The scientific mind in me desires relative data before supporting opinions.
From a relative standpoint I would be interested in variations by yearly decades not by days. I expect large amounts of daily hash in the data but some trending up and down as well.
We can then postulate all we want on the reason for the trending variations.
From a relative standpoint, can we see variations driven by volcanic eruptions (pretty common stuff). Major wars with oil fires? deforestation by burning?
I suspect that air travel emissions are minor compared to the above.