Topic: New Climalytic TROPO gauge installed

[ValentineWeather]

I'll be sticking with the original Cocorahs Stratus model it's closer to the Official 8". So because many have complained the new Tropo reads low they've decided all the Stratus models read high 2.5% and they've known it all along which I find ridiculous.
 
The 8" has always recorded more or the same vs the Stratus. This is just a Red Herring to distract from the bottom line, the new Tropo model measures 4% low vs the 8" SRG. This comparison above was a substantial rainfall so a good sample size plus a low wind event and no reason the results aren't true.

I don't think the 2-8" diameter gauges are wrong. 

[CW2274]

I don't think the 2-8" diameter gauges are wrong.

Granted, my RW bucket (which you turned me onto) isn't the caliber of your tippers, (although, 2% accuracy is nothing to sneeze at) but I still use it as my "official" measurement. I'm sure I get a lot of over that, but I calibrate it like I own it.   I'll take a properly calibrated 8" catch over a 4" any day.

Thanks for the data points....again.   

[ValentineWeather]

I don't think the 2-8" diameter gauges are wrong.

Granted, my RW bucket (which you turned me onto) isn't the caliber of your tippers, (although, 2% accuracy is nothing to sneeze at) but I still use it as my "official" measurement. I'm sure I get a lot of over that, but I calibrate it like I own it.   I'll take a properly calibrated 8" catch over a 4" any day.

Thanks for the data points....again.   

I'm using two manual 8" gauges, one of them is the actual Official NWS (SRG) used across the country at airports, Coops, and NWS offices. So it's the real McCoy you might say. I also have the matching measuring stick. It looks like I may be taking over the Valentine Coop with the MMTS.  Because this was one of the Forecast offices that got closed they want to make sure snowfall continues to get measured. Right now it's being contracted out but that may be changing soon should I take over.   That being said the Tropo matched the NWS SRG this afternoon both (.13") Go figure...

[CW2274]

I don't think the 2-8" diameter gauges are wrong.

Granted, my RW bucket (which you turned me onto) isn't the caliber of your tippers, (although, 2% accuracy is nothing to sneeze at) but I still use it as my "official" measurement. I'm sure I get a lot of over that, but I calibrate it like I own it.   I'll take a properly calibrated 8" catch over a 4" any day.

Thanks for the data points....again.   

  That being said the Tropo matched the NWS SRG this afternoon both (.13") Go figure...

Ma Nature loves jacking with us...

[WheatonRon]

I don't think the 2-8" diameter gauges are wrong.

Granted, my RW bucket (which you turned me onto) isn't the caliber of your tippers, (although, 2% accuracy is nothing to sneeze at) but I still use it as my "official" measurement. I'm sure I get a lot of over that, but I calibrate it like I own it.   I'll take a properly calibrated 8" catch over a 4" any day.

Thanks for the data points....again.   

I'm using two manual 8" gauges, one of them is the actual Official NWS (SRG) used across the country at airports, Coops, and NWS offices. So it's the real McCoy you might say. I also have the matching measuring stick. It looks like I may be taking over the Valentine Coop with the MMTS.  Because this was one of the Forecast offices that got closed they want to make sure snowfall continues to get measured. Right now it's being contracted out but that may be changing soon should I take over.   That being said the Tropo matched the NWS SRG this afternoon both (.13") Go figure...

My guess, and undoubtedly your guess too Randy, the measurements from your Tropo and your NWS gauge would have differed had the rain total been more substantial, like an inch or so. Like you, I will stay with my Stratus gauge for my CoCo reporting—I do the best job I can with trees, etc., in my yard, but I won’t cut down any trees to achieve better accuracy! I think most people migrating to the Tropo gauge will be fooled or disappointed, unless they don’t have trees (or other obstacles) anywhere near their gauge—what little improvement in accuracy these folks are achieving with such an “upgrade”!

[ocala]

This a comparison of an old stratus, 2008, versus a new one 2022, and a new Davis tipper.
Old    .42/.02/.50
New   .41/.02/.48
Davis-.45/.02/.56
These are mounted on a 4x4 6 inches apart.

[Cutty Sark Sailor]

Well, Randy, et.al.  ...   I kept telling myself I was going to observe and not respond or comment any further... but what the hell?...

