geolocation variables reset?

[nmt28]

When using ICEPYX, I notice that in the geolocation of my subset file, that the ph_index_beg appears to begin at 0. Does ICEPYX reset this during the subsetting?

#edit I have checked a few files I have from different locations that were downloaded with ICEPYX and it appears consistent behavior.

#edit 2 Thinking on this more, this makes sense and it is probably an NSIDC API subsetting question than a specific ICEPYX question, but if someone wants to confirm/deny this go ahead, otherwise it can likely be closed out

[JessicaS11]

Hello @nmt28! Thanks for sharing your question and the updates. As you noted, if this is happening at the file access level (rather than during file read-in):

it is probably an NSIDC API subsetting question than a specific ICEPYX question.

To get you subset data, icepyx itself does not actually do any subsetting, it just passes the correct subsetting keywords to the NSIDC API. @mikala-nsidc, can you confirm that the ph_index_beg is reset to 0 by EGI during subsetting?

[mikala-nsidc]

I'll check!

[mikala-nsidc]

@nmt28 Can you tell me if you are using any other customization options, like file reformatting?

[mikala-nsidc]

Also, which data set are you downloading?

nvm - I see it in ATL03.

[nmt28]

Thanks both, I played around with the data some more and found that ph_index_beg is indeed reset to 0 when subset - which actually makes sense if you think about it hard enough. As I first thought, this is indeed an NSIDC issue, but I wanted to rule icepyx out as a source of my initial confusion

[mikala-nsidc]

Hi Nathan! I'm actually worried about this one, because the subsetter shouldn't change any data. I did some testing the previous week and then was going to touch base with you, then this week I was out sick. I've entered a ticket for this to be looked at further by our developers. I'm not seeing a resetting to "0" when I subset, but I'm seeing a truncation of certain numbers. Any chance you could share some screenshots of what you are seeing? Maybe a comparison of the same location for both an original file and a subsetted file, assuming that's how you tested?

[nmt28]

@mikala-nsidc sorry for the delay on this. I'll reopen this and will try and get some more examples/info to you. To start, here is a quick screenshot of a subset file that shows that ph_index_beg starts at the "beginning". This makes sense to me as this is effectively a photon "count" within the file, so begins at 1, irrespective of where the track starts