BOE stands for "Blue Ocean Event", and the inclusion of the word "Event" indicates something that can neither be fractional nor partial nor continuous with previous or later states, nor can it really be defined as when some specific measure drops below some arbitrary line.
A proper use of the term BOE would indicated the first time all ice disappears. It cannot really be used to describe the first time ice goes under 1Mkm2 simply because the day that happens will be no different from the day before or the day after. Going under 1Mkm2 is an arbitrary point on a continuum, not an event in real-world terms.
Same goes for this strange use of the term "partial" or "fractional" BOE. There is no such thing as a partial event.
I'm not sure about the history of BOE as a concept, but I remember a few years back when a lot of people become excited about a hypothetical future BOE with several of them claiming that following BOE, ice would not regenerate and the Arctic would flip into a new regime, a tipping point of epic proportion. This line of argument is obviously using BOE to mean "when all ice disappears".
Further to the earlier discussions on BOE were claims that the world as we know it would end shortly afterwards - not only the Arctic but the entire planet would have reached a catastrophic tipping point. Again this line of discussion does not allow for a definition of BOE as meaning "going under 1Mkm2".
I remember reading for the first time some years ago the suggestion that BOE be re-defined as "virtually ice free", and to use the apparently widespread definition of under 1Mkm2 as the arbitry limit. I didn't think much of it at the time.
Buit this confusion of terms is becoming increasingly unfortunate in my mind. People are really talking about VIF (virtually ice free) which is not an event. Thus using terms such as "partial VIF" is reasonable, while "partial BOE" is nonsense. This confusion of BOE with VIF also makes impossible all speculation and discussion of tipping points or sudden and epic systemic changes following BOE - which I don't really believe in, but other people do, and it would be silly for them to try and come up with new terms because some lazy scientists have stolen BOE - are we to start talking about TIFE (totally ice free event) instead?
BOE is an event, something that happens clearly and is easily definable and discernible, and defendable as well. Nobody is going to claim any major changes to the Arctic just because at some hypothetical point in the future, ice extent drops to the 990.000km2s for a few days. That would be laughable, and totally negate the whole idea behind the term BOE.
So i would suggest to stop using BOE as a tag for "virtually ice free". and start using VIF instead. And that the rest of us start to think about how to actually discern when this Event takes place, I personally like the idea of FMI 80N lift-off being the unmistakable sign of a BOE.
<Don't make it personal. O>