Author Topic: WH40 vs WH65 Rain Measurements  (Read 1781 times)

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Offline GHammer

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WH40 vs WH65 Rain Measurements
« on: April 09, 2020, 03:03:45 PM »
I have both the WH40 rain gauge and the rain gauge that is part of the WH65 Osprey.
Both are mounted clear of obstructions. The WH40 is about 18 inches off the ground over grass. The WH65 is mounted at 33 feet.

Today, the wh40 is showing 0.32 inches while the WH65 is showing 0.43

They have had that relationship in measuring since the WH40 was installed, meaning it always records less rain than the WH65.

I suppose I'll have to get a manual gauge and see which is the more accurate, meantime, anyone have an idea which gauge should be more accurate?
Ecowitt HP2551-C, GW1000, WS68, WH40, WH32-EP, WH32B, RS0001

Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #1 on: April 09, 2020, 03:46:27 PM »
The WH40 is sold by Ecowitt and advertised as "High Precision." Also the WH40 has a larger diameter. It is well known that a larger diameter rain gauge tends to be more accurate. Of course anyone can build a large diameter rain gauge that is garbage. Some of the more reputable weather station brands that are more expensive all use large rain gauges. Then take a look at airport rain gauges...they are quite large. So my take is that the WH40 should be better than the WH65.

Also 33 ft is not ideal for a rain gauge. Maybe that is the problem. But I surely would do like you have said, and get a Stratus manual gauge as that is a good reference.
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Offline kd7eir

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Re: WH40 vs WH65 Rain Measurements
« Reply #2 on: April 09, 2020, 03:58:10 PM »
There is no guarantee that the rain seen at 33 feet actually makes it to the ground. Look at composite reflectivity radar which shows the moisture in the air vs base reflectivity radar which is showing the moisture that makes it to the ground - normally there is a huge difference. A lot can happen to a rain drop in 31.5 feet.

Offline mauro63

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Re: WH40 vs WH65 Rain Measurements
« Reply #3 on: April 09, 2020, 05:21:49 PM »
the most common and most bigger error on rain measurement is the wind turbulence, more height more wind, more wind more turbulences, the turbulences due to the wind impact on the rain collector can increase the measurement error, stronger the wind, higher will be the rain underestimation

Mauro

Offline Rover1822

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Re: WH40 vs WH65 Rain Measurements
« Reply #4 on: April 09, 2020, 06:57:16 PM »
the most common and most bigger error on rain measurement is the wind turbulence, more height more wind, more wind more turbulences, the turbulences due to the wind impact on the rain collector can increase the measurement error, stronger the wind, higher will be the rain underestimation

Mauro

I'm not saying you are wrong, however these sensors ( the bucket tilt units)  are meant to get you an average/estimated  rainfall for the immediate  area. Of course they are not perfect. Also with  "turbulent" wind which has many descriptions depending on context (for me means and irregular or disrupted wind pattern) your statement of "more height more wind, more wind more turbulences"  does not fall in within my understanding and knowledge of wind turbulence. Typically it gets worse closer to the ground as ground features disrupt wind, causing turbulence. If what you propose is true than we would all build our wind turbines at ground level. But OK semantics aside on the use of the word turbulence,  the basic premise  is that the rain will fall at some point in your collector.. hence the average, or estimated concept.
« Last Edit: April 09, 2020, 07:15:20 PM by Rover1822 »
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Offline GHammer

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Re: WH40 vs WH65 Rain Measurements
« Reply #5 on: April 09, 2020, 07:50:45 PM »
Thanks to all.
My take away here is that until I get a manual gauge, I shall take the WH40 as accurate.
It is the recommended height and surface for rain measurement, is larger, and for some silly reason, I usually equate separate with better. Though that is certainly not always true, it's been a good rule of thumb for me.

Hoping you are all well and riding out the various restrictions of the times.
Ecowitt HP2551-C, GW1000, WS68, WH40, WH32-EP, WH32B, RS0001

Offline mauro63

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Re: WH40 vs WH65 Rain Measurements
« Reply #6 on: April 10, 2020, 04:20:27 AM »
the most common and most bigger error on rain measurement is the wind turbulence, more height more wind, more wind more turbulences, the turbulences due to the wind impact on the rain collector can increase the measurement error, stronger the wind, higher will be the rain underestimation

Mauro

I'm not saying you are wrong, however these sensors ( the bucket tilt units)  are meant to get you an average/estimated  rainfall for the immediate  area. Of course they are not perfect. Also with  "turbulent" wind which has many descriptions depending on context (for me means and irregular or disrupted wind pattern) your statement of "more height more wind, more wind more turbulences"  does not fall in within my understanding and knowledge of wind turbulence. Typically it gets worse closer to the ground as ground features disrupt wind, causing turbulence. If what you propose is true than we would all build our wind turbines at ground level. But OK semantics aside on the use of the word turbulence,  the basic premise  is that the rain will fall at some point in your collector.. hence the average, or estimated concept.

the most accurate rain measurement is near the ground or, better, exactly at the ground, so to reduce the wind turbulence due to the wind impact with rain collector cone, this is not my opinion, this is a rule
the wind shield used in professional weather station solve partially the problem when the rain collector is above the ground
the wind increase with height

Mauro
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Offline Rover1822

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Re: WH40 vs WH65 Rain Measurements
« Reply #7 on: April 10, 2020, 09:56:26 AM »
I see your point, thank you Mauro
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Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #8 on: April 10, 2020, 10:40:52 AM »
I'm thinking we all need an upgrade like this...

