Permafrost – Working with Real Data

 

 

Estimated time for completion: 3 – 40 minute class periods 

 

This simplified investigation examines a 2-year data set of soil temperatures collected at 9 depths at Smith Lake near Fairbanks, Alaska. The data was collected as part of a 5-year study conducted at 3 sites at Smith Lake. The 2-year data set was chosen because it contains no gaps or values the lie outside of reasonable parameters due to equipment malfunction or failure. The objectives are to determine if permafrost formed during the 2-year period and the maximum depths of the active layer. The focus of this investigation is to reinforce permafrost and active layer concepts by applying them to real data.

 

Background 

Permafrost is not defined by soil moisture content, overlying snow cover, or location; it's defined solely by temperature. Any rock or soil remaining at or below 0°C for two or more years is permafrost. Permafrost can contain over 30 percent ice, or practically no ice at all. It can be overlain by several meters of snow, or little or no snow. Understanding permafrost is not only important to civil engineering and architecture, it's also a crucial part of studying global change and protecting the environment in cold regions. Despite its name, permafrost is characterized by its instability. It is often covered by an active layer that regularly melts. Although permafrost can be thousands of years old, it is sometimes newly formed or about to melt, and it often exists close to its melting point. The active layer thaws each summer and freezes each winter, while the permafrost layer remains below 0°C.

 

Permafrost scientists use a variety of methods and equipment to monitor and map permafrost. Some drill bore holes of varying depths in the ground and place probes and sensors at increasing depths down the hole. Others insert metal rod probes into the ground at increasing depths. Still others analyze remote sensing data.  Some studies may simply record the soil temperatures at the different depths to determine the thickness of the permafrost and active layer while others record an array of measurements including but not limited to soil moisture, vegetation and soil composition. Most recent studies focus on determining the impact of climate change on the extent and thickness of the permafrost and the active layer.

 

Scientists collect permafrost data over different periods of time for analysis. The main criteria for monitoring and mapping permafrost are: mean annual ground temperatures, depth of the active layer, depth of the permafrost bottom and gradient of permafrost temperatures.  Analysis of the values is a complex process Links to two long-term study results are provided in the Resources listed at the end of this investigation. Links are also provided to information about a recently initiated study in Alaska that involves local schools in data collection.  Permafrost data exists for some locations as far back as the 1950’s.  A link to information concerning the development use of a permafrost visualization tool is provided in Resources.

 

 Materials List:   

           

Documents are provided in 4 formats:

 

NOTE: If students have the ability, access, and time to use a spreadsheet program, use the text documents.  Otherwise, use the prepared tables and charts. An intermediate student study sheet is provided, but may contain items that may not be suitable for the more advanced (text document) student. What the more advanced students are required to can vary in scope. They could simply enter, examine, graph, and prepare the active layer graph using similar steps described in the student study sheet. Or they could be required to examine the data and develop their own plan for determining the average maximum depths of the active layer during 1998-1999 and produce all of the spreadsheets and charts to support their results.

 

Documents:

 

NOTE:  Chart 8 and the Maximum Active Layer Depths 1998-1999 pdf and text documents are provided for reference only and should not be given to the students. During the course of this investigation, students will prepare similar documents. Additional charts could be withheld if a desired outcome is to have students prepare their own charts.

 

Procedure

 

 

Prior to beginning the investigation:

·         Access, review and print or download classroom sets of the needed documents. To reduce printing costs and time, the sets, with the exception of the student study sheets, can be laminated to protect them for later use.

·         Access the Resources sites at the end of this investigation and decide what, if any, information you want to share with your students.

·         Review permafrost and active concepts. Discuss the importance, impact implications of permafrost and permafrost changes.

·         Discuss the objectives and background of the investigation.

·         Do a Google Map search to locate Smith Lake, Fairbanks, Alaska or find it on a map of Alaska.

·         Check the weather in Fairbanks. The temperatures in Fairbanks can get very warm in the summer and very cold in the winter. Students may think that permafrost cannot exist there or exists all the time at the surface. Have the students predict what they think the average, maximum, minimum temperatures in degrees Celsius might be at Smith Lake over a year.  Record their predictions on the board.  If students are not comfortable working in degrees Celsius, a review of the relationship between the Fahrenheit and Celsius temperature scales might be needed.  A simple reminder that water freezes at 0â—¦C and boils at 100â—¦C may be sufficient. Providing average, maximums and minimum temperatures in â—¦C for your home town or area would be helpful, too. 

