Re: [ferret_users] How can I produce a time series of JJA averages (orother intervals) from a monthly time series?

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

Hi All,
Jaison's exactly right, but in Ferret v6.0 we can control what 
attributes are written to netcdf files -- to remove an attribute that 
would otherwise be written, just issue a CANCEL ATTRIBUTE/OUTPUT command

  yes? cancel attribute/output  my_var.attributename

To see all the attributes that a variable has

  yes? sho attribute/all my_var

or to see the "output" flags

  yes? show attribute/all/output my_var

Ansley



Jaison Kurian wrote:
> Hi Yun,
>         Recent versions of Ferret write two attributes for a variable
> (when saved to a NetCDF file) called "long_name" and "long_name_mod"
> and the extra title you complainted comes from the NetCDF attribute
> "long_name_mod". This information is usefull sometimes and there is 
> no need to worry about this. If you want to remove it from the default
> plot title, then define a new variable and assign the title you want.
> Or if you want to remove it from the NetCDF file, you have to use some
> NetCDF editing tools....or write it first to an intermediate file, read
> it back and assign a new variable name and title to it, then save to the
> final destination file. As far as i know, nothing can be done while
> saving data in NetCDF format from Ferret.
>
> Also please have a look at these mails in the archive:
>
> http://ferret.wrc.noaa.gov/Ferret/Mail_Archives/fu_2004/msg00018.html
> http://www.ferret.noaa.gov/Ferret/Mail_Archives/fu_2004/msg00667.html
>
> Hope this helps,
>
> Jaison
>
> On Wed, 20 Sep 2006 Yun.Li@csiro.au wrote:
>
>   
> > Hi Jaison,
> >
> >  
> > Thanks for your help. The example is very useful. I have obtained a
> > solution to my problem following the lines of the example. 
> >  
> > A minor question is why the extra item "(X=18.8E:18.8E(378.8),
> > Y=91.3S:91.3N)" appears in the title of new variable UWND_JJA (see
> > following lines). 
> >  
> > yes? use uwnd_jja_mean.nc
> >
> > yes? show data
> >
> >      currently SET data sets:
> >
> >     1> .\uwnd_jja_mean.nc  (default)
> >
> >  name     title                             I         J         K
> > L
> >
> >  UWND_JJA JJA Seasonal Mean UWND           1:144     1:73      ...
> > 1:11
> >
> >        (X=18.8E:18.8E(378.8), Y=91.3S:91.3N)
> >
> >  
> >  
> > This extra item "(X=18.8E:18.8E(378.8), Y=91.3S:91.3N)" also appeared in
> > my SLP_JJA case. How can I remove it?
> >
> >  
> > Best regards,
> >
> >  
> > Yun
> >
> >  
> > -----Original Message-----
> > From: Jaison Kurian [mailto:jaison@caos.iisc.ernet.in] 
> > Sent: Wednesday, 20 September 2006 4:16 PM
> > To: Li, Yun (CMIS, Floreat)
> > Cc: Ansley.B.Manke@noaa.gov; oar.pmel.ferret_users@noaa.gov
> > Subject: RE: [ferret_users] How can I produce a time series of JJA
> > averages (or other intervals) from a monthly time series?
> >
> >  
> > Hi Yun,
> >
> >         Here is an example using monthly_navy_winds dataset.
> >
> > Also see these two mails, which deals with somewhat similar
> >
> > questions :
> >
> >  
> > http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2004/msg00575.html
> >
> > http://www.ferret.noaa.gov/Ferret/Mail_Archives/fu_2005/msg00018.html
> >
> >  
> > Hope this helps...
> >
> >  
> > Jaison
> >
> >  
> >  
> > !-------Example : JJA seasonal mean from monthly data-----------
> >
> > !
> >
> > \ cancel mode verify
> >
> > ! Drawbacks : Data should start at January of a year. Otherwise
> >
> > !             "yr_months" variable should be modified accordingly. 
> > !
> >
> > ! monthly navy winds : 16-JAN-1982 to 17-DEC-1992
> >
> > !-----------------------------------------------------------
> >
> >  
> >      use monthly_navy_winds
> >
> >  
> >      ! create a mask such that only JJA is valid and all other months
> >
> >      !    are set to missing value
> >
> >  
> >      let L_indx    = L[GT=uwnd]
> >
> >      let yr_months = L_indx- 12*INT((L_indx-1)/12) 
> >      list yr_months
> >
> >  
> >      ! JJA -->  L is 6-8
> >
> >  
> >      let mask_other_months = IF yr_months GT 5 AND yr_months LT 9 THEN 1
> >
> >      list yr_months, mask_other_months
> >
> >  
> >      ! Apply the mask
> >
> >  
> >      let uwnd_masked = uwnd[d=1] * mask_other_months
> >
> >      list/x=60/y=10 uwnd_masked 
> >  
> >      ! Club the JJA values together
> >
> >  
> >      let uwnd_compr  = COMPRESSL(uwnd_masked)
> >
> >      list/x=60/y=10 uwnd_compr
> >
> >  
> >      ! 1982-1992 --> 11 years --> 11*3=33 data points
> >
> >      ! we need to average this data points in pairs of 3 to find the
> >
> >      !  seasonal mean. Easy way is to use two abstract axes, one
> >
> >      !  with 33 points (ranging from 1-33) and another one with
> >
> >      !  11 points (ranging from 2-32) and regrid using @AVE.
> >
> >  
> >      define axis/t=1:33:1 t33
> >
> >      let uwnd_jja_all = uwnd_compr[gt=t33@ASN] 
