[ncl-talk] month_to_season() how does it work?

[Erik Jan Schaffernicht]

I am not sure how month_to_season() function works for   DJF   (and NDJ 
is probably similar).

Say, I select "DJF"

I take the years like this:
[snip]
iYYYY=  ind(YYYY.ge.1979 .and. YYYY.le.2003)
slp= ifle->slp(iYYYY,:,:)   + ...   (further steps, input from ncep slp 
data.nc, and I flip some dimension to make it fitting to formal 
requirements)
slpSeason=  month_to_season(slp, "DJF")
[snip]

What does the month_to_season() exactly do?

My understanding of 'what belongs to a season' written down looks like 
this, if I group it by DJFseason:

1979-Jan and 1979-Feb
1979-Dec and 1980-Jan and 1980-Feb
...
2002-Dec and 2003-Jan and 2003-Feb
2003-Dec

How does  month_to_season() process this?
It says that DJF takes only  two months?   Does it mean only two for the 
first entry of this list, i.e. 1979-Jan 1979-Feb     but thereafter it 
takes always three, so 1979-Dec + 1980-Jan+1980-Feb, so three months in 
general except for one exception at the beginning?
Or is it always
1979-Jan-Feb
1980-Jan-Feb
1981-Jan-Feb,   so December is skipped completely?  Then the "*D*JF" is 
confusing!?

And what happens to the 'lonely'  2003-Dec? It has no neighbouring 
DJFmonths due to time range selection by years AD.  Is it skipped? Or is 
it: "take this month and define it as a season"?









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