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system provides. Landsat provides wide area coverage, but is limited 
in spatial resolution and the placement and number of spectral bands. 
Helicopter-spectrometer and aircraft scanner data were collected 
over commercial fields in a series of flightlines over the LACIE in- 
tensive test site in each county.  Landsat data were acquired over 
the entire test site as well as surrounding areas. These data provide 
a measure of the natural variation in the temporal-spectral character- 
istics of wheat and surrounding cover types. The staging of data 
acquisition is summarized in Figure 2. 
The truck-mounted spectrometers collected spectra of controlled 
experiemntal plots growing at agricultural research stations near the 
test sites at Garden City, Kansas, and Williston, North Dakota. These 
data, combined with the more detailed and quantitative measurements of 
crop and soil conditions which were made on the experiment stations, 
enable more complete understanding and interpretation of the spectra 
collected from commercial fields. Past experience has shown that there 
are generally too many interacting variables in commercial fields to 
determine exactly what is the cause of observed differences in spectral 
response. With data from plots where only two to four factors are 
varied under controlled conditions, it is possible to better determine 
and understand the energy-matter interactions occuring in crops. 
The spectral measurements were supported by descriptions of the 
targets and their condition. These data include descriptive observa- 
tions, counts, and measurements of the crop canopy including: maturity, 
plant height, biomass, leaf area index, percent soil cover, and grain 
yield. Also included are the measurement conditions such as sensor 
altitude and view angle, as well as measurements of the atmospheric 
and meteorological conditions. The data are supplemented by aerial 
photography and ground-level vertical and oblique photographs of the 
fields and test plots. 
A data library of all spectral, agronomic, and meteorological 
data collected is maintained at Purdue/LARS where the data are proc- 
essed in standard data formats and measurement units and are provided 
to NASA/JSC supported investigators and other interested researchers. 
Test Site and Experiment Descriptions 
The test sites were located in Finney County, Kansas; Williams 
County, North Dakota; and Hand County, South Dakota. Each site 
consists of a LACIE intensive test site; and in Kansas and North 
Dakota, an agricultural research station. Three years of measurements 
were acquired at the Kansas and North Dakota sites and two years at 
the South Dakota site. 
The test sites were chosen to include as wide a range of impor- 
tant wheat production areas as possible. In addition, the Finney and 
Williams County sites were selected because of their close proximity