Borehole Temperatures for March 2019

I know there isn't much data yet, but I want to give a monthly report on my newest experiment.

The borehole is a four-foot deep hole in our want soil. Using LM335 temperature sensors, a PICAXE is recording the temperature at one foot increments every hour. Here's what the data for March looks like.

The temperature on the surface is strongly affected by the sun, even though the sensor head is covered worth a Styrofoam chest.

The diurnal temperature change one foot below the surface is only about 3 degrees Fahrenheit. We'll have to see how it changes over the course of a year.

At two feet and deeper, the temperature is warming up slightly after the hole allowed cold air to enter.

At three-feet deep, the temperature is warming up from the hole being dug during a cold day.

It appears the temperature four feet deep is recovering from the hole I dug in cold weather.