Author Topic: SRS100 radiation shield (Ambient Weather)  (Read 8402 times)

0 Members and 1 Guest are viewing this topic.

Offline METARMan

  • Senior Member
  • **
  • Posts: 59
SRS100 radiation shield (Ambient Weather)
« on: June 12, 2009, 07:30:15 PM »
Does anyone have any experience with the SRS100 (passive) radiation shield from Ambient Weather? 

http://www.ambientweather.com/amwesrpatera.html

Does the shield have a warm bias on high solar radiation days? 

I'm wondering whether I should build a cotton region shelter/Stevenson screen instead.

Online DanS

  • Chiang Mai weather
  • Forecaster
  • *****
  • Posts: 4949
    • ThaiWx
Re: SRS100 radiation shield (Ambient Weather)
« Reply #1 on: June 12, 2009, 07:37:22 PM »
If your sensor(s) placement will be exposed to any direct sunlight I'd recommend either going aspirated with that shield or the aspirated stevenson as you mentioned. If your sensor(s) are shaded all the time then the mentioned SRS100 should be fine. A fan is needed to keep the ambient air flowing to cool the heated enclosure from the direct sun's effect. Shaded locations don't have this condition and the shielded enclosure is used to protect the sensors from indirect solar radiation. Hope this helps.
Dan
« Last Edit: June 12, 2009, 07:48:39 PM by DanS »

Offline Downlinerz2

  • Forecaster
  • *****
  • Posts: 2929
Re: SRS100 radiation shield (Ambient Weather)
« Reply #2 on: June 12, 2009, 08:31:27 PM »
    I obtained the Radiation Shield from Ambient for my WMR968 sensor.  In direct sunlight, where it was exposed to the Sun for more than 2 hrs, I still experienced
an elevated temperature reading.  I would agree with Dan that if your sensor will be in direct sunlight you should go with the aspirated shield or the aspirated Stenvenson.   Good luck,
                  Mark

Offline wxtech

  • Weather Equipment Technician
  • Forecaster
  • *****
  • Posts: 1617
  • USAF Weather Equipment Maintenance Tech (retired)
    • Lexington, Ga. Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #3 on: June 12, 2009, 08:34:57 PM »
I have the SRS100LX which is just an extended version of the SRS100.  It adds more baffle plates and longer screws.
I use it to experiment with temperature sensors.  I measured daytime air flow vs nighttime air flow inside the shield.  I used a hot wire anemometer to compare the day/night air flow.  The day time air flow was measurably greater than night air flow inside the radiation shield.  It has .6" separation between plates for air intake at the narrowest point.
The solar shield was mounted in direct sunlight.
I have used it to compare 1-wire digital temperature sensors with analog RTD temperature sensors.  I never intended to make the shield fan aspirated.
In changing a sensors on a warm sunny day, the sensor was exposed to direct sun and partial shade for a few minutes.  During that time, the measured temperature went from about 70 to 75.  As soon as the sensor was replaced inside the shield, the measured temperature went back to 70.
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, XP with serial port, VWS v15.00 p02. ImageSalsa, Win8 all-in-one.
Selling used professional rain gauges on wx site

Offline sam2004gp

  • Mount Crawford, Virginia
  • Forecaster
  • *****
  • Posts: 2814
  • Weeeeeeeee!!!!
    • Mount Crawford Weather, VA
Re: SRS100 radiation shield (Ambient Weather)
« Reply #4 on: June 13, 2009, 07:44:44 AM »
I also have one, and I do experience some "sun heating" in the morning.  Therefore I put my temp/shield setup on the shady side of my vinyl fencing and it helped it some.  But during the summer months the angle of the sun still gets it in the morning.  I was looking at one time of constructing a modification to make it a solar FARS setup.  I still need to do that.  But I believe that would solve the problem you are concerned about.

