Topic: Barani pro passive shield

[ValentineWeather]

I've seen enough with the new Pro shield so it's going in service as the main radiation shield. I'm doing one more test that has nothing to do with the Pro performance by raising the sensor height to 80" (inches) above the ground to avoid the sprinklers this summer. I want to do some overnight low-temperature comparisons against the 5' (foot) Fars to see if the 2 extra feet height make a large enough difference.
I'll probably move back down to 5' shield height after sprinklers are off next fall. 
 [ You are not allowed to view attachments ]

[Jasper3012]

That will be interesting to compare. I have a bit of a random question, do you remember how long it took them to get the MeteoShield Pro delivered to your house? I ordered mine 3 days ago and am wondering when I should be expecting it. I guess it varies per country (plus the corona crisis now) but maybe it can give me an idea.

[ValentineWeather]

Not sure when they actually shipped, I was a tester for the shield last year and was asked if I would test the latest design. Seems like it showed up about a week around 7 days later.
My testing from last year contributed to the design change reducing the snowfield light reflection.

[Jasper3012]

Thanks for that. Although in Belgium we don't get much snow at all so I'm afraid it won't benefit me too much.

[Dador]

Although in Belgium we don't get much snow at all so I'm afraid it won't benefit me too much.

I hope you do the shield comparison. I'm really waiting for the comparison between Barani Pro and Davis 7714. Maybe someone will do a test? 

[ValentineWeather]

Although in Belgium we don't get much snow at all so I'm afraid it won't benefit me too much.

I hope you do the shield comparison. I'm really waiting for the comparison between Barani Pro and Davis 7714. Maybe someone will do a test? 

I thought mauro63 was going to test it.  I do have a 7714 somewhere but its a modified version painted black interior to reduce reflection so not manufacture stock.   

[ValentineWeather]

Thanks for that. Although in Belgium we don't get much snow at all so I'm afraid it won't benefit me too much.

Well, the test above confirmed both low wind and snow performance. As far as the shield goes when the wind blows the Pro is always doing better vs FARS. I'll post today's performance so you can see what I'm talking about. Take into the fact the PRO is now at 80" vs 62"

[ValentineWeather]

Here is the full day sunny solar peaked at 840 Wm2
 [ You are not allowed to view attachments ]
 [ You are not allowed to view attachments ]

[Jasper3012]

MeteoShield has been running for 2 days now, it's installed at 1,5 m below and to the left of the Davis rain collector. I'm only able to compare it to the WS-2902, but here are the results for first two days:

Day 1 tmax
Pro 12.3°C
WS-2902 13.4°C

Day 2 tmin
Pro 3.0°C
WS-2902 2.6°C

Day 2 tmax
Pro 12.5°C
WS-2902 13.2°C


 [ You are not allowed to view attachments ]

[Jasper3012]

The daytime performance is, as expected, solid. Day 2 had slightly more wind than day 1, which explains the slightly smaller difference between the two shields. Both days were completely sunny.

The Pro is much more responsive at night than the Davis standard shield, but still lags 0.2-0.4°C behind the WS-2902. That's probably down to the fact the Davis T/H sensor is much larger and therefore takes more time to cool than the WS-2902 T/H sensor.

[Dador]

The Barani's cover is placed in such a way that a shadow falls on it from the Davis rain gauge in the afternoon. It's best to put the cover in full sun all the time.

I follow the page myself where the readings from Barani and Davis daytime are compared. The results are interesting. Often there are no differences in readings.

Barani Pro - http://www.mcmeteorimini.altervista.org/template/indexDesktop.php

Davis daytime - http://mcmeteo.altervista.org/template/indexDesktop.php

[Jasper3012]

Do you have a reason as to why it should be in full sun? The cable for the Davis T/H sensor is very short so I have limited options. I could place the shield next to the Davis rain gauge but then that'll will be blocking off airflow into the shield.

[Dador]

Do you have a reason as to why it should be in full sun?

WMO Standards:

Code: [Select]

In order to achieve representative results when comparing thermometer readings at different
places and at different times, a standardized exposure of the screen and, hence, of the
thermometer itself is also indispensable. For general meteorological work, the observed air
temperature should be representative of the free air conditions surrounding the station over as
large an area as possible, at a height of between 1.25 and 2 m above ground level. The height
above ground level is specified because large vertical temperature gradients may exist in the
lowest layers of the atmosphere. The best site for the measurements is, therefore, over level
ground, freely exposed to sunshine and wind and not shielded by, or close to, trees, buildings
and other obstructions. Sites on steep slopes or in hollows are subject to exceptional conditions
and should be avoided. In towns and cities, local peculiarities are expected to be more marked
than in rural districts. Temperature observations on the top of buildings are of doubtful
significance and use because of the variable vertical temperature gradient and the effect of the
building itself on the temperature distribution.
Source: Measurement of temperature - WMO Library

Personally, I try to follow these recommendations and place my sensors in the sunniest areas of the plot with free air flow.

[mauro63]

Do you have a reason as to why it should be in full sun?

