Author Topic: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD  (Read 8587 times)

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Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #400 on: August 16, 2018, 11:52:46 PM »
Here is one to ponder everyone. The KVTN ASOS 1.3 mi distance, High was 87.1 today. That's still 2 warmer than the warmest shield (Standard).
So any of these shields looked stellar when comparing with the ASOS FARS  #-o
So the hard sucking FARS doesnt matter, geography really makes the big difference. I'm sure I have my own summer micro climate with all the vegetation.
 
Randy

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #401 on: August 17, 2018, 12:16:10 AM »
Here is one to ponder everyone. The KVTN ASOS 1.3 mi distance, High was 87.1 today. That's still 2 warmer than the warmest shield (Standard).
So any of these shields looked stellar when comparing with the ASOS FARS  #-o
So the hard sucking FARS doesnt matter, geography really makes the big difference. I'm sure I have my own summer micro climate with all the vegetation.
 

Looks like your other station (E7498), outside of town, hit 84 (still with the 7714?). So with more trees/turf around in town, 83 (FARS high) could be accurate. Either way, 83/84 seems entirely plausible to me. 

As for the airport, that's a head scratcher. Didn't you say that the local COOP observer has also been showing lower temps than the airport since the jump last year?
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Offline CW2274

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #402 on: August 17, 2018, 12:36:22 AM »
That's still 2 warmer than the warmest shield (Standard).
So any of these shields looked stellar when comparing with the ASOS FARS  #-o
Well, not if they were side by side. I mean, you yourself verified the ASOS temp was spot on accurate only 2 or 3 weeks ago, right?

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #403 on: August 17, 2018, 12:47:18 AM »
Thinking further about it... on a day with almost no wind heat can easily stagnate in one area. Tons of microclimates develop. The additional plant life in town could moderate and absorb some of the heat in places. Not sure you can read too much into the airport temp on such a day.
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Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #404 on: August 17, 2018, 08:07:55 AM »
It is a head scratcher and yes the other station similar to AP was also 84 with the 7714. Yes I did the airport test a week ago, high temp was right but low was +1.4 high,  so something still amiss I think . The Coop is in town so would have similar readings to what I have.
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #405 on: August 17, 2018, 09:11:44 AM »
Update I was asked if I would continue testing all shields for long term study.
So guess Ill set up the shields a little different instead of using tripod I need a permanent setup.
Another project and yes I enjoy stuff like this as you can imagine.


Heard back from Allmeteo and got refunded for standard. Sent them all my data in CVS form from test.
Also ordered a second Pro unit for remote site.

I do think the Pro is as good as any passive shield can get even surpassing the highly regarded 7714. 

Those that have a breeze like Jerry living on the Gulf will never miss the FARS. If you are in the desert I wouldn't change over however.

Randy

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #406 on: August 17, 2018, 09:26:58 AM »
Update I was asked if I would continue testing all shields for long term study.
So guess Ill set up the shields a little different instead of using tripod I need a permanent setup.
Another project and yes I enjoy stuff like this as you can imagine.


Heard back from Allmeteo and got refunded for standard. Sent them all my data in CVS form from test.
Also ordered a second Pro unit for remote site.

I do think the Pro is as good as any passive shield can get even surpassing the highly regarded 7714. 

Those that have a breeze like Jerry living on the Gulf will never miss the FARS. If you are in the desert I wouldn't change over however.
Tell them you'd be glad to, but you need one of their temp/hum probes free of charge too. ;)

It actually looks like they use the SHT75 based on the specs. +/- 1.8% RH is usually a dead giveaway.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #407 on: August 17, 2018, 10:45:17 AM »
Update I was asked if I would continue testing all shields for long term study.
So guess Ill set up the shields a little different instead of using tripod I need a permanent setup.
Another project and yes I enjoy stuff like this as you can imagine.


Heard back from Allmeteo and got refunded for standard. Sent them all my data in CVS form from test.
Also ordered a second Pro unit for remote site.

I do think the Pro is as good as any passive shield can get even surpassing the highly regarded 7714. 

