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Swiss frost hollows: kaltluftseen.ch

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  • #46
    Hi,

    Sorry for interrupting with information about other countries in this topic. Short reaction on Bruno's message: I think -45 would already be fantastic. It seems that most of the differences are between 25 and 28 degrees with free atmosphere. Once I had 31 degrees difference. Cryotemp is a very good datalogger except for the maintenance.
    My friends in Utrecht University are specialised in Arctic climate. In June I will try to visit them to ask about possibilities to hire one of their older stations which they used in Antarctica. I will let you know the outcome.

    My friends in Hungary posted a very nice movie about the snowstorm on April 20: https://vimeo.com/214358842 In the Bükk mountains, around 750 to 850m, they had 90 cm of snow. Unfortunately electricity broke down and the automatic station fell out.

    Bye

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    • #47
      Originariamente inviato da Karel Visualizza il messaggio
      My friends in Hungary posted a very nice movie about the snowstorm on April 20: https://vimeo.com/214358842 In the Bükk mountains, around 750 to 850m, they had 90 cm of snow. Unfortunately electricity broke down and the automatic station fell out.
      Unbelievable snowfall!
      Thanks Karel for sharing it

      About possible extreme cold in your doline in Romania...actually I didn't get news of very low temperatures in last January in the "famous" cold villages of this country (like previous winter) so it is possible that wind and cloudiness had disturbed radiative coolings there.
      However, we will see...

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      • #48
        Hi Karel, hi to all

        Your info is in no way an interruption - thanks for sharing it with us! Seems that the further east, the more impressive the snow cover was... There is not much information available about the frost hollows in Bükk Fennsik available on the Internet (or - perhaps more probable - not that easy to find for people like me without any knowledge of Hungarian...) - what is the best resource to learn more about this region?

        I look foreward to your results from Romania and hope for a continuation of the measurements there!

        Best regards, Stephan

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        • #49
          New data / frost damages at Hintergräppelen

          Dear all

          I visited the two frost hollows in the Alpstein on Ascension Day in order to collect the latest data. In the morning I visited Sämtisersee - a beautyful scenery:



          Here are the latest data from March to May 25th:





          The Hintergräppelen frost hollow was even colder (I already presented the movie from my visit on April 21):





          In Hintergräppelen the cold spell in the second half of April resultet in frost damages at the spruce trees which are situated in the frost hollow: The upper limit of the red colored trees is quite good visible on the following pictures and corresponds more or less with the upper limit of the frost hollow:



          From March 17 to April 18 no daily minimum below -10 °C have been observed, but in the second half of April on 5 days temperature fell below -10 °C (including a minimum of -27.3 °C and one of -21.8 °C). It seems that this frost period and the intensive insolation at the same time are the reasons for the reddening of the needles. Here are two interesting arcticles about this topic (unfortunately only in german): http://www.waldwissen.net/waldwirtsc...aeden/index_DE and http://szf-jfs.org/doi/pdf/10.3188

          Best regards, Stephan

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          • #50
            Interesting topic, Stephan! The damages of severe frost on spruces are really impressive and educational.
            In fact the reason of lack of vegetation at the bottom of many dolines is not the extreme cold in winter (all is covered by snow and however the trees are in "ibernation") but the very low temperatures in April or May, when, without snow at ground, there is the vegetative aweaking (especially for very little plants)

            Cheers
            Bruno

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            • #51
              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

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              • #52
                Originariamente inviato da Stephan Visualizza il 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.

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                • #53
                  Originariamente inviato da Bruno Visualizza il 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

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                  • #54
                    Originariamente inviato da Stephan Visualizza il 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
                    File allegati

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                    • #55
                      Originariamente inviato da Stephan Visualizza il 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

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                      • #56
                        Originariamente inviato da Bruno Visualizza il 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

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                        • #57
                          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

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

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