Rain seem off (auto-calibration system not yet deployed)

sky
false-rain
drizzle

#151

The same happened to me the other day with a magpie, also same result -Push App sent notification but no rain recorded in WF app however, interestingly, weather display did register the event.(including the eclipsing of the UV/light sensor.):sunglasses:


#152

True, they are expensive. I was thinking about the WeatherFlow engineers/scientists that are developing the calibration algorithm. Instead of purchasing one they could install systems here; www.arm.gov. At the SGP research site for inter-comparison. They have all manner of precipitation measurements - including the Parsivel.


#153

(Used Car Salesman Mode)

If I could put you in one of those 24 Ghz devices for under $500, would you drive it off the lot today?

(/Used Car Salesman Mode)

(FOB China, of course.)

I was looking at buying one a few months ago, but the published accuracy specs of the ones that I was looking at (including big $ players like Lufft IIRC) were not even on par with a $50 tipping bucket for 50x more…


#154

Had .25 inches of rain overnight. It was a light rain over a long duration but the sky reported no rain at all. I tapped the unit to make sure it was still register in and it reported rainfall.


#155

OK, so first the obvious problem. As stated, serious overestimation of rain.

Just to illustrate take a look at August 14th on my Rain graph:

Then look at August 14th on the local weather station:

http://www.bom.gov.au/climate/dwo/201808/html/IDCJDW7021.201808.shtml

The weather station measured no rain and the Sky, well as much as 2m (yes meters!) of rain in an hour. Hmmmm.

Go figure. Now I know that it’s a haptic sensor, and I know that I have a scheduled check for and fix of any loose bits and sources of vibration. Got that. Even went up recently and did half that and decided it needed a fix. For context here is the station:

https://community.weatherflow.com/t/photos-of-sky-and-installation/132/193

Basically there’s a TV aerial (A), and I slid an aluminum post over the top of it taller than the aerial by about 300mm (B). Snuggly inside that is another aluminum post, that is about 600m long ©, that sits snuggly on top of the aerial and finally there’s a 3m length (D) snuggly around that and atop that is the Sky.

To be clear B is a little loose on A, so at base has two orthogonally situated clap screws through it holding it tight and no wobble. At the top because the aerial is attached to the top of the aerial pole (A) with a U-bolt, that’s now around B and A. B has two vertical slots cut into it so it compresses tight and snug on A.

That junction between B and A at the top of A, has a wobble in it I found. I have to tighten the U bolt and/or dismount and cut another slot so that aluminum post (B) can close tightly around the aerial post (A).

The whole rig is tall and aluminum so sways in the wind (has no guy wires) but it is aluminum tubing form an old aerial structure and I am indeed still waiting for the strongest gusts of the year to see if it survives well without bending. If I trust Sky the peak gusts since installation have been around 80 kph (on Aug 15, surprise surprise around the day of that extreme rain measure above though the max win gust agrees well with local weather station that recorded a peak of 85 kph that day, certainly within microclimate tolerance).

All that aside, I know that on my list is to remove that wobble from the A-B connection at top of A.

BUT, my real question is this: Clearly if there’s a wobble or vibration in that joint that is travelling back up the post to the sky and tricking the haptic sensor into thinking raindrops be falling I’d be interested in the salient question of … wait for it … calibration. I’m curious what kind of signal is counted as a drop and how (actually as an engineer with a background in signal processing I’d be curious how it worked full stop, imagining a running time series correlation against a typical raindrop signal, though the different sizes of drop and angles would provide a family of candidate signatures methinks and my experience and recollection runs a bit dry). But I am curious what the haptic tract looks like and would love to see a graph of that, annotated with detected drops as a kind of insight into Sky’s innards.

So my question is in a sense, if nay such thing is possible in the field, or if you (devs) would agree that some kind of drill down into this data might have appeal and use to a sector of your market?

Not least because often the human eye remains a good deal better at interpreting such signals and differentiating signal from noise, and it would be nice to see clear noise. In a case like this as a before/after look at the sensor readings, before and after I fix this observed vibration between the poles.

Because I remain concerned that once that’s fixed, that there is still an issue present. We shall see.


#156

Your Sky battery says it needs replacing. Could that be the issue?