,,,,So because many have complained the new Tropo reads low they've decided all the Stratus models read high 2.5% ...

This appears to me to be mis-represented and backasswards. The Stratus claims a 4" collector. If that's a fact, whatever it drips into, one inch of water must volume ±205.5ml and mass ±205.5gm at 70°F.  Using 206 as unit sort of simplifies the averages. I personally have NOT decided that 'ALL Stratus models read high...'  But I DO KNOW that EACH different Stratus I possess, going back 16 years or so  (which I've retained for some silly reason or other),  express different numbers for what should be 206gm~206ml /inch. They ALL vary from 198 to 201. The tare weight varies also. The scale graduations are NOT consistent between tubes. The overflow slot is unpredictable between tubes. This results in physical errors that vary mathematically from 2.5 to 4 percent over-report for a device supposedly calibrated for 4" collector and 1" cylinder, and in fact when 1"indicated stratus decants into two different Tropo tubes, both Tropo tubes report less volume, and the same exact numbers are CONFIRMED with 2 different digital scales, and with quality glass lab cylinders used as reference baseline for calculated mass/volume. And furthermore, on many of my Stratus cylinders, the error by mass/volume approached 10% on lower 'depths' computing gm or ml!  Many of us noted the Stratus inconsistency, beginning with the overflow slot variance perhaps, and started commenting about it, and folks stated checking, etc.

...and they've known it all along which I find ridiculous.

Well, I do agree that a claim of 'known it all along' is a bit of a stretch.  I'm not sure I've run into anyone who has stated that, however, and I certainly didn't.  Apparently for the first 40 years, things were apparently well with Stratus production consistency, and accuracy.  I suppose someone who began using a Stratus 5-10 years ago may have 'known it all along'.  I personally started noting question points with the Stratus I obtained about 6 years ago, and the quality control, including the transparency of the Stratus material has varied all over the place with parts I've received since then.

I don't think the 2-8" diameter gauges are wrong.

Ok.  I agree, the NWS 8" SRG is the gold standard.
Then this must follow:
If I've done the math correctly, one inch in the 8" gauge should be ±824gm ~ ml, or, (Why, imagine this!) 4 times 206gms and 206ml!!!.  I don't own a NWS 8" gauge, so I can't physically check that, but I took the TROPO inner cylinder, filled it to one inch 4 times. Repeated a few times, because I was a little bit surprised... Can you  guess the results?  Yep. Surprise!  By magic, the actual measurements were ± 823-825gm and ± 823-825ml. Per scale, per lab cylinder.  ...sigh.

This is just a Red Herring to distract from the bottom line, the new Tropo model measures 4% low vs the 8" SRG. This comparison above was a substantial rainfall so a good sample size plus a low wind event and no reason the results aren't true.

Ahem.  I'll state it firmly... No! The Tropo doesn't measure 4% low vs 8" NWS SRG... IF the EXACT same number of identical drops fall into the two collectors, and if both are constructed per specs, and not damaged, dirty, whatever!!! In the case of the TROPO the inner cylinder graduations are calculated to be precise per gm~ml equivalent, laser cut AFTER molding.  BOTH gauges should, in fact, agree. I just illustrated that mathematically, and with calculated volume and mass physical measurements that the Tropo and the 8" NWS SRG are designed equivalent, and physically shown that the TROPO corresponds with the calculated amounts...

You are, of course, aware that a 'Red Herring' is simply an over-smoked and salted regular herring, right? I personally don't fancy an English breakfast with kippers, whatever color, however. 

The actual facts behind the development of one alternative to the Stratus, what became the Tropo, can be traced back to "WeatherFlow" research from about 2016, and released to 'private' sector in 2021.
https://uploads-ssl.webflow.com/6273f802e4834effc055005d/6468d7ca36a65a717dcaf06a_TROPO%20history%20-%20Climalytic%20Presentation%20(WERA%2C%2017May2023).pdf

[ValentineWeather]

I've let Steve Hilberg know my feelings. I've had the Stratus and 8" SRG side by side since 2014. Just recently let my last Stratus go where I thought it would be served best since I had the two 8" SRG's.
This is not true if it were then the 8" SRG is wrong. I refuse to believe it because that's not what I've seen. Had I known it was going to be claimed, I'd of kept meticulous records. If anything it's the other way around.
 [ You are not allowed to view attachments ]

I'm done with the thread have fun weighing water.

