Chlorophyll a is considered as primary pigment , while chlorophyll b as accessory pigment supplying energy to chlorophyll a.Thetefore , both the pigments are supposed to be positively correlated , since both the pigments compliment each other.But r=1.00 , I doubt such a perfect correlation...
it is no doubt that both of them are positively correlated. However, it is impossible to keep r=1 all the time, especially when plants are under biotic or abiotic stress
The chlorophyll a/b ratio can change according to environmental condition.
More precisely, it is indicative of the antennae/photosystems ratio, because chl a is present in both antennae and photosystems, while chl b is present only in antennae (light harvesting complex II and I).