Since the values are different for flight AF447, it is likely that there was a significant and rapid decrease of the effects
For the duration, as for the intensity, I invite you to look at the traces in the BEA Final report. Furthermore, it is not obvious on what information that statement is based. Maybe it would have been better to write: "... it is
possible that there was a
significant and
rapid decrease of the effects, which
could explain ...".