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Bandwidth Effects in POL-INSAR Forest Parameter Estimation Performance at P-Band

Seung-Kuk Lee(1), Florian Kugler(1), Kostas Papathanassiou(1), Rolf Scheiber(1) and Irena Hajnsek(1)

(1) German Aerospace Center (DLR), P.O. Box 1116, 82234 Wessling, Germany


Polarimetric SAR interferometry (Pol-InSAR) is a radar-imaging technology with important application in the remote measurement of vegetation parameters such as forest height, (vertical) structure and biomass. Indeed, model based (using the Random Volume over Ground (RVoG) model) forest height estimation has been successfully demonstrated using airborne repeat pass fully polarimetric interferometry at different frequencies (P-/L-band and X-band) for a wide range of forest and terrain conditions. considering the different spaceborne missions scenarios proposed at lower frequencies (L- and P-band) for global vegetation biomass mapping The important relation of forest height and structure to forest biomass makes the estimation of forest height and vertical structure by means of Pol-InSAR an actual and important topic.

In this paper we evaluate and compare the performance of forest height, vertical structure, and biomass estimation techniques with respect to the restrictions arising from a space-borne implementation at L- and P-band. The differences between these two frequencies become pronounced when projected into a repeat-pass space-borne implementation: On the one hand side, P-band is characterized by higher temporal stability than L-band, a fact that reduces the impact of temporal decorrelation on the parameter inversion. However, this key advantage is counteracted by the limited frequency allocation available for P-band: the International Telecommunication Union (ITU) allocates a 6 MHz bandwidth at 432-438 MHz while at L-band 85 MHz between 1.215-1.300 GHz are available. The limited system bandwidth do not only reduces the spatial resolution but also restricts the ability to realize large spatial baselines needed to compensate un-calibrated decorrelation contributions (induced by system and temporal effects). Bandwidth and additional system parameters (as NESZ, SAAR, spatial sampling and resolution) are accounted (and simulated) in order to provide a realistic baseline for the comparison. The performance analysis is supported by simulated space-borne data obtained from the extrapolation of real airborne Pol-InSAR data acquired in the frame of the BioSAR (2008) and the INDREX-II (2005) campaigns. Finally, we discuss the impact of observation scenario (e.g. revisit time and spatial baselines) and provide a (very) first assessment on the impact of ionosphere - that is also different for the two frequencies - on the product generation performance.


Workshop presentation


  Higher level                 Last modified: 07.05.06