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RE: [ferret_users] time interpolation - missing values

Title: RE: [ferret_users] time interpolation - missing values

Hi Ansley,

this was a great idea, but I don't know why, the 2 scripts are not working pretty well my my data. I tried make_des and nc2mc, but the resulting file as only 31 data on the time axis instead of 365 which I'd prefer...

Here's what I did with make_des:

fred@fred-laptop:~/Desktop/CMC_work/nc2multi$ ./make_des metfor.1998.*.nc > file.des
ncdump [-c|-h] [-v ...] [[-b|-f] [c|f]] [-l len] [-n name] [-p n[,n]] [-x] [-k] file
  [-c]             Coordinate variable data and header information
  [-h]             Header information only, no data
  [-v var1[,...]]  Data for variable(s) <var1>,... only
  [-b [c|f]]       Brief annotations for C or Fortran indices in data
  [-f [c|f]]       Full annotations for C or Fortran indices in data
  [-l len]         Line length maximum in data section (default 80)
  [-n name]        Name for netCDF (default derived from file name)
  [-p n[,n]]       Display floating-point values with less precision
  [-x]             Output XML (NcML) instead of CDL
  [-k]             Output kind of netCDF file
  file             Name of netCDF file
netcdf library version "3.6.2" of Feb  8 2008 16:40:20 $

Then if I look at file.des in ferret:

yes? use file
yes? show data
     currently SET data sets:
    1> ./file.des  (default)
 name     title                             I         J         K         L
 LON      longitude                        1:192     1:94      ...       ...
 LAT      latitude                         1:192     1:94      ...       ...
 MSL      Mean sea level pressure          1:192     1:94      ...       1:31
 P10U     10 metre U wind component        1:192     1:94      ...       1:31
 P10V     10 metre V wind component        1:192     1:94      ...       1:31
 P2T      2 metre temperature              1:192     1:94      ...       1:31
 SSRD     Surface solar radiation downwar  1:192     1:94      ...       1:31
 STRD     Surface thermal radiation downw  1:192     1:94      ...       1:31
 TP       Total precipitation              1:192     1:94      ...       1:31
 QH       2m Specific humidity             1:192     1:94      ...       1:31

yes? show grid msl
 name       axis              # pts   start                end
 X         LONGITUDE          192mr   0E                   1.875W
 Y         LATITUDE            94 i   88.541S              88.541N
 normal    Z
 TIME1     TIME                31 r   01-JAN 00:00         31-DEC-0059 13:12

There's clearly a problem with the time axis... Would it be because all the metfor* files have a different time origin (jan-01-1998 for metfor.1998.01.nc, feb-01-1998 for metfor.1998.02.nc, etc.)?

Is anybody has any cue?

-----Original Message-----
From: Ansley Manke [mailto:Ansley.B.Manke@xxxxxxxx]
Sent: Wed 5/20/2009 7:41 PM
To: Cyr Frederic
Cc: oar.pmel.ferret_users@xxxxxxxx
Subject: Re: [ferret_users] time interpolation - missing values

Hi Frederic,
You say you have one file for each month. That sounds as if you'd really
like to think of all of them together as a single dataset.  In the
example for January 1998 you show, what you want is the first daily
value from February 1998 to use in computing the 6-hour values of
january 31, hour 5, 12, and so forth, right? If this is the case, you
should create a multi-file dataset descriptor file for the monthly data,
define a 6-hour time axis for the whole time range, and do the
regridding to the 6-hour time axis in one step.

There are a couple of tools available for creating descriptor files if
your monthly data is in netCDF files.  Have a look at the section of the
Users Guide on descriptor files, 
and read down to the section called "tools for making descriptor files"
which will tell you where to get those tools and how to use them.


Frederic.Cyr@xxxxxxxxxx wrote:
> Hi everyone,
> here's a probably known problem, but I can't find a solution.
> To feed a model, I need a 6-hourly dataset of many variables, one file
> every months. For some variables, I only have daily values, and I want
> to interpolate the daily values on a 6-hourly grid that I have. The
> problem is as the daily grid is defined at 00:00 every day, there's no
> value for the last day (I would need the following day to continue the
> interpolation...)
> Here's an example for january 1998:
> yes? let msli = msl[gl=msl[d=1], d=2]  !MSL[d=2] is the daily and
> MSL[d=1] is the 6-hourly
> The problem is that the new variable as been defined for l=1:121, but
> is empty for l=122:124 (31day*4-times-a-day = 124 points)
> Any idea how to solve the problem?
> Thanks a lot anyway!
> Fred

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