What does interannual mean?

Sentence:


In summary, our three scenarios include: "all process error," where INTERANNUAL variation in the estimates of abundance is determined by process error rather than sampling error...





They are talking about research methods of whale populations.

What does interannual mean?
Interannual variations are anomalies of the annual or seasonal cycles which can reach extremes some years or may disappear.


Any phenomena which changes from year to year is said to have interannual variability. Such statements as "its hotter than usual this year", or "we got a lot more rain than usual this year" are both examples of interannual variability. Investigation of interannual variability is nessecary to distinguish long term trends from random fluctuations