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<DIV>Hi Sam,</DIV>
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<DIV>Two things.... </DIV>
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<DIV>Its documented that tipping buckets can have trouble keeping up with moderate or greater rainfall with excess precip slopping over the cups.</DIV>
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<DIV>We are in the process of publishing siting guidelines for CWOP members. In the siting guide, we recommend that members site their precip gauge at 2.0 feet (0.6 meters) above ground level in an effort to minimize the very real problem of rainfall undercatchment caused by winds blowing up over the leading edge of the rain gauge. Wind speed increases rapidly with even small increases in elevation so it is very possible the cause of the precip differences. The the rule to follow is the lower you site your rain gauge, the better (the opposite of this concept is siting of rain gauges on rooftops is a bad idea). The qualifier if the lower is better rule is to make sure 1) rain falling outside the rain gauge doesn't splash into the gauge, and 2) adjacent trees, walls, and fences don't "shadow" the rain for your rain gauge. At 2 feet, you also need to keep the grass and creeping vines from overgrowing the gauge.</DIV>
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<DIV>We will have the CWOP Siting Guide out for the review in a couple weeks and hope ya'll will give it a good look.</DIV>
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<DIV>Regards,</DIV>
<DIV> </DIV>
<DIV>Dave</DIV>
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<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">-------------- Original message -------------- <BR><BR>> Altho this might not be strictly within the context of data quality, <BR>> per-se, I wanted someone else' thoughts on this. <BR>> <BR>> Have noticed a decent amount of difference in the quantity of <BR>> measured rain in my 8" NWS gauge vs. my Davis rain gauge, and the old <BR>> 4" gauge. With today's rain event the 8" gauge contained 0.75", the <BR>> Davis gauge recorded 0.62" and the 4" gauge had 0.65" in it. Are the <BR>> 8" gauges really that much more accurate than a 4" or a tipping bucket <BR>> that is properly calibrated? The 8" is located about 2' lower, but <BR>> within 5' of the Davis gauge, and the 4" gauge is located out in the <BR>> clear but 6' off the ground on the top of a privacy fence. Don't think <BR>> there would be any turbulence from the house affecting the 8" or the <BR>> Davis. Do I need to do some calibration on the tipping bucket? This is <BR>> the 2nd or 3rd time I've noticed a relatively significant difference <BR>> between the 8" NWS gauge and the Davis tipping bucket gauge. <BR>> <BR>> Comments? <BR>> <BR>> -- <BR>> Sam <BR>> <BR>> _______________________________________________ <BR>> wxqc mailing list <BR>> wxqc@lists.gladstonefamily.net <BR>> http://pond1.gladstonefamily.net:8080/mailman/listinfo/wxqc </BLOCKQUOTE></body></html>