Case Study 2.2 - Climate Variability in the North Atlantic

During this activity students will:

• Practice reading lat-lon contour plots of pressure and precipitation.
• Depict changes in pressure and precipitation over time on a map of the North Atlantic.
• Explain how pressure changes and precipitation patterns may be connected.
• Be able to explain the importance of examining an anomaly.

My goals in creating this activity were to:

• Provide students with practice interpreting data that vary in space and time.
• Illustrate relationships between precipitation and sea-level pressure in the North Atlantic.

This activity may be used as a follow-on or supplemental in-class exercise, laboratory assignment, or homework assignment for InTeGrate Climate of Change Module - Unit 2. Ideally, students understand how to read contour maps. For an extended lab or homework assignment, this activity may be combined with Case Study 3.2: Exploring Patterns - ENSO and NAO on the Global Stage. Case Study 3.2 asks students to focus on sea surface temperature anomalies and compare the NAO with the El Niño-Southern Oscillation, whereas this exercise asks students to identify pressure and precipitation anomalies. This activity will take approximately 30 minutes to 1 hour to complete, including a ~20-minute introduction.

The data for students are in a PowerPoint file. Depending on the format of the class, students may access these data electronically, or you may wish to make color or black-and-white printouts for students to view in class. There are three types of data: precipitation, precipitation anomalies, and pressure anomalies. The student handout posted here has questions that guide students through the examination of data.

Case Study 2.2 Student Handout (Microsoft Word 2007 (.docx) 44kB Sep2 24)

Case Study 2.2 Data Sheets (PowerPoint 2007 (.pptx) 726kB May12 14)

Case Study 2.2 Data Sheets (black-and-white version) (PowerPoint 2007 (.pptx) 625kB May12 14)

This activity may be easily modified, depending on whether students are in class, working in groups, or working individually, in class or at home. If students are working on the assignment individually, in a lab, or at home, they may access the data electronically, in PowerPoint. If completing this activity in class, students could be divided into groups, with one group examining the pressure data, and the other examining the precipitation data. The data could be available electronically or printed out.

Teaching Tips

In introducing this activity, it may be important to start by mentioning climate variability, as discussed in in Unit 1.

Introduce the North Atlantic Oscillation by first showing a January climatological surface pressure chart that illustrates the Icelandic Low and the Azores High. The NAO occurs when there are shifts in the Icelandic Low and the Azores High (students may not know where the Azores are, so it is important to point this out).

Introduce them to or review the term anomaly, and show students the different plots they will be looking at (precipitation and pressure). Students may need some explanation as to what the colors mean on the plots. Also, to draw connections with Unit 1, it might be helpful to mention the possible connection between the NAO and the Vikings.

Take a moment to get students to visualize what a 1 mm/day precipitation anomaly would mean for annual total precipitation.

Allow students to use globes to familiarize themselves with names of countries in the North Atlantic.

Keep students focused on the North Atlantic, and tell them not to pay attention to anomalies they see in Siberia.

In reviewing work on student handouts, you may also assess the following:

• Can students identify anomalies? (They must locate anomalies and describe the magnitude of these anomalies.)
• Are students able to make a connection between an anomaly and a climate impact? (This means they must be able to describe impacts associated with an anomaly (e.g. more rain in Spain during the negative phase of the NAO).
• Are students able to articulate an hypothesis regarding why pressure anomalies are having an impact on precipitation? (Students with very little background may suggest that changes in North Atlantic pressure are affecting rain or cloud formation. Students with more background may recognize that a shift in the pressure pattern can affect the jet stream, and that the piece of information they would need to confirm this hypothesis is upper level wind fields. The important thing here is that students take the time to develop an hypothesis, whether or not it is correct.)

Also, Case Study 3.2: Exploring Patterns - ENSO and NAO on the Global Stage may be used to assess how well students understand the changes that occur during each phase of the NAO.

Answers to the questions in the student handout are in this document:

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Data contained in the PowerPoint for this activity comes from the NCEP NOMADS Server containing NCEP Reanalysis model output. This activity could be modified or expanded with additional data from these sites. Alternatively, more advanced students could be directed to access these data themselves.