Those that have a breeze like Jerry living on the Gulf will never miss the FARS. If you are in the desert I wouldn't change over however.
Tell them you'd be glad to, but you need one of their temp/hum probes free of charge too. ;)

It actually looks like they use the SHT75 based on the specs. +/- 1.8% RH is usually a dead giveaway.

They did say keep the standard and sending out free Pro for my trouble.  (not really trouble if you enjoy it)  Instead of slimming down I just spent $40 concreting 2 more poles in for better separation so committed now and have more stuff to mow around LOL
Randy

Offline Bobvelle

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #408 on: August 17, 2018, 11:42:39 AM »



 
Broke down FARS against each shield for cleaner comparision


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Great Info!
Are the temps at the top the Average or standard deviation or...?
It Looks like my standard Meteo is doing about as good as your Pro...I'm only getting 1.5 -2 deg difference in the sun too Hmm

Well, what's your wind like? Looks like Randy hit a max of 2mph the entire test period today! That's about as good as it gets for testing shields. If there were any errors to be found, they'd be sure to show up.

EDIT: missed that you posted 1.5mph avg wind. Randy didnt give an average but his appears to be lower just looking at his graph. That might explain the discrepancy.

His does "look" closer, but then again, his index lines are 5 deg apart.  :-)

I'm not making the claim that the standard is just as good as the Pro... I was just surprised that the standard did that well in my comparative test. After making things more equal between the FARS and the standard Meteo shield, I went back and compared the 14th graph (FARS mostly shaded) and the 16th graph (both getting equal exposure) and the difference narrowed by .5 deg. So there was some improvement.
Moreover, I'm pretty sure that if i shaded the Meteo Standard and the FARS during peak sun hours the numbers would be even closer given the same wind, or lack there of.
« Last Edit: August 17, 2018, 11:46:43 AM by Bobvelle »

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #409 on: August 17, 2018, 12:51:24 PM »
His does "look" closer, but then again, his index lines are 5 deg apart.  :-)

I'm not making the claim that the standard is just as good as the Pro... I was just surprised that the standard did that well in my comparative test.

I meant that his wind graph seems to indicate his average wind was lower than 1.5mph. If, indeed, your winds were higher that would explain why the standard shield did better in your tests.

Of course, you could argue you had higher solar insolation than him because of your more southerly latitude so that should cancel any slight wind advantage he had.

Scientific studies of any kind, even the informal ones being conducted in this thread, live and die on small details that may be imperceptible or difficult to quantify.

Sure, moving the shield to shade may help, but you'd also be measuring air less directly heated by the sun. On a calm day there could be a noticeable difference. IMO, a solar radiation shield that doesn't perform well in the sun is a bad solar radiation shield.
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Offline Bobvelle

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #410 on: August 17, 2018, 01:25:08 PM »
His does "look" closer, but then again, his index lines are 5 deg apart.  :-)

I'm not making the claim that the standard is just as good as the Pro... I was just surprised that the standard did that well in my comparative test.

 IMO, a solar radiation shield that doesn't perform well in the sun is a bad solar radiation shield.
Agreed. But the only thing I know of that would not allow ANY heat (radiation) from affecting the enclosed sensor in stagnate air environment would be a lead lined vacuum chamber. Heat is going to find its way in to affect the reading no matter how well it's made, if there is little to no wind. So does a "good" radiation shield even exist?
I honestly don't know..just asking the question.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #411 on: August 17, 2018, 01:36:07 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

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Randy

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #412 on: August 17, 2018, 01:39:01 PM »
I'm going to report a bit early today because we have some smoke moving in from Canadian wildfires soon. It's been clear all morning so far.

Just looking at the past 2 hours of data (11AM - 1PM EDT) the 7714 is dead even with the FARS in avg temp (0.08F diff). However, the FARS max temp in those 2 hours was 0.5F warmer than the 7714. Avg wind speed at 28ft was 3.33mph. I'd guess 3mph or less at 20ft (7714) and under 2mph at 5ft (FARS).