I have some pics of the setup on my website, just scroll down on the left to the "Weather and Station Photos".
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


Offline METARMan

  • Senior Member
  • **
  • Posts: 59
Re: SRS100 radiation shield (Ambient Weather)
« Reply #5 on: June 13, 2009, 10:40:55 AM »
It is interesting that so much emphasis has been placed on accurate instrumentation, yet the variations in radiation shields and thermometer shelters probably have more to do with representative temperature data than the accuracy of the instruments themselves.  Although there are standards for thermometer instrumentation, there is no national or global standard for radiation shields/thermometer shelters (yet).

Even the standard cotton region shelters seem to give higher temperatures on sunny days (especially with snow cover) and lower temperatures at night compared to MMTS shelters.

Theoretically, even if instrumentation is extremely accurate and kept in the same place for decades, a change in shelter design or even a repaint can have an effect on temperature readings.

http://ams.confex.com/ams/pdfpapers/91613.pdf


Offline d_l

  • Forecaster
  • *****
  • Posts: 1654
  • Slide Mtn - Mt Rose
    • Thomas Creek Estates Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #6 on: June 13, 2009, 12:22:34 PM »
That is a very interesting paper.  I think the question of a warm bias on sunny days for that radiation shield (or any shield) depends on the amount of wind you can expect in your location. 

I've been comparing temperature readings from several nearby non-FARS VP2 ISSes to my 24 hr FARS ISS over the past six months to a year.  I found during sunny mornings the non FARS units definitely heat up faster than mine.  The morning heat up may extend into noon-early afternoon during the winter month's low sun angles.  Once the sun is more directly overhead, the temperature differences tend to equalize so either the ISS radiation sheltering effect is better from the top than on the sides or the winds pick up here more later in the day.  Probably the latter is the most important factor.  On sunny, windy afternoons the non-FARS ISS that is mounted the closest to mine in height, will generally track right with my temperatures.

I find that there is much more of a difference in nighttime cooling temps than in daytime heating bias.  On clear, windless nights (most nights here are like this), my temperatures are much cooler than the other two stations (3-10 degrees F). Partly this is due to their mounting heights AGL, one is mounted ~17-20 ft higher and the other maybe 4-6 ft higher than mine.  The higher the ISS the warmer it is at night (and cooler during the day).  However, I also think the nighttime temps drop so fast here due to radiation losses, that the fanless shields simply can't equilibate to the air temps as fast as mine.
--Dave--

Wireless VP2 w/ solar, 24hr FARS, Heater, (Envoy-WLIP)*2-Meteohub, plus custom VP2 @ 26', WL 6.0.0, WU & W4U=KNVRENO37 NetcamXL

People always talk about the weather, but they never do anything about it.  Not me.  I'm gonna measure it.  www.tceweather.com

Offline wxtech

  • Weather Equipment Technician
  • Forecaster
  • *****
  • Posts: 1617
  • USAF Weather Equipment Maintenance Tech (retired)
    • Lexington, Ga. Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #7 on: June 13, 2009, 12:36:26 PM »
Does anybody have a Davis ISS (or other brand) mounted inside a cotton region shelter?
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, XP with serial port, VWS v15.00 p02. ImageSalsa, Win8 all-in-one.
Selling used professional rain gauges on wx site

Offline SlowModem

  • Weather at the speed of dialup!
  • Forecaster
  • *****
  • Posts: 5909
  • WX @ 26.4 kbs
    • Watts Bar Weather - Ten Mile, TN
Re: SRS100 radiation shield (Ambient Weather)
« Reply #8 on: June 13, 2009, 01:53:25 PM »
It is interesting that so much emphasis has been placed on accurate instrumentation, yet the variations in radiation shields and thermometer shelters probably have more to do with representative temperature data than the accuracy of the instruments themselves.

I'm surprised that someone doesn't make a FARS model of the SRS100.  Seems like it would be a great seller.

