_bounds' variable.
So, if the variable requiring a bounds associated variable was named
(say) 'level', all of the 'plev' would be changed to 'level'
(plev_bnds ===> level_bnds)
==
Also, does the original variable have a "units" attribute? If so, the
following would be useful though not required
plev_bnds at units = "hPa"
or
plev_bnds at units = "Pa"
or
plev_bnds at units = "..."
I have set it as "Pa"
D
On Sat, Oct 24, 2015 at 8:15 AM, Hertz, Judith A.
(GSFC-606.0)[INTERNATIONAL TECHNOLOGY COALITION, INC]
<judith.a.hertz at nasa.gov> wrote:
> Hi Dennis,
>
> Thanks so much for your replies. I’ve read through these scripts and some
> docs, here’s what I’ve tried:
>
> ;=============================================================
> ; https://www.ncl.ucar.edu/Applications/method_1.shtml
> ;=============================================================
> typeof(plev) => double
>
> plev_bnds = (/ (/ 100000, 98750/) \
> , (/ 98750, 96250/) \
> , (/ 91250, 88750/) \
> , (/ 1000, 500/) /) *1d0 ; last line
>
> ; name dimensions using NCL syntax
> plev_bnds!0 = "bnds0" ; ... whatever is appropriate
> plev_bnds!1 = "bnds1"
> if (isatt(plev_bnds,"units")) then
> plev_bnds at units = plev at units
> end if
> printVarSummary(plev_bnds)
>
> dirNc = "./"
> filNc = "plev_bnds.nc"
> pthNc = dirNc+filNc
>
> system("/bin/rm -f "+pthNc) ; remove any pre-existing file
> ncdf = addfile(pthNc ,"c") ; open output netCDF file
>
> ;===================================================================
> ; create global attributes of the file (optional)
> ;===================================================================
> fAtt = True ; assign file attributes
> fAtt at title = "plev bound file"
> fAtt at Conventions = "None"
> fAtt at creation_date = systemfunc ("date")
> fileattdef( ncdf, fAtt ) ; copy file attributes
>
> ;===================================================================
> ; Write to file
> ;===================================================================
>
> ncdf->plev_bnds = plev_bnds
>
>
> But I’m getting an error on the size of the right hand dimension I can’t
> fix. Thanks in advance if you can help:
>
> Copyright (C) 1995-2015 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 6.3.0
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
> fatal:syntax error: typeof is a function not a procedure; return value must
> be referenced
> fatal:error at line 4 in file mk_plev_bnd.ncl
>
> fatal:syntax error: line 4 in file mk_plev_bnd.ncl before or near =
> typeof(plev) =
> ----------------^
>
> fatal:error in statement
>
> Variable: plev_bnds
> Type: double
> Total Size: 64 bytes
> 8 values
> Number of Dimensions: 2
> Dimensions and sizes: [bnds0 | 4] x [bnds1 | 2]
> Coordinates:
> fatal:Variable (bnds1) is undefined
> fatal:["Execute.c":8575]:Execute: Error occurred at or near line 39 in file
> mk_plev_bnd.ncl
>
>
> judy
>
> On Oct 21, 2015, at 3:55 PM, Dennis Shea <shea at ucar.edu> wrote:
>
> Also .... another recommendation ...
>
> It is not required but I recommend the type of the 'plev_bnds' should
> be the same type as 'plev'
>
> =====================
> typeof(plev) => Integer
>
> plev_bnds = (/ (/ 100000, 98750/) \
> , (/ 98750, 96250/) \
> , (/ 91250, 88750/) \
> , (/ 1000, 500/) /) ; last line
> =================
> typeof(plev) => float
>
> plev_bnds = (/ (/ 100000.0, 98750.0/) \
> , (/ 98750.0, 96250.0/) \
> , (/ 91250.0, 88750.0/) \
> , (/ 1000.0, 500.0/) /) ; last line
>
> or, easier
>
> typeof(plev) => float
>
> plev_bnds = (/ (/ 100000, 98750/) \
> , (/ 98750, 96250/) \
> , (/ 91250, 88750/) \
> , (/ 1000, 500/) /) *1.0 ; last line
>
> =================
>
> typeof(plev) => double
>
> plev_bnds = (/ (/ 100000d0, 98750d0/) \
> , (/ 98750d0, 96250d0/) \
> , (/ 91250d0, 88750d0/) \
> , (/ 1000d0, 500d0/) /) ; last line
>
> or, easier
>
> typeof(plev) => double
>
> plev_bnds = (/ (/ 100000, 98750/) \
> , (/ 98750, 96250/) \
> , (/ 91250, 88750/) \
> , (/ 1000, 500/) /) *1d0 ; last line
>
>
> On Tue, Oct 20, 2015 at 4:30 PM, Dennis Shea <shea at ucar.edu> wrote:
>
> NCL .... A general place to go to get file IO information.
>
> Click 'Examples' .... then 'File I/O' .... Click 'Change netCDF file'
>
> For 'fun' look at other examples also.
>
> ===
>
>
> ===
>
> Two approaches:
>
> [1]
> If you are familiar withe the netCDF Operators (not associated with
> NCL). Use netCDF Operator: ncks [Use WWW to search for
> documentation]
>
> (a) Create a netCDF with the plev_bnds variable: plev_bnd.nc
> See attached script. Of, course the 'plev' should be changed
> to the appropriate variable name.
>
> (b) If 'foo.nc' is your base file:
> ncks -O plev.nc foo.nc
> will append the bounds variable to the file.
>
>
> [2] NCL direct
>
> plev_bnds = (/ (/100000, 98750/) \
> , (/ 98750, 96250/) \
> , (/ 91250, 88750/) \
>
> , (/ ... , ... /) /) ; last line
>
> ; name dimensions using NCL syntax
> plev_bnds!0 = "plev" ; ... whatever is appropriate
> plev_bnds!1 = "pbnd"
> plev_bnds at units = plev at units
> printVarSummary(plev_bnds)
>
>
> f = addfile("foo.nc", "w") ; NOTE the 'w'
> f->plev_bnds = plev_bnds
>
> ===
> Either way, I would create test files in case there is a problem.
>
> On Tue, Oct 20, 2015 at 12:44 PM, Hertz, Judith A.
> (GSFC-606.0)[INTERNATIONAL TECHNOLOGY COALITION, INC]
> <judith.a.hertz at nasa.gov> wrote:
>
> Greetings, NCL’ers
>
> I’m new to NCL. I want to add a variable, plev_bnds, to NetCDF files so
> that:
>
> double plev_bnds(plev, bnds) ;
>
> data:
>
> plev_bnds =
> 100000, 98750,
> 98750, 96250,
> 96250, 93750,
> 93750, 91250,
> 91250, 88750,…..
>
> I’ve found addfile, which looks to be a good way to populate the data but
> the docs say the variable must already exist. Do you know what is the NCL
> way to create/define a new variable?
>
> thanks,
>
> judy
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