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  1. #51
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    Hi everybody!

    Last weekend I went to collect data from my logger. Winter has definitely gone: Sämtisersee had it's last frost on May 20 with -0.8 °C and Hintergrappelen on June 9 with -1.4 °C (plus an impressive -4.5 °C on the night before).

    Exceptional in the other direction was the night from June 22 to June 23. This was the warmest night in eastern Switzerland since the beginning of automatic measurements in 1981. The highest minimum has been recorded at the border of Lake Constance: A minimum of 25.2 °C has been measured, the old record was 20.9 °C. I assume that highest night temperatures in Italy are higher than here in Switzerland on the northside of the Alps, but nightely minima of >25 °C probably also not bad for Italy...

    Beside the very warm airmass the overcast sky was the main reason for the warm night. What happened in the (not so frosty) frost hollow in the Alpstein region?


    The blue line shows Hintergräppelen, the yellow line Sämtisersee lower station and the orange line Sämtisersee upper station.

    It was really surprising for me to see that at Lake Sämtis a tropical night (temperature > 20 °C between 18 UTC and 6 UTC) was only just missed. Hintergräppelen dropped > 7 K to ~15 °C due to a clear spell.

    Some additional details are presented under http://kaltluftseen.ch/2017/07/19/tr...napp-verfehlt/

    Best regards, Stephan


  2. #52
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    Citazione Originariamente Scritto da Stephan Visualizza Messaggio
    Hi everybody!

    It was really surprising for me to see that at Lake Sämtis a tropical night (temperature > 20 °C between 18 UTC and 6 UTC) was only just missed. Hintergräppelen dropped > 7 K to ~15 °C due to a clear spell.
    Unbelievable minimum temperature in Lake Samtis!

    In our Campoluzzo frost hollow that night we had a "strange" minimum (due to overcast sky) of around 8°C.
    In the other nights, before and after, night's temperature felt down between -3°C and +1°C, almost every day.
    Actually, throughout a normal summer in that frost hollow we have 2 nights on 3 with frost

    Exceptional value also in Lake Constance. You are right, also in Italy that value would be strange.

  3. #53
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    Citazione Originariamente Scritto da Bruno Visualizza Messaggio
    In our Campoluzzo frost hollow that night we had a "strange" minimum (due to overcast sky) of around 8°C.
    In the other nights, before and after, night's temperature felt down between -3°C and +1°C, almost every day.
    Actually, throughout a normal summer in that frost hollow we have 2 nights on 3 with frost
    Dear Bruno

    2 of 3 nights with frost is remarkable! At Sämtisersee (lake) as well as in Hintergräppelen (wetlands) we are far away from these values. I assume that Campoluzzo is a very dry frost hollow? Here the values from June to September for Hintergräppelen:






    Since last week there is a combined temperature/humidity-senor with real time transmission in operation at Hintergräppelen. It have the opportunity to test an IoT (Internet of Things) unit which uses Low Power Network (Lorawan) for data transmission: https://www.decentlab.com/products/a...diation-shield. With this technology data transmission can be realized at very reasonable prices. The experiment will show if the unit also works at very low temperatures and how good the quality of the temperature data is compared to the datalogger. Depending on the results and the funding a permanent operation is possible. Here is a link to the values: https://kaltluftseen.ch/daten-von-ka...lle-messwerte/

    The humidity data will at least partly explain the low performance of Hintergräppelen due to the available moisture in the area...



    Best regards, Stephan

  4. #54
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    Citazione Originariamente Scritto da Stephan Visualizza Messaggio
    Dear Bruno

    2 of 3 nights with frost is remarkable! At Sämtisersee (lake) as well as in Hintergräppelen (wetlands) we are far away from these values. I assume that Campoluzzo is a very dry frost hollow?
    Yes, it is absolutely a very dry frost hollow, similar to other frost hollows in Prealps' Northeastern Italy.
    The high plateau of Pale di San Martino (2500-2700 m a.s.l.) doesn't show such lows in summer.
    Here minumum temperatures of last summer in Campoluzzo (Giu-Lug-Ago means June-July-August). 47 frost days of 92 summer days
    Immagini Allegate Immagini Allegate

