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jayaram
9th May 2008, 09:00 AM
hi friends,

can any body suggest me how to append the ssh data (NetCDF). The data is given for individual days and it doesnt have a date / time axis in the netcdf data.. so when we want to do a time series analysis it is difficult. is there any means for adding the date in to that file. I tried ncdump and adding the time variable but its not coming in the exact dates but as t=1,2 like that..

thank u

rocksea
9th May 2008, 09:35 AM
are you familiar with ferret?

in ferret you can regrid a time axis like yours to form a real time axis.

something like this may do, for a variable 'var' from 1-jan-2000 to 31-dec-2007:

-----------
define axis/t = 1-jan-2000:31-dec-2007:1/units=days taxis
def grid/t = taxis tgrid
let new_var = var[gt=tgrid]
-----------

for the above, i hope you have a single file for all timesteps (dates) and not individual file for each timesteps. if you have individual file for each, you can join them using a descriptor file and then run the above detailed code. alternately, you can use cdo (climate data operators) to manipulate, merge etc for data files.

jayaram
9th May 2008, 05:26 PM
thank u for ur suggestion.. i will try. i know ferret and i tried the same way as u mentioned..anyways i will look again..

rocksea
14th May 2008, 01:30 PM
oops, you may need to try:

let new_var = var[gt=tgrid@asn]

azizpour
31st May 2008, 06:29 AM
hi
you can contact with Radar Altimeter Database System. their address is: http://rads.tudelft.nl/rads/rads.shtml
you can download your want from there, or contact with e.n.doornbos@tudelft.nl and want him that you need.
best regarded

yagnesh
9th August 2008, 12:39 PM
hi roxy..
i have little bit similar problem.. but i am new to ferret..
i have many nc files having sst data of specific region for data different days ..(random dates from 2000 to 2006).. can i make them together into one nc file....?

my files are all look like this
-----------------------------------------
yes? show data/full
currently SET data sets:
1> ./2004.0326.0521.noaa-16.sst.nc (default)

name title I J K L
SST SST 1:778 1:799 ... ...

on grid GQH1 with 0 for missing data
X=117.2E(117.2):127E(127) Y=33.2N:41.2N

yes?
----------------------------------------------
with in the nc file there is no time co ordinate information.. only file name is showing the time.. so i doubt we cannot make des file to read all files at once..

my problem is if i want calculate mean of some region (for example).,
i need to call the every file, make calculation(mean) and listing that value to file..

this is kind of difficult..
is there any easy way to do this..?

hope my question is clear..

rocksea
11th August 2008, 01:26 PM
hello yagnesh, without time co-ordinate information it may be difficult to join them into a single netcdf file. a possible way is to define a time axis for each sst, redefine the sst with the new time axis and save each file with its own time co-ordinate information. once that is done, it should be possible to combine them.

then once you have combined it, rest of the processing should be easy.


hi roxy..
i have little bit similar problem.. but i am new to ferret..
i have many nc files having sst data of specific region for data different days ..(random dates from 2000 to 2006).. can i make them together into one nc file....?

my files are all look like this
-----------------------------------------
yes? show data/full
currently SET data sets:
1> ./2004.0326.0521.noaa-16.sst.nc (default)

name title I J K L
SST SST 1:778 1:799 ... ...

on grid GQH1 with 0 for missing data
X=117.2E(117.2):127E(127) Y=33.2N:41.2N

yes?
----------------------------------------------
with in the nc file there is no time co ordinate information.. only file name is showing the time.. so i doubt we cannot make des file to read all files at once..

my problem is if i want calculate mean of some region (for example).,
i need to call the every file, make calculation(mean) and listing that value to file..

this is kind of difficult..
is there any easy way to do this..?

hope my question is clear..

jayakrishnanpr
27th July 2009, 11:52 AM
Hello,
I would like to combine the daily Quickscat files into monthly. I have tried it using CDO and NCO but does not work as there is no time axis. Is there any programs for the purpose..?? and how to combine them for time series analysis..??...Thank you...

rocksea
28th July 2009, 01:12 PM
Hello jayakrishnan, if you downloaded the quickscat data from ssmi.com, there are subroutines on the same website (http://www.ssmi.com/qscat/qscat_browse.html) at the following ftp section: ftp://ftp.ssmi.com/qscat/scatterometer_bmap_support/

These files will help you to read and process the files in fortran or matlab. I guess you are not talking about quickscat files which have been already converted to netcdf.

jayakrishnanpr
29th July 2009, 02:10 PM
Dear Roxy chetta,
I have downloaded the daily nc Quikscat files from the following ifremer site.

ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/mwf-quikscat/data/daily/2007/

The problem is with the data of this site. My problem is that if I have downloaded the 1.nc, 2.nc, 3.nc from this web site If I will combine using NCO or CDO the combined file is not having three different time steps....Is there any way to combine them using ferret..??. I am not much familiar to ferret....
Thanks a lot for your reply...I will check that link also....

rocksea
31st July 2009, 08:08 AM
Hello Jayakrishnan,

Have you checked the "settime" section of CDO?
If you have the CDO manual, on page 44, you have different options for setting a time axis for your data. There are examples in page 45 for setting the time axis.

So I guess after you combine the files, you can do the above and get the desired results.

Haven't done this myself so please check and inform back.

sivamtech
4th August 2009, 10:32 AM
Hi jayaram,

I assume you are using AVISO Delayed time UPD SLA..
If so, the attached jnl will assign time axis for each individual .nc file (Inferring Time from the filename itself) and it will save the data in a single nc file..

Go through the Jnl for usage/INSTRUCTIONS......

If your product is not DT UPD SLA, A slight Modification to the JNL will solve your problem.....

I hope this JNL will be usefull to YAGNESH also...............

Regards


thank u for ur suggestion.. i will try. i know ferret and i tried the same way as u mentioned..anyways i will look again..

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