ESTIMATES OF FOREST GROWING STOCK VOLUME OF THE NORTHERN HEMISPHERE FROM ENVISAT ASAR

摘要

This paper presents and assesses a dataset of forestrngrowing stock volume (GSV) above 30°N estimatedrnfrom multi-temporal backscatter measurements acquiredrnby Envisat Advanced Synthetic Aperture Radar (ASAR)rnin ScanSAR mode. The retrieval was based on thernBIOMASAR algorithm that combines standard SARrnprocessing techniques for multi-temporal SAR data andrnan automated GSV estimation approach based on arnWater Cloud-like model and a weighted combination ofrnGSV estimates from individual measurements of thernSAR backscatter. Approximately 70,000 ASAR imagesrnwere used to estimate GSV at a pixel size of 0.01°.rnAssessment of the retrieved GSV indicated (ⅰ) thernimportance of comparing to reference data at the samernscale, (ⅱ) moderate agreement with reference datasets atrnfull resolution because of the limited sensitivity of CbandrnSAR backscatter to GSV, (ⅲ) strong agreementrnwith reference datasets after aggregation at regional andrnnational level, (ⅳ) consistent retrieval resultsrnthroughout the study area, (ⅴ) saturation atrnapproximately 300 m~3/ha.