Greg Whitehead
Ten Mile, TN

http://www.wattsbarweather.net


Offline wxtech

  • Weather Equipment Technician
  • Forecaster
  • *****
  • Posts: 1617
  • USAF Weather Equipment Maintenance Tech (retired)
    • Lexington, Ga. Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #9 on: June 13, 2009, 01:55:32 PM »
I'll build you one.  Want it 24 hours fan aspirated, solar powered?
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, XP with serial port, VWS v15.00 p02. ImageSalsa, Win8 all-in-one.
Selling used professional rain gauges on wx site

Offline SlowModem

  • Weather at the speed of dialup!
  • Forecaster
  • *****
  • Posts: 5909
  • WX @ 26.4 kbs
    • Watts Bar Weather - Ten Mile, TN
Re: SRS100 radiation shield (Ambient Weather)
« Reply #10 on: June 13, 2009, 02:04:12 PM »
I'll build you one.  Want it 24 hours fan aspirated, solar powered?

One of these days I'll probably get around to getting a high-classed setup, but I have higher priorities right now.  I was just thinking about the free market economy, filling a need and making a buck, etc.  I guess that's why I'm not a businessman.
Greg Whitehead
Ten Mile, TN

http://www.wattsbarweather.net


Offline wxtech

  • Weather Equipment Technician
  • Forecaster
  • *****
  • Posts: 1617
  • USAF Weather Equipment Maintenance Tech (retired)
    • Lexington, Ga. Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #11 on: June 13, 2009, 02:10:45 PM »
I'll build you one.  Want it 24 hours fan aspirated, solar powered?

One of these days I'll probably get around to getting a high-classed setup, but I have higher priorities right now.  I was just thinking about the free market economy, filling a need and making a buck, etc.  I guess that's why I'm not a businessman.
I have the set-up.  Problem is I don't have the motivation. 

You could buy this kit of solar panel wire and fan and modify your SRS100.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G17171
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, XP with serial port, VWS v15.00 p02. ImageSalsa, Win8 all-in-one.
Selling used professional rain gauges on wx site

Offline SoMDWx

  • Forecaster
  • *****
  • Posts: 640
    • Southern Maryland Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #12 on: June 13, 2009, 02:30:21 PM »
I have an SRS100 with no fan and it seems to keep temps just fine. No different than when I had a FARS in place....


Jim
Jim Wyman
Certificate In Weather Forecasting Graduate, Fall '11, PSU
Creator of Scit Pro
Southern Maryland Weather
http://somdweather.com
http://scit.somdweather.com

Offline mackbig

  • Forecaster
  • *****
  • Posts: 4121
    • Mackie's Main Street, Unionville, ON Canada Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #13 on: June 13, 2009, 02:38:13 PM »
Jim,
When/why did you remove your FARS?

I was just going to install mine today/tomorrow.  I still have to run some wire out to it, dont want to run my lights 24's a day light in winter for my rain gauge heater.

Andrew

I have an SRS100 with no fan and it seems to keep temps just fine. No different than when I had a FARS in place....


Jim

Andrew - Davis VP2+ 6163, serial weatherlink, wireless anemometer, running Weather Display.  Boltek PCI Stormtracker, Astrogenic Nexstorm, Strikestar - UNI, CWOP CW8618, GrLevel3, (Station 2 OS WMR968, VWS 13.01p09), Windows 7-64

Offline SoMDWx

  • Forecaster
  • *****
  • Posts: 640
    • Southern Maryland Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #14 on: June 13, 2009, 04:48:23 PM »
Well it's like this:

My homemade FARS unit was had chipping paint and the fan was getting really gunk up. I saw the SRS100 on the ambient site and thought I'd give it a whirl..
The sensors fit right in there and it is easy to assemble. The unit is already molded in white so no pealing paint there. As I stated before, I am seeing very little/no difference in my readings in direct sunlight. I do have 12V DC running to my unit which I could modify to use a fan. I just haven't done it yet and right now, the readings are telling me i don't need to..


jim
Jim Wyman
Certificate In Weather Forecasting Graduate, Fall '11, PSU
Creator of Scit Pro
Southern Maryland Weather
http://somdweather.com
http://scit.somdweather.com

Offline METARMan

  • Senior Member
  • **
  • Posts: 59
Re: SRS100 radiation shield (Ambient Weather)
« Reply #15 on: June 13, 2009, 05:37:10 PM »
This is the most comprehensive study I've come across regarding different radiation shields:

http://www.knmi.nl/klimatologie/onderzoeksgegevens/homogeen_260/meulenbrandsma2007b.pdf

Online DanS

  • Chiang Mai weather
  • Forecaster
  • *****
  • Posts: 4949
    • ThaiWx
Re: SRS100 radiation shield (Ambient Weather)
« Reply #16 on: June 13, 2009, 07:41:05 PM »
Well written article describing a thorough test. The "microclimate that develops within the screen" and "thermal inertia" sections describe why mechanical aspiration may be needed when exposed to direct sunlight.  I got it saved now and thank you for sharing.

