Re: [ferret_users] question about define axis t

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Leandro

So, the input data don't include each and every longitude and latitude 
on the grid you have defined with xlon and ylat.  This means that you 
need to read the data on a single, long axis, and then call the 
regridding function as you have done.  The FILE command you used with 
/grid=mygrid assumes that all the locations are represented in your 
input file.

So, just define a long axis. If there were fewer than the  default 
abstract-axis length of 20480 points, you could do this without defining 
an axis at all (you'd just skip the /grid= qualifier), but you need a 
longer axis. Use the length of the dataset, or some number longer than 
its length.

yes? define axis/x=1:90000:1 xindex
yes? define grid/x=xindex xinput
yes? file=/skip=10000/FORM=free/grid=xinput/var="lon, lat, ..."

Then make the SCAT2GRIDGAUSS_XY calls with  arguments (lon, lat, var, 
x[gx=xlon], y[gy=ylat], ...)




On 3/21/2011 11:06 AM, Otacilio Leandro wrote:
> Hi Ansley,
>
> The data that i'm using is at a grid of 0.5 degree only over
> continental areas. Because of that i'm using the scat2gridgauss
> function.
>
> The data also is organized with lon and lat at the first and second
> columns and the months january until december at the columns 3-15. The
> last column is the anual average for the year.
>
> I'm seeding you the year of 1900 as exemple. My goal with this data is
> to create only one cdf file with all monthly means of surface
> temperature since 1900 until 2008. At this jnl script i'm trying to
> create one cdf file per month and then concatenet them all using NCO.
> If there's a simple way to this using ferret i'll apreciate if you
> enlighten me.
>
> Thank you again and continue the great job you are doing!
>
> 2011/3/21 Ansley Manke<Ansley.B.Manke@xxxxxxxx>:
> > hi-
> > I think that we need to find out how to read the data first.   Could you
> > send me a few lines from the start of your ascii file?
> >
> > After you run the commands
> >
> > define axis/x=-179.8:179.8:0.5/units=degrees xlon
> > define axis/y=-89.75:89.75:0.5/units=degrees ylat
> > define axis/t=1:1:1 axist
> > define grid/x=xlon/y=ylat/t=axist mygrid
> > file=/g=mygrid/skip=10000/FORM=free/var="lon, lat, var01, var02, var03,
> > var04, var05, var06, var07, var08, var09, var10, var11, var12, anual"
> > "air_temp2009/air_temp.$1"
> >
> > This sequence would indicate that your data is already on an XY grid, at one
> > value of time.  How do these plots look?
> >
> > yes? shade/L=1 lon
> > yes? shade/L=1 lat
> >
> > yes? shade var01
> >
> > If the data are are not already on a on the grid defined by xlon and ylat,
> > then the above FILE command is not the correct one to use.  If the data is
> > on a grid, then you don't need to call the scat2gridgauss function.
> >
> >
> > On 3/21/2011 4:36 AM, Otacilio Leandro wrote:
> > > Ansley,
> > >
> > > I've corrected the file line but still the problem continue. I'm
> > > atacching the jnl script so you can verify any others erros.
> > >
> > > Thank you very much.
> > >
> > > 2011/3/18 Ansley Manke<Ansley.B.Manke@xxxxxxxx>:
> > > > Hi -
> > > > In your FILE command, do you have quotes around the list of variable
> > > > names?
> > > >   It should look like,
> > > >
> > > > file=/g=mygrid/var="lon, lat, value01, value02, ..."  ascii_file.txt
> > > >
> > > >
> > > >
> > > > On 3/18/2011 8:29 AM, Otacilio Leandro wrote:
> > > > > Hello,
> > > > >
> > > > > I've got a data with 2D (x and y) climatological monthly temperature
> > > > > over continental areas and i got some trouble at using it on ferret.
> > > > > The data are separated by one file per year and i used the function
> > > > > scat2gridgauss_xy to correctly read the data over the continent.
> > > > > My goal with this data is create a cdf file varing at time (each
> > > > > "timestep" is one month of the data).
> > > > >
> > > > > I defined the axis this way:
> > > > >
> > > > > define axis/x=-179.8:179.8:0.5/units=degrees xlon
> > > > > define axis/y=-89.75:89.75:0.5/units=degrees ylat
> > > > > define axis/t=1:1:1 axist
> > > > >
> > > > > define grid/x=xlon/y=ylat/t=axist mygrid
> > > > >
> > > > > But when i used
> > > > >
> > > > > file=/g=mygrid/var= lon, lat, value01, value02 ... etc , ascii-file.txt
> > > > >
> > > > > all values of the orignal data are exchanged for 12.8 as you can see
> > > > > below.
> > > > >
> > > > > Here is the stat of my variable:
> > > > >
> > > > >              temp-1900-02
> > > > >              LONGITUDE: 179.9E(-180.1) to 179.9E(179.9)
> > > > >              LATITUDE: 90S to 90N
> > > > >              Z:  N/A
> > > > >              T: 1
> > > > >              DATA SET: air_temp2009/air_temp.1900
> > > > >
> > > > >   Total # of data points: 259200 (720*360*1*1)
> > > > >   # flagged as bad  data: 259194
> > > > >   Minimum value: 12.8
> > > > >   Maximum value: 12.8
> > > > >   Mean    value: 12.8 (unweighted average)
> > > > >   Standard deviation: 7.178999E-07
> > > > >
> > > > >
> > > > > I also tryed to regrid the variable using
> > > > >
> > > > > let temp = tmp[g=mygrid]
> > > > >
> > > > > but it also showed problems because the time axis is missing at temp
> > > > > variable.
> > > > >
> > > > > The way i defined the t axis is correct? The reason that i want a time
> > > > > axis on my variable is to use NCO to concatened all cdfs that im going
> > > > > to create. I tested using file without time axis and got an error from
> > > > > NCO.
> > > > >
> > > > > I'm using:
> > > > >
> > > > >         FERRET v6.64
> > > > >         Linux rh5 (gfortran) 2.6.18-164.11.1.el5 - 09/20/10
> > > > >
> > > > > Thanks for the help.