So.... my guess is the height differential plays in significantly here. The FARS is about 20 ft from a two lane residential paved road. It's about 30 ft from a 3 car width driveway (that's about 25 feet long). Perhaps being up and away from that radiation in a more mixed environment gives a truer picture of mesoscale conditions? Could also just be the old rule of higher is cooler (standard lapse rate under high pressure). Hard to say what is the ideal siting here. Although the agreement overall, especially at night, between the two shields is remarkable.

I can't easily move my FARS up to 20', but I suspect that if I did, though, the FARS would run even cooler than the 7714. Although the point for me isn't to find the coolest spot on the property. It's to find where a passive, backup shield best matches my active shield. I think I may have found the spot, but it's still early going. Need to see some clear nights and, ideally, some clear days with a blanket of fresh snow. That'll be awhile assuming the snow gods aren't in a perverse mood  ;).
« Last Edit: August 17, 2018, 05:09:37 PM by openvista »
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Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #413 on: August 17, 2018, 01:51:21 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

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Looks like Davis HQ. lol

In the pics of the shields I see on their site, it looks like the "gills" slope downward from the mounting bracket outward. Yours seem to be in the opposite direction, sloping upward. Is it possible to switch them around 180 degrees so that they're sloping downward toward the south side? Maybe it wouldn't make a difference...just an idea. I'm assuming your mounting arms are already aiming S based on the shadows in your pic.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #414 on: August 17, 2018, 02:07:40 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

 [ You are not allowed to view attachments ]
Looks like Davis HQ. lol

In the pics of the shields I see on their site, it looks like the "gills" slope downward from the mounting bracket outward. Yours seem to be in the opposite direction, sloping upward. Is it possible to switch them around 180 degrees so that they're sloping downward toward the south side? Maybe it wouldn't make a difference...just an idea. I'm assuming your mounting arms are already aiming S based on the shadows in your pic.
I'll take a look see if I figure out what you see.
Randy

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #415 on: August 17, 2018, 02:15:01 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

 [ You are not allowed to view attachments ]
Looks like Davis HQ. lol

In the pics of the shields I see on their site, it looks like the "gills" slope downward from the mounting bracket outward. Yours seem to be in the opposite direction, sloping upward. Is it possible to switch them around 180 degrees so that they're sloping downward toward the south side? Maybe it wouldn't make a difference...just an idea. I'm assuming your mounting arms are already aiming S based on the shadows in your pic.
I'll take a look see if I figure out what you see.
The gills slope downward from the mounting bracket side in these images.

https://www.allmeteo.com/meteo-shop/?category=Temperature

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #416 on: August 17, 2018, 02:36:24 PM »
His does "look" closer, but then again, his index lines are 5 deg apart.  :-)

I'm not making the claim that the standard is just as good as the Pro... I was just surprised that the standard did that well in my comparative test.

 IMO, a solar radiation shield that doesn't perform well in the sun is a bad solar radiation shield.
Agreed. But the only thing I know of that would not allow ANY heat (radiation) from affecting the enclosed sensor in stagnate air environment would be a lead lined vacuum chamber. Heat is going to find its way in to affect the reading no matter how well it's made, if there is little to no wind. So does a "good" radiation shield even exist?
I honestly don't know..just asking the question.

Very good question. The WMO study actually found that all selected shields measured warmer than a sonic anemometer they were using as a control (because they are immune to solar radiation). Unfortunately, they had to dump the anny data due to a technicality. That's why I found it curious that they said the FARS ran colder than the reference shield at times but then admitted that reality itself was significantly colder at all times!

Regardless, I think it all goes back to what can you live with. For each of us that's going to be different. For me, I just want a station that conforms to modern, accepted measurement standards and best practice to the extent that's possible in an urban neighborhood. Since almost no one uses sonic anemometers to measure temperature (because they are a bear to set up properly and keep calibrated for temperature measurement), the modern gold standard is an aspirated shield. Forecasts are based on such data.

