Temporal survey of P- A nd L-band polarimetric backscatter in boreal forests
Journal article, 2018

Environmental conditions and seasonal variations affect the backscattered radar signal from a forest. This potentially causes errors in a biomass retrieval scheme using data from the synthetic aperture radar (SAR) data. A better understanding of these effects and the electromagnetic scattering mechanisms in forests is required to improve biomass estimation algorithms for current and upcoming P- A nd L-band SAR missions. In this paper, temporal changes in HH-, VV-, and HV-polarized P- A nd L-band radar backscatter and temporal coherence from a boreal forest site are analyzed in relation to environmental parameters. The radar data were collected from a stand of mature Norway spruce ( Picea abies (L.) Karst.) with an above-ground biomass of approximately 250 tons/ha at intervals of 5 min from January to August 2017 using the BorealScat tower-based scatterometer. It was observed that subzero temperatures during the winters cause large variations (4 to 10 dB) in P- A nd L-band backscatter, for which the HH/VV backscatter ratio offered some mitigation. High wind speeds were also seen to cause deviations in the average backscatter at P-band due to decreased double-bounce scattering. Severe temporal decorrelation was observed at L-band over timescales of days or more, whereas the P-band temporal coherence remained high (> 0.9) for at least a month neglecting windy periods. Temporal coherence at P-band was highest during night times when wind speeds are low.

synthetic aperture radar (SAR)

boreal forest


time series



temporal coherence


Albert Monteith

Chalmers, Space, Earth and Environment, Microwave and Optical Remote Sensing

Lars Ulander

Swedish Defence Research Agency (FOI)

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

1939-1404 (ISSN)

Vol. 11 10 3564-3577 8335779

Tower-based radar and geophysical measurements during the BorealScat experiment

European Space Research and Technology Centre (ESA ESTEC), 2016-11-01 -- 2018-04-30.

European Space Agency (ESA), 2016-11-01 -- 2018-04-30.

Subject Categories

Forest Science

Physical Geography

Climate Research



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