{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T12:28:21Z","timestamp":1770985701785,"version":"3.50.1"},"reference-count":55,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2019,7,17]],"date-time":"2019-07-17T00:00:00Z","timestamp":1563321600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000844","name":"European Space Agency","doi-asserted-by":"publisher","award":["4000115192\/15\/NL\/AF\/eg"],"award-info":[{"award-number":["4000115192\/15\/NL\/AF\/eg"]}],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The planned launch of a spaceborne P-band radar mission and the availability of C- and L-band data from several spaceborne missions suggest investigating the complementarity of C-, L-, and P-band backscatter with respect to the retrieval of forest above-ground biomass. Existing studies on the retrieval of biomass with multi-frequency backscatter relied on single observations of the backscatter and were thus not able to demonstrate the potential of multi-temporal C- and L-band data that are now available from spaceborne missions. Based on spaceborne C- and L-band and airborne P-band images acquired over a forest site in southern Sweden, we investigated whether C- and L-band backscatter may complement retrievals of above-ground biomass from P-band. To this end, a retrieval framework was adopted that utilizes a semi-empirical model for C- and L-bands and an empirical parametric model for P-band. Estimates of above-ground biomass were validated with the aid of 20 m-diameter plots and a LiDAR-derived biomass map with 100 m \u00d7 100 m pixel size. The highest retrieval accuracy when not combining frequencies was obtained for P-band with a relative root mean square error (RMSE) of 30% at the hectare scale. The retrieval with multi-temporal L- and C-bands produced errors of the order of 40% and 50%, respectively. The P-band retrieval could be improved for 4% when using P-, L-, and C-bands jointly. The combination of C- and L-bands allowed for retrieval accuracies close to those achieved with P-band. A crucial requirement for achieving an error of 30% with C- and L-bands was the use of multi-temporal observations, which was highlighted by the fact that the retrieval with the best individual L-band image was associated with an error of 61%. The results of this study reconfirmed that P-band is the most suited frequency for the retrieval of above-ground biomass of boreal forests based on backscatter, but also highlight the potential of multi-temporal C- and L-band imagery for mapping above-ground biomass, for instance in areas where the planned ESA BIOMASS P-band mission will not be allowed to acquire data.<\/jats:p>","DOI":"10.3390\/rs11141695","type":"journal-article","created":{"date-parts":[[2019,7,17]],"date-time":"2019-07-17T11:25:12Z","timestamp":1563362712000},"page":"1695","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Benchmarking the Retrieval of Biomass in Boreal Forests Using P-Band SAR Backscatter with Multi-Temporal C- and L-Band Observations"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6890-1548","authenticated-orcid":false,"given":"Oliver","family":"Cartus","sequence":"first","affiliation":[{"name":"Gamma Remote Sensing, Worbstrasse 225, 3073 G\u00fcmligen, Switzerland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3339-6991","authenticated-orcid":false,"given":"Maurizio","family":"Santoro","sequence":"additional","affiliation":[{"name":"Gamma Remote Sensing, Worbstrasse 225, 3073 G\u00fcmligen, Switzerland"}]},{"given":"Urs","family":"Wegm\u00fcller","sequence":"additional","affiliation":[{"name":"Gamma Remote Sensing, Worbstrasse 225, 3073 G\u00fcmligen, Switzerland"}]},{"given":"Bj\u00f6rn","family":"Rommen","sequence":"additional","affiliation":[{"name":"European Space Agency-ESTEC, 2201 Noordwijk, The Netherlands"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Santoro, M., and Cartus, O. 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