Topic: Barani MS Pro vs SmartCellino radiation shield comparison

[Jasper3012]

I’ve been having “useless” conditions (from a comparison standpoint) for days now… Constantly either wind or cloud and sometimes both, with some rain aswell. Such conditions do not stress the shields and therefore the result is identical values.

[Dvalente75]

Me too same problem! I will post when there are interesting conditions!

[mauro63]

Keep an eye anyway on your data, these conditions, although they tend to level the performance, given the absence of radiative errors, can however highlight other types of errors, such as apparent underestimations in the case of intense precipitation.

An overcooling, linked to a possible wet-bulb effect can occur in these situations, usually can happen on the same on passive or ventilated solar radiation shields.

Usually the time needed for a an reallignement is very high on a passive shield, more quickly on a ventilated screen.

M.

[Jasper3012]

I don’t usually get any particularly heavy precip so I can’t say much on that either. Next week is looking calmer with sun and clear nights, at least for a while, so there should be some interesting data to come.

[ypsinine]

I am one of those interested in the data even if it's not a clear sky.

[Dvalente75]

My report of 15 October

[Jasper3012]

I am one of those interested in the data even if it's not a clear sky.

You can follow the data with the link I provided earlier in the thread.

[tobyportugal]

Report of yesterday

If you compare it with other days, it's clear that the difference is not due to the sun's rise.

[Kallo78]

Report of yesterday

If you compare it with other days, it's clear that the difference is not due to the sun's rise.

In this case i agree with you


Inviato dal mio SM-S921B utilizzando Tapatalk

[Kallo78]

Yesterday’s report and three-shield chart

[ypsinine]

You can follow the data with the link I provided earlier in the thread.

Thanks Jasper you are of course right. My comment was more directed to the other people posting summaries in this thread.

[mauro63]

You can follow the data with the link I provided earlier in the thread.

Thanks Jasper you are of course right. My comment was more directed to the other people posting summaries in this thread.

You're right, sorry, some problems at job, I have a bar and pizzeria, some times Is hard to find the time
I Will do
M.

[Jasper3012]

My report of 15 October

We can clearly see why passives cannot be compared to mechanically ventilated ones without different probes or without different smoothing in powerful ventilated ones. Otherwise we will collect differences unrelated to a bias of the shelters concerned. On the contrary, we will mask biases of the passives, because the ventilated ones will capture peaks and troughs that the passives will never see, because they smooth mechanically too much, especially in very dry regions with strong radiation and a small enough wind.....after as usual it remains a personal and unpretentious opinion

Yes and no. You can definitely still compare them if you know the characteristics of the shields well. For one, during sunny weather with an erratic temp for example, the active shield will likely have a higher amplitude for any given 10 min period, but the mean temp should still be similar. So in theory, for every given 10 min interval, the max should be higher, mean similar and the min lower on the active shield. When I was doing my testing with the Davis the Barani, I did in fact measure a higher amplitude on the Davis usually (indicating a better responsiveness), but at the same, the mean temp would often be multiple tenths higher, which indicates a radiation error. From this, I concluded that the Davis is in fact more responsive, but at the same time it suffers from a slight error during sun and wind. It’s obviously easier to compare like for like but you can still draw conclusions from an active vs passive comparison.

[Meteorology fan]

Davis FARS24H is simply a better shield than Meteoshield Pro III, as we will even provide a constant power supply. There is certainly less measurement uncertainty in many weather scenarios than in Barani.

Overall, I would choose Smart Cellino and Davis FARS24H.

[Jasper3012]

Davis FARS24H is simply a better shield than Meteoshield Pro III, as we will even provide a constant power supply. There is certainly less measurement uncertainty in many weather scenarios than in Barani.

Overall, I would choose Smart Cellino and Davis FARS24H.

The Barani gives better results in Belgium than the Davis. I feel quite strongly in saying that the Barani is a better choice in countries like the Netherlands, UK, Norway, western Canada and other locations with a highly maritime climate. For more continental locations and particularly those with cold and snowy winters, the Davis is likely the better option, if you can fix the power supply issue in winter.

[Meteorology fan]

And so I am in favor of comparing a passive shelter with an active one, although the fan in the Davis FARS24H could be more efficient, and that would require modifications. Something along the lines of the Apogee TS100, the insulation inside the shelter could be along the lines of the TS100, where we have walls filled with foam so that heat from the outside doesn't penetrate.

[Dvalente75]

18/10/24 Comments on the report are welcome

[Kallo78]

Short analysis MetPro 3 and Siap since installation Italian's shield

[mauro63]

I have to compliment all the participants in this and other posts, the quality of the contributions is evident, the technical competence of each one is evident, the experience, certainly gained in the field over the years, I appreciate less certain polemical contributions that hide purposes that I do not even want to know

It makes me smile, forgive me, because such experience does not take into account a fundamental aspect, that I have always tried to inject into this type of discussion but that seems to be deliberately ignored, we do not know the measurand!

An old modest writing of mine comes to mind, moreover subject to peer-review by an official institute, in which some references are made on the matter

I know that it has no value, and that it will be mocked and contested in every word, but I hope that, for someone, it can turn on a light 

 [ You are not allowed to view attachments ]

M.

[Jasper3012]

18/10/24 Comments on the report are welcome

I think we may not be seeing enough of the possible benefits of daytime ventilation in the mechanically ventilated Barani, as ventilation probably reduces the effective time constant of the shelter+probe assembly, compared with the fanless Barani and other passive shelters.

we'd have to check whether this is the case by comparing instantaneous T graphs with a probe that's not too slow, on a fine scale.

