[ncl-talk] Adding time coordinate

[Dave Allured - NOAA Affiliate]

Sure, one netcdf file per day, 1 km grid.  But simple application of the
cd_inv_calendar function only gets you a long 1-D array of exact times.  It
is not sufficient to determine the structure of the desired result file.

This still leaves the question of how you want to carry the time-of-day
information inside that one file.  The related questions are, do you want a
2-D or 3-D array in the file, and what are the times of day on the third
dimension.  If the array is 3-D, then that means multiple grids within a
single day.  There are many examples of multiple grids per day in other
data sets, and they are almost always regularly spaced over time, such as
one grid per hour.

It is even possible to have a single data grid, and a companion grid that
has exact time of day at each grid point.  This would be unusual, but not
difficult.  Also, for this you would need to decide what to do about
multiple obs at the same grid point.

So forget the details of NCL for a minute.  Please describe specifically
the grid or grids that you would like, and their spacing across time of
day.  This will work any way you like, as long as you can fully describe
the shape of the desired end product.


On Tue, Jan 12, 2021 at 4:17 PM Vanúcia Schumacher <
vanucia-schumacher at hotmail.com> wrote:

> So, in fact what I need is just the hour and minute information, but the
> easiest way I found was to use the cd_inv_calendar function.
> How do you suggest that I can attach this information to the new_data
> variable?
> The purpose of the script is to spatialize the input data to a regular 1km
> grid.
> The input data is just one example of several data in which I use to
> generate a netcdf file per day with this script.
>
>
> ------------------------------
> *De:* Dave Allured - NOAA Affiliate <dave.allured at noaa.gov>
> *Enviado:* terça-feira, 12 de janeiro de 2021 16:39
> *Para:* Vanúcia Schumacher <vanucia-schumacher at hotmail.com>
> *Cc:* ncl-talk at ucar.edu <ncl-talk at ucar.edu>
> *Assunto:* Re: [ncl-talk] Adding time coordinate
>
> Okay.  It looks like your original dates and times are not regularly
> spaced, and you are trying to make a new set of time coordinates by setting
> seconds = 0.  This results in more irregular time values with some
> duplicate values, which are not legal for coordinate subscripting.  This is
> the error "Non-monotonic coordinate value".
>
> It looks like your input file spans all 24 hours in one day.  Can you
> please explain exactly what you want the new time coordinates to look
> like?  Are they regularly spaced or irregular?  Start and end times?
>
>
> On Tue, Jan 12, 2021 at 4:51 AM Vanúcia Schumacher <
> vanucia-schumacher at hotmail.com> wrote:
>
> Using your sugestion:
> ntimes = dimsizes(time)
> new_data = new((/nlat,mlon,ntimes/),"float")
> I got this error:
> fatal:NclOneDValGetClosestIndex: Non-monotonic coordinate value being
> used, can't complete coordinate subscript
> fatal:Could not obtain coordinate indexes, unable to perform subscript
> fatal:["Execute.c":8640]:Execute: Error occurred at or near line 89 in
> file test.ncl
> The line 89:   new_data({lat(i)},{lon(i)},{time(i)}) =
> new_data({lat(i)},{lon(i)},{time(i)})+(/var(i)/)
>
> Using this:
> ntimes = dimsizes(time(1))
> new_data = new((/nlat,mlon,ntimes/),"float")
> I got this error:
> fatal:Coordinate variables must be the same dimension as their dimension
> fatal:No coordinate variable exists for dimension (time) in variable
> (new_data)
> fatal:["Execute.c":8637]:Execute: Error occurred at or near line 86 in
> file test.ncl
> The line 86: new_data&time     = time
>
> Attached is the script and a test data.
> Thanks
> ------------------------------
> *De:* Dave Allured - NOAA Affiliate <dave.allured at noaa.gov>
> *Enviado:* segunda-feira, 11 de janeiro de 2021 22:55
> *Para:* Vanúcia Schumacher <vanucia-schumacher at hotmail.com>
> *Cc:* ncl-talk at ucar.edu <ncl-talk at ucar.edu>
> *Assunto:* Re: [ncl-talk] Adding time coordinate
>
> Please show the complete text for line 75, the complete error message, and
> printVarSummary for the array new_data, just before line 75 is executed.
> Also please attach the current version of your script.  Thank you.
>
>
> On Mon, Jan 11, 2021 at 5:39 PM Vanúcia Schumacher <
> vanucia-schumacher at hotmail.com> wrote:
>
> Thanks for the help, but the error persists in the line 75
>
> PrintVarSummary:
>
> Variable: nlat
> Type: integer
> Total Size: 4 bytes
>             1 values
> Number of Dimensions: 1
> Dimensions and sizes: [1]
> Coordinates:
>
> Variable: mlon
> Type: integer
> Total Size: 4 bytes
>             1 values
> Number of Dimensions: 1
> Dimensions and sizes: [1]
> Coordinates:
>
> Variable: ntimes
> Type: integer
> Total Size: 4 bytes
>             1 values
> Number of Dimensions: 1
> Dimensions and sizes: [1]
> Coordinates:
> (0) 6024
>
> *De:* Dave Allured - NOAA Affiliate <dave.allured at noaa.gov>
> *Enviado:* segunda-feira, 11 de janeiro de 2021 20:27
> *Para:* Vanúcia Schumacher <vanucia-schumacher at hotmail.com>
> *Cc:* ncl-talk at ucar.edu <ncl-talk at ucar.edu>
> *Assunto:* Re: [ncl-talk] Adding time coordinate
>
> Your script looks pretty good so far.  This does not look right:
>     new_data = new((/nlat,mlon,toint(time(1))/),"float")
>
> Try this:
>     ntimes = dimsizes (time)
>     new_data = new((/nlat,mlon,ntimes/),"float")
>
> Always use printVarSummary when you are having problems with arrays; and
> look at dimensions, coordinates, attributes, and such.
>
> Also, in the future, please show the *first* error received, and be sure
> to show exactly which line it occurs on.  Usually the first error causes
> more problems later, and it is harder to sort out.  I am not sure what
> happened this time, but that does not matter now.  Good luck.
>
>
> On Mon, Jan 11, 2021 at 2:51 PM Vanúcia Schumacher via ncl-talk <
> ncl-talk at mailman.ucar.edu> wrote:
>
> Hi users,
>
> I need to add the time information (preference in hh and mn) extracted
> from an ascii file to a new variable (new_data from script), but I am not
> having success.
> Attached is the script I am trying using the function cd_inv_calendar and
> the error obtained:
> fatal:No coordinate variable exists for dimension (time) in variable
> (new_data)
>
> I appreciate some help to attach this information to my new variable
>
>
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