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2.4.4. Measurements Using Remote Sensing
Satellite remote sensing may be used to determine initial areas of different
land-cover types, including forests; to determine the extent, rates of change,
and locations of activities that result in forest cleaing and regrowth; to determine
the extent, rates of change, and locations of some of the additional activities
that may be agreed on; and to determine other natural and human-induced changes
in terrestrial ecosystems. The utility of data from satellites raises the question
of whether such data will be used as a primary source of data by countries reporting
sources and sinks of carbon or whether they will be used for verification.
2.4.4.1. Determining Initial Conditions
Satellite data (NOAA-AVHRR, synthetic aperture radar) have been used to create
global maps of land cover and forest cover (Belward et al., 1999; De
Grandi et al., 1999; Rosenqvist et al., 2000). Existing maps generally
have resolutions of 1 km, but future capabilities at 30-m resolution may be
possible with data from Landsat-7 in conjunction with other satellites. National-level
and global observation strategies have been proposed for monitoring changes
in forest cover (Skole et al., 1997).
Several active research efforts in laboratories in different countries continue
to explore the potential applications of these data sets and seek to update
them with new information as new optical measurements become available from
SPOT-Vegetation and MODIS (e.g., Running et al., 1994a,b; Townshend et
al., 1994; Belward et al., 1999). One approach consists of direct
parameterization of land-cover characteristics that are relevant to carbon studies,
such as vegetation structure and percentage of woody vegetation (DeFries et
al., 1995, 2000). Another option is the development of a multi-resolution
approach to global forest mapping. Such an approach would use coarse-resolution
satellite data to determine a sampling frame within which higher resolution
data would be nested. All of these methods are feasible within a scientific
research agenda, but they would require further development-including calibration
and evaluation with ground truth-for routine operational use.
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