Re: [ferret_users] manipulation of netcdf file

[saurabh rathore <rohitsrb2020@xxxxxxxxx>]

Dear Ansley,

That sounds superb because what I found while on voyage that the data collected from ship board adcp, ctd, etc. are easily readable in Matlab and python in any format. But in pyferret or ferret it is not that easy to handle the format like .csv, .mat etc and one need a netcdf file that should be properly arranged for analysis. 

I believe building community of ferret/pyferret will provide a good handle to on such voyage collected data and initially processed data into netcdf using Matlab.

Cheers Saurabh

On Sat, Nov 3, 2018, 3:58 AM Ansley C. Manke <ansley.b.manke@xxxxxxxx wrote:

Hi,

Yes, in Pyferret/Ferret development we are working on enhancements for working with discrete sampling geometries data.  We've chosen to work first with the "Contiguous Ragged Array"representation. Examples of these file types can be found here: https://data.nodc.noaa.gov/thredds/catalog/example/v2.0/catalog.html

These files can be used now in Ferret, but there is much more we'd like to do than the current capabilities allow.  In a future release of PyFerret, you will be able to point to such a file and make plots of those native data types, such as a collection of time series for several stations; or a set of profiles or ship tracks.  We will be adding capabilities for sampling data from a gridded dataset to compare with discrete data, and also capabilities for putting sampled data into grids. 

Ansley

On 11/1/2018 6:03 PM, Russ Fiedler wrote:

Hi Saurabh,

Have a look here

http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/cf-conventions.html#discrete-sampling-geometries

You have the case of 'trajectoryProfile'

http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/cf-conventions.html#trajectory-profiles

Example H.21 corresponds to your case (substitute 'depth' for 'alt')

If depth is the same for all you can use a coordinate variable as explained at the end of the example.

'The pressure(p,o), temperature(p,o), and humidity(p,o) data for element o of profile p are associated with the coordinate values time(p), alt(p,o), lat(p), and lon(p). If all the profiles have the same set of vertical coordinates, the vertical auxiliary coordinate variable could be one-dimensional alt(z), or replaced by a one-dimensional coordinate variable z(z), provided the values are ordered monotonically. In the latter case, listing the vertical coordinate variable in the coordinates attribute is optional.'

z isn't Ferret friendly as a coordinate name so just use 'depth' directly if that is the case.

Cheers,

Russ

On 2/11/18 11:19 am, saurabh rathore wrote:

Dear Ferreters,

As currently in am working on creating netcdf file that I have received from Matlab processing. I can't upload the file as I am not allowed to do so. But I can show how this Matlab processed netcdf file is arranged.

currently SET data sets:
    1> ./adpc.nc  (default)
 name     title                                         I         J         K         L
 LON      Longitude                                ...       ...       ...       1:4503
 LAT      Latitude                                   ...       ...       ...       1:4503
 DEPTH    Depth                                   ...       ...       1:60      1:4503
 U        Zonal velocity component           ...       ...       1:60      1:4503
 V        Meridional velocity component    ...       ...       1:60      1:4503

list/l=1:10 lon,lat
             DATA SET: ./adpc.nc
             TIME: 16-OCT-2018 06:10 to 16-OCT-2018 07:00
 Column  1: LON is Longitude (degrees_east)
 Column  2: LAT is Latitude (degrees_north)
                                          LON    LAT
16-OCT-2018 06:13:19 /  1:  147.4 -42.99
16-OCT-2018 06:18:18 /  2:  147.4 -43.01
16-OCT-2018 06:23:17 /  3:  147.4 -43.03
16-OCT-2018 06:28:18 /  4:  147.4 -43.04
16-OCT-2018 06:33:19 /  5:  147.4 -43.06
16-OCT-2018 06:38:18 /  6:  147.4 -43.07
16-OCT-2018 06:43:18 /  7:  147.4 -43.09
16-OCT-2018 06:48:18 /  8:  147.4 -43.10
16-OCT-2018 06:53:18 /  9:  147.4 -43.12
16-OCT-2018 06:58:18 / 10:  147.4 -43.13

list/l=1 depth
             VARIABLE : Depth (meter)
             FILENAME : adpc.nc
             SUBSET   : 60 points (Z)
             TIME     : 16-OCT-2018 06:13
 1    /  1:   18.0
 2    /  2:   26.0
 3    /  3:   34.0
 4    /  4:   42.0
 5    /  5:   50.0
 6    /  6:   58.0
 ......................

 ......................

 .....................

 57   / 57:  466.0
 58   / 58:  474.0
 59   / 59:  482.0
 60   / 60:  490.0

list/l=1:10/k=1 u,v
             DATA SET: ./adpc.nc
             TIME: 16-OCT-2018 06:10 to 16-OCT-2018 07:00
             Z: 1
 Column  1: U is Zonal velocity component (meter second-1)
 Column  2: V is Meridional velocity component (meter second-1)
                                            U     V
16-OCT-2018 06:13:19 /  1:    ....    ....
16-OCT-2018 06:18:18 /  2:    ....    ....
16-OCT-2018 06:23:17 /  3:    ....    ....
16-OCT-2018 06:28:18 /  4:    ....    ....
16-OCT-2018 06:33:19 /  5:  0.1239 -0.7289
16-OCT-2018 06:38:18 /  6:  0.1832 -0.4678
16-OCT-2018 06:43:18 /  7:    ....    ....
16-OCT-2018 06:48:18 /  8:    ....    ....
16-OCT-2018 06:53:18 /  9:    ....    ....
16-OCT-2018 06:58:18 / 10: -0.0560 -0.0276

so how to make a proper structured netcdf file from this information ? It will be good example for me to process the data collected during any research voyage.

cheers, saurabh

--

REGARDS

Saurabh Rathore

Research Scholar (PhD.)

Centre For Oceans, Rivers, Atmosphere & Land Science Technology

Indian Institute Of Technology, Kharagpur

contact :- 91- 8345984434