"Roy Avis" wrote :

I have a standard 5 " gauge a few metres from my Vantage Pro 2, and up to
0900 today I have recorded 95.3mm in the 5" and 93.8 via the VP2 tipping
bucket.
This 1.5 mm diffence has been about the same since the rains of mid
January, so it would seem that some tips may be lost during high rain
rates.
However, this difference is only about 1.5%. Your 15% difference suggest
a more fundamental problem!

Roy, most of the difference comes from the different exposure of
the rain-gauges. If you are achieving only a 1.5% shortfall in an
elevated gauge you are doing exceptionally well. I'd be interested
to see if you maintain that figure. Most users who have made a
systematic check over a long period report a loss between 5
and 15%, the variation indicating differences in the effects of
turbulent air flow around the elevated AWS gauge.

Philip