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Author Topic: Temperatures at Eureka, Nunavut, Canada  (Read 1633 times)

Niall Dollard

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Temperatures at Eureka, Nunavut, Canada
« on: June 29, 2020, 01:42:20 AM »
Copying this over from the Melting thread.

In the past few days, temperatures at Eureka have skyrocketed. As they have over much of the CAA.

Eureka looks like shattering some old records. My first thoughts, when Oren put up the chart from Ogimet was that Eureka looked way too high.


No need to doubt, the CAA has quite a few weather stations and you can view daily and even hourly temperatures online. Here's a map showing these weather stations and the max temps (C, not F) for June 26th. Sweltering indeed.

No doubt some very warm temperatures. But I was a bit taken back by the Eureka temperature shown which is very close to record June temperature.

Closer inspection on weatherobs website shows there are synops from 2 sites at Eureka.

71917 and 71613

At time of posting 71917 is showing 17 C (following a supposed record June max of 19.1 C) while 71613 is showing 8 C following a max of 12.3 C.

Big difference over a short distance.

Going especially by the Tmins I think the data from 71917 is totally wrong.
could be be an elevation difference?

The problem at Eureka is that there are two temperature stations. Let's call them Eureka Climate and Eureka Airport. They are located about 2 km apart.

Comparison between the two stations has shown a difference of over 8 C between the two with Eureka climate, the one nearest the inlet being the cooler of the two.

Friv raised the question is there an elevation difference ? Ogimet give both at 10m but this is not correct. There is a sign at the airport indicating the elevation there is 256 ft.

The questions then are :

1) Is there something inherently wrong with the data from the airport eg sensor malfunction and/or incorrect exposure ?

or

2) Is this a feature of the unique climate of this high Arctic inlet?


Hopefully Environment Canada will be able to shed some light on this. But 2) is an interesting proposition, what could be happening to allow such a big differential over a shot distance ? Some thoughts:

* There is no night period as this lattitude at this time of the year. The sun's elevation goes from 13 deg to 33 deg

* The inlet is still frozen solid.

* As mentioned already one station is circa 10m near the frozen inlet and the other circa 78m. There is little or no snow now in the immediate vicinity. It is just bare earth or rock.

* The wind direction over the past few days has been predominantly westerly.

* Humidity is a lot lower at the airport station (due to the higher dry bulb temps) but dew points are quite similar.

* The airport station in particular has been slow to cool down as the sun descends in the sky. Minimum on the 28th was 12.1 C versus 3.3 C at the climate station.

The bare terrain of course would not help to radiate heat to space and maybe the nearby frozen ice surface would help the climate station to cool, with the west wind fanning cooler air from the inlet.

It is a surprise to me that there would be such large differences but maybe it can be explained by the ice, bare earth, wind and topography.

It does remind me of the remarkable climate of Kangerlussuaq in western Greenland which frequently records high temperatures of 20 C or more.

But Eureka is further north.

This year too in Siberia has seen some incredible temperatures. As the heat moves further north, dramatic changes will occur the further north you go. The sun does not set and there is plenty of dark bodies to absorb the incoming solar radiation.

A taster of what it will be like when the summer sea ice goes ?   
 

Glen Koehler

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #1 on: June 29, 2020, 02:56:01 AM »
could be be an elevation difference?
They are both down as 10m. Still showing a difference of 7 C beteeen the 2 stations.
       Alternate possibility.  May sound too simple to be true, but it wouldn't be the first time to have incorrect readings from improperly operated weather sensors.  If one of the sensors is missing a radiation shield or does not have an aspiration fan to move ambient air across the sensor, then it can report much higher temperatures than a properly protected sensor.  Or if the sensor is placed near a building, pavement, or (God forbid, but it happens) on a roof, it will give falsely high warnings during sunlight hours.  Did the two sensors agree until direct sunlight returned?

