"N_Cook" wrote in message news
Anyone know which version is corrct?
I suspect Wipneus is using a different data feed than the Charctic one,
area rather than extent perhaps, JAXA ?

TBH I'm not too bothered about this slight day-to-discrepancies, irritating
though they may be, because there are several possible causes. It could be a
slightly different algorithm in use, which is fine in one sense - one
wouldn't expect different sources to give _precisely_ the same value on any
given day and indeed there may be some days when the trend ticks up from one
source and down on another. But as long as the overall trend averaged over a
few days is comparable on multiple sources then I'd suggest that's actually
powerful evidence supporting the conclusion that we're watching major
milestone events in global sea ice.

But what is tricky for us amateur observers to assess is exactly how the
different sources are processing the data. For instance, I'm never quite
sure what the date on the charts actually means - is that the date of the
data or the date on which the chart was prepared (ie maybe using yesterday's
data). And sometimes the charts don't get updated every day - maybe if the
charts are coming from academic institutions then perhaps they may not
(always?) get updated at weekends? So, as I write, the latest data on the
NSIDC Charctic chart is 20th Jan and perhaps in 2-3 hours time this will
update to 21st Jan. But the latest Wipneus charts that I can see are still
dated the 19th.

And then there's the issue of whether the data are single-day or 3- or 5-day
means from different sources.

Wipneus does specifically mention that his/her data is sourced from NSIDC,
though I don't know whether that automatically means that it's the same as
Charctic or not.

Finally, I suspect that any serious questions would be welcome on the arctic
sea ice forum eg on the thread at:

https://forum.arctic-sea-ice.net/ind...c,1837.50.html

You never know, you might get an answer direct from Wipneus?