I track forecast accuracy (https://marquetteweather.com/fx_accuracy.php) and over the past year, my temps average (net) about 1F warm for highs and lows up to 3 days out compared to the NWS point forecast. I'm within 3F about 70% of the time (same day forecasts). I'd say that's excellent given my location in a city lacking accurate model output statistics (the basis for climatology in weather models) and being mere blocks from poorly-modeled Lake Superior that LOVES to throw curve balls.
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Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #417 on: August 17, 2018, 02:50:19 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

 [ You are not allowed to view attachments ]
Looks like Davis HQ. lol

In the pics of the shields I see on their site, it looks like the "gills" slope downward from the mounting bracket outward. Yours seem to be in the opposite direction, sloping upward. Is it possible to switch them around 180 degrees so that they're sloping downward toward the south side? Maybe it wouldn't make a difference...just an idea. I'm assuming your mounting arms are already aiming S based on the shadows in your pic.
I'll take a look see if I figure out what you see.
The gills slope downward from the mounting bracket side in these images.

https://www.allmeteo.com/meteo-shop/?category=Temperature

Here is close-up. Does this still look different?
Shield came together all I did is mount sensor and bottom bracket.

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Randy

Offline havtrail

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #418 on: August 17, 2018, 03:00:29 PM »
Average wind speed was really low yesterday, highest I saw was .2 MPH and not much better today.
New setup image. Concrete is still drying, the standard shield needs straightened after it dries little more.

 [ You are not allowed to view attachments ]
Looks like Davis HQ. lol

In the pics of the shields I see on their site, it looks like the "gills" slope downward from the mounting bracket outward. Yours seem to be in the opposite direction, sloping upward. Is it possible to switch them around 180 degrees so that they're sloping downward toward the south side? Maybe it wouldn't make a difference...just an idea. I'm assuming your mounting arms are already aiming S based on the shadows in your pic.
I'll take a look see if I figure out what you see.
The gills slope downward from the mounting bracket side in these images.

https://www.allmeteo.com/meteo-shop/?category=Temperature

I think it's simply that one view is from the right side of the bracket and the other view is from the left side of the bracket.
Helixes will do that...

Rich K.
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Offline Bobvelle

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #419 on: August 17, 2018, 03:03:07 PM »
If you dismount the bracket, spin 180 and reattach, it will look identical to Allmeteo's photos.

Wish I had one  :sad:

Edit: Or maybe just spin it around like Rich K. says.
« Last Edit: August 17, 2018, 03:06:24 PM by Bobvelle »

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #420 on: August 17, 2018, 09:18:35 PM »
This is how most would mount for sensor cable to reach, so gave it a try. The 16" pizza pan is optional.  :-)

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Randy

Offline Bobvelle

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #421 on: August 17, 2018, 09:31:44 PM »
I like it!

Your neighbors must think your a nut though  :lol:

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #422 on: August 17, 2018, 09:40:43 PM »
Probably!
I picked the 16" pizza pan up at dollar general cheap. Its bolted on to the base of Davis mount so I drilled a hole in shield directly under the ISS for cable to reach.
I got almost done and realized the solar mount needed to go on first before the shield.  ](*,)  Anyway 2 more to go should go faster I have all the hardware now.  Im going to mount the standard same way so all are equal.
It actually cleaned the area up getting the solar cells above the shield and looks pretty good.

Oh! Almost forgot I used a rubber insulation on shield side of pizza pan. This is same stuff you line floor boards with & maybe hard to find. I already had a big roll and its super sticky once on it doesn't come off.
« Last Edit: August 17, 2018, 09:45:05 PM by ValentineWeather »
Randy

Offline Bobvelle

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #423 on: August 17, 2018, 09:49:00 PM »
I had trouble keeping my meteo bracket stable with just one U-bolt. Had to use 2, I guess your not having an issue with it?

So your still going to be testing the standard? Thought you were going to give up on it.

Offline CW2274

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #424 on: August 17, 2018, 10:07:57 PM »
I picked the 16" pizza pan up at dollar general cheap.
Pizza pan... :???: