Background

The Aspen Fire started on June 17, 2003 and ended June 30, 2003. The fire burned 84,750 acres on Mount Lemmon, northeast of Tucson, Arizona. The fire destroyed 333 structures.

In this exercise, you will view the effects of the Aspen Fire on vegetation greenness in 2003.

Objectives

Use the Dynamic Animation tool to…

• Understand difference from last period’s greenness data
• Learn about pixels

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 Aspen 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 “Greenness (NDVI)” for the data type in the left viewer and “Difference from Last Period’s NDVI” for the data type in the right viewer. Select 2003 as the year for both viewers. Click Refresh.

   Knowing that orange areas have increased in greenness since the previous period and blue areas have decreased in greenness, what color do you expect the fire area to appear after the fire occurs?

3. Select the checkboxes next to "Highways" to turn on the layer and labels. Click Refresh.

4. Select the “Zoom In” tool at the top of the screen. Click twice to zoom in where the I-10 and the I-19 intersect. Northeast of the intersection, Mt. Lemmon appears as a triangular-shaped, highly vegetated area.

5. Click twice on Mt. Lemmon to zoom in more. Add any appropriate layers to the image viewers. Click the Animate button.

Discussion Questions

If the fire started on June 17, 2003, why do you not see evidence of the fire in the June 24, 2003 image? (Hint: Consider the length of the compositing period. See Range Monitoring Application for details.)

When did you first see evidence of the fire?

Which animation best showed the smoke from the fire? Which animation best showed the extent of the fire? Why?

In the July 8th image, what is the length and width of the fire? Remember: A pixel in an AVHRR greenness image is one kilometer on a side.
Length:   Width:

Where are the most recent effects of the fire in the July 8th image?
In the July 22nd image?

Additional Resources