Thanks for that. The AMO site that I used isn't as long a period as you linked, but it's very easy to see that it isn't as high as it was toward the end of '22. NOAA OOPC

What prompted me to ask was your mention of a 3.87 sigma event happening. My use of the Gaussian tables in my ex-profession (retired) left me with another implication: either it's not Gaussian or otherwise not an accurate distribution. 1 in 18,650 events are not exactly common. The fact that we have one is potentially a "head's up" that our understanding is wrong. In the electronics industry, the goal was "6 sigma quality"; anything that could be anticipated or designed for within 6 sigma of the design value was supposed to produce an acceptable product. Generally, a 4 sigma situation was a sign that the models weren't right.

The possibility that it's just showing the effects of lower SO2 emissions just raises the question of how much that could be and whether or not the magnitude is reasonable.

Sorry, just trying to learn and understand as much as possible.