> >      list/x=60/y=10 uwnd_jja_all
> >
> >  
> >      define axis/t=2:32:3 t11  ! for the exact seasonal mean
> >
> >      let uwnd_jja_av  = uwnd_jja_all[gt=t11@AVE]
> >
> >  
> >      ! now assign a proper yearly time axis defined over 1982-1992
> >
> >      !  here we dont need any interpolation but the grid change
> >
> >      !  ..so use @ASN regridding
> >
> >  
> >      define axis/t=1982:1992:1/units=years tyear
> >
> >      let uwnd_jja  = uwnd_jja_av[gt=tyear@ASN]
> >
> >      list/x=60/y=10 uwnd_jja ! 6.36 7.99 7.12  8.51 9.46 9.32
> >
> >      set var/title="JJA Seasonal Mean UWND"/units="m/s" uwnd_jja
> >
> >      
> >      ! save to a NetCDF file for future use
> >
> >  
> >      ! sp rm -f uwnd_jja_mean.nc
> >
> >      ! save/file=uwnd_jja_mean.nc/APPEND uwnd_jja
> >
> >  
> > !-------------end of example-------------------------------------
> >
> >  
> >  
> > On Wed, 20 Sep 2006 Yun.Li@csiro.au wrote:
> >
> >  
> >     
> > > Hi Ansley,
> > >       
> > >  
> > >       
> > > I am trying to do "Leaving only JJA SLP data" from a monthly NCEP SLP
> > >       
> > > data "slp.mon.mean.nc". I have looked at
> > >       
> > > http://ferret.pmel.noaa.gov/Ferret/FAQ/analysis/seasonal_masking.html.
> > >       
> > > But I could not get a solution because of my poor ferret skills.
> > >       
> > Could
> >
> >     
> > > you please give me a help here?
> > >       
> > >  
> > >       
> > > Thanks,
> > >       
> > >  
> > >       
> > >  
> > >       
> > > Yun
> > >       
> > >  
> > >       
> > >  
> > >       
> > >  
> > >       
> > >   _____  
> > >       
> > > From: Ansley Manke [mailto:Ansley.B.Manke@noaa.gov] 
> > >       
> > > Sent: Wednesday, 20 September 2006 3:02 AM
> > >       
> > > To: Li, Yun (CMIS, Floreat)
> > >       
> > > Cc: oar.pmel.ferret_users@noaa.gov
> > >       
> > > Subject: Re: [ferret_users] How can I produce a time series of JJA
> > >       
> > > averages (or other intervals) from a monthly time series?
> > >       
> > >  
> > >       
> > > Hi Yun,
> > >       
> > > Here are a couple of FAQ's for you to look at - if one of these is the
> > >       
> > > kind of thing you want to do. If you need help applying the ideas,
> > >       
> > > please write back to the users list.
> > >       
> > > This FAQ makes a "seasonal mask" to pick out data from part of each
> > >       
> > > year.  It does the problem with units of time in days; but if you're
> > >       
> > > starting with monthly data you could do a similar thing with months,
> > >       
> > > with JJA being months 6,7,8.  You could combine this with the COMPRESS
> > >       
> > > functions to remove the missing data and leave only the JJA data.
> > >       
> > > http://ferret.pmel.noaa.gov/Ferret/FAQ/analysis/seasonal_masking.html
> > >       
> > > Or, did you have in mind a climatology, averaging all of the JJA data
> > >       
> > > for all years, and returning just one point?  In that case, see
> > >       
> > > "climatology, creating" in the Users Guide, and this FAQ for more
> > >       
> > > examples
> > >       
> > > http://ferret.pmel.noaa.gov/Ferret/FAQ/analysis/climatologies.html
> > >       
> > > Ansley
> > >       
> > > Yun.Li@csiro.au wrote: 
> > >       
> > > Dear Ferreters,
> > >       
> > >  
> > >       
> > > I am trying to produce a seasonal time series (such as JJA time
> > >       
> > series)
> >
> >     
> > > from a monthly time series. 
> > >       
> > >  
> > >       
> > > There is an example from the Ferret FAQ on "How can I produce a time
> > >       
> > > series of annual averages (or other intervals) from a monthly time
> > >       
> > > series?"
> > >       
> > >  
> > >       
> > http://ferret.wrc.noaa.gov/Ferret/FAQ/analysis/annual_from_monthly.html
> >
> >     
> > >  
> > >       
> > > I would be most grateful if you can let me know how to produce a
> > >       
> > > seasonal averaged time series (such as June-July-August average time
> > >       
> > > series) from a monthly time series by modifying the code used to
> > >       
> > produce
> >
> >     
> > > annual time series in the above web page, that is,
> > >       
> > >  
> > >       
> > >      yes?  SET DATA monthly_navy_winds
> > >       
> > >      yes?  DEFINE AXIS/EDGES/T0=1-jan-1900/UNITS=days tann82_92 =
> > >       
> > > DAYS1900(X[i=1982:1993:1],1,1)
> > >       
> > >      yes?  PLOT/X=180/Y=0 uwnd
> > >       
> > >      yes?  PLOT/X=180/Y=0/over uwnd[gt=tann82_92@ave]     ! the above
> > >       
> > > plot 
> > >       
> > >  
> > >       
> > >  
> > >       
> > >  
> > >       
> > > Thanks, 
> > >       
> > >  
> > >       
> > > Yun Li
> > >       
> > > CSIRO, Australia
> > >       
> >     
--

~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~> 
Ansley Manke, NOAA/PMEL   ansley.b.manke@noaa.gov
7600 Sand Point Way NE, Seattle WA
Phone 206-526-6246,  FAX 206-526-6744