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Vegetation Condition from AVHRR NDVI Data
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Vegetation Condition images based on NDVI (Normalized Difference Vegetation Index) are available for viewing at this site. The NDVI measures vegetation vigor caused by chlorophyll activity; this is sometimes called "greenness". These data have proven valuable to USDA policy officials in providing geographic location and monitoring information for vegetation condition in crop areas. Effects of the massive Midwest flood in 1993, the mid-Atlantic drought of 1999, and the 2002 winter wheat drought in the southwest.

The Vegetation Condition data selectable below are arranged by two week composite periods covering the 1995 - 1999, 2001-2003, and 2004 (as available) crop seasons. The NOAA-14 satellite collected images from the 1995 through the 1999 crop season. The NOAA-16 satellite collected images from the 2001 through 2003 seasons. NOAA-16 started malfuntioning in early 2004, when a scan motor problem caused a 'barcode' appearence. The NOAA-17 satellite is being used to replace NOAA-16 for 2004, but the data are not directly comparable, so no ratios of current data to previous periods will be attempted. Images since the start of the 2001 season are not water vapor corrected. Animations of these images for a given year reveal how the vegetation condition changes during the growing season.

Select a 2004 Biweekly Period to View:
03/11-03/24 03/25-04/07 04/08-04/21 04/22-05/05
05/06-05/19 05/20-06/02 06/03-06/16 06/17-06/31
07/01-07/14 07/15-07/28 07/29-08/11 08/12-08/25
08/26-09/08 09/09-09/22 09/23-10/06 10/07-10/20

Available Years
NOAA-17: 2004
NOAA-16: 2003 2002 2001
NOAA-14: 1999 1998 1997 1996 1995

For more information about this topic or about the NASS Spatial Analysis Research Section (SARS), Contact Rick Mueller at Rick_Mueller@nass.usda.gov, telephone number (703)877-8000 x111.
Growing Season Animations | Weekly Weather & Crop Bulletin
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