[PaulMy]

Cutty Sark Sailor wrote:
The actual facts behind the development of one alternative to the Stratus, what became the Tropo, can be traced back to "WeatherFlow" research from about 2016, and released to 'private' sector in 2021.
https://uploads-ssl.webflow.com/6273f802e4834effc055005d/6468d7ca36a65a717dcaf06a_TROPO%20history%20-%20Climalytic%20Presentation%20(WERA%2C%2017May2023).pdf

Thanks for that link, very informative.
I am waiting for CoCoRaHS Canada to let me know when they expect to receive stock.  Hopefully they will offer some discounted pricing like they do for the current Stratus.


Enjoy,
Paul

[Climalytic]

Hello from Climalytic Instruments. It’s great to see all of the discussion of the TROPO. We do want to clarify a few things.

The most trusted, scientific comparison between the NWS 8” SRG and the Stratus is this paper by Nolan Doesken, the CoCoRaHS founder himself. The 10-year comparison study found that the 4-inch Stratus gauge consistently measured higher than the 8-inch gauge by about 3 percent. A similar study is being conducted by the Colorado Climate Center at CSU, this time including the TROPO. Until the findings of these observations are available, mathematics today prove the TROPO is more accurate than the Stratus, and likely within +/-1% of the 8” SRG.

The founder of Climalytic Instruments, Tye Parzybok, has known Nolan and the Colorado Climate Center staff since the late 1980s, and has been a CoCoRaHS observer since the conception of CoCoRaHS itself. Our team has worked closely with CoCoRaHS every step of the way in the design and testing of the TROPO gauge. We consider our close relationship with CoCoRaHS staff and observers to be invaluable.

We understand that our pricing may seem high, but please understand that we have done our best to make the TROPO as affordable as possible, while also ensuring that we deliver a premium product. Our goal is to run a sustainable small family business while providing needed innovations to legacy weather instruments. We are also actively pursuing resellers in Canada and Europe to help lower the cost of international orders.

Thanks for your support!

[WheatonRon]

Hello from Climalytic Instruments. It’s great to see all of the discussion of the TROPO. We do want to clarify a few things.

…

Thanks for your support!

Great post and good luck with your product. Whether people (weather amateurs or enthusiasts) will be willing to pay a significantly higher price for precision that probably most folks can’t achieve because of physical limitations on their property remains to be seen. For example, last week I had some rain at my house. One of my Stratus gauges measured .40 the other was .34–the gauges are about 50 feet apart. Trees on my property slightly interfere with both gauges but since the rain fell at night, under gusty conditions, not sure which one was more accurate but I chose the .40 reading to report my daily rain measurement. My point is, probably most CoCo reporters are average folks like me with yards that have trees or other obstacles that could affect rain measurements. The 3% high error rate in the Stratus gauge doesn’t seem unreasonable but when considering the other variables (trees, etc.) we must face getting more precision of a measurement seems a bit much. For users having to deal with snow in the winter—the measuring of precipitation has even more estimates involved and the Tropo gauge won’t significantly help that job.

[CW2274]

Hello from Climalytic Instruments. It’s great to see all of the discussion of the TROPO. We do want to clarify a few things.

…

Thanks for your support!

The 3% high error rate in the Stratus gauge doesn’t seem unreasonable but when considering the other variables (trees, etc.) we must face getting more precision of a measurement seems a bit much.

Not to be an ass, then don't buy it. I'm sure there are folks here that don't have "normal" people's limitations in this manner, and want a more touted gauge. Whether or not it deserves praise, I personally have no idea other than what's stated here, but the choice is available for those that do.

[Climalytic]

Whether people (weather amateurs or enthusiasts) will be willing to pay a significantly higher price for precision that probably most folks can’t achieve because of physical limitations on their property remains to be seen.

