Modeling soil temperature at a depth of 5ft

In summary: It is a significant factor, and should be considered in any temperature estimation.The temperature swings from -35C in the winter, to +42C in the summer, obviously this doesn't make a lot of sense.The problem with this temperature swing is that it is not based on an average yearly temperature, but rather a temperature swing calculated using a thermal diffusivity of between .8 and .15. This might be okay for a summer temperature, but it doesn't make sense for a winter temperature.
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Hello everyone,

This isn't really my area of expertise, so I am looking for a bit of guidance. I wish to estimate the temperature underground at a depth of 5ft. The climate is Saskatchewan (Canada) so it is covered with snow in the winter, and fairly hot in the summer. There is no tree coverage, only grass. The widest average temperature swings are from about -28C to +32C.

Currently, I'm attempting to apply the model described here: http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/cbd/building-digest-180.html#archived [Broken]

My results however are pretty questionable. I am using an average yearly temperature of 2.6C, and a thermal diffusivity of between .8 and .15. I've calculated that the temperature swings from -35C in the winter, to +42C in the summer, obviously this doesn't make a lot of sense. Can anyone point me in the right direction for estimating underground temperatures? The model doesn't need to be accurate either, +/- 10 degrees is pretty acceptable.

Thank you,
 
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  • #2
I've calculated that the temperature swings from -35C in the winter, to +42C in the summer, obviously this doesn't make a lot of sense.
Looks like a wrong sign in the exponential function.
 
  • #3
I think the problem is with the value "A". " A is the difference between the maximum and minimum temperatures for the period", shouldn't it be the difference between the max/min temp and the average (The amplitude)? I used 60 for A, but I think it should be 30 instead. 2.6C average, with a 32.6C max and 27.4C min. This gives me a temperature swing 5ft below ground of about +23C and -17C. Do these values seem reasonable? What about the snow coverage? Snow is an excellent insulator.
 
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Jyan said:
I think the problem is with the value "A". " A is the difference between the maximum and minimum temperatures for the period", shouldn't it be the difference between the max/min temp and the average (The amplitude)?
I agree with you. The web page description is wrong.

Do these values seem reasonable?

Check that you can reproduce the numbers in Table 1.

What about the snow coverage? Snow is an excellent insulator.

So is earth. Since the web page doesn't mention snow, maybe it doesn't make much difference. But I'm not an expert on soil mechanics or civil engineering.
 
  • #5
Insulating snow is mentioned directly under Table I, and the effect upon the average soil temperature being elevated from that of a surface with no surface snow.
 

1. What is the purpose of modeling soil temperature at a depth of 5ft?

The purpose of modeling soil temperature at a depth of 5ft is to understand and predict the temperature changes in the deeper layers of soil. This information can be useful for a variety of applications, such as agriculture, construction, and climate research.

2. How is soil temperature at a depth of 5ft measured?

Soil temperature at a depth of 5ft can be measured using specialized sensors, such as thermocouples or resistance thermometers, which are inserted into the soil. These sensors record temperature data over time, which can then be used to create a model.

3. What factors influence soil temperature at a depth of 5ft?

The main factors that influence soil temperature at a depth of 5ft include the amount of sunlight, air temperature, moisture content of the soil, and the type of soil. Other factors such as vegetation cover, slope, and depth of the water table can also have an impact.

4. How accurate are models of soil temperature at a depth of 5ft?

The accuracy of models for soil temperature at a depth of 5ft can vary depending on the complexity of the model and the quality of the data used. Generally, models can provide a good estimate of temperature trends, but there may be some error in predicting exact values.

5. How can modeling soil temperature at a depth of 5ft aid in climate research?

Modeling soil temperature at a depth of 5ft can provide valuable data for climate research, as it can help to understand the impact of changing temperatures on soil processes and the overall ecosystem. This information can also be used to improve climate models and predictions for future temperature changes.

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