AVHRR - Normalized Difference Vegetation Index (NDVI)
The "Normalized Difference Vegetation Index derived from NOAA-AVHRR data (NDVI_AVHRR)" is a fixed grid map (in stereographic projection ) with a spatial resolution
of 1.1 km at the center of the satellite map at 51.00 N / 15.00 E.
The operational production chain at DFD was launched on July 1st, 1994. Since then, daily, weekly and monthly NDVI synthesis maps covering the European continent are available until September 13rd, 1994, when the AVHRR on board the NOAA11 spacecraft failed. The production of daily, weekly and monthly NDVI maps was resumed on February 20th, 1995, based on NOAA14 AVHRR data. NOAA14 AVHRR sensor became some technical difficulties, so the generation was stopped on October 3rd, 2001. Since March 2002 NOAA16 AVHRR NDVI maps are available. With the beginning of January 2004, the data of AVHRR on board of NOAA16 exhibited some abnormal features showing strips in the scenes. Facing the "bar coded" images of NOAA16 AVHRR which occurred first in September 2003, continued in January 2004 for the second time and appeared in April 2004 again, DFD has decided to stop the reception of NOAA16 data on April 6th, 2004, and to start the reception of NOAA17 data on this day. On April 7th, 2004, the production of all former NOAA16 AVHRR products as e.g. the NDVI composites was successfully established. Please remember that NOAA17 is an AM sensor which passes central Europe about 2 hours earlier than NOAA16 (about 10:00 UTC instead of 12:00 UTC for NOAA16).
Ocean and lake areas are blue, clouds are masked out as bad values (white).
Special emphasis is given to a precise image registration and a reasonable cloud screening procedure to ensure that only cloud free pixels are taken for the later process of composition. Due to the importance of these two tasks, the generation of the NDVI products is a mixture of unsupervised pre-processing steps and a supervised parameterization of the cloud tests and an image navigation control. Thus, before an image was sent to the data archive and becomes available to the user, it was manually controlled regarding the navigation quality and the cloud tests.
Daily maps are composed based on the Maximum Value (MV) criterion at every pixels' position which normally consist of three consecutive NOAA11 (NOAA14, NOAA16 or NOAA17) passages (east, central, west). From these daily products, weekly and monthly synthesis maps are derived taking the daily MV.
The NDVI range starts with "-0.09968454" and is referred to Grey value "1". The radiometric resolution is "0.0031546", Grey value 254 is therefore referred to value "0.7" (maximum NDVI).
More detailed information can be seen here.
Dech, S., Tungalagsaikhan, P., Preusser, C., & Meisner, R., 1998. Operational value-adding to AVHRR data over Europe: methods, results, and prospects. Aerospace Science and Technology, 5, 335-346.
Tungalagsaikhan P., Günther K.P., Gesell G., Dech S.W., Ruppert T. Operational processing of AVHRR data at DFD. In: Tagungsbände der Wissenschaftlich-Technischen Jahrestagungen der DGPF, Band 12: Auf dem Weg zu operationellen Prozessketten in Photogrammetrie, Fernerkundung und Geoinformation, 23. Jahrestagung der DGPF, Bochum 2003, pp. 464, 2003.
The NDVI is an important factor describing the biological status of canopies. This product is thus used by scientists for deriving plant and canopy parameters. Consultants use time series of the NDVI for advising farmers with best practice.
Contact: Dr. Kurt P. Günther