Topic: VP2 tipping spoon raingauge?

[mikeym2m]

One thing I noticed is that the rain gauge must be perfectly level. When I first remounted the ISS it was just slightly out of level tilted toward the back of the cup and the water would run over the back of the cup and it wouldn't tip.

Cheers

MikeyM

[jgentry]

One thing I noticed is that the rain gauge must be perfectly level. When I first remounted the ISS it was just slightly out of level tilted toward the back of the cup and the water would run over the back of the cup and it wouldn't tip.

Cheers

MikeyM

The RainWise is the same way. Since I’ve couldn't achieve perfection, I adjusted the screws to where the gauge could perform like it should.

[drew1021]

One thing I noticed is that the rain gauge must be perfectly level. When I first remounted the ISS it was just slightly out of level tilted toward the back of the cup and the water would run over the back of the cup and it wouldn't tip.

Cheers

MikeyM

The RainWise is the same way. Since I’ve couldn't achieve perfection, I adjusted the screws to where the gauge could perform like it should.

Yeah that ol perfection bug will sometimes make you feel like   

[CW2274]

I wouldn't mess with adjustment just yet. That very slight bias may help during heavier down pour.

Understood, however part of the total was a heavier shower that moved through yesterday.

Yeah, personally I wouldn't get too frisky with re-calibrating anything til you get more of a sample size. That's exactly how I jacked up my RW bucket then had to do it all over again, but obviously your call.

[WheatonRon]

I received my new tipper and got familiar with the exchange process (since Davis doesn’t include any instructions) by installing it in a spare VP2 rain base. Not too difficult but as others have indicated previously, it can be installed in your ISS without taking it down. Having done it both ways, I prefer making the exchange without taking the ISS down.

I use the word “exchange” rather than “upgrade” for this new tipper as I am skeptical that the rainfall accuracy will improve. I speak from experience having replaced the rain base several times and changed the collector cone to the aerocone without seeing any meaningful improvement in accuracy but maybe this time....

[drew1021]

One more update today:

We had a mostly cloudy day with a period of light rain with little if any wind associated with it.
I emptied the Stratus gauge this morning at 0715 and read the gauge around 1900 when the rain had stopped. Results...

Stratus     .21
VP2    .21

It appears that the heavier storms yesterday may have contributed to the slightly higher total obtained then.

[twcmaster]

My tipper is still lagging after heavy rains. It was installed on a brand new aerocone and gauge.

Novalynx NWS 8" Manual - 1.06"
Stratus - 1.06"
Old Davis Tipper w/ Aerocone- 1.11"
New Davis Tipper w/ Aerocone- .90"

Looks like there is a problem with my transmitter. The whole setup is in my living room now and rain is still accumulating (>31" now) The temperature has been negative single digits for the last hour, and is now -90 even though nothing is plugged into the Tepm/Hum slot. I am going to have to get a new transmitter and retry this all over again.

[racer3]

Nobody has posted in awhile. I am wondering how everyone's comparisons are going. Debating if it is worth the switch.

Also was wondering if anybody knows what the NWS uses with their automated ASOS system for precip?

[WheatonRon]

Nobody has posted in awhile. I am wondering how everyone's comparisons are going. Debating if it is worth the switch.

Also was wondering if anybody knows what the NWS uses with their automated ASOS system for precip?

So far not impressed but I really need a good rain. Last night here are my results from my CoCo gauge and my three VP2s:

CoCo gauge, .15
VP2 new tipper, .09
VP2 old tipper, .16
VP2 old tipper, .13

I cleaned all the tippers yesterday of residual rain and dirt so that couldn’t affect results.

[Jester]

Nobody has posted in awhile. I am wondering how everyone's comparisons are going. Debating if it is worth the switch.

Also was wondering if anybody knows what the NWS uses with their automated ASOS system for precip?

I haven't gotten any rain since my initial install/report. Expecting rain today. I have added an aerocone for testing.

[mikeym2m]

So far I've had great performance from the new tipping spoon.
Today:

VP2 with new tipping spoon   .19"
Stratus rain gauge                 .19"

There have been times when there was .01" difference and if I took the cover off of the VP2 spoon was almost full, but not quite enough to tip it so I kind of write off the .01" difference.

As I said before making sure the ISS is perfectly level is very important.

Cheers

 

MikeyM

[openvista]

If I'm not mistaken, one of the reasons to move to the spoon is for people who can't get their setup perfectly level. The spoon operates on weight, not balance. At least that's what I remember from reading preliminary descriptions of the design. I wonder if someone (johnd, rwilhour) can confirm?

