Author Topic: Metergroup ATMOS-41 Weather Station - anyone know anything about these.  (Read 7697 times)

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Offline Ann_Brush

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Has anyone seen one of these or have any comments about them - supposed to be a low cost, accurate, no moving parts, robust, low end professional Wx Sta. Looks very intriguing.
http://www.metergroup.com/environment/products/atmos-41/
I was looking on Wundergroung and clicked on a wx. sta. in Chad Africa, noticed that the hardware was "TAHMO" and had never heard of them - did some digging and the website popped up. Tahmo is an African wx project.

Offline CW2274

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This is nothing more than another Netatmo. Without a proper radiation shield, it will be worthless in the sun, so shade will need to be constant for any kind of accuracy. Good luck with that.

Offline Ann_Brush

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I don't think its close to a Netatmo at all. Its not in the same league re accuracy specs (which are pretty decent) and it certainly isn't price wise. US pricing for ATMOS-41 (I emailed the company) is USD 1600.00 (March 2017) for the station alone.

Offline mwall

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it looks like decagon hardware.  they make some of the best soil moisture sensors you can buy.  apparently they are branching out into complete weather stations now.  if the weather stations are anywhere near as high quality as their sensors, that should be a very nice weather station indeed!

decagon sensors use SDI-12

loggers have a USB and cell network interfaces for uploading data

http://www.decagon.com/en/

Offline Ann_Brush

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I bet it is Decagon or at least their anemometer, those parts look identical. Perhaps they teamed up with someone else for the temp / rain / solar / barometer sensors. Further some of Metergroup soil compactness instrumentation devices looks identical to some of that pictured by Decagon. The TAHMO weather network uses direct cell connections for data transfer, that would also tie in with what mwall says re cell network interfaces.

Offline CW2274

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I don't think its close to a Netatmo at all. Its not in the same league re accuracy specs (which are pretty decent) and it certainly isn't price wise. US pricing for ATMOS-41 (I emailed the company) is USD 1600.00 (March 2017) for the station alone.
$1600?? Yes, the spec are good, but there's a reason why proper weather stations aren't bundle up into one little device. As I stated before, looks to me like the sun is it's worst nightmare. I certainly wouldn't buy it; the best sensors in the world are useless without a proper sitting place.

Offline EnvBioPhys

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@CW2274, your comments about problems associated with an air temperature measurement exposed to solar radiation are certainly valid.  This would normally be a big problem.  Fortunately, we (METER, formerly Decagon and UMS) have good scientists on staff that are aware of these issues.  The ATMOS 41 has a pyranometer to measure solar radiation and an anemometer to measure wind speed, both of which are primary factors that control solar heating of the temperature sensor.  By doing a simple energy balance calculation, we were able to develop an algorithm to correct the air temperature measurement. 

We validated the correction against a high-end Apogee TS-11 aspirated radiation shield and found a 95% confidence interval of +/- 0.42 °C in the corrected ATMOS 41 air temperature measurement under all sky conditions.  To provide some frame of reference, we included an air temperature measurement made in a typical non-aspirated radiation shield (Davis Instruments) and found a 95% confidence interval of +/- 0.66 °C.  These results give us a lot of confidence that the ATMOS 41 air temperature measurements are actually more accurate than those made in a typical non-aspirated radiation shield.  The experiment and results have been presented at the American Society of Agronomy and American Geophysical Union meetings, and will be presented at the European Geosciences Union meeting next month.  We would be happy to send you the presentation if you’re interested.

Offline CW2274

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Thank you for the reply. The technology is very interesting. Had a little explanation of said technology been made available in the literature, my comments would have been different. With that said, temperature/humidity, precipitation collection, and wind data are all meant to be measured at specific separate locations, not together.
I look forward to see your device work in real world conditions.

Offline Scalphunter

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wonder how good it is at 50 and 60 below zero.


 and  in ice and blowing snow conditions

Offline EnvBioPhys

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The ATMOS 41 will not perform well under those conditions.  It is not heated, so I would expect ice and snow accumulation in the rain gauge funnel, in the ultrasonic anemometer flight path, and possibly on the pyranometer.  The air temperature sensor is also not well calibrated below -40 C, so there would be errors in that parameter at temperatures that low. 

Offline AMSFC

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Re: Metergroup ATMOS-41 Weather Station - anyone know anything about these.
« Reply #10 on: August 15, 2018, 04:18:08 AM »
I would hardly consider an Apogee TS-11 or a Davis as a reference instrument ... but of course, I understand that your scientists are much smarter than the hobbyist from Rotronic, E+E and everybody else by that matter.

Even being a forum for enthusiasts, there is no justification for spreading ignorance !!! Quite the opposite, you should do a job to educate and raise awareness.