Perhaps, but in addition to the improved accuracy, the TROPO improves on the Stratus in many other ways. In fact, the non accuracy related improvements are the real selling point for most people. These include:

• an easy and versatile mounting solution
• a taller cap that snaps on
• bird spikes
• a stabilizing base and funnel top for the inner cylinder
• a taller inner cylinder that's easier to read
• an outer cylinder with a greater capacity
• a pour spout on the outer cylinder
• UV resistant polycarbonate
• both metric and imperial gradations
• accessories like a cleaning brush and handle
• it looks cooler

The "Premium CoCoRaHS Gauge" isn't for everyone, but many have found the quality-of-life improvements to be worth the price.

[openvista]

So I removed my Stratus inner cylinder and weighed exactly 1" of water (according to the marks on the inner cylinder). It weighed 202 grams which is about 4 grams short of an actual inch. So when the inner cylinder reads 1", there's only 0.98" in that particular cylinder. I don't have another cylinder for comparison.

Another BIG problem is that CoCoRaHS has been telling everyone as far back as I can see that 1" of water weighs 201 grams. You can see that on the attached image from a PDF on their website called "Alternative Methods for Making CoCoRaHS Snow Water Content Measurements" (see: https://media.cocorahs.org/docs/CAN/CoCoRaHS%20Alternative%20Methods%20to%20Snow%20Measuring%20Oct%202014%20RF.pdf). I also found it here: https://www.cocorahs.org/Content.aspx?page=Hilbergstips. I know I've seen it elsewhere. I've NEVER seen them say it's 206 grams until I read it reported here. I suspect that's a recent edit to their site.

That calculation factor error, all by itself, even if one weighs snow/rain properly, will result in a 2.5% over reporting of precipitation!!

Furthermore, I suspect that the manufacturer of the Stratus might have been told that 1" of water = 201 grams. That being the case, then the manufacturing differences reported here between Stratus gauges would seem more "acceptable" (when using the wrong reference standard).

All of this seems very inexcusable for a simple fact (the weight of a given volume of water) that is easily verifiable and has been known for how long now?

[openvista]

Here's CoCoRaHS 2021 Winter Reporting Guide telling people that 1" of precipitation = 201 grams

See: https://media.cocorahs.org/docs/CT%2FSNE%20CoCoRaHS%20Winter%20Reporting%20Guide.pdf

Like I said, I've never seen 206 grams as the reference point for an inch of liquid in their 4" gauge.

***

UPDATE: I also found this same error on their training PDF "Measuring the Water Content of Snow By Weight" (see pg 5: https://media.cocorahs.org/docs/Training_SnowByWeight.pdf)

UPDATE 2: 201g seen again in the 2022 Winter Precipitation Measurements PDF

[WheatonRon]

So I removed my Stratus inner cylinder and weighed exactly 1" of water (according to the marks on the inner cylinder). It weighed 202 grams which is about 4 grams short of an actual inch. So when the inner cylinder reads 1", there's only 0.98" in that particular cylinder. I don't have another cylinder for comparison.

Another BIG problem is that CoCoRaHS has been telling everyone as far back as I can see that 1" of water weighs 201 grams. You can see that on the attached image from a PDF on their website called "Alternative Methods for Making CoCoRaHS Snow Water Content Measurements" (see: https://media.cocorahs.org/docs/CAN/CoCoRaHS%20Alternative%20Methods%20to%20Snow%20Measuring%20Oct%202014%20RF.pdf). I also found it here: https://www.cocorahs.org/Content.aspx?page=Hilbergstips. I know I've seen it elsewhere. I've NEVER seen them say it's 206 grams until I read it reported here. I suspect that's a recent edit to their site.

That calculation factor error, all by itself, even if one weighs snow/rain properly, will result in a 2.5% over reporting of precipitation!!

Furthermore, I suspect that the manufacturer of the Stratus might have been told that 1" of water = 201 grams. That being the case, then the manufacturing differences reported here between Stratus gauges would seem more "acceptable" (when using the wrong reference standard).

All of this seems very inexcusable for a simple fact (the weight of a given volume of water) that is easily verifiable and has been known for how long now?

Somewhere on the CoCoHaRS website it states that 1” of water equals 206 grams. So when I find that page, I will provide a link. In short, there is a discrepancy.

[openvista]

Somewhere on the CoCoHaRS website it states that 1” of water equals 206 grams. So when I find that page, I will provide a link. In short, there is a discrepancy.

