Permafrost – Looking at Real Data 

Student Study Sheet - KEY 

Name __________________________________                                    Group No. _____________

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.

Use the data presented in Table 1 to answer the following:

1.  Describe the types of values that are presented in the table.

Average, minimum and maximum temperatures in degrees Celsius a at 9 different depths from 10cm to 100cm for 1998 and 1999.

2.  Without using a ruler, draw a line that you think is 10cm long.

Answers will vary

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.

4.  At what depth was the average temperature the highest for 1998? __10cm__

5.  At what depth was the average temperature the lowest for 1998?  ___75cm_

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

 In 1998, the average temperatures decrease to a depth of 80cm then increase. In 1999, the temperatures to a depth of 50cm, increase at 80 and 85cm, decease at 90cm, increase at 95 cm and decrease at 100cm.

 

In 1999, the average temperatures decrease to a depth of 50cm, increase to a depth of 95cm and then decrease at 100cm.

In 1998, the minimum temperatures increase as the depth increase

In 1999, the minimum temperatures increase as the depth increases.

In 1998, the maximum temperatures decrease to a depth of 90cm then increase at 100cm.

In 1999, the maximum temperatures decrease to a depth of 90cm then increase at 100cm.

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.

Maximum temperature should be used to make sure that the ground temperature never rose above freezing.

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

 Yes, because there are depths at which the maximum temperature never rose above freezing.

Use Charts 1, 2 and 3 to answer the following:

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

In 1998, the average temperatures decrease to a depth of 80cm then increase. In 1999, the temperatures to a depth of 50cm, increase at 80 and 85cm, decease at 90cm, increase at 95 cm and decrease at 100cm.

In 1999, the average temperatures decrease to a depth of 50cm, increase to a depth of 95cm and then decrease at 100cm.

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

In 1998, the minimum temperatures increase as the depth increases

In 1999, the minimum temperatures increase as the depth increases.

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

In 1998, the maximum temperatures decrease to a depth of 90cm then increase at 100cm.

In 1999, the maximum temperatures decrease to a depth of 90cm then increase at 100cm.

Should be yes. Otherwise, you need to talk about they think they saw.

5.  Which was easier for you interpret, the table or the charts?

 Answers will vary

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?

Answers will vary, but could include things like: 1999 was colder than 1998 (an inference that might or might not be supported by air temperature data) or the ground got colder in 1999 than in 1998. This is a great chance to talk about what else they might want to know or have measured. In an ideal world scientists would have the funding, the time and the equipment to measure and record everything they might want to examine. But in the real world, they have to plan well and pick and chose what they can do and hope that they don’t have any equipment malfunctions or failures.

7.  Using Chart 1- Yearly Average Temperatures, estimate the average soil temperature at the surface (0cm) for 1998.  ___0.4 ^◦C   _ 1999 __-0.3^◦C _

Use Tables 2 and 3 to complete the following:

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

1998 – Jan, Feb, Mar, Apr, Oct, Nov, and Dec

1999 – Jan, Feb, Mar, Apr, May, Nov and Dec

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

1998- Jan, Feb, Mar, Nov, and Dec

1999- Jan, Feb, Mar, Apr and Dec

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

Yes and no. The average temperature for winter months increases as depth increases while the average temperature for summer months decreases as depth increases. The minimum temperatures sometimes increase with depth and sometimes decrease with depth. The maximum temperatures sometimes increase with depth and sometimes decrease with depth.

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?

All of the red values are above freezing and all of the blue are below freezing. This was done to make it easier to determine if permafrost existed and the maximum depth of the active layer.

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?

Yes, the columns for 80, 85, 90. 95 and 100 cm are red for all 12 months.

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?

Yes, the columns for 75, 80, 85, 90. 95 and 100 cm are red for all 12 months.

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.

Yes, there are depths (column stays red) at which the soil temperature never rose above freezing at any time in 1998 or 1999.

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.

Yes, in 1998 there is an active layer during the months of Apr, May, June, July, Aug, Sept and Oct.

Yes, in 1999 there is an active layer during the months of May, June, July, Aug, Sept and Nov.

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

1998 - April               1999 – May

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

1998 – December      1999 – November

Use Charts 4, 5, 6 and 7 or your charts to answer the following:

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? _________

1998 – 80cm     1999 – 70cm

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.

Answers will vary.

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?

1998 – 80cm    1999 – 75 cm

4.  Did permafrost exist at Smith Lake site 1 in 1998-1999? __Yes___ Why?

Because the maximum soil temperature never rose above freezing at some depths for several months during both years.

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.

Answers will vary.

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.

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

1998 – 80cm   1999 – 75cm

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?

1998 – 80cm during the months of August and September

1999 – 75cm during the months of August, September and October

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

The active layer in 1998 was thicker (max. of 80cm) in 1998 than in 1999 (max. of 75).

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 existed at Smith Lake Site 1 at a depth of 75-80cm 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!

Permafrost study Fairbanks, Alaska (measured 1955-2003, calculated 1930-1955)

Permafrost study Northern Mongolia (1983-2000

Stories about Kenji Yoshikawa’s Yukon River project

• Project Overview
• A Day in the Life

Permafrost Visualization Matures – permafrost monitoring goes high-tech