Soil temperature patterns

Today we had two main jobs: (1) cleaning and setting up the snow lysimeters for the coming winter season, and (2) visiting the zero-order basin to download the soil temperature data.

Above you can see the data for soil and spring water temperature for a period of three years obtained about 10 years ago. The seasonal pattern is clear, with stronger fluctuations in soil temperatures nearer the surface, and we can also see the impact of the seasonal snow cover very clearly during December to April. The sudden rise in soil temperatures in spring can only occur after the snow cover has melted off.

Also plotted in the figure above is the spring water temperature, which has a smaller range of variation compared to the soil temperatures, ranging only between about 9.5 and 13 degrees Celsius. This is because the spring water is flowing out from much greater depths where ground temperatures are almost constant year-round at approximately the mean annual air temperature.

Below you can see the data downloaded for May to December 2013. During the summer season the temperatures nearer the surface are normally warmer due to the influx of energy with warmer air temperatures. However, the chart here shows the 20 cm and 40 cm depths to have almost the same temperatures, with the 40 cm depth even a little warmer. As the monitoring has been ongoing for over 10 years now, I suspect that the sensor wires have been subjected to stresses and movement within the soil column, causing problems with data reliability. The 100 cm depth data was suspect and removed from the chart. It is time to renew and re-install the monitoring equipment.