Investigation of permafrost sensor dynamics

Permafrost soils are an important part of the whole climate and environmental system as they play an important role in storing carbon and water. As permafrost makes around 15 % of the global land cover the amount of stored carbon and water is not negligible. These types of soils provide a direct source of water for plants in severe drought areas, during summer and keep surplus water in the soil until the next season. Furthermore the trapped carbon is of high concern as the increasing global temperature could cause the release of this undesired substance. To be able to determine the current state of the permafrost thickness and its evolution in time it is important to have a precise measurement of permafrost temperature. Commonly the measurements are performed by temperature sensors that are placed in a narrow drill hole several meters deep. The temperature is recorded continuously during the whole year. The problematic point of this measurement is the day/night cycle, during which the temperature elevates due to increasing solar radiation. This creates an oscillating behaviour of measured temperature that is affected by the sensor dynamics that is different form sensor to sensor. In order to be able to have reliable and traceable permafrost temperature data the different sensor dynamics need to be determined and included into the measurement uncertainty. This paper presents an experimental measurement method by which means it is possible to determine the different permafrost sensor dynamic it the range from 30 °C to +30 °C. The paper furthermore discusses the uncertainty contribution from this sensor property and furthermore compares the dynamics of different tested sensors.