Document


Title

Radar estimates of aboveground biomass in boreal forests of interior Alaska
Document Type: Journal Article
Author(s): Eric J. Rignot; JoBea Way; Cynthia L. Williams; Leslie A. Viereck
Publication Year: 1994

Cataloging Information

Keyword(s):
  • aboveground biomass
  • Bonanza Creek LTER
  • boreal forest
  • fuel loading
  • radar
  • SAR data
Topic(s):
Region(s):
Record Maintained By:
Record Last Modified: December 3, 2015
FRAMES Record Number: 5006

Description

Airborne SAR data gathered by the NASA/JPL three-frequency, polarimetric, radar system in winter, spring, and summer over the Bonanza Creek Experimental Forest, near Fairbanks, AK, are compared to estimates of whole-tree aboveground dry biomass from 21 forest stands and two clear-cuts. While C-band radar backscatter shows little sensitivity to biomass, L- and P-band radar backscatter increase by more than 6 dB when biomass increases from 5 to 200 tons/ha. Using second-order polynomial regressions, biomass values are predicted from the radar at L- and P-band and compared to actual biomass values. At P-band HV-polarization, the error in predicted biomass is about 30% of the actual biomass. When HV-, HH-, and VV-polarization are used together in the regression, the error in predicted biomass is about 20%. Errors obtained using L-band data are a few percents larger. These errors are caused by uncertainties in actual stand biomass estimates, significant inner-stand spatial variations in biomass, unusual conditions of forest stands following natural disturbances, along with interactions of the radar signals with a complex three-dimensional structure of the canopy. Multiple incidence angle data reveal that the incidence angle theta sub(i) of the radar illumination is also a factor influencing the retrieval of biomass, even at HV-polarization, when theta sub(i) > 50 degree or theta sub(i) < 25 degree . Finally, the radar response of the forest - and thereby the regression curves for biomass retrieval - are dependent on the seasonal and environmental conditions.

Online Link(s):
Citation:
Rignot, Eric J.; Way, JoBea; Williams, Cynthia L.; Viereck, Leslie A. 1994. Radar estimates of aboveground biomass in boreal forests of interior Alaska. IEEE Transactions on Geoscience and Remote Sensing 32(5): 1117-1124.