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Articles | Volume XLIII-B3-2021
Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLIII-B3-2021, 127–134, 2021
https://doi.org/10.5194/isprs-archives-XLIII-B3-2021-127-2021
Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLIII-B3-2021, 127–134, 2021
https://doi.org/10.5194/isprs-archives-XLIII-B3-2021-127-2021

  28 Jun 2021

28 Jun 2021

INVESTIGATION OF SENTINEL-1 TIME SERIES FOR SENSITIVITY TO FERN VEGETATION IN AN EUROPEAN TEMPERATE FOREST

M. M. Mueller1,2, C. Dubois1, T. Jagdhuber3,4, C. Pathe1,2, and C. Schmullius1 M. M. Mueller et al.
  • 1Department for Earth Observation, Institute of Geography, Friedrich Schiller University, Jena, Germany
  • 2Institute of Data Science, German Aerospace Center, Jena, Germany
  • 3Microwaves and Radar Institute, German Aerospace Center, Wessling, Germany
  • 4Institute of Geography, University of Augsburg, Augsburg, Germany

Keywords: Sentinel-1, time series, backscatter, phenology, undergrowth, seasonality, fern

Abstract. In this study, a dense Copernicus Sentinel-1 time series is analyzed to gain a better understanding of the influence of undergrowth vegetation, in particular of eagle fern (Pteridium aquilinum), on the C-band SAR signal in a temperate forest in the Free State of Thuringia, Germany. Even if signals from the ground below the canopy may not be expected at C-band, previous studies showed seasonal fluctuations of the backscatter for temperate forests without canopy closure, notably for evergreen coniferous stands. Many factors can be responsible for these observed fluctuations, but in this study, we analyze one possible factor: the presence of undergrowth vegetation, in particular, of fern. Especially, the Sentinel-1 backscatter signal is analyzed for different acquisition configurations regarding its temporal and its spatial stability at different growth stages. This time series study shows that a difference of backscattered signal of up to 0.7 dB exists between forest patches with a dense fern density in the understory and the ones with low undergrowth vegetation. This signal difference depends on the season and is remarkably strong comparing winter (no fern undergrowth) with summer (major fern undergrowth).