You may have more luck than me finding this as I did a Google site search of CoCoRaHS. If you go to Google and type "site:cocorahs.org" then put a space and search for "206g" or "206 g" or "206 grams". I got nothing. Then I tried "201g" and all kinds of results popped up!

The problem here is even if you find one place on the CoCoRaHS website that says 206g = 1" of water they have put the 201g figure in their training videos and PDFs for years. I have noted 5 PDFs with errant info already in my two previous posts. So even those of us who weigh precipitation, since that is the most accurate/foolproof method bypassing manufacturing issues with the inner cylinder, have been given the wrong conversion factor. The net result, regardless of how you choose to measure, is a 2.5% over reporting of precipitation based strictly on actual gauge catch.

It is not difficult to determine the weight we've been supplied is wrong. As Cutty Sark Sailor already pointed out, basic grade school math tells us what the volume should be:

height * pi * radius squared

which works out to be:
2.54 cm (height of 1" of water) * 3.14159 (pi) * (5.08*5.08) = 205.93

And because 1 cubic cm = 1 gram we know that 1" of water in a 4" cylinder should equal 206 g (rounded up).

[PaulMy]

The way I read it is that in the past CoCoRaHS has indicated that 1" of rain in the Stratus inner tune is 201g (200.8 )

one example from CoCoRaHS publications is Hilberg's Tips in 2019
Your outer cylinder plus the snow in it weighs a total of 510 grams. The outer cylinder weighs 445 grams. The weight of the snow in the gauge is 510-445 = 65 grams. 65 g divided by 201 g/inch = 0.32 inch of precipitation.

What is now being said that actually 1" of water in a Topo tube is 206g (205.926)

from May 25, 2023 "A New Rain Gauge Option for CoCopRaHS"
How Accurate is the Tropo Gauge?The Stratus gauge has a known error of about 2.5 percent (reads 2.5 percent too high). That is within the stated NWS error range of 4 percent from the 8-inch standard rain gauge. The Tropo gauge is accurate to less than 1 percent error. This accuracy is determined by measurement.The volume of water of a “disc” one inch high and 4 inches in diameter (the outer cylinder) is 205.926 ml (cm3), and it's mass is 205.926 grams. We know there is an error in the Stratus gauge because the volume of water filled to the one inch mark on the inner measuring tube weighs 200.8 grams, not 205.9 grams. A 10-year comparison study of the 4-inch gauge and the NWS 8-inch rain gauge by the Colorado Climate Center found that the 4-inch gauge was higher than the 8-inch gauge by about 3 percent each year. That is consistent with the known accuracy of the Stratus 4-inch gauge.

I am assuming that in the past CoCoRaHS considered the +2.5 bias in the Stratus and for measuring by weight reduced the supposedly 1" of rain by that 2.5% bias from 206g to 201g thus giving the weighing method a more accurate SWE measurement.

For my comfort in measuring snowfall and snow depth SWE, not a big deal as my capturing of snow is not that precise!
And for measuring the daily rain, I have some difficulty in actually reading the amount of rain in the inner tube to anything more accurate than in-between the 0.2 mm increments.

My 2 cents worth.  and I will get the new Topo if there is a fair $Canadian dollar cost.

Enjoy,
Paul

[openvista]

I am assuming that in the past CoCoRaHS considered the +2.5 bias in the Stratus and for measuring by weight reduced the supposedly 1" of rain by that 2.5% bias from 206g to 201g thus giving the weighing method a more accurate SWE measurement.

I think this is a misunderstanding. When you reduce a divisor (201 instead of 206), it INCREASES the quotient (resulting number).

Let me put this differently. There are two types of observers. Either you:

1. Measure 1" of water using the inner cylinder visually using the tick marks

--- OR ---

2. You remove the inner cylinder and weigh 1" in the outer cylinder (dividing the result by the weight of a reference point such as 1" of water = 201g)

Either way you get a 2.5% over measurement based on either the cylinder being marked incorrectly or using the wrong divisor for weight (201 supplied by CoCoRaHS).

It's one or the other. CoCoRaHS isn't correcting for anything with the 201 number they've supplied for observers who weigh their precipitation (since they don't use the inner cylinder). Instead CoCoRaHS is REPLICATING the same error across both calculation methods. Regardless of how you've chosen to report what falls in your Stratus gauge, your report will be high by the same amount.