@CW2274, your comments about problems associated with an air temperature measurement exposed to solar radiation are certainly valid.  This would normally be a big problem.  Fortunately, we (METER, formerly Decagon and UMS) have good scientists on staff that are aware of these issues.  The ATMOS 41 has a pyranometer to measure solar radiation and an anemometer to measure wind speed, both of which are primary factors that control solar heating of the temperature sensor.  By doing a simple energy balance calculation, we were able to develop an algorithm to correct the air temperature measurement. 

We validated the correction against a high-end Apogee TS-11 aspirated radiation shield and found a 95% confidence interval of +/- 0.42 °C in the corrected ATMOS 41 air temperature measurement under all sky conditions.  To provide some frame of reference, we included an air temperature measurement made in a typical non-aspirated radiation shield (Davis Instruments) and found a 95% confidence interval of +/- 0.66 °C.  These results give us a lot of confidence that the ATMOS 41 air temperature measurements are actually more accurate than those made in a typical non-aspirated radiation shield.  The experiment and results have been presented at the American Society of Agronomy and American Geophysical Union meetings, and will be presented at the European Geosciences Union meeting next month.  We would be happy to send you the presentation if you’re interested.

Offline EnvBioPhys

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Re: Metergroup ATMOS-41 Weather Station - anyone know anything about these.
« Reply #11 on: August 15, 2018, 12:13:29 PM »
@AMSFC, I am sorry if my response was somehow offensive to you.  I certainly was not implying anything negative about Rotronic or E+E (I'm actually not sure how you arrived at that conclusion), nor was I attempting to spread ignorance.  Maybe the problem is that I accidentally called out the wrong radiation shield from Apogee.  The actual unit we used is the TS-110 (https://www.apogeeinstruments.com/ts-110-ss-aspirated-radiation-shield-thermistor-included/), and not the TS-11 as was stated originally.  I do consider this to be a reference air temperature measurement.  However, if you have compelling evidence that there is a better alternative, I would be happy to hear about it.  Certainly, the non-aspirated Davis shield is not a reference measurement.  It was included in the trial for comparison only. 

Offline AMSFC

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Re: Metergroup ATMOS-41 Weather Station - anyone know anything about these.
« Reply #12 on: August 16, 2018, 04:49:44 AM »
@EnvBioPhys

What I find hard to understand is this part of your comment:

Fortunately, we (METER, formerly Decagon and UMS) have good scientists on staff that are aware of these issues.  The ATMOS 41 has a pyranometer to measure solar radiation and an anemometer to measure wind speed, both of which are primary factors that control solar heating of the temperature sensor.

...  which implies that well known companies like the ones mentioned (market references, among others), have been doing all wrong.

On the other hand, you have a low-cost Pyranometer w/ 5% accuracy + a Low Cost Ultrasonic Anemometer w/ 3% accuracy (roughly +/- 8% uncertainty already) ... then you use those values in a "simple energy balance calculation". My deep apology but Energy Balance is not simple at all. Let's forget that for now.

Is your Energy Balance affected by the sun angle of incidence (Direct, Diffuse and Reflected Radiation)?
Do you consider the position of the sun throughout the day?
Do you have GPS built-in to calculate the position of the sun throughout the day?

Just those basic details, will add at least another 5%-10% uncertainty to your "Energy Balance" equation (18% uncertainty and counting).
I could add the decay of humidity sensor (+/- 3%), pressure uncertainty changing everything in pV=nRT (directly affecting dew point and everything else by the way) ...

Bottom line ... it's physically impossible for you to offer "Accuracy ±0.6 °C", I would optimistically estimate ± 2 to 3 °C, which is fine for some applications but totally inadequate for others (e.g Agriculture).

Your response is not offensive just to me, it is offensive to anyone that knows a little bit of physics or to anyone closely interested in weather measurement.

The main purpose of measuring climate is to understand its evolution and to predict phenomena that can directly affect our safety, our economy ... at the end of the day, our ability to keep the planet healthy for future generations.
± 1 °C variation can destroy a crop, melt an Iceberg or raise the sea level 1 cm.

If you don't see it, it doesn't exist. Spreading ignorance doesn't help.
That's why global warming are FAKE NEWS (if you know what i mean).

Have a good day
« Last Edit: August 16, 2018, 05:12:44 AM by AMSFC »

Offline EnvBioPhys

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Re: Metergroup ATMOS-41 Weather Station - anyone know anything about these.
« Reply #13 on: August 16, 2018, 10:39:51 AM »
Clearly you will not be convinced by further discussion here.  When the peer-reviewed evaluation papers from independent research groups finish working their way through the publication process, I will try to remember to post links here for you.