volume of the land products from the EOS 
Moderate Resolution Imaging Spectrometer 
(MODIS) sensor, for example, is estimated 
to total one hundred terabytes of data by 
the year 2000. This is in addition to 
hundreds of terabytes of raw data. In order 
to prepare the mechanisms and procedures 
to cope with the data volume and fulfillment 
of user requirements, EOS initiated a series 
of Pathfinder projects to assist in the 
development of EOSDIS capabilities using 
data from currently operational remote 
sensing systems. 
One of the primary Pathfinder activities 
undertaken by the EDC DAAC is production 
of the global land 1-km advanced very high 
resolution infrared radiometer (AVHRR) 
data set (Eidenshink and Faundeen 1994). 
The global land 1-km data set project 
represents an international effort to acquire, 
archive, process, and distribute 1-km 
AVHRR data of the entire global land 
surface in order to meet the needs of the 
international. science community. The 
partnership of the USGS, NASA, NOAA, the 
European Space Agency (ESA) the 
Commonwealth Scientific and Industrial 
Research Organization of Australia, and a 
network of nearly 30 high resolution picture 
transmission (HRPT) ground stations have 
been acquiring daily global land coverage 
since April 1, 1992. In addition, the 
International Geosphere Biosphere 
Program - Data and Information System 
(IGBP-DIS) and the Committee on Earth 
Observation Satellites (CEOS) have 
provided coordination of the international 
scientific community to facilitate 
development of processing standards 
(Townshend, 1992). | 
The scientific requirements for the data set 
are broad in scope and international in 
coverage. The IGBP-DIS land cover 
90 
working group completed a study that 
stressed the need for a this data set for 
mapping global land cover. The United 
Nations Food and Agriculture 
Organization's Forest Resources 
Assessment 1990 Project requires 1-km 
AVHRR data for all the forested lands on 
the planet, with emphasis on the tropical 
zones, for their global forest inventory 
mandate (FAO, 1990). NOAA researchers 
required a 1-km AVHRR data set of the 
northern hemisphere to study the urban 
heat island effects on surface observations 
of temperature data (Gallo et al., 1993). 
The Commission of the European 
Communities (CEC) and the ESA have a 
joint requirement for global, near daily, 
long-term, consistent optical and thermal 
satellite data for tropical environments in 
support of the joint Tropical Ecosystem 
Environment Observations by Satellite 
(1991) project The NASA Moderate 
Resolution Imaging Spectrometer (MODIS) 
land science team concluded that a global 
land 1-km AVHRR data set is crucial to 
develop algorithms for several land 
products for the Earth Observing System 
(EOS) (Running et al., 1993). Although 
there are many differences in AVHRR and 
MODIS sensor characteristics, the daily 
data volume of global AVHRR land 
coverage at 1.1 kilometer resolution and the 
pole-to-pole coverage provides a test bed 
for development of higher level derivative 
products and management and 
dissemination of large volumes of data. 
The Global Land 1-km AVHRR Data Set 
The data set is composed of 5-channel, 10- 
bit, raw AVHRR data, at 1.1-km resolution 
(at nadir) for every daily afternoon orbit 
over all land and coastal zones. Two 
products are available from the global 1-km 
project: raw data and 10-day vegetation 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996