Rocky Mountain Research Station Publications
RMRS Online Publication
RMRS-GTR-26CD: Vegetation greenness and fire danger images: Image archives; Greenness 1989-1998; Fire Danger 1996-1998
Burgan, Robert E.; Chase, Carolyn H.; Bradshaw, Larry S. 1998. Vegetation greenness and fire danger images: Image archives; Greenness 1989-1998; Fire Danger 1996-1998. Gen. Tech. Rep. RMRS-GTR-26-CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 1 CD-ROM.
This CD-ROM contains GIF images of four vegetation greenness themes derived from Normalized Difference Vegetation Index (NDVI) data for the years 1989 through 1998 and three fire danger themes for 1996 and 1998. The GIF images are referenced by an HTML document and thus can be viewed using any standard browser such as Internet Explorer or Netscape.
Please note some cautions regarding images derived from NDVI data. NDVI provides a means to observe vegetation greenness from satellite data. The satellites make observations daily for the entire united States, but factors such as cloudiness, smoke or haze, and poor viewing angle can reduce the quality of the observed data. To compensate for this, several days' NDVI observations are composited for each pixel, with only the highest NDVI value observed during the composite period being saved. From 1989 through 1995, 14 days of daily NDVI images were used to make 2 week composites. This greatly reduces problems caused by cloudiness, but it dues not entirely eliminate them. Additionally, such a long composite period creates a delay in observing vegetation curing.
In 1996 the composite period was reduced to 7 days. This improves the usefulness of the images during periods of rapid vegetation curing, but it comes at the expense of additional cloud contamination. Regardless of what the composite period is, care must be taken in interpreting the images.
If an NDVI map, or one of the maps derived from NDVI (Visual Greenness, VG; Relative Greenness, RG; Departure From Average Greenness, DA; and Live Shrub Moisture, MO), appears to be affected by cloudiness, look at the image for one period before and one period after the current image. If an area exhibits suspiciously low vegetation greenness and shows higher greenness in the image before or after the current image, the current image is likely showing cloud or smoke contamination.
You will see white areas in some images. These indicate clouds, snow, or other nongreen surfaces. Often a "fringe," sometimes rather large, may be evident around cloudy pixels. Snowy areas viewed under clear conditions generally have a narrow band or surrounding low vegetation greenness.
You will also see three fire danger maps: fire danger, Keetch-Byram Drought Index; and 1,000-hour timelag fuel moisture. These maps depict five fire danger adjective classes interpolated from reporting weather stations. The interpolation makes no adjustment for the effects of terrain.
For additional information on the Forest Service's vegetation and fire danger assessment program using satellite data, or comments about the CD-ROM, contact:
Fire Sciences Laboratory
PO Box 8089
Missoula, MT 59807 USA
Phone: (406) 329-4820
FAX: (406) 32924825
This publication is not available online. The contents were published on a CD and are only available in that format. Please click here to order the CD of this publication.
A duplicate CD-ROM may also be purchased from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: (800) 553-6847
Vegetation greenness and fire danger images: Image archives; Greenness
1989-1998; Fire Danger 1996-1998
Electronic Publish Date: August 22, 2008
Last Update: August 22, 2008
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