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Rain gauge reliability
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Posted by ltecato 9 (My Page) on Sat, Feb 6, 10 at 21:55
| According to a rectangular plastic rain gauge I have hanging on a wooden post, we got at least 5 inches here in Dana Point. But I checked the "official" rain totals from gauges set up by some Orange County government agency, and the highest rainfall total they show is about 3 inches.
I don't believe for a minute that we got 5 inches here, but at the same time I can't figure out how my rain gauge can be lying to me. True, it might not be hung absolutely straight, but it seems to me that if it was a little off plumb it would erroneously indicate less rain, not more.
This rain catcher is situated between two three-story apartment buildings. Is it possible that rain might be concentrated between the two buildings? The gauge doesn't collect any direct roof runoff, but I'm wondering if some of the water may be bouncing off and landing between the two buildings.
I never thought I'd be such a weather nerd, but that's what gardening and advanced age do to a person. I'm even thinking of buying one of those thermometer/hygrometer/barometer gizmos to hang on the wall. |
Follow-Up Postings:
RE: Rain gauge reliability
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If you are on a downslope it could be more. It's possible to bouncing off of other buildings or roof, depending how far away. They should be hung out in the open if possible.
There is someone a mile away from me that continuously gets way more than me...although I'm not buying their numbers. |
RE: Rain gauge reliability
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| It all has to do with where you are located plus wind etc. MANY MANY times I get an inch of rain and a mile away they get 2 Just depends on the storm |
RE: Rain gauge reliability
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As the previous poster said, you should have your rain gauge out in the open away from any buildings. Is the raingauge on the very top of the post or lower down? If lower down maybe water is running off the post or splashing off the post. Also, if you live on a hill you will often get more rain then people in the flat lands. They call that orographic rainfall.
http://encyclopedia.farlex.com/orographic+rainfall
I use a five gallon bucket with straight up and down sides as my rain gauge. You can also get less rain if you are in the rain shadow of some mountain or hill. I know when the direction of the storm puts Fullerton in the rain shadow of Catalina Island we get less rain during that time. |
RE: Rain gauge reliability
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| I do live on a hill, so that may account for some of the anomalies. |
RE: Rain gauge reliability
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| You probably got five inches. My dad lives in La Crescenta, and they got 4.5, we live in Simi and got 1.5. A single hour-long cloudburst can produce quite a bit of rain in a localized spot. I didn't trust our rain gauge, so I measured the water in our 4x7 concrete block pool, and it has 1.5 inches of water in it as well. |
RE: Rain gauge reliability
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| Hosenemesis nice to see another person from Simi. I like to buckets and measure them. My good friend has rain gauge on his Oregon Scientific weather station and I seem to be close to his values and it is line with Simiweather.com. But at times I have seen rain in the area we are in to be twice what Simiweather shows which I think is non the north part of the town. |
RE: Rain gauge reliability
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rasputinj, we should have a Simi Valley garden tour of Gardenweb members this spring. Even though your choice of name gives me the serious creeps...
Renee |
RE: Rain gauge reliability
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- Posted by hoovb z9 Southern CA (My Page) on
Tue, Feb 9, 10 at 0:27
| I just read on a weather site that rain gauges even a few inches apart can vary in measurement by 20%. Rain is not uniform. |
RE: Rain gauge reliability
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| When I was in Vietnam one time I saw it raining on one side of the street but not on the other 100 feet away. When I was in upstate New York I saw a cloud hit a mountain and it was pouring rain in that spot but dry everywhere else. There is a big hill on Euclid in Fullerton and I saw it raining on the top of the hill but dry at the bottom. So you are right, rainfall is not uniform even locally. |
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