"Richard Griffith" wrote in message
...
I'm trying to calculate the monthly rainfall duration (hours) using data
from my
Tipping Bucket Gauge - this is connected to a data logger (Casella
Rainfall Logging System) and the Gauge tips every 0.2mm
Using the gauge software I can look at minute data. Now this is where I'm
not quite sure of things
For example a month gives a total figure of 585 minutes (585 / 60 =
9.7hrs)
Is this method of calculation correct - its seems very low for the entire
month ?
How should rainfall duration be calculated using a TBR ?

As others have explained, it can't really be done. Last year I did
a fairly detailed comparison at Hampstead of the AWS's tipping
bucket gauge and the Dines Tilting Syphon Rain-Gauge (if
you're not familiar with it, this is a mechanical device which was
standard until recently which provides a continuous record of
rainfall duration, amount, and intensity), and I couldn't devise
any simple rule which would allow the tipping-bucket to emulate
the Dines TSR in respect of duration.

I did come up with one rule of thumb, though, which you may find
useful. Defining a wet hour (Hw) as one with rain recorded by
the tipping bucket, monthly rainfall duration approximately
equalled 0.75*Hw. The figure varied somewhat between very
dry months and very wet months, though during the short
period of my comparison this variation didn't appear to be
systematic enough to build into the equation.

I dare say the figure (that is, the 0.75 above) would vary slightly
according to what part of the country you're in ... i.e. what sort
of rainfall regime you have.

Hope this helps a little
Philip Eden