Background

The Rodeo-Chediski Fire started on June 18, 2002 and ended July 7, 2002. The fire burned in the Tonto & Apache-Sitgraeves National Forest and other portions of east central Arizona. The largest fire in Arizona history, it burned 467,066 acres.

In this exercise, you will view the effects of the Rodeo-Chediski Fire on vegetation greenness in 2002 and observe its recovery in 2003.

Objectives

Use the Dynamic Animation tool to…

• Understand difference from last year’s greenness data
• View the effects of the recent Aspen Fire and look at the difference in greenness between the fire and non-fire periods

Tools

This exercise uses the AVHRR Dynamic Animation Tool (link opens in separate window).

To find the tool without the direct link:
     1) In your Internet browser, go to http://rangeview.arizona.edu.
     2) Click on “Dynamic Animation with AVHRR Data” in the Tools box on the home page.

Exercise

Identifying the Rodeo-Chediski Fire

1. Choose Arizona from the “Zoom to” menu at the top of the screen. Wait a few seconds for the image viewers to refresh.

2. Select both checkboxes next to "FS Land" to make the layer and labels visible. Click the Refresh button.

3. Select the “Zoom in” button at the top of the screen and click on the Apache-Sitgraeves National Forest. Click again to zoom in farther.

4. In the left image viewer: Choose “Greenness” as the data type and 2002 from the year menu.
   In the right image viewer: Choose “Difference from Last Year” as the data type, and select 2003 as the year.
   Click Refresh.
   
   What color will areas that are less green in 2003 than in 2002 appear?
   What color will areas that are more green in 2003 than in 2002 appear?
   
   

5. Locate the large, solid blue area in the “Difference from Last Year” image in the right viewer. Click once more in the center of this area to zoom in on the fire.

6. Click the Animate button to render a series of images and play the animation.

Discussion Questions

Greenness Images

Play the animation once through, looking only at the 2002 greenness images in the left image viewer.

In which image did you first see evidence of the fire?

Use the “Step Forward,” or “Step Backward” buttons to alternate between the image with the fire and the previous image to see the dramatic change in vegetation greenness. Which dataset would highlight this change well?

How does the smoke trailing to the northeast affect the greenness values?

Can you continue to see the effects of the fire after July?

At the very end of August, the area surrounding the fire becomes green again. What caused this?

Difference Images

Play the animation again, paying special attention to the “Difference from Last Year” images in the right viewer.

In which “Difference from Last Year” image do you first see the fire scar clearly?

What do you think happened in March that made 2003 appear so much less green than in 2002?

Assuming that vegetation greenness is most greatly affected by climate and precipitation, which year is more dry from April to June, 2002 or 2003? (Hint: Look at the area surrounding the fire scar.)

Why does it suddenly appear more green in 2003 than in 2002 from July on?

Does this suggest that the area is improving?

Additional Resources