Polarimetric ALOS PALSAR time series in mapping biomass of boreal forests

dc.contributorAalto Universityen
dc.contributor.authorAntropov, Oleg
dc.contributor.authorRauste, Yrjö
dc.contributor.authorHäme, Tuomas
dc.contributor.authorPraks, Jaan
dc.contributor.departmentDepartment of Electronics and Nanoengineering
dc.contributor.departmentVTT Technical Research Centre of Finland
dc.description.abstractHere, we examined multitemporal behavior of fully polarimetric SAR (PolSAR) parameters at L-band in relation to the stem volume of boreal forests. The PolSAR parameters were evaluated in terms of their temporal consistency, inter-dependence and suitability for forest stem volume estimation across several seasonal conditions (frozen, thaw and unfrozen). The satellite SAR data were represented by a time series of PolSAR images acquired during several seasons in the years 2006 to 2009 by the ALOS PALSAR sensor. The study area was in central Finland, and represented a managed area in typical boreal mixed forest land. Utility of different PolSAR parameters, their temporal stability and cross-correlations were studied along with reference stand-level stem volume data from forest inventory. Further, two polarimetric parameters, cross-polarization backscatter and co-polarization coherence, were chosen for further investigation and stem volume retrieval. A relationship between forest stem volume and PolSAR parameters was established using the kNN regression approach. Ways of optimally combining PolSAR images were evaluated as well. For a single scene, best results were observed with polarimetric coherence (RMSE ≈ 38.8 m3/ha) for scene acquired in frozen conditions. An RMSE of 40.8 m3/ha (42.9%, R2 = 0.66) was achieved for cross-polarization backscatter in the best case. Cross-polarization backscatter was a better predictor than polarimetric coherence for few summer scenes. Multitemporal aggregation of selected PolSAR scenes improved estimates for both studied PolSAR parameters. Stronger improvement was observed for coherence with RMSE down to 34 m3/ha (35.8%, R2 = 0.77) compared to 38.8-51.6 m3/ha (40.8-54.3%) from separate scenes. Finally, the accuracy statistics reached RMSE of 32.2 m3/ha (34%, R2 = 0.79) when multitemporal HHVV coherence was combined with multitemporal HV-backscatter.en
dc.description.versionPeer revieweden
dc.identifier.citationAntropov , O , Rauste , Y , Häme , T & Praks , J 2017 , ' Polarimetric ALOS PALSAR time series in mapping biomass of boreal forests ' , Remote Sensing , vol. 9 , no. 10 , 999 . https://doi.org/10.3390/rs9100999en
dc.identifier.otherPURE UUID: 471119b4-a693-4ff0-b27b-5155a148b474
dc.identifier.otherPURE ITEMURL: https://research.aalto.fi/en/publications/471119b4-a693-4ff0-b27b-5155a148b474
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dc.relation.ispartofseriesRemote Sensingen
dc.relation.ispartofseriesVolume 9, issue 10en
dc.subject.keywordALOS PALSAR
dc.subject.keywordBoreal forest
dc.subject.keywordSAR polarimetry
dc.subject.keywordStem volume
dc.subject.keywordSynthetic aperture radar
dc.subject.keywordTime series
dc.titlePolarimetric ALOS PALSAR time series in mapping biomass of boreal forestsen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi