At the St. Paul Climatological Observatory there is a plot that is kept bare of all vegetation. We measure the temperature of the soil under this bare plot at the following depths: 1, 5, 10, 20, 40, 50, 60, 80, 100, and 120 centimeters.
We also measure the temperature of the air above this plot at the following heights above the soil surface: 0, 4, 8, 12, 16, 20, 25, 30, 40, and 50 centimeters.
During the winter some or all of the thermocouples used to measure the temperature may be buried in the snow so that they are measuring the temperature within the snow pack. As the snow pack increases in depth, the thermocouples nearest the soil surface will be insulated to a greater extent from the air temperature fluctuations above the snow surface.
The thermocouples used for measuring the air/snow temperature above the soil surface are about 15' south of the thermocouples used to measure the soil temperature. Thus there may appear to be a discrepency or discontinuity in readings passing from the air/snow into the soil. Variation in snow depth across the plot will affect the temperatures.
Representation of the mast.