In reply to above and pm's, I thought doing this on the forum would open it up;
The first thing that you need to do is establish the cross sectional area of the gauges collector. Please see "NEMS" document in your Fine Offset Thread.
http://www.meteocercal.info/forum/Thread...264?page=3
On Page 44 (of document, p58 of pdf) there is a table which states that calibration is done using 653mm of water.
This means that the diam of the TB3 is 203.89mm (remember this is sharp edge to sharp edge: or the "watershed" of the gauge, one of the many factors that contributes to the "vagueness" of FO gauges is the lack of a sharp edge.)
653 ml
65300 / 2 = 32650
32650/Pi= 10392
Square root of 10392 = 101.945mm radius x 2 = 203.89mm diameter.
Check your gauge diam accurately using a vernier. It is probably the same as the TB3, but you need to check. You cannot do any other calibration until the cross sectional collector area of your collector is known. All rain gauge calibration, whatever type it is, must start with this. If the diam is different to this you will need to do the arithmetic on the FO post:
Assuming it is the same 203.89mm then the rest of the calibration should be done using the NEMS table on page 44. (99 to 109 tips per 653ml etc.etc.). It also gives acceptable validation ranges. If your gauge is not 203.89mm diam, then one will need to draw up a similar table after establishing a new cross sectional area.
I suspect that your gauge has been very well calibrated given the seals on all the adjusters. So I would be very loathe to start changing anything until you are absolutely sure of the basic starting point sums of cross sectional area as outlined above.
If the TX config is changed to 0.200 it will take 326.5ml of water to register 10mm on the readout after 50 tips of the bucket. (not the 314ml mentioned earlier which assumes a 200mm diam.)
I attach a pdf from the Australian BOM with further ideas and numbers.
The first thing that you need to do is establish the cross sectional area of the gauges collector. Please see "NEMS" document in your Fine Offset Thread.
http://www.meteocercal.info/forum/Thread...264?page=3
On Page 44 (of document, p58 of pdf) there is a table which states that calibration is done using 653mm of water.
This means that the diam of the TB3 is 203.89mm (remember this is sharp edge to sharp edge: or the "watershed" of the gauge, one of the many factors that contributes to the "vagueness" of FO gauges is the lack of a sharp edge.)
653 ml
65300 / 2 = 32650
32650/Pi= 10392
Square root of 10392 = 101.945mm radius x 2 = 203.89mm diameter.
Check your gauge diam accurately using a vernier. It is probably the same as the TB3, but you need to check. You cannot do any other calibration until the cross sectional collector area of your collector is known. All rain gauge calibration, whatever type it is, must start with this. If the diam is different to this you will need to do the arithmetic on the FO post:
Assuming it is the same 203.89mm then the rest of the calibration should be done using the NEMS table on page 44. (99 to 109 tips per 653ml etc.etc.). It also gives acceptable validation ranges. If your gauge is not 203.89mm diam, then one will need to draw up a similar table after establishing a new cross sectional area.
I suspect that your gauge has been very well calibrated given the seals on all the adjusters. So I would be very loathe to start changing anything until you are absolutely sure of the basic starting point sums of cross sectional area as outlined above.
If the TX config is changed to 0.200 it will take 326.5ml of water to register 10mm on the readout after 50 tips of the bucket. (not the 314ml mentioned earlier which assumes a 200mm diam.)
I attach a pdf from the Australian BOM with further ideas and numbers.