 

 

 Weather Facts for Fairbanks

·         Lowest Temperature ever recorded: -55.4â—¦C (-66â—¦F) on Jan. 14, 1934

·         Average January Low: -28â—¦C (-19â—¦F)

·         Average January High: -19â—¦C (-2â—¦F)

·         Average July Low: 12â—¦C (53â—¦F)

·         Average July High: 22â—¦C (72â—¦F)

·         Average Yearly Temperature for 1961-1990: -2â—¦C (26.9â—¦F)

·         Distribute Students Study Sheets and documents. Distribute the tables and related charts in sequence and during the course of the investigation to prevent confusion.

 

Part I: Examining Yearly Data Data Table 1 and Charts 1, 2 and 3 

 

Estimated time required: 1-40 minute class period to complete Parts IA and IB if using prepared charts. If students are preparing their own graphs by hand, they can start them in class and complete them and Part IB of the Student Study Sheet as homework.

 

Part IA: Examining Yearly Data Table 

 

1.  Before giving the students the data table, ask the students to predict what they think the average, maximum, minimum temperatures in degrees Celsius might be in Fairbanks, Alaska over a year.  Record their predictions on the board.  If students are not comfortable working in degrees Celsius, a review of the relationship between the Fahrenheit and Celsius temperature scales might be needed.  A simple reminder that water freezes at 0â—¦C and boils at 100â—¦C may be sufficient. Providing average, maximums and minimum temperatures in â—¦C for you home town or area would be helpful or give them everything except the average temperature information from the Weather Facts above.

2. Remind the students that they are going to be examining soil temperatures, not air temperatures to determine if permafrost formed and the depth of the active layer in 1998-1999 at the Smith Lake 1 Site. 

3. Give the students the Yearly Averages for Smith Lake Site 1 Table and their Student Study Sheets.

4. Instruct them to complete Part IA.

5. Share results.  Clear up any misconceptions and reach a consensus about what the data indicates.

 

Part IB: Examining Yearly Data Charts

 

1.      Give students Charts 1, 2 and 3.

2.      Instruct them to complete Part IB.

3.      Share results. Clear up any misconceptions and reach a consensus about what the data indicates.

 

Part II: Examining Monthly Data  Data Tables 2 and 3 and Charts 4, 5, 6 and 7 

 

Estimated time required 1-40 minute class period. If students are preparing their own graphs by hand, they can start them in class and complete them and Part IIB of the Student Study Sheet as homework. Unless students are proficient in the use of Excel or another spreadsheet program, using the prepared charts is recommended.

 

NOTE:  Tables 2 and 3 contain median and standard deviation values. The values are not used in any of the examinations, but it might a good time to talk about what a median is and what a standard deviation indicates. A median is the middle of a distribution of values: half the values above and half the values below. The standard deviation is an indication of how tightly values are clustered around the average (mean) for the set of values.

 

Part IIA: Examining Monthly Data Tables 

 

1.      Review the results from Part I.

2.      Tell students the goal of Part II is to examine monthly data to look for more detailed information about the soil temperatures at the different depths in order to determine if permafrost existed during 1998-1999.

3.      Give students Tables 2 and 3.

4.      Instruct students to complete Part IIA of the Student Study Sheet.

5.      Share results. Clear up any misconceptions and reach a consensus about what the data indicates.

 

Part II B: Examining Monthly Data Charts 

 

1.      Give students Tables 2 and 3.

2.      Instruct students to complete Part IIB of the Student Study Sheet.

3.      Share results. Clear up any misconceptions and reach a consensus about what the data indicates.

 

Part III: Determining Maximum Active Layer Depth 

 

NOTE: Depending on the ability of your students, you might want to work together to complete potions of Part III.

 

1.      Tell the students that the goal of Part III is to determine the maximum active layer depth using the data presented in Tables 2 and 3. Review what an active layer is and discuss how the active layer differs from permafrost.

2.      Instruct students to complete Part III of the student study sheet down to question #3 or work together to complete the table.

3.      Share results. Clear up any misconceptions and reach a consensus about what the data indicates.

4.      Instruct students to complete the rest of Part III.

5.      Share the results. Clear up any misconceptions and reach consensus about what the data indicates.

6.      Review the results of the investigation and discuss what was difficult for them to understand.

7.      Discuss the information provided in the Resources below.

 

Resources:

 

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

   

Stories about Kenji Yoshikawa’s Yukon River project:

 

Permafrost Visualization Matures – permafrost monitoring goes high-tech