If the ventilated Barani displays more diurnal negative troughs, which will be more frequent and deeper than in the passive (because a passive that's not as good as a ventilated one will mainly display positive peaks skewed by solar radiation, compared with a ventilated one, which will display more negative troughs). I'm talking about instantaneous T or average instantaneous T/1mn/ 5 to 10s, if sensor constant < 50 s/ 1m/s ) With solar radiation and low wind levels, especially in summer (on very dry ground, we'll see even more), this means that the ventilated Barani is probably more efficient than the figures show, and that we need to study the differences in the effective constants of the 2 sets, to recalibrate the results, or use a slightly slower sensor in the ventilated set to show the reality of its performance compared with the passive Barani. (At night, it's the other way round: in the case of permanent ventilated shelters, only the positive peaks at night should be analyzed, since it's mainly the negative troughs when the wind dies down that contain the radiative bias of a passive, when the radiative conditions, even if relatively brief, are long enough for its time constant, whereas a good ventilated system is biased only slightly at night.)


it's useful to be well aware of the importance of natural and wind-driven convection in the actual rise in free-air T every second, especially in summer when the ground is very dry, and even more so as we move towards the equator, since the transfer of energy from the ground surface (whose T is the highest for air T measured at 2 m) to the air is the most important outside of the change of state, with natural convection and, even more so, wind-driven convection. This is essential if we are to get a good idea of what's going on in a heavily ventilated shelter, especially with a fast probe.
Whereas a passive shelter initially sees its T rise without wind, due to strong radiative effects, despite the long time constant in calm winds, when the wind picks up, convection provides energy in addition to the radiative bias.
The quality ventilated shelter is much more like air; it needs convection above all, and turbulence, to see the T rise quickly and very high, but briefly, with the very rapid changes in air T in dry, very hot weather and soil.

Passive shelters don't pick up on rapid variations if the wind varies too much, or if a small convective bubble rises just below, because they smooth it out too much. Real variations are smoothed out or contaminated by radiative bias (which is why passive shelters fail to see the numerous negative diurnal troughs captured by ventilated shelters).

There's definitely more analysis required when comparing active vs passive, compared to passive vs passive. I found this out when I was comparing the Davis vs the Barani. Typically, the data of 10 min averages gives a good idea of radiation errors, as it smooths out the higher peaks and lower troughs observed in the active shield. It's definitely a better method to compare the shields than just to look at the maxes, as like you said, one might mistake a higher tmax in the active shield as a radiation error, when it might just be a better representation of reality.

Thankfully, with this Barani vs SC comparison, time constants shouldn't play as big of a role, since we're comparing 2 passives and with identical sensors.

[Meteorology fan]

@Jasper3012 - You would see what happens with the Apogee TS100. There, the t-max is often higher than on the Davis FARS24H. The magic happens when the wind fades and quiets and then such aspirational creations show their claws.

A colleague who worked at WMO stations for several years explained this effect to us and showed us the evidence. Apogee TS100 images every change hence peaks are higher, does not flatten the measurement like passive radiation shields/cages. Sensitivity and response also better than Davis FARS24H.
Actually maybe averaging makes sense from 1 minute and 10 minutes. However, look at wind meters. You can average the value up to 3s, but isn't it better to image the peaks for a full picture of the full speed, which is supposedly against WMO recommendations. Admittedly, others will be on mechanical wind gauges and others on Vaisala WMT700-type ultrasound.

The Davis FARS24H is a nice complement to the Apogee TS100 and other passive shields

[Jasper3012]

@Jasper3012 - You would see what happens with the Apogee TS100. There, the t-max is often higher than on the Davis FARS24H. The magic happens when the wind fades and quiets and then such aspirational creations show their claws.

It would be interesting to compare average hourly temps and the hourly max between the Apogee and the Davis on a windy and sunny afternoon in summer. If the Apogee does not suffer from slight errors during such conditions like the Davis does, it should have a lower average hourly temp but it might still have an identical or even higher hourly max than the Davis, due to the even faster airflow.

[Jasper3012]

Thought I'd throw in this chart, showing the temp in the Barani minus the temp in the SmartCellino (SC) over the last 10 days. Not much difference, as you can see. I've not had any conditions that the Barani typically struggles with, so this result so far is expected and confirms the SC does very well in the conditions that the Barani typically handles very well. There will be some temporary high pressure next week so I'm hopeful for a calm and sunny morning and/or evening.

 [ You are not allowed to view attachments ]

[Meteorology fan]

This is what I plan to do in the near future, but due to my illness I only have Apogee mounted in the garden, but without power plugged in and only the sensors inserted. When I recover I plan to get the TS100 fully operational. I am still looking for a fairly small glass package for the voltage regulator what I will have at home.
The recording from the PT1000 sensor will be every 1 minute to make the data repeatable between Davis FARS24H, Barani Meteoshield Pro III. All synchronized to 1s based on Windows 10 time in Logsoft.

SHT35 without a filter will only give us a control comparison and interval on the graph every 5 minutes (it will average our measurement from 5 minutes) ideally it would be from 10 minutes or 1 minute. I like to be able to see online or check Termio for deviations in shielding. PT1000 to read the current values on the mast I have to connect to a computer to read the measured physical quantities and rip remotely from loggers with PT1000 sensors and there I can adjust the recording time and potential averaging to my liking in the program.

https://termoprodukt.co.uk/soft

https://termio.eu/

https://termio.eu/termoprodukt-lab

[Kallo78]

Report of yesterday. Rainy day and always cloudy apart during a short break from the precipitation. Deviations between instrument tolerance
Good Sunday to all