| Summary: | Changes in the seasonal CO 2 flux of the boreal forests may result from increased atmospheric CO 2 concentrations and associated atmospheric warming. To monitor this potential change, a combination of remote sensing information and ecophysiological models are required. In this paper we address the use of synthetic aperture radar (SAR) data to provide some of the input to the ecophysiological models: forest type, freeze/thaw state which limits the growing season for conifers, and leaf on/off state which limits the growing season for deciduous species. AIRSAR data collected in March 1988 during an early thaw event and May 1991 during spring breakup are used to generate species maps and to determine the sensitivity of SAR to canopy freeze/thaw transitions. These data are also used to validate a microwave scattering model which is then used to determine the sensitivity of SAR to leaf on/off and soil freeze/thaw transitions. Finally, a CO 2 flux algorithm which utilizes SAR data and an ecophysiological model to estimate CO 2 flux is presented. CO 2 flux maps are generated from which areal estimates of CO 2 flux are derived.
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