[mikeym2m]

In my case the initial installation had the tipping spoon slightly tilted towards the back of the spoon and the water would run out of the back of the spoon and not completely fill so it wouldn't tip. Leveling the ISS solved that problem.

Cheers

 

MikeyM

[galfert]

If I'm not mistaken, one of the reasons to move to the spoon is for people who can't get their setup perfectly level. The spoon operates on weight, not balance. At least that's what I remember from reading preliminary descriptions of the design. I wonder if someone (johnd, rwilhour) can confirm?

I can confirm. I read the long tediously boring patent filing. It mentioned various advantages like it didn't need to be perfectly level. The spoon does not fill 100% when ready to tip to accommodate for slight leveling alignment. And yes the tipping occurs by weight but not of total weight but by weight difference between tips, meaning if debris or some water didn't fully empty (caused by adhesion) it doesn't matter because it re-zeros (tare) after every tip.

[miraculon]

I cleaned up the old tipping bucket to put it away for storage. I was reminded that the old buckets are "chrome" plated.

I have noticed that the new spoon is just black plastic.

Does anyone know why the spoon is not plated? Why the buckets were in the first place? I can imagine that it was a cost-save for Davis to eliminate the plating.

Greg H.

[galfert]

I cleaned up the old tipping bucket to put it away for storage. I was reminded that the old buckets are "chrome" plated.

I have noticed that the new spoon is just black plastic.

Does anyone know why the spoon is not plated? Why the buckets were in the first place? I can imagine that it was a cost-save for Davis to eliminate the plating.

Greg H.

It probably had two purposes. It was an insulating and reflective design to reduce evaporation and it probably was a more slippery surface to ensure more successful drainage when tipping.

[jgentry]

Had light to moderate rainfall yesterday and my Davis station with the spoon recorded the same as the CoCoRaHS gauge.

One of Davis’ big weaknesses just became their strength IMO.

[Jester]

Storm went through Status 0.75 new tipping spoon 0.68 -0.07. Two rain events and I'm not not impressed. I don't think there is a way to calibrate this?

[CW2274]

Also was wondering if anybody knows what the NWS uses with their automated ASOS system for precip?

This oughta cover it...
https://www.weather.gov/media/asos/aum-toc.pdf

[racer3]

Thanks, Going to be some good reading there!

[drew1021]

OK, after our rain event today I have to say so far I'm not impressed by the new tipping spoon assy.
Today's totals:       Stratus      .24
                            VP2     .26

Of the three rain events since I installed the tipping spoon assy two of the events overshot the stratus. I have checked for proper level.

[mikeym2m]

Here's the latest from Thornhurst, PA

VP2       .95  w/ new tipping spoon.
Stratus  .93

Update: Light to moderate rain in the morning and then heavier rain in the evening for about 2 hours. Total was over about 24 hour period.

I'm happy.

MikeyM

[ocala]

Here's the latest from Thornhurst, PA

VP2       .95  w/ new tipping spoon.
Stratus  .93

I'm happy.

MikeyM

What was the duration of that rain event? Was it a quick deluge or a long drawn out event.

[miraculon]

Rain from yesterday as follows:

VP2 (w/spoon): 0.03"
CoCoRaHS: 0.03"
NovaLynx: 0.03"

Greg H.

[dport]

If someone has time and wants to do a manual calibration test that would be much appreciated.  I did this with my VP2 last summer.  I really cooked it though (averaged 4 inches per hour rain rate) because I wanted it to be accurate for the heavy thunderstorms we frequently get in the summer.  Below are my results.  I had an error of just 2.61%:

http://www.wxforum.net/index.php?topic=34706.msg353256#msg353256

The results are in!  At least after two of my tests.  Both tests achieved an average rainfall rate of about 4 inches an hour using 500ml in a water bottle with a pin hole at the bottom.  So, we know that 500ml is supposed to equal 0.92 inches of rain in the VP2.  Here are the actual results

Test 1:  500ml = 0.89 inches
Test 2:  500ml = 0.90 inches

Some water may have been left in the tipper from test 1 to test 2, that could account for the extra hundredth.  Regardless, these numbers are technically within spec according to Davis.  I will also say that I performed this test during the middle of the day with bright sunshine, temp of 87, and dew point of 62.  Some evaporation may have occurred, but probably not enough to make a real different.

Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge. 

*Edit*, just opened unit to see the tipper.  It was about half full at the end of the 2nd test.  I think I was probably spot on at about 0.895 inches per test.  0.895/0.919 = 2.61%