Dan
« Last Edit: June 13, 2009, 08:20:02 PM by DanS »

Offline METARMan

  • Senior Member
  • **
  • Posts: 59
Re: SRS100 radiation shield (Ambient Weather)
« Reply #17 on: June 14, 2009, 06:57:07 PM »
While a microclimate (raised temperatures) may develop inside a radiation shield that isn't aspirated, these studies seem to indicate that night aspiration cause a microclimate of their own by not allowing the air to become stratified (calm) and keeping the temperature inside the shield slightly elevated.  So, perhaps daytime aspiration is best while at night fans should be off? 

Online DanS

  • Chiang Mai weather
  • Forecaster
  • *****
  • Posts: 4949
    • ThaiWx
Re: SRS100 radiation shield (Ambient Weather)
« Reply #18 on: June 14, 2009, 07:54:12 PM »
Good question. From what I've been seeing, any shield that is subjected to solar radiation will absorb heat build up to some degree (material, color, amount of exposure, etc). The mechanical aspiration helps to remove this heat build up and maintain the inside temperature close to the outside surrounding air temperature. Running the fan at night would only give slightly faster response times to outside air temperature changes (if no breeze or wind). I also gather from the studies that a shield that is not exposed to direct solar radiation will follow the surrounding ambient air temperature without needing mechanical aspiration as the shield material doesn't need cooling. This can be seen on cloudy/overcast days.
I removed the fan from my radiation shield and I'm staying under 2F degree difference with the airport 1/2 mile away. Still experimenting to tighten that spec. down though.

Dan
« Last Edit: June 14, 2009, 10:54:59 PM by DanS »

Offline JFHughes08088

  • Member
  • *
  • Posts: 4
    • Weather conditions in Tabernacle, NJ
Re: SRS100 radiation shield (Ambient Weather)
« Reply #19 on: August 01, 2009, 04:57:39 PM »
I just installed the Ambient Weather SRS 100 today.  Noticed an initial temp drop of 4-5 degrees immediately after install.  I'll keep track against local weather to compare. 

I have a slight concern since it is mounted on the side of the house (20 ft. up), which is aluminum siding, although the house is light blue so I don't think i'm getitng much radient heat from the house.  Anyone have any thoughts on this?
LaCrosse Technology WS 2310
Ambient Weather SRS100 Passive Radiation Shield

Offline floodcaster

  • Forecaster
  • *****
  • Posts: 391
    • Goose Lake Weather
Re: SRS100 radiation shield (Ambient Weather)
« Reply #20 on: August 01, 2009, 05:08:42 PM »
I just installed the Ambient Weather SRS 100 today.  Noticed an initial temp drop of 4-5 degrees immediately after install.  I'll keep track against local weather to compare. 

I have a slight concern since it is mounted on the side of the house (20 ft. up), which is aluminum siding, although the house is light blue so I don't think i'm getitng much radient heat from the house.  Anyone have any thoughts on this?

You'll likely run into problems. What direction is it facing? Can you relocate to above the grass?

