[ecco-support] missing values in ECCO V4r4 monthly interpolated climatology

[Ervik, Haakon L.]

Hello,

I am a graduate student at Caltech working on ocean temperature estimation and I have been happily using ECCO data as a reference for many calculations in my research.

A few days ago, I downloaded the monthly interpolated climatology from the ECCO Drive (e.g. https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/interp_monthly/THETA).
Compared to previous times I’ve downloaded ECCO datasets (e.g. V4r4) it appears that the provided netcdf files effectively use the value 0.0 as _FillValue, which is confusing all the time THETA can be both positive and negative.

Using https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/interp_monthly/THETA/1992/THETA_1992_01.nc as an example, I found that for lat= - 66.25 (1-based index 589), lon=114.25 (index 48), the resulting profile is negative near the surface, then positive for a bit, then exactly zero for the remainder of the array (I tried loading the dataset in both Python and Julia). Presumably I reached the sea floor once values are exactly 0.0. I think these should be NaN or Missing (or a really large value) instead. This was done correctly when I’ve downloaded ECCO data in the past.

I’m further confused since, interrogating the global attributes of the dataset, it says it follows CF-1.6 conventions, but the only attribute referring to what should happen with missing data as far as I can tell is a global attribute «no_data» which has value «NaNf».

Am I doing something wrong? Or did something change in how «missing data» is specified in the most recent release of ECCO? Should I direct my questions elsewhere?

I appreciate any help.

Best,
Haakon


--


Haakon Ludvig Langeland Ervik [haw-kon]
PhD Student, Environmental Science and Engineering
California Institute of Technology
www.hlle.no | haakon at caltech.edu

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mit.edu/pipermail/ecco-support/attachments/20230925/74af181f/attachment.htm>