In this study, data characteristics for composited, multitemporal Advanced Very High
Resolution Radiometer data sets for Alaska were assessed for a 7- year period from 1991 to
1997. This involved consideration of the satellite sensors used, data processing performed, and
data set compilation, along with an analysis of acquisition date, solar zenith angle, satellite
viewing angle, presence of clouds, and registration accuracy for each year.
Each year?s worth of data are available on CD-ROM in byte format. All data sets have an
initial start date of April 1, but had varying ending dates (mid-September to late October)
because of satellite sensor malfunction or the presence of clouds or snow; no data set extended
beyond October 31. Satellite scan angles were summarized in seven categories: data obtained at
nadir, data within 30, 40, and 55 degrees of nadir, data greater than 55 degrees off nadir, and
proportions of the data representing east or west look angles. Minimum, maximum, and average
solar zenith angles were provided for each period. Estimates of cloud cover for each period were
based on three tests: reflectance gross cloud test, channel 3 minus channel 4, and channel 4
minus channel 5. Registration accuracy was estimated using a gray-level autocorrelation
Results of this investigation indicate that the composited data available on CD-ROM
should be useful for a number of different regional assessments of Earth cover properties.
However, caution is advised when using these data because (1) loss in precision from the
conversion to a byte format, (2) low sun angles and high viewing angles in the September and
October data, and (3) registration inaccuracies of 2 to 8 pixels.
Additional publication details
USGS Numbered Series
Characteristics of the Alaskan 1-Km Advanced Very High Resolution Radiometer data sets used for analysis of vegetation biophysical properties
U.S. Dept. of the Interior, U.S. Geological Survey,