For several years I've been running my VP2 station with the understanding that the rain gauge "may" record low during times of heavy rain. A good friend about four miles away from me has many times reported to me more rain than what my Davis unit has recorded. He has a basic 1" diameter gauge. I figured there was the distance between our locations, his location in regards to trees, buildings, etc., (mine ISS location is fantastic...right?
), the "if it rains hard it will record low" idiom, etc., that was causing sometimes an inch or more difference in readings. Naturally, if we were talking about scattered showers the differences are understandable, but when talking about a set-in, widespread rain system it seems that 4 miles wouldn't make too big of a difference...the differences in our gauges did make me wonder.
Sub-tropical storm Alberto passed through here last night. For the same time period of prior to Alberto's arrival until this morning the readings were:
Davis VP2 = 2.59"
CoCoRaHS = 3.60"
The two measuring instruments are roughly 60' apart from each other. The CoCoRaHS gauge has a large pine tree probably 30' to the NW of it. I know, to do a better comparison the two gauges should be basically mounted side-by-side. But...a whole inch of difference? Seems like a bit much to me. I've never looked into it, but can the VP2's rain gauge be "calibrated"?
Feedback definitely welcome!!!
Ed