Permafrost: Working with Real Data Student Study Sheet

The soil temperature data you will be examining came from Smith Lake Site 1 near Fairbanks, Alaska. It was collected using temperature probes placed at 9 different depths during 1998 and 1999.

3. Using a metric ruler, draw a 10 cm long line. That’s how far under the surface the first temperature was placed. The deepest probe was at 100cm which is 39.37 inches or 3 feet 3.37 inches.

6. Describe what happens to the average temperature values as the depth of the probe increases for each year.

7. Describe what happens to the minimum temperature values as the depth of the probe increases for each year.

8. Describe what happens to the maximum temperatures as the depth of the probe increases for each year.

9. Which values, average, maximum, or minimum temperature should be examined to determine if permafrost formed in 1998-1999? Why? Remember, permafrost is rock or ground that remains at or below 0^◦C for at least 2 years.

10. Based on the maximum temperatures, do you think permafrost formed during the 1998-1999 period? Why?

1. Describe what happens to the average temperature values as the depth of the probe increases for each year.

2. Describe what happens to the minimum temperature values as the depth of the probe increases for each year.

3. Describe what happens to the maximum temperatures as the depth of the probe increases for each year.

4. Do the charts show the same trends you formulated from the data table? If not, explain.

6. What other trends or things do you think the data or charts tell you about conditions at Smith Lake Site 1 in 1998 and 1999?

7. Using Chart 1- Yearly Average Temperatures, estimate the average soil temperature at the surface (0cm) for 1998. ________ 1999 _______

1. During which months in 1998 did the average soil temperatures stay below 0^◦C? In 1999?

2. During which months in 1998 did the maximum temperatures stay below 0^◦C? In 1999?

3. Are the trends you identified for average, minimum, and maximum temperatures in Part I using the yearly data reflected in the monthly data for 1998 and 1999? Explain.

4. Looking at only the maximum temperatures in Tables 2 and 3, why do you think some of the values are highlighted in red and others in blue?

5. Look at the maximum soil temperatures for 1998, Table 2. You’ll notice that the amount of red in the rows changes during the year. Remember the red indicates soil temperatures that were below freezing. Are there any depth columns that stay red for all 12 months of 1998? Which ones?

6. Now look at the maximum soil temperatures for 1999, Table 3. Are there any columns that stay red for all 12 months of 1999? Which ones?

7. Based on the maximum temperatures at any depths for 1998 and 1999, did permafrost exist during this period? Remember that permafrost is any soil or rock that stays below freezing for a 2-year period.

8. Based on the maximum soil temperatures, is there an active layer anytime during 1998? 1999? Remember the active layer is soil or rock that thaws (gets above freezing) at some time during the year.

9. In which month does the data indicate the active layer first appears in 1998? ____________ In 1999? ___________

10. In which month does the data indicate the active layer first disappears in 1998? ____________ In 1999? ___________

1. Look at the Monthly Average Values for Smith Lake Site 1 for 1998 and 1999 (Charts 4 and 5). At what depth do all of the monthly average soil temperatures fall below freezing in 1998? _________ In 1999? _________

2. Describe one other trend or thing you think the Monthly Average Values Charts 4 and 5 tell you about conditions at Smith Lake Site 1 in 1998-1999.

3. Look at the Monthly Maximum Temperatures for 1998 and 1999 (Charts 6 and 7). At what depth do all the monthly maximum soil temperatures reach or fall below freezing for all 12 months of the year in 1998? In 1999?

5. Describe one other trend or thing you think the Monthly Maximum Temperature Charts 6 and 7 tell you about conditions at Smith Lake Site 1 in 1998-1999.

1. Use the maximum temperatures and the depth columns in Tables 2 and 3 to complete the following table:

NOTE: Since surface (0cm) soil temperatures were not recorded, a value of 10cm was assigned to any months in which the temperature at 10cm remained below freezing. For all of the other months, the maximum active layer depth is considered to be the depth at which the soil first reaches freezing. For example, for the month of April the probe at 10cm indicated temperatures above freezing and the probe at 25 cm indicated temperatures below freezing. The maximum depth of the active layer for April was 25cm. The actual maximum active layer depth was somewhere between 10 and 25 cm, but since no probe was placed at that depth, the highest value was used. Bolded values are provided in the student version of the table.

Maximum Active Layer Depth (cm)
	1998	1999
Jan	10	10
Feb	10	10
Mar	10	10
Apr	25
May
June
July
Aug
Sept
Oct
Nov
Dec

2. Based on the completed table, what was maximum depth of the active layer in 1998? __________ In 1999? ________

3. Using the data in your completed table, prepare a bar or line chart comparing the maximum active layer depths for 1998 to 1999 and label it Chart 8.

4. Based on your chart, what is the maximum depth of the active layer in 1998?_______ In 1999? ________

5. Write a statement that summarizes your answers to #14 about the thickness of the active layer in 1998 compared to 1999.

6. Remembering that permafrost begins at the maximum depth of the active layer measured during a 2-year period, write a statement that describes the permafrost at Smith Lake Site 1 for 1998-1999.

Permafrost scientists monitor soil temperatures and other variables for long periods of time to determine the extent of the permafrost and analyze the impact of climate changes on permafrost. The data analysis is a complex process and they sometimes use permafrost models and visualization tools to help them. Below are a few Internet sites that show the results from long-term studies and a study that was just started by a professor from the University of Alaska at Fairbanks. There is also a link to an article about a permafrost visualization tool. Check them out!