      And there is always the possibility of a sensor for which everything was done right, i.e. properly shielded, aspirated, located and calibrated --- but then it just goes bad.  Temperature sensors are robust, but anything can break.
     When did temperature readings from the two stations begin to diverge?  An abrupt change in readings for one of the sensors could indicate equipment malfunction.
« Last Edit: June 29, 2020, 04:12:28 PM by Glen Koehler »

1rover1

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #2 on: June 29, 2020, 04:10:25 AM »
My understanding is the Environment Canada station is near the coast at 0 elevation.  The Airfield according to Nav Canada is at 83 meters (272 feet)

Then there is, PEARL,  the Polar Environment Atmospheric Research Laboratory (Canadian Network for Detection of Atmospheric Change).  PEARL has three sites: The PEARL Ridge Laboratory 15km from the Eureka weather station at 610m elevation, the 0PAL laboratory next to the weather station and the SAFIRE site which is far from structures for undisturbed measurements.  Couple of links.

https://www.candac.ca/candac/Data/PEARL_Weather/weather.php

http://cnnro.ca/polar-environment-atmospheric-research-laboratory-pearl/#:~:text=PEARL%20has%20three%20sites%3A%20The,from%20structures%20for%20undisturbed%20measurements.




1rover1

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Rubikscube

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #4 on: June 29, 2020, 11:39:04 AM »
Weather forecasts for Eureka supports the notion that there are +20C temps there, and will be for another 48 hours. Don't think it is an error, just very warm.

Rubikscube

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #5 on: June 29, 2020, 11:50:13 AM »
this is the hour by hour recording from the Canadian gov website - cited on Wikipedia - yesterday was just 0.1 C short of the all time record.

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #6 on: June 29, 2020, 01:37:49 PM »
The midnight sun stays just above the southern horizon. Located on a higher ground Eureka Airport might receive more sunshine than the Eureka Climate station at sea level. The inlet is only 1 km wide to the south and terrain on the other side looks hilly.

Also, there are hills to the north and west, which give Airport protection during westerly winds. Eureka Climate gets the ice cold breeze from the inlet.

GAWLab

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #7 on: June 29, 2020, 02:53:46 PM »
I don't know the details of the situation in Eureka, but based on my experience here in Alert, proximity to water will dramatically reduce the temperature.  It's noticeably cooler here standing next to the lakes with ice cover on them than it is just 50 metres away from them.

I'm friends with the current SPM in Eureka, he's been talking about the incredibly high temperatures there all week.  I'll send him a message and point him in the direction of this thread and see what he has to say.
- Kevin
Operator, Dr. Neil Trivett Global Atmosphere Watch Observatory
Alert, NU

Glen Koehler

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #8 on: June 29, 2020, 04:24:22 PM »
    My speculations were for non-professional weather stations.  NOAA or Env. Can. ownership and the photos indicate professional-grade weather stations with technical support, so far less likely to have issues with low-quality sensors, improper placement etc. that not infrequently occur at non-professional stations.

Niall Dollard

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #9 on: June 29, 2020, 07:34:45 PM »

I'm friends with the current SPM in Eureka, he's been talking about the incredibly high temperatures there all week.  I'll send him a message and point him in the direction of this thread and see what he has to say.

Thanks Kevin.

I am very surprised by the size of the differential between the two reporting stations. Maybe, as Glen has suggested, something has gone awry with one sensor and/or shielding.

Below I have plotted the two stations, 71917 and 71613, for the period 12 UTC on 27th to 12 UTC on 29th.

On three occasions on the 27th, there was a difference of over 15 C between the two stations. 

Niall Dollard

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #10 on: June 30, 2020, 11:57:55 AM »
Sentinel image from 27th June overlayed with a plot of the 21Z reports that day. This was at a time when the temperature differential was at its greatest.

paolo

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #11 on: June 30, 2020, 12:48:31 PM »
It seems to me that the proximity to the sea ice of one weather station and the distance of the ice of the other is the decisive element to explain the difference, as well as the absence of wind (or a wind parallel to the valley).

nanning

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #12 on: July 01, 2020, 10:20:20 AM »
paolo, I think that temperature sensors at official weather stations are shielded from the wind. That should not be a factor. I agree that the difference could possibly be the nearby ice at the one, and the perhaps the nearby strip of tarmac/concrete at the other.
Humidity differences?
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paolo

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #13 on: July 01, 2020, 10:41:06 AM »
Nanning,
The wind can cause the air temperature to vary depending on where it comes from, and it is the air temperature that we measure ...
In our case this implies that no strong winds from the interior or from the sea ice are needed, since the temperatures measured at both stations keep the imprint of the proximity of the sea ice in one case and being away from it in the other.