#157

Not likely, it was fine until a few days ago. Funny how the battery charge nosedived in two days … rain overestimation has been an issue the whole while I’ve only now found time to sit down and describe it well. But I do have go and tighten up that pole a little and see if it improves. That does leave the question if there’s away, or might be in future, to see the actual haptic sensor output before it’s interpreted to produce rainfall estimates. For reasons I mentioned in the OP that’s very interesting.


#158

My WeatherFlow is overestimating rain as well. I’m going to try to isolate it from the fence it is mounted to… I have 10’ section of 1.25" pole mounted to a iron (more like steel) fence.

It is off by at least 3x on heavy rainfall events.


#159

mine is just…incorrect…

0.23 inches here in last two days - VP2 and CoCoRAHS manual gauge agree perfectly.

I can’t figure out the blasted WF rain gui in the browser but I ‘think’ it thinks I got 0.18 inches those days. Maybe.

weewx running the UDP listener thinks we got 0.15 inches. Grafana measuring and summing up the distinct measurements also calculates 0.15 inches over two days.

Just for the record (so I don’t forget) - the math I did was to add up all the non-zero accumulated rain measurements and convert to inches. Got the same result in Excel and Grafana (whew)…

58%20AM


#161

As a reminder, the WF auto-calibration system for rain accumulation has not yet been deployed.


#162

Do we have any even speculative target date to expect this ?


#163

It’s in development and testing and we have not been told the progress.


#164

Real Soon Now. Probably not in time for Florence, unfortunately, but hopefully before Joyce, Kirk or Leslie get here!


#165

Well, this is interesting (at least to me). Over the last 24 hours the Weather Flow has been UNDERreporting our rain, the complete opposite of last week.

Rainwise tipping bucket 1 - 1.60"
Rainwise tipping bucket 2 - 1.54"
Cocorahs at home - 1.64"
Cocrahs at school (6 miles away) - 1.55"

Weatherflow - 1.06"


#166

We have 2 WF Stations at different locations - both are over-reporting (at least for the past few weeks).
I realize that work is being done to improve this but thought I would chime in.
The 2 Station IDs are 4917 and 4924.
I am willing to help out or “Beta” test if needed.


#167

And what about verry light rain. Like Drizzle.

We had it the whole night… and a total precipitation of 4 mm.
But the Sky reported nothing.

Is the calibration system also for the verry light rain?


#168

The current calibration function tends to under-report light rain and over-report heavier rain. That’s one of the things the new calibration algorithm addresses.

SKY does have a lower limit so extremely light rain (aka “misting” or “fogging”) may not be detected, but that type of precipitation does not normally account for a significant amount of water. However, 4mm overnight is a not an insignificant amount of rain. A properly-functioning SKY is very sensitive and should report any actual drops that hit it - anything you can feel on the palm of your hand and some that you can’t. The calibration system will not affect the lack of a signal and if that continues, we may need to send you a new unit.


#169

It was not misting or foggy… Pure drizzle… But the Sky didn’t sense it.
As I look at the surrounding stations…they all have precipitation off about 4 mm.
There were even puddles this morning.

I will keep an eye on it. With heavier rain the Sky performs verry well.

Maybe it was just to light for the sensor. But if I look at the smart weather map, surrounding Sky also didn’t measure any rain.

Edit: did a quick check. When I hit the pole with something it immediately responds. So it is still working… Only the drizzle that it is not reacting to.


#170

Thanks for the follow-up. We’re rolling out a new firmware build over the next couple days. It includes a new calibration routine that paves the way for better rain data. Let’s see how the rain data from your SKY looks over the next week or so (yours and others), and if you’re still not getting a signal when there is clearly rain happening, we can dig deeper and send you a new unit out if it looks like yours is faulty.

In our testing, SKY actually responds quite well to hail. That is, it’s usually easy to differentiate between hail and rain in the data. For now this is still being reported a “lots of rain” but once we dial in the rain auto-calibration system, we will turn our attention to how best to detect and report hail.


#171

Thank you @dsj for your great support. :ok_hand:
Verry curious about the new firmware. I will keep an eye on my SKY how it performs.

Where not getting a lot of rain the next comming days.

About the hail,
The SKY indeed noticed VERRY HEAVY in the rain mixed with hail last week. So that’s oké.
Would be great if it could sense the difference between hail and rain.