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Offline GHammer

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Re: WH40 vs WH65 Rain Measurements
« Reply #9 on: April 10, 2020, 10:50:14 AM »
I'm thinking we all need an upgrade like this...


Shipping cost from China may be prohibitive, I'll check with Lucy though.  :lol:
Ecowitt HP2551-C, GW1000, WS68, WH40, WH32-EP, WH32B, RS0001

Offline Rover1822

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Re: WH40 vs WH65 Rain Measurements
« Reply #10 on: April 10, 2020, 10:51:38 AM »
LOL
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Offline mauro63

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Re: WH40 vs WH65 Rain Measurements
« Reply #11 on: April 10, 2020, 02:16:46 PM »
I'm thinking we all need an upgrade like this...

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Not necessariy in amateur weather station but a good setup


Mauro

Offline platokidd

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Re: WH40 vs WH65 Rain Measurements
« Reply #12 on: May 25, 2020, 09:45:27 PM »
I just purchased the WH40 (ambient) to go a long with my WS-2000 (wh65)

In 4 rainy days logged, the wh40 always reads less and once not at all.

Wh40      wh65   day of rain
.00           .04      1  Yes it rained very light all day.
.32          .47       2
.11          .14       3
.30          .40       4
wh40 is about 5 feet off the ground. wh65 is about 30 feet off the ground.
The wh65 compares better to other pws in my area and the wh40 does not.

Does the wh40 need to be calibrated?  I have removed the filter spring but see little difference. From my view point the wh65 is more accurate.
« Last Edit: May 28, 2020, 11:23:04 PM by platokidd »
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Offline platokidd

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Re: WH40 vs WH65 Rain Measurements
« Reply #13 on: June 28, 2020, 09:48:29 PM »
Thought I would give an update here on Ambients version of the wh40.

Side by side now with ambient's version of the wh65 (ws-2000 or ws-2902a/b)

Ambient's  version  of the wh40 constantly under reports rain. Right now I'm trying to adjust the offset to be some what accurate.

The wh40 does have a larger funnel for the rain sensor. Monitored during a heavy rain and getting soaked, comparing the wh65's rain sensor to the wh40 senor , most of the rain just bounces of the wh40. Have to think the oversized rain funnel is a trampoline for rain to bounce off of. The shallower angel of the the funnel is a launching pad for rain.

Over all opinion now, I would not have spent the money on the wh40. Hinddsight is 20/20.

 


 
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Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #14 on: June 28, 2020, 10:04:12 PM »
Hmmm...you are not the first person to have noticed this. Darn.

Maybe Fine Offset/Ecowitt can design a new funnel. I'm going to suggest it to them. It is such an easily replaceable part that this seems like a no brainer.

I can even see someone with 3D design and 3D printing experience to come up with a better funnel. I would start by scanning the original funnel. Then once scanned you elongate the funnel and make it taller. You don't even need to worry about changing the slope of the inside funnel. Only the walls need to be taller.

I can see also a DIY fix of wrapping some plastic to make a tall wall and then figuring out a way to make sure that the inside lip isn't a catch for water to get stuck...and also making it so that the top diameter is the same as the original funnel.
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Offline Mandrake

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Re: WH40 vs WH65 Rain Measurements
« Reply #15 on: June 29, 2020, 03:15:42 AM »
This is an interesting engineering challenge that is not obvious on paper but only becomes apparent in certain weather conditions.
As you say its something that can and should be possible to resolve given that the funnel is just a plastic part.
I am wondering if someone simply wrapped cellophane or equivalent around a set of bird spikes whether that would be enough to capture the rain splatter.

Hopefully the next generation haptic rain sensor in the works will be able to benefit from these observations.
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Offline GHammer

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Re: WH40 vs WH65 Rain Measurements
« Reply #16 on: June 29, 2020, 01:57:51 PM »
I hope when a new funnel is made that existing owners can get one easily.

Makes me wish a had a scanner and 3D printer.
Dupilcate it with 2 inch higher walls.
Ecowitt HP2551-C, GW1000, WS68, WH40, WH32-EP, WH32B, RS0001

Offline funsutton

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Re: WH40 vs WH65 Rain Measurements
« Reply #17 on: June 29, 2020, 02:09:59 PM »
Hmmm...you are not the first person to have noticed this. Darn.