  5. #55
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    Citazione Originariamente Scritto da Stephan Visualizza Messaggio
    Since last week there is a combined temperature/humidity-senor with real time transmission in operation at Hintergräppelen. It have the opportunity to test an IoT (Internet of Things) unit which uses Low Power Network (Lorawan) for data transmission: https://www.decentlab.com/products/a...diation-shield. With this technology data transmission can be realized at very reasonable prices. The experiment will show if the unit also works at very low temperatures and how good the quality of the temperature data is compared to the datalogger. Depending on the results and the funding a permanent operation is possible. Here is a link to the values: https://kaltluftseen.ch/daten-von-ka...lle-messwerte/
    Fantastic news, Stephan.
    It's looks a very interesting monitoring and transmission system. We will see, as you said, how does it work with extreme winter temperatures...
    So we have another "real-time frost hollow", excellent.

    Can I put (only in very cold days) its minimum temperatures in this list? http://forum.meteotriveneto.it/showt...onfronto/page8

    Warmest regards

  6. #56
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    Citazione Originariamente Scritto da Bruno Visualizza Messaggio
    Fantastic news, Stephan.
    It's looks a very interesting monitoring and transmission system. We will see, as you said, how does it work with extreme winter temperatures...
    So we have another "real-time frost hollow", excellent.

    Can I put (only in very cold days) its minimum temperatures in this list? http://forum.meteotriveneto.it/showt...onfronto/page8

    Warmest regards
    Dear Bruno,

    No problem to use the values from the Realtime-Sensor at Hintergräppelen in your list!

    Perhaps a few addtional remarks regarding this sensor and the communication system that is used (I noticed the contributions under http://forum.meteotriveneto.it/showt...-corso/page176 but didn't wanted to contribute in English there since it is an Italian forum).

    Gasgallo is absolutely right: IoT is a generic expression not to say a buzzword: machine-to-machine-communication is something that is state-of-the-art in meteorological and climatological monitoring since more than 30 years. The attractive aspect when using this sensor-telecommunication-unit is the fact that a dedicated network is used: it's a Low Power Network (LPN) which uses Lorawan as a network protocol. This network is dedicated for bidirectional transfer of small data amounts (which is typical for e.g. meteorological sensors). In Switzerland there are two networks available: a free, community based one (https://www.thethingsnetwork.org/ --> some nodes are also available in Italy) and a commercial one (http://lpn.swisscom.ch/i/). The Swisscom LPN-Network has a quite good coverage - at least it works in Hintergräppelen... The main advantages are the very low power consumation for the sender of the unit (normal battery!) and very reasonable costs (CHF 22/year = some €19/year for data transmission of battery status, relative humidity and temperature every 10 minutes). There are also some drawbacks:
    • since it is a test device, I cannot make adaptions for a better ventilation
    • there is no datalogging on the device: the completeness of the time series depends crucially on the availability of the network. My first experience with the device is that 1 or 2 values per 1 or 2 days are missing - and it would be a pitty if this is an extraordinary minimum...


    My draft conclusion is that it is very attractive to have real time values available - but with the current setup it is not a replacement for the datalogger which will remain as reference.

    Best regards, Stephan

  7. #57
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    winter is here!

    Hi everybody,

    just a short update: the frost hollows in Northeastern Switzerland are finally in winter-mode: some 50 cm of snow last Sunday and Monday delivered a good basis for the first notable minimas. At Hintergräppelen I had minimas of -21.9 °C, -21.5 ° and again -21.5 °C on 3 consecutive days. Even more notable is the first Persistent Cold Air Pool phase on November 15 with a maximum of -10.5 °C.

    No data from Sämtisersee so far (since no realtime sensor is present) but on the following video you can see that the lake is freezing over (it usually needs abundant snowfall to cool down the lake and 1 - 2 days with minima < 10 °C for the formation of an ice layer):



    hintergräppelen_20171112_16.png

  8. #58
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    Thanks Stephan for this last update and for your previous reply

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