Hoping one of you more familiar with hardware and settings can weigh in. Or maybe ecowitt is better suited to explain.
Okay I'll bite. I hope others also weigh in to your questions.
Since there is a calibration factor shown for rain gauges, I can only assume there is a possible need. Has anyone adjusted rain gauge gain and for what purpose ?
Platokidd mentioned his need for adjustment based on his observations in comparing to another trusted rain gauge. There are many others whom have done the same.
The calibration page for my gw1000 shows a gain factor available for the rain gauge. If my gauge is consistently over measuring vs a standard, i would reduce this value below 1.0 to the appropriate level...0.9 or 0.82 based on measured calibration. If under reading, then factor up. My goal would be deliver 25mm equivalent volumeadmin as a controlled test, and system displays 25mm.
Yes, it works exactly as you have stated. But keep in mind that your controlled test is something that is often done with other rain gauges here on this forum. Davis comes to mind. Dumping a set amount of water works for them because their design doesn't lose water and doesn't seem to have tipping rate issues given the collection diameter, at least not to any significant extent. But in this particular situation with the WH40 there are factors that need to be taken into consideration. If you only account for rain accumulation and you manually poor a measured amount of water through the system then if you base your calibration off of only that then you are going to be disappointed in the results. Because you would likely then not be accounting to funnel design and bounce out and deluge rain rates that overcome the rate capacity of the tipping spoon.
Will the rain gauge gain factor do that ? Or is that a Lucy question ?
You can ask Lucy to get an answer from their engineers. But at this point based on your questions so far I don't see that there is anything to ask Lucy. The basic usage of the system is to adjust the rain gauge gain to a factor that you are comfortable with. The factory setting of 1.0 gain is just an average determined by the engineers during the design phase of the product.
While we expect items out of box to be pre calibrated to perfection, every qc job I ever had involved recalibration of sensors, gauges and related periodically.
Yes, correct. But in this case with the rain gauge I think that calibration is mostly a factor of its environment rather than a function of manufacturing tolerances. All spoons are the same size and the springs probably give off the same force within what is measurably relevant. Temperature and friction and use ..etc....could affect the tipper I suppose. And for that reason and other small factors it is nice to see the ability to have a manual calibration setting.
Regarding scientific systems, the pictures I see show arrays of collectors. 6x6 or even 10x10. That tells me there is a lot of variability across adjacent cross sections. If one device was accurate and precise, scientists wouldn't put 36 or 100 in an array. If scientists are planning on variability, they add multiple sensors gauges.
You lost me there. Not sure what this means. But if you are saying that a scientist doesn't go by one measurement.....then yes that is true. Experiments require multiple tests to determine that the results are able to be reproduced and are thus then verifiable. I don't think though that most weather hobbyists are looking to have an array of rain gauges just to account for variability. Sure some have multiple systems just to see how they each perform and for the fun of it too. I think most of use with automatic rain gauges are willing to accept some level of accuracy for the convenience of automation. If not then we would all only have manual rain gauges. Which is why many of us have both manual and automatic. Even manual is not perfect...but we do know that good manual rain gauges are less affected by intrinsic errors compared to automatic rain gauges.
I think the wh40 can be managed and provide a reasonably accurate reading. There are conditions which errors will occur due to design elements., and deluge type rains are what comes to mind.
I'm not so hopeful. The WH65 is not a spectacular rain gauge. Given its price and component build and overall design characteristics it is what it is. The WH65 isn't trying to pass itself as anything spectacular. But the WH40 does have claims to be superior. From various user experience of those that have both a WH65 and WH40 the WH40 is a disappointment in comparison. If the WH40 has design aspects that make it inferior to the WH65 then there is a big problem here, because it is marketed as being superior. It doesn't live up to its claim. On paper it seems as it should just because of the larger diameter...but the other components funnel and tipper fall short of the overall design goals of this product. I just don't think the solution is to find some magic calibration offset. My only hope for the WH40 is that at least it can be made to perform equally to the WH65, and for me that means using the WH65 funnel with the proper calibration offset to account for that collection volume. I know that are those that disagree with this sentiment of needing to replace the WH40 funnel for a smaller diameter. And to those people I say ...have at it. Figure it out. Find out what offset is required to account for bounce out and for tipper overflow. Platokidd has already worked that out with some empirical testing of merely comparing one rain gauge to another. That is awesome! Two different approaches. Neither perfect.....but the WH65 isn't perfect either and I do keep that in mind. My goal is not to make the WH40 acceptable to some great standard...rather my goal is to make the purchase of the WH40 a good purchase as compared to the WH65. Further into the future sure I do expect Fine Offset / Ecowitt to come out with a totally new solution that is better than both the WH40 and the WH65....something that lives up to the WH40 claims of superiority.
