regeneration of netcdf

[ecco-group]

regeneration of netcdf

[owang01]

@ifenty

The sIceLoad snapshots can be simply calculated by summing SIheff and SIsnow snapshots (weighted by their own density). Both SIheff and SIsnow snapshots are available https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/nctiles_monthly_snapshots for monthly interval and https://data.nas.nasa.gov/ecco/data.php?dir=/eccodata/llc_90/ECCOv4/Release4/nctiles_daily_snapshots for daily interval.

[ifenty]

@owang01
Fields that need to be added:

volume budget

• sIceLoad snapshots (to calculate \partial ETAN+sea ice + snow volume / \partial t$

momentum budget (pending confirmation from Mazloff)

• UVEL, VVEL, WVEL snapshots (to calculate $\partial momentum / \partial t$)
• UVELMASS, VVELMASS snapshots [would these be useful too since they are the are scaled by s*?]
• Um_Diss, Vm_Diss, (momentum tendency from Dissipation)
• Um_Advec, Vm_Advec, (momentum tendency from Advection)
• Um_Cori , Vm_Cori, (momentum tendency from Coriolis)
• Um_Ext, Vm_Ext, (external forcing)
• TOTUTEND, TOTVTEND (these are actual tendencies)
• VISrI_Um, VISrI_Vm (vertical viscous flux of momentum)

[ifenty]

We also need the LAST snapshots of all the snapshot fields (20XX-12-31)

[ifenty]

2019-01-24

issue 1:
latitude and longitude and depth need to have the 'axis' string attributes
axis = 'X'
axis = 'Y'
axis = 'Z'

issue 2
can get suppress the variable of i,j,k?

issue 3
can the order of 'coordinates' be reconciled with the order of the actual array

issue 4
timestep should have better description (number of hours)

issue 5
time_bnds needs to say days since 1992-01-01

issue 6
why is there a global attribute of "coordinates" that is only "time_bnds"

** issue 7 **
make 'date created' the same format (iso) as the other times"

** issue 7b**

noticed that the iso format for the times are not exactly identical everywhere.

** issue 8 **
need entire heirarchy of GCMD, separated by a '>' between the heiracy elements and a ',' between the different GCMD keywords.

** issue 9 **
add 'comment' field to global attributes that includes

** issue 10 **
in the 'title field' include the "dataset name"
e.g.,
ECCO v4 Release 3 Potential Temperature and Salinity

issue 11
consider using the global attribute 'history' field : could include data
consider using the global attribute 'source' field : "source should name the model and version"

issue 12
data best practices

https://podaac.jpl.nasa.gov/PO.DAAC_DataManagementPractices

"references" | string | Published or web-based references that describe the data or methods used to produce it. Recommend URIs (such as a URL or DOI) for papers or other references. This attribute is defined in the CF conventions.

issue 13
use the attribute to use "coverage_content_type" on all variables and coordinates

       # ISO 19115-1 codes
        valid_ctypes = {
            'image',
            'thematicClassification',
            'physicalMeasurement',
            'auxiliaryInformation',
            'qualityInformation',
            'referenceInformation',
            'modelResult',
            'coordinate'

for spatial measures we could use:
auxiliaryInformation
referenceInformation

for the majority of fields it'll be 'modelResult' or 'coordinate'

issue 14
NASA best practices specifies that for satellite datasets there should not be a _FillVlalue for time variable

issue 15
units should have this format m2 s-2

issue 16
no need for nx, ny, or nz

issue 17
"processing_level" must have an underscore. ncdump shows a space, and panoply puts an underscore.

issue 18
compare file sizes using 0 as fill values vs. max float.

issue 19
compression (level 1 vs level 9)
https://www.unidata.ucar.edu/software/netcdf/workshops/2011/utilities/Nccopy.html

https://www.unidata.ucar.edu/blogs/developer/entry/netcdf_compression

issue 20
netcdf file naming conventions

issue 21
dataset naming convention

issue 22
compliance checker

https://podaac-tools.jpl.nasa.gov/mcc/

issue 23
can xarray use compression when generating netcdf?

http://xarray.pydata.org/en/stable/generated/xarray.Dataset.to_netcdf.html

** issue 24**
grid cell area

http://mathforum.org/library/drmath/view/63767.html
t is a consequence of a theorem of Archimedes (c. 287-212 BCE) that for a spherical model of the earth, the area of a cell spanning longitudes l0 to l1 (l1 > l0) and latitudes f0 to f1 (f1 > f0) equals

(sin(f1) - sin(f0)) * (l1 - l0) * R^2

where
    l0 and l1 are expressed in radians (not degrees or whatever).
    l1 - l0 is calculated modulo 2*pi (e.g., -179 - 181 = 2 degrees, not -362 degrees).
    R is the authalic Earth radius, almost exactly 6371 km.

The area of a lat-long rectangle is proportional to the difference in 
the longitudes. The area I just calculated is the area between 
longitude lines differing by 360 degrees. Therefore the area we seek 
is

  A = 2*pi*R^2 |sin(lat1)-sin(lat2)| |lon1-lon2|/360
    = (pi/180)R^2 |sin(lat1)-sin(lat2)| |lon1-lon2|