WMO Standards:

Code: [Select]

In order to achieve representative results when comparing thermometer readings at different
places and at different times, a standardized exposure of the screen and, hence, of the
thermometer itself is also indispensable. For general meteorological work, the observed air
temperature should be representative of the free air conditions surrounding the station over as
large an area as possible, at a height of between 1.25 and 2 m above ground level. The height
above ground level is specified because large vertical temperature gradients may exist in the
lowest layers of the atmosphere. The best site for the measurements is, therefore, over level
ground, freely exposed to sunshine and wind and not shielded by, or close to, trees, buildings
and other obstructions. Sites on steep slopes or in hollows are subject to exceptional conditions
and should be avoided. In towns and cities, local peculiarities are expected to be more marked
than in rural districts. Temperature observations on the top of buildings are of doubtful
significance and use because of the variable vertical temperature gradient and the effect of the
building itself on the temperature distribution.
Source: Measurement of temperature - WMO Library

Personally, I try to follow these recommendations and place my sensors in the sunniest areas of the plot with free air flow.

I agree, In this case, no Davis Vantage pro, even if perfectly installed, complies with WMO regulations

 [ You are not allowed to view attachments ]

we have to distinguish the shade of a screen according to the different scenarios:
- if the screen is in the shade for short periods, provided that this shadow concerns only the screen, and not the ground below, this is irrelevant for the purposes of a meteorological survey
- if instead, we talked about a comparison of performances between different shields, also in this case shading is not a problem, provided that all the screens under test enjoy the same shading and at the same moments, therefore they are always in the same conditions

Mauro

[Jasper3012]

The ground below and the surrounding plot is in full sunshine, so it should be representative. The WS-2902 shield I'm comparing to is also largely shaded by the rain gauge above it, so both shields are under similar conditions.

[ValentineWeather]

Speaking of those WMO guidelines I moved the FARS to the backyard and run a steady +2F over the PRO shield in the open front yard.
I'll attach an image where it's mounted at 7'. The yard as you can see is rather large but the trees and fence cause a heat island of sorts. The front location is much more open even if by an asphalt road its the better location.
So having free airflow is very important when setting up a weather station.

 [ You are not allowed to view attachments ]

[Jasper3012]

That's why I placed it below the Davis rain gauge and not next to it, so the airflow isn't hampered. It seems a waste to buy the MeteoShield if I'm going to place it somewhere with restricted airflow.

[ValentineWeather]

Yes from what I've learned good airflow is the #1 objective for accurate temperatures. This is why its challenging to find a good location that meets all needs in residential neighborhoods.

[Jasper3012]

I wanted to make a new thread but figured I'll ask it in here; is there a notable difference in max/min temp between (dry) bare soil and grass? The Pro has been running between 0.0-0.5 milder than the WS-2902 at night but it's located above grass, while the WS-2902 above bare soil. The grass extends like 2 meters on 3 sides of the Pro, with bare soil surrounding it on 3 sides and grass on the other.

I assume under windy conditions there's not much of a difference since the air is mixed about, but could this be a factor under calm conditions with strong cooling/heating?

[Jasper3012]

 [ You are not allowed to view attachments ]

[mauro63]

Today results, good solar radiation and, in the second part of the day, with low wind speed

Mauro

 [ You are not allowed to view attachments ]  [ You are not allowed to view attachments ]

[Jasper3012]

Very good performance yet again. I must say I've been impressed by the MeteoShield Pro since it's been in use, definitely think it's the best passive shield out there. Another pic of my setup below.
 [ You are not allowed to view attachments ]

[annapurna88]

In a few days we will start a comparison between

  Davis 7714 passive

  Davis 7714 with powerful fan

  Barani meteohelix

Maybe with SHT30 sensirion sensor in the Davis and SHT35 in barani...

If we succeed, we will make the comparison equipping the davis 7714 with a SHT35 with probe.


Here the Davis 7714 that will use in passive mode and with fun

 [ You are not allowed to view attachments ]

[annapurna88]

I've seen enough with the new Pro shield so it's going in service as the main radiation shield. I'm doing one more test that has nothing to do with the Pro performance by raising the sensor height to 80" (inches) above the ground to avoid the sprinklers this summer. I want to do some overnight low-temperature comparisons against the 5' (foot) Fars to see if the 2 extra feet height make a large enough difference.
I'll probably move back down to 5' shield height after sprinklers are off next fall. 
 [ You are not allowed to view attachments ]

Yuor radiation shield is cover on the top?

[ValentineWeather]

I've seen enough with the new Pro shield so it's going in service as the main radiation shield. I'm doing one more test that has nothing to do with the Pro performance by raising the sensor height to 80" (inches) above the ground to avoid the sprinklers this summer. I want to do some overnight low-temperature comparisons against the 5' (foot) Fars to see if the 2 extra feet height make a large enough difference.
I'll probably move back down to 5' shield height after sprinklers are off next fall. 
 [ You are not allowed to view attachments ]

Yuor radiation shield is cover on the top?

Don't understand the question, sorry.
Glad to see the 7714 test. So how do you keep the fan from getting wet?