posted on Mar, 5 2011 @ 12:26 PM
reply to post by Fritzthecat
This is a post by puterman on the yellowstone thread that may relate to what you are seeing.
"By the way, there has been some discussion of the 'scale' on the IRIS webicorder plots. I had some information back from my contact at the IRIS
DMC. I have asked for a bit of further clarification. Note this does NOT apply to the plots from IsThisThingOn / UUSS as far as I am aware.
The webicorder plots use a "heuristic" RMS algorithm to calculate the vertical scaling.
As the data for a given day changes, the RMS value for the day will change and hence the vertical scale will change.
Hope that answers your question.
Just curious, what are you using the plots for? Do you need more information?
You can see a perfect example of where this has had a major effect today on WHAR.AG. The big 4.7 mashed the trace and has meant that all display
following that has been considerably reduced in sensitivity.