The different plots are for:
(ITCZ = 7 S)
Sagar Kanya, 1996 (5 S)
Ron Brown Leg 1 (2 S)
Ron Brown Leg 2a (Leg 2 going North ) (4 S-- just a guess here)
Ron Brown Leg 2b (Leg 2 from far north to farthest south) (11.3 S)
Ron Brown Leg 2c (Leg 2 return to Male') (ITCZ shifted to 9 S)
In each case, I put the "ITCZ" where I thought the fully Southern Air began. So the zero latitude on this plot is really the southern *edge* of the ITCZ.
The 3-tiered structure is interesting! Obviously the south is pretty much always the same, but then it looks like the second tier is NH background, the third is what we get if we're getting something off the continent, but it was a ways away, and the wild stuff is what we get when it comes to us on the A-train. I guess that makes it 3 tiers plus one special case.