Author Topic: Official weather measurements  (Read 2545 times)

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Offline drew1021

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Official weather measurements
« on: November 30, 2023, 03:13:49 PM »
Does anyone know what equipment is being used to measure various weather parameters at the official sites throughout Canada? Ive tried to research over the internet to no avail. I would think that whatever they are using would have to meet WMO standards.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline PaulMy

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Re: Official weather measurements
« Reply #1 on: November 30, 2023, 05:11:28 PM »
Hi,
I don't know but you could contact them through https://weather.gc.ca/mainmenu/contact_us_e.html
They recently replied to me when I asked about snow recording information and climate normals.
The email I have for them is ECWeather-Meteo@ec.gc.ca

Enjoy,
Paul

Offline drew1021

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Re: Official weather measurements
« Reply #2 on: November 30, 2023, 06:45:46 PM »
Thanks! Will contact them and reply back with their response.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline CW7491

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Re: Official weather measurements
« Reply #3 on: December 01, 2023, 10:07:02 PM »

Offline drew1021

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Re: Official weather measurements
« Reply #4 on: December 02, 2023, 09:16:51 AM »
Thanks, good info! This tells me that as of 2013 they were using the Stevenson screen with built in aspiration at some sites. I would suspect by now they would have gone to something similar to ASOS. Ive messaged them but havent heard back yet.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline CW7491

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Re: Official weather measurements
« Reply #5 on: December 02, 2023, 12:24:22 PM »
Let us know what you find out. I wouldnt be surprised if theyre still using an aspirated Stevenson screen as the UK still uses them.

Offline drew1021

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Re: Official weather measurements
« Reply #6 on: December 02, 2023, 12:51:01 PM »
IDK, Im all about standardization. Its kinda like comparing red delicious apples to Granny Smith apples. Both apples but very different taste.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline CW7491

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Re: Official weather measurements
« Reply #7 on: December 02, 2023, 03:14:45 PM »
Looks like as of 2018 they were still using them and studying the differences between the aspirated and non aspirated versions

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.5453

Offline drew1021

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Re: Official weather measurements
« Reply #8 on: December 02, 2023, 04:50:26 PM »
Interesting read. Seems to me that the Stevenson screen has advantages over the ASOS fan aspirated shield. If the fan fails in the ASOS shield theres no way to get any flow past the sensor resulting in large temperature difference, to the positive as I see it. If fan fails in Stevenson screen the difference would be minor due to the location of the temperature probe. Anyway thanks for the link. [tup]
« Last Edit: December 02, 2023, 04:52:16 PM by drew1021 »
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline CW7491

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Re: Official weather measurements
« Reply #9 on: December 03, 2023, 10:08:25 AM »
That point has been brought up by johnd and Prodata for folks in the UK based on their weather and latitude. They recommend the DFARS instead of the FARS version of the VP2 for the same rationale: if the fan quits for whatever reason, you will still have natural aspiration working for you giving you representative results.

Your post made me think of something I havent heard anyone try or at least discuss trying: the effectiveness of a mains powered fan in the Davis DFARS. With the higher powered fan, it would be interesting to see how that shield would perform under strong radiation with the advantage of natural aspiration during windy periods and in the event of power failure.

Offline drew1021

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Re: Official weather measurements
« Reply #10 on: December 03, 2023, 12:54:30 PM »
Probably wont happen due to the fact that the average consumer may not have access to AC where they site the ISS. Also DFARS shielding is more susceptible to reflective radiation. I do understand the need for a stronger fan though.
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline drew1021

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Re: Official weather measurements
« Reply #11 on: January 21, 2024, 10:56:03 AM »
Sorry for the delay in getting this out as I just recently received a response.



Good day,

We thank you for your inquiry on December 1st regarding the instruments used at our weather stations to measure temperature and dew point. We apologize for the delay in responding to your request.

In Canada, ECCC's Automatic Weather Stations (AWS) is the primary surface weather observing network. For temperature measurement these stations currently use the YSI 44212EC temperature probe, which has a temperature range of -50C to +50C (0.09C linearity) with an accuracy of +/- 0.1C.

For humidity measurements, our stations currently use the Vaisala HMP155 humidity probe. The measurement range of this sensor is 0 to 100% RH with the following accuracy specifications:
1% RH (at 15 to 25C, 0 to 90% RH)
1.7% RH (at 15 to 25C, 90 to 100% RH)
(1.4 + 0.032 reading) % RH (at -60 to -40C)
(1.2 + 0.012 reading) % RH (at -40 to -20C)
(1.0 + 0.008 reading) % RH (at -20 to +40C) (1.2 + 0.012 reading) % RH (at 40 to 60C)

At the majority of our sites, the temperature and humidity sensors are kept in a ventilated Stevenson screen and the sensors are installed at approximately 1.5 metres above ground level. In some remote locations where grid power is not available, the temperature and humidity probes are housed in unventilated Stevenson screens or unventilated Gill shields. Approximately 70% of our network of just under 600 stations have ventilated screens.

We hope this answers your inquiry. Do not hesitate to contact us if you have any other questions. The Meteorological Service of Canada (MSC) is a primary supplier of meteorological information in Canada, and is continuously monitoring and maintaining its observation networks to ensure Canadians have access to reliable weather and climate data.

Best regards,

Manita Essurredeen
MSC's National Inquiry Response Team (NIRT)
ISO 9001:2015
Environment and Climate Change Canada
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline CW7491

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Re: Official weather measurements
« Reply #12 on: January 21, 2024, 08:23:36 PM »
Thanks for sharing. Nice to see them give a comprehensive answer too.

 

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