Your idea makes sense to me, i.e., there's on need for a string as qualifier _if_ we're talking specifically about Astronomical Season or specifically about Meteorological Season; otherwise a string might be necessary to clarify what kind of season is referred to. The paragraph you quote is talking about what might be called "informal seasons": neither astronomical nor meteorological. I see a few other issues as well.
First, I haven't looked at previous discussion, but according to the spec, qualified season is defined by:
season = year "-" seasonNumber
seasonQualified = season "^" seasonQualifier
So, following your proposal, one could say "2015-21^N" (2015, Northern hemisphere Spring) or "2000-23^S" (2000, Southern hemisphere Autumn).
Also, the season might be known but the hemisphere unknown, especially but certainly not exclusively for events taking place near the equator. Therefore it should be legal to use "u" as well as "S" or "N", e.g., Spring^u" or "Autumn^u". Or perhaps the full word "unknown" would be better than "u".
Finally, the earth's rotation is gradually slowing, and the mean year length in the Gregorian calendar, 365.2425 days, isn't even exactly what it should be now. If the year is far in the future or the past, the seasons might well precess relative to the date. This is not likely to a problem for EDTF's main applications, but if people are going to use it with 7-digit years, well...
On Apr 3, 2015, at 6:27 PM, Nathan Harrenstein <[log in to unmask]>
> I read through the previous discussion on season qualifiers, but I am not sure why there is a need for a string of text.
> The only important information necessary to qualify the season is a hemisphere. The seasons in the northern hemisphere are the opposite of those in the southern hemisphere. The winter and summer solstices are swapped, as are the vernal and autumnal equinoxes.
> The exceptions are meteorological seasons (which are seasons created by meteorologists) and, quoting from the first paragraph in the first link below:
> The dates on when these seasons begin and end can differ depending on who you ask. People in Australia and New Zealand for example, consider September 1 as the beginning of spring. The Irish on the other hand believe that spring begins on February 1, when they celebrate St Brigid's Day.
> However, if the feature were called "Astronomical Season" instead of "Season" then as far as I know, these exceptions wouldn't be an issue.
> In which case, there would be two possible options: northern or sourthern hemisphere. The notation could be "Spring^S" or "Autumn^N".
Woodrow Wilson Indiana Teaching Fellow
Adjunct Associate Professor of Informatics
Visiting Scientist, Research Technologies
Indiana University Bloomington