Maybe Fine Offset/Ecowitt can design a new funnel. I'm going to suggest it to them. It is such an easily replaceable part that this seems like a no brainer.

I can even see someone with 3D design and 3D printing experience to come up with a better funnel. I would start by scanning the original funnel. Then once scanned you elongate the funnel and make it taller. You don't even need to worry about changing the slope of the inside funnel. Only the walls need to be taller.

I can see also a DIY fix of wrapping some plastic to make a tall wall and then figuring out a way to make sure that the inside lip isn't a catch for water to get stuck...and also making it so that the top diameter is the same as the original funnel.

This is a bit disconcerting as I was planning to upgrade to the WH40 as well as the WH80 whenever Ambient gets  them in. Now I wonder if I should just do the WH80 and keep the osprey as my rain gauge.

Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #18 on: June 29, 2020, 02:22:25 PM »
You mean WS80 not WH80...but yes.

I'll let you know what Ecowitt responds regarding the WH40. It might be a while as I'm sure we need to give some time to their engineers to do some testing and verification.

You can certainly keep the WH65 as your rain gauge and then just upgrade the anemometer and temperature/humidity sensors.
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Offline funsutton

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Re: WH40 vs WH65 Rain Measurements
« Reply #19 on: June 29, 2020, 02:46:30 PM »
You mean WS80 not WH80...but yes.

Ambient's website led me astray:

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https://help.ambientweather.net/help/sensor-abbreviations-for-ws-2000-c-display-console/

Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #20 on: June 29, 2020, 02:50:19 PM »
Ok sheez! Figures it was a reseller issue. Ecowitt calls it WS80. Got it now, Ambient WH80. I just don't know why they play these games like we aren't going to realize it is all the same thing.

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Offline funsutton

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Re: WH40 vs WH65 Rain Measurements
« Reply #21 on: June 29, 2020, 02:55:37 PM »
Make of this what you will, but this is directly from the WS-2000 console:

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Offline galfert

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Re: WH40 vs WH65 Rain Measurements
« Reply #22 on: June 29, 2020, 03:20:01 PM »
Make of this what you will, but this is directly from the WS-2000 console:

Wow too funny!

I had known for some time, from having access to the GW1000 API, that internally the WS80 is really a WH80. That is just what the sensor is called within the official API documentation. I guess from this point on it will be called both. I had refrained myself from ever using WH80 so as to not cause confusion. It appears now the cat is out of the bag and it will forever unfortunately be confusing for new users. Oh well.
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Offline Mandrake

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Re: WH40 vs WH65 Rain Measurements
« Reply #23 on: June 30, 2020, 03:17:44 AM »
Yes, I am not sure why Ecowitt do that...
When it was first created and I had a test unit delivered it was a WH80 but subsequently they referred to it as WS80 and we all adopted that name.

It certainly makes our lives a little trickier as the number of sensors and variants increase!
Retired: Old Maplin N96Y/FO Weather station
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Ecowitt HP2550A + WH65 (Wunderground: IGUILDFO67)
Ecowitt GW1000 (Wunderground: IGUILDFO68)
Ecowitt GW1000 (Mk2) test environment driving CumulusMX on a RPi 3b
Ecowitt WH51 (x4) Soil Moisture Sensor
Ecowitt WH41 PM2.5 AQM Sensor
Ecowitt WH31 (x8) Thermo/Hygro Sensor
Ecowitt WS80 Ultrasonic Anemometer (pre-prod test)
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Offline ns99

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Re: WH40 vs WH65 Rain Measurements
« Reply #24 on: July 21, 2020, 12:17:01 PM »
Purchased the Ecowitt HP2553 which includes the WH40 I believe. Since installation there have been 6 rain events and the WH40 under reported 4 times - approx. 1/3 of local - 5km - international airport. (that is WH40 4.6mm, airport 15mm) Other PWS in area reported similar values as the airport. The WH40 is 120cm off the ground 5-6m clear of any buildings / trees.

As suggested in the manual I have caught the rain exiting the WH40 and measured it. In all cases of suspected under report, the rain exiting has been more that what was recorded according to calibration formula in the manual.

I've been in conversation with support (Lucy) and very helpful, but no solution. I was told by Ecowitt that the WH40 will only count max 50 tips in single reporting period of 49 sec.

Since the rain events that resulted in under reporting were heavier (not talking flash flood level, but 20 min drenching) I believe that the design will incorrectly report during rain events exceeding 6-8 mm/hr. Example if 51 tips occur in 49 sec, only 1 tip is reported. According to Ecowitt 50 tips in 49 secs = 8mm/hr.

I am very surprised that a WH40 would be this poorly designed so I'm sure something else must be wrong. However Ecowitt support has no remedy.

Am I missing something, or is the WH40 really that poorly designed?

 

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