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #14 on: July 01, 2020, 10:40:43 PM »
They both could be working just fine. Rock is really good at retaining heat. When I lived in Page Arizona the town was about 5 C warmer than the surrounding area. Page is built on a solid rock next to lake Powell. The lake was made when they dammed the gorge. The high canyon walls block the sun for part of the day and depth keeps the lake cool.  Near the lake is cooler than the surrounding area. I am not sure about exact temperatures. I don't have any problem believing Ice and rock can create a substantial temperature gradient.

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #15 on: July 01, 2020, 10:52:29 PM »
Despite being a desert with clear skies that allow most deserts to cool quickly at night the rock kept the temperature from cooling much during the night. With 24 hour sun I can imagine it just warms. If you look at the edge of Greenland next to the Lincoln Sea that coast is solid rock. When the sun is shining it gets very warm despite it being surrounded by ice year round. Just look at nullschool the warmth doesn't seem to come from anywhere.

Csnavywx

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #16 on: July 03, 2020, 04:21:03 PM »
Temperature differentials like this can also be driven by sea breezes, secondary circulations that set up when differences in density arise from differential solar heating and/or thermal inertia. I typically deal with one on a daily basis at the station I work at. A temperature drop of a few degrees often occurs. The difference here is that the sun never sets and the difference is very large due to ice. I would imagine that sea breeze to be very persistent as long as the gradient wind doesn't get strong enough to wash it out.

HapHazard

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #17 on: July 08, 2020, 11:05:37 PM »
Hey GAWLab how's it going up there now?  :o

blumenkraft

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #18 on: July 09, 2020, 07:35:35 AM »
Kevin might have thrown out his winter jacket by now...

oren

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #19 on: July 09, 2020, 07:55:44 AM »
Remember Kevin is in Alert, where temps have dropped sharply in the last few days, while Eureka has remained warm throughout.

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #20 on: July 09, 2020, 08:08:38 AM »
It looks to me that the measurements are accurate - this is high quality equipment that survives a brutal winter - and the temperature differences are explained by a strong ground inversion near the sea ice.

"My understanding is the Environment Canada station is near the coast at 0 elevation.  The Airfield according to Nav Canada is at 83 meters (272 feet)"

Niall Dollard

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #21 on: July 09, 2020, 12:20:28 PM »
Hello folks,

I did contact EC Canada and I received a reassuring reply that all is well. This basically confirms what we have outlined in this thread. It is always nice to get confirmation and thanks to EC Canada.

       Hello Niall,

 
 Thank you for sending your message to Environment and Climate Change Canada.  I checked with one of my colleague familiar with the weather in Eureka and here’s the reply he sent me:

  “While the stations are within 2 KM of each other, they differ from each other physically.  NAV Canada’s station (71613) is situated on a hill 30m higher in elevation than our surface station (71917; as well, our surface station is located quite a lot closer to the fjord. Depending on which direction the wind blows we have seen a large discrepancy between the two sites due to their locations.

I looked over our surface site date between June 21 and July 3 and do see some temperature swings of about 5C between the max and min reported temps, but these are similar to the swing between max and min we see in Svartevaag and Alert over the same period.

We have a climate program on site with different instruments located about 3m away from our surface sensors, I spoke with the staff on site and they mentioned that the values differ by about 0.5c at times but are generally similar to our surface station values.

 The equipment in the Eureka surface station is standard across Canada and failures are extremely rare.  We compare the sensors against our regional standard at least once a year and require tolerances of +/- 0.5 degrees.  The last comparison was done in August of 2019 and showed a deviation of 0.05 degrees from our reference.  I am not sure of Nav Canada’s maintenance schedule, or if they go out to check their equipment at all.

 For the reasons discussed, I am confident in the accuracy of our sensors and that these temperatures are indeed correct.”





blumenkraft

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Re: Temperatures at Eureka, Nunavut, Canada
« Reply #22 on: July 09, 2020, 01:01:08 PM »
Cool! Thanks, Niall. :)