Also any 4" gauge, whether it's Tropo or Stratus, will have the same conversion factor. 1" of rain will always equal 206g (not including extremes in air/liquid temp). It has nothing to do with the gauge and is strictly based upon math for a 4" diameter cylinder.

[CW2274]

Well, I thought I'd stir the pot here with today's lovely, sometimes wind driven rain. Comparison of two Stratus's, and two hand calibrated (by me) 8" RW tippers.

Older Stratus inner tube... 200 grams = 1.00" of rain...    0.70" measured.

Newer Stratus inner tube... 204 grams = 1.00" of rain...   0.69" measured.

RW tipper #1.... 0.74" measured.

RW tipper #2.... 0.73" measured.

Give or take, this is a typical result that I've seen when it rains enough to get something meaningful.

This concludes this evening's pot stirring.

[ocala]

CW that goes along with my findings.
Have had rain 13 days in a row. The older stratus measured more rain all but one time. So which one is accurate.
They are both mounted on the same 4x4. I just posed that question to Coco in an email.

[jerryg]

finally got some rain down here, i have my three gauges within 3 feet of each other for comparing readings. The rainfall rate at times was up to 9 inches an hour and very windy with peak wind at 54 mph so real good test conditions. My 8 inch gauge and cocorahs gauge both recorded 1.23 inches while the tropo showed 1.18 inches. On the cocorah gauge i added another funnel with the bottom cut off to help with the splash out in heavy rain and it seems to have worked real well. My tropo in light rain and low wind seems to read the same as the cocorah and 8 inch gauge. Will have to wait for another heavy rain and wind event to see if i get the same results.

[ValentineWeather]

My 8 inch gauge and cocorahs gauge both recorded 1.23 inches while the tropo showed 1.18 inches.

Thanks for the feedback, Jerry. And wouldn't you know it, the same -4% low. (1.23 minus 4%= 1.18)
Also, see similar results as you where the lighter rains gauges come in the same but the big boys that -4% shows it's ugly head.

[openvista]

I received the new Tropo gauge last week. The inner cylinder weighs 123 grams empty. When filled with 1" of water it weighs 329 grams. Therefore, the water inside (once you subtract the weight of the inner cylinder) weighs exactly 206 grams as expected.

As posted earlier, the inner cylinder in my Stratus gauge filled with 1" of water weighed 293 grams (inner cylinder itself weighs 91 g) which produces 202 g of actual water which amounts to only 0.98". So reporting 1" from that particular Stratus would represent a 2% high measurement.

People keep mentioning field measurements. This is apples and oranges. What Cutty Sark Sailor and I are saying is that the exact same volume of water poured into these gauges measures EMPIRICALLY differently based on how the two gauges are manufactured.

Whether the old 4" Stratus gauge's high bias (admitted by CoCoRaHS) causes it to measure *functionally* consistent with the 8" Standard Rain Gauge in the field is a completely separate discussion that obscures the main issue. The Tropo appears to fix a manufacturing defect in the Stratus gauge.

I would expect the 8" SRG to collect more. First, it is mounted lower and has a wider aperture that collects more precipitation, especially snowfall, in windy conditions. For a 4" gauge mounted at least 2 ft higher to perform similarly, it would likely need a positive correction factor (which would depend on how much snowfall and/or wind a given site receives).

[jerryg]

This is what my comparison shows, i did some static comparisons indoors are the results are like you show but the real test is the ability to accurately catch the rainfall with all rates of rainfall and winds. The tube can be really accurate in showing 1 inch but if the gauge is having trouble with the catching of rain do to various conditions, that is the real test. If the gauge has trouble in heavy rains then the catch not the tube is showing an error. I use my eight inch gauge because it performs much better and is more accurate than the four in gauges. The tropo has shown to be accurate with light to moderate rainfall and compares to the eight inch quite well but with heavy rain it suffers the same as the Stratus. My stratus would under count in heavy rains too but with the added cap to deepen the funnel and prevent the funnel from filling up and causing splash out thus lower reading. In heavy rain the funnel fills up faster than the water drains into the tube causing the lower reading than the much larger funnel of the eight inch which has a larger opening for the water to drain faster. This is just what i have seen so far and will continue to do comparison in various rain events.