@J42ds said in Colour shading of SO2:

Thanks. I am in Australia (Melbourne). I have never seen so much red on the map. A couple of days ago, the reading at my location was around 1 and the forecast was for a wind change to an Easterly, which would blow the SO2 towards me.

At the moment it’s showing a level of 18 mg/m2, which is way above the forecasted level. (I do understand that this is per m2 and not per m3, so a value for the whole column).

I’m trying to understand where all the extra SO2 has come from. Volcanic activity??

That's a really insightful observation, and you're right to dig deeper into this — seeing such a spike in SO₂ levels, especially jumping from 1 to 18 mg/m², is definitely unusual and concerning. The sudden rise could indeed be linked to volcanic activity, particularly from eruptions in the region (like Indonesia or Tonga), where prevailing winds can transport SO₂ over long distances, even reaching southern Australia. It's also possible that atmospheric conditions, like a temperature inversion or lack of dispersion, could be concentrating it more than forecasted. Monitoring wind patterns and satellite data for volcanic plumes can help explain these anomalies. Appreciate you sharing — it’s like piecing together a complex recipe from the atmosphere’s menu!