Analyzing the Antarctic Ozone Hole (College Level)
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.
This example describes general tips to adapt a chapter from the Earth Exploration Toolbook for use at the college level. In the EET chapter, users examine satellite images that show how much ozone is in the atmosphere over the Southern Hemisphere. They interpret the images to identify the ozone "hole" that develops over this region each summer, and compare its size from year to year.
Using freely available image analysis software, ImageJ, users quantify the area of the Antarctic ozone hole each October from 1996 to 2004. Finally, they bring their measurements into a spreadsheet program and create a graph to document changes in the size of the ozone hole. The original EET chapter is written for high school levels as a supervised classroom exercise. Much of the work could be done by college-level students as a lab or take-home exercise.
After completing this chapter, users will be able to:
- Interpret satellite images to understand global distribution of ozone
- Identify the Antarctic ozone hole in satellite images
- Analyze images to quantify the area of the ozone hole over time
- Produce a graph showing area of the ozone hole over time
Context for Use
Description and Teaching Materials
The original Earth Exploration Toobook chapter, Analyzing the Antarctic Ozone Hole provides a comprehensive description of the data set, tools, and teaching methods, as well as step-by-step instructions for the exercise.
The "Going Further" page of the EET chapter provides links to additional data sources and ideas for other activities that utilize the data sets.
Teaching Notes and Tips
The original EET chapter was written for high school level as a classroom exercise with significant instructor suppervision. The tools and techniques used in the exercise are important aspects of geoscience research. College-level students should be able to follow the step-by-step instructions of the EET exercise in a lab or take-home exercise setting.
This exercise uses remote sensing data to analyze the extent of the southern hemisphere ozone hole over time. Students can use the free image analysis software, ImageJ, to measure the extent of the hole in multiple images covering a number of weeks, months, or years. To provide more freedom to explore the data, the students may be asked to determine an appropriate time-span and number of images necessary to analyze seasonal or multi-year changes in the extent and intensity of the ozone hole.
Some students may find the software download and installation intimidating and may have problems on public computers that limit the ability to install new software (talk to your I.T. department). However, the comprehensive instructions in the EET chapter should help them along.
Tracing the ozone hole edges may seem arbitrary to some students and they may find that the relative lack of precision (repeatability) frustrating, especially when they find different answers than their classmates. This is a good opportunity to discuss the concepts of precision and interpretation error. They could also explore ideas on how to construct an automated routine (algorithm) to minimze such errors.
Students unfamiliar with Excel may want to review a primer on the program.
Report of the analysis including imagery, traced areas of interest, a table of observations/measurements/calculations. Assessment can be based on the accuracy of the results and how well the students have mastered the image analysis methods.
References and Resources
Detailed download/installation instructions from the EET chapter.
What is Excel? - a tutorial on how to use Excel to analyze and plot data