Many years ago I temporarily setup my temp/RH sensor (Davis WMII) inside the non-aspirated radiation shield on my TV tower located about 4 feet above ground. The tower was only about 4 feet from my house and was facing east. My house has a tan vinyl siding. In the morning when the sun was warming the house, the reflected heat caused the temp to read about 5 to 10 degrees higher than surrounding stations. The temp dropped to normal when the sun was no longer heating the side of the house.
Bill


Offline JFHughes08088

  • Member
  • *
  • Posts: 4
    • Weather conditions in Tabernacle, NJ
Re: SRS100 radiation shield (Ambient Weather)
« Reply #21 on: August 01, 2009, 07:14:31 PM »
Thanks for the reply. It faces south east but since I live is a densely wooded area, it doesn't get much "direct" sunlight.  I'll watch to see if I get spikes in late moring temp, then a drop when it crosses over the top of the house.  If yes, I would still be getting solar heat readings.   My larger concern is radient heat from the aluminum siding.  I installed it on the top corner on the back side of a 2 story house.  
« Last Edit: August 01, 2009, 07:35:37 PM by JFHughes08088 »
LaCrosse Technology WS 2310
Ambient Weather SRS100 Passive Radiation Shield

Offline Likesspace

  • Member
  • *
  • Posts: 39
    • Middleton Street Station
Re: SRS100 radiation shield (Ambient Weather)
« Reply #22 on: August 12, 2009, 10:33:04 PM »
Hi guys,
First of all, I'm totally new to this hobby and I'm having a blast playing around.
My stations is a cheapo Zephyr/Watson/Fine Offset/ WH1081/Multi-branded model that sells for about $120.00 U.S..
My reason for posting is a recent discovery I've made with this station.
First off, this model does come with a radiation sheild although it's tiny compared to my dad's Davis VP2 (approx. 1-1/2" diameter).
Although this shield does block the direct sunlight, it also still shows up to 4 degrees F higher than other local stations that are mounted in the shade.
My station is mounted on a post setup approx. 5 foot above my garage roof. Early on I decided that my main problem was a lack of ventilation through the radiation sheild, but I really didn't know what to do about it.
After giving a lot of thought to building my own aspirated shield, I decided to play around with my mounting and came up with the following solution:
My Wind setup consists of a seperate directional sensor and speed sensor.
I moved the temp/humidity sensor to approx. 1", directly below the wind speed sensor, thinking that the movement from the speed sensor woudl provide some air flow across the temp sensor.
Well today I gave this setup it's first test and although it's not perfect, I was impressed with the results.
When the air movement was below 5 mph, I still got about a 1 - 2 degree F increase in temp readings above those of neighboring stations.
When the air movement was above 5 mph I was pretty much right on with my readings and anything over 6 mph air movement I was the same if not lower than my neighbor's readings.
I know that one day doesn't tell the story, but I did find these readings interesting.
If this continues to work out I might have found a solution that does not require an active solar radiation sheild.
I'll try to keep everyone updated with my results and I hope this helps someone out.

Dave
Zephyr PWS-1000TD with Fan Aspirated SR100 Radiation Shield

Software: Cumulus v 1.8.7

Offline SlowModem

  • Weather at the speed of dialup!
  • Forecaster
  • *****
  • Posts: 5909
  • WX @ 26.4 kbs
    • Watts Bar Weather - Ten Mile, TN
Re: SRS100 radiation shield (Ambient Weather)
« Reply #23 on: August 12, 2009, 10:38:08 PM »
Although this shield does block the direct sunlight, it also still shows up to 4 degrees F higher than other local stations that are mounted in the shade.
My station is mounted on a post setup approx. 5 foot above my garage roof.

That's probably a big part of your problem.  There's a lot of heat that may be coming off the roof.  If possible, I'd suggest putting the temp sensor closer to ground level.
Greg Whitehead
Ten Mile, TN

http://www.wattsbarweather.net


Offline sam2004gp

  • Mount Crawford, Virginia
  • Forecaster
  • *****
  • Posts: 2814
  • Weeeeeeeee!!!!
    • Mount Crawford Weather, VA
Re: SRS100 radiation shield (Ambient Weather)
« Reply #24 on: August 13, 2009, 07:02:17 AM »
Although this shield does block the direct sunlight, it also still shows up to 4 degrees F higher than other local stations that are mounted in the shade.
My station is mounted on a post setup approx. 5 foot above my garage roof.

That's probably a big part of your problem.  There's a lot of heat that may be coming off the roof.  If possible, I'd suggest putting the temp sensor closer to ground level.

x2, about 6 feet above a grass surface away from heat radiating